GNU bug report logs - #37006
27.0.50; garbage collection not happening after 26de2d42

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Package: emacs;

Reported by: Joseph Mingrone <jrm <at> ftfl.ca>

Date: Sun, 11 Aug 2019 12:41:01 UTC

Severity: normal

Tags: patch

Found in version 27.0.50

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

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From: Mattias Engdegård <mattiase <at> acm.org>
To: jrm <at> ftfl.ca
Cc: Eli Zaretskii <eliz <at> gnu.org>, Paul Eggert <eggert <at> cs.ucla.edu>, 37006 <at> debbugs.gnu.org
Subject: bug#37006: 27.0.50; garbage collection not happening after 26de2d42
Date: Sun, 11 Aug 2019 18:23:28 +0200

[Message part 1 (text/plain, inline)]
Observed on macOS as well. Reason: free_cons has the condition

 if (INT_ADD_WRAPV (consing_until_gc, sizeof *ptr, &consing_until_gc))

which will return true (overflow) if consing_until_gc is negative, which is kind of defensible since sizeof is unsigned which causes the sum (consing_until_gc + sizeof *ptr) to be a large unsigned number that doesn't fit into consing_until_gc.

Clang 10 defines __GNUC__ to 4 which causes intprops.h to not use __builtin_add_overflow despite that being present and working.

Casting the sizeof should fix it; patch attached.


[0001-Avoid-unsigned-addend-in-overflow-check-bug-37006.patch (application/octet-stream, attachment)]
This bug report was last modified 5 years and 246 days ago.

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