tests/ui/consts/const-for-feature-gate.rs - third_party/github.com/rust-lang/rust - Git at Google

 // gate-test-const_for

 const _: () = {
     for _ in 0..5 {}
     //~^ ERROR cannot use `for`
     //~| ERROR cannot use `for`
 };

 fn main() {}
	// gate-test-const_for

	const _: () = {
	for _ in 0..5 {}
	//~^ ERROR cannot use `for`
	//~\| ERROR cannot use `for`
	};

	fn main() {}