From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Tue, 12 Mar 2019 13:43:49 +0000 (+0100)
Subject: Explain the bits of `UndefMask`
X-Git-Url: https://git.lizzy.rs/?a=commitdiff_plain;h=1ae131211be24a337877e6dbcd9b6c52a86b9511;p=rust.git

Explain the bits of `UndefMask`
---

diff --git a/src/librustc/mir/interpret/allocation.rs b/src/librustc/mir/interpret/allocation.rs
index 004804f7c21..2ce9a4a0f20 100644
--- a/src/librustc/mir/interpret/allocation.rs
+++ b/src/librustc/mir/interpret/allocation.rs
@@ -613,6 +613,8 @@ fn deref_mut(&mut self) -> &mut Self::Target {
 
 type Block = u64;
 
+/// A bitmask where each bit refers to the byte with the same index. If the bit is `true`, the byte
+/// is defined. If it is `false` the byte is undefined.
 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
 pub struct UndefMask {
     blocks: Vec<Block>,