bug#7669: option "foreign" after "-Wall" turns off and portability warnings.

[Ralf Wildenhues]

* Stefano Lattarini wrote on Fri, Dec 17, 2010 at 07:52:29PM CET:
> With automake >= 1.10, foreign *after* -Wall in AM_INIT_AUTOMAKE turns
> off portability warnings.

> While the current behaviour is due to various historical and implementation
> reasons, IMHO it is counter-intuitive and somewhat "dangerous", since
> programmers enabling the `foreign' option might unwittingly be prevented
> from seeing portability warnings -- when they think to have enabled those
> warnings!

Fixing this will turn (at least user-provided) silent-rules rules noisy,
I think.  Given however that the nested variable expansion involved may
be in a future Posix (if I get to analyzing the remaining questions from
Eric in time), one possible strategy out is optimistically not warning
about them any more and otherwise letting me get to the testing ... ;-)

I'm not sure if there were also other reasons for the current behavior,
but I think the discussion at the time the patches were put in place
should reveal that.

And yes, I agree that the behavior is bad.

Thanks for looking into this,
Ralf