[Bug driver/81829] [7 Regression] /usr/bin/gcc-{ar,nm,ranlib} segfault without arguments

["marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81829

--- Comment #6 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Xi Ruoyao from comment #5)
> (In reply to Martin Liška from comment #4)
> > (In reply to Xi Ruoyao from comment #3)
> > > marxin's patch:
> > > 
> > > http://gcc.gnu.org/ml/gcc-patches/2017-08/msg01116.html
> > > 
> > > But this patch doesn't work while /my_bin/bin contains a symlink.
> > 
> > Can you please describe your set up is more detail?
> 
> cd $BLDDIR
> $SRCDIR/configure && make -j$CPUNUM
> cd gcc
> for i in ar nm ranlib; do ln -sv gcc-$i $i; done
> export PATH=$PWD:$PATH
> ar
> (fork infinite processes)
> 
> Since my BLDDIR is /home/xry111/build/gcc, and /home/xry111/build is linked
> to
> /mnt/mm1/xry111, remove_prefix failed to remove /home/xry111/build/gcc/gcc
> from
> the prefixes.  If change to
> 
> export PATH=$(realpath $PWD):$PATH
> 
> It would be ok.

Huh, so many beasts out there.
What can you see with following patch:

diff --git a/gcc/gcc-ar.c b/gcc/gcc-ar.c
index 1155ba83e35..452ca87d2ce 100644
--- a/gcc/gcc-ar.c
+++ b/gcc/gcc-ar.c
@@ -199,6 +199,8 @@ main (int ac, char **av)

       /* If the exe_name points to the wrapper, remove folder of the wrapper
         from prefix and try search again.  */
+      fprintf (stderr, "exe_name: %s, wrapper_file: %s\n", exe_name,
+              wrapper_file);
       if (strcmp (exe_name, wrapper_file) == 0)
        {
          char *exe_folder = wrapper_file;

It's probably related to lrealpath that does not follow links. Btw. is your
link a mount?
I'm tending to remove the whole smartness of gcc-ar that removes the prefix.

Martin