[Bug preprocessor/30926] New: undef prepocessor directive ignored ?

["maxim_m at gmx dot net" <gcc-bugzilla at gcc dot gnu dot org>]

trying to build cvs glibc as per instructions at cross-lfs.org's sysroot
branch.

with recent versions of mainline trunk(statically linked, no threads build) i
get build errors like:

../sysdeps/ieee754/dbl-64/s_signbit.c:27: error: redefinition of '__signbit'
../sysdeps/x86_64/fpu/bits/mathinline.h:43: error: previous definition of
'__sig              nbit' was here

it doesn't happen with 4.1

the command line was:
x86_64-maxxcorp-linux-gnu-gcc ../sysdeps/ieee754/dbl-64/s_signbit.c -c
-std=gnu99 -O2 -Wall -Winline -Wwrite-strings -combine -fmerge-all-constants
-m64 -march=athlon64 -save-temps -Wstrict-prototypes -Wno-uninitialized
-D__NO_MATH_INLINES -D __LIBC_INTERNAL_MATH_INLINES -I../include
-I/mnt/lfs/sources/glibc-build/math -I /mnt/lfs/sources/glibc-build
-I../sysdeps/x86_64/elf -I../nptl/sysdeps/unix/sysv/linux/x86_64
-I../sysdeps/unix/sysv/linux/x86_64 -I../sysdeps/unix/sysv/linux/wordsize-64
-I../nptl/sysdeps/unix/sysv/linux -I../nptl/sysdeps/pthread
-I../sysdeps/pthread -I../sysdeps/unix/sysv/linux -I../sysdeps/gnu
-I../sysdeps/unix/common -I../sysdeps/unix/mman -I../sysdeps/unix/inet
-I../nptl/sysdeps/unix/sysv -I../sysdeps/unix/sysv -I../sysdeps/unix/x86_64
-I../nptl/sysdeps/unix -I../sysdeps/unix -I../sysdeps/posix
-I../sysdeps/x86_64/fpu -I../nptl/sysdeps/x86_64 -I../sysdeps/x86_64
-I../sysdeps/wordsize-64 -I../sysdeps/ieee754/ldbl-96
-I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 -I../sysdeps/ieee754
-I../sysdeps/generic/elf -I../sysdeps/generic -I../nptl  -I.. -I../libio -I.
-nostdinc -isystem
/mnt/lfs/cross-tools/lib/gcc/x86_64-maxxcorp-linux-gnu/4.3.0/include -isystem
/mnt/lfs/usr/include -D_LIBC_REENTRANT -include ../include/libc-symbols.h      
-o /mnt/lfs/sources/glibc-build/math/s_signbit.o -MD -MP -MF
/mnt/lfs/sources/glibc-build/math/s_signbit.o.dt -MT
/mnt/lfs/sources/glibc-build/math/s_signbit.o


-- 
           Summary: undef prepocessor directive ignored ?
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: maxim_m at gmx dot net
 GCC build triplet: x86_64-cross-linux-gnu
  GCC host triplet: x86_64-maxxcorp-linux-gnu
GCC target triplet: x86_64-maxxcorp-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30926