That's a surprising loophole, since perl is aware of the danger of runtime evaluation of a regexp with an eval group: 

% perl -e '/$ARGV[0]/' '(?{print "nasty\n"})'
Eval-group not allowed at runtime, use re 'eval' in regex m/(?{print "
+nasty\n"})/ at -e line 1.
% perl -e 'eval qq(/$ARGV[0]/)' '(?{print "nasty\n"})'
nasty

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the lowliest monk

In reply to Re^3: qr/string/ is not the same as qr/$var/ ? by tlm
in thread qr/string/ is not the same as qr/$var/ ? by grinder

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