Re: linux-next: build warning after merge of the kbuild tree

[Stephen Rothwell]

Hi Dave,

On Sun, 1 May 2011 22:24:18 -0400 Dave Jones <davej@xxxxxxxxxx> wrote:
>
> Which version of the patch got merged ? This should be guarded by cc-option checks.

It looks right to me (that's why I wrote "though I don't see why") but
empirically we have a problem.

This is what is in -next today:

From: Dave Jones <davej@xxxxxxxxxx>
Date: Thu, 21 Apr 2011 17:28:13 -0400
Subject: [PATCH] kbuild: Disable -Wunused-but-set-variable for gcc 4.6.0

Disable the new -Wunused-but-set-variable that was added in gcc 4.6.0
It produces more false positives than useful warnings.

This can still be enabled using W=1

Signed-off-by: Dave Jones <davej@xxxxxxxxxx>
Acked-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Tested-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Signed-off-by: Michal Marek <mmarek@xxxxxxx>
---
 Makefile               |    4 ++++
 scripts/Makefile.build |    1 +
 2 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/Makefile b/Makefile
index e509cc7..4527dc2 100644
--- a/Makefile
+++ b/Makefile
@@ -567,6 +567,10 @@ ifndef CONFIG_CC_STACKPROTECTOR
 KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
 endif
 
+# This warning generated too much noise in a regular build.
+# Use make W=1 to enable this warning (see scripts/Makefile.build)
+KBUILD_CFLAGS += $(call cc-option, -Wno-unused-but-set-variable)
+
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 else
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9c0c481..9fb19c0 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -66,6 +66,7 @@ warning-1 += -Wmissing-format-attribute
 warning-1 += -Wmissing-prototypes
 warning-1 += -Wold-style-definition
 warning-1 += $(call cc-option, -Wmissing-include-dirs)
+warning-1 += $(call cc-option, -Wunused-but-set-variable)
 
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
-- 
1.7.4.4

-- 
Cheers,
Stephen Rothwell                    sfr@xxxxxxxxxxxxxxxx
http://www.canb.auug.org.au/~sfr/
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