The check_<lang>_compiler_flag functions are simply wrappers around the check_<lang>_source_compiles function, which we discussed in the previous recipe. These wrappers provide a shortcut for the common use case where it is not important to check whether a specific code snippet compiles, but whether the compiler understands a set of flags.
Compiler flags for sanitizers are a special case, in that they also need to be passed on to the linker. To achieve this with the check_<lang>_compiler_flag functions, we need to set the CMAKE_REQUIRED_FLAGS variable prior to the call. The flags passed as the first argument would otherwise only be used in the call to the compiler, resulting in a false negative.
One more point to notice in the ...
