clang/test/SemaCXX/warn-tautological-undefined-compare.cpp

   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
   6 void 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
  14 class 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
  36 namespace 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
 114 namespace macros {
 115   #define assert(x) if (x) {}
 116
 117   void test(int &x) {
 118     assert(&x != 0);
 119     // 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}}
 120     assert(&x == 0);
 121     // 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}}
 122     assert(&x != 0 && "Expecting valid reference");
 123     // 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}}
 124     assert(&x == 0 && "Expecting invalid reference");
 125     // 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}}
 126   }
 127
 128   class S {
 129     void test() {
 130       assert(this != 0);
 131       // expected-warning@-1{{'this' pointer cannot be null in well-defined C++ code; comparison may be assumed to always evaluate to true}}
 132       assert(this == 0);
 133       // expected-warning@-1{{'this' pointer cannot be null in well-defined C++ code; comparison may be assumed to always evaluate to false}}
 134       assert(this != 0 && "Expecting valid reference");
 135       // expected-warning@-1{{'this' pointer cannot be null in well-defined C++ code; comparison may be assumed to always evaluate to true}}
 136       assert(this == 0 && "Expecting invalid reference");
 137       // expected-warning@-1{{'this' pointer cannot be null in well-defined C++ code; comparison may be assumed to always evaluate to false}}
 138     }
 139   };
 140 }