1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::AstConv;
18 use crate::bounds::Bounds;
19 use crate::check::intrinsic::intrinsic_operation_unsafety;
20 use crate::constrained_generic_params as cgp;
22 use crate::middle::resolve_lifetime as rl;
24 use rustc_ast::{MetaItemKind, NestedMetaItem};
25 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
26 use rustc_data_structures::captures::Captures;
27 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
28 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
30 use rustc_hir::def::{CtorKind, DefKind};
31 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
32 use rustc_hir::intravisit::{self, Visitor};
33 use rustc_hir::weak_lang_items;
34 use rustc_hir::{GenericParamKind, HirId, Node};
35 use rustc_middle::hir::nested_filter;
36 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
37 use rustc_middle::mir::mono::Linkage;
38 use rustc_middle::ty::query::Providers;
39 use rustc_middle::ty::subst::InternalSubsts;
40 use rustc_middle::ty::util::Discr;
41 use rustc_middle::ty::util::IntTypeExt;
42 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
43 use rustc_middle::ty::{ReprOptions, ToPredicate};
44 use rustc_session::lint;
45 use rustc_session::parse::feature_err;
46 use rustc_span::symbol::{kw, sym, Ident, Symbol};
47 use rustc_span::{Span, DUMMY_SP};
48 use rustc_target::spec::{abi, SanitizerSet};
49 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().deep_visit_item_likes_in_module(module_def_id, &mut CollectItemTypesVisitor { tcx });
65 pub fn provide(providers: &mut Providers) {
66 *providers = Providers {
67 opt_const_param_of: type_of::opt_const_param_of,
68 type_of: type_of::type_of,
69 item_bounds: item_bounds::item_bounds,
70 explicit_item_bounds: item_bounds::explicit_item_bounds,
73 predicates_defined_on,
74 explicit_predicates_of,
76 super_predicates_that_define_assoc_type,
77 trait_explicit_predicates_and_bounds,
78 type_param_predicates,
88 collect_mod_item_types,
89 should_inherit_track_caller,
94 ///////////////////////////////////////////////////////////////////////////
96 /// Context specific to some particular item. This is what implements
97 /// `AstConv`. It has information about the predicates that are defined
98 /// on the trait. Unfortunately, this predicate information is
99 /// available in various different forms at various points in the
100 /// process. So we can't just store a pointer to e.g., the AST or the
101 /// parsed ty form, we have to be more flexible. To this end, the
102 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
103 /// `get_type_parameter_bounds` requests, drawing the information from
104 /// the AST (`hir::Generics`), recursively.
105 pub struct ItemCtxt<'tcx> {
110 ///////////////////////////////////////////////////////////////////////////
113 crate struct HirPlaceholderCollector(crate Vec<Span>);
115 impl<'v> Visitor<'v> for HirPlaceholderCollector {
116 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
117 if let hir::TyKind::Infer = t.kind {
120 intravisit::walk_ty(self, t)
122 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
124 hir::GenericArg::Infer(inf) => {
125 self.0.push(inf.span);
126 intravisit::walk_inf(self, inf);
128 hir::GenericArg::Type(t) => self.visit_ty(t),
132 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
133 if let &hir::ArrayLen::Infer(_, span) = length {
136 intravisit::walk_array_len(self, length)
140 struct CollectItemTypesVisitor<'tcx> {
144 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
145 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
146 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
147 crate fn placeholder_type_error<'tcx>(
149 generics: Option<&hir::Generics<'_>>,
150 placeholder_types: Vec<Span>,
152 hir_ty: Option<&hir::Ty<'_>>,
155 if placeholder_types.is_empty() {
159 placeholder_type_error_diag(tcx, generics, placeholder_types, vec![], suggest, hir_ty, kind)
163 crate fn placeholder_type_error_diag<'tcx>(
165 generics: Option<&hir::Generics<'_>>,
166 placeholder_types: Vec<Span>,
167 additional_spans: Vec<Span>,
169 hir_ty: Option<&hir::Ty<'_>>,
171 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
172 if placeholder_types.is_empty() {
173 return bad_placeholder(tcx, additional_spans, kind);
176 let params = generics.map(|g| g.params).unwrap_or_default();
177 let type_name = params.next_type_param_name(None);
178 let mut sugg: Vec<_> =
179 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
181 if let Some(generics) = generics {
182 if let Some(arg) = params.iter().find(|arg| {
183 matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. }))
185 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
186 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
187 sugg.push((arg.span, (*type_name).to_string()));
188 } else if let Some(span) = generics.span_for_param_suggestion() {
189 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
190 sugg.push((span, format!(", {}", type_name)));
192 sugg.push((generics.span, format!("<{}>", type_name)));
197 bad_placeholder(tcx, placeholder_types.into_iter().chain(additional_spans).collect(), kind);
199 // Suggest, but only if it is not a function in const or static
201 let mut is_fn = false;
202 let mut is_const_or_static = false;
204 if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind {
207 // Check if parent is const or static
208 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
209 let parent_node = tcx.hir().get(parent_id);
211 is_const_or_static = matches!(
213 Node::Item(&hir::Item {
214 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
216 }) | Node::TraitItem(&hir::TraitItem {
217 kind: hir::TraitItemKind::Const(..),
219 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
223 // if function is wrapped around a const or static,
224 // then don't show the suggestion
225 if !(is_fn && is_const_or_static) {
226 err.multipart_suggestion(
227 "use type parameters instead",
229 Applicability::HasPlaceholders,
237 fn reject_placeholder_type_signatures_in_item<'tcx>(
239 item: &'tcx hir::Item<'tcx>,
241 let (generics, suggest) = match &item.kind {
242 hir::ItemKind::Union(_, generics)
243 | hir::ItemKind::Enum(_, generics)
244 | hir::ItemKind::TraitAlias(generics, _)
245 | hir::ItemKind::Trait(_, _, generics, ..)
246 | hir::ItemKind::Impl(hir::Impl { generics, .. })
247 | hir::ItemKind::Struct(_, generics) => (generics, true),
248 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
249 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
250 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
254 let mut visitor = HirPlaceholderCollector::default();
255 visitor.visit_item(item);
257 placeholder_type_error(tcx, Some(generics), visitor.0, suggest, None, item.kind.descr());
260 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
261 type NestedFilter = nested_filter::OnlyBodies;
263 fn nested_visit_map(&mut self) -> Self::Map {
267 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
268 convert_item(self.tcx, item.item_id());
269 reject_placeholder_type_signatures_in_item(self.tcx, item);
270 intravisit::walk_item(self, item);
273 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
274 for param in generics.params {
276 hir::GenericParamKind::Lifetime { .. } => {}
277 hir::GenericParamKind::Type { default: Some(_), .. } => {
278 let def_id = self.tcx.hir().local_def_id(param.hir_id);
279 self.tcx.ensure().type_of(def_id);
281 hir::GenericParamKind::Type { .. } => {}
282 hir::GenericParamKind::Const { default, .. } => {
283 let def_id = self.tcx.hir().local_def_id(param.hir_id);
284 self.tcx.ensure().type_of(def_id);
285 if let Some(default) = default {
286 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
287 // need to store default and type of default
288 self.tcx.ensure().type_of(default_def_id);
289 self.tcx.ensure().const_param_default(def_id);
294 intravisit::walk_generics(self, generics);
297 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
298 if let hir::ExprKind::Closure(..) = expr.kind {
299 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
300 self.tcx.ensure().generics_of(def_id);
301 // We do not call `type_of` for closures here as that
302 // depends on typecheck and would therefore hide
303 // any further errors in case one typeck fails.
305 intravisit::walk_expr(self, expr);
308 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
309 convert_trait_item(self.tcx, trait_item.trait_item_id());
310 intravisit::walk_trait_item(self, trait_item);
313 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
314 convert_impl_item(self.tcx, impl_item.impl_item_id());
315 intravisit::walk_impl_item(self, impl_item);
319 ///////////////////////////////////////////////////////////////////////////
320 // Utility types and common code for the above passes.
322 fn bad_placeholder<'tcx>(
324 mut spans: Vec<Span>,
326 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
327 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
330 let mut err = struct_span_err!(
334 "the placeholder `_` is not allowed within types on item signatures for {}",
338 err.span_label(span, "not allowed in type signatures");
343 impl<'tcx> ItemCtxt<'tcx> {
344 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
345 ItemCtxt { tcx, item_def_id }
348 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
349 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
352 pub fn hir_id(&self) -> hir::HirId {
353 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
356 pub fn node(&self) -> hir::Node<'tcx> {
357 self.tcx.hir().get(self.hir_id())
361 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
362 fn tcx(&self) -> TyCtxt<'tcx> {
366 fn item_def_id(&self) -> Option<DefId> {
367 Some(self.item_def_id)
370 fn get_type_parameter_bounds(
375 ) -> ty::GenericPredicates<'tcx> {
376 self.tcx.at(span).type_param_predicates((
378 def_id.expect_local(),
383 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
387 fn allow_ty_infer(&self) -> bool {
391 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
392 self.tcx().ty_error_with_message(span, "bad placeholder type")
395 fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
396 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match *r {
397 ty::ReErased => self.tcx.lifetimes.re_static,
400 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
403 fn projected_ty_from_poly_trait_ref(
407 item_segment: &hir::PathSegment<'_>,
408 poly_trait_ref: ty::PolyTraitRef<'tcx>,
410 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
411 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
419 self.tcx().mk_projection(item_def_id, item_substs)
421 // There are no late-bound regions; we can just ignore the binder.
422 let mut err = struct_span_err!(
426 "cannot use the associated type of a trait \
427 with uninferred generic parameters"
431 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
433 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
435 hir::ItemKind::Enum(_, generics)
436 | hir::ItemKind::Struct(_, generics)
437 | hir::ItemKind::Union(_, generics) => {
438 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
439 let (lt_sp, sugg) = match generics.params {
440 [] => (generics.span, format!("<{}>", lt_name)),
442 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
445 let suggestions = vec![
448 span.with_hi(item_segment.ident.span.lo()),
451 // Replace the existing lifetimes with a new named lifetime.
453 .replace_late_bound_regions(poly_trait_ref, |_| {
454 self.tcx.mk_region(ty::ReEarlyBound(
455 ty::EarlyBoundRegion {
458 name: Symbol::intern(<_name),
466 err.multipart_suggestion(
467 "use a fully qualified path with explicit lifetimes",
469 Applicability::MaybeIncorrect,
475 hir::Node::Item(hir::Item {
477 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
481 | hir::Node::ForeignItem(_)
482 | hir::Node::TraitItem(_)
483 | hir::Node::ImplItem(_) => {
484 err.span_suggestion_verbose(
485 span.with_hi(item_segment.ident.span.lo()),
486 "use a fully qualified path with inferred lifetimes",
489 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
490 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
492 Applicability::MaybeIncorrect,
498 self.tcx().ty_error()
502 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
503 // Types in item signatures are not normalized to avoid undue dependencies.
507 fn set_tainted_by_errors(&self) {
508 // There's no obvious place to track this, so just let it go.
511 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
512 // There's no place to record types from signatures?
516 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
517 fn get_new_lifetime_name<'tcx>(
519 poly_trait_ref: ty::PolyTraitRef<'tcx>,
520 generics: &hir::Generics<'tcx>,
522 let existing_lifetimes = tcx
523 .collect_referenced_late_bound_regions(&poly_trait_ref)
526 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
527 Some(name.as_str().to_string())
532 .chain(generics.params.iter().filter_map(|param| {
533 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
534 Some(param.name.ident().as_str().to_string())
539 .collect::<FxHashSet<String>>();
541 let a_to_z_repeat_n = |n| {
542 (b'a'..=b'z').map(move |c| {
543 let mut s = '\''.to_string();
544 s.extend(std::iter::repeat(char::from(c)).take(n));
549 // If all single char lifetime names are present, we wrap around and double the chars.
550 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
553 /// Returns the predicates defined on `item_def_id` of the form
554 /// `X: Foo` where `X` is the type parameter `def_id`.
555 fn type_param_predicates(
557 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
558 ) -> ty::GenericPredicates<'_> {
561 // In the AST, bounds can derive from two places. Either
562 // written inline like `<T: Foo>` or in a where-clause like
565 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
566 let param_owner = tcx.hir().ty_param_owner(def_id);
567 let generics = tcx.generics_of(param_owner);
568 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
569 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
571 // Don't look for bounds where the type parameter isn't in scope.
572 let parent = if item_def_id == param_owner.to_def_id() {
575 tcx.generics_of(item_def_id).parent
578 let mut result = parent
580 let icx = ItemCtxt::new(tcx, parent);
581 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
583 .unwrap_or_default();
584 let mut extend = None;
586 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
587 let ast_generics = match tcx.hir().get(item_hir_id) {
588 Node::TraitItem(item) => &item.generics,
590 Node::ImplItem(item) => &item.generics,
592 Node::Item(item) => {
594 ItemKind::Fn(.., ref generics, _)
595 | ItemKind::Impl(hir::Impl { ref generics, .. })
596 | ItemKind::TyAlias(_, ref generics)
597 | ItemKind::OpaqueTy(OpaqueTy {
599 origin: hir::OpaqueTyOrigin::TyAlias,
602 | ItemKind::Enum(_, ref generics)
603 | ItemKind::Struct(_, ref generics)
604 | ItemKind::Union(_, ref generics) => generics,
605 ItemKind::Trait(_, _, ref generics, ..) => {
606 // Implied `Self: Trait` and supertrait bounds.
607 if param_id == item_hir_id {
608 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
610 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
618 Node::ForeignItem(item) => match item.kind {
619 ForeignItemKind::Fn(_, _, ref generics) => generics,
626 let icx = ItemCtxt::new(tcx, item_def_id);
627 let extra_predicates = extend.into_iter().chain(
628 icx.type_parameter_bounds_in_generics(
632 OnlySelfBounds(true),
636 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
637 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
642 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
646 impl<'tcx> ItemCtxt<'tcx> {
647 /// Finds bounds from `hir::Generics`. This requires scanning through the
648 /// AST. We do this to avoid having to convert *all* the bounds, which
649 /// would create artificial cycles. Instead, we can only convert the
650 /// bounds for a type parameter `X` if `X::Foo` is used.
651 #[instrument(level = "trace", skip(self, ast_generics))]
652 fn type_parameter_bounds_in_generics(
654 ast_generics: &'tcx hir::Generics<'tcx>,
655 param_id: hir::HirId,
657 only_self_bounds: OnlySelfBounds,
658 assoc_name: Option<Ident>,
659 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
660 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
661 debug!(?param_def_id);
665 .filter_map(|wp| match *wp {
666 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
670 let bt = if bp.is_param_bound(param_def_id) {
672 } else if !only_self_bounds.0 {
673 Some(self.to_ty(bp.bounded_ty))
677 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
679 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b, bvars))).filter(
680 |(_, b, _)| match assoc_name {
681 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
686 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars))
690 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
691 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
694 hir::GenericBound::Trait(poly_trait_ref, _) => {
695 let trait_ref = &poly_trait_ref.trait_ref;
696 if let Some(trait_did) = trait_ref.trait_def_id() {
697 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
707 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
708 let it = tcx.hir().item(item_id);
709 debug!("convert: item {} with id {}", it.ident, it.hir_id());
710 let def_id = item_id.def_id;
713 // These don't define types.
714 hir::ItemKind::ExternCrate(_)
715 | hir::ItemKind::Use(..)
716 | hir::ItemKind::Macro(..)
717 | hir::ItemKind::Mod(_)
718 | hir::ItemKind::GlobalAsm(_) => {}
719 hir::ItemKind::ForeignMod { items, .. } => {
721 let item = tcx.hir().foreign_item(item.id);
722 tcx.ensure().generics_of(item.def_id);
723 tcx.ensure().type_of(item.def_id);
724 tcx.ensure().predicates_of(item.def_id);
726 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
727 hir::ForeignItemKind::Static(..) => {
728 let mut visitor = HirPlaceholderCollector::default();
729 visitor.visit_foreign_item(item);
730 placeholder_type_error(
743 hir::ItemKind::Enum(ref enum_definition, _) => {
744 tcx.ensure().generics_of(def_id);
745 tcx.ensure().type_of(def_id);
746 tcx.ensure().predicates_of(def_id);
747 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
749 hir::ItemKind::Impl { .. } => {
750 tcx.ensure().generics_of(def_id);
751 tcx.ensure().type_of(def_id);
752 tcx.ensure().impl_trait_ref(def_id);
753 tcx.ensure().predicates_of(def_id);
755 hir::ItemKind::Trait(..) => {
756 tcx.ensure().generics_of(def_id);
757 tcx.ensure().trait_def(def_id);
758 tcx.at(it.span).super_predicates_of(def_id);
759 tcx.ensure().predicates_of(def_id);
761 hir::ItemKind::TraitAlias(..) => {
762 tcx.ensure().generics_of(def_id);
763 tcx.at(it.span).super_predicates_of(def_id);
764 tcx.ensure().predicates_of(def_id);
766 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
767 tcx.ensure().generics_of(def_id);
768 tcx.ensure().type_of(def_id);
769 tcx.ensure().predicates_of(def_id);
771 for f in struct_def.fields() {
772 let def_id = tcx.hir().local_def_id(f.hir_id);
773 tcx.ensure().generics_of(def_id);
774 tcx.ensure().type_of(def_id);
775 tcx.ensure().predicates_of(def_id);
778 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
779 convert_variant_ctor(tcx, ctor_hir_id);
783 // Desugared from `impl Trait`, so visited by the function's return type.
784 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
785 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
789 // Don't call `type_of` on opaque types, since that depends on type
790 // checking function bodies. `check_item_type` ensures that it's called
792 hir::ItemKind::OpaqueTy(..) => {
793 tcx.ensure().generics_of(def_id);
794 tcx.ensure().predicates_of(def_id);
795 tcx.ensure().explicit_item_bounds(def_id);
797 hir::ItemKind::TyAlias(..)
798 | hir::ItemKind::Static(..)
799 | hir::ItemKind::Const(..)
800 | hir::ItemKind::Fn(..) => {
801 tcx.ensure().generics_of(def_id);
802 tcx.ensure().type_of(def_id);
803 tcx.ensure().predicates_of(def_id);
805 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
806 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
807 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
808 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
809 if let hir::TyKind::TraitObject(..) = ty.kind {
810 let mut visitor = HirPlaceholderCollector::default();
811 visitor.visit_item(it);
812 placeholder_type_error(tcx, None, visitor.0, false, None, it.kind.descr());
821 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
822 let trait_item = tcx.hir().trait_item(trait_item_id);
823 tcx.ensure().generics_of(trait_item_id.def_id);
825 match trait_item.kind {
826 hir::TraitItemKind::Fn(..) => {
827 tcx.ensure().type_of(trait_item_id.def_id);
828 tcx.ensure().fn_sig(trait_item_id.def_id);
831 hir::TraitItemKind::Const(.., Some(_)) => {
832 tcx.ensure().type_of(trait_item_id.def_id);
835 hir::TraitItemKind::Const(..) => {
836 tcx.ensure().type_of(trait_item_id.def_id);
837 // Account for `const C: _;`.
838 let mut visitor = HirPlaceholderCollector::default();
839 visitor.visit_trait_item(trait_item);
840 placeholder_type_error(tcx, None, visitor.0, false, None, "constant");
843 hir::TraitItemKind::Type(_, Some(_)) => {
844 tcx.ensure().item_bounds(trait_item_id.def_id);
845 tcx.ensure().type_of(trait_item_id.def_id);
846 // Account for `type T = _;`.
847 let mut visitor = HirPlaceholderCollector::default();
848 visitor.visit_trait_item(trait_item);
849 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
852 hir::TraitItemKind::Type(_, None) => {
853 tcx.ensure().item_bounds(trait_item_id.def_id);
854 // #74612: Visit and try to find bad placeholders
855 // even if there is no concrete type.
856 let mut visitor = HirPlaceholderCollector::default();
857 visitor.visit_trait_item(trait_item);
859 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
863 tcx.ensure().predicates_of(trait_item_id.def_id);
866 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
867 let def_id = impl_item_id.def_id;
868 tcx.ensure().generics_of(def_id);
869 tcx.ensure().type_of(def_id);
870 tcx.ensure().predicates_of(def_id);
871 let impl_item = tcx.hir().impl_item(impl_item_id);
872 match impl_item.kind {
873 hir::ImplItemKind::Fn(..) => {
874 tcx.ensure().fn_sig(def_id);
876 hir::ImplItemKind::TyAlias(_) => {
877 // Account for `type T = _;`
878 let mut visitor = HirPlaceholderCollector::default();
879 visitor.visit_impl_item(impl_item);
881 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
883 hir::ImplItemKind::Const(..) => {}
887 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
888 let def_id = tcx.hir().local_def_id(ctor_id);
889 tcx.ensure().generics_of(def_id);
890 tcx.ensure().type_of(def_id);
891 tcx.ensure().predicates_of(def_id);
894 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
895 let def = tcx.adt_def(def_id);
896 let repr_type = def.repr().discr_type();
897 let initial = repr_type.initial_discriminant(tcx);
898 let mut prev_discr = None::<Discr<'_>>;
900 // fill the discriminant values and field types
901 for variant in variants {
902 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
904 if let Some(ref e) = variant.disr_expr {
905 let expr_did = tcx.hir().local_def_id(e.hir_id);
906 def.eval_explicit_discr(tcx, expr_did.to_def_id())
907 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
910 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
913 format!("overflowed on value after {}", prev_discr.unwrap()),
916 "explicitly set `{} = {}` if that is desired outcome",
917 variant.ident, wrapped_discr
922 .unwrap_or(wrapped_discr),
925 for f in variant.data.fields() {
926 let def_id = tcx.hir().local_def_id(f.hir_id);
927 tcx.ensure().generics_of(def_id);
928 tcx.ensure().type_of(def_id);
929 tcx.ensure().predicates_of(def_id);
932 // Convert the ctor, if any. This also registers the variant as
934 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
935 convert_variant_ctor(tcx, ctor_hir_id);
942 variant_did: Option<LocalDefId>,
943 ctor_did: Option<LocalDefId>,
945 discr: ty::VariantDiscr,
946 def: &hir::VariantData<'_>,
947 adt_kind: ty::AdtKind,
948 parent_did: LocalDefId,
949 ) -> ty::VariantDef {
950 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
955 let fid = tcx.hir().local_def_id(f.hir_id);
956 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
957 if let Some(prev_span) = dup_span {
958 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
964 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
967 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
970 let recovered = match def {
971 hir::VariantData::Struct(_, r) => *r,
976 variant_did.map(LocalDefId::to_def_id),
977 ctor_did.map(LocalDefId::to_def_id),
980 CtorKind::from_hir(def),
982 parent_did.to_def_id(),
984 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
985 || variant_did.map_or(false, |variant_did| {
986 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
991 fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
994 let def_id = def_id.expect_local();
995 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
996 let Node::Item(item) = tcx.hir().get(hir_id) else {
1000 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1001 let (kind, variants) = match item.kind {
1002 ItemKind::Enum(ref def, _) => {
1003 let mut distance_from_explicit = 0;
1008 let variant_did = Some(tcx.hir().local_def_id(v.id));
1010 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1012 let discr = if let Some(ref e) = v.disr_expr {
1013 distance_from_explicit = 0;
1014 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1016 ty::VariantDiscr::Relative(distance_from_explicit)
1018 distance_from_explicit += 1;
1033 (AdtKind::Enum, variants)
1035 ItemKind::Struct(ref def, _) => {
1036 let variant_did = None::<LocalDefId>;
1037 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1039 let variants = std::iter::once(convert_variant(
1044 ty::VariantDiscr::Relative(0),
1051 (AdtKind::Struct, variants)
1053 ItemKind::Union(ref def, _) => {
1054 let variant_did = None;
1055 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1057 let variants = std::iter::once(convert_variant(
1062 ty::VariantDiscr::Relative(0),
1069 (AdtKind::Union, variants)
1073 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1076 /// Ensures that the super-predicates of the trait with a `DefId`
1077 /// of `trait_def_id` are converted and stored. This also ensures that
1078 /// the transitive super-predicates are converted.
1079 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1080 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1081 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1084 /// Ensures that the super-predicates of the trait with a `DefId`
1085 /// of `trait_def_id` are converted and stored. This also ensures that
1086 /// the transitive super-predicates are converted.
1087 fn super_predicates_that_define_assoc_type(
1089 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1090 ) -> ty::GenericPredicates<'_> {
1092 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1093 trait_def_id, assoc_name
1095 if trait_def_id.is_local() {
1096 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1097 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1099 let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
1100 bug!("trait_node_id {} is not an item", trait_hir_id);
1103 let (generics, bounds) = match item.kind {
1104 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1105 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1106 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1109 let icx = ItemCtxt::new(tcx, trait_def_id);
1111 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1112 let self_param_ty = tcx.types.self_param;
1113 let superbounds1 = if let Some(assoc_name) = assoc_name {
1114 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1121 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1124 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1126 // Convert any explicit superbounds in the where-clause,
1127 // e.g., `trait Foo where Self: Bar`.
1128 // In the case of trait aliases, however, we include all bounds in the where-clause,
1129 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1130 // as one of its "superpredicates".
1131 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1132 let superbounds2 = icx.type_parameter_bounds_in_generics(
1136 OnlySelfBounds(!is_trait_alias),
1140 // Combine the two lists to form the complete set of superbounds:
1141 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1142 debug!(?superbounds);
1144 // Now require that immediate supertraits are converted,
1145 // which will, in turn, reach indirect supertraits.
1146 if assoc_name.is_none() {
1147 // Now require that immediate supertraits are converted,
1148 // which will, in turn, reach indirect supertraits.
1149 for &(pred, span) in superbounds {
1150 debug!("superbound: {:?}", pred);
1151 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1152 tcx.at(span).super_predicates_of(bound.def_id());
1157 ty::GenericPredicates { parent: None, predicates: superbounds }
1159 // if `assoc_name` is None, then the query should've been redirected to an
1160 // external provider
1161 assert!(assoc_name.is_some());
1162 tcx.super_predicates_of(trait_def_id)
1166 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1167 let item = tcx.hir().expect_item(def_id.expect_local());
1169 let (is_auto, unsafety, items) = match item.kind {
1170 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1171 (is_auto == hir::IsAuto::Yes, unsafety, items)
1173 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1174 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1177 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1178 if paren_sugar && !tcx.features().unboxed_closures {
1182 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1183 which traits can use parenthetical notation",
1185 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1189 let is_marker = tcx.has_attr(def_id, sym::marker);
1190 let skip_array_during_method_dispatch =
1191 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1192 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1193 ty::trait_def::TraitSpecializationKind::Marker
1194 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1195 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1197 ty::trait_def::TraitSpecializationKind::None
1199 let must_implement_one_of = tcx
1200 .get_attr(def_id, sym::rustc_must_implement_one_of)
1201 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1202 // and that they are all identifiers
1203 .and_then(|attr| match attr.meta_item_list() {
1204 Some(items) if items.len() < 2 => {
1208 "the `#[rustc_must_implement_one_of]` attribute must be \
1209 used with at least 2 args",
1215 Some(items) => items
1217 .map(|item| item.ident().ok_or(item.span()))
1218 .collect::<Result<Box<[_]>, _>>()
1221 .struct_span_err(span, "must be a name of an associated function")
1225 .zip(Some(attr.span)),
1226 // Error is reported by `rustc_attr!`
1229 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1230 // functions in the trait with default implementations
1231 .and_then(|(list, attr_span)| {
1232 let errors = list.iter().filter_map(|ident| {
1233 let item = items.iter().find(|item| item.ident == *ident);
1236 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1237 if !item.defaultness.has_value() {
1241 "This function doesn't have a default implementation",
1243 .span_note(attr_span, "required by this annotation")
1253 .struct_span_err(item.span, "Not a function")
1254 .span_note(attr_span, "required by this annotation")
1256 "All `#[rustc_must_implement_one_of]` arguments \
1257 must be associated function names",
1263 .struct_span_err(ident.span, "Function not found in this trait")
1271 (errors.count() == 0).then_some(list)
1273 // Check for duplicates
1275 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1276 let mut no_dups = true;
1278 for ident in &*list {
1279 if let Some(dup) = set.insert(ident.name, ident.span) {
1281 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1283 "All `#[rustc_must_implement_one_of]` arguments \
1292 no_dups.then_some(list)
1301 skip_array_during_method_dispatch,
1303 must_implement_one_of,
1307 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1308 struct LateBoundRegionsDetector<'tcx> {
1310 outer_index: ty::DebruijnIndex,
1311 has_late_bound_regions: Option<Span>,
1314 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1315 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1316 if self.has_late_bound_regions.is_some() {
1320 hir::TyKind::BareFn(..) => {
1321 self.outer_index.shift_in(1);
1322 intravisit::walk_ty(self, ty);
1323 self.outer_index.shift_out(1);
1325 _ => intravisit::walk_ty(self, ty),
1329 fn visit_poly_trait_ref(
1331 tr: &'tcx hir::PolyTraitRef<'tcx>,
1332 m: hir::TraitBoundModifier,
1334 if self.has_late_bound_regions.is_some() {
1337 self.outer_index.shift_in(1);
1338 intravisit::walk_poly_trait_ref(self, tr, m);
1339 self.outer_index.shift_out(1);
1342 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1343 if self.has_late_bound_regions.is_some() {
1347 match self.tcx.named_region(lt.hir_id) {
1348 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1350 rl::Region::LateBound(debruijn, _, _)
1351 | rl::Region::LateBoundAnon(debruijn, _, _),
1352 ) if debruijn < self.outer_index => {}
1354 rl::Region::LateBound(..)
1355 | rl::Region::LateBoundAnon(..)
1356 | rl::Region::Free(..),
1359 self.has_late_bound_regions = Some(lt.span);
1365 fn has_late_bound_regions<'tcx>(
1368 generics: &'tcx hir::Generics<'tcx>,
1369 decl: &'tcx hir::FnDecl<'tcx>,
1371 let mut visitor = LateBoundRegionsDetector {
1373 outer_index: ty::INNERMOST,
1374 has_late_bound_regions: None,
1376 let late_bound_map = tcx.is_late_bound_map(def_id);
1377 let is_late_bound = |id| {
1378 let id = tcx.hir().local_def_id(id);
1379 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
1381 for param in generics.params {
1382 if let GenericParamKind::Lifetime { .. } = param.kind {
1383 if is_late_bound(param.hir_id) {
1384 return Some(param.span);
1388 visitor.visit_fn_decl(decl);
1389 visitor.has_late_bound_regions
1393 Node::TraitItem(item) => match item.kind {
1394 hir::TraitItemKind::Fn(ref sig, _) => {
1395 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1399 Node::ImplItem(item) => match item.kind {
1400 hir::ImplItemKind::Fn(ref sig, _) => {
1401 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1405 Node::ForeignItem(item) => match item.kind {
1406 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1407 has_late_bound_regions(tcx, item.def_id, generics, fn_decl)
1411 Node::Item(item) => match item.kind {
1412 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1413 has_late_bound_regions(tcx, item.def_id, generics, sig.decl)
1421 struct AnonConstInParamTyDetector {
1423 found_anon_const_in_param_ty: bool,
1427 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1428 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1429 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1430 let prev = self.in_param_ty;
1431 self.in_param_ty = true;
1433 self.in_param_ty = prev;
1437 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1438 if self.in_param_ty && self.ct == c.hir_id {
1439 self.found_anon_const_in_param_ty = true;
1441 intravisit::walk_anon_const(self, c)
1446 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1449 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1451 let node = tcx.hir().get(hir_id);
1452 let parent_def_id = match node {
1454 | Node::TraitItem(_)
1457 | Node::Field(_) => {
1458 let parent_id = tcx.hir().get_parent_item(hir_id);
1459 Some(parent_id.to_def_id())
1461 // FIXME(#43408) always enable this once `lazy_normalization` is
1462 // stable enough and does not need a feature gate anymore.
1463 Node::AnonConst(_) => {
1464 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1466 let mut in_param_ty = false;
1467 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1468 if let Some(generics) = node.generics() {
1469 let mut visitor = AnonConstInParamTyDetector {
1471 found_anon_const_in_param_ty: false,
1475 visitor.visit_generics(generics);
1476 in_param_ty = visitor.found_anon_const_in_param_ty;
1482 // We do not allow generic parameters in anon consts if we are inside
1483 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1485 } else if tcx.lazy_normalization() {
1486 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1487 // If the def_id we are calling generics_of on is an anon ct default i.e:
1489 // struct Foo<const N: usize = { .. }>;
1490 // ^^^ ^ ^^^^^^ def id of this anon const
1494 // then we only want to return generics for params to the left of `N`. If we don't do that we
1495 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1497 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1498 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1499 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1501 // We fix this by having this function return the parent's generics ourselves and truncating the
1502 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1504 // For the above code example that means we want `substs: []`
1505 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1506 // the def id of the `{ N + 1 }` anon const
1507 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1509 // This has some implications for how we get the predicates available to the anon const
1510 // see `explicit_predicates_of` for more information on this
1511 let generics = tcx.generics_of(parent_def_id.to_def_id());
1512 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1513 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1514 // In the above example this would be .params[..N#0]
1515 let params = generics.params[..param_def_idx as usize].to_owned();
1516 let param_def_id_to_index =
1517 params.iter().map(|param| (param.def_id, param.index)).collect();
1519 return ty::Generics {
1520 // we set the parent of these generics to be our parent's parent so that we
1521 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1522 // struct Foo<const N: usize, const M: usize = { ... }>;
1523 parent: generics.parent,
1524 parent_count: generics.parent_count,
1526 param_def_id_to_index,
1527 has_self: generics.has_self,
1528 has_late_bound_regions: generics.has_late_bound_regions,
1532 // HACK(eddyb) this provides the correct generics when
1533 // `feature(generic_const_expressions)` is enabled, so that const expressions
1534 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1536 // Note that we do not supply the parent generics when using
1537 // `min_const_generics`.
1538 Some(parent_def_id.to_def_id())
1540 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1542 // HACK(eddyb) this provides the correct generics for repeat
1543 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1544 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1545 // as they shouldn't be able to cause query cycle errors.
1546 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1547 if constant.hir_id() == hir_id =>
1549 Some(parent_def_id.to_def_id())
1551 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1552 if constant.hir_id == hir_id =>
1554 Some(parent_def_id.to_def_id())
1556 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1557 Some(tcx.typeck_root_def_id(def_id))
1559 // Exclude `GlobalAsm` here which cannot have generics.
1560 Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
1561 if asm.operands.iter().any(|(op, _op_sp)| match op {
1562 hir::InlineAsmOperand::Const { anon_const }
1563 | hir::InlineAsmOperand::SymFn { anon_const } => {
1564 anon_const.hir_id == hir_id
1569 Some(parent_def_id.to_def_id())
1575 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1576 Some(tcx.typeck_root_def_id(def_id))
1578 Node::Item(item) => match item.kind {
1579 ItemKind::OpaqueTy(hir::OpaqueTy {
1581 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1583 }) => Some(fn_def_id.to_def_id()),
1584 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1585 let parent_id = tcx.hir().get_parent_item(hir_id);
1586 assert_ne!(parent_id, CRATE_DEF_ID);
1587 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1588 // Opaque types are always nested within another item, and
1589 // inherit the generics of the item.
1590 Some(parent_id.to_def_id())
1597 let mut opt_self = None;
1598 let mut allow_defaults = false;
1600 let no_generics = hir::Generics::empty();
1601 let ast_generics = match node {
1602 Node::TraitItem(item) => &item.generics,
1604 Node::ImplItem(item) => &item.generics,
1606 Node::Item(item) => {
1608 ItemKind::Fn(.., ref generics, _)
1609 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1611 ItemKind::TyAlias(_, ref generics)
1612 | ItemKind::Enum(_, ref generics)
1613 | ItemKind::Struct(_, ref generics)
1614 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1615 | ItemKind::Union(_, ref generics) => {
1616 allow_defaults = true;
1620 ItemKind::Trait(_, _, ref generics, ..)
1621 | ItemKind::TraitAlias(ref generics, ..) => {
1622 // Add in the self type parameter.
1624 // Something of a hack: use the node id for the trait, also as
1625 // the node id for the Self type parameter.
1626 let param_id = item.def_id;
1628 opt_self = Some(ty::GenericParamDef {
1630 name: kw::SelfUpper,
1631 def_id: param_id.to_def_id(),
1632 pure_wrt_drop: false,
1633 kind: ty::GenericParamDefKind::Type {
1635 object_lifetime_default: rl::Set1::Empty,
1640 allow_defaults = true;
1648 Node::ForeignItem(item) => match item.kind {
1649 ForeignItemKind::Static(..) => &no_generics,
1650 ForeignItemKind::Fn(_, _, ref generics) => generics,
1651 ForeignItemKind::Type => &no_generics,
1657 let has_self = opt_self.is_some();
1658 let mut parent_has_self = false;
1659 let mut own_start = has_self as u32;
1660 let parent_count = parent_def_id.map_or(0, |def_id| {
1661 let generics = tcx.generics_of(def_id);
1663 parent_has_self = generics.has_self;
1664 own_start = generics.count() as u32;
1665 generics.parent_count + generics.params.len()
1668 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1670 if let Some(opt_self) = opt_self {
1671 params.push(opt_self);
1674 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics);
1675 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1676 name: param.name.ident().name,
1677 index: own_start + i as u32,
1678 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1679 pure_wrt_drop: param.pure_wrt_drop,
1680 kind: ty::GenericParamDefKind::Lifetime,
1683 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id.owner);
1685 // Now create the real type and const parameters.
1686 let type_start = own_start - has_self as u32 + params.len() as u32;
1689 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1690 GenericParamKind::Lifetime { .. } => None,
1691 GenericParamKind::Type { ref default, synthetic, .. } => {
1692 if !allow_defaults && default.is_some() {
1693 if !tcx.features().default_type_parameter_fallback {
1694 tcx.struct_span_lint_hir(
1695 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1700 "defaults for type parameters are only allowed in \
1701 `struct`, `enum`, `type`, or `trait` definitions",
1709 let kind = ty::GenericParamDefKind::Type {
1710 has_default: default.is_some(),
1711 object_lifetime_default: object_lifetime_defaults
1713 .map_or(rl::Set1::Empty, |o| o[i]),
1717 let param_def = ty::GenericParamDef {
1718 index: type_start + i as u32,
1719 name: param.name.ident().name,
1720 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1721 pure_wrt_drop: param.pure_wrt_drop,
1727 GenericParamKind::Const { default, .. } => {
1728 if !allow_defaults && default.is_some() {
1731 "defaults for const parameters are only allowed in \
1732 `struct`, `enum`, `type`, or `trait` definitions",
1736 let param_def = ty::GenericParamDef {
1737 index: type_start + i as u32,
1738 name: param.name.ident().name,
1739 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1740 pure_wrt_drop: param.pure_wrt_drop,
1741 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1748 // provide junk type parameter defs - the only place that
1749 // cares about anything but the length is instantiation,
1750 // and we don't do that for closures.
1751 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1752 let dummy_args = if gen.is_some() {
1753 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1755 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1758 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1759 index: type_start + i as u32,
1760 name: Symbol::intern(arg),
1762 pure_wrt_drop: false,
1763 kind: ty::GenericParamDefKind::Type {
1765 object_lifetime_default: rl::Set1::Empty,
1771 // provide junk type parameter defs for const blocks.
1772 if let Node::AnonConst(_) = node {
1773 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1774 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1775 params.push(ty::GenericParamDef {
1777 name: Symbol::intern("<const_ty>"),
1779 pure_wrt_drop: false,
1780 kind: ty::GenericParamDefKind::Type {
1782 object_lifetime_default: rl::Set1::Empty,
1789 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1792 parent: parent_def_id,
1795 param_def_id_to_index,
1796 has_self: has_self || parent_has_self,
1797 has_late_bound_regions: has_late_bound_regions(tcx, node),
1801 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1802 generic_args.iter().any(|arg| match arg {
1803 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1804 hir::GenericArg::Infer(_) => true,
1809 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1810 /// use inference to provide suggestions for the appropriate type if possible.
1811 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1816 Slice(ty) => is_suggestable_infer_ty(ty),
1817 Array(ty, length) => {
1818 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1820 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1821 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1822 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1823 Path(hir::QPath::TypeRelative(ty, segment)) => {
1824 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1826 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1827 ty_opt.map_or(false, is_suggestable_infer_ty)
1828 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1834 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1835 if let hir::FnRetTy::Return(ty) = output {
1836 if is_suggestable_infer_ty(ty) {
1843 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1844 use rustc_hir::Node::*;
1847 let def_id = def_id.expect_local();
1848 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1850 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1852 match tcx.hir().get(hir_id) {
1853 TraitItem(hir::TraitItem {
1854 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1858 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => {
1859 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1862 ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => {
1863 // Do not try to inference the return type for a impl method coming from a trait
1864 if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) =
1865 tcx.hir().get(tcx.hir().get_parent_node(hir_id))
1866 && i.of_trait.is_some()
1868 <dyn AstConv<'_>>::ty_of_fn(
1871 sig.header.unsafety,
1878 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1882 TraitItem(hir::TraitItem {
1883 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1886 }) => <dyn AstConv<'_>>::ty_of_fn(
1896 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
1897 let abi = tcx.hir().get_foreign_abi(hir_id);
1898 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi)
1901 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1902 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1904 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1905 ty::Binder::dummy(tcx.mk_fn_sig(
1909 hir::Unsafety::Normal,
1914 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1915 // Closure signatures are not like other function
1916 // signatures and cannot be accessed through `fn_sig`. For
1917 // example, a closure signature excludes the `self`
1918 // argument. In any case they are embedded within the
1919 // closure type as part of the `ClosureSubsts`.
1921 // To get the signature of a closure, you should use the
1922 // `sig` method on the `ClosureSubsts`:
1924 // substs.as_closure().sig(def_id, tcx)
1926 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1931 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1936 fn infer_return_ty_for_fn_sig<'tcx>(
1938 sig: &hir::FnSig<'_>,
1939 generics: &hir::Generics<'_>,
1941 icx: &ItemCtxt<'tcx>,
1942 ) -> ty::PolyFnSig<'tcx> {
1943 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1945 match get_infer_ret_ty(&sig.decl.output) {
1947 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1948 // Typeck doesn't expect erased regions to be returned from `type_of`.
1949 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match *r {
1950 ty::ReErased => tcx.lifetimes.re_static,
1953 let fn_sig = ty::Binder::dummy(fn_sig);
1955 let mut visitor = HirPlaceholderCollector::default();
1956 visitor.visit_ty(ty);
1957 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1958 let ret_ty = fn_sig.skip_binder().output();
1959 if ret_ty.is_suggestable(tcx) {
1960 diag.span_suggestion(
1962 "replace with the correct return type",
1964 Applicability::MachineApplicable,
1966 } else if matches!(ret_ty.kind(), ty::FnDef(..)) {
1967 let fn_sig = ret_ty.fn_sig(tcx);
1968 if fn_sig.skip_binder().inputs_and_output.iter().all(|t| t.is_suggestable(tcx)) {
1969 diag.span_suggestion(
1971 "replace with the correct return type",
1973 Applicability::MachineApplicable,
1976 } else if ret_ty.is_closure() {
1977 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1978 // to prevent the user from getting a papercut while trying to use the unique closure
1979 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1980 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1981 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1987 None => <dyn AstConv<'_>>::ty_of_fn(
1990 sig.header.unsafety,
1999 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
2000 let icx = ItemCtxt::new(tcx, def_id);
2001 match tcx.hir().expect_item(def_id.expect_local()).kind {
2002 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
2003 let selfty = tcx.type_of(def_id);
2004 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
2010 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
2011 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
2012 let item = tcx.hir().expect_item(def_id.expect_local());
2014 hir::ItemKind::Impl(hir::Impl {
2015 polarity: hir::ImplPolarity::Negative(span),
2019 if is_rustc_reservation {
2020 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
2021 tcx.sess.span_err(span, "reservation impls can't be negative");
2023 ty::ImplPolarity::Negative
2025 hir::ItemKind::Impl(hir::Impl {
2026 polarity: hir::ImplPolarity::Positive,
2030 if is_rustc_reservation {
2031 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2033 ty::ImplPolarity::Positive
2035 hir::ItemKind::Impl(hir::Impl {
2036 polarity: hir::ImplPolarity::Positive,
2040 if is_rustc_reservation {
2041 ty::ImplPolarity::Reservation
2043 ty::ImplPolarity::Positive
2046 item => bug!("impl_polarity: {:?} not an impl", item),
2050 /// Returns the early-bound lifetimes declared in this generics
2051 /// listing. For anything other than fns/methods, this is just all
2052 /// the lifetimes that are declared. For fns or methods, we have to
2053 /// screen out those that do not appear in any where-clauses etc using
2054 /// `resolve_lifetime::early_bound_lifetimes`.
2055 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2058 generics: &'a hir::Generics<'a>,
2059 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2060 let late_bound_map = if generics.params.is_empty() {
2061 // This function may be called on `def_id == CRATE_DEF_ID`,
2062 // which makes `is_late_bound_map` ICE. Don't even try if there
2063 // is no generic parameter.
2066 tcx.is_late_bound_map(def_id)
2068 let is_late_bound = move |hir_id| {
2069 let id = tcx.hir().local_def_id(hir_id);
2070 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
2072 generics.params.iter().filter(move |param| match param.kind {
2073 GenericParamKind::Lifetime { .. } => !is_late_bound(param.hir_id),
2078 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2079 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2080 /// inferred constraints concerning which regions outlive other regions.
2081 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2082 debug!("predicates_defined_on({:?})", def_id);
2083 let mut result = tcx.explicit_predicates_of(def_id);
2084 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2085 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2086 if !inferred_outlives.is_empty() {
2088 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2089 def_id, inferred_outlives,
2091 if result.predicates.is_empty() {
2092 result.predicates = inferred_outlives;
2094 result.predicates = tcx
2096 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2100 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2104 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2105 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2106 /// `Self: Trait` predicates for traits.
2107 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2108 let mut result = tcx.predicates_defined_on(def_id);
2110 if tcx.is_trait(def_id) {
2111 // For traits, add `Self: Trait` predicate. This is
2112 // not part of the predicates that a user writes, but it
2113 // is something that one must prove in order to invoke a
2114 // method or project an associated type.
2116 // In the chalk setup, this predicate is not part of the
2117 // "predicates" for a trait item. But it is useful in
2118 // rustc because if you directly (e.g.) invoke a trait
2119 // method like `Trait::method(...)`, you must naturally
2120 // prove that the trait applies to the types that were
2121 // used, and adding the predicate into this list ensures
2122 // that this is done.
2124 // We use a DUMMY_SP here as a way to signal trait bounds that come
2125 // from the trait itself that *shouldn't* be shown as the source of
2126 // an obligation and instead be skipped. Otherwise we'd use
2127 // `tcx.def_span(def_id);`
2128 let span = rustc_span::DUMMY_SP;
2130 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2131 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2135 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2139 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2140 /// N.B., this does not include any implied/inferred constraints.
2141 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2144 debug!("explicit_predicates_of(def_id={:?})", def_id);
2146 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2147 let node = tcx.hir().get(hir_id);
2149 let mut is_trait = None;
2150 let mut is_default_impl_trait = None;
2152 let icx = ItemCtxt::new(tcx, def_id);
2154 const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
2156 // We use an `IndexSet` to preserves order of insertion.
2157 // Preserving the order of insertion is important here so as not to break UI tests.
2158 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2160 let ast_generics = match node {
2161 Node::TraitItem(item) => item.generics,
2163 Node::ImplItem(item) => item.generics,
2165 Node::Item(item) => {
2167 ItemKind::Impl(ref impl_) => {
2168 if impl_.defaultness.is_default() {
2169 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2173 ItemKind::Fn(.., ref generics, _)
2174 | ItemKind::TyAlias(_, ref generics)
2175 | ItemKind::Enum(_, ref generics)
2176 | ItemKind::Struct(_, ref generics)
2177 | ItemKind::Union(_, ref generics) => *generics,
2179 ItemKind::Trait(_, _, ref generics, ..) => {
2180 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2183 ItemKind::TraitAlias(ref generics, _) => {
2184 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2187 ItemKind::OpaqueTy(OpaqueTy {
2188 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2191 // return-position impl trait
2193 // We don't inherit predicates from the parent here:
2194 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2195 // then the return type is `f::<'static, T>::{{opaque}}`.
2197 // If we inherited the predicates of `f` then we would
2198 // require that `T: 'static` to show that the return
2199 // type is well-formed.
2201 // The only way to have something with this opaque type
2202 // is from the return type of the containing function,
2203 // which will ensure that the function's predicates
2205 return ty::GenericPredicates { parent: None, predicates: &[] };
2207 ItemKind::OpaqueTy(OpaqueTy {
2209 origin: hir::OpaqueTyOrigin::TyAlias,
2212 // type-alias impl trait
2220 Node::ForeignItem(item) => match item.kind {
2221 ForeignItemKind::Static(..) => NO_GENERICS,
2222 ForeignItemKind::Fn(_, _, ref generics) => *generics,
2223 ForeignItemKind::Type => NO_GENERICS,
2229 let generics = tcx.generics_of(def_id);
2230 let parent_count = generics.parent_count as u32;
2231 let has_own_self = generics.has_self && parent_count == 0;
2233 // Below we'll consider the bounds on the type parameters (including `Self`)
2234 // and the explicit where-clauses, but to get the full set of predicates
2235 // on a trait we need to add in the supertrait bounds and bounds found on
2236 // associated types.
2237 if let Some(_trait_ref) = is_trait {
2238 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2241 // In default impls, we can assume that the self type implements
2242 // the trait. So in:
2244 // default impl Foo for Bar { .. }
2246 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2247 // (see below). Recall that a default impl is not itself an impl, but rather a
2248 // set of defaults that can be incorporated into another impl.
2249 if let Some(trait_ref) = is_default_impl_trait {
2250 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2253 // Collect the region predicates that were declared inline as
2254 // well. In the case of parameters declared on a fn or method, we
2255 // have to be careful to only iterate over early-bound regions.
2256 let mut index = parent_count
2257 + has_own_self as u32
2258 + early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics).count() as u32;
2260 // Collect the predicates that were written inline by the user on each
2261 // type parameter (e.g., `<T: Foo>`).
2262 for param in ast_generics.params {
2264 // We already dealt with early bound lifetimes above.
2265 GenericParamKind::Lifetime { .. } => (),
2266 GenericParamKind::Type { .. } => {
2267 let name = param.name.ident().name;
2268 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2271 let mut bounds = Bounds::default();
2272 // Params are implicitly sized unless a `?Sized` bound is found
2273 <dyn AstConv<'_>>::add_implicitly_sized(
2277 Some((param.hir_id, ast_generics.predicates)),
2280 predicates.extend(bounds.predicates(tcx, param_ty));
2282 GenericParamKind::Const { .. } => {
2283 // Bounds on const parameters are currently not possible.
2289 // Add in the bounds that appear in the where-clause.
2290 for predicate in ast_generics.predicates {
2292 hir::WherePredicate::BoundPredicate(bound_pred) => {
2293 let ty = icx.to_ty(bound_pred.bounded_ty);
2294 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2296 // Keep the type around in a dummy predicate, in case of no bounds.
2297 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2298 // is still checked for WF.
2299 if bound_pred.bounds.is_empty() {
2300 if let ty::Param(_) = ty.kind() {
2301 // This is a `where T:`, which can be in the HIR from the
2302 // transformation that moves `?Sized` to `T`'s declaration.
2303 // We can skip the predicate because type parameters are
2304 // trivially WF, but also we *should*, to avoid exposing
2305 // users who never wrote `where Type:,` themselves, to
2306 // compiler/tooling bugs from not handling WF predicates.
2308 let span = bound_pred.bounded_ty.span;
2309 let re_root_empty = tcx.lifetimes.re_root_empty;
2310 let predicate = ty::Binder::bind_with_vars(
2311 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2317 predicates.insert((predicate.to_predicate(tcx), span));
2321 let mut bounds = Bounds::default();
2322 <dyn AstConv<'_>>::add_bounds(
2325 bound_pred.bounds.iter(),
2329 predicates.extend(bounds.predicates(tcx, ty));
2332 hir::WherePredicate::RegionPredicate(region_pred) => {
2333 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2334 predicates.extend(region_pred.bounds.iter().map(|bound| {
2335 let (r2, span) = match bound {
2336 hir::GenericBound::Outlives(lt) => {
2337 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2341 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2342 ty::OutlivesPredicate(r1, r2),
2344 .to_predicate(icx.tcx);
2350 hir::WherePredicate::EqPredicate(..) => {
2356 if tcx.features().generic_const_exprs {
2357 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2360 let mut predicates: Vec<_> = predicates.into_iter().collect();
2362 // Subtle: before we store the predicates into the tcx, we
2363 // sort them so that predicates like `T: Foo<Item=U>` come
2364 // before uses of `U`. This avoids false ambiguity errors
2365 // in trait checking. See `setup_constraining_predicates`
2367 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2368 let self_ty = tcx.type_of(def_id);
2369 let trait_ref = tcx.impl_trait_ref(def_id);
2370 cgp::setup_constraining_predicates(
2374 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2378 let result = ty::GenericPredicates {
2379 parent: generics.parent,
2380 predicates: tcx.arena.alloc_from_iter(predicates),
2382 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2386 fn const_evaluatable_predicates_of<'tcx>(
2389 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2390 struct ConstCollector<'tcx> {
2392 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2395 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2396 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2397 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2398 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2399 if let ty::ConstKind::Unevaluated(uv) = ct.val() {
2400 assert_eq!(uv.promoted, None);
2401 let span = self.tcx.hir().span(c.hir_id);
2403 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2404 .to_predicate(self.tcx),
2410 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2411 // Do not look into const param defaults,
2412 // these get checked when they are actually instantiated.
2414 // We do not want the following to error:
2416 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2417 // struct Bar<const N: usize>(Foo<N, 3>);
2421 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2422 let node = tcx.hir().get(hir_id);
2424 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2425 if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
2426 if let Some(of_trait) = &impl_.of_trait {
2427 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2428 collector.visit_trait_ref(of_trait);
2431 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2432 collector.visit_ty(impl_.self_ty);
2435 if let Some(generics) = node.generics() {
2436 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2437 collector.visit_generics(generics);
2440 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2441 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2442 collector.visit_fn_decl(fn_sig.decl);
2444 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2449 fn trait_explicit_predicates_and_bounds(
2452 ) -> ty::GenericPredicates<'_> {
2453 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2454 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2457 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2458 let def_kind = tcx.def_kind(def_id);
2459 if let DefKind::Trait = def_kind {
2460 // Remove bounds on associated types from the predicates, they will be
2461 // returned by `explicit_item_bounds`.
2462 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2463 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2465 let is_assoc_item_ty = |ty: Ty<'_>| {
2466 // For a predicate from a where clause to become a bound on an
2468 // * It must use the identity substs of the item.
2469 // * Since any generic parameters on the item are not in scope,
2470 // this means that the item is not a GAT, and its identity
2471 // substs are the same as the trait's.
2472 // * It must be an associated type for this trait (*not* a
2474 if let ty::Projection(projection) = ty.kind() {
2475 projection.substs == trait_identity_substs
2476 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2482 let predicates: Vec<_> = predicates_and_bounds
2486 .filter(|(pred, _)| match pred.kind().skip_binder() {
2487 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2488 ty::PredicateKind::Projection(proj) => {
2489 !is_assoc_item_ty(proj.projection_ty.self_ty())
2491 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2495 if predicates.len() == predicates_and_bounds.predicates.len() {
2496 predicates_and_bounds
2498 ty::GenericPredicates {
2499 parent: predicates_and_bounds.parent,
2500 predicates: tcx.arena.alloc_slice(&predicates),
2504 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2505 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2506 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2507 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2508 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2509 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2511 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2512 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2513 // ^^^ explicit_predicates_of on
2514 // parent item we dont have set as the
2515 // parent of generics returned by `generics_of`
2517 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2518 let item_def_id = tcx.hir().get_parent_item(hir_id);
2519 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2520 return tcx.explicit_predicates_of(item_def_id);
2523 gather_explicit_predicates_of(tcx, def_id)
2527 /// Converts a specific `GenericBound` from the AST into a set of
2528 /// predicates that apply to the self type. A vector is returned
2529 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2530 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2531 /// and `<T as Bar>::X == i32`).
2532 fn predicates_from_bound<'tcx>(
2533 astconv: &dyn AstConv<'tcx>,
2535 bound: &'tcx hir::GenericBound<'tcx>,
2536 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2537 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2538 let mut bounds = Bounds::default();
2539 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2540 bounds.predicates(astconv.tcx(), param_ty).collect()
2543 fn compute_sig_of_foreign_fn_decl<'tcx>(
2546 decl: &'tcx hir::FnDecl<'tcx>,
2548 ) -> ty::PolyFnSig<'tcx> {
2549 let unsafety = if abi == abi::Abi::RustIntrinsic {
2550 intrinsic_operation_unsafety(tcx.item_name(def_id))
2552 hir::Unsafety::Unsafe
2554 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2555 let fty = <dyn AstConv<'_>>::ty_of_fn(
2556 &ItemCtxt::new(tcx, def_id),
2565 // Feature gate SIMD types in FFI, since I am not sure that the
2566 // ABIs are handled at all correctly. -huonw
2567 if abi != abi::Abi::RustIntrinsic
2568 && abi != abi::Abi::PlatformIntrinsic
2569 && !tcx.features().simd_ffi
2571 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2576 .span_to_snippet(ast_ty.span)
2577 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2582 "use of SIMD type{} in FFI is highly experimental and \
2583 may result in invalid code",
2587 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2591 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2594 if let hir::FnRetTy::Return(ref ty) = decl.output {
2595 check(ty, fty.output().skip_binder())
2602 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2603 match tcx.hir().get_if_local(def_id) {
2604 Some(Node::ForeignItem(..)) => true,
2606 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2610 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2611 match tcx.hir().get_if_local(def_id) {
2612 Some(Node::Expr(&rustc_hir::Expr {
2613 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2615 })) => tcx.hir().body(body_id).generator_kind(),
2617 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2621 fn from_target_feature(
2623 attr: &ast::Attribute,
2624 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2625 target_features: &mut Vec<Symbol>,
2627 let Some(list) = attr.meta_item_list() else { return };
2628 let bad_item = |span| {
2629 let msg = "malformed `target_feature` attribute input";
2630 let code = "enable = \"..\"".to_owned();
2632 .struct_span_err(span, msg)
2633 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2636 let rust_features = tcx.features();
2638 // Only `enable = ...` is accepted in the meta-item list.
2639 if !item.has_name(sym::enable) {
2640 bad_item(item.span());
2644 // Must be of the form `enable = "..."` (a string).
2645 let Some(value) = item.value_str() else {
2646 bad_item(item.span());
2650 // We allow comma separation to enable multiple features.
2651 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2652 let Some(feature_gate) = supported_target_features.get(feature) else {
2654 format!("the feature named `{}` is not valid for this target", feature);
2655 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2658 format!("`{}` is not valid for this target", feature),
2660 if let Some(stripped) = feature.strip_prefix('+') {
2661 let valid = supported_target_features.contains_key(stripped);
2663 err.help("consider removing the leading `+` in the feature name");
2670 // Only allow features whose feature gates have been enabled.
2671 let allowed = match feature_gate.as_ref().copied() {
2672 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2673 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2674 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2675 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2676 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2677 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2678 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2679 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2680 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2681 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2682 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2683 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2684 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2685 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2686 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2687 Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
2688 Some(name) => bug!("unknown target feature gate {}", name),
2693 &tcx.sess.parse_sess,
2694 feature_gate.unwrap(),
2696 &format!("the target feature `{}` is currently unstable", feature),
2700 Some(Symbol::intern(feature))
2705 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage {
2706 use rustc_middle::mir::mono::Linkage::*;
2708 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2709 // applicable to variable declarations and may not really make sense for
2710 // Rust code in the first place but allow them anyway and trust that the
2711 // user knows what they're doing. Who knows, unanticipated use cases may pop
2712 // up in the future.
2714 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2715 // and don't have to be, LLVM treats them as no-ops.
2717 "appending" => Appending,
2718 "available_externally" => AvailableExternally,
2720 "extern_weak" => ExternalWeak,
2721 "external" => External,
2722 "internal" => Internal,
2723 "linkonce" => LinkOnceAny,
2724 "linkonce_odr" => LinkOnceODR,
2725 "private" => Private,
2727 "weak_odr" => WeakODR,
2728 _ => tcx.sess.span_fatal(tcx.def_span(def_id), "invalid linkage specified"),
2732 fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
2733 if cfg!(debug_assertions) {
2734 let def_kind = tcx.def_kind(did);
2736 def_kind.has_codegen_attrs(),
2737 "unexpected `def_kind` in `codegen_fn_attrs`: {def_kind:?}",
2741 let did = did.expect_local();
2742 let attrs = tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(did));
2743 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2744 if tcx.should_inherit_track_caller(did) {
2745 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2748 // The panic_no_unwind function called by TerminatorKind::Abort will never
2749 // unwind. If the panic handler that it invokes unwind then it will simply
2750 // call the panic handler again.
2751 if Some(did.to_def_id()) == tcx.lang_items().panic_no_unwind() {
2752 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2755 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2757 let mut inline_span = None;
2758 let mut link_ordinal_span = None;
2759 let mut no_sanitize_span = None;
2760 for attr in attrs.iter() {
2761 if attr.has_name(sym::cold) {
2762 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2763 } else if attr.has_name(sym::rustc_allocator) {
2764 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2765 } else if attr.has_name(sym::ffi_returns_twice) {
2766 if tcx.is_foreign_item(did) {
2767 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2769 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2774 "`#[ffi_returns_twice]` may only be used on foreign functions"
2778 } else if attr.has_name(sym::ffi_pure) {
2779 if tcx.is_foreign_item(did) {
2780 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2781 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2786 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2790 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2793 // `#[ffi_pure]` is only allowed on foreign functions
2798 "`#[ffi_pure]` may only be used on foreign functions"
2802 } else if attr.has_name(sym::ffi_const) {
2803 if tcx.is_foreign_item(did) {
2804 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2806 // `#[ffi_const]` is only allowed on foreign functions
2811 "`#[ffi_const]` may only be used on foreign functions"
2815 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2816 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2817 } else if attr.has_name(sym::naked) {
2818 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2819 } else if attr.has_name(sym::no_mangle) {
2820 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2821 } else if attr.has_name(sym::no_coverage) {
2822 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2823 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2824 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2825 } else if attr.has_name(sym::used) {
2826 let inner = attr.meta_item_list();
2827 match inner.as_deref() {
2828 Some([item]) if item.has_name(sym::linker) => {
2829 if !tcx.features().used_with_arg {
2831 &tcx.sess.parse_sess,
2834 "`#[used(linker)]` is currently unstable",
2838 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2840 Some([item]) if item.has_name(sym::compiler) => {
2841 if !tcx.features().used_with_arg {
2843 &tcx.sess.parse_sess,
2846 "`#[used(compiler)]` is currently unstable",
2850 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2856 "expected `used`, `used(compiler)` or `used(linker)`",
2860 None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
2862 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2863 if !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. }) {
2868 "`#[cmse_nonsecure_entry]` requires C ABI"
2872 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2873 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2876 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2877 } else if attr.has_name(sym::thread_local) {
2878 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2879 } else if attr.has_name(sym::track_caller) {
2880 if !tcx.is_closure(did.to_def_id()) && tcx.fn_sig(did).abi() != abi::Abi::Rust {
2881 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2884 if tcx.is_closure(did.to_def_id()) && !tcx.features().closure_track_caller {
2886 &tcx.sess.parse_sess,
2887 sym::closure_track_caller,
2889 "`#[track_caller]` on closures is currently unstable",
2893 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2894 } else if attr.has_name(sym::export_name) {
2895 if let Some(s) = attr.value_str() {
2896 if s.as_str().contains('\0') {
2897 // `#[export_name = ...]` will be converted to a null-terminated string,
2898 // so it may not contain any null characters.
2903 "`export_name` may not contain null characters"
2907 codegen_fn_attrs.export_name = Some(s);
2909 } else if attr.has_name(sym::target_feature) {
2910 if !tcx.is_closure(did.to_def_id())
2911 && tcx.fn_sig(did).unsafety() == hir::Unsafety::Normal
2913 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2914 // The `#[target_feature]` attribute is allowed on
2915 // WebAssembly targets on all functions, including safe
2916 // ones. Other targets require that `#[target_feature]` is
2917 // only applied to unsafe functions (pending the
2918 // `target_feature_11` feature) because on most targets
2919 // execution of instructions that are not supported is
2920 // considered undefined behavior. For WebAssembly which is a
2921 // 100% safe target at execution time it's not possible to
2922 // execute undefined instructions, and even if a future
2923 // feature was added in some form for this it would be a
2924 // deterministic trap. There is no undefined behavior when
2925 // executing WebAssembly so `#[target_feature]` is allowed
2926 // on safe functions (but again, only for WebAssembly)
2928 // Note that this is also allowed if `actually_rustdoc` so
2929 // if a target is documenting some wasm-specific code then
2930 // it's not spuriously denied.
2931 } else if !tcx.features().target_feature_11 {
2932 let mut err = feature_err(
2933 &tcx.sess.parse_sess,
2934 sym::target_feature_11,
2936 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2938 err.span_label(tcx.def_span(did), "not an `unsafe` function");
2941 check_target_feature_trait_unsafe(tcx, did, attr.span);
2944 from_target_feature(
2947 supported_target_features,
2948 &mut codegen_fn_attrs.target_features,
2950 } else if attr.has_name(sym::linkage) {
2951 if let Some(val) = attr.value_str() {
2952 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, did, val.as_str()));
2954 } else if attr.has_name(sym::link_section) {
2955 if let Some(val) = attr.value_str() {
2956 if val.as_str().bytes().any(|b| b == 0) {
2958 "illegal null byte in link_section \
2962 tcx.sess.span_err(attr.span, &msg);
2964 codegen_fn_attrs.link_section = Some(val);
2967 } else if attr.has_name(sym::link_name) {
2968 codegen_fn_attrs.link_name = attr.value_str();
2969 } else if attr.has_name(sym::link_ordinal) {
2970 link_ordinal_span = Some(attr.span);
2971 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2972 codegen_fn_attrs.link_ordinal = ordinal;
2974 } else if attr.has_name(sym::no_sanitize) {
2975 no_sanitize_span = Some(attr.span);
2976 if let Some(list) = attr.meta_item_list() {
2977 for item in list.iter() {
2978 if item.has_name(sym::address) {
2979 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2980 } else if item.has_name(sym::cfi) {
2981 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2982 } else if item.has_name(sym::memory) {
2983 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2984 } else if item.has_name(sym::memtag) {
2985 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
2986 } else if item.has_name(sym::thread) {
2987 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2988 } else if item.has_name(sym::hwaddress) {
2989 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2992 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2993 .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, or `thread`")
2998 } else if attr.has_name(sym::instruction_set) {
2999 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
3000 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
3001 [NestedMetaItem::MetaItem(set)] => {
3003 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
3004 match segments.as_slice() {
3005 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3006 if !tcx.sess.target.has_thumb_interworking {
3008 tcx.sess.diagnostic(),
3011 "target does not support `#[instruction_set]`"
3015 } else if segments[1] == sym::a32 {
3016 Some(InstructionSetAttr::ArmA32)
3017 } else if segments[1] == sym::t32 {
3018 Some(InstructionSetAttr::ArmT32)
3025 tcx.sess.diagnostic(),
3028 "invalid instruction set specified",
3037 tcx.sess.diagnostic(),
3040 "`#[instruction_set]` requires an argument"
3047 tcx.sess.diagnostic(),
3050 "cannot specify more than one instruction set"
3058 tcx.sess.diagnostic(),
3061 "must specify an instruction set"
3067 } else if attr.has_name(sym::repr) {
3068 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3069 Some(items) => match items.as_slice() {
3070 [item] => match item.name_value_literal() {
3071 Some((sym::align, literal)) => {
3072 let alignment = rustc_attr::parse_alignment(&literal.kind);
3075 Ok(align) => Some(align),
3078 tcx.sess.diagnostic(),
3081 "invalid `repr(align)` attribute: {}",
3100 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3101 if !attr.has_name(sym::inline) {
3104 match attr.meta_kind() {
3105 Some(MetaItemKind::Word) => InlineAttr::Hint,
3106 Some(MetaItemKind::List(ref items)) => {
3107 inline_span = Some(attr.span);
3108 if items.len() != 1 {
3110 tcx.sess.diagnostic(),
3113 "expected one argument"
3117 } else if list_contains_name(&items, sym::always) {
3119 } else if list_contains_name(&items, sym::never) {
3123 tcx.sess.diagnostic(),
3133 Some(MetaItemKind::NameValue(_)) => ia,
3138 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3139 if !attr.has_name(sym::optimize) {
3142 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3143 match attr.meta_kind() {
3144 Some(MetaItemKind::Word) => {
3145 err(attr.span, "expected one argument");
3148 Some(MetaItemKind::List(ref items)) => {
3149 inline_span = Some(attr.span);
3150 if items.len() != 1 {
3151 err(attr.span, "expected one argument");
3153 } else if list_contains_name(&items, sym::size) {
3155 } else if list_contains_name(&items, sym::speed) {
3158 err(items[0].span(), "invalid argument");
3162 Some(MetaItemKind::NameValue(_)) => ia,
3167 // #73631: closures inherit `#[target_feature]` annotations
3168 if tcx.features().target_feature_11 && tcx.is_closure(did.to_def_id()) {
3169 let owner_id = tcx.parent(did.to_def_id());
3172 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3175 // If a function uses #[target_feature] it can't be inlined into general
3176 // purpose functions as they wouldn't have the right target features
3177 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3179 if !codegen_fn_attrs.target_features.is_empty() {
3180 if codegen_fn_attrs.inline == InlineAttr::Always {
3181 if let Some(span) = inline_span {
3184 "cannot use `#[inline(always)]` with \
3185 `#[target_feature]`",
3191 if !codegen_fn_attrs.no_sanitize.is_empty() {
3192 if codegen_fn_attrs.inline == InlineAttr::Always {
3193 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3194 let hir_id = tcx.hir().local_def_id_to_hir_id(did);
3195 tcx.struct_span_lint_hir(
3196 lint::builtin::INLINE_NO_SANITIZE,
3200 lint.build("`no_sanitize` will have no effect after inlining")
3201 .span_note(inline_span, "inlining requested here")
3209 // Weak lang items have the same semantics as "std internal" symbols in the
3210 // sense that they're preserved through all our LTO passes and only
3211 // strippable by the linker.
3213 // Additionally weak lang items have predetermined symbol names.
3214 if tcx.is_weak_lang_item(did.to_def_id()) {
3215 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3217 if let Some(name) = weak_lang_items::link_name(attrs) {
3218 codegen_fn_attrs.export_name = Some(name);
3219 codegen_fn_attrs.link_name = Some(name);
3221 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3223 // Internal symbols to the standard library all have no_mangle semantics in
3224 // that they have defined symbol names present in the function name. This
3225 // also applies to weak symbols where they all have known symbol names.
3226 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3227 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3230 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3231 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3232 // intrinsic functions.
3233 if let Some(name) = &codegen_fn_attrs.link_name {
3234 if name.as_str().starts_with("llvm.") {
3235 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3242 /// Computes the set of target features used in a function for the purposes of
3243 /// inline assembly.
3244 fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx FxHashSet<Symbol> {
3245 let mut target_features = tcx.sess.target_features.clone();
3246 if tcx.def_kind(did).has_codegen_attrs() {
3247 let attrs = tcx.codegen_fn_attrs(did);
3248 target_features.extend(&attrs.target_features);
3249 match attrs.instruction_set {
3251 Some(InstructionSetAttr::ArmA32) => {
3252 target_features.remove(&sym::thumb_mode);
3254 Some(InstructionSetAttr::ArmT32) => {
3255 target_features.insert(sym::thumb_mode);
3260 tcx.arena.alloc(target_features)
3263 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3264 /// applied to the method prototype.
3265 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3266 if let Some(impl_item) = tcx.opt_associated_item(def_id)
3267 && let ty::AssocItemContainer::ImplContainer(_) = impl_item.container
3268 && let Some(trait_item) = impl_item.trait_item_def_id
3271 .codegen_fn_attrs(trait_item)
3273 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3279 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3280 use rustc_ast::{Lit, LitIntType, LitKind};
3281 let meta_item_list = attr.meta_item_list();
3282 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3283 let sole_meta_list = match meta_item_list {
3284 Some([item]) => item.literal(),
3287 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3288 .note("the attribute requires exactly one argument")
3294 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3295 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3296 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3297 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3298 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3300 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3301 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3302 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3303 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3304 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3305 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3306 // about LINK.EXE failing.)
3307 if *ordinal <= u16::MAX as u128 {
3308 Some(*ordinal as u16)
3310 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3312 .struct_span_err(attr.span, &msg)
3313 .note("the value may not exceed `u16::MAX`")
3319 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3320 .note("an unsuffixed integer value, e.g., `1`, is expected")
3326 fn check_link_name_xor_ordinal(
3328 codegen_fn_attrs: &CodegenFnAttrs,
3329 inline_span: Option<Span>,
3331 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3334 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3335 if let Some(span) = inline_span {
3336 tcx.sess.span_err(span, msg);
3342 /// Checks the function annotated with `#[target_feature]` is not a safe
3343 /// trait method implementation, reporting an error if it is.
3344 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3345 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3346 let node = tcx.hir().get(hir_id);
3347 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3348 let parent_id = tcx.hir().get_parent_item(hir_id);
3349 let parent_item = tcx.hir().expect_item(parent_id);
3350 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3354 "`#[target_feature(..)]` cannot be applied to safe trait method",
3356 .span_label(attr_span, "cannot be applied to safe trait method")
3357 .span_label(tcx.def_span(id), "not an `unsafe` function")