Missing 'used before declaration' error with IIFE

[ajafff]

TypeScript Version: 3.2.1

Search Terms:

Code

class C {
    a = (() => this.b)();
    b = '';
}

Expected behavior:

Error Property 'b' is used before its initialization.
Control flow analysis inlines IIFEs, but it seems the use-before-declare check doesn't.

Actual behavior:

No error

Playground Link: https://agentcooper.github.io/typescript-play/#code/MYGwhgzhAEDC0G8BQ1XTNAvNAFDglFgHzQAuAFgJYQB0ARvgQNwpp1bQDknLAvkA

Related Issues: Found while investigating #29125

[belozer]

TypeScript Version: 3.8.2

class Test {
  dataSource = this.prepare()
  prepare() { return this.getData }
  getData = () => { }
}

Expected behavior:

Error Property 'getData' is used before its initialization.

Actual behavior:

No error

Playground Link:

http://www.typescriptlang.org/play/index.html#code/MYGwhgzhAEAqCmEAu0DeAoa0AmYlgGUB7AVwCdh5oBeaJACwEsIA6ABzPjbE4AoBKTNA5ce8AWmick5AHZ0mrAObwkAETxhoAXyEr1mmtAnUAfJN3agA

[MatthiasvB]

We are now at TS v4.7 and this is still there

Playground