[Bug plugins/53126] gcc-4.7.0 error "gcc-ar: Cannot find plugin"

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53126

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-05-02 19:39:11 UTC ---
Created attachment 27290
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27290
gcc48-pr53126.patch

Ugh, what gcc-ar does isn't even remotely matching to what gcc does.

If GCC_EXEC_PREFIX isn't in the environment, then it will
      gcc_libexec_prefix = get_relative_prefix (decoded_options[0].arg,
                                             standard_bindir_prefix,
                                             standard_libexec_prefix);
and when it is there, it will:
      /* make_relative_prefix requires a program name, but
         GCC_EXEC_PREFIX is typically a directory name with a trailing
         / (which is ignored by make_relative_prefix), so append a
         program name.  */
      char *tmp_prefix = concat (gcc_exec_prefix, "gcc", NULL);
      gcc_libexec_prefix = get_relative_prefix (tmp_prefix,
                                                standard_exec_prefix,
                                                standard_libexec_prefix);

      /* The path is unrelocated, so fallback to the original setting.  */
      if (!gcc_libexec_prefix)
        gcc_libexec_prefix = standard_libexec_prefix;

Even if GCC_EXEC_PREFIX isn't in the environment, and gcc_libexec_prefix is
NULL after this, we end up doing
  /* If we don't know where the toolchain has been installed, use the
     configured-in locations.  */
  if (!gcc_exec_prefix)
    {
#ifndef OS2
      add_prefix (&exec_prefixes, standard_libexec_prefix, "GCC",
                  PREFIX_PRIORITY_LAST, 1, 0);
      add_prefix (&exec_prefixes, standard_libexec_prefix, "BINUTILS",
                  PREFIX_PRIORITY_LAST, 2, 0);
...
so I'd say what this patch does brings it at least a little bit closer to what
gcc driver does.  Having make_relative_prefix return NULL is actually the
common case where the compiler is installed where it has been configured.