review comments

src/librustc/hir/lowering.rs

@@ -1033,13 +1033,14 @@ impl<'a> LoweringContext<'a> {
     /// ```
     ///
     /// returns a `hir::TypeBinding` representing `Item`.
-    fn lower_assoc_ty_constraint(&mut self,
-                                 c: &AssocTyConstraint,
-                                 itctx: ImplTraitContext<'_>)
-                                 -> hir::TypeBinding {
-        debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", c, itctx);
+    fn lower_assoc_ty_constraint(
+        &mut self,
+        constraint: &AssocTyConstraint,
+        itctx: ImplTraitContext<'_>,
+    ) -> hir::TypeBinding {
+        debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", constraint, itctx);
 
-        let kind = match c.kind {
+        let kind = match constraint.kind {
             AssocTyConstraintKind::Equality { ref ty } => hir::TypeBindingKind::Equality {
                 ty: self.lower_ty(ty, itctx)
             },
@@ -1094,7 +1095,7 @@ impl<'a> LoweringContext<'a> {
                         impl_trait_node_id,
                         DefPathData::ImplTrait,
                         ExpnId::root(),
-                        c.span,
+                        constraint.span,
                     );
 
                     self.with_dyn_type_scope(false, |this| {
@@ -1102,7 +1103,7 @@ impl<'a> LoweringContext<'a> {
                             &Ty {
                                 id: this.sess.next_node_id(),
                                 node: TyKind::ImplTrait(impl_trait_node_id, bounds.clone()),
-                                span: c.span,
+                                span: constraint.span,
                             },
                             itctx,
                         );
@@ -1124,10 +1125,10 @@ impl<'a> LoweringContext<'a> {
         };
 
         hir::TypeBinding {
-            hir_id: self.lower_node_id(c.id),
-            ident: c.ident,
+            hir_id: self.lower_node_id(constraint.id),
+            ident: constraint.ident,
             kind,
-            span: c.span,
+            span: constraint.span,
         }
     }
 

src/librustc/traits/fulfill.rs

@@ -427,8 +427,8 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
             ty::Predicate::WellFormed(ty) => {
                 match ty::wf::obligations(
                     self.selcx.infcx(),
-                                          obligation.param_env,
-                                          obligation.cause.body_id,
+                    obligation.param_env,
+                    obligation.cause.body_id,
                     ty,
                     obligation.cause.span,
                 ) {

src/test/ui/associated-item/associated-item-type-issue-63594.rs

@@ -1,22 +0,0 @@
-#![feature(associated_type_bounds)]
-
-fn main() {}
-
-trait Bar { type Assoc; }
-
-trait Thing {
-    type Out;
-    fn func() -> Self::Out;
-}
-
-struct AssocNoCopy;
-impl Bar for AssocNoCopy { type Assoc = String; }
-
-impl Thing for AssocNoCopy {
-    type Out = Box<dyn Bar<Assoc: Copy>>;
-    //~^ ERROR the trait bound `std::string::String: std::marker::Copy` is not satisfied
-
-    fn func() -> Self::Out {
-        Box::new(AssocNoCopy)
-    }
-}

src/test/ui/associated-type-bounds/assoc-type-eq-with-dyn-atb-fail.rs

@@ -0,0 +1,32 @@
+// This test documents that `type Out = Box<dyn Bar<Assoc: Copy>>;`
+// is allowed and will correctly reject an opaque `type Out` which
+// does not satisfy the bound `<TheType as Bar>::Assoc: Copy`.
+//
+// FIXME(rust-lang/lang): I think this behavior is logical if we want to allow
+// `dyn Trait<Assoc: Bound>` but we should decide if we want that. // Centril
+//
+// Additionally, as reported in https://github.com/rust-lang/rust/issues/63594,
+// we check that the spans for the error message are sane here.
+
+#![feature(associated_type_bounds)]
+
+fn main() {}
+
+trait Bar { type Assoc; }
+
+trait Thing {
+    type Out;
+    fn func() -> Self::Out;
+}
+
+struct AssocNoCopy;
+impl Bar for AssocNoCopy { type Assoc = String; }
+
+impl Thing for AssocNoCopy {
+    type Out = Box<dyn Bar<Assoc: Copy>>;
+    //~^ ERROR the trait bound `std::string::String: std::marker::Copy` is not satisfied
+
+    fn func() -> Self::Out {
+        Box::new(AssocNoCopy)
+    }
+}

src/test/ui/associated-type-bounds/assoc-type-eq-with-dyn-atb-fail.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `std::string::String: std::marker::Copy` is not satisfied
-  --> $DIR/associated-item-type-issue-63594.rs:16:28
+  --> $DIR/assoc-type-eq-with-dyn-atb-fail.rs:26:28
    |
 LL |     type Out = Box<dyn Bar<Assoc: Copy>>;
    |                            ^^^^^^^^^^^ the trait `std::marker::Copy` is not implemented for `std::string::String`