File llvm-remove-clang-only-flags.patch of Package llvm9.15568

Index: llvm-8.0.0rc3.src/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm-8.0.0rc3.src.orig/cmake/modules/HandleLLVMOptions.cmake
+++ llvm-8.0.0rc3.src/cmake/modules/HandleLLVMOptions.cmake
@@ -413,8 +413,6 @@ if( MSVC )
 elseif( LLVM_COMPILER_IS_GCC_COMPATIBLE )
   append_if(LLVM_ENABLE_WERROR "-Werror" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
   append_if(LLVM_ENABLE_WERROR "-Wno-error" CMAKE_REQUIRED_FLAGS)
-  add_flag_if_supported("-Werror=date-time" WERROR_DATE_TIME)
-  add_flag_if_supported("-Werror=unguarded-availability-new" WERROR_UNGUARDED_AVAILABILITY_NEW)
   check_cxx_compiler_flag("-std=${LLVM_CXX_STD}" CXX_SUPPORTS_CXX_STD)
   if (CXX_SUPPORTS_CXX_STD)
    if (CYGWIN OR MINGW)
@@ -586,7 +584,6 @@ if (LLVM_ENABLE_WARNINGS AND (LLVM_COMPI
   endif()
 
   add_flag_if_supported("-Wimplicit-fallthrough" IMPLICIT_FALLTHROUGH_FLAG)
-  add_flag_if_supported("-Wcovered-switch-default" COVERED_SWITCH_DEFAULT_FLAG)
   append_if(USE_NO_UNINITIALIZED "-Wno-uninitialized" CMAKE_CXX_FLAGS)
   append_if(USE_NO_MAYBE_UNINITIALIZED "-Wno-maybe-uninitialized" CMAKE_CXX_FLAGS)