clang/test/Parser/cxx1z-class-template-argument-deduction.cpp

   1 // RUN: %clang_cc1 -std=c++1z -fcxx-exceptions -verify %s
   2
   3 template <typename T> struct A { // expected-note 38{{declared here}}
   4   constexpr A() {}
   5   constexpr A(int) {}
   6   constexpr operator int() { return 0; }
   7 };
   8 A() -> A<int>;
   9 A(int) -> A<int>;
  10
  11 // Make sure we still correctly parse cases where a template can appear without arguments.
  12 namespace template_template_arg {
  13   template<template<typename> typename> struct X {};
  14   template<typename> struct Y {};
  15
  16   X<A> xa;
  17   Y<A> ya; // expected-error {{requires template arguments}}
  18   X<::A> xcca;
  19   Y<::A> ycca; // expected-error {{requires template arguments}}
  20   X<A*> xap; // expected-error {{requires template arguments}}
  21   X<const A> xca; // expected-error {{requires template arguments}}
  22   X<A const> xac; // expected-error {{requires template arguments}}
  23   // FIXME: This should not parse as a template template argument due to the
  24   // trailing attributes.
  25   X<A [[]]> xa_attr;
  26
  27   template<template<typename> typename = A> struct XD {};
  28   template<typename = A> struct YD {}; // expected-error {{requires template arguments}}
  29   template<template<typename> typename = ::A> struct XCCD {};
  30   template<typename = ::A> struct YCCD {}; // expected-error {{requires template arguments}}
  31
  32   // FIXME: replacing the invalid type with 'int' here is horrible
  33   template <A a = A<int>()> class C { }; // expected-error {{requires template arguments}}
  34   template<typename T = A> struct G { }; // expected-error {{requires template arguments}}
  35 }
  36
  37 namespace template_template_arg_pack {
  38   template<template<typename> typename...> struct XP {};
  39   template<typename...> struct YP {};
  40
  41   struct Z { template<typename T> struct Q {}; }; // expected-note 2{{here}}
  42
  43   template<typename T> using ZId = Z;
  44
  45   template<typename ...Ts> struct A {
  46     XP<ZId<Ts>::Q...> xe;
  47     YP<ZId<Ts>::Q...> ye; // expected-error {{requires template arguments}}
  48
  49     XP<ZId<Ts>::Q> xp; // expected-error {{unexpanded parameter pack}}
  50     YP<ZId<Ts>::Q> yp; // expected-error {{requires template arguments}}
  51   };
  52 }
  53
  54 namespace injected_class_name {
  55   template<typename T> struct A {
  56     A(T);
  57     void f(int) { // expected-note {{previous}}
  58       A a = 1;
  59       injected_class_name::A b = 1; // expected-note {{in instantiation of template class 'injected_class_name::A<int>'}}
  60     }
  61     void f(T); // expected-error {{multiple overloads of 'f' instantiate to the same signature 'void (int)}}
  62   };
  63   A<short> ai = 1;
  64   A<double>::A b(1); // expected-error {{constructor name}}
  65 }
  66
  67 struct member {
  68   A a; // expected-error {{requires template arguments}}
  69   A *b; // expected-error {{requires template arguments}}
  70   const A c; // expected-error {{requires template arguments}}
  71
  72   void f() throw (A); // expected-error {{requires template arguments}}
  73
  74   friend A; // expected-error {{requires template arguments; argument deduction not allowed in friend declaration}}
  75
  76   operator A(); // expected-error {{requires template arguments; argument deduction not allowed in conversion function type}}
  77
  78   static A x; // expected-error {{declaration of variable 'x' with deduced type 'A' requires an initializer}}
  79   static constexpr A y = 0;
  80 };
  81
  82 namespace in_typedef {
  83   typedef A *AutoPtr; // expected-error {{requires template arguments; argument deduction not allowed in typedef}}
  84   typedef A (*PFun)(int a); // expected-error{{requires template arguments; argument deduction not allowed in typedef}}
  85   typedef A Fun(int a) -> decltype(a + a); // expected-error{{requires template arguments; argument deduction not allowed in function return type}}
  86 }
  87
  88 namespace stmt {
  89   void g(A a) { // expected-error{{requires template arguments; argument deduction not allowed in function prototype}}
  90     try { }
  91     catch (A &a) { } // expected-error{{requires template arguments; argument deduction not allowed in exception declaration}}
  92     catch (const A a) { } // expected-error{{requires template arguments; argument deduction not allowed in exception declaration}}
  93     try { } catch (A a) { } // expected-error{{requires template arguments; argument deduction not allowed in exception declaration}}
  94
  95     // FIXME: The standard only permits class template argument deduction in a
  96     // simple-declaration or cast. We also permit it in conditions,
  97     // for-range-declarations, member-declarations for static data members, and
  98     // new-expressions, because not doing so would be bizarre.
  99     A local = 0;
 100     static A local_static = 0;
 101     static thread_local A thread_local_static = 0;
 102     if (A a = 0) {}
 103     if (A a = 0; a) {}
 104     switch (A a = 0) {} // expected-warning {{no case matching constant switch condition '0'}}
 105     switch (A a = 0; a) {} // expected-warning {{no case matching constant switch condition '0'}}
 106     for (A a = 0; a; /**/) {}
 107     for (/**/; A a = 0; /**/) {}
 108     while (A a = 0) {}
 109     int arr[3];
 110     for (A a : arr) {}
 111   }
 112
 113   namespace std {
 114     class type_info;
 115   }
 116 }
 117
 118 namespace expr {
 119   template<typename T> struct U {};
 120   void j() {
 121     (void)typeid(A); // expected-error{{requires template arguments; argument deduction not allowed here}}
 122     (void)sizeof(A); // expected-error{{requires template arguments; argument deduction not allowed here}}
 123     (void)__alignof(A); // expected-error{{requires template arguments; argument deduction not allowed here}}
 124
 125     U<A> v; // expected-error {{requires template arguments}}
 126
 127     int n;
 128     (void)dynamic_cast<A&>(n); // expected-error{{requires template arguments; argument deduction not allowed here}}
 129     (void)static_cast<A*>(&n); // expected-error{{requires template arguments; argument deduction not allowed here}}
 130     (void)reinterpret_cast<A*>(&n); // expected-error{{requires template arguments; argument deduction not allowed here}}
 131     (void)const_cast<A>(n); // expected-error{{requires template arguments; argument deduction not allowed here}}
 132     (void)*(A*)(&n); // expected-error{{requires template arguments; argument deduction not allowed here}}
 133     (void)(A)(n); // expected-error{{requires template arguments; argument deduction not allowed here}}
 134     (void)(A){n}; // expected-error{{requires template arguments; argument deduction not allowed here}}
 135
 136     (void)A(n);
 137     (void)A{n};
 138     (void)new A(n);
 139     (void)new A{n};
 140     (void)new A;
 141   }
 142 }
 143
 144 namespace decl {
 145   enum E : A {}; // expected-error{{requires template arguments; argument deduction not allowed here}}
 146   struct F : A {}; // expected-error{{expected class name}}
 147
 148   using B = A; // expected-error{{requires template arguments}}
 149
 150   auto k() -> A; // expected-error{{requires template arguments}}
 151
 152   A a;
 153   A b = 0;
 154   const A c = 0;
 155   A (parens) = 0; // expected-error {{cannot use parentheses when declaring variable with deduced class template specialization type}}
 156   A *p = 0; // expected-error {{cannot form pointer to deduced class template specialization type}}
 157   A &r = *p; // expected-error {{cannot form reference to deduced class template specialization type}}
 158   A arr[3] = 0; // expected-error {{cannot form array of deduced class template specialization type}}
 159   A F::*pm = 0; // expected-error {{cannot form pointer to deduced class template specialization type}}
 160   A (*fp)() = 0; // expected-error {{cannot form function returning deduced class template specialization type}}
 161   A [x, y] = 0; // expected-error {{cannot be declared with type 'A'}} expected-error {{type 'A<int>' decomposes into 0 elements, but 2 names were provided}}
 162 }
 163
 164 namespace typename_specifier {
 165   struct F {};
 166
 167   void e() {
 168     (void) typename ::A(0);
 169     (void) typename ::A{0};
 170     new typename ::A(0);
 171     new typename ::A{0};
 172     typename ::A a = 0;
 173     const typename ::A b = 0;
 174     if (typename ::A a = 0) {}
 175     for (typename ::A a = 0; typename ::A b = 0; /**/) {}
 176
 177     (void)(typename ::A)(0); // expected-error{{requires template arguments; argument deduction not allowed here}}
 178     (void)(typename ::A){0}; // expected-error{{requires template arguments; argument deduction not allowed here}}
 179   }
 180   typename ::A a = 0;
 181   const typename ::A b = 0;
 182   typename ::A (parens) = 0; // expected-error {{cannot use parentheses when declaring variable with deduced class template specialization type}}
 183   typename ::A *p = 0; // expected-error {{cannot form pointer to deduced class template specialization type}}
 184   typename ::A &r = *p; // expected-error {{cannot form reference to deduced class template specialization type}}
 185   typename ::A arr[3] = 0; // expected-error {{cannot form array of deduced class template specialization type}}
 186   typename ::A F::*pm = 0; // expected-error {{cannot form pointer to deduced class template specialization type}}
 187   typename ::A (*fp)() = 0; // expected-error {{cannot form function returning deduced class template specialization type}}
 188   typename ::A [x, y] = 0; // expected-error {{cannot be declared with type 'typename ::A'}} expected-error {{type 'typename ::A<int>' (aka 'A<int>') decomposes into 0}}
 189
 190   struct X { template<typename T> struct A { A(T); }; }; // expected-note 8{{declared here}}
 191
 192   template<typename T> void f() {
 193     (void) typename T::A(0);
 194     (void) typename T::A{0};
 195     new typename T::A(0);
 196     new typename T::A{0};
 197     typename T::A a = 0;
 198     const typename T::A b = 0;
 199     if (typename T::A a = 0) {} // expected-error {{value of type 'typename X::A<int>' (aka 'typename_specifier::X::A<int>') is not contextually convertible to 'bool'}}
 200     for (typename T::A a = 0; typename T::A b = 0; /**/) {} // expected-error {{value of type 'typename X::A<int>' (aka 'typename_specifier::X::A<int>') is not contextually convertible to 'bool'}}
 201
 202     {(void)(typename T::A)(0);} // expected-error{{refers to class template member}}
 203     {(void)(typename T::A){0};} // expected-error{{refers to class template member}}
 204     {typename T::A (parens) = 0;} // expected-error {{refers to class template member in 'typename_specifier::X'; argument deduction not allowed here}}
 205     // expected-warning@-1 {{disambiguated as redundant parentheses around declaration of variable named 'parens'}} expected-note@-1 {{add a variable name}} expected-note@-1{{remove parentheses}} expected-note@-1 {{add enclosing parentheses}}
 206     {typename T::A *p = 0;} // expected-error {{refers to class template member}}
 207     {typename T::A &r = *p;} // expected-error {{refers to class template member}}
 208     {typename T::A arr[3] = 0;} // expected-error {{refers to class template member}}
 209     {typename T::A F::*pm = 0;} // expected-error {{refers to class template member}}
 210     {typename T::A (*fp)() = 0;} // expected-error {{refers to class template member}}
 211     {typename T::A [x, y] = 0;} // expected-error {{cannot be declared with type 'typename T::A'}} expected-error {{type 'typename X::A<int>' (aka 'typename_specifier::X::A<int>') decomposes into 0}}
 212   }
 213   template void f<X>(); // expected-note {{instantiation of}}
 214
 215   template<typename T> void g(typename T::A = 0); // expected-note {{refers to class template member}}
 216   void h() { g<X>(); } // expected-error {{no matching function}}
 217 }
 218
 219 namespace parenthesized {
 220   template<typename T> struct X { X(T); };
 221   auto n = (X([]{}));
 222 }
 223
 224 namespace within_template_arg_list {
 225   template<typename T> struct X { constexpr X(T v) : v(v) {} T v; };
 226   template<int N = X(1).v> struct Y {};
 227   using T = Y<>;
 228   using T = Y<X(1).v>;
 229   using T = Y<within_template_arg_list::X(1).v>;
 230
 231   template<int ...N> struct Z { Y<X(N)...> y; };
 232 }
 233
 234 namespace PR49735 {
 235 // Ensure that we do not crash when parsing code which looks like an invalid
 236 // deduction guide declaration.
 237 template<class> struct B; // expected-note 2{{template is declared here}}
 238 struct A1 {
 239   B() noexcept(false); // expected-error {{deduction guide must be declared in the same scope as template 'PR49735::B'}} \
 240                        // expected-error {{deduction guide declaration without trailing return type}}
 241 };
 242
 243 struct A2 {
 244   template <typename Ty> // expected-note {{non-deducible template parameter 'Ty'}}
 245   B() noexcept(false); // expected-error {{deduction guide must be declared in the same scope as template 'PR49735::B'}} \
 246                        // expected-error {{deduction guide template contains a template parameter that cannot be deduced}} \
 247                        // expected-error {{deduction guide declaration without trailing return type}}
 248 };
 249
 250 }