bug#37659: rx additions: anychar, unmatchable, unordered-or

[Phil Sainty]

On 24/10/19 2:56 PM, Drew Adams wrote:
> Is there an identifiable subset of rx features ... that map
> (even if not one-to-one) to regexp syntax components?

C-h f rx

(syntax SYNTAX)  Match a character with syntax SYNTAX, being one of:
  whitespace, punctuation, word, symbol, open-parenthesis,
  close-parenthesis, expression-prefix, string-quote,
  paired-delimiter, escape, character-quote, comment-start,
  comment-end, string-delimiter, comment-delimiter