Auto merge of #56403 - ljedrz:inline_len_and_is_empty, r=<try>

Inline len and is_empty in collections

Is there any reason not to? All of these are trivial and heavily utilized.

src/liballoc/collections/binary_heap.rs

@@ -721,6 +721,7 @@ impl<T: Ord> BinaryHeap<T> {
     ///
     /// assert_eq!(heap.len(), 2);
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.data.len()
@@ -744,6 +745,7 @@ impl<T: Ord> BinaryHeap<T> {
     ///
     /// assert!(!heap.is_empty());
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.len() == 0

src/liballoc/collections/btree/map.rs

@@ -2074,6 +2074,7 @@ impl<K, V> BTreeMap<K, V> {
     /// a.insert(1, "a");
     /// assert_eq!(a.len(), 1);
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.length
@@ -2093,6 +2094,7 @@ impl<K, V> BTreeMap<K, V> {
     /// a.insert(1, "a");
     /// assert!(!a.is_empty());
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.len() == 0

src/liballoc/collections/btree/set.rs

@@ -729,6 +729,7 @@ impl<T> BTreeSet<T> {
     /// v.insert(1);
     /// assert_eq!(v.len(), 1);
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.map.len()
@@ -746,6 +747,7 @@ impl<T> BTreeSet<T> {
     /// v.insert(1);
     /// assert!(!v.is_empty());
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.len() == 0

src/liballoc/collections/vec_deque.rs

@@ -932,6 +932,7 @@ impl<T> VecDeque<T> {
     /// v.push_front(1);
     /// assert!(!v.is_empty());
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.tail == self.head

src/liballoc/vec.rs

@@ -1180,6 +1180,7 @@ impl<T> Vec<T> {
     /// v.push(1);
     /// assert!(!v.is_empty());
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.len() == 0

src/libstd/collections/hash/map.rs

@@ -1215,6 +1215,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// a.insert(1, "a");
     /// assert_eq!(a.len(), 1);
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.table.size()

src/libstd/collections/hash/set.rs

@@ -461,6 +461,7 @@ impl<T, S> HashSet<T, S>
     /// v.insert(1);
     /// assert_eq!(v.len(), 1);
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn len(&self) -> usize {
         self.map.len()
@@ -478,6 +479,7 @@ impl<T, S> HashSet<T, S>
     /// v.insert(1);
     /// assert!(!v.is_empty());
     /// ```
+    #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_empty(&self) -> bool {
         self.map.is_empty()

src/libstd/collections/hash/table.rs

@@ -776,6 +776,7 @@ impl<K, V> RawTable<K, V> {
 
     /// The number of elements ever `put` in the hashtable, minus the number
     /// of elements ever `take`n.
+    #[inline]
     pub fn size(&self) -> usize {
         self.size
     }