Auto merge of #50016 - tmandry:cleanup-binder, r=nikomatsakis

Make Binder's field private and clean up its usage

AKA "tour de rustc"

Closes #49814.

src/librustc/ich/impls_ty.rs

@@ -262,8 +262,7 @@ impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>> for ty::Binder<T>
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
-        let ty::Binder(ref inner) = *self;
-        inner.hash_stable(hcx, hasher);
+        self.skip_binder().hash_stable(hcx, hasher);
     }
 }
 

src/librustc/infer/canonical.rs

@@ -388,14 +388,16 @@ impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
                     Obligation::new(
                         cause.clone(),
                         param_env,
-                        ty::Predicate::RegionOutlives(ty::Binder(ty::OutlivesPredicate(r1, r2))),
+                        ty::Predicate::RegionOutlives(
+                            ty::Binder::dummy(ty::OutlivesPredicate(r1, r2))),
                     ),
 
                 UnpackedKind::Type(t1) =>
                     Obligation::new(
                         cause.clone(),
                         param_env,
-                        ty::Predicate::TypeOutlives(ty::Binder(ty::OutlivesPredicate(t1, r2))),
+                        ty::Predicate::TypeOutlives(
+                            ty::Binder::dummy(ty::OutlivesPredicate(t1, r2))),
                     ),
             }
         })) as Box<dyn Iterator<Item = _>>

src/librustc/infer/combine.rs

@@ -302,7 +302,7 @@ struct Generalizer<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
 
 /// Result from a generalization operation. This includes
 /// not only the generalized type, but also a bool flag
-/// indicating whether further WF checks are needed.q
+/// indicating whether further WF checks are needed.
 struct Generalization<'tcx> {
     ty: Ty<'tcx>,
 
@@ -351,7 +351,7 @@ impl<'cx, 'gcx, 'tcx> TypeRelation<'cx, 'gcx, 'tcx> for Generalizer<'cx, 'gcx, '
                   -> RelateResult<'tcx, ty::Binder<T>>
         where T: Relate<'tcx>
     {
-        Ok(ty::Binder(self.relate(a.skip_binder(), b.skip_binder())?))
+        Ok(ty::Binder::bind(self.relate(a.skip_binder(), b.skip_binder())?))
     }
 
     fn relate_item_substs(&mut self,

src/librustc/infer/error_reporting/mod.rs

@@ -916,7 +916,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                         };
 
                         if let (Some(def_id), Some(ret_ty)) = (def_id, ret_ty) {
-                            if exp_is_struct && exp_found.expected == ret_ty.0 {
+                            if exp_is_struct && &exp_found.expected == ret_ty.skip_binder() {
                                 let message = format!(
                                     "did you mean `{}(/* fields */)`?",
                                     self.tcx.item_path_str(def_id)

src/librustc/infer/higher_ranked/mod.rs

@@ -80,7 +80,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
 
             debug!("higher_ranked_sub: OK result={:?}", result);
 
-            Ok(ty::Binder(result))
+            Ok(ty::Binder::bind(result))
         });
     }
 
@@ -239,7 +239,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
                    b,
                    result1);
 
-            Ok(ty::Binder(result1))
+            Ok(ty::Binder::bind(result1))
         });
 
         fn generalize_region<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
@@ -335,7 +335,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
                    b,
                    result1);
 
-            Ok(ty::Binder(result1))
+            Ok(ty::Binder::bind(result1))
         });
 
         fn generalize_region<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,

src/librustc/infer/sub.rs

@@ -98,7 +98,7 @@ impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx>
                         self.fields.trace.cause.clone(),
                         self.fields.param_env,
                         ty::Predicate::Subtype(
-                            ty::Binder(ty::SubtypePredicate {
+                            ty::Binder::dummy(ty::SubtypePredicate {
                                 a_is_expected: self.a_is_expected,
                                 a,
                                 b,

src/librustc/traits/error_reporting.rs

@@ -537,7 +537,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                     &data.parent_trait_ref);
                 match self.get_parent_trait_ref(&data.parent_code) {
                     Some(t) => Some(t),
-                    None => Some(format!("{}", parent_trait_ref.0.self_ty())),
+                    None => Some(format!("{}", parent_trait_ref.skip_binder().self_ty())),
                 }
             }
             _ => None,
@@ -862,7 +862,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                                 obligation: &PredicateObligation<'tcx>,
                                 err: &mut DiagnosticBuilder<'tcx>,
                                 trait_ref: &ty::Binder<ty::TraitRef<'tcx>>) {
-        let ty::Binder(trait_ref) = trait_ref;
+        let trait_ref = trait_ref.skip_binder();
         let span = obligation.cause.span;
 
         if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
@@ -1102,7 +1102,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                     ::syntax::abi::Abi::Rust
                 )
             };
-            format!("{}", ty::Binder(sig))
+            format!("{}", ty::Binder::bind(sig))
         }
 
         let argument_is_closure = expected_ref.skip_binder().substs.type_at(0).is_closure();
@@ -1436,7 +1436,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             }
             ObligationCauseCode::BuiltinDerivedObligation(ref data) => {
                 let parent_trait_ref = self.resolve_type_vars_if_possible(&data.parent_trait_ref);
-                let ty = parent_trait_ref.0.self_ty();
+                let ty = parent_trait_ref.skip_binder().self_ty();
                 err.note(&format!("required because it appears within the type `{}`", ty));
                 obligated_types.push(ty);
 
@@ -1453,7 +1453,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 err.note(
                     &format!("required because of the requirements on the impl of `{}` for `{}`",
                              parent_trait_ref,
-                             parent_trait_ref.0.self_ty()));
+                             parent_trait_ref.skip_binder().self_ty()));
                 let parent_predicate = parent_trait_ref.to_predicate();
                 self.note_obligation_cause_code(err,
                                             &parent_predicate,
@@ -1484,7 +1484,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         if let ObligationCauseCode::BuiltinDerivedObligation(ref data) = cause_code {
             let parent_trait_ref = self.resolve_type_vars_if_possible(&data.parent_trait_ref);
             for obligated_type in obligated_types {
-                if obligated_type == &parent_trait_ref.0.self_ty() {
+                if obligated_type == &parent_trait_ref.skip_binder().self_ty() {
                     return true;
                 }
             }

src/librustc/traits/mod.rs

@@ -855,16 +855,19 @@ fn vtable_methods<'a, 'tcx>(
 
                 // the method may have some early-bound lifetimes, add
                 // regions for those
-                let substs = Substs::for_item(tcx, def_id,
-                                              |_, _| tcx.types.re_erased,
-                                              |def, _| trait_ref.substs().type_for_def(def));
+                let substs = trait_ref.map_bound(|trait_ref| {
+                    Substs::for_item(
+                        tcx, def_id,
+                        |_, _| tcx.types.re_erased,
+                        |def, _| trait_ref.substs.type_for_def(def))
+                });
 
                 // the trait type may have higher-ranked lifetimes in it;
                 // so erase them if they appear, so that we get the type
                 // at some particular call site
                 let substs = tcx.normalize_erasing_late_bound_regions(
                     ty::ParamEnv::reveal_all(),
-                    &ty::Binder(substs),
+                    &substs
                 );
 
                 // It's possible that the method relies on where clauses that
@@ -997,7 +1000,7 @@ impl<'tcx> FulfillmentError<'tcx> {
 
 impl<'tcx> TraitObligation<'tcx> {
     fn self_ty(&self) -> ty::Binder<Ty<'tcx>> {
-        ty::Binder(self.predicate.skip_binder().self_ty())
+        self.predicate.map_bound(|p| p.self_ty())
     }
 }
 

src/librustc/traits/object_safety.rs

@@ -149,7 +149,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         trait_def_id: DefId,
         supertraits_only: bool) -> bool
     {
-        let trait_ref = ty::Binder(ty::TraitRef {
+        let trait_ref = ty::Binder::dummy(ty::TraitRef {
             def_id: trait_def_id,
             substs: Substs::identity_for_item(self, trait_def_id)
         });
@@ -199,7 +199,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             .any(|predicate| {
                 match predicate {
                     ty::Predicate::Trait(ref trait_pred) if trait_pred.def_id() == sized_def_id => {
-                        trait_pred.0.self_ty().is_self()
+                        trait_pred.skip_binder().self_ty().is_self()
                     }
                     ty::Predicate::Projection(..) |
                     ty::Predicate::Trait(..) |
@@ -352,7 +352,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
                     // Compute supertraits of current trait lazily.
                     if supertraits.is_none() {
-                        let trait_ref = ty::Binder(ty::TraitRef {
+                        let trait_ref = ty::Binder::bind(ty::TraitRef {
                             def_id: trait_def_id,
                             substs: Substs::identity_for_item(self, trait_def_id)
                         });
@@ -367,7 +367,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                     // direct equality here because all of these types
                     // are part of the formal parameter listing, and
                     // hence there should be no inference variables.
-                    let projection_trait_ref = ty::Binder(data.trait_ref(self));
+                    let projection_trait_ref = ty::Binder::bind(data.trait_ref(self));
                     let is_supertrait_of_current_trait =
                         supertraits.as_ref().unwrap().contains(&projection_trait_ref);
 

src/librustc/traits/project.rs

@@ -478,7 +478,7 @@ pub fn normalize_projection_type<'a, 'b, 'gcx, 'tcx>(
             let def_id = projection_ty.item_def_id;
             let ty_var = selcx.infcx().next_ty_var(
                 TypeVariableOrigin::NormalizeProjectionType(tcx.def_span(def_id)));
-            let projection = ty::Binder(ty::ProjectionPredicate {
+            let projection = ty::Binder::dummy(ty::ProjectionPredicate {
                 projection_ty,
                 ty: ty_var
             });
@@ -982,8 +982,7 @@ fn assemble_candidates_from_predicates<'cx, 'gcx, 'tcx, I>(
                predicate);
         match predicate {
             ty::Predicate::Projection(data) => {
-                let same_def_id =
-                    data.0.projection_ty.item_def_id == obligation.predicate.item_def_id;
+                let same_def_id = data.projection_def_id() == obligation.predicate.item_def_id;
 
                 let is_match = same_def_id && infcx.probe(|_| {
                     let data_poly_trait_ref =
@@ -1241,7 +1240,7 @@ fn confirm_object_candidate<'cx, 'gcx, 'tcx>(
         // item with the correct name
         let env_predicates = env_predicates.filter_map(|p| match p {
             ty::Predicate::Projection(data) =>
-                if data.0.projection_ty.item_def_id == obligation.predicate.item_def_id {
+                if data.projection_def_id() == obligation.predicate.item_def_id {
                     Some(data)
                 } else {
                     None
@@ -1302,28 +1301,28 @@ fn confirm_generator_candidate<'cx, 'gcx, 'tcx>(
 
     let gen_def_id = tcx.lang_items().gen_trait().unwrap();
 
-    // Note: we unwrap the binder here but re-create it below (1)
-    let ty::Binder((trait_ref, yield_ty, return_ty)) =
+    let predicate =
         tcx.generator_trait_ref_and_outputs(gen_def_id,
                                             obligation.predicate.self_ty(),
-                                            gen_sig);
-
-    let name = tcx.associated_item(obligation.predicate.item_def_id).name;
-    let ty = if name == Symbol::intern("Return") {
-        return_ty
-    } else if name == Symbol::intern("Yield") {
-        yield_ty
-    } else {
-        bug!()
-    };
+                                            gen_sig)
+        .map_bound(|(trait_ref, yield_ty, return_ty)| {
+            let name = tcx.associated_item(obligation.predicate.item_def_id).name;
+            let ty = if name == Symbol::intern("Return") {
+                return_ty
+            } else if name == Symbol::intern("Yield") {
+                yield_ty
+            } else {
+                bug!()
+            };
 
-    let predicate = ty::Binder(ty::ProjectionPredicate { // (1) recreate binder here
-        projection_ty: ty::ProjectionTy {
-            substs: trait_ref.substs,
-            item_def_id: obligation.predicate.item_def_id,
-        },
-        ty: ty
-    });
+            ty::ProjectionPredicate {
+                projection_ty: ty::ProjectionTy {
+                    substs: trait_ref.substs,
+                    item_def_id: obligation.predicate.item_def_id,
+                },
+                ty: ty
+            }
+        });
 
     confirm_param_env_candidate(selcx, obligation, predicate)
         .with_addl_obligations(vtable.nested)
@@ -1400,21 +1399,21 @@ fn confirm_callable_candidate<'cx, 'gcx, 'tcx>(
     // the `Output` associated type is declared on `FnOnce`
     let fn_once_def_id = tcx.lang_items().fn_once_trait().unwrap();
 
-    // Note: we unwrap the binder here but re-create it below (1)
-    let ty::Binder((trait_ref, ret_type)) =
+    let predicate =
         tcx.closure_trait_ref_and_return_type(fn_once_def_id,
                                               obligation.predicate.self_ty(),
                                               fn_sig,
-                                              flag);
-
-    let predicate = ty::Binder(ty::ProjectionPredicate { // (1) recreate binder here
-        projection_ty: ty::ProjectionTy::from_ref_and_name(
-            tcx,
-            trait_ref,
-            Symbol::intern(FN_OUTPUT_NAME),
-        ),
-        ty: ret_type
-    });
+                                              flag)
+        .map_bound(|(trait_ref, ret_type)| {
+            ty::ProjectionPredicate {
+                projection_ty: ty::ProjectionTy::from_ref_and_name(
+                    tcx,
+                    trait_ref,
+                    Symbol::intern(FN_OUTPUT_NAME),
+                ),
+                ty: ret_type
+            }
+        });
 
     confirm_param_env_candidate(selcx, obligation, predicate)
 }