1 files changed, 45 insertions, 0 deletions
diff --git a/tests/ui/nll/polonius/iterating-updating-cursor-issue-57165.rs b/tests/ui/nll/polonius/iterating-updating-cursor-issue-57165.rs
new file mode 100644
index 00000000000..9670fc77e6f
--- /dev/null
+++ b/tests/ui/nll/polonius/iterating-updating-cursor-issue-57165.rs
@@ -0,0 +1,45 @@
+#![crate_type = "lib"]
+
+// An example from #57165 of the linked-list cursor-like pattern of #46859/#48001, where the
+// polonius alpha analysis shows the same imprecision as NLLs, unlike the datalog implementation.
+
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: nll polonius legacy
+//@ [nll] known-bug: #57165
+//@ [polonius] known-bug: #57165
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] check-pass
+//@ [legacy] compile-flags: -Z polonius=legacy
+
+struct X {
+    next: Option<Box<X>>,
+}
+
+fn no_control_flow() {
+    let mut b = Some(Box::new(X { next: None }));
+    let mut p = &mut b;
+    while let Some(now) = p {
+        p = &mut now.next;
+    }
+}
+
+// NLLs and polonius alpha fail here
+fn conditional() {
+    let mut b = Some(Box::new(X { next: None }));
+    let mut p = &mut b;
+    while let Some(now) = p {
+        if true {
+            p = &mut now.next;
+        }
+    }
+}
+
+fn conditional_with_indirection() {
+    let mut b = Some(Box::new(X { next: None }));
+    let mut p = &mut b;
+    while let Some(now) = p {
+        if true {
+            p = &mut p.as_mut().unwrap().next;
+        }
+    }
+}