Re: ^ and comint-prompt-regexp

[Andy Moreton <andrewjmoreton@gmail.com>]

On Tue 12 Mar 2019, Stefan Monnier wrote:

>>     * lisp/comint.el (comint-output-filter): Revert last tweak because
>>     it can hang gdb indefinitely.
>
> Hmm... it would be worthwhile to investigate what's really going on here.
>
>> -            (while (string-match (concat "\\(" comint-prompt-regexp
>> +            (while (string-match (concat "\\(^" comint-prompt-regexp
>
> As the original author of this code, I must admit that I don't fully
> understand why this loop is here (it seems redundant with the
> immediately preceding loop, which was introduced by the same commit).

It looks to me that the first loop only removes prompts that match the
previous prompt found in the buffer text. The second loop removes any
prompts that match the regexp (which may not be the same as the previous
prompt if `comint-prompt-regexp' contains alternatives).

I presume it was done this way to be slightly faster ?

    AndyM