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 astconv::{AstConv, Bounds};
18 use constrained_type_params as ctp;
20 use middle::lang_items::SizedTraitLangItem;
21 use middle::resolve_lifetime as rl;
22 use middle::weak_lang_items;
23 use rustc::mir::mono::Linkage;
24 use rustc::ty::query::Providers;
25 use rustc::ty::query::queries;
26 use rustc::ty::subst::Substs;
27 use rustc::ty::util::Discr;
28 use rustc::ty::util::IntTypeExt;
29 use rustc::ty::{self, AdtKind, ToPolyTraitRef, Ty, TyCtxt};
30 use rustc::ty::{ReprOptions, ToPredicate};
31 use rustc::util::captures::Captures;
32 use rustc::util::nodemap::FxHashMap;
33 use rustc_data_structures::sync::Lrc;
34 use rustc_target::spec::abi;
37 use syntax::ast::{Ident, MetaItemKind};
38 use syntax::attr::{InlineAttr, list_contains_name, mark_used};
39 use syntax::source_map::Spanned;
40 use syntax::feature_gate;
41 use syntax::symbol::{keywords, Symbol};
42 use syntax_pos::{Span, DUMMY_SP};
44 use rustc::hir::def::{CtorKind, Def};
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};
53 struct OnlySelfBounds(bool);
55 ///////////////////////////////////////////////////////////////////////////
58 pub fn collect_item_types<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
59 for &module in tcx.hir().krate().modules.keys() {
60 queries::collect_mod_item_types::ensure(tcx, tcx.hir().local_def_id(module));
64 fn collect_mod_item_types<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
65 tcx.hir().visit_item_likes_in_module(
67 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor()
71 pub fn provide(providers: &mut Providers) {
72 *providers = Providers {
76 predicates_defined_on,
77 explicit_predicates_of,
79 type_param_predicates,
87 collect_mod_item_types,
92 ///////////////////////////////////////////////////////////////////////////
94 /// Context specific to some particular item. This is what implements
95 /// AstConv. It has information about the predicates that are defined
96 /// on the trait. Unfortunately, this predicate information is
97 /// available in various different forms at various points in the
98 /// process. So we can't just store a pointer to e.g., the AST or the
99 /// parsed ty form, we have to be more flexible. To this end, the
100 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
101 /// `get_type_parameter_bounds` requests, drawing the information from
102 /// the AST (`hir::Generics`), recursively.
103 pub struct ItemCtxt<'a, 'tcx: 'a> {
104 tcx: TyCtxt<'a, 'tcx, 'tcx>,
108 ///////////////////////////////////////////////////////////////////////////
110 struct CollectItemTypesVisitor<'a, 'tcx: 'a> {
111 tcx: TyCtxt<'a, 'tcx, 'tcx>,
114 impl<'a, 'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'a, 'tcx> {
115 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
116 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
119 fn visit_item(&mut self, item: &'tcx hir::Item) {
120 convert_item(self.tcx, item.id);
121 intravisit::walk_item(self, item);
124 fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
125 for param in &generics.params {
127 hir::GenericParamKind::Lifetime { .. } => {}
128 hir::GenericParamKind::Type {
131 let def_id = self.tcx.hir().local_def_id(param.id);
132 self.tcx.type_of(def_id);
134 hir::GenericParamKind::Type { .. } => {}
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(expr.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.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.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_node_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(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_node_id = tcx.hir().as_local_node_id(item_def_id).unwrap();
279 let ast_generics = match tcx.hir().get(item_node_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_node_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 /// Find 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: ast::NodeId,
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.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: ast::NodeId,
382 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.node {
384 Def::SelfTy(Some(def_id), None) | Def::TyParam(def_id) => {
385 def_id == tcx.hir().local_def_id(param_id)
394 fn convert_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_id: ast::NodeId) {
395 let it = tcx.hir().expect_item(item_id);
396 debug!("convert: item {} with id {}", it.ident, it.id);
397 let def_id = tcx.hir().local_def_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(item.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(f.id);
445 tcx.generics_of(def_id);
447 tcx.predicates_of(def_id);
450 if !struct_def.is_struct() {
451 convert_variant_ctor(tcx, struct_def.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: ast::NodeId) {
477 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
478 let def_id = tcx.hir().local_def_id(trait_item.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: ast::NodeId) {
498 let def_id = tcx.hir().local_def_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: ast::NodeId) {
508 let def_id = tcx.hir().local_def_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(e.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(f.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 convert_variant_ctor(tcx, variant.node.data.id());
564 fn convert_variant<'a, 'tcx>(
565 tcx: TyCtxt<'a, 'tcx, 'tcx>,
568 discr: ty::VariantDiscr,
569 def: &hir::VariantData,
570 adt_kind: ty::AdtKind,
571 attribute_def_id: DefId
572 ) -> ty::VariantDef {
573 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
574 let node_id = tcx.hir().as_local_node_id(did).unwrap();
579 let fid = tcx.hir().local_def_id(f.id);
580 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
581 if let Some(prev_span) = dup_span {
586 "field `{}` is already declared",
588 ).span_label(f.span, "field already declared")
589 .span_label(prev_span, format!("`{}` first declared here", f.ident))
592 seen_fields.insert(f.ident.modern(), f.span);
598 vis: ty::Visibility::from_hir(&f.vis, node_id, tcx),
602 ty::VariantDef::new(tcx,
608 CtorKind::from_hir(def),
613 fn adt_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::AdtDef {
616 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
617 let item = match tcx.hir().get(node_id) {
618 Node::Item(item) => item,
622 let repr = ReprOptions::new(tcx, def_id);
623 let (kind, variants) = match item.node {
624 ItemKind::Enum(ref def, _) => {
625 let mut distance_from_explicit = 0;
631 let did = tcx.hir().local_def_id(v.node.data.id());
632 let discr = if let Some(ref e) = v.node.disr_expr {
633 distance_from_explicit = 0;
634 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.id))
636 ty::VariantDiscr::Relative(distance_from_explicit)
638 distance_from_explicit += 1;
640 convert_variant(tcx, did, v.node.ident, discr, &v.node.data, AdtKind::Enum,
646 ItemKind::Struct(ref def, _) => {
647 // Use separate constructor id for unit/tuple structs and reuse did for braced structs.
648 let ctor_id = if !def.is_struct() {
649 Some(tcx.hir().local_def_id(def.id()))
655 std::iter::once(convert_variant(
657 ctor_id.unwrap_or(def_id),
659 ty::VariantDiscr::Relative(0),
666 ItemKind::Union(ref def, _) => (
668 std::iter::once(convert_variant(
672 ty::VariantDiscr::Relative(0),
680 tcx.alloc_adt_def(def_id, kind, variants, repr)
683 /// Ensures that the super-predicates of the trait with def-id
684 /// trait_def_id are converted and stored. This also ensures that
685 /// the transitive super-predicates are converted;
686 fn super_predicates_of<'a, 'tcx>(
687 tcx: TyCtxt<'a, 'tcx, 'tcx>,
689 ) -> Lrc<ty::GenericPredicates<'tcx>> {
690 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
691 let trait_node_id = tcx.hir().as_local_node_id(trait_def_id).unwrap();
693 let item = match tcx.hir().get(trait_node_id) {
694 Node::Item(item) => item,
695 _ => bug!("trait_node_id {} is not an item", trait_node_id),
698 let (generics, bounds) = match item.node {
699 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
700 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
701 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
704 let icx = ItemCtxt::new(tcx, trait_def_id);
706 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo : Bar + Zed`.
707 let self_param_ty = tcx.mk_self_type();
708 let superbounds1 = compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
710 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
712 // Convert any explicit superbounds in the where clause,
713 // e.g., `trait Foo where Self : Bar`.
714 // In the case of trait aliases, however, we include all bounds in the where clause,
715 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
716 // as one of its "superpredicates".
717 let is_trait_alias = ty::is_trait_alias(tcx, trait_def_id);
718 let superbounds2 = icx.type_parameter_bounds_in_generics(
719 generics, item.id, self_param_ty, OnlySelfBounds(!is_trait_alias));
721 // Combine the two lists to form the complete set of superbounds:
722 let superbounds: Vec<_> = superbounds1.into_iter().chain(superbounds2).collect();
724 // Now require that immediate supertraits are converted,
725 // which will, in turn, reach indirect supertraits.
726 for &(pred, span) in &superbounds {
727 debug!("superbound: {:?}", pred);
728 if let ty::Predicate::Trait(bound) = pred {
729 tcx.at(span).super_predicates_of(bound.def_id());
733 Lrc::new(ty::GenericPredicates {
735 predicates: superbounds,
739 fn trait_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::TraitDef {
740 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
741 let item = tcx.hir().expect_item(node_id);
743 let (is_auto, unsafety) = match item.node {
744 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
745 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
746 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
749 let paren_sugar = tcx.has_attr(def_id, "rustc_paren_sugar");
750 if paren_sugar && !tcx.features().unboxed_closures {
751 let mut err = tcx.sess.struct_span_err(
753 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
754 which traits can use parenthetical notation",
758 "add `#![feature(unboxed_closures)]` to \
759 the crate attributes to use it"
764 let is_marker = tcx.has_attr(def_id, "marker");
765 let def_path_hash = tcx.def_path_hash(def_id);
766 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
767 tcx.alloc_trait_def(def)
770 fn has_late_bound_regions<'a, 'tcx>(
771 tcx: TyCtxt<'a, 'tcx, 'tcx>,
774 struct LateBoundRegionsDetector<'a, 'tcx: 'a> {
775 tcx: TyCtxt<'a, 'tcx, 'tcx>,
776 outer_index: ty::DebruijnIndex,
777 has_late_bound_regions: Option<Span>,
780 impl<'a, 'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'a, 'tcx> {
781 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
782 NestedVisitorMap::None
785 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
786 if self.has_late_bound_regions.is_some() {
790 hir::TyKind::BareFn(..) => {
791 self.outer_index.shift_in(1);
792 intravisit::walk_ty(self, ty);
793 self.outer_index.shift_out(1);
795 _ => intravisit::walk_ty(self, ty),
799 fn visit_poly_trait_ref(
801 tr: &'tcx hir::PolyTraitRef,
802 m: hir::TraitBoundModifier,
804 if self.has_late_bound_regions.is_some() {
807 self.outer_index.shift_in(1);
808 intravisit::walk_poly_trait_ref(self, tr, m);
809 self.outer_index.shift_out(1);
812 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
813 if self.has_late_bound_regions.is_some() {
817 let hir_id = self.tcx.hir().node_to_hir_id(lt.id);
818 match self.tcx.named_region(hir_id) {
819 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
820 Some(rl::Region::LateBound(debruijn, _, _))
821 | Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
822 Some(rl::Region::LateBound(..))
823 | Some(rl::Region::LateBoundAnon(..))
824 | Some(rl::Region::Free(..))
826 self.has_late_bound_regions = Some(lt.span);
832 fn has_late_bound_regions<'a, 'tcx>(
833 tcx: TyCtxt<'a, 'tcx, 'tcx>,
834 generics: &'tcx hir::Generics,
835 decl: &'tcx hir::FnDecl,
837 let mut visitor = LateBoundRegionsDetector {
839 outer_index: ty::INNERMOST,
840 has_late_bound_regions: None,
842 for param in &generics.params {
843 if let GenericParamKind::Lifetime { .. } = param.kind {
844 let hir_id = tcx.hir().node_to_hir_id(param.id);
845 if tcx.is_late_bound(hir_id) {
846 return Some(param.span);
850 visitor.visit_fn_decl(decl);
851 visitor.has_late_bound_regions
855 Node::TraitItem(item) => match item.node {
856 hir::TraitItemKind::Method(ref sig, _) => {
857 has_late_bound_regions(tcx, &item.generics, &sig.decl)
861 Node::ImplItem(item) => match item.node {
862 hir::ImplItemKind::Method(ref sig, _) => {
863 has_late_bound_regions(tcx, &item.generics, &sig.decl)
867 Node::ForeignItem(item) => match item.node {
868 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
869 has_late_bound_regions(tcx, generics, fn_decl)
873 Node::Item(item) => match item.node {
874 hir::ItemKind::Fn(ref fn_decl, .., ref generics, _) => {
875 has_late_bound_regions(tcx, generics, fn_decl)
883 fn generics_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::Generics {
886 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
888 let node = tcx.hir().get(node_id);
889 let parent_def_id = match node {
890 Node::ImplItem(_) | Node::TraitItem(_) | Node::Variant(_)
891 | Node::StructCtor(_) | Node::Field(_) => {
892 let parent_id = tcx.hir().get_parent(node_id);
893 Some(tcx.hir().local_def_id(parent_id))
895 Node::Expr(&hir::Expr {
896 node: hir::ExprKind::Closure(..),
898 }) => Some(tcx.closure_base_def_id(def_id)),
899 Node::Item(item) => match item.node {
900 ItemKind::Existential(hir::ExistTy { impl_trait_fn, .. }) => impl_trait_fn,
906 let mut opt_self = None;
907 let mut allow_defaults = false;
909 let no_generics = hir::Generics::empty();
910 let ast_generics = match node {
911 Node::TraitItem(item) => &item.generics,
913 Node::ImplItem(item) => &item.generics,
915 Node::Item(item) => {
917 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
921 ItemKind::Ty(_, ref generics)
922 | ItemKind::Enum(_, ref generics)
923 | ItemKind::Struct(_, ref generics)
924 | ItemKind::Existential(hir::ExistTy { ref generics, .. })
925 | ItemKind::Union(_, ref generics) => {
926 allow_defaults = true;
930 ItemKind::Trait(_, _, ref generics, ..)
931 | ItemKind::TraitAlias(ref generics, ..) => {
932 // Add in the self type parameter.
934 // Something of a hack: use the node id for the trait, also as
935 // the node id for the Self type parameter.
936 let param_id = item.id;
938 opt_self = Some(ty::GenericParamDef {
940 name: keywords::SelfUpper.name().as_interned_str(),
941 def_id: tcx.hir().local_def_id(param_id),
942 pure_wrt_drop: false,
943 kind: ty::GenericParamDefKind::Type {
945 object_lifetime_default: rl::Set1::Empty,
950 allow_defaults = true;
958 Node::ForeignItem(item) => match item.node {
959 ForeignItemKind::Static(..) => &no_generics,
960 ForeignItemKind::Fn(_, _, ref generics) => generics,
961 ForeignItemKind::Type => &no_generics,
967 let has_self = opt_self.is_some();
968 let mut parent_has_self = false;
969 let mut own_start = has_self as u32;
970 let parent_count = parent_def_id.map_or(0, |def_id| {
971 let generics = tcx.generics_of(def_id);
972 assert_eq!(has_self, false);
973 parent_has_self = generics.has_self;
974 own_start = generics.count() as u32;
975 generics.parent_count + generics.params.len()
978 let mut params: Vec<_> = opt_self.into_iter().collect();
980 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
984 .map(|(i, param)| ty::GenericParamDef {
985 name: param.name.ident().as_interned_str(),
986 index: own_start + i as u32,
987 def_id: tcx.hir().local_def_id(param.id),
988 pure_wrt_drop: param.pure_wrt_drop,
989 kind: ty::GenericParamDefKind::Lifetime,
993 let hir_id = tcx.hir().node_to_hir_id(node_id);
994 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
996 // Now create the real type parameters.
997 let type_start = own_start - has_self as u32 + params.len() as u32;
1003 .filter_map(|param| match param.kind {
1004 GenericParamKind::Type {
1009 if param.name.ident().name == keywords::SelfUpper.name() {
1012 "`Self` should not be the name of a regular parameter"
1016 if !allow_defaults && default.is_some() {
1017 if !tcx.features().default_type_parameter_fallback {
1019 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1023 "defaults for type parameters are only allowed in \
1024 `struct`, `enum`, `type`, or `trait` definitions."
1030 let ty_param = ty::GenericParamDef {
1031 index: type_start + i as u32,
1032 name: param.name.ident().as_interned_str(),
1033 def_id: tcx.hir().local_def_id(param.id),
1034 pure_wrt_drop: param.pure_wrt_drop,
1035 kind: ty::GenericParamDefKind::Type {
1036 has_default: default.is_some(),
1037 object_lifetime_default: object_lifetime_defaults
1039 .map_or(rl::Set1::Empty, |o| o[i]),
1050 // provide junk type parameter defs - the only place that
1051 // cares about anything but the length is instantiation,
1052 // and we don't do that for closures.
1053 if let Node::Expr(&hir::Expr {
1054 node: hir::ExprKind::Closure(.., gen),
1058 let dummy_args = if gen.is_some() {
1059 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1061 &["<closure_kind>", "<closure_signature>"][..]
1068 .map(|(i, &arg)| ty::GenericParamDef {
1069 index: type_start + i as u32,
1070 name: Symbol::intern(arg).as_interned_str(),
1072 pure_wrt_drop: false,
1073 kind: ty::GenericParamDefKind::Type {
1075 object_lifetime_default: rl::Set1::Empty,
1081 tcx.with_freevars(node_id, |fv| {
1082 params.extend(fv.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1083 ty::GenericParamDef {
1084 index: type_start + i,
1085 name: Symbol::intern("<upvar>").as_interned_str(),
1087 pure_wrt_drop: false,
1088 kind: ty::GenericParamDefKind::Type {
1090 object_lifetime_default: rl::Set1::Empty,
1098 let param_def_id_to_index = params
1100 .map(|param| (param.def_id, param.index))
1103 tcx.alloc_generics(ty::Generics {
1104 parent: parent_def_id,
1107 param_def_id_to_index,
1108 has_self: has_self || parent_has_self,
1109 has_late_bound_regions: has_late_bound_regions(tcx, node),
1113 fn report_assoc_ty_on_inherent_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, span: Span) {
1118 "associated types are not allowed in inherent impls"
1122 fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
1125 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
1127 let icx = ItemCtxt::new(tcx, def_id);
1129 match tcx.hir().get(node_id) {
1130 Node::TraitItem(item) => match item.node {
1131 TraitItemKind::Method(..) => {
1132 let substs = Substs::identity_for_item(tcx, def_id);
1133 tcx.mk_fn_def(def_id, substs)
1135 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1136 TraitItemKind::Type(_, None) => {
1137 span_bug!(item.span, "associated type missing default");
1141 Node::ImplItem(item) => match item.node {
1142 ImplItemKind::Method(..) => {
1143 let substs = Substs::identity_for_item(tcx, def_id);
1144 tcx.mk_fn_def(def_id, substs)
1146 ImplItemKind::Const(ref ty, _) => icx.to_ty(ty),
1147 ImplItemKind::Existential(_) => {
1149 .impl_trait_ref(tcx.hir().get_parent_did(node_id))
1152 report_assoc_ty_on_inherent_impl(tcx, item.span);
1155 find_existential_constraints(tcx, def_id)
1157 ImplItemKind::Type(ref ty) => {
1159 .impl_trait_ref(tcx.hir().get_parent_did(node_id))
1162 report_assoc_ty_on_inherent_impl(tcx, item.span);
1169 Node::Item(item) => {
1171 ItemKind::Static(ref t, ..)
1172 | ItemKind::Const(ref t, _)
1173 | ItemKind::Ty(ref t, _)
1174 | ItemKind::Impl(.., ref t, _) => icx.to_ty(t),
1175 ItemKind::Fn(..) => {
1176 let substs = Substs::identity_for_item(tcx, def_id);
1177 tcx.mk_fn_def(def_id, substs)
1179 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1180 let def = tcx.adt_def(def_id);
1181 let substs = Substs::identity_for_item(tcx, def_id);
1182 tcx.mk_adt(def, substs)
1184 ItemKind::Existential(hir::ExistTy {
1185 impl_trait_fn: None,
1187 }) => find_existential_constraints(tcx, def_id),
1188 // existential types desugared from impl Trait
1189 ItemKind::Existential(hir::ExistTy {
1190 impl_trait_fn: Some(owner),
1193 tcx.typeck_tables_of(owner)
1194 .concrete_existential_types
1197 .unwrap_or_else(|| {
1198 // This can occur if some error in the
1199 // owner fn prevented us from populating
1200 // the `concrete_existential_types` table.
1201 tcx.sess.delay_span_bug(
1204 "owner {:?} has no existential type for {:?} in its tables",
1212 | ItemKind::TraitAlias(..)
1214 | ItemKind::ForeignMod(..)
1215 | ItemKind::GlobalAsm(..)
1216 | ItemKind::ExternCrate(..)
1217 | ItemKind::Use(..) => {
1220 "compute_type_of_item: unexpected item type: {:?}",
1227 Node::ForeignItem(foreign_item) => match foreign_item.node {
1228 ForeignItemKind::Fn(..) => {
1229 let substs = Substs::identity_for_item(tcx, def_id);
1230 tcx.mk_fn_def(def_id, substs)
1232 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1233 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1236 Node::StructCtor(&ref def)
1237 | Node::Variant(&Spanned {
1238 node: hir::VariantKind { data: ref def, .. },
1241 VariantData::Unit(..) | VariantData::Struct(..) => {
1242 tcx.type_of(tcx.hir().get_parent_did(node_id))
1244 VariantData::Tuple(..) => {
1245 let substs = Substs::identity_for_item(tcx, def_id);
1246 tcx.mk_fn_def(def_id, substs)
1250 Node::Field(field) => icx.to_ty(&field.ty),
1252 Node::Expr(&hir::Expr {
1253 node: hir::ExprKind::Closure(.., gen),
1257 let hir_id = tcx.hir().node_to_hir_id(node_id);
1258 return tcx.typeck_tables_of(def_id).node_id_to_type(hir_id);
1261 let substs = ty::ClosureSubsts {
1262 substs: Substs::identity_for_item(tcx, def_id),
1265 tcx.mk_closure(def_id, substs)
1268 Node::AnonConst(_) => match tcx.hir().get(tcx.hir().get_parent_node(node_id)) {
1270 node: hir::TyKind::Array(_, ref constant),
1273 | Node::Ty(&hir::Ty {
1274 node: hir::TyKind::Typeof(ref constant),
1277 | Node::Expr(&hir::Expr {
1278 node: ExprKind::Repeat(_, ref constant),
1280 }) if constant.id == node_id =>
1285 Node::Variant(&Spanned {
1288 disr_expr: Some(ref e),
1292 }) if e.id == node_id =>
1294 tcx.adt_def(tcx.hir().get_parent_did(node_id))
1301 bug!("unexpected const parent in type_of_def_id(): {:?}", x);
1305 Node::GenericParam(param) => match param.kind {
1306 hir::GenericParamKind::Type {
1307 default: Some(ref ty),
1310 _ => bug!("unexpected non-type NodeGenericParam"),
1314 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1319 fn find_existential_constraints<'a, 'tcx>(
1320 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1325 struct ConstraintLocator<'a, 'tcx: 'a> {
1326 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1328 found: Option<(Span, ty::Ty<'tcx>)>,
1331 impl<'a, 'tcx> ConstraintLocator<'a, 'tcx> {
1332 fn check(&mut self, def_id: DefId) {
1333 trace!("checking {:?}", def_id);
1334 // don't try to check items that cannot possibly constrain the type
1335 if !self.tcx.has_typeck_tables(def_id) {
1336 trace!("no typeck tables for {:?}", def_id);
1341 .typeck_tables_of(def_id)
1342 .concrete_existential_types
1345 if let Some(ty) = ty {
1346 // FIXME(oli-obk): trace the actual span from inference to improve errors
1347 let span = self.tcx.def_span(def_id);
1348 if let Some((prev_span, prev_ty)) = self.found {
1350 // found different concrete types for the existential type
1351 let mut err = self.tcx.sess.struct_span_err(
1353 "defining existential type use differs from previous",
1355 err.span_note(prev_span, "previous use here");
1359 self.found = Some((span, ty));
1365 impl<'a, 'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'a, 'tcx> {
1366 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1367 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1369 fn visit_item(&mut self, it: &'tcx Item) {
1370 let def_id = self.tcx.hir().local_def_id(it.id);
1371 // the existential type itself or its children are not within its reveal scope
1372 if def_id != self.def_id {
1374 intravisit::walk_item(self, it);
1377 fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
1378 let def_id = self.tcx.hir().local_def_id(it.id);
1379 // the existential type itself or its children are not within its reveal scope
1380 if def_id != self.def_id {
1382 intravisit::walk_impl_item(self, it);
1385 fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
1386 let def_id = self.tcx.hir().local_def_id(it.id);
1388 intravisit::walk_trait_item(self, it);
1392 let mut locator = ConstraintLocator {
1397 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
1398 let parent = tcx.hir().get_parent(node_id);
1400 trace!("parent_id: {:?}", parent);
1402 if parent == ast::CRATE_NODE_ID {
1403 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1405 trace!("parent: {:?}", tcx.hir().get(parent));
1406 match tcx.hir().get(parent) {
1407 Node::Item(ref it) => intravisit::walk_item(&mut locator, it),
1408 Node::ImplItem(ref it) => intravisit::walk_impl_item(&mut locator, it),
1409 Node::TraitItem(ref it) => intravisit::walk_trait_item(&mut locator, it),
1411 "{:?} is not a valid parent of an existential type item",
1417 match locator.found {
1418 Some((_, ty)) => ty,
1420 let span = tcx.def_span(def_id);
1421 tcx.sess.span_err(span, "could not find defining uses");
1427 fn fn_sig<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ty::PolyFnSig<'tcx> {
1429 use rustc::hir::Node::*;
1431 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
1433 let icx = ItemCtxt::new(tcx, def_id);
1435 match tcx.hir().get(node_id) {
1436 TraitItem(hir::TraitItem {
1437 node: TraitItemKind::Method(sig, _),
1440 | ImplItem(hir::ImplItem {
1441 node: ImplItemKind::Method(sig, _),
1443 }) => AstConv::ty_of_fn(&icx, sig.header.unsafety, sig.header.abi, &sig.decl),
1446 node: ItemKind::Fn(decl, header, _, _),
1448 }) => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl),
1450 ForeignItem(&hir::ForeignItem {
1451 node: ForeignItemKind::Fn(ref fn_decl, _, _),
1454 let abi = tcx.hir().get_foreign_abi(node_id);
1455 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1458 StructCtor(&VariantData::Tuple(ref fields, _))
1459 | Variant(&Spanned {
1462 data: VariantData::Tuple(ref fields, _),
1467 let ty = tcx.type_of(tcx.hir().get_parent_did(node_id));
1470 .map(|f| tcx.type_of(tcx.hir().local_def_id(f.id)));
1471 ty::Binder::bind(tcx.mk_fn_sig(
1475 hir::Unsafety::Normal,
1481 node: hir::ExprKind::Closure(..),
1484 // Closure signatures are not like other function
1485 // signatures and cannot be accessed through `fn_sig`. For
1486 // example, a closure signature excludes the `self`
1487 // argument. In any case they are embedded within the
1488 // closure type as part of the `ClosureSubsts`.
1491 // the signature of a closure, you should use the
1492 // `closure_sig` method on the `ClosureSubsts`:
1494 // closure_substs.closure_sig(def_id, tcx)
1496 // or, inside of an inference context, you can use
1498 // infcx.closure_sig(def_id, closure_substs)
1499 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1503 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1508 fn impl_trait_ref<'a, 'tcx>(
1509 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1511 ) -> Option<ty::TraitRef<'tcx>> {
1512 let icx = ItemCtxt::new(tcx, def_id);
1514 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
1515 match tcx.hir().expect_item(node_id).node {
1516 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1517 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1518 let selfty = tcx.type_of(def_id);
1519 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1526 fn impl_polarity<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> hir::ImplPolarity {
1527 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
1528 match tcx.hir().expect_item(node_id).node {
1529 hir::ItemKind::Impl(_, polarity, ..) => polarity,
1530 ref item => bug!("impl_polarity: {:?} not an impl", item),
1534 // Is it marked with ?Sized
1535 fn is_unsized<'gcx: 'tcx, 'tcx>(
1536 astconv: &dyn AstConv<'gcx, 'tcx>,
1537 ast_bounds: &[hir::GenericBound],
1540 let tcx = astconv.tcx();
1542 // Try to find an unbound in bounds.
1543 let mut unbound = None;
1544 for ab in ast_bounds {
1545 if let &hir::GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = ab {
1546 if unbound.is_none() {
1547 unbound = Some(ptr.trait_ref.clone());
1553 "type parameter has more than one relaxed default \
1554 bound, only one is supported"
1560 let kind_id = tcx.lang_items().require(SizedTraitLangItem);
1563 // FIXME(#8559) currently requires the unbound to be built-in.
1564 if let Ok(kind_id) = kind_id {
1565 if tpb.path.def != Def::Trait(kind_id) {
1568 "default bound relaxed for a type parameter, but \
1569 this does nothing because the given bound is not \
1570 a default. Only `?Sized` is supported",
1575 _ if kind_id.is_ok() => {
1578 // No lang item for Sized, so we can't add it as a bound.
1585 /// Returns the early-bound lifetimes declared in this generics
1586 /// listing. For anything other than fns/methods, this is just all
1587 /// the lifetimes that are declared. For fns or methods, we have to
1588 /// screen out those that do not appear in any where-clauses etc using
1589 /// `resolve_lifetime::early_bound_lifetimes`.
1590 fn early_bound_lifetimes_from_generics<'a, 'tcx>(
1591 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1592 generics: &'a hir::Generics,
1593 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {
1597 .filter(move |param| match param.kind {
1598 GenericParamKind::Lifetime { .. } => {
1599 let hir_id = tcx.hir().node_to_hir_id(param.id);
1600 !tcx.is_late_bound(hir_id)
1606 fn predicates_defined_on<'a, 'tcx>(
1607 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1609 ) -> Lrc<ty::GenericPredicates<'tcx>> {
1610 debug!("predicates_defined_on({:?})", def_id);
1611 let mut result = tcx.explicit_predicates_of(def_id);
1613 "predicates_defined_on: explicit_predicates_of({:?}) = {:?}",
1617 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1618 if !inferred_outlives.is_empty() {
1619 let span = tcx.def_span(def_id);
1621 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1625 Lrc::make_mut(&mut result)
1627 .extend(inferred_outlives.iter().map(|&p| (p, span)));
1629 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1633 fn predicates_of<'a, 'tcx>(
1634 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1636 ) -> Lrc<ty::GenericPredicates<'tcx>> {
1637 let mut result = tcx.predicates_defined_on(def_id);
1639 if tcx.is_trait(def_id) {
1640 // For traits, add `Self: Trait` predicate. This is
1641 // not part of the predicates that a user writes, but it
1642 // is something that one must prove in order to invoke a
1643 // method or project an associated type.
1645 // In the chalk setup, this predicate is not part of the
1646 // "predicates" for a trait item. But it is useful in
1647 // rustc because if you directly (e.g.) invoke a trait
1648 // method like `Trait::method(...)`, you must naturally
1649 // prove that the trait applies to the types that were
1650 // used, and adding the predicate into this list ensures
1651 // that this is done.
1652 let span = tcx.def_span(def_id);
1653 Lrc::make_mut(&mut result)
1655 .push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span));
1657 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1661 fn explicit_predicates_of<'a, 'tcx>(
1662 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1664 ) -> Lrc<ty::GenericPredicates<'tcx>> {
1666 use rustc_data_structures::fx::FxHashSet;
1668 debug!("explicit_predicates_of(def_id={:?})", def_id);
1670 /// A data structure with unique elements, which preserves order of insertion.
1671 /// Preserving the order of insertion is important here so as not to break
1672 /// compile-fail UI tests.
1673 struct UniquePredicates<'tcx> {
1674 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1675 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1678 impl<'tcx> UniquePredicates<'tcx> {
1682 uniques: FxHashSet::default(),
1686 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
1687 if self.uniques.insert(value) {
1688 self.predicates.push(value);
1692 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
1699 let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
1700 let node = tcx.hir().get(node_id);
1702 let mut is_trait = None;
1703 let mut is_default_impl_trait = None;
1705 let icx = ItemCtxt::new(tcx, def_id);
1706 let no_generics = hir::Generics::empty();
1707 let empty_trait_items = HirVec::new();
1709 let mut predicates = UniquePredicates::new();
1711 let ast_generics = match node {
1712 Node::TraitItem(item) => &item.generics,
1714 Node::ImplItem(item) => match item.node {
1715 ImplItemKind::Existential(ref bounds) => {
1716 let substs = Substs::identity_for_item(tcx, def_id);
1717 let opaque_ty = tcx.mk_opaque(def_id, substs);
1719 // Collect the bounds, i.e., the `A+B+'c` in `impl A+B+'c`.
1720 let bounds = compute_bounds(
1724 SizedByDefault::Yes,
1725 tcx.def_span(def_id),
1728 predicates.extend(bounds.predicates(tcx, opaque_ty));
1731 _ => &item.generics,
1734 Node::Item(item) => {
1736 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
1737 if defaultness.is_default() {
1738 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1742 ItemKind::Fn(.., ref generics, _)
1743 | ItemKind::Ty(_, ref generics)
1744 | ItemKind::Enum(_, ref generics)
1745 | ItemKind::Struct(_, ref generics)
1746 | ItemKind::Union(_, ref generics) => generics,
1748 ItemKind::Trait(_, _, ref generics, .., ref items) => {
1749 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
1752 ItemKind::TraitAlias(ref generics, _) => {
1753 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &empty_trait_items));
1756 ItemKind::Existential(ExistTy {
1761 let substs = Substs::identity_for_item(tcx, def_id);
1762 let opaque_ty = tcx.mk_opaque(def_id, substs);
1764 // Collect the bounds, i.e., the `A+B+'c` in `impl A+B+'c`.
1765 let bounds = compute_bounds(
1769 SizedByDefault::Yes,
1770 tcx.def_span(def_id),
1773 if impl_trait_fn.is_some() {
1775 return Lrc::new(ty::GenericPredicates {
1777 predicates: bounds.predicates(tcx, opaque_ty),
1780 // named existential types
1781 predicates.extend(bounds.predicates(tcx, opaque_ty));
1790 Node::ForeignItem(item) => match item.node {
1791 ForeignItemKind::Static(..) => &no_generics,
1792 ForeignItemKind::Fn(_, _, ref generics) => generics,
1793 ForeignItemKind::Type => &no_generics,
1799 let generics = tcx.generics_of(def_id);
1800 let parent_count = generics.parent_count as u32;
1801 let has_own_self = generics.has_self && parent_count == 0;
1803 // Below we'll consider the bounds on the type parameters (including `Self`)
1804 // and the explicit where-clauses, but to get the full set of predicates
1805 // on a trait we need to add in the supertrait bounds and bounds found on
1806 // associated types.
1807 if let Some((_trait_ref, _)) = is_trait {
1808 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
1811 // In default impls, we can assume that the self type implements
1812 // the trait. So in:
1814 // default impl Foo for Bar { .. }
1816 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
1817 // (see below). Recall that a default impl is not itself an impl, but rather a
1818 // set of defaults that can be incorporated into another impl.
1819 if let Some(trait_ref) = is_default_impl_trait {
1820 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
1823 // Collect the region predicates that were declared inline as
1824 // well. In the case of parameters declared on a fn or method, we
1825 // have to be careful to only iterate over early-bound regions.
1826 let mut index = parent_count + has_own_self as u32;
1827 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
1828 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
1829 def_id: tcx.hir().local_def_id(param.id),
1831 name: param.name.ident().as_interned_str(),
1836 GenericParamKind::Lifetime { .. } => {
1837 param.bounds.iter().for_each(|bound| match bound {
1838 hir::GenericBound::Outlives(lt) => {
1839 let bound = AstConv::ast_region_to_region(&icx, <, None);
1840 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
1841 predicates.push((outlives.to_predicate(), lt.span));
1850 // Collect the predicates that were written inline by the user on each
1851 // type parameter (e.g., `<T:Foo>`).
1852 for param in &ast_generics.params {
1853 if let GenericParamKind::Type { .. } = param.kind {
1854 let name = param.name.ident().as_interned_str();
1855 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
1858 let sized = SizedByDefault::Yes;
1859 let bounds = compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
1860 predicates.extend(bounds.predicates(tcx, param_ty));
1864 // Add in the bounds that appear in the where-clause
1865 let where_clause = &ast_generics.where_clause;
1866 for predicate in &where_clause.predicates {
1868 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
1869 let ty = icx.to_ty(&bound_pred.bounded_ty);
1871 // Keep the type around in a dummy predicate, in case of no bounds.
1872 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
1873 // is still checked for WF.
1874 if bound_pred.bounds.is_empty() {
1875 if let ty::Param(_) = ty.sty {
1876 // This is a `where T:`, which can be in the HIR from the
1877 // transformation that moves `?Sized` to `T`'s declaration.
1878 // We can skip the predicate because type parameters are
1879 // trivially WF, but also we *should*, to avoid exposing
1880 // users who never wrote `where Type:,` themselves, to
1881 // compiler/tooling bugs from not handling WF predicates.
1883 let span = bound_pred.bounded_ty.span;
1884 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
1886 (ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
1891 for bound in bound_pred.bounds.iter() {
1893 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
1894 let mut projections = Vec::new();
1896 let (trait_ref, _) = AstConv::instantiate_poly_trait_ref(
1904 iter::once((trait_ref.to_predicate(), poly_trait_ref.span)).chain(
1905 projections.iter().map(|&(p, span)| (p.to_predicate(), span)
1909 &hir::GenericBound::Outlives(ref lifetime) => {
1910 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
1911 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
1912 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
1918 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
1919 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
1920 predicates.extend(region_pred.bounds.iter().map(|bound| {
1921 let (r2, span) = match bound {
1922 hir::GenericBound::Outlives(lt) => {
1923 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
1927 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
1929 (ty::Predicate::RegionOutlives(pred), span)
1933 &hir::WherePredicate::EqPredicate(..) => {
1939 // Add predicates from associated type bounds.
1940 if let Some((self_trait_ref, trait_items)) = is_trait {
1941 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
1942 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
1943 let bounds = match trait_item.node {
1944 hir::TraitItemKind::Type(ref bounds, _) => bounds,
1945 _ => return vec![].into_iter()
1949 tcx.mk_projection(tcx.hir().local_def_id(trait_item.id), self_trait_ref.substs);
1951 let bounds = compute_bounds(
1952 &ItemCtxt::new(tcx, def_id),
1955 SizedByDefault::Yes,
1959 bounds.predicates(tcx, assoc_ty).into_iter()
1963 let mut predicates = predicates.predicates;
1965 // Subtle: before we store the predicates into the tcx, we
1966 // sort them so that predicates like `T: Foo<Item=U>` come
1967 // before uses of `U`. This avoids false ambiguity errors
1968 // in trait checking. See `setup_constraining_predicates`
1970 if let Node::Item(&Item {
1971 node: ItemKind::Impl(..),
1975 let self_ty = tcx.type_of(def_id);
1976 let trait_ref = tcx.impl_trait_ref(def_id);
1977 ctp::setup_constraining_predicates(
1981 &mut ctp::parameters_for_impl(self_ty, trait_ref),
1985 let result = Lrc::new(ty::GenericPredicates {
1986 parent: generics.parent,
1989 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
1993 pub enum SizedByDefault {
1998 /// Translate the AST's notion of ty param bounds (which are an enum consisting of a newtyped `Ty`
1999 /// or a region) to ty's notion of ty param bounds, which can either be user-defined traits, or the
2000 /// built-in trait `Send`.
2001 pub fn compute_bounds<'gcx: 'tcx, 'tcx>(
2002 astconv: &dyn AstConv<'gcx, 'tcx>,
2004 ast_bounds: &[hir::GenericBound],
2005 sized_by_default: SizedByDefault,
2008 let mut region_bounds = Vec::new();
2009 let mut trait_bounds = Vec::new();
2011 for ast_bound in ast_bounds {
2013 hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::None) => trait_bounds.push(b),
2014 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {}
2015 hir::GenericBound::Outlives(ref l) => region_bounds.push(l),
2019 let mut projection_bounds = Vec::new();
2021 let mut trait_bounds: Vec<_> = trait_bounds.iter().map(|&bound| {
2022 let (poly_trait_ref, _) = astconv.instantiate_poly_trait_ref(
2025 &mut projection_bounds,
2027 (poly_trait_ref, bound.span)
2030 let region_bounds = region_bounds
2032 .map(|r| (astconv.ast_region_to_region(r, None), r.span))
2035 trait_bounds.sort_by_key(|(t, _)| t.def_id());
2037 let implicitly_sized = if let SizedByDefault::Yes = sized_by_default {
2038 if !is_unsized(astconv, ast_bounds, span) {
2055 /// Converts a specific `GenericBound` from the AST into a set of
2056 /// predicates that apply to the self-type. A vector is returned
2057 /// because this can be anywhere from zero predicates (`T : ?Sized` adds no
2058 /// predicates) to one (`T : Foo`) to many (`T : Bar<X=i32>` adds `T : Bar`
2059 /// and `<T as Bar>::X == i32`).
2060 fn predicates_from_bound<'tcx>(
2061 astconv: &dyn AstConv<'tcx, 'tcx>,
2063 bound: &hir::GenericBound,
2064 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2066 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2067 let mut projections = Vec::new();
2068 let (pred, _) = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut projections);
2069 iter::once((pred.to_predicate(), tr.span)).chain(
2072 .map(|(p, span)| (p.to_predicate(), span))
2075 hir::GenericBound::Outlives(ref lifetime) => {
2076 let region = astconv.ast_region_to_region(lifetime, None);
2077 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2078 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2080 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2084 fn compute_sig_of_foreign_fn_decl<'a, 'tcx>(
2085 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2089 ) -> ty::PolyFnSig<'tcx> {
2090 let unsafety = if abi == abi::Abi::RustIntrinsic {
2091 match &*tcx.item_name(def_id).as_str() {
2092 "size_of" | "min_align_of" | "needs_drop" => hir::Unsafety::Normal,
2093 _ => hir::Unsafety::Unsafe,
2096 hir::Unsafety::Unsafe
2098 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2100 // feature gate SIMD types in FFI, since I (huonw) am not sure the
2101 // ABIs are handled at all correctly.
2102 if abi != abi::Abi::RustIntrinsic
2103 && abi != abi::Abi::PlatformIntrinsic
2104 && !tcx.features().simd_ffi
2106 let check = |ast_ty: &hir::Ty, ty: Ty| {
2112 "use of SIMD type `{}` in FFI is highly experimental and \
2113 may result in invalid code",
2114 tcx.hir().node_to_pretty_string(ast_ty.id)
2117 .help("add #![feature(simd_ffi)] to the crate attributes to enable")
2121 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2124 if let hir::Return(ref ty) = decl.output {
2125 check(&ty, *fty.output().skip_binder())
2132 fn is_foreign_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
2133 match tcx.hir().get_if_local(def_id) {
2134 Some(Node::ForeignItem(..)) => true,
2136 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2140 fn from_target_feature(
2143 attr: &ast::Attribute,
2144 whitelist: &FxHashMap<String, Option<String>>,
2145 target_features: &mut Vec<Symbol>,
2147 let list = match attr.meta_item_list() {
2150 let msg = "#[target_feature] attribute must be of the form \
2151 #[target_feature(..)]";
2152 tcx.sess.span_err(attr.span, &msg);
2156 let rust_features = tcx.features();
2158 // Only `enable = ...` is accepted in the meta item list
2159 if !item.check_name("enable") {
2160 let msg = "#[target_feature(..)] only accepts sub-keys of `enable` \
2162 tcx.sess.span_err(item.span, &msg);
2166 // Must be of the form `enable = "..."` ( a string)
2167 let value = match item.value_str() {
2168 Some(value) => value,
2170 let msg = "#[target_feature] attribute must be of the form \
2171 #[target_feature(enable = \"..\")]";
2172 tcx.sess.span_err(item.span, &msg);
2177 // We allow comma separation to enable multiple features
2178 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2179 // Only allow whitelisted features per platform
2180 let feature_gate = match whitelist.get(feature) {
2184 "the feature named `{}` is not valid for \
2188 let mut err = tcx.sess.struct_span_err(item.span, &msg);
2190 if feature.starts_with("+") {
2191 let valid = whitelist.contains_key(&feature[1..]);
2193 err.help("consider removing the leading `+` in the feature name");
2201 // Only allow features whose feature gates have been enabled
2202 let allowed = match feature_gate.as_ref().map(|s| &**s) {
2203 Some("arm_target_feature") => rust_features.arm_target_feature,
2204 Some("aarch64_target_feature") => rust_features.aarch64_target_feature,
2205 Some("hexagon_target_feature") => rust_features.hexagon_target_feature,
2206 Some("powerpc_target_feature") => rust_features.powerpc_target_feature,
2207 Some("mips_target_feature") => rust_features.mips_target_feature,
2208 Some("avx512_target_feature") => rust_features.avx512_target_feature,
2209 Some("mmx_target_feature") => rust_features.mmx_target_feature,
2210 Some("sse4a_target_feature") => rust_features.sse4a_target_feature,
2211 Some("tbm_target_feature") => rust_features.tbm_target_feature,
2212 Some("wasm_target_feature") => rust_features.wasm_target_feature,
2213 Some("cmpxchg16b_target_feature") => rust_features.cmpxchg16b_target_feature,
2214 Some("adx_target_feature") => rust_features.adx_target_feature,
2215 Some(name) => bug!("unknown target feature gate {}", name),
2218 if !allowed && id.is_local() {
2219 feature_gate::emit_feature_err(
2220 &tcx.sess.parse_sess,
2221 feature_gate.as_ref().unwrap(),
2223 feature_gate::GateIssue::Language,
2224 &format!("the target feature `{}` is currently unstable", feature),
2227 Some(Symbol::intern(feature))
2232 fn linkage_by_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId, name: &str) -> Linkage {
2233 use rustc::mir::mono::Linkage::*;
2235 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2236 // applicable to variable declarations and may not really make sense for
2237 // Rust code in the first place but whitelist them anyway and trust that
2238 // the user knows what s/he's doing. Who knows, unanticipated use cases
2239 // may pop up in the future.
2241 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2242 // and don't have to be, LLVM treats them as no-ops.
2244 "appending" => Appending,
2245 "available_externally" => AvailableExternally,
2247 "extern_weak" => ExternalWeak,
2248 "external" => External,
2249 "internal" => Internal,
2250 "linkonce" => LinkOnceAny,
2251 "linkonce_odr" => LinkOnceODR,
2252 "private" => Private,
2254 "weak_odr" => WeakODR,
2256 let span = tcx.hir().span_if_local(def_id);
2257 if let Some(span) = span {
2258 tcx.sess.span_fatal(span, "invalid linkage specified")
2261 .fatal(&format!("invalid linkage specified: {}", name))
2267 fn codegen_fn_attrs<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: DefId) -> CodegenFnAttrs {
2268 let attrs = tcx.get_attrs(id);
2270 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2272 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2274 let mut inline_span = None;
2275 for attr in attrs.iter() {
2276 if attr.check_name("cold") {
2277 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2278 } else if attr.check_name("allocator") {
2279 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2280 } else if attr.check_name("unwind") {
2281 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2282 } else if attr.check_name("rustc_allocator_nounwind") {
2283 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2284 } else if attr.check_name("naked") {
2285 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2286 } else if attr.check_name("no_mangle") {
2287 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2288 } else if attr.check_name("rustc_std_internal_symbol") {
2289 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2290 } else if attr.check_name("no_debug") {
2291 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2292 } else if attr.check_name("used") {
2293 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2294 } else if attr.check_name("thread_local") {
2295 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2296 } else if attr.check_name("inline") {
2297 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2298 if attr.path != "inline" {
2301 let meta = match attr.meta() {
2302 Some(meta) => meta.node,
2306 MetaItemKind::Word => {
2310 MetaItemKind::List(ref items) => {
2312 inline_span = Some(attr.span);
2313 if items.len() != 1 {
2315 tcx.sess.diagnostic(),
2318 "expected one argument"
2321 } else if list_contains_name(&items[..], "always") {
2323 } else if list_contains_name(&items[..], "never") {
2327 tcx.sess.diagnostic(),
2339 } else if attr.check_name("export_name") {
2340 if let Some(s) = attr.value_str() {
2341 if s.as_str().contains("\0") {
2342 // `#[export_name = ...]` will be converted to a null-terminated string,
2343 // so it may not contain any null characters.
2348 "`export_name` may not contain null characters"
2351 codegen_fn_attrs.export_name = Some(s);
2357 "`export_name` attribute has invalid format"
2358 ).span_label(attr.span, "did you mean #[export_name=\"*\"]?")
2361 } else if attr.check_name("target_feature") {
2362 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2363 let msg = "#[target_feature(..)] can only be applied to \
2365 tcx.sess.span_err(attr.span, msg);
2367 from_target_feature(
2372 &mut codegen_fn_attrs.target_features,
2374 } else if attr.check_name("linkage") {
2375 if let Some(val) = attr.value_str() {
2376 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2378 } else if attr.check_name("link_section") {
2379 if let Some(val) = attr.value_str() {
2380 if val.as_str().bytes().any(|b| b == 0) {
2382 "illegal null byte in link_section \
2386 tcx.sess.span_err(attr.span, &msg);
2388 codegen_fn_attrs.link_section = Some(val);
2391 } else if attr.check_name("link_name") {
2392 codegen_fn_attrs.link_name = attr.value_str();
2396 // If a function uses #[target_feature] it can't be inlined into general
2397 // purpose functions as they wouldn't have the right target features
2398 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2400 if codegen_fn_attrs.target_features.len() > 0 {
2401 if codegen_fn_attrs.inline == InlineAttr::Always {
2402 if let Some(span) = inline_span {
2405 "cannot use #[inline(always)] with \
2412 // Weak lang items have the same semantics as "std internal" symbols in the
2413 // sense that they're preserved through all our LTO passes and only
2414 // strippable by the linker.
2416 // Additionally weak lang items have predetermined symbol names.
2417 if tcx.is_weak_lang_item(id) {
2418 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2420 if let Some(name) = weak_lang_items::link_name(&attrs) {
2421 codegen_fn_attrs.export_name = Some(name);
2422 codegen_fn_attrs.link_name = Some(name);
2425 // Internal symbols to the standard library all have no_mangle semantics in
2426 // that they have defined symbol names present in the function name. This
2427 // also applies to weak symbols where they all have known symbol names.
2428 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2429 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;