Revert "Add implementations of last in terms of next_back on a bunch of DoubleEndedIterators."

This reverts commit 3e86cf36b5114f201868bf459934fe346a76a2d4.

14 files changed, 0 insertions, 159 deletions

diff --git a/src/liballoc/collections/binary_heap.rs b/src/liballoc/collections/binary_heap.rs
index c5a0b6e877b..c898f064fd0 100644
--- a/src/liballoc/collections/binary_heap.rs
+++ b/src/liballoc/collections/binary_heap.rs
@@ -1035,11 +1035,6 @@ impl<'a, T> Iterator for Iter<'a, T> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<&'a T> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1095,11 +1090,6 @@ impl<T> Iterator for IntoIter<T> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<T> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1146,11 +1136,6 @@ impl<T> Iterator for Drain<'_, T> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<T> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index 414abb00ef1..6b079fc87cc 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -1193,11 +1193,6 @@ impl<'a, K: 'a, V: 'a> Iterator for Iter<'a, K, V> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         (self.length, Some(self.length))
     }
-
-    #[inline]
-    fn last(mut self) -> Option<(&'a K, &'a V)> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
@@ -1258,11 +1253,6 @@ impl<'a, K: 'a, V: 'a> Iterator for IterMut<'a, K, V> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         (self.length, Some(self.length))
     }
-
-    #[inline]
-    fn last(mut self) -> Option<(&'a K, &'a mut V)> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1369,11 +1359,6 @@ impl<K, V> Iterator for IntoIter<K, V> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         (self.length, Some(self.length))
     }
-
-    #[inline]
-    fn last(mut self) -> Option<(K, V)> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1436,11 +1421,6 @@ impl<'a, K, V> Iterator for Keys<'a, K, V> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.inner.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<&'a K> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1478,11 +1458,6 @@ impl<'a, K, V> Iterator for Values<'a, K, V> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.inner.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<&'a V> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1520,11 +1495,6 @@ impl<'a, K, V> Iterator for Range<'a, K, V> {
             unsafe { Some(self.next_unchecked()) }
         }
     }
-
-    #[inline]
-    fn last(mut self) -> Option<(&'a K, &'a V)> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "map_values_mut", since = "1.10.0")]
@@ -1538,11 +1508,6 @@ impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.inner.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<&'a mut V> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "map_values_mut", since = "1.10.0")]
@@ -1661,11 +1626,6 @@ impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
             unsafe { Some(self.next_unchecked()) }
         }
     }
-
-    #[inline]
-    fn last(mut self) -> Option<(&'a K, &'a mut V)> {
-        self.next_back()
-    }
 }
 
 impl<'a, K, V> RangeMut<'a, K, V> {
diff --git a/src/liballoc/collections/btree/set.rs b/src/liballoc/collections/btree/set.rs
index 6f2467dfd6b..16a96ca19b8 100644
--- a/src/liballoc/collections/btree/set.rs
+++ b/src/liballoc/collections/btree/set.rs
@@ -1019,11 +1019,6 @@ impl<'a, T> Iterator for Iter<'a, T> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<&'a T> {
-        self.next_back()
-    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
@@ -1049,11 +1044,6 @@ impl<T> Iterator for IntoIter<T> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<T> {
-        self.next_back()
-    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> DoubleEndedIterator for IntoIter<T> {
@@ -1083,11 +1073,6 @@ impl<'a, T> Iterator for Range<'a, T> {
     fn next(&mut self) -> Option<&'a T> {
         self.iter.next().map(|(k, _)| k)
     }
-
-    #[inline]
-    fn last(mut self) -> Option<&'a T> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "btree_range", since = "1.17.0")]
diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index e74d37c1c2b..7f7722548f5 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -2385,10 +2385,6 @@ impl Iterator for Drain<'_> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-    #[inline]
-    fn last(mut self) -> Option<char> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
index c0cdffe596b..073d3ab5937 100644
--- a/src/liballoc/vec.rs
+++ b/src/liballoc/vec.rs
@@ -2395,11 +2395,6 @@ impl<T> Iterator for IntoIter<T> {
     fn count(self) -> usize {
         self.len()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<T> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -2519,11 +2514,6 @@ impl<T> Iterator for Drain<'_, T> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<T> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
@@ -2593,10 +2583,6 @@ impl<I: Iterator> Iterator for Splice<'_, I> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.drain.size_hint()
     }
-
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "vec_splice", since = "1.21.0")]
diff --git a/src/libcore/ascii.rs b/src/libcore/ascii.rs
index ddee02ea232..c0ab364380f 100644
--- a/src/libcore/ascii.rs
+++ b/src/libcore/ascii.rs
@@ -117,8 +117,6 @@ impl Iterator for EscapeDefault {
     type Item = u8;
     fn next(&mut self) -> Option<u8> { self.range.next().map(|i| self.data[i]) }
     fn size_hint(&self) -> (usize, Option<usize>) { self.range.size_hint() }
-    #[inline]
-    fn last(mut self) -> Option<u8> { self.next_back() }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl DoubleEndedIterator for EscapeDefault {
diff --git a/src/libcore/iter/adapters/mod.rs b/src/libcore/iter/adapters/mod.rs
index 64e588f65b4..518442efe74 100644
--- a/src/libcore/iter/adapters/mod.rs
+++ b/src/libcore/iter/adapters/mod.rs
@@ -73,11 +73,6 @@ impl<I> Iterator for Rev<I> where I: DoubleEndedIterator {
     {
         self.iter.position(predicate)
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/src/libcore/slice/mod.rs b/src/libcore/slice/mod.rs
index d06d107d32a..50d2ba0d3ef 100644
--- a/src/libcore/slice/mod.rs
+++ b/src/libcore/slice/mod.rs
@@ -3547,11 +3547,6 @@ impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
             (1, Some(self.v.len() + 1))
         }
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -3650,11 +3645,6 @@ impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
             (1, Some(self.v.len() + 1))
         }
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -3720,11 +3710,6 @@ impl<'a, T, P> Iterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.inner.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "slice_rsplit", since = "1.27.0")]
@@ -3789,11 +3774,6 @@ impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.inner.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "slice_rsplit", since = "1.27.0")]
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index 0e8a2da3c11..ef4bd83cbc5 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -1333,11 +1333,6 @@ impl<'a> Iterator for Lines<'a> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.0.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1384,11 +1379,6 @@ impl<'a> Iterator for LinesAny<'a> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.0.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -4231,11 +4221,6 @@ impl<'a> Iterator for SplitWhitespace<'a> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.inner.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "split_whitespace", since = "1.1.0")]
@@ -4262,11 +4247,6 @@ impl<'a> Iterator for SplitAsciiWhitespace<'a> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.inner.size_hint()
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
diff --git a/src/libstd/env.rs b/src/libstd/env.rs
index 260624a8bd8..9058ea93d6d 100644
--- a/src/libstd/env.rs
+++ b/src/libstd/env.rs
@@ -746,10 +746,6 @@ impl Iterator for Args {
         self.inner.next().map(|s| s.into_string().unwrap())
     }
     fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
-    #[inline]
-    fn last(mut self) -> Option<String> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "env", since = "1.0.0")]
@@ -785,8 +781,6 @@ impl Iterator for ArgsOs {
     type Item = OsString;
     fn next(&mut self) -> Option<OsString> { self.inner.next() }
     fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
-    #[inline]
-    fn last(mut self) -> Option<OsString> { self.next_back() }
 }
 
 #[stable(feature = "env", since = "1.0.0")]
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 59f9e439add..126bc3754da 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -888,11 +888,6 @@ impl<'a> Iterator for Iter<'a> {
     fn next(&mut self) -> Option<&'a OsStr> {
         self.inner.next().map(Component::as_os_str)
     }
-
-    #[inline]
-    fn last(mut self) -> Option<&'a OsStr> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -956,11 +951,6 @@ impl<'a> Iterator for Components<'a> {
         }
         None
     }
-
-    #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.next_back()
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/src/libstd/sys/unix/args.rs b/src/libstd/sys/unix/args.rs
index 6ba947d4598..3b4de56f2c9 100644
--- a/src/libstd/sys/unix/args.rs
+++ b/src/libstd/sys/unix/args.rs
@@ -35,8 +35,6 @@ impl Iterator for Args {
     type Item = OsString;
     fn next(&mut self) -> Option<OsString> { self.iter.next() }
     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
-    #[inline]
-    fn last(mut self) -> Option<OsString> { self.next_back() }
 }
 
 impl ExactSizeIterator for Args {
diff --git a/src/libstd/sys/wasm/args.rs b/src/libstd/sys/wasm/args.rs
index 6766099c1ec..b3c77b86995 100644
--- a/src/libstd/sys/wasm/args.rs
+++ b/src/libstd/sys/wasm/args.rs
@@ -37,10 +37,6 @@ impl Iterator for Args {
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
-    #[inline]
-    fn last(mut self) -> Option<OsString> {
-        self.next_back()
-    }
 }
 
 impl ExactSizeIterator for Args {
diff --git a/src/libstd/sys/windows/args.rs b/src/libstd/sys/windows/args.rs
index 744d7ec59d3..b04bb484eed 100644
--- a/src/libstd/sys/windows/args.rs
+++ b/src/libstd/sys/windows/args.rs
@@ -181,8 +181,6 @@ impl Iterator for Args {
     type Item = OsString;
     fn next(&mut self) -> Option<OsString> { self.parsed_args_list.next() }
     fn size_hint(&self) -> (usize, Option<usize>) { self.parsed_args_list.size_hint() }
-    #[inline]
-    fn last(mut self) -> Option<OsString> { self.next_back() }
 }
 
 impl DoubleEndedIterator for Args {