1 files changed, 21 insertions, 0 deletions
diff --git a/src/test/ui/auto-traits/typeck-default-trait-impl-precedence.rs b/src/test/ui/auto-traits/typeck-default-trait-impl-precedence.rs
new file mode 100644
index 000000000..2bbe82270
--- /dev/null
+++ b/src/test/ui/auto-traits/typeck-default-trait-impl-precedence.rs
@@ -0,0 +1,21 @@
+// Test that declaring that `&T` is `Defaulted` if `T:Signed` implies
+// that other `&T` is NOT `Defaulted` if `T:Signed` does not hold. In
+// other words, the auto impl only applies if there are no existing
+// impls whose types unify.
+
+#![feature(auto_traits)]
+#![feature(negative_impls)]
+
+auto trait Defaulted { }
+impl<'a,T:Signed> Defaulted for &'a T { }
+impl<'a,T:Signed> Defaulted for &'a mut T { }
+fn is_defaulted<T:Defaulted>() { }
+
+trait Signed { }
+impl Signed for i32 { }
+
+fn main() {
+    is_defaulted::<&'static i32>();
+    is_defaulted::<&'static u32>();
+    //~^ ERROR `u32: Signed` is not satisfied
+}