expand WF obligations when checking method calls

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -356,14 +356,14 @@ fn compare_method_predicate_entailment<'tcx>(
     }
 
     if !(impl_sig, trait_sig).references_error() {
-        ocx.register_obligation(traits::Obligation::new(
-            infcx.tcx,
-            cause,
-            param_env,
-            ty::ClauseKind::WellFormed(
-                Ty::new_fn_ptr(tcx, ty::Binder::dummy(unnormalized_impl_sig)).into(),
-            ),
-        ));
+        for ty in unnormalized_impl_sig.inputs_and_output {
+            ocx.register_obligation(traits::Obligation::new(
+                infcx.tcx,
+                cause.clone(),
+                param_env,
+                ty::ClauseKind::WellFormed(ty.into()),
+            ));
+        }
     }
 
     // Check that all obligations are satisfied by the implementation's

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -142,7 +142,6 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
 
         let (method_sig, method_predicates) =
             self.normalize(self.span, (method_sig, method_predicates));
-        let method_sig = ty::Binder::dummy(method_sig);
 
         // Make sure nobody calls `drop()` explicitly.
         self.check_for_illegal_method_calls(pick);
@@ -154,20 +153,11 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
         // We won't add these if we encountered an illegal sized bound, so that we can use
         // a custom error in that case.
         if illegal_sized_bound.is_none() {
-            self.add_obligations(
-                Ty::new_fn_ptr(self.tcx, method_sig),
-                all_args,
-                method_predicates,
-                pick.item.def_id,
-            );
+            self.add_obligations(method_sig, all_args, method_predicates, pick.item.def_id);
         }
 
         // Create the final `MethodCallee`.
-        let callee = MethodCallee {
-            def_id: pick.item.def_id,
-            args: all_args,
-            sig: method_sig.skip_binder(),
-        };
+        let callee = MethodCallee { def_id: pick.item.def_id, args: all_args, sig: method_sig };
         ConfirmResult { callee, illegal_sized_bound }
     }
 
@@ -601,14 +591,14 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
 
     fn add_obligations(
         &mut self,
-        fty: Ty<'tcx>,
+        sig: ty::FnSig<'tcx>,
         all_args: GenericArgsRef<'tcx>,
         method_predicates: ty::InstantiatedPredicates<'tcx>,
         def_id: DefId,
     ) {
         debug!(
-            "add_obligations: fty={:?} all_args={:?} method_predicates={:?} def_id={:?}",
-            fty, all_args, method_predicates, def_id
+            "add_obligations: sig={:?} all_args={:?} method_predicates={:?} def_id={:?}",
+            sig, all_args, method_predicates, def_id
         );
 
         // FIXME: could replace with the following, but we already calculated `method_predicates`,
@@ -637,7 +627,13 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
         // the function type must also be well-formed (this is not
         // implied by the args being well-formed because of inherent
         // impls and late-bound regions - see issue #28609).
-        self.register_wf_obligation(fty.into(), self.span, ObligationCauseCode::WellFormed(None));
+        for ty in sig.inputs_and_output {
+            self.register_wf_obligation(
+                ty.into(),
+                self.span,
+                ObligationCauseCode::WellFormed(None),
+            );
+        }
     }
 
     ///////////////////////////////////////////////////////////////////////////

compiler/rustc_hir_typeck/src/method/mod.rs

@@ -428,19 +428,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ));
 
         // Also add an obligation for the method type being well-formed.
-        let method_ty = Ty::new_fn_ptr(tcx, ty::Binder::dummy(fn_sig));
         debug!(
-            "lookup_method_in_trait: matched method method_ty={:?} obligation={:?}",
-            method_ty, obligation
+            "lookup_method_in_trait: matched method fn_sig={:?} obligation={:?}",
+            fn_sig, obligation
         );
-        obligations.push(traits::Obligation::new(
-            tcx,
-            obligation.cause,
-            self.param_env,
-            ty::Binder::dummy(ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(
-                method_ty.into(),
-            ))),
-        ));
+        for ty in fn_sig.inputs_and_output {
+            obligations.push(traits::Obligation::new(
+                tcx,
+                obligation.cause.clone(),
+                self.param_env,
+                ty::Binder::dummy(ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(ty.into()))),
+            ));
+        }
 
         let callee = MethodCallee { def_id, args, sig: fn_sig };
         debug!("callee = {:?}", callee);