testsuite: Add passing test for #4107

src/test/run-pass/issue-4107.rs

@@ -0,0 +1,33 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    let id: &Mat2<float> = &Matrix::identity();
+}
+
+pub trait Index<Index,Result> { }
+pub trait Dimensional<T>: Index<uint, T> { }
+
+pub struct Mat2<T> { x: () }
+pub struct Vec2<T> { x: () }
+
+impl<T> Dimensional<Vec2<T>> for Mat2<T> { }
+impl<T> Index<uint, Vec2<T>> for Mat2<T> { }
+
+impl<T> Dimensional<T> for Vec2<T> { }
+impl<T> Index<uint, T> for Vec2<T> { }
+
+pub trait Matrix<T,V>: Dimensional<V> {
+    fn identity() -> Self;
+}
+
+impl<T> Matrix<T, Vec2<T>> for Mat2<T> {
+    fn identity() -> Mat2<T> { Mat2{ x: () } }
+}