1 // RUN: %clang_analyze_cc1 -std=c++17 -analyzer-checker=core,deadcode -verify %s
2
3 typedef unsigned long size_t;
4
5 // Machinery required for custom structured bindings decomposition.
6 namespace std {
7 template <class T> class tuple_size;
8 template <class T>
9 constexpr size_t tuple_size_v = tuple_size<T>::value;
10 template <size_t I, class T> class tuple_element;
11
12 template<class T, T v>
13 struct integral_constant {
14 static constexpr T value = v;
15 typedef T value_type;
16 typedef integral_constant type;
operator value_typestd::integral_constant17 constexpr operator value_type() const noexcept { return value; }
18 };
19 }
20
21 struct S {
22 int a;
23 double b;
SS24 S(int a, double b) : a(a), b(b) {};
25 };
26
27 S GetNumbers();
28
used_binding()29 int used_binding() {
30 const auto [a, b] = GetNumbers(); // no-warning
31 return a + b;
32 }
33
no_warning_on_copy(S s)34 void no_warning_on_copy(S s) {
35 // Copy constructor might have side effects.
36 const auto [a, b] = s; // no-warning
37 }
38
39
unused_binding_ignored()40 int 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
unused_binding_liveness_required()45 int 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
kill_one_binding()52 int kill_one_binding() {
53 auto [a, b] = GetNumbers(); // no-warning
54 a = 100;
55 return a + b;
56
57 }
58
kill_one_binding2()59 int 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
use_const_reference_bindings()65 void use_const_reference_bindings() {
66 const auto &[a, b] = GetNumbers(); // no-warning
67 }
68
use_reference_bindings()69 void use_reference_bindings() {
70 S s(0, 0);
71 auto &[a, b] = s; // no-warning
72 a = 200;
73 }
74
read_through_pointer()75 int read_through_pointer() {
76 auto [a, b] = GetNumbers(); // no-warning
77 int *z = &a;
78 return *z;
79 }
80
81 auto [globalA, globalB] = GetNumbers(); // no-warning, globals
82 auto [globalC, globalD] = GetNumbers(); // no-warning, globals
83
use_globals()84 void use_globals() {
85 globalA = 300; // no-warning
86 globalB = 200;
87 }
88
89 struct Mytuple {
90 int a;
91 int b;
92
93 template <size_t N>
getMytuple94 int get() const {
95 if constexpr (N == 0) return a;
96 else if constexpr (N == 1) return b;
97 }
98 };
99
100 namespace 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
no_warning_on_tuple_types_copy(Mytuple t)111 void no_warning_on_tuple_types_copy(Mytuple t) {
112 auto [a, b] = t; // no-warning
113 }
114
115 Mytuple getMytuple();
116
deconstruct_tuple_types_warning()117 void deconstruct_tuple_types_warning() {
118 auto [a, b] = getMytuple(); // expected-warning{{Value stored to '[a, b]' during its initialization is never read}}
119 }
120
deconstruct_tuple_types_no_warning()121 int deconstruct_tuple_types_no_warning() {
122 auto [a, b] = getMytuple(); // no-warning
123 return a + b;
124 }
125