Re: m4_copy and m4_rename semantic changes

[Eric Blake]

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According to Ralf Wildenhues on 5/30/2009 3:51 AM:
> Hello Eric, Paolo,
> 
> m4_copy and m4_rename changed their API before being published.
> GCC already uses these macros from Autoconf 2.59, and expects
> the old semantics.  I need to add some m4_undefine in order to
> avoid autoconf failures.

Can you point to your gcc patch, so I can see exactly what semantic
difference they were depending on?

> Just FYI.  Even with these previously undocumented macros, changes
> might break software.  It might be a good idea to note the m4_copy
> and m4_rename issue a bit more prominently in NEWS.

If I'm going to touch up the NEWS item to mention how code can be portably
written to use either the older undocumented semantics or the new
documented ones, then I'd like to know exactly what had to be done here.

> Also, GCC makes use of the undefined (and recently removed) macro
> _AC_CHECK_HEADER_OLD.

I agree with Paolo's idea of adding an AU_DEFUN.  I'll see if I can get to
that today.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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