test/ClangImporter/Inputs/custom-modules/UnimportableMembersUser.h - third_party/swift - Git at Google

 @import UnimportableMembers;

 @interface DesignatedInitializerInAnotherModule (/*evil class extension*/)
 - (instancetype)initFromOtherModule:(long)x __attribute__((objc_designated_initializer));
 @end
	@import UnimportableMembers;

	@interface DesignatedInitializerInAnotherModule (/evil class extension/)
	- (instancetype)initFromOtherModule:(long)x __attribute__((objc_designated_initializer));
	@end