clang/test/SemaCXX/warn-bitwise-compare.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-bitwise-compare %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -Wall -Wno-unused %s
   3
   4 void test(int x) {
   5   bool b1 = (8 & x) == 3;
   6   // expected-warning@-1 {{bitwise comparison always evaluates to false}}
   7   bool b2 = x | 5;
   8   // expected-warning@-1 {{bitwise or with non-zero value always evaluates to true}}
   9   bool b3 = (x | 5);
  10   // expected-warning@-1 {{bitwise or with non-zero value always evaluates to true}}
  11   bool b4 = !!(x | 5);
  12   // expected-warning@-1 {{bitwise or with non-zero value always evaluates to true}}
  13 }
  14
  15 template <int I, class T>  // silence
  16 void foo(int x) {
  17     bool b1 = (x & sizeof(T)) == 8;
  18     bool b2 = (x & I) == 8;
  19     bool b3 = (x & 4) == 8; // expected-warning {{bitwise comparison always evaluates to false}}
  20 }
  21
  22 void run(int x) {
  23     foo<4, int>(8); // expected-note {{in instantiation of function template specialization 'foo<4, int>' requested here}}
  24 }