On SuSe linux 10.0 with gcc 4.0.2 installed 
(
~/import/gcc-3.2.3/objdir> uname -a
Linux djebe 2.6.13-15-smp #1 SMP Tue Sep 13 14:56:15 UTC 2005 i686 i686 i386
GNU/Linux
)
trying to bootstrap gcc 3.2.3 fails:
make bootstrap
.
.
.
much stuff deleted
.
.
.
gcc -c -DIN_GCC    -g  -W -Wall -Wwrite-strings -Wstrict-prototypes
-Wmissing-prototypes -Wtraditional -pedantic -Wno-long-long  -DHAVE_CONFIG_H
-DGENERATOR_FILE    -I. -I. -I../../gcc -I../../gcc/. -I../../gcc/config
-I../../gcc/../include ../../gcc/rtl.c -o rtl.o
In file included from ../../gcc/rtl.c:24:
../../gcc/rtl.h:125: warning: type of bit-field ‘code’
is a GCC extension
../../gcc/rtl.h:128: warning: type of bit-field ‘mode’
is a GCC extension
gcc -c -DIN_GCC    -g  -W -Wall -Wwrite-strings -Wstrict-prototypes
-Wmissing-prototypes -Wtraditional -pedantic -Wno-long-long  -DHAVE_CONFIG_H
-DGENERATOR_FILE    -I. -I. -I../../gcc -I../../gcc/. -I../../gcc/config
-I../../gcc/../include ../../gcc/read-rtl.c -o read-rtl.o
In file included from ../../gcc/read-rtl.c:24:
../../gcc/rtl.h:125: warning: type of bit-field ‘code’
is a GCC extension
../../gcc/rtl.h:128: warning: type of bit-field ‘mode’
is a GCC extension
../../gcc/read-rtl.c: In function
‘fatal_with_file_and_line’:
../../gcc/read-rtl.c:62: warning: traditional C rejects ISO C style function
definitions
../../gcc/read-rtl.c: In function ‘read_rtx’:
../../gcc/read-rtl.c:662: error: invalid lvalue in increment
make[2]: *** [read-rtl.o] Error 1
make[2]: Leaving directory `/home/slehr/import/gcc-3.2.3/objdir/gcc'
make[1]: *** [stage1_build] Error 2
make[1]: Leaving directory `/home/slehr/import/gcc-3.2.3/objdir/gcc'
make: *** [bootstrap] Error 2


-- 
           Summary: gcc 3.2.3 fails to bootstrap on linux when 4.0.2 is
                    preinstalled
           Product: gcc
           Version: 3.2.3
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: sl at datamyway dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30893