CheckCCompilerFlag

Check once whether the C compiler supports a given flag.

check_c_compiler_flag

check_c_compiler_flag(<flag> <resultVar>)

Check once that the <flag> is accepted by the compiler without a diagnostic. The result is stored in the internal cache variable specified by <resultVar>, with boolean true for success and boolean false for failure.

true indicates only that the compiler did not issue a diagnostic message when given the flag. Whether the flag has any effect is beyond the scope of this module.

Internally, try_compile() is used to perform the check. If CMAKE_TRY_COMPILE_TARGET_TYPE is set to EXECUTABLE (default), the check compiles and links an executable program. If set to STATIC_LIBRARY, the check is compiled but not linked.

See also check_compiler_flag() for a more general command syntax.

The compile and link commands can be influenced by setting any of the following variables prior to calling check_c_compiler_flag(). Unknown flags in these variables can case a false negative result.

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

Added 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_LINK_DIRECTORIES

Added in version 3.31.

A ;-list of libraries search paths to pass to the linker (see try_compile() for further details).

CMAKE_REQUIRED_QUIET

Added in version 3.1.

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