Package: emacs;
Reported by: Alan Mackenzie <acm <at> muc.de>
Date: Sat, 8 Jun 2019 13:18:01 UTC
Severity: normal
Tags: wontfix
Done: Alan Mackenzie <acm <at> muc.de>
Bug is archived. No further changes may be made.
View this message in rfc822 format
From: Alan Mackenzie <acm <at> muc.de> To: 36136 <at> debbugs.gnu.org Cc: Stefan Monnier <monnier <at> iro.umontreal.ca> Subject: bug#36136: [PATCH]: Re: bug#36136: syntax-ppss fails to invalidate its cache on changes to syntax-table text properties Date: Sun, 9 Jun 2019 18:39:12 +0000
On Sat, Jun 08, 2019 at 13:17:24 +0000, Alan Mackenzie wrote:
> Hello, Emacs.
> The syntax-ppss cache is not invalidated when syntax-table text
> properties are set or cleared. This is because the invalidation
> function, syntax-ppss-flush-cache is invoked only as a before-change
> function, but typical (?all) syntax-table property changes happen when
> before-change-functions is inactive.
> This is a bug.
> In my debugging of a CC Mode scenario, a buffer change causes a
> syntax-table text property change at an earlier part of the buffer. This
> is to do with the change making previously non-matching C++ raw string
> identifiers match up. Font lock follows the syntax-ppss state, which
> spuriously records that the end part of the buffer is still in a string.
> Hence the non-string part of the buffer is still fontified with
> font-lock-string-face.
> Suggested fix: the functions set_properties, add_properties,
> remove_properties in textprop.c should check for changes to,
> specifically, syntax-table properties. When these changes are detected,
> a hook called something like syntax-table-props-change-alert-hook should
> be called (with some appropriate position parameters, tbd).
> syntax-ppss-flush-cache will be added to this hook.
> --
> Alan Mackenzie (Nuremberg, Germany).
The following patch is simpler than my first proposal, following
feedback from Eli. It works for me.
Stefan, could you look at this, please?
Make syntax-ppss react to changes in syntax-table text properties
In particular, it trims its cache to the point of such a change. This fixes
bug #36136.
* src/textprop.c (syntax-propertize--done): New buffer local variable.
(set_properties, add_properties, remove_properties): when a syntax-table text
property is being changed, reduce syntax-propertize--done to the buffer
position.
* lisp/emacs-lisp/syntax.el (syntax-ppss--trim-cache): New function extracted
from syntax-ppss-flush-cache.
(syntax-ppss-flush-cache): Now only modifies syntax-propertize--done and
syntax-ppss--done.
(syntax-ppss): Calls syntax-ppss--trim-cache and sets syntax-propertize--done.
diff --git a/lisp/emacs-lisp/syntax.el b/lisp/emacs-lisp/syntax.el
index 9c6d5b5829..6ca27d8e83 100644
--- a/lisp/emacs-lisp/syntax.el
+++ b/lisp/emacs-lisp/syntax.el
@@ -404,13 +404,10 @@ syntax-ppss-narrow
(defvar-local syntax-ppss-narrow-start nil
"Start position of the narrowing for `syntax-ppss-narrow'.")
-(define-obsolete-function-alias 'syntax-ppss-after-change-function
- #'syntax-ppss-flush-cache "27.1")
-(defun syntax-ppss-flush-cache (beg &rest ignored)
- "Flush the cache of `syntax-ppss' starting at position BEG."
- ;; Set syntax-propertize to refontify anything past beg.
- (setq syntax-propertize--done (min beg syntax-propertize--done))
- ;; Flush invalid cache entries.
+(defun syntax-ppss--trim-cache (beg)
+ "Flush the cache specific to `syntax-ppss' from position BEG.
+
+This doesn't include the cache for `syntax-propertize'."
(dolist (cell (list syntax-ppss-wide syntax-ppss-narrow))
(pcase cell
(`(,last . ,cache)
@@ -432,8 +429,16 @@ syntax-ppss-flush-cache
;; (unless cache
;; (remove-hook 'before-change-functions #'syntax-ppss-flush-cache t))
(setcar cell last)
- (setcdr cell cache)))
- ))
+ (setcdr cell cache)))))
+
+(define-obsolete-function-alias 'syntax-ppss-after-change-function
+ #'syntax-ppss-flush-cache "27.1")
+(defun syntax-ppss-flush-cache (beg &rest ignored)
+ "Flush the cache of `syntax-ppss' starting at position BEG."
+ ;; Set syntax-propertize to refontify anything past beg.
+ (setq syntax-propertize--done (min beg syntax-propertize--done))
+ ;; Flush invalid cache entries.
+ (setq syntax-ppss--done (min beg syntax-ppss--done)))
;;; FIXME: Explain this variable. Currently only its last (5th) slot is used.
;;; Perhaps the other slots should be removed?
@@ -477,8 +482,10 @@ syntax-ppss
running the hook."
;; Default values.
(unless pos (setq pos (point)))
+ (syntax-ppss--trim-cache syntax-ppss--done)
(syntax-propertize pos)
;;
+ (setq syntax-ppss--done (max syntax-ppss--done pos))
(with-syntax-table (or syntax-ppss-table (syntax-table))
(let* ((cell (syntax-ppss--data))
(ppss-last (car cell))
diff --git a/src/textprop.c b/src/textprop.c
index ae42c44185..be9e34c889 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -334,6 +334,9 @@ set_properties (Lisp_Object properties, INTERVAL interval, Lisp_Object object)
record_property_change (interval->position, LENGTH (interval),
XCAR (sym), XCAR (value),
object);
+ if (EQ (sym, Qsyntax_table)
+ && (interval->position < syntax_ppss__done))
+ syntax_ppss__done = interval->position;
}
/* For each new property that has no value at all in the old plist,
@@ -346,6 +349,9 @@ set_properties (Lisp_Object properties, INTERVAL interval, Lisp_Object object)
record_property_change (interval->position, LENGTH (interval),
XCAR (sym), Qnil,
object);
+ if (EQ (sym, Qsyntax_table)
+ && (interval->position < syntax_ppss__done))
+ syntax_ppss__done = interval->position;
}
}
@@ -400,6 +406,9 @@ add_properties (Lisp_Object plist, INTERVAL i, Lisp_Object object,
{
record_property_change (i->position, LENGTH (i),
sym1, Fcar (this_cdr), object);
+ if (EQ (sym1, Qsyntax_table)
+ && (i->position < syntax_ppss__done))
+ syntax_ppss__done = i->position;
}
/* I's property has a different value -- change it */
@@ -436,6 +445,9 @@ add_properties (Lisp_Object plist, INTERVAL i, Lisp_Object object,
{
record_property_change (i->position, LENGTH (i),
sym1, Qnil, object);
+ if (EQ (sym1, Qsyntax_table)
+ && (i->position < syntax_ppss__done))
+ syntax_ppss__done = i->position;
}
set_interval_plist (i, Fcons (sym1, Fcons (val1, i->plist)));
changed = true;
@@ -470,9 +482,14 @@ remove_properties (Lisp_Object plist, Lisp_Object list, INTERVAL i, Lisp_Object
while (CONSP (current_plist) && EQ (sym, XCAR (current_plist)))
{
if (BUFFERP (object))
- record_property_change (i->position, LENGTH (i),
- sym, XCAR (XCDR (current_plist)),
- object);
+ {
+ record_property_change (i->position, LENGTH (i),
+ sym, XCAR (XCDR (current_plist)),
+ object);
+ if (EQ (sym, Qsyntax_table)
+ && (i->position < syntax_ppss__done))
+ syntax_ppss__done = i->position;
+ }
current_plist = XCDR (XCDR (current_plist));
changed = true;
@@ -486,8 +503,13 @@ remove_properties (Lisp_Object plist, Lisp_Object list, INTERVAL i, Lisp_Object
if (CONSP (this) && EQ (sym, XCAR (this)))
{
if (BUFFERP (object))
- record_property_change (i->position, LENGTH (i),
- sym, XCAR (XCDR (this)), object);
+ {
+ record_property_change (i->position, LENGTH (i),
+ sym, XCAR (XCDR (this)), object);
+ if (EQ (sym, Qsyntax_table)
+ && (i->position < syntax_ppss__done))
+ syntax_ppss__done = i->position;
+ }
Fsetcdr (XCDR (tail2), XCDR (XCDR (this)));
changed = true;
@@ -2319,6 +2341,11 @@ inherits it if NONSTICKINESS is nil. The `front-sticky' and
Vtext_property_default_nonsticky
= list2 (Fcons (Qsyntax_table, Qt), Fcons (Qdisplay, Qt));
+ DEFVAR_INT ("syntax-ppss--done", syntax_ppss__done,
+ doc: /* Position up to which the `syntax-ppss' cache is valid. */);
+ syntax_ppss__done = -1;
+ Fmake_variable_buffer_local (intern ("syntax_ppss__done"));
+
interval_insert_behind_hooks = Qnil;
interval_insert_in_front_hooks = Qnil;
staticpro (&interval_insert_behind_hooks);
--
Alan Mackenzie (Nuremberg, Germany).
GNU bug tracking system
Copyright (C) 1999 Darren O. Benham,
1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.