Building u-boot tools with clang as a host compiler e.g. on FreeBSD with `gmake HOSTCC=clang CONFIG_USE_PRIVATE_LIBGCC=y tools` leads to many warnings [1] for every compiler invocation since commit 598e2d33. Part of mentioned commit imports linux patches:
- kbuild: LLVMLinux: Adapt warnings for compilation with clang - kbuild: LLVMLinux: Add Kbuild support for building kernel with Clang
No version of clang supports the gcc fno-delete-null-pointer-checks though, but it is only passed to clang. Gcc does not have the clang specific Qunused-arguments for the target. Furthermore several warnings are disabled which aren't encountered in u-boot. Since such a build has worked for quite some time and works after removing these changes, just remove the clang specific handling to restore normal building with clang as hostcc.
[1] Actual warnings ------------------- GEN include/autoconf.mk.dep arm-freebsd-gcc: unrecognized option '-Qunused-arguments'
HOSTCC scripts/basic/fixdep clang: warning: argument unused during compilation: '-fno-delete-null-pointer-checks'
cc: Masahiro Yamada yamada.m@jp.panasonic.com Signed-off-by: Jeroen Hofstee jeroen@myspectrum.nl --- Makefile | 28 ---------------------------- 1 file changed, 28 deletions(-)
diff --git a/Makefile b/Makefile index e38fd2f..bde41aa 100644 --- a/Makefile +++ b/Makefile @@ -209,11 +209,6 @@ HOSTCXX = g++ HOSTCFLAGS = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer HOSTCXXFLAGS = -O2
-ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1) -HOSTCFLAGS += -Wno-unused-value -Wno-unused-parameter \ - -Wno-missing-field-initializers -fno-delete-null-pointer-checks -endif - ifeq ($(HOSTOS),cygwin) HOSTCFLAGS += -ansi endif @@ -320,15 +315,6 @@ endif
export quiet Q KBUILD_VERBOSE
-ifneq ($(CC),) -ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1) -COMPILER := clang -else -COMPILER := gcc -endif -export COMPILER -endif - # Look for make include files relative to root of kernel src MAKEFLAGS += --include-dir=$(srctree)
@@ -545,20 +531,6 @@ endif
KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
-ifeq ($(COMPILER),clang) -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) -KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,) -KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable) -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) -# Quiet clang warning: comparison of unsigned expression < 0 is always false -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) -# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the -# source of a reference will be _MergedGlobals and not on of the whitelisted names. -# See modpost pattern 2 -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) -endif - KBUILD_CFLAGS += -g # $(KBUILD_AFLAGS) sets -g, which causes gcc to pass a suitable -g<format> # option to the assembler.