Method overloading fails to resolve to correct method

[AlexMSmithCA]

I have an overloaded method that has two distinct signatures. One signature is a generic that returns the invoked argument (e.g. returns some element in an encapsulation container). If I construct a type that is a union of this generic type (e.g. Encapsulator<number> | Encapsulator<string>), I see some odd behavior. If I removed the un-used overloaded method signature, there are no errors.

---

Simplified example on flow.org/try. Remove line 12 and type checking succeeds.

type Encapsulator<T> = {
  (): T
};
function encapsulate<TToEncapsulate>(obj: TToEncapsulate): Encapsulator<TToEncapsulate> {
  return () => obj;
}

type ExtractReturnType = <V>(() => V) => V;

declare class Deencapsulator {
  provide<T: Encapsulator<*>>(encapsulated: T): $Call<ExtractReturnType, T>,
  provide(num: number): number
}

const instance = new Deencapsulator();

type EncapsulatedOrNumber = Encapsulator<string> | Encapsulator<number>;
const whoKnows: EncapsulatedOrNumber = ({}: any);
const stringOrNumber = instance.provide(whoKnows);

Yields the following error:

19: const stringOrNumber = instance.provide(whoKnows);
                                            ^ Cannot call `instance.provide` because number [1] is incompatible with string [2] in type argument `T` [3] of type argument `T`.
References:
17: type EncapsulatedOrNumber = Encapsulator<string> | Encapsulator<number>;
                                                                    ^ [1]
17: type EncapsulatedOrNumber = Encapsulator<string> | Encapsulator<number>;
                                             ^ [2]
1: type Encapsulator<T> = {
                     ^ [3]

Commenting out provide(num: number): number yields no errors.

[gajus]

Related:

• Method overloading fails to resolve to correct method #6265
• Support refining overloaded functions without callback annotation #5593
• Flow choosing incorrect overload. #2891
• Flow does not accept intersection function types even with disjoint unions #3021 (comment)