@protocol foo;
@class itf;
// Expressions
typedef typeof(@"foo" "bar") objc_string;
typedef typeof(@encode(int)) objc_encode;
typedef typeof(@protocol(foo)) objc_protocol;
typedef typeof(@selector(noArgs)) objc_selector_noArgs;
typedef typeof(@selector(oneArg:)) objc_selector_oneArg;
typedef typeof(@selector(foo:bar:)) objc_selector_twoArg;
// Types.
typedef typeof(id<foo>) objc_id_protocol_ty;
typedef typeof(itf*) objc_interface_ty;
typedef typeof(itf<foo>*) objc_qual_interface_ty;