TS infer type for class static field with error

[Frezc]

TypeScript Version: 3.9.7

Search Terms:

Code

// file a.ts
export class A {
    static foo() {}
}

// file b.ts
import { A } from './a';
export class B extends A {}

// file index.ts
import { B } from './b';
export const foo = B.foo;

Expected behavior:
output declaretion files with no errors.

Actual behavior:

// in index.d.ts
export declare const foo: typeof import("./a").A.foo;
// Namespace '"<build_path>/a"' has no exported member 'A'.ts(2694)

Playground Link:
https://github.com/Frezc/classstatictypeinfer-repro

Related Issues:

[RyanCavanaugh]

@weswigham we build these .d.ts files
a.d.ts

export declare class A {
    static foo(): void;
}

b.d.ts

import { A } from './a';
export declare class B extends A {
}

index.d.ts

export declare const foo: typeof import("./a").A.foo;

which raises an error if you try to build the .d.ts files together:

index.d.ts:1:48 - error TS2694: Namespace '"C:/Throwaway/classstatictypeinfer-repro/build/a"' has no exported member 'A'.

1 export declare const foo: typeof import("./a").A.foo;
                                                 ~

[weswigham]

Huh. The declaration files look fine (ie, that type should resolve) so it must be a name resolution bug of some kind.

[RyanCavanaugh]

FWIW

export declare const foo: typeof import("./a")["A"]["foo"];

works

[Frezc]

FYI

It's irrelative with class inheritance.

Another repro:

// file a.ts
export class A {
    static foo() {}
}

// file b.ts
import { A } from './a';
export const foo = A.foo;

// file index.ts
import { foo } from './b';
export const bar = foo;

Temporary solution

1. Add import for class A

// in index.ts
import { A } from './a'; // <----- add this
import { B } from './b';
export const foo = B.foo;

generated declaretion

import { A } from './a';
export declare const foo: typeof A.foo;

2. Define namespace A

// in a.ts
export class A {
    static foo() {}
}

// add this
export namespace A {
    export type foo = typeof A.foo;
}