I view 

/(?:(?!$re).)*/s

[download]

as the equivalent of 

/[^$chars]*/

[download]

except it can prevent the match of entire regexps instead of a choice of characters. I call it the common use of a negative lookahead. If you're using a negative lookahead, that construct will probably satisfy your needs.

Keep in mind that both expressions can successfully match 0 characters if not properly anchored.

I think it would be nice if /(?^$re)/ could be added as a shortcut to /(?:(?!$re)(?s:.)*/. It would be more readable, and it would help prevent the common misuse of negative lookahead (/(?!$re.*)/).

Update: Formatting.

In reply to Re: Look-Arounds in Regexes are Hard (Common Use of a Negative Lookahead) by ikegami
in thread Look-Arounds in Regexes are Hard by moritz

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