From 50c00a93016ee8987dc75d201fd8c9ed5e763441 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 29 Sep 2018 09:51:38 +0200
Subject: [PATCH] expand comment

---
 src/librustc_mir/interpret/memory.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index ab5e37a1d450..8b11a8ec4971 100644
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -759,6 +759,8 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
         // SAFE: The above indexing would have panicked if there weren't at least `size` bytes
         // behind `src` and `dest`. Also, we use the overlapping-safe `ptr::copy` if `src` and
         // `dest` could possibly overlap.
+        // The pointers above remain valid even if the `HashMap` table moved around because they
+        // point into the `Vec` storing the bytes.
         unsafe {
             assert_eq!(size.bytes() as usize as u64, size.bytes());
             if src.alloc_id == dest.alloc_id {