Introduce a representation for types that we referred to via a
qualified name, e.g., 

  foo::x

so that we retain the nested-name-specifier as written in the source
code and can reproduce that qualified name when printing the types
back (e.g., in diagnostics). This is PR3493, which won't be complete
until finished the other tasks mentioned near the end of this commit.

The parser's representation of nested-name-specifiers, CXXScopeSpec,
is now a bit fatter, because it needs to contain the scopes that
precede each '::' and keep track of whether the global scoping
operator '::' was at the beginning. For example, we need to keep track
of the leading '::', 'foo', and 'bar' in
 
  ::foo::bar::x

The Action's CXXScopeTy * is no longer a DeclContext *. It's now the
opaque version of the new NestedNameSpecifier, which contains a single
component of a nested-name-specifier (either a DeclContext * or a Type
*, bitmangled). 

The new sugar type QualifiedNameType composes a sequence of
NestedNameSpecifiers with a representation of the type we're actually
referring to. At present, we only build QualifiedNameType nodes within
Sema::getTypeName. This will be extended to other type-constructing
actions (e.g., ActOnClassTemplateId).

Also on the way: QualifiedDeclRefExprs will also store a sequence of
NestedNameSpecifiers, so that we can print out the property
nested-name-specifier. I expect to also use this for handling
dependent names like Fibonacci<I - 1>::value.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67265 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index bb3df08..b066802 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -96,6 +96,8 @@
   if (const ClassTemplateSpecializationType *Spec 
         = dyn_cast<ClassTemplateSpecializationType>(this))
     return Spec->getCanonicalTypeInternal().getDesugaredType();
+  if (const QualifiedNameType *QualName  = dyn_cast<QualifiedNameType>(this))
+    return QualName->getNamedType().getDesugaredType();
 
   // FIXME: remove this cast.
   return QualType(const_cast<Type*>(this), 0);
@@ -1045,6 +1047,28 @@
     Args[Idx].Profile(ID);
 }
 
+QualifiedNameType::QualifiedNameType(const NestedNameSpecifier *Components,
+                                     unsigned NumComponents, 
+                                     QualType NamedType,
+                                     QualType CanonType)
+  : Type(QualifiedName, CanonType, NamedType->isDependentType()),
+    NumComponents(NumComponents), NamedType(NamedType) {
+  NestedNameSpecifier *InitComponents 
+    = reinterpret_cast<NestedNameSpecifier *>(this + 1);
+  for (unsigned I = 0; I < NumComponents; ++I)
+    new (InitComponents + I) NestedNameSpecifier(Components[I]);
+}
+
+void QualifiedNameType::Profile(llvm::FoldingSetNodeID &ID, 
+                                const NestedNameSpecifier *Components,
+                                unsigned NumComponents, 
+                                QualType NamedType) {
+  ID.AddInteger(NumComponents);
+  for (unsigned I = 0; I < NumComponents; ++I)
+    ID.AddPointer(Components[I].getAsOpaquePtr());
+  NamedType.Profile(ID);
+}
+
 //===----------------------------------------------------------------------===//
 // Type Printing
 //===----------------------------------------------------------------------===//
@@ -1411,6 +1435,38 @@
     InnerString = SpecString + ' ' + InnerString;
 }
 
+void QualifiedNameType::getAsStringInternal(std::string &InnerString) const {
+  std::string MyString;
+
+  for (iterator Comp = begin(), CompEnd = end(); Comp != CompEnd; ++Comp) {
+    if (Type *T = Comp->getAsType()) {
+      std::string TypeStr;
+      if (const TagType *TagT = dyn_cast<TagType>(T))
+        TagT->getAsStringInternal(TypeStr, true);
+      else
+        T->getAsStringInternal(TypeStr);
+
+      MyString += TypeStr;
+    } else if (NamedDecl *NamedDC 
+               = dyn_cast_or_null<NamedDecl>(Comp->getAsDeclContext()))
+      MyString += NamedDC->getNameAsString();
+    MyString += "::";
+  }
+  
+  std::string TypeStr;
+  if (const TagType *TagT = dyn_cast<TagType>(NamedType.getTypePtr())) {
+    // Suppress printing of 'enum', 'struct', 'union', or 'class'.
+    TagT->getAsStringInternal(TypeStr, true);
+  } else
+    NamedType.getAsStringInternal(TypeStr);
+
+  MyString += TypeStr;
+  if (InnerString.empty())
+    InnerString.swap(MyString);
+  else
+    InnerString = MyString + ' ' + InnerString;
+}
+
 void ObjCInterfaceType::getAsStringInternal(std::string &InnerString) const {
   if (!InnerString.empty())    // Prefix the basic type, e.g. 'typedefname X'.
     InnerString = ' ' + InnerString;
@@ -1451,10 +1507,15 @@
 }
 
 void TagType::getAsStringInternal(std::string &InnerString) const {
+  getAsStringInternal(InnerString, false);
+}
+
+void TagType::getAsStringInternal(std::string &InnerString,
+                                  bool SuppressTagKind) const {
   if (!InnerString.empty())    // Prefix the basic type, e.g. 'typedefname X'.
     InnerString = ' ' + InnerString;
   
-  const char *Kind = getDecl()->getKindName();
+  const char *Kind = SuppressTagKind? 0 : getDecl()->getKindName();
   const char *ID;
   if (const IdentifierInfo *II = getDecl()->getIdentifier())
     ID = II->getName();