Clarify that QualifiedNameType is sugar-only. This will matter once we can parse typename-specifiers

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67803 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index e37b186..b05f478 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -1562,7 +1562,9 @@
 /// name, e.g., N::M::type.
 ///
 /// This type is used to keep track of a type name as written in the
-/// source code, including any nested-name-specifiers.
+/// source code, including any nested-name-specifiers. The type itself
+/// is always "sugar", used to express what was written in the source
+/// code but containing no additional semantic information.
 class QualifiedNameType : public Type, public llvm::FoldingSetNode {
   /// \brief The nested name specifier containing the qualifier.
   NestedNameSpecifier *NNS;