CheckCCompilerFlag

Check whether the C compiler supports a given flag.

check_c_compiler_flag

check_c_compiler_flag(<flag> <resultVar>)

Check that the <flag> is accepted by the compiler without a diagnostic. Stores the result in an internal cache entry named <resultVar>.

A positive result from this check indicates only that the compiler did not issue a diagnostic message when given the flag. Whether the flag has any effect or even a specific one is beyond the scope of this module.

The check is only performed once, with the result cached in the variable named by <resultVar>. Every subsequent CMake run will reuse 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.

The compile and link commands can be influenced by setting any of the following variables prior to calling check_c_compiler_flag()

CMAKE_REQUIRED_FLAGS

String of additional flags to pass to the compiler. The string must be space-delimited--a ;-list will not work. The contents of CMAKE_<LANG>_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--the contents of the INCLUDE_DIRECTORIES directory property will be ignored.

CMAKE_REQUIRED_LINK_OPTIONS

New in version 3.14.

A ;-list of options to add to the link command (see try_compile() for further details).

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

New in version 3.1.

If this variable evaluates to a boolean true value, all status messages associated with the check will be suppressed.