qapi: Test for various name collisions

Expose some weaknesses in the generator: we don't always forbid
the generation of structs that contain multiple members that map
to the same C or QMP name.  This has already been marked FIXME in
qapi.py in commit d90675f, but having more tests will make sure
future patches produce desired behavior; and updating existing
patches to better document things doesn't hurt, either.  Some of
these collisions are already caught in the old-style parser
checks, but ultimately we want all collisions to be caught in the
new-style QAPISchema*.check() methods.

This patch focuses on C struct members, and does not consider
collisions between commands and events (affecting C function
names), or even collisions between generated C type names with
user type names (for things like automatic FOOList struct
representing array types or FOOKind for an implicit enum).

There are two types of struct collisions we want to catch:
 1) Collision between two keys in a JSON object. qapi.py prevents
    that within a single struct (see test duplicate-key), but it is
    possible to have collisions between a type's members and its
    base type's members (existing tests struct-base-clash,
    struct-base-clash-deep), and its flat union variant members
    (renamed test flat-union-clash-member).
 2) Collision between two members of the C struct that is generated
    for a given QAPI type:
    a) Multiple QAPI names map to the same C name (new test
       args-name-clash)
    b) A QAPI name maps to a C name that is used for another purpose
       (new tests flat-union-clash-branch, struct-base-clash-base,
       union-clash-data). We already fixed some such cases in commit
       0f61af3e and 1e6c1616, but more remain.
    c) Two C names generated for other purposes clash
       (updated test alternate-clash, new test union-clash-branches,
       union-clash-type, flat-union-clash-type)

Ultimately, if we need to have a flat union where a tag value
clashes with a base member name, we could change the generator to
name the union (using 'foo.u.value' rather than 'foo.value') or
otherwise munge the C name corresponding to tag values.  But
unless such a need arises, it will probably be easier to just
forbid these collisions.

Some of these negative tests will be deleted later, and positive
tests added to qapi-schema-test.json in their place, when the
generator code is reworked to avoid particular code generation
collisions in class 2).

[Note that viewing this patch with git rename detection enabled
may see some confusion due to renaming some tests while adding
others, but where the content is similar enough that git picks
the wrong pre- and post-patch files to associate]

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-6-git-send-email-eblake@redhat.com>
[Improve commit message and comments a bit, drop an unrelated test]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

tests/Makefile

@@ -241,6 +241,7 @@ qapi-schema += args-invalid.json
 qapi-schema += args-member-array-bad.json
 qapi-schema += args-member-array.json
 qapi-schema += args-member-unknown.json
+qapi-schema += args-name-clash.json
 qapi-schema += args-union.json
 qapi-schema += args-unknown.json
 qapi-schema += bad-base.json
@@ -276,7 +277,9 @@ qapi-schema += flat-union-bad-base.json
 qapi-schema += flat-union-bad-discriminator.json
 qapi-schema += flat-union-base-any.json
 qapi-schema += flat-union-base-union.json
-qapi-schema += flat-union-branch-clash.json
+qapi-schema += flat-union-clash-branch.json
+qapi-schema += flat-union-clash-member.json
+qapi-schema += flat-union-clash-type.json
 qapi-schema += flat-union-inline.json
 qapi-schema += flat-union-int-branch.json
 qapi-schema += flat-union-invalid-branch-key.json
@@ -318,6 +321,7 @@ qapi-schema += returns-dict.json
 qapi-schema += returns-int.json
 qapi-schema += returns-unknown.json
 qapi-schema += returns-whitelist.json
+qapi-schema += struct-base-clash-base.json
 qapi-schema += struct-base-clash-deep.json
 qapi-schema += struct-base-clash.json
 qapi-schema += struct-data-invalid.json
@@ -331,6 +335,9 @@ qapi-schema += unclosed-string.json
 qapi-schema += unicode-str.json
 qapi-schema += union-bad-branch.json
 qapi-schema += union-base-no-discriminator.json
+qapi-schema += union-clash-branches.json
+qapi-schema += union-clash-data.json
+qapi-schema += union-clash-type.json
 qapi-schema += union-invalid-base.json
 qapi-schema += union-max.json
 qapi-schema += union-optional-branch.json

tests/qapi-schema/alternate-clash.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-clash.json:2: Alternate 'Alt1' member 'ONE' clashes with 'one'
+tests/qapi-schema/alternate-clash.json:7: Alternate 'Alt1' member 'a_b' clashes with 'a-b'

tests/qapi-schema/alternate-clash.json

@@ -1,3 +1,8 @@
-# we detect C enum collisions in an alternate
+# Alternate branch name collision
+# Reject an alternate that would result in a collision in generated C
+# names (this would try to generate two enum values 'ALT1_KIND_A_B').
+# TODO: In the future, if alternates are simplified to not generate
+# the implicit Alt1Kind enum, we would still have a collision with the
+# resulting C union trying to have two members named 'a_b'.
 { 'alternate': 'Alt1',
-  'data': { 'one': 'str', 'ONE': 'int' } }
+  'data': { 'a-b': 'str', 'a_b': 'int' } }

tests/qapi-schema/args-name-clash.exit

@@ -0,0 +1 @@
+0

tests/qapi-schema/args-name-clash.json

@@ -0,0 +1,5 @@
+# C member name collision
+# FIXME - This parses, but fails to compile, because the C struct is given
+# two 'a_b' members.  Either reject this at parse time, or munge the C names
+# to avoid the collision.
+{ 'command': 'oops', 'data': { 'a-b': 'str', 'a_b': 'str' } }

tests/qapi-schema/args-name-clash.out

@@ -0,0 +1,6 @@
+object :empty
+object :obj-oops-arg
+    member a-b: str optional=False
+    member a_b: str optional=False
+command oops :obj-oops-arg -> None
+   gen=True success_response=True

tests/qapi-schema/duplicate-key.err

@@ -1 +1 @@
-tests/qapi-schema/duplicate-key.json:2:10: Duplicate key "key"
+tests/qapi-schema/duplicate-key.json:3:10: Duplicate key "key"

tests/qapi-schema/duplicate-key.json

@@ -1,2 +1,3 @@
+# QAPI cannot include the same key more than once in any {}
 { 'key': 'value',
   'key': 'value' }

tests/qapi-schema/flat-union-base-union.err

@@ -1 +1 @@
-tests/qapi-schema/flat-union-base-union.json:11: Base 'UnionBase' is not a valid struct
+tests/qapi-schema/flat-union-base-union.json:14: Base 'UnionBase' is not a valid struct

tests/qapi-schema/flat-union-base-union.json

@@ -1,4 +1,7 @@
-# we require the base to be a struct
+# For now, we require the base to be a struct without variants
+# TODO: It would be possible to allow a union as a base, as long as all
+# permutations of QMP names exposed by base do not clash with any QMP
+# member names added by local variants.
 { 'enum': 'TestEnum',
   'data': [ 'value1', 'value2' ] }
 { 'struct': 'TestTypeA',

tests/qapi-schema/flat-union-branch-clash.err

@@ -1 +0,0 @@
-tests/qapi-schema/flat-union-branch-clash.json:10: Member name 'name' of branch 'value1' clashes with base 'Base'

tests/qapi-schema/flat-union-clash-branch.exit

@@ -0,0 +1 @@
+0

tests/qapi-schema/flat-union-clash-branch.json

@@ -0,0 +1,18 @@
+# Flat union branch name collision
+# FIXME: this parses, but then fails to compile due to a duplicate 'c_d'
+# (one from the base member, the other from the branch name).  We should
+# either reject the collision at parse time, or munge the generated branch
+# name to allow this to compile.
+{ 'enum': 'TestEnum',
+  'data': [ 'base', 'c-d' ] }
+{ 'struct': 'Base',
+  'data': { 'enum1': 'TestEnum', '*c_d': 'str' } }
+{ 'struct': 'Branch1',
+  'data': { 'string': 'str' } }
+{ 'struct': 'Branch2',
+  'data': { 'value': 'int' } }
+{ 'union': 'TestUnion',
+  'base': 'Base',
+  'discriminator': 'enum1',
+  'data': { 'base': 'Branch1',
+            'c-d': 'Branch2' } }

tests/qapi-schema/flat-union-clash-branch.out

@@ -0,0 +1,14 @@
+object :empty
+object Base
+    member enum1: TestEnum optional=False
+    member c_d: str optional=True
+object Branch1
+    member string: str optional=False
+object Branch2
+    member value: int optional=False
+enum TestEnum ['base', 'c-d']
+object TestUnion
+    base Base
+    tag enum1
+    case base: Branch1
+    case c-d: Branch2

tests/qapi-schema/flat-union-clash-member.err

@@ -0,0 +1 @@
+tests/qapi-schema/flat-union-clash-member.json:11: Member name 'name' of branch 'value1' clashes with base 'Base'

tests/qapi-schema/flat-union-clash-member.json

@@ -1,4 +1,5 @@
-# we check for no duplicate keys between branches and base
+# We check for no duplicate keys between branch members and base
+# base's member 'name' clashes with Branch1's
 { 'enum': 'TestEnum',
   'data': [ 'value1', 'value2' ] }
 { 'struct': 'Base',