CheckCSourceCompiles

Check if given C source compiles and links into an executable.

check_c_source_compiles
check_c_source_compiles(code resultVar [FAIL_REGEX regex1 [regex2...]])

Check that the source supplied in code can be compiled as a C source file and linked as an executable (so it must contain at least a main() function). The result will be stored in the internal cache variable specified by resultVar, with a boolean true value for success and boolean false for failure. If FAIL_REGEX is provided, then failure is determined by checking if anything in the output matches any of the specified regular expressions.

The underlying check is performed by the try_compile() command. The compile and link commands can be influenced by setting any of the following variables prior to calling check_c_source_compiles():

CMAKE_REQUIRED_FLAGS
Additional flags to pass to the compiler. Note that the contents of CMAKE_C_FLAGS and its associated configuration-specific variable are automatically added to the compiler command before the contents of CMAKE_REQUIRED_FLAGS.
CMAKE_REQUIRED_DEFINITIONS
A ;-list of compiler definitions of the form -DFOO or -DFOO=bar. A definition for the name specified by resultVar will also be added automatically.
CMAKE_REQUIRED_INCLUDES
A ;-list of header search paths to pass to the compiler. These will be the only header search paths used by try_compile(), i.e. the contents of the INCLUDE_DIRECTORIES directory property will be ignored.
CMAKE_REQUIRED_LIBRARIES
A ;-list of libraries to add to the link command. These can be the name of system libraries or they can be Imported Targets (see try_compile() for further details).
CMAKE_REQUIRED_QUIET
If this variable evaluates to a boolean true value, all status messages associated with the check will be suppressed.

The check is only performed once, with the result cached in the variable named by resultVar. Every subsequent CMake run will re-use this cached value rather than performing the check again, even if the code changes. In order to force the check to be re-evaluated, the variable named by resultVar must be manually removed from the cache.