[CMake][llvm] avoid conflict w/ (and use when available) new builtin check_linker_flag

[radford]

Summary

Match the API for the new check_linker_flag and use it directly when available, leaving the old code as a fallback.

[JDevlieghere]

llvm/cmake/modules/HandleLLVMOptions.cmake

892

I don't think this is CMake's check_linker_flag but rather the one from CheckLinkerFlag.cmake. Given that this requires CMake 3.18 and we support older versios, we will continue to need the wrapper until that gets bumped. I think we should probably update the function and rename it to avoid the name collision (and maybe implement it in terms of check_linker_flag(CXX ... when the CMake version is >=3.18.

[radford]

[CMake][llvm] The first argument to check_linker_flag is the language

Match the API for the new check_linker_flag and use it directly when
available, leaving the old code as a fallback.

[JDevlieghere]

LGTM. Thanks!

llvm/cmake/modules/HandleLLVMOptions.cmake

if (UNIX AND
      (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND
       NOT (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9))))
   append("-fdiagnostics-color" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 endif()
 
 # lld doesn't print colored diagnostics when invoked from Ninja
 if (UNIX AND CMAKE_GENERATOR STREQUAL "Ninja")
   include(CheckLinkerFlag)
-  check_linker_flag("-Wl,--color-diagnostics" LINKER_SUPPORTS_COLOR_DIAGNOSTICS)
+  check_linker_flag(CXX "-Wl,--color-diagnostics" LINKER_SUPPORTS_COLOR_DIAGNOSTICS)
   append_if(LINKER_SUPPORTS_COLOR_DIAGNOSTICS "-Wl,--color-diagnostics"
     CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
 endif()
 
 # Add flags for add_dead_strip().
 # FIXME: With MSVS, consider compiling with /Gy and linking with /OPT:REF?
 # But MinSizeRel seems to add that automatically, so maybe disable these
 # flags instead if LLVM_NO_DEAD_STRIP is set.