Re: compiler version checks

[Ralf Wildenhues]

[ dropping libtool-patches ]

Hi Eric,

* Eric Blake wrote on Tue, Apr 28, 2009 at 02:12:18AM CEST:
> According to Ralf Wildenhues on 4/27/2009 2:05 PM:
> 
> > +# Limit stderr logging to avoid copying full manpages.
> > +_AC_DO_LIMIT([$ac_compiler --version >&AS_MESSAGE_LOG_FD])
> > +_AC_DO_LIMIT([$ac_compiler -v >&AS_MESSAGE_LOG_FD])
> > +_AC_DO_LIMIT([$ac_compiler -V >&AS_MESSAGE_LOG_FD])
> > +_AC_DO_LIMIT([$ac_compiler -qversion >&AS_MESSAGE_LOG_FD])
> 
> Rather than have four consecutive copies of _AC_DO_LIMIT, wouldn't
> something more compact like this (untested) snippet work?
> 
> for ac_option in --version -v -V -qversion ; do
>   _AC_DO_LIMIT([$ac_compiler $ac_option >&AS_MESSAGE_LOG_FD])
> done

Sure.  Unfortunately, it wouldn't work to check the exit status of
the command, as some don't reliably fail with an unknown argument.

Output limiting is likely useful for several other logging cases,
but it is not as trivial to do with arbitrary tests, as we want to
be sure not to ever cut off a meaningful first error that comes
after lots of warnings.

Cheers,
Ralf