1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::{AstConv, Bounds, SizedByDefault};
18 use crate::check::intrinsic::intrinsic_operation_unsafety;
19 use crate::constrained_generic_params as cgp;
21 use crate::middle::resolve_lifetime as rl;
22 use crate::middle::weak_lang_items;
23 use rustc::mir::mono::Linkage;
24 use rustc::ty::query::Providers;
25 use rustc::ty::subst::GenericArgKind;
26 use rustc::ty::subst::{InternalSubsts, Subst};
27 use rustc::ty::util::Discr;
28 use rustc::ty::util::IntTypeExt;
29 use rustc::ty::{self, AdtKind, Const, DefIdTree, ToPolyTraitRef, Ty, TyCtxt};
30 use rustc::ty::{ReprOptions, ToPredicate};
31 use rustc::util::captures::Captures;
32 use rustc::util::nodemap::FxHashMap;
33 use rustc_target::spec::abi;
35 use rustc_span::{Span, DUMMY_SP};
37 use syntax::ast::{Ident, MetaItemKind};
38 use syntax::attr::{list_contains_name, mark_used, InlineAttr, OptimizeAttr};
39 use syntax::feature_gate;
40 use syntax::symbol::{kw, sym, Symbol};
42 use rustc::hir::def::{CtorKind, DefKind, Res};
43 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
44 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
45 use rustc::hir::GenericParamKind;
47 use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
49 use errors::{Applicability, StashKey};
51 use rustc_error_codes::*;
53 struct OnlySelfBounds(bool);
55 ///////////////////////////////////////////////////////////////////////////
58 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: DefId) {
59 tcx.hir().visit_item_likes_in_module(
61 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
65 pub fn provide(providers: &mut Providers<'_>) {
66 *providers = Providers {
70 predicates_defined_on,
71 explicit_predicates_of,
73 type_param_predicates,
82 collect_mod_item_types,
87 ///////////////////////////////////////////////////////////////////////////
89 /// Context specific to some particular item. This is what implements
90 /// `AstConv`. It has information about the predicates that are defined
91 /// on the trait. Unfortunately, this predicate information is
92 /// available in various different forms at various points in the
93 /// process. So we can't just store a pointer to e.g., the AST or the
94 /// parsed ty form, we have to be more flexible. To this end, the
95 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
96 /// `get_type_parameter_bounds` requests, drawing the information from
97 /// the AST (`hir::Generics`), recursively.
98 pub struct ItemCtxt<'tcx> {
103 ///////////////////////////////////////////////////////////////////////////
106 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
108 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
109 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'v> {
110 NestedVisitorMap::None
112 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
113 if let hir::TyKind::Infer = t.kind {
116 hir::intravisit::walk_ty(self, t)
120 struct CollectItemTypesVisitor<'tcx> {
124 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
125 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
126 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
127 crate fn placeholder_type_error(
130 generics: &[hir::GenericParam<'_>],
131 placeholder_types: Vec<Span>,
134 if placeholder_types.is_empty() {
137 // This is the whitelist of possible parameter names that we might suggest.
138 let possible_names = ["T", "K", "L", "A", "B", "C"];
139 let used_names = generics
141 .filter_map(|p| match p.name {
142 hir::ParamName::Plain(ident) => Some(ident.name),
145 .collect::<Vec<_>>();
147 let type_name = possible_names
149 .find(|n| !used_names.contains(&Symbol::intern(n)))
150 .unwrap_or(&"ParamName");
152 let mut sugg: Vec<_> =
153 placeholder_types.iter().map(|sp| (*sp, type_name.to_string())).collect();
154 if generics.is_empty() {
155 sugg.push((ident_span.shrink_to_hi(), format!("<{}>", type_name)));
158 generics.iter().last().unwrap().span.shrink_to_hi(),
159 format!(", {}", type_name),
162 let mut err = bad_placeholder_type(tcx, placeholder_types);
164 err.multipart_suggestion(
165 "use type parameters instead",
167 Applicability::HasPlaceholders,
173 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
174 let (generics, suggest) = match &item.kind {
175 hir::ItemKind::Union(_, generics)
176 | hir::ItemKind::Enum(_, generics)
177 | hir::ItemKind::Struct(_, generics) => (&generics.params[..], true),
178 hir::ItemKind::TyAlias(_, generics) => (&generics.params[..], false),
179 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
183 let mut visitor = PlaceholderHirTyCollector::default();
184 visitor.visit_item(item);
186 placeholder_type_error(tcx, item.ident.span, generics, visitor.0, suggest);
189 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
190 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
191 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
194 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
195 convert_item(self.tcx, item.hir_id);
196 reject_placeholder_type_signatures_in_item(self.tcx, item);
197 intravisit::walk_item(self, item);
200 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
201 for param in generics.params {
203 hir::GenericParamKind::Lifetime { .. } => {}
204 hir::GenericParamKind::Type { default: Some(_), .. } => {
205 let def_id = self.tcx.hir().local_def_id(param.hir_id);
206 self.tcx.type_of(def_id);
208 hir::GenericParamKind::Type { .. } => {}
209 hir::GenericParamKind::Const { .. } => {
210 let def_id = self.tcx.hir().local_def_id(param.hir_id);
211 self.tcx.type_of(def_id);
215 intravisit::walk_generics(self, generics);
218 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
219 if let hir::ExprKind::Closure(..) = expr.kind {
220 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
221 self.tcx.generics_of(def_id);
222 self.tcx.type_of(def_id);
224 intravisit::walk_expr(self, expr);
227 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
228 convert_trait_item(self.tcx, trait_item.hir_id);
229 intravisit::walk_trait_item(self, trait_item);
232 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
233 convert_impl_item(self.tcx, impl_item.hir_id);
234 intravisit::walk_impl_item(self, impl_item);
238 ///////////////////////////////////////////////////////////////////////////
239 // Utility types and common code for the above passes.
241 fn bad_placeholder_type(
243 mut spans: Vec<Span>,
244 ) -> errors::DiagnosticBuilder<'tcx> {
246 let mut err = struct_span_err!(
250 "the type placeholder `_` is not allowed within types on item signatures",
253 err.span_label(span, "not allowed in type signatures");
258 impl ItemCtxt<'tcx> {
259 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
260 ItemCtxt { tcx, item_def_id }
263 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
264 AstConv::ast_ty_to_ty(self, ast_ty)
268 impl AstConv<'tcx> for ItemCtxt<'tcx> {
269 fn tcx(&self) -> TyCtxt<'tcx> {
273 fn item_def_id(&self) -> Option<DefId> {
274 Some(self.item_def_id)
277 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
278 self.tcx.at(span).type_param_predicates((self.item_def_id, def_id))
281 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
285 fn allow_ty_infer(&self) -> bool {
289 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
290 self.tcx().sess.delay_span_bug(span, "bad placeholder type");
297 _: Option<&ty::GenericParamDef>,
299 ) -> &'tcx Const<'tcx> {
300 bad_placeholder_type(self.tcx(), vec![span]).emit();
302 self.tcx().consts.err
305 fn projected_ty_from_poly_trait_ref(
309 item_segment: &hir::PathSegment<'_>,
310 poly_trait_ref: ty::PolyTraitRef<'tcx>,
312 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
313 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
321 self.tcx().mk_projection(item_def_id, item_substs)
323 // There are no late-bound regions; we can just ignore the binder.
328 "cannot extract an associated type from a higher-ranked trait bound \
335 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
336 // Types in item signatures are not normalized to avoid undue dependencies.
340 fn set_tainted_by_errors(&self) {
341 // There's no obvious place to track this, so just let it go.
344 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
345 // There's no place to record types from signatures?
349 /// Returns the predicates defined on `item_def_id` of the form
350 /// `X: Foo` where `X` is the type parameter `def_id`.
351 fn type_param_predicates(
353 (item_def_id, def_id): (DefId, DefId),
354 ) -> ty::GenericPredicates<'_> {
357 // In the AST, bounds can derive from two places. Either
358 // written inline like `<T: Foo>` or in a where-clause like
361 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
362 let param_owner = tcx.hir().ty_param_owner(param_id);
363 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
364 let generics = tcx.generics_of(param_owner_def_id);
365 let index = generics.param_def_id_to_index[&def_id];
366 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
368 // Don't look for bounds where the type parameter isn't in scope.
370 if item_def_id == param_owner_def_id { None } else { tcx.generics_of(item_def_id).parent };
372 let mut result = parent
374 let icx = ItemCtxt::new(tcx, parent);
375 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
377 .unwrap_or_default();
378 let mut extend = None;
380 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
381 let ast_generics = match tcx.hir().get(item_hir_id) {
382 Node::TraitItem(item) => &item.generics,
384 Node::ImplItem(item) => &item.generics,
386 Node::Item(item) => {
388 ItemKind::Fn(.., ref generics, _)
389 | ItemKind::Impl(_, _, _, ref generics, ..)
390 | ItemKind::TyAlias(_, ref generics)
391 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
392 | ItemKind::Enum(_, ref generics)
393 | ItemKind::Struct(_, ref generics)
394 | ItemKind::Union(_, ref generics) => generics,
395 ItemKind::Trait(_, _, ref generics, ..) => {
396 // Implied `Self: Trait` and supertrait bounds.
397 if param_id == item_hir_id {
398 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
399 extend = Some((identity_trait_ref.to_predicate(), item.span));
407 Node::ForeignItem(item) => match item.kind {
408 ForeignItemKind::Fn(_, _, ref generics) => generics,
415 let icx = ItemCtxt::new(tcx, item_def_id);
416 let extra_predicates = extend.into_iter().chain(
417 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
419 .filter(|(predicate, _)| match predicate {
420 ty::Predicate::Trait(ref data) => data.skip_binder().self_ty().is_param(index),
425 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
429 impl ItemCtxt<'tcx> {
430 /// Finds bounds from `hir::Generics`. This requires scanning through the
431 /// AST. We do this to avoid having to convert *all* the bounds, which
432 /// would create artificial cycles. Instead, we can only convert the
433 /// bounds for a type parameter `X` if `X::Foo` is used.
434 fn type_parameter_bounds_in_generics(
436 ast_generics: &'tcx hir::Generics<'tcx>,
437 param_id: hir::HirId,
439 only_self_bounds: OnlySelfBounds,
440 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
441 let from_ty_params = ast_generics
444 .filter_map(|param| match param.kind {
445 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
448 .flat_map(|bounds| bounds.iter())
449 .flat_map(|b| predicates_from_bound(self, ty, b));
451 let from_where_clauses = ast_generics
455 .filter_map(|wp| match *wp {
456 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
460 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
462 } else if !only_self_bounds.0 {
463 Some(self.to_ty(&bp.bounded_ty))
467 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
469 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
471 from_ty_params.chain(from_where_clauses).collect()
475 /// Tests whether this is the AST for a reference to the type
476 /// parameter with ID `param_id`. We use this so as to avoid running
477 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
478 /// conversion of the type to avoid inducing unnecessary cycles.
479 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
480 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
482 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
483 def_id == tcx.hir().local_def_id(param_id)
492 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::HirId) {
493 let it = tcx.hir().expect_item(item_id);
494 debug!("convert: item {} with id {}", it.ident, it.hir_id);
495 let def_id = tcx.hir().local_def_id(item_id);
497 // These don't define types.
498 hir::ItemKind::ExternCrate(_)
499 | hir::ItemKind::Use(..)
500 | hir::ItemKind::Mod(_)
501 | hir::ItemKind::GlobalAsm(_) => {}
502 hir::ItemKind::ForeignMod(ref foreign_mod) => {
503 for item in foreign_mod.items {
504 let def_id = tcx.hir().local_def_id(item.hir_id);
505 tcx.generics_of(def_id);
507 tcx.predicates_of(def_id);
508 if let hir::ForeignItemKind::Fn(..) = item.kind {
513 hir::ItemKind::Enum(ref enum_definition, _) => {
514 tcx.generics_of(def_id);
516 tcx.predicates_of(def_id);
517 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
519 hir::ItemKind::Impl(..) => {
520 tcx.generics_of(def_id);
522 tcx.impl_trait_ref(def_id);
523 tcx.predicates_of(def_id);
525 hir::ItemKind::Trait(..) => {
526 tcx.generics_of(def_id);
527 tcx.trait_def(def_id);
528 tcx.at(it.span).super_predicates_of(def_id);
529 tcx.predicates_of(def_id);
531 hir::ItemKind::TraitAlias(..) => {
532 tcx.generics_of(def_id);
533 tcx.at(it.span).super_predicates_of(def_id);
534 tcx.predicates_of(def_id);
536 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
537 tcx.generics_of(def_id);
539 tcx.predicates_of(def_id);
541 for f in struct_def.fields() {
542 let def_id = tcx.hir().local_def_id(f.hir_id);
543 tcx.generics_of(def_id);
545 tcx.predicates_of(def_id);
548 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
549 convert_variant_ctor(tcx, ctor_hir_id);
553 // Desugared from `impl Trait`, so visited by the function's return type.
554 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
556 hir::ItemKind::OpaqueTy(..)
557 | hir::ItemKind::TyAlias(..)
558 | hir::ItemKind::Static(..)
559 | hir::ItemKind::Const(..)
560 | hir::ItemKind::Fn(..) => {
561 tcx.generics_of(def_id);
563 tcx.predicates_of(def_id);
564 if let hir::ItemKind::Fn(..) = it.kind {
571 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
572 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
573 let def_id = tcx.hir().local_def_id(trait_item.hir_id);
574 tcx.generics_of(def_id);
576 match trait_item.kind {
577 hir::TraitItemKind::Const(..)
578 | hir::TraitItemKind::Type(_, Some(_))
579 | hir::TraitItemKind::Method(..) => {
581 if let hir::TraitItemKind::Method(..) = trait_item.kind {
586 hir::TraitItemKind::Type(_, None) => {}
589 tcx.predicates_of(def_id);
592 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
593 let def_id = tcx.hir().local_def_id(impl_item_id);
594 tcx.generics_of(def_id);
596 tcx.predicates_of(def_id);
597 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).kind {
602 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
603 let def_id = tcx.hir().local_def_id(ctor_id);
604 tcx.generics_of(def_id);
606 tcx.predicates_of(def_id);
609 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
610 let def = tcx.adt_def(def_id);
611 let repr_type = def.repr.discr_type();
612 let initial = repr_type.initial_discriminant(tcx);
613 let mut prev_discr = None::<Discr<'_>>;
615 // fill the discriminant values and field types
616 for variant in variants {
617 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
619 if let Some(ref e) = variant.disr_expr {
620 let expr_did = tcx.hir().local_def_id(e.hir_id);
621 def.eval_explicit_discr(tcx, expr_did)
622 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
625 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
628 format!("overflowed on value after {}", prev_discr.unwrap()),
631 "explicitly set `{} = {}` if that is desired outcome",
632 variant.ident, wrapped_discr
637 .unwrap_or(wrapped_discr),
640 for f in variant.data.fields() {
641 let def_id = tcx.hir().local_def_id(f.hir_id);
642 tcx.generics_of(def_id);
644 tcx.predicates_of(def_id);
647 // Convert the ctor, if any. This also registers the variant as
649 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
650 convert_variant_ctor(tcx, ctor_hir_id);
657 variant_did: Option<DefId>,
658 ctor_did: Option<DefId>,
660 discr: ty::VariantDiscr,
661 def: &hir::VariantData<'_>,
662 adt_kind: ty::AdtKind,
664 ) -> ty::VariantDef {
665 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
666 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
671 let fid = tcx.hir().local_def_id(f.hir_id);
672 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
673 if let Some(prev_span) = dup_span {
678 "field `{}` is already declared",
681 .span_label(f.span, "field already declared")
682 .span_label(prev_span, format!("`{}` first declared here", f.ident))
685 seen_fields.insert(f.ident.modern(), f.span);
691 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
695 let recovered = match def {
696 hir::VariantData::Struct(_, r) => *r,
706 CtorKind::from_hir(def),
713 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
716 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
717 let item = match tcx.hir().get(hir_id) {
718 Node::Item(item) => item,
722 let repr = ReprOptions::new(tcx, def_id);
723 let (kind, variants) = match item.kind {
724 ItemKind::Enum(ref def, _) => {
725 let mut distance_from_explicit = 0;
730 let variant_did = Some(tcx.hir().local_def_id(v.id));
732 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
734 let discr = if let Some(ref e) = v.disr_expr {
735 distance_from_explicit = 0;
736 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id))
738 ty::VariantDiscr::Relative(distance_from_explicit)
740 distance_from_explicit += 1;
755 (AdtKind::Enum, variants)
757 ItemKind::Struct(ref def, _) => {
758 let variant_did = None;
759 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
761 let variants = std::iter::once(convert_variant(
766 ty::VariantDiscr::Relative(0),
773 (AdtKind::Struct, variants)
775 ItemKind::Union(ref def, _) => {
776 let variant_did = None;
777 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
779 let variants = std::iter::once(convert_variant(
784 ty::VariantDiscr::Relative(0),
791 (AdtKind::Union, variants)
795 tcx.alloc_adt_def(def_id, kind, variants, repr)
798 /// Ensures that the super-predicates of the trait with a `DefId`
799 /// of `trait_def_id` are converted and stored. This also ensures that
800 /// the transitive super-predicates are converted.
801 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
802 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
803 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
805 let item = match tcx.hir().get(trait_hir_id) {
806 Node::Item(item) => item,
807 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
810 let (generics, bounds) = match item.kind {
811 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
812 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
813 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
816 let icx = ItemCtxt::new(tcx, trait_def_id);
818 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
819 let self_param_ty = tcx.types.self_param;
821 AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
823 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
825 // Convert any explicit superbounds in the where-clause,
826 // e.g., `trait Foo where Self: Bar`.
827 // In the case of trait aliases, however, we include all bounds in the where-clause,
828 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
829 // as one of its "superpredicates".
830 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
831 let superbounds2 = icx.type_parameter_bounds_in_generics(
835 OnlySelfBounds(!is_trait_alias),
838 // Combine the two lists to form the complete set of superbounds:
839 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
841 // Now require that immediate supertraits are converted,
842 // which will, in turn, reach indirect supertraits.
843 for &(pred, span) in superbounds {
844 debug!("superbound: {:?}", pred);
845 if let ty::Predicate::Trait(bound) = pred {
846 tcx.at(span).super_predicates_of(bound.def_id());
850 ty::GenericPredicates { parent: None, predicates: superbounds }
853 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
854 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
855 let item = tcx.hir().expect_item(hir_id);
857 let (is_auto, unsafety) = match item.kind {
858 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
859 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
860 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
863 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
864 if paren_sugar && !tcx.features().unboxed_closures {
865 let mut err = tcx.sess.struct_span_err(
867 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
868 which traits can use parenthetical notation",
872 "add `#![feature(unboxed_closures)]` to \
873 the crate attributes to use it"
878 let is_marker = tcx.has_attr(def_id, sym::marker);
879 let def_path_hash = tcx.def_path_hash(def_id);
880 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
884 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
885 struct LateBoundRegionsDetector<'tcx> {
887 outer_index: ty::DebruijnIndex,
888 has_late_bound_regions: Option<Span>,
891 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
892 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
893 NestedVisitorMap::None
896 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
897 if self.has_late_bound_regions.is_some() {
901 hir::TyKind::BareFn(..) => {
902 self.outer_index.shift_in(1);
903 intravisit::walk_ty(self, ty);
904 self.outer_index.shift_out(1);
906 _ => intravisit::walk_ty(self, ty),
910 fn visit_poly_trait_ref(
912 tr: &'tcx hir::PolyTraitRef<'tcx>,
913 m: hir::TraitBoundModifier,
915 if self.has_late_bound_regions.is_some() {
918 self.outer_index.shift_in(1);
919 intravisit::walk_poly_trait_ref(self, tr, m);
920 self.outer_index.shift_out(1);
923 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
924 if self.has_late_bound_regions.is_some() {
928 match self.tcx.named_region(lt.hir_id) {
929 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
930 Some(rl::Region::LateBound(debruijn, _, _))
931 | Some(rl::Region::LateBoundAnon(debruijn, _))
932 if debruijn < self.outer_index => {}
933 Some(rl::Region::LateBound(..))
934 | Some(rl::Region::LateBoundAnon(..))
935 | Some(rl::Region::Free(..))
937 self.has_late_bound_regions = Some(lt.span);
943 fn has_late_bound_regions<'tcx>(
945 generics: &'tcx hir::Generics<'tcx>,
946 decl: &'tcx hir::FnDecl<'tcx>,
948 let mut visitor = LateBoundRegionsDetector {
950 outer_index: ty::INNERMOST,
951 has_late_bound_regions: None,
953 for param in generics.params {
954 if let GenericParamKind::Lifetime { .. } = param.kind {
955 if tcx.is_late_bound(param.hir_id) {
956 return Some(param.span);
960 visitor.visit_fn_decl(decl);
961 visitor.has_late_bound_regions
965 Node::TraitItem(item) => match item.kind {
966 hir::TraitItemKind::Method(ref sig, _) => {
967 has_late_bound_regions(tcx, &item.generics, &sig.decl)
971 Node::ImplItem(item) => match item.kind {
972 hir::ImplItemKind::Method(ref sig, _) => {
973 has_late_bound_regions(tcx, &item.generics, &sig.decl)
977 Node::ForeignItem(item) => match item.kind {
978 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
979 has_late_bound_regions(tcx, generics, fn_decl)
983 Node::Item(item) => match item.kind {
984 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
985 has_late_bound_regions(tcx, generics, &sig.decl)
993 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
996 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
998 let node = tcx.hir().get(hir_id);
999 let parent_def_id = match node {
1001 | Node::TraitItem(_)
1004 | Node::Field(_) => {
1005 let parent_id = tcx.hir().get_parent_item(hir_id);
1006 Some(tcx.hir().local_def_id(parent_id))
1008 // FIXME(#43408) enable this always when we get lazy normalization.
1009 Node::AnonConst(_) => {
1010 // HACK(eddyb) this provides the correct generics when
1011 // `feature(const_generics)` is enabled, so that const expressions
1012 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1013 if tcx.features().const_generics {
1014 let parent_id = tcx.hir().get_parent_item(hir_id);
1015 Some(tcx.hir().local_def_id(parent_id))
1020 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1021 Some(tcx.closure_base_def_id(def_id))
1023 Node::Item(item) => match item.kind {
1024 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => impl_trait_fn,
1030 let mut opt_self = None;
1031 let mut allow_defaults = false;
1033 let no_generics = hir::Generics::empty();
1034 let ast_generics = match node {
1035 Node::TraitItem(item) => &item.generics,
1037 Node::ImplItem(item) => &item.generics,
1039 Node::Item(item) => {
1041 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
1045 ItemKind::TyAlias(_, ref generics)
1046 | ItemKind::Enum(_, ref generics)
1047 | ItemKind::Struct(_, ref generics)
1048 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1049 | ItemKind::Union(_, ref generics) => {
1050 allow_defaults = true;
1054 ItemKind::Trait(_, _, ref generics, ..)
1055 | ItemKind::TraitAlias(ref generics, ..) => {
1056 // Add in the self type parameter.
1058 // Something of a hack: use the node id for the trait, also as
1059 // the node id for the Self type parameter.
1060 let param_id = item.hir_id;
1062 opt_self = Some(ty::GenericParamDef {
1064 name: kw::SelfUpper,
1065 def_id: tcx.hir().local_def_id(param_id),
1066 pure_wrt_drop: false,
1067 kind: ty::GenericParamDefKind::Type {
1069 object_lifetime_default: rl::Set1::Empty,
1074 allow_defaults = true;
1082 Node::ForeignItem(item) => match item.kind {
1083 ForeignItemKind::Static(..) => &no_generics,
1084 ForeignItemKind::Fn(_, _, ref generics) => generics,
1085 ForeignItemKind::Type => &no_generics,
1091 let has_self = opt_self.is_some();
1092 let mut parent_has_self = false;
1093 let mut own_start = has_self as u32;
1094 let parent_count = parent_def_id.map_or(0, |def_id| {
1095 let generics = tcx.generics_of(def_id);
1096 assert_eq!(has_self, false);
1097 parent_has_self = generics.has_self;
1098 own_start = generics.count() as u32;
1099 generics.parent_count + generics.params.len()
1102 let mut params: Vec<_> = opt_self.into_iter().collect();
1104 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1105 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1106 name: param.name.ident().name,
1107 index: own_start + i as u32,
1108 def_id: tcx.hir().local_def_id(param.hir_id),
1109 pure_wrt_drop: param.pure_wrt_drop,
1110 kind: ty::GenericParamDefKind::Lifetime,
1113 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1115 // Now create the real type parameters.
1116 let type_start = own_start - has_self as u32 + params.len() as u32;
1118 params.extend(ast_generics.params.iter().filter_map(|param| {
1119 let kind = match param.kind {
1120 GenericParamKind::Type { ref default, synthetic, .. } => {
1121 if !allow_defaults && default.is_some() {
1122 if !tcx.features().default_type_parameter_fallback {
1124 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1128 "defaults for type parameters are only allowed in \
1129 `struct`, `enum`, `type`, or `trait` definitions."
1135 ty::GenericParamDefKind::Type {
1136 has_default: default.is_some(),
1137 object_lifetime_default: object_lifetime_defaults
1139 .map_or(rl::Set1::Empty, |o| o[i]),
1143 GenericParamKind::Const { .. } => ty::GenericParamDefKind::Const,
1147 let param_def = ty::GenericParamDef {
1148 index: type_start + i as u32,
1149 name: param.name.ident().name,
1150 def_id: tcx.hir().local_def_id(param.hir_id),
1151 pure_wrt_drop: param.pure_wrt_drop,
1158 // provide junk type parameter defs - the only place that
1159 // cares about anything but the length is instantiation,
1160 // and we don't do that for closures.
1161 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1162 let dummy_args = if gen.is_some() {
1163 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1165 &["<closure_kind>", "<closure_signature>"][..]
1168 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1169 index: type_start + i as u32,
1170 name: Symbol::intern(arg),
1172 pure_wrt_drop: false,
1173 kind: ty::GenericParamDefKind::Type {
1175 object_lifetime_default: rl::Set1::Empty,
1180 if let Some(upvars) = tcx.upvars(def_id) {
1181 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1182 ty::GenericParamDef {
1183 index: type_start + i,
1184 name: Symbol::intern("<upvar>"),
1186 pure_wrt_drop: false,
1187 kind: ty::GenericParamDefKind::Type {
1189 object_lifetime_default: rl::Set1::Empty,
1197 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1199 tcx.arena.alloc(ty::Generics {
1200 parent: parent_def_id,
1203 param_def_id_to_index,
1204 has_self: has_self || parent_has_self,
1205 has_late_bound_regions: has_late_bound_regions(tcx, node),
1209 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
1214 "associated types are not yet supported in inherent impls (see #8995)"
1218 fn infer_placeholder_type(
1221 body_id: hir::BodyId,
1225 let ty = tcx.diagnostic_only_typeck_tables_of(def_id).node_type(body_id.hir_id);
1227 // If this came from a free `const` or `static mut?` item,
1228 // then the user may have written e.g. `const A = 42;`.
1229 // In this case, the parser has stashed a diagnostic for
1230 // us to improve in typeck so we do that now.
1231 match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
1233 // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
1234 // We are typeck and have the real type, so remove that and suggest the actual type.
1235 err.suggestions.clear();
1236 err.span_suggestion(
1238 "provide a type for the item",
1239 format!("{}: {}", item_ident, ty),
1240 Applicability::MachineApplicable,
1245 let mut diag = bad_placeholder_type(tcx, vec![span]);
1246 if ty != tcx.types.err {
1247 diag.span_suggestion(
1249 "replace `_` with the correct type",
1251 Applicability::MaybeIncorrect,
1261 fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1264 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1266 let icx = ItemCtxt::new(tcx, def_id);
1268 match tcx.hir().get(hir_id) {
1269 Node::TraitItem(item) => match item.kind {
1270 TraitItemKind::Method(..) => {
1271 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1272 tcx.mk_fn_def(def_id, substs)
1274 TraitItemKind::Const(ref ty, body_id) => body_id
1275 .and_then(|body_id| {
1276 if is_suggestable_infer_ty(ty) {
1277 Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
1282 .unwrap_or_else(|| icx.to_ty(ty)),
1283 TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1284 TraitItemKind::Type(_, None) => {
1285 span_bug!(item.span, "associated type missing default");
1289 Node::ImplItem(item) => match item.kind {
1290 ImplItemKind::Method(..) => {
1291 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1292 tcx.mk_fn_def(def_id, substs)
1294 ImplItemKind::Const(ref ty, body_id) => {
1295 if is_suggestable_infer_ty(ty) {
1296 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1301 ImplItemKind::OpaqueTy(_) => {
1302 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1303 report_assoc_ty_on_inherent_impl(tcx, item.span);
1306 find_opaque_ty_constraints(tcx, def_id)
1308 ImplItemKind::TyAlias(ref ty) => {
1309 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1310 report_assoc_ty_on_inherent_impl(tcx, item.span);
1317 Node::Item(item) => {
1319 ItemKind::Static(ref ty, .., body_id) | ItemKind::Const(ref ty, body_id) => {
1320 if is_suggestable_infer_ty(ty) {
1321 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1326 ItemKind::TyAlias(ref ty, _) | ItemKind::Impl(.., ref ty, _) => icx.to_ty(ty),
1327 ItemKind::Fn(..) => {
1328 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1329 tcx.mk_fn_def(def_id, substs)
1331 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1332 let def = tcx.adt_def(def_id);
1333 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1334 tcx.mk_adt(def, substs)
1336 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: None, .. }) => {
1337 find_opaque_ty_constraints(tcx, def_id)
1339 // Opaque types desugared from `impl Trait`.
1340 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(owner), .. }) => {
1341 tcx.typeck_tables_of(owner)
1342 .concrete_opaque_types
1344 .map(|opaque| opaque.concrete_type)
1345 .unwrap_or_else(|| {
1346 // This can occur if some error in the
1347 // owner fn prevented us from populating
1348 // the `concrete_opaque_types` table.
1349 tcx.sess.delay_span_bug(
1352 "owner {:?} has no opaque type for {:?} in its tables",
1360 | ItemKind::TraitAlias(..)
1362 | ItemKind::ForeignMod(..)
1363 | ItemKind::GlobalAsm(..)
1364 | ItemKind::ExternCrate(..)
1365 | ItemKind::Use(..) => {
1368 "compute_type_of_item: unexpected item type: {:?}",
1375 Node::ForeignItem(foreign_item) => match foreign_item.kind {
1376 ForeignItemKind::Fn(..) => {
1377 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1378 tcx.mk_fn_def(def_id, substs)
1380 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1381 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1384 Node::Ctor(&ref def) | Node::Variant(hir::Variant { data: ref def, .. }) => match *def {
1385 VariantData::Unit(..) | VariantData::Struct(..) => {
1386 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1388 VariantData::Tuple(..) => {
1389 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1390 tcx.mk_fn_def(def_id, substs)
1394 Node::Field(field) => icx.to_ty(&field.ty),
1396 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) => {
1398 return tcx.typeck_tables_of(def_id).node_type(hir_id);
1401 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1402 tcx.mk_closure(def_id, substs)
1405 Node::AnonConst(_) => {
1406 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1408 Node::Ty(&hir::Ty { kind: hir::TyKind::Array(_, ref constant), .. })
1409 | Node::Ty(&hir::Ty { kind: hir::TyKind::Typeof(ref constant), .. })
1410 | Node::Expr(&hir::Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1411 if constant.hir_id == hir_id =>
1416 Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => {
1417 tcx.adt_def(tcx.hir().get_parent_did(hir_id)).repr.discr_type().to_ty(tcx)
1420 Node::Ty(&hir::Ty { kind: hir::TyKind::Path(_), .. })
1421 | Node::Expr(&hir::Expr { kind: ExprKind::Struct(..), .. })
1422 | Node::Expr(&hir::Expr { kind: ExprKind::Path(_), .. })
1423 | Node::TraitRef(..) => {
1424 let path = match parent_node {
1426 kind: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1429 | Node::Expr(&hir::Expr {
1430 kind: ExprKind::Path(QPath::Resolved(_, ref path)),
1432 }) => Some(&**path),
1433 Node::Expr(&hir::Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
1434 if let QPath::Resolved(_, ref path) = **path {
1440 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
1444 if let Some(path) = path {
1445 let arg_index = path
1448 .filter_map(|seg| seg.args.as_ref())
1449 .map(|generic_args| generic_args.args.as_ref())
1452 .filter(|arg| arg.is_const())
1454 .filter(|(_, arg)| arg.id() == hir_id)
1455 .map(|(index, _)| index)
1458 .unwrap_or_else(|| {
1459 bug!("no arg matching AnonConst in path");
1462 // We've encountered an `AnonConst` in some path, so we need to
1463 // figure out which generic parameter it corresponds to and return
1464 // the relevant type.
1465 let generics = match path.res {
1466 Res::Def(DefKind::Ctor(..), def_id) => {
1467 tcx.generics_of(tcx.parent(def_id).unwrap())
1469 Res::Def(_, def_id) => tcx.generics_of(def_id),
1470 Res::Err => return tcx.types.err,
1472 tcx.sess.delay_span_bug(
1474 &format!("unexpected const parent path def {:?}", res,),
1476 return tcx.types.err;
1484 if let ty::GenericParamDefKind::Const = param.kind {
1491 .map(|param| tcx.type_of(param.def_id))
1492 // This is no generic parameter associated with the arg. This is
1493 // probably from an extra arg where one is not needed.
1494 .unwrap_or(tcx.types.err)
1496 tcx.sess.delay_span_bug(
1498 &format!("unexpected const parent path {:?}", parent_node,),
1500 return tcx.types.err;
1505 tcx.sess.delay_span_bug(
1507 &format!("unexpected const parent in type_of_def_id(): {:?}", x),
1514 Node::GenericParam(param) => {
1516 hir::GenericParamKind::Type { default: Some(ref ty), .. } => icx.to_ty(ty),
1517 hir::GenericParamKind::Const { ty: ref hir_ty, .. } => {
1518 let ty = icx.to_ty(hir_ty);
1519 if !tcx.features().const_compare_raw_pointers {
1520 let err = match ty.peel_refs().kind {
1521 ty::FnPtr(_) => Some("function pointers"),
1522 ty::RawPtr(_) => Some("raw pointers"),
1525 if let Some(unsupported_type) = err {
1526 feature_gate::feature_err(
1527 &tcx.sess.parse_sess,
1528 sym::const_compare_raw_pointers,
1531 "using {} as const generic parameters is unstable",
1538 if ty::search_for_structural_match_violation(param.hir_id, param.span, tcx, ty)
1545 "the types of const generic parameters must derive `PartialEq` and `Eq`",
1548 format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
1553 x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
1558 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1563 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1564 use rustc::hir::{ImplItem, Item, TraitItem};
1566 debug!("find_opaque_ty_constraints({:?})", def_id);
1568 struct ConstraintLocator<'tcx> {
1571 // (first found type span, actual type, mapping from the opaque type's generic
1572 // parameters to the concrete type's generic parameters)
1574 // The mapping is an index for each use site of a generic parameter in the concrete type
1576 // The indices index into the generic parameters on the opaque type.
1577 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1580 impl ConstraintLocator<'tcx> {
1581 fn check(&mut self, def_id: DefId) {
1582 // Don't try to check items that cannot possibly constrain the type.
1583 if !self.tcx.has_typeck_tables(def_id) {
1585 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1586 self.def_id, def_id,
1590 let ty = self.tcx.typeck_tables_of(def_id).concrete_opaque_types.get(&self.def_id);
1591 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1593 "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1594 self.def_id, def_id, ty,
1597 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1598 let span = self.tcx.def_span(def_id);
1599 // used to quickly look up the position of a generic parameter
1600 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1601 // Skipping binder is ok, since we only use this to find generic parameters and
1603 for (idx, subst) in substs.iter().enumerate() {
1604 if let GenericArgKind::Type(ty) = subst.unpack() {
1605 if let ty::Param(p) = ty.kind {
1606 if index_map.insert(p, idx).is_some() {
1607 // There was already an entry for `p`, meaning a generic parameter
1609 self.tcx.sess.span_err(
1612 "defining opaque type use restricts opaque \
1613 type by using the generic parameter `{}` twice",
1620 self.tcx.sess.delay_span_bug(
1623 "non-defining opaque ty use in defining scope: {:?}, {:?}",
1624 concrete_type, substs,
1630 // Compute the index within the opaque type for each generic parameter used in
1631 // the concrete type.
1632 let indices = concrete_type
1633 .subst(self.tcx, substs)
1635 .filter_map(|t| match &t.kind {
1636 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1640 let is_param = |ty: Ty<'_>| match ty.kind {
1641 ty::Param(_) => true,
1644 let bad_substs: Vec<_> =
1645 substs.types().enumerate().filter(|(_, ty)| !is_param(ty)).collect();
1646 if !bad_substs.is_empty() {
1647 let identity_substs = InternalSubsts::identity_for_item(self.tcx, self.def_id);
1648 for (i, bad_subst) in bad_substs {
1649 self.tcx.sess.span_err(
1652 "defining opaque type use does not fully define opaque type: \
1653 generic parameter `{}` is specified as concrete type `{}`",
1654 identity_substs.type_at(i),
1659 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1660 let mut ty = concrete_type.walk().fuse();
1661 let mut p_ty = prev_ty.walk().fuse();
1662 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.kind, &p.kind) {
1663 // Type parameters are equal to any other type parameter for the purpose of
1664 // concrete type equality, as it is possible to obtain the same type just
1665 // by passing matching parameters to a function.
1666 (ty::Param(_), ty::Param(_)) => true,
1669 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1670 debug!("find_opaque_ty_constraints: span={:?}", span);
1671 // Found different concrete types for the opaque type.
1672 let mut err = self.tcx.sess.struct_span_err(
1674 "concrete type differs from previous defining opaque type use",
1678 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1680 err.span_note(prev_span, "previous use here");
1682 } else if indices != *prev_indices {
1683 // Found "same" concrete types, but the generic parameter order differs.
1684 let mut err = self.tcx.sess.struct_span_err(
1686 "concrete type's generic parameters differ from previous defining use",
1688 use std::fmt::Write;
1689 let mut s = String::new();
1690 write!(s, "expected [").unwrap();
1691 let list = |s: &mut String, indices: &Vec<usize>| {
1692 let mut indices = indices.iter().cloned();
1693 if let Some(first) = indices.next() {
1694 write!(s, "`{}`", substs[first]).unwrap();
1696 write!(s, ", `{}`", substs[i]).unwrap();
1700 list(&mut s, prev_indices);
1701 write!(s, "], got [").unwrap();
1702 list(&mut s, &indices);
1703 write!(s, "]").unwrap();
1704 err.span_label(span, s);
1705 err.span_note(prev_span, "previous use here");
1709 self.found = Some((span, concrete_type, indices));
1713 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
1714 self.def_id, def_id,
1720 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1721 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1722 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1724 fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
1725 debug!("find_existential_constraints: visiting {:?}", it);
1726 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1727 // The opaque type itself or its children are not within its reveal scope.
1728 if def_id != self.def_id {
1730 intravisit::walk_item(self, it);
1733 fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
1734 debug!("find_existential_constraints: visiting {:?}", it);
1735 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1736 // The opaque type itself or its children are not within its reveal scope.
1737 if def_id != self.def_id {
1739 intravisit::walk_impl_item(self, it);
1742 fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
1743 debug!("find_existential_constraints: visiting {:?}", it);
1744 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1746 intravisit::walk_trait_item(self, it);
1750 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1751 let scope = tcx.hir().get_defining_scope(hir_id);
1752 let mut locator = ConstraintLocator { def_id, tcx, found: None };
1754 debug!("find_opaque_ty_constraints: scope={:?}", scope);
1756 if scope == hir::CRATE_HIR_ID {
1757 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1759 debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
1760 match tcx.hir().get(scope) {
1761 // We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
1762 // This allows our visitor to process the defining item itself, causing
1763 // it to pick up any 'sibling' defining uses.
1765 // For example, this code:
1768 // type Blah = impl Debug;
1769 // let my_closure = || -> Blah { true };
1773 // requires us to explicitly process `foo()` in order
1774 // to notice the defining usage of `Blah`.
1775 Node::Item(ref it) => locator.visit_item(it),
1776 Node::ImplItem(ref it) => locator.visit_impl_item(it),
1777 Node::TraitItem(ref it) => locator.visit_trait_item(it),
1778 other => bug!("{:?} is not a valid scope for an opaque type item", other),
1782 match locator.found {
1783 Some((_, ty, _)) => ty,
1785 let span = tcx.def_span(def_id);
1786 tcx.sess.span_err(span, "could not find defining uses");
1792 /// Whether `ty` is a type with `_` placeholders that can be infered. Used in diagnostics only to
1793 /// use inference to provide suggestions for the appropriate type if possible.
1794 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1796 hir::TyKind::Infer => true,
1797 hir::TyKind::Slice(ty) | hir::TyKind::Array(ty, _) => is_suggestable_infer_ty(ty),
1798 hir::TyKind::Tup(tys) => tys.iter().any(|ty| is_suggestable_infer_ty(ty)),
1803 pub fn get_infer_ret_ty(output: &'hir hir::FunctionRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1804 if let hir::FunctionRetTy::Return(ref ty) = output {
1805 if is_suggestable_infer_ty(ty) {
1812 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1813 use rustc::hir::Node::*;
1816 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1818 let icx = ItemCtxt::new(tcx, def_id);
1820 match tcx.hir().get(hir_id) {
1821 TraitItem(hir::TraitItem {
1822 kind: TraitItemKind::Method(sig, TraitMethod::Provided(_)),
1827 | ImplItem(hir::ImplItem { kind: ImplItemKind::Method(sig, _), ident, generics, .. })
1828 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1829 match get_infer_ret_ty(&sig.decl.output) {
1831 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1832 let mut visitor = PlaceholderHirTyCollector::default();
1833 visitor.visit_ty(ty);
1834 let mut diag = bad_placeholder_type(tcx, visitor.0);
1835 let ret_ty = fn_sig.output();
1836 if ret_ty != tcx.types.err {
1837 diag.span_suggestion(
1839 "replace with the correct return type",
1841 Applicability::MaybeIncorrect,
1845 ty::Binder::bind(fn_sig)
1847 None => AstConv::ty_of_fn(
1849 sig.header.unsafety,
1852 &generics.params[..],
1858 TraitItem(hir::TraitItem {
1859 kind: TraitItemKind::Method(FnSig { header, decl }, _),
1863 }) => AstConv::ty_of_fn(
1868 &generics.params[..],
1872 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(ref fn_decl, _, _), .. }) => {
1873 let abi = tcx.hir().get_foreign_abi(hir_id);
1874 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1877 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1878 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1880 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1881 ty::Binder::bind(tcx.mk_fn_sig(
1885 hir::Unsafety::Normal,
1890 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1891 // Closure signatures are not like other function
1892 // signatures and cannot be accessed through `fn_sig`. For
1893 // example, a closure signature excludes the `self`
1894 // argument. In any case they are embedded within the
1895 // closure type as part of the `ClosureSubsts`.
1898 // the signature of a closure, you should use the
1899 // `closure_sig` method on the `ClosureSubsts`:
1901 // closure_substs.sig(def_id, tcx)
1903 // or, inside of an inference context, you can use
1905 // infcx.closure_sig(def_id, closure_substs)
1906 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1910 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1915 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1916 let icx = ItemCtxt::new(tcx, def_id);
1918 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1919 match tcx.hir().expect_item(hir_id).kind {
1920 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1921 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1922 let selfty = tcx.type_of(def_id);
1923 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1930 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1931 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1932 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1933 let item = tcx.hir().expect_item(hir_id);
1935 hir::ItemKind::Impl(_, hir::ImplPolarity::Negative, ..) => {
1936 if is_rustc_reservation {
1937 tcx.sess.span_err(item.span, "reservation impls can't be negative");
1939 ty::ImplPolarity::Negative
1941 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, None, _, _) => {
1942 if is_rustc_reservation {
1943 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1945 ty::ImplPolarity::Positive
1947 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, Some(_tr), _, _) => {
1948 if is_rustc_reservation {
1949 ty::ImplPolarity::Reservation
1951 ty::ImplPolarity::Positive
1954 ref item => bug!("impl_polarity: {:?} not an impl", item),
1958 /// Returns the early-bound lifetimes declared in this generics
1959 /// listing. For anything other than fns/methods, this is just all
1960 /// the lifetimes that are declared. For fns or methods, we have to
1961 /// screen out those that do not appear in any where-clauses etc using
1962 /// `resolve_lifetime::early_bound_lifetimes`.
1963 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1965 generics: &'a hir::Generics<'a>,
1966 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1967 generics.params.iter().filter(move |param| match param.kind {
1968 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1973 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1974 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1975 /// inferred constraints concerning which regions outlive other regions.
1976 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1977 debug!("predicates_defined_on({:?})", def_id);
1978 let mut result = tcx.explicit_predicates_of(def_id);
1979 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1980 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1981 if !inferred_outlives.is_empty() {
1983 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1984 def_id, inferred_outlives,
1986 if result.predicates.is_empty() {
1987 result.predicates = inferred_outlives;
1989 result.predicates = tcx
1991 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1994 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1998 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1999 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2000 /// `Self: Trait` predicates for traits.
2001 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2002 let mut result = tcx.predicates_defined_on(def_id);
2004 if tcx.is_trait(def_id) {
2005 // For traits, add `Self: Trait` predicate. This is
2006 // not part of the predicates that a user writes, but it
2007 // is something that one must prove in order to invoke a
2008 // method or project an associated type.
2010 // In the chalk setup, this predicate is not part of the
2011 // "predicates" for a trait item. But it is useful in
2012 // rustc because if you directly (e.g.) invoke a trait
2013 // method like `Trait::method(...)`, you must naturally
2014 // prove that the trait applies to the types that were
2015 // used, and adding the predicate into this list ensures
2016 // that this is done.
2017 let span = tcx.def_span(def_id);
2019 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2020 ty::TraitRef::identity(tcx, def_id).to_predicate(),
2024 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2028 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2029 /// N.B., this does not include any implied/inferred constraints.
2030 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2032 use rustc_data_structures::fx::FxHashSet;
2034 debug!("explicit_predicates_of(def_id={:?})", def_id);
2036 /// A data structure with unique elements, which preserves order of insertion.
2037 /// Preserving the order of insertion is important here so as not to break
2038 /// compile-fail UI tests.
2039 // FIXME(eddyb) just use `IndexSet` from `indexmap`.
2040 struct UniquePredicates<'tcx> {
2041 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
2042 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
2045 impl<'tcx> UniquePredicates<'tcx> {
2047 UniquePredicates { predicates: vec![], uniques: FxHashSet::default() }
2050 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
2051 if self.uniques.insert(value) {
2052 self.predicates.push(value);
2056 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
2063 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
2064 let node = tcx.hir().get(hir_id);
2066 let mut is_trait = None;
2067 let mut is_default_impl_trait = None;
2069 let icx = ItemCtxt::new(tcx, def_id);
2071 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2073 let mut predicates = UniquePredicates::new();
2075 let ast_generics = match node {
2076 Node::TraitItem(item) => &item.generics,
2078 Node::ImplItem(item) => match item.kind {
2079 ImplItemKind::OpaqueTy(ref bounds) => {
2080 ty::print::with_no_queries(|| {
2081 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2082 let opaque_ty = tcx.mk_opaque(def_id, substs);
2084 "explicit_predicates_of({:?}): created opaque type {:?}",
2088 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2089 let bounds = AstConv::compute_bounds(
2093 SizedByDefault::Yes,
2094 tcx.def_span(def_id),
2097 predicates.extend(bounds.predicates(tcx, opaque_ty));
2101 _ => &item.generics,
2104 Node::Item(item) => {
2106 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
2107 if defaultness.is_default() {
2108 is_default_impl_trait = tcx.impl_trait_ref(def_id);
2112 ItemKind::Fn(.., ref generics, _)
2113 | ItemKind::TyAlias(_, ref generics)
2114 | ItemKind::Enum(_, ref generics)
2115 | ItemKind::Struct(_, ref generics)
2116 | ItemKind::Union(_, ref generics) => generics,
2118 ItemKind::Trait(_, _, ref generics, .., items) => {
2119 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
2122 ItemKind::TraitAlias(ref generics, _) => {
2123 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &[]));
2126 ItemKind::OpaqueTy(OpaqueTy {
2132 let bounds_predicates = ty::print::with_no_queries(|| {
2133 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2134 let opaque_ty = tcx.mk_opaque(def_id, substs);
2136 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2137 let bounds = AstConv::compute_bounds(
2141 SizedByDefault::Yes,
2142 tcx.def_span(def_id),
2145 bounds.predicates(tcx, opaque_ty)
2147 if impl_trait_fn.is_some() {
2149 return ty::GenericPredicates {
2151 predicates: tcx.arena.alloc_from_iter(bounds_predicates),
2154 // named opaque types
2155 predicates.extend(bounds_predicates);
2164 Node::ForeignItem(item) => match item.kind {
2165 ForeignItemKind::Static(..) => NO_GENERICS,
2166 ForeignItemKind::Fn(_, _, ref generics) => generics,
2167 ForeignItemKind::Type => NO_GENERICS,
2173 let generics = tcx.generics_of(def_id);
2174 let parent_count = generics.parent_count as u32;
2175 let has_own_self = generics.has_self && parent_count == 0;
2177 // Below we'll consider the bounds on the type parameters (including `Self`)
2178 // and the explicit where-clauses, but to get the full set of predicates
2179 // on a trait we need to add in the supertrait bounds and bounds found on
2180 // associated types.
2181 if let Some((_trait_ref, _)) = is_trait {
2182 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2185 // In default impls, we can assume that the self type implements
2186 // the trait. So in:
2188 // default impl Foo for Bar { .. }
2190 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2191 // (see below). Recall that a default impl is not itself an impl, but rather a
2192 // set of defaults that can be incorporated into another impl.
2193 if let Some(trait_ref) = is_default_impl_trait {
2194 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2197 // Collect the region predicates that were declared inline as
2198 // well. In the case of parameters declared on a fn or method, we
2199 // have to be careful to only iterate over early-bound regions.
2200 let mut index = parent_count + has_own_self as u32;
2201 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2202 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2203 def_id: tcx.hir().local_def_id(param.hir_id),
2205 name: param.name.ident().name,
2210 GenericParamKind::Lifetime { .. } => {
2211 param.bounds.iter().for_each(|bound| match bound {
2212 hir::GenericBound::Outlives(lt) => {
2213 let bound = AstConv::ast_region_to_region(&icx, <, None);
2214 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2215 predicates.push((outlives.to_predicate(), lt.span));
2224 // Collect the predicates that were written inline by the user on each
2225 // type parameter (e.g., `<T: Foo>`).
2226 for param in ast_generics.params {
2227 if let GenericParamKind::Type { .. } = param.kind {
2228 let name = param.name.ident().name;
2229 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2232 let sized = SizedByDefault::Yes;
2233 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2234 predicates.extend(bounds.predicates(tcx, param_ty));
2238 // Add in the bounds that appear in the where-clause.
2239 let where_clause = &ast_generics.where_clause;
2240 for predicate in where_clause.predicates {
2242 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2243 let ty = icx.to_ty(&bound_pred.bounded_ty);
2245 // Keep the type around in a dummy predicate, in case of no bounds.
2246 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2247 // is still checked for WF.
2248 if bound_pred.bounds.is_empty() {
2249 if let ty::Param(_) = ty.kind {
2250 // This is a `where T:`, which can be in the HIR from the
2251 // transformation that moves `?Sized` to `T`'s declaration.
2252 // We can skip the predicate because type parameters are
2253 // trivially WF, but also we *should*, to avoid exposing
2254 // users who never wrote `where Type:,` themselves, to
2255 // compiler/tooling bugs from not handling WF predicates.
2257 let span = bound_pred.bounded_ty.span;
2258 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2260 ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)),
2266 for bound in bound_pred.bounds.iter() {
2268 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2269 let mut bounds = Bounds::default();
2270 let _ = AstConv::instantiate_poly_trait_ref(
2276 predicates.extend(bounds.predicates(tcx, ty));
2279 &hir::GenericBound::Outlives(ref lifetime) => {
2280 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2281 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2282 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2288 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2289 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2290 predicates.extend(region_pred.bounds.iter().map(|bound| {
2291 let (r2, span) = match bound {
2292 hir::GenericBound::Outlives(lt) => {
2293 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2297 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2299 (ty::Predicate::RegionOutlives(pred), span)
2303 &hir::WherePredicate::EqPredicate(..) => {
2309 // Add predicates from associated type bounds.
2310 if let Some((self_trait_ref, trait_items)) = is_trait {
2311 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2312 associated_item_predicates(tcx, def_id, self_trait_ref, trait_item_ref)
2316 let mut predicates = predicates.predicates;
2318 // Subtle: before we store the predicates into the tcx, we
2319 // sort them so that predicates like `T: Foo<Item=U>` come
2320 // before uses of `U`. This avoids false ambiguity errors
2321 // in trait checking. See `setup_constraining_predicates`
2323 if let Node::Item(&Item { kind: ItemKind::Impl(..), .. }) = node {
2324 let self_ty = tcx.type_of(def_id);
2325 let trait_ref = tcx.impl_trait_ref(def_id);
2326 cgp::setup_constraining_predicates(
2330 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2334 let result = ty::GenericPredicates {
2335 parent: generics.parent,
2336 predicates: tcx.arena.alloc_from_iter(predicates),
2338 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2342 fn associated_item_predicates(
2345 self_trait_ref: ty::TraitRef<'tcx>,
2346 trait_item_ref: &hir::TraitItemRef,
2347 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2348 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2349 let item_def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
2350 let bounds = match trait_item.kind {
2351 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2352 _ => return Vec::new(),
2355 let is_gat = !tcx.generics_of(item_def_id).params.is_empty();
2357 let mut had_error = false;
2359 let mut unimplemented_error = |arg_kind: &str| {
2364 &format!("{}-generic associated types are not yet implemented", arg_kind),
2366 .note("for more information, see https://github.com/rust-lang/rust/issues/44265")
2372 let mk_bound_param = |param: &ty::GenericParamDef, _: &_| {
2374 ty::GenericParamDefKind::Lifetime => tcx
2375 .mk_region(ty::RegionKind::ReLateBound(
2377 ty::BoundRegion::BrNamed(param.def_id, param.name),
2380 // FIXME(generic_associated_types): Use bound types and constants
2381 // once they are handled by the trait system.
2382 ty::GenericParamDefKind::Type { .. } => {
2383 unimplemented_error("type");
2384 tcx.types.err.into()
2386 ty::GenericParamDefKind::Const => {
2387 unimplemented_error("const");
2388 tcx.consts.err.into()
2393 let bound_substs = if is_gat {
2396 // trait X<'a, B, const C: usize> {
2397 // type T<'d, E, const F: usize>: Default;
2400 // We need to create predicates on the trait:
2402 // for<'d, E, const F: usize>
2403 // <Self as X<'a, B, const C: usize>>::T<'d, E, const F: usize>: Sized + Default
2405 // We substitute escaping bound parameters for the generic
2406 // arguments to the associated type which are then bound by
2407 // the `Binder` around the the predicate.
2409 // FIXME(generic_associated_types): Currently only lifetimes are handled.
2410 self_trait_ref.substs.extend_to(tcx, item_def_id, mk_bound_param)
2412 self_trait_ref.substs
2415 let assoc_ty = tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id), bound_substs);
2417 let bounds = AstConv::compute_bounds(
2418 &ItemCtxt::new(tcx, def_id),
2421 SizedByDefault::Yes,
2425 let predicates = bounds.predicates(tcx, assoc_ty);
2428 // We use shifts to get the regions that we're substituting to
2429 // be bound by the binders in the `Predicate`s rather that
2431 let shifted_in = ty::fold::shift_vars(tcx, &predicates, 1);
2432 let substituted = shifted_in.subst(tcx, bound_substs);
2433 ty::fold::shift_out_vars(tcx, &substituted, 1)
2439 /// Converts a specific `GenericBound` from the AST into a set of
2440 /// predicates that apply to the self type. A vector is returned
2441 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2442 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2443 /// and `<T as Bar>::X == i32`).
2444 fn predicates_from_bound<'tcx>(
2445 astconv: &dyn AstConv<'tcx>,
2447 bound: &'tcx hir::GenericBound<'tcx>,
2448 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2450 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2451 let mut bounds = Bounds::default();
2452 let _ = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut bounds);
2453 bounds.predicates(astconv.tcx(), param_ty)
2455 hir::GenericBound::Outlives(ref lifetime) => {
2456 let region = astconv.ast_region_to_region(lifetime, None);
2457 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2458 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2460 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2464 fn compute_sig_of_foreign_fn_decl<'tcx>(
2467 decl: &'tcx hir::FnDecl<'tcx>,
2469 ) -> ty::PolyFnSig<'tcx> {
2470 let unsafety = if abi == abi::Abi::RustIntrinsic {
2471 intrinsic_operation_unsafety(&tcx.item_name(def_id).as_str())
2473 hir::Unsafety::Unsafe
2475 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl, &[], None);
2477 // Feature gate SIMD types in FFI, since I am not sure that the
2478 // ABIs are handled at all correctly. -huonw
2479 if abi != abi::Abi::RustIntrinsic
2480 && abi != abi::Abi::PlatformIntrinsic
2481 && !tcx.features().simd_ffi
2483 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2489 "use of SIMD type `{}` in FFI is highly experimental and \
2490 may result in invalid code",
2491 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2494 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2498 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2501 if let hir::Return(ref ty) = decl.output {
2502 check(&ty, *fty.output().skip_binder())
2509 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2510 match tcx.hir().get_if_local(def_id) {
2511 Some(Node::ForeignItem(..)) => true,
2513 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2517 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2518 match tcx.hir().get_if_local(def_id) {
2519 Some(Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. }))
2520 | Some(Node::ForeignItem(&hir::ForeignItem {
2521 kind: hir::ForeignItemKind::Static(_, mutbl),
2525 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2529 fn from_target_feature(
2532 attr: &ast::Attribute,
2533 whitelist: &FxHashMap<String, Option<Symbol>>,
2534 target_features: &mut Vec<Symbol>,
2536 let list = match attr.meta_item_list() {
2540 let bad_item = |span| {
2541 let msg = "malformed `target_feature` attribute input";
2542 let code = "enable = \"..\"".to_owned();
2544 .struct_span_err(span, &msg)
2545 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2548 let rust_features = tcx.features();
2550 // Only `enable = ...` is accepted in the meta-item list.
2551 if !item.check_name(sym::enable) {
2552 bad_item(item.span());
2556 // Must be of the form `enable = "..."` (a string).
2557 let value = match item.value_str() {
2558 Some(value) => value,
2560 bad_item(item.span());
2565 // We allow comma separation to enable multiple features.
2566 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2567 // Only allow whitelisted features per platform.
2568 let feature_gate = match whitelist.get(feature) {
2572 format!("the feature named `{}` is not valid for this target", feature);
2573 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2576 format!("`{}` is not valid for this target", feature),
2578 if feature.starts_with("+") {
2579 let valid = whitelist.contains_key(&feature[1..]);
2581 err.help("consider removing the leading `+` in the feature name");
2589 // Only allow features whose feature gates have been enabled.
2590 let allowed = match feature_gate.as_ref().map(|s| *s) {
2591 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2592 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2593 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2594 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2595 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2596 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2597 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2598 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2599 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2600 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2601 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2602 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2603 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2604 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2605 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2606 Some(name) => bug!("unknown target feature gate {}", name),
2609 if !allowed && id.is_local() {
2610 feature_gate::feature_err(
2611 &tcx.sess.parse_sess,
2612 feature_gate.unwrap(),
2614 &format!("the target feature `{}` is currently unstable", feature),
2618 Some(Symbol::intern(feature))
2623 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2624 use rustc::mir::mono::Linkage::*;
2626 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2627 // applicable to variable declarations and may not really make sense for
2628 // Rust code in the first place but whitelist them anyway and trust that
2629 // the user knows what s/he's doing. Who knows, unanticipated use cases
2630 // may pop up in the future.
2632 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2633 // and don't have to be, LLVM treats them as no-ops.
2635 "appending" => Appending,
2636 "available_externally" => AvailableExternally,
2638 "extern_weak" => ExternalWeak,
2639 "external" => External,
2640 "internal" => Internal,
2641 "linkonce" => LinkOnceAny,
2642 "linkonce_odr" => LinkOnceODR,
2643 "private" => Private,
2645 "weak_odr" => WeakODR,
2647 let span = tcx.hir().span_if_local(def_id);
2648 if let Some(span) = span {
2649 tcx.sess.span_fatal(span, "invalid linkage specified")
2651 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2657 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2658 let attrs = tcx.get_attrs(id);
2660 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2662 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2664 let mut inline_span = None;
2665 let mut link_ordinal_span = None;
2666 for attr in attrs.iter() {
2667 if attr.check_name(sym::cold) {
2668 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2669 } else if attr.check_name(sym::rustc_allocator) {
2670 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2671 } else if attr.check_name(sym::unwind) {
2672 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2673 } else if attr.check_name(sym::ffi_returns_twice) {
2674 if tcx.is_foreign_item(id) {
2675 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2677 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2682 "`#[ffi_returns_twice]` may only be used on foreign functions"
2686 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2687 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2688 } else if attr.check_name(sym::naked) {
2689 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2690 } else if attr.check_name(sym::no_mangle) {
2691 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2692 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2693 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2694 } else if attr.check_name(sym::no_debug) {
2695 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2696 } else if attr.check_name(sym::used) {
2697 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2698 } else if attr.check_name(sym::thread_local) {
2699 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2700 } else if attr.check_name(sym::track_caller) {
2701 if tcx.fn_sig(id).abi() != abi::Abi::Rust {
2702 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2705 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2706 } else if attr.check_name(sym::export_name) {
2707 if let Some(s) = attr.value_str() {
2708 if s.as_str().contains("\0") {
2709 // `#[export_name = ...]` will be converted to a null-terminated string,
2710 // so it may not contain any null characters.
2715 "`export_name` may not contain null characters"
2719 codegen_fn_attrs.export_name = Some(s);
2721 } else if attr.check_name(sym::target_feature) {
2722 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2723 let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
2725 .struct_span_err(attr.span, msg)
2726 .span_label(attr.span, "can only be applied to `unsafe` functions")
2727 .span_label(tcx.def_span(id), "not an `unsafe` function")
2730 from_target_feature(tcx, id, attr, &whitelist, &mut codegen_fn_attrs.target_features);
2731 } else if attr.check_name(sym::linkage) {
2732 if let Some(val) = attr.value_str() {
2733 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2735 } else if attr.check_name(sym::link_section) {
2736 if let Some(val) = attr.value_str() {
2737 if val.as_str().bytes().any(|b| b == 0) {
2739 "illegal null byte in link_section \
2743 tcx.sess.span_err(attr.span, &msg);
2745 codegen_fn_attrs.link_section = Some(val);
2748 } else if attr.check_name(sym::link_name) {
2749 codegen_fn_attrs.link_name = attr.value_str();
2750 } else if attr.check_name(sym::link_ordinal) {
2751 link_ordinal_span = Some(attr.span);
2752 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2753 codegen_fn_attrs.link_ordinal = ordinal;
2758 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2759 if !attr.has_name(sym::inline) {
2762 match attr.meta().map(|i| i.kind) {
2763 Some(MetaItemKind::Word) => {
2767 Some(MetaItemKind::List(ref items)) => {
2769 inline_span = Some(attr.span);
2770 if items.len() != 1 {
2771 span_err!(tcx.sess.diagnostic(), attr.span, E0534, "expected one argument");
2773 } else if list_contains_name(&items[..], sym::always) {
2775 } else if list_contains_name(&items[..], sym::never) {
2778 span_err!(tcx.sess.diagnostic(), items[0].span(), E0535, "invalid argument");
2783 Some(MetaItemKind::NameValue(_)) => ia,
2788 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2789 if !attr.has_name(sym::optimize) {
2792 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2793 match attr.meta().map(|i| i.kind) {
2794 Some(MetaItemKind::Word) => {
2795 err(attr.span, "expected one argument");
2798 Some(MetaItemKind::List(ref items)) => {
2800 inline_span = Some(attr.span);
2801 if items.len() != 1 {
2802 err(attr.span, "expected one argument");
2804 } else if list_contains_name(&items[..], sym::size) {
2806 } else if list_contains_name(&items[..], sym::speed) {
2809 err(items[0].span(), "invalid argument");
2813 Some(MetaItemKind::NameValue(_)) => ia,
2818 // If a function uses #[target_feature] it can't be inlined into general
2819 // purpose functions as they wouldn't have the right target features
2820 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2823 if codegen_fn_attrs.target_features.len() > 0 {
2824 if codegen_fn_attrs.inline == InlineAttr::Always {
2825 if let Some(span) = inline_span {
2828 "cannot use `#[inline(always)]` with \
2829 `#[target_feature]`",
2835 // Weak lang items have the same semantics as "std internal" symbols in the
2836 // sense that they're preserved through all our LTO passes and only
2837 // strippable by the linker.
2839 // Additionally weak lang items have predetermined symbol names.
2840 if tcx.is_weak_lang_item(id) {
2841 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2843 if let Some(name) = weak_lang_items::link_name(&attrs) {
2844 codegen_fn_attrs.export_name = Some(name);
2845 codegen_fn_attrs.link_name = Some(name);
2847 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2849 // Internal symbols to the standard library all have no_mangle semantics in
2850 // that they have defined symbol names present in the function name. This
2851 // also applies to weak symbols where they all have known symbol names.
2852 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2853 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2859 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
2860 use syntax::ast::{Lit, LitIntType, LitKind};
2861 let meta_item_list = attr.meta_item_list();
2862 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
2863 let sole_meta_list = match meta_item_list {
2864 Some([item]) => item.literal(),
2867 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
2868 if *ordinal <= std::usize::MAX as u128 {
2869 Some(*ordinal as usize)
2871 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
2873 .struct_span_err(attr.span, &msg)
2874 .note("the value may not exceed `std::usize::MAX`")
2880 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
2881 .note("an unsuffixed integer value, e.g., `1`, is expected")
2887 fn check_link_name_xor_ordinal(
2889 codegen_fn_attrs: &CodegenFnAttrs,
2890 inline_span: Option<Span>,
2892 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
2895 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
2896 if let Some(span) = inline_span {
2897 tcx.sess.span_err(span, msg);