rollup merge of #20594: nikomatsakis/orphan-ordered

[rust.git] / src / librustc_typeck / coherence / orphan.rs

diff --git a/src/librustc_typeck/coherence/orphan.rs b/src/librustc_typeck/coherence/orphan.rs
index d90bfe04ea1e78ceaa700c888b7a604a2e21f71e..77d71e740d681f8c626bc173e1139b8e87cca468 100644 (file)
--- a/src/librustc_typeck/coherence/orphan.rs
+++ b/src/librustc_typeck/coherence/orphan.rs
@@ -72,20 +72,30 @@ fn visit_item(&mut self, item: &'v ast::Item) {
             ast::ItemImpl(_, _, _, Some(_), _, _) => {
                 // "Trait" impl
                 debug!("coherence2::orphan check: trait impl {}", item.repr(self.tcx));
+                let trait_def_id = ty::impl_trait_ref(self.tcx, def_id).unwrap().def_id;
                 match traits::orphan_check(self.tcx, def_id) {
                     Ok(()) => { }
                     Err(traits::OrphanCheckErr::NoLocalInputType) => {
-                        span_err!(self.tcx.sess, item.span, E0117,
-                                  "cannot provide an extension implementation \
-                                   where both trait and type are not defined in this crate");
+                        if !ty::has_attr(self.tcx, trait_def_id, "old_orphan_check") {
+                            let self_ty = ty::lookup_item_type(self.tcx, def_id).ty;
+                            span_err!(
+                                self.tcx.sess, item.span, E0117,
+                                "the type `{}` does not reference any \
+                                 types defined in this crate; \
+                                 only traits defined in the current crate can be \
+                                 implemented for arbitrary types",
+                                self_ty.user_string(self.tcx));
+                        }
                     }
-                    Err(traits::OrphanCheckErr::UncoveredTypeParameter(param_ty)) => {
-                        if !self.tcx.sess.features.borrow().old_orphan_check {
+                    Err(traits::OrphanCheckErr::UncoveredTy(param_ty)) => {
+                        if !ty::has_attr(self.tcx, trait_def_id, "old_orphan_check") {
                             self.tcx.sess.span_err(
                                 item.span,
-                                format!("type parameter `{}` must also appear as a type parameter \
-                                         of some type defined within this crate",
-                                        param_ty.user_string(self.tcx)).as_slice());
+                                format!(
+                                    "type parameter `{}` is not constrained by any local type; \
+                                     only traits defined in the current crate can be implemented \
+                                     for a type parameter",
+                                    param_ty.user_string(self.tcx)).as_slice());
                             self.tcx.sess.span_note(
                                 item.span,
                                 format!("for a limited time, you can add \