reference.cpp revision 5699f62df144545702b91e91836a63db4e5f2627 
1// RUN: %clang_cc1 -analyze -analyzer-checker=core,alpha.core,debug.ExprInspection -analyzer-store=region -analyzer-constraints=range -verify -Wno-null-dereference %s
2
3void clang_analyzer_eval(bool);
4
5typedef typeof(sizeof(int)) size_t;
6void malloc (size_t);
7
8void f1() {
9  int const &i = 3;
10  int b = i;
11
12  int *p = 0;
13
14  if (b != 3)
15    *p = 1; // no-warning
16}
17
18char* ptr();
19char& ref();
20
21// These next two tests just shouldn't crash.
22char t1 () {
23  ref() = 'c';
24  return '0';
25}
26
27// just a sanity test, the same behavior as t1()
28char t2 () {
29  *ptr() = 'c';
30  return '0';
31}
32
33// Each of the tests below is repeated with pointers as well as references.
34// This is mostly a sanity check, but then again, both should work!
35char t3 () {
36  char& r = ref();
37  r = 'c'; // no-warning
38  if (r) return r;
39  return *(char*)0; // no-warning
40}
41
42char t4 () {
43  char* p = ptr();
44  *p = 'c'; // no-warning
45  if (*p) return *p;
46  return *(char*)0; // no-warning
47}
48
49char t5 (char& r) {
50  r = 'c'; // no-warning
51  if (r) return r;
52  return *(char*)0; // no-warning
53}
54
55char t6 (char* p) {
56  *p = 'c'; // no-warning
57  if (*p) return *p;
58  return *(char*)0; // no-warning
59}
60
61
62// PR13440 / <rdar://problem/11977113>
63// Test that the array-to-pointer decay works for array references as well.
64// More generally, when we want an lvalue for a reference field, we still need
65// to do one level of load.
66namespace PR13440 {
67  typedef int T[1];
68  struct S {
69    T &x;
70
71    int *m() { return x; }
72  };
73
74  struct S2 {
75    int (&x)[1];
76
77    int *m() { return x; }
78  };
79
80  void test() {
81    int a[1];
82    S s = { a };
83    S2 s2 = { a };
84
85    if (s.x != a) return;
86    if (s2.x != a) return;
87
88    a[0] = 42;
89    clang_analyzer_eval(s.x[0] == 42); // expected-warning{{TRUE}}
90    clang_analyzer_eval(s2.x[0] == 42); // expected-warning{{TRUE}}
91  }
92}
93
94void testNullReference() {
95  int *x = 0;
96  int &y = *x; // expected-warning{{Dereference of null pointer}}
97  y = 5;
98}
99
100void testRetroactiveNullReference(int *x) {
101  // According to the C++ standard, there is no such thing as a
102  // "null reference". So the 'if' statement ought to be dead code.
103  // However, Clang (and other compilers) don't actually check that a pointer
104  // value is non-null in the implementation of references, so it is possible
105  // to produce a supposed "null reference" at runtime. The analyzer shoeuld
106  // still warn when it can prove such errors.
107  int &y = *x;
108  if (x != 0)
109    return;
110  y = 5; // expected-warning{{Dereference of null pointer}}
111}
112
113void testReferenceAddress(int &x) {
114  clang_analyzer_eval(&x != 0); // expected-warning{{TRUE}}
115  clang_analyzer_eval(&ref() != 0); // expected-warning{{TRUE}}
116
117  struct S { int &x; };
118
119  extern S *getS();
120  clang_analyzer_eval(&getS()->x != 0); // expected-warning{{TRUE}}
121}
122
123
124void testFunctionPointerReturn(void *opaque) {
125  typedef int &(*RefFn)();
126
127  RefFn getRef = (RefFn)opaque;
128
129  // Don't crash writing to or reading from this reference.
130  int &x = getRef();
131  x = 42;
132  clang_analyzer_eval(x == 42); // expected-warning{{TRUE}}
133}
134
135
136// ------------------------------------
137// False negatives
138// ------------------------------------
139
140namespace rdar11212286 {
141  class B{};
142
143  B test() {
144    B *x = 0;
145    return *x; // should warn here!
146  }
147
148  B &testRef() {
149    B *x = 0;
150    return *x; // should warn here!
151  }
152}
153
154void testReferenceFieldAddress() {
155  struct S { int &x; };
156
157  extern S getS();
158  clang_analyzer_eval(&getS().x != 0); // expected-warning{{UNKNOWN}}
159}
160