Correct calculation of CC Mode's font-lock region.

* cc-mode.el (c-fl-decl-start): Renamed from c-set-fl-decl-start.
* Change
signature such that nil is returned when no declaration is found.
(c-change-expand-fl-region): Renamed from c-change-set-fl-decl-start.
This now also handles expanding the font lock region to whole lines.
(c-context-expand-fl-region): Renamed from c-context-set-fl-decl-start.
This now also handles expanding the font lock region to whole lines.
(c-font-lock-fontify-region): When a change font lock region is
spuriously enlarged to the beginning-of-line by jit-lock, fontify the
extra bit separately from the region calculated by CC Mode.
(c-extend-after-change-region): Explicitly apply 'fontified properties
to
the extended bits of the font lock region.

* cc-langs.el (c-before-font-lock-functions)
(c-before-context-fontification-functions): Use new names for existing
functions (see above).

3 files changed, 106 insertions, 35 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 69d9ab9f977..649e8849732 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,26 @@
+2015-03-30  Alan Mackenzie  <acm@muc.de>
+
+        Correct calculation of CC Mode's font-lock region.
+
+        * progmodes/cc-mode.el (c-fl-decl-start): Renamed from
+        c-set-fl-decl-start.  Change signature such that nil is returned
+        when no declaration is found.
+        (c-change-expand-fl-region): Renamed from
+        c-change-set-fl-decl-start.  This now also handles expanding the
+        font lock region to whole lines.
+        (c-context-expand-fl-region): Renamed from
+        c-context-set-fl-decl-start.  This now also handles expanding the
+        font lock region to whole lines.
+        (c-font-lock-fontify-region): When a change font lock region is
+        spuriously enlarged to the beginning-of-line by jit-lock, fontify
+        the extra bit separately from the region calculated by CC Mode.
+        (c-extend-after-change-region): Explicitly apply 'fontified
+        properties to the extended bits of the font lock region.
+
+        * progmodes/cc-langs.el (c-before-font-lock-functions)
+        (c-before-context-fontification-functions): Use new names for
+        existing functions (see above).
+
 2015-03-30  Richard Ryniker  <ryniker@alum.mit.edu>  (tiny change)
 
         * mail/sendmail.el (sendmail-send-it): Do not attempt to switch
diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index 4d16a9b9d33..c7b24e185c2 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -497,7 +497,7 @@ parameters \(point-min) and \(point-max).")
   ;; The value here may be a list of functions or a single function.
   t 'c-change-set-fl-decl-start
   (c c++ objc) '(c-neutralize-syntax-in-and-mark-CPP
-                 c-change-set-fl-decl-start)
+                 c-change-expand-fl-region)
   awk 'c-awk-extend-and-syntax-tablify-region)
 (c-lang-defvar c-before-font-lock-functions
                (let ((fs (c-lang-const c-before-font-lock-functions)))
@@ -524,7 +524,7 @@ parameters \(point-min), \(point-max) and <buffer size>.")
 
 (c-lang-defconst c-before-context-fontification-functions
   awk nil
-  t 'c-context-set-fl-decl-start)
+  t 'c-context-expand-fl-region)
   ;; For documentation see the following c-lang-defvar of the same name.
   ;; The value here may be a list of functions or a single function.
 (c-lang-defvar c-before-context-fontification-functions
diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index f84f4ae2c20..c95e8a91555 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -1148,11 +1148,11 @@ Note that the style variables are always made local to the buffer."
                   (funcall fn beg end old-len))
                 c-before-font-lock-functions))))))
 
-(defun c-set-fl-decl-start (pos)
+(defun c-fl-decl-start (pos)
   ;; If the beginning of the line containing POS is in the middle of a "local"
   ;; declaration (i.e. one which does not start outside of braces enclosing
   ;; POS, such as a struct), return the beginning of that declaration.
-  ;; Otherwise return POS.  Note that declarations, in this sense, can be
+  ;; Otherwise return nil.  Note that declarations, in this sense, can be
   ;; nested.
   ;;
   ;; This function is called indirectly from font locking stuff - either from
@@ -1189,29 +1189,50 @@ Note that the style variables are always made local to the buffer."
                               (1- (point)) 'syntax-table)
                              c-<-as-paren-syntax)))))
          (not (bobp)))
-      (backward-char))
-    new-pos))                           ; back over (, [, <.
-
-(defun c-change-set-fl-decl-start (_beg _end _old-len)
-  ;; Set c-new-BEG to the beginning of a "local" declaration if it('s BOL) is
-  ;; inside one.  This is called from an after-change-function, but the
-  ;; parameters BEG END and OLD-LEN are ignored.  See `c-set-fl-decl-start'
-  ;; for the detailed functionality.
-  (if font-lock-mode
-      (setq c-new-BEG (c-set-fl-decl-start c-new-BEG))))
-
-(defun c-context-set-fl-decl-start (beg end)
-  ;; Return a cons (NEW-BEG . END), where NEW-BEG is the beginning of a
-  ;; "local" declaration (BOL at) NEW is inside or BEG.  See
-  ;; `c-set-fl-decl-start' for the detailed functionality.
-  (cons (c-set-fl-decl-start beg) end))
+      (backward-char))                  ; back over (, [, <.
+    (and (/= new-pos pos) new-pos)))
+
+(defun c-change-expand-fl-region (beg end old-len)
+  ;; Expand the region (c-new-BEG c-new-END) to an after-change font-lock
+  ;; region.  This will usually be the smallest sequence of whole lines
+  ;; containing `c-new-BEG' and `c-new-END', but if `c-new-BEG' is in a
+  ;; "local" declaration (see `c-fl-decl-start') the beginning of this is used
+  ;; as the lower bound.
+  ;;
+  ;; This is called from an after-change-function, but the parameters BEG END
+  ;; and OLD-LEN are not used.
+   (if font-lock-mode
+       (setq c-new-BEG
+             (or (c-fl-decl-start c-new-BEG) (c-point 'bol c-new-BEG))
+             c-new-END (c-point 'bonl c-new-END))))
+
+(defun c-context-expand-fl-region (beg end)
+  ;; Return a cons (NEW-BEG . NEW-END), where NEW-BEG is the beginning of a
+  ;; "local" declaration containing BEG (see `c-fl-decl-start') or BOL BEG is
+  ;; in.  NEW-END is beginning of the line after the one END is in.
+  (cons (or (c-fl-decl-start beg) (c-point 'bol beg))
+        (c-point 'bonl end)))
+
+(defun c-before-context-fl-expand-region (beg end)
+  ;; Expand the region (BEG END) as specified by
+  ;; `c-before-context-fontification-functions'.  Return a cons of the bounds
+  ;; of the new region.
+  (save-restriction
+    (widen)
+    (save-excursion
+      (let ((new-beg beg) (new-end end) new-region)
+        (mapc (lambda (fn)
+                (setq new-region (funcall fn new-beg new-end))
+                (setq new-beg (car new-region) new-end (cdr new-region)))
+              c-before-context-fontification-functions)
+        new-region))))
 
 (defun c-font-lock-fontify-region (beg end &optional verbose)
   ;; Effectively advice around `font-lock-fontify-region' which extends the
   ;; region (BEG END), for example, to avoid context fontification chopping
-  ;; off the start of the context.  Do not do anything if it's already been
-  ;; done (i.e. from an after-change fontification.  An example (C++) where
-  ;; this used to happen is this:
+  ;; off the start of the context.  Do not extend the region if it's already
+  ;; been done (i.e. from an after-change fontification.  An example (C++)
+  ;; where the chopping off used to happen is this:
   ;;
   ;;     template <typename T>
   ;;
@@ -1220,17 +1241,39 @@ Note that the style variables are always made local to the buffer."
   ;; 
   ;; Type a space in the first blank line, and the fontification of the next
   ;; line was fouled up by context fontification.
-  (let ((new-beg beg) (new-end end) new-region case-fold-search
-        open-paren-in-column-0-is-defun-start)
-    (if c-in-after-change-fontification
-        (setq c-in-after-change-fontification nil)
-      (save-restriction
-        (widen)
-        (save-excursion
-          (mapc (lambda (fn)
-                  (setq new-region (funcall fn new-beg new-end))
-                  (setq new-beg (car new-region)  new-end (cdr new-region)))
-                c-before-context-fontification-functions))))
+  (let (new-beg new-end new-region case-fold-search
+                open-paren-in-column-0-is-defun-start)
+    (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)))
     (funcall (default-value 'font-lock-fontify-region-function)
              new-beg new-end verbose)))
 
@@ -1277,7 +1320,7 @@ This function is called from `c-common-init', once per mode initialization."
 ;; Emacs 22 and later.
 (defun c-extend-after-change-region (_beg _end _old-len)
   "Extend the region to be fontified, if necessary."
-  ;; Note: the parameters are ignored here.  This somewhat indirect
+  ;; Note: the parameter OLD-LEN is ignored here.  This somewhat indirect
   ;; implementation exists because it is minimally different from the
   ;; stand-alone CC Mode which, lacking
   ;; font-lock-extend-after-change-region-function, is forced to use advice
@@ -1286,6 +1329,11 @@ This function is called from `c-common-init', once per mode initialization."
   ;; Of the seven CC Mode languages, currently (2009-05) only C, C++, Objc
   ;; (the languages with #define) and AWK Mode make non-null use of this
   ;; function.
+  (when (eq font-lock-support-mode 'jit-lock-mode)
+    (if (< c-new-BEG beg)
+        (put-text-property c-new-BEG beg 'fontified nil))
+    (if (> c-new-END end)
+        (put-text-property end c-new-END 'fontified nil)))
   (cons c-new-BEG c-new-END))
 
 ;; Emacs < 22 and XEmacs