Pragmas (including the feature pragma) don't propagate into (?{}) and (??{}). It's a known bug.

Example of strict and warnings not propagating: 

use strict;
use warnings;
use re 'eval';
my $re = '';
'' =~ /$re(?{ print(">$x<\n"); })/;

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><

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Update: Added link and example

In reply to Re: Can't say in a regex? by ikegami
in thread Can't say in a regex? by JadeNB

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