src/test/rustdoc/issue-30252.rs - third_party/github.com/rust-lang/rust - Git at Google

 // compile-flags:--test --cfg feature="bar"

 /// ```rust
 /// assert_eq!(cfg!(feature = "bar"), true);
 /// ```
 pub fn foo() {}
	// compile-flags:--test --cfg feature="bar"

	/// ```rust
	/// assert_eq!(cfg!(feature = "bar"), true);
	/// ```
	pub fn foo() {}