make fixed_size matrices conform to std::is_standard_layout
diff --git a/Eigen/src/Core/DenseStorage.h b/Eigen/src/Core/DenseStorage.h
index 90bc94e..d62586c 100644
--- a/Eigen/src/Core/DenseStorage.h
+++ b/Eigen/src/Core/DenseStorage.h
@@ -30,10 +30,10 @@
 #if defined(EIGEN_DISABLE_UNALIGNED_ARRAY_ASSERT)
 #define EIGEN_MAKE_UNALIGNED_ARRAY_ASSERT(Alignment)
 #else
-#define EIGEN_MAKE_UNALIGNED_ARRAY_ASSERT(Alignment)                                              \
-  eigen_assert((internal::is_constant_evaluated() || (std::uintptr_t(array) % Alignment == 0)) && \
-               "this assertion is explained here: "                                               \
-               "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html"       \
+#define EIGEN_MAKE_UNALIGNED_ARRAY_ASSERT(Alignment)                                        \
+  eigen_assert((is_constant_evaluated() || (std::uintptr_t(array) % Alignment == 0)) &&     \
+               "this assertion is explained here: "                                         \
+               "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html" \
                " **** READ THIS WEB PAGE !!! ****");
 #endif
 
@@ -48,6 +48,7 @@
  * Static array. If the MatrixOrArrayOptions require auto-alignment, the array will be automatically aligned:
  * to 16 bytes boundary if the total size is a multiple of 16 bytes.
  */
+
 template <typename T, int Size, int MatrixOrArrayOptions,
           int Alignment = (MatrixOrArrayOptions & DontAlign) ? 0 : compute_default_alignment<T, Size>::value>
 struct plain_array {
@@ -78,92 +79,454 @@
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr plain_array() = default;
 };
 
-// this class is intended to be inherited by DenseStorage to take advantage of empty base optimization
-template <int Rows, int Cols>
-struct DenseStorageIndices {
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices() = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(Index /*rows*/, Index /*cols*/) {}
+template <typename T, int Size, int Options, int Alignment>
+EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap_plain_array(plain_array<T, Size, Options, Alignment>& a,
+                                                                      plain_array<T, Size, Options, Alignment>& b,
+                                                                      Index a_size, Index b_size) {
+  Index common_size = numext::mini(a_size, b_size);
+  std::swap_ranges(a.array, a.array + common_size, b.array);
+  if (a_size > b_size)
+    smart_copy(a.array + common_size, a.array + a_size, b.array + common_size);
+  else if (b_size > a_size)
+    smart_copy(b.array + common_size, b.array + b_size, a.array + common_size);
+}
+
+template <typename T, int Size, int Rows, int Cols, int Options>
+class DenseStorage_impl {
+  plain_array<T, Size, Options> m_data;
+
+ public:
+#ifndef EIGEN_DENSE_STORAGE_CTOR_PLUGIN
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl&) = default;
+#else
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = Size)
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl& other) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = Size)
+    smart_copy(other.m_data.array, other.m_data.array + Size, m_data.array);
+  }
+#endif
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index /*size*/, Index /*rows*/, Index /*cols*/) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) {
+    numext::swap(m_data, other.m_data);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index /*rows*/,
+                                                                          Index /*cols*/) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index /*rows*/, Index /*cols*/) {}
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return Rows; }
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return Cols; }
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return Rows * Cols; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void set(Index /*rows*/, Index /*cols*/) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void swap(DenseStorageIndices& /*other*/) noexcept {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data.array; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data.array; }
 };
-template <int Rows>
-struct DenseStorageIndices<Rows, Dynamic> {
-  Index m_cols;
+template <typename T, int Size, int Cols, int Options>
+class DenseStorage_impl<T, Size, Dynamic, Cols, Options> {
+  plain_array<T, Size, Options> m_data;
+  Index m_rows = 0;
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices() : m_cols(0) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(Index /*rows*/, Index cols) : m_cols(cols) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return Rows; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return Rows * m_cols; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void set(Index /*rows*/, Index cols) { m_cols = cols; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void swap(DenseStorageIndices& other) noexcept {
-    numext::swap(m_cols, other.m_cols);
+ public:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl& other)
+      : m_rows(other.m_rows) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = other.size())
+    smart_copy(other.m_data.array, other.m_data.array + other.size(), m_data.array);
   }
-};
-template <int Cols>
-struct DenseStorageIndices<Dynamic, Cols> {
-  Index m_rows;
-
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices() : m_rows(0) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(Index rows, Index /*cols*/) : m_rows(rows) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index size, Index rows, Index /*cols*/)
+      : m_rows(rows) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+    EIGEN_UNUSED_VARIABLE(size)
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl& other) {
+    smart_copy(other.m_data.array, other.m_data.array + other.size(), m_data.array);
+    m_rows = other.m_rows;
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) {
+    swap_plain_array(m_data, other.m_data, size(), other.size());
+    numext::swap(m_rows, other.m_rows);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index rows, Index /*cols*/) {
+    m_rows = rows;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index rows, Index /*cols*/) {
+    m_rows = rows;
+  }
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return m_rows; }
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return Cols; }
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return m_rows * Cols; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void set(Index rows, Index /*cols*/) { m_rows = rows; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void swap(DenseStorageIndices& other) noexcept {
-    numext::swap(m_rows, other.m_rows);
-  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data.array; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data.array; }
 };
-template <>
-struct DenseStorageIndices<Dynamic, Dynamic> {
-  Index m_rows;
-  Index m_cols;
+template <typename T, int Size, int Rows, int Options>
+class DenseStorage_impl<T, Size, Rows, Dynamic, Options> {
+  plain_array<T, Size, Options> m_data;
+  Index m_cols = 0;
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices() : m_rows(0), m_cols(0) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(const DenseStorageIndices&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices& operator=(DenseStorageIndices&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorageIndices(Index rows, Index cols)
-      : m_rows(rows), m_cols(cols) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return m_rows; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return m_rows * m_cols; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void set(Index rows, Index cols) {
-    m_rows = rows;
+ public:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl& other)
+      : m_cols(other.m_cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = other.size())
+    smart_copy(other.m_data.array, other.m_data.array + other.size(), m_data.array);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index size, Index /*rows*/, Index cols)
+      : m_cols(cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+    EIGEN_UNUSED_VARIABLE(size)
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl& other) {
+    smart_copy(other.m_data.array, other.m_data.array + other.size(), m_data.array);
+    m_cols = other.m_cols;
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) {
+    swap_plain_array(m_data, other.m_data, size(), other.size());
+    numext::swap(m_cols, other.m_cols);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index /*rows*/, Index cols) {
     m_cols = cols;
   }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void swap(DenseStorageIndices& other) noexcept {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index /*rows*/, Index cols) {
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return Rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return Rows * m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data.array; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data.array; }
+};
+template <typename T, int Size, int Options>
+class DenseStorage_impl<T, Size, Dynamic, Dynamic, Options> {
+  plain_array<T, Size, Options> m_data;
+  Index m_rows = 0;
+  Index m_cols = 0;
+
+ public:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl& other)
+      : m_rows(other.m_rows), m_cols(other.m_cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = other.size())
+    smart_copy(other.m_data.array, other.m_data.array + other.size(), m_data.array);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index size, Index rows, Index cols)
+      : m_rows(rows), m_cols(cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+    EIGEN_UNUSED_VARIABLE(size)
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl& other) {
+    smart_copy(other.m_data.array, other.m_data.array + other.size(), m_data.array);
+    m_rows = other.m_rows;
+    m_cols = other.m_cols;
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) {
+    swap_plain_array(m_data, other.m_data, size(), other.size());
     numext::swap(m_rows, other.m_rows);
     numext::swap(m_cols, other.m_cols);
   }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index rows, Index cols) {
+    m_rows = rows;
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index rows, Index cols) {
+    m_rows = rows;
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return m_rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return m_rows * m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data.array; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data.array; }
 };
-
-template <int Size, int Rows, int Cols>
-struct use_trivial_ctors {
-  static constexpr bool value = (Size >= 0) && (Rows >= 0) && (Cols >= 0) && (Size == Rows * Cols);
+// null matrix variants
+template <typename T, int Rows, int Cols, int Options>
+class DenseStorage_impl<T, 0, Rows, Cols, Options> {
+ public:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index /*size*/, Index /*rows*/, Index /*cols*/) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl&) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index /*rows*/,
+                                                                          Index /*cols*/) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index /*rows*/, Index /*cols*/) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return Rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return Cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return Rows * Cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return nullptr; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return nullptr; }
 };
+template <typename T, int Cols, int Options>
+class DenseStorage_impl<T, 0, Dynamic, Cols, Options> {
+  Index m_rows = 0;
 
+ public:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index /*size*/, Index rows, Index /*cols*/)
+      : m_rows(rows) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) noexcept {
+    numext::swap(m_rows, other.m_rows);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index rows, Index /*cols*/) {
+    m_rows = rows;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index rows, Index /*cols*/) {
+    m_rows = rows;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return m_rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return Cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return m_rows * Cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return nullptr; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return nullptr; }
+};
+template <typename T, int Rows, int Options>
+class DenseStorage_impl<T, 0, Rows, Dynamic, Options> {
+  Index m_cols = 0;
+
+ public:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index /*size*/, Index /*rows*/, Index cols)
+      : m_cols(cols) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) noexcept {
+    numext::swap(m_cols, other.m_cols);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index /*rows*/, Index cols) {
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index /*rows*/, Index cols) {
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return Rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return Rows * m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return nullptr; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return nullptr; }
+};
+template <typename T, int Options>
+class DenseStorage_impl<T, 0, Dynamic, Dynamic, Options> {
+  Index m_rows = 0;
+  Index m_cols = 0;
+
+ public:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index /*size*/, Index rows, Index cols)
+      : m_rows(rows), m_cols(cols) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) noexcept {
+    numext::swap(m_rows, other.m_rows);
+    numext::swap(m_cols, other.m_cols);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index rows, Index cols) {
+    m_rows = rows;
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index rows, Index cols) {
+    m_rows = rows;
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return m_rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return m_rows * m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return nullptr; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return nullptr; }
+};
+// fixed-size matrix with dynamic memory allocation not currently supported
+template <typename T, int Rows, int Cols, int Options>
+class DenseStorage_impl<T, Dynamic, Rows, Cols, Options> {};
+// dynamic-sized variants
+template <typename T, int Cols, int Options>
+class DenseStorage_impl<T, Dynamic, Dynamic, Cols, Options> {
+  static constexpr bool Align = (Options & DontAlign) == 0;
+  T* m_data = nullptr;
+  Index m_rows = 0;
+
+ public:
+  static constexpr int Size = Dynamic;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl& other)
+      : m_data(conditional_aligned_new_auto<T, Align>(other.size())), m_rows(other.m_rows) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = other.size())
+    smart_copy(other.m_data, other.m_data + other.size(), m_data);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index size, Index rows, Index /*cols*/)
+      : m_data(conditional_aligned_new_auto<T, Align>(size)), m_rows(rows) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(DenseStorage_impl&& other) noexcept
+      : m_data(other.m_data), m_rows(other.m_rows) {
+    other.m_data = nullptr;
+    other.m_rows = 0;
+  }
+  EIGEN_DEVICE_FUNC ~DenseStorage_impl() { conditional_aligned_delete_auto<T, Align>(m_data, size()); }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl& other) {
+    resize(other.size(), other.rows(), other.cols());
+    smart_copy(other.m_data, other.m_data + other.size(), m_data);
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(DenseStorage_impl&& other) noexcept {
+    this->swap(other);
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) noexcept {
+    numext::swap(m_data, other.m_data);
+    numext::swap(m_rows, other.m_rows);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index size, Index rows, Index /*cols*/) {
+    m_data = conditional_aligned_realloc_new_auto<T, Align>(m_data, size, this->size());
+    m_rows = rows;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index size, Index rows, Index /*cols*/) {
+    Index oldSize = this->size();
+    if (oldSize != size) {
+      conditional_aligned_delete_auto<T, Align>(m_data, oldSize);
+      m_data = conditional_aligned_new_auto<T, Align>(size);
+      EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+    }
+    m_rows = rows;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return m_rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return Cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return m_rows * Cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data; }
+};
+template <typename T, int Rows, int Options>
+class DenseStorage_impl<T, Dynamic, Rows, Dynamic, Options> {
+  static constexpr bool Align = (Options & DontAlign) == 0;
+  T* m_data = nullptr;
+  Index m_cols = 0;
+
+ public:
+  static constexpr int Size = Dynamic;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl& other)
+      : m_data(conditional_aligned_new_auto<T, Align>(other.size())), m_cols(other.m_cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = other.size())
+    smart_copy(other.m_data, other.m_data + other.size(), m_data);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index size, Index /*rows*/, Index cols)
+      : m_data(conditional_aligned_new_auto<T, Align>(size)), m_cols(cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(DenseStorage_impl&& other) noexcept
+      : m_data(other.m_data), m_cols(other.m_cols) {
+    other.m_data = nullptr;
+    other.m_cols = 0;
+  }
+  EIGEN_DEVICE_FUNC ~DenseStorage_impl() { conditional_aligned_delete_auto<T, Align>(m_data, size()); }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl& other) {
+    resize(other.size(), other.rows(), other.cols());
+    smart_copy(other.m_data, other.m_data + other.size(), m_data);
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(DenseStorage_impl&& other) noexcept {
+    this->swap(other);
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) noexcept {
+    numext::swap(m_data, other.m_data);
+    numext::swap(m_cols, other.m_cols);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index size, Index /*rows*/, Index cols) {
+    m_data = conditional_aligned_realloc_new_auto<T, Align>(m_data, size, this->size());
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index size, Index /*rows*/, Index cols) {
+    Index oldSize = this->size();
+    if (oldSize != size) {
+      conditional_aligned_delete_auto<T, Align>(m_data, oldSize);
+      m_data = conditional_aligned_new_auto<T, Align>(size);
+      EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+    }
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return Rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return Rows * m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data; }
+};
+template <typename T, int Options>
+class DenseStorage_impl<T, Dynamic, Dynamic, Dynamic, Options> {
+  static constexpr bool Align = (Options & DontAlign) == 0;
+  T* m_data = nullptr;
+  Index m_rows = 0;
+  Index m_cols = 0;
+
+ public:
+  static constexpr int Size = Dynamic;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(const DenseStorage_impl& other)
+      : m_data(conditional_aligned_new_auto<T, Align>(other.size())), m_rows(other.m_rows), m_cols(other.m_cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = other.size())
+    smart_copy(other.m_data, other.m_data + other.size(), m_data);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(Index size, Index rows, Index cols)
+      : m_data(conditional_aligned_new_auto<T, Align>(size)), m_rows(rows), m_cols(cols) {
+    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl(DenseStorage_impl&& other) noexcept
+      : m_data(other.m_data), m_rows(other.m_rows), m_cols(other.m_cols) {
+    other.m_data = nullptr;
+    other.m_rows = 0;
+    other.m_cols = 0;
+  }
+  EIGEN_DEVICE_FUNC ~DenseStorage_impl() { conditional_aligned_delete_auto<T, Align>(m_data, size()); }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(const DenseStorage_impl& other) {
+    resize(other.size(), other.rows(), other.cols());
+    smart_copy(other.m_data, other.m_data + other.size(), m_data);
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage_impl& operator=(DenseStorage_impl&& other) noexcept {
+    this->swap(other);
+    return *this;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage_impl& other) noexcept {
+    numext::swap(m_data, other.m_data);
+    numext::swap(m_rows, other.m_rows);
+    numext::swap(m_cols, other.m_cols);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index size, Index rows, Index cols) {
+    m_data = conditional_aligned_realloc_new_auto<T, Align>(m_data, size, this->size());
+    m_rows = rows;
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index size, Index rows, Index cols) {
+    Index oldSize = this->size();
+    if (oldSize != size) {
+      conditional_aligned_delete_auto<T, Align>(m_data, oldSize);
+      m_data = conditional_aligned_new_auto<T, Align>(size);
+      EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+    }
+    m_rows = rows;
+    m_cols = cols;
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index rows() const { return m_rows; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index cols() const { return m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr Index size() const { return m_rows * m_cols; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data; }
+};
+template <typename T, int Size, int Rows, int Cols>
+struct use_default_move {
+  static constexpr bool DynamicObject = Size == Dynamic;
+  static constexpr bool TrivialObject =
+      (!NumTraits<T>::RequireInitialization) && (Rows >= 0) && (Cols >= 0) && (Size == Rows * Cols);
+  static constexpr bool value = DynamicObject || TrivialObject;
+};
 }  // end namespace internal
 
 /** \internal
  *
- * \class DenseStorage
+ * \class DenseStorage_impl
  * \ingroup Core_Module
  *
  * \brief Stores the data of a matrix
@@ -174,201 +537,42 @@
  * \sa Matrix
  */
 template <typename T, int Size, int Rows, int Cols, int Options,
-          bool Trivial = internal::use_trivial_ctors<Size, Rows, Cols>::value>
-class DenseStorage;
-
-// fixed-size storage with fixed dimensions
-template <typename T, int Size, int Rows, int Cols, int Options>
-class DenseStorage<T, Size, Rows, Cols, Options, true> : internal::DenseStorageIndices<Rows, Cols> {
-  using Base = internal::DenseStorageIndices<Rows, Cols>;
-
-  internal::plain_array<T, Size, Options> m_data;
+          bool Trivial = internal::use_default_move<T, Size, Rows, Cols>::value>
+class DenseStorage : public internal::DenseStorage_impl<T, Size, Rows, Cols, Options> {
+  using Base = internal::DenseStorage_impl<T, Size, Rows, Cols, Options>;
 
  public:
-  using Base::cols;
-  using Base::rows;
-#ifndef EIGEN_DENSE_STORAGE_CTOR_PLUGIN
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE DenseStorage() = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(const DenseStorage&) = default;
-#else
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE DenseStorage() { EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = Size) }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(const DenseStorage& other)
-      : Base(other), m_data(other.m_data) {
-    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN(Index size = Size)
-  }
-#endif
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(DenseStorage&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(const DenseStorage&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(DenseStorage&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(Index size, Index rows, Index cols) : Base(rows, cols) {
-    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
-    EIGEN_UNUSED_VARIABLE(size);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage& other) {
-    numext::swap(m_data, other.m_data);
-    Base::swap(other);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index rows, Index cols) {
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index rows, Index cols) {
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data.array; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data.array; }
-};
-// fixed-size storage with dynamic dimensions
-template <typename T, int Size, int Rows, int Cols, int Options>
-class DenseStorage<T, Size, Rows, Cols, Options, false> : internal::DenseStorageIndices<Rows, Cols> {
-  using Base = internal::DenseStorageIndices<Rows, Cols>;
-
-  internal::plain_array<T, Size, Options> m_data;
-
- public:
-  using Base::cols;
-  using Base::rows;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE DenseStorage() = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(const DenseStorage& other) : Base(other), m_data() {
-    Index size = other.size();
-    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
-    internal::smart_copy(other.m_data.array, other.m_data.array + size, m_data.array);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(DenseStorage&& other) : Base(other), m_data() {
-    Index size = other.size();
-    internal::smart_move(other.m_data.array, other.m_data.array + size, m_data.array);
-    other.resize(Size, 0, 0);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(const DenseStorage& other) {
-    Base::set(other.rows(), other.cols());
-    Index size = other.size();
-    internal::smart_copy(other.m_data.array, other.m_data.array + size, m_data.array);
-    return *this;
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(DenseStorage&& other) {
-    Base::set(other.rows(), other.cols());
-    Index size = other.size();
-    internal::smart_move(other.m_data.array, other.m_data.array + size, m_data.array);
-    other.resize(Size, 0, 0);
-    return *this;
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(Index size, Index rows, Index cols) : Base(rows, cols) {
-    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
-    EIGEN_UNUSED_VARIABLE(size);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage& other) {
-    Index thisSize = this->size();
-    Index otherSize = other.size();
-    Index commonSize = numext::mini(thisSize, otherSize);
-    std::swap_ranges(m_data.array, m_data.array + commonSize, other.m_data.array);
-    if (thisSize > otherSize)
-      internal::smart_move(m_data.array + commonSize, m_data.array + thisSize, other.m_data.array + commonSize);
-    else if (otherSize > thisSize)
-      internal::smart_move(other.m_data.array + commonSize, other.m_data.array + otherSize, m_data.array + commonSize);
-    Base::swap(other);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index rows, Index cols) {
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index rows, Index cols) {
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data.array; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data.array; }
-};
-// null matrix specialization
-template <typename T, int Rows, int Cols, int Options>
-class DenseStorage<T, 0, Rows, Cols, Options, true> : internal::DenseStorageIndices<Rows, Cols> {
-  using Base = internal::DenseStorageIndices<Rows, Cols>;
-
- public:
-  using Base::cols;
-  using Base::rows;
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage() = default;
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(const DenseStorage&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(DenseStorage&&) = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(Index size, Index rows, Index cols)
+      : Base(size, rows, cols) {}
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(const DenseStorage&) = default;
+  // if DenseStorage meets the requirements of use_default_move, then use the move construction and move assignment
+  // operation defined in DenseStorage_impl, or the compiler-generated version if none is defined
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(DenseStorage&&) = default;
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(DenseStorage&&) = default;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(Index /*size*/, Index rows, Index cols)
-      : Base(rows, cols) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage& other) noexcept { Base::swap(other); }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index /*size*/, Index rows, Index cols) {
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index /*size*/, Index rows, Index cols) {
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return nullptr; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return nullptr; }
 };
-// dynamic matrix specialization
-template <typename T, int Rows, int Cols, int Options>
-class DenseStorage<T, Dynamic, Rows, Cols, Options, false> : internal::DenseStorageIndices<Rows, Cols> {
-  using Base = internal::DenseStorageIndices<Rows, Cols>;
-  static constexpr int Size = Dynamic;
-  static constexpr bool Align = (Options & DontAlign) == 0;
-
-  T* m_data;
+template <typename T, int Size, int Rows, int Cols, int Options>
+class DenseStorage<T, Size, Rows, Cols, Options, false>
+    : public internal::DenseStorage_impl<T, Size, Rows, Cols, Options> {
+  using Base = internal::DenseStorage_impl<T, Size, Rows, Cols, Options>;
 
  public:
-  using Base::cols;
-  using Base::rows;
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage() : m_data(nullptr) {}
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(const DenseStorage& other)
-      : Base(other), m_data(internal::conditional_aligned_new_auto<T, Align>(other.size())) {
-    Index size = other.size();
-    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
-    internal::smart_copy(other.m_data, other.m_data + size, m_data);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(DenseStorage&& other) noexcept
-      : Base(other), m_data(other.m_data) {
-    other.set(0, 0);
-    other.m_data = nullptr;
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(const DenseStorage& other) {
-    Base::set(other.rows(), other.cols());
-    Index size = other.size();
-    m_data = internal::conditional_aligned_new_auto<T, Align>(size);
-    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
-    internal::smart_copy(other.m_data, other.m_data + size, m_data);
-    return *this;
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(DenseStorage&& other) noexcept {
-    this->swap(other);
-    return *this;
-  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage() = default;
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(const DenseStorage&) = default;
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(Index size, Index rows, Index cols)
-      : Base(rows, cols), m_data(internal::conditional_aligned_new_auto<T, Align>(size)) {
-    EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
+      : Base(size, rows, cols) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(const DenseStorage&) = default;
+  // if DenseStorage does not meet the requirements of use_default_move, then defer to the copy construction and copy
+  // assignment behavior
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage(DenseStorage&& other)
+      : DenseStorage(static_cast<const DenseStorage&>(other)) {}
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr DenseStorage& operator=(DenseStorage&& other) {
+    *this = other;
+    return *this;
   }
-  EIGEN_DEVICE_FUNC ~DenseStorage() {
-    Index size = this->size();
-    internal::conditional_aligned_delete_auto<T, Align>(m_data, size);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void swap(DenseStorage& other) noexcept {
-    numext::swap(m_data, other.m_data);
-    Base::swap(other);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void conservativeResize(Index size, Index rows, Index cols) {
-    Index oldSize = this->size();
-    m_data = internal::conditional_aligned_realloc_new_auto<T, Align>(m_data, size, oldSize);
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void resize(Index size, Index rows, Index cols) {
-    Index oldSize = this->size();
-    if (size != oldSize) {
-      internal::conditional_aligned_delete_auto<T, Align>(m_data, oldSize);
-      if (size > 0)  // >0 and not simply !=0 to let the compiler knows that size cannot be negative
-      {
-        m_data = internal::conditional_aligned_new_auto<T, Align>(size);
-        EIGEN_INTERNAL_DENSE_STORAGE_CTOR_PLUGIN({})
-      } else
-        m_data = nullptr;
-    }
-    Base::set(rows, cols);
-  }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr T* data() { return m_data; }
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr const T* data() const { return m_data; }
 };
+
 }  // end namespace Eigen
 
 #endif  // EIGEN_MATRIX_H
diff --git a/Eigen/src/Core/util/Memory.h b/Eigen/src/Core/util/Memory.h
index d59071f..2acdd9d 100644
--- a/Eigen/src/Core/util/Memory.h
+++ b/Eigen/src/Core/util/Memory.h
@@ -147,7 +147,7 @@
   check_that_malloc_is_allowed();
   EIGEN_USING_STD(malloc)
   void* original = malloc(size + alignment);
-  if (original == 0) return 0;
+  if (original == nullptr) return nullptr;
   uint8_t offset = static_cast<uint8_t>(alignment - (reinterpret_cast<std::size_t>(original) & (alignment - 1)));
   void* aligned = static_cast<void*>(static_cast<uint8_t*>(original) + offset);
   *(static_cast<uint8_t*>(aligned) - 1) = offset;
@@ -391,7 +391,8 @@
 
 template <typename T>
 EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE void check_size_for_overflow(std::size_t size) {
-  if (size > std::size_t(-1) / sizeof(T)) throw_std_bad_alloc();
+  constexpr std::size_t max_elements = PTRDIFF_MAX / sizeof(T);
+  if (size > max_elements) throw_std_bad_alloc();
 }
 
 /** \internal Allocates \a size objects of type T. The returned pointer is guaranteed to have 16 bytes alignment.
@@ -473,7 +474,7 @@
 
 template <typename T, bool Align>
 EIGEN_DEVICE_FUNC inline T* conditional_aligned_new_auto(std::size_t size) {
-  if (size == 0) return 0;  // short-cut. Also fixes Bug 884
+  if (size == 0) return nullptr;  // short-cut. Also fixes Bug 884
   check_size_for_overflow<T>(size);
   T* result = static_cast<T*>(conditional_aligned_malloc<Align>(sizeof(T) * size));
   if (NumTraits<T>::RequireInitialization) {
diff --git a/test/MovableScalar.h b/test/MovableScalar.h
index c8bf546..6a046de 100644
--- a/test/MovableScalar.h
+++ b/test/MovableScalar.h
@@ -10,24 +10,42 @@
 #ifndef EIGEN_MISC_MOVABLE_SCALAR_H
 #define EIGEN_MISC_MOVABLE_SCALAR_H
 
-#include <vector>
-
 namespace Eigen {
-template <typename Scalar, typename Base = std::vector<Scalar>>
-struct MovableScalar : public Base {
-  MovableScalar() = default;
-  ~MovableScalar() = default;
-  MovableScalar(const MovableScalar&) = default;
-  MovableScalar(MovableScalar&& other) = default;
-  MovableScalar& operator=(const MovableScalar&) = default;
-  MovableScalar& operator=(MovableScalar&& other) = default;
-  MovableScalar(Scalar scalar) : Base(100, scalar) {}
+template <typename Scalar>
+struct MovableScalar {
+  MovableScalar() : m_data(new Scalar) {}
+  ~MovableScalar() { delete m_data; }
+  MovableScalar(const MovableScalar& other) : m_data(new Scalar) { set(other.get()); }
+  MovableScalar(MovableScalar&& other) noexcept : m_data(other.m_data) { other.m_data = nullptr; }
+  MovableScalar& operator=(const MovableScalar& other) {
+    set(other.get());
+    return *this;
+  }
+  MovableScalar& operator=(MovableScalar&& other) noexcept {
+    m_data = other.m_data;
+    other.m_data = nullptr;
+    return *this;
+  }
+  MovableScalar(const Scalar& scalar) : m_data(new Scalar) { set(scalar); }
 
-  operator Scalar() const { return this->size() > 0 ? this->back() : Scalar(); }
+  operator Scalar() const { return get(); }
+
+ private:
+  void set(const Scalar& value) {
+    eigen_assert(m_data != nullptr);
+    // suppress compiler warnings
+    if (m_data != nullptr) *m_data = value;
+  }
+  Scalar get() const {
+    eigen_assert(m_data != nullptr);
+    // suppress compiler warnings
+    return m_data == nullptr ? Scalar() : *m_data;
+  }
+  Scalar* m_data = nullptr;
 };
 
 template <typename Scalar>
-struct NumTraits<MovableScalar<Scalar>> : GenericNumTraits<Scalar> {
+struct NumTraits<MovableScalar<Scalar>> : NumTraits<Scalar> {
   enum { RequireInitialization = 1 };
 };
 
diff --git a/test/dense_storage.cpp b/test/dense_storage.cpp
index 5d0083f..0f6ab64 100644
--- a/test/dense_storage.cpp
+++ b/test/dense_storage.cpp
@@ -11,29 +11,38 @@
 
 #include "main.h"
 #include "AnnoyingScalar.h"
+#include "MovableScalar.h"
 #include "SafeScalar.h"
 
 #include <Eigen/Core>
 
 using DenseStorageD3x3 = Eigen::DenseStorage<double, 9, 3, 3, 0>;
-static_assert(std::is_trivially_move_constructible<DenseStorageD3x3>::value,
-              "DenseStorage not trivially_move_constructible");
-static_assert(std::is_trivially_move_assignable<DenseStorageD3x3>::value, "DenseStorage not trivially_move_assignable");
 #if !defined(EIGEN_DENSE_STORAGE_CTOR_PLUGIN)
 static_assert(std::is_trivially_copy_constructible<DenseStorageD3x3>::value,
               "DenseStorage not trivially_copy_constructible");
+static_assert(std::is_trivially_move_constructible<DenseStorageD3x3>::value,
+              "DenseStorage not trivially_move_constructible");
 static_assert(std::is_trivially_copy_assignable<DenseStorageD3x3>::value, "DenseStorage not trivially_copy_assignable");
-static_assert(std::is_trivially_copyable<DenseStorageD3x3>::value, "DenseStorage not trivially_copyable");
+static_assert(std::is_trivially_move_assignable<DenseStorageD3x3>::value, "DenseStorage not trivially_move_assignable");
 #endif
-
+// all plain object types conform to standard layout
+static_assert(std::is_standard_layout<Matrix4f>::value, "Matrix4f not standard_layout");
+static_assert(std::is_standard_layout<Array4f>::value, "Array4f not standard_layout");
+static_assert(std::is_standard_layout<VectorXf>::value, "VectorXf not standard_layout");
+static_assert(std::is_standard_layout<ArrayXf>::value, "ArrayXf not standard_layout");
+static_assert(std::is_standard_layout<MatrixXf>::value, "MatrixXf not standard_layout");
+static_assert(std::is_standard_layout<ArrayXXf>::value, "ArrayXXf not standard_layout");
+// all fixed-size, fixed-dimension plain object types are trivially default constructible
+static_assert(std::is_trivially_default_constructible<Matrix4f>::value, "Matrix4f not trivially_default_constructible");
+static_assert(std::is_trivially_default_constructible<Array4f>::value, "Array4f not trivially_default_constructible");
+// all fixed-size, fixed-dimension plain object types are trivially move constructible
 static_assert(std::is_trivially_move_constructible<Matrix4f>::value, "Matrix4f not trivially_move_constructible");
 static_assert(std::is_trivially_move_constructible<Array4f>::value, "Array4f not trivially_move_constructible");
 #if !defined(EIGEN_DENSE_STORAGE_CTOR_PLUGIN)
+// all fixed-size, fixed-dimension plain object types are trivially copy constructible
 static_assert(std::is_trivially_copy_constructible<Matrix4f>::value, "Matrix4f not trivially_copy_constructible");
 static_assert(std::is_trivially_copy_constructible<Array4f>::value, "Array4f not trivially_copy_constructible");
 #endif
-static_assert(std::is_trivially_default_constructible<Matrix4f>::value, "Matrix4f not trivially_default_constructible");
-static_assert(std::is_trivially_default_constructible<Array4f>::value, "Array4f not trivially_default_constructible");
 
 template <typename T, int Size, int Rows, int Cols>
 void dense_storage_copy(int rows, int cols) {
@@ -42,7 +51,7 @@
   const int size = rows * cols;
   DenseStorageType reference(size, rows, cols);
   T* raw_reference = reference.data();
-  for (int i = 0; i < size; ++i) raw_reference[i] = static_cast<T>(i);
+  for (int i = 0; i < size; ++i) raw_reference[i] = internal::random<T>();
 
   DenseStorageType copied_reference(reference);
   const T* raw_copied_reference = copied_reference.data();
@@ -56,7 +65,7 @@
   const int size = rows * cols;
   DenseStorageType reference(size, rows, cols);
   T* raw_reference = reference.data();
-  for (int i = 0; i < size; ++i) raw_reference[i] = static_cast<T>(i);
+  for (int i = 0; i < size; ++i) raw_reference[i] = internal::random<T>();
 
   DenseStorageType copied_reference;
   copied_reference = reference;
@@ -65,30 +74,25 @@
 }
 
 template <typename T, int Size, int Rows, int Cols>
-void dense_storage_swap(int rows0, int cols0, int rows1, int cols1) {
+void dense_storage_swap(int rowsa, int colsa, int rowsb, int colsb) {
   typedef DenseStorage<T, Size, Rows, Cols, 0> DenseStorageType;
 
-  const int size0 = rows0 * cols0;
-  DenseStorageType a(size0, rows0, cols0);
-  for (int i = 0; i < size0; ++i) {
-    a.data()[i] = static_cast<T>(i);
-  }
+  const int sizea = rowsa * colsa;
+  ArrayX<T> referencea(sizea);
+  referencea.setRandom();
+  DenseStorageType a(sizea, rowsa, colsa);
+  for (int i = 0; i < sizea; ++i) a.data()[i] = referencea(i);
 
-  const int size1 = rows1 * cols1;
-  DenseStorageType b(size1, rows1, cols1);
-  for (int i = 0; i < size1; ++i) {
-    b.data()[i] = static_cast<T>(-i);
-  }
+  const int sizeb = rowsb * colsb;
+  ArrayX<T> referenceb(sizeb);
+  referenceb.setRandom();
+  DenseStorageType b(sizeb, rowsb, colsb);
+  for (int i = 0; i < sizeb; ++i) b.data()[i] = referenceb(i);
 
   a.swap(b);
 
-  for (int i = 0; i < size0; ++i) {
-    VERIFY_IS_EQUAL(b.data()[i], static_cast<T>(i));
-  }
-
-  for (int i = 0; i < size1; ++i) {
-    VERIFY_IS_EQUAL(a.data()[i], static_cast<T>(-i));
-  }
+  for (int i = 0; i < sizea; i++) VERIFY_IS_EQUAL(b.data()[i], referencea(i));
+  for (int i = 0; i < sizeb; i++) VERIFY_IS_EQUAL(a.data()[i], referenceb(i));
 }
 
 template <typename T, int Size, std::size_t Alignment>
@@ -104,12 +108,12 @@
   };
   VERIFY_IS_EQUAL(std::alignment_of<Nested1>::value, Alignment);
 
-  VERIFY_IS_EQUAL((std::alignment_of<internal::plain_array<T, Size, AutoAlign, Alignment> >::value), Alignment);
+  VERIFY_IS_EQUAL((std::alignment_of<internal::plain_array<T, Size, AutoAlign, Alignment>>::value), Alignment);
 
   const std::size_t default_alignment = internal::compute_default_alignment<T, Size>::value;
   if (default_alignment > 0) {
-    VERIFY_IS_EQUAL((std::alignment_of<DenseStorage<T, Size, 1, 1, AutoAlign> >::value), default_alignment);
-    VERIFY_IS_EQUAL((std::alignment_of<Matrix<T, Size, 1, AutoAlign> >::value), default_alignment);
+    VERIFY_IS_EQUAL((std::alignment_of<DenseStorage<T, Size, 1, 1, AutoAlign>>::value), default_alignment);
+    VERIFY_IS_EQUAL((std::alignment_of<Matrix<T, Size, 1, AutoAlign>>::value), default_alignment);
     struct Nested2 {
       Matrix<T, Size, 1, AutoAlign> mat;
     };
@@ -185,11 +189,90 @@
   dense_storage_alignment<T, 16, 64>();
 }
 
+template <typename PlainType>
+void plaintype_tests() {
+  constexpr int RowsAtCompileTime = PlainType::RowsAtCompileTime;
+  constexpr int ColsAtCompileTime = PlainType::ColsAtCompileTime;
+  constexpr int MaxRowsAtCompileTime = PlainType::MaxRowsAtCompileTime;
+  constexpr int MaxColsAtCompileTime = PlainType::MaxColsAtCompileTime;
+  const Index expectedDefaultRows = RowsAtCompileTime == Dynamic ? 0 : RowsAtCompileTime;
+  const Index expectedDefaultCols = ColsAtCompileTime == Dynamic ? 0 : ColsAtCompileTime;
+  const Index minRows = RowsAtCompileTime == Dynamic ? 0 : RowsAtCompileTime;
+  const Index minCols = ColsAtCompileTime == Dynamic ? 0 : ColsAtCompileTime;
+  const Index maxRows = MaxRowsAtCompileTime == Dynamic ? 100 : MaxRowsAtCompileTime;
+  const Index maxCols = MaxColsAtCompileTime == Dynamic ? 100 : MaxColsAtCompileTime;
+  const Index rows = internal::random<Index>(minRows, maxRows);
+  const Index cols = internal::random<Index>(minCols, maxCols);
+  // default construction
+  PlainType m0;
+  VERIFY_IS_EQUAL(m0.rows(), expectedDefaultRows);
+  VERIFY_IS_EQUAL(m0.cols(), expectedDefaultCols);
+  m0.resize(rows, cols);
+  m0.setRandom();
+  // copy construction
+  PlainType m1(m0);
+  VERIFY_IS_EQUAL(m1.rows(), m0.rows());
+  VERIFY_IS_EQUAL(m1.cols(), m0.cols());
+  VERIFY_IS_CWISE_EQUAL(m1, m0);
+  // move construction
+  PlainType m2(std::move(m1));
+  VERIFY_IS_EQUAL(m2.rows(), m0.rows());
+  VERIFY_IS_EQUAL(m2.cols(), m0.cols());
+  VERIFY_IS_CWISE_EQUAL(m2, m0);
+  // check that object is usable after move construction
+  m1.resize(minRows, minCols);
+  m1.setRandom();
+  // copy assignment
+  m1 = m0;
+  VERIFY_IS_EQUAL(m1.rows(), m0.rows());
+  VERIFY_IS_EQUAL(m1.cols(), m0.cols());
+  VERIFY_IS_CWISE_EQUAL(m1, m0);
+  // move assignment
+  m2.resize(minRows, minCols);
+  m2.setRandom();
+  m2 = std::move(m1);
+  VERIFY_IS_EQUAL(m2.rows(), m0.rows());
+  VERIFY_IS_EQUAL(m2.cols(), m0.cols());
+  VERIFY_IS_CWISE_EQUAL(m2, m0);
+  // check that object is usable after move assignment
+  m1.resize(minRows, minCols);
+  m1.setRandom();
+  m1 = m2;
+  VERIFY_IS_EQUAL(m1.rows(), m0.rows());
+  VERIFY_IS_EQUAL(m1.cols(), m0.cols());
+  VERIFY_IS_CWISE_EQUAL(m1, m0);
+}
+
 EIGEN_DECLARE_TEST(dense_storage) {
   dense_storage_tests<int>();
   dense_storage_tests<float>();
-  dense_storage_tests<SafeScalar<float> >();
+  dense_storage_tests<SafeScalar<float>>();
+  dense_storage_tests<MovableScalar<float>>();
   dense_storage_tests<AnnoyingScalar>();
+  for (int i = 0; i < g_repeat; i++) {
+    plaintype_tests<Matrix<float, 0, 0, ColMajor>>();
+    plaintype_tests<Matrix<float, Dynamic, Dynamic, ColMajor, 0, 0>>();
+
+    plaintype_tests<Matrix<float, 16, 16, ColMajor>>();
+    plaintype_tests<Matrix<float, 16, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<float, Dynamic, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<float, Dynamic, Dynamic, ColMajor, 16, 16>>();
+
+    plaintype_tests<Matrix<SafeScalar<float>, 16, 16, ColMajor>>();
+    plaintype_tests<Matrix<SafeScalar<float>, 16, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<SafeScalar<float>, Dynamic, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<SafeScalar<float>, Dynamic, Dynamic, ColMajor, 16, 16>>();
+
+    plaintype_tests<Matrix<MovableScalar<float>, 16, 16, ColMajor>>();
+    plaintype_tests<Matrix<MovableScalar<float>, 16, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<MovableScalar<float>, Dynamic, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<MovableScalar<float>, Dynamic, Dynamic, ColMajor, 16, 16>>();
+
+    plaintype_tests<Matrix<AnnoyingScalar, 16, 16, ColMajor>>();
+    plaintype_tests<Matrix<AnnoyingScalar, 16, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<AnnoyingScalar, Dynamic, Dynamic, ColMajor>>();
+    plaintype_tests<Matrix<AnnoyingScalar, Dynamic, Dynamic, ColMajor, 16, 16>>();
+  }
 }
 
 #undef EIGEN_TESTING_PLAINOBJECT_CTOR
\ No newline at end of file