llvm-project/clang/test/SemaTemplate/class-template-decl.cpp

// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify %s

template<typename T> class A {};

extern "C++" {
  template<typename T> class B {};
  template<typename T> class A<T *>;
  template<> class A<int[1]>;
  template class A<int[2]>;
  template<typename T> class B<T *>;
  template<> class B<int[1]>;
  template class B<int[2]>;
}

namespace N {
  template<typename T> class C;
}

extern "C" { // expected-note 3 {{extern "C" language linkage specification begins here}}
  template<typename T> class D; // expected-error{{templates must have C++ linkage}}
  template<typename T> class A<T **>; // expected-error{{templates must have C++ linkage}}
  template<> class A<int[3]>; // expected-error{{templates must have C++ linkage}}
  template class A<int[4]>; // OK (surprisingly) FIXME: Should we warn on this?
}

extern "C" { // expected-note 2 {{extern "C" language linkage specification begins here}}
  class PR17968 {
    template<typename T> class D; // expected-error{{templates must have C++ linkage}}
    template<typename T> void f(); // expected-error{{templates must have C++ linkage}}
  };
}

template<class U> class A; // expected-note{{previous template declaration is here}}

template<int N> class A; // expected-error{{template parameter has a different kind in template redeclaration}}

template<int N> class NonTypeTemplateParm;

typedef int INT;

template<INT M> class NonTypeTemplateParm; // expected-note{{previous non-type template parameter with type 'INT' (aka 'int') is here}}

template<long> class NonTypeTemplateParm; // expected-error{{template non-type parameter has a different type 'long' in template redeclaration}}

template<template<typename T> class X> class TemplateTemplateParm;

template<template<class> class Y> class TemplateTemplateParm; // expected-note{{previous template declaration is here}} \
      // expected-note{{previous template template parameter is here}}

template<typename> class TemplateTemplateParm; // expected-error{{template parameter has a different kind in template redeclaration}}

template<template<typename T, int> class X> class TemplateTemplateParm; // expected-error{{too many template parameters in template template parameter redeclaration}}

template<typename T>
struct test {}; // expected-note{{previous definition}}

template<typename T>
struct test : T {}; // expected-error{{redefinition}}

class X {
public:
  template<typename T> class C;
};

void f() {
  template<typename T> class X; // expected-error{{expression}}
}

template<typename T> class X1 var; // expected-error {{variable has incomplete type 'class X1'}} \
                                   // expected-note {{forward declaration of 'X1'}}

namespace M {
}

template<typename T> class M::C3 { }; // expected-error{{out-of-line definition of 'C3' does not match any declaration in namespace 'M'}}

namespace PR8001 {
  template<typename T1>
  struct Foo {
    template<typename T2> class Bar;
    typedef Bar<T1> Baz;

   template<typename T2>
   struct Bar {
     Bar() {}
   };
  };

  void pr8001() {
    Foo<int>::Baz x;
    Foo<int>::Bar<int> y(x);
  }
}

namespace rdar9676205 {
  template <unsigned, class _Tp> class tuple_element;

  template <class _T1, class _T2> class pair;

  template <class _T1, class _T2>
  class tuple_element<0, pair<_T1, _T2> >
  {
    template <class _Tp>
    struct X
    {
      template <class _Up, bool = X<_Up>::value>
      struct Y
        : public X<_Up>,
          public Y<_Up>
      { };
    };
  };
}

namespace redecl {
  int A; // expected-note {{here}}
  template<typename T> struct A; // expected-error {{different kind of symbol}}

  int B; // expected-note {{here}}
  template<typename T> struct B { // expected-error {{different kind of symbol}}
  };

  template<typename T> struct F;
  template<typename T> struct K;

  int G, H; // expected-note {{here}}

  struct S {
    int C; // expected-note {{here}}
    template<typename T> struct C; // expected-error {{different kind of symbol}}

    int D; // expected-note {{here}}
    template<typename T> struct D { // expected-error {{different kind of symbol}}
    };

    int E;
    template<typename T> friend struct E { // expected-error {{cannot define a type in a friend}}
    };

    int F;
    template<typename T> friend struct F; // ok, redecl::F

    template<typename T> struct G; // ok

    template<typename T> friend struct H; // expected-error {{different kind of symbol}}

    int I, J, K;

    struct U {
      template<typename T> struct I; // ok
      template<typename T> struct J { // ok
      };
      template<typename T> friend struct K; // ok, redecl::K
    };
  };
}

extern "C" template <typename T> // expected-error{{templates must have C++ linkage}}
void DontCrashOnThis() { // expected-note@-1 {{extern "C" language linkage specification begins here}}
  T &pT = T();
  pT;
}

namespace abstract_dependent_class {
  template<typename T> struct A {
    virtual A<T> *clone() = 0; // expected-note {{pure virtual}}
  };
  template<typename T> A<T> *A<T>::clone() { return new A<T>; } // expected-error {{abstract class type 'A<T>'}}
}

namespace qualified_out_of_line {
  struct rbnode {};
  template<typename T, typename U> struct pair {};
  template<typename K, typename V> struct rbtree {
    using base = rbnode;
    pair<base, base> f();
  };
  template<typename K, typename V>
  pair<typename rbtree<K, V>::base, typename rbtree<K, V>::base>
  rbtree<K, V>::f() {
    return {};
  }
}