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();
   |       ~~~~~~
```

#59450

1 files changed, 5 insertions, 0 deletions

diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index bcba6525fda..c35bab5ef66 100644
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/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;