🐛 Fix sized issue with indivisible sizes

Problem:
- `sized` does not work correctly when the sizes of `T` and `U` are not
  multiples, for example when computing the number of 4-byte values required to
  hold N 3-byte values.

Solution:
- Fix it.

Author: elbeno

include/stdx/utility.hpp

@@ -116,7 +116,7 @@ template <typename T, typename U>
     if constexpr (sizeof(T) == sizeof(U)) {
         return sz;
     } else if constexpr (sizeof(T) > sizeof(U)) {
-        return sz * (sizeof(T) / sizeof(U));
+        return (sz * sizeof(T) / sizeof(U)) + (sizeof(T) % sizeof(U) & 1u);
     } else {
         return (sz * sizeof(T) + sizeof(U) - 1) / sizeof(U);
     }

test/utility.cpp

@@ -130,6 +130,18 @@ TEST_CASE("sized<T> aliases", "[utility]") {
     static_assert(stdx::sized64{1}.in<std::uint64_t>() == 1);
 }
 
+TEST_CASE("sized<T> in (downsize not divisible)", "[utility]") {
+    using T = std::array<char, 3>;
+    static_assert(sizeof(T) == 3);
+    static_assert(stdx::sized<std::uint32_t>{2}.in<T>() == 3);
+}
+
+TEST_CASE("sized<T> in (upsize not divisible)", "[utility]") {
+    using T = std::array<char, 3>;
+    static_assert(sizeof(T) == 3);
+    static_assert(stdx::sized<T>{3}.in<std::uint32_t>() == 3);
+}
+
 TEST_CASE("CX_VALUE structural value", "[utility]") {
     auto x = CX_VALUE(42);
     static_assert(x() == 42);