^ and comint-prompt-regexp (was: [Emacs-diffs] master d58c29b: Revert last tweak in 'comint-output-filter')

[Stefan Monnier]

>     * 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

Since comint-prompt-regexp almost always starts with "^", this change
seems to be fundamentally wrong: it will give a regexp of the form
\(^^...\) which interprets the second ^ as an actual ^ char rather than
as a `bolp` check.

So if it avoids a problem, it's likely not the right fix but rather
because it just deactivates this loop.

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).

Maybe we should just comment it out.


        Stefan