Stop passing the self-type as a separate argument.

14 files changed, 46 insertions, 68 deletions

diff --git a/compiler/rustc_trait_selection/src/autoderef.rs b/compiler/rustc_trait_selection/src/autoderef.rs
index 415bd8de145..9b39a940114 100644
--- a/compiler/rustc_trait_selection/src/autoderef.rs
+++ b/compiler/rustc_trait_selection/src/autoderef.rs
@@ -122,7 +122,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
         let tcx = self.infcx.tcx;
 
         // <ty as Deref>
-        let trait_ref = tcx.mk_trait_ref(tcx.lang_items().deref_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 af17c86e1a5..25a9c29caa7 100644
--- a/compiler/rustc_trait_selection/src/infer.rs
+++ b/compiler/rustc_trait_selection/src/infer.rs
@@ -7,9 +7,8 @@ use rustc_infer::traits::ObligationCause;
 use rustc_middle::arena::ArenaAllocatable;
 use rustc_middle::infer::canonical::{Canonical, CanonicalizedQueryResponse, QueryResponse};
 use rustc_middle::traits::query::Fallible;
-use rustc_middle::ty::subst::SubstsRef;
-use rustc_middle::ty::ToPredicate;
 use rustc_middle::ty::{self, Ty, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{GenericArg, ToPredicate};
 use rustc_span::{Span, DUMMY_SP};
 
 use std::fmt::Debug;
@@ -44,8 +43,7 @@ pub trait InferCtxtExt<'tcx> {
     /// The inputs are:
     ///
     /// - the def-id of the trait
-    /// - the self type
-    /// - the *other* type parameters of the trait, excluding the self-type
+    /// - the type parameters of the trait, including the self-type
     /// - the parameter environment
     ///
     /// Invokes `evaluate_obligation`, so in the event that evaluating
@@ -54,8 +52,7 @@ pub trait InferCtxtExt<'tcx> {
     fn type_implements_trait(
         &self,
         trait_def_id: DefId,
-        ty: Ty<'tcx>,
-        params: SubstsRef<'tcx>,
+        params: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> traits::EvaluationResult;
 }
@@ -109,15 +106,14 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         InferOk { value, obligations }
     }
 
-    #[instrument(level = "debug", skip(self), ret)]
+    #[instrument(level = "debug", skip(self, params), ret)]
     fn type_implements_trait(
         &self,
         trait_def_id: DefId,
-        self_ty: Ty<'tcx>,
-        params: SubstsRef<'tcx>,
+        params: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> traits::EvaluationResult {
-        let trait_ref = self.tcx.mk_trait_ref(trait_def_id, self_ty, params);
+        let trait_ref = self.tcx.mk_trait_ref(trait_def_id, params);
 
         let obligation = traits::Obligation {
             cause: traits::ObligationCause::dummy(),
diff --git a/compiler/rustc_trait_selection/src/traits/auto_trait.rs b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
index c7dc7b1049c..a057e45ad6a 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 = tcx.mk_trait_ref(trait_did, ty, []);
+        let trait_ref = tcx.mk_trait_ref(trait_did, [ty]);
 
         let trait_pred = ty::Binder::dummy(trait_ref);
 
@@ -260,7 +260,7 @@ 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: infcx.tcx.mk_trait_ref(trait_did, ty, []),
+            trait_ref: infcx.tcx.mk_trait_ref(trait_did, [ty]),
 
             constness: ty::BoundConstness::NotConst,
             // Auto traits are positive
diff --git a/compiler/rustc_trait_selection/src/traits/engine.rs b/compiler/rustc_trait_selection/src/traits/engine.rs
index 09c2449bdae..3a05708aebc 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 = tcx.mk_trait_ref(def_id, 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 3d0f87942c3..946e6e77a3d 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -347,7 +347,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
                     span: DUMMY_SP,
                     kind: TypeVariableOriginKind::MiscVariable,
                 });
-                let trait_ref = self.tcx.mk_trait_ref(trait_def_id, ty.skip_binder(), [var.into()]);
+                let trait_ref = self.tcx.mk_trait_ref(trait_def_id, [ty.skip_binder(), var]);
                 let obligation = Obligation::new(
                     self.tcx,
                     ObligationCause::dummy(),
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 4b6d8177381..8086cac0d55 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -2971,8 +2971,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 let self_ty = self.resolve_vars_if_possible(trait_pred.self_ty());
                 let impls_future = self.type_implements_trait(
                     future_trait,
-                    self.tcx.erase_late_bound_regions(self_ty),
-                    ty::List::empty(),
+                    [self.tcx.erase_late_bound_regions(self_ty)],
                     obligation.param_env,
                 );
                 if !impls_future.must_apply_modulo_regions() {
@@ -3070,15 +3069,14 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     let field_ty = field.ty(self.tcx, substs);
                     let trait_substs = match diagnostic_name {
                         sym::PartialEq | sym::PartialOrd => {
-                            Some(field_ty.into())
+                            Some(field_ty)
                         }
                         _ => None,
                     };
                     let trait_pred = trait_pred.map_bound_ref(|tr| ty::TraitPredicate {
                         trait_ref: self.tcx.mk_trait_ref(
                             trait_pred.def_id(),
-                            field_ty,
-                            trait_substs,
+                            [field_ty].into_iter().chain(trait_substs),
                         ),
                         ..*tr
                     });
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index eb5cd9a2d06..ff18aa1f9e9 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -143,7 +143,7 @@ pub fn type_known_to_meet_bound_modulo_regions<'tcx>(
     def_id: DefId,
     span: Span,
 ) -> bool {
-    let trait_ref = ty::Binder::dummy(infcx.tcx.mk_trait_ref(def_id, 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)
 }
 
@@ -903,7 +903,7 @@ 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 = tcx.mk_trait_ref(unsize_trait_did, source, [target.into()]);
+    let trait_ref = tcx.mk_trait_ref(unsize_trait_did, [source, target]);
 
     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 29b315bff16..90f48658113 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -685,11 +685,9 @@ fn receiver_is_dispatchable<'tcx>(
         let param_env = tcx.param_env(method.def_id);
 
         // Self: Unsize<U>
-        let unsize_predicate = ty::Binder::dummy(tcx.mk_trait_ref(
-            unsize_did,
-            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]),
+        )
         .without_const()
         .to_predicate(tcx);
 
@@ -721,11 +719,9 @@ fn receiver_is_dispatchable<'tcx>(
 
     // Receiver: DispatchFromDyn<Receiver[Self => U]>
     let obligation = {
-        let predicate = ty::Binder::dummy(tcx.mk_trait_ref(
-            dispatch_from_dyn_did,
-            receiver_ty,
-            [unsized_receiver_ty.into()],
-        ))
+        let predicate = ty::Binder::dummy(
+            tcx.mk_trait_ref(dispatch_from_dyn_did, [receiver_ty, unsized_receiver_ty]),
+        )
         .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 4b1e8f18e34..9f19b0092c0 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1712,7 +1712,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                                 selcx.tcx(),
                                 ty::Binder::dummy(selcx.tcx().at(obligation.cause.span).mk_trait_ref(
                                     LangItem::Sized,
-                                    self_ty, [],
+                                    [self_ty],
                                 ))
                                 .without_const(),
                             ),
@@ -1966,11 +1966,9 @@ fn confirm_pointee_candidate<'cx, 'tcx>(
         )
     });
     if check_is_sized {
-        let sized_predicate = ty::Binder::dummy(tcx.at(obligation.cause.span).mk_trait_ref(
-            LangItem::Sized,
-            self_ty,
-            [],
-        ))
+        let sized_predicate = ty::Binder::dummy(
+            tcx.at(obligation.cause.span).mk_trait_ref(LangItem::Sized, [self_ty]),
+        )
         .without_const();
         obligations.push(obligation.with(tcx, sized_predicate));
     }
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 b11f2c8e6a4..99d4e47ffc1 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -714,7 +714,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
 
         // <ty as Deref>
-        let trait_ref = tcx.mk_trait_ref(tcx.lang_items().deref_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 19d69e9dfaa..2ec5d925b69 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -632,11 +632,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             output_ty,
             &mut nested,
         );
-        let tr = ty::Binder::dummy(self.tcx().at(cause.span).mk_trait_ref(
-            LangItem::Sized,
-            output_ty,
-            [],
-        ));
+        let tr =
+            ty::Binder::dummy(self.tcx().at(cause.span).mk_trait_ref(LangItem::Sized, [output_ty]));
         nested.push(Obligation::new(
             self.infcx.tcx,
             cause,
@@ -998,7 +995,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
                 // We can only make objects from sized types.
                 let tr =
-                    ty::Binder::dummy(tcx.at(cause.span).mk_trait_ref(LangItem::Sized, source, []));
+                    ty::Binder::dummy(tcx.at(cause.span).mk_trait_ref(LangItem::Sized, [source]));
                 nested.push(predicate_to_obligation(tr.without_const().to_predicate(tcx)));
 
                 // If the type is `Foo + 'a`, ensure that the type
@@ -1104,8 +1101,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     obligation.cause.clone(),
                     obligation.predicate.def_id(),
                     obligation.recursion_depth + 1,
-                    source_tail,
-                    [target_tail.into()],
+                    [source_tail, target_tail],
                 ));
             }
 
@@ -1135,8 +1131,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         obligation.cause.clone(),
                         obligation.predicate.def_id(),
                         obligation.recursion_depth + 1,
-                        a_last,
-                        [b_last.into()],
+                        [a_last, b_last],
                     )
                 }));
             }
@@ -1252,11 +1247,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         cause.clone(),
                         obligation.recursion_depth + 1,
                         self_ty.rebind(ty::TraitPredicate {
-                            trait_ref: self.tcx().at(cause.span).mk_trait_ref(
-                                LangItem::Destruct,
-                                nested_ty,
-                                [],
-                            ),
+                            trait_ref: self
+                                .tcx()
+                                .at(cause.span)
+                                .mk_trait_ref(LangItem::Destruct, [nested_ty]),
                             constness: ty::BoundConstness::ConstIfConst,
                             polarity: ty::ImplPolarity::Positive,
                         }),
@@ -1277,11 +1271,10 @@ 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: self.tcx().at(cause.span).mk_trait_ref(
-                            LangItem::Destruct,
-                            nested_ty,
-                            [],
-                        ),
+                        trait_ref: self
+                            .tcx()
+                            .at(cause.span)
+                            .mk_trait_ref(LangItem::Destruct, [nested_ty]),
                         constness: ty::BoundConstness::ConstIfConst,
                         polarity: ty::ImplPolarity::Positive,
                     });
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 06e507eb729..e54e290fb4b 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -2100,8 +2100,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     cause.clone(),
                     trait_def_id,
                     recursion_depth,
-                    normalized_ty,
-                    [],
+                    [normalized_ty],
                 );
                 obligations.push(placeholder_obligation);
                 obligations
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index 87c534bad96..895b84fd7e9 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -238,10 +238,9 @@ pub fn predicate_for_trait_def<'tcx>(
     cause: ObligationCause<'tcx>,
     trait_def_id: DefId,
     recursion_depth: usize,
-    self_ty: Ty<'tcx>,
-    params: impl IntoIterator<Item = GenericArg<'tcx>, IntoIter: ExactSizeIterator>,
+    params: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
 ) -> PredicateObligation<'tcx> {
-    let trait_ref = tcx.mk_trait_ref(trait_def_id, self_ty, params);
+    let trait_ref = tcx.mk_trait_ref(trait_def_id, params);
     predicate_for_trait_ref(tcx, cause, param_env, trait_ref, recursion_depth)
 }
 
@@ -304,7 +303,7 @@ 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 = tcx.mk_trait_ref(fn_trait_def_id, self_ty, [arguments_tuple.into()]);
+    let trait_ref = tcx.mk_trait_ref(fn_trait_def_id, [self_ty, arguments_tuple]);
     sig.map_bound(|sig| (trait_ref, sig.output()))
 }
 
@@ -315,8 +314,7 @@ 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 =
-        tcx.mk_trait_ref(fn_trait_def_id, 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]);
     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 de72c6618d4..53783e1bc4b 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -421,7 +421,7 @@ 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 = self.tcx.at(cause.span).mk_trait_ref(LangItem::Sized, subty, []);
+            let trait_ref = self.tcx.at(cause.span).mk_trait_ref(LangItem::Sized, [subty]);
             self.out.push(traits::Obligation::with_depth(
                 self.tcx,
                 cause,