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79 lines
3.0 KiB
79 lines
3.0 KiB
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
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# file Copyright.txt or https://cmake.org/licensing for details.
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#[=======================================================================[.rst:
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CheckCXXSymbolExists
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--------------------
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Check if a symbol exists as a function, variable, or macro in ``C++``.
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.. command:: check_cxx_symbol_exists
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.. code-block:: cmake
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check_cxx_symbol_exists(<symbol> <files> <variable>)
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Check that the ``<symbol>`` is available after including given header
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``<files>`` and store the result in a ``<variable>``. Specify the list of
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files in one argument as a semicolon-separated list.
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``check_cxx_symbol_exists()`` can be used to check for symbols as seen by
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the C++ compiler, as opposed to :command:`check_symbol_exists`, which always
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uses the ``C`` compiler.
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If the header files define the symbol as a macro it is considered
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available and assumed to work. If the header files declare the symbol
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as a function or variable then the symbol must also be available for
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linking. If the symbol is a type, enum value, or C++ template it will
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not be recognized: consider using the :module:`CheckTypeSize`
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or :module:`CheckSourceCompiles` module instead.
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.. note::
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This command is unreliable when ``<symbol>`` is (potentially) an overloaded
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function. Since there is no reliable way to predict whether a given function
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in the system environment may be defined as an overloaded function or may be
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an overloaded function on other systems or will become so in the future, it
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is generally advised to use the :module:`CheckCXXSourceCompiles` module for
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checking any function symbol (unless somehow you surely know the checked
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function is not overloaded on other systems or will not be so in the
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future).
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The following variables may be set before calling this macro to modify
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the way the check is run:
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``CMAKE_REQUIRED_FLAGS``
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string of compile command line flags.
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``CMAKE_REQUIRED_DEFINITIONS``
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a :ref:`;-list <CMake Language Lists>` of macros to define (-DFOO=bar).
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``CMAKE_REQUIRED_INCLUDES``
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a :ref:`;-list <CMake Language Lists>` of header search paths to pass to
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the compiler.
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``CMAKE_REQUIRED_LINK_OPTIONS``
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.. versionadded:: 3.14
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a :ref:`;-list <CMake Language Lists>` of options to add to the link command.
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``CMAKE_REQUIRED_LIBRARIES``
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a :ref:`;-list <CMake Language Lists>` of libraries to add to the link
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command. See policy :policy:`CMP0075`.
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``CMAKE_REQUIRED_QUIET``
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.. versionadded:: 3.1
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execute quietly without messages.
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For example:
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.. code-block:: cmake
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include(CheckCXXSymbolExists)
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# Check for macro SEEK_SET
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check_cxx_symbol_exists(SEEK_SET "cstdio" HAVE_SEEK_SET)
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# Check for function std::fopen
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check_cxx_symbol_exists(std::fopen "cstdio" HAVE_STD_FOPEN)
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#]=======================================================================]
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include_guard(GLOBAL)
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include(CheckSymbolExists)
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macro(CHECK_CXX_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
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__CHECK_SYMBOL_EXISTS_IMPL(CheckSymbolExists.cxx "${SYMBOL}" "${FILES}" "${VARIABLE}" )
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endmacro()
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