"used before being assigned" fires on LHS inside parens/type assertion

[jakebailey]

🔎 Search Terms

used before being assigned cast type assertion left side LHS parens parentheses

🕗 Version & Regression Information

• This is the behavior changed in 5.7

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.9.0-dev.20250725#code/CYUwxgNghgTiAEAzArgOzAFwJYHtX1AGcwYsAjEAClSgFsQAueQjU1AcwBolUnKBKeAF4AfPABuOLMH5NJ0gLAAoZaEiwEKdNjzwKiHHACiUMAAtKiXvAHCx8mXKnAA3MtXhoceOsKF4AMo49BhmWBzwAN7K8Eg4OAJMqMi0FDBuSgC+7kpEJORUAESF3LaiUTHwECAYetBmTEEhYRwZlfqGICbmlGVi0UqxsZRk9fBQ-lCoAJ6CQj7QfvAA6jgA7lGZGbGZ-Mq7OR7EpBSUxaVz-ZXVtaNQDYHBNS3sbYN6IAbGphZ9Fe-DO5mOYLCb+VYbSJbSoHLJ7JRAA

💻 Code

declare function describe(name: string, fn: () => void): void

declare function beforeEach(fn: () => void): void;

declare class Something {
  foo(): number;
}

describe("", () => {
  let blah: Something;

  beforeEach(() => {
    (blah as any) = class Wow {};
  })
})

describe("", () => {
  let blah: Something;

  beforeEach(() => {
    (blah) = class Wow {};
  })
})

🙁 Actual behavior

Both assignments error with is used before being assigned.

🙂 Expected behavior

Neither should, as they are writes.

Additional information about the issue

No response

[jakebailey]

This is actually new in 5.6.