use BITS constant

Author: the8472

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

@@ -58,7 +58,7 @@ mod tests;
 const INITIAL_CAPACITY: usize = 7; // 2^3 - 1
 const MINIMUM_CAPACITY: usize = 1; // 2 - 1
 
-const MAXIMUM_ZST_CAPACITY: usize = 1 << (core::mem::size_of::<usize>() * 8 - 1); // Largest possible power of two
+const MAXIMUM_ZST_CAPACITY: usize = 1 << (usize::BITS - 1); // Largest possible power of two
 
 /// A double-ended queue implemented with a growable ring buffer.
 ///