In the third case, you are assigning
@jazz = ( @{ $_[0] } || () );

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The || operator forces scalar context on the left operand, so it returns the number of elements in the referenced array. If the array is empty, the number is 0, so || works and returns undef, i.e. empty array.

In reply to Re: Dereference Empty(!) Array by choroba
in thread Dereference Empty(!) Array by lukestyle

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