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 errors::{struct_span_err, Applicability, StashKey};
24 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
25 use rustc::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
26 use rustc::mir::mono::Linkage;
28 use rustc::ty::query::Providers;
29 use rustc::ty::subst::GenericArgKind;
30 use rustc::ty::subst::{InternalSubsts, Subst};
31 use rustc::ty::util::Discr;
32 use rustc::ty::util::IntTypeExt;
33 use rustc::ty::{self, AdtKind, Const, DefIdTree, ToPolyTraitRef, Ty, TyCtxt};
34 use rustc::ty::{ReprOptions, ToPredicate};
35 use rustc::util::captures::Captures;
36 use rustc_data_structures::fx::FxHashMap;
38 use rustc_hir::def::{CtorKind, DefKind, Res};
39 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
40 use rustc_hir::{GenericParamKind, Node, Unsafety};
41 use rustc_span::symbol::{kw, sym, Symbol};
42 use rustc_span::{Span, DUMMY_SP};
43 use rustc_target::spec::abi;
45 use syntax::ast::{Ident, MetaItemKind};
46 use syntax::attr::{list_contains_name, mark_used, InlineAttr, OptimizeAttr};
47 use syntax::feature_gate;
49 use rustc_error_codes::*;
51 struct OnlySelfBounds(bool);
53 ///////////////////////////////////////////////////////////////////////////
56 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: DefId) {
57 tcx.hir().visit_item_likes_in_module(
59 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
63 pub fn provide(providers: &mut Providers<'_>) {
64 *providers = Providers {
68 predicates_defined_on,
69 explicit_predicates_of,
71 type_param_predicates,
80 collect_mod_item_types,
85 ///////////////////////////////////////////////////////////////////////////
87 /// Context specific to some particular item. This is what implements
88 /// `AstConv`. It has information about the predicates that are defined
89 /// on the trait. Unfortunately, this predicate information is
90 /// available in various different forms at various points in the
91 /// process. So we can't just store a pointer to e.g., the AST or the
92 /// parsed ty form, we have to be more flexible. To this end, the
93 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
94 /// `get_type_parameter_bounds` requests, drawing the information from
95 /// the AST (`hir::Generics`), recursively.
96 pub struct ItemCtxt<'tcx> {
101 ///////////////////////////////////////////////////////////////////////////
104 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
106 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
107 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'v> {
108 NestedVisitorMap::None
110 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
111 if let hir::TyKind::Infer = t.kind {
114 intravisit::walk_ty(self, t)
118 struct CollectItemTypesVisitor<'tcx> {
122 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
123 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
124 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
125 crate fn placeholder_type_error(
128 generics: &[hir::GenericParam<'_>],
129 placeholder_types: Vec<Span>,
132 if placeholder_types.is_empty() {
135 // This is the whitelist of possible parameter names that we might suggest.
136 let possible_names = ["T", "K", "L", "A", "B", "C"];
137 let used_names = generics
139 .filter_map(|p| match p.name {
140 hir::ParamName::Plain(ident) => Some(ident.name),
143 .collect::<Vec<_>>();
145 let type_name = possible_names
147 .find(|n| !used_names.contains(&Symbol::intern(n)))
148 .unwrap_or(&"ParamName");
150 let mut sugg: Vec<_> =
151 placeholder_types.iter().map(|sp| (*sp, type_name.to_string())).collect();
152 if generics.is_empty() {
153 sugg.push((ident_span.shrink_to_hi(), format!("<{}>", type_name)));
156 generics.iter().last().unwrap().span.shrink_to_hi(),
157 format!(", {}", type_name),
160 let mut err = bad_placeholder_type(tcx, placeholder_types);
162 err.multipart_suggestion(
163 "use type parameters instead",
165 Applicability::HasPlaceholders,
171 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
172 let (generics, suggest) = match &item.kind {
173 hir::ItemKind::Union(_, generics)
174 | hir::ItemKind::Enum(_, generics)
175 | hir::ItemKind::Struct(_, generics) => (&generics.params[..], true),
176 hir::ItemKind::TyAlias(_, generics) => (&generics.params[..], false),
177 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
181 let mut visitor = PlaceholderHirTyCollector::default();
182 visitor.visit_item(item);
184 placeholder_type_error(tcx, item.ident.span, generics, visitor.0, suggest);
187 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
188 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
189 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
192 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
193 convert_item(self.tcx, item.hir_id);
194 reject_placeholder_type_signatures_in_item(self.tcx, item);
195 intravisit::walk_item(self, item);
198 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
199 for param in generics.params {
201 hir::GenericParamKind::Lifetime { .. } => {}
202 hir::GenericParamKind::Type { default: Some(_), .. } => {
203 let def_id = self.tcx.hir().local_def_id(param.hir_id);
204 self.tcx.type_of(def_id);
206 hir::GenericParamKind::Type { .. } => {}
207 hir::GenericParamKind::Const { .. } => {
208 let def_id = self.tcx.hir().local_def_id(param.hir_id);
209 self.tcx.type_of(def_id);
213 intravisit::walk_generics(self, generics);
216 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
217 if let hir::ExprKind::Closure(..) = expr.kind {
218 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
219 self.tcx.generics_of(def_id);
220 self.tcx.type_of(def_id);
222 intravisit::walk_expr(self, expr);
225 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
226 convert_trait_item(self.tcx, trait_item.hir_id);
227 intravisit::walk_trait_item(self, trait_item);
230 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
231 convert_impl_item(self.tcx, impl_item.hir_id);
232 intravisit::walk_impl_item(self, impl_item);
236 ///////////////////////////////////////////////////////////////////////////
237 // Utility types and common code for the above passes.
239 fn bad_placeholder_type(
241 mut spans: Vec<Span>,
242 ) -> errors::DiagnosticBuilder<'tcx> {
244 let mut err = struct_span_err!(
248 "the type placeholder `_` is not allowed within types on item signatures",
251 err.span_label(span, "not allowed in type signatures");
256 impl ItemCtxt<'tcx> {
257 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
258 ItemCtxt { tcx, item_def_id }
261 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
262 AstConv::ast_ty_to_ty(self, ast_ty)
266 impl AstConv<'tcx> for ItemCtxt<'tcx> {
267 fn tcx(&self) -> TyCtxt<'tcx> {
271 fn item_def_id(&self) -> Option<DefId> {
272 Some(self.item_def_id)
275 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
276 self.tcx.at(span).type_param_predicates((self.item_def_id, def_id))
279 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
283 fn allow_ty_infer(&self) -> bool {
287 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
288 self.tcx().sess.delay_span_bug(span, "bad placeholder type");
295 _: Option<&ty::GenericParamDef>,
297 ) -> &'tcx Const<'tcx> {
298 bad_placeholder_type(self.tcx(), vec![span]).emit();
300 self.tcx().consts.err
303 fn projected_ty_from_poly_trait_ref(
307 item_segment: &hir::PathSegment<'_>,
308 poly_trait_ref: ty::PolyTraitRef<'tcx>,
310 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
311 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
319 self.tcx().mk_projection(item_def_id, item_substs)
321 // There are no late-bound regions; we can just ignore the binder.
326 "cannot extract an associated type from a higher-ranked trait bound \
334 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
335 // Types in item signatures are not normalized to avoid undue dependencies.
339 fn set_tainted_by_errors(&self) {
340 // There's no obvious place to track this, so just let it go.
343 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
344 // There's no place to record types from signatures?
348 /// Returns the predicates defined on `item_def_id` of the form
349 /// `X: Foo` where `X` is the type parameter `def_id`.
350 fn type_param_predicates(
352 (item_def_id, def_id): (DefId, DefId),
353 ) -> ty::GenericPredicates<'_> {
356 // In the AST, bounds can derive from two places. Either
357 // written inline like `<T: Foo>` or in a where-clause like
360 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
361 let param_owner = tcx.hir().ty_param_owner(param_id);
362 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
363 let generics = tcx.generics_of(param_owner_def_id);
364 let index = generics.param_def_id_to_index[&def_id];
365 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
367 // Don't look for bounds where the type parameter isn't in scope.
369 if item_def_id == param_owner_def_id { None } else { tcx.generics_of(item_def_id).parent };
371 let mut result = parent
373 let icx = ItemCtxt::new(tcx, parent);
374 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
376 .unwrap_or_default();
377 let mut extend = None;
379 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
380 let ast_generics = match tcx.hir().get(item_hir_id) {
381 Node::TraitItem(item) => &item.generics,
383 Node::ImplItem(item) => &item.generics,
385 Node::Item(item) => {
387 ItemKind::Fn(.., ref generics, _)
388 | ItemKind::Impl(_, _, _, ref generics, ..)
389 | ItemKind::TyAlias(_, ref generics)
390 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
391 | ItemKind::Enum(_, ref generics)
392 | ItemKind::Struct(_, ref generics)
393 | ItemKind::Union(_, ref generics) => generics,
394 ItemKind::Trait(_, _, ref generics, ..) => {
395 // Implied `Self: Trait` and supertrait bounds.
396 if param_id == item_hir_id {
397 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
398 extend = Some((identity_trait_ref.to_predicate(), item.span));
406 Node::ForeignItem(item) => match item.kind {
407 ForeignItemKind::Fn(_, _, ref generics) => generics,
414 let icx = ItemCtxt::new(tcx, item_def_id);
415 let extra_predicates = extend.into_iter().chain(
416 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
418 .filter(|(predicate, _)| match predicate {
419 ty::Predicate::Trait(ref data) => data.skip_binder().self_ty().is_param(index),
424 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
428 impl ItemCtxt<'tcx> {
429 /// Finds bounds from `hir::Generics`. This requires scanning through the
430 /// AST. We do this to avoid having to convert *all* the bounds, which
431 /// would create artificial cycles. Instead, we can only convert the
432 /// bounds for a type parameter `X` if `X::Foo` is used.
433 fn type_parameter_bounds_in_generics(
435 ast_generics: &'tcx hir::Generics<'tcx>,
436 param_id: hir::HirId,
438 only_self_bounds: OnlySelfBounds,
439 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
440 let from_ty_params = ast_generics
443 .filter_map(|param| match param.kind {
444 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
447 .flat_map(|bounds| bounds.iter())
448 .flat_map(|b| predicates_from_bound(self, ty, b));
450 let from_where_clauses = ast_generics
454 .filter_map(|wp| match *wp {
455 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
459 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
461 } else if !only_self_bounds.0 {
462 Some(self.to_ty(&bp.bounded_ty))
466 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
468 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
470 from_ty_params.chain(from_where_clauses).collect()
474 /// Tests whether this is the AST for a reference to the type
475 /// parameter with ID `param_id`. We use this so as to avoid running
476 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
477 /// conversion of the type to avoid inducing unnecessary cycles.
478 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
479 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
481 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
482 def_id == tcx.hir().local_def_id(param_id)
491 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::HirId) {
492 let it = tcx.hir().expect_item(item_id);
493 debug!("convert: item {} with id {}", it.ident, it.hir_id);
494 let def_id = tcx.hir().local_def_id(item_id);
496 // These don't define types.
497 hir::ItemKind::ExternCrate(_)
498 | hir::ItemKind::Use(..)
499 | hir::ItemKind::Mod(_)
500 | hir::ItemKind::GlobalAsm(_) => {}
501 hir::ItemKind::ForeignMod(ref foreign_mod) => {
502 for item in foreign_mod.items {
503 let def_id = tcx.hir().local_def_id(item.hir_id);
504 tcx.generics_of(def_id);
506 tcx.predicates_of(def_id);
507 if let hir::ForeignItemKind::Fn(..) = item.kind {
512 hir::ItemKind::Enum(ref enum_definition, _) => {
513 tcx.generics_of(def_id);
515 tcx.predicates_of(def_id);
516 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
518 hir::ItemKind::Impl(..) => {
519 tcx.generics_of(def_id);
521 tcx.impl_trait_ref(def_id);
522 tcx.predicates_of(def_id);
524 hir::ItemKind::Trait(..) => {
525 tcx.generics_of(def_id);
526 tcx.trait_def(def_id);
527 tcx.at(it.span).super_predicates_of(def_id);
528 tcx.predicates_of(def_id);
530 hir::ItemKind::TraitAlias(..) => {
531 tcx.generics_of(def_id);
532 tcx.at(it.span).super_predicates_of(def_id);
533 tcx.predicates_of(def_id);
535 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
536 tcx.generics_of(def_id);
538 tcx.predicates_of(def_id);
540 for f in struct_def.fields() {
541 let def_id = tcx.hir().local_def_id(f.hir_id);
542 tcx.generics_of(def_id);
544 tcx.predicates_of(def_id);
547 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
548 convert_variant_ctor(tcx, ctor_hir_id);
552 // Desugared from `impl Trait`, so visited by the function's return type.
553 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
555 hir::ItemKind::OpaqueTy(..)
556 | hir::ItemKind::TyAlias(..)
557 | hir::ItemKind::Static(..)
558 | hir::ItemKind::Const(..)
559 | hir::ItemKind::Fn(..) => {
560 tcx.generics_of(def_id);
562 tcx.predicates_of(def_id);
563 if let hir::ItemKind::Fn(..) = it.kind {
570 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
571 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
572 let def_id = tcx.hir().local_def_id(trait_item.hir_id);
573 tcx.generics_of(def_id);
575 match trait_item.kind {
576 hir::TraitItemKind::Const(..)
577 | hir::TraitItemKind::Type(_, Some(_))
578 | hir::TraitItemKind::Method(..) => {
580 if let hir::TraitItemKind::Method(..) = trait_item.kind {
585 hir::TraitItemKind::Type(_, None) => {}
588 tcx.predicates_of(def_id);
591 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
592 let def_id = tcx.hir().local_def_id(impl_item_id);
593 tcx.generics_of(def_id);
595 tcx.predicates_of(def_id);
596 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).kind {
601 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
602 let def_id = tcx.hir().local_def_id(ctor_id);
603 tcx.generics_of(def_id);
605 tcx.predicates_of(def_id);
608 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
609 let def = tcx.adt_def(def_id);
610 let repr_type = def.repr.discr_type();
611 let initial = repr_type.initial_discriminant(tcx);
612 let mut prev_discr = None::<Discr<'_>>;
614 // fill the discriminant values and field types
615 for variant in variants {
616 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
618 if let Some(ref e) = variant.disr_expr {
619 let expr_did = tcx.hir().local_def_id(e.hir_id);
620 def.eval_explicit_discr(tcx, expr_did)
621 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
624 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
627 format!("overflowed on value after {}", prev_discr.unwrap()),
630 "explicitly set `{} = {}` if that is desired outcome",
631 variant.ident, wrapped_discr
636 .unwrap_or(wrapped_discr),
639 for f in variant.data.fields() {
640 let def_id = tcx.hir().local_def_id(f.hir_id);
641 tcx.generics_of(def_id);
643 tcx.predicates_of(def_id);
646 // Convert the ctor, if any. This also registers the variant as
648 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
649 convert_variant_ctor(tcx, ctor_hir_id);
656 variant_did: Option<DefId>,
657 ctor_did: Option<DefId>,
659 discr: ty::VariantDiscr,
660 def: &hir::VariantData<'_>,
661 adt_kind: ty::AdtKind,
663 ) -> ty::VariantDef {
664 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
665 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
670 let fid = tcx.hir().local_def_id(f.hir_id);
671 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
672 if let Some(prev_span) = dup_span {
677 "field `{}` is already declared",
680 .span_label(f.span, "field already declared")
681 .span_label(prev_span, format!("`{}` first declared here", f.ident))
684 seen_fields.insert(f.ident.modern(), f.span);
690 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
694 let recovered = match def {
695 hir::VariantData::Struct(_, r) => *r,
705 CtorKind::from_hir(def),
712 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
715 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
716 let item = match tcx.hir().get(hir_id) {
717 Node::Item(item) => item,
721 let repr = ReprOptions::new(tcx, def_id);
722 let (kind, variants) = match item.kind {
723 ItemKind::Enum(ref def, _) => {
724 let mut distance_from_explicit = 0;
729 let variant_did = Some(tcx.hir().local_def_id(v.id));
731 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
733 let discr = if let Some(ref e) = v.disr_expr {
734 distance_from_explicit = 0;
735 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id))
737 ty::VariantDiscr::Relative(distance_from_explicit)
739 distance_from_explicit += 1;
754 (AdtKind::Enum, variants)
756 ItemKind::Struct(ref def, _) => {
757 let variant_did = None;
758 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
760 let variants = std::iter::once(convert_variant(
765 ty::VariantDiscr::Relative(0),
772 (AdtKind::Struct, variants)
774 ItemKind::Union(ref def, _) => {
775 let variant_did = None;
776 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
778 let variants = std::iter::once(convert_variant(
783 ty::VariantDiscr::Relative(0),
790 (AdtKind::Union, variants)
794 tcx.alloc_adt_def(def_id, kind, variants, repr)
797 /// Ensures that the super-predicates of the trait with a `DefId`
798 /// of `trait_def_id` are converted and stored. This also ensures that
799 /// the transitive super-predicates are converted.
800 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
801 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
802 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
804 let item = match tcx.hir().get(trait_hir_id) {
805 Node::Item(item) => item,
806 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
809 let (generics, bounds) = match item.kind {
810 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
811 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
812 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
815 let icx = ItemCtxt::new(tcx, trait_def_id);
817 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
818 let self_param_ty = tcx.types.self_param;
820 AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
822 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
824 // Convert any explicit superbounds in the where-clause,
825 // e.g., `trait Foo where Self: Bar`.
826 // In the case of trait aliases, however, we include all bounds in the where-clause,
827 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
828 // as one of its "superpredicates".
829 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
830 let superbounds2 = icx.type_parameter_bounds_in_generics(
834 OnlySelfBounds(!is_trait_alias),
837 // Combine the two lists to form the complete set of superbounds:
838 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
840 // Now require that immediate supertraits are converted,
841 // which will, in turn, reach indirect supertraits.
842 for &(pred, span) in superbounds {
843 debug!("superbound: {:?}", pred);
844 if let ty::Predicate::Trait(bound) = pred {
845 tcx.at(span).super_predicates_of(bound.def_id());
849 ty::GenericPredicates { parent: None, predicates: superbounds }
852 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
853 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
854 let item = tcx.hir().expect_item(hir_id);
856 let (is_auto, unsafety) = match item.kind {
857 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
858 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
859 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
862 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
863 if paren_sugar && !tcx.features().unboxed_closures {
867 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
868 which traits can use parenthetical notation",
870 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
874 let is_marker = tcx.has_attr(def_id, sym::marker);
875 let def_path_hash = tcx.def_path_hash(def_id);
876 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
880 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
881 struct LateBoundRegionsDetector<'tcx> {
883 outer_index: ty::DebruijnIndex,
884 has_late_bound_regions: Option<Span>,
887 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
888 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
889 NestedVisitorMap::None
892 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
893 if self.has_late_bound_regions.is_some() {
897 hir::TyKind::BareFn(..) => {
898 self.outer_index.shift_in(1);
899 intravisit::walk_ty(self, ty);
900 self.outer_index.shift_out(1);
902 _ => intravisit::walk_ty(self, ty),
906 fn visit_poly_trait_ref(
908 tr: &'tcx hir::PolyTraitRef<'tcx>,
909 m: hir::TraitBoundModifier,
911 if self.has_late_bound_regions.is_some() {
914 self.outer_index.shift_in(1);
915 intravisit::walk_poly_trait_ref(self, tr, m);
916 self.outer_index.shift_out(1);
919 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
920 if self.has_late_bound_regions.is_some() {
924 match self.tcx.named_region(lt.hir_id) {
925 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
926 Some(rl::Region::LateBound(debruijn, _, _))
927 | Some(rl::Region::LateBoundAnon(debruijn, _))
928 if debruijn < self.outer_index => {}
929 Some(rl::Region::LateBound(..))
930 | Some(rl::Region::LateBoundAnon(..))
931 | Some(rl::Region::Free(..))
933 self.has_late_bound_regions = Some(lt.span);
939 fn has_late_bound_regions<'tcx>(
941 generics: &'tcx hir::Generics<'tcx>,
942 decl: &'tcx hir::FnDecl<'tcx>,
944 let mut visitor = LateBoundRegionsDetector {
946 outer_index: ty::INNERMOST,
947 has_late_bound_regions: None,
949 for param in generics.params {
950 if let GenericParamKind::Lifetime { .. } = param.kind {
951 if tcx.is_late_bound(param.hir_id) {
952 return Some(param.span);
956 visitor.visit_fn_decl(decl);
957 visitor.has_late_bound_regions
961 Node::TraitItem(item) => match item.kind {
962 hir::TraitItemKind::Method(ref sig, _) => {
963 has_late_bound_regions(tcx, &item.generics, &sig.decl)
967 Node::ImplItem(item) => match item.kind {
968 hir::ImplItemKind::Method(ref sig, _) => {
969 has_late_bound_regions(tcx, &item.generics, &sig.decl)
973 Node::ForeignItem(item) => match item.kind {
974 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
975 has_late_bound_regions(tcx, generics, fn_decl)
979 Node::Item(item) => match item.kind {
980 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
981 has_late_bound_regions(tcx, generics, &sig.decl)
989 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
992 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
994 let node = tcx.hir().get(hir_id);
995 let parent_def_id = match node {
1000 | Node::Field(_) => {
1001 let parent_id = tcx.hir().get_parent_item(hir_id);
1002 Some(tcx.hir().local_def_id(parent_id))
1004 // FIXME(#43408) enable this always when we get lazy normalization.
1005 Node::AnonConst(_) => {
1006 // HACK(eddyb) this provides the correct generics when
1007 // `feature(const_generics)` is enabled, so that const expressions
1008 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1009 if tcx.features().const_generics {
1010 let parent_id = tcx.hir().get_parent_item(hir_id);
1011 Some(tcx.hir().local_def_id(parent_id))
1016 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1017 Some(tcx.closure_base_def_id(def_id))
1019 Node::Item(item) => match item.kind {
1020 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => impl_trait_fn,
1026 let mut opt_self = None;
1027 let mut allow_defaults = false;
1029 let no_generics = hir::Generics::empty();
1030 let ast_generics = match node {
1031 Node::TraitItem(item) => &item.generics,
1033 Node::ImplItem(item) => &item.generics,
1035 Node::Item(item) => {
1037 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
1041 ItemKind::TyAlias(_, ref generics)
1042 | ItemKind::Enum(_, ref generics)
1043 | ItemKind::Struct(_, ref generics)
1044 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1045 | ItemKind::Union(_, ref generics) => {
1046 allow_defaults = true;
1050 ItemKind::Trait(_, _, ref generics, ..)
1051 | ItemKind::TraitAlias(ref generics, ..) => {
1052 // Add in the self type parameter.
1054 // Something of a hack: use the node id for the trait, also as
1055 // the node id for the Self type parameter.
1056 let param_id = item.hir_id;
1058 opt_self = Some(ty::GenericParamDef {
1060 name: kw::SelfUpper,
1061 def_id: tcx.hir().local_def_id(param_id),
1062 pure_wrt_drop: false,
1063 kind: ty::GenericParamDefKind::Type {
1065 object_lifetime_default: rl::Set1::Empty,
1070 allow_defaults = true;
1078 Node::ForeignItem(item) => match item.kind {
1079 ForeignItemKind::Static(..) => &no_generics,
1080 ForeignItemKind::Fn(_, _, ref generics) => generics,
1081 ForeignItemKind::Type => &no_generics,
1087 let has_self = opt_self.is_some();
1088 let mut parent_has_self = false;
1089 let mut own_start = has_self as u32;
1090 let parent_count = parent_def_id.map_or(0, |def_id| {
1091 let generics = tcx.generics_of(def_id);
1092 assert_eq!(has_self, false);
1093 parent_has_self = generics.has_self;
1094 own_start = generics.count() as u32;
1095 generics.parent_count + generics.params.len()
1098 let mut params: Vec<_> = opt_self.into_iter().collect();
1100 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1101 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1102 name: param.name.ident().name,
1103 index: own_start + i as u32,
1104 def_id: tcx.hir().local_def_id(param.hir_id),
1105 pure_wrt_drop: param.pure_wrt_drop,
1106 kind: ty::GenericParamDefKind::Lifetime,
1109 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1111 // Now create the real type parameters.
1112 let type_start = own_start - has_self as u32 + params.len() as u32;
1114 params.extend(ast_generics.params.iter().filter_map(|param| {
1115 let kind = match param.kind {
1116 GenericParamKind::Type { ref default, synthetic, .. } => {
1117 if !allow_defaults && default.is_some() {
1118 if !tcx.features().default_type_parameter_fallback {
1120 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1124 "defaults for type parameters are only allowed in \
1125 `struct`, `enum`, `type`, or `trait` definitions."
1131 ty::GenericParamDefKind::Type {
1132 has_default: default.is_some(),
1133 object_lifetime_default: object_lifetime_defaults
1135 .map_or(rl::Set1::Empty, |o| o[i]),
1139 GenericParamKind::Const { .. } => ty::GenericParamDefKind::Const,
1143 let param_def = ty::GenericParamDef {
1144 index: type_start + i as u32,
1145 name: param.name.ident().name,
1146 def_id: tcx.hir().local_def_id(param.hir_id),
1147 pure_wrt_drop: param.pure_wrt_drop,
1154 // provide junk type parameter defs - the only place that
1155 // cares about anything but the length is instantiation,
1156 // and we don't do that for closures.
1157 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1158 let dummy_args = if gen.is_some() {
1159 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1161 &["<closure_kind>", "<closure_signature>"][..]
1164 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1165 index: type_start + i as u32,
1166 name: Symbol::intern(arg),
1168 pure_wrt_drop: false,
1169 kind: ty::GenericParamDefKind::Type {
1171 object_lifetime_default: rl::Set1::Empty,
1176 if let Some(upvars) = tcx.upvars(def_id) {
1177 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1178 ty::GenericParamDef {
1179 index: type_start + i,
1180 name: Symbol::intern("<upvar>"),
1182 pure_wrt_drop: false,
1183 kind: ty::GenericParamDefKind::Type {
1185 object_lifetime_default: rl::Set1::Empty,
1193 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1195 tcx.arena.alloc(ty::Generics {
1196 parent: parent_def_id,
1199 param_def_id_to_index,
1200 has_self: has_self || parent_has_self,
1201 has_late_bound_regions: has_late_bound_regions(tcx, node),
1205 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
1210 "associated types are not yet supported in inherent impls (see #8995)"
1215 fn infer_placeholder_type(
1218 body_id: hir::BodyId,
1222 let ty = tcx.diagnostic_only_typeck_tables_of(def_id).node_type(body_id.hir_id);
1224 // If this came from a free `const` or `static mut?` item,
1225 // then the user may have written e.g. `const A = 42;`.
1226 // In this case, the parser has stashed a diagnostic for
1227 // us to improve in typeck so we do that now.
1228 match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
1230 // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
1231 // We are typeck and have the real type, so remove that and suggest the actual type.
1232 err.suggestions.clear();
1233 err.span_suggestion(
1235 "provide a type for the item",
1236 format!("{}: {}", item_ident, ty),
1237 Applicability::MachineApplicable,
1242 let mut diag = bad_placeholder_type(tcx, vec![span]);
1243 if ty != tcx.types.err {
1244 diag.span_suggestion(
1246 "replace `_` with the correct type",
1248 Applicability::MaybeIncorrect,
1258 fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1261 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1263 let icx = ItemCtxt::new(tcx, def_id);
1265 match tcx.hir().get(hir_id) {
1266 Node::TraitItem(item) => match item.kind {
1267 TraitItemKind::Method(..) => {
1268 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1269 tcx.mk_fn_def(def_id, substs)
1271 TraitItemKind::Const(ref ty, body_id) => body_id
1272 .and_then(|body_id| {
1273 if is_suggestable_infer_ty(ty) {
1274 Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
1279 .unwrap_or_else(|| icx.to_ty(ty)),
1280 TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1281 TraitItemKind::Type(_, None) => {
1282 span_bug!(item.span, "associated type missing default");
1286 Node::ImplItem(item) => match item.kind {
1287 ImplItemKind::Method(..) => {
1288 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1289 tcx.mk_fn_def(def_id, substs)
1291 ImplItemKind::Const(ref ty, body_id) => {
1292 if is_suggestable_infer_ty(ty) {
1293 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1298 ImplItemKind::OpaqueTy(_) => {
1299 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1300 report_assoc_ty_on_inherent_impl(tcx, item.span);
1303 find_opaque_ty_constraints(tcx, def_id)
1305 ImplItemKind::TyAlias(ref ty) => {
1306 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1307 report_assoc_ty_on_inherent_impl(tcx, item.span);
1314 Node::Item(item) => {
1316 ItemKind::Static(ref ty, .., body_id) | ItemKind::Const(ref ty, body_id) => {
1317 if is_suggestable_infer_ty(ty) {
1318 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1323 ItemKind::TyAlias(ref ty, _) | ItemKind::Impl(.., ref ty, _) => icx.to_ty(ty),
1324 ItemKind::Fn(..) => {
1325 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1326 tcx.mk_fn_def(def_id, substs)
1328 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1329 let def = tcx.adt_def(def_id);
1330 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1331 tcx.mk_adt(def, substs)
1333 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: None, .. }) => {
1334 find_opaque_ty_constraints(tcx, def_id)
1336 // Opaque types desugared from `impl Trait`.
1337 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(owner), .. }) => {
1338 tcx.typeck_tables_of(owner)
1339 .concrete_opaque_types
1341 .map(|opaque| opaque.concrete_type)
1342 .unwrap_or_else(|| {
1343 // This can occur if some error in the
1344 // owner fn prevented us from populating
1345 // the `concrete_opaque_types` table.
1346 tcx.sess.delay_span_bug(
1349 "owner {:?} has no opaque type for {:?} in its tables",
1357 | ItemKind::TraitAlias(..)
1359 | ItemKind::ForeignMod(..)
1360 | ItemKind::GlobalAsm(..)
1361 | ItemKind::ExternCrate(..)
1362 | ItemKind::Use(..) => {
1365 "compute_type_of_item: unexpected item type: {:?}",
1372 Node::ForeignItem(foreign_item) => match foreign_item.kind {
1373 ForeignItemKind::Fn(..) => {
1374 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1375 tcx.mk_fn_def(def_id, substs)
1377 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1378 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1381 Node::Ctor(&ref def) | Node::Variant(hir::Variant { data: ref def, .. }) => match *def {
1382 VariantData::Unit(..) | VariantData::Struct(..) => {
1383 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1385 VariantData::Tuple(..) => {
1386 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1387 tcx.mk_fn_def(def_id, substs)
1391 Node::Field(field) => icx.to_ty(&field.ty),
1393 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) => {
1395 return tcx.typeck_tables_of(def_id).node_type(hir_id);
1398 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1399 tcx.mk_closure(def_id, substs)
1402 Node::AnonConst(_) => {
1403 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1405 Node::Ty(&hir::Ty { kind: hir::TyKind::Array(_, ref constant), .. })
1406 | Node::Ty(&hir::Ty { kind: hir::TyKind::Typeof(ref constant), .. })
1407 | Node::Expr(&hir::Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1408 if constant.hir_id == hir_id =>
1413 Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => {
1414 tcx.adt_def(tcx.hir().get_parent_did(hir_id)).repr.discr_type().to_ty(tcx)
1417 Node::Ty(&hir::Ty { kind: hir::TyKind::Path(_), .. })
1418 | Node::Expr(&hir::Expr { kind: ExprKind::Struct(..), .. })
1419 | Node::Expr(&hir::Expr { kind: ExprKind::Path(_), .. })
1420 | Node::TraitRef(..) => {
1421 let path = match parent_node {
1423 kind: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1426 | Node::Expr(&hir::Expr {
1427 kind: ExprKind::Path(QPath::Resolved(_, ref path)),
1429 }) => Some(&**path),
1430 Node::Expr(&hir::Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
1431 if let QPath::Resolved(_, ref path) = **path {
1437 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
1441 if let Some(path) = path {
1442 let arg_index = path
1445 .filter_map(|seg| seg.args.as_ref())
1446 .map(|generic_args| generic_args.args.as_ref())
1449 .filter(|arg| arg.is_const())
1451 .filter(|(_, arg)| arg.id() == hir_id)
1452 .map(|(index, _)| index)
1455 .unwrap_or_else(|| {
1456 bug!("no arg matching AnonConst in path");
1459 // We've encountered an `AnonConst` in some path, so we need to
1460 // figure out which generic parameter it corresponds to and return
1461 // the relevant type.
1462 let generics = match path.res {
1463 Res::Def(DefKind::Ctor(..), def_id) => {
1464 tcx.generics_of(tcx.parent(def_id).unwrap())
1466 Res::Def(_, def_id) => tcx.generics_of(def_id),
1467 Res::Err => return tcx.types.err,
1469 tcx.sess.delay_span_bug(
1471 &format!("unexpected const parent path def {:?}", res,),
1473 return tcx.types.err;
1481 if let ty::GenericParamDefKind::Const = param.kind {
1488 .map(|param| tcx.type_of(param.def_id))
1489 // This is no generic parameter associated with the arg. This is
1490 // probably from an extra arg where one is not needed.
1491 .unwrap_or(tcx.types.err)
1493 tcx.sess.delay_span_bug(
1495 &format!("unexpected const parent path {:?}", parent_node,),
1497 return tcx.types.err;
1502 tcx.sess.delay_span_bug(
1504 &format!("unexpected const parent in type_of_def_id(): {:?}", x),
1511 Node::GenericParam(param) => match ¶m.kind {
1512 hir::GenericParamKind::Type { default: Some(ref ty), .. } => icx.to_ty(ty),
1513 hir::GenericParamKind::Const { ty: ref hir_ty, .. } => {
1514 let ty = icx.to_ty(hir_ty);
1515 if !tcx.features().const_compare_raw_pointers {
1516 let err = match ty.peel_refs().kind {
1517 ty::FnPtr(_) => Some("function pointers"),
1518 ty::RawPtr(_) => Some("raw pointers"),
1521 if let Some(unsupported_type) = err {
1522 feature_gate::feature_err(
1523 &tcx.sess.parse_sess,
1524 sym::const_compare_raw_pointers,
1527 "using {} as const generic parameters is unstable",
1534 if traits::search_for_structural_match_violation(param.hir_id, param.span, tcx, ty)
1541 "the types of const generic parameters must derive `PartialEq` and `Eq`",
1545 format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
1551 x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
1555 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1560 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1561 use rustc_hir::{ImplItem, Item, TraitItem};
1563 debug!("find_opaque_ty_constraints({:?})", def_id);
1565 struct ConstraintLocator<'tcx> {
1568 // (first found type span, actual type, mapping from the opaque type's generic
1569 // parameters to the concrete type's generic parameters)
1571 // The mapping is an index for each use site of a generic parameter in the concrete type
1573 // The indices index into the generic parameters on the opaque type.
1574 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1577 impl ConstraintLocator<'tcx> {
1578 fn check(&mut self, def_id: DefId) {
1579 // Don't try to check items that cannot possibly constrain the type.
1580 if !self.tcx.has_typeck_tables(def_id) {
1582 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1583 self.def_id, def_id,
1587 let ty = self.tcx.typeck_tables_of(def_id).concrete_opaque_types.get(&self.def_id);
1588 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1590 "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1591 self.def_id, def_id, ty,
1594 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1595 let span = self.tcx.def_span(def_id);
1596 // used to quickly look up the position of a generic parameter
1597 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1598 // Skipping binder is ok, since we only use this to find generic parameters and
1600 for (idx, subst) in substs.iter().enumerate() {
1601 if let GenericArgKind::Type(ty) = subst.unpack() {
1602 if let ty::Param(p) = ty.kind {
1603 if index_map.insert(p, idx).is_some() {
1604 // There was already an entry for `p`, meaning a generic parameter
1606 self.tcx.sess.span_err(
1609 "defining opaque type use restricts opaque \
1610 type by using the generic parameter `{}` twice",
1617 self.tcx.sess.delay_span_bug(
1620 "non-defining opaque ty use in defining scope: {:?}, {:?}",
1621 concrete_type, substs,
1627 // Compute the index within the opaque type for each generic parameter used in
1628 // the concrete type.
1629 let indices = concrete_type
1630 .subst(self.tcx, substs)
1632 .filter_map(|t| match &t.kind {
1633 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1637 let is_param = |ty: Ty<'_>| match ty.kind {
1638 ty::Param(_) => true,
1641 let bad_substs: Vec<_> =
1642 substs.types().enumerate().filter(|(_, ty)| !is_param(ty)).collect();
1643 if !bad_substs.is_empty() {
1644 let identity_substs = InternalSubsts::identity_for_item(self.tcx, self.def_id);
1645 for (i, bad_subst) in bad_substs {
1646 self.tcx.sess.span_err(
1649 "defining opaque type use does not fully define opaque type: \
1650 generic parameter `{}` is specified as concrete type `{}`",
1651 identity_substs.type_at(i),
1656 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1657 let mut ty = concrete_type.walk().fuse();
1658 let mut p_ty = prev_ty.walk().fuse();
1659 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.kind, &p.kind) {
1660 // Type parameters are equal to any other type parameter for the purpose of
1661 // concrete type equality, as it is possible to obtain the same type just
1662 // by passing matching parameters to a function.
1663 (ty::Param(_), ty::Param(_)) => true,
1666 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1667 debug!("find_opaque_ty_constraints: span={:?}", span);
1668 // Found different concrete types for the opaque type.
1669 let mut err = self.tcx.sess.struct_span_err(
1671 "concrete type differs from previous defining opaque type use",
1675 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1677 err.span_note(prev_span, "previous use here");
1679 } else if indices != *prev_indices {
1680 // Found "same" concrete types, but the generic parameter order differs.
1681 let mut err = self.tcx.sess.struct_span_err(
1683 "concrete type's generic parameters differ from previous defining use",
1685 use std::fmt::Write;
1686 let mut s = String::new();
1687 write!(s, "expected [").unwrap();
1688 let list = |s: &mut String, indices: &Vec<usize>| {
1689 let mut indices = indices.iter().cloned();
1690 if let Some(first) = indices.next() {
1691 write!(s, "`{}`", substs[first]).unwrap();
1693 write!(s, ", `{}`", substs[i]).unwrap();
1697 list(&mut s, prev_indices);
1698 write!(s, "], got [").unwrap();
1699 list(&mut s, &indices);
1700 write!(s, "]").unwrap();
1701 err.span_label(span, s);
1702 err.span_note(prev_span, "previous use here");
1706 self.found = Some((span, concrete_type, indices));
1710 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
1711 self.def_id, def_id,
1717 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1718 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1719 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1721 fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
1722 debug!("find_existential_constraints: visiting {:?}", it);
1723 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1724 // The opaque type itself or its children are not within its reveal scope.
1725 if def_id != self.def_id {
1727 intravisit::walk_item(self, it);
1730 fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
1731 debug!("find_existential_constraints: visiting {:?}", it);
1732 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1733 // The opaque type itself or its children are not within its reveal scope.
1734 if def_id != self.def_id {
1736 intravisit::walk_impl_item(self, it);
1739 fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
1740 debug!("find_existential_constraints: visiting {:?}", it);
1741 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1743 intravisit::walk_trait_item(self, it);
1747 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1748 let scope = tcx.hir().get_defining_scope(hir_id);
1749 let mut locator = ConstraintLocator { def_id, tcx, found: None };
1751 debug!("find_opaque_ty_constraints: scope={:?}", scope);
1753 if scope == hir::CRATE_HIR_ID {
1754 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1756 debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
1757 match tcx.hir().get(scope) {
1758 // We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
1759 // This allows our visitor to process the defining item itself, causing
1760 // it to pick up any 'sibling' defining uses.
1762 // For example, this code:
1765 // type Blah = impl Debug;
1766 // let my_closure = || -> Blah { true };
1770 // requires us to explicitly process `foo()` in order
1771 // to notice the defining usage of `Blah`.
1772 Node::Item(ref it) => locator.visit_item(it),
1773 Node::ImplItem(ref it) => locator.visit_impl_item(it),
1774 Node::TraitItem(ref it) => locator.visit_trait_item(it),
1775 other => bug!("{:?} is not a valid scope for an opaque type item", other),
1779 match locator.found {
1780 Some((_, ty, _)) => ty,
1782 let span = tcx.def_span(def_id);
1783 tcx.sess.span_err(span, "could not find defining uses");
1789 /// Whether `ty` is a type with `_` placeholders that can be infered. Used in diagnostics only to
1790 /// use inference to provide suggestions for the appropriate type if possible.
1791 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1793 hir::TyKind::Infer => true,
1794 hir::TyKind::Slice(ty) | hir::TyKind::Array(ty, _) => is_suggestable_infer_ty(ty),
1795 hir::TyKind::Tup(tys) => tys.iter().any(|ty| is_suggestable_infer_ty(ty)),
1800 pub fn get_infer_ret_ty(output: &'hir hir::FunctionRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1801 if let hir::FunctionRetTy::Return(ref ty) = output {
1802 if is_suggestable_infer_ty(ty) {
1809 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1810 use rustc_hir::Node::*;
1813 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1815 let icx = ItemCtxt::new(tcx, def_id);
1817 match tcx.hir().get(hir_id) {
1818 TraitItem(hir::TraitItem {
1819 kind: TraitItemKind::Method(sig, TraitMethod::Provided(_)),
1824 | ImplItem(hir::ImplItem { kind: ImplItemKind::Method(sig, _), ident, generics, .. })
1825 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1826 match get_infer_ret_ty(&sig.decl.output) {
1828 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1829 let mut visitor = PlaceholderHirTyCollector::default();
1830 visitor.visit_ty(ty);
1831 let mut diag = bad_placeholder_type(tcx, visitor.0);
1832 let ret_ty = fn_sig.output();
1833 if ret_ty != tcx.types.err {
1834 diag.span_suggestion(
1836 "replace with the correct return type",
1838 Applicability::MaybeIncorrect,
1842 ty::Binder::bind(fn_sig)
1844 None => AstConv::ty_of_fn(
1846 sig.header.unsafety,
1849 &generics.params[..],
1855 TraitItem(hir::TraitItem {
1856 kind: TraitItemKind::Method(FnSig { header, decl }, _),
1860 }) => AstConv::ty_of_fn(
1865 &generics.params[..],
1869 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(ref fn_decl, _, _), .. }) => {
1870 let abi = tcx.hir().get_foreign_abi(hir_id);
1871 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1874 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1875 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1877 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1878 ty::Binder::bind(tcx.mk_fn_sig(
1882 hir::Unsafety::Normal,
1887 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1888 // Closure signatures are not like other function
1889 // signatures and cannot be accessed through `fn_sig`. For
1890 // example, a closure signature excludes the `self`
1891 // argument. In any case they are embedded within the
1892 // closure type as part of the `ClosureSubsts`.
1895 // the signature of a closure, you should use the
1896 // `closure_sig` method on the `ClosureSubsts`:
1898 // closure_substs.sig(def_id, tcx)
1900 // or, inside of an inference context, you can use
1902 // infcx.closure_sig(def_id, closure_substs)
1903 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1907 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1912 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1913 let icx = ItemCtxt::new(tcx, def_id);
1915 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1916 match tcx.hir().expect_item(hir_id).kind {
1917 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1918 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1919 let selfty = tcx.type_of(def_id);
1920 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1927 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1928 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1929 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1930 let item = tcx.hir().expect_item(hir_id);
1932 hir::ItemKind::Impl(_, hir::ImplPolarity::Negative, ..) => {
1933 if is_rustc_reservation {
1934 tcx.sess.span_err(item.span, "reservation impls can't be negative");
1936 ty::ImplPolarity::Negative
1938 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, None, _, _) => {
1939 if is_rustc_reservation {
1940 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1942 ty::ImplPolarity::Positive
1944 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, Some(_tr), _, _) => {
1945 if is_rustc_reservation {
1946 ty::ImplPolarity::Reservation
1948 ty::ImplPolarity::Positive
1951 ref item => bug!("impl_polarity: {:?} not an impl", item),
1955 /// Returns the early-bound lifetimes declared in this generics
1956 /// listing. For anything other than fns/methods, this is just all
1957 /// the lifetimes that are declared. For fns or methods, we have to
1958 /// screen out those that do not appear in any where-clauses etc using
1959 /// `resolve_lifetime::early_bound_lifetimes`.
1960 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1962 generics: &'a hir::Generics<'a>,
1963 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1964 generics.params.iter().filter(move |param| match param.kind {
1965 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1970 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1971 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1972 /// inferred constraints concerning which regions outlive other regions.
1973 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1974 debug!("predicates_defined_on({:?})", def_id);
1975 let mut result = tcx.explicit_predicates_of(def_id);
1976 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1977 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1978 if !inferred_outlives.is_empty() {
1980 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1981 def_id, inferred_outlives,
1983 if result.predicates.is_empty() {
1984 result.predicates = inferred_outlives;
1986 result.predicates = tcx
1988 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1991 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1995 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1996 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1997 /// `Self: Trait` predicates for traits.
1998 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1999 let mut result = tcx.predicates_defined_on(def_id);
2001 if tcx.is_trait(def_id) {
2002 // For traits, add `Self: Trait` predicate. This is
2003 // not part of the predicates that a user writes, but it
2004 // is something that one must prove in order to invoke a
2005 // method or project an associated type.
2007 // In the chalk setup, this predicate is not part of the
2008 // "predicates" for a trait item. But it is useful in
2009 // rustc because if you directly (e.g.) invoke a trait
2010 // method like `Trait::method(...)`, you must naturally
2011 // prove that the trait applies to the types that were
2012 // used, and adding the predicate into this list ensures
2013 // that this is done.
2014 let span = tcx.def_span(def_id);
2016 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2017 ty::TraitRef::identity(tcx, def_id).to_predicate(),
2021 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2025 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2026 /// N.B., this does not include any implied/inferred constraints.
2027 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2028 use rustc_data_structures::fx::FxHashSet;
2031 debug!("explicit_predicates_of(def_id={:?})", def_id);
2033 /// A data structure with unique elements, which preserves order of insertion.
2034 /// Preserving the order of insertion is important here so as not to break
2035 /// compile-fail UI tests.
2036 // FIXME(eddyb) just use `IndexSet` from `indexmap`.
2037 struct UniquePredicates<'tcx> {
2038 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
2039 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
2042 impl<'tcx> UniquePredicates<'tcx> {
2044 UniquePredicates { predicates: vec![], uniques: FxHashSet::default() }
2047 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
2048 if self.uniques.insert(value) {
2049 self.predicates.push(value);
2053 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
2060 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
2061 let node = tcx.hir().get(hir_id);
2063 let mut is_trait = None;
2064 let mut is_default_impl_trait = None;
2066 let icx = ItemCtxt::new(tcx, def_id);
2068 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2070 let mut predicates = UniquePredicates::new();
2072 let ast_generics = match node {
2073 Node::TraitItem(item) => &item.generics,
2075 Node::ImplItem(item) => match item.kind {
2076 ImplItemKind::OpaqueTy(ref bounds) => {
2077 ty::print::with_no_queries(|| {
2078 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2079 let opaque_ty = tcx.mk_opaque(def_id, substs);
2081 "explicit_predicates_of({:?}): created opaque type {:?}",
2085 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2086 let bounds = AstConv::compute_bounds(
2090 SizedByDefault::Yes,
2091 tcx.def_span(def_id),
2094 predicates.extend(bounds.predicates(tcx, opaque_ty));
2098 _ => &item.generics,
2101 Node::Item(item) => {
2103 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
2104 if defaultness.is_default() {
2105 is_default_impl_trait = tcx.impl_trait_ref(def_id);
2109 ItemKind::Fn(.., ref generics, _)
2110 | ItemKind::TyAlias(_, ref generics)
2111 | ItemKind::Enum(_, ref generics)
2112 | ItemKind::Struct(_, ref generics)
2113 | ItemKind::Union(_, ref generics) => generics,
2115 ItemKind::Trait(_, _, ref generics, .., items) => {
2116 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
2119 ItemKind::TraitAlias(ref generics, _) => {
2120 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &[]));
2123 ItemKind::OpaqueTy(OpaqueTy {
2129 let bounds_predicates = ty::print::with_no_queries(|| {
2130 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2131 let opaque_ty = tcx.mk_opaque(def_id, substs);
2133 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2134 let bounds = AstConv::compute_bounds(
2138 SizedByDefault::Yes,
2139 tcx.def_span(def_id),
2142 bounds.predicates(tcx, opaque_ty)
2144 if impl_trait_fn.is_some() {
2146 return ty::GenericPredicates {
2148 predicates: tcx.arena.alloc_from_iter(bounds_predicates),
2151 // named opaque types
2152 predicates.extend(bounds_predicates);
2161 Node::ForeignItem(item) => match item.kind {
2162 ForeignItemKind::Static(..) => NO_GENERICS,
2163 ForeignItemKind::Fn(_, _, ref generics) => generics,
2164 ForeignItemKind::Type => NO_GENERICS,
2170 let generics = tcx.generics_of(def_id);
2171 let parent_count = generics.parent_count as u32;
2172 let has_own_self = generics.has_self && parent_count == 0;
2174 // Below we'll consider the bounds on the type parameters (including `Self`)
2175 // and the explicit where-clauses, but to get the full set of predicates
2176 // on a trait we need to add in the supertrait bounds and bounds found on
2177 // associated types.
2178 if let Some((_trait_ref, _)) = is_trait {
2179 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2182 // In default impls, we can assume that the self type implements
2183 // the trait. So in:
2185 // default impl Foo for Bar { .. }
2187 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2188 // (see below). Recall that a default impl is not itself an impl, but rather a
2189 // set of defaults that can be incorporated into another impl.
2190 if let Some(trait_ref) = is_default_impl_trait {
2191 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2194 // Collect the region predicates that were declared inline as
2195 // well. In the case of parameters declared on a fn or method, we
2196 // have to be careful to only iterate over early-bound regions.
2197 let mut index = parent_count + has_own_self as u32;
2198 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2199 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2200 def_id: tcx.hir().local_def_id(param.hir_id),
2202 name: param.name.ident().name,
2207 GenericParamKind::Lifetime { .. } => {
2208 param.bounds.iter().for_each(|bound| match bound {
2209 hir::GenericBound::Outlives(lt) => {
2210 let bound = AstConv::ast_region_to_region(&icx, <, None);
2211 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2212 predicates.push((outlives.to_predicate(), lt.span));
2221 // Collect the predicates that were written inline by the user on each
2222 // type parameter (e.g., `<T: Foo>`).
2223 for param in ast_generics.params {
2224 if let GenericParamKind::Type { .. } = param.kind {
2225 let name = param.name.ident().name;
2226 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2229 let sized = SizedByDefault::Yes;
2230 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2231 predicates.extend(bounds.predicates(tcx, param_ty));
2235 // Add in the bounds that appear in the where-clause.
2236 let where_clause = &ast_generics.where_clause;
2237 for predicate in where_clause.predicates {
2239 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2240 let ty = icx.to_ty(&bound_pred.bounded_ty);
2242 // Keep the type around in a dummy predicate, in case of no bounds.
2243 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2244 // is still checked for WF.
2245 if bound_pred.bounds.is_empty() {
2246 if let ty::Param(_) = ty.kind {
2247 // This is a `where T:`, which can be in the HIR from the
2248 // transformation that moves `?Sized` to `T`'s declaration.
2249 // We can skip the predicate because type parameters are
2250 // trivially WF, but also we *should*, to avoid exposing
2251 // users who never wrote `where Type:,` themselves, to
2252 // compiler/tooling bugs from not handling WF predicates.
2254 let span = bound_pred.bounded_ty.span;
2255 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2257 ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)),
2263 for bound in bound_pred.bounds.iter() {
2265 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2266 let mut bounds = Bounds::default();
2267 let _ = AstConv::instantiate_poly_trait_ref(
2273 predicates.extend(bounds.predicates(tcx, ty));
2276 &hir::GenericBound::Outlives(ref lifetime) => {
2277 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2278 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2279 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2285 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2286 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2287 predicates.extend(region_pred.bounds.iter().map(|bound| {
2288 let (r2, span) = match bound {
2289 hir::GenericBound::Outlives(lt) => {
2290 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2294 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2296 (ty::Predicate::RegionOutlives(pred), span)
2300 &hir::WherePredicate::EqPredicate(..) => {
2306 // Add predicates from associated type bounds.
2307 if let Some((self_trait_ref, trait_items)) = is_trait {
2308 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2309 associated_item_predicates(tcx, def_id, self_trait_ref, trait_item_ref)
2313 let mut predicates = predicates.predicates;
2315 // Subtle: before we store the predicates into the tcx, we
2316 // sort them so that predicates like `T: Foo<Item=U>` come
2317 // before uses of `U`. This avoids false ambiguity errors
2318 // in trait checking. See `setup_constraining_predicates`
2320 if let Node::Item(&Item { kind: ItemKind::Impl(..), .. }) = node {
2321 let self_ty = tcx.type_of(def_id);
2322 let trait_ref = tcx.impl_trait_ref(def_id);
2323 cgp::setup_constraining_predicates(
2327 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2331 let result = ty::GenericPredicates {
2332 parent: generics.parent,
2333 predicates: tcx.arena.alloc_from_iter(predicates),
2335 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2339 fn associated_item_predicates(
2342 self_trait_ref: ty::TraitRef<'tcx>,
2343 trait_item_ref: &hir::TraitItemRef,
2344 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2345 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2346 let item_def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
2347 let bounds = match trait_item.kind {
2348 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2349 _ => return Vec::new(),
2352 let is_gat = !tcx.generics_of(item_def_id).params.is_empty();
2354 let mut had_error = false;
2356 let mut unimplemented_error = |arg_kind: &str| {
2361 &format!("{}-generic associated types are not yet implemented", arg_kind),
2363 .note("for more information, see https://github.com/rust-lang/rust/issues/44265")
2369 let mk_bound_param = |param: &ty::GenericParamDef, _: &_| {
2371 ty::GenericParamDefKind::Lifetime => tcx
2372 .mk_region(ty::RegionKind::ReLateBound(
2374 ty::BoundRegion::BrNamed(param.def_id, param.name),
2377 // FIXME(generic_associated_types): Use bound types and constants
2378 // once they are handled by the trait system.
2379 ty::GenericParamDefKind::Type { .. } => {
2380 unimplemented_error("type");
2381 tcx.types.err.into()
2383 ty::GenericParamDefKind::Const => {
2384 unimplemented_error("const");
2385 tcx.consts.err.into()
2390 let bound_substs = if is_gat {
2393 // trait X<'a, B, const C: usize> {
2394 // type T<'d, E, const F: usize>: Default;
2397 // We need to create predicates on the trait:
2399 // for<'d, E, const F: usize>
2400 // <Self as X<'a, B, const C: usize>>::T<'d, E, const F: usize>: Sized + Default
2402 // We substitute escaping bound parameters for the generic
2403 // arguments to the associated type which are then bound by
2404 // the `Binder` around the the predicate.
2406 // FIXME(generic_associated_types): Currently only lifetimes are handled.
2407 self_trait_ref.substs.extend_to(tcx, item_def_id, mk_bound_param)
2409 self_trait_ref.substs
2412 let assoc_ty = tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id), bound_substs);
2414 let bounds = AstConv::compute_bounds(
2415 &ItemCtxt::new(tcx, def_id),
2418 SizedByDefault::Yes,
2422 let predicates = bounds.predicates(tcx, assoc_ty);
2425 // We use shifts to get the regions that we're substituting to
2426 // be bound by the binders in the `Predicate`s rather that
2428 let shifted_in = ty::fold::shift_vars(tcx, &predicates, 1);
2429 let substituted = shifted_in.subst(tcx, bound_substs);
2430 ty::fold::shift_out_vars(tcx, &substituted, 1)
2436 /// Converts a specific `GenericBound` from the AST into a set of
2437 /// predicates that apply to the self type. A vector is returned
2438 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2439 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2440 /// and `<T as Bar>::X == i32`).
2441 fn predicates_from_bound<'tcx>(
2442 astconv: &dyn AstConv<'tcx>,
2444 bound: &'tcx hir::GenericBound<'tcx>,
2445 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2447 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2448 let mut bounds = Bounds::default();
2449 let _ = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut bounds);
2450 bounds.predicates(astconv.tcx(), param_ty)
2452 hir::GenericBound::Outlives(ref lifetime) => {
2453 let region = astconv.ast_region_to_region(lifetime, None);
2454 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2455 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2457 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2461 fn compute_sig_of_foreign_fn_decl<'tcx>(
2464 decl: &'tcx hir::FnDecl<'tcx>,
2466 ) -> ty::PolyFnSig<'tcx> {
2467 let unsafety = if abi == abi::Abi::RustIntrinsic {
2468 intrinsic_operation_unsafety(&tcx.item_name(def_id).as_str())
2470 hir::Unsafety::Unsafe
2472 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl, &[], None);
2474 // Feature gate SIMD types in FFI, since I am not sure that the
2475 // ABIs are handled at all correctly. -huonw
2476 if abi != abi::Abi::RustIntrinsic
2477 && abi != abi::Abi::PlatformIntrinsic
2478 && !tcx.features().simd_ffi
2480 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2486 "use of SIMD type `{}` in FFI is highly experimental and \
2487 may result in invalid code",
2488 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2491 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2495 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2498 if let hir::FunctionRetTy::Return(ref ty) = decl.output {
2499 check(&ty, *fty.output().skip_binder())
2506 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2507 match tcx.hir().get_if_local(def_id) {
2508 Some(Node::ForeignItem(..)) => true,
2510 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2514 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2515 match tcx.hir().get_if_local(def_id) {
2516 Some(Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. }))
2517 | Some(Node::ForeignItem(&hir::ForeignItem {
2518 kind: hir::ForeignItemKind::Static(_, mutbl),
2522 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2526 fn from_target_feature(
2529 attr: &ast::Attribute,
2530 whitelist: &FxHashMap<String, Option<Symbol>>,
2531 target_features: &mut Vec<Symbol>,
2533 let list = match attr.meta_item_list() {
2537 let bad_item = |span| {
2538 let msg = "malformed `target_feature` attribute input";
2539 let code = "enable = \"..\"".to_owned();
2541 .struct_span_err(span, &msg)
2542 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2545 let rust_features = tcx.features();
2547 // Only `enable = ...` is accepted in the meta-item list.
2548 if !item.check_name(sym::enable) {
2549 bad_item(item.span());
2553 // Must be of the form `enable = "..."` (a string).
2554 let value = match item.value_str() {
2555 Some(value) => value,
2557 bad_item(item.span());
2562 // We allow comma separation to enable multiple features.
2563 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2564 // Only allow whitelisted features per platform.
2565 let feature_gate = match whitelist.get(feature) {
2569 format!("the feature named `{}` is not valid for this target", feature);
2570 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2573 format!("`{}` is not valid for this target", feature),
2575 if feature.starts_with("+") {
2576 let valid = whitelist.contains_key(&feature[1..]);
2578 err.help("consider removing the leading `+` in the feature name");
2586 // Only allow features whose feature gates have been enabled.
2587 let allowed = match feature_gate.as_ref().map(|s| *s) {
2588 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2589 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2590 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2591 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2592 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2593 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2594 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2595 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2596 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2597 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2598 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2599 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2600 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2601 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2602 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2603 Some(name) => bug!("unknown target feature gate {}", name),
2606 if !allowed && id.is_local() {
2607 feature_gate::feature_err(
2608 &tcx.sess.parse_sess,
2609 feature_gate.unwrap(),
2611 &format!("the target feature `{}` is currently unstable", feature),
2615 Some(Symbol::intern(feature))
2620 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2621 use rustc::mir::mono::Linkage::*;
2623 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2624 // applicable to variable declarations and may not really make sense for
2625 // Rust code in the first place but whitelist them anyway and trust that
2626 // the user knows what s/he's doing. Who knows, unanticipated use cases
2627 // may pop up in the future.
2629 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2630 // and don't have to be, LLVM treats them as no-ops.
2632 "appending" => Appending,
2633 "available_externally" => AvailableExternally,
2635 "extern_weak" => ExternalWeak,
2636 "external" => External,
2637 "internal" => Internal,
2638 "linkonce" => LinkOnceAny,
2639 "linkonce_odr" => LinkOnceODR,
2640 "private" => Private,
2642 "weak_odr" => WeakODR,
2644 let span = tcx.hir().span_if_local(def_id);
2645 if let Some(span) = span {
2646 tcx.sess.span_fatal(span, "invalid linkage specified")
2648 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2654 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2655 let attrs = tcx.get_attrs(id);
2657 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2659 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2661 let mut inline_span = None;
2662 let mut link_ordinal_span = None;
2663 for attr in attrs.iter() {
2664 if attr.check_name(sym::cold) {
2665 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2666 } else if attr.check_name(sym::rustc_allocator) {
2667 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2668 } else if attr.check_name(sym::unwind) {
2669 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2670 } else if attr.check_name(sym::ffi_returns_twice) {
2671 if tcx.is_foreign_item(id) {
2672 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2674 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2679 "`#[ffi_returns_twice]` may only be used on foreign functions"
2683 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2684 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2685 } else if attr.check_name(sym::naked) {
2686 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2687 } else if attr.check_name(sym::no_mangle) {
2688 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2689 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2690 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2691 } else if attr.check_name(sym::no_debug) {
2692 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2693 } else if attr.check_name(sym::used) {
2694 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2695 } else if attr.check_name(sym::thread_local) {
2696 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2697 } else if attr.check_name(sym::track_caller) {
2698 if tcx.fn_sig(id).abi() != abi::Abi::Rust {
2699 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2702 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2703 } else if attr.check_name(sym::export_name) {
2704 if let Some(s) = attr.value_str() {
2705 if s.as_str().contains("\0") {
2706 // `#[export_name = ...]` will be converted to a null-terminated string,
2707 // so it may not contain any null characters.
2712 "`export_name` may not contain null characters"
2716 codegen_fn_attrs.export_name = Some(s);
2718 } else if attr.check_name(sym::target_feature) {
2719 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2720 let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
2722 .struct_span_err(attr.span, msg)
2723 .span_label(attr.span, "can only be applied to `unsafe` functions")
2724 .span_label(tcx.def_span(id), "not an `unsafe` function")
2727 from_target_feature(tcx, id, attr, &whitelist, &mut codegen_fn_attrs.target_features);
2728 } else if attr.check_name(sym::linkage) {
2729 if let Some(val) = attr.value_str() {
2730 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2732 } else if attr.check_name(sym::link_section) {
2733 if let Some(val) = attr.value_str() {
2734 if val.as_str().bytes().any(|b| b == 0) {
2736 "illegal null byte in link_section \
2740 tcx.sess.span_err(attr.span, &msg);
2742 codegen_fn_attrs.link_section = Some(val);
2745 } else if attr.check_name(sym::link_name) {
2746 codegen_fn_attrs.link_name = attr.value_str();
2747 } else if attr.check_name(sym::link_ordinal) {
2748 link_ordinal_span = Some(attr.span);
2749 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2750 codegen_fn_attrs.link_ordinal = ordinal;
2755 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2756 if !attr.has_name(sym::inline) {
2759 match attr.meta().map(|i| i.kind) {
2760 Some(MetaItemKind::Word) => {
2764 Some(MetaItemKind::List(ref items)) => {
2766 inline_span = Some(attr.span);
2767 if items.len() != 1 {
2769 tcx.sess.diagnostic(),
2772 "expected one argument"
2776 } else if list_contains_name(&items[..], sym::always) {
2778 } else if list_contains_name(&items[..], sym::never) {
2782 tcx.sess.diagnostic(),
2792 Some(MetaItemKind::NameValue(_)) => ia,
2797 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2798 if !attr.has_name(sym::optimize) {
2801 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
2802 match attr.meta().map(|i| i.kind) {
2803 Some(MetaItemKind::Word) => {
2804 err(attr.span, "expected one argument");
2807 Some(MetaItemKind::List(ref items)) => {
2809 inline_span = Some(attr.span);
2810 if items.len() != 1 {
2811 err(attr.span, "expected one argument");
2813 } else if list_contains_name(&items[..], sym::size) {
2815 } else if list_contains_name(&items[..], sym::speed) {
2818 err(items[0].span(), "invalid argument");
2822 Some(MetaItemKind::NameValue(_)) => ia,
2827 // If a function uses #[target_feature] it can't be inlined into general
2828 // purpose functions as they wouldn't have the right target features
2829 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2832 if codegen_fn_attrs.target_features.len() > 0 {
2833 if codegen_fn_attrs.inline == InlineAttr::Always {
2834 if let Some(span) = inline_span {
2837 "cannot use `#[inline(always)]` with \
2838 `#[target_feature]`",
2844 // Weak lang items have the same semantics as "std internal" symbols in the
2845 // sense that they're preserved through all our LTO passes and only
2846 // strippable by the linker.
2848 // Additionally weak lang items have predetermined symbol names.
2849 if tcx.is_weak_lang_item(id) {
2850 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2852 if let Some(name) = weak_lang_items::link_name(&attrs) {
2853 codegen_fn_attrs.export_name = Some(name);
2854 codegen_fn_attrs.link_name = Some(name);
2856 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2858 // Internal symbols to the standard library all have no_mangle semantics in
2859 // that they have defined symbol names present in the function name. This
2860 // also applies to weak symbols where they all have known symbol names.
2861 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2862 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2868 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
2869 use syntax::ast::{Lit, LitIntType, LitKind};
2870 let meta_item_list = attr.meta_item_list();
2871 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
2872 let sole_meta_list = match meta_item_list {
2873 Some([item]) => item.literal(),
2876 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
2877 if *ordinal <= std::usize::MAX as u128 {
2878 Some(*ordinal as usize)
2880 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
2882 .struct_span_err(attr.span, &msg)
2883 .note("the value may not exceed `std::usize::MAX`")
2889 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
2890 .note("an unsuffixed integer value, e.g., `1`, is expected")
2896 fn check_link_name_xor_ordinal(
2898 codegen_fn_attrs: &CodegenFnAttrs,
2899 inline_span: Option<Span>,
2901 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
2904 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
2905 if let Some(span) = inline_span {
2906 tcx.sess.span_err(span, msg);