bug#51089: 28.0.60; Using read-symbol-shorthands (("-" . "foo-")) shouldn't shadow the '-' symbol

[Eli Zaretskii]

> From: João Távora <joaotavora@gmail.com>
> Cc: 51089-done@debbugs.gnu.org,  Richard Stallman <rms@gnu.org>
> Date: Mon, 11 Oct 2021 22:36:14 +0100
> 
> João Távora <joaotavora@gmail.com> writes:
> >>  Yes.  But I think we could use strcspn for an easier, one-line, test
> >>  of the same.
> > Seems I didn't try very hard :-)  Using strspn() instead of strcpsn() does
> > work.  Patch below, with a constant string of ASCII punctuation that
> > you'll probably want to tweak.
> 
> Hello Eli,
> 
> I took the initiative and pushed the patch to emacs-28 after settling on
> the string:
> 
>    "^*+-/<=>_|"
> 
> I chose this string after analysing the Emacs Lisp symbols that are only
> punctuation.  I used this Elisp form (very inneficient, but did the job).
> 
>    (let ((all-punctuation))
>      (mapatoms (lambda (symbol)
>                  (when (with-temp-buffer
>                          (insert (symbol-name symbol))
>                          (goto-char (point-min))
>                          (skip-syntax-forward "_")
>                          (eobp))
>                    (push symbol all-punctuation))))
>      all-punctuation)
> 
> This returns the following symbols, which I think is the full set of
> "protected" ones:
> 
>    ;; => (& * + - / < = > _ | ** ++ -- -/ -> /= <= <> >= || ¬ --- --> ->>)
> 
> One of them isn't ASCII, but as we discussed it's likely not used a
> shorthand prefix.

Thanks, looks okay to me (modulo some minor changes in wording of
comments and documentation).