1 files changed, 26 insertions, 0 deletions
diff --git a/tests/ui/traits/issue-4107.rs b/tests/ui/traits/issue-4107.rs
new file mode 100644
index 000000000..98433e806
--- /dev/null
+++ b/tests/ui/traits/issue-4107.rs
@@ -0,0 +1,26 @@
+// run-pass
+#![allow(dead_code)]
+
+pub fn main() {
+    let _id: &Mat2<f64> = &Matrix::identity(1.0);
+}
+
+pub trait Index<Index,Result> { fn get(&self, _: Index) -> Result { panic!() } }
+pub trait Dimensional<T>: Index<usize, T> { }
+
+pub struct Mat2<T> { x: T }
+pub struct Vec2<T> { x: T }
+
+impl<T> Dimensional<Vec2<T>> for Mat2<T> { }
+impl<T> Index<usize, Vec2<T>> for Mat2<T> { }
+
+impl<T> Dimensional<T> for Vec2<T> { }
+impl<T> Index<usize, T> for Vec2<T> { }
+
+pub trait Matrix<T,V>: Dimensional<V> {
+    fn identity(t:T) -> Self;
+}
+
+impl<T> Matrix<T, Vec2<T>> for Mat2<T> {
+    fn identity(t:T) -> Mat2<T> { Mat2{ x: t } }
+}