1 files changed, 17 insertions, 12 deletions

diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs
index e59715b70..ce230afda 100644
--- a/compiler/rustc_infer/src/infer/canonical/mod.rs
+++ b/compiler/rustc_infer/src/infer/canonical/mod.rs
@@ -26,11 +26,11 @@ use crate::infer::{InferCtxt, RegionVariableOrigin, TypeVariableOrigin, TypeVari
 use rustc_index::vec::IndexVec;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::subst::GenericArg;
-use rustc_middle::ty::{self, BoundVar, List};
+use rustc_middle::ty::{self, List, TyCtxt};
 use rustc_span::source_map::Span;
 
 pub use rustc_middle::infer::canonical::*;
-use substitute::CanonicalExt;
+pub use substitute::CanonicalExt;
 
 mod canonicalizer;
 pub mod query_response;
@@ -55,7 +55,7 @@ impl<'tcx> InferCtxt<'tcx> {
         canonical: &Canonical<'tcx, T>,
     ) -> (T, CanonicalVarValues<'tcx>)
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         // For each universe that is referred to in the incoming
         // query, create a universe in our local inference context. In
@@ -87,19 +87,24 @@ impl<'tcx> InferCtxt<'tcx> {
         variables: &List<CanonicalVarInfo<'tcx>>,
         universe_map: impl Fn(ty::UniverseIndex) -> ty::UniverseIndex,
     ) -> CanonicalVarValues<'tcx> {
-        let var_values: IndexVec<BoundVar, GenericArg<'tcx>> = variables
-            .iter()
-            .map(|info| self.instantiate_canonical_var(span, info, &universe_map))
-            .collect();
-
-        CanonicalVarValues { var_values }
+        CanonicalVarValues {
+            var_values: self.tcx.mk_substs_from_iter(
+                variables
+                    .iter()
+                    .map(|info| self.instantiate_canonical_var(span, info, &universe_map)),
+            ),
+        }
     }
 
     /// Given the "info" about a canonical variable, creates a fresh
     /// variable for it. If this is an existentially quantified
     /// variable, then you'll get a new inference variable; if it is a
     /// universally quantified variable, you get a placeholder.
-    fn instantiate_canonical_var(
+    ///
+    /// FIXME(-Ztrait-solver=next): This is public because it's used by the
+    /// new trait solver which has a different canonicalization routine.
+    /// We should somehow deduplicate all of this.
+    pub fn instantiate_canonical_var(
         &self,
         span: Span,
         cv_info: CanonicalVarInfo<'tcx>,
@@ -123,7 +128,7 @@ impl<'tcx> InferCtxt<'tcx> {
             CanonicalVarKind::PlaceholderTy(ty::PlaceholderType { universe, name }) => {
                 let universe_mapped = universe_map(universe);
                 let placeholder_mapped = ty::PlaceholderType { universe: universe_mapped, name };
-                self.tcx.mk_ty(ty::Placeholder(placeholder_mapped)).into()
+                self.tcx.mk_placeholder(placeholder_mapped).into()
             }
 
             CanonicalVarKind::Region(ui) => self
@@ -136,7 +141,7 @@ impl<'tcx> InferCtxt<'tcx> {
             CanonicalVarKind::PlaceholderRegion(ty::PlaceholderRegion { universe, name }) => {
                 let universe_mapped = universe_map(universe);
                 let placeholder_mapped = ty::PlaceholderRegion { universe: universe_mapped, name };
-                self.tcx.mk_region(ty::RePlaceholder(placeholder_mapped)).into()
+                self.tcx.mk_re_placeholder(placeholder_mapped).into()
             }
 
             CanonicalVarKind::Const(ui, ty) => self