Re: Detecting that AC_PROG_LIBTOOL has been invoked

[Eric Blake]

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According to Paolo Bonzini on 12/14/2007 7:03 AM:
>> What is the m4_provide_if?  I didn't find it in the manual of autoconf
>> and m4.
> 
> It's in m4sugar.
> 
>> Anyways, does this guarantee me that the user did INVOKE the give
>> macros, not merely that they exist?

Actually, m4_provide_if/AC_PROVIDE_IFELSE([macro]) guarantees that someone
has previously called m4_provide/AC_PROVIDE([macro]), whether or not it
has been invoked.  There are situations where you can have an alternative
macro that does the same or better than the original macro, in which case
the alternative can call m4_provide([original]); this also guarantees that
attempts to later call the less-powerful original will be diagnosed, since
the interface was already provided by the alternative.

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

Eric Blake             address@hidden
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