reference.cpp revision 02df4f0aef142f00d4637cd851e54da2a123ca8e 
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  extern S *getSP();
123  clang_analyzer_eval(&getSP()->x != 0); // expected-warning{{TRUE}}
124}
125
126
127void testFunctionPointerReturn(void *opaque) {
128  typedef int &(*RefFn)();
129
130  RefFn getRef = (RefFn)opaque;
131
132  // Don't crash writing to or reading from this reference.
133  int &x = getRef();
134  x = 42;
135  clang_analyzer_eval(x == 42); // expected-warning{{TRUE}}
136}
137
138
139// ------------------------------------
140// False negatives
141// ------------------------------------
142
143namespace rdar11212286 {
144  class B{};
145
146  B test() {
147    B *x = 0;
148    return *x; // should warn here!
149  }
150
151  B &testRef() {
152    B *x = 0;
153    return *x; // should warn here!
154  }
155}
156