1 files changed, 36 insertions, 0 deletions
diff --git a/src/test/ui/borrowck/borrowck-overloaded-index-and-overloaded-deref.rs b/src/test/ui/borrowck/borrowck-overloaded-index-and-overloaded-deref.rs
new file mode 100644
index 000000000..0e3e01a93
--- /dev/null
+++ b/src/test/ui/borrowck/borrowck-overloaded-index-and-overloaded-deref.rs
@@ -0,0 +1,36 @@
+// Check that we properly record borrows when we are doing an
+// overloaded, autoderef of a value obtained via an overloaded index
+// operator. The accounting of the all the implicit things going on
+// here is rather subtle. Issue #20232.
+
+use std::ops::{Deref, Index};
+
+struct MyVec<T> { x: T }
+
+impl<T> Index<usize> for MyVec<T> {
+    type Output = T;
+    fn index(&self, _: usize) -> &T {
+        &self.x
+    }
+}
+
+struct MyPtr<T> { x: T }
+
+impl<T> Deref for MyPtr<T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        &self.x
+    }
+}
+
+struct Foo { f: usize }
+
+fn main() {
+    let mut v = MyVec { x: MyPtr { x: Foo { f: 22 } } };
+    let i = &v[0].f;
+    v = MyVec { x: MyPtr { x: Foo { f: 23 } } };
+    //~^ ERROR cannot assign to `v` because it is borrowed
+    read(*i);
+}
+
+fn read(_: usize) { }