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List:       gnulib-bug
Subject:    Re: [libvirt] [PATCH] Revert "maint: Update to latest gnulib"
From:       Eric Blake <eblake () redhat ! com>
Date:       2017-08-24 19:53:12
Message-ID: 64d0b7db-a571-0da0-3d15-ca2b8c211c2b () redhat ! com
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On 08/24/2017 02:36 PM, Bruno Haible wrote:
> [trimming extra CCs]
> 
> Hi Eric,
> 
>> Where looking through autoconf history, was indeed something that
>> autoconf fixed in commit 9f28c6e (autoconf 2.63b) (CentOS 6 is still
>> stuck on the older autoconf 2.63).
>> https://lists.gnu.org/archive/html/autoconf-patches/2009-01/msg00051.html
>>
>> Sadly, I didn't quickly find a workaround in the archives for how to NOT
>> trace a macro whose name is problematic
> 
> You can modify m4/manywarnings.m4:
> 
> 1) rename
>   AC_DEFUN([gl_MANYWARN_ALL_GCC(C)],
> to
>   AC_DEFUN([gl_MANYWARN_ALL_GCC__C],

Not as elegant as autoconf's internals, but looks like it will do the
trick.  I'll play with it in the context of libvirt, since that's where
I have a known reproducer, and with any luck, will push something to
gnulib later today.

> 
> 2) rename
>   AC_DEFUN([gl_MANYWARN_ALL_GCC(C++)],
> to
>   AC_DEFUN([gl_MANYWARN_ALL_GCC__CXX],
> 
> 3) modify line 39
> _AC_LANG_DISPATCH([$0], _AC_LANG, $@)
> to make an indirection to [gl_MANYWARN_ALL_GCC__]_AC_LANG_PREFIX
> 
> I was working with this naming scheme in a draft patch. It is not as elegant
> as the current one, but should work around against said bug (if I have
> understood it correctly).

Yes, the bug is entirely in the fact that older autoconf did not
properly shell-quote macro names to be traced, limiting the use of any
macro that aclocal must find to those that are named without shell
metacharacters.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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