core: Change `BorrowedCursor::written`'s origin

This enable removing the `start` field, so `BorrowedCursor` fits in a
single register. Because `written` is almost always used in difference
with another call, this changes nothing else in practice.

1 files changed, 1 insertions, 1 deletions

diff --git a/library/coretests/tests/io/borrowed_buf.rs b/library/coretests/tests/io/borrowed_buf.rs
index 60829109d50..869fc31fee9 100644
--- a/library/coretests/tests/io/borrowed_buf.rs
+++ b/library/coretests/tests/io/borrowed_buf.rs
@@ -124,7 +124,7 @@ fn reborrow_written() {
     assert_eq!(cursor2.written(), 32);
     assert_eq!(cursor.written(), 32);
 
-    assert_eq!(buf.unfilled().written(), 0);
+    assert_eq!(buf.unfilled().written(), 32);
     assert_eq!(buf.init_len(), 32);
     assert_eq!(buf.filled().len(), 32);
     let filled = buf.filled();