Subject: bug#47657: python-shell font-lock with multi-line input: runaway fontification buffer length

From: Lars Ingebrigtsen <[email-masked]>
Date: Tue, 13 Apr 2021 10:05:40 +0200

JD Smith <[email-masked]> writes:

>  Do you have a step-by-step recipe, starting from "emacs -Q", to
>  reproduce this problem?
>
> 1 emacs -Q
> 2 M-x run-python
> 3 C-x 5 b “ *Python-font-lock*”
> 4 In inferior python shell: type any line.
> 5 C-c SPC (`comint-accumulate’) to continue.
> 6 Type another line.  Notice the first line is repeated. 
> 7 Repeat steps 5 & 6 several times. 

You didn't say what Emacs version you're using -- I tested this in Emacs
28, and was unable to reproduce this.  The " *Python-font-lock*" buffer
never contains more than a single non-blank line using this recipe.
(The "any line" I used to test was "5".)

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