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

[Leif Lindholm <leif@nuviainc.com>]

On Fri, Apr 03, 2020 at 14:45:01 +0200, 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

Drop "do not"?

> we strongly require a feature from newer C standard.
> 
> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
> ---
> 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
>  
> +BUILD_CFLAGS="-std=gnu99 $BUILD_CFLAGS"
> +HOST_CFLAGS="-std=gnu99 $HOST_CFLAGS"
> +TARGET_CFLAGS="-std=gnu99 $TARGET_CFLAGS"

Agree with Javier that it would be helpful to explain reason for
enforcing gnu99 in a comment.

"// Enable support for 'restrict' keyword"
Would be enough.

/
    Leif

> +
>  # Default HOST_CPPFLAGS
>  HOST_CPPFLAGS="$HOST_CPPFLAGS -Wall -W"
>  HOST_CPPFLAGS="$HOST_CPPFLAGS -DGRUB_UTIL=1"
> -- 
> 2.11.0
>