Merge from origin/emacs-26

5a7451c CC Mode: stop wrongly recognizing "func(a * 9)" as "pointer t...
b0ed9d1 * lisp/emacs-lisp/cursor-sensor.el: Add motivation

2 files changed, 27 insertions, 2 deletions

diff --git a/lisp/emacs-lisp/cursor-sensor.el b/lisp/emacs-lisp/cursor-sensor.el
index 21c48f830f2..6c33d04dedd 100644
--- a/lisp/emacs-lisp/cursor-sensor.el
+++ b/lisp/emacs-lisp/cursor-sensor.el
@@ -38,6 +38,27 @@
 ;; called just before redisplay happens, according to the movement of
 ;; the cursor since the last redisplay.
 
+;;;; Motivation
+
+;; The old properties were very problematic in practice because they
+;; operate at a much lower level and hence affect all motion
+;; *functions* like goto-char, forward-char, ... hence breaking
+;; invariants like:
+;;
+;;    (forward-char N) == (progn (forward-char N1) (forward-char (- N N1)))
+;;    (point) == (progn (forward-char N) (forward-char -N) (point))
+;;    (+ N (point)) == (progn (forward-char N) (point))
+;;
+;; The problems would usually show up due to interaction between
+;; unrelated code working in the same buffer, where one code used those
+;; properties and the other (unknowingly) assumed those aren't used.
+;; In practice a *lot* of code assumes there's no such funny business.
+;;
+;; Worse: all(?) packages using those properties don't actually want those
+;; properties to affect motion at such a low-level, they only want to
+;; affect the overall effect of commands, but not the effect of every
+;; single point-motion that a given command happened to use internally.
+
 ;;; Code:
 
 ;;;###autoload
diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 376d0bb3d3a..d71a8299cf6 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -8550,6 +8550,8 @@ comment at the start of cc-engine.el for more info."
           got-parens
           ;; True if there is an identifier in the declarator.
           got-identifier
+          ;; True if we find a number where an identifier was expected.
+          got-number
           ;; True if there's a non-close-paren match of
           ;; `c-type-decl-suffix-key'.
           got-suffix
@@ -8627,7 +8629,9 @@ comment at the start of cc-engine.el for more info."
           (and (looking-at c-identifier-start)
                (setq pos (point))
                (setq got-identifier (c-forward-name))
-               (setq name-start pos)))
+               (setq name-start pos))
+          (when (looking-at "[0-9]")
+            (setq got-number t))) ; We've probably got an arithmetic expression.
 
       ;; Skip over type decl suffix operators and trailing noise macros.
       (while
@@ -9101,7 +9105,7 @@ comment at the start of cc-engine.el for more info."
 
            ;; CASE 18
            (when (and (not (memq context '(nil top)))
-                      (or got-prefix
+                      (or (and got-prefix (not got-number))
                           (and (eq context 'decl)
                                (not c-recognize-paren-inits)
                                (or got-parens got-suffix))))