Of course, you could change it to "when there's no calling context", but then half a year down the road, someone will find that sentence confusing, and change to "top level of a file".

Which will make it confusing for others. A no-op seems wrong to me in this case; maybe the better thing is to make an effort to definitely clarify this matter.

What we really lack here is maybe a formal definition of context, and in particular of when you have a context and when you don't have it. I know that perldata has an entire section about context, but the definition results quite foggy IMHO, and resorts to wantarray to disambiguate. The classic dog-biting-its-own-tail problem. Moreover, I'm not in the position to propose an alternative, and this is quite frustrating.