[PATCH] kbuild: support W=c and W=e shorthands for Kconfig

[Masahiro Yamada <masahiroy@kernel.org>]

KCONFIG_WARN_UNKNOWN_SYMBOLS=1 and KCONFIG_WERROR=1 are descriptive
and suitable in scripting, but it is tedious to type them from the
command line.

Associate them with KBUILD_EXTRA_WARN (and the W= shorthand).

Support a new letter 'c' for KBUILD_EXTRA_WARN to enable extra checks
in Kconfig. You can still manage compiler warnings (W=1) and Kconfig
warnings (W=c) independently.

Reuse the letter 'e' to turn Kconfig warnings into errors.

As usual, you can combine multiple letters in KCONFIG_EXTRA_WARN.

  $ KCONFIG_WARN_UNKNOWN_SYMBOLS=1 KCONFIG_WERROR=1 make defconfig

can be shortened to:

  $ KBUILD_EXTRA_WARN=ce make defconfig

or, even shorter:

  $ make W=ce defconfig

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 Makefile                   | 10 ++++++++++
 scripts/Makefile.extrawarn |  9 ---------
 scripts/kconfig/Makefile   |  8 ++++++++
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index f128a1a1b1a0..91947f722b77 100644
--- a/Makefile
+++ b/Makefile
@@ -155,6 +155,15 @@ endif
 
 export KBUILD_EXTMOD
 
+# backward compatibility
+KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
+
+ifeq ("$(origin W)", "command line")
+  KBUILD_EXTRA_WARN := $(W)
+endif
+
+export KBUILD_EXTRA_WARN
+
 # Kbuild will save output files in the current working directory.
 # This does not need to match to the root of the kernel source tree.
 #
@@ -1659,6 +1668,7 @@ help:
 	@echo  '		1: warnings which may be relevant and do not occur too often'
 	@echo  '		2: warnings which occur quite often but may still be relevant'
 	@echo  '		3: more obscure warnings, can most likely be ignored'
+	@echo  '		c: extra checks in the configuration stage (Kconfig)'
 	@echo  '		e: warnings are being treated as errors'
 	@echo  '		Multiple levels can be combined with W=12 or W=123'
 	@$(if $(dtstree), \
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 2fe6f2828d37..3f94915fab37 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -80,15 +80,6 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
 # Warn if there is an enum types mismatch
 KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
 
-# backward compatibility
-KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
-
-ifeq ("$(origin W)", "command line")
-  KBUILD_EXTRA_WARN := $(W)
-endif
-
-export KBUILD_EXTRA_WARN
-
 #
 # W=1 - warnings which may be relevant and do not occur too often
 #
diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
index 4eee155121a8..322c061b464d 100644
--- a/scripts/kconfig/Makefile
+++ b/scripts/kconfig/Makefile
@@ -27,6 +27,14 @@ KCONFIG_DEFCONFIG_LIST += \
 endif
 KCONFIG_DEFCONFIG_LIST += arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)
 
+ifneq ($(findstring c, $(KBUILD_EXTRA_WARN)),)
+export KCONFIG_WARN_UNKNOWN_SYMBOLS=1
+endif
+
+ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
+export KCONFIG_WERROR=1
+endif
+
 # We need this, in case the user has it in its environment
 unexport CONFIG_
 
-- 
2.40.1