Const with non-widening type as dynamic object literal key

[arusakov]

TypeScript Version: master (c76a3a6)

Code

const x: 'x' = 'x';
const y: 'y' = 'y';

const z = {
  [x]: y
};

Expected behavior:
z has type { x: "y" }

Actual behavior:
z has type { [x: string]: 'y' }. It's inconsistency.

[NN---]

Did you mean "z has type"?;)

[arusakov]

@NN--- thank you

[mhegazy]

This is a duplicate of #5579.
The issue here is that the compiler does things in phases. the first phase, binding, it setts the names of properties on a type/symbol. the second is type resolution, that is when it knows about types of symbols. this change requires these two phases to be interleaved in a way, which is not a small change.