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::intrisic_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::UnpackedKind;
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::{InternedString, 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};
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.node {
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)
186 -> &'tcx ty::GenericPredicates<'tcx> {
189 .type_param_predicates((self.item_def_id, def_id))
194 _: Option<&ty::GenericParamDef>,
196 ) -> Option<ty::Region<'tcx>> {
200 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
201 bad_placeholder_type(self.tcx(), span).emit();
209 _: Option<&ty::GenericParamDef>,
211 ) -> &'tcx Const<'tcx> {
212 bad_placeholder_type(self.tcx(), span).emit();
214 self.tcx().consts.err
217 fn projected_ty_from_poly_trait_ref(
221 poly_trait_ref: ty::PolyTraitRef<'tcx>,
223 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
224 self.tcx().mk_projection(item_def_id, trait_ref.substs)
226 // There are no late-bound regions; we can just ignore the binder.
231 "cannot extract an associated type from a higher-ranked trait bound \
238 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
239 // Types in item signatures are not normalized to avoid undue dependencies.
243 fn set_tainted_by_errors(&self) {
244 // There's no obvious place to track this, so just let it go.
247 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
248 // There's no place to record types from signatures?
252 /// Returns the predicates defined on `item_def_id` of the form
253 /// `X: Foo` where `X` is the type parameter `def_id`.
254 fn type_param_predicates(
256 (item_def_id, def_id): (DefId, DefId),
257 ) -> &ty::GenericPredicates<'_> {
260 // In the AST, bounds can derive from two places. Either
261 // written inline like `<T: Foo>` or in a where-clause like
264 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
265 let param_owner = tcx.hir().ty_param_owner(param_id);
266 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
267 let generics = tcx.generics_of(param_owner_def_id);
268 let index = generics.param_def_id_to_index[&def_id];
269 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id).as_interned_str());
271 // Don't look for bounds where the type parameter isn't in scope.
272 let parent = if item_def_id == param_owner_def_id {
275 tcx.generics_of(item_def_id).parent
278 let result = parent.map_or(&tcx.common.empty_predicates, |parent| {
279 let icx = ItemCtxt::new(tcx, parent);
280 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
282 let mut extend = None;
284 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
285 let ast_generics = match tcx.hir().get(item_hir_id) {
286 Node::TraitItem(item) => &item.generics,
288 Node::ImplItem(item) => &item.generics,
290 Node::Item(item) => {
292 ItemKind::Fn(.., ref generics, _)
293 | ItemKind::Impl(_, _, _, ref generics, ..)
294 | ItemKind::TyAlias(_, ref generics)
295 | ItemKind::OpaqueTy(OpaqueTy {
300 | ItemKind::Enum(_, ref generics)
301 | ItemKind::Struct(_, ref generics)
302 | ItemKind::Union(_, ref generics) => generics,
303 ItemKind::Trait(_, _, ref generics, ..) => {
304 // Implied `Self: Trait` and supertrait bounds.
305 if param_id == item_hir_id {
306 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
307 extend = Some((identity_trait_ref.to_predicate(), item.span));
315 Node::ForeignItem(item) => match item.node {
316 ForeignItemKind::Fn(_, _, ref generics) => generics,
323 let icx = ItemCtxt::new(tcx, item_def_id);
324 let mut result = (*result).clone();
325 result.predicates.extend(extend.into_iter());
326 result.predicates.extend(
327 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
329 .filter(|(predicate, _)| {
331 ty::Predicate::Trait(ref data) => data.skip_binder().self_ty().is_param(index),
336 tcx.arena.alloc(result)
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.node {
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.node {
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.node {
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.node {
490 hir::TraitItemKind::Const(..)
491 | hir::TraitItemKind::Type(_, Some(_))
492 | hir::TraitItemKind::Method(..) => {
494 if let hir::TraitItemKind::Method(..) = trait_item.node {
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).node {
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.node {
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.node {
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: Vec<_> = superbounds1.into_iter().chain(superbounds2).collect();
737 // Now require that immediate supertraits are converted,
738 // which will, in turn, reach indirect supertraits.
739 for &(pred, span) in &superbounds {
740 debug!("superbound: {:?}", pred);
741 if let ty::Predicate::Trait(bound) = pred {
742 tcx.at(span).super_predicates_of(bound.def_id());
746 tcx.arena.alloc(ty::GenericPredicates {
748 predicates: superbounds,
752 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
753 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
754 let item = tcx.hir().expect_item(hir_id);
756 let (is_auto, unsafety) = match item.node {
757 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
758 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
759 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
762 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
763 if paren_sugar && !tcx.features().unboxed_closures {
764 let mut err = tcx.sess.struct_span_err(
766 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
767 which traits can use parenthetical notation",
771 "add `#![feature(unboxed_closures)]` to \
772 the crate attributes to use it"
777 let is_marker = tcx.has_attr(def_id, sym::marker);
778 let def_path_hash = tcx.def_path_hash(def_id);
779 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
783 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
784 struct LateBoundRegionsDetector<'tcx> {
786 outer_index: ty::DebruijnIndex,
787 has_late_bound_regions: Option<Span>,
790 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
791 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
792 NestedVisitorMap::None
795 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
796 if self.has_late_bound_regions.is_some() {
800 hir::TyKind::BareFn(..) => {
801 self.outer_index.shift_in(1);
802 intravisit::walk_ty(self, ty);
803 self.outer_index.shift_out(1);
805 _ => intravisit::walk_ty(self, ty),
809 fn visit_poly_trait_ref(
811 tr: &'tcx hir::PolyTraitRef,
812 m: hir::TraitBoundModifier,
814 if self.has_late_bound_regions.is_some() {
817 self.outer_index.shift_in(1);
818 intravisit::walk_poly_trait_ref(self, tr, m);
819 self.outer_index.shift_out(1);
822 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
823 if self.has_late_bound_regions.is_some() {
827 match self.tcx.named_region(lt.hir_id) {
828 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
829 Some(rl::Region::LateBound(debruijn, _, _))
830 | Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
831 Some(rl::Region::LateBound(..))
832 | Some(rl::Region::LateBoundAnon(..))
833 | Some(rl::Region::Free(..))
835 self.has_late_bound_regions = Some(lt.span);
841 fn has_late_bound_regions<'tcx>(
843 generics: &'tcx hir::Generics,
844 decl: &'tcx hir::FnDecl,
846 let mut visitor = LateBoundRegionsDetector {
848 outer_index: ty::INNERMOST,
849 has_late_bound_regions: None,
851 for param in &generics.params {
852 if let GenericParamKind::Lifetime { .. } = param.kind {
853 if tcx.is_late_bound(param.hir_id) {
854 return Some(param.span);
858 visitor.visit_fn_decl(decl);
859 visitor.has_late_bound_regions
863 Node::TraitItem(item) => match item.node {
864 hir::TraitItemKind::Method(ref sig, _) => {
865 has_late_bound_regions(tcx, &item.generics, &sig.decl)
869 Node::ImplItem(item) => match item.node {
870 hir::ImplItemKind::Method(ref sig, _) => {
871 has_late_bound_regions(tcx, &item.generics, &sig.decl)
875 Node::ForeignItem(item) => match item.node {
876 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
877 has_late_bound_regions(tcx, generics, fn_decl)
881 Node::Item(item) => match item.node {
882 hir::ItemKind::Fn(ref fn_decl, .., ref generics, _) => {
883 has_late_bound_regions(tcx, generics, fn_decl)
891 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
894 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
896 let node = tcx.hir().get(hir_id);
897 let parent_def_id = match node {
898 Node::ImplItem(_) | Node::TraitItem(_) | Node::Variant(_) |
899 Node::Ctor(..) | Node::Field(_) => {
900 let parent_id = tcx.hir().get_parent_item(hir_id);
901 Some(tcx.hir().local_def_id(parent_id))
903 // FIXME(#43408) enable this in all cases when we get lazy normalization.
904 Node::AnonConst(&anon_const) => {
905 // HACK(eddyb) this provides the correct generics when the workaround
906 // for a const parameter `AnonConst` is being used elsewhere, as then
907 // there won't be the kind of cyclic dependency blocking #43408.
908 let expr = &tcx.hir().body(anon_const.body).value;
909 let icx = ItemCtxt::new(tcx, def_id);
910 if AstConv::const_param_def_id(&icx, expr).is_some() {
911 let parent_id = tcx.hir().get_parent_item(hir_id);
912 Some(tcx.hir().local_def_id(parent_id))
917 Node::Expr(&hir::Expr {
918 node: hir::ExprKind::Closure(..),
920 }) => Some(tcx.closure_base_def_id(def_id)),
921 Node::Item(item) => match item.node {
922 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => impl_trait_fn,
928 let mut opt_self = None;
929 let mut allow_defaults = false;
931 let no_generics = hir::Generics::empty();
932 let ast_generics = match node {
933 Node::TraitItem(item) => &item.generics,
935 Node::ImplItem(item) => &item.generics,
937 Node::Item(item) => {
939 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
943 ItemKind::TyAlias(_, ref generics)
944 | ItemKind::Enum(_, ref generics)
945 | ItemKind::Struct(_, ref generics)
946 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
947 | ItemKind::Union(_, ref generics) => {
948 allow_defaults = true;
952 ItemKind::Trait(_, _, ref generics, ..)
953 | ItemKind::TraitAlias(ref generics, ..) => {
954 // Add in the self type parameter.
956 // Something of a hack: use the node id for the trait, also as
957 // the node id for the Self type parameter.
958 let param_id = item.hir_id;
960 opt_self = Some(ty::GenericParamDef {
962 name: kw::SelfUpper.as_interned_str(),
963 def_id: tcx.hir().local_def_id(param_id),
964 pure_wrt_drop: false,
965 kind: ty::GenericParamDefKind::Type {
967 object_lifetime_default: rl::Set1::Empty,
972 allow_defaults = true;
980 Node::ForeignItem(item) => match item.node {
981 ForeignItemKind::Static(..) => &no_generics,
982 ForeignItemKind::Fn(_, _, ref generics) => generics,
983 ForeignItemKind::Type => &no_generics,
989 let has_self = opt_self.is_some();
990 let mut parent_has_self = false;
991 let mut own_start = has_self as u32;
992 let parent_count = parent_def_id.map_or(0, |def_id| {
993 let generics = tcx.generics_of(def_id);
994 assert_eq!(has_self, false);
995 parent_has_self = generics.has_self;
996 own_start = generics.count() as u32;
997 generics.parent_count + generics.params.len()
1000 let mut params: Vec<_> = opt_self.into_iter().collect();
1002 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1006 .map(|(i, param)| ty::GenericParamDef {
1007 name: param.name.ident().as_interned_str(),
1008 index: own_start + i as u32,
1009 def_id: tcx.hir().local_def_id(param.hir_id),
1010 pure_wrt_drop: param.pure_wrt_drop,
1011 kind: ty::GenericParamDefKind::Lifetime,
1015 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1017 // Now create the real type parameters.
1018 let type_start = own_start - has_self as u32 + params.len() as u32;
1024 .filter_map(|param| {
1025 let kind = match param.kind {
1026 GenericParamKind::Type {
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 { .. } => {
1054 ty::GenericParamDefKind::Const
1059 let param_def = ty::GenericParamDef {
1060 index: type_start + i as u32,
1061 name: param.name.ident().as_interned_str(),
1062 def_id: tcx.hir().local_def_id(param.hir_id),
1063 pure_wrt_drop: param.pure_wrt_drop,
1071 // provide junk type parameter defs - the only place that
1072 // cares about anything but the length is instantiation,
1073 // and we don't do that for closures.
1074 if let Node::Expr(&hir::Expr {
1075 node: hir::ExprKind::Closure(.., gen),
1079 let dummy_args = if gen.is_some() {
1080 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1082 &["<closure_kind>", "<closure_signature>"][..]
1089 .map(|(i, &arg)| ty::GenericParamDef {
1090 index: type_start + i as u32,
1091 name: InternedString::intern(arg),
1093 pure_wrt_drop: false,
1094 kind: ty::GenericParamDefKind::Type {
1096 object_lifetime_default: rl::Set1::Empty,
1102 if let Some(upvars) = tcx.upvars(def_id) {
1103 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1104 ty::GenericParamDef {
1105 index: type_start + i,
1106 name: InternedString::intern("<upvar>"),
1108 pure_wrt_drop: false,
1109 kind: ty::GenericParamDefKind::Type {
1111 object_lifetime_default: rl::Set1::Empty,
1119 let param_def_id_to_index = params
1121 .map(|param| (param.def_id, param.index))
1124 tcx.arena.alloc(ty::Generics {
1125 parent: parent_def_id,
1128 param_def_id_to_index,
1129 has_self: has_self || parent_has_self,
1130 has_late_bound_regions: has_late_bound_regions(tcx, node),
1134 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
1139 "associated types are not yet supported in inherent impls (see #8995)"
1143 fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1144 checked_type_of(tcx, def_id, true).unwrap()
1147 fn infer_placeholder_type(
1150 body_id: hir::BodyId,
1153 let ty = tcx.typeck_tables_of(def_id).node_type(body_id.hir_id);
1154 let mut diag = bad_placeholder_type(tcx, span);
1155 if ty != tcx.types.err {
1156 diag.span_suggestion(
1158 "replace `_` with the correct type",
1160 Applicability::MaybeIncorrect,
1167 /// Same as [`type_of`] but returns [`Option`] instead of failing.
1169 /// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
1170 /// you'd better just call [`type_of`] directly.
1171 pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<'_>> {
1174 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1175 Some(hir_id) => hir_id,
1180 bug!("invalid node");
1184 let icx = ItemCtxt::new(tcx, def_id);
1186 Some(match tcx.hir().get(hir_id) {
1187 Node::TraitItem(item) => match item.node {
1188 TraitItemKind::Method(..) => {
1189 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1190 tcx.mk_fn_def(def_id, substs)
1192 TraitItemKind::Const(ref ty, body_id) => {
1193 body_id.and_then(|body_id| {
1194 if let hir::TyKind::Infer = ty.node {
1195 Some(infer_placeholder_type(tcx, def_id, body_id, ty.span))
1199 }).unwrap_or_else(|| icx.to_ty(ty))
1201 TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1202 TraitItemKind::Type(_, None) => {
1206 span_bug!(item.span, "associated type missing default");
1210 Node::ImplItem(item) => match item.node {
1211 ImplItemKind::Method(..) => {
1212 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1213 tcx.mk_fn_def(def_id, substs)
1215 ImplItemKind::Const(ref ty, body_id) => {
1216 if let hir::TyKind::Infer = ty.node {
1217 infer_placeholder_type(tcx, def_id, body_id, ty.span)
1222 ImplItemKind::OpaqueTy(_) => {
1224 .impl_trait_ref(tcx.hir().get_parent_did(hir_id))
1227 report_assoc_ty_on_inherent_impl(tcx, item.span);
1230 find_opaque_ty_constraints(tcx, def_id)
1232 ImplItemKind::TyAlias(ref ty) => {
1234 .impl_trait_ref(tcx.hir().get_parent_did(hir_id))
1237 report_assoc_ty_on_inherent_impl(tcx, item.span);
1244 Node::Item(item) => {
1246 ItemKind::Static(ref ty, .., body_id)
1247 | ItemKind::Const(ref ty, body_id) => {
1248 if let hir::TyKind::Infer = ty.node {
1249 infer_placeholder_type(tcx, def_id, body_id, ty.span)
1254 ItemKind::TyAlias(ref ty, _)
1255 | ItemKind::Impl(.., ref ty, _) => icx.to_ty(ty),
1256 ItemKind::Fn(..) => {
1257 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1258 tcx.mk_fn_def(def_id, substs)
1260 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1261 let def = tcx.adt_def(def_id);
1262 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1263 tcx.mk_adt(def, substs)
1265 ItemKind::OpaqueTy(hir::OpaqueTy {
1266 impl_trait_fn: None,
1268 }) => find_opaque_ty_constraints(tcx, def_id),
1269 // Opaque types desugared from `impl Trait`.
1270 ItemKind::OpaqueTy(hir::OpaqueTy {
1271 impl_trait_fn: Some(owner),
1274 tcx.typeck_tables_of(owner)
1275 .concrete_opaque_types
1277 .map(|opaque| opaque.concrete_type)
1278 .unwrap_or_else(|| {
1279 // This can occur if some error in the
1280 // owner fn prevented us from populating
1281 // the `concrete_opaque_types` table.
1282 tcx.sess.delay_span_bug(
1285 "owner {:?} has no opaque type for {:?} in its tables",
1293 | ItemKind::TraitAlias(..)
1295 | ItemKind::ForeignMod(..)
1296 | ItemKind::GlobalAsm(..)
1297 | ItemKind::ExternCrate(..)
1298 | ItemKind::Use(..) => {
1304 "compute_type_of_item: unexpected item type: {:?}",
1311 Node::ForeignItem(foreign_item) => match foreign_item.node {
1312 ForeignItemKind::Fn(..) => {
1313 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1314 tcx.mk_fn_def(def_id, substs)
1316 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1317 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1320 Node::Ctor(&ref def) | Node::Variant(
1321 hir::Variant { data: ref def, .. }
1323 VariantData::Unit(..) | VariantData::Struct(..) => {
1324 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1326 VariantData::Tuple(..) => {
1327 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1328 tcx.mk_fn_def(def_id, substs)
1332 Node::Field(field) => icx.to_ty(&field.ty),
1334 Node::Expr(&hir::Expr {
1335 node: hir::ExprKind::Closure(.., gen),
1339 return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
1342 let substs = ty::ClosureSubsts {
1343 substs: InternalSubsts::identity_for_item(tcx, def_id),
1346 tcx.mk_closure(def_id, substs)
1349 Node::AnonConst(_) => {
1350 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1353 node: hir::TyKind::Array(_, ref constant),
1356 | Node::Ty(&hir::Ty {
1357 node: hir::TyKind::Typeof(ref constant),
1360 | Node::Expr(&hir::Expr {
1361 node: ExprKind::Repeat(_, ref constant),
1363 }) if constant.hir_id == hir_id =>
1368 Node::Variant(Variant {
1369 disr_expr: Some(ref e),
1371 }) if e.hir_id == hir_id =>
1373 tcx.adt_def(tcx.hir().get_parent_did(hir_id))
1379 Node::Ty(&hir::Ty { node: hir::TyKind::Path(_), .. }) |
1380 Node::Expr(&hir::Expr { node: ExprKind::Struct(..), .. }) |
1381 Node::Expr(&hir::Expr { node: ExprKind::Path(_), .. }) |
1382 Node::TraitRef(..) => {
1383 let path = match parent_node {
1385 node: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1388 | Node::Expr(&hir::Expr {
1389 node: ExprKind::Path(QPath::Resolved(_, ref path)),
1394 Node::Expr(&hir::Expr { node: ExprKind::Struct(ref path, ..), .. }) => {
1395 if let QPath::Resolved(_, ref path) = **path {
1401 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
1405 if let Some(path) = path {
1406 let arg_index = path.segments.iter()
1407 .filter_map(|seg| seg.args.as_ref())
1408 .map(|generic_args| generic_args.args.as_ref())
1411 .filter(|arg| arg.is_const())
1413 .filter(|(_, arg)| arg.id() == hir_id)
1414 .map(|(index, _)| index)
1421 bug!("no arg matching AnonConst in path")
1425 // We've encountered an `AnonConst` in some path, so we need to
1426 // figure out which generic parameter it corresponds to and return
1427 // the relevant type.
1428 let generics = match path.res {
1429 Res::Def(DefKind::Ctor(..), def_id) => {
1430 tcx.generics_of(tcx.parent(def_id).unwrap())
1432 Res::Def(_, def_id) => tcx.generics_of(def_id),
1433 Res::Err => return Some(tcx.types.err),
1434 _ if !fail => return None,
1436 tcx.sess.delay_span_bug(
1439 "unexpected const parent path def {:?}",
1443 return Some(tcx.types.err);
1447 generics.params.iter()
1449 if let ty::GenericParamDefKind::Const = param.kind {
1456 .map(|param| tcx.type_of(param.def_id))
1457 // This is no generic parameter associated with the arg. This is
1458 // probably from an extra arg where one is not needed.
1459 .unwrap_or(tcx.types.err)
1464 tcx.sess.delay_span_bug(
1467 "unexpected const parent path {:?}",
1471 return Some(tcx.types.err);
1479 tcx.sess.delay_span_bug(
1482 "unexpected const parent in type_of_def_id(): {:?}", x
1490 Node::GenericParam(param) => match ¶m.kind {
1491 hir::GenericParamKind::Type { default: Some(ref ty), .. } |
1492 hir::GenericParamKind::Const { ref ty, .. } => {
1499 bug!("unexpected non-type Node::GenericParam: {:?}", x)
1507 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1512 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1513 use rustc::hir::{ImplItem, Item, TraitItem};
1515 debug!("find_opaque_ty_constraints({:?})", def_id);
1517 struct ConstraintLocator<'tcx> {
1520 // (first found type span, actual type, mapping from the opaque type's generic
1521 // parameters to the concrete type's generic parameters)
1523 // The mapping is an index for each use site of a generic parameter in the concrete type
1525 // The indices index into the generic parameters on the opaque type.
1526 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1529 impl ConstraintLocator<'tcx> {
1530 fn check(&mut self, def_id: DefId) {
1531 // Don't try to check items that cannot possibly constrain the type.
1532 if !self.tcx.has_typeck_tables(def_id) {
1534 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1542 .typeck_tables_of(def_id)
1543 .concrete_opaque_types
1545 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1547 "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1553 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1554 let span = self.tcx.def_span(def_id);
1555 // used to quickly look up the position of a generic parameter
1556 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1557 // Skipping binder is ok, since we only use this to find generic parameters and
1559 for (idx, subst) in substs.iter().enumerate() {
1560 if let UnpackedKind::Type(ty) = subst.unpack() {
1561 if let ty::Param(p) = ty.sty {
1562 if index_map.insert(p, idx).is_some() {
1563 // There was already an entry for `p`, meaning a generic parameter
1565 self.tcx.sess.span_err(
1568 "defining opaque type use restricts opaque \
1569 type by using the generic parameter `{}` twice",
1576 self.tcx.sess.delay_span_bug(
1579 "non-defining opaque ty use in defining scope: {:?}, {:?}",
1580 concrete_type, substs,
1586 // Compute the index within the opaque type for each generic parameter used in
1587 // the concrete type.
1588 let indices = concrete_type
1589 .subst(self.tcx, substs)
1591 .filter_map(|t| match &t.sty {
1592 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1595 let is_param = |ty: Ty<'_>| match ty.sty {
1596 ty::Param(_) => true,
1599 if !substs.types().all(is_param) {
1600 self.tcx.sess.span_err(
1602 "defining opaque type use does not fully define opaque type",
1604 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1605 let mut ty = concrete_type.walk().fuse();
1606 let mut p_ty = prev_ty.walk().fuse();
1607 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.sty, &p.sty) {
1608 // Type parameters are equal to any other type parameter for the purpose of
1609 // concrete type equality, as it is possible to obtain the same type just
1610 // by passing matching parameters to a function.
1611 (ty::Param(_), ty::Param(_)) => true,
1614 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1615 debug!("find_opaque_ty_constraints: span={:?}", span);
1616 // Found different concrete types for the opaque type.
1617 let mut err = self.tcx.sess.struct_span_err(
1619 "concrete type differs from previous defining opaque type use",
1623 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1625 err.span_note(prev_span, "previous use here");
1627 } else if indices != *prev_indices {
1628 // Found "same" concrete types, but the generic parameter order differs.
1629 let mut err = self.tcx.sess.struct_span_err(
1631 "concrete type's generic parameters differ from previous defining use",
1633 use std::fmt::Write;
1634 let mut s = String::new();
1635 write!(s, "expected [").unwrap();
1636 let list = |s: &mut String, indices: &Vec<usize>| {
1637 let mut indices = indices.iter().cloned();
1638 if let Some(first) = indices.next() {
1639 write!(s, "`{}`", substs[first]).unwrap();
1641 write!(s, ", `{}`", substs[i]).unwrap();
1645 list(&mut s, prev_indices);
1646 write!(s, "], got [").unwrap();
1647 list(&mut s, &indices);
1648 write!(s, "]").unwrap();
1649 err.span_label(span, s);
1650 err.span_note(prev_span, "previous use here");
1654 self.found = Some((span, concrete_type, indices));
1658 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
1666 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1667 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1668 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1670 fn visit_item(&mut self, it: &'tcx Item) {
1671 debug!("find_existential_constraints: visiting {:?}", it);
1672 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1673 // The opaque type itself or its children are not within its reveal scope.
1674 if def_id != self.def_id {
1676 intravisit::walk_item(self, it);
1679 fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
1680 debug!("find_existential_constraints: visiting {:?}", it);
1681 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1682 // The opaque type itself or its children are not within its reveal scope.
1683 if def_id != self.def_id {
1685 intravisit::walk_impl_item(self, it);
1688 fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
1689 debug!("find_existential_constraints: visiting {:?}", it);
1690 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1692 intravisit::walk_trait_item(self, it);
1696 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1697 let scope = tcx.hir()
1698 .get_defining_scope(hir_id)
1699 .expect("could not get defining scope");
1700 let mut locator = ConstraintLocator {
1706 debug!("find_opaque_ty_constraints: scope={:?}", scope);
1708 if scope == hir::CRATE_HIR_ID {
1709 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1711 debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
1712 match tcx.hir().get(scope) {
1713 // We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
1714 // This allows our visitor to process the defining item itself, causing
1715 // it to pick up any 'sibling' defining uses.
1717 // For example, this code:
1720 // type Blah = impl Debug;
1721 // let my_closure = || -> Blah { true };
1725 // requires us to explicitly process `foo()` in order
1726 // to notice the defining usage of `Blah`.
1727 Node::Item(ref it) => locator.visit_item(it),
1728 Node::ImplItem(ref it) => locator.visit_impl_item(it),
1729 Node::TraitItem(ref it) => locator.visit_trait_item(it),
1731 "{:?} is not a valid scope for an opaque type item",
1737 match locator.found {
1738 Some((_, ty, _)) => ty,
1740 let span = tcx.def_span(def_id);
1741 tcx.sess.span_err(span, "could not find defining uses");
1747 pub fn get_infer_ret_ty(output: &'_ hir::FunctionRetTy) -> Option<&hir::Ty> {
1748 if let hir::FunctionRetTy::Return(ref ty) = output {
1749 if let hir::TyKind::Infer = ty.node {
1756 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1758 use rustc::hir::Node::*;
1760 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1762 let icx = ItemCtxt::new(tcx, def_id);
1764 match tcx.hir().get(hir_id) {
1765 TraitItem(hir::TraitItem {
1766 node: TraitItemKind::Method(MethodSig { header, decl }, TraitMethod::Provided(_)),
1769 | ImplItem(hir::ImplItem {
1770 node: ImplItemKind::Method(MethodSig { header, decl }, _),
1774 node: ItemKind::Fn(decl, header, _, _),
1776 }) => match get_infer_ret_ty(&decl.output) {
1778 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1779 let mut diag = bad_placeholder_type(tcx, ty.span);
1780 let ret_ty = fn_sig.output();
1781 if ret_ty != tcx.types.err {
1782 diag.span_suggestion(
1784 "replace `_` with the correct return type",
1786 Applicability::MaybeIncorrect,
1790 ty::Binder::bind(fn_sig)
1792 None => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl)
1795 TraitItem(hir::TraitItem {
1796 node: TraitItemKind::Method(MethodSig { header, decl }, _),
1799 AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl)
1802 ForeignItem(&hir::ForeignItem {
1803 node: ForeignItemKind::Fn(ref fn_decl, _, _),
1806 let abi = tcx.hir().get_foreign_abi(hir_id);
1807 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1810 Ctor(data) | Variant(
1811 hir::Variant { data, .. }
1812 ) if data.ctor_hir_id().is_some() => {
1813 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1814 let inputs = data.fields()
1816 .map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1817 ty::Binder::bind(tcx.mk_fn_sig(
1821 hir::Unsafety::Normal,
1827 node: hir::ExprKind::Closure(..),
1830 // Closure signatures are not like other function
1831 // signatures and cannot be accessed through `fn_sig`. For
1832 // example, a closure signature excludes the `self`
1833 // argument. In any case they are embedded within the
1834 // closure type as part of the `ClosureSubsts`.
1837 // the signature of a closure, you should use the
1838 // `closure_sig` method on the `ClosureSubsts`:
1840 // closure_substs.closure_sig(def_id, tcx)
1842 // or, inside of an inference context, you can use
1844 // infcx.closure_sig(def_id, closure_substs)
1845 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1849 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1854 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1855 let icx = ItemCtxt::new(tcx, def_id);
1857 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1858 match tcx.hir().expect_item(hir_id).node {
1859 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1860 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1861 let selfty = tcx.type_of(def_id);
1862 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1869 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1870 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1871 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1872 let item = tcx.hir().expect_item(hir_id);
1874 hir::ItemKind::Impl(_, hir::ImplPolarity::Negative, ..) => {
1875 if is_rustc_reservation {
1876 tcx.sess.span_err(item.span, "reservation impls can't be negative");
1878 ty::ImplPolarity::Negative
1880 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, None, _, _) => {
1881 if is_rustc_reservation {
1882 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1884 ty::ImplPolarity::Positive
1886 hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, Some(_tr), _, _) => {
1887 if is_rustc_reservation {
1888 ty::ImplPolarity::Reservation
1890 ty::ImplPolarity::Positive
1893 ref item => bug!("impl_polarity: {:?} not an impl", item),
1897 /// Returns the early-bound lifetimes declared in this generics
1898 /// listing. For anything other than fns/methods, this is just all
1899 /// the lifetimes that are declared. For fns or methods, we have to
1900 /// screen out those that do not appear in any where-clauses etc using
1901 /// `resolve_lifetime::early_bound_lifetimes`.
1902 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1904 generics: &'a hir::Generics,
1905 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {
1909 .filter(move |param| match param.kind {
1910 GenericParamKind::Lifetime { .. } => {
1911 !tcx.is_late_bound(param.hir_id)
1917 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1918 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1919 /// inferred constraints concerning which regions outlive other regions.
1920 fn predicates_defined_on(
1923 ) -> &ty::GenericPredicates<'_> {
1924 debug!("predicates_defined_on({:?})", def_id);
1925 let mut result = tcx.explicit_predicates_of(def_id);
1927 "predicates_defined_on: explicit_predicates_of({:?}) = {:?}",
1931 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1932 if !inferred_outlives.is_empty() {
1933 let span = tcx.def_span(def_id);
1935 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1939 let mut predicates = (*result).clone();
1940 predicates.predicates.extend(inferred_outlives.iter().map(|&p| (p, span)));
1941 result = tcx.arena.alloc(predicates);
1943 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1947 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1948 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1949 /// `Self: Trait` predicates for traits.
1950 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::GenericPredicates<'_> {
1951 let mut result = tcx.predicates_defined_on(def_id);
1953 if tcx.is_trait(def_id) {
1954 // For traits, add `Self: Trait` predicate. This is
1955 // not part of the predicates that a user writes, but it
1956 // is something that one must prove in order to invoke a
1957 // method or project an associated type.
1959 // In the chalk setup, this predicate is not part of the
1960 // "predicates" for a trait item. But it is useful in
1961 // rustc because if you directly (e.g.) invoke a trait
1962 // method like `Trait::method(...)`, you must naturally
1963 // prove that the trait applies to the types that were
1964 // used, and adding the predicate into this list ensures
1965 // that this is done.
1966 let span = tcx.def_span(def_id);
1967 let mut predicates = (*result).clone();
1968 predicates.predicates.push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span));
1969 result = tcx.arena.alloc(predicates);
1971 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1975 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1976 /// N.B., this does not include any implied/inferred constraints.
1977 fn explicit_predicates_of(
1980 ) -> &ty::GenericPredicates<'_> {
1982 use rustc_data_structures::fx::FxHashSet;
1984 debug!("explicit_predicates_of(def_id={:?})", def_id);
1986 /// A data structure with unique elements, which preserves order of insertion.
1987 /// Preserving the order of insertion is important here so as not to break
1988 /// compile-fail UI tests.
1989 struct UniquePredicates<'tcx> {
1990 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1991 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1994 impl<'tcx> UniquePredicates<'tcx> {
1998 uniques: FxHashSet::default(),
2002 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
2003 if self.uniques.insert(value) {
2004 self.predicates.push(value);
2008 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
2015 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
2016 Some(hir_id) => hir_id,
2017 None => return tcx.predicates_of(def_id),
2019 let node = tcx.hir().get(hir_id);
2021 let mut is_trait = None;
2022 let mut is_default_impl_trait = None;
2024 let icx = ItemCtxt::new(tcx, def_id);
2026 const NO_GENERICS: &hir::Generics = &hir::Generics::empty();
2028 let empty_trait_items = HirVec::new();
2030 let mut predicates = UniquePredicates::new();
2032 let ast_generics = match node {
2033 Node::TraitItem(item) => &item.generics,
2035 Node::ImplItem(item) => match item.node {
2036 ImplItemKind::OpaqueTy(ref bounds) => {
2037 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2038 let opaque_ty = tcx.mk_opaque(def_id, substs);
2040 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2041 let bounds = AstConv::compute_bounds(
2045 SizedByDefault::Yes,
2046 tcx.def_span(def_id),
2049 predicates.extend(bounds.predicates(tcx, opaque_ty));
2052 _ => &item.generics,
2055 Node::Item(item) => {
2057 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
2058 if defaultness.is_default() {
2059 is_default_impl_trait = tcx.impl_trait_ref(def_id);
2063 ItemKind::Fn(.., ref generics, _)
2064 | ItemKind::TyAlias(_, ref generics)
2065 | ItemKind::Enum(_, ref generics)
2066 | ItemKind::Struct(_, ref generics)
2067 | ItemKind::Union(_, ref generics) => generics,
2069 ItemKind::Trait(_, _, ref generics, .., ref items) => {
2070 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
2073 ItemKind::TraitAlias(ref generics, _) => {
2074 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &empty_trait_items));
2077 ItemKind::OpaqueTy(OpaqueTy {
2083 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2084 let opaque_ty = tcx.mk_opaque(def_id, substs);
2086 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2087 let bounds = AstConv::compute_bounds(
2091 SizedByDefault::Yes,
2092 tcx.def_span(def_id),
2095 let bounds_predicates = bounds.predicates(tcx, opaque_ty);
2096 if impl_trait_fn.is_some() {
2098 return tcx.arena.alloc(ty::GenericPredicates {
2100 predicates: bounds_predicates,
2103 // named opaque types
2104 predicates.extend(bounds_predicates);
2113 Node::ForeignItem(item) => match item.node {
2114 ForeignItemKind::Static(..) => NO_GENERICS,
2115 ForeignItemKind::Fn(_, _, ref generics) => generics,
2116 ForeignItemKind::Type => NO_GENERICS,
2122 let generics = tcx.generics_of(def_id);
2123 let parent_count = generics.parent_count as u32;
2124 let has_own_self = generics.has_self && parent_count == 0;
2126 // Below we'll consider the bounds on the type parameters (including `Self`)
2127 // and the explicit where-clauses, but to get the full set of predicates
2128 // on a trait we need to add in the supertrait bounds and bounds found on
2129 // associated types.
2130 if let Some((_trait_ref, _)) = is_trait {
2131 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2134 // In default impls, we can assume that the self type implements
2135 // the trait. So in:
2137 // default impl Foo for Bar { .. }
2139 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2140 // (see below). Recall that a default impl is not itself an impl, but rather a
2141 // set of defaults that can be incorporated into another impl.
2142 if let Some(trait_ref) = is_default_impl_trait {
2143 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2146 // Collect the region predicates that were declared inline as
2147 // well. In the case of parameters declared on a fn or method, we
2148 // have to be careful to only iterate over early-bound regions.
2149 let mut index = parent_count + has_own_self as u32;
2150 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2151 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2152 def_id: tcx.hir().local_def_id(param.hir_id),
2154 name: param.name.ident().as_interned_str(),
2159 GenericParamKind::Lifetime { .. } => {
2160 param.bounds.iter().for_each(|bound| match bound {
2161 hir::GenericBound::Outlives(lt) => {
2162 let bound = AstConv::ast_region_to_region(&icx, <, None);
2163 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2164 predicates.push((outlives.to_predicate(), lt.span));
2173 // Collect the predicates that were written inline by the user on each
2174 // type parameter (e.g., `<T: Foo>`).
2175 for param in &ast_generics.params {
2176 if let GenericParamKind::Type { .. } = param.kind {
2177 let name = param.name.ident().as_interned_str();
2178 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2181 let sized = SizedByDefault::Yes;
2182 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2183 predicates.extend(bounds.predicates(tcx, param_ty));
2187 // Add in the bounds that appear in the where-clause.
2188 let where_clause = &ast_generics.where_clause;
2189 for predicate in &where_clause.predicates {
2191 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2192 let ty = icx.to_ty(&bound_pred.bounded_ty);
2194 // Keep the type around in a dummy predicate, in case of no bounds.
2195 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2196 // is still checked for WF.
2197 if bound_pred.bounds.is_empty() {
2198 if let ty::Param(_) = ty.sty {
2199 // This is a `where T:`, which can be in the HIR from the
2200 // transformation that moves `?Sized` to `T`'s declaration.
2201 // We can skip the predicate because type parameters are
2202 // trivially WF, but also we *should*, to avoid exposing
2203 // users who never wrote `where Type:,` themselves, to
2204 // compiler/tooling bugs from not handling WF predicates.
2206 let span = bound_pred.bounded_ty.span;
2207 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2209 (ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
2214 for bound in bound_pred.bounds.iter() {
2216 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2217 let mut bounds = Bounds::default();
2218 let _ = AstConv::instantiate_poly_trait_ref(
2224 predicates.extend(bounds.predicates(tcx, ty));
2227 &hir::GenericBound::Outlives(ref lifetime) => {
2228 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2229 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2230 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2236 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2237 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2238 predicates.extend(region_pred.bounds.iter().map(|bound| {
2239 let (r2, span) = match bound {
2240 hir::GenericBound::Outlives(lt) => {
2241 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2245 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2247 (ty::Predicate::RegionOutlives(pred), span)
2251 &hir::WherePredicate::EqPredicate(..) => {
2257 // Add predicates from associated type bounds.
2258 if let Some((self_trait_ref, trait_items)) = is_trait {
2259 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2260 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2261 let bounds = match trait_item.node {
2262 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2263 _ => return Vec::new().into_iter()
2267 tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id),
2268 self_trait_ref.substs);
2270 let bounds = AstConv::compute_bounds(
2271 &ItemCtxt::new(tcx, def_id),
2274 SizedByDefault::Yes,
2278 bounds.predicates(tcx, assoc_ty).into_iter()
2282 let mut predicates = predicates.predicates;
2284 // Subtle: before we store the predicates into the tcx, we
2285 // sort them so that predicates like `T: Foo<Item=U>` come
2286 // before uses of `U`. This avoids false ambiguity errors
2287 // in trait checking. See `setup_constraining_predicates`
2289 if let Node::Item(&Item {
2290 node: ItemKind::Impl(..),
2294 let self_ty = tcx.type_of(def_id);
2295 let trait_ref = tcx.impl_trait_ref(def_id);
2296 cgp::setup_constraining_predicates(
2300 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2304 let result = tcx.arena.alloc(ty::GenericPredicates {
2305 parent: generics.parent,
2308 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2312 /// Converts a specific `GenericBound` from the AST into a set of
2313 /// predicates that apply to the self type. A vector is returned
2314 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2315 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2316 /// and `<T as Bar>::X == i32`).
2317 fn predicates_from_bound<'tcx>(
2318 astconv: &dyn AstConv<'tcx>,
2320 bound: &'tcx hir::GenericBound,
2321 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2323 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2324 let mut bounds = Bounds::default();
2325 let _ = astconv.instantiate_poly_trait_ref(
2330 bounds.predicates(astconv.tcx(), param_ty)
2332 hir::GenericBound::Outlives(ref lifetime) => {
2333 let region = astconv.ast_region_to_region(lifetime, None);
2334 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2335 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2337 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2341 fn compute_sig_of_foreign_fn_decl<'tcx>(
2344 decl: &'tcx hir::FnDecl,
2346 ) -> ty::PolyFnSig<'tcx> {
2347 let unsafety = if abi == abi::Abi::RustIntrinsic {
2348 intrisic_operation_unsafety(&*tcx.item_name(def_id).as_str())
2350 hir::Unsafety::Unsafe
2352 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2354 // Feature gate SIMD types in FFI, since I am not sure that the
2355 // ABIs are handled at all correctly. -huonw
2356 if abi != abi::Abi::RustIntrinsic
2357 && abi != abi::Abi::PlatformIntrinsic
2358 && !tcx.features().simd_ffi
2360 let check = |ast_ty: &hir::Ty, ty: Ty<'_>| {
2366 "use of SIMD type `{}` in FFI is highly experimental and \
2367 may result in invalid code",
2368 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2371 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2375 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2378 if let hir::Return(ref ty) = decl.output {
2379 check(&ty, *fty.output().skip_binder())
2386 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2387 match tcx.hir().get_if_local(def_id) {
2388 Some(Node::ForeignItem(..)) => true,
2390 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2394 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2395 match tcx.hir().get_if_local(def_id) {
2396 Some(Node::Item(&hir::Item {
2397 node: hir::ItemKind::Static(_, mutbl, _), ..
2399 Some(Node::ForeignItem( &hir::ForeignItem {
2400 node: hir::ForeignItemKind::Static(_, mutbl), ..
2403 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2407 fn from_target_feature(
2410 attr: &ast::Attribute,
2411 whitelist: &FxHashMap<String, Option<Symbol>>,
2412 target_features: &mut Vec<Symbol>,
2414 let list = match attr.meta_item_list() {
2418 let bad_item = |span| {
2419 let msg = "malformed `target_feature` attribute input";
2420 let code = "enable = \"..\"".to_owned();
2421 tcx.sess.struct_span_err(span, &msg)
2422 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2425 let rust_features = tcx.features();
2427 // Only `enable = ...` is accepted in the meta-item list.
2428 if !item.check_name(sym::enable) {
2429 bad_item(item.span());
2433 // Must be of the form `enable = "..."` (a string).
2434 let value = match item.value_str() {
2435 Some(value) => value,
2437 bad_item(item.span());
2442 // We allow comma separation to enable multiple features.
2443 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2444 // Only allow whitelisted features per platform.
2445 let feature_gate = match whitelist.get(feature) {
2449 "the feature named `{}` is not valid for this target",
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::emit_feature_err(
2490 &tcx.sess.parse_sess,
2491 feature_gate.unwrap(),
2493 feature_gate::GateIssue::Language,
2494 &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")
2531 .fatal(&format!("invalid linkage specified: {}", name))
2537 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2538 let attrs = tcx.get_attrs(id);
2540 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2542 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2544 let mut inline_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"
2564 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2565 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2566 } else if attr.check_name(sym::naked) {
2567 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2568 } else if attr.check_name(sym::no_mangle) {
2569 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2570 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2571 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2572 } else if attr.check_name(sym::no_debug) {
2573 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2574 } else if attr.check_name(sym::used) {
2575 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2576 } else if attr.check_name(sym::thread_local) {
2577 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2578 } else if attr.check_name(sym::export_name) {
2579 if let Some(s) = attr.value_str() {
2580 if s.as_str().contains("\0") {
2581 // `#[export_name = ...]` will be converted to a null-terminated string,
2582 // so it may not contain any null characters.
2587 "`export_name` may not contain null characters"
2590 codegen_fn_attrs.export_name = Some(s);
2592 } else if attr.check_name(sym::target_feature) {
2593 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2594 let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
2595 tcx.sess.struct_span_err(attr.span, msg)
2596 .span_label(attr.span, "can only be applied to `unsafe` functions")
2597 .span_label(tcx.def_span(id), "not an `unsafe` function")
2600 from_target_feature(
2605 &mut codegen_fn_attrs.target_features,
2607 } else if attr.check_name(sym::linkage) {
2608 if let Some(val) = attr.value_str() {
2609 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2611 } else if attr.check_name(sym::link_section) {
2612 if let Some(val) = attr.value_str() {
2613 if val.as_str().bytes().any(|b| b == 0) {
2615 "illegal null byte in link_section \
2619 tcx.sess.span_err(attr.span, &msg);
2621 codegen_fn_attrs.link_section = Some(val);
2624 } else if attr.check_name(sym::link_name) {
2625 codegen_fn_attrs.link_name = attr.value_str();
2629 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2630 if attr.path != sym::inline {
2633 match attr.meta().map(|i| i.node) {
2634 Some(MetaItemKind::Word) => {
2638 Some(MetaItemKind::List(ref items)) => {
2640 inline_span = Some(attr.span);
2641 if items.len() != 1 {
2643 tcx.sess.diagnostic(),
2646 "expected one argument"
2649 } else if list_contains_name(&items[..], sym::always) {
2651 } else if list_contains_name(&items[..], sym::never) {
2655 tcx.sess.diagnostic(),
2664 Some(MetaItemKind::NameValue(_)) => ia,
2669 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2670 if attr.path != sym::optimize {
2673 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2674 match attr.meta().map(|i| i.node) {
2675 Some(MetaItemKind::Word) => {
2676 err(attr.span, "expected one argument");
2679 Some(MetaItemKind::List(ref items)) => {
2681 inline_span = Some(attr.span);
2682 if items.len() != 1 {
2683 err(attr.span, "expected one argument");
2685 } else if list_contains_name(&items[..], sym::size) {
2687 } else if list_contains_name(&items[..], sym::speed) {
2690 err(items[0].span(), "invalid argument");
2694 Some(MetaItemKind::NameValue(_)) => ia,
2699 // If a function uses #[target_feature] it can't be inlined into general
2700 // purpose functions as they wouldn't have the right target features
2701 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2703 if codegen_fn_attrs.target_features.len() > 0 {
2704 if codegen_fn_attrs.inline == InlineAttr::Always {
2705 if let Some(span) = inline_span {
2708 "cannot use `#[inline(always)]` with \
2709 `#[target_feature]`",
2715 // Weak lang items have the same semantics as "std internal" symbols in the
2716 // sense that they're preserved through all our LTO passes and only
2717 // strippable by the linker.
2719 // Additionally weak lang items have predetermined symbol names.
2720 if tcx.is_weak_lang_item(id) {
2721 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2723 if let Some(name) = weak_lang_items::link_name(&attrs) {
2724 codegen_fn_attrs.export_name = Some(name);
2725 codegen_fn_attrs.link_name = Some(name);
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;