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::constrained_generic_params as cgp;
19 use crate::check::intrinsic::intrinsic_operation_unsafety;
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::{Subst, InternalSubsts};
26 use rustc::ty::util::Discr;
27 use rustc::ty::util::IntTypeExt;
28 use rustc::ty::subst::GenericArgKind;
29 use rustc::ty::{self, AdtKind, DefIdTree, ToPolyTraitRef, Ty, TyCtxt, Const};
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::{InlineAttr, OptimizeAttr, list_contains_name, mark_used};
38 use syntax::feature_gate;
39 use syntax::symbol::{kw, Symbol, sym};
40 use syntax_pos::{Span, DUMMY_SP};
42 use rustc::hir::def::{CtorKind, Res, DefKind};
44 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
45 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
46 use rustc::hir::GenericParamKind;
47 use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
49 use errors::{Applicability, DiagnosticId, StashKey};
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 ///////////////////////////////////////////////////////////////////////////
103 struct CollectItemTypesVisitor<'tcx> {
107 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
108 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
109 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
112 fn visit_item(&mut self, item: &'tcx hir::Item) {
113 convert_item(self.tcx, item.hir_id);
114 intravisit::walk_item(self, item);
117 fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
118 for param in &generics.params {
120 hir::GenericParamKind::Lifetime { .. } => {}
121 hir::GenericParamKind::Type {
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) {
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) {
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) {
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 = tcx.sess.struct_span_err_with_code(
163 "the type placeholder `_` is not allowed within types on item signatures",
164 DiagnosticId::Error("E0121".into()),
166 diag.span_label(span, "not allowed in type signatures");
170 impl ItemCtxt<'tcx> {
171 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
172 ItemCtxt { tcx, item_def_id }
175 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty) -> Ty<'tcx> {
176 AstConv::ast_ty_to_ty(self, ast_ty)
180 impl AstConv<'tcx> for ItemCtxt<'tcx> {
181 fn tcx(&self) -> TyCtxt<'tcx> {
185 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
188 .type_param_predicates((self.item_def_id, def_id))
193 _: Option<&ty::GenericParamDef>,
195 ) -> Option<ty::Region<'tcx>> {
199 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
200 bad_placeholder_type(self.tcx(), span).emit();
208 _: Option<&ty::GenericParamDef>,
210 ) -> &'tcx Const<'tcx> {
211 bad_placeholder_type(self.tcx(), span).emit();
213 self.tcx().consts.err
216 fn projected_ty_from_poly_trait_ref(
220 poly_trait_ref: ty::PolyTraitRef<'tcx>,
222 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
223 self.tcx().mk_projection(item_def_id, trait_ref.substs)
225 // There are no late-bound regions; we can just ignore the binder.
230 "cannot extract an associated type from a higher-ranked trait bound \
237 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
238 // Types in item signatures are not normalized to avoid undue dependencies.
242 fn set_tainted_by_errors(&self) {
243 // There's no obvious place to track this, so just let it go.
246 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
247 // There's no place to record types from signatures?
251 /// Returns the predicates defined on `item_def_id` of the form
252 /// `X: Foo` where `X` is the type parameter `def_id`.
253 fn type_param_predicates(
255 (item_def_id, def_id): (DefId, DefId),
256 ) -> ty::GenericPredicates<'_> {
259 // In the AST, bounds can derive from two places. Either
260 // written inline like `<T: Foo>` or in a where-clause like
263 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
264 let param_owner = tcx.hir().ty_param_owner(param_id);
265 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
266 let generics = tcx.generics_of(param_owner_def_id);
267 let index = generics.param_def_id_to_index[&def_id];
268 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
270 // Don't look for bounds where the type parameter isn't in scope.
271 let parent = if item_def_id == param_owner_def_id {
274 tcx.generics_of(item_def_id).parent
277 let mut result = parent.map(|parent| {
278 let icx = ItemCtxt::new(tcx, parent);
279 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
280 }).unwrap_or_default();
281 let mut extend = None;
283 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
284 let ast_generics = match tcx.hir().get(item_hir_id) {
285 Node::TraitItem(item) => &item.generics,
287 Node::ImplItem(item) => &item.generics,
289 Node::Item(item) => {
291 ItemKind::Fn(.., ref generics, _)
292 | ItemKind::Impl(_, _, _, ref generics, ..)
293 | ItemKind::TyAlias(_, ref generics)
294 | ItemKind::OpaqueTy(OpaqueTy {
299 | ItemKind::Enum(_, ref generics)
300 | ItemKind::Struct(_, ref generics)
301 | ItemKind::Union(_, ref generics) => generics,
302 ItemKind::Trait(_, _, ref generics, ..) => {
303 // Implied `Self: Trait` and supertrait bounds.
304 if param_id == item_hir_id {
305 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
306 extend = Some((identity_trait_ref.to_predicate(), item.span));
314 Node::ForeignItem(item) => match item.kind {
315 ForeignItemKind::Fn(_, _, ref generics) => generics,
322 let icx = ItemCtxt::new(tcx, item_def_id);
323 let extra_predicates = extend.into_iter().chain(
324 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
326 .filter(|(predicate, _)| {
328 ty::Predicate::Trait(ref data) => data.skip_binder().self_ty().is_param(index),
333 result.predicates = tcx.arena.alloc_from_iter(
334 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,
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 {
465 impl_trait_fn: Some(_),
469 hir::ItemKind::OpaqueTy(..)
470 | hir::ItemKind::TyAlias(..)
471 | hir::ItemKind::Static(..)
472 | hir::ItemKind::Const(..)
473 | hir::ItemKind::Fn(..) => {
474 tcx.generics_of(def_id);
476 tcx.predicates_of(def_id);
477 if let hir::ItemKind::Fn(..) = it.kind {
484 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
485 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
486 let def_id = tcx.hir().local_def_id(trait_item.hir_id);
487 tcx.generics_of(def_id);
489 match trait_item.kind {
490 hir::TraitItemKind::Const(..)
491 | hir::TraitItemKind::Type(_, Some(_))
492 | hir::TraitItemKind::Method(..) => {
494 if let hir::TraitItemKind::Method(..) = trait_item.kind {
499 hir::TraitItemKind::Type(_, None) => {}
502 tcx.predicates_of(def_id);
505 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
506 let def_id = tcx.hir().local_def_id(impl_item_id);
507 tcx.generics_of(def_id);
509 tcx.predicates_of(def_id);
510 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).kind {
515 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
516 let def_id = tcx.hir().local_def_id(ctor_id);
517 tcx.generics_of(def_id);
519 tcx.predicates_of(def_id);
522 fn convert_enum_variant_types(
525 variants: &[hir::Variant]
527 let def = tcx.adt_def(def_id);
528 let repr_type = def.repr.discr_type();
529 let initial = repr_type.initial_discriminant(tcx);
530 let mut prev_discr = None::<Discr<'_>>;
532 // fill the discriminant values and field types
533 for variant in variants {
534 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
536 if let Some(ref e) = variant.disr_expr {
537 let expr_did = tcx.hir().local_def_id(e.hir_id);
538 def.eval_explicit_discr(tcx, expr_did)
539 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
546 "enum discriminant overflowed"
549 format!("overflowed on value after {}", prev_discr.unwrap()),
551 "explicitly set `{} = {}` if that is desired outcome",
552 variant.ident, wrapped_discr
556 }.unwrap_or(wrapped_discr),
559 for f in variant.data.fields() {
560 let def_id = tcx.hir().local_def_id(f.hir_id);
561 tcx.generics_of(def_id);
563 tcx.predicates_of(def_id);
566 // Convert the ctor, if any. This also registers the variant as
568 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
569 convert_variant_ctor(tcx, ctor_hir_id);
576 variant_did: Option<DefId>,
577 ctor_did: Option<DefId>,
579 discr: ty::VariantDiscr,
580 def: &hir::VariantData,
581 adt_kind: ty::AdtKind,
583 ) -> ty::VariantDef {
584 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
585 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
590 let fid = tcx.hir().local_def_id(f.hir_id);
591 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
592 if let Some(prev_span) = dup_span {
597 "field `{}` is already declared",
599 ).span_label(f.span, "field already declared")
600 .span_label(prev_span, format!("`{}` first declared here", f.ident))
603 seen_fields.insert(f.ident.modern(), f.span);
609 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
613 let recovered = match def {
614 hir::VariantData::Struct(_, r) => *r,
624 CtorKind::from_hir(def),
631 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
634 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
635 let item = match tcx.hir().get(hir_id) {
636 Node::Item(item) => item,
640 let repr = ReprOptions::new(tcx, def_id);
641 let (kind, variants) = match item.kind {
642 ItemKind::Enum(ref def, _) => {
643 let mut distance_from_explicit = 0;
644 let variants = def.variants
647 let variant_did = Some(tcx.hir().local_def_id(v.id));
648 let ctor_did = v.data.ctor_hir_id()
649 .map(|hir_id| tcx.hir().local_def_id(hir_id));
651 let discr = if let Some(ref e) = v.disr_expr {
652 distance_from_explicit = 0;
653 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id))
655 ty::VariantDiscr::Relative(distance_from_explicit)
657 distance_from_explicit += 1;
659 convert_variant(tcx, variant_did, ctor_did, v.ident, discr,
660 &v.data, AdtKind::Enum, def_id)
664 (AdtKind::Enum, variants)
666 ItemKind::Struct(ref def, _) => {
667 let variant_did = None;
668 let ctor_did = def.ctor_hir_id()
669 .map(|hir_id| tcx.hir().local_def_id(hir_id));
671 let variants = std::iter::once(convert_variant(
672 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
673 AdtKind::Struct, def_id,
676 (AdtKind::Struct, variants)
678 ItemKind::Union(ref def, _) => {
679 let variant_did = None;
680 let ctor_did = def.ctor_hir_id()
681 .map(|hir_id| tcx.hir().local_def_id(hir_id));
683 let variants = std::iter::once(convert_variant(
684 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
685 AdtKind::Union, def_id,
688 (AdtKind::Union, variants)
692 tcx.alloc_adt_def(def_id, kind, variants, repr)
695 /// Ensures that the super-predicates of the trait with a `DefId`
696 /// of `trait_def_id` are converted and stored. This also ensures that
697 /// the transitive super-predicates are converted.
698 fn super_predicates_of(
701 ) -> ty::GenericPredicates<'_> {
702 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
703 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
705 let item = match tcx.hir().get(trait_hir_id) {
706 Node::Item(item) => item,
707 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
710 let (generics, bounds) = match item.kind {
711 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
712 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
713 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
716 let icx = ItemCtxt::new(tcx, trait_def_id);
718 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
719 let self_param_ty = tcx.types.self_param;
720 let superbounds1 = AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No,
723 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
725 // Convert any explicit superbounds in the where-clause,
726 // e.g., `trait Foo where Self: Bar`.
727 // In the case of trait aliases, however, we include all bounds in the where-clause,
728 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
729 // as one of its "superpredicates".
730 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
731 let superbounds2 = icx.type_parameter_bounds_in_generics(
732 generics, item.hir_id, self_param_ty, OnlySelfBounds(!is_trait_alias));
734 // Combine the two lists to form the complete set of superbounds:
735 let superbounds = &*tcx.arena.alloc_from_iter(
736 superbounds1.into_iter().chain(superbounds2)
739 // Now require that immediate supertraits are converted,
740 // which will, in turn, reach indirect supertraits.
741 for &(pred, span) in superbounds {
742 debug!("superbound: {:?}", pred);
743 if let ty::Predicate::Trait(bound) = pred {
744 tcx.at(span).super_predicates_of(bound.def_id());
748 ty::GenericPredicates {
750 predicates: superbounds,
754 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
755 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
756 let item = tcx.hir().expect_item(hir_id);
758 let (is_auto, unsafety) = match item.kind {
759 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
760 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
761 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
764 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
765 if paren_sugar && !tcx.features().unboxed_closures {
766 let mut err = tcx.sess.struct_span_err(
768 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
769 which traits can use parenthetical notation",
773 "add `#![feature(unboxed_closures)]` to \
774 the crate attributes to use it"
779 let is_marker = tcx.has_attr(def_id, sym::marker);
780 let def_path_hash = tcx.def_path_hash(def_id);
781 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
785 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
786 struct LateBoundRegionsDetector<'tcx> {
788 outer_index: ty::DebruijnIndex,
789 has_late_bound_regions: Option<Span>,
792 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
793 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
794 NestedVisitorMap::None
797 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
798 if self.has_late_bound_regions.is_some() {
802 hir::TyKind::BareFn(..) => {
803 self.outer_index.shift_in(1);
804 intravisit::walk_ty(self, ty);
805 self.outer_index.shift_out(1);
807 _ => intravisit::walk_ty(self, ty),
811 fn visit_poly_trait_ref(
813 tr: &'tcx hir::PolyTraitRef,
814 m: hir::TraitBoundModifier,
816 if self.has_late_bound_regions.is_some() {
819 self.outer_index.shift_in(1);
820 intravisit::walk_poly_trait_ref(self, tr, m);
821 self.outer_index.shift_out(1);
824 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
825 if self.has_late_bound_regions.is_some() {
829 match self.tcx.named_region(lt.hir_id) {
830 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
831 Some(rl::Region::LateBound(debruijn, _, _))
832 | Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
833 Some(rl::Region::LateBound(..))
834 | Some(rl::Region::LateBoundAnon(..))
835 | Some(rl::Region::Free(..))
837 self.has_late_bound_regions = Some(lt.span);
843 fn has_late_bound_regions<'tcx>(
845 generics: &'tcx hir::Generics,
846 decl: &'tcx hir::FnDecl,
848 let mut visitor = LateBoundRegionsDetector {
850 outer_index: ty::INNERMOST,
851 has_late_bound_regions: None,
853 for param in &generics.params {
854 if let GenericParamKind::Lifetime { .. } = param.kind {
855 if tcx.is_late_bound(param.hir_id) {
856 return Some(param.span);
860 visitor.visit_fn_decl(decl);
861 visitor.has_late_bound_regions
865 Node::TraitItem(item) => match item.kind {
866 hir::TraitItemKind::Method(ref sig, _) => {
867 has_late_bound_regions(tcx, &item.generics, &sig.decl)
871 Node::ImplItem(item) => match item.kind {
872 hir::ImplItemKind::Method(ref sig, _) => {
873 has_late_bound_regions(tcx, &item.generics, &sig.decl)
877 Node::ForeignItem(item) => match item.kind {
878 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
879 has_late_bound_regions(tcx, generics, fn_decl)
883 Node::Item(item) => match item.kind {
884 hir::ItemKind::Fn(ref fn_decl, .., ref generics, _) => {
885 has_late_bound_regions(tcx, generics, fn_decl)
893 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
896 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
898 let node = tcx.hir().get(hir_id);
899 let parent_def_id = match node {
900 Node::ImplItem(_) | Node::TraitItem(_) | Node::Variant(_) |
901 Node::Ctor(..) | Node::Field(_) => {
902 let parent_id = tcx.hir().get_parent_item(hir_id);
903 Some(tcx.hir().local_def_id(parent_id))
905 // FIXME(#43408) enable this in all cases when we get lazy normalization.
906 Node::AnonConst(&anon_const) => {
907 // HACK(eddyb) this provides the correct generics when the workaround
908 // for a const parameter `AnonConst` is being used elsewhere, as then
909 // there won't be the kind of cyclic dependency blocking #43408.
910 let expr = &tcx.hir().body(anon_const.body).value;
911 let icx = ItemCtxt::new(tcx, def_id);
912 if AstConv::const_param_def_id(&icx, expr).is_some() {
913 let parent_id = tcx.hir().get_parent_item(hir_id);
914 Some(tcx.hir().local_def_id(parent_id))
919 Node::Expr(&hir::Expr {
920 kind: hir::ExprKind::Closure(..),
922 }) => Some(tcx.closure_base_def_id(def_id)),
923 Node::Item(item) => match item.kind {
924 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => impl_trait_fn,
930 let mut opt_self = None;
931 let mut allow_defaults = false;
933 let no_generics = hir::Generics::empty();
934 let ast_generics = match node {
935 Node::TraitItem(item) => &item.generics,
937 Node::ImplItem(item) => &item.generics,
939 Node::Item(item) => {
941 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
945 ItemKind::TyAlias(_, ref generics)
946 | ItemKind::Enum(_, ref generics)
947 | ItemKind::Struct(_, ref generics)
948 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
949 | ItemKind::Union(_, ref generics) => {
950 allow_defaults = true;
954 ItemKind::Trait(_, _, ref generics, ..)
955 | ItemKind::TraitAlias(ref generics, ..) => {
956 // Add in the self type parameter.
958 // Something of a hack: use the node id for the trait, also as
959 // the node id for the Self type parameter.
960 let param_id = item.hir_id;
962 opt_self = Some(ty::GenericParamDef {
965 def_id: tcx.hir().local_def_id(param_id),
966 pure_wrt_drop: false,
967 kind: ty::GenericParamDefKind::Type {
969 object_lifetime_default: rl::Set1::Empty,
974 allow_defaults = true;
982 Node::ForeignItem(item) => match item.kind {
983 ForeignItemKind::Static(..) => &no_generics,
984 ForeignItemKind::Fn(_, _, ref generics) => generics,
985 ForeignItemKind::Type => &no_generics,
991 let has_self = opt_self.is_some();
992 let mut parent_has_self = false;
993 let mut own_start = has_self as u32;
994 let parent_count = parent_def_id.map_or(0, |def_id| {
995 let generics = tcx.generics_of(def_id);
996 assert_eq!(has_self, false);
997 parent_has_self = generics.has_self;
998 own_start = generics.count() as u32;
999 generics.parent_count + generics.params.len()
1002 let mut params: Vec<_> = opt_self.into_iter().collect();
1004 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1008 .map(|(i, param)| ty::GenericParamDef {
1009 name: param.name.ident().name,
1010 index: own_start + i as u32,
1011 def_id: tcx.hir().local_def_id(param.hir_id),
1012 pure_wrt_drop: param.pure_wrt_drop,
1013 kind: ty::GenericParamDefKind::Lifetime,
1017 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1019 // Now create the real type parameters.
1020 let type_start = own_start - has_self as u32 + params.len() as u32;
1026 .filter_map(|param| {
1027 let kind = match param.kind {
1028 GenericParamKind::Type {
1033 if !allow_defaults && default.is_some() {
1034 if !tcx.features().default_type_parameter_fallback {
1036 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1040 "defaults for type parameters are only allowed in \
1041 `struct`, `enum`, `type`, or `trait` definitions."
1047 ty::GenericParamDefKind::Type {
1048 has_default: default.is_some(),
1049 object_lifetime_default: object_lifetime_defaults
1051 .map_or(rl::Set1::Empty, |o| o[i]),
1055 GenericParamKind::Const { .. } => {
1056 ty::GenericParamDefKind::Const
1061 let param_def = ty::GenericParamDef {
1062 index: type_start + i as u32,
1063 name: param.name.ident().name,
1064 def_id: tcx.hir().local_def_id(param.hir_id),
1065 pure_wrt_drop: param.pure_wrt_drop,
1073 // provide junk type parameter defs - the only place that
1074 // cares about anything but the length is instantiation,
1075 // and we don't do that for closures.
1076 if let Node::Expr(&hir::Expr {
1077 kind: hir::ExprKind::Closure(.., gen),
1081 let dummy_args = if gen.is_some() {
1082 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1084 &["<closure_kind>", "<closure_signature>"][..]
1091 .map(|(i, &arg)| ty::GenericParamDef {
1092 index: type_start + i as u32,
1093 name: Symbol::intern(arg),
1095 pure_wrt_drop: false,
1096 kind: ty::GenericParamDefKind::Type {
1098 object_lifetime_default: rl::Set1::Empty,
1104 if let Some(upvars) = tcx.upvars(def_id) {
1105 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1106 ty::GenericParamDef {
1107 index: type_start + i,
1108 name: Symbol::intern("<upvar>"),
1110 pure_wrt_drop: false,
1111 kind: ty::GenericParamDefKind::Type {
1113 object_lifetime_default: rl::Set1::Empty,
1121 let param_def_id_to_index = params
1123 .map(|param| (param.def_id, param.index))
1126 tcx.arena.alloc(ty::Generics {
1127 parent: parent_def_id,
1130 param_def_id_to_index,
1131 has_self: has_self || parent_has_self,
1132 has_late_bound_regions: has_late_bound_regions(tcx, node),
1136 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
1141 "associated types are not yet supported in inherent impls (see #8995)"
1145 fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1146 checked_type_of(tcx, def_id, true).unwrap()
1149 fn infer_placeholder_type(
1152 body_id: hir::BodyId,
1156 let ty = tcx.typeck_tables_of(def_id).node_type(body_id.hir_id);
1158 // If this came from a free `const` or `static mut?` item,
1159 // then the user may have written e.g. `const A = 42;`.
1160 // In this case, the parser has stashed a diagnostic for
1161 // us to improve in typeck so we do that now.
1162 match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
1164 // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
1165 // We are typeck and have the real type, so remove that and suggest the actual type.
1166 err.suggestions.clear();
1167 err.span_suggestion(
1169 "provide a type for the item",
1170 format!("{}: {}", item_ident, ty),
1171 Applicability::MachineApplicable,
1176 let mut diag = bad_placeholder_type(tcx, span);
1177 if ty != tcx.types.err {
1178 diag.span_suggestion(
1180 "replace `_` with the correct type",
1182 Applicability::MaybeIncorrect,
1192 /// Same as [`type_of`] but returns [`Option`] instead of failing.
1194 /// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
1195 /// you'd better just call [`type_of`] directly.
1196 pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<'_>> {
1199 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1200 Some(hir_id) => hir_id,
1205 bug!("invalid node");
1209 let icx = ItemCtxt::new(tcx, def_id);
1211 Some(match tcx.hir().get(hir_id) {
1212 Node::TraitItem(item) => match item.kind {
1213 TraitItemKind::Method(..) => {
1214 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1215 tcx.mk_fn_def(def_id, substs)
1217 TraitItemKind::Const(ref ty, body_id) => {
1218 body_id.and_then(|body_id| {
1219 if let hir::TyKind::Infer = ty.kind {
1220 Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
1224 }).unwrap_or_else(|| icx.to_ty(ty))
1226 TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1227 TraitItemKind::Type(_, None) => {
1231 span_bug!(item.span, "associated type missing default");
1235 Node::ImplItem(item) => match item.kind {
1236 ImplItemKind::Method(..) => {
1237 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1238 tcx.mk_fn_def(def_id, substs)
1240 ImplItemKind::Const(ref ty, body_id) => {
1241 if let hir::TyKind::Infer = ty.kind {
1242 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1247 ImplItemKind::OpaqueTy(_) => {
1249 .impl_trait_ref(tcx.hir().get_parent_did(hir_id))
1252 report_assoc_ty_on_inherent_impl(tcx, item.span);
1255 find_opaque_ty_constraints(tcx, def_id)
1257 ImplItemKind::TyAlias(ref ty) => {
1259 .impl_trait_ref(tcx.hir().get_parent_did(hir_id))
1262 report_assoc_ty_on_inherent_impl(tcx, item.span);
1269 Node::Item(item) => {
1271 ItemKind::Static(ref ty, .., body_id)
1272 | ItemKind::Const(ref ty, body_id) => {
1273 if let hir::TyKind::Infer = ty.kind {
1274 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1279 ItemKind::TyAlias(ref ty, _)
1280 | ItemKind::Impl(.., ref ty, _) => icx.to_ty(ty),
1281 ItemKind::Fn(..) => {
1282 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1283 tcx.mk_fn_def(def_id, substs)
1285 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1286 let def = tcx.adt_def(def_id);
1287 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1288 tcx.mk_adt(def, substs)
1290 ItemKind::OpaqueTy(hir::OpaqueTy {
1291 impl_trait_fn: None,
1293 }) => find_opaque_ty_constraints(tcx, def_id),
1294 // Opaque types desugared from `impl Trait`.
1295 ItemKind::OpaqueTy(hir::OpaqueTy {
1296 impl_trait_fn: Some(owner),
1299 tcx.typeck_tables_of(owner)
1300 .concrete_opaque_types
1302 .map(|opaque| opaque.concrete_type)
1303 .unwrap_or_else(|| {
1304 // This can occur if some error in the
1305 // owner fn prevented us from populating
1306 // the `concrete_opaque_types` table.
1307 tcx.sess.delay_span_bug(
1310 "owner {:?} has no opaque type for {:?} in its tables",
1318 | ItemKind::TraitAlias(..)
1320 | ItemKind::ForeignMod(..)
1321 | ItemKind::GlobalAsm(..)
1322 | ItemKind::ExternCrate(..)
1323 | ItemKind::Use(..) => {
1329 "compute_type_of_item: unexpected item type: {:?}",
1336 Node::ForeignItem(foreign_item) => match foreign_item.kind {
1337 ForeignItemKind::Fn(..) => {
1338 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1339 tcx.mk_fn_def(def_id, substs)
1341 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1342 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1345 Node::Ctor(&ref def) | Node::Variant(
1346 hir::Variant { data: ref def, .. }
1348 VariantData::Unit(..) | VariantData::Struct(..) => {
1349 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1351 VariantData::Tuple(..) => {
1352 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1353 tcx.mk_fn_def(def_id, substs)
1357 Node::Field(field) => icx.to_ty(&field.ty),
1359 Node::Expr(&hir::Expr {
1360 kind: hir::ExprKind::Closure(.., gen),
1364 return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
1367 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1368 tcx.mk_closure(def_id, substs)
1371 Node::AnonConst(_) => {
1372 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1375 kind: hir::TyKind::Array(_, ref constant),
1378 | Node::Ty(&hir::Ty {
1379 kind: hir::TyKind::Typeof(ref constant),
1382 | Node::Expr(&hir::Expr {
1383 kind: ExprKind::Repeat(_, ref constant),
1385 }) if constant.hir_id == hir_id =>
1390 Node::Variant(Variant {
1391 disr_expr: Some(ref e),
1393 }) if e.hir_id == hir_id =>
1395 tcx.adt_def(tcx.hir().get_parent_did(hir_id))
1401 Node::Ty(&hir::Ty { kind: hir::TyKind::Path(_), .. }) |
1402 Node::Expr(&hir::Expr { kind: ExprKind::Struct(..), .. }) |
1403 Node::Expr(&hir::Expr { kind: ExprKind::Path(_), .. }) |
1404 Node::TraitRef(..) => {
1405 let path = match parent_node {
1407 kind: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1410 | Node::Expr(&hir::Expr {
1411 kind: ExprKind::Path(QPath::Resolved(_, ref path)),
1416 Node::Expr(&hir::Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
1417 if let QPath::Resolved(_, ref path) = **path {
1423 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
1427 if let Some(path) = path {
1428 let arg_index = path.segments.iter()
1429 .filter_map(|seg| seg.args.as_ref())
1430 .map(|generic_args| generic_args.args.as_ref())
1433 .filter(|arg| arg.is_const())
1435 .filter(|(_, arg)| arg.id() == hir_id)
1436 .map(|(index, _)| index)
1443 bug!("no arg matching AnonConst in path")
1447 // We've encountered an `AnonConst` in some path, so we need to
1448 // figure out which generic parameter it corresponds to and return
1449 // the relevant type.
1450 let generics = match path.res {
1451 Res::Def(DefKind::Ctor(..), def_id) => {
1452 tcx.generics_of(tcx.parent(def_id).unwrap())
1454 Res::Def(_, def_id) => tcx.generics_of(def_id),
1455 Res::Err => return Some(tcx.types.err),
1456 _ if !fail => return None,
1458 tcx.sess.delay_span_bug(
1461 "unexpected const parent path def {:?}",
1465 return Some(tcx.types.err);
1469 generics.params.iter()
1471 if let ty::GenericParamDefKind::Const = param.kind {
1478 .map(|param| tcx.type_of(param.def_id))
1479 // This is no generic parameter associated with the arg. This is
1480 // probably from an extra arg where one is not needed.
1481 .unwrap_or(tcx.types.err)
1486 tcx.sess.delay_span_bug(
1489 "unexpected const parent path {:?}",
1493 return Some(tcx.types.err);
1501 tcx.sess.delay_span_bug(
1504 "unexpected const parent in type_of_def_id(): {:?}", x
1512 Node::GenericParam(param) => match ¶m.kind {
1513 hir::GenericParamKind::Type { default: Some(ref ty), .. } => icx.to_ty(ty),
1514 hir::GenericParamKind::Const { ty: ref hir_ty, .. } => {
1515 let ty = icx.to_ty(hir_ty);
1516 if !tcx.features().const_compare_raw_pointers {
1517 let err = match ty.peel_refs().kind {
1518 ty::FnPtr(_) => Some("function pointers"),
1519 ty::RawPtr(_) => Some("raw pointers"),
1522 if let Some(unsupported_type) = err {
1523 feature_gate::emit_feature_err(
1524 &tcx.sess.parse_sess,
1525 sym::const_compare_raw_pointers,
1527 feature_gate::GateIssue::Language,
1529 "using {} as const generic parameters is unstable",
1535 if ty::search_for_structural_match_violation(
1536 param.hir_id, param.span, tcx, ty).is_some()
1542 "the types of const generic parameters must derive `PartialEq` and `Eq`",
1545 format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
1554 bug!("unexpected non-type Node::GenericParam: {:?}", x)
1562 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1567 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1568 use rustc::hir::{ImplItem, Item, TraitItem};
1570 debug!("find_opaque_ty_constraints({:?})", def_id);
1572 struct ConstraintLocator<'tcx> {
1575 // (first found type span, actual type, mapping from the opaque type's generic
1576 // parameters to the concrete type's generic parameters)
1578 // The mapping is an index for each use site of a generic parameter in the concrete type
1580 // The indices index into the generic parameters on the opaque type.
1581 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1584 impl ConstraintLocator<'tcx> {
1585 fn check(&mut self, def_id: DefId) {
1586 // Don't try to check items that cannot possibly constrain the type.
1587 if !self.tcx.has_typeck_tables(def_id) {
1589 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1597 .typeck_tables_of(def_id)
1598 .concrete_opaque_types
1600 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1602 "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1608 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1609 let span = self.tcx.def_span(def_id);
1610 // used to quickly look up the position of a generic parameter
1611 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1612 // Skipping binder is ok, since we only use this to find generic parameters and
1614 for (idx, subst) in substs.iter().enumerate() {
1615 if let GenericArgKind::Type(ty) = subst.unpack() {
1616 if let ty::Param(p) = ty.kind {
1617 if index_map.insert(p, idx).is_some() {
1618 // There was already an entry for `p`, meaning a generic parameter
1620 self.tcx.sess.span_err(
1623 "defining opaque type use restricts opaque \
1624 type by using the generic parameter `{}` twice",
1631 self.tcx.sess.delay_span_bug(
1634 "non-defining opaque ty use in defining scope: {:?}, {:?}",
1635 concrete_type, substs,
1641 // Compute the index within the opaque type for each generic parameter used in
1642 // the concrete type.
1643 let indices = concrete_type
1644 .subst(self.tcx, substs)
1646 .filter_map(|t| match &t.kind {
1647 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1650 let is_param = |ty: Ty<'_>| match ty.kind {
1651 ty::Param(_) => true,
1654 if !substs.types().all(is_param) {
1655 self.tcx.sess.span_err(
1657 "defining opaque type use does not fully define opaque type",
1659 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1660 let mut ty = concrete_type.walk().fuse();
1661 let mut p_ty = prev_ty.walk().fuse();
1662 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.kind, &p.kind) {
1663 // Type parameters are equal to any other type parameter for the purpose of
1664 // concrete type equality, as it is possible to obtain the same type just
1665 // by passing matching parameters to a function.
1666 (ty::Param(_), ty::Param(_)) => true,
1669 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1670 debug!("find_opaque_ty_constraints: span={:?}", span);
1671 // Found different concrete types for the opaque type.
1672 let mut err = self.tcx.sess.struct_span_err(
1674 "concrete type differs from previous defining opaque type use",
1678 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1680 err.span_note(prev_span, "previous use here");
1682 } else if indices != *prev_indices {
1683 // Found "same" concrete types, but the generic parameter order differs.
1684 let mut err = self.tcx.sess.struct_span_err(
1686 "concrete type's generic parameters differ from previous defining use",
1688 use std::fmt::Write;
1689 let mut s = String::new();
1690 write!(s, "expected [").unwrap();
1691 let list = |s: &mut String, indices: &Vec<usize>| {
1692 let mut indices = indices.iter().cloned();
1693 if let Some(first) = indices.next() {
1694 write!(s, "`{}`", substs[first]).unwrap();
1696 write!(s, ", `{}`", substs[i]).unwrap();
1700 list(&mut s, prev_indices);
1701 write!(s, "], got [").unwrap();
1702 list(&mut s, &indices);
1703 write!(s, "]").unwrap();
1704 err.span_label(span, s);
1705 err.span_note(prev_span, "previous use here");
1709 self.found = Some((span, concrete_type, indices));
1713 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
1721 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1722 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1723 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1725 fn visit_item(&mut self, it: &'tcx Item) {
1726 debug!("find_existential_constraints: visiting {:?}", it);
1727 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1728 // The opaque type itself or its children are not within its reveal scope.
1729 if def_id != self.def_id {
1731 intravisit::walk_item(self, it);
1734 fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
1735 debug!("find_existential_constraints: visiting {:?}", it);
1736 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1737 // The opaque type itself or its children are not within its reveal scope.
1738 if def_id != self.def_id {
1740 intravisit::walk_impl_item(self, it);
1743 fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
1744 debug!("find_existential_constraints: visiting {:?}", it);
1745 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1747 intravisit::walk_trait_item(self, it);
1751 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1752 let scope = tcx.hir().get_defining_scope(hir_id);
1753 let mut locator = ConstraintLocator {
1759 debug!("find_opaque_ty_constraints: scope={:?}", scope);
1761 if scope == hir::CRATE_HIR_ID {
1762 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1764 debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
1765 match tcx.hir().get(scope) {
1766 // We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
1767 // This allows our visitor to process the defining item itself, causing
1768 // it to pick up any 'sibling' defining uses.
1770 // For example, this code:
1773 // type Blah = impl Debug;
1774 // let my_closure = || -> Blah { true };
1778 // requires us to explicitly process `foo()` in order
1779 // to notice the defining usage of `Blah`.
1780 Node::Item(ref it) => locator.visit_item(it),
1781 Node::ImplItem(ref it) => locator.visit_impl_item(it),
1782 Node::TraitItem(ref it) => locator.visit_trait_item(it),
1784 "{:?} is not a valid scope for an opaque type item",
1790 match locator.found {
1791 Some((_, ty, _)) => ty,
1793 let span = tcx.def_span(def_id);
1794 tcx.sess.span_err(span, "could not find defining uses");
1800 pub fn get_infer_ret_ty(output: &'_ hir::FunctionRetTy) -> Option<&hir::Ty> {
1801 if let hir::FunctionRetTy::Return(ref ty) = output {
1802 if let hir::TyKind::Infer = ty.kind {
1809 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1811 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(MethodSig { header, decl }, TraitMethod::Provided(_)),
1822 | ImplItem(hir::ImplItem {
1823 kind: ImplItemKind::Method(MethodSig { header, decl }, _),
1827 kind: ItemKind::Fn(decl, header, _, _),
1829 }) => match get_infer_ret_ty(&decl.output) {
1831 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1832 let mut diag = bad_placeholder_type(tcx, ty.span);
1833 let ret_ty = fn_sig.output();
1834 if ret_ty != tcx.types.err {
1835 diag.span_suggestion(
1837 "replace `_` with the correct return type",
1839 Applicability::MaybeIncorrect,
1843 ty::Binder::bind(fn_sig)
1845 None => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl)
1848 TraitItem(hir::TraitItem {
1849 kind: TraitItemKind::Method(MethodSig { header, decl }, _),
1852 AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl)
1855 ForeignItem(&hir::ForeignItem {
1856 kind: ForeignItemKind::Fn(ref fn_decl, _, _),
1859 let abi = tcx.hir().get_foreign_abi(hir_id);
1860 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1863 Ctor(data) | Variant(
1864 hir::Variant { data, .. }
1865 ) if data.ctor_hir_id().is_some() => {
1866 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1867 let inputs = data.fields()
1869 .map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1870 ty::Binder::bind(tcx.mk_fn_sig(
1874 hir::Unsafety::Normal,
1880 kind: hir::ExprKind::Closure(..),
1883 // Closure signatures are not like other function
1884 // signatures and cannot be accessed through `fn_sig`. For
1885 // example, a closure signature excludes the `self`
1886 // argument. In any case they are embedded within the
1887 // closure type as part of the `ClosureSubsts`.
1890 // the signature of a closure, you should use the
1891 // `closure_sig` method on the `ClosureSubsts`:
1893 // closure_substs.sig(def_id, tcx)
1895 // or, inside of an inference context, you can use
1897 // infcx.closure_sig(def_id, closure_substs)
1898 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1902 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1907 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1908 let icx = ItemCtxt::new(tcx, def_id);
1910 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1911 match tcx.hir().expect_item(hir_id).kind {
1912 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1913 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1914 let selfty = tcx.type_of(def_id);
1915 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1922 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1923 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1924 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1925 let item = tcx.hir().expect_item(hir_id);
1927 hir::ItemKind::Impl(_, hir::ImplPolarity::Negative, ..) => {
1928 if is_rustc_reservation {
1929 tcx.sess.span_err(item.span, "reservation impls can't be negative");
1931 ty::ImplPolarity::Negative
1933 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, None, _, _) => {
1934 if is_rustc_reservation {
1935 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1937 ty::ImplPolarity::Positive
1939 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, Some(_tr), _, _) => {
1940 if is_rustc_reservation {
1941 ty::ImplPolarity::Reservation
1943 ty::ImplPolarity::Positive
1946 ref item => bug!("impl_polarity: {:?} not an impl", item),
1950 /// Returns the early-bound lifetimes declared in this generics
1951 /// listing. For anything other than fns/methods, this is just all
1952 /// the lifetimes that are declared. For fns or methods, we have to
1953 /// screen out those that do not appear in any where-clauses etc using
1954 /// `resolve_lifetime::early_bound_lifetimes`.
1955 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1957 generics: &'a hir::Generics,
1958 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {
1962 .filter(move |param| match param.kind {
1963 GenericParamKind::Lifetime { .. } => {
1964 !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(
1976 ) -> ty::GenericPredicates<'_> {
1977 debug!("predicates_defined_on({:?})", def_id);
1978 let mut result = tcx.explicit_predicates_of(def_id);
1980 "predicates_defined_on: explicit_predicates_of({:?}) = {:?}",
1984 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1985 if !inferred_outlives.is_empty() {
1987 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1991 if result.predicates.is_empty() {
1992 result.predicates = inferred_outlives;
1994 result.predicates = tcx.arena.alloc_from_iter(
1995 result.predicates.iter().chain(inferred_outlives).copied(),
1999 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2003 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2004 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2005 /// `Self: Trait` predicates for traits.
2006 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2007 let mut result = tcx.predicates_defined_on(def_id);
2009 if tcx.is_trait(def_id) {
2010 // For traits, add `Self: Trait` predicate. This is
2011 // not part of the predicates that a user writes, but it
2012 // is something that one must prove in order to invoke a
2013 // method or project an associated type.
2015 // In the chalk setup, this predicate is not part of the
2016 // "predicates" for a trait item. But it is useful in
2017 // rustc because if you directly (e.g.) invoke a trait
2018 // method like `Trait::method(...)`, you must naturally
2019 // prove that the trait applies to the types that were
2020 // used, and adding the predicate into this list ensures
2021 // that this is done.
2022 let span = tcx.def_span(def_id);
2023 result.predicates = tcx.arena.alloc_from_iter(
2024 result.predicates.iter().copied().chain(
2025 std::iter::once((ty::TraitRef::identity(tcx, def_id).to_predicate(), span))
2029 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2033 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2034 /// N.B., this does not include any implied/inferred constraints.
2035 fn explicit_predicates_of(
2038 ) -> ty::GenericPredicates<'_> {
2040 use rustc_data_structures::fx::FxHashSet;
2042 debug!("explicit_predicates_of(def_id={:?})", def_id);
2044 /// A data structure with unique elements, which preserves order of insertion.
2045 /// Preserving the order of insertion is important here so as not to break
2046 /// compile-fail UI tests.
2047 // FIXME(eddyb) just use `IndexSet` from `indexmap`.
2048 struct UniquePredicates<'tcx> {
2049 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
2050 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
2053 impl<'tcx> UniquePredicates<'tcx> {
2057 uniques: FxHashSet::default(),
2061 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
2062 if self.uniques.insert(value) {
2063 self.predicates.push(value);
2067 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
2074 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
2075 Some(hir_id) => hir_id,
2076 None => return tcx.predicates_of(def_id),
2078 let node = tcx.hir().get(hir_id);
2080 let mut is_trait = None;
2081 let mut is_default_impl_trait = None;
2083 let icx = ItemCtxt::new(tcx, def_id);
2085 const NO_GENERICS: &hir::Generics = &hir::Generics::empty();
2087 let empty_trait_items = HirVec::new();
2089 let mut predicates = UniquePredicates::new();
2091 let ast_generics = match node {
2092 Node::TraitItem(item) => &item.generics,
2094 Node::ImplItem(item) => match item.kind {
2095 ImplItemKind::OpaqueTy(ref bounds) => {
2096 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2097 let opaque_ty = tcx.mk_opaque(def_id, substs);
2099 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2100 let bounds = AstConv::compute_bounds(
2104 SizedByDefault::Yes,
2105 tcx.def_span(def_id),
2108 predicates.extend(bounds.predicates(tcx, opaque_ty));
2111 _ => &item.generics,
2114 Node::Item(item) => {
2116 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
2117 if defaultness.is_default() {
2118 is_default_impl_trait = tcx.impl_trait_ref(def_id);
2122 ItemKind::Fn(.., ref generics, _)
2123 | ItemKind::TyAlias(_, ref generics)
2124 | ItemKind::Enum(_, ref generics)
2125 | ItemKind::Struct(_, ref generics)
2126 | ItemKind::Union(_, ref generics) => generics,
2128 ItemKind::Trait(_, _, ref generics, .., ref items) => {
2129 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
2132 ItemKind::TraitAlias(ref generics, _) => {
2133 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &empty_trait_items));
2136 ItemKind::OpaqueTy(OpaqueTy {
2142 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2143 let opaque_ty = tcx.mk_opaque(def_id, substs);
2145 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2146 let bounds = AstConv::compute_bounds(
2150 SizedByDefault::Yes,
2151 tcx.def_span(def_id),
2154 let bounds_predicates = bounds.predicates(tcx, opaque_ty);
2155 if impl_trait_fn.is_some() {
2157 return ty::GenericPredicates {
2159 predicates: tcx.arena.alloc_from_iter(bounds_predicates),
2162 // named opaque types
2163 predicates.extend(bounds_predicates);
2172 Node::ForeignItem(item) => match item.kind {
2173 ForeignItemKind::Static(..) => NO_GENERICS,
2174 ForeignItemKind::Fn(_, _, ref generics) => generics,
2175 ForeignItemKind::Type => NO_GENERICS,
2181 let generics = tcx.generics_of(def_id);
2182 let parent_count = generics.parent_count as u32;
2183 let has_own_self = generics.has_self && parent_count == 0;
2185 // Below we'll consider the bounds on the type parameters (including `Self`)
2186 // and the explicit where-clauses, but to get the full set of predicates
2187 // on a trait we need to add in the supertrait bounds and bounds found on
2188 // associated types.
2189 if let Some((_trait_ref, _)) = is_trait {
2190 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2193 // In default impls, we can assume that the self type implements
2194 // the trait. So in:
2196 // default impl Foo for Bar { .. }
2198 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2199 // (see below). Recall that a default impl is not itself an impl, but rather a
2200 // set of defaults that can be incorporated into another impl.
2201 if let Some(trait_ref) = is_default_impl_trait {
2202 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2205 // Collect the region predicates that were declared inline as
2206 // well. In the case of parameters declared on a fn or method, we
2207 // have to be careful to only iterate over early-bound regions.
2208 let mut index = parent_count + has_own_self as u32;
2209 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2210 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2211 def_id: tcx.hir().local_def_id(param.hir_id),
2213 name: param.name.ident().name,
2218 GenericParamKind::Lifetime { .. } => {
2219 param.bounds.iter().for_each(|bound| match bound {
2220 hir::GenericBound::Outlives(lt) => {
2221 let bound = AstConv::ast_region_to_region(&icx, <, None);
2222 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2223 predicates.push((outlives.to_predicate(), lt.span));
2232 // Collect the predicates that were written inline by the user on each
2233 // type parameter (e.g., `<T: Foo>`).
2234 for param in &ast_generics.params {
2235 if let GenericParamKind::Type { .. } = param.kind {
2236 let name = param.name.ident().name;
2237 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2240 let sized = SizedByDefault::Yes;
2241 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2242 predicates.extend(bounds.predicates(tcx, param_ty));
2246 // Add in the bounds that appear in the where-clause.
2247 let where_clause = &ast_generics.where_clause;
2248 for predicate in &where_clause.predicates {
2250 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2251 let ty = icx.to_ty(&bound_pred.bounded_ty);
2253 // Keep the type around in a dummy predicate, in case of no bounds.
2254 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2255 // is still checked for WF.
2256 if bound_pred.bounds.is_empty() {
2257 if let ty::Param(_) = ty.kind {
2258 // This is a `where T:`, which can be in the HIR from the
2259 // transformation that moves `?Sized` to `T`'s declaration.
2260 // We can skip the predicate because type parameters are
2261 // trivially WF, but also we *should*, to avoid exposing
2262 // users who never wrote `where Type:,` themselves, to
2263 // compiler/tooling bugs from not handling WF predicates.
2265 let span = bound_pred.bounded_ty.span;
2266 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2268 (ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
2273 for bound in bound_pred.bounds.iter() {
2275 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2276 let mut bounds = Bounds::default();
2277 let _ = AstConv::instantiate_poly_trait_ref(
2283 predicates.extend(bounds.predicates(tcx, ty));
2286 &hir::GenericBound::Outlives(ref lifetime) => {
2287 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2288 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2289 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2295 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2296 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2297 predicates.extend(region_pred.bounds.iter().map(|bound| {
2298 let (r2, span) = match bound {
2299 hir::GenericBound::Outlives(lt) => {
2300 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2304 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2306 (ty::Predicate::RegionOutlives(pred), span)
2310 &hir::WherePredicate::EqPredicate(..) => {
2316 // Add predicates from associated type bounds.
2317 if let Some((self_trait_ref, trait_items)) = is_trait {
2318 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2319 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2320 let bounds = match trait_item.kind {
2321 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2322 _ => return Vec::new().into_iter()
2326 tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id),
2327 self_trait_ref.substs);
2329 let bounds = AstConv::compute_bounds(
2330 &ItemCtxt::new(tcx, def_id),
2333 SizedByDefault::Yes,
2337 bounds.predicates(tcx, assoc_ty).into_iter()
2341 let mut predicates = predicates.predicates;
2343 // Subtle: before we store the predicates into the tcx, we
2344 // sort them so that predicates like `T: Foo<Item=U>` come
2345 // before uses of `U`. This avoids false ambiguity errors
2346 // in trait checking. See `setup_constraining_predicates`
2348 if let Node::Item(&Item {
2349 kind: ItemKind::Impl(..),
2353 let self_ty = tcx.type_of(def_id);
2354 let trait_ref = tcx.impl_trait_ref(def_id);
2355 cgp::setup_constraining_predicates(
2359 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2363 let result = ty::GenericPredicates {
2364 parent: generics.parent,
2365 predicates: tcx.arena.alloc_from_iter(predicates),
2367 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2371 /// Converts a specific `GenericBound` from the AST into a set of
2372 /// predicates that apply to the self type. A vector is returned
2373 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2374 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2375 /// and `<T as Bar>::X == i32`).
2376 fn predicates_from_bound<'tcx>(
2377 astconv: &dyn AstConv<'tcx>,
2379 bound: &'tcx hir::GenericBound,
2380 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2382 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2383 let mut bounds = Bounds::default();
2384 let _ = astconv.instantiate_poly_trait_ref(
2389 bounds.predicates(astconv.tcx(), param_ty)
2391 hir::GenericBound::Outlives(ref lifetime) => {
2392 let region = astconv.ast_region_to_region(lifetime, None);
2393 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2394 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2396 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2400 fn compute_sig_of_foreign_fn_decl<'tcx>(
2403 decl: &'tcx hir::FnDecl,
2405 ) -> ty::PolyFnSig<'tcx> {
2406 let unsafety = if abi == abi::Abi::RustIntrinsic {
2407 intrinsic_operation_unsafety(&*tcx.item_name(def_id).as_str())
2409 hir::Unsafety::Unsafe
2411 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2413 // Feature gate SIMD types in FFI, since I am not sure that the
2414 // ABIs are handled at all correctly. -huonw
2415 if abi != abi::Abi::RustIntrinsic
2416 && abi != abi::Abi::PlatformIntrinsic
2417 && !tcx.features().simd_ffi
2419 let check = |ast_ty: &hir::Ty, ty: Ty<'_>| {
2425 "use of SIMD type `{}` in FFI is highly experimental and \
2426 may result in invalid code",
2427 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2430 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2434 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2437 if let hir::Return(ref ty) = decl.output {
2438 check(&ty, *fty.output().skip_binder())
2445 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2446 match tcx.hir().get_if_local(def_id) {
2447 Some(Node::ForeignItem(..)) => true,
2449 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2453 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2454 match tcx.hir().get_if_local(def_id) {
2455 Some(Node::Item(&hir::Item {
2456 kind: hir::ItemKind::Static(_, mutbl, _), ..
2458 Some(Node::ForeignItem( &hir::ForeignItem {
2459 kind: hir::ForeignItemKind::Static(_, mutbl), ..
2462 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2466 fn from_target_feature(
2469 attr: &ast::Attribute,
2470 whitelist: &FxHashMap<String, Option<Symbol>>,
2471 target_features: &mut Vec<Symbol>,
2473 let list = match attr.meta_item_list() {
2477 let bad_item = |span| {
2478 let msg = "malformed `target_feature` attribute input";
2479 let code = "enable = \"..\"".to_owned();
2480 tcx.sess.struct_span_err(span, &msg)
2481 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2484 let rust_features = tcx.features();
2486 // Only `enable = ...` is accepted in the meta-item list.
2487 if !item.check_name(sym::enable) {
2488 bad_item(item.span());
2492 // Must be of the form `enable = "..."` (a string).
2493 let value = match item.value_str() {
2494 Some(value) => value,
2496 bad_item(item.span());
2501 // We allow comma separation to enable multiple features.
2502 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2503 // Only allow whitelisted features per platform.
2504 let feature_gate = match whitelist.get(feature) {
2508 "the feature named `{}` is not valid for this target",
2511 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2514 format!("`{}` is not valid for this target", feature),
2516 if feature.starts_with("+") {
2517 let valid = whitelist.contains_key(&feature[1..]);
2519 err.help("consider removing the leading `+` in the feature name");
2527 // Only allow features whose feature gates have been enabled.
2528 let allowed = match feature_gate.as_ref().map(|s| *s) {
2529 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2530 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2531 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2532 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2533 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2534 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2535 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2536 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2537 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2538 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2539 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2540 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2541 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2542 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2543 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2544 Some(name) => bug!("unknown target feature gate {}", name),
2547 if !allowed && id.is_local() {
2548 feature_gate::emit_feature_err(
2549 &tcx.sess.parse_sess,
2550 feature_gate.unwrap(),
2552 feature_gate::GateIssue::Language,
2553 &format!("the target feature `{}` is currently unstable", feature),
2556 Some(Symbol::intern(feature))
2561 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2562 use rustc::mir::mono::Linkage::*;
2564 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2565 // applicable to variable declarations and may not really make sense for
2566 // Rust code in the first place but whitelist them anyway and trust that
2567 // the user knows what s/he's doing. Who knows, unanticipated use cases
2568 // may pop up in the future.
2570 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2571 // and don't have to be, LLVM treats them as no-ops.
2573 "appending" => Appending,
2574 "available_externally" => AvailableExternally,
2576 "extern_weak" => ExternalWeak,
2577 "external" => External,
2578 "internal" => Internal,
2579 "linkonce" => LinkOnceAny,
2580 "linkonce_odr" => LinkOnceODR,
2581 "private" => Private,
2583 "weak_odr" => WeakODR,
2585 let span = tcx.hir().span_if_local(def_id);
2586 if let Some(span) = span {
2587 tcx.sess.span_fatal(span, "invalid linkage specified")
2590 .fatal(&format!("invalid linkage specified: {}", name))
2596 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2597 let attrs = tcx.get_attrs(id);
2599 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2601 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2603 let mut inline_span = None;
2604 let mut link_ordinal_span = None;
2605 for attr in attrs.iter() {
2606 if attr.check_name(sym::cold) {
2607 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2608 } else if attr.check_name(sym::rustc_allocator) {
2609 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2610 } else if attr.check_name(sym::unwind) {
2611 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2612 } else if attr.check_name(sym::ffi_returns_twice) {
2613 if tcx.is_foreign_item(id) {
2614 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2616 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2621 "`#[ffi_returns_twice]` may only be used on foreign functions"
2624 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2625 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2626 } else if attr.check_name(sym::naked) {
2627 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2628 } else if attr.check_name(sym::no_mangle) {
2629 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2630 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2631 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2632 } else if attr.check_name(sym::no_debug) {
2633 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2634 } else if attr.check_name(sym::used) {
2635 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2636 } else if attr.check_name(sym::thread_local) {
2637 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2638 } else if attr.check_name(sym::track_caller) {
2639 if tcx.fn_sig(id).abi() != abi::Abi::Rust {
2644 "rust ABI is required to use `#[track_caller]`"
2647 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2648 } else if attr.check_name(sym::export_name) {
2649 if let Some(s) = attr.value_str() {
2650 if s.as_str().contains("\0") {
2651 // `#[export_name = ...]` will be converted to a null-terminated string,
2652 // so it may not contain any null characters.
2657 "`export_name` may not contain null characters"
2660 codegen_fn_attrs.export_name = Some(s);
2662 } else if attr.check_name(sym::target_feature) {
2663 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2664 let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
2665 tcx.sess.struct_span_err(attr.span, msg)
2666 .span_label(attr.span, "can only be applied to `unsafe` functions")
2667 .span_label(tcx.def_span(id), "not an `unsafe` function")
2670 from_target_feature(
2675 &mut codegen_fn_attrs.target_features,
2677 } else if attr.check_name(sym::linkage) {
2678 if let Some(val) = attr.value_str() {
2679 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2681 } else if attr.check_name(sym::link_section) {
2682 if let Some(val) = attr.value_str() {
2683 if val.as_str().bytes().any(|b| b == 0) {
2685 "illegal null byte in link_section \
2689 tcx.sess.span_err(attr.span, &msg);
2691 codegen_fn_attrs.link_section = Some(val);
2694 } else if attr.check_name(sym::link_name) {
2695 codegen_fn_attrs.link_name = attr.value_str();
2696 } else if attr.check_name(sym::link_ordinal) {
2697 link_ordinal_span = Some(attr.span);
2698 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2699 codegen_fn_attrs.link_ordinal = ordinal;
2704 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2705 if attr.path != sym::inline {
2708 match attr.meta().map(|i| i.kind) {
2709 Some(MetaItemKind::Word) => {
2713 Some(MetaItemKind::List(ref items)) => {
2715 inline_span = Some(attr.span);
2716 if items.len() != 1 {
2718 tcx.sess.diagnostic(),
2721 "expected one argument"
2724 } else if list_contains_name(&items[..], sym::always) {
2726 } else if list_contains_name(&items[..], sym::never) {
2730 tcx.sess.diagnostic(),
2739 Some(MetaItemKind::NameValue(_)) => ia,
2744 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2745 if attr.path != sym::optimize {
2748 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2749 match attr.meta().map(|i| i.kind) {
2750 Some(MetaItemKind::Word) => {
2751 err(attr.span, "expected one argument");
2754 Some(MetaItemKind::List(ref items)) => {
2756 inline_span = Some(attr.span);
2757 if items.len() != 1 {
2758 err(attr.span, "expected one argument");
2760 } else if list_contains_name(&items[..], sym::size) {
2762 } else if list_contains_name(&items[..], sym::speed) {
2765 err(items[0].span(), "invalid argument");
2769 Some(MetaItemKind::NameValue(_)) => ia,
2774 // If a function uses #[target_feature] it can't be inlined into general
2775 // purpose functions as they wouldn't have the right target features
2776 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2779 if codegen_fn_attrs.target_features.len() > 0 {
2780 if codegen_fn_attrs.inline == InlineAttr::Always {
2781 if let Some(span) = inline_span {
2784 "cannot use `#[inline(always)]` with \
2785 `#[target_feature]`",
2791 // Weak lang items have the same semantics as "std internal" symbols in the
2792 // sense that they're preserved through all our LTO passes and only
2793 // strippable by the linker.
2795 // Additionally weak lang items have predetermined symbol names.
2796 if tcx.is_weak_lang_item(id) {
2797 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2799 if let Some(name) = weak_lang_items::link_name(&attrs) {
2800 codegen_fn_attrs.export_name = Some(name);
2801 codegen_fn_attrs.link_name = Some(name);
2803 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2805 // Internal symbols to the standard library all have no_mangle semantics in
2806 // that they have defined symbol names present in the function name. This
2807 // also applies to weak symbols where they all have known symbol names.
2808 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2809 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2815 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
2816 use syntax::ast::{Lit, LitIntType, LitKind};
2817 let meta_item_list = attr.meta_item_list();
2818 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
2819 let sole_meta_list = match meta_item_list {
2820 Some([item]) => item.literal(),
2823 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
2824 if *ordinal <= std::usize::MAX as u128 {
2825 Some(*ordinal as usize)
2828 "ordinal value in `link_ordinal` is too large: `{}`",
2831 tcx.sess.struct_span_err(attr.span, &msg)
2832 .note("the value may not exceed `std::usize::MAX`")
2837 tcx.sess.struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
2838 .note("an unsuffixed integer value, e.g., `1`, is expected")
2844 fn check_link_name_xor_ordinal(
2846 codegen_fn_attrs: &CodegenFnAttrs,
2847 inline_span: Option<Span>,
2849 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
2852 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
2853 if let Some(span) = inline_span {
2854 tcx.sess.span_err(span, msg);