store the CodeExtent directly in FreeRegion

this makes the code cleaner

src/librustc/metadata/tydecode.rs

@@ -225,7 +225,7 @@ impl<'a,'tcx> TyDecoder<'a,'tcx> {
             }
             'f' => {
                 assert_eq!(self.next(), '[');
-                let scope = self.parse_destruction_scope_data();
+                let scope = self.parse_scope();
                 assert_eq!(self.next(), '|');
                 let br = self.parse_bound_region();
                 assert_eq!(self.next(), ']');
@@ -284,11 +284,6 @@ impl<'a,'tcx> TyDecoder<'a,'tcx> {
         })
     }
 
-    fn parse_destruction_scope_data(&mut self) -> region::DestructionScopeData {
-        let node_id = self.parse_uint() as ast::NodeId;
-        region::DestructionScopeData::new(node_id)
-    }
-
     fn parse_opt<T, F>(&mut self, f: F) -> Option<T>
         where F: FnOnce(&mut TyDecoder<'a, 'tcx>) -> T,
     {

src/librustc/metadata/tyencode.rs

@@ -255,7 +255,7 @@ pub fn enc_region(w: &mut Encoder, cx: &ctxt, r: ty::Region) {
         }
         ty::ReFree(ref fr) => {
             mywrite!(w, "f[");
-            enc_destruction_scope_data(w, fr.scope);
+            enc_scope(w, cx, fr.scope);
             mywrite!(w, "|");
             enc_bound_region(w, cx, fr.bound_region);
             mywrite!(w, "]");
@@ -289,11 +289,6 @@ fn enc_scope(w: &mut Encoder, cx: &ctxt, scope: region::CodeExtent) {
     }
 }
 
-fn enc_destruction_scope_data(w: &mut Encoder,
-                              d: region::DestructionScopeData) {
-    mywrite!(w, "{}", d.node_id);
-}
-
 fn enc_bound_region(w: &mut Encoder, cx: &ctxt, br: ty::BoundRegion) {
     match br {
         ty::BrAnon(idx) => {

src/librustc/middle/free_region.rs

@@ -135,8 +135,7 @@ impl FreeRegionMap {
                     tcx.region_maps.is_subscope_of(sub_scope, super_scope),
 
                 (ty::ReScope(sub_scope), ty::ReFree(fr)) =>
-                    tcx.region_maps.is_subscope_of(sub_scope,
-                                                   fr.scope.to_code_extent(&tcx.region_maps)) ||
+                    tcx.region_maps.is_subscope_of(sub_scope, fr.scope) ||
                     self.is_static(fr),
 
                 (ty::ReFree(sub_fr), ty::ReFree(super_fr)) =>

src/librustc/middle/infer/error_reporting.rs

@@ -172,7 +172,7 @@ impl<'tcx> ty::ctxt<'tcx> {
                     }
                 };
 
-                match self.map.find(fr.scope.node_id) {
+                match self.map.find(fr.scope.node_id(&self.region_maps)) {
                     Some(ast_map::NodeBlock(ref blk)) => {
                         let (msg, opt_span) = explain_span(self, "block", blk.span);
                         (format!("{} {}", prefix, msg), opt_span)
@@ -183,7 +183,8 @@ impl<'tcx> ty::ctxt<'tcx> {
                         (format!("{} {}", prefix, msg), opt_span)
                     }
                     Some(_) | None => {
-                        // this really should not happen
+                        // this really should not happen, but it does:
+                        // FIXME(#27942)
                         (format!("{} unknown free region bounded by scope {:?}",
                                  prefix, fr.scope), None)
                     }
@@ -422,7 +423,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
                         return None
                     }
                     assert!(fr1.scope == fr2.scope);
-                    (fr1.scope.node_id, fr1, fr2)
+                    (fr1.scope.node_id(&tcx.region_maps), fr1, fr2)
                 },
                 _ => return None
             };

src/librustc/middle/infer/region_inference/mod.rs

@@ -790,10 +790,9 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
             // A "free" region can be interpreted as "some region
             // at least as big as the block fr.scope_id".  So, we can
             // reasonably compare free regions and scopes:
-            let fr_scope = fr.scope.to_code_extent(&self.tcx.region_maps);
-            let r_id = self.tcx.region_maps.nearest_common_ancestor(fr_scope, s_id);
+            let r_id = self.tcx.region_maps.nearest_common_ancestor(fr.scope, s_id);
 
-            if r_id == fr_scope {
+            if r_id == fr.scope {
               // if the free region's scope `fr.scope_id` is bigger than
               // the scope region `s_id`, then the LUB is the free
               // region itself:
@@ -871,8 +870,7 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
                 // than the scope `s_id`, then we can say that the GLB
                 // is the scope `s_id`.  Otherwise, as we do not know
                 // big the free region is precisely, the GLB is undefined.
-                let fr_scope = fr.scope.to_code_extent(&self.tcx.region_maps);
-                if self.tcx.region_maps.nearest_common_ancestor(fr_scope, s_id) == fr_scope ||
+                if self.tcx.region_maps.nearest_common_ancestor(fr.scope, s_id) == fr.scope ||
                         free_regions.is_static(fr) {
                     Ok(s)
                 } else {
@@ -927,8 +925,7 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
                 Ok(ty::ReFree(*b))
             } else {
                 this.intersect_scopes(ty::ReFree(*a), ty::ReFree(*b),
-                                      a.scope.to_code_extent(&this.tcx.region_maps),
-                                      b.scope.to_code_extent(&this.tcx.region_maps))
+                                      a.scope, b.scope)
             }
         }
     }

src/librustc/middle/liveness.rs

@@ -111,7 +111,6 @@ use self::VarKind::*;
 
 use middle::def::*;
 use middle::pat_util;
-use middle::region;
 use middle::ty;
 use lint;
 use util::nodemap::NodeMap;
@@ -1509,7 +1508,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
         // within the fn body, late-bound regions are liberated:
         let fn_ret =
             self.ir.tcx.liberate_late_bound_regions(
-                region::DestructionScopeData::new(body.id),
+                self.ir.tcx.region_maps.item_extent(body.id),
                 &self.fn_ret(id));
 
         match fn_ret {

src/librustc/middle/mem_categorization.rs

@@ -77,7 +77,6 @@ use middle::def_id::DefId;
 use middle::infer;
 use middle::check_const;
 use middle::def;
-use middle::region;
 use middle::ty::{self, Ty};
 
 use syntax::ast::{MutImmutable, MutMutable};
@@ -749,7 +748,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
             // The environment of a closure is guaranteed to
             // outlive any bindings introduced in the body of the
             // closure itself.
-            scope: region::DestructionScopeData::new(fn_body_id),
+            scope: self.tcx().region_maps.item_extent(fn_body_id),
             bound_region: ty::BrEnv
         });
 

src/librustc/middle/region.rs

@@ -309,6 +309,13 @@ impl RegionMaps {
     pub fn lookup_code_extent(&self, e: CodeExtentData) -> CodeExtent {
         self.code_extent_interner.borrow()[&e]
     }
+    pub fn node_extent(&self, n: ast::NodeId) -> CodeExtent {
+        self.lookup_code_extent(CodeExtentData::Misc(n))
+    }
+    // Returns the code extent for an item - the destruction scope.
+    pub fn item_extent(&self, n: ast::NodeId) -> CodeExtent {
+        self.lookup_code_extent(CodeExtentData::DestructionScope(n))
+    }
     pub fn intern_code_extent(&self,
                               e: CodeExtentData,
                               parent: CodeExtent) -> CodeExtent {
@@ -350,9 +357,6 @@ impl RegionMaps {
                        parent: CodeExtent) -> CodeExtent {
         self.intern_code_extent(CodeExtentData::Misc(n), parent)
     }
-    pub fn node_extent(&self, n: ast::NodeId) -> CodeExtent {
-        self.lookup_code_extent(CodeExtentData::Misc(n))
-    }
     pub fn code_extent_data(&self, e: CodeExtent) -> CodeExtentData {
         self.code_extents.borrow()[e.0 as usize]
     }

src/librustc/middle/ty.rs

@@ -1679,7 +1679,7 @@ impl Region {
 /// A "free" region `fr` can be interpreted as "some region
 /// at least as big as the scope `fr.scope`".
 pub struct FreeRegion {
-    pub scope: region::DestructionScopeData,
+    pub scope: region::CodeExtent,
     pub bound_region: BoundRegion
 }
 
@@ -6610,7 +6610,7 @@ impl<'tcx> ctxt<'tcx> {
             types.push(def.space, self.mk_param_from_def(def));
         }
 
-        let free_id_outlive = region::DestructionScopeData::new(free_id);
+        let free_id_outlive = self.region_maps.item_extent(free_id);
 
         // map bound 'a => free 'a
         let mut regions = VecPerParamSpace::empty();
@@ -6641,7 +6641,7 @@ impl<'tcx> ctxt<'tcx> {
         //
 
         let free_substs = self.construct_free_substs(generics, free_id);
-        let free_id_outlive = region::DestructionScopeData::new(free_id);
+        let free_id_outlive = self.region_maps.item_extent(free_id);
 
         //
         // Compute the bounds on Self and the type parameters.
@@ -6673,8 +6673,7 @@ impl<'tcx> ctxt<'tcx> {
         let unnormalized_env = ty::ParameterEnvironment {
             tcx: self,
             free_substs: free_substs,
-            implicit_region_bound: ty::ReScope(
-                free_id_outlive.to_code_extent(&self.region_maps)),
+            implicit_region_bound: ty::ReScope(free_id_outlive),
             caller_bounds: predicates,
             selection_cache: traits::SelectionCache::new(),
             free_id: free_id,
@@ -6838,7 +6837,7 @@ impl<'tcx> ctxt<'tcx> {
     /// Replace any late-bound regions bound in `value` with free variants attached to scope-id
     /// `scope_id`.
     pub fn liberate_late_bound_regions<T>(&self,
-        all_outlive_scope: region::DestructionScopeData,
+        all_outlive_scope: region::CodeExtent,
         value: &Binder<T>)
         -> T
         where T : TypeFoldable<'tcx>

src/librustc_borrowck/borrowck/gather_loans/mod.rs

@@ -360,9 +360,7 @@ impl<'a, 'tcx> GatherLoanCtxt<'a, 'tcx> {
                 let loan_scope = match loan_region {
                     ty::ReScope(scope) => scope,
 
-                    ty::ReFree(ref fr) => {
-                        fr.scope.to_code_extent(&self.tcx().region_maps)
-                    }
+                    ty::ReFree(ref fr) => fr.scope,
 
                     ty::ReStatic => {
                         // If we get here, an error must have been

src/librustc_typeck/astconv.rs

@@ -179,7 +179,7 @@ pub fn ast_region_to_region(tcx: &ty::ctxt, lifetime: &ast::Lifetime)
 
         Some(&rl::DefFreeRegion(scope, id)) => {
             ty::ReFree(ty::FreeRegion {
-                    scope: scope,
+                    scope: tcx.region_maps.item_extent(scope.node_id),
                     bound_region: ty::BrNamed(DefId::local(id),
                                               lifetime.name)
                 })

src/librustc_typeck/check/closure.rs

@@ -14,7 +14,6 @@ use super::{check_fn, Expectation, FnCtxt};
 
 use astconv;
 use middle::def_id::DefId;
-use middle::region;
 use middle::subst;
 use middle::ty::{self, ToPolyTraitRef, Ty};
 use std::cmp;
@@ -77,7 +76,7 @@ fn check_closure<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
     fcx.write_ty(expr.id, closure_type);
 
     let fn_sig = fcx.tcx().liberate_late_bound_regions(
-        region::DestructionScopeData::new(body.id), &fn_ty.sig);
+        fcx.tcx().region_maps.item_extent(body.id), &fn_ty.sig);
 
     check_fn(fcx.ccx,
              ast::Unsafety::Normal,

src/librustc_typeck/check/mod.rs

@@ -91,7 +91,6 @@ use middle::infer;
 use middle::infer::type_variable;
 use middle::pat_util::{self, pat_id_map};
 use middle::privacy::{AllPublic, LastMod};
-use middle::region::{self};
 use middle::subst::{self, Subst, Substs, VecPerParamSpace, ParamSpace, TypeSpace};
 use middle::traits::{self, report_fulfillment_errors};
 use middle::ty::{FnSig, GenericPredicates, TypeScheme};
@@ -455,11 +454,11 @@ fn check_bare_fn<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
             let inh = Inherited::new(ccx.tcx, &tables, param_env);
 
             // Compute the fty from point of view of inside fn.
+            let fn_scope = ccx.tcx.region_maps.item_extent(body.id);
             let fn_sig =
                 fn_ty.sig.subst(ccx.tcx, &inh.infcx.parameter_environment.free_substs);
             let fn_sig =
-                ccx.tcx.liberate_late_bound_regions(region::DestructionScopeData::new(body.id),
-                                                    &fn_sig);
+                ccx.tcx.liberate_late_bound_regions(fn_scope, &fn_sig);
             let fn_sig =
                 inh.normalize_associated_types_in(body.span,
                                                   body.id,

src/librustc_typeck/check/wf.rs

@@ -466,10 +466,7 @@ pub struct BoundsChecker<'cx,'tcx:'cx> {
     fcx: &'cx FnCtxt<'cx,'tcx>,
     span: Span,
 
-    // This field is often attached to item impls; it is not clear
-    // that `CodeExtent` is well-defined for such nodes, so pnkfelix
-    // has left it as a NodeId rather than porting to CodeExtent.
-    scope: ast::NodeId,
+    scope: region::CodeExtent,
 
     binding_count: usize,
     cache: Option<&'cx mut HashSet<Ty<'tcx>>>,
@@ -480,6 +477,7 @@ impl<'cx,'tcx> BoundsChecker<'cx,'tcx> {
                scope: ast::NodeId,
                cache: Option<&'cx mut HashSet<Ty<'tcx>>>)
                -> BoundsChecker<'cx,'tcx> {
+        let scope = fcx.tcx().region_maps.item_extent(scope);
         BoundsChecker { fcx: fcx, span: DUMMY_SP, scope: scope,
                         cache: cache, binding_count: 0 }
     }
@@ -532,7 +530,7 @@ impl<'cx,'tcx> TypeFolder<'tcx> for BoundsChecker<'cx,'tcx> {
     {
         self.binding_count += 1;
         let value = self.fcx.tcx().liberate_late_bound_regions(
-            region::DestructionScopeData::new(self.scope),
+            self.scope,
             binder);
         debug!("BoundsChecker::fold_binder: late-bound regions replaced: {:?} at scope: {:?}",
                value, self.scope);

src/librustc_typeck/check/wfcheck.rs

@@ -13,7 +13,6 @@ use check::{FnCtxt, Inherited, blank_fn_ctxt, regionck};
 use constrained_type_params::{identify_constrained_type_params, Parameter};
 use CrateCtxt;
 use middle::def_id::DefId;
-use middle::region::DestructionScopeData;
 use middle::subst::{self, TypeSpace, FnSpace, ParamSpace, SelfSpace};
 use middle::traits;
 use middle::ty::{self, Ty};
@@ -362,7 +361,7 @@ impl<'ccx, 'tcx> CheckTypeWellFormedVisitor<'ccx, 'tcx> {
     {
         let free_substs = &fcx.inh.infcx.parameter_environment.free_substs;
         let fty = fcx.instantiate_type_scheme(span, free_substs, fty);
-        let free_id_outlive = DestructionScopeData::new(free_id);
+        let free_id_outlive = fcx.tcx().region_maps.item_extent(free_id);
         let sig = fcx.tcx().liberate_late_bound_regions(free_id_outlive, &fty.sig);
 
         for &input_ty in &sig.inputs {

src/librustc_typeck/collect.rs

@@ -2311,7 +2311,7 @@ fn check_method_self_type<'a, 'tcx, RS:RegionScope>(
             _ => typ,
         };
 
-        let body_scope = region::DestructionScopeData::new(body_id);
+        let body_scope = tcx.region_maps.item_extent(body_id);
 
         // "Required type" comes from the trait definition. It may
         // contain late-bound regions from the method, but not the
@@ -2363,7 +2363,7 @@ fn check_method_self_type<'a, 'tcx, RS:RegionScope>(
 
     fn liberate_early_bound_regions<'tcx,T>(
         tcx: &ty::ctxt<'tcx>,
-        scope: region::DestructionScopeData,
+        scope: region::CodeExtent,
         value: &T)
         -> T
         where T : TypeFoldable<'tcx>