3 files changed, 8 insertions, 18 deletions
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index b8748ec6581..d61ef7641ee 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -551,7 +551,7 @@ pub struct DerivedCause<'tcx> {
     pub parent_code: InternedObligationCauseCode<'tcx>,
 }
 
-#[derive(Clone, Debug, TypeVisitable)]
+#[derive(Clone, Debug, PartialEq, Eq, TypeVisitable)]
 pub enum SelectionError<'tcx> {
     /// The trait is not implemented.
     Unimplemented,
@@ -573,7 +573,7 @@ pub enum SelectionError<'tcx> {
     ConstArgHasWrongType { ct: ty::Const<'tcx>, ct_ty: Ty<'tcx>, expected_ty: Ty<'tcx> },
 }
 
-#[derive(Clone, Debug, TypeVisitable)]
+#[derive(Clone, Debug, PartialEq, Eq, TypeVisitable)]
 pub struct SignatureMismatchData<'tcx> {
     pub found_trait_ref: ty::TraitRef<'tcx>,
     pub expected_trait_ref: ty::TraitRef<'tcx>,
diff --git a/compiler/rustc_middle/src/traits/select.rs b/compiler/rustc_middle/src/traits/select.rs
index 05556ae38a8..094fc62afbb 100644
--- a/compiler/rustc_middle/src/traits/select.rs
+++ b/compiler/rustc_middle/src/traits/select.rs
@@ -11,20 +11,10 @@ use self::EvaluationResult::*;
 use super::{SelectionError, SelectionResult};
 use crate::ty;
 
-pub type SelectionCache<'tcx> = Cache<
-    // This cache does not use `ParamEnvAnd` in its keys because `ParamEnv::and` can replace
-    // caller bounds with an empty list if the `TraitPredicate` looks global, which may happen
-    // after erasing lifetimes from the predicate.
-    (ty::ParamEnv<'tcx>, ty::TraitPredicate<'tcx>),
-    SelectionResult<'tcx, SelectionCandidate<'tcx>>,
->;
-
-pub type EvaluationCache<'tcx> = Cache<
-    // See above: this cache does not use `ParamEnvAnd` in its keys due to sometimes incorrectly
-    // caching with the wrong `ParamEnv`.
-    (ty::ParamEnv<'tcx>, ty::PolyTraitPredicate<'tcx>),
-    EvaluationResult,
->;
+pub type SelectionCache<'tcx, ENV> =
+    Cache<(ENV, ty::TraitPredicate<'tcx>), SelectionResult<'tcx, SelectionCandidate<'tcx>>>;
+
+pub type EvaluationCache<'tcx, ENV> = Cache<(ENV, ty::PolyTraitPredicate<'tcx>), EvaluationResult>;
 
 /// The selection process begins by considering all impls, where
 /// clauses, and so forth that might resolve an obligation. Sometimes
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 1bd19a6031a..d982122e2aa 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1326,12 +1326,12 @@ pub struct GlobalCtxt<'tcx> {
 
     /// Caches the results of trait selection. This cache is used
     /// for things that do not have to do with the parameters in scope.
-    pub selection_cache: traits::SelectionCache<'tcx>,
+    pub selection_cache: traits::SelectionCache<'tcx, ty::TypingEnv<'tcx>>,
 
     /// Caches the results of trait evaluation. This cache is used
     /// for things that do not have to do with the parameters in scope.
     /// Merge this with `selection_cache`?
-    pub evaluation_cache: traits::EvaluationCache<'tcx>,
+    pub evaluation_cache: traits::EvaluationCache<'tcx, ty::TypingEnv<'tcx>>,
 
     /// Caches the results of goal evaluation in the new solver.
     pub new_solver_evaluation_cache: Lock<search_graph::GlobalCache<TyCtxt<'tcx>>>,