Amend c-before-change-check-unbalanced-strings to handle a quote at EOB.

* lisp/progmodes/cc-mode.el (c-before-change-check-unbalanced-strings): Before
going back a sexp from the \n marked with a string-fence syntax-table text
property, check that it is indeed a \n.  If not, simply delete that text
property from the isolated quote, not the quote and the \n which otherwise
delimit an unterminated string.  Should we encounter a double quote marked
with a string-fence syntax-table text property at the end of the last line,
remove that property.

1 files changed, 23 insertions, 16 deletions

diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index 2427191eae0..49c917160c1 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -1121,7 +1121,8 @@ Note that the style variables are always made local to the buffer."
   ;; If BEG or END is inside an unbalanced string, remove the syntax-table
   ;; text property from respectively the start or end of the string.  Also
   ;; extend the region (c-new-BEG c-new-END) as necessary to cope with the
-  ;; change being the insertion of an odd number of quotes.
+  ;; coming change involving the insertion or deletion of an odd number of
+  ;; quotes.
   ;;
   ;; POINT is undefined both at entry to and exit from this function, the
   ;; buffer will have been widened, and match data will have been saved.
@@ -1169,31 +1170,37 @@ Note that the style variables are always made local to the buffer."
                       (c-clear-char-property (1- (point)) 'syntax-table)
                       (not (eq (char-before) ?\")))))
                (eq (char-before) ?\"))
-             (if (eq (char-before (1- (point)))
-                     c-multiline-string-start-char)
-                 (progn
-                   (c-pps-to-string-delim (point-max))
-                   (< (point) (point-max)))
-               (c-pps-to-string-delim (c-point 'eoll))
-               (< (point) (c-point 'eoll))))))
+             (progn
+               (c-pps-to-string-delim (point-max))
+               (< (point) (point-max))))))
       (setq c-new-END (max (point) c-new-END)))
 
      ((< c-new-END (point-max))
       (goto-char (1+ c-new-END))        ; might be a newline.
       ;; In the following regexp, the initial \n caters for a newline getting
       ;; joined to a preceding \ by the removal of what comes between.
-      (re-search-forward "\n?\\(\\\\\\(.\\|\n\\|\r\\)\\|[^\\\n\r]\\)*" nil t)
+      (re-search-forward "[\n\r]?\\(\\\\\\(.\\|\n\\|\r\\)\\|[^\\\n\r]\\)*"
+                         nil t)
       ;; We're at an EOLL or point-max.
       (setq c-new-END (min (1+ (point)) (point-max)))
       ;; FIXME!!!  Write a clever comment here.
       (goto-char c-new-END)
-      (when (equal (c-get-char-property (1- (point)) 'syntax-table) '(15))
-        (backward-sexp)
-        (c-clear-char-property (1- c-new-END) 'syntax-table)
-        (c-clear-char-property (point) 'syntax-table)))
-
-     (t (if (memq (char-before c-new-END) c-string-delims)
-            (c-clear-char-property (1- c-new-END) 'syntax-table))))
+      (if (equal (c-get-char-property (1- (point)) 'syntax-table) '(15))
+          (if (memq (char-before) '(?\n ?\r))
+              ;; Normally terminated invalid string.
+              (progn
+                (backward-sexp)
+                (c-clear-char-property (1- c-new-END) 'syntax-table)
+                (c-clear-char-property (point) 'syntax-table))
+            ;; Opening " at EOB.
+            (c-clear-char-property (1- (point)) 'syntax-table))
+        (if (c-search-backward-char-property 'syntax-table '(15) c-new-BEG)
+            ;; Opening " on last line of text (without EOL).
+            (c-clear-char-property (point) 'syntax-table))))
+
+     (t (goto-char c-new-END)
+        (if (c-search-backward-char-property 'syntax-table '(15) c-new-BEG)
+            (c-clear-char-property (point) 'syntax-table))))
 
     (when (eq end-literal-type 'string)
       (c-clear-char-property (1- (cdr end-limits)) 'syntax-table))