Spurious "index signature incompatible" error for function returning an object literal expression

[NoelAbrahams]

Hi,

TypeScript Version: 1.1.0.1

Here is the repro:

interface Foo {
    [index: string]: any;
    name: string;       
}

// Case 1: no error
var f1: Foo = {
        name: 'FooOne',
};

// Case 2: no error 
var f2 = function(): Foo {
    return {
        name: 'FooTwo',
    };
}

// Case 3:
// Compiler Error: error TS2322: Build: Type '{ name: string; }' is not 
   // assignable to type 'Foo'
// IDE Error: Cannot convert '{ name: string; }' to 'Foo':  Index signatures 
   // of types '{ name: string; }' and 'Foo' are incompatible.
var f3 = (): Foo => ({
        name: 'FooThree',
});

The expected result is there to be no error, since the object literal in the last case is indexable by string to return any.

[basarat]

The expected result is there to be no error

👍 since f3 is effectively same as f2.

[RyanCavanaugh]

Contextual types do not flow into parentheses, so the return expression of the function expression initializing f3 is not contextually typed by Foo.

See also http://stackoverflow.com/questions/22077023/why-cant-i-indirectly-return-an-object-literal-to-satisfy-an-index-signature-re