clang/test/CXX/dcl.decl/dcl.fct.def/dcl.fct.def.default/p1.cpp

   1 // RUN: %clang_cc1 -verify=expected,pre20 %s -std=c++11
   2 // RUN: %clang_cc1 -verify=expected,pre20 %s -std=c++17
   3 // RUN: %clang_cc1 -verify=expected %s -std=c++20
   4
   5 // A function that is explicitly defaulted shall
   6 struct A {
   7   // -- be a special member function [C++20: or a comparison operator function],
   8   A(int) = default;
   9 #if __cplusplus <= 201703L
  10   // expected-error@-2 {{only special member functions may be defaulted}}
  11 #else
  12   // expected-error@-4 {{only special member functions and comparison operators may be defaulted}}
  13 #endif
  14   A(A) = default; // expected-error {{must pass its first argument by reference}}
  15   void f(A) = default; // expected-error-re {{only special member functions{{( and comparison operators)?}} may be defaulted}}
  16
  17   bool operator==(const A&) const = default; // pre20-warning {{defaulted comparison operators are a C++20 extension}}
  18   bool operator!=(const A&) const = default; // pre20-warning {{defaulted comparison operators are a C++20 extension}}
  19   bool operator<(const A&) const = default; // pre20-error {{only special member functions may be defaulted}}
  20   bool operator>(const A&) const = default; // pre20-error {{only special member functions may be defaulted}}
  21   bool operator<=(const A&) const = default; // pre20-error {{only special member functions may be defaulted}}
  22   bool operator>=(const A&) const = default; // pre20-error {{only special member functions may be defaulted}}
  23   bool operator<=>(const A&) const = default; // pre20-error 1+{{}} pre20-warning {{'<=>' is a single token in C++20}}
  24
  25   A operator+(const A&) const = default; // expected-error-re {{only special member functions{{( and comparison operators)?}} may be defaulted}}
  26
  27   // -- have the same declared function type as if it had been implicitly
  28   //    declared
  29   void operator=(const A &) = default; // expected-error {{must return 'A &'}}
  30   A(...) = default;
  31   A(const A &, ...) = default;
  32   A &operator=(const A&) const = default;
  33   A &operator=(A) const = default; // expected-error {{must be an lvalue refe}}
  34 #if __cplusplus <= 201703L
  35   // expected-error@-5 {{cannot be variadic}}
  36   // expected-error@-5 {{cannot be variadic}}
  37   // expected-error@-5 {{may not have 'const'}}
  38   // expected-error@-5 {{may not have 'const'}}
  39 #else
  40   // expected-warning@-10 {{implicitly deleted}} expected-note@-10 {{declared type does not match the type of an implicit default constructor}}
  41   // expected-warning@-10 {{implicitly deleted}} expected-note@-10 {{declared type does not match the type of an implicit copy constructor}}
  42   // expected-warning@-10 {{implicitly deleted}} expected-note@-10 {{declared type does not match the type of an implicit copy assignment}}
  43 #endif
  44
  45   //    (except for possibly differing ref-qualifiers
  46   A &operator=(A &&) & = default;
  47
  48   //    and except that in the case of a copy constructor or copy assignment
  49   //    operator, the parameter type may be "reference to non-const T")
  50   A(A &) = default;
  51   A &operator=(A &) = default;
  52
  53   // -- not have default arguments
  54   A(double = 0.0) = default; // expected-error {{cannot have default arguments}}
  55   A(const A & = 0) = default; // expected-error {{cannot have default arguments}}
  56 };
  57
  58 struct A2 {
  59   A2(...);
  60   A2(const A2 &, ...);
  61   A2 &operator=(const A2&) const;
  62 };
  63 A2::A2(...) = default; // expected-error {{cannot be variadic}}
  64 A2::A2(const A2&, ...) = default; // expected-error {{cannot be variadic}}
  65 A2 &A2::operator=(const A2&) const = default; // expected-error {{may not have 'const'}}
  66
  67 struct B {
  68   B(B&);
  69   B &operator=(B&);
  70 };
  71 struct C : B {
  72   C(const C&) = default;
  73   C &operator=(const C&) = default;
  74 #if __cplusplus <= 201703L
  75   // expected-error@-3 {{is const, but a member or base requires it to be non-const}}
  76   // expected-error@-3 {{is const, but a member or base requires it to be non-const}}
  77 #else
  78   // expected-warning@-6 {{implicitly deleted}} expected-note@-6 {{type does not match}}
  79   // expected-warning@-6 {{implicitly deleted}} expected-note@-6 {{type does not match}}
  80 #endif
  81 };
  82
  83 struct D : B { // expected-note 2{{base class}}
  84   D(const D&);
  85   D &operator=(const D&);
  86 };
  87 D::D(const D&) = default; // expected-error {{would delete}} expected-error {{is const, but}}
  88 D &D::operator=(const D&) = default; // expected-error {{would delete}} expected-error {{is const, but}}