Widen around c-font-lock-fontify-region. This fixes bug #38049.

* lisp/progmodes/cc-mode (c-font-lock-fontify-region): Widen in this function,
to ensure that the CC Mode font locking mechanism can examine characters
outside the given region.

1 files changed, 40 insertions, 38 deletions

diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index 6bdfb170f1b..73160fc7a42 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -2232,44 +2232,46 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
   ;;
   ;; Type a space in the first blank line, and the fontification of the next
   ;; line was fouled up by context fontification.
-  (let (new-beg new-end new-region case-fold-search)
-    (if (and c-in-after-change-fontification
-             (< beg c-new-END) (> end c-new-BEG))
-        ;; Region and the latest after-change fontification region overlap.
-        ;; Determine the upper and lower bounds of our adjusted region
-        ;; separately.
-        (progn
-          (if (<= beg c-new-BEG)
-              (setq c-in-after-change-fontification nil))
-          (setq new-beg
-                (if (and (>= beg (c-point 'bol c-new-BEG))
-                         (<= beg c-new-BEG))
-                    ;; Either jit-lock has accepted `c-new-BEG', or has
-                    ;; (probably) extended the change region spuriously to
-                    ;; BOL, which position likely has a syntactically
-                    ;; different position.  To ensure correct fontification,
-                    ;; we start at `c-new-BEG', assuming any characters to the
-                    ;; left of `c-new-BEG' on the line do not require
-                    ;; fontification.
-                    c-new-BEG
-                  (setq new-region (c-before-context-fl-expand-region beg end)
-                        new-end (cdr new-region))
-                  (car new-region)))
-          (setq new-end
-                (if (and (>= end (c-point 'bol c-new-END))
-                         (<= end c-new-END))
-                    c-new-END
-                  (or new-end
-                      (cdr (c-before-context-fl-expand-region beg end))))))
-      ;; Context (etc.) fontification.
-      (setq new-region (c-before-context-fl-expand-region beg end)
-            new-beg (car new-region)  new-end (cdr new-region)))
-    (c-save-buffer-state nil
-      (unwind-protect
-          (progn (c-restore-string-fences new-beg new-end)
-                 (funcall (default-value 'font-lock-fontify-region-function)
-                          new-beg new-end verbose))
-        (c-clear-string-fences)))))
+  (save-restriction
+    (widen)
+    (let (new-beg new-end new-region case-fold-search)
+      (if (and c-in-after-change-fontification
+               (< beg c-new-END) (> end c-new-BEG))
+          ;; Region and the latest after-change fontification region overlap.
+          ;; Determine the upper and lower bounds of our adjusted region
+          ;; separately.
+          (progn
+            (if (<= beg c-new-BEG)
+                (setq c-in-after-change-fontification nil))
+            (setq new-beg
+                  (if (and (>= beg (c-point 'bol c-new-BEG))
+                           (<= beg c-new-BEG))
+                      ;; Either jit-lock has accepted `c-new-BEG', or has
+                      ;; (probably) extended the change region spuriously to
+                      ;; BOL, which position likely has a syntactically
+                      ;; different position.  To ensure correct fontification,
+                      ;; we start at `c-new-BEG', assuming any characters to the
+                      ;; left of `c-new-BEG' on the line do not require
+                      ;; fontification.
+                      c-new-BEG
+                    (setq new-region (c-before-context-fl-expand-region beg end)
+                          new-end (cdr new-region))
+                    (car new-region)))
+            (setq new-end
+                  (if (and (>= end (c-point 'bol c-new-END))
+                           (<= end c-new-END))
+                      c-new-END
+                    (or new-end
+                        (cdr (c-before-context-fl-expand-region beg end))))))
+        ;; Context (etc.) fontification.
+        (setq new-region (c-before-context-fl-expand-region beg end)
+              new-beg (car new-region)  new-end (cdr new-region)))
+      (c-save-buffer-state nil
+        (unwind-protect
+            (progn (c-restore-string-fences new-beg new-end)
+                   (funcall (default-value 'font-lock-fontify-region-function)
+                            new-beg new-end verbose))
+          (c-clear-string-fences))))))
 
 (defun c-after-font-lock-init ()
   ;; Put on `font-lock-mode-hook'.  This function ensures our after-change