1 files changed, 24 insertions, 0 deletions
diff --git a/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.rs b/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.rs
new file mode 100644
index 000000000..54ab9f0ad
--- /dev/null
+++ b/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.rs
@@ -0,0 +1,24 @@
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub struct Foo {
+}
+
+impl Foo {
+    fn get(&self) -> Option<&Result<String, String>> {
+        None
+    }
+
+    fn mutate(&mut self) { }
+}
+
+fn main() {
+    let mut foo = Foo { };
+
+    // foo.get() returns type Option<&Result<String, String>>, so
+    // using `string` keeps borrow of `foo` alive. Hence calling
+    // `foo.mutate()` should be an error.
+    while let Some(Ok(string)) = foo.get() {
+        foo.mutate();
+        //~^ ERROR cannot borrow `foo` as mutable
+        println!("foo={:?}", *string);
+    }
+}