llvm-project/clang/test/SemaObjC/protocols-suppress-conformance.m

// RUN: %clang_cc1  -triple x86_64-apple-darwin11 -fsyntax-only -verify %s -Wno-objc-root-class

// Mark this protocol as requiring all of its methods and properties
// to be explicitly implemented in the adopting class.
__attribute__((objc_protocol_requires_explicit_implementation))
@protocol Protocol
- (void) theBestOfTimes; // expected-note {{method 'theBestOfTimes' declared here}}
@property (readonly) id theWorstOfTimes;
@end

// In this example, ClassA adopts the protocol.  We won't
// provide the implementation here, but this protocol will
// be adopted later by a subclass.
@interface ClassA <Protocol>
- (void) theBestOfTimes;
@property (readonly) id theWorstOfTimes;
@end

// This class subclasses ClassA (which adopts 'Protocol'),
// but does not provide the needed implementation.
@interface ClassB : ClassA <Protocol> // expected-note {{required for direct or indirect protocol 'Protocol'}}
@end

@implementation ClassB // expected-warning {{method 'theBestOfTimes' in protocol not implemented}}
@end

// Test that inherited protocols do not get the explicit conformance requirement.
@protocol Inherited
- (void) fairIsFoul;
@end

__attribute__((objc_protocol_requires_explicit_implementation))
@protocol Derived <Inherited>
- (void) foulIsFair; // expected-note {{method 'foulIsFair' declared here}}
@end

@interface ClassC <Inherited>
@end

@interface ClassD : ClassC <Derived> // expected-note {{required for direct or indirect protocol 'Derived'}}
@end

@implementation ClassD // expected-warning {{method 'foulIsFair' in protocol not implemented}}
@end

// Test that the attribute is used correctly.
__attribute__((objc_protocol_requires_explicit_implementation(1+2))) // expected-error {{attribute takes no arguments}}
@protocol AnotherProtocol @end

// Cannot put the attribute on classes or other non-protocol declarations.
__attribute__((objc_protocol_requires_explicit_implementation)) // expected-error {{attribute only applies to Objective-C protocols}}
@interface AnotherClass @end

__attribute__((objc_protocol_requires_explicit_implementation)) // expected-error {{attribute only applies to Objective-C protocols}}
int x;