Re^2: Empty qr// fails to match -- Is this known bug? (bug)

No, I still say it is a bug. Especially since print qr// prints a non-empty string, (?-xism:), and /(?-xism:)/ is not interpretted as an empty regex. More to the point, this rather clearly violates the principle of "least surprise". It isn't even useful. I'd actually prefer that even /$empty_string/ not trigger the "empty regex" special behavior. But it seems very clear to me that /$empty_regex/ should not trigger this behavior.

- tye

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Re^3: Empty qr// fails to match -- Is this known bug? (bug) by chibiryuu (Beadle) on Oct 23, 2008 at 15:04 UTC
Right, the problem to me is that `$U = qr/$some_user_provided_input/`, and this is very unexpected behavior. I agree with tye and not almut: since `"$U" ne ""`, `/$U/` shouldn't be an empty pattern, so `perlop`'s condition for empty `//` matching shouldn't apply. But after a bit of investigation, it seems that Perl always takes a shortcut: when `$rx = qr/foo/`, `/$rx/` turns into `/foo/`. Which explains this behavior, but I still think it's a bug.	[reply] [d/l] [select]
Re^3: Empty qr// fails to match -- Is this known bug? (bug) by chromatic (Archbishop) on Oct 23, 2008 at 17:39 UTC
The bug's in the stringification of `qr//`, if anywhere. The empty regex problem is (merely) an infelicity.	[reply] [d/l]
Re^3: Empty qr// fails to match -- Is this known bug? (bug) by rir (Vicar) on Oct 23, 2008 at 16:23 UTC
I don't see why the stringified representation of a Regex would be given any importance here. To me, the whole point of compiled Regexes is that they are not string Scalars. Globals suck. Be well, rir	[reply]
Re^4: Empty qr// fails to match -- Is this known bug? (bug) by chibiryuu (Beadle) on Oct 23, 2008 at 17:11 UTC
It's still inconsistent. `/$T$U/`, which is also empty (if you ignore the stringified representation), doesn't act like an empty `//`.	[reply] [d/l] [select]
Re^5: Empty qr// fails to match -- Is this known bug? (bug) by rir (Vicar) on Oct 23, 2008 at 20:35 UTC
Oh my, oh `my $var if 0;` another odd bug with desirable behaviour. Be well, rir	[reply] [d/l]