Rollup merge of #123806 - joboet:advanced_overflow, r=Amanieu

Panic on overflow in `BorrowedCursor::advance`

Passing `usize::MAX` to `advance` clearly isn't correct, but the current assertion fails to detect this when overflow checks are disabled. This isn't unsound, but should probably be fixed regardless.

1 files changed, 9 insertions, 0 deletions

diff --git a/library/std/src/io/tests.rs b/library/std/src/io/tests.rs
index eb5d5988768..090a091b09a 100644
--- a/library/std/src/io/tests.rs
+++ b/library/std/src/io/tests.rs
@@ -210,6 +210,15 @@ fn read_buf_exact() {
 }
 
 #[test]
+#[should_panic]
+fn borrowed_cursor_advance_overflow() {
+    let mut buf = [0; 512];
+    let mut buf = BorrowedBuf::from(&mut buf[..]);
+    buf.unfilled().advance(1);
+    buf.unfilled().advance(usize::MAX);
+}
+
+#[test]
 fn take_eof() {
     struct R;