No TSC error for duplicate dynamic keys with static readonly values

[tompere]

TypeScript Version: 3.1.0-dev.20180809

Search Terms: dynamic key duplicate identifier

Code

const X = 'x'

enum Y {
  ONE = 'one',
  TWO = 'one'
}

// static key - 'duplicate identifier' error

const obj1 = {
  'y': 'wham',
  'y': 'bam' // as expected, tsc error `Duplicate identifier ''y''`
}

const obj2 = {
  y: 'wham',
  y: 'bam' // as expected, tsc error `Duplicate identifier 'y'`
}

// [the bug] dynamic key - no 'duplicate identifier' error

const obj3 = {
  [X]: 'wham',
  [X]: 'bam' // no tsc error!
}

const obj4 = {
  [Y.ONE]: 'wham',
  [Y.TWO]: 'bam' // no tsc error!
}

Expected behavior:
When assigning duplicate dynamic keys to plain objects, which can be statically inferred (e.g. enums or const with primitive type) - tsc should show a compilation error.

Actual behavior:
no compilation error.

Playground Link:
a long long long playground link ...

Related Issues: N/A

[AlCalzone]

Why should this be an error?

enum Y {
    ONE = 'one',
    TWO = 'two'
}

const obj4 = {
    [Y.ONE]: 'wham',
    [Y.TWO]: 'bam' // no tsc error!
}

[tompere]

@AlCalzone you're right.
updated:

enum Y {
    ONE = 'one',
    TWO = 'one'
}

[ajafff]

Duplicate of #25758

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.