add Error trait for some struct

src/iface/route.rs

@@ -12,6 +12,15 @@ use crate::wire::{Ipv6Address, Ipv6Cidr};
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct RouteTableFull;
 
+impl core::fmt::Display for RouteTableFull {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "Route table full")
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for RouteTableFull {}
+
 /// A prefix of addresses that should be routed via a router
 #[derive(Debug, Clone, Copy)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]

src/socket/udp.rs

@@ -23,6 +23,18 @@ pub enum BindError {
     Unaddressable,
 }
 
+impl core::fmt::Display for BindError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            BindError::InvalidState => write!(f, "invalid state"),
+            BindError::Unaddressable => write!(f, "unaddressable"),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for BindError {}
+
 /// Error returned by [`Socket::send`]
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -31,6 +43,18 @@ pub enum SendError {
     BufferFull,
 }
 
+impl core::fmt::Display for SendError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            SendError::Unaddressable => write!(f, "unaddressable"),
+            SendError::BufferFull => write!(f, "buffer full"),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for SendError {}
+
 /// Error returned by [`Socket::recv`]
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -38,6 +62,17 @@ pub enum RecvError {
     Exhausted,
 }
 
+impl core::fmt::Display for RecvError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            RecvError::Exhausted => write!(f, "exhausted"),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for RecvError {}
+
 /// A User Datagram Protocol socket.
 ///
 /// A UDP socket is bound to a specific endpoint, and owns transmit and receive