Move error trait into core

library/core/src/num/error.rs

@@ -1,6 +1,8 @@
 //! Error types for conversion to integral types.
 
 use crate::convert::Infallible;
+#[cfg(not(bootstrap))]
+use crate::error::Error;
 use crate::fmt;
 
 /// The error type returned when a checked integral type conversion fails.
@@ -144,3 +146,21 @@ impl fmt::Display for ParseIntError {
         self.__description().fmt(f)
     }
 }
+
+#[cfg(not(bootstrap))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Error for ParseIntError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        self.__description()
+    }
+}
+
+#[cfg(not(bootstrap))]
+#[stable(feature = "try_from", since = "1.34.0")]
+impl Error for TryFromIntError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        self.__description()
+    }
+}