P0217R3: Perform semantic checks and initialization for the bindings in a

decomposition declaration for arrays, aggregate-like structs, tuple-like
types, and (as an extension) for complex and vector types.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@278435 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 81 insertions, 11 deletions

diff --git a/include/clang/AST/CXXInheritance.h b/include/clang/AST/CXXInheritance.h
index 50424a9661..3cf058f26b 100644
--- a/include/clang/AST/CXXInheritance.h
+++ b/include/clang/AST/CXXInheritance.h
@@ -172,7 +172,7 @@ public:
   /// paths for a derived-to-base search.
   explicit CXXBasePaths(bool FindAmbiguities = true, bool RecordPaths = true,
                         bool DetectVirtual = true)
-      : FindAmbiguities(FindAmbiguities), RecordPaths(RecordPaths),
+      : Origin(), FindAmbiguities(FindAmbiguities), RecordPaths(RecordPaths),
         DetectVirtual(DetectVirtual), DetectedVirtual(nullptr),
         NumDeclsFound(0) {}
 
diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 90c854535e..254f575782 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -251,7 +251,7 @@ public:
   // FIXME: Deprecated, move clients to getName().
   std::string getNameAsString() const { return Name.getAsString(); }
 
-  void printName(raw_ostream &os) const { os << Name; }
+  virtual void printName(raw_ostream &os) const;
 
   /// getDeclName - Get the actual, stored name of the declaration,
   /// which may be a special name.
@@ -1025,7 +1025,7 @@ public:
   ///   void foo() { int x; static int y; extern int z; }
   ///
   bool isLocalVarDecl() const {
-    if (getKind() != Decl::Var)
+    if (getKind() != Decl::Var && getKind() != Decl::Decomposition)
       return false;
     if (const DeclContext *DC = getLexicalDeclContext())
       return DC->getRedeclContext()->isFunctionOrMethod();
@@ -1040,7 +1040,7 @@ public:
   /// isFunctionOrMethodVarDecl - Similar to isLocalVarDecl, but
   /// excludes variables declared in blocks.
   bool isFunctionOrMethodVarDecl() const {
-    if (getKind() != Decl::Var)
+    if (getKind() != Decl::Var && getKind() != Decl::Decomposition)
       return false;
     const DeclContext *DC = getLexicalDeclContext()->getRedeclContext();
     return DC->isFunctionOrMethod() && DC->getDeclKind() != Decl::Block;
diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 6a2fcddfd7..48ada29bb6 100644
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -1147,6 +1147,12 @@ public:
   /// \note This does NOT include a check for union-ness.
   bool isEmpty() const { return data().Empty; }
 
+  /// \brief Determine whether this class has direct non-static data members.
+  bool hasDirectFields() const {
+    auto &D = data();
+    return D.HasPublicFields || D.HasProtectedFields || D.HasPrivateFields;
+  }
+
   /// Whether this class is polymorphic (C++ [class.virtual]),
   /// which means that the class contains or inherits a virtual function.
   bool isPolymorphic() const { return data().Polymorphic; }
@@ -3451,6 +3457,8 @@ public:
     return llvm::makeArrayRef(getTrailingObjects<BindingDecl *>(), NumBindings);
   }
 
+  void printName(raw_ostream &os) const override;
+
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == Decomposition; }
 
diff --git a/include/clang/AST/UnresolvedSet.h b/include/clang/AST/UnresolvedSet.h
index 7b4b4e5ccb..868c5a6e19 100644
--- a/include/clang/AST/UnresolvedSet.h
+++ b/include/clang/AST/UnresolvedSet.h
@@ -38,7 +38,7 @@ class UnresolvedSetIterator : public llvm::iterator_adaptor_base<
       : iterator_adaptor_base(const_cast<DeclAccessPair *>(Iter)) {}
 
 public:
-  UnresolvedSetIterator() {}
+  UnresolvedSetIterator() = default;
 
   NamedDecl *getDecl() const { return I->getDecl(); }
   void setDecl(NamedDecl *ND) const { return I->setDecl(ND); }
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 81a47255bf..e7647f80f6 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -385,6 +385,40 @@ def err_decomp_decl_template : Error<
   "decomposition declaration template not supported">;
 def err_decomp_decl_not_alone : Error<
   "decomposition declaration must be the only declaration in its group">;
+def err_decomp_decl_requires_init : Error<
+  "decomposition declaration %0 requires an initializer">;
+def err_decomp_decl_paren_init : Error<
+  "decomposition declaration %0 cannot have a parenthesized initializer">;
+def err_decomp_decl_wrong_number_bindings : Error<
+  "type %0 decomposes into %2 elements, but %select{only |}3%1 "
+  "names were provided">;
+def err_decomp_decl_unbindable_type : Error<
+  "cannot decompose %select{union|non-class, non-array}1 type %2">;
+def err_decomp_decl_multiple_bases_with_members : Error<
+  "cannot decompose class type %1: "
+  "%select{its base classes %2 and|both it and its base class}0 %3 "
+  "have non-static data members">;
+def err_decomp_decl_ambiguous_base : Error<
+  "cannot decompose members of ambiguous base class %1 of %0:%2">;
+def err_decomp_decl_non_public_base : Error<
+  "cannot decompose members of non-public base class %1 of %0">;
+def err_decomp_decl_non_public_member : Error<
+  "cannot decompose non-public member %0 of %1">;
+def err_decomp_decl_anon_union_member : Error<
+  "cannot decompose class type %1 because it has an anonymous "
+  "%select{struct|union} member">;
+def err_decomp_decl_std_tuple_element_not_specialized : Error<
+  "cannot decompose this type; 'std::tuple_element<%0>::type' "
+  "does not name a type">;
+def err_decomp_decl_std_tuple_size_not_constant : Error<
+  "cannot decompose this type; 'std::tuple_size<%0>::value' "
+  "is not a valid integral constant expression">;
+def note_in_binding_decl_init : Note<
+  "in implicit initialization of binding declaration %0">;
+
+def err_std_type_trait_not_class_template : Error<
+  "unsupported standard library implementation: "
+  "'std::%0' is not a class template">;
 
 // C++ using declarations
 def err_using_requires_qualname : Error<
diff --git a/include/clang/Sema/Initialization.h b/include/clang/Sema/Initialization.h
index cf636966d8..e160e3ecc6 100644
--- a/include/clang/Sema/Initialization.h
+++ b/include/clang/Sema/Initialization.h
@@ -84,7 +84,10 @@ public:
     EK_RelatedResult,
     /// \brief The entity being initialized is a function parameter; function
     /// is member of group of audited CF APIs.
-    EK_Parameter_CF_Audited
+    EK_Parameter_CF_Audited,
+    /// \brief The entity being initialized is a structured binding of a
+    /// decomposition declaration.
+    EK_Binding,
 
     // Note: err_init_conversion_failed in DiagnosticSemaKinds.td uses this
     // enum as an index for its first %select.  When modifying this list,
@@ -126,9 +129,9 @@ private:
   };
 
   union {
-    /// \brief When Kind == EK_Variable, or EK_Member, the VarDecl or
-    /// FieldDecl, respectively.
-    DeclaratorDecl *VariableOrMember;
+    /// \brief When Kind == EK_Variable, EK_Member or EK_Binding, the VarDecl,
+    /// FieldDecl or BindingDecl, respectively.
+    ValueDecl *VariableOrMember;
     
     /// \brief When Kind == EK_RelatedResult, the ObjectiveC method where
     /// result type was implicitly changed to accommodate ARC semantics.
@@ -180,6 +183,12 @@ private:
     : Kind(EK_Member), Parent(Parent), Type(Member->getType()),
       ManglingNumber(0), VariableOrMember(Member) { }
   
+  /// \brief Create the initialization entity for a binding.
+  InitializedEntity(BindingDecl *Binding, QualType Type,
+                    const InitializedEntity &Parent)
+    : Kind(EK_Binding), Parent(&Parent), Type(Type),
+      ManglingNumber(0), VariableOrMember(Binding) {}
+
   /// \brief Create the initialization entity for an array element.
   InitializedEntity(ASTContext &Context, unsigned Index, 
                     const InitializedEntity &Parent);
@@ -314,6 +323,13 @@ public:
     return InitializedEntity(Context, Index, Parent);
   }
 
+  /// \brief Create the initialization entity for a structured binding.
+  static InitializedEntity InitializeBinding(const InitializedEntity &Parent,
+                                             BindingDecl *Binding,
+                                             QualType Type) {
+    return InitializedEntity(Binding, Type, Parent);
+  }
+
   /// \brief Create the initialization entity for a lambda capture.
   static InitializedEntity InitializeLambdaCapture(IdentifierInfo *VarID,
                                                    QualType FieldType,
@@ -355,7 +371,7 @@ public:
 
   /// \brief Retrieve the variable, parameter, or field being
   /// initialized.
-  DeclaratorDecl *getDecl() const;
+  ValueDecl *getDecl() const;
   
   /// \brief Retrieve the ObjectiveC method being initialized.
   ObjCMethodDecl *getMethodDecl() const { return MethodDecl; }
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index e92a35f819..04f8b4b002 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -1728,7 +1728,9 @@ public:
   // Returns true if the variable declaration is a redeclaration
   bool CheckVariableDeclaration(VarDecl *NewVD, LookupResult &Previous);
   void CheckVariableDeclarationType(VarDecl *NewVD);
-  void CheckCompleteVariableDeclaration(VarDecl *var);
+  void CheckCompleteVariableDeclaration(VarDecl *VD, InitializedEntity &Entity);
+  void CheckCompleteDecompositionDeclaration(DecompositionDecl *DD,
+                                             InitializedEntity &Entity);
   void MaybeSuggestAddingStaticToDecl(const FunctionDecl *D);
 
   NamedDecl* ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
@@ -3970,6 +3972,12 @@ public:
                            bool SuppressQualifierCheck = false,
                            ActOnMemberAccessExtraArgs *ExtraArgs = nullptr);
 
+  ExprResult BuildFieldReferenceExpr(Expr *BaseExpr, bool IsArrow,
+                                     SourceLocation OpLoc,
+                                     const CXXScopeSpec &SS, FieldDecl *Field,
+                                     DeclAccessPair FoundDecl,
+                                     const DeclarationNameInfo &MemberNameInfo);
+
   ExprResult PerformMemberExprBaseConversion(Expr *Base, bool IsArrow);
 
   bool CheckQualifiedMemberReference(Expr *BaseExpr, QualType BaseType,
@@ -5772,6 +5780,10 @@ public:
                             TemplateParameterList **OuterTemplateParamLists,
                                 SkipBodyInfo *SkipBody = nullptr);
 
+  TemplateArgumentLoc getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
+                                                    QualType NTTPType,
+                                                    SourceLocation Loc);
+
   void translateTemplateArguments(const ASTTemplateArgsPtr &In,
                                   TemplateArgumentListInfo &Out);