Properly initialize math::interval<util::fixed_point>

libs/math/include/psemek/math/interval.hpp

@@ -9,36 +9,68 @@
 namespace psemek::math
 {
 
+	namespace detail
+	{
+
+		template <typename T>
+		concept has_min = requires ()
+		{
+			{ T::min() } -> std::same_as<T>;
+		};
+
+		template <typename T>
+		concept has_max = requires ()
+		{
+			{ T::max() } -> std::same_as<T>;
+		};
+
+	}
+
 	// Can be specialized in client code
 	template <typename T>
 	struct limits
 	{
 		static constexpr T min()
 		{
-			if constexpr (std::is_floating_point_v<T>)
+			if constexpr (detail::has_min<T>)
+			{
+				return T::min();
+			}
+			else if constexpr (std::is_floating_point_v<T>)
 			{
 				return -std::numeric_limits<T>::infinity();
 			}
-			else
+			else if constexpr (std::is_integral_v<T>)
 			{
 				return std::numeric_limits<T>::min();
 			}
+			else
+			{
+				static_assert("unknown type");
+			}
 		}
 
 		static constexpr T max()
 		{
-			if constexpr (std::is_floating_point_v<T>)
+			if constexpr (detail::has_max<T>)
+			{
+				return T::max();
+			}
+			else if constexpr (std::is_floating_point_v<T>)
 			{
 				return std::numeric_limits<T>::infinity();
 			}
-			else
+			else if constexpr (std::is_integral_v<T>)
 			{
 				return std::numeric_limits<T>::max();
 			}
+			else
+			{
+				static_assert("unknown type");
+			}
 		}
 	};
 
-
 	template <typename T>
 	struct interval_iterator
 	{