Funny, I ran into the exact same problem like ten minutes ago and decided to feed the error message to the Monastery which turned up this thread :) I was trying to make some older code visually simpler now that it requires 5.10.1+ anyway.

Yeah, that listref is not the most intuitive construction although visually the square brackets work OK for me; round ones would look redundant. What I used before was List::MoreUtils, which while non-core is fairly ubiquitous and has "any" that does shortcut. Though with lists of a size that you want to specify as literals in the source it probably makes zero difference.