Private `[Symbol.asyncIterator]` and `[Symbol.iterator]` methods incorrectly reported as unused

TypeScript Version: 4.2.0-dev.20201219

Search Terms:

Symbol.iterator Symbol.asyncIterator

Code

export class Polling {
  private async *[Symbol.asyncIterator]() {}
  private *[Symbol.iterator]() {}

  async loop() {
    for await (const updates of this) {
      void updates
    }
  }
  syncLoop() {
    for (const updates of this) {
      void updates
    }
  }
}

Expected behavior:
No errors.

Actual behavior:

'[Symbol.asyncIterator]' is declared but its value is never read.
'[Symbol.iterator]' is declared but its value is never read.

Playground Link

Start with the provided TypeScript 4.2.0-dev reproduction in the Playground, using noUnusedLocals and the async and sync iterator loops. Trace the unused-member diagnostics for the private [Symbol.asyncIterator] and [Symbol.iterator] methods. Done means the reproduction reports no errors while preserving unused-local diagnostics elsewhere.