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Re: Avoid syntax error if IF-TRUE part of AM_COND_IF is empty.
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From: |
Eric Blake |
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Subject: |
Re: Avoid syntax error if IF-TRUE part of AM_COND_IF is empty. |
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Date: |
Tue, 27 Jul 2010 14:33:03 -0600 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.7) Gecko/20100720 Fedora/3.1.1-1.fc13 Lightning/1.0b2pre Mnenhy/0.8.3 Thunderbird/3.1.1 |
On 07/27/2010 01:33 PM, Ralf Wildenhues wrote:
> Adding this patch to maint to fix the glitch at least for the IF-TRUE
> case. It's unfortunately not fixable as nicely in the IF-FALSE case
> since we don't want to override $? there.
>
> @@ -27,8 +27,8 @@ AC_DEFUN([AM_COND_IF],
> [m4_ifndef([_AM_COND_VALUE_$1],
> [m4_fatal([$0: no such condition "$1"])])dnl
> _AM_COND_IF([$1])dnl
> -if _AM_COND_VALUE_$1; then
> - m4_default([$2], [:])
> +if _AM_COND_VALUE_$1; then :
> + m4_n([$2])[]dnl
Rather than open-coding the shell if, why not use:
AS_IF([_AM_COND_VALUE_$1],
[m4_n([$2])[]dnl
m4_ifval([$3], [_AM_COND_ELSE([$1])],
[body of else])
which (should) take care of an empty else for you as well, if AS_IF is
up to par (and if not, report that on the autoconf list).
--
Eric Blake address@hidden +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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