128 lines · cpp
1// RUN: %clang_analyze_cc1 -std=c++17 -analyzer-checker=core,deadcode -verify %s2 3typedef unsigned long size_t;4 5// Machinery required for custom structured bindings decomposition.6namespace std {7template <class T> class tuple_size;8template <class T>9 constexpr size_t tuple_size_v = tuple_size<T>::value;10template <size_t I, class T> class tuple_element;11 12template<class T, T v>13struct integral_constant {14 static constexpr T value = v;15 typedef T value_type;16 typedef integral_constant type;17 constexpr operator value_type() const noexcept { return value; }18};19}20 21struct S {22 int a;23 double b;24 S(int a, double b) : a(a), b(b) {};25};26 27S GetNumbers();28 29int used_binding() {30 const auto [a, b] = GetNumbers(); // no-warning31 return a + b; 32}33 34void no_warning_on_copy(S s) {35 // Copy constructor might have side effects.36 const auto [a, b] = s; // no-warning37}38 39 40int unused_binding_ignored() {41 const auto [a, b] = GetNumbers(); // expected-warning{{Value stored to '[a, b]' during its initialization is never read}}42 return 0;43}44 45int unused_binding_liveness_required() {46 auto [a2, b2] = GetNumbers(); // expected-warning{{Value stored to '[a2, b2]' during its initialization is never read}}47 a2 = 10;48 b2 = 20;49 return a2 + b2;50}51 52int kill_one_binding() {53 auto [a, b] = GetNumbers(); // no-warning54 a = 100;55 return a + b;56 57}58 59int kill_one_binding2() {60 auto [a, b] = GetNumbers(); // expected-warning{{Value stored to '[a, b]' during its initialization is never read}}61 a = 100;62 return a;63}64 65void use_const_reference_bindings() {66 const auto &[a, b] = GetNumbers(); // no-warning67}68 69void use_reference_bindings() {70 S s(0, 0);71 auto &[a, b] = s; // no-warning72 a = 200;73}74 75int read_through_pointer() {76 auto [a, b] = GetNumbers(); // no-warning77 int *z = &a;78 return *z;79}80 81auto [globalA, globalB] = GetNumbers(); // no-warning, globals82auto [globalC, globalD] = GetNumbers(); // no-warning, globals83 84void use_globals() {85 globalA = 300; // no-warning86 globalB = 200;87}88 89struct Mytuple {90 int a;91 int b;92 93 template <size_t N>94 int get() const {95 if constexpr (N == 0) return a;96 else if constexpr (N == 1) return b;97 }98};99 100namespace std {101 template<>102 struct tuple_size<Mytuple>103 : std::integral_constant<size_t, 2> {};104 105 template<size_t N>106 struct tuple_element<N, Mytuple> {107 using type = int;108 };109}110 111void no_warning_on_tuple_types_copy(Mytuple t) {112 auto [a, b] = t; // no-warning113}114 115Mytuple getMytuple();116 117void deconstruct_tuple_types_warning() {118 // The initializers reference the decomposed region, so the warning is not reported119 // FIXME: ideally we want to ignore that the initializers reference the decomposed region, and report the warning,120 // though the first step towards that is to handle DeadCode if the initializer is CXXConstructExpr.121 auto [a, b] = getMytuple(); // no-warning122}123 124int deconstruct_tuple_types_no_warning() {125 auto [a, b] = getMytuple(); // no-warning126 return a + b;127}128