RE: [External] : Re: Use the characters "+" and "-" in regular expressions

[Drew Adams]

> Hm. According to the docs, the dash should go last, but 
> a test actually confirms that it works in first position.

I quoted this from (elisp) `Regexp Special':

   To include a ‘-’, write ‘-’ as the first or last
                                      ^^^^^^^^^^^^^
   character of the character alternative, or as the
   upper bound of a range.  Thus, ‘[]-]’ matches both
   ‘]’ and ‘-’.

That's from Emacs 26 (and all prior releases, at least
as far back as Emacs 20).  But yes, they changed that
text for Emacs 27, to this:

   To include ‘-’, put it at the end.
                          ^^^^^^^^^^
___

For Emacs 20, it says this:

   To include a `-', write `-' as the first or last
   character of the character alternative, or put it
   after a range.  Thus, `[]-]' matches both `]' and
   `-'.