Question

Given this generic function:

<T> List<T> function() { return null; }

Why does this compile

List<String> l = function();

While this does not?

List<String> l = (List<String>) function();

Answer 1

It looks like type inference happens after the cast is attempted (by the compiler).

The type of the expression is determined by the left side of the expression, which is not yet “parsed” when the cast is attempted. And the cast itself fails because, with not-yet-inferred type, the result (of the method invocation) is of type List<Object>

Section 15.12.2.7 of the JLS indicates that type inference happens last.