Rollup merge of #80430 - xfix:add-length-as-doc-alias, r=steveklabnik

Add "length" as doc alias to len methods

Currently when searching for `length` there are no results: https://doc.rust-lang.org/std/?search=length. This makes `len` methods appear when searching for `length`.

Author: m-ou-se

library/alloc/src/collections/binary_heap.rs

@@ -915,6 +915,7 @@ impl<T> BinaryHeap<T> {
     ///
     /// assert_eq!(heap.len(), 2);
     /// ```
+    #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.data.len()

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

@@ -2132,6 +2132,7 @@ impl<K, V> BTreeMap<K, V> {
     /// a.insert(1, "a");
     /// assert_eq!(a.len(), 1);
     /// ```
+    #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
     pub const fn len(&self) -> usize {

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

@@ -975,6 +975,7 @@ impl<T> BTreeSet<T> {
     /// v.insert(1);
     /// assert_eq!(v.len(), 1);
     /// ```
+    #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
     pub const fn len(&self) -> usize {

library/alloc/src/collections/linked_list.rs

@@ -593,6 +593,7 @@ impl<T> LinkedList<T> {
     /// dl.push_back(3);
     /// assert_eq!(dl.len(), 3);
     /// ```
+    #[doc(alias = "length")]
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {

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

@@ -1038,6 +1038,7 @@ impl<T> VecDeque<T> {
     /// v.push_back(1);
     /// assert_eq!(v.len(), 1);
     /// ```
+    #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         count(self.tail, self.head, self.cap())

library/alloc/src/string.rs

@@ -1388,6 +1388,7 @@ impl String {
     /// assert_eq!(fancy_f.len(), 4);
     /// assert_eq!(fancy_f.chars().count(), 3);
     /// ```
+    #[doc(alias = "length")]
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {

library/alloc/src/vec.rs

@@ -1559,6 +1559,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// let a = vec![1, 2, 3];
     /// assert_eq!(a.len(), 3);
     /// ```
+    #[doc(alias = "length")]
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {

library/core/src/iter/traits/exact_size.rs

@@ -91,6 +91,7 @@ pub trait ExactSizeIterator: Iterator {
     ///
     /// assert_eq!(5, five.len());
     /// ```
+    #[doc(alias = "length")]
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     fn len(&self) -> usize {

library/core/src/slice/mod.rs

@@ -84,6 +84,7 @@ impl<T> [T] {
     /// let a = [1, 2, 3];
     /// assert_eq!(a.len(), 3);
     /// ```
+    #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_slice_len", since = "1.32.0")]
     #[inline]

library/core/src/str/mod.rs

@@ -138,6 +138,7 @@ impl str {
     /// assert_eq!("ƒoo".len(), 4); // fancy f!
     /// assert_eq!("ƒoo".chars().count(), 3);
     /// ```
+    #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_str_len", since = "1.32.0")]
     #[inline]