6 files changed, 20 insertions, 8 deletions
diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs
index 7c90cbb9092..c1ec5d68a7b 100644
--- a/compiler/rustc_middle/src/arena.rs
+++ b/compiler/rustc_middle/src/arena.rs
@@ -85,6 +85,7 @@ macro_rules! arena_types {
             [] attribute: rustc_ast::Attribute,
             [] name_set: rustc_data_structures::fx::FxHashSet<rustc_span::symbol::Symbol>,
             [] hir_id_set: rustc_hir::HirIdSet,
+            [] late_bound_lifetimes: rustc_data_structures::fx::FxIndexSet<rustc_hir::def_id::LocalDefId>,
 
             // Interned types
             [] tys: rustc_data_structures::intern::WithStableHash<rustc_middle::ty::TyS<'tcx>>,
diff --git a/compiler/rustc_middle/src/middle/resolve_lifetime.rs b/compiler/rustc_middle/src/middle/resolve_lifetime.rs
index 70586cefaee..11ce6313147 100644
--- a/compiler/rustc_middle/src/middle/resolve_lifetime.rs
+++ b/compiler/rustc_middle/src/middle/resolve_lifetime.rs
@@ -2,7 +2,7 @@
 
 use crate::ty;
 
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::ItemLocalId;
 use rustc_macros::HashStable;
@@ -64,7 +64,7 @@ pub struct ResolveLifetimes {
     /// Set of lifetime def ids that are late-bound; a region can
     /// be late-bound if (a) it does NOT appear in a where-clause and
     /// (b) it DOES appear in the arguments.
-    pub late_bound: FxHashMap<LocalDefId, FxHashSet<LocalDefId>>,
+    pub late_bound: FxHashMap<LocalDefId, FxIndexSet<LocalDefId>>,
 
     pub late_bound_vars: FxHashMap<LocalDefId, FxHashMap<ItemLocalId, Vec<ty::BoundVariableKind>>>,
 }
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 6d7ec247d04..a23ff302a40 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -1537,7 +1537,7 @@ rustc_queries! {
         Option<&'tcx FxHashMap<ItemLocalId, Region>> {
         desc { "looking up a named region" }
     }
-    query is_late_bound_map(_: LocalDefId) -> Option<(LocalDefId, &'tcx FxHashSet<LocalDefId>)> {
+    query is_late_bound_map(_: LocalDefId) -> Option<(LocalDefId, &'tcx FxIndexSet<LocalDefId>)> {
         desc { "testing if a region is late bound" }
     }
     /// For a given item (like a struct), gets the default lifetimes to be used
diff --git a/compiler/rustc_middle/src/traits/select.rs b/compiler/rustc_middle/src/traits/select.rs
index ffa70cddbd5..854dd215a37 100644
--- a/compiler/rustc_middle/src/traits/select.rs
+++ b/compiler/rustc_middle/src/traits/select.rs
@@ -176,6 +176,10 @@ pub enum EvaluationResult {
     EvaluatedToOk,
     /// Evaluation successful, but there were unevaluated region obligations.
     EvaluatedToOkModuloRegions,
+    /// Evaluation successful, but need to rerun because opaque types got
+    /// hidden types assigned without it being known whether the opaque types
+    /// are within their defining scope
+    EvaluatedToOkModuloOpaqueTypes,
     /// Evaluation is known to be ambiguous -- it *might* hold for some
     /// assignment of inference variables, but it might not.
     ///
@@ -252,9 +256,11 @@ impl EvaluationResult {
 
     pub fn may_apply(self) -> bool {
         match self {
-            EvaluatedToOk | EvaluatedToOkModuloRegions | EvaluatedToAmbig | EvaluatedToUnknown => {
-                true
-            }
+            EvaluatedToOkModuloOpaqueTypes
+            | EvaluatedToOk
+            | EvaluatedToOkModuloRegions
+            | EvaluatedToAmbig
+            | EvaluatedToUnknown => true,
 
             EvaluatedToErr | EvaluatedToRecur => false,
         }
@@ -264,7 +270,11 @@ impl EvaluationResult {
         match self {
             EvaluatedToUnknown | EvaluatedToRecur => true,
 
-            EvaluatedToOk | EvaluatedToOkModuloRegions | EvaluatedToAmbig | EvaluatedToErr => false,
+            EvaluatedToOkModuloOpaqueTypes
+            | EvaluatedToOk
+            | EvaluatedToOkModuloRegions
+            | EvaluatedToAmbig
+            | EvaluatedToErr => false,
         }
     }
 }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 1c552591b11..a254979162e 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1065,6 +1065,7 @@ impl<'tcx> InstantiatedPredicates<'tcx> {
     Lift
 )]
 pub struct OpaqueTypeKey<'tcx> {
+    // FIXME(oli-obk): make this a LocalDefId
     pub def_id: DefId,
     pub substs: SubstsRef<'tcx>,
 }
diff --git a/compiler/rustc_middle/src/ty/query.rs b/compiler/rustc_middle/src/ty/query.rs
index fb937ded65a..1bb49a59ba4 100644
--- a/compiler/rustc_middle/src/ty/query.rs
+++ b/compiler/rustc_middle/src/ty/query.rs
@@ -36,7 +36,7 @@ use crate::ty::{self, AdtSizedConstraint, CrateInherentImpls, ParamEnvAnd, Ty, T
 use rustc_ast as ast;
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_attr as attr;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::Lrc;