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 *interprocedural* 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};
18 use crate::constrained_generic_params as cgp;
19 use crate::check::intrinsic::intrisic_operation_unsafety;
21 use crate::middle::lang_items::SizedTraitLangItem;
22 use crate::middle::resolve_lifetime as rl;
23 use crate::middle::weak_lang_items;
24 use rustc::mir::mono::Linkage;
25 use rustc::ty::query::Providers;
26 use rustc::ty::subst::{Subst, InternalSubsts};
27 use rustc::ty::util::Discr;
28 use rustc::ty::util::IntTypeExt;
29 use rustc::ty::subst::UnpackedKind;
30 use rustc::ty::{self, AdtKind, DefIdTree, ToPolyTraitRef, Ty, TyCtxt};
31 use rustc::ty::{ReprOptions, ToPredicate};
32 use rustc::util::captures::Captures;
33 use rustc::util::nodemap::FxHashMap;
34 use rustc_target::spec::abi;
37 use syntax::ast::{Ident, MetaItemKind};
38 use syntax::attr::{InlineAttr, OptimizeAttr, list_contains_name, mark_used};
39 use syntax::source_map::Spanned;
40 use syntax::feature_gate;
41 use syntax::symbol::{InternedString, kw, Symbol, sym};
42 use syntax_pos::{Span, DUMMY_SP};
44 use rustc::hir::def::{CtorKind, Res, DefKind};
46 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
47 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
48 use rustc::hir::GenericParamKind;
49 use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
51 use errors::Applicability;
55 struct OnlySelfBounds(bool);
57 ///////////////////////////////////////////////////////////////////////////
60 fn collect_mod_item_types<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
61 tcx.hir().visit_item_likes_in_module(
63 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor()
67 pub fn provide(providers: &mut Providers<'_>) {
68 *providers = Providers {
72 predicates_defined_on,
73 explicit_predicates_of,
75 type_param_predicates,
84 collect_mod_item_types,
89 ///////////////////////////////////////////////////////////////////////////
91 /// Context specific to some particular item. This is what implements
92 /// `AstConv`. It has information about the predicates that are defined
93 /// on the trait. Unfortunately, this predicate information is
94 /// available in various different forms at various points in the
95 /// process. So we can't just store a pointer to e.g., the AST or the
96 /// parsed ty form, we have to be more flexible. To this end, the
97 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
98 /// `get_type_parameter_bounds` requests, drawing the information from
99 /// the AST (`hir::Generics`), recursively.
100 pub struct ItemCtxt<'a, 'tcx: 'a> {
101 tcx: TyCtxt<'a, 'tcx, 'tcx>,
105 ///////////////////////////////////////////////////////////////////////////
107 struct CollectItemTypesVisitor<'a, 'tcx: 'a> {
108 tcx: TyCtxt<'a, 'tcx, 'tcx>,
111 impl<'a, 'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'a, 'tcx> {
112 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
113 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
116 fn visit_item(&mut self, item: &'tcx hir::Item) {
117 convert_item(self.tcx, item.hir_id);
118 intravisit::walk_item(self, item);
121 fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
122 for param in &generics.params {
124 hir::GenericParamKind::Lifetime { .. } => {}
125 hir::GenericParamKind::Type {
128 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
129 self.tcx.type_of(def_id);
131 hir::GenericParamKind::Type { .. } => {}
132 hir::GenericParamKind::Const { .. } => {
133 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
134 self.tcx.type_of(def_id);
138 intravisit::walk_generics(self, generics);
141 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
142 if let hir::ExprKind::Closure(..) = expr.node {
143 let def_id = self.tcx.hir().local_def_id_from_hir_id(expr.hir_id);
144 self.tcx.generics_of(def_id);
145 self.tcx.type_of(def_id);
147 intravisit::walk_expr(self, expr);
150 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
151 convert_trait_item(self.tcx, trait_item.hir_id);
152 intravisit::walk_trait_item(self, trait_item);
155 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
156 convert_impl_item(self.tcx, impl_item.hir_id);
157 intravisit::walk_impl_item(self, impl_item);
161 ///////////////////////////////////////////////////////////////////////////
162 // Utility types and common code for the above passes.
164 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
165 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_def_id: DefId) -> ItemCtxt<'a, 'tcx> {
166 ItemCtxt { tcx, item_def_id }
170 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
171 pub fn to_ty(&self, ast_ty: &hir::Ty) -> Ty<'tcx> {
172 AstConv::ast_ty_to_ty(self, ast_ty)
176 impl<'a, 'tcx> AstConv<'tcx, 'tcx> for ItemCtxt<'a, 'tcx> {
177 fn tcx<'b>(&'b self) -> TyCtxt<'b, 'tcx, 'tcx> {
181 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId)
182 -> &'tcx ty::GenericPredicates<'tcx> {
185 .type_param_predicates((self.item_def_id, def_id))
191 _def: Option<&ty::GenericParamDef>,
192 ) -> Option<ty::Region<'tcx>> {
196 fn ty_infer(&self, span: Span) -> Ty<'tcx> {
201 "the type placeholder `_` is not allowed within types on item signatures"
202 ).span_label(span, "not allowed in type signatures")
208 fn projected_ty_from_poly_trait_ref(
212 poly_trait_ref: ty::PolyTraitRef<'tcx>,
214 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
215 self.tcx().mk_projection(item_def_id, trait_ref.substs)
217 // no late-bound regions, we can just ignore the binder
222 "cannot extract an associated type from a higher-ranked trait bound \
229 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
230 // types in item signatures are not normalized, to avoid undue
235 fn set_tainted_by_errors(&self) {
236 // no obvious place to track this, just let it go
239 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
240 // no place to record types from signatures?
244 fn type_param_predicates<'a, 'tcx>(
245 tcx: TyCtxt<'a, 'tcx, 'tcx>,
246 (item_def_id, def_id): (DefId, DefId),
247 ) -> &'tcx ty::GenericPredicates<'tcx> {
250 // In the AST, bounds can derive from two places. Either
251 // written inline like `<T : Foo>` or in a where clause like
254 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
255 let param_owner = tcx.hir().ty_param_owner(param_id);
256 let param_owner_def_id = tcx.hir().local_def_id_from_hir_id(param_owner);
257 let generics = tcx.generics_of(param_owner_def_id);
258 let index = generics.param_def_id_to_index[&def_id];
259 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id).as_interned_str());
261 // Don't look for bounds where the type parameter isn't in scope.
262 let parent = if item_def_id == param_owner_def_id {
265 tcx.generics_of(item_def_id).parent
268 let result = parent.map_or(&tcx.common.empty_predicates, |parent| {
269 let icx = ItemCtxt::new(tcx, parent);
270 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
272 let mut extend = None;
274 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
275 let ast_generics = match tcx.hir().get_by_hir_id(item_hir_id) {
276 Node::TraitItem(item) => &item.generics,
278 Node::ImplItem(item) => &item.generics,
280 Node::Item(item) => {
282 ItemKind::Fn(.., ref generics, _)
283 | ItemKind::Impl(_, _, _, ref generics, ..)
284 | ItemKind::Ty(_, ref generics)
285 | ItemKind::Existential(ExistTy {
290 | ItemKind::Enum(_, ref generics)
291 | ItemKind::Struct(_, ref generics)
292 | ItemKind::Union(_, ref generics) => generics,
293 ItemKind::Trait(_, _, ref generics, ..) => {
294 // Implied `Self: Trait` and supertrait bounds.
295 if param_id == item_hir_id {
296 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
297 extend = Some((identity_trait_ref.to_predicate(), item.span));
305 Node::ForeignItem(item) => match item.node {
306 ForeignItemKind::Fn(_, _, ref generics) => generics,
313 let icx = ItemCtxt::new(tcx, item_def_id);
314 let mut result = (*result).clone();
315 result.predicates.extend(extend.into_iter());
317 .extend(icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty,
318 OnlySelfBounds(true)));
319 tcx.arena.alloc(result)
322 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
323 /// Finds bounds from `hir::Generics`. This requires scanning through the
324 /// AST. We do this to avoid having to convert *all* the bounds, which
325 /// would create artificial cycles. Instead we can only convert the
326 /// bounds for a type parameter `X` if `X::Foo` is used.
327 fn type_parameter_bounds_in_generics(
329 ast_generics: &hir::Generics,
330 param_id: hir::HirId,
332 only_self_bounds: OnlySelfBounds,
333 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
334 let from_ty_params = ast_generics
337 .filter_map(|param| match param.kind {
338 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
341 .flat_map(|bounds| bounds.iter())
342 .flat_map(|b| predicates_from_bound(self, ty, b));
344 let from_where_clauses = ast_generics
348 .filter_map(|wp| match *wp {
349 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
353 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
355 } else if !only_self_bounds.0 {
356 Some(self.to_ty(&bp.bounded_ty))
360 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
362 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
364 from_ty_params.chain(from_where_clauses).collect()
368 /// Tests whether this is the AST for a reference to the type
369 /// parameter with ID `param_id`. We use this so as to avoid running
370 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
371 /// conversion of the type to avoid inducing unnecessary cycles.
372 fn is_param<'a, 'tcx>(
373 tcx: TyCtxt<'a, 'tcx, 'tcx>,
375 param_id: hir::HirId,
377 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.node {
379 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
380 def_id == tcx.hir().local_def_id_from_hir_id(param_id)
389 fn convert_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_id: hir::HirId) {
390 let it = tcx.hir().expect_item_by_hir_id(item_id);
391 debug!("convert: item {} with id {}", it.ident, it.hir_id);
392 let def_id = tcx.hir().local_def_id_from_hir_id(item_id);
394 // These don't define types.
395 hir::ItemKind::ExternCrate(_)
396 | hir::ItemKind::Use(..)
397 | hir::ItemKind::Mod(_)
398 | hir::ItemKind::GlobalAsm(_) => {}
399 hir::ItemKind::ForeignMod(ref foreign_mod) => {
400 for item in &foreign_mod.items {
401 let def_id = tcx.hir().local_def_id_from_hir_id(item.hir_id);
402 tcx.generics_of(def_id);
404 tcx.predicates_of(def_id);
405 if let hir::ForeignItemKind::Fn(..) = item.node {
410 hir::ItemKind::Enum(ref enum_definition, _) => {
411 tcx.generics_of(def_id);
413 tcx.predicates_of(def_id);
414 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
416 hir::ItemKind::Impl(..) => {
417 tcx.generics_of(def_id);
419 tcx.impl_trait_ref(def_id);
420 tcx.predicates_of(def_id);
422 hir::ItemKind::Trait(..) => {
423 tcx.generics_of(def_id);
424 tcx.trait_def(def_id);
425 tcx.at(it.span).super_predicates_of(def_id);
426 tcx.predicates_of(def_id);
428 hir::ItemKind::TraitAlias(..) => {
429 tcx.generics_of(def_id);
430 tcx.at(it.span).super_predicates_of(def_id);
431 tcx.predicates_of(def_id);
433 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
434 tcx.generics_of(def_id);
436 tcx.predicates_of(def_id);
438 for f in struct_def.fields() {
439 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
440 tcx.generics_of(def_id);
442 tcx.predicates_of(def_id);
445 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
446 convert_variant_ctor(tcx, ctor_hir_id);
450 // Desugared from `impl Trait` -> visited by the function's return type
451 hir::ItemKind::Existential(hir::ExistTy {
452 impl_trait_fn: Some(_),
456 hir::ItemKind::Existential(..)
457 | hir::ItemKind::Ty(..)
458 | hir::ItemKind::Static(..)
459 | hir::ItemKind::Const(..)
460 | hir::ItemKind::Fn(..) => {
461 tcx.generics_of(def_id);
463 tcx.predicates_of(def_id);
464 if let hir::ItemKind::Fn(..) = it.node {
471 fn convert_trait_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, trait_item_id: hir::HirId) {
472 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
473 let def_id = tcx.hir().local_def_id_from_hir_id(trait_item.hir_id);
474 tcx.generics_of(def_id);
476 match trait_item.node {
477 hir::TraitItemKind::Const(..)
478 | hir::TraitItemKind::Type(_, Some(_))
479 | hir::TraitItemKind::Method(..) => {
481 if let hir::TraitItemKind::Method(..) = trait_item.node {
486 hir::TraitItemKind::Type(_, None) => {}
489 tcx.predicates_of(def_id);
492 fn convert_impl_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, impl_item_id: hir::HirId) {
493 let def_id = tcx.hir().local_def_id_from_hir_id(impl_item_id);
494 tcx.generics_of(def_id);
496 tcx.predicates_of(def_id);
497 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).node {
502 fn convert_variant_ctor<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ctor_id: hir::HirId) {
503 let def_id = tcx.hir().local_def_id_from_hir_id(ctor_id);
504 tcx.generics_of(def_id);
506 tcx.predicates_of(def_id);
509 fn convert_enum_variant_types<'a, 'tcx>(
510 tcx: TyCtxt<'a, 'tcx, 'tcx>,
512 variants: &[hir::Variant],
514 let def = tcx.adt_def(def_id);
515 let repr_type = def.repr.discr_type();
516 let initial = repr_type.initial_discriminant(tcx);
517 let mut prev_discr = None::<Discr<'tcx>>;
519 // fill the discriminant values and field types
520 for variant in variants {
521 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
523 if let Some(ref e) = variant.node.disr_expr {
524 let expr_did = tcx.hir().local_def_id_from_hir_id(e.hir_id);
525 def.eval_explicit_discr(tcx, expr_did)
526 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
533 "enum discriminant overflowed"
536 format!("overflowed on value after {}", prev_discr.unwrap()),
538 "explicitly set `{} = {}` if that is desired outcome",
539 variant.node.ident, wrapped_discr
543 }.unwrap_or(wrapped_discr),
546 for f in variant.node.data.fields() {
547 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
548 tcx.generics_of(def_id);
550 tcx.predicates_of(def_id);
553 // Convert the ctor, if any. This also registers the variant as
555 if let Some(ctor_hir_id) = variant.node.data.ctor_hir_id() {
556 convert_variant_ctor(tcx, ctor_hir_id);
561 fn convert_variant<'a, 'tcx>(
562 tcx: TyCtxt<'a, 'tcx, 'tcx>,
563 variant_did: Option<DefId>,
564 ctor_did: Option<DefId>,
566 discr: ty::VariantDiscr,
567 def: &hir::VariantData,
568 adt_kind: ty::AdtKind,
570 ) -> ty::VariantDef {
571 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
572 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
577 let fid = tcx.hir().local_def_id_from_hir_id(f.hir_id);
578 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
579 if let Some(prev_span) = dup_span {
584 "field `{}` is already declared",
586 ).span_label(f.span, "field already declared")
587 .span_label(prev_span, format!("`{}` first declared here", f.ident))
590 seen_fields.insert(f.ident.modern(), f.span);
596 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
600 let recovered = match def {
601 hir::VariantData::Struct(_, r) => *r,
611 CtorKind::from_hir(def),
618 fn adt_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::AdtDef {
621 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
622 let item = match tcx.hir().get_by_hir_id(hir_id) {
623 Node::Item(item) => item,
627 let repr = ReprOptions::new(tcx, def_id);
628 let (kind, variants) = match item.node {
629 ItemKind::Enum(ref def, _) => {
630 let mut distance_from_explicit = 0;
631 let variants = def.variants
634 let variant_did = Some(tcx.hir().local_def_id_from_hir_id(v.node.id));
635 let ctor_did = v.node.data.ctor_hir_id()
636 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
638 let discr = if let Some(ref e) = v.node.disr_expr {
639 distance_from_explicit = 0;
640 ty::VariantDiscr::Explicit(tcx.hir().local_def_id_from_hir_id(e.hir_id))
642 ty::VariantDiscr::Relative(distance_from_explicit)
644 distance_from_explicit += 1;
646 convert_variant(tcx, variant_did, ctor_did, v.node.ident, discr,
647 &v.node.data, AdtKind::Enum, def_id)
651 (AdtKind::Enum, variants)
653 ItemKind::Struct(ref def, _) => {
654 let variant_did = None;
655 let ctor_did = def.ctor_hir_id()
656 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
658 let variants = std::iter::once(convert_variant(
659 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
660 AdtKind::Struct, def_id,
663 (AdtKind::Struct, variants)
665 ItemKind::Union(ref def, _) => {
666 let variant_did = None;
667 let ctor_did = def.ctor_hir_id()
668 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
670 let variants = std::iter::once(convert_variant(
671 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
672 AdtKind::Union, def_id,
675 (AdtKind::Union, variants)
679 tcx.alloc_adt_def(def_id, kind, variants, repr)
682 /// Ensures that the super-predicates of the trait with a `DefId`
683 /// of `trait_def_id` are converted and stored. This also ensures that
684 /// the transitive super-predicates are converted.
685 fn super_predicates_of<'a, 'tcx>(
686 tcx: TyCtxt<'a, 'tcx, 'tcx>,
688 ) -> &'tcx ty::GenericPredicates<'tcx> {
689 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
690 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
692 let item = match tcx.hir().get_by_hir_id(trait_hir_id) {
693 Node::Item(item) => item,
694 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
697 let (generics, bounds) = match item.node {
698 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
699 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
700 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
703 let icx = ItemCtxt::new(tcx, trait_def_id);
705 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
706 let self_param_ty = tcx.mk_self_type();
707 let superbounds1 = compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
709 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
711 // Convert any explicit superbounds in the where-clause,
712 // e.g., `trait Foo where Self: Bar`.
713 // In the case of trait aliases, however, we include all bounds in the where-clause,
714 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
715 // as one of its "superpredicates".
716 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
717 let superbounds2 = icx.type_parameter_bounds_in_generics(
718 generics, item.hir_id, self_param_ty, OnlySelfBounds(!is_trait_alias));
720 // Combine the two lists to form the complete set of superbounds:
721 let superbounds: Vec<_> = superbounds1.into_iter().chain(superbounds2).collect();
723 // Now require that immediate supertraits are converted,
724 // which will, in turn, reach indirect supertraits.
725 for &(pred, span) in &superbounds {
726 debug!("superbound: {:?}", pred);
727 if let ty::Predicate::Trait(bound) = pred {
728 tcx.at(span).super_predicates_of(bound.def_id());
732 tcx.arena.alloc(ty::GenericPredicates {
734 predicates: superbounds,
738 fn trait_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::TraitDef {
739 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
740 let item = tcx.hir().expect_item_by_hir_id(hir_id);
742 let (is_auto, unsafety) = match item.node {
743 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
744 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
745 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
748 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
749 if paren_sugar && !tcx.features().unboxed_closures {
750 let mut err = tcx.sess.struct_span_err(
752 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
753 which traits can use parenthetical notation",
757 "add `#![feature(unboxed_closures)]` to \
758 the crate attributes to use it"
763 let is_marker = tcx.has_attr(def_id, sym::marker);
764 let def_path_hash = tcx.def_path_hash(def_id);
765 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
769 fn has_late_bound_regions<'a, 'tcx>(
770 tcx: TyCtxt<'a, 'tcx, 'tcx>,
773 struct LateBoundRegionsDetector<'a, 'tcx: 'a> {
774 tcx: TyCtxt<'a, 'tcx, 'tcx>,
775 outer_index: ty::DebruijnIndex,
776 has_late_bound_regions: Option<Span>,
779 impl<'a, 'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'a, 'tcx> {
780 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
781 NestedVisitorMap::None
784 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
785 if self.has_late_bound_regions.is_some() {
789 hir::TyKind::BareFn(..) => {
790 self.outer_index.shift_in(1);
791 intravisit::walk_ty(self, ty);
792 self.outer_index.shift_out(1);
794 _ => intravisit::walk_ty(self, ty),
798 fn visit_poly_trait_ref(
800 tr: &'tcx hir::PolyTraitRef,
801 m: hir::TraitBoundModifier,
803 if self.has_late_bound_regions.is_some() {
806 self.outer_index.shift_in(1);
807 intravisit::walk_poly_trait_ref(self, tr, m);
808 self.outer_index.shift_out(1);
811 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
812 if self.has_late_bound_regions.is_some() {
816 match self.tcx.named_region(lt.hir_id) {
817 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
818 Some(rl::Region::LateBound(debruijn, _, _))
819 | Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
820 Some(rl::Region::LateBound(..))
821 | Some(rl::Region::LateBoundAnon(..))
822 | Some(rl::Region::Free(..))
824 self.has_late_bound_regions = Some(lt.span);
830 fn has_late_bound_regions<'a, 'tcx>(
831 tcx: TyCtxt<'a, 'tcx, 'tcx>,
832 generics: &'tcx hir::Generics,
833 decl: &'tcx hir::FnDecl,
835 let mut visitor = LateBoundRegionsDetector {
837 outer_index: ty::INNERMOST,
838 has_late_bound_regions: None,
840 for param in &generics.params {
841 if let GenericParamKind::Lifetime { .. } = param.kind {
842 if tcx.is_late_bound(param.hir_id) {
843 return Some(param.span);
847 visitor.visit_fn_decl(decl);
848 visitor.has_late_bound_regions
852 Node::TraitItem(item) => match item.node {
853 hir::TraitItemKind::Method(ref sig, _) => {
854 has_late_bound_regions(tcx, &item.generics, &sig.decl)
858 Node::ImplItem(item) => match item.node {
859 hir::ImplItemKind::Method(ref sig, _) => {
860 has_late_bound_regions(tcx, &item.generics, &sig.decl)
864 Node::ForeignItem(item) => match item.node {
865 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
866 has_late_bound_regions(tcx, generics, fn_decl)
870 Node::Item(item) => match item.node {
871 hir::ItemKind::Fn(ref fn_decl, .., ref generics, _) => {
872 has_late_bound_regions(tcx, generics, fn_decl)
880 fn generics_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::Generics {
883 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
885 let node = tcx.hir().get_by_hir_id(hir_id);
886 let parent_def_id = match node {
887 Node::ImplItem(_) | Node::TraitItem(_) | Node::Variant(_) |
888 Node::Ctor(..) | Node::Field(_) => {
889 let parent_id = tcx.hir().get_parent_item(hir_id);
890 Some(tcx.hir().local_def_id_from_hir_id(parent_id))
892 Node::Expr(&hir::Expr {
893 node: hir::ExprKind::Closure(..),
895 }) => Some(tcx.closure_base_def_id(def_id)),
896 Node::Item(item) => match item.node {
897 ItemKind::Existential(hir::ExistTy { impl_trait_fn, .. }) => impl_trait_fn,
903 let mut opt_self = None;
904 let mut allow_defaults = false;
906 let no_generics = hir::Generics::empty();
907 let ast_generics = match node {
908 Node::TraitItem(item) => &item.generics,
910 Node::ImplItem(item) => &item.generics,
912 Node::Item(item) => {
914 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
918 ItemKind::Ty(_, ref generics)
919 | ItemKind::Enum(_, ref generics)
920 | ItemKind::Struct(_, ref generics)
921 | ItemKind::Existential(hir::ExistTy { ref generics, .. })
922 | ItemKind::Union(_, ref generics) => {
923 allow_defaults = true;
927 ItemKind::Trait(_, _, ref generics, ..)
928 | ItemKind::TraitAlias(ref generics, ..) => {
929 // Add in the self type parameter.
931 // Something of a hack: use the node id for the trait, also as
932 // the node id for the Self type parameter.
933 let param_id = item.hir_id;
935 opt_self = Some(ty::GenericParamDef {
937 name: kw::SelfUpper.as_interned_str(),
938 def_id: tcx.hir().local_def_id_from_hir_id(param_id),
939 pure_wrt_drop: false,
940 kind: ty::GenericParamDefKind::Type {
942 object_lifetime_default: rl::Set1::Empty,
947 allow_defaults = true;
955 Node::ForeignItem(item) => match item.node {
956 ForeignItemKind::Static(..) => &no_generics,
957 ForeignItemKind::Fn(_, _, ref generics) => generics,
958 ForeignItemKind::Type => &no_generics,
964 let has_self = opt_self.is_some();
965 let mut parent_has_self = false;
966 let mut own_start = has_self as u32;
967 let parent_count = parent_def_id.map_or(0, |def_id| {
968 let generics = tcx.generics_of(def_id);
969 assert_eq!(has_self, false);
970 parent_has_self = generics.has_self;
971 own_start = generics.count() as u32;
972 generics.parent_count + generics.params.len()
975 let mut params: Vec<_> = opt_self.into_iter().collect();
977 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
981 .map(|(i, param)| ty::GenericParamDef {
982 name: param.name.ident().as_interned_str(),
983 index: own_start + i as u32,
984 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
985 pure_wrt_drop: param.pure_wrt_drop,
986 kind: ty::GenericParamDefKind::Lifetime,
990 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
992 // Now create the real type parameters.
993 let type_start = own_start - has_self as u32 + params.len() as u32;
999 .filter_map(|param| {
1000 let kind = match param.kind {
1001 GenericParamKind::Type {
1006 if param.name.ident().name == kw::SelfUpper {
1009 "`Self` should not be the name of a regular parameter"
1013 if !allow_defaults && default.is_some() {
1014 if !tcx.features().default_type_parameter_fallback {
1016 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1020 "defaults for type parameters are only allowed in \
1021 `struct`, `enum`, `type`, or `trait` definitions."
1027 ty::GenericParamDefKind::Type {
1028 has_default: default.is_some(),
1029 object_lifetime_default: object_lifetime_defaults
1031 .map_or(rl::Set1::Empty, |o| o[i]),
1035 GenericParamKind::Const { .. } => {
1036 if param.name.ident().name == kw::SelfUpper {
1039 "`Self` should not be the name of a regular parameter",
1043 ty::GenericParamDefKind::Const
1048 let param_def = ty::GenericParamDef {
1049 index: type_start + i as u32,
1050 name: param.name.ident().as_interned_str(),
1051 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
1052 pure_wrt_drop: param.pure_wrt_drop,
1060 // provide junk type parameter defs - the only place that
1061 // cares about anything but the length is instantiation,
1062 // and we don't do that for closures.
1063 if let Node::Expr(&hir::Expr {
1064 node: hir::ExprKind::Closure(.., gen),
1068 let dummy_args = if gen.is_some() {
1069 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1071 &["<closure_kind>", "<closure_signature>"][..]
1078 .map(|(i, &arg)| ty::GenericParamDef {
1079 index: type_start + i as u32,
1080 name: InternedString::intern(arg),
1082 pure_wrt_drop: false,
1083 kind: ty::GenericParamDefKind::Type {
1085 object_lifetime_default: rl::Set1::Empty,
1091 if let Some(upvars) = tcx.upvars(def_id) {
1092 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1093 ty::GenericParamDef {
1094 index: type_start + i,
1095 name: InternedString::intern("<upvar>"),
1097 pure_wrt_drop: false,
1098 kind: ty::GenericParamDefKind::Type {
1100 object_lifetime_default: rl::Set1::Empty,
1108 let param_def_id_to_index = params
1110 .map(|param| (param.def_id, param.index))
1113 tcx.arena.alloc(ty::Generics {
1114 parent: parent_def_id,
1117 param_def_id_to_index,
1118 has_self: has_self || parent_has_self,
1119 has_late_bound_regions: has_late_bound_regions(tcx, node),
1123 fn report_assoc_ty_on_inherent_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, span: Span) {
1128 "associated types are not yet supported in inherent impls (see #8995)"
1132 fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
1133 checked_type_of(tcx, def_id, true).unwrap()
1136 /// Same as [`type_of`] but returns [`Option`] instead of failing.
1138 /// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
1139 /// you'd better just call [`type_of`] directly.
1140 pub fn checked_type_of<'a, 'tcx>(
1141 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1144 ) -> Option<Ty<'tcx>> {
1147 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1148 Some(hir_id) => hir_id,
1153 bug!("invalid node");
1157 let icx = ItemCtxt::new(tcx, def_id);
1159 Some(match tcx.hir().get_by_hir_id(hir_id) {
1160 Node::TraitItem(item) => match item.node {
1161 TraitItemKind::Method(..) => {
1162 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1163 tcx.mk_fn_def(def_id, substs)
1165 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1166 TraitItemKind::Type(_, None) => {
1170 span_bug!(item.span, "associated type missing default");
1174 Node::ImplItem(item) => match item.node {
1175 ImplItemKind::Method(..) => {
1176 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1177 tcx.mk_fn_def(def_id, substs)
1179 ImplItemKind::Const(ref ty, _) => icx.to_ty(ty),
1180 ImplItemKind::Existential(_) => {
1182 .impl_trait_ref(tcx.hir().get_parent_did_by_hir_id(hir_id))
1185 report_assoc_ty_on_inherent_impl(tcx, item.span);
1188 find_existential_constraints(tcx, def_id)
1190 ImplItemKind::Type(ref ty) => {
1192 .impl_trait_ref(tcx.hir().get_parent_did_by_hir_id(hir_id))
1195 report_assoc_ty_on_inherent_impl(tcx, item.span);
1202 Node::Item(item) => {
1204 ItemKind::Static(ref t, ..)
1205 | ItemKind::Const(ref t, _)
1206 | ItemKind::Ty(ref t, _)
1207 | ItemKind::Impl(.., ref t, _) => icx.to_ty(t),
1208 ItemKind::Fn(..) => {
1209 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1210 tcx.mk_fn_def(def_id, substs)
1212 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1213 let def = tcx.adt_def(def_id);
1214 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1215 tcx.mk_adt(def, substs)
1217 ItemKind::Existential(hir::ExistTy {
1218 impl_trait_fn: None,
1220 }) => find_existential_constraints(tcx, def_id),
1221 // existential types desugared from impl Trait
1222 ItemKind::Existential(hir::ExistTy {
1223 impl_trait_fn: Some(owner),
1226 tcx.typeck_tables_of(owner)
1227 .concrete_existential_types
1229 .map(|opaque| opaque.concrete_type)
1230 .unwrap_or_else(|| {
1231 // This can occur if some error in the
1232 // owner fn prevented us from populating
1233 // the `concrete_existential_types` table.
1234 tcx.sess.delay_span_bug(
1237 "owner {:?} has no existential type for {:?} in its tables",
1245 | ItemKind::TraitAlias(..)
1247 | ItemKind::ForeignMod(..)
1248 | ItemKind::GlobalAsm(..)
1249 | ItemKind::ExternCrate(..)
1250 | ItemKind::Use(..) => {
1256 "compute_type_of_item: unexpected item type: {:?}",
1263 Node::ForeignItem(foreign_item) => match foreign_item.node {
1264 ForeignItemKind::Fn(..) => {
1265 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1266 tcx.mk_fn_def(def_id, substs)
1268 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1269 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1272 Node::Ctor(&ref def) | Node::Variant(&Spanned {
1273 node: hir::VariantKind { data: ref def, .. },
1276 VariantData::Unit(..) | VariantData::Struct(..) => {
1277 tcx.type_of(tcx.hir().get_parent_did_by_hir_id(hir_id))
1279 VariantData::Tuple(..) => {
1280 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1281 tcx.mk_fn_def(def_id, substs)
1285 Node::Field(field) => icx.to_ty(&field.ty),
1287 Node::Expr(&hir::Expr {
1288 node: hir::ExprKind::Closure(.., gen),
1292 return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
1295 let substs = ty::ClosureSubsts {
1296 substs: InternalSubsts::identity_for_item(tcx, def_id),
1299 tcx.mk_closure(def_id, substs)
1302 Node::AnonConst(_) => {
1303 let parent_node = tcx.hir().get_by_hir_id(tcx.hir().get_parent_node_by_hir_id(hir_id));
1306 node: hir::TyKind::Array(_, ref constant),
1309 | Node::Ty(&hir::Ty {
1310 node: hir::TyKind::Typeof(ref constant),
1313 | Node::Expr(&hir::Expr {
1314 node: ExprKind::Repeat(_, ref constant),
1316 }) if constant.hir_id == hir_id =>
1321 Node::Variant(&Spanned {
1324 disr_expr: Some(ref e),
1328 }) if e.hir_id == hir_id =>
1330 tcx.adt_def(tcx.hir().get_parent_did_by_hir_id(hir_id))
1336 Node::Ty(&hir::Ty { node: hir::TyKind::Path(_), .. }) |
1337 Node::Expr(&hir::Expr { node: ExprKind::Struct(..), .. }) |
1338 Node::Expr(&hir::Expr { node: ExprKind::Path(_), .. }) => {
1339 let path = match parent_node {
1340 Node::Ty(&hir::Ty { node: hir::TyKind::Path(ref path), .. }) |
1341 Node::Expr(&hir::Expr { node: ExprKind::Path(ref path), .. }) => {
1344 Node::Expr(&hir::Expr { node: ExprKind::Struct(ref path, ..), .. }) => {
1347 _ => unreachable!(),
1351 QPath::Resolved(_, ref path) => {
1352 let arg_index = path.segments.iter()
1353 .filter_map(|seg| seg.args.as_ref())
1354 .map(|generic_args| generic_args.args.as_ref())
1357 .filter(|arg| arg.is_const())
1359 .filter(|(_, arg)| arg.id() == hir_id)
1360 .map(|(index, _)| index)
1367 bug!("no arg matching AnonConst in path")
1371 // We've encountered an `AnonConst` in some path, so we need to
1372 // figure out which generic parameter it corresponds to and return
1373 // the relevant type.
1374 let generics = match path.res {
1375 Res::Def(DefKind::Ctor(..), def_id) =>
1376 tcx.generics_of(tcx.parent(def_id).unwrap()),
1377 Res::Def(_, def_id) =>
1378 tcx.generics_of(def_id),
1380 return Some(tcx.types.err),
1384 tcx.sess.delay_span_bug(
1387 "unexpected const parent path def {:?}", x
1390 return Some(tcx.types.err);
1394 generics.params.iter()
1396 if let ty::GenericParamDefKind::Const = param.kind {
1403 .map(|param| tcx.type_of(param.def_id))
1404 // This is no generic parameter associated with the arg. This is
1405 // probably from an extra arg where one is not needed.
1406 .unwrap_or(tcx.types.err)
1412 tcx.sess.delay_span_bug(
1415 "unexpected const parent path {:?}", x
1427 tcx.sess.delay_span_bug(
1430 "unexpected const parent in type_of_def_id(): {:?}", x
1438 Node::GenericParam(param) => match ¶m.kind {
1439 hir::GenericParamKind::Type { default: Some(ref ty), .. } |
1440 hir::GenericParamKind::Const { ref ty, .. } => {
1447 bug!("unexpected non-type Node::GenericParam: {:?}", x)
1455 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1460 fn find_existential_constraints<'a, 'tcx>(
1461 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1464 use rustc::hir::{ImplItem, Item, TraitItem};
1466 struct ConstraintLocator<'a, 'tcx: 'a> {
1467 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1469 // First found type span, actual type, mapping from the existential type's generic
1470 // parameters to the concrete type's generic parameters
1472 // The mapping is an index for each use site of a generic parameter in the concrete type
1474 // The indices index into the generic parameters on the existential type.
1475 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1478 impl<'a, 'tcx> ConstraintLocator<'a, 'tcx> {
1479 fn check(&mut self, def_id: DefId) {
1480 trace!("checking {:?}", def_id);
1481 // don't try to check items that cannot possibly constrain the type
1482 if !self.tcx.has_typeck_tables(def_id) {
1483 trace!("no typeck tables for {:?}", def_id);
1488 .typeck_tables_of(def_id)
1489 .concrete_existential_types
1491 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1492 // FIXME(oli-obk): trace the actual span from inference to improve errors
1493 let span = self.tcx.def_span(def_id);
1494 // used to quickly look up the position of a generic parameter
1495 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1496 // skip binder is ok, since we only use this to find generic parameters and their
1498 for (idx, subst) in substs.iter().enumerate() {
1499 if let UnpackedKind::Type(ty) = subst.unpack() {
1500 if let ty::Param(p) = ty.sty {
1501 if index_map.insert(p, idx).is_some() {
1502 // there was already an entry for `p`, meaning a generic parameter
1504 self.tcx.sess.span_err(
1506 &format!("defining existential type use restricts existential \
1507 type by using the generic parameter `{}` twice", p.name),
1512 self.tcx.sess.delay_span_bug(
1515 "non-defining exist ty use in defining scope: {:?}, {:?}",
1516 concrete_type, substs,
1522 // compute the index within the existential type for each generic parameter used in
1523 // the concrete type
1524 let indices = concrete_type
1525 .subst(self.tcx, substs)
1527 .filter_map(|t| match &t.sty {
1528 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1531 let is_param = |ty: Ty<'_>| match ty.sty {
1532 ty::Param(_) => true,
1535 if !substs.types().all(is_param) {
1536 self.tcx.sess.span_err(
1538 "defining existential type use does not fully define existential type",
1540 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1541 let mut ty = concrete_type.walk().fuse();
1542 let mut p_ty = prev_ty.walk().fuse();
1543 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.sty, &p.sty) {
1544 // type parameters are equal to any other type parameter for the purpose of
1545 // concrete type equality, as it is possible to obtain the same type just
1546 // by passing matching parameters to a function.
1547 (ty::Param(_), ty::Param(_)) => true,
1550 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1551 // found different concrete types for the existential type
1552 let mut err = self.tcx.sess.struct_span_err(
1554 "concrete type differs from previous defining existential type use",
1558 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1560 err.span_note(prev_span, "previous use here");
1562 } else if indices != *prev_indices {
1563 // found "same" concrete types, but the generic parameter order differs
1564 let mut err = self.tcx.sess.struct_span_err(
1566 "concrete type's generic parameters differ from previous defining use",
1568 use std::fmt::Write;
1569 let mut s = String::new();
1570 write!(s, "expected [").unwrap();
1571 let list = |s: &mut String, indices: &Vec<usize>| {
1572 let mut indices = indices.iter().cloned();
1573 if let Some(first) = indices.next() {
1574 write!(s, "`{}`", substs[first]).unwrap();
1576 write!(s, ", `{}`", substs[i]).unwrap();
1580 list(&mut s, prev_indices);
1581 write!(s, "], got [").unwrap();
1582 list(&mut s, &indices);
1583 write!(s, "]").unwrap();
1584 err.span_label(span, s);
1585 err.span_note(prev_span, "previous use here");
1589 self.found = Some((span, concrete_type, indices));
1595 impl<'a, 'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'a, 'tcx> {
1596 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1597 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1599 fn visit_item(&mut self, it: &'tcx Item) {
1600 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1601 // the existential type itself or its children are not within its reveal scope
1602 if def_id != self.def_id {
1604 intravisit::walk_item(self, it);
1607 fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
1608 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1609 // the existential type itself or its children are not within its reveal scope
1610 if def_id != self.def_id {
1612 intravisit::walk_impl_item(self, it);
1615 fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
1616 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1618 intravisit::walk_trait_item(self, it);
1622 let mut locator = ConstraintLocator {
1627 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1628 let parent = tcx.hir().get_parent_item(hir_id);
1630 trace!("parent_id: {:?}", parent);
1632 if parent == hir::CRATE_HIR_ID {
1633 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1635 trace!("parent: {:?}", tcx.hir().get_by_hir_id(parent));
1636 match tcx.hir().get_by_hir_id(parent) {
1637 Node::Item(ref it) => intravisit::walk_item(&mut locator, it),
1638 Node::ImplItem(ref it) => intravisit::walk_impl_item(&mut locator, it),
1639 Node::TraitItem(ref it) => intravisit::walk_trait_item(&mut locator, it),
1641 "{:?} is not a valid parent of an existential type item",
1647 match locator.found {
1648 Some((_, ty, _)) => ty,
1650 let span = tcx.def_span(def_id);
1651 tcx.sess.span_err(span, "could not find defining uses");
1657 fn fn_sig<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ty::PolyFnSig<'tcx> {
1659 use rustc::hir::Node::*;
1661 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1663 let icx = ItemCtxt::new(tcx, def_id);
1665 match tcx.hir().get_by_hir_id(hir_id) {
1666 TraitItem(hir::TraitItem {
1667 node: TraitItemKind::Method(sig, _),
1670 | ImplItem(hir::ImplItem {
1671 node: ImplItemKind::Method(sig, _),
1673 }) => AstConv::ty_of_fn(&icx, sig.header.unsafety, sig.header.abi, &sig.decl),
1676 node: ItemKind::Fn(decl, header, _, _),
1678 }) => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl),
1680 ForeignItem(&hir::ForeignItem {
1681 node: ForeignItemKind::Fn(ref fn_decl, _, _),
1684 let abi = tcx.hir().get_foreign_abi_by_hir_id(hir_id);
1685 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1688 Ctor(data) | Variant(Spanned {
1689 node: hir::VariantKind { data, .. },
1691 }) if data.ctor_hir_id().is_some() => {
1692 let ty = tcx.type_of(tcx.hir().get_parent_did_by_hir_id(hir_id));
1693 let inputs = data.fields()
1695 .map(|f| tcx.type_of(tcx.hir().local_def_id_from_hir_id(f.hir_id)));
1696 ty::Binder::bind(tcx.mk_fn_sig(
1700 hir::Unsafety::Normal,
1706 node: hir::ExprKind::Closure(..),
1709 // Closure signatures are not like other function
1710 // signatures and cannot be accessed through `fn_sig`. For
1711 // example, a closure signature excludes the `self`
1712 // argument. In any case they are embedded within the
1713 // closure type as part of the `ClosureSubsts`.
1716 // the signature of a closure, you should use the
1717 // `closure_sig` method on the `ClosureSubsts`:
1719 // closure_substs.closure_sig(def_id, tcx)
1721 // or, inside of an inference context, you can use
1723 // infcx.closure_sig(def_id, closure_substs)
1724 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1728 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1733 fn impl_trait_ref<'a, 'tcx>(
1734 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1736 ) -> Option<ty::TraitRef<'tcx>> {
1737 let icx = ItemCtxt::new(tcx, def_id);
1739 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1740 match tcx.hir().expect_item_by_hir_id(hir_id).node {
1741 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1742 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1743 let selfty = tcx.type_of(def_id);
1744 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1751 fn impl_polarity<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> hir::ImplPolarity {
1752 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1753 match tcx.hir().expect_item_by_hir_id(hir_id).node {
1754 hir::ItemKind::Impl(_, polarity, ..) => polarity,
1755 ref item => bug!("impl_polarity: {:?} not an impl", item),
1759 // Is it marked with ?Sized
1760 fn is_unsized<'gcx: 'tcx, 'tcx>(
1761 astconv: &dyn AstConv<'gcx, 'tcx>,
1762 ast_bounds: &[hir::GenericBound],
1765 let tcx = astconv.tcx();
1767 // Try to find an unbound in bounds.
1768 let mut unbound = None;
1769 for ab in ast_bounds {
1770 if let &hir::GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = ab {
1771 if unbound.is_none() {
1772 unbound = Some(ptr.trait_ref.clone());
1778 "type parameter has more than one relaxed default \
1779 bound, only one is supported"
1785 let kind_id = tcx.lang_items().require(SizedTraitLangItem);
1788 // FIXME(#8559) currently requires the unbound to be built-in.
1789 if let Ok(kind_id) = kind_id {
1790 if tpb.path.res != Res::Def(DefKind::Trait, kind_id) {
1793 "default bound relaxed for a type parameter, but \
1794 this does nothing because the given bound is not \
1795 a default. Only `?Sized` is supported",
1800 _ if kind_id.is_ok() => {
1803 // No lang item for Sized, so we can't add it as a bound.
1810 /// Returns the early-bound lifetimes declared in this generics
1811 /// listing. For anything other than fns/methods, this is just all
1812 /// the lifetimes that are declared. For fns or methods, we have to
1813 /// screen out those that do not appear in any where-clauses etc using
1814 /// `resolve_lifetime::early_bound_lifetimes`.
1815 fn early_bound_lifetimes_from_generics<'a, 'tcx>(
1816 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1817 generics: &'a hir::Generics,
1818 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {
1822 .filter(move |param| match param.kind {
1823 GenericParamKind::Lifetime { .. } => {
1824 !tcx.is_late_bound(param.hir_id)
1830 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1831 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1832 /// inferred constraints concerning which regions outlive other regions.
1833 fn predicates_defined_on<'a, 'tcx>(
1834 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1836 ) -> &'tcx ty::GenericPredicates<'tcx> {
1837 debug!("predicates_defined_on({:?})", def_id);
1838 let mut result = tcx.explicit_predicates_of(def_id);
1840 "predicates_defined_on: explicit_predicates_of({:?}) = {:?}",
1844 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1845 if !inferred_outlives.is_empty() {
1846 let span = tcx.def_span(def_id);
1848 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1852 let mut predicates = (*result).clone();
1853 predicates.predicates.extend(inferred_outlives.iter().map(|&p| (p, span)));
1854 result = tcx.arena.alloc(predicates);
1856 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1860 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1861 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1862 /// `Self: Trait` predicates for traits.
1863 fn predicates_of<'a, 'tcx>(
1864 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1866 ) -> &'tcx ty::GenericPredicates<'tcx> {
1867 let mut result = tcx.predicates_defined_on(def_id);
1869 if tcx.is_trait(def_id) {
1870 // For traits, add `Self: Trait` predicate. This is
1871 // not part of the predicates that a user writes, but it
1872 // is something that one must prove in order to invoke a
1873 // method or project an associated type.
1875 // In the chalk setup, this predicate is not part of the
1876 // "predicates" for a trait item. But it is useful in
1877 // rustc because if you directly (e.g.) invoke a trait
1878 // method like `Trait::method(...)`, you must naturally
1879 // prove that the trait applies to the types that were
1880 // used, and adding the predicate into this list ensures
1881 // that this is done.
1882 let span = tcx.def_span(def_id);
1883 let mut predicates = (*result).clone();
1884 predicates.predicates.push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span));
1885 result = tcx.arena.alloc(predicates);
1887 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1891 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1892 /// N.B., this does not include any implied/inferred constraints.
1893 fn explicit_predicates_of<'a, 'tcx>(
1894 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1896 ) -> &'tcx ty::GenericPredicates<'tcx> {
1898 use rustc_data_structures::fx::FxHashSet;
1900 debug!("explicit_predicates_of(def_id={:?})", def_id);
1902 /// A data structure with unique elements, which preserves order of insertion.
1903 /// Preserving the order of insertion is important here so as not to break
1904 /// compile-fail UI tests.
1905 struct UniquePredicates<'tcx> {
1906 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1907 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1910 impl<'tcx> UniquePredicates<'tcx> {
1914 uniques: FxHashSet::default(),
1918 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
1919 if self.uniques.insert(value) {
1920 self.predicates.push(value);
1924 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
1931 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1932 Some(hir_id) => hir_id,
1933 None => return tcx.predicates_of(def_id),
1935 let node = tcx.hir().get_by_hir_id(hir_id);
1937 let mut is_trait = None;
1938 let mut is_default_impl_trait = None;
1940 let icx = ItemCtxt::new(tcx, def_id);
1941 let no_generics = hir::Generics::empty();
1942 let empty_trait_items = HirVec::new();
1944 let mut predicates = UniquePredicates::new();
1946 let ast_generics = match node {
1947 Node::TraitItem(item) => &item.generics,
1949 Node::ImplItem(item) => match item.node {
1950 ImplItemKind::Existential(ref bounds) => {
1951 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1952 let opaque_ty = tcx.mk_opaque(def_id, substs);
1954 // Collect the bounds, i.e., the `A+B+'c` in `impl A+B+'c`.
1955 let bounds = compute_bounds(
1959 SizedByDefault::Yes,
1960 tcx.def_span(def_id),
1963 predicates.extend(bounds.predicates(tcx, opaque_ty));
1966 _ => &item.generics,
1969 Node::Item(item) => {
1971 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
1972 if defaultness.is_default() {
1973 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1977 ItemKind::Fn(.., ref generics, _)
1978 | ItemKind::Ty(_, ref generics)
1979 | ItemKind::Enum(_, ref generics)
1980 | ItemKind::Struct(_, ref generics)
1981 | ItemKind::Union(_, ref generics) => generics,
1983 ItemKind::Trait(_, _, ref generics, .., ref items) => {
1984 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
1987 ItemKind::TraitAlias(ref generics, _) => {
1988 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &empty_trait_items));
1991 ItemKind::Existential(ExistTy {
1997 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1998 let opaque_ty = tcx.mk_opaque(def_id, substs);
2000 // Collect the bounds, i.e., the `A+B+'c` in `impl A+B+'c`.
2001 let bounds = compute_bounds(
2005 SizedByDefault::Yes,
2006 tcx.def_span(def_id),
2009 if impl_trait_fn.is_some() {
2011 return tcx.arena.alloc(ty::GenericPredicates {
2013 predicates: bounds.predicates(tcx, opaque_ty),
2016 // named existential types
2017 predicates.extend(bounds.predicates(tcx, opaque_ty));
2026 Node::ForeignItem(item) => match item.node {
2027 ForeignItemKind::Static(..) => &no_generics,
2028 ForeignItemKind::Fn(_, _, ref generics) => generics,
2029 ForeignItemKind::Type => &no_generics,
2035 let generics = tcx.generics_of(def_id);
2036 let parent_count = generics.parent_count as u32;
2037 let has_own_self = generics.has_self && parent_count == 0;
2039 // Below we'll consider the bounds on the type parameters (including `Self`)
2040 // and the explicit where-clauses, but to get the full set of predicates
2041 // on a trait we need to add in the supertrait bounds and bounds found on
2042 // associated types.
2043 if let Some((_trait_ref, _)) = is_trait {
2044 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2047 // In default impls, we can assume that the self type implements
2048 // the trait. So in:
2050 // default impl Foo for Bar { .. }
2052 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2053 // (see below). Recall that a default impl is not itself an impl, but rather a
2054 // set of defaults that can be incorporated into another impl.
2055 if let Some(trait_ref) = is_default_impl_trait {
2056 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2059 // Collect the region predicates that were declared inline as
2060 // well. In the case of parameters declared on a fn or method, we
2061 // have to be careful to only iterate over early-bound regions.
2062 let mut index = parent_count + has_own_self as u32;
2063 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2064 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2065 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
2067 name: param.name.ident().as_interned_str(),
2072 GenericParamKind::Lifetime { .. } => {
2073 param.bounds.iter().for_each(|bound| match bound {
2074 hir::GenericBound::Outlives(lt) => {
2075 let bound = AstConv::ast_region_to_region(&icx, <, None);
2076 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2077 predicates.push((outlives.to_predicate(), lt.span));
2086 // Collect the predicates that were written inline by the user on each
2087 // type parameter (e.g., `<T:Foo>`).
2088 for param in &ast_generics.params {
2089 if let GenericParamKind::Type { .. } = param.kind {
2090 let name = param.name.ident().as_interned_str();
2091 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2094 let sized = SizedByDefault::Yes;
2095 let bounds = compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2096 predicates.extend(bounds.predicates(tcx, param_ty));
2100 // Add in the bounds that appear in the where-clause
2101 let where_clause = &ast_generics.where_clause;
2102 for predicate in &where_clause.predicates {
2104 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2105 let ty = icx.to_ty(&bound_pred.bounded_ty);
2107 // Keep the type around in a dummy predicate, in case of no bounds.
2108 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2109 // is still checked for WF.
2110 if bound_pred.bounds.is_empty() {
2111 if let ty::Param(_) = ty.sty {
2112 // This is a `where T:`, which can be in the HIR from the
2113 // transformation that moves `?Sized` to `T`'s declaration.
2114 // We can skip the predicate because type parameters are
2115 // trivially WF, but also we *should*, to avoid exposing
2116 // users who never wrote `where Type:,` themselves, to
2117 // compiler/tooling bugs from not handling WF predicates.
2119 let span = bound_pred.bounded_ty.span;
2120 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2122 (ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
2127 for bound in bound_pred.bounds.iter() {
2129 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2130 let mut projections = Vec::new();
2132 let (trait_ref, _) = AstConv::instantiate_poly_trait_ref(
2140 iter::once((trait_ref.to_predicate(), poly_trait_ref.span)).chain(
2141 projections.iter().map(|&(p, span)| (p.to_predicate(), span)
2145 &hir::GenericBound::Outlives(ref lifetime) => {
2146 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2147 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2148 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2154 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2155 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2156 predicates.extend(region_pred.bounds.iter().map(|bound| {
2157 let (r2, span) = match bound {
2158 hir::GenericBound::Outlives(lt) => {
2159 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2163 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2165 (ty::Predicate::RegionOutlives(pred), span)
2169 &hir::WherePredicate::EqPredicate(..) => {
2175 // Add predicates from associated type bounds.
2176 if let Some((self_trait_ref, trait_items)) = is_trait {
2177 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2178 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2179 let bounds = match trait_item.node {
2180 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2181 _ => return vec![].into_iter()
2185 tcx.mk_projection(tcx.hir().local_def_id_from_hir_id(trait_item.hir_id),
2186 self_trait_ref.substs);
2188 let bounds = compute_bounds(
2189 &ItemCtxt::new(tcx, def_id),
2192 SizedByDefault::Yes,
2196 bounds.predicates(tcx, assoc_ty).into_iter()
2200 let mut predicates = predicates.predicates;
2202 // Subtle: before we store the predicates into the tcx, we
2203 // sort them so that predicates like `T: Foo<Item=U>` come
2204 // before uses of `U`. This avoids false ambiguity errors
2205 // in trait checking. See `setup_constraining_predicates`
2207 if let Node::Item(&Item {
2208 node: ItemKind::Impl(..),
2212 let self_ty = tcx.type_of(def_id);
2213 let trait_ref = tcx.impl_trait_ref(def_id);
2214 cgp::setup_constraining_predicates(
2218 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2222 let result = tcx.arena.alloc(ty::GenericPredicates {
2223 parent: generics.parent,
2226 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2230 pub enum SizedByDefault {
2235 /// Translate the AST's notion of ty param bounds (which are an enum consisting of a newtyped `Ty`
2236 /// or a region) to ty's notion of ty param bounds, which can either be user-defined traits, or the
2237 /// built-in trait `Send`.
2238 pub fn compute_bounds<'gcx: 'tcx, 'tcx>(
2239 astconv: &dyn AstConv<'gcx, 'tcx>,
2241 ast_bounds: &[hir::GenericBound],
2242 sized_by_default: SizedByDefault,
2245 let mut region_bounds = Vec::new();
2246 let mut trait_bounds = Vec::new();
2248 for ast_bound in ast_bounds {
2250 hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::None) => trait_bounds.push(b),
2251 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {}
2252 hir::GenericBound::Outlives(ref l) => region_bounds.push(l),
2256 let mut projection_bounds = Vec::new();
2258 let mut trait_bounds: Vec<_> = trait_bounds.iter().map(|&bound| {
2259 let (poly_trait_ref, _) = astconv.instantiate_poly_trait_ref(
2262 &mut projection_bounds,
2264 (poly_trait_ref, bound.span)
2267 let region_bounds = region_bounds
2269 .map(|r| (astconv.ast_region_to_region(r, None), r.span))
2272 trait_bounds.sort_by_key(|(t, _)| t.def_id());
2274 let implicitly_sized = if let SizedByDefault::Yes = sized_by_default {
2275 if !is_unsized(astconv, ast_bounds, span) {
2292 /// Converts a specific `GenericBound` from the AST into a set of
2293 /// predicates that apply to the self type. A vector is returned
2294 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2295 /// predicates) to one (`T: Foo`) to many (`T: Bar<X=i32>` adds `T: Bar`
2296 /// and `<T as Bar>::X == i32`).
2297 fn predicates_from_bound<'tcx>(
2298 astconv: &dyn AstConv<'tcx, 'tcx>,
2300 bound: &hir::GenericBound,
2301 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2303 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2304 let mut projections = Vec::new();
2305 let (pred, _) = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut projections);
2306 iter::once((pred.to_predicate(), tr.span)).chain(
2309 .map(|(p, span)| (p.to_predicate(), span))
2312 hir::GenericBound::Outlives(ref lifetime) => {
2313 let region = astconv.ast_region_to_region(lifetime, None);
2314 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2315 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2317 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2321 fn compute_sig_of_foreign_fn_decl<'a, 'tcx>(
2322 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2326 ) -> ty::PolyFnSig<'tcx> {
2327 let unsafety = if abi == abi::Abi::RustIntrinsic {
2328 intrisic_operation_unsafety(&*tcx.item_name(def_id).as_str())
2330 hir::Unsafety::Unsafe
2332 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2334 // feature gate SIMD types in FFI, since I (huonw) am not sure the
2335 // ABIs are handled at all correctly.
2336 if abi != abi::Abi::RustIntrinsic
2337 && abi != abi::Abi::PlatformIntrinsic
2338 && !tcx.features().simd_ffi
2340 let check = |ast_ty: &hir::Ty, ty: Ty<'_>| {
2346 "use of SIMD type `{}` in FFI is highly experimental and \
2347 may result in invalid code",
2348 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2351 .help("add #![feature(simd_ffi)] to the crate attributes to enable")
2355 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2358 if let hir::Return(ref ty) = decl.output {
2359 check(&ty, *fty.output().skip_binder())
2366 fn is_foreign_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
2367 match tcx.hir().get_if_local(def_id) {
2368 Some(Node::ForeignItem(..)) => true,
2370 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2374 fn static_mutability<'a, 'tcx>(
2375 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2377 ) -> Option<hir::Mutability> {
2378 match tcx.hir().get_if_local(def_id) {
2379 Some(Node::Item(&hir::Item {
2380 node: hir::ItemKind::Static(_, mutbl, _), ..
2382 Some(Node::ForeignItem( &hir::ForeignItem {
2383 node: hir::ForeignItemKind::Static(_, mutbl), ..
2386 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2390 fn from_target_feature(
2391 tcx: TyCtxt<'_, '_, '_>,
2393 attr: &ast::Attribute,
2394 whitelist: &FxHashMap<String, Option<Symbol>>,
2395 target_features: &mut Vec<Symbol>,
2397 let list = match attr.meta_item_list() {
2401 let bad_item = |span| {
2402 let msg = "malformed `target_feature` attribute input";
2403 let code = "enable = \"..\"".to_owned();
2404 tcx.sess.struct_span_err(span, &msg)
2405 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2408 let rust_features = tcx.features();
2410 // Only `enable = ...` is accepted in the meta item list
2411 if !item.check_name(sym::enable) {
2412 bad_item(item.span());
2416 // Must be of the form `enable = "..."` ( a string)
2417 let value = match item.value_str() {
2418 Some(value) => value,
2420 bad_item(item.span());
2425 // We allow comma separation to enable multiple features
2426 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2427 // Only allow whitelisted features per platform
2428 let feature_gate = match whitelist.get(feature) {
2432 "the feature named `{}` is not valid for this target",
2435 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2438 format!("`{}` is not valid for this target", feature),
2440 if feature.starts_with("+") {
2441 let valid = whitelist.contains_key(&feature[1..]);
2443 err.help("consider removing the leading `+` in the feature name");
2451 // Only allow features whose feature gates have been enabled
2452 let allowed = match feature_gate.as_ref().map(|s| *s) {
2453 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2454 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2455 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2456 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2457 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2458 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2459 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2460 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2461 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2462 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2463 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2464 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2465 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2466 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2467 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2468 Some(name) => bug!("unknown target feature gate {}", name),
2471 if !allowed && id.is_local() {
2472 feature_gate::emit_feature_err(
2473 &tcx.sess.parse_sess,
2474 feature_gate.unwrap(),
2476 feature_gate::GateIssue::Language,
2477 &format!("the target feature `{}` is currently unstable", feature),
2480 Some(Symbol::intern(feature))
2485 fn linkage_by_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId, name: &str) -> Linkage {
2486 use rustc::mir::mono::Linkage::*;
2488 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2489 // applicable to variable declarations and may not really make sense for
2490 // Rust code in the first place but whitelist them anyway and trust that
2491 // the user knows what s/he's doing. Who knows, unanticipated use cases
2492 // may pop up in the future.
2494 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2495 // and don't have to be, LLVM treats them as no-ops.
2497 "appending" => Appending,
2498 "available_externally" => AvailableExternally,
2500 "extern_weak" => ExternalWeak,
2501 "external" => External,
2502 "internal" => Internal,
2503 "linkonce" => LinkOnceAny,
2504 "linkonce_odr" => LinkOnceODR,
2505 "private" => Private,
2507 "weak_odr" => WeakODR,
2509 let span = tcx.hir().span_if_local(def_id);
2510 if let Some(span) = span {
2511 tcx.sess.span_fatal(span, "invalid linkage specified")
2514 .fatal(&format!("invalid linkage specified: {}", name))
2520 fn codegen_fn_attrs<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: DefId) -> CodegenFnAttrs {
2521 let attrs = tcx.get_attrs(id);
2523 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2525 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2527 let mut inline_span = None;
2528 for attr in attrs.iter() {
2529 if attr.check_name(sym::cold) {
2530 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2531 } else if attr.check_name(sym::allocator) {
2532 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2533 } else if attr.check_name(sym::unwind) {
2534 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2535 } else if attr.check_name(sym::ffi_returns_twice) {
2536 if tcx.is_foreign_item(id) {
2537 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2539 // `#[ffi_returns_twice]` is only allowed `extern fn`s
2544 "`#[ffi_returns_twice]` may only be used on foreign functions"
2547 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2548 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2549 } else if attr.check_name(sym::naked) {
2550 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2551 } else if attr.check_name(sym::no_mangle) {
2552 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2553 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2554 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2555 } else if attr.check_name(sym::no_debug) {
2556 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2557 } else if attr.check_name(sym::used) {
2558 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2559 } else if attr.check_name(sym::thread_local) {
2560 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2561 } else if attr.check_name(sym::export_name) {
2562 if let Some(s) = attr.value_str() {
2563 if s.as_str().contains("\0") {
2564 // `#[export_name = ...]` will be converted to a null-terminated string,
2565 // so it may not contain any null characters.
2570 "`export_name` may not contain null characters"
2573 codegen_fn_attrs.export_name = Some(s);
2575 } else if attr.check_name(sym::target_feature) {
2576 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2577 let msg = "#[target_feature(..)] can only be applied to `unsafe` functions";
2578 tcx.sess.struct_span_err(attr.span, msg)
2579 .span_label(attr.span, "can only be applied to `unsafe` functions")
2580 .span_label(tcx.def_span(id), "not an `unsafe` function")
2583 from_target_feature(
2588 &mut codegen_fn_attrs.target_features,
2590 } else if attr.check_name(sym::linkage) {
2591 if let Some(val) = attr.value_str() {
2592 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2594 } else if attr.check_name(sym::link_section) {
2595 if let Some(val) = attr.value_str() {
2596 if val.as_str().bytes().any(|b| b == 0) {
2598 "illegal null byte in link_section \
2602 tcx.sess.span_err(attr.span, &msg);
2604 codegen_fn_attrs.link_section = Some(val);
2607 } else if attr.check_name(sym::link_name) {
2608 codegen_fn_attrs.link_name = attr.value_str();
2612 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2613 if attr.path != sym::inline {
2616 match attr.meta().map(|i| i.node) {
2617 Some(MetaItemKind::Word) => {
2621 Some(MetaItemKind::List(ref items)) => {
2623 inline_span = Some(attr.span);
2624 if items.len() != 1 {
2626 tcx.sess.diagnostic(),
2629 "expected one argument"
2632 } else if list_contains_name(&items[..], sym::always) {
2634 } else if list_contains_name(&items[..], sym::never) {
2638 tcx.sess.diagnostic(),
2647 Some(MetaItemKind::NameValue(_)) => ia,
2652 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2653 if attr.path != sym::optimize {
2656 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2657 match attr.meta().map(|i| i.node) {
2658 Some(MetaItemKind::Word) => {
2659 err(attr.span, "expected one argument");
2662 Some(MetaItemKind::List(ref items)) => {
2664 inline_span = Some(attr.span);
2665 if items.len() != 1 {
2666 err(attr.span, "expected one argument");
2668 } else if list_contains_name(&items[..], sym::size) {
2670 } else if list_contains_name(&items[..], sym::speed) {
2673 err(items[0].span(), "invalid argument");
2677 Some(MetaItemKind::NameValue(_)) => ia,
2682 // If a function uses #[target_feature] it can't be inlined into general
2683 // purpose functions as they wouldn't have the right target features
2684 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2686 if codegen_fn_attrs.target_features.len() > 0 {
2687 if codegen_fn_attrs.inline == InlineAttr::Always {
2688 if let Some(span) = inline_span {
2691 "cannot use #[inline(always)] with \
2698 // Weak lang items have the same semantics as "std internal" symbols in the
2699 // sense that they're preserved through all our LTO passes and only
2700 // strippable by the linker.
2702 // Additionally weak lang items have predetermined symbol names.
2703 if tcx.is_weak_lang_item(id) {
2704 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2706 if let Some(name) = weak_lang_items::link_name(&attrs) {
2707 codegen_fn_attrs.export_name = Some(name);
2708 codegen_fn_attrs.link_name = Some(name);
2711 // Internal symbols to the standard library all have no_mangle semantics in
2712 // that they have defined symbol names present in the function name. This
2713 // also applies to weak symbols where they all have known symbol names.
2714 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2715 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;