clang/test/CXX/stmt.stmt/stmt.select/stmt.if/p4.cpp

   1 // RUN: %clang_cc1 -std=c++23 -verify %s
   2
   3 void test_consteval() {
   4   if consteval ({(void)1;});  // expected-error {{expected { after consteval}}
   5   if consteval (void) 0; // expected-error {{expected { after consteval}}
   6   if consteval {
   7     (void)0;
   8   } else (void)0; // expected-error {{expected { after else}}
   9
  10   static_assert([] {
  11     if consteval {
  12       return 0;
  13     }
  14     return 1;
  15   }() == 0);
  16
  17   static_assert([] {
  18     if consteval {
  19       return 0;
  20     } else {
  21       return 1;
  22     }
  23   }() == 0);
  24
  25   static_assert([] {
  26     if !consteval {
  27       return 0;
  28     } else {
  29       return 1;
  30     }
  31   }() == 1);
  32
  33   static_assert([] {
  34     if not consteval {
  35       return 0;
  36     }
  37     return 1;
  38   }() == 1);
  39
  40   if consteval [[likely]] { // expected-warning {{attribute 'likely' has no effect when annotating an 'if consteval' statement}}\
  41                             // expected-note 2{{annotating the 'if consteval' statement here}}
  42
  43
  44   }
  45   else [[unlikely]] { // expected-warning {{attribute 'unlikely' has no effect when annotating an 'if consteval' statement}}
  46
  47   }
  48
  49 }
  50
  51 void test_consteval_jumps() {
  52   if consteval { // expected-note 4{{jump enters controlled statement of consteval if}}
  53     goto a;
  54     goto b; // expected-error {{cannot jump from this goto statement to its label}}
  55   a:;
  56   } else {
  57     goto b;
  58     goto a; // expected-error {{cannot jump from this goto statement to its label}}
  59   b:;
  60   }
  61   goto a; // expected-error {{cannot jump from this goto statement to its label}}
  62   goto b; // expected-error {{cannot jump from this goto statement to its label}}
  63 }
  64
  65 void test_consteval_switch() {
  66   int x = 42;
  67   switch (x) {
  68     if consteval { // expected-note 2{{jump enters controlled statement of consteval if}}
  69     case 1:;       // expected-error {{cannot jump from switch statement to this case label}}
  70     default:;      // expected-error {{cannot jump from switch statement to this case label}}
  71     } else {
  72     }
  73   }
  74   switch (x) {
  75     if consteval { // expected-note 2{{jump enters controlled statement of consteval if}}
  76     } else {
  77     case 2:;  // expected-error {{cannot jump from switch statement to this case label}}
  78     default:; // expected-error {{cannot jump from switch statement to this case label}}
  79     }
  80   }
  81 }
  82
  83 consteval int f(int i) { return i; }
  84 constexpr int g(int i) {
  85   if consteval {
  86     return f(i);
  87   } else {
  88     return 42;
  89   }
  90 }
  91 static_assert(g(10) == 10);
  92
  93 constexpr int h(int i) { // expected-note {{declared here}}
  94   if !consteval {
  95     return f(i); // expected-error {{call to consteval function 'f' is not a constant expression}}\
  96                      // expected-note  {{cannot be used in a constant expression}}
  97   }
  98   return 0;
  99 }
 100
 101 consteval void warn_in_consteval() {
 102   if consteval { // expected-warning {{consteval if is always true in an immediate context}}
 103     if consteval {} // expected-warning {{consteval if is always true in an immediate context}}
 104   }
 105 }
 106
 107 constexpr void warn_in_consteval2() {
 108   if consteval {
 109     if consteval {} // expected-warning {{consteval if is always true in an immediate context}}
 110   }
 111 }
 112
 113 auto y = []() consteval {
 114   if consteval { // expected-warning {{consteval if is always true in an immediate context}}
 115     if consteval {} // expected-warning {{consteval if is always true in an immediate context}}
 116   }
 117 };
 118
 119 namespace test_transform {
 120 int f(auto n) {
 121   if consteval {
 122     n.foo; //expected-error {{no member named}}
 123   }
 124   else {
 125   }
 126
 127   if !consteval {
 128     n.foo; //expected-error {{no member named}}
 129   }
 130   else {
 131   }
 132
 133   return 0;
 134 }
 135
 136 constexpr int g(auto n) {
 137   if consteval {
 138   }
 139   else {
 140     n.foo; //expected-error {{no member named}}
 141   }
 142
 143   if !consteval {
 144   }
 145   else {
 146      n.foo; //expected-error {{no member named}}
 147   }
 148
 149   return 0;
 150 }
 151
 152 struct S {};
 153 void test() {
 154   f(S{}); //expected-note {{in instantiation}}
 155   g(S{}); //expected-note {{in instantiation}}
 156 }
 157
 158 }