[compiler-rt] [compiler-rt][builtins] Fix detection of warnings flags (PR #125602)

[Alexander Richardson via llvm-commits]

https://github.com/arichardson created https://github.com/llvm/llvm-project/pull/125602

It appears that these checks report true without -Werror since they only
trigger a -Wunknown-warning-option that does not fail the check.
See also commit bfa6444a (#83779)

Fixes: https://github.com/llvm/llvm-project/issues/72413


>From c1a806aa1457fa82fe2c3ca501b14572e42b03fa Mon Sep 17 00:00:00 2001
From: Alex Richardson <alexrichardson at google.com>
Date: Mon, 3 Feb 2025 16:10:38 -0800
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.6-beta.1
---
 compiler-rt/cmake/builtin-config-ix.cmake | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler-rt/cmake/builtin-config-ix.cmake b/compiler-rt/cmake/builtin-config-ix.cmake
index b1bde47ec8555f..b52de9c978eacf 100644
--- a/compiler-rt/cmake/builtin-config-ix.cmake
+++ b/compiler-rt/cmake/builtin-config-ix.cmake
@@ -18,12 +18,12 @@ builtin_check_c_compiler_flag(-fno-lto              COMPILER_RT_HAS_FNO_LTO_FLAG
 builtin_check_c_compiler_flag(-fno-profile-generate COMPILER_RT_HAS_FNO_PROFILE_GENERATE_FLAG)
 builtin_check_c_compiler_flag(-fno-profile-instr-generate COMPILER_RT_HAS_FNO_PROFILE_INSTR_GENERATE_FLAG)
 builtin_check_c_compiler_flag(-fno-profile-instr-use COMPILER_RT_HAS_FNO_PROFILE_INSTR_USE_FLAG)
-builtin_check_c_compiler_flag(-Wno-pedantic         COMPILER_RT_HAS_WNO_PEDANTIC)
+builtin_check_c_compiler_flag("-Werror -Wno-pedantic" COMPILER_RT_HAS_WNO_PEDANTIC)
 builtin_check_c_compiler_flag(-nogpulib             COMPILER_RT_HAS_NOGPULIB_FLAG)
 builtin_check_c_compiler_flag(-flto                 COMPILER_RT_HAS_FLTO_FLAG)
 builtin_check_c_compiler_flag(-fconvergent-functions COMPILER_RT_HAS_FCONVERGENT_FUNCTIONS_FLAG)
 builtin_check_c_compiler_flag("-Xclang -mcode-object-version=none" COMPILER_RT_HAS_CODE_OBJECT_VERSION_FLAG)
-builtin_check_c_compiler_flag(-Wbuiltin-declaration-mismatch COMPILER_RT_HAS_WBUILTIN_DECLARATION_MISMATCH_FLAG)
+builtin_check_c_compiler_flag("-Werror -Wbuiltin-declaration-mismatch" COMPILER_RT_HAS_WBUILTIN_DECLARATION_MISMATCH_FLAG)
 builtin_check_c_compiler_flag(/Zl COMPILER_RT_HAS_ZL_FLAG)
 
 builtin_check_c_compiler_source(COMPILER_RT_HAS_ATOMIC_KEYWORD