Subject: electric-pair-mode fails to balance in certain cases

From: Dario Gjorgjevski <[email-masked]>
Date: Thu, 30 May 2019 17:11:31 +0200

Consider the following text in html-mode with electric-pair-mode turned
on and electric-pair-skip-self set to electric-pair-default-skip-self:

         <|>

(Take | to denote point.)  In this situation, the expected result of
attempting to insert > is to skip over the one immediately after point,
i.e., end up with <>|.  However, what we get instead is <>|>.  Only if
we *now* attempt to insert >, we end up with <>>|, which doesn't make
any sense.

The same behavior is observed with ordinary parentheses in html-mode,
too.

>From my debugging, the culprit seems to be an unnecessary (or mistaken?)
use of electric-pair--with-uncached-syntax.  I am not sure *why* exactly
it happens, and would appreciate further insight.

The patch shown below fixes the issue.

diff --git a/lisp/elec-pair.el b/lisp/elec-pair.el
index 5fb9d751e2..6450d02c9e 100644
--- a/lisp/elec-pair.el
+++ b/lisp/elec-pair.el
@@ -325,11 +325,9 @@ electric-pair--balance-info
                         (cond ((< direction 0)
                                (condition-case nil
                                    (eq (char-after pos)
-                                       (electric-pair--with-uncached-syntax
-                                           (table)
-                                         (matching-paren
-                                          (char-before
-                                           (scan-sexps (point) 1)))))
+                                       (matching-paren
+                                        (char-before
+                                         (scan-sexps (point) 1))))
                                  (scan-error nil)))
                               (t
                                ;; In this case, no need to use

-- 
Dario Gjorgjevski :: <[email-masked]>
                  :: 744A 4F0B 4F1C 9371
                  :: +48 1525 8666837