Understanding Multilibs ;-)

[Nathanael Nerode]

So, I decided to take a crack at moving multilibbing to the top level.

What I'm getting confused by at first is how the list of multilibs is 
generated.

At first it looked simple: just call gcc --print-multi-lib.  
Of course it couldn't be *that* simple.  ;-)

config-ml.in does various per-target per-'enable'-option pruning of the
list before operating.  But in the code it puts into Makefiles, 'gcc 
--print-multi-lib' is just used directly.  Hmm?

-----
Well, in any case, what I want to do is this.
* Get the list of lib versions and corresponding options.  
(`gcc --print-multi-lib` if that's really sufficient).

* Create a target subdir for each one (assuming 'a' and 'b' are the 
lib variants)...
i686-pc-linux/a/libstdc++-v3
i686-pc-linux/a/libf2c
i686-pc-linux/b/libstdc++-v3
i686-pc-linux/b/libf2c
etc...

* Configure each one appropriately from the top level (that's the easy 
part, since it's just programming ;-) ).


What are the difficulties I can expect to hit in doing this?

-- 
Nathanael Nerode  <neroden at gcc.gnu.org>
http://home.twcny.rr.com/nerode/neroden/fdl.html