clang/test/CXX/temp/temp.constr/temp.constr.order/class-template-partial-specializations.cpp

   1 // RUN: %clang_cc1 -std=c++2a -x c++ -verify %s
   2
   3 template<typename T> requires (sizeof(T) >= 4)
   4 // expected-note@-1{{similar constraint expressions not considered equivalen}}
   5 class A{}; // expected-note{{template is declared here}}
   6
   7 template<typename T> requires (sizeof(T) >= 4 && sizeof(T) <= 10)
   8 // expected-note@-1{{similar constraint expression here}}
   9
  10 class A<T>{}; // expected-error{{class template partial specialization is not more specialized than the primary template}}
  11
  12 template<typename T>
  13 concept C1 = sizeof(T) >= 4;
  14
  15 template<typename T> requires C1<T>
  16 class B{};
  17
  18 template<typename T> requires (C1<T> && sizeof(T) <= 10)
  19 class B<T>{};
  20
  21 template<typename T>
  22 concept C2 = sizeof(T) > 1 && sizeof(T) <= 8;
  23
  24 template<typename T>
  25 class C{};
  26
  27 template<typename T> requires C1<T>
  28 class C<T>{};
  29
  30 template<typename T>
  31 class D{}; // expected-note{{previous definition is here}}
  32
  33 template<typename T>
  34 class D<T>{}; // expected-error{{class template partial specialization does not specialize any template argument; to define the primary template, remove the template argument list}} expected-error{{redefinition of 'D'}}
  35
  36 template<typename T> requires C1<T> // expected-note{{previous template declaration is here}}
  37 class E{};
  38
  39 template<typename T> // expected-error{{requires clause differs in template redeclaration}}
  40 class E<T>{}; // expected-error{{class template partial specialization does not specialize any template argument; to define the primary template, remove the template argument list}}
  41
  42 template<typename T>
  43 struct F{ enum{ value = 1 }; };
  44
  45 template<typename T> requires C1<T> && C2<T>
  46 struct F<T>{ enum{ value = 2 }; };
  47
  48 template<typename T> requires C1<T> || C2<T>
  49 struct F<T>{ enum{ value = 3 }; };
  50
  51 static_assert(F<unsigned>::value == 2);
  52 static_assert(F<char[10]>::value == 3);
  53 static_assert(F<char>::value == 1);
  54
  55 template <unsigned I>
  56 struct S {
  57   template <typename T>
  58   struct F {
  59     enum { value = 1 };
  60   };
  61
  62   template <typename T>
  63     requires C1<T> && C2<T>
  64   struct F<T> {
  65     enum { value = 2 };
  66   };
  67
  68   template <typename T>
  69     requires C1<T> || C2<T>
  70   struct F<T> {
  71     enum { value = 3 };
  72   };
  73 };
  74
  75 static_assert(S<1>::F<unsigned>::value == 2);
  76 static_assert(S<1>::F<char[10]>::value == 3);
  77 static_assert(S<1>::F<char>::value == 1);
  78
  79 // Make sure atomic constraints subsume each other only if their parameter
  80 // mappings are identical.
  81
  82 template<typename T, typename U> requires C2<T>
  83 struct I { }; // expected-note {{template is declared here}}
  84
  85 template<typename T, typename U> requires C2<U>
  86 struct I<T, U> { }; // expected-error {{class template partial specialization is not more specialized than the primary template}}
  87
  88 template<typename T, typename U> requires C2<T> && C2<U>
  89 struct I<T, U> { };