Re: [PATCH v2 2/4] configure: Enforce gnu99 C language standard

[Javier Martinez Canillas]

On 4/3/20 2:45 PM, Daniel Kiper wrote:
> Commit d5a32255d (misc: Make grub_strtol() "end" pointers have safer
> const qualifiers) introduced "restrict" keyword into some functions
> definitions. This keyword was introduced in C99 standard. However, some
> compilers by default may use C89 or something different. This behavior
> leads to the breakage during builds when c89 or gnu89 is in force. So,
> let's enforce gnu99 C language standard for all compilers. This way
> a bit random build issue will be fixed and the GRUB source will be
> build consistently regardless of type and version of the compiler.
> 
> It was decided to use gnu99 C language standard because it fixes the
> issue mentioned above and also provides some useful extensions which are
> used here and there in the GRUB source. Potentially we can use gnu11 too.
> However, this may reduce pool of older compilers which can be used to
> build the GRUB. So, let's live with gnu99 until we do not discover that
> we strongly require a feature from newer C standard.
> 
> Signed-off-by: Daniel Kiper <address@hidden>
> ---
> v2 - suggestions/fixes:
>    - unconditionally enforce gnu99 C language standard
>      (suggested by Leif Lindholm).
> ---
>  configure.ac | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index b2576b013..fc74ee800 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -80,6 +80,10 @@ if test "x$TARGET_CFLAGS" = x; then
>    TARGET_CFLAGS=-Os
>  fi
> 

I would add a comment here explaining why gnu99 is enforced.
 
> +BUILD_CFLAGS="-std=gnu99 $BUILD_CFLAGS"
> +HOST_CFLAGS="-std=gnu99 $HOST_CFLAGS"
> +TARGET_CFLAGS="-std=gnu99 $TARGET_CFLAGS"
> +

Do you want to allow distros to override the -std option or do you want to
always force to use gnu99? If the latter then I think instead it should be:

BUILD_CFLAGS="$BUILD_CFLAGS -std=gnu99"
HOST_CFLAGS="$HOST_CFLAGS -std=gnu99"
TARGET_CFLAGS="$TARGET_CFLAGS -std=gnu99"

Best regards,
-- 
Javier Martinez Canillas
Software Engineer - Desktop Hardware Enablement
Red Hat