I don't understand what do you thing with this code???

Plus :: and ' (treated as ::):

$ perl -wle"print STDOUT I'm::a::bareword"
I::m::a::bareword
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The rules say a bareword is something that looks like an identifier but is treated like a string. Abigail-II was saying an identifier is (typically) made of letters, digits, and underscores; I was pointing out that it can also include the package separator :: and its deprecated older version ', and also pointing out that ' is translated into the newer :: even though the identifier will end up being considered a string.

But you should be using strict and warnings which makes the above irrelevant.