clang/test/SemaCXX/constexpr-duffs-device.cpp

   1 // RUN: %clang_cc1 -std=c++1y -verify %s
   2
   3 // expected-no-diagnostics
   4 constexpr void copy(const char *from, unsigned long count, char *to) {
   5         unsigned long n = (count + 7) / 8;
   6         switch(count % 8) {
   7         case 0: do {    *to++ = *from++;
   8         case 7:         *to++ = *from++;
   9         case 6:         *to++ = *from++;
  10         case 5:         *to++ = *from++;
  11         case 4:         *to++ = *from++;
  12         case 3:         *to++ = *from++;
  13         case 2:         *to++ = *from++;
  14         case 1:         *to++ = *from++;
  15                 } while(--n > 0);
  16         }
  17 }
  18
  19 struct S {
  20   char stuff[14];
  21   constexpr S() : stuff{} {
  22     copy("Hello, world!", 14, stuff);
  23   }
  24 };
  25
  26 constexpr bool streq(const char *a, const char *b) {
  27   while (*a && *a == *b) ++a, ++b;
  28   return *a == *b;
  29 }
  30
  31 static_assert(streq(S().stuff, "Hello, world!"), "should be same");
  32 static_assert(!streq(S().stuff, "Something else"), "should be different");