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      1 // RUN: %clang_cc1 -std=c++11 -verify %s
      2 
      3 namespace std_example {
      4 
      5 template<class T> struct A { ~A() = delete; }; // expected-note {{deleted here}}
      6 template<class T> auto h() -> A<T>;
      7 template<class T> auto i(T) -> T;
      8 template<class T> auto f(T) -> decltype(i(h<T>())); // #1
      9 template<class T> auto f(T) -> void; // #2
     10 auto g() -> void {
     11   f(42); // ok, calls #2, since #1 is not viable.
     12 }
     13 template<class T> auto q(T) -> decltype((h<T>()));
     14 void r() {
     15   // Deduction against q succeeds, but results in a temporary which can't be
     16   // destroyed.
     17   q(42); // expected-error {{attempt to use a deleted function}}
     18 }
     19 
     20 }
     21 
     22 class PD {
     23   friend struct A;
     24   ~PD(); // expected-note 4{{here}}
     25 public:
     26   typedef int n;
     27 };
     28 struct DD {
     29   ~DD() = delete; // expected-note 2{{here}}
     30   typedef int n;
     31 };
     32 
     33 struct A {
     34   decltype(PD()) s; // ok
     35   decltype(PD())::n n; // ok
     36   decltype(DD()) *p = new decltype(DD()); // ok
     37 };
     38 
     39 // Two errors here: one for the decltype, one for the variable.
     40 decltype(PD(), PD()) pd1; // expected-error 2{{private destructor}}
     41 decltype(DD(), DD()) dd1; // expected-error 2{{deleted function}}
     42 
     43 decltype(((13, ((DD())))))::n dd_parens; // ok
     44 decltype(((((42)), PD())))::n pd_parens_comma; // ok
     45 
     46 // Ensure parens aren't stripped from a decltype node.
     47 extern decltype(PD()) pd_ref; // ok
     48 decltype((pd_ref)) pd_ref3 = pd_ref; // ok, PD &
     49 decltype(pd_ref) pd_ref2 = pd_ref; // expected-error {{private destructor}}
     50 
     51 namespace libcxx_example {
     52   struct nat {
     53     nat() = delete;
     54     nat(const nat&) = delete;
     55     nat &operator=(const nat&) = delete;
     56     ~nat() = delete;
     57   };
     58   struct any {
     59     any(...);
     60   };
     61 
     62   template<typename T, typename U> struct is_same { static const bool value = false; };
     63   template<typename T> struct is_same<T, T> { static const bool value = true; };
     64 
     65   template<typename T> T declval();
     66 
     67   void swap(int &a, int &b);
     68   nat swap(any, any);
     69 
     70   template<typename T> struct swappable {
     71     typedef decltype(swap(declval<T&>(), declval<T&>())) type;
     72     static const bool value = !is_same<type, nat>::value;
     73     constexpr operator bool() { return value; }
     74   };
     75 
     76   static_assert(swappable<int>(), "");
     77   static_assert(!swappable<const int>(), "");
     78 }
     79 
     80 namespace RequireCompleteType {
     81   template<int N, bool OK> struct S {
     82     static_assert(OK, "boom!"); // expected-error 2{{boom!}}
     83   };
     84 
     85   template<typename T> T make();
     86   template<int N, bool OK> S<N, OK> make();
     87   void consume(...);
     88 
     89   decltype(make<0, false>()) *p1; // ok
     90   decltype((make<1, false>())) *p2; // ok
     91 
     92   // A complete type is required here in order to detect an overloaded 'operator,'.
     93   decltype(123, make<2, false>()) *p3; // expected-note {{here}}
     94 
     95   decltype(consume(make<3, false>())) *p4; // expected-note {{here}}
     96 
     97   decltype(make<decltype(make<4, false>())>()) *p5; // ok
     98 }
     99 
    100 namespace Overload {
    101   DD operator+(PD &a, PD &b);
    102   decltype(PD()) *pd_ptr;
    103   decltype(*pd_ptr + *pd_ptr) *dd_ptr; // ok
    104 
    105   decltype(0, *pd_ptr) pd_ref2 = pd_ref; // ok
    106   DD operator,(int a, PD b);
    107   decltype(0, *pd_ptr) *dd_ptr2; // expected-error {{private destructor}}
    108 }
    109