@foo interpolated (which happens in the glob operator)

But glob() can't take an array, AFAIK. It just takes a single expression. For instance glob(@foo) turns the @foo into "8", just as doing glob(scalar(@foo)).

So is the above a known extension to glob() when using <> (everything I'd seen just talked about <> being a shortcut, not having extra features).

Even 5.8.0's File::Glob doesn't mention anything about being able to do shell argument expansion. And passing the list to bsd_glob() just takes the first argument. It's almost like it is doing a (join " ", @foo) somewhere.