What does static_cast mean when it's followed by two pairs of parentheses?

Question

What does this say:

return static_cast<Hasher &>(*this)(key);

?

I can't tell whether *this or key is passed to static_cast. I looked around and found this answer, but unlike what I'm stuck on, there's nothing inside the first pair of parentheses.

Answer 1

The statement is parsed as

return (static_cast<Hasher &>(*this))(key);

So, the argument to static_cast is *this. Then the result of the cast, let's call it x, is used as postfix-expression in a function call with key as argument, i.e. x(key), the result of which is returned.