[HACK] Binderize ProjectionCacheKey.

Author: eddyb

compiler/rustc_infer/src/traits/project.rs

@@ -77,11 +77,11 @@ pub struct ProjectionCacheStorage<'tcx> {
 
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
 pub struct ProjectionCacheKey<'tcx> {
-    ty: ty::ProjectionTy<'tcx>,
+    ty: ty::Binder<'tcx, ty::ProjectionTy<'tcx>>,
 }
 
 impl<'tcx> ProjectionCacheKey<'tcx> {
-    pub fn new(ty: ty::ProjectionTy<'tcx>) -> Self {
+    pub fn new(ty: ty::Binder<'tcx, ty::ProjectionTy<'tcx>>) -> Self {
         Self { ty }
     }
 }

compiler/rustc_trait_selection/src/traits/project.rs

@@ -958,7 +958,7 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
     let use_cache = !selcx.is_intercrate();
 
     let projection_ty = infcx.resolve_vars_if_possible(projection_ty);
-    let cache_key = ProjectionCacheKey::new(projection_ty);
+    let cache_key = ProjectionCacheKey::new(ty::Binder::dummy(projection_ty));
 
     // FIXME(#20304) For now, I am caching here, which is good, but it
     // means we don't capture the type variables that are created in
@@ -2123,14 +2123,12 @@ impl<'cx, 'tcx> ProjectionCacheKeyExt<'cx, 'tcx> for ProjectionCacheKey<'tcx> {
         let infcx = selcx.infcx();
         // We don't do cross-snapshot caching of obligations with escaping regions,
         // so there's no cache key to use
-        predicate.no_bound_vars().map(|predicate| {
-            ProjectionCacheKey::new(
-                // We don't attempt to match up with a specific type-variable state
-                // from a specific call to `opt_normalize_projection_type` - if
-                // there's no precise match, the original cache entry is "stranded"
-                // anyway.
-                infcx.resolve_vars_if_possible(predicate.projection_ty),
-            )
-        })
+        Some(ProjectionCacheKey::new(predicate.map_bound(|predicate| {
+            // We don't attempt to match up with a specific type-variable state
+            // from a specific call to `opt_normalize_projection_type` - if
+            // there's no precise match, the original cache entry is "stranded"
+            // anyway.
+            infcx.resolve_vars_if_possible(predicate.projection_ty)
+        })))
     }
 }