1 files changed, 34 insertions, 0 deletions

diff --git a/tests/ui/issues/issue-3979.rs b/tests/ui/issues/issue-3979.rs
new file mode 100644
index 00000000000..72949d8c757
--- /dev/null
+++ b/tests/ui/issues/issue-3979.rs
@@ -0,0 +1,34 @@
+// run-pass
+#![allow(dead_code)]
+#![allow(non_snake_case)]
+
+trait Positioned {
+  fn SetX(&mut self, _: isize);
+  fn X(&self) -> isize;
+}
+
+trait Movable: Positioned {
+  fn translate(&mut self, dx: isize) {
+    let x = self.X();
+    self.SetX(x + dx);
+  }
+}
+
+struct Point { x: isize, y: isize }
+
+impl Positioned for Point {
+    fn SetX(&mut self, x: isize) {
+        self.x = x;
+    }
+    fn X(&self) -> isize {
+        self.x
+    }
+}
+
+impl Movable for Point {}
+
+pub fn main() {
+    let mut p = Point{ x: 1, y: 2};
+    p.translate(3);
+    assert_eq!(p.X(), 4);
+}