This test demonstrates code that has worked for me until 5.17.0. It fails in 5.17.0 and higher. 

#!/usr/bin/env perl
use strict;
use warnings;
use Test::More tests => 2;

my $str     = ' Foo ';    # uppercase breaks 2nd regex
my $pattern = 'foo';
utf8::upgrade($str);
utf8::upgrade($pattern);

my $re          = qr/$pattern/i;
my $re_optional = qr/(?i:.?)$pattern/i;

like( $str, $re,          "re" );
like( $str, $re_optional, "re_optional" );

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Am I missing something?

In reply to case-insensitive regexp bug in perl 5.17.x? by karpet

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