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

[João Távora]

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.

Closing this bug.  Let me know if I should reopen.
João