1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::AstConv;
18 use crate::bounds::Bounds;
19 use crate::check::intrinsic::intrinsic_operation_unsafety;
20 use crate::constrained_generic_params as cgp;
22 use crate::middle::resolve_lifetime as rl;
24 use rustc_ast::{MetaItemKind, NestedMetaItem};
25 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
26 use rustc_data_structures::captures::Captures;
27 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
28 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
30 use rustc_hir::def::{CtorKind, DefKind};
31 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
32 use rustc_hir::intravisit::{self, Visitor};
33 use rustc_hir::weak_lang_items;
34 use rustc_hir::{GenericParamKind, HirId, Node};
35 use rustc_middle::hir::nested_filter;
36 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
37 use rustc_middle::mir::mono::Linkage;
38 use rustc_middle::ty::query::Providers;
39 use rustc_middle::ty::subst::InternalSubsts;
40 use rustc_middle::ty::util::Discr;
41 use rustc_middle::ty::util::IntTypeExt;
42 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, IsSuggestable, Ty, TyCtxt};
43 use rustc_middle::ty::{ReprOptions, ToPredicate};
44 use rustc_session::lint;
45 use rustc_session::parse::feature_err;
46 use rustc_span::symbol::{kw, sym, Ident, Symbol};
47 use rustc_span::{Span, DUMMY_SP};
48 use rustc_target::spec::{abi, SanitizerSet};
49 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
56 struct OnlySelfBounds(bool);
58 ///////////////////////////////////////////////////////////////////////////
61 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
62 tcx.hir().deep_visit_item_likes_in_module(module_def_id, &mut CollectItemTypesVisitor { tcx });
65 pub fn provide(providers: &mut Providers) {
66 *providers = Providers {
67 opt_const_param_of: type_of::opt_const_param_of,
68 type_of: type_of::type_of,
69 item_bounds: item_bounds::item_bounds,
70 explicit_item_bounds: item_bounds::explicit_item_bounds,
73 predicates_defined_on,
74 explicit_predicates_of,
76 super_predicates_that_define_assoc_type,
77 trait_explicit_predicates_and_bounds,
78 type_param_predicates,
88 collect_mod_item_types,
89 should_inherit_track_caller,
94 ///////////////////////////////////////////////////////////////////////////
96 /// Context specific to some particular item. This is what implements
97 /// `AstConv`. It has information about the predicates that are defined
98 /// on the trait. Unfortunately, this predicate information is
99 /// available in various different forms at various points in the
100 /// process. So we can't just store a pointer to e.g., the AST or the
101 /// parsed ty form, we have to be more flexible. To this end, the
102 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
103 /// `get_type_parameter_bounds` requests, drawing the information from
104 /// the AST (`hir::Generics`), recursively.
105 pub struct ItemCtxt<'tcx> {
110 ///////////////////////////////////////////////////////////////////////////
113 pub(crate) struct HirPlaceholderCollector(pub(crate) Vec<Span>);
115 impl<'v> Visitor<'v> for HirPlaceholderCollector {
116 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
117 if let hir::TyKind::Infer = t.kind {
120 intravisit::walk_ty(self, t)
122 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
124 hir::GenericArg::Infer(inf) => {
125 self.0.push(inf.span);
126 intravisit::walk_inf(self, inf);
128 hir::GenericArg::Type(t) => self.visit_ty(t),
132 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
133 if let &hir::ArrayLen::Infer(_, span) = length {
136 intravisit::walk_array_len(self, length)
140 struct CollectItemTypesVisitor<'tcx> {
144 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
145 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
146 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
147 pub(crate) fn placeholder_type_error<'tcx>(
149 generics: Option<&hir::Generics<'_>>,
150 placeholder_types: Vec<Span>,
152 hir_ty: Option<&hir::Ty<'_>>,
155 if placeholder_types.is_empty() {
159 placeholder_type_error_diag(tcx, generics, placeholder_types, vec![], suggest, hir_ty, kind)
163 pub(crate) fn placeholder_type_error_diag<'tcx>(
165 generics: Option<&hir::Generics<'_>>,
166 placeholder_types: Vec<Span>,
167 additional_spans: Vec<Span>,
169 hir_ty: Option<&hir::Ty<'_>>,
171 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
172 if placeholder_types.is_empty() {
173 return bad_placeholder(tcx, additional_spans, kind);
176 let params = generics.map(|g| g.params).unwrap_or_default();
177 let type_name = params.next_type_param_name(None);
178 let mut sugg: Vec<_> =
179 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
181 if let Some(generics) = generics {
182 if let Some(arg) = params.iter().find(|arg| {
183 matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. }))
185 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
186 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
187 sugg.push((arg.span, (*type_name).to_string()));
188 } else if let Some(span) = generics.span_for_param_suggestion() {
189 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
190 sugg.push((span, format!(", {}", type_name)));
192 sugg.push((generics.span, format!("<{}>", type_name)));
197 bad_placeholder(tcx, placeholder_types.into_iter().chain(additional_spans).collect(), kind);
199 // Suggest, but only if it is not a function in const or static
201 let mut is_fn = false;
202 let mut is_const_or_static = false;
204 if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind {
207 // Check if parent is const or static
208 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
209 let parent_node = tcx.hir().get(parent_id);
211 is_const_or_static = matches!(
213 Node::Item(&hir::Item {
214 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
216 }) | Node::TraitItem(&hir::TraitItem {
217 kind: hir::TraitItemKind::Const(..),
219 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
223 // if function is wrapped around a const or static,
224 // then don't show the suggestion
225 if !(is_fn && is_const_or_static) {
226 err.multipart_suggestion(
227 "use type parameters instead",
229 Applicability::HasPlaceholders,
237 fn reject_placeholder_type_signatures_in_item<'tcx>(
239 item: &'tcx hir::Item<'tcx>,
241 let (generics, suggest) = match &item.kind {
242 hir::ItemKind::Union(_, generics)
243 | hir::ItemKind::Enum(_, generics)
244 | hir::ItemKind::TraitAlias(generics, _)
245 | hir::ItemKind::Trait(_, _, generics, ..)
246 | hir::ItemKind::Impl(hir::Impl { generics, .. })
247 | hir::ItemKind::Struct(_, generics) => (generics, true),
248 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
249 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
250 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
254 let mut visitor = HirPlaceholderCollector::default();
255 visitor.visit_item(item);
257 placeholder_type_error(tcx, Some(generics), visitor.0, suggest, None, item.kind.descr());
260 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
261 type NestedFilter = nested_filter::OnlyBodies;
263 fn nested_visit_map(&mut self) -> Self::Map {
267 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
268 convert_item(self.tcx, item.item_id());
269 reject_placeholder_type_signatures_in_item(self.tcx, item);
270 intravisit::walk_item(self, item);
273 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
274 for param in generics.params {
276 hir::GenericParamKind::Lifetime { .. } => {}
277 hir::GenericParamKind::Type { default: Some(_), .. } => {
278 let def_id = self.tcx.hir().local_def_id(param.hir_id);
279 self.tcx.ensure().type_of(def_id);
281 hir::GenericParamKind::Type { .. } => {}
282 hir::GenericParamKind::Const { default, .. } => {
283 let def_id = self.tcx.hir().local_def_id(param.hir_id);
284 self.tcx.ensure().type_of(def_id);
285 if let Some(default) = default {
286 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
287 // need to store default and type of default
288 self.tcx.ensure().type_of(default_def_id);
289 self.tcx.ensure().const_param_default(def_id);
294 intravisit::walk_generics(self, generics);
297 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
298 if let hir::ExprKind::Closure { .. } = expr.kind {
299 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
300 self.tcx.ensure().generics_of(def_id);
301 // We do not call `type_of` for closures here as that
302 // depends on typecheck and would therefore hide
303 // any further errors in case one typeck fails.
305 intravisit::walk_expr(self, expr);
308 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
309 convert_trait_item(self.tcx, trait_item.trait_item_id());
310 intravisit::walk_trait_item(self, trait_item);
313 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
314 convert_impl_item(self.tcx, impl_item.impl_item_id());
315 intravisit::walk_impl_item(self, impl_item);
319 ///////////////////////////////////////////////////////////////////////////
320 // Utility types and common code for the above passes.
322 fn bad_placeholder<'tcx>(
324 mut spans: Vec<Span>,
326 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
327 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
330 let mut err = struct_span_err!(
334 "the placeholder `_` is not allowed within types on item signatures for {}",
338 err.span_label(span, "not allowed in type signatures");
343 impl<'tcx> ItemCtxt<'tcx> {
344 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
345 ItemCtxt { tcx, item_def_id }
348 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
349 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
352 pub fn hir_id(&self) -> hir::HirId {
353 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
356 pub fn node(&self) -> hir::Node<'tcx> {
357 self.tcx.hir().get(self.hir_id())
361 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
362 fn tcx(&self) -> TyCtxt<'tcx> {
366 fn item_def_id(&self) -> Option<DefId> {
367 Some(self.item_def_id)
370 fn get_type_parameter_bounds(
375 ) -> ty::GenericPredicates<'tcx> {
376 self.tcx.at(span).type_param_predicates((
378 def_id.expect_local(),
383 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
387 fn allow_ty_infer(&self) -> bool {
391 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
392 self.tcx().ty_error_with_message(span, "bad placeholder type")
395 fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
396 let ty = self.tcx.fold_regions(ty, |r, _| match *r {
397 ty::ReErased => self.tcx.lifetimes.re_static,
400 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
403 fn projected_ty_from_poly_trait_ref(
407 item_segment: &hir::PathSegment<'_>,
408 poly_trait_ref: ty::PolyTraitRef<'tcx>,
410 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
411 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
419 self.tcx().mk_projection(item_def_id, item_substs)
421 // There are no late-bound regions; we can just ignore the binder.
422 let mut err = struct_span_err!(
426 "cannot use the associated type of a trait \
427 with uninferred generic parameters"
431 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
433 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
435 hir::ItemKind::Enum(_, generics)
436 | hir::ItemKind::Struct(_, generics)
437 | hir::ItemKind::Union(_, generics) => {
438 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
439 let (lt_sp, sugg) = match generics.params {
440 [] => (generics.span, format!("<{}>", lt_name)),
442 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
445 let suggestions = vec![
448 span.with_hi(item_segment.ident.span.lo()),
451 // Replace the existing lifetimes with a new named lifetime.
452 self.tcx.replace_late_bound_regions_uncached(
455 self.tcx.mk_region(ty::ReEarlyBound(
456 ty::EarlyBoundRegion {
459 name: Symbol::intern(<_name),
467 err.multipart_suggestion(
468 "use a fully qualified path with explicit lifetimes",
470 Applicability::MaybeIncorrect,
476 hir::Node::Item(hir::Item {
478 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
482 | hir::Node::ForeignItem(_)
483 | hir::Node::TraitItem(_)
484 | hir::Node::ImplItem(_) => {
485 err.span_suggestion_verbose(
486 span.with_hi(item_segment.ident.span.lo()),
487 "use a fully qualified path with inferred lifetimes",
490 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
491 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
493 Applicability::MaybeIncorrect,
499 self.tcx().ty_error()
503 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
504 // Types in item signatures are not normalized to avoid undue dependencies.
508 fn set_tainted_by_errors(&self) {
509 // There's no obvious place to track this, so just let it go.
512 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
513 // There's no place to record types from signatures?
517 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
518 fn get_new_lifetime_name<'tcx>(
520 poly_trait_ref: ty::PolyTraitRef<'tcx>,
521 generics: &hir::Generics<'tcx>,
523 let existing_lifetimes = tcx
524 .collect_referenced_late_bound_regions(&poly_trait_ref)
527 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
528 Some(name.as_str().to_string())
533 .chain(generics.params.iter().filter_map(|param| {
534 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
535 Some(param.name.ident().as_str().to_string())
540 .collect::<FxHashSet<String>>();
542 let a_to_z_repeat_n = |n| {
543 (b'a'..=b'z').map(move |c| {
544 let mut s = '\''.to_string();
545 s.extend(std::iter::repeat(char::from(c)).take(n));
550 // If all single char lifetime names are present, we wrap around and double the chars.
551 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
554 /// Returns the predicates defined on `item_def_id` of the form
555 /// `X: Foo` where `X` is the type parameter `def_id`.
556 fn type_param_predicates(
558 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
559 ) -> ty::GenericPredicates<'_> {
562 // In the AST, bounds can derive from two places. Either
563 // written inline like `<T: Foo>` or in a where-clause like
566 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
567 let param_owner = tcx.hir().ty_param_owner(def_id);
568 let generics = tcx.generics_of(param_owner);
569 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
570 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
572 // Don't look for bounds where the type parameter isn't in scope.
573 let parent = if item_def_id == param_owner.to_def_id() {
576 tcx.generics_of(item_def_id).parent
579 let mut result = parent
581 let icx = ItemCtxt::new(tcx, parent);
582 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
584 .unwrap_or_default();
585 let mut extend = None;
587 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
588 let ast_generics = match tcx.hir().get(item_hir_id) {
589 Node::TraitItem(item) => &item.generics,
591 Node::ImplItem(item) => &item.generics,
593 Node::Item(item) => {
595 ItemKind::Fn(.., ref generics, _)
596 | ItemKind::Impl(hir::Impl { ref generics, .. })
597 | ItemKind::TyAlias(_, ref generics)
598 | ItemKind::OpaqueTy(OpaqueTy {
600 origin: hir::OpaqueTyOrigin::TyAlias,
603 | ItemKind::Enum(_, ref generics)
604 | ItemKind::Struct(_, ref generics)
605 | ItemKind::Union(_, ref generics) => generics,
606 ItemKind::Trait(_, _, ref generics, ..) => {
607 // Implied `Self: Trait` and supertrait bounds.
608 if param_id == item_hir_id {
609 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
611 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
619 Node::ForeignItem(item) => match item.kind {
620 ForeignItemKind::Fn(_, _, ref generics) => generics,
627 let icx = ItemCtxt::new(tcx, item_def_id);
628 let extra_predicates = extend.into_iter().chain(
629 icx.type_parameter_bounds_in_generics(
633 OnlySelfBounds(true),
637 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
638 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
643 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
647 impl<'tcx> ItemCtxt<'tcx> {
648 /// Finds bounds from `hir::Generics`. This requires scanning through the
649 /// AST. We do this to avoid having to convert *all* the bounds, which
650 /// would create artificial cycles. Instead, we can only convert the
651 /// bounds for a type parameter `X` if `X::Foo` is used.
652 #[instrument(level = "trace", skip(self, ast_generics))]
653 fn type_parameter_bounds_in_generics(
655 ast_generics: &'tcx hir::Generics<'tcx>,
656 param_id: hir::HirId,
658 only_self_bounds: OnlySelfBounds,
659 assoc_name: Option<Ident>,
660 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
661 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
662 debug!(?param_def_id);
666 .filter_map(|wp| match *wp {
667 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
671 let bt = if bp.is_param_bound(param_def_id) {
673 } else if !only_self_bounds.0 {
674 Some(self.to_ty(bp.bounded_ty))
678 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
680 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b, bvars))).filter(
681 |(_, b, _)| match assoc_name {
682 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
687 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars))
691 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
692 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
695 hir::GenericBound::Trait(poly_trait_ref, _) => {
696 let trait_ref = &poly_trait_ref.trait_ref;
697 if let Some(trait_did) = trait_ref.trait_def_id() {
698 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
708 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
709 let it = tcx.hir().item(item_id);
710 debug!("convert: item {} with id {}", it.ident, it.hir_id());
711 let def_id = item_id.def_id;
714 // These don't define types.
715 hir::ItemKind::ExternCrate(_)
716 | hir::ItemKind::Use(..)
717 | hir::ItemKind::Macro(..)
718 | hir::ItemKind::Mod(_)
719 | hir::ItemKind::GlobalAsm(_) => {}
720 hir::ItemKind::ForeignMod { items, .. } => {
722 let item = tcx.hir().foreign_item(item.id);
723 tcx.ensure().generics_of(item.def_id);
724 tcx.ensure().type_of(item.def_id);
725 tcx.ensure().predicates_of(item.def_id);
727 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
728 hir::ForeignItemKind::Static(..) => {
729 let mut visitor = HirPlaceholderCollector::default();
730 visitor.visit_foreign_item(item);
731 placeholder_type_error(
744 hir::ItemKind::Enum(ref enum_definition, _) => {
745 tcx.ensure().generics_of(def_id);
746 tcx.ensure().type_of(def_id);
747 tcx.ensure().predicates_of(def_id);
748 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
750 hir::ItemKind::Impl { .. } => {
751 tcx.ensure().generics_of(def_id);
752 tcx.ensure().type_of(def_id);
753 tcx.ensure().impl_trait_ref(def_id);
754 tcx.ensure().predicates_of(def_id);
756 hir::ItemKind::Trait(..) => {
757 tcx.ensure().generics_of(def_id);
758 tcx.ensure().trait_def(def_id);
759 tcx.at(it.span).super_predicates_of(def_id);
760 tcx.ensure().predicates_of(def_id);
762 hir::ItemKind::TraitAlias(..) => {
763 tcx.ensure().generics_of(def_id);
764 tcx.at(it.span).super_predicates_of(def_id);
765 tcx.ensure().predicates_of(def_id);
767 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
768 tcx.ensure().generics_of(def_id);
769 tcx.ensure().type_of(def_id);
770 tcx.ensure().predicates_of(def_id);
772 for f in struct_def.fields() {
773 let def_id = tcx.hir().local_def_id(f.hir_id);
774 tcx.ensure().generics_of(def_id);
775 tcx.ensure().type_of(def_id);
776 tcx.ensure().predicates_of(def_id);
779 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
780 convert_variant_ctor(tcx, ctor_hir_id);
784 // Desugared from `impl Trait`, so visited by the function's return type.
785 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
786 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
790 // Don't call `type_of` on opaque types, since that depends on type
791 // checking function bodies. `check_item_type` ensures that it's called
793 hir::ItemKind::OpaqueTy(..) => {
794 tcx.ensure().generics_of(def_id);
795 tcx.ensure().predicates_of(def_id);
796 tcx.ensure().explicit_item_bounds(def_id);
798 hir::ItemKind::TyAlias(..)
799 | hir::ItemKind::Static(..)
800 | hir::ItemKind::Const(..)
801 | hir::ItemKind::Fn(..) => {
802 tcx.ensure().generics_of(def_id);
803 tcx.ensure().type_of(def_id);
804 tcx.ensure().predicates_of(def_id);
806 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
807 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
808 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
809 if !is_suggestable_infer_ty(ty) {
810 let mut visitor = HirPlaceholderCollector::default();
811 visitor.visit_item(it);
812 placeholder_type_error(tcx, None, visitor.0, false, None, it.kind.descr());
821 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
822 let trait_item = tcx.hir().trait_item(trait_item_id);
823 tcx.ensure().generics_of(trait_item_id.def_id);
825 match trait_item.kind {
826 hir::TraitItemKind::Fn(..) => {
827 tcx.ensure().type_of(trait_item_id.def_id);
828 tcx.ensure().fn_sig(trait_item_id.def_id);
831 hir::TraitItemKind::Const(.., Some(_)) => {
832 tcx.ensure().type_of(trait_item_id.def_id);
835 hir::TraitItemKind::Const(..) => {
836 tcx.ensure().type_of(trait_item_id.def_id);
837 // Account for `const C: _;`.
838 let mut visitor = HirPlaceholderCollector::default();
839 visitor.visit_trait_item(trait_item);
840 placeholder_type_error(tcx, None, visitor.0, false, None, "constant");
843 hir::TraitItemKind::Type(_, Some(_)) => {
844 tcx.ensure().item_bounds(trait_item_id.def_id);
845 tcx.ensure().type_of(trait_item_id.def_id);
846 // Account for `type T = _;`.
847 let mut visitor = HirPlaceholderCollector::default();
848 visitor.visit_trait_item(trait_item);
849 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
852 hir::TraitItemKind::Type(_, None) => {
853 tcx.ensure().item_bounds(trait_item_id.def_id);
854 // #74612: Visit and try to find bad placeholders
855 // even if there is no concrete type.
856 let mut visitor = HirPlaceholderCollector::default();
857 visitor.visit_trait_item(trait_item);
859 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
863 tcx.ensure().predicates_of(trait_item_id.def_id);
866 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
867 let def_id = impl_item_id.def_id;
868 tcx.ensure().generics_of(def_id);
869 tcx.ensure().type_of(def_id);
870 tcx.ensure().predicates_of(def_id);
871 let impl_item = tcx.hir().impl_item(impl_item_id);
872 match impl_item.kind {
873 hir::ImplItemKind::Fn(..) => {
874 tcx.ensure().fn_sig(def_id);
876 hir::ImplItemKind::TyAlias(_) => {
877 // Account for `type T = _;`
878 let mut visitor = HirPlaceholderCollector::default();
879 visitor.visit_impl_item(impl_item);
881 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
883 hir::ImplItemKind::Const(..) => {}
887 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
888 let def_id = tcx.hir().local_def_id(ctor_id);
889 tcx.ensure().generics_of(def_id);
890 tcx.ensure().type_of(def_id);
891 tcx.ensure().predicates_of(def_id);
894 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
895 let def = tcx.adt_def(def_id);
896 let repr_type = def.repr().discr_type();
897 let initial = repr_type.initial_discriminant(tcx);
898 let mut prev_discr = None::<Discr<'_>>;
900 // fill the discriminant values and field types
901 for variant in variants {
902 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
904 if let Some(ref e) = variant.disr_expr {
905 let expr_did = tcx.hir().local_def_id(e.hir_id);
906 def.eval_explicit_discr(tcx, expr_did.to_def_id())
907 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
910 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
913 format!("overflowed on value after {}", prev_discr.unwrap()),
916 "explicitly set `{} = {}` if that is desired outcome",
917 variant.ident, wrapped_discr
922 .unwrap_or(wrapped_discr),
925 for f in variant.data.fields() {
926 let def_id = tcx.hir().local_def_id(f.hir_id);
927 tcx.ensure().generics_of(def_id);
928 tcx.ensure().type_of(def_id);
929 tcx.ensure().predicates_of(def_id);
932 // Convert the ctor, if any. This also registers the variant as
934 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
935 convert_variant_ctor(tcx, ctor_hir_id);
942 variant_did: Option<LocalDefId>,
943 ctor_did: Option<LocalDefId>,
945 discr: ty::VariantDiscr,
946 def: &hir::VariantData<'_>,
947 adt_kind: ty::AdtKind,
948 parent_did: LocalDefId,
949 ) -> ty::VariantDef {
950 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
955 let fid = tcx.hir().local_def_id(f.hir_id);
956 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
957 if let Some(prev_span) = dup_span {
958 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
964 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
967 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
970 let recovered = match def {
971 hir::VariantData::Struct(_, r) => *r,
976 variant_did.map(LocalDefId::to_def_id),
977 ctor_did.map(LocalDefId::to_def_id),
980 CtorKind::from_hir(def),
982 parent_did.to_def_id(),
984 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
985 || variant_did.map_or(false, |variant_did| {
986 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
991 fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
994 let def_id = def_id.expect_local();
995 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
996 let Node::Item(item) = tcx.hir().get(hir_id) else {
1000 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1001 let (kind, variants) = match item.kind {
1002 ItemKind::Enum(ref def, _) => {
1003 let mut distance_from_explicit = 0;
1008 let variant_did = Some(tcx.hir().local_def_id(v.id));
1010 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1012 let discr = if let Some(ref e) = v.disr_expr {
1013 distance_from_explicit = 0;
1014 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1016 ty::VariantDiscr::Relative(distance_from_explicit)
1018 distance_from_explicit += 1;
1033 (AdtKind::Enum, variants)
1035 ItemKind::Struct(ref def, _) => {
1036 let variant_did = None::<LocalDefId>;
1037 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1039 let variants = std::iter::once(convert_variant(
1044 ty::VariantDiscr::Relative(0),
1051 (AdtKind::Struct, variants)
1053 ItemKind::Union(ref def, _) => {
1054 let variant_did = None;
1055 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1057 let variants = std::iter::once(convert_variant(
1062 ty::VariantDiscr::Relative(0),
1069 (AdtKind::Union, variants)
1073 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1076 /// Ensures that the super-predicates of the trait with a `DefId`
1077 /// of `trait_def_id` are converted and stored. This also ensures that
1078 /// the transitive super-predicates are converted.
1079 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1080 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1081 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1084 /// Ensures that the super-predicates of the trait with a `DefId`
1085 /// of `trait_def_id` are converted and stored. This also ensures that
1086 /// the transitive super-predicates are converted.
1087 fn super_predicates_that_define_assoc_type(
1089 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1090 ) -> ty::GenericPredicates<'_> {
1092 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1093 trait_def_id, assoc_name
1095 if trait_def_id.is_local() {
1096 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1097 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1099 let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
1100 bug!("trait_node_id {} is not an item", trait_hir_id);
1103 let (generics, bounds) = match item.kind {
1104 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1105 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1106 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1109 let icx = ItemCtxt::new(tcx, trait_def_id);
1111 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1112 let self_param_ty = tcx.types.self_param;
1113 let superbounds1 = if let Some(assoc_name) = assoc_name {
1114 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1121 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1124 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1126 // Convert any explicit superbounds in the where-clause,
1127 // e.g., `trait Foo where Self: Bar`.
1128 // In the case of trait aliases, however, we include all bounds in the where-clause,
1129 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1130 // as one of its "superpredicates".
1131 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1132 let superbounds2 = icx.type_parameter_bounds_in_generics(
1136 OnlySelfBounds(!is_trait_alias),
1140 // Combine the two lists to form the complete set of superbounds:
1141 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1142 debug!(?superbounds);
1144 // Now require that immediate supertraits are converted,
1145 // which will, in turn, reach indirect supertraits.
1146 if assoc_name.is_none() {
1147 // Now require that immediate supertraits are converted,
1148 // which will, in turn, reach indirect supertraits.
1149 for &(pred, span) in superbounds {
1150 debug!("superbound: {:?}", pred);
1151 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1152 tcx.at(span).super_predicates_of(bound.def_id());
1157 ty::GenericPredicates { parent: None, predicates: superbounds }
1159 // if `assoc_name` is None, then the query should've been redirected to an
1160 // external provider
1161 assert!(assoc_name.is_some());
1162 tcx.super_predicates_of(trait_def_id)
1166 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1167 let item = tcx.hir().expect_item(def_id.expect_local());
1169 let (is_auto, unsafety, items) = match item.kind {
1170 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1171 (is_auto == hir::IsAuto::Yes, unsafety, items)
1173 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1174 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1177 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1178 if paren_sugar && !tcx.features().unboxed_closures {
1182 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1183 which traits can use parenthetical notation",
1185 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1189 let is_marker = tcx.has_attr(def_id, sym::marker);
1190 let skip_array_during_method_dispatch =
1191 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1192 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1193 ty::trait_def::TraitSpecializationKind::Marker
1194 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1195 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1197 ty::trait_def::TraitSpecializationKind::None
1199 let must_implement_one_of = tcx
1200 .get_attr(def_id, sym::rustc_must_implement_one_of)
1201 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1202 // and that they are all identifiers
1203 .and_then(|attr| match attr.meta_item_list() {
1204 Some(items) if items.len() < 2 => {
1208 "the `#[rustc_must_implement_one_of]` attribute must be \
1209 used with at least 2 args",
1215 Some(items) => items
1217 .map(|item| item.ident().ok_or(item.span()))
1218 .collect::<Result<Box<[_]>, _>>()
1221 .struct_span_err(span, "must be a name of an associated function")
1225 .zip(Some(attr.span)),
1226 // Error is reported by `rustc_attr!`
1229 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1230 // functions in the trait with default implementations
1231 .and_then(|(list, attr_span)| {
1232 let errors = list.iter().filter_map(|ident| {
1233 let item = items.iter().find(|item| item.ident == *ident);
1236 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1237 if !item.defaultness.has_value() {
1241 "This function doesn't have a default implementation",
1243 .span_note(attr_span, "required by this annotation")
1253 .struct_span_err(item.span, "Not a function")
1254 .span_note(attr_span, "required by this annotation")
1256 "All `#[rustc_must_implement_one_of]` arguments \
1257 must be associated function names",
1263 .struct_span_err(ident.span, "Function not found in this trait")
1271 (errors.count() == 0).then_some(list)
1273 // Check for duplicates
1275 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1276 let mut no_dups = true;
1278 for ident in &*list {
1279 if let Some(dup) = set.insert(ident.name, ident.span) {
1281 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1283 "All `#[rustc_must_implement_one_of]` arguments \
1292 no_dups.then_some(list)
1301 skip_array_during_method_dispatch,
1303 must_implement_one_of,
1307 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1308 struct LateBoundRegionsDetector<'tcx> {
1310 outer_index: ty::DebruijnIndex,
1311 has_late_bound_regions: Option<Span>,
1314 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1315 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1316 if self.has_late_bound_regions.is_some() {
1320 hir::TyKind::BareFn(..) => {
1321 self.outer_index.shift_in(1);
1322 intravisit::walk_ty(self, ty);
1323 self.outer_index.shift_out(1);
1325 _ => intravisit::walk_ty(self, ty),
1329 fn visit_poly_trait_ref(
1331 tr: &'tcx hir::PolyTraitRef<'tcx>,
1332 m: hir::TraitBoundModifier,
1334 if self.has_late_bound_regions.is_some() {
1337 self.outer_index.shift_in(1);
1338 intravisit::walk_poly_trait_ref(self, tr, m);
1339 self.outer_index.shift_out(1);
1342 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1343 if self.has_late_bound_regions.is_some() {
1347 match self.tcx.named_region(lt.hir_id) {
1348 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1350 rl::Region::LateBound(debruijn, _, _)
1351 | rl::Region::LateBoundAnon(debruijn, _, _),
1352 ) if debruijn < self.outer_index => {}
1354 rl::Region::LateBound(..)
1355 | rl::Region::LateBoundAnon(..)
1356 | rl::Region::Free(..),
1359 self.has_late_bound_regions = Some(lt.span);
1365 fn has_late_bound_regions<'tcx>(
1367 generics: &'tcx hir::Generics<'tcx>,
1368 decl: &'tcx hir::FnDecl<'tcx>,
1370 let mut visitor = LateBoundRegionsDetector {
1372 outer_index: ty::INNERMOST,
1373 has_late_bound_regions: None,
1375 for param in generics.params {
1376 if let GenericParamKind::Lifetime { .. } = param.kind {
1377 if tcx.is_late_bound(param.hir_id) {
1378 return Some(param.span);
1382 visitor.visit_fn_decl(decl);
1383 visitor.has_late_bound_regions
1387 Node::TraitItem(item) => match item.kind {
1388 hir::TraitItemKind::Fn(ref sig, _) => {
1389 has_late_bound_regions(tcx, &item.generics, sig.decl)
1393 Node::ImplItem(item) => match item.kind {
1394 hir::ImplItemKind::Fn(ref sig, _) => {
1395 has_late_bound_regions(tcx, &item.generics, sig.decl)
1399 Node::ForeignItem(item) => match item.kind {
1400 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1401 has_late_bound_regions(tcx, generics, fn_decl)
1405 Node::Item(item) => match item.kind {
1406 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1407 has_late_bound_regions(tcx, generics, sig.decl)
1415 struct AnonConstInParamTyDetector {
1417 found_anon_const_in_param_ty: bool,
1421 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1422 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1423 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1424 let prev = self.in_param_ty;
1425 self.in_param_ty = true;
1427 self.in_param_ty = prev;
1431 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1432 if self.in_param_ty && self.ct == c.hir_id {
1433 self.found_anon_const_in_param_ty = true;
1435 intravisit::walk_anon_const(self, c)
1440 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1443 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1445 let node = tcx.hir().get(hir_id);
1446 let parent_def_id = match node {
1448 | Node::TraitItem(_)
1451 | Node::Field(_) => {
1452 let parent_id = tcx.hir().get_parent_item(hir_id);
1453 Some(parent_id.to_def_id())
1455 // FIXME(#43408) always enable this once `lazy_normalization` is
1456 // stable enough and does not need a feature gate anymore.
1457 Node::AnonConst(_) => {
1458 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1460 let mut in_param_ty = false;
1461 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1462 if let Some(generics) = node.generics() {
1463 let mut visitor = AnonConstInParamTyDetector {
1465 found_anon_const_in_param_ty: false,
1469 visitor.visit_generics(generics);
1470 in_param_ty = visitor.found_anon_const_in_param_ty;
1476 // We do not allow generic parameters in anon consts if we are inside
1477 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1479 } else if tcx.lazy_normalization() {
1480 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1481 // If the def_id we are calling generics_of on is an anon ct default i.e:
1483 // struct Foo<const N: usize = { .. }>;
1484 // ^^^ ^ ^^^^^^ def id of this anon const
1488 // then we only want to return generics for params to the left of `N`. If we don't do that we
1489 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1491 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1492 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1493 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1495 // We fix this by having this function return the parent's generics ourselves and truncating the
1496 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1498 // For the above code example that means we want `substs: []`
1499 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1500 // the def id of the `{ N + 1 }` anon const
1501 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1503 // This has some implications for how we get the predicates available to the anon const
1504 // see `explicit_predicates_of` for more information on this
1505 let generics = tcx.generics_of(parent_def_id.to_def_id());
1506 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1507 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1508 // In the above example this would be .params[..N#0]
1509 let params = generics.params[..param_def_idx as usize].to_owned();
1510 let param_def_id_to_index =
1511 params.iter().map(|param| (param.def_id, param.index)).collect();
1513 return ty::Generics {
1514 // we set the parent of these generics to be our parent's parent so that we
1515 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1516 // struct Foo<const N: usize, const M: usize = { ... }>;
1517 parent: generics.parent,
1518 parent_count: generics.parent_count,
1520 param_def_id_to_index,
1521 has_self: generics.has_self,
1522 has_late_bound_regions: generics.has_late_bound_regions,
1526 // HACK(eddyb) this provides the correct generics when
1527 // `feature(generic_const_expressions)` is enabled, so that const expressions
1528 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1530 // Note that we do not supply the parent generics when using
1531 // `min_const_generics`.
1532 Some(parent_def_id.to_def_id())
1534 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1536 // HACK(eddyb) this provides the correct generics for repeat
1537 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1538 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1539 // as they shouldn't be able to cause query cycle errors.
1540 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1541 if constant.hir_id() == hir_id =>
1543 Some(parent_def_id.to_def_id())
1545 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1546 if constant.hir_id == hir_id =>
1548 Some(parent_def_id.to_def_id())
1550 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1551 Some(tcx.typeck_root_def_id(def_id))
1553 // Exclude `GlobalAsm` here which cannot have generics.
1554 Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
1555 if asm.operands.iter().any(|(op, _op_sp)| match op {
1556 hir::InlineAsmOperand::Const { anon_const }
1557 | hir::InlineAsmOperand::SymFn { anon_const } => {
1558 anon_const.hir_id == hir_id
1563 Some(parent_def_id.to_def_id())
1569 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
1570 Some(tcx.typeck_root_def_id(def_id))
1572 Node::Item(item) => match item.kind {
1573 ItemKind::OpaqueTy(hir::OpaqueTy {
1575 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1577 }) => Some(fn_def_id.to_def_id()),
1578 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1579 let parent_id = tcx.hir().get_parent_item(hir_id);
1580 assert_ne!(parent_id, CRATE_DEF_ID);
1581 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1582 // Opaque types are always nested within another item, and
1583 // inherit the generics of the item.
1584 Some(parent_id.to_def_id())
1591 let no_generics = hir::Generics::empty();
1592 let ast_generics = node.generics().unwrap_or(&no_generics);
1593 let (opt_self, allow_defaults) = match node {
1594 Node::Item(item) => {
1596 ItemKind::Trait(..) | ItemKind::TraitAlias(..) => {
1597 // Add in the self type parameter.
1599 // Something of a hack: use the node id for the trait, also as
1600 // the node id for the Self type parameter.
1601 let opt_self = Some(ty::GenericParamDef {
1603 name: kw::SelfUpper,
1605 pure_wrt_drop: false,
1606 kind: ty::GenericParamDefKind::Type {
1608 object_lifetime_default: rl::Set1::Empty,
1615 ItemKind::TyAlias(..)
1616 | ItemKind::Enum(..)
1617 | ItemKind::Struct(..)
1618 | ItemKind::OpaqueTy(..)
1619 | ItemKind::Union(..) => (None, true),
1626 let has_self = opt_self.is_some();
1627 let mut parent_has_self = false;
1628 let mut own_start = has_self as u32;
1629 let parent_count = parent_def_id.map_or(0, |def_id| {
1630 let generics = tcx.generics_of(def_id);
1632 parent_has_self = generics.has_self;
1633 own_start = generics.count() as u32;
1634 generics.parent_count + generics.params.len()
1637 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1639 if let Some(opt_self) = opt_self {
1640 params.push(opt_self);
1643 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1644 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1645 name: param.name.ident().name,
1646 index: own_start + i as u32,
1647 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1648 pure_wrt_drop: param.pure_wrt_drop,
1649 kind: ty::GenericParamDefKind::Lifetime,
1652 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id.owner);
1654 // Now create the real type and const parameters.
1655 let type_start = own_start - has_self as u32 + params.len() as u32;
1658 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1659 GenericParamKind::Lifetime { .. } => None,
1660 GenericParamKind::Type { ref default, synthetic, .. } => {
1661 if !allow_defaults && default.is_some() {
1662 if !tcx.features().default_type_parameter_fallback {
1663 tcx.struct_span_lint_hir(
1664 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1669 "defaults for type parameters are only allowed in \
1670 `struct`, `enum`, `type`, or `trait` definitions",
1678 let kind = ty::GenericParamDefKind::Type {
1679 has_default: default.is_some(),
1680 object_lifetime_default: object_lifetime_defaults
1682 .map_or(rl::Set1::Empty, |o| o[i]),
1686 let param_def = ty::GenericParamDef {
1687 index: type_start + i as u32,
1688 name: param.name.ident().name,
1689 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1690 pure_wrt_drop: param.pure_wrt_drop,
1696 GenericParamKind::Const { default, .. } => {
1697 if !allow_defaults && default.is_some() {
1700 "defaults for const parameters are only allowed in \
1701 `struct`, `enum`, `type`, or `trait` definitions",
1705 let param_def = ty::GenericParamDef {
1706 index: type_start + i as u32,
1707 name: param.name.ident().name,
1708 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1709 pure_wrt_drop: param.pure_wrt_drop,
1710 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1717 // provide junk type parameter defs - the only place that
1718 // cares about anything but the length is instantiation,
1719 // and we don't do that for closures.
1720 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { movability: gen, .. }, .. }) =
1723 let dummy_args = if gen.is_some() {
1724 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1726 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1729 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1730 index: type_start + i as u32,
1731 name: Symbol::intern(arg),
1733 pure_wrt_drop: false,
1734 kind: ty::GenericParamDefKind::Type {
1736 object_lifetime_default: rl::Set1::Empty,
1742 // provide junk type parameter defs for const blocks.
1743 if let Node::AnonConst(_) = node {
1744 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1745 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1746 params.push(ty::GenericParamDef {
1748 name: Symbol::intern("<const_ty>"),
1750 pure_wrt_drop: false,
1751 kind: ty::GenericParamDefKind::Type {
1753 object_lifetime_default: rl::Set1::Empty,
1760 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1763 parent: parent_def_id,
1766 param_def_id_to_index,
1767 has_self: has_self || parent_has_self,
1768 has_late_bound_regions: has_late_bound_regions(tcx, node),
1772 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1773 generic_args.iter().any(|arg| match arg {
1774 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1775 hir::GenericArg::Infer(_) => true,
1780 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1781 /// use inference to provide suggestions for the appropriate type if possible.
1782 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1787 Slice(ty) => is_suggestable_infer_ty(ty),
1788 Array(ty, length) => {
1789 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1791 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1792 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1793 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1794 Path(hir::QPath::TypeRelative(ty, segment)) => {
1795 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1797 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1798 ty_opt.map_or(false, is_suggestable_infer_ty)
1799 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1805 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1806 if let hir::FnRetTy::Return(ty) = output {
1807 if is_suggestable_infer_ty(ty) {
1814 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1815 use rustc_hir::Node::*;
1818 let def_id = def_id.expect_local();
1819 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1821 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1823 match tcx.hir().get(hir_id) {
1824 TraitItem(hir::TraitItem {
1825 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1829 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => {
1830 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1833 ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => {
1834 // Do not try to inference the return type for a impl method coming from a trait
1835 if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) =
1836 tcx.hir().get(tcx.hir().get_parent_node(hir_id))
1837 && i.of_trait.is_some()
1839 <dyn AstConv<'_>>::ty_of_fn(
1842 sig.header.unsafety,
1849 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1853 TraitItem(hir::TraitItem {
1854 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1857 }) => <dyn AstConv<'_>>::ty_of_fn(
1867 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
1868 let abi = tcx.hir().get_foreign_abi(hir_id);
1869 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi)
1872 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1873 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1875 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1876 ty::Binder::dummy(tcx.mk_fn_sig(
1880 hir::Unsafety::Normal,
1885 Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
1886 // Closure signatures are not like other function
1887 // signatures and cannot be accessed through `fn_sig`. For
1888 // example, a closure signature excludes the `self`
1889 // argument. In any case they are embedded within the
1890 // closure type as part of the `ClosureSubsts`.
1892 // To get the signature of a closure, you should use the
1893 // `sig` method on the `ClosureSubsts`:
1895 // substs.as_closure().sig(def_id, tcx)
1897 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1902 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1907 fn infer_return_ty_for_fn_sig<'tcx>(
1909 sig: &hir::FnSig<'_>,
1910 generics: &hir::Generics<'_>,
1912 icx: &ItemCtxt<'tcx>,
1913 ) -> ty::PolyFnSig<'tcx> {
1914 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1916 match get_infer_ret_ty(&sig.decl.output) {
1918 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1919 // Typeck doesn't expect erased regions to be returned from `type_of`.
1920 let fn_sig = tcx.fold_regions(fn_sig, |r, _| match *r {
1921 ty::ReErased => tcx.lifetimes.re_static,
1924 let fn_sig = ty::Binder::dummy(fn_sig);
1926 let mut visitor = HirPlaceholderCollector::default();
1927 visitor.visit_ty(ty);
1928 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1929 let ret_ty = fn_sig.skip_binder().output();
1930 if ret_ty.is_suggestable(tcx) {
1931 diag.span_suggestion(
1933 "replace with the correct return type",
1935 Applicability::MachineApplicable,
1937 } else if matches!(ret_ty.kind(), ty::FnDef(..)) {
1938 let fn_sig = ret_ty.fn_sig(tcx);
1939 if fn_sig.skip_binder().inputs_and_output.iter().all(|t| t.is_suggestable(tcx)) {
1940 diag.span_suggestion(
1942 "replace with the correct return type",
1944 Applicability::MachineApplicable,
1947 } else if ret_ty.is_closure() {
1948 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1949 // to prevent the user from getting a papercut while trying to use the unique closure
1950 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1951 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1952 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1958 None => <dyn AstConv<'_>>::ty_of_fn(
1961 sig.header.unsafety,
1970 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1971 let icx = ItemCtxt::new(tcx, def_id);
1972 match tcx.hir().expect_item(def_id.expect_local()).kind {
1973 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1974 let selfty = tcx.type_of(def_id);
1975 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1981 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1982 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1983 let item = tcx.hir().expect_item(def_id.expect_local());
1985 hir::ItemKind::Impl(hir::Impl {
1986 polarity: hir::ImplPolarity::Negative(span),
1990 if is_rustc_reservation {
1991 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
1992 tcx.sess.span_err(span, "reservation impls can't be negative");
1994 ty::ImplPolarity::Negative
1996 hir::ItemKind::Impl(hir::Impl {
1997 polarity: hir::ImplPolarity::Positive,
2001 if is_rustc_reservation {
2002 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2004 ty::ImplPolarity::Positive
2006 hir::ItemKind::Impl(hir::Impl {
2007 polarity: hir::ImplPolarity::Positive,
2011 if is_rustc_reservation {
2012 ty::ImplPolarity::Reservation
2014 ty::ImplPolarity::Positive
2017 item => bug!("impl_polarity: {:?} not an impl", item),
2021 /// Returns the early-bound lifetimes declared in this generics
2022 /// listing. For anything other than fns/methods, this is just all
2023 /// the lifetimes that are declared. For fns or methods, we have to
2024 /// screen out those that do not appear in any where-clauses etc using
2025 /// `resolve_lifetime::early_bound_lifetimes`.
2026 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2028 generics: &'a hir::Generics<'a>,
2029 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2030 generics.params.iter().filter(move |param| match param.kind {
2031 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
2036 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2037 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2038 /// inferred constraints concerning which regions outlive other regions.
2039 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2040 debug!("predicates_defined_on({:?})", def_id);
2041 let mut result = tcx.explicit_predicates_of(def_id);
2042 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2043 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2044 if !inferred_outlives.is_empty() {
2046 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2047 def_id, inferred_outlives,
2049 if result.predicates.is_empty() {
2050 result.predicates = inferred_outlives;
2052 result.predicates = tcx
2054 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2058 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2062 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2063 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2064 /// `Self: Trait` predicates for traits.
2065 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2066 let mut result = tcx.predicates_defined_on(def_id);
2068 if tcx.is_trait(def_id) {
2069 // For traits, add `Self: Trait` predicate. This is
2070 // not part of the predicates that a user writes, but it
2071 // is something that one must prove in order to invoke a
2072 // method or project an associated type.
2074 // In the chalk setup, this predicate is not part of the
2075 // "predicates" for a trait item. But it is useful in
2076 // rustc because if you directly (e.g.) invoke a trait
2077 // method like `Trait::method(...)`, you must naturally
2078 // prove that the trait applies to the types that were
2079 // used, and adding the predicate into this list ensures
2080 // that this is done.
2082 // We use a DUMMY_SP here as a way to signal trait bounds that come
2083 // from the trait itself that *shouldn't* be shown as the source of
2084 // an obligation and instead be skipped. Otherwise we'd use
2085 // `tcx.def_span(def_id);`
2086 let span = rustc_span::DUMMY_SP;
2088 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2089 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2093 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2097 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2098 /// N.B., this does not include any implied/inferred constraints.
2099 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2102 debug!("explicit_predicates_of(def_id={:?})", def_id);
2104 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2105 let node = tcx.hir().get(hir_id);
2107 let mut is_trait = None;
2108 let mut is_default_impl_trait = None;
2110 let icx = ItemCtxt::new(tcx, def_id);
2112 const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
2114 // We use an `IndexSet` to preserves order of insertion.
2115 // Preserving the order of insertion is important here so as not to break UI tests.
2116 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2118 let ast_generics = match node {
2119 Node::TraitItem(item) => item.generics,
2121 Node::ImplItem(item) => item.generics,
2123 Node::Item(item) => {
2125 ItemKind::Impl(ref impl_) => {
2126 if impl_.defaultness.is_default() {
2127 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2131 ItemKind::Fn(.., ref generics, _)
2132 | ItemKind::TyAlias(_, ref generics)
2133 | ItemKind::Enum(_, ref generics)
2134 | ItemKind::Struct(_, ref generics)
2135 | ItemKind::Union(_, ref generics) => *generics,
2137 ItemKind::Trait(_, _, ref generics, ..) => {
2138 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2141 ItemKind::TraitAlias(ref generics, _) => {
2142 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2145 ItemKind::OpaqueTy(OpaqueTy {
2146 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2149 // return-position impl trait
2151 // We don't inherit predicates from the parent here:
2152 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2153 // then the return type is `f::<'static, T>::{{opaque}}`.
2155 // If we inherited the predicates of `f` then we would
2156 // require that `T: 'static` to show that the return
2157 // type is well-formed.
2159 // The only way to have something with this opaque type
2160 // is from the return type of the containing function,
2161 // which will ensure that the function's predicates
2163 return ty::GenericPredicates { parent: None, predicates: &[] };
2165 ItemKind::OpaqueTy(OpaqueTy {
2167 origin: hir::OpaqueTyOrigin::TyAlias,
2170 // type-alias impl trait
2178 Node::ForeignItem(item) => match item.kind {
2179 ForeignItemKind::Static(..) => NO_GENERICS,
2180 ForeignItemKind::Fn(_, _, ref generics) => *generics,
2181 ForeignItemKind::Type => NO_GENERICS,
2187 let generics = tcx.generics_of(def_id);
2188 let parent_count = generics.parent_count as u32;
2189 let has_own_self = generics.has_self && parent_count == 0;
2191 // Below we'll consider the bounds on the type parameters (including `Self`)
2192 // and the explicit where-clauses, but to get the full set of predicates
2193 // on a trait we need to add in the supertrait bounds and bounds found on
2194 // associated types.
2195 if let Some(_trait_ref) = is_trait {
2196 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2199 // In default impls, we can assume that the self type implements
2200 // the trait. So in:
2202 // default impl Foo for Bar { .. }
2204 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2205 // (see below). Recall that a default impl is not itself an impl, but rather a
2206 // set of defaults that can be incorporated into another impl.
2207 if let Some(trait_ref) = is_default_impl_trait {
2208 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2211 // Collect the region predicates that were declared inline as
2212 // well. In the case of parameters declared on a fn or method, we
2213 // have to be careful to only iterate over early-bound regions.
2214 let mut index = parent_count
2215 + has_own_self as u32
2216 + early_bound_lifetimes_from_generics(tcx, ast_generics).count() as u32;
2218 // Collect the predicates that were written inline by the user on each
2219 // type parameter (e.g., `<T: Foo>`).
2220 for param in ast_generics.params {
2222 // We already dealt with early bound lifetimes above.
2223 GenericParamKind::Lifetime { .. } => (),
2224 GenericParamKind::Type { .. } => {
2225 let name = param.name.ident().name;
2226 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2229 let mut bounds = Bounds::default();
2230 // Params are implicitly sized unless a `?Sized` bound is found
2231 <dyn AstConv<'_>>::add_implicitly_sized(
2235 Some((param.hir_id, ast_generics.predicates)),
2238 predicates.extend(bounds.predicates(tcx, param_ty));
2240 GenericParamKind::Const { .. } => {
2241 // Bounds on const parameters are currently not possible.
2247 // Add in the bounds that appear in the where-clause.
2248 for predicate in ast_generics.predicates {
2250 hir::WherePredicate::BoundPredicate(bound_pred) => {
2251 let ty = icx.to_ty(bound_pred.bounded_ty);
2252 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2254 // Keep the type around in a dummy predicate, in case of no bounds.
2255 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2256 // is still checked for WF.
2257 if bound_pred.bounds.is_empty() {
2258 if let ty::Param(_) = ty.kind() {
2259 // This is a `where T:`, which can be in the HIR from the
2260 // transformation that moves `?Sized` to `T`'s declaration.
2261 // We can skip the predicate because type parameters are
2262 // trivially WF, but also we *should*, to avoid exposing
2263 // users who never wrote `where Type:,` themselves, to
2264 // compiler/tooling bugs from not handling WF predicates.
2266 let span = bound_pred.bounded_ty.span;
2267 let predicate = ty::Binder::bind_with_vars(
2268 ty::PredicateKind::WellFormed(ty.into()),
2271 predicates.insert((predicate.to_predicate(tcx), span));
2275 let mut bounds = Bounds::default();
2276 <dyn AstConv<'_>>::add_bounds(
2279 bound_pred.bounds.iter(),
2283 predicates.extend(bounds.predicates(tcx, ty));
2286 hir::WherePredicate::RegionPredicate(region_pred) => {
2287 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2288 predicates.extend(region_pred.bounds.iter().map(|bound| {
2289 let (r2, span) = match bound {
2290 hir::GenericBound::Outlives(lt) => {
2291 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2295 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2296 ty::OutlivesPredicate(r1, r2),
2298 .to_predicate(icx.tcx);
2304 hir::WherePredicate::EqPredicate(..) => {
2310 if tcx.features().generic_const_exprs {
2311 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2314 let mut predicates: Vec<_> = predicates.into_iter().collect();
2316 // Subtle: before we store the predicates into the tcx, we
2317 // sort them so that predicates like `T: Foo<Item=U>` come
2318 // before uses of `U`. This avoids false ambiguity errors
2319 // in trait checking. See `setup_constraining_predicates`
2321 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2322 let self_ty = tcx.type_of(def_id);
2323 let trait_ref = tcx.impl_trait_ref(def_id);
2324 cgp::setup_constraining_predicates(
2328 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2332 let result = ty::GenericPredicates {
2333 parent: generics.parent,
2334 predicates: tcx.arena.alloc_from_iter(predicates),
2336 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2340 fn const_evaluatable_predicates_of<'tcx>(
2343 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2344 struct ConstCollector<'tcx> {
2346 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2349 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2350 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2351 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2352 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2353 if let ty::ConstKind::Unevaluated(uv) = ct.kind() {
2354 assert_eq!(uv.promoted, None);
2355 let span = self.tcx.hir().span(c.hir_id);
2357 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2358 .to_predicate(self.tcx),
2364 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2365 // Do not look into const param defaults,
2366 // these get checked when they are actually instantiated.
2368 // We do not want the following to error:
2370 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2371 // struct Bar<const N: usize>(Foo<N, 3>);
2375 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2376 let node = tcx.hir().get(hir_id);
2378 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2379 if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
2380 if let Some(of_trait) = &impl_.of_trait {
2381 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2382 collector.visit_trait_ref(of_trait);
2385 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2386 collector.visit_ty(impl_.self_ty);
2389 if let Some(generics) = node.generics() {
2390 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2391 collector.visit_generics(generics);
2394 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2395 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2396 collector.visit_fn_decl(fn_sig.decl);
2398 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2403 fn trait_explicit_predicates_and_bounds(
2406 ) -> ty::GenericPredicates<'_> {
2407 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2408 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2411 fn explicit_predicates_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::GenericPredicates<'tcx> {
2412 let def_kind = tcx.def_kind(def_id);
2413 if let DefKind::Trait = def_kind {
2414 // Remove bounds on associated types from the predicates, they will be
2415 // returned by `explicit_item_bounds`.
2416 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2417 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2419 let is_assoc_item_ty = |ty: Ty<'tcx>| {
2420 // For a predicate from a where clause to become a bound on an
2422 // * It must use the identity substs of the item.
2423 // * Since any generic parameters on the item are not in scope,
2424 // this means that the item is not a GAT, and its identity
2425 // substs are the same as the trait's.
2426 // * It must be an associated type for this trait (*not* a
2428 if let ty::Projection(projection) = ty.kind() {
2429 projection.substs == trait_identity_substs
2430 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2436 let predicates: Vec<_> = predicates_and_bounds
2440 .filter(|(pred, _)| match pred.kind().skip_binder() {
2441 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2442 ty::PredicateKind::Projection(proj) => {
2443 !is_assoc_item_ty(proj.projection_ty.self_ty())
2445 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2449 if predicates.len() == predicates_and_bounds.predicates.len() {
2450 predicates_and_bounds
2452 ty::GenericPredicates {
2453 parent: predicates_and_bounds.parent,
2454 predicates: tcx.arena.alloc_slice(&predicates),
2458 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2459 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2460 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2461 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2462 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2463 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2465 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2466 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2467 // ^^^ explicit_predicates_of on
2468 // parent item we dont have set as the
2469 // parent of generics returned by `generics_of`
2471 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2472 let item_def_id = tcx.hir().get_parent_item(hir_id);
2473 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2474 return tcx.explicit_predicates_of(item_def_id);
2477 gather_explicit_predicates_of(tcx, def_id)
2481 /// Converts a specific `GenericBound` from the AST into a set of
2482 /// predicates that apply to the self type. A vector is returned
2483 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2484 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2485 /// and `<T as Bar>::X == i32`).
2486 fn predicates_from_bound<'tcx>(
2487 astconv: &dyn AstConv<'tcx>,
2489 bound: &'tcx hir::GenericBound<'tcx>,
2490 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2491 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2492 let mut bounds = Bounds::default();
2493 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2494 bounds.predicates(astconv.tcx(), param_ty).collect()
2497 fn compute_sig_of_foreign_fn_decl<'tcx>(
2500 decl: &'tcx hir::FnDecl<'tcx>,
2502 ) -> ty::PolyFnSig<'tcx> {
2503 let unsafety = if abi == abi::Abi::RustIntrinsic {
2504 intrinsic_operation_unsafety(tcx.item_name(def_id))
2506 hir::Unsafety::Unsafe
2508 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2509 let fty = <dyn AstConv<'_>>::ty_of_fn(
2510 &ItemCtxt::new(tcx, def_id),
2519 // Feature gate SIMD types in FFI, since I am not sure that the
2520 // ABIs are handled at all correctly. -huonw
2521 if abi != abi::Abi::RustIntrinsic
2522 && abi != abi::Abi::PlatformIntrinsic
2523 && !tcx.features().simd_ffi
2525 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2530 .span_to_snippet(ast_ty.span)
2531 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2536 "use of SIMD type{} in FFI is highly experimental and \
2537 may result in invalid code",
2541 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2545 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2548 if let hir::FnRetTy::Return(ref ty) = decl.output {
2549 check(ty, fty.output().skip_binder())
2556 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2557 match tcx.hir().get_if_local(def_id) {
2558 Some(Node::ForeignItem(..)) => true,
2560 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2564 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2565 match tcx.hir().get_if_local(def_id) {
2566 Some(Node::Expr(&rustc_hir::Expr {
2567 kind: rustc_hir::ExprKind::Closure { body, .. },
2569 })) => tcx.hir().body(body).generator_kind(),
2571 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2575 fn from_target_feature(
2577 attr: &ast::Attribute,
2578 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2579 target_features: &mut Vec<Symbol>,
2581 let Some(list) = attr.meta_item_list() else { return };
2582 let bad_item = |span| {
2583 let msg = "malformed `target_feature` attribute input";
2584 let code = "enable = \"..\"";
2586 .struct_span_err(span, msg)
2587 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2590 let rust_features = tcx.features();
2592 // Only `enable = ...` is accepted in the meta-item list.
2593 if !item.has_name(sym::enable) {
2594 bad_item(item.span());
2598 // Must be of the form `enable = "..."` (a string).
2599 let Some(value) = item.value_str() else {
2600 bad_item(item.span());
2604 // We allow comma separation to enable multiple features.
2605 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2606 let Some(feature_gate) = supported_target_features.get(feature) else {
2608 format!("the feature named `{}` is not valid for this target", feature);
2609 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2612 format!("`{}` is not valid for this target", feature),
2614 if let Some(stripped) = feature.strip_prefix('+') {
2615 let valid = supported_target_features.contains_key(stripped);
2617 err.help("consider removing the leading `+` in the feature name");
2624 // Only allow features whose feature gates have been enabled.
2625 let allowed = match feature_gate.as_ref().copied() {
2626 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2627 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2628 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2629 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2630 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2631 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2632 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2633 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2634 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2635 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2636 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2637 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2638 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2639 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2640 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2641 Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
2642 Some(name) => bug!("unknown target feature gate {}", name),
2647 &tcx.sess.parse_sess,
2648 feature_gate.unwrap(),
2650 &format!("the target feature `{}` is currently unstable", feature),
2654 Some(Symbol::intern(feature))
2659 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage {
2660 use rustc_middle::mir::mono::Linkage::*;
2662 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2663 // applicable to variable declarations and may not really make sense for
2664 // Rust code in the first place but allow them anyway and trust that the
2665 // user knows what they're doing. Who knows, unanticipated use cases may pop
2666 // up in the future.
2668 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2669 // and don't have to be, LLVM treats them as no-ops.
2671 "appending" => Appending,
2672 "available_externally" => AvailableExternally,
2674 "extern_weak" => ExternalWeak,
2675 "external" => External,
2676 "internal" => Internal,
2677 "linkonce" => LinkOnceAny,
2678 "linkonce_odr" => LinkOnceODR,
2679 "private" => Private,
2681 "weak_odr" => WeakODR,
2682 _ => tcx.sess.span_fatal(tcx.def_span(def_id), "invalid linkage specified"),
2686 fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
2687 if cfg!(debug_assertions) {
2688 let def_kind = tcx.def_kind(did);
2690 def_kind.has_codegen_attrs(),
2691 "unexpected `def_kind` in `codegen_fn_attrs`: {def_kind:?}",
2695 let did = did.expect_local();
2696 let attrs = tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(did));
2697 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2698 if tcx.should_inherit_track_caller(did) {
2699 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2702 // The panic_no_unwind function called by TerminatorKind::Abort will never
2703 // unwind. If the panic handler that it invokes unwind then it will simply
2704 // call the panic handler again.
2705 if Some(did.to_def_id()) == tcx.lang_items().panic_no_unwind() {
2706 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2709 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2711 let mut inline_span = None;
2712 let mut link_ordinal_span = None;
2713 let mut no_sanitize_span = None;
2714 for attr in attrs.iter() {
2715 if attr.has_name(sym::cold) {
2716 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2717 } else if attr.has_name(sym::rustc_allocator) {
2718 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2719 } else if attr.has_name(sym::ffi_returns_twice) {
2720 if tcx.is_foreign_item(did) {
2721 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2723 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2728 "`#[ffi_returns_twice]` may only be used on foreign functions"
2732 } else if attr.has_name(sym::ffi_pure) {
2733 if tcx.is_foreign_item(did) {
2734 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2735 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2740 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2744 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2747 // `#[ffi_pure]` is only allowed on foreign functions
2752 "`#[ffi_pure]` may only be used on foreign functions"
2756 } else if attr.has_name(sym::ffi_const) {
2757 if tcx.is_foreign_item(did) {
2758 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2760 // `#[ffi_const]` is only allowed on foreign functions
2765 "`#[ffi_const]` may only be used on foreign functions"
2769 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2770 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2771 } else if attr.has_name(sym::naked) {
2772 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2773 } else if attr.has_name(sym::no_mangle) {
2774 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2775 } else if attr.has_name(sym::no_coverage) {
2776 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2777 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2778 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2779 } else if attr.has_name(sym::used) {
2780 let inner = attr.meta_item_list();
2781 match inner.as_deref() {
2782 Some([item]) if item.has_name(sym::linker) => {
2783 if !tcx.features().used_with_arg {
2785 &tcx.sess.parse_sess,
2788 "`#[used(linker)]` is currently unstable",
2792 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2794 Some([item]) if item.has_name(sym::compiler) => {
2795 if !tcx.features().used_with_arg {
2797 &tcx.sess.parse_sess,
2800 "`#[used(compiler)]` is currently unstable",
2804 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2810 "expected `used`, `used(compiler)` or `used(linker)`",
2814 None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
2816 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2817 if !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. }) {
2822 "`#[cmse_nonsecure_entry]` requires C ABI"
2826 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2827 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2830 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2831 } else if attr.has_name(sym::thread_local) {
2832 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2833 } else if attr.has_name(sym::track_caller) {
2834 if !tcx.is_closure(did.to_def_id()) && tcx.fn_sig(did).abi() != abi::Abi::Rust {
2835 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2838 if tcx.is_closure(did.to_def_id()) && !tcx.features().closure_track_caller {
2840 &tcx.sess.parse_sess,
2841 sym::closure_track_caller,
2843 "`#[track_caller]` on closures is currently unstable",
2847 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2848 } else if attr.has_name(sym::export_name) {
2849 if let Some(s) = attr.value_str() {
2850 if s.as_str().contains('\0') {
2851 // `#[export_name = ...]` will be converted to a null-terminated string,
2852 // so it may not contain any null characters.
2857 "`export_name` may not contain null characters"
2861 codegen_fn_attrs.export_name = Some(s);
2863 } else if attr.has_name(sym::target_feature) {
2864 if !tcx.is_closure(did.to_def_id())
2865 && tcx.fn_sig(did).unsafety() == hir::Unsafety::Normal
2867 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2868 // The `#[target_feature]` attribute is allowed on
2869 // WebAssembly targets on all functions, including safe
2870 // ones. Other targets require that `#[target_feature]` is
2871 // only applied to unsafe functions (pending the
2872 // `target_feature_11` feature) because on most targets
2873 // execution of instructions that are not supported is
2874 // considered undefined behavior. For WebAssembly which is a
2875 // 100% safe target at execution time it's not possible to
2876 // execute undefined instructions, and even if a future
2877 // feature was added in some form for this it would be a
2878 // deterministic trap. There is no undefined behavior when
2879 // executing WebAssembly so `#[target_feature]` is allowed
2880 // on safe functions (but again, only for WebAssembly)
2882 // Note that this is also allowed if `actually_rustdoc` so
2883 // if a target is documenting some wasm-specific code then
2884 // it's not spuriously denied.
2885 } else if !tcx.features().target_feature_11 {
2886 let mut err = feature_err(
2887 &tcx.sess.parse_sess,
2888 sym::target_feature_11,
2890 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2892 err.span_label(tcx.def_span(did), "not an `unsafe` function");
2895 check_target_feature_trait_unsafe(tcx, did, attr.span);
2898 from_target_feature(
2901 supported_target_features,
2902 &mut codegen_fn_attrs.target_features,
2904 } else if attr.has_name(sym::linkage) {
2905 if let Some(val) = attr.value_str() {
2906 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, did, val.as_str()));
2908 } else if attr.has_name(sym::link_section) {
2909 if let Some(val) = attr.value_str() {
2910 if val.as_str().bytes().any(|b| b == 0) {
2912 "illegal null byte in link_section \
2916 tcx.sess.span_err(attr.span, &msg);
2918 codegen_fn_attrs.link_section = Some(val);
2921 } else if attr.has_name(sym::link_name) {
2922 codegen_fn_attrs.link_name = attr.value_str();
2923 } else if attr.has_name(sym::link_ordinal) {
2924 link_ordinal_span = Some(attr.span);
2925 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2926 codegen_fn_attrs.link_ordinal = ordinal;
2928 } else if attr.has_name(sym::no_sanitize) {
2929 no_sanitize_span = Some(attr.span);
2930 if let Some(list) = attr.meta_item_list() {
2931 for item in list.iter() {
2932 if item.has_name(sym::address) {
2933 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2934 } else if item.has_name(sym::cfi) {
2935 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2936 } else if item.has_name(sym::memory) {
2937 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2938 } else if item.has_name(sym::memtag) {
2939 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
2940 } else if item.has_name(sym::thread) {
2941 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2942 } else if item.has_name(sym::hwaddress) {
2943 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2946 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2947 .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, or `thread`")
2952 } else if attr.has_name(sym::instruction_set) {
2953 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
2954 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
2955 [NestedMetaItem::MetaItem(set)] => {
2957 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
2958 match segments.as_slice() {
2959 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
2960 if !tcx.sess.target.has_thumb_interworking {
2962 tcx.sess.diagnostic(),
2965 "target does not support `#[instruction_set]`"
2969 } else if segments[1] == sym::a32 {
2970 Some(InstructionSetAttr::ArmA32)
2971 } else if segments[1] == sym::t32 {
2972 Some(InstructionSetAttr::ArmT32)
2979 tcx.sess.diagnostic(),
2982 "invalid instruction set specified",
2991 tcx.sess.diagnostic(),
2994 "`#[instruction_set]` requires an argument"
3001 tcx.sess.diagnostic(),
3004 "cannot specify more than one instruction set"
3012 tcx.sess.diagnostic(),
3015 "must specify an instruction set"
3021 } else if attr.has_name(sym::repr) {
3022 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3023 Some(items) => match items.as_slice() {
3024 [item] => match item.name_value_literal() {
3025 Some((sym::align, literal)) => {
3026 let alignment = rustc_attr::parse_alignment(&literal.kind);
3029 Ok(align) => Some(align),
3032 tcx.sess.diagnostic(),
3035 "invalid `repr(align)` attribute: {}",
3054 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3055 if !attr.has_name(sym::inline) {
3058 match attr.meta_kind() {
3059 Some(MetaItemKind::Word) => InlineAttr::Hint,
3060 Some(MetaItemKind::List(ref items)) => {
3061 inline_span = Some(attr.span);
3062 if items.len() != 1 {
3064 tcx.sess.diagnostic(),
3067 "expected one argument"
3071 } else if list_contains_name(&items, sym::always) {
3073 } else if list_contains_name(&items, sym::never) {
3077 tcx.sess.diagnostic(),
3087 Some(MetaItemKind::NameValue(_)) => ia,
3092 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3093 if !attr.has_name(sym::optimize) {
3096 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3097 match attr.meta_kind() {
3098 Some(MetaItemKind::Word) => {
3099 err(attr.span, "expected one argument");
3102 Some(MetaItemKind::List(ref items)) => {
3103 inline_span = Some(attr.span);
3104 if items.len() != 1 {
3105 err(attr.span, "expected one argument");
3107 } else if list_contains_name(&items, sym::size) {
3109 } else if list_contains_name(&items, sym::speed) {
3112 err(items[0].span(), "invalid argument");
3116 Some(MetaItemKind::NameValue(_)) => ia,
3121 // #73631: closures inherit `#[target_feature]` annotations
3122 if tcx.features().target_feature_11 && tcx.is_closure(did.to_def_id()) {
3123 let owner_id = tcx.parent(did.to_def_id());
3126 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3129 // If a function uses #[target_feature] it can't be inlined into general
3130 // purpose functions as they wouldn't have the right target features
3131 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3133 if !codegen_fn_attrs.target_features.is_empty() {
3134 if codegen_fn_attrs.inline == InlineAttr::Always {
3135 if let Some(span) = inline_span {
3138 "cannot use `#[inline(always)]` with \
3139 `#[target_feature]`",
3145 if !codegen_fn_attrs.no_sanitize.is_empty() {
3146 if codegen_fn_attrs.inline == InlineAttr::Always {
3147 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3148 let hir_id = tcx.hir().local_def_id_to_hir_id(did);
3149 tcx.struct_span_lint_hir(
3150 lint::builtin::INLINE_NO_SANITIZE,
3154 lint.build("`no_sanitize` will have no effect after inlining")
3155 .span_note(inline_span, "inlining requested here")
3163 // Weak lang items have the same semantics as "std internal" symbols in the
3164 // sense that they're preserved through all our LTO passes and only
3165 // strippable by the linker.
3167 // Additionally weak lang items have predetermined symbol names.
3168 if tcx.is_weak_lang_item(did.to_def_id()) {
3169 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3171 if let Some(name) = weak_lang_items::link_name(attrs) {
3172 codegen_fn_attrs.export_name = Some(name);
3173 codegen_fn_attrs.link_name = Some(name);
3175 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3177 // Internal symbols to the standard library all have no_mangle semantics in
3178 // that they have defined symbol names present in the function name. This
3179 // also applies to weak symbols where they all have known symbol names.
3180 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3181 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3184 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3185 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3186 // intrinsic functions.
3187 if let Some(name) = &codegen_fn_attrs.link_name {
3188 if name.as_str().starts_with("llvm.") {
3189 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3196 /// Computes the set of target features used in a function for the purposes of
3197 /// inline assembly.
3198 fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx FxHashSet<Symbol> {
3199 let mut target_features = tcx.sess.target_features.clone();
3200 if tcx.def_kind(did).has_codegen_attrs() {
3201 let attrs = tcx.codegen_fn_attrs(did);
3202 target_features.extend(&attrs.target_features);
3203 match attrs.instruction_set {
3205 Some(InstructionSetAttr::ArmA32) => {
3206 target_features.remove(&sym::thumb_mode);
3208 Some(InstructionSetAttr::ArmT32) => {
3209 target_features.insert(sym::thumb_mode);
3214 tcx.arena.alloc(target_features)
3217 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3218 /// applied to the method prototype.
3219 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3220 if let Some(impl_item) = tcx.opt_associated_item(def_id)
3221 && let ty::AssocItemContainer::ImplContainer(_) = impl_item.container
3222 && let Some(trait_item) = impl_item.trait_item_def_id
3225 .codegen_fn_attrs(trait_item)
3227 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3233 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3234 use rustc_ast::{Lit, LitIntType, LitKind};
3235 let meta_item_list = attr.meta_item_list();
3236 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3237 let sole_meta_list = match meta_item_list {
3238 Some([item]) => item.literal(),
3241 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3242 .note("the attribute requires exactly one argument")
3248 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3249 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3250 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3251 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3252 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3254 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3255 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3256 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3257 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3258 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3259 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3260 // about LINK.EXE failing.)
3261 if *ordinal <= u16::MAX as u128 {
3262 Some(*ordinal as u16)
3264 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3266 .struct_span_err(attr.span, &msg)
3267 .note("the value may not exceed `u16::MAX`")
3273 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3274 .note("an unsuffixed integer value, e.g., `1`, is expected")
3280 fn check_link_name_xor_ordinal(
3282 codegen_fn_attrs: &CodegenFnAttrs,
3283 inline_span: Option<Span>,
3285 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3288 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3289 if let Some(span) = inline_span {
3290 tcx.sess.span_err(span, msg);
3296 /// Checks the function annotated with `#[target_feature]` is not a safe
3297 /// trait method implementation, reporting an error if it is.
3298 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3299 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3300 let node = tcx.hir().get(hir_id);
3301 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3302 let parent_id = tcx.hir().get_parent_item(hir_id);
3303 let parent_item = tcx.hir().expect_item(parent_id);
3304 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3308 "`#[target_feature(..)]` cannot be applied to safe trait method",
3310 .span_label(attr_span, "cannot be applied to safe trait method")
3311 .span_label(tcx.def_span(id), "not an `unsafe` function")