64 lines
1.6 KiB
ReStructuredText
64 lines
1.6 KiB
ReStructuredText
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.. title:: clang-tidy - performance-unnecessary-value-param
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performance-unnecessary-value-param
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===================================
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Flags value parameter declarations of expensive to copy types that are copied
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for each invocation but it would suffice to pass them by const reference.
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The check is only applied to parameters of types that are expensive to copy
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which means they are not trivially copyable or have a non-trivial copy
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constructor or destructor.
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To ensure that it is safe to replace the value parameter with a const reference
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the following heuristic is employed:
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1. the parameter is const qualified;
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2. the parameter is not const, but only const methods or operators are invoked
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on it, or it is used as const reference or value argument in constructors or
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function calls.
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Example:
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.. code-block:: c++
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void f(const string Value) {
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// The warning will suggest making Value a reference.
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}
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void g(ExpensiveToCopy Value) {
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// The warning will suggest making Value a const reference.
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Value.ConstMethd();
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ExpensiveToCopy Copy(Value);
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}
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If the parameter is not const, only copied or assigned once and has a
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non-trivial move-constructor or move-assignment operator respectively the check
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will suggest to move it.
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Example:
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.. code-block:: c++
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void setValue(string Value) {
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Field = Value;
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}
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Will become:
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.. code-block:: c++
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#include <utility>
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void setValue(string Value) {
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Field = std::move(Value);
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}
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Options
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-------
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.. option:: IncludeStyle
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A string specifying which include-style is used, `llvm` or `google`. Default
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is `llvm`.
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