Auto merge of #72362 - matthewjasper:remove-rescope, r=nikomatsakis

Remove ReScope

`ReScope` is unnecessary now that AST borrowck is gone and we're erasing the results of region inference in function bodies. This removes about as much of the old regionck code as possible without having to enable NLL fully.

cc #68261

r? @nikomatsakis

2 files changed, 2 insertions, 7 deletions

diff --git a/src/librustc_trait_selection/opaque_types.rs b/src/librustc_trait_selection/opaque_types.rs
index 2544e4ddea2..484677ded24 100644
--- a/src/librustc_trait_selection/opaque_types.rs
+++ b/src/librustc_trait_selection/opaque_types.rs
@@ -670,7 +670,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
 // `least_region`. We cannot use `push_outlives_components` because regions in
 // closure signatures are not included in their outlives components. We need to
 // ensure all regions outlive the given bound so that we don't end up with,
-// say, `ReScope` appearing in a return type and causing ICEs when other
+// say, `ReVar` appearing in a return type and causing ICEs when other
 // functions end up with region constraints involving regions from other
 // functions.
 //
@@ -816,7 +816,7 @@ impl TypeFolder<'tcx> for ReverseMapper<'tcx> {
             // The regions that we expect from borrow checking.
             ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReEmpty(ty::UniverseIndex::ROOT) => {}
 
-            ty::ReEmpty(_) | ty::RePlaceholder(_) | ty::ReVar(_) | ty::ReScope(_) => {
+            ty::ReEmpty(_) | ty::RePlaceholder(_) | ty::ReVar(_) => {
                 // All of the regions in the type should either have been
                 // erased by writeback, or mapped back to named regions by
                 // borrow checking.
@@ -835,7 +835,6 @@ impl TypeFolder<'tcx> for ReverseMapper<'tcx> {
                 if let Some(hidden_ty) = self.hidden_ty.take() {
                     unexpected_hidden_region_diagnostic(
                         self.tcx,
-                        None,
                         self.tcx.def_span(self.opaque_type_def_id),
                         hidden_ty,
                         r,
diff --git a/src/librustc_trait_selection/traits/mod.rs b/src/librustc_trait_selection/traits/mod.rs
index 3daa9109aaf..d8e99dc10af 100644
--- a/src/librustc_trait_selection/traits/mod.rs
+++ b/src/librustc_trait_selection/traits/mod.rs
@@ -28,7 +28,6 @@ use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_errors::ErrorReported;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_middle::middle::region;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::subst::{InternalSubsts, SubstsRef};
 use rustc_middle::ty::{
@@ -237,15 +236,12 @@ fn do_normalize_predicates<'tcx>(
 
         debug!("do_normalize_predictes: normalized predicates = {:?}", predicates);
 
-        let region_scope_tree = region::ScopeTree::default();
-
         // We can use the `elaborated_env` here; the region code only
         // cares about declarations like `'a: 'b`.
         let outlives_env = OutlivesEnvironment::new(elaborated_env);
 
         infcx.resolve_regions_and_report_errors(
             region_context,
-            &region_scope_tree,
             &outlives_env,
             RegionckMode::default(),
         );