Re: Fix chdir-long.m4 caching

[Eric Blake]

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According to Eric Blake-1 on 9/26/2006 1:28 PM:
>> Well, here you go.  First, the patch makes the `AC_CACHE_CHECK' test
>> fail, so is incomplete.  So here's a patch to fix the test, also test
>> that we warn in the literal case, and add a case with a m4 macro.  This
>> is where my previous patch failed.  I guess you'd suggest I need to rip
>> off a set of `[]' quotes from the second argument of AC_CACHE_CHECK.
>> I'd argue that this could be a backward incompatibility for user code.
> 
> Ouch - that means AS_LITERAL_IF gets things wrong when we pass
> a macro that expands to a non-literal.  This sounds like you uncovered
> a bigger bug, and I'm not sure what impact it would have if we changed
> AS_LITERAL_IF to check for m4 macros, and/or change AS_VAR_SET
> to properly quote.

On second thought, it looks like libtool exploits the fact that the first
argument to AC_CACHE_VAR can be a macro, so we definitely need to keep
this case working.  But it still might be worth making AS_LITERAL_IF
recognize when it is handed a macro name that would expand to a non-literal.

- --
Life is short - so eat dessert first!

Eric Blake             address@hidden
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