1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Name resolution for lifetimes.
13 //! Name resolution for lifetimes follows MUCH simpler rules than the
14 //! full resolve. For example, lifetime names are never exported or
15 //! used between functions, and they operate in a purely top-down
16 //! way. Therefore we break lifetime name resolution into a separate pass.
18 pub use self::DefRegion::*;
19 use self::ScopeChain::*;
22 use middle::def::{self, DefMap};
27 use std::mem::replace;
29 use syntax::codemap::Span;
30 use syntax::parse::token::special_idents;
31 use util::nodemap::NodeMap;
34 use rustc_front::print::pprust::lifetime_to_string;
35 use rustc_front::intravisit::{self, Visitor, FnKind};
37 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug)]
40 DefEarlyBoundRegion(/* space */ subst::ParamSpace,
42 /* lifetime decl */ ast::NodeId),
43 DefLateBoundRegion(ty::DebruijnIndex,
44 /* lifetime decl */ ast::NodeId),
45 DefFreeRegion(/* block scope */ region::DestructionScopeData,
46 /* lifetime decl */ ast::NodeId),
49 // Maps the id of each lifetime reference to the lifetime decl
50 // that it corresponds to.
51 pub type NamedRegionMap = NodeMap<DefRegion>;
53 struct LifetimeContext<'a> {
55 named_region_map: &'a mut NamedRegionMap,
58 // Deep breath. Our representation for poly trait refs contains a single
59 // binder and thus we only allow a single level of quantification. However,
60 // the syntax of Rust permits quantification in two places, e.g., `T: for <'a> Foo<'a>`
61 // and `for <'a, 'b> &'b T: Foo<'a>`. In order to get the de Bruijn indices
62 // correct when representing these constraints, we should only introduce one
63 // scope. However, we want to support both locations for the quantifier and
64 // during lifetime resolution we want precise information (so we can't
65 // desugar in an earlier phase).
67 // SO, if we encounter a quantifier at the outer scope, we set
68 // trait_ref_hack to true (and introduce a scope), and then if we encounter
69 // a quantifier at the inner scope, we error. If trait_ref_hack is false,
70 // then we introduce the scope at the inner quantifier.
75 // List of labels in the function/method currently under analysis.
76 labels_in_fn: Vec<(ast::Name, Span)>,
80 /// EarlyScope(i, ['a, 'b, ...], s) extends s with early-bound
81 /// lifetimes, assigning indexes 'a => i, 'b => i+1, ... etc.
82 EarlyScope(subst::ParamSpace, &'a Vec<hir::LifetimeDef>, Scope<'a>),
83 /// LateScope(['a, 'b, ...], s) extends s with late-bound
84 /// lifetimes introduced by the declaration binder_id.
85 LateScope(&'a Vec<hir::LifetimeDef>, Scope<'a>),
86 /// lifetimes introduced by items within a code block are scoped
88 BlockScope(region::DestructionScopeData, Scope<'a>),
92 type Scope<'a> = &'a ScopeChain<'a>;
94 static ROOT_SCOPE: ScopeChain<'static> = RootScope;
96 pub fn krate(sess: &Session, krate: &hir::Crate, def_map: &DefMap) -> NamedRegionMap {
97 let mut named_region_map = NodeMap();
98 krate.visit_all_items(&mut LifetimeContext {
100 named_region_map: &mut named_region_map,
103 trait_ref_hack: false,
104 labels_in_fn: vec![],
106 sess.abort_if_errors();
110 impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
111 fn visit_item(&mut self, item: &hir::Item) {
112 assert!(self.labels_in_fn.is_empty());
114 // Items always introduce a new root scope
115 self.with(RootScope, |_, this| {
118 // Fn lifetimes get added in visit_fn below:
119 intravisit::walk_item(this, item);
121 hir::ItemExternCrate(_) |
124 hir::ItemDefaultImpl(..) |
125 hir::ItemForeignMod(..) |
126 hir::ItemStatic(..) |
127 hir::ItemConst(..) => {
128 // These sorts of items have no lifetime parameters at all.
129 intravisit::walk_item(this, item);
131 hir::ItemTy(_, ref generics) |
132 hir::ItemEnum(_, ref generics) |
133 hir::ItemStruct(_, ref generics) |
134 hir::ItemTrait(_, ref generics, _, _) |
135 hir::ItemImpl(_, _, ref generics, _, _, _) => {
136 // These kinds of items have only early bound lifetime parameters.
137 let lifetimes = &generics.lifetimes;
138 let early_scope = EarlyScope(subst::TypeSpace, lifetimes, &ROOT_SCOPE);
139 this.with(early_scope, |old_scope, this| {
140 this.check_lifetime_defs(old_scope, lifetimes);
141 intravisit::walk_item(this, item);
147 // Done traversing the item; remove any labels it created
148 self.labels_in_fn.truncate(0);
151 fn visit_foreign_item(&mut self, item: &hir::ForeignItem) {
152 // Items save/restore the set of labels. This way inner items
153 // can freely reuse names, be they loop labels or lifetimes.
154 let saved = replace(&mut self.labels_in_fn, vec![]);
156 // Items always introduce a new root scope
157 self.with(RootScope, |_, this| {
159 hir::ForeignItemFn(_, ref generics) => {
160 this.visit_early_late(subst::FnSpace, generics, |this| {
161 intravisit::walk_foreign_item(this, item);
164 hir::ForeignItemStatic(..) => {
165 intravisit::walk_foreign_item(this, item);
170 // Done traversing the item; restore saved set of labels.
171 replace(&mut self.labels_in_fn, saved);
174 fn visit_fn(&mut self, fk: FnKind<'v>, fd: &'v hir::FnDecl,
175 b: &'v hir::Block, s: Span, _: ast::NodeId) {
177 FnKind::ItemFn(_, generics, _, _, _, _) => {
178 self.visit_early_late(subst::FnSpace, generics, |this| {
179 this.walk_fn(fk, fd, b, s)
182 FnKind::Method(_, sig, _) => {
183 self.visit_early_late(subst::FnSpace, &sig.generics, |this| {
184 this.walk_fn(fk, fd, b, s)
187 FnKind::Closure(..) => {
188 self.walk_fn(fk, fd, b, s)
193 fn visit_ty(&mut self, ty: &hir::Ty) {
195 hir::TyBareFn(ref c) => {
196 self.with(LateScope(&c.lifetimes, self.scope), |old_scope, this| {
197 // a bare fn has no bounds, so everything
198 // contained within is scoped within its binder.
199 this.check_lifetime_defs(old_scope, &c.lifetimes);
200 intravisit::walk_ty(this, ty);
203 hir::TyPath(None, ref path) => {
204 // if this path references a trait, then this will resolve to
205 // a trait ref, which introduces a binding scope.
206 match self.def_map.get(&ty.id).map(|d| (d.base_def, d.depth)) {
207 Some((def::DefTrait(..), 0)) => {
208 self.with(LateScope(&Vec::new(), self.scope), |_, this| {
209 this.visit_path(path, ty.id);
213 intravisit::walk_ty(self, ty);
218 intravisit::walk_ty(self, ty)
223 fn visit_trait_item(&mut self, trait_item: &hir::TraitItem) {
224 // We reset the labels on every trait item, so that different
225 // methods in an impl can reuse label names.
226 let saved = replace(&mut self.labels_in_fn, vec![]);
228 if let hir::MethodTraitItem(ref sig, None) = trait_item.node {
229 self.visit_early_late(
230 subst::FnSpace, &sig.generics,
231 |this| intravisit::walk_trait_item(this, trait_item))
233 intravisit::walk_trait_item(self, trait_item);
236 replace(&mut self.labels_in_fn, saved);
239 fn visit_block(&mut self, b: &hir::Block) {
240 self.with(BlockScope(region::DestructionScopeData::new(b.id),
242 |_, this| intravisit::walk_block(this, b));
245 fn visit_lifetime(&mut self, lifetime_ref: &hir::Lifetime) {
246 if lifetime_ref.name == special_idents::static_lifetime.name {
247 self.insert_lifetime(lifetime_ref, DefStaticRegion);
250 self.resolve_lifetime_ref(lifetime_ref);
253 fn visit_generics(&mut self, generics: &hir::Generics) {
254 for ty_param in generics.ty_params.iter() {
255 walk_list!(self, visit_ty_param_bound, &ty_param.bounds);
256 match ty_param.default {
257 Some(ref ty) => self.visit_ty(&**ty),
261 for predicate in &generics.where_clause.predicates {
263 &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate{ ref bounded_ty,
267 if !bound_lifetimes.is_empty() {
268 self.trait_ref_hack = true;
269 let result = self.with(LateScope(bound_lifetimes, self.scope),
271 this.check_lifetime_defs(old_scope, bound_lifetimes);
272 this.visit_ty(&**bounded_ty);
273 walk_list!(this, visit_ty_param_bound, bounds);
275 self.trait_ref_hack = false;
278 self.visit_ty(&**bounded_ty);
279 walk_list!(self, visit_ty_param_bound, bounds);
282 &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate{ref lifetime,
286 self.visit_lifetime(lifetime);
287 for bound in bounds {
288 self.visit_lifetime(bound);
291 &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate{ id,
295 self.visit_path(path, id);
296 self.visit_ty(&**ty);
302 fn visit_poly_trait_ref(&mut self,
303 trait_ref: &hir::PolyTraitRef,
304 _modifier: &hir::TraitBoundModifier) {
305 debug!("visit_poly_trait_ref trait_ref={:?}", trait_ref);
307 if !self.trait_ref_hack || !trait_ref.bound_lifetimes.is_empty() {
308 if self.trait_ref_hack {
309 println!("{:?}", trait_ref.span);
310 span_err!(self.sess, trait_ref.span, E0316,
311 "nested quantification of lifetimes");
313 self.with(LateScope(&trait_ref.bound_lifetimes, self.scope), |old_scope, this| {
314 this.check_lifetime_defs(old_scope, &trait_ref.bound_lifetimes);
315 for lifetime in &trait_ref.bound_lifetimes {
316 this.visit_lifetime_def(lifetime);
318 intravisit::walk_path(this, &trait_ref.trait_ref.path)
321 self.visit_trait_ref(&trait_ref.trait_ref)
326 #[derive(Copy, Clone, PartialEq)]
327 enum ShadowKind { Label, Lifetime }
328 struct Original { kind: ShadowKind, span: Span }
329 struct Shadower { kind: ShadowKind, span: Span }
331 fn original_label(span: Span) -> Original {
332 Original { kind: ShadowKind::Label, span: span }
334 fn shadower_label(span: Span) -> Shadower {
335 Shadower { kind: ShadowKind::Label, span: span }
337 fn original_lifetime(l: &hir::Lifetime) -> Original {
338 Original { kind: ShadowKind::Lifetime, span: l.span }
340 fn shadower_lifetime(l: &hir::Lifetime) -> Shadower {
341 Shadower { kind: ShadowKind::Lifetime, span: l.span }
345 fn desc(&self) -> &'static str {
347 ShadowKind::Label => "label",
348 ShadowKind::Lifetime => "lifetime",
353 fn signal_shadowing_problem(
354 sess: &Session, name: ast::Name, orig: Original, shadower: Shadower) {
355 if let (ShadowKind::Lifetime, ShadowKind::Lifetime) = (orig.kind, shadower.kind) {
356 // lifetime/lifetime shadowing is an error
357 span_err!(sess, shadower.span, E0496,
358 "{} name `{}` shadows a \
359 {} name that is already in scope",
360 shadower.kind.desc(), name, orig.kind.desc());
362 // shadowing involving a label is only a warning, due to issues with
363 // labels and lifetimes not being macro-hygienic.
364 sess.span_warn(shadower.span,
365 &format!("{} name `{}` shadows a \
366 {} name that is already in scope",
367 shadower.kind.desc(), name, orig.kind.desc()));
369 sess.span_note(orig.span,
370 &format!("shadowed {} `{}` declared here",
371 orig.kind.desc(), name));
374 // Adds all labels in `b` to `ctxt.labels_in_fn`, signalling a warning
375 // if one of the label shadows a lifetime or another label.
376 fn extract_labels<'v, 'a>(ctxt: &mut LifetimeContext<'a>, b: &'v hir::Block) {
378 struct GatherLabels<'a> {
381 labels_in_fn: &'a mut Vec<(ast::Name, Span)>,
384 let mut gather = GatherLabels {
387 labels_in_fn: &mut ctxt.labels_in_fn,
389 gather.visit_block(b);
392 impl<'v, 'a> Visitor<'v> for GatherLabels<'a> {
393 fn visit_expr(&mut self, ex: &'v hir::Expr) {
394 // do not recurse into closures defined in the block
395 // since they are treated as separate fns from the POV of
397 if let hir::ExprClosure(..) = ex.node {
400 if let Some(label) = expression_label(ex) {
401 for &(prior, prior_span) in &self.labels_in_fn[..] {
402 // FIXME (#24278): non-hygienic comparison
404 signal_shadowing_problem(self.sess,
406 original_label(prior_span),
407 shadower_label(ex.span));
411 check_if_label_shadows_lifetime(self.sess,
416 self.labels_in_fn.push((label, ex.span));
418 intravisit::walk_expr(self, ex)
421 fn visit_item(&mut self, _: &hir::Item) {
422 // do not recurse into items defined in the block
426 fn expression_label(ex: &hir::Expr) -> Option<ast::Name> {
428 hir::ExprWhile(_, _, Some(label)) |
429 hir::ExprLoop(_, Some(label)) => Some(label.name),
434 fn check_if_label_shadows_lifetime<'a>(sess: &'a Session,
435 mut scope: Scope<'a>,
440 BlockScope(_, s) => { scope = s; }
441 RootScope => { return; }
443 EarlyScope(_, lifetimes, s) |
444 LateScope(lifetimes, s) => {
445 for lifetime_def in lifetimes {
446 // FIXME (#24278): non-hygienic comparison
447 if label == lifetime_def.lifetime.name {
448 signal_shadowing_problem(
451 original_lifetime(&lifetime_def.lifetime),
452 shadower_label(label_span));
463 impl<'a> LifetimeContext<'a> {
464 // This is just like intravisit::walk_fn, except that it extracts the
465 // labels of the function body and swaps them in before visiting
466 // the function body itself.
467 fn walk_fn<'b>(&mut self,
473 FnKind::ItemFn(_, generics, _, _, _, _) => {
474 intravisit::walk_fn_decl(self, fd);
475 self.visit_generics(generics);
477 FnKind::Method(_, sig, _) => {
478 intravisit::walk_fn_decl(self, fd);
479 self.visit_generics(&sig.generics);
480 self.visit_explicit_self(&sig.explicit_self);
482 FnKind::Closure(..) => {
483 intravisit::walk_fn_decl(self, fd);
487 // After inpsecting the decl, add all labels from the body to
488 // `self.labels_in_fn`.
489 extract_labels(self, fb);
491 self.visit_block(fb);
494 fn with<F>(&mut self, wrap_scope: ScopeChain, f: F) where
495 F: FnOnce(Scope, &mut LifetimeContext),
497 let LifetimeContext {sess, ref mut named_region_map, ..} = *self;
498 let mut this = LifetimeContext {
500 named_region_map: *named_region_map,
502 def_map: self.def_map,
503 trait_ref_hack: self.trait_ref_hack,
504 labels_in_fn: self.labels_in_fn.clone(),
506 debug!("entering scope {:?}", this.scope);
507 f(self.scope, &mut this);
508 debug!("exiting scope {:?}", this.scope);
511 /// Visits self by adding a scope and handling recursive walk over the contents with `walk`.
513 /// Handles visiting fns and methods. These are a bit complicated because we must distinguish
514 /// early- vs late-bound lifetime parameters. We do this by checking which lifetimes appear
515 /// within type bounds; those are early bound lifetimes, and the rest are late bound.
519 /// fn foo<'a,'b,'c,T:Trait<'b>>(...)
521 /// Here `'a` and `'c` are late bound but `'b` is early bound. Note that early- and late-bound
522 /// lifetimes may be interspersed together.
524 /// If early bound lifetimes are present, we separate them into their own list (and likewise
525 /// for late bound). They will be numbered sequentially, starting from the lowest index that is
526 /// already in scope (for a fn item, that will be 0, but for a method it might not be). Late
527 /// bound lifetimes are resolved by name and associated with a binder id (`binder_id`), so the
528 /// ordering is not important there.
529 fn visit_early_late<F>(&mut self,
530 early_space: subst::ParamSpace,
531 generics: &hir::Generics,
533 F: FnOnce(&mut LifetimeContext),
535 let referenced_idents = early_bound_lifetime_names(generics);
537 debug!("visit_early_late: referenced_idents={:?}",
540 let (early, late): (Vec<_>, _) = generics.lifetimes.iter().cloned().partition(
541 |l| referenced_idents.iter().any(|&i| i == l.lifetime.name));
543 self.with(EarlyScope(early_space, &early, self.scope), move |old_scope, this| {
544 this.with(LateScope(&late, this.scope), move |_, this| {
545 this.check_lifetime_defs(old_scope, &generics.lifetimes);
551 fn resolve_lifetime_ref(&mut self, lifetime_ref: &hir::Lifetime) {
552 // Walk up the scope chain, tracking the number of fn scopes
553 // that we pass through, until we find a lifetime with the
554 // given name or we run out of scopes. If we encounter a code
555 // block, then the lifetime is not bound but free, so switch
556 // over to `resolve_free_lifetime_ref()` to complete the
558 let mut late_depth = 0;
559 let mut scope = self.scope;
562 BlockScope(blk_scope, s) => {
563 return self.resolve_free_lifetime_ref(blk_scope, lifetime_ref, s);
570 EarlyScope(space, lifetimes, s) => {
571 match search_lifetimes(lifetimes, lifetime_ref) {
572 Some((index, lifetime_def)) => {
573 let decl_id = lifetime_def.id;
574 let def = DefEarlyBoundRegion(space, index, decl_id);
575 self.insert_lifetime(lifetime_ref, def);
584 LateScope(lifetimes, s) => {
585 match search_lifetimes(lifetimes, lifetime_ref) {
586 Some((_index, lifetime_def)) => {
587 let decl_id = lifetime_def.id;
588 let debruijn = ty::DebruijnIndex::new(late_depth + 1);
589 let def = DefLateBoundRegion(debruijn, decl_id);
590 self.insert_lifetime(lifetime_ref, def);
603 self.unresolved_lifetime_ref(lifetime_ref);
606 fn resolve_free_lifetime_ref(&mut self,
607 scope_data: region::DestructionScopeData,
608 lifetime_ref: &hir::Lifetime,
610 debug!("resolve_free_lifetime_ref \
611 scope_data: {:?} lifetime_ref: {:?} scope: {:?}",
612 scope_data, lifetime_ref, scope);
614 // Walk up the scope chain, tracking the outermost free scope,
615 // until we encounter a scope that contains the named lifetime
616 // or we run out of scopes.
617 let mut scope_data = scope_data;
618 let mut scope = scope;
619 let mut search_result = None;
621 debug!("resolve_free_lifetime_ref \
622 scope_data: {:?} scope: {:?} search_result: {:?}",
623 scope_data, scope, search_result);
625 BlockScope(blk_scope_data, s) => {
626 scope_data = blk_scope_data;
634 EarlyScope(_, lifetimes, s) |
635 LateScope(lifetimes, s) => {
636 search_result = search_lifetimes(lifetimes, lifetime_ref);
637 if search_result.is_some() {
645 match search_result {
646 Some((_depth, lifetime)) => {
647 let def = DefFreeRegion(scope_data, lifetime.id);
648 self.insert_lifetime(lifetime_ref, def);
652 self.unresolved_lifetime_ref(lifetime_ref);
658 fn unresolved_lifetime_ref(&self, lifetime_ref: &hir::Lifetime) {
659 span_err!(self.sess, lifetime_ref.span, E0261,
660 "use of undeclared lifetime name `{}`",
664 fn check_lifetime_defs(&mut self, old_scope: Scope, lifetimes: &Vec<hir::LifetimeDef>) {
665 for i in 0..lifetimes.len() {
666 let lifetime_i = &lifetimes[i];
668 let special_idents = [special_idents::static_lifetime];
669 for lifetime in lifetimes {
670 if special_idents.iter().any(|&i| i.name == lifetime.lifetime.name) {
671 span_err!(self.sess, lifetime.lifetime.span, E0262,
672 "invalid lifetime parameter name: `{}`", lifetime.lifetime.name);
676 // It is a hard error to shadow a lifetime within the same scope.
677 for j in i + 1..lifetimes.len() {
678 let lifetime_j = &lifetimes[j];
680 if lifetime_i.lifetime.name == lifetime_j.lifetime.name {
681 span_err!(self.sess, lifetime_j.lifetime.span, E0263,
682 "lifetime name `{}` declared twice in \
684 lifetime_j.lifetime.name);
688 // It is a soft error to shadow a lifetime within a parent scope.
689 self.check_lifetime_def_for_shadowing(old_scope, &lifetime_i.lifetime);
691 for bound in &lifetime_i.bounds {
692 self.resolve_lifetime_ref(bound);
697 fn check_lifetime_def_for_shadowing(&self,
698 mut old_scope: Scope,
699 lifetime: &hir::Lifetime)
701 for &(label, label_span) in &self.labels_in_fn {
702 // FIXME (#24278): non-hygienic comparison
703 if lifetime.name == label {
704 signal_shadowing_problem(self.sess,
706 original_label(label_span),
707 shadower_lifetime(&lifetime));
714 BlockScope(_, s) => {
722 EarlyScope(_, lifetimes, s) |
723 LateScope(lifetimes, s) => {
724 if let Some((_, lifetime_def)) = search_lifetimes(lifetimes, lifetime) {
725 signal_shadowing_problem(
728 original_lifetime(&lifetime_def),
729 shadower_lifetime(&lifetime));
739 fn insert_lifetime(&mut self,
740 lifetime_ref: &hir::Lifetime,
742 if lifetime_ref.id == ast::DUMMY_NODE_ID {
743 self.sess.span_bug(lifetime_ref.span,
744 "lifetime reference not renumbered, \
745 probably a bug in syntax::fold");
748 debug!("lifetime_ref={:?} id={:?} resolved to {:?}",
749 lifetime_to_string(lifetime_ref),
752 self.named_region_map.insert(lifetime_ref.id, def);
756 fn search_lifetimes<'a>(lifetimes: &'a Vec<hir::LifetimeDef>,
757 lifetime_ref: &hir::Lifetime)
758 -> Option<(u32, &'a hir::Lifetime)> {
759 for (i, lifetime_decl) in lifetimes.iter().enumerate() {
760 if lifetime_decl.lifetime.name == lifetime_ref.name {
761 return Some((i as u32, &lifetime_decl.lifetime));
767 ///////////////////////////////////////////////////////////////////////////
769 pub fn early_bound_lifetimes<'a>(generics: &'a hir::Generics) -> Vec<hir::LifetimeDef> {
770 let referenced_idents = early_bound_lifetime_names(generics);
771 if referenced_idents.is_empty() {
775 generics.lifetimes.iter()
776 .filter(|l| referenced_idents.iter().any(|&i| i == l.lifetime.name))
781 /// Given a set of generic declarations, returns a list of names containing all early bound
782 /// lifetime names for those generics. (In fact, this list may also contain other names.)
783 fn early_bound_lifetime_names(generics: &hir::Generics) -> Vec<ast::Name> {
784 // Create two lists, dividing the lifetimes into early/late bound.
785 // Initially, all of them are considered late, but we will move
786 // things from late into early as we go if we find references to
788 let mut early_bound = Vec::new();
789 let mut late_bound = generics.lifetimes.iter()
790 .map(|l| l.lifetime.name)
793 // Any lifetime that appears in a type bound is early.
796 FreeLifetimeCollector { early_bound: &mut early_bound,
797 late_bound: &mut late_bound };
798 for ty_param in generics.ty_params.iter() {
799 walk_list!(&mut collector, visit_ty_param_bound, &ty_param.bounds);
801 for predicate in &generics.where_clause.predicates {
803 &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate{ref bounds,
806 collector.visit_ty(&**bounded_ty);
807 walk_list!(&mut collector, visit_ty_param_bound, bounds);
809 &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate{ref lifetime,
812 collector.visit_lifetime(lifetime);
814 for bound in bounds {
815 collector.visit_lifetime(bound);
818 &hir::WherePredicate::EqPredicate(_) => unimplemented!()
823 // Any lifetime that either has a bound or is referenced by a
825 for lifetime_def in &generics.lifetimes {
826 if !lifetime_def.bounds.is_empty() {
827 shuffle(&mut early_bound, &mut late_bound,
828 lifetime_def.lifetime.name);
829 for bound in &lifetime_def.bounds {
830 shuffle(&mut early_bound, &mut late_bound,
837 struct FreeLifetimeCollector<'a> {
838 early_bound: &'a mut Vec<ast::Name>,
839 late_bound: &'a mut Vec<ast::Name>,
842 impl<'a, 'v> Visitor<'v> for FreeLifetimeCollector<'a> {
843 fn visit_lifetime(&mut self, lifetime_ref: &hir::Lifetime) {
844 shuffle(self.early_bound, self.late_bound,
849 fn shuffle(early_bound: &mut Vec<ast::Name>,
850 late_bound: &mut Vec<ast::Name>,
852 match late_bound.iter().position(|n| *n == name) {
854 late_bound.swap_remove(index);
855 early_bound.push(name);
862 impl<'a> fmt::Debug for ScopeChain<'a> {
863 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
865 EarlyScope(space, defs, _) => write!(fmt, "EarlyScope({:?}, {:?})", space, defs),
866 LateScope(defs, _) => write!(fmt, "LateScope({:?})", defs),
867 BlockScope(id, _) => write!(fmt, "BlockScope({:?})", id),
868 RootScope => write!(fmt, "RootScope"),