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perf build: Allow nested externs to enable BUILD_BUG() usage 

Currently BUILD_BUG() macro is expanded to smth like the following:

   do {
           extern void __compiletime_assert_0(void)
                   __attribute__((error("BUILD_BUG failed")));
           if (!(!(1)))
                   __compiletime_assert_0();
   } while (0);

If used in a function body this obviously would produce build errors
with -Wnested-externs and -Werror.

To enable BUILD_BUG() usage in tools/arch/x86/lib/insn.c which perf
includes in intel-pt-decoder, build perf without -Wnested-externs.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Stephen Rothwell <sfr@canb.auug.org.au> # build tested
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/patch-1.thread-251403.git-2514037e9477.your-ad-here.call-01602244460-ext-7088@work.hours
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Vasily Gorbik 2020-10-09 14:25:23 +02:00 committed by Arnaldo Carvalho de Melo
parent f3013f7ed4
commit 6cf4ecf5c5
1 changed files with 1 additions and 1 deletions
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2
tools/perf/Makefile.config
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@ -16,7 +16,7 @@ $(shell printf "" > $(OUTPUT).config-detected)
detected = $(shell echo "$(1)=y" >> $(OUTPUT).config-detected)
detected_var = $(shell echo "$(1)=$($(1))" >> $(OUTPUT).config-detected)
CFLAGS := $(EXTRA_CFLAGS) $(EXTRA_WARNINGS)
CFLAGS := $(EXTRA_CFLAGS) $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))
include $(srctree)/tools/scripts/Makefile.arch