1 // ignore-tidy-filelength
2 //! "Collection" is the process of determining the type and other external
3 //! details of each item in Rust. Collection is specifically concerned
4 //! with *inter-procedural* things -- for example, for a function
5 //! definition, collection will figure out the type and signature of the
6 //! function, but it will not visit the *body* of the function in any way,
7 //! nor examine type annotations on local variables (that's the job of
10 //! Collecting is ultimately defined by a bundle of queries that
11 //! inquire after various facts about the items in the crate (e.g.,
12 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
15 //! At present, however, we do run collection across all items in the
16 //! crate as a kind of pass. This should eventually be factored away.
18 use crate::astconv::AstConv;
19 use crate::bounds::Bounds;
20 use crate::check::intrinsic::intrinsic_operation_unsafety;
21 use crate::constrained_generic_params as cgp;
23 use crate::middle::resolve_lifetime as rl;
25 use rustc_ast::{MetaItemKind, NestedMetaItem};
26 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
27 use rustc_data_structures::captures::Captures;
28 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
29 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
31 use rustc_hir::def::{CtorKind, DefKind};
32 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
33 use rustc_hir::intravisit::{self, Visitor};
34 use rustc_hir::weak_lang_items;
35 use rustc_hir::{GenericParamKind, HirId, Node};
36 use rustc_middle::hir::nested_filter;
37 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
38 use rustc_middle::mir::mono::Linkage;
39 use rustc_middle::ty::query::Providers;
40 use rustc_middle::ty::subst::InternalSubsts;
41 use rustc_middle::ty::util::Discr;
42 use rustc_middle::ty::util::IntTypeExt;
43 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
44 use rustc_middle::ty::{ReprOptions, ToPredicate};
45 use rustc_session::lint;
46 use rustc_session::parse::feature_err;
47 use rustc_span::symbol::{kw, sym, Ident, Symbol};
48 use rustc_span::{Span, DUMMY_SP};
49 use rustc_target::spec::{abi, PanicStrategy, SanitizerSet};
50 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
56 struct OnlySelfBounds(bool);
58 ///////////////////////////////////////////////////////////////////////////
61 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
62 tcx.hir().visit_item_likes_in_module(
64 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
68 pub fn provide(providers: &mut Providers) {
69 *providers = Providers {
70 opt_const_param_of: type_of::opt_const_param_of,
71 type_of: type_of::type_of,
72 item_bounds: item_bounds::item_bounds,
73 explicit_item_bounds: item_bounds::explicit_item_bounds,
76 predicates_defined_on,
77 explicit_predicates_of,
79 super_predicates_that_define_assoc_type,
80 trait_explicit_predicates_and_bounds,
81 type_param_predicates,
91 collect_mod_item_types,
92 should_inherit_track_caller,
97 ///////////////////////////////////////////////////////////////////////////
99 /// Context specific to some particular item. This is what implements
100 /// `AstConv`. It has information about the predicates that are defined
101 /// on the trait. Unfortunately, this predicate information is
102 /// available in various different forms at various points in the
103 /// process. So we can't just store a pointer to e.g., the AST or the
104 /// parsed ty form, we have to be more flexible. To this end, the
105 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
106 /// `get_type_parameter_bounds` requests, drawing the information from
107 /// the AST (`hir::Generics`), recursively.
108 pub struct ItemCtxt<'tcx> {
113 ///////////////////////////////////////////////////////////////////////////
116 crate struct HirPlaceholderCollector(crate Vec<Span>);
118 impl<'v> Visitor<'v> for HirPlaceholderCollector {
119 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
120 if let hir::TyKind::Infer = t.kind {
123 intravisit::walk_ty(self, t)
125 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
127 hir::GenericArg::Infer(inf) => {
128 self.0.push(inf.span);
129 intravisit::walk_inf(self, inf);
131 hir::GenericArg::Type(t) => self.visit_ty(t),
135 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
136 if let &hir::ArrayLen::Infer(_, span) = length {
139 intravisit::walk_array_len(self, length)
143 struct CollectItemTypesVisitor<'tcx> {
147 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
148 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
149 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
150 crate fn placeholder_type_error<'tcx>(
153 generics: &[hir::GenericParam<'_>],
154 placeholder_types: Vec<Span>,
156 hir_ty: Option<&hir::Ty<'_>>,
159 if placeholder_types.is_empty() {
163 placeholder_type_error_diag(
176 crate fn placeholder_type_error_diag<'tcx>(
179 generics: &[hir::GenericParam<'_>],
180 placeholder_types: Vec<Span>,
181 additional_spans: Vec<Span>,
183 hir_ty: Option<&hir::Ty<'_>>,
185 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
186 if placeholder_types.is_empty() {
187 return bad_placeholder(tcx, additional_spans, kind);
190 let type_name = generics.next_type_param_name(None);
191 let mut sugg: Vec<_> =
192 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
194 if generics.is_empty() {
195 if let Some(span) = span {
196 sugg.push((span, format!("<{}>", type_name)));
198 } else if let Some(arg) = generics
200 .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
202 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
203 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
204 sugg.push((arg.span, (*type_name).to_string()));
206 let last = generics.iter().last().unwrap();
207 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
208 let span = last.bounds_span_for_suggestions().unwrap_or(last.span.shrink_to_hi());
209 sugg.push((span, format!(", {}", type_name)));
213 bad_placeholder(tcx, placeholder_types.into_iter().chain(additional_spans).collect(), kind);
215 // Suggest, but only if it is not a function in const or static
217 let mut is_fn = false;
218 let mut is_const_or_static = false;
220 if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind {
223 // Check if parent is const or static
224 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
225 let parent_node = tcx.hir().get(parent_id);
227 is_const_or_static = matches!(
229 Node::Item(&hir::Item {
230 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
232 }) | Node::TraitItem(&hir::TraitItem {
233 kind: hir::TraitItemKind::Const(..),
235 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
239 // if function is wrapped around a const or static,
240 // then don't show the suggestion
241 if !(is_fn && is_const_or_static) {
242 err.multipart_suggestion(
243 "use type parameters instead",
245 Applicability::HasPlaceholders,
253 fn reject_placeholder_type_signatures_in_item<'tcx>(
255 item: &'tcx hir::Item<'tcx>,
257 let (generics, suggest) = match &item.kind {
258 hir::ItemKind::Union(_, generics)
259 | hir::ItemKind::Enum(_, generics)
260 | hir::ItemKind::TraitAlias(generics, _)
261 | hir::ItemKind::Trait(_, _, generics, ..)
262 | hir::ItemKind::Impl(hir::Impl { generics, .. })
263 | hir::ItemKind::Struct(_, generics) => (generics, true),
264 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
265 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
266 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
270 let mut visitor = HirPlaceholderCollector::default();
271 visitor.visit_item(item);
273 placeholder_type_error(
284 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
285 type NestedFilter = nested_filter::OnlyBodies;
287 fn nested_visit_map(&mut self) -> Self::Map {
291 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
292 convert_item(self.tcx, item.item_id());
293 reject_placeholder_type_signatures_in_item(self.tcx, item);
294 intravisit::walk_item(self, item);
297 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
298 for param in generics.params {
300 hir::GenericParamKind::Lifetime { .. } => {}
301 hir::GenericParamKind::Type { default: Some(_), .. } => {
302 let def_id = self.tcx.hir().local_def_id(param.hir_id);
303 self.tcx.ensure().type_of(def_id);
305 hir::GenericParamKind::Type { .. } => {}
306 hir::GenericParamKind::Const { default, .. } => {
307 let def_id = self.tcx.hir().local_def_id(param.hir_id);
308 self.tcx.ensure().type_of(def_id);
309 if let Some(default) = default {
310 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
311 // need to store default and type of default
312 self.tcx.ensure().type_of(default_def_id);
313 self.tcx.ensure().const_param_default(def_id);
318 intravisit::walk_generics(self, generics);
321 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
322 if let hir::ExprKind::Closure(..) = expr.kind {
323 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
324 self.tcx.ensure().generics_of(def_id);
325 // We do not call `type_of` for closures here as that
326 // depends on typecheck and would therefore hide
327 // any further errors in case one typeck fails.
329 intravisit::walk_expr(self, expr);
332 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
333 convert_trait_item(self.tcx, trait_item.trait_item_id());
334 intravisit::walk_trait_item(self, trait_item);
337 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
338 convert_impl_item(self.tcx, impl_item.impl_item_id());
339 intravisit::walk_impl_item(self, impl_item);
343 ///////////////////////////////////////////////////////////////////////////
344 // Utility types and common code for the above passes.
346 fn bad_placeholder<'tcx>(
348 mut spans: Vec<Span>,
350 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
351 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
354 let mut err = struct_span_err!(
358 "the placeholder `_` is not allowed within types on item signatures for {}",
362 err.span_label(span, "not allowed in type signatures");
367 impl<'tcx> ItemCtxt<'tcx> {
368 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
369 ItemCtxt { tcx, item_def_id }
372 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
373 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
376 pub fn hir_id(&self) -> hir::HirId {
377 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
380 pub fn node(&self) -> hir::Node<'tcx> {
381 self.tcx.hir().get(self.hir_id())
385 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
386 fn tcx(&self) -> TyCtxt<'tcx> {
390 fn item_def_id(&self) -> Option<DefId> {
391 Some(self.item_def_id)
394 fn get_type_parameter_bounds(
399 ) -> ty::GenericPredicates<'tcx> {
400 self.tcx.at(span).type_param_predicates((
402 def_id.expect_local(),
407 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
411 fn allow_ty_infer(&self) -> bool {
415 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
416 self.tcx().ty_error_with_message(span, "bad placeholder type")
419 fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
420 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match *r {
421 ty::ReErased => self.tcx.lifetimes.re_static,
424 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
427 fn projected_ty_from_poly_trait_ref(
431 item_segment: &hir::PathSegment<'_>,
432 poly_trait_ref: ty::PolyTraitRef<'tcx>,
434 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
435 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
443 self.tcx().mk_projection(item_def_id, item_substs)
445 // There are no late-bound regions; we can just ignore the binder.
446 let mut err = struct_span_err!(
450 "cannot use the associated type of a trait \
451 with uninferred generic parameters"
455 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
457 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
459 hir::ItemKind::Enum(_, generics)
460 | hir::ItemKind::Struct(_, generics)
461 | hir::ItemKind::Union(_, generics) => {
462 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
463 let (lt_sp, sugg) = match generics.params {
464 [] => (generics.span, format!("<{}>", lt_name)),
466 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
469 let suggestions = vec![
472 span.with_hi(item_segment.ident.span.lo()),
475 // Replace the existing lifetimes with a new named lifetime.
477 .replace_late_bound_regions(poly_trait_ref, |_| {
478 self.tcx.mk_region(ty::ReEarlyBound(
479 ty::EarlyBoundRegion {
482 name: Symbol::intern(<_name),
490 err.multipart_suggestion(
491 "use a fully qualified path with explicit lifetimes",
493 Applicability::MaybeIncorrect,
499 hir::Node::Item(hir::Item {
501 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
505 | hir::Node::ForeignItem(_)
506 | hir::Node::TraitItem(_)
507 | hir::Node::ImplItem(_) => {
508 err.span_suggestion_verbose(
509 span.with_hi(item_segment.ident.span.lo()),
510 "use a fully qualified path with inferred lifetimes",
513 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
514 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
516 Applicability::MaybeIncorrect,
522 self.tcx().ty_error()
526 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
527 // Types in item signatures are not normalized to avoid undue dependencies.
531 fn set_tainted_by_errors(&self) {
532 // There's no obvious place to track this, so just let it go.
535 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
536 // There's no place to record types from signatures?
540 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
541 fn get_new_lifetime_name<'tcx>(
543 poly_trait_ref: ty::PolyTraitRef<'tcx>,
544 generics: &hir::Generics<'tcx>,
546 let existing_lifetimes = tcx
547 .collect_referenced_late_bound_regions(&poly_trait_ref)
550 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
551 Some(name.as_str().to_string())
556 .chain(generics.params.iter().filter_map(|param| {
557 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
558 Some(param.name.ident().as_str().to_string())
563 .collect::<FxHashSet<String>>();
565 let a_to_z_repeat_n = |n| {
566 (b'a'..=b'z').map(move |c| {
567 let mut s = '\''.to_string();
568 s.extend(std::iter::repeat(char::from(c)).take(n));
573 // If all single char lifetime names are present, we wrap around and double the chars.
574 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
577 /// Returns the predicates defined on `item_def_id` of the form
578 /// `X: Foo` where `X` is the type parameter `def_id`.
579 fn type_param_predicates(
581 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
582 ) -> ty::GenericPredicates<'_> {
585 // In the AST, bounds can derive from two places. Either
586 // written inline like `<T: Foo>` or in a where-clause like
589 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
590 let param_owner = tcx.hir().ty_param_owner(def_id);
591 let generics = tcx.generics_of(param_owner);
592 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
593 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
595 // Don't look for bounds where the type parameter isn't in scope.
596 let parent = if item_def_id == param_owner.to_def_id() {
599 tcx.generics_of(item_def_id).parent
602 let mut result = parent
604 let icx = ItemCtxt::new(tcx, parent);
605 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
607 .unwrap_or_default();
608 let mut extend = None;
610 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
611 let ast_generics = match tcx.hir().get(item_hir_id) {
612 Node::TraitItem(item) => &item.generics,
614 Node::ImplItem(item) => &item.generics,
616 Node::Item(item) => {
618 ItemKind::Fn(.., ref generics, _)
619 | ItemKind::Impl(hir::Impl { ref generics, .. })
620 | ItemKind::TyAlias(_, ref generics)
621 | ItemKind::OpaqueTy(OpaqueTy {
623 origin: hir::OpaqueTyOrigin::TyAlias,
626 | ItemKind::Enum(_, ref generics)
627 | ItemKind::Struct(_, ref generics)
628 | ItemKind::Union(_, ref generics) => generics,
629 ItemKind::Trait(_, _, ref generics, ..) => {
630 // Implied `Self: Trait` and supertrait bounds.
631 if param_id == item_hir_id {
632 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
634 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
642 Node::ForeignItem(item) => match item.kind {
643 ForeignItemKind::Fn(_, _, ref generics) => generics,
650 let icx = ItemCtxt::new(tcx, item_def_id);
651 let extra_predicates = extend.into_iter().chain(
652 icx.type_parameter_bounds_in_generics(
656 OnlySelfBounds(true),
660 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
661 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
666 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
670 impl<'tcx> ItemCtxt<'tcx> {
671 /// Finds bounds from `hir::Generics`. This requires scanning through the
672 /// AST. We do this to avoid having to convert *all* the bounds, which
673 /// would create artificial cycles. Instead, we can only convert the
674 /// bounds for a type parameter `X` if `X::Foo` is used.
675 fn type_parameter_bounds_in_generics(
677 ast_generics: &'tcx hir::Generics<'tcx>,
678 param_id: hir::HirId,
680 only_self_bounds: OnlySelfBounds,
681 assoc_name: Option<Ident>,
682 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
683 let from_ty_params = ast_generics
686 .filter_map(|param| match param.kind {
687 GenericParamKind::Type { .. } | GenericParamKind::Const { .. }
688 if param.hir_id == param_id =>
694 .flat_map(|bounds| bounds.iter())
695 .filter(|b| match assoc_name {
696 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
699 .flat_map(|b| predicates_from_bound(self, ty, b, ty::List::empty()));
701 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
702 let from_where_clauses = ast_generics
706 .filter_map(|wp| match *wp {
707 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
711 let bt = if bp.is_param_bound(param_def_id) {
713 } else if !only_self_bounds.0 {
714 Some(self.to_ty(bp.bounded_ty))
718 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
722 .filter(|b| match assoc_name {
723 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
726 .filter_map(move |b| bt.map(|bt| (bt, b, bvars)))
728 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars));
730 from_ty_params.chain(from_where_clauses).collect()
733 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
734 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
737 hir::GenericBound::Trait(poly_trait_ref, _) => {
738 let trait_ref = &poly_trait_ref.trait_ref;
739 if let Some(trait_did) = trait_ref.trait_def_id() {
740 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
750 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
751 let it = tcx.hir().item(item_id);
752 debug!("convert: item {} with id {}", it.ident, it.hir_id());
753 let def_id = item_id.def_id;
756 // These don't define types.
757 hir::ItemKind::ExternCrate(_)
758 | hir::ItemKind::Use(..)
759 | hir::ItemKind::Macro(..)
760 | hir::ItemKind::Mod(_)
761 | hir::ItemKind::GlobalAsm(_) => {}
762 hir::ItemKind::ForeignMod { items, .. } => {
764 let item = tcx.hir().foreign_item(item.id);
765 tcx.ensure().generics_of(item.def_id);
766 tcx.ensure().type_of(item.def_id);
767 tcx.ensure().predicates_of(item.def_id);
769 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
770 hir::ForeignItemKind::Static(..) => {
771 let mut visitor = HirPlaceholderCollector::default();
772 visitor.visit_foreign_item(item);
773 placeholder_type_error(
787 hir::ItemKind::Enum(ref enum_definition, _) => {
788 tcx.ensure().generics_of(def_id);
789 tcx.ensure().type_of(def_id);
790 tcx.ensure().predicates_of(def_id);
791 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
793 hir::ItemKind::Impl { .. } => {
794 tcx.ensure().generics_of(def_id);
795 tcx.ensure().type_of(def_id);
796 tcx.ensure().impl_trait_ref(def_id);
797 tcx.ensure().predicates_of(def_id);
799 hir::ItemKind::Trait(..) => {
800 tcx.ensure().generics_of(def_id);
801 tcx.ensure().trait_def(def_id);
802 tcx.at(it.span).super_predicates_of(def_id);
803 tcx.ensure().predicates_of(def_id);
805 hir::ItemKind::TraitAlias(..) => {
806 tcx.ensure().generics_of(def_id);
807 tcx.at(it.span).super_predicates_of(def_id);
808 tcx.ensure().predicates_of(def_id);
810 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
811 tcx.ensure().generics_of(def_id);
812 tcx.ensure().type_of(def_id);
813 tcx.ensure().predicates_of(def_id);
815 for f in struct_def.fields() {
816 let def_id = tcx.hir().local_def_id(f.hir_id);
817 tcx.ensure().generics_of(def_id);
818 tcx.ensure().type_of(def_id);
819 tcx.ensure().predicates_of(def_id);
822 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
823 convert_variant_ctor(tcx, ctor_hir_id);
827 // Desugared from `impl Trait`, so visited by the function's return type.
828 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
829 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
833 // Don't call `type_of` on opaque types, since that depends on type
834 // checking function bodies. `check_item_type` ensures that it's called
836 hir::ItemKind::OpaqueTy(..) => {
837 tcx.ensure().generics_of(def_id);
838 tcx.ensure().predicates_of(def_id);
839 tcx.ensure().explicit_item_bounds(def_id);
841 hir::ItemKind::TyAlias(..)
842 | hir::ItemKind::Static(..)
843 | hir::ItemKind::Const(..)
844 | hir::ItemKind::Fn(..) => {
845 tcx.ensure().generics_of(def_id);
846 tcx.ensure().type_of(def_id);
847 tcx.ensure().predicates_of(def_id);
849 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
850 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
851 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
852 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
853 if let hir::TyKind::TraitObject(..) = ty.kind {
854 let mut visitor = HirPlaceholderCollector::default();
855 visitor.visit_item(it);
856 placeholder_type_error(
873 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
874 let trait_item = tcx.hir().trait_item(trait_item_id);
875 tcx.ensure().generics_of(trait_item_id.def_id);
877 match trait_item.kind {
878 hir::TraitItemKind::Fn(..) => {
879 tcx.ensure().type_of(trait_item_id.def_id);
880 tcx.ensure().fn_sig(trait_item_id.def_id);
883 hir::TraitItemKind::Const(.., Some(_)) => {
884 tcx.ensure().type_of(trait_item_id.def_id);
887 hir::TraitItemKind::Const(..) => {
888 tcx.ensure().type_of(trait_item_id.def_id);
889 // Account for `const C: _;`.
890 let mut visitor = HirPlaceholderCollector::default();
891 visitor.visit_trait_item(trait_item);
892 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
895 hir::TraitItemKind::Type(_, Some(_)) => {
896 tcx.ensure().item_bounds(trait_item_id.def_id);
897 tcx.ensure().type_of(trait_item_id.def_id);
898 // Account for `type T = _;`.
899 let mut visitor = HirPlaceholderCollector::default();
900 visitor.visit_trait_item(trait_item);
901 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
904 hir::TraitItemKind::Type(_, None) => {
905 tcx.ensure().item_bounds(trait_item_id.def_id);
906 // #74612: Visit and try to find bad placeholders
907 // even if there is no concrete type.
908 let mut visitor = HirPlaceholderCollector::default();
909 visitor.visit_trait_item(trait_item);
911 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
915 tcx.ensure().predicates_of(trait_item_id.def_id);
918 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
919 let def_id = impl_item_id.def_id;
920 tcx.ensure().generics_of(def_id);
921 tcx.ensure().type_of(def_id);
922 tcx.ensure().predicates_of(def_id);
923 let impl_item = tcx.hir().impl_item(impl_item_id);
924 match impl_item.kind {
925 hir::ImplItemKind::Fn(..) => {
926 tcx.ensure().fn_sig(def_id);
928 hir::ImplItemKind::TyAlias(_) => {
929 // Account for `type T = _;`
930 let mut visitor = HirPlaceholderCollector::default();
931 visitor.visit_impl_item(impl_item);
933 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
935 hir::ImplItemKind::Const(..) => {}
939 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
940 let def_id = tcx.hir().local_def_id(ctor_id);
941 tcx.ensure().generics_of(def_id);
942 tcx.ensure().type_of(def_id);
943 tcx.ensure().predicates_of(def_id);
946 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
947 let def = tcx.adt_def(def_id);
948 let repr_type = def.repr().discr_type();
949 let initial = repr_type.initial_discriminant(tcx);
950 let mut prev_discr = None::<Discr<'_>>;
952 // fill the discriminant values and field types
953 for variant in variants {
954 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
956 if let Some(ref e) = variant.disr_expr {
957 let expr_did = tcx.hir().local_def_id(e.hir_id);
958 def.eval_explicit_discr(tcx, expr_did.to_def_id())
959 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
962 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
965 format!("overflowed on value after {}", prev_discr.unwrap()),
968 "explicitly set `{} = {}` if that is desired outcome",
969 variant.ident, wrapped_discr
974 .unwrap_or(wrapped_discr),
977 for f in variant.data.fields() {
978 let def_id = tcx.hir().local_def_id(f.hir_id);
979 tcx.ensure().generics_of(def_id);
980 tcx.ensure().type_of(def_id);
981 tcx.ensure().predicates_of(def_id);
984 // Convert the ctor, if any. This also registers the variant as
986 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
987 convert_variant_ctor(tcx, ctor_hir_id);
994 variant_did: Option<LocalDefId>,
995 ctor_did: Option<LocalDefId>,
997 discr: ty::VariantDiscr,
998 def: &hir::VariantData<'_>,
999 adt_kind: ty::AdtKind,
1000 parent_did: LocalDefId,
1001 ) -> ty::VariantDef {
1002 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
1007 let fid = tcx.hir().local_def_id(f.hir_id);
1008 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
1009 if let Some(prev_span) = dup_span {
1010 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
1011 field_name: f.ident,
1016 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
1019 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
1022 let recovered = match def {
1023 hir::VariantData::Struct(_, r) => *r,
1026 ty::VariantDef::new(
1028 variant_did.map(LocalDefId::to_def_id),
1029 ctor_did.map(LocalDefId::to_def_id),
1032 CtorKind::from_hir(def),
1034 parent_did.to_def_id(),
1036 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1037 || variant_did.map_or(false, |variant_did| {
1038 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1043 fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
1046 let def_id = def_id.expect_local();
1047 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1048 let Node::Item(item) = tcx.hir().get(hir_id) else {
1052 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1053 let (kind, variants) = match item.kind {
1054 ItemKind::Enum(ref def, _) => {
1055 let mut distance_from_explicit = 0;
1060 let variant_did = Some(tcx.hir().local_def_id(v.id));
1062 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1064 let discr = if let Some(ref e) = v.disr_expr {
1065 distance_from_explicit = 0;
1066 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1068 ty::VariantDiscr::Relative(distance_from_explicit)
1070 distance_from_explicit += 1;
1085 (AdtKind::Enum, variants)
1087 ItemKind::Struct(ref def, _) => {
1088 let variant_did = None::<LocalDefId>;
1089 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1091 let variants = std::iter::once(convert_variant(
1096 ty::VariantDiscr::Relative(0),
1103 (AdtKind::Struct, variants)
1105 ItemKind::Union(ref def, _) => {
1106 let variant_did = None;
1107 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1109 let variants = std::iter::once(convert_variant(
1114 ty::VariantDiscr::Relative(0),
1121 (AdtKind::Union, variants)
1125 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1128 /// Ensures that the super-predicates of the trait with a `DefId`
1129 /// of `trait_def_id` are converted and stored. This also ensures that
1130 /// the transitive super-predicates are converted.
1131 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1132 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1133 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1136 /// Ensures that the super-predicates of the trait with a `DefId`
1137 /// of `trait_def_id` are converted and stored. This also ensures that
1138 /// the transitive super-predicates are converted.
1139 fn super_predicates_that_define_assoc_type(
1141 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1142 ) -> ty::GenericPredicates<'_> {
1144 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1145 trait_def_id, assoc_name
1147 if trait_def_id.is_local() {
1148 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1149 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1151 let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
1152 bug!("trait_node_id {} is not an item", trait_hir_id);
1155 let (generics, bounds) = match item.kind {
1156 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1157 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1158 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1161 let icx = ItemCtxt::new(tcx, trait_def_id);
1163 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1164 let self_param_ty = tcx.types.self_param;
1165 let superbounds1 = if let Some(assoc_name) = assoc_name {
1166 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1173 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1176 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1178 // Convert any explicit superbounds in the where-clause,
1179 // e.g., `trait Foo where Self: Bar`.
1180 // In the case of trait aliases, however, we include all bounds in the where-clause,
1181 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1182 // as one of its "superpredicates".
1183 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1184 let superbounds2 = icx.type_parameter_bounds_in_generics(
1188 OnlySelfBounds(!is_trait_alias),
1192 // Combine the two lists to form the complete set of superbounds:
1193 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1195 // Now require that immediate supertraits are converted,
1196 // which will, in turn, reach indirect supertraits.
1197 if assoc_name.is_none() {
1198 // Now require that immediate supertraits are converted,
1199 // which will, in turn, reach indirect supertraits.
1200 for &(pred, span) in superbounds {
1201 debug!("superbound: {:?}", pred);
1202 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1203 tcx.at(span).super_predicates_of(bound.def_id());
1208 ty::GenericPredicates { parent: None, predicates: superbounds }
1210 // if `assoc_name` is None, then the query should've been redirected to an
1211 // external provider
1212 assert!(assoc_name.is_some());
1213 tcx.super_predicates_of(trait_def_id)
1217 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1218 let item = tcx.hir().expect_item(def_id.expect_local());
1220 let (is_auto, unsafety, items) = match item.kind {
1221 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1222 (is_auto == hir::IsAuto::Yes, unsafety, items)
1224 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1225 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1228 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1229 if paren_sugar && !tcx.features().unboxed_closures {
1233 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1234 which traits can use parenthetical notation",
1236 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1240 let is_marker = tcx.has_attr(def_id, sym::marker);
1241 let skip_array_during_method_dispatch =
1242 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1243 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1244 ty::trait_def::TraitSpecializationKind::Marker
1245 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1246 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1248 ty::trait_def::TraitSpecializationKind::None
1250 let must_implement_one_of = tcx
1253 .find(|attr| attr.has_name(sym::rustc_must_implement_one_of))
1254 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1255 // and that they are all identifiers
1256 .and_then(|attr| match attr.meta_item_list() {
1257 Some(items) if items.len() < 2 => {
1261 "the `#[rustc_must_implement_one_of]` attribute must be \
1262 used with at least 2 args",
1268 Some(items) => items
1270 .map(|item| item.ident().ok_or(item.span()))
1271 .collect::<Result<Box<[_]>, _>>()
1274 .struct_span_err(span, "must be a name of an associated function")
1278 .zip(Some(attr.span)),
1279 // Error is reported by `rustc_attr!`
1282 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1283 // functions in the trait with default implementations
1284 .and_then(|(list, attr_span)| {
1285 let errors = list.iter().filter_map(|ident| {
1286 let item = items.iter().find(|item| item.ident == *ident);
1289 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1290 if !item.defaultness.has_value() {
1294 "This function doesn't have a default implementation",
1296 .span_note(attr_span, "required by this annotation")
1306 .struct_span_err(item.span, "Not a function")
1307 .span_note(attr_span, "required by this annotation")
1309 "All `#[rustc_must_implement_one_of]` arguments \
1310 must be associated function names",
1316 .struct_span_err(ident.span, "Function not found in this trait")
1324 (errors.count() == 0).then_some(list)
1326 // Check for duplicates
1328 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1329 let mut no_dups = true;
1331 for ident in &*list {
1332 if let Some(dup) = set.insert(ident.name, ident.span) {
1334 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1336 "All `#[rustc_must_implement_one_of]` arguments \
1345 no_dups.then_some(list)
1354 skip_array_during_method_dispatch,
1356 must_implement_one_of,
1360 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1361 struct LateBoundRegionsDetector<'tcx> {
1363 outer_index: ty::DebruijnIndex,
1364 has_late_bound_regions: Option<Span>,
1367 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1368 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1369 if self.has_late_bound_regions.is_some() {
1373 hir::TyKind::BareFn(..) => {
1374 self.outer_index.shift_in(1);
1375 intravisit::walk_ty(self, ty);
1376 self.outer_index.shift_out(1);
1378 _ => intravisit::walk_ty(self, ty),
1382 fn visit_poly_trait_ref(
1384 tr: &'tcx hir::PolyTraitRef<'tcx>,
1385 m: hir::TraitBoundModifier,
1387 if self.has_late_bound_regions.is_some() {
1390 self.outer_index.shift_in(1);
1391 intravisit::walk_poly_trait_ref(self, tr, m);
1392 self.outer_index.shift_out(1);
1395 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1396 if self.has_late_bound_regions.is_some() {
1400 match self.tcx.named_region(lt.hir_id) {
1401 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1403 rl::Region::LateBound(debruijn, _, _)
1404 | rl::Region::LateBoundAnon(debruijn, _, _),
1405 ) if debruijn < self.outer_index => {}
1407 rl::Region::LateBound(..)
1408 | rl::Region::LateBoundAnon(..)
1409 | rl::Region::Free(..),
1412 self.has_late_bound_regions = Some(lt.span);
1418 fn has_late_bound_regions<'tcx>(
1421 generics: &'tcx hir::Generics<'tcx>,
1422 decl: &'tcx hir::FnDecl<'tcx>,
1424 let mut visitor = LateBoundRegionsDetector {
1426 outer_index: ty::INNERMOST,
1427 has_late_bound_regions: None,
1429 let late_bound_map = tcx.is_late_bound_map(def_id);
1430 let is_late_bound = |id| {
1431 let id = tcx.hir().local_def_id(id);
1432 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
1434 for param in generics.params {
1435 if let GenericParamKind::Lifetime { .. } = param.kind {
1436 if is_late_bound(param.hir_id) {
1437 return Some(param.span);
1441 visitor.visit_fn_decl(decl);
1442 visitor.has_late_bound_regions
1446 Node::TraitItem(item) => match item.kind {
1447 hir::TraitItemKind::Fn(ref sig, _) => {
1448 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1452 Node::ImplItem(item) => match item.kind {
1453 hir::ImplItemKind::Fn(ref sig, _) => {
1454 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1458 Node::ForeignItem(item) => match item.kind {
1459 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1460 has_late_bound_regions(tcx, item.def_id, generics, fn_decl)
1464 Node::Item(item) => match item.kind {
1465 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1466 has_late_bound_regions(tcx, item.def_id, generics, sig.decl)
1474 struct AnonConstInParamTyDetector {
1476 found_anon_const_in_param_ty: bool,
1480 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1481 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1482 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1483 let prev = self.in_param_ty;
1484 self.in_param_ty = true;
1486 self.in_param_ty = prev;
1490 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1491 if self.in_param_ty && self.ct == c.hir_id {
1492 self.found_anon_const_in_param_ty = true;
1494 intravisit::walk_anon_const(self, c)
1499 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1502 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1504 let node = tcx.hir().get(hir_id);
1505 let parent_def_id = match node {
1507 | Node::TraitItem(_)
1510 | Node::Field(_) => {
1511 let parent_id = tcx.hir().get_parent_item(hir_id);
1512 Some(parent_id.to_def_id())
1514 // FIXME(#43408) always enable this once `lazy_normalization` is
1515 // stable enough and does not need a feature gate anymore.
1516 Node::AnonConst(_) => {
1517 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1519 let mut in_param_ty = false;
1520 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1521 if let Some(generics) = node.generics() {
1522 let mut visitor = AnonConstInParamTyDetector {
1524 found_anon_const_in_param_ty: false,
1528 visitor.visit_generics(generics);
1529 in_param_ty = visitor.found_anon_const_in_param_ty;
1535 // We do not allow generic parameters in anon consts if we are inside
1536 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1538 } else if tcx.lazy_normalization() {
1539 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1540 // If the def_id we are calling generics_of on is an anon ct default i.e:
1542 // struct Foo<const N: usize = { .. }>;
1543 // ^^^ ^ ^^^^^^ def id of this anon const
1547 // then we only want to return generics for params to the left of `N`. If we don't do that we
1548 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1550 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1551 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1552 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1554 // We fix this by having this function return the parent's generics ourselves and truncating the
1555 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1557 // For the above code example that means we want `substs: []`
1558 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1559 // the def id of the `{ N + 1 }` anon const
1560 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1562 // This has some implications for how we get the predicates available to the anon const
1563 // see `explicit_predicates_of` for more information on this
1564 let generics = tcx.generics_of(parent_def_id.to_def_id());
1565 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1566 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1567 // In the above example this would be .params[..N#0]
1568 let params = generics.params[..param_def_idx as usize].to_owned();
1569 let param_def_id_to_index =
1570 params.iter().map(|param| (param.def_id, param.index)).collect();
1572 return ty::Generics {
1573 // we set the parent of these generics to be our parent's parent so that we
1574 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1575 // struct Foo<const N: usize, const M: usize = { ... }>;
1576 parent: generics.parent,
1577 parent_count: generics.parent_count,
1579 param_def_id_to_index,
1580 has_self: generics.has_self,
1581 has_late_bound_regions: generics.has_late_bound_regions,
1585 // HACK(eddyb) this provides the correct generics when
1586 // `feature(generic_const_expressions)` is enabled, so that const expressions
1587 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1589 // Note that we do not supply the parent generics when using
1590 // `min_const_generics`.
1591 Some(parent_def_id.to_def_id())
1593 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1595 // HACK(eddyb) this provides the correct generics for repeat
1596 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1597 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1598 // as they shouldn't be able to cause query cycle errors.
1599 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1600 if constant.hir_id() == hir_id =>
1602 Some(parent_def_id.to_def_id())
1604 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1605 if constant.hir_id == hir_id =>
1607 Some(parent_def_id.to_def_id())
1609 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1610 Some(tcx.typeck_root_def_id(def_id))
1616 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1617 Some(tcx.typeck_root_def_id(def_id))
1619 Node::Item(item) => match item.kind {
1620 ItemKind::OpaqueTy(hir::OpaqueTy {
1622 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1624 }) => Some(fn_def_id.to_def_id()),
1625 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1626 let parent_id = tcx.hir().get_parent_item(hir_id);
1627 assert_ne!(parent_id, CRATE_DEF_ID);
1628 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1629 // Opaque types are always nested within another item, and
1630 // inherit the generics of the item.
1631 Some(parent_id.to_def_id())
1638 let mut opt_self = None;
1639 let mut allow_defaults = false;
1641 let no_generics = hir::Generics::empty();
1642 let ast_generics = match node {
1643 Node::TraitItem(item) => &item.generics,
1645 Node::ImplItem(item) => &item.generics,
1647 Node::Item(item) => {
1649 ItemKind::Fn(.., ref generics, _)
1650 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1652 ItemKind::TyAlias(_, ref generics)
1653 | ItemKind::Enum(_, ref generics)
1654 | ItemKind::Struct(_, ref generics)
1655 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1656 | ItemKind::Union(_, ref generics) => {
1657 allow_defaults = true;
1661 ItemKind::Trait(_, _, ref generics, ..)
1662 | ItemKind::TraitAlias(ref generics, ..) => {
1663 // Add in the self type parameter.
1665 // Something of a hack: use the node id for the trait, also as
1666 // the node id for the Self type parameter.
1667 let param_id = item.def_id;
1669 opt_self = Some(ty::GenericParamDef {
1671 name: kw::SelfUpper,
1672 def_id: param_id.to_def_id(),
1673 pure_wrt_drop: false,
1674 kind: ty::GenericParamDefKind::Type {
1676 object_lifetime_default: rl::Set1::Empty,
1681 allow_defaults = true;
1689 Node::ForeignItem(item) => match item.kind {
1690 ForeignItemKind::Static(..) => &no_generics,
1691 ForeignItemKind::Fn(_, _, ref generics) => generics,
1692 ForeignItemKind::Type => &no_generics,
1698 let has_self = opt_self.is_some();
1699 let mut parent_has_self = false;
1700 let mut own_start = has_self as u32;
1701 let parent_count = parent_def_id.map_or(0, |def_id| {
1702 let generics = tcx.generics_of(def_id);
1704 parent_has_self = generics.has_self;
1705 own_start = generics.count() as u32;
1706 generics.parent_count + generics.params.len()
1709 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1711 if let Some(opt_self) = opt_self {
1712 params.push(opt_self);
1715 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics);
1716 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1717 name: param.name.ident().name,
1718 index: own_start + i as u32,
1719 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1720 pure_wrt_drop: param.pure_wrt_drop,
1721 kind: ty::GenericParamDefKind::Lifetime,
1724 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id.owner);
1726 // Now create the real type and const parameters.
1727 let type_start = own_start - has_self as u32 + params.len() as u32;
1730 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1731 GenericParamKind::Lifetime { .. } => None,
1732 GenericParamKind::Type { ref default, synthetic, .. } => {
1733 if !allow_defaults && default.is_some() {
1734 if !tcx.features().default_type_parameter_fallback {
1735 tcx.struct_span_lint_hir(
1736 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1741 "defaults for type parameters are only allowed in \
1742 `struct`, `enum`, `type`, or `trait` definitions",
1750 let kind = ty::GenericParamDefKind::Type {
1751 has_default: default.is_some(),
1752 object_lifetime_default: object_lifetime_defaults
1754 .map_or(rl::Set1::Empty, |o| o[i]),
1758 let param_def = ty::GenericParamDef {
1759 index: type_start + i as u32,
1760 name: param.name.ident().name,
1761 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1762 pure_wrt_drop: param.pure_wrt_drop,
1768 GenericParamKind::Const { default, .. } => {
1769 if !allow_defaults && default.is_some() {
1772 "defaults for const parameters are only allowed in \
1773 `struct`, `enum`, `type`, or `trait` definitions",
1777 let param_def = ty::GenericParamDef {
1778 index: type_start + i as u32,
1779 name: param.name.ident().name,
1780 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1781 pure_wrt_drop: param.pure_wrt_drop,
1782 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1789 // provide junk type parameter defs - the only place that
1790 // cares about anything but the length is instantiation,
1791 // and we don't do that for closures.
1792 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1793 let dummy_args = if gen.is_some() {
1794 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1796 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1799 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1800 index: type_start + i as u32,
1801 name: Symbol::intern(arg),
1803 pure_wrt_drop: false,
1804 kind: ty::GenericParamDefKind::Type {
1806 object_lifetime_default: rl::Set1::Empty,
1812 // provide junk type parameter defs for const blocks.
1813 if let Node::AnonConst(_) = node {
1814 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1815 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1816 params.push(ty::GenericParamDef {
1818 name: Symbol::intern("<const_ty>"),
1820 pure_wrt_drop: false,
1821 kind: ty::GenericParamDefKind::Type {
1823 object_lifetime_default: rl::Set1::Empty,
1830 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1833 parent: parent_def_id,
1836 param_def_id_to_index,
1837 has_self: has_self || parent_has_self,
1838 has_late_bound_regions: has_late_bound_regions(tcx, node),
1842 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1843 generic_args.iter().any(|arg| match arg {
1844 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1845 hir::GenericArg::Infer(_) => true,
1850 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1851 /// use inference to provide suggestions for the appropriate type if possible.
1852 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1857 Slice(ty) => is_suggestable_infer_ty(ty),
1858 Array(ty, length) => {
1859 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1861 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1862 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1863 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1864 Path(hir::QPath::TypeRelative(ty, segment)) => {
1865 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1867 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1868 ty_opt.map_or(false, is_suggestable_infer_ty)
1869 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1875 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1876 if let hir::FnRetTy::Return(ty) = output {
1877 if is_suggestable_infer_ty(ty) {
1884 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1885 use rustc_hir::Node::*;
1888 let def_id = def_id.expect_local();
1889 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1891 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1893 match tcx.hir().get(hir_id) {
1894 TraitItem(hir::TraitItem {
1895 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1900 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1901 infer_return_ty_for_fn_sig(tcx, sig, *ident, generics, def_id, &icx)
1904 ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. }) => {
1905 // Do not try to inference the return type for a impl method coming from a trait
1906 if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) =
1907 tcx.hir().get(tcx.hir().get_parent_node(hir_id))
1908 && i.of_trait.is_some()
1910 <dyn AstConv<'_>>::ty_of_fn(
1913 sig.header.unsafety,
1921 infer_return_ty_for_fn_sig(tcx, sig, *ident, generics, def_id, &icx)
1925 TraitItem(hir::TraitItem {
1926 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1930 }) => <dyn AstConv<'_>>::ty_of_fn(
1941 ForeignItem(&hir::ForeignItem {
1942 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1944 let abi = tcx.hir().get_foreign_abi(hir_id);
1945 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1948 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1949 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1951 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1952 ty::Binder::dummy(tcx.mk_fn_sig(
1956 hir::Unsafety::Normal,
1961 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1962 // Closure signatures are not like other function
1963 // signatures and cannot be accessed through `fn_sig`. For
1964 // example, a closure signature excludes the `self`
1965 // argument. In any case they are embedded within the
1966 // closure type as part of the `ClosureSubsts`.
1968 // To get the signature of a closure, you should use the
1969 // `sig` method on the `ClosureSubsts`:
1971 // substs.as_closure().sig(def_id, tcx)
1973 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1978 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1983 fn infer_return_ty_for_fn_sig<'tcx>(
1985 sig: &hir::FnSig<'_>,
1987 generics: &hir::Generics<'_>,
1989 icx: &ItemCtxt<'tcx>,
1990 ) -> ty::PolyFnSig<'tcx> {
1991 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1993 match get_infer_ret_ty(&sig.decl.output) {
1995 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1996 // Typeck doesn't expect erased regions to be returned from `type_of`.
1997 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match *r {
1998 ty::ReErased => tcx.lifetimes.re_static,
2001 let fn_sig = ty::Binder::dummy(fn_sig);
2003 let mut visitor = HirPlaceholderCollector::default();
2004 visitor.visit_ty(ty);
2005 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
2006 let ret_ty = fn_sig.skip_binder().output();
2007 if ret_ty.is_suggestable(tcx) {
2008 diag.span_suggestion(
2010 "replace with the correct return type",
2012 Applicability::MachineApplicable,
2014 } else if matches!(ret_ty.kind(), ty::FnDef(..)) {
2015 let fn_sig = ret_ty.fn_sig(tcx);
2016 if fn_sig.skip_binder().inputs_and_output.iter().all(|t| t.is_suggestable(tcx)) {
2017 diag.span_suggestion(
2019 "replace with the correct return type",
2021 Applicability::MachineApplicable,
2024 } else if ret_ty.is_closure() {
2025 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
2026 // to prevent the user from getting a papercut while trying to use the unique closure
2027 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
2028 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
2029 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
2035 None => <dyn AstConv<'_>>::ty_of_fn(
2038 sig.header.unsafety,
2048 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
2049 let icx = ItemCtxt::new(tcx, def_id);
2050 match tcx.hir().expect_item(def_id.expect_local()).kind {
2051 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
2052 let selfty = tcx.type_of(def_id);
2053 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
2059 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
2060 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
2061 let item = tcx.hir().expect_item(def_id.expect_local());
2063 hir::ItemKind::Impl(hir::Impl {
2064 polarity: hir::ImplPolarity::Negative(span),
2068 if is_rustc_reservation {
2069 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
2070 tcx.sess.span_err(span, "reservation impls can't be negative");
2072 ty::ImplPolarity::Negative
2074 hir::ItemKind::Impl(hir::Impl {
2075 polarity: hir::ImplPolarity::Positive,
2079 if is_rustc_reservation {
2080 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2082 ty::ImplPolarity::Positive
2084 hir::ItemKind::Impl(hir::Impl {
2085 polarity: hir::ImplPolarity::Positive,
2089 if is_rustc_reservation {
2090 ty::ImplPolarity::Reservation
2092 ty::ImplPolarity::Positive
2095 item => bug!("impl_polarity: {:?} not an impl", item),
2099 /// Returns the early-bound lifetimes declared in this generics
2100 /// listing. For anything other than fns/methods, this is just all
2101 /// the lifetimes that are declared. For fns or methods, we have to
2102 /// screen out those that do not appear in any where-clauses etc using
2103 /// `resolve_lifetime::early_bound_lifetimes`.
2104 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2107 generics: &'a hir::Generics<'a>,
2108 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2109 let late_bound_map = if generics.params.is_empty() {
2110 // This function may be called on `def_id == CRATE_DEF_ID`,
2111 // which makes `is_late_bound_map` ICE. Don't even try if there
2112 // is no generic parameter.
2115 tcx.is_late_bound_map(def_id)
2117 let is_late_bound = move |hir_id| {
2118 let id = tcx.hir().local_def_id(hir_id);
2119 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
2121 generics.params.iter().filter(move |param| match param.kind {
2122 GenericParamKind::Lifetime { .. } => !is_late_bound(param.hir_id),
2127 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2128 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2129 /// inferred constraints concerning which regions outlive other regions.
2130 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2131 debug!("predicates_defined_on({:?})", def_id);
2132 let mut result = tcx.explicit_predicates_of(def_id);
2133 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2134 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2135 if !inferred_outlives.is_empty() {
2137 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2138 def_id, inferred_outlives,
2140 if result.predicates.is_empty() {
2141 result.predicates = inferred_outlives;
2143 result.predicates = tcx
2145 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2149 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2153 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2154 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2155 /// `Self: Trait` predicates for traits.
2156 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2157 let mut result = tcx.predicates_defined_on(def_id);
2159 if tcx.is_trait(def_id) {
2160 // For traits, add `Self: Trait` predicate. This is
2161 // not part of the predicates that a user writes, but it
2162 // is something that one must prove in order to invoke a
2163 // method or project an associated type.
2165 // In the chalk setup, this predicate is not part of the
2166 // "predicates" for a trait item. But it is useful in
2167 // rustc because if you directly (e.g.) invoke a trait
2168 // method like `Trait::method(...)`, you must naturally
2169 // prove that the trait applies to the types that were
2170 // used, and adding the predicate into this list ensures
2171 // that this is done.
2173 // We use a DUMMY_SP here as a way to signal trait bounds that come
2174 // from the trait itself that *shouldn't* be shown as the source of
2175 // an obligation and instead be skipped. Otherwise we'd use
2176 // `tcx.def_span(def_id);`
2177 let span = rustc_span::DUMMY_SP;
2179 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2180 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2184 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2188 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2189 /// N.B., this does not include any implied/inferred constraints.
2190 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2193 debug!("explicit_predicates_of(def_id={:?})", def_id);
2195 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2196 let node = tcx.hir().get(hir_id);
2198 let mut is_trait = None;
2199 let mut is_default_impl_trait = None;
2201 let icx = ItemCtxt::new(tcx, def_id);
2203 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2205 // We use an `IndexSet` to preserves order of insertion.
2206 // Preserving the order of insertion is important here so as not to break UI tests.
2207 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2209 let ast_generics = match node {
2210 Node::TraitItem(item) => &item.generics,
2212 Node::ImplItem(item) => &item.generics,
2214 Node::Item(item) => {
2216 ItemKind::Impl(ref impl_) => {
2217 if impl_.defaultness.is_default() {
2218 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2222 ItemKind::Fn(.., ref generics, _)
2223 | ItemKind::TyAlias(_, ref generics)
2224 | ItemKind::Enum(_, ref generics)
2225 | ItemKind::Struct(_, ref generics)
2226 | ItemKind::Union(_, ref generics) => generics,
2228 ItemKind::Trait(_, _, ref generics, ..) => {
2229 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2232 ItemKind::TraitAlias(ref generics, _) => {
2233 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2236 ItemKind::OpaqueTy(OpaqueTy {
2237 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2240 // return-position impl trait
2242 // We don't inherit predicates from the parent here:
2243 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2244 // then the return type is `f::<'static, T>::{{opaque}}`.
2246 // If we inherited the predicates of `f` then we would
2247 // require that `T: 'static` to show that the return
2248 // type is well-formed.
2250 // The only way to have something with this opaque type
2251 // is from the return type of the containing function,
2252 // which will ensure that the function's predicates
2254 return ty::GenericPredicates { parent: None, predicates: &[] };
2256 ItemKind::OpaqueTy(OpaqueTy {
2258 origin: hir::OpaqueTyOrigin::TyAlias,
2261 // type-alias impl trait
2269 Node::ForeignItem(item) => match item.kind {
2270 ForeignItemKind::Static(..) => NO_GENERICS,
2271 ForeignItemKind::Fn(_, _, ref generics) => generics,
2272 ForeignItemKind::Type => NO_GENERICS,
2278 let generics = tcx.generics_of(def_id);
2279 let parent_count = generics.parent_count as u32;
2280 let has_own_self = generics.has_self && parent_count == 0;
2282 // Below we'll consider the bounds on the type parameters (including `Self`)
2283 // and the explicit where-clauses, but to get the full set of predicates
2284 // on a trait we need to add in the supertrait bounds and bounds found on
2285 // associated types.
2286 if let Some(_trait_ref) = is_trait {
2287 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2290 // In default impls, we can assume that the self type implements
2291 // the trait. So in:
2293 // default impl Foo for Bar { .. }
2295 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2296 // (see below). Recall that a default impl is not itself an impl, but rather a
2297 // set of defaults that can be incorporated into another impl.
2298 if let Some(trait_ref) = is_default_impl_trait {
2299 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2302 // Collect the region predicates that were declared inline as
2303 // well. In the case of parameters declared on a fn or method, we
2304 // have to be careful to only iterate over early-bound regions.
2305 let mut index = parent_count + has_own_self as u32;
2306 for param in early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics) {
2307 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2308 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2310 name: param.name.ident().name,
2315 GenericParamKind::Lifetime { .. } => {
2316 param.bounds.iter().for_each(|bound| match bound {
2317 hir::GenericBound::Outlives(lt) => {
2318 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2319 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2320 predicates.insert((outlives.to_predicate(tcx), lt.span));
2329 // Collect the predicates that were written inline by the user on each
2330 // type parameter (e.g., `<T: Foo>`).
2331 for param in ast_generics.params {
2333 // We already dealt with early bound lifetimes above.
2334 GenericParamKind::Lifetime { .. } => (),
2335 GenericParamKind::Type { .. } => {
2336 let name = param.name.ident().name;
2337 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2340 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2341 // Params are implicitly sized unless a `?Sized` bound is found
2342 <dyn AstConv<'_>>::add_implicitly_sized(
2346 Some((param.hir_id, ast_generics.where_clause.predicates)),
2349 predicates.extend(bounds.predicates(tcx, param_ty));
2351 GenericParamKind::Const { .. } => {
2352 // Bounds on const parameters are currently not possible.
2353 debug_assert!(param.bounds.is_empty());
2359 // Add in the bounds that appear in the where-clause.
2360 let where_clause = &ast_generics.where_clause;
2361 for predicate in where_clause.predicates {
2363 hir::WherePredicate::BoundPredicate(bound_pred) => {
2364 let ty = icx.to_ty(bound_pred.bounded_ty);
2365 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2367 // Keep the type around in a dummy predicate, in case of no bounds.
2368 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2369 // is still checked for WF.
2370 if bound_pred.bounds.is_empty() {
2371 if let ty::Param(_) = ty.kind() {
2372 // This is a `where T:`, which can be in the HIR from the
2373 // transformation that moves `?Sized` to `T`'s declaration.
2374 // We can skip the predicate because type parameters are
2375 // trivially WF, but also we *should*, to avoid exposing
2376 // users who never wrote `where Type:,` themselves, to
2377 // compiler/tooling bugs from not handling WF predicates.
2379 let span = bound_pred.bounded_ty.span;
2380 let re_root_empty = tcx.lifetimes.re_root_empty;
2381 let predicate = ty::Binder::bind_with_vars(
2382 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2388 predicates.insert((predicate.to_predicate(tcx), span));
2392 let mut bounds = Bounds::default();
2393 <dyn AstConv<'_>>::add_bounds(
2396 bound_pred.bounds.iter(),
2400 predicates.extend(bounds.predicates(tcx, ty));
2403 hir::WherePredicate::RegionPredicate(region_pred) => {
2404 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2405 predicates.extend(region_pred.bounds.iter().map(|bound| {
2406 let (r2, span) = match bound {
2407 hir::GenericBound::Outlives(lt) => {
2408 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2412 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2413 ty::OutlivesPredicate(r1, r2),
2415 .to_predicate(icx.tcx);
2421 hir::WherePredicate::EqPredicate(..) => {
2427 if tcx.features().generic_const_exprs {
2428 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2431 let mut predicates: Vec<_> = predicates.into_iter().collect();
2433 // Subtle: before we store the predicates into the tcx, we
2434 // sort them so that predicates like `T: Foo<Item=U>` come
2435 // before uses of `U`. This avoids false ambiguity errors
2436 // in trait checking. See `setup_constraining_predicates`
2438 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2439 let self_ty = tcx.type_of(def_id);
2440 let trait_ref = tcx.impl_trait_ref(def_id);
2441 cgp::setup_constraining_predicates(
2445 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2449 let result = ty::GenericPredicates {
2450 parent: generics.parent,
2451 predicates: tcx.arena.alloc_from_iter(predicates),
2453 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2457 fn const_evaluatable_predicates_of<'tcx>(
2460 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2461 struct ConstCollector<'tcx> {
2463 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2466 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2467 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2468 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2469 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2470 if let ty::ConstKind::Unevaluated(uv) = ct.val() {
2471 assert_eq!(uv.promoted, None);
2472 let span = self.tcx.hir().span(c.hir_id);
2474 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2475 .to_predicate(self.tcx),
2481 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2482 // Do not look into const param defaults,
2483 // these get checked when they are actually instantiated.
2485 // We do not want the following to error:
2487 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2488 // struct Bar<const N: usize>(Foo<N, 3>);
2492 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2493 let node = tcx.hir().get(hir_id);
2495 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2496 if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
2497 if let Some(of_trait) = &impl_.of_trait {
2498 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2499 collector.visit_trait_ref(of_trait);
2502 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2503 collector.visit_ty(impl_.self_ty);
2506 if let Some(generics) = node.generics() {
2507 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2508 collector.visit_generics(generics);
2511 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2512 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2513 collector.visit_fn_decl(fn_sig.decl);
2515 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2520 fn trait_explicit_predicates_and_bounds(
2523 ) -> ty::GenericPredicates<'_> {
2524 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2525 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2528 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2529 let def_kind = tcx.def_kind(def_id);
2530 if let DefKind::Trait = def_kind {
2531 // Remove bounds on associated types from the predicates, they will be
2532 // returned by `explicit_item_bounds`.
2533 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2534 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2536 let is_assoc_item_ty = |ty: Ty<'_>| {
2537 // For a predicate from a where clause to become a bound on an
2539 // * It must use the identity substs of the item.
2540 // * Since any generic parameters on the item are not in scope,
2541 // this means that the item is not a GAT, and its identity
2542 // substs are the same as the trait's.
2543 // * It must be an associated type for this trait (*not* a
2545 if let ty::Projection(projection) = ty.kind() {
2546 projection.substs == trait_identity_substs
2547 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2553 let predicates: Vec<_> = predicates_and_bounds
2557 .filter(|(pred, _)| match pred.kind().skip_binder() {
2558 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2559 ty::PredicateKind::Projection(proj) => {
2560 !is_assoc_item_ty(proj.projection_ty.self_ty())
2562 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2566 if predicates.len() == predicates_and_bounds.predicates.len() {
2567 predicates_and_bounds
2569 ty::GenericPredicates {
2570 parent: predicates_and_bounds.parent,
2571 predicates: tcx.arena.alloc_slice(&predicates),
2575 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2576 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2577 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2578 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2579 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2580 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2582 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2583 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2584 // ^^^ explicit_predicates_of on
2585 // parent item we dont have set as the
2586 // parent of generics returned by `generics_of`
2588 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2589 let item_def_id = tcx.hir().get_parent_item(hir_id);
2590 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2591 return tcx.explicit_predicates_of(item_def_id);
2594 gather_explicit_predicates_of(tcx, def_id)
2598 /// Converts a specific `GenericBound` from the AST into a set of
2599 /// predicates that apply to the self type. A vector is returned
2600 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2601 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2602 /// and `<T as Bar>::X == i32`).
2603 fn predicates_from_bound<'tcx>(
2604 astconv: &dyn AstConv<'tcx>,
2606 bound: &'tcx hir::GenericBound<'tcx>,
2607 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2608 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2609 let mut bounds = Bounds::default();
2610 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2611 bounds.predicates(astconv.tcx(), param_ty).collect()
2614 fn compute_sig_of_foreign_fn_decl<'tcx>(
2617 decl: &'tcx hir::FnDecl<'tcx>,
2620 ) -> ty::PolyFnSig<'tcx> {
2621 let unsafety = if abi == abi::Abi::RustIntrinsic {
2622 intrinsic_operation_unsafety(tcx.item_name(def_id))
2624 hir::Unsafety::Unsafe
2626 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2627 let fty = <dyn AstConv<'_>>::ty_of_fn(
2628 &ItemCtxt::new(tcx, def_id),
2633 &hir::Generics::empty(),
2638 // Feature gate SIMD types in FFI, since I am not sure that the
2639 // ABIs are handled at all correctly. -huonw
2640 if abi != abi::Abi::RustIntrinsic
2641 && abi != abi::Abi::PlatformIntrinsic
2642 && !tcx.features().simd_ffi
2644 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2649 .span_to_snippet(ast_ty.span)
2650 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2655 "use of SIMD type{} in FFI is highly experimental and \
2656 may result in invalid code",
2660 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2664 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2667 if let hir::FnRetTy::Return(ref ty) = decl.output {
2668 check(ty, fty.output().skip_binder())
2675 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2676 match tcx.hir().get_if_local(def_id) {
2677 Some(Node::ForeignItem(..)) => true,
2679 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2683 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2684 match tcx.hir().get_if_local(def_id) {
2685 Some(Node::Expr(&rustc_hir::Expr {
2686 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2688 })) => tcx.hir().body(body_id).generator_kind(),
2690 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2694 fn from_target_feature(
2697 attr: &ast::Attribute,
2698 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2699 target_features: &mut Vec<Symbol>,
2701 let Some(list) = attr.meta_item_list() else { return };
2702 let bad_item = |span| {
2703 let msg = "malformed `target_feature` attribute input";
2704 let code = "enable = \"..\"".to_owned();
2706 .struct_span_err(span, msg)
2707 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2710 let rust_features = tcx.features();
2712 // Only `enable = ...` is accepted in the meta-item list.
2713 if !item.has_name(sym::enable) {
2714 bad_item(item.span());
2718 // Must be of the form `enable = "..."` (a string).
2719 let Some(value) = item.value_str() else {
2720 bad_item(item.span());
2724 // We allow comma separation to enable multiple features.
2725 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2726 let Some(feature_gate) = supported_target_features.get(feature) else {
2728 format!("the feature named `{}` is not valid for this target", feature);
2729 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2732 format!("`{}` is not valid for this target", feature),
2734 if let Some(stripped) = feature.strip_prefix('+') {
2735 let valid = supported_target_features.contains_key(stripped);
2737 err.help("consider removing the leading `+` in the feature name");
2744 // Only allow features whose feature gates have been enabled.
2745 let allowed = match feature_gate.as_ref().copied() {
2746 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2747 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2748 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2749 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2750 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2751 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2752 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2753 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2754 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2755 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2756 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2757 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2758 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2759 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2760 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2761 Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
2762 Some(name) => bug!("unknown target feature gate {}", name),
2765 if !allowed && id.is_local() {
2767 &tcx.sess.parse_sess,
2768 feature_gate.unwrap(),
2770 &format!("the target feature `{}` is currently unstable", feature),
2774 Some(Symbol::intern(feature))
2779 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2780 use rustc_middle::mir::mono::Linkage::*;
2782 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2783 // applicable to variable declarations and may not really make sense for
2784 // Rust code in the first place but allow them anyway and trust that the
2785 // user knows what they're doing. Who knows, unanticipated use cases may pop
2786 // up in the future.
2788 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2789 // and don't have to be, LLVM treats them as no-ops.
2791 "appending" => Appending,
2792 "available_externally" => AvailableExternally,
2794 "extern_weak" => ExternalWeak,
2795 "external" => External,
2796 "internal" => Internal,
2797 "linkonce" => LinkOnceAny,
2798 "linkonce_odr" => LinkOnceODR,
2799 "private" => Private,
2801 "weak_odr" => WeakODR,
2803 let span = tcx.hir().span_if_local(def_id);
2804 if let Some(span) = span {
2805 tcx.sess.span_fatal(span, "invalid linkage specified")
2807 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2813 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2814 let attrs = tcx.get_attrs(id);
2816 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2817 if tcx.should_inherit_track_caller(id) {
2818 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2821 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2822 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2823 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2824 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2828 // The panic_no_unwind function called by TerminatorKind::Abort will never
2829 // unwind. If the panic handler that it invokes unwind then it will simply
2830 // call the panic handler again.
2831 if Some(id) == tcx.lang_items().panic_no_unwind() {
2832 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2835 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2837 let mut inline_span = None;
2838 let mut link_ordinal_span = None;
2839 let mut no_sanitize_span = None;
2840 for attr in attrs.iter() {
2841 if attr.has_name(sym::cold) {
2842 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2843 } else if attr.has_name(sym::rustc_allocator) {
2844 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2845 } else if attr.has_name(sym::ffi_returns_twice) {
2846 if tcx.is_foreign_item(id) {
2847 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2849 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2854 "`#[ffi_returns_twice]` may only be used on foreign functions"
2858 } else if attr.has_name(sym::ffi_pure) {
2859 if tcx.is_foreign_item(id) {
2860 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2861 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2866 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2870 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2873 // `#[ffi_pure]` is only allowed on foreign functions
2878 "`#[ffi_pure]` may only be used on foreign functions"
2882 } else if attr.has_name(sym::ffi_const) {
2883 if tcx.is_foreign_item(id) {
2884 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2886 // `#[ffi_const]` is only allowed on foreign functions
2891 "`#[ffi_const]` may only be used on foreign functions"
2895 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2896 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2897 } else if attr.has_name(sym::naked) {
2898 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2899 } else if attr.has_name(sym::no_mangle) {
2900 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2901 } else if attr.has_name(sym::no_coverage) {
2902 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2903 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2904 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2905 } else if attr.has_name(sym::used) {
2906 let inner = attr.meta_item_list();
2907 match inner.as_deref() {
2908 Some([item]) if item.has_name(sym::linker) => {
2909 if !tcx.features().used_with_arg {
2911 &tcx.sess.parse_sess,
2914 "`#[used(linker)]` is currently unstable",
2918 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2920 Some([item]) if item.has_name(sym::compiler) => {
2921 if !tcx.features().used_with_arg {
2923 &tcx.sess.parse_sess,
2926 "`#[used(compiler)]` is currently unstable",
2930 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2936 "expected `used`, `used(compiler)` or `used(linker)`",
2940 None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
2942 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2943 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2948 "`#[cmse_nonsecure_entry]` requires C ABI"
2952 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2953 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2956 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2957 } else if attr.has_name(sym::thread_local) {
2958 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2959 } else if attr.has_name(sym::track_caller) {
2960 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2961 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2964 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2966 &tcx.sess.parse_sess,
2967 sym::closure_track_caller,
2969 "`#[track_caller]` on closures is currently unstable",
2973 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2974 } else if attr.has_name(sym::export_name) {
2975 if let Some(s) = attr.value_str() {
2976 if s.as_str().contains('\0') {
2977 // `#[export_name = ...]` will be converted to a null-terminated string,
2978 // so it may not contain any null characters.
2983 "`export_name` may not contain null characters"
2987 codegen_fn_attrs.export_name = Some(s);
2989 } else if attr.has_name(sym::target_feature) {
2990 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2991 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2992 // The `#[target_feature]` attribute is allowed on
2993 // WebAssembly targets on all functions, including safe
2994 // ones. Other targets require that `#[target_feature]` is
2995 // only applied to unsafe functions (pending the
2996 // `target_feature_11` feature) because on most targets
2997 // execution of instructions that are not supported is
2998 // considered undefined behavior. For WebAssembly which is a
2999 // 100% safe target at execution time it's not possible to
3000 // execute undefined instructions, and even if a future
3001 // feature was added in some form for this it would be a
3002 // deterministic trap. There is no undefined behavior when
3003 // executing WebAssembly so `#[target_feature]` is allowed
3004 // on safe functions (but again, only for WebAssembly)
3006 // Note that this is also allowed if `actually_rustdoc` so
3007 // if a target is documenting some wasm-specific code then
3008 // it's not spuriously denied.
3009 } else if !tcx.features().target_feature_11 {
3010 let mut err = feature_err(
3011 &tcx.sess.parse_sess,
3012 sym::target_feature_11,
3014 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
3016 err.span_label(tcx.def_span(id), "not an `unsafe` function");
3018 } else if let Some(local_id) = id.as_local() {
3019 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
3022 from_target_feature(
3026 supported_target_features,
3027 &mut codegen_fn_attrs.target_features,
3029 } else if attr.has_name(sym::linkage) {
3030 if let Some(val) = attr.value_str() {
3031 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, val.as_str()));
3033 } else if attr.has_name(sym::link_section) {
3034 if let Some(val) = attr.value_str() {
3035 if val.as_str().bytes().any(|b| b == 0) {
3037 "illegal null byte in link_section \
3041 tcx.sess.span_err(attr.span, &msg);
3043 codegen_fn_attrs.link_section = Some(val);
3046 } else if attr.has_name(sym::link_name) {
3047 codegen_fn_attrs.link_name = attr.value_str();
3048 } else if attr.has_name(sym::link_ordinal) {
3049 link_ordinal_span = Some(attr.span);
3050 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
3051 codegen_fn_attrs.link_ordinal = ordinal;
3053 } else if attr.has_name(sym::no_sanitize) {
3054 no_sanitize_span = Some(attr.span);
3055 if let Some(list) = attr.meta_item_list() {
3056 for item in list.iter() {
3057 if item.has_name(sym::address) {
3058 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
3059 } else if item.has_name(sym::cfi) {
3060 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
3061 } else if item.has_name(sym::memory) {
3062 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
3063 } else if item.has_name(sym::memtag) {
3064 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
3065 } else if item.has_name(sym::thread) {
3066 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
3067 } else if item.has_name(sym::hwaddress) {
3068 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
3071 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
3072 .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, or `thread`")
3077 } else if attr.has_name(sym::instruction_set) {
3078 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
3079 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
3080 [NestedMetaItem::MetaItem(set)] => {
3082 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
3083 match segments.as_slice() {
3084 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3085 if !tcx.sess.target.has_thumb_interworking {
3087 tcx.sess.diagnostic(),
3090 "target does not support `#[instruction_set]`"
3094 } else if segments[1] == sym::a32 {
3095 Some(InstructionSetAttr::ArmA32)
3096 } else if segments[1] == sym::t32 {
3097 Some(InstructionSetAttr::ArmT32)
3104 tcx.sess.diagnostic(),
3107 "invalid instruction set specified",
3116 tcx.sess.diagnostic(),
3119 "`#[instruction_set]` requires an argument"
3126 tcx.sess.diagnostic(),
3129 "cannot specify more than one instruction set"
3137 tcx.sess.diagnostic(),
3140 "must specify an instruction set"
3146 } else if attr.has_name(sym::repr) {
3147 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3148 Some(items) => match items.as_slice() {
3149 [item] => match item.name_value_literal() {
3150 Some((sym::align, literal)) => {
3151 let alignment = rustc_attr::parse_alignment(&literal.kind);
3154 Ok(align) => Some(align),
3157 tcx.sess.diagnostic(),
3160 "invalid `repr(align)` attribute: {}",
3179 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3180 if !attr.has_name(sym::inline) {
3183 match attr.meta_kind() {
3184 Some(MetaItemKind::Word) => InlineAttr::Hint,
3185 Some(MetaItemKind::List(ref items)) => {
3186 inline_span = Some(attr.span);
3187 if items.len() != 1 {
3189 tcx.sess.diagnostic(),
3192 "expected one argument"
3196 } else if list_contains_name(&items, sym::always) {
3198 } else if list_contains_name(&items, sym::never) {
3202 tcx.sess.diagnostic(),
3212 Some(MetaItemKind::NameValue(_)) => ia,
3217 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3218 if !attr.has_name(sym::optimize) {
3221 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3222 match attr.meta_kind() {
3223 Some(MetaItemKind::Word) => {
3224 err(attr.span, "expected one argument");
3227 Some(MetaItemKind::List(ref items)) => {
3228 inline_span = Some(attr.span);
3229 if items.len() != 1 {
3230 err(attr.span, "expected one argument");
3232 } else if list_contains_name(&items, sym::size) {
3234 } else if list_contains_name(&items, sym::speed) {
3237 err(items[0].span(), "invalid argument");
3241 Some(MetaItemKind::NameValue(_)) => ia,
3246 // #73631: closures inherit `#[target_feature]` annotations
3247 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3248 let owner_id = tcx.parent(id).expect("closure should have a parent");
3251 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3254 // If a function uses #[target_feature] it can't be inlined into general
3255 // purpose functions as they wouldn't have the right target features
3256 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3258 if !codegen_fn_attrs.target_features.is_empty() {
3259 if codegen_fn_attrs.inline == InlineAttr::Always {
3260 if let Some(span) = inline_span {
3263 "cannot use `#[inline(always)]` with \
3264 `#[target_feature]`",
3270 if !codegen_fn_attrs.no_sanitize.is_empty() {
3271 if codegen_fn_attrs.inline == InlineAttr::Always {
3272 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3273 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3274 tcx.struct_span_lint_hir(
3275 lint::builtin::INLINE_NO_SANITIZE,
3279 lint.build("`no_sanitize` will have no effect after inlining")
3280 .span_note(inline_span, "inlining requested here")
3288 // Weak lang items have the same semantics as "std internal" symbols in the
3289 // sense that they're preserved through all our LTO passes and only
3290 // strippable by the linker.
3292 // Additionally weak lang items have predetermined symbol names.
3293 if tcx.is_weak_lang_item(id) {
3294 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3296 if let Some(name) = weak_lang_items::link_name(attrs) {
3297 codegen_fn_attrs.export_name = Some(name);
3298 codegen_fn_attrs.link_name = Some(name);
3300 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3302 // Internal symbols to the standard library all have no_mangle semantics in
3303 // that they have defined symbol names present in the function name. This
3304 // also applies to weak symbols where they all have known symbol names.
3305 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3306 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3309 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3310 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3311 // intrinsic functions.
3312 if let Some(name) = &codegen_fn_attrs.link_name {
3313 if name.as_str().starts_with("llvm.") {
3314 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3321 /// Computes the set of target features used in a function for the purposes of
3322 /// inline assembly.
3323 fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, id: DefId) -> &'tcx FxHashSet<Symbol> {
3324 let mut target_features = tcx.sess.target_features.clone();
3325 let attrs = tcx.codegen_fn_attrs(id);
3326 target_features.extend(&attrs.target_features);
3327 match attrs.instruction_set {
3329 Some(InstructionSetAttr::ArmA32) => {
3330 target_features.remove(&sym::thumb_mode);
3332 Some(InstructionSetAttr::ArmT32) => {
3333 target_features.insert(sym::thumb_mode);
3336 tcx.arena.alloc(target_features)
3339 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3340 /// applied to the method prototype.
3341 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3342 if let Some(impl_item) = tcx.opt_associated_item(def_id)
3343 && let ty::AssocItemContainer::ImplContainer(_) = impl_item.container
3344 && let Some(trait_item) = impl_item.trait_item_def_id
3347 .codegen_fn_attrs(trait_item)
3349 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3355 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3356 use rustc_ast::{Lit, LitIntType, LitKind};
3357 let meta_item_list = attr.meta_item_list();
3358 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3359 let sole_meta_list = match meta_item_list {
3360 Some([item]) => item.literal(),
3363 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3364 .note("the attribute requires exactly one argument")
3370 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3371 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3372 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3373 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3374 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3376 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3377 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3378 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3379 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3380 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3381 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3382 // about LINK.EXE failing.)
3383 if *ordinal <= u16::MAX as u128 {
3384 Some(*ordinal as u16)
3386 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3388 .struct_span_err(attr.span, &msg)
3389 .note("the value may not exceed `u16::MAX`")
3395 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3396 .note("an unsuffixed integer value, e.g., `1`, is expected")
3402 fn check_link_name_xor_ordinal(
3404 codegen_fn_attrs: &CodegenFnAttrs,
3405 inline_span: Option<Span>,
3407 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3410 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3411 if let Some(span) = inline_span {
3412 tcx.sess.span_err(span, msg);
3418 /// Checks the function annotated with `#[target_feature]` is not a safe
3419 /// trait method implementation, reporting an error if it is.
3420 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3421 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3422 let node = tcx.hir().get(hir_id);
3423 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3424 let parent_id = tcx.hir().get_parent_item(hir_id);
3425 let parent_item = tcx.hir().expect_item(parent_id);
3426 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3430 "`#[target_feature(..)]` cannot be applied to safe trait method",
3432 .span_label(attr_span, "cannot be applied to safe trait method")
3433 .span_label(tcx.def_span(id), "not an `unsafe` function")