GNU bug report logs - #29159
27.0.50; Hang in HTML/CSS code

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 27.0.50; Hang in HTML/CSS code
Date: Sun, 05 Nov 2017 18:39:29 +0100

If I put the following into a file called foo.html:

<style>
@keyframes dropFlowParticles {
  0% { background-position: 0 0, 0 0, 30px 40px, 0 0, 10px 0; }
}
</style>

End then delete the 0%, and then start typing "top", then Emacs will
hang kinda hard.  A C-g will eventually break out and the "t" will be
inserted, but then Emacs hangs again.

Setting debug-on-quit doesn't give me a backtrace, so I'm not sure where
it's hanging.


In GNU Emacs 27.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2017-11-03 built on mouse
Repository revision: 620247ac205b80ceb142ee70500ab2c3ffa46fe2
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
System Description:	Ubuntu 17.04


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #8 received at 29159 <at> debbugs.gnu.org (full text, mbox):

From: Olaf Rogalsky <olaf.rogalsky <at> t-online.de>
To: 29159 <at> debbugs.gnu.org
Subject: 26.0.90; Input decoding is sometimes skipped in TTY (xterm-mouse-mode)
Date: Sun, 05 Nov 2017 20:53:08 +0100

Hi,

in case of a button down event, `describe-key' has some trickery to also
read the forthcoming up event. The following patch makes this trickery
work with xterm-mouse-mode.

I don't have write permission to the repositiory. I therefore would
appreciate it very much, if someone else could review und submit the
patch.

PS: It would be nice, if that person also can have a look at patch #29104

PSS: I don't think, that #29143 is related. Both, `Evil-mode' *and*
     `xterm-mouse-mode' fool around with the ?\e prefix in the
     `input-decode-map', but they obviously do it in an incompatible
     way.

diff --git a/lisp/help.el b/lisp/help.el
index bc8035db0e..247f060f24 100644
--- a/lisp/help.el
+++ b/lisp/help.el
@@ -753,7 +753,7 @@ help-read-key-sequence
                     (and (> (length key) 1)
                          (eventp (aref key 1))
                          (memq 'down (event-modifiers (aref key 1)))))
-                (read-event))))
+                (aref (read-key-sequence-vector nil) 0))))
       ;; Put yank-menu back as it was, if we changed it.
       (when saved-yank-menu
         (setq yank-menu (copy-sequence saved-yank-menu))


-- 
Olaf Rogalsky
Schwörhausgasse 5
89073 Ulm
Germany

Message #11 received at 29159 <at> debbugs.gnu.org (full text, mbox):

From: Simen Heggestøyl <simenheg <at> gmail.com>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: Tom Tromey <tom <at> tromey.com>, 29159 <at> debbugs.gnu.org
Subject: Re: bug#29159: 27.0.50; Hang in HTML/CSS code
Date: Sun, 05 Nov 2017 22:55:59 +0100

[Message part 1 (text/plain, inline)]

The bug is also present in Emacs 26.

It looks like `mhtml--extend-font-lock-region' and
`font-lock-extend-region-multiline' are squabbling about where to
leave `font-lock-beg'.

In this particular example, `mhtml--extend-font-lock-region' wants to
leave `font-lock-beg' at 40 while `font-lock-extend-region-multiline'
wants it at 39, resulting in an endless back and forth.

CC-ing Tom in case he has some insight into how it should be fixed.

-- Simen

[Message part 2 (text/html, inline)]

Message #14 received at 29159 <at> debbugs.gnu.org (full text, mbox):

From: Tom Tromey <tom <at> tromey.com>
To: Simen Heggestøyl <simenheg <at> gmail.com>
Cc: Lars Ingebrigtsen <larsi <at> gnus.org>, Tom Tromey <tom <at> tromey.com>,
 29159 <at> debbugs.gnu.org
Subject: Re: bug#29159: 27.0.50; Hang in HTML/CSS code
Date: Sun, 12 Nov 2017 11:50:05 -0700

>>>>> "Simen" == Simen Heggestøyl <simenheg <at> gmail.com> writes:

Simen> CC-ing Tom in case he has some insight into how it should be fixed.

Stefan found another bug in mhtml--extend-font-lock-region, so I sort of
suspect it needs a rethink.

However, in this case, I wonder why font-lock-extend-region-multiline is
even needed.  What about removing it?  I don't remember why I put it in
there in the first place.

This seems to fix the problem for me.  Though I wonder if it is actually
needed for something.

Tom

diff --git a/lisp/textmodes/mhtml-mode.el b/lisp/textmodes/mhtml-mode.el
index 5854167750..bdb95887c1 100644
--- a/lisp/textmodes/mhtml-mode.el
+++ b/lisp/textmodes/mhtml-mode.el
@@ -367,7 +367,8 @@ mhtml-mode
               #'mhtml--submode-fontify-region)
   (setq-local font-lock-extend-region-functions
               '(mhtml--extend-font-lock-region
-                font-lock-extend-region-multiline))
+                ;; font-lock-extend-region-multiline
+                ))
 
   ;; Attach this to both pre- and post- hooks just in case it ever
   ;; changes a key binding that might be accessed from the menu bar.

Message #19 received at 29159-done <at> debbugs.gnu.org (full text, mbox):

From: Tom Tromey <tom <at> tromey.com>
To: 29159-done <at> debbugs.gnu.org
Subject: done
Date: Sat, 25 Nov 2017 13:49:16 -0700

I've checked in a patch to fix this problem.

Tom

Message #22 received at 29159 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Simen Heggestøyl <simenheg <at> gmail.com>
Cc: Lars Ingebrigtsen <larsi <at> gnus.org>, Tom Tromey <tom <at> tromey.com>,
 29159 <at> debbugs.gnu.org
Subject: Re: bug#29159: 27.0.50; Hang in HTML/CSS code
Date: Sat, 25 Nov 2017 21:17:20 -0500

> In this particular example, `mhtml--extend-font-lock-region' wants to
> leave `font-lock-beg' at 40 while `font-lock-extend-region-multiline'
> wants it at 39, resulting in an endless back and forth.

Could you give some details?
Functions on font-lock-extend-region-functions should *never* shrink
a region (since that risks inf-looping, obviously).  After all, it's
called "...-extend-...", right?

So if font-lock-extend-region-multiline puts beg at 39, it's incorrect
for mhtml--extend-font-lock-region to move it back to 40.


        Stefan

Message #25 received at 29159 <at> debbugs.gnu.org (full text, mbox):

From: Simen Heggestøyl <simenheg <at> gmail.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: larsi <at> gnus.org, tom <at> tromey.com, 29159 <at> debbugs.gnu.org
Subject: Re: bug#29159: 27.0.50; Hang in HTML/CSS code
Date: Sun, 26 Nov 2017 15:52:38 +0100

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:
> Could you give some details?
> Functions on font-lock-extend-region-functions should *never* shrink
> a region (since that risks inf-looping, obviously).  After all, it's
> called "...-extend-...", right?
>
> So if font-lock-extend-region-multiline puts beg at 39, it's incorrect
> for mhtml--extend-font-lock-region to move it back to 40.

`font-lock-beg' got set back to 40 from 39 at line 184 from the call to
`previous-single-property-change'.

-- Simen

Message #28 received at 29159 <at> debbugs.gnu.org (full text, mbox):

From: Tom Tromey <tom <at> tromey.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: Lars Ingebrigtsen <larsi <at> gnus.org>, Tom Tromey <tom <at> tromey.com>,
 Simen Heggestøyl <simenheg <at> gmail.com>, 29159 <at> debbugs.gnu.org
Subject: Re: bug#29159: 27.0.50; Hang in HTML/CSS code
Date: Sun, 26 Nov 2017 10:36:02 -0700

>>>>> "Stefan" == Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

Stefan> So if font-lock-extend-region-multiline puts beg at 39, it's incorrect
Stefan> for mhtml--extend-font-lock-region to move it back to 40.

What I did is set it up to do the multiline extension at the end of
mhtml--extend-font-lock-region.  I think this should make it work correctly
now.

Tom

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