[U-Boot] [PATCH 1/4] Kbuild: support W=[N, ]err for passing '-Werror' to the compiler

[Daniel Schwierzeck]

Extend the Kbuild's W=N option with an optional 'err' value. This
will pass -Werror to the compiler to treat all warnings as errors.
This is useful to enforce a zero-warnings policy.

The 'err' value can also be combined with the numerical values
like this:

    make W=1
    make W=err
    make W=1,err

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
---

 scripts/Makefile.extrawarn | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 1d3a570594..d8d93b7fe1 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -48,9 +48,12 @@ warning-3 += -Wswitch-default
 warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
 warning-3 += $(call cc-option, -Wvla)
 
+warning-err := -Werror
+
 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)))
+warning += $(warning-$(findstring err, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
 
 ifeq ("$(strip $(warning))","")
         $(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
-- 
2.16.1