Regression in invalid-computed-prop detection about flow HOT 7 CLOSED

This is due to the fact that things like

declare const obj: {foo: string};
declare const key: string;
obj[key]

are never safe, and just returns any before. In the latest Flow version, we choose to start loudly error.

from flow.

I tried your initial example, locally over two files, and was not able to reproduce the error.

from flow.

I struggled a bit but I eventually understood what I did wrong.
Thanks for your answer, @SamChou19815!

from flow.

Well, there's still something bothering me.
What about this example:

enum MyEnum {
    ValFoo = 'foo',
    ValBar = 'bar'
}

declare const obj: {foo: string, bar: string};
declare const key: string;
obj[MyEnum.ValFoo as string]

Why doesn't it work, since MyEnum.ValFoo as string is indeed the string "foo"?

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In fact, I still don't understand the difference between (1):

type Dict<T> = {| [string]: T |};
export type BoolDict = Dict<bool>;

and (2):

export type BoolDict = {| [string]: bool |};

The following code does not work with (1) but is OK with (2):

const bd: BoolDict = { foo: true };
const k = 'foo';
const {[k]: v} = bd;

from flow.

The enum example is an issue with enum feature. The right solution is to support enum key rather than continue to allow this unsafe access.

In fact, I still don't understand the difference between (1):

type Dict<T> = {| [string]: T |};
export type BoolDict = Dict<bool>;

and (2):

export type BoolDict = {| [string]: bool |};

The following code does not work with (1) but is OK with (2):

const bd: BoolDict = { foo: true };
const k = 'foo';
const {[k]: v} = bd;

I am still unable to reproduce this? Can you provide a try-flow link?

from flow.

Unfortunately, I can't.
I think it has something to do with export & import and only fails when the code is spread across multiple files, because it works correctly in try-flow.

from flow.