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

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