TypeScript unable to infer types properly between interfaces and overloaded methods.

Bug Report

In all versions of TS I can find, there's no way to mark certain call patterns of a method as deprecated while maintaining inference with certain interfaces. If an interface is split out into different overloads so certain overloads can be deprecated, then it breaks inference in some cases.

🔎 Search Terms

I'm not sure what to search for here. Interfaces?

🕗 Version & Regression Information

• All versions

⏯ Playground Link

Playground link with relevant code

💻 Code

interface Observer<T> {
    next(value: T): void;
    error(error: any): void;
    complete(): void;
}

interface Unsubscribable {
    unsubscribe(): void;
}

interface Subscribable<T> {
    subscribe(observer?: Partial<Observer<T>>): Unsubscribable;
}

class Observable<T> implements Subscribable<T> {
    /////////////////////////////////////////
    // Valid call pattern
    /////////////////////////////////////////
    subscribe(observerOrNext?: Partial<Observer<T>> | ((value: T) => void)): Unsubscribable;


    //////////////////////////////////////////
    // Deprecated call patterns
    //////////////////////////////////////////
    /**
     * @deprecated This call pattern is going away
     */
    subscribe(next: null | undefined, error: null | undefined, complete: () => void): Unsubscribable;
    /**
     * @deprecated This call pattern is going away
     */
    subscribe(next: null | undefined, error: (error: any) => void, complete?: () => void): Unsubscribable;
    /**
     * @deprecated This call pattern is going away
     */
    subscribe(next: (value: T) => void, error: null | undefined, complete: () => void): Unsubscribable;
    /**
     * @deprecated This call pattern is going away
     */
    subscribe(next?: (value: T) => void, error?: (error: any) => void, complete?: () => void): Unsubscribable;


    ////////////////////////////////////////////
    // Impl
    ////////////////////////////////////////////
    subscribe(...args: any[]): Unsubscribable {
        return {
            unsubscribe() {}
        };
    }
}


function somethingThatTakesSubscribable<T>(arg: Subscribable<T>): T {
    return null!;
}

/////////////////////////////////////
// Our failed expectation here
// (it's unknown)
/////////////////////////////////////
const result = somethingThatTakesSubscribable(new Observable<number>()); // $ExpectType number

🙁 Actual behavior

result is unknown above.

🙂 Expected behavior

result would be number.

从链接的 TypeScript Playground 开始，复现传递给 somethingThatTakesSubscribable 的 Observable 的推断结果。调查拆分后的 overload（包括已弃用的签名）如何与 Subscribable 进行比较。完成的标准是同一个示例将 result 推断为 number 而不是 unknown，并且覆盖报告的 overload 模式。