3 files changed, 13 insertions, 5 deletions
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index c3cfbb8c25..1835899e80 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -3937,7 +3937,7 @@ static bool CheckNonTypeClassTemplatePartialSpecializationArgs(Sema &S,
       continue;
     }
 
-    // We can have a pack expansion of any of the above.
+    // We can have a pack expansion of any of the bullets below.
     if (PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(ArgExpr))
       ArgExpr = Expansion->getPattern();
     
diff --git a/lib/Sema/SemaTemplateVariadic.cpp b/lib/Sema/SemaTemplateVariadic.cpp
index 828d2a3539..a3e308fe11 100644
--- a/lib/Sema/SemaTemplateVariadic.cpp
+++ b/lib/Sema/SemaTemplateVariadic.cpp
@@ -428,7 +428,8 @@ bool Sema::CheckParameterPacksForExpansion(SourceLocation EllipsisLoc,
     // If we don't have a template argument at this depth/index, then we 
     // cannot expand the pack expansion. Make a note of this, but we still 
     // want to check any parameter packs we *do* have arguments for.
-    if (!TemplateArgs.hasTemplateArgument(Depth, Index)) {
+    if (Depth >= TemplateArgs.getNumLevels() ||
+        !TemplateArgs.hasTemplateArgument(Depth, Index)) {
       ShouldExpand = false;
       continue;
     }
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 9088ae0fef..c38902a3e9 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -2102,11 +2102,18 @@ public:
   TemplateArgumentLoc RebuildPackExpansion(TemplateArgumentLoc Pattern,
                                            SourceLocation EllipsisLoc) {
     switch (Pattern.getArgument().getKind()) {
-    case TemplateArgument::Expression:
-        // FIXME: We should be able to handle this now!
+    case TemplateArgument::Expression: {
+      ExprResult Result
+        = getSema().ActOnPackExpansion(Pattern.getSourceExpression(),
+                                       EllipsisLoc);
+      if (Result.isInvalid())
+        return TemplateArgumentLoc();
+          
+      return TemplateArgumentLoc(Result.get(), Result.get());
+    }
         
     case TemplateArgument::Template:
-      llvm_unreachable("Unsupported pack expansion of expressions/templates");
+      llvm_unreachable("Unsupported pack expansion of templates");
         
     case TemplateArgument::Null:
     case TemplateArgument::Integral: