Re: AC_DEFUN_ONCE semantics

[Eric Blake]

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According to Eric Blake on 1/26/2009 2:06 PM:
> 
> AC_DEFUN_ONCE([foo], [bar])
> AS_IF([:], [foo])
> 
> Before the patch, foo was expanded inside the conditional; after the patch, 
> foo 
> is hoisted and expanded before the conditional.  Yes, hopefully this is a 
> small 
> incompatibility; but hopefully it only results in longer execution time in 
> the 
> case where the shell condition used to skip the processing of foo.

On the other hand, the manual already said that inside the body of an
AC_DEFUN'd macro (such as AS_IF), you should use AC_REQUIRE([foo]), never
direct foo.  So if you were already obeying the manual, you should never
run into this particular change in semantics.

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

Eric Blake             address@hidden
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