From cb2703945ca3c6c9664a5a9ec606430cb79ba2c8 Mon Sep 17 00:00:00 2001
From: Matthew Jasper <mjjasper1@gmail.com>
Date: Sun, 19 Apr 2020 12:34:00 +0100
Subject: Use min_specialization in liballoc

- Remove a type parameter from `[A]RcFromIter`.
- Remove an implementation of `[A]RcFromIter` that didn't actually
  specialize anything.
- Remove unused implementation of `IsZero` for `Option<&mut T>`.
- Change specializations of `[A]RcEqIdent` to use a marker trait version
of `Eq`.
- Remove `BTreeClone`. I couldn't find a way to make this work with
  `min_specialization`.
- Add `rustc_unsafe_specialization_marker` to `Copy` and `TrustedLen`.
---
 src/liballoc/collections/btree/map.rs | 53 -----------------------------------
 1 file changed, 53 deletions(-)

(limited to 'src/liballoc/collections/btree')

diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index 099687bd6b0..61d2295ba8c 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -215,59 +215,6 @@ impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
             clone_subtree(self.root.as_ref().unwrap().as_ref())
         }
     }
-
-    fn clone_from(&mut self, other: &Self) {
-        BTreeClone::clone_from(self, other);
-    }
-}
-
-trait BTreeClone {
-    fn clone_from(&mut self, other: &Self);
-}
-
-impl<K: Clone, V: Clone> BTreeClone for BTreeMap<K, V> {
-    default fn clone_from(&mut self, other: &Self) {
-        *self = other.clone();
-    }
-}
-
-impl<K: Clone + Ord, V: Clone> BTreeClone for BTreeMap<K, V> {
-    fn clone_from(&mut self, other: &Self) {
-        // This truncates `self` to `other.len()` by calling `split_off` on
-        // the first key after `other.len()` elements if it exists.
-        let split_off_key = if self.len() > other.len() {
-            let diff = self.len() - other.len();
-            if diff <= other.len() {
-                self.iter().nth_back(diff - 1).map(|pair| (*pair.0).clone())
-            } else {
-                self.iter().nth(other.len()).map(|pair| (*pair.0).clone())
-            }
-        } else {
-            None
-        };
-        if let Some(key) = split_off_key {
-            self.split_off(&key);
-        }
-
-        let mut siter = self.range_mut(..);
-        let mut oiter = other.iter();
-        // After truncation, `self` is at most as long as `other` so this loop
-        // replaces every key-value pair in `self`. Since `oiter` is in sorted
-        // order and the structure of the `BTreeMap` stays the same,
-        // the BTree invariants are maintained at the end of the loop.
-        while !siter.is_empty() {
-            if let Some((ok, ov)) = oiter.next() {
-                // SAFETY: This is safe because `siter` is nonempty.
-                let (sk, sv) = unsafe { siter.next_unchecked() };
-                sk.clone_from(ok);
-                sv.clone_from(ov);
-            } else {
-                break;
-            }
-        }
-        // If `other` is longer than `self`, the remaining elements are inserted.
-        self.extend(oiter.map(|(k, v)| ((*k).clone(), (*v).clone())));
-    }
 }
 
 impl<K, Q: ?Sized> super::Recover<Q> for BTreeMap<K, ()>
-- 
cgit 1.4.1-3-g733a5