clang/test/AST/ByteCode/switch.cpp

   1 // RUN: %clang_cc1 -std=c++17 -fexperimental-new-constant-interpreter -verify=expected,both %s
   2 // RUN: %clang_cc1 -std=c++17 -verify=ref,both %s
   3
   4 constexpr bool isEven(int a) {
   5   bool v = false;
   6   switch(a) {
   7   case 2: return true;
   8   case 4: return true;
   9   case 6: return true;
  10
  11   case 8:
  12   case 10:
  13   case 12:
  14   case 14:
  15   case 16:
  16     return true;
  17   case 18:
  18     v = true;
  19     break;
  20
  21   default:
  22   switch(a) {
  23   case 1:
  24     break;
  25   case 3:
  26     return false;
  27   default:
  28     break;
  29   }
  30   }
  31
  32   return v;
  33 }
  34 static_assert(isEven(2), "");
  35 static_assert(isEven(8), "");
  36 static_assert(isEven(10), "");
  37 static_assert(isEven(18), "");
  38 static_assert(!isEven(1), "");
  39 static_assert(!isEven(3), "");
  40
  41
  42 constexpr int withInit() {
  43   switch(int a = 2; a) {
  44     case 1: return -1;
  45     case 2: return 2;
  46   }
  47   return -1;
  48 }
  49 static_assert(withInit() == 2, "");
  50
  51 constexpr int FT(int a) {
  52   int m = 0;
  53   switch(a) {
  54   case 4: m++;
  55   case 3: m++;
  56   case 2: m++;
  57   case 1: m++;
  58     return m;
  59   }
  60
  61   return -1;
  62 }
  63 static_assert(FT(1) == 1, "");
  64 static_assert(FT(4) == 4, "");
  65 static_assert(FT(5) == -1, "");
  66
  67
  68 constexpr int good() { return 1; }
  69 constexpr int test(int val) {
  70   switch (val) {
  71   case good(): return 100;
  72   default: return -1;
  73   }
  74   return 0;
  75 }
  76 static_assert(test(1) == 100, "");
  77
  78 constexpr int bad(int val) { return val / 0; } // both-warning {{division by zero}}
  79 constexpr int another_test(int val) { // both-note {{declared here}}
  80   switch (val) {
  81   case bad(val): return 100; // both-error {{case value is not a constant expression}} \
  82                              // both-note {{cannot be used in a constant expression}}
  83   default: return -1;
  84   }
  85   return 0;
  86 }
  87 static_assert(another_test(1) == 100, ""); // both-error {{static assertion failed}} \
  88                                            // both-note {{evaluates to}}