clang/test/SemaCXX/deduced-return-void.cpp

   1 // RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify %s
   2 // RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
   3
   4 // Check that we don't get any extra warning for "return" without an
   5 // expression, in a function that might have been intended to return
   6 // void all along.
   7 decltype(h1) h1() { // expected-error {{use of undeclared identifier 'h1'}}
   8   return;
   9 }
  10
  11 namespace JustAuto {
  12 int i;
  13 auto f1() { }
  14 auto f2() { return; }
  15 auto f3() { return void(); }
  16 auto f4() {
  17   return i;
  18   return; // expected-error {{'auto' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
  19 }
  20 auto f5() {
  21   return i;
  22   return void(); // expected-error {{'auto' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
  23 }
  24
  25 auto l1 = []() { };
  26 auto l2 = []() { return; };
  27 auto l3 = []() { return void(); };
  28 auto l4 = []() {
  29   return i;
  30   return; // expected-error {{return type 'void' must match previous return type 'int' when lambda expression has unspecified explicit return type}}
  31 };
  32 auto l5 = []() {
  33   return i;
  34   return void(); // expected-error {{return type 'void' must match previous return type 'int' when lambda expression has unspecified explicit return type}}
  35 };
  36
  37 } // namespace JustAuto
  38
  39 namespace DecltypeAuto {
  40 int i;
  41 decltype(auto) f1() { }
  42 decltype(auto) f2() { return; }
  43 decltype(auto) f3() { return void(); }
  44 decltype(auto) f4() {
  45   return i;
  46   return; // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
  47 }
  48 decltype(auto) f5() {
  49   return i;
  50   return void(); // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
  51 }
  52
  53 auto l1 = []() -> decltype(auto) { };
  54 auto l2 = []() -> decltype(auto) { return; };
  55 auto l3 = []() -> decltype(auto) { return void(); };
  56 auto l4 = []() -> decltype(auto) {
  57   return i;
  58   return; // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
  59 };
  60 auto l5 = []() -> decltype(auto) {
  61   return i;
  62   return void(); // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
  63 };
  64
  65 } // namespace DecltypeAuto
  66
  67 namespace AutoPtr {
  68 int i;
  69 auto *f1() { } // expected-error {{cannot deduce return type 'auto *' for function with no return statements}}
  70 auto *f2() {
  71   return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
  72 }
  73 auto *f3() {
  74   return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
  75 }
  76 auto *f4() {
  77   return &i;
  78   return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
  79 }
  80 auto *f5() {
  81   return &i;
  82   return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
  83 }
  84
  85 auto l1 = []() -> auto* { }; // expected-error {{cannot deduce return type 'auto *' for function with no return statements}}
  86 auto l2 = []() -> auto* {
  87   return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
  88 };
  89 auto l3 = []() -> auto* {
  90   return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
  91 };
  92 auto l4 = []() -> auto* {
  93   return &i;
  94   return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
  95 };
  96 auto l5 = []() -> auto* {
  97   return &i;
  98   return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
  99 };
 100 } // namespace AutoPtr
 101
 102 namespace AutoRef {
 103 int i;
 104 auto& f1() { // expected-error {{cannot deduce return type 'auto &' for function with no return statements}}
 105 }
 106 auto& f2() {
 107   return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
 108 }
 109 auto& f3() {
 110   return void(); // expected-error@-1 {{cannot form a reference to 'void'}}
 111 }
 112 auto& f4() {
 113   return i;
 114   return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
 115 }
 116 auto& f5() {
 117   return i;
 118   return void(); // expected-error {{deduced as 'int' in earlier return statement}}
 119 }
 120 auto& f6() { return 42; } // expected-error {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
 121
 122 auto l1 = []() -> auto& { }; // expected-error {{cannot deduce return type 'auto &' for function with no return statements}}
 123 auto l2 = []() -> auto& {
 124   return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
 125 };
 126 auto l3 = []() -> auto& { // expected-error {{cannot form a reference to 'void'}}
 127   return void();
 128 };
 129 auto l4 = []() -> auto& {
 130   return i;
 131   return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
 132 };
 133 auto l5 = []() -> auto & {
 134   return i;
 135   return void(); // expected-error {{deduced as 'int' in earlier return statement}}
 136 };
 137 auto l6 = []() -> auto& {
 138   return 42; // expected-error {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
 139 };
 140 } // namespace AutoRef