4 files changed, 90 insertions, 10 deletions
diff --git a/compiler/rustc_next_trait_solver/src/canonicalizer.rs b/compiler/rustc_next_trait_solver/src/canonicalizer.rs
index f22e24ef654..a81fd03d034 100644
--- a/compiler/rustc_next_trait_solver/src/canonicalizer.rs
+++ b/compiler/rustc_next_trait_solver/src/canonicalizer.rs
@@ -4,10 +4,11 @@ use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::visit::TypeVisitableExt;
 use rustc_type_ir::{
-    self as ty, Canonical, CanonicalTyVarKind, CanonicalVarInfo, CanonicalVarKind, InferCtxtLike,
-    Interner,
+    self as ty, Canonical, CanonicalTyVarKind, CanonicalVarInfo, CanonicalVarKind, Interner,
 };
 
+use crate::infcx::SolverDelegate;
+
 /// Whether we're canonicalizing a query input or the query response.
 ///
 /// When canonicalizing an input we're in the context of the caller
@@ -37,7 +38,7 @@ pub enum CanonicalizeMode {
     },
 }
 
-pub struct Canonicalizer<'a, Infcx: InferCtxtLike<Interner = I>, I: Interner> {
+pub struct Canonicalizer<'a, Infcx: SolverDelegate<Interner = I>, I: Interner> {
     infcx: &'a Infcx,
     canonicalize_mode: CanonicalizeMode,
 
@@ -46,7 +47,7 @@ pub struct Canonicalizer<'a, Infcx: InferCtxtLike<Interner = I>, I: Interner> {
     binder_index: ty::DebruijnIndex,
 }
 
-impl<'a, Infcx: InferCtxtLike<Interner = I>, I: Interner> Canonicalizer<'a, Infcx, I> {
+impl<'a, Infcx: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, Infcx, I> {
     pub fn canonicalize<T: TypeFoldable<I>>(
         infcx: &'a Infcx,
         canonicalize_mode: CanonicalizeMode,
@@ -210,7 +211,7 @@ impl<'a, Infcx: InferCtxtLike<Interner = I>, I: Interner> Canonicalizer<'a, Infc
     }
 }
 
-impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeFolder<I>
+impl<Infcx: SolverDelegate<Interner = I>, I: Interner> TypeFolder<I>
     for Canonicalizer<'_, Infcx, I>
 {
     fn interner(&self) -> I {
diff --git a/compiler/rustc_next_trait_solver/src/infcx.rs b/compiler/rustc_next_trait_solver/src/infcx.rs
new file mode 100644
index 00000000000..cb46d8f8f73
--- /dev/null
+++ b/compiler/rustc_next_trait_solver/src/infcx.rs
@@ -0,0 +1,77 @@
+use rustc_type_ir::fold::TypeFoldable;
+use rustc_type_ir::relate::Relate;
+use rustc_type_ir::solve::{Goal, NoSolution};
+use rustc_type_ir::{self as ty, Interner};
+
+pub trait SolverDelegate: Sized {
+    type Interner: Interner;
+
+    fn interner(&self) -> Self::Interner;
+
+    fn universe_of_ty(&self, ty: ty::TyVid) -> Option<ty::UniverseIndex>;
+    fn universe_of_lt(&self, lt: ty::RegionVid) -> Option<ty::UniverseIndex>;
+    fn universe_of_ct(&self, ct: ty::ConstVid) -> Option<ty::UniverseIndex>;
+
+    fn root_ty_var(&self, var: ty::TyVid) -> ty::TyVid;
+    fn root_const_var(&self, var: ty::ConstVid) -> ty::ConstVid;
+
+    fn opportunistic_resolve_ty_var(&self, vid: ty::TyVid) -> <Self::Interner as Interner>::Ty;
+    fn opportunistic_resolve_int_var(&self, vid: ty::IntVid) -> <Self::Interner as Interner>::Ty;
+    fn opportunistic_resolve_float_var(
+        &self,
+        vid: ty::FloatVid,
+    ) -> <Self::Interner as Interner>::Ty;
+    fn opportunistic_resolve_ct_var(
+        &self,
+        vid: ty::ConstVid,
+    ) -> <Self::Interner as Interner>::Const;
+    fn opportunistic_resolve_effect_var(
+        &self,
+        vid: ty::EffectVid,
+    ) -> <Self::Interner as Interner>::Const;
+    fn opportunistic_resolve_lt_var(
+        &self,
+        vid: ty::RegionVid,
+    ) -> <Self::Interner as Interner>::Region;
+
+    fn defining_opaque_types(&self) -> <Self::Interner as Interner>::DefiningOpaqueTypes;
+
+    fn next_ty_infer(&self) -> <Self::Interner as Interner>::Ty;
+    fn next_const_infer(&self) -> <Self::Interner as Interner>::Const;
+    fn fresh_args_for_item(
+        &self,
+        def_id: <Self::Interner as Interner>::DefId,
+    ) -> <Self::Interner as Interner>::GenericArgs;
+
+    fn instantiate_binder_with_infer<T: TypeFoldable<Self::Interner> + Copy>(
+        &self,
+        value: ty::Binder<Self::Interner, T>,
+    ) -> T;
+
+    fn enter_forall<T: TypeFoldable<Self::Interner> + Copy, U>(
+        &self,
+        value: ty::Binder<Self::Interner, T>,
+        f: impl FnOnce(T) -> U,
+    ) -> U;
+
+    fn relate<T: Relate<Self::Interner>>(
+        &self,
+        param_env: <Self::Interner as Interner>::ParamEnv,
+        lhs: T,
+        variance: ty::Variance,
+        rhs: T,
+    ) -> Result<Vec<Goal<Self::Interner, <Self::Interner as Interner>::Predicate>>, NoSolution>;
+
+    fn eq_structurally_relating_aliases<T: Relate<Self::Interner>>(
+        &self,
+        param_env: <Self::Interner as Interner>::ParamEnv,
+        lhs: T,
+        rhs: T,
+    ) -> Result<Vec<Goal<Self::Interner, <Self::Interner as Interner>::Predicate>>, NoSolution>;
+
+    fn resolve_vars_if_possible<T>(&self, value: T) -> T
+    where
+        T: TypeFoldable<Self::Interner>;
+
+    fn probe<T>(&self, probe: impl FnOnce() -> T) -> T;
+}
diff --git a/compiler/rustc_next_trait_solver/src/lib.rs b/compiler/rustc_next_trait_solver/src/lib.rs
index 144caf36ee5..ea3e18872fa 100644
--- a/compiler/rustc_next_trait_solver/src/lib.rs
+++ b/compiler/rustc_next_trait_solver/src/lib.rs
@@ -5,5 +5,6 @@
 //! So if you got to this crate from the old solver, it's totally normal.
 
 pub mod canonicalizer;
+pub mod infcx;
 pub mod resolve;
 pub mod solve;
diff --git a/compiler/rustc_next_trait_solver/src/resolve.rs b/compiler/rustc_next_trait_solver/src/resolve.rs
index 5c00b6978d6..3d8d957eaae 100644
--- a/compiler/rustc_next_trait_solver/src/resolve.rs
+++ b/compiler/rustc_next_trait_solver/src/resolve.rs
@@ -1,27 +1,28 @@
+use crate::infcx::SolverDelegate;
 use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::visit::TypeVisitableExt;
-use rustc_type_ir::{self as ty, InferCtxtLike, Interner};
+use rustc_type_ir::{self as ty, Interner};
 
 ///////////////////////////////////////////////////////////////////////////
 // EAGER RESOLUTION
 
 /// Resolves ty, region, and const vars to their inferred values or their root vars.
-pub struct EagerResolver<'a, Infcx, I = <Infcx as InferCtxtLike>::Interner>
+pub struct EagerResolver<'a, Infcx, I = <Infcx as SolverDelegate>::Interner>
 where
-    Infcx: InferCtxtLike<Interner = I>,
+    Infcx: SolverDelegate<Interner = I>,
     I: Interner,
 {
     infcx: &'a Infcx,
 }
 
-impl<'a, Infcx: InferCtxtLike> EagerResolver<'a, Infcx> {
+impl<'a, Infcx: SolverDelegate> EagerResolver<'a, Infcx> {
     pub fn new(infcx: &'a Infcx) -> Self {
         EagerResolver { infcx }
     }
 }
 
-impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeFolder<I> for EagerResolver<'_, Infcx> {
+impl<Infcx: SolverDelegate<Interner = I>, I: Interner> TypeFolder<I> for EagerResolver<'_, Infcx> {
     fn interner(&self) -> I {
         self.infcx.interner()
     }