warn-tautological-undefined-compare.cpp revision c568f1e98938584c0ef0b12ae5018ff7d90a4072 
1// RUN: %clang_cc1 -fsyntax-only -verify %s
2// RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-undefined-compare %s
3// RUN: %clang_cc1 -fsyntax-only -verify -Wno-tautological-compare -Wtautological-undefined-compare %s
4// RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-compare %s
5
6void test1(int &x) {
7  if (x == 1) { }
8  if (&x == 0) { }
9  // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
10  if (&x != 0) { }
11  // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
12}
13
14class test2 {
15  test2() : x(y) {}
16
17  void foo() {
18    if (this == 0) { }
19    // expected-warning@-1{{'this' pointer cannot be null in well-defined C++ code; comparison may be assumed to always evaluate to false}}
20    if (this != 0) { }
21    // expected-warning@-1{{'this' pointer cannot be null in well-defined C++ code; comparison may be assumed to always evaluate to true}}
22  }
23
24  void bar() {
25    if (x == 1) { }
26    if (&x == 0) { }
27    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
28    if (&x != 0) { }
29    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
30  }
31
32  int &x;
33  int y;
34};
35
36namespace function_return_reference {
37  int& get_int();
38  // expected-note@-1 4{{'get_int' returns a reference}}
39  class B {
40  public:
41    static int &stat();
42    // expected-note@-1 4{{'stat' returns a reference}}
43    int &get();
44    // expected-note@-1 8{{'get' returns a reference}}
45  };
46
47  void test() {
48    if (&get_int() == 0) {}
49    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
50    if (&(get_int()) == 0) {}
51    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
52
53    if (&get_int() != 0) {}
54    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
55    if (&(get_int()) != 0) {}
56    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
57
58    if (&B::stat() == 0) {}
59    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
60    if (&(B::stat()) == 0) {}
61    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
62
63    if (&B::stat() != 0) {}
64    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
65    if (&(B::stat()) != 0) {}
66    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
67
68    B b;
69    if (&b.get() == 0) {}
70    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
71    if (&(b.get()) == 0) {}
72    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
73
74    if (&b.get() != 0) {}
75    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
76    if (&(b.get()) != 0) {}
77    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
78
79    B* b_ptr = &b;
80    if (&b_ptr->get() == 0) {}
81    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
82    if (&(b_ptr->get()) == 0) {}
83    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
84
85    if (&b_ptr->get() != 0) {}
86    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
87    if (&(b_ptr->get()) != 0) {}
88    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
89
90    int& (B::*m_ptr)() = &B::get;
91    if (&(b.*m_ptr)() == 0) {}
92    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
93    if (&((b.*m_ptr)()) == 0) {}
94    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
95
96    if (&(b.*m_ptr)() != 0) {}
97    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
98    if (&((b.*m_ptr)()) != 0) {}
99    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
100
101    int& (*f_ptr)() = &get_int;
102    if (&(*f_ptr)() == 0) {}
103    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
104    if (&((*f_ptr)()) == 0) {}
105    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false}}
106
107    if (&(*f_ptr)() != 0) {}
108    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
109    if (&((*f_ptr)()) != 0) {}
110    // expected-warning@-1{{reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to true}}
111  }
112}
113