Understanding Multilibs ;-)

[Nathanael Nerode]

Phil Edwards wrote:
> Some questions at random:
> 
> What is 'a' in the standard/normal/primary/nothing-special case?
Nothing.
So ${target}/libstdc++-v3/

> 
> What are the names for combinations?  'ab'?
a/b ?
So
${target}/a/b/libstdc++-v3/

I believe there's a specified order in each case, so that we know 
whether to do a/b or b/a, right?

> Can we do this in such a way to preserve this bit snagged from config-ml.in:
> 
>   # The build tree is layed out as
>   #
>   # ./
>   #   newlib
>   #   m68020/
>   #          newlib
>   #          m68881/
>   #                 newlib
To be perfectly honest, I don't understand this bit.  :-)  The layout 
sounds truly bizarre to me, *and* doesn't seem to correspond to reality.

...Unless the one listed lower down is the 'combo' of m68020 and m68881, 
  and there's no 'just m68881' option, in which case, yes, that's right. :-)

>   #
>   # The nice feature about this arrangement is that inter-library references
>   # in the build tree work without having to care where you are.
This we should undoubtedly be able to preserve.  In fact, the whole 
point of moving multilibbing to the top level is that the subdirectories 
should never have to care where they are.