Computed properties no throws if there is a duplicate

[cevek]

TypeScript Version: 3.0.0-dev.20180712

Search Terms:

Code

const A = 'a';
const x = {[A]: 1, [A]: 'b'} // x is {[A]: string}

Expected behavior:
Duplicate declaration error

Actual behavior:
No error

Playground Link: https://www.typescriptlang.org/play/#src=const%20A%20%3D%20'a'%3B%0D%0Aconst%20x%20%3D%20%7B%5BA%5D%3A%201%2C%20%5BA%5D%3A%201%7D%0D%0A

Related Issues:

[mhegazy]

Checking for duplicate declaration errors are done earlier in the process, by the time the compiler known the properties it is a bit late to report the errors

[cevek]

This is very sad

sometimes it works, from time to time

const A = 'a';
const x = {[A]: 1, [A]() {}} // Duplicate declaration '[A]'