Auto merge of #138340 - oli-obk:one-size-fits-all, r=<try>

Remove some unsized tuple impls now that we don't support unsizing tuples anymore

Since #137728 there is no sound way to create unsized tuples anymore. While we can't remove them from the language due to people using `PhantomData<(T, U)>` where `U: ?Sized` (they'd have to use `(PhantomData<T>, PhantomData<U>)` now), we can remove the impls from libcore I believe.

r? ghost

library/core/src/fmt/mod.rs

@@ -2851,7 +2851,7 @@ macro_rules! tuple {
         maybe_tuple_doc! {
             $($name)+ @
             #[stable(feature = "rust1", since = "1.0.0")]
-            impl<$($name:Debug),+> Debug for ($($name,)+) where last_type!($($name,)+): ?Sized {
+            impl<$($name:Debug),+> Debug for ($($name,)+) {
                 #[allow(non_snake_case, unused_assignments)]
                 fn fmt(&self, f: &mut Formatter<'_>) -> Result {
                     let mut builder = f.debug_tuple("");
@@ -2882,11 +2882,6 @@ macro_rules! maybe_tuple_doc {
     };
 }
 
-macro_rules! last_type {
-    ($a:ident,) => { $a };
-    ($a:ident, $($rest_a:ident,)+) => { last_type!($($rest_a,)+) };
-}
-
 tuple! { E, D, C, B, A, Z, Y, X, W, V, U, T, }
 
 #[stable(feature = "rust1", since = "1.0.0")]

library/core/src/hash/mod.rs

@@ -886,7 +886,7 @@ mod impls {
             maybe_tuple_doc! {
                 $($name)+ @
                 #[stable(feature = "rust1", since = "1.0.0")]
-                impl<$($name: Hash),+> Hash for ($($name,)+) where last_type!($($name,)+): ?Sized {
+                impl<$($name: Hash),+> Hash for ($($name,)+) {
                     #[allow(non_snake_case)]
                     #[inline]
                     fn hash<S: Hasher>(&self, state: &mut S) {
@@ -912,11 +912,6 @@ mod impls {
         };
     }
 
-    macro_rules! last_type {
-        ($a:ident,) => { $a };
-        ($a:ident, $($rest_a:ident,)+) => { last_type!($($rest_a,)+) };
-    }
-
     impl_hash_tuple! {}
     impl_hash_tuple! { T }
     impl_hash_tuple! { T B }

library/core/src/ops/range.rs

@@ -1211,7 +1211,7 @@ pub enum OneSidedRangeBound {
 /// Types that implement `OneSidedRange<T>` must return `Bound::Unbounded`
 /// from one of `RangeBounds::start_bound` or `RangeBounds::end_bound`.
 #[unstable(feature = "one_sided_range", issue = "69780")]
-pub trait OneSidedRange<T: ?Sized>: RangeBounds<T> {
+pub trait OneSidedRange<T>: RangeBounds<T> {
     /// An internal-only helper function for `split_off` and
     /// `split_off_mut` that returns the bound of the one-sided range.
     fn bound(self) -> (OneSidedRangeBound, T);

library/core/src/tuple.rs

@@ -22,10 +22,7 @@ macro_rules! tuple_impls {
         maybe_tuple_doc! {
             $($T)+ @
             #[stable(feature = "rust1", since = "1.0.0")]
-            impl<$($T: PartialEq),+> PartialEq for ($($T,)+)
-            where
-                last_type!($($T,)+): ?Sized
-            {
+            impl<$($T: PartialEq),+> PartialEq for ($($T,)+) {
                 #[inline]
                 fn eq(&self, other: &($($T,)+)) -> bool {
                     $( ${ignore($T)} self.${index()} == other.${index()} )&&+
@@ -41,8 +38,6 @@ macro_rules! tuple_impls {
             $($T)+ @
             #[stable(feature = "rust1", since = "1.0.0")]
             impl<$($T: Eq),+> Eq for ($($T,)+)
-            where
-                last_type!($($T,)+): ?Sized
             {}
         }
 
@@ -71,8 +66,6 @@ macro_rules! tuple_impls {
             $($T)+ @
             #[stable(feature = "rust1", since = "1.0.0")]
             impl<$($T: PartialOrd),+> PartialOrd for ($($T,)+)
-            where
-                last_type!($($T,)+): ?Sized
             {
                 #[inline]
                 fn partial_cmp(&self, other: &($($T,)+)) -> Option<Ordering> {
@@ -101,8 +94,6 @@ macro_rules! tuple_impls {
             $($T)+ @
             #[stable(feature = "rust1", since = "1.0.0")]
             impl<$($T: Ord),+> Ord for ($($T,)+)
-            where
-                last_type!($($T,)+): ?Sized
             {
                 #[inline]
                 fn cmp(&self, other: &($($T,)+)) -> Ordering {
@@ -205,9 +196,4 @@ macro_rules! lexical_cmp {
     ($a:expr, $b:expr) => { ($a).cmp(&$b) };
 }
 
-macro_rules! last_type {
-    ($a:ident,) => { $a };
-    ($a:ident, $($rest_a:ident,)+) => { last_type!($($rest_a,)+) };
-}
-
 tuple_impls!(E D C B A Z Y X W V U T);