82 lines
2.1 KiB
ReStructuredText
82 lines
2.1 KiB
ReStructuredText
.. title:: clang-tidy - modernize-use-nodiscard
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modernize-use-nodiscard
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=======================
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Adds ``[[nodiscard]]`` attributes (introduced in C++17) to member functions in
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order to highlight at compile time which return values should not be ignored.
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Member functions need to satisfy the following conditions to be considered by
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this check:
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- no ``[[nodiscard]]``, ``[[noreturn]]``,
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``__attribute__((warn_unused_result))``,
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``[[clang::warn_unused_result]]`` nor ``[[gcc::warn_unused_result]]``
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attribute,
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- non-void return type,
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- non-template return types,
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- const member function,
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- non-variadic functions,
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- no non-const reference parameters,
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- no pointer parameters,
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- no template parameters,
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- no template function parameters,
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- not be a member of a class with mutable member variables,
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- no Lambdas,
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- no conversion functions.
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Such functions have no means of altering any state or passing values other than
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via the return type. Unless the member functions are altering state via some
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external call (e.g. I/O).
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Example
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-------
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.. code-block:: c++
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bool empty() const;
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bool empty(int i) const;
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transforms to:
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.. code-block:: c++
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[[nodiscard]] bool empty() const;
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[[nodiscard]] bool empty(int i) const;
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Options
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-------
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.. option:: ReplacementString
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Specifies a macro to use instead of ``[[nodiscard]]``. This is useful when
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maintaining source code that needs to compile with a pre-C++17 compiler.
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Example
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^^^^^^^
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.. code-block:: c++
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bool empty() const;
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bool empty(int i) const;
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transforms to:
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.. code-block:: c++
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NO_DISCARD bool empty() const;
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NO_DISCARD bool empty(int i) const;
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if the :option:`ReplacementString` option is set to `NO_DISCARD`.
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.. note::
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If the :option:`ReplacementString` is not a C++ attribute, but instead a
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macro, then that macro must be defined in scope or the fix-it will not be
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applied.
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.. note::
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For alternative ``__attribute__`` syntax options to mark functions as
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``[[nodiscard]]`` in non-c++17 source code.
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See https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result
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