1 files changed, 54 insertions, 0 deletions
diff --git a/tests/ui/specialization/non-defaulted-item-fail.rs b/tests/ui/specialization/non-defaulted-item-fail.rs
new file mode 100644
index 00000000000..b7d6ac829dd
--- /dev/null
+++ b/tests/ui/specialization/non-defaulted-item-fail.rs
@@ -0,0 +1,54 @@
+#![feature(specialization, associated_type_defaults)]
+//~^ WARN the feature `specialization` is incomplete
+
+// Test that attempting to override a non-default method or one not in the
+// parent impl causes an error.
+
+trait Foo {
+    type Ty = ();
+    const CONST: u8 = 123;
+    fn foo(&self) -> bool { true }
+}
+
+// Specialization tree for Foo:
+//
+//       Box<T>              Vec<T>
+//        / \                 / \
+// Box<i32>  Box<i64>   Vec<()>  Vec<bool>
+
+impl<T> Foo for Box<T> {
+    type Ty = bool;
+    const CONST: u8 = 0;
+    fn foo(&self) -> bool { false }
+}
+
+// Allowed
+impl Foo for Box<i32> {}
+
+// Can't override a non-`default` fn
+impl Foo for Box<i64> {
+    type Ty = Vec<()>;
+//~^ error: `Ty` specializes an item from a parent `impl`, but that item is not marked `default`
+    const CONST: u8 = 42;
+//~^ error: `CONST` specializes an item from a parent `impl`, but that item is not marked `default`
+    fn foo(&self) -> bool { true }
+//~^ error: `foo` specializes an item from a parent `impl`, but that item is not marked `default`
+}
+
+
+// Doesn't mention the item = provided body/value is used and the method is final.
+impl<T> Foo for Vec<T> {}
+
+// Allowed
+impl Foo for Vec<()> {}
+
+impl Foo for Vec<bool> {
+    type Ty = Vec<()>;
+//~^ error: `Ty` specializes an item from a parent `impl`, but that item is not marked `default`
+    const CONST: u8 = 42;
+//~^ error: `CONST` specializes an item from a parent `impl`, but that item is not marked `default`
+    fn foo(&self) -> bool { true }
+//~^ error: `foo` specializes an item from a parent `impl`, but that item is not marked `default`
+}
+
+fn main() {}