Maybe having the check last would be cleaner. 

diff --git a/BaseTools/Source/C/DevicePath/GNUmakefile b/BaseTools/Source/C/DevicePath/GNUmakefile
index c217674345b1..17f213879e82 100644
--- a/BaseTools/Source/C/DevicePath/GNUmakefile
+++ b/BaseTools/Source/C/DevicePath/GNUmakefile
@@ -16,10 +16,12 @@ include $(MAKEROOT)/Makefiles/app.makefile
 GCCVERSION = $(shell gcc -dumpversion | awk -F'.' '{print $$1}')
 ifneq ("$(GCCVERSION)", "5")
 ifneq ($(CXX), llvm)
+ifneq ($(DARWIN),Darwin)
 # gcc 12 trips over device path handling
 BUILD_CFLAGS += -Wno-error=stringop-overflow
 endif
 endif
+endif
 
 LIBS = -lCommon
 ifeq ($(CYGWIN), CYGWIN)


Thanks,

Andrew Fish

> On Aug 25, 2022, at 10:45 AM, Andrew Fish via groups.io <afish=apple.com@groups.io> wrote:
> 
> Rebecca,
> 
> FYI /usr/bin/gcc has been a redirector into clang for a lot of years. 
> 
> The build picks different default sets of complier flags based on build type. There is already code that assumes gcc == clang here [1]
> 
> I think the issue is the check that is wrapping "BUILD_CFLAGS += -Wno-error=stringop-overflow”. It needs to skip the check on macOS. 
> 
> diff --git a/BaseTools/Source/C/DevicePath/GNUmakefile b/BaseTools/Source/C/DevicePath/GNUmakefile
> index c217674345b1..f3c9739617f2 100644
> --- a/BaseTools/Source/C/DevicePath/GNUmakefile
> +++ b/BaseTools/Source/C/DevicePath/GNUmakefile
> @@ -14,12 +14,14 @@ OBJECTS = DevicePath.o UefiDevicePathLib.o DevicePathFromText.o  DevicePathUtili
>  include $(MAKEROOT)/Makefiles/app.makefile
>  
>  GCCVERSION = $(shell gcc -dumpversion | awk -F'.' '{print $$1}')
> +ifneq ($(DARWIN),Darwin)
>  ifneq ("$(GCCVERSION)", "5")
>  ifneq ($(CXX), llvm)
>  # gcc 12 trips over device path handling
>  BUILD_CFLAGS += -Wno-error=stringop-overflow
>  endif
>  endif
> +endif
>  
>  LIBS = -lCommon
>  ifeq ($(CYGWIN), CYGWIN)
> 
> 
> [1] https://github.com/tianocore/edk2/blob/master/BaseTools/Source/C/Makefiles/header.makefile#L83
> 
> Thanks,
> 
> Andrew Fish
> 
>> On Aug 25, 2022, at 9:20 AM, Rebecca Cran <rebecca@bsdio.com> wrote:
>> 
>> BaseTools no longer builds on macOS (12.5.1, Monterey), because 'gcc' in /usr/bin is really clang.
>> 
>> I tried installing gcc 12 from Homebrew, but the build then failed saying it couldn't find _stdio.h.
>> 
>> It appears the breakage might have been introduced in this commit back in March:
>> 
>> commit 22130dcd98b4d4b76ac8d922adb4a2dbc86fa52c
>> Author: Gerd Hoffmann <kraxel@redhat.com>
>> Date:   Thu Mar 24 20:04:36 2022 +0800
>> 
>>     Basetools: turn off gcc12 warning
>> 
>> Running "make -C BaseTools" produces the following error:
>> 
>> 
>> /Library/Developer/CommandLineTools/usr/bin/make -C DevicePath
>> gcc  -c  -I .. -I ../Include/Common -I ../Include/ -I ../Include/IndustryStandard -I ../Common/ -I .. -I . -I ../Include/X64/ -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations -Wno-self-assign -Wno-unused-result -nostdlib -g -O2  -Wno-error=stringop-overflow DevicePath.c -o DevicePath.o
>> error: unknown warning option '-Werror=stringop-overflow'; did you mean '-Werror=shift-overflow'? [-Werror,-Wunknown-warning-option]
>> make[2]: *** [DevicePath.o] Error 1
>> make[1]: *** [DevicePath] Error 2
>> make: *** [Source/C] Error 2
>> 
>> 
>> bcran@procan edk2 % gcc -v
>> Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
>> Apple clang version 12.0.5 (clang-1205.0.22.9)
>> Target: x86_64-apple-darwin21.6.0
>> Thread model: posix
>> InstalledDir: /Library/Developer/CommandLineTools/usr/bin
>> 
>> bcran@procan edk2 % uname -a
>> Darwin procan.int.bsdio.com 21.6.0 Darwin Kernel Version 21.6.0: Wed Aug 10 14:25:27 PDT 2022; root:xnu-8020.141.5~2/RELEASE_X86_64 x86_64
>> 
>> -- 
>> Rebecca Cran
>> 
> 
>