On Wed, 5 Sep 2018 at 21:14, will wray <wjwray@xxxxxxxxx> wrote: > > Following instructions here: https://gcc.gnu.org/install/index.html > on Fedora 28 with gcc (GCC) 8.1.1 20180712 (Red Hat 8.1.1-5). > > First, the build hit a couple of -Werror fails so I reconfigured with > -disable-werror > then I get: Comparing stages 2 and 3, Bootstrap comparison failure! > > Do I disable comparison? Disable bootstrap? > Any other suggestions on doing a fresh build? > > > svn checkout svn://gcc.gnu.org/svn/gcc/trunk gcc > > mkdir build > > cd build > > mkdir gcc > > mkdir install > > cd gcc > > ../../gcc/configure --prefix=$HOME/repos/build/install > --enable-languages=c,c++ --disable-multilib > > make BOOT_CFLAGS='-O' bootstrap > > ... > ./insn-opinit.h:358:40: error: ‘icode’ may be used uninitialized in this > function [-Werror=maybe-uninitialized] > 358 | #define GEN_FCN(CODE) (insn_data[CODE].genfun) > ... > ../../../gcc/gcc/config/i386/i386.c:4514:32: error: ‘mask’ may be used > uninitialized in this function [-Werror=maybe-uninitialized] > 4514 | opts->x_recip_mask_explicit |= mask; > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~ > cc1plus: all warnings being treated as errors > ... > > > make clean "make clean" is known to not do a very good job of cleaning up. Just delete the entire ~/repos/build/gcc directory and start again from the configure command. > > ../../gcc/configure --prefix=$HOME/repos/build/install The installation docs say "building where objdir is a subdirectory of srcdir is unsupported." It can work, but I avoid it. Build in a directory outside the source dir. > --enable-languages=c,c++ --disable-multilib -disable-werror > > make > > ... > Comparing stages 2 and 3 > Bootstrap comparison failure! > gcc/gcc.o differs > gcc/plugin.o differs > ... I don't know why you'd get a comparison failure. If it still happens after starting again in an empty directory try it without the BOOT_CFLAGS=-O
