bug#30393: 24.4; cperl-mode: indentation failure

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 10 Feb 2018 11:26:54 +0000
> From: Alan Mackenzie <acm@muc.de>
> Cc: Noam Postavsky <npostavs@users.sourceforge.net>,
> 	Stefan Monnier <monnier@IRO.UMontreal.CA>, 30393@debbugs.gnu.org
> 
> +definition, or defun.  Therefore, in these modes, don't put an opening

Which "these modes" does this refer to?  How will the reader know when
to use this convention and when not?

> +  In earlier versions of Emacs (through version 26.n), Emacs exploited
> +this convention to speed up many low-level operations, which would
> +otherwise have to scan back to the beginning of the buffer.
> +Unfortunately, this caused confusion when an opening delimiter
> +occurred at column zero inside a comment.  The resulting faulty
> +analysis often caused wrong indentation or fontification.  The
> +convention could be overridden by setting the user option
> +@code{open-paren-in-column-0-is-defun-start} to @code{nil}, but this
> +slowed Emacs down, particularaly when editing large buffers.
> +
> +  To eliminate these problems, the low level functionality which used
> +to test for opening delimiters at column 0 no longer does so.  Open
> +delimiters may now be freely written at the left margin inside
> +comments and strings without triggering these problems.

This text is not needed.  The original text, which you deleted,
described how to avoid a real problem; if that problem no longer
exists, we should just delete that text.  If that problem does exist
in some modes, we should leave that text as it was, with a better
description of what modes are still subject to these problems.

But describing something that is no longer done by Emacs is just waste
of paper.

Overall, I must say I'm confused regarding the purpose of this patch.
What does it try to accomplish?

Thanks.