RFA: Fix other/44566

[Joseph S. Myers]

On Sun, 27 Jun 2010, Joern Rennecke wrote:

> Quoting Mark Mitchell <mark@codesourcery.com>:
> > All the work people are doing to help turn things into hooks, and such,
> > is of course a step in the right direction; part of what we need for
> > this is to avoid having target macros affecting the front- and
> > middle-end compiler components.
> 
> As my work shows, having the hooks coded in the individual targets is not
> required - using the existing macros to provide hooks works just fine.

It is fragile, because you need a way to ensure that no patch causes a use 
of a macro to be introduced in a file built once-only; if the target macro 
doesn't exist at all, there is no such risk.  Furthermore, one long-term 
aim of modularization is to be able to build front ends and back ends as 
plug-ins separately from the core compiler, which certainly requires 
completing the hook conversion rather than relying on building parts of 
the compiler twice.

-- 
Joseph S. Myers
joseph@codesourcery.com