libstdc++, autoconf, and /lib/cpp (was Fw: Re: GCC 3.0 Status , Report)

[Benjamin Kosnik]

> I'm changing the subject line because otherwise I get the most bizzare
> conversations all threaded under "3.0 Status Report" due to the followups
> from Mark's announcements.

Yeah. Mark, anyway you could do weekly/monthly status email with the 
week/month in the title? Might make more sense.

> There's also a bit on the GCC configuration instructions page which adds
> 
> #   Some options which only apply to building cross compilers:
> #
> #   --with-headers=dir -- Specifies a directory which has target include
> #   files. This options is required when building a cross compiler, if
> #   ${prefix}/${target}/sys-include doesn't pre-exist.

shouldn't have to do this

> Anyhow, I made an empty foo/sh-elf/sys-include directory, touch'd an
> empty stdlib.h, and configured with --prefix=foo --target=sh-elf, and
> the configure went just fine[*].  The half-dozen calls to v3's configure
> worried me until I realized that it really does have all those multilibs.

Yep.

> > I suppose we could just use AC_TRY_COMPILE here.
> 
> Wouldn't that be tricker than calling just the preprocessor?  If the system
> headers aren't being found during configure, then things are only going
> to get worse.

The thought is that CXX gets passed down and set correctly, whereas CPP 
isn't or doesn't, I'm not quite sure which. So, it might be an effective 
work-around to just use AC_TRY_COMPILE, and thus CXX. 

-benjamin