llvm-project/clang/test/SemaTemplate/constructor-template.cpp

// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx17 %std_cxx98-14 %s
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s

struct X0 { // expected-note {{candidate constructor (the implicit copy constructor) not viable}}
#if __cplusplus >= 201103L // C++11 or later
// expected-note@-2 {{candidate constructor (the implicit move constructor) not viable}}
#endif
  X0(int); // expected-note{{candidate}}
  template<typename T> X0(T); // expected-note {{candidate}}
  template<typename T, typename U> X0(T*, U*); // expected-note {{candidate}}
  
  // PR4761
  template<typename T> X0() : f0(T::foo) {} // expected-note {{candidate}}
  int f0;
};

void accept_X0(X0);

void test_X0(int i, float f) {
  X0 x0a(i);
  X0 x0b(f);
  X0 x0c = i;
  X0 x0d = f;
  accept_X0(i);
  accept_X0(&i);
  accept_X0(f);
  accept_X0(&f);
  X0 x0e(&i, &f);
  X0 x0f(&f, &i);
  
  X0 x0g(f, &i); // expected-error{{no matching constructor}}
}

template<typename T>
struct X1 {
  X1(const X1&);
  template<typename U> X1(const X1<U>&);
};

template<typename T>
struct Outer {
  typedef X1<T> A;
  
  A alloc;
  
  explicit Outer(const A& a) : alloc(a) { }
};

void test_X1(X1<int> xi) {
  Outer<int> oi(xi);
  Outer<float> of(xi);
}

// PR4655
template<class C> struct A {};
template <> struct A<int>{A(const A<int>&);};
struct B { A<int> x; B(B& a) : x(a.x) {} };

struct X2 {
  X2(); // precxx17-note{{candidate constructor}}
  X2(X2&);	// precxx17-note {{candidate constructor}}
  template<typename T> X2(T); // precxx17-note {{candidate template ignored: instantiation would take its own class type by value}}
};

X2 test(bool Cond, X2 x2) {
  if (Cond)
    return x2; // okay, uses copy constructor
  
  return X2(); // precxx17-error{{no matching constructor}}
}

struct X3 {
  template<typename T> X3(T);
};

template<> X3::X3(X3); // expected-error{{must pass its first argument by reference}}

struct X4 {
  X4();
  ~X4();
  X4(X4&);
  template<typename T> X4(const T&, int = 17);
};

X4 test_X4(bool Cond, X4 x4) {
  X4 a(x4, 17); // okay, constructor template
  X4 b(x4); // okay, copy constructor
  return X4();
}

// Instantiation of a non-dependent use of a constructor
struct DefaultCtorHasDefaultArg {
  explicit DefaultCtorHasDefaultArg(int i = 17);
};

template<typename T>
void default_ctor_inst() {
  DefaultCtorHasDefaultArg def;
}

template void default_ctor_inst<int>();

template<typename T>
struct X5 {
  X5();
  X5(const T &);
};

struct X6 {
  template<typename T> X6(T);
};

void test_X5_X6() {
  X5<X6> tf;
  X5<X6> tf2(tf);
}

namespace PR8182 {
  struct foo {
    foo();
    template<class T> foo(T&);

  private:
    foo(const foo&);
  };

  void test_foo() {
    foo f1;
    foo f2(f1);
    foo f3 = f1;
  }

}

// Don't blow out the stack trying to call an illegal constructor
// instantiation.  We intentionally allow implicit instantiations to
// exist, so make sure they're unusable.
//
// rdar://19199836
namespace self_by_value {
  template <class T, class U> struct A {
    A() {}
    A(const A<T,U> &o) {}
    A(A<T,T> o) {}
  };

  void helper(A<int,float>);

  void test1(A<int,int> a) {
    helper(a);
  }
  void test2() {
    helper(A<int,int>());
  }
}

namespace self_by_value_2 {
  template <class T, class U> struct A {
    A() {} // precxx17-note {{not viable: requires 0 arguments}}
    A(A<T,U> &o) {} // precxx17-note {{not viable: expects an lvalue}}
    A(A<T,T> o) {} // precxx17-note {{ignored: instantiation takes its own class type by value}}
  };

  void helper_A(A<int,int>); // precxx17-note {{passing argument to parameter here}}
  void test_A() {
    helper_A(A<int,int>()); // precxx17-error {{no matching constructor}}
  }
}

namespace self_by_value_3 {
  template <class T, class U> struct A {
    A() {}
    A(A<T,U> &o) {}
    A(A<T,T> o) {}
  };

  void helper_A(A<int,int>);
  void test_A(A<int,int> b) {
    helper_A(b);
  }
}