[PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

[behanw@converseincode.com]

From: Behan Webster <behanw@converseincode.com>

clang has more warnings enabled by default. Turn them off unless W is set.
This patch fixes a logic bug where warnings in clang were disabled when W was set.

Signed-off-by: Behan Webster <behanw@converseincode.com>
Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de>
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Cc: mmarek@suse.cz
Cc: bp@alien8.de
---
 Makefile                   |  1 +
 scripts/Makefile.extrawarn | 22 ++++++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index f6a7794..f343e17 100644
--- a/Makefile
+++ b/Makefile
@@ -668,6 +668,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # 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,)
+KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
 else
 
 # This warning generated too much noise in a regular build.
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 6564350..b5b0751 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -26,16 +26,6 @@ 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)
 
-# Clang
-warning-1 += $(call cc-disable-warning, initializer-overrides)
-warning-1 += $(call cc-disable-warning, unused-value)
-warning-1 += $(call cc-disable-warning, format)
-warning-1 += $(call cc-disable-warning, unknown-warning-option)
-warning-1 += $(call cc-disable-warning, sign-compare)
-warning-1 += $(call cc-disable-warning, format-zero-length)
-warning-1 += $(call cc-disable-warning, uninitialized)
-warning-1 += $(call cc-option, -fcatch-undefined-behavior)
-
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
 warning-2 += -Wdisabled-optimization
@@ -55,6 +45,18 @@ warning-3 += -Wswitch-default
 warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
 warning-3 += $(call cc-option, -Wvla)
 
+ifeq ($(COMPILER),clang)
+ifndef $(W)
+KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
+KBUILD_CFLAGS += $(call cc-disable-warning, format)
+KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
+KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
+KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
+endif
+endif
+
 warning := $(warning-$(findstring 1, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
 warning += $(warning-$(findstring 2, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
 warning += $(warning-$(findstring 3, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
-- 
1.9.1