1// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s 2 3int f() __attribute__((warn_unused_result)); 4 5struct S { 6 void t() const; 7}; 8S g1() __attribute__((warn_unused_result)); 9S *g2() __attribute__((warn_unused_result)); 10S &g3() __attribute__((warn_unused_result)); 11 12void test() { 13 f(); // expected-warning {{ignoring return value}} 14 g1(); // expected-warning {{ignoring return value}} 15 g2(); // expected-warning {{ignoring return value}} 16 g3(); // expected-warning {{ignoring return value}} 17 18 (void)f(); 19 (void)g1(); 20 (void)g2(); 21 (void)g3(); 22 23 if (f() == 0) return; 24 25 g1().t(); 26 g2()->t(); 27 g3().t(); 28 29 int i = f(); 30 S s1 = g1(); 31 S *s2 = g2(); 32 S &s3 = g3(); 33 const S &s4 = g1(); 34} 35 36struct X { 37 int foo() __attribute__((warn_unused_result)); 38}; 39 40void bah() { 41 X x, *x2; 42 x.foo(); // expected-warning {{ignoring return value}} 43 x2->foo(); // expected-warning {{ignoring return value}} 44} 45 46namespace warn_unused_CXX11 { 47class Status; 48class Foo { 49 public: 50 Status doStuff(); 51}; 52 53struct [[clang::warn_unused_result]] Status { 54 bool ok() const; 55 Status& operator=(const Status& x); 56 inline void Update(const Status& new_status) { 57 if (ok()) { 58 *this = new_status; //no-warning 59 } 60 } 61}; 62Status DoSomething(); 63Status& DoSomethingElse(); 64Status* DoAnotherThing(); 65Status** DoYetAnotherThing(); 66void lazy() { 67 Status s = DoSomething(); 68 if (!s.ok()) return; 69 Status &rs = DoSomethingElse(); 70 if (!rs.ok()) return; 71 Status *ps = DoAnotherThing(); 72 if (!ps->ok()) return; 73 Status **pps = DoYetAnotherThing(); 74 if (!(*pps)->ok()) return; 75 76 (void)DoSomething(); 77 (void)DoSomethingElse(); 78 (void)DoAnotherThing(); 79 (void)DoYetAnotherThing(); 80 81 DoSomething(); // expected-warning {{ignoring return value}} 82 DoSomethingElse(); 83 DoAnotherThing(); 84 DoYetAnotherThing(); 85} 86 87template <typename T> 88class [[clang::warn_unused_result]] StatusOr { 89}; 90StatusOr<int> doit(); 91void test() { 92 Foo f; 93 f.doStuff(); // expected-warning {{ignoring return value}} 94 doit(); // expected-warning {{ignoring return value}} 95 96 auto func = []() { return Status(); }; 97 func(); // expected-warning {{ignoring return value}} 98} 99} 100 101namespace PR17587 { 102struct [[clang::warn_unused_result]] Status; 103 104struct Foo { 105 Status Bar(); 106}; 107 108struct Status {}; 109 110void Bar() { 111 Foo f; 112 f.Bar(); // expected-warning {{ignoring return value}} 113}; 114 115} 116 117namespace PR18571 { 118// Unevaluated contexts should not trigger unused result warnings. 119template <typename T> 120auto foo(T) -> decltype(f(), bool()) { // Should not warn. 121 return true; 122} 123 124void g() { 125 foo(1); 126} 127} 128 129namespace std { 130class type_info { }; 131} 132 133namespace { 134// The typeid expression operand is evaluated only when the expression type is 135// a glvalue of polymorphic class type. 136 137struct B { 138 virtual void f() {} 139}; 140 141struct D : B { 142 void f() override {} 143}; 144 145struct C {}; 146 147void g() { 148 // The typeid expression operand is evaluated only when the expression type is 149 // a glvalue of polymorphic class type; otherwise the expression operand is not 150 // evaluated and should not trigger a diagnostic. 151 D d; 152 C c; 153 (void)typeid(f(), c); // Should not warn. 154 (void)typeid(f(), d); // expected-warning {{ignoring return value}} expected-warning {{expression with side effects will be evaluated despite being used as an operand to 'typeid'}} 155 156 // The sizeof expression operand is never evaluated. 157 (void)sizeof(f(), c); // Should not warn. 158 159 // The noexcept expression operand is never evaluated. 160 (void)noexcept(f(), false); // Should not warn. 161} 162} 163