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, StashKey};
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().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
99 /// # `ItemCtxt` vs `FnCtxt`
101 /// `ItemCtxt` is primarily used to type-check item signatures and lower them
102 /// from HIR to their [`ty::Ty`] representation, which is exposed using [`AstConv`].
103 /// It's also used for the bodies of items like structs where the body (the fields)
104 /// are just signatures.
106 /// This is in contrast to [`FnCtxt`], which is used to type-check bodies of
107 /// functions, closures, and `const`s -- anywhere that expressions and statements show up.
109 /// An important thing to note is that `ItemCtxt` does no inference -- it has no [`InferCtxt`] --
110 /// while `FnCtxt` does do inference.
112 /// [`FnCtxt`]: crate::check::FnCtxt
113 /// [`InferCtxt`]: rustc_infer::infer::InferCtxt
115 /// # Trait predicates
117 /// `ItemCtxt` has information about the predicates that are defined
118 /// on the trait. Unfortunately, this predicate information is
119 /// available in various different forms at various points in the
120 /// process. So we can't just store a pointer to e.g., the AST or the
121 /// parsed ty form, we have to be more flexible. To this end, the
122 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
123 /// `get_type_parameter_bounds` requests, drawing the information from
124 /// the AST (`hir::Generics`), recursively.
125 pub struct ItemCtxt<'tcx> {
130 ///////////////////////////////////////////////////////////////////////////
133 pub(crate) struct HirPlaceholderCollector(pub(crate) Vec<Span>);
135 impl<'v> Visitor<'v> for HirPlaceholderCollector {
136 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
137 if let hir::TyKind::Infer = t.kind {
140 intravisit::walk_ty(self, t)
142 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
144 hir::GenericArg::Infer(inf) => {
145 self.0.push(inf.span);
146 intravisit::walk_inf(self, inf);
148 hir::GenericArg::Type(t) => self.visit_ty(t),
152 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
153 if let &hir::ArrayLen::Infer(_, span) = length {
156 intravisit::walk_array_len(self, length)
160 struct CollectItemTypesVisitor<'tcx> {
164 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
165 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
166 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
167 pub(crate) fn placeholder_type_error<'tcx>(
169 generics: Option<&hir::Generics<'_>>,
170 placeholder_types: Vec<Span>,
172 hir_ty: Option<&hir::Ty<'_>>,
175 if placeholder_types.is_empty() {
179 placeholder_type_error_diag(tcx, generics, placeholder_types, vec![], suggest, hir_ty, kind)
183 pub(crate) fn placeholder_type_error_diag<'tcx>(
185 generics: Option<&hir::Generics<'_>>,
186 placeholder_types: Vec<Span>,
187 additional_spans: Vec<Span>,
189 hir_ty: Option<&hir::Ty<'_>>,
191 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
192 if placeholder_types.is_empty() {
193 return bad_placeholder(tcx, additional_spans, kind);
196 let params = generics.map(|g| g.params).unwrap_or_default();
197 let type_name = params.next_type_param_name(None);
198 let mut sugg: Vec<_> =
199 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
201 if let Some(generics) = generics {
202 if let Some(arg) = params.iter().find(|arg| {
203 matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. }))
205 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
206 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
207 sugg.push((arg.span, (*type_name).to_string()));
208 } else if let Some(span) = generics.span_for_param_suggestion() {
209 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
210 sugg.push((span, format!(", {}", type_name)));
212 sugg.push((generics.span, format!("<{}>", type_name)));
217 bad_placeholder(tcx, placeholder_types.into_iter().chain(additional_spans).collect(), kind);
219 // Suggest, but only if it is not a function in const or static
221 let mut is_fn = false;
222 let mut is_const_or_static = false;
224 if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind {
227 // Check if parent is const or static
228 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
229 let parent_node = tcx.hir().get(parent_id);
231 is_const_or_static = matches!(
233 Node::Item(&hir::Item {
234 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
236 }) | Node::TraitItem(&hir::TraitItem {
237 kind: hir::TraitItemKind::Const(..),
239 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
243 // if function is wrapped around a const or static,
244 // then don't show the suggestion
245 if !(is_fn && is_const_or_static) {
246 err.multipart_suggestion(
247 "use type parameters instead",
249 Applicability::HasPlaceholders,
257 fn reject_placeholder_type_signatures_in_item<'tcx>(
259 item: &'tcx hir::Item<'tcx>,
261 let (generics, suggest) = match &item.kind {
262 hir::ItemKind::Union(_, generics)
263 | hir::ItemKind::Enum(_, generics)
264 | hir::ItemKind::TraitAlias(generics, _)
265 | hir::ItemKind::Trait(_, _, generics, ..)
266 | hir::ItemKind::Impl(hir::Impl { generics, .. })
267 | hir::ItemKind::Struct(_, generics) => (generics, true),
268 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
269 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
270 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
274 let mut visitor = HirPlaceholderCollector::default();
275 visitor.visit_item(item);
277 placeholder_type_error(tcx, Some(generics), visitor.0, suggest, None, item.kind.descr());
280 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
281 type NestedFilter = nested_filter::OnlyBodies;
283 fn nested_visit_map(&mut self) -> Self::Map {
287 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
288 convert_item(self.tcx, item.item_id());
289 reject_placeholder_type_signatures_in_item(self.tcx, item);
290 intravisit::walk_item(self, item);
293 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
294 for param in generics.params {
296 hir::GenericParamKind::Lifetime { .. } => {}
297 hir::GenericParamKind::Type { default: Some(_), .. } => {
298 let def_id = self.tcx.hir().local_def_id(param.hir_id);
299 self.tcx.ensure().type_of(def_id);
301 hir::GenericParamKind::Type { .. } => {}
302 hir::GenericParamKind::Const { default, .. } => {
303 let def_id = self.tcx.hir().local_def_id(param.hir_id);
304 self.tcx.ensure().type_of(def_id);
305 if let Some(default) = default {
306 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
307 // need to store default and type of default
308 self.tcx.ensure().type_of(default_def_id);
309 self.tcx.ensure().const_param_default(def_id);
314 intravisit::walk_generics(self, generics);
317 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
318 if let hir::ExprKind::Closure { .. } = expr.kind {
319 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
320 self.tcx.ensure().generics_of(def_id);
321 // We do not call `type_of` for closures here as that
322 // depends on typecheck and would therefore hide
323 // any further errors in case one typeck fails.
325 intravisit::walk_expr(self, expr);
328 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
329 convert_trait_item(self.tcx, trait_item.trait_item_id());
330 intravisit::walk_trait_item(self, trait_item);
333 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
334 convert_impl_item(self.tcx, impl_item.impl_item_id());
335 intravisit::walk_impl_item(self, impl_item);
339 ///////////////////////////////////////////////////////////////////////////
340 // Utility types and common code for the above passes.
342 fn bad_placeholder<'tcx>(
344 mut spans: Vec<Span>,
346 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
347 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
350 let mut err = struct_span_err!(
354 "the placeholder `_` is not allowed within types on item signatures for {}",
358 err.span_label(span, "not allowed in type signatures");
363 impl<'tcx> ItemCtxt<'tcx> {
364 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
365 ItemCtxt { tcx, item_def_id }
368 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
369 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
372 pub fn hir_id(&self) -> hir::HirId {
373 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
376 pub fn node(&self) -> hir::Node<'tcx> {
377 self.tcx.hir().get(self.hir_id())
381 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
382 fn tcx(&self) -> TyCtxt<'tcx> {
386 fn item_def_id(&self) -> Option<DefId> {
387 Some(self.item_def_id)
390 fn get_type_parameter_bounds(
395 ) -> ty::GenericPredicates<'tcx> {
396 self.tcx.at(span).type_param_predicates((
398 def_id.expect_local(),
403 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
407 fn allow_ty_infer(&self) -> bool {
411 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
412 self.tcx().ty_error_with_message(span, "bad placeholder type")
415 fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
416 let ty = self.tcx.fold_regions(ty, |r, _| match *r {
417 ty::ReErased => self.tcx.lifetimes.re_static,
420 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
423 fn projected_ty_from_poly_trait_ref(
427 item_segment: &hir::PathSegment<'_>,
428 poly_trait_ref: ty::PolyTraitRef<'tcx>,
430 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
431 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
439 self.tcx().mk_projection(item_def_id, item_substs)
441 // There are no late-bound regions; we can just ignore the binder.
442 let mut err = struct_span_err!(
446 "cannot use the associated type of a trait \
447 with uninferred generic parameters"
451 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
453 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
455 hir::ItemKind::Enum(_, generics)
456 | hir::ItemKind::Struct(_, generics)
457 | hir::ItemKind::Union(_, generics) => {
458 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
459 let (lt_sp, sugg) = match generics.params {
460 [] => (generics.span, format!("<{}>", lt_name)),
462 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
465 let suggestions = vec![
468 span.with_hi(item_segment.ident.span.lo()),
471 // Replace the existing lifetimes with a new named lifetime.
472 self.tcx.replace_late_bound_regions_uncached(
475 self.tcx.mk_region(ty::ReEarlyBound(
476 ty::EarlyBoundRegion {
479 name: Symbol::intern(<_name),
487 err.multipart_suggestion(
488 "use a fully qualified path with explicit lifetimes",
490 Applicability::MaybeIncorrect,
496 hir::Node::Item(hir::Item {
498 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
502 | hir::Node::ForeignItem(_)
503 | hir::Node::TraitItem(_)
504 | hir::Node::ImplItem(_) => {
505 err.span_suggestion_verbose(
506 span.with_hi(item_segment.ident.span.lo()),
507 "use a fully qualified path with inferred lifetimes",
510 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
511 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
513 Applicability::MaybeIncorrect,
519 self.tcx().ty_error()
523 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
524 // Types in item signatures are not normalized to avoid undue dependencies.
528 fn set_tainted_by_errors(&self) {
529 // There's no obvious place to track this, so just let it go.
532 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
533 // There's no place to record types from signatures?
537 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
538 fn get_new_lifetime_name<'tcx>(
540 poly_trait_ref: ty::PolyTraitRef<'tcx>,
541 generics: &hir::Generics<'tcx>,
543 let existing_lifetimes = tcx
544 .collect_referenced_late_bound_regions(&poly_trait_ref)
547 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
548 Some(name.as_str().to_string())
553 .chain(generics.params.iter().filter_map(|param| {
554 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
555 Some(param.name.ident().as_str().to_string())
560 .collect::<FxHashSet<String>>();
562 let a_to_z_repeat_n = |n| {
563 (b'a'..=b'z').map(move |c| {
564 let mut s = '\''.to_string();
565 s.extend(std::iter::repeat(char::from(c)).take(n));
570 // If all single char lifetime names are present, we wrap around and double the chars.
571 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
574 /// Returns the predicates defined on `item_def_id` of the form
575 /// `X: Foo` where `X` is the type parameter `def_id`.
576 #[instrument(level = "trace", skip(tcx))]
577 fn type_param_predicates(
579 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
580 ) -> ty::GenericPredicates<'_> {
583 // In the AST, bounds can derive from two places. Either
584 // written inline like `<T: Foo>` or in a where-clause like
587 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
588 let param_owner = tcx.hir().ty_param_owner(def_id);
589 let generics = tcx.generics_of(param_owner);
590 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
591 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
593 // Don't look for bounds where the type parameter isn't in scope.
594 let parent = if item_def_id == param_owner.to_def_id() {
597 tcx.generics_of(item_def_id).parent
600 let mut result = parent
602 let icx = ItemCtxt::new(tcx, parent);
603 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
605 .unwrap_or_default();
606 let mut extend = None;
608 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
609 let ast_generics = match tcx.hir().get(item_hir_id) {
610 Node::TraitItem(item) => &item.generics,
612 Node::ImplItem(item) => &item.generics,
614 Node::Item(item) => {
616 ItemKind::Fn(.., ref generics, _)
617 | ItemKind::Impl(hir::Impl { ref generics, .. })
618 | ItemKind::TyAlias(_, ref generics)
619 | ItemKind::OpaqueTy(OpaqueTy {
621 origin: hir::OpaqueTyOrigin::TyAlias,
624 | ItemKind::Enum(_, ref generics)
625 | ItemKind::Struct(_, ref generics)
626 | ItemKind::Union(_, ref generics) => generics,
627 ItemKind::Trait(_, _, ref generics, ..) => {
628 // Implied `Self: Trait` and supertrait bounds.
629 if param_id == item_hir_id {
630 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
632 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
640 Node::ForeignItem(item) => match item.kind {
641 ForeignItemKind::Fn(_, _, ref generics) => generics,
648 let icx = ItemCtxt::new(tcx, item_def_id);
649 let extra_predicates = extend.into_iter().chain(
650 icx.type_parameter_bounds_in_generics(
654 OnlySelfBounds(true),
658 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
659 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
664 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
668 impl<'tcx> ItemCtxt<'tcx> {
669 /// Finds bounds from `hir::Generics`. This requires scanning through the
670 /// AST. We do this to avoid having to convert *all* the bounds, which
671 /// would create artificial cycles. Instead, we can only convert the
672 /// bounds for a type parameter `X` if `X::Foo` is used.
673 #[instrument(level = "trace", skip(self, ast_generics))]
674 fn type_parameter_bounds_in_generics(
676 ast_generics: &'tcx hir::Generics<'tcx>,
677 param_id: hir::HirId,
679 only_self_bounds: OnlySelfBounds,
680 assoc_name: Option<Ident>,
681 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
682 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
683 trace!(?param_def_id);
687 .filter_map(|wp| match *wp {
688 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
692 let bt = if bp.is_param_bound(param_def_id) {
694 } else if !only_self_bounds.0 {
695 Some(self.to_ty(bp.bounded_ty))
699 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
701 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b, bvars))).filter(
702 |(_, b, _)| match assoc_name {
703 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
708 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars))
712 #[instrument(level = "trace", skip(self))]
713 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
715 hir::GenericBound::Trait(poly_trait_ref, _) => {
716 let trait_ref = &poly_trait_ref.trait_ref;
717 if let Some(trait_did) = trait_ref.trait_def_id() {
718 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
728 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
729 let it = tcx.hir().item(item_id);
730 debug!("convert: item {} with id {}", it.ident, it.hir_id());
731 let def_id = item_id.def_id;
734 // These don't define types.
735 hir::ItemKind::ExternCrate(_)
736 | hir::ItemKind::Use(..)
737 | hir::ItemKind::Macro(..)
738 | hir::ItemKind::Mod(_)
739 | hir::ItemKind::GlobalAsm(_) => {}
740 hir::ItemKind::ForeignMod { items, .. } => {
742 let item = tcx.hir().foreign_item(item.id);
743 tcx.ensure().generics_of(item.def_id);
744 tcx.ensure().type_of(item.def_id);
745 tcx.ensure().predicates_of(item.def_id);
747 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
748 hir::ForeignItemKind::Static(..) => {
749 let mut visitor = HirPlaceholderCollector::default();
750 visitor.visit_foreign_item(item);
751 placeholder_type_error(
764 hir::ItemKind::Enum(ref enum_definition, _) => {
765 tcx.ensure().generics_of(def_id);
766 tcx.ensure().type_of(def_id);
767 tcx.ensure().predicates_of(def_id);
768 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
770 hir::ItemKind::Impl { .. } => {
771 tcx.ensure().generics_of(def_id);
772 tcx.ensure().type_of(def_id);
773 tcx.ensure().impl_trait_ref(def_id);
774 tcx.ensure().predicates_of(def_id);
776 hir::ItemKind::Trait(..) => {
777 tcx.ensure().generics_of(def_id);
778 tcx.ensure().trait_def(def_id);
779 tcx.at(it.span).super_predicates_of(def_id);
780 tcx.ensure().predicates_of(def_id);
782 hir::ItemKind::TraitAlias(..) => {
783 tcx.ensure().generics_of(def_id);
784 tcx.at(it.span).super_predicates_of(def_id);
785 tcx.ensure().predicates_of(def_id);
787 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
788 tcx.ensure().generics_of(def_id);
789 tcx.ensure().type_of(def_id);
790 tcx.ensure().predicates_of(def_id);
792 for f in struct_def.fields() {
793 let def_id = tcx.hir().local_def_id(f.hir_id);
794 tcx.ensure().generics_of(def_id);
795 tcx.ensure().type_of(def_id);
796 tcx.ensure().predicates_of(def_id);
799 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
800 convert_variant_ctor(tcx, ctor_hir_id);
804 // Desugared from `impl Trait`, so visited by the function's return type.
805 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
806 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
810 // Don't call `type_of` on opaque types, since that depends on type
811 // checking function bodies. `check_item_type` ensures that it's called
813 hir::ItemKind::OpaqueTy(..) => {
814 tcx.ensure().generics_of(def_id);
815 tcx.ensure().predicates_of(def_id);
816 tcx.ensure().explicit_item_bounds(def_id);
818 hir::ItemKind::TyAlias(..)
819 | hir::ItemKind::Static(..)
820 | hir::ItemKind::Const(..)
821 | hir::ItemKind::Fn(..) => {
822 tcx.ensure().generics_of(def_id);
823 tcx.ensure().type_of(def_id);
824 tcx.ensure().predicates_of(def_id);
826 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
827 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
828 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
829 if !is_suggestable_infer_ty(ty) {
830 let mut visitor = HirPlaceholderCollector::default();
831 visitor.visit_item(it);
832 placeholder_type_error(tcx, None, visitor.0, false, None, it.kind.descr());
841 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
842 let trait_item = tcx.hir().trait_item(trait_item_id);
843 tcx.ensure().generics_of(trait_item_id.def_id);
845 match trait_item.kind {
846 hir::TraitItemKind::Fn(..) => {
847 tcx.ensure().type_of(trait_item_id.def_id);
848 tcx.ensure().fn_sig(trait_item_id.def_id);
851 hir::TraitItemKind::Const(.., Some(_)) => {
852 tcx.ensure().type_of(trait_item_id.def_id);
855 hir::TraitItemKind::Const(hir_ty, _) => {
856 tcx.ensure().type_of(trait_item_id.def_id);
857 // Account for `const C: _;`.
858 let mut visitor = HirPlaceholderCollector::default();
859 visitor.visit_trait_item(trait_item);
860 if !tcx.sess.diagnostic().has_stashed_diagnostic(hir_ty.span, StashKey::ItemNoType) {
861 placeholder_type_error(tcx, None, visitor.0, false, None, "constant");
865 hir::TraitItemKind::Type(_, Some(_)) => {
866 tcx.ensure().item_bounds(trait_item_id.def_id);
867 tcx.ensure().type_of(trait_item_id.def_id);
868 // Account for `type T = _;`.
869 let mut visitor = HirPlaceholderCollector::default();
870 visitor.visit_trait_item(trait_item);
871 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
874 hir::TraitItemKind::Type(_, None) => {
875 tcx.ensure().item_bounds(trait_item_id.def_id);
876 // #74612: Visit and try to find bad placeholders
877 // even if there is no concrete type.
878 let mut visitor = HirPlaceholderCollector::default();
879 visitor.visit_trait_item(trait_item);
881 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
885 tcx.ensure().predicates_of(trait_item_id.def_id);
888 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
889 let def_id = impl_item_id.def_id;
890 tcx.ensure().generics_of(def_id);
891 tcx.ensure().type_of(def_id);
892 tcx.ensure().predicates_of(def_id);
893 let impl_item = tcx.hir().impl_item(impl_item_id);
894 match impl_item.kind {
895 hir::ImplItemKind::Fn(..) => {
896 tcx.ensure().fn_sig(def_id);
898 hir::ImplItemKind::TyAlias(_) => {
899 // Account for `type T = _;`
900 let mut visitor = HirPlaceholderCollector::default();
901 visitor.visit_impl_item(impl_item);
903 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
905 hir::ImplItemKind::Const(..) => {}
909 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
910 let def_id = tcx.hir().local_def_id(ctor_id);
911 tcx.ensure().generics_of(def_id);
912 tcx.ensure().type_of(def_id);
913 tcx.ensure().predicates_of(def_id);
916 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
917 let def = tcx.adt_def(def_id);
918 let repr_type = def.repr().discr_type();
919 let initial = repr_type.initial_discriminant(tcx);
920 let mut prev_discr = None::<Discr<'_>>;
922 // fill the discriminant values and field types
923 for variant in variants {
924 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
926 if let Some(ref e) = variant.disr_expr {
927 let expr_did = tcx.hir().local_def_id(e.hir_id);
928 def.eval_explicit_discr(tcx, expr_did.to_def_id())
929 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
932 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
935 format!("overflowed on value after {}", prev_discr.unwrap()),
938 "explicitly set `{} = {}` if that is desired outcome",
939 variant.ident, wrapped_discr
944 .unwrap_or(wrapped_discr),
947 for f in variant.data.fields() {
948 let def_id = tcx.hir().local_def_id(f.hir_id);
949 tcx.ensure().generics_of(def_id);
950 tcx.ensure().type_of(def_id);
951 tcx.ensure().predicates_of(def_id);
954 // Convert the ctor, if any. This also registers the variant as
956 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
957 convert_variant_ctor(tcx, ctor_hir_id);
964 variant_did: Option<LocalDefId>,
965 ctor_did: Option<LocalDefId>,
967 discr: ty::VariantDiscr,
968 def: &hir::VariantData<'_>,
969 adt_kind: ty::AdtKind,
970 parent_did: LocalDefId,
971 ) -> ty::VariantDef {
972 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
977 let fid = tcx.hir().local_def_id(f.hir_id);
978 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
979 if let Some(prev_span) = dup_span {
980 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
986 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
989 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
992 let recovered = match def {
993 hir::VariantData::Struct(_, r) => *r,
998 variant_did.map(LocalDefId::to_def_id),
999 ctor_did.map(LocalDefId::to_def_id),
1002 CtorKind::from_hir(def),
1004 parent_did.to_def_id(),
1006 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1007 || variant_did.map_or(false, |variant_did| {
1008 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1013 fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
1016 let def_id = def_id.expect_local();
1017 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1018 let Node::Item(item) = tcx.hir().get(hir_id) else {
1022 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1023 let (kind, variants) = match item.kind {
1024 ItemKind::Enum(ref def, _) => {
1025 let mut distance_from_explicit = 0;
1030 let variant_did = Some(tcx.hir().local_def_id(v.id));
1032 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1034 let discr = if let Some(ref e) = v.disr_expr {
1035 distance_from_explicit = 0;
1036 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1038 ty::VariantDiscr::Relative(distance_from_explicit)
1040 distance_from_explicit += 1;
1055 (AdtKind::Enum, variants)
1057 ItemKind::Struct(ref def, _) => {
1058 let variant_did = None::<LocalDefId>;
1059 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1061 let variants = std::iter::once(convert_variant(
1066 ty::VariantDiscr::Relative(0),
1073 (AdtKind::Struct, variants)
1075 ItemKind::Union(ref def, _) => {
1076 let variant_did = None;
1077 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1079 let variants = std::iter::once(convert_variant(
1084 ty::VariantDiscr::Relative(0),
1091 (AdtKind::Union, variants)
1095 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1098 /// Ensures that the super-predicates of the trait with a `DefId`
1099 /// of `trait_def_id` are converted and stored. This also ensures that
1100 /// the transitive super-predicates are converted.
1101 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1102 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1103 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1106 /// Ensures that the super-predicates of the trait with a `DefId`
1107 /// of `trait_def_id` are converted and stored. This also ensures that
1108 /// the transitive super-predicates are converted.
1109 fn super_predicates_that_define_assoc_type(
1111 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1112 ) -> ty::GenericPredicates<'_> {
1114 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1115 trait_def_id, assoc_name
1117 if trait_def_id.is_local() {
1118 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1119 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1121 let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
1122 bug!("trait_node_id {} is not an item", trait_hir_id);
1125 let (generics, bounds) = match item.kind {
1126 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1127 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1128 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1131 let icx = ItemCtxt::new(tcx, trait_def_id);
1133 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1134 let self_param_ty = tcx.types.self_param;
1135 let superbounds1 = if let Some(assoc_name) = assoc_name {
1136 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1143 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1146 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1148 // Convert any explicit superbounds in the where-clause,
1149 // e.g., `trait Foo where Self: Bar`.
1150 // In the case of trait aliases, however, we include all bounds in the where-clause,
1151 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1152 // as one of its "superpredicates".
1153 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1154 let superbounds2 = icx.type_parameter_bounds_in_generics(
1158 OnlySelfBounds(!is_trait_alias),
1162 // Combine the two lists to form the complete set of superbounds:
1163 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1164 debug!(?superbounds);
1166 // Now require that immediate supertraits are converted,
1167 // which will, in turn, reach indirect supertraits.
1168 if assoc_name.is_none() {
1169 // Now require that immediate supertraits are converted,
1170 // which will, in turn, reach indirect supertraits.
1171 for &(pred, span) in superbounds {
1172 debug!("superbound: {:?}", pred);
1173 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1174 tcx.at(span).super_predicates_of(bound.def_id());
1179 ty::GenericPredicates { parent: None, predicates: superbounds }
1181 // if `assoc_name` is None, then the query should've been redirected to an
1182 // external provider
1183 assert!(assoc_name.is_some());
1184 tcx.super_predicates_of(trait_def_id)
1188 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1189 let item = tcx.hir().expect_item(def_id.expect_local());
1191 let (is_auto, unsafety, items) = match item.kind {
1192 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1193 (is_auto == hir::IsAuto::Yes, unsafety, items)
1195 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1196 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1199 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1200 if paren_sugar && !tcx.features().unboxed_closures {
1204 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1205 which traits can use parenthetical notation",
1207 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1211 let is_marker = tcx.has_attr(def_id, sym::marker);
1212 let skip_array_during_method_dispatch =
1213 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1214 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1215 ty::trait_def::TraitSpecializationKind::Marker
1216 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1217 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1219 ty::trait_def::TraitSpecializationKind::None
1221 let must_implement_one_of = tcx
1222 .get_attr(def_id, sym::rustc_must_implement_one_of)
1223 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1224 // and that they are all identifiers
1225 .and_then(|attr| match attr.meta_item_list() {
1226 Some(items) if items.len() < 2 => {
1230 "the `#[rustc_must_implement_one_of]` attribute must be \
1231 used with at least 2 args",
1237 Some(items) => items
1239 .map(|item| item.ident().ok_or(item.span()))
1240 .collect::<Result<Box<[_]>, _>>()
1243 .struct_span_err(span, "must be a name of an associated function")
1247 .zip(Some(attr.span)),
1248 // Error is reported by `rustc_attr!`
1251 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1252 // functions in the trait with default implementations
1253 .and_then(|(list, attr_span)| {
1254 let errors = list.iter().filter_map(|ident| {
1255 let item = items.iter().find(|item| item.ident == *ident);
1258 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1259 if !tcx.impl_defaultness(item.id.def_id).has_value() {
1263 "This function doesn't have a default implementation",
1265 .span_note(attr_span, "required by this annotation")
1275 .struct_span_err(item.span, "Not a function")
1276 .span_note(attr_span, "required by this annotation")
1278 "All `#[rustc_must_implement_one_of]` arguments \
1279 must be associated function names",
1285 .struct_span_err(ident.span, "Function not found in this trait")
1293 (errors.count() == 0).then_some(list)
1295 // Check for duplicates
1297 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1298 let mut no_dups = true;
1300 for ident in &*list {
1301 if let Some(dup) = set.insert(ident.name, ident.span) {
1303 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1305 "All `#[rustc_must_implement_one_of]` arguments \
1314 no_dups.then_some(list)
1323 skip_array_during_method_dispatch,
1325 must_implement_one_of,
1329 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1330 struct LateBoundRegionsDetector<'tcx> {
1332 outer_index: ty::DebruijnIndex,
1333 has_late_bound_regions: Option<Span>,
1336 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1337 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1338 if self.has_late_bound_regions.is_some() {
1342 hir::TyKind::BareFn(..) => {
1343 self.outer_index.shift_in(1);
1344 intravisit::walk_ty(self, ty);
1345 self.outer_index.shift_out(1);
1347 _ => intravisit::walk_ty(self, ty),
1351 fn visit_poly_trait_ref(&mut self, tr: &'tcx hir::PolyTraitRef<'tcx>) {
1352 if self.has_late_bound_regions.is_some() {
1355 self.outer_index.shift_in(1);
1356 intravisit::walk_poly_trait_ref(self, tr);
1357 self.outer_index.shift_out(1);
1360 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1361 if self.has_late_bound_regions.is_some() {
1365 match self.tcx.named_region(lt.hir_id) {
1366 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1367 Some(rl::Region::LateBound(debruijn, _, _)) if debruijn < self.outer_index => {}
1368 Some(rl::Region::LateBound(..) | rl::Region::Free(..)) | None => {
1369 self.has_late_bound_regions = Some(lt.span);
1375 fn has_late_bound_regions<'tcx>(
1377 generics: &'tcx hir::Generics<'tcx>,
1378 decl: &'tcx hir::FnDecl<'tcx>,
1380 let mut visitor = LateBoundRegionsDetector {
1382 outer_index: ty::INNERMOST,
1383 has_late_bound_regions: None,
1385 for param in generics.params {
1386 if let GenericParamKind::Lifetime { .. } = param.kind {
1387 if tcx.is_late_bound(param.hir_id) {
1388 return Some(param.span);
1392 visitor.visit_fn_decl(decl);
1393 visitor.has_late_bound_regions
1397 Node::TraitItem(item) => match item.kind {
1398 hir::TraitItemKind::Fn(ref sig, _) => {
1399 has_late_bound_regions(tcx, &item.generics, sig.decl)
1403 Node::ImplItem(item) => match item.kind {
1404 hir::ImplItemKind::Fn(ref sig, _) => {
1405 has_late_bound_regions(tcx, &item.generics, sig.decl)
1409 Node::ForeignItem(item) => match item.kind {
1410 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1411 has_late_bound_regions(tcx, generics, fn_decl)
1415 Node::Item(item) => match item.kind {
1416 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1417 has_late_bound_regions(tcx, generics, sig.decl)
1425 struct AnonConstInParamTyDetector {
1427 found_anon_const_in_param_ty: bool,
1431 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1432 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1433 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1434 let prev = self.in_param_ty;
1435 self.in_param_ty = true;
1437 self.in_param_ty = prev;
1441 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1442 if self.in_param_ty && self.ct == c.hir_id {
1443 self.found_anon_const_in_param_ty = true;
1445 intravisit::walk_anon_const(self, c)
1450 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1453 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1455 let node = tcx.hir().get(hir_id);
1456 let parent_def_id = match node {
1458 | Node::TraitItem(_)
1461 | Node::Field(_) => {
1462 let parent_id = tcx.hir().get_parent_item(hir_id);
1463 Some(parent_id.to_def_id())
1465 // FIXME(#43408) always enable this once `lazy_normalization` is
1466 // stable enough and does not need a feature gate anymore.
1467 Node::AnonConst(_) => {
1468 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1470 let mut in_param_ty = false;
1471 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1472 if let Some(generics) = node.generics() {
1473 let mut visitor = AnonConstInParamTyDetector {
1475 found_anon_const_in_param_ty: false,
1479 visitor.visit_generics(generics);
1480 in_param_ty = visitor.found_anon_const_in_param_ty;
1486 // We do not allow generic parameters in anon consts if we are inside
1487 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1489 } else if tcx.lazy_normalization() {
1490 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1491 // If the def_id we are calling generics_of on is an anon ct default i.e:
1493 // struct Foo<const N: usize = { .. }>;
1494 // ^^^ ^ ^^^^^^ def id of this anon const
1498 // then we only want to return generics for params to the left of `N`. If we don't do that we
1499 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1501 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1502 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1503 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1505 // We fix this by having this function return the parent's generics ourselves and truncating the
1506 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1508 // For the above code example that means we want `substs: []`
1509 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1510 // the def id of the `{ N + 1 }` anon const
1511 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1513 // This has some implications for how we get the predicates available to the anon const
1514 // see `explicit_predicates_of` for more information on this
1515 let generics = tcx.generics_of(parent_def_id.to_def_id());
1516 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1517 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1518 // In the above example this would be .params[..N#0]
1519 let params = generics.params[..param_def_idx as usize].to_owned();
1520 let param_def_id_to_index =
1521 params.iter().map(|param| (param.def_id, param.index)).collect();
1523 return ty::Generics {
1524 // we set the parent of these generics to be our parent's parent so that we
1525 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1526 // struct Foo<const N: usize, const M: usize = { ... }>;
1527 parent: generics.parent,
1528 parent_count: generics.parent_count,
1530 param_def_id_to_index,
1531 has_self: generics.has_self,
1532 has_late_bound_regions: generics.has_late_bound_regions,
1536 // HACK(eddyb) this provides the correct generics when
1537 // `feature(generic_const_expressions)` is enabled, so that const expressions
1538 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1540 // Note that we do not supply the parent generics when using
1541 // `min_const_generics`.
1542 Some(parent_def_id.to_def_id())
1544 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1546 // HACK(eddyb) this provides the correct generics for repeat
1547 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1548 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1549 // as they shouldn't be able to cause query cycle errors.
1550 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1551 if constant.hir_id() == hir_id =>
1553 Some(parent_def_id.to_def_id())
1555 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1556 if constant.hir_id == hir_id =>
1558 Some(parent_def_id.to_def_id())
1560 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1561 Some(tcx.typeck_root_def_id(def_id))
1563 // Exclude `GlobalAsm` here which cannot have generics.
1564 Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
1565 if asm.operands.iter().any(|(op, _op_sp)| match op {
1566 hir::InlineAsmOperand::Const { anon_const }
1567 | hir::InlineAsmOperand::SymFn { anon_const } => {
1568 anon_const.hir_id == hir_id
1573 Some(parent_def_id.to_def_id())
1579 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
1580 Some(tcx.typeck_root_def_id(def_id))
1582 Node::Item(item) => match item.kind {
1583 ItemKind::OpaqueTy(hir::OpaqueTy {
1585 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1590 assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn))
1592 assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn | DefKind::Fn))
1594 Some(fn_def_id.to_def_id())
1596 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1597 let parent_id = tcx.hir().get_parent_item(hir_id);
1598 assert_ne!(parent_id, CRATE_DEF_ID);
1599 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1600 // Opaque types are always nested within another item, and
1601 // inherit the generics of the item.
1602 Some(parent_id.to_def_id())
1612 FutureCompatDisallowed,
1616 let no_generics = hir::Generics::empty();
1617 let ast_generics = node.generics().unwrap_or(&no_generics);
1618 let (opt_self, allow_defaults) = match node {
1619 Node::Item(item) => {
1621 ItemKind::Trait(..) | ItemKind::TraitAlias(..) => {
1622 // Add in the self type parameter.
1624 // Something of a hack: use the node id for the trait, also as
1625 // the node id for the Self type parameter.
1626 let opt_self = Some(ty::GenericParamDef {
1628 name: kw::SelfUpper,
1630 pure_wrt_drop: false,
1631 kind: ty::GenericParamDefKind::Type {
1637 (opt_self, Defaults::Allowed)
1639 ItemKind::TyAlias(..)
1640 | ItemKind::Enum(..)
1641 | ItemKind::Struct(..)
1642 | ItemKind::OpaqueTy(..)
1643 | ItemKind::Union(..) => (None, Defaults::Allowed),
1644 _ => (None, Defaults::FutureCompatDisallowed),
1649 Node::TraitItem(item) if matches!(item.kind, TraitItemKind::Type(..)) => {
1650 (None, Defaults::Deny)
1652 Node::ImplItem(item) if matches!(item.kind, ImplItemKind::TyAlias(..)) => {
1653 (None, Defaults::Deny)
1656 _ => (None, Defaults::FutureCompatDisallowed),
1659 let has_self = opt_self.is_some();
1660 let mut parent_has_self = false;
1661 let mut own_start = has_self as u32;
1662 let parent_count = parent_def_id.map_or(0, |def_id| {
1663 let generics = tcx.generics_of(def_id);
1665 parent_has_self = generics.has_self;
1666 own_start = generics.count() as u32;
1667 generics.parent_count + generics.params.len()
1670 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1672 if let Some(opt_self) = opt_self {
1673 params.push(opt_self);
1676 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1677 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1678 name: param.name.ident().name,
1679 index: own_start + i as u32,
1680 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1681 pure_wrt_drop: param.pure_wrt_drop,
1682 kind: ty::GenericParamDefKind::Lifetime,
1685 // Now create the real type and const parameters.
1686 let type_start = own_start - has_self as u32 + params.len() as u32;
1689 const TYPE_DEFAULT_NOT_ALLOWED: &'static str = "defaults for type parameters are only allowed in \
1690 `struct`, `enum`, `type`, or `trait` definitions";
1692 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1693 GenericParamKind::Lifetime { .. } => None,
1694 GenericParamKind::Type { ref default, synthetic, .. } => {
1695 if default.is_some() {
1696 match allow_defaults {
1697 Defaults::Allowed => {}
1698 Defaults::FutureCompatDisallowed
1699 if tcx.features().default_type_parameter_fallback => {}
1700 Defaults::FutureCompatDisallowed => {
1701 tcx.struct_span_lint_hir(
1702 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1706 lint.build(TYPE_DEFAULT_NOT_ALLOWED).emit();
1711 tcx.sess.span_err(param.span, TYPE_DEFAULT_NOT_ALLOWED);
1716 let kind = ty::GenericParamDefKind::Type { has_default: default.is_some(), synthetic };
1718 let param_def = ty::GenericParamDef {
1719 index: type_start + i as u32,
1720 name: param.name.ident().name,
1721 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1722 pure_wrt_drop: param.pure_wrt_drop,
1728 GenericParamKind::Const { default, .. } => {
1729 if !matches!(allow_defaults, Defaults::Allowed) && default.is_some() {
1732 "defaults for const parameters are only allowed in \
1733 `struct`, `enum`, `type`, or `trait` definitions",
1737 let param_def = ty::GenericParamDef {
1738 index: type_start + i as u32,
1739 name: param.name.ident().name,
1740 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1741 pure_wrt_drop: param.pure_wrt_drop,
1742 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1749 // provide junk type parameter defs - the only place that
1750 // cares about anything but the length is instantiation,
1751 // and we don't do that for closures.
1752 if let Node::Expr(&hir::Expr {
1753 kind: hir::ExprKind::Closure(hir::Closure { movability: gen, .. }),
1757 let dummy_args = if gen.is_some() {
1758 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1760 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1763 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1764 index: type_start + i as u32,
1765 name: Symbol::intern(arg),
1767 pure_wrt_drop: false,
1768 kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false },
1772 // provide junk type parameter defs for const blocks.
1773 if let Node::AnonConst(_) = node {
1774 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1775 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1776 params.push(ty::GenericParamDef {
1778 name: Symbol::intern("<const_ty>"),
1780 pure_wrt_drop: false,
1781 kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false },
1786 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1789 parent: parent_def_id,
1792 param_def_id_to_index,
1793 has_self: has_self || parent_has_self,
1794 has_late_bound_regions: has_late_bound_regions(tcx, node),
1798 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1799 generic_args.iter().any(|arg| match arg {
1800 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1801 hir::GenericArg::Infer(_) => true,
1806 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1807 /// use inference to provide suggestions for the appropriate type if possible.
1808 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1813 Slice(ty) => is_suggestable_infer_ty(ty),
1814 Array(ty, length) => {
1815 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1817 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1818 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1819 OpaqueDef(_, generic_args, _) => are_suggestable_generic_args(generic_args),
1820 Path(hir::QPath::TypeRelative(ty, segment)) => {
1821 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1823 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1824 ty_opt.map_or(false, is_suggestable_infer_ty)
1825 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1831 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1832 if let hir::FnRetTy::Return(ty) = output {
1833 if is_suggestable_infer_ty(ty) {
1840 #[instrument(level = "debug", skip(tcx))]
1841 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1842 use rustc_hir::Node::*;
1845 let def_id = def_id.expect_local();
1846 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1848 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1850 match tcx.hir().get(hir_id) {
1851 TraitItem(hir::TraitItem {
1852 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1856 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => {
1857 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1860 ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => {
1861 // Do not try to inference the return type for a impl method coming from a trait
1862 if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) =
1863 tcx.hir().get(tcx.hir().get_parent_node(hir_id))
1864 && i.of_trait.is_some()
1866 <dyn AstConv<'_>>::ty_of_fn(
1869 sig.header.unsafety,
1876 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1880 TraitItem(hir::TraitItem {
1881 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1884 }) => <dyn AstConv<'_>>::ty_of_fn(
1894 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
1895 let abi = tcx.hir().get_foreign_abi(hir_id);
1896 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi)
1899 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1900 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1902 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1903 ty::Binder::dummy(tcx.mk_fn_sig(
1907 hir::Unsafety::Normal,
1912 Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
1913 // Closure signatures are not like other function
1914 // signatures and cannot be accessed through `fn_sig`. For
1915 // example, a closure signature excludes the `self`
1916 // argument. In any case they are embedded within the
1917 // closure type as part of the `ClosureSubsts`.
1919 // To get the signature of a closure, you should use the
1920 // `sig` method on the `ClosureSubsts`:
1922 // substs.as_closure().sig(def_id, tcx)
1924 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1929 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1934 fn infer_return_ty_for_fn_sig<'tcx>(
1936 sig: &hir::FnSig<'_>,
1937 generics: &hir::Generics<'_>,
1939 icx: &ItemCtxt<'tcx>,
1940 ) -> ty::PolyFnSig<'tcx> {
1941 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1943 match get_infer_ret_ty(&sig.decl.output) {
1945 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1946 // Typeck doesn't expect erased regions to be returned from `type_of`.
1947 let fn_sig = tcx.fold_regions(fn_sig, |r, _| match *r {
1948 ty::ReErased => tcx.lifetimes.re_static,
1951 let fn_sig = ty::Binder::dummy(fn_sig);
1953 let mut visitor = HirPlaceholderCollector::default();
1954 visitor.visit_ty(ty);
1955 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1956 let ret_ty = fn_sig.skip_binder().output();
1957 if ret_ty.is_suggestable(tcx, false) {
1958 diag.span_suggestion(
1960 "replace with the correct return type",
1962 Applicability::MachineApplicable,
1964 } else if matches!(ret_ty.kind(), ty::FnDef(..)) {
1965 let fn_sig = ret_ty.fn_sig(tcx);
1970 .all(|t| t.is_suggestable(tcx, false))
1972 diag.span_suggestion(
1974 "replace with the correct return type",
1976 Applicability::MachineApplicable,
1979 } else if ret_ty.is_closure() {
1980 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1981 // to prevent the user from getting a papercut while trying to use the unique closure
1982 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1983 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1984 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1990 None => <dyn AstConv<'_>>::ty_of_fn(
1993 sig.header.unsafety,
2002 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
2003 let icx = ItemCtxt::new(tcx, def_id);
2004 match tcx.hir().expect_item(def_id.expect_local()).kind {
2005 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
2006 let selfty = tcx.type_of(def_id);
2007 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
2013 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
2014 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
2015 let item = tcx.hir().expect_item(def_id.expect_local());
2017 hir::ItemKind::Impl(hir::Impl {
2018 polarity: hir::ImplPolarity::Negative(span),
2022 if is_rustc_reservation {
2023 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
2024 tcx.sess.span_err(span, "reservation impls can't be negative");
2026 ty::ImplPolarity::Negative
2028 hir::ItemKind::Impl(hir::Impl {
2029 polarity: hir::ImplPolarity::Positive,
2033 if is_rustc_reservation {
2034 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2036 ty::ImplPolarity::Positive
2038 hir::ItemKind::Impl(hir::Impl {
2039 polarity: hir::ImplPolarity::Positive,
2043 if is_rustc_reservation {
2044 ty::ImplPolarity::Reservation
2046 ty::ImplPolarity::Positive
2049 item => bug!("impl_polarity: {:?} not an impl", item),
2053 /// Returns the early-bound lifetimes declared in this generics
2054 /// listing. For anything other than fns/methods, this is just all
2055 /// the lifetimes that are declared. For fns or methods, we have to
2056 /// screen out those that do not appear in any where-clauses etc using
2057 /// `resolve_lifetime::early_bound_lifetimes`.
2058 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2060 generics: &'a hir::Generics<'a>,
2061 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2062 generics.params.iter().filter(move |param| match param.kind {
2063 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
2068 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2069 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2070 /// inferred constraints concerning which regions outlive other regions.
2071 #[instrument(level = "debug", skip(tcx))]
2072 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2073 let mut result = tcx.explicit_predicates_of(def_id);
2074 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2075 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2076 if !inferred_outlives.is_empty() {
2078 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2079 def_id, inferred_outlives,
2081 if result.predicates.is_empty() {
2082 result.predicates = inferred_outlives;
2084 result.predicates = tcx
2086 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2090 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2094 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2095 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2096 /// `Self: Trait` predicates for traits.
2097 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2098 let mut result = tcx.predicates_defined_on(def_id);
2100 if tcx.is_trait(def_id) {
2101 // For traits, add `Self: Trait` predicate. This is
2102 // not part of the predicates that a user writes, but it
2103 // is something that one must prove in order to invoke a
2104 // method or project an associated type.
2106 // In the chalk setup, this predicate is not part of the
2107 // "predicates" for a trait item. But it is useful in
2108 // rustc because if you directly (e.g.) invoke a trait
2109 // method like `Trait::method(...)`, you must naturally
2110 // prove that the trait applies to the types that were
2111 // used, and adding the predicate into this list ensures
2112 // that this is done.
2114 // We use a DUMMY_SP here as a way to signal trait bounds that come
2115 // from the trait itself that *shouldn't* be shown as the source of
2116 // an obligation and instead be skipped. Otherwise we'd use
2117 // `tcx.def_span(def_id);`
2119 let constness = if tcx.has_attr(def_id, sym::const_trait) {
2120 ty::BoundConstness::ConstIfConst
2122 ty::BoundConstness::NotConst
2125 let span = rustc_span::DUMMY_SP;
2127 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2128 ty::TraitRef::identity(tcx, def_id).with_constness(constness).to_predicate(tcx),
2132 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2136 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2137 /// N.B., this does not include any implied/inferred constraints.
2138 #[instrument(level = "trace", skip(tcx), ret)]
2139 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2142 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2143 let node = tcx.hir().get(hir_id);
2145 let mut is_trait = None;
2146 let mut is_default_impl_trait = None;
2148 let icx = ItemCtxt::new(tcx, def_id);
2150 const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
2152 // We use an `IndexSet` to preserves order of insertion.
2153 // Preserving the order of insertion is important here so as not to break UI tests.
2154 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2156 let ast_generics = match node {
2157 Node::TraitItem(item) => item.generics,
2159 Node::ImplItem(item) => item.generics,
2161 Node::Item(item) => {
2163 ItemKind::Impl(ref impl_) => {
2164 if impl_.defaultness.is_default() {
2165 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2169 ItemKind::Fn(.., ref generics, _)
2170 | ItemKind::TyAlias(_, ref generics)
2171 | ItemKind::Enum(_, ref generics)
2172 | ItemKind::Struct(_, ref generics)
2173 | ItemKind::Union(_, ref generics) => *generics,
2175 ItemKind::Trait(_, _, ref generics, ..) => {
2176 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2179 ItemKind::TraitAlias(ref generics, _) => {
2180 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2183 ItemKind::OpaqueTy(OpaqueTy {
2184 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2187 // return-position impl trait
2189 // We don't inherit predicates from the parent here:
2190 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2191 // then the return type is `f::<'static, T>::{{opaque}}`.
2193 // If we inherited the predicates of `f` then we would
2194 // require that `T: 'static` to show that the return
2195 // type is well-formed.
2197 // The only way to have something with this opaque type
2198 // is from the return type of the containing function,
2199 // which will ensure that the function's predicates
2201 return ty::GenericPredicates { parent: None, predicates: &[] };
2203 ItemKind::OpaqueTy(OpaqueTy {
2205 origin: hir::OpaqueTyOrigin::TyAlias,
2208 // type-alias impl trait
2216 Node::ForeignItem(item) => match item.kind {
2217 ForeignItemKind::Static(..) => NO_GENERICS,
2218 ForeignItemKind::Fn(_, _, ref generics) => *generics,
2219 ForeignItemKind::Type => NO_GENERICS,
2225 let generics = tcx.generics_of(def_id);
2226 let parent_count = generics.parent_count as u32;
2227 let has_own_self = generics.has_self && parent_count == 0;
2229 // Below we'll consider the bounds on the type parameters (including `Self`)
2230 // and the explicit where-clauses, but to get the full set of predicates
2231 // on a trait we need to add in the supertrait bounds and bounds found on
2232 // associated types.
2233 if let Some(_trait_ref) = is_trait {
2234 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2237 // In default impls, we can assume that the self type implements
2238 // the trait. So in:
2240 // default impl Foo for Bar { .. }
2242 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2243 // (see below). Recall that a default impl is not itself an impl, but rather a
2244 // set of defaults that can be incorporated into another impl.
2245 if let Some(trait_ref) = is_default_impl_trait {
2246 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2249 // Collect the region predicates that were declared inline as
2250 // well. In the case of parameters declared on a fn or method, we
2251 // have to be careful to only iterate over early-bound regions.
2252 let mut index = parent_count
2253 + has_own_self as u32
2254 + early_bound_lifetimes_from_generics(tcx, ast_generics).count() as u32;
2256 trace!(?predicates);
2257 trace!(?ast_generics);
2259 // Collect the predicates that were written inline by the user on each
2260 // type parameter (e.g., `<T: Foo>`).
2261 for param in ast_generics.params {
2263 // We already dealt with early bound lifetimes above.
2264 GenericParamKind::Lifetime { .. } => (),
2265 GenericParamKind::Type { .. } => {
2266 let name = param.name.ident().name;
2267 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2270 let mut bounds = Bounds::default();
2271 // Params are implicitly sized unless a `?Sized` bound is found
2272 <dyn AstConv<'_>>::add_implicitly_sized(
2276 Some((param.hir_id, ast_generics.predicates)),
2280 predicates.extend(bounds.predicates(tcx, param_ty));
2281 trace!(?predicates);
2283 GenericParamKind::Const { .. } => {
2284 // Bounds on const parameters are currently not possible.
2290 trace!(?predicates);
2291 // Add in the bounds that appear in the where-clause.
2292 for predicate in ast_generics.predicates {
2294 hir::WherePredicate::BoundPredicate(bound_pred) => {
2295 let ty = icx.to_ty(bound_pred.bounded_ty);
2296 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2298 // Keep the type around in a dummy predicate, in case of no bounds.
2299 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2300 // is still checked for WF.
2301 if bound_pred.bounds.is_empty() {
2302 if let ty::Param(_) = ty.kind() {
2303 // This is a `where T:`, which can be in the HIR from the
2304 // transformation that moves `?Sized` to `T`'s declaration.
2305 // We can skip the predicate because type parameters are
2306 // trivially WF, but also we *should*, to avoid exposing
2307 // users who never wrote `where Type:,` themselves, to
2308 // compiler/tooling bugs from not handling WF predicates.
2310 let span = bound_pred.bounded_ty.span;
2311 let predicate = ty::Binder::bind_with_vars(
2312 ty::PredicateKind::WellFormed(ty.into()),
2315 predicates.insert((predicate.to_predicate(tcx), span));
2319 let mut bounds = Bounds::default();
2320 <dyn AstConv<'_>>::add_bounds(
2323 bound_pred.bounds.iter(),
2327 predicates.extend(bounds.predicates(tcx, ty));
2330 hir::WherePredicate::RegionPredicate(region_pred) => {
2331 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2332 predicates.extend(region_pred.bounds.iter().map(|bound| {
2333 let (r2, span) = match bound {
2334 hir::GenericBound::Outlives(lt) => {
2335 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2339 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2340 ty::OutlivesPredicate(r1, r2),
2342 .to_predicate(icx.tcx);
2348 hir::WherePredicate::EqPredicate(..) => {
2354 if tcx.features().generic_const_exprs {
2355 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2358 let mut predicates: Vec<_> = predicates.into_iter().collect();
2360 // Subtle: before we store the predicates into the tcx, we
2361 // sort them so that predicates like `T: Foo<Item=U>` come
2362 // before uses of `U`. This avoids false ambiguity errors
2363 // in trait checking. See `setup_constraining_predicates`
2365 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2366 let self_ty = tcx.type_of(def_id);
2367 let trait_ref = tcx.impl_trait_ref(def_id);
2368 cgp::setup_constraining_predicates(
2372 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2376 ty::GenericPredicates {
2377 parent: generics.parent,
2378 predicates: tcx.arena.alloc_from_iter(predicates),
2382 fn const_evaluatable_predicates_of<'tcx>(
2385 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2386 struct ConstCollector<'tcx> {
2388 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2391 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2392 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2393 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2394 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2395 if let ty::ConstKind::Unevaluated(uv) = ct.kind() {
2396 assert_eq!(uv.promoted, ());
2397 let span = self.tcx.hir().span(c.hir_id);
2399 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv))
2400 .to_predicate(self.tcx),
2406 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2407 // Do not look into const param defaults,
2408 // these get checked when they are actually instantiated.
2410 // We do not want the following to error:
2412 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2413 // struct Bar<const N: usize>(Foo<N, 3>);
2417 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2418 let node = tcx.hir().get(hir_id);
2420 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2421 if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
2422 if let Some(of_trait) = &impl_.of_trait {
2423 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2424 collector.visit_trait_ref(of_trait);
2427 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2428 collector.visit_ty(impl_.self_ty);
2431 if let Some(generics) = node.generics() {
2432 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2433 collector.visit_generics(generics);
2436 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2437 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2438 collector.visit_fn_decl(fn_sig.decl);
2440 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2445 fn trait_explicit_predicates_and_bounds(
2448 ) -> ty::GenericPredicates<'_> {
2449 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2450 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2453 fn explicit_predicates_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::GenericPredicates<'tcx> {
2454 let def_kind = tcx.def_kind(def_id);
2455 if let DefKind::Trait = def_kind {
2456 // Remove bounds on associated types from the predicates, they will be
2457 // returned by `explicit_item_bounds`.
2458 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2459 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2461 let is_assoc_item_ty = |ty: Ty<'tcx>| {
2462 // For a predicate from a where clause to become a bound on an
2464 // * It must use the identity substs of the item.
2465 // * Since any generic parameters on the item are not in scope,
2466 // this means that the item is not a GAT, and its identity
2467 // substs are the same as the trait's.
2468 // * It must be an associated type for this trait (*not* a
2470 if let ty::Projection(projection) = ty.kind() {
2471 projection.substs == trait_identity_substs
2472 && tcx.associated_item(projection.item_def_id).container_id(tcx) == def_id
2478 let predicates: Vec<_> = predicates_and_bounds
2482 .filter(|(pred, _)| match pred.kind().skip_binder() {
2483 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2484 ty::PredicateKind::Projection(proj) => {
2485 !is_assoc_item_ty(proj.projection_ty.self_ty())
2487 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2491 if predicates.len() == predicates_and_bounds.predicates.len() {
2492 predicates_and_bounds
2494 ty::GenericPredicates {
2495 parent: predicates_and_bounds.parent,
2496 predicates: tcx.arena.alloc_slice(&predicates),
2500 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2501 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2502 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2503 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2504 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2505 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2507 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2508 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2509 // ^^^ explicit_predicates_of on
2510 // parent item we dont have set as the
2511 // parent of generics returned by `generics_of`
2513 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2514 let item_def_id = tcx.hir().get_parent_item(hir_id);
2515 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2516 return tcx.explicit_predicates_of(item_def_id);
2519 gather_explicit_predicates_of(tcx, def_id)
2523 /// Converts a specific `GenericBound` from the AST into a set of
2524 /// predicates that apply to the self type. A vector is returned
2525 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2526 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2527 /// and `<T as Bar>::X == i32`).
2528 fn predicates_from_bound<'tcx>(
2529 astconv: &dyn AstConv<'tcx>,
2531 bound: &'tcx hir::GenericBound<'tcx>,
2532 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2533 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2534 let mut bounds = Bounds::default();
2535 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2536 bounds.predicates(astconv.tcx(), param_ty).collect()
2539 fn compute_sig_of_foreign_fn_decl<'tcx>(
2542 decl: &'tcx hir::FnDecl<'tcx>,
2544 ) -> ty::PolyFnSig<'tcx> {
2545 let unsafety = if abi == abi::Abi::RustIntrinsic {
2546 intrinsic_operation_unsafety(tcx.item_name(def_id))
2548 hir::Unsafety::Unsafe
2550 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2551 let fty = <dyn AstConv<'_>>::ty_of_fn(
2552 &ItemCtxt::new(tcx, def_id),
2561 // Feature gate SIMD types in FFI, since I am not sure that the
2562 // ABIs are handled at all correctly. -huonw
2563 if abi != abi::Abi::RustIntrinsic
2564 && abi != abi::Abi::PlatformIntrinsic
2565 && !tcx.features().simd_ffi
2567 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2572 .span_to_snippet(ast_ty.span)
2573 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2578 "use of SIMD type{} in FFI is highly experimental and \
2579 may result in invalid code",
2583 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2587 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2590 if let hir::FnRetTy::Return(ref ty) = decl.output {
2591 check(ty, fty.output().skip_binder())
2598 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2599 match tcx.hir().get_if_local(def_id) {
2600 Some(Node::ForeignItem(..)) => true,
2602 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2606 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2607 match tcx.hir().get_if_local(def_id) {
2608 Some(Node::Expr(&rustc_hir::Expr {
2609 kind: rustc_hir::ExprKind::Closure(&rustc_hir::Closure { body, .. }),
2611 })) => tcx.hir().body(body).generator_kind(),
2613 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2617 fn from_target_feature(
2619 attr: &ast::Attribute,
2620 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2621 target_features: &mut Vec<Symbol>,
2623 let Some(list) = attr.meta_item_list() else { return };
2624 let bad_item = |span| {
2625 let msg = "malformed `target_feature` attribute input";
2626 let code = "enable = \"..\"";
2628 .struct_span_err(span, msg)
2629 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2632 let rust_features = tcx.features();
2634 // Only `enable = ...` is accepted in the meta-item list.
2635 if !item.has_name(sym::enable) {
2636 bad_item(item.span());
2640 // Must be of the form `enable = "..."` (a string).
2641 let Some(value) = item.value_str() else {
2642 bad_item(item.span());
2646 // We allow comma separation to enable multiple features.
2647 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2648 let Some(feature_gate) = supported_target_features.get(feature) else {
2650 format!("the feature named `{}` is not valid for this target", feature);
2651 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2654 format!("`{}` is not valid for this target", feature),
2656 if let Some(stripped) = feature.strip_prefix('+') {
2657 let valid = supported_target_features.contains_key(stripped);
2659 err.help("consider removing the leading `+` in the feature name");
2666 // Only allow features whose feature gates have been enabled.
2667 let allowed = match feature_gate.as_ref().copied() {
2668 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2669 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2670 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2671 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2672 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2673 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2674 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2675 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2676 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2677 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2678 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2679 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2680 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2681 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2682 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2683 Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
2684 Some(name) => bug!("unknown target feature gate {}", name),
2689 &tcx.sess.parse_sess,
2690 feature_gate.unwrap(),
2692 &format!("the target feature `{}` is currently unstable", feature),
2696 Some(Symbol::intern(feature))
2701 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage {
2702 use rustc_middle::mir::mono::Linkage::*;
2704 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2705 // applicable to variable declarations and may not really make sense for
2706 // Rust code in the first place but allow them anyway and trust that the
2707 // user knows what they're doing. Who knows, unanticipated use cases may pop
2708 // up in the future.
2710 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2711 // and don't have to be, LLVM treats them as no-ops.
2713 "appending" => Appending,
2714 "available_externally" => AvailableExternally,
2716 "extern_weak" => ExternalWeak,
2717 "external" => External,
2718 "internal" => Internal,
2719 "linkonce" => LinkOnceAny,
2720 "linkonce_odr" => LinkOnceODR,
2721 "private" => Private,
2723 "weak_odr" => WeakODR,
2724 _ => tcx.sess.span_fatal(tcx.def_span(def_id), "invalid linkage specified"),
2728 fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
2729 if cfg!(debug_assertions) {
2730 let def_kind = tcx.def_kind(did);
2732 def_kind.has_codegen_attrs(),
2733 "unexpected `def_kind` in `codegen_fn_attrs`: {def_kind:?}",
2737 let did = did.expect_local();
2738 let attrs = tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(did));
2739 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2740 if tcx.should_inherit_track_caller(did) {
2741 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2744 // The panic_no_unwind function called by TerminatorKind::Abort will never
2745 // unwind. If the panic handler that it invokes unwind then it will simply
2746 // call the panic handler again.
2747 if Some(did.to_def_id()) == tcx.lang_items().panic_no_unwind() {
2748 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2751 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2753 let mut inline_span = None;
2754 let mut link_ordinal_span = None;
2755 let mut no_sanitize_span = None;
2756 for attr in attrs.iter() {
2757 if attr.has_name(sym::cold) {
2758 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2759 } else if attr.has_name(sym::rustc_allocator) {
2760 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2761 } else if attr.has_name(sym::ffi_returns_twice) {
2762 if tcx.is_foreign_item(did) {
2763 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2765 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2770 "`#[ffi_returns_twice]` may only be used on foreign functions"
2774 } else if attr.has_name(sym::ffi_pure) {
2775 if tcx.is_foreign_item(did) {
2776 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2777 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2782 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2786 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2789 // `#[ffi_pure]` is only allowed on foreign functions
2794 "`#[ffi_pure]` may only be used on foreign functions"
2798 } else if attr.has_name(sym::ffi_const) {
2799 if tcx.is_foreign_item(did) {
2800 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2802 // `#[ffi_const]` is only allowed on foreign functions
2807 "`#[ffi_const]` may only be used on foreign functions"
2811 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2812 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2813 } else if attr.has_name(sym::rustc_reallocator) {
2814 codegen_fn_attrs.flags |= CodegenFnAttrFlags::REALLOCATOR;
2815 } else if attr.has_name(sym::rustc_deallocator) {
2816 codegen_fn_attrs.flags |= CodegenFnAttrFlags::DEALLOCATOR;
2817 } else if attr.has_name(sym::rustc_allocator_zeroed) {
2818 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR_ZEROED;
2819 } else if attr.has_name(sym::naked) {
2820 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2821 } else if attr.has_name(sym::no_mangle) {
2822 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2823 } else if attr.has_name(sym::no_coverage) {
2824 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2825 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2826 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2827 } else if attr.has_name(sym::used) {
2828 let inner = attr.meta_item_list();
2829 match inner.as_deref() {
2830 Some([item]) if item.has_name(sym::linker) => {
2831 if !tcx.features().used_with_arg {
2833 &tcx.sess.parse_sess,
2836 "`#[used(linker)]` is currently unstable",
2840 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2842 Some([item]) if item.has_name(sym::compiler) => {
2843 if !tcx.features().used_with_arg {
2845 &tcx.sess.parse_sess,
2848 "`#[used(compiler)]` is currently unstable",
2852 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2855 tcx.sess.emit_err(errors::ExpectedUsedSymbol { span: attr.span });
2858 // Unfortunately, unconditionally using `llvm.used` causes
2859 // issues in handling `.init_array` with the gold linker,
2860 // but using `llvm.compiler.used` caused a nontrival amount
2861 // of unintentional ecosystem breakage -- particularly on
2864 // As a result, we emit `llvm.compiler.used` only on ELF
2865 // targets. This is somewhat ad-hoc, but actually follows
2866 // our pre-LLVM 13 behavior (prior to the ecosystem
2867 // breakage), and seems to match `clang`'s behavior as well
2868 // (both before and after LLVM 13), possibly because they
2869 // have similar compatibility concerns to us. See
2870 // https://github.com/rust-lang/rust/issues/47384#issuecomment-1019080146
2871 // and following comments for some discussion of this, as
2872 // well as the comments in `rustc_codegen_llvm` where these
2873 // flags are handled.
2875 // Anyway, to be clear: this is still up in the air
2876 // somewhat, and is subject to change in the future (which
2877 // is a good thing, because this would ideally be a bit
2879 let is_like_elf = !(tcx.sess.target.is_like_osx
2880 || tcx.sess.target.is_like_windows
2881 || tcx.sess.target.is_like_wasm);
2882 codegen_fn_attrs.flags |= if is_like_elf {
2883 CodegenFnAttrFlags::USED
2885 CodegenFnAttrFlags::USED_LINKER
2889 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2890 if !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. }) {
2895 "`#[cmse_nonsecure_entry]` requires C ABI"
2899 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2900 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2903 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2904 } else if attr.has_name(sym::thread_local) {
2905 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2906 } else if attr.has_name(sym::track_caller) {
2907 if !tcx.is_closure(did.to_def_id()) && tcx.fn_sig(did).abi() != abi::Abi::Rust {
2908 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2911 if tcx.is_closure(did.to_def_id()) && !tcx.features().closure_track_caller {
2913 &tcx.sess.parse_sess,
2914 sym::closure_track_caller,
2916 "`#[track_caller]` on closures is currently unstable",
2920 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2921 } else if attr.has_name(sym::export_name) {
2922 if let Some(s) = attr.value_str() {
2923 if s.as_str().contains('\0') {
2924 // `#[export_name = ...]` will be converted to a null-terminated string,
2925 // so it may not contain any null characters.
2930 "`export_name` may not contain null characters"
2934 codegen_fn_attrs.export_name = Some(s);
2936 } else if attr.has_name(sym::target_feature) {
2937 if !tcx.is_closure(did.to_def_id())
2938 && tcx.fn_sig(did).unsafety() == hir::Unsafety::Normal
2940 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2941 // The `#[target_feature]` attribute is allowed on
2942 // WebAssembly targets on all functions, including safe
2943 // ones. Other targets require that `#[target_feature]` is
2944 // only applied to unsafe functions (pending the
2945 // `target_feature_11` feature) because on most targets
2946 // execution of instructions that are not supported is
2947 // considered undefined behavior. For WebAssembly which is a
2948 // 100% safe target at execution time it's not possible to
2949 // execute undefined instructions, and even if a future
2950 // feature was added in some form for this it would be a
2951 // deterministic trap. There is no undefined behavior when
2952 // executing WebAssembly so `#[target_feature]` is allowed
2953 // on safe functions (but again, only for WebAssembly)
2955 // Note that this is also allowed if `actually_rustdoc` so
2956 // if a target is documenting some wasm-specific code then
2957 // it's not spuriously denied.
2958 } else if !tcx.features().target_feature_11 {
2959 let mut err = feature_err(
2960 &tcx.sess.parse_sess,
2961 sym::target_feature_11,
2963 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2965 err.span_label(tcx.def_span(did), "not an `unsafe` function");
2968 check_target_feature_trait_unsafe(tcx, did, attr.span);
2971 from_target_feature(
2974 supported_target_features,
2975 &mut codegen_fn_attrs.target_features,
2977 } else if attr.has_name(sym::linkage) {
2978 if let Some(val) = attr.value_str() {
2979 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, did, val.as_str()));
2981 } else if attr.has_name(sym::link_section) {
2982 if let Some(val) = attr.value_str() {
2983 if val.as_str().bytes().any(|b| b == 0) {
2985 "illegal null byte in link_section \
2989 tcx.sess.span_err(attr.span, &msg);
2991 codegen_fn_attrs.link_section = Some(val);
2994 } else if attr.has_name(sym::link_name) {
2995 codegen_fn_attrs.link_name = attr.value_str();
2996 } else if attr.has_name(sym::link_ordinal) {
2997 link_ordinal_span = Some(attr.span);
2998 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2999 codegen_fn_attrs.link_ordinal = ordinal;
3001 } else if attr.has_name(sym::no_sanitize) {
3002 no_sanitize_span = Some(attr.span);
3003 if let Some(list) = attr.meta_item_list() {
3004 for item in list.iter() {
3005 if item.has_name(sym::address) {
3006 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
3007 } else if item.has_name(sym::cfi) {
3008 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
3009 } else if item.has_name(sym::memory) {
3010 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
3011 } else if item.has_name(sym::memtag) {
3012 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
3013 } else if item.has_name(sym::shadow_call_stack) {
3014 codegen_fn_attrs.no_sanitize |= SanitizerSet::SHADOWCALLSTACK;
3015 } else if item.has_name(sym::thread) {
3016 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
3017 } else if item.has_name(sym::hwaddress) {
3018 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
3021 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
3022 .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, `shadow-call-stack`, or `thread`")
3027 } else if attr.has_name(sym::instruction_set) {
3028 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
3029 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
3030 [NestedMetaItem::MetaItem(set)] => {
3032 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
3033 match segments.as_slice() {
3034 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3035 if !tcx.sess.target.has_thumb_interworking {
3037 tcx.sess.diagnostic(),
3040 "target does not support `#[instruction_set]`"
3044 } else if segments[1] == sym::a32 {
3045 Some(InstructionSetAttr::ArmA32)
3046 } else if segments[1] == sym::t32 {
3047 Some(InstructionSetAttr::ArmT32)
3054 tcx.sess.diagnostic(),
3057 "invalid instruction set specified",
3066 tcx.sess.diagnostic(),
3069 "`#[instruction_set]` requires an argument"
3076 tcx.sess.diagnostic(),
3079 "cannot specify more than one instruction set"
3087 tcx.sess.diagnostic(),
3090 "must specify an instruction set"
3096 } else if attr.has_name(sym::repr) {
3097 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3098 Some(items) => match items.as_slice() {
3099 [item] => match item.name_value_literal() {
3100 Some((sym::align, literal)) => {
3101 let alignment = rustc_attr::parse_alignment(&literal.kind);
3104 Ok(align) => Some(align),
3107 tcx.sess.diagnostic(),
3110 "invalid `repr(align)` attribute: {}",
3129 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3130 if !attr.has_name(sym::inline) {
3133 match attr.meta_kind() {
3134 Some(MetaItemKind::Word) => InlineAttr::Hint,
3135 Some(MetaItemKind::List(ref items)) => {
3136 inline_span = Some(attr.span);
3137 if items.len() != 1 {
3139 tcx.sess.diagnostic(),
3142 "expected one argument"
3146 } else if list_contains_name(&items, sym::always) {
3148 } else if list_contains_name(&items, sym::never) {
3152 tcx.sess.diagnostic(),
3157 .help("valid inline arguments are `always` and `never`")
3163 Some(MetaItemKind::NameValue(_)) => ia,
3168 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3169 if !attr.has_name(sym::optimize) {
3172 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3173 match attr.meta_kind() {
3174 Some(MetaItemKind::Word) => {
3175 err(attr.span, "expected one argument");
3178 Some(MetaItemKind::List(ref items)) => {
3179 inline_span = Some(attr.span);
3180 if items.len() != 1 {
3181 err(attr.span, "expected one argument");
3183 } else if list_contains_name(&items, sym::size) {
3185 } else if list_contains_name(&items, sym::speed) {
3188 err(items[0].span(), "invalid argument");
3192 Some(MetaItemKind::NameValue(_)) => ia,
3197 // #73631: closures inherit `#[target_feature]` annotations
3198 if tcx.features().target_feature_11 && tcx.is_closure(did.to_def_id()) {
3199 let owner_id = tcx.parent(did.to_def_id());
3200 if tcx.def_kind(owner_id).has_codegen_attrs() {
3203 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied());
3207 // If a function uses #[target_feature] it can't be inlined into general
3208 // purpose functions as they wouldn't have the right target features
3209 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3211 if !codegen_fn_attrs.target_features.is_empty() {
3212 if codegen_fn_attrs.inline == InlineAttr::Always {
3213 if let Some(span) = inline_span {
3216 "cannot use `#[inline(always)]` with \
3217 `#[target_feature]`",
3223 if !codegen_fn_attrs.no_sanitize.is_empty() {
3224 if codegen_fn_attrs.inline == InlineAttr::Always {
3225 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3226 let hir_id = tcx.hir().local_def_id_to_hir_id(did);
3227 tcx.struct_span_lint_hir(
3228 lint::builtin::INLINE_NO_SANITIZE,
3232 lint.build("`no_sanitize` will have no effect after inlining")
3233 .span_note(inline_span, "inlining requested here")
3241 // Weak lang items have the same semantics as "std internal" symbols in the
3242 // sense that they're preserved through all our LTO passes and only
3243 // strippable by the linker.
3245 // Additionally weak lang items have predetermined symbol names.
3246 if tcx.is_weak_lang_item(did.to_def_id()) {
3247 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3249 if let Some(name) = weak_lang_items::link_name(attrs) {
3250 codegen_fn_attrs.export_name = Some(name);
3251 codegen_fn_attrs.link_name = Some(name);
3253 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3255 // Internal symbols to the standard library all have no_mangle semantics in
3256 // that they have defined symbol names present in the function name. This
3257 // also applies to weak symbols where they all have known symbol names.
3258 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3259 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3262 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3263 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3264 // intrinsic functions.
3265 if let Some(name) = &codegen_fn_attrs.link_name {
3266 if name.as_str().starts_with("llvm.") {
3267 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3274 /// Computes the set of target features used in a function for the purposes of
3275 /// inline assembly.
3276 fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx FxHashSet<Symbol> {
3277 let mut target_features = tcx.sess.unstable_target_features.clone();
3278 if tcx.def_kind(did).has_codegen_attrs() {
3279 let attrs = tcx.codegen_fn_attrs(did);
3280 target_features.extend(&attrs.target_features);
3281 match attrs.instruction_set {
3283 Some(InstructionSetAttr::ArmA32) => {
3284 target_features.remove(&sym::thumb_mode);
3286 Some(InstructionSetAttr::ArmT32) => {
3287 target_features.insert(sym::thumb_mode);
3292 tcx.arena.alloc(target_features)
3295 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3296 /// applied to the method prototype.
3297 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3298 if let Some(impl_item) = tcx.opt_associated_item(def_id)
3299 && let ty::AssocItemContainer::ImplContainer = impl_item.container
3300 && let Some(trait_item) = impl_item.trait_item_def_id
3303 .codegen_fn_attrs(trait_item)
3305 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3311 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3312 use rustc_ast::{Lit, LitIntType, LitKind};
3313 if !tcx.features().raw_dylib && tcx.sess.target.arch == "x86" {
3315 &tcx.sess.parse_sess,
3318 "`#[link_ordinal]` is unstable on x86",
3322 let meta_item_list = attr.meta_item_list();
3323 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3324 let sole_meta_list = match meta_item_list {
3325 Some([item]) => item.literal(),
3328 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3329 .note("the attribute requires exactly one argument")
3335 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3336 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3337 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3338 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3339 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3341 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3342 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3343 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3344 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3345 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3346 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3347 // about LINK.EXE failing.)
3348 if *ordinal <= u16::MAX as u128 {
3349 Some(*ordinal as u16)
3351 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3353 .struct_span_err(attr.span, &msg)
3354 .note("the value may not exceed `u16::MAX`")
3360 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3361 .note("an unsuffixed integer value, e.g., `1`, is expected")
3367 fn check_link_name_xor_ordinal(
3369 codegen_fn_attrs: &CodegenFnAttrs,
3370 inline_span: Option<Span>,
3372 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3375 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3376 if let Some(span) = inline_span {
3377 tcx.sess.span_err(span, msg);
3383 /// Checks the function annotated with `#[target_feature]` is not a safe
3384 /// trait method implementation, reporting an error if it is.
3385 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3386 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3387 let node = tcx.hir().get(hir_id);
3388 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3389 let parent_id = tcx.hir().get_parent_item(hir_id);
3390 let parent_item = tcx.hir().expect_item(parent_id);
3391 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3395 "`#[target_feature(..)]` cannot be applied to safe trait method",
3397 .span_label(attr_span, "cannot be applied to safe trait method")
3398 .span_label(tcx.def_span(id), "not an `unsafe` function")