master cc9ac56081: CC Mode: Prevent rapid alternation of fontification of "found types"

[Alan Mackenzie]

branch: master
commit cc9ac56081719f553b3e7758c391c595c3fa4eaf
Author: Alan Mackenzie <acm@muc.de>
Commit: Alan Mackenzie <acm@muc.de>

    CC Mode: Prevent rapid alternation of fontification of "found types"
    
    This fixes bug #52863.
    
    * lisp/progmodes/cc-engine.el (c-forward-decl-or-cast-1): When a new type is
    found, postpone entering it into c-found-types (and thus triggering the
    fontification of that type throughout the buffer) until the end of the
    function, when we're sure that the "type" found actually is a type.
---
 lisp/progmodes/cc-engine.el | 38 +++++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index d289148874..11f3668137 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -9937,6 +9937,10 @@ This function might do hidden buffer changes."
        ;; Set when we have encountered a keyword (e.g. "extern") which
        ;; causes the following declaration to be treated as though top-level.
        make-top
+       ;; A list of found types in this declaration.  This is an association
+       ;; list, the car being the buffer position, the cdr being the
+       ;; identifier.
+       found-type-list
        ;; Save `c-record-type-identifiers' and
        ;; `c-record-ref-identifiers' since ranges are recorded
        ;; speculatively and should be thrown away if it turns out
@@ -10006,10 +10010,17 @@ This function might do hidden buffer changes."
                ;; If the previous identifier is a found type we
                ;; record it as a real one; it might be some sort of
                ;; alias for a prefix like "unsigned".
-               (save-excursion
-                 (goto-char type-start)
-                 (let ((c-promote-possible-types t))
-                   (c-forward-type))))
+               ;; We postpone entering the new found type into c-found-types
+               ;; until we are sure of it, thus preventing rapid alternation
+               ;; of the fontification of the token throughout the buffer.
+               (push (cons type-start
+                           (buffer-substring-no-properties
+                            type-start
+                            (save-excursion
+                              (goto-char type-start)
+                              (c-end-of-token)
+                              (point))))
+                     found-type-list))
 
              ;; Signal a type declaration for "struct foo {".
              (when (and backup-at-type-decl
@@ -10255,13 +10266,10 @@ This function might do hidden buffer changes."
                   (when (eq at-type 'found)
                     ;; Remove the ostensible type from the found types list.
                     (when type-start
-                      (c-unfind-type
-                       (buffer-substring-no-properties
-                        type-start
-                        (save-excursion
-                          (goto-char type-start)
-                          (c-end-of-token)
-                          (point)))))
+                      (let ((discard-t (assq type-start found-type-list)))
+                        (when discard-t
+                          (setq found-type-list
+                                (remq discard-t found-type-list)))))
                     t))
               ;; The token which we assumed to be a type is actually the
               ;; identifier, and we have no explicit type.
@@ -10875,6 +10883,14 @@ This function might do hidden buffer changes."
        ;; interactive refontification.
        (c-put-c-type-property (point) 'c-decl-arg-start))
 
+      ;; Enter all the found types into `c-found-types'.
+      (when found-type-list
+       (save-excursion
+         (let ((c-promote-possible-types t))
+           (dolist (ft found-type-list)
+             (goto-char (car ft))
+             (c-forward-type)))))
+
       ;; Record the type's coordinates in `c-record-type-identifiers' for
       ;; later fontification.
       (when (and c-record-type-identifiers at-type ;; (not (eq at-type t))