WIP: make Infallible an alias for !

Author: nikomatsakis

library/core/src/convert/mod.rs

@@ -34,9 +34,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use crate::fmt;
-use crate::hash::{Hash, Hasher};
-
 mod num;
 
 #[unstable(feature = "convert_float_to_int", issue = "67057")]
@@ -675,64 +672,4 @@ impl AsRef<str> for str {
 ///
 /// [never]: ../../std/primitive.never.html
 #[stable(feature = "convert_infallible", since = "1.34.0")]
-#[derive(Copy)]
-pub enum Infallible {}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl Clone for Infallible {
-    fn clone(&self) -> Infallible {
-        match *self {}
-    }
-}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl fmt::Debug for Infallible {
-    fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match *self {}
-    }
-}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl fmt::Display for Infallible {
-    fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match *self {}
-    }
-}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl PartialEq for Infallible {
-    fn eq(&self, _: &Infallible) -> bool {
-        match *self {}
-    }
-}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl Eq for Infallible {}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl PartialOrd for Infallible {
-    fn partial_cmp(&self, _other: &Self) -> Option<crate::cmp::Ordering> {
-        match *self {}
-    }
-}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl Ord for Infallible {
-    fn cmp(&self, _other: &Self) -> crate::cmp::Ordering {
-        match *self {}
-    }
-}
-
-#[stable(feature = "convert_infallible", since = "1.34.0")]
-impl From<!> for Infallible {
-    fn from(x: !) -> Self {
-        x
-    }
-}
-
-#[stable(feature = "convert_infallible_hash", since = "1.44.0")]
-impl Hash for Infallible {
-    fn hash<H: Hasher>(&self, _: &mut H) {
-        match *self {}
-    }
-}
+pub type Infallible = !;

library/core/src/num/error.rs

@@ -1,6 +1,5 @@
 //! Error types for conversion to integral types.
 
-use crate::convert::Infallible;
 use crate::fmt;
 
 /// The error type returned when a checked integral type conversion fails.
@@ -28,13 +27,6 @@ impl fmt::Display for TryFromIntError {
     }
 }
 
-#[stable(feature = "try_from", since = "1.34.0")]
-impl From<Infallible> for TryFromIntError {
-    fn from(x: Infallible) -> TryFromIntError {
-        match x {}
-    }
-}
-
 #[stable(feature = "never_type", since = "1.49.0")]
 impl From<!> for TryFromIntError {
     fn from(never: !) -> TryFromIntError {

library/std/src/error.rs

@@ -17,7 +17,6 @@
 mod tests;
 
 use core::array;
-use core::convert::Infallible;
 
 use crate::alloc::{AllocError, LayoutError};
 use crate::any::TypeId;
@@ -456,13 +455,6 @@ impl Error for string::FromUtf16Error {
     }
 }
 
-#[stable(feature = "str_parse_error2", since = "1.8.0")]
-impl Error for Infallible {
-    fn description(&self) -> &str {
-        match *self {}
-    }
-}
-
 #[stable(feature = "decode_utf16", since = "1.9.0")]
 impl Error for char::DecodeUtf16Error {
     #[allow(deprecated)]