[Bug bootstrap/47422] New: [4.6 regression] bootstrap failure due to warnings in compare-elim.c

["mikpe at it dot uu.se" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47422

           Summary: [4.6 regression] bootstrap failure due to warnings in
                    compare-elim.c
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: mikpe@it.uu.se


Bootstrapping 4.6-20110122 on powerpc64-linux fails with:

/mnt/archive/gcc-4.6-20110122/gcc/compare-elim.c: In function
'maybe_select_cc_mode':
/mnt/archive/gcc-4.6-20110122/gcc/compare-elim.c:407:58: error: unused
parameter 'b' [-Werror=unused-parameter]
cc1: all warnings being treated as errors

make[3]: *** [compare-elim.o] Error 1
make[3]: *** Waiting for unfinished jobs....
rm gcj-dbtool.pod jcf-dump.pod jv-convert.pod grmic.pod gcj.pod gc-analyze.pod
cpp.pod gfdl.pod gij.pod gcov.pod gfortran.pod fsf-funding.pod gcc.pod
make[3]: Leaving directory `/mnt/archive/objdir46/gcc'
make[2]: *** [all-stage2-gcc] Error 2
make[2]: Leaving directory `/mnt/archive/objdir46'
make[1]: *** [stage2-bubble] Error 2
make[1]: Leaving directory `/mnt/archive/objdir46'
make: *** [bootstrap] Error 2

The problem is that the rs6000 SELECT_CC_MODE macro ignores its last parameter,
so the 'b' parameter to maybe_select_cc_mode is unused, triggering the error.

Targets without SELECT_CC_MODE (e.g. m68k) also break, see
<http://gcc.gnu.org/ml/gcc-patches/2011-01/msg01607.html>.