kbuild: remove redundant extra warning flags

There is no point in turning individual options off and then on again, or
vice versa, as the last one always wins.  Now that -Wextra always gets
passed first, remove all the redundant lines about warnings that are
implied by either -Wall or -Wextra, and keep only the last one that
disables it in some configurations.

This should not have any effect but keep the Makefile more readable and
the command line shorter.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nicolas Schier <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: arndb

scripts/Makefile.extrawarn

@@ -37,11 +37,6 @@ else
 KBUILD_CFLAGS += -Wno-main
 endif
 
-# These warnings generated too much noise in a regular build.
-# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
-
 # These result in bogus false positives
 KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
 
@@ -90,16 +85,9 @@ KBUILD_CFLAGS += -Wunused
 #
 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
 
-KBUILD_CFLAGS += $(call cc-option, -Wrestrict)
 KBUILD_CFLAGS += -Wmissing-format-attribute
-KBUILD_CFLAGS += -Wold-style-definition
 KBUILD_CFLAGS += -Wmissing-include-dirs
-KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
 KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
-KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
-KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow)
-KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation)
-KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
 
 KBUILD_CPPFLAGS += -Wundef
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
@@ -150,9 +138,6 @@ ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
 KBUILD_CFLAGS += -Wdisabled-optimization
 KBUILD_CFLAGS += -Wshadow
 KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
-KBUILD_CFLAGS += -Wmissing-field-initializers
-KBUILD_CFLAGS += -Wtype-limits
-KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
 KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
 
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2