'Cannot find namespace ...' for type declarations using default-exported module import

[pcan]

I found a strange behaviour when importing a default-exported module from file1 and using it for variable/parameter/return value/whatever... type declarations in file2. Please note that the imported namespace is still visible and works correctly when I use it for variable definitions (e.g. invoking class constructor with new). See the code below:

file1.ts

export module a {
    export module b {
        export class MyClass {
            x: number = 10;
        }
    }
}

export default a.b;

file2.ts

import y from './file1';

function fn(): y.MyClass {      //warning here: Cannot find namespace 'y'.
    return new y.MyClass();     //it works here, no compiler warning
}

var a = fn();                   //works fine
var b: y.MyClass = fn();        //warning here: Cannot find namespace 'y'.

function fn2(i: y.MyClass) {    //warning here: Cannot find namespace 'y'.
}

Instead, for class expression (export default class {... in file1.ts) it works fine, both for type declarations and variable definitions.

[mhegazy]

looks like a duplicate of #4325.

The problem is the compiler will export all meanings of a name, iff it is an identifier and not a dotted name.. i.e:

export default a.b; // exports only the value a.b, no type or namespace

export default b; // exports all meanings of b, value, type and namespace

i agree that this is a wrong behavior. for now, use an alias to work around the issue:

export module a {
    export module b {
        export class MyClass {
            x: number = 10;
        }
    }
}

import _b = a.b;
export default _b;

[pcan]

Ok, thanks.