The interesting part to me is that it seems that Java would be perfectly capable of differentiating between methods by return type if the compiler was tweaked slightly. Is there a reason why this isn't a formal language feature?
Edit: here's the edge case though. You can call a function and use the return value directly as a parameter: foo(bar()). It's possible to have two foo that take both possible bar return types, at which point the compiler is stuck.
It could require a cast in this instance, however. The more I think about this the more I wonder why this isn't possible.
That's no more an edge case than the cases where you throw away the return value or you're binding to an ambiguous type e.g. `A getFoo()`, `B getFoo()`, `Object foo = getFoo()`.
> The more I think about this the more I wonder why this isn't possible.
The Java spec does not say, for C++ Stroustrup states it's
> to keep resolution for an individual operator or function call context-independent.
the Java reason is likely also some sort of Principle of Least Surprise claim.