If you compare the output of your empty_list routine in scalar and list context: 
sub empty_list {
  return @{ [] }
}

my @y=(empty_list())[0];
my $x = (empty_list())[0];
use Data::Dumper;print Dumper \$x,\@y;

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You will see that @y is an empty array, and $x is undef.

think of the difference between using $x and @y in your hash declaration: 

my @y=(empty_list())[0];  # @y = ();
my $x = (empty_list())[0];  # $x = undef;

my %x = (foo=>$x);
my %xx = (foo=>@y);

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So, to use your function in your hash declaration, you need to force scalar context. 
my %x=(foo=>scalar((empty_list1())[0]));

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In reply to Re: Empty List miracle (2) by Sandy
in thread Empty List miracle (2) by rovf

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