feat: constructors of cartesian_vector refactored

src/core/include/mp-units/cartesian_vector.h

@@ -53,26 +53,30 @@ public:
   T _coordinates_[3];
   using value_type = T;
 
-  cartesian_vector() = default;
   cartesian_vector(const cartesian_vector&) = default;
   cartesian_vector(cartesian_vector&&) = default;
   cartesian_vector& operator=(const cartesian_vector&) = default;
   cartesian_vector& operator=(cartesian_vector&&) = default;
 
-  template<std::convertible_to<T> Arg1, std::convertible_to<T>... Args>
-  constexpr cartesian_vector(Arg1&& arg1, Args&&... args) :
-      _coordinates_(std::forward<Arg1>(arg1), std::forward<Args>(args)...)
+  template<typename... Args>
+    requires(... && std::constructible_from<T, Args>)
+  constexpr explicit(!(... && std::convertible_to<Args, T>)) cartesian_vector(Args&&... args) :
+      _coordinates_{static_cast<T>(std::forward<Args>(args))...}
   {
   }
 
-  template<std::convertible_to<T> U>
-  constexpr cartesian_vector(const cartesian_vector<U>& other) : _coordinates_{other[0], other[1], other[2]}
+  template<typename U>
+    requires std::constructible_from<T, U>
+  constexpr explicit(!std::convertible_to<U, T>) cartesian_vector(const cartesian_vector<U>& other) :
+      _coordinates_{static_cast<T>(other[0]), static_cast<T>(other[1]), static_cast<T>(other[2])}
   {
   }
 
-  template<std::convertible_to<T> U>
-  constexpr cartesian_vector(cartesian_vector<U>&& other) :
-      _coordinates_{std::move(other[0]), std::move(other[1]), std::move(other[2])}
+  template<typename U>
+    requires std::constructible_from<T, U>
+  constexpr explicit(!std::convertible_to<U, T>) cartesian_vector(cartesian_vector<U>&& other) :
+      _coordinates_{static_cast<T>(std::move(other[0])), static_cast<T>(std::move(other[1])),
+                    static_cast<T>(std::move(other[2]))}
   {
   }