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;
36 use syntax::ast::{Ident, MetaItemKind};
37 use syntax::attr::{list_contains_name, mark_used, InlineAttr, OptimizeAttr};
38 use syntax::feature_gate;
39 use syntax::symbol::{kw, sym, Symbol};
40 use syntax_pos::{Span, DUMMY_SP};
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 ///////////////////////////////////////////////////////////////////////////
105 struct CollectItemTypesVisitor<'tcx> {
109 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
110 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
111 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
114 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
115 convert_item(self.tcx, item.hir_id);
116 intravisit::walk_item(self, item);
119 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
120 for param in &generics.params {
122 hir::GenericParamKind::Lifetime { .. } => {}
123 hir::GenericParamKind::Type { default: Some(_), .. } => {
124 let def_id = self.tcx.hir().local_def_id(param.hir_id);
125 self.tcx.type_of(def_id);
127 hir::GenericParamKind::Type { .. } => {}
128 hir::GenericParamKind::Const { .. } => {
129 let def_id = self.tcx.hir().local_def_id(param.hir_id);
130 self.tcx.type_of(def_id);
134 intravisit::walk_generics(self, generics);
137 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
138 if let hir::ExprKind::Closure(..) = expr.kind {
139 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
140 self.tcx.generics_of(def_id);
141 self.tcx.type_of(def_id);
143 intravisit::walk_expr(self, expr);
146 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
147 convert_trait_item(self.tcx, trait_item.hir_id);
148 intravisit::walk_trait_item(self, trait_item);
151 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
152 convert_impl_item(self.tcx, impl_item.hir_id);
153 intravisit::walk_impl_item(self, impl_item);
157 ///////////////////////////////////////////////////////////////////////////
158 // Utility types and common code for the above passes.
160 fn bad_placeholder_type(tcx: TyCtxt<'tcx>, span: Span) -> errors::DiagnosticBuilder<'tcx> {
161 let mut diag = struct_span_err!(
165 "the type placeholder `_` is not allowed within types on item signatures",
167 diag.span_label(span, "not allowed in type signatures");
171 impl ItemCtxt<'tcx> {
172 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
173 ItemCtxt { tcx, item_def_id }
176 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
177 AstConv::ast_ty_to_ty(self, ast_ty)
181 impl AstConv<'tcx> for ItemCtxt<'tcx> {
182 fn tcx(&self) -> TyCtxt<'tcx> {
186 fn item_def_id(&self) -> Option<DefId> {
187 Some(self.item_def_id)
190 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
191 self.tcx.at(span).type_param_predicates((self.item_def_id, def_id))
194 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
198 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
199 bad_placeholder_type(self.tcx(), span).emit();
207 _: Option<&ty::GenericParamDef>,
209 ) -> &'tcx Const<'tcx> {
210 bad_placeholder_type(self.tcx(), span).emit();
212 self.tcx().consts.err
215 fn projected_ty_from_poly_trait_ref(
219 item_segment: &hir::PathSegment<'_>,
220 poly_trait_ref: ty::PolyTraitRef<'tcx>,
222 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
223 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
231 self.tcx().mk_projection(item_def_id, item_substs)
233 // There are no late-bound regions; we can just ignore the binder.
238 "cannot extract an associated type from a higher-ranked trait bound \
245 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
246 // Types in item signatures are not normalized to avoid undue dependencies.
250 fn set_tainted_by_errors(&self) {
251 // There's no obvious place to track this, so just let it go.
254 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
255 // There's no place to record types from signatures?
259 /// Returns the predicates defined on `item_def_id` of the form
260 /// `X: Foo` where `X` is the type parameter `def_id`.
261 fn type_param_predicates(
263 (item_def_id, def_id): (DefId, DefId),
264 ) -> ty::GenericPredicates<'_> {
267 // In the AST, bounds can derive from two places. Either
268 // written inline like `<T: Foo>` or in a where-clause like
271 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
272 let param_owner = tcx.hir().ty_param_owner(param_id);
273 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
274 let generics = tcx.generics_of(param_owner_def_id);
275 let index = generics.param_def_id_to_index[&def_id];
276 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
278 // Don't look for bounds where the type parameter isn't in scope.
280 if item_def_id == param_owner_def_id { None } else { tcx.generics_of(item_def_id).parent };
282 let mut result = parent
284 let icx = ItemCtxt::new(tcx, parent);
285 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
287 .unwrap_or_default();
288 let mut extend = None;
290 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
291 let ast_generics = match tcx.hir().get(item_hir_id) {
292 Node::TraitItem(item) => &item.generics,
294 Node::ImplItem(item) => &item.generics,
296 Node::Item(item) => {
298 ItemKind::Fn(.., ref generics, _)
299 | ItemKind::Impl(_, _, _, ref generics, ..)
300 | ItemKind::TyAlias(_, ref generics)
301 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
302 | ItemKind::Enum(_, ref generics)
303 | ItemKind::Struct(_, ref generics)
304 | ItemKind::Union(_, ref generics) => generics,
305 ItemKind::Trait(_, _, ref generics, ..) => {
306 // Implied `Self: Trait` and supertrait bounds.
307 if param_id == item_hir_id {
308 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
309 extend = Some((identity_trait_ref.to_predicate(), item.span));
317 Node::ForeignItem(item) => match item.kind {
318 ForeignItemKind::Fn(_, _, ref generics) => generics,
325 let icx = ItemCtxt::new(tcx, item_def_id);
326 let extra_predicates = extend.into_iter().chain(
327 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
329 .filter(|(predicate, _)| match predicate {
330 ty::Predicate::Trait(ref data) => data.skip_binder().self_ty().is_param(index),
335 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
339 impl ItemCtxt<'tcx> {
340 /// Finds bounds from `hir::Generics`. This requires scanning through the
341 /// AST. We do this to avoid having to convert *all* the bounds, which
342 /// would create artificial cycles. Instead, we can only convert the
343 /// bounds for a type parameter `X` if `X::Foo` is used.
344 fn type_parameter_bounds_in_generics(
346 ast_generics: &'tcx hir::Generics<'tcx>,
347 param_id: hir::HirId,
349 only_self_bounds: OnlySelfBounds,
350 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
351 let from_ty_params = ast_generics
354 .filter_map(|param| match param.kind {
355 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
358 .flat_map(|bounds| bounds.iter())
359 .flat_map(|b| predicates_from_bound(self, ty, b));
361 let from_where_clauses = ast_generics
365 .filter_map(|wp| match *wp {
366 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
370 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
372 } else if !only_self_bounds.0 {
373 Some(self.to_ty(&bp.bounded_ty))
377 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
379 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
381 from_ty_params.chain(from_where_clauses).collect()
385 /// Tests whether this is the AST for a reference to the type
386 /// parameter with ID `param_id`. We use this so as to avoid running
387 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
388 /// conversion of the type to avoid inducing unnecessary cycles.
389 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
390 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
392 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
393 def_id == tcx.hir().local_def_id(param_id)
402 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::HirId) {
403 let it = tcx.hir().expect_item(item_id);
404 debug!("convert: item {} with id {}", it.ident, it.hir_id);
405 let def_id = tcx.hir().local_def_id(item_id);
407 // These don't define types.
408 hir::ItemKind::ExternCrate(_)
409 | hir::ItemKind::Use(..)
410 | hir::ItemKind::Mod(_)
411 | hir::ItemKind::GlobalAsm(_) => {}
412 hir::ItemKind::ForeignMod(ref foreign_mod) => {
413 for item in foreign_mod.items {
414 let def_id = tcx.hir().local_def_id(item.hir_id);
415 tcx.generics_of(def_id);
417 tcx.predicates_of(def_id);
418 if let hir::ForeignItemKind::Fn(..) = item.kind {
423 hir::ItemKind::Enum(ref enum_definition, _) => {
424 tcx.generics_of(def_id);
426 tcx.predicates_of(def_id);
427 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
429 hir::ItemKind::Impl(..) => {
430 tcx.generics_of(def_id);
432 tcx.impl_trait_ref(def_id);
433 tcx.predicates_of(def_id);
435 hir::ItemKind::Trait(..) => {
436 tcx.generics_of(def_id);
437 tcx.trait_def(def_id);
438 tcx.at(it.span).super_predicates_of(def_id);
439 tcx.predicates_of(def_id);
441 hir::ItemKind::TraitAlias(..) => {
442 tcx.generics_of(def_id);
443 tcx.at(it.span).super_predicates_of(def_id);
444 tcx.predicates_of(def_id);
446 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
447 tcx.generics_of(def_id);
449 tcx.predicates_of(def_id);
451 for f in struct_def.fields() {
452 let def_id = tcx.hir().local_def_id(f.hir_id);
453 tcx.generics_of(def_id);
455 tcx.predicates_of(def_id);
458 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
459 convert_variant_ctor(tcx, ctor_hir_id);
463 // Desugared from `impl Trait`, so visited by the function's return type.
464 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
466 hir::ItemKind::OpaqueTy(..)
467 | hir::ItemKind::TyAlias(..)
468 | hir::ItemKind::Static(..)
469 | hir::ItemKind::Const(..)
470 | hir::ItemKind::Fn(..) => {
471 tcx.generics_of(def_id);
473 tcx.predicates_of(def_id);
474 if let hir::ItemKind::Fn(..) = it.kind {
481 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
482 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
483 let def_id = tcx.hir().local_def_id(trait_item.hir_id);
484 tcx.generics_of(def_id);
486 match trait_item.kind {
487 hir::TraitItemKind::Const(..)
488 | hir::TraitItemKind::Type(_, Some(_))
489 | hir::TraitItemKind::Method(..) => {
491 if let hir::TraitItemKind::Method(..) = trait_item.kind {
496 hir::TraitItemKind::Type(_, None) => {}
499 tcx.predicates_of(def_id);
502 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
503 let def_id = tcx.hir().local_def_id(impl_item_id);
504 tcx.generics_of(def_id);
506 tcx.predicates_of(def_id);
507 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).kind {
512 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
513 let def_id = tcx.hir().local_def_id(ctor_id);
514 tcx.generics_of(def_id);
516 tcx.predicates_of(def_id);
519 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
520 let def = tcx.adt_def(def_id);
521 let repr_type = def.repr.discr_type();
522 let initial = repr_type.initial_discriminant(tcx);
523 let mut prev_discr = None::<Discr<'_>>;
525 // fill the discriminant values and field types
526 for variant in variants {
527 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
529 if let Some(ref e) = variant.disr_expr {
530 let expr_did = tcx.hir().local_def_id(e.hir_id);
531 def.eval_explicit_discr(tcx, expr_did)
532 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
535 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
538 format!("overflowed on value after {}", prev_discr.unwrap()),
541 "explicitly set `{} = {}` if that is desired outcome",
542 variant.ident, wrapped_discr
547 .unwrap_or(wrapped_discr),
550 for f in variant.data.fields() {
551 let def_id = tcx.hir().local_def_id(f.hir_id);
552 tcx.generics_of(def_id);
554 tcx.predicates_of(def_id);
557 // Convert the ctor, if any. This also registers the variant as
559 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
560 convert_variant_ctor(tcx, ctor_hir_id);
567 variant_did: Option<DefId>,
568 ctor_did: Option<DefId>,
570 discr: ty::VariantDiscr,
571 def: &hir::VariantData<'_>,
572 adt_kind: ty::AdtKind,
574 ) -> ty::VariantDef {
575 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
576 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
581 let fid = tcx.hir().local_def_id(f.hir_id);
582 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
583 if let Some(prev_span) = dup_span {
588 "field `{}` is already declared",
591 .span_label(f.span, "field already declared")
592 .span_label(prev_span, format!("`{}` first declared here", f.ident))
595 seen_fields.insert(f.ident.modern(), f.span);
601 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
605 let recovered = match def {
606 hir::VariantData::Struct(_, r) => *r,
616 CtorKind::from_hir(def),
623 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
626 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
627 let item = match tcx.hir().get(hir_id) {
628 Node::Item(item) => item,
632 let repr = ReprOptions::new(tcx, def_id);
633 let (kind, variants) = match item.kind {
634 ItemKind::Enum(ref def, _) => {
635 let mut distance_from_explicit = 0;
640 let variant_did = Some(tcx.hir().local_def_id(v.id));
642 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
644 let discr = if let Some(ref e) = v.disr_expr {
645 distance_from_explicit = 0;
646 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id))
648 ty::VariantDiscr::Relative(distance_from_explicit)
650 distance_from_explicit += 1;
665 (AdtKind::Enum, variants)
667 ItemKind::Struct(ref def, _) => {
668 let variant_did = None;
669 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
671 let variants = std::iter::once(convert_variant(
676 ty::VariantDiscr::Relative(0),
683 (AdtKind::Struct, variants)
685 ItemKind::Union(ref def, _) => {
686 let variant_did = None;
687 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
689 let variants = std::iter::once(convert_variant(
694 ty::VariantDiscr::Relative(0),
701 (AdtKind::Union, variants)
705 tcx.alloc_adt_def(def_id, kind, variants, repr)
708 /// Ensures that the super-predicates of the trait with a `DefId`
709 /// of `trait_def_id` are converted and stored. This also ensures that
710 /// the transitive super-predicates are converted.
711 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
712 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
713 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
715 let item = match tcx.hir().get(trait_hir_id) {
716 Node::Item(item) => item,
717 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
720 let (generics, bounds) = match item.kind {
721 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
722 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
723 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
726 let icx = ItemCtxt::new(tcx, trait_def_id);
728 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
729 let self_param_ty = tcx.types.self_param;
731 AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
733 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
735 // Convert any explicit superbounds in the where-clause,
736 // e.g., `trait Foo where Self: Bar`.
737 // In the case of trait aliases, however, we include all bounds in the where-clause,
738 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
739 // as one of its "superpredicates".
740 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
741 let superbounds2 = icx.type_parameter_bounds_in_generics(
745 OnlySelfBounds(!is_trait_alias),
748 // Combine the two lists to form the complete set of superbounds:
749 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
751 // Now require that immediate supertraits are converted,
752 // which will, in turn, reach indirect supertraits.
753 for &(pred, span) in superbounds {
754 debug!("superbound: {:?}", pred);
755 if let ty::Predicate::Trait(bound) = pred {
756 tcx.at(span).super_predicates_of(bound.def_id());
760 ty::GenericPredicates { parent: None, predicates: superbounds }
763 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
764 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
765 let item = tcx.hir().expect_item(hir_id);
767 let (is_auto, unsafety) = match item.kind {
768 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
769 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
770 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
773 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
774 if paren_sugar && !tcx.features().unboxed_closures {
775 let mut err = tcx.sess.struct_span_err(
777 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
778 which traits can use parenthetical notation",
782 "add `#![feature(unboxed_closures)]` to \
783 the crate attributes to use it"
788 let is_marker = tcx.has_attr(def_id, sym::marker);
789 let def_path_hash = tcx.def_path_hash(def_id);
790 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
794 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
795 struct LateBoundRegionsDetector<'tcx> {
797 outer_index: ty::DebruijnIndex,
798 has_late_bound_regions: Option<Span>,
801 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
802 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
803 NestedVisitorMap::None
806 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
807 if self.has_late_bound_regions.is_some() {
811 hir::TyKind::BareFn(..) => {
812 self.outer_index.shift_in(1);
813 intravisit::walk_ty(self, ty);
814 self.outer_index.shift_out(1);
816 _ => intravisit::walk_ty(self, ty),
820 fn visit_poly_trait_ref(
822 tr: &'tcx hir::PolyTraitRef<'tcx>,
823 m: hir::TraitBoundModifier,
825 if self.has_late_bound_regions.is_some() {
828 self.outer_index.shift_in(1);
829 intravisit::walk_poly_trait_ref(self, tr, m);
830 self.outer_index.shift_out(1);
833 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
834 if self.has_late_bound_regions.is_some() {
838 match self.tcx.named_region(lt.hir_id) {
839 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
840 Some(rl::Region::LateBound(debruijn, _, _))
841 | Some(rl::Region::LateBoundAnon(debruijn, _))
842 if debruijn < self.outer_index => {}
843 Some(rl::Region::LateBound(..))
844 | Some(rl::Region::LateBoundAnon(..))
845 | Some(rl::Region::Free(..))
847 self.has_late_bound_regions = Some(lt.span);
853 fn has_late_bound_regions<'tcx>(
855 generics: &'tcx hir::Generics<'tcx>,
856 decl: &'tcx hir::FnDecl<'tcx>,
858 let mut visitor = LateBoundRegionsDetector {
860 outer_index: ty::INNERMOST,
861 has_late_bound_regions: None,
863 for param in &generics.params {
864 if let GenericParamKind::Lifetime { .. } = param.kind {
865 if tcx.is_late_bound(param.hir_id) {
866 return Some(param.span);
870 visitor.visit_fn_decl(decl);
871 visitor.has_late_bound_regions
875 Node::TraitItem(item) => match item.kind {
876 hir::TraitItemKind::Method(ref sig, _) => {
877 has_late_bound_regions(tcx, &item.generics, &sig.decl)
881 Node::ImplItem(item) => match item.kind {
882 hir::ImplItemKind::Method(ref sig, _) => {
883 has_late_bound_regions(tcx, &item.generics, &sig.decl)
887 Node::ForeignItem(item) => match item.kind {
888 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
889 has_late_bound_regions(tcx, generics, fn_decl)
893 Node::Item(item) => match item.kind {
894 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
895 has_late_bound_regions(tcx, generics, &sig.decl)
903 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
906 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
908 let node = tcx.hir().get(hir_id);
909 let parent_def_id = match node {
914 | Node::Field(_) => {
915 let parent_id = tcx.hir().get_parent_item(hir_id);
916 Some(tcx.hir().local_def_id(parent_id))
918 // FIXME(#43408) enable this always when we get lazy normalization.
919 Node::AnonConst(_) => {
920 // HACK(eddyb) this provides the correct generics when
921 // `feature(const_generics)` is enabled, so that const expressions
922 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
923 if tcx.features().const_generics {
924 let parent_id = tcx.hir().get_parent_item(hir_id);
925 Some(tcx.hir().local_def_id(parent_id))
930 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
931 Some(tcx.closure_base_def_id(def_id))
933 Node::Item(item) => match item.kind {
934 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => impl_trait_fn,
940 let mut opt_self = None;
941 let mut allow_defaults = false;
943 let no_generics = hir::Generics::empty();
944 let ast_generics = match node {
945 Node::TraitItem(item) => &item.generics,
947 Node::ImplItem(item) => &item.generics,
949 Node::Item(item) => {
951 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
955 ItemKind::TyAlias(_, ref generics)
956 | ItemKind::Enum(_, ref generics)
957 | ItemKind::Struct(_, ref generics)
958 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
959 | ItemKind::Union(_, ref generics) => {
960 allow_defaults = true;
964 ItemKind::Trait(_, _, ref generics, ..)
965 | ItemKind::TraitAlias(ref generics, ..) => {
966 // Add in the self type parameter.
968 // Something of a hack: use the node id for the trait, also as
969 // the node id for the Self type parameter.
970 let param_id = item.hir_id;
972 opt_self = Some(ty::GenericParamDef {
975 def_id: tcx.hir().local_def_id(param_id),
976 pure_wrt_drop: false,
977 kind: ty::GenericParamDefKind::Type {
979 object_lifetime_default: rl::Set1::Empty,
984 allow_defaults = true;
992 Node::ForeignItem(item) => match item.kind {
993 ForeignItemKind::Static(..) => &no_generics,
994 ForeignItemKind::Fn(_, _, ref generics) => generics,
995 ForeignItemKind::Type => &no_generics,
1001 let has_self = opt_self.is_some();
1002 let mut parent_has_self = false;
1003 let mut own_start = has_self as u32;
1004 let parent_count = parent_def_id.map_or(0, |def_id| {
1005 let generics = tcx.generics_of(def_id);
1006 assert_eq!(has_self, false);
1007 parent_has_self = generics.has_self;
1008 own_start = generics.count() as u32;
1009 generics.parent_count + generics.params.len()
1012 let mut params: Vec<_> = opt_self.into_iter().collect();
1014 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1015 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1016 name: param.name.ident().name,
1017 index: own_start + i as u32,
1018 def_id: tcx.hir().local_def_id(param.hir_id),
1019 pure_wrt_drop: param.pure_wrt_drop,
1020 kind: ty::GenericParamDefKind::Lifetime,
1023 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1025 // Now create the real type parameters.
1026 let type_start = own_start - has_self as u32 + params.len() as u32;
1028 params.extend(ast_generics.params.iter().filter_map(|param| {
1029 let kind = match param.kind {
1030 GenericParamKind::Type { ref default, synthetic, .. } => {
1031 if !allow_defaults && default.is_some() {
1032 if !tcx.features().default_type_parameter_fallback {
1034 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1038 "defaults for type parameters are only allowed in \
1039 `struct`, `enum`, `type`, or `trait` definitions."
1045 ty::GenericParamDefKind::Type {
1046 has_default: default.is_some(),
1047 object_lifetime_default: object_lifetime_defaults
1049 .map_or(rl::Set1::Empty, |o| o[i]),
1053 GenericParamKind::Const { .. } => ty::GenericParamDefKind::Const,
1057 let param_def = ty::GenericParamDef {
1058 index: type_start + i as u32,
1059 name: param.name.ident().name,
1060 def_id: tcx.hir().local_def_id(param.hir_id),
1061 pure_wrt_drop: param.pure_wrt_drop,
1068 // provide junk type parameter defs - the only place that
1069 // cares about anything but the length is instantiation,
1070 // and we don't do that for closures.
1071 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1072 let dummy_args = if gen.is_some() {
1073 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1075 &["<closure_kind>", "<closure_signature>"][..]
1078 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1079 index: type_start + i as u32,
1080 name: Symbol::intern(arg),
1082 pure_wrt_drop: false,
1083 kind: ty::GenericParamDefKind::Type {
1085 object_lifetime_default: rl::Set1::Empty,
1090 if let Some(upvars) = tcx.upvars(def_id) {
1091 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1092 ty::GenericParamDef {
1093 index: type_start + i,
1094 name: Symbol::intern("<upvar>"),
1096 pure_wrt_drop: false,
1097 kind: ty::GenericParamDefKind::Type {
1099 object_lifetime_default: rl::Set1::Empty,
1107 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1109 tcx.arena.alloc(ty::Generics {
1110 parent: parent_def_id,
1113 param_def_id_to_index,
1114 has_self: has_self || parent_has_self,
1115 has_late_bound_regions: has_late_bound_regions(tcx, node),
1119 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
1124 "associated types are not yet supported in inherent impls (see #8995)"
1128 fn infer_placeholder_type(
1131 body_id: hir::BodyId,
1135 let ty = tcx.typeck_tables_of(def_id).node_type(body_id.hir_id);
1137 // If this came from a free `const` or `static mut?` item,
1138 // then the user may have written e.g. `const A = 42;`.
1139 // In this case, the parser has stashed a diagnostic for
1140 // us to improve in typeck so we do that now.
1141 match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
1143 // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
1144 // We are typeck and have the real type, so remove that and suggest the actual type.
1145 err.suggestions.clear();
1146 err.span_suggestion(
1148 "provide a type for the item",
1149 format!("{}: {}", item_ident, ty),
1150 Applicability::MachineApplicable,
1155 let mut diag = bad_placeholder_type(tcx, span);
1156 if ty != tcx.types.err {
1157 diag.span_suggestion(
1159 "replace `_` with the correct type",
1161 Applicability::MaybeIncorrect,
1171 fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1174 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1176 let icx = ItemCtxt::new(tcx, def_id);
1178 match tcx.hir().get(hir_id) {
1179 Node::TraitItem(item) => match item.kind {
1180 TraitItemKind::Method(..) => {
1181 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1182 tcx.mk_fn_def(def_id, substs)
1184 TraitItemKind::Const(ref ty, body_id) => body_id
1185 .and_then(|body_id| {
1186 if let hir::TyKind::Infer = ty.kind {
1187 Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
1192 .unwrap_or_else(|| icx.to_ty(ty)),
1193 TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1194 TraitItemKind::Type(_, None) => {
1195 span_bug!(item.span, "associated type missing default");
1199 Node::ImplItem(item) => match item.kind {
1200 ImplItemKind::Method(..) => {
1201 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1202 tcx.mk_fn_def(def_id, substs)
1204 ImplItemKind::Const(ref ty, body_id) => {
1205 if let hir::TyKind::Infer = ty.kind {
1206 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1211 ImplItemKind::OpaqueTy(_) => {
1212 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1213 report_assoc_ty_on_inherent_impl(tcx, item.span);
1216 find_opaque_ty_constraints(tcx, def_id)
1218 ImplItemKind::TyAlias(ref ty) => {
1219 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1220 report_assoc_ty_on_inherent_impl(tcx, item.span);
1227 Node::Item(item) => {
1229 ItemKind::Static(ref ty, .., body_id) | ItemKind::Const(ref ty, body_id) => {
1230 if let hir::TyKind::Infer = ty.kind {
1231 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1236 ItemKind::TyAlias(ref ty, _) | ItemKind::Impl(.., ref ty, _) => icx.to_ty(ty),
1237 ItemKind::Fn(..) => {
1238 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1239 tcx.mk_fn_def(def_id, substs)
1241 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1242 let def = tcx.adt_def(def_id);
1243 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1244 tcx.mk_adt(def, substs)
1246 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: None, .. }) => {
1247 find_opaque_ty_constraints(tcx, def_id)
1249 // Opaque types desugared from `impl Trait`.
1250 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(owner), .. }) => {
1251 tcx.typeck_tables_of(owner)
1252 .concrete_opaque_types
1254 .map(|opaque| opaque.concrete_type)
1255 .unwrap_or_else(|| {
1256 // This can occur if some error in the
1257 // owner fn prevented us from populating
1258 // the `concrete_opaque_types` table.
1259 tcx.sess.delay_span_bug(
1262 "owner {:?} has no opaque type for {:?} in its tables",
1270 | ItemKind::TraitAlias(..)
1272 | ItemKind::ForeignMod(..)
1273 | ItemKind::GlobalAsm(..)
1274 | ItemKind::ExternCrate(..)
1275 | ItemKind::Use(..) => {
1278 "compute_type_of_item: unexpected item type: {:?}",
1285 Node::ForeignItem(foreign_item) => match foreign_item.kind {
1286 ForeignItemKind::Fn(..) => {
1287 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1288 tcx.mk_fn_def(def_id, substs)
1290 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1291 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1294 Node::Ctor(&ref def) | Node::Variant(hir::Variant { data: ref def, .. }) => match *def {
1295 VariantData::Unit(..) | VariantData::Struct(..) => {
1296 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1298 VariantData::Tuple(..) => {
1299 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1300 tcx.mk_fn_def(def_id, substs)
1304 Node::Field(field) => icx.to_ty(&field.ty),
1306 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) => {
1308 return tcx.typeck_tables_of(def_id).node_type(hir_id);
1311 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1312 tcx.mk_closure(def_id, substs)
1315 Node::AnonConst(_) => {
1316 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1318 Node::Ty(&hir::Ty { kind: hir::TyKind::Array(_, ref constant), .. })
1319 | Node::Ty(&hir::Ty { kind: hir::TyKind::Typeof(ref constant), .. })
1320 | Node::Expr(&hir::Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1321 if constant.hir_id == hir_id =>
1326 Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => {
1327 tcx.adt_def(tcx.hir().get_parent_did(hir_id)).repr.discr_type().to_ty(tcx)
1330 Node::Ty(&hir::Ty { kind: hir::TyKind::Path(_), .. })
1331 | Node::Expr(&hir::Expr { kind: ExprKind::Struct(..), .. })
1332 | Node::Expr(&hir::Expr { kind: ExprKind::Path(_), .. })
1333 | Node::TraitRef(..) => {
1334 let path = match parent_node {
1336 kind: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1339 | Node::Expr(&hir::Expr {
1340 kind: ExprKind::Path(QPath::Resolved(_, ref path)),
1342 }) => Some(&**path),
1343 Node::Expr(&hir::Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
1344 if let QPath::Resolved(_, ref path) = **path {
1350 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
1354 if let Some(path) = path {
1355 let arg_index = path
1358 .filter_map(|seg| seg.args.as_ref())
1359 .map(|generic_args| generic_args.args.as_ref())
1362 .filter(|arg| arg.is_const())
1364 .filter(|(_, arg)| arg.id() == hir_id)
1365 .map(|(index, _)| index)
1368 .unwrap_or_else(|| {
1369 bug!("no arg matching AnonConst in path");
1372 // We've encountered an `AnonConst` in some path, so we need to
1373 // figure out which generic parameter it corresponds to and return
1374 // the relevant type.
1375 let generics = match path.res {
1376 Res::Def(DefKind::Ctor(..), def_id) => {
1377 tcx.generics_of(tcx.parent(def_id).unwrap())
1379 Res::Def(_, def_id) => tcx.generics_of(def_id),
1380 Res::Err => return tcx.types.err,
1382 tcx.sess.delay_span_bug(
1384 &format!("unexpected const parent path def {:?}", res,),
1386 return tcx.types.err;
1394 if let ty::GenericParamDefKind::Const = param.kind {
1401 .map(|param| tcx.type_of(param.def_id))
1402 // This is no generic parameter associated with the arg. This is
1403 // probably from an extra arg where one is not needed.
1404 .unwrap_or(tcx.types.err)
1406 tcx.sess.delay_span_bug(
1408 &format!("unexpected const parent path {:?}", parent_node,),
1410 return tcx.types.err;
1415 tcx.sess.delay_span_bug(
1417 &format!("unexpected const parent in type_of_def_id(): {:?}", x),
1424 Node::GenericParam(param) => {
1426 hir::GenericParamKind::Type { default: Some(ref ty), .. } => icx.to_ty(ty),
1427 hir::GenericParamKind::Const { ty: ref hir_ty, .. } => {
1428 let ty = icx.to_ty(hir_ty);
1429 if !tcx.features().const_compare_raw_pointers {
1430 let err = match ty.peel_refs().kind {
1431 ty::FnPtr(_) => Some("function pointers"),
1432 ty::RawPtr(_) => Some("raw pointers"),
1435 if let Some(unsupported_type) = err {
1436 feature_gate::feature_err(
1437 &tcx.sess.parse_sess,
1438 sym::const_compare_raw_pointers,
1441 "using {} as const generic parameters is unstable",
1448 if ty::search_for_structural_match_violation(param.hir_id, param.span, tcx, ty)
1455 "the types of const generic parameters must derive `PartialEq` and `Eq`",
1458 format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
1463 x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
1468 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1473 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1474 use rustc::hir::{ImplItem, Item, TraitItem};
1476 debug!("find_opaque_ty_constraints({:?})", def_id);
1478 struct ConstraintLocator<'tcx> {
1481 // (first found type span, actual type, mapping from the opaque type's generic
1482 // parameters to the concrete type's generic parameters)
1484 // The mapping is an index for each use site of a generic parameter in the concrete type
1486 // The indices index into the generic parameters on the opaque type.
1487 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1490 impl ConstraintLocator<'tcx> {
1491 fn check(&mut self, def_id: DefId) {
1492 // Don't try to check items that cannot possibly constrain the type.
1493 if !self.tcx.has_typeck_tables(def_id) {
1495 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1496 self.def_id, def_id,
1500 let ty = self.tcx.typeck_tables_of(def_id).concrete_opaque_types.get(&self.def_id);
1501 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1503 "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1504 self.def_id, def_id, ty,
1507 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1508 let span = self.tcx.def_span(def_id);
1509 // used to quickly look up the position of a generic parameter
1510 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1511 // Skipping binder is ok, since we only use this to find generic parameters and
1513 for (idx, subst) in substs.iter().enumerate() {
1514 if let GenericArgKind::Type(ty) = subst.unpack() {
1515 if let ty::Param(p) = ty.kind {
1516 if index_map.insert(p, idx).is_some() {
1517 // There was already an entry for `p`, meaning a generic parameter
1519 self.tcx.sess.span_err(
1522 "defining opaque type use restricts opaque \
1523 type by using the generic parameter `{}` twice",
1530 self.tcx.sess.delay_span_bug(
1533 "non-defining opaque ty use in defining scope: {:?}, {:?}",
1534 concrete_type, substs,
1540 // Compute the index within the opaque type for each generic parameter used in
1541 // the concrete type.
1542 let indices = concrete_type
1543 .subst(self.tcx, substs)
1545 .filter_map(|t| match &t.kind {
1546 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1550 let is_param = |ty: Ty<'_>| match ty.kind {
1551 ty::Param(_) => true,
1554 let bad_substs: Vec<_> =
1555 substs.types().enumerate().filter(|(_, ty)| !is_param(ty)).collect();
1556 if !bad_substs.is_empty() {
1557 let identity_substs = InternalSubsts::identity_for_item(self.tcx, self.def_id);
1558 for (i, bad_subst) in bad_substs {
1559 self.tcx.sess.span_err(
1562 "defining opaque type use does not fully define opaque type: \
1563 generic parameter `{}` is specified as concrete type `{}`",
1564 identity_substs.type_at(i),
1569 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1570 let mut ty = concrete_type.walk().fuse();
1571 let mut p_ty = prev_ty.walk().fuse();
1572 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.kind, &p.kind) {
1573 // Type parameters are equal to any other type parameter for the purpose of
1574 // concrete type equality, as it is possible to obtain the same type just
1575 // by passing matching parameters to a function.
1576 (ty::Param(_), ty::Param(_)) => true,
1579 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1580 debug!("find_opaque_ty_constraints: span={:?}", span);
1581 // Found different concrete types for the opaque type.
1582 let mut err = self.tcx.sess.struct_span_err(
1584 "concrete type differs from previous defining opaque type use",
1588 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1590 err.span_note(prev_span, "previous use here");
1592 } else if indices != *prev_indices {
1593 // Found "same" concrete types, but the generic parameter order differs.
1594 let mut err = self.tcx.sess.struct_span_err(
1596 "concrete type's generic parameters differ from previous defining use",
1598 use std::fmt::Write;
1599 let mut s = String::new();
1600 write!(s, "expected [").unwrap();
1601 let list = |s: &mut String, indices: &Vec<usize>| {
1602 let mut indices = indices.iter().cloned();
1603 if let Some(first) = indices.next() {
1604 write!(s, "`{}`", substs[first]).unwrap();
1606 write!(s, ", `{}`", substs[i]).unwrap();
1610 list(&mut s, prev_indices);
1611 write!(s, "], got [").unwrap();
1612 list(&mut s, &indices);
1613 write!(s, "]").unwrap();
1614 err.span_label(span, s);
1615 err.span_note(prev_span, "previous use here");
1619 self.found = Some((span, concrete_type, indices));
1623 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
1624 self.def_id, def_id,
1630 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1631 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1632 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1634 fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
1635 debug!("find_existential_constraints: visiting {:?}", it);
1636 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1637 // The opaque type itself or its children are not within its reveal scope.
1638 if def_id != self.def_id {
1640 intravisit::walk_item(self, it);
1643 fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
1644 debug!("find_existential_constraints: visiting {:?}", it);
1645 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1646 // The opaque type itself or its children are not within its reveal scope.
1647 if def_id != self.def_id {
1649 intravisit::walk_impl_item(self, it);
1652 fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
1653 debug!("find_existential_constraints: visiting {:?}", it);
1654 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1656 intravisit::walk_trait_item(self, it);
1660 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1661 let scope = tcx.hir().get_defining_scope(hir_id);
1662 let mut locator = ConstraintLocator { def_id, tcx, found: None };
1664 debug!("find_opaque_ty_constraints: scope={:?}", scope);
1666 if scope == hir::CRATE_HIR_ID {
1667 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1669 debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
1670 match tcx.hir().get(scope) {
1671 // We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
1672 // This allows our visitor to process the defining item itself, causing
1673 // it to pick up any 'sibling' defining uses.
1675 // For example, this code:
1678 // type Blah = impl Debug;
1679 // let my_closure = || -> Blah { true };
1683 // requires us to explicitly process `foo()` in order
1684 // to notice the defining usage of `Blah`.
1685 Node::Item(ref it) => locator.visit_item(it),
1686 Node::ImplItem(ref it) => locator.visit_impl_item(it),
1687 Node::TraitItem(ref it) => locator.visit_trait_item(it),
1688 other => bug!("{:?} is not a valid scope for an opaque type item", other),
1692 match locator.found {
1693 Some((_, ty, _)) => ty,
1695 let span = tcx.def_span(def_id);
1696 tcx.sess.span_err(span, "could not find defining uses");
1702 pub fn get_infer_ret_ty(output: &'hir hir::FunctionRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1703 if let hir::FunctionRetTy::Return(ref ty) = output {
1704 if let hir::TyKind::Infer = ty.kind {
1711 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1712 use rustc::hir::Node::*;
1715 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1717 let icx = ItemCtxt::new(tcx, def_id);
1719 match tcx.hir().get(hir_id) {
1720 TraitItem(hir::TraitItem {
1721 kind: TraitItemKind::Method(sig, TraitMethod::Provided(_)),
1724 | ImplItem(hir::ImplItem { kind: ImplItemKind::Method(sig, _), .. })
1725 | Item(hir::Item { kind: ItemKind::Fn(sig, _, _), .. }) => {
1726 match get_infer_ret_ty(&sig.decl.output) {
1728 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1729 let mut diag = bad_placeholder_type(tcx, ty.span);
1730 let ret_ty = fn_sig.output();
1731 if ret_ty != tcx.types.err {
1732 diag.span_suggestion(
1734 "replace `_` with the correct return type",
1736 Applicability::MaybeIncorrect,
1740 ty::Binder::bind(fn_sig)
1742 None => AstConv::ty_of_fn(&icx, sig.header.unsafety, sig.header.abi, &sig.decl),
1746 TraitItem(hir::TraitItem {
1747 kind: TraitItemKind::Method(FnSig { header, decl }, _),
1749 }) => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl),
1751 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(ref fn_decl, _, _), .. }) => {
1752 let abi = tcx.hir().get_foreign_abi(hir_id);
1753 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1756 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1757 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1759 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1760 ty::Binder::bind(tcx.mk_fn_sig(
1764 hir::Unsafety::Normal,
1769 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1770 // Closure signatures are not like other function
1771 // signatures and cannot be accessed through `fn_sig`. For
1772 // example, a closure signature excludes the `self`
1773 // argument. In any case they are embedded within the
1774 // closure type as part of the `ClosureSubsts`.
1777 // the signature of a closure, you should use the
1778 // `closure_sig` method on the `ClosureSubsts`:
1780 // closure_substs.sig(def_id, tcx)
1782 // or, inside of an inference context, you can use
1784 // infcx.closure_sig(def_id, closure_substs)
1785 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1789 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1794 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1795 let icx = ItemCtxt::new(tcx, def_id);
1797 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1798 match tcx.hir().expect_item(hir_id).kind {
1799 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1800 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1801 let selfty = tcx.type_of(def_id);
1802 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1809 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1810 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1811 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1812 let item = tcx.hir().expect_item(hir_id);
1814 hir::ItemKind::Impl(_, hir::ImplPolarity::Negative, ..) => {
1815 if is_rustc_reservation {
1816 tcx.sess.span_err(item.span, "reservation impls can't be negative");
1818 ty::ImplPolarity::Negative
1820 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, None, _, _) => {
1821 if is_rustc_reservation {
1822 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1824 ty::ImplPolarity::Positive
1826 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, Some(_tr), _, _) => {
1827 if is_rustc_reservation {
1828 ty::ImplPolarity::Reservation
1830 ty::ImplPolarity::Positive
1833 ref item => bug!("impl_polarity: {:?} not an impl", item),
1837 /// Returns the early-bound lifetimes declared in this generics
1838 /// listing. For anything other than fns/methods, this is just all
1839 /// the lifetimes that are declared. For fns or methods, we have to
1840 /// screen out those that do not appear in any where-clauses etc using
1841 /// `resolve_lifetime::early_bound_lifetimes`.
1842 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1844 generics: &'a hir::Generics<'a>,
1845 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1846 generics.params.iter().filter(move |param| match param.kind {
1847 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1852 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1853 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1854 /// inferred constraints concerning which regions outlive other regions.
1855 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1856 debug!("predicates_defined_on({:?})", def_id);
1857 let mut result = tcx.explicit_predicates_of(def_id);
1858 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1859 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1860 if !inferred_outlives.is_empty() {
1862 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1863 def_id, inferred_outlives,
1865 if result.predicates.is_empty() {
1866 result.predicates = inferred_outlives;
1868 result.predicates = tcx
1870 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1873 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1877 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1878 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1879 /// `Self: Trait` predicates for traits.
1880 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1881 let mut result = tcx.predicates_defined_on(def_id);
1883 if tcx.is_trait(def_id) {
1884 // For traits, add `Self: Trait` predicate. This is
1885 // not part of the predicates that a user writes, but it
1886 // is something that one must prove in order to invoke a
1887 // method or project an associated type.
1889 // In the chalk setup, this predicate is not part of the
1890 // "predicates" for a trait item. But it is useful in
1891 // rustc because if you directly (e.g.) invoke a trait
1892 // method like `Trait::method(...)`, you must naturally
1893 // prove that the trait applies to the types that were
1894 // used, and adding the predicate into this list ensures
1895 // that this is done.
1896 let span = tcx.def_span(def_id);
1898 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
1899 ty::TraitRef::identity(tcx, def_id).to_predicate(),
1903 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1907 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1908 /// N.B., this does not include any implied/inferred constraints.
1909 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1911 use rustc_data_structures::fx::FxHashSet;
1913 debug!("explicit_predicates_of(def_id={:?})", def_id);
1915 /// A data structure with unique elements, which preserves order of insertion.
1916 /// Preserving the order of insertion is important here so as not to break
1917 /// compile-fail UI tests.
1918 // FIXME(eddyb) just use `IndexSet` from `indexmap`.
1919 struct UniquePredicates<'tcx> {
1920 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1921 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1924 impl<'tcx> UniquePredicates<'tcx> {
1926 UniquePredicates { predicates: vec![], uniques: FxHashSet::default() }
1929 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
1930 if self.uniques.insert(value) {
1931 self.predicates.push(value);
1935 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
1942 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1943 let node = tcx.hir().get(hir_id);
1945 let mut is_trait = None;
1946 let mut is_default_impl_trait = None;
1948 let icx = ItemCtxt::new(tcx, def_id);
1950 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
1952 let mut predicates = UniquePredicates::new();
1954 let ast_generics = match node {
1955 Node::TraitItem(item) => &item.generics,
1957 Node::ImplItem(item) => match item.kind {
1958 ImplItemKind::OpaqueTy(ref bounds) => {
1959 ty::print::with_no_queries(|| {
1960 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1961 let opaque_ty = tcx.mk_opaque(def_id, substs);
1963 "explicit_predicates_of({:?}): created opaque type {:?}",
1967 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
1968 let bounds = AstConv::compute_bounds(
1972 SizedByDefault::Yes,
1973 tcx.def_span(def_id),
1976 predicates.extend(bounds.predicates(tcx, opaque_ty));
1980 _ => &item.generics,
1983 Node::Item(item) => {
1985 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
1986 if defaultness.is_default() {
1987 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1991 ItemKind::Fn(.., ref generics, _)
1992 | ItemKind::TyAlias(_, ref generics)
1993 | ItemKind::Enum(_, ref generics)
1994 | ItemKind::Struct(_, ref generics)
1995 | ItemKind::Union(_, ref generics) => generics,
1997 ItemKind::Trait(_, _, ref generics, .., items) => {
1998 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
2001 ItemKind::TraitAlias(ref generics, _) => {
2002 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &[]));
2005 ItemKind::OpaqueTy(OpaqueTy {
2011 let bounds_predicates = ty::print::with_no_queries(|| {
2012 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2013 let opaque_ty = tcx.mk_opaque(def_id, substs);
2015 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2016 let bounds = AstConv::compute_bounds(
2020 SizedByDefault::Yes,
2021 tcx.def_span(def_id),
2024 bounds.predicates(tcx, opaque_ty)
2026 if impl_trait_fn.is_some() {
2028 return ty::GenericPredicates {
2030 predicates: tcx.arena.alloc_from_iter(bounds_predicates),
2033 // named opaque types
2034 predicates.extend(bounds_predicates);
2043 Node::ForeignItem(item) => match item.kind {
2044 ForeignItemKind::Static(..) => NO_GENERICS,
2045 ForeignItemKind::Fn(_, _, ref generics) => generics,
2046 ForeignItemKind::Type => NO_GENERICS,
2052 let generics = tcx.generics_of(def_id);
2053 let parent_count = generics.parent_count as u32;
2054 let has_own_self = generics.has_self && parent_count == 0;
2056 // Below we'll consider the bounds on the type parameters (including `Self`)
2057 // and the explicit where-clauses, but to get the full set of predicates
2058 // on a trait we need to add in the supertrait bounds and bounds found on
2059 // associated types.
2060 if let Some((_trait_ref, _)) = is_trait {
2061 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2064 // In default impls, we can assume that the self type implements
2065 // the trait. So in:
2067 // default impl Foo for Bar { .. }
2069 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2070 // (see below). Recall that a default impl is not itself an impl, but rather a
2071 // set of defaults that can be incorporated into another impl.
2072 if let Some(trait_ref) = is_default_impl_trait {
2073 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2076 // Collect the region predicates that were declared inline as
2077 // well. In the case of parameters declared on a fn or method, we
2078 // have to be careful to only iterate over early-bound regions.
2079 let mut index = parent_count + has_own_self as u32;
2080 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2081 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2082 def_id: tcx.hir().local_def_id(param.hir_id),
2084 name: param.name.ident().name,
2089 GenericParamKind::Lifetime { .. } => {
2090 param.bounds.iter().for_each(|bound| match bound {
2091 hir::GenericBound::Outlives(lt) => {
2092 let bound = AstConv::ast_region_to_region(&icx, <, None);
2093 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2094 predicates.push((outlives.to_predicate(), lt.span));
2103 // Collect the predicates that were written inline by the user on each
2104 // type parameter (e.g., `<T: Foo>`).
2105 for param in &ast_generics.params {
2106 if let GenericParamKind::Type { .. } = param.kind {
2107 let name = param.name.ident().name;
2108 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2111 let sized = SizedByDefault::Yes;
2112 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2113 predicates.extend(bounds.predicates(tcx, param_ty));
2117 // Add in the bounds that appear in the where-clause.
2118 let where_clause = &ast_generics.where_clause;
2119 for predicate in where_clause.predicates {
2121 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2122 let ty = icx.to_ty(&bound_pred.bounded_ty);
2124 // Keep the type around in a dummy predicate, in case of no bounds.
2125 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2126 // is still checked for WF.
2127 if bound_pred.bounds.is_empty() {
2128 if let ty::Param(_) = ty.kind {
2129 // This is a `where T:`, which can be in the HIR from the
2130 // transformation that moves `?Sized` to `T`'s declaration.
2131 // We can skip the predicate because type parameters are
2132 // trivially WF, but also we *should*, to avoid exposing
2133 // users who never wrote `where Type:,` themselves, to
2134 // compiler/tooling bugs from not handling WF predicates.
2136 let span = bound_pred.bounded_ty.span;
2137 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2139 ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)),
2145 for bound in bound_pred.bounds.iter() {
2147 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2148 let mut bounds = Bounds::default();
2149 let _ = AstConv::instantiate_poly_trait_ref(
2155 predicates.extend(bounds.predicates(tcx, ty));
2158 &hir::GenericBound::Outlives(ref lifetime) => {
2159 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2160 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2161 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2167 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2168 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2169 predicates.extend(region_pred.bounds.iter().map(|bound| {
2170 let (r2, span) = match bound {
2171 hir::GenericBound::Outlives(lt) => {
2172 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2176 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2178 (ty::Predicate::RegionOutlives(pred), span)
2182 &hir::WherePredicate::EqPredicate(..) => {
2188 // Add predicates from associated type bounds.
2189 if let Some((self_trait_ref, trait_items)) = is_trait {
2190 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2191 associated_item_predicates(tcx, def_id, self_trait_ref, trait_item_ref)
2195 let mut predicates = predicates.predicates;
2197 // Subtle: before we store the predicates into the tcx, we
2198 // sort them so that predicates like `T: Foo<Item=U>` come
2199 // before uses of `U`. This avoids false ambiguity errors
2200 // in trait checking. See `setup_constraining_predicates`
2202 if let Node::Item(&Item { kind: ItemKind::Impl(..), .. }) = node {
2203 let self_ty = tcx.type_of(def_id);
2204 let trait_ref = tcx.impl_trait_ref(def_id);
2205 cgp::setup_constraining_predicates(
2209 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2213 let result = ty::GenericPredicates {
2214 parent: generics.parent,
2215 predicates: tcx.arena.alloc_from_iter(predicates),
2217 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2221 fn associated_item_predicates(
2224 self_trait_ref: ty::TraitRef<'tcx>,
2225 trait_item_ref: &hir::TraitItemRef,
2226 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2227 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2228 let item_def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
2229 let bounds = match trait_item.kind {
2230 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2231 _ => return Vec::new(),
2234 let is_gat = !tcx.generics_of(item_def_id).params.is_empty();
2236 let mut had_error = false;
2238 let mut unimplemented_error = |arg_kind: &str| {
2243 &format!("{}-generic associated types are not yet implemented", arg_kind),
2245 .note("for more information, see https://github.com/rust-lang/rust/issues/44265")
2251 let mk_bound_param = |param: &ty::GenericParamDef, _: &_| {
2253 ty::GenericParamDefKind::Lifetime => tcx
2254 .mk_region(ty::RegionKind::ReLateBound(
2256 ty::BoundRegion::BrNamed(param.def_id, param.name),
2259 // FIXME(generic_associated_types): Use bound types and constants
2260 // once they are handled by the trait system.
2261 ty::GenericParamDefKind::Type { .. } => {
2262 unimplemented_error("type");
2263 tcx.types.err.into()
2265 ty::GenericParamDefKind::Const => {
2266 unimplemented_error("const");
2267 tcx.consts.err.into()
2272 let bound_substs = if is_gat {
2275 // trait X<'a, B, const C: usize> {
2276 // type T<'d, E, const F: usize>: Default;
2279 // We need to create predicates on the trait:
2281 // for<'d, E, const F: usize>
2282 // <Self as X<'a, B, const C: usize>>::T<'d, E, const F: usize>: Sized + Default
2284 // We substitute escaping bound parameters for the generic
2285 // arguments to the associated type which are then bound by
2286 // the `Binder` around the the predicate.
2288 // FIXME(generic_associated_types): Currently only lifetimes are handled.
2289 self_trait_ref.substs.extend_to(tcx, item_def_id, mk_bound_param)
2291 self_trait_ref.substs
2294 let assoc_ty = tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id), bound_substs);
2296 let bounds = AstConv::compute_bounds(
2297 &ItemCtxt::new(tcx, def_id),
2300 SizedByDefault::Yes,
2304 let predicates = bounds.predicates(tcx, assoc_ty);
2307 // We use shifts to get the regions that we're substituting to
2308 // be bound by the binders in the `Predicate`s rather that
2310 let shifted_in = ty::fold::shift_vars(tcx, &predicates, 1);
2311 let substituted = shifted_in.subst(tcx, bound_substs);
2312 ty::fold::shift_out_vars(tcx, &substituted, 1)
2318 /// Converts a specific `GenericBound` from the AST into a set of
2319 /// predicates that apply to the self type. A vector is returned
2320 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2321 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2322 /// and `<T as Bar>::X == i32`).
2323 fn predicates_from_bound<'tcx>(
2324 astconv: &dyn AstConv<'tcx>,
2326 bound: &'tcx hir::GenericBound<'tcx>,
2327 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2329 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2330 let mut bounds = Bounds::default();
2331 let _ = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut bounds);
2332 bounds.predicates(astconv.tcx(), param_ty)
2334 hir::GenericBound::Outlives(ref lifetime) => {
2335 let region = astconv.ast_region_to_region(lifetime, None);
2336 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2337 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2339 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2343 fn compute_sig_of_foreign_fn_decl<'tcx>(
2346 decl: &'tcx hir::FnDecl<'tcx>,
2348 ) -> ty::PolyFnSig<'tcx> {
2349 let unsafety = if abi == abi::Abi::RustIntrinsic {
2350 intrinsic_operation_unsafety(&tcx.item_name(def_id).as_str())
2352 hir::Unsafety::Unsafe
2354 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2356 // Feature gate SIMD types in FFI, since I am not sure that the
2357 // ABIs are handled at all correctly. -huonw
2358 if abi != abi::Abi::RustIntrinsic
2359 && abi != abi::Abi::PlatformIntrinsic
2360 && !tcx.features().simd_ffi
2362 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2368 "use of SIMD type `{}` in FFI is highly experimental and \
2369 may result in invalid code",
2370 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2373 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2377 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2380 if let hir::Return(ref ty) = decl.output {
2381 check(&ty, *fty.output().skip_binder())
2388 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2389 match tcx.hir().get_if_local(def_id) {
2390 Some(Node::ForeignItem(..)) => true,
2392 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2396 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2397 match tcx.hir().get_if_local(def_id) {
2398 Some(Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. }))
2399 | Some(Node::ForeignItem(&hir::ForeignItem {
2400 kind: hir::ForeignItemKind::Static(_, mutbl),
2404 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2408 fn from_target_feature(
2411 attr: &ast::Attribute,
2412 whitelist: &FxHashMap<String, Option<Symbol>>,
2413 target_features: &mut Vec<Symbol>,
2415 let list = match attr.meta_item_list() {
2419 let bad_item = |span| {
2420 let msg = "malformed `target_feature` attribute input";
2421 let code = "enable = \"..\"".to_owned();
2423 .struct_span_err(span, &msg)
2424 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2427 let rust_features = tcx.features();
2429 // Only `enable = ...` is accepted in the meta-item list.
2430 if !item.check_name(sym::enable) {
2431 bad_item(item.span());
2435 // Must be of the form `enable = "..."` (a string).
2436 let value = match item.value_str() {
2437 Some(value) => value,
2439 bad_item(item.span());
2444 // We allow comma separation to enable multiple features.
2445 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2446 // Only allow whitelisted features per platform.
2447 let feature_gate = match whitelist.get(feature) {
2451 format!("the feature named `{}` is not valid for this target", feature);
2452 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2455 format!("`{}` is not valid for this target", feature),
2457 if feature.starts_with("+") {
2458 let valid = whitelist.contains_key(&feature[1..]);
2460 err.help("consider removing the leading `+` in the feature name");
2468 // Only allow features whose feature gates have been enabled.
2469 let allowed = match feature_gate.as_ref().map(|s| *s) {
2470 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2471 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2472 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2473 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2474 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2475 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2476 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2477 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2478 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2479 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2480 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2481 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2482 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2483 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2484 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2485 Some(name) => bug!("unknown target feature gate {}", name),
2488 if !allowed && id.is_local() {
2489 feature_gate::feature_err(
2490 &tcx.sess.parse_sess,
2491 feature_gate.unwrap(),
2493 &format!("the target feature `{}` is currently unstable", feature),
2497 Some(Symbol::intern(feature))
2502 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2503 use rustc::mir::mono::Linkage::*;
2505 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2506 // applicable to variable declarations and may not really make sense for
2507 // Rust code in the first place but whitelist them anyway and trust that
2508 // the user knows what s/he's doing. Who knows, unanticipated use cases
2509 // may pop up in the future.
2511 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2512 // and don't have to be, LLVM treats them as no-ops.
2514 "appending" => Appending,
2515 "available_externally" => AvailableExternally,
2517 "extern_weak" => ExternalWeak,
2518 "external" => External,
2519 "internal" => Internal,
2520 "linkonce" => LinkOnceAny,
2521 "linkonce_odr" => LinkOnceODR,
2522 "private" => Private,
2524 "weak_odr" => WeakODR,
2526 let span = tcx.hir().span_if_local(def_id);
2527 if let Some(span) = span {
2528 tcx.sess.span_fatal(span, "invalid linkage specified")
2530 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2536 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2537 let attrs = tcx.get_attrs(id);
2539 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2541 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2543 let mut inline_span = None;
2544 let mut link_ordinal_span = None;
2545 for attr in attrs.iter() {
2546 if attr.check_name(sym::cold) {
2547 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2548 } else if attr.check_name(sym::rustc_allocator) {
2549 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2550 } else if attr.check_name(sym::unwind) {
2551 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2552 } else if attr.check_name(sym::ffi_returns_twice) {
2553 if tcx.is_foreign_item(id) {
2554 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2556 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2561 "`#[ffi_returns_twice]` may only be used on foreign functions"
2565 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2566 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2567 } else if attr.check_name(sym::naked) {
2568 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2569 } else if attr.check_name(sym::no_mangle) {
2570 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2571 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2572 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2573 } else if attr.check_name(sym::no_debug) {
2574 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2575 } else if attr.check_name(sym::used) {
2576 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2577 } else if attr.check_name(sym::thread_local) {
2578 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2579 } else if attr.check_name(sym::track_caller) {
2580 if tcx.fn_sig(id).abi() != abi::Abi::Rust {
2581 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2584 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2585 } else if attr.check_name(sym::export_name) {
2586 if let Some(s) = attr.value_str() {
2587 if s.as_str().contains("\0") {
2588 // `#[export_name = ...]` will be converted to a null-terminated string,
2589 // so it may not contain any null characters.
2594 "`export_name` may not contain null characters"
2598 codegen_fn_attrs.export_name = Some(s);
2600 } else if attr.check_name(sym::target_feature) {
2601 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2602 let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
2604 .struct_span_err(attr.span, msg)
2605 .span_label(attr.span, "can only be applied to `unsafe` functions")
2606 .span_label(tcx.def_span(id), "not an `unsafe` function")
2609 from_target_feature(tcx, id, attr, &whitelist, &mut codegen_fn_attrs.target_features);
2610 } else if attr.check_name(sym::linkage) {
2611 if let Some(val) = attr.value_str() {
2612 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2614 } else if attr.check_name(sym::link_section) {
2615 if let Some(val) = attr.value_str() {
2616 if val.as_str().bytes().any(|b| b == 0) {
2618 "illegal null byte in link_section \
2622 tcx.sess.span_err(attr.span, &msg);
2624 codegen_fn_attrs.link_section = Some(val);
2627 } else if attr.check_name(sym::link_name) {
2628 codegen_fn_attrs.link_name = attr.value_str();
2629 } else if attr.check_name(sym::link_ordinal) {
2630 link_ordinal_span = Some(attr.span);
2631 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2632 codegen_fn_attrs.link_ordinal = ordinal;
2637 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2638 if !attr.has_name(sym::inline) {
2641 match attr.meta().map(|i| i.kind) {
2642 Some(MetaItemKind::Word) => {
2646 Some(MetaItemKind::List(ref items)) => {
2648 inline_span = Some(attr.span);
2649 if items.len() != 1 {
2650 span_err!(tcx.sess.diagnostic(), attr.span, E0534, "expected one argument");
2652 } else if list_contains_name(&items[..], sym::always) {
2654 } else if list_contains_name(&items[..], sym::never) {
2657 span_err!(tcx.sess.diagnostic(), items[0].span(), E0535, "invalid argument");
2662 Some(MetaItemKind::NameValue(_)) => ia,
2667 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2668 if !attr.has_name(sym::optimize) {
2671 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2672 match attr.meta().map(|i| i.kind) {
2673 Some(MetaItemKind::Word) => {
2674 err(attr.span, "expected one argument");
2677 Some(MetaItemKind::List(ref items)) => {
2679 inline_span = Some(attr.span);
2680 if items.len() != 1 {
2681 err(attr.span, "expected one argument");
2683 } else if list_contains_name(&items[..], sym::size) {
2685 } else if list_contains_name(&items[..], sym::speed) {
2688 err(items[0].span(), "invalid argument");
2692 Some(MetaItemKind::NameValue(_)) => ia,
2697 // If a function uses #[target_feature] it can't be inlined into general
2698 // purpose functions as they wouldn't have the right target features
2699 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2702 if codegen_fn_attrs.target_features.len() > 0 {
2703 if codegen_fn_attrs.inline == InlineAttr::Always {
2704 if let Some(span) = inline_span {
2707 "cannot use `#[inline(always)]` with \
2708 `#[target_feature]`",
2714 // Weak lang items have the same semantics as "std internal" symbols in the
2715 // sense that they're preserved through all our LTO passes and only
2716 // strippable by the linker.
2718 // Additionally weak lang items have predetermined symbol names.
2719 if tcx.is_weak_lang_item(id) {
2720 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2722 if let Some(name) = weak_lang_items::link_name(&attrs) {
2723 codegen_fn_attrs.export_name = Some(name);
2724 codegen_fn_attrs.link_name = Some(name);
2726 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2728 // Internal symbols to the standard library all have no_mangle semantics in
2729 // that they have defined symbol names present in the function name. This
2730 // also applies to weak symbols where they all have known symbol names.
2731 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2732 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2738 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
2739 use syntax::ast::{Lit, LitIntType, LitKind};
2740 let meta_item_list = attr.meta_item_list();
2741 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
2742 let sole_meta_list = match meta_item_list {
2743 Some([item]) => item.literal(),
2746 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
2747 if *ordinal <= std::usize::MAX as u128 {
2748 Some(*ordinal as usize)
2750 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
2752 .struct_span_err(attr.span, &msg)
2753 .note("the value may not exceed `std::usize::MAX`")
2759 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
2760 .note("an unsuffixed integer value, e.g., `1`, is expected")
2766 fn check_link_name_xor_ordinal(
2768 codegen_fn_attrs: &CodegenFnAttrs,
2769 inline_span: Option<Span>,
2771 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
2774 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
2775 if let Some(span) = inline_span {
2776 tcx.sess.span_err(span, msg);