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
>