[PATCH v2 kbuild for-next 1/2] makefiles: add config option to force all cc warnings to errors

[PATCH v2 kbuild for-next 1/2] makefiles: add config option to force all cc warnings to errors

[Jonathan Toppins]

Add a Kconfig option to force cc warnings to errors. For new
development it is recommended this setting be enabled as warnings
in the code will be quite obvious.

v2: * remove DOTs from Kconfig entries
    * reworded Kconfig to not imply suppressing cc warnings was
      acceptable
    * default option to 'n'

Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>
---
 Makefile          |    4 ++++
 lib/Kconfig.debug |   10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/Makefile b/Makefile
index dc2d91a..a69562a 100644
--- a/Makefile
+++ b/Makefile
@@ -764,6 +764,10 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH
 KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
 endif
 
+ifdef CONFIG_DEBUG_FORCE_CC_WARNINGS_TO_ERRORS
+KBUILD_CFLAGS += $(call cc-option, -Werror)
+endif
+
 # arch Makefile may override CC so keep this after arch Makefile is included
 NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
 CHECKFLAGS     += $(NOSTDINC_FLAGS)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 3e0289e..bbe2eed 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -347,6 +347,16 @@ config DEBUG_FORCE_WEAK_PER_CPU
 	  To ensure that generic code follows the above rules, this
 	  option forces all percpu variables to be defined as weak.
 
+config DEBUG_FORCE_CC_WARNINGS_TO_ERRORS
+	bool "Force cc warnings to errors"
+	help
+	  Simply enables the gcc compiler option -Werror for the entire
+	  build. This option is intended to be more in the developer's
+	  face and encourage effort of some kind to remove the
+	  compilation warning.
+
+	  If doing new development recommend setting to y.
+
 endmenu # "Compiler options"
 
 config MAGIC_SYSRQ
-- 
1.7.10.4

[PATCH v2 kbuild for-next 2/2] modpost: add Kconfig option to report warnings as errors

[Jonathan Toppins]

Add a Kconfig option to cause modpost to report warnings as errors.
This is a simplistic implementation in that modpost only reports the
first warning as an error and subsequent unreported warnings that will
kill the build may still exist.

v2: * removed DOTs from Kconfig entries

Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>
---
 lib/Kconfig.debug     |    9 +++++++++
 scripts/mod/modpost.c |    5 +++++
 2 files changed, 14 insertions(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index bbe2eed..94ee0c4 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -357,6 +357,15 @@ config DEBUG_FORCE_CC_WARNINGS_TO_ERRORS
 
 	  If doing new development recommend setting to y.
 
+config DEBUG_FORCE_MODPOST_WARNINGS_TO_ERRORS
+	bool "Force modpost warnings to errors"
+	help
+	  Force warnings generated by modpost to be reported as errors.
+	  Another build time setting to encourage some action be taken by
+	  the developer to fix the problem.
+
+	  If developing new code say y.
+
 endmenu # "Compiler options"
 
 config MAGIC_SYSRQ
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index d439856..d430eb6 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -70,6 +70,11 @@ PRINTF void warn(const char *fmt, ...)
 	va_start(arglist, fmt);
 	vfprintf(stderr, fmt, arglist);
 	va_end(arglist);
+
+#ifdef CONFIG_DEBUG_FORCE_MODPOST_WARNINGS_TO_ERRORS
+	fprintf(stderr, "modpost: warnings treated as errors.\n");
+	exit(1);
+#endif
 }
 
 PRINTF void merror(const char *fmt, ...)
-- 
1.7.10.4

Re: [PATCH v2 kbuild for-next 1/2] makefiles: add config option to force all cc warnings to errors

[Michal Marek]

On 2015-03-27 18:51, Jonathan Toppins wrote:
> Add a Kconfig option to force cc warnings to errors. For new
> development it is recommended this setting be enabled as warnings
> in the code will be quite obvious.

I don't want to add such kconfig option, because it will break
all{mod,yes}config for little gain. And there are warnings like the
preprocessor #warning or the use of a function marked as __deprecated --
these a basically TODOs and there is no point in failing the build. Test
builds can be done with KCFLAGS=-Werror or you can grep build logs.

Michal