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::check::intrinsic::intrinsic_operation_unsafety;
19 use crate::constrained_generic_params as cgp;
20 use crate::middle::resolve_lifetime as rl;
22 use rustc_ast::ast::MetaItemKind;
23 use rustc_attr::{list_contains_name, mark_used, InlineAttr, OptimizeAttr};
24 use rustc_data_structures::captures::Captures;
25 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
26 use rustc_errors::{struct_span_err, Applicability};
28 use rustc_hir::def::{CtorKind, DefKind, Res};
29 use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
30 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
31 use rustc_hir::weak_lang_items;
32 use rustc_hir::{GenericParamKind, Node};
33 use rustc_middle::hir::map::blocks::FnLikeNode;
34 use rustc_middle::hir::map::Map;
35 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
36 use rustc_middle::mir::mono::Linkage;
37 use rustc_middle::ty::query::Providers;
38 use rustc_middle::ty::subst::{InternalSubsts, Subst};
39 use rustc_middle::ty::util::Discr;
40 use rustc_middle::ty::util::IntTypeExt;
41 use rustc_middle::ty::{self, AdtKind, Const, ToPolyTraitRef, Ty, TyCtxt};
42 use rustc_middle::ty::{ReprOptions, ToPredicate, WithConstness};
43 use rustc_session::lint;
44 use rustc_session::parse::feature_err;
45 use rustc_span::symbol::{kw, sym, Ident, Symbol};
46 use rustc_span::{Span, DUMMY_SP};
47 use rustc_target::spec::abi;
48 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
52 struct OnlySelfBounds(bool);
54 ///////////////////////////////////////////////////////////////////////////
57 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: DefId) {
58 tcx.hir().visit_item_likes_in_module(
60 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
64 pub fn provide(providers: &mut Providers<'_>) {
65 *providers = Providers {
66 type_of: type_of::type_of,
69 predicates_defined_on,
70 explicit_predicates_of,
72 type_param_predicates,
82 collect_mod_item_types,
87 ///////////////////////////////////////////////////////////////////////////
89 /// Context specific to some particular item. This is what implements
90 /// `AstConv`. It has information about the predicates that are defined
91 /// on the trait. Unfortunately, this predicate information is
92 /// available in various different forms at various points in the
93 /// process. So we can't just store a pointer to e.g., the AST or the
94 /// parsed ty form, we have to be more flexible. To this end, the
95 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
96 /// `get_type_parameter_bounds` requests, drawing the information from
97 /// the AST (`hir::Generics`), recursively.
98 pub struct ItemCtxt<'tcx> {
103 ///////////////////////////////////////////////////////////////////////////
106 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
108 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
109 type Map = intravisit::ErasedMap<'v>;
111 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
112 NestedVisitorMap::None
114 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
115 if let hir::TyKind::Infer = t.kind {
118 intravisit::walk_ty(self, t)
122 struct CollectItemTypesVisitor<'tcx> {
126 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
127 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
128 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
129 crate fn placeholder_type_error(
132 generics: &[hir::GenericParam<'_>],
133 placeholder_types: Vec<Span>,
136 if placeholder_types.is_empty() {
139 let type_name = generics.next_type_param_name(None);
141 let mut sugg: Vec<_> =
142 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
143 if generics.is_empty() {
144 sugg.push((span, format!("<{}>", type_name)));
145 } else if let Some(arg) = generics.iter().find(|arg| match arg.name {
146 hir::ParamName::Plain(Ident { name: kw::Underscore, .. }) => true,
149 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
150 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
151 sugg.push((arg.span, (*type_name).to_string()));
153 let last = generics.iter().last().unwrap();
155 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
156 last.bounds_span().unwrap_or(last.span).shrink_to_hi(),
157 format!(", {}", type_name),
160 let mut err = bad_placeholder_type(tcx, placeholder_types);
162 err.multipart_suggestion(
163 "use type parameters instead",
165 Applicability::HasPlaceholders,
171 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
172 let (generics, suggest) = match &item.kind {
173 hir::ItemKind::Union(_, generics)
174 | hir::ItemKind::Enum(_, generics)
175 | hir::ItemKind::TraitAlias(generics, _)
176 | hir::ItemKind::Trait(_, _, generics, ..)
177 | hir::ItemKind::Impl { generics, .. }
178 | hir::ItemKind::Struct(_, generics) => (generics, true),
179 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
180 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
181 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
185 let mut visitor = PlaceholderHirTyCollector::default();
186 visitor.visit_item(item);
188 placeholder_type_error(tcx, generics.span, &generics.params[..], visitor.0, suggest);
191 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
192 type Map = Map<'tcx>;
194 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
195 NestedVisitorMap::OnlyBodies(self.tcx.hir())
198 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
199 convert_item(self.tcx, item.hir_id);
200 reject_placeholder_type_signatures_in_item(self.tcx, item);
201 intravisit::walk_item(self, item);
204 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
205 for param in generics.params {
207 hir::GenericParamKind::Lifetime { .. } => {}
208 hir::GenericParamKind::Type { default: Some(_), .. } => {
209 let def_id = self.tcx.hir().local_def_id(param.hir_id);
210 self.tcx.ensure().type_of(def_id);
212 hir::GenericParamKind::Type { .. } => {}
213 hir::GenericParamKind::Const { .. } => {
214 let def_id = self.tcx.hir().local_def_id(param.hir_id);
215 self.tcx.ensure().type_of(def_id);
219 intravisit::walk_generics(self, generics);
222 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
223 if let hir::ExprKind::Closure(..) = expr.kind {
224 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
225 self.tcx.ensure().generics_of(def_id);
226 self.tcx.ensure().type_of(def_id);
228 intravisit::walk_expr(self, expr);
231 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
232 convert_trait_item(self.tcx, trait_item.hir_id);
233 intravisit::walk_trait_item(self, trait_item);
236 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
237 convert_impl_item(self.tcx, impl_item.hir_id);
238 intravisit::walk_impl_item(self, impl_item);
242 ///////////////////////////////////////////////////////////////////////////
243 // Utility types and common code for the above passes.
245 fn bad_placeholder_type(
247 mut spans: Vec<Span>,
248 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
250 let mut err = struct_span_err!(
254 "the type placeholder `_` is not allowed within types on item signatures",
257 err.span_label(span, "not allowed in type signatures");
262 impl ItemCtxt<'tcx> {
263 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
264 ItemCtxt { tcx, item_def_id }
267 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
268 AstConv::ast_ty_to_ty(self, ast_ty)
271 pub fn hir_id(&self) -> hir::HirId {
272 self.tcx.hir().as_local_hir_id(self.item_def_id.expect_local())
275 pub fn node(&self) -> hir::Node<'tcx> {
276 self.tcx.hir().get(self.hir_id())
280 impl AstConv<'tcx> for ItemCtxt<'tcx> {
281 fn tcx(&self) -> TyCtxt<'tcx> {
285 fn item_def_id(&self) -> Option<DefId> {
286 Some(self.item_def_id)
289 fn default_constness_for_trait_bounds(&self) -> hir::Constness {
290 if let Some(fn_like) = FnLikeNode::from_node(self.node()) {
293 hir::Constness::NotConst
297 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
298 self.tcx.at(span).type_param_predicates((self.item_def_id, def_id.expect_local()))
301 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
305 fn allow_ty_infer(&self) -> bool {
309 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
310 self.tcx().sess.delay_span_bug(span, "bad placeholder type");
317 _: Option<&ty::GenericParamDef>,
319 ) -> &'tcx Const<'tcx> {
320 bad_placeholder_type(self.tcx(), vec![span]).emit();
322 self.tcx().mk_const(ty::Const { val: ty::ConstKind::Error, ty })
325 fn projected_ty_from_poly_trait_ref(
329 item_segment: &hir::PathSegment<'_>,
330 poly_trait_ref: ty::PolyTraitRef<'tcx>,
332 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
333 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
341 self.tcx().mk_projection(item_def_id, item_substs)
343 // There are no late-bound regions; we can just ignore the binder.
344 let mut err = struct_span_err!(
348 "cannot extract an associated type from a higher-ranked trait bound \
353 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
355 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
357 hir::ItemKind::Enum(_, generics)
358 | hir::ItemKind::Struct(_, generics)
359 | hir::ItemKind::Union(_, generics) => {
360 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
361 let (lt_sp, sugg) = match &generics.params[..] {
362 [] => (generics.span, format!("<{}>", lt_name)),
364 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
367 let suggestions = vec![
373 // Replace the existing lifetimes with a new named lifetime.
375 .replace_late_bound_regions(&poly_trait_ref, |_| {
376 self.tcx.mk_region(ty::ReEarlyBound(
377 ty::EarlyBoundRegion {
380 name: Symbol::intern(<_name),
389 err.multipart_suggestion(
390 "use a fully qualified path with explicit lifetimes",
392 Applicability::MaybeIncorrect,
398 hir::Node::Item(hir::Item {
400 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
404 | hir::Node::ForeignItem(_)
405 | hir::Node::TraitItem(_)
406 | hir::Node::ImplItem(_) => {
409 "use a fully qualified path with inferred lifetimes",
412 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
413 self.tcx.anonymize_late_bound_regions(&poly_trait_ref).skip_binder(),
416 Applicability::MaybeIncorrect,
426 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
427 // Types in item signatures are not normalized to avoid undue dependencies.
431 fn set_tainted_by_errors(&self) {
432 // There's no obvious place to track this, so just let it go.
435 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
436 // There's no place to record types from signatures?
440 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
441 fn get_new_lifetime_name<'tcx>(
443 poly_trait_ref: ty::PolyTraitRef<'tcx>,
444 generics: &hir::Generics<'tcx>,
446 let existing_lifetimes = tcx
447 .collect_referenced_late_bound_regions(&poly_trait_ref)
450 if let ty::BoundRegion::BrNamed(_, name) = lt {
451 Some(name.as_str().to_string())
456 .chain(generics.params.iter().filter_map(|param| {
457 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
458 Some(param.name.ident().as_str().to_string())
463 .collect::<FxHashSet<String>>();
465 let a_to_z_repeat_n = |n| {
466 (b'a'..=b'z').map(move |c| {
467 let mut s = '\''.to_string();
468 s.extend(std::iter::repeat(char::from(c)).take(n));
473 // If all single char lifetime names are present, we wrap around and double the chars.
474 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
477 /// Returns the predicates defined on `item_def_id` of the form
478 /// `X: Foo` where `X` is the type parameter `def_id`.
479 fn type_param_predicates(
481 (item_def_id, def_id): (DefId, LocalDefId),
482 ) -> ty::GenericPredicates<'_> {
485 // In the AST, bounds can derive from two places. Either
486 // written inline like `<T: Foo>` or in a where-clause like
489 let param_id = tcx.hir().as_local_hir_id(def_id);
490 let param_owner = tcx.hir().ty_param_owner(param_id);
491 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
492 let generics = tcx.generics_of(param_owner_def_id);
493 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
494 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
496 // Don't look for bounds where the type parameter isn't in scope.
497 let parent = if item_def_id == param_owner_def_id.to_def_id() {
500 tcx.generics_of(item_def_id).parent
503 let mut result = parent
505 let icx = ItemCtxt::new(tcx, parent);
506 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id())
508 .unwrap_or_default();
509 let mut extend = None;
511 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id.expect_local());
512 let ast_generics = match tcx.hir().get(item_hir_id) {
513 Node::TraitItem(item) => &item.generics,
515 Node::ImplItem(item) => &item.generics,
517 Node::Item(item) => {
519 ItemKind::Fn(.., ref generics, _)
520 | ItemKind::Impl { ref generics, .. }
521 | ItemKind::TyAlias(_, ref generics)
522 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
523 | ItemKind::Enum(_, ref generics)
524 | ItemKind::Struct(_, ref generics)
525 | ItemKind::Union(_, ref generics) => generics,
526 ItemKind::Trait(_, _, ref generics, ..) => {
527 // Implied `Self: Trait` and supertrait bounds.
528 if param_id == item_hir_id {
529 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
531 Some((identity_trait_ref.without_const().to_predicate(), item.span));
539 Node::ForeignItem(item) => match item.kind {
540 ForeignItemKind::Fn(_, _, ref generics) => generics,
547 let icx = ItemCtxt::new(tcx, item_def_id);
548 let extra_predicates = extend.into_iter().chain(
549 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
551 .filter(|(predicate, _)| match predicate {
552 ty::PredicateKind::Trait(ref data, _) => {
553 data.skip_binder().self_ty().is_param(index)
559 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
563 impl ItemCtxt<'tcx> {
564 /// Finds bounds from `hir::Generics`. This requires scanning through the
565 /// AST. We do this to avoid having to convert *all* the bounds, which
566 /// would create artificial cycles. Instead, we can only convert the
567 /// bounds for a type parameter `X` if `X::Foo` is used.
568 fn type_parameter_bounds_in_generics(
570 ast_generics: &'tcx hir::Generics<'tcx>,
571 param_id: hir::HirId,
573 only_self_bounds: OnlySelfBounds,
574 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
575 let constness = self.default_constness_for_trait_bounds();
576 let from_ty_params = ast_generics
579 .filter_map(|param| match param.kind {
580 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
583 .flat_map(|bounds| bounds.iter())
584 .flat_map(|b| predicates_from_bound(self, ty, b, constness));
586 let from_where_clauses = ast_generics
590 .filter_map(|wp| match *wp {
591 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
595 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
597 } else if !only_self_bounds.0 {
598 Some(self.to_ty(&bp.bounded_ty))
602 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
604 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b, constness));
606 from_ty_params.chain(from_where_clauses).collect()
610 /// Tests whether this is the AST for a reference to the type
611 /// parameter with ID `param_id`. We use this so as to avoid running
612 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
613 /// conversion of the type to avoid inducing unnecessary cycles.
614 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
615 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
617 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
618 def_id == tcx.hir().local_def_id(param_id).to_def_id()
627 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::HirId) {
628 let it = tcx.hir().expect_item(item_id);
629 debug!("convert: item {} with id {}", it.ident, it.hir_id);
630 let def_id = tcx.hir().local_def_id(item_id);
632 // These don't define types.
633 hir::ItemKind::ExternCrate(_)
634 | hir::ItemKind::Use(..)
635 | hir::ItemKind::Mod(_)
636 | hir::ItemKind::GlobalAsm(_) => {}
637 hir::ItemKind::ForeignMod(ref foreign_mod) => {
638 for item in foreign_mod.items {
639 let def_id = tcx.hir().local_def_id(item.hir_id);
640 tcx.ensure().generics_of(def_id);
641 tcx.ensure().type_of(def_id);
642 tcx.ensure().predicates_of(def_id);
643 if let hir::ForeignItemKind::Fn(..) = item.kind {
644 tcx.ensure().fn_sig(def_id);
648 hir::ItemKind::Enum(ref enum_definition, _) => {
649 tcx.ensure().generics_of(def_id);
650 tcx.ensure().type_of(def_id);
651 tcx.ensure().predicates_of(def_id);
652 convert_enum_variant_types(tcx, def_id.to_def_id(), &enum_definition.variants);
654 hir::ItemKind::Impl { .. } => {
655 tcx.ensure().generics_of(def_id);
656 tcx.ensure().type_of(def_id);
657 tcx.ensure().impl_trait_ref(def_id);
658 tcx.ensure().predicates_of(def_id);
660 hir::ItemKind::Trait(..) => {
661 tcx.ensure().generics_of(def_id);
662 tcx.ensure().trait_def(def_id);
663 tcx.at(it.span).super_predicates_of(def_id);
664 tcx.ensure().predicates_of(def_id);
666 hir::ItemKind::TraitAlias(..) => {
667 tcx.ensure().generics_of(def_id);
668 tcx.at(it.span).super_predicates_of(def_id);
669 tcx.ensure().predicates_of(def_id);
671 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
672 tcx.ensure().generics_of(def_id);
673 tcx.ensure().type_of(def_id);
674 tcx.ensure().predicates_of(def_id);
676 for f in struct_def.fields() {
677 let def_id = tcx.hir().local_def_id(f.hir_id);
678 tcx.ensure().generics_of(def_id);
679 tcx.ensure().type_of(def_id);
680 tcx.ensure().predicates_of(def_id);
683 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
684 convert_variant_ctor(tcx, ctor_hir_id);
688 // Desugared from `impl Trait`, so visited by the function's return type.
689 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
691 hir::ItemKind::OpaqueTy(..)
692 | hir::ItemKind::TyAlias(..)
693 | hir::ItemKind::Static(..)
694 | hir::ItemKind::Const(..)
695 | hir::ItemKind::Fn(..) => {
696 tcx.ensure().generics_of(def_id);
697 tcx.ensure().type_of(def_id);
698 tcx.ensure().predicates_of(def_id);
699 if let hir::ItemKind::Fn(..) = it.kind {
700 tcx.ensure().fn_sig(def_id);
706 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
707 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
708 let def_id = tcx.hir().local_def_id(trait_item.hir_id);
709 tcx.ensure().generics_of(def_id);
711 match trait_item.kind {
712 hir::TraitItemKind::Fn(..) => {
713 tcx.ensure().type_of(def_id);
714 tcx.ensure().fn_sig(def_id);
717 hir::TraitItemKind::Const(.., Some(_)) => {
718 tcx.ensure().type_of(def_id);
721 hir::TraitItemKind::Const(..) | hir::TraitItemKind::Type(_, Some(_)) => {
722 tcx.ensure().type_of(def_id);
723 // Account for `const C: _;` and `type T = _;`.
724 let mut visitor = PlaceholderHirTyCollector::default();
725 visitor.visit_trait_item(trait_item);
726 placeholder_type_error(tcx, DUMMY_SP, &[], visitor.0, false);
729 hir::TraitItemKind::Type(_, None) => {}
732 tcx.ensure().predicates_of(def_id);
735 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
736 let def_id = tcx.hir().local_def_id(impl_item_id);
737 tcx.ensure().generics_of(def_id);
738 tcx.ensure().type_of(def_id);
739 tcx.ensure().predicates_of(def_id);
740 let impl_item = tcx.hir().expect_impl_item(impl_item_id);
741 match impl_item.kind {
742 hir::ImplItemKind::Fn(..) => {
743 tcx.ensure().fn_sig(def_id);
745 hir::ImplItemKind::TyAlias(_) | hir::ImplItemKind::OpaqueTy(_) => {
746 // Account for `type T = _;`
747 let mut visitor = PlaceholderHirTyCollector::default();
748 visitor.visit_impl_item(impl_item);
749 placeholder_type_error(tcx, DUMMY_SP, &[], visitor.0, false);
751 hir::ImplItemKind::Const(..) => {}
755 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
756 let def_id = tcx.hir().local_def_id(ctor_id);
757 tcx.ensure().generics_of(def_id);
758 tcx.ensure().type_of(def_id);
759 tcx.ensure().predicates_of(def_id);
762 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
763 let def = tcx.adt_def(def_id);
764 let repr_type = def.repr.discr_type();
765 let initial = repr_type.initial_discriminant(tcx);
766 let mut prev_discr = None::<Discr<'_>>;
768 // fill the discriminant values and field types
769 for variant in variants {
770 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
772 if let Some(ref e) = variant.disr_expr {
773 let expr_did = tcx.hir().local_def_id(e.hir_id);
774 def.eval_explicit_discr(tcx, expr_did.to_def_id())
775 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
778 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
781 format!("overflowed on value after {}", prev_discr.unwrap()),
784 "explicitly set `{} = {}` if that is desired outcome",
785 variant.ident, wrapped_discr
790 .unwrap_or(wrapped_discr),
793 for f in variant.data.fields() {
794 let def_id = tcx.hir().local_def_id(f.hir_id);
795 tcx.ensure().generics_of(def_id);
796 tcx.ensure().type_of(def_id);
797 tcx.ensure().predicates_of(def_id);
800 // Convert the ctor, if any. This also registers the variant as
802 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
803 convert_variant_ctor(tcx, ctor_hir_id);
810 variant_did: Option<LocalDefId>,
811 ctor_did: Option<LocalDefId>,
813 discr: ty::VariantDiscr,
814 def: &hir::VariantData<'_>,
815 adt_kind: ty::AdtKind,
816 parent_did: LocalDefId,
817 ) -> ty::VariantDef {
818 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
819 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did));
824 let fid = tcx.hir().local_def_id(f.hir_id);
825 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
826 if let Some(prev_span) = dup_span {
831 "field `{}` is already declared",
834 .span_label(f.span, "field already declared")
835 .span_label(prev_span, format!("`{}` first declared here", f.ident))
838 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
842 did: fid.to_def_id(),
844 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
848 let recovered = match def {
849 hir::VariantData::Struct(_, r) => *r,
855 variant_did.map(LocalDefId::to_def_id),
856 ctor_did.map(LocalDefId::to_def_id),
859 CtorKind::from_hir(def),
861 parent_did.to_def_id(),
866 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
869 let def_id = def_id.expect_local();
870 let hir_id = tcx.hir().as_local_hir_id(def_id);
871 let item = match tcx.hir().get(hir_id) {
872 Node::Item(item) => item,
876 let repr = ReprOptions::new(tcx, def_id.to_def_id());
877 let (kind, variants) = match item.kind {
878 ItemKind::Enum(ref def, _) => {
879 let mut distance_from_explicit = 0;
884 let variant_did = Some(tcx.hir().local_def_id(v.id));
886 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
888 let discr = if let Some(ref e) = v.disr_expr {
889 distance_from_explicit = 0;
890 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
892 ty::VariantDiscr::Relative(distance_from_explicit)
894 distance_from_explicit += 1;
909 (AdtKind::Enum, variants)
911 ItemKind::Struct(ref def, _) => {
912 let variant_did = None::<LocalDefId>;
913 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
915 let variants = std::iter::once(convert_variant(
920 ty::VariantDiscr::Relative(0),
927 (AdtKind::Struct, variants)
929 ItemKind::Union(ref def, _) => {
930 let variant_did = None;
931 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
933 let variants = std::iter::once(convert_variant(
938 ty::VariantDiscr::Relative(0),
945 (AdtKind::Union, variants)
949 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
952 /// Ensures that the super-predicates of the trait with a `DefId`
953 /// of `trait_def_id` are converted and stored. This also ensures that
954 /// the transitive super-predicates are converted.
955 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
956 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
957 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id.expect_local());
959 let item = match tcx.hir().get(trait_hir_id) {
960 Node::Item(item) => item,
961 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
964 let (generics, bounds) = match item.kind {
965 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
966 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
967 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
970 let icx = ItemCtxt::new(tcx, trait_def_id);
972 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
973 let self_param_ty = tcx.types.self_param;
975 AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
977 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
979 // Convert any explicit superbounds in the where-clause,
980 // e.g., `trait Foo where Self: Bar`.
981 // In the case of trait aliases, however, we include all bounds in the where-clause,
982 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
983 // as one of its "superpredicates".
984 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
985 let superbounds2 = icx.type_parameter_bounds_in_generics(
989 OnlySelfBounds(!is_trait_alias),
992 // Combine the two lists to form the complete set of superbounds:
993 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
995 // Now require that immediate supertraits are converted,
996 // which will, in turn, reach indirect supertraits.
997 for &(pred, span) in superbounds {
998 debug!("superbound: {:?}", pred);
999 if let ty::PredicateKind::Trait(bound, _) = pred {
1000 tcx.at(span).super_predicates_of(bound.def_id());
1004 ty::GenericPredicates { parent: None, predicates: superbounds }
1007 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1008 let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
1009 let item = tcx.hir().expect_item(hir_id);
1011 let (is_auto, unsafety) = match item.kind {
1012 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
1013 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
1014 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1017 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1018 if paren_sugar && !tcx.features().unboxed_closures {
1022 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1023 which traits can use parenthetical notation",
1025 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1029 let is_marker = tcx.has_attr(def_id, sym::marker);
1030 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1031 ty::trait_def::TraitSpecializationKind::Marker
1032 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1033 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1035 ty::trait_def::TraitSpecializationKind::None
1037 let def_path_hash = tcx.def_path_hash(def_id);
1038 ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, spec_kind, def_path_hash)
1041 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1042 struct LateBoundRegionsDetector<'tcx> {
1044 outer_index: ty::DebruijnIndex,
1045 has_late_bound_regions: Option<Span>,
1048 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1049 type Map = intravisit::ErasedMap<'tcx>;
1051 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1052 NestedVisitorMap::None
1055 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1056 if self.has_late_bound_regions.is_some() {
1060 hir::TyKind::BareFn(..) => {
1061 self.outer_index.shift_in(1);
1062 intravisit::walk_ty(self, ty);
1063 self.outer_index.shift_out(1);
1065 _ => intravisit::walk_ty(self, ty),
1069 fn visit_poly_trait_ref(
1071 tr: &'tcx hir::PolyTraitRef<'tcx>,
1072 m: hir::TraitBoundModifier,
1074 if self.has_late_bound_regions.is_some() {
1077 self.outer_index.shift_in(1);
1078 intravisit::walk_poly_trait_ref(self, tr, m);
1079 self.outer_index.shift_out(1);
1082 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1083 if self.has_late_bound_regions.is_some() {
1087 match self.tcx.named_region(lt.hir_id) {
1088 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1090 rl::Region::LateBound(debruijn, _, _) | rl::Region::LateBoundAnon(debruijn, _),
1091 ) if debruijn < self.outer_index => {}
1093 rl::Region::LateBound(..)
1094 | rl::Region::LateBoundAnon(..)
1095 | rl::Region::Free(..),
1098 self.has_late_bound_regions = Some(lt.span);
1104 fn has_late_bound_regions<'tcx>(
1106 generics: &'tcx hir::Generics<'tcx>,
1107 decl: &'tcx hir::FnDecl<'tcx>,
1109 let mut visitor = LateBoundRegionsDetector {
1111 outer_index: ty::INNERMOST,
1112 has_late_bound_regions: None,
1114 for param in generics.params {
1115 if let GenericParamKind::Lifetime { .. } = param.kind {
1116 if tcx.is_late_bound(param.hir_id) {
1117 return Some(param.span);
1121 visitor.visit_fn_decl(decl);
1122 visitor.has_late_bound_regions
1126 Node::TraitItem(item) => match item.kind {
1127 hir::TraitItemKind::Fn(ref sig, _) => {
1128 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1132 Node::ImplItem(item) => match item.kind {
1133 hir::ImplItemKind::Fn(ref sig, _) => {
1134 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1138 Node::ForeignItem(item) => match item.kind {
1139 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
1140 has_late_bound_regions(tcx, generics, fn_decl)
1144 Node::Item(item) => match item.kind {
1145 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1146 has_late_bound_regions(tcx, generics, &sig.decl)
1154 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1157 let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
1159 let node = tcx.hir().get(hir_id);
1160 let parent_def_id = match node {
1162 | Node::TraitItem(_)
1165 | Node::Field(_) => {
1166 let parent_id = tcx.hir().get_parent_item(hir_id);
1167 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1169 // FIXME(#43408) always enable this once `lazy_normalization` is
1170 // stable enough and does not need a feature gate anymore.
1171 Node::AnonConst(_) => {
1172 let parent_id = tcx.hir().get_parent_item(hir_id);
1173 let parent_def_id = tcx.hir().local_def_id(parent_id);
1175 // HACK(eddyb) this provides the correct generics when
1176 // `feature(const_generics)` is enabled, so that const expressions
1177 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1178 if tcx.lazy_normalization() {
1179 Some(parent_def_id.to_def_id())
1181 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1183 // HACK(eddyb) this provides the correct generics for repeat
1184 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1185 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1186 // as they shouldn't be able to cause query cycle errors.
1187 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1188 | Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1189 if constant.hir_id == hir_id =>
1191 Some(parent_def_id.to_def_id())
1198 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1199 Some(tcx.closure_base_def_id(def_id))
1201 Node::Item(item) => match item.kind {
1202 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => {
1203 impl_trait_fn.or_else(|| {
1204 let parent_id = tcx.hir().get_parent_item(hir_id);
1205 if parent_id != hir_id && parent_id != CRATE_HIR_ID {
1206 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1207 // If this 'impl Trait' is nested inside another 'impl Trait'
1208 // (e.g. `impl Foo<MyType = impl Bar<A>>`), we need to use the 'parent'
1209 // 'impl Trait' for its generic parameters, since we can reference them
1210 // from the 'child' 'impl Trait'
1211 if let Node::Item(hir::Item { kind: ItemKind::OpaqueTy(..), .. }) =
1212 tcx.hir().get(parent_id)
1214 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1228 let mut opt_self = None;
1229 let mut allow_defaults = false;
1231 let no_generics = hir::Generics::empty();
1232 let ast_generics = match node {
1233 Node::TraitItem(item) => &item.generics,
1235 Node::ImplItem(item) => &item.generics,
1237 Node::Item(item) => {
1239 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl { ref generics, .. } => generics,
1241 ItemKind::TyAlias(_, ref generics)
1242 | ItemKind::Enum(_, ref generics)
1243 | ItemKind::Struct(_, ref generics)
1244 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1245 | ItemKind::Union(_, ref generics) => {
1246 allow_defaults = true;
1250 ItemKind::Trait(_, _, ref generics, ..)
1251 | ItemKind::TraitAlias(ref generics, ..) => {
1252 // Add in the self type parameter.
1254 // Something of a hack: use the node id for the trait, also as
1255 // the node id for the Self type parameter.
1256 let param_id = item.hir_id;
1258 opt_self = Some(ty::GenericParamDef {
1260 name: kw::SelfUpper,
1261 def_id: tcx.hir().local_def_id(param_id).to_def_id(),
1262 pure_wrt_drop: false,
1263 kind: ty::GenericParamDefKind::Type {
1265 object_lifetime_default: rl::Set1::Empty,
1270 allow_defaults = true;
1278 Node::ForeignItem(item) => match item.kind {
1279 ForeignItemKind::Static(..) => &no_generics,
1280 ForeignItemKind::Fn(_, _, ref generics) => generics,
1281 ForeignItemKind::Type => &no_generics,
1287 let has_self = opt_self.is_some();
1288 let mut parent_has_self = false;
1289 let mut own_start = has_self as u32;
1290 let parent_count = parent_def_id.map_or(0, |def_id| {
1291 let generics = tcx.generics_of(def_id);
1292 assert_eq!(has_self, false);
1293 parent_has_self = generics.has_self;
1294 own_start = generics.count() as u32;
1295 generics.parent_count + generics.params.len()
1298 let mut params: Vec<_> = opt_self.into_iter().collect();
1300 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1301 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1302 name: param.name.ident().name,
1303 index: own_start + i as u32,
1304 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1305 pure_wrt_drop: param.pure_wrt_drop,
1306 kind: ty::GenericParamDefKind::Lifetime,
1309 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1311 // Now create the real type and const parameters.
1312 let type_start = own_start - has_self as u32 + params.len() as u32;
1315 // FIXME(const_generics): a few places in the compiler expect generic params
1316 // to be in the order lifetimes, then type params, then const params.
1318 // To prevent internal errors in case const parameters are supplied before
1319 // type parameters we first add all type params, then all const params.
1320 params.extend(ast_generics.params.iter().filter_map(|param| {
1321 if let GenericParamKind::Type { ref default, synthetic, .. } = param.kind {
1322 if !allow_defaults && default.is_some() {
1323 if !tcx.features().default_type_parameter_fallback {
1324 tcx.struct_span_lint_hir(
1325 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1330 "defaults for type parameters are only allowed in \
1331 `struct`, `enum`, `type`, or `trait` definitions.",
1339 let kind = ty::GenericParamDefKind::Type {
1340 has_default: default.is_some(),
1341 object_lifetime_default: object_lifetime_defaults
1343 .map_or(rl::Set1::Empty, |o| o[i]),
1347 let param_def = ty::GenericParamDef {
1348 index: type_start + i as u32,
1349 name: param.name.ident().name,
1350 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1351 pure_wrt_drop: param.pure_wrt_drop,
1361 params.extend(ast_generics.params.iter().filter_map(|param| {
1362 if let GenericParamKind::Const { .. } = param.kind {
1363 let param_def = ty::GenericParamDef {
1364 index: type_start + i as u32,
1365 name: param.name.ident().name,
1366 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1367 pure_wrt_drop: param.pure_wrt_drop,
1368 kind: ty::GenericParamDefKind::Const,
1377 // provide junk type parameter defs - the only place that
1378 // cares about anything but the length is instantiation,
1379 // and we don't do that for closures.
1380 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1381 let dummy_args = if gen.is_some() {
1382 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1384 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1387 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1388 index: type_start + i as u32,
1389 name: Symbol::intern(arg),
1391 pure_wrt_drop: false,
1392 kind: ty::GenericParamDefKind::Type {
1394 object_lifetime_default: rl::Set1::Empty,
1400 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1403 parent: parent_def_id,
1406 param_def_id_to_index,
1407 has_self: has_self || parent_has_self,
1408 has_late_bound_regions: has_late_bound_regions(tcx, node),
1412 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1415 .filter_map(|arg| match arg {
1416 hir::GenericArg::Type(ty) => Some(ty),
1419 .any(is_suggestable_infer_ty)
1422 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1423 /// use inference to provide suggestions for the appropriate type if possible.
1424 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1428 Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
1429 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1430 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1431 Def(_, generic_args) => are_suggestable_generic_args(generic_args),
1432 Path(hir::QPath::TypeRelative(ty, segment)) => {
1433 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.generic_args().args)
1435 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1436 ty_opt.map_or(false, is_suggestable_infer_ty)
1439 .any(|segment| are_suggestable_generic_args(segment.generic_args().args))
1445 pub fn get_infer_ret_ty(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1446 if let hir::FnRetTy::Return(ref ty) = output {
1447 if is_suggestable_infer_ty(ty) {
1454 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1455 use rustc_hir::Node::*;
1458 let def_id = def_id.expect_local();
1459 let hir_id = tcx.hir().as_local_hir_id(def_id);
1461 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1463 match tcx.hir().get(hir_id) {
1464 TraitItem(hir::TraitItem {
1465 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1470 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1471 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1472 match get_infer_ret_ty(&sig.decl.output) {
1474 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1475 let mut visitor = PlaceholderHirTyCollector::default();
1476 visitor.visit_ty(ty);
1477 let mut diag = bad_placeholder_type(tcx, visitor.0);
1478 let ret_ty = fn_sig.output();
1479 if ret_ty != tcx.types.err {
1480 diag.span_suggestion(
1482 "replace with the correct return type",
1484 Applicability::MaybeIncorrect,
1488 ty::Binder::bind(fn_sig)
1490 None => AstConv::ty_of_fn(
1492 sig.header.unsafety,
1501 TraitItem(hir::TraitItem {
1502 kind: TraitItemKind::Fn(FnSig { header, decl }, _),
1507 AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl, &generics, Some(ident.span))
1510 ForeignItem(&hir::ForeignItem {
1511 kind: ForeignItemKind::Fn(ref fn_decl, _, _),
1515 let abi = tcx.hir().get_foreign_abi(hir_id);
1516 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1519 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1520 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id).to_def_id());
1522 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1523 ty::Binder::bind(tcx.mk_fn_sig(
1527 hir::Unsafety::Normal,
1532 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1533 // Closure signatures are not like other function
1534 // signatures and cannot be accessed through `fn_sig`. For
1535 // example, a closure signature excludes the `self`
1536 // argument. In any case they are embedded within the
1537 // closure type as part of the `ClosureSubsts`.
1539 // To get the signature of a closure, you should use the
1540 // `sig` method on the `ClosureSubsts`:
1542 // substs.as_closure().sig(def_id, tcx)
1544 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1549 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1554 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1555 let icx = ItemCtxt::new(tcx, def_id);
1557 let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
1558 match tcx.hir().expect_item(hir_id).kind {
1559 hir::ItemKind::Impl { ref of_trait, .. } => of_trait.as_ref().map(|ast_trait_ref| {
1560 let selfty = tcx.type_of(def_id);
1561 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1567 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1568 let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
1569 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1570 let item = tcx.hir().expect_item(hir_id);
1572 hir::ItemKind::Impl { polarity: hir::ImplPolarity::Negative(span), of_trait, .. } => {
1573 if is_rustc_reservation {
1574 let span = span.to(of_trait.as_ref().map(|t| t.path.span).unwrap_or(*span));
1575 tcx.sess.span_err(span, "reservation impls can't be negative");
1577 ty::ImplPolarity::Negative
1579 hir::ItemKind::Impl { polarity: hir::ImplPolarity::Positive, of_trait: None, .. } => {
1580 if is_rustc_reservation {
1581 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1583 ty::ImplPolarity::Positive
1585 hir::ItemKind::Impl {
1586 polarity: hir::ImplPolarity::Positive, of_trait: Some(_), ..
1588 if is_rustc_reservation {
1589 ty::ImplPolarity::Reservation
1591 ty::ImplPolarity::Positive
1594 ref item => bug!("impl_polarity: {:?} not an impl", item),
1598 /// Returns the early-bound lifetimes declared in this generics
1599 /// listing. For anything other than fns/methods, this is just all
1600 /// the lifetimes that are declared. For fns or methods, we have to
1601 /// screen out those that do not appear in any where-clauses etc using
1602 /// `resolve_lifetime::early_bound_lifetimes`.
1603 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1605 generics: &'a hir::Generics<'a>,
1606 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1607 generics.params.iter().filter(move |param| match param.kind {
1608 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1613 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1614 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1615 /// inferred constraints concerning which regions outlive other regions.
1616 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1617 debug!("predicates_defined_on({:?})", def_id);
1618 let mut result = tcx.explicit_predicates_of(def_id);
1619 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1620 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1621 if !inferred_outlives.is_empty() {
1623 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1624 def_id, inferred_outlives,
1626 if result.predicates.is_empty() {
1627 result.predicates = inferred_outlives;
1629 result.predicates = tcx
1631 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1634 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1638 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1639 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1640 /// `Self: Trait` predicates for traits.
1641 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1642 let mut result = tcx.predicates_defined_on(def_id);
1644 if tcx.is_trait(def_id) {
1645 // For traits, add `Self: Trait` predicate. This is
1646 // not part of the predicates that a user writes, but it
1647 // is something that one must prove in order to invoke a
1648 // method or project an associated type.
1650 // In the chalk setup, this predicate is not part of the
1651 // "predicates" for a trait item. But it is useful in
1652 // rustc because if you directly (e.g.) invoke a trait
1653 // method like `Trait::method(...)`, you must naturally
1654 // prove that the trait applies to the types that were
1655 // used, and adding the predicate into this list ensures
1656 // that this is done.
1657 let span = tcx.sess.source_map().guess_head_span(tcx.def_span(def_id));
1659 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
1660 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(),
1664 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1668 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1669 /// N.B., this does not include any implied/inferred constraints.
1670 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1673 debug!("explicit_predicates_of(def_id={:?})", def_id);
1675 /// A data structure with unique elements, which preserves order of insertion.
1676 /// Preserving the order of insertion is important here so as not to break
1677 /// compile-fail UI tests.
1678 // FIXME(eddyb) just use `IndexSet` from `indexmap`.
1679 struct UniquePredicates<'tcx> {
1680 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1681 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1684 impl<'tcx> UniquePredicates<'tcx> {
1686 UniquePredicates { predicates: vec![], uniques: FxHashSet::default() }
1689 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
1690 if self.uniques.insert(value) {
1691 self.predicates.push(value);
1695 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
1702 let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
1703 let node = tcx.hir().get(hir_id);
1705 let mut is_trait = None;
1706 let mut is_default_impl_trait = None;
1708 let icx = ItemCtxt::new(tcx, def_id);
1709 let constness = icx.default_constness_for_trait_bounds();
1711 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
1713 let mut predicates = UniquePredicates::new();
1715 let ast_generics = match node {
1716 Node::TraitItem(item) => &item.generics,
1718 Node::ImplItem(item) => match item.kind {
1719 ImplItemKind::OpaqueTy(ref bounds) => {
1720 ty::print::with_no_queries(|| {
1721 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1722 let opaque_ty = tcx.mk_opaque(def_id, substs);
1724 "explicit_predicates_of({:?}): created opaque type {:?}",
1728 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
1729 let bounds = AstConv::compute_bounds(
1733 SizedByDefault::Yes,
1734 tcx.def_span(def_id),
1737 predicates.extend(bounds.predicates(tcx, opaque_ty));
1741 _ => &item.generics,
1744 Node::Item(item) => {
1746 ItemKind::Impl { defaultness, ref generics, .. } => {
1747 if defaultness.is_default() {
1748 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1752 ItemKind::Fn(.., ref generics, _)
1753 | ItemKind::TyAlias(_, ref generics)
1754 | ItemKind::Enum(_, ref generics)
1755 | ItemKind::Struct(_, ref generics)
1756 | ItemKind::Union(_, ref generics) => generics,
1758 ItemKind::Trait(_, _, ref generics, .., items) => {
1759 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
1762 ItemKind::TraitAlias(ref generics, _) => {
1763 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &[]));
1766 ItemKind::OpaqueTy(OpaqueTy {
1772 let bounds_predicates = ty::print::with_no_queries(|| {
1773 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1774 let opaque_ty = tcx.mk_opaque(def_id, substs);
1776 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
1777 let bounds = AstConv::compute_bounds(
1781 SizedByDefault::Yes,
1782 tcx.def_span(def_id),
1785 bounds.predicates(tcx, opaque_ty)
1787 if impl_trait_fn.is_some() {
1789 return ty::GenericPredicates {
1791 predicates: tcx.arena.alloc_from_iter(bounds_predicates),
1794 // named opaque types
1795 predicates.extend(bounds_predicates);
1804 Node::ForeignItem(item) => match item.kind {
1805 ForeignItemKind::Static(..) => NO_GENERICS,
1806 ForeignItemKind::Fn(_, _, ref generics) => generics,
1807 ForeignItemKind::Type => NO_GENERICS,
1813 let generics = tcx.generics_of(def_id);
1814 let parent_count = generics.parent_count as u32;
1815 let has_own_self = generics.has_self && parent_count == 0;
1817 // Below we'll consider the bounds on the type parameters (including `Self`)
1818 // and the explicit where-clauses, but to get the full set of predicates
1819 // on a trait we need to add in the supertrait bounds and bounds found on
1820 // associated types.
1821 if let Some((_trait_ref, _)) = is_trait {
1822 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
1825 // In default impls, we can assume that the self type implements
1826 // the trait. So in:
1828 // default impl Foo for Bar { .. }
1830 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
1831 // (see below). Recall that a default impl is not itself an impl, but rather a
1832 // set of defaults that can be incorporated into another impl.
1833 if let Some(trait_ref) = is_default_impl_trait {
1835 trait_ref.to_poly_trait_ref().without_const().to_predicate(),
1836 tcx.def_span(def_id),
1840 // Collect the region predicates that were declared inline as
1841 // well. In the case of parameters declared on a fn or method, we
1842 // have to be careful to only iterate over early-bound regions.
1843 let mut index = parent_count + has_own_self as u32;
1844 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
1845 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
1846 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1848 name: param.name.ident().name,
1853 GenericParamKind::Lifetime { .. } => {
1854 param.bounds.iter().for_each(|bound| match bound {
1855 hir::GenericBound::Outlives(lt) => {
1856 let bound = AstConv::ast_region_to_region(&icx, <, None);
1857 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
1858 predicates.push((outlives.to_predicate(), lt.span));
1867 // Collect the predicates that were written inline by the user on each
1868 // type parameter (e.g., `<T: Foo>`).
1869 for param in ast_generics.params {
1870 if let GenericParamKind::Type { .. } = param.kind {
1871 let name = param.name.ident().name;
1872 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
1875 let sized = SizedByDefault::Yes;
1876 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
1877 predicates.extend(bounds.predicates(tcx, param_ty));
1881 // Add in the bounds that appear in the where-clause.
1882 let where_clause = &ast_generics.where_clause;
1883 for predicate in where_clause.predicates {
1885 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
1886 let ty = icx.to_ty(&bound_pred.bounded_ty);
1888 // Keep the type around in a dummy predicate, in case of no bounds.
1889 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
1890 // is still checked for WF.
1891 if bound_pred.bounds.is_empty() {
1892 if let ty::Param(_) = ty.kind {
1893 // This is a `where T:`, which can be in the HIR from the
1894 // transformation that moves `?Sized` to `T`'s declaration.
1895 // We can skip the predicate because type parameters are
1896 // trivially WF, but also we *should*, to avoid exposing
1897 // users who never wrote `where Type:,` themselves, to
1898 // compiler/tooling bugs from not handling WF predicates.
1900 let span = bound_pred.bounded_ty.span;
1901 let re_root_empty = tcx.lifetimes.re_root_empty;
1902 let predicate = ty::OutlivesPredicate(ty, re_root_empty);
1904 ty::PredicateKind::TypeOutlives(ty::Binder::dummy(predicate)),
1910 for bound in bound_pred.bounds.iter() {
1912 &hir::GenericBound::Trait(ref poly_trait_ref, modifier) => {
1913 let constness = match modifier {
1914 hir::TraitBoundModifier::MaybeConst => hir::Constness::NotConst,
1915 hir::TraitBoundModifier::None => constness,
1916 hir::TraitBoundModifier::Maybe => bug!("this wasn't handled"),
1919 let mut bounds = Bounds::default();
1920 let _ = AstConv::instantiate_poly_trait_ref(
1927 predicates.extend(bounds.predicates(tcx, ty));
1930 &hir::GenericBound::Outlives(ref lifetime) => {
1931 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
1932 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
1933 predicates.push((ty::PredicateKind::TypeOutlives(pred), lifetime.span))
1939 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
1940 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
1941 predicates.extend(region_pred.bounds.iter().map(|bound| {
1942 let (r2, span) = match bound {
1943 hir::GenericBound::Outlives(lt) => {
1944 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
1948 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
1950 (ty::PredicateKind::RegionOutlives(pred), span)
1954 &hir::WherePredicate::EqPredicate(..) => {
1960 // Add predicates from associated type bounds.
1961 if let Some((self_trait_ref, trait_items)) = is_trait {
1962 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
1963 associated_item_predicates(tcx, def_id, self_trait_ref, trait_item_ref)
1967 let mut predicates = predicates.predicates;
1969 // Subtle: before we store the predicates into the tcx, we
1970 // sort them so that predicates like `T: Foo<Item=U>` come
1971 // before uses of `U`. This avoids false ambiguity errors
1972 // in trait checking. See `setup_constraining_predicates`
1974 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
1975 let self_ty = tcx.type_of(def_id);
1976 let trait_ref = tcx.impl_trait_ref(def_id);
1977 cgp::setup_constraining_predicates(
1981 &mut cgp::parameters_for_impl(self_ty, trait_ref),
1985 let result = ty::GenericPredicates {
1986 parent: generics.parent,
1987 predicates: tcx.arena.alloc_from_iter(predicates),
1989 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
1993 fn associated_item_predicates(
1996 self_trait_ref: ty::TraitRef<'tcx>,
1997 trait_item_ref: &hir::TraitItemRef,
1998 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
1999 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2000 let item_def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
2001 let bounds = match trait_item.kind {
2002 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2003 _ => return Vec::new(),
2006 let is_gat = !tcx.generics_of(item_def_id).params.is_empty();
2008 let mut had_error = false;
2010 let mut unimplemented_error = |arg_kind: &str| {
2015 &format!("{}-generic associated types are not yet implemented", arg_kind),
2018 "for more information, see issue #44265 \
2019 <https://github.com/rust-lang/rust/issues/44265> for more information",
2026 let mk_bound_param = |param: &ty::GenericParamDef, _: &_| {
2028 ty::GenericParamDefKind::Lifetime => tcx
2029 .mk_region(ty::RegionKind::ReLateBound(
2031 ty::BoundRegion::BrNamed(param.def_id, param.name),
2034 // FIXME(generic_associated_types): Use bound types and constants
2035 // once they are handled by the trait system.
2036 ty::GenericParamDefKind::Type { .. } => {
2037 unimplemented_error("type");
2038 tcx.types.err.into()
2040 ty::GenericParamDefKind::Const => {
2041 unimplemented_error("const");
2042 tcx.mk_const(ty::Const { val: ty::ConstKind::Error, ty: tcx.type_of(param.def_id) })
2048 let bound_substs = if is_gat {
2051 // trait X<'a, B, const C: usize> {
2052 // type T<'d, E, const F: usize>: Default;
2055 // We need to create predicates on the trait:
2057 // for<'d, E, const F: usize>
2058 // <Self as X<'a, B, const C: usize>>::T<'d, E, const F: usize>: Sized + Default
2060 // We substitute escaping bound parameters for the generic
2061 // arguments to the associated type which are then bound by
2062 // the `Binder` around the the predicate.
2064 // FIXME(generic_associated_types): Currently only lifetimes are handled.
2065 self_trait_ref.substs.extend_to(tcx, item_def_id.to_def_id(), mk_bound_param)
2067 self_trait_ref.substs
2071 tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id).to_def_id(), bound_substs);
2073 let bounds = AstConv::compute_bounds(
2074 &ItemCtxt::new(tcx, def_id),
2077 SizedByDefault::Yes,
2081 let predicates = bounds.predicates(tcx, assoc_ty);
2084 // We use shifts to get the regions that we're substituting to
2085 // be bound by the binders in the `Predicate`s rather that
2087 let shifted_in = ty::fold::shift_vars(tcx, &predicates, 1);
2088 let substituted = shifted_in.subst(tcx, bound_substs);
2089 ty::fold::shift_out_vars(tcx, &substituted, 1)
2095 /// Converts a specific `GenericBound` from the AST into a set of
2096 /// predicates that apply to the self type. A vector is returned
2097 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2098 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2099 /// and `<T as Bar>::X == i32`).
2100 fn predicates_from_bound<'tcx>(
2101 astconv: &dyn AstConv<'tcx>,
2103 bound: &'tcx hir::GenericBound<'tcx>,
2104 constness: hir::Constness,
2105 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2107 hir::GenericBound::Trait(ref tr, modifier) => {
2108 let constness = match modifier {
2109 hir::TraitBoundModifier::Maybe => return vec![],
2110 hir::TraitBoundModifier::MaybeConst => hir::Constness::NotConst,
2111 hir::TraitBoundModifier::None => constness,
2114 let mut bounds = Bounds::default();
2115 let _ = astconv.instantiate_poly_trait_ref(tr, constness, param_ty, &mut bounds);
2116 bounds.predicates(astconv.tcx(), param_ty)
2118 hir::GenericBound::Outlives(ref lifetime) => {
2119 let region = astconv.ast_region_to_region(lifetime, None);
2120 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2121 vec![(ty::PredicateKind::TypeOutlives(pred), lifetime.span)]
2126 fn compute_sig_of_foreign_fn_decl<'tcx>(
2129 decl: &'tcx hir::FnDecl<'tcx>,
2132 ) -> ty::PolyFnSig<'tcx> {
2133 let unsafety = if abi == abi::Abi::RustIntrinsic {
2134 intrinsic_operation_unsafety(&tcx.item_name(def_id).as_str())
2136 hir::Unsafety::Unsafe
2138 let fty = AstConv::ty_of_fn(
2139 &ItemCtxt::new(tcx, def_id),
2143 &hir::Generics::empty(),
2147 // Feature gate SIMD types in FFI, since I am not sure that the
2148 // ABIs are handled at all correctly. -huonw
2149 if abi != abi::Abi::RustIntrinsic
2150 && abi != abi::Abi::PlatformIntrinsic
2151 && !tcx.features().simd_ffi
2153 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2158 .span_to_snippet(ast_ty.span)
2159 .map_or(String::new(), |s| format!(" `{}`", s));
2164 "use of SIMD type{} in FFI is highly experimental and \
2165 may result in invalid code",
2169 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2173 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2176 if let hir::FnRetTy::Return(ref ty) = decl.output {
2177 check(&ty, *fty.output().skip_binder())
2184 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2185 match tcx.hir().get_if_local(def_id) {
2186 Some(Node::ForeignItem(..)) => true,
2188 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2192 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2193 match tcx.hir().get_if_local(def_id) {
2195 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2196 | Node::ForeignItem(&hir::ForeignItem {
2197 kind: hir::ForeignItemKind::Static(_, mutbl),
2202 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2206 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2207 match tcx.hir().get_if_local(def_id) {
2208 Some(Node::Expr(&rustc_hir::Expr {
2209 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2211 })) => tcx.hir().body(body_id).generator_kind(),
2213 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2217 fn from_target_feature(
2220 attr: &ast::Attribute,
2221 whitelist: &FxHashMap<String, Option<Symbol>>,
2222 target_features: &mut Vec<Symbol>,
2224 let list = match attr.meta_item_list() {
2228 let bad_item = |span| {
2229 let msg = "malformed `target_feature` attribute input";
2230 let code = "enable = \"..\"".to_owned();
2232 .struct_span_err(span, &msg)
2233 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2236 let rust_features = tcx.features();
2238 // Only `enable = ...` is accepted in the meta-item list.
2239 if !item.check_name(sym::enable) {
2240 bad_item(item.span());
2244 // Must be of the form `enable = "..."` (a string).
2245 let value = match item.value_str() {
2246 Some(value) => value,
2248 bad_item(item.span());
2253 // We allow comma separation to enable multiple features.
2254 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2255 // Only allow whitelisted features per platform.
2256 let feature_gate = match whitelist.get(feature) {
2260 format!("the feature named `{}` is not valid for this target", feature);
2261 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2264 format!("`{}` is not valid for this target", feature),
2266 if feature.starts_with('+') {
2267 let valid = whitelist.contains_key(&feature[1..]);
2269 err.help("consider removing the leading `+` in the feature name");
2277 // Only allow features whose feature gates have been enabled.
2278 let allowed = match feature_gate.as_ref().copied() {
2279 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2280 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2281 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2282 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2283 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2284 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2285 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2286 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2287 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2288 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2289 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2290 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2291 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2292 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2293 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2294 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2295 Some(name) => bug!("unknown target feature gate {}", name),
2298 if !allowed && id.is_local() {
2300 &tcx.sess.parse_sess,
2301 feature_gate.unwrap(),
2303 &format!("the target feature `{}` is currently unstable", feature),
2307 Some(Symbol::intern(feature))
2312 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2313 use rustc_middle::mir::mono::Linkage::*;
2315 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2316 // applicable to variable declarations and may not really make sense for
2317 // Rust code in the first place but whitelist them anyway and trust that
2318 // the user knows what s/he's doing. Who knows, unanticipated use cases
2319 // may pop up in the future.
2321 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2322 // and don't have to be, LLVM treats them as no-ops.
2324 "appending" => Appending,
2325 "available_externally" => AvailableExternally,
2327 "extern_weak" => ExternalWeak,
2328 "external" => External,
2329 "internal" => Internal,
2330 "linkonce" => LinkOnceAny,
2331 "linkonce_odr" => LinkOnceODR,
2332 "private" => Private,
2334 "weak_odr" => WeakODR,
2336 let span = tcx.hir().span_if_local(def_id);
2337 if let Some(span) = span {
2338 tcx.sess.span_fatal(span, "invalid linkage specified")
2340 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2346 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2347 let attrs = tcx.get_attrs(id);
2349 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2350 if should_inherit_track_caller(tcx, id) {
2351 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2354 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2356 let mut inline_span = None;
2357 let mut link_ordinal_span = None;
2358 let mut no_sanitize_span = None;
2359 for attr in attrs.iter() {
2360 if attr.check_name(sym::cold) {
2361 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2362 } else if attr.check_name(sym::rustc_allocator) {
2363 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2364 } else if attr.check_name(sym::unwind) {
2365 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2366 } else if attr.check_name(sym::ffi_returns_twice) {
2367 if tcx.is_foreign_item(id) {
2368 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2370 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2375 "`#[ffi_returns_twice]` may only be used on foreign functions"
2379 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2380 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2381 } else if attr.check_name(sym::naked) {
2382 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2383 } else if attr.check_name(sym::no_mangle) {
2384 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2385 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2386 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2387 } else if attr.check_name(sym::used) {
2388 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2389 } else if attr.check_name(sym::thread_local) {
2390 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2391 } else if attr.check_name(sym::track_caller) {
2392 if tcx.is_closure(id) || tcx.fn_sig(id).abi() != abi::Abi::Rust {
2393 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2396 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2397 } else if attr.check_name(sym::export_name) {
2398 if let Some(s) = attr.value_str() {
2399 if s.as_str().contains('\0') {
2400 // `#[export_name = ...]` will be converted to a null-terminated string,
2401 // so it may not contain any null characters.
2406 "`export_name` may not contain null characters"
2410 codegen_fn_attrs.export_name = Some(s);
2412 } else if attr.check_name(sym::target_feature) {
2413 if !tcx.features().target_feature_11 {
2414 check_target_feature_safe_fn(tcx, id, attr.span);
2415 } else if let Some(local_id) = id.as_local() {
2416 if tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2417 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2420 from_target_feature(tcx, id, attr, &whitelist, &mut codegen_fn_attrs.target_features);
2421 } else if attr.check_name(sym::linkage) {
2422 if let Some(val) = attr.value_str() {
2423 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2425 } else if attr.check_name(sym::link_section) {
2426 if let Some(val) = attr.value_str() {
2427 if val.as_str().bytes().any(|b| b == 0) {
2429 "illegal null byte in link_section \
2433 tcx.sess.span_err(attr.span, &msg);
2435 codegen_fn_attrs.link_section = Some(val);
2438 } else if attr.check_name(sym::link_name) {
2439 codegen_fn_attrs.link_name = attr.value_str();
2440 } else if attr.check_name(sym::link_ordinal) {
2441 link_ordinal_span = Some(attr.span);
2442 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2443 codegen_fn_attrs.link_ordinal = ordinal;
2445 } else if attr.check_name(sym::no_sanitize) {
2446 no_sanitize_span = Some(attr.span);
2447 if let Some(list) = attr.meta_item_list() {
2448 for item in list.iter() {
2449 if item.check_name(sym::address) {
2450 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_SANITIZE_ADDRESS;
2451 } else if item.check_name(sym::memory) {
2452 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_SANITIZE_MEMORY;
2453 } else if item.check_name(sym::thread) {
2454 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_SANITIZE_THREAD;
2457 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2458 .note("expected one of: `address`, `memory` or `thread`")
2466 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2467 if !attr.has_name(sym::inline) {
2470 match attr.meta().map(|i| i.kind) {
2471 Some(MetaItemKind::Word) => {
2475 Some(MetaItemKind::List(ref items)) => {
2477 inline_span = Some(attr.span);
2478 if items.len() != 1 {
2480 tcx.sess.diagnostic(),
2483 "expected one argument"
2487 } else if list_contains_name(&items[..], sym::always) {
2489 } else if list_contains_name(&items[..], sym::never) {
2493 tcx.sess.diagnostic(),
2503 Some(MetaItemKind::NameValue(_)) => ia,
2508 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2509 if !attr.has_name(sym::optimize) {
2512 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
2513 match attr.meta().map(|i| i.kind) {
2514 Some(MetaItemKind::Word) => {
2515 err(attr.span, "expected one argument");
2518 Some(MetaItemKind::List(ref items)) => {
2520 inline_span = Some(attr.span);
2521 if items.len() != 1 {
2522 err(attr.span, "expected one argument");
2524 } else if list_contains_name(&items[..], sym::size) {
2526 } else if list_contains_name(&items[..], sym::speed) {
2529 err(items[0].span(), "invalid argument");
2533 Some(MetaItemKind::NameValue(_)) => ia,
2538 // If a function uses #[target_feature] it can't be inlined into general
2539 // purpose functions as they wouldn't have the right target features
2540 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2542 if !codegen_fn_attrs.target_features.is_empty() {
2543 if codegen_fn_attrs.inline == InlineAttr::Always {
2544 if let Some(span) = inline_span {
2547 "cannot use `#[inline(always)]` with \
2548 `#[target_feature]`",
2554 if codegen_fn_attrs.flags.intersects(CodegenFnAttrFlags::NO_SANITIZE_ANY) {
2555 if codegen_fn_attrs.inline == InlineAttr::Always {
2556 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
2557 let hir_id = tcx.hir().as_local_hir_id(id.expect_local());
2558 tcx.struct_span_lint_hir(
2559 lint::builtin::INLINE_NO_SANITIZE,
2563 lint.build("`no_sanitize` will have no effect after inlining")
2564 .span_note(inline_span, "inlining requested here")
2572 // Weak lang items have the same semantics as "std internal" symbols in the
2573 // sense that they're preserved through all our LTO passes and only
2574 // strippable by the linker.
2576 // Additionally weak lang items have predetermined symbol names.
2577 if tcx.is_weak_lang_item(id) {
2578 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2580 if let Some(name) = weak_lang_items::link_name(&attrs) {
2581 codegen_fn_attrs.export_name = Some(name);
2582 codegen_fn_attrs.link_name = Some(name);
2584 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2586 // Internal symbols to the standard library all have no_mangle semantics in
2587 // that they have defined symbol names present in the function name. This
2588 // also applies to weak symbols where they all have known symbol names.
2589 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2590 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2596 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
2597 /// applied to the method prototype.
2598 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2599 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
2600 if let ty::AssocItemContainer::ImplContainer(impl_def_id) = impl_item.container {
2601 if let Some(trait_def_id) = tcx.trait_id_of_impl(impl_def_id) {
2602 if let Some(trait_item) = tcx
2603 .associated_items(trait_def_id)
2604 .filter_by_name_unhygienic(impl_item.ident.name)
2605 .find(move |trait_item| {
2606 trait_item.kind == ty::AssocKind::Fn
2607 && tcx.hygienic_eq(impl_item.ident, trait_item.ident, trait_def_id)
2611 .codegen_fn_attrs(trait_item.def_id)
2613 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
2622 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
2623 use rustc_ast::ast::{Lit, LitIntType, LitKind};
2624 let meta_item_list = attr.meta_item_list();
2625 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
2626 let sole_meta_list = match meta_item_list {
2627 Some([item]) => item.literal(),
2630 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
2631 if *ordinal <= usize::MAX as u128 {
2632 Some(*ordinal as usize)
2634 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
2636 .struct_span_err(attr.span, &msg)
2637 .note("the value may not exceed `usize::MAX`")
2643 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
2644 .note("an unsuffixed integer value, e.g., `1`, is expected")
2650 fn check_link_name_xor_ordinal(
2652 codegen_fn_attrs: &CodegenFnAttrs,
2653 inline_span: Option<Span>,
2655 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
2658 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
2659 if let Some(span) = inline_span {
2660 tcx.sess.span_err(span, msg);
2666 /// Checks the function annotated with `#[target_feature]` is unsafe,
2667 /// reporting an error if it isn't.
2668 fn check_target_feature_safe_fn(tcx: TyCtxt<'_>, id: DefId, attr_span: Span) {
2669 if tcx.is_closure(id) || tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2670 let mut err = feature_err(
2671 &tcx.sess.parse_sess,
2672 sym::target_feature_11,
2674 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2676 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2681 /// Checks the function annotated with `#[target_feature]` is not a safe
2682 /// trait method implementation, reporting an error if it is.
2683 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
2684 let hir_id = tcx.hir().as_local_hir_id(id);
2685 let node = tcx.hir().get(hir_id);
2686 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
2687 let parent_id = tcx.hir().get_parent_item(hir_id);
2688 let parent_item = tcx.hir().expect_item(parent_id);
2689 if let hir::ItemKind::Impl { of_trait: Some(_), .. } = parent_item.kind {
2693 "`#[target_feature(..)]` cannot be applied to safe trait method",
2695 .span_label(attr_span, "cannot be applied to safe trait method")
2696 .span_label(tcx.def_span(id), "not an `unsafe` function")