Add rustc_confusables annotations to some stdlib APIs

Help with common API confusion, like asking for `push` when the data structure really has `append`.

```
error[E0599]: no method named `size` found for struct `Vec<{integer}>` in the current scope
  --> $DIR/rustc_confusables_std_cases.rs:17:7
   |
LL |     x.size();
   |       ^^^^
   |
help: you might have meant to use `len`
   |
LL |     x.len();
   |       ~~~
help: there is a method with a similar name
   |
LL |     x.resize();
   |       ~~~~~~
```

rust-lang#59450

Author: estebank

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -1113,32 +1113,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         err.note(format!(
                             "the {item_kind} was found for\n{type_candidates}{additional_types}"
                         ));
-                    } else {
-                        'outer: for inherent_impl_did in
-                            self.tcx.inherent_impls(adt.did()).into_iter().flatten()
-                        {
-                            for inherent_method in
-                                self.tcx.associated_items(inherent_impl_did).in_definition_order()
-                            {
-                                if let Some(attr) = self
-                                    .tcx
-                                    .get_attr(inherent_method.def_id, sym::rustc_confusables)
-                                    && let Some(candidates) = parse_confusables(attr)
-                                    && candidates.contains(&item_name.name)
-                                {
-                                    err.span_suggestion_verbose(
-                                        item_name.span,
-                                        format!(
-                                            "you might have meant to use `{}`",
-                                            inherent_method.name
-                                        ),
-                                        inherent_method.name,
-                                        Applicability::MaybeIncorrect,
-                                    );
-                                    break 'outer;
-                                }
-                            }
-                        }
                     }
                 }
             } else {
@@ -1164,6 +1138,34 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             label_span_not_found(&mut err);
         }
 
+        let mut confusable_suggested = None;
+        if let ty::Adt(adt, _) = rcvr_ty.kind() {
+            'outer: for inherent_impl_did in
+                self.tcx.inherent_impls(adt.did()).into_iter().flatten()
+            {
+                for inherent_method in
+                    self.tcx.associated_items(inherent_impl_did).in_definition_order()
+                {
+                    if let Some(attr) =
+                        self.tcx.get_attr(inherent_method.def_id, sym::rustc_confusables)
+                        && let Some(candidates) = parse_confusables(attr)
+                        && candidates.contains(&item_name.name)
+                    {
+                        {
+                            err.span_suggestion_verbose(
+                                item_name.span,
+                                format!("you might have meant to use `{}`", inherent_method.name),
+                                inherent_method.name,
+                                Applicability::MaybeIncorrect,
+                            );
+                            confusable_suggested = Some(inherent_method.name);
+                            break 'outer;
+                        }
+                    }
+                }
+            }
+        }
+
         // Don't suggest (for example) `expr.field.clone()` if `expr.clone()`
         // can't be called due to `typeof(expr): Clone` not holding.
         if unsatisfied_predicates.is_empty() {
@@ -1265,7 +1267,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         } else if let Some(similar_candidate) = similar_candidate {
             // Don't emit a suggestion if we found an actual method
             // that had unsatisfied trait bounds
-            if unsatisfied_predicates.is_empty() {
+            if unsatisfied_predicates.is_empty()
+                // ...or if we already suggested that name because of `rustc_confusable` annotation.
+                && Some(similar_candidate.name) != confusable_suggested
+            {
                 let def_kind = similar_candidate.kind.as_def_kind();
                 // Methods are defined within the context of a struct and their first parameter is always self,
                 // which represents the instance of the struct the method is being called on

library/alloc/src/collections/binary_heap/mod.rs

@@ -607,6 +607,7 @@ impl<T: Ord, A: Allocator> BinaryHeap<T, A> {
     /// occurs when capacity is exhausted and needs a resize. The resize cost
     /// has been amortized in the previous figures.
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("append", "put")]
     pub fn push(&mut self, item: T) {
         let old_len = self.len();
         self.data.push(item);
@@ -1264,6 +1265,7 @@ impl<T, A: Allocator> BinaryHeap<T, A> {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("length", "size")]
     pub fn len(&self) -> usize {
         self.data.len()
     }

library/alloc/src/collections/btree/map.rs

@@ -979,6 +979,7 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
     /// assert_eq!(map[&37], "c");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push", "put", "set")]
     pub fn insert(&mut self, key: K, value: V) -> Option<V>
     where
         K: Ord,
@@ -1041,6 +1042,7 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
     /// assert_eq!(map.remove(&1), None);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("delete", "take")]
     pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V>
     where
         K: Borrow<Q> + Ord,
@@ -2495,6 +2497,7 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
         issue = "71835",
         implied_by = "const_btree_new"
     )]
+    #[rustc_confusables("length", "size")]
     pub const fn len(&self) -> usize {
         self.length
     }

library/alloc/src/collections/btree/map/entry.rs

@@ -347,6 +347,7 @@ impl<'a, K: Ord, V, A: Allocator + Clone> VacantEntry<'a, K, V, A> {
     /// assert_eq!(map["poneyland"], 37);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push", "put")]
     pub fn insert(mut self, value: V) -> &'a mut V {
         let out_ptr = match self.handle {
             None => {
@@ -524,6 +525,7 @@ impl<'a, K: Ord, V, A: Allocator + Clone> OccupiedEntry<'a, K, V, A> {
     /// assert_eq!(map["poneyland"], 15);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push", "put")]
     pub fn insert(&mut self, value: V) -> V {
         mem::replace(self.get_mut(), value)
     }
@@ -546,6 +548,7 @@ impl<'a, K: Ord, V, A: Allocator + Clone> OccupiedEntry<'a, K, V, A> {
     /// // println!("{}", map["poneyland"]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("delete", "take")]
     pub fn remove(self) -> V {
         self.remove_kv().1
     }

library/alloc/src/collections/btree/set.rs

@@ -790,6 +790,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
     /// ```
     #[must_use]
     #[stable(feature = "map_first_last", since = "1.66.0")]
+    #[rustc_confusables("front")]
     pub fn first(&self) -> Option<&T>
     where
         T: Ord,
@@ -816,6 +817,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
     /// ```
     #[must_use]
     #[stable(feature = "map_first_last", since = "1.66.0")]
+    #[rustc_confusables("back")]
     pub fn last(&self) -> Option<&T>
     where
         T: Ord,
@@ -896,6 +898,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
     /// assert_eq!(set.len(), 1);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push", "put")]
     pub fn insert(&mut self, value: T) -> bool
     where
         T: Ord,
@@ -919,6 +922,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
     /// assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);
     /// ```
     #[stable(feature = "set_recovery", since = "1.9.0")]
+    #[rustc_confusables("swap")]
     pub fn replace(&mut self, value: T) -> Option<T>
     where
         T: Ord,
@@ -1152,6 +1156,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
         issue = "71835",
         implied_by = "const_btree_new"
     )]
+    #[rustc_confusables("length", "size")]
     pub const fn len(&self) -> usize {
         self.map.len()
     }

library/alloc/src/collections/linked_list.rs

@@ -656,6 +656,7 @@ impl<T, A: Allocator> LinkedList<T, A> {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("length", "size")]
     pub fn len(&self) -> usize {
         self.len
     }
@@ -740,6 +741,7 @@ impl<T, A: Allocator> LinkedList<T, A> {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("first")]
     pub fn front(&self) -> Option<&T> {
         unsafe { self.head.as_ref().map(|node| &node.as_ref().element) }
     }
@@ -890,6 +892,7 @@ impl<T, A: Allocator> LinkedList<T, A> {
     /// assert_eq!(3, *d.back().unwrap());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push", "append")]
     pub fn push_back(&mut self, elt: T) {
         let node = Box::new_in(Node::new(elt), &self.alloc);
         let node_ptr = NonNull::from(Box::leak(node));
@@ -1004,6 +1007,7 @@ impl<T, A: Allocator> LinkedList<T, A> {
     /// assert_eq!(d.remove(0), 1);
     /// ```
     #[unstable(feature = "linked_list_remove", issue = "69210")]
+    #[rustc_confusables("delete", "take")]
     pub fn remove(&mut self, at: usize) -> T {
         let len = self.len();
         assert!(at < len, "Cannot remove at an index outside of the list bounds");
@@ -1478,6 +1482,7 @@ impl<'a, T, A: Allocator> Cursor<'a, T, A> {
     /// or None if the list is empty.
     #[must_use]
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
+    #[rustc_confusables("first")]
     pub fn front(&self) -> Option<&'a T> {
         self.list.front()
     }
@@ -1486,6 +1491,7 @@ impl<'a, T, A: Allocator> Cursor<'a, T, A> {
     /// or None if the list is empty.
     #[must_use]
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
+    #[rustc_confusables("last")]
     pub fn back(&self) -> Option<&'a T> {
         self.list.back()
     }
@@ -1788,6 +1794,7 @@ impl<'a, T, A: Allocator> CursorMut<'a, T, A> {
     ///
     /// This operation should compute in *O*(1) time.
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
+    #[rustc_confusables("push", "append")]
     pub fn push_back(&mut self, elt: T) {
         // Safety: We know that `push_back` does not change the position in
         // memory of other nodes. This ensures that `self.current` remains
@@ -1834,6 +1841,7 @@ impl<'a, T, A: Allocator> CursorMut<'a, T, A> {
     ///
     /// This operation should compute in *O*(1) time.
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
+    #[rustc_confusables("pop")]
     pub fn pop_back(&mut self) -> Option<T> {
         if self.list.is_empty() {
             None
@@ -1854,6 +1862,7 @@ impl<'a, T, A: Allocator> CursorMut<'a, T, A> {
     /// or None if the list is empty.
     #[must_use]
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
+    #[rustc_confusables("first")]
     pub fn front(&self) -> Option<&T> {
         self.list.front()
     }
@@ -1870,6 +1879,7 @@ impl<'a, T, A: Allocator> CursorMut<'a, T, A> {
     /// or None if the list is empty.
     #[must_use]
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
+    #[rustc_confusables("last")]
     pub fn back(&self) -> Option<&T> {
         self.list.back()
     }

library/alloc/src/collections/vec_deque/mod.rs

@@ -1209,6 +1209,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(deque.len(), 1);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("length", "size")]
     pub fn len(&self) -> usize {
         self.len
     }
@@ -1491,6 +1492,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(d.front(), Some(&1));
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("first")]
     pub fn front(&self) -> Option<&T> {
         self.get(0)
     }
@@ -1535,6 +1537,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(d.back(), Some(&2));
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("last")]
     pub fn back(&self) -> Option<&T> {
         self.get(self.len.wrapping_sub(1))
     }
@@ -1654,6 +1657,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(3, *buf.back().unwrap());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push", "put", "append")]
     pub fn push_back(&mut self, value: T) {
         if self.is_full() {
             self.grow();
@@ -1813,6 +1817,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(buf, [1, 3]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("delete", "take")]
     pub fn remove(&mut self, index: usize) -> Option<T> {
         if self.len <= index {
             return None;

library/alloc/src/string.rs

@@ -1445,6 +1445,7 @@ impl String {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("delete", "take")]
     pub fn remove(&mut self, idx: usize) -> char {
         let ch = match self[idx..].chars().next() {
             Some(ch) => ch,
@@ -1639,6 +1640,7 @@ impl String {
     #[cfg(not(no_global_oom_handling))]
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("set")]
     pub fn insert(&mut self, idx: usize, ch: char) {
         assert!(self.is_char_boundary(idx));
         let mut bits = [0; 4];
@@ -1738,6 +1740,7 @@ impl String {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("length", "size")]
     pub fn len(&self) -> usize {
         self.vec.len()
     }

library/alloc/src/vec/mod.rs

@@ -1554,6 +1554,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[track_caller]
+    #[rustc_confusables("delete", "take")]
     pub fn remove(&mut self, index: usize) -> T {
         #[cold]
         #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
@@ -1915,6 +1916,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[cfg(not(no_global_oom_handling))]
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push_back", "put", "append")]
     pub fn push(&mut self, value: T) {
         // This will panic or abort if we would allocate > isize::MAX bytes
         // or if the length increment would overflow for zero-sized types.
@@ -2141,6 +2143,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("length", "size")]
     pub fn len(&self) -> usize {
         self.len
     }

library/core/src/cell.rs

@@ -471,6 +471,7 @@ impl<T> Cell<T> {
     /// ```
     #[inline]
     #[stable(feature = "move_cell", since = "1.17.0")]
+    #[rustc_confusables("swap")]
     pub fn replace(&self, val: T) -> T {
         // SAFETY: This can cause data races if called from a separate thread,
         // but `Cell` is `!Sync` so this won't happen.
@@ -862,6 +863,7 @@ impl<T> RefCell<T> {
     #[inline]
     #[stable(feature = "refcell_replace", since = "1.24.0")]
     #[track_caller]
+    #[rustc_confusables("swap")]
     pub fn replace(&self, t: T) -> T {
         mem::replace(&mut *self.borrow_mut(), t)
     }

library/proc_macro/src/bridge/scoped_cell.rs

@@ -43,6 +43,7 @@ impl<T: LambdaL> ScopedCell<T> {
     /// running `f`, which gets the old value, mutably.
     /// The old value will be restored after `f` exits, even
     /// by panic, including modifications made to it by `f`.
+    #[rustc_confusables("swap")]
     pub fn replace<'a, R>(
         &self,
         replacement: <T as ApplyL<'a>>::Out,

library/std/src/collections/hash/map.rs

@@ -1101,6 +1101,7 @@ where
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("push", "append")]
     pub fn insert(&mut self, k: K, v: V) -> Option<V> {
         self.base.insert(k, v)
     }
@@ -1155,6 +1156,7 @@ where
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("delete", "take")]
     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
     where
         K: Borrow<Q>,