Destructuring with computed key does not do type inferring even for indexed types

[Jessidhia]

TypeScript Version: 2.4.0

Code

declare const textMap: {[key: string]: string}

function getText (input: string) {
  const {
      [input]: rawText = input
  } = textMap
  // rawText inferred as 'any' and not 'string'
}

Expected behavior:
rawText to be inferred as string

Actual behavior:
rawText inferred as any

---

As this is a destructuring pattern, it is actually not possible at all to declare the type of rawText other than by making rawText a let declaration first and running an destructuring expression, or otherwise writing equivalent code that does not use destructuring.

let rawText: string
({[input]: rawText = input} = textMap)

[rubiesonthesky]

It seems that rawText is been inferred as string now

declare const textMap: {[key: string]: string}

function getText (input: string) {
  const {
      [input]: rawText = input
//             ^?
  } = textMap
}

Workbench Repro

[typescript-bot]

👋 Hi, I'm the Repro bot. I can help narrow down and track compiler bugs across releases! This comment reflects the current state of this repro running against the nightly TypeScript.

---

Comment by @rubiesonthesky

⚠️ Assertions:

• const rawText: string

Historical Information

Version	Reproduction Outputs
5.0.2, 5.1.3, 5.2.2, 5.3.2, 5.4.2	⚠️ Assertions: const rawText: string