From the doc for keys:

Starting with Perl 5.14, an experimental feature allowed keys to take a scalar expression. This experiment has been deemed unsuccessful, and was removed as of Perl 5.24.

So when you "tested" this the very best possible result was that you saw the "keys on reference is experimental" warning and blithely ignored it. Otherwise your code didn't compile at all and you ignored that.

In reply to Re^2: merge two hashes into one by hippo
in thread merge two hashes into one by ovedpo15

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