Add derive for `core::marker::ConstParamTy`

This makes it easier to implement it for a type, just like `Copy`.

1 files changed, 33 insertions, 0 deletions

diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.rs
new file mode 100644
index 00000000000..d70377a20c1
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.rs
@@ -0,0 +1,33 @@
+#![allow(incomplete_features)]
+#![feature(adt_const_params, structural_match)]
+
+union Union {
+    a: u8,
+}
+
+impl PartialEq for Union {
+    fn eq(&self, other: &Union) -> bool {
+        true
+    }
+}
+impl Eq for Union {}
+impl std::marker::StructuralEq for Union {}
+
+impl std::marker::ConstParamTy for Union {}
+
+#[derive(std::marker::ConstParamTy)]
+//~^ ERROR this trait cannot be derived for unions
+union UnionDerive {
+    a: u8,
+}
+
+impl PartialEq for UnionDerive {
+    fn eq(&self, other: &UnionDerive) -> bool {
+        true
+    }
+}
+impl Eq for UnionDerive {}
+impl std::marker::StructuralEq for UnionDerive {}
+
+
+fn main() {}