GCC Warning on MIPS

[Ralf Corsepius]

On Tue, 2008-04-22 at 16:22 -0500, Joel Sherrill wrote:
> Ralf Corsepius wrote:
> > On Tue, 2008-04-22 at 10:13 -0500, Joel Sherrill wrote:
> >   
> >> Ralf Corsepius wrote:
> >>     
> >>> On Tue, 2008-04-22 at 10:01 -0500, Joel Sherrill wrote:
> >>>
> >>>       
> >>>> Ralf Corsepius wrote:
> >>>>
> >>>>         
> >>>>> On Tue, 2008-04-22 at 09:25 -0500, Joel Sherrill wrote:
> >>>>>
> >>>>>
> >>>>>           
> >>>>>> Ralf,
> >>>>>>
> >>>>>> I know neither of us go digging through build
> >>>>>> logs when the build works, but I came across this
> >>>>>> warning building GCC SVN trunk targeting mips-rtems4.9
> >>>>>>
> >>>>>> In file included from ./tm.h:10,
> >>>>>>                  from ../../gcc/gcc/gencheck.c:24:
> >>>>>> ../../gcc/gcc/config/rtems.h:21:1: warning: "NO_IMPLICIT_EXTERN_C" redefined
> >>>>>> In file included from ./tm.h:8,
> >>>>>>
> >>>>>> Not critical but is repeated about 10,000 times. :-D
> >>>>>>
> >>>>>> I think the #define NO_IMPLICIT_EXTERN_C in gcc/config/rtems.h
> >>>>>> needs an ifndef or an undef added.
> >>>>>>
> >>>>>> What do you think we need to do?
> >>>>>>
> >>>>>>
> >>>>>>             
> >>>>> Hmm, do you have this patch below applied?
> >>>>>
> >>>>> diff -Naur gcc-4.3.0.orig/gcc/config/mips/elf.h gcc-4.3.0/gcc/config/mips/elf.h
> >>>>> --- gcc-4.3.0.orig/gcc/config/mips/elf.h        2007-08-02 12:49:31.000000000 +0200
> >>>>> +++ gcc-4.3.0/gcc/config/mips/elf.h     2008-03-06 16:22:30.000000000 +0100
> >>>>> @@ -48,6 +48,4 @@
> >>>>>  #undef  ENDFILE_SPEC
> >>>>>  #define ENDFILE_SPEC "crtend%O%s crtn%O%s"
> >>>>>
> >>>>> -#define NO_IMPLICIT_EXTERN_C 1
> >>>>> -
> >>>>>  #define HANDLE_PRAGMA_PACK_PUSH_POP 1
> >>>>>
> >>>>>
> >>>>> This is a general bug in the mips port (I _know_ it is), but ...
> >>>>> upstream refuses to apply it, which forces us to keep it as a separate
> >>>>> patch :)
> >>>>>
> >>>>>
> >>>>>
> >>>>>           
> >>>> In many cases throughout the gcc config files, they just undef
> >>>> the previous one and redefine.  In the above, ENDFILE_SPEC
> >>>> is done that way.  Three of the five definitions in config/rtems.h
> >>>> have an undef in front of them.  Would it be so bad to just
> >>>> do that for the rest of the ones in rtems.h?
> >>>>
> >>>>         
> >>> Why should they?
> >>>
> >>> Wrt. to NO_IMPLICIT_EXTERN_C, to me this doesn't make any sense at all.
> >>>
> >>>
> >>>       
> >> Maybe not but there is precedence for it.  The shared
> >> config files for a number of other OSes do this:
> >>
> >> [joel at iceland config]$ grep -r NO_IMPLICIT_EXTERN_C .| grep ifndef |
> >> grep -v .svn
> >> ./lynx.h:#ifndef NO_IMPLICIT_EXTERN_C
> >> [joel at iceland config]$ grep -r NO_IMPLICIT_EXTERN_C .| grep undef| grep
> >> -v .svn
> >> ./netbsd.h:#undef  NO_IMPLICIT_EXTERN_C
> >> ./rs6000/sysv4.h:#undef  NO_IMPLICIT_EXTERN_C
> >> ./i386/sco5.h:#undef NO_IMPLICIT_EXTERN_C
> >> ./freebsd.h:#undef  NO_IMPLICIT_EXTERN_C
> >> ./vx-common.h:#undef  NO_IMPLICIT_EXTERN_C
> >> ./sparc/openbsd64.h:#undef NO_IMPLICIT_EXTERN_C
> >>     
> >
> > And where would be the sense behind this?
> >
> > We want to force NO_IMPLICIT_EXTERN_C.
> >
> > The bug is in mips/elf.h. This file belongs to the mips backend.
> >
> > This file simply is broken by defining an OS specific flag such as
> > NO_IMPLICIT_EXTERN_C.
> >
> > Cf. how we set up _all_ other targets. The only one behaving differently
> > is this broken mips file.
> >   
> Then how about proposing a patch for the mips/elf.h file
> to gcc?
I did so long time ago (this patch is one of the oldest patches we carry
around for many years.)

The mips-maintainer had rejected it and claimed mips/elf.h to define
NO_IMPLICT_EXTERN_C to be correct..

Ralf