master 81fe899: CC Mode: Move the handling of keyword auto into type handling for C++.

[Alan Mackenzie]

branch: master
commit 81fe8990c0e4c0980e599b6ec9cad6dcb945275a
Author: Alan Mackenzie <acm@muc.de>
Commit: Alan Mackenzie <acm@muc.de>

    CC Mode: Move the handling of keyword auto into type handling for C++.
    
    This should allow auto, const, static, ... to be in any order.
    
    * lisp/progmodes/cc-engine.el (c-forward-type): New return value 'no-id for
    when auto precludes the parsing of a type identifier.  Adapt processing for
    this.
    (c-forward-decl-or-cast-1): Use the new facility from c-forward-type.
    
    * lisp/progmodes/cc-langs.el (c-type-modifier-prefix-kwds): Insert the value
    of c-no-type-kwds into the value.
    (c-no-type-kwds, c-no-type-key): New lang consts/vars, basically "auto".
    (c-typeless-decl-kwds, c-modifier-kwds): Remove "auto" from the C++ value.
---
 lisp/progmodes/cc-engine.el | 71 +++++++++++++++++++++++++--------------------
 lisp/progmodes/cc-langs.el  | 18 ++++++++++--
 2 files changed, 55 insertions(+), 34 deletions(-)

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 4e336c0..1649f50 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -8426,6 +8426,7 @@ comment at the start of cc-engine.el for more info."
   ;;   o - 'found if it's a type that matches one in `c-found-types';
   ;;   o - 'maybe if it's an identifier that might be a type;
   ;;   o - 'decltype if it's a decltype(variable) declaration; - or
+  ;;   o - 'no-id if "auto" precluded parsing a type identifier.
   ;;   o -  nil if it can't be a type (the point isn't moved then).
   ;;
   ;; The point is assumed to be at the beginning of a token.
@@ -8450,9 +8451,12 @@ comment at the start of cc-engine.el for more info."
     ;; prefix of a type.
     (when c-opt-type-modifier-prefix-key ; e.g. "const" "volatile", but NOT 
"typedef"
       (while (looking-at c-opt-type-modifier-prefix-key)
+       (when (looking-at c-no-type-key)
+         (setq res 'no-id))
        (goto-char (match-end 1))
        (c-forward-syntactic-ws)
-       (setq res 'prefix)))
+       (or (eq res 'no-id)
+           (setq res 'prefix))))
 
     (cond
      ((looking-at c-typeof-key) ; e.g. C++'s "decltype".
@@ -8503,28 +8507,30 @@ comment at the start of cc-engine.el for more info."
        (setq res t))
       (unless res (goto-char start)))  ; invalid syntax
 
-     ((progn
-       (setq pos nil)
-       (if (looking-at c-identifier-start)
-           (save-excursion
-             (setq id-start (point)
-                   name-res (c-forward-name))
-             (when name-res
-               (setq id-end (point)
-                     id-range c-last-identifier-range))))
-       (and (cond ((looking-at c-primitive-type-key)
-                   (setq res t))
-                  ((c-with-syntax-table c-identifier-syntax-table
-                     (looking-at c-known-type-key))
-                   (setq res 'known)))
-            (or (not id-end)
-                (>= (save-excursion
-                      (save-match-data
-                        (goto-char (match-end 1))
-                        (c-forward-syntactic-ws)
-                        (setq pos (point))))
-                    id-end)
-                (setq res nil))))
+     ((and
+       (not (eq res 'no-id))
+       (progn
+        (setq pos nil)
+        (if (looking-at c-identifier-start)
+            (save-excursion
+              (setq id-start (point)
+                    name-res (c-forward-name))
+              (when name-res
+                (setq id-end (point)
+                      id-range c-last-identifier-range))))
+        (and (cond ((looking-at c-primitive-type-key)
+                    (setq res t))
+                   ((c-with-syntax-table c-identifier-syntax-table
+                      (looking-at c-known-type-key))
+                    (setq res 'known)))
+             (or (not id-end)
+                 (>= (save-excursion
+                       (save-match-data
+                         (goto-char (match-end 1))
+                         (c-forward-syntactic-ws)
+                         (setq pos (point))))
+                     id-end)
+                 (setq res nil)))))
       ;; Looking at a primitive or known type identifier.  We've
       ;; checked for a name first so that we don't go here if the
       ;; known type match only is a prefix of another name.
@@ -8599,7 +8605,7 @@ comment at the start of cc-engine.el for more info."
             (goto-char start)
             (setq res nil)))))
 
-    (when res
+    (when (not (memq res '(nil no-id)))
       ;; Skip trailing type modifiers.  If any are found we know it's
       ;; a type.
       (when c-opt-type-modifier-key
@@ -9452,12 +9458,11 @@ This function might do hidden buffer changes."
 
          (when (setq found-type (c-forward-type t)) ; brace-block-too
            ;; Found a known or possible type or a prefix of a known type.
-           (when (and (c-major-mode-is 'c++-mode) ; C++11 style "auto"?
-                      (eq prev-kwd-sym (c-keyword-sym "auto"))
-                      (looking-at "[=(]")) ; FIXME!!! proper regexp.
-             (setq new-style-auto t)
-             (setq found-type nil)
-             (goto-char start))        ; position of foo in "auto foo"
+           (when (and (eq found-type 'no-id)
+                      (save-excursion
+                        (and (c-forward-name) ; over the identifier
+                      (looking-at "[=(]")))) ; FIXME!!! proper regexp.
+             (setq new-style-auto t))  ; position of foo in "auto foo"
 
            (when at-type
              ;; Got two identifiers with nothing but whitespace
@@ -9540,7 +9545,7 @@ This function might do hidden buffer changes."
            ;; over all specifiers and type identifiers.  The reason
            ;; to do this for a known type prefix is to make things
            ;; like "unsigned INT16" work.
-           (and found-type (not (eq found-type t))))))
+           (and found-type (not (memq found-type '(t no-id)))))))
 
     (cond
      ((eq at-type t)
@@ -9560,6 +9565,10 @@ This function might do hidden buffer changes."
       ;; followed by another type.
       (setq at-type t))
 
+     ((eq at-type 'no-id)
+      ;; For an auto type, we assume we definitely have a type construct.
+      (setq at-type t))
+
      ((not at-type)
       ;; Got no type but set things up to continue anyway to handle
       ;; the various cases when a declaration doesn't start with a
diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index 13e70a3..80c461c 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -2121,7 +2121,9 @@ fontified with the keyword face and not the type face."
   t    nil
   c    '("const" "restrict" "volatile")
   c++  '("const" "noexcept" "volatile")
-  objc '("const" "volatile"))
+  objc '("const" "volatile")
+  t    (append (c-lang-const c-no-type-kwds)
+              (c-lang-const c-type-modifier-prefix-kwds)))
 
 (c-lang-defconst c-opt-type-modifier-prefix-key
   ;; Adorned regexp matching `c-type-modifier-prefix-kwds', or nil in
@@ -2348,6 +2350,16 @@ will be handled."
   t (c-make-keywords-re t (c-lang-const c-using-kwds)))
 (c-lang-defvar c-using-key (c-lang-const c-using-key))
 
+(c-lang-defconst c-no-type-kwds
+  "Keywords which remove the need to specify a type in declarations"
+  t nil
+  c++ '("auto"))
+
+(c-lang-defconst c-no-type-key
+  ;; Regexp matching an entry from `c-no-type-kwds'
+  t (c-make-keywords-re t (c-lang-const c-no-type-kwds)))
+(c-lang-defvar c-no-type-key (c-lang-const c-no-type-key))
+
 (c-lang-defconst c-typeless-decl-kwds
   "Keywords introducing declarations where the (first) identifier
 \(declarator) follows directly after the keyword, without any type.
@@ -2361,7 +2373,6 @@ will be handled."
   ;; {...}").
   t    (append (c-lang-const c-class-decl-kwds)
               (c-lang-const c-brace-list-decl-kwds))
-  c++  (append (c-lang-const c-typeless-decl-kwds) '("auto")) ; C++11.
   ;; Note: "manages" for CORBA CIDL clashes with its presence on
   ;; `c-type-list-kwds' for IDL.
   idl  (append (c-lang-const c-typeless-decl-kwds)
@@ -2396,7 +2407,8 @@ If any of these also are on `c-type-list-kwds', 
`c-ref-list-kwds',
 `c-<>-type-kwds', or `c-<>-arglist-kwds' then the associated clauses
 will be handled."
   t    nil
-  (c c++) '("auto" "extern" "inline" "register" "static")
+  (c c++) '("extern" "inline" "register" "static")
+  c    (append '("auto") (c-lang-const c-modifier-kwds))
   c++  (append '("constexpr" "explicit" "friend" "mutable" "template"
                 "thread_local" "virtual")
               ;; "using" is now handled specially (2020-09-14).