clang/test/CXX/dcl.decl/dcl.decomp/p4.cpp

   1 // RUN: %clang_cc1 -std=c++1z -verify -triple i686-linux-gnu %s
   2
   3 template<typename T, typename U> struct same;
   4 template<typename T> struct same<T, T> { ~same(); };
   5
   6 struct Empty {};
   7
   8 struct A {
   9   int a;
  10 };
  11
  12 namespace NonPublicMembers {
  13   struct NonPublic1 {
  14   protected:
  15     int a; // expected-note {{declared protected here}}
  16   };
  17
  18   struct NonPublic2 {
  19   private:
  20     int a; // expected-note 2{{declared private here}}
  21   };
  22
  23   struct NonPublic3 : private A {}; // expected-note {{declared private here}}
  24
  25   struct NonPublic4 : NonPublic2 {};
  26
  27   void test() {
  28     auto [a1] = NonPublic1(); // expected-error {{cannot decompose protected member 'a' of 'NonPublicMembers::NonPublic1'}}
  29     auto [a2] = NonPublic2(); // expected-error {{cannot decompose private member 'a' of 'NonPublicMembers::NonPublic2'}}
  30     auto [a3] = NonPublic3(); // expected-error {{cannot decompose members of inaccessible base class 'A' of 'NonPublicMembers::NonPublic3'}}
  31     auto [a4] = NonPublic4(); // expected-error {{cannot decompose private member 'a' of 'NonPublicMembers::NonPublic2'}}
  32   }
  33 }
  34
  35 namespace AnonymousMember {
  36   struct Struct {
  37     struct { // expected-note {{declared here}}
  38       int i;
  39     };
  40   };
  41
  42   struct Union {
  43     union { // expected-note {{declared here}}
  44       int i;
  45     };
  46   };
  47
  48   void test() {
  49     auto [a1] = Struct(); // expected-error {{cannot decompose class type 'Struct' because it has an anonymous struct member}}
  50     auto [a2] = Union(); // expected-error {{cannot decompose class type 'Union' because it has an anonymous union member}}
  51   }
  52 }
  53
  54 namespace MultipleClasses {
  55   struct B : A {
  56     int a;
  57   };
  58
  59   struct C { int a; };
  60   struct D : A, C {};
  61
  62   struct E : virtual A {};
  63   struct F : A, E {}; // expected-warning {{direct base 'A' is inaccessible due to ambiguity}}
  64
  65   struct G : virtual A {};
  66   struct H : E, G {};
  67
  68   struct I { int i; };
  69   struct J : I {};
  70   struct K : I, virtual J {}; // expected-warning {{direct base 'I' is inaccessible due to ambiguity}}
  71
  72   struct L : virtual J {};
  73   struct M : virtual J, L {};
  74
  75   void test() {
  76     auto [b] = B(); // expected-error {{cannot decompose class type 'B': both it and its base class 'A' have non-static data members}}
  77     auto [d] = D(); // expected-error {{cannot decompose class type 'D': its base classes 'A' and 'C' have non-static data members}}
  78     auto [e] = E();
  79     auto [f] = F(); // expected-error-re {{cannot decompose members of ambiguous base class 'A' of 'F':{{.*}}struct MultipleClasses::F -> A{{.*}}struct MultipleClasses::F -> E -> A}}
  80     auto [h] = H(); // ok, only one (virtual) base subobject even though there are two paths to it
  81     auto [k] = K(); // expected-error {{cannot decompose members of ambiguous base class 'I'}}
  82     auto [m] = M(); // ok, all paths to I are through the same virtual base subobject J
  83
  84     same<decltype(m), int>();
  85   }
  86 }
  87
  88 namespace BindingTypes {
  89   struct A {
  90     int i = 0;
  91     int &r = i;
  92     const float f = i;
  93     mutable volatile int mvi;
  94   };
  95   void e() {
  96     auto [i,r,f,mvi] = A();
  97
  98     same<decltype(i), int>();
  99     same<decltype(r), int&>();
 100     same<decltype(f), const float>();
 101     same<decltype(mvi), volatile int>();
 102
 103     same<decltype((i)), int&>();
 104     same<decltype((r)), int&>();
 105     same<decltype((f)), const float&>();
 106     same<decltype((mvi)), volatile int&>();
 107   }
 108   void f() {
 109     auto &&[i,r,f,mvi] = A();
 110
 111     same<decltype(i), int>();
 112     same<decltype(r), int&>();
 113     same<decltype(f), const float>();
 114     same<decltype(mvi), volatile int>();
 115
 116     same<decltype((i)), int&>();
 117     same<decltype((r)), int&>();
 118     same<decltype((f)), const float&>();
 119     same<decltype((mvi)), volatile int&>();
 120   }
 121   void g() {
 122     const auto [i,r,f,mvi] = A();
 123
 124     same<decltype(i), const int>();
 125     same<decltype(r), int&>();
 126     same<decltype(f), const float>();
 127     same<decltype(mvi), volatile int>(); // not 'const volatile int', per expected resolution of DRxxx
 128
 129     same<decltype((i)), const int&>();
 130     same<decltype((r)), int&>();
 131     same<decltype((f)), const float&>();
 132     same<decltype((mvi)), volatile int&>(); // not 'const volatile int&', per expected resolution of DRxxx
 133   }
 134   void h() {
 135     typedef const A CA;
 136     auto &[i,r,f,mvi] = CA(); // type of var is 'const A &'
 137
 138     same<decltype(i), const int>(); // not 'int', per expected resolution of DRxxx
 139     same<decltype(r), int&>();
 140     same<decltype(f), const float>();
 141     same<decltype(mvi), volatile int>(); // not 'const volatile int', per expected resolution of DRxxx
 142
 143     same<decltype((i)), const int&>(); // not 'int&', per expected resolution of DRxxx
 144     same<decltype((r)), int&>();
 145     same<decltype((f)), const float&>();
 146     same<decltype((mvi)), volatile int&>(); // not 'const volatile int&', per expected resolution of DRxxx
 147   }
 148   struct B {
 149     mutable int i;
 150   };
 151   void mut() {
 152     auto [i] = B();
 153     const auto [ci] = B();
 154     volatile auto [vi] = B();
 155     same<decltype(i), int>();
 156     same<decltype(ci), int>();
 157     same<decltype(vi), volatile int>();
 158   }
 159 }
 160
 161 namespace Bitfield {
 162   struct S { unsigned long long x : 4, y : 32; int z; }; // expected-note 2{{here}}
 163   int f(S s) {
 164     auto [a, b, c] = s;
 165     unsigned long long &ra = a; // expected-error {{bit-field 'x'}}
 166     unsigned long long &rb = b; // expected-error {{bit-field 'y'}}
 167     int &rc = c;
 168
 169     // the type of the binding is the type of the field
 170     same<decltype(a), unsigned long long>();
 171     same<decltype(b), unsigned long long>();
 172
 173     // the type of the expression is an lvalue of the field type
 174     // (even though a reference can't bind to the field)
 175     same<decltype((a)), unsigned long long&>();
 176     same<decltype((b)), unsigned long long&>();
 177
 178     // the expression promotes to a type large enough to hold the result
 179     same<decltype(+a), int>();
 180     same<decltype(+b), unsigned int>();
 181     return rc;
 182   }
 183 }
 184
 185 namespace Constexpr {
 186   struct Q { int a, b; constexpr Q() : a(1), b(2) {} };
 187   constexpr Q q;
 188   auto &[qa, qb] = q;
 189   static_assert(&qa == &q.a && &qb == &q.b);
 190   static_assert(qa == 1 && qb == 2);
 191 }
 192
 193 namespace std_example {
 194   struct S { int x1 : 2; volatile double y1; };
 195   S f();
 196   const auto [x, y] = f();
 197
 198   same<decltype((x)), const int&> same1;
 199   same<decltype((y)), const volatile double&> same2;
 200 }
 201
 202 namespace p0969r0 {
 203   struct A {
 204     int x;
 205     int y;
 206   };
 207   struct B : private A { // expected-note {{declared private here}}
 208     void test_member() {
 209       auto &[x, y] = *this;
 210     }
 211     friend void test_friend(B);
 212   };
 213   void test_friend(B b) {
 214     auto &[x, y] = b;
 215   }
 216   void test_external(B b) {
 217     auto &[x, y] = b; // expected-error {{cannot decompose members of inaccessible base class 'A' of 'p0969r0::B'}}
 218   }
 219
 220   struct C {
 221     int x;
 222   protected:
 223     int y; // expected-note {{declared protected here}} expected-note {{can only access this member on an object of type 'p0969r0::D'}}
 224     void test_member() {
 225       auto &[x, y] = *this;
 226     }
 227     friend void test_friend(struct D);
 228   };
 229   struct D : C {
 230     static void test_member(D d, C c) {
 231       auto &[x1, y1] = d;
 232       auto &[x2, y2] = c; // expected-error {{cannot decompose protected member 'y' of 'p0969r0::C'}}
 233     }
 234   };
 235   void test_friend(D d) {
 236     auto &[x, y] = d;
 237   }
 238   void test_external(D d) {
 239     auto &[x, y] = d; // expected-error {{cannot decompose protected member 'y' of 'p0969r0::C'}}
 240   }
 241 }