Add MaxEncodedLen to implement_fixed! (#10768)

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

substrate/primitives/arithmetic/src/fixed_point.rs

@@ -369,6 +369,7 @@ macro_rules! implement_fixed {
 			Default,
 			Copy,
 			Clone,
+			codec::MaxEncodedLen,
 			PartialEq,
 			Eq,
 			PartialOrd,
@@ -667,6 +668,15 @@ macro_rules! implement_fixed {
 				assert!($name::DIV > 0);
 			}
 
+			#[test]
+			fn has_max_encoded_len() {
+				struct AsMaxEncodedLen<T: codec::MaxEncodedLen> {
+					_data: T,
+				}
+
+				let _ = AsMaxEncodedLen { _data: $name::min_value() };
+			}
+
 			#[test]
 			fn from_i129_works() {
 				let a = I129 { value: 1, negative: true };