bug#17757: 24.4.50; Whitespace changes break signature mark

[Lars Ingebrigtsen <larsi@gnus.org>]

Marcin Borkowski <mbork@mbork.pl> writes:

> I confirm that this is still a problem in GNU Emacs 25.1.50.2 (Git
> commit 4ccd2688).
>
> Steps to reproduce in emacs -Q:
>
> C-x m (compose-mail)
> M-> (end-of-buffer)
> "-- " (i.e., dash - dash - space)
> RET
>
> Now the space after the sigdashes disappears.

It's still present in Emacs 27.

> Running Edebug on `newline' reveals that this happens during evaluation
> of this form:
>
> (unwind-protect
>           (progn
>             (add-hook 'post-self-insert-hook postproc nil t)
>             (self-insert-command (prefix-numeric-value arg)))
>         ;; We first used let-binding to protect the hook, but that was naive
>         ;; since add-hook affects the symbol-default value of the variable,
>         ;; whereas the let-binding might only protect the buffer-local value.
>         (remove-hook 'post-self-insert-hook postproc t))

Hm...  that's odd.  If I set that hook to nil, then the space at the end
of the line still disappears, so I don't see how that could be the
problem.

Or do you mean that it happens in `self-insert-command' itself?

-- 
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   bloggy blog: http://lars.ingebrigtsen.no