Re: [dpdk-dev] [PATCH] Make -Werror optional

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 12 Feb 2015 13:13:22 +0200
Panu Matilainen <pmatilai@redhat.com> wrote:

> This adds new CONFIG_RTE_ERROR_ON_WARNING config option to enable
> fail-on-warning compile behavior, defaulting to off.
> 
> Failing build on warnings is a useful developer tool but its bad
> for release tarballs which can and do get built with newer
> compilers than what was used/available during development. Compilers
> routinely add new warnings so code which built silently with cc X
> might no longer do so with X+1. This doesn't make the existing code
> any more buggier and failing the build in this case does not help
> not help improve code quality of an already released version either.
> ---
>  config/common_bsdapp           | 1 +
>  config/common_linuxapp         | 1 +
>  mk/toolchain/clang/rte.vars.mk | 5 ++++-
>  mk/toolchain/gcc/rte.vars.mk   | 5 ++++-
>  mk/toolchain/icc/rte.vars.mk   | 6 +++++-
>  5 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/config/common_bsdapp b/config/common_bsdapp
> index 57bacb8..a5687b3 100644
> --- a/config/common_bsdapp
> +++ b/config/common_bsdapp
> @@ -362,6 +362,7 @@ CONFIG_RTE_KNI_VHOST_DEBUG_TX=n
>  # Enable warning directives
>  #
>  CONFIG_RTE_INSECURE_FUNCTION_WARNING=n
> +CONFIG_RTE_ERROR_ON_WARNING=n
>  
>  #
>  # Compile the test application
> diff --git a/config/common_linuxapp b/config/common_linuxapp
> index d428f84..0762f99 100644
> --- a/config/common_linuxapp
> +++ b/config/common_linuxapp
> @@ -383,6 +383,7 @@ CONFIG_RTE_LIBRTE_XEN_DOM0=n
>  # Enable warning directives
>  #
>  CONFIG_RTE_INSECURE_FUNCTION_WARNING=n
> +CONFIG_RTE_ERROR_ON_WARNING=n
>  
>  #
>  # Compile the test application
> diff --git a/mk/toolchain/clang/rte.vars.mk b/mk/toolchain/clang/rte.vars.mk
> index 40cb389..12726e7 100644
> --- a/mk/toolchain/clang/rte.vars.mk
> +++ b/mk/toolchain/clang/rte.vars.mk
> @@ -63,11 +63,14 @@ TOOLCHAIN_ASFLAGS =
>  TOOLCHAIN_CFLAGS =
>  TOOLCHAIN_LDFLAGS =
>  
> -WERROR_FLAGS := -W -Wall -Werror -Wstrict-prototypes -Wmissing-prototypes
> +WERROR_FLAGS := -W -Wall -Wstrict-prototypes -Wmissing-prototypes
>  WERROR_FLAGS += -Wmissing-declarations -Wold-style-definition -Wpointer-arith
>  WERROR_FLAGS += -Wnested-externs -Wcast-qual
>  WERROR_FLAGS += -Wformat-nonliteral -Wformat-security
>  WERROR_FLAGS += -Wundef -Wwrite-strings
> +ifeq ($(CONFIG_RTE_ERROR_ON_WARNING),y)
> +WERROR_FLAGS += -Werror
> +endif
>  
>  # process cpu flags
>  include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk
> diff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk
> index 88f235c..bbd3c85 100644
> --- a/mk/toolchain/gcc/rte.vars.mk
> +++ b/mk/toolchain/gcc/rte.vars.mk
> @@ -71,11 +71,14 @@ ifeq (,$(findstring -O0,$(EXTRA_CFLAGS)))
>  endif
>  endif
>  
> -WERROR_FLAGS := -W -Wall -Werror -Wstrict-prototypes -Wmissing-prototypes
> +WERROR_FLAGS := -W -Wall -Wstrict-prototypes -Wmissing-prototypes
>  WERROR_FLAGS += -Wmissing-declarations -Wold-style-definition -Wpointer-arith
>  WERROR_FLAGS += -Wcast-align -Wnested-externs -Wcast-qual
>  WERROR_FLAGS += -Wformat-nonliteral -Wformat-security
>  WERROR_FLAGS += -Wundef -Wwrite-strings
> +ifeq ($(CONFIG_RTE_ERROR_ON_WARNING),y)
> +WERROR_FLAGS += -Werror
> +endif
>  
>  # process cpu flags
>  include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk
> diff --git a/mk/toolchain/icc/rte.vars.mk b/mk/toolchain/icc/rte.vars.mk
> index e39d710..652cca8 100644
> --- a/mk/toolchain/icc/rte.vars.mk
> +++ b/mk/toolchain/icc/rte.vars.mk
> @@ -69,8 +69,12 @@ TOOLCHAIN_ASFLAGS =
>  #   error #13368: loop was not vectorized with "vector always assert"
>  #   error #15527: loop was not vectorized: function call to fprintf cannot be vectorize
>  #                   was declared "deprecated"
> -WERROR_FLAGS := -Wall -Werror-all -w2 -diag-disable 271 -diag-warning 1478
> +WERROR_FLAGS := -Wall -w2 -diag-disable 271 -diag-warning 1478
>  WERROR_FLAGS += -diag-disable 13368 -diag-disable 15527
> +ifeq ($(CONFIG_RTE_ERROR_ON_WARNING),y)
> +WERROR_FLAGS += -Werror-all
> +endif
> +
>  
>  # process cpu flags
>  include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk

The -Werror is a real feature. Having dealt with legacy code where
there are lots of bugs which were already warnings being ignored, having
a big hard stop when errors are found is really good.

The default should be on but I understand why you may want to turn it
off, but it should require some effort to do.