llvm-project/clang/test/SemaObjC/method-conflict-2.m

// RUN: %clang_cc1 -Wmethod-signatures -fsyntax-only -verify -Wno-objc-root-class %s

@interface A @end
@interface B : A @end

@interface Test1 {}
- (void) test1:(A*) object; // expected-note {{previous definition is here}} 
- (void) test2:(B*) object;
@end

@implementation Test1
- (void) test1:(B*) object {} // expected-warning {{conflicting parameter types in implementation of 'test1:': 'A *' vs 'B *'}}
- (void) test2:(A*) object {}
@end

@interface Test2 {}
- (void) test1:(id) object; // expected-note {{previous definition is here}} 
- (void) test2:(A*) object;
@end

@implementation Test2
- (void) test1:(A*) object {} // expected-warning {{conflicting parameter types in implementation of 'test1:': 'id' vs 'A *'}}
- (void) test2:(id) object {}
@end

@interface Test3 {}
- (A*) test1;
- (B*) test2; // expected-note {{previous definition is here}} 
@end

@implementation Test3
- (B*) test1 { return 0; }
- (A*) test2 { return 0; } // expected-warning {{conflicting return type in implementation of 'test2': 'B *' vs 'A *'}}
@end

// The particular case of overriding with an id return is white-listed.
@interface Test4 {}
- (id) test1;
- (A*) test2;
@end
@implementation Test4
- (A*) test1 { return 0; } // id -> A* is rdar://problem/8596987
- (id) test2 { return 0; }
@end