master c2b79d9148: CC Mode: Don't fontify as types variables with the same names as struct tags

[Alan Mackenzie]

branch: master
commit c2b79d9148f21c3717f1eaa2d37b837b0922b94c
Author: Alan Mackenzie <acm@muc.de>
Commit: Alan Mackenzie <acm@muc.de>

    CC Mode: Don't fontify as types variables with the same names as struct tags
    
    This fixes bug #58534.
    
    * lisp/progmodes/cc-engine.el (c-forward-type): Only regard "struct" 
keywords
    which create self contained types (e.g. C++'s "typename") as creating found
    types.
    
    * lisp/progmodes/cc-langs.el (c-self-contained-typename-kwds
    (c-self-contained-typename-key): New language consts and variable.
---
 lisp/progmodes/cc-engine.el | 13 +++++++++----
 lisp/progmodes/cc-langs.el  | 13 ++++++++++++-
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 223b1e917f..596cccdf48 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -9055,7 +9055,8 @@ multi-line strings (but not C++, for example)."
     (c-forward-<>-arglist t)
     (c-forward-syntactic-ws))
 
-  (let ((start (point)) pos res name-res id-start id-end id-range)
+  (let ((start (point)) pos res name-res id-start id-end id-range
+       post-prefix-pos)
 
     ;; Skip leading type modifiers.  If any are found we know it's a
     ;; prefix of a type.
@@ -9067,6 +9068,7 @@ multi-line strings (but not C++, for example)."
        (c-forward-syntactic-ws)
        (or (eq res 'no-id)
            (setq res 'prefix))))
+    (setq post-prefix-pos (point))
 
     (cond
      ((looking-at c-typeof-key) ; e.g. C++'s "decltype".
@@ -9099,9 +9101,12 @@ multi-line strings (but not C++, for example)."
       (setq name-res (c-forward-name))
       (setq res (not (null name-res)))
       (when (eq name-res t)
-       ;; In many languages the name can be used without the
-       ;; prefix, so we add it to `c-found-types'.
-       (c-add-type pos (point))
+       ;; With some keywords the name can be used without the prefix, so we
+       ;; add the name to `c-found-types' when this is the case.
+       (when (save-excursion
+               (goto-char post-prefix-pos)
+               (looking-at c-self-contained-typename-key))
+         (c-add-type pos (point)))
        (when (and c-record-type-identifiers
                   c-last-identifier-range)
          (c-record-type-id c-last-identifier-range)))
diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index b17718cfd5..6ccd6c30df 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -2294,11 +2294,22 @@ declaration with a type as a default value.  This is 
used only in
 C++ Mode, e.g. \"<typename X = Y>\"."
   t    nil
   c++  '("class" "typename"))
-
 (c-lang-defconst c-template-typename-key
   t (c-make-keywords-re t (c-lang-const c-template-typename-kwds)))
 (c-lang-defvar c-template-typename-key (c-lang-const c-template-typename-key))
 
+(c-lang-defconst c-self-contained-typename-kwds
+  "Keywords where the following name is a type name which can be
+used in declarations without the keyword."
+  t    nil
+  c++  '("typename"))
+
+(c-lang-defconst c-self-contained-typename-key
+  ;; Adorned regexp matching `c-self-contained-typename-key'.
+  t (c-make-keywords-re t (c-lang-const c-self-contained-typename-kwds)))
+(c-lang-defvar c-self-contained-typename-key
+              (c-lang-const c-self-contained-typename-key))
+
 (c-lang-defconst c-type-prefix-kwds
   "Keywords where the following name - if any - is a type name, and
 where the keyword together with the symbol works as a type in