Introduce a new expression type, UnresolvedDeclRefExpr, that describes

dependent qualified-ids such as

  Fibonacci<N - 1>::value

where N is a template parameter. These references are "unresolved"
because the name is dependent and, therefore, cannot be resolved to a
declaration node (as we would do for a DeclRefExpr or
QualifiedDeclRefExpr). UnresolvedDeclRefExprs instantiate to
DeclRefExprs, QualifiedDeclRefExprs, etc.

Also, be a bit more careful about keeping only a single set of
specializations for a class template, and instantiating from the
definition of that template rather than a previous declaration. In
general, we need a better solution for this for all TagDecls, because
it's too easy to accidentally look at a declaration that isn't the
definition.

We can now process a simple Fibonacci computation described as a
template metaprogram.

llvm-svn: 67308

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaCXXScopeSpec.cpp b/clang/lib/Sema/SemaCXXScopeSpec.cpp
index 156f3a12fbb..9e1196143b6 100644
--- a/clang/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/clang/lib/Sema/SemaCXXScopeSpec.cpp
@@ -29,6 +29,21 @@ DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS) {
   return NNS.computeDeclContext(Context);
 }
 
+bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
+  if (!SS.isSet() || SS.isInvalid())
+    return false;
+
+  NestedNameSpecifier NNS
+    = NestedNameSpecifier::getFromOpaquePtr(SS.getCurrentScopeRep());
+
+  if (Type *T = NNS.getAsType())
+    return T->isDependentType();
+
+  // FIXME: What about the injected-class-name of a class template? It
+  // is dependent, but we represent it as a declaration.
+  return false;
+}
+
 /// \brief Require that the context specified by SS be complete.
 ///
 /// If SS refers to a type, this routine checks whether the type is