1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *interprocedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::{AstConv, Bounds};
18 use crate::constrained_generic_params as cgp;
19 use crate::check::intrinsic::intrisic_operation_unsafety;
21 use crate::middle::lang_items::SizedTraitLangItem;
22 use crate::middle::resolve_lifetime as rl;
23 use crate::middle::weak_lang_items;
24 use rustc::mir::mono::Linkage;
25 use rustc::ty::query::Providers;
26 use rustc::ty::subst::{Subst, InternalSubsts};
27 use rustc::ty::util::Discr;
28 use rustc::ty::util::IntTypeExt;
29 use rustc::ty::subst::UnpackedKind;
30 use rustc::ty::{self, AdtKind, DefIdTree, ToPolyTraitRef, Ty, TyCtxt};
31 use rustc::ty::{ReprOptions, ToPredicate};
32 use rustc::util::captures::Captures;
33 use rustc::util::nodemap::FxHashMap;
34 use rustc_target::spec::abi;
37 use syntax::ast::{Ident, MetaItemKind};
38 use syntax::attr::{InlineAttr, OptimizeAttr, list_contains_name, mark_used};
39 use syntax::source_map::Spanned;
40 use syntax::feature_gate;
41 use syntax::symbol::{InternedString, kw, Symbol, sym};
42 use syntax_pos::{Span, DUMMY_SP};
44 use rustc::hir::def::{CtorKind, Res, DefKind};
46 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
47 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
48 use rustc::hir::GenericParamKind;
49 use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
51 use errors::Applicability;
55 struct OnlySelfBounds(bool);
57 ///////////////////////////////////////////////////////////////////////////
60 fn collect_mod_item_types<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
61 tcx.hir().visit_item_likes_in_module(
63 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor()
67 pub fn provide(providers: &mut Providers<'_>) {
68 *providers = Providers {
72 predicates_defined_on,
73 explicit_predicates_of,
75 type_param_predicates,
84 collect_mod_item_types,
89 ///////////////////////////////////////////////////////////////////////////
91 /// Context specific to some particular item. This is what implements
92 /// `AstConv`. It has information about the predicates that are defined
93 /// on the trait. Unfortunately, this predicate information is
94 /// available in various different forms at various points in the
95 /// process. So we can't just store a pointer to e.g., the AST or the
96 /// parsed ty form, we have to be more flexible. To this end, the
97 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
98 /// `get_type_parameter_bounds` requests, drawing the information from
99 /// the AST (`hir::Generics`), recursively.
100 pub struct ItemCtxt<'a, 'tcx: 'a> {
101 tcx: TyCtxt<'a, 'tcx, 'tcx>,
105 ///////////////////////////////////////////////////////////////////////////
107 struct CollectItemTypesVisitor<'a, 'tcx: 'a> {
108 tcx: TyCtxt<'a, 'tcx, 'tcx>,
111 impl<'a, 'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'a, 'tcx> {
112 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
113 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
116 fn visit_item(&mut self, item: &'tcx hir::Item) {
117 convert_item(self.tcx, item.hir_id);
118 intravisit::walk_item(self, item);
121 fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
122 for param in &generics.params {
124 hir::GenericParamKind::Lifetime { .. } => {}
125 hir::GenericParamKind::Type {
128 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
129 self.tcx.type_of(def_id);
131 hir::GenericParamKind::Type { .. } => {}
132 hir::GenericParamKind::Const { .. } => {
133 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
134 self.tcx.type_of(def_id);
138 intravisit::walk_generics(self, generics);
141 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
142 if let hir::ExprKind::Closure(..) = expr.node {
143 let def_id = self.tcx.hir().local_def_id_from_hir_id(expr.hir_id);
144 self.tcx.generics_of(def_id);
145 self.tcx.type_of(def_id);
147 intravisit::walk_expr(self, expr);
150 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
151 convert_trait_item(self.tcx, trait_item.hir_id);
152 intravisit::walk_trait_item(self, trait_item);
155 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
156 convert_impl_item(self.tcx, impl_item.hir_id);
157 intravisit::walk_impl_item(self, impl_item);
161 ///////////////////////////////////////////////////////////////////////////
162 // Utility types and common code for the above passes.
164 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
165 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_def_id: DefId) -> ItemCtxt<'a, 'tcx> {
166 ItemCtxt { tcx, item_def_id }
170 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
171 pub fn to_ty(&self, ast_ty: &hir::Ty) -> Ty<'tcx> {
172 AstConv::ast_ty_to_ty(self, ast_ty)
176 impl<'a, 'tcx> AstConv<'tcx, 'tcx> for ItemCtxt<'a, 'tcx> {
177 fn tcx<'b>(&'b self) -> TyCtxt<'b, 'tcx, 'tcx> {
181 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId)
182 -> &'tcx ty::GenericPredicates<'tcx> {
185 .type_param_predicates((self.item_def_id, def_id))
191 _def: Option<&ty::GenericParamDef>,
192 ) -> Option<ty::Region<'tcx>> {
196 fn ty_infer(&self, span: Span) -> Ty<'tcx> {
201 "the type placeholder `_` is not allowed within types on item signatures"
202 ).span_label(span, "not allowed in type signatures")
208 fn projected_ty_from_poly_trait_ref(
212 poly_trait_ref: ty::PolyTraitRef<'tcx>,
214 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
215 self.tcx().mk_projection(item_def_id, trait_ref.substs)
217 // no late-bound regions, we can just ignore the binder
222 "cannot extract an associated type from a higher-ranked trait bound \
229 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
230 // types in item signatures are not normalized, to avoid undue
235 fn set_tainted_by_errors(&self) {
236 // no obvious place to track this, just let it go
239 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
240 // no place to record types from signatures?
244 fn type_param_predicates<'a, 'tcx>(
245 tcx: TyCtxt<'a, 'tcx, 'tcx>,
246 (item_def_id, def_id): (DefId, DefId),
247 ) -> &'tcx ty::GenericPredicates<'tcx> {
250 // In the AST, bounds can derive from two places. Either
251 // written inline like `<T : Foo>` or in a where clause like
254 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
255 let param_owner = tcx.hir().ty_param_owner(param_id);
256 let param_owner_def_id = tcx.hir().local_def_id_from_hir_id(param_owner);
257 let generics = tcx.generics_of(param_owner_def_id);
258 let index = generics.param_def_id_to_index[&def_id];
259 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id).as_interned_str());
261 // Don't look for bounds where the type parameter isn't in scope.
262 let parent = if item_def_id == param_owner_def_id {
265 tcx.generics_of(item_def_id).parent
268 let result = parent.map_or(&tcx.common.empty_predicates, |parent| {
269 let icx = ItemCtxt::new(tcx, parent);
270 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
272 let mut extend = None;
274 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
275 let ast_generics = match tcx.hir().get_by_hir_id(item_hir_id) {
276 Node::TraitItem(item) => &item.generics,
278 Node::ImplItem(item) => &item.generics,
280 Node::Item(item) => {
282 ItemKind::Fn(.., ref generics, _)
283 | ItemKind::Impl(_, _, _, ref generics, ..)
284 | ItemKind::Ty(_, ref generics)
285 | ItemKind::Existential(ExistTy {
290 | ItemKind::Enum(_, ref generics)
291 | ItemKind::Struct(_, ref generics)
292 | ItemKind::Union(_, ref generics) => generics,
293 ItemKind::Trait(_, _, ref generics, ..) => {
294 // Implied `Self: Trait` and supertrait bounds.
295 if param_id == item_hir_id {
296 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
297 extend = Some((identity_trait_ref.to_predicate(), item.span));
305 Node::ForeignItem(item) => match item.node {
306 ForeignItemKind::Fn(_, _, ref generics) => generics,
313 let icx = ItemCtxt::new(tcx, item_def_id);
314 let mut result = (*result).clone();
315 result.predicates.extend(extend.into_iter());
317 .extend(icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty,
318 OnlySelfBounds(true)));
319 tcx.arena.alloc(result)
322 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
323 /// Finds bounds from `hir::Generics`. This requires scanning through the
324 /// AST. We do this to avoid having to convert *all* the bounds, which
325 /// would create artificial cycles. Instead we can only convert the
326 /// bounds for a type parameter `X` if `X::Foo` is used.
327 fn type_parameter_bounds_in_generics(
329 ast_generics: &hir::Generics,
330 param_id: hir::HirId,
332 only_self_bounds: OnlySelfBounds,
333 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
334 let from_ty_params = ast_generics
337 .filter_map(|param| match param.kind {
338 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
341 .flat_map(|bounds| bounds.iter())
342 .flat_map(|b| predicates_from_bound(self, ty, b));
344 let from_where_clauses = ast_generics
348 .filter_map(|wp| match *wp {
349 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
353 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
355 } else if !only_self_bounds.0 {
356 Some(self.to_ty(&bp.bounded_ty))
360 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
362 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
364 from_ty_params.chain(from_where_clauses).collect()
368 /// Tests whether this is the AST for a reference to the type
369 /// parameter with ID `param_id`. We use this so as to avoid running
370 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
371 /// conversion of the type to avoid inducing unnecessary cycles.
372 fn is_param<'a, 'tcx>(
373 tcx: TyCtxt<'a, 'tcx, 'tcx>,
375 param_id: hir::HirId,
377 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.node {
379 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
380 def_id == tcx.hir().local_def_id_from_hir_id(param_id)
389 fn convert_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_id: hir::HirId) {
390 let it = tcx.hir().expect_item_by_hir_id(item_id);
391 debug!("convert: item {} with id {}", it.ident, it.hir_id);
392 let def_id = tcx.hir().local_def_id_from_hir_id(item_id);
394 // These don't define types.
395 hir::ItemKind::ExternCrate(_)
396 | hir::ItemKind::Use(..)
397 | hir::ItemKind::Mod(_)
398 | hir::ItemKind::GlobalAsm(_) => {}
399 hir::ItemKind::ForeignMod(ref foreign_mod) => {
400 for item in &foreign_mod.items {
401 let def_id = tcx.hir().local_def_id_from_hir_id(item.hir_id);
402 tcx.generics_of(def_id);
404 tcx.predicates_of(def_id);
405 if let hir::ForeignItemKind::Fn(..) = item.node {
410 hir::ItemKind::Enum(ref enum_definition, _) => {
411 tcx.generics_of(def_id);
413 tcx.predicates_of(def_id);
414 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
416 hir::ItemKind::Impl(..) => {
417 tcx.generics_of(def_id);
419 tcx.impl_trait_ref(def_id);
420 tcx.predicates_of(def_id);
422 hir::ItemKind::Trait(..) => {
423 tcx.generics_of(def_id);
424 tcx.trait_def(def_id);
425 tcx.at(it.span).super_predicates_of(def_id);
426 tcx.predicates_of(def_id);
428 hir::ItemKind::TraitAlias(..) => {
429 tcx.generics_of(def_id);
430 tcx.at(it.span).super_predicates_of(def_id);
431 tcx.predicates_of(def_id);
433 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
434 tcx.generics_of(def_id);
436 tcx.predicates_of(def_id);
438 for f in struct_def.fields() {
439 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
440 tcx.generics_of(def_id);
442 tcx.predicates_of(def_id);
445 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
446 convert_variant_ctor(tcx, ctor_hir_id);
450 // Desugared from `impl Trait` -> visited by the function's return type
451 hir::ItemKind::Existential(hir::ExistTy {
452 impl_trait_fn: Some(_),
456 hir::ItemKind::Existential(..)
457 | hir::ItemKind::Ty(..)
458 | hir::ItemKind::Static(..)
459 | hir::ItemKind::Const(..)
460 | hir::ItemKind::Fn(..) => {
461 tcx.generics_of(def_id);
463 tcx.predicates_of(def_id);
464 if let hir::ItemKind::Fn(..) = it.node {
471 fn convert_trait_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, trait_item_id: hir::HirId) {
472 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
473 let def_id = tcx.hir().local_def_id_from_hir_id(trait_item.hir_id);
474 tcx.generics_of(def_id);
476 match trait_item.node {
477 hir::TraitItemKind::Const(..)
478 | hir::TraitItemKind::Type(_, Some(_))
479 | hir::TraitItemKind::Method(..) => {
481 if let hir::TraitItemKind::Method(..) = trait_item.node {
486 hir::TraitItemKind::Type(_, None) => {}
489 tcx.predicates_of(def_id);
492 fn convert_impl_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, impl_item_id: hir::HirId) {
493 let def_id = tcx.hir().local_def_id_from_hir_id(impl_item_id);
494 tcx.generics_of(def_id);
496 tcx.predicates_of(def_id);
497 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).node {
502 fn convert_variant_ctor<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ctor_id: hir::HirId) {
503 let def_id = tcx.hir().local_def_id_from_hir_id(ctor_id);
504 tcx.generics_of(def_id);
506 tcx.predicates_of(def_id);
509 fn convert_enum_variant_types<'a, 'tcx>(
510 tcx: TyCtxt<'a, 'tcx, 'tcx>,
512 variants: &[hir::Variant],
514 let def = tcx.adt_def(def_id);
515 let repr_type = def.repr.discr_type();
516 let initial = repr_type.initial_discriminant(tcx);
517 let mut prev_discr = None::<Discr<'tcx>>;
519 // fill the discriminant values and field types
520 for variant in variants {
521 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
523 if let Some(ref e) = variant.node.disr_expr {
524 let expr_did = tcx.hir().local_def_id_from_hir_id(e.hir_id);
525 def.eval_explicit_discr(tcx, expr_did)
526 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
533 "enum discriminant overflowed"
536 format!("overflowed on value after {}", prev_discr.unwrap()),
538 "explicitly set `{} = {}` if that is desired outcome",
539 variant.node.ident, wrapped_discr
543 }.unwrap_or(wrapped_discr),
546 for f in variant.node.data.fields() {
547 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
548 tcx.generics_of(def_id);
550 tcx.predicates_of(def_id);
553 // Convert the ctor, if any. This also registers the variant as
555 if let Some(ctor_hir_id) = variant.node.data.ctor_hir_id() {
556 convert_variant_ctor(tcx, ctor_hir_id);
561 fn convert_variant<'a, 'tcx>(
562 tcx: TyCtxt<'a, 'tcx, 'tcx>,
563 variant_did: Option<DefId>,
564 ctor_did: Option<DefId>,
566 discr: ty::VariantDiscr,
567 def: &hir::VariantData,
568 adt_kind: ty::AdtKind,
570 ) -> ty::VariantDef {
571 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
572 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
577 let fid = tcx.hir().local_def_id_from_hir_id(f.hir_id);
578 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
579 if let Some(prev_span) = dup_span {
584 "field `{}` is already declared",
586 ).span_label(f.span, "field already declared")
587 .span_label(prev_span, format!("`{}` first declared here", f.ident))
590 seen_fields.insert(f.ident.modern(), f.span);
596 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
600 let recovered = match def {
601 hir::VariantData::Struct(_, r) => *r,
611 CtorKind::from_hir(def),
618 fn adt_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::AdtDef {
621 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
622 let item = match tcx.hir().get_by_hir_id(hir_id) {
623 Node::Item(item) => item,
627 let repr = ReprOptions::new(tcx, def_id);
628 let (kind, variants) = match item.node {
629 ItemKind::Enum(ref def, _) => {
630 let mut distance_from_explicit = 0;
631 let variants = def.variants
634 let variant_did = Some(tcx.hir().local_def_id_from_hir_id(v.node.id));
635 let ctor_did = v.node.data.ctor_hir_id()
636 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
638 let discr = if let Some(ref e) = v.node.disr_expr {
639 distance_from_explicit = 0;
640 ty::VariantDiscr::Explicit(tcx.hir().local_def_id_from_hir_id(e.hir_id))
642 ty::VariantDiscr::Relative(distance_from_explicit)
644 distance_from_explicit += 1;
646 convert_variant(tcx, variant_did, ctor_did, v.node.ident, discr,
647 &v.node.data, AdtKind::Enum, def_id)
651 (AdtKind::Enum, variants)
653 ItemKind::Struct(ref def, _) => {
654 let variant_did = None;
655 let ctor_did = def.ctor_hir_id()
656 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
658 let variants = std::iter::once(convert_variant(
659 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
660 AdtKind::Struct, def_id,
663 (AdtKind::Struct, variants)
665 ItemKind::Union(ref def, _) => {
666 let variant_did = None;
667 let ctor_did = def.ctor_hir_id()
668 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
670 let variants = std::iter::once(convert_variant(
671 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
672 AdtKind::Union, def_id,
675 (AdtKind::Union, variants)
679 tcx.alloc_adt_def(def_id, kind, variants, repr)
682 /// Ensures that the super-predicates of the trait with a `DefId`
683 /// of `trait_def_id` are converted and stored. This also ensures that
684 /// the transitive super-predicates are converted.
685 fn super_predicates_of<'a, 'tcx>(
686 tcx: TyCtxt<'a, 'tcx, 'tcx>,
688 ) -> &'tcx ty::GenericPredicates<'tcx> {
689 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
690 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
692 let item = match tcx.hir().get_by_hir_id(trait_hir_id) {
693 Node::Item(item) => item,
694 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
697 let (generics, bounds) = match item.node {
698 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
699 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
700 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
703 let icx = ItemCtxt::new(tcx, trait_def_id);
705 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
706 let self_param_ty = tcx.mk_self_type();
707 let superbounds1 = compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
709 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
711 // Convert any explicit superbounds in the where-clause,
712 // e.g., `trait Foo where Self: Bar`.
713 // In the case of trait aliases, however, we include all bounds in the where-clause,
714 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
715 // as one of its "superpredicates".
716 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
717 let superbounds2 = icx.type_parameter_bounds_in_generics(
718 generics, item.hir_id, self_param_ty, OnlySelfBounds(!is_trait_alias));
720 // Combine the two lists to form the complete set of superbounds:
721 let superbounds: Vec<_> = superbounds1.into_iter().chain(superbounds2).collect();
723 // Now require that immediate supertraits are converted,
724 // which will, in turn, reach indirect supertraits.
725 for &(pred, span) in &superbounds {
726 debug!("superbound: {:?}", pred);
727 if let ty::Predicate::Trait(bound) = pred {
728 tcx.at(span).super_predicates_of(bound.def_id());
732 tcx.arena.alloc(ty::GenericPredicates {
734 predicates: superbounds,
738 fn trait_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::TraitDef {
739 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
740 let item = tcx.hir().expect_item_by_hir_id(hir_id);
742 let (is_auto, unsafety) = match item.node {
743 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
744 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
745 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
748 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
749 if paren_sugar && !tcx.features().unboxed_closures {
750 let mut err = tcx.sess.struct_span_err(
752 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
753 which traits can use parenthetical notation",
757 "add `#![feature(unboxed_closures)]` to \
758 the crate attributes to use it"
763 let is_marker = tcx.has_attr(def_id, sym::marker);
764 let def_path_hash = tcx.def_path_hash(def_id);
765 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
769 fn has_late_bound_regions<'a, 'tcx>(
770 tcx: TyCtxt<'a, 'tcx, 'tcx>,
773 struct LateBoundRegionsDetector<'a, 'tcx: 'a> {
774 tcx: TyCtxt<'a, 'tcx, 'tcx>,
775 outer_index: ty::DebruijnIndex,
776 has_late_bound_regions: Option<Span>,
779 impl<'a, 'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'a, 'tcx> {
780 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
781 NestedVisitorMap::None
784 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
785 if self.has_late_bound_regions.is_some() {
789 hir::TyKind::BareFn(..) => {
790 self.outer_index.shift_in(1);
791 intravisit::walk_ty(self, ty);
792 self.outer_index.shift_out(1);
794 _ => intravisit::walk_ty(self, ty),
798 fn visit_poly_trait_ref(
800 tr: &'tcx hir::PolyTraitRef,
801 m: hir::TraitBoundModifier,
803 if self.has_late_bound_regions.is_some() {
806 self.outer_index.shift_in(1);
807 intravisit::walk_poly_trait_ref(self, tr, m);
808 self.outer_index.shift_out(1);
811 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
812 if self.has_late_bound_regions.is_some() {
816 match self.tcx.named_region(lt.hir_id) {
817 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
818 Some(rl::Region::LateBound(debruijn, _, _))
819 | Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
820 Some(rl::Region::LateBound(..))
821 | Some(rl::Region::LateBoundAnon(..))
822 | Some(rl::Region::Free(..))
824 self.has_late_bound_regions = Some(lt.span);
830 fn has_late_bound_regions<'a, 'tcx>(
831 tcx: TyCtxt<'a, 'tcx, 'tcx>,
832 generics: &'tcx hir::Generics,
833 decl: &'tcx hir::FnDecl,
835 let mut visitor = LateBoundRegionsDetector {
837 outer_index: ty::INNERMOST,
838 has_late_bound_regions: None,
840 for param in &generics.params {
841 if let GenericParamKind::Lifetime { .. } = param.kind {
842 if tcx.is_late_bound(param.hir_id) {
843 return Some(param.span);
847 visitor.visit_fn_decl(decl);
848 visitor.has_late_bound_regions
852 Node::TraitItem(item) => match item.node {
853 hir::TraitItemKind::Method(ref sig, _) => {
854 has_late_bound_regions(tcx, &item.generics, &sig.decl)
858 Node::ImplItem(item) => match item.node {
859 hir::ImplItemKind::Method(ref sig, _) => {
860 has_late_bound_regions(tcx, &item.generics, &sig.decl)
864 Node::ForeignItem(item) => match item.node {
865 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
866 has_late_bound_regions(tcx, generics, fn_decl)
870 Node::Item(item) => match item.node {
871 hir::ItemKind::Fn(ref fn_decl, .., ref generics, _) => {
872 has_late_bound_regions(tcx, generics, fn_decl)
880 fn generics_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::Generics {
883 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
885 let node = tcx.hir().get_by_hir_id(hir_id);
886 let parent_def_id = match node {
887 Node::ImplItem(_) | Node::TraitItem(_) | Node::Variant(_) |
888 Node::Ctor(..) | Node::Field(_) => {
889 let parent_id = tcx.hir().get_parent_item(hir_id);
890 Some(tcx.hir().local_def_id_from_hir_id(parent_id))
892 Node::Expr(&hir::Expr {
893 node: hir::ExprKind::Closure(..),
895 }) => Some(tcx.closure_base_def_id(def_id)),
896 Node::Item(item) => match item.node {
897 ItemKind::Existential(hir::ExistTy { impl_trait_fn, .. }) => impl_trait_fn,
903 let mut opt_self = None;
904 let mut allow_defaults = false;
906 let no_generics = hir::Generics::empty();
907 let ast_generics = match node {
908 Node::TraitItem(item) => &item.generics,
910 Node::ImplItem(item) => &item.generics,
912 Node::Item(item) => {
914 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
918 ItemKind::Ty(_, ref generics)
919 | ItemKind::Enum(_, ref generics)
920 | ItemKind::Struct(_, ref generics)
921 | ItemKind::Existential(hir::ExistTy { ref generics, .. })
922 | ItemKind::Union(_, ref generics) => {
923 allow_defaults = true;
927 ItemKind::Trait(_, _, ref generics, ..)
928 | ItemKind::TraitAlias(ref generics, ..) => {
929 // Add in the self type parameter.
931 // Something of a hack: use the node id for the trait, also as
932 // the node id for the Self type parameter.
933 let param_id = item.hir_id;
935 opt_self = Some(ty::GenericParamDef {
937 name: kw::SelfUpper.as_interned_str(),
938 def_id: tcx.hir().local_def_id_from_hir_id(param_id),
939 pure_wrt_drop: false,
940 kind: ty::GenericParamDefKind::Type {
942 object_lifetime_default: rl::Set1::Empty,
947 allow_defaults = true;
955 Node::ForeignItem(item) => match item.node {
956 ForeignItemKind::Static(..) => &no_generics,
957 ForeignItemKind::Fn(_, _, ref generics) => generics,
958 ForeignItemKind::Type => &no_generics,
964 let has_self = opt_self.is_some();
965 let mut parent_has_self = false;
966 let mut own_start = has_self as u32;
967 let parent_count = parent_def_id.map_or(0, |def_id| {
968 let generics = tcx.generics_of(def_id);
969 assert_eq!(has_self, false);
970 parent_has_self = generics.has_self;
971 own_start = generics.count() as u32;
972 generics.parent_count + generics.params.len()
975 let mut params: Vec<_> = opt_self.into_iter().collect();
977 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
981 .map(|(i, param)| ty::GenericParamDef {
982 name: param.name.ident().as_interned_str(),
983 index: own_start + i as u32,
984 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
985 pure_wrt_drop: param.pure_wrt_drop,
986 kind: ty::GenericParamDefKind::Lifetime,
990 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
992 // Now create the real type parameters.
993 let type_start = own_start - has_self as u32 + params.len() as u32;
999 .filter_map(|param| {
1000 let kind = match param.kind {
1001 GenericParamKind::Type {
1006 if param.name.ident().name == kw::SelfUpper {
1009 "`Self` should not be the name of a regular parameter"
1013 if !allow_defaults && default.is_some() {
1014 if !tcx.features().default_type_parameter_fallback {
1016 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1020 "defaults for type parameters are only allowed in \
1021 `struct`, `enum`, `type`, or `trait` definitions."
1027 ty::GenericParamDefKind::Type {
1028 has_default: default.is_some(),
1029 object_lifetime_default: object_lifetime_defaults
1031 .map_or(rl::Set1::Empty, |o| o[i]),
1035 GenericParamKind::Const { .. } => {
1036 if param.name.ident().name == kw::SelfUpper {
1039 "`Self` should not be the name of a regular parameter",
1043 ty::GenericParamDefKind::Const
1048 let param_def = ty::GenericParamDef {
1049 index: type_start + i as u32,
1050 name: param.name.ident().as_interned_str(),
1051 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
1052 pure_wrt_drop: param.pure_wrt_drop,
1060 // provide junk type parameter defs - the only place that
1061 // cares about anything but the length is instantiation,
1062 // and we don't do that for closures.
1063 if let Node::Expr(&hir::Expr {
1064 node: hir::ExprKind::Closure(.., gen),
1068 let dummy_args = if gen.is_some() {
1069 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1071 &["<closure_kind>", "<closure_signature>"][..]
1078 .map(|(i, &arg)| ty::GenericParamDef {
1079 index: type_start + i as u32,
1080 name: InternedString::intern(arg),
1082 pure_wrt_drop: false,
1083 kind: ty::GenericParamDefKind::Type {
1085 object_lifetime_default: rl::Set1::Empty,
1091 if let Some(upvars) = tcx.upvars(def_id) {
1092 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1093 ty::GenericParamDef {
1094 index: type_start + i,
1095 name: InternedString::intern("<upvar>"),
1097 pure_wrt_drop: false,
1098 kind: ty::GenericParamDefKind::Type {
1100 object_lifetime_default: rl::Set1::Empty,
1108 let param_def_id_to_index = params
1110 .map(|param| (param.def_id, param.index))
1113 tcx.arena.alloc(ty::Generics {
1114 parent: parent_def_id,
1117 param_def_id_to_index,
1118 has_self: has_self || parent_has_self,
1119 has_late_bound_regions: has_late_bound_regions(tcx, node),
1123 fn report_assoc_ty_on_inherent_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, span: Span) {
1128 "associated types are not yet supported in inherent impls (see #8995)"
1132 fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
1133 checked_type_of(tcx, def_id, true).unwrap()
1136 /// Same as [`type_of`] but returns [`Option`] instead of failing.
1138 /// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
1139 /// you'd better just call [`type_of`] directly.
1140 pub fn checked_type_of<'a, 'tcx>(
1141 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1144 ) -> Option<Ty<'tcx>> {
1147 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1148 Some(hir_id) => hir_id,
1153 bug!("invalid node");
1157 let icx = ItemCtxt::new(tcx, def_id);
1159 Some(match tcx.hir().get_by_hir_id(hir_id) {
1160 Node::TraitItem(item) => match item.node {
1161 TraitItemKind::Method(..) => {
1162 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1163 tcx.mk_fn_def(def_id, substs)
1165 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1166 TraitItemKind::Type(_, None) => {
1170 span_bug!(item.span, "associated type missing default");
1174 Node::ImplItem(item) => match item.node {
1175 ImplItemKind::Method(..) => {
1176 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1177 tcx.mk_fn_def(def_id, substs)
1179 ImplItemKind::Const(ref ty, _) => icx.to_ty(ty),
1180 ImplItemKind::Existential(_) => {
1182 .impl_trait_ref(tcx.hir().get_parent_did_by_hir_id(hir_id))
1185 report_assoc_ty_on_inherent_impl(tcx, item.span);
1188 find_existential_constraints(tcx, def_id)
1190 ImplItemKind::Type(ref ty) => {
1192 .impl_trait_ref(tcx.hir().get_parent_did_by_hir_id(hir_id))
1195 report_assoc_ty_on_inherent_impl(tcx, item.span);
1202 Node::Item(item) => {
1204 ItemKind::Static(ref t, ..)
1205 | ItemKind::Const(ref t, _)
1206 | ItemKind::Ty(ref t, _)
1207 | ItemKind::Impl(.., ref t, _) => icx.to_ty(t),
1208 ItemKind::Fn(..) => {
1209 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1210 tcx.mk_fn_def(def_id, substs)
1212 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1213 let def = tcx.adt_def(def_id);
1214 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1215 tcx.mk_adt(def, substs)
1217 ItemKind::Existential(hir::ExistTy {
1218 impl_trait_fn: None,
1220 }) => find_existential_constraints(tcx, def_id),
1221 // existential types desugared from impl Trait
1222 ItemKind::Existential(hir::ExistTy {
1223 impl_trait_fn: Some(owner),
1226 tcx.typeck_tables_of(owner)
1227 .concrete_existential_types
1229 .map(|opaque| opaque.concrete_type)
1230 .unwrap_or_else(|| {
1231 // This can occur if some error in the
1232 // owner fn prevented us from populating
1233 // the `concrete_existential_types` table.
1234 tcx.sess.delay_span_bug(
1237 "owner {:?} has no existential type for {:?} in its tables",
1245 | ItemKind::TraitAlias(..)
1247 | ItemKind::ForeignMod(..)
1248 | ItemKind::GlobalAsm(..)
1249 | ItemKind::ExternCrate(..)
1250 | ItemKind::Use(..) => {
1256 "compute_type_of_item: unexpected item type: {:?}",
1263 Node::ForeignItem(foreign_item) => match foreign_item.node {
1264 ForeignItemKind::Fn(..) => {
1265 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1266 tcx.mk_fn_def(def_id, substs)
1268 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1269 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1272 Node::Ctor(&ref def) | Node::Variant(&Spanned {
1273 node: hir::VariantKind { data: ref def, .. },
1276 VariantData::Unit(..) | VariantData::Struct(..) => {
1277 tcx.type_of(tcx.hir().get_parent_did_by_hir_id(hir_id))
1279 VariantData::Tuple(..) => {
1280 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1281 tcx.mk_fn_def(def_id, substs)
1285 Node::Field(field) => icx.to_ty(&field.ty),
1287 Node::Expr(&hir::Expr {
1288 node: hir::ExprKind::Closure(.., gen),
1292 return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
1295 let substs = ty::ClosureSubsts {
1296 substs: InternalSubsts::identity_for_item(tcx, def_id),
1299 tcx.mk_closure(def_id, substs)
1302 Node::AnonConst(_) => {
1303 let parent_node = tcx.hir().get_by_hir_id(tcx.hir().get_parent_node_by_hir_id(hir_id));
1306 node: hir::TyKind::Array(_, ref constant),
1309 | Node::Ty(&hir::Ty {
1310 node: hir::TyKind::Typeof(ref constant),
1313 | Node::Expr(&hir::Expr {
1314 node: ExprKind::Repeat(_, ref constant),
1316 }) if constant.hir_id == hir_id =>
1321 Node::Variant(&Spanned {
1324 disr_expr: Some(ref e),
1328 }) if e.hir_id == hir_id =>
1330 tcx.adt_def(tcx.hir().get_parent_did_by_hir_id(hir_id))
1336 Node::Ty(&hir::Ty { node: hir::TyKind::Path(_), .. }) |
1337 Node::Expr(&hir::Expr { node: ExprKind::Struct(..), .. }) |
1338 Node::Expr(&hir::Expr { node: ExprKind::Path(_), .. }) |
1339 Node::TraitRef(..) => {
1340 let path = match parent_node {
1342 node: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1345 | Node::Expr(&hir::Expr {
1346 node: ExprKind::Path(QPath::Resolved(_, ref path)),
1351 Node::Expr(&hir::Expr { node: ExprKind::Struct(ref path, ..), .. }) => {
1352 if let QPath::Resolved(_, ref path) = **path {
1358 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(path),
1362 if let Some(path) = path {
1363 let arg_index = path.segments.iter()
1364 .filter_map(|seg| seg.args.as_ref())
1365 .map(|generic_args| generic_args.args.as_ref())
1368 .filter(|arg| arg.is_const())
1370 .filter(|(_, arg)| arg.id() == hir_id)
1371 .map(|(index, _)| index)
1378 bug!("no arg matching AnonConst in path")
1382 // We've encountered an `AnonConst` in some path, so we need to
1383 // figure out which generic parameter it corresponds to and return
1384 // the relevant type.
1385 let generics = match path.res {
1386 Res::Def(DefKind::Ctor(..), def_id) => {
1387 tcx.generics_of(tcx.parent(def_id).unwrap())
1389 Res::Def(_, def_id) => tcx.generics_of(def_id),
1390 Res::Err => return Some(tcx.types.err),
1391 _ if !fail => return None,
1393 tcx.sess.delay_span_bug(
1396 "unexpected const parent path def {:?}",
1400 return Some(tcx.types.err);
1404 generics.params.iter()
1406 if let ty::GenericParamDefKind::Const = param.kind {
1413 .map(|param| tcx.type_of(param.def_id))
1414 // This is no generic parameter associated with the arg. This is
1415 // probably from an extra arg where one is not needed.
1416 .unwrap_or(tcx.types.err)
1421 tcx.sess.delay_span_bug(
1424 "unexpected const parent path {:?}",
1428 return Some(tcx.types.err);
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 ) -> &'tcx 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 let mut predicates = (*result).clone();
1862 predicates.predicates.extend(inferred_outlives.iter().map(|&p| (p, span)));
1863 result = tcx.arena.alloc(predicates);
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 ) -> &'tcx 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 let mut predicates = (*result).clone();
1893 predicates.predicates.push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span));
1894 result = tcx.arena.alloc(predicates);
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 ) -> &'tcx 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 tcx.arena.alloc(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 = tcx.arena.alloc(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 bad_item = |span| {
2411 let msg = "malformed `target_feature` attribute input";
2412 let code = "enable = \"..\"".to_owned();
2413 tcx.sess.struct_span_err(span, &msg)
2414 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2417 let rust_features = tcx.features();
2419 // Only `enable = ...` is accepted in the meta item list
2420 if !item.check_name(sym::enable) {
2421 bad_item(item.span());
2425 // Must be of the form `enable = "..."` ( a string)
2426 let value = match item.value_str() {
2427 Some(value) => value,
2429 bad_item(item.span());
2434 // We allow comma separation to enable multiple features
2435 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2436 // Only allow whitelisted features per platform
2437 let feature_gate = match whitelist.get(feature) {
2441 "the feature named `{}` is not valid for this target",
2444 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2447 format!("`{}` is not valid for this target", feature),
2449 if feature.starts_with("+") {
2450 let valid = whitelist.contains_key(&feature[1..]);
2452 err.help("consider removing the leading `+` in the feature name");
2460 // Only allow features whose feature gates have been enabled
2461 let allowed = match feature_gate.as_ref().map(|s| *s) {
2462 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2463 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2464 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2465 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2466 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2467 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2468 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2469 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2470 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2471 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2472 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2473 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2474 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2475 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2476 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2477 Some(name) => bug!("unknown target feature gate {}", name),
2480 if !allowed && id.is_local() {
2481 feature_gate::emit_feature_err(
2482 &tcx.sess.parse_sess,
2483 feature_gate.unwrap(),
2485 feature_gate::GateIssue::Language,
2486 &format!("the target feature `{}` is currently unstable", feature),
2489 Some(Symbol::intern(feature))
2494 fn linkage_by_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId, name: &str) -> Linkage {
2495 use rustc::mir::mono::Linkage::*;
2497 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2498 // applicable to variable declarations and may not really make sense for
2499 // Rust code in the first place but whitelist them anyway and trust that
2500 // the user knows what s/he's doing. Who knows, unanticipated use cases
2501 // may pop up in the future.
2503 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2504 // and don't have to be, LLVM treats them as no-ops.
2506 "appending" => Appending,
2507 "available_externally" => AvailableExternally,
2509 "extern_weak" => ExternalWeak,
2510 "external" => External,
2511 "internal" => Internal,
2512 "linkonce" => LinkOnceAny,
2513 "linkonce_odr" => LinkOnceODR,
2514 "private" => Private,
2516 "weak_odr" => WeakODR,
2518 let span = tcx.hir().span_if_local(def_id);
2519 if let Some(span) = span {
2520 tcx.sess.span_fatal(span, "invalid linkage specified")
2523 .fatal(&format!("invalid linkage specified: {}", name))
2529 fn codegen_fn_attrs<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: DefId) -> CodegenFnAttrs {
2530 let attrs = tcx.get_attrs(id);
2532 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2534 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2536 let mut inline_span = None;
2537 for attr in attrs.iter() {
2538 if attr.check_name(sym::cold) {
2539 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2540 } else if attr.check_name(sym::allocator) {
2541 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2542 } else if attr.check_name(sym::unwind) {
2543 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2544 } else if attr.check_name(sym::ffi_returns_twice) {
2545 if tcx.is_foreign_item(id) {
2546 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2548 // `#[ffi_returns_twice]` is only allowed `extern fn`s
2553 "`#[ffi_returns_twice]` may only be used on foreign functions"
2556 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2557 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2558 } else if attr.check_name(sym::naked) {
2559 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2560 } else if attr.check_name(sym::no_mangle) {
2561 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2562 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2563 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2564 } else if attr.check_name(sym::no_debug) {
2565 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2566 } else if attr.check_name(sym::used) {
2567 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2568 } else if attr.check_name(sym::thread_local) {
2569 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2570 } else if attr.check_name(sym::export_name) {
2571 if let Some(s) = attr.value_str() {
2572 if s.as_str().contains("\0") {
2573 // `#[export_name = ...]` will be converted to a null-terminated string,
2574 // so it may not contain any null characters.
2579 "`export_name` may not contain null characters"
2582 codegen_fn_attrs.export_name = Some(s);
2584 } else if attr.check_name(sym::target_feature) {
2585 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2586 let msg = "#[target_feature(..)] can only be applied to `unsafe` functions";
2587 tcx.sess.struct_span_err(attr.span, msg)
2588 .span_label(attr.span, "can only be applied to `unsafe` functions")
2589 .span_label(tcx.def_span(id), "not an `unsafe` function")
2592 from_target_feature(
2597 &mut codegen_fn_attrs.target_features,
2599 } else if attr.check_name(sym::linkage) {
2600 if let Some(val) = attr.value_str() {
2601 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2603 } else if attr.check_name(sym::link_section) {
2604 if let Some(val) = attr.value_str() {
2605 if val.as_str().bytes().any(|b| b == 0) {
2607 "illegal null byte in link_section \
2611 tcx.sess.span_err(attr.span, &msg);
2613 codegen_fn_attrs.link_section = Some(val);
2616 } else if attr.check_name(sym::link_name) {
2617 codegen_fn_attrs.link_name = attr.value_str();
2621 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2622 if attr.path != sym::inline {
2625 match attr.meta().map(|i| i.node) {
2626 Some(MetaItemKind::Word) => {
2630 Some(MetaItemKind::List(ref items)) => {
2632 inline_span = Some(attr.span);
2633 if items.len() != 1 {
2635 tcx.sess.diagnostic(),
2638 "expected one argument"
2641 } else if list_contains_name(&items[..], sym::always) {
2643 } else if list_contains_name(&items[..], sym::never) {
2647 tcx.sess.diagnostic(),
2656 Some(MetaItemKind::NameValue(_)) => ia,
2661 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2662 if attr.path != sym::optimize {
2665 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2666 match attr.meta().map(|i| i.node) {
2667 Some(MetaItemKind::Word) => {
2668 err(attr.span, "expected one argument");
2671 Some(MetaItemKind::List(ref items)) => {
2673 inline_span = Some(attr.span);
2674 if items.len() != 1 {
2675 err(attr.span, "expected one argument");
2677 } else if list_contains_name(&items[..], sym::size) {
2679 } else if list_contains_name(&items[..], sym::speed) {
2682 err(items[0].span(), "invalid argument");
2686 Some(MetaItemKind::NameValue(_)) => ia,
2691 // If a function uses #[target_feature] it can't be inlined into general
2692 // purpose functions as they wouldn't have the right target features
2693 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2695 if codegen_fn_attrs.target_features.len() > 0 {
2696 if codegen_fn_attrs.inline == InlineAttr::Always {
2697 if let Some(span) = inline_span {
2700 "cannot use #[inline(always)] with \
2707 // Weak lang items have the same semantics as "std internal" symbols in the
2708 // sense that they're preserved through all our LTO passes and only
2709 // strippable by the linker.
2711 // Additionally weak lang items have predetermined symbol names.
2712 if tcx.is_weak_lang_item(id) {
2713 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2715 if let Some(name) = weak_lang_items::link_name(&attrs) {
2716 codegen_fn_attrs.export_name = Some(name);
2717 codegen_fn_attrs.link_name = Some(name);
2720 // Internal symbols to the standard library all have no_mangle semantics in
2721 // that they have defined symbol names present in the function name. This
2722 // also applies to weak symbols where they all have known symbol names.
2723 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2724 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;