Move MatchAgainstFreshVars to old solver

compiler/rustc_infer/src/infer/relate/_match.rs

@@ -1,121 +0,0 @@
-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
-/// indicates if the non-freshened versions of A and B could have been
-/// unified.
-///
-/// It is only an approximation. If it yields false, unification would
-/// definitely fail, but a true result doesn't mean unification would
-/// succeed. This is because we don't track the "side-constraints" on
-/// type variables, nor do we track if the same freshened type appears
-/// more than once. To some extent these approximations could be
-/// fixed, given effort.
-///
-/// Like subtyping, matching is really a binary relation, so the only
-/// important thing about the result is Ok/Err. Also, matching never
-/// affects any type variables or unification state.
-pub struct MatchAgainstFreshVars<'tcx> {
-    tcx: TyCtxt<'tcx>,
-}
-
-impl<'tcx> MatchAgainstFreshVars<'tcx> {
-    pub fn new(tcx: TyCtxt<'tcx>) -> MatchAgainstFreshVars<'tcx> {
-        MatchAgainstFreshVars { tcx }
-    }
-}
-
-impl<'tcx> TypeRelation<TyCtxt<'tcx>> for MatchAgainstFreshVars<'tcx> {
-    fn tag(&self) -> &'static str {
-        "MatchAgainstFreshVars"
-    }
-
-    fn tcx(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    fn relate_with_variance<T: Relate<TyCtxt<'tcx>>>(
-        &mut self,
-        _: ty::Variance,
-        _: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
-        a: T,
-        b: T,
-    ) -> RelateResult<'tcx, T> {
-        self.relate(a, b)
-    }
-
-    #[instrument(skip(self), level = "debug")]
-    fn regions(
-        &mut self,
-        a: ty::Region<'tcx>,
-        _b: ty::Region<'tcx>,
-    ) -> RelateResult<'tcx, ty::Region<'tcx>> {
-        Ok(a)
-    }
-
-    #[instrument(skip(self), level = "debug")]
-    fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
-        if a == b {
-            return Ok(a);
-        }
-
-        match (a.kind(), b.kind()) {
-            (
-                _,
-                &ty::Infer(ty::FreshTy(_))
-                | &ty::Infer(ty::FreshIntTy(_))
-                | &ty::Infer(ty::FreshFloatTy(_)),
-            ) => Ok(a),
-
-            (&ty::Infer(_), _) | (_, &ty::Infer(_)) => {
-                Err(TypeError::Sorts(ExpectedFound::new(true, a, b)))
-            }
-
-            (&ty::Error(guar), _) | (_, &ty::Error(guar)) => Ok(Ty::new_error(self.tcx(), guar)),
-
-            _ => structurally_relate_tys(self, a, b),
-        }
-    }
-
-    fn consts(
-        &mut self,
-        a: ty::Const<'tcx>,
-        b: ty::Const<'tcx>,
-    ) -> RelateResult<'tcx, ty::Const<'tcx>> {
-        debug!("{}.consts({:?}, {:?})", self.tag(), a, b);
-        if a == b {
-            return Ok(a);
-        }
-
-        match (a.kind(), b.kind()) {
-            (_, ty::ConstKind::Infer(InferConst::Fresh(_))) => {
-                return Ok(a);
-            }
-
-            (ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => {
-                return Err(TypeError::ConstMismatch(ExpectedFound::new(true, a, b)));
-            }
-
-            _ => {}
-        }
-
-        relate::structurally_relate_consts(self, a, b)
-    }
-
-    fn binders<T>(
-        &mut self,
-        a: ty::Binder<'tcx, T>,
-        b: ty::Binder<'tcx, T>,
-    ) -> RelateResult<'tcx, ty::Binder<'tcx, T>>
-    where
-        T: Relate<TyCtxt<'tcx>>,
-    {
-        Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?))
-    }
-}

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;