in reply to Why does /i not seem to work

Try examining the $rx: 
(?^:abc|xyz)

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The sequence ?^ is described in perlre:

> Starting in Perl 5.14, a "^" (caret or circumflex accent) immediately after the "?" is a shorthand equivalent to "d-imnsx". Flags (except "d") may follow the caret to override it. But a minus sign is not legal with it.

-i means the qr() by default creates case sensitive regex objects.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

In Section Seekers of Perl Wisdom