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 {
1013 fn convert_struct_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1015 def: &hir::VariantData)
1016 -> ty::AdtDefMaster<'tcx>
1019 let did = tcx.map.local_def_id(it.id);
1020 let ctor_id = if !def.is_struct() {
1021 tcx.map.local_def_id(def.id())
1027 ty::AdtKind::Struct,
1028 vec![convert_struct_variant(tcx, ctor_id, it.name, 0, def)]
1032 fn convert_enum_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1035 -> ty::AdtDefMaster<'tcx>
1037 fn evaluate_disr_expr<'tcx>(tcx: &ty::ctxt<'tcx>,
1039 e: &hir::Expr) -> Option<ty::Disr> {
1040 debug!("disr expr, checking {}", pprust::expr_to_string(e));
1042 let hint = UncheckedExprHint(repr_ty);
1043 match const_eval::eval_const_expr_partial(tcx, e, hint, None) {
1044 Ok(ConstVal::Int(val)) => Some(val as ty::Disr),
1045 Ok(ConstVal::Uint(val)) => Some(val as ty::Disr),
1047 let sign_desc = if repr_ty.is_signed() {
1052 span_err!(tcx.sess, e.span, E0079,
1053 "expected {} integer constant",
1058 let mut diag = struct_span_err!(tcx.sess, err.span, E0080,
1059 "constant evaluation error: {}",
1061 if !e.span.contains(err.span) {
1062 diag.span_note(e.span, "for enum discriminant here");
1070 fn report_discrim_overflow(tcx: &ty::ctxt,
1073 repr_type: attr::IntType,
1074 prev_val: ty::Disr) {
1075 let computed_value = repr_type.disr_wrap_incr(Some(prev_val));
1076 let computed_value = repr_type.disr_string(computed_value);
1077 let prev_val = repr_type.disr_string(prev_val);
1078 let repr_type = repr_type.to_ty(tcx);
1079 span_err!(tcx.sess, variant_span, E0370,
1080 "enum discriminant overflowed on value after {}: {}; \
1081 set explicitly via {} = {} if that is desired outcome",
1082 prev_val, repr_type, variant_name, computed_value);
1085 fn next_disr(tcx: &ty::ctxt,
1087 repr_type: attr::IntType,
1088 prev_disr_val: Option<ty::Disr>) -> Option<ty::Disr> {
1089 if let Some(prev_disr_val) = prev_disr_val {
1090 let result = repr_type.disr_incr(prev_disr_val);
1091 if let None = result {
1092 report_discrim_overflow(tcx, v.span, &v.node.name.as_str(),
1093 repr_type, prev_disr_val);
1097 Some(ty::INITIAL_DISCRIMINANT_VALUE)
1100 fn convert_enum_variant<'tcx>(tcx: &ty::ctxt<'tcx>,
1103 -> ty::VariantDefData<'tcx, 'tcx>
1105 let did = tcx.map.local_def_id(v.node.data.id());
1106 let name = v.node.name;
1107 convert_struct_variant(tcx, did, name, disr, &v.node.data)
1109 let did = tcx.map.local_def_id(it.id);
1110 let repr_hints = tcx.lookup_repr_hints(did);
1111 let (repr_type, repr_type_ty) = tcx.enum_repr_type(repr_hints.get(0));
1112 let mut prev_disr = None;
1113 let variants = def.variants.iter().map(|v| {
1114 let disr = match v.node.disr_expr {
1115 Some(ref e) => evaluate_disr_expr(tcx, repr_type_ty, e),
1116 None => next_disr(tcx, v, repr_type, prev_disr)
1117 }.unwrap_or(repr_type.disr_wrap_incr(prev_disr));
1119 let v = convert_enum_variant(tcx, v, disr);
1120 prev_disr = Some(disr);
1123 tcx.intern_adt_def(tcx.map.local_def_id(it.id), ty::AdtKind::Enum, variants)
1126 /// Ensures that the super-predicates of the trait with def-id
1127 /// trait_def_id are converted and stored. This does NOT ensure that
1128 /// the transitive super-predicates are converted; that is the job of
1129 /// the `ensure_super_predicates()` method in the `AstConv` impl
1130 /// above. Returns a list of trait def-ids that must be ensured as
1131 /// well to guarantee that the transitive superpredicates are
1133 fn ensure_super_predicates_step(ccx: &CrateCtxt,
1134 trait_def_id: DefId)
1139 debug!("ensure_super_predicates_step(trait_def_id={:?})", trait_def_id);
1141 let trait_node_id = if let Some(n) = tcx.map.as_local_node_id(trait_def_id) {
1144 // If this trait comes from an external crate, then all of the
1145 // supertraits it may depend on also must come from external
1146 // crates, and hence all of them already have their
1147 // super-predicates "converted" (and available from crate
1148 // meta-data), so there is no need to transitively test them.
1152 let superpredicates = tcx.super_predicates.borrow().get(&trait_def_id).cloned();
1153 let superpredicates = superpredicates.unwrap_or_else(|| {
1154 let item = match ccx.tcx.map.get(trait_node_id) {
1155 hir_map::NodeItem(item) => item,
1156 _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1159 let (generics, bounds) = match item.node {
1160 hir::ItemTrait(_, ref generics, ref supertraits, _) => (generics, supertraits),
1161 _ => tcx.sess.span_bug(item.span,
1162 "ensure_super_predicates_step invoked on non-trait"),
1165 // In-scope when converting the superbounds for `Trait` are
1166 // that `Self:Trait` as well as any bounds that appear on the
1168 let trait_def = trait_def_of_item(ccx, item);
1169 let self_predicate = ty::GenericPredicates {
1170 predicates: VecPerParamSpace::new(vec![],
1171 vec![trait_def.trait_ref.to_predicate()],
1174 let scope = &(generics, &self_predicate);
1176 // Convert the bounds that follow the colon, e.g. `Bar+Zed` in `trait Foo : Bar+Zed`.
1177 let self_param_ty = tcx.mk_self_type();
1178 let superbounds1 = compute_bounds(&ccx.icx(scope),
1184 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1186 // Convert any explicit superbounds in the where clause,
1187 // e.g. `trait Foo where Self : Bar`:
1188 let superbounds2 = generics.get_type_parameter_bounds(&ccx.icx(scope), item.span, item.id);
1190 // Combine the two lists to form the complete set of superbounds:
1191 let superbounds = superbounds1.into_iter().chain(superbounds2).collect();
1192 let superpredicates = ty::GenericPredicates {
1193 predicates: VecPerParamSpace::new(superbounds, vec![], vec![])
1195 debug!("superpredicates for trait {:?} = {:?}",
1196 tcx.map.local_def_id(item.id),
1199 tcx.super_predicates.borrow_mut().insert(trait_def_id, superpredicates.clone());
1204 let def_ids: Vec<_> = superpredicates.predicates
1206 .filter_map(|p| p.to_opt_poly_trait_ref())
1207 .map(|tr| tr.def_id())
1210 debug!("ensure_super_predicates_step: def_ids={:?}", def_ids);
1215 fn trait_def_of_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1217 -> &'tcx ty::TraitDef<'tcx>
1219 let def_id = ccx.tcx.map.local_def_id(it.id);
1222 if let Some(def) = tcx.trait_defs.borrow().get(&def_id) {
1226 let (unsafety, generics, items) = match it.node {
1227 hir::ItemTrait(unsafety, ref generics, _, ref items) => (unsafety, generics, items),
1228 _ => tcx.sess.span_bug(it.span, "trait_def_of_item invoked on non-trait"),
1231 let paren_sugar = tcx.has_attr(def_id, "rustc_paren_sugar");
1232 if paren_sugar && !ccx.tcx.sess.features.borrow().unboxed_closures {
1233 let mut err = ccx.tcx.sess.struct_span_err(
1235 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1236 which traits can use parenthetical notation");
1237 fileline_help!(&mut err, it.span,
1238 "add `#![feature(unboxed_closures)]` to \
1239 the crate attributes to use it");
1243 let substs = ccx.tcx.mk_substs(mk_trait_substs(ccx, generics));
1245 let ty_generics = ty_generics_for_trait(ccx, it.id, substs, generics);
1247 let associated_type_names: Vec<_> = items.iter().filter_map(|trait_item| {
1248 match trait_item.node {
1249 hir::TypeTraitItem(..) => Some(trait_item.name),
1254 let trait_ref = ty::TraitRef {
1259 let trait_def = ty::TraitDef::new(unsafety,
1263 associated_type_names);
1265 return tcx.intern_trait_def(trait_def);
1267 fn mk_trait_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1268 generics: &hir::Generics)
1273 // Creates a no-op substitution for the trait's type parameters.
1278 .map(|(i, def)| ty::ReEarlyBound(ty::EarlyBoundRegion {
1281 name: def.lifetime.name
1285 // Start with the generics in the type parameters...
1290 .map(|(i, def)| tcx.mk_param(TypeSpace,
1291 i as u32, def.name))
1294 // ...and also create the `Self` parameter.
1295 let self_ty = tcx.mk_self_type();
1297 Substs::new_trait(types, regions, self_ty)
1301 fn trait_defines_associated_type_named(ccx: &CrateCtxt,
1302 trait_node_id: ast::NodeId,
1303 assoc_name: ast::Name)
1306 let item = match ccx.tcx.map.get(trait_node_id) {
1307 hir_map::NodeItem(item) => item,
1308 _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1311 let trait_items = match item.node {
1312 hir::ItemTrait(_, _, _, ref trait_items) => trait_items,
1313 _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not a trait", trait_node_id))
1316 trait_items.iter().any(|trait_item| {
1317 match trait_item.node {
1318 hir::TypeTraitItem(..) => trait_item.name == assoc_name,
1324 fn convert_trait_predicates<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>, it: &hir::Item) {
1326 let trait_def = trait_def_of_item(ccx, it);
1328 let def_id = ccx.tcx.map.local_def_id(it.id);
1330 let (generics, items) = match it.node {
1331 hir::ItemTrait(_, ref generics, _, ref items) => (generics, items),
1335 &format!("trait_def_of_item invoked on {:?}", s));
1339 let super_predicates = ccx.tcx.lookup_super_predicates(def_id);
1341 // `ty_generic_predicates` below will consider the bounds on the type
1342 // parameters (including `Self`) and the explicit where-clauses,
1343 // but to get the full set of predicates on a trait we need to add
1344 // in the supertrait bounds and anything declared on the
1345 // associated types.
1346 let mut base_predicates = super_predicates;
1348 // Add in a predicate that `Self:Trait` (where `Trait` is the
1349 // current trait). This is needed for builtin bounds.
1350 let self_predicate = trait_def.trait_ref.to_poly_trait_ref().to_predicate();
1351 base_predicates.predicates.push(SelfSpace, self_predicate);
1353 // add in the explicit where-clauses
1354 let mut trait_predicates =
1355 ty_generic_predicates(ccx, TypeSpace, generics, &base_predicates);
1357 let assoc_predicates = predicates_for_associated_types(ccx,
1360 trait_def.trait_ref,
1362 trait_predicates.predicates.extend(TypeSpace, assoc_predicates.into_iter());
1364 let prev_predicates = tcx.predicates.borrow_mut().insert(def_id, trait_predicates);
1365 assert!(prev_predicates.is_none());
1369 fn predicates_for_associated_types<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1370 ast_generics: &hir::Generics,
1371 trait_predicates: &ty::GenericPredicates<'tcx>,
1372 self_trait_ref: ty::TraitRef<'tcx>,
1373 trait_items: &[hir::TraitItem])
1374 -> Vec<ty::Predicate<'tcx>>
1376 trait_items.iter().flat_map(|trait_item| {
1377 let bounds = match trait_item.node {
1378 hir::TypeTraitItem(ref bounds, _) => bounds,
1380 return vec!().into_iter();
1384 let assoc_ty = ccx.tcx.mk_projection(self_trait_ref,
1387 let bounds = compute_bounds(&ccx.icx(&(ast_generics, trait_predicates)),
1390 SizedByDefault::Yes,
1393 bounds.predicates(ccx.tcx, assoc_ty).into_iter()
1398 fn type_scheme_of_def_id<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1400 -> ty::TypeScheme<'tcx>
1402 if let Some(node_id) = ccx.tcx.map.as_local_node_id(def_id) {
1403 match ccx.tcx.map.find(node_id) {
1404 Some(hir_map::NodeItem(item)) => {
1405 type_scheme_of_item(ccx, &*item)
1407 Some(hir_map::NodeForeignItem(foreign_item)) => {
1408 let abi = ccx.tcx.map.get_foreign_abi(node_id);
1409 type_scheme_of_foreign_item(ccx, &*foreign_item, abi)
1412 ccx.tcx.sess.bug(&format!("unexpected sort of node \
1413 in get_item_type_scheme(): {:?}",
1418 ccx.tcx.lookup_item_type(def_id)
1422 fn type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1424 -> ty::TypeScheme<'tcx>
1426 let item_def_id = ccx.tcx.map.local_def_id(item.id);
1427 ccx.tcx.tcache.memoize(item_def_id, || {
1428 // NB. Since the `memoized` function enters a new task, and we
1429 // are giving this task access to the item `item`, we must
1431 ccx.tcx.dep_graph.read(DepNode::Hir(item_def_id));
1432 compute_type_scheme_of_item(ccx, item)
1436 fn compute_type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1438 -> ty::TypeScheme<'tcx>
1442 hir::ItemStatic(ref t, _, _) | hir::ItemConst(ref t, _) => {
1443 let ty = ccx.icx(&()).to_ty(&ExplicitRscope, &**t);
1444 ty::TypeScheme { ty: ty, generics: ty::Generics::empty() }
1446 hir::ItemFn(ref decl, unsafety, _, abi, ref generics, _) => {
1447 let ty_generics = ty_generics_for_fn(ccx, generics, &ty::Generics::empty());
1448 let tofd = astconv::ty_of_bare_fn(&ccx.icx(generics), unsafety, abi, &**decl);
1449 let ty = tcx.mk_fn(Some(ccx.tcx.map.local_def_id(it.id)), tcx.mk_bare_fn(tofd));
1450 ty::TypeScheme { ty: ty, generics: ty_generics }
1452 hir::ItemTy(ref t, ref generics) => {
1453 let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1454 let ty = ccx.icx(generics).to_ty(&ExplicitRscope, &**t);
1455 ty::TypeScheme { ty: ty, generics: ty_generics }
1457 hir::ItemEnum(ref ei, ref generics) => {
1458 let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1459 let substs = mk_item_substs(ccx, &ty_generics);
1460 let def = convert_enum_def(tcx, it, ei);
1461 let t = tcx.mk_enum(def, tcx.mk_substs(substs));
1462 ty::TypeScheme { ty: t, generics: ty_generics }
1464 hir::ItemStruct(ref si, ref generics) => {
1465 let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1466 let substs = mk_item_substs(ccx, &ty_generics);
1467 let def = convert_struct_def(tcx, it, si);
1468 let t = tcx.mk_struct(def, tcx.mk_substs(substs));
1469 ty::TypeScheme { ty: t, generics: ty_generics }
1471 hir::ItemDefaultImpl(..) |
1472 hir::ItemTrait(..) |
1475 hir::ItemForeignMod(..) |
1476 hir::ItemExternCrate(..) |
1477 hir::ItemUse(..) => {
1480 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1486 fn convert_typed_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1488 -> (ty::TypeScheme<'tcx>, ty::GenericPredicates<'tcx>)
1492 let tag = type_scheme_of_item(ccx, it);
1493 let scheme = TypeScheme { generics: tag.generics, ty: tag.ty };
1494 let predicates = match it.node {
1495 hir::ItemStatic(..) | hir::ItemConst(..) => {
1496 ty::GenericPredicates::empty()
1498 hir::ItemFn(_, _, _, _, ref ast_generics, _) => {
1499 ty_generic_predicates_for_fn(ccx, ast_generics, &ty::GenericPredicates::empty())
1501 hir::ItemTy(_, ref generics) => {
1502 ty_generic_predicates_for_type_or_impl(ccx, generics)
1504 hir::ItemEnum(_, ref generics) => {
1505 ty_generic_predicates_for_type_or_impl(ccx, generics)
1507 hir::ItemStruct(_, ref generics) => {
1508 ty_generic_predicates_for_type_or_impl(ccx, generics)
1510 hir::ItemDefaultImpl(..) |
1511 hir::ItemTrait(..) |
1512 hir::ItemExternCrate(..) |
1516 hir::ItemForeignMod(..) => {
1519 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1524 let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1525 predicates.clone());
1526 assert!(prev_predicates.is_none());
1529 if tcx.has_attr(ccx.tcx.map.local_def_id(it.id), "rustc_object_lifetime_default") {
1530 let object_lifetime_default_reprs: String =
1531 scheme.generics.types.iter()
1532 .map(|t| match t.object_lifetime_default {
1533 ty::ObjectLifetimeDefault::Specific(r) => r.to_string(),
1534 d => format!("{:?}", d),
1536 .collect::<Vec<String>>()
1539 tcx.sess.span_err(it.span, &object_lifetime_default_reprs);
1542 return (scheme, predicates);
1545 fn type_scheme_of_foreign_item<'a, 'tcx>(
1546 ccx: &CrateCtxt<'a, 'tcx>,
1547 item: &hir::ForeignItem,
1549 -> ty::TypeScheme<'tcx>
1551 let item_def_id = ccx.tcx.map.local_def_id(item.id);
1552 ccx.tcx.tcache.memoize(item_def_id, || {
1553 // NB. Since the `memoized` function enters a new task, and we
1554 // are giving this task access to the item `item`, we must
1556 ccx.tcx.dep_graph.read(DepNode::Hir(item_def_id));
1557 compute_type_scheme_of_foreign_item(ccx, item, abi)
1561 fn compute_type_scheme_of_foreign_item<'a, 'tcx>(
1562 ccx: &CrateCtxt<'a, 'tcx>,
1563 it: &hir::ForeignItem,
1565 -> ty::TypeScheme<'tcx>
1568 hir::ForeignItemFn(ref fn_decl, ref generics) => {
1569 compute_type_scheme_of_foreign_fn_decl(ccx, fn_decl, generics, abi)
1571 hir::ForeignItemStatic(ref t, _) => {
1573 generics: ty::Generics::empty(),
1574 ty: ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, t)
1580 fn convert_foreign_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1581 it: &hir::ForeignItem)
1583 // For reasons I cannot fully articulate, I do so hate the AST
1584 // map, and I regard each time that I use it as a personal and
1585 // moral failing, but at the moment it seems like the only
1586 // convenient way to extract the ABI. - ndm
1588 let abi = tcx.map.get_foreign_abi(it.id);
1590 let scheme = type_scheme_of_foreign_item(ccx, it, abi);
1591 write_ty_to_tcx(ccx.tcx, it.id, scheme.ty);
1593 let predicates = match it.node {
1594 hir::ForeignItemFn(_, ref generics) => {
1595 ty_generic_predicates_for_fn(ccx, generics, &ty::GenericPredicates::empty())
1597 hir::ForeignItemStatic(..) => {
1598 ty::GenericPredicates::empty()
1602 let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1604 assert!(prev_predicates.is_none());
1607 fn ty_generics_for_type_or_impl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1608 generics: &hir::Generics)
1609 -> ty::Generics<'tcx> {
1610 ty_generics(ccx, TypeSpace, generics, &ty::Generics::empty())
1613 fn ty_generic_predicates_for_type_or_impl<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1614 generics: &hir::Generics)
1615 -> ty::GenericPredicates<'tcx>
1617 ty_generic_predicates(ccx, TypeSpace, generics, &ty::GenericPredicates::empty())
1620 fn ty_generics_for_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1621 trait_id: ast::NodeId,
1622 substs: &'tcx Substs<'tcx>,
1623 ast_generics: &hir::Generics)
1624 -> ty::Generics<'tcx>
1626 debug!("ty_generics_for_trait(trait_id={:?}, substs={:?})",
1627 ccx.tcx.map.local_def_id(trait_id), substs);
1629 let mut generics = ty_generics_for_type_or_impl(ccx, ast_generics);
1631 // Add in the self type parameter.
1633 // Something of a hack: use the node id for the trait, also as
1634 // the node id for the Self type parameter.
1635 let param_id = trait_id;
1637 let parent = ccx.tcx.map.get_parent(param_id);
1639 let def = ty::TypeParameterDef {
1642 name: special_idents::type_self.name,
1643 def_id: ccx.tcx.map.local_def_id(param_id),
1644 default_def_id: ccx.tcx.map.local_def_id(parent),
1646 object_lifetime_default: ty::ObjectLifetimeDefault::BaseDefault,
1649 ccx.tcx.ty_param_defs.borrow_mut().insert(param_id, def.clone());
1651 generics.types.push(SelfSpace, def);
1656 fn ty_generics_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1657 generics: &hir::Generics,
1658 base_generics: &ty::Generics<'tcx>)
1659 -> ty::Generics<'tcx>
1661 ty_generics(ccx, FnSpace, generics, base_generics)
1664 fn ty_generic_predicates_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1665 generics: &hir::Generics,
1666 base_predicates: &ty::GenericPredicates<'tcx>)
1667 -> ty::GenericPredicates<'tcx>
1669 ty_generic_predicates(ccx, FnSpace, generics, base_predicates)
1672 // Add the Sized bound, unless the type parameter is marked as `?Sized`.
1673 fn add_unsized_bound<'tcx>(astconv: &AstConv<'tcx>,
1674 bounds: &mut ty::BuiltinBounds,
1675 ast_bounds: &[hir::TyParamBound],
1678 let tcx = astconv.tcx();
1680 // Try to find an unbound in bounds.
1681 let mut unbound = None;
1682 for ab in ast_bounds {
1683 if let &hir::TraitTyParamBound(ref ptr, hir::TraitBoundModifier::Maybe) = ab {
1684 if unbound.is_none() {
1685 assert!(ptr.bound_lifetimes.is_empty());
1686 unbound = Some(ptr.trait_ref.clone());
1688 span_err!(tcx.sess, span, E0203,
1689 "type parameter has more than one relaxed default \
1690 bound, only one is supported");
1695 let kind_id = tcx.lang_items.require(SizedTraitLangItem);
1698 // FIXME(#8559) currently requires the unbound to be built-in.
1699 let trait_def_id = tcx.trait_ref_to_def_id(tpb);
1701 Ok(kind_id) if trait_def_id != kind_id => {
1702 tcx.sess.span_warn(span,
1703 "default bound relaxed for a type parameter, but \
1704 this does nothing because the given bound is not \
1705 a default. Only `?Sized` is supported");
1706 tcx.try_add_builtin_trait(kind_id, bounds);
1711 _ if kind_id.is_ok() => {
1712 tcx.try_add_builtin_trait(kind_id.unwrap(), bounds);
1714 // No lang item for Sized, so we can't add it as a bound.
1719 /// Returns the early-bound lifetimes declared in this generics
1720 /// listing. For anything other than fns/methods, this is just all
1721 /// the lifetimes that are declared. For fns or methods, we have to
1722 /// screen out those that do not appear in any where-clauses etc using
1723 /// `resolve_lifetime::early_bound_lifetimes`.
1724 fn early_bound_lifetimes_from_generics(space: ParamSpace,
1725 ast_generics: &hir::Generics)
1726 -> Vec<hir::LifetimeDef>
1729 SelfSpace | TypeSpace => ast_generics.lifetimes.to_vec(),
1730 FnSpace => resolve_lifetime::early_bound_lifetimes(ast_generics),
1734 fn ty_generic_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1736 ast_generics: &hir::Generics,
1737 base_predicates: &ty::GenericPredicates<'tcx>)
1738 -> ty::GenericPredicates<'tcx>
1741 let mut result = base_predicates.clone();
1743 // Collect the predicates that were written inline by the user on each
1744 // type parameter (e.g., `<T:Foo>`).
1745 for (index, param) in ast_generics.ty_params.iter().enumerate() {
1746 let index = index as u32;
1747 let param_ty = ty::ParamTy::new(space, index, param.name).to_ty(ccx.tcx);
1748 let bounds = compute_bounds(&ccx.icx(&(base_predicates, ast_generics)),
1751 SizedByDefault::Yes,
1753 let predicates = bounds.predicates(ccx.tcx, param_ty);
1754 result.predicates.extend(space, predicates.into_iter());
1757 // Collect the region predicates that were declared inline as
1758 // well. In the case of parameters declared on a fn or method, we
1759 // have to be careful to only iterate over early-bound regions.
1760 let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1761 for (index, param) in early_lifetimes.iter().enumerate() {
1762 let index = index as u32;
1764 ty::ReEarlyBound(ty::EarlyBoundRegion {
1767 name: param.lifetime.name
1769 for bound in ¶m.bounds {
1770 let bound_region = ast_region_to_region(ccx.tcx, bound);
1771 let outlives = ty::Binder(ty::OutlivesPredicate(region, bound_region));
1772 result.predicates.push(space, outlives.to_predicate());
1776 // Add in the bounds that appear in the where-clause
1777 let where_clause = &ast_generics.where_clause;
1778 for predicate in &where_clause.predicates {
1780 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
1781 let ty = ast_ty_to_ty(&ccx.icx(&(base_predicates, ast_generics)),
1783 &*bound_pred.bounded_ty);
1785 for bound in bound_pred.bounds.iter() {
1787 &hir::TyParamBound::TraitTyParamBound(ref poly_trait_ref, _) => {
1788 let mut projections = Vec::new();
1791 conv_poly_trait_ref(&ccx.icx(&(base_predicates, ast_generics)),
1796 result.predicates.push(space, trait_ref.to_predicate());
1798 for projection in &projections {
1799 result.predicates.push(space, projection.to_predicate());
1803 &hir::TyParamBound::RegionTyParamBound(ref lifetime) => {
1804 let region = ast_region_to_region(tcx, lifetime);
1805 let pred = ty::Binder(ty::OutlivesPredicate(ty, region));
1806 result.predicates.push(space, ty::Predicate::TypeOutlives(pred))
1812 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
1813 let r1 = ast_region_to_region(tcx, ®ion_pred.lifetime);
1814 for bound in ®ion_pred.bounds {
1815 let r2 = ast_region_to_region(tcx, bound);
1816 let pred = ty::Binder(ty::OutlivesPredicate(r1, r2));
1817 result.predicates.push(space, ty::Predicate::RegionOutlives(pred))
1821 &hir::WherePredicate::EqPredicate(ref eq_pred) => {
1823 tcx.sess.span_bug(eq_pred.span,
1824 "Equality constraints are not yet \
1825 implemented (#20041)")
1833 fn ty_generics<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1835 ast_generics: &hir::Generics,
1836 base_generics: &ty::Generics<'tcx>)
1837 -> ty::Generics<'tcx>
1840 let mut result = base_generics.clone();
1842 let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1843 for (i, l) in early_lifetimes.iter().enumerate() {
1844 let bounds = l.bounds.iter()
1845 .map(|l| ast_region_to_region(tcx, l))
1847 let def = ty::RegionParameterDef { name: l.lifetime.name,
1850 def_id: ccx.tcx.map.local_def_id(l.lifetime.id),
1852 result.regions.push(space, def);
1855 assert!(result.types.is_empty_in(space));
1857 // Now create the real type parameters.
1858 for i in 0..ast_generics.ty_params.len() {
1859 let def = get_or_create_type_parameter_def(ccx, ast_generics, space, i as u32);
1860 debug!("ty_generics: def for type param: {:?}, {:?}", def, space);
1861 result.types.push(space, def);
1867 fn convert_default_type_parameter<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1873 let ty = ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, &path);
1875 for leaf_ty in ty.walk() {
1876 if let ty::TyParam(p) = leaf_ty.sty {
1877 if p.space == space && p.idx >= index {
1878 span_err!(ccx.tcx.sess, path.span, E0128,
1879 "type parameters with a default cannot use \
1880 forward declared identifiers");
1882 return ccx.tcx.types.err
1890 fn get_or_create_type_parameter_def<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1891 ast_generics: &hir::Generics,
1894 -> ty::TypeParameterDef<'tcx>
1896 let param = &ast_generics.ty_params[index as usize];
1899 match tcx.ty_param_defs.borrow().get(¶m.id) {
1900 Some(d) => { return d.clone(); }
1904 let default = param.default.as_ref().map(
1905 |def| convert_default_type_parameter(ccx, def, space, index)
1908 let object_lifetime_default =
1909 compute_object_lifetime_default(ccx, param.id,
1910 ¶m.bounds, &ast_generics.where_clause);
1912 let parent = tcx.map.get_parent(param.id);
1914 if space != TypeSpace && default.is_some() {
1915 if !tcx.sess.features.borrow().default_type_parameter_fallback {
1917 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1920 format!("defaults for type parameters are only allowed on type definitions, \
1921 like `struct` or `enum`"));
1925 let def = ty::TypeParameterDef {
1929 def_id: ccx.tcx.map.local_def_id(param.id),
1930 default_def_id: ccx.tcx.map.local_def_id(parent),
1932 object_lifetime_default: object_lifetime_default,
1935 tcx.ty_param_defs.borrow_mut().insert(param.id, def.clone());
1940 /// Scan the bounds and where-clauses on a parameter to extract bounds
1941 /// of the form `T:'a` so as to determine the `ObjectLifetimeDefault`.
1942 /// This runs as part of computing the minimal type scheme, so we
1943 /// intentionally avoid just asking astconv to convert all the where
1944 /// clauses into a `ty::Predicate`. This is because that could induce
1945 /// artificial cycles.
1946 fn compute_object_lifetime_default<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1947 param_id: ast::NodeId,
1948 param_bounds: &[hir::TyParamBound],
1949 where_clause: &hir::WhereClause)
1950 -> ty::ObjectLifetimeDefault
1952 let inline_bounds = from_bounds(ccx, param_bounds);
1953 let where_bounds = from_predicates(ccx, param_id, &where_clause.predicates);
1954 let all_bounds: HashSet<_> = inline_bounds.into_iter()
1955 .chain(where_bounds)
1957 return if all_bounds.len() > 1 {
1958 ty::ObjectLifetimeDefault::Ambiguous
1959 } else if all_bounds.len() == 0 {
1960 ty::ObjectLifetimeDefault::BaseDefault
1962 ty::ObjectLifetimeDefault::Specific(
1963 all_bounds.into_iter().next().unwrap())
1966 fn from_bounds<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1967 bounds: &[hir::TyParamBound])
1971 .filter_map(|bound| {
1973 hir::TraitTyParamBound(..) =>
1975 hir::RegionTyParamBound(ref lifetime) =>
1976 Some(astconv::ast_region_to_region(ccx.tcx, lifetime)),
1982 fn from_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1983 param_id: ast::NodeId,
1984 predicates: &[hir::WherePredicate])
1988 .flat_map(|predicate| {
1990 hir::WherePredicate::BoundPredicate(ref data) => {
1991 if data.bound_lifetimes.is_empty() &&
1992 is_param(ccx.tcx, &data.bounded_ty, param_id)
1994 from_bounds(ccx, &data.bounds).into_iter()
1996 Vec::new().into_iter()
1999 hir::WherePredicate::RegionPredicate(..) |
2000 hir::WherePredicate::EqPredicate(..) => {
2001 Vec::new().into_iter()
2009 enum SizedByDefault { Yes, No, }
2011 /// Translate the AST's notion of ty param bounds (which are an enum consisting of a newtyped Ty or
2012 /// a region) to ty's notion of ty param bounds, which can either be user-defined traits, or the
2013 /// built-in trait (formerly known as kind): Send.
2014 fn compute_bounds<'tcx>(astconv: &AstConv<'tcx>,
2015 param_ty: ty::Ty<'tcx>,
2016 ast_bounds: &[hir::TyParamBound],
2017 sized_by_default: SizedByDefault,
2019 -> astconv::Bounds<'tcx>
2022 conv_param_bounds(astconv,
2027 if let SizedByDefault::Yes = sized_by_default {
2028 add_unsized_bound(astconv,
2029 &mut bounds.builtin_bounds,
2034 bounds.trait_bounds.sort_by(|a,b| a.def_id().cmp(&b.def_id()));
2039 /// Converts a specific TyParamBound from the AST into a set of
2040 /// predicates that apply to the self-type. A vector is returned
2041 /// because this can be anywhere from 0 predicates (`T:?Sized` adds no
2042 /// predicates) to 1 (`T:Foo`) to many (`T:Bar<X=i32>` adds `T:Bar`
2043 /// and `<T as Bar>::X == i32`).
2044 fn predicates_from_bound<'tcx>(astconv: &AstConv<'tcx>,
2046 bound: &hir::TyParamBound)
2047 -> Vec<ty::Predicate<'tcx>>
2050 hir::TraitTyParamBound(ref tr, hir::TraitBoundModifier::None) => {
2051 let mut projections = Vec::new();
2052 let pred = conv_poly_trait_ref(astconv, param_ty, tr, &mut projections);
2053 projections.into_iter()
2054 .map(|p| p.to_predicate())
2055 .chain(Some(pred.to_predicate()))
2058 hir::RegionTyParamBound(ref lifetime) => {
2059 let region = ast_region_to_region(astconv.tcx(), lifetime);
2060 let pred = ty::Binder(ty::OutlivesPredicate(param_ty, region));
2061 vec![ty::Predicate::TypeOutlives(pred)]
2063 hir::TraitTyParamBound(_, hir::TraitBoundModifier::Maybe) => {
2069 fn conv_poly_trait_ref<'tcx>(astconv: &AstConv<'tcx>,
2071 trait_ref: &hir::PolyTraitRef,
2072 projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
2073 -> ty::PolyTraitRef<'tcx>
2075 astconv::instantiate_poly_trait_ref(astconv,
2082 fn conv_param_bounds<'a,'tcx>(astconv: &AstConv<'tcx>,
2084 param_ty: ty::Ty<'tcx>,
2085 ast_bounds: &[hir::TyParamBound])
2086 -> astconv::Bounds<'tcx>
2088 let tcx = astconv.tcx();
2089 let astconv::PartitionedBounds {
2093 } = astconv::partition_bounds(tcx, span, &ast_bounds);
2095 let mut projection_bounds = Vec::new();
2097 let trait_bounds: Vec<ty::PolyTraitRef> =
2099 .map(|bound| conv_poly_trait_ref(astconv,
2102 &mut projection_bounds))
2105 let region_bounds: Vec<ty::Region> =
2106 region_bounds.into_iter()
2107 .map(|r| ast_region_to_region(tcx, r))
2111 region_bounds: region_bounds,
2112 builtin_bounds: builtin_bounds,
2113 trait_bounds: trait_bounds,
2114 projection_bounds: projection_bounds,
2118 fn compute_type_scheme_of_foreign_fn_decl<'a, 'tcx>(
2119 ccx: &CrateCtxt<'a, 'tcx>,
2121 ast_generics: &hir::Generics,
2123 -> ty::TypeScheme<'tcx>
2125 for i in &decl.inputs {
2126 match (*i).pat.node {
2127 hir::PatIdent(_, _, _) => (),
2130 span_err!(ccx.tcx.sess, (*i).pat.span, E0130,
2131 "patterns aren't allowed in foreign function declarations");
2136 let ty_generics = ty_generics_for_fn(ccx, ast_generics, &ty::Generics::empty());
2138 let rb = BindingRscope::new();
2139 let input_tys = decl.inputs
2141 .map(|a| ty_of_arg(&ccx.icx(ast_generics), &rb, a, None))
2144 let output = match decl.output {
2145 hir::Return(ref ty) =>
2146 ty::FnConverging(ast_ty_to_ty(&ccx.icx(ast_generics), &rb, &**ty)),
2147 hir::DefaultReturn(..) =>
2148 ty::FnConverging(ccx.tcx.mk_nil()),
2149 hir::NoReturn(..) =>
2153 let t_fn = ccx.tcx.mk_fn(None,
2154 ccx.tcx.mk_bare_fn(ty::BareFnTy {
2156 unsafety: hir::Unsafety::Unsafe,
2157 sig: ty::Binder(ty::FnSig {inputs: input_tys,
2159 variadic: decl.variadic}),
2163 generics: ty_generics,
2168 fn mk_item_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
2169 ty_generics: &ty::Generics<'tcx>)
2173 ty_generics.types.map(
2174 |def| ccx.tcx.mk_param_from_def(def));
2177 ty_generics.regions.map(
2178 |def| def.to_early_bound_region());
2180 Substs::new(types, regions)
2183 /// Checks that all the type parameters on an impl
2184 fn enforce_impl_params_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,
2185 ast_generics: &hir::Generics,
2186 impl_predicates: &mut ty::GenericPredicates<'tcx>,
2189 let impl_scheme = tcx.lookup_item_type(impl_def_id);
2190 let impl_trait_ref = tcx.impl_trait_ref(impl_def_id);
2192 assert!(impl_predicates.predicates.is_empty_in(FnSpace));
2193 assert!(impl_predicates.predicates.is_empty_in(SelfSpace));
2195 // The trait reference is an input, so find all type parameters
2196 // reachable from there, to start (if this is an inherent impl,
2197 // then just examine the self type).
2198 let mut input_parameters: HashSet<_> =
2199 ctp::parameters_for_type(impl_scheme.ty, false).into_iter().collect();
2200 if let Some(ref trait_ref) = impl_trait_ref {
2201 input_parameters.extend(ctp::parameters_for_trait_ref(trait_ref, false));
2204 ctp::setup_constraining_predicates(tcx,
2205 impl_predicates.predicates.get_mut_slice(TypeSpace),
2207 &mut input_parameters);
2209 for (index, ty_param) in ast_generics.ty_params.iter().enumerate() {
2210 let param_ty = ty::ParamTy { space: TypeSpace,
2212 name: ty_param.name };
2213 if !input_parameters.contains(&ctp::Parameter::Type(param_ty)) {
2214 report_unused_parameter(tcx, ty_param.span, "type", ¶m_ty.to_string());
2219 fn enforce_impl_lifetimes_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,
2220 ast_generics: &hir::Generics,
2222 impl_items: &[hir::ImplItem])
2224 // Every lifetime used in an associated type must be constrained.
2225 let impl_scheme = tcx.lookup_item_type(impl_def_id);
2226 let impl_predicates = tcx.lookup_predicates(impl_def_id);
2227 let impl_trait_ref = tcx.impl_trait_ref(impl_def_id);
2229 let mut input_parameters: HashSet<_> =
2230 ctp::parameters_for_type(impl_scheme.ty, false).into_iter().collect();
2231 if let Some(ref trait_ref) = impl_trait_ref {
2232 input_parameters.extend(ctp::parameters_for_trait_ref(trait_ref, false));
2234 ctp::identify_constrained_type_params(tcx,
2235 &impl_predicates.predicates.as_slice(), impl_trait_ref, &mut input_parameters);
2237 let lifetimes_in_associated_types: HashSet<_> =
2239 .map(|item| tcx.impl_or_trait_item(tcx.map.local_def_id(item.id)))
2240 .filter_map(|item| match item {
2241 ty::TypeTraitItem(ref assoc_ty) => assoc_ty.ty,
2242 ty::ConstTraitItem(..) | ty::MethodTraitItem(..) => None
2244 .flat_map(|ty| ctp::parameters_for_type(ty, true))
2245 .filter_map(|p| match p {
2246 ctp::Parameter::Type(_) => None,
2247 ctp::Parameter::Region(r) => Some(r),
2251 for (index, lifetime_def) in ast_generics.lifetimes.iter().enumerate() {
2252 let region = ty::EarlyBoundRegion { space: TypeSpace,
2253 index: index as u32,
2254 name: lifetime_def.lifetime.name };
2256 lifetimes_in_associated_types.contains(®ion) && // (*)
2257 !input_parameters.contains(&ctp::Parameter::Region(region))
2259 report_unused_parameter(tcx, lifetime_def.lifetime.span,
2260 "lifetime", ®ion.name.to_string());
2264 // (*) This is a horrible concession to reality. I think it'd be
2265 // better to just ban unconstrianed lifetimes outright, but in
2266 // practice people do non-hygenic macros like:
2269 // macro_rules! __impl_slice_eq1 {
2270 // ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
2271 // impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> {
2278 // In a concession to backwards compatbility, we continue to
2279 // permit those, so long as the lifetimes aren't used in
2280 // associated types. I believe this is sound, because lifetimes
2281 // used elsewhere are not projected back out.
2284 fn report_unused_parameter(tcx: &ty::ctxt,
2289 span_err!(tcx.sess, span, E0207,
2290 "the {} parameter `{}` is not constrained by the \
2291 impl trait, self type, or predicates",