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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file LICENSE.rst or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
CheckSourceCompiles
----------------------
.. versionadded:: 3.19
This module provides a command that checks whether a source code can be
built for a given language.
Load this module in a CMake project with:
.. code-block:: cmake
include(CheckSourceCompiles)
Commands
^^^^^^^^
This module provides the following command:
.. command:: check_source_compiles
Checks once whether the given source code can be built for the given
language:
.. code-block:: cmake
check_source_compiles(
<lang>
<code>
<variable>
[FAIL_REGEX <regexes>...]
[SRC_EXT <extension>]
)
This command checks once that the source supplied in ``<code>`` can be
compiled (and linked into an executable) for code language ``<lang>``.
The result of the check is stored in the internal cache variable specified
by ``<variable>``.
The arguments are:
``<lang>``
Language of the source code to check. Supported languages are:
``C``, ``CXX``, ``CUDA``, ``Fortran``, ``HIP``, ``ISPC``, ``OBJC``,
``OBJCXX``, and ``Swift``.
.. versionadded:: 3.21
Support for ``HIP`` language.
.. versionadded:: 3.26
Support for ``Swift`` language.
``<code>``
The source code to check. This must be an entire program, as written
in a file containing the body block. All symbols used in the source code
are expected to be declared as usual in their corresponding headers.
``<variable>``
Variable name of an internal cache variable to store the result of the
check, with boolean true for success and boolean false for failure.
``FAIL_REGEX <regexes>...``
If one or more regular expression patterns are provided, then failure is
determined by checking if anything in the compiler output matches any of
the specified regular expressions.
``SRC_EXT <extension>``
By default, the internal test source file used for the check will be
given a file extension that matches the requested language (e.g., ``.c``
for C, ``.cxx`` for C++, ``.F90`` for Fortran, etc.). This option can
be used to override this with the ``.<extension>`` instead.
.. rubric:: Variables Affecting the Check
The following variables may be set before calling this command to modify
the way the check is run:
.. include:: /module/include/CMAKE_REQUIRED_FLAGS.rst
.. include:: /module/include/CMAKE_REQUIRED_DEFINITIONS.rst
.. include:: /module/include/CMAKE_REQUIRED_INCLUDES.rst
.. include:: /module/include/CMAKE_REQUIRED_LINK_OPTIONS.rst
.. include:: /module/include/CMAKE_REQUIRED_LIBRARIES.rst
.. include:: /module/include/CMAKE_REQUIRED_LINK_DIRECTORIES.rst
.. include:: /module/include/CMAKE_REQUIRED_QUIET.rst
.. include:: /module/include/CMAKE_TRY_COMPILE_TARGET_TYPE.rst
Examples
^^^^^^^^
Example: Basic Usage
""""""""""""""""""""
The following example demonstrates how to check whether the C++ compiler
supports a specific language feature using this module. In this case, the
check verifies if the compiler supports ``C++11`` lambda expressions. The
result is stored in the internal cache variable ``HAVE_CXX11_LAMBDAS``:
.. code-block:: cmake
include(CheckSourceCompiles)
check_source_compiles(CXX "
int main()
{
auto lambda = []() { return 42; };
return lambda();
}
" HAVE_CXX11_LAMBDAS)
Example: Checking Code With Bracket Argument
""""""""""""""""""""""""""""""""""""""""""""
The following example shows how to check whether the C compiler supports the
``noreturn`` attribute. Code is supplied using the :ref:`Bracket Argument`
for easier embedded quotes handling:
.. code-block:: cmake
:force:
include(CheckSourceCompiles)
check_source_compiles(C [[
#if !__has_c_attribute(noreturn)
# error "No noreturn attribute"
#endif
int main(void) { return 0; }
]] HAVE_NORETURN)
Example: Performing a Check Without Linking
"""""""""""""""""""""""""""""""""""""""""""
In the following example, this module is used to perform a compile-only
check of Fortran source code, whether the compiler supports the ``pure``
procedure attribute:
.. code-block:: cmake
include(CheckSourceCompiles)
block()
set(CMAKE_TRY_COMPILE_TARGET_TYPE "STATIC_LIBRARY")
check_source_compiles(
Fortran
"pure subroutine foo()
end subroutine"
HAVE_PURE
)
endblock()
Example: Isolated Check
"""""""""""""""""""""""
In the following example, this module is used in combination with the
:module:`CMakePushCheckState` module to modify required libraries when
checking whether the PostgreSQL ``PGVerbosity`` enum contains
``PQERRORS_SQLSTATE`` (available as of PostgreSQL version 12):
.. code-block:: cmake
include(CheckSourceCompiles)
include(CMakePushCheckState)
find_package(PostgreSQL)
if(TARGET PostgreSQL::PostgreSQL)
cmake_push_check_state(RESET)
set(CMAKE_REQUIRED_LIBRARIES PostgreSQL::PostgreSQL)
check_source_compiles(C "
#include <libpq-fe.h>
int main(void)
{
PGVerbosity e = PQERRORS_SQLSTATE;
(void)e;
return 0;
}
" HAVE_PQERRORS_SQLSTATE)
cmake_pop_check_state()
endif()
See Also
^^^^^^^^
* The :module:`CheckSourceRuns` module to check whether the source code can
be built and also run.
#]=======================================================================]
include_guard(GLOBAL)
include(Internal/CheckSourceCompiles)
function(CHECK_SOURCE_COMPILES _lang _source _var)
cmake_check_source_compiles(${_lang} "${_source}" ${_var} ${ARGN})
endfunction()
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