1 files changed, 17 insertions, 16 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/chalk_fulfill.rs b/compiler/rustc_trait_selection/src/traits/chalk_fulfill.rs
index 81e1d6449..e88950523 100644
--- a/compiler/rustc_trait_selection/src/traits/chalk_fulfill.rs
+++ b/compiler/rustc_trait_selection/src/traits/chalk_fulfill.rs
@@ -4,44 +4,43 @@ use crate::infer::canonical::OriginalQueryValues;
 use crate::infer::InferCtxt;
 use crate::traits::query::NoSolution;
 use crate::traits::{
-    ChalkEnvironmentAndGoal, FulfillmentError, FulfillmentErrorCode, ObligationCause,
-    PredicateObligation, SelectionError, TraitEngine,
+    ChalkEnvironmentAndGoal, FulfillmentError, FulfillmentErrorCode, PredicateObligation,
+    SelectionError, TraitEngine,
 };
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
-use rustc_middle::ty::{self, Ty, TypeVisitable};
+use rustc_middle::ty::{self, TypeVisitable};
 
 pub struct FulfillmentContext<'tcx> {
     obligations: FxIndexSet<PredicateObligation<'tcx>>,
 
     relationships: FxHashMap<ty::TyVid, ty::FoundRelationships>,
+
+    usable_in_snapshot: bool,
 }
 
 impl FulfillmentContext<'_> {
-    pub(crate) fn new() -> Self {
+    pub(super) fn new() -> Self {
         FulfillmentContext {
             obligations: FxIndexSet::default(),
             relationships: FxHashMap::default(),
+            usable_in_snapshot: false,
         }
     }
-}
 
-impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
-    fn normalize_projection_type(
-        &mut self,
-        infcx: &InferCtxt<'tcx>,
-        _param_env: ty::ParamEnv<'tcx>,
-        projection_ty: ty::ProjectionTy<'tcx>,
-        _cause: ObligationCause<'tcx>,
-    ) -> Ty<'tcx> {
-        infcx.tcx.mk_ty(ty::Projection(projection_ty))
+    pub(crate) fn new_in_snapshot() -> Self {
+        FulfillmentContext { usable_in_snapshot: true, ..Self::new() }
     }
+}
 
+impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
     fn register_predicate_obligation(
         &mut self,
         infcx: &InferCtxt<'tcx>,
         obligation: PredicateObligation<'tcx>,
     ) {
-        assert!(!infcx.is_in_snapshot());
+        if !self.usable_in_snapshot {
+            assert!(!infcx.is_in_snapshot());
+        }
         let obligation = infcx.resolve_vars_if_possible(obligation);
 
         super::relationships::update(self, infcx, &obligation);
@@ -72,7 +71,9 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
     }
 
     fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>> {
-        assert!(!infcx.is_in_snapshot());
+        if !self.usable_in_snapshot {
+            assert!(!infcx.is_in_snapshot());
+        }
 
         let mut errors = Vec::new();
         let mut next_round = FxIndexSet::default();