Incorrect declaration emit for allowJs JavaScript class with static members imported from other files

[cspotcode]

TypeScript Version: 3.7.0-dev.20191002

Search Terms:

Code

Emitted index.d.ts from these JS files using --declaration --allowJs has an avoidable semantic error. It looks like the compiler usually avoids this error, but in this particular case it doesn't.

// foo.js
function foo() {}
export {foo}

// index.js
import {foo} from './foo'

export {MyClass}
function MyClass() {}
MyClass.prototype = {
 method() {}
}
MyClass.foo = foo

Expected behavior:

This declaration is emitted:

// index.d.ts
export function MyClass(): void;
export class MyClass {
 method(): void;
}
export namespace MyClass {
 export { foo };
 import { foo } from "./foo";
}
export {};

Actual behavior:

This declaration is emitted:

// index.d.ts
export function MyClass(): void;
export class MyClass {
 method(): void;
}
export namespace MyClass {
 export { foo };
}
declare var foo: typeof foo; // <-- foo circularly references self
import { foo } from "./foo"; // <-- import foo conflicts with var foo
export {};
//# sourceMappingURL=index.d.ts.map

It appears to be triggered by the combination of both function MyClass and MyClass.prototype = assignment. Removing one or the other fixes the bug, so that the import {foo} from './foo'; is nested within export namespace MyClass as in the "expected behavior" above.

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Related Issues:

[weswigham]

To the OP: This should now be fixed on master (so should go out in the next nightly) and in the next 3.7 cut (which should be final release at this point?), by #34786 (essentially a dupe of one of the reports in #33626)

Your expected emit is a lil off though; we emit:

//// [foo.d.ts]
export function foo(): void;
//// [index.d.ts]
export function MyClass(): void;
export class MyClass {
 method(): void;
}
export namespace MyClass {
 export { foo };
}
import { foo } from "./foo";

you're not allowed to have an import statement in a namespace, and the top-level export {}; is unneeded in your example (as something in the file is exported, so the file's definitely a module, and there's no privates which need their scoping preserved)~

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.