1 // Copyright 2012-2014 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.
15 The collect phase of type check has the job of visiting all items,
16 determining their type, and writing that type into the `tcx.tcache`
17 table. Despite its name, this table does not really operate as a
18 *cache*, at least not for the types of items defined within the
19 current crate: we assume that after the collect phase, the types of
20 all local items will be present in the table.
22 Unlike most of the types that are present in Rust, the types computed
23 for each item are in fact type schemes. This means that they are
24 generic types that may have type parameters. TypeSchemes are
25 represented by an instance of `ty::TypeScheme`. This combines the
26 core type along with a list of the bounds for each parameter. Type
27 parameters themselves are represented as `ty_param()` instances.
29 The phasing of type conversion is somewhat complicated. There is no
30 clear set of phases we can enforce (e.g., converting traits first,
31 then types, or something like that) because the user can introduce
32 arbitrary interdependencies. So instead we generally convert things
33 lazilly and on demand, and include logic that checks for cycles.
34 Demand is driven by calls to `AstConv::get_item_type_scheme` or
35 `AstConv::lookup_trait_def`.
37 Currently, we "convert" types and traits in two phases (note that
38 conversion only affects the types of items / enum variants / methods;
39 it does not e.g. compute the types of individual expressions):
42 1. Trait/Type definitions
44 Conversion itself is done by simply walking each of the items in turn
45 and invoking an appropriate function (e.g., `trait_def_of_item` or
46 `convert_item`). However, it is possible that while converting an
47 item, we may need to compute the *type scheme* or *trait definition*
50 There are some shortcomings in this design:
52 - Before walking the set of supertraits for a given trait, you must
53 call `ensure_super_predicates` on that trait def-id. Otherwise,
54 `lookup_super_predicates` will result in ICEs.
55 - Because the type scheme includes defaults, cycles through type
56 parameter defaults are illegal even if those defaults are never
57 employed. This is not necessarily a bug.
61 use astconv::{self, AstConv, ty_of_arg, ast_ty_to_ty, ast_region_to_region};
64 use middle::def_id::DefId;
65 use constrained_type_params as ctp;
66 use middle::lang_items::SizedTraitLangItem;
67 use middle::resolve_lifetime;
68 use middle::const_eval::{self, ConstVal};
69 use middle::const_eval::EvalHint::UncheckedExprHint;
70 use middle::subst::{Substs, FnSpace, ParamSpace, SelfSpace, TypeSpace, VecPerParamSpace};
71 use middle::ty::{ToPredicate, ImplContainer, ImplOrTraitItemContainer, TraitContainer};
72 use middle::ty::{self, ToPolyTraitRef, Ty, TypeScheme};
73 use middle::ty::{VariantKind};
74 use middle::ty::fold::{TypeFolder};
75 use middle::ty::util::IntTypeExt;
77 use rustc::dep_graph::DepNode;
78 use rustc::front::map as hir_map;
79 use util::common::{ErrorReported, MemoizationMap};
80 use util::nodemap::{FnvHashMap, FnvHashSet};
83 use std::cell::RefCell;
84 use std::collections::HashSet;
90 use syntax::codemap::Span;
91 use syntax::parse::token::special_idents;
94 use rustc_front::intravisit;
95 use rustc_front::print::pprust;
97 ///////////////////////////////////////////////////////////////////////////
100 pub fn collect_item_types(tcx: &ty::ctxt) {
101 let ccx = &CrateCtxt { tcx: tcx, stack: RefCell::new(Vec::new()) };
103 let mut visitor = CollectItemTypesVisitor{ ccx: ccx };
104 ccx.tcx.map.krate().visit_all_items(&mut visitor);
107 ///////////////////////////////////////////////////////////////////////////
109 struct CrateCtxt<'a,'tcx:'a> {
110 tcx: &'a ty::ctxt<'tcx>,
112 // This stack is used to identify cycles in the user's source.
113 // Note that these cycles can cross multiple items.
114 stack: RefCell<Vec<AstConvRequest>>,
117 /// Context specific to some particular item. This is what implements
118 /// AstConv. It has information about the predicates that are defined
119 /// on the trait. Unfortunately, this predicate information is
120 /// available in various different forms at various points in the
121 /// process. So we can't just store a pointer to e.g. the AST or the
122 /// parsed ty form, we have to be more flexible. To this end, the
123 /// `ItemCtxt` is parameterized by a `GetTypeParameterBounds` object
124 /// that it uses to satisfy `get_type_parameter_bounds` requests.
125 /// This object might draw the information from the AST
126 /// (`hir::Generics`) or it might draw from a `ty::GenericPredicates`
127 /// or both (a tuple).
128 struct ItemCtxt<'a,'tcx:'a> {
129 ccx: &'a CrateCtxt<'a,'tcx>,
130 param_bounds: &'a (GetTypeParameterBounds<'tcx>+'a),
133 #[derive(Copy, Clone, PartialEq, Eq)]
134 enum AstConvRequest {
135 GetItemTypeScheme(DefId),
137 EnsureSuperPredicates(DefId),
138 GetTypeParameterBounds(ast::NodeId),
141 ///////////////////////////////////////////////////////////////////////////
143 struct CollectItemTypesVisitor<'a, 'tcx: 'a> {
144 ccx: &'a CrateCtxt<'a, 'tcx>
147 impl<'a, 'tcx, 'v> intravisit::Visitor<'v> for CollectItemTypesVisitor<'a, 'tcx> {
148 fn visit_item(&mut self, item: &hir::Item) {
149 let tcx = self.ccx.tcx;
150 let item_def_id = tcx.map.local_def_id(item.id);
151 let _task = tcx.dep_graph.in_task(DepNode::CollectItem(item_def_id));
152 convert_item(self.ccx, item);
156 ///////////////////////////////////////////////////////////////////////////
157 // Utility types and common code for the above passes.
159 impl<'a,'tcx> CrateCtxt<'a,'tcx> {
160 fn icx(&'a self, param_bounds: &'a GetTypeParameterBounds<'tcx>) -> ItemCtxt<'a,'tcx> {
161 ItemCtxt { ccx: self, param_bounds: param_bounds }
164 fn cycle_check<F,R>(&self,
166 request: AstConvRequest,
168 -> Result<R,ErrorReported>
169 where F: FnOnce() -> Result<R,ErrorReported>
172 let mut stack = self.stack.borrow_mut();
173 match stack.iter().enumerate().rev().find(|&(_, r)| *r == request) {
176 let cycle = &stack[i..];
177 self.report_cycle(span, cycle);
178 return Err(ErrorReported);
186 self.stack.borrow_mut().pop();
190 fn report_cycle(&self,
192 cycle: &[AstConvRequest])
194 assert!(!cycle.is_empty());
197 let mut err = struct_span_err!(tcx.sess, span, E0391,
198 "unsupported cyclic reference between types/traits detected");
201 AstConvRequest::GetItemTypeScheme(def_id) |
202 AstConvRequest::GetTraitDef(def_id) => {
204 &format!("the cycle begins when processing `{}`...",
205 tcx.item_path_str(def_id)));
207 AstConvRequest::EnsureSuperPredicates(def_id) => {
209 &format!("the cycle begins when computing the supertraits of `{}`...",
210 tcx.item_path_str(def_id)));
212 AstConvRequest::GetTypeParameterBounds(id) => {
213 let def = tcx.type_parameter_def(id);
215 &format!("the cycle begins when computing the bounds \
216 for type parameter `{}`...",
221 for request in &cycle[1..] {
223 AstConvRequest::GetItemTypeScheme(def_id) |
224 AstConvRequest::GetTraitDef(def_id) => {
226 &format!("...which then requires processing `{}`...",
227 tcx.item_path_str(def_id)));
229 AstConvRequest::EnsureSuperPredicates(def_id) => {
231 &format!("...which then requires computing the supertraits of `{}`...",
232 tcx.item_path_str(def_id)));
234 AstConvRequest::GetTypeParameterBounds(id) => {
235 let def = tcx.type_parameter_def(id);
237 &format!("...which then requires computing the bounds \
238 for type parameter `{}`...",
245 AstConvRequest::GetItemTypeScheme(def_id) |
246 AstConvRequest::GetTraitDef(def_id) => {
248 &format!("...which then again requires processing `{}`, completing the cycle.",
249 tcx.item_path_str(def_id)));
251 AstConvRequest::EnsureSuperPredicates(def_id) => {
253 &format!("...which then again requires computing the supertraits of `{}`, \
254 completing the cycle.",
255 tcx.item_path_str(def_id)));
257 AstConvRequest::GetTypeParameterBounds(id) => {
258 let def = tcx.type_parameter_def(id);
260 &format!("...which then again requires computing the bounds \
261 for type parameter `{}`, completing the cycle.",
268 /// Loads the trait def for a given trait, returning ErrorReported if a cycle arises.
269 fn get_trait_def(&self, trait_id: DefId)
270 -> &'tcx ty::TraitDef<'tcx>
274 if let Some(trait_id) = tcx.map.as_local_node_id(trait_id) {
275 let item = match tcx.map.get(trait_id) {
276 hir_map::NodeItem(item) => item,
277 _ => tcx.sess.bug(&format!("get_trait_def({:?}): not an item", trait_id))
280 trait_def_of_item(self, &*item)
282 tcx.lookup_trait_def(trait_id)
286 /// Ensure that the (transitive) super predicates for
287 /// `trait_def_id` are available. This will report a cycle error
288 /// if a trait `X` (transitively) extends itself in some form.
289 fn ensure_super_predicates(&self, span: Span, trait_def_id: DefId)
290 -> Result<(), ErrorReported>
292 self.cycle_check(span, AstConvRequest::EnsureSuperPredicates(trait_def_id), || {
293 let def_ids = ensure_super_predicates_step(self, trait_def_id);
295 for def_id in def_ids {
296 try!(self.ensure_super_predicates(span, def_id));
304 impl<'a,'tcx> ItemCtxt<'a,'tcx> {
305 fn to_ty<RS:RegionScope>(&self, rs: &RS, ast_ty: &hir::Ty) -> Ty<'tcx> {
306 ast_ty_to_ty(self, rs, ast_ty)
310 impl<'a, 'tcx> AstConv<'tcx> for ItemCtxt<'a, 'tcx> {
311 fn tcx(&self) -> &ty::ctxt<'tcx> { self.ccx.tcx }
313 fn get_item_type_scheme(&self, span: Span, id: DefId)
314 -> Result<ty::TypeScheme<'tcx>, ErrorReported>
316 self.ccx.cycle_check(span, AstConvRequest::GetItemTypeScheme(id), || {
317 Ok(type_scheme_of_def_id(self.ccx, id))
321 fn get_trait_def(&self, span: Span, id: DefId)
322 -> Result<&'tcx ty::TraitDef<'tcx>, ErrorReported>
324 self.ccx.cycle_check(span, AstConvRequest::GetTraitDef(id), || {
325 Ok(self.ccx.get_trait_def(id))
329 fn ensure_super_predicates(&self,
332 -> Result<(), ErrorReported>
334 debug!("ensure_super_predicates(trait_def_id={:?})",
337 self.ccx.ensure_super_predicates(span, trait_def_id)
341 fn get_type_parameter_bounds(&self,
343 node_id: ast::NodeId)
344 -> Result<Vec<ty::PolyTraitRef<'tcx>>, ErrorReported>
346 self.ccx.cycle_check(span, AstConvRequest::GetTypeParameterBounds(node_id), || {
347 let v = self.param_bounds.get_type_parameter_bounds(self, span, node_id)
349 .filter_map(|p| p.to_opt_poly_trait_ref())
355 fn trait_defines_associated_type_named(&self,
357 assoc_name: ast::Name)
360 if let Some(trait_id) = self.tcx().map.as_local_node_id(trait_def_id) {
361 trait_defines_associated_type_named(self.ccx, trait_id, assoc_name)
363 let trait_def = self.tcx().lookup_trait_def(trait_def_id);
364 trait_def.associated_type_names.contains(&assoc_name)
369 _ty_param_def: Option<ty::TypeParameterDef<'tcx>>,
370 _substs: Option<&mut Substs<'tcx>>,
371 _space: Option<ParamSpace>,
372 span: Span) -> Ty<'tcx> {
373 span_err!(self.tcx().sess, span, E0121,
374 "the type placeholder `_` is not allowed within types on item signatures");
378 fn projected_ty(&self,
380 trait_ref: ty::TraitRef<'tcx>,
381 item_name: ast::Name)
384 self.tcx().mk_projection(trait_ref, item_name)
388 /// Interface used to find the bounds on a type parameter from within
389 /// an `ItemCtxt`. This allows us to use multiple kinds of sources.
390 trait GetTypeParameterBounds<'tcx> {
391 fn get_type_parameter_bounds(&self,
392 astconv: &AstConv<'tcx>,
394 node_id: ast::NodeId)
395 -> Vec<ty::Predicate<'tcx>>;
398 /// Find bounds from both elements of the tuple.
399 impl<'a,'b,'tcx,A,B> GetTypeParameterBounds<'tcx> for (&'a A,&'b B)
400 where A : GetTypeParameterBounds<'tcx>, B : GetTypeParameterBounds<'tcx>
402 fn get_type_parameter_bounds(&self,
403 astconv: &AstConv<'tcx>,
405 node_id: ast::NodeId)
406 -> Vec<ty::Predicate<'tcx>>
408 let mut v = self.0.get_type_parameter_bounds(astconv, span, node_id);
409 v.extend(self.1.get_type_parameter_bounds(astconv, span, node_id));
414 /// Empty set of bounds.
415 impl<'tcx> GetTypeParameterBounds<'tcx> for () {
416 fn get_type_parameter_bounds(&self,
417 _astconv: &AstConv<'tcx>,
419 _node_id: ast::NodeId)
420 -> Vec<ty::Predicate<'tcx>>
426 /// Find bounds from the parsed and converted predicates. This is
427 /// used when converting methods, because by that time the predicates
428 /// from the trait/impl have been fully converted.
429 impl<'tcx> GetTypeParameterBounds<'tcx> for ty::GenericPredicates<'tcx> {
430 fn get_type_parameter_bounds(&self,
431 astconv: &AstConv<'tcx>,
433 node_id: ast::NodeId)
434 -> Vec<ty::Predicate<'tcx>>
436 let def = astconv.tcx().type_parameter_def(node_id);
440 .filter(|predicate| {
442 ty::Predicate::Trait(ref data) => {
443 data.skip_binder().self_ty().is_param(def.space, def.index)
445 ty::Predicate::TypeOutlives(ref data) => {
446 data.skip_binder().0.is_param(def.space, def.index)
448 ty::Predicate::Equate(..) |
449 ty::Predicate::RegionOutlives(..) |
450 ty::Predicate::WellFormed(..) |
451 ty::Predicate::ObjectSafe(..) |
452 ty::Predicate::Projection(..) => {
462 /// Find bounds from hir::Generics. This requires scanning through the
463 /// AST. We do this to avoid having to convert *all* the bounds, which
464 /// would create artificial cycles. Instead we can only convert the
465 /// bounds for a type parameter `X` if `X::Foo` is used.
466 impl<'tcx> GetTypeParameterBounds<'tcx> for hir::Generics {
467 fn get_type_parameter_bounds(&self,
468 astconv: &AstConv<'tcx>,
470 node_id: ast::NodeId)
471 -> Vec<ty::Predicate<'tcx>>
473 // In the AST, bounds can derive from two places. Either
474 // written inline like `<T:Foo>` or in a where clause like
477 let def = astconv.tcx().type_parameter_def(node_id);
478 let ty = astconv.tcx().mk_param_from_def(&def);
483 .filter(|p| p.id == node_id)
484 .flat_map(|p| p.bounds.iter())
485 .flat_map(|b| predicates_from_bound(astconv, ty, b));
487 let from_where_clauses =
491 .filter_map(|wp| match *wp {
492 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
495 .filter(|bp| is_param(astconv.tcx(), &bp.bounded_ty, node_id))
496 .flat_map(|bp| bp.bounds.iter())
497 .flat_map(|b| predicates_from_bound(astconv, ty, b));
499 from_ty_params.chain(from_where_clauses).collect()
503 /// Tests whether this is the AST for a reference to the type
504 /// parameter with id `param_id`. We use this so as to avoid running
505 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
506 /// conversion of the type to avoid inducing unnecessary cycles.
507 fn is_param<'tcx>(tcx: &ty::ctxt<'tcx>,
509 param_id: ast::NodeId)
512 if let hir::TyPath(None, _) = ast_ty.node {
513 let path_res = *tcx.def_map.borrow().get(&ast_ty.id).unwrap();
514 match path_res.base_def {
515 def::DefSelfTy(Some(def_id), None) => {
516 path_res.depth == 0 && def_id == tcx.map.local_def_id(param_id)
518 def::DefTyParam(_, _, def_id, _) => {
519 path_res.depth == 0 && def_id == tcx.map.local_def_id(param_id)
531 fn convert_method<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
532 container: ImplOrTraitItemContainer,
535 vis: hir::Visibility,
536 sig: &hir::MethodSig,
537 untransformed_rcvr_ty: Ty<'tcx>,
538 rcvr_ty_generics: &ty::Generics<'tcx>,
539 rcvr_ty_predicates: &ty::GenericPredicates<'tcx>) {
540 let ty_generics = ty_generics_for_fn(ccx, &sig.generics, rcvr_ty_generics);
542 let ty_generic_predicates =
543 ty_generic_predicates_for_fn(ccx, &sig.generics, rcvr_ty_predicates);
545 let (fty, explicit_self_category) =
546 astconv::ty_of_method(&ccx.icx(&(rcvr_ty_predicates, &sig.generics)),
547 sig, untransformed_rcvr_ty);
549 let def_id = ccx.tcx.map.local_def_id(id);
550 let ty_method = ty::Method::new(name,
552 ty_generic_predicates,
554 explicit_self_category,
559 let fty = ccx.tcx.mk_fn(Some(def_id),
560 ccx.tcx.mk_bare_fn(ty_method.fty.clone()));
561 debug!("method {} (id {}) has type {:?}",
563 ccx.tcx.register_item_type(def_id, TypeScheme {
564 generics: ty_method.generics.clone(),
567 ccx.tcx.predicates.borrow_mut().insert(def_id, ty_method.predicates.clone());
569 write_ty_to_tcx(ccx.tcx, id, fty);
571 debug!("writing method type: def_id={:?} mty={:?}",
574 ccx.tcx.impl_or_trait_items.borrow_mut().insert(def_id,
575 ty::MethodTraitItem(Rc::new(ty_method)));
578 fn convert_field<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
579 struct_generics: &ty::Generics<'tcx>,
580 struct_predicates: &ty::GenericPredicates<'tcx>,
581 v: &hir::StructField,
582 ty_f: ty::FieldDefMaster<'tcx>)
584 let tt = ccx.icx(struct_predicates).to_ty(&ExplicitRscope, &*v.node.ty);
586 write_ty_to_tcx(ccx.tcx, v.node.id, tt);
588 /* add the field to the tcache */
589 ccx.tcx.register_item_type(ccx.tcx.map.local_def_id(v.node.id),
591 generics: struct_generics.clone(),
594 ccx.tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(v.node.id),
595 struct_predicates.clone());
598 fn convert_associated_const<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
599 container: ImplOrTraitItemContainer,
602 vis: hir::Visibility,
606 ccx.tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(id),
607 ty::GenericPredicates::empty());
609 write_ty_to_tcx(ccx.tcx, id, ty);
611 let associated_const = Rc::new(ty::AssociatedConst {
614 def_id: ccx.tcx.map.local_def_id(id),
615 container: container,
619 ccx.tcx.impl_or_trait_items.borrow_mut()
620 .insert(ccx.tcx.map.local_def_id(id), ty::ConstTraitItem(associated_const));
623 fn convert_associated_type<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
624 container: ImplOrTraitItemContainer,
627 vis: hir::Visibility,
628 ty: Option<Ty<'tcx>>)
630 let associated_type = Rc::new(ty::AssociatedType {
634 def_id: ccx.tcx.map.local_def_id(id),
637 ccx.tcx.impl_or_trait_items.borrow_mut()
638 .insert(ccx.tcx.map.local_def_id(id), ty::TypeTraitItem(associated_type));
641 fn ensure_no_ty_param_bounds(ccx: &CrateCtxt,
643 generics: &hir::Generics,
644 thing: &'static str) {
645 let mut warn = false;
647 for ty_param in generics.ty_params.iter() {
648 for bound in ty_param.bounds.iter() {
650 hir::TraitTyParamBound(..) => {
653 hir::RegionTyParamBound(..) => { }
659 // According to accepted RFC #XXX, we should
660 // eventually accept these, but it will not be
661 // part of this PR. Still, convert to warning to
662 // make bootstrapping easier.
663 span_warn!(ccx.tcx.sess, span, E0122,
664 "trait bounds are not (yet) enforced \
670 fn convert_item(ccx: &CrateCtxt, it: &hir::Item) {
672 debug!("convert: item {} with id {}", it.name, it.id);
674 // These don't define types.
675 hir::ItemExternCrate(_) | hir::ItemUse(_) | hir::ItemMod(_) => {
677 hir::ItemForeignMod(ref foreign_mod) => {
678 for item in &foreign_mod.items {
679 convert_foreign_item(ccx, item);
682 hir::ItemEnum(ref enum_definition, _) => {
683 let (scheme, predicates) = convert_typed_item(ccx, it);
684 write_ty_to_tcx(tcx, it.id, scheme.ty);
685 convert_enum_variant_types(ccx,
686 tcx.lookup_adt_def_master(ccx.tcx.map.local_def_id(it.id)),
689 &enum_definition.variants);
691 hir::ItemDefaultImpl(_, ref ast_trait_ref) => {
693 astconv::instantiate_mono_trait_ref(&ccx.icx(&()),
698 tcx.record_trait_has_default_impl(trait_ref.def_id);
700 tcx.impl_trait_refs.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
708 // Create generics from the generics specified in the impl head.
709 debug!("convert: ast_generics={:?}", generics);
710 let def_id = ccx.tcx.map.local_def_id(it.id);
711 let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
712 let mut ty_predicates = ty_generic_predicates_for_type_or_impl(ccx, generics);
714 debug!("convert: impl_bounds={:?}", ty_predicates);
716 let selfty = ccx.icx(&ty_predicates).to_ty(&ExplicitRscope, &**selfty);
717 write_ty_to_tcx(tcx, it.id, selfty);
719 tcx.register_item_type(def_id,
720 TypeScheme { generics: ty_generics.clone(),
722 if let &Some(ref ast_trait_ref) = opt_trait_ref {
723 tcx.impl_trait_refs.borrow_mut().insert(
725 Some(astconv::instantiate_mono_trait_ref(&ccx.icx(&ty_predicates),
731 tcx.impl_trait_refs.borrow_mut().insert(def_id, None);
734 enforce_impl_params_are_constrained(tcx, generics, &mut ty_predicates, def_id);
735 tcx.predicates.borrow_mut().insert(def_id, ty_predicates.clone());
738 // If there is a trait reference, treat the methods as always public.
739 // This is to work around some incorrect behavior in privacy checking:
740 // when the method belongs to a trait, it should acquire the privacy
741 // from the trait, not the impl. Forcing the visibility to be public
742 // makes things sorta work.
743 let parent_visibility = if opt_trait_ref.is_some() {
749 // Convert all the associated consts.
750 // Also, check if there are any duplicate associated items
751 let mut seen_type_items = FnvHashSet();
752 let mut seen_value_items = FnvHashSet();
754 for impl_item in impl_items {
755 let seen_items = match impl_item.node {
756 hir::ImplItemKind::Type(_) => &mut seen_type_items,
757 _ => &mut seen_value_items,
759 if !seen_items.insert(impl_item.name) {
760 let desc = match impl_item.node {
761 hir::ImplItemKind::Const(_, _) => "associated constant",
762 hir::ImplItemKind::Type(_) => "associated type",
763 hir::ImplItemKind::Method(ref sig, _) =>
764 match sig.explicit_self.node {
765 hir::SelfStatic => "associated function",
770 span_err!(tcx.sess, impl_item.span, E0201, "duplicate {}", desc);
773 if let hir::ImplItemKind::Const(ref ty, _) = impl_item.node {
774 let ty = ccx.icx(&ty_predicates)
775 .to_ty(&ExplicitRscope, &*ty);
776 tcx.register_item_type(ccx.tcx.map.local_def_id(impl_item.id),
778 generics: ty_generics.clone(),
781 convert_associated_const(ccx, ImplContainer(def_id),
782 impl_item.name, impl_item.id,
783 impl_item.vis.inherit_from(parent_visibility),
784 ty, true /* has_value */);
788 // Convert all the associated types.
789 for impl_item in impl_items {
790 if let hir::ImplItemKind::Type(ref ty) = impl_item.node {
791 if opt_trait_ref.is_none() {
792 span_err!(tcx.sess, impl_item.span, E0202,
793 "associated types are not allowed in inherent impls");
796 let typ = ccx.icx(&ty_predicates).to_ty(&ExplicitRscope, ty);
798 convert_associated_type(ccx, ImplContainer(def_id),
799 impl_item.name, impl_item.id, impl_item.vis,
804 for impl_item in impl_items {
805 if let hir::ImplItemKind::Method(ref sig, _) = impl_item.node {
806 // if the method specifies a visibility, use that, otherwise
807 // inherit the visibility from the impl (so `foo` in `pub impl
808 // { fn foo(); }` is public, but private in `impl { fn
810 let method_vis = impl_item.vis.inherit_from(parent_visibility);
812 convert_method(ccx, ImplContainer(def_id),
813 impl_item.name, impl_item.id, method_vis,
814 sig, selfty, &ty_generics, &ty_predicates);
818 enforce_impl_lifetimes_are_constrained(tcx, generics, def_id, impl_items);
820 hir::ItemTrait(_, _, _, ref trait_items) => {
821 let trait_def = trait_def_of_item(ccx, it);
822 let def_id = trait_def.trait_ref.def_id;
823 let _: Result<(), ErrorReported> = // any error is already reported, can ignore
824 ccx.ensure_super_predicates(it.span, def_id);
825 convert_trait_predicates(ccx, it);
826 let trait_predicates = tcx.lookup_predicates(def_id);
828 debug!("convert: trait_bounds={:?}", trait_predicates);
830 // FIXME: is the ordering here important? I think it is.
831 let container = TraitContainer(def_id);
833 // Convert all the associated constants.
834 for trait_item in trait_items {
835 if let hir::ConstTraitItem(ref ty, ref default) = trait_item.node {
836 let ty = ccx.icx(&trait_predicates)
837 .to_ty(&ExplicitRscope, ty);
838 tcx.register_item_type(ccx.tcx.map.local_def_id(trait_item.id),
840 generics: trait_def.generics.clone(),
843 convert_associated_const(ccx,
853 // Convert all the associated types.
854 for trait_item in trait_items {
855 if let hir::TypeTraitItem(_, ref opt_ty) = trait_item.node {
856 let typ = opt_ty.as_ref().map({
857 |ty| ccx.icx(&trait_predicates).to_ty(&ExplicitRscope, &ty)
860 convert_associated_type(ccx,
869 // Convert all the methods
870 for trait_item in trait_items {
871 if let hir::MethodTraitItem(ref sig, _) = trait_item.node {
885 // Add an entry mapping
886 let trait_item_def_ids = Rc::new(trait_items.iter().map(|trait_item| {
887 let def_id = ccx.tcx.map.local_def_id(trait_item.id);
888 match trait_item.node {
889 hir::ConstTraitItem(..) => ty::ConstTraitItemId(def_id),
890 hir::MethodTraitItem(..) => ty::MethodTraitItemId(def_id),
891 hir::TypeTraitItem(..) => ty::TypeTraitItemId(def_id)
894 tcx.trait_item_def_ids.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
897 hir::ItemStruct(ref struct_def, _) => {
898 let (scheme, predicates) = convert_typed_item(ccx, it);
899 write_ty_to_tcx(tcx, it.id, scheme.ty);
901 let it_def_id = ccx.tcx.map.local_def_id(it.id);
902 let variant = tcx.lookup_adt_def_master(it_def_id).struct_variant();
904 for (f, ty_f) in struct_def.fields().iter().zip(variant.fields.iter()) {
905 convert_field(ccx, &scheme.generics, &predicates, f, ty_f)
908 if !struct_def.is_struct() {
909 convert_variant_ctor(tcx, struct_def.id(), variant, scheme, predicates);
912 hir::ItemTy(_, ref generics) => {
913 ensure_no_ty_param_bounds(ccx, it.span, generics, "type");
914 let (scheme, _) = convert_typed_item(ccx, it);
915 write_ty_to_tcx(tcx, it.id, scheme.ty);
918 // This call populates the type cache with the converted type
919 // of the item in passing. All we have to do here is to write
920 // it into the node type table.
921 let (scheme, _) = convert_typed_item(ccx, it);
922 write_ty_to_tcx(tcx, it.id, scheme.ty);
927 fn convert_variant_ctor<'a, 'tcx>(tcx: &ty::ctxt<'tcx>,
928 ctor_id: ast::NodeId,
929 variant: ty::VariantDef<'tcx>,
930 scheme: ty::TypeScheme<'tcx>,
931 predicates: ty::GenericPredicates<'tcx>) {
932 let ctor_ty = match variant.kind() {
933 VariantKind::Unit | VariantKind::Struct => scheme.ty,
934 VariantKind::Tuple => {
938 .map(|field| field.unsubst_ty())
940 tcx.mk_ctor_fn(tcx.map.local_def_id(ctor_id),
945 write_ty_to_tcx(tcx, ctor_id, ctor_ty);
946 tcx.predicates.borrow_mut().insert(tcx.map.local_def_id(ctor_id), predicates);
947 tcx.register_item_type(tcx.map.local_def_id(ctor_id),
949 generics: scheme.generics,
954 fn convert_enum_variant_types<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
955 def: ty::AdtDefMaster<'tcx>,
956 scheme: ty::TypeScheme<'tcx>,
957 predicates: ty::GenericPredicates<'tcx>,
958 variants: &[hir::Variant]) {
959 // fill the field types
960 for (variant, ty_variant) in variants.iter().zip(def.variants.iter()) {
961 for (f, ty_f) in variant.node.data.fields().iter().zip(ty_variant.fields.iter()) {
962 convert_field(ccx, &scheme.generics, &predicates, f, ty_f)
965 // Convert the ctor, if any. This also registers the variant as
967 convert_variant_ctor(
969 variant.node.data.id(),
977 fn convert_struct_variant<'tcx>(tcx: &ty::ctxt<'tcx>,
981 def: &hir::VariantData) -> ty::VariantDefData<'tcx, 'tcx> {
982 let mut seen_fields: FnvHashMap<ast::Name, Span> = FnvHashMap();
983 let fields = def.fields().iter().map(|f| {
984 let fid = tcx.map.local_def_id(f.node.id);
986 hir::NamedField(name, vis) => {
987 let dup_span = seen_fields.get(&name).cloned();
988 if let Some(prev_span) = dup_span {
989 let mut err = struct_span_err!(tcx.sess, f.span, E0124,
990 "field `{}` is already declared",
992 span_note!(&mut err, prev_span, "previously declared here");
995 seen_fields.insert(name, f.span);
998 ty::FieldDefData::new(fid, name, vis)
1000 hir::UnnamedField(vis) => {
1001 ty::FieldDefData::new(fid, special_idents::unnamed_field.name, vis)
1005 ty::VariantDefData {
1010 kind: VariantKind::from_variant_data(def),
1014 fn convert_struct_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1016 def: &hir::VariantData)
1017 -> ty::AdtDefMaster<'tcx>
1020 let did = tcx.map.local_def_id(it.id);
1021 let ctor_id = if !def.is_struct() {
1022 tcx.map.local_def_id(def.id())
1028 ty::AdtKind::Struct,
1029 vec![convert_struct_variant(tcx, ctor_id, it.name, 0, def)]
1033 fn convert_enum_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1036 -> ty::AdtDefMaster<'tcx>
1038 fn evaluate_disr_expr<'tcx>(tcx: &ty::ctxt<'tcx>,
1040 e: &hir::Expr) -> Option<ty::Disr> {
1041 debug!("disr expr, checking {}", pprust::expr_to_string(e));
1043 let hint = UncheckedExprHint(repr_ty);
1044 match const_eval::eval_const_expr_partial(tcx, e, hint, None) {
1045 Ok(ConstVal::Int(val)) => Some(val as ty::Disr),
1046 Ok(ConstVal::Uint(val)) => Some(val as ty::Disr),
1048 let sign_desc = if repr_ty.is_signed() {
1053 span_err!(tcx.sess, e.span, E0079,
1054 "expected {} integer constant",
1059 let mut diag = struct_span_err!(tcx.sess, err.span, E0080,
1060 "constant evaluation error: {}",
1062 if !e.span.contains(err.span) {
1063 diag.span_note(e.span, "for enum discriminant here");
1071 fn report_discrim_overflow(tcx: &ty::ctxt,
1074 repr_type: attr::IntType,
1075 prev_val: ty::Disr) {
1076 let computed_value = repr_type.disr_wrap_incr(Some(prev_val));
1077 let computed_value = repr_type.disr_string(computed_value);
1078 let prev_val = repr_type.disr_string(prev_val);
1079 let repr_type = repr_type.to_ty(tcx);
1080 span_err!(tcx.sess, variant_span, E0370,
1081 "enum discriminant overflowed on value after {}: {}; \
1082 set explicitly via {} = {} if that is desired outcome",
1083 prev_val, repr_type, variant_name, computed_value);
1086 fn next_disr(tcx: &ty::ctxt,
1088 repr_type: attr::IntType,
1089 prev_disr_val: Option<ty::Disr>) -> Option<ty::Disr> {
1090 if let Some(prev_disr_val) = prev_disr_val {
1091 let result = repr_type.disr_incr(prev_disr_val);
1092 if let None = result {
1093 report_discrim_overflow(tcx, v.span, &v.node.name.as_str(),
1094 repr_type, prev_disr_val);
1098 Some(ty::INITIAL_DISCRIMINANT_VALUE)
1101 fn convert_enum_variant<'tcx>(tcx: &ty::ctxt<'tcx>,
1104 -> ty::VariantDefData<'tcx, 'tcx>
1106 let did = tcx.map.local_def_id(v.node.data.id());
1107 let name = v.node.name;
1108 convert_struct_variant(tcx, did, name, disr, &v.node.data)
1110 let did = tcx.map.local_def_id(it.id);
1111 let repr_hints = tcx.lookup_repr_hints(did);
1112 let (repr_type, repr_type_ty) = tcx.enum_repr_type(repr_hints.get(0));
1113 let mut prev_disr = None;
1114 let variants = def.variants.iter().map(|v| {
1115 let disr = match v.node.disr_expr {
1116 Some(ref e) => evaluate_disr_expr(tcx, repr_type_ty, e),
1117 None => next_disr(tcx, v, repr_type, prev_disr)
1118 }.unwrap_or(repr_type.disr_wrap_incr(prev_disr));
1120 let v = convert_enum_variant(tcx, v, disr);
1121 prev_disr = Some(disr);
1124 tcx.intern_adt_def(tcx.map.local_def_id(it.id), ty::AdtKind::Enum, variants)
1127 /// Ensures that the super-predicates of the trait with def-id
1128 /// trait_def_id are converted and stored. This does NOT ensure that
1129 /// the transitive super-predicates are converted; that is the job of
1130 /// the `ensure_super_predicates()` method in the `AstConv` impl
1131 /// above. Returns a list of trait def-ids that must be ensured as
1132 /// well to guarantee that the transitive superpredicates are
1134 fn ensure_super_predicates_step(ccx: &CrateCtxt,
1135 trait_def_id: DefId)
1140 debug!("ensure_super_predicates_step(trait_def_id={:?})", trait_def_id);
1142 let trait_node_id = if let Some(n) = tcx.map.as_local_node_id(trait_def_id) {
1145 // If this trait comes from an external crate, then all of the
1146 // supertraits it may depend on also must come from external
1147 // crates, and hence all of them already have their
1148 // super-predicates "converted" (and available from crate
1149 // meta-data), so there is no need to transitively test them.
1153 let superpredicates = tcx.super_predicates.borrow().get(&trait_def_id).cloned();
1154 let superpredicates = superpredicates.unwrap_or_else(|| {
1155 let item = match ccx.tcx.map.get(trait_node_id) {
1156 hir_map::NodeItem(item) => item,
1157 _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1160 let (generics, bounds) = match item.node {
1161 hir::ItemTrait(_, ref generics, ref supertraits, _) => (generics, supertraits),
1162 _ => tcx.sess.span_bug(item.span,
1163 "ensure_super_predicates_step invoked on non-trait"),
1166 // In-scope when converting the superbounds for `Trait` are
1167 // that `Self:Trait` as well as any bounds that appear on the
1169 let trait_def = trait_def_of_item(ccx, item);
1170 let self_predicate = ty::GenericPredicates {
1171 predicates: VecPerParamSpace::new(vec![],
1172 vec![trait_def.trait_ref.to_predicate()],
1175 let scope = &(generics, &self_predicate);
1177 // Convert the bounds that follow the colon, e.g. `Bar+Zed` in `trait Foo : Bar+Zed`.
1178 let self_param_ty = tcx.mk_self_type();
1179 let superbounds1 = compute_bounds(&ccx.icx(scope),
1185 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1187 // Convert any explicit superbounds in the where clause,
1188 // e.g. `trait Foo where Self : Bar`:
1189 let superbounds2 = generics.get_type_parameter_bounds(&ccx.icx(scope), item.span, item.id);
1191 // Combine the two lists to form the complete set of superbounds:
1192 let superbounds = superbounds1.into_iter().chain(superbounds2).collect();
1193 let superpredicates = ty::GenericPredicates {
1194 predicates: VecPerParamSpace::new(superbounds, vec![], vec![])
1196 debug!("superpredicates for trait {:?} = {:?}",
1197 tcx.map.local_def_id(item.id),
1200 tcx.super_predicates.borrow_mut().insert(trait_def_id, superpredicates.clone());
1205 let def_ids: Vec<_> = superpredicates.predicates
1207 .filter_map(|p| p.to_opt_poly_trait_ref())
1208 .map(|tr| tr.def_id())
1211 debug!("ensure_super_predicates_step: def_ids={:?}", def_ids);
1216 fn trait_def_of_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1218 -> &'tcx ty::TraitDef<'tcx>
1220 let def_id = ccx.tcx.map.local_def_id(it.id);
1223 if let Some(def) = tcx.trait_defs.borrow().get(&def_id) {
1227 let (unsafety, generics, items) = match it.node {
1228 hir::ItemTrait(unsafety, ref generics, _, ref items) => (unsafety, generics, items),
1229 _ => tcx.sess.span_bug(it.span, "trait_def_of_item invoked on non-trait"),
1232 let paren_sugar = tcx.has_attr(def_id, "rustc_paren_sugar");
1233 if paren_sugar && !ccx.tcx.sess.features.borrow().unboxed_closures {
1234 let mut err = ccx.tcx.sess.struct_span_err(
1236 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1237 which traits can use parenthetical notation");
1238 fileline_help!(&mut err, it.span,
1239 "add `#![feature(unboxed_closures)]` to \
1240 the crate attributes to use it");
1244 let substs = ccx.tcx.mk_substs(mk_trait_substs(ccx, generics));
1246 let ty_generics = ty_generics_for_trait(ccx, it.id, substs, generics);
1248 let associated_type_names: Vec<_> = items.iter().filter_map(|trait_item| {
1249 match trait_item.node {
1250 hir::TypeTraitItem(..) => Some(trait_item.name),
1255 let trait_ref = ty::TraitRef {
1260 let trait_def = ty::TraitDef::new(unsafety,
1264 associated_type_names);
1266 return tcx.intern_trait_def(trait_def);
1268 fn mk_trait_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1269 generics: &hir::Generics)
1274 // Creates a no-op substitution for the trait's type parameters.
1279 .map(|(i, def)| ty::ReEarlyBound(ty::EarlyBoundRegion {
1282 name: def.lifetime.name
1286 // Start with the generics in the type parameters...
1291 .map(|(i, def)| tcx.mk_param(TypeSpace,
1292 i as u32, def.name))
1295 // ...and also create the `Self` parameter.
1296 let self_ty = tcx.mk_self_type();
1298 Substs::new_trait(types, regions, self_ty)
1302 fn trait_defines_associated_type_named(ccx: &CrateCtxt,
1303 trait_node_id: ast::NodeId,
1304 assoc_name: ast::Name)
1307 let item = match ccx.tcx.map.get(trait_node_id) {
1308 hir_map::NodeItem(item) => item,
1309 _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1312 let trait_items = match item.node {
1313 hir::ItemTrait(_, _, _, ref trait_items) => trait_items,
1314 _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not a trait", trait_node_id))
1317 trait_items.iter().any(|trait_item| {
1318 match trait_item.node {
1319 hir::TypeTraitItem(..) => trait_item.name == assoc_name,
1325 fn convert_trait_predicates<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>, it: &hir::Item) {
1327 let trait_def = trait_def_of_item(ccx, it);
1329 let def_id = ccx.tcx.map.local_def_id(it.id);
1331 let (generics, items) = match it.node {
1332 hir::ItemTrait(_, ref generics, _, ref items) => (generics, items),
1336 &format!("trait_def_of_item invoked on {:?}", s));
1340 let super_predicates = ccx.tcx.lookup_super_predicates(def_id);
1342 // `ty_generic_predicates` below will consider the bounds on the type
1343 // parameters (including `Self`) and the explicit where-clauses,
1344 // but to get the full set of predicates on a trait we need to add
1345 // in the supertrait bounds and anything declared on the
1346 // associated types.
1347 let mut base_predicates = super_predicates;
1349 // Add in a predicate that `Self:Trait` (where `Trait` is the
1350 // current trait). This is needed for builtin bounds.
1351 let self_predicate = trait_def.trait_ref.to_poly_trait_ref().to_predicate();
1352 base_predicates.predicates.push(SelfSpace, self_predicate);
1354 // add in the explicit where-clauses
1355 let mut trait_predicates =
1356 ty_generic_predicates(ccx, TypeSpace, generics, &base_predicates);
1358 let assoc_predicates = predicates_for_associated_types(ccx,
1361 trait_def.trait_ref,
1363 trait_predicates.predicates.extend(TypeSpace, assoc_predicates.into_iter());
1365 let prev_predicates = tcx.predicates.borrow_mut().insert(def_id, trait_predicates);
1366 assert!(prev_predicates.is_none());
1370 fn predicates_for_associated_types<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1371 ast_generics: &hir::Generics,
1372 trait_predicates: &ty::GenericPredicates<'tcx>,
1373 self_trait_ref: ty::TraitRef<'tcx>,
1374 trait_items: &[hir::TraitItem])
1375 -> Vec<ty::Predicate<'tcx>>
1377 trait_items.iter().flat_map(|trait_item| {
1378 let bounds = match trait_item.node {
1379 hir::TypeTraitItem(ref bounds, _) => bounds,
1381 return vec!().into_iter();
1385 let assoc_ty = ccx.tcx.mk_projection(self_trait_ref,
1388 let bounds = compute_bounds(&ccx.icx(&(ast_generics, trait_predicates)),
1391 SizedByDefault::Yes,
1394 bounds.predicates(ccx.tcx, assoc_ty).into_iter()
1399 fn type_scheme_of_def_id<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1401 -> ty::TypeScheme<'tcx>
1403 if let Some(node_id) = ccx.tcx.map.as_local_node_id(def_id) {
1404 match ccx.tcx.map.find(node_id) {
1405 Some(hir_map::NodeItem(item)) => {
1406 type_scheme_of_item(ccx, &*item)
1408 Some(hir_map::NodeForeignItem(foreign_item)) => {
1409 let abi = ccx.tcx.map.get_foreign_abi(node_id);
1410 type_scheme_of_foreign_item(ccx, &*foreign_item, abi)
1413 ccx.tcx.sess.bug(&format!("unexpected sort of node \
1414 in get_item_type_scheme(): {:?}",
1419 ccx.tcx.lookup_item_type(def_id)
1423 fn type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1425 -> ty::TypeScheme<'tcx>
1427 let item_def_id = ccx.tcx.map.local_def_id(item.id);
1428 ccx.tcx.tcache.memoize(item_def_id, || {
1429 // NB. Since the `memoized` function enters a new task, and we
1430 // are giving this task access to the item `item`, we must
1432 ccx.tcx.dep_graph.read(DepNode::Hir(item_def_id));
1433 compute_type_scheme_of_item(ccx, item)
1437 fn compute_type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1439 -> ty::TypeScheme<'tcx>
1443 hir::ItemStatic(ref t, _, _) | hir::ItemConst(ref t, _) => {
1444 let ty = ccx.icx(&()).to_ty(&ExplicitRscope, &**t);
1445 ty::TypeScheme { ty: ty, generics: ty::Generics::empty() }
1447 hir::ItemFn(ref decl, unsafety, _, abi, ref generics, _) => {
1448 let ty_generics = ty_generics_for_fn(ccx, generics, &ty::Generics::empty());
1449 let tofd = astconv::ty_of_bare_fn(&ccx.icx(generics), unsafety, abi, &**decl);
1450 let ty = tcx.mk_fn(Some(ccx.tcx.map.local_def_id(it.id)), tcx.mk_bare_fn(tofd));
1451 ty::TypeScheme { ty: ty, generics: ty_generics }
1453 hir::ItemTy(ref t, ref generics) => {
1454 let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1455 let ty = ccx.icx(generics).to_ty(&ExplicitRscope, &**t);
1456 ty::TypeScheme { ty: ty, generics: ty_generics }
1458 hir::ItemEnum(ref ei, ref generics) => {
1459 let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1460 let substs = mk_item_substs(ccx, &ty_generics);
1461 let def = convert_enum_def(tcx, it, ei);
1462 let t = tcx.mk_enum(def, tcx.mk_substs(substs));
1463 ty::TypeScheme { ty: t, generics: ty_generics }
1465 hir::ItemStruct(ref si, ref generics) => {
1466 let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1467 let substs = mk_item_substs(ccx, &ty_generics);
1468 let def = convert_struct_def(tcx, it, si);
1469 let t = tcx.mk_struct(def, tcx.mk_substs(substs));
1470 ty::TypeScheme { ty: t, generics: ty_generics }
1472 hir::ItemDefaultImpl(..) |
1473 hir::ItemTrait(..) |
1476 hir::ItemForeignMod(..) |
1477 hir::ItemExternCrate(..) |
1478 hir::ItemUse(..) => {
1481 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1487 fn convert_typed_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1489 -> (ty::TypeScheme<'tcx>, ty::GenericPredicates<'tcx>)
1493 let tag = type_scheme_of_item(ccx, it);
1494 let scheme = TypeScheme { generics: tag.generics, ty: tag.ty };
1495 let predicates = match it.node {
1496 hir::ItemStatic(..) | hir::ItemConst(..) => {
1497 ty::GenericPredicates::empty()
1499 hir::ItemFn(_, _, _, _, ref ast_generics, _) => {
1500 ty_generic_predicates_for_fn(ccx, ast_generics, &ty::GenericPredicates::empty())
1502 hir::ItemTy(_, ref generics) => {
1503 ty_generic_predicates_for_type_or_impl(ccx, generics)
1505 hir::ItemEnum(_, ref generics) => {
1506 ty_generic_predicates_for_type_or_impl(ccx, generics)
1508 hir::ItemStruct(_, ref generics) => {
1509 ty_generic_predicates_for_type_or_impl(ccx, generics)
1511 hir::ItemDefaultImpl(..) |
1512 hir::ItemTrait(..) |
1513 hir::ItemExternCrate(..) |
1517 hir::ItemForeignMod(..) => {
1520 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1525 let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1526 predicates.clone());
1527 assert!(prev_predicates.is_none());
1530 if tcx.has_attr(ccx.tcx.map.local_def_id(it.id), "rustc_object_lifetime_default") {
1531 let object_lifetime_default_reprs: String =
1532 scheme.generics.types.iter()
1533 .map(|t| match t.object_lifetime_default {
1534 ty::ObjectLifetimeDefault::Specific(r) => r.to_string(),
1535 d => format!("{:?}", d),
1537 .collect::<Vec<String>>()
1540 tcx.sess.span_err(it.span, &object_lifetime_default_reprs);
1543 return (scheme, predicates);
1546 fn type_scheme_of_foreign_item<'a, 'tcx>(
1547 ccx: &CrateCtxt<'a, 'tcx>,
1548 item: &hir::ForeignItem,
1550 -> ty::TypeScheme<'tcx>
1552 let item_def_id = ccx.tcx.map.local_def_id(item.id);
1553 ccx.tcx.tcache.memoize(item_def_id, || {
1554 // NB. Since the `memoized` function enters a new task, and we
1555 // are giving this task access to the item `item`, we must
1557 ccx.tcx.dep_graph.read(DepNode::Hir(item_def_id));
1558 compute_type_scheme_of_foreign_item(ccx, item, abi)
1562 fn compute_type_scheme_of_foreign_item<'a, 'tcx>(
1563 ccx: &CrateCtxt<'a, 'tcx>,
1564 it: &hir::ForeignItem,
1566 -> ty::TypeScheme<'tcx>
1569 hir::ForeignItemFn(ref fn_decl, ref generics) => {
1570 compute_type_scheme_of_foreign_fn_decl(ccx, fn_decl, generics, abi)
1572 hir::ForeignItemStatic(ref t, _) => {
1574 generics: ty::Generics::empty(),
1575 ty: ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, t)
1581 fn convert_foreign_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1582 it: &hir::ForeignItem)
1584 // For reasons I cannot fully articulate, I do so hate the AST
1585 // map, and I regard each time that I use it as a personal and
1586 // moral failing, but at the moment it seems like the only
1587 // convenient way to extract the ABI. - ndm
1589 let abi = tcx.map.get_foreign_abi(it.id);
1591 let scheme = type_scheme_of_foreign_item(ccx, it, abi);
1592 write_ty_to_tcx(ccx.tcx, it.id, scheme.ty);
1594 let predicates = match it.node {
1595 hir::ForeignItemFn(_, ref generics) => {
1596 ty_generic_predicates_for_fn(ccx, generics, &ty::GenericPredicates::empty())
1598 hir::ForeignItemStatic(..) => {
1599 ty::GenericPredicates::empty()
1603 let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1605 assert!(prev_predicates.is_none());
1608 fn ty_generics_for_type_or_impl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1609 generics: &hir::Generics)
1610 -> ty::Generics<'tcx> {
1611 ty_generics(ccx, TypeSpace, generics, &ty::Generics::empty())
1614 fn ty_generic_predicates_for_type_or_impl<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1615 generics: &hir::Generics)
1616 -> ty::GenericPredicates<'tcx>
1618 ty_generic_predicates(ccx, TypeSpace, generics, &ty::GenericPredicates::empty())
1621 fn ty_generics_for_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1622 trait_id: ast::NodeId,
1623 substs: &'tcx Substs<'tcx>,
1624 ast_generics: &hir::Generics)
1625 -> ty::Generics<'tcx>
1627 debug!("ty_generics_for_trait(trait_id={:?}, substs={:?})",
1628 ccx.tcx.map.local_def_id(trait_id), substs);
1630 let mut generics = ty_generics_for_type_or_impl(ccx, ast_generics);
1632 // Add in the self type parameter.
1634 // Something of a hack: use the node id for the trait, also as
1635 // the node id for the Self type parameter.
1636 let param_id = trait_id;
1638 let parent = ccx.tcx.map.get_parent(param_id);
1640 let def = ty::TypeParameterDef {
1643 name: special_idents::type_self.name,
1644 def_id: ccx.tcx.map.local_def_id(param_id),
1645 default_def_id: ccx.tcx.map.local_def_id(parent),
1647 object_lifetime_default: ty::ObjectLifetimeDefault::BaseDefault,
1650 ccx.tcx.ty_param_defs.borrow_mut().insert(param_id, def.clone());
1652 generics.types.push(SelfSpace, def);
1657 fn ty_generics_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1658 generics: &hir::Generics,
1659 base_generics: &ty::Generics<'tcx>)
1660 -> ty::Generics<'tcx>
1662 ty_generics(ccx, FnSpace, generics, base_generics)
1665 fn ty_generic_predicates_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1666 generics: &hir::Generics,
1667 base_predicates: &ty::GenericPredicates<'tcx>)
1668 -> ty::GenericPredicates<'tcx>
1670 ty_generic_predicates(ccx, FnSpace, generics, base_predicates)
1673 // Add the Sized bound, unless the type parameter is marked as `?Sized`.
1674 fn add_unsized_bound<'tcx>(astconv: &AstConv<'tcx>,
1675 bounds: &mut ty::BuiltinBounds,
1676 ast_bounds: &[hir::TyParamBound],
1679 let tcx = astconv.tcx();
1681 // Try to find an unbound in bounds.
1682 let mut unbound = None;
1683 for ab in ast_bounds {
1684 if let &hir::TraitTyParamBound(ref ptr, hir::TraitBoundModifier::Maybe) = ab {
1685 if unbound.is_none() {
1686 assert!(ptr.bound_lifetimes.is_empty());
1687 unbound = Some(ptr.trait_ref.clone());
1689 span_err!(tcx.sess, span, E0203,
1690 "type parameter has more than one relaxed default \
1691 bound, only one is supported");
1696 let kind_id = tcx.lang_items.require(SizedTraitLangItem);
1699 // FIXME(#8559) currently requires the unbound to be built-in.
1700 let trait_def_id = tcx.trait_ref_to_def_id(tpb);
1702 Ok(kind_id) if trait_def_id != kind_id => {
1703 tcx.sess.span_warn(span,
1704 "default bound relaxed for a type parameter, but \
1705 this does nothing because the given bound is not \
1706 a default. Only `?Sized` is supported");
1707 tcx.try_add_builtin_trait(kind_id, bounds);
1712 _ if kind_id.is_ok() => {
1713 tcx.try_add_builtin_trait(kind_id.unwrap(), bounds);
1715 // No lang item for Sized, so we can't add it as a bound.
1720 /// Returns the early-bound lifetimes declared in this generics
1721 /// listing. For anything other than fns/methods, this is just all
1722 /// the lifetimes that are declared. For fns or methods, we have to
1723 /// screen out those that do not appear in any where-clauses etc using
1724 /// `resolve_lifetime::early_bound_lifetimes`.
1725 fn early_bound_lifetimes_from_generics(space: ParamSpace,
1726 ast_generics: &hir::Generics)
1727 -> Vec<hir::LifetimeDef>
1730 SelfSpace | TypeSpace => ast_generics.lifetimes.to_vec(),
1731 FnSpace => resolve_lifetime::early_bound_lifetimes(ast_generics),
1735 fn ty_generic_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1737 ast_generics: &hir::Generics,
1738 base_predicates: &ty::GenericPredicates<'tcx>)
1739 -> ty::GenericPredicates<'tcx>
1742 let mut result = base_predicates.clone();
1744 // Collect the predicates that were written inline by the user on each
1745 // type parameter (e.g., `<T:Foo>`).
1746 for (index, param) in ast_generics.ty_params.iter().enumerate() {
1747 let index = index as u32;
1748 let param_ty = ty::ParamTy::new(space, index, param.name).to_ty(ccx.tcx);
1749 let bounds = compute_bounds(&ccx.icx(&(base_predicates, ast_generics)),
1752 SizedByDefault::Yes,
1754 let predicates = bounds.predicates(ccx.tcx, param_ty);
1755 result.predicates.extend(space, predicates.into_iter());
1758 // Collect the region predicates that were declared inline as
1759 // well. In the case of parameters declared on a fn or method, we
1760 // have to be careful to only iterate over early-bound regions.
1761 let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1762 for (index, param) in early_lifetimes.iter().enumerate() {
1763 let index = index as u32;
1765 ty::ReEarlyBound(ty::EarlyBoundRegion {
1768 name: param.lifetime.name
1770 for bound in ¶m.bounds {
1771 let bound_region = ast_region_to_region(ccx.tcx, bound);
1772 let outlives = ty::Binder(ty::OutlivesPredicate(region, bound_region));
1773 result.predicates.push(space, outlives.to_predicate());
1777 // Add in the bounds that appear in the where-clause
1778 let where_clause = &ast_generics.where_clause;
1779 for predicate in &where_clause.predicates {
1781 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
1782 let ty = ast_ty_to_ty(&ccx.icx(&(base_predicates, ast_generics)),
1784 &*bound_pred.bounded_ty);
1786 for bound in bound_pred.bounds.iter() {
1788 &hir::TyParamBound::TraitTyParamBound(ref poly_trait_ref, _) => {
1789 let mut projections = Vec::new();
1792 conv_poly_trait_ref(&ccx.icx(&(base_predicates, ast_generics)),
1797 result.predicates.push(space, trait_ref.to_predicate());
1799 for projection in &projections {
1800 result.predicates.push(space, projection.to_predicate());
1804 &hir::TyParamBound::RegionTyParamBound(ref lifetime) => {
1805 let region = ast_region_to_region(tcx, lifetime);
1806 let pred = ty::Binder(ty::OutlivesPredicate(ty, region));
1807 result.predicates.push(space, ty::Predicate::TypeOutlives(pred))
1813 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
1814 let r1 = ast_region_to_region(tcx, ®ion_pred.lifetime);
1815 for bound in ®ion_pred.bounds {
1816 let r2 = ast_region_to_region(tcx, bound);
1817 let pred = ty::Binder(ty::OutlivesPredicate(r1, r2));
1818 result.predicates.push(space, ty::Predicate::RegionOutlives(pred))
1822 &hir::WherePredicate::EqPredicate(ref eq_pred) => {
1824 tcx.sess.span_bug(eq_pred.span,
1825 "Equality constraints are not yet \
1826 implemented (#20041)")
1834 fn ty_generics<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1836 ast_generics: &hir::Generics,
1837 base_generics: &ty::Generics<'tcx>)
1838 -> ty::Generics<'tcx>
1841 let mut result = base_generics.clone();
1843 let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1844 for (i, l) in early_lifetimes.iter().enumerate() {
1845 let bounds = l.bounds.iter()
1846 .map(|l| ast_region_to_region(tcx, l))
1848 let def = ty::RegionParameterDef { name: l.lifetime.name,
1851 def_id: ccx.tcx.map.local_def_id(l.lifetime.id),
1853 result.regions.push(space, def);
1856 assert!(result.types.is_empty_in(space));
1858 // Now create the real type parameters.
1859 for i in 0..ast_generics.ty_params.len() {
1860 let def = get_or_create_type_parameter_def(ccx, ast_generics, space, i as u32);
1861 debug!("ty_generics: def for type param: {:?}, {:?}", def, space);
1862 result.types.push(space, def);
1868 fn convert_default_type_parameter<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1874 let ty = ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, &path);
1876 for leaf_ty in ty.walk() {
1877 if let ty::TyParam(p) = leaf_ty.sty {
1878 if p.space == space && p.idx >= index {
1879 span_err!(ccx.tcx.sess, path.span, E0128,
1880 "type parameters with a default cannot use \
1881 forward declared identifiers");
1883 return ccx.tcx.types.err
1891 fn get_or_create_type_parameter_def<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1892 ast_generics: &hir::Generics,
1895 -> ty::TypeParameterDef<'tcx>
1897 let param = &ast_generics.ty_params[index as usize];
1900 match tcx.ty_param_defs.borrow().get(¶m.id) {
1901 Some(d) => { return d.clone(); }
1905 let default = param.default.as_ref().map(
1906 |def| convert_default_type_parameter(ccx, def, space, index)
1909 let object_lifetime_default =
1910 compute_object_lifetime_default(ccx, param.id,
1911 ¶m.bounds, &ast_generics.where_clause);
1913 let parent = tcx.map.get_parent(param.id);
1915 if space != TypeSpace && default.is_some() {
1916 if !tcx.sess.features.borrow().default_type_parameter_fallback {
1918 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1921 format!("defaults for type parameters are only allowed on type definitions, \
1922 like `struct` or `enum`"));
1926 let def = ty::TypeParameterDef {
1930 def_id: ccx.tcx.map.local_def_id(param.id),
1931 default_def_id: ccx.tcx.map.local_def_id(parent),
1933 object_lifetime_default: object_lifetime_default,
1936 tcx.ty_param_defs.borrow_mut().insert(param.id, def.clone());
1941 /// Scan the bounds and where-clauses on a parameter to extract bounds
1942 /// of the form `T:'a` so as to determine the `ObjectLifetimeDefault`.
1943 /// This runs as part of computing the minimal type scheme, so we
1944 /// intentionally avoid just asking astconv to convert all the where
1945 /// clauses into a `ty::Predicate`. This is because that could induce
1946 /// artificial cycles.
1947 fn compute_object_lifetime_default<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1948 param_id: ast::NodeId,
1949 param_bounds: &[hir::TyParamBound],
1950 where_clause: &hir::WhereClause)
1951 -> ty::ObjectLifetimeDefault
1953 let inline_bounds = from_bounds(ccx, param_bounds);
1954 let where_bounds = from_predicates(ccx, param_id, &where_clause.predicates);
1955 let all_bounds: HashSet<_> = inline_bounds.into_iter()
1956 .chain(where_bounds)
1958 return if all_bounds.len() > 1 {
1959 ty::ObjectLifetimeDefault::Ambiguous
1960 } else if all_bounds.len() == 0 {
1961 ty::ObjectLifetimeDefault::BaseDefault
1963 ty::ObjectLifetimeDefault::Specific(
1964 all_bounds.into_iter().next().unwrap())
1967 fn from_bounds<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1968 bounds: &[hir::TyParamBound])
1972 .filter_map(|bound| {
1974 hir::TraitTyParamBound(..) =>
1976 hir::RegionTyParamBound(ref lifetime) =>
1977 Some(astconv::ast_region_to_region(ccx.tcx, lifetime)),
1983 fn from_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1984 param_id: ast::NodeId,
1985 predicates: &[hir::WherePredicate])
1989 .flat_map(|predicate| {
1991 hir::WherePredicate::BoundPredicate(ref data) => {
1992 if data.bound_lifetimes.is_empty() &&
1993 is_param(ccx.tcx, &data.bounded_ty, param_id)
1995 from_bounds(ccx, &data.bounds).into_iter()
1997 Vec::new().into_iter()
2000 hir::WherePredicate::RegionPredicate(..) |
2001 hir::WherePredicate::EqPredicate(..) => {
2002 Vec::new().into_iter()
2010 enum SizedByDefault { Yes, No, }
2012 /// Translate the AST's notion of ty param bounds (which are an enum consisting of a newtyped Ty or
2013 /// a region) to ty's notion of ty param bounds, which can either be user-defined traits, or the
2014 /// built-in trait (formerly known as kind): Send.
2015 fn compute_bounds<'tcx>(astconv: &AstConv<'tcx>,
2016 param_ty: ty::Ty<'tcx>,
2017 ast_bounds: &[hir::TyParamBound],
2018 sized_by_default: SizedByDefault,
2020 -> astconv::Bounds<'tcx>
2023 conv_param_bounds(astconv,
2028 if let SizedByDefault::Yes = sized_by_default {
2029 add_unsized_bound(astconv,
2030 &mut bounds.builtin_bounds,
2035 bounds.trait_bounds.sort_by(|a,b| a.def_id().cmp(&b.def_id()));
2040 /// Converts a specific TyParamBound from the AST into a set of
2041 /// predicates that apply to the self-type. A vector is returned
2042 /// because this can be anywhere from 0 predicates (`T:?Sized` adds no
2043 /// predicates) to 1 (`T:Foo`) to many (`T:Bar<X=i32>` adds `T:Bar`
2044 /// and `<T as Bar>::X == i32`).
2045 fn predicates_from_bound<'tcx>(astconv: &AstConv<'tcx>,
2047 bound: &hir::TyParamBound)
2048 -> Vec<ty::Predicate<'tcx>>
2051 hir::TraitTyParamBound(ref tr, hir::TraitBoundModifier::None) => {
2052 let mut projections = Vec::new();
2053 let pred = conv_poly_trait_ref(astconv, param_ty, tr, &mut projections);
2054 projections.into_iter()
2055 .map(|p| p.to_predicate())
2056 .chain(Some(pred.to_predicate()))
2059 hir::RegionTyParamBound(ref lifetime) => {
2060 let region = ast_region_to_region(astconv.tcx(), lifetime);
2061 let pred = ty::Binder(ty::OutlivesPredicate(param_ty, region));
2062 vec![ty::Predicate::TypeOutlives(pred)]
2064 hir::TraitTyParamBound(_, hir::TraitBoundModifier::Maybe) => {
2070 fn conv_poly_trait_ref<'tcx>(astconv: &AstConv<'tcx>,
2072 trait_ref: &hir::PolyTraitRef,
2073 projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
2074 -> ty::PolyTraitRef<'tcx>
2076 astconv::instantiate_poly_trait_ref(astconv,
2083 fn conv_param_bounds<'a,'tcx>(astconv: &AstConv<'tcx>,
2085 param_ty: ty::Ty<'tcx>,
2086 ast_bounds: &[hir::TyParamBound])
2087 -> astconv::Bounds<'tcx>
2089 let tcx = astconv.tcx();
2090 let astconv::PartitionedBounds {
2094 } = astconv::partition_bounds(tcx, span, &ast_bounds);
2096 let mut projection_bounds = Vec::new();
2098 let trait_bounds: Vec<ty::PolyTraitRef> =
2100 .map(|bound| conv_poly_trait_ref(astconv,
2103 &mut projection_bounds))
2106 let region_bounds: Vec<ty::Region> =
2107 region_bounds.into_iter()
2108 .map(|r| ast_region_to_region(tcx, r))
2112 region_bounds: region_bounds,
2113 builtin_bounds: builtin_bounds,
2114 trait_bounds: trait_bounds,
2115 projection_bounds: projection_bounds,
2119 fn compute_type_scheme_of_foreign_fn_decl<'a, 'tcx>(
2120 ccx: &CrateCtxt<'a, 'tcx>,
2122 ast_generics: &hir::Generics,
2124 -> ty::TypeScheme<'tcx>
2126 for i in &decl.inputs {
2127 match (*i).pat.node {
2128 hir::PatIdent(_, _, _) => (),
2131 span_err!(ccx.tcx.sess, (*i).pat.span, E0130,
2132 "patterns aren't allowed in foreign function declarations");
2137 let ty_generics = ty_generics_for_fn(ccx, ast_generics, &ty::Generics::empty());
2139 let rb = BindingRscope::new();
2140 let input_tys = decl.inputs
2142 .map(|a| ty_of_arg(&ccx.icx(ast_generics), &rb, a, None))
2145 let output = match decl.output {
2146 hir::Return(ref ty) =>
2147 ty::FnConverging(ast_ty_to_ty(&ccx.icx(ast_generics), &rb, &**ty)),
2148 hir::DefaultReturn(..) =>
2149 ty::FnConverging(ccx.tcx.mk_nil()),
2150 hir::NoReturn(..) =>
2154 let t_fn = ccx.tcx.mk_fn(None,
2155 ccx.tcx.mk_bare_fn(ty::BareFnTy {
2157 unsafety: hir::Unsafety::Unsafe,
2158 sig: ty::Binder(ty::FnSig {inputs: input_tys,
2160 variadic: decl.variadic}),
2164 generics: ty_generics,
2169 fn mk_item_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
2170 ty_generics: &ty::Generics<'tcx>)
2174 ty_generics.types.map(
2175 |def| ccx.tcx.mk_param_from_def(def));
2178 ty_generics.regions.map(
2179 |def| def.to_early_bound_region());
2181 Substs::new(types, regions)
2184 /// Checks that all the type parameters on an impl
2185 fn enforce_impl_params_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,
2186 ast_generics: &hir::Generics,
2187 impl_predicates: &mut ty::GenericPredicates<'tcx>,
2190 let impl_scheme = tcx.lookup_item_type(impl_def_id);
2191 let impl_trait_ref = tcx.impl_trait_ref(impl_def_id);
2193 assert!(impl_predicates.predicates.is_empty_in(FnSpace));
2194 assert!(impl_predicates.predicates.is_empty_in(SelfSpace));
2196 // The trait reference is an input, so find all type parameters
2197 // reachable from there, to start (if this is an inherent impl,
2198 // then just examine the self type).
2199 let mut input_parameters: HashSet<_> =
2200 ctp::parameters_for_type(impl_scheme.ty, false).into_iter().collect();
2201 if let Some(ref trait_ref) = impl_trait_ref {
2202 input_parameters.extend(ctp::parameters_for_trait_ref(trait_ref, false));
2205 ctp::setup_constraining_predicates(tcx,
2206 impl_predicates.predicates.get_mut_slice(TypeSpace),
2208 &mut input_parameters);
2210 for (index, ty_param) in ast_generics.ty_params.iter().enumerate() {
2211 let param_ty = ty::ParamTy { space: TypeSpace,
2213 name: ty_param.name };
2214 if !input_parameters.contains(&ctp::Parameter::Type(param_ty)) {
2215 report_unused_parameter(tcx, ty_param.span, "type", ¶m_ty.to_string());
2220 fn enforce_impl_lifetimes_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,
2221 ast_generics: &hir::Generics,
2223 impl_items: &[hir::ImplItem])
2225 // Every lifetime used in an associated type must be constrained.
2226 let impl_scheme = tcx.lookup_item_type(impl_def_id);
2227 let impl_predicates = tcx.lookup_predicates(impl_def_id);
2228 let impl_trait_ref = tcx.impl_trait_ref(impl_def_id);
2230 let mut input_parameters: HashSet<_> =
2231 ctp::parameters_for_type(impl_scheme.ty, false).into_iter().collect();
2232 if let Some(ref trait_ref) = impl_trait_ref {
2233 input_parameters.extend(ctp::parameters_for_trait_ref(trait_ref, false));
2235 ctp::identify_constrained_type_params(tcx,
2236 &impl_predicates.predicates.as_slice(), impl_trait_ref, &mut input_parameters);
2238 let lifetimes_in_associated_types: HashSet<_> =
2240 .map(|item| tcx.impl_or_trait_item(tcx.map.local_def_id(item.id)))
2241 .filter_map(|item| match item {
2242 ty::TypeTraitItem(ref assoc_ty) => assoc_ty.ty,
2243 ty::ConstTraitItem(..) | ty::MethodTraitItem(..) => None
2245 .flat_map(|ty| ctp::parameters_for_type(ty, true))
2246 .filter_map(|p| match p {
2247 ctp::Parameter::Type(_) => None,
2248 ctp::Parameter::Region(r) => Some(r),
2252 for (index, lifetime_def) in ast_generics.lifetimes.iter().enumerate() {
2253 let region = ty::EarlyBoundRegion { space: TypeSpace,
2254 index: index as u32,
2255 name: lifetime_def.lifetime.name };
2257 lifetimes_in_associated_types.contains(®ion) && // (*)
2258 !input_parameters.contains(&ctp::Parameter::Region(region))
2260 report_unused_parameter(tcx, lifetime_def.lifetime.span,
2261 "lifetime", ®ion.name.to_string());
2265 // (*) This is a horrible concession to reality. I think it'd be
2266 // better to just ban unconstrianed lifetimes outright, but in
2267 // practice people do non-hygenic macros like:
2270 // macro_rules! __impl_slice_eq1 {
2271 // ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
2272 // impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> {
2279 // In a concession to backwards compatbility, we continue to
2280 // permit those, so long as the lifetimes aren't used in
2281 // associated types. I believe this is sound, because lifetimes
2282 // used elsewhere are not projected back out.
2285 fn report_unused_parameter(tcx: &ty::ctxt,
2290 span_err!(tcx.sess, span, E0207,
2291 "the {} parameter `{}` is not constrained by the \
2292 impl trait, self type, or predicates",