Merge 3fe617ccaf ("Enable '-Werror' by default for all kernel builds") into android-mainline

Steps on the way to 5.15-rc1

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I0cb711ea7aab52e2670192f1a03ca9fbe9d4c166

Makefile

@@ -801,6 +801,9 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
 
 KBUILD_CFLAGS += $(stackp-flags-y)
 
+KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror
+KBUILD_CFLAGS += $(KBUILD_CFLAGS-y)
+
 ifdef CONFIG_CC_IS_CLANG
 KBUILD_CPPFLAGS += -Qunused-arguments
 # The kernel builds with '-std=gnu89' so use of GNU extensions is acceptable.

init/Kconfig

@@ -137,6 +137,20 @@ config COMPILE_TEST
 	  here. If you are a user/distributor, say N here to exclude useless
 	  drivers to be distributed.
 
+config WERROR
+	bool "Compile the kernel with warnings as errors"
+	default y
+	help
+	  A kernel build should not cause any compiler warnings, and this
+	  enables the '-Werror' flag to enforce that rule by default.
+
+	  However, if you have a new (or very old) compiler with odd and
+	  unusual warnings, or you have some architecture with problems,
+	  you may need to disable this config option in order to
+	  successfully build the kernel.
+
+	  If in doubt, say Y.
+
 config UAPI_HEADER_TEST
 	bool "Compile test UAPI headers"
 	depends on HEADERS_INSTALL && CC_CAN_LINK