Parsing and AST support for using declarations, from John Thompson!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@73812 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 52 insertions, 4 deletions

diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 230bcffa72..560f952bff 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -1547,6 +1547,14 @@ public:
                                            const CXXScopeSpec &SS,
                                            SourceLocation IdentLoc,
                                            IdentifierInfo *Ident);
+
+  virtual DeclPtrTy ActOnUsingDeclaration(Scope *CurScope,
+                                        SourceLocation UsingLoc,
+                                        const CXXScopeSpec &SS,
+                                        SourceLocation IdentLoc,
+                                        IdentifierInfo *TargetName,
+                                        AttributeList *AttrList,
+                                        bool IsTypeName);
   
   /// AddCXXDirectInitializerToDecl - This action is called immediately after 
   /// ActOnDeclarator, when a C++ direct initializer is present.
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 2dd02af7b9..06fd1a1736 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2284,7 +2284,7 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
       Diag(NewFD->getLocation(), diag::err_out_of_line_declaration)
         << D.getCXXScopeSpec().getRange();
       NewFD->setInvalidDecl();
-    } else if (!Redeclaration) {
+    } else if (!Redeclaration && (!PrevDecl || !isa<UsingDecl>(PrevDecl))) {
       // The user tried to provide an out-of-line definition for a
       // function that is a member of a class or namespace, but there
       // was no such member function declared (C++ [class.mfct]p2, 
@@ -2455,7 +2455,8 @@ void Sema::CheckFunctionDeclaration(FunctionDecl *NewFD, NamedDecl *&PrevDecl,
 
     if (PrevDecl && 
         (!AllowOverloadingOfFunction(PrevDecl, Context) || 
-         !IsOverload(NewFD, PrevDecl, MatchedDecl))) {
+         !IsOverload(NewFD, PrevDecl, MatchedDecl)) &&
+        !isa<UsingDecl>(PrevDecl)) {
       Redeclaration = true;
       Decl *OldDecl = PrevDecl;
 
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 8c547cd1cc..7524cbf500 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -1748,6 +1748,43 @@ void Sema::PushUsingDirective(Scope *S, UsingDirectiveDecl *UDir) {
     S->PushUsingDirective(DeclPtrTy::make(UDir));
 }
 
+
+Sema::DeclPtrTy Sema::ActOnUsingDeclaration(Scope *S,
+                                          SourceLocation UsingLoc,
+                                          const CXXScopeSpec &SS,
+                                          SourceLocation IdentLoc,
+                                          IdentifierInfo *TargetName,
+                                          AttributeList *AttrList,
+                                          bool IsTypeName) {
+  assert(!SS.isInvalid() && "Invalid CXXScopeSpec.");
+  assert(TargetName && "Invalid TargetName.");
+  assert(IdentLoc.isValid() && "Invalid TargetName location.");
+  assert(S->getFlags() & Scope::DeclScope && "Invalid Scope.");
+
+  UsingDecl *UsingAlias = 0;
+
+  // Lookup target name.
+  LookupResult R = LookupParsedName(S, &SS, TargetName,
+                                    LookupOrdinaryName, false);
+
+  if (NamedDecl *NS = R) {
+    if (IsTypeName && !isa<TypeDecl>(NS)) {
+      Diag(IdentLoc, diag::err_using_typename_non_type);
+    }
+    UsingAlias = UsingDecl::Create(Context, CurContext, IdentLoc, SS.getRange(),
+        NS->getLocation(), UsingLoc, NS,
+        static_cast<NestedNameSpecifier *>(SS.getScopeRep()),
+        IsTypeName);
+    PushOnScopeChains(UsingAlias, S);
+  } else {
+    Diag(IdentLoc, diag::err_using_requires_qualname) << SS.getRange();
+  }
+
+  // FIXME: We ignore attributes for now.
+  delete AttrList;
+  return DeclPtrTy::make(UsingAlias);
+}
+
 /// getNamespaceDecl - Returns the namespace a decl represents. If the decl
 /// is a namespace alias, returns the namespace it points to.
 static inline NamespaceDecl *getNamespaceDecl(NamedDecl *D) {
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 52de4e6f4c..37e1df3a19 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -1151,8 +1151,10 @@ Sema::LookupParsedName(Scope *S, const CXXScopeSpec *SS,
                                Name, NameKind, RedeclarationOnly);
   }
 
-  return LookupName(S, Name, NameKind, RedeclarationOnly, 
-                    AllowBuiltinCreation, Loc);
+  LookupResult result(LookupName(S, Name, NameKind, RedeclarationOnly, 
+                    AllowBuiltinCreation, Loc));
+  
+  return(result);
 }