Rollup merge of #110175 - nnethercote:symbol-cleanups, r=jackh726

Symbol cleanups

r? ```@jackh726```

cc ```@b-naber```

compiler/rustc_borrowck/src/renumber.rs

@@ -69,12 +69,10 @@ impl RegionCtxt {
     /// Used to determine the representative of a component in the strongly connected
     /// constraint graph
     pub(crate) fn preference_value(self) -> usize {
-        let _anon = Symbol::intern("anon");
-
         match self {
             RegionCtxt::Unknown => 1,
             RegionCtxt::Existential(None) => 2,
-            RegionCtxt::Existential(Some(_anon)) | RegionCtxt::Free(_anon) => 2,
+            RegionCtxt::Existential(Some(_)) | RegionCtxt::Free(_) => 2,
             RegionCtxt::Location(_) => 3,
             RegionCtxt::TyContext(_) => 4,
             _ => 5,

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;
@@ -1338,18 +1339,13 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 };
                 let (sig, map) = tcx.replace_late_bound_regions(sig, |br| {
                     use crate::renumber::{BoundRegionInfo, RegionCtxt};
-                    use rustc_span::Symbol;
 
                     let region_ctxt_fn = || {
                         let reg_info = match br.kind {
                             ty::BoundRegionKind::BrAnon(Some(span)) => BoundRegionInfo::Span(span),
-                            ty::BoundRegionKind::BrAnon(..) => {
+                            ty::BoundRegionKind::BrAnon(..) => BoundRegionInfo::Name(sym::anon),
-                                BoundRegionInfo::Name(Symbol::intern("anon"))
-                            }
                             ty::BoundRegionKind::BrNamed(_, name) => BoundRegionInfo::Name(name),
-                            ty::BoundRegionKind::BrEnv => {
+                            ty::BoundRegionKind::BrEnv => BoundRegionInfo::Name(sym::env),
-                                BoundRegionInfo::Name(Symbol::intern("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;
 
@@ -125,9 +126,9 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
 
         let reg_info = match placeholder.bound.kind {
             ty::BoundRegionKind::BrAnon(Some(span)) => BoundRegionInfo::Span(span),
-            ty::BoundRegionKind::BrAnon(..) => BoundRegionInfo::Name(Symbol::intern("anon")),
+            ty::BoundRegionKind::BrAnon(..) => BoundRegionInfo::Name(sym::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, sym};
 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
+        let fr_static =
-            .infcx
+            self.infcx.next_nll_region_var(FR, || RegionCtxt::Free(kw::Static)).to_region_vid();
-            .next_nll_region_var(FR, || RegionCtxt::Free(Symbol::intern("static")))
-            .to_region_vid();
 
         // We've now added all the global regions. The next ones we
         // add will be external.
@@ -440,11 +439,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                     debug!(?r);
                     if !indices.indices.contains_key(&r) {
                         let region_vid = {
-                            let name = match r.get_name() {
+                            let name = r.get_name_or_anon();
-                                Some(name) => name,
-                                _ => Symbol::intern("anon"),
-                            };
-
                             self.infcx.next_nll_region_var(FR, || {
                                 RegionCtxt::LateBound(BoundRegionInfo::Name(name))
                             })
@@ -478,11 +473,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
             debug!(?r);
             if !indices.indices.contains_key(&r) {
                 let region_vid = {
-                    let name = match r.get_name() {
+                    let name = r.get_name_or_anon();
-                        Some(name) => name,
-                        _ => Symbol::intern("anon"),
-                    };
-
                     self.infcx.next_nll_region_var(FR, || {
                         RegionCtxt::LateBound(BoundRegionInfo::Name(name))
                     })
@@ -768,15 +759,10 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for BorrowckInferCtxt<'cx, 'tcx> {
         T: TypeFoldable<TyCtxt<'tcx>>,
     {
         self.infcx.tcx.fold_regions(value, |region, _depth| {
-            let name = match region.get_name() {
+            let name = region.get_name_or_anon();
-                Some(name) => name,
-                _ => Symbol::intern("anon"),
-            };
             debug!(?region, ?name);
 
-            let reg_var = self.next_nll_region_var(origin, || RegionCtxt::Free(name));
+            self.next_nll_region_var(origin, || RegionCtxt::Free(name))
-
-            reg_var
         })
     }
 
@@ -797,7 +783,7 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for BorrowckInferCtxt<'cx, 'tcx> {
             let region_vid = {
                 let name = match br.kind.get_name() {
                     Some(name) => name,
-                    _ => Symbol::intern("anon"),
+                    _ => sym::anon,
                 };
 
                 self.next_nll_region_var(origin, || RegionCtxt::Bound(BoundRegionInfo::Name(name)))
@@ -829,11 +815,7 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for BorrowckInferCtxt<'cx, 'tcx> {
             debug!(?r);
             if !indices.indices.contains_key(&r) {
                 let region_vid = {
-                    let name = match r.get_name() {
+                    let name = r.get_name_or_anon();
-                        Some(name) => name,
-                        _ => Symbol::intern("anon"),
-                    };
-
                     self.next_nll_region_var(FR, || {
                         RegionCtxt::LateBound(BoundRegionInfo::Name(name))
                     })
@@ -855,11 +837,7 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for BorrowckInferCtxt<'cx, 'tcx> {
             debug!(?r);
             if !indices.indices.contains_key(&r) {
                 let region_vid = {
-                    let name = match r.get_name() {
+                    let name = r.get_name_or_anon();
-                        Some(name) => name,
-                        _ => Symbol::intern("anon"),
-                    };
-
                     self.next_nll_region_var(FR, || {
                         RegionCtxt::LateBound(BoundRegionInfo::Name(name))
                     })

compiler/rustc_middle/src/ty/sty.rs

@@ -1621,19 +1621,24 @@ impl<'tcx> Region<'tcx> {
 
     pub fn get_name(self) -> Option<Symbol> {
         if self.has_name() {
-            let name = match *self {
+            match *self {
                 ty::ReEarlyBound(ebr) => Some(ebr.name),
                 ty::ReLateBound(_, br) => br.kind.get_name(),
                 ty::ReFree(fr) => fr.bound_region.get_name(),
                 ty::ReStatic => Some(kw::StaticLifetime),
                 ty::RePlaceholder(placeholder) => placeholder.bound.kind.get_name(),
                 _ => None,
-            };
+            }
-
+        } else {
-            return name;
+            None
         }
+    }
 
-        None
+    pub fn get_name_or_anon(self) -> Symbol {
+        match self.get_name() {
+            Some(name) => name,
+            None => sym::anon,
+        }
     }
 
     /// Is this region named by the user?

compiler/rustc_span/src/symbol.rs

@@ -357,6 +357,7 @@ symbols! {
         always,
         and,
         and_then,
+        anon,
         anonymous_lifetime_in_impl_trait,
         any,
         append_const_msg,