Accessing protected computed property does not produce a compiler error

🔎 Search Terms

protected computed no error bug

🕗 Version & Regression Information

This is the behavior in every version I tried (v3.3.3333, v4.0.5, v5.7.3), and I reviewed the FAQ for entries about Common "Bugs" That Aren't Bugs

⏯ Playground Link

https://tsplay.dev/wjdn7m

💻 Code

declare class Foo {
  protected readonly baz = 42
}

declare class Bar {
  readonly foo: Foo
}

declare const bar: Bar

// @ts-expect-error
console.log(bar.foo["baz"].toFixed(2))

🙁 Actual behavior

• (without // @ts-expect-error): No errors
• (with // @ts-expect-error): Compiler error Unused '@ts-expect-error' directive

🙂 Expected behavior

• (without // @ts-expect-error): Compiler error Property […] is protected and only accessible within class 'Foo' and its subclasses
• (with // @ts-expect-error): No errors

Additional information about the issue

No response

Reproduce the behavior from the TypeScript Playground link using the provided Foo, Bar, and bracket-access example. Start by tracing compiler handling of protected-property access through an indexed access, then add coverage for the expected diagnostic and verify that the @ts-expect-error directive is consumed.