1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::{AstConv, Bounds, SizedByDefault};
18 use crate::constrained_generic_params as cgp;
19 use crate::check::intrinsic::intrisic_operation_unsafety;
21 use crate::middle::resolve_lifetime as rl;
22 use crate::middle::weak_lang_items;
23 use rustc::mir::mono::Linkage;
24 use rustc::ty::query::Providers;
25 use rustc::ty::subst::{Subst, InternalSubsts};
26 use rustc::ty::util::Discr;
27 use rustc::ty::util::IntTypeExt;
28 use rustc::ty::subst::UnpackedKind;
29 use rustc::ty::{self, AdtKind, DefIdTree, ToPolyTraitRef, Ty, TyCtxt};
30 use rustc::ty::{ReprOptions, ToPredicate};
31 use rustc::util::captures::Captures;
32 use rustc::util::nodemap::FxHashMap;
33 use rustc_target::spec::abi;
36 use syntax::ast::{Ident, MetaItemKind};
37 use syntax::attr::{InlineAttr, OptimizeAttr, list_contains_name, mark_used};
38 use syntax::source_map::Spanned;
39 use syntax::feature_gate;
40 use syntax::symbol::{InternedString, kw, Symbol, sym};
41 use syntax_pos::{Span, DUMMY_SP};
43 use rustc::hir::def::{CtorKind, Res, DefKind};
45 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
46 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
47 use rustc::hir::GenericParamKind;
48 use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
50 use errors::Applicability;
54 struct OnlySelfBounds(bool);
56 ///////////////////////////////////////////////////////////////////////////
59 fn collect_mod_item_types<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
60 tcx.hir().visit_item_likes_in_module(
62 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor()
66 pub fn provide(providers: &mut Providers<'_>) {
67 *providers = Providers {
71 predicates_defined_on,
72 explicit_predicates_of,
74 type_param_predicates,
83 collect_mod_item_types,
88 ///////////////////////////////////////////////////////////////////////////
90 /// Context specific to some particular item. This is what implements
91 /// `AstConv`. It has information about the predicates that are defined
92 /// on the trait. Unfortunately, this predicate information is
93 /// available in various different forms at various points in the
94 /// process. So we can't just store a pointer to e.g., the AST or the
95 /// parsed ty form, we have to be more flexible. To this end, the
96 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
97 /// `get_type_parameter_bounds` requests, drawing the information from
98 /// the AST (`hir::Generics`), recursively.
99 pub struct ItemCtxt<'a, 'tcx: 'a> {
100 tcx: TyCtxt<'a, 'tcx, 'tcx>,
104 ///////////////////////////////////////////////////////////////////////////
106 struct CollectItemTypesVisitor<'a, 'tcx: 'a> {
107 tcx: TyCtxt<'a, 'tcx, 'tcx>,
110 impl<'a, 'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'a, 'tcx> {
111 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
112 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
115 fn visit_item(&mut self, item: &'tcx hir::Item) {
116 convert_item(self.tcx, item.hir_id);
117 intravisit::walk_item(self, item);
120 fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
121 for param in &generics.params {
123 hir::GenericParamKind::Lifetime { .. } => {}
124 hir::GenericParamKind::Type {
127 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
128 self.tcx.type_of(def_id);
130 hir::GenericParamKind::Type { .. } => {}
131 hir::GenericParamKind::Const { .. } => {
132 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
133 self.tcx.type_of(def_id);
137 intravisit::walk_generics(self, generics);
140 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
141 if let hir::ExprKind::Closure(..) = expr.node {
142 let def_id = self.tcx.hir().local_def_id_from_hir_id(expr.hir_id);
143 self.tcx.generics_of(def_id);
144 self.tcx.type_of(def_id);
146 intravisit::walk_expr(self, expr);
149 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
150 convert_trait_item(self.tcx, trait_item.hir_id);
151 intravisit::walk_trait_item(self, trait_item);
154 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
155 convert_impl_item(self.tcx, impl_item.hir_id);
156 intravisit::walk_impl_item(self, impl_item);
160 ///////////////////////////////////////////////////////////////////////////
161 // Utility types and common code for the above passes.
163 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
164 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_def_id: DefId) -> ItemCtxt<'a, 'tcx> {
165 ItemCtxt { tcx, item_def_id }
169 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
170 pub fn to_ty(&self, ast_ty: &hir::Ty) -> Ty<'tcx> {
171 AstConv::ast_ty_to_ty(self, ast_ty)
175 impl<'a, 'tcx> AstConv<'tcx, 'tcx> for ItemCtxt<'a, 'tcx> {
176 fn tcx<'b>(&'b self) -> TyCtxt<'b, 'tcx, 'tcx> {
180 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId)
181 -> &'tcx 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, so 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 ) -> &'tcx ty::GenericPredicates<'tcx> {
249 // In the AST, bounds can derive from two places. Either
250 // written inline like `<T : Foo>` or in a where clause like
253 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
254 let param_owner = tcx.hir().ty_param_owner(param_id);
255 let param_owner_def_id = tcx.hir().local_def_id_from_hir_id(param_owner);
256 let generics = tcx.generics_of(param_owner_def_id);
257 let index = generics.param_def_id_to_index[&def_id];
258 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id).as_interned_str());
260 // Don't look for bounds where the type parameter isn't in scope.
261 let parent = if item_def_id == param_owner_def_id {
264 tcx.generics_of(item_def_id).parent
267 let result = parent.map_or(&tcx.common.empty_predicates, |parent| {
268 let icx = ItemCtxt::new(tcx, parent);
269 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
271 let mut extend = None;
273 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
274 let ast_generics = match tcx.hir().get_by_hir_id(item_hir_id) {
275 Node::TraitItem(item) => &item.generics,
277 Node::ImplItem(item) => &item.generics,
279 Node::Item(item) => {
281 ItemKind::Fn(.., ref generics, _)
282 | ItemKind::Impl(_, _, _, ref generics, ..)
283 | ItemKind::Ty(_, ref generics)
284 | ItemKind::Existential(ExistTy {
289 | ItemKind::Enum(_, ref generics)
290 | ItemKind::Struct(_, ref generics)
291 | ItemKind::Union(_, ref generics) => generics,
292 ItemKind::Trait(_, _, ref generics, ..) => {
293 // Implied `Self: Trait` and supertrait bounds.
294 if param_id == item_hir_id {
295 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
296 extend = Some((identity_trait_ref.to_predicate(), item.span));
304 Node::ForeignItem(item) => match item.node {
305 ForeignItemKind::Fn(_, _, ref generics) => generics,
312 let icx = ItemCtxt::new(tcx, item_def_id);
313 let mut result = (*result).clone();
314 result.predicates.extend(extend.into_iter());
316 .extend(icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty,
317 OnlySelfBounds(true)));
318 tcx.arena.alloc(result)
321 impl<'a, 'tcx> ItemCtxt<'a, 'tcx> {
322 /// Finds bounds from `hir::Generics`. This requires scanning through the
323 /// AST. We do this to avoid having to convert *all* the bounds, which
324 /// would create artificial cycles. Instead we can only convert the
325 /// bounds for a type parameter `X` if `X::Foo` is used.
326 fn type_parameter_bounds_in_generics(
328 ast_generics: &hir::Generics,
329 param_id: hir::HirId,
331 only_self_bounds: OnlySelfBounds,
332 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
333 let from_ty_params = ast_generics
336 .filter_map(|param| match param.kind {
337 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
340 .flat_map(|bounds| bounds.iter())
341 .flat_map(|b| predicates_from_bound(self, ty, b));
343 let from_where_clauses = ast_generics
347 .filter_map(|wp| match *wp {
348 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
352 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
354 } else if !only_self_bounds.0 {
355 Some(self.to_ty(&bp.bounded_ty))
359 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
361 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
363 from_ty_params.chain(from_where_clauses).collect()
367 /// Tests whether this is the AST for a reference to the type
368 /// parameter with ID `param_id`. We use this so as to avoid running
369 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
370 /// conversion of the type to avoid inducing unnecessary cycles.
371 fn is_param<'a, 'tcx>(
372 tcx: TyCtxt<'a, 'tcx, 'tcx>,
374 param_id: hir::HirId,
376 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.node {
378 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
379 def_id == tcx.hir().local_def_id_from_hir_id(param_id)
388 fn convert_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_id: hir::HirId) {
389 let it = tcx.hir().expect_item_by_hir_id(item_id);
390 debug!("convert: item {} with id {}", it.ident, it.hir_id);
391 let def_id = tcx.hir().local_def_id_from_hir_id(item_id);
393 // These don't define types.
394 hir::ItemKind::ExternCrate(_)
395 | hir::ItemKind::Use(..)
396 | hir::ItemKind::Mod(_)
397 | hir::ItemKind::GlobalAsm(_) => {}
398 hir::ItemKind::ForeignMod(ref foreign_mod) => {
399 for item in &foreign_mod.items {
400 let def_id = tcx.hir().local_def_id_from_hir_id(item.hir_id);
401 tcx.generics_of(def_id);
403 tcx.predicates_of(def_id);
404 if let hir::ForeignItemKind::Fn(..) = item.node {
409 hir::ItemKind::Enum(ref enum_definition, _) => {
410 tcx.generics_of(def_id);
412 tcx.predicates_of(def_id);
413 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
415 hir::ItemKind::Impl(..) => {
416 tcx.generics_of(def_id);
418 tcx.impl_trait_ref(def_id);
419 tcx.predicates_of(def_id);
421 hir::ItemKind::Trait(..) => {
422 tcx.generics_of(def_id);
423 tcx.trait_def(def_id);
424 tcx.at(it.span).super_predicates_of(def_id);
425 tcx.predicates_of(def_id);
427 hir::ItemKind::TraitAlias(..) => {
428 tcx.generics_of(def_id);
429 tcx.at(it.span).super_predicates_of(def_id);
430 tcx.predicates_of(def_id);
432 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
433 tcx.generics_of(def_id);
435 tcx.predicates_of(def_id);
437 for f in struct_def.fields() {
438 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
439 tcx.generics_of(def_id);
441 tcx.predicates_of(def_id);
444 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
445 convert_variant_ctor(tcx, ctor_hir_id);
449 // Desugared from `impl Trait`, so visited by the function's return type.
450 hir::ItemKind::Existential(hir::ExistTy {
451 impl_trait_fn: Some(_),
455 hir::ItemKind::Existential(..)
456 | hir::ItemKind::Ty(..)
457 | hir::ItemKind::Static(..)
458 | hir::ItemKind::Const(..)
459 | hir::ItemKind::Fn(..) => {
460 tcx.generics_of(def_id);
462 tcx.predicates_of(def_id);
463 if let hir::ItemKind::Fn(..) = it.node {
470 fn convert_trait_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, trait_item_id: hir::HirId) {
471 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
472 let def_id = tcx.hir().local_def_id_from_hir_id(trait_item.hir_id);
473 tcx.generics_of(def_id);
475 match trait_item.node {
476 hir::TraitItemKind::Const(..)
477 | hir::TraitItemKind::Type(_, Some(_))
478 | hir::TraitItemKind::Method(..) => {
480 if let hir::TraitItemKind::Method(..) = trait_item.node {
485 hir::TraitItemKind::Type(_, None) => {}
488 tcx.predicates_of(def_id);
491 fn convert_impl_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, impl_item_id: hir::HirId) {
492 let def_id = tcx.hir().local_def_id_from_hir_id(impl_item_id);
493 tcx.generics_of(def_id);
495 tcx.predicates_of(def_id);
496 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).node {
501 fn convert_variant_ctor<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ctor_id: hir::HirId) {
502 let def_id = tcx.hir().local_def_id_from_hir_id(ctor_id);
503 tcx.generics_of(def_id);
505 tcx.predicates_of(def_id);
508 fn convert_enum_variant_types<'a, 'tcx>(
509 tcx: TyCtxt<'a, 'tcx, 'tcx>,
511 variants: &[hir::Variant],
513 let def = tcx.adt_def(def_id);
514 let repr_type = def.repr.discr_type();
515 let initial = repr_type.initial_discriminant(tcx);
516 let mut prev_discr = None::<Discr<'tcx>>;
518 // fill the discriminant values and field types
519 for variant in variants {
520 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
522 if let Some(ref e) = variant.node.disr_expr {
523 let expr_did = tcx.hir().local_def_id_from_hir_id(e.hir_id);
524 def.eval_explicit_discr(tcx, expr_did)
525 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
532 "enum discriminant overflowed"
535 format!("overflowed on value after {}", prev_discr.unwrap()),
537 "explicitly set `{} = {}` if that is desired outcome",
538 variant.node.ident, wrapped_discr
542 }.unwrap_or(wrapped_discr),
545 for f in variant.node.data.fields() {
546 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
547 tcx.generics_of(def_id);
549 tcx.predicates_of(def_id);
552 // Convert the ctor, if any. This also registers the variant as
554 if let Some(ctor_hir_id) = variant.node.data.ctor_hir_id() {
555 convert_variant_ctor(tcx, ctor_hir_id);
560 fn convert_variant<'a, 'tcx>(
561 tcx: TyCtxt<'a, 'tcx, 'tcx>,
562 variant_did: Option<DefId>,
563 ctor_did: Option<DefId>,
565 discr: ty::VariantDiscr,
566 def: &hir::VariantData,
567 adt_kind: ty::AdtKind,
569 ) -> ty::VariantDef {
570 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
571 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
576 let fid = tcx.hir().local_def_id_from_hir_id(f.hir_id);
577 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
578 if let Some(prev_span) = dup_span {
583 "field `{}` is already declared",
585 ).span_label(f.span, "field already declared")
586 .span_label(prev_span, format!("`{}` first declared here", f.ident))
589 seen_fields.insert(f.ident.modern(), f.span);
595 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
599 let recovered = match def {
600 hir::VariantData::Struct(_, r) => *r,
610 CtorKind::from_hir(def),
617 fn adt_def<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx ty::AdtDef {
620 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
621 let item = match tcx.hir().get_by_hir_id(hir_id) {
622 Node::Item(item) => item,
626 let repr = ReprOptions::new(tcx, def_id);
627 let (kind, variants) = match item.node {
628 ItemKind::Enum(ref def, _) => {
629 let mut distance_from_explicit = 0;
630 let variants = def.variants
633 let variant_did = Some(tcx.hir().local_def_id_from_hir_id(v.node.id));
634 let ctor_did = v.node.data.ctor_hir_id()
635 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
637 let discr = if let Some(ref e) = v.node.disr_expr {
638 distance_from_explicit = 0;
639 ty::VariantDiscr::Explicit(tcx.hir().local_def_id_from_hir_id(e.hir_id))
641 ty::VariantDiscr::Relative(distance_from_explicit)
643 distance_from_explicit += 1;
645 convert_variant(tcx, variant_did, ctor_did, v.node.ident, discr,
646 &v.node.data, AdtKind::Enum, def_id)
650 (AdtKind::Enum, variants)
652 ItemKind::Struct(ref def, _) => {
653 let variant_did = None;
654 let ctor_did = def.ctor_hir_id()
655 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
657 let variants = std::iter::once(convert_variant(
658 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
659 AdtKind::Struct, def_id,
662 (AdtKind::Struct, variants)
664 ItemKind::Union(ref def, _) => {
665 let variant_did = None;
666 let ctor_did = def.ctor_hir_id()
667 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
669 let variants = std::iter::once(convert_variant(
670 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
671 AdtKind::Union, def_id,
674 (AdtKind::Union, variants)
678 tcx.alloc_adt_def(def_id, kind, variants, repr)
681 /// Ensures that the super-predicates of the trait with a `DefId`
682 /// of `trait_def_id` are converted and stored. This also ensures that
683 /// the transitive super-predicates are converted.
684 fn super_predicates_of<'a, 'tcx>(
685 tcx: TyCtxt<'a, 'tcx, 'tcx>,
687 ) -> &'tcx ty::GenericPredicates<'tcx> {
688 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
689 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
691 let item = match tcx.hir().get_by_hir_id(trait_hir_id) {
692 Node::Item(item) => item,
693 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
696 let (generics, bounds) = match item.node {
697 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
698 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
699 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
702 let icx = ItemCtxt::new(tcx, trait_def_id);
704 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
705 let self_param_ty = tcx.mk_self_type();
706 let superbounds1 = AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No,
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 debug!("find_existential_constraints({:?})", def_id);
1477 struct ConstraintLocator<'a, 'tcx: 'a> {
1478 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1480 // (first found type span, actual type, mapping from the existential type's generic
1481 // parameters to the concrete type's generic parameters)
1483 // The mapping is an index for each use site of a generic parameter in the concrete type
1485 // The indices index into the generic parameters on the existential type.
1486 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1489 impl<'a, 'tcx> ConstraintLocator<'a, 'tcx> {
1490 fn check(&mut self, def_id: DefId) {
1491 // Don't try to check items that cannot possibly constrain the type.
1492 if !self.tcx.has_typeck_tables(def_id) {
1494 "find_existential_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1502 .typeck_tables_of(def_id)
1503 .concrete_existential_types
1505 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1507 "find_existential_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1513 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1514 let span = self.tcx.def_span(def_id);
1515 // used to quickly look up the position of a generic parameter
1516 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1517 // Skipping binder is ok, since we only use this to find generic parameters and
1519 for (idx, subst) in substs.iter().enumerate() {
1520 if let UnpackedKind::Type(ty) = subst.unpack() {
1521 if let ty::Param(p) = ty.sty {
1522 if index_map.insert(p, idx).is_some() {
1523 // There was already an entry for `p`, meaning a generic parameter
1525 self.tcx.sess.span_err(
1528 "defining existential type use restricts existential \
1529 type by using the generic parameter `{}` twice",
1536 self.tcx.sess.delay_span_bug(
1539 "non-defining exist ty use in defining scope: {:?}, {:?}",
1540 concrete_type, substs,
1546 // Compute the index within the existential type for each generic parameter used in
1547 // the concrete type.
1548 let indices = concrete_type
1549 .subst(self.tcx, substs)
1551 .filter_map(|t| match &t.sty {
1552 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1555 let is_param = |ty: Ty<'_>| match ty.sty {
1556 ty::Param(_) => true,
1559 if !substs.types().all(is_param) {
1560 self.tcx.sess.span_err(
1562 "defining existential type use does not fully define existential type",
1564 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1565 let mut ty = concrete_type.walk().fuse();
1566 let mut p_ty = prev_ty.walk().fuse();
1567 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.sty, &p.sty) {
1568 // Type parameters are equal to any other type parameter for the purpose of
1569 // concrete type equality, as it is possible to obtain the same type just
1570 // by passing matching parameters to a function.
1571 (ty::Param(_), ty::Param(_)) => true,
1574 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1575 debug!("find_existential_constraints: span={:?}", span);
1576 // Found different concrete types for the existential type.
1577 let mut err = self.tcx.sess.struct_span_err(
1579 "concrete type differs from previous defining existential type use",
1583 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1585 err.span_note(prev_span, "previous use here");
1587 } else if indices != *prev_indices {
1588 // Found "same" concrete types, but the generic parameter order differs.
1589 let mut err = self.tcx.sess.struct_span_err(
1591 "concrete type's generic parameters differ from previous defining use",
1593 use std::fmt::Write;
1594 let mut s = String::new();
1595 write!(s, "expected [").unwrap();
1596 let list = |s: &mut String, indices: &Vec<usize>| {
1597 let mut indices = indices.iter().cloned();
1598 if let Some(first) = indices.next() {
1599 write!(s, "`{}`", substs[first]).unwrap();
1601 write!(s, ", `{}`", substs[i]).unwrap();
1605 list(&mut s, prev_indices);
1606 write!(s, "], got [").unwrap();
1607 list(&mut s, &indices);
1608 write!(s, "]").unwrap();
1609 err.span_label(span, s);
1610 err.span_note(prev_span, "previous use here");
1614 self.found = Some((span, concrete_type, indices));
1618 "find_existential_constraints: no constraint for `{:?}` at `{:?}`",
1626 impl<'a, 'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'a, 'tcx> {
1627 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1628 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1630 fn visit_item(&mut self, it: &'tcx Item) {
1631 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1632 // The existential type itself or its children are not within its reveal scope.
1633 if def_id != self.def_id {
1635 intravisit::walk_item(self, it);
1638 fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
1639 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1640 // The existential type itself or its children are not within its reveal scope.
1641 if def_id != self.def_id {
1643 intravisit::walk_impl_item(self, it);
1646 fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
1647 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1649 intravisit::walk_trait_item(self, it);
1653 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1654 let scope = tcx.hir()
1655 .get_defining_scope(hir_id)
1656 .expect("could not get defining scope");
1657 let mut locator = ConstraintLocator {
1663 debug!("find_existential_constraints: scope={:?}", scope);
1665 if scope == hir::CRATE_HIR_ID {
1666 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1668 debug!("find_existential_constraints: scope={:?}", tcx.hir().get_by_hir_id(scope));
1669 match tcx.hir().get_by_hir_id(scope) {
1670 Node::Item(ref it) => intravisit::walk_item(&mut locator, it),
1671 Node::ImplItem(ref it) => intravisit::walk_impl_item(&mut locator, it),
1672 Node::TraitItem(ref it) => intravisit::walk_trait_item(&mut locator, it),
1674 "{:?} is not a valid scope for an existential type item",
1680 match locator.found {
1681 Some((_, ty, _)) => ty,
1683 let span = tcx.def_span(def_id);
1684 tcx.sess.span_err(span, "could not find defining uses");
1690 fn fn_sig<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ty::PolyFnSig<'tcx> {
1692 use rustc::hir::Node::*;
1694 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1696 let icx = ItemCtxt::new(tcx, def_id);
1698 match tcx.hir().get_by_hir_id(hir_id) {
1699 TraitItem(hir::TraitItem {
1700 node: TraitItemKind::Method(sig, _),
1703 | ImplItem(hir::ImplItem {
1704 node: ImplItemKind::Method(sig, _),
1706 }) => AstConv::ty_of_fn(&icx, sig.header.unsafety, sig.header.abi, &sig.decl),
1709 node: ItemKind::Fn(decl, header, _, _),
1711 }) => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl),
1713 ForeignItem(&hir::ForeignItem {
1714 node: ForeignItemKind::Fn(ref fn_decl, _, _),
1717 let abi = tcx.hir().get_foreign_abi_by_hir_id(hir_id);
1718 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1721 Ctor(data) | Variant(Spanned {
1722 node: hir::VariantKind { data, .. },
1724 }) if data.ctor_hir_id().is_some() => {
1725 let ty = tcx.type_of(tcx.hir().get_parent_did_by_hir_id(hir_id));
1726 let inputs = data.fields()
1728 .map(|f| tcx.type_of(tcx.hir().local_def_id_from_hir_id(f.hir_id)));
1729 ty::Binder::bind(tcx.mk_fn_sig(
1733 hir::Unsafety::Normal,
1739 node: hir::ExprKind::Closure(..),
1742 // Closure signatures are not like other function
1743 // signatures and cannot be accessed through `fn_sig`. For
1744 // example, a closure signature excludes the `self`
1745 // argument. In any case they are embedded within the
1746 // closure type as part of the `ClosureSubsts`.
1749 // the signature of a closure, you should use the
1750 // `closure_sig` method on the `ClosureSubsts`:
1752 // closure_substs.closure_sig(def_id, tcx)
1754 // or, inside of an inference context, you can use
1756 // infcx.closure_sig(def_id, closure_substs)
1757 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1761 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1766 fn impl_trait_ref<'a, 'tcx>(
1767 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1769 ) -> Option<ty::TraitRef<'tcx>> {
1770 let icx = ItemCtxt::new(tcx, def_id);
1772 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1773 match tcx.hir().expect_item_by_hir_id(hir_id).node {
1774 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1775 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1776 let selfty = tcx.type_of(def_id);
1777 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1784 fn impl_polarity<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> hir::ImplPolarity {
1785 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1786 match tcx.hir().expect_item_by_hir_id(hir_id).node {
1787 hir::ItemKind::Impl(_, polarity, ..) => polarity,
1788 ref item => bug!("impl_polarity: {:?} not an impl", item),
1792 /// Returns the early-bound lifetimes declared in this generics
1793 /// listing. For anything other than fns/methods, this is just all
1794 /// the lifetimes that are declared. For fns or methods, we have to
1795 /// screen out those that do not appear in any where-clauses etc using
1796 /// `resolve_lifetime::early_bound_lifetimes`.
1797 fn early_bound_lifetimes_from_generics<'a, 'tcx>(
1798 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1799 generics: &'a hir::Generics,
1800 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {
1804 .filter(move |param| match param.kind {
1805 GenericParamKind::Lifetime { .. } => {
1806 !tcx.is_late_bound(param.hir_id)
1812 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1813 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1814 /// inferred constraints concerning which regions outlive other regions.
1815 fn predicates_defined_on<'a, 'tcx>(
1816 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1818 ) -> &'tcx ty::GenericPredicates<'tcx> {
1819 debug!("predicates_defined_on({:?})", def_id);
1820 let mut result = tcx.explicit_predicates_of(def_id);
1822 "predicates_defined_on: explicit_predicates_of({:?}) = {:?}",
1826 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1827 if !inferred_outlives.is_empty() {
1828 let span = tcx.def_span(def_id);
1830 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1834 let mut predicates = (*result).clone();
1835 predicates.predicates.extend(inferred_outlives.iter().map(|&p| (p, span)));
1836 result = tcx.arena.alloc(predicates);
1838 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1842 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1843 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1844 /// `Self: Trait` predicates for traits.
1845 fn predicates_of<'a, 'tcx>(
1846 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1848 ) -> &'tcx ty::GenericPredicates<'tcx> {
1849 let mut result = tcx.predicates_defined_on(def_id);
1851 if tcx.is_trait(def_id) {
1852 // For traits, add `Self: Trait` predicate. This is
1853 // not part of the predicates that a user writes, but it
1854 // is something that one must prove in order to invoke a
1855 // method or project an associated type.
1857 // In the chalk setup, this predicate is not part of the
1858 // "predicates" for a trait item. But it is useful in
1859 // rustc because if you directly (e.g.) invoke a trait
1860 // method like `Trait::method(...)`, you must naturally
1861 // prove that the trait applies to the types that were
1862 // used, and adding the predicate into this list ensures
1863 // that this is done.
1864 let span = tcx.def_span(def_id);
1865 let mut predicates = (*result).clone();
1866 predicates.predicates.push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span));
1867 result = tcx.arena.alloc(predicates);
1869 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1873 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1874 /// N.B., this does not include any implied/inferred constraints.
1875 fn explicit_predicates_of<'a, 'tcx>(
1876 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1878 ) -> &'tcx ty::GenericPredicates<'tcx> {
1880 use rustc_data_structures::fx::FxHashSet;
1882 debug!("explicit_predicates_of(def_id={:?})", def_id);
1884 /// A data structure with unique elements, which preserves order of insertion.
1885 /// Preserving the order of insertion is important here so as not to break
1886 /// compile-fail UI tests.
1887 struct UniquePredicates<'tcx> {
1888 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1889 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1892 impl<'tcx> UniquePredicates<'tcx> {
1896 uniques: FxHashSet::default(),
1900 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
1901 if self.uniques.insert(value) {
1902 self.predicates.push(value);
1906 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
1913 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1914 Some(hir_id) => hir_id,
1915 None => return tcx.predicates_of(def_id),
1917 let node = tcx.hir().get_by_hir_id(hir_id);
1919 let mut is_trait = None;
1920 let mut is_default_impl_trait = None;
1922 let icx = ItemCtxt::new(tcx, def_id);
1923 let no_generics = hir::Generics::empty();
1924 let empty_trait_items = HirVec::new();
1926 let mut predicates = UniquePredicates::new();
1928 let ast_generics = match node {
1929 Node::TraitItem(item) => &item.generics,
1931 Node::ImplItem(item) => match item.node {
1932 ImplItemKind::Existential(ref bounds) => {
1933 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1934 let opaque_ty = tcx.mk_opaque(def_id, substs);
1936 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
1937 let bounds = AstConv::compute_bounds(
1941 SizedByDefault::Yes,
1942 tcx.def_span(def_id),
1945 predicates.extend(bounds.predicates(tcx, opaque_ty));
1948 _ => &item.generics,
1951 Node::Item(item) => {
1953 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
1954 if defaultness.is_default() {
1955 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1959 ItemKind::Fn(.., ref generics, _)
1960 | ItemKind::Ty(_, ref generics)
1961 | ItemKind::Enum(_, ref generics)
1962 | ItemKind::Struct(_, ref generics)
1963 | ItemKind::Union(_, ref generics) => generics,
1965 ItemKind::Trait(_, _, ref generics, .., ref items) => {
1966 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
1969 ItemKind::TraitAlias(ref generics, _) => {
1970 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &empty_trait_items));
1973 ItemKind::Existential(ExistTy {
1979 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1980 let opaque_ty = tcx.mk_opaque(def_id, substs);
1982 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
1983 let bounds = AstConv::compute_bounds(
1987 SizedByDefault::Yes,
1988 tcx.def_span(def_id),
1991 let bounds_predicates = bounds.predicates(tcx, opaque_ty);
1992 if impl_trait_fn.is_some() {
1994 return tcx.arena.alloc(ty::GenericPredicates {
1996 predicates: bounds_predicates,
1999 // named existential types
2000 predicates.extend(bounds_predicates);
2009 Node::ForeignItem(item) => match item.node {
2010 ForeignItemKind::Static(..) => &no_generics,
2011 ForeignItemKind::Fn(_, _, ref generics) => generics,
2012 ForeignItemKind::Type => &no_generics,
2018 let generics = tcx.generics_of(def_id);
2019 let parent_count = generics.parent_count as u32;
2020 let has_own_self = generics.has_self && parent_count == 0;
2022 // Below we'll consider the bounds on the type parameters (including `Self`)
2023 // and the explicit where-clauses, but to get the full set of predicates
2024 // on a trait we need to add in the supertrait bounds and bounds found on
2025 // associated types.
2026 if let Some((_trait_ref, _)) = is_trait {
2027 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2030 // In default impls, we can assume that the self type implements
2031 // the trait. So in:
2033 // default impl Foo for Bar { .. }
2035 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2036 // (see below). Recall that a default impl is not itself an impl, but rather a
2037 // set of defaults that can be incorporated into another impl.
2038 if let Some(trait_ref) = is_default_impl_trait {
2039 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2042 // Collect the region predicates that were declared inline as
2043 // well. In the case of parameters declared on a fn or method, we
2044 // have to be careful to only iterate over early-bound regions.
2045 let mut index = parent_count + has_own_self as u32;
2046 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2047 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2048 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
2050 name: param.name.ident().as_interned_str(),
2055 GenericParamKind::Lifetime { .. } => {
2056 param.bounds.iter().for_each(|bound| match bound {
2057 hir::GenericBound::Outlives(lt) => {
2058 let bound = AstConv::ast_region_to_region(&icx, <, None);
2059 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2060 predicates.push((outlives.to_predicate(), lt.span));
2069 // Collect the predicates that were written inline by the user on each
2070 // type parameter (e.g., `<T: Foo>`).
2071 for param in &ast_generics.params {
2072 if let GenericParamKind::Type { .. } = param.kind {
2073 let name = param.name.ident().as_interned_str();
2074 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2077 let sized = SizedByDefault::Yes;
2078 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2079 predicates.extend(bounds.predicates(tcx, param_ty));
2083 // Add in the bounds that appear in the where-clause.
2084 let where_clause = &ast_generics.where_clause;
2085 for predicate in &where_clause.predicates {
2087 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2088 let ty = icx.to_ty(&bound_pred.bounded_ty);
2090 // Keep the type around in a dummy predicate, in case of no bounds.
2091 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2092 // is still checked for WF.
2093 if bound_pred.bounds.is_empty() {
2094 if let ty::Param(_) = ty.sty {
2095 // This is a `where T:`, which can be in the HIR from the
2096 // transformation that moves `?Sized` to `T`'s declaration.
2097 // We can skip the predicate because type parameters are
2098 // trivially WF, but also we *should*, to avoid exposing
2099 // users who never wrote `where Type:,` themselves, to
2100 // compiler/tooling bugs from not handling WF predicates.
2102 let span = bound_pred.bounded_ty.span;
2103 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2105 (ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
2110 for bound in bound_pred.bounds.iter() {
2112 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2113 let mut bounds = Bounds::default();
2115 let (trait_ref, _) = AstConv::instantiate_poly_trait_ref(
2122 predicates.push((trait_ref.to_predicate(), poly_trait_ref.span));
2123 predicates.extend(bounds.predicates(tcx, ty));
2126 &hir::GenericBound::Outlives(ref lifetime) => {
2127 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2128 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2129 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2135 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2136 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2137 predicates.extend(region_pred.bounds.iter().map(|bound| {
2138 let (r2, span) = match bound {
2139 hir::GenericBound::Outlives(lt) => {
2140 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2144 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2146 (ty::Predicate::RegionOutlives(pred), span)
2150 &hir::WherePredicate::EqPredicate(..) => {
2156 // Add predicates from associated type bounds.
2157 if let Some((self_trait_ref, trait_items)) = is_trait {
2158 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2159 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2160 let bounds = match trait_item.node {
2161 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2162 _ => return Vec::new().into_iter()
2166 tcx.mk_projection(tcx.hir().local_def_id_from_hir_id(trait_item.hir_id),
2167 self_trait_ref.substs);
2169 let bounds = AstConv::compute_bounds(
2170 &ItemCtxt::new(tcx, def_id),
2173 SizedByDefault::Yes,
2177 bounds.predicates(tcx, assoc_ty).into_iter()
2181 let mut predicates = predicates.predicates;
2183 // Subtle: before we store the predicates into the tcx, we
2184 // sort them so that predicates like `T: Foo<Item=U>` come
2185 // before uses of `U`. This avoids false ambiguity errors
2186 // in trait checking. See `setup_constraining_predicates`
2188 if let Node::Item(&Item {
2189 node: ItemKind::Impl(..),
2193 let self_ty = tcx.type_of(def_id);
2194 let trait_ref = tcx.impl_trait_ref(def_id);
2195 cgp::setup_constraining_predicates(
2199 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2203 let result = tcx.arena.alloc(ty::GenericPredicates {
2204 parent: generics.parent,
2207 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2211 /// Converts a specific `GenericBound` from the AST into a set of
2212 /// predicates that apply to the self type. A vector is returned
2213 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2214 /// predicates) to one (`T: Foo`) to many (`T: Bar<X=i32>` adds `T: Bar`
2215 /// and `<T as Bar>::X == i32`).
2216 fn predicates_from_bound<'tcx>(
2217 astconv: &dyn AstConv<'tcx, 'tcx>,
2219 bound: &hir::GenericBound,
2220 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2222 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2223 let mut bounds = Bounds::default();
2224 let (pred, _) = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut bounds);
2225 iter::once((pred.to_predicate(), tr.span))
2226 .chain(bounds.predicates(astconv.tcx(), param_ty))
2229 hir::GenericBound::Outlives(ref lifetime) => {
2230 let region = astconv.ast_region_to_region(lifetime, None);
2231 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2232 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2234 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2238 fn compute_sig_of_foreign_fn_decl<'a, 'tcx>(
2239 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2243 ) -> ty::PolyFnSig<'tcx> {
2244 let unsafety = if abi == abi::Abi::RustIntrinsic {
2245 intrisic_operation_unsafety(&*tcx.item_name(def_id).as_str())
2247 hir::Unsafety::Unsafe
2249 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2251 // Feature gate SIMD types in FFI, since I am not sure that the
2252 // ABIs are handled at all correctly. -huonw
2253 if abi != abi::Abi::RustIntrinsic
2254 && abi != abi::Abi::PlatformIntrinsic
2255 && !tcx.features().simd_ffi
2257 let check = |ast_ty: &hir::Ty, ty: Ty<'_>| {
2263 "use of SIMD type `{}` in FFI is highly experimental and \
2264 may result in invalid code",
2265 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2268 .help("add #![feature(simd_ffi)] to the crate attributes to enable")
2272 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2275 if let hir::Return(ref ty) = decl.output {
2276 check(&ty, *fty.output().skip_binder())
2283 fn is_foreign_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
2284 match tcx.hir().get_if_local(def_id) {
2285 Some(Node::ForeignItem(..)) => true,
2287 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2291 fn static_mutability<'a, 'tcx>(
2292 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2294 ) -> Option<hir::Mutability> {
2295 match tcx.hir().get_if_local(def_id) {
2296 Some(Node::Item(&hir::Item {
2297 node: hir::ItemKind::Static(_, mutbl, _), ..
2299 Some(Node::ForeignItem( &hir::ForeignItem {
2300 node: hir::ForeignItemKind::Static(_, mutbl), ..
2303 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2307 fn from_target_feature(
2308 tcx: TyCtxt<'_, '_, '_>,
2310 attr: &ast::Attribute,
2311 whitelist: &FxHashMap<String, Option<Symbol>>,
2312 target_features: &mut Vec<Symbol>,
2314 let list = match attr.meta_item_list() {
2318 let bad_item = |span| {
2319 let msg = "malformed `target_feature` attribute input";
2320 let code = "enable = \"..\"".to_owned();
2321 tcx.sess.struct_span_err(span, &msg)
2322 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2325 let rust_features = tcx.features();
2327 // Only `enable = ...` is accepted in the meta-item list.
2328 if !item.check_name(sym::enable) {
2329 bad_item(item.span());
2333 // Must be of the form `enable = "..."` (a string).
2334 let value = match item.value_str() {
2335 Some(value) => value,
2337 bad_item(item.span());
2342 // We allow comma separation to enable multiple features.
2343 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2344 // Only allow whitelisted features per platform.
2345 let feature_gate = match whitelist.get(feature) {
2349 "the feature named `{}` is not valid for this target",
2352 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2355 format!("`{}` is not valid for this target", feature),
2357 if feature.starts_with("+") {
2358 let valid = whitelist.contains_key(&feature[1..]);
2360 err.help("consider removing the leading `+` in the feature name");
2368 // Only allow features whose feature gates have been enabled.
2369 let allowed = match feature_gate.as_ref().map(|s| *s) {
2370 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2371 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2372 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2373 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2374 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2375 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2376 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2377 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2378 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2379 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2380 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2381 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2382 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2383 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2384 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2385 Some(name) => bug!("unknown target feature gate {}", name),
2388 if !allowed && id.is_local() {
2389 feature_gate::emit_feature_err(
2390 &tcx.sess.parse_sess,
2391 feature_gate.unwrap(),
2393 feature_gate::GateIssue::Language,
2394 &format!("the target feature `{}` is currently unstable", feature),
2397 Some(Symbol::intern(feature))
2402 fn linkage_by_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId, name: &str) -> Linkage {
2403 use rustc::mir::mono::Linkage::*;
2405 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2406 // applicable to variable declarations and may not really make sense for
2407 // Rust code in the first place but whitelist them anyway and trust that
2408 // the user knows what s/he's doing. Who knows, unanticipated use cases
2409 // may pop up in the future.
2411 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2412 // and don't have to be, LLVM treats them as no-ops.
2414 "appending" => Appending,
2415 "available_externally" => AvailableExternally,
2417 "extern_weak" => ExternalWeak,
2418 "external" => External,
2419 "internal" => Internal,
2420 "linkonce" => LinkOnceAny,
2421 "linkonce_odr" => LinkOnceODR,
2422 "private" => Private,
2424 "weak_odr" => WeakODR,
2426 let span = tcx.hir().span_if_local(def_id);
2427 if let Some(span) = span {
2428 tcx.sess.span_fatal(span, "invalid linkage specified")
2431 .fatal(&format!("invalid linkage specified: {}", name))
2437 fn codegen_fn_attrs<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: DefId) -> CodegenFnAttrs {
2438 let attrs = tcx.get_attrs(id);
2440 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2442 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2444 let mut inline_span = None;
2445 for attr in attrs.iter() {
2446 if attr.check_name(sym::cold) {
2447 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2448 } else if attr.check_name(sym::rustc_allocator) {
2449 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2450 } else if attr.check_name(sym::unwind) {
2451 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2452 } else if attr.check_name(sym::ffi_returns_twice) {
2453 if tcx.is_foreign_item(id) {
2454 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2456 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2461 "`#[ffi_returns_twice]` may only be used on foreign functions"
2464 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2465 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2466 } else if attr.check_name(sym::naked) {
2467 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2468 } else if attr.check_name(sym::no_mangle) {
2469 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2470 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2471 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2472 } else if attr.check_name(sym::no_debug) {
2473 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2474 } else if attr.check_name(sym::used) {
2475 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2476 } else if attr.check_name(sym::thread_local) {
2477 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2478 } else if attr.check_name(sym::export_name) {
2479 if let Some(s) = attr.value_str() {
2480 if s.as_str().contains("\0") {
2481 // `#[export_name = ...]` will be converted to a null-terminated string,
2482 // so it may not contain any null characters.
2487 "`export_name` may not contain null characters"
2490 codegen_fn_attrs.export_name = Some(s);
2492 } else if attr.check_name(sym::target_feature) {
2493 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2494 let msg = "#[target_feature(..)] can only be applied to `unsafe` functions";
2495 tcx.sess.struct_span_err(attr.span, msg)
2496 .span_label(attr.span, "can only be applied to `unsafe` functions")
2497 .span_label(tcx.def_span(id), "not an `unsafe` function")
2500 from_target_feature(
2505 &mut codegen_fn_attrs.target_features,
2507 } else if attr.check_name(sym::linkage) {
2508 if let Some(val) = attr.value_str() {
2509 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2511 } else if attr.check_name(sym::link_section) {
2512 if let Some(val) = attr.value_str() {
2513 if val.as_str().bytes().any(|b| b == 0) {
2515 "illegal null byte in link_section \
2519 tcx.sess.span_err(attr.span, &msg);
2521 codegen_fn_attrs.link_section = Some(val);
2524 } else if attr.check_name(sym::link_name) {
2525 codegen_fn_attrs.link_name = attr.value_str();
2529 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2530 if attr.path != sym::inline {
2533 match attr.meta().map(|i| i.node) {
2534 Some(MetaItemKind::Word) => {
2538 Some(MetaItemKind::List(ref items)) => {
2540 inline_span = Some(attr.span);
2541 if items.len() != 1 {
2543 tcx.sess.diagnostic(),
2546 "expected one argument"
2549 } else if list_contains_name(&items[..], sym::always) {
2551 } else if list_contains_name(&items[..], sym::never) {
2555 tcx.sess.diagnostic(),
2564 Some(MetaItemKind::NameValue(_)) => ia,
2569 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2570 if attr.path != sym::optimize {
2573 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2574 match attr.meta().map(|i| i.node) {
2575 Some(MetaItemKind::Word) => {
2576 err(attr.span, "expected one argument");
2579 Some(MetaItemKind::List(ref items)) => {
2581 inline_span = Some(attr.span);
2582 if items.len() != 1 {
2583 err(attr.span, "expected one argument");
2585 } else if list_contains_name(&items[..], sym::size) {
2587 } else if list_contains_name(&items[..], sym::speed) {
2590 err(items[0].span(), "invalid argument");
2594 Some(MetaItemKind::NameValue(_)) => ia,
2599 // If a function uses #[target_feature] it can't be inlined into general
2600 // purpose functions as they wouldn't have the right target features
2601 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2603 if codegen_fn_attrs.target_features.len() > 0 {
2604 if codegen_fn_attrs.inline == InlineAttr::Always {
2605 if let Some(span) = inline_span {
2608 "cannot use #[inline(always)] with \
2615 // Weak lang items have the same semantics as "std internal" symbols in the
2616 // sense that they're preserved through all our LTO passes and only
2617 // strippable by the linker.
2619 // Additionally weak lang items have predetermined symbol names.
2620 if tcx.is_weak_lang_item(id) {
2621 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2623 if let Some(name) = weak_lang_items::link_name(&attrs) {
2624 codegen_fn_attrs.export_name = Some(name);
2625 codegen_fn_attrs.link_name = Some(name);
2628 // Internal symbols to the standard library all have no_mangle semantics in
2629 // that they have defined symbol names present in the function name. This
2630 // also applies to weak symbols where they all have known symbol names.
2631 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2632 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;