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Re: Call the AC_CHECK_HEADER macro on a condition

From: Julien ÉLIE
Subject: Re: Call the AC_CHECK_HEADER macro on a condition
Date: Tue, 19 Apr 2016 22:40:49 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.7.2

Hi all,

- Second is to rewrite your condition using AS_IF, which automatically
   "hoists" the dependency AC_PROG_CPP (and any other dependencies)
   outside of the if condition.

I just wanted to thank you for this explanation. I was not affected by
the original issue, but your answer was very useful. Until now, I
thought AS_IF() was just a stupid wrapper around the shell's if clause,
but your answer makes it clear that it is a lot smarter than that.

So did I!

Incidentally, I am aware of AS_IF and AS_CASE constructions, as described in <>.
Is it planned to add other macros like AS_FOR, AS_WHILE...?

One may consider doing something like:

for header in $LIST ; do AC_CHECK_HEADER([$header]) ; done

If I understand well, in case $LIST happens to be empty, AC_PROG_CPP will never be run, and subsequent calls to AC_CHECK_HEADER in the configure script will fail.

Julien ÉLIE

« Je sens que ma dernière hure est proche ! » (Astérix)

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