--- Begin Message ---
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Subject: |
Emacs 29.0.60: font-lock throws an args-out-of-range error with a long line. |
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Date: |
Sun, 5 Feb 2023 14:54:35 +0000 |
Hello, Emacs.
This bug is reproducible in both the master branch and release branch as
updated yesterday evening (European time).
To reproduce this bug:
(i) Apply this bug fix to CC Mode, and byte compile the defun (or file),
and make sure it's loaded:
diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 2631c24f8db..9fa727d9e1f 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -5915,19 +5915,21 @@ c-determine-limit
(cond
((> pos start) ; Nothing but literals
base)
- ((> base (point-min))
+ ((and
+ (> base (point-min))
+ (> (- base try-size) (point-min))) ; prevent infinite recursion.
(c-determine-limit how-far-back base (* 2 try-size) org-start))
(t base)))
((>= count how-far-back)
(c-determine-limit-no-macro
- (+ (car elt) (- count how-far-back))
- org-start))
+ (+ (car elt) (- count how-far-back))
+ org-start))
((eq base (point-min))
(point-min))
((> base (- start try-size)) ; Can only happen if we hit point-min.
(c-determine-limit-no-macro
- (car elt)
- org-start))
+ (car elt)
+ org-start))
(t
(c-determine-limit (- how-far-back count) base (* 2 try-size)
org-start))))))
(ii) M-: (setq backtrace-on-redisplay-error t)
(iii) C-x b temp.cc. M-x c++-mode.
(iv) Type in the following text:
char foo [] = R"foo(
)foo"
(v) With point at the end of the first line in temp.cc,
M-: (insert (make-string 260000 ?y))
This may take some time to execute.
(vi) C-x 4 b *Redisplay_trace*
The following backtrace will be seen:
Error: args-out-of-range (260028 260028)
mapbacktrace(#f(compiled-function (evald func args flags) #<bytecode
0xdf8c26265ae87c7>))
debug-early-backtrace()
debug-early(error (args-out-of-range 260028 260028)) <===============
get-text-property(260028 font-lock-multiline)
font-lock-extend-region-multiline()
font-lock-default-fontify-region(1 260029 nil)
c-font-lock-fontify-region(1 1501 nil)
font-lock-fontify-region(1 1501)
#f(compiled-function (fun) #<bytecode
-0x156eee0f20909c83>)(font-lock-fontify-region)
run-hook-wrapped(#f(compiled-function (fun) #<bytecode -0x156eee0f20909c83>)
font-lock-fontify-region)
jit-lock--run-functions(1 1501)
jit-lock-fontify-now(1 1501)
jit-lock-function(1)
redisplay_internal\ \(C\ function\)()
This is clearly a bug.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
Position 260028 is within the bounds of the buffer. It would appear
that the new-ish long-lines code has narrowed the buffer at some stage
such that point-max is less than the end of the buffer. I propose the
following simple patch which fixes (or works around) this bug:
diff --git a/lisp/font-lock.el b/lisp/font-lock.el
index 1fa45379b9f..9e944fe188a 100644
--- a/lisp/font-lock.el
+++ b/lisp/font-lock.el
@@ -1154,6 +1154,8 @@ font-lock-default-fontify-region
"Fontify the text between BEG and END.
If LOUDLY is non-nil, print status messages while fontifying.
This function is the default `font-lock-fontify-region-function'."
+ (or (<= end (point-max))
+ (setq end (point-max)))
(with-silent-modifications
;; Use the fontification syntax table, if any.
(with-syntax-table (or font-lock-syntax-table (syntax-table))
--
Alan Mackenzie (Nuremberg, Germany).
--- End Message ---
--- Begin Message ---
|
Subject: |
Re: bug#61298: Emacs 29.0.60: font-lock throws an args-out-of-range error with a long line. |
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Date: |
Sun, 5 Feb 2023 16:04:05 +0000 |
Hello, Eli.
On Sun, Feb 05, 2023 at 17:12:42 +0200, Eli Zaretskii wrote:
> > Date: Sun, 5 Feb 2023 14:54:35 +0000
> > From: Alan Mackenzie <acm@muc.de>
> > Error: args-out-of-range (260028 260028)
> > mapbacktrace(#f(compiled-function (evald func args flags) #<bytecode
> > 0xdf8c26265ae87c7>))
> > debug-early-backtrace()
> > debug-early(error (args-out-of-range 260028 260028)) <===============
> > get-text-property(260028 font-lock-multiline)
> > font-lock-extend-region-multiline()
> > font-lock-default-fontify-region(1 260029 nil)
> > c-font-lock-fontify-region(1 1501 nil)
> > font-lock-fontify-region(1 1501)
> > #f(compiled-function (fun) #<bytecode
> > -0x156eee0f20909c83>)(font-lock-fontify-region)
> > run-hook-wrapped(#f(compiled-function (fun) #<bytecode
> > -0x156eee0f20909c83>) font-lock-fontify-region)
> > jit-lock--run-functions(1 1501)
> > jit-lock-fontify-now(1 1501)
> > jit-lock-function(1)
> > redisplay_internal\ \(C\ function\)()
> > This is clearly a bug.
> > ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> > Position 260028 is within the bounds of the buffer. It would appear
> > that the new-ish long-lines code has narrowed the buffer at some stage
> > such that point-max is less than the end of the buffer. I propose the
> > following simple patch which fixes (or works around) this bug:
> Fine with me, please install on the emacs-29 branch, and thanks.
I have done so, and I'm closing the bug with this post.
Thanks for such a rapid response.
--
Alan Mackenzie (Nuremberg, Germany).
--- End Message ---