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 current recipe is the use of string variables and lists to set compiler flags. Using string variables with the target_compile_options and target_link_libraries functions will result in a compiler and/or linker error. CMake will pass these options quoted, resulting in parsing errors. This justifies the need to express these options in terms of lists and the ensuing string manipulations, to replace spaces in string variables with semicolons. We recall, in fact, that lists in CMake are semicolon-separated strings.