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, ToPolyTraitRef, Ty, TyCtxt};
31 use rustc::ty::{ReprOptions, ToPredicate};
32 use rustc::util::captures::Captures;
33 use rustc::util::nodemap::FxHashMap;
34 use rustc_data_structures::sync::Lrc;
35 use rustc_target::spec::abi;
38 use syntax::ast::{Ident, MetaItemKind};
39 use syntax::attr::{InlineAttr, OptimizeAttr, list_contains_name, mark_used};
40 use syntax::source_map::Spanned;
41 use syntax::feature_gate;
42 use syntax::symbol::{keywords, Symbol, sym};
43 use syntax_pos::{Span, DUMMY_SP};
45 use rustc::hir::def::{CtorKind, Res, DefKind};
47 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
48 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
49 use rustc::hir::GenericParamKind;
50 use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
54 struct OnlySelfBounds(bool);
56 ///////////////////////////////////////////////////////////////////////////
59 fn collect_mod_item_types<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
60 tcx.hir().visit_item_likes_in_module(
62 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor()
66 pub fn provide(providers: &mut Providers<'_>) {
67 *providers = Providers {
71 predicates_defined_on,
72 explicit_predicates_of,
74 type_param_predicates,
83 collect_mod_item_types,
88 ///////////////////////////////////////////////////////////////////////////
90 /// Context specific to some particular item. This is what implements
91 /// `AstConv`. It has information about the predicates that are defined
92 /// on the trait. Unfortunately, this predicate information is
93 /// available in various different forms at various points in the
94 /// process. So we can't just store a pointer to e.g., the AST or the
95 /// parsed ty form, we have to be more flexible. To this end, the
96 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
97 /// `get_type_parameter_bounds` requests, drawing the information from
98 /// the AST (`hir::Generics`), recursively.
99 pub struct ItemCtxt<'a, 'tcx: 'a> {
100 tcx: TyCtxt<'a, 'tcx, 'tcx>,
104 ///////////////////////////////////////////////////////////////////////////
106 struct CollectItemTypesVisitor<'a, 'tcx: 'a> {
107 tcx: TyCtxt<'a, 'tcx, 'tcx>,
110 impl<'a, 'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'a, 'tcx> {
111 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
112 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
115 fn visit_item(&mut self, item: &'tcx hir::Item) {
116 convert_item(self.tcx, item.hir_id);
117 intravisit::walk_item(self, item);
120 fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
121 for param in &generics.params {
123 hir::GenericParamKind::Lifetime { .. } => {}
124 hir::GenericParamKind::Type {
127 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
128 self.tcx.type_of(def_id);
130 hir::GenericParamKind::Type { .. } => {}
131 hir::GenericParamKind::Const { .. } => {
132 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
133 self.tcx.type_of(def_id);
137 intravisit::walk_generics(self, generics);
140 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
141 if let hir::ExprKind::Closure(..) = expr.node {
142 let def_id = self.tcx.hir().local_def_id_from_hir_id(expr.hir_id);
143 self.tcx.generics_of(def_id);
144 self.tcx.type_of(def_id);
146 intravisit::walk_expr(self, expr);
149 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
150 convert_trait_item(self.tcx, trait_item.hir_id);
151 intravisit::walk_trait_item(self, trait_item);
154 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
155 convert_impl_item(self.tcx, impl_item.hir_id);
156 intravisit::walk_impl_item(self, impl_item);
160 ///////////////////////////////////////////////////////////////////////////
161 // Utility types and common code for the above passes.
163 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
164 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_def_id: DefId) -> ItemCtxt<'a, 'tcx> {
165 ItemCtxt { tcx, item_def_id }
169 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
170 pub fn to_ty(&self, ast_ty: &hir::Ty) -> Ty<'tcx> {
171 AstConv::ast_ty_to_ty(self, ast_ty)
175 impl<'a, 'tcx> AstConv<'tcx, 'tcx> for ItemCtxt<'a, 'tcx> {
176 fn tcx<'b>(&'b self) -> TyCtxt<'b, 'tcx, 'tcx> {
180 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId)
181 -> Lrc<ty::GenericPredicates<'tcx>> {
184 .type_param_predicates((self.item_def_id, def_id))
190 _def: Option<&ty::GenericParamDef>,
191 ) -> Option<ty::Region<'tcx>> {
195 fn ty_infer(&self, span: Span) -> Ty<'tcx> {
200 "the type placeholder `_` is not allowed within types on item signatures"
201 ).span_label(span, "not allowed in type signatures")
207 fn projected_ty_from_poly_trait_ref(
211 poly_trait_ref: ty::PolyTraitRef<'tcx>,
213 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
214 self.tcx().mk_projection(item_def_id, trait_ref.substs)
216 // no late-bound regions, we can just ignore the binder
221 "cannot extract an associated type from a higher-ranked trait bound \
228 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
229 // types in item signatures are not normalized, to avoid undue
234 fn set_tainted_by_errors(&self) {
235 // no obvious place to track this, just let it go
238 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
239 // no place to record types from signatures?
243 fn type_param_predicates<'a, 'tcx>(
244 tcx: TyCtxt<'a, 'tcx, 'tcx>,
245 (item_def_id, def_id): (DefId, DefId),
246 ) -> Lrc<ty::GenericPredicates<'tcx>> {
249 // In the AST, bounds can derive from two places. Either
250 // written inline like `<T : Foo>` or in a where clause like
253 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
254 let param_owner = tcx.hir().ty_param_owner(param_id);
255 let param_owner_def_id = tcx.hir().local_def_id_from_hir_id(param_owner);
256 let generics = tcx.generics_of(param_owner_def_id);
257 let index = generics.param_def_id_to_index[&def_id];
258 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id).as_interned_str());
260 // Don't look for bounds where the type parameter isn't in scope.
261 let parent = if item_def_id == param_owner_def_id {
264 tcx.generics_of(item_def_id).parent
267 let mut result = parent.map_or_else(
268 || Lrc::new(ty::GenericPredicates {
273 let icx = ItemCtxt::new(tcx, parent);
274 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
278 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
279 let ast_generics = match tcx.hir().get_by_hir_id(item_hir_id) {
280 Node::TraitItem(item) => &item.generics,
282 Node::ImplItem(item) => &item.generics,
284 Node::Item(item) => {
286 ItemKind::Fn(.., ref generics, _)
287 | ItemKind::Impl(_, _, _, ref generics, ..)
288 | ItemKind::Ty(_, ref generics)
289 | ItemKind::Existential(ExistTy {
294 | ItemKind::Enum(_, ref generics)
295 | ItemKind::Struct(_, ref generics)
296 | ItemKind::Union(_, ref generics) => generics,
297 ItemKind::Trait(_, _, ref generics, ..) => {
298 // Implied `Self: Trait` and supertrait bounds.
299 if param_id == item_hir_id {
300 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
301 Lrc::make_mut(&mut result)
303 .push((identity_trait_ref.to_predicate(), item.span));
311 Node::ForeignItem(item) => match item.node {
312 ForeignItemKind::Fn(_, _, ref generics) => generics,
319 let icx = ItemCtxt::new(tcx, item_def_id);
320 Lrc::make_mut(&mut result)
322 .extend(icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty,
323 OnlySelfBounds(true)));
327 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
328 /// Finds bounds from `hir::Generics`. This requires scanning through the
329 /// AST. We do this to avoid having to convert *all* the bounds, which
330 /// would create artificial cycles. Instead we can only convert the
331 /// bounds for a type parameter `X` if `X::Foo` is used.
332 fn type_parameter_bounds_in_generics(
334 ast_generics: &hir::Generics,
335 param_id: hir::HirId,
337 only_self_bounds: OnlySelfBounds,
338 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
339 let from_ty_params = ast_generics
342 .filter_map(|param| match param.kind {
343 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
346 .flat_map(|bounds| bounds.iter())
347 .flat_map(|b| predicates_from_bound(self, ty, b));
349 let from_where_clauses = ast_generics
353 .filter_map(|wp| match *wp {
354 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
358 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
360 } else if !only_self_bounds.0 {
361 Some(self.to_ty(&bp.bounded_ty))
365 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
367 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
369 from_ty_params.chain(from_where_clauses).collect()
373 /// Tests whether this is the AST for a reference to the type
374 /// parameter with ID `param_id`. We use this so as to avoid running
375 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
376 /// conversion of the type to avoid inducing unnecessary cycles.
377 fn is_param<'a, 'tcx>(
378 tcx: TyCtxt<'a, 'tcx, 'tcx>,
380 param_id: hir::HirId,
382 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.node {
384 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
385 def_id == tcx.hir().local_def_id_from_hir_id(param_id)
394 fn convert_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_id: hir::HirId) {
395 let it = tcx.hir().expect_item_by_hir_id(item_id);
396 debug!("convert: item {} with id {}", it.ident, it.hir_id);
397 let def_id = tcx.hir().local_def_id_from_hir_id(item_id);
399 // These don't define types.
400 hir::ItemKind::ExternCrate(_)
401 | hir::ItemKind::Use(..)
402 | hir::ItemKind::Mod(_)
403 | hir::ItemKind::GlobalAsm(_) => {}
404 hir::ItemKind::ForeignMod(ref foreign_mod) => {
405 for item in &foreign_mod.items {
406 let def_id = tcx.hir().local_def_id_from_hir_id(item.hir_id);
407 tcx.generics_of(def_id);
409 tcx.predicates_of(def_id);
410 if let hir::ForeignItemKind::Fn(..) = item.node {
415 hir::ItemKind::Enum(ref enum_definition, _) => {
416 tcx.generics_of(def_id);
418 tcx.predicates_of(def_id);
419 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
421 hir::ItemKind::Impl(..) => {
422 tcx.generics_of(def_id);
424 tcx.impl_trait_ref(def_id);
425 tcx.predicates_of(def_id);
427 hir::ItemKind::Trait(..) => {
428 tcx.generics_of(def_id);
429 tcx.trait_def(def_id);
430 tcx.at(it.span).super_predicates_of(def_id);
431 tcx.predicates_of(def_id);
433 hir::ItemKind::TraitAlias(..) => {
434 tcx.generics_of(def_id);
435 tcx.at(it.span).super_predicates_of(def_id);
436 tcx.predicates_of(def_id);
438 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
439 tcx.generics_of(def_id);
441 tcx.predicates_of(def_id);
443 for f in struct_def.fields() {
444 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
445 tcx.generics_of(def_id);
447 tcx.predicates_of(def_id);
450 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
451 convert_variant_ctor(tcx, ctor_hir_id);
455 // Desugared from `impl Trait` -> visited by the function's return type
456 hir::ItemKind::Existential(hir::ExistTy {
457 impl_trait_fn: Some(_),
461 hir::ItemKind::Existential(..)
462 | hir::ItemKind::Ty(..)
463 | hir::ItemKind::Static(..)
464 | hir::ItemKind::Const(..)
465 | hir::ItemKind::Fn(..) => {
466 tcx.generics_of(def_id);
468 tcx.predicates_of(def_id);
469 if let hir::ItemKind::Fn(..) = it.node {
476 fn convert_trait_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, trait_item_id: hir::HirId) {
477 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
478 let def_id = tcx.hir().local_def_id_from_hir_id(trait_item.hir_id);
479 tcx.generics_of(def_id);
481 match trait_item.node {
482 hir::TraitItemKind::Const(..)
483 | hir::TraitItemKind::Type(_, Some(_))
484 | hir::TraitItemKind::Method(..) => {
486 if let hir::TraitItemKind::Method(..) = trait_item.node {
491 hir::TraitItemKind::Type(_, None) => {}
494 tcx.predicates_of(def_id);
497 fn convert_impl_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, impl_item_id: hir::HirId) {
498 let def_id = tcx.hir().local_def_id_from_hir_id(impl_item_id);
499 tcx.generics_of(def_id);
501 tcx.predicates_of(def_id);
502 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).node {
507 fn convert_variant_ctor<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ctor_id: hir::HirId) {
508 let def_id = tcx.hir().local_def_id_from_hir_id(ctor_id);
509 tcx.generics_of(def_id);
511 tcx.predicates_of(def_id);
514 fn convert_enum_variant_types<'a, 'tcx>(
515 tcx: TyCtxt<'a, 'tcx, 'tcx>,
517 variants: &[hir::Variant],
519 let def = tcx.adt_def(def_id);
520 let repr_type = def.repr.discr_type();
521 let initial = repr_type.initial_discriminant(tcx);
522 let mut prev_discr = None::<Discr<'tcx>>;
524 // fill the discriminant values and field types
525 for variant in variants {
526 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
528 if let Some(ref e) = variant.node.disr_expr {
529 let expr_did = tcx.hir().local_def_id_from_hir_id(e.hir_id);
530 def.eval_explicit_discr(tcx, expr_did)
531 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
538 "enum discriminant overflowed"
541 format!("overflowed on value after {}", prev_discr.unwrap()),
543 "explicitly set `{} = {}` if that is desired outcome",
544 variant.node.ident, wrapped_discr
548 }.unwrap_or(wrapped_discr),
551 for f in variant.node.data.fields() {
552 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
553 tcx.generics_of(def_id);
555 tcx.predicates_of(def_id);
558 // Convert the ctor, if any. This also registers the variant as
560 if let Some(ctor_hir_id) = variant.node.data.ctor_hir_id() {
561 convert_variant_ctor(tcx, ctor_hir_id);
566 fn convert_variant<'a, 'tcx>(
567 tcx: TyCtxt<'a, 'tcx, 'tcx>,
568 variant_did: Option<DefId>,
569 ctor_did: Option<DefId>,
571 discr: ty::VariantDiscr,
572 def: &hir::VariantData,
573 adt_kind: ty::AdtKind,
575 ) -> ty::VariantDef {
576 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
577 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
582 let fid = tcx.hir().local_def_id_from_hir_id(f.hir_id);
583 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
584 if let Some(prev_span) = dup_span {
589 "field `{}` is already declared",
591 ).span_label(f.span, "field already declared")
592 .span_label(prev_span, format!("`{}` first declared here", f.ident))
595 seen_fields.insert(f.ident.modern(), f.span);
601 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
605 let recovered = match def {
606 hir::VariantData::Struct(_, r) => *r,
616 CtorKind::from_hir(def),
623 fn adt_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::AdtDef {
626 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
627 let item = match tcx.hir().get_by_hir_id(hir_id) {
628 Node::Item(item) => item,
632 let repr = ReprOptions::new(tcx, def_id);
633 let (kind, variants) = match item.node {
634 ItemKind::Enum(ref def, _) => {
635 let mut distance_from_explicit = 0;
636 let variants = def.variants
639 let variant_did = Some(tcx.hir().local_def_id_from_hir_id(v.node.id));
640 let ctor_did = v.node.data.ctor_hir_id()
641 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
643 let discr = if let Some(ref e) = v.node.disr_expr {
644 distance_from_explicit = 0;
645 ty::VariantDiscr::Explicit(tcx.hir().local_def_id_from_hir_id(e.hir_id))
647 ty::VariantDiscr::Relative(distance_from_explicit)
649 distance_from_explicit += 1;
651 convert_variant(tcx, variant_did, ctor_did, v.node.ident, discr,
652 &v.node.data, AdtKind::Enum, def_id)
656 (AdtKind::Enum, variants)
658 ItemKind::Struct(ref def, _) => {
659 let variant_did = None;
660 let ctor_did = def.ctor_hir_id()
661 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
663 let variants = std::iter::once(convert_variant(
664 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
665 AdtKind::Struct, def_id,
668 (AdtKind::Struct, variants)
670 ItemKind::Union(ref def, _) => {
671 let variant_did = None;
672 let ctor_did = def.ctor_hir_id()
673 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
675 let variants = std::iter::once(convert_variant(
676 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
677 AdtKind::Union, def_id,
680 (AdtKind::Union, variants)
684 tcx.alloc_adt_def(def_id, kind, variants, repr)
687 /// Ensures that the super-predicates of the trait with `DefId`
688 /// trait_def_id are converted and stored. This also ensures that
689 /// the transitive super-predicates are converted;
690 fn super_predicates_of<'a, 'tcx>(
691 tcx: TyCtxt<'a, 'tcx, 'tcx>,
693 ) -> Lrc<ty::GenericPredicates<'tcx>> {
694 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
695 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
697 let item = match tcx.hir().get_by_hir_id(trait_hir_id) {
698 Node::Item(item) => item,
699 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
702 let (generics, bounds) = match item.node {
703 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
704 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
705 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
708 let icx = ItemCtxt::new(tcx, trait_def_id);
710 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo : Bar + Zed`.
711 let self_param_ty = tcx.mk_self_type();
712 let superbounds1 = compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
714 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
716 // Convert any explicit superbounds in the where clause,
717 // e.g., `trait Foo where Self : Bar`.
718 // In the case of trait aliases, however, we include all bounds in the where clause,
719 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
720 // as one of its "superpredicates".
721 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
722 let superbounds2 = icx.type_parameter_bounds_in_generics(
723 generics, item.hir_id, self_param_ty, OnlySelfBounds(!is_trait_alias));
725 // Combine the two lists to form the complete set of superbounds:
726 let superbounds: Vec<_> = superbounds1.into_iter().chain(superbounds2).collect();
728 // Now require that immediate supertraits are converted,
729 // which will, in turn, reach indirect supertraits.
730 for &(pred, span) in &superbounds {
731 debug!("superbound: {:?}", pred);
732 if let ty::Predicate::Trait(bound) = pred {
733 tcx.at(span).super_predicates_of(bound.def_id());
737 Lrc::new(ty::GenericPredicates {
739 predicates: superbounds,
743 fn trait_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::TraitDef {
744 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
745 let item = tcx.hir().expect_item_by_hir_id(hir_id);
747 let (is_auto, unsafety) = match item.node {
748 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
749 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
750 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
753 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
754 if paren_sugar && !tcx.features().unboxed_closures {
755 let mut err = tcx.sess.struct_span_err(
757 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
758 which traits can use parenthetical notation",
762 "add `#![feature(unboxed_closures)]` to \
763 the crate attributes to use it"
768 let is_marker = tcx.has_attr(def_id, sym::marker);
769 let def_path_hash = tcx.def_path_hash(def_id);
770 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
771 tcx.alloc_trait_def(def)
774 fn has_late_bound_regions<'a, 'tcx>(
775 tcx: TyCtxt<'a, 'tcx, 'tcx>,
778 struct LateBoundRegionsDetector<'a, 'tcx: 'a> {
779 tcx: TyCtxt<'a, 'tcx, 'tcx>,
780 outer_index: ty::DebruijnIndex,
781 has_late_bound_regions: Option<Span>,
784 impl<'a, 'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'a, 'tcx> {
785 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
786 NestedVisitorMap::None
789 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
790 if self.has_late_bound_regions.is_some() {
794 hir::TyKind::BareFn(..) => {
795 self.outer_index.shift_in(1);
796 intravisit::walk_ty(self, ty);
797 self.outer_index.shift_out(1);
799 _ => intravisit::walk_ty(self, ty),
803 fn visit_poly_trait_ref(
805 tr: &'tcx hir::PolyTraitRef,
806 m: hir::TraitBoundModifier,
808 if self.has_late_bound_regions.is_some() {
811 self.outer_index.shift_in(1);
812 intravisit::walk_poly_trait_ref(self, tr, m);
813 self.outer_index.shift_out(1);
816 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
817 if self.has_late_bound_regions.is_some() {
821 match self.tcx.named_region(lt.hir_id) {
822 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
823 Some(rl::Region::LateBound(debruijn, _, _))
824 | Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
825 Some(rl::Region::LateBound(..))
826 | Some(rl::Region::LateBoundAnon(..))
827 | Some(rl::Region::Free(..))
829 self.has_late_bound_regions = Some(lt.span);
835 fn has_late_bound_regions<'a, 'tcx>(
836 tcx: TyCtxt<'a, 'tcx, 'tcx>,
837 generics: &'tcx hir::Generics,
838 decl: &'tcx hir::FnDecl,
840 let mut visitor = LateBoundRegionsDetector {
842 outer_index: ty::INNERMOST,
843 has_late_bound_regions: None,
845 for param in &generics.params {
846 if let GenericParamKind::Lifetime { .. } = param.kind {
847 if tcx.is_late_bound(param.hir_id) {
848 return Some(param.span);
852 visitor.visit_fn_decl(decl);
853 visitor.has_late_bound_regions
857 Node::TraitItem(item) => match item.node {
858 hir::TraitItemKind::Method(ref sig, _) => {
859 has_late_bound_regions(tcx, &item.generics, &sig.decl)
863 Node::ImplItem(item) => match item.node {
864 hir::ImplItemKind::Method(ref sig, _) => {
865 has_late_bound_regions(tcx, &item.generics, &sig.decl)
869 Node::ForeignItem(item) => match item.node {
870 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
871 has_late_bound_regions(tcx, generics, fn_decl)
875 Node::Item(item) => match item.node {
876 hir::ItemKind::Fn(ref fn_decl, .., ref generics, _) => {
877 has_late_bound_regions(tcx, generics, fn_decl)
885 fn generics_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::Generics {
888 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
890 let node = tcx.hir().get_by_hir_id(hir_id);
891 let parent_def_id = match node {
892 Node::ImplItem(_) | Node::TraitItem(_) | Node::Variant(_) |
893 Node::Ctor(..) | Node::Field(_) => {
894 let parent_id = tcx.hir().get_parent_item(hir_id);
895 Some(tcx.hir().local_def_id_from_hir_id(parent_id))
897 Node::Expr(&hir::Expr {
898 node: hir::ExprKind::Closure(..),
900 }) => Some(tcx.closure_base_def_id(def_id)),
901 Node::Item(item) => match item.node {
902 ItemKind::Existential(hir::ExistTy { impl_trait_fn, .. }) => impl_trait_fn,
908 let mut opt_self = None;
909 let mut allow_defaults = false;
911 let no_generics = hir::Generics::empty();
912 let ast_generics = match node {
913 Node::TraitItem(item) => &item.generics,
915 Node::ImplItem(item) => &item.generics,
917 Node::Item(item) => {
919 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
923 ItemKind::Ty(_, ref generics)
924 | ItemKind::Enum(_, ref generics)
925 | ItemKind::Struct(_, ref generics)
926 | ItemKind::Existential(hir::ExistTy { ref generics, .. })
927 | ItemKind::Union(_, ref generics) => {
928 allow_defaults = true;
932 ItemKind::Trait(_, _, ref generics, ..)
933 | ItemKind::TraitAlias(ref generics, ..) => {
934 // Add in the self type parameter.
936 // Something of a hack: use the node id for the trait, also as
937 // the node id for the Self type parameter.
938 let param_id = item.hir_id;
940 opt_self = Some(ty::GenericParamDef {
942 name: keywords::SelfUpper.name().as_interned_str(),
943 def_id: tcx.hir().local_def_id_from_hir_id(param_id),
944 pure_wrt_drop: false,
945 kind: ty::GenericParamDefKind::Type {
947 object_lifetime_default: rl::Set1::Empty,
952 allow_defaults = true;
960 Node::ForeignItem(item) => match item.node {
961 ForeignItemKind::Static(..) => &no_generics,
962 ForeignItemKind::Fn(_, _, ref generics) => generics,
963 ForeignItemKind::Type => &no_generics,
969 let has_self = opt_self.is_some();
970 let mut parent_has_self = false;
971 let mut own_start = has_self as u32;
972 let parent_count = parent_def_id.map_or(0, |def_id| {
973 let generics = tcx.generics_of(def_id);
974 assert_eq!(has_self, false);
975 parent_has_self = generics.has_self;
976 own_start = generics.count() as u32;
977 generics.parent_count + generics.params.len()
980 let mut params: Vec<_> = opt_self.into_iter().collect();
982 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
986 .map(|(i, param)| ty::GenericParamDef {
987 name: param.name.ident().as_interned_str(),
988 index: own_start + i as u32,
989 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
990 pure_wrt_drop: param.pure_wrt_drop,
991 kind: ty::GenericParamDefKind::Lifetime,
995 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
997 // Now create the real type parameters.
998 let type_start = own_start - has_self as u32 + params.len() as u32;
1004 .filter_map(|param| {
1005 let kind = match param.kind {
1006 GenericParamKind::Type {
1011 if param.name.ident().name == keywords::SelfUpper.name() {
1014 "`Self` should not be the name of a regular parameter"
1018 if !allow_defaults && default.is_some() {
1019 if !tcx.features().default_type_parameter_fallback {
1021 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1025 "defaults for type parameters are only allowed in \
1026 `struct`, `enum`, `type`, or `trait` definitions."
1032 ty::GenericParamDefKind::Type {
1033 has_default: default.is_some(),
1034 object_lifetime_default: object_lifetime_defaults
1036 .map_or(rl::Set1::Empty, |o| o[i]),
1040 GenericParamKind::Const { .. } => {
1041 if param.name.ident().name == keywords::SelfUpper.name() {
1044 "`Self` should not be the name of a regular parameter",
1048 ty::GenericParamDefKind::Const
1053 let param_def = ty::GenericParamDef {
1054 index: type_start + i as u32,
1055 name: param.name.ident().as_interned_str(),
1056 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
1057 pure_wrt_drop: param.pure_wrt_drop,
1065 // provide junk type parameter defs - the only place that
1066 // cares about anything but the length is instantiation,
1067 // and we don't do that for closures.
1068 if let Node::Expr(&hir::Expr {
1069 node: hir::ExprKind::Closure(.., gen),
1073 let dummy_args = if gen.is_some() {
1074 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1076 &["<closure_kind>", "<closure_signature>"][..]
1083 .map(|(i, &arg)| ty::GenericParamDef {
1084 index: type_start + i as u32,
1085 name: Symbol::intern(arg).as_interned_str(),
1087 pure_wrt_drop: false,
1088 kind: ty::GenericParamDefKind::Type {
1090 object_lifetime_default: rl::Set1::Empty,
1096 if let Some(upvars) = tcx.upvars(def_id) {
1097 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1098 ty::GenericParamDef {
1099 index: type_start + i,
1100 name: Symbol::intern("<upvar>").as_interned_str(),
1102 pure_wrt_drop: false,
1103 kind: ty::GenericParamDefKind::Type {
1105 object_lifetime_default: rl::Set1::Empty,
1113 let param_def_id_to_index = params
1115 .map(|param| (param.def_id, param.index))
1118 tcx.alloc_generics(ty::Generics {
1119 parent: parent_def_id,
1122 param_def_id_to_index,
1123 has_self: has_self || parent_has_self,
1124 has_late_bound_regions: has_late_bound_regions(tcx, node),
1128 fn report_assoc_ty_on_inherent_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, span: Span) {
1133 "associated types are not yet supported in inherent impls (see #8995)"
1137 fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
1138 checked_type_of(tcx, def_id, true).unwrap()
1141 /// Same as [`type_of`] but returns [`Option`] instead of failing.
1143 /// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
1144 /// you'd better just call [`type_of`] directly.
1145 pub fn checked_type_of<'a, 'tcx>(
1146 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1149 ) -> Option<Ty<'tcx>> {
1152 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1153 Some(hir_id) => hir_id,
1158 bug!("invalid node");
1162 let icx = ItemCtxt::new(tcx, def_id);
1164 Some(match tcx.hir().get_by_hir_id(hir_id) {
1165 Node::TraitItem(item) => match item.node {
1166 TraitItemKind::Method(..) => {
1167 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1168 tcx.mk_fn_def(def_id, substs)
1170 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1171 TraitItemKind::Type(_, None) => {
1175 span_bug!(item.span, "associated type missing default");
1179 Node::ImplItem(item) => match item.node {
1180 ImplItemKind::Method(..) => {
1181 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1182 tcx.mk_fn_def(def_id, substs)
1184 ImplItemKind::Const(ref ty, _) => icx.to_ty(ty),
1185 ImplItemKind::Existential(_) => {
1187 .impl_trait_ref(tcx.hir().get_parent_did_by_hir_id(hir_id))
1190 report_assoc_ty_on_inherent_impl(tcx, item.span);
1193 find_existential_constraints(tcx, def_id)
1195 ImplItemKind::Type(ref ty) => {
1197 .impl_trait_ref(tcx.hir().get_parent_did_by_hir_id(hir_id))
1200 report_assoc_ty_on_inherent_impl(tcx, item.span);
1207 Node::Item(item) => {
1209 ItemKind::Static(ref t, ..)
1210 | ItemKind::Const(ref t, _)
1211 | ItemKind::Ty(ref t, _)
1212 | ItemKind::Impl(.., ref t, _) => icx.to_ty(t),
1213 ItemKind::Fn(..) => {
1214 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1215 tcx.mk_fn_def(def_id, substs)
1217 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1218 let def = tcx.adt_def(def_id);
1219 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1220 tcx.mk_adt(def, substs)
1222 ItemKind::Existential(hir::ExistTy {
1223 impl_trait_fn: None,
1225 }) => find_existential_constraints(tcx, def_id),
1226 // existential types desugared from impl Trait
1227 ItemKind::Existential(hir::ExistTy {
1228 impl_trait_fn: Some(owner),
1231 tcx.typeck_tables_of(owner)
1232 .concrete_existential_types
1234 .map(|opaque| opaque.concrete_type)
1235 .unwrap_or_else(|| {
1236 // This can occur if some error in the
1237 // owner fn prevented us from populating
1238 // the `concrete_existential_types` table.
1239 tcx.sess.delay_span_bug(
1242 "owner {:?} has no existential type for {:?} in its tables",
1250 | ItemKind::TraitAlias(..)
1252 | ItemKind::ForeignMod(..)
1253 | ItemKind::GlobalAsm(..)
1254 | ItemKind::ExternCrate(..)
1255 | ItemKind::Use(..) => {
1261 "compute_type_of_item: unexpected item type: {:?}",
1268 Node::ForeignItem(foreign_item) => match foreign_item.node {
1269 ForeignItemKind::Fn(..) => {
1270 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1271 tcx.mk_fn_def(def_id, substs)
1273 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1274 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1277 Node::Ctor(&ref def) | Node::Variant(&Spanned {
1278 node: hir::VariantKind { data: ref def, .. },
1281 VariantData::Unit(..) | VariantData::Struct(..) => {
1282 tcx.type_of(tcx.hir().get_parent_did_by_hir_id(hir_id))
1284 VariantData::Tuple(..) => {
1285 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1286 tcx.mk_fn_def(def_id, substs)
1290 Node::Field(field) => icx.to_ty(&field.ty),
1292 Node::Expr(&hir::Expr {
1293 node: hir::ExprKind::Closure(.., gen),
1297 return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
1300 let substs = ty::ClosureSubsts {
1301 substs: InternalSubsts::identity_for_item(tcx, def_id),
1304 tcx.mk_closure(def_id, substs)
1307 Node::AnonConst(_) => {
1308 let parent_node = tcx.hir().get_by_hir_id(tcx.hir().get_parent_node_by_hir_id(hir_id));
1311 node: hir::TyKind::Array(_, ref constant),
1314 | Node::Ty(&hir::Ty {
1315 node: hir::TyKind::Typeof(ref constant),
1318 | Node::Expr(&hir::Expr {
1319 node: ExprKind::Repeat(_, ref constant),
1321 }) if constant.hir_id == hir_id =>
1326 Node::Variant(&Spanned {
1329 disr_expr: Some(ref e),
1333 }) if e.hir_id == hir_id =>
1335 tcx.adt_def(tcx.hir().get_parent_did_by_hir_id(hir_id))
1341 Node::Ty(&hir::Ty { node: hir::TyKind::Path(_), .. }) |
1342 Node::Expr(&hir::Expr { node: ExprKind::Struct(..), .. }) |
1343 Node::Expr(&hir::Expr { node: ExprKind::Path(_), .. }) => {
1344 let path = match parent_node {
1345 Node::Ty(&hir::Ty { node: hir::TyKind::Path(ref path), .. }) |
1346 Node::Expr(&hir::Expr { node: ExprKind::Path(ref path), .. }) => {
1349 Node::Expr(&hir::Expr { node: ExprKind::Struct(ref path, ..), .. }) => {
1352 _ => unreachable!(),
1356 QPath::Resolved(_, ref path) => {
1357 let mut arg_index = 0;
1358 let mut found_const = false;
1359 for seg in &path.segments {
1360 if let Some(generic_args) = &seg.args {
1361 let args = &generic_args.args;
1363 if let GenericArg::Const(ct) = arg {
1364 if ct.value.hir_id == hir_id {
1373 // Sanity check to make sure everything is as expected.
1378 bug!("no arg matching AnonConst in path")
1381 // We've encountered an `AnonConst` in some path, so we need to
1382 // figure out which generic parameter it corresponds to and return
1383 // the relevant type.
1384 Res::Def(DefKind::Struct, def_id)
1385 | Res::Def(DefKind::Union, def_id)
1386 | Res::Def(DefKind::Enum, def_id)
1387 | Res::Def(DefKind::Fn, def_id) => {
1388 let generics = tcx.generics_of(def_id);
1389 let mut param_index = 0;
1390 for param in &generics.params {
1391 if let ty::GenericParamDefKind::Const = param.kind {
1392 if param_index == arg_index {
1393 return Some(tcx.type_of(param.def_id));
1398 // This is no generic parameter associated with the arg. This is
1399 // probably from an extra arg where one is not needed.
1400 return Some(tcx.types.err);
1402 Res::Err => tcx.types.err,
1407 tcx.sess.delay_span_bug(
1410 "unexpected const parent path def {:?}", x
1421 tcx.sess.delay_span_bug(
1424 "unexpected const parent path {:?}", x
1436 tcx.sess.delay_span_bug(
1439 "unexpected const parent in type_of_def_id(): {:?}", x
1447 Node::GenericParam(param) => match ¶m.kind {
1448 hir::GenericParamKind::Type { default: Some(ref ty), .. } |
1449 hir::GenericParamKind::Const { ref ty, .. } => {
1456 bug!("unexpected non-type Node::GenericParam: {:?}", x)
1464 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1469 fn find_existential_constraints<'a, 'tcx>(
1470 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1473 use rustc::hir::{ImplItem, Item, TraitItem};
1475 struct ConstraintLocator<'a, 'tcx: 'a> {
1476 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1478 // First found type span, actual type, mapping from the existential type's generic
1479 // parameters to the concrete type's generic parameters
1481 // The mapping is an index for each use site of a generic parameter in the concrete type
1483 // The indices index into the generic parameters on the existential type.
1484 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1487 impl<'a, 'tcx> ConstraintLocator<'a, 'tcx> {
1488 fn check(&mut self, def_id: DefId) {
1489 trace!("checking {:?}", def_id);
1490 // don't try to check items that cannot possibly constrain the type
1491 if !self.tcx.has_typeck_tables(def_id) {
1492 trace!("no typeck tables for {:?}", def_id);
1497 .typeck_tables_of(def_id)
1498 .concrete_existential_types
1500 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1501 // FIXME(oli-obk): trace the actual span from inference to improve errors
1502 let span = self.tcx.def_span(def_id);
1503 // used to quickly look up the position of a generic parameter
1504 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1505 // skip binder is ok, since we only use this to find generic parameters and their
1507 for (idx, subst) in substs.iter().enumerate() {
1508 if let UnpackedKind::Type(ty) = subst.unpack() {
1509 if let ty::Param(p) = ty.sty {
1510 if index_map.insert(p, idx).is_some() {
1511 // there was already an entry for `p`, meaning a generic parameter
1513 self.tcx.sess.span_err(
1515 &format!("defining existential type use restricts existential \
1516 type by using the generic parameter `{}` twice", p.name),
1521 self.tcx.sess.delay_span_bug(
1524 "non-defining exist ty use in defining scope: {:?}, {:?}",
1525 concrete_type, substs,
1531 // compute the index within the existential type for each generic parameter used in
1532 // the concrete type
1533 let indices = concrete_type
1534 .subst(self.tcx, substs)
1536 .filter_map(|t| match &t.sty {
1537 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1540 let is_param = |ty: Ty<'_>| match ty.sty {
1541 ty::Param(_) => true,
1544 if !substs.types().all(is_param) {
1545 self.tcx.sess.span_err(
1547 "defining existential type use does not fully define existential type",
1549 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1550 let mut ty = concrete_type.walk().fuse();
1551 let mut p_ty = prev_ty.walk().fuse();
1552 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.sty, &p.sty) {
1553 // type parameters are equal to any other type parameter for the purpose of
1554 // concrete type equality, as it is possible to obtain the same type just
1555 // by passing matching parameters to a function.
1556 (ty::Param(_), ty::Param(_)) => true,
1559 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1560 // found different concrete types for the existential type
1561 let mut err = self.tcx.sess.struct_span_err(
1563 "concrete type differs from previous defining existential type use",
1567 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1569 err.span_note(prev_span, "previous use here");
1571 } else if indices != *prev_indices {
1572 // found "same" concrete types, but the generic parameter order differs
1573 let mut err = self.tcx.sess.struct_span_err(
1575 "concrete type's generic parameters differ from previous defining use",
1577 use std::fmt::Write;
1578 let mut s = String::new();
1579 write!(s, "expected [").unwrap();
1580 let list = |s: &mut String, indices: &Vec<usize>| {
1581 let mut indices = indices.iter().cloned();
1582 if let Some(first) = indices.next() {
1583 write!(s, "`{}`", substs[first]).unwrap();
1585 write!(s, ", `{}`", substs[i]).unwrap();
1589 list(&mut s, prev_indices);
1590 write!(s, "], got [").unwrap();
1591 list(&mut s, &indices);
1592 write!(s, "]").unwrap();
1593 err.span_label(span, s);
1594 err.span_note(prev_span, "previous use here");
1598 self.found = Some((span, concrete_type, indices));
1604 impl<'a, 'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'a, 'tcx> {
1605 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1606 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1608 fn visit_item(&mut self, it: &'tcx Item) {
1609 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1610 // the existential type itself or its children are not within its reveal scope
1611 if def_id != self.def_id {
1613 intravisit::walk_item(self, it);
1616 fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
1617 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1618 // the existential type itself or its children are not within its reveal scope
1619 if def_id != self.def_id {
1621 intravisit::walk_impl_item(self, it);
1624 fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
1625 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1627 intravisit::walk_trait_item(self, it);
1631 let mut locator = ConstraintLocator {
1636 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1637 let parent = tcx.hir().get_parent_item(hir_id);
1639 trace!("parent_id: {:?}", parent);
1641 if parent == hir::CRATE_HIR_ID {
1642 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1644 trace!("parent: {:?}", tcx.hir().get_by_hir_id(parent));
1645 match tcx.hir().get_by_hir_id(parent) {
1646 Node::Item(ref it) => intravisit::walk_item(&mut locator, it),
1647 Node::ImplItem(ref it) => intravisit::walk_impl_item(&mut locator, it),
1648 Node::TraitItem(ref it) => intravisit::walk_trait_item(&mut locator, it),
1650 "{:?} is not a valid parent of an existential type item",
1656 match locator.found {
1657 Some((_, ty, _)) => ty,
1659 let span = tcx.def_span(def_id);
1660 tcx.sess.span_err(span, "could not find defining uses");
1666 fn fn_sig<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ty::PolyFnSig<'tcx> {
1668 use rustc::hir::Node::*;
1670 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1672 let icx = ItemCtxt::new(tcx, def_id);
1674 match tcx.hir().get_by_hir_id(hir_id) {
1675 TraitItem(hir::TraitItem {
1676 node: TraitItemKind::Method(sig, _),
1679 | ImplItem(hir::ImplItem {
1680 node: ImplItemKind::Method(sig, _),
1682 }) => AstConv::ty_of_fn(&icx, sig.header.unsafety, sig.header.abi, &sig.decl),
1685 node: ItemKind::Fn(decl, header, _, _),
1687 }) => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl),
1689 ForeignItem(&hir::ForeignItem {
1690 node: ForeignItemKind::Fn(ref fn_decl, _, _),
1693 let abi = tcx.hir().get_foreign_abi_by_hir_id(hir_id);
1694 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1697 Ctor(data) | Variant(Spanned {
1698 node: hir::VariantKind { data, .. },
1700 }) if data.ctor_hir_id().is_some() => {
1701 let ty = tcx.type_of(tcx.hir().get_parent_did_by_hir_id(hir_id));
1702 let inputs = data.fields()
1704 .map(|f| tcx.type_of(tcx.hir().local_def_id_from_hir_id(f.hir_id)));
1705 ty::Binder::bind(tcx.mk_fn_sig(
1709 hir::Unsafety::Normal,
1715 node: hir::ExprKind::Closure(..),
1718 // Closure signatures are not like other function
1719 // signatures and cannot be accessed through `fn_sig`. For
1720 // example, a closure signature excludes the `self`
1721 // argument. In any case they are embedded within the
1722 // closure type as part of the `ClosureSubsts`.
1725 // the signature of a closure, you should use the
1726 // `closure_sig` method on the `ClosureSubsts`:
1728 // closure_substs.closure_sig(def_id, tcx)
1730 // or, inside of an inference context, you can use
1732 // infcx.closure_sig(def_id, closure_substs)
1733 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1737 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1742 fn impl_trait_ref<'a, 'tcx>(
1743 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1745 ) -> Option<ty::TraitRef<'tcx>> {
1746 let icx = ItemCtxt::new(tcx, def_id);
1748 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1749 match tcx.hir().expect_item_by_hir_id(hir_id).node {
1750 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1751 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1752 let selfty = tcx.type_of(def_id);
1753 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1760 fn impl_polarity<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> hir::ImplPolarity {
1761 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1762 match tcx.hir().expect_item_by_hir_id(hir_id).node {
1763 hir::ItemKind::Impl(_, polarity, ..) => polarity,
1764 ref item => bug!("impl_polarity: {:?} not an impl", item),
1768 // Is it marked with ?Sized
1769 fn is_unsized<'gcx: 'tcx, 'tcx>(
1770 astconv: &dyn AstConv<'gcx, 'tcx>,
1771 ast_bounds: &[hir::GenericBound],
1774 let tcx = astconv.tcx();
1776 // Try to find an unbound in bounds.
1777 let mut unbound = None;
1778 for ab in ast_bounds {
1779 if let &hir::GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = ab {
1780 if unbound.is_none() {
1781 unbound = Some(ptr.trait_ref.clone());
1787 "type parameter has more than one relaxed default \
1788 bound, only one is supported"
1794 let kind_id = tcx.lang_items().require(SizedTraitLangItem);
1797 // FIXME(#8559) currently requires the unbound to be built-in.
1798 if let Ok(kind_id) = kind_id {
1799 if tpb.path.res != Res::Def(DefKind::Trait, kind_id) {
1802 "default bound relaxed for a type parameter, but \
1803 this does nothing because the given bound is not \
1804 a default. Only `?Sized` is supported",
1809 _ if kind_id.is_ok() => {
1812 // No lang item for Sized, so we can't add it as a bound.
1819 /// Returns the early-bound lifetimes declared in this generics
1820 /// listing. For anything other than fns/methods, this is just all
1821 /// the lifetimes that are declared. For fns or methods, we have to
1822 /// screen out those that do not appear in any where-clauses etc using
1823 /// `resolve_lifetime::early_bound_lifetimes`.
1824 fn early_bound_lifetimes_from_generics<'a, 'tcx>(
1825 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1826 generics: &'a hir::Generics,
1827 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {
1831 .filter(move |param| match param.kind {
1832 GenericParamKind::Lifetime { .. } => {
1833 !tcx.is_late_bound(param.hir_id)
1839 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1840 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1841 /// inferred constraints concerning which regions outlive other regions.
1842 fn predicates_defined_on<'a, 'tcx>(
1843 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1845 ) -> Lrc<ty::GenericPredicates<'tcx>> {
1846 debug!("predicates_defined_on({:?})", def_id);
1847 let mut result = tcx.explicit_predicates_of(def_id);
1849 "predicates_defined_on: explicit_predicates_of({:?}) = {:?}",
1853 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1854 if !inferred_outlives.is_empty() {
1855 let span = tcx.def_span(def_id);
1857 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1861 Lrc::make_mut(&mut result)
1863 .extend(inferred_outlives.iter().map(|&p| (p, span)));
1865 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1869 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1870 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1871 /// `Self: Trait` predicates for traits.
1872 fn predicates_of<'a, 'tcx>(
1873 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1875 ) -> Lrc<ty::GenericPredicates<'tcx>> {
1876 let mut result = tcx.predicates_defined_on(def_id);
1878 if tcx.is_trait(def_id) {
1879 // For traits, add `Self: Trait` predicate. This is
1880 // not part of the predicates that a user writes, but it
1881 // is something that one must prove in order to invoke a
1882 // method or project an associated type.
1884 // In the chalk setup, this predicate is not part of the
1885 // "predicates" for a trait item. But it is useful in
1886 // rustc because if you directly (e.g.) invoke a trait
1887 // method like `Trait::method(...)`, you must naturally
1888 // prove that the trait applies to the types that were
1889 // used, and adding the predicate into this list ensures
1890 // that this is done.
1891 let span = tcx.def_span(def_id);
1892 Lrc::make_mut(&mut result)
1894 .push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span));
1896 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1900 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1901 /// N.B., this does not include any implied/inferred constraints.
1902 fn explicit_predicates_of<'a, 'tcx>(
1903 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1905 ) -> Lrc<ty::GenericPredicates<'tcx>> {
1907 use rustc_data_structures::fx::FxHashSet;
1909 debug!("explicit_predicates_of(def_id={:?})", def_id);
1911 /// A data structure with unique elements, which preserves order of insertion.
1912 /// Preserving the order of insertion is important here so as not to break
1913 /// compile-fail UI tests.
1914 struct UniquePredicates<'tcx> {
1915 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1916 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1919 impl<'tcx> UniquePredicates<'tcx> {
1923 uniques: FxHashSet::default(),
1927 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
1928 if self.uniques.insert(value) {
1929 self.predicates.push(value);
1933 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
1940 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1941 Some(hir_id) => hir_id,
1942 None => return tcx.predicates_of(def_id),
1944 let node = tcx.hir().get_by_hir_id(hir_id);
1946 let mut is_trait = None;
1947 let mut is_default_impl_trait = None;
1949 let icx = ItemCtxt::new(tcx, def_id);
1950 let no_generics = hir::Generics::empty();
1951 let empty_trait_items = HirVec::new();
1953 let mut predicates = UniquePredicates::new();
1955 let ast_generics = match node {
1956 Node::TraitItem(item) => &item.generics,
1958 Node::ImplItem(item) => match item.node {
1959 ImplItemKind::Existential(ref bounds) => {
1960 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1961 let opaque_ty = tcx.mk_opaque(def_id, substs);
1963 // Collect the bounds, i.e., the `A+B+'c` in `impl A+B+'c`.
1964 let bounds = compute_bounds(
1968 SizedByDefault::Yes,
1969 tcx.def_span(def_id),
1972 predicates.extend(bounds.predicates(tcx, opaque_ty));
1975 _ => &item.generics,
1978 Node::Item(item) => {
1980 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
1981 if defaultness.is_default() {
1982 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1986 ItemKind::Fn(.., ref generics, _)
1987 | ItemKind::Ty(_, ref generics)
1988 | ItemKind::Enum(_, ref generics)
1989 | ItemKind::Struct(_, ref generics)
1990 | ItemKind::Union(_, ref generics) => generics,
1992 ItemKind::Trait(_, _, ref generics, .., ref items) => {
1993 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
1996 ItemKind::TraitAlias(ref generics, _) => {
1997 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &empty_trait_items));
2000 ItemKind::Existential(ExistTy {
2006 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2007 let opaque_ty = tcx.mk_opaque(def_id, substs);
2009 // Collect the bounds, i.e., the `A+B+'c` in `impl A+B+'c`.
2010 let bounds = compute_bounds(
2014 SizedByDefault::Yes,
2015 tcx.def_span(def_id),
2018 if impl_trait_fn.is_some() {
2020 return Lrc::new(ty::GenericPredicates {
2022 predicates: bounds.predicates(tcx, opaque_ty),
2025 // named existential types
2026 predicates.extend(bounds.predicates(tcx, opaque_ty));
2035 Node::ForeignItem(item) => match item.node {
2036 ForeignItemKind::Static(..) => &no_generics,
2037 ForeignItemKind::Fn(_, _, ref generics) => generics,
2038 ForeignItemKind::Type => &no_generics,
2044 let generics = tcx.generics_of(def_id);
2045 let parent_count = generics.parent_count as u32;
2046 let has_own_self = generics.has_self && parent_count == 0;
2048 // Below we'll consider the bounds on the type parameters (including `Self`)
2049 // and the explicit where-clauses, but to get the full set of predicates
2050 // on a trait we need to add in the supertrait bounds and bounds found on
2051 // associated types.
2052 if let Some((_trait_ref, _)) = is_trait {
2053 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2056 // In default impls, we can assume that the self type implements
2057 // the trait. So in:
2059 // default impl Foo for Bar { .. }
2061 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2062 // (see below). Recall that a default impl is not itself an impl, but rather a
2063 // set of defaults that can be incorporated into another impl.
2064 if let Some(trait_ref) = is_default_impl_trait {
2065 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2068 // Collect the region predicates that were declared inline as
2069 // well. In the case of parameters declared on a fn or method, we
2070 // have to be careful to only iterate over early-bound regions.
2071 let mut index = parent_count + has_own_self as u32;
2072 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2073 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2074 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
2076 name: param.name.ident().as_interned_str(),
2081 GenericParamKind::Lifetime { .. } => {
2082 param.bounds.iter().for_each(|bound| match bound {
2083 hir::GenericBound::Outlives(lt) => {
2084 let bound = AstConv::ast_region_to_region(&icx, <, None);
2085 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2086 predicates.push((outlives.to_predicate(), lt.span));
2095 // Collect the predicates that were written inline by the user on each
2096 // type parameter (e.g., `<T:Foo>`).
2097 for param in &ast_generics.params {
2098 if let GenericParamKind::Type { .. } = param.kind {
2099 let name = param.name.ident().as_interned_str();
2100 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2103 let sized = SizedByDefault::Yes;
2104 let bounds = compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2105 predicates.extend(bounds.predicates(tcx, param_ty));
2109 // Add in the bounds that appear in the where-clause
2110 let where_clause = &ast_generics.where_clause;
2111 for predicate in &where_clause.predicates {
2113 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2114 let ty = icx.to_ty(&bound_pred.bounded_ty);
2116 // Keep the type around in a dummy predicate, in case of no bounds.
2117 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2118 // is still checked for WF.
2119 if bound_pred.bounds.is_empty() {
2120 if let ty::Param(_) = ty.sty {
2121 // This is a `where T:`, which can be in the HIR from the
2122 // transformation that moves `?Sized` to `T`'s declaration.
2123 // We can skip the predicate because type parameters are
2124 // trivially WF, but also we *should*, to avoid exposing
2125 // users who never wrote `where Type:,` themselves, to
2126 // compiler/tooling bugs from not handling WF predicates.
2128 let span = bound_pred.bounded_ty.span;
2129 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2131 (ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
2136 for bound in bound_pred.bounds.iter() {
2138 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2139 let mut projections = Vec::new();
2141 let (trait_ref, _) = AstConv::instantiate_poly_trait_ref(
2149 iter::once((trait_ref.to_predicate(), poly_trait_ref.span)).chain(
2150 projections.iter().map(|&(p, span)| (p.to_predicate(), span)
2154 &hir::GenericBound::Outlives(ref lifetime) => {
2155 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2156 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2157 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2163 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2164 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2165 predicates.extend(region_pred.bounds.iter().map(|bound| {
2166 let (r2, span) = match bound {
2167 hir::GenericBound::Outlives(lt) => {
2168 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2172 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2174 (ty::Predicate::RegionOutlives(pred), span)
2178 &hir::WherePredicate::EqPredicate(..) => {
2184 // Add predicates from associated type bounds.
2185 if let Some((self_trait_ref, trait_items)) = is_trait {
2186 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2187 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2188 let bounds = match trait_item.node {
2189 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2190 _ => return vec![].into_iter()
2194 tcx.mk_projection(tcx.hir().local_def_id_from_hir_id(trait_item.hir_id),
2195 self_trait_ref.substs);
2197 let bounds = compute_bounds(
2198 &ItemCtxt::new(tcx, def_id),
2201 SizedByDefault::Yes,
2205 bounds.predicates(tcx, assoc_ty).into_iter()
2209 let mut predicates = predicates.predicates;
2211 // Subtle: before we store the predicates into the tcx, we
2212 // sort them so that predicates like `T: Foo<Item=U>` come
2213 // before uses of `U`. This avoids false ambiguity errors
2214 // in trait checking. See `setup_constraining_predicates`
2216 if let Node::Item(&Item {
2217 node: ItemKind::Impl(..),
2221 let self_ty = tcx.type_of(def_id);
2222 let trait_ref = tcx.impl_trait_ref(def_id);
2223 cgp::setup_constraining_predicates(
2227 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2231 let result = Lrc::new(ty::GenericPredicates {
2232 parent: generics.parent,
2235 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2239 pub enum SizedByDefault {
2244 /// Translate the AST's notion of ty param bounds (which are an enum consisting of a newtyped `Ty`
2245 /// or a region) to ty's notion of ty param bounds, which can either be user-defined traits, or the
2246 /// built-in trait `Send`.
2247 pub fn compute_bounds<'gcx: 'tcx, 'tcx>(
2248 astconv: &dyn AstConv<'gcx, 'tcx>,
2250 ast_bounds: &[hir::GenericBound],
2251 sized_by_default: SizedByDefault,
2254 let mut region_bounds = Vec::new();
2255 let mut trait_bounds = Vec::new();
2257 for ast_bound in ast_bounds {
2259 hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::None) => trait_bounds.push(b),
2260 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {}
2261 hir::GenericBound::Outlives(ref l) => region_bounds.push(l),
2265 let mut projection_bounds = Vec::new();
2267 let mut trait_bounds: Vec<_> = trait_bounds.iter().map(|&bound| {
2268 let (poly_trait_ref, _) = astconv.instantiate_poly_trait_ref(
2271 &mut projection_bounds,
2273 (poly_trait_ref, bound.span)
2276 let region_bounds = region_bounds
2278 .map(|r| (astconv.ast_region_to_region(r, None), r.span))
2281 trait_bounds.sort_by_key(|(t, _)| t.def_id());
2283 let implicitly_sized = if let SizedByDefault::Yes = sized_by_default {
2284 if !is_unsized(astconv, ast_bounds, span) {
2301 /// Converts a specific `GenericBound` from the AST into a set of
2302 /// predicates that apply to the self type. A vector is returned
2303 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2304 /// predicates) to one (`T: Foo`) to many (`T: Bar<X=i32>` adds `T: Bar`
2305 /// and `<T as Bar>::X == i32`).
2306 fn predicates_from_bound<'tcx>(
2307 astconv: &dyn AstConv<'tcx, 'tcx>,
2309 bound: &hir::GenericBound,
2310 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2312 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2313 let mut projections = Vec::new();
2314 let (pred, _) = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut projections);
2315 iter::once((pred.to_predicate(), tr.span)).chain(
2318 .map(|(p, span)| (p.to_predicate(), span))
2321 hir::GenericBound::Outlives(ref lifetime) => {
2322 let region = astconv.ast_region_to_region(lifetime, None);
2323 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2324 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2326 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2330 fn compute_sig_of_foreign_fn_decl<'a, 'tcx>(
2331 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2335 ) -> ty::PolyFnSig<'tcx> {
2336 let unsafety = if abi == abi::Abi::RustIntrinsic {
2337 intrisic_operation_unsafety(&*tcx.item_name(def_id).as_str())
2339 hir::Unsafety::Unsafe
2341 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2343 // feature gate SIMD types in FFI, since I (huonw) am not sure the
2344 // ABIs are handled at all correctly.
2345 if abi != abi::Abi::RustIntrinsic
2346 && abi != abi::Abi::PlatformIntrinsic
2347 && !tcx.features().simd_ffi
2349 let check = |ast_ty: &hir::Ty, ty: Ty<'_>| {
2355 "use of SIMD type `{}` in FFI is highly experimental and \
2356 may result in invalid code",
2357 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2360 .help("add #![feature(simd_ffi)] to the crate attributes to enable")
2364 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2367 if let hir::Return(ref ty) = decl.output {
2368 check(&ty, *fty.output().skip_binder())
2375 fn is_foreign_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
2376 match tcx.hir().get_if_local(def_id) {
2377 Some(Node::ForeignItem(..)) => true,
2379 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2383 fn static_mutability<'a, 'tcx>(
2384 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2386 ) -> Option<hir::Mutability> {
2387 match tcx.hir().get_if_local(def_id) {
2388 Some(Node::Item(&hir::Item {
2389 node: hir::ItemKind::Static(_, mutbl, _), ..
2391 Some(Node::ForeignItem( &hir::ForeignItem {
2392 node: hir::ForeignItemKind::Static(_, mutbl), ..
2395 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2399 fn from_target_feature(
2400 tcx: TyCtxt<'_, '_, '_>,
2402 attr: &ast::Attribute,
2403 whitelist: &FxHashMap<String, Option<Symbol>>,
2404 target_features: &mut Vec<Symbol>,
2406 let list = match attr.meta_item_list() {
2410 let rust_features = tcx.features();
2412 // Only `enable = ...` is accepted in the meta item list
2413 if !item.check_name(sym::enable) {
2414 let msg = "#[target_feature(..)] only accepts sub-keys of `enable` \
2416 tcx.sess.span_err(item.span(), &msg);
2420 // Must be of the form `enable = "..."` ( a string)
2421 let value = match item.value_str() {
2422 Some(value) => value,
2424 let msg = "#[target_feature] attribute must be of the form \
2425 #[target_feature(enable = \"..\")]";
2426 tcx.sess.span_err(item.span(), &msg);
2431 // We allow comma separation to enable multiple features
2432 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2433 // Only allow whitelisted features per platform
2434 let feature_gate = match whitelist.get(feature) {
2438 "the feature named `{}` is not valid for \
2442 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2444 if feature.starts_with("+") {
2445 let valid = whitelist.contains_key(&feature[1..]);
2447 err.help("consider removing the leading `+` in the feature name");
2455 // Only allow features whose feature gates have been enabled
2456 let allowed = match feature_gate.as_ref().map(|s| *s) {
2457 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2458 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2459 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2460 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2461 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2462 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2463 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2464 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2465 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2466 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2467 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2468 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2469 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2470 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2471 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2472 Some(name) => bug!("unknown target feature gate {}", name),
2475 if !allowed && id.is_local() {
2476 feature_gate::emit_feature_err(
2477 &tcx.sess.parse_sess,
2478 feature_gate.unwrap(),
2480 feature_gate::GateIssue::Language,
2481 &format!("the target feature `{}` is currently unstable", feature),
2484 Some(Symbol::intern(feature))
2489 fn linkage_by_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId, name: &str) -> Linkage {
2490 use rustc::mir::mono::Linkage::*;
2492 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2493 // applicable to variable declarations and may not really make sense for
2494 // Rust code in the first place but whitelist them anyway and trust that
2495 // the user knows what s/he's doing. Who knows, unanticipated use cases
2496 // may pop up in the future.
2498 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2499 // and don't have to be, LLVM treats them as no-ops.
2501 "appending" => Appending,
2502 "available_externally" => AvailableExternally,
2504 "extern_weak" => ExternalWeak,
2505 "external" => External,
2506 "internal" => Internal,
2507 "linkonce" => LinkOnceAny,
2508 "linkonce_odr" => LinkOnceODR,
2509 "private" => Private,
2511 "weak_odr" => WeakODR,
2513 let span = tcx.hir().span_if_local(def_id);
2514 if let Some(span) = span {
2515 tcx.sess.span_fatal(span, "invalid linkage specified")
2518 .fatal(&format!("invalid linkage specified: {}", name))
2524 fn codegen_fn_attrs<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: DefId) -> CodegenFnAttrs {
2525 let attrs = tcx.get_attrs(id);
2527 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2529 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2531 let mut inline_span = None;
2532 for attr in attrs.iter() {
2533 if attr.check_name(sym::cold) {
2534 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2535 } else if attr.check_name(sym::allocator) {
2536 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2537 } else if attr.check_name(sym::unwind) {
2538 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2539 } else if attr.check_name(sym::ffi_returns_twice) {
2540 if tcx.is_foreign_item(id) {
2541 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2543 // `#[ffi_returns_twice]` is only allowed `extern fn`s
2548 "`#[ffi_returns_twice]` may only be used on foreign functions"
2551 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2552 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2553 } else if attr.check_name(sym::naked) {
2554 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2555 } else if attr.check_name(sym::no_mangle) {
2556 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2557 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2558 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2559 } else if attr.check_name(sym::no_debug) {
2560 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2561 } else if attr.check_name(sym::used) {
2562 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2563 } else if attr.check_name(sym::thread_local) {
2564 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2565 } else if attr.check_name(sym::export_name) {
2566 if let Some(s) = attr.value_str() {
2567 if s.as_str().contains("\0") {
2568 // `#[export_name = ...]` will be converted to a null-terminated string,
2569 // so it may not contain any null characters.
2574 "`export_name` may not contain null characters"
2577 codegen_fn_attrs.export_name = Some(s);
2579 } else if attr.check_name(sym::target_feature) {
2580 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2581 let msg = "#[target_feature(..)] can only be applied to \
2583 tcx.sess.span_err(attr.span, msg);
2585 from_target_feature(
2590 &mut codegen_fn_attrs.target_features,
2592 } else if attr.check_name(sym::linkage) {
2593 if let Some(val) = attr.value_str() {
2594 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2596 } else if attr.check_name(sym::link_section) {
2597 if let Some(val) = attr.value_str() {
2598 if val.as_str().bytes().any(|b| b == 0) {
2600 "illegal null byte in link_section \
2604 tcx.sess.span_err(attr.span, &msg);
2606 codegen_fn_attrs.link_section = Some(val);
2609 } else if attr.check_name(sym::link_name) {
2610 codegen_fn_attrs.link_name = attr.value_str();
2614 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2615 if attr.path != sym::inline {
2618 match attr.meta().map(|i| i.node) {
2619 Some(MetaItemKind::Word) => {
2623 Some(MetaItemKind::List(ref items)) => {
2625 inline_span = Some(attr.span);
2626 if items.len() != 1 {
2628 tcx.sess.diagnostic(),
2631 "expected one argument"
2634 } else if list_contains_name(&items[..], sym::always) {
2636 } else if list_contains_name(&items[..], sym::never) {
2640 tcx.sess.diagnostic(),
2649 Some(MetaItemKind::NameValue(_)) => ia,
2654 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2655 if attr.path != sym::optimize {
2658 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2659 match attr.meta().map(|i| i.node) {
2660 Some(MetaItemKind::Word) => {
2661 err(attr.span, "expected one argument");
2664 Some(MetaItemKind::List(ref items)) => {
2666 inline_span = Some(attr.span);
2667 if items.len() != 1 {
2668 err(attr.span, "expected one argument");
2670 } else if list_contains_name(&items[..], sym::size) {
2672 } else if list_contains_name(&items[..], sym::speed) {
2675 err(items[0].span(), "invalid argument");
2679 Some(MetaItemKind::NameValue(_)) => ia,
2684 // If a function uses #[target_feature] it can't be inlined into general
2685 // purpose functions as they wouldn't have the right target features
2686 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2688 if codegen_fn_attrs.target_features.len() > 0 {
2689 if codegen_fn_attrs.inline == InlineAttr::Always {
2690 if let Some(span) = inline_span {
2693 "cannot use #[inline(always)] with \
2700 // Weak lang items have the same semantics as "std internal" symbols in the
2701 // sense that they're preserved through all our LTO passes and only
2702 // strippable by the linker.
2704 // Additionally weak lang items have predetermined symbol names.
2705 if tcx.is_weak_lang_item(id) {
2706 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2708 if let Some(name) = weak_lang_items::link_name(&attrs) {
2709 codegen_fn_attrs.export_name = Some(name);
2710 codegen_fn_attrs.link_name = Some(name);
2713 // Internal symbols to the standard library all have no_mangle semantics in
2714 // that they have defined symbol names present in the function name. This
2715 // also applies to weak symbols where they all have known symbol names.
2716 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2717 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;