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

[Lucas Stach]

CC'ing Ian, as he was the one who added glDrawBuffersNV.

The warning about the missing prototype was there for a long time. Only
now with Werror=missing-prototypes it is fatal for the build.

Am Dienstag, den 31.01.2012, 13:45 +0000 schrieb Jon TURNEY:
> On 27/01/2012 19:58, 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 like this change breaks compilation of the C dispatch code, see [1], [2].
> 
> In file included from glapi_dispatch.c:91:
> ../../../src/mapi/glapi/glapitemp.h:4641: error: no previous prototype for
> 'glDrawBuffersNV'
> 
> 
> [1] http://tinderbox.freedesktop.org/builds/2012-01-31-0012/logs/libGL/#build
> [2]
> http://tinderbox.freedesktop.org/builds/2012-01-31-0012/logs/libGL-indirect-only/#build
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