Make sure all ArrayPortals have a Set method.

The current design for ArrayPortalVirtual makes it a requirement for all
array portals (that it wraps) to have Set defined. Thus, make sure Set is
defined for all ArrayPortal. Where Set is invalid, an assert is thrown if
something calls it at runtime.

vtkm/cont/ArrayHandleCompositeVector.h

@@ -213,6 +213,17 @@ public:
     return localPortals.GetReturnValue();
   }
 
+  VTKM_SUPPRESS_EXEC_WARNINGS
+  VTKM_EXEC_CONT
+  void Set(vtkm::Id vtkmNotUsed(index),
+           const ValueType &vtkmNotUsed(value)) const
+  {
+    // There is no technical reason why this cannot be implemented. As of this
+    // writing no one has needed to write to a composite vector yet.
+    VTKM_ASSERT(false && "Set not yet implemented for composite vector. Do you volunteer to implement it?");
+  }
+
+
 private:
   PortalTypes Portals;
   ComponentMapType SourceComponents;

vtkm/cont/ArrayHandleCounting.h

@@ -82,6 +82,13 @@ public:
                      this->Step*ValueType(static_cast<ComponentType>(index)));
   }
 
+  VTKM_EXEC_CONT
+  void Set(vtkm::Id vtkmNotUsed(index),
+           const ValueType &vtkmNotUsed(value)) const
+  {
+    VTKM_ASSERT(false && "Cannot write to read-only counting array.");
+  }
+
 private:
   ValueType Start;
   ValueType Step;

vtkm/cont/ArrayHandleImplicit.h

@@ -60,9 +60,17 @@ public:
   VTKM_EXEC_CONT
   vtkm::Id GetNumberOfValues() const { return this->NumberOfValues; }
 
+  VTKM_SUPPRESS_EXEC_WARNINGS
   VTKM_EXEC_CONT
   ValueType Get(vtkm::Id index) const { return this->Functor(index); }
 
+  VTKM_EXEC_CONT
+  void Set(vtkm::Id vtkmNotUsed(index),
+           const ValueType &vtkmNotUsed(value)) const
+  {
+    VTKM_ASSERT(false && "Cannot write to read-only implicit array.");
+  }
+
   typedef vtkm::cont::internal::IteratorFromArrayPortal<
       ArrayPortalImplicit<ValueType,FunctorType> > IteratorType;
 

vtkm/cont/ArrayHandleTransform.h

@@ -88,6 +88,14 @@ public:
     return this->Functor(this->Portal.Get(index));
   }
 
+  VTKM_SUPPRESS_EXEC_WARNINGS
+  VTKM_EXEC_CONT
+  void Set(vtkm::Id vtkmNotUsed(index),
+           const ValueType &vtkmNotUsed(value)) const
+  {
+    VTKM_ASSERT(false && "Cannot write to read-only transform array. (No inverse transform given.)");
+  }
+
   VTKM_SUPPRESS_EXEC_WARNINGS
   VTKM_EXEC_CONT
   const PortalType &GetPortal() const { return this->Portal; }

vtkm/cont/ArrayPortal.h

@@ -72,8 +72,9 @@ public:
   VTKM_CONT
   ValueType Get(vtkm::Id index) const;
 
-  /// Sets a value in the array. This function may not exist for an ArrayPortal
-  /// pointing to a const array.
+  /// Sets a value in the array. If it is not possible to set a value in the
+  /// array, this method may error out (for example with a VTKM_ASSERT). In
+  /// this case the behavior is undefined.
   ///
   VTKM_CONT
   void Set(vtkm::Id index, const ValueType &value) const;

vtkm/cont/cuda/ArrayHandleCuda.h

@@ -87,6 +87,13 @@ public:
       "ArrayHandleCuda only provides access to the device pointer.");
   }
 
+  VTKM_CONT
+  void Set(vtkm::Id vtkmNotUsed(index), T vtkmNotUsed(value)) const
+  {
+    throw vtkm::cont::ErrorControlBadType(
+      "ArrayHandleCuda only provides access to the device pointer.");
+  }
+
   VTKM_CONT
   DevicePointer GetDevicePointer() const
   {

vtkm/cont/internal/ArrayPortalFromIterators.h

@@ -181,6 +181,13 @@ public:
     return *this->IteratorAt(index);
   }
 
+  VTKM_SUPPRESS_EXEC_WARNINGS
+  VTKM_EXEC_CONT
+  void Set(vtkm::Id vtkmNotUsed(index), const ValueType& vtkmNotUsed(value)) const
+  {
+    VTKM_ASSERT(false && "Attempted to write to constant array.");
+  }
+
   VTKM_SUPPRESS_EXEC_WARNINGS
   VTKM_EXEC_CONT
   IteratorT GetIteratorBegin() const {

vtkm/cont/testing/TestingFancyArrayHandles.h

@@ -303,7 +303,7 @@ private:
       {
         vtkm::Id implicitLen = length - start_pos;
         vtkm::Id basicLen    = start_pos;
-    
+
         // make an implicit array
         ValueHandleType implicit =
             vtkm::cont::make_ArrayHandleImplicit<ValueType>(functor,

vtkm/exec/cuda/internal/ArrayPortalFromThrust.h

@@ -346,8 +346,8 @@ public:
 
 
   __host__ __device__
-  void Set(vtkm::Id index, ValueType value) const {
-    *(this->BeginIterator + index) = value;
+  void Set(vtkm::Id vtkmNotUsed(index), ValueType vtkmNotUsed(value)) const {
+     VTKM_ASSERT("Cannot set to const array.");
   }
 
   VTKM_EXEC_CONT