+#[stable(feature = "str_parse_error2", since = "1.8.0")]
+impl Error for string::ParseError {
+ fn description(&self) -> &str {
+ match *self {}
+ }
+}
+
+#[stable(feature = "box_error", since = "1.7.0")]
+impl<T: Error> Error for Box<T> {
+ fn description(&self) -> &str {
+ Error::description(&**self)
+ }
+
+ fn cause(&self) -> Option<&Error> {
+ Error::cause(&**self)
+ }
+}
+