dead-stores.cpp revision 2827f5af018c515986ffb1779ec2e7246988f150 
1// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -analyze -analyzer-checker=deadcode.DeadStores -verify -Wno-unreachable-code %s
2// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -analyze -analyzer-store=region -analyzer-constraints=range -analyzer-checker=deadcode.DeadStores -verify -Wno-unreachable-code %s
3
4//===----------------------------------------------------------------------===//
5// Basic dead store checking (but in C++ mode).
6//===----------------------------------------------------------------------===//
7
8int j;
9void test1() {
10  int x = 4;
11
12  x = x + 1; // expected-warning{{never read}}
13
14  switch (j) {
15  case 1:
16    throw 1;
17    (void)x;
18    break;
19  }
20}
21
22//===----------------------------------------------------------------------===//
23// Dead store checking involving constructors.
24//===----------------------------------------------------------------------===//
25
26class Test2 {
27  int &x;
28public:
29  Test2(int &y) : x(y) {}
30  ~Test2() { ++x; }
31};
32
33int test2(int x) {
34  { Test2 a(x); } // no-warning
35  return x;
36}
37
38//===----------------------------------------------------------------------===//
39// Dead store checking involving CXXTemporaryExprs
40//===----------------------------------------------------------------------===//
41
42namespace TestTemp {
43  template<typename _Tp>
44  class pencil {
45  public:
46    ~pencil() throw() {}
47  };
48  template<typename _Tp, typename _Number2> struct _Row_base {
49    _Row_base(const pencil<_Tp>& x) {}
50  };
51  template<typename _Tp, typename _Number2 = TestTemp::pencil<_Tp> >
52  class row : protected _Row_base<_Tp, _Number2>     {
53    typedef _Row_base<_Tp, _Number2> _Base;
54    typedef _Number2 pencil_type;
55  public:
56    explicit row(const pencil_type& __a = pencil_type()) : _Base(__a) {}
57  };
58}
59
60void test2_b() {
61  TestTemp::row<const char*> x; // no-warning
62}
63
64//===----------------------------------------------------------------------===//
65// Test references.
66//===----------------------------------------------------------------------===//
67
68void test3_a(int x) {
69   x = x + 1; // expected-warning{{never read}}
70}
71
72void test3_b(int &x) {
73  x = x + 1; // no-warninge
74}
75
76void test3_c(int x) {
77  int &y = x;
78  // Shows the limitation of dead stores tracking.  The write is really
79  // dead since the value cannot escape the function.
80  ++y; // no-warning
81}
82
83void test3_d(int &x) {
84  int &y = x;
85  ++y; // no-warning
86}
87
88void test3_e(int &x) {
89  int &y = x;
90}
91
92//===----------------------------------------------------------------------===//
93// Dead stores involving 'new'
94//===----------------------------------------------------------------------===//
95
96static void test_new(unsigned n) {
97  char **p = new char* [n]; // expected-warning{{never read}}
98}
99
100//===----------------------------------------------------------------------===//
101// Dead stores in namespaces.
102//===----------------------------------------------------------------------===//
103
104namespace foo {
105  int test_4(int x) {
106    x = 2; // expected-warning{{Value stored to 'x' is never read}}
107    x = 2;
108    return x;
109  }
110}
111
112//===----------------------------------------------------------------------===//
113// Dead stores in with EH code.
114//===----------------------------------------------------------------------===//
115
116void test_5_Aux();
117int test_5() {
118  int x = 0;
119  try {
120    x = 2; // no-warning
121    test_5_Aux();
122  }
123  catch (int z) {
124    return x + z;
125  }
126  return 1;
127}
128
129