clang/test/CXX/dcl/dcl.decl/p3.cpp

   1 // RUN:  %clang_cc1 -std=c++2a -verify %s
   2
   3 template<typename T, typename U>
   4 constexpr bool is_same_v = false;
   5
   6 template<typename T>
   7 constexpr bool is_same_v<T, T> = true;
   8
   9 using T = void ();
  10
  11 void f1non_templ(int a) requires true; // expected-error{{non-templated function cannot have a requires clause}}
  12 auto f2non_templ(int a) -> bool requires true; // expected-error{{non-templated function cannot have a requires clause}}
  13 auto f3non_templ(int a) -> bool (*)(int b) requires true; // expected-error{{non-templated function cannot have a requires clause}}
  14 // expected-error@+1{{non-templated function cannot have a requires clause}}
  15 auto f4_non_templ(int a) requires true -> bool; // expected-error{{trailing return type must appear before trailing requires clause}}
  16 void (f7non_templ()) requires true; // expected-error{{non-templated function cannot have a requires clause}}
  17 // expected-error@+1{{non-templated function cannot have a requires clause}}
  18 void (f8non_templ() requires true); // expected-error{{trailing requires clause should be placed outside parentheses}}
  19 // expected-error@+1{{non-templated function cannot have a requires clause}}
  20 T xnon_templ requires true;
  21 // expected-error@+2 2{{non-templated function cannot have a requires clause}}
  22 struct Snon_templ {
  23   T m1 requires true, m2 requires true;
  24 };
  25
  26 template <typename>
  27 void f1(int a)
  28   requires true;                               // OK
  29
  30 template <typename>
  31 auto f2(int a) -> bool
  32   requires true;                                 // OK
  33
  34 template <typename>
  35 auto f3(int a) -> bool (*)(int b) requires true; // OK
  36 template <typename>
  37 auto f4(int a) requires true -> bool; // expected-error{{trailing return type must appear before trailing requires clause}}
  38 int f5(int a) requires; // expected-error{{expected expression}}
  39 int f6(int a) requires {} // expected-error{{expected expression}}
  40 template<typename>
  41 void (f7()) requires true;
  42 template<typename>
  43 void (f8() requires true); // expected-error{{trailing requires clause should be placed outside parentheses}}
  44 void (*(f9 requires (true)))(); // expected-error{{trailing requires clause should be placed outside parentheses}}
  45 static_assert(is_same_v<decltype(f9), void (*)()>);
  46 void (*pf)() requires true; // expected-error{{trailing requires clause can only be used when declaring a function}}
  47 void g1(int (*dsdads)() requires false); // expected-error{{trailing requires clause can only be used when declaring a function}}
  48 void g2(int (*(*dsdads)())() requires true); // expected-error{{trailing requires clause can only be used when declaring a function}}
  49 void g3(int (*(*dsdads)(int) requires true)() ); // expected-error{{trailing requires clause should be placed outside parentheses}}
  50
  51 template<typename U>
  52 struct Foo{
  53 T x requires true;
  54 };
  55 Foo<int> f;
  56
  57 template<typename>
  58 struct S {
  59   T m1 requires true, m2 requires true;
  60 };
  61
  62 template<typename T>
  63 struct R {
  64     R(T t);
  65 };
  66
  67 template<typename T>
  68 R(T) -> R<T> requires true; // expected-error{{deduction guide cannot have a requires clause}}