GNU bug report logs - #44724
Uninitialised variables in syntax.c cause trouble.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Alan Mackenzie <acm <at> muc.de>
To: bug-gnu-emacs <at> gnu.org
Subject: Uninitialised variables in syntax.c cause trouble.
Date: Wed, 18 Nov 2020 17:38:34 +0000

Hello, Emacs.

On the master branch.

In src/syntax.c, there are several uninitialised static variables, one of
which is find_start_value.

It is used in function find_defun_start before being initialised.  The
first use is at L.14 of the function, this:

      && pos >= find_start_value

.  This has the effect of causing a certain (forward-comment -1) (which
calls back_comment, which calls find_defun_start) to fail.

In my test setup (I am writing tests for syntax.c), find_start_value's
value at loading time was randomly 1270, which was spuriously inside the
comment I was trying to scan backwards over.  back_comment thus failed to
recognise the comment, and returned failed.

All these variables need initialising to something if the code in
syntax.c is to work properly.

-- 
Alan Mackenzie (Nuremberg, Germany).

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