Unexpected type reference between divided modules

[vvakame]

TypeScript Version: 2.0.2

Code

sampleA.ts

{
    // local types
    type Data = string | boolean;
    let obj: Data = true;
    console.log(obj);
}
export { }

sampleB.ts

let v = "str" || true;

export { v }

tsconfig.json

{
    "compilerOptions": {
        "declaration": true,
        "skipDefaultLibCheck": true
    },
    "include": [
        "sample*.ts"
    ]
}

This is minimal settings.
When "declaration": true and "skipDefaultLibCheck": true, this issue is occured.

Expected behavior:

We can compile this code.

Actual behavior:

$ tsc -v
Version 2.0.2
$ tsc -p ./
sampleB.ts(1,5): error TS4023: Exported variable 'v' has or is using name 'Data' from external module "/private/tmp/hogehogehoge/sampleA" but cannot be named.

[vladima]

at glance root cause of the issue is caching of union types: type of Data in sampleA.ts is string | boolean and it is the same with type of v in sampleB.ts. However type in the first case has associated alias which is not visible if the same type is reused in different context.

Why error does not repro without skipDefaultLibCheck - I guess some declaration in lib.d.ts has the same type. This type will be put in the cache and used for both sampleA.ts and sampleB.ts will

// CC @ahejlsberg