Interface cannot override predicate return type with boolean

[mjbvz]

🔎 Search Terms

• must be a type predicate

🕗 Version & Regression Information

• This is a crash
• This changed between versions 5.4.5 and 5.5.0-dev.20240415

⏯ Playground Link

https://www.typescriptlang.org/play?ts=5.5.0-dev.20240415#code/JYOwLgpgTgZghgYwgAgGIHt3IN4CgCQwAzhugBQAeAXMnCAJ4CUNYAFsch6QNy4C+uXKEixEKAEJwoyCBUggAJkTSYcBYqUo06TFlACuEXsj5A

💻 Code

interface Foo {
	isFoo(x: any): this is Foo;
}

interface Bar extends Foo {
	isFoo(x: any): true;
}

🙁 Actual behavior

In bar, see:

Signature '(x: any): true' must be a type predicate

🙂 Expected behavior

No error

Additional information about the issue

Encountering this in the VS Code repo. Seems like an unexpected regression

[gabritto]

Caused by #57341.

[typescript-bot]

This issue has been marked as "Working as Intended" and has seen no recent activity. It has been automatically closed for house-keeping purposes.