TS2.7 produces illegal .d.ts files for objects with computed property names

[mprobst]

TypeScript Version: 2.7.0-dev.20180110

Code

export const SOME_STRING = 'api-key';
export const DEFAULTS = {
  [SOME_STRING]: 'some value',
};

Expected behavior:

Produce a valid .d.ts file.

Actual behavior:

Produces:

export declare const SOME_STRING = "api-key";
export declare const DEFAULTS: {
    [SOME_STRING]: string;
};

The declaration of [SOME_STRING]: string gives [ts] A computed property name in a type literal must directly refer to a built-in symbol.

[mhegazy]

Just to clarify.. you mean illegal in previous versions of the compiler.

[mprobst]

You are right. The bug I was trying to pin down is rather that you cannot create a type from DEFAULTS:

import {DEFAULTS} from './decl';
type z = typeof DEFAULTS;  // z is {}
type keys = keyof z;  // keys is never

[mprobst]

This might be related to #13042?

[mhegazy]

You are right. The bug I was trying to pin down is rather that you cannot create a type from DEFAULTS:

import {DEFAULTS} from './decl';
type z = typeof DEFAULTS;  // z is {}
type keys = keyof z;  // keys is never

I am not seeing this locally on typescript@next:

[mprobst]

I can repro the issue with TS2.6, but indeed not typescript@next, so seems fixed already (and we'll have to work around it for the TS2.6 migration).