From 9127029fbbea7b39dcb587ba1118c503d39d1cb0 Mon Sep 17 00:00:00 2001
From: Kenneth Moreland <kmorel@sandia.gov>
Date: Wed, 28 Feb 2018 13:18:45 -0700
Subject: [PATCH] Determine ExecObject type directly from PrepareForExecution

Rather than require all ExecutionObjectFactoryBase classes to declare a
templated ExecObjectType type, get the type of the execution object
directly from the result of the PrepareForExecution method.
---
 vtkm/cont/CellLocatorTwoLevelUniformGrid.h            |  8 +++-----
 vtkm/cont/arg/TransportTagExecObject.h                | 10 ++++------
 vtkm/cont/arg/testing/UnitTestTransportExecObject.cxx |  7 ++-----
 vtkm/exec/arg/FetchTagExecObject.h                    | 10 ----------
 4 files changed, 9 insertions(+), 26 deletions(-)

diff --git a/vtkm/cont/CellLocatorTwoLevelUniformGrid.h b/vtkm/cont/CellLocatorTwoLevelUniformGrid.h
index 1f9490614..35a17bf41 100644
--- a/vtkm/cont/CellLocatorTwoLevelUniformGrid.h
+++ b/vtkm/cont/CellLocatorTwoLevelUniformGrid.h
@@ -613,12 +613,10 @@ public:
   struct TwoLevelUniformGridExecutionObjectFactory : public vtkm::cont::ExecutionObjectFactoryBase
   {
     template <typename DeviceAdapter>
-    using ExecObjectType = TwoLevelUniformGridExecution<DeviceAdapter>;
-
-    template <typename DeviceAdapter>
-    VTKM_CONT ExecObjectType<DeviceAdapter> PrepareForExecution(DeviceAdapter device) const
+    VTKM_CONT TwoLevelUniformGridExecution<DeviceAdapter> PrepareForExecution(
+      DeviceAdapter device) const
     {
-      ExecObjectType<DeviceAdapter> deviceObject;
+      TwoLevelUniformGridExecution<DeviceAdapter> deviceObject;
       deviceObject.TopLevel = this->TopLevel;
       deviceObject.LeafDimensions = this->LeafDimensions.PrepareForInput(device);
       deviceObject.LeafStartIndex = this->LeafStartIndex.PrepareForInput(device);
diff --git a/vtkm/cont/arg/TransportTagExecObject.h b/vtkm/cont/arg/TransportTagExecObject.h
index f60341700..ad9325c80 100644
--- a/vtkm/cont/arg/TransportTagExecObject.h
+++ b/vtkm/cont/arg/TransportTagExecObject.h
@@ -47,16 +47,14 @@ struct TransportTagExecObject
 template <typename ContObjectType, typename Device>
 struct Transport<vtkm::cont::arg::TransportTagExecObject, ContObjectType, Device>
 {
-  // If you get a compile error here, it means you tried to use an object that
-  // is not an execution object as an argument that is expected to be one. All
-  // execution objects are expected to inherit from
-  // vtkm::exec::ExecutionObjectBase.
+  // If you get a compile error here, it means you tried to use an object that is not an execution
+  // object as an argument that is expected to be one. All execution objects are expected to
+  // inherit from vtkm::exec::ExecutionObjectFactoryBase.
   VTKM_STATIC_ASSERT_MSG(
     (std::is_base_of<vtkm::cont::ExecutionObjectFactoryBase, ContObjectType>::value),
     "All execution objects are expected to inherit from vtkm::exec::ExecutionObjectBase");
 
-  //  using ExecObjectType = typename ContObjectType::template ExecObjectType<Device>;
-  using ExecObjectType = typename ContObjectType::template ExecObjectType<Device>;
+  using ExecObjectType = decltype(std::declval<ContObjectType>().PrepareForExecution(Device()));
   template <typename InputDomainType>
   VTKM_CONT ExecObjectType
   operator()(const ContObjectType& object, const InputDomainType&, vtkm::Id, vtkm::Id) const
diff --git a/vtkm/cont/arg/testing/UnitTestTransportExecObject.cxx b/vtkm/cont/arg/testing/UnitTestTransportExecObject.cxx
index bc70a1c26..ead30de79 100644
--- a/vtkm/cont/arg/testing/UnitTestTransportExecObject.cxx
+++ b/vtkm/cont/arg/testing/UnitTestTransportExecObject.cxx
@@ -44,12 +44,9 @@ struct TestExecutionObject : public vtkm::cont::ExecutionObjectFactoryBase
   vtkm::Int32 Number;
 
   template <typename Device>
-  using ExecObjectType = ExecutionObject<Device>;
-
-  template <typename Device>
-  VTKM_CONT ExecObjectType<Device> PrepareForExecution(Device) const
+  VTKM_CONT ExecutionObject<Device> PrepareForExecution(Device) const
   {
-    ExecObjectType<Device> object;
+    ExecutionObject<Device> object;
     object.Number = this->Number;
     return object;
   }
diff --git a/vtkm/exec/arg/FetchTagExecObject.h b/vtkm/exec/arg/FetchTagExecObject.h
index b59ff5c25..8028cee00 100644
--- a/vtkm/exec/arg/FetchTagExecObject.h
+++ b/vtkm/exec/arg/FetchTagExecObject.h
@@ -23,8 +23,6 @@
 #include <vtkm/exec/arg/AspectTagDefault.h>
 #include <vtkm/exec/arg/Fetch.h>
 
-#include <vtkm/cont/ExecutionObjectFactoryBase.h>
-
 #include <type_traits>
 
 namespace vtkm
@@ -51,14 +49,6 @@ struct Fetch<vtkm::exec::arg::FetchTagExecObject,
              ThreadIndicesType,
              ExecObjectType>
 {
-  // If you get a compile error here, it means you tried to use an object that
-  // is not an execution object as an argument that is expected to be one. All
-  // execution objects are expected to inherit from
-  // vtkm::exec::ExecutionObjectFactoryBase.
-  static_assert(
-    std::is_base_of<vtkm::cont::ExecutionObjectFactoryBase, ExecObjectType>::value,
-    "All execution objects are expected to inherit from vtkm::cont::ExecutionObjectFactoryBase");
-
   using ValueType = ExecObjectType;
 
   VTKM_SUPPRESS_EXEC_WARNINGS