Bug Report

🔎 Search Terms

function top type callable spread never regression

🕗 Version & Regression Information

• This changed between versions 3.8.3 and 3.9.7

⏯ Playground Link

Playground link with relevant code

💻 Code

declare let foo: (...args: never) => void;
foo = (x: string) => {};
foo();  // no error

🙁 Actual behavior

foo() was permitted.

🙂 Expected behavior

foo() should not be permitted because it is unsafe. (...args: never) => unknown behaves as the top-type for all functions; all function types are assignable to it. So calling it will lead to unsafe behavior by functions expecting 1 or more arguments.