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;
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, DiagnosticBuilder, ErrorGuaranteed};
31 use rustc_hir::def::{CtorKind, DefKind};
32 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
33 use rustc_hir::intravisit::{self, Visitor};
34 use rustc_hir::weak_lang_items;
35 use rustc_hir::{GenericParamKind, HirId, Node};
36 use rustc_middle::hir::nested_filter;
37 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
38 use rustc_middle::mir::mono::Linkage;
39 use rustc_middle::ty::query::Providers;
40 use rustc_middle::ty::subst::InternalSubsts;
41 use rustc_middle::ty::util::Discr;
42 use rustc_middle::ty::util::IntTypeExt;
43 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
44 use rustc_middle::ty::{ReprOptions, ToPredicate, TypeFoldable};
45 use rustc_session::lint;
46 use rustc_session::parse::feature_err;
47 use rustc_span::symbol::{kw, sym, Ident, Symbol};
48 use rustc_span::{Span, DUMMY_SP};
49 use rustc_target::spec::{abi, PanicStrategy, SanitizerSet};
50 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
56 struct OnlySelfBounds(bool);
58 ///////////////////////////////////////////////////////////////////////////
61 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
62 tcx.hir().visit_item_likes_in_module(
64 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
68 pub fn provide(providers: &mut Providers) {
69 *providers = Providers {
70 opt_const_param_of: type_of::opt_const_param_of,
71 type_of: type_of::type_of,
72 item_bounds: item_bounds::item_bounds,
73 explicit_item_bounds: item_bounds::explicit_item_bounds,
76 predicates_defined_on,
77 explicit_predicates_of,
79 super_predicates_that_define_assoc_type,
80 trait_explicit_predicates_and_bounds,
81 type_param_predicates,
91 collect_mod_item_types,
92 should_inherit_track_caller,
97 ///////////////////////////////////////////////////////////////////////////
99 /// Context specific to some particular item. This is what implements
100 /// `AstConv`. It has information about the predicates that are defined
101 /// on the trait. Unfortunately, this predicate information is
102 /// available in various different forms at various points in the
103 /// process. So we can't just store a pointer to e.g., the AST or the
104 /// parsed ty form, we have to be more flexible. To this end, the
105 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
106 /// `get_type_parameter_bounds` requests, drawing the information from
107 /// the AST (`hir::Generics`), recursively.
108 pub struct ItemCtxt<'tcx> {
113 ///////////////////////////////////////////////////////////////////////////
116 crate struct HirPlaceholderCollector(crate Vec<Span>);
118 impl<'v> Visitor<'v> for HirPlaceholderCollector {
119 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
120 if let hir::TyKind::Infer = t.kind {
123 intravisit::walk_ty(self, t)
125 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
127 hir::GenericArg::Infer(inf) => {
128 self.0.push(inf.span);
129 intravisit::walk_inf(self, inf);
131 hir::GenericArg::Type(t) => self.visit_ty(t),
135 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
136 if let &hir::ArrayLen::Infer(_, span) = length {
139 intravisit::walk_array_len(self, length)
143 struct CollectItemTypesVisitor<'tcx> {
147 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
148 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
149 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
150 crate fn placeholder_type_error<'tcx>(
153 generics: &[hir::GenericParam<'_>],
154 placeholder_types: Vec<Span>,
156 hir_ty: Option<&hir::Ty<'_>>,
159 if placeholder_types.is_empty() {
163 let type_name = generics.next_type_param_name(None);
164 let mut sugg: Vec<_> =
165 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
167 if generics.is_empty() {
168 if let Some(span) = span {
169 sugg.push((span, format!("<{}>", type_name)));
171 } else if let Some(arg) = generics
173 .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
175 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
176 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
177 sugg.push((arg.span, (*type_name).to_string()));
179 let last = generics.iter().last().unwrap();
180 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
181 let span = last.bounds_span_for_suggestions().unwrap_or(last.span.shrink_to_hi());
182 sugg.push((span, format!(", {}", type_name)));
185 let mut err = bad_placeholder(tcx, placeholder_types, kind);
187 // Suggest, but only if it is not a function in const or static
189 let mut is_fn = false;
190 let mut is_const_or_static = false;
192 if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind {
195 // Check if parent is const or static
196 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
197 let parent_node = tcx.hir().get(parent_id);
199 is_const_or_static = matches!(
201 Node::Item(&hir::Item {
202 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
204 }) | Node::TraitItem(&hir::TraitItem {
205 kind: hir::TraitItemKind::Const(..),
207 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
211 // if function is wrapped around a const or static,
212 // then don't show the suggestion
213 if !(is_fn && is_const_or_static) {
214 err.multipart_suggestion(
215 "use type parameters instead",
217 Applicability::HasPlaceholders,
224 fn reject_placeholder_type_signatures_in_item<'tcx>(
226 item: &'tcx hir::Item<'tcx>,
228 let (generics, suggest) = match &item.kind {
229 hir::ItemKind::Union(_, generics)
230 | hir::ItemKind::Enum(_, generics)
231 | hir::ItemKind::TraitAlias(generics, _)
232 | hir::ItemKind::Trait(_, _, generics, ..)
233 | hir::ItemKind::Impl(hir::Impl { generics, .. })
234 | hir::ItemKind::Struct(_, generics) => (generics, true),
235 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
236 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
237 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
241 let mut visitor = HirPlaceholderCollector::default();
242 visitor.visit_item(item);
244 placeholder_type_error(
255 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
256 type NestedFilter = nested_filter::OnlyBodies;
258 fn nested_visit_map(&mut self) -> Self::Map {
262 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
263 convert_item(self.tcx, item.item_id());
264 reject_placeholder_type_signatures_in_item(self.tcx, item);
265 intravisit::walk_item(self, item);
268 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
269 for param in generics.params {
271 hir::GenericParamKind::Lifetime { .. } => {}
272 hir::GenericParamKind::Type { default: Some(_), .. } => {
273 let def_id = self.tcx.hir().local_def_id(param.hir_id);
274 self.tcx.ensure().type_of(def_id);
276 hir::GenericParamKind::Type { .. } => {}
277 hir::GenericParamKind::Const { default, .. } => {
278 let def_id = self.tcx.hir().local_def_id(param.hir_id);
279 self.tcx.ensure().type_of(def_id);
280 if let Some(default) = default {
281 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
282 // need to store default and type of default
283 self.tcx.ensure().type_of(default_def_id);
284 self.tcx.ensure().const_param_default(def_id);
289 intravisit::walk_generics(self, generics);
292 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
293 if let hir::ExprKind::Closure(..) = expr.kind {
294 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
295 self.tcx.ensure().generics_of(def_id);
296 // We do not call `type_of` for closures here as that
297 // depends on typecheck and would therefore hide
298 // any further errors in case one typeck fails.
300 intravisit::walk_expr(self, expr);
303 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
304 convert_trait_item(self.tcx, trait_item.trait_item_id());
305 intravisit::walk_trait_item(self, trait_item);
308 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
309 convert_impl_item(self.tcx, impl_item.impl_item_id());
310 intravisit::walk_impl_item(self, impl_item);
314 ///////////////////////////////////////////////////////////////////////////
315 // Utility types and common code for the above passes.
317 fn bad_placeholder<'tcx>(
319 mut spans: Vec<Span>,
321 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
322 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
325 let mut err = struct_span_err!(
329 "the placeholder `_` is not allowed within types on item signatures for {}",
333 err.span_label(span, "not allowed in type signatures");
338 impl<'tcx> ItemCtxt<'tcx> {
339 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
340 ItemCtxt { tcx, item_def_id }
343 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
344 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
347 pub fn hir_id(&self) -> hir::HirId {
348 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
351 pub fn node(&self) -> hir::Node<'tcx> {
352 self.tcx.hir().get(self.hir_id())
356 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
357 fn tcx(&self) -> TyCtxt<'tcx> {
361 fn item_def_id(&self) -> Option<DefId> {
362 Some(self.item_def_id)
365 fn get_type_parameter_bounds(
370 ) -> ty::GenericPredicates<'tcx> {
371 self.tcx.at(span).type_param_predicates((
373 def_id.expect_local(),
378 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
382 fn allow_ty_infer(&self) -> bool {
386 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
387 self.tcx().ty_error_with_message(span, "bad placeholder type")
390 fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
391 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match *r {
392 ty::ReErased => self.tcx.lifetimes.re_static,
395 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
398 fn projected_ty_from_poly_trait_ref(
402 item_segment: &hir::PathSegment<'_>,
403 poly_trait_ref: ty::PolyTraitRef<'tcx>,
405 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
406 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
414 self.tcx().mk_projection(item_def_id, item_substs)
416 // There are no late-bound regions; we can just ignore the binder.
417 let mut err = struct_span_err!(
421 "cannot use the associated type of a trait \
422 with uninferred generic parameters"
426 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
428 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
430 hir::ItemKind::Enum(_, generics)
431 | hir::ItemKind::Struct(_, generics)
432 | hir::ItemKind::Union(_, generics) => {
433 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
434 let (lt_sp, sugg) = match generics.params {
435 [] => (generics.span, format!("<{}>", lt_name)),
437 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
440 let suggestions = vec![
443 span.with_hi(item_segment.ident.span.lo()),
446 // Replace the existing lifetimes with a new named lifetime.
448 .replace_late_bound_regions(poly_trait_ref, |_| {
449 self.tcx.mk_region(ty::ReEarlyBound(
450 ty::EarlyBoundRegion {
453 name: Symbol::intern(<_name),
461 err.multipart_suggestion(
462 "use a fully qualified path with explicit lifetimes",
464 Applicability::MaybeIncorrect,
470 hir::Node::Item(hir::Item {
472 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
476 | hir::Node::ForeignItem(_)
477 | hir::Node::TraitItem(_)
478 | hir::Node::ImplItem(_) => {
479 err.span_suggestion_verbose(
480 span.with_hi(item_segment.ident.span.lo()),
481 "use a fully qualified path with inferred lifetimes",
484 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
485 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
487 Applicability::MaybeIncorrect,
493 self.tcx().ty_error()
497 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
498 // Types in item signatures are not normalized to avoid undue dependencies.
502 fn set_tainted_by_errors(&self) {
503 // There's no obvious place to track this, so just let it go.
506 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
507 // There's no place to record types from signatures?
511 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
512 fn get_new_lifetime_name<'tcx>(
514 poly_trait_ref: ty::PolyTraitRef<'tcx>,
515 generics: &hir::Generics<'tcx>,
517 let existing_lifetimes = tcx
518 .collect_referenced_late_bound_regions(&poly_trait_ref)
521 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
522 Some(name.as_str().to_string())
527 .chain(generics.params.iter().filter_map(|param| {
528 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
529 Some(param.name.ident().as_str().to_string())
534 .collect::<FxHashSet<String>>();
536 let a_to_z_repeat_n = |n| {
537 (b'a'..=b'z').map(move |c| {
538 let mut s = '\''.to_string();
539 s.extend(std::iter::repeat(char::from(c)).take(n));
544 // If all single char lifetime names are present, we wrap around and double the chars.
545 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
548 /// Returns the predicates defined on `item_def_id` of the form
549 /// `X: Foo` where `X` is the type parameter `def_id`.
550 fn type_param_predicates(
552 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
553 ) -> ty::GenericPredicates<'_> {
556 // In the AST, bounds can derive from two places. Either
557 // written inline like `<T: Foo>` or in a where-clause like
560 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
561 let param_owner = tcx.hir().ty_param_owner(def_id);
562 let generics = tcx.generics_of(param_owner);
563 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
564 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
566 // Don't look for bounds where the type parameter isn't in scope.
567 let parent = if item_def_id == param_owner.to_def_id() {
570 tcx.generics_of(item_def_id).parent
573 let mut result = parent
575 let icx = ItemCtxt::new(tcx, parent);
576 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
578 .unwrap_or_default();
579 let mut extend = None;
581 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
582 let ast_generics = match tcx.hir().get(item_hir_id) {
583 Node::TraitItem(item) => &item.generics,
585 Node::ImplItem(item) => &item.generics,
587 Node::Item(item) => {
589 ItemKind::Fn(.., ref generics, _)
590 | ItemKind::Impl(hir::Impl { ref generics, .. })
591 | ItemKind::TyAlias(_, ref generics)
592 | ItemKind::OpaqueTy(OpaqueTy {
594 origin: hir::OpaqueTyOrigin::TyAlias,
597 | ItemKind::Enum(_, ref generics)
598 | ItemKind::Struct(_, ref generics)
599 | ItemKind::Union(_, ref generics) => generics,
600 ItemKind::Trait(_, _, ref generics, ..) => {
601 // Implied `Self: Trait` and supertrait bounds.
602 if param_id == item_hir_id {
603 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
605 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
613 Node::ForeignItem(item) => match item.kind {
614 ForeignItemKind::Fn(_, _, ref generics) => generics,
621 let icx = ItemCtxt::new(tcx, item_def_id);
622 let extra_predicates = extend.into_iter().chain(
623 icx.type_parameter_bounds_in_generics(
627 OnlySelfBounds(true),
631 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
632 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
637 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
641 impl<'tcx> ItemCtxt<'tcx> {
642 /// Finds bounds from `hir::Generics`. This requires scanning through the
643 /// AST. We do this to avoid having to convert *all* the bounds, which
644 /// would create artificial cycles. Instead, we can only convert the
645 /// bounds for a type parameter `X` if `X::Foo` is used.
646 fn type_parameter_bounds_in_generics(
648 ast_generics: &'tcx hir::Generics<'tcx>,
649 param_id: hir::HirId,
651 only_self_bounds: OnlySelfBounds,
652 assoc_name: Option<Ident>,
653 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
654 let from_ty_params = ast_generics
657 .filter_map(|param| match param.kind {
658 GenericParamKind::Type { .. } | GenericParamKind::Const { .. }
659 if param.hir_id == param_id =>
665 .flat_map(|bounds| bounds.iter())
666 .filter(|b| match assoc_name {
667 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
670 .flat_map(|b| predicates_from_bound(self, ty, b, ty::List::empty()));
672 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
673 let from_where_clauses = ast_generics
677 .filter_map(|wp| match *wp {
678 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
682 let bt = if bp.is_param_bound(param_def_id) {
684 } else if !only_self_bounds.0 {
685 Some(self.to_ty(bp.bounded_ty))
689 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
693 .filter(|b| match assoc_name {
694 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
697 .filter_map(move |b| bt.map(|bt| (bt, b, bvars)))
699 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars));
701 from_ty_params.chain(from_where_clauses).collect()
704 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
705 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
708 hir::GenericBound::Trait(poly_trait_ref, _) => {
709 let trait_ref = &poly_trait_ref.trait_ref;
710 if let Some(trait_did) = trait_ref.trait_def_id() {
711 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
721 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
722 let it = tcx.hir().item(item_id);
723 debug!("convert: item {} with id {}", it.ident, it.hir_id());
724 let def_id = item_id.def_id;
727 // These don't define types.
728 hir::ItemKind::ExternCrate(_)
729 | hir::ItemKind::Use(..)
730 | hir::ItemKind::Macro(..)
731 | hir::ItemKind::Mod(_)
732 | hir::ItemKind::GlobalAsm(_) => {}
733 hir::ItemKind::ForeignMod { items, .. } => {
735 let item = tcx.hir().foreign_item(item.id);
736 tcx.ensure().generics_of(item.def_id);
737 tcx.ensure().type_of(item.def_id);
738 tcx.ensure().predicates_of(item.def_id);
740 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
741 hir::ForeignItemKind::Static(..) => {
742 let mut visitor = HirPlaceholderCollector::default();
743 visitor.visit_foreign_item(item);
744 placeholder_type_error(
758 hir::ItemKind::Enum(ref enum_definition, _) => {
759 tcx.ensure().generics_of(def_id);
760 tcx.ensure().type_of(def_id);
761 tcx.ensure().predicates_of(def_id);
762 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
764 hir::ItemKind::Impl { .. } => {
765 tcx.ensure().generics_of(def_id);
766 tcx.ensure().type_of(def_id);
767 tcx.ensure().impl_trait_ref(def_id);
768 tcx.ensure().predicates_of(def_id);
770 hir::ItemKind::Trait(..) => {
771 tcx.ensure().generics_of(def_id);
772 tcx.ensure().trait_def(def_id);
773 tcx.at(it.span).super_predicates_of(def_id);
774 tcx.ensure().predicates_of(def_id);
776 hir::ItemKind::TraitAlias(..) => {
777 tcx.ensure().generics_of(def_id);
778 tcx.at(it.span).super_predicates_of(def_id);
779 tcx.ensure().predicates_of(def_id);
781 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
782 tcx.ensure().generics_of(def_id);
783 tcx.ensure().type_of(def_id);
784 tcx.ensure().predicates_of(def_id);
786 for f in struct_def.fields() {
787 let def_id = tcx.hir().local_def_id(f.hir_id);
788 tcx.ensure().generics_of(def_id);
789 tcx.ensure().type_of(def_id);
790 tcx.ensure().predicates_of(def_id);
793 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
794 convert_variant_ctor(tcx, ctor_hir_id);
798 // Desugared from `impl Trait`, so visited by the function's return type.
799 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
800 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
804 // Don't call `type_of` on opaque types, since that depends on type
805 // checking function bodies. `check_item_type` ensures that it's called
807 hir::ItemKind::OpaqueTy(..) => {
808 tcx.ensure().generics_of(def_id);
809 tcx.ensure().predicates_of(def_id);
810 tcx.ensure().explicit_item_bounds(def_id);
812 hir::ItemKind::TyAlias(..)
813 | hir::ItemKind::Static(..)
814 | hir::ItemKind::Const(..)
815 | hir::ItemKind::Fn(..) => {
816 tcx.ensure().generics_of(def_id);
817 tcx.ensure().type_of(def_id);
818 tcx.ensure().predicates_of(def_id);
820 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
821 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
822 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
823 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
824 if let hir::TyKind::TraitObject(..) = ty.kind {
825 let mut visitor = HirPlaceholderCollector::default();
826 visitor.visit_item(it);
827 placeholder_type_error(
844 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
845 let trait_item = tcx.hir().trait_item(trait_item_id);
846 tcx.ensure().generics_of(trait_item_id.def_id);
848 match trait_item.kind {
849 hir::TraitItemKind::Fn(..) => {
850 tcx.ensure().type_of(trait_item_id.def_id);
851 tcx.ensure().fn_sig(trait_item_id.def_id);
854 hir::TraitItemKind::Const(.., Some(_)) => {
855 tcx.ensure().type_of(trait_item_id.def_id);
858 hir::TraitItemKind::Const(..) => {
859 tcx.ensure().type_of(trait_item_id.def_id);
860 // Account for `const C: _;`.
861 let mut visitor = HirPlaceholderCollector::default();
862 visitor.visit_trait_item(trait_item);
863 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
866 hir::TraitItemKind::Type(_, Some(_)) => {
867 tcx.ensure().item_bounds(trait_item_id.def_id);
868 tcx.ensure().type_of(trait_item_id.def_id);
869 // Account for `type T = _;`.
870 let mut visitor = HirPlaceholderCollector::default();
871 visitor.visit_trait_item(trait_item);
872 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
875 hir::TraitItemKind::Type(_, None) => {
876 tcx.ensure().item_bounds(trait_item_id.def_id);
877 // #74612: Visit and try to find bad placeholders
878 // even if there is no concrete type.
879 let mut visitor = HirPlaceholderCollector::default();
880 visitor.visit_trait_item(trait_item);
882 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
886 tcx.ensure().predicates_of(trait_item_id.def_id);
889 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
890 let def_id = impl_item_id.def_id;
891 tcx.ensure().generics_of(def_id);
892 tcx.ensure().type_of(def_id);
893 tcx.ensure().predicates_of(def_id);
894 let impl_item = tcx.hir().impl_item(impl_item_id);
895 match impl_item.kind {
896 hir::ImplItemKind::Fn(..) => {
897 tcx.ensure().fn_sig(def_id);
899 hir::ImplItemKind::TyAlias(_) => {
900 // Account for `type T = _;`
901 let mut visitor = HirPlaceholderCollector::default();
902 visitor.visit_impl_item(impl_item);
904 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
906 hir::ImplItemKind::Const(..) => {}
910 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
911 let def_id = tcx.hir().local_def_id(ctor_id);
912 tcx.ensure().generics_of(def_id);
913 tcx.ensure().type_of(def_id);
914 tcx.ensure().predicates_of(def_id);
917 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
918 let def = tcx.adt_def(def_id);
919 let repr_type = def.repr().discr_type();
920 let initial = repr_type.initial_discriminant(tcx);
921 let mut prev_discr = None::<Discr<'_>>;
923 // fill the discriminant values and field types
924 for variant in variants {
925 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
927 if let Some(ref e) = variant.disr_expr {
928 let expr_did = tcx.hir().local_def_id(e.hir_id);
929 def.eval_explicit_discr(tcx, expr_did.to_def_id())
930 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
933 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
936 format!("overflowed on value after {}", prev_discr.unwrap()),
939 "explicitly set `{} = {}` if that is desired outcome",
940 variant.ident, wrapped_discr
945 .unwrap_or(wrapped_discr),
948 for f in variant.data.fields() {
949 let def_id = tcx.hir().local_def_id(f.hir_id);
950 tcx.ensure().generics_of(def_id);
951 tcx.ensure().type_of(def_id);
952 tcx.ensure().predicates_of(def_id);
955 // Convert the ctor, if any. This also registers the variant as
957 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
958 convert_variant_ctor(tcx, ctor_hir_id);
965 variant_did: Option<LocalDefId>,
966 ctor_did: Option<LocalDefId>,
968 discr: ty::VariantDiscr,
969 def: &hir::VariantData<'_>,
970 adt_kind: ty::AdtKind,
971 parent_did: LocalDefId,
972 ) -> ty::VariantDef {
973 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
978 let fid = tcx.hir().local_def_id(f.hir_id);
979 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
980 if let Some(prev_span) = dup_span {
981 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
987 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
990 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
993 let recovered = match def {
994 hir::VariantData::Struct(_, r) => *r,
999 variant_did.map(LocalDefId::to_def_id),
1000 ctor_did.map(LocalDefId::to_def_id),
1003 CtorKind::from_hir(def),
1005 parent_did.to_def_id(),
1007 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1008 || variant_did.map_or(false, |variant_did| {
1009 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1014 fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
1017 let def_id = def_id.expect_local();
1018 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1019 let Node::Item(item) = tcx.hir().get(hir_id) else {
1023 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1024 let (kind, variants) = match item.kind {
1025 ItemKind::Enum(ref def, _) => {
1026 let mut distance_from_explicit = 0;
1031 let variant_did = Some(tcx.hir().local_def_id(v.id));
1033 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1035 let discr = if let Some(ref e) = v.disr_expr {
1036 distance_from_explicit = 0;
1037 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1039 ty::VariantDiscr::Relative(distance_from_explicit)
1041 distance_from_explicit += 1;
1056 (AdtKind::Enum, variants)
1058 ItemKind::Struct(ref def, _) => {
1059 let variant_did = None::<LocalDefId>;
1060 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1062 let variants = std::iter::once(convert_variant(
1067 ty::VariantDiscr::Relative(0),
1074 (AdtKind::Struct, variants)
1076 ItemKind::Union(ref def, _) => {
1077 let variant_did = None;
1078 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1080 let variants = std::iter::once(convert_variant(
1085 ty::VariantDiscr::Relative(0),
1092 (AdtKind::Union, variants)
1096 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1099 /// Ensures that the super-predicates of the trait with a `DefId`
1100 /// of `trait_def_id` are converted and stored. This also ensures that
1101 /// the transitive super-predicates are converted.
1102 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1103 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1104 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1107 /// Ensures that the super-predicates of the trait with a `DefId`
1108 /// of `trait_def_id` are converted and stored. This also ensures that
1109 /// the transitive super-predicates are converted.
1110 fn super_predicates_that_define_assoc_type(
1112 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1113 ) -> ty::GenericPredicates<'_> {
1115 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1116 trait_def_id, assoc_name
1118 if trait_def_id.is_local() {
1119 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1120 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1122 let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
1123 bug!("trait_node_id {} is not an item", trait_hir_id);
1126 let (generics, bounds) = match item.kind {
1127 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1128 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1129 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1132 let icx = ItemCtxt::new(tcx, trait_def_id);
1134 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1135 let self_param_ty = tcx.types.self_param;
1136 let superbounds1 = if let Some(assoc_name) = assoc_name {
1137 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1144 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1147 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1149 // Convert any explicit superbounds in the where-clause,
1150 // e.g., `trait Foo where Self: Bar`.
1151 // In the case of trait aliases, however, we include all bounds in the where-clause,
1152 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1153 // as one of its "superpredicates".
1154 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1155 let superbounds2 = icx.type_parameter_bounds_in_generics(
1159 OnlySelfBounds(!is_trait_alias),
1163 // Combine the two lists to form the complete set of superbounds:
1164 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1166 // Now require that immediate supertraits are converted,
1167 // which will, in turn, reach indirect supertraits.
1168 if assoc_name.is_none() {
1169 // Now require that immediate supertraits are converted,
1170 // which will, in turn, reach indirect supertraits.
1171 for &(pred, span) in superbounds {
1172 debug!("superbound: {:?}", pred);
1173 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1174 tcx.at(span).super_predicates_of(bound.def_id());
1179 ty::GenericPredicates { parent: None, predicates: superbounds }
1181 // if `assoc_name` is None, then the query should've been redirected to an
1182 // external provider
1183 assert!(assoc_name.is_some());
1184 tcx.super_predicates_of(trait_def_id)
1188 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1189 let item = tcx.hir().expect_item(def_id.expect_local());
1191 let (is_auto, unsafety, items) = match item.kind {
1192 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1193 (is_auto == hir::IsAuto::Yes, unsafety, items)
1195 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1196 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1199 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1200 if paren_sugar && !tcx.features().unboxed_closures {
1204 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1205 which traits can use parenthetical notation",
1207 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1211 let is_marker = tcx.has_attr(def_id, sym::marker);
1212 let skip_array_during_method_dispatch =
1213 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1214 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1215 ty::trait_def::TraitSpecializationKind::Marker
1216 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1217 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1219 ty::trait_def::TraitSpecializationKind::None
1221 let must_implement_one_of = tcx
1224 .find(|attr| attr.has_name(sym::rustc_must_implement_one_of))
1225 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1226 // and that they are all identifiers
1227 .and_then(|attr| match attr.meta_item_list() {
1228 Some(items) if items.len() < 2 => {
1232 "the `#[rustc_must_implement_one_of]` attribute must be \
1233 used with at least 2 args",
1239 Some(items) => items
1241 .map(|item| item.ident().ok_or(item.span()))
1242 .collect::<Result<Box<[_]>, _>>()
1245 .struct_span_err(span, "must be a name of an associated function")
1249 .zip(Some(attr.span)),
1250 // Error is reported by `rustc_attr!`
1253 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1254 // functions in the trait with default implementations
1255 .and_then(|(list, attr_span)| {
1256 let errors = list.iter().filter_map(|ident| {
1257 let item = items.iter().find(|item| item.ident == *ident);
1260 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1261 if !item.defaultness.has_value() {
1265 "This function doesn't have a default implementation",
1267 .span_note(attr_span, "required by this annotation")
1277 .struct_span_err(item.span, "Not a function")
1278 .span_note(attr_span, "required by this annotation")
1280 "All `#[rustc_must_implement_one_of]` arguments \
1281 must be associated function names",
1287 .struct_span_err(ident.span, "Function not found in this trait")
1295 (errors.count() == 0).then_some(list)
1297 // Check for duplicates
1299 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1300 let mut no_dups = true;
1302 for ident in &*list {
1303 if let Some(dup) = set.insert(ident.name, ident.span) {
1305 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1307 "All `#[rustc_must_implement_one_of]` arguments \
1316 no_dups.then_some(list)
1325 skip_array_during_method_dispatch,
1327 must_implement_one_of,
1331 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1332 struct LateBoundRegionsDetector<'tcx> {
1334 outer_index: ty::DebruijnIndex,
1335 has_late_bound_regions: Option<Span>,
1338 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1339 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1340 if self.has_late_bound_regions.is_some() {
1344 hir::TyKind::BareFn(..) => {
1345 self.outer_index.shift_in(1);
1346 intravisit::walk_ty(self, ty);
1347 self.outer_index.shift_out(1);
1349 _ => intravisit::walk_ty(self, ty),
1353 fn visit_poly_trait_ref(
1355 tr: &'tcx hir::PolyTraitRef<'tcx>,
1356 m: hir::TraitBoundModifier,
1358 if self.has_late_bound_regions.is_some() {
1361 self.outer_index.shift_in(1);
1362 intravisit::walk_poly_trait_ref(self, tr, m);
1363 self.outer_index.shift_out(1);
1366 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1367 if self.has_late_bound_regions.is_some() {
1371 match self.tcx.named_region(lt.hir_id) {
1372 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1374 rl::Region::LateBound(debruijn, _, _)
1375 | rl::Region::LateBoundAnon(debruijn, _, _),
1376 ) if debruijn < self.outer_index => {}
1378 rl::Region::LateBound(..)
1379 | rl::Region::LateBoundAnon(..)
1380 | rl::Region::Free(..),
1383 self.has_late_bound_regions = Some(lt.span);
1389 fn has_late_bound_regions<'tcx>(
1392 generics: &'tcx hir::Generics<'tcx>,
1393 decl: &'tcx hir::FnDecl<'tcx>,
1395 let mut visitor = LateBoundRegionsDetector {
1397 outer_index: ty::INNERMOST,
1398 has_late_bound_regions: None,
1400 let late_bound_map = tcx.is_late_bound_map(def_id);
1401 let is_late_bound = |id| {
1402 let id = tcx.hir().local_def_id(id);
1403 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
1405 for param in generics.params {
1406 if let GenericParamKind::Lifetime { .. } = param.kind {
1407 if is_late_bound(param.hir_id) {
1408 return Some(param.span);
1412 visitor.visit_fn_decl(decl);
1413 visitor.has_late_bound_regions
1417 Node::TraitItem(item) => match item.kind {
1418 hir::TraitItemKind::Fn(ref sig, _) => {
1419 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1423 Node::ImplItem(item) => match item.kind {
1424 hir::ImplItemKind::Fn(ref sig, _) => {
1425 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1429 Node::ForeignItem(item) => match item.kind {
1430 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1431 has_late_bound_regions(tcx, item.def_id, generics, fn_decl)
1435 Node::Item(item) => match item.kind {
1436 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1437 has_late_bound_regions(tcx, item.def_id, generics, sig.decl)
1445 struct AnonConstInParamTyDetector {
1447 found_anon_const_in_param_ty: bool,
1451 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1452 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1453 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1454 let prev = self.in_param_ty;
1455 self.in_param_ty = true;
1457 self.in_param_ty = prev;
1461 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1462 if self.in_param_ty && self.ct == c.hir_id {
1463 self.found_anon_const_in_param_ty = true;
1465 intravisit::walk_anon_const(self, c)
1470 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1473 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1475 let node = tcx.hir().get(hir_id);
1476 let parent_def_id = match node {
1478 | Node::TraitItem(_)
1481 | Node::Field(_) => {
1482 let parent_id = tcx.hir().get_parent_item(hir_id);
1483 Some(parent_id.to_def_id())
1485 // FIXME(#43408) always enable this once `lazy_normalization` is
1486 // stable enough and does not need a feature gate anymore.
1487 Node::AnonConst(_) => {
1488 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1490 let mut in_param_ty = false;
1491 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1492 if let Some(generics) = node.generics() {
1493 let mut visitor = AnonConstInParamTyDetector {
1495 found_anon_const_in_param_ty: false,
1499 visitor.visit_generics(generics);
1500 in_param_ty = visitor.found_anon_const_in_param_ty;
1506 // We do not allow generic parameters in anon consts if we are inside
1507 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1509 } else if tcx.lazy_normalization() {
1510 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1511 // If the def_id we are calling generics_of on is an anon ct default i.e:
1513 // struct Foo<const N: usize = { .. }>;
1514 // ^^^ ^ ^^^^^^ def id of this anon const
1518 // then we only want to return generics for params to the left of `N`. If we don't do that we
1519 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1521 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1522 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1523 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1525 // We fix this by having this function return the parent's generics ourselves and truncating the
1526 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1528 // For the above code example that means we want `substs: []`
1529 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1530 // the def id of the `{ N + 1 }` anon const
1531 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1533 // This has some implications for how we get the predicates available to the anon const
1534 // see `explicit_predicates_of` for more information on this
1535 let generics = tcx.generics_of(parent_def_id.to_def_id());
1536 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1537 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1538 // In the above example this would be .params[..N#0]
1539 let params = generics.params[..param_def_idx as usize].to_owned();
1540 let param_def_id_to_index =
1541 params.iter().map(|param| (param.def_id, param.index)).collect();
1543 return ty::Generics {
1544 // we set the parent of these generics to be our parent's parent so that we
1545 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1546 // struct Foo<const N: usize, const M: usize = { ... }>;
1547 parent: generics.parent,
1548 parent_count: generics.parent_count,
1550 param_def_id_to_index,
1551 has_self: generics.has_self,
1552 has_late_bound_regions: generics.has_late_bound_regions,
1556 // HACK(eddyb) this provides the correct generics when
1557 // `feature(generic_const_expressions)` is enabled, so that const expressions
1558 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1560 // Note that we do not supply the parent generics when using
1561 // `min_const_generics`.
1562 Some(parent_def_id.to_def_id())
1564 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1566 // HACK(eddyb) this provides the correct generics for repeat
1567 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1568 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1569 // as they shouldn't be able to cause query cycle errors.
1570 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1571 if constant.hir_id() == hir_id =>
1573 Some(parent_def_id.to_def_id())
1575 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1576 if constant.hir_id == hir_id =>
1578 Some(parent_def_id.to_def_id())
1580 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1581 Some(tcx.typeck_root_def_id(def_id))
1587 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1588 Some(tcx.typeck_root_def_id(def_id))
1590 Node::Item(item) => match item.kind {
1591 ItemKind::OpaqueTy(hir::OpaqueTy {
1593 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1595 }) => Some(fn_def_id.to_def_id()),
1596 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1597 let parent_id = tcx.hir().get_parent_item(hir_id);
1598 assert_ne!(parent_id, CRATE_DEF_ID);
1599 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1600 // Opaque types are always nested within another item, and
1601 // inherit the generics of the item.
1602 Some(parent_id.to_def_id())
1609 let mut opt_self = None;
1610 let mut allow_defaults = false;
1612 let no_generics = hir::Generics::empty();
1613 let ast_generics = match node {
1614 Node::TraitItem(item) => &item.generics,
1616 Node::ImplItem(item) => &item.generics,
1618 Node::Item(item) => {
1620 ItemKind::Fn(.., ref generics, _)
1621 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1623 ItemKind::TyAlias(_, ref generics)
1624 | ItemKind::Enum(_, ref generics)
1625 | ItemKind::Struct(_, ref generics)
1626 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1627 | ItemKind::Union(_, ref generics) => {
1628 allow_defaults = true;
1632 ItemKind::Trait(_, _, ref generics, ..)
1633 | ItemKind::TraitAlias(ref generics, ..) => {
1634 // Add in the self type parameter.
1636 // Something of a hack: use the node id for the trait, also as
1637 // the node id for the Self type parameter.
1638 let param_id = item.def_id;
1640 opt_self = Some(ty::GenericParamDef {
1642 name: kw::SelfUpper,
1643 def_id: param_id.to_def_id(),
1644 pure_wrt_drop: false,
1645 kind: ty::GenericParamDefKind::Type {
1647 object_lifetime_default: rl::Set1::Empty,
1652 allow_defaults = true;
1660 Node::ForeignItem(item) => match item.kind {
1661 ForeignItemKind::Static(..) => &no_generics,
1662 ForeignItemKind::Fn(_, _, ref generics) => generics,
1663 ForeignItemKind::Type => &no_generics,
1669 let has_self = opt_self.is_some();
1670 let mut parent_has_self = false;
1671 let mut own_start = has_self as u32;
1672 let parent_count = parent_def_id.map_or(0, |def_id| {
1673 let generics = tcx.generics_of(def_id);
1675 parent_has_self = generics.has_self;
1676 own_start = generics.count() as u32;
1677 generics.parent_count + generics.params.len()
1680 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1682 if let Some(opt_self) = opt_self {
1683 params.push(opt_self);
1686 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics);
1687 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1688 name: param.name.ident().name,
1689 index: own_start + i as u32,
1690 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1691 pure_wrt_drop: param.pure_wrt_drop,
1692 kind: ty::GenericParamDefKind::Lifetime,
1695 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id.owner);
1697 // Now create the real type and const parameters.
1698 let type_start = own_start - has_self as u32 + params.len() as u32;
1701 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1702 GenericParamKind::Lifetime { .. } => None,
1703 GenericParamKind::Type { ref default, synthetic, .. } => {
1704 if !allow_defaults && default.is_some() {
1705 if !tcx.features().default_type_parameter_fallback {
1706 tcx.struct_span_lint_hir(
1707 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1712 "defaults for type parameters are only allowed in \
1713 `struct`, `enum`, `type`, or `trait` definitions",
1721 let kind = ty::GenericParamDefKind::Type {
1722 has_default: default.is_some(),
1723 object_lifetime_default: object_lifetime_defaults
1725 .map_or(rl::Set1::Empty, |o| o[i]),
1729 let param_def = ty::GenericParamDef {
1730 index: type_start + i as u32,
1731 name: param.name.ident().name,
1732 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1733 pure_wrt_drop: param.pure_wrt_drop,
1739 GenericParamKind::Const { default, .. } => {
1740 if !allow_defaults && default.is_some() {
1743 "defaults for const parameters are only allowed in \
1744 `struct`, `enum`, `type`, or `trait` definitions",
1748 let param_def = ty::GenericParamDef {
1749 index: type_start + i as u32,
1750 name: param.name.ident().name,
1751 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1752 pure_wrt_drop: param.pure_wrt_drop,
1753 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1760 // provide junk type parameter defs - the only place that
1761 // cares about anything but the length is instantiation,
1762 // and we don't do that for closures.
1763 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1764 let dummy_args = if gen.is_some() {
1765 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1767 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1770 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1771 index: type_start + i as u32,
1772 name: Symbol::intern(arg),
1774 pure_wrt_drop: false,
1775 kind: ty::GenericParamDefKind::Type {
1777 object_lifetime_default: rl::Set1::Empty,
1783 // provide junk type parameter defs for const blocks.
1784 if let Node::AnonConst(_) = node {
1785 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1786 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1787 params.push(ty::GenericParamDef {
1789 name: Symbol::intern("<const_ty>"),
1791 pure_wrt_drop: false,
1792 kind: ty::GenericParamDefKind::Type {
1794 object_lifetime_default: rl::Set1::Empty,
1801 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1804 parent: parent_def_id,
1807 param_def_id_to_index,
1808 has_self: has_self || parent_has_self,
1809 has_late_bound_regions: has_late_bound_regions(tcx, node),
1813 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1814 generic_args.iter().any(|arg| match arg {
1815 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1816 hir::GenericArg::Infer(_) => true,
1821 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1822 /// use inference to provide suggestions for the appropriate type if possible.
1823 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1828 Slice(ty) => is_suggestable_infer_ty(ty),
1829 Array(ty, length) => {
1830 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1832 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1833 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1834 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1835 Path(hir::QPath::TypeRelative(ty, segment)) => {
1836 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1838 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1839 ty_opt.map_or(false, is_suggestable_infer_ty)
1840 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1846 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1847 if let hir::FnRetTy::Return(ty) = output {
1848 if is_suggestable_infer_ty(ty) {
1855 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1856 use rustc_hir::Node::*;
1859 let def_id = def_id.expect_local();
1860 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1862 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1864 match tcx.hir().get(hir_id) {
1865 TraitItem(hir::TraitItem {
1866 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1871 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1872 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1873 match get_infer_ret_ty(&sig.decl.output) {
1875 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1876 // Typeck doesn't expect erased regions to be returned from `type_of`.
1877 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match *r {
1878 ty::ReErased => tcx.lifetimes.re_static,
1881 let fn_sig = ty::Binder::dummy(fn_sig);
1883 let mut visitor = HirPlaceholderCollector::default();
1884 visitor.visit_ty(ty);
1885 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1886 let ret_ty = fn_sig.skip_binder().output();
1887 if !ret_ty.references_error() {
1888 if !ret_ty.is_closure() {
1889 let ret_ty_str = match ret_ty.kind() {
1890 // Suggest a function pointer return type instead of a unique function definition
1891 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1893 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1894 _ => ret_ty.to_string(),
1896 diag.span_suggestion(
1898 "replace with the correct return type",
1900 Applicability::MaybeIncorrect,
1903 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1904 // to prevent the user from getting a papercut while trying to use the unique closure
1905 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1906 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1907 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1914 None => <dyn AstConv<'_>>::ty_of_fn(
1917 sig.header.unsafety,
1927 TraitItem(hir::TraitItem {
1928 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1932 }) => <dyn AstConv<'_>>::ty_of_fn(
1943 ForeignItem(&hir::ForeignItem {
1944 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1946 let abi = tcx.hir().get_foreign_abi(hir_id);
1947 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1950 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1951 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1953 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1954 ty::Binder::dummy(tcx.mk_fn_sig(
1958 hir::Unsafety::Normal,
1963 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1964 // Closure signatures are not like other function
1965 // signatures and cannot be accessed through `fn_sig`. For
1966 // example, a closure signature excludes the `self`
1967 // argument. In any case they are embedded within the
1968 // closure type as part of the `ClosureSubsts`.
1970 // To get the signature of a closure, you should use the
1971 // `sig` method on the `ClosureSubsts`:
1973 // substs.as_closure().sig(def_id, tcx)
1975 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1980 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1985 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1986 let icx = ItemCtxt::new(tcx, def_id);
1987 match tcx.hir().expect_item(def_id.expect_local()).kind {
1988 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1989 let selfty = tcx.type_of(def_id);
1990 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1996 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1997 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1998 let item = tcx.hir().expect_item(def_id.expect_local());
2000 hir::ItemKind::Impl(hir::Impl {
2001 polarity: hir::ImplPolarity::Negative(span),
2005 if is_rustc_reservation {
2006 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
2007 tcx.sess.span_err(span, "reservation impls can't be negative");
2009 ty::ImplPolarity::Negative
2011 hir::ItemKind::Impl(hir::Impl {
2012 polarity: hir::ImplPolarity::Positive,
2016 if is_rustc_reservation {
2017 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2019 ty::ImplPolarity::Positive
2021 hir::ItemKind::Impl(hir::Impl {
2022 polarity: hir::ImplPolarity::Positive,
2026 if is_rustc_reservation {
2027 ty::ImplPolarity::Reservation
2029 ty::ImplPolarity::Positive
2032 item => bug!("impl_polarity: {:?} not an impl", item),
2036 /// Returns the early-bound lifetimes declared in this generics
2037 /// listing. For anything other than fns/methods, this is just all
2038 /// the lifetimes that are declared. For fns or methods, we have to
2039 /// screen out those that do not appear in any where-clauses etc using
2040 /// `resolve_lifetime::early_bound_lifetimes`.
2041 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2044 generics: &'a hir::Generics<'a>,
2045 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2046 let late_bound_map = if generics.params.is_empty() {
2047 // This function may be called on `def_id == CRATE_DEF_ID`,
2048 // which makes `is_late_bound_map` ICE. Don't even try if there
2049 // is no generic parameter.
2052 tcx.is_late_bound_map(def_id)
2054 let is_late_bound = move |hir_id| {
2055 let id = tcx.hir().local_def_id(hir_id);
2056 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
2058 generics.params.iter().filter(move |param| match param.kind {
2059 GenericParamKind::Lifetime { .. } => !is_late_bound(param.hir_id),
2064 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2065 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2066 /// inferred constraints concerning which regions outlive other regions.
2067 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2068 debug!("predicates_defined_on({:?})", def_id);
2069 let mut result = tcx.explicit_predicates_of(def_id);
2070 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2071 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2072 if !inferred_outlives.is_empty() {
2074 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2075 def_id, inferred_outlives,
2077 if result.predicates.is_empty() {
2078 result.predicates = inferred_outlives;
2080 result.predicates = tcx
2082 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2086 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2090 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2091 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2092 /// `Self: Trait` predicates for traits.
2093 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2094 let mut result = tcx.predicates_defined_on(def_id);
2096 if tcx.is_trait(def_id) {
2097 // For traits, add `Self: Trait` predicate. This is
2098 // not part of the predicates that a user writes, but it
2099 // is something that one must prove in order to invoke a
2100 // method or project an associated type.
2102 // In the chalk setup, this predicate is not part of the
2103 // "predicates" for a trait item. But it is useful in
2104 // rustc because if you directly (e.g.) invoke a trait
2105 // method like `Trait::method(...)`, you must naturally
2106 // prove that the trait applies to the types that were
2107 // used, and adding the predicate into this list ensures
2108 // that this is done.
2110 // We use a DUMMY_SP here as a way to signal trait bounds that come
2111 // from the trait itself that *shouldn't* be shown as the source of
2112 // an obligation and instead be skipped. Otherwise we'd use
2113 // `tcx.def_span(def_id);`
2114 let span = rustc_span::DUMMY_SP;
2116 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2117 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2121 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2125 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2126 /// N.B., this does not include any implied/inferred constraints.
2127 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2130 debug!("explicit_predicates_of(def_id={:?})", def_id);
2132 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2133 let node = tcx.hir().get(hir_id);
2135 let mut is_trait = None;
2136 let mut is_default_impl_trait = None;
2138 let icx = ItemCtxt::new(tcx, def_id);
2140 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2142 // We use an `IndexSet` to preserves order of insertion.
2143 // Preserving the order of insertion is important here so as not to break UI tests.
2144 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2146 let ast_generics = match node {
2147 Node::TraitItem(item) => &item.generics,
2149 Node::ImplItem(item) => &item.generics,
2151 Node::Item(item) => {
2153 ItemKind::Impl(ref impl_) => {
2154 if impl_.defaultness.is_default() {
2155 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2159 ItemKind::Fn(.., ref generics, _)
2160 | ItemKind::TyAlias(_, ref generics)
2161 | ItemKind::Enum(_, ref generics)
2162 | ItemKind::Struct(_, ref generics)
2163 | ItemKind::Union(_, ref generics) => generics,
2165 ItemKind::Trait(_, _, ref generics, ..) => {
2166 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2169 ItemKind::TraitAlias(ref generics, _) => {
2170 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2173 ItemKind::OpaqueTy(OpaqueTy {
2174 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2177 // return-position impl trait
2179 // We don't inherit predicates from the parent here:
2180 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2181 // then the return type is `f::<'static, T>::{{opaque}}`.
2183 // If we inherited the predicates of `f` then we would
2184 // require that `T: 'static` to show that the return
2185 // type is well-formed.
2187 // The only way to have something with this opaque type
2188 // is from the return type of the containing function,
2189 // which will ensure that the function's predicates
2191 return ty::GenericPredicates { parent: None, predicates: &[] };
2193 ItemKind::OpaqueTy(OpaqueTy {
2195 origin: hir::OpaqueTyOrigin::TyAlias,
2198 // type-alias impl trait
2206 Node::ForeignItem(item) => match item.kind {
2207 ForeignItemKind::Static(..) => NO_GENERICS,
2208 ForeignItemKind::Fn(_, _, ref generics) => generics,
2209 ForeignItemKind::Type => NO_GENERICS,
2215 let generics = tcx.generics_of(def_id);
2216 let parent_count = generics.parent_count as u32;
2217 let has_own_self = generics.has_self && parent_count == 0;
2219 // Below we'll consider the bounds on the type parameters (including `Self`)
2220 // and the explicit where-clauses, but to get the full set of predicates
2221 // on a trait we need to add in the supertrait bounds and bounds found on
2222 // associated types.
2223 if let Some(_trait_ref) = is_trait {
2224 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2227 // In default impls, we can assume that the self type implements
2228 // the trait. So in:
2230 // default impl Foo for Bar { .. }
2232 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2233 // (see below). Recall that a default impl is not itself an impl, but rather a
2234 // set of defaults that can be incorporated into another impl.
2235 if let Some(trait_ref) = is_default_impl_trait {
2236 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2239 // Collect the region predicates that were declared inline as
2240 // well. In the case of parameters declared on a fn or method, we
2241 // have to be careful to only iterate over early-bound regions.
2242 let mut index = parent_count + has_own_self as u32;
2243 for param in early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics) {
2244 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2245 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2247 name: param.name.ident().name,
2252 GenericParamKind::Lifetime { .. } => {
2253 param.bounds.iter().for_each(|bound| match bound {
2254 hir::GenericBound::Outlives(lt) => {
2255 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2256 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2257 predicates.insert((outlives.to_predicate(tcx), lt.span));
2266 // Collect the predicates that were written inline by the user on each
2267 // type parameter (e.g., `<T: Foo>`).
2268 for param in ast_generics.params {
2270 // We already dealt with early bound lifetimes above.
2271 GenericParamKind::Lifetime { .. } => (),
2272 GenericParamKind::Type { .. } => {
2273 let name = param.name.ident().name;
2274 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2277 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2278 // Params are implicitly sized unless a `?Sized` bound is found
2279 <dyn AstConv<'_>>::add_implicitly_sized(
2283 Some((param.hir_id, ast_generics.where_clause.predicates)),
2286 predicates.extend(bounds.predicates(tcx, param_ty));
2288 GenericParamKind::Const { .. } => {
2289 // Bounds on const parameters are currently not possible.
2290 debug_assert!(param.bounds.is_empty());
2296 // Add in the bounds that appear in the where-clause.
2297 let where_clause = &ast_generics.where_clause;
2298 for predicate in where_clause.predicates {
2300 hir::WherePredicate::BoundPredicate(bound_pred) => {
2301 let ty = icx.to_ty(bound_pred.bounded_ty);
2302 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2304 // Keep the type around in a dummy predicate, in case of no bounds.
2305 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2306 // is still checked for WF.
2307 if bound_pred.bounds.is_empty() {
2308 if let ty::Param(_) = ty.kind() {
2309 // This is a `where T:`, which can be in the HIR from the
2310 // transformation that moves `?Sized` to `T`'s declaration.
2311 // We can skip the predicate because type parameters are
2312 // trivially WF, but also we *should*, to avoid exposing
2313 // users who never wrote `where Type:,` themselves, to
2314 // compiler/tooling bugs from not handling WF predicates.
2316 let span = bound_pred.bounded_ty.span;
2317 let re_root_empty = tcx.lifetimes.re_root_empty;
2318 let predicate = ty::Binder::bind_with_vars(
2319 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2325 predicates.insert((predicate.to_predicate(tcx), span));
2329 let mut bounds = Bounds::default();
2330 <dyn AstConv<'_>>::add_bounds(
2333 bound_pred.bounds.iter(),
2337 predicates.extend(bounds.predicates(tcx, ty));
2340 hir::WherePredicate::RegionPredicate(region_pred) => {
2341 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2342 predicates.extend(region_pred.bounds.iter().map(|bound| {
2343 let (r2, span) = match bound {
2344 hir::GenericBound::Outlives(lt) => {
2345 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2349 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2350 ty::OutlivesPredicate(r1, r2),
2352 .to_predicate(icx.tcx);
2358 hir::WherePredicate::EqPredicate(..) => {
2364 if tcx.features().generic_const_exprs {
2365 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2368 let mut predicates: Vec<_> = predicates.into_iter().collect();
2370 // Subtle: before we store the predicates into the tcx, we
2371 // sort them so that predicates like `T: Foo<Item=U>` come
2372 // before uses of `U`. This avoids false ambiguity errors
2373 // in trait checking. See `setup_constraining_predicates`
2375 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2376 let self_ty = tcx.type_of(def_id);
2377 let trait_ref = tcx.impl_trait_ref(def_id);
2378 cgp::setup_constraining_predicates(
2382 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2386 let result = ty::GenericPredicates {
2387 parent: generics.parent,
2388 predicates: tcx.arena.alloc_from_iter(predicates),
2390 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2394 fn const_evaluatable_predicates_of<'tcx>(
2397 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2398 struct ConstCollector<'tcx> {
2400 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2403 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2404 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2405 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2406 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2407 if let ty::ConstKind::Unevaluated(uv) = ct.val() {
2408 assert_eq!(uv.promoted, None);
2409 let span = self.tcx.hir().span(c.hir_id);
2411 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2412 .to_predicate(self.tcx),
2418 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2419 // Do not look into const param defaults,
2420 // these get checked when they are actually instantiated.
2422 // We do not want the following to error:
2424 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2425 // struct Bar<const N: usize>(Foo<N, 3>);
2429 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2430 let node = tcx.hir().get(hir_id);
2432 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2433 if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
2434 if let Some(of_trait) = &impl_.of_trait {
2435 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2436 collector.visit_trait_ref(of_trait);
2439 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2440 collector.visit_ty(impl_.self_ty);
2443 if let Some(generics) = node.generics() {
2444 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2445 collector.visit_generics(generics);
2448 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2449 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2450 collector.visit_fn_decl(fn_sig.decl);
2452 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2457 fn trait_explicit_predicates_and_bounds(
2460 ) -> ty::GenericPredicates<'_> {
2461 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2462 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2465 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2466 let def_kind = tcx.def_kind(def_id);
2467 if let DefKind::Trait = def_kind {
2468 // Remove bounds on associated types from the predicates, they will be
2469 // returned by `explicit_item_bounds`.
2470 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2471 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2473 let is_assoc_item_ty = |ty: Ty<'_>| {
2474 // For a predicate from a where clause to become a bound on an
2476 // * It must use the identity substs of the item.
2477 // * Since any generic parameters on the item are not in scope,
2478 // this means that the item is not a GAT, and its identity
2479 // substs are the same as the trait's.
2480 // * It must be an associated type for this trait (*not* a
2482 if let ty::Projection(projection) = ty.kind() {
2483 projection.substs == trait_identity_substs
2484 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2490 let predicates: Vec<_> = predicates_and_bounds
2494 .filter(|(pred, _)| match pred.kind().skip_binder() {
2495 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2496 ty::PredicateKind::Projection(proj) => {
2497 !is_assoc_item_ty(proj.projection_ty.self_ty())
2499 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2503 if predicates.len() == predicates_and_bounds.predicates.len() {
2504 predicates_and_bounds
2506 ty::GenericPredicates {
2507 parent: predicates_and_bounds.parent,
2508 predicates: tcx.arena.alloc_slice(&predicates),
2512 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2513 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2514 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2515 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2516 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2517 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2519 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2520 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2521 // ^^^ explicit_predicates_of on
2522 // parent item we dont have set as the
2523 // parent of generics returned by `generics_of`
2525 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2526 let item_def_id = tcx.hir().get_parent_item(hir_id);
2527 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2528 return tcx.explicit_predicates_of(item_def_id);
2531 gather_explicit_predicates_of(tcx, def_id)
2535 /// Converts a specific `GenericBound` from the AST into a set of
2536 /// predicates that apply to the self type. A vector is returned
2537 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2538 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2539 /// and `<T as Bar>::X == i32`).
2540 fn predicates_from_bound<'tcx>(
2541 astconv: &dyn AstConv<'tcx>,
2543 bound: &'tcx hir::GenericBound<'tcx>,
2544 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2545 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2546 let mut bounds = Bounds::default();
2547 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2548 bounds.predicates(astconv.tcx(), param_ty).collect()
2551 fn compute_sig_of_foreign_fn_decl<'tcx>(
2554 decl: &'tcx hir::FnDecl<'tcx>,
2557 ) -> ty::PolyFnSig<'tcx> {
2558 let unsafety = if abi == abi::Abi::RustIntrinsic {
2559 intrinsic_operation_unsafety(tcx.item_name(def_id))
2561 hir::Unsafety::Unsafe
2563 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2564 let fty = <dyn AstConv<'_>>::ty_of_fn(
2565 &ItemCtxt::new(tcx, def_id),
2570 &hir::Generics::empty(),
2575 // Feature gate SIMD types in FFI, since I am not sure that the
2576 // ABIs are handled at all correctly. -huonw
2577 if abi != abi::Abi::RustIntrinsic
2578 && abi != abi::Abi::PlatformIntrinsic
2579 && !tcx.features().simd_ffi
2581 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2586 .span_to_snippet(ast_ty.span)
2587 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2592 "use of SIMD type{} in FFI is highly experimental and \
2593 may result in invalid code",
2597 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2601 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2604 if let hir::FnRetTy::Return(ref ty) = decl.output {
2605 check(ty, fty.output().skip_binder())
2612 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2613 match tcx.hir().get_if_local(def_id) {
2614 Some(Node::ForeignItem(..)) => true,
2616 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2620 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2621 match tcx.hir().get_if_local(def_id) {
2622 Some(Node::Expr(&rustc_hir::Expr {
2623 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2625 })) => tcx.hir().body(body_id).generator_kind(),
2627 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2631 fn from_target_feature(
2634 attr: &ast::Attribute,
2635 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2636 target_features: &mut Vec<Symbol>,
2638 let Some(list) = attr.meta_item_list() else { return };
2639 let bad_item = |span| {
2640 let msg = "malformed `target_feature` attribute input";
2641 let code = "enable = \"..\"".to_owned();
2643 .struct_span_err(span, msg)
2644 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2647 let rust_features = tcx.features();
2649 // Only `enable = ...` is accepted in the meta-item list.
2650 if !item.has_name(sym::enable) {
2651 bad_item(item.span());
2655 // Must be of the form `enable = "..."` (a string).
2656 let Some(value) = item.value_str() else {
2657 bad_item(item.span());
2661 // We allow comma separation to enable multiple features.
2662 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2663 let Some(feature_gate) = supported_target_features.get(feature) else {
2665 format!("the feature named `{}` is not valid for this target", feature);
2666 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2669 format!("`{}` is not valid for this target", feature),
2671 if let Some(stripped) = feature.strip_prefix('+') {
2672 let valid = supported_target_features.contains_key(stripped);
2674 err.help("consider removing the leading `+` in the feature name");
2681 // Only allow features whose feature gates have been enabled.
2682 let allowed = match feature_gate.as_ref().copied() {
2683 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2684 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2685 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2686 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2687 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2688 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2689 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2690 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2691 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2692 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2693 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2694 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2695 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2696 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2697 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2698 Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
2699 Some(name) => bug!("unknown target feature gate {}", name),
2702 if !allowed && id.is_local() {
2704 &tcx.sess.parse_sess,
2705 feature_gate.unwrap(),
2707 &format!("the target feature `{}` is currently unstable", feature),
2711 Some(Symbol::intern(feature))
2716 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2717 use rustc_middle::mir::mono::Linkage::*;
2719 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2720 // applicable to variable declarations and may not really make sense for
2721 // Rust code in the first place but allow them anyway and trust that the
2722 // user knows what they're doing. Who knows, unanticipated use cases may pop
2723 // up in the future.
2725 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2726 // and don't have to be, LLVM treats them as no-ops.
2728 "appending" => Appending,
2729 "available_externally" => AvailableExternally,
2731 "extern_weak" => ExternalWeak,
2732 "external" => External,
2733 "internal" => Internal,
2734 "linkonce" => LinkOnceAny,
2735 "linkonce_odr" => LinkOnceODR,
2736 "private" => Private,
2738 "weak_odr" => WeakODR,
2740 let span = tcx.hir().span_if_local(def_id);
2741 if let Some(span) = span {
2742 tcx.sess.span_fatal(span, "invalid linkage specified")
2744 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2750 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2751 let attrs = tcx.get_attrs(id);
2753 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2754 if tcx.should_inherit_track_caller(id) {
2755 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2758 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2759 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2760 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2761 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2765 // The panic_no_unwind function called by TerminatorKind::Abort will never
2766 // unwind. If the panic handler that it invokes unwind then it will simply
2767 // call the panic handler again.
2768 if Some(id) == tcx.lang_items().panic_no_unwind() {
2769 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2772 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2774 let mut inline_span = None;
2775 let mut link_ordinal_span = None;
2776 let mut no_sanitize_span = None;
2777 for attr in attrs.iter() {
2778 if attr.has_name(sym::cold) {
2779 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2780 } else if attr.has_name(sym::rustc_allocator) {
2781 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2782 } else if attr.has_name(sym::ffi_returns_twice) {
2783 if tcx.is_foreign_item(id) {
2784 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2786 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2791 "`#[ffi_returns_twice]` may only be used on foreign functions"
2795 } else if attr.has_name(sym::ffi_pure) {
2796 if tcx.is_foreign_item(id) {
2797 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2798 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2803 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2807 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2810 // `#[ffi_pure]` is only allowed on foreign functions
2815 "`#[ffi_pure]` may only be used on foreign functions"
2819 } else if attr.has_name(sym::ffi_const) {
2820 if tcx.is_foreign_item(id) {
2821 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2823 // `#[ffi_const]` is only allowed on foreign functions
2828 "`#[ffi_const]` may only be used on foreign functions"
2832 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2833 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2834 } else if attr.has_name(sym::naked) {
2835 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2836 } else if attr.has_name(sym::no_mangle) {
2837 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2838 } else if attr.has_name(sym::no_coverage) {
2839 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2840 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2841 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2842 } else if attr.has_name(sym::used) {
2843 let inner = attr.meta_item_list();
2844 match inner.as_deref() {
2845 Some([item]) if item.has_name(sym::linker) => {
2846 if !tcx.features().used_with_arg {
2848 &tcx.sess.parse_sess,
2851 "`#[used(linker)]` is currently unstable",
2855 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2857 Some([item]) if item.has_name(sym::compiler) => {
2858 if !tcx.features().used_with_arg {
2860 &tcx.sess.parse_sess,
2863 "`#[used(compiler)]` is currently unstable",
2867 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2873 "expected `used`, `used(compiler)` or `used(linker)`",
2877 None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
2879 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2880 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2885 "`#[cmse_nonsecure_entry]` requires C ABI"
2889 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2890 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2893 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2894 } else if attr.has_name(sym::thread_local) {
2895 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2896 } else if attr.has_name(sym::track_caller) {
2897 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2898 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2901 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2903 &tcx.sess.parse_sess,
2904 sym::closure_track_caller,
2906 "`#[track_caller]` on closures is currently unstable",
2910 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2911 } else if attr.has_name(sym::export_name) {
2912 if let Some(s) = attr.value_str() {
2913 if s.as_str().contains('\0') {
2914 // `#[export_name = ...]` will be converted to a null-terminated string,
2915 // so it may not contain any null characters.
2920 "`export_name` may not contain null characters"
2924 codegen_fn_attrs.export_name = Some(s);
2926 } else if attr.has_name(sym::target_feature) {
2927 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2928 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2929 // The `#[target_feature]` attribute is allowed on
2930 // WebAssembly targets on all functions, including safe
2931 // ones. Other targets require that `#[target_feature]` is
2932 // only applied to unsafe functions (pending the
2933 // `target_feature_11` feature) because on most targets
2934 // execution of instructions that are not supported is
2935 // considered undefined behavior. For WebAssembly which is a
2936 // 100% safe target at execution time it's not possible to
2937 // execute undefined instructions, and even if a future
2938 // feature was added in some form for this it would be a
2939 // deterministic trap. There is no undefined behavior when
2940 // executing WebAssembly so `#[target_feature]` is allowed
2941 // on safe functions (but again, only for WebAssembly)
2943 // Note that this is also allowed if `actually_rustdoc` so
2944 // if a target is documenting some wasm-specific code then
2945 // it's not spuriously denied.
2946 } else if !tcx.features().target_feature_11 {
2947 let mut err = feature_err(
2948 &tcx.sess.parse_sess,
2949 sym::target_feature_11,
2951 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2953 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2955 } else if let Some(local_id) = id.as_local() {
2956 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2959 from_target_feature(
2963 supported_target_features,
2964 &mut codegen_fn_attrs.target_features,
2966 } else if attr.has_name(sym::linkage) {
2967 if let Some(val) = attr.value_str() {
2968 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, val.as_str()));
2970 } else if attr.has_name(sym::link_section) {
2971 if let Some(val) = attr.value_str() {
2972 if val.as_str().bytes().any(|b| b == 0) {
2974 "illegal null byte in link_section \
2978 tcx.sess.span_err(attr.span, &msg);
2980 codegen_fn_attrs.link_section = Some(val);
2983 } else if attr.has_name(sym::link_name) {
2984 codegen_fn_attrs.link_name = attr.value_str();
2985 } else if attr.has_name(sym::link_ordinal) {
2986 link_ordinal_span = Some(attr.span);
2987 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2988 codegen_fn_attrs.link_ordinal = ordinal;
2990 } else if attr.has_name(sym::no_sanitize) {
2991 no_sanitize_span = Some(attr.span);
2992 if let Some(list) = attr.meta_item_list() {
2993 for item in list.iter() {
2994 if item.has_name(sym::address) {
2995 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2996 } else if item.has_name(sym::cfi) {
2997 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2998 } else if item.has_name(sym::memory) {
2999 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
3000 } else if item.has_name(sym::memtag) {
3001 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
3002 } else if item.has_name(sym::thread) {
3003 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
3004 } else if item.has_name(sym::hwaddress) {
3005 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
3008 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
3009 .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, or `thread`")
3014 } else if attr.has_name(sym::instruction_set) {
3015 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
3016 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
3017 [NestedMetaItem::MetaItem(set)] => {
3019 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
3020 match segments.as_slice() {
3021 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3022 if !tcx.sess.target.has_thumb_interworking {
3024 tcx.sess.diagnostic(),
3027 "target does not support `#[instruction_set]`"
3031 } else if segments[1] == sym::a32 {
3032 Some(InstructionSetAttr::ArmA32)
3033 } else if segments[1] == sym::t32 {
3034 Some(InstructionSetAttr::ArmT32)
3041 tcx.sess.diagnostic(),
3044 "invalid instruction set specified",
3053 tcx.sess.diagnostic(),
3056 "`#[instruction_set]` requires an argument"
3063 tcx.sess.diagnostic(),
3066 "cannot specify more than one instruction set"
3074 tcx.sess.diagnostic(),
3077 "must specify an instruction set"
3083 } else if attr.has_name(sym::repr) {
3084 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3085 Some(items) => match items.as_slice() {
3086 [item] => match item.name_value_literal() {
3087 Some((sym::align, literal)) => {
3088 let alignment = rustc_attr::parse_alignment(&literal.kind);
3091 Ok(align) => Some(align),
3094 tcx.sess.diagnostic(),
3097 "invalid `repr(align)` attribute: {}",
3116 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3117 if !attr.has_name(sym::inline) {
3120 match attr.meta_kind() {
3121 Some(MetaItemKind::Word) => InlineAttr::Hint,
3122 Some(MetaItemKind::List(ref items)) => {
3123 inline_span = Some(attr.span);
3124 if items.len() != 1 {
3126 tcx.sess.diagnostic(),
3129 "expected one argument"
3133 } else if list_contains_name(&items, sym::always) {
3135 } else if list_contains_name(&items, sym::never) {
3139 tcx.sess.diagnostic(),
3149 Some(MetaItemKind::NameValue(_)) => ia,
3154 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3155 if !attr.has_name(sym::optimize) {
3158 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3159 match attr.meta_kind() {
3160 Some(MetaItemKind::Word) => {
3161 err(attr.span, "expected one argument");
3164 Some(MetaItemKind::List(ref items)) => {
3165 inline_span = Some(attr.span);
3166 if items.len() != 1 {
3167 err(attr.span, "expected one argument");
3169 } else if list_contains_name(&items, sym::size) {
3171 } else if list_contains_name(&items, sym::speed) {
3174 err(items[0].span(), "invalid argument");
3178 Some(MetaItemKind::NameValue(_)) => ia,
3183 // #73631: closures inherit `#[target_feature]` annotations
3184 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3185 let owner_id = tcx.parent(id).expect("closure should have a parent");
3188 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3191 // If a function uses #[target_feature] it can't be inlined into general
3192 // purpose functions as they wouldn't have the right target features
3193 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3195 if !codegen_fn_attrs.target_features.is_empty() {
3196 if codegen_fn_attrs.inline == InlineAttr::Always {
3197 if let Some(span) = inline_span {
3200 "cannot use `#[inline(always)]` with \
3201 `#[target_feature]`",
3207 if !codegen_fn_attrs.no_sanitize.is_empty() {
3208 if codegen_fn_attrs.inline == InlineAttr::Always {
3209 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3210 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3211 tcx.struct_span_lint_hir(
3212 lint::builtin::INLINE_NO_SANITIZE,
3216 lint.build("`no_sanitize` will have no effect after inlining")
3217 .span_note(inline_span, "inlining requested here")
3225 // Weak lang items have the same semantics as "std internal" symbols in the
3226 // sense that they're preserved through all our LTO passes and only
3227 // strippable by the linker.
3229 // Additionally weak lang items have predetermined symbol names.
3230 if tcx.is_weak_lang_item(id) {
3231 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3233 if let Some(name) = weak_lang_items::link_name(attrs) {
3234 codegen_fn_attrs.export_name = Some(name);
3235 codegen_fn_attrs.link_name = Some(name);
3237 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3239 // Internal symbols to the standard library all have no_mangle semantics in
3240 // that they have defined symbol names present in the function name. This
3241 // also applies to weak symbols where they all have known symbol names.
3242 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3243 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3246 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3247 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3248 // intrinsic functions.
3249 if let Some(name) = &codegen_fn_attrs.link_name {
3250 if name.as_str().starts_with("llvm.") {
3251 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3258 /// Computes the set of target features used in a function for the purposes of
3259 /// inline assembly.
3260 fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, id: DefId) -> &'tcx FxHashSet<Symbol> {
3261 let mut target_features = tcx.sess.target_features.clone();
3262 let attrs = tcx.codegen_fn_attrs(id);
3263 target_features.extend(&attrs.target_features);
3264 match attrs.instruction_set {
3266 Some(InstructionSetAttr::ArmA32) => {
3267 target_features.remove(&sym::thumb_mode);
3269 Some(InstructionSetAttr::ArmT32) => {
3270 target_features.insert(sym::thumb_mode);
3273 tcx.arena.alloc(target_features)
3276 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3277 /// applied to the method prototype.
3278 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3279 if let Some(impl_item) = tcx.opt_associated_item(def_id)
3280 && let ty::AssocItemContainer::ImplContainer(_) = impl_item.container
3281 && let Some(trait_item) = impl_item.trait_item_def_id
3284 .codegen_fn_attrs(trait_item)
3286 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3292 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3293 use rustc_ast::{Lit, LitIntType, LitKind};
3294 let meta_item_list = attr.meta_item_list();
3295 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3296 let sole_meta_list = match meta_item_list {
3297 Some([item]) => item.literal(),
3300 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3301 .note("the attribute requires exactly one argument")
3307 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3308 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3309 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3310 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3311 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3313 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3314 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3315 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3316 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3317 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3318 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3319 // about LINK.EXE failing.)
3320 if *ordinal <= u16::MAX as u128 {
3321 Some(*ordinal as u16)
3323 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3325 .struct_span_err(attr.span, &msg)
3326 .note("the value may not exceed `u16::MAX`")
3332 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3333 .note("an unsuffixed integer value, e.g., `1`, is expected")
3339 fn check_link_name_xor_ordinal(
3341 codegen_fn_attrs: &CodegenFnAttrs,
3342 inline_span: Option<Span>,
3344 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3347 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3348 if let Some(span) = inline_span {
3349 tcx.sess.span_err(span, msg);
3355 /// Checks the function annotated with `#[target_feature]` is not a safe
3356 /// trait method implementation, reporting an error if it is.
3357 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3358 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3359 let node = tcx.hir().get(hir_id);
3360 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3361 let parent_id = tcx.hir().get_parent_item(hir_id);
3362 let parent_item = tcx.hir().expect_item(parent_id);
3363 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3367 "`#[target_feature(..)]` cannot be applied to safe trait method",
3369 .span_label(attr_span, "cannot be applied to safe trait method")
3370 .span_label(tcx.def_span(id), "not an `unsafe` function")