Implement -MF <output-filename>

[Neil Booth]

Zack Weinberg wrote:-

> I like it overall.
> 
> It is difficult for me to comprehend your patch since it's got
> substantial code rearrangement on top of the semantic changes.

Unfortunately, yes.

> There's no change log for gcc.c.

Well spotted.  I'll fix that.  We need a new patch anyway as this
doesn't bootstrap (see other post) because of front-end issues.

> -MD expands to -M -MF %b.d.  %b is the basename of the input file -
> no directory component.  Is this what we want?  We just went through
> changing the target name in dependency output to include the
> directory.  However, since -MD's always done this, we can worry about
> it later.

That's what I was doing - going to leave it for a subsequent patch.
There will probably be overlap with Nathan's patch for that.

> Do we have documentation in cpp.texi for all these new options?

In cpp.texi, yes, and after this patch in the run-time help too.

We don't have it in gcc.texi for CPP; this duplication of
documentation is a pain.  Similarly for extend.texi.  I was going to
wait until it had settled before updating those.

How's your documentation rewrite coming on?

Neil.