1 files changed, 70 insertions, 0 deletions
diff --git a/src/test/ui/traits/issue-33140-hack-boundaries.rs b/src/test/ui/traits/issue-33140-hack-boundaries.rs
new file mode 100644
index 000000000..d091162fc
--- /dev/null
+++ b/src/test/ui/traits/issue-33140-hack-boundaries.rs
@@ -0,0 +1,70 @@
+#![feature(negative_impls)]
+#![allow(order_dependent_trait_objects)]
+
+// Check that the issue #33140 hack does not allow unintended things.
+
+// OK
+trait Trait0 {}
+
+impl Trait0 for dyn Send {}
+impl Trait0 for dyn Send {}
+
+// Problem 1: associated types
+trait Trait1 {
+    fn my_fn(&self) {}
+}
+
+impl Trait1 for dyn Send {}
+impl Trait1 for dyn Send {}
+//~^ ERROR E0119
+
+// Problem 2: negative impl
+trait Trait2 {}
+
+impl Trait2 for dyn Send {}
+impl !Trait2 for dyn Send {}
+//~^ ERROR E0751
+
+// Problem 3: type parameter
+trait Trait3<T: ?Sized> {}
+
+impl Trait3<dyn Sync> for dyn Send {}
+impl Trait3<dyn Sync> for dyn Send {}
+//~^ ERROR E0119
+
+// Problem 4a: not a trait object - generic
+trait Trait4a {}
+
+impl<T: ?Sized> Trait4a for T {}
+impl Trait4a for dyn Send {}
+//~^ ERROR E0119
+
+// Problem 4b: not a trait object - misc
+trait Trait4b {}
+
+impl Trait4b for () {}
+impl Trait4b for () {}
+//~^ ERROR E0119
+
+// Problem 4c: not a principal-less trait object
+trait Trait4c {}
+
+impl Trait4c for dyn Trait1 + Send {}
+impl Trait4c for dyn Trait1 + Send {}
+//~^ ERROR E0119
+
+// Problem 4d: lifetimes
+trait Trait4d {}
+
+impl<'a> Trait4d for dyn Send + 'a {}
+impl<'a> Trait4d for dyn Send + 'a {}
+//~^ ERROR E0119
+
+// Problem 5: where-clauses
+trait Trait5 {}
+
+impl Trait5 for dyn Send {}
+impl Trait5 for dyn Send where u32: Copy {}
+//~^ ERROR E0119
+
+fn main() {}