From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Sun, 17 Mar 2019 00:11:45 +0000 (-0400)
Subject: * lisp/subr.el (combine-change-calls-1): Don't combine syntax-ppss flushes
X-Git-Tag: emacs-27.0.90~3401
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=3320fe2deeba6dcc40e934e8a03bef4945c86aff;p=emacs.git

* lisp/subr.el (combine-change-calls-1): Don't combine syntax-ppss flushes
---

diff --git a/lisp/emacs-lisp/syntax.el b/lisp/emacs-lisp/syntax.el
index 11cab1d693d..d09d6c12254 100644
--- a/lisp/emacs-lisp/syntax.el
+++ b/lisp/emacs-lisp/syntax.el
@@ -533,6 +533,11 @@ running the hook."
 
 	      ;; Setup the before-change function if necessary.
 	      (unless (or ppss-cache ppss-last)
+                ;; We should be either the very last function on
+                ;; before-change-functions or the very first on
+                ;; after-change-functions.
+                ;; Note: combine-change-calls-1 needs to be kept in sync
+                ;; with this!
 		(add-hook 'before-change-functions
 			  'syntax-ppss-flush-cache t t))
 
diff --git a/lisp/subr.el b/lisp/subr.el
index 4024c68e68d..6c0ad00afa5 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -3686,7 +3686,7 @@ the specified region.  It must not change
 `before-change-functions' or `after-change-functions'.
 
 Additionally, the buffer modifications of BODY are recorded on
-the buffer's undo list as a single \(apply ...) entry containing
+the buffer's undo list as a single (apply ...) entry containing
 the function `undo--wrap-and-run-primitive-undo'."
   (let ((old-bul buffer-undo-list)
 	(end-marker (copy-marker end t))
@@ -3699,7 +3699,14 @@ the function `undo--wrap-and-run-primitive-undo'."
 	(if (eq buffer-undo-list t)
 	    (setq result (funcall body))
 	  (let (;; (inhibit-modification-hooks t)
-                before-change-functions after-change-functions)
+                (before-change-functions
+                 ;; Ugly Hack: if the body uses syntax-ppss/syntax-propertize
+                 ;; (e.g. via a regexp-search or sexp-movement trigerring
+                 ;; on-the-fly syntax-propertize), make sure that this gets
+                 ;; properly refreshed after subsequent changes.
+                 (if (memq #'syntax-ppss-flush-cache before-change-functions)
+                     '(syntax-ppss-flush-cache)))
+                after-change-functions)
 	    (setq result (funcall body)))
 	  (let ((ap-elt
 		 (list 'apply