const version of try_from_array_len, and some missing inlines

src/arrayvec.rs

@@ -1071,6 +1071,7 @@ impl<A: Array> ArrayVec<A> {
   /// If the given length is greater than the capacity of the array this will
   /// error, and you'll get the array back in the `Err`.
   #[inline]
+  #[cfg(not(feature = "latest_stable_rust"))]
   pub fn try_from_array_len(data: A, len: usize) -> Result<Self, A> {
     /* Note(Soveu): Should we allow A::CAPACITY > u16::MAX for now? */
     if len <= A::CAPACITY {
@@ -1079,6 +1080,26 @@ impl<A: Array> ArrayVec<A> {
       Err(data)
     }
   }
+
+  /// Wraps an array, using the given length as the starting length.
+  ///
+  /// If you want to use the whole length of the array, you can just use the
+  /// `From` impl.
+  ///
+  /// ## Failure
+  ///
+  /// If the given length is greater than the capacity of the array this will
+  /// error, and you'll get the array back in the `Err`.
+  #[inline]
+  #[cfg(feature = "latest_stable_rust")]
+  pub const fn try_from_array_len(data: A, len: usize) -> Result<Self, A> {
+    /* Note(Soveu): Should we allow A::CAPACITY > u16::MAX for now? */
+    if len <= A::CAPACITY {
+      Ok(Self { data, len: len as u16 })
+    } else {
+      Err(data)
+    }
+  }
 }
 
 impl<A> ArrayVec<A> {
@@ -1883,6 +1904,7 @@ impl<A: Array> ArrayVec<A> {
   /// assert_eq!(v, &[1, 2, 3]);
   /// assert_eq!(v.capacity(), 13);
   /// ```
+  #[inline]
   #[cfg(feature = "rustc_1_57")]
   pub fn try_drain_to_vec_and_reserve(
     &mut self, n: usize,
@@ -1925,6 +1947,7 @@ impl<A: Array> ArrayVec<A> {
   /// // Vec may reserve more than necessary in order to prevent more future allocations.
   /// assert!(v.capacity() >= 3);
   /// ```
+  #[inline]
   #[cfg(feature = "rustc_1_57")]
   pub fn try_drain_to_vec(&mut self) -> Result<Vec<A::Item>, TryReserveError> {
     self.try_drain_to_vec_and_reserve(0)