Use the existing static and env symbols instead of interning.

Author: nnethercote

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -35,6 +35,7 @@ use rustc_middle::ty::{
     OpaqueHiddenType, OpaqueTypeKey, RegionVid, Ty, TyCtxt, UserType, UserTypeAnnotationIndex,
 };
 use rustc_span::def_id::CRATE_DEF_ID;
+use rustc_span::symbol::sym;
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
 use rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints;
@@ -1347,9 +1348,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                                 BoundRegionInfo::Name(Symbol::intern("anon"))
                             }
                             ty::BoundRegionKind::BrNamed(_, name) => BoundRegionInfo::Name(name),
-                            ty::BoundRegionKind::BrEnv => {
-                                BoundRegionInfo::Name(Symbol::intern("env"))
-                            }
+                            ty::BoundRegionKind::BrEnv => BoundRegionInfo::Name(sym::env),
                         };
 
                         RegionCtxt::LateBound(reg_info)

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -4,6 +4,7 @@ use rustc_infer::traits::PredicateObligations;
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::relate::TypeRelation;
 use rustc_middle::ty::{self, Ty};
+use rustc_span::symbol::sym;
 use rustc_span::{Span, Symbol};
 use rustc_trait_selection::traits::query::Fallible;
 
@@ -127,7 +128,7 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
             ty::BoundRegionKind::BrAnon(Some(span)) => BoundRegionInfo::Span(span),
             ty::BoundRegionKind::BrAnon(..) => BoundRegionInfo::Name(Symbol::intern("anon")),
             ty::BoundRegionKind::BrNamed(_, name) => BoundRegionInfo::Name(name),
-            ty::BoundRegionKind::BrEnv => BoundRegionInfo::Name(Symbol::intern("env")),
+            ty::BoundRegionKind::BrEnv => BoundRegionInfo::Name(sym::env),
         };
 
         let reg_var =

compiler/rustc_borrowck/src/universal_regions.rs

@@ -24,6 +24,7 @@ use rustc_infer::infer::NllRegionVariableOrigin;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::{self, InlineConstSubsts, InlineConstSubstsParts, RegionVid, Ty, TyCtxt};
 use rustc_middle::ty::{InternalSubsts, SubstsRef};
+use rustc_span::symbol::kw;
 use rustc_span::Symbol;
 use std::iter;
 
@@ -404,10 +405,8 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
         assert_eq!(FIRST_GLOBAL_INDEX, self.infcx.num_region_vars());
 
         // Create the "global" region that is always free in all contexts: 'static.
-        let fr_static = self
-            .infcx
-            .next_nll_region_var(FR, || RegionCtxt::Free(Symbol::intern("static")))
-            .to_region_vid();
+        let fr_static =
+            self.infcx.next_nll_region_var(FR, || RegionCtxt::Free(kw::Static)).to_region_vid();
 
         // We've now added all the global regions. The next ones we
         // add will be external.