Hello, fellow monks! I'm seeing strange things going on with my hash keys. 
#! /usr/bin/perl
use strict;
use warnings;
use utf8;

sub U { return utf8::is_utf8($_[0])?'is_utf8':'not_utf8'; }  

my %s = (
     MaxAccountSize1   => 1,
     'MaxAccountSize2' => 1,
     2 => 1,
);

foreach (sort keys %s) {
     print "'$_' ".U($_)." => '".$s{$_}."' ".U($s{$_})."\n";
}

[download]
It looks like in presence of use utf8 hash keys upgraded from barewords via virtues of => operator get the utf8 flag. Quoted string literals on the contrary get this flag on if they contain characters with high codes -- in full accordance with the docs. It cost us a lot of blood and sweat to debug why some perfectly ASCII strings would suddenly get the flag.

Is there any rationale in such decision? Is it a bug? Does anyone know what the performance penalty of utf8 hash keys -- even if they contain only ASCII chars -- is?

--kap

In reply to Unexpected utf8 in hash keys by kappa

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