Make zero-capacity ArrayVec a zero-sized type.

2017-09-26 11:55:00 -04:00
parent 16aabf7c2c
commit 55bedc922a
2 changed files with 24 additions and 3 deletions
@@ -139,6 +139,11 @@ fn test_compact_size() {
    println!("{}", mem::size_of::<ByteArray>());
    assert!(mem::size_of::<ByteArray>() <= 8);

+    // 1 enum tag + 1 drop flag
+    type EmptyArray = ArrayVec<[u8; 0]>;
+    println!("{}", mem::size_of::<EmptyArray>());
+    assert!(mem::size_of::<EmptyArray>() <= 2);
+
    // 12 element size + 1 enum tag + 3 padding + 1 len + 1 drop flag + 2 padding
    type QuadArray = ArrayVec<[u32; 3]>;
    println!("{}", mem::size_of::<QuadArray>());