On Fri, Sep 18, 2020 at 2:14 PM Lars Ingebrigtsen <larsi@gnus.org> wrote:

Mattias Engdegård <mattiase@acm.org> writes:

> When moving by sexp (C-M-f, C-M-u and so on) and point is already at a
> boundary preventing further movement, Emacs currently signals an
> internal error such as
>
> Scan error: "Containing expression ends prematurely", 5010, 5010
>
> or
>
> Scan error: "Unbalanced parentheses", 5010, 1
>
> which is unhelpful and rather looks as if something went wrong in the
> internal machinery.

Yes, those error messages are confusing in interactive usage.

I disagree strongly. Maybe the integers following them and

containing character positions are confusing, but the messages

themselves are fine.

Here's my use case. When selecting a certain amount of forms

inside another one, but not an outermost one, I type a lot of M-PC

until I see the "Containing expression..." message. I actively look

out for it. When it pops up, the region persists. I can then C-w

or do whatever, keeping that part of the code balanced. If, however,

the message is "Unbalanced parenthesis", I know something's up

and have to fix it.

Please don't remove the message and/or conflate the two cases.

João