chromatic wrote What's Wrong with Perl 5:

When is a block a block, and when is it a hash reference?

Seems like your problem illustrates this point.

$ perl
use strict;
use warnings;
my $xnix='X';

sub f {
  my $z = {$xnix => 100}->{'X'}; # make it a hash reference
  return $z;
}

print f(),"\n";
__END__
100
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