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Description

Bug Report

Removing an overload member Controller.handle from Controller causes a compilation error.

🔎 Search Terms

Interface overload
Member Type Parameter
Works When Removing overload

⏯ Playground Link

Playground

💻 Code

Code below compiles

export interface Controller {
  handle<T>(httpRequest: HttpRequest<T>): HttpResponse<T>;
  handle<TRequest, TResponse>(httpRequest: HttpRequest<TRequest>): HttpResponse<TResponse>;
}

Code below does not compile

export interface Controller {
  // handle<T>(httpRequest: HttpRequest<T>): HttpResponse<T>;
  handle<TRequest, TResponse>(httpRequest: HttpRequest<TRequest>): HttpResponse<TResponse>;
}

Code below does not compile

export interface Controller {
  handle<T>(httpRequest: HttpRequest<T>): HttpResponse<T>;
  // handle<TRequest, TResponse>(httpRequest: HttpRequest<TRequest>): HttpResponse<TResponse>;
}

🙁 Actual behavior

Code does not compile when removing any of the overloads.

🙂 Expected behavior

Since having an overload in Controller.handle works, having just one member with the correct signature should also work.

Additional Info

Stack Overflow Question

Contributor guide

Research direction: Investigate the TypeScript compiler's handling of overloaded generic interface members, focusing on the checker's overload resolution logic. Reproduce the issue with the provided playground link and trace the error path.
Tech stack: typescript
Domain: compilers
Issue type: Bug
Difficulty: 4
Estimated time: 3-5 days
Activity status: Active
Clarity: Clear
Prerequisites: TypeScriptGit
Newbie friendliness: 20