Emits undefined for unknown types in declaration file

[tjoskar]

TypeScript Version:

1.7.5 / nightly (1.9.0-dev.20160221)

Code

Lets say I want to export some empty arrays:

// test.ts
export default {
  foo: [],
  bar: [],
  baz: []
}

and I want to generate a definition file for it:

> tsc test.ts --module commonjs -d

Expected behavior:

declare var _default: {
    foo: any[];
    bar: any[];
    baz: any[];
};
export default _default;

I expect the type to be any since the compiler don't know anything about the type.

Actual behavior:

declare var _default: {
    foo: undefined[];
    bar: undefined[];
    baz: undefined[];
};
export default _default;

Instead, I get undefined which is an invalid type (Error: can not find name 'undefined').

This seems like a bug?

Thanks and keep up the good work, I can't wait for version 2.0.

[Arnavion]

Perhaps the same underlying cause as #6524

[DanielRosenwasser]

It sounds like a default export should acquire the widened type of its RHS. The same issue exists for export = declarations.

export = {
    foo: []
}