1 // ignore-tidy-filelength
2 //! "Collection" is the process of determining the type and other external
3 //! details of each item in Rust. Collection is specifically concerned
4 //! with *inter-procedural* things -- for example, for a function
5 //! definition, collection will figure out the type and signature of the
6 //! function, but it will not visit the *body* of the function in any way,
7 //! nor examine type annotations on local variables (that's the job of
10 //! Collecting is ultimately defined by a bundle of queries that
11 //! inquire after various facts about the items in the crate (e.g.,
12 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
15 //! At present, however, we do run collection across all items in the
16 //! crate as a kind of pass. This should eventually be factored away.
18 use crate::astconv::{AstConv, SizedByDefault};
19 use crate::bounds::Bounds;
20 use crate::check::intrinsic::intrinsic_operation_unsafety;
21 use crate::constrained_generic_params as cgp;
23 use crate::middle::resolve_lifetime as rl;
25 use rustc_ast::{MetaItemKind, NestedMetaItem};
26 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
27 use rustc_data_structures::captures::Captures;
28 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
29 use rustc_errors::{struct_span_err, Applicability};
31 use rustc_hir::def::{CtorKind, DefKind, Res};
32 use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
33 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
34 use rustc_hir::weak_lang_items;
35 use rustc_hir::{GenericParamKind, HirId, Node};
36 use rustc_middle::hir::map::blocks::FnLikeNode;
37 use rustc_middle::hir::map::Map;
38 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
39 use rustc_middle::mir::mono::Linkage;
40 use rustc_middle::ty::query::Providers;
41 use rustc_middle::ty::subst::InternalSubsts;
42 use rustc_middle::ty::util::Discr;
43 use rustc_middle::ty::util::IntTypeExt;
44 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, ToPolyTraitRef, Ty, TyCtxt};
45 use rustc_middle::ty::{ReprOptions, ToPredicate, WithConstness};
46 use rustc_session::config::SanitizerSet;
47 use rustc_session::lint;
48 use rustc_session::parse::feature_err;
49 use rustc_span::symbol::{kw, sym, Ident, Symbol};
50 use rustc_span::{Span, DUMMY_SP};
51 use rustc_target::spec::abi;
52 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
57 struct OnlySelfBounds(bool);
59 ///////////////////////////////////////////////////////////////////////////
62 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
63 tcx.hir().visit_item_likes_in_module(
65 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
69 pub fn provide(providers: &mut Providers) {
70 *providers = Providers {
71 opt_const_param_of: type_of::opt_const_param_of,
72 type_of: type_of::type_of,
73 item_bounds: item_bounds::item_bounds,
74 explicit_item_bounds: item_bounds::explicit_item_bounds,
77 predicates_defined_on,
78 projection_ty_from_predicates,
79 explicit_predicates_of,
81 super_predicates_that_define_assoc_type,
82 trait_explicit_predicates_and_bounds,
83 type_param_predicates,
93 collect_mod_item_types,
98 ///////////////////////////////////////////////////////////////////////////
100 /// Context specific to some particular item. This is what implements
101 /// `AstConv`. It has information about the predicates that are defined
102 /// on the trait. Unfortunately, this predicate information is
103 /// available in various different forms at various points in the
104 /// process. So we can't just store a pointer to e.g., the AST or the
105 /// parsed ty form, we have to be more flexible. To this end, the
106 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
107 /// `get_type_parameter_bounds` requests, drawing the information from
108 /// the AST (`hir::Generics`), recursively.
109 pub struct ItemCtxt<'tcx> {
114 ///////////////////////////////////////////////////////////////////////////
117 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
119 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
120 type Map = intravisit::ErasedMap<'v>;
122 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
123 NestedVisitorMap::None
125 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
126 if let hir::TyKind::Infer = t.kind {
129 intravisit::walk_ty(self, t)
133 struct CollectItemTypesVisitor<'tcx> {
137 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
138 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
139 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
140 crate fn placeholder_type_error(
143 generics: &[hir::GenericParam<'_>],
144 placeholder_types: Vec<Span>,
146 hir_ty: Option<&hir::Ty<'_>>,
148 if placeholder_types.is_empty() {
152 let type_name = generics.next_type_param_name(None);
153 let mut sugg: Vec<_> =
154 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
156 if generics.is_empty() {
157 if let Some(span) = span {
158 sugg.push((span, format!("<{}>", type_name)));
160 } else if let Some(arg) = generics
162 .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
164 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
165 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
166 sugg.push((arg.span, (*type_name).to_string()));
168 let last = generics.iter().last().unwrap();
170 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
171 last.bounds_span().unwrap_or(last.span).shrink_to_hi(),
172 format!(", {}", type_name),
176 let mut err = bad_placeholder_type(tcx, placeholder_types);
178 // Suggest, but only if it is not a function in const or static
180 let mut is_fn = false;
181 let mut is_const = false;
182 let mut is_static = false;
184 if let Some(hir_ty) = hir_ty {
185 if let hir::TyKind::BareFn(_) = hir_ty.kind {
188 // Check if parent is const or static
189 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
190 let parent_node = tcx.hir().get(parent_id);
192 if let hir::Node::Item(item) = parent_node {
193 if let hir::ItemKind::Const(_, _) = item.kind {
195 } else if let hir::ItemKind::Static(_, _, _) = item.kind {
202 // if function is wrapped around a const or static,
203 // then don't show the suggestion
204 if !(is_fn && (is_const || is_static)) {
205 err.multipart_suggestion(
206 "use type parameters instead",
208 Applicability::HasPlaceholders,
215 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
216 let (generics, suggest) = match &item.kind {
217 hir::ItemKind::Union(_, generics)
218 | hir::ItemKind::Enum(_, generics)
219 | hir::ItemKind::TraitAlias(generics, _)
220 | hir::ItemKind::Trait(_, _, generics, ..)
221 | hir::ItemKind::Impl(hir::Impl { generics, .. })
222 | hir::ItemKind::Struct(_, generics) => (generics, true),
223 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
224 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
225 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
229 let mut visitor = PlaceholderHirTyCollector::default();
230 visitor.visit_item(item);
232 placeholder_type_error(tcx, Some(generics.span), generics.params, visitor.0, suggest, None);
235 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
236 type Map = Map<'tcx>;
238 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
239 NestedVisitorMap::OnlyBodies(self.tcx.hir())
242 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
243 convert_item(self.tcx, item.item_id());
244 reject_placeholder_type_signatures_in_item(self.tcx, item);
245 intravisit::walk_item(self, item);
248 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
249 for param in generics.params {
251 hir::GenericParamKind::Lifetime { .. } => {}
252 hir::GenericParamKind::Type { default: Some(_), .. } => {
253 let def_id = self.tcx.hir().local_def_id(param.hir_id);
254 self.tcx.ensure().type_of(def_id);
256 hir::GenericParamKind::Type { .. } => {}
257 hir::GenericParamKind::Const { .. } => {
258 let def_id = self.tcx.hir().local_def_id(param.hir_id);
259 self.tcx.ensure().type_of(def_id);
260 // FIXME(const_generics_defaults)
264 intravisit::walk_generics(self, generics);
267 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
268 if let hir::ExprKind::Closure(..) = expr.kind {
269 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
270 self.tcx.ensure().generics_of(def_id);
271 self.tcx.ensure().type_of(def_id);
273 intravisit::walk_expr(self, expr);
276 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
277 convert_trait_item(self.tcx, trait_item.trait_item_id());
278 intravisit::walk_trait_item(self, trait_item);
281 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
282 convert_impl_item(self.tcx, impl_item.impl_item_id());
283 intravisit::walk_impl_item(self, impl_item);
287 ///////////////////////////////////////////////////////////////////////////
288 // Utility types and common code for the above passes.
290 fn bad_placeholder_type(
292 mut spans: Vec<Span>,
293 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
295 let mut err = struct_span_err!(
299 "the type placeholder `_` is not allowed within types on item signatures",
302 err.span_label(span, "not allowed in type signatures");
307 impl ItemCtxt<'tcx> {
308 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
309 ItemCtxt { tcx, item_def_id }
312 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
313 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
316 pub fn hir_id(&self) -> hir::HirId {
317 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
320 pub fn node(&self) -> hir::Node<'tcx> {
321 self.tcx.hir().get(self.hir_id())
325 impl AstConv<'tcx> for ItemCtxt<'tcx> {
326 fn tcx(&self) -> TyCtxt<'tcx> {
330 fn item_def_id(&self) -> Option<DefId> {
331 Some(self.item_def_id)
334 fn default_constness_for_trait_bounds(&self) -> hir::Constness {
335 if let Some(fn_like) = FnLikeNode::from_node(self.node()) {
338 hir::Constness::NotConst
342 fn get_type_parameter_bounds(
347 ) -> ty::GenericPredicates<'tcx> {
348 self.tcx.at(span).type_param_predicates((
350 def_id.expect_local(),
355 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
359 fn allow_ty_infer(&self) -> bool {
363 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
364 self.tcx().ty_error_with_message(span, "bad_placeholder_type")
370 _: Option<&ty::GenericParamDef>,
372 ) -> &'tcx Const<'tcx> {
373 bad_placeholder_type(self.tcx(), vec![span]).emit();
374 // Typeck doesn't expect erased regions to be returned from `type_of`.
375 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match r {
376 ty::ReErased => self.tcx.lifetimes.re_static,
379 self.tcx().const_error(ty)
382 fn projected_ty_from_poly_trait_ref(
386 item_segment: &hir::PathSegment<'_>,
387 poly_trait_ref: ty::PolyTraitRef<'tcx>,
389 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
390 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
398 self.tcx().mk_projection(item_def_id, item_substs)
400 // There are no late-bound regions; we can just ignore the binder.
401 let mut err = struct_span_err!(
405 "cannot use the associated type of a trait \
406 with uninferred generic parameters"
410 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
412 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
414 hir::ItemKind::Enum(_, generics)
415 | hir::ItemKind::Struct(_, generics)
416 | hir::ItemKind::Union(_, generics) => {
417 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
418 let (lt_sp, sugg) = match generics.params {
419 [] => (generics.span, format!("<{}>", lt_name)),
421 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
424 let suggestions = vec![
430 // Replace the existing lifetimes with a new named lifetime.
432 .replace_late_bound_regions(poly_trait_ref, |_| {
433 self.tcx.mk_region(ty::ReEarlyBound(
434 ty::EarlyBoundRegion {
437 name: Symbol::intern(<_name),
446 err.multipart_suggestion(
447 "use a fully qualified path with explicit lifetimes",
449 Applicability::MaybeIncorrect,
455 hir::Node::Item(hir::Item {
457 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
461 | hir::Node::ForeignItem(_)
462 | hir::Node::TraitItem(_)
463 | hir::Node::ImplItem(_) => {
466 "use a fully qualified path with inferred lifetimes",
469 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
470 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
473 Applicability::MaybeIncorrect,
479 self.tcx().ty_error()
483 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
484 // Types in item signatures are not normalized to avoid undue dependencies.
488 fn set_tainted_by_errors(&self) {
489 // There's no obvious place to track this, so just let it go.
492 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
493 // There's no place to record types from signatures?
497 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
498 fn get_new_lifetime_name<'tcx>(
500 poly_trait_ref: ty::PolyTraitRef<'tcx>,
501 generics: &hir::Generics<'tcx>,
503 let existing_lifetimes = tcx
504 .collect_referenced_late_bound_regions(&poly_trait_ref)
507 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
508 Some(name.as_str().to_string())
513 .chain(generics.params.iter().filter_map(|param| {
514 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
515 Some(param.name.ident().as_str().to_string())
520 .collect::<FxHashSet<String>>();
522 let a_to_z_repeat_n = |n| {
523 (b'a'..=b'z').map(move |c| {
524 let mut s = '\''.to_string();
525 s.extend(std::iter::repeat(char::from(c)).take(n));
530 // If all single char lifetime names are present, we wrap around and double the chars.
531 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
534 /// Returns the predicates defined on `item_def_id` of the form
535 /// `X: Foo` where `X` is the type parameter `def_id`.
536 fn type_param_predicates(
538 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
539 ) -> ty::GenericPredicates<'_> {
542 // In the AST, bounds can derive from two places. Either
543 // written inline like `<T: Foo>` or in a where-clause like
546 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
547 let param_owner = tcx.hir().ty_param_owner(param_id);
548 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
549 let generics = tcx.generics_of(param_owner_def_id);
550 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
551 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
553 // Don't look for bounds where the type parameter isn't in scope.
554 let parent = if item_def_id == param_owner_def_id.to_def_id() {
557 tcx.generics_of(item_def_id).parent
560 let mut result = parent
562 let icx = ItemCtxt::new(tcx, parent);
563 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
565 .unwrap_or_default();
566 let mut extend = None;
568 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
569 let ast_generics = match tcx.hir().get(item_hir_id) {
570 Node::TraitItem(item) => &item.generics,
572 Node::ImplItem(item) => &item.generics,
574 Node::Item(item) => {
576 ItemKind::Fn(.., ref generics, _)
577 | ItemKind::Impl(hir::Impl { ref generics, .. })
578 | ItemKind::TyAlias(_, ref generics)
579 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
580 | ItemKind::Enum(_, ref generics)
581 | ItemKind::Struct(_, ref generics)
582 | ItemKind::Union(_, ref generics) => generics,
583 ItemKind::Trait(_, _, ref generics, ..) => {
584 // Implied `Self: Trait` and supertrait bounds.
585 if param_id == item_hir_id {
586 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
588 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
596 Node::ForeignItem(item) => match item.kind {
597 ForeignItemKind::Fn(_, _, ref generics) => generics,
604 let icx = ItemCtxt::new(tcx, item_def_id);
605 let extra_predicates = extend.into_iter().chain(
606 icx.type_parameter_bounds_in_generics(
610 OnlySelfBounds(true),
614 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
615 ty::PredicateKind::Trait(data, _) => data.self_ty().is_param(index),
620 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
624 impl ItemCtxt<'tcx> {
625 /// Finds bounds from `hir::Generics`. This requires scanning through the
626 /// AST. We do this to avoid having to convert *all* the bounds, which
627 /// would create artificial cycles. Instead, we can only convert the
628 /// bounds for a type parameter `X` if `X::Foo` is used.
629 fn type_parameter_bounds_in_generics(
631 ast_generics: &'tcx hir::Generics<'tcx>,
632 param_id: hir::HirId,
634 only_self_bounds: OnlySelfBounds,
635 assoc_name: Option<Ident>,
636 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
637 let constness = self.default_constness_for_trait_bounds();
638 let from_ty_params = ast_generics
641 .filter_map(|param| match param.kind {
642 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
645 .flat_map(|bounds| bounds.iter())
646 .filter(|b| match assoc_name {
647 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
650 .flat_map(|b| predicates_from_bound(self, ty, b, constness));
652 let from_where_clauses = ast_generics
656 .filter_map(|wp| match *wp {
657 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
661 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
663 } else if !only_self_bounds.0 {
664 Some(self.to_ty(&bp.bounded_ty))
670 .filter(|b| match assoc_name {
671 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
674 .filter_map(move |b| bt.map(|bt| (bt, b)))
676 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b, constness));
678 from_ty_params.chain(from_where_clauses).collect()
681 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
682 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
685 hir::GenericBound::Trait(poly_trait_ref, _) => {
686 let trait_ref = &poly_trait_ref.trait_ref;
687 if let Some(trait_did) = trait_ref.trait_def_id() {
688 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
698 /// Tests whether this is the AST for a reference to the type
699 /// parameter with ID `param_id`. We use this so as to avoid running
700 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
701 /// conversion of the type to avoid inducing unnecessary cycles.
702 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
703 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
705 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
706 def_id == tcx.hir().local_def_id(param_id).to_def_id()
715 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
716 let it = tcx.hir().item(item_id);
717 debug!("convert: item {} with id {}", it.ident, it.hir_id());
718 let def_id = item_id.def_id;
721 // These don't define types.
722 hir::ItemKind::ExternCrate(_)
723 | hir::ItemKind::Use(..)
724 | hir::ItemKind::Mod(_)
725 | hir::ItemKind::GlobalAsm(_) => {}
726 hir::ItemKind::ForeignMod { items, .. } => {
728 let item = tcx.hir().foreign_item(item.id);
729 tcx.ensure().generics_of(item.def_id);
730 tcx.ensure().type_of(item.def_id);
731 tcx.ensure().predicates_of(item.def_id);
732 if let hir::ForeignItemKind::Fn(..) = item.kind {
733 tcx.ensure().fn_sig(item.def_id);
737 hir::ItemKind::Enum(ref enum_definition, _) => {
738 tcx.ensure().generics_of(def_id);
739 tcx.ensure().type_of(def_id);
740 tcx.ensure().predicates_of(def_id);
741 convert_enum_variant_types(tcx, def_id.to_def_id(), &enum_definition.variants);
743 hir::ItemKind::Impl { .. } => {
744 tcx.ensure().generics_of(def_id);
745 tcx.ensure().type_of(def_id);
746 tcx.ensure().impl_trait_ref(def_id);
747 tcx.ensure().predicates_of(def_id);
749 hir::ItemKind::Trait(..) => {
750 tcx.ensure().generics_of(def_id);
751 tcx.ensure().trait_def(def_id);
752 tcx.at(it.span).super_predicates_of(def_id);
753 tcx.ensure().predicates_of(def_id);
755 hir::ItemKind::TraitAlias(..) => {
756 tcx.ensure().generics_of(def_id);
757 tcx.at(it.span).super_predicates_of(def_id);
758 tcx.ensure().predicates_of(def_id);
760 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
761 tcx.ensure().generics_of(def_id);
762 tcx.ensure().type_of(def_id);
763 tcx.ensure().predicates_of(def_id);
765 for f in struct_def.fields() {
766 let def_id = tcx.hir().local_def_id(f.hir_id);
767 tcx.ensure().generics_of(def_id);
768 tcx.ensure().type_of(def_id);
769 tcx.ensure().predicates_of(def_id);
772 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
773 convert_variant_ctor(tcx, ctor_hir_id);
777 // Desugared from `impl Trait`, so visited by the function's return type.
778 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
780 // Don't call `type_of` on opaque types, since that depends on type
781 // checking function bodies. `check_item_type` ensures that it's called
783 hir::ItemKind::OpaqueTy(..) => {
784 tcx.ensure().generics_of(def_id);
785 tcx.ensure().predicates_of(def_id);
786 tcx.ensure().explicit_item_bounds(def_id);
788 hir::ItemKind::TyAlias(..)
789 | hir::ItemKind::Static(..)
790 | hir::ItemKind::Const(..)
791 | hir::ItemKind::Fn(..) => {
792 tcx.ensure().generics_of(def_id);
793 tcx.ensure().type_of(def_id);
794 tcx.ensure().predicates_of(def_id);
796 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
797 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
804 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
805 let trait_item = tcx.hir().trait_item(trait_item_id);
806 tcx.ensure().generics_of(trait_item_id.def_id);
808 match trait_item.kind {
809 hir::TraitItemKind::Fn(..) => {
810 tcx.ensure().type_of(trait_item_id.def_id);
811 tcx.ensure().fn_sig(trait_item_id.def_id);
814 hir::TraitItemKind::Const(.., Some(_)) => {
815 tcx.ensure().type_of(trait_item_id.def_id);
818 hir::TraitItemKind::Const(..) => {
819 tcx.ensure().type_of(trait_item_id.def_id);
820 // Account for `const C: _;`.
821 let mut visitor = PlaceholderHirTyCollector::default();
822 visitor.visit_trait_item(trait_item);
823 placeholder_type_error(tcx, None, &[], visitor.0, false, None);
826 hir::TraitItemKind::Type(_, Some(_)) => {
827 tcx.ensure().item_bounds(trait_item_id.def_id);
828 tcx.ensure().type_of(trait_item_id.def_id);
829 // Account for `type T = _;`.
830 let mut visitor = PlaceholderHirTyCollector::default();
831 visitor.visit_trait_item(trait_item);
832 placeholder_type_error(tcx, None, &[], visitor.0, false, None);
835 hir::TraitItemKind::Type(_, None) => {
836 tcx.ensure().item_bounds(trait_item_id.def_id);
837 // #74612: Visit and try to find bad placeholders
838 // even if there is no concrete type.
839 let mut visitor = PlaceholderHirTyCollector::default();
840 visitor.visit_trait_item(trait_item);
842 placeholder_type_error(tcx, None, &[], visitor.0, false, None);
846 tcx.ensure().predicates_of(trait_item_id.def_id);
849 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
850 let def_id = impl_item_id.def_id;
851 tcx.ensure().generics_of(def_id);
852 tcx.ensure().type_of(def_id);
853 tcx.ensure().predicates_of(def_id);
854 let impl_item = tcx.hir().impl_item(impl_item_id);
855 match impl_item.kind {
856 hir::ImplItemKind::Fn(..) => {
857 tcx.ensure().fn_sig(def_id);
859 hir::ImplItemKind::TyAlias(_) => {
860 // Account for `type T = _;`
861 let mut visitor = PlaceholderHirTyCollector::default();
862 visitor.visit_impl_item(impl_item);
864 placeholder_type_error(tcx, None, &[], visitor.0, false, None);
866 hir::ImplItemKind::Const(..) => {}
870 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
871 let def_id = tcx.hir().local_def_id(ctor_id);
872 tcx.ensure().generics_of(def_id);
873 tcx.ensure().type_of(def_id);
874 tcx.ensure().predicates_of(def_id);
877 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
878 let def = tcx.adt_def(def_id);
879 let repr_type = def.repr.discr_type();
880 let initial = repr_type.initial_discriminant(tcx);
881 let mut prev_discr = None::<Discr<'_>>;
883 // fill the discriminant values and field types
884 for variant in variants {
885 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
887 if let Some(ref e) = variant.disr_expr {
888 let expr_did = tcx.hir().local_def_id(e.hir_id);
889 def.eval_explicit_discr(tcx, expr_did.to_def_id())
890 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
893 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
896 format!("overflowed on value after {}", prev_discr.unwrap()),
899 "explicitly set `{} = {}` if that is desired outcome",
900 variant.ident, wrapped_discr
905 .unwrap_or(wrapped_discr),
908 for f in variant.data.fields() {
909 let def_id = tcx.hir().local_def_id(f.hir_id);
910 tcx.ensure().generics_of(def_id);
911 tcx.ensure().type_of(def_id);
912 tcx.ensure().predicates_of(def_id);
915 // Convert the ctor, if any. This also registers the variant as
917 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
918 convert_variant_ctor(tcx, ctor_hir_id);
925 variant_did: Option<LocalDefId>,
926 ctor_did: Option<LocalDefId>,
928 discr: ty::VariantDiscr,
929 def: &hir::VariantData<'_>,
930 adt_kind: ty::AdtKind,
931 parent_did: LocalDefId,
932 ) -> ty::VariantDef {
933 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
938 let fid = tcx.hir().local_def_id(f.hir_id);
939 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
940 if let Some(prev_span) = dup_span {
941 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
947 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
950 ty::FieldDef { did: fid.to_def_id(), ident: f.ident, vis: tcx.visibility(fid) }
953 let recovered = match def {
954 hir::VariantData::Struct(_, r) => *r,
959 variant_did.map(LocalDefId::to_def_id),
960 ctor_did.map(LocalDefId::to_def_id),
963 CtorKind::from_hir(def),
965 parent_did.to_def_id(),
967 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
968 || variant_did.map_or(false, |variant_did| {
969 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
974 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
977 let def_id = def_id.expect_local();
978 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
979 let item = match tcx.hir().get(hir_id) {
980 Node::Item(item) => item,
984 let repr = ReprOptions::new(tcx, def_id.to_def_id());
985 let (kind, variants) = match item.kind {
986 ItemKind::Enum(ref def, _) => {
987 let mut distance_from_explicit = 0;
992 let variant_did = Some(tcx.hir().local_def_id(v.id));
994 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
996 let discr = if let Some(ref e) = v.disr_expr {
997 distance_from_explicit = 0;
998 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1000 ty::VariantDiscr::Relative(distance_from_explicit)
1002 distance_from_explicit += 1;
1017 (AdtKind::Enum, variants)
1019 ItemKind::Struct(ref def, _) => {
1020 let variant_did = None::<LocalDefId>;
1021 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1023 let variants = std::iter::once(convert_variant(
1028 ty::VariantDiscr::Relative(0),
1035 (AdtKind::Struct, variants)
1037 ItemKind::Union(ref def, _) => {
1038 let variant_did = None;
1039 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1041 let variants = std::iter::once(convert_variant(
1046 ty::VariantDiscr::Relative(0),
1053 (AdtKind::Union, variants)
1057 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1060 /// Ensures that the super-predicates of the trait with a `DefId`
1061 /// of `trait_def_id` are converted and stored. This also ensures that
1062 /// the transitive super-predicates are converted.
1063 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1064 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1065 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1068 /// Ensures that the super-predicates of the trait with a `DefId`
1069 /// of `trait_def_id` are converted and stored. This also ensures that
1070 /// the transitive super-predicates are converted.
1071 fn super_predicates_that_define_assoc_type(
1073 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1074 ) -> ty::GenericPredicates<'_> {
1076 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1077 trait_def_id, assoc_name
1079 if trait_def_id.is_local() {
1080 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1081 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1083 let item = match tcx.hir().get(trait_hir_id) {
1084 Node::Item(item) => item,
1085 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
1088 let (generics, bounds) = match item.kind {
1089 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1090 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1091 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1094 let icx = ItemCtxt::new(tcx, trait_def_id);
1096 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1097 let self_param_ty = tcx.types.self_param;
1098 let superbounds1 = if let Some(assoc_name) = assoc_name {
1099 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1108 <dyn AstConv<'_>>::compute_bounds(
1117 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1119 // Convert any explicit superbounds in the where-clause,
1120 // e.g., `trait Foo where Self: Bar`.
1121 // In the case of trait aliases, however, we include all bounds in the where-clause,
1122 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1123 // as one of its "superpredicates".
1124 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1125 let superbounds2 = icx.type_parameter_bounds_in_generics(
1129 OnlySelfBounds(!is_trait_alias),
1133 // Combine the two lists to form the complete set of superbounds:
1134 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1136 // Now require that immediate supertraits are converted,
1137 // which will, in turn, reach indirect supertraits.
1138 if assoc_name.is_none() {
1139 // Now require that immediate supertraits are converted,
1140 // which will, in turn, reach indirect supertraits.
1141 for &(pred, span) in superbounds {
1142 debug!("superbound: {:?}", pred);
1143 if let ty::PredicateKind::Trait(bound, _) = pred.kind().skip_binder() {
1144 tcx.at(span).super_predicates_of(bound.def_id());
1149 ty::GenericPredicates { parent: None, predicates: superbounds }
1151 // if `assoc_name` is None, then the query should've been redirected to an
1152 // external provider
1153 assert!(assoc_name.is_some());
1154 tcx.super_predicates_of(trait_def_id)
1158 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1159 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1160 let item = tcx.hir().expect_item(hir_id);
1162 let (is_auto, unsafety) = match item.kind {
1163 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
1164 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
1165 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1168 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1169 if paren_sugar && !tcx.features().unboxed_closures {
1173 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1174 which traits can use parenthetical notation",
1176 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1180 let is_marker = tcx.has_attr(def_id, sym::marker);
1181 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1182 ty::trait_def::TraitSpecializationKind::Marker
1183 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1184 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1186 ty::trait_def::TraitSpecializationKind::None
1188 let def_path_hash = tcx.def_path_hash(def_id);
1189 ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, spec_kind, def_path_hash)
1192 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1193 struct LateBoundRegionsDetector<'tcx> {
1195 outer_index: ty::DebruijnIndex,
1196 has_late_bound_regions: Option<Span>,
1199 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1200 type Map = intravisit::ErasedMap<'tcx>;
1202 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1203 NestedVisitorMap::None
1206 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1207 if self.has_late_bound_regions.is_some() {
1211 hir::TyKind::BareFn(..) => {
1212 self.outer_index.shift_in(1);
1213 intravisit::walk_ty(self, ty);
1214 self.outer_index.shift_out(1);
1216 _ => intravisit::walk_ty(self, ty),
1220 fn visit_poly_trait_ref(
1222 tr: &'tcx hir::PolyTraitRef<'tcx>,
1223 m: hir::TraitBoundModifier,
1225 if self.has_late_bound_regions.is_some() {
1228 self.outer_index.shift_in(1);
1229 intravisit::walk_poly_trait_ref(self, tr, m);
1230 self.outer_index.shift_out(1);
1233 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1234 if self.has_late_bound_regions.is_some() {
1238 match self.tcx.named_region(lt.hir_id) {
1239 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1241 rl::Region::LateBound(debruijn, _, _) | rl::Region::LateBoundAnon(debruijn, _),
1242 ) if debruijn < self.outer_index => {}
1244 rl::Region::LateBound(..)
1245 | rl::Region::LateBoundAnon(..)
1246 | rl::Region::Free(..),
1249 self.has_late_bound_regions = Some(lt.span);
1255 fn has_late_bound_regions<'tcx>(
1257 generics: &'tcx hir::Generics<'tcx>,
1258 decl: &'tcx hir::FnDecl<'tcx>,
1260 let mut visitor = LateBoundRegionsDetector {
1262 outer_index: ty::INNERMOST,
1263 has_late_bound_regions: None,
1265 for param in generics.params {
1266 if let GenericParamKind::Lifetime { .. } = param.kind {
1267 if tcx.is_late_bound(param.hir_id) {
1268 return Some(param.span);
1272 visitor.visit_fn_decl(decl);
1273 visitor.has_late_bound_regions
1277 Node::TraitItem(item) => match item.kind {
1278 hir::TraitItemKind::Fn(ref sig, _) => {
1279 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1283 Node::ImplItem(item) => match item.kind {
1284 hir::ImplItemKind::Fn(ref sig, _) => {
1285 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1289 Node::ForeignItem(item) => match item.kind {
1290 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
1291 has_late_bound_regions(tcx, generics, fn_decl)
1295 Node::Item(item) => match item.kind {
1296 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1297 has_late_bound_regions(tcx, generics, &sig.decl)
1305 struct AnonConstInParamListDetector {
1306 in_param_list: bool,
1307 found_anon_const_in_list: bool,
1311 impl<'v> Visitor<'v> for AnonConstInParamListDetector {
1312 type Map = intravisit::ErasedMap<'v>;
1314 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1315 NestedVisitorMap::None
1318 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1319 let prev = self.in_param_list;
1320 self.in_param_list = true;
1321 intravisit::walk_generic_param(self, p);
1322 self.in_param_list = prev;
1325 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1326 if self.in_param_list && self.ct == c.hir_id {
1327 self.found_anon_const_in_list = true;
1329 intravisit::walk_anon_const(self, c)
1334 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1337 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1339 let node = tcx.hir().get(hir_id);
1340 let parent_def_id = match node {
1342 | Node::TraitItem(_)
1345 | Node::Field(_) => {
1346 let parent_id = tcx.hir().get_parent_item(hir_id);
1347 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1349 // FIXME(#43408) always enable this once `lazy_normalization` is
1350 // stable enough and does not need a feature gate anymore.
1351 Node::AnonConst(_) => {
1352 let parent_id = tcx.hir().get_parent_item(hir_id);
1353 let parent_def_id = tcx.hir().local_def_id(parent_id);
1355 let mut in_param_list = false;
1356 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1357 if let Some(generics) = node.generics() {
1358 let mut visitor = AnonConstInParamListDetector {
1359 in_param_list: false,
1360 found_anon_const_in_list: false,
1364 visitor.visit_generics(generics);
1365 in_param_list = visitor.found_anon_const_in_list;
1371 // We do not allow generic parameters in anon consts if we are inside
1374 // This affects both default type bindings, e.g. `struct<T, U = [u8; std::mem::size_of::<T>()]>(T, U)`,
1375 // and the types of const parameters, e.g. `struct V<const N: usize, const M: [u8; N]>();`.
1377 } else if tcx.lazy_normalization() {
1378 // HACK(eddyb) this provides the correct generics when
1379 // `feature(const_generics)` is enabled, so that const expressions
1380 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1382 // Note that we do not supply the parent generics when using
1383 // `min_const_generics`.
1384 Some(parent_def_id.to_def_id())
1386 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1388 // HACK(eddyb) this provides the correct generics for repeat
1389 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1390 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1391 // as they shouldn't be able to cause query cycle errors.
1392 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1393 | Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1394 if constant.hir_id == hir_id =>
1396 Some(parent_def_id.to_def_id())
1403 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1404 Some(tcx.closure_base_def_id(def_id))
1406 Node::Item(item) => match item.kind {
1407 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => {
1408 impl_trait_fn.or_else(|| {
1409 let parent_id = tcx.hir().get_parent_item(hir_id);
1410 assert!(parent_id != hir_id && parent_id != CRATE_HIR_ID);
1411 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1412 // Opaque types are always nested within another item, and
1413 // inherit the generics of the item.
1414 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1422 let mut opt_self = None;
1423 let mut allow_defaults = false;
1425 let no_generics = hir::Generics::empty();
1426 let ast_generics = match node {
1427 Node::TraitItem(item) => &item.generics,
1429 Node::ImplItem(item) => &item.generics,
1431 Node::Item(item) => {
1433 ItemKind::Fn(.., ref generics, _)
1434 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1436 ItemKind::TyAlias(_, ref generics)
1437 | ItemKind::Enum(_, ref generics)
1438 | ItemKind::Struct(_, ref generics)
1439 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1440 | ItemKind::Union(_, ref generics) => {
1441 allow_defaults = true;
1445 ItemKind::Trait(_, _, ref generics, ..)
1446 | ItemKind::TraitAlias(ref generics, ..) => {
1447 // Add in the self type parameter.
1449 // Something of a hack: use the node id for the trait, also as
1450 // the node id for the Self type parameter.
1451 let param_id = item.def_id;
1453 opt_self = Some(ty::GenericParamDef {
1455 name: kw::SelfUpper,
1456 def_id: param_id.to_def_id(),
1457 pure_wrt_drop: false,
1458 kind: ty::GenericParamDefKind::Type {
1460 object_lifetime_default: rl::Set1::Empty,
1465 allow_defaults = true;
1473 Node::ForeignItem(item) => match item.kind {
1474 ForeignItemKind::Static(..) => &no_generics,
1475 ForeignItemKind::Fn(_, _, ref generics) => generics,
1476 ForeignItemKind::Type => &no_generics,
1482 let has_self = opt_self.is_some();
1483 let mut parent_has_self = false;
1484 let mut own_start = has_self as u32;
1485 let parent_count = parent_def_id.map_or(0, |def_id| {
1486 let generics = tcx.generics_of(def_id);
1487 assert_eq!(has_self, false);
1488 parent_has_self = generics.has_self;
1489 own_start = generics.count() as u32;
1490 generics.parent_count + generics.params.len()
1493 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1495 if let Some(opt_self) = opt_self {
1496 params.push(opt_self);
1499 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1500 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1501 name: param.name.ident().name,
1502 index: own_start + i as u32,
1503 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1504 pure_wrt_drop: param.pure_wrt_drop,
1505 kind: ty::GenericParamDefKind::Lifetime,
1508 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1510 // Now create the real type and const parameters.
1511 let type_start = own_start - has_self as u32 + params.len() as u32;
1514 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1515 GenericParamKind::Lifetime { .. } => None,
1516 GenericParamKind::Type { ref default, synthetic, .. } => {
1517 if !allow_defaults && default.is_some() {
1518 if !tcx.features().default_type_parameter_fallback {
1519 tcx.struct_span_lint_hir(
1520 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1525 "defaults for type parameters are only allowed in \
1526 `struct`, `enum`, `type`, or `trait` definitions.",
1534 let kind = ty::GenericParamDefKind::Type {
1535 has_default: default.is_some(),
1536 object_lifetime_default: object_lifetime_defaults
1538 .map_or(rl::Set1::Empty, |o| o[i]),
1542 let param_def = ty::GenericParamDef {
1543 index: type_start + i as u32,
1544 name: param.name.ident().name,
1545 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1546 pure_wrt_drop: param.pure_wrt_drop,
1552 GenericParamKind::Const { .. } => {
1553 let param_def = ty::GenericParamDef {
1554 index: type_start + i as u32,
1555 name: param.name.ident().name,
1556 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1557 pure_wrt_drop: param.pure_wrt_drop,
1558 kind: ty::GenericParamDefKind::Const,
1565 // provide junk type parameter defs - the only place that
1566 // cares about anything but the length is instantiation,
1567 // and we don't do that for closures.
1568 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1569 let dummy_args = if gen.is_some() {
1570 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1572 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1575 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1576 index: type_start + i as u32,
1577 name: Symbol::intern(arg),
1579 pure_wrt_drop: false,
1580 kind: ty::GenericParamDefKind::Type {
1582 object_lifetime_default: rl::Set1::Empty,
1588 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1591 parent: parent_def_id,
1594 param_def_id_to_index,
1595 has_self: has_self || parent_has_self,
1596 has_late_bound_regions: has_late_bound_regions(tcx, node),
1600 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1603 .filter_map(|arg| match arg {
1604 hir::GenericArg::Type(ty) => Some(ty),
1607 .any(is_suggestable_infer_ty)
1610 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1611 /// use inference to provide suggestions for the appropriate type if possible.
1612 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1616 Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
1617 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1618 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1619 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1620 Path(hir::QPath::TypeRelative(ty, segment)) => {
1621 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1623 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1624 ty_opt.map_or(false, is_suggestable_infer_ty)
1625 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1631 pub fn get_infer_ret_ty(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1632 if let hir::FnRetTy::Return(ref ty) = output {
1633 if is_suggestable_infer_ty(ty) {
1640 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1641 use rustc_hir::Node::*;
1644 let def_id = def_id.expect_local();
1645 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1647 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1649 match tcx.hir().get(hir_id) {
1650 TraitItem(hir::TraitItem {
1651 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1656 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1657 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1658 match get_infer_ret_ty(&sig.decl.output) {
1660 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1661 // Typeck doesn't expect erased regions to be returned from `type_of`.
1662 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match r {
1663 ty::ReErased => tcx.lifetimes.re_static,
1667 let mut visitor = PlaceholderHirTyCollector::default();
1668 visitor.visit_ty(ty);
1669 let mut diag = bad_placeholder_type(tcx, visitor.0);
1670 let ret_ty = fn_sig.output();
1671 if ret_ty != tcx.ty_error() {
1672 if !ret_ty.is_closure() {
1673 let ret_ty_str = match ret_ty.kind() {
1674 // Suggest a function pointer return type instead of a unique function definition
1675 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1677 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1678 _ => ret_ty.to_string(),
1680 diag.span_suggestion(
1682 "replace with the correct return type",
1684 Applicability::MaybeIncorrect,
1687 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1688 // to prevent the user from getting a papercut while trying to use the unique closure
1689 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1690 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1691 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1696 ty::Binder::bind(fn_sig)
1698 None => <dyn AstConv<'_>>::ty_of_fn(
1700 sig.header.unsafety,
1710 TraitItem(hir::TraitItem {
1711 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1715 }) => <dyn AstConv<'_>>::ty_of_fn(
1725 ForeignItem(&hir::ForeignItem {
1726 kind: ForeignItemKind::Fn(ref fn_decl, _, _),
1730 let abi = tcx.hir().get_foreign_abi(hir_id);
1731 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1734 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1735 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id).to_def_id());
1737 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1738 ty::Binder::bind(tcx.mk_fn_sig(
1742 hir::Unsafety::Normal,
1747 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1748 // Closure signatures are not like other function
1749 // signatures and cannot be accessed through `fn_sig`. For
1750 // example, a closure signature excludes the `self`
1751 // argument. In any case they are embedded within the
1752 // closure type as part of the `ClosureSubsts`.
1754 // To get the signature of a closure, you should use the
1755 // `sig` method on the `ClosureSubsts`:
1757 // substs.as_closure().sig(def_id, tcx)
1759 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1764 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1769 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1770 let icx = ItemCtxt::new(tcx, def_id);
1772 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1773 match tcx.hir().expect_item(hir_id).kind {
1774 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1775 let selfty = tcx.type_of(def_id);
1776 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1782 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1783 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1784 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1785 let item = tcx.hir().expect_item(hir_id);
1787 hir::ItemKind::Impl(hir::Impl {
1788 polarity: hir::ImplPolarity::Negative(span),
1792 if is_rustc_reservation {
1793 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
1794 tcx.sess.span_err(span, "reservation impls can't be negative");
1796 ty::ImplPolarity::Negative
1798 hir::ItemKind::Impl(hir::Impl {
1799 polarity: hir::ImplPolarity::Positive,
1803 if is_rustc_reservation {
1804 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1806 ty::ImplPolarity::Positive
1808 hir::ItemKind::Impl(hir::Impl {
1809 polarity: hir::ImplPolarity::Positive,
1813 if is_rustc_reservation {
1814 ty::ImplPolarity::Reservation
1816 ty::ImplPolarity::Positive
1819 item => bug!("impl_polarity: {:?} not an impl", item),
1823 /// Returns the early-bound lifetimes declared in this generics
1824 /// listing. For anything other than fns/methods, this is just all
1825 /// the lifetimes that are declared. For fns or methods, we have to
1826 /// screen out those that do not appear in any where-clauses etc using
1827 /// `resolve_lifetime::early_bound_lifetimes`.
1828 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1830 generics: &'a hir::Generics<'a>,
1831 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1832 generics.params.iter().filter(move |param| match param.kind {
1833 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1838 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1839 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1840 /// inferred constraints concerning which regions outlive other regions.
1841 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1842 debug!("predicates_defined_on({:?})", def_id);
1843 let mut result = tcx.explicit_predicates_of(def_id);
1844 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1845 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1846 if !inferred_outlives.is_empty() {
1848 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1849 def_id, inferred_outlives,
1851 if result.predicates.is_empty() {
1852 result.predicates = inferred_outlives;
1854 result.predicates = tcx
1856 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1860 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1864 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1865 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1866 /// `Self: Trait` predicates for traits.
1867 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1868 let mut result = tcx.predicates_defined_on(def_id);
1870 if tcx.is_trait(def_id) {
1871 // For traits, add `Self: Trait` predicate. This is
1872 // not part of the predicates that a user writes, but it
1873 // is something that one must prove in order to invoke a
1874 // method or project an associated type.
1876 // In the chalk setup, this predicate is not part of the
1877 // "predicates" for a trait item. But it is useful in
1878 // rustc because if you directly (e.g.) invoke a trait
1879 // method like `Trait::method(...)`, you must naturally
1880 // prove that the trait applies to the types that were
1881 // used, and adding the predicate into this list ensures
1882 // that this is done.
1883 let span = tcx.sess.source_map().guess_head_span(tcx.def_span(def_id));
1885 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
1886 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
1890 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1894 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1895 /// N.B., this does not include any implied/inferred constraints.
1896 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1899 debug!("explicit_predicates_of(def_id={:?})", def_id);
1901 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1902 let node = tcx.hir().get(hir_id);
1904 let mut is_trait = None;
1905 let mut is_default_impl_trait = None;
1907 let icx = ItemCtxt::new(tcx, def_id);
1908 let constness = icx.default_constness_for_trait_bounds();
1910 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
1912 // We use an `IndexSet` to preserves order of insertion.
1913 // Preserving the order of insertion is important here so as not to break UI tests.
1914 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
1916 let ast_generics = match node {
1917 Node::TraitItem(item) => &item.generics,
1919 Node::ImplItem(item) => &item.generics,
1921 Node::Item(item) => {
1923 ItemKind::Impl(ref impl_) => {
1924 if impl_.defaultness.is_default() {
1925 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1929 ItemKind::Fn(.., ref generics, _)
1930 | ItemKind::TyAlias(_, ref generics)
1931 | ItemKind::Enum(_, ref generics)
1932 | ItemKind::Struct(_, ref generics)
1933 | ItemKind::Union(_, ref generics) => generics,
1935 ItemKind::Trait(_, _, ref generics, ..) => {
1936 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
1939 ItemKind::TraitAlias(ref generics, _) => {
1940 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
1943 ItemKind::OpaqueTy(OpaqueTy {
1949 if impl_trait_fn.is_some() {
1950 // return-position impl trait
1952 // We don't inherit predicates from the parent here:
1953 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
1954 // then the return type is `f::<'static, T>::{{opaque}}`.
1956 // If we inherited the predicates of `f` then we would
1957 // require that `T: 'static` to show that the return
1958 // type is well-formed.
1960 // The only way to have something with this opaque type
1961 // is from the return type of the containing function,
1962 // which will ensure that the function's predicates
1964 return ty::GenericPredicates { parent: None, predicates: &[] };
1966 // type-alias impl trait
1975 Node::ForeignItem(item) => match item.kind {
1976 ForeignItemKind::Static(..) => NO_GENERICS,
1977 ForeignItemKind::Fn(_, _, ref generics) => generics,
1978 ForeignItemKind::Type => NO_GENERICS,
1984 let generics = tcx.generics_of(def_id);
1985 let parent_count = generics.parent_count as u32;
1986 let has_own_self = generics.has_self && parent_count == 0;
1988 // Below we'll consider the bounds on the type parameters (including `Self`)
1989 // and the explicit where-clauses, but to get the full set of predicates
1990 // on a trait we need to add in the supertrait bounds and bounds found on
1991 // associated types.
1992 if let Some(_trait_ref) = is_trait {
1993 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
1996 // In default impls, we can assume that the self type implements
1997 // the trait. So in:
1999 // default impl Foo for Bar { .. }
2001 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2002 // (see below). Recall that a default impl is not itself an impl, but rather a
2003 // set of defaults that can be incorporated into another impl.
2004 if let Some(trait_ref) = is_default_impl_trait {
2006 trait_ref.to_poly_trait_ref().without_const().to_predicate(tcx),
2007 tcx.def_span(def_id),
2011 // Collect the region predicates that were declared inline as
2012 // well. In the case of parameters declared on a fn or method, we
2013 // have to be careful to only iterate over early-bound regions.
2014 let mut index = parent_count + has_own_self as u32;
2015 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2016 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2017 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2019 name: param.name.ident().name,
2024 GenericParamKind::Lifetime { .. } => {
2025 param.bounds.iter().for_each(|bound| match bound {
2026 hir::GenericBound::Outlives(lt) => {
2027 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, <, None);
2028 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2029 predicates.insert((outlives.to_predicate(tcx), lt.span));
2038 // Collect the predicates that were written inline by the user on each
2039 // type parameter (e.g., `<T: Foo>`).
2040 for param in ast_generics.params {
2042 // We already dealt with early bound lifetimes above.
2043 GenericParamKind::Lifetime { .. } => (),
2044 GenericParamKind::Type { .. } => {
2045 let name = param.name.ident().name;
2046 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2049 let sized = SizedByDefault::Yes;
2050 let bounds = <dyn AstConv<'_>>::compute_bounds(
2057 predicates.extend(bounds.predicates(tcx, param_ty));
2059 GenericParamKind::Const { .. } => {
2060 // Bounds on const parameters are currently not possible.
2061 debug_assert!(param.bounds.is_empty());
2067 // Add in the bounds that appear in the where-clause.
2068 let where_clause = &ast_generics.where_clause;
2069 for predicate in where_clause.predicates {
2071 hir::WherePredicate::BoundPredicate(bound_pred) => {
2072 let ty = icx.to_ty(&bound_pred.bounded_ty);
2074 // Keep the type around in a dummy predicate, in case of no bounds.
2075 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2076 // is still checked for WF.
2077 if bound_pred.bounds.is_empty() {
2078 if let ty::Param(_) = ty.kind() {
2079 // This is a `where T:`, which can be in the HIR from the
2080 // transformation that moves `?Sized` to `T`'s declaration.
2081 // We can skip the predicate because type parameters are
2082 // trivially WF, but also we *should*, to avoid exposing
2083 // users who never wrote `where Type:,` themselves, to
2084 // compiler/tooling bugs from not handling WF predicates.
2086 let span = bound_pred.bounded_ty.span;
2087 let re_root_empty = tcx.lifetimes.re_root_empty;
2088 let predicate = ty::Binder::bind(ty::PredicateKind::TypeOutlives(
2089 ty::OutlivesPredicate(ty, re_root_empty),
2091 predicates.insert((predicate.to_predicate(tcx), span));
2095 for bound in bound_pred.bounds.iter() {
2097 hir::GenericBound::Trait(poly_trait_ref, modifier) => {
2098 let constness = match modifier {
2099 hir::TraitBoundModifier::MaybeConst => hir::Constness::NotConst,
2100 hir::TraitBoundModifier::None => constness,
2101 hir::TraitBoundModifier::Maybe => bug!("this wasn't handled"),
2104 let mut bounds = Bounds::default();
2105 let _ = <dyn AstConv<'_>>::instantiate_poly_trait_ref(
2112 predicates.extend(bounds.predicates(tcx, ty));
2115 &hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => {
2116 let mut bounds = Bounds::default();
2117 <dyn AstConv<'_>>::instantiate_lang_item_trait_ref(
2126 predicates.extend(bounds.predicates(tcx, ty));
2129 hir::GenericBound::Outlives(lifetime) => {
2131 <dyn AstConv<'_>>::ast_region_to_region(&icx, lifetime, None);
2133 ty::Binder::bind(ty::PredicateKind::TypeOutlives(
2134 ty::OutlivesPredicate(ty, region),
2144 hir::WherePredicate::RegionPredicate(region_pred) => {
2145 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2146 predicates.extend(region_pred.bounds.iter().map(|bound| {
2147 let (r2, span) = match bound {
2148 hir::GenericBound::Outlives(lt) => {
2149 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2153 let pred = ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(r1, r2))
2154 .to_predicate(icx.tcx);
2160 hir::WherePredicate::EqPredicate(..) => {
2166 if tcx.features().const_evaluatable_checked {
2167 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2170 let mut predicates: Vec<_> = predicates.into_iter().collect();
2172 // Subtle: before we store the predicates into the tcx, we
2173 // sort them so that predicates like `T: Foo<Item=U>` come
2174 // before uses of `U`. This avoids false ambiguity errors
2175 // in trait checking. See `setup_constraining_predicates`
2177 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2178 let self_ty = tcx.type_of(def_id);
2179 let trait_ref = tcx.impl_trait_ref(def_id);
2180 cgp::setup_constraining_predicates(
2184 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2188 let result = ty::GenericPredicates {
2189 parent: generics.parent,
2190 predicates: tcx.arena.alloc_from_iter(predicates),
2192 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2196 fn const_evaluatable_predicates_of<'tcx>(
2199 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2200 struct ConstCollector<'tcx> {
2202 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2205 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2206 type Map = Map<'tcx>;
2208 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
2209 intravisit::NestedVisitorMap::None
2212 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2213 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2214 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2215 if let ty::ConstKind::Unevaluated(uv) = ct.val {
2216 assert_eq!(uv.promoted, None);
2217 let span = self.tcx.hir().span(c.hir_id);
2219 ty::PredicateKind::ConstEvaluatable(uv.def, uv.substs).to_predicate(self.tcx),
2226 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2227 let node = tcx.hir().get(hir_id);
2229 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2230 if let hir::Node::Item(item) = node {
2231 if let hir::ItemKind::Impl(ref impl_) = item.kind {
2232 if let Some(of_trait) = &impl_.of_trait {
2233 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2234 collector.visit_trait_ref(of_trait);
2237 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2238 collector.visit_ty(impl_.self_ty);
2242 if let Some(generics) = node.generics() {
2243 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2244 collector.visit_generics(generics);
2247 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2248 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2249 collector.visit_fn_decl(fn_sig.decl);
2251 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2256 fn trait_explicit_predicates_and_bounds(
2259 ) -> ty::GenericPredicates<'_> {
2260 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2261 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2264 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2265 if let DefKind::Trait = tcx.def_kind(def_id) {
2266 // Remove bounds on associated types from the predicates, they will be
2267 // returned by `explicit_item_bounds`.
2268 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2269 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2271 let is_assoc_item_ty = |ty: Ty<'_>| {
2272 // For a predicate from a where clause to become a bound on an
2274 // * It must use the identity substs of the item.
2275 // * Since any generic parameters on the item are not in scope,
2276 // this means that the item is not a GAT, and its identity
2277 // substs are the same as the trait's.
2278 // * It must be an associated type for this trait (*not* a
2280 if let ty::Projection(projection) = ty.kind() {
2281 projection.substs == trait_identity_substs
2282 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2288 let predicates: Vec<_> = predicates_and_bounds
2292 .filter(|(pred, _)| match pred.kind().skip_binder() {
2293 ty::PredicateKind::Trait(tr, _) => !is_assoc_item_ty(tr.self_ty()),
2294 ty::PredicateKind::Projection(proj) => {
2295 !is_assoc_item_ty(proj.projection_ty.self_ty())
2297 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2301 if predicates.len() == predicates_and_bounds.predicates.len() {
2302 predicates_and_bounds
2304 ty::GenericPredicates {
2305 parent: predicates_and_bounds.parent,
2306 predicates: tcx.arena.alloc_slice(&predicates),
2310 gather_explicit_predicates_of(tcx, def_id)
2314 fn projection_ty_from_predicates(
2319 // def_id of `N` in `<T as Trait>::N`
2322 ) -> Option<ty::ProjectionTy<'tcx>> {
2323 let (ty_def_id, item_def_id) = key;
2324 let mut projection_ty = None;
2325 for (predicate, _) in tcx.predicates_of(ty_def_id).predicates {
2326 if let ty::PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder()
2328 if item_def_id == projection_predicate.projection_ty.item_def_id {
2329 projection_ty = Some(projection_predicate.projection_ty);
2337 /// Converts a specific `GenericBound` from the AST into a set of
2338 /// predicates that apply to the self type. A vector is returned
2339 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2340 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2341 /// and `<T as Bar>::X == i32`).
2342 fn predicates_from_bound<'tcx>(
2343 astconv: &dyn AstConv<'tcx>,
2345 bound: &'tcx hir::GenericBound<'tcx>,
2346 constness: hir::Constness,
2347 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2349 hir::GenericBound::Trait(ref tr, modifier) => {
2350 let constness = match modifier {
2351 hir::TraitBoundModifier::Maybe => return vec![],
2352 hir::TraitBoundModifier::MaybeConst => hir::Constness::NotConst,
2353 hir::TraitBoundModifier::None => constness,
2356 let mut bounds = Bounds::default();
2357 let _ = astconv.instantiate_poly_trait_ref(tr, constness, param_ty, &mut bounds);
2358 bounds.predicates(astconv.tcx(), param_ty)
2360 hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => {
2361 let mut bounds = Bounds::default();
2362 astconv.instantiate_lang_item_trait_ref(
2370 bounds.predicates(astconv.tcx(), param_ty)
2372 hir::GenericBound::Outlives(ref lifetime) => {
2373 let region = astconv.ast_region_to_region(lifetime, None);
2374 let pred = ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(param_ty, region))
2375 .to_predicate(astconv.tcx());
2376 vec![(pred, lifetime.span)]
2381 fn compute_sig_of_foreign_fn_decl<'tcx>(
2384 decl: &'tcx hir::FnDecl<'tcx>,
2387 ) -> ty::PolyFnSig<'tcx> {
2388 let unsafety = if abi == abi::Abi::RustIntrinsic {
2389 intrinsic_operation_unsafety(tcx.item_name(def_id))
2391 hir::Unsafety::Unsafe
2393 let fty = <dyn AstConv<'_>>::ty_of_fn(
2394 &ItemCtxt::new(tcx, def_id),
2398 &hir::Generics::empty(),
2403 // Feature gate SIMD types in FFI, since I am not sure that the
2404 // ABIs are handled at all correctly. -huonw
2405 if abi != abi::Abi::RustIntrinsic
2406 && abi != abi::Abi::PlatformIntrinsic
2407 && !tcx.features().simd_ffi
2409 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2414 .span_to_snippet(ast_ty.span)
2415 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2420 "use of SIMD type{} in FFI is highly experimental and \
2421 may result in invalid code",
2425 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2429 for (input, ty) in decl.inputs.iter().zip(fty.inputs().skip_binder()) {
2432 if let hir::FnRetTy::Return(ref ty) = decl.output {
2433 check(&ty, fty.output().skip_binder())
2440 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2441 match tcx.hir().get_if_local(def_id) {
2442 Some(Node::ForeignItem(..)) => true,
2444 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2448 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2449 match tcx.hir().get_if_local(def_id) {
2451 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2452 | Node::ForeignItem(&hir::ForeignItem {
2453 kind: hir::ForeignItemKind::Static(_, mutbl),
2458 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2462 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2463 match tcx.hir().get_if_local(def_id) {
2464 Some(Node::Expr(&rustc_hir::Expr {
2465 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2467 })) => tcx.hir().body(body_id).generator_kind(),
2469 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2473 fn from_target_feature(
2476 attr: &ast::Attribute,
2477 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2478 target_features: &mut Vec<Symbol>,
2480 let list = match attr.meta_item_list() {
2484 let bad_item = |span| {
2485 let msg = "malformed `target_feature` attribute input";
2486 let code = "enable = \"..\"".to_owned();
2488 .struct_span_err(span, &msg)
2489 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2492 let rust_features = tcx.features();
2494 // Only `enable = ...` is accepted in the meta-item list.
2495 if !item.has_name(sym::enable) {
2496 bad_item(item.span());
2500 // Must be of the form `enable = "..."` (a string).
2501 let value = match item.value_str() {
2502 Some(value) => value,
2504 bad_item(item.span());
2509 // We allow comma separation to enable multiple features.
2510 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2511 let feature_gate = match supported_target_features.get(feature) {
2515 format!("the feature named `{}` is not valid for this target", feature);
2516 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2519 format!("`{}` is not valid for this target", feature),
2521 if let Some(stripped) = feature.strip_prefix('+') {
2522 let valid = supported_target_features.contains_key(stripped);
2524 err.help("consider removing the leading `+` in the feature name");
2532 // Only allow features whose feature gates have been enabled.
2533 let allowed = match feature_gate.as_ref().copied() {
2534 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2535 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2536 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2537 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2538 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2539 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2540 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2541 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2542 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2543 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2544 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2545 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2546 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2547 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2548 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2549 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2550 Some(name) => bug!("unknown target feature gate {}", name),
2553 if !allowed && id.is_local() {
2555 &tcx.sess.parse_sess,
2556 feature_gate.unwrap(),
2558 &format!("the target feature `{}` is currently unstable", feature),
2562 Some(Symbol::intern(feature))
2567 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2568 use rustc_middle::mir::mono::Linkage::*;
2570 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2571 // applicable to variable declarations and may not really make sense for
2572 // Rust code in the first place but allow them anyway and trust that the
2573 // user knows what s/he's doing. Who knows, unanticipated use cases may pop
2574 // up in the future.
2576 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2577 // and don't have to be, LLVM treats them as no-ops.
2579 "appending" => Appending,
2580 "available_externally" => AvailableExternally,
2582 "extern_weak" => ExternalWeak,
2583 "external" => External,
2584 "internal" => Internal,
2585 "linkonce" => LinkOnceAny,
2586 "linkonce_odr" => LinkOnceODR,
2587 "private" => Private,
2589 "weak_odr" => WeakODR,
2591 let span = tcx.hir().span_if_local(def_id);
2592 if let Some(span) = span {
2593 tcx.sess.span_fatal(span, "invalid linkage specified")
2595 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2601 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2602 let attrs = tcx.get_attrs(id);
2604 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2605 if should_inherit_track_caller(tcx, id) {
2606 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2609 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2611 let mut inline_span = None;
2612 let mut link_ordinal_span = None;
2613 let mut no_sanitize_span = None;
2614 for attr in attrs.iter() {
2615 if tcx.sess.check_name(attr, sym::cold) {
2616 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2617 } else if tcx.sess.check_name(attr, sym::rustc_allocator) {
2618 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2619 } else if tcx.sess.check_name(attr, sym::unwind) {
2620 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2621 } else if tcx.sess.check_name(attr, sym::ffi_returns_twice) {
2622 if tcx.is_foreign_item(id) {
2623 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2625 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2630 "`#[ffi_returns_twice]` may only be used on foreign functions"
2634 } else if tcx.sess.check_name(attr, sym::ffi_pure) {
2635 if tcx.is_foreign_item(id) {
2636 if attrs.iter().any(|a| tcx.sess.check_name(a, sym::ffi_const)) {
2637 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2642 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2646 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2649 // `#[ffi_pure]` is only allowed on foreign functions
2654 "`#[ffi_pure]` may only be used on foreign functions"
2658 } else if tcx.sess.check_name(attr, sym::ffi_const) {
2659 if tcx.is_foreign_item(id) {
2660 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2662 // `#[ffi_const]` is only allowed on foreign functions
2667 "`#[ffi_const]` may only be used on foreign functions"
2671 } else if tcx.sess.check_name(attr, sym::rustc_allocator_nounwind) {
2672 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2673 } else if tcx.sess.check_name(attr, sym::naked) {
2674 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2675 } else if tcx.sess.check_name(attr, sym::no_mangle) {
2676 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2677 } else if tcx.sess.check_name(attr, sym::rustc_std_internal_symbol) {
2678 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2679 } else if tcx.sess.check_name(attr, sym::used) {
2680 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2681 } else if tcx.sess.check_name(attr, sym::cmse_nonsecure_entry) {
2682 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2687 "`#[cmse_nonsecure_entry]` requires C ABI"
2691 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2692 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2695 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2696 } else if tcx.sess.check_name(attr, sym::thread_local) {
2697 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2698 } else if tcx.sess.check_name(attr, sym::track_caller) {
2699 if tcx.is_closure(id) || tcx.fn_sig(id).abi() != abi::Abi::Rust {
2700 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2703 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2704 } else if tcx.sess.check_name(attr, sym::export_name) {
2705 if let Some(s) = attr.value_str() {
2706 if s.as_str().contains('\0') {
2707 // `#[export_name = ...]` will be converted to a null-terminated string,
2708 // so it may not contain any null characters.
2713 "`export_name` may not contain null characters"
2717 codegen_fn_attrs.export_name = Some(s);
2719 } else if tcx.sess.check_name(attr, sym::target_feature) {
2720 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2721 if !tcx.features().target_feature_11 {
2722 let mut err = feature_err(
2723 &tcx.sess.parse_sess,
2724 sym::target_feature_11,
2726 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2728 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2730 } else if let Some(local_id) = id.as_local() {
2731 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2734 from_target_feature(
2738 &supported_target_features,
2739 &mut codegen_fn_attrs.target_features,
2741 } else if tcx.sess.check_name(attr, sym::linkage) {
2742 if let Some(val) = attr.value_str() {
2743 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2745 } else if tcx.sess.check_name(attr, sym::link_section) {
2746 if let Some(val) = attr.value_str() {
2747 if val.as_str().bytes().any(|b| b == 0) {
2749 "illegal null byte in link_section \
2753 tcx.sess.span_err(attr.span, &msg);
2755 codegen_fn_attrs.link_section = Some(val);
2758 } else if tcx.sess.check_name(attr, sym::link_name) {
2759 codegen_fn_attrs.link_name = attr.value_str();
2760 } else if tcx.sess.check_name(attr, sym::link_ordinal) {
2761 link_ordinal_span = Some(attr.span);
2762 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2763 codegen_fn_attrs.link_ordinal = ordinal;
2765 } else if tcx.sess.check_name(attr, sym::no_sanitize) {
2766 no_sanitize_span = Some(attr.span);
2767 if let Some(list) = attr.meta_item_list() {
2768 for item in list.iter() {
2769 if item.has_name(sym::address) {
2770 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2771 } else if item.has_name(sym::memory) {
2772 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2773 } else if item.has_name(sym::thread) {
2774 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2775 } else if item.has_name(sym::hwaddress) {
2776 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2779 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2780 .note("expected one of: `address`, `hwaddress`, `memory` or `thread`")
2785 } else if tcx.sess.check_name(attr, sym::instruction_set) {
2786 codegen_fn_attrs.instruction_set = match attr.meta().map(|i| i.kind) {
2787 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
2788 [NestedMetaItem::MetaItem(set)] => {
2790 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
2791 match segments.as_slice() {
2792 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
2793 if !tcx.sess.target.has_thumb_interworking {
2795 tcx.sess.diagnostic(),
2798 "target does not support `#[instruction_set]`"
2802 } else if segments[1] == sym::a32 {
2803 Some(InstructionSetAttr::ArmA32)
2804 } else if segments[1] == sym::t32 {
2805 Some(InstructionSetAttr::ArmT32)
2812 tcx.sess.diagnostic(),
2815 "invalid instruction set specified",
2824 tcx.sess.diagnostic(),
2827 "`#[instruction_set]` requires an argument"
2834 tcx.sess.diagnostic(),
2837 "cannot specify more than one instruction set"
2845 tcx.sess.diagnostic(),
2848 "must specify an instruction set"
2857 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2858 if !attr.has_name(sym::inline) {
2861 match attr.meta().map(|i| i.kind) {
2862 Some(MetaItemKind::Word) => {
2863 tcx.sess.mark_attr_used(attr);
2866 Some(MetaItemKind::List(ref items)) => {
2867 tcx.sess.mark_attr_used(attr);
2868 inline_span = Some(attr.span);
2869 if items.len() != 1 {
2871 tcx.sess.diagnostic(),
2874 "expected one argument"
2878 } else if list_contains_name(&items[..], sym::always) {
2880 } else if list_contains_name(&items[..], sym::never) {
2884 tcx.sess.diagnostic(),
2894 Some(MetaItemKind::NameValue(_)) => ia,
2899 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2900 if !attr.has_name(sym::optimize) {
2903 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
2904 match attr.meta().map(|i| i.kind) {
2905 Some(MetaItemKind::Word) => {
2906 err(attr.span, "expected one argument");
2909 Some(MetaItemKind::List(ref items)) => {
2910 tcx.sess.mark_attr_used(attr);
2911 inline_span = Some(attr.span);
2912 if items.len() != 1 {
2913 err(attr.span, "expected one argument");
2915 } else if list_contains_name(&items[..], sym::size) {
2917 } else if list_contains_name(&items[..], sym::speed) {
2920 err(items[0].span(), "invalid argument");
2924 Some(MetaItemKind::NameValue(_)) => ia,
2929 // #73631: closures inherit `#[target_feature]` annotations
2930 if tcx.features().target_feature_11 && tcx.is_closure(id) {
2931 let owner_id = tcx.parent(id).expect("closure should have a parent");
2934 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
2937 // If a function uses #[target_feature] it can't be inlined into general
2938 // purpose functions as they wouldn't have the right target features
2939 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2941 if !codegen_fn_attrs.target_features.is_empty() {
2942 if codegen_fn_attrs.inline == InlineAttr::Always {
2943 if let Some(span) = inline_span {
2946 "cannot use `#[inline(always)]` with \
2947 `#[target_feature]`",
2953 if !codegen_fn_attrs.no_sanitize.is_empty() {
2954 if codegen_fn_attrs.inline == InlineAttr::Always {
2955 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
2956 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
2957 tcx.struct_span_lint_hir(
2958 lint::builtin::INLINE_NO_SANITIZE,
2962 lint.build("`no_sanitize` will have no effect after inlining")
2963 .span_note(inline_span, "inlining requested here")
2971 // Weak lang items have the same semantics as "std internal" symbols in the
2972 // sense that they're preserved through all our LTO passes and only
2973 // strippable by the linker.
2975 // Additionally weak lang items have predetermined symbol names.
2976 if tcx.is_weak_lang_item(id) {
2977 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2979 let check_name = |attr, sym| tcx.sess.check_name(attr, sym);
2980 if let Some(name) = weak_lang_items::link_name(check_name, &attrs) {
2981 codegen_fn_attrs.export_name = Some(name);
2982 codegen_fn_attrs.link_name = Some(name);
2984 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2986 // Internal symbols to the standard library all have no_mangle semantics in
2987 // that they have defined symbol names present in the function name. This
2988 // also applies to weak symbols where they all have known symbol names.
2989 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2990 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2996 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
2997 /// applied to the method prototype.
2998 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2999 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
3000 if let ty::AssocItemContainer::ImplContainer(impl_def_id) = impl_item.container {
3001 if let Some(trait_def_id) = tcx.trait_id_of_impl(impl_def_id) {
3002 if let Some(trait_item) = tcx
3003 .associated_items(trait_def_id)
3004 .filter_by_name_unhygienic(impl_item.ident.name)
3005 .find(move |trait_item| {
3006 trait_item.kind == ty::AssocKind::Fn
3007 && tcx.hygienic_eq(impl_item.ident, trait_item.ident, trait_def_id)
3011 .codegen_fn_attrs(trait_item.def_id)
3013 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3022 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
3023 use rustc_ast::{Lit, LitIntType, LitKind};
3024 let meta_item_list = attr.meta_item_list();
3025 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3026 let sole_meta_list = match meta_item_list {
3027 Some([item]) => item.literal(),
3030 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3031 if *ordinal <= usize::MAX as u128 {
3032 Some(*ordinal as usize)
3034 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3036 .struct_span_err(attr.span, &msg)
3037 .note("the value may not exceed `usize::MAX`")
3043 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3044 .note("an unsuffixed integer value, e.g., `1`, is expected")
3050 fn check_link_name_xor_ordinal(
3052 codegen_fn_attrs: &CodegenFnAttrs,
3053 inline_span: Option<Span>,
3055 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3058 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3059 if let Some(span) = inline_span {
3060 tcx.sess.span_err(span, msg);
3066 /// Checks the function annotated with `#[target_feature]` is not a safe
3067 /// trait method implementation, reporting an error if it is.
3068 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3069 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3070 let node = tcx.hir().get(hir_id);
3071 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3072 let parent_id = tcx.hir().get_parent_item(hir_id);
3073 let parent_item = tcx.hir().expect_item(parent_id);
3074 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3078 "`#[target_feature(..)]` cannot be applied to safe trait method",
3080 .span_label(attr_span, "cannot be applied to safe trait method")
3081 .span_label(tcx.def_span(id), "not an `unsafe` function")