1 files changed, 7 insertions, 25 deletions

diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index 2a7713bc4..2beb5e0ab 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -22,8 +22,8 @@ use rustc_hir::{BodyOwnerKind, HirId};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
 use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use rustc_middle::ty::{self, InlineConstSubsts, InlineConstSubstsParts, RegionVid, Ty, TyCtxt};
+use rustc_middle::ty::{InternalSubsts, SubstsRef};
 use std::iter;
 
 use crate::nll::ToRegionVid;
@@ -54,13 +54,6 @@ pub struct UniversalRegions<'tcx> {
     /// The total number of universal region variables instantiated.
     num_universals: usize,
 
-    /// A special region variable created for the `'empty(U0)` region.
-    /// Note that this is **not** a "universal" region, as it doesn't
-    /// represent a universally bound placeholder or any such thing.
-    /// But we do create it here in this type because it's a useful region
-    /// to have around in a few limited cases.
-    pub root_empty: RegionVid,
-
     /// The "defining" type for this function, with all universal
     /// regions instantiated. For a closure or generator, this is the
     /// closure type, but for a top-level function it's the `FnDef`.
@@ -226,7 +219,7 @@ impl<'tcx> UniversalRegions<'tcx> {
     /// signature. This will also compute the relationships that are
     /// known between those regions.
     pub fn new(
-        infcx: &InferCtxt<'_, 'tcx>,
+        infcx: &InferCtxt<'tcx>,
         mir_def: ty::WithOptConstParam<LocalDefId>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> Self {
@@ -323,11 +316,7 @@ impl<'tcx> UniversalRegions<'tcx> {
 
     /// See `UniversalRegionIndices::to_region_vid`.
     pub fn to_region_vid(&self, r: ty::Region<'tcx>) -> RegionVid {
-        if let ty::ReEmpty(ty::UniverseIndex::ROOT) = *r {
-            self.root_empty
-        } else {
-            self.indices.to_region_vid(r)
-        }
+        self.indices.to_region_vid(r)
     }
 
     /// As part of the NLL unit tests, you can annotate a function with
@@ -393,7 +382,7 @@ impl<'tcx> UniversalRegions<'tcx> {
 }
 
 struct UniversalRegionsBuilder<'cx, 'tcx> {
-    infcx: &'cx InferCtxt<'cx, 'tcx>,
+    infcx: &'cx InferCtxt<'tcx>,
     mir_def: ty::WithOptConstParam<LocalDefId>,
     mir_hir_id: HirId,
     param_env: ty::ParamEnv<'tcx>,
@@ -425,7 +414,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
 
         let typeck_root_def_id = self.infcx.tcx.typeck_root_def_id(self.mir_def.did.to_def_id());
 
-        // If this is is a 'root' body (not a closure/generator/inline const), then
+        // If this is a 'root' body (not a closure/generator/inline const), then
         // there are no extern regions, so the local regions start at the same
         // position as the (empty) sub-list of extern regions
         let first_local_index = if self.mir_def.did.to_def_id() == typeck_root_def_id {
@@ -501,16 +490,10 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
             _ => None,
         };
 
-        let root_empty = self
-            .infcx
-            .next_nll_region_var(NllRegionVariableOrigin::Existential { from_forall: true })
-            .to_region_vid();
-
         UniversalRegions {
             indices,
             fr_static,
             fr_fn_body,
-            root_empty,
             first_extern_index,
             first_local_index,
             num_universals,
@@ -716,7 +699,7 @@ trait InferCtxtExt<'tcx> {
     );
 }
 
-impl<'cx, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'cx, 'tcx> {
+impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
     fn replace_free_regions_with_nll_infer_vars<T>(
         &self,
         origin: NllRegionVariableOrigin,
@@ -768,10 +751,9 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'cx, 'tcx> {
         mir_def_id: LocalDefId,
         indices: &mut UniversalRegionIndices<'tcx>,
     ) {
-        debug!("replace_late_bound_regions_with_nll_infer_vars(mir_def_id={:?})", mir_def_id);
         let typeck_root_def_id = self.tcx.typeck_root_def_id(mir_def_id.to_def_id());
         for_each_late_bound_region_defined_on(self.tcx, typeck_root_def_id, |r| {
-            debug!("replace_late_bound_regions_with_nll_infer_vars: r={:?}", r);
+            debug!(?r);
             if !indices.indices.contains_key(&r) {
                 let region_vid = self.next_nll_region_var(FR);
                 debug!(?region_vid);