`typeof` does not get concatenated string type

[Lodin]

The pattern I used in code below is originally from Redux. When I use strings "as is", without any concatenation, it works. But when I try to move common part (prefix) out, it brokes. Intuitively I assume that since prefix and other parts are constants typeof should get united type.

TypeScript Version: 2.7.0-dev.20171213

Code

const prefix = 'prefix';

const TOKEN1 = `${prefix}/token1`;
const TOKEN2 = `${prefix}/token2`;

interface Wrapper {
    type: string;
}

interface WrapperToken1 extends Wrapper { 
    test: string;
    type: typeof TOKEN1;
}

interface WrapperToken2 extends Wrapper {
    other: number;
    type: typeof TOKEN2;
 }

function test(wrapper: WrapperToken1 | WrapperToken2): string { 
    switch (wrapper.type) {
        case TOKEN1:
            return wrapper.test;
        case TOKEN2:
            return wrapper.other.toString();
        default:
            return '';
    }
}

Expected behavior:
No errors raised.

Actual behavior:
Raises errors:

Property 'test' does not exist on type 'WrapperToken1 | WrapperToken2'.
  Property 'test' does not exist on type 'WrapperToken2'.

Property 'other' does not exist on type 'WrapperToken1 | WrapperToken2'.
  Property 'other' does not exist on type 'WrapperToken1'.

Duplicate of #12940 -- currently we never compute string literal types for concatenations.

[Lodin]

@Andy-MS Thanks! Should I close this issue?

I think so, you could add your use case as a comment to that issue.