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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
CheckSymbolExists
-----------------
Provides a macro to check if a symbol exists as a function, variable,
or macro in ``C``.
.. command:: check_symbol_exists
.. code-block:: cmake
check_symbol_exists(<symbol> <files> <variable>)
Check that the ``<symbol>`` is available after including given header
``<files>`` and store the result in a ``<variable>``. Specify the list
of files in one argument as a semicolon-separated list.
``<variable>`` will be created as an internal cache variable.
If the header files define the symbol as a macro it is considered
available and assumed to work. If the header files declare the symbol
as a function or variable then the symbol must also be available for
linking (so intrinsics may not be detected).
If the symbol is a type, enum value, or intrinsic it will not be recognized
(consider using :module:`CheckTypeSize` or :module:`CheckCSourceCompiles`).
If the check needs to be done in C++, consider using
:module:`CheckCXXSymbolExists` instead.
The following variables may be set before calling this macro to modify
the way the check is run:
``CMAKE_REQUIRED_FLAGS``
string of compile command line flags.
``CMAKE_REQUIRED_DEFINITIONS``
a :ref:`;-list <CMake Language Lists>` of macros to define (-DFOO=bar).
``CMAKE_REQUIRED_INCLUDES``
a :ref:`;-list <CMake Language Lists>` of header search paths to pass to
the compiler.
``CMAKE_REQUIRED_LINK_OPTIONS``
a :ref:`;-list <CMake Language Lists>` of options to add to the link command.
``CMAKE_REQUIRED_LIBRARIES``
a :ref:`;-list <CMake Language Lists>` of libraries to add to the link
command. See policy :policy:`CMP0075`.
``CMAKE_REQUIRED_QUIET``
execute quietly without messages.
For example:
.. code-block:: cmake
include(CheckSymbolExists)
# Check for macro SEEK_SET
check_symbol_exists(SEEK_SET "stdio.h" HAVE_SEEK_SET)
# Check for function fopen
check_symbol_exists(fopen "stdio.h" HAVE_FOPEN)
#]=======================================================================]
if(__CheckSymbolExists_cmake__)
return()
endif()
set(__CheckSymbolExists_cmake__ TRUE)
cmake_policy(PUSH)
cmake_policy(SET CMP0054 NEW) # if() quoted variables not dereferenced
macro(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
if(CMAKE_C_COMPILER_LOADED)
__CHECK_SYMBOL_EXISTS_IMPL("${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c" "${SYMBOL}" "${FILES}" "${VARIABLE}" )
elseif(CMAKE_CXX_COMPILER_LOADED)
__CHECK_SYMBOL_EXISTS_IMPL("${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.cxx" "${SYMBOL}" "${FILES}" "${VARIABLE}" )
else()
message(FATAL_ERROR "CHECK_SYMBOL_EXISTS needs either C or CXX language enabled")
endif()
endmacro()
macro(__CHECK_SYMBOL_EXISTS_IMPL SOURCEFILE SYMBOL FILES VARIABLE)
if(NOT DEFINED "${VARIABLE}" OR "x${${VARIABLE}}" STREQUAL "x${VARIABLE}")
set(CMAKE_CONFIGURABLE_FILE_CONTENT "/* */\n")
set(MACRO_CHECK_SYMBOL_EXISTS_FLAGS ${CMAKE_REQUIRED_FLAGS})
if(CMAKE_REQUIRED_LINK_OPTIONS)
set(CHECK_SYMBOL_EXISTS_LINK_OPTIONS
LINK_OPTIONS ${CMAKE_REQUIRED_LINK_OPTIONS})
else()
set(CHECK_SYMBOL_EXISTS_LINK_OPTIONS)
endif()
if(CMAKE_REQUIRED_LIBRARIES)
set(CHECK_SYMBOL_EXISTS_LIBS
LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
else()
set(CHECK_SYMBOL_EXISTS_LIBS)
endif()
if(CMAKE_REQUIRED_INCLUDES)
set(CMAKE_SYMBOL_EXISTS_INCLUDES
"-DINCLUDE_DIRECTORIES:STRING=${CMAKE_REQUIRED_INCLUDES}")
else()
set(CMAKE_SYMBOL_EXISTS_INCLUDES)
endif()
foreach(FILE ${FILES})
string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT
"#include <${FILE}>\n")
endforeach()
string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT "
int main(int argc, char** argv)
{
(void)argv;")
set(_CSE_CHECK_NON_MACRO "return ((int*)(&${SYMBOL}))[argc];")
if("${SYMBOL}" MATCHES "^[a-zA-Z_][a-zA-Z0-9_]*$")
# The SYMBOL has a legal macro name. Test whether it exists as a macro.
string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT "
#ifndef ${SYMBOL}
${_CSE_CHECK_NON_MACRO}
#else
(void)argc;
return 0;
#endif")
else()
# The SYMBOL cannot be a macro (e.g., a template function).
string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT "
${_CSE_CHECK_NON_MACRO}")
endif()
string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT "
}")
unset(_CSE_CHECK_NON_MACRO)
configure_file("${CMAKE_ROOT}/Modules/CMakeConfigurableFile.in"
"${SOURCEFILE}" @ONLY)
if(NOT CMAKE_REQUIRED_QUIET)
message(CHECK_START "Looking for ${SYMBOL}")
endif()
try_compile(${VARIABLE}
${CMAKE_BINARY_DIR}
"${SOURCEFILE}"
COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
${CHECK_SYMBOL_EXISTS_LINK_OPTIONS}
${CHECK_SYMBOL_EXISTS_LIBS}
CMAKE_FLAGS
-DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_SYMBOL_EXISTS_FLAGS}
"${CMAKE_SYMBOL_EXISTS_INCLUDES}"
OUTPUT_VARIABLE OUTPUT)
if(${VARIABLE})
if(NOT CMAKE_REQUIRED_QUIET)
message(CHECK_PASS "found")
endif()
set(${VARIABLE} 1 CACHE INTERNAL "Have symbol ${SYMBOL}")
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
"Determining if the ${SYMBOL} "
"exist passed with the following output:\n"
"${OUTPUT}\nFile ${SOURCEFILE}:\n"
"${CMAKE_CONFIGURABLE_FILE_CONTENT}\n")
else()
if(NOT CMAKE_REQUIRED_QUIET)
message(CHECK_FAIL "not found")
endif()
set(${VARIABLE} "" CACHE INTERNAL "Have symbol ${SYMBOL}")
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"Determining if the ${SYMBOL} "
"exist failed with the following output:\n"
"${OUTPUT}\nFile ${SOURCEFILE}:\n"
"${CMAKE_CONFIGURABLE_FILE_CONTENT}\n")
endif()
unset(CMAKE_CONFIGURABLE_FILE_CONTENT)
endif()
endmacro()
cmake_policy(POP)
|
