clang/test/SemaTemplate/nested-deduction-guides.cpp

   1 // RUN: %clang_cc1 -std=c++17 -verify %s
   2
   3 template<typename T> struct A {
   4   template<typename U> struct B {
   5     B(...);
   6     B(const B &) = default;
   7   };
   8   template<typename U> B(U) -> B<U>;
   9 };
  10 A<void>::B b = 123;
  11 A<void>::B copy = b;
  12
  13 using T = decltype(b);
  14 using T = A<void>::B<int>;
  15
  16 using Copy = decltype(copy);
  17 using Copy = A<void>::B<int>;
  18
  19 namespace GH94614 {
  20
  21 template <class, class> struct S {};
  22
  23 struct trouble_1 {
  24 } constexpr t1;
  25 struct trouble_2 {
  26 } constexpr t2;
  27 struct trouble_3 {
  28 } constexpr t3;
  29 struct trouble_4 {
  30 } constexpr t4;
  31 struct trouble_5 {
  32 } constexpr t5;
  33 struct trouble_6 {
  34 } constexpr t6;
  35 struct trouble_7 {
  36 } constexpr t7;
  37 struct trouble_8 {
  38 } constexpr t8;
  39 struct trouble_9 {
  40 } constexpr t9;
  41
  42 template <class U, class... T> struct Unrelated {
  43   using Trouble = S<U, T...>;
  44
  45   template <class... V> using Trouble2 = S<V..., T...>;
  46 };
  47
  48 template <class T, class U> struct Outer {
  49   using Trouble = S<U, T>;
  50
  51   template <class V> using Trouble2 = S<V, T>;
  52
  53   template <class V> using Trouble3 = S<U, T>;
  54
  55   template <class V> struct Inner {
  56     template <class W> struct Paranoid {
  57       using Trouble4 = S<W, T>;
  58
  59       template <class... X> using Trouble5 = S<X..., T>;
  60     };
  61
  62     Inner(trouble_1, V v, Trouble trouble) {}
  63     Inner(trouble_2, V v, Trouble2<V> trouble) {}
  64     Inner(trouble_3, V v, Trouble3<V> trouble) {}
  65     Inner(trouble_4, V v, typename Unrelated<U, T>::template Trouble2<V> trouble) {}
  66     Inner(trouble_5, V v, typename Unrelated<U, T>::Trouble trouble) {}
  67     Inner(trouble_6, V v, typename Unrelated<V, T>::Trouble trouble) {}
  68     Inner(trouble_7, V v, typename Paranoid<V>::Trouble4 trouble) {}
  69     Inner(trouble_8, V v, typename Paranoid<V>::template Trouble5<V> trouble) {}
  70     template <class W>
  71     Inner(trouble_9, V v, W w, typename Paranoid<V>::template Trouble5<W> trouble) {}
  72   };
  73 };
  74
  75 S<int, char> s;
  76
  77 Outer<char, int>::Inner _1(t1, 42, s);
  78 Outer<char, int>::Inner _2(t2, 42, s);
  79 Outer<char, int>::Inner _3(t3, 42, s);
  80 Outer<char, int>::Inner _4(t4, 42, s);
  81 Outer<char, int>::Inner _5(t5, 42, s);
  82 Outer<char, int>::Inner _6(t6, 42, s);
  83 Outer<char, int>::Inner _7(t7, 42, s);
  84 Outer<char, int>::Inner _8(t8, 42, s);
  85 Outer<char, int>::Inner _9(t9, 42, 24, s);
  86
  87 // Make sure we don't accidentally inject the TypedefNameDecl into the TU.
  88 Trouble should_not_be_in_the_tu_decl; // expected-error {{unknown type name 'Trouble'}}
  89
  90 } // namespace GH94614