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Re: [PATCH] autoconf: warn if AC_*_IFELSE lacks complete program
From: |
Ralf Wildenhues |
Subject: |
Re: [PATCH] autoconf: warn if AC_*_IFELSE lacks complete program |
Date: |
Fri, 27 Aug 2010 19:28:08 +0200 |
User-agent: |
Mutt/1.5.20 (2010-04-22) |
* Eric Blake wrote on Fri, Aug 27, 2010 at 03:59:00PM CEST:
> On 08/26/2010 11:24 PM, Ralf Wildenhues wrote:
> >Is
> > m4_pushdef([M]) m4_define([M]) m4_popdef([M])
> >
> >documented to work and do the expected (what would that be?) thing?
>
> Yes - [...]
> (Some other m4 implementations are
> documented where m4_define wipes out the entire pushdef stack,
> rather than the top-most definition on the stack, and POSIX allows
> that alternate semantic, but it would break m4sugar.)
Ah, that bit of semantics had evaded me so far.
> On
> the other hand, AC_COMPILE_IFELSE(AC_LANG_DEFINES_PROVIDED) (note
> the missing quoting) expands to:
>
> m4_define([a],[nowarn])m4_pushdef([a],[warn])a()m4_popdef([a])
>
> and still issues a warning, because the AC_LANG_DEFINES_PROVIDED was
> expanded too early, and the expansion of a is still tied to the
> [warn] from the pushdef.
Yup, seeing that in a couple of cases in Libtool, which I'm going to fix
next.
Thanks,
Ralf