ada/gnatstudio
0
0
Fork 0
mirror of https://github.com/AdaCore/gnatstudio.git synced 2026-02-12 12:42:33 -08:00
Code Issues Packages Projects Releases Wiki Activity
Files
topic/codeowners
gnatstudio/share/predefined_ada.xml
Anthony Leonardo Gracio 801924c920 T626-020: update predefined_ada.xml 
Change-Id: I33a52f7015abf37b82ea8a175ed9f173ee3260fe
2020-08-15 14:58:58 +02:00

9724 lines
384 KiB
XML
Raw Permalink Blame History

<PREDEFINED_ADA>
<ASPECT id="0" name="Abstract_State" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Abstract_State: 1c.</DOC>
</ASPECT>
<ASPECT id="2/3" name="Address" origin="Ada RM" category="unknown">
<DOC>Machine address of an entity. See 13.3.</DOC>
</ASPECT>
<ASPECT id="3/3" name="Alignment" origin="Ada RM" category="unknown">
<DOC>Alignment of an object. See 13.3.</DOC>
</ASPECT>
<ASPECT id="4/3" name="Alignment" origin="Ada RM" category="unknown">
<DOC>Alignment of a subtype. See 13.3.</DOC>
</ASPECT>
<ASPECT id="5/4" name="All_Calls_Remote" origin="Ada RM" category="unknown">
<DOC>All indirect or dispatching remote subprogram calls and all
direct remote subprogram calls should use the Partition
Communication Subsystem. See E.2.3.</DOC>
</ASPECT>
<ASPECT id="0" name="Annotate" origin="GNAT RM" category="unknown">
<DOC>There are three forms of this aspect (where ID is an identifier, and
ARG is a general expression), corresponding to *note pragma Annotate:
26.
`Annotate =&gt; ID'
Equivalent to `pragma Annotate (ID, Entity =&gt; Name);'
`Annotate =&gt; (ID)'
Equivalent to `pragma Annotate (ID, Entity =&gt; Name);'
`Annotate =&gt; (ID ,ID {, ARG})'
Equivalent to `pragma Annotate (ID, ID {, ARG}, Entity =&gt; Name);'</DOC>
</ASPECT>
<ASPECT id="0" name="Async_Readers" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Async_Readers: 2d.</DOC>
</ASPECT>
<ASPECT id="0" name="Async_Writers" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Async_Writers: 30.</DOC>
</ASPECT>
<ASPECT id="6/3" name="Asynchronous" origin="Ada RM" category="unknown">
<DOC>Remote procedure calls are asynchronous; the caller continues
without waiting for the call to return. See E.4.1.</DOC>
</ASPECT>
<ASPECT id="7/3" name="Atomic" origin="Ada RM" category="unknown">
<DOC>Declare that a type, object, or component is atomic. See C.6.</DOC>
</ASPECT>
<ASPECT id="8/3" name="Atomic_Components" origin="Ada RM" category="unknown">
<DOC>Declare that the components of an array type or object are
atomic. See C.6.</DOC>
</ASPECT>
<ASPECT id="9/3" name="Attach_Handler" origin="Ada RM" category="unknown">
<DOC>Protected procedure is attached to an interrupt. See C.3.1.</DOC>
</ASPECT>
<ASPECT id="10/3" name="Bit_Order" origin="Ada RM" category="unknown">
<DOC>Order of bit numbering in a record_representation_clause. See</DOC>
</ASPECT>
<ASPECT id="15/3" name="CPU" origin="Ada RM" category="unknown">
<DOC>Processor on which a given task should run. See D.16.</DOC>
</ASPECT>
<ASPECT id="11/3" name="Coding" origin="Ada RM" category="unknown">
<DOC>Internal representation of enumeration literals. Specified by
an enumeration_representation_clause, not by an
aspect_specification. See 13.4.</DOC>
</ASPECT>
<ASPECT id="12/3" name="Component_Size" origin="Ada RM" category="unknown">
<DOC>Size in bits of a component of an array type. See 13.3.</DOC>
</ASPECT>
<ASPECT id="0" name="Constant_After_Elaboration" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Constant_After_Elaboration:
42.</DOC>
</ASPECT>
<ASPECT id="13/3" name="Constant_Indexing" origin="Ada RM" category="unknown">
<DOC>Defines function(s) to implement user-defined
indexed_components. See 4.1.6.</DOC>
</ASPECT>
<ASPECT id="0" name="Contract_Cases" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Contract_Cases: 44, the
sequence of clauses being enclosed in parentheses so that syntactically
it is an aggregate.</DOC>
</ASPECT>
<ASPECT id="14/3" name="Convention" origin="Ada RM" category="unknown">
<DOC>Calling convention or other convention used for interfacing to
other languages. See B.1.</DOC>
</ASPECT>
<ASPECT id="16/3" name="Default_Component_Value" origin="Ada RM" category="unknown">
<DOC>Default value for the components of an array-of-scalar
subtype. See 3.6.</DOC>
</ASPECT>
<ASPECT id="0" name="Default_Initial_Condition" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Default_Initial_Condition: 4e.</DOC>
</ASPECT>
<ASPECT id="17/3" name="Default_Iterator" origin="Ada RM" category="unknown">
<DOC>Default iterator to be used in for loops. See 5.5.1.</DOC>
</ASPECT>
<ASPECT id="18/3" name="Default_Storage_Pool" origin="Ada RM" category="unknown">
<DOC>Default storage pool for a generic instance. See 13.11.3.</DOC>
</ASPECT>
<ASPECT id="19/3" name="Default_Value" origin="Ada RM" category="unknown">
<DOC>Default value for a scalar subtype. See 3.5.
19.1/4 Discard_Names
Requests a reduction in storage for names associated with an
entity. See C.5.</DOC>
</ASPECT>
<ASPECT id="0" name="Depends" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Depends: 53.</DOC>
</ASPECT>
<ASPECT id="0" name="Dimension" origin="GNAT RM" category="unknown">
<DOC>The `Dimension' aspect is used to specify the dimensions of a given
subtype of a dimensioned numeric type. The aspect also specifies a
symbol used when doing formatted output of dimensioned quantities. The
syntax is:
with Dimension =&gt;
([Symbol =&gt;] SYMBOL, DIMENSION_VALUE {, DIMENSION_Value})
SYMBOL ::= STRING_LITERAL | CHARACTER_LITERAL
DIMENSION_VALUE ::=
RATIONAL
| others =&gt; RATIONAL
| DISCRETE_CHOICE_LIST =&gt; RATIONAL
RATIONAL ::= [-] NUMERIC_LITERAL [/ NUMERIC_LITERAL]
This aspect can only be applied to a subtype whose parent type has a
`Dimension_System' aspect. The aspect must specify values for all
dimensions of the system. The rational values are the powers of the
corresponding dimensions that are used by the compiler to verify that
physical (numeric) computations are dimensionally consistent. For
example, the computation of a force must result in dimensions (L =&gt; 1,
M =&gt; 1, T =&gt; -2). For further examples of the usage of this aspect,
see package `System.Dim.Mks'. Note that when the dimensioned type is
an integer type, then any dimension value must be an integer literal.</DOC>
</ASPECT>
<ASPECT id="0" name="Dimension_System" origin="GNAT RM" category="unknown">
<DOC>The `Dimension_System' aspect is used to define a system of dimensions
that will be used in subsequent subtype declarations with `Dimension'
aspects that reference this system. The syntax is:
with Dimension_System =&gt; (DIMENSION {, DIMENSION});
DIMENSION ::= ([Unit_Name =&gt;] IDENTIFIER,
[Unit_Symbol =&gt;] SYMBOL,
[Dim_Symbol =&gt;] SYMBOL)
SYMBOL ::= CHARACTER_LITERAL | STRING_LITERAL
This aspect is applied to a type, which must be a numeric derived type
(typically a floating-point type), that will represent values within
the dimension system. Each `DIMENSION' corresponds to one particular
dimension. A maximum of 7 dimensions may be specified. `Unit_Name' is
the name of the dimension (for example `Meter'). `Unit_Symbol' is the
shorthand used for quantities of this dimension (for example `m' for
`Meter'). `Dim_Symbol' gives the identification within the dimension
system (typically this is a single letter, e.g. `L' standing for length
for unit name `Meter'). The `Unit_Symbol' is used in formatted output
of dimensioned quantities. The `Dim_Symbol' is used in error messages
when numeric operations have inconsistent dimensions.
GNAT provides the standard definition of the International MKS system in
the run-time package `System.Dim.Mks'. You can easily define similar
packages for cgs units or British units, and define conversion factors
between values in different systems. The MKS system is characterized by
the following aspect:
type Mks_Type is new Long_Long_Float with
Dimension_System =&gt; (
(Unit_Name =&gt; Meter, Unit_Symbol =&gt; 'm', Dim_Symbol =&gt; 'L'),
(Unit_Name =&gt; Kilogram, Unit_Symbol =&gt; "kg", Dim_Symbol =&gt; 'M'),
(Unit_Name =&gt; Second, Unit_Symbol =&gt; 's', Dim_Symbol =&gt; 'T'),
(Unit_Name =&gt; Ampere, Unit_Symbol =&gt; 'A', Dim_Symbol =&gt; 'I'),
(Unit_Name =&gt; Kelvin, Unit_Symbol =&gt; 'K', Dim_Symbol =&gt; '@'),
(Unit_Name =&gt; Mole, Unit_Symbol =&gt; "mol", Dim_Symbol =&gt; 'N'),
(Unit_Name =&gt; Candela, Unit_Symbol =&gt; "cd", Dim_Symbol =&gt; 'J'));
Note that in the above type definition, we use the `at' symbol (`@') to
represent a theta character (avoiding the use of extended Latin-1
characters in this context).
See section 'Performing Dimensionality Analysis in GNAT' in the GNAT
Users Guide for detailed examples of use of the dimension system.</DOC>
</ASPECT>
<ASPECT id="0" name="Disable_Controlled" origin="GNAT RM" category="unknown">
<DOC>The aspect `Disable_Controlled' is defined for controlled record
types. If active, this aspect causes suppression of all related calls
to `Initialize', `Adjust', and `Finalize'. The intended use is for
conditional compilation, where for example you might want a record to
be controlled or not depending on whether some run-time check is
enabled or suppressed.</DOC>
</ASPECT>
<ASPECT id="20/3" name="Dispatching_Domain" origin="Ada RM" category="unknown">
<DOC>Domain (group of processors) on which a given task should run.
See D.16.1.</DOC>
</ASPECT>
<ASPECT id="21/3" name="Dynamic_Predicate" origin="Ada RM" category="unknown">
<DOC>Condition that must hold true for objects of a given subtype;
the subtype is not static. See 3.2.4.</DOC>
</ASPECT>
<ASPECT id="0" name="Effective_Reads" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Effective_Reads: 59.</DOC>
</ASPECT>
<ASPECT id="0" name="Effective_Writes" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Effective_Writes: 5b.</DOC>
</ASPECT>
<ASPECT id="22/3" name="Elaborate_Body" origin="Ada RM" category="unknown">
<DOC>A given package must have a body, and that body is elaborated
immediately after the declaration. See 10.2.1.
22.1/4 Exclusive_Functions
Specifies mutual exclusion behavior of protected functions in
a protected type. See 9.5.1.</DOC>
</ASPECT>
<ASPECT id="23/3" name="Export" origin="Ada RM" category="unknown">
<DOC>Entity is exported to another language. See B.1.</DOC>
</ASPECT>
<ASPECT id="0" name="Extensions_Visible" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Extensions_Visible: 67.</DOC>
</ASPECT>
<ASPECT id="24/3" name="External_Name" origin="Ada RM" category="unknown">
<DOC>Name used to identify an imported or exported entity. See
B.1.</DOC>
</ASPECT>
<ASPECT id="25/3" name="External_Tag" origin="Ada RM" category="unknown">
<DOC>Unique identifier for a tagged type in streams. See 13.3.</DOC>
</ASPECT>
<ASPECT id="0" name="Favor_Top_Level" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Favor_Top_Level: 6c.</DOC>
</ASPECT>
<ASPECT id="0" name="Ghost" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Ghost: 6f.</DOC>
</ASPECT>
<ASPECT id="0" name="Global" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Global: 71.</DOC>
</ASPECT>
<ASPECT id="26/3" name="Implicit_Dereference" origin="Ada RM" category="unknown">
<DOC>Mechanism for user-defined implicit .all. See 4.1.5.</DOC>
</ASPECT>
<ASPECT id="27/3" name="Import" origin="Ada RM" category="unknown">
<DOC>Entity is imported from another language. See B.1.</DOC>
</ASPECT>
<ASPECT id="28/3" name="Independent" origin="Ada RM" category="unknown">
<DOC>Declare that a type, object, or component is independently
addressable. See C.6.</DOC>
</ASPECT>
<ASPECT id="29/3" name="Independent_Components" origin="Ada RM" category="unknown">
<DOC>Declare that the components of an array or record type, or an
array object, are independently addressable. See C.6.</DOC>
</ASPECT>
<ASPECT id="0" name="Initial_Condition" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Initial_Condition: 7f.</DOC>
</ASPECT>
<ASPECT id="0" name="Initializes" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Initializes: 81.</DOC>
</ASPECT>
<ASPECT id="30/3" name="Inline" origin="Ada RM" category="unknown">
<DOC>For efficiency, Inline calls are requested for a subprogram.
See 6.3.2.</DOC>
</ASPECT>
<ASPECT id="0" name="Inline_Always" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Inline_Always: 84.</DOC>
</ASPECT>
<ASPECT id="31/3" name="Input" origin="Ada RM" category="unknown">
<DOC>Function to read a value from a stream for a given type,
including any bounds and discriminants. See 13.13.2.
31.1/4 Input'Class
Function to read a value from a stream for a the class-wide
type associated with a given type, including any bounds and
discriminants. See 13.13.2.</DOC>
</ASPECT>
<ASPECT id="32/3" name="Interrupt_Handler" origin="Ada RM" category="unknown">
<DOC>Protected procedure may be attached to interrupts. See C.3.1.</DOC>
</ASPECT>
<ASPECT id="33/3" name="Interrupt_Priority" origin="Ada RM" category="unknown">
<DOC>Priority of a task object or type, or priority of a protected
object or type; the priority is in the interrupt range. See
D.1.</DOC>
</ASPECT>
<ASPECT id="0" name="Invariant" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Invariant: 8b. It is a
synonym for the language defined aspect `Type_Invariant' except that it
is separately controllable using pragma `Assertion_Policy'.
3.22 Aspect Invariant'Class
This aspect is equivalent to *note pragma Type_Invariant_Class: 102. It
is a synonym for the language defined aspect `Type_Invariant'Class'
except that it is separately controllable using pragma
`Assertion_Policy'.</DOC>
</ASPECT>
<ASPECT id="0" name="Iterable" origin="GNAT RM" category="unknown">
<DOC>This aspect provides a light-weight mechanism for loops and quantified
expressions over container types, without the overhead imposed by the
tampering checks of standard Ada 2012 iterators. The value of the
aspect is an aggregate with six named components, of which the last
three are optional: `First', `Next', `Has_Element', `Element', `Last',
and `Previous'. When only the first three components are specified,
only the `for .. in' form of iteration over cursors is available. When
`Element' is specified, both this form and the `for .. of' form of
iteration over elements are available. If the last two components are
specified, reverse iterations over the container can be specified
(analogous to what can be done over predefined containers that support
the `Reverse_Iterator' interface). The following is a typical example
of use:
type List is private with
Iterable =&gt; (First =&gt; First_Cursor,
Next =&gt; Advance,
Has_Element =&gt; Cursor_Has_Element,
[Element =&gt; Get_Element]);
* The value denoted by `First' must denote a primitive operation of
the container type that returns a `Cursor', which must a be a type
declared in the container package or visible from it. For example:
function First_Cursor (Cont : Container) return Cursor;
* The value of `Next' is a primitive operation of the container type
that takes both a container and a cursor and yields a cursor. For
example:
function Advance (Cont : Container; Position : Cursor) return Cursor;
* The value of `Has_Element' is a primitive operation of the
container type that takes both a container and a cursor and yields
a boolean. For example:
function Cursor_Has_Element (Cont : Container; Position : Cursor) return Boolean;
* The value of `Element' is a primitive operation of the container
type that takes both a container and a cursor and yields an
`Element_Type', which must be a type declared in the container
package or visible from it. For example:
function Get_Element (Cont : Container; Position : Cursor) return Element_Type;
This aspect is used in the GNAT-defined formal container packages.</DOC>
</ASPECT>
<ASPECT id="34/3" name="Iterator_Element" origin="Ada RM" category="unknown">
<DOC>Element type to be used for user-defined iterators. See</DOC>
</ASPECT>
<ASPECT id="35/3" name="Layout" origin="Ada RM" category="unknown">
<DOC>Layout of record components. Specified by a
record_representation_clause, not by an aspect_specification.
See 13.5.1.</DOC>
</ASPECT>
<ASPECT id="36/3" name="Link_Name" origin="Ada RM" category="unknown">
<DOC>Linker symbol used to identify an imported or exported entity.
See B.1.</DOC>
</ASPECT>
<ASPECT id="0" name="Linker_Section" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Linker_Section: 93.</DOC>
</ASPECT>
<ASPECT id="0" name="Lock_Free" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Lock_Free: 95.</DOC>
</ASPECT>
<ASPECT id="37/3" name="Machine_Radix" origin="Ada RM" category="unknown">
<DOC>Radix (2 or 10) that is used to represent a decimal fixed
point type. See F.1.</DOC>
</ASPECT>
<ASPECT id="0" name="Max_Queue_Length" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Max_Queue_Length: 9d.</DOC>
</ASPECT>
<ASPECT id="0" name="No_Caching" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma No_Caching: 9f.</DOC>
</ASPECT>
<ASPECT id="0" name="No_Elaboration_Code_All" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma No_Elaboration_Code_All: a3.
for a program unit.</DOC>
</ASPECT>
<ASPECT id="0" name="No_Inline" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma No_Inline: a6.</DOC>
</ASPECT>
<ASPECT id="38/3" name="No_Return" origin="Ada RM" category="unknown">
<DOC>A procedure will not return normally. See 6.5.1.</DOC>
</ASPECT>
<ASPECT id="0" name="No_Tagged_Streams" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma No_Tagged_Streams: a9. with an
argument specifying a root tagged type (thus this aspect can only be
applied to such a type).</DOC>
</ASPECT>
<ASPECT id="0" name="Object_Size" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note attribute Object_Size: 143.</DOC>
</ASPECT>
<ASPECT id="0" name="Obsolescent" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Obsolescent: ac. Note that the
evaluation of this aspect happens at the point of occurrence, it is not
delayed until the freeze point.</DOC>
</ASPECT>
<ASPECT id="39/3" name="Output" origin="Ada RM" category="unknown">
<DOC>Procedure to write a value to a stream for a given type,
including any bounds and discriminants. See 13.13.2.
39.1/4 Output'Class
Procedure to write a value to a stream for a the class-wide
type associated with a given type, including any bounds and
discriminants. See 13.13.2.</DOC>
</ASPECT>
<ASPECT id="40/3" name="Pack" origin="Ada RM" category="unknown">
<DOC>Minimize storage when laying out records and arrays. See</DOC>
</ASPECT>
<ASPECT id="0" name="Part_Of" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Part_Of: b4.</DOC>
</ASPECT>
<ASPECT id="0" name="Persistent_BSS" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Persistent_BSS: b7.</DOC>
</ASPECT>
<ASPECT id="41/3" name="Post" origin="Ada RM" category="unknown">
<DOC>Postcondition; a condition that must hold true after a call.
See 6.1.1.</DOC>
</ASPECT>
<ASPECT id="42/3" name="Post'Class" origin="Ada RM" category="unknown">
<DOC>Postcondition inherited on type derivation. See 6.1.1.</DOC>
</ASPECT>
<ASPECT id="43/3" name="Pre" origin="Ada RM" category="unknown">
<DOC>Precondition; a condition that must hold true before a call.
See 6.1.1.</DOC>
</ASPECT>
<ASPECT id="44/3" name="Pre'Class" origin="Ada RM" category="unknown">
<DOC>Precondition inherited on type derivation. See 6.1.1.
44.1/4 Predicate_Failure
Action to be performed when a predicate check fails. See</DOC>
</ASPECT>
<ASPECT id="0" name="Predicate" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Predicate: be. It is thus
similar to the language defined aspects `Dynamic_Predicate' and
`Static_Predicate' except that whether the resulting predicate is
static or dynamic is controlled by the form of the expression. It is
also separately controllable using pragma `Assertion_Policy'.</DOC>
</ASPECT>
<ASPECT id="45/3" name="Preelaborate" origin="Ada RM" category="unknown">
<DOC>Code execution during elaboration is avoided for a given
package. See 10.2.1.</DOC>
</ASPECT>
<ASPECT id="46/3" name="Priority" origin="Ada RM" category="unknown">
<DOC>Priority of a task object or type, or priority of a protected
object or type; the priority is not in the interrupt range.
See D.1.</DOC>
</ASPECT>
<ASPECT id="47/3" name="Pure" origin="Ada RM" category="unknown">
<DOC>Side effects are avoided in the subprograms of a given
package. See 10.2.1.</DOC>
</ASPECT>
<ASPECT id="0" name="Pure_Function" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Pure_Function: ca.</DOC>
</ASPECT>
<ASPECT id="48/3" name="Read" origin="Ada RM" category="unknown">
<DOC>Procedure to read a value from a stream for a given type. See
48.1/4 Read'Class
Procedure to read a value from a stream for the class-wide
type associated with a given type. See 13.13.2.</DOC>
</ASPECT>
<ASPECT id="49/3" name="Record" origin="Ada RM" category="unknown">
<DOC>layout
See Layout. See 13.5.1.</DOC>
</ASPECT>
<ASPECT id="0" name="Refined_Depends" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Refined_Depends: ce.</DOC>
</ASPECT>
<ASPECT id="0" name="Refined_Global" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Refined_Global: d0.</DOC>
</ASPECT>
<ASPECT id="0" name="Refined_Post" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Refined_Post: d2.</DOC>
</ASPECT>
<ASPECT id="0" name="Refined_State" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Refined_State: d4.</DOC>
</ASPECT>
<ASPECT id="50/3" name="Relative_Deadline" origin="Ada RM" category="unknown">
<DOC>Task parameter used in Earliest Deadline First Dispatching.
See D.2.6.</DOC>
</ASPECT>
<ASPECT id="0" name="Relaxed_Initialization" origin="GNAT RM" category="unknown">
<DOC>For the syntax and semantics of this aspect, see the SPARK 2014
Reference Manual, section 6.10.</DOC>
</ASPECT>
<ASPECT id="0" name="Remote_Access_Type" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Remote_Access_Type: d8.</DOC>
</ASPECT>
<ASPECT id="51/3" name="Remote_Call_Interface" origin="Ada RM" category="unknown">
<DOC>Subprograms in a given package may be used in remote procedure
calls. See E.2.3.</DOC>
</ASPECT>
<ASPECT id="52/3" name="Remote_Types" origin="Ada RM" category="unknown">
<DOC>Types in a given package may be used in remote procedure
calls. See E.2.2.</DOC>
</ASPECT>
<ASPECT id="0" name="SPARK_Mode" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma SPARK_Mode: eb. and may be
specified for either or both of the specification and body of a
subprogram or package.</DOC>
</ASPECT>
<ASPECT id="0" name="Scalar_Storage_Order" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to a *note attribute Scalar_Storage_Order:
151.</DOC>
</ASPECT>
<ASPECT id="0" name="Secondary_Stack_Size" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Secondary_Stack_Size: dd.</DOC>
</ASPECT>
<ASPECT id="0" name="Shared" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Shared: e0. and is
thus a synonym for aspect `Atomic'.</DOC>
</ASPECT>
<ASPECT id="53/3" name="Shared_Passive" origin="Ada RM" category="unknown">
<DOC>A given package is used to represent shared memory in a
distributed system. See E.2.1.</DOC>
</ASPECT>
<ASPECT id="0" name="Simple_Storage_Pool" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note attribute Simple_Storage_Pool: e5.</DOC>
</ASPECT>
<ASPECT id="0" name="Simple_Storage_Pool_Type" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma
Simple_Storage_Pool_Type: e3.</DOC>
</ASPECT>
<ASPECT id="54/3" name="Size" origin="Ada RM" category="unknown">
<DOC>Size in bits of an object. See 13.3.</DOC>
</ASPECT>
<ASPECT id="55/3" name="Size" origin="Ada RM" category="unknown">
<DOC>Size in bits of a subtype. See 13.3.</DOC>
</ASPECT>
<ASPECT id="56/3" name="Small" origin="Ada RM" category="unknown">
<DOC>Scale factor for a fixed point type. See 3.5.10.</DOC>
</ASPECT>
<ASPECT id="57/3" name="Static_Predicate" origin="Ada RM" category="unknown">
<DOC>Condition that must hold true for objects of a given subtype;
the subtype may be static. See 3.2.4.</DOC>
</ASPECT>
<ASPECT id="58/3" name="Storage_Pool" origin="Ada RM" category="unknown">
<DOC>Pool of memory from which new will allocate for a given access
type. See 13.11.</DOC>
</ASPECT>
<ASPECT id="59/3" name="Storage_Size" origin="Ada RM" category="unknown">
<DOC>Sets memory size for allocations for an access type. See</DOC>
</ASPECT>
<ASPECT id="60/3" name="Storage_Size" origin="Ada RM" category="unknown">
<DOC>Size in storage elements reserved for a task type or single
task object. See 13.3.</DOC>
</ASPECT>
<ASPECT id="61/3" name="Stream_Size" origin="Ada RM" category="unknown">
<DOC>Size in bits used to represent elementary objects in a stream.
See 13.13.2.</DOC>
</ASPECT>
<ASPECT id="0" name="Suppress_Debug_Info" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Suppress_Debug_Info:
f3.</DOC>
</ASPECT>
<ASPECT id="0" name="Suppress_Initialization" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma
Suppress_Initialization: f7.</DOC>
</ASPECT>
<ASPECT id="62/3" name="Synchronization" origin="Ada RM" category="unknown">
<DOC>Defines whether a given primitive operation of a synchronized
interface must be implemented by an entry or protected
procedure. See 9.5.</DOC>
</ASPECT>
<ASPECT id="0" name="Test_Case" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Test_Case: fa.</DOC>
</ASPECT>
<ASPECT id="1/3" name="This" origin="Ada RM" category="unknown">
<DOC>subclause summarizes the definitions given elsewhere of the
language-defined aspects. Aspects are properties of entities that can be
specified by the Ada program; unless otherwise specified below, aspects can be
specified using an aspect_specification.</DOC>
</ASPECT>
<ASPECT id="0" name="Thread_Local_Storage" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Thread_Local_Storage:
fc.</DOC>
</ASPECT>
<ASPECT id="63/3" name="Type_Invariant" origin="Ada RM" category="unknown">
<DOC>A condition that must hold true for all objects of a type. See</DOC>
</ASPECT>
<ASPECT id="64/3" name="Type_Invariant'Class" origin="Ada RM" category="unknown">
<DOC>A condition that must hold true for all objects in a class of
types. See 7.3.2.</DOC>
</ASPECT>
<ASPECT id="65/3" name="Unchecked_Union" origin="Ada RM" category="unknown">
<DOC>Type is used to interface to a C union type. See B.3.3.</DOC>
</ASPECT>
<ASPECT id="0" name="Universal_Aliasing" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Universal_Aliasing:
106.</DOC>
</ASPECT>
<ASPECT id="0" name="Universal_Data" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note pragma Universal_Data: 108.</DOC>
</ASPECT>
<ASPECT id="0" name="Unmodified" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Unmodified: 10b.</DOC>
</ASPECT>
<ASPECT id="0" name="Unreferenced" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Unreferenced: 10c.
Note that in the case of formal parameters, it is not permitted to have
aspects for a formal parameter, so in this case the pragma form must be
used.</DOC>
</ASPECT>
<ASPECT id="0" name="Unreferenced_Objects" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Unreferenced_Objects:
10e.</DOC>
</ASPECT>
<ASPECT id="0" name="Value_Size" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to *note attribute Value_Size: 160.</DOC>
</ASPECT>
<ASPECT id="66/3" name="Variable_Indexing" origin="Ada RM" category="unknown">
<DOC>Defines function(s) to implement user-defined
indexed_components. See 4.1.6.</DOC>
</ASPECT>
<ASPECT id="67/3" name="Volatile" origin="Ada RM" category="unknown">
<DOC>Declare that a type, object, or component is volatile. See
C.6.</DOC>
</ASPECT>
<ASPECT id="68/3" name="Volatile_Components" origin="Ada RM" category="unknown">
<DOC>Declare that the components of an array type or object are
volatile. See C.6.</DOC>
</ASPECT>
<ASPECT id="0" name="Volatile_Full_Access" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Volatile_Full_Access:
119.</DOC>
</ASPECT>
<ASPECT id="0" name="Volatile_Function" origin="GNAT RM" category="unknown">
<DOC>This boolean aspect is equivalent to *note pragma Volatile_Function:
11b.</DOC>
</ASPECT>
<ASPECT id="0" name="Warnings" origin="GNAT RM" category="unknown">
<DOC>This aspect is equivalent to the two argument form of *note pragma
Warnings: 11d, where the first argument is `ON' or `OFF' and the second
argument is the entity.</DOC>
</ASPECT>
<ASPECT id="69/3" name="Write" origin="Ada RM" category="unknown">
<DOC>Procedure to write a value to a stream for a given type. See
69.1/4 Write'Class
Procedure to write a value to a stream for a the class-wide
type associated with a given type. See 13.13.2.</DOC>
</ASPECT>
<ATTRIBUTE id="0" name="Abort_Signal" origin="GNAT RM" category="variable">
<DOC>`Standard'Abort_Signal' (`Standard' is the only allowed prefix)
provides the entity for the special exception used to signal task abort
or asynchronous transfer of control. Normally this attribute should
only be used in the tasking runtime (it is highly peculiar, and
completely outside the normal semantics of Ada, for a user program to
intercept the abort exception).</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="2" name="Access" origin="Ada RM" category="variable">
<DOC>For a prefix P that denotes a subprogram:
P'Access yields an access value that designates the subprogram
denoted by P. The type of P'Access is an access-to-subprogram
type (S), as determined by the expected type. See 3.10.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="4" name="Access" origin="Ada RM" category="variable">
<DOC>For a prefix X that denotes an aliased view of an object:
X'Access yields an access value that designates the object
denoted by X. The type of X'Access is an access-to-object
type, as determined by the expected type. The expected type
shall be a general access type. See 3.10.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="6/1" name="Address" origin="Ada RM" category="variable">
<DOC>For a prefix X that denotes an object, program unit, or label:
Denotes the address of the first of the storage elements
allocated to X. For a program unit or label, this value refers
to the machine code associated with the corresponding body or
statement. The value of this attribute is of type
System.Address. See 13.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Address_Size" origin="GNAT RM" category="variable">
<DOC>`Standard'Address_Size' (`Standard' is the only allowed prefix) is a
static constant giving the number of bits in an `Address'. It is the
same value as System.Address'Size, but has the advantage of being
static, while a direct reference to System.Address'Size is nonstatic
because Address is a private type.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="8" name="Adjacent" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
S'Adjacent denotes a function with the following
specification:
function S'Adjacent (X, Towards : T)
return T
If Towards = X, the function yields X; otherwise, it yields
the machine number of the type T adjacent to X in the
direction of Towards, if that machine number exists. If the
result would be outside the base range of S, Constraint_Error
is raised. When T'Signed_Zeros is True, a zero result has the
sign of X. When Towards is zero, its sign has no bearing on
the result. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="12" name="Aft" origin="Ada RM" category="variable">
<DOC>For every fixed point subtype S:
S'Aft yields the number of decimal digits needed after the
decimal point to accommodate the delta of the subtype S,
unless the delta of the subtype S is greater than 0.1, in
which case the attribute yields the value one. (S'Aft is the
smallest positive integer N for which (10**N)*S'Delta is
greater than or equal to one.) The value of this attribute is
of the type universal_integer. See 3.5.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="13.1/2" name="Alignment" origin="Ada RM" category="variable">
<DOC>For every subtype S:
The value of this attribute is of type universal_integer, and
nonnegative.
For an object X of subtype S, if S'Alignment is not zero, then
X'Alignment is a nonzero integral multiple of S'Alignment
unless specified otherwise by a representation item. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="14/1" name="Alignment" origin="Ada RM" category="variable">
<DOC>For a prefix X that denotes an object:
The value of this attribute is of type universal_integer, and
nonnegative; zero means that the object is not necessarily
aligned on a storage element boundary. If X'Alignment is not
zero, then X is aligned on a storage unit boundary and
X'Address is an integral multiple of X'Alignment (that is, the
Address modulo the Alignment is zero).</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Asm_Input" origin="GNAT RM" category="function">
<DOC>The `Asm_Input' attribute denotes a function that takes two parameters.
The first is a string, the second is an expression of the type
designated by the prefix. The first (string) argument is required to
be a static expression, and is the constraint for the parameter, (e.g.,
what kind of register is required). The second argument is the value
to be used as the input argument. The possible values for the constant
are the same as those used in the RTL, and are dependent on the
configuration file used to built the GCC back end. *note Machine Code
Insertions: 169.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Asm_Output" origin="GNAT RM" category="function">
<DOC>The `Asm_Output' attribute denotes a function that takes two
parameters. The first is a string, the second is the name of a variable
of the type designated by the attribute prefix. The first (string)
argument is required to be a static expression and designates the
constraint for the parameter (e.g., what kind of register is required).
The second argument is the variable to be updated with the result. The
possible values for constraint are the same as those used in the RTL,
and are dependent on the configuration file used to build the GCC back
end. If there are no output operands, then this argument may either be
omitted, or explicitly given as `No_Output_Operands'. *note Machine
Code Insertions: 169.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Atomic_Always_Lock_Free" origin="GNAT RM" category="unknown">
<DOC>The prefix of the `Atomic_Always_Lock_Free' attribute is a type. The
result is a Boolean value which is True if the type has discriminants,
and False otherwise. The result indicate whether atomic operations are
supported by the target for the given type.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="17" name="Base" origin="Ada RM" category="type">
<DOC>For every scalar subtype S:
S'Base denotes an unconstrained subtype of the type of S. This
unconstrained subtype is called the base subtype of the type.
See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Bit" origin="GNAT RM" category="variable">
<DOC>`obj'Bit', where `obj' is any object, yields the bit offset within the
storage unit (byte) that contains the first bit of storage allocated
for the object. The value of this attribute is of the type
`universal_integer' and is always a nonnegative number smaller than
`System.Storage_Unit'.
For an object that is a variable or a constant allocated in a register,
the value is zero. (The use of this attribute does not force the
allocation of a variable to memory).
For an object that is a formal parameter, this attribute applies to
either the matching actual parameter or to a copy of the matching
actual parameter.
For an access object the value is zero. Note that `obj.all'Bit' is
subject to an `Access_Check' for the designated object. Similarly for
a record component `X.C'Bit' is subject to a discriminant check and
`X(I).Bit' and `X(I1..I2)'Bit' are subject to index checks.
This attribute is designed to be compatible with the DEC Ada 83
definition and implementation of the `Bit' attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="19" name="Bit_Order" origin="Ada RM" category="variable">
<DOC>For every specific record subtype S:
Denotes the bit ordering for the type of S. The value of this
attribute is of type System.Bit_Order. See 13.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Bit_Position" origin="GNAT RM" category="variable">
<DOC>`R.C'Bit_Position', where `R' is a record object and `C' is one of the
fields of the record type, yields the bit offset within the record
contains the first bit of storage allocated for the object. The value
of this attribute is of the type `universal_integer'. The value
depends only on the field `C' and is independent of the alignment of
the containing record `R'.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="21/1" name="Body_Version" origin="Ada RM" category="variable">
<DOC>For a prefix P that statically denotes a program unit:
Yields a value of the predefined type String that identifies
the version of the compilation unit that contains the body
(but not any subunits) of the program unit. See E.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="23" name="Callable" origin="Ada RM" category="variable">
<DOC>For a prefix T that is of a task type (after any implicit
dereference):
Yields the value True when the task denoted by T is callable,
and False otherwise; See 9.9.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="25" name="Caller" origin="Ada RM" category="variable">
<DOC>For a prefix E that denotes an entry_declaration:
Yields a value of the type Task_Id that identifies the task
whose call is now being serviced. Use of this attribute is
allowed only inside an accept_statement, or entry_body after
the entry_barrier, corresponding to the entry_declaration
denoted by E. See C.7.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="27" name="Ceiling" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
S'Ceiling denotes a function with the following specification:
function S'Ceiling (X : T)
return T
The function yields the value Ceiling(X), i.e., the smallest
(most negative) integral value greater than or equal to X.
When X is zero, the result has the sign of X; a zero result
otherwise has a negative sign when S'Signed_Zeros is True. See
A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="31" name="Class" origin="Ada RM" category="unknown">
<DOC>For every subtype S of a tagged type T (specific or
class-wide):
S'Class denotes a subtype of the class-wide type (called
T'Class in this International Standard) for the class rooted
at T (or if S already denotes a class-wide subtype, then
S'Class is the same as S).
S'Class is unconstrained. However, if S is constrained, then
the values of S'Class are only those that when converted to
the type T belong to S. See 3.9.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="34" name="Class" origin="Ada RM" category="unknown">
<DOC>For every subtype S of an untagged private type whose full
view is tagged:
Denotes the class-wide subtype corresponding to the full view
of S. This attribute is allowed only from the beginning of the
private part in which the full view is declared, until the
declaration of the full view. After the full view, the Class
attribute of the full view can be used. See 7.3.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="92" name="Class'Input" origin="Ada RM" category="function">
<DOC>For every subtype S'Class of a class-wide type T'Class:
S'Class'Input denotes a function with the following
specification:
function S'Class'Input(
Stream : not null access Ada.Streams.Root_Stream_Type'Class)
return T'Class
First reads the external tag from Stream and determines the
corresponding internal tag (by calling
Tags.Descendant_Tag(String'Input(Stream), S'Tag) which might
raise Tag_Error - see 3.9) and then dispatches to the
subprogram denoted by the Input attribute of the specific type
identified by the internal tag; returns that result. If the
specific type identified by the internal tag is abstract,
Constraint_Error is raised. See 13.13.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="165" name="Class'Output" origin="Ada RM" category="procedure">
<DOC>For every subtype S'Class of a class-wide type T'Class:
S'Class'Output denotes a procedure with the following
specification:
procedure S'Class'Output(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T'Class)
First writes the external tag of Item to Stream (by calling
String'Output(Stream, Tags.External_Tag(Item'Tag)) - see 3.9)
and then dispatches to the subprogram denoted by the Output
attribute of the specific type identified by the tag.
Tag_Error is raised if the tag of Item identifies a type
declared at an accessibility level deeper than that of S. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="191" name="Class'Read" origin="Ada RM" category="procedure">
<DOC>For every subtype S'Class of a class-wide type T'Class:
S'Class'Read denotes a procedure with the following
specification:
procedure S'Class'Read(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : out T'Class)
Dispatches to the subprogram denoted by the Read attribute of
the specific type identified by the tag of Item. See 13.13.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="282" name="Class'Write" origin="Ada RM" category="procedure">
<DOC>For every subtype S'Class of a class-wide type T'Class:
S'Class'Write denotes a procedure with the following
specification:
procedure S'Class'Write(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T'Class)
Dispatches to the subprogram denoted by the Write attribute of
the specific type identified by the tag of Item. See 13.13.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Code_Address" origin="GNAT RM" category="variable">
<DOC>The `'Address' attribute may be applied to subprograms in Ada 95 and
Ada 2005, but the intended effect seems to be to provide an address
value which can be used to call the subprogram by means of an address
clause as in the following example:
procedure K is ...
procedure L;
for L'Address use K'Address;
pragma Import (Ada, L);
A call to `L' is then expected to result in a call to `K'. In Ada 83,
where there were no access-to-subprogram values, this was a common
work-around for getting the effect of an indirect call. GNAT
implements the above use of `Address' and the technique illustrated by
the example code works correctly.
However, for some purposes, it is useful to have the address of the
start of the generated code for the subprogram. On some architectures,
this is not necessarily the same as the `Address' value described above.
For example, the `Address' value may reference a subprogram descriptor
rather than the subprogram itself.
The `'Code_Address' attribute, which can only be applied to subprogram
entities, always returns the address of the start of the generated code
of the specified subprogram, which may or may not be the same value as
is returned by the corresponding `'Address' attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Compiler_Version" origin="GNAT RM" category="variable">
<DOC>`Standard'Compiler_Version' (`Standard' is the only allowed prefix)
yields a static string identifying the version of the compiler being
used to compile the unit containing the attribute reference.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="36/1" name="Component_Size" origin="Ada RM" category="variable">
<DOC>For a prefix X that denotes an array subtype or array object
(after any implicit dereference):
Denotes the size in bits of components of the type of X. The
value of this attribute is of type universal_integer. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="38" name="Compose" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Compose denotes a function with the following specification:
function S'Compose (Fraction : T;
Exponent : universal_integer)
return T
Let v be the value Fraction x T'Machine_Radix(Exponent-k),
where k is the normalized exponent of Fraction. If v is a
machine number of the type T, or if |v| &gt;= T'Model_Small, the
function yields v; otherwise, it yields either one of the
machine numbers of the type T adjacent to v. Constraint_Error
is optionally raised if v is outside the base range of S. A
zero result has the sign of Fraction when S'Signed_Zeros is
True. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Constrained" origin="GNAT RM" category="variable">
<DOC>In addition to the usage of this attribute in the Ada RM, GNAT also
permits the use of the `'Constrained' attribute in a generic template
for any type, including types without discriminants. The value of this
attribute in the generic instance when applied to a scalar type or a
record type without discriminants is always `True'. This usage is
compatible with older Ada compilers, including notably DEC Ada.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="42" name="Constrained" origin="Ada RM" category="variable">
<DOC>For a prefix A that is of a discriminated type (after any
implicit dereference):
Yields the value True if A denotes a constant, a value, a
tagged object, or a constrained variable, and False otherwise.
See 3.7.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="44" name="Copy_Sign" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Copy_Sign denotes a function with the following
specification:
function S'Copy_Sign (Value, Sign : T)
return T
If the value of Value is nonzero, the function yields a result
whose magnitude is that of Value and whose sign is that of
Sign; otherwise, it yields the value zero. Constraint_Error is
optionally raised if the result is outside the base range of
S. A zero result has the sign of Sign when S'Signed_Zeros is
True. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="48" name="Count" origin="Ada RM" category="variable">
<DOC>For a prefix E that denotes an entry of a task or protected
unit:
Yields the number of calls presently queued on the entry E of
the current instance of the unit. The value of this attribute
is of the type universal_integer. See 9.9.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Default_Bit_Order" origin="GNAT RM" category="variable">
<DOC>`Standard'Default_Bit_Order' (`Standard' is the only permissible
prefix), provides the value `System.Default_Bit_Order' as a `Pos' value
(0 for `High_Order_First', 1 for `Low_Order_First'). This is used to
construct the definition of `Default_Bit_Order' in package `System'.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Default_Scalar_Storage_Order" origin="GNAT RM" category="unknown">
<DOC>`Standard'Default_Scalar_Storage_Order' (`Standard' is the only
permissible prefix), provides the current value of the default scalar
storage order (as specified using pragma
`Default_Scalar_Storage_Order', or equal to `Default_Bit_Order' if
unspecified) as a `System.Bit_Order' value. This is a static attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="50/1" name="Definite" origin="Ada RM" category="variable">
<DOC>For a prefix S that denotes a formal indefinite subtype:
S'Definite yields True if the actual subtype corresponding to
S is definite; otherwise, it yields False. The value of this
attribute is of the predefined type Boolean. See 12.5.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="52" name="Delta" origin="Ada RM" category="variable">
<DOC>For every fixed point subtype S:
S'Delta denotes the delta of the fixed point subtype S. The
value of this attribute is of the type universal_real. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="54" name="Denorm" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the value True if every value expressible in the form
+- mantissa x T'Machine_Radix(T'Machine_Emin)
where mantissa is a nonzero T'Machine_Mantissa-digit fraction
in the number base T'Machine_Radix, the first digit of which
is zero, is a machine number (see 3.5.7) of the type T; yields
the value False otherwise. The value of this attribute is of
the predefined type Boolean. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Deref" origin="GNAT RM" category="variable">
<DOC>The attribute `typ'Deref(expr)' where `expr' is of type
`System.Address' yields the variable of type `typ' that is located at
the given address. It is similar to `(totyp (expr).all)', where `totyp'
is an unchecked conversion from address to a named access-to-`typ'
type, except that it yields a variable, so it can be used on the left
side of an assignment.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Descriptor_Size" origin="GNAT RM" category="unknown">
<DOC>Nonstatic attribute `Descriptor_Size' returns the size in bits of the
descriptor allocated for a type. The result is non-zero only for
unconstrained array types and the returned value is of type universal
integer. In GNAT, an array descriptor contains bounds information and
is located immediately before the first element of the array.
type Unconstr_Array is array (Short_Short_Integer range &lt;&gt;) of Positive;
Put_Line ("Descriptor size = " &amp; Unconstr_Array'Descriptor_Size'Img);
The attribute takes into account any padding due to the alignment of the
component type. In the example above, the descriptor contains two values
of type `Short_Short_Integer' representing the low and high bound. But,
since `Positive' has an alignment of 4, the size of the descriptor is
`2 * Short_Short_Integer'Size' rounded up to the next multiple of 32,
which yields a size of 32 bits, i.e. including 16 bits of padding.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="56" name="Digits" origin="Ada RM" category="variable">
<DOC>For every floating point subtype S:
S'Digits denotes the requested decimal precision for the
subtype S. The value of this attribute is of the type
universal_integer. See 3.5.8.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="58" name="Digits" origin="Ada RM" category="variable">
<DOC>For every decimal fixed point subtype S:
S'Digits denotes the digits of the decimal fixed point subtype
S, which corresponds to the number of decimal digits that are
representable in objects of the subtype. The value of this
attribute is of the type universal_integer. See 3.5.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Elab_Body" origin="GNAT RM" category="procedure">
<DOC>This attribute can only be applied to a program unit name. It returns
the entity for the corresponding elaboration procedure for elaborating
the body of the referenced unit. This is used in the main generated
elaboration procedure by the binder and is not normally used in any
other context. However, there may be specialized situations in which it
is useful to be able to call this elaboration procedure from Ada code,
e.g., if it is necessary to do selective re-elaboration to fix some
error.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Elab_Spec" origin="GNAT RM" category="procedure">
<DOC>This attribute can only be applied to a program unit name. It returns
the entity for the corresponding elaboration procedure for elaborating
the spec of the referenced unit. This is used in the main generated
elaboration procedure by the binder and is not normally used in any
other context. However, there may be specialized situations in which
it is useful to be able to call this elaboration procedure from Ada
code, e.g., if it is necessary to do selective re-elaboration to fix
some error.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Elab_Subp_Body" origin="GNAT RM" category="unknown">
<DOC>This attribute can only be applied to a library level subprogram name
and is only allowed in CodePeer mode. It returns the entity for the
corresponding elaboration procedure for elaborating the body of the
referenced subprogram unit. This is used in the main generated
elaboration procedure by the binder in CodePeer mode only and is
unrecognized otherwise.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Elaborated" origin="GNAT RM" category="variable">
<DOC>The prefix of the `'Elaborated' attribute must be a unit name. The
value is a Boolean which indicates whether or not the given unit has
been elaborated. This attribute is primarily intended for internal use
by the generated code for dynamic elaboration checking, but it can also
be used in user programs. The value will always be True once
elaboration of all units has been completed. An exception is for units
which need no elaboration, the value is always False for such units.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Emax" origin="GNAT RM" category="variable">
<DOC>The `Emax' attribute is provided for compatibility with Ada 83. See
the Ada 83 reference manual for an exact description of the semantics of
this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Enabled" origin="GNAT RM" category="variable">
<DOC>The `Enabled' attribute allows an application program to check at
compile time to see if the designated check is currently enabled. The
prefix is a simple identifier, referencing any predefined check name
(other than `All_Checks') or a check name introduced by pragma
Check_Name. If no argument is given for the attribute, the check is for
the general state of the check, if an argument is given, then it is an
entity name, and the check indicates whether an `Suppress' or
`Unsuppress' has been given naming the entity (if not, then the
argument is ignored).
Note that instantiations inherit the check status at the point of the
instantiation, so a useful idiom is to have a library package that
introduces a check name with `pragma Check_Name', and then contains
generic packages or subprograms which use the `Enabled' attribute to
see if the check is enabled. A user of this package can then issue a
`pragma Suppress' or `pragma Unsuppress' before instantiating the
package or subprogram, controlling whether the check will be present.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Enum_Rep" origin="GNAT RM" category="function">
<DOC>Note that this attribute is now standard in Ada 202x and is available
as an implementation defined attribute for earlier Ada versions.
For every enumeration subtype `S', `S'Enum_Rep' denotes a function with
the following spec:
function S'Enum_Rep (Arg : S'Base) return &lt;Universal_Integer&gt;;
It is also allowable to apply `Enum_Rep' directly to an object of an
enumeration type or to a non-overloaded enumeration literal. In this
case `S'Enum_Rep' is equivalent to `typ'Enum_Rep(S)' where `typ' is the
type of the enumeration literal or object.
The function returns the representation value for the given enumeration
value. This will be equal to value of the `Pos' attribute in the
absence of an enumeration representation clause. This is a static
attribute (i.e., the result is static if the argument is static).
`S'Enum_Rep' can also be used with integer types and objects, in which
case it simply returns the integer value. The reason for this is to
allow it to be used for `(&lt;&gt;)' discrete formal arguments in a generic
unit that can be instantiated with either enumeration types or integer
types. Note that if `Enum_Rep' is used on a modular type whose upper
bound exceeds the upper bound of the largest signed integer type, and
the argument is a variable, so that the universal integer calculation
is done at run time, then the call to `Enum_Rep' may raise
`Constraint_Error'.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Enum_Val" origin="GNAT RM" category="function">
<DOC>Note that this attribute is now standard in Ada 202x and is available
as an implementation defined attribute for earlier Ada versions.
For every enumeration subtype `S', `S'Enum_Val' denotes a function with
the following spec:
function S'Enum_Val (Arg : &lt;Universal_Integer&gt;) return S'Base;
The function returns the enumeration value whose representation matches
the argument, or raises Constraint_Error if no enumeration literal of
the type has the matching value. This will be equal to value of the
`Val' attribute in the absence of an enumeration representation clause.
This is a static attribute (i.e., the result is static if the argument
is static).</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Epsilon" origin="GNAT RM" category="variable">
<DOC>The `Epsilon' attribute is provided for compatibility with Ada 83. See
the Ada 83 reference manual for an exact description of the semantics of
this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="60" name="Exponent" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Exponent denotes a function with the following
specification:
function S'Exponent (X : T)
return universal_integer
The function yields the normalized exponent of X. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="64" name="External_Tag" origin="Ada RM" category="variable">
<DOC>For every subtype S of a tagged type T (specific or
class-wide):
S'External_Tag denotes an external string representation for
S'Tag; it is of the predefined type String. External_Tag may
be specified for a specific tagged type via an
attribute_definition_clause; the expression of such a clause
shall be static. The default external tag representation is
implementation defined. See 13.13.2. See 13.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Fast_Math" origin="GNAT RM" category="unknown">
<DOC>`Standard'Fast_Math' (`Standard' is the only allowed prefix) yields a
static Boolean value that is True if pragma `Fast_Math' is active, and
False otherwise.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Finalization_Size" origin="GNAT RM" category="variable">
<DOC>The prefix of attribute `Finalization_Size' must be an object or a
non-class-wide type. This attribute returns the size of any hidden data
reserved by the compiler to handle finalization-related actions. The
type of the attribute is `universal_integer'.
`Finalization_Size' yields a value of zero for a type with no controlled
parts, an object whose type has no controlled parts, or an object of a
class-wide type whose tag denotes a type with no controlled parts.
Note that only heap-allocated objects contain finalization data.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="66/1" name="First" origin="Ada RM" category="variable">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'First denotes the lower bound of the first index range; its
type is the corresponding index type. See 3.6.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="68" name="First" origin="Ada RM" category="variable">
<DOC>For every scalar subtype S:
S'First denotes the lower bound of the range of S. The value
of this attribute is of the type of S. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="70/1" name="First(N)" origin="Ada RM" category="variable">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'First(N) denotes the lower bound of the N-th index range;
its type is the corresponding index type. See 3.6.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="72" name="First_Bit" origin="Ada RM" category="variable">
<DOC>For a component C of a composite, non-array object R:
If the nondefault bit ordering applies to the composite type,
and if a component_clause specifies the placement of C,
denotes the value given for the first_bit of the
component_clause; otherwise, denotes the offset, from the
start of the first of the storage elements occupied by C, of
the first bit occupied by C. This offset is measured in bits.
The first bit of a storage element is numbered zero. The value
of this attribute is of the type universal_integer. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="73.1/4" name="First_Valid" origin="Ada RM" category="unknown">
<DOC>For every static discrete subtype S for which there exists at
least one value belonging to S that satisfies the predicates
of S:
S'First_Valid denotes the smallest value that belongs to S and
satisfies the predicates of S. The value of this attribute is
of the type of S. See 3.5.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Fixed_Value" origin="GNAT RM" category="function">
<DOC>For every fixed-point type `S', `S'Fixed_Value' denotes a function with
the following specification:
function S'Fixed_Value (Arg : &lt;Universal_Integer&gt;) return S;
The value returned is the fixed-point value `V' such that:
V = Arg * S'Small
The effect is thus similar to first converting the argument to the
integer type used to represent `S', and then doing an unchecked
conversion to the fixed-point type. The difference is that there are
full range checks, to ensure that the result is in range. This
attribute is primarily intended for use in implementation of the
input-output functions for fixed-point values.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="74" name="Floor" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Floor denotes a function with the following specification:
function S'Floor (X : T)
return T
The function yields the value Floor(X), i.e., the largest
(most positive) integral value less than or equal to X. When X
is zero, the result has the sign of X; a zero result otherwise
has a positive sign. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="78" name="Fore" origin="Ada RM" category="variable">
<DOC>For every fixed point subtype S:
S'Fore yields the minimum number of characters needed before
the decimal point for the decimal representation of any value
of the subtype S, assuming that the representation does not
include an exponent, but includes a one-character prefix that
is either a minus sign or a space. (This minimum number does
not include superfluous zeros or underlines, and is at least
) The value of this attribute is of the type
universal_integer. See 3.5.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="80" name="Fraction" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Fraction denotes a function with the following
specification:
function S'Fraction (X : T)
return T
The function yields the value X x T'Machine_Radix(-k), where k
is the normalized exponent of X. A zero result, which can only
occur when X is zero, has the sign of X. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="From_Any" origin="GNAT RM" category="unknown">
<DOC>This internal attribute is used for the generation of remote subprogram
stubs in the context of the Distributed Systems Annex.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Has_Access_Values" origin="GNAT RM" category="variable">
<DOC>The prefix of the `Has_Access_Values' attribute is a type. The result
is a Boolean value which is True if the is an access type, or is a
composite type with a component (at any nesting depth) that is an
access type, and is False otherwise. The intended use of this
attribute is in conjunction with generic definitions. If the attribute
is applied to a generic private type, it indicates whether or not the
corresponding actual type has access values.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Has_Discriminants" origin="GNAT RM" category="variable">
<DOC>The prefix of the `Has_Discriminants' attribute is a type. The result
is a Boolean value which is True if the type has discriminants, and
False otherwise. The intended use of this attribute is in conjunction
with generic definitions. If the attribute is applied to a generic
private type, it indicates whether or not the corresponding actual type
has discriminants.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="83.1/3" name="Has_Same_Storage" origin="Ada RM" category="unknown">
<DOC>For a prefix X that denotes an object:
X'Has_Same_Storage denotes a function with the following
specification:
function X'Has_Same_Storage (Arg : any_type)
return Boolean
The actual parameter shall be a name that denotes an object.
The object denoted by the actual parameter can be of any type.
This function evaluates the names of the objects involved. It
returns True if the representation of the object denoted by
the actual parameter occupies exactly the same bits as the
representation of the object denoted by X and the objects
occupy at least one bit; otherwise, it returns False. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="84/1" name="Identity" origin="Ada RM" category="variable">
<DOC>For a prefix E that denotes an exception:
E'Identity returns the unique identity of the exception. The
type of this attribute is Exception_Id. See 11.4.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="86" name="Identity" origin="Ada RM" category="variable">
<DOC>For a prefix T that is of a task type (after any implicit
dereference):
Yields a value of the type Task_Id that identifies the task
denoted by T. See C.7.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="88" name="Image" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Image denotes a function with the following specification:
function S'Image(Arg : S'Base)
return String
The function returns an image of the value of Arg as a String.
See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="91.1/4" name="Image" origin="Ada RM" category="function">
<DOC>For a prefix X that denotes an object of a scalar type (after
any implicit dereference):
X'Image denotes the result of calling function S'Image with
Arg being X, where S is the nominal subtype of X. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Img" origin="GNAT RM" category="function">
<DOC>The `Img' attribute differs from `Image' in that, while both can be
applied directly to an object, `Img' cannot be applied to types.
Example usage of the attribute:
Put_Line ("X = " &amp; X'Img);
which has the same meaning as the more verbose:
Put_Line ("X = " &amp; T'Image (X));
where `T' is the (sub)type of the object `X'.
Note that technically, in analogy to `Image', `X'Img' returns a
parameterless function that returns the appropriate string when called.
This means that `X'Img' can be renamed as a function-returning-string,
or used in an instantiation as a function parameter.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Initialized" origin="GNAT RM" category="variable">
<DOC>For the syntax and semantics of this attribute, see the SPARK 2014
Reference Manual, section 6.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="96" name="Input" origin="Ada RM" category="function">
<DOC>For every subtype S of a specific type T:
S'Input denotes a function with the following specification:
function S'Input(
Stream : not null access Ada.Streams.Root_Stream_Type'Class)
return T
S'Input reads and returns one value from Stream, using any
bounds or discriminants written by a corresponding S'Output to
determine how much to read. See 13.13.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Integer_Value" origin="GNAT RM" category="function">
<DOC>For every integer type `S', `S'Integer_Value' denotes a function with
the following spec:
function S'Integer_Value (Arg : &lt;Universal_Fixed&gt;) return S;
The value returned is the integer value `V', such that:
Arg = V * T'Small
where `T' is the type of `Arg'. The effect is thus similar to first
doing an unchecked conversion from the fixed-point type to its
corresponding implementation type, and then converting the result to
the target integer type. The difference is that there are full range
checks, to ensure that the result is in range. This attribute is
primarily intended for use in implementation of the standard
input-output functions for fixed-point values.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Invalid_Value" origin="GNAT RM" category="variable">
<DOC>For every scalar type S, S'Invalid_Value returns an undefined value of
the type. If possible this value is an invalid representation for the
type. The value returned is identical to the value used to initialize
an otherwise uninitialized value of the type if pragma
Initialize_Scalars is used, including the ability to modify the value
with the binder -Sxx flag and relevant environment variables at run
time.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Iterable" origin="GNAT RM" category="unknown">
<DOC>Equivalent to Aspect Iterable.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Large" origin="GNAT RM" category="variable">
<DOC>The `Large' attribute is provided for compatibility with Ada 83. See
the Ada 83 reference manual for an exact description of the semantics of
this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="100/1" name="Last" origin="Ada RM" category="variable">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'Last denotes the upper bound of the first index range; its
type is the corresponding index type. See 3.6.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="102" name="Last" origin="Ada RM" category="variable">
<DOC>For every scalar subtype S:
S'Last denotes the upper bound of the range of S. The value of
this attribute is of the type of S. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="104/1" name="Last(N)" origin="Ada RM" category="variable">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'Last(N) denotes the upper bound of the N-th index range; its
type is the corresponding index type. See 3.6.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="106" name="Last_Bit" origin="Ada RM" category="variable">
<DOC>For a component C of a composite, non-array object R:
If the nondefault bit ordering applies to the composite type,
and if a component_clause specifies the placement of C,
denotes the value given for the last_bit of the
component_clause; otherwise, denotes the offset, from the
start of the first of the storage elements occupied by C, of
the last bit occupied by C. This offset is measured in bits.
The value of this attribute is of the type universal_integer.
See 13.5.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="107.1/4" name="Last_Valid" origin="Ada RM" category="unknown">
<DOC>For every static discrete subtype S for which there exists at
least one value belonging to S that satisfies the predicates
of S:
S'Last_Valid denotes the largest value that belongs to S and
satisfies the predicates of S. The value of this attribute is
of the type of S. See 3.5.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="108" name="Leading_Part" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Leading_Part denotes a function with the following
specification:
function S'Leading_Part (X : T;
Radix_Digits : universal_integer)
return T
Let v be the value T'Machine_Radix(k-Radix_Digits), where k is
the normalized exponent of X. The function yields the value
* Floor(X/v) x v, when X is nonnegative and Radix_Digits is
positive;
* Ceiling(X/v) x v, when X is negative and Radix_Digits is
positive.
Constraint_Error is raised when Radix_Digits is zero or
negative. A zero result, which can only occur when X is zero,
has the sign of X. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="115/1" name="Length" origin="Ada RM" category="variable">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'Length denotes the number of values of the first index range
(zero for a null range); its type is universal_integer. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="117/1" name="Length(N)" origin="Ada RM" category="variable">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'Length(N) denotes the number of values of the N-th index
range (zero for a null range); its type is universal_integer.
See 3.6.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Library_Level" origin="GNAT RM" category="unknown">
<DOC>`P'Library_Level', where P is an entity name, returns a Boolean value
which is True if the entity is declared at the library level, and False
otherwise. Note that within a generic instantition, the name of the
generic unit denotes the instance, which means that this attribute can
be used to test if a generic is instantiated at the library level, as
shown in this example:
generic
package Gen is
pragma Compile_Time_Error
(not Gen'Library_Level,
"Gen can only be instantiated at library level");
end Gen;</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Lock_Free" origin="GNAT RM" category="unknown">
<DOC>`P'Lock_Free', where P is a protected object, returns True if a pragma
`Lock_Free' applies to P.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Loop_Entry" origin="GNAT RM" category="unknown">
<DOC>Syntax:
X'Loop_Entry [(loop_name)]
The `Loop_Entry' attribute is used to refer to the value that an
expression had upon entry to a given loop in much the same way that the
`Old' attribute in a subprogram postcondition can be used to refer to
the value an expression had upon entry to the subprogram. The relevant
loop is either identified by the given loop name, or it is the
innermost enclosing loop when no loop name is given.
A `Loop_Entry' attribute can only occur within a `Loop_Variant' or
`Loop_Invariant' pragma. A common use of `Loop_Entry' is to compare the
current value of objects with their initial value at loop entry, in a
`Loop_Invariant' pragma.
The effect of using `X'Loop_Entry' is the same as declaring a constant
initialized with the initial value of `X' at loop entry. This copy is
not performed if the loop is not entered, or if the corresponding
pragmas are ignored or disabled.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="119" name="Machine" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Machine denotes a function with the following specification:
function S'Machine (X : T)
return T
If X is a machine number of the type T, the function yields X;
otherwise, it yields the value obtained by rounding or
truncating X to either one of the adjacent machine numbers of
the type T. Constraint_Error is raised if rounding or
truncating X to the precision of the machine numbers results
in a value outside the base range of S. A zero result has the
sign of X when S'Signed_Zeros is True. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="123" name="Machine_Emax" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the largest (most positive) value of exponent such that
every value expressible in the canonical form (for the type
T), having a mantissa of T'Machine_Mantissa digits, is a
machine number (see 3.5.7) of the type T. This attribute
yields a value of the type universal_integer. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="125" name="Machine_Emin" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the smallest (most negative) value of exponent such
that every value expressible in the canonical form (for the
type T), having a mantissa of T'Machine_Mantissa digits, is a
machine number (see 3.5.7) of the type T. This attribute
yields a value of the type universal_integer. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="127" name="Machine_Mantissa" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the largest value of p such that every value
expressible in the canonical form (for the type T), having a
p-digit mantissa and an exponent between T'Machine_Emin and
T'Machine_Emax, is a machine number (see 3.5.7) of the type T.
This attribute yields a value of the type universal_integer.
See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="129" name="Machine_Overflows" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the value True if overflow and divide-by-zero are
detected and reported by raising Constraint_Error for every
predefined operation that yields a result of the type T;
yields the value False otherwise. The value of this attribute
is of the predefined type Boolean. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="131" name="Machine_Overflows" origin="Ada RM" category="variable">
<DOC>For every subtype S of a fixed point type T:
Yields the value True if overflow and divide-by-zero are
detected and reported by raising Constraint_Error for every
predefined operation that yields a result of the type T;
yields the value False otherwise. The value of this attribute
is of the predefined type Boolean. See A.5.4.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="133" name="Machine_Radix" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the radix of the hardware representation of the type T.
The value of this attribute is of the type universal_integer.
See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="135" name="Machine_Radix" origin="Ada RM" category="variable">
<DOC>For every subtype S of a fixed point type T:
Yields the radix of the hardware representation of the type T.
The value of this attribute is of the type universal_integer.
See A.5.4.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="136.1/2" name="Machine_Rounding" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Machine_Rounding denotes a function with the following
specification:
function S'Machine_Rounding (X : T)
return T
The function yields the integral value nearest to X. If X lies
exactly halfway between two integers, one of those integers is
returned, but which of them is returned is unspecified. A zero
result has the sign of X when S'Signed_Zeros is True. This
function provides access to the rounding behavior which is
most efficient on the target processor. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="137" name="Machine_Rounds" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the value True if rounding is performed on inexact
results of every predefined operation that yields a result of
the type T; yields the value False otherwise. The value of
this attribute is of the predefined type Boolean. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="139" name="Machine_Rounds" origin="Ada RM" category="variable">
<DOC>For every subtype S of a fixed point type T:
Yields the value True if rounding is performed on inexact
results of every predefined operation that yields a result of
the type T; yields the value False otherwise. The value of
this attribute is of the predefined type Boolean. See A.5.4.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Machine_Size" origin="GNAT RM" category="variable">
<DOC>This attribute is identical to the `Object_Size' attribute. It is
provided for compatibility with the DEC Ada 83 attribute of this name.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Mantissa" origin="GNAT RM" category="variable">
<DOC>The `Mantissa' attribute is provided for compatibility with Ada 83. See
the Ada 83 reference manual for an exact description of the semantics of
this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="141" name="Max" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Max denotes a function with the following specification:
function S'Max(Left, Right : S'Base)
return S'Base
The function returns the greater of the values of the two
parameters. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="144.1/3" name="Max_Alignment_For_Allocation" origin="Ada RM" category="unknown">
<DOC>For every subtype S:
Denotes the maximum value for Alignment that could be
requested by the implementation via Allocate for an access
type whose designated subtype is S. The value of this
attribute is of type universal_integer. See 13.11.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Max_Integer_Size" origin="GNAT RM" category="variable">
<DOC>`Standard'Max_Integer_Size' (`Standard' is the only permissible prefix)
provides the size of the largest supported integer type for the target.
The result is a static constant.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="145" name="Max_Size_In_Storage_Elements" origin="Ada RM" category="variable">
<DOC>For every subtype S:
Denotes the maximum value for Size_In_Storage_Elements that
could be requested by the implementation via Allocate for an
access type whose designated subtype is S. The value of this
attribute is of type universal_integer. See 13.11.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Maximum_Alignment" origin="GNAT RM" category="variable">
<DOC>`Standard'Maximum_Alignment' (`Standard' is the only permissible
prefix) provides the maximum useful alignment value for the target.
This is a static value that can be used to specify the alignment for an
object, guaranteeing that it is properly aligned in all cases.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Mechanism_Code" origin="GNAT RM" category="variable">
<DOC>`func'Mechanism_Code' yields an integer code for the mechanism used for
the result of function `func', and `subprog'Mechanism_Code (n)' yields
the mechanism used for formal parameter number `n' (a static integer
value, with 1 meaning the first parameter) of subprogram `subprog'.
The code returned is:
`1'
by copy (value)
`2'
by reference</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="147" name="Min" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Min denotes a function with the following specification:
function S'Min(Left, Right : S'Base)
return S'Base
The function returns the lesser of the values of the two
parameters. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="150.1/2" name="Mod" origin="Ada RM" category="function">
<DOC>For every modular subtype S:
S'Mod denotes a function with the following specification:
function S'Mod (Arg : universal_integer)
return S'Base
This function returns Arg mod S'Modulus, as a value of the
type of S. See 3.5.4.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="151" name="Model" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Model denotes a function with the following specification:
function S'Model (X : T)
return T
If the Numerics Annex is not supported, the meaning of this
attribute is implementation defined; see G.2.2 for the
definition that applies to implementations supporting the
Numerics Annex. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="155" name="Model_Emin" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
If the Numerics Annex is not supported, this attribute yields
an implementation defined value that is greater than or equal
to the value of T'Machine_Emin. See G.2.2 for further
requirements that apply to implementations supporting the
Numerics Annex. The value of this attribute is of the type
universal_integer. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="157" name="Model_Epsilon" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the value T'Machine_Radix(1 - T'Model_Mantissa). The
value of this attribute is of the type universal_real. See
A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="159" name="Model_Mantissa" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
If the Numerics Annex is not supported, this attribute yields
an implementation defined value that is greater than or equal
to Ceiling(d x log(10) / log(T'Machine_Radix)) + 1, where d is
the requested decimal precision of T, and less than or equal
to the value of T'Machine_Mantissa. See G.2.2 for further
requirements that apply to implementations supporting the
Numerics Annex. The value of this attribute is of the type
universal_integer. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="161" name="Model_Small" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the value T'Machine_Radix(T'Model_Emin - 1). The value
of this attribute is of the type universal_real. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="163" name="Modulus" origin="Ada RM" category="variable">
<DOC>For every modular subtype S:
S'Modulus yields the modulus of the type of S, as a value of
the type universal_integer. See 3.5.4.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Null_Parameter" origin="GNAT RM" category="variable">
<DOC>A reference `T'Null_Parameter' denotes an imaginary object of type or
subtype `T' allocated at machine address zero. The attribute is
allowed only as the default expression of a formal parameter, or as an
actual expression of a subprogram call. In either case, the subprogram
must be imported.
The identity of the object is represented by the address zero in the
argument list, independent of the passing mechanism (explicit or
default).
This capability is needed to specify that a zero address should be
passed for a record or other composite object passed by reference.
There is no way of indicating this without the `Null_Parameter'
attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Object_Size" origin="GNAT RM" category="variable">
<DOC>The size of an object is not necessarily the same as the size of the
type of an object. This is because by default object sizes are
increased to be a multiple of the alignment of the object. For example,
`Natural'Size' is 31, but by default objects of type `Natural' will
have a size of 32 bits. Similarly, a record containing an integer and
a character:
type Rec is record
I : Integer;
C : Character;
end record;
will have a size of 40 (that is `Rec'Size' will be 40). The alignment
will be 4, because of the integer field, and so the default size of
record objects for this type will be 64 (8 bytes).
If the alignment of the above record is specified to be 1, then the
object size will be 40 (5 bytes). This is true by default, and also an
object size of 40 can be explicitly specified in this case.
A consequence of this capability is that different object sizes can be
given to subtypes that would otherwise be considered in Ada to be
statically matching. But it makes no sense to consider such subtypes
as statically matching. Consequently, GNAT adds a rule to the static
matching rules that requires object sizes to match. Consider this
example:
procedure BadAVConvert is
type R is new Integer;
subtype R1 is R range 1 .. 10;
subtype R2 is R range 1 .. 10;
for R1'Object_Size use 8;
for R2'Object_Size use 16;
type R1P is access all R1;
type R2P is access all R2;
R1PV : R1P := new R1'(4);
R2PV : R2P;
begin
R2PV := R2P (R1PV);
|
&gt;&gt;&gt; target designated subtype not compatible with
type "R1" defined at line 3
end;
In the absence of lines 5 and 6, types `R1' and `R2' statically match
and hence the conversion on line 12 is legal. But since lines 5 and 6
cause the object sizes to differ, GNAT considers that types `R1' and
`R2' are not statically matching, and line 12 generates the diagnostic
shown above.
Similar additional checks are performed in other contexts requiring
statically matching subtypes.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Old" origin="GNAT RM" category="unknown">
<DOC>In addition to the usage of `Old' defined in the Ada 2012 RM (usage
within `Post' aspect), GNAT also permits the use of this attribute in
implementation defined pragmas `Postcondition', `Contract_Cases' and
`Test_Case'. Also usages of `Old' which would be illegal according to
the Ada 2012 RM definition are allowed under control of implementation
defined pragma `Unevaluated_Use_Of_Old'.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="164.1/3" name="Old" origin="Ada RM" category="unknown">
<DOC>For a prefix X that denotes an object of a nonlimited type:
Each X'Old in a postcondition expression that is enabled
denotes a constant that is implicitly declared at the
beginning of the subprogram body, entry body, or accept
statement. See 6.1.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="169" name="Output" origin="Ada RM" category="procedure">
<DOC>For every subtype S of a specific type T:
S'Output denotes a procedure with the following specification:
procedure S'Output(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T)
S'Output writes the value of Item to Stream, including any
bounds or discriminants. See 13.13.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="172.1/3" name="Overlaps_Storage" origin="Ada RM" category="unknown">
<DOC>For a prefix X that denotes an object:
X'Overlaps_Storage denotes a function with the following
specification:
function X'Overlaps_Storage (Arg : any_type)
return Boolean
The actual parameter shall be a name that denotes an object.
The object denoted by the actual parameter can be of any type.
This function evaluates the names of the objects involved and
returns True if the representation of the object denoted by
the actual parameter shares at least one bit with the
representation of the object denoted by X; otherwise, it
returns False. See 13.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="173/1" name="Partition_Id" origin="Ada RM" category="variable">
<DOC>For a prefix D that denotes a library-level declaration,
excepting a declaration of or within a declared-pure library
unit:
Denotes a value of the type universal_integer that identifies
the partition in which D was elaborated. If D denotes the
declaration of a remote call interface library unit (see
E.2.3) the given partition is the one where the body of D was
elaborated. See E.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Passed_By_Reference" origin="GNAT RM" category="variable">
<DOC>`typ'Passed_By_Reference' for any subtype `typ' returns a value of type
`Boolean' value that is `True' if the type is normally passed by
reference and `False' if the type is normally passed by copy in calls.
For scalar types, the result is always `False' and is static. For
non-scalar types, the result is nonstatic.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Pool_Address" origin="GNAT RM" category="variable">
<DOC>`X'Pool_Address' for any object `X' returns the address of X within its
storage pool. This is the same as `X'Address', except that for an
unconstrained array whose bounds are allocated just before the first
component, `X'Pool_Address' returns the address of those bounds,
whereas `X'Address' returns the address of the first component.
Here, we are interpreting 'storage pool' broadly to mean `wherever the
object is allocated', which could be a user-defined storage pool, the
global heap, on the stack, or in a static memory area. For an object
created by `new', `Ptr.all'Pool_Address' is what is passed to
`Allocate' and returned from `Deallocate'.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="175" name="Pos" origin="Ada RM" category="function">
<DOC>For every discrete subtype S:
S'Pos denotes a function with the following specification:
function S'Pos(Arg : S'Base)
return universal_integer
This function returns the position number of the value of Arg,
as a value of type universal_integer. See 3.5.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="179" name="Position" origin="Ada RM" category="variable">
<DOC>For a component C of a composite, non-array object R:
If the nondefault bit ordering applies to the composite type,
and if a component_clause specifies the placement of C,
denotes the value given for the position of the
component_clause; otherwise, denotes the same value as
R.C'Address - R'Address. The value of this attribute is of the
type universal_integer. See 13.5.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="181" name="Pred" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Pred denotes a function with the following specification:
function S'Pred(Arg : S'Base)
return S'Base
For an enumeration type, the function returns the value whose
position number is one less than that of the value of Arg;
Constraint_Error is raised if there is no such value of the
type. For an integer type, the function returns the result of
subtracting one from the value of Arg. For a fixed point type,
the function returns the result of subtracting small from the
value of Arg. For a floating point type, the function returns
the machine number (as defined in 3.5.7) immediately below the
value of Arg; Constraint_Error is raised if there is no such
machine number. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="184.1/2" name="Priority" origin="Ada RM" category="variable">
<DOC>For a prefix P that denotes a protected object:
Denotes a non-aliased component of the protected object P.
This component is of type System.Any_Priority and its value is
the priority of P. P'Priority denotes a variable if and only
if P denotes a variable. A reference to this attribute shall
appear only within the body of P. See D.5.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="185/1" name="Range" origin="Ada RM" category="type">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'Range is equivalent to the range A'First .. A'Last, except
that the prefix A is only evaluated once. See 3.6.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="187" name="Range" origin="Ada RM" category="type">
<DOC>For every scalar subtype S:
S'Range is equivalent to the range S'First .. S'Last. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="189/1" name="Range(N)" origin="Ada RM" category="type">
<DOC>For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
A'Range(N) is equivalent to the range A'First(N) .. A'Last(N),
except that the prefix A is only evaluated once. See 3.6.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Range_Length" origin="GNAT RM" category="variable">
<DOC>`typ'Range_Length' for any discrete type `typ' yields the number of
values represented by the subtype (zero for a null range). The result
is static for static subtypes. `Range_Length' applied to the index
subtype of a one dimensional array always gives the same result as
`Length' applied to the array itself.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="195" name="Read" origin="Ada RM" category="procedure">
<DOC>For every subtype S of a specific type T:
S'Read denotes a procedure with the following specification:
procedure S'Read(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : out T)
S'Read reads the value of Item from Stream. See 13.13.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="199" name="Remainder" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Remainder denotes a function with the following
specification:
function S'Remainder (X, Y : T)
return T
For nonzero Y, let v be the value X - n x Y, where n is the
integer nearest to the exact value of X/Y; if |n - X/Y| = 1/2,
then n is chosen to be even. If v is a machine number of the
type T, the function yields v; otherwise, it yields zero.
Constraint_Error is raised if Y is zero. A zero result has the
sign of X when S'Signed_Zeros is True. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Restriction_Set" origin="GNAT RM" category="unknown">
<DOC>This attribute allows compile time testing of restrictions that are
currently in effect. It is primarily intended for specializing code in
the run-time based on restrictions that are active (e.g. don't need to
save fpt registers if restriction No_Floating_Point is known to be in
effect), but can be used anywhere.
There are two forms:
System'Restriction_Set (partition_boolean_restriction_NAME)
System'Restriction_Set (No_Dependence =&gt; library_unit_NAME);
In the case of the first form, the only restriction names allowed are
parameterless restrictions that are checked for consistency at bind
time. For a complete list see the subtype
`System.Rident.Partition_Boolean_Restrictions'.
The result returned is True if the restriction is known to be in
effect, and False if the restriction is known not to be in effect. An
important guarantee is that the value of a Restriction_Set attribute is
known to be consistent throughout all the code of a partition.
This is trivially achieved if the entire partition is compiled with a
consistent set of restriction pragmas. However, the compilation model
does not require this. It is possible to compile one set of units with
one set of pragmas, and another set of units with another set of
pragmas. It is even possible to compile a spec with one set of pragmas,
and then WITH the same spec with a different set of pragmas.
Inconsistencies in the actual use of the restriction are checked at
bind time.
In order to achieve the guarantee of consistency for the
Restriction_Set pragma, we consider that a use of the pragma that
yields False is equivalent to a violation of the restriction.
So for example if you write
if System'Restriction_Set (No_Floating_Point) then
else
end if;
And the result is False, so that the else branch is executed, you can
assume that this restriction is not set for any unit in the partition.
This is checked by considering this use of the restriction pragma to be
a violation of the restriction No_Floating_Point. This means that no
other unit can attempt to set this restriction (if some unit does
attempt to set it, the binder will refuse to bind the partition).
Technical note: The restriction name and the unit name are intepreted
entirely syntactically, as in the corresponding Restrictions pragma,
they are not analyzed semantically, so they do not have a type.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Result" origin="GNAT RM" category="unknown">
<DOC>`function'Result' can only be used with in a Postcondition pragma for a
function. The prefix must be the name of the corresponding function.
This is used to refer to the result of the function in the
postcondition expression. For a further discussion of the use of this
attribute and examples of its use, see the description of pragma
Postcondition.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="202.1/3" name="Result" origin="Ada RM" category="unknown">
<DOC>For a prefix F that denotes a function declaration:
Within a postcondition expression for function F, denotes the
result object of the function. The type of this attribute is
that of the function result except within a Post'Class
postcondition expression for a function with a controlling
result or with a controlling access result. For a controlling
result, the type of the attribute is T'Class, where T is the
function result type. For a controlling access result, the
type of the attribute is an anonymous access type whose
designated type is T'Class, where T is the designated type of
the function result type. See 6.1.1.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="203" name="Round" origin="Ada RM" category="function">
<DOC>For every decimal fixed point subtype S:
S'Round denotes a function with the following specification:
function S'Round(X : universal_real)
return S'Base
The function returns the value obtained by rounding X (away
from 0, if X is midway between two values of the type of S).
See 3.5.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="207" name="Rounding" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Rounding denotes a function with the following
specification:
function S'Rounding (X : T)
return T
The function yields the integral value nearest to X, rounding
away from zero if X lies exactly halfway between two integers.
A zero result has the sign of X when S'Signed_Zeros is True.
See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Safe_Emax" origin="GNAT RM" category="variable">
<DOC>The `Safe_Emax' attribute is provided for compatibility with Ada 83.
See the Ada 83 reference manual for an exact description of the
semantics of this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="211" name="Safe_First" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the lower bound of the safe range (see 3.5.7) of the
type T. If the Numerics Annex is not supported, the value of
this attribute is implementation defined; see G.2.2 for the
definition that applies to implementations supporting the
Numerics Annex. The value of this attribute is of the type
universal_real. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Safe_Large" origin="GNAT RM" category="variable">
<DOC>The `Safe_Large' attribute is provided for compatibility with Ada 83.
See the Ada 83 reference manual for an exact description of the
semantics of this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="213" name="Safe_Last" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the upper bound of the safe range (see 3.5.7) of the
type T. If the Numerics Annex is not supported, the value of
this attribute is implementation defined; see G.2.2 for the
definition that applies to implementations supporting the
Numerics Annex. The value of this attribute is of the type
universal_real. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Safe_Small" origin="GNAT RM" category="unknown">
<DOC>The `Safe_Small' attribute is provided for compatibility with Ada 83.
See the Ada 83 reference manual for an exact description of the
semantics of this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Scalar_Storage_Order" origin="GNAT RM" category="unknown">
<DOC>For every array or record type `S', the representation attribute
`Scalar_Storage_Order' denotes the order in which storage elements that
make up scalar components are ordered within S. The value given must be
a static expression of type System.Bit_Order. The following is an
example of the use of this feature:
-- Component type definitions
subtype Yr_Type is Natural range 0 .. 127;
subtype Mo_Type is Natural range 1 .. 12;
subtype Da_Type is Natural range 1 .. 31;
-- Record declaration
type Date is record
Years_Since_1980 : Yr_Type;
Month : Mo_Type;
Day_Of_Month : Da_Type;
end record;
-- Record representation clause
for Date use record
Years_Since_1980 at 0 range 0 .. 6;
Month at 0 range 7 .. 10;
Day_Of_Month at 0 range 11 .. 15;
end record;
-- Attribute definition clauses
for Date'Bit_Order use System.High_Order_First;
for Date'Scalar_Storage_Order use System.High_Order_First;
-- If Scalar_Storage_Order is specified, it must be consistent with
-- Bit_Order, so it's best to always define the latter explicitly if
-- the former is used.
Other properties are as for the standard representation attribute
`Bit_Order' defined by Ada RM 13.5.3(4). The default is
`System.Default_Bit_Order'.
For a record type `T', if `T'Scalar_Storage_Order' is specified
explicitly, it shall be equal to `T'Bit_Order'. Note: this means that
if a `Scalar_Storage_Order' attribute definition clause is not
confirming, then the type's `Bit_Order' shall be specified explicitly
and set to the same value.
Derived types inherit an explicitly set scalar storage order from their
parent types. This may be overridden for the derived type by giving an
explicit scalar storage order for it. However, for a record extension,
the derived type must have the same scalar storage order as the parent
type.
A component of a record type that is itself a record or an array and
that does not start and end on a byte boundary must have have the same
scalar storage order as the record type. A component of a bit-packed
array type that is itself a record or an array must have the same
scalar storage order as the array type.
No component of a type that has an explicit `Scalar_Storage_Order'
attribute definition may be aliased.
A confirming `Scalar_Storage_Order' attribute definition clause (i.e.
with a value equal to `System.Default_Bit_Order') has no effect.
If the opposite storage order is specified, then whenever the value of
a scalar component of an object of type `S' is read, the storage
elements of the enclosing machine scalar are first reversed (before
retrieving the component value, possibly applying some shift and mask
operatings on the enclosing machine scalar), and the opposite operation
is done for writes.
In that case, the restrictions set forth in 13.5.1(10.3/2) for scalar
components are relaxed. Instead, the following rules apply:
* the underlying storage elements are those at positions `(position
+ first_bit / storage_element_size) .. (position + (last_bit +
storage_element_size - 1) / storage_element_size)'
* the sequence of underlying storage elements shall have a size no
greater than the largest machine scalar
* the enclosing machine scalar is defined as the smallest machine
scalar starting at a position no greater than `position +
first_bit / storage_element_size' and covering storage elements at
least up to `position + (last_bit + storage_element_size - 1) /
storage_element_size`'
* the position of the component is interpreted relative to that
machine scalar.
If no scalar storage order is specified for a type (either directly, or
by inheritance in the case of a derived type), then the default is
normally the native ordering of the target, but this default can be
overridden using pragma `Default_Scalar_Storage_Order'.
If a component of `T' is itself of a record or array type, the specfied
`Scalar_Storage_Order' does `not' apply to that nested type: an explicit
attribute definition clause must be provided for the component type as
well if desired.
Note that the scalar storage order only affects the in-memory data
representation. It has no effect on the representation used by stream
attributes.
Note that debuggers may be unable to display the correct value of scalar
components of a type for which the opposite storage order is specified.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="215" name="Scale" origin="Ada RM" category="variable">
<DOC>For every decimal fixed point subtype S:
S'Scale denotes the scale of the subtype S, defined as the
value N such that S'Delta = 10.0**(-N). The scale indicates
the position of the point relative to the rightmost
significant digits of values of subtype S. The value of this
attribute is of the type universal_integer. See 3.5.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="217" name="Scaling" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Scaling denotes a function with the following specification:
function S'Scaling (X : T;
Adjustment : universal_integer)
return T
Let v be the value X x T'Machine_Radix(Adjustment). If v is a
machine number of the type T, or if |v| &gt;= T'Model_Small, the
function yields v; otherwise, it yields either one of the
machine numbers of the type T adjacent to v. Constraint_Error
is optionally raised if v is outside the base range of S. A
zero result has the sign of X when S'Signed_Zeros is True. See
A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="221" name="Signed_Zeros" origin="Ada RM" category="variable">
<DOC>For every subtype S of a floating point type T:
Yields the value True if the hardware representation for the
type T has the capability of representing both positively and
negatively signed zeros, these being generated and used by the
predefined operations of the type T as specified in IEC
:1989; yields the value False otherwise. The value of this
attribute is of the predefined type Boolean. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Simple_Storage_Pool" origin="GNAT RM" category="unknown">
<DOC>For every nonformal, nonderived access-to-object type `Acc', the
representation attribute `Simple_Storage_Pool' may be specified via an
attribute_definition_clause (or by specifying the equivalent aspect):
My_Pool : My_Simple_Storage_Pool_Type;
type Acc is access My_Data_Type;
for Acc'Simple_Storage_Pool use My_Pool;
The name given in an attribute_definition_clause for the
`Simple_Storage_Pool' attribute shall denote a variable of a 'simple
storage pool type' (see pragma `Simple_Storage_Pool_Type').
The use of this attribute is only allowed for a prefix denoting a type
for which it has been specified. The type of the attribute is the type
of the variable specified as the simple storage pool of the access type,
and the attribute denotes that variable.
It is illegal to specify both `Storage_Pool' and `Simple_Storage_Pool'
for the same access type.
If the `Simple_Storage_Pool' attribute has been specified for an access
type, then applying the `Storage_Pool' attribute to the type is flagged
with a warning and its evaluation raises the exception `Program_Error'.
If the Simple_Storage_Pool attribute has been specified for an access
type `S', then the evaluation of the attribute `S'Storage_Size' returns
the result of calling `Storage_Size (S'Simple_Storage_Pool)', which is
intended to indicate the number of storage elements reserved for the
simple storage pool. If the Storage_Size function has not been defined
for the simple storage pool type, then this attribute returns zero.
If an access type `S' has a specified simple storage pool of type
`SSP', then the evaluation of an allocator for that access type calls
the primitive `Allocate' procedure for type `SSP', passing
`S'Simple_Storage_Pool' as the pool parameter. The detailed semantics
of such allocators is the same as those defined for allocators in
section 13.11 of the `Ada Reference Manual', with the term `simple
storage pool' substituted for `storage pool'.
If an access type `S' has a specified simple storage pool of type
`SSP', then a call to an instance of the `Ada.Unchecked_Deallocation'
for that access type invokes the primitive `Deallocate' procedure for
type `SSP', passing `S'Simple_Storage_Pool' as the pool parameter. The
detailed semantics of such unchecked deallocations is the same as
defined in section 13.11.2 of the Ada Reference Manual, except that the
term `simple storage pool' is substituted for `storage pool'.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="223" name="Size" origin="Ada RM" category="variable">
<DOC>For every subtype S:
If S is definite, denotes the size (in bits) that the
implementation would choose for the following objects of
subtype S:
* A record component of subtype S when the record type is
packed.
* The formal parameter of an instance of
Unchecked_Conversion that converts from subtype S to some
other subtype.
If S is indefinite, the meaning is implementation defined. The
value of this attribute is of the type universal_integer. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="228/1" name="Size" origin="Ada RM" category="variable">
<DOC>For a prefix X that denotes an object:
Denotes the size in bits of the representation of the object.
The value of this attribute is of the type universal_integer.
See 13.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Small" origin="GNAT RM" category="variable">
<DOC>The `Small' attribute is defined in Ada 95 (and Ada 2005) only for
fixed-point types. GNAT also allows this attribute to be applied to
floating-point types for compatibility with Ada 83. See the Ada 83
reference manual for an exact description of the semantics of this
attribute when applied to floating-point types.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="230" name="Small" origin="Ada RM" category="variable">
<DOC>For every fixed point subtype S:
S'Small denotes the small of the type of S. The value of this
attribute is of the type universal_real. See 3.5.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="232" name="Storage_Pool" origin="Ada RM" category="variable">
<DOC>For every access-to-object subtype S:
Denotes the storage pool of the type of S. The type of this
attribute is Root_Storage_Pool'Class. See 13.11.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="234" name="Storage_Size" origin="Ada RM" category="variable">
<DOC>For every access-to-object subtype S:
Yields the result of calling Storage_Size(S'Storage_Pool),
which is intended to be a measure of the number of storage
elements reserved for the pool. The type of this attribute is
universal_integer. See 13.11.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="236/1" name="Storage_Size" origin="Ada RM" category="variable">
<DOC>For a prefix T that denotes a task object (after any implicit
dereference):
Denotes the number of storage elements reserved for the task.
The value of this attribute is of the type universal_integer.
The Storage_Size includes the size of the task's stack, if
any. The language does not specify whether or not it includes
other storage associated with the task (such as the "task
control block" used by some implementations.) See 13.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Storage_Unit" origin="GNAT RM" category="variable">
<DOC>`Standard'Storage_Unit' (`Standard' is the only permissible prefix)
provides the same value as `System.Storage_Unit'.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="237.1/2" name="Stream_Size" origin="Ada RM" category="unknown">
<DOC>For every subtype S of an elementary type T:
Denotes the number of bits read from or written to a stream by
the default implementations of S'Read and S'Write. Hence, the
number of stream elements required per item of elementary type
T is:
T'Stream_Size / Ada.Streams.Stream_Element'Size
The value of this attribute is of type universal_integer and
is a multiple of Stream_Element'Size. See 13.13.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Stub_Type" origin="GNAT RM" category="type">
<DOC>The GNAT implementation of remote access-to-classwide types is
organized as described in AARM section E.4 (20.t): a value of an RACW
type (designating a remote object) is represented as a normal access
value, pointing to a "stub" object which in turn contains the necessary
information to contact the designated remote object. A call on any
dispatching operation of such a stub object does the remote call, if
necessary, using the information in the stub object to locate the
target partition, etc.
For a prefix `T' that denotes a remote access-to-classwide type,
`T'Stub_Type' denotes the type of the corresponding stub objects.
By construction, the layout of `T'Stub_Type' is identical to that of
type `RACW_Stub_Type' declared in the internal implementation-defined
unit `System.Partition_Interface'. Use of this attribute will create an
implicit dependency on this unit.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="238" name="Succ" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Succ denotes a function with the following specification:
function S'Succ(Arg : S'Base)
return S'Base
For an enumeration type, the function returns the value whose
position number is one more than that of the value of Arg;
Constraint_Error is raised if there is no such value of the
type. For an integer type, the function returns the result of
adding one to the value of Arg. For a fixed point type, the
function returns the result of adding small to the value of
Arg. For a floating point type, the function returns the
machine number (as defined in 3.5.7) immediately above the
value of Arg; Constraint_Error is raised if there is no such
machine number. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="System_Allocator_Alignment" origin="GNAT RM" category="unknown">
<DOC>`Standard'System_Allocator_Alignment' (`Standard' is the only
permissible prefix) provides the observable guaranted to be honored by
the system allocator (malloc). This is a static value that can be used
in user storage pools based on malloc either to reject allocation with
alignment too large or to enable a realignment circuitry if the
alignment request is larger than this value.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="242" name="Tag" origin="Ada RM" category="variable">
<DOC>For every subtype S of a tagged type T (specific or
class-wide):
S'Tag denotes the tag of the type T (or if T is class-wide,
the tag of the root type of the corresponding class). The
value of this attribute is of type Tag. See 3.9.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="244" name="Tag" origin="Ada RM" category="variable">
<DOC>For a prefix X that is of a class-wide tagged type (after any
implicit dereference):
X'Tag denotes the tag of X. The value of this attribute is of
type Tag. See 3.9.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Target_Name" origin="GNAT RM" category="variable">
<DOC>`Standard'Target_Name' (`Standard' is the only permissible prefix)
provides a static string value that identifies the target for the
current compilation. For GCC implementations, this is the standard gcc
target name without the terminating slash (for example, GNAT 5.0 on
windows yields "i586-pc-mingw32msv").</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="246" name="Terminated" origin="Ada RM" category="variable">
<DOC>For a prefix T that is of a task type (after any implicit
dereference):
Yields the value True if the task denoted by T is terminated,
and False otherwise. The value of this attribute is of the
predefined type Boolean. See 9.9.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="To_Address" origin="GNAT RM" category="variable">
<DOC>The `System'To_Address' (`System' is the only permissible prefix)
denotes a function identical to `System.Storage_Elements.To_Address'
except that it is a static attribute. This means that if its argument
is a static expression, then the result of the attribute is a static
expression. This means that such an expression can be used in contexts
(e.g., preelaborable packages) which require a static expression and
where the function call could not be used (since the function call is
always nonstatic, even if its argument is static). The argument must be
in the range -(2**(m-1)) .. 2**m-1, where m is the memory size
(typically 32 or 64). Negative values are intepreted in a modular
manner (e.g., -1 means the same as 16#FFFF_FFFF# on a 32 bits machine).</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="To_Any" origin="GNAT RM" category="unknown">
<DOC>This internal attribute is used for the generation of remote subprogram
stubs in the context of the Distributed Systems Annex.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="248" name="Truncation" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Truncation denotes a function with the following
specification:
function S'Truncation (X : T)
return T
The function yields the value Ceiling(X) when X is negative,
and Floor(X) otherwise. A zero result has the sign of X when
S'Signed_Zeros is True. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="TypeCode" origin="GNAT RM" category="unknown">
<DOC>This internal attribute is used for the generation of remote subprogram
stubs in the context of the Distributed Systems Annex.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Type_Class" origin="GNAT RM" category="variable">
<DOC>`typ'Type_Class' for any type or subtype `typ' yields the value of the
type class for the full type of `typ'. If `typ' is a generic formal
type, the value is the value for the corresponding actual subtype. The
value of this attribute is of type `System.Aux_DEC.Type_Class', which
has the following definition:
type Type_Class is
(Type_Class_Enumeration,
Type_Class_Integer,
Type_Class_Fixed_Point,
Type_Class_Floating_Point,
Type_Class_Array,
Type_Class_Record,
Type_Class_Access,
Type_Class_Task,
Type_Class_Address);
Protected types yield the value `Type_Class_Task', which thus applies
to all concurrent types. This attribute is designed to be compatible
with the DEC Ada 83 attribute of the same name.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Type_Key" origin="GNAT RM" category="unknown">
<DOC>The `Type_Key' attribute is applicable to a type or subtype and yields
a value of type Standard.String containing encoded information about
the type or subtype. This provides improved compatibility with other
implementations that support this attribute.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="252" name="Unbiased_Rounding" origin="Ada RM" category="function">
<DOC>For every subtype S of a floating point type T:
S'Unbiased_Rounding denotes a function with the following
specification:
function S'Unbiased_Rounding (X : T)
return T
The function yields the integral value nearest to X, rounding
toward the even integer if X lies exactly halfway between two
integers. A zero result has the sign of X when S'Signed_Zeros
is True. See A.5.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="256" name="Unchecked_Access" origin="Ada RM" category="variable">
<DOC>For a prefix X that denotes an aliased view of an object:
All rules and semantics that apply to X'Access (see 3.10.2)
apply also to X'Unchecked_Access, except that, for the
purposes of accessibility rules and checks, it is as if X were
declared immediately within a library package. See 13.10.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Unconstrained_Array" origin="GNAT RM" category="variable">
<DOC>The `Unconstrained_Array' attribute can be used with a prefix that
denotes any type or subtype. It is a static attribute that yields
`True' if the prefix designates an unconstrained array, and `False'
otherwise. In a generic instance, the result is still static, and
yields the result of applying this test to the generic actual.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Universal_Literal_String" origin="GNAT RM" category="variable">
<DOC>The prefix of `Universal_Literal_String' must be a named number. The
static result is the string consisting of the characters of the number
as defined in the original source. This allows the user program to
access the actual text of named numbers without intermediate
conversions and without the need to enclose the strings in quotes (which
would preclude their use as numbers).
For example, the following program prints the first 50 digits of pi:
with Text_IO; use Text_IO;
with Ada.Numerics;
procedure Pi is
begin
Put (Ada.Numerics.Pi'Universal_Literal_String);
end;</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Unrestricted_Access" origin="GNAT RM" category="variable">
<DOC>The `Unrestricted_Access' attribute is similar to `Access' except that
all accessibility and aliased view checks are omitted. This is a
user-beware attribute.
For objects, it is similar to `Address', for which it is a desirable
replacement where the value desired is an access type. In other words,
its effect is similar to first applying the `Address' attribute and
then doing an unchecked conversion to a desired access type.
For subprograms, `P'Unrestricted_Access' may be used where `P'Access'
would be illegal, to construct a value of a less-nested named access
type that designates a more-nested subprogram. This value may be used
in indirect calls, so long as the more-nested subprogram still exists;
once the subprogram containing it has returned, such calls are
erroneous. For example:
package body P is
type Less_Nested is not null access procedure;
Global : Less_Nested;
procedure P1 is
begin
Global.all;
end P1;
procedure P2 is
Local_Var : Integer;
procedure More_Nested is
begin
Local_Var ...
end More_Nested;
begin
Global := More_Nested'Unrestricted_Access;
P1;
end P2;
end P;
When P1 is called from P2, the call via Global is OK, but if P1 were
called after P2 returns, it would be an erroneous use of a dangling
pointer.
For objects, it is possible to use `Unrestricted_Access' for any type.
However, if the result is of an access-to-unconstrained array subtype,
then the resulting pointer has the same scope as the context of the
attribute, and must not be returned to some enclosing scope. For
instance, if a function uses `Unrestricted_Access' to create an
access-to-unconstrained-array and returns that value to the caller, the
result will involve dangling pointers. In addition, it is only valid to
create pointers to unconstrained arrays using this attribute if the
pointer has the normal default 'fat' representation where a pointer has
two components, one points to the array and one points to the bounds.
If a size clause is used to force 'thin' representation for a pointer
to unconstrained where there is only space for a single pointer, then
the resulting pointer is not usable.
In the simple case where a direct use of Unrestricted_Access attempts
to make a thin pointer for a non-aliased object, the compiler will
reject the use as illegal, as shown in the following example:
with System; use System;
procedure SliceUA2 is
type A is access all String;
for A'Size use Standard'Address_Size;
procedure P (Arg : A) is
begin
null;
end P;
X : String := "hello world!";
X2 : aliased String := "hello world!";
AV : A := X'Unrestricted_Access; -- ERROR
|
&gt;&gt;&gt; illegal use of Unrestricted_Access attribute
&gt;&gt;&gt; attempt to generate thin pointer to unaliased object
begin
P (X'Unrestricted_Access); -- ERROR
|
&gt;&gt;&gt; illegal use of Unrestricted_Access attribute
&gt;&gt;&gt; attempt to generate thin pointer to unaliased object
P (X(7 .. 12)'Unrestricted_Access); -- ERROR
|
&gt;&gt;&gt; illegal use of Unrestricted_Access attribute
&gt;&gt;&gt; attempt to generate thin pointer to unaliased object
P (X2'Unrestricted_Access); -- OK
end;
but other cases cannot be detected by the compiler, and are considered
to be erroneous. Consider the following example:
with System; use System;
with System; use System;
procedure SliceUA is
type AF is access all String;
type A is access all String;
for A'Size use Standard'Address_Size;
procedure P (Arg : A) is
begin
if Arg'Length /= 6 then
raise Program_Error;
end if;
end P;
X : String := "hello world!";
Y : AF := X (7 .. 12)'Unrestricted_Access;
begin
P (A (Y));
end;
A normal unconstrained array value or a constrained array object marked
as aliased has the bounds in memory just before the array, so a thin
pointer can retrieve both the data and the bounds. But in this case,
the non-aliased object `X' does not have the bounds before the string.
If the size clause for type `A' were not present, then the pointer
would be a fat pointer, where one component is a pointer to the bounds,
and all would be well. But with the size clause present, the
conversion from fat pointer to thin pointer in the call loses the
bounds, and so this is erroneous, and the program likely raises a
`Program_Error' exception.
In general, it is advisable to completely avoid mixing the use of thin
pointers and the use of `Unrestricted_Access' where the designated type
is an unconstrained array. The use of thin pointers should be
restricted to cases of porting legacy code that implicitly assumes the
size of pointers, and such code should not in any case be using this
attribute.
Another erroneous situation arises if the attribute is applied to a
constant. The resulting pointer can be used to access the constant, but
the effect of trying to modify a constant in this manner is not
well-defined. Consider this example:
P : constant Integer := 4;
type R is access all Integer;
RV : R := P'Unrestricted_Access;
RV.all := 3;
Here we attempt to modify the constant P from 4 to 3, but the compiler
may or may not notice this attempt, and subsequent references to P may
yield either the value 3 or the value 4 or the assignment may blow up
if the compiler decides to put P in read-only memory. One particular
case where `Unrestricted_Access' can be used in this way is to modify
the value of an `in' parameter:
procedure K (S : in String) is
type R is access all Character;
RV : R := S (3)'Unrestricted_Access;
begin
RV.all := 'a';
end;
In general this is a risky approach. It may appear to "work" but such
uses of `Unrestricted_Access' are potentially non-portable, even from
one version of GNAT to another, so are best avoided if possible.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Update" origin="GNAT RM" category="unknown">
<DOC>The `Update' attribute creates a copy of an array or record value with
one or more modified components. The syntax is:
PREFIX'Update ( RECORD_COMPONENT_ASSOCIATION_LIST )
PREFIX'Update ( ARRAY_COMPONENT_ASSOCIATION {, ARRAY_COMPONENT_ASSOCIATION } )
PREFIX'Update ( MULTIDIMENSIONAL_ARRAY_COMPONENT_ASSOCIATION
{, MULTIDIMENSIONAL_ARRAY_COMPONENT_ASSOCIATION } )
MULTIDIMENSIONAL_ARRAY_COMPONENT_ASSOCIATION ::= INDEX_EXPRESSION_LIST_LIST =&gt; EXPRESSION
INDEX_EXPRESSION_LIST_LIST ::= INDEX_EXPRESSION_LIST {| INDEX_EXPRESSION_LIST }
INDEX_EXPRESSION_LIST ::= ( EXPRESSION {, EXPRESSION } )
where `PREFIX' is the name of an array or record object, the
association list in parentheses does not contain an `others' choice and
the box symbol `&lt;&gt;' may not appear in any expression. The effect is to
yield a copy of the array or record value which is unchanged apart from
the components mentioned in the association list, which are changed to
the indicated value. The original value of the array or record value is
not affected. For example:
type Arr is Array (1 .. 5) of Integer;
Avar1 : Arr := (1,2,3,4,5);
Avar2 : Arr := Avar1'Update (2 =&gt; 10, 3 .. 4 =&gt; 20);
yields a value for `Avar2' of 1,10,20,20,5 with `Avar1' begin
unmodified. Similarly:
type Rec is A, B, C : Integer;
Rvar1 : Rec := (A =&gt; 1, B =&gt; 2, C =&gt; 3);
Rvar2 : Rec := Rvar1'Update (B =&gt; 20);
yields a value for `Rvar2' of (A =&gt; 1, B =&gt; 20, C =&gt; 3), with `Rvar1'
being unmodifed. Note that the value of the attribute reference is
computed completely before it is used. This means that if you write:
Avar1 := Avar1'Update (1 =&gt; 10, 2 =&gt; Function_Call);
then the value of `Avar1' is not modified if `Function_Call' raises an
exception, unlike the effect of a series of direct assignments to
elements of `Avar1'. In general this requires that two extra complete
copies of the object are required, which should be kept in mind when
considering efficiency.
The `Update' attribute cannot be applied to prefixes of a limited type,
and cannot reference discriminants in the case of a record type. The
accessibility level of an Update attribute result object is defined as
for an aggregate.
In the record case, no component can be mentioned more than once. In
the array case, two overlapping ranges can appear in the association
list, in which case the modifications are processed left to right.
Multi-dimensional arrays can be modified, as shown by this example:
A : array (1 .. 10, 1 .. 10) of Integer;
A := A'Update ((1, 2) =&gt; 20, (3, 4) =&gt; 30);
which changes element (1,2) to 20 and (3,4) to 30.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="VADS_Size" origin="GNAT RM" category="variable">
<DOC>The `'VADS_Size' attribute is intended to make it easier to port legacy
code which relies on the semantics of `'Size' as implemented by the
VADS Ada 83 compiler. GNAT makes a best effort at duplicating the same
semantic interpretation. In particular, `'VADS_Size' applied to a
predefined or other primitive type with no Size clause yields the
Object_Size (for example, `Natural'Size' is 32 rather than 31 on
typical machines). In addition `'VADS_Size' applied to an object gives
the result that would be obtained by applying the attribute to the
corresponding type.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="258" name="Val" origin="Ada RM" category="function">
<DOC>For every discrete subtype S:
S'Val denotes a function with the following specification:
function S'Val(Arg : universal_integer)
return S'Base
This function returns a value of the type of S whose position
number equals the value of Arg. See 3.5.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="262" name="Valid" origin="Ada RM" category="variable">
<DOC>For a prefix X that denotes a scalar object (after any
implicit dereference):
Yields True if and only if the object denoted by X is normal,
has a valid representation, and then, if the preceding
conditions hold, the value of X also satisfies the predicates
of the nominal subtype of X. The value of this attribute is of
the predefined type Boolean. See 13.9.2.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Valid_Scalars" origin="GNAT RM" category="unknown">
<DOC>The `'Valid_Scalars' attribute is intended to make it easier to check
the validity of scalar subcomponents of composite objects. The
attribute is defined for any prefix `P' which denotes an object. Prefix
`P' can be any type except for tagged private or `Unchecked_Union'
types. The value of the attribute is of type `Boolean'.
`P'Valid_Scalars' yields `True' if and only if the evaluation of
`C'Valid' yields `True' for every scalar subcomponent `C' of `P', or if
`P' has no scalar subcomponents. Attribute `'Valid_Scalars' is
equivalent to attribute `'Valid' for scalar types.
It is not specified in what order the subcomponents are checked, nor
whether any more are checked after any one of them is determined to be
invalid. If the prefix `P' is of a class-wide type `T'Class' (where `T'
is the associated specific type), or if the prefix `P' is of a specific
tagged type `T', then only the subcomponents of `T' are checked; in
other words, components of extensions of `T' are not checked even if
`T'Class (P)'Tag /= T'Tag'.
The compiler will issue a warning if it can be determined at compile
time that the prefix of the attribute has no scalar subcomponents.
Note: `Valid_Scalars' can generate a lot of code, especially in the
case of a large variant record. If the attribute is called in many
places in the same program applied to objects of the same type, it can
reduce program size to write a function with a single use of the
attribute, and then call that function from multiple places.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="264" name="Value" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Value denotes a function with the following specification:
function S'Value(Arg : String)
return S'Base
This function returns a value given an image of the value as a
String, ignoring any leading or trailing spaces. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Value_Size" origin="GNAT RM" category="variable">
<DOC>`type'Value_Size' is the number of bits required to represent a value
of the given subtype. It is the same as `type'Size', but, unlike
`Size', may be set for non-first subtypes.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="268/1" name="Version" origin="Ada RM" category="variable">
<DOC>For a prefix P that statically denotes a program unit:
Yields a value of the predefined type String that identifies
the version of the compilation unit that contains the
declaration of the program unit. See E.3.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Wchar_T_Size" origin="GNAT RM" category="variable">
<DOC>`Standard'Wchar_T_Size' (`Standard' is the only permissible prefix)
provides the size in bits of the C `wchar_t' type primarily for
constructing the definition of this type in package `Interfaces.C'. The
result is a static constant.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="270" name="Wide_Image" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Wide_Image denotes a function with the following
specification:
function S'Wide_Image(Arg : S'Base)
return Wide_String
The function returns an image of the value of Arg as a
Wide_String. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="273.1/4" name="Wide_Image" origin="Ada RM" category="function">
<DOC>For a prefix X that denotes an object of a scalar type (after
any implicit dereference):
X'Wide_Image denotes the result of calling function
S'Wide_Image with Arg being X, where S is the nominal subtype
of X. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="274" name="Wide_Value" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Wide_Value denotes a function with the following
specification:
function S'Wide_Value(Arg : Wide_String)
return S'Base
This function returns a value given an image of the value as a
Wide_String, ignoring any leading or trailing spaces. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="277.1/2" name="Wide_Wide_Image" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Wide_Wide_Image denotes a function with the following
specification:
function S'Wide_Wide_Image(Arg : S'Base)
return Wide_Wide_String
The function returns an image of the value of Arg, that is, a
sequence of characters representing the value in display form.
See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="277.5/4" name="Wide_Wide_Image" origin="Ada RM" category="function">
<DOC>For a prefix X that denotes an object of a scalar type (after
any implicit dereference):
X'Wide_Wide_Image denotes the result of calling function
S'Wide_Wide_Image with Arg being X, where S is the nominal
subtype of X. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="277.7/2" name="Wide_Wide_Value" origin="Ada RM" category="function">
<DOC>For every scalar subtype S:
S'Wide_Wide_Value denotes a function with the following
specification:
function S'Wide_Wide_Value(Arg : Wide_Wide_String)
return S'Base
This function returns a value given an image of the value as a
Wide_Wide_String, ignoring any leading or trailing spaces. See</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="277.11/2" name="Wide_Wide_Width" origin="Ada RM" category="variable">
<DOC>For every scalar subtype S:
S'Wide_Wide_Width denotes the maximum length of a
Wide_Wide_String returned by S'Wide_Wide_Image over all values
of the subtype S. It denotes zero for a subtype that has a
null range. Its type is universal_integer. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="278" name="Wide_Width" origin="Ada RM" category="variable">
<DOC>For every scalar subtype S:
S'Wide_Width denotes the maximum length of a Wide_String
returned by S'Wide_Image over all values of the subtype S. It
denotes zero for a subtype that has a null range. Its type is
universal_integer. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="280" name="Width" origin="Ada RM" category="variable">
<DOC>For every scalar subtype S:
S'Width denotes the maximum length of a String returned by
S'Image over all values of the subtype S. It denotes zero for
a subtype that has a null range. Its type is
universal_integer. See 3.5.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="0" name="Word_Size" origin="GNAT RM" category="variable">
<DOC>`Standard'Word_Size' (`Standard' is the only permissible prefix)
provides the value `System.Word_Size'. The result is a static constant.</DOC>
</ATTRIBUTE>
<ATTRIBUTE id="286" name="Write" origin="Ada RM" category="procedure">
<DOC>For every subtype S of a specific type T:
S'Write denotes a procedure with the following specification:
procedure S'Write(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T)
S'Write writes the value of Item to Stream. See 13.13.2.</DOC>
</ATTRIBUTE>
<PRAGMA id="0" name="Abort_Defer" origin="GNAT RM">
<DOC>Syntax:
pragma Abort_Defer;
This pragma must appear at the start of the statement sequence of a
handled sequence of statements (right after the `begin'). It has the
effect of deferring aborts for the sequence of statements (but not for
the declarations or handlers, if any, associated with this statement
sequence).</DOC>
</PRAGMA>
<PRAGMA id="0" name="Abstract_State" origin="GNAT RM">
<DOC>Syntax:
pragma Abstract_State (ABSTRACT_STATE_LIST);
ABSTRACT_STATE_LIST ::=
null
| STATE_NAME_WITH_OPTIONS
| (STATE_NAME_WITH_OPTIONS {, STATE_NAME_WITH_OPTIONS} )
STATE_NAME_WITH_OPTIONS ::=
STATE_NAME
| (STATE_NAME with OPTION_LIST)
OPTION_LIST ::= OPTION {, OPTION}
OPTION ::=
SIMPLE_OPTION
| NAME_VALUE_OPTION
SIMPLE_OPTION ::= Ghost | Synchronous
NAME_VALUE_OPTION ::=
Part_Of =&gt; ABSTRACT_STATE
| External [=&gt; EXTERNAL_PROPERTY_LIST]
EXTERNAL_PROPERTY_LIST ::=
EXTERNAL_PROPERTY
| (EXTERNAL_PROPERTY {, EXTERNAL_PROPERTY} )
EXTERNAL_PROPERTY ::=
Async_Readers [=&gt; boolean_EXPRESSION]
| Async_Writers [=&gt; boolean_EXPRESSION]
| Effective_Reads [=&gt; boolean_EXPRESSION]
| Effective_Writes [=&gt; boolean_EXPRESSION]
others =&gt; boolean_EXPRESSION
STATE_NAME ::= defining_identifier
ABSTRACT_STATE ::= name
For the semantics of this pragma, see the entry for aspect
`Abstract_State' in the SPARK 2014 Reference Manual, section 7.1.4.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ada_05" origin="GNAT RM">
<DOC>Syntax:
pragma Ada_05;
pragma Ada_05 (local_NAME);
A configuration pragma that establishes Ada 2005 mode for the unit to
which it applies, regardless of the mode set by the command line
switches. This pragma is useful when writing a reusable component that
itself uses Ada 2005 features, but which is intended to be usable from
either Ada 83 or Ada 95 programs.
The one argument form (which is not a configuration pragma) is used for
managing the transition from Ada 95 to Ada 2005 in the run-time
library. If an entity is marked as Ada_2005 only, then referencing the
entity in Ada_83 or Ada_95 mode will generate a warning. In addition,
in Ada_83 or Ada_95 mode, a preference rule is established which does
not choose such an entity unless it is unambiguously specified. This
avoids extra subprograms marked this way from generating ambiguities in
otherwise legal pre-Ada_2005 programs. The one argument form is
intended for exclusive use in the GNAT run-time library.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ada_12" origin="GNAT RM">
<DOC>Syntax:
pragma Ada_12;
pragma Ada_12 (local_NAME);
A configuration pragma that establishes Ada 2012 mode for the unit to
which it applies, regardless of the mode set by the command line
switches. This mode is set automatically for the `Ada' and `System'
packages and their children, so you need not specify it in these
contexts. This pragma is useful when writing a reusable component that
itself uses Ada 2012 features, but which is intended to be usable from
Ada 83, Ada 95, or Ada 2005 programs.
The one argument form, which is not a configuration pragma, is used for
managing the transition from Ada 2005 to Ada 2012 in the run-time
library. If an entity is marked as Ada_2012 only, then referencing the
entity in any pre-Ada_2012 mode will generate a warning. In addition,
in any pre-Ada_2012 mode, a preference rule is established which does
not choose such an entity unless it is unambiguously specified. This
avoids extra subprograms marked this way from generating ambiguities in
otherwise legal pre-Ada_2012 programs. The one argument form is
intended for exclusive use in the GNAT run-time library.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ada_2005" origin="GNAT RM">
<DOC>Syntax:
pragma Ada_2005;
This configuration pragma is a synonym for pragma Ada_05 and has the
same syntax and effect.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ada_2012" origin="GNAT RM">
<DOC>Syntax:
pragma Ada_2012;
This configuration pragma is a synonym for pragma Ada_12 and has the
same syntax and effect.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ada_83" origin="GNAT RM">
<DOC>Syntax:
pragma Ada_83;
A configuration pragma that establishes Ada 83 mode for the unit to
which it applies, regardless of the mode set by the command line
switches. In Ada 83 mode, GNAT attempts to be as compatible with the
syntax and semantics of Ada 83, as defined in the original Ada 83
Reference Manual as possible. In particular, the keywords added by Ada
95 and Ada 2005 are not recognized, optional package bodies are allowed,
and generics may name types with unknown discriminants without using
the `(&lt;&gt;)' notation. In addition, some but not all of the additional
restrictions of Ada 83 are enforced.
Ada 83 mode is intended for two purposes. Firstly, it allows existing
Ada 83 code to be compiled and adapted to GNAT with less effort.
Secondly, it aids in keeping code backwards compatible with Ada 83.
However, there is no guarantee that code that is processed correctly by
GNAT in Ada 83 mode will in fact compile and execute with an Ada 83
compiler, since GNAT does not enforce all the additional checks
required by Ada 83.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ada_95" origin="GNAT RM">
<DOC>Syntax:
pragma Ada_95;
A configuration pragma that establishes Ada 95 mode for the unit to
which it applies, regardless of the mode set by the command line
switches. This mode is set automatically for the `Ada' and `System'
packages and their children, so you need not specify it in these
contexts. This pragma is useful when writing a reusable component that
itself uses Ada 95 features, but which is intended to be usable from
either Ada 83 or Ada 95 programs.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Aggregate_Individually_Assign" origin="GNAT RM">
<DOC>Syntax:
pragma Aggregate_Individually_Assign;
Where possible, GNAT will store the binary representation of a record
aggregate in memory for space and performance reasons. This
configuration pragma changes this behavior so that record aggregates
are instead always converted into individual assignment statements.</DOC>
</PRAGMA>
<PRAGMA id="0" name="All_Calls_Remote" origin="Ada RM">
<DOC>Syntax:
pragma All_Calls_Remote [(library_unit_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Allow_Integer_Address" origin="GNAT RM">
<DOC>Syntax:
pragma Allow_Integer_Address;
In almost all versions of GNAT, `System.Address' is a private type in
accordance with the implementation advice in the RM. This means that
integer values, in particular integer literals, are not allowed as
address values. If the configuration pragma `Allow_Integer_Address' is
given, then integer expressions may be used anywhere a value of type
`System.Address' is required. The effect is to introduce an implicit
unchecked conversion from the integer value to type `System.Address'.
The reverse case of using an address where an integer type is required
is handled analogously. The following example compiles without errors:
pragma Allow_Integer_Address;
with System; use System;
package AddrAsInt is
X : Integer;
Y : Integer;
for X'Address use 16#1240#;
for Y use at 16#3230#;
m : Address := 16#4000#;
n : constant Address := 4000;
p : constant Address := Address (X + Y);
v : Integer := y'Address;
w : constant Integer := Integer (Y'Address);
type R is new integer;
RR : R := 1000;
Z : Integer;
for Z'Address use RR;
end AddrAsInt;
Note that pragma `Allow_Integer_Address' is ignored if `System.Address'
is not a private type. In implementations of `GNAT' where
System.Address is a visible integer type, this pragma serves no purpose
but is ignored rather than rejected to allow common sets of sources to
be used in the two situations.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Annotate" origin="GNAT RM">
<DOC>Syntax:
pragma Annotate (IDENTIFIER [, IDENTIFIER {, ARG}] [, entity =&gt; local_NAME]);
ARG ::= NAME | EXPRESSION
This pragma is used to annotate programs. IDENTIFIER identifies the
type of annotation. GNAT verifies that it is an identifier, but does
not otherwise analyze it. The second optional identifier is also left
unanalyzed, and by convention is used to control the action of the tool
to which the annotation is addressed. The remaining ARG arguments can
be either string literals or more generally expressions. String
literals (and concatenations of string literals) are assumed to be
either of type `Standard.String' or else `Wide_String' or
`Wide_Wide_String' depending on the character literals they contain.
All other kinds of arguments are analyzed as expressions, and must be
unambiguous. The last argument if present must have the identifier
`Entity' and GNAT verifies that a local name is given.
The analyzed pragma is retained in the tree, but not otherwise processed
by any part of the GNAT compiler, except to generate corresponding note
lines in the generated ALI file. For the format of these note lines, see
the compiler source file lib-writ.ads. This pragma is intended for use
by external tools, including ASIS. The use of pragma Annotate does not
affect the compilation process in any way. This pragma may be used as a
configuration pragma.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Assert" origin="GNAT RM">
<DOC>Syntax:
pragma Assert (
boolean_EXPRESSION
[, string_EXPRESSION]);
The effect of this pragma depends on whether the corresponding command
line switch is set to activate assertions. The pragma expands into code
equivalent to the following:
if assertions-enabled then
if not boolean_EXPRESSION then
System.Assertions.Raise_Assert_Failure
(string_EXPRESSION);
end if;
end if;
The string argument, if given, is the message that will be associated
with the exception occurrence if the exception is raised. If no second
argument is given, the default message is `file':`nnn', where `file' is
the name of the source file containing the assert, and `nnn' is the
line number of the assert.
Note that, as with the `if' statement to which it is equivalent, the
type of the expression is either `Standard.Boolean', or any type derived
from this standard type.
Assert checks can be either checked or ignored. By default they are
ignored. They will be checked if either the command line switch
`-gnata' is used, or if an `Assertion_Policy' or `Check_Policy' pragma
is used to enable `Assert_Checks'.
If assertions are ignored, then there is no run-time effect (and in
particular, any side effects from the expression will not occur at run
time). (The expression is still analyzed at compile time, and may
cause types to be frozen if they are mentioned here for the first time).
If assertions are checked, then the given expression is tested, and if
it is `False' then `System.Assertions.Raise_Assert_Failure' is called
which results in the raising of `Assert_Failure' with the given message.
You should generally avoid side effects in the expression arguments of
this pragma, because these side effects will turn on and off with the
setting of the assertions mode, resulting in assertions that have an
effect on the program. However, the expressions are analyzed for
semantic correctness whether or not assertions are enabled, so turning
assertions on and off cannot affect the legality of a program.
Note that the implementation defined policy `DISABLE', given in a
pragma `Assertion_Policy', can be used to suppress this semantic
analysis.
Note: this is a standard language-defined pragma in versions of Ada
from 2005 on. In GNAT, it is implemented in all versions of Ada, and
the DISABLE policy is an implementation-defined addition.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Assert_And_Cut" origin="GNAT RM">
<DOC>Syntax:
pragma Assert_And_Cut (
boolean_EXPRESSION
[, string_EXPRESSION]);
The effect of this pragma is identical to that of pragma `Assert',
except that in an `Assertion_Policy' pragma, the identifier
`Assert_And_Cut' is used to control whether it is ignored or checked
(or disabled).
The intention is that this be used within a subprogram when the given
test expresion sums up all the work done so far in the subprogram, so
that the rest of the subprogram can be verified (informally or
formally) using only the entry preconditions, and the expression in
this pragma. This allows dividing up a subprogram into sections for the
purposes of testing or formal verification. The pragma also serves as
useful documentation.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Assertion_Policy" origin="GNAT RM">
<DOC>Syntax:
pragma Assertion_Policy (CHECK | DISABLE | IGNORE | SUPPRESSIBLE);
pragma Assertion_Policy (
ASSERTION_KIND =&gt; POLICY_IDENTIFIER
{, ASSERTION_KIND =&gt; POLICY_IDENTIFIER});
ASSERTION_KIND ::= RM_ASSERTION_KIND | ID_ASSERTION_KIND
RM_ASSERTION_KIND ::= Assert |
Static_Predicate |
Dynamic_Predicate |
Pre |
Pre'Class |
Post |
Post'Class |
Type_Invariant |
Type_Invariant'Class
ID_ASSERTION_KIND ::= Assertions |
Assert_And_Cut |
Assume |
Contract_Cases |
Debug |
Ghost |
Invariant |
Invariant'Class |
Loop_Invariant |
Loop_Variant |
Postcondition |
Precondition |
Predicate |
Refined_Post |
Statement_Assertions
POLICY_IDENTIFIER ::= Check | Disable | Ignore | Suppressible
This is a standard Ada 2012 pragma that is available as an
implementation-defined pragma in earlier versions of Ada. The
assertion kinds `RM_ASSERTION_KIND' are those defined in the Ada
standard. The assertion kinds `ID_ASSERTION_KIND' are implementation
defined additions recognized by the GNAT compiler.
The pragma applies in both cases to pragmas and aspects with matching
names, e.g. `Pre' applies to the Pre aspect, and `Precondition' applies
to both the `Precondition' pragma and the aspect `Precondition'. Note
that the identifiers for pragmas Pre_Class and Post_Class are Pre'Class
and Post'Class (not Pre_Class and Post_Class), since these pragmas are
intended to be identical to the corresponding aspects).
If the policy is `CHECK', then assertions are enabled, i.e. the
corresponding pragma or aspect is activated. If the policy is
`IGNORE', then assertions are ignored, i.e. the corresponding pragma
or aspect is deactivated. This pragma overrides the effect of the
`-gnata' switch on the command line. If the policy is `SUPPRESSIBLE',
then assertions are enabled by default, however, if the `-gnatp' switch
is specified all assertions are ignored.
The implementation defined policy `DISABLE' is like `IGNORE' except
that it completely disables semantic checking of the corresponding
pragma or aspect. This is useful when the pragma or aspect argument
references subprograms in a with'ed package which is replaced by a
dummy package for the final build.
The implementation defined assertion kind `Assertions' applies to all
assertion kinds. The form with no assertion kind given implies this
choice, so it applies to all assertion kinds (RM defined, and
implementation defined).
The implementation defined assertion kind `Statement_Assertions'
applies to `Assert', `Assert_And_Cut', `Assume', `Loop_Invariant', and
`Loop_Variant'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Assume" origin="GNAT RM">
<DOC>Syntax:
pragma Assume (
boolean_EXPRESSION
[, string_EXPRESSION]);
The effect of this pragma is identical to that of pragma `Assert',
except that in an `Assertion_Policy' pragma, the identifier `Assume' is
used to control whether it is ignored or checked (or disabled).
The intention is that this be used for assumptions about the external
environment. So you cannot expect to verify formally or informally that
the condition is met, this must be established by examining things
outside the program itself. For example, we may have code that depends
on the size of `Long_Long_Integer' being at least 64. So we could write:
pragma Assume (Long_Long_Integer'Size &gt;= 64);
This assumption cannot be proved from the program itself, but it acts
as a useful run-time check that the assumption is met, and documents
the need to ensure that it is met by reference to information outside
the program.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Assume_No_Invalid_Values" origin="GNAT RM">
<DOC>Syntax:
pragma Assume_No_Invalid_Values (On | Off);
This is a configuration pragma that controls the assumptions made by the
compiler about the occurrence of invalid representations (invalid
values) in the code.
The default behavior (corresponding to an Off argument for this
pragma), is to assume that values may in general be invalid unless the
compiler can prove they are valid. Consider the following example:
V1 : Integer range 1 .. 10;
V2 : Integer range 11 .. 20;
for J in V2 .. V1 loop
end loop;
if V1 and V2 have valid values, then the loop is known at compile time
not to execute since the lower bound must be greater than the upper
bound. However in default mode, no such assumption is made, and the
loop may execute. If `Assume_No_Invalid_Values (On)' is given, the
compiler will assume that any occurrence of a variable other than in an
explicit `'Valid' test always has a valid value, and the loop above
will be optimized away.
The use of `Assume_No_Invalid_Values (On)' is appropriate if you know
your code is free of uninitialized variables and other possible sources
of invalid representations, and may result in more efficient code. A
program that accesses an invalid representation with this pragma in
effect is erroneous, so no guarantees can be made about its behavior.
It is peculiar though permissible to use this pragma in conjunction
with validity checking (-gnatVa). In such cases, accessing invalid
values will generally give an exception, though formally the program is
erroneous so there are no guarantees that this will always be the case,
and it is recommended that these two options not be used together.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Async_Readers" origin="GNAT RM">
<DOC>Syntax:
pragma Async_Readers [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Async_Readers' in the SPARK 2014 Reference Manual, section 7.1.2.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Async_Writers" origin="GNAT RM">
<DOC>Syntax:
pragma Async_Writers [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Async_Writers' in the SPARK 2014 Reference Manual, section 7.1.2.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Asynchronous" origin="Ada RM">
<DOC>Syntax:
pragma Asynchronous;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Atomic" origin="Ada RM">
<DOC>Syntax:
pragma Atomic;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Atomic_Components" origin="Ada RM">
<DOC>Syntax:
pragma Atomic_Components;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Attach_Handler" origin="Ada RM">
<DOC>Syntax:
pragma Attach_Handler;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Attribute_Definition" origin="GNAT RM">
<DOC>Syntax:
pragma Attribute_Definition
([Attribute =&gt;] ATTRIBUTE_DESIGNATOR,
[Entity =&gt;] LOCAL_NAME,
[Expression =&gt;] EXPRESSION | NAME);
If `Attribute' is a known attribute name, this pragma is equivalent to
the attribute definition clause:
for Entity'Attribute use Expression;
If `Attribute' is not a recognized attribute name, the pragma is
ignored, and a warning is emitted. This allows source code to be
written that takes advantage of some new attribute, while remaining
compilable with earlier compilers.</DOC>
</PRAGMA>
<PRAGMA id="0" name="CPP_Class" origin="GNAT RM">
<DOC>Syntax:
pragma CPP_Class ([Entity =&gt;] LOCAL_NAME);
The argument denotes an entity in the current declarative region that is
declared as a record type. It indicates that the type corresponds to an
externally declared C++ class type, and is to be laid out the same way
that C++ would lay out the type. If the C++ class has virtual primitives
then the record must be declared as a tagged record type.
Types for which `CPP_Class' is specified do not have assignment or
equality operators defined (such operations can be imported or declared
as subprograms as required). Initialization is allowed only by
constructor functions (see pragma `CPP_Constructor'). Such types are
implicitly limited if not explicitly declared as limited or derived
from a limited type, and an error is issued in that case.
See *note Interfacing to C++: 47. for related information.
Note: Pragma `CPP_Class' is currently obsolete. It is supported for
backward compatibility but its functionality is available using pragma
`Import' with `Convention' = `CPP'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="CPP_Constructor" origin="GNAT RM">
<DOC>Syntax:
pragma CPP_Constructor ([Entity =&gt;] LOCAL_NAME
[, [External_Name =&gt;] static_string_EXPRESSION ]
[, [Link_Name =&gt;] static_string_EXPRESSION ]);
This pragma identifies an imported function (imported in the usual way
with pragma `Import') as corresponding to a C++ constructor. If
`External_Name' and `Link_Name' are not specified then the `Entity'
argument is a name that must have been previously mentioned in a pragma
`Import' with `Convention' = `CPP'. Such name must be of one of the
following forms:
* `function' `Fname' `return' T`
* `function' `Fname' `return' T'Class
* `function' `Fname' (...) `return' T`
* `function' `Fname' (...) `return' T'Class
where `T' is a limited record type imported from C++ with pragma
`Import' and `Convention' = `CPP'.
The first two forms import the default constructor, used when an object
of type `T' is created on the Ada side with no explicit constructor.
The latter two forms cover all the non-default constructors of the type.
See the GNAT User's Guide for details.
If no constructors are imported, it is impossible to create any objects
on the Ada side and the type is implicitly declared abstract.
Pragma `CPP_Constructor' is intended primarily for automatic generation
using an automatic binding generator tool (such as the `-fdump-ada-spec'
GCC switch). See *note Interfacing to C++: 47. for more related
information.
Note: The use of functions returning class-wide types for constructors
is currently obsolete. They are supported for backward compatibility.
The use of functions returning the type T leave the Ada sources more
clear because the imported C++ constructors always return an object of
type T; that is, they never return an object whose type is a descendant
of type T.</DOC>
</PRAGMA>
<PRAGMA id="0" name="CPP_Virtual" origin="GNAT RM">
<DOC>This pragma is now obsolete and, other than generating a warning if
warnings on obsolescent features are enabled, is completely ignored.
It is retained for compatibility purposes. It used to be required to
ensure compoatibility with C++, but is no longer required for that
purpose because GNAT generates the same object layout as the G++
compiler by default.
See *note Interfacing to C++: 47. for related information.</DOC>
</PRAGMA>
<PRAGMA id="0" name="CPP_Vtable" origin="GNAT RM">
<DOC>This pragma is now obsolete and, other than generating a warning if
warnings on obsolescent features are enabled, is completely ignored.
It used to be required to ensure compatibility with C++, but is no
longer required for that purpose because GNAT generates the same object
layout as the G++ compiler by default.
See *note Interfacing to C++: 47. for related information.</DOC>
</PRAGMA>
<PRAGMA id="0" name="CPU" origin="GNAT RM">
<DOC>Syntax:
pragma CPU (EXPRESSION);
This pragma is standard in Ada 2012, but is available in all earlier
versions of Ada as an implementation-defined pragma. See Ada 2012
Reference Manual for details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="C_Pass_By_Copy" origin="GNAT RM">
<DOC>Syntax:
pragma C_Pass_By_Copy
([Max_Size =&gt;] static_integer_EXPRESSION);
Normally the default mechanism for passing C convention records to C
convention subprograms is to pass them by reference, as suggested by RM
B.3(69). Use the configuration pragma `C_Pass_By_Copy' to change this
default, by requiring that record formal parameters be passed by copy
if all of the following conditions are met:
* The size of the record type does not exceed the value specified for
`Max_Size'.
* The record type has `Convention C'.
* The formal parameter has this record type, and the subprogram has a
foreign (non-Ada) convention.
If these conditions are met the argument is passed by copy; i.e., in a
manner consistent with what C expects if the corresponding formal in the
C prototype is a struct (rather than a pointer to a struct).
You can also pass records by copy by specifying the convention
`C_Pass_By_Copy' for the record type, or by using the extended `Import'
and `Export' pragmas, which allow specification of passing mechanisms
on a parameter by parameter basis.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Check" origin="GNAT RM">
<DOC>Syntax:
pragma Check (
[Name =&gt;] CHECK_KIND,
[Check =&gt;] Boolean_EXPRESSION
[, [Message =&gt;] string_EXPRESSION] );
CHECK_KIND ::= IDENTIFIER |
Pre'Class |
Post'Class |
Type_Invariant'Class |
Invariant'Class
This pragma is similar to the predefined pragma `Assert' except that an
extra identifier argument is present. In conjunction with pragma
`Check_Policy', this can be used to define groups of assertions that can
be independently controlled. The identifier `Assertion' is special, it
refers to the normal set of pragma `Assert' statements.
Checks introduced by this pragma are normally deactivated by default.
They can be activated either by the command line option `-gnata', which
turns on all checks, or individually controlled using pragma
`Check_Policy'.
The identifiers `Assertions' and `Statement_Assertions' are not
permitted as check kinds, since this would cause confusion with the use
of these identifiers in `Assertion_Policy' and `Check_Policy' pragmas,
where they are used to refer to sets of assertions.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Check_Float_Overflow" origin="GNAT RM">
<DOC>Syntax:
pragma Check_Float_Overflow;
In Ada, the predefined floating-point types (`Short_Float', `Float',
`Long_Float', `Long_Long_Float') are defined to be `unconstrained'.
This means that even though each has a well-defined base range, an
operation that delivers a result outside this base range is not
required to raise an exception. This implementation permission
accommodates the notion of infinities in IEEE floating-point, and
corresponds to the efficient execution mode on most machines. GNAT will
not raise overflow exceptions on these machines; instead it will
generate infinities and NaN's as defined in the IEEE standard.
Generating infinities, although efficient, is not always desirable.
Often the preferable approach is to check for overflow, even at the
(perhaps considerable) expense of run-time performance. This can be
accomplished by defining your own constrained floating-point subtypes -
i.e., by supplying explicit range constraints - and indeed such a
subtype can have the same base range as its base type. For example:
subtype My_Float is Float range Float'Range;
Here `My_Float' has the same range as `Float' but is constrained, so
operations on `My_Float' values will be checked for overflow against
this range.
This style will achieve the desired goal, but it is often more
convenient to be able to simply use the standard predefined
floating-point types as long as overflow checking could be guaranteed.
The `Check_Float_Overflow' configuration pragma achieves this effect.
If a unit is compiled subject to this configuration pragma, then all
operations on predefined floating-point types including operations on
base types of these floating-point types will be treated as though
those types were constrained, and overflow checks will be generated.
The `Constraint_Error' exception is raised if the result is out of
range.
This mode can also be set by use of the compiler switch `-gnateF'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Check_Name" origin="GNAT RM">
<DOC>Syntax:
pragma Check_Name (check_name_IDENTIFIER);
This is a configuration pragma that defines a new implementation
defined check name (unless IDENTIFIER matches one of the predefined
check names, in which case the pragma has no effect). Check names are
global to a partition, so if two or more configuration pragmas are
present in a partition mentioning the same name, only one new check
name is introduced.
An implementation defined check name introduced with this pragma may be
used in only three contexts: `pragma Suppress', `pragma Unsuppress',
and as the prefix of a `Check_Name'Enabled' attribute reference. For
any of these three cases, the check name must be visible. A check name
is visible if it is in the configuration pragmas applying to the
current unit, or if it appears at the start of any unit that is part of
the dependency set of the current unit (e.g., units that are mentioned
in `with' clauses).
Check names introduced by this pragma are subject to control by compiler
switches (in particular -gnatp) in the usual manner.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Check_Policy" origin="GNAT RM">
<DOC>Syntax:
pragma Check_Policy
([Name =&gt;] CHECK_KIND,
[Policy =&gt;] POLICY_IDENTIFIER);
pragma Check_Policy (
CHECK_KIND =&gt; POLICY_IDENTIFIER
{, CHECK_KIND =&gt; POLICY_IDENTIFIER});
ASSERTION_KIND ::= RM_ASSERTION_KIND | ID_ASSERTION_KIND
CHECK_KIND ::= IDENTIFIER |
Pre'Class |
Post'Class |
Type_Invariant'Class |
Invariant'Class
The identifiers Name and Policy are not allowed as CHECK_KIND values. This
avoids confusion between the two possible syntax forms for this pragma.
POLICY_IDENTIFIER ::= ON | OFF | CHECK | DISABLE | IGNORE
This pragma is used to set the checking policy for assertions (specified
by aspects or pragmas), the `Debug' pragma, or additional checks to be
checked using the `Check' pragma. It may appear either as a
configuration pragma, or within a declarative part of package. In the
latter case, it applies from the point where it appears to the end of
the declarative region (like pragma `Suppress').
The `Check_Policy' pragma is similar to the predefined
`Assertion_Policy' pragma, and if the check kind corresponds to one of
the assertion kinds that are allowed by `Assertion_Policy', then the
effect is identical.
If the first argument is Debug, then the policy applies to Debug
pragmas, disabling their effect if the policy is `OFF', `DISABLE', or
`IGNORE', and allowing them to execute with normal semantics if the
policy is `ON' or `CHECK'. In addition if the policy is `DISABLE', then
the procedure call in `Debug' pragmas will be totally ignored and not
analyzed semantically.
Finally the first argument may be some other identifier than the above
possibilities, in which case it controls a set of named assertions that
can be checked using pragma `Check'. For example, if the pragma:
pragma Check_Policy (Critical_Error, OFF);
is given, then subsequent `Check' pragmas whose first argument is also
`Critical_Error' will be disabled.
The check policy is `OFF' to turn off corresponding checks, and `ON' to
turn on corresponding checks. The default for a set of checks for which
no `Check_Policy' is given is `OFF' unless the compiler switch `-gnata'
is given, which turns on all checks by default.
The check policy settings `CHECK' and `IGNORE' are recognized as
synonyms for `ON' and `OFF'. These synonyms are provided for
compatibility with the standard `Assertion_Policy' pragma. The check
policy setting `DISABLE' causes the second argument of a corresponding
`Check' pragma to be completely ignored and not analyzed.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Comment" origin="GNAT RM">
<DOC>Syntax:
pragma Comment (static_string_EXPRESSION);
This is almost identical in effect to pragma `Ident'. It allows the
placement of a comment into the object file and hence into the
executable file if the operating system permits such usage. The
difference is that `Comment', unlike `Ident', has no limitations on
placement of the pragma (it can be placed anywhere in the main source
unit), and if more than one pragma is used, all comments are retained.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Common_Object" origin="GNAT RM">
<DOC>Syntax:
pragma Common_Object (
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Size =&gt;] EXTERNAL_SYMBOL] );
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
This pragma enables the shared use of variables stored in overlaid
linker areas corresponding to the use of `COMMON' in Fortran. The
single object `LOCAL_NAME' is assigned to the area designated by the
`External' argument. You may define a record to correspond to a series
of fields. The `Size' argument is syntax checked in GNAT, but
otherwise ignored.
`Common_Object' is not supported on all platforms. If no support is
available, then the code generator will issue a message indicating that
the necessary attribute for implementation of this pragma is not
available.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Compile_Time_Error" origin="GNAT RM">
<DOC>Syntax:
pragma Compile_Time_Error
(boolean_EXPRESSION, static_string_EXPRESSION);
This pragma can be used to generate additional compile time error
messages. It is particularly useful in generics, where errors can be
issued for specific problematic instantiations. The first parameter is
a boolean expression. The pragma ensures that the value of an expression
is known at compile time, and has the value False. The set of
expressions whose values are known at compile time includes all static
boolean expressions, and also other values which the compiler can
determine at compile time (e.g., the size of a record type set by an
explicit size representation clause, or the value of a variable which
was initialized to a constant and is known not to have been modified).
If these conditions are not met, an error message is generated using
the value given as the second argument. This string value may contain
embedded ASCII.LF characters to break the message into multiple lines.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Compile_Time_Warning" origin="GNAT RM">
<DOC>Syntax:
pragma Compile_Time_Warning
(boolean_EXPRESSION, static_string_EXPRESSION);
Same as pragma Compile_Time_Error, except a warning is issued instead
of an error message. If switch `-gnatw_C' is used, a warning is only
issued if the value of the expression is known to be True at compile
time, not when the value of the expression is not known at compile time.
Note that if this pragma is used in a package that is with'ed by a
client, the client will get the warning even though it is issued by a
with'ed package (normally warnings in with'ed units are suppressed, but
this is a special exception to that rule).
One typical use is within a generic where compile time known
characteristics of formal parameters are tested, and warnings given
appropriately. Another use with a first parameter of True is to warn a
client about use of a package, for example that it is not fully
implemented.
In previous versions of the compiler, combining `-gnatwe' with
Compile_Time_Warning resulted in a fatal error. Now the compiler always
emits a warning. You can use *note Pragma Compile_Time_Error: 3a. to
force the generation of an error.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Compiler_Unit" origin="GNAT RM">
<DOC>Syntax:
pragma Compiler_Unit;
This pragma is obsolete. It is equivalent to Compiler_Unit_Warning. It
is retained so that old versions of the GNAT run-time that use this
pragma can be compiled with newer versions of the compiler.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Compiler_Unit_Warning" origin="GNAT RM">
<DOC>Syntax:
pragma Compiler_Unit_Warning;
This pragma is intended only for internal use in the GNAT run-time
library. It indicates that the unit is used as part of the compiler
build. The effect is to generate warnings for the use of constructs
(for example, conditional expressions) that would cause trouble when
bootstrapping using an older version of GNAT. For the exact list of
restrictions, see the compiler sources and references to
Check_Compiler_Unit.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Complete_Representation" origin="GNAT RM">
<DOC>Syntax:
pragma Complete_Representation;
This pragma must appear immediately within a record representation
clause. Typical placements are before the first component clause or
after the last component clause. The effect is to give an error message
if any component is missing a component clause. This pragma may be used
to ensure that a record representation clause is complete, and that
this invariant is maintained if fields are added to the record in the
future.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Complex_Representation" origin="GNAT RM">
<DOC>Syntax:
pragma Complex_Representation
([Entity =&gt;] LOCAL_NAME);
The `Entity' argument must be the name of a record type which has two
fields of the same floating-point type. The effect of this pragma is
to force gcc to use the special internal complex representation form for
this record, which may be more efficient. Note that this may result in
the code for this type not conforming to standard ABI (application
binary interface) requirements for the handling of record types. For
example, in some environments, there is a requirement for passing
records by pointer, and the use of this pragma may result in passing
this type in floating-point registers.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Component_Alignment" origin="GNAT RM">
<DOC>Syntax:
pragma Component_Alignment (
[Form =&gt;] ALIGNMENT_CHOICE
[, [Name =&gt;] type_LOCAL_NAME]);
ALIGNMENT_CHOICE ::=
Component_Size
| Component_Size_4
| Storage_Unit
| Default
Specifies the alignment of components in array or record types. The
meaning of the `Form' argument is as follows:
`Component_Size'
Aligns scalar components and subcomponents of the array or record
type on boundaries appropriate to their inherent size (naturally
aligned). For example, 1-byte components are aligned on byte
boundaries, 2-byte integer components are aligned on 2-byte
boundaries, 4-byte integer components are aligned on 4-byte
boundaries and so on. These alignment rules correspond to the
normal rules for C compilers on all machines except the VAX.
`Component_Size_4'
Naturally aligns components with a size of four or fewer bytes.
Components that are larger than 4 bytes are placed on the next
-byte boundary.
`Storage_Unit'
Specifies that array or record components are byte aligned, i.e.,
aligned on boundaries determined by the value of the constant
`System.Storage_Unit'.
`Default'
Specifies that array or record components are aligned on default
boundaries, appropriate to the underlying hardware or operating
system or both. The `Default' choice is the same as
`Component_Size' (natural alignment).
If the `Name' parameter is present, `type_LOCAL_NAME' must refer to a
local record or array type, and the specified alignment choice applies
to the specified type. The use of `Component_Alignment' together with
a pragma `Pack' causes the `Component_Alignment' pragma to be ignored.
The use of `Component_Alignment' together with a record representation
clause is only effective for fields not specified by the representation
clause.
If the `Name' parameter is absent, the pragma can be used as either a
configuration pragma, in which case it applies to one or more units in
accordance with the normal rules for configuration pragmas, or it can be
used within a declarative part, in which case it applies to types that
are declared within this declarative part, or within any nested scope
within this declarative part. In either case it specifies the alignment
to be applied to any record or array type which has otherwise standard
representation.
If the alignment for a record or array type is not specified (using
pragma `Pack', pragma `Component_Alignment', or a record rep clause),
the GNAT uses the default alignment as described previously.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Constant_After_Elaboration" origin="GNAT RM">
<DOC>Syntax:
pragma Constant_After_Elaboration [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Constant_After_Elaboration' in the SPARK 2014 Reference Manual,
section 3.3.1.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Contract_Cases" origin="GNAT RM">
<DOC>Syntax:
pragma Contract_Cases ((CONTRACT_CASE {, CONTRACT_CASE));
CONTRACT_CASE ::= CASE_GUARD =&gt; CONSEQUENCE
CASE_GUARD ::= boolean_EXPRESSION | others
CONSEQUENCE ::= boolean_EXPRESSION
The `Contract_Cases' pragma allows defining fine-grain specifications
that can complement or replace the contract given by a precondition and
a postcondition. Additionally, the `Contract_Cases' pragma can be used
by testing and formal verification tools. The compiler checks its
validity and, depending on the assertion policy at the point of
declaration of the pragma, it may insert a check in the executable. For
code generation, the contract cases
pragma Contract_Cases (
Cond1 =&gt; Pred1,
Cond2 =&gt; Pred2);
are equivalent to
C1 : constant Boolean := Cond1; -- evaluated at subprogram entry
C2 : constant Boolean := Cond2; -- evaluated at subprogram entry
pragma Precondition ((C1 and not C2) or (C2 and not C1));
pragma Postcondition (if C1 then Pred1);
pragma Postcondition (if C2 then Pred2);
The precondition ensures that one and only one of the case guards is
satisfied on entry to the subprogram. The postcondition ensures that
for the case guard that was True on entry, the corresponding
consequence is True on exit. Other consequence expressions are not
evaluated.
A precondition `P' and postcondition `Q' can also be expressed as
contract cases:
pragma Contract_Cases (P =&gt; Q);
The placement and visibility rules for `Contract_Cases' pragmas are
identical to those described for preconditions and postconditions.
The compiler checks that boolean expressions given in case guards and
consequences are valid, where the rules for case guards are the same as
the rule for an expression in `Precondition' and the rules for
consequences are the same as the rule for an expression in
`Postcondition'. In particular, attributes `'Old' and `'Result' can
only be used within consequence expressions. The case guard for the
last contract case may be `others', to denote any case not captured by
the previous cases. The following is an example of use within a package
spec:
package Math_Functions is
function Sqrt (Arg : Float) return Float;
pragma Contract_Cases (((Arg in 0.0 .. 99.0) =&gt; Sqrt'Result &lt; 10.0,
Arg &gt;= 100.0 =&gt; Sqrt'Result &gt;= 10.0,
others =&gt; Sqrt'Result = 0.0));
end Math_Functions;
The meaning of contract cases is that only one case should apply at each
call, as determined by the corresponding case guard evaluating to True,
and that the consequence for this case should hold when the subprogram
returns.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Convention" origin="Ada RM">
<DOC>Syntax:
pragma Convention ([Convention=&gt;]convention_identifier,[Entity=&gt;]local_name);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Convention_Identifier" origin="GNAT RM">
<DOC>Syntax:
pragma Convention_Identifier (
[Name =&gt;] IDENTIFIER,
[Convention =&gt;] convention_IDENTIFIER);
This pragma provides a mechanism for supplying synonyms for existing
convention identifiers. The `Name' identifier can subsequently be used
as a synonym for the given convention in other pragmas (including for
example pragma `Import' or another `Convention_Identifier' pragma). As
an example of the use of this, suppose you had legacy code which used
Fortran77 as the identifier for Fortran. Then the pragma:
pragma Convention_Identifier (Fortran77, Fortran);
would allow the use of the convention identifier `Fortran77' in
subsequent code, avoiding the need to modify the sources. As another
example, you could use this to parameterize convention requirements
according to systems. Suppose you needed to use `Stdcall' on windows
systems, and `C' on some other system, then you could define a
convention identifier `Library' and use a single
`Convention_Identifier' pragma to specify which convention would be
used system-wide.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Deadline_Floor" origin="GNAT RM">
<DOC>Syntax:
pragma Deadline_Floor (time_span_EXPRESSION);
This pragma applies only to protected types and specifies the floor
deadline inherited by a task when the task enters a protected object.
It is effective only when the EDF scheduling policy is used.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Debug" origin="GNAT RM">
<DOC>Syntax:
pragma Debug ([CONDITION, ]PROCEDURE_CALL_WITHOUT_SEMICOLON);
PROCEDURE_CALL_WITHOUT_SEMICOLON ::=
PROCEDURE_NAME
| PROCEDURE_PREFIX ACTUAL_PARAMETER_PART
The procedure call argument has the syntactic form of an expression,
meeting the syntactic requirements for pragmas.
If debug pragmas are not enabled or if the condition is present and
evaluates to False, this pragma has no effect. If debug pragmas are
enabled, the semantics of the pragma is exactly equivalent to the
procedure call statement corresponding to the argument with a
terminating semicolon. Pragmas are permitted in sequences of
declarations, so you can use pragma `Debug' to intersperse calls to
debug procedures in the middle of declarations. Debug pragmas can be
enabled either by use of the command line switch `-gnata' or by use of
the pragma `Check_Policy' with a first argument of `Debug'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Debug_Policy" origin="GNAT RM">
<DOC>Syntax:
pragma Debug_Policy (CHECK | DISABLE | IGNORE | ON | OFF);
This pragma is equivalent to a corresponding `Check_Policy' pragma with
a first argument of `Debug'. It is retained for historical
compatibility reasons.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Default_Initial_Condition" origin="GNAT RM">
<DOC>Syntax:
pragma Default_Initial_Condition [ (null | boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Default_Initial_Condition' in the SPARK 2014 Reference Manual, section
7.3.3.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Default_Scalar_Storage_Order" origin="GNAT RM">
<DOC>Syntax:
pragma Default_Scalar_Storage_Order (High_Order_First | Low_Order_First);
Normally if no explicit `Scalar_Storage_Order' is given for a record
type or array type, then the scalar storage order defaults to the
ordinary default for the target. But this default may be overridden
using this pragma. The pragma may appear as a configuration pragma, or
locally within a package spec or declarative part. In the latter case,
it applies to all subsequent types declared within that package spec or
declarative part.
The following example shows the use of this pragma:
pragma Default_Scalar_Storage_Order (High_Order_First);
with System; use System;
package DSSO1 is
type H1 is record
a : Integer;
end record;
type L2 is record
a : Integer;
end record;
for L2'Scalar_Storage_Order use Low_Order_First;
type L2a is new L2;
package Inner is
type H3 is record
a : Integer;
end record;
pragma Default_Scalar_Storage_Order (Low_Order_First);
type L4 is record
a : Integer;
end record;
end Inner;
type H4a is new Inner.L4;
type H5 is record
a : Integer;
end record;
end DSSO1;
In this example record types with names starting with `L' have
`Low_Order_First' scalar storage order, and record types with names
starting with `H' have `High_Order_First'. Note that in the case of
`H4a', the order is not inherited from the parent type. Only an
explicitly set `Scalar_Storage_Order' gets inherited on type derivation.
If this pragma is used as a configuration pragma which appears within a
configuration pragma file (as opposed to appearing explicitly at the
start of a single unit), then the binder will require that all units in
a partition be compiled in a similar manner, other than run-time units,
which are not affected by this pragma. Note that the use of this form
is discouraged because it may significantly degrade the run-time
performance of the software, instead the default scalar storage order
ought to be changed only on a local basis.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Default_Storage_Pool" origin="GNAT RM">
<DOC>Syntax:
pragma Default_Storage_Pool (storage_pool_NAME | null);
This pragma is standard in Ada 2012, but is available in all earlier
versions of Ada as an implementation-defined pragma. See Ada 2012
Reference Manual for details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Depends" origin="GNAT RM">
<DOC>Syntax:
pragma Depends (DEPENDENCY_RELATION);
DEPENDENCY_RELATION ::=
null
| (DEPENDENCY_CLAUSE {, DEPENDENCY_CLAUSE})
DEPENDENCY_CLAUSE ::=
OUTPUT_LIST =&gt;[+] INPUT_LIST
| NULL_DEPENDENCY_CLAUSE
NULL_DEPENDENCY_CLAUSE ::= null =&gt; INPUT_LIST
OUTPUT_LIST ::= OUTPUT | (OUTPUT {, OUTPUT})
INPUT_LIST ::= null | INPUT | (INPUT {, INPUT})
OUTPUT ::= NAME | FUNCTION_RESULT
INPUT ::= NAME
where FUNCTION_RESULT is a function Result attribute_reference
For the semantics of this pragma, see the entry for aspect `Depends' in
the SPARK 2014 Reference Manual, section 6.1.5.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Detect_Blocking" origin="GNAT RM">
<DOC>Syntax:
pragma Detect_Blocking;
This is a standard pragma in Ada 2005, that is available in all earlier
versions of Ada as an implementation-defined pragma.
This is a configuration pragma that forces the detection of potentially
blocking operations within a protected operation, and to raise
Program_Error if that happens.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Disable_Atomic_Synchronization" origin="GNAT RM">
<DOC>Syntax:
pragma Disable_Atomic_Synchronization [(Entity)];
Ada requires that accesses (reads or writes) of an atomic variable be
regarded as synchronization points in the case of multiple tasks.
Particularly in the case of multi-processors this may require special
handling, e.g. the generation of memory barriers. This capability may
be turned off using this pragma in cases where it is known not to be
required.
The placement and scope rules for this pragma are the same as those for
`pragma Suppress'. In particular it can be used as a configuration
pragma, or in a declaration sequence where it applies till the end of
the scope. If an `Entity' argument is present, the action applies only
to that entity.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Discard_Names" origin="Ada RM">
<DOC>Syntax:
pragma Discard_Names [([On =&gt; ] local_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Dispatching_Domain" origin="GNAT RM">
<DOC>Syntax:
pragma Dispatching_Domain (EXPRESSION);
This pragma is standard in Ada 2012, but is available in all earlier
versions of Ada as an implementation-defined pragma. See Ada 2012
Reference Manual for details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Effective_Reads" origin="GNAT RM">
<DOC>Syntax:
pragma Effective_Reads [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Effective_Reads' in the SPARK 2014 Reference Manual, section 7.1.2.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Effective_Writes" origin="GNAT RM">
<DOC>Syntax:
pragma Effective_Writes [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Effective_Writes' in the SPARK 2014 Reference Manual, section 7.1.2.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Elaborate" origin="Ada RM">
<DOC>Syntax:
pragma Elaborate (library_unit_name{, library_unit_name});</DOC>
</PRAGMA>
<PRAGMA id="0" name="Elaborate_All" origin="Ada RM">
<DOC>Syntax:
pragma Elaborate_All (library_unit_name{, library_unit_name});</DOC>
</PRAGMA>
<PRAGMA id="0" name="Elaborate_Body" origin="Ada RM">
<DOC>Syntax:
pragma Elaborate_Body [(library_unit_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Elaboration_Checks" origin="GNAT RM">
<DOC>Syntax:
pragma Elaboration_Checks (Dynamic | Static);
This is a configuration pragma which specifies the elaboration model to
be used during compilation. For more information on the elaboration
models of GNAT, consult the chapter on elaboration order handling in
the `GNAT User's Guide'.
The pragma may appear in the following contexts:
* Configuration pragmas file
* Prior to the context clauses of a compilation unit's initial
declaration
Any other placement of the pragma will result in a warning and the
effects of the offending pragma will be ignored.
If the pragma argument is `Dynamic', then the dynamic elaboration model
is in effect. If the pragma argument is `Static', then the static
elaboration model is in effect.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Eliminate" origin="GNAT RM">
<DOC>Syntax:
pragma Eliminate (
[ Unit_Name =&gt; ] IDENTIFIER | SELECTED_COMPONENT ,
[ Entity =&gt; ] IDENTIFIER |
SELECTED_COMPONENT |
STRING_LITERAL
[, Source_Location =&gt; SOURCE_TRACE ] );
SOURCE_TRACE ::= STRING_LITERAL
This pragma indicates that the given entity is not used in the program
to be compiled and built, thus allowing the compiler to eliminate the
code or data associated with the named entity. Any reference to an
eliminated entity causes a compile-time or link-time error.
The pragma has the following semantics, where `U' is the unit specified
by the `Unit_Name' argument and `E' is the entity specified by the
`Entity' argument:
* `E' must be a subprogram that is explicitly declared either:
o Within `U', or
o Within a generic package that is instantiated in `U', or
o As an instance of generic subprogram instantiated in `U'.
Otherwise the pragma is ignored.
* If `E' is overloaded within `U' then, in the absence of a
`Source_Location' argument, all overloadings are eliminated.
* If `E' is overloaded within `U' and only some overloadings are to
be eliminated, then each overloading to be eliminated must be
specified in a corresponding pragma `Eliminate' with a
`Source_Location' argument identifying the line where the
declaration appears, as described below.
* If `E' is declared as the result of a generic instantiation, then
a `Source_Location' argument is needed, as described below
Pragma `Eliminate' allows a program to be compiled in a
system-independent manner, so that unused entities are eliminated but
without needing to modify the source text. Normally the required set of
`Eliminate' pragmas is constructed automatically using the `gnatelim'
tool.
Any source file change that removes, splits, or adds lines may make the
set of `Eliminate' pragmas invalid because their `Source_Location'
argument values may get out of date.
Pragma `Eliminate' may be used where the referenced entity is a
dispatching operation. In this case all the subprograms to which the
given operation can dispatch are considered to be unused (are never
called as a result of a direct or a dispatching call).
The string literal given for the source location specifies the line
number of the declaration of the entity, using the following syntax for
`SOURCE_TRACE':
SOURCE_TRACE ::= SOURCE_REFERENCE [ LBRACKET SOURCE_TRACE RBRACKET ]
LBRACKET ::= '['
RBRACKET ::= ']'
SOURCE_REFERENCE ::= FILE_NAME : LINE_NUMBER
LINE_NUMBER ::= DIGIT {DIGIT}
Spaces around the colon in a `SOURCE_REFERENCE' are optional.
The source trace that is given as the `Source_Location' must obey the
following rules (or else the pragma is ignored), where `U' is the unit
`U' specified by the `Unit_Name' argument and `E' is the subprogram
specified by the `Entity' argument:
* `FILE_NAME' is the short name (with no directory information) of
the Ada source file for `U', using the required syntax for the
underlying file system (e.g. case is significant if the underlying
operating system is case sensitive). If `U' is a package and `E'
is a subprogram declared in the package specification and its full
declaration appears in the package body, then the relevant source
file is the one for the package specification; analogously if `U'
is a generic package.
* If `E' is not declared in a generic instantiation (this includes
generic subprogram instances), the source trace includes only one
source line reference. `LINE_NUMBER' gives the line number of the
occurrence of the declaration of `E' within the source file (as a
decimal literal without an exponent or point).
* If `E' is declared by a generic instantiation, its source trace
(from left to right) starts with the source location of the
declaration of `E' in the generic unit and ends with the source
location of the instantiation, given in square brackets. This
approach is applied recursively with nested instantiations: the
rightmost (nested most deeply in square brackets) element of the
source trace is the location of the outermost instantiation, and
the leftmost element (that is, outside of any square brackets) is
the location of the declaration of `E' in the generic unit.
Examples:
pragma Eliminate (Pkg0, Proc);
-- Eliminate (all overloadings of) Proc in Pkg0
pragma Eliminate (Pkg1, Proc,
Source_Location =&gt; "pkg1.ads:8");
-- Eliminate overloading of Proc at line 8 in pkg1.ads
-- Assume the following file contents:
-- gen_pkg.ads
-- 1: generic
-- 2: type T is private;
-- 3: package Gen_Pkg is
-- 4: procedure Proc(N : T);
-- ... ...
-- ... end Gen_Pkg;
--
-- q.adb
-- 1: with Gen_Pkg;
-- 2: procedure Q is
-- 3: package Inst_Pkg is new Gen_Pkg(Integer);
-- ... -- No calls on Inst_Pkg.Proc
-- ... end Q;
-- The following pragma eliminates Inst_Pkg.Proc from Q
pragma Eliminate (Q, Proc,
Source_Location =&gt; "gen_pkg.ads:4[q.adb:3]");</DOC>
</PRAGMA>
<PRAGMA id="0" name="Enable_Atomic_Synchronization" origin="GNAT RM">
<DOC>Syntax:
pragma Enable_Atomic_Synchronization [(Entity)];
Ada requires that accesses (reads or writes) of an atomic variable be
regarded as synchronization points in the case of multiple tasks.
Particularly in the case of multi-processors this may require special
handling, e.g. the generation of memory barriers. This synchronization
is performed by default, but can be turned off using `pragma
Disable_Atomic_Synchronization'. The `Enable_Atomic_Synchronization'
pragma can be used to turn it back on.
The placement and scope rules for this pragma are the same as those for
`pragma Unsuppress'. In particular it can be used as a configuration
pragma, or in a declaration sequence where it applies till the end of
the scope. If an `Entity' argument is present, the action applies only
to that entity.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Export" origin="Ada RM">
<DOC>Syntax:
pragma Export ([Convention=&gt;]convention_identifier,[Entity=&gt;]local_name;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Export_Function" origin="GNAT RM">
<DOC>Syntax:
pragma Export_Function (
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Parameter_Types =&gt;] PARAMETER_TYPES]
[, [Result_Type =&gt;] result_SUBTYPE_MARK]
[, [Mechanism =&gt;] MECHANISM]
[, [Result_Mechanism =&gt;] MECHANISM_NAME]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
| ""
PARAMETER_TYPES ::=
null
| TYPE_DESIGNATOR {, TYPE_DESIGNATOR}
TYPE_DESIGNATOR ::=
subtype_NAME
| subtype_Name ' Access
MECHANISM ::=
MECHANISM_NAME
| (MECHANISM_ASSOCIATION {, MECHANISM_ASSOCIATION})
MECHANISM_ASSOCIATION ::=
[formal_parameter_NAME =&gt;] MECHANISM_NAME
MECHANISM_NAME ::= Value | Reference
Use this pragma to make a function externally callable and optionally
provide information on mechanisms to be used for passing parameter and
result values. We recommend, for the purposes of improving portability,
this pragma always be used in conjunction with a separate pragma
`Export', which must precede the pragma `Export_Function'. GNAT does
not require a separate pragma `Export', but if none is present,
`Convention Ada' is assumed, which is usually not what is wanted, so it
is usually appropriate to use this pragma in conjunction with a
`Export' or `Convention' pragma that specifies the desired foreign
convention. Pragma `Export_Function' (and `Export', if present) must
appear in the same declarative region as the function to which they
apply.
The `internal_name' must uniquely designate the function to which the
pragma applies. If more than one function name exists of this name in
the declarative part you must use the `Parameter_Types' and
`Result_Type' parameters to achieve the required unique designation.
The `subtype_mark's in these parameters must exactly match the subtypes
in the corresponding function specification, using positional notation
to match parameters with subtype marks. The form with an `'Access'
attribute can be used to match an anonymous access parameter.
Special treatment is given if the EXTERNAL is an explicit null string
or a static string expressions that evaluates to the null string. In
this case, no external name is generated. This form still allows the
specification of parameter mechanisms.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Export_Object" origin="GNAT RM">
<DOC>Syntax:
pragma Export_Object
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Size =&gt;] EXTERNAL_SYMBOL]
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
This pragma designates an object as exported, and apart from the
extended rules for external symbols, is identical in effect to the use
of the normal `Export' pragma applied to an object. You may use a
separate Export pragma (and you probably should from the point of view
of portability), but it is not required. `Size' is syntax checked, but
otherwise ignored by GNAT.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Export_Procedure" origin="GNAT RM">
<DOC>Syntax:
pragma Export_Procedure (
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Parameter_Types =&gt;] PARAMETER_TYPES]
[, [Mechanism =&gt;] MECHANISM]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
| ""
PARAMETER_TYPES ::=
null
| TYPE_DESIGNATOR {, TYPE_DESIGNATOR}
TYPE_DESIGNATOR ::=
subtype_NAME
| subtype_Name ' Access
MECHANISM ::=
MECHANISM_NAME
| (MECHANISM_ASSOCIATION {, MECHANISM_ASSOCIATION})
MECHANISM_ASSOCIATION ::=
[formal_parameter_NAME =&gt;] MECHANISM_NAME
MECHANISM_NAME ::= Value | Reference
This pragma is identical to `Export_Function' except that it applies to
a procedure rather than a function and the parameters `Result_Type' and
`Result_Mechanism' are not permitted. GNAT does not require a separate
pragma `Export', but if none is present, `Convention Ada' is assumed,
which is usually not what is wanted, so it is usually appropriate to
use this pragma in conjunction with a `Export' or `Convention' pragma
that specifies the desired foreign convention.
Special treatment is given if the EXTERNAL is an explicit null string
or a static string expressions that evaluates to the null string. In
this case, no external name is generated. This form still allows the
specification of parameter mechanisms.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Export_Value" origin="GNAT RM">
<DOC>Syntax:
pragma Export_Value (
[Value =&gt;] static_integer_EXPRESSION,
[Link_Name =&gt;] static_string_EXPRESSION);
This pragma serves to export a static integer value for external use.
The first argument specifies the value to be exported. The Link_Name
argument specifies the symbolic name to be associated with the integer
value. This pragma is useful for defining a named static value in Ada
that can be referenced in assembly language units to be linked with the
application. This pragma is currently supported only for the AAMP
target and is ignored for other targets.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Export_Valued_Procedure" origin="GNAT RM">
<DOC>Syntax:
pragma Export_Valued_Procedure (
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Parameter_Types =&gt;] PARAMETER_TYPES]
[, [Mechanism =&gt;] MECHANISM]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
| ""
PARAMETER_TYPES ::=
null
| TYPE_DESIGNATOR {, TYPE_DESIGNATOR}
TYPE_DESIGNATOR ::=
subtype_NAME
| subtype_Name ' Access
MECHANISM ::=
MECHANISM_NAME
| (MECHANISM_ASSOCIATION {, MECHANISM_ASSOCIATION})
MECHANISM_ASSOCIATION ::=
[formal_parameter_NAME =&gt;] MECHANISM_NAME
MECHANISM_NAME ::= Value | Reference
This pragma is identical to `Export_Procedure' except that the first
parameter of `LOCAL_NAME', which must be present, must be of mode
`out', and externally the subprogram is treated as a function with this
parameter as the result of the function. GNAT provides for this
capability to allow the use of `out' and `in out' parameters in
interfacing to external functions (which are not permitted in Ada
functions). GNAT does not require a separate pragma `Export', but if
none is present, `Convention Ada' is assumed, which is almost certainly
not what is wanted since the whole point of this pragma is to interface
with foreign language functions, so it is usually appropriate to use
this pragma in conjunction with a `Export' or `Convention' pragma that
specifies the desired foreign convention.
Special treatment is given if the EXTERNAL is an explicit null string
or a static string expressions that evaluates to the null string. In
this case, no external name is generated. This form still allows the
specification of parameter mechanisms.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Extend_System" origin="GNAT RM">
<DOC>Syntax:
pragma Extend_System ([Name =&gt;] IDENTIFIER);
This pragma is used to provide backwards compatibility with other
implementations that extend the facilities of package `System'. In
GNAT, `System' contains only the definitions that are present in the
Ada RM. However, other implementations, notably the DEC Ada 83
implementation, provide many extensions to package `System'.
For each such implementation accommodated by this pragma, GNAT provides
a package `Aux_`xxx'', e.g., `Aux_DEC' for the DEC Ada 83
implementation, which provides the required additional definitions. You
can use this package in two ways. You can `with' it in the normal way
and access entities either by selection or using a `use' clause. In
this case no special processing is required.
However, if existing code contains references such as `System.`xxx''
where `xxx' is an entity in the extended definitions provided in
package `System', you may use this pragma to extend visibility in
`System' in a non-standard way that provides greater compatibility with
the existing code. Pragma `Extend_System' is a configuration pragma
whose single argument is the name of the package containing the
extended definition (e.g., `Aux_DEC' for the DEC Ada case). A unit
compiled under control of this pragma will be processed using special
visibility processing that looks in package `System.Aux_`xxx'' where
`Aux_`xxx'' is the pragma argument for any entity referenced in package
`System', but not found in package `System'.
You can use this pragma either to access a predefined `System'
extension supplied with the compiler, for example `Aux_DEC' or you can
construct your own extension unit following the above definition. Note
that such a package is a child of `System' and thus is considered part
of the implementation. To compile it you will have to use the `-gnatg'
switch for compiling System units, as explained in the GNAT User's
Guide.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Extensions_Allowed" origin="GNAT RM">
<DOC>Syntax:
pragma Extensions_Allowed (On | Off);
This configuration pragma enables or disables the implementation
extension mode (the use of Off as a parameter cancels the effect of the
`-gnatX' command switch).
In extension mode, the latest version of the Ada language is
implemented (currently Ada 202x), and in addition a small number of
GNAT specific extensions are recognized as follows:
* Constrained attribute for generic objects
The `Constrained' attribute is permitted for objects of generic
types. The result indicates if the corresponding actual is
constrained.
* `Static' aspect on intrinsic functions
The Ada 202x `Static' aspect can be specified on Intrinsic imported
functions and the compiler will evaluate some of these intrinsic
statically, in particular the `Shift_Left' and `Shift_Right'
intrinsics.
* `'Reduce' attribute
This attribute part of the Ada 202x language definition is
provided for now under -gnatX to confirm and potentially refine
its usage and syntax.
* `[]' aggregates
This new aggregate syntax for arrays and containers is provided
under -gnatX to experiment and confirm this new language syntax.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Extensions_Visible" origin="GNAT RM">
<DOC>Syntax:
pragma Extensions_Visible [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Extensions_Visible' in the SPARK 2014 Reference Manual, section 6.1.7.</DOC>
</PRAGMA>
<PRAGMA id="0" name="External" origin="GNAT RM">
<DOC>Syntax:
pragma External (
[ Convention =&gt;] convention_IDENTIFIER,
[ Entity =&gt;] LOCAL_NAME
[, [External_Name =&gt;] static_string_EXPRESSION ]
[, [Link_Name =&gt;] static_string_EXPRESSION ]);
This pragma is identical in syntax and semantics to pragma `Export' as
defined in the Ada Reference Manual. It is provided for compatibility
with some Ada 83 compilers that used this pragma for exactly the same
purposes as pragma `Export' before the latter was standardized.</DOC>
</PRAGMA>
<PRAGMA id="0" name="External_Name_Casing" origin="GNAT RM">
<DOC>Syntax:
pragma External_Name_Casing (
Uppercase | Lowercase
[, Uppercase | Lowercase | As_Is]);
This pragma provides control over the casing of external names
associated with Import and Export pragmas. There are two cases to
consider:
* Implicit external names
Implicit external names are derived from identifiers. The most
common case arises when a standard Ada Import or Export pragma is
used with only two arguments, as in:
pragma Import (C, C_Routine);
Since Ada is a case-insensitive language, the spelling of the
identifier in the Ada source program does not provide any
information on the desired casing of the external name, and so a
convention is needed. In GNAT the default treatment is that such
names are converted to all lower case letters. This corresponds
to the normal C style in many environments. The first argument of
pragma `External_Name_Casing' can be used to control this
treatment. If `Uppercase' is specified, then the name will be
forced to all uppercase letters. If `Lowercase' is specified,
then the normal default of all lower case letters will be used.
This same implicit treatment is also used in the case of extended
DEC Ada 83 compatible Import and Export pragmas where an external
name is explicitly specified using an identifier rather than a
string.
* Explicit external names
Explicit external names are given as string literals. The most
common case arises when a standard Ada Import or Export pragma is
used with three arguments, as in:
pragma Import (C, C_Routine, "C_routine");
In this case, the string literal normally provides the exact
casing required for the external name. The second argument of
pragma `External_Name_Casing' may be used to modify this behavior.
If `Uppercase' is specified, then the name will be forced to all
uppercase letters. If `Lowercase' is specified, then the name
will be forced to all lowercase letters. A specification of
`As_Is' provides the normal default behavior in which the casing is
taken from the string provided.
This pragma may appear anywhere that a pragma is valid. In particular,
it can be used as a configuration pragma in the `gnat.adc' file, in
which case it applies to all subsequent compilations, or it can be used
as a program unit pragma, in which case it only applies to the current
unit, or it can be used more locally to control individual
Import/Export pragmas.
It was primarily intended for use with OpenVMS systems, where many
compilers convert all symbols to upper case by default. For
interfacing to such compilers (e.g., the DEC C compiler), it may be
convenient to use the pragma:
pragma External_Name_Casing (Uppercase, Uppercase);
to enforce the upper casing of all external symbols.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Fast_Math" origin="GNAT RM">
<DOC>Syntax:
pragma Fast_Math;
This is a configuration pragma which activates a mode in which speed is
considered more important for floating-point operations than absolutely
accurate adherence to the requirements of the standard. Currently the
following operations are affected:
`Complex Multiplication'
The normal simple formula for complex multiplication can result in
intermediate overflows for numbers near the end of the range. The
Ada standard requires that this situation be detected and
corrected by scaling, but in Fast_Math mode such cases will simply
result in overflow. Note that to take advantage of this you must
instantiate your own version of
`Ada.Numerics.Generic_Complex_Types' under control of the pragma,
rather than use the preinstantiated versions.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Favor_Top_Level" origin="GNAT RM">
<DOC>Syntax:
pragma Favor_Top_Level (type_NAME);
The argument of pragma `Favor_Top_Level' must be a named
access-to-subprogram type. This pragma is an efficiency hint to the
compiler, regarding the use of `'Access' or `'Unrestricted_Access' on
nested (non-library-level) subprograms. The pragma means that nested
subprograms are not used with this type, or are rare, so that the
generated code should be efficient in the top-level case. When this
pragma is used, dynamically generated trampolines may be used on some
targets for nested subprograms. See restriction
`No_Implicit_Dynamic_Code'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Finalize_Storage_Only" origin="GNAT RM">
<DOC>Syntax:
pragma Finalize_Storage_Only (first_subtype_LOCAL_NAME);
The argument of pragma `Finalize_Storage_Only' must denote a local type
which is derived from `Ada.Finalization.Controlled' or
`Limited_Controlled'. The pragma suppresses the call to `Finalize' for
declared library-level objects of the argument type. This is mostly
useful for types where finalization is only used to deal with storage
reclamation since in most environments it is not necessary to reclaim
memory just before terminating execution, hence the name. Note that
this pragma does not suppress Finalize calls for library-level
heap-allocated objects (see pragma `No_Heap_Finalization').</DOC>
</PRAGMA>
<PRAGMA id="0" name="Float_Representation" origin="GNAT RM">
<DOC>Syntax:
pragma Float_Representation (FLOAT_REP[, float_type_LOCAL_NAME]);
FLOAT_REP ::= VAX_Float | IEEE_Float
In the one argument form, this pragma is a configuration pragma which
allows control over the internal representation chosen for the
predefined floating point types declared in the packages `Standard' and
`System'. This pragma is only provided for compatibility and has no
effect.
The two argument form specifies the representation to be used for the
specified floating-point type. The argument must be `IEEE_Float' to
specify the use of IEEE format, as follows:
* For a digits value of 6, 32-bit IEEE short format will be used.
* For a digits value of 15, 64-bit IEEE long format will be used.
* No other value of digits is permitted.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ghost" origin="GNAT RM">
<DOC>Syntax:
pragma Ghost [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect `Ghost' in
the SPARK 2014 Reference Manual, section 6.9.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Global" origin="GNAT RM">
<DOC>Syntax:
pragma Global (GLOBAL_SPECIFICATION);
GLOBAL_SPECIFICATION ::=
null
| (GLOBAL_LIST)
| (MODED_GLOBAL_LIST {, MODED_GLOBAL_LIST})
MODED_GLOBAL_LIST ::= MODE_SELECTOR =&gt; GLOBAL_LIST
MODE_SELECTOR ::= In_Out | Input | Output | Proof_In
GLOBAL_LIST ::= GLOBAL_ITEM | (GLOBAL_ITEM {, GLOBAL_ITEM})
GLOBAL_ITEM ::= NAME
For the semantics of this pragma, see the entry for aspect `Global' in
the SPARK 2014 Reference Manual, section 6.1.4.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ident" origin="GNAT RM">
<DOC>Syntax:
pragma Ident (static_string_EXPRESSION);
This pragma is identical in effect to pragma `Comment'. It is provided
for compatibility with other Ada compilers providing this pragma.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ignore_Pragma" origin="GNAT RM">
<DOC>Syntax:
pragma Ignore_Pragma (pragma_IDENTIFIER);
This is a configuration pragma that takes a single argument that is a
simple identifier. Any subsequent use of a pragma whose pragma
identifier matches this argument will be silently ignored. This may be
useful when legacy code or code intended for compilation with some
other compiler contains pragmas that match the name, but not the exact
implementation, of a GNAT pragma. The use of this pragma allows such
pragmas to be ignored, which may be useful in CodePeer mode, or during
porting of legacy code.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Implementation_Defined" origin="GNAT RM">
<DOC>Syntax:
pragma Implementation_Defined (local_NAME);
This pragma marks a previously declared entity as
implementation-defined. For an overloaded entity, applies to the most
recent homonym.
pragma Implementation_Defined;
The form with no arguments appears anywhere within a scope, most
typically a package spec, and indicates that all entities that are
defined within the package spec are Implementation_Defined.
This pragma is used within the GNAT runtime library to identify
implementation-defined entities introduced in language-defined units,
for the purpose of implementing the No_Implementation_Identifiers
restriction.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Implemented" origin="GNAT RM">
<DOC>Syntax:
pragma Implemented (procedure_LOCAL_NAME, implementation_kind);
implementation_kind ::= By_Entry | By_Protected_Procedure | By_Any
This is an Ada 2012 representation pragma which applies to protected,
task and synchronized interface primitives. The use of pragma
Implemented provides a way to impose a static requirement on the
overriding operation by adhering to one of the three implementation
kinds: entry, protected procedure or any of the above. This pragma is
available in all earlier versions of Ada as an implementation-defined
pragma.
type Synch_Iface is synchronized interface;
procedure Prim_Op (Obj : in out Iface) is abstract;
pragma Implemented (Prim_Op, By_Protected_Procedure);
protected type Prot_1 is new Synch_Iface with
procedure Prim_Op; -- Legal
end Prot_1;
protected type Prot_2 is new Synch_Iface with
entry Prim_Op; -- Illegal
end Prot_2;
task type Task_Typ is new Synch_Iface with
entry Prim_Op; -- Illegal
end Task_Typ;
When applied to the procedure_or_entry_NAME of a requeue statement,
pragma Implemented determines the runtime behavior of the requeue.
Implementation kind By_Entry guarantees that the action of requeueing
will proceed from an entry to another entry. Implementation kind
By_Protected_Procedure transforms the requeue into a dispatching call,
thus eliminating the chance of blocking. Kind By_Any shares the
behavior of By_Entry and By_Protected_Procedure depending on the
target's overriding subprogram kind.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Implicit_Packing" origin="GNAT RM">
<DOC>Syntax:
pragma Implicit_Packing;
This is a configuration pragma that requests implicit packing for packed
arrays for which a size clause is given but no explicit pragma Pack or
specification of Component_Size is present. It also applies to records
where no record representation clause is present. Consider this example:
type R is array (0 .. 7) of Boolean;
for R'Size use 8;
In accordance with the recommendation in the RM (RM 13.3(53)), a Size
clause does not change the layout of a composite object. So the Size
clause in the above example is normally rejected, since the default
layout of the array uses 8-bit components, and thus the array requires
a minimum of 64 bits.
If this declaration is compiled in a region of code covered by an
occurrence of the configuration pragma Implicit_Packing, then the Size
clause in this and similar examples will cause implicit packing and
thus be accepted. For this implicit packing to occur, the type in
question must be an array of small components whose size is known at
compile time, and the Size clause must specify the exact size that
corresponds to the number of elements in the array multiplied by the
size in bits of the component type (both single and multi-dimensioned
arrays can be controlled with this pragma).
Similarly, the following example shows the use in the record case
type r is record
a, b, c, d, e, f, g, h : boolean;
chr : character;
end record;
for r'size use 16;
Without a pragma Pack, each Boolean field requires 8 bits, so the
minimum size is 72 bits, but with a pragma Pack, 16 bits would be
sufficient. The use of pragma Implicit_Packing allows this record
declaration to compile without an explicit pragma Pack.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Import" origin="Ada RM">
<DOC>Syntax:
pragma Import ([Convention=&gt;]convention_identifier,[Entity=&gt;]local_name;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Import_Function" origin="GNAT RM">
<DOC>Syntax:
pragma Import_Function (
[Internal =&gt;] LOCAL_NAME,
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Parameter_Types =&gt;] PARAMETER_TYPES]
[, [Result_Type =&gt;] SUBTYPE_MARK]
[, [Mechanism =&gt;] MECHANISM]
[, [Result_Mechanism =&gt;] MECHANISM_NAME]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
PARAMETER_TYPES ::=
null
| TYPE_DESIGNATOR {, TYPE_DESIGNATOR}
TYPE_DESIGNATOR ::=
subtype_NAME
| subtype_Name ' Access
MECHANISM ::=
MECHANISM_NAME
| (MECHANISM_ASSOCIATION {, MECHANISM_ASSOCIATION})
MECHANISM_ASSOCIATION ::=
[formal_parameter_NAME =&gt;] MECHANISM_NAME
MECHANISM_NAME ::=
Value
| Reference
This pragma is used in conjunction with a pragma `Import' to specify
additional information for an imported function. The pragma `Import'
(or equivalent pragma `Interface') must precede the `Import_Function'
pragma and both must appear in the same declarative part as the
function specification.
The `Internal' argument must uniquely designate the function to which
the pragma applies. If more than one function name exists of this name
in the declarative part you must use the `Parameter_Types' and
`Result_Type' parameters to achieve the required unique designation.
Subtype marks in these parameters must exactly match the subtypes in
the corresponding function specification, using positional notation to
match parameters with subtype marks. The form with an `'Access'
attribute can be used to match an anonymous access parameter.
You may optionally use the `Mechanism' and `Result_Mechanism'
parameters to specify passing mechanisms for the parameters and result.
If you specify a single mechanism name, it applies to all parameters.
Otherwise you may specify a mechanism on a parameter by parameter basis
using either positional or named notation. If the mechanism is not
specified, the default mechanism is used.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Import_Object" origin="GNAT RM">
<DOC>Syntax:
pragma Import_Object
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Size =&gt;] EXTERNAL_SYMBOL]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
This pragma designates an object as imported, and apart from the
extended rules for external symbols, is identical in effect to the use
of the normal `Import' pragma applied to an object. Unlike the
subprogram case, you need not use a separate `Import' pragma, although
you may do so (and probably should do so from a portability point of
view). `size' is syntax checked, but otherwise ignored by GNAT.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Import_Procedure" origin="GNAT RM">
<DOC>Syntax:
pragma Import_Procedure (
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Parameter_Types =&gt;] PARAMETER_TYPES]
[, [Mechanism =&gt;] MECHANISM]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
PARAMETER_TYPES ::=
null
| TYPE_DESIGNATOR {, TYPE_DESIGNATOR}
TYPE_DESIGNATOR ::=
subtype_NAME
| subtype_Name ' Access
MECHANISM ::=
MECHANISM_NAME
| (MECHANISM_ASSOCIATION {, MECHANISM_ASSOCIATION})
MECHANISM_ASSOCIATION ::=
[formal_parameter_NAME =&gt;] MECHANISM_NAME
MECHANISM_NAME ::= Value | Reference
This pragma is identical to `Import_Function' except that it applies to
a procedure rather than a function and the parameters `Result_Type' and
`Result_Mechanism' are not permitted.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Import_Valued_Procedure" origin="GNAT RM">
<DOC>Syntax:
pragma Import_Valued_Procedure (
[Internal =&gt;] LOCAL_NAME
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Parameter_Types =&gt;] PARAMETER_TYPES]
[, [Mechanism =&gt;] MECHANISM]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
PARAMETER_TYPES ::=
null
| TYPE_DESIGNATOR {, TYPE_DESIGNATOR}
TYPE_DESIGNATOR ::=
subtype_NAME
| subtype_Name ' Access
MECHANISM ::=
MECHANISM_NAME
| (MECHANISM_ASSOCIATION {, MECHANISM_ASSOCIATION})
MECHANISM_ASSOCIATION ::=
[formal_parameter_NAME =&gt;] MECHANISM_NAME
MECHANISM_NAME ::= Value | Reference
This pragma is identical to `Import_Procedure' except that the first
parameter of `LOCAL_NAME', which must be present, must be of mode
`out', and externally the subprogram is treated as a function with this
parameter as the result of the function. The purpose of this
capability is to allow the use of `out' and `in out' parameters in
interfacing to external functions (which are not permitted in Ada
functions). You may optionally use the `Mechanism' parameters to
specify passing mechanisms for the parameters. If you specify a single
mechanism name, it applies to all parameters. Otherwise you may
specify a mechanism on a parameter by parameter basis using either
positional or named notation. If the mechanism is not specified, the
default mechanism is used.
Note that it is important to use this pragma in conjunction with a
separate pragma Import that specifies the desired convention, since
otherwise the default convention is Ada, which is almost certainly not
what is required.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Independent" origin="GNAT RM">
<DOC>Syntax:
pragma Independent (Local_NAME);
This pragma is standard in Ada 2012 mode (which also provides an aspect
of the same name). It is also available as an implementation-defined
pragma in all earlier versions. It specifies that the designated object
or all objects of the designated type must be independently
addressable. This means that separate tasks can safely manipulate such
objects. For example, if two components of a record are independent,
then two separate tasks may access these two components. This may place
constraints on the representation of the object (for instance
prohibiting tight packing).</DOC>
</PRAGMA>
<PRAGMA id="0" name="Independent_Components" origin="GNAT RM">
<DOC>Syntax:
pragma Independent_Components (Local_NAME);
This pragma is standard in Ada 2012 mode (which also provides an aspect
of the same name). It is also available as an implementation-defined
pragma in all earlier versions. It specifies that the components of the
designated object, or the components of each object of the designated
type, must be independently addressable. This means that separate tasks
can safely manipulate separate components in the composite object. This
may place constraints on the representation of the object (for instance
prohibiting tight packing).</DOC>
</PRAGMA>
<PRAGMA id="0" name="Initial_Condition" origin="GNAT RM">
<DOC>Syntax:
pragma Initial_Condition (boolean_EXPRESSION);
For the semantics of this pragma, see the entry for aspect
`Initial_Condition' in the SPARK 2014 Reference Manual, section 7.1.6.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Initialize_Scalars" origin="GNAT RM">
<DOC>Syntax:
pragma Initialize_Scalars
[ ( TYPE_VALUE_PAIR {, TYPE_VALUE_PAIR} ) ];
TYPE_VALUE_PAIR ::=
SCALAR_TYPE =&gt; static_EXPRESSION
SCALAR_TYPE :=
Short_Float
| Float
| Long_Float
| Long_Long_Flat
| Signed_8
| Signed_16
| Signed_32
| Signed_64
| Unsigned_8
| Unsigned_16
| Unsigned_32
| Unsigned_64
This pragma is similar to `Normalize_Scalars' conceptually but has two
important differences.
First, there is no requirement for the pragma to be used uniformly in
all units of a partition. In particular, it is fine to use this just
for some or all of the application units of a partition, without
needing to recompile the run-time library. In the case where some units
are compiled with the pragma, and some without, then a declaration of a
variable where the type is defined in package Standard or is locally
declared will always be subject to initialization, as will any
declaration of a scalar variable. For composite variables, whether the
variable is initialized may also depend on whether the package in which
the type of the variable is declared is compiled with the pragma.
The other important difference is that the programmer can control the
value used for initializing scalar objects. This effect can be achieved
in several different ways:
* At compile time, the programmer can specify the invalid value for a
particular family of scalar types using the optional arguments of
the pragma.
The compile-time approach is intended to optimize the generated
code for the pragma, by possibly using fast operations such as
`memset'. Note that such optimizations require using values where
the bytes all have the same binary representation.
* At bind time, the programmer has several options:
* Initialization with invalid values (similar to
Normalize_Scalars, though for Initialize_Scalars it is not
always possible to determine the invalid values in complex
cases like signed component fields with nonstandard sizes).
* Initialization with high values.
* Initialization with low values.
* Initialization with a specific bit pattern.
See the GNAT User's Guide for binder options for specifying these
cases.
The bind-time approach is intended to provide fast turnaround for
testing with different values, without having to recompile the
program.
* At execution time, the programmer can specify the invalid values
using an environment variable. See the GNAT User's Guide for
details.
The execution-time approach is intended to provide fast turnaround
for testing with different values, without having to recompile and
rebind the program.
Note that pragma `Initialize_Scalars' is particularly useful in
conjunction with the enhanced validity checking that is now provided in
GNAT, which checks for invalid values under more conditions. Using this
feature (see description of the `-gnatV' flag in the GNAT User's Guide)
in conjunction with pragma `Initialize_Scalars' provides a powerful new
tool to assist in the detection of problems caused by uninitialized
variables.
Note: the use of `Initialize_Scalars' has a fairly extensive effect on
the generated code. This may cause your code to be substantially
larger. It may also cause an increase in the amount of stack required,
so it is probably a good idea to turn on stack checking (see
description of stack checking in the GNAT User's Guide) when using this
pragma.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Initializes" origin="GNAT RM">
<DOC>Syntax:
pragma Initializes (INITIALIZATION_LIST);
INITIALIZATION_LIST ::=
null
| (INITIALIZATION_ITEM {, INITIALIZATION_ITEM})
INITIALIZATION_ITEM ::= name [=&gt; INPUT_LIST]
INPUT_LIST ::=
null
| INPUT
| (INPUT {, INPUT})
INPUT ::= name
For the semantics of this pragma, see the entry for aspect
`Initializes' in the SPARK 2014 Reference Manual, section 7.1.5.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Inline" origin="Ada RM">
<DOC>Syntax:
pragma Inline;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Inline_Always" origin="GNAT RM">
<DOC>Syntax:
pragma Inline_Always (NAME [, NAME]);
Similar to pragma `Inline' except that inlining is unconditional.
Inline_Always instructs the compiler to inline every direct call to the
subprogram or else to emit a compilation error, independently of any
option, in particular `-gnatn' or `-gnatN' or the optimization level.
It is an error to take the address or access of `NAME'. It is also an
error to apply this pragma to a primitive operation of a tagged type.
Thanks to such restrictions, the compiler is allowed to remove the
out-of-line body of `NAME'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Inline_Generic" origin="GNAT RM">
<DOC>Syntax:
pragma Inline_Generic (GNAME {, GNAME});
GNAME ::= generic_unit_NAME | generic_instance_NAME
This pragma is provided for compatibility with Dec Ada 83. It has no
effect in GNAT (which always inlines generics), other than to check
that the given names are all names of generic units or generic
instances.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Inspection_Point" origin="Ada RM">
<DOC>Syntax:
pragma Inspection_Point [(object_name {, object_name})];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Interface" origin="GNAT RM">
<DOC>Syntax:
pragma Interface (
[Convention =&gt;] convention_identifier,
[Entity =&gt;] local_NAME
[, [External_Name =&gt;] static_string_expression]
[, [Link_Name =&gt;] static_string_expression]);
This pragma is identical in syntax and semantics to the standard Ada
pragma `Import'. It is provided for compatibility with Ada 83. The
definition is upwards compatible both with pragma `Interface' as
defined in the Ada 83 Reference Manual, and also with some extended
implementations of this pragma in certain Ada 83 implementations. The
only difference between pragma `Interface' and pragma `Import' is that
there is special circuitry to allow both pragmas to appear for the same
subprogram entity (normally it is illegal to have multiple `Import'
pragmas. This is useful in maintaining Ada 83/Ada 95 compatibility and
is compatible with other Ada 83 compilers.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Interface_Name" origin="GNAT RM">
<DOC>Syntax:
pragma Interface_Name (
[Entity =&gt;] LOCAL_NAME
[, [External_Name =&gt;] static_string_EXPRESSION]
[, [Link_Name =&gt;] static_string_EXPRESSION]);
This pragma provides an alternative way of specifying the interface name
for an interfaced subprogram, and is provided for compatibility with Ada
83 compilers that use the pragma for this purpose. You must provide at
least one of `External_Name' or `Link_Name'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Interrupt_Handler" origin="GNAT RM">
<DOC>Syntax:
pragma Interrupt_Handler (procedure_LOCAL_NAME);
This program unit pragma is supported for parameterless protected
procedures as described in Annex C of the Ada Reference Manual. On the
AAMP target the pragma can also be specified for nonprotected
parameterless procedures that are declared at the library level (which
includes procedures declared at the top level of a library package). In
the case of AAMP, when this pragma is applied to a nonprotected
procedure, the instruction `IERET' is generated for returns from the
procedure, enabling maskable interrupts, in place of the normal return
instruction.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Interrupt_Priority" origin="Ada RM">
<DOC>Syntax:
pragma Interrupt_Priority;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Interrupt_State" origin="GNAT RM">
<DOC>Syntax:
pragma Interrupt_State
([Name =&gt;] value,
[State =&gt;] SYSTEM | RUNTIME | USER);
Normally certain interrupts are reserved to the implementation. Any
attempt to attach an interrupt causes Program_Error to be raised, as
described in RM C.3.2(22). A typical example is the `SIGINT' interrupt
used in many systems for an `Ctrl-C' interrupt. Normally this
interrupt is reserved to the implementation, so that `Ctrl-C' can be
used to interrupt execution. Additionally, signals such as `SIGSEGV',
`SIGABRT', `SIGFPE' and `SIGILL' are often mapped to specific Ada
exceptions, or used to implement run-time functions such as the `abort'
statement and stack overflow checking.
Pragma `Interrupt_State' provides a general mechanism for overriding
such uses of interrupts. It subsumes the functionality of pragma
`Unreserve_All_Interrupts'. Pragma `Interrupt_State' is not available
on Windows. On all other platforms than VxWorks, it applies to
signals; on VxWorks, it applies to vectored hardware interrupts and may
be used to mark interrupts required by the board support package as
reserved.
Interrupts can be in one of three states:
* System
The interrupt is reserved (no Ada handler can be installed), and
the Ada run-time may not install a handler. As a result you are
guaranteed standard system default action if this interrupt is
raised. This also allows installing a low level handler via C APIs
such as sigaction(), outside of Ada control.
* Runtime
The interrupt is reserved (no Ada handler can be installed). The
run time is allowed to install a handler for internal control
purposes, but is not required to do so.
* User
The interrupt is unreserved. The user may install an Ada handler
via Ada.Interrupts and pragma Interrupt_Handler or Attach_Handler
to provide some other action.
These states are the allowed values of the `State' parameter of the
pragma. The `Name' parameter is a value of the type
`Ada.Interrupts.Interrupt_ID'. Typically, it is a name declared in
`Ada.Interrupts.Names'.
This is a configuration pragma, and the binder will check that there
are no inconsistencies between different units in a partition in how a
given interrupt is specified. It may appear anywhere a pragma is legal.
The effect is to move the interrupt to the specified state.
By declaring interrupts to be SYSTEM, you guarantee the standard system
action, such as a core dump.
By declaring interrupts to be USER, you guarantee that you can install
a handler.
Note that certain signals on many operating systems cannot be caught and
handled by applications. In such cases, the pragma is ignored. See the
operating system documentation, or the value of the array `Reserved'
declared in the spec of package `System.OS_Interface'.
Overriding the default state of signals used by the Ada runtime may
interfere with an application's runtime behavior in the cases of the
synchronous signals, and in the case of the signal used to implement
the `abort' statement.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Invariant" origin="GNAT RM">
<DOC>Syntax:
pragma Invariant
([Entity =&gt;] private_type_LOCAL_NAME,
[Check =&gt;] EXPRESSION
[,[Message =&gt;] String_Expression]);
This pragma provides exactly the same capabilities as the
Type_Invariant aspect defined in AI05-0146-1, and in the Ada 2012
Reference Manual. The Type_Invariant aspect is fully implemented in Ada
2012 mode, but since it requires the use of the aspect syntax, which is
not available except in 2012 mode, it is not possible to use the
Type_Invariant aspect in earlier versions of Ada. However the Invariant
pragma may be used in any version of Ada. Also note that the aspect
Invariant is a synonym in GNAT for the aspect Type_Invariant, but there
is no pragma Type_Invariant.
The pragma must appear within the visible part of the package
specification, after the type to which its Entity argument appears. As
with the Invariant aspect, the Check expression is not analyzed until
the end of the visible part of the package, so it may contain forward
references. The Message argument, if present, provides the exception
message used if the invariant is violated. If no Message parameter is
provided, a default message that identifies the line on which the
pragma appears is used.
It is permissible to have multiple Invariants for the same type entity,
in which case they are and'ed together. It is permissible to use this
pragma in Ada 2012 mode, but you cannot have both an invariant aspect
and an invariant pragma for the same entity.
For further details on the use of this pragma, see the Ada 2012
documentation of the Type_Invariant aspect.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Keep_Names" origin="GNAT RM">
<DOC>Syntax:
pragma Keep_Names ([On =&gt;] enumeration_first_subtype_LOCAL_NAME);
The `LOCAL_NAME' argument must refer to an enumeration first subtype in
the current declarative part. The effect is to retain the enumeration
literal names for use by `Image' and `Value' even if a global
`Discard_Names' pragma applies. This is useful when you want to
generally suppress enumeration literal names and for example you
therefore use a `Discard_Names' pragma in the `gnat.adc' file, but you
want to retain the names for specific enumeration types.</DOC>
</PRAGMA>
<PRAGMA id="0" name="License" origin="GNAT RM">
<DOC>Syntax:
pragma License (Unrestricted | GPL | Modified_GPL | Restricted);
This pragma is provided to allow automated checking for appropriate
license conditions with respect to the standard and modified GPL. A
pragma `License', which is a configuration pragma that typically
appears at the start of a source file or in a separate `gnat.adc' file,
specifies the licensing conditions of a unit as follows:
* Unrestricted This is used for a unit that can be freely used with
no license restrictions. Examples of such units are public domain
units, and units from the Ada Reference Manual.
* GPL This is used for a unit that is licensed under the unmodified
GPL, and which therefore cannot be `with'ed by a restricted unit.
* Modified_GPL This is used for a unit licensed under the GNAT
modified GPL that includes a special exception paragraph that
specifically permits the inclusion of the unit in programs without
requiring the entire program to be released under the GPL.
* Restricted This is used for a unit that is restricted in that it
is not permitted to depend on units that are licensed under the
GPL. Typical examples are proprietary code that is to be released
under more restrictive license conditions. Note that restricted
units are permitted to `with' units which are licensed under the
modified GPL (this is the whole point of the modified GPL).
Normally a unit with no `License' pragma is considered to have an
unknown license, and no checking is done. However, standard GNAT
headers are recognized, and license information is derived from them as
follows.
A GNAT license header starts with a line containing 78 hyphens. The
following comment text is searched for the appearance of any of the
following strings.
If the string 'GNU General Public License' is found, then the unit is
assumed to have GPL license, unless the string 'As a special exception'
follows, in which case the license is assumed to be modified GPL.
If one of the strings 'This specification is adapted from the Ada
Semantic Interface' or 'This specification is derived from the Ada
Reference Manual' is found then the unit is assumed to be unrestricted.
These default actions means that a program with a restricted license
pragma will automatically get warnings if a GPL unit is inappropriately
`with'ed. For example, the program:
with Sem_Ch3;
with GNAT.Sockets;
procedure Secret_Stuff is
end Secret_Stuff
if compiled with pragma `License' (`Restricted') in a `gnat.adc' file
will generate the warning:
with Sem_Ch3;
|
&gt;&gt;&gt; license of withed unit "Sem_Ch3" is incompatible
with GNAT.Sockets;
procedure Secret_Stuff is
Here we get a warning on `Sem_Ch3' since it is part of the GNAT
compiler and is licensed under the GPL, but no warning for
`GNAT.Sockets' which is part of the GNAT run time, and is therefore
licensed under the modified GPL.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Link_With" origin="GNAT RM">
<DOC>Syntax:
pragma Link_With (static_string_EXPRESSION {,static_string_EXPRESSION});
This pragma is provided for compatibility with certain Ada 83 compilers.
It has exactly the same effect as pragma `Linker_Options' except that
spaces occurring within one of the string expressions are treated as
separators. For example, in the following case:
pragma Link_With ("-labc -ldef");
results in passing the strings `-labc' and `-ldef' as two separate
arguments to the linker. In addition pragma Link_With allows multiple
arguments, with the same effect as successive pragmas.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Linker_Alias" origin="GNAT RM">
<DOC>Syntax:
pragma Linker_Alias (
[Entity =&gt;] LOCAL_NAME,
[Target =&gt;] static_string_EXPRESSION);
`LOCAL_NAME' must refer to an object that is declared at the library
level. This pragma establishes the given entity as a linker alias for
the given target. It is equivalent to `__attribute__((alias))' in GNU C
and causes `LOCAL_NAME' to be emitted as an alias for the symbol
`static_string_EXPRESSION' in the object file, that is to say no space
is reserved for `LOCAL_NAME' by the assembler and it will be resolved
to the same address as `static_string_EXPRESSION' by the linker.
The actual linker name for the target must be used (e.g., the fully
encoded name with qualification in Ada, or the mangled name in C++), or
it must be declared using the C convention with `pragma Import' or
`pragma Export'.
Not all target machines support this pragma. On some of them it is
accepted only if `pragma Weak_External' has been applied to
`LOCAL_NAME'.
-- Example of the use of pragma Linker_Alias
package p is
i : Integer := 1;
pragma Export (C, i);
new_name_for_i : Integer;
pragma Linker_Alias (new_name_for_i, "i");
end p;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Linker_Constructor" origin="GNAT RM">
<DOC>Syntax:
pragma Linker_Constructor (procedure_LOCAL_NAME);
`procedure_LOCAL_NAME' must refer to a parameterless procedure that is
declared at the library level. A procedure to which this pragma is
applied will be treated as an initialization routine by the linker. It
is equivalent to `__attribute__((constructor))' in GNU C and causes
`procedure_LOCAL_NAME' to be invoked before the entry point of the
executable is called (or immediately after the shared library is loaded
if the procedure is linked in a shared library), in particular before
the Ada run-time environment is set up.
Because of these specific contexts, the set of operations such a
procedure can perform is very limited and the type of objects it can
manipulate is essentially restricted to the elementary types. In
particular, it must only contain code to which pragma Restrictions
(No_Elaboration_Code) applies.
This pragma is used by GNAT to implement auto-initialization of shared
Stand Alone Libraries, which provides a related capability without the
restrictions listed above. Where possible, the use of Stand Alone
Libraries is preferable to the use of this pragma.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Linker_Destructor" origin="GNAT RM">
<DOC>Syntax:
pragma Linker_Destructor (procedure_LOCAL_NAME);
`procedure_LOCAL_NAME' must refer to a parameterless procedure that is
declared at the library level. A procedure to which this pragma is
applied will be treated as a finalization routine by the linker. It is
equivalent to `__attribute__((destructor))' in GNU C and causes
`procedure_LOCAL_NAME' to be invoked after the entry point of the
executable has exited (or immediately before the shared library is
unloaded if the procedure is linked in a shared library), in particular
after the Ada run-time environment is shut down.
See `pragma Linker_Constructor' for the set of restrictions that apply
because of these specific contexts.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Linker_Options" origin="Ada RM">
<DOC>Syntax:
pragma Linker_Options (string_expression);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Linker_Section" origin="GNAT RM">
<DOC>Syntax:
pragma Linker_Section (
[Entity =&gt;] LOCAL_NAME,
[Section =&gt;] static_string_EXPRESSION);
`LOCAL_NAME' must refer to an object, type, or subprogram that is
declared at the library level. This pragma specifies the name of the
linker section for the given entity. It is equivalent to
`__attribute__((section))' in GNU C and causes `LOCAL_NAME' to be
placed in the `static_string_EXPRESSION' section of the executable
(assuming the linker doesn't rename the section). GNAT also provides
an implementation defined aspect of the same name.
In the case of specifying this aspect for a type, the effect is to
specify the corresponding section for all library-level objects of the
type that do not have an explicit linker section set. Note that this
only applies to whole objects, not to components of composite objects.
In the case of a subprogram, the linker section applies to all
previously declared matching overloaded subprograms in the current
declarative part which do not already have a linker section assigned.
The linker section aspect is useful in this case for specifying
different linker sections for different elements of such an overloaded
set.
Note that an empty string specifies that no linker section is specified.
This is not quite the same as omitting the pragma or aspect, since it
can be used to specify that one element of an overloaded set of
subprograms has the default linker section, or that one object of a
type for which a linker section is specified should has the default
linker section.
The compiler normally places library-level entities in standard sections
depending on the class: procedures and functions generally go in the
`.text' section, initialized variables in the `.data' section and
uninitialized variables in the `.bss' section.
Other, special sections may exist on given target machines to map
special hardware, for example I/O ports or flash memory. This pragma is
a means to defer the final layout of the executable to the linker, thus
fully working at the symbolic level with the compiler.
Some file formats do not support arbitrary sections so not all target
machines support this pragma. The use of this pragma may cause a program
execution to be erroneous if it is used to place an entity into an
inappropriate section (e.g., a modified variable into the `.text'
section). See also `pragma Persistent_BSS'.
-- Example of the use of pragma Linker_Section
package IO_Card is
Port_A : Integer;
pragma Volatile (Port_A);
pragma Linker_Section (Port_A, ".bss.port_a");
Port_B : Integer;
pragma Volatile (Port_B);
pragma Linker_Section (Port_B, ".bss.port_b");
type Port_Type is new Integer with Linker_Section =&gt; ".bss";
PA : Port_Type with Linker_Section =&gt; ".bss.PA";
PB : Port_Type; -- ends up in linker section ".bss"
procedure Q with Linker_Section =&gt; "Qsection";
end IO_Card;</DOC>
</PRAGMA>
<PRAGMA id="0" name="List" origin="Ada RM">
<DOC>Syntax:
pragma List (identifier);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Lock_Free" origin="GNAT RM">
<DOC>Syntax: This pragma may be specified for protected types or objects. It
specifies that the implementation of protected operations must be
implemented without locks. Compilation fails if the compiler cannot
generate lock-free code for the operations.
The current conditions required to support this pragma are:
* Protected type declarations may not contain entries
* Protected subprogram declarations may not have nonelementary
parameters
In addition, each protected subprogram body must satisfy:
* May reference only one protected component
* May not reference nonconstant entities outside the protected
subprogram scope.
* May not contain address representation items, allocators, or
quantified expressions.
* May not contain delay, goto, loop, or procedure-call statements.
* May not contain exported and imported entities
* May not dereferenced access values
* Function calls and attribute references must be static</DOC>
</PRAGMA>
<PRAGMA id="0" name="Locking_Policy" origin="Ada RM">
<DOC>Syntax:
pragma Locking_Policy (policy_identifier);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Loop_Invariant" origin="GNAT RM">
<DOC>Syntax:
pragma Loop_Invariant ( boolean_EXPRESSION );
The effect of this pragma is similar to that of pragma `Assert', except
that in an `Assertion_Policy' pragma, the identifier `Loop_Invariant'
is used to control whether it is ignored or checked (or disabled).
`Loop_Invariant' can only appear as one of the items in the sequence of
statements of a loop body, or nested inside block statements that
appear in the sequence of statements of a loop body. The intention is
that it be used to represent a "loop invariant" assertion, i.e.
something that is true each time through the loop, and which can be
used to show that the loop is achieving its purpose.
Multiple `Loop_Invariant' and `Loop_Variant' pragmas that apply to the
same loop should be grouped in the same sequence of statements.
To aid in writing such invariants, the special attribute `Loop_Entry'
may be used to refer to the value of an expression on entry to the
loop. This attribute can only be used within the expression of a
`Loop_Invariant' pragma. For full details, see documentation of
attribute `Loop_Entry'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Loop_Optimize" origin="GNAT RM">
<DOC>Syntax:
pragma Loop_Optimize (OPTIMIZATION_HINT {, OPTIMIZATION_HINT});
OPTIMIZATION_HINT ::= Ivdep | No_Unroll | Unroll | No_Vector | Vector
This pragma must appear immediately within a loop statement. It allows
the programmer to specify optimization hints for the enclosing loop.
The hints are not mutually exclusive and can be freely mixed, but not
all combinations will yield a sensible outcome.
There are five supported optimization hints for a loop:
* Ivdep
The programmer asserts that there are no loop-carried dependencies
which would prevent consecutive iterations of the loop from being
executed simultaneously.
* No_Unroll
The loop must not be unrolled. This is a strong hint: the
compiler will not unroll a loop marked with this hint.
* Unroll
The loop should be unrolled. This is a weak hint: the compiler
will try to apply unrolling to this loop preferably to other
optimizations, notably vectorization, but there is no guarantee
that the loop will be unrolled.
* No_Vector
The loop must not be vectorized. This is a strong hint: the
compiler will not vectorize a loop marked with this hint.
* Vector
The loop should be vectorized. This is a weak hint: the compiler
will try to apply vectorization to this loop preferably to other
optimizations, notably unrolling, but there is no guarantee that
the loop will be vectorized.
These hints do not remove the need to pass the appropriate switches to
the compiler in order to enable the relevant optimizations, that is to
say `-funroll-loops' for unrolling and `-ftree-vectorize' for
vectorization.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Loop_Variant" origin="GNAT RM">
<DOC>Syntax:
pragma Loop_Variant ( LOOP_VARIANT_ITEM {, LOOP_VARIANT_ITEM } );
LOOP_VARIANT_ITEM ::= CHANGE_DIRECTION =&gt; discrete_EXPRESSION
CHANGE_DIRECTION ::= Increases | Decreases
`Loop_Variant' can only appear as one of the items in the sequence of
statements of a loop body, or nested inside block statements that
appear in the sequence of statements of a loop body. It allows the
specification of quantities which must always decrease or increase in
successive iterations of the loop. In its simplest form, just one
expression is specified, whose value must increase or decrease on each
iteration of the loop.
In a more complex form, multiple arguments can be given which are
intepreted in a nesting lexicographic manner. For example:
pragma Loop_Variant (Increases =&gt; X, Decreases =&gt; Y);
specifies that each time through the loop either X increases, or X stays
the same and Y decreases. A `Loop_Variant' pragma ensures that the loop
is making progress. It can be useful in helping to show informally or
prove formally that the loop always terminates.
`Loop_Variant' is an assertion whose effect can be controlled using an
`Assertion_Policy' with a check name of `Loop_Variant'. The policy can
be `Check' to enable the loop variant check, `Ignore' to ignore the
check (in which case the pragma has no effect on the program), or
`Disable' in which case the pragma is not even checked for correct
syntax.
Multiple `Loop_Invariant' and `Loop_Variant' pragmas that apply to the
same loop should be grouped in the same sequence of statements.
The `Loop_Entry' attribute may be used within the expressions of the
`Loop_Variant' pragma to refer to values on entry to the loop.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Machine_Attribute" origin="GNAT RM">
<DOC>Syntax:
pragma Machine_Attribute (
[Entity =&gt;] LOCAL_NAME,
[Attribute_Name =&gt;] static_string_EXPRESSION
[, [Info =&gt;] static_EXPRESSION {, static_EXPRESSION}] );
Machine-dependent attributes can be specified for types and/or
declarations. This pragma is semantically equivalent to
`__attribute__((`attribute_name'))' (if `info' is not specified) or
`__attribute__((`attribute_name(info')))' or
`__attribute__((`attribute_name(info,...')))' in GNU C, where
`attribute_name' is recognized by the compiler middle-end or the
`TARGET_ATTRIBUTE_TABLE' machine specific macro. Note that a string
literal for the optional parameter `info' or the following ones is
transformed by default into an identifier, which may make this pragma
unusable for some attributes. For further information see `GNU
Compiler Collection (GCC) Internals'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Main" origin="GNAT RM">
<DOC>Syntax:
pragma Main
(MAIN_OPTION [, MAIN_OPTION]);
MAIN_OPTION ::=
[Stack_Size =&gt;] static_integer_EXPRESSION
| [Task_Stack_Size_Default =&gt;] static_integer_EXPRESSION
| [Time_Slicing_Enabled =&gt;] static_boolean_EXPRESSION
This pragma is provided for compatibility with OpenVMS VAX Systems. It
has no effect in GNAT, other than being syntax checked.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Main_Storage" origin="GNAT RM">
<DOC>Syntax:
pragma Main_Storage
(MAIN_STORAGE_OPTION [, MAIN_STORAGE_OPTION]);
MAIN_STORAGE_OPTION ::=
[WORKING_STORAGE =&gt;] static_SIMPLE_EXPRESSION
| [TOP_GUARD =&gt;] static_SIMPLE_EXPRESSION
This pragma is provided for compatibility with OpenVMS VAX Systems. It
has no effect in GNAT, other than being syntax checked.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Max_Queue_Length" origin="GNAT RM">
<DOC>Syntax:
pragma Max_Entry_Queue (static_integer_EXPRESSION);
This pragma is used to specify the maximum callers per entry queue for
individual protected entries and entry families. It accepts a single
integer (-1 or more) as a parameter and must appear after the
declaration of an entry.
A value of -1 represents no additional restriction on queue length.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Body" origin="GNAT RM">
<DOC>Syntax:
pragma No_Body;
There are a number of cases in which a package spec does not require a
body, and in fact a body is not permitted. GNAT will not permit the
spec to be compiled if there is a body around. The pragma No_Body
allows you to provide a body file, even in a case where no body is
allowed. The body file must contain only comments and a single No_Body
pragma. This is recognized by the compiler as indicating that no body
is logically present.
This is particularly useful during maintenance when a package is
modified in such a way that a body needed before is no longer needed.
The provision of a dummy body with a No_Body pragma ensures that there
is no interference from earlier versions of the package body.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Caching" origin="GNAT RM">
<DOC>Syntax:
pragma No_Caching [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect `No_Caching'
in the SPARK 2014 Reference Manual, section 7.1.2.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Component_Reordering" origin="GNAT RM">
<DOC>Syntax:
pragma No_Component_Reordering [([Entity =&gt;] type_LOCAL_NAME)];
`type_LOCAL_NAME' must refer to a record type declaration in the current
declarative part. The effect is to preclude any reordering of components
for the layout of the record, i.e. the record is laid out by the
compiler in the order in which the components are declared textually.
The form with no argument is a configuration pragma which applies to
all record types declared in units to which the pragma applies and
there is a requirement that this pragma be used consistently within a
partition.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Elaboration_Code_All" origin="GNAT RM">
<DOC>Syntax:
pragma No_Elaboration_Code_All [(program_unit_NAME)];
This is a program unit pragma (there is also an equivalent aspect of the
same name) that establishes the restriction `No_Elaboration_Code' for
the current unit and any extended main source units (body and subunits).
It also has the effect of enforcing a transitive application of this
aspect, so that if any unit is implicitly or explicitly with'ed by the
current unit, it must also have the No_Elaboration_Code_All aspect set.
It may be applied to package or subprogram specs or their generic
versions.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Heap_Finalization" origin="GNAT RM">
<DOC>Syntax:
pragma No_Heap_Finalization [ (first_subtype_LOCAL_NAME) ];
Pragma `No_Heap_Finalization' may be used as a configuration pragma or
as a type-specific pragma.
In its configuration form, the pragma must appear within a
configuration file such as gnat.adc, without an argument. The pragma
suppresses the call to `Finalize' for heap-allocated objects created
through library-level named access-to-object types in cases where the
designated type requires finalization actions.
In its type-specific form, the argument of the pragma must denote a
library-level named access-to-object type. The pragma suppresses the
call to `Finalize' for heap-allocated objects created through the
specific access type in cases where the designated type requires
finalization actions.
It is still possible to finalize such heap-allocated objects by
explicitly deallocating them.
A library-level named access-to-object type declared within a generic
unit will lose its `No_Heap_Finalization' pragma when the corresponding
instance does not appear at the library level.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Inline" origin="GNAT RM">
<DOC>Syntax:
pragma No_Inline (NAME {, NAME});
This pragma suppresses inlining for the callable entity or the
instances of the generic subprogram designated by `NAME', including
inlining that results from the use of pragma `Inline'. This pragma is
always active, in particular it is not subject to the use of option
`-gnatn' or `-gnatN'. It is illegal to specify both pragma `No_Inline'
and pragma `Inline_Always' for the same `NAME'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Return" origin="GNAT RM">
<DOC>Syntax:
pragma No_Return (procedure_LOCAL_NAME {, procedure_LOCAL_NAME});
Each `procedure_LOCAL_NAME' argument must refer to one or more procedure
declarations in the current declarative part. A procedure to which this
pragma is applied may not contain any explicit `return' statements. In
addition, if the procedure contains any implicit returns from falling
off the end of a statement sequence, then execution of that implicit
return will cause Program_Error to be raised.
One use of this pragma is to identify procedures whose only purpose is
to raise an exception. Another use of this pragma is to suppress
incorrect warnings about missing returns in functions, where the last
statement of a function statement sequence is a call to such a
procedure.
Note that in Ada 2005 mode, this pragma is part of the language. It is
available in all earlier versions of Ada as an implementation-defined
pragma.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Strict_Aliasing" origin="GNAT RM">
<DOC>Syntax:
pragma No_Strict_Aliasing [([Entity =&gt;] type_LOCAL_NAME)];
`type_LOCAL_NAME' must refer to an access type declaration in the
current declarative part. The effect is to inhibit strict aliasing
optimization for the given type. The form with no arguments is a
configuration pragma which applies to all access types declared in
units to which the pragma applies. For a detailed description of the
strict aliasing optimization, and the situations in which it must be
suppressed, see the section on Optimization and Strict Aliasing in the
`GNAT User's Guide'.
This pragma currently has no effects on access to unconstrained array
types.</DOC>
</PRAGMA>
<PRAGMA id="0" name="No_Tagged_Streams" origin="GNAT RM">
<DOC>Syntax:
pragma No_Tagged_Streams [([Entity =&gt;] tagged_type_LOCAL_NAME)];
Normally when a tagged type is introduced using a full type declaration,
part of the processing includes generating stream access routines to be
used by stream attributes referencing the type (or one of its subtypes
or derived types). This can involve the generation of significant
amounts of code which is wasted space if stream routines are not needed
for the type in question.
The `No_Tagged_Streams' pragma causes the generation of these stream
routines to be skipped, and any attempt to use stream operations on
types subject to this pragma will be statically rejected as illegal.
There are two forms of the pragma. The form with no arguments must
appear in a declarative sequence or in the declarations of a package
spec. This pragma affects all subsequent root tagged types declared in
the declaration sequence, and specifies that no stream routines be
generated. The form with an argument (for which there is also a
corresponding aspect) specifies a single root tagged type for which
stream routines are not to be generated.
Once the pragma has been given for a particular root tagged type, all
subtypes and derived types of this type inherit the pragma
automatically, so the effect applies to a complete hierarchy (this is
necessary to deal with the class-wide dispatching versions of the
stream routines).
When pragmas `Discard_Names' and `No_Tagged_Streams' are simultaneously
applied to a tagged type its Expanded_Name and External_Tag are
initialized with empty strings. This is useful to avoid exposing entity
names at binary level but has a negative impact on the debuggability of
tagged types.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Normalize_Scalars" origin="GNAT RM">
<DOC>Syntax:
pragma Normalize_Scalars;
This is a language defined pragma which is fully implemented in GNAT.
The effect is to cause all scalar objects that are not otherwise
initialized to be initialized. The initial values are implementation
dependent and are as follows:
`Standard.Character'
Objects whose root type is Standard.Character are initialized to
Character'Last unless the subtype range excludes NUL (in which case
NUL is used). This choice will always generate an invalid value if
one exists.
`Standard.Wide_Character'
Objects whose root type is Standard.Wide_Character are initialized
to Wide_Character'Last unless the subtype range excludes NUL (in
which case NUL is used). This choice will always generate an
invalid value if one exists.
`Standard.Wide_Wide_Character'
Objects whose root type is Standard.Wide_Wide_Character are
initialized to the invalid value 16#FFFF_FFFF# unless the subtype
range excludes NUL (in which case NUL is used). This choice will
always generate an invalid value if one exists.
`Integer types'
Objects of an integer type are treated differently depending on
whether negative values are present in the subtype. If no negative
values are present, then all one bits is used as the initial value
except in the special case where zero is excluded from the
subtype, in which case all zero bits are used. This choice will
always generate an invalid value if one exists.
For subtypes with negative values present, the largest negative
number is used, except in the unusual case where this largest
negative number is in the subtype, and the largest positive number
is not, in which case the largest positive value is used. This
choice will always generate an invalid value if one exists.
`Floating-Point Types'
Objects of all floating-point types are initialized to all 1-bits.
For standard IEEE format, this corresponds to a NaN (not a number)
which is indeed an invalid value.
`Fixed-Point Types'
Objects of all fixed-point types are treated as described above
for integers, with the rules applying to the underlying integer
value used to represent the fixed-point value.
`Modular types'
Objects of a modular type are initialized to all one bits, except
in the special case where zero is excluded from the subtype, in
which case all zero bits are used. This choice will always
generate an invalid value if one exists.
`Enumeration types'
Objects of an enumeration type are initialized to all one-bits,
i.e., to the value `2 ** typ'Size - 1' unless the subtype excludes
the literal whose Pos value is zero, in which case a code of zero
is used. This choice will always generate an invalid value if one
exists.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Obsolescent" origin="GNAT RM">
<DOC>Syntax:
pragma Obsolescent;
pragma Obsolescent (
[Message =&gt;] static_string_EXPRESSION
[,[Version =&gt;] Ada_05]]);
pragma Obsolescent (
[Entity =&gt;] NAME
[,[Message =&gt;] static_string_EXPRESSION
[,[Version =&gt;] Ada_05]] );
This pragma can occur immediately following a declaration of an entity,
including the case of a record component. If no Entity argument is
present, then this declaration is the one to which the pragma applies.
If an Entity parameter is present, it must either match the name of the
entity in this declaration, or alternatively, the pragma can
immediately follow an enumeration type declaration, where the Entity
argument names one of the enumeration literals.
This pragma is used to indicate that the named entity is considered
obsolescent and should not be used. Typically this is used when an API
must be modified by eventually removing or modifying existing
subprograms or other entities. The pragma can be used at an
intermediate stage when the entity is still present, but will be
removed later.
The effect of this pragma is to output a warning message on a reference
to an entity thus marked that the subprogram is obsolescent if the
appropriate warning option in the compiler is activated. If the
`Message' parameter is present, then a second warning message is given
containing this text. In addition, a reference to the entity is
considered to be a violation of pragma `Restrictions
(No_Obsolescent_Features)'.
This pragma can also be used as a program unit pragma for a package, in
which case the entity name is the name of the package, and the pragma
indicates that the entire package is considered obsolescent. In this
case a client `with'ing such a package violates the restriction, and
the `with' clause is flagged with warnings if the warning option is set.
If the `Version' parameter is present (which must be exactly the
identifier `Ada_05', no other argument is allowed), then the indication
of obsolescence applies only when compiling in Ada 2005 mode. This is
primarily intended for dealing with the situations in the predefined
library where subprograms or packages have become defined as
obsolescent in Ada 2005 (e.g., in `Ada.Characters.Handling'), but may
be used anywhere.
The following examples show typical uses of this pragma:
package p is
pragma Obsolescent (p, Message =&gt; "use pp instead of p");
end p;
package q is
procedure q2;
pragma Obsolescent ("use q2new instead");
type R is new integer;
pragma Obsolescent
(Entity =&gt; R,
Message =&gt; "use RR in Ada 2005",
Version =&gt; Ada_05);
type M is record
F1 : Integer;
F2 : Integer;
pragma Obsolescent;
F3 : Integer;
end record;
type E is (a, bc, 'd', quack);
pragma Obsolescent (Entity =&gt; bc)
pragma Obsolescent (Entity =&gt; 'd')
function "+"
(a, b : character) return character;
pragma Obsolescent (Entity =&gt; "+");
end;
Note that, as for all pragmas, if you use a pragma argument identifier,
then all subsequent parameters must also use a pragma argument
identifier. So if you specify `Entity =&gt;' for the `Entity' argument,
and a `Message' argument is present, it must be preceded by `Message
=&gt;'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Optimize" origin="Ada RM">
<DOC>Syntax:
pragma Optimize (identifier);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Optimize_Alignment" origin="GNAT RM">
<DOC>Syntax:
pragma Optimize_Alignment (TIME | SPACE | OFF);
This is a configuration pragma which affects the choice of default
alignments for types and objects where no alignment is explicitly
specified. There is a time/space trade-off in the selection of these
values. Large alignments result in more efficient code, at the expense
of larger data space, since sizes have to be increased to match these
alignments. Smaller alignments save space, but the access code is
slower. The normal choice of default alignments for types and
individual alignment promotions for objects (which is what you get if
you do not use this pragma, or if you use an argument of OFF), tries to
balance these two requirements.
Specifying SPACE causes smaller default alignments to be chosen in two
cases. First any packed record is given an alignment of 1. Second, if
a size is given for the type, then the alignment is chosen to avoid
increasing this size. For example, consider:
type R is record
X : Integer;
Y : Character;
end record;
for R'Size use 5*8;
In the default mode, this type gets an alignment of 4, so that access
to the Integer field X are efficient. But this means that objects of
the type end up with a size of 8 bytes. This is a valid choice, since
sizes of objects are allowed to be bigger than the size of the type,
but it can waste space if for example fields of type R appear in an
enclosing record. If the above type is compiled in `Optimize_Alignment
(Space)' mode, the alignment is set to 1.
However, there is one case in which SPACE is ignored. If a variable
length record (that is a discriminated record with a component which is
an array whose length depends on a discriminant), has a pragma Pack,
then it is not in general possible to set the alignment of such a
record to one, so the pragma is ignored in this case (with a warning).
Specifying SPACE also disables alignment promotions for standalone
objects, which occur when the compiler increases the alignment of a
specific object without changing the alignment of its type.
Specifying SPACE also disables component reordering in unpacked record
types, which can result in larger sizes in order to meet alignment
requirements.
Specifying TIME causes larger default alignments to be chosen in the
case of small types with sizes that are not a power of 2. For example,
consider:
type R is record
A : Character;
B : Character;
C : Boolean;
end record;
pragma Pack (R);
for R'Size use 17;
The default alignment for this record is normally 1, but if this type is
compiled in `Optimize_Alignment (Time)' mode, then the alignment is set
to 4, which wastes space for objects of the type, since they are now 4
bytes long, but results in more efficient access when the whole record
is referenced.
As noted above, this is a configuration pragma, and there is a
requirement that all units in a partition be compiled with a consistent
setting of the optimization setting. This would normally be achieved by
use of a configuration pragma file containing the appropriate setting.
The exception to this rule is that units with an explicit configuration
pragma in the same file as the source unit are excluded from the
consistency check, as are all predefined units. The latter are compiled
by default in pragma Optimize_Alignment (Off) mode if no pragma appears
at the start of the file.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ordered" origin="GNAT RM">
<DOC>Syntax:
pragma Ordered (enumeration_first_subtype_LOCAL_NAME);
Most enumeration types are from a conceptual point of view unordered.
For example, consider:
type Color is (Red, Blue, Green, Yellow);
By Ada semantics `Blue &gt; Red' and `Green &gt; Blue', but really these
relations make no sense; the enumeration type merely specifies a set of
possible colors, and the order is unimportant.
For unordered enumeration types, it is generally a good idea if clients
avoid comparisons (other than equality or inequality) and explicit
ranges. (A `client' is a unit where the type is referenced, other than
the unit where the type is declared, its body, and its subunits.) For
example, if code buried in some client says:
if Current_Color &lt; Yellow then ...
if Current_Color in Blue .. Green then ...
then the client code is relying on the order, which is undesirable. It
makes the code hard to read and creates maintenance difficulties if
entries have to be added to the enumeration type. Instead, the code in
the client should list the possibilities, or an appropriate subtype
should be declared in the unit that declares the original enumeration
type. E.g., the following subtype could be declared along with the type
`Color':
subtype RBG is Color range Red .. Green;
and then the client could write:
if Current_Color in RBG then ...
if Current_Color = Blue or Current_Color = Green then ...
However, some enumeration types are legitimately ordered from a
conceptual point of view. For example, if you declare:
type Day is (Mon, Tue, Wed, Thu, Fri, Sat, Sun);
then the ordering imposed by the language is reasonable, and clients
can depend on it, writing for example:
if D in Mon .. Fri then ...
if D &lt; Wed then ...
The pragma `Ordered' is provided to mark enumeration types that are
conceptually ordered, alerting the reader that clients may depend on
the ordering. GNAT provides a pragma to mark enumerations as ordered
rather than one to mark them as unordered, since in our experience, the
great majority of enumeration types are conceptually unordered.
The types `Boolean', `Character', `Wide_Character', and
`Wide_Wide_Character' are considered to be ordered types, so each is
declared with a pragma `Ordered' in package `Standard'.
Normally pragma `Ordered' serves only as documentation and a guide for
coding standards, but GNAT provides a warning switch `-gnatw.u' that
requests warnings for inappropriate uses (comparisons and explicit
subranges) for unordered types. If this switch is used, then any
enumeration type not marked with pragma `Ordered' will be considered as
unordered, and will generate warnings for inappropriate uses.
Note that generic types are not considered ordered or unordered (since
the template can be instantiated for both cases), so we never generate
warnings for the case of generic enumerated types.
For additional information please refer to the description of the
`-gnatw.u' switch in the GNAT User's Guide.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Overflow_Mode" origin="GNAT RM">
<DOC>Syntax:
pragma Overflow_Mode
( [General =&gt;] MODE
[,[Assertions =&gt;] MODE]);
MODE ::= STRICT | MINIMIZED | ELIMINATED
This pragma sets the current overflow mode to the given setting. For
details of the meaning of these modes, please refer to the 'Overflow
Check Handling in GNAT' appendix in the GNAT User's Guide. If only the
`General' parameter is present, the given mode applies to all
expressions. If both parameters are present, the `General' mode applies
to expressions outside assertions, and the `Eliminated' mode applies to
expressions within assertions.
The case of the `MODE' parameter is ignored, so `MINIMIZED',
`Minimized' and `minimized' all have the same effect.
The `Overflow_Mode' pragma has the same scoping and placement rules as
pragma `Suppress', so it can occur either as a configuration pragma,
specifying a default for the whole program, or in a declarative scope,
where it applies to the remaining declarations and statements in that
scope.
The pragma `Suppress (Overflow_Check)' suppresses overflow checking,
but does not affect the overflow mode.
The pragma `Unsuppress (Overflow_Check)' unsuppresses (enables)
overflow checking, but does not affect the overflow mode.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Overriding_Renamings" origin="GNAT RM">
<DOC>Syntax:
pragma Overriding_Renamings;
This is a GNAT configuration pragma to simplify porting legacy code
accepted by the Rational Ada compiler. In the presence of this pragma,
a renaming declaration that renames an inherited operation declared in
the same scope is legal if selected notation is used as in:
pragma Overriding_Renamings;
package R is
function F (..);
function F (..) renames R.F;
end R;
even though RM 8.3 (15) stipulates that an overridden operation is not
visible within the declaration of the overriding operation.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Pack" origin="Ada RM">
<DOC>Syntax:
pragma Pack;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Page" origin="Ada RM">
<DOC>Syntax:
pragma Page;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Part_Of" origin="GNAT RM">
<DOC>Syntax:
pragma Part_Of (ABSTRACT_STATE);
ABSTRACT_STATE ::= NAME
For the semantics of this pragma, see the entry for aspect `Part_Of' in
the SPARK 2014 Reference Manual, section 7.2.6.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Partition_Elaboration_Policy" origin="GNAT RM">
<DOC>Syntax:
pragma Partition_Elaboration_Policy (POLICY_IDENTIFIER);
POLICY_IDENTIFIER ::= Concurrent | Sequential
This pragma is standard in Ada 2005, but is available in all earlier
versions of Ada as an implementation-defined pragma. See Ada 2012
Reference Manual for details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Passive" origin="GNAT RM">
<DOC>Syntax:
pragma Passive [(Semaphore | No)];
Syntax checked, but otherwise ignored by GNAT. This is recognized for
compatibility with DEC Ada 83 implementations, where it is used within a
task definition to request that a task be made passive. If the argument
`Semaphore' is present, or the argument is omitted, then DEC Ada 83
treats the pragma as an assertion that the containing task is passive
and that optimization of context switch with this task is permitted and
desired. If the argument `No' is present, the task must not be
optimized. GNAT does not attempt to optimize any tasks in this manner
(since protected objects are available in place of passive tasks).
For more information on the subject of passive tasks, see the section
'Passive Task Optimization' in the GNAT Users Guide.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Persistent_BSS" origin="GNAT RM">
<DOC>Syntax:
pragma Persistent_BSS [(LOCAL_NAME)]
This pragma allows selected objects to be placed in the
`.persistent_bss' section. On some targets the linker and loader
provide for special treatment of this section, allowing a program to be
reloaded without affecting the contents of this data (hence the name
persistent).
There are two forms of usage. If an argument is given, it must be the
local name of a library-level object, with no explicit initialization
and whose type is potentially persistent. If no argument is given, then
the pragma is a configuration pragma, and applies to all library-level
objects with no explicit initialization of potentially persistent types.
A potentially persistent type is a scalar type, or an untagged,
non-discriminated record, all of whose components have no explicit
initialization and are themselves of a potentially persistent type, or
an array, all of whose constraints are static, and whose component type
is potentially persistent.
If this pragma is used on a target where this feature is not supported,
then the pragma will be ignored. See also `pragma Linker_Section'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Post" origin="GNAT RM">
<DOC>Syntax:
pragma Post (Boolean_Expression);
The `Post' pragma is intended to be an exact replacement for the
language-defined `Post' aspect, and shares its restrictions and
semantics. It must appear either immediately following the
corresponding subprogram declaration (only other pragmas may
intervene), or if there is no separate subprogram declaration, then it
can appear at the start of the declarations in a subprogram body
(preceded only by other pragmas).</DOC>
</PRAGMA>
<PRAGMA id="0" name="Post_Class" origin="GNAT RM">
<DOC>Syntax:
pragma Post_Class (Boolean_Expression);
The `Post_Class' pragma is intended to be an exact replacement for the
language-defined `Post'Class' aspect, and shares its restrictions and
semantics. It must appear either immediately following the
corresponding subprogram declaration (only other pragmas may
intervene), or if there is no separate subprogram declaration, then it
can appear at the start of the declarations in a subprogram body
(preceded only by other pragmas).
Note: This pragma is called `Post_Class' rather than `Post'Class'
because the latter would not be strictly conforming to the allowed
syntax for pragmas. The motivation for provinding pragmas equivalent to
the aspects is to allow a program to be written using the pragmas, and
then compiled if necessary using an Ada compiler that does not
recognize the pragmas or aspects, but is prepared to ignore the
pragmas. The assertion policy that controls this pragma is
`Post'Class', not `Post_Class'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Postcondition" origin="GNAT RM">
<DOC>Syntax:
pragma Postcondition (
[Check =&gt;] Boolean_Expression
[,[Message =&gt;] String_Expression]);
The `Postcondition' pragma allows specification of automatic
postcondition checks for subprograms. These checks are similar to
assertions, but are automatically inserted just prior to the return
statements of the subprogram with which they are associated (including
implicit returns at the end of procedure bodies and associated
exception handlers).
In addition, the boolean expression which is the condition which must
be true may contain references to function'Result in the case of a
function to refer to the returned value.
`Postcondition' pragmas may appear either immediately following the
(separate) declaration of a subprogram, or at the start of the
declarations of a subprogram body. Only other pragmas may intervene
(that is appear between the subprogram declaration and its
postconditions, or appear before the postcondition in the declaration
sequence in a subprogram body). In the case of a postcondition
appearing after a subprogram declaration, the formal arguments of the
subprogram are visible, and can be referenced in the postcondition
expressions.
The postconditions are collected and automatically tested just before
any return (implicit or explicit) in the subprogram body. A
postcondition is only recognized if postconditions are active at the
time the pragma is encountered. The compiler switch `gnata' turns on
all postconditions by default, and pragma `Check_Policy' with an
identifier of `Postcondition' can also be used to control whether
postconditions are active.
The general approach is that postconditions are placed in the spec if
they represent functional aspects which make sense to the client. For
example we might have:
function Direction return Integer;
pragma Postcondition
(Direction'Result = +1
or else
Direction'Result = -1);
which serves to document that the result must be +1 or -1, and will
test that this is the case at run time if postcondition checking is
active.
Postconditions within the subprogram body can be used to check that
some internal aspect of the implementation, not visible to the client,
is operating as expected. For instance if a square root routine keeps
an internal counter of the number of times it is called, then we might
have the following postcondition:
Sqrt_Calls : Natural := 0;
function Sqrt (Arg : Float) return Float is
pragma Postcondition
(Sqrt_Calls = Sqrt_Calls'Old + 1);
end Sqrt
As this example, shows, the use of the `Old' attribute is often useful
in postconditions to refer to the state on entry to the subprogram.
Note that postconditions are only checked on normal returns from the
subprogram. If an abnormal return results from raising an exception,
then the postconditions are not checked.
If a postcondition fails, then the exception
`System.Assertions.Assert_Failure' is raised. If a message argument was
supplied, then the given string will be used as the exception message.
If no message argument was supplied, then the default message has the
form "Postcondition failed at file_name:line". The exception is raised
in the context of the subprogram body, so it is possible to catch
postcondition failures within the subprogram body itself.
Within a package spec, normal visibility rules in Ada would prevent
forward references within a postcondition pragma to functions defined
later in the same package. This would introduce undesirable ordering
constraints. To avoid this problem, all postcondition pragmas are
analyzed at the end of the package spec, allowing forward references.
The following example shows that this even allows mutually recursive
postconditions as in:
package Parity_Functions is
function Odd (X : Natural) return Boolean;
pragma Postcondition
(Odd'Result =
(x = 1
or else
(x /= 0 and then Even (X - 1))));
function Even (X : Natural) return Boolean;
pragma Postcondition
(Even'Result =
(x = 0
or else
(x /= 1 and then Odd (X - 1))));
end Parity_Functions;
There are no restrictions on the complexity or form of conditions used
within `Postcondition' pragmas. The following example shows that it is
even possible to verify performance behavior.
package Sort is
Performance : constant Float;
-- Performance constant set by implementation
-- to match target architecture behavior.
procedure Treesort (Arg : String);
-- Sorts characters of argument using N*logN sort
pragma Postcondition
(Float (Clock - Clock'Old) &lt;=
Float (Arg'Length) *
log (Float (Arg'Length)) *
Performance);
end Sort;
Note: postcondition pragmas associated with subprograms that are marked
as Inline_Always, or those marked as Inline with front-end inlining
(-gnatN option set) are accepted and legality-checked by the compiler,
but are ignored at run-time even if postcondition checking is enabled.
Note that pragma `Postcondition' differs from the language-defined
`Post' aspect (and corresponding `Post' pragma) in allowing multiple
occurrences, allowing occurences in the body even if there is a
separate spec, and allowing a second string parameter, and the use of
the pragma identifier `Check'. Historically, pragma `Postcondition' was
implemented prior to the development of Ada 2012, and has been retained
in its original form for compatibility purposes.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Pre" origin="GNAT RM">
<DOC>Syntax:
pragma Pre (Boolean_Expression);
The `Pre' pragma is intended to be an exact replacement for the
language-defined `Pre' aspect, and shares its restrictions and
semantics. It must appear either immediately following the
corresponding subprogram declaration (only other pragmas may
intervene), or if there is no separate subprogram declaration, then it
can appear at the start of the declarations in a subprogram body
(preceded only by other pragmas).</DOC>
</PRAGMA>
<PRAGMA id="0" name="Pre_Class" origin="GNAT RM">
<DOC>Syntax:
pragma Pre_Class (Boolean_Expression);
The `Pre_Class' pragma is intended to be an exact replacement for the
language-defined `Pre'Class' aspect, and shares its restrictions and
semantics. It must appear either immediately following the
corresponding subprogram declaration (only other pragmas may
intervene), or if there is no separate subprogram declaration, then it
can appear at the start of the declarations in a subprogram body
(preceded only by other pragmas).
Note: This pragma is called `Pre_Class' rather than `Pre'Class' because
the latter would not be strictly conforming to the allowed syntax for
pragmas. The motivation for providing pragmas equivalent to the aspects
is to allow a program to be written using the pragmas, and then
compiled if necessary using an Ada compiler that does not recognize the
pragmas or aspects, but is prepared to ignore the pragmas. The assertion
policy that controls this pragma is `Pre'Class', not `Pre_Class'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Precondition" origin="GNAT RM">
<DOC>Syntax:
pragma Precondition (
[Check =&gt;] Boolean_Expression
[,[Message =&gt;] String_Expression]);
The `Precondition' pragma is similar to `Postcondition' except that the
corresponding checks take place immediately upon entry to the
subprogram, and if a precondition fails, the exception is raised in the
context of the caller, and the attribute 'Result cannot be used within
the precondition expression.
Otherwise, the placement and visibility rules are identical to those
described for postconditions. The following is an example of use within
a package spec:
package Math_Functions is
function Sqrt (Arg : Float) return Float;
pragma Precondition (Arg &gt;= 0.0)
end Math_Functions;
`Precondition' pragmas may appear either immediately following the
(separate) declaration of a subprogram, or at the start of the
declarations of a subprogram body. Only other pragmas may intervene
(that is appear between the subprogram declaration and its
postconditions, or appear before the postcondition in the declaration
sequence in a subprogram body).
Note: precondition pragmas associated with subprograms that are marked
as Inline_Always, or those marked as Inline with front-end inlining
(-gnatN option set) are accepted and legality-checked by the compiler,
but are ignored at run-time even if precondition checking is enabled.
Note that pragma `Precondition' differs from the language-defined `Pre'
aspect (and corresponding `Pre' pragma) in allowing multiple
occurrences, allowing occurences in the body even if there is a
separate spec, and allowing a second string parameter, and the use of
the pragma identifier `Check'. Historically, pragma `Precondition' was
implemented prior to the development of Ada 2012, and has been retained
in its original form for compatibility purposes.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Predicate" origin="GNAT RM">
<DOC>Syntax:
pragma Predicate
([Entity =&gt;] type_LOCAL_NAME,
[Check =&gt;] EXPRESSION);
This pragma (available in all versions of Ada in GNAT) encompasses both
the `Static_Predicate' and `Dynamic_Predicate' aspects in Ada 2012. A
predicate is regarded as static if it has an allowed form for
`Static_Predicate' and is otherwise treated as a `Dynamic_Predicate'.
Otherwise, predicates specified by this pragma behave exactly as
described in the Ada 2012 reference manual. For example, if we have
type R is range 1 .. 10;
subtype S is R;
pragma Predicate (Entity =&gt; S, Check =&gt; S not in 4 .. 6);
subtype Q is R
pragma Predicate (Entity =&gt; Q, Check =&gt; F(Q) or G(Q));
the effect is identical to the following Ada 2012 code:
type R is range 1 .. 10;
subtype S is R with
Static_Predicate =&gt; S not in 4 .. 6;
subtype Q is R with
Dynamic_Predicate =&gt; F(Q) or G(Q);
Note that there are no pragmas `Dynamic_Predicate' or
`Static_Predicate'. That is because these pragmas would affect legality
and semantics of the program and thus do not have a neutral effect if
ignored. The motivation behind providing pragmas equivalent to
corresponding aspects is to allow a program to be written using the
pragmas, and then compiled with a compiler that will ignore the
pragmas. That doesn't work in the case of static and dynamic
predicates, since if the corresponding pragmas are ignored, then the
behavior of the program is fundamentally changed (for example a
membership test `A in B' would not take into account a predicate
defined for subtype B). When following this approach, the use of
predicates should be avoided.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Predicate_Failure" origin="GNAT RM">
<DOC>Syntax:
pragma Predicate_Failure
([Entity =&gt;] type_LOCAL_NAME,
[Message =&gt;] String_Expression);
The `Predicate_Failure' pragma is intended to be an exact replacement
for the language-defined `Predicate_Failure' aspect, and shares its
restrictions and semantics.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Preelaborable_Initialization" origin="GNAT RM">
<DOC>Syntax:
pragma Preelaborable_Initialization (DIRECT_NAME);
This pragma is standard in Ada 2005, but is available in all earlier
versions of Ada as an implementation-defined pragma. See Ada 2012
Reference Manual for details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Preelaborate" origin="Ada RM">
<DOC>Syntax:
pragma Preelaborate [(library_unit_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Prefix_Exception_Messages" origin="GNAT RM">
<DOC>Syntax:
pragma Prefix_Exception_Messages;
This is an implementation-defined configuration pragma that affects the
behavior of raise statements with a message given as a static string
constant (typically a string literal). In such cases, the string will
be automatically prefixed by the name of the enclosing entity (giving
the package and subprogram containing the raise statement). This helps
to identify where messages are coming from, and this mode is automatic
for the run-time library.
The pragma has no effect if the message is computed with an expression
other than a static string constant, since the assumption in this case
is that the program computes exactly the string it wants. If you still
want the prefixing in this case, you can always call
`GNAT.Source_Info.Enclosing_Entity' and prepend the string manually.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Priority" origin="Ada RM">
<DOC>Syntax:
pragma Priority;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Priority_Specific_Dispatching" origin="GNAT RM">
<DOC>Syntax:
pragma Priority_Specific_Dispatching (
POLICY_IDENTIFIER,
first_priority_EXPRESSION,
last_priority_EXPRESSION)
POLICY_IDENTIFIER ::=
EDF_Across_Priorities |
FIFO_Within_Priorities |
Non_Preemptive_Within_Priorities |
Round_Robin_Within_Priorities
This pragma is standard in Ada 2005, but is available in all earlier
versions of Ada as an implementation-defined pragma. See Ada 2012
Reference Manual for details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Profile" origin="GNAT RM">
<DOC>Syntax:
pragma Profile (Ravenscar | Restricted | Rational |
GNAT_Extended_Ravenscar | GNAT_Ravenscar_EDF );
This pragma is standard in Ada 2005, but is available in all earlier
versions of Ada as an implementation-defined pragma. This is a
configuration pragma that establishes a set of configuration pragmas
that depend on the argument. `Ravenscar' is standard in Ada 2005. The
other possibilities (`Restricted', `Rational',
`GNAT_Extended_Ravenscar', `GNAT_Ravenscar_EDF') are
implementation-defined. The set of configuration pragmas is defined in
the following sections.
* Pragma Profile (Ravenscar)
The `Ravenscar' profile is standard in Ada 2005, but is available
in all earlier versions of Ada as an implementation-defined
pragma. This profile establishes the following set of
configuration pragmas:
* `Task_Dispatching_Policy (FIFO_Within_Priorities)'
[RM D.2.2] Tasks are dispatched following a preemptive
priority-ordered scheduling policy.
* `Locking_Policy (Ceiling_Locking)'
[RM D.3] While tasks and interrupts execute a protected
action, they inherit the ceiling priority of the
corresponding protected object.
* `Detect_Blocking'
This pragma forces the detection of potentially blocking
operations within a protected operation, and to raise
Program_Error if that happens.
plus the following set of restrictions:
* `Max_Entry_Queue_Length =&gt; 1'
No task can be queued on a protected entry.
* `Max_Protected_Entries =&gt; 1'
* `Max_Task_Entries =&gt; 0'
No rendezvous statements are allowed.
* `No_Abort_Statements'
* `No_Dynamic_Attachment'
* `No_Dynamic_Priorities'
* `No_Implicit_Heap_Allocations'
* `No_Local_Protected_Objects'
* `No_Local_Timing_Events'
* `No_Protected_Type_Allocators'
* `No_Relative_Delay'
* `No_Requeue_Statements'
* `No_Select_Statements'
* `No_Specific_Termination_Handlers'
* `No_Task_Allocators'
* `No_Task_Hierarchy'
* `No_Task_Termination'
* `Simple_Barriers'
The Ravenscar profile also includes the following restrictions
that specify that there are no semantic dependences on the
corresponding predefined packages:
* `No_Dependence =&gt; Ada.Asynchronous_Task_Control'
* `No_Dependence =&gt; Ada.Calendar'
* `No_Dependence =&gt; Ada.Execution_Time.Group_Budget'
* `No_Dependence =&gt; Ada.Execution_Time.Timers'
* `No_Dependence =&gt; Ada.Task_Attributes'
* `No_Dependence =&gt; System.Multiprocessors.Dispatching_Domains'
This set of configuration pragmas and restrictions correspond to
the definition of the 'Ravenscar Profile' for limited tasking,
devised and published by the `International Real-Time Ada
Workshop, 1997'. A description is also available at
&lt;http://www-users.cs.york.ac.uk/~burns/ravenscar.ps&gt;.
The original definition of the profile was revised at subsequent
IRTAW meetings. It has been included in the ISO `Guide for the Use
of the Ada Programming Language in High Integrity Systems', and
was made part of the Ada 2005 standard. The formal definition
given by the Ada Rapporteur Group (ARG) can be found in two Ada
Issues (AI-249 and AI-305) available at
&lt;http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ais/ai-00249.txt&gt; and
&lt;http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ais/ai-00305.txt&gt;.
The above set is a superset of the restrictions provided by pragma
`Profile (Restricted)', it includes six additional restrictions
(`Simple_Barriers', `No_Select_Statements', `No_Calendar',
`No_Implicit_Heap_Allocations', `No_Relative_Delay' and
`No_Task_Termination'). This means that pragma `Profile
(Ravenscar)', like the pragma `Profile (Restricted)',
automatically causes the use of a simplified, more efficient
version of the tasking run-time library.
* Pragma Profile (GNAT_Extended_Ravenscar)
This profile corresponds to a GNAT specific extension of the
Ravenscar profile. The profile may change in the future although
only in a compatible way: some restrictions may be removed or
relaxed. It is defined as a variation of the Ravenscar profile.
The `No_Implicit_Heap_Allocations' restriction has been replaced
by `No_Implicit_Task_Allocations' and
`No_Implicit_Protected_Object_Allocations'.
The `Simple_Barriers' restriction has been replaced by
`Pure_Barriers'.
The `Max_Protected_Entries', `Max_Entry_Queue_Length', and
`No_Relative_Delay' restrictions have been removed.
* Pragma Profile (GNAT_Ravenscar_EDF)
This profile corresponds to the Ravenscar profile but using
EDF_Across_Priority as the Task_Scheduling_Policy.
* Pragma Profile (Restricted)
This profile corresponds to the GNAT restricted run time. It
establishes the following set of restrictions:
* `No_Abort_Statements'
* `No_Entry_Queue'
* `No_Task_Hierarchy'
* `No_Task_Allocators'
* `No_Dynamic_Priorities'
* `No_Terminate_Alternatives'
* `No_Dynamic_Attachment'
* `No_Protected_Type_Allocators'
* `No_Local_Protected_Objects'
* `No_Requeue_Statements'
* `No_Task_Attributes_Package'
* `Max_Asynchronous_Select_Nesting = 0'
* `Max_Task_Entries = 0'
* `Max_Protected_Entries = 1'
* `Max_Select_Alternatives = 0'
This set of restrictions causes the automatic selection of a
simplified version of the run time that provides improved
performance for the limited set of tasking functionality permitted
by this set of restrictions.
* Pragma Profile (Rational)
The Rational profile is intended to facilitate porting legacy code
that compiles with the Rational APEX compiler, even when the code
includes non- conforming Ada constructs. The profile enables the
following three pragmas:
* `pragma Implicit_Packing'
* `pragma Overriding_Renamings'
* `pragma Use_VADS_Size'</DOC>
</PRAGMA>
<PRAGMA id="0" name="Profile_Warnings" origin="GNAT RM">
<DOC>Syntax:
pragma Profile_Warnings (Ravenscar | Restricted | Rational);
This is an implementation-defined pragma that is similar in effect to
`pragma Profile' except that instead of generating `Restrictions'
pragmas, it generates `Restriction_Warnings' pragmas. The result is that
violations of the profile generate warning messages instead of error
messages.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Propagate_Exceptions" origin="GNAT RM">
<DOC>Syntax:
pragma Propagate_Exceptions;
This pragma is now obsolete and, other than generating a warning if
warnings on obsolescent features are enabled, is ignored. It is
retained for compatibility purposes. It used to be used in connection
with optimization of a now-obsolete mechanism for implementation of
exceptions.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Provide_Shift_Operators" origin="GNAT RM">
<DOC>Syntax:
pragma Provide_Shift_Operators (integer_first_subtype_LOCAL_NAME);
This pragma can be applied to a first subtype local name that specifies
either an unsigned or signed type. It has the effect of providing the
five shift operators (Shift_Left, Shift_Right, Shift_Right_Arithmetic,
Rotate_Left and Rotate_Right) for the given type. It is similar to
including the function declarations for these five operators, together
with the pragma Import (Intrinsic, ...) statements.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Psect_Object" origin="GNAT RM">
<DOC>Syntax:
pragma Psect_Object (
[Internal =&gt;] LOCAL_NAME,
[, [External =&gt;] EXTERNAL_SYMBOL]
[, [Size =&gt;] EXTERNAL_SYMBOL]);
EXTERNAL_SYMBOL ::=
IDENTIFIER
| static_string_EXPRESSION
This pragma is identical in effect to pragma `Common_Object'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Pure" origin="Ada RM">
<DOC>Syntax:
pragma Pure [(library_unit_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Pure_Function" origin="GNAT RM">
<DOC>Syntax:
pragma Pure_Function ([Entity =&gt;] function_LOCAL_NAME);
This pragma appears in the same declarative part as a function
declaration (or a set of function declarations if more than one
overloaded declaration exists, in which case the pragma applies to all
entities). It specifies that the function `Entity' is to be considered
pure for the purposes of code generation. This means that the compiler
can assume that there are no side effects, and in particular that two
calls with identical arguments produce the same result. It also means
that the function can be used in an address clause.
Note that, quite deliberately, there are no static checks to try to
ensure that this promise is met, so `Pure_Function' can be used with
functions that are conceptually pure, even if they do modify global
variables. For example, a square root function that is instrumented to
count the number of times it is called is still conceptually pure, and
can still be optimized, even though it modifies a global variable (the
count). Memo functions are another example (where a table of previous
calls is kept and consulted to avoid re-computation).
Note also that the normal rules excluding optimization of subprograms
in pure units (when parameter types are descended from System.Address,
or when the full view of a parameter type is limited), do not apply for
the Pure_Function case. If you explicitly specify Pure_Function, the
compiler may optimize away calls with identical arguments, and if that
results in unexpected behavior, the proper action is not to use the
pragma for subprograms that are not (conceptually) pure.
Note: Most functions in a `Pure' package are automatically pure, and
there is no need to use pragma `Pure_Function' for such functions. One
exception is any function that has at least one formal of type
`System.Address' or a type derived from it. Such functions are not
considered pure by default, since the compiler assumes that the
`Address' parameter may be functioning as a pointer and that the
referenced data may change even if the address value does not.
Similarly, imported functions are not considered to be pure by default,
since there is no way of checking that they are in fact pure. The use
of pragma `Pure_Function' for such a function will override these
default assumption, and cause the compiler to treat a designated
subprogram as pure in these cases.
Note: If pragma `Pure_Function' is applied to a renamed function, it
applies to the underlying renamed function. This can be used to
disambiguate cases of overloading where some but not all functions in a
set of overloaded functions are to be designated as pure.
If pragma `Pure_Function' is applied to a library-level function, the
function is also considered pure from an optimization point of view,
but the unit is not a Pure unit in the categorization sense. So for
example, a function thus marked is free to `with' non-pure units.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Queuing_Policy" origin="Ada RM">
<DOC>Syntax:
pragma Queuing_Policy (policy_identifier);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Rational" origin="GNAT RM">
<DOC>Syntax:
pragma Rational;
This pragma is considered obsolescent, but is retained for
compatibility purposes. It is equivalent to:
pragma Profile (Rational);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Ravenscar" origin="GNAT RM">
<DOC>Syntax:
pragma Ravenscar;
This pragma is considered obsolescent, but is retained for
compatibility purposes. It is equivalent to:
pragma Profile (Ravenscar);
which is the preferred method of setting the `Ravenscar' profile.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Refined_Depends" origin="GNAT RM">
<DOC>Syntax:
pragma Refined_Depends (DEPENDENCY_RELATION);
DEPENDENCY_RELATION ::=
null
| (DEPENDENCY_CLAUSE {, DEPENDENCY_CLAUSE})
DEPENDENCY_CLAUSE ::=
OUTPUT_LIST =&gt;[+] INPUT_LIST
| NULL_DEPENDENCY_CLAUSE
NULL_DEPENDENCY_CLAUSE ::= null =&gt; INPUT_LIST
OUTPUT_LIST ::= OUTPUT | (OUTPUT {, OUTPUT})
INPUT_LIST ::= null | INPUT | (INPUT {, INPUT})
OUTPUT ::= NAME | FUNCTION_RESULT
INPUT ::= NAME
where FUNCTION_RESULT is a function Result attribute_reference
For the semantics of this pragma, see the entry for aspect
`Refined_Depends' in the SPARK 2014 Reference Manual, section 6.1.5.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Refined_Global" origin="GNAT RM">
<DOC>Syntax:
pragma Refined_Global (GLOBAL_SPECIFICATION);
GLOBAL_SPECIFICATION ::=
null
| (GLOBAL_LIST)
| (MODED_GLOBAL_LIST {, MODED_GLOBAL_LIST})
MODED_GLOBAL_LIST ::= MODE_SELECTOR =&gt; GLOBAL_LIST
MODE_SELECTOR ::= In_Out | Input | Output | Proof_In
GLOBAL_LIST ::= GLOBAL_ITEM | (GLOBAL_ITEM {, GLOBAL_ITEM})
GLOBAL_ITEM ::= NAME
For the semantics of this pragma, see the entry for aspect
`Refined_Global' in the SPARK 2014 Reference Manual, section 6.1.4.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Refined_Post" origin="GNAT RM">
<DOC>Syntax:
pragma Refined_Post (boolean_EXPRESSION);
For the semantics of this pragma, see the entry for aspect
`Refined_Post' in the SPARK 2014 Reference Manual, section 7.2.7.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Refined_State" origin="GNAT RM">
<DOC>Syntax:
pragma Refined_State (REFINEMENT_LIST);
REFINEMENT_LIST ::=
(REFINEMENT_CLAUSE {, REFINEMENT_CLAUSE})
REFINEMENT_CLAUSE ::= state_NAME =&gt; CONSTITUENT_LIST
CONSTITUENT_LIST ::=
null
| CONSTITUENT
| (CONSTITUENT {, CONSTITUENT})
CONSTITUENT ::= object_NAME | state_NAME
For the semantics of this pragma, see the entry for aspect
`Refined_State' in the SPARK 2014 Reference Manual, section 7.2.2.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Relative_Deadline" origin="GNAT RM">
<DOC>Syntax:
pragma Relative_Deadline (time_span_EXPRESSION);
This pragma is standard in Ada 2005, but is available in all earlier
versions of Ada as an implementation-defined pragma. See Ada 2012
Reference Manual for details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Remote_Access_Type" origin="GNAT RM">
<DOC>Syntax:
pragma Remote_Access_Type ([Entity =&gt;] formal_access_type_LOCAL_NAME);
This pragma appears in the formal part of a generic declaration. It
specifies an exception to the RM rule from E.2.2(17/2), which forbids
the use of a remote access to class-wide type as actual for a formal
access type.
When this pragma applies to a formal access type `Entity', that type is
treated as a remote access to class-wide type in the generic. It must
be a formal general access type, and its designated type must be the
class-wide type of a formal tagged limited private type from the same
generic declaration.
In the generic unit, the formal type is subject to all restrictions
pertaining to remote access to class-wide types. At instantiation, the
actual type must be a remote access to class-wide type.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Remote_Call_Interface" origin="Ada RM">
<DOC>Syntax:
pragma Remote_Call_Interface [(library_unit_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Remote_Types" origin="Ada RM">
<DOC>Syntax:
pragma Remote_Types [(library_unit_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Rename_Pragma" origin="GNAT RM">
<DOC>Syntax:
pragma Rename_Pragma (
[New_Name =&gt;] IDENTIFIER,
[Renamed =&gt;] pragma_IDENTIFIER);
This pragma provides a mechanism for supplying new names for existing
pragmas. The `New_Name' identifier can subsequently be used as a
synonym for the Renamed pragma. For example, suppose you have code that
was originally developed on a compiler that supports Inline_Only as an
implementation defined pragma. And suppose the semantics of pragma
Inline_Only are identical to (or at least very similar to) the GNAT
implementation defined pragma Inline_Always. You could globally replace
Inline_Only with Inline_Always.
However, to avoid that source modification, you could instead add a
configuration pragma:
pragma Rename_Pragma (
New_Name =&gt; Inline_Only,
Renamed =&gt; Inline_Always);
Then GNAT will treat "pragma Inline_Only ..." as if you had written
"pragma Inline_Always ...".
Pragma Inline_Only will not necessarily mean the same thing as the
other Ada compiler; it's up to you to make sure the semantics are close
enough.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Restricted_Run_Time" origin="GNAT RM">
<DOC>Syntax:
pragma Restricted_Run_Time;
This pragma is considered obsolescent, but is retained for
compatibility purposes. It is equivalent to:
pragma Profile (Restricted);
which is the preferred method of setting the restricted run time
profile.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Restriction_Warnings" origin="GNAT RM">
<DOC>Syntax:
pragma Restriction_Warnings
(restriction_IDENTIFIER {, restriction_IDENTIFIER});
This pragma allows a series of restriction identifiers to be specified
(the list of allowed identifiers is the same as for pragma
`Restrictions'). For each of these identifiers the compiler checks for
violations of the restriction, but generates a warning message rather
than an error message if the restriction is violated.
One use of this is in situations where you want to know about
violations of a restriction, but you want to ignore some of these
violations. Consider this example, where you want to set Ada_95 mode
and enable style checks, but you want to know about any other use of
implementation pragmas:
pragma Restriction_Warnings (No_Implementation_Pragmas);
pragma Warnings (Off, "violation of No_Implementation_Pragmas");
pragma Ada_95;
pragma Style_Checks ("2bfhkM160");
pragma Warnings (On, "violation of No_Implementation_Pragmas");
By including the above lines in a configuration pragmas file, the
Ada_95 and Style_Checks pragmas are accepted without generating a
warning, but any other use of implementation defined pragmas will cause
a warning to be generated.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Restrictions" origin="Ada RM">
<DOC>Syntax:
pragma Restrictions (restriction{, restriction});</DOC>
</PRAGMA>
<PRAGMA id="0" name="Reviewable" origin="GNAT RM">
<DOC>Syntax:
pragma Reviewable;
This pragma is an RM-defined standard pragma, but has no effect on the
program being compiled, or on the code generated for the program.
To obtain the required output specified in RM H.3.1, the compiler must
be run with various special switches as follows:
* `Where compiler-generated run-time checks remain'
The switch `-gnatGL' may be used to list the expanded code in
pseudo-Ada form. Runtime checks show up in the listing either as
explicit checks or operators marked with {} to indicate a check is
present.
* `An identification of known exceptions at compile time'
If the program is compiled with `-gnatwa', the compiler warning
messages will indicate all cases where the compiler detects that
an exception is certain to occur at run time.
* `Possible reads of uninitialized variables'
The compiler warns of many such cases, but its output is
incomplete.
The CodePeer analysis tool may be used to obtain a comprehensive list
of all possible points at which uninitialized data may be read.
* `Where run-time support routines are implicitly invoked'
In the output from `-gnatGL', run-time calls are explicitly listed
as calls to the relevant run-time routine.
* `Object code listing'
This may be obtained either by using the `-S' switch, or the
objdump utility.
* `Constructs known to be erroneous at compile time'
These are identified by warnings issued by the compiler (use
`-gnatwa').
* `Stack usage information'
Static stack usage data (maximum per-subprogram) can be obtained
via the `-fstack-usage' switch to the compiler. Dynamic stack
usage data (per task) can be obtained via the `-u' switch to
gnatbind
The gnatstack utility can be used to provide additional information on
stack usage.
* `Object code listing of entire partition'
This can be obtained by compiling the partition with `-S', or by
applying objdump to all the object files that are part of the
partition.
* `A description of the run-time model'
The full sources of the run-time are available, and the
documentation of these routines describes how these run-time
routines interface to the underlying operating system facilities.
* `Control and data-flow information'
The CodePeer tool may be used to obtain complete control and data-flow
information, as well as comprehensive messages identifying possible
problems based on this information.</DOC>
</PRAGMA>
<PRAGMA id="0" name="SPARK_Mode" origin="GNAT RM">
<DOC>Syntax:
pragma SPARK_Mode [(On | Off)] ;
In general a program can have some parts that are in SPARK 2014 (and
follow all the rules in the SPARK Reference Manual), and some parts
that are full Ada 2012.
The SPARK_Mode pragma is used to identify which parts are in SPARK 2014
(by default programs are in full Ada). The SPARK_Mode pragma can be
used in the following places:
* As a configuration pragma, in which case it sets the default mode
for all units compiled with this pragma.
* Immediately following a library-level subprogram spec
* Immediately within a library-level package body
* Immediately following the `private' keyword of a library-level
package spec
* Immediately following the `begin' keyword of a library-level
package body
* Immediately within a library-level subprogram body
Normally a subprogram or package spec/body inherits the current mode
that is active at the point it is declared. But this can be overridden
by pragma within the spec or body as above.
The basic consistency rule is that you can't turn SPARK_Mode back `On',
once you have explicitly (with a pragma) turned if `Off'. So the
following rules apply:
If a subprogram spec has SPARK_Mode `Off', then the body must also have
SPARK_Mode `Off'.
For a package, we have four parts:
* the package public declarations
* the package private part
* the body of the package
* the elaboration code after `begin'
For a package, the rule is that if you explicitly turn SPARK_Mode `Off'
for any part, then all the following parts must have SPARK_Mode `Off'.
Note that this may require repeating a pragma SPARK_Mode (`Off') in the
body. For example, if we have a configuration pragma SPARK_Mode (`On')
that turns the mode on by default everywhere, and one particular
package spec has pragma SPARK_Mode (`Off'), then that pragma will need
to be repeated in the package body.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Secondary_Stack_Size" origin="GNAT RM">
<DOC>Syntax:
pragma Secondary_Stack_Size (integer_EXPRESSION);
This pragma appears within the task definition of a single task
declaration or a task type declaration (like pragma `Storage_Size') and
applies to all task objects of that type. The argument specifies the
size of the secondary stack to be used by these task objects, and must
be of an integer type. The secondary stack is used to handle functions
that return a variable-sized result, for example a function returning
an unconstrained String.
Note this pragma only applies to targets using fixed secondary stacks,
like VxWorks 653 and bare board targets, where a fixed block for the
secondary stack is allocated from the primary stack of the task. By
default, these targets assign a percentage of the primary stack for the
secondary stack, as defined by `System.Parameter.Sec_Stack_Percentage'.
With this pragma, an `integer_EXPRESSION' of bytes is assigned from the
primary stack instead.
For most targets, the pragma does not apply as the secondary stack
grows on demand: allocated as a chain of blocks in the heap. The
default size of these blocks can be modified via the `-D' binder option
as described in `GNAT User's Guide'.
Note that no check is made to see if the secondary stack can fit inside
the primary stack.
Note the pragma cannot appear when the restriction `No_Secondary_Stack'
is in effect.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Share_Generic" origin="GNAT RM">
<DOC>Syntax:
pragma Share_Generic (GNAME {, GNAME});
GNAME ::= generic_unit_NAME | generic_instance_NAME
This pragma is provided for compatibility with Dec Ada 83. It has no
effect in GNAT (which does not implement shared generics), other than
to check that the given names are all names of generic units or generic
instances.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Shared" origin="GNAT RM">
<DOC>This pragma is provided for compatibility with Ada 83. The syntax and
semantics are identical to pragma Atomic.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Shared_Passive" origin="Ada RM">
<DOC>Syntax:
pragma Shared_Passive [(library_unit_name)];</DOC>
</PRAGMA>
<PRAGMA id="0" name="Short_Circuit_And_Or" origin="GNAT RM">
<DOC>Syntax:
pragma Short_Circuit_And_Or;
This configuration pragma causes any occurrence of the AND operator
applied to operands of type Standard.Boolean to be short-circuited
(i.e. the AND operator is treated as if it were AND THEN). Or is
similarly treated as OR ELSE. This may be useful in the context of
certification protocols requiring the use of short-circuited logical
operators. If this configuration pragma occurs locally within the file
being compiled, it applies only to the file being compiled. There is
no requirement that all units in a partition use this option.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Short_Descriptors" origin="GNAT RM">
<DOC>Syntax:
pragma Short_Descriptors
This pragma is provided for compatibility with other Ada
implementations. It is recognized but ignored by all current versions
of GNAT.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Simple_Storage_Pool_Type" origin="GNAT RM">
<DOC>Syntax:
pragma Simple_Storage_Pool_Type (type_LOCAL_NAME);
A type can be established as a 'simple storage pool type' by applying
the representation pragma `Simple_Storage_Pool_Type' to the type. A
type named in the pragma must be a library-level immutably limited
record type or limited tagged type declared immediately within a
package declaration. The type can also be a limited private type whose
full type is allowed as a simple storage pool type.
For a simple storage pool type `SSP', nonabstract primitive subprograms
`Allocate', `Deallocate', and `Storage_Size' can be declared that are
subtype conformant with the following subprogram declarations:
procedure Allocate
(Pool : in out SSP;
Storage_Address : out System.Address;
Size_In_Storage_Elements : System.Storage_Elements.Storage_Count;
Alignment : System.Storage_Elements.Storage_Count);
procedure Deallocate
(Pool : in out SSP;
Storage_Address : System.Address;
Size_In_Storage_Elements : System.Storage_Elements.Storage_Count;
Alignment : System.Storage_Elements.Storage_Count);
function Storage_Size (Pool : SSP)
return System.Storage_Elements.Storage_Count;
Procedure `Allocate' must be declared, whereas `Deallocate' and
`Storage_Size' are optional. If `Deallocate' is not declared, then
applying an unchecked deallocation has no effect other than to set its
actual parameter to null. If `Storage_Size' is not declared, then the
`Storage_Size' attribute applied to an access type associated with a
pool object of type SSP returns zero. Additional operations can be
declared for a simple storage pool type (such as for supporting a
mark/release storage-management discipline).
An object of a simple storage pool type can be associated with an access
type by specifying the attribute *note Simple_Storage_Pool: e5. For
example:
My_Pool : My_Simple_Storage_Pool_Type;
type Acc is access My_Data_Type;
for Acc'Simple_Storage_Pool use My_Pool;
See attribute *note Simple_Storage_Pool: e5. for further details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Source_File_Name" origin="GNAT RM">
<DOC>Syntax:
pragma Source_File_Name (
[Unit_Name =&gt;] unit_NAME,
Spec_File_Name =&gt; STRING_LITERAL,
[Index =&gt; INTEGER_LITERAL]);
pragma Source_File_Name (
[Unit_Name =&gt;] unit_NAME,
Body_File_Name =&gt; STRING_LITERAL,
[Index =&gt; INTEGER_LITERAL]);
Use this to override the normal naming convention. It is a
configuration pragma, and so has the usual applicability of
configuration pragmas (i.e., it applies to either an entire partition,
or to all units in a compilation, or to a single unit, depending on how
it is used. `unit_name' is mapped to `file_name_literal'. The
identifier for the second argument is required, and indicates whether
this is the file name for the spec or for the body.
The optional Index argument should be used when a file contains multiple
units, and when you do not want to use `gnatchop' to separate then into
multiple files (which is the recommended procedure to limit the number
of recompilations that are needed when some sources change). For
instance, if the source file `source.ada' contains
package B is
end B;
with B;
procedure A is
begin
end A;
you could use the following configuration pragmas:
pragma Source_File_Name
(B, Spec_File_Name =&gt; "source.ada", Index =&gt; 1);
pragma Source_File_Name
(A, Body_File_Name =&gt; "source.ada", Index =&gt; 2);
Note that the `gnatname' utility can also be used to generate those
configuration pragmas.
Another form of the `Source_File_Name' pragma allows the specification
of patterns defining alternative file naming schemes to apply to all
files.
pragma Source_File_Name
( [Spec_File_Name =&gt;] STRING_LITERAL
[,[Casing =&gt;] CASING_SPEC]
[,[Dot_Replacement =&gt;] STRING_LITERAL]);
pragma Source_File_Name
( [Body_File_Name =&gt;] STRING_LITERAL
[,[Casing =&gt;] CASING_SPEC]
[,[Dot_Replacement =&gt;] STRING_LITERAL]);
pragma Source_File_Name
( [Subunit_File_Name =&gt;] STRING_LITERAL
[,[Casing =&gt;] CASING_SPEC]
[,[Dot_Replacement =&gt;] STRING_LITERAL]);
CASING_SPEC ::= Lowercase | Uppercase | Mixedcase
The first argument is a pattern that contains a single asterisk
indicating the point at which the unit name is to be inserted in the
pattern string to form the file name. The second argument is optional.
If present it specifies the casing of the unit name in the resulting
file name string. The default is lower case. Finally the third
argument allows for systematic replacement of any dots in the unit name
by the specified string literal.
Note that Source_File_Name pragmas should not be used if you are using
project files. The reason for this rule is that the project manager is
not aware of these pragmas, and so other tools that use the projet file
would not be aware of the intended naming conventions. If you are using
project files, file naming is controlled by Source_File_Name_Project
pragmas, which are usually supplied automatically by the project
manager. A pragma Source_File_Name cannot appear after a *note Pragma
Source_File_Name_Project: e8.
For more details on the use of the `Source_File_Name' pragma, see the
sections on `Using Other File Names' and `Alternative File Naming
Schemes' in the `GNAT User's Guide'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Source_File_Name_Project" origin="GNAT RM">
<DOC>This pragma has the same syntax and semantics as pragma
Source_File_Name. It is only allowed as a stand-alone configuration
pragma. It cannot appear after a *note Pragma Source_File_Name: e6, and
most importantly, once pragma Source_File_Name_Project appears, no
further Source_File_Name pragmas are allowed.
The intention is that Source_File_Name_Project pragmas are always
generated by the Project Manager in a manner consistent with the naming
specified in a project file, and when naming is controlled in this
manner, it is not permissible to attempt to modify this naming scheme
using Source_File_Name or Source_File_Name_Project pragmas (which would
not be known to the project manager).</DOC>
</PRAGMA>
<PRAGMA id="0" name="Source_Reference" origin="GNAT RM">
<DOC>Syntax:
pragma Source_Reference (INTEGER_LITERAL, STRING_LITERAL);
This pragma must appear as the first line of a source file.
`integer_literal' is the logical line number of the line following the
pragma line (for use in error messages and debugging information).
`string_literal' is a static string constant that specifies the file
name to be used in error messages and debugging information. This is
most notably used for the output of `gnatchop' with the `-r' switch, to
make sure that the original unchopped source file is the one referred
to.
The second argument must be a string literal, it cannot be a static
string expression other than a string literal. This is because its
value is needed for error messages issued by all phases of the compiler.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Static_Elaboration_Desired" origin="GNAT RM">
<DOC>Syntax:
pragma Static_Elaboration_Desired;
This pragma is used to indicate that the compiler should attempt to
initialize statically the objects declared in the library unit to which
the pragma applies, when these objects are initialized (explicitly or
implicitly) by an aggregate. In the absence of this pragma, aggregates
in object declarations are expanded into assignments and loops, even
when the aggregate components are static constants. When the aggregate
is present the compiler builds a static expression that requires no
run-time code, so that the initialized object can be placed in
read-only data space. If the components are not static, or the
aggregate has more that 100 components, the compiler emits a warning
that the pragma cannot be obeyed. (See also the restriction
No_Implicit_Loops, which supports static construction of larger
aggregates with static components that include an others choice.)</DOC>
</PRAGMA>
<PRAGMA id="0" name="Storage_Size" origin="Ada RM">
<DOC>Syntax:
pragma Storage_Size;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Stream_Convert" origin="GNAT RM">
<DOC>Syntax:
pragma Stream_Convert (
[Entity =&gt;] type_LOCAL_NAME,
[Read =&gt;] function_NAME,
[Write =&gt;] function_NAME);
This pragma provides an efficient way of providing user-defined stream
attributes. Not only is it simpler to use than specifying the
attributes directly, but more importantly, it allows the specification
to be made in such a way that the predefined unit Ada.Streams is not
loaded unless it is actually needed (i.e. unless the stream attributes
are actually used); the use of the Stream_Convert pragma adds no
overhead at all, unless the stream attributes are actually used on the
designated type.
The first argument specifies the type for which stream functions are
provided. The second parameter provides a function used to read values
of this type. It must name a function whose argument type may be any
subtype, and whose returned type must be the type given as the first
argument to the pragma.
The meaning of the `Read' parameter is that if a stream attribute
directly or indirectly specifies reading of the type given as the first
parameter, then a value of the type given as the argument to the Read
function is read from the stream, and then the Read function is used to
convert this to the required target type.
Similarly the `Write' parameter specifies how to treat write attributes
that directly or indirectly apply to the type given as the first
parameter. It must have an input parameter of the type specified by
the first parameter, and the return type must be the same as the input
type of the Read function. The effect is to first call the Write
function to convert to the given stream type, and then write the result
type to the stream.
The Read and Write functions must not be overloaded subprograms. If
necessary renamings can be supplied to meet this requirement. The
usage of this attribute is best illustrated by a simple example, taken
from the GNAT implementation of package Ada.Strings.Unbounded:
function To_Unbounded (S : String) return Unbounded_String
renames To_Unbounded_String;
pragma Stream_Convert
(Unbounded_String, To_Unbounded, To_String);
The specifications of the referenced functions, as given in the Ada
Reference Manual are:
function To_Unbounded_String (Source : String)
return Unbounded_String;
function To_String (Source : Unbounded_String)
return String;
The effect is that if the value of an unbounded string is written to a
stream, then the representation of the item in the stream is in the
same format that would be used for `Standard.String'Output', and this
same representation is expected when a value of this type is read from
the stream. Note that the value written always includes the bounds,
even for Unbounded_String'Write, since Unbounded_String is not an array
type.
Note that the `Stream_Convert' pragma is not effective in the case of a
derived type of a non-limited tagged type. If such a type is specified
then the pragma is silently ignored, and the default implementation of
the stream attributes is used instead.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Style_Checks" origin="GNAT RM">
<DOC>Syntax:
pragma Style_Checks (string_LITERAL | ALL_CHECKS |
On | Off [, LOCAL_NAME]);
This pragma is used in conjunction with compiler switches to control the
built in style checking provided by GNAT. The compiler switches, if
set, provide an initial setting for the switches, and this pragma may
be used to modify these settings, or the settings may be provided
entirely by the use of the pragma. This pragma can be used anywhere
that a pragma is legal, including use as a configuration pragma
(including use in the `gnat.adc' file).
The form with a string literal specifies which style options are to be
activated. These are additive, so they apply in addition to any
previously set style check options. The codes for the options are the
same as those used in the `-gnaty' switch to `gcc' or `gnatmake'. For
example the following two methods can be used to enable layout checking:
* pragma Style_Checks ("l");
* gcc -c -gnatyl ...
The form `ALL_CHECKS' activates all standard checks (its use is
equivalent to the use of the `gnaty' switch with no options. See the
`GNAT User's Guide' for details.)
Note: the behavior is slightly different in GNAT mode (`-gnatg' used).
In this case, `ALL_CHECKS' implies the standard set of GNAT mode style
check options (i.e. equivalent to `-gnatyg').
The forms with `Off' and `On' can be used to temporarily disable style
checks as shown in the following example:
pragma Style_Checks ("k"); -- requires keywords in lower case
pragma Style_Checks (Off); -- turn off style checks
NULL; -- this will not generate an error message
pragma Style_Checks (On); -- turn style checks back on
NULL; -- this will generate an error message
Finally the two argument form is allowed only if the first argument is
`On' or `Off'. The effect is to turn of semantic style checks for the
specified entity, as shown in the following example:
pragma Style_Checks ("r"); -- require consistency of identifier casing
Arg : Integer;
Rf1 : Integer := ARG; -- incorrect, wrong case
pragma Style_Checks (Off, Arg);
Rf2 : Integer := ARG; -- OK, no error</DOC>
</PRAGMA>
<PRAGMA id="0" name="Subtitle" origin="GNAT RM">
<DOC>Syntax:
pragma Subtitle ([Subtitle =&gt;] STRING_LITERAL);
This pragma is recognized for compatibility with other Ada compilers
but is ignored by GNAT.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Suppress" origin="GNAT RM">
<DOC>Syntax:
pragma Suppress (Identifier [, [On =&gt;] Name]);
This is a standard pragma, and supports all the check names required in
the RM. It is included here because GNAT recognizes some additional
check names that are implementation defined (as permitted by the RM):
* `Alignment_Check' can be used to suppress alignment checks on
addresses used in address clauses. Such checks can also be
suppressed by suppressing range checks, but the specific use of
`Alignment_Check' allows suppression of alignment checks without
suppressing other range checks. Note that `Alignment_Check' is
suppressed by default on machines (such as the x86) with
non-strict alignment.
* `Atomic_Synchronization' can be used to suppress the special memory
synchronization instructions that are normally generated for
access to `Atomic' variables to ensure correct synchronization
between tasks that use such variables for synchronization purposes.
* `Duplicated_Tag_Check' Can be used to suppress the check that is
generated for a duplicated tag value when a tagged type is
declared.
* `Container_Checks' Can be used to suppress all checks within
Ada.Containers and instances of its children, including
Tampering_Check.
* `Tampering_Check' Can be used to suppress tampering check in the
containers.
* `Predicate_Check' can be used to control whether predicate checks
are active. It is applicable only to predicates for which the
policy is `Check'. Unlike `Assertion_Policy', which determines if
a given predicate is ignored or checked for the whole program, the
use of `Suppress' and `Unsuppress' with this check name allows a
given predicate to be turned on and off at specific points in the
program.
* `Validity_Check' can be used specifically to control validity
checks. If `Suppress' is used to suppress validity checks, then
no validity checks are performed, including those specified by the
appropriate compiler switch or the `Validity_Checks' pragma.
* Additional check names previously introduced by use of the
`Check_Name' pragma are also allowed.
Note that pragma Suppress gives the compiler permission to omit checks,
but does not require the compiler to omit checks. The compiler will
generate checks if they are essentially free, even when they are
suppressed. In particular, if the compiler can prove that a certain
check will necessarily fail, it will generate code to do an
unconditional 'raise', even if checks are suppressed. The compiler
warns in this case.
Of course, run-time checks are omitted whenever the compiler can prove
that they will not fail, whether or not checks are suppressed.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Suppress_All" origin="GNAT RM">
<DOC>Syntax:
pragma Suppress_All;
This pragma can appear anywhere within a unit. The effect is to apply
`Suppress (All_Checks)' to the unit in which it appears. This pragma
is implemented for compatibility with DEC Ada 83 usage where it appears
at the end of a unit, and for compatibility with Rational Ada, where it
appears as a program unit pragma. The use of the standard Ada pragma
`Suppress (All_Checks)' as a normal configuration pragma is the
preferred usage in GNAT.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Suppress_Debug_Info" origin="GNAT RM">
<DOC>Syntax:
pragma Suppress_Debug_Info ([Entity =&gt;] LOCAL_NAME);
This pragma can be used to suppress generation of debug information for
the specified entity. It is intended primarily for use in debugging the
debugger, and navigating around debugger problems.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Suppress_Exception_Locations" origin="GNAT RM">
<DOC>Syntax:
pragma Suppress_Exception_Locations;
In normal mode, a raise statement for an exception by default generates
an exception message giving the file name and line number for the
location of the raise. This is useful for debugging and logging
purposes, but this entails extra space for the strings for the
messages. The configuration pragma `Suppress_Exception_Locations' can
be used to suppress the generation of these strings, with the result
that space is saved, but the exception message for such raises is null.
This configuration pragma may appear in a global configuration pragma
file, or in a specific unit as usual. It is not required that this
pragma be used consistently within a partition, so it is fine to have
some units within a partition compiled with this pragma and others
compiled in normal mode without it.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Suppress_Initialization" origin="GNAT RM">
<DOC>Syntax:
pragma Suppress_Initialization ([Entity =&gt;] variable_or_subtype_Name);
Here variable_or_subtype_Name is the name introduced by a type
declaration or subtype declaration or the name of a variable introduced
by an object declaration.
In the case of a type or subtype this pragma suppresses any implicit or
explicit initialization for all variables of the given type or subtype,
including initialization resulting from the use of pragmas
Normalize_Scalars or Initialize_Scalars.
This is considered a representation item, so it cannot be given after
the type is frozen. It applies to all subsequent object declarations,
and also any allocator that creates objects of the type.
If the pragma is given for the first subtype, then it is considered to
apply to the base type and all its subtypes. If the pragma is given for
other than a first subtype, then it applies only to the given subtype.
The pragma may not be given after the type is frozen.
Note that this includes eliminating initialization of discriminants for
discriminated types, and tags for tagged types. In these cases, you
will have to use some non-portable mechanism (e.g. address overlays or
unchecked conversion) to achieve required initialization of these
fields before accessing any object of the corresponding type.
For the variable case, implicit initialization for the named variable
is suppressed, just as though its subtype had been given in a pragma
Suppress_Initialization, as described above.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Task_Dispatching_Policy" origin="Ada RM">
<DOC>Syntax:
pragma Task_Dispatching_Policy (policy_identifier);</DOC>
</PRAGMA>
<PRAGMA id="0" name="Task_Name" origin="GNAT RM">
<DOC>Syntax
pragma Task_Name (string_EXPRESSION);
This pragma appears within a task definition (like pragma `Priority')
and applies to the task in which it appears. The argument must be of
type String, and provides a name to be used for the task instance when
the task is created. Note that this expression is not required to be
static, and in particular, it can contain references to task
discriminants. This facility can be used to provide different names
for different tasks as they are created, as illustrated in the example
below.
The task name is recorded internally in the run-time structures and is
accessible to tools like the debugger. In addition the routine
`Ada.Task_Identification.Image' will return this string, with a unique
task address appended.
-- Example of the use of pragma Task_Name
with Ada.Task_Identification;
use Ada.Task_Identification;
with Text_IO; use Text_IO;
procedure t3 is
type Astring is access String;
task type Task_Typ (Name : access String) is
pragma Task_Name (Name.all);
end Task_Typ;
task body Task_Typ is
Nam : constant String := Image (Current_Task);
begin
Put_Line ("--&gt;" &amp; Nam (1 .. 14) &amp; "&lt;--");
end Task_Typ;
type Ptr_Task is access Task_Typ;
Task_Var : Ptr_Task;
begin
Task_Var :=
new Task_Typ (new String'("This is task 1"));
Task_Var :=
new Task_Typ (new String'("This is task 2"));
end;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Task_Storage" origin="GNAT RM">
<DOC>Syntax:
pragma Task_Storage (
[Task_Type =&gt;] LOCAL_NAME,
[Top_Guard =&gt;] static_integer_EXPRESSION);
This pragma specifies the length of the guard area for tasks. The guard
area is an additional storage area allocated to a task. A value of zero
means that either no guard area is created or a minimal guard area is
created, depending on the target. This pragma can appear anywhere a
`Storage_Size' attribute definition clause is allowed for a task type.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Test_Case" origin="GNAT RM">
<DOC>Syntax:
pragma Test_Case (
[Name =&gt;] static_string_Expression
,[Mode =&gt;] (Nominal | Robustness)
[, Requires =&gt; Boolean_Expression]
[, Ensures =&gt; Boolean_Expression]);
The `Test_Case' pragma allows defining fine-grain specifications for
use by testing tools. The compiler checks the validity of the
`Test_Case' pragma, but its presence does not lead to any modification
of the code generated by the compiler.
`Test_Case' pragmas may only appear immediately following the
(separate) declaration of a subprogram in a package declaration, inside
a package spec unit. Only other pragmas may intervene (that is appear
between the subprogram declaration and a test case).
The compiler checks that boolean expressions given in `Requires' and
`Ensures' are valid, where the rules for `Requires' are the same as the
rule for an expression in `Precondition' and the rules for `Ensures'
are the same as the rule for an expression in `Postcondition'. In
particular, attributes `'Old' and `'Result' can only be used within the
`Ensures' expression. The following is an example of use within a
package spec:
package Math_Functions is
function Sqrt (Arg : Float) return Float;
pragma Test_Case (Name =&gt; "Test 1",
Mode =&gt; Nominal,
Requires =&gt; Arg &lt; 10000,
Ensures =&gt; Sqrt'Result &lt; 10);
end Math_Functions;
The meaning of a test case is that there is at least one context where
`Requires' holds such that, if the associated subprogram is executed in
that context, then `Ensures' holds when the subprogram returns. Mode
`Nominal' indicates that the input context should also satisfy the
precondition of the subprogram, and the output context should also
satisfy its postcondition. Mode `Robustness' indicates that the
precondition and postcondition of the subprogram should be ignored for
this test case.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Thread_Local_Storage" origin="GNAT RM">
<DOC>Syntax:
pragma Thread_Local_Storage ([Entity =&gt;] LOCAL_NAME);
This pragma specifies that the specified entity, which must be a
variable declared in a library-level package, is to be marked as
"Thread Local Storage" (`TLS'). On systems supporting this (which
include Windows, Solaris, GNU/Linux, and VxWorks 6), this causes each
thread (and hence each Ada task) to see a distinct copy of the variable.
The variable must not have default initialization, and if there is an
explicit initialization, it must be either `null' for an access
variable, a static expression for a scalar variable, or a fully static
aggregate for a composite type, that is to say, an aggregate all of
whose components are static, and which does not include packed or
discriminated components.
This provides a low-level mechanism similar to that provided by the
`Ada.Task_Attributes' package, but much more efficient and is also
useful in writing interface code that will interact with foreign
threads.
If this pragma is used on a system where `TLS' is not supported, then
an error message will be generated and the program will be rejected.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Time_Slice" origin="GNAT RM">
<DOC>Syntax:
pragma Time_Slice (static_duration_EXPRESSION);
For implementations of GNAT on operating systems where it is possible
to supply a time slice value, this pragma may be used for this purpose.
It is ignored if it is used in a system that does not allow this
control, or if it appears in other than the main program unit.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Title" origin="GNAT RM">
<DOC>Syntax:
pragma Title (TITLING_OPTION [, TITLING OPTION]);
TITLING_OPTION ::=
[Title =&gt;] STRING_LITERAL,
| [Subtitle =&gt;] STRING_LITERAL
Syntax checked but otherwise ignored by GNAT. This is a listing control
pragma used in DEC Ada 83 implementations to provide a title and/or
subtitle for the program listing. The program listing generated by GNAT
does not have titles or subtitles.
Unlike other pragmas, the full flexibility of named notation is allowed
for this pragma, i.e., the parameters may be given in any order if named
notation is used, and named and positional notation can be mixed
following the normal rules for procedure calls in Ada.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Type_Invariant" origin="GNAT RM">
<DOC>Syntax:
pragma Type_Invariant
([Entity =&gt;] type_LOCAL_NAME,
[Check =&gt;] EXPRESSION);
The `Type_Invariant' pragma is intended to be an exact replacement for
the language-defined `Type_Invariant' aspect, and shares its
restrictions and semantics. It differs from the language defined
`Invariant' pragma in that it does not permit a string parameter, and
it is controlled by the assertion identifier `Type_Invariant' rather
than `Invariant'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Type_Invariant_Class" origin="GNAT RM">
<DOC>Syntax:
pragma Type_Invariant_Class
([Entity =&gt;] type_LOCAL_NAME,
[Check =&gt;] EXPRESSION);
The `Type_Invariant_Class' pragma is intended to be an exact
replacement for the language-defined `Type_Invariant'Class' aspect, and
shares its restrictions and semantics.
Note: This pragma is called `Type_Invariant_Class' rather than
`Type_Invariant'Class' because the latter would not be strictly
conforming to the allowed syntax for pragmas. The motivation for
providing pragmas equivalent to the aspects is to allow a program to be
written using the pragmas, and then compiled if necessary using an Ada
compiler that does not recognize the pragmas or aspects, but is
prepared to ignore the pragmas. The assertion policy that controls this
pragma is `Type_Invariant'Class', not `Type_Invariant_Class'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unchecked_Union" origin="GNAT RM">
<DOC>Syntax:
pragma Unchecked_Union (first_subtype_LOCAL_NAME);
This pragma is used to specify a representation of a record type that is
equivalent to a C union. It was introduced as a GNAT implementation
defined pragma in the GNAT Ada 95 mode. Ada 2005 includes an extended
version of this pragma, making it language defined, and GNAT fully
implements this extended version in all language modes (Ada 83, Ada 95,
and Ada 2005). For full details, consult the Ada 2012 Reference Manual,
section B.3.3.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unevaluated_Use_Of_Old" origin="GNAT RM">
<DOC>Syntax:
pragma Unevaluated_Use_Of_Old (Error | Warn | Allow);
This pragma controls the processing of attributes Old and Loop_Entry.
If either of these attributes is used in a potentially unevaluated
expression (e.g. the then or else parts of an if expression), then
normally this usage is considered illegal if the prefix of the attribute
is other than an entity name. The language requires this behavior for
Old, and GNAT copies the same rule for Loop_Entry.
The reason for this rule is that otherwise, we can have a situation
where we save the Old value, and this results in an exception, even
though we might not evaluate the attribute. Consider this example:
package UnevalOld is
K : Character;
procedure U (A : String; C : Boolean) -- ERROR
with Post =&gt; (if C then A(1)'Old = K else True);
end;
If procedure U is called with a string with a lower bound of 2, and C
false, then an exception would be raised trying to evaluate A(1) on
entry even though the value would not be actually used.
Although the rule guarantees against this possibility, it is sometimes
too restrictive. For example if we know that the string has a lower
bound of 1, then we will never raise an exception. The pragma
`Unevaluated_Use_Of_Old' can be used to modify this behavior. If the
argument is `Error' then an error is given (this is the default RM
behavior). If the argument is `Warn' then the usage is allowed as legal
but with a warning that an exception might be raised. If the argument
is `Allow' then the usage is allowed as legal without generating a
warning.
This pragma may appear as a configuration pragma, or in a declarative
part or package specification. In the latter case it applies to uses up
to the end of the corresponding statement sequence or sequence of
package declarations.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unimplemented_Unit" origin="GNAT RM">
<DOC>Syntax:
pragma Unimplemented_Unit;
If this pragma occurs in a unit that is processed by the compiler, GNAT
aborts with the message `xxx not implemented', where `xxx' is the name
of the current compilation unit. This pragma is intended to allow the
compiler to handle unimplemented library units in a clean manner.
The abort only happens if code is being generated. Thus you can use
specs of unimplemented packages in syntax or semantic checking mode.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Universal_Aliasing" origin="GNAT RM">
<DOC>Syntax:
pragma Universal_Aliasing [([Entity =&gt;] type_LOCAL_NAME)];
`type_LOCAL_NAME' must refer to a type declaration in the current
declarative part. The effect is to inhibit strict type-based aliasing
optimization for the given type. In other words, the effect is as
though access types designating this type were subject to pragma
No_Strict_Aliasing. For a detailed description of the strict aliasing
optimization, and the situations in which it must be suppressed, see
the section on `Optimization and Strict Aliasing' in the `GNAT User's
Guide'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Universal_Data" origin="GNAT RM">
<DOC>Syntax:
pragma Universal_Data [(library_unit_Name)];
This pragma is supported only for the AAMP target and is ignored for
other targets. The pragma specifies that all library-level objects
(Counter 0 data) associated with the library unit are to be accessed
and updated using universal addressing (24-bit addresses for AAMP5)
rather than the default of 16-bit Data Environment (DENV) addressing.
Use of this pragma will generally result in less efficient code for
references to global data associated with the library unit, but allows
such data to be located anywhere in memory. This pragma is a library
unit pragma, but can also be used as a configuration pragma (including
use in the `gnat.adc' file). The functionality of this pragma is also
available by applying the -univ switch on the compilations of units
where universal addressing of the data is desired.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unmodified" origin="GNAT RM">
<DOC>Syntax:
pragma Unmodified (LOCAL_NAME {, LOCAL_NAME});
This pragma signals that the assignable entities (variables, `out'
parameters, `in out' parameters) whose names are listed are
deliberately not assigned in the current source unit. This suppresses
warnings about the entities being referenced but not assigned, and in
addition a warning will be generated if one of these entities is in
fact assigned in the same unit as the pragma (or in the corresponding
body, or one of its subunits).
This is particularly useful for clearly signaling that a particular
parameter is not modified, even though the spec suggests that it might
be.
For the variable case, warnings are never given for unreferenced
variables whose name contains one of the substrings `DISCARD, DUMMY,
IGNORE, JUNK, UNUSED' in any casing. Such names are typically to be
used in cases where such warnings are expected. Thus it is never
necessary to use `pragma Unmodified' for such variables, though it is
harmless to do so.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unreferenced" origin="GNAT RM">
<DOC>Syntax:
pragma Unreferenced (LOCAL_NAME {, LOCAL_NAME});
pragma Unreferenced (library_unit_NAME {, library_unit_NAME});
This pragma signals that the entities whose names are listed are
deliberately not referenced in the current source unit after the
occurrence of the pragma. This suppresses warnings about the entities
being unreferenced, and in addition a warning will be generated if one
of these entities is in fact subsequently referenced in the same unit
as the pragma (or in the corresponding body, or one of its subunits).
This is particularly useful for clearly signaling that a particular
parameter is not referenced in some particular subprogram implementation
and that this is deliberate. It can also be useful in the case of
objects declared only for their initialization or finalization side
effects.
If `LOCAL_NAME' identifies more than one matching homonym in the
current scope, then the entity most recently declared is the one to
which the pragma applies. Note that in the case of accept formals, the
pragma Unreferenced may appear immediately after the keyword `do' which
allows the indication of whether or not accept formals are referenced
or not to be given individually for each accept statement.
The left hand side of an assignment does not count as a reference for
the purpose of this pragma. Thus it is fine to assign to an entity for
which pragma Unreferenced is given.
Note that if a warning is desired for all calls to a given subprogram,
regardless of whether they occur in the same unit as the subprogram
declaration, then this pragma should not be used (calls from another
unit would not be flagged); pragma Obsolescent can be used instead for
this purpose, see *note Pragma Obsolescent: ac.
The second form of pragma `Unreferenced' is used within a context
clause. In this case the arguments must be unit names of units
previously mentioned in `with' clauses (similar to the usage of pragma
`Elaborate_All'. The effect is to suppress warnings about unreferenced
units and unreferenced entities within these units.
For the variable case, warnings are never given for unreferenced
variables whose name contains one of the substrings `DISCARD, DUMMY,
IGNORE, JUNK, UNUSED' in any casing. Such names are typically to be
used in cases where such warnings are expected. Thus it is never
necessary to use `pragma Unreferenced' for such variables, though it is
harmless to do so.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unreferenced_Objects" origin="GNAT RM">
<DOC>Syntax:
pragma Unreferenced_Objects (local_subtype_NAME {, local_subtype_NAME});
This pragma signals that for the types or subtypes whose names are
listed, objects which are declared with one of these types or subtypes
may not be referenced, and if no references appear, no warnings are
given.
This is particularly useful for objects which are declared solely for
their initialization and finalization effect. Such variables are
sometimes referred to as RAII variables (Resource Acquisition Is
Initialization). Using this pragma on the relevant type (most typically
a limited controlled type), the compiler will automatically suppress
unwanted warnings about these variables not being referenced.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unreserve_All_Interrupts" origin="GNAT RM">
<DOC>Syntax:
pragma Unreserve_All_Interrupts;
Normally certain interrupts are reserved to the implementation. Any
attempt to attach an interrupt causes Program_Error to be raised, as
described in RM C.3.2(22). A typical example is the `SIGINT' interrupt
used in many systems for a `Ctrl-C' interrupt. Normally this interrupt
is reserved to the implementation, so that `Ctrl-C' can be used to
interrupt execution.
If the pragma `Unreserve_All_Interrupts' appears anywhere in any unit in
a program, then all such interrupts are unreserved. This allows the
program to handle these interrupts, but disables their standard
functions. For example, if this pragma is used, then pressing `Ctrl-C'
will not automatically interrupt execution. However, a program can
then handle the `SIGINT' interrupt as it chooses.
For a full list of the interrupts handled in a specific implementation,
see the source code for the spec of `Ada.Interrupts.Names' in file
`a-intnam.ads'. This is a target dependent file that contains the list
of interrupts recognized for a given target. The documentation in this
file also specifies what interrupts are affected by the use of the
`Unreserve_All_Interrupts' pragma.
For a more general facility for controlling what interrupts can be
handled, see pragma `Interrupt_State', which subsumes the functionality
of the `Unreserve_All_Interrupts' pragma.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unsuppress" origin="GNAT RM">
<DOC>Syntax:
pragma Unsuppress (IDENTIFIER [, [On =&gt;] NAME]);
This pragma undoes the effect of a previous pragma `Suppress'. If
there is no corresponding pragma `Suppress' in effect, it has no
effect. The range of the effect is the same as for pragma `Suppress'.
The meaning of the arguments is identical to that used in pragma
`Suppress'.
One important application is to ensure that checks are on in cases where
code depends on the checks for its correct functioning, so that the code
will compile correctly even if the compiler switches are set to suppress
checks. For example, in a program that depends on external names of
tagged types and wants to ensure that the duplicated tag check occurs
even if all run-time checks are suppressed by a compiler switch, the
following configuration pragma will ensure this test is not suppressed:
pragma Unsuppress (Duplicated_Tag_Check);
This pragma is standard in Ada 2005. It is available in all earlier
versions of Ada as an implementation-defined pragma.
Note that in addition to the checks defined in the Ada RM, GNAT
recogizes a number of implementation-defined check names. See the
description of pragma `Suppress' for full details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Unused" origin="GNAT RM">
<DOC>Syntax:
pragma Unused (LOCAL_NAME {, LOCAL_NAME});
This pragma signals that the assignable entities (variables, `out'
parameters, and `in out' parameters) whose names are listed
deliberately do not get assigned or referenced in the current source
unit after the occurrence of the pragma in the current source unit. This
suppresses warnings about the entities that are unreferenced and/or not
assigned, and, in addition, a warning will be generated if one of these
entities gets assigned or subsequently referenced in the same unit as
the pragma (in the corresponding body or one of its subunits).
This is particularly useful for clearly signaling that a particular
parameter is not modified or referenced, even though the spec suggests
that it might be.
For the variable case, warnings are never given for unreferenced
variables whose name contains one of the substrings `DISCARD, DUMMY,
IGNORE, JUNK, UNUSED' in any casing. Such names are typically to be
used in cases where such warnings are expected. Thus it is never
necessary to use `pragma Unmodified' for such variables, though it is
harmless to do so.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Use_VADS_Size" origin="GNAT RM">
<DOC>Syntax:
pragma Use_VADS_Size;
This is a configuration pragma. In a unit to which it applies, any use
of the 'Size attribute is automatically interpreted as a use of the
'VADS_Size attribute. Note that this may result in incorrect semantic
processing of valid Ada 95 or Ada 2005 programs. This is intended to
aid in the handling of existing code which depends on the
interpretation of Size as implemented in the VADS compiler. See
description of the VADS_Size attribute for further details.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Validity_Checks" origin="GNAT RM">
<DOC>Syntax:
pragma Validity_Checks (string_LITERAL | ALL_CHECKS | On | Off);
This pragma is used in conjunction with compiler switches to control the
built-in validity checking provided by GNAT. The compiler switches, if
set provide an initial setting for the switches, and this pragma may be
used to modify these settings, or the settings may be provided entirely
by the use of the pragma. This pragma can be used anywhere that a
pragma is legal, including use as a configuration pragma (including use
in the `gnat.adc' file).
The form with a string literal specifies which validity options are to
be activated. The validity checks are first set to include only the
default reference manual settings, and then a string of letters in the
string specifies the exact set of options required. The form of this
string is exactly as described for the `-gnatVx' compiler switch (see
the GNAT User's Guide for details). For example the following two
methods can be used to enable validity checking for mode `in' and `in
out' subprogram parameters:
* pragma Validity_Checks ("im");
* $ gcc -c -gnatVim ...
The form ALL_CHECKS activates all standard checks (its use is equivalent
to the use of the `gnatVa' switch).
The forms with `Off' and `On' can be used to temporarily disable
validity checks as shown in the following example:
pragma Validity_Checks ("c"); -- validity checks for copies
pragma Validity_Checks (Off); -- turn off validity checks
A := B; -- B will not be validity checked
pragma Validity_Checks (On); -- turn validity checks back on
A := C; -- C will be validity checked</DOC>
</PRAGMA>
<PRAGMA id="0" name="Volatile" origin="GNAT RM">
<DOC>Syntax:
pragma Volatile (LOCAL_NAME);
This pragma is defined by the Ada Reference Manual, and the GNAT
implementation is fully conformant with this definition. The reason it
is mentioned in this section is that a pragma of the same name was
supplied in some Ada 83 compilers, including DEC Ada 83. The Ada 95 /
Ada 2005 implementation of pragma Volatile is upwards compatible with
the implementation in DEC Ada 83.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Volatile_Components" origin="Ada RM">
<DOC>Syntax:
pragma Volatile_Components;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Volatile_Full_Access" origin="GNAT RM">
<DOC>Syntax:
pragma Volatile_Full_Access (LOCAL_NAME);
This is similar in effect to pragma Volatile, except that any reference
to the object is guaranteed to be done only with instructions that read
or write all the bits of the object. Furthermore, if the object is of a
composite type, then any reference to a subcomponent of the object is
guaranteed to read and/or write all the bits of the object.
The intention is that this be suitable for use with memory-mapped I/O
devices on some machines. Note that there are two important respects in
which this is different from `pragma Atomic'. First a reference to a
`Volatile_Full_Access' object is not a sequential action in the RM 9.10
sense and, therefore, does not create a synchronization point. Second,
in the case of `pragma Atomic', there is no guarantee that all the bits
will be accessed if the reference is not to the whole object; the
compiler is allowed (and generally will) access only part of the object
in this case.
It is not permissible to specify `Atomic' and `Volatile_Full_Access' for
the same type or object.
It is not permissible to specify `Volatile_Full_Access' for a composite
(record or array) type or object that has an `Aliased' subcomponent.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Volatile_Function" origin="GNAT RM">
<DOC>Syntax:
pragma Volatile_Function [ (boolean_EXPRESSION) ];
For the semantics of this pragma, see the entry for aspect
`Volatile_Function' in the SPARK 2014 Reference Manual, section 7.1.2.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Warning_As_Error" origin="GNAT RM">
<DOC>Syntax:
pragma Warning_As_Error (static_string_EXPRESSION);
This configuration pragma allows the programmer to specify a set of
warnings that will be treated as errors. Any warning that matches the
pattern given by the pragma argument will be treated as an error. This
gives more precise control than -gnatwe, which treats warnings as
errors.
This pragma can apply to regular warnings (messages enabled by -gnatw)
and to style warnings (messages that start with "(style)", enabled by
-gnaty).
The pattern may contain asterisks, which match zero or more characters
in the message. For example, you can use `pragma Warning_As_Error
("bits of*unused")' to treat the warning message `warning: 960 bits of
"a" unused' as an error. All characters other than asterisk are treated
as literal characters in the match. The match is case insensitive; for
example XYZ matches xyz.
Note that the pattern matches if it occurs anywhere within the warning
message string (it is not necessary to put an asterisk at the start and
the end of the message, since this is implied).
Another possibility for the static_string_EXPRESSION which works whether
or not error tags are enabled (`-gnatw.d') is to use a single `-gnatw'
tag string, enclosed in brackets, as shown in the example below, to
treat one category of warnings as errors. Note that if you want to
treat multiple categories of warnings as errors, you can use multiple
pragma Warning_As_Error.
The above use of patterns to match the message applies only to warning
messages generated by the front end. This pragma can also be applied to
warnings provided by the back end and mentioned in *note Pragma
Warnings: 11d. By using a single full `-Wxxx' switch in the pragma,
such warnings can also be treated as errors.
The pragma can appear either in a global configuration pragma file
(e.g. `gnat.adc'), or at the start of a file. Given a global
configuration pragma file containing:
pragma Warning_As_Error ("[-gnatwj]");
which will treat all obsolescent feature warnings as errors, the
following program compiles as shown (compile options here are
`-gnatwa.d -gnatl -gnatj55').
pragma Warning_As_Error ("*never assigned*");
function Warnerr return String is
X : Integer;
|
&gt;&gt;&gt; error: variable "X" is never read and
never assigned [-gnatwv] [warning-as-error]
Y : Integer;
|
&gt;&gt;&gt; warning: variable "Y" is assigned but
never read [-gnatwu]
begin
Y := 0;
return %ABC%;
|
&gt;&gt;&gt; error: use of "%" is an obsolescent
feature (RM J.2(4)), use """ instead
[-gnatwj] [warning-as-error]
end;
lines: No errors, 3 warnings (2 treated as errors)
Note that this pragma does not affect the set of warnings issued in any
way, it merely changes the effect of a matching warning if one is
produced as a result of other warnings options. As shown in this
example, if the pragma results in a warning being treated as an error,
the tag is changed from "warning:" to "error:" and the string
"[warning-as-error]" is appended to the end of the message.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Warnings" origin="GNAT RM">
<DOC>Syntax:
pragma Warnings ([TOOL_NAME,] DETAILS [, REASON]);
DETAILS ::= On | Off
DETAILS ::= On | Off, local_NAME
DETAILS ::= static_string_EXPRESSION
DETAILS ::= On | Off, static_string_EXPRESSION
TOOL_NAME ::= GNAT | GNATprove
REASON ::= Reason =&gt; STRING_LITERAL {&amp; STRING_LITERAL}
Note: in Ada 83 mode, a string literal may be used in place of a static
string expression (which does not exist in Ada 83).
Note if the second argument of `DETAILS' is a `local_NAME' then the
second form is always understood. If the intention is to use the fourth
form, then you can write `NAME &amp; ""' to force the intepretation as a
`static_string_EXPRESSION'.
Note: if the first argument is a valid `TOOL_NAME', it will be
interpreted that way. The use of the `TOOL_NAME' argument is relevant
only to users of SPARK and GNATprove, see last part of this section for
details.
Normally warnings are enabled, with the output being controlled by the
command line switch. Warnings (`Off') turns off generation of warnings
until a Warnings (`On') is encountered or the end of the current unit.
If generation of warnings is turned off using this pragma, then some or
all of the warning messages are suppressed, regardless of the setting
of the command line switches.
The `Reason' parameter may optionally appear as the last argument in
any of the forms of this pragma. It is intended purely for the purposes
of documenting the reason for the `Warnings' pragma. The compiler will
check that the argument is a static string but otherwise ignore this
argument. Other tools may provide specialized processing for this
string.
The form with a single argument (or two arguments if Reason present),
where the first argument is `ON' or `OFF' may be used as a
configuration pragma.
If the `LOCAL_NAME' parameter is present, warnings are suppressed for
the specified entity. This suppression is effective from the point
where it occurs till the end of the extended scope of the variable
(similar to the scope of `Suppress'). This form cannot be used as a
configuration pragma.
In the case where the first argument is other than `ON' or `OFF', the
third form with a single static_string_EXPRESSION argument (and possible
reason) provides more precise control over which warnings are active.
The string is a list of letters specifying which warnings are to be
activated and which deactivated. The code for these letters is the same
as the string used in the command line switch controlling warnings. For
a brief summary, use the gnatmake command with no arguments, which will
generate usage information containing the list of warnings switches
supported. For full details see the section on `Warning Message
Control' in the `GNAT User's Guide'. This form can also be used as a
configuration pragma.
The warnings controlled by the `-gnatw' switch are generated by the
front end of the compiler. The GCC back end can provide additional
warnings and they are controlled by the `-W' switch. Such warnings can
be identified by the appearance of a string of the form `[-W{xxx}]' in
the message which designates the `-W`xxx'' switch that controls the
message. The form with a single `static_string_EXPRESSION' argument
also works for these warnings, but the string must be a single full
`-W`xxx'' switch in this case. The above reference lists a few examples
of these additional warnings.
The specified warnings will be in effect until the end of the program
or another pragma `Warnings' is encountered. The effect of the pragma is
cumulative. Initially the set of warnings is the standard default set
as possibly modified by compiler switches. Then each pragma Warning
modifies this set of warnings as specified. This form of the pragma may
also be used as a configuration pragma.
The fourth form, with an `On|Off' parameter and a string, is used to
control individual messages, based on their text. The string argument
is a pattern that is used to match against the text of individual
warning messages (not including the initial "warning: " tag).
The pattern may contain asterisks, which match zero or more characters
in the message. For example, you can use `pragma Warnings (Off, "bits
of*unused")' to suppress the warning message `warning: 960 bits of "a"
unused'. No other regular expression notations are permitted. All
characters other than asterisk in these three specific cases are
treated as literal characters in the match. The match is case
insensitive, for example XYZ matches xyz.
Note that the pattern matches if it occurs anywhere within the warning
message string (it is not necessary to put an asterisk at the start and
the end of the message, since this is implied).
The above use of patterns to match the message applies only to warning
messages generated by the front end. This form of the pragma with a
string argument can also be used to control warnings provided by the
back end and mentioned above. By using a single full `-W`xxx'' switch
in the pragma, such warnings can be turned on and off.
There are two ways to use the pragma in this form. The OFF form can be
used as a configuration pragma. The effect is to suppress all warnings
(if any) that match the pattern string throughout the compilation (or
match the -W switch in the back end case).
The second usage is to suppress a warning locally, and in this case, two
pragmas must appear in sequence:
pragma Warnings (Off, Pattern);
code where given warning is to be suppressed
pragma Warnings (On, Pattern);
In this usage, the pattern string must match in the Off and On pragmas,
and (if `-gnatw.w' is given) at least one matching warning must be
suppressed.
Note: if the ON form is not found, then the effect of the OFF form
extends until the end of the file (pragma Warnings is purely textual,
so its effect does not stop at the end of the enclosing scope).
Note: to write a string that will match any warning, use the string
`"***"'. It will not work to use a single asterisk or two asterisks
since this looks like an operator name. This form with three asterisks
is similar in effect to specifying `pragma Warnings (Off)' except (if
`-gnatw.w' is given) that a matching `pragma Warnings (On, "***")' will
be required. This can be helpful in avoiding forgetting to turn
warnings back on.
Note: the debug flag `-gnatd.i' can be used to cause the compiler to
entirely ignore all WARNINGS pragmas. This can be useful in checking
whether obsolete pragmas in existing programs are hiding real problems.
Note: pragma Warnings does not affect the processing of style messages.
See separate entry for pragma Style_Checks for control of style
messages.
Users of the formal verification tool GNATprove for the SPARK subset of
Ada may use the version of the pragma with a `TOOL_NAME' parameter.
If present, `TOOL_NAME' is the name of a tool, currently either `GNAT'
for the compiler or `GNATprove' for the formal verification tool. A
given tool only takes into account pragma Warnings that do not specify
a tool name, or that specify the matching tool name. This makes it
possible to disable warnings selectively for each tool, and as a
consequence to detect useless pragma Warnings with switch `-gnatw.w'.</DOC>
</PRAGMA>
<PRAGMA id="0" name="Weak_External" origin="GNAT RM">
<DOC>Syntax:
pragma Weak_External ([Entity =&gt;] LOCAL_NAME);
`LOCAL_NAME' must refer to an object that is declared at the library
level. This pragma specifies that the given entity should be marked as a
weak symbol for the linker. It is equivalent to `__attribute__((weak))'
in GNU C and causes `LOCAL_NAME' to be emitted as a weak symbol instead
of a regular symbol, that is to say a symbol that does not have to be
resolved by the linker if used in conjunction with a pragma Import.
When a weak symbol is not resolved by the linker, its address is set to
zero. This is useful in writing interfaces to external modules that may
or may not be linked in the final executable, for example depending on
configuration settings.
If a program references at run time an entity to which this pragma has
been applied, and the corresponding symbol was not resolved at link
time, then the execution of the program is erroneous. It is not
erroneous to take the Address of such an entity, for example to guard
potential references, as shown in the example below.
Some file formats do not support weak symbols so not all target machines
support this pragma.
-- Example of the use of pragma Weak_External
package External_Module is
key : Integer;
pragma Import (C, key);
pragma Weak_External (key);
function Present return boolean;
end External_Module;
with System; use System;
package body External_Module is
function Present return boolean is
begin
return key'Address /= System.Null_Address;
end Present;
end External_Module;</DOC>
</PRAGMA>
<PRAGMA id="0" name="Wide_Character_Encoding" origin="GNAT RM">
<DOC>Syntax:
pragma Wide_Character_Encoding (IDENTIFIER | CHARACTER_LITERAL);
This pragma specifies the wide character encoding to be used in program
source text appearing subsequently. It is a configuration pragma, but
may also be used at any point that a pragma is allowed, and it is
permissible to have more than one such pragma in a file, allowing
multiple encodings to appear within the same file.
However, note that the pragma cannot immediately precede the relevant
wide character, because then the previous encoding will still be in
effect, causing "illegal character" errors.
The argument can be an identifier or a character literal. In the
identifier case, it is one of `HEX', `UPPER', `SHIFT_JIS', `EUC',
`UTF8', or `BRACKETS'. In the character literal case it is
correspondingly one of the characters `h', `u', `s', `e', `8', or `b'.
Note that when the pragma is used within a file, it affects only the
encoding within that file, and does not affect withed units, specs, or
subunits.</DOC>
</PRAGMA>
<STANDARD name="&quot;&amp;&quot;" category="function"/>
<STANDARD name="&quot;&gt;&quot;" category="function"/>
<STANDARD name="&quot;&gt;=&quot;" category="function"/>
<STANDARD name="&quot;&lt;&quot;" category="function"/>
<STANDARD name="&quot;&lt;=&quot;" category="function"/>
<STANDARD name="&quot;*&quot;" category="function"/>
<STANDARD name="&quot;**&quot;" category="function"/>
<STANDARD name="&quot;+&quot;" category="function"/>
<STANDARD name="&quot;-&quot;" category="function"/>
<STANDARD name="&quot;/&quot;" category="function"/>
<STANDARD name="&quot;/=&quot;" category="function"/>
<STANDARD name="&quot;=&quot;" category="function"/>
<STANDARD name="&quot;abs&quot;" category="function"/>
<STANDARD name="&quot;and&quot;" category="function"/>
<STANDARD name="&quot;mod&quot;" category="function"/>
<STANDARD name="&quot;not&quot;" category="function"/>
<STANDARD name="&quot;or&quot;" category="function"/>
<STANDARD name="&quot;rem&quot;" category="function"/>
<STANDARD name="&quot;xor&quot;" category="function"/>
<STANDARD name="ASCII" category="package"><FIELD name='NUL' doc='16#00#'/>
<FIELD name='SOH' doc='16#01#'/>
<FIELD name='STX' doc='16#02#'/>
<FIELD name='ETX' doc='16#03#'/>
<FIELD name='EOT' doc='16#04#'/>
<FIELD name='ENQ' doc='16#05#'/>
<FIELD name='ACK' doc='16#06#'/>
<FIELD name='BEL' doc='16#07#'/>
<FIELD name='BS' doc='16#08#'/>
<FIELD name='HT' doc='16#09#'/>
<FIELD name='LF' doc='16#0A#'/>
<FIELD name='VT' doc='16#0B#'/>
<FIELD name='FF' doc='16#0C#'/>
<FIELD name='CR' doc='16#0D#'/>
<FIELD name='SO' doc='16#0E#'/>
<FIELD name='SI' doc='16#0F#'/>
<FIELD name='DLE' doc='16#10#'/>
<FIELD name='DC1' doc='16#11#'/>
<FIELD name='DC2' doc='16#12#'/>
<FIELD name='DC3' doc='16#13#'/>
<FIELD name='DC4' doc='16#14#'/>
<FIELD name='NAK' doc='16#15#'/>
<FIELD name='SYN' doc='16#16#'/>
<FIELD name='ETB' doc='16#17#'/>
<FIELD name='CAN' doc='16#18#'/>
<FIELD name='EM' doc='16#19#'/>
<FIELD name='SUB' doc='16#1A#'/>
<FIELD name='ESC' doc='16#1B#'/>
<FIELD name='FS' doc='16#1C#'/>
<FIELD name='GS' doc='16#1D#'/>
<FIELD name='RS' doc='16#1E#'/>
<FIELD name='US' doc='16#1F#'/>
<FIELD name='Exclam' doc='16#21#'/>
<FIELD name='Quotation' doc='16#22#'/>
<FIELD name='Sharp' doc='16#23#'/>
<FIELD name='Dollar' doc='16#24#'/>
<FIELD name='Percent' doc='16#25#'/>
<FIELD name='Ampersand' doc='16#26#'/>
<FIELD name='Colon' doc='16#3A#'/>
<FIELD name='Semicolon' doc='16#3B#'/>
<FIELD name='Query' doc='16#3F#'/>
<FIELD name='At_Sign' doc='16#40#'/>
<FIELD name='L_Bracket' doc='16#5B#'/>
<FIELD name='Back_Slash' doc='16#5C#'/>
<FIELD name='R_Bracket' doc='16#5D#'/>
<FIELD name='Circumflex' doc='16#5E#'/>
<FIELD name='Underline' doc='16#5F#'/>
<FIELD name='Grave' doc='16#60#'/>
<FIELD name='LC_A' doc='16#61#'/>
<FIELD name='LC_B' doc='16#62#'/>
<FIELD name='LC_C' doc='16#63#'/>
<FIELD name='LC_D' doc='16#64#'/>
<FIELD name='LC_E' doc='16#65#'/>
<FIELD name='LC_F' doc='16#66#'/>
<FIELD name='LC_G' doc='16#67#'/>
<FIELD name='LC_H' doc='16#68#'/>
<FIELD name='LC_I' doc='16#69#'/>
<FIELD name='LC_J' doc='16#6A#'/>
<FIELD name='LC_K' doc='16#6B#'/>
<FIELD name='LC_L' doc='16#6C#'/>
<FIELD name='LC_M' doc='16#6D#'/>
<FIELD name='LC_N' doc='16#6E#'/>
<FIELD name='LC_O' doc='16#6F#'/>
<FIELD name='LC_P' doc='16#70#'/>
<FIELD name='LC_Q' doc='16#71#'/>
<FIELD name='LC_R' doc='16#72#'/>
<FIELD name='LC_S' doc='16#73#'/>
<FIELD name='LC_T' doc='16#74#'/>
<FIELD name='LC_U' doc='16#75#'/>
<FIELD name='LC_V' doc='16#76#'/>
<FIELD name='LC_W' doc='16#77#'/>
<FIELD name='LC_X' doc='16#78#'/>
<FIELD name='LC_Y' doc='16#79#'/>
<FIELD name='LC_Z' doc='16#7A#'/>
<FIELD name='L_BRACE' doc='16#7B#'/>
<FIELD name='BA' doc='16#7C#'/>
<FIELD name='R_BRACE' doc='16#7D#'/>
<FIELD name='TILDE' doc='16#7E#'/>
<FIELD name='DEL' doc='16#7F#'/></STANDARD>
<STANDARD name="Boolean" category="type"/>
<STANDARD name="Character" category="type"/>
<STANDARD name="Constraint_Error" category="variable"/>
<STANDARD name="Duration" category="type"/>
<STANDARD name="False" category="variable"/>
<STANDARD name="Float" category="type"/>
<STANDARD name="Integer" category="type"/>
<STANDARD name="Long_Float" category="type"/>
<STANDARD name="Long_Integer" category="type"/>
<STANDARD name="Long_Long_Float" category="type"/>
<STANDARD name="Long_Long_Integer" category="type"/>
<STANDARD name="Natural" category="type"/>
<STANDARD name="Numeric_Error" category="variable"/>
<STANDARD name="Positive" category="type"/>
<STANDARD name="Program_Error" category="variable"/>
<STANDARD name="Short_Float" category="type"/>
<STANDARD name="Short_Integer" category="type"/>
<STANDARD name="Short_Short_Integer" category="type"/>
<STANDARD name="Storage_Error" category="variable"/>
<STANDARD name="String" category="type"/>
<STANDARD name="Tasking_Error" category="variable"/>
<STANDARD name="True" category="variable"/>
<STANDARD name="Wide_Character" category="type"/>
<STANDARD name="Wide_String" category="type"/>
<STANDARD name="Wide_Wide_Character" category="type"/>
<STANDARD name="Wide_Wide_String" category="type"/>
</PREDEFINED_ADA>
Reference in New Issue View Git Blame Copy Permalink