interim checkin of the rebased code

src/lmdb/key_stream.h

@@ -133,6 +133,7 @@ namespace lmdb
         //! \pre `!is_end()` \return Current key
         K get_key() const noexcept
         {
+            static_assert(std::is_trivially_copyable<K>(), "key is not memcpy safe");
             assert(!is_end());
             K out;
             std::memcpy(std::addressof(out), key.data(), sizeof(out));

src/lmdb/table.h

@@ -55,7 +55,7 @@ namespace lmdb
         static expect<F> get_value(MDB_val value) noexcept
         {
             static_assert(std::is_same<U, V>(), "bad MONERO_FIELD?");
-            static_assert(std::is_pod<F>(), "F must be POD");
+            static_assert(std::is_trivially_copyable<F>(), "F must be memcpy safe");
             static_assert(sizeof(F) + offset <= sizeof(U), "bad field type and/or offset");
 
             if (value.mv_size != sizeof(U))

src/lmdb/util.h

@@ -111,6 +111,7 @@ namespace lmdb
     template<typename T, std::size_t offset = 0>
     inline int less(MDB_val const* left, MDB_val const* right) noexcept
     {
+        static_assert(std::is_trivially_copyable<T>(), "memcpy will not work");
         if (!left || !right || left->mv_size < sizeof(T) + offset || right->mv_size < sizeof(T) + offset)
         {
             assert("invalid use of custom comparison" == 0);
@@ -127,7 +128,7 @@ namespace lmdb
     /*!
         A LMDB comparison function that uses `std::memcmp`.
 
-        \toaram T is `!epee::has_padding`
+        \toaram T has standard layout and an alignment of 1
         \tparam offset to `T` within the value.
 
         \return The result of `std::memcmp` over the value.
@@ -135,7 +136,7 @@ namespace lmdb
     template<typename T, std::size_t offset = 0>
     inline int compare(MDB_val const* left, MDB_val const* right) noexcept
     {
-        static_assert(!epee::has_padding<T>(), "memcmp will not work");
+        static_assert(std::is_standard_layout<T>() && alignof(T) == 1, "memcmp will not work");
         if (!left || !right || left->mv_size < sizeof(T) + offset || right->mv_size < sizeof(T) + offset)
         {
             assert("invalid use of custom comparison" == 0);

src/lmdb/value_stream.h

@@ -162,8 +162,8 @@ namespace lmdb
         G get_value() const noexcept
         {
             static_assert(std::is_same<U, T>(), "bad MONERO_FIELD usage?");
-            static_assert(std::is_pod<U>(), "value type must be pod");
-            static_assert(std::is_pod<G>(), "field type must be pod");
+            static_assert(std::is_trivially_copyable<U>(), "value type must be memcpy safe");
+            static_assert(std::is_trivially_copyable<G>(), "field type must be memcpy safe");
             static_assert(sizeof(G) + uoffset <= sizeof(U), "bad field and/or offset");
             assert(sizeof(G) + uoffset <= values.size());
             assert(!is_end());