1 files changed, 36 insertions, 0 deletions

diff --git a/tests/ui/issues/issue-3979-generics.rs b/tests/ui/issues/issue-3979-generics.rs
new file mode 100644
index 000000000..519de1cad
--- /dev/null
+++ b/tests/ui/issues/issue-3979-generics.rs
@@ -0,0 +1,36 @@
+// run-pass
+#![allow(dead_code)]
+#![allow(non_snake_case)]
+
+use std::ops::Add;
+
+trait Positioned<S> {
+  fn SetX(&mut self, _: S);
+  fn X(&self) -> S;
+}
+
+trait Movable<S: Add<Output=S>>: Positioned<S> {
+  fn translate(&mut self, dx: S) {
+    let x = self.X() + dx;
+    self.SetX(x);
+  }
+}
+
+struct Point { x: isize, y: isize }
+
+impl Positioned<isize> for Point {
+    fn SetX(&mut self, x: isize) {
+        self.x = x;
+    }
+    fn X(&self) -> isize {
+        self.x
+    }
+}
+
+impl Movable<isize> for Point {}
+
+pub fn main() {
+    let mut p = Point{ x: 1, y: 2};
+    p.translate(3);
+    assert_eq!(p.X(), 4);
+}