Rewriting lambdas to method references can produce ambiguous code that doesn't compile

[jackwickham]

What happened?

If a method has two overloads, one for Function and one for BiFunction, it's possible for the rule to rewrite lambdas to produce ambiguous code. x -> y.get(x) is unambiguous, but y::get may be ambiguous if there are multiple variants of get.

What did you want to happen?

It shouldn't rewrite those lambdas, or rewriting them should include the cast required to make it unambiguous.

[ferozco]

The issue is actually with the receiver of the lambda being overloaded, not with the lambda itself. We could verify that there isn't an overload to avoid the problem. In practice I've only seen this with KeyedStream which in generally deprecated in favour of EntryStream