clang/test/SemaCXX/warn-assignment-condition.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -Wparentheses -verify %s
   2
   3 struct A {
   4   int foo();
   5   friend A operator+(const A&, const A&);
   6   A operator|=(const A&);
   7   operator bool();
   8 };
   9
  10 void test() {
  11   int x, *p;
  12   A a, b;
  13
  14   // With scalars.
  15   if (x = 7) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  16                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  17   // expected-note{{place parentheses around the assignment to silence this warning}}
  18   if ((x = 7)) {}
  19   do {
  20   } while (x = 7); // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  21                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  22   // expected-note{{place parentheses around the assignment to silence this warning}}
  23   do {
  24   } while ((x = 7));
  25   while (x = 7) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  26                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  27   // expected-note{{place parentheses around the assignment to silence this warning}}
  28
  29   while ((x = 7)) {}
  30   for (; x = 7; ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  31                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  32   // expected-note{{place parentheses around the assignment to silence this warning}}
  33   for (; (x = 7); ) {}
  34
  35   if (p = p) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  36                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  37   // expected-note{{place parentheses around the assignment to silence this warning}}
  38   if ((p = p)) {}
  39   do {
  40   } while (p = p); // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  41                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  42   // expected-note{{place parentheses around the assignment to silence this warning}}
  43   do {
  44   } while ((p = p));
  45   while (p = p) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  46                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  47   // expected-note{{place parentheses around the assignment to silence this warning}}
  48   while ((p = p)) {}
  49   for (; p = p; ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  50                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  51   // expected-note{{place parentheses around the assignment to silence this warning}}
  52   for (; (p = p); ) {}
  53
  54   // Initializing variables (shouldn't warn).
  55   if (int y = x) {}
  56   while (int y = x) {}
  57   if (A y = a) {}
  58   while (A y = a) {}
  59
  60   // With temporaries.
  61   if (x = (b+b).foo()) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  62                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  63   // expected-note{{place parentheses around the assignment to silence this warning}}
  64   if ((x = (b+b).foo())) {}
  65   do {
  66   } while (x = (b+b).foo()); // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  67                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  68   // expected-note{{place parentheses around the assignment to silence this warning}}
  69   do {
  70   } while ((x = (b+b).foo()));
  71   while (x = (b+b).foo()) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  72                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  73   // expected-note{{place parentheses around the assignment to silence this warning}}
  74   while ((x = (b+b).foo())) {}
  75   for (; x = (b+b).foo(); ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  76                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  77   // expected-note{{place parentheses around the assignment to silence this warning}}
  78   for (; (x = (b+b).foo()); ) {}
  79
  80   // With a user-defined operator.
  81   if (a = b + b) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  82                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  83   // expected-note{{place parentheses around the assignment to silence this warning}}
  84   if ((a = b + b)) {}
  85   do {
  86   } while (a = b + b); // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  87                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  88   // expected-note{{place parentheses around the assignment to silence this warning}}
  89   do {
  90   } while ((a = b + b));
  91   while (a = b + b) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  92                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  93   // expected-note{{place parentheses around the assignment to silence this warning}}
  94   while ((a = b + b)) {}
  95   for (; a = b + b; ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
  96                 // expected-note{{use '==' to turn this assignment into an equality comparison}} \
  97   // expected-note{{place parentheses around the assignment to silence this warning}}
  98   for (; (a = b + b); ) {}
  99
 100   // Compound assignments.
 101   if (x |= 2) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
 102                 // expected-note{{use '!=' to turn this compound assignment into an inequality comparison}} \
 103   // expected-note{{place parentheses around the assignment to silence this warning}}
 104
 105   if (a |= b) {} // expected-warning {{using the result of an assignment as a condition without parentheses}} \
 106                 // expected-note{{use '!=' to turn this compound assignment into an inequality comparison}} \
 107   // expected-note{{place parentheses around the assignment to silence this warning}}
 108
 109   if ((x == 5)) {} // expected-warning {{equality comparison with extraneous parentheses}} \
 110                    // expected-note {{use '=' to turn this equality comparison into an assignment}} \
 111                    // expected-note {{remove extraneous parentheses around the comparison to silence this warning}}
 112
 113 #pragma clang diagnostic push
 114 #pragma clang diagnostic ignored "-Wparentheses-equality"
 115   if ((x == 5)) {} // no-warning
 116 #pragma clang diagnostic pop
 117
 118   if ((5 == x)) {}
 119
 120 #define EQ(x,y) ((x) == (y))
 121   if (EQ(x, 5)) {}
 122 #undef EQ
 123 }
 124
 125 void (*fn)();
 126
 127 void test2() {
 128     if ((fn == test2)) {} // expected-warning {{equality comparison with extraneous parentheses}} \
 129                           // expected-note {{use '=' to turn this equality comparison into an assignment}} \
 130                           // expected-note {{remove extraneous parentheses around the comparison to silence this warning}}
 131     if ((test2 == fn)) {}
 132 }
 133
 134 namespace rdar9027658 {
 135 template <typename T>
 136 void f(T t) {
 137     if ((t.g == 3)) { } // expected-warning {{equality comparison with extraneous parentheses}} \
 138                          // expected-note {{use '=' to turn this equality comparison into an assignment}} \
 139                          // expected-note {{remove extraneous parentheses around the comparison to silence this warning}}
 140 }
 141
 142 struct S { int g; };
 143 void test() {
 144   f(S()); // expected-note {{in instantiation}}
 145 }
 146 }