Use constraint span when lowering associated types

Author: estebank

src/librustc/hir/lowering.rs

@@ -72,7 +72,7 @@ use syntax::symbol::{kw, sym, Symbol};
 use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::parse::token::{self, Token};
 use syntax::visit::{self, Visitor};
-use syntax_pos::{DUMMY_SP, Span};
+use syntax_pos::Span;
 
 const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;
 
@@ -1094,15 +1094,15 @@ impl<'a> LoweringContext<'a> {
                         impl_trait_node_id,
                         DefPathData::ImplTrait,
                         ExpnId::root(),
-                        DUMMY_SP
+                        c.span,
                     );
 
                     self.with_dyn_type_scope(false, |this| {
                         let ty = this.lower_ty(
                             &Ty {
                                 id: this.sess.next_node_id(),
                                 node: TyKind::ImplTrait(impl_trait_node_id, bounds.clone()),
-                                span: DUMMY_SP,
+                                span: c.span,
                             },
                             itctx,
                         );

src/librustc/infer/opaque_types/mod.rs

@@ -127,8 +127,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     ) -> InferOk<'tcx, (T, OpaqueTypeMap<'tcx>)> {
         debug!(
             "instantiate_opaque_types(value={:?}, parent_def_id={:?}, body_id={:?}, \
-             param_env={:?})",
-            value, parent_def_id, body_id, param_env,
+             param_env={:?}, value_span={:?})",
+            value, parent_def_id, body_id, param_env, value_span,
         );
         let mut instantiator = Instantiator {
             infcx: self,
@@ -1111,6 +1111,7 @@ impl<'a, 'tcx> Instantiator<'a, 'tcx> {
             return opaque_defn.concrete_ty;
         }
         let span = tcx.def_span(def_id);
+        debug!("fold_opaque_ty {:?} {:?}", self.value_span, span);
         let ty_var = infcx
             .next_ty_var(TypeVariableOrigin { kind: TypeVariableOriginKind::TypeInference, span });
 

src/librustc/traits/fulfill.rs

@@ -248,10 +248,10 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
     /// This is always inlined, despite its size, because it has a single
     /// callsite and it is called *very* frequently.
     #[inline(always)]
-    fn process_obligation(&mut self,
-                          pending_obligation: &mut Self::Obligation)
-                          -> ProcessResult<Self::Obligation, Self::Error>
-    {
+    fn process_obligation(
+        &mut self,
+        pending_obligation: &mut Self::Obligation,
+    ) -> ProcessResult<Self::Obligation, Self::Error> {
         // if we were stalled on some unresolved variables, first check
         // whether any of them have been resolved; if not, don't bother
         // doing more work yet
@@ -277,7 +277,7 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
                 self.selcx.infcx().resolve_vars_if_possible(&obligation.predicate);
         }
 
-        debug!("process_obligation: obligation = {:?}", obligation);
+        debug!("process_obligation: obligation = {:?} cause = {:?}", obligation, obligation.cause);
 
         match obligation.predicate {
             ty::Predicate::Trait(ref data) => {
@@ -425,10 +425,13 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
             }
 
             ty::Predicate::WellFormed(ty) => {
-                match ty::wf::obligations(self.selcx.infcx(),
+                match ty::wf::obligations(
+                    self.selcx.infcx(),
                                           obligation.param_env,
                                           obligation.cause.body_id,
-                                          ty, obligation.cause.span) {
+                    ty,
+                    obligation.cause.span,
+                ) {
                     None => {
                         pending_obligation.stalled_on = vec![ty];
                         ProcessResult::Unchanged

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

@@ -0,0 +1,22 @@
+#![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-item/associated-item-type-issue-63594.stderr

@@ -0,0 +1,11 @@
+error[E0277]: the trait bound `std::string::String: std::marker::Copy` is not satisfied
+  --> $DIR/associated-item-type-issue-63594.rs:16:28
+   |
+LL |     type Out = Box<dyn Bar<Assoc: Copy>>;
+   |                            ^^^^^^^^^^^ the trait `std::marker::Copy` is not implemented for `std::string::String`
+   |
+   = note: the return type of a function must have a statically known size
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.