Why does this code generate an error (Can't use an undefined value as a HASH reference) instead of autovivifying $h{x}? 
#!/usr/bin/perl -w
use strict;
my %h;
%{$h{x}};

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If I use keys(), then it does autovivify $h{x}. 
#!/usr/bin/perl -w
use strict;
my %h;
keys %{$h{x}};

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In reply to Keys() required to autovivify? by jrw

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