Fix bug #36474, such that CC Mode quotes work properly in electric-pair-mode

Also finishes the fix for bug #36423.

* lisp/progmodes/cc-mode.el (c-initialize-cc-mode): Add an `eval-after-load'
to set electric-pair-inhibit-predicate for existing CC Mode buffers when
elec-pair.elc gets loaded.
(c-basic-common-init): Set electric-pair-inhibit-predicate when a CC Mode mode
gets initialized.
(c-electric-pair-inhibit-predicate): New function.

1 files changed, 40 insertions, 0 deletions

diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index b45c2e5fd38..98b8385fccb 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -226,6 +226,15 @@ control).  See \"cc-mode.el\" for more info."
             (if (boundp 'c-comment-continuation-stars)
                 (setq c-block-comment-prefix c-comment-continuation-stars))
             (add-hook 'change-major-mode-hook 'c-leave-cc-mode-mode)
+            ;; Connect up with Emacs's electric-pair-mode
+            (eval-after-load "elec-pair"
+              '(when (boundp 'electric-pair-inhibit-predicate)
+                 (dolist (buf (buffer-list))
+                   (with-current-buffer buf
+                     (when c-buffer-is-cc-mode
+                       (make-local-variable 'electric-pair-inhibit-predicate)
+                       (setq electric-pair-inhibit-predicate
+                             #'c-electric-pair-inhibit-predicate))))))
             (setq c-initialization-ok t)
             ;; Connect up with Emacs's electric-indent-mode, for >= Emacs 24.4
             (when (fboundp 'electric-indent-local-mode)
@@ -553,6 +562,17 @@ that requires a literal mode spec at compile time."
   (make-local-variable 'adaptive-fill-regexp)
   (make-local-variable 'fill-paragraph-handle-comment)
 
+  (setq c-buffer-is-cc-mode mode)
+
+  ;; Prepare for the use of `electric-pair-mode'.  Note: if this mode is not
+  ;; yet loaded, `electric-pair-inhibit-predicate' will get set from an
+  ;; `eval-after-load' form in `c-initialize-cc-mode' when elec-pair.elc is
+  ;; loaded.
+  (when (boundp 'electric-pair-inhibit-predicate)
+    (make-local-variable 'electric-pair-inhibit-predicate)
+    (setq electric-pair-inhibit-predicate
+          #'c-electric-pair-inhibit-predicate))
+
   ;; now set their values
   (set (make-local-variable 'parse-sexp-ignore-comments) t)
   (set (make-local-variable 'indent-line-function) 'c-indent-line)
@@ -2255,6 +2275,26 @@ This function is called from `c-common-init', once per mode initialization."
     (c-update-modeline)))
 
 
+;; Connection with Emacs's electric-pair-mode
+(defun c-electric-pair-inhibit-predicate (char)
+  "Return t to inhibit the insertion of a second copy of CHAR.
+
+At the time of call, point is just after the newly inserted CHAR.
+
+When CHAR is \", t will be returned unless the \" is marked with
+a string fence syntax-table text property.  For other characters,
+the default value of `electric-pair-inhibit-predicate' is called
+and its value returned.
+
+This function is the appropriate value of
+`electric-pair-inhibit-predicate' for CC Mode modes, which mark
+invalid strings with such a syntax table text property on the
+opening \" and the next unescaped end of line."
+  (if (eq char ?\")
+      (not (equal (get-text-property (1- (point)) 'syntax-table) '(15)))
+    (funcall (default-value 'electric-pair-inhibit-predicate) char)))
+
+
 ;; Support for C
 
 (defvar c-mode-syntax-table