From 4b809b9438e891ce28dbf90059f1149a7a5f19a2 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 12 Jun 2024 16:22:49 -0400
Subject: [PATCH] Move MatchAgainstFreshVars to old solver

---
 compiler/rustc_infer/src/infer/relate/mod.rs                | 2 --
 .../src/traits/select}/_match.rs                            | 6 +++---
 compiler/rustc_trait_selection/src/traits/select/mod.rs     | 4 ++--
 3 files changed, 5 insertions(+), 7 deletions(-)
 rename compiler/{rustc_infer/src/infer/relate => rustc_trait_selection/src/traits/select}/_match.rs (97%)

diff --git a/compiler/rustc_infer/src/infer/relate/mod.rs b/compiler/rustc_infer/src/infer/relate/mod.rs
index e7b50479b85..41cc945492d 100644
--- a/compiler/rustc_infer/src/infer/relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/relate/mod.rs
@@ -4,11 +4,9 @@
 
 pub use rustc_middle::ty::relate::*;
 
-pub use self::_match::MatchAgainstFreshVars;
 pub use self::combine::CombineFields;
 pub use self::combine::PredicateEmittingRelation;
 
-pub mod _match;
 pub(super) mod combine;
 mod generalize;
 mod glb;
diff --git a/compiler/rustc_infer/src/infer/relate/_match.rs b/compiler/rustc_trait_selection/src/traits/select/_match.rs
similarity index 97%
rename from compiler/rustc_infer/src/infer/relate/_match.rs
rename to compiler/rustc_trait_selection/src/traits/select/_match.rs
index 30a066a265a..50d8e96aaf9 100644
--- a/compiler/rustc_infer/src/infer/relate/_match.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/_match.rs
@@ -1,10 +1,10 @@
+use rustc_infer::infer::relate::{
+    self, structurally_relate_tys, Relate, RelateResult, TypeRelation,
+};
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::{self, InferConst, Ty, TyCtxt};
 use tracing::{debug, instrument};
 
-use super::{structurally_relate_tys, Relate, RelateResult, TypeRelation};
-use crate::infer::relate;
-
 /// A type "A" *matches* "B" if the fresh types in B could be
 /// instantiated with values so as to make it equal to A. Matching is
 /// intended to be used only on freshened types, and it basically
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 4306a803524..42998fbd862 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -32,7 +32,6 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::{Diag, EmissionGuarantee};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_infer::infer::relate::MatchAgainstFreshVars;
 use rustc_infer::infer::relate::TypeRelation;
 use rustc_infer::infer::BoundRegionConversionTime;
 use rustc_infer::infer::BoundRegionConversionTime::HigherRankedType;
@@ -60,6 +59,7 @@ use std::ops::ControlFlow;
 pub use rustc_middle::traits::select::*;
 use rustc_middle::ty::print::with_no_trimmed_paths;
 
+mod _match;
 mod candidate_assembly;
 mod confirmation;
 
@@ -2719,7 +2719,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         previous: ty::PolyTraitPredicate<'tcx>,
         current: ty::PolyTraitPredicate<'tcx>,
     ) -> bool {
-        let mut matcher = MatchAgainstFreshVars::new(self.tcx());
+        let mut matcher = _match::MatchAgainstFreshVars::new(self.tcx());
         matcher.relate(previous, current).is_ok()
     }