bug#23387: 25.0.93; Unicode quote inserted in Python mode outside of strings

[Philipp Stephani <p.stephani2@gmail.com>]

[-- Attachment #1.1: Type: text/plain, Size: 1176 bytes --]

Philipp Stephani <p.stephani2@gmail.com> schrieb am Do., 28. Apr. 2016 um
19:22 Uhr:

> Philipp Stephani <p.stephani2@gmail.com> schrieb am Do., 28. Apr. 2016 um
> 19:11 Uhr:
>
>> Philipp Stephani <p.stephani2@gmail.com> schrieb am Mi., 27. Apr. 2016
>> um 16:16 Uhr:
>>
>>>
>>> emacs -Q
>>> M-x electric-quote-mode
>>> M-x customize-variable RET electric-quote-string, set it to t, save
>>> M-x python-mode
>>> Hit '
>>>
>>> Expected: ' (ASCII apostrophe) is inserted because point is outside a
>>> string
>>> Actual: ’ (Unicode quote) is inserted
>>>
>>> This seems to happen only in Python mode, not in e.g. emacs-lisp-mode.
>>>
>>> Also happens in C++ mode, and probably others.
>>
>
> The root cause is that electric-quote-post-self-insert-function uses
> syntax-ppss to check whether point is in a string or comment. Before it
> makes any replacement, the ASCII apostrophe is still in the buffer, so
> syntax-ppss considers point to be inside a string. It looks like calling
> syntax-ppss with (forward-point -1) as argument instead of (point) should
> fix it, but I'm not sure whether that's the right way.
>

I've attached a patch.

[-- Attachment #1.2: Type: text/html, Size: 2067 bytes --]

[-- Attachment #2: 0001-Fix-insertion-of-Unicode-quotes-in-strings.patch --]
[-- Type: application/octet-stream, Size: 2052 bytes --]

From cd7c17079c7efdd00fadc01c6622db3baab9d48a Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Sat, 30 Apr 2016 12:45:22 +0200
Subject: [PATCH] Fix insertion of Unicode quotes in strings.

* lisp/electric.el (electric-quote-post-self-insert-function): Parse
until before point to fix Bug#23387.
* test/automated/electric-tests.el (electric-quote-string): Add unit
test for electric-quote-string.
---
 lisp/electric.el                 | 5 ++++-
 test/automated/electric-tests.el | 8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/lisp/electric.el b/lisp/electric.el
index ab79943..74b4e91 100644
--- a/lisp/electric.el
+++ b/lisp/electric.el
@@ -444,7 +444,10 @@ electric-quote-post-self-insert-function
     (let ((start
            (if (and comment-start comment-use-syntax)
                (when (or electric-quote-comment electric-quote-string)
-                 (let ((syntax (syntax-ppss)))
+                 ;; Here the quote has already been inserted, so we
+                 ;; might be inside a string.  Therefore use the
+                 ;; position before point for syntactic parsing.
+                 (let ((syntax (save-excursion (syntax-ppss (1- (point))))))
                    (and (or (and electric-quote-comment (nth 4 syntax))
                             (and electric-quote-string (nth 3 syntax)))
                         (nth 8 syntax))))
diff --git a/test/automated/electric-tests.el b/test/automated/electric-tests.el
index 107b2e7..afd7076 100644
--- a/test/automated/electric-tests.el
+++ b/test/automated/electric-tests.el
@@ -584,5 +584,13 @@ autowrapping-7
                   (skip-chars-backward "\"")
                   (mark-sexp -1)))
 
+\f
+;;; Electric quotes
+(define-electric-pair-test electric-quote-string
+  "" "'" :expected-string "'" :expected-point 2
+  :fixture-fn #'electric-quote-local-mode
+  :bindings '((electric-quote-string . t))
+  :test-in-comments nil :test-in-strings nil)
+
 (provide 'electric-tests)
 ;;; electric-tests.el ends here
-- 
2.8.1