[hnu0847]

Why does the following expect arguments:

    : sub {};

Don't all perl subroutines allow any number of arguments (including 0) to be passed?

Does the fact that the above is an anonymous subroutine affect the answer to my question?

[jwilk]

A sub without prototype (anonymous or not) indeed allows any number of arguments. That's sufficient to trigger the syntax error.

[hnu0847]

So basically this:

    sub() {}

does not try to parse the /1;#/+ as an argument because the () indicates there are no arguments (although they could be explicitly included if f were called with (), whereas this:

    sub f {}

does try to parse the /1;#/+ as an argument because that's perl's behavior if () are omitted?

[jwilk]

That's right.