CheckCCompilerFlag

Check whether the C compiler supports a given flag.

check_c_compiler_flag

check_c_compiler_flag(<flag> <var>)

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

This command temporarily sets the CMAKE_REQUIRED_DEFINITIONS variable and calls the check_c_source_compiles macro from the CheckCSourceCompiles module. See documentation of that module for a listing of variables that can otherwise modify the build.

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.