Assert that various types have the right amount of generic args and fix the sites that used the wrong amount

14 files changed, 74 insertions, 85 deletions

diff --git a/compiler/rustc_trait_selection/src/autoderef.rs b/compiler/rustc_trait_selection/src/autoderef.rs
index b7240a82897..adef967b0a1 100644
--- a/compiler/rustc_trait_selection/src/autoderef.rs
+++ b/compiler/rustc_trait_selection/src/autoderef.rs
@@ -4,7 +4,7 @@ use crate::traits::{self, TraitEngine, TraitEngineExt};
 use rustc_hir as hir;
 use rustc_infer::infer::InferCtxt;
 use rustc_middle::ty::TypeVisitable;
-use rustc_middle::ty::{self, TraitRef, Ty, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_session::Limit;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::Span;
@@ -122,10 +122,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
         let tcx = self.infcx.tcx;
 
         // <ty as Deref>
-        let trait_ref = TraitRef {
-            def_id: tcx.lang_items().deref_trait()?,
-            substs: tcx.mk_substs_trait(ty, &[]),
-        };
+        let trait_ref = tcx.mk_trait_ref(tcx.lang_items().deref_trait()?, ty, &[]);
 
         let cause = traits::ObligationCause::misc(self.span, self.body_id);
 
diff --git a/compiler/rustc_trait_selection/src/infer.rs b/compiler/rustc_trait_selection/src/infer.rs
index 73e220dc7af..5be49996a0b 100644
--- a/compiler/rustc_trait_selection/src/infer.rs
+++ b/compiler/rustc_trait_selection/src/infer.rs
@@ -117,10 +117,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         params: SubstsRef<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> traits::EvaluationResult {
-        let trait_ref = ty::TraitRef {
-            def_id: trait_def_id,
-            substs: self.tcx.mk_substs_trait(self_ty, params),
-        };
+        let trait_ref = self.tcx.mk_trait_ref(trait_def_id, self_ty, params);
 
         debug_assert_eq!(
             self.tcx.generics_of(trait_def_id).count() - 1,
diff --git a/compiler/rustc_trait_selection/src/traits/auto_trait.rs b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
index 5869bc76b59..3dab34747f7 100644
--- a/compiler/rustc_trait_selection/src/traits/auto_trait.rs
+++ b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
@@ -86,7 +86,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
     ) -> AutoTraitResult<A> {
         let tcx = self.tcx;
 
-        let trait_ref = ty::TraitRef { def_id: trait_did, substs: tcx.mk_substs_trait(ty, &[]) };
+        let trait_ref = tcx.mk_trait_ref(trait_did, ty, &[]);
 
         let trait_pred = ty::Binder::dummy(trait_ref);
 
@@ -260,10 +260,8 @@ impl<'tcx> AutoTraitFinder<'tcx> {
         let mut already_visited = FxHashSet::default();
         let mut predicates = VecDeque::new();
         predicates.push_back(ty::Binder::dummy(ty::TraitPredicate {
-            trait_ref: ty::TraitRef {
-                def_id: trait_did,
-                substs: infcx.tcx.mk_substs_trait(ty, &[]),
-            },
+            trait_ref: infcx.tcx.mk_trait_ref(trait_did, ty, &[]),
+
             constness: ty::BoundConstness::NotConst,
             // Auto traits are positive
             polarity: ty::ImplPolarity::Positive,
diff --git a/compiler/rustc_trait_selection/src/traits/engine.rs b/compiler/rustc_trait_selection/src/traits/engine.rs
index f8346e515d7..97f4f7d795d 100644
--- a/compiler/rustc_trait_selection/src/traits/engine.rs
+++ b/compiler/rustc_trait_selection/src/traits/engine.rs
@@ -93,7 +93,7 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
         def_id: DefId,
     ) {
         let tcx = self.infcx.tcx;
-        let trait_ref = ty::TraitRef { def_id, substs: tcx.mk_substs_trait(ty, &[]) };
+        let trait_ref = tcx.mk_trait_ref(def_id, ty, &[]);
         self.register_obligation(Obligation {
             cause,
             recursion_depth: 0,
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index c3547f64b5c..cf9ba1d8421 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -347,16 +347,13 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
                     span: DUMMY_SP,
                     kind: TypeVariableOriginKind::MiscVariable,
                 });
-                let substs = self.tcx.mk_substs_trait(ty.skip_binder(), &[var.into()]);
+                let trait_ref =
+                    self.tcx.mk_trait_ref(trait_def_id, ty.skip_binder(), &[var.into()]);
                 let obligation = Obligation::new(
                     self.tcx,
                     ObligationCause::dummy(),
                     param_env,
-                    ty.rebind(ty::TraitPredicate {
-                        trait_ref: ty::TraitRef::new(trait_def_id, substs),
-                        constness,
-                        polarity,
-                    }),
+                    ty.rebind(ty::TraitPredicate { trait_ref, constness, polarity }),
                 );
                 let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new_in_snapshot(self.tcx);
                 fulfill_cx.register_predicate_obligation(self, obligation);
@@ -1002,7 +999,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                             && self.fallback_has_occurred
                         {
                             let predicate = trait_predicate.map_bound(|mut trait_pred| {
-                                trait_pred.trait_ref.substs = self.tcx.mk_substs_trait(
+                                trait_pred.trait_ref = self.tcx.mk_trait_ref(
+                                    trait_pred.trait_ref.def_id,
                                     self.tcx.mk_unit(),
                                     &trait_pred.trait_ref.substs[1..],
                                 );
@@ -2029,10 +2027,11 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         trait_ref_and_ty: ty::Binder<'tcx, (ty::TraitPredicate<'tcx>, Ty<'tcx>)>,
     ) -> PredicateObligation<'tcx> {
         let trait_pred = trait_ref_and_ty.map_bound_ref(|(tr, new_self_ty)| ty::TraitPredicate {
-            trait_ref: ty::TraitRef {
-                substs: self.tcx.mk_substs_trait(*new_self_ty, &tr.trait_ref.substs[1..]),
-                ..tr.trait_ref
-            },
+            trait_ref: self.tcx.mk_trait_ref(
+                tr.trait_ref.def_id,
+                *new_self_ty,
+                &tr.trait_ref.substs[1..],
+            ),
             ..*tr
         });
 
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 757977ac5d5..445b5696d20 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -3068,17 +3068,20 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 // Ensure all fields impl the trait.
                 adt.all_fields().all(|field| {
                     let field_ty = field.ty(self.tcx, substs);
-                    let trait_substs = match diagnostic_name {
+                    let trait_substs;
+                    let trait_substs: &[_] = match diagnostic_name {
                         sym::PartialEq | sym::PartialOrd => {
-                            self.tcx.mk_substs_trait(field_ty, &[field_ty.into()])
+                            trait_substs = [field_ty.into()];
+                            &trait_substs
                         }
-                        _ => self.tcx.mk_substs_trait(field_ty, &[]),
+                        _ => &[],
                     };
                     let trait_pred = trait_pred.map_bound_ref(|tr| ty::TraitPredicate {
-                        trait_ref: ty::TraitRef {
-                            substs: trait_substs,
-                            ..trait_pred.skip_binder().trait_ref
-                        },
+                        trait_ref: self.tcx.mk_trait_ref(
+                            trait_pred.def_id(),
+                            field_ty,
+                            trait_substs,
+                        ),
                         ..*tr
                     });
                     let field_obl = Obligation::new(
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index 4da19bb4a6a..227a7f0a112 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -143,8 +143,7 @@ pub fn type_known_to_meet_bound_modulo_regions<'tcx>(
     def_id: DefId,
     span: Span,
 ) -> bool {
-    let trait_ref =
-        ty::Binder::dummy(ty::TraitRef { def_id, substs: infcx.tcx.mk_substs_trait(ty, &[]) });
+    let trait_ref = ty::Binder::dummy(infcx.tcx.mk_trait_ref(def_id, ty, &[]));
     pred_known_to_hold_modulo_regions(infcx, param_env, trait_ref.without_const(), span)
 }
 
@@ -903,10 +902,7 @@ pub fn vtable_trait_upcasting_coercion_new_vptr_slot<'tcx>(
     // this has been typecked-before, so diagnostics is not really needed.
     let unsize_trait_did = tcx.require_lang_item(LangItem::Unsize, None);
 
-    let trait_ref = ty::TraitRef {
-        def_id: unsize_trait_did,
-        substs: tcx.mk_substs_trait(source, &[target.into()]),
-    };
+    let trait_ref = tcx.mk_trait_ref(unsize_trait_did, source, &[target.into()]);
 
     match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), ty::Binder::dummy(trait_ref))) {
         Ok(ImplSource::TraitUpcasting(implsrc_traitcasting)) => {
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index 9745e0137ee..20826f2c541 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -685,10 +685,11 @@ fn receiver_is_dispatchable<'tcx>(
         let param_env = tcx.param_env(method.def_id);
 
         // Self: Unsize<U>
-        let unsize_predicate = ty::Binder::dummy(ty::TraitRef {
-            def_id: unsize_did,
-            substs: tcx.mk_substs_trait(tcx.types.self_param, &[unsized_self_ty.into()]),
-        })
+        let unsize_predicate = ty::Binder::dummy(tcx.mk_trait_ref(
+            unsize_did,
+            tcx.types.self_param,
+            &[unsized_self_ty.into()],
+        ))
         .without_const()
         .to_predicate(tcx);
 
@@ -720,10 +721,11 @@ fn receiver_is_dispatchable<'tcx>(
 
     // Receiver: DispatchFromDyn<Receiver[Self => U]>
     let obligation = {
-        let predicate = ty::Binder::dummy(ty::TraitRef {
-            def_id: dispatch_from_dyn_did,
-            substs: tcx.mk_substs_trait(receiver_ty, &[unsized_receiver_ty.into()]),
-        })
+        let predicate = ty::Binder::dummy(tcx.mk_trait_ref(
+            dispatch_from_dyn_did,
+            receiver_ty,
+            &[unsized_receiver_ty.into()],
+        ))
         .without_const();
 
         Obligation::new(tcx, ObligationCause::dummy(), param_env, predicate)
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 528b98cf4a1..e1b30112e39 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1710,9 +1710,9 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                         if selcx.infcx().predicate_must_hold_modulo_regions(
                             &obligation.with(
                                 selcx.tcx(),
-                                ty::Binder::dummy(ty::TraitRef::new(
+                                ty::Binder::dummy(selcx.tcx().mk_trait_ref(
                                     selcx.tcx().require_lang_item(LangItem::Sized, None),
-                                    selcx.tcx().mk_substs_trait(self_ty, &[]),
+                                    self_ty, &[],
                                 ))
                                 .without_const(),
                             ),
@@ -1966,9 +1966,10 @@ fn confirm_pointee_candidate<'cx, 'tcx>(
         )
     });
     if check_is_sized {
-        let sized_predicate = ty::Binder::dummy(ty::TraitRef::new(
+        let sized_predicate = ty::Binder::dummy(tcx.mk_trait_ref(
             tcx.require_lang_item(LangItem::Sized, None),
-            tcx.mk_substs_trait(self_ty, &[]),
+            self_ty,
+            &[],
         ))
         .without_const();
         obligations.push(obligation.with(tcx, sized_predicate));
diff --git a/compiler/rustc_trait_selection/src/traits/relationships.rs b/compiler/rustc_trait_selection/src/traits/relationships.rs
index dfe19a5a86d..78f0807bd95 100644
--- a/compiler/rustc_trait_selection/src/traits/relationships.rs
+++ b/compiler/rustc_trait_selection/src/traits/relationships.rs
@@ -18,10 +18,10 @@ pub(crate) fn update<'tcx, T>(
     {
         let new_self_ty = infcx.tcx.types.unit;
 
-        let trait_ref = ty::TraitRef {
-            substs: infcx.tcx.mk_substs_trait(new_self_ty, &tpred.trait_ref.substs[1..]),
-            ..tpred.trait_ref
-        };
+        let trait_ref = infcx.tcx.mk_trait_ref(
+            tpred.trait_ref.def_id,
+            new_self_ty, &tpred.trait_ref.substs[1..],
+        );
 
         // Then construct a new obligation with Self = () added
         // to the ParamEnv, and see if it holds.
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index 8183f34bb3c..6b19b9297c5 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -714,10 +714,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
 
         // <ty as Deref>
-        let trait_ref = ty::TraitRef {
-            def_id: tcx.lang_items().deref_trait()?,
-            substs: tcx.mk_substs_trait(ty, &[]),
-        };
+        let trait_ref = tcx.mk_trait_ref(tcx.lang_items().deref_trait()?, ty, &[]);
 
         let obligation = traits::Obligation::new(
             tcx,
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index a496aed38ac..6d737b455bf 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -632,9 +632,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             output_ty,
             &mut nested,
         );
-        let tr = ty::Binder::dummy(ty::TraitRef::new(
+        let tr = ty::Binder::dummy(self.tcx().mk_trait_ref(
             self.tcx().require_lang_item(LangItem::Sized, None),
-            self.tcx().mk_substs_trait(output_ty, &[]),
+            output_ty,
+            &[],
         ));
         nested.push(Obligation::new(
             self.infcx.tcx,
@@ -996,9 +997,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 );
 
                 // We can only make objects from sized types.
-                let tr = ty::Binder::dummy(ty::TraitRef::new(
+                let tr = ty::Binder::dummy(tcx.mk_trait_ref(
                     tcx.require_lang_item(LangItem::Sized, None),
-                    tcx.mk_substs_trait(source, &[]),
+                    source,
+                    &[],
                 ));
                 nested.push(predicate_to_obligation(tr.without_const().to_predicate(tcx)));
 
@@ -1253,10 +1255,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         cause.clone(),
                         obligation.recursion_depth + 1,
                         self_ty.rebind(ty::TraitPredicate {
-                            trait_ref: ty::TraitRef {
-                                def_id: self.tcx().require_lang_item(LangItem::Destruct, None),
-                                substs: self.tcx().mk_substs_trait(nested_ty, &[]),
-                            },
+                            trait_ref: self.tcx().mk_trait_ref(
+                                self.tcx().require_lang_item(LangItem::Destruct, None),
+                                nested_ty,
+                                &[],
+                            ),
                             constness: ty::BoundConstness::ConstIfConst,
                             polarity: ty::ImplPolarity::Positive,
                         }),
@@ -1277,10 +1280,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 // or it's an ADT (and we need to check for a custom impl during selection)
                 _ => {
                     let predicate = self_ty.rebind(ty::TraitPredicate {
-                        trait_ref: ty::TraitRef {
-                            def_id: self.tcx().require_lang_item(LangItem::Destruct, None),
-                            substs: self.tcx().mk_substs_trait(nested_ty, &[]),
-                        },
+                        trait_ref: self.tcx().mk_trait_ref(
+                            self.tcx().require_lang_item(LangItem::Destruct, None),
+                            nested_ty,
+                            &[],
+                        ),
                         constness: ty::BoundConstness::ConstIfConst,
                         polarity: ty::ImplPolarity::Positive,
                     });
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index ed47d2f83df..21c79461eda 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -241,8 +241,7 @@ pub fn predicate_for_trait_def<'tcx>(
     self_ty: Ty<'tcx>,
     params: &[GenericArg<'tcx>],
 ) -> PredicateObligation<'tcx> {
-    let trait_ref =
-        ty::TraitRef { def_id: trait_def_id, substs: tcx.mk_substs_trait(self_ty, params) };
+    let trait_ref = tcx.mk_trait_ref(trait_def_id, self_ty, params);
     predicate_for_trait_ref(tcx, cause, param_env, trait_ref, recursion_depth)
 }
 
@@ -305,10 +304,7 @@ pub fn closure_trait_ref_and_return_type<'tcx>(
         TupleArgumentsFlag::Yes => tcx.intern_tup(sig.skip_binder().inputs()),
     };
     debug_assert!(!self_ty.has_escaping_bound_vars());
-    let trait_ref = ty::TraitRef {
-        def_id: fn_trait_def_id,
-        substs: tcx.mk_substs_trait(self_ty, &[arguments_tuple.into()]),
-    };
+    let trait_ref = tcx.mk_trait_ref(fn_trait_def_id, self_ty, &[arguments_tuple.into()]);
     sig.map_bound(|sig| (trait_ref, sig.output()))
 }
 
@@ -319,10 +315,8 @@ pub fn generator_trait_ref_and_outputs<'tcx>(
     sig: ty::PolyGenSig<'tcx>,
 ) -> ty::Binder<'tcx, (ty::TraitRef<'tcx>, Ty<'tcx>, Ty<'tcx>)> {
     debug_assert!(!self_ty.has_escaping_bound_vars());
-    let trait_ref = ty::TraitRef {
-        def_id: fn_trait_def_id,
-        substs: tcx.mk_substs_trait(self_ty, &[sig.skip_binder().resume_ty.into()]),
-    };
+    let trait_ref =
+        tcx.mk_trait_ref(fn_trait_def_id, self_ty, &[sig.skip_binder().resume_ty.into()]);
     sig.map_bound(|sig| (trait_ref, sig.yield_ty, sig.return_ty))
 }
 
diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs
index fce92c66ee8..3fe019cb7de 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -421,10 +421,11 @@ impl<'tcx> WfPredicates<'tcx> {
     fn require_sized(&mut self, subty: Ty<'tcx>, cause: traits::ObligationCauseCode<'tcx>) {
         if !subty.has_escaping_bound_vars() {
             let cause = self.cause(cause);
-            let trait_ref = ty::TraitRef {
-                def_id: self.tcx.require_lang_item(LangItem::Sized, None),
-                substs: self.tcx.mk_substs_trait(subty, &[]),
-            };
+            let trait_ref = self.tcx.mk_trait_ref(
+                self.tcx.require_lang_item(LangItem::Sized, None),
+                subty,
+                &[],
+            );
             self.out.push(traits::Obligation::with_depth(
                 self.tcx,
                 cause,