Bring inheriting constructor implementation up-to-date with current defect

reports, and implement implicit definition of inheriting constructors.
Remaining missing features: inheriting constructor templates, implicit
exception specifications for inheriting constructors, inheriting constructors
from dependent bases.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177320 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 231 insertions, 22 deletions

diff --git a/test/CXX/special/class.inhctor/elsewhere.cpp b/test/CXX/special/class.inhctor/elsewhere.cpp
index 09fd3d50dc..184e90298b 100644
--- a/test/CXX/special/class.inhctor/elsewhere.cpp
+++ b/test/CXX/special/class.inhctor/elsewhere.cpp
@@ -9,49 +9,49 @@ struct B1 {
   B1(int);
 };
 
-using B1::B1; // expected-error {{using declaration can not refer to class member}} expected-error {{not supported}}
+using B1::B1; // expected-error {{using declaration can not refer to class member}}
 
-// C++0x [namespace.udecl]p10:
+// C++11 [namespace.udecl]p10:
 //   A using-declaration is a declaration and can therefore be used repeatedly
 //   where (and only where) multiple declarations are allowed.
 
 struct I1 : B1 {
-  using B1::B1; // expected-note {{previous using declaration}} expected-error {{not supported}}
-  using B1::B1; // expected-error {{redeclaration of using decl}} expected-error {{not supported}}
+  using B1::B1; // expected-note {{previous using declaration}}
+  using B1::B1; // expected-error {{redeclaration of using decl}}
 };
 
-// C++0x [namespace.udecl]p3:
+// C++11 [namespace.udecl]p3:
 //   In a using declaration used as a member-declaration, the nested-name-
 //   specifier shall name a base class of the class being defined.
 //   If such a using-declaration names a constructor, the nested-name-specifier
 //   shall name a direct base class of the class being defined.
 
 struct D1 : I1 {
-  using B1::B1; // expected-error {{'B1' is not a direct base of 'D1', can not inherit constructors}} expected-error {{not supported}}
+  using B1::B1; // expected-error {{'B1' is not a direct base of 'D1', can not inherit constructors}}
 };
 
 template<typename T> struct A {};
 
 template<typename T> struct B : A<bool>, A<char> {
-  using A<T>::A; // expected-error {{'A<double>::', which is not a base class of 'B<double>'}} expected-error {{not supported}}
+  using A<T>::A; // expected-error {{'A<double>::', which is not a base class of 'B<double>'}}
 };
 B<bool> bb;
 B<char> bc;
 B<double> bd; // expected-note {{here}}
 
 template<typename T> struct C : A<T> {
-  using A<bool>::A; // expected-error {{'A<bool>::', which is not a base class of 'C<char>'}} expected-error {{not supported}}
+  using A<bool>::A; // expected-error {{'A<bool>::', which is not a base class of 'C<char>'}}
 };
 C<bool> cb;
 C<char> cc; // expected-note {{here}}
 
 template<typename T> struct D : A<T> {};
 template<typename T> struct E : D<T> {
-  using A<bool>::A; // expected-error {{'A<bool>' is not a direct base of 'E<bool>', can not inherit}} expected-error {{not supported}}
+  using A<bool>::A; // expected-error {{'A<bool>' is not a direct base of 'E<bool>', can not inherit}}
 };
 E<bool> eb; // expected-note {{here}}
 
 template<typename T> struct F : D<bool> {
-  using A<T>::A; // expected-error {{'A<bool>' is not a direct base of 'F<bool>'}} expected-error {{not supported}}
+  using A<T>::A; // expected-error {{'A<bool>' is not a direct base of 'F<bool>'}}
 };
 F<bool> fb; // expected-note {{here}}
diff --git a/test/CXX/special/class.inhctor/p1.cpp b/test/CXX/special/class.inhctor/p1.cpp
new file mode 100644
index 0000000000..57e91504d6
--- /dev/null
+++ b/test/CXX/special/class.inhctor/p1.cpp
@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -std=c++11 -verify %s
+// Per a core issue (no number yet), an ellipsis is always dropped.
+struct A {
+  A(...); // expected-note {{here}}
+  A(int = 0, int = 0, int = 0, int = 0, ...); // expected-note 5{{here}}
+  A(int = 0, int = 0, ...); // expected-note {{here}}
+};
+
+struct B : A { // expected-note 3{{candidate}}
+  using A::A; // expected-warning 3{{inheriting constructor does not inherit ellipsis}} expected-note 4{{candidate}} expected-note 2{{deleted}}
+};
+
+B b0{};
+// expected-error@-1 {{call to implicitly-deleted default constructor}}
+// expected-note@9 {{default constructor of 'B' is implicitly deleted because base class 'A' has multiple default constructors}}
+
+B b1{1};
+// FIXME: explain why the inheriting constructor was deleted
+// expected-error@-2 {{call to implicitly-deleted function of 'B'}}
+
+B b2{1,2};
+// expected-error@-1 {{call to implicitly-deleted function of 'B'}}
+
+B b3{1,2,3};
+// ok
+
+B b4{1,2,3,4};
+// ok
+
+B b5{1,2,3,4,5};
+// expected-error@-1 {{no matching constructor for initialization of 'B'}}
diff --git a/test/CXX/special/class.inhctor/p2.cpp b/test/CXX/special/class.inhctor/p2.cpp
new file mode 100644
index 0000000000..e4267385ce
--- /dev/null
+++ b/test/CXX/special/class.inhctor/p2.cpp
@@ -0,0 +1,87 @@
+// RUN: %clang_cc1 -std=c++11 -verify %s
+
+template<int> struct X {};
+
+// Constructor characteristics are:
+//   - the template parameter list [FIXME]
+//   - the parameter-type-list
+//   - absence or presence of explicit
+//   - absence or presence of constexpr
+struct A {
+  A(X<0>) {} // expected-note 2{{here}}
+  constexpr A(X<1>) {}
+  explicit A(X<2>) {} // expected-note 3{{here}}
+  explicit constexpr A(X<3>) {} // expected-note 2{{here}}
+};
+
+A a0 { X<0>{} };
+A a0i = { X<0>{} };
+constexpr A a0c { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
+constexpr A a0ic = { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
+
+A a1 { X<1>{} };
+A a1i = { X<1>{} };
+constexpr A a1c { X<1>{} };
+constexpr A a1ic = { X<1>{} };
+
+A a2 { X<2>{} };
+A a2i = { X<2>{} }; // expected-error {{constructor is explicit}}
+constexpr A a2c { X<2>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
+constexpr A a2ic = { X<2>{} }; // expected-error {{constructor is explicit}}
+
+A a3 { X<3>{} };
+A a3i = { X<3>{} }; // expected-error {{constructor is explicit}}
+constexpr A a3c { X<3>{} };
+constexpr A a3ic = { X<3>{} }; // expected-error {{constructor is explicit}}
+
+
+struct B : A {
+  using A::A; // expected-note 7{{here}}
+};
+
+B b0 { X<0>{} };
+B b0i = { X<0>{} };
+constexpr B b0c { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
+constexpr B b0ic = { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
+
+B b1 { X<1>{} };
+B b1i = { X<1>{} };
+constexpr B b1c { X<1>{} };
+constexpr B b1ic = { X<1>{} };
+
+B b2 { X<2>{} };
+B b2i = { X<2>{} }; // expected-error {{constructor is explicit}}
+constexpr B b2c { X<2>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
+constexpr B b2ic = { X<2>{} }; // expected-error {{constructor is explicit}}
+
+B b3 { X<3>{} };
+B b3i = { X<3>{} }; // expected-error {{constructor is explicit}}
+constexpr B b3c { X<3>{} };
+constexpr B b3ic = { X<3>{} }; // expected-error {{constructor is explicit}}
+
+
+// 'constexpr' is OK even if the constructor doesn't obey the constraints.
+struct NonLiteral { NonLiteral(); };
+struct NonConstexpr { NonConstexpr(); constexpr NonConstexpr(int); }; // expected-note {{here}}
+struct Constexpr { constexpr Constexpr(int) {} };
+
+struct BothNonLiteral : NonLiteral, Constexpr { using Constexpr::Constexpr; }; // expected-note {{base class 'NonLiteral' of non-literal type}}
+constexpr BothNonLiteral bothNL{42}; // expected-error {{constexpr variable cannot have non-literal type 'const BothNonLiteral'}}
+
+struct BothNonConstexpr : NonConstexpr, Constexpr { using Constexpr::Constexpr; }; // expected-note {{non-constexpr constructor 'NonConstexpr}}
+constexpr BothNonConstexpr bothNC{42}; // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'BothNonConstexpr(42)'}}
+
+
+struct ConstexprEval {
+  constexpr ConstexprEval(int a, const char *p) : k(p[a]) {}
+  char k;
+};
+struct ConstexprEval2 {
+  char k2 = 'x';
+};
+struct ConstexprEval3 : ConstexprEval, ConstexprEval2 {
+  using ConstexprEval::ConstexprEval;
+};
+constexpr ConstexprEval3 ce{4, "foobar"};
+static_assert(ce.k == 'a', "");
+static_assert(ce.k2 == 'x', "");
diff --git a/test/CXX/special/class.inhctor/p3.cpp b/test/CXX/special/class.inhctor/p3.cpp
index d7093fb369..f71ab16c0f 100644
--- a/test/CXX/special/class.inhctor/p3.cpp
+++ b/test/CXX/special/class.inhctor/p3.cpp
@@ -5,7 +5,7 @@ struct B1 {
   B1(int, int);
 };
 struct D1 : B1 {
-  using B1::B1; // expected-error {{not supported}}
+  using B1::B1;
 };
 D1 d1a(1), d1b(1, 1);
 
@@ -15,7 +15,7 @@ struct B2 {
   explicit B2(int, int = 0, int = 0);
 };
 struct D2 : B2 { // expected-note 2 {{candidate constructor}}
-  using B2::B2; // expected-error {{not supported}}
+  using B2::B2;
 };
 D2 d2a(1), d2b(1, 1), d2c(1, 1, 1);
 
@@ -25,18 +25,18 @@ struct B3 {
   B3(void*); // expected-note {{inherited from here}}
 };
 struct D3 : B3 { // expected-note 2 {{candidate constructor}}
-  using B3::B3; // expected-note {{candidate constructor (inherited)}} expected-error {{not supported}}
+  using B3::B3; // expected-note {{candidate constructor (inherited)}}
 };
 D3 fd3() { return 1; } // expected-error {{no viable conversion}}
 
 template<typename T> struct T1 : B1 {
-  using B1::B1; // expected-error {{not supported}}
+  using B1::B1;
 };
 template<typename T> struct T2 : T1<T> {
-  using T1<int>::T1; // expected-error {{not supported}}
+  using T1<int>::T1;
 };
 template<typename T> struct T3 : T1<int> {
-  using T1<T>::T1; // expected-error {{not supported}}
+  using T1<T>::T1;
 };
 struct U {
   friend T1<int>::T1(int);
diff --git a/test/CXX/special/class.inhctor/p4.cpp b/test/CXX/special/class.inhctor/p4.cpp
new file mode 100644
index 0000000000..eea3bf2973
--- /dev/null
+++ b/test/CXX/special/class.inhctor/p4.cpp
@@ -0,0 +1,70 @@
+// RUN: %clang_cc1 -std=c++11 -verify %s
+
+template<int> struct X {};
+
+// A[n inheriting] constructor [...] has the same access as the corresponding
+// constructor [in the base class].
+struct A {
+public:
+  A(X<0>) {}
+protected:
+  A(X<1>) {}
+private:
+  A(X<2>) {} // expected-note {{declared private here}}
+  friend class FA;
+};
+
+struct B : A {
+  using A::A; // expected-error {{private constructor}} expected-note {{implicitly declared protected here}}
+  friend class FB;
+};
+
+B b0{X<0>{}};
+B b1{X<1>{}}; // expected-error {{calling a protected constructor}}
+B b2{X<2>{}}; // expected-note {{first required here}}
+
+struct C : B {
+  C(X<0> x) : B(x) {}
+  C(X<1> x) : B(x) {}
+};
+
+struct FB {
+  B b0{X<0>{}};
+  B b1{X<1>{}};
+};
+
+struct FA : A {
+  using A::A; // expected-note 2{{here}}
+};
+FA fa0{X<0>{}};
+FA fa1{X<1>{}}; // expected-error {{calling a protected constructor}}
+FA fa2{X<2>{}}; // expected-error {{calling a private constructor}}
+
+
+// It is deleted if the corresponding constructor [...] is deleted.
+struct G {
+  G(int) = delete;
+};
+struct H : G {
+  using G::G; // expected-note {{marked deleted here}}
+};
+H h(5); // expected-error {{call to implicitly-deleted function of 'H'}}
+
+
+// Core defect: It is also deleted if multiple base constructors generate the
+// same signature.
+namespace DRnnnn {
+  struct A {
+    constexpr A(int, float = 0) {}
+    explicit A(int, int = 0) {}
+
+    A(int, int, int = 0) = delete;
+  };
+  struct B : A {
+    // FIXME: produce notes indicating why it was deleted
+    using A::A; // expected-note {{here}}
+  };
+
+  constexpr B b0(0, 0.0f); // ok, constexpr
+  B b1(0, 1); // expected-error {{call to implicitly-deleted}}
+}
diff --git a/test/CXX/special/class.inhctor/p7.cpp b/test/CXX/special/class.inhctor/p7.cpp
index bfaa3ac359..9ae160f054 100644
--- a/test/CXX/special/class.inhctor/p7.cpp
+++ b/test/CXX/special/class.inhctor/p7.cpp
@@ -8,12 +8,12 @@ struct B2 {
   B2(int); // expected-note {{conflicting constructor}}
 };
 struct D1 : B1, B2 {
-  using B1::B1; // expected-note {{inherited here}} expected-error {{not supported}}
-  using B2::B2; // expected-error {{already inherited constructor with the same signature}} expected-error {{not supported}}
+  using B1::B1; // expected-note {{inherited here}}
+  using B2::B2; // expected-error {{already inherited constructor with the same signature}}
 };
 struct D2 : B1, B2 {
-  using B1::B1; // expected-error {{not supported}}
-  using B2::B2; // expected-error {{not supported}}
+  using B1::B1;
+  using B2::B2;
   D2(int);
 };
 
@@ -22,8 +22,8 @@ template<typename T> struct B3 {
 };
 template<typename T> struct B4 : B3<T>, B1 {
   B4();
-  using B3<T>::B3; // expected-note {{inherited here}} expected-error {{not supported}}
-  using B1::B1; // expected-error {{already inherited}} expected-error {{not supported}}
+  using B3<T>::B3; // expected-note {{inherited here}}
+  using B1::B1; // expected-error {{already inherited}}
 };
 B4<char> b4c;
 B4<int> b4i; // expected-note {{here}}
diff --git a/test/CXX/special/class.inhctor/p8.cpp b/test/CXX/special/class.inhctor/p8.cpp
new file mode 100644
index 0000000000..e2b07dfae8
--- /dev/null
+++ b/test/CXX/special/class.inhctor/p8.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -std=c++11 -verify %s
+
+// expected-no-diagnostics
+struct A {
+  constexpr A(const int&) : rval(false) {}
+  constexpr A(const int&&) : rval(true) {}
+  bool rval;
+};
+struct B : A {
+  using A::A;
+};
+
+constexpr int k = 0;
+constexpr A a0{0};
+constexpr A a1{k};
+constexpr B b0{0};
+// This performs static_cast<(const int&)&&>(k), so calls the A(const int&)
+// constructor.
+constexpr B b1{k};
+
+static_assert(a0.rval && !a1.rval && b0.rval && !b1.rval, "");