[REGEX] @ symbol'd array interpolation doesn't backtrack (from rt #127906)

[raiph]

Shifting bug here with new info from 2016 rt issue: https://rt.perl.org/Public/Bug/Display.html?id=127906

I haven't closed the rt bug yet. I can no longer login to rt. Can I close a bug via email? If so, how? TIA.

v2018.12

my @array = < a ab >;
say 'abc' ~~ /  |< a ab >    b /;  # ab
say 'abc' ~~ /  |@array      b /;  # Nil (expected ab)
say 'abc' ~~ /  |@(< a ab >) b /;  # Nil (expected ab)
say 'abc' ~~ / ||< a ab >    c /;  # abc
say 'abc' ~~ / ||@array      c /;  # Nil (expected abc)
say 'abc' ~~ / ||@(< a ab >) c /;  # Nil (expected abc)

[raiph]

After golfing https://rt.perl.org/Public/Bug/Display.html?id=126713 I believe it boils down to a duplicate of this bug:

my @a = < a b bc cd >;
say "abcd" ~~ /^( < a b bc cd > )*?$/; # ｢abcd｣ etc.
say "abcd" ~~ /^( @a            )*?$/; # Nil

Thus it should be annotated and closed as such.