Fixes for Kokkos::Array (kokkos#6372)

* WIP: Adding unit tests for Kokkos::Array

* Remove ScopedEnum tests (as they don't compile)

* Fix for empty() bug with contiguous and strided Kokkos::Array

* Fixed strided Kokkos::Array assignment operators

* Clean up unit tests

* Fix for char subscript warning during Kokkos::Array unit tests

* Changed Kokkos::Array<T, 0>::data() to return nullptr instead of
pointer(0), as this eliminates some compiler warnings

* Fixes for __int128 and CUDA-11.0.3 build

* Removed tests for __int128

* Fixed ch (which should be c8) for char8_t indexing tests

* Removed char and *char_t tests
(left unsigned char and signed char, as uint8_t and int8_t are
sometimes aliases for them)
Changed EnumBool to EnumShort as it is slightly more realistic

core/src/Kokkos_Array.hpp

@@ -163,8 +163,8 @@ struct Array<T, 0, Proxy> {
     return *reinterpret_cast<const_pointer>(-1);
   }
 
-  KOKKOS_INLINE_FUNCTION pointer data() { return pointer(0); }
-  KOKKOS_INLINE_FUNCTION const_pointer data() const { return const_pointer(0); }
+  KOKKOS_INLINE_FUNCTION pointer data() { return nullptr; }
+  KOKKOS_INLINE_FUNCTION const_pointer data() const { return nullptr; }
 
   KOKKOS_DEFAULTED_FUNCTION ~Array()            = default;
   KOKKOS_DEFAULTED_FUNCTION Array()             = default;
@@ -199,7 +199,7 @@ struct Array<T, KOKKOS_INVALID_INDEX, Array<>::contiguous> {
   using const_pointer   = std::add_const_t<T>*;
 
   KOKKOS_INLINE_FUNCTION constexpr size_type size() const { return m_size; }
-  KOKKOS_INLINE_FUNCTION constexpr bool empty() const { return 0 != m_size; }
+  KOKKOS_INLINE_FUNCTION constexpr bool empty() const { return 0 == m_size; }
   KOKKOS_INLINE_FUNCTION constexpr size_type max_size() const { return m_size; }
 
   template <typename iType>
@@ -268,7 +268,7 @@ struct Array<T, KOKKOS_INVALID_INDEX, Array<>::strided> {
   using const_pointer   = std::add_const_t<T>*;
 
   KOKKOS_INLINE_FUNCTION constexpr size_type size() const { return m_size; }
-  KOKKOS_INLINE_FUNCTION constexpr bool empty() const { return 0 != m_size; }
+  KOKKOS_INLINE_FUNCTION constexpr bool empty() const { return 0 == m_size; }
   KOKKOS_INLINE_FUNCTION constexpr size_type max_size() const { return m_size; }
 
   template <typename iType>
@@ -304,14 +304,14 @@ struct Array<T, KOKKOS_INVALID_INDEX, Array<>::strided> {
   KOKKOS_INLINE_FUNCTION
   Array& operator=(const Array& rhs) {
     const size_t n = std::min(m_size, rhs.size());
-    for (size_t i = 0; i < n; ++i) m_elem[i] = rhs[i];
+    for (size_t i = 0; i < n; ++i) m_elem[i * m_stride] = rhs[i];
     return *this;
   }
 
   template <size_t N, class P>
   KOKKOS_INLINE_FUNCTION Array& operator=(const Array<T, N, P>& rhs) {
     const size_t n = std::min(m_size, rhs.size());
-    for (size_t i = 0; i < n; ++i) m_elem[i] = rhs[i];
+    for (size_t i = 0; i < n; ++i) m_elem[i * m_stride] = rhs[i];
     return *this;
   }
 

core/unit_test/CMakeLists.txt

@@ -120,6 +120,7 @@ foreach(Tag Threads;Serial;OpenMP;Cuda;HPX;OpenMPTarget;OpenACC;HIP;SYCL)
     set(${Tag}_SOURCES1A)
     foreach(Name
         Abort
+        ArrayOps
         AtomicOperations_complexdouble
         AtomicOperations_complexfloat
         AtomicOperations_double