-B vs Multilib

[Jim Wilson]

Greg Schafer wrote:
> Currently, -B doesn't add the multilib search paths when processing
> startfile_prefixes. For example, -B $prefix/lib/ doesn't find startfiles in
> $prefix/lib/../lib64

GCC has two different schemes for multilib search dirs.  One that is 
used in the gcc build tree, and one that is used in the OS install dirs. 
  See the difference between multilib_dir and multilib_os_dir.

We are doing multilib searches for startfile_prefix.  See find_file. 
However, we are using the gcc build tree form.  This is necessary 
because -B options are used during the gcc build.

Perhaps what you need is to make -B options work both ways, so that they 
are also useful when pointing into OS dirs like /lib.  Or maybe we need 
yet another option which is like -B but meant to be used in OS dirs 
instead of in the gcc build tree.

Jim