Re: document a surprising behaviour of macros AC_PROG_{CC,CXX,F77}

[Stefano Lattarini]

At Sunday 28 February 2010, Ralf Wildenhues <address@hidden> 
wrote:
> Hi Stefano,
> 
> thanks for the patch, and sorry for the delay on this.
> 
> * Stefano Lattarini wrote on Sun, Feb 28, 2010 at 03:25:09PM CET:
> > This topic came up a while ago on bug-autoconf, but the patch I
> > posted there went unnoticed or was ignored.
> 
> Well, I put it off for later because the right thing to do here
> would be to also add a set of AC_PROG_{CC,...}_WORKS macros that
> people can then use.
That sounds like a good idea.

> Also, a statement like this:
>
> > This behaviour may seem
> > surprising, but probably it cannot be fixed without breaking
> > backward compatibility in some way.
> 
> states "we've given up on this", whereas the reason I've put it off
> was "I haven't done enough research to know for sure whether we
> can safely change semantics".
Oh.  My misunderstanding.  What about this statement instead?

 "This behaviour may seem surprising, but is presently kept for
  backward-compatibility reasons.  This might change in a future
  version, though, so try not to rely too much on it."

> The use of AC_REQUIRE tends to require us to provide macros which
> do not take arguments in the vast number of default uses, so that
> we can easily let them be required.  Adding options IF-FAILS
> arguments to the AC_PROG_{CC,...} macros is bad because some of
> them already have optional arguments, some used to have them, and
> they are often AC_REQUIREd without options.
> 
> IOW, I'd prefer to not promise anything now which we may be able to
>  fix in a better way later.
Good points.  My patch feels much less compelling now.

Regards,
     Stefano