Comparing to string literals should be the same as comparing to consts of the same type

[davidswinegar]

Paste the following into try flow:

// @flow

const stringLiteral: 'STRING' = 'STRING'

const test = (type: 'STRING' | 'NUM') => {
    if (type === stringLiteral) {
        (type: 'STRING') // does error, but should not.
    }
    if (type === 'STRING') {
        (type: 'STRING') // A-OK
    }
};

The above code errors, but it should not. The type of stringLiteral is the string literal 'STRING' (not string) and it cannot be changed, so comparisons should work the same as comparing to a string literal. However, it does not.

[davidswinegar]

Update: this also occurs with object properties.

// @flow

const x: {stringLiteral: 'STRING'} = {
  stringLiteral: 'STRING'
};

const test = (type: 'STRING' | 'NUM') => {
    if (type === x.stringLiteral) {
        (type: 'STRING') // does error, but should not.
    }
    if (type === 'STRING') {
        (type: 'STRING') // A-OK
    }
};