Bug#780805: Freezes using 100% CPU when editing OCaml file

[Stéphane Glondu <glondu@debian.org>]

Le 19/03/2015 20:34, Ralf Treinen a écrit :
>> Edit a .ml file with the following line:
>>
>>   fun () -> assert false
>>
>> Then, go to the first column and start deleting characters (using
>> DEL). When ) is reached, emacs freezes. It uses 100% CPU and makes no
>> system calls. This doesn't happen outside of tuareg-mode.
> 
> I cannot reproduce this. For me, everything is fine. When I reach the point
> where ')' is the first symbol on the line, nothing freezes, and CPU usage
> continues to be normal.

The problem happens after deleting ) (when ' ' is the first symbol on
the line).

>> Versions of packages tuareg-mode depends on:
>> ii  emacs              46.1
>> ii  emacs24 [emacsen]  24.4+1-5
>> ii  emacsen-common     2.0.8
> 
> I have precisely the same.
> 
> maybe it is an interaction with some other emacs macros ? Can you try again
> without loading into emacs anything else besides tuareg ?

It appears to be an interaction with show-paren-mode. In a clean sid chroot:

 1. apt-get install emacs-nox
 2. apt-get install tuareg-mode
 3. emacs /tmp/toto.ml
 4. Insert "fun () -> assert false"
 5. M-x show-paren-mode
 6. Go to first character and start deleting characters


Cheers,

-- 
Stéphane