Re: Make depmode=cpp work with Microsoft Visual C++ on MSYS.

[Ralf Wildenhues]

* Peter Rosin wrote on Fri, Jan 30, 2009 at 11:20:13AM CET:
>
> Here is an update that forks *a lot* less.

Thanks.

> Dependencies work as far as I can see when I compile libltdl using
> MSVC on both Cygwin (depmode=msvisualcpp) and MSYS (depmode=msvcmsys).

Just to be sure: that means
- it doesn't cause spurious rebuilds when nothing has changed,
- it rebuilds when a (directly or indirectly) included header changed,
- it fails to fully rebuild if a header is removed, or changed to
  contain a synyax error.
Right?

> But native MSVC on
> Cygwin fails during link, but that's totally unrelated...

Please, post error output for such a statement.

> ("cygpath -f -" support was checked into cvs April 2000.)

OK.

> +2009-01-30  Peter Rosin  <address@hidden>
> +
> +     Add depmode=msvcmsys for Microsoft Visual C++ on MSYS.
> +     * lib/depcomp [msvisualcpp]: Fork fewer processes. Filter out
> +     libtool in the preprocessor invocation (as is done in
> +     depmode=cpp). Silence compiler stderr.
> +     [msvcmsys]: New depmode as a derivative of depmode=msvisualcpp.
> +     msvcmsys transforms any backslashes into forward slashes to
> +     make the grep in depend.m4 match, instead of the "cygpath -u"
> +     that is used in msvisualcpp.

Hmm.  Can you expand on this a bit?  The way I read this now, it looks
like we're working around some wart in depend.m4.  But from the
discussion, I gather that you're doing this forward/backward slashes
thing in order to be able to differentiate between Cygwin and MinGW.
Is that correct?  If not, why not change depend.m4 to fit?  Then you
can save another fork with MSYS, by factorizing a bit differently.

No need to generate a new patch, I'm just asking for clarification at
this point.

Thanks,
Ralf