cmake COMPILER_RT_HAS_WGNU_FLAG examples

Lewuathe/mlir-hello thirdparty/llvm-project/compiler-rt/cmake/config-ix.cmake :140 

check_cxx_compiler_flag("-Werror -Wgnu"                COMPILER_RT_HAS_WGNU_FLAG)

trailofbits/polytracker polytracker/src/compiler-rt/cmake/config-ix.cmake :104 

check_cxx_compiler_flag("-Werror -Wgnu"                COMPILER_RT_HAS_WGNU_FLAG)

CTSRD-CHERI/cheribsd contrib/subrepo-cheri-compiler-rt/cmake/config-ix.cmake :118 

check_cxx_compiler_flag("-Werror -Wgnu"                COMPILER_RT_HAS_WGNU_FLAG)