From b0eaaca31457672a8022312cc0f89b18ebc9d754 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 5 Jun 2023 20:05:08 +0000
Subject: [PATCH] Remove redundant InferCtxtExt::fresh_item_substs

---
 .../rustc_hir_analysis/src/astconv/mod.rs     | 37 +------------------
 compiler/rustc_hir_typeck/src/method/probe.rs |  5 +--
 .../rustc_infer/src/infer/type_variable.rs    |  1 -
 compiler/rustc_middle/src/infer/unify_key.rs  |  1 -
 4 files changed, 3 insertions(+), 41 deletions(-)

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 37f176579611..8d3c0a4fb9e2 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -26,10 +26,8 @@ use rustc_hir::def::{CtorOf, DefKind, Namespace, Res};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::{walk_generics, Visitor as _};
 use rustc_hir::{GenericArg, GenericArgs, OpaqueTyOrigin};
-use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::ObligationCause;
-use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_middle::middle::stability::AllowUnstable;
 use rustc_middle::ty::fold::FnMutDelegate;
 use rustc_middle::ty::subst::{self, GenericArgKind, InternalSubsts, SubstsRef};
@@ -2488,7 +2486,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     infcx.probe(|_| {
                         let ocx = ObligationCtxt::new_in_snapshot(&infcx);
 
-                        let impl_substs = infcx.fresh_item_substs(impl_);
+                        let impl_substs = infcx.fresh_substs_for_item(span, impl_);
                         let impl_ty = tcx.type_of(impl_).subst(tcx, impl_substs);
                         let impl_ty = ocx.normalize(&cause, param_env, impl_ty);
 
@@ -3775,36 +3773,3 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         }
     }
 }
-
-pub trait InferCtxtExt<'tcx> {
-    fn fresh_item_substs(&self, def_id: DefId) -> SubstsRef<'tcx>;
-}
-
-impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
-    fn fresh_item_substs(&self, def_id: DefId) -> SubstsRef<'tcx> {
-        InternalSubsts::for_item(self.tcx, def_id, |param, _| match param.kind {
-            GenericParamDefKind::Lifetime => self.tcx.lifetimes.re_erased.into(),
-            GenericParamDefKind::Type { .. } => self
-                .next_ty_var(TypeVariableOrigin {
-                    kind: TypeVariableOriginKind::SubstitutionPlaceholder,
-                    span: self.tcx.def_span(def_id),
-                })
-                .into(),
-            GenericParamDefKind::Const { .. } => {
-                let span = self.tcx.def_span(def_id);
-                let origin = ConstVariableOrigin {
-                    kind: ConstVariableOriginKind::SubstitutionPlaceholder,
-                    span,
-                };
-                self.next_const_var(
-                    self.tcx
-                        .type_of(param.def_id)
-                        .no_bound_vars()
-                        .expect("const parameter types cannot be generic"),
-                    origin,
-                )
-                .into()
-            }
-        })
-    }
-}
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 9f3d35a77dc7..b7b11ff8942f 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -9,7 +9,6 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
-use rustc_hir_analysis::astconv::InferCtxtExt as _;
 use rustc_hir_analysis::autoderef::{self, Autoderef};
 use rustc_infer::infer::canonical::OriginalQueryValues;
 use rustc_infer::infer::canonical::{Canonical, QueryResponse};
@@ -954,7 +953,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         trait_def_id: DefId,
     ) {
         debug!("assemble_extension_candidates_for_trait(trait_def_id={:?})", trait_def_id);
-        let trait_substs = self.fresh_item_substs(trait_def_id);
+        let trait_substs = self.fresh_substs_for_item(self.span, trait_def_id);
         let trait_ref = ty::TraitRef::new(self.tcx, trait_def_id, trait_substs);
 
         if self.tcx.is_trait_alias(trait_def_id) {
@@ -1899,7 +1898,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         &self,
         impl_def_id: DefId,
     ) -> (ty::EarlyBinder<Ty<'tcx>>, SubstsRef<'tcx>) {
-        (self.tcx.type_of(impl_def_id), self.fresh_item_substs(impl_def_id))
+        (self.tcx.type_of(impl_def_id), self.fresh_substs_for_item(self.span, impl_def_id))
     }
 
     /// Replaces late-bound-regions bound by `value` with `'static` using
diff --git a/compiler/rustc_infer/src/infer/type_variable.rs b/compiler/rustc_infer/src/infer/type_variable.rs
index f7ab05b2d498..9f85f9207e8f 100644
--- a/compiler/rustc_infer/src/infer/type_variable.rs
+++ b/compiler/rustc_infer/src/infer/type_variable.rs
@@ -129,7 +129,6 @@ pub enum TypeVariableOriginKind {
     /// (before it has been determined).
     // FIXME(eddyb) distinguish upvar inference variables from the rest.
     ClosureSynthetic,
-    SubstitutionPlaceholder,
     AutoDeref,
     AdjustmentType,
 
diff --git a/compiler/rustc_middle/src/infer/unify_key.rs b/compiler/rustc_middle/src/infer/unify_key.rs
index a873854f0686..991b9f01985c 100644
--- a/compiler/rustc_middle/src/infer/unify_key.rs
+++ b/compiler/rustc_middle/src/infer/unify_key.rs
@@ -116,7 +116,6 @@ pub enum ConstVariableOriginKind {
     MiscVariable,
     ConstInference,
     ConstParameterDefinition(Symbol, DefId),
-    SubstitutionPlaceholder,
 }
 
 #[derive(Copy, Clone, Debug)]