Add regression test for old NLL ICE

1 files changed, 20 insertions, 0 deletions

diff --git a/src/test/ui/issues/issue-51770.rs b/src/test/ui/issues/issue-51770.rs
new file mode 100644
index 00000000000..bcb37a5f4ff
--- /dev/null
+++ b/src/test/ui/issues/issue-51770.rs
@@ -0,0 +1,20 @@
+// check-pass
+
+#![crate_type = "lib"]
+
+// In an older version, when NLL was still a feature, the following previously did not compile
+// #![feature(nll)]
+
+use std::ops::Index;
+
+pub struct Test<T> {
+    a: T,
+}
+
+impl<T> Index<usize> for Test<T> {
+    type Output = T;
+
+    fn index(&self, _index: usize) -> &Self::Output {
+        &self.a
+    }
+}