[Mesa-dev] [PATCH] autoconf: Enable missing-prototypes errors when available.

[Kenneth Graunke]

On 01/27/2012 11:58 AM, Eric Anholt wrote:
> After the removal of the dri driver link test, this should help avoid
> the original problem that it was designed to catch: The warning about
> a missing prototype due to typoing a function name scrolling by in the
> Mesa build spew, and you not noticing until you try to run an
> application and it falls back to swrast.
> ---
>   configure.ac |   15 ++++++++++++++-
>   1 files changed, 14 insertions(+), 1 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 06d400f..0cd8421 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -176,7 +176,20 @@ esac
>
>   dnl Add flags for gcc and g++
>   if test "x$GCC" = xyes; then
> -    CFLAGS="$CFLAGS -Wall -Wmissing-prototypes -std=c99"
> +    CFLAGS="$CFLAGS -Wall -std=c99"
> +
> +    # Enable -Werror=implicit-function-declaration and
> +    # -Werror=missing-prototypes, if available, or otherwise, just
> +    # -Wmissing-prototypes.  This is particularly useful to avoid
> +    # generating a loadable driver module that has undefined symbols.
> +    save_CFLAGS="$CFLAGS"
> +    AC_MSG_CHECKING([whether $CC supports -Werror=missing-prototypes])
> +    CFLAGS="$CFLAGS -Werror=implicit-function-declaration"
> +    CFLAGS="$CFLAGS -Werror=missing-prototypes"
> +    AC_LINK_IFELSE([AC_LANG_PROGRAM()],
> +		   AC_MSG_RESULT([yes]),
> +		   [CFLAGS="$save_CFLAGS -Wmissing-prototypes";
> +		    AC_MSG_RESULT([no])]);
>
>       # Enable -fvisibility=hidden if using a gcc that supports it
>       save_CFLAGS="$CFLAGS"

Looks OK to me.  I've wondered whether we want to import the macro for 
checking these things from xorg-util-macros, since we'll probably want 
to do this for a few other ones too.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>