clang/test/SemaCXX/tautological-negation-compare.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-negation-compare -Wno-constant-logical-operand %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-compare -Wno-constant-logical-operand %s
   3 // RUN: %clang_cc1 -fsyntax-only -verify -Wall -Wno-unused -Wno-loop-analysis -Wno-constant-logical-operand %s
   4
   5 #define COPY(x) x
   6
   7 void test_int(int x) {
   8   if (x || !x) {} // expected-warning {{'||' of a value and its negation always evaluates to true}}
   9   if (!x || x) {} // expected-warning {{'||' of a value and its negation always evaluates to true}}
  10   if (x && !x) {} // expected-warning {{'&&' of a value and its negation always evaluates to false}}
  11   if (!x && x) {} // expected-warning {{'&&' of a value and its negation always evaluates to false}}
  12
  13   // parentheses are ignored
  14   if (x || (!x)) {} // expected-warning {{'||' of a value and its negation always evaluates to true}}
  15   if (!(x) || x) {} // expected-warning {{'||' of a value and its negation always evaluates to true}}
  16
  17   // don't warn on macros
  18   if (COPY(x) || !x) {}
  19   if (!x || COPY(x)) {}
  20   if (x && COPY(!x)) {}
  21   if (COPY(!x && x)) {}
  22
  23   // dont' warn on literals
  24   if (1 || !1) {}
  25   if (!42 && 42) {}
  26
  27
  28   // don't warn on overloads
  29   struct Foo{
  30     int val;
  31     Foo operator!() const { return Foo{!val}; }
  32     bool operator||(const Foo other) const { return val || other.val; }
  33     bool operator&&(const Foo other) const { return val && other.val; }
  34   };
  35
  36   Foo f{3};
  37   if (f || !f) {}
  38   if (!f || f) {}
  39   if (f.val || !f.val) {} // expected-warning {{'||' of a value and its negation always evaluates to true}}
  40   if (!f.val && f.val) {} // expected-warning {{'&&' of a value and its negation always evaluates to false}}
  41 }