GNU bug report logs - #23760
25.0.95; emacs 25.0.95 doesn't build with glibc-2.23.90

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Florian Weimer <fweimer <at> redhat.com>, Jan Synáček <jsynacek <at> redhat.com>
Cc: Glenn Morris <rgm <at> gnu.org>, 23760 <at> debbugs.gnu.org
Subject: bug#23760: 25.0.95; emacs 25.0.95 doesn't build with glibc-2.23.90
Date: Mon, 20 Jun 2016 12:04:50 +0200

On 06/20/2016 11:21 AM, Florian Weimer wrote:
>
> The usual mechanism for deprecation and removal of an API does not 
> work if the symbol is interposed because it will be unversioned, and 
> unversioned symbols preempt versioned symbols.  As a result, even if 
> the symbol is a compat symbol, you can produce new binaries which use 
> the removed API.
>

True, but in this particular case Emacs is replacing malloc as well as 
__malloc_initialize_hook etc., so I don't see a problem. Although new 
Emacs binaries will still use the removed API, they will also support 
the removed API.

What *could* be a problem is if the new glibc malloc API supplies 
symbols that Emacs does not supply, and if other parts of the new glibc 
use these symbols. But I don't see this happening either (and if it did 
happen, poisoning __malloc_initialize_hook wouldn't fix it).

Perhaps poisoning __malloc_initialize_hook helps for some theoretical 
applications, but for Emacs I don't see how it is a win.

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