From d9d5c59ef81038d7b50f61c4250a132c2f5dc91c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20F=C3=A4rber?= <01mf02@gmail.com>
Date: Tue, 20 May 2025 14:52:05 +0200
Subject: [PATCH] Guarantee address in `slice()` for empty slices. (#780)

---
 src/bytes.rs        |  2 +-
 tests/test_bytes.rs | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/bytes.rs b/src/bytes.rs
index e2c187c..5c2ca18 100644
--- a/src/bytes.rs
+++ b/src/bytes.rs
@@ -401,7 +401,7 @@ impl Bytes {
         );
 
         if end == begin {
-            return Bytes::new();
+            return Bytes::new_empty_with_ptr(self.ptr.wrapping_add(begin));
         }
 
         let mut ret = self.clone();
diff --git a/tests/test_bytes.rs b/tests/test_bytes.rs
index f36abaa..e147783 100644
--- a/tests/test_bytes.rs
+++ b/tests/test_bytes.rs
@@ -1421,6 +1421,26 @@ fn try_reclaim_arc() {
     assert_eq!(true, buf.try_reclaim(6));
 }
 
+#[test]
+fn slice_empty_addr() {
+    let buf = Bytes::from(vec![0; 1024]);
+
+    let ptr_start = buf.as_ptr();
+    let ptr_end = ptr_start.wrapping_add(1024);
+
+    let empty_end = buf.slice(1024..);
+    assert_eq!(empty_end.len(), 0);
+    assert_eq!(empty_end.as_ptr(), ptr_end);
+
+    let empty_start = buf.slice(..0);
+    assert_eq!(empty_start.len(), 0);
+    assert_eq!(empty_start.as_ptr(), ptr_start);
+
+    // Is miri happy about the provenance?
+    let _ = &empty_end[..];
+    let _ = &empty_start[..];
+}
+
 #[test]
 fn split_off_empty_addr() {
     let mut buf = Bytes::from(vec![0; 1024]);