Provide `declare` keyword support for class methods

Search Terms

declare, class, method

Suggestion

I know that declare keyword already support class properties. I've wonder if it is possiable to bring the support to class methods as well?

Use Cases

You override a method a, and there are some other methods that return the return value of a.

Examples

This is just a simple example describing my idea.

class BaseTag
{
    constructor(tag: string) {...}

    static fromString(tag: string): BaseTag
    {
        return new BaseTag(tag);
    }

    static fromNumber(tag: number): BaseTag
    {
        return this.fromString(tag.toString());
    }
}

class ExtendedTag extends BaseTag
{
    static fromString(tag: string): ExtendedTag
    {
        return new BaseTag(`Tag: ${ tag}`);
    }

    declare static fromNumber(tag: number): ExtendedTag;

    // // Without `declare` support
    // static fromNumber(tag: number): ExtendedTag
    // {
    //     return super.fromString(tag) as unknown as ExtendedTag;
    // }
}

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

The issue names no source file, test, or entry point. Start by comparing existing declare support for class properties with the requested static method syntax and clarify its type-checking and emit behavior. Done means the feature’s semantics are specified and covered by tests.