From 7ff1a690def7a61fc26a6d2856baf61ca19a9c60 Mon Sep 17 00:00:00 2001
From: Kenneth Moreland <kmorel@sandia.gov>
Date: Mon, 23 Nov 2020 17:17:31 -0700
Subject: [PATCH] Support ArrayHandleCompositeVector with 1 component

When `ArrayHandleCompositeVector` has only 1 component, it is supposed
to have a special template that uses the base value type rather than a
`Vec` of that type. However, the `Storage` with the value type was
missing. I'm not sure how we weren't getting compile errors before, but
moving to the new buffer arrays seems to bring about the expected error.
---
 vtkm/cont/ArrayHandleCompositeVector.h | 21 +++++++++++++++++++--
 vtkm/cont/Storage.h                    |  4 ++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/vtkm/cont/ArrayHandleCompositeVector.h b/vtkm/cont/ArrayHandleCompositeVector.h
index e38960aab..c3e1341cd 100644
--- a/vtkm/cont/ArrayHandleCompositeVector.h
+++ b/vtkm/cont/ArrayHandleCompositeVector.h
@@ -248,8 +248,8 @@ class Storage<vtkm::Vec<T, static_cast<vtkm::IdComponent>(sizeof...(StorageTags)
 public:
   using ReadPortalType =
     vtkm::internal::ArrayPortalCompositeVector<typename StorageFor<StorageTags>::ReadPortalType...>;
-  using WritePortalType =
-    vtkm::internal::ArrayPortalCompositeVector<typename StorageFor<StorageTags>::ReadPortalType...>;
+  using WritePortalType = vtkm::internal::ArrayPortalCompositeVector<
+    typename StorageFor<StorageTags>::WritePortalType...>;
 
 private:
   // Hoop to jump through to use Storage::ResizeBuffer in an initializer list.
@@ -382,6 +382,23 @@ public:
   }
 };
 
+// Special degenerative case when there is only one array being composited
+template <typename T, typename StorageTag>
+struct Storage<T, vtkm::cont::StorageTagCompositeVec<StorageTag>> : Storage<T, StorageTag>
+{
+  VTKM_CONT static std::vector<vtkm::cont::internal::Buffer> CreateBuffers(
+    const vtkm::cont::ArrayHandle<T, StorageTag>& array)
+  {
+    return vtkm::cont::internal::CreateBuffers(array);
+  }
+
+  VTKM_CONT static vtkm::Tuple<vtkm::cont::ArrayHandle<T, StorageTag>> GetArrayTuple(
+    const vtkm::cont::internal::Buffer* buffers)
+  {
+    return vtkm::cont::ArrayHandle<T, StorageTag>(buffers);
+  }
+};
+
 } // namespace internal
 
 template <typename T, typename... Ss>
diff --git a/vtkm/cont/Storage.h b/vtkm/cont/Storage.h
index a57dcf6a8..11e1c9a33 100644
--- a/vtkm/cont/Storage.h
+++ b/vtkm/cont/Storage.h
@@ -94,8 +94,12 @@ class Storage
   : public vtkm::cont::internal::UndefinedStorage
 {
 public:
+  // TODO: Deprecate these
   using PortalType = vtkm::cont::internal::detail::UndefinedArrayPortal<T>;
   using PortalConstType = vtkm::cont::internal::detail::UndefinedArrayPortal<T>;
+
+  using ReadPortalType = vtkm::cont::internal::detail::UndefinedArrayPortal<T>;
+  using WritePortalType = vtkm::cont::internal::detail::UndefinedArrayPortal<T>;
 };
 #else  //VTKM_DOXYGEN_ONLY
 {