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[PATCH] kbuild: Demote 'sign-compare' warning to W=2

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  [PATCH] kbuild: Demote 'sign-compare' warning to W=2 Lee Jones <lee.jones@linaro.org> - 2016-01-12 14:40 +0100
    Re: [PATCH] kbuild: Demote 'sign-compare' warning to W=2 Arnd Bergmann <arnd@arndb.de> - 2016-01-12 15:10 +0100

#1307401 — [PATCH] kbuild: Demote 'sign-compare' warning to W=2

Ideally, a kernel compile with W=1 enabled should complete cleanly;
however, when we run one currently we are presented with ~25k warnings.
'sign-compare' accounts for ~22k of those ~25k.

In this patch we're demoting 'sign-compare' warnings to W=2, with a view
to fixing the remaining 3k W=1 warnings required for a clean build.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 scripts/Makefile.extrawarn | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 4efedcb..f9e47a7 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -25,6 +25,7 @@ warning-1 += -Wold-style-definition
 warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
+warning-1 += $(call cc-disable-warning, sign-compare)
 
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
@@ -33,6 +34,7 @@ warning-2 += -Wnested-externs
 warning-2 += -Wshadow
 warning-2 += $(call cc-option, -Wlogical-op)
 warning-2 += $(call cc-option, -Wmissing-field-initializers)
+warning-2 += $(call cc-option, -Wsign-compare)
 
 warning-3 := -Wbad-function-cast
 warning-3 += -Wcast-qual
-- 
1.9.1

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#1307446

On Tuesday 12 January 2016 13:31:59 Lee Jones wrote:
> Ideally, a kernel compile with W=1 enabled should complete cleanly;
> however, when we run one currently we are presented with ~25k warnings.
> 'sign-compare' accounts for ~22k of those ~25k.
> 
> In this patch we're demoting 'sign-compare' warnings to W=2, with a view
> to fixing the remaining 3k W=1 warnings required for a clean build.
> 
> Cc: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> 

As per our discussion, I'd add that this was inadvertedly introduced
by Behan when he moved the clang specific warnings into an ifdef block
and did not notice that -Wsign-compare was interpreted by both gcc
and clang.

Earlier, it was introduced in just the same way by Jan-Simon as part
of 3d3d6b847420 ("kbuild: LLVMLinux: Adapt warnings for compilation with clang").

The new patch looks good to me, please add

Acked-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 26ea6bb1fef0 ("kbuild, LLVMLinux: Supress warnings unless W=1-3")

I've started looking into building the kernel with clang, and will likely
follow up with further unrelated changes to the list, as clang-3.9
seems to generate a couple of extra warnings we want to suppress.

	Arnd

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