1 // ignore-tidy-filelength
2 //! "Collection" is the process of determining the type and other external
3 //! details of each item in Rust. Collection is specifically concerned
4 //! with *inter-procedural* things -- for example, for a function
5 //! definition, collection will figure out the type and signature of the
6 //! function, but it will not visit the *body* of the function in any way,
7 //! nor examine type annotations on local variables (that's the job of
10 //! Collecting is ultimately defined by a bundle of queries that
11 //! inquire after various facts about the items in the crate (e.g.,
12 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
15 //! At present, however, we do run collection across all items in the
16 //! crate as a kind of pass. This should eventually be factored away.
18 use crate::astconv::AstConv;
19 use crate::bounds::Bounds;
20 use crate::check::intrinsic::intrinsic_operation_unsafety;
21 use crate::constrained_generic_params as cgp;
23 use crate::middle::resolve_lifetime as rl;
25 use rustc_ast::{MetaItemKind, NestedMetaItem};
26 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
27 use rustc_data_structures::captures::Captures;
28 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
29 use rustc_errors::{struct_span_err, Applicability};
31 use rustc_hir::def::{CtorKind, DefKind};
32 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
33 use rustc_hir::intravisit::{self, Visitor};
34 use rustc_hir::weak_lang_items;
35 use rustc_hir::{GenericParamKind, HirId, Node};
36 use rustc_middle::hir::nested_filter;
37 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
38 use rustc_middle::mir::mono::Linkage;
39 use rustc_middle::ty::query::Providers;
40 use rustc_middle::ty::subst::InternalSubsts;
41 use rustc_middle::ty::util::Discr;
42 use rustc_middle::ty::util::IntTypeExt;
43 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
44 use rustc_middle::ty::{ReprOptions, ToPredicate, TypeFoldable};
45 use rustc_session::lint;
46 use rustc_session::parse::feature_err;
47 use rustc_span::symbol::{kw, sym, Ident, Symbol};
48 use rustc_span::{Span, DUMMY_SP};
49 use rustc_target::spec::{abi, PanicStrategy, SanitizerSet};
50 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
56 struct OnlySelfBounds(bool);
58 ///////////////////////////////////////////////////////////////////////////
61 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
62 tcx.hir().visit_item_likes_in_module(
64 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
68 pub fn provide(providers: &mut Providers) {
69 *providers = Providers {
70 opt_const_param_of: type_of::opt_const_param_of,
71 type_of: type_of::type_of,
72 item_bounds: item_bounds::item_bounds,
73 explicit_item_bounds: item_bounds::explicit_item_bounds,
76 predicates_defined_on,
77 explicit_predicates_of,
79 super_predicates_that_define_assoc_type,
80 trait_explicit_predicates_and_bounds,
81 type_param_predicates,
91 collect_mod_item_types,
92 should_inherit_track_caller,
97 ///////////////////////////////////////////////////////////////////////////
99 /// Context specific to some particular item. This is what implements
100 /// `AstConv`. It has information about the predicates that are defined
101 /// on the trait. Unfortunately, this predicate information is
102 /// available in various different forms at various points in the
103 /// process. So we can't just store a pointer to e.g., the AST or the
104 /// parsed ty form, we have to be more flexible. To this end, the
105 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
106 /// `get_type_parameter_bounds` requests, drawing the information from
107 /// the AST (`hir::Generics`), recursively.
108 pub struct ItemCtxt<'tcx> {
113 ///////////////////////////////////////////////////////////////////////////
116 crate struct HirPlaceholderCollector(crate Vec<Span>);
118 impl<'v> Visitor<'v> for HirPlaceholderCollector {
119 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
120 if let hir::TyKind::Infer = t.kind {
123 intravisit::walk_ty(self, t)
125 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
127 hir::GenericArg::Infer(inf) => {
128 self.0.push(inf.span);
129 intravisit::walk_inf(self, inf);
131 hir::GenericArg::Type(t) => self.visit_ty(t),
135 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
136 if let &hir::ArrayLen::Infer(_, span) = length {
139 intravisit::walk_array_len(self, length)
143 struct CollectItemTypesVisitor<'tcx> {
147 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
148 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
149 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
150 crate fn placeholder_type_error<'tcx>(
153 generics: &[hir::GenericParam<'_>],
154 placeholder_types: Vec<Span>,
156 hir_ty: Option<&hir::Ty<'_>>,
159 if placeholder_types.is_empty() {
163 let type_name = generics.next_type_param_name(None);
164 let mut sugg: Vec<_> =
165 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
167 if generics.is_empty() {
168 if let Some(span) = span {
169 sugg.push((span, format!("<{}>", type_name)));
171 } else if let Some(arg) = generics
173 .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
175 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
176 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
177 sugg.push((arg.span, (*type_name).to_string()));
179 let last = generics.iter().last().unwrap();
180 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
181 let span = last.bounds_span_for_suggestions().unwrap_or(last.span.shrink_to_hi());
182 sugg.push((span, format!(", {}", type_name)));
185 let mut err = bad_placeholder(tcx, placeholder_types, kind);
187 // Suggest, but only if it is not a function in const or static
189 let mut is_fn = false;
190 let mut is_const_or_static = false;
192 if let Some(hir_ty) = hir_ty {
193 if let hir::TyKind::BareFn(_) = hir_ty.kind {
196 // Check if parent is const or static
197 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
198 let parent_node = tcx.hir().get(parent_id);
200 is_const_or_static = matches!(
202 Node::Item(&hir::Item {
203 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
205 }) | Node::TraitItem(&hir::TraitItem {
206 kind: hir::TraitItemKind::Const(..),
208 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
213 // if function is wrapped around a const or static,
214 // then don't show the suggestion
215 if !(is_fn && is_const_or_static) {
216 err.multipart_suggestion(
217 "use type parameters instead",
219 Applicability::HasPlaceholders,
226 fn reject_placeholder_type_signatures_in_item<'tcx>(
228 item: &'tcx hir::Item<'tcx>,
230 let (generics, suggest) = match &item.kind {
231 hir::ItemKind::Union(_, generics)
232 | hir::ItemKind::Enum(_, generics)
233 | hir::ItemKind::TraitAlias(generics, _)
234 | hir::ItemKind::Trait(_, _, generics, ..)
235 | hir::ItemKind::Impl(hir::Impl { generics, .. })
236 | hir::ItemKind::Struct(_, generics) => (generics, true),
237 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
238 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
239 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
243 let mut visitor = HirPlaceholderCollector::default();
244 visitor.visit_item(item);
246 placeholder_type_error(
257 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
258 type NestedFilter = nested_filter::OnlyBodies;
260 fn nested_visit_map(&mut self) -> Self::Map {
264 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
265 convert_item(self.tcx, item.item_id());
266 reject_placeholder_type_signatures_in_item(self.tcx, item);
267 intravisit::walk_item(self, item);
270 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
271 for param in generics.params {
273 hir::GenericParamKind::Lifetime { .. } => {}
274 hir::GenericParamKind::Type { default: Some(_), .. } => {
275 let def_id = self.tcx.hir().local_def_id(param.hir_id);
276 self.tcx.ensure().type_of(def_id);
278 hir::GenericParamKind::Type { .. } => {}
279 hir::GenericParamKind::Const { default, .. } => {
280 let def_id = self.tcx.hir().local_def_id(param.hir_id);
281 self.tcx.ensure().type_of(def_id);
282 if let Some(default) = default {
283 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
284 // need to store default and type of default
285 self.tcx.ensure().type_of(default_def_id);
286 self.tcx.ensure().const_param_default(def_id);
291 intravisit::walk_generics(self, generics);
294 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
295 if let hir::ExprKind::Closure(..) = expr.kind {
296 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
297 self.tcx.ensure().generics_of(def_id);
298 // We do not call `type_of` for closures here as that
299 // depends on typecheck and would therefore hide
300 // any further errors in case one typeck fails.
302 intravisit::walk_expr(self, expr);
305 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
306 convert_trait_item(self.tcx, trait_item.trait_item_id());
307 intravisit::walk_trait_item(self, trait_item);
310 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
311 convert_impl_item(self.tcx, impl_item.impl_item_id());
312 intravisit::walk_impl_item(self, impl_item);
316 ///////////////////////////////////////////////////////////////////////////
317 // Utility types and common code for the above passes.
319 fn bad_placeholder<'tcx>(
321 mut spans: Vec<Span>,
323 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
324 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
327 let mut err = struct_span_err!(
331 "the placeholder `_` is not allowed within types on item signatures for {}",
335 err.span_label(span, "not allowed in type signatures");
340 impl<'tcx> ItemCtxt<'tcx> {
341 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
342 ItemCtxt { tcx, item_def_id }
345 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
346 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
349 pub fn hir_id(&self) -> hir::HirId {
350 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
353 pub fn node(&self) -> hir::Node<'tcx> {
354 self.tcx.hir().get(self.hir_id())
358 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
359 fn tcx(&self) -> TyCtxt<'tcx> {
363 fn item_def_id(&self) -> Option<DefId> {
364 Some(self.item_def_id)
367 fn get_type_parameter_bounds(
372 ) -> ty::GenericPredicates<'tcx> {
373 self.tcx.at(span).type_param_predicates((
375 def_id.expect_local(),
380 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
384 fn allow_ty_infer(&self) -> bool {
388 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
389 self.tcx().ty_error_with_message(span, "bad placeholder type")
392 fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
393 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match *r {
394 ty::ReErased => self.tcx.lifetimes.re_static,
397 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
400 fn projected_ty_from_poly_trait_ref(
404 item_segment: &hir::PathSegment<'_>,
405 poly_trait_ref: ty::PolyTraitRef<'tcx>,
407 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
408 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
416 self.tcx().mk_projection(item_def_id, item_substs)
418 // There are no late-bound regions; we can just ignore the binder.
419 let mut err = struct_span_err!(
423 "cannot use the associated type of a trait \
424 with uninferred generic parameters"
428 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
430 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
432 hir::ItemKind::Enum(_, generics)
433 | hir::ItemKind::Struct(_, generics)
434 | hir::ItemKind::Union(_, generics) => {
435 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
436 let (lt_sp, sugg) = match generics.params {
437 [] => (generics.span, format!("<{}>", lt_name)),
439 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
442 let suggestions = vec![
445 span.with_hi(item_segment.ident.span.lo()),
448 // Replace the existing lifetimes with a new named lifetime.
450 .replace_late_bound_regions(poly_trait_ref, |_| {
451 self.tcx.mk_region(ty::ReEarlyBound(
452 ty::EarlyBoundRegion {
455 name: Symbol::intern(<_name),
463 err.multipart_suggestion(
464 "use a fully qualified path with explicit lifetimes",
466 Applicability::MaybeIncorrect,
472 hir::Node::Item(hir::Item {
474 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
478 | hir::Node::ForeignItem(_)
479 | hir::Node::TraitItem(_)
480 | hir::Node::ImplItem(_) => {
481 err.span_suggestion_verbose(
482 span.with_hi(item_segment.ident.span.lo()),
483 "use a fully qualified path with inferred lifetimes",
486 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
487 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
489 Applicability::MaybeIncorrect,
495 self.tcx().ty_error()
499 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
500 // Types in item signatures are not normalized to avoid undue dependencies.
504 fn set_tainted_by_errors(&self) {
505 // There's no obvious place to track this, so just let it go.
508 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
509 // There's no place to record types from signatures?
513 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
514 fn get_new_lifetime_name<'tcx>(
516 poly_trait_ref: ty::PolyTraitRef<'tcx>,
517 generics: &hir::Generics<'tcx>,
519 let existing_lifetimes = tcx
520 .collect_referenced_late_bound_regions(&poly_trait_ref)
523 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
524 Some(name.as_str().to_string())
529 .chain(generics.params.iter().filter_map(|param| {
530 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
531 Some(param.name.ident().as_str().to_string())
536 .collect::<FxHashSet<String>>();
538 let a_to_z_repeat_n = |n| {
539 (b'a'..=b'z').map(move |c| {
540 let mut s = '\''.to_string();
541 s.extend(std::iter::repeat(char::from(c)).take(n));
546 // If all single char lifetime names are present, we wrap around and double the chars.
547 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
550 /// Returns the predicates defined on `item_def_id` of the form
551 /// `X: Foo` where `X` is the type parameter `def_id`.
552 fn type_param_predicates(
554 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
555 ) -> ty::GenericPredicates<'_> {
558 // In the AST, bounds can derive from two places. Either
559 // written inline like `<T: Foo>` or in a where-clause like
562 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
563 let param_owner = tcx.hir().ty_param_owner(param_id);
564 let generics = tcx.generics_of(param_owner);
565 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
566 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
568 // Don't look for bounds where the type parameter isn't in scope.
569 let parent = if item_def_id == param_owner.to_def_id() {
572 tcx.generics_of(item_def_id).parent
575 let mut result = parent
577 let icx = ItemCtxt::new(tcx, parent);
578 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
580 .unwrap_or_default();
581 let mut extend = None;
583 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
584 let ast_generics = match tcx.hir().get(item_hir_id) {
585 Node::TraitItem(item) => &item.generics,
587 Node::ImplItem(item) => &item.generics,
589 Node::Item(item) => {
591 ItemKind::Fn(.., ref generics, _)
592 | ItemKind::Impl(hir::Impl { ref generics, .. })
593 | ItemKind::TyAlias(_, ref generics)
594 | ItemKind::OpaqueTy(OpaqueTy {
596 origin: hir::OpaqueTyOrigin::TyAlias,
599 | ItemKind::Enum(_, ref generics)
600 | ItemKind::Struct(_, ref generics)
601 | ItemKind::Union(_, ref generics) => generics,
602 ItemKind::Trait(_, _, ref generics, ..) => {
603 // Implied `Self: Trait` and supertrait bounds.
604 if param_id == item_hir_id {
605 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
607 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
615 Node::ForeignItem(item) => match item.kind {
616 ForeignItemKind::Fn(_, _, ref generics) => generics,
623 let icx = ItemCtxt::new(tcx, item_def_id);
624 let extra_predicates = extend.into_iter().chain(
625 icx.type_parameter_bounds_in_generics(
629 OnlySelfBounds(true),
633 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
634 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
639 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
643 impl<'tcx> ItemCtxt<'tcx> {
644 /// Finds bounds from `hir::Generics`. This requires scanning through the
645 /// AST. We do this to avoid having to convert *all* the bounds, which
646 /// would create artificial cycles. Instead, we can only convert the
647 /// bounds for a type parameter `X` if `X::Foo` is used.
648 fn type_parameter_bounds_in_generics(
650 ast_generics: &'tcx hir::Generics<'tcx>,
651 param_id: hir::HirId,
653 only_self_bounds: OnlySelfBounds,
654 assoc_name: Option<Ident>,
655 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
656 let from_ty_params = ast_generics
659 .filter_map(|param| match param.kind {
660 GenericParamKind::Type { .. } | GenericParamKind::Const { .. }
661 if param.hir_id == param_id =>
667 .flat_map(|bounds| bounds.iter())
668 .filter(|b| match assoc_name {
669 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
672 .flat_map(|b| predicates_from_bound(self, ty, b, ty::List::empty()));
674 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
675 let from_where_clauses = ast_generics
679 .filter_map(|wp| match *wp {
680 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
684 let bt = if bp.is_param_bound(param_def_id) {
686 } else if !only_self_bounds.0 {
687 Some(self.to_ty(bp.bounded_ty))
691 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
695 .filter(|b| match assoc_name {
696 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
699 .filter_map(move |b| bt.map(|bt| (bt, b, bvars)))
701 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars));
703 from_ty_params.chain(from_where_clauses).collect()
706 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
707 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
710 hir::GenericBound::Trait(poly_trait_ref, _) => {
711 let trait_ref = &poly_trait_ref.trait_ref;
712 if let Some(trait_did) = trait_ref.trait_def_id() {
713 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
723 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
724 let it = tcx.hir().item(item_id);
725 debug!("convert: item {} with id {}", it.ident, it.hir_id());
726 let def_id = item_id.def_id;
729 // These don't define types.
730 hir::ItemKind::ExternCrate(_)
731 | hir::ItemKind::Use(..)
732 | hir::ItemKind::Macro(_)
733 | hir::ItemKind::Mod(_)
734 | hir::ItemKind::GlobalAsm(_) => {}
735 hir::ItemKind::ForeignMod { items, .. } => {
737 let item = tcx.hir().foreign_item(item.id);
738 tcx.ensure().generics_of(item.def_id);
739 tcx.ensure().type_of(item.def_id);
740 tcx.ensure().predicates_of(item.def_id);
742 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
743 hir::ForeignItemKind::Static(..) => {
744 let mut visitor = HirPlaceholderCollector::default();
745 visitor.visit_foreign_item(item);
746 placeholder_type_error(
760 hir::ItemKind::Enum(ref enum_definition, _) => {
761 tcx.ensure().generics_of(def_id);
762 tcx.ensure().type_of(def_id);
763 tcx.ensure().predicates_of(def_id);
764 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
766 hir::ItemKind::Impl { .. } => {
767 tcx.ensure().generics_of(def_id);
768 tcx.ensure().type_of(def_id);
769 tcx.ensure().impl_trait_ref(def_id);
770 tcx.ensure().predicates_of(def_id);
772 hir::ItemKind::Trait(..) => {
773 tcx.ensure().generics_of(def_id);
774 tcx.ensure().trait_def(def_id);
775 tcx.at(it.span).super_predicates_of(def_id);
776 tcx.ensure().predicates_of(def_id);
778 hir::ItemKind::TraitAlias(..) => {
779 tcx.ensure().generics_of(def_id);
780 tcx.at(it.span).super_predicates_of(def_id);
781 tcx.ensure().predicates_of(def_id);
783 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
784 tcx.ensure().generics_of(def_id);
785 tcx.ensure().type_of(def_id);
786 tcx.ensure().predicates_of(def_id);
788 for f in struct_def.fields() {
789 let def_id = tcx.hir().local_def_id(f.hir_id);
790 tcx.ensure().generics_of(def_id);
791 tcx.ensure().type_of(def_id);
792 tcx.ensure().predicates_of(def_id);
795 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
796 convert_variant_ctor(tcx, ctor_hir_id);
800 // Desugared from `impl Trait`, so visited by the function's return type.
801 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
802 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
806 // Don't call `type_of` on opaque types, since that depends on type
807 // checking function bodies. `check_item_type` ensures that it's called
809 hir::ItemKind::OpaqueTy(..) => {
810 tcx.ensure().generics_of(def_id);
811 tcx.ensure().predicates_of(def_id);
812 tcx.ensure().explicit_item_bounds(def_id);
814 hir::ItemKind::TyAlias(..)
815 | hir::ItemKind::Static(..)
816 | hir::ItemKind::Const(..)
817 | hir::ItemKind::Fn(..) => {
818 tcx.ensure().generics_of(def_id);
819 tcx.ensure().type_of(def_id);
820 tcx.ensure().predicates_of(def_id);
822 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
823 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
824 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
825 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
826 if let hir::TyKind::TraitObject(..) = ty.kind {
827 let mut visitor = HirPlaceholderCollector::default();
828 visitor.visit_item(it);
829 placeholder_type_error(
846 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
847 let trait_item = tcx.hir().trait_item(trait_item_id);
848 tcx.ensure().generics_of(trait_item_id.def_id);
850 match trait_item.kind {
851 hir::TraitItemKind::Fn(..) => {
852 tcx.ensure().type_of(trait_item_id.def_id);
853 tcx.ensure().fn_sig(trait_item_id.def_id);
856 hir::TraitItemKind::Const(.., Some(_)) => {
857 tcx.ensure().type_of(trait_item_id.def_id);
860 hir::TraitItemKind::Const(..) => {
861 tcx.ensure().type_of(trait_item_id.def_id);
862 // Account for `const C: _;`.
863 let mut visitor = HirPlaceholderCollector::default();
864 visitor.visit_trait_item(trait_item);
865 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
868 hir::TraitItemKind::Type(_, Some(_)) => {
869 tcx.ensure().item_bounds(trait_item_id.def_id);
870 tcx.ensure().type_of(trait_item_id.def_id);
871 // Account for `type T = _;`.
872 let mut visitor = HirPlaceholderCollector::default();
873 visitor.visit_trait_item(trait_item);
874 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
877 hir::TraitItemKind::Type(_, None) => {
878 tcx.ensure().item_bounds(trait_item_id.def_id);
879 // #74612: Visit and try to find bad placeholders
880 // even if there is no concrete type.
881 let mut visitor = HirPlaceholderCollector::default();
882 visitor.visit_trait_item(trait_item);
884 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
888 tcx.ensure().predicates_of(trait_item_id.def_id);
891 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
892 let def_id = impl_item_id.def_id;
893 tcx.ensure().generics_of(def_id);
894 tcx.ensure().type_of(def_id);
895 tcx.ensure().predicates_of(def_id);
896 let impl_item = tcx.hir().impl_item(impl_item_id);
897 match impl_item.kind {
898 hir::ImplItemKind::Fn(..) => {
899 tcx.ensure().fn_sig(def_id);
901 hir::ImplItemKind::TyAlias(_) => {
902 // Account for `type T = _;`
903 let mut visitor = HirPlaceholderCollector::default();
904 visitor.visit_impl_item(impl_item);
906 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
908 hir::ImplItemKind::Const(..) => {}
912 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
913 let def_id = tcx.hir().local_def_id(ctor_id);
914 tcx.ensure().generics_of(def_id);
915 tcx.ensure().type_of(def_id);
916 tcx.ensure().predicates_of(def_id);
919 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
920 let def = tcx.adt_def(def_id);
921 let repr_type = def.repr.discr_type();
922 let initial = repr_type.initial_discriminant(tcx);
923 let mut prev_discr = None::<Discr<'_>>;
925 // fill the discriminant values and field types
926 for variant in variants {
927 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
929 if let Some(ref e) = variant.disr_expr {
930 let expr_did = tcx.hir().local_def_id(e.hir_id);
931 def.eval_explicit_discr(tcx, expr_did.to_def_id())
932 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
935 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
938 format!("overflowed on value after {}", prev_discr.unwrap()),
941 "explicitly set `{} = {}` if that is desired outcome",
942 variant.ident, wrapped_discr
947 .unwrap_or(wrapped_discr),
950 for f in variant.data.fields() {
951 let def_id = tcx.hir().local_def_id(f.hir_id);
952 tcx.ensure().generics_of(def_id);
953 tcx.ensure().type_of(def_id);
954 tcx.ensure().predicates_of(def_id);
957 // Convert the ctor, if any. This also registers the variant as
959 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
960 convert_variant_ctor(tcx, ctor_hir_id);
967 variant_did: Option<LocalDefId>,
968 ctor_did: Option<LocalDefId>,
970 discr: ty::VariantDiscr,
971 def: &hir::VariantData<'_>,
972 adt_kind: ty::AdtKind,
973 parent_did: LocalDefId,
974 ) -> ty::VariantDef {
975 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
980 let fid = tcx.hir().local_def_id(f.hir_id);
981 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
982 if let Some(prev_span) = dup_span {
983 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
989 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
992 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
995 let recovered = match def {
996 hir::VariantData::Struct(_, r) => *r,
1001 variant_did.map(LocalDefId::to_def_id),
1002 ctor_did.map(LocalDefId::to_def_id),
1005 CtorKind::from_hir(def),
1007 parent_did.to_def_id(),
1009 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1010 || variant_did.map_or(false, |variant_did| {
1011 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1016 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
1019 let def_id = def_id.expect_local();
1020 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1021 let item = match tcx.hir().get(hir_id) {
1022 Node::Item(item) => item,
1026 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1027 let (kind, variants) = match item.kind {
1028 ItemKind::Enum(ref def, _) => {
1029 let mut distance_from_explicit = 0;
1034 let variant_did = Some(tcx.hir().local_def_id(v.id));
1036 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1038 let discr = if let Some(ref e) = v.disr_expr {
1039 distance_from_explicit = 0;
1040 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1042 ty::VariantDiscr::Relative(distance_from_explicit)
1044 distance_from_explicit += 1;
1059 (AdtKind::Enum, variants)
1061 ItemKind::Struct(ref def, _) => {
1062 let variant_did = None::<LocalDefId>;
1063 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1065 let variants = std::iter::once(convert_variant(
1070 ty::VariantDiscr::Relative(0),
1077 (AdtKind::Struct, variants)
1079 ItemKind::Union(ref def, _) => {
1080 let variant_did = None;
1081 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1083 let variants = std::iter::once(convert_variant(
1088 ty::VariantDiscr::Relative(0),
1095 (AdtKind::Union, variants)
1099 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1102 /// Ensures that the super-predicates of the trait with a `DefId`
1103 /// of `trait_def_id` are converted and stored. This also ensures that
1104 /// the transitive super-predicates are converted.
1105 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1106 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1107 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1110 /// Ensures that the super-predicates of the trait with a `DefId`
1111 /// of `trait_def_id` are converted and stored. This also ensures that
1112 /// the transitive super-predicates are converted.
1113 fn super_predicates_that_define_assoc_type(
1115 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1116 ) -> ty::GenericPredicates<'_> {
1118 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1119 trait_def_id, assoc_name
1121 if trait_def_id.is_local() {
1122 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1123 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1125 let item = match tcx.hir().get(trait_hir_id) {
1126 Node::Item(item) => item,
1127 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
1130 let (generics, bounds) = match item.kind {
1131 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1132 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1133 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1136 let icx = ItemCtxt::new(tcx, trait_def_id);
1138 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1139 let self_param_ty = tcx.types.self_param;
1140 let superbounds1 = if let Some(assoc_name) = assoc_name {
1141 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1148 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1151 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1153 // Convert any explicit superbounds in the where-clause,
1154 // e.g., `trait Foo where Self: Bar`.
1155 // In the case of trait aliases, however, we include all bounds in the where-clause,
1156 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1157 // as one of its "superpredicates".
1158 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1159 let superbounds2 = icx.type_parameter_bounds_in_generics(
1163 OnlySelfBounds(!is_trait_alias),
1167 // Combine the two lists to form the complete set of superbounds:
1168 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1170 // Now require that immediate supertraits are converted,
1171 // which will, in turn, reach indirect supertraits.
1172 if assoc_name.is_none() {
1173 // Now require that immediate supertraits are converted,
1174 // which will, in turn, reach indirect supertraits.
1175 for &(pred, span) in superbounds {
1176 debug!("superbound: {:?}", pred);
1177 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1178 tcx.at(span).super_predicates_of(bound.def_id());
1183 ty::GenericPredicates { parent: None, predicates: superbounds }
1185 // if `assoc_name` is None, then the query should've been redirected to an
1186 // external provider
1187 assert!(assoc_name.is_some());
1188 tcx.super_predicates_of(trait_def_id)
1192 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1193 let item = tcx.hir().expect_item(def_id.expect_local());
1195 let (is_auto, unsafety, items) = match item.kind {
1196 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1197 (is_auto == hir::IsAuto::Yes, unsafety, items)
1199 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1200 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1203 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1204 if paren_sugar && !tcx.features().unboxed_closures {
1208 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1209 which traits can use parenthetical notation",
1211 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1215 let is_marker = tcx.has_attr(def_id, sym::marker);
1216 let skip_array_during_method_dispatch =
1217 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1218 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1219 ty::trait_def::TraitSpecializationKind::Marker
1220 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1221 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1223 ty::trait_def::TraitSpecializationKind::None
1225 let def_path_hash = tcx.def_path_hash(def_id);
1227 let must_implement_one_of = tcx
1230 .find(|attr| attr.has_name(sym::rustc_must_implement_one_of))
1231 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1232 // and that they are all identifiers
1233 .and_then(|attr| match attr.meta_item_list() {
1234 Some(items) if items.len() < 2 => {
1238 "the `#[rustc_must_implement_one_of]` attribute must be \
1239 used with at least 2 args",
1245 Some(items) => items
1247 .map(|item| item.ident().ok_or(item.span()))
1248 .collect::<Result<Box<[_]>, _>>()
1251 .struct_span_err(span, "must be a name of an associated function")
1255 .zip(Some(attr.span)),
1256 // Error is reported by `rustc_attr!`
1259 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1260 // functions in the trait with default implementations
1261 .and_then(|(list, attr_span)| {
1262 let errors = list.iter().filter_map(|ident| {
1263 let item = items.iter().find(|item| item.ident == *ident);
1266 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1267 if !item.defaultness.has_value() {
1271 "This function doesn't have a default implementation",
1273 .span_note(attr_span, "required by this annotation")
1283 .struct_span_err(item.span, "Not a function")
1284 .span_note(attr_span, "required by this annotation")
1286 "All `#[rustc_must_implement_one_of]` arguments \
1287 must be associated function names",
1292 .struct_span_err(ident.span, "Function not found in this trait")
1299 (errors.count() == 0).then_some(list)
1301 // Check for duplicates
1303 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1304 let mut no_dups = true;
1306 for ident in &*list {
1307 if let Some(dup) = set.insert(ident.name, ident.span) {
1309 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1311 "All `#[rustc_must_implement_one_of]` arguments \
1320 no_dups.then_some(list)
1329 skip_array_during_method_dispatch,
1332 must_implement_one_of,
1336 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1337 struct LateBoundRegionsDetector<'tcx> {
1339 outer_index: ty::DebruijnIndex,
1340 has_late_bound_regions: Option<Span>,
1343 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1344 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1345 if self.has_late_bound_regions.is_some() {
1349 hir::TyKind::BareFn(..) => {
1350 self.outer_index.shift_in(1);
1351 intravisit::walk_ty(self, ty);
1352 self.outer_index.shift_out(1);
1354 _ => intravisit::walk_ty(self, ty),
1358 fn visit_poly_trait_ref(
1360 tr: &'tcx hir::PolyTraitRef<'tcx>,
1361 m: hir::TraitBoundModifier,
1363 if self.has_late_bound_regions.is_some() {
1366 self.outer_index.shift_in(1);
1367 intravisit::walk_poly_trait_ref(self, tr, m);
1368 self.outer_index.shift_out(1);
1371 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1372 if self.has_late_bound_regions.is_some() {
1376 match self.tcx.named_region(lt.hir_id) {
1377 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1379 rl::Region::LateBound(debruijn, _, _, _)
1380 | rl::Region::LateBoundAnon(debruijn, _, _),
1381 ) if debruijn < self.outer_index => {}
1383 rl::Region::LateBound(..)
1384 | rl::Region::LateBoundAnon(..)
1385 | rl::Region::Free(..),
1388 self.has_late_bound_regions = Some(lt.span);
1394 fn has_late_bound_regions<'tcx>(
1396 generics: &'tcx hir::Generics<'tcx>,
1397 decl: &'tcx hir::FnDecl<'tcx>,
1399 let mut visitor = LateBoundRegionsDetector {
1401 outer_index: ty::INNERMOST,
1402 has_late_bound_regions: None,
1404 for param in generics.params {
1405 if let GenericParamKind::Lifetime { .. } = param.kind {
1406 if tcx.is_late_bound(param.hir_id) {
1407 return Some(param.span);
1411 visitor.visit_fn_decl(decl);
1412 visitor.has_late_bound_regions
1416 Node::TraitItem(item) => match item.kind {
1417 hir::TraitItemKind::Fn(ref sig, _) => {
1418 has_late_bound_regions(tcx, &item.generics, sig.decl)
1422 Node::ImplItem(item) => match item.kind {
1423 hir::ImplItemKind::Fn(ref sig, _) => {
1424 has_late_bound_regions(tcx, &item.generics, sig.decl)
1428 Node::ForeignItem(item) => match item.kind {
1429 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1430 has_late_bound_regions(tcx, generics, fn_decl)
1434 Node::Item(item) => match item.kind {
1435 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1436 has_late_bound_regions(tcx, generics, sig.decl)
1444 struct AnonConstInParamTyDetector {
1446 found_anon_const_in_param_ty: bool,
1450 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1451 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1452 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1453 let prev = self.in_param_ty;
1454 self.in_param_ty = true;
1456 self.in_param_ty = prev;
1460 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1461 if self.in_param_ty && self.ct == c.hir_id {
1462 self.found_anon_const_in_param_ty = true;
1464 intravisit::walk_anon_const(self, c)
1469 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1472 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1474 let node = tcx.hir().get(hir_id);
1475 let parent_def_id = match node {
1477 | Node::TraitItem(_)
1480 | Node::Field(_) => {
1481 let parent_id = tcx.hir().get_parent_item(hir_id);
1482 Some(parent_id.to_def_id())
1484 // FIXME(#43408) always enable this once `lazy_normalization` is
1485 // stable enough and does not need a feature gate anymore.
1486 Node::AnonConst(_) => {
1487 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1489 let mut in_param_ty = false;
1490 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1491 if let Some(generics) = node.generics() {
1492 let mut visitor = AnonConstInParamTyDetector {
1494 found_anon_const_in_param_ty: false,
1498 visitor.visit_generics(generics);
1499 in_param_ty = visitor.found_anon_const_in_param_ty;
1505 // We do not allow generic parameters in anon consts if we are inside
1506 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1508 } else if tcx.lazy_normalization() {
1509 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1510 // If the def_id we are calling generics_of on is an anon ct default i.e:
1512 // struct Foo<const N: usize = { .. }>;
1513 // ^^^ ^ ^^^^^^ def id of this anon const
1517 // then we only want to return generics for params to the left of `N`. If we don't do that we
1518 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1520 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1521 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1522 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1524 // We fix this by having this function return the parent's generics ourselves and truncating the
1525 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1527 // For the above code example that means we want `substs: []`
1528 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1529 // the def id of the `{ N + 1 }` anon const
1530 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1532 // This has some implications for how we get the predicates available to the anon const
1533 // see `explicit_predicates_of` for more information on this
1534 let generics = tcx.generics_of(parent_def_id.to_def_id());
1535 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1536 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1537 // In the above example this would be .params[..N#0]
1538 let params = generics.params[..param_def_idx as usize].to_owned();
1539 let param_def_id_to_index =
1540 params.iter().map(|param| (param.def_id, param.index)).collect();
1542 return ty::Generics {
1543 // we set the parent of these generics to be our parent's parent so that we
1544 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1545 // struct Foo<const N: usize, const M: usize = { ... }>;
1546 parent: generics.parent,
1547 parent_count: generics.parent_count,
1549 param_def_id_to_index,
1550 has_self: generics.has_self,
1551 has_late_bound_regions: generics.has_late_bound_regions,
1555 // HACK(eddyb) this provides the correct generics when
1556 // `feature(generic_const_expressions)` is enabled, so that const expressions
1557 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1559 // Note that we do not supply the parent generics when using
1560 // `min_const_generics`.
1561 Some(parent_def_id.to_def_id())
1563 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1565 // HACK(eddyb) this provides the correct generics for repeat
1566 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1567 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1568 // as they shouldn't be able to cause query cycle errors.
1569 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1570 if constant.hir_id() == hir_id =>
1572 Some(parent_def_id.to_def_id())
1574 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1575 if constant.hir_id == hir_id =>
1577 Some(parent_def_id.to_def_id())
1579 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1580 Some(tcx.typeck_root_def_id(def_id))
1586 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1587 Some(tcx.typeck_root_def_id(def_id))
1589 Node::Item(item) => match item.kind {
1590 ItemKind::OpaqueTy(hir::OpaqueTy {
1592 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1594 }) => Some(fn_def_id.to_def_id()),
1595 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1596 let parent_id = tcx.hir().get_parent_item(hir_id);
1597 assert_ne!(parent_id, CRATE_DEF_ID);
1598 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1599 // Opaque types are always nested within another item, and
1600 // inherit the generics of the item.
1601 Some(parent_id.to_def_id())
1608 let mut opt_self = None;
1609 let mut allow_defaults = false;
1611 let no_generics = hir::Generics::empty();
1612 let ast_generics = match node {
1613 Node::TraitItem(item) => &item.generics,
1615 Node::ImplItem(item) => &item.generics,
1617 Node::Item(item) => {
1619 ItemKind::Fn(.., ref generics, _)
1620 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1622 ItemKind::TyAlias(_, ref generics)
1623 | ItemKind::Enum(_, ref generics)
1624 | ItemKind::Struct(_, ref generics)
1625 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1626 | ItemKind::Union(_, ref generics) => {
1627 allow_defaults = true;
1631 ItemKind::Trait(_, _, ref generics, ..)
1632 | ItemKind::TraitAlias(ref generics, ..) => {
1633 // Add in the self type parameter.
1635 // Something of a hack: use the node id for the trait, also as
1636 // the node id for the Self type parameter.
1637 let param_id = item.def_id;
1639 opt_self = Some(ty::GenericParamDef {
1641 name: kw::SelfUpper,
1642 def_id: param_id.to_def_id(),
1643 pure_wrt_drop: false,
1644 kind: ty::GenericParamDefKind::Type {
1646 object_lifetime_default: rl::Set1::Empty,
1651 allow_defaults = true;
1659 Node::ForeignItem(item) => match item.kind {
1660 ForeignItemKind::Static(..) => &no_generics,
1661 ForeignItemKind::Fn(_, _, ref generics) => generics,
1662 ForeignItemKind::Type => &no_generics,
1668 let has_self = opt_self.is_some();
1669 let mut parent_has_self = false;
1670 let mut own_start = has_self as u32;
1671 let parent_count = parent_def_id.map_or(0, |def_id| {
1672 let generics = tcx.generics_of(def_id);
1674 parent_has_self = generics.has_self;
1675 own_start = generics.count() as u32;
1676 generics.parent_count + generics.params.len()
1679 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1681 if let Some(opt_self) = opt_self {
1682 params.push(opt_self);
1685 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1686 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1687 name: param.name.ident().name,
1688 index: own_start + i as u32,
1689 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1690 pure_wrt_drop: param.pure_wrt_drop,
1691 kind: ty::GenericParamDefKind::Lifetime,
1694 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id.owner);
1696 // Now create the real type and const parameters.
1697 let type_start = own_start - has_self as u32 + params.len() as u32;
1700 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1701 GenericParamKind::Lifetime { .. } => None,
1702 GenericParamKind::Type { ref default, synthetic, .. } => {
1703 if !allow_defaults && default.is_some() {
1704 if !tcx.features().default_type_parameter_fallback {
1705 tcx.struct_span_lint_hir(
1706 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1711 "defaults for type parameters are only allowed in \
1712 `struct`, `enum`, `type`, or `trait` definitions",
1720 let kind = ty::GenericParamDefKind::Type {
1721 has_default: default.is_some(),
1722 object_lifetime_default: object_lifetime_defaults
1724 .map_or(rl::Set1::Empty, |o| o[i]),
1728 let param_def = ty::GenericParamDef {
1729 index: type_start + i as u32,
1730 name: param.name.ident().name,
1731 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1732 pure_wrt_drop: param.pure_wrt_drop,
1738 GenericParamKind::Const { default, .. } => {
1739 if !allow_defaults && default.is_some() {
1742 "defaults for const parameters are only allowed in \
1743 `struct`, `enum`, `type`, or `trait` definitions",
1747 let param_def = ty::GenericParamDef {
1748 index: type_start + i as u32,
1749 name: param.name.ident().name,
1750 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1751 pure_wrt_drop: param.pure_wrt_drop,
1752 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1759 // provide junk type parameter defs - the only place that
1760 // cares about anything but the length is instantiation,
1761 // and we don't do that for closures.
1762 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1763 let dummy_args = if gen.is_some() {
1764 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1766 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1769 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1770 index: type_start + i as u32,
1771 name: Symbol::intern(arg),
1773 pure_wrt_drop: false,
1774 kind: ty::GenericParamDefKind::Type {
1776 object_lifetime_default: rl::Set1::Empty,
1782 // provide junk type parameter defs for const blocks.
1783 if let Node::AnonConst(_) = node {
1784 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1785 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1786 params.push(ty::GenericParamDef {
1788 name: Symbol::intern("<const_ty>"),
1790 pure_wrt_drop: false,
1791 kind: ty::GenericParamDefKind::Type {
1793 object_lifetime_default: rl::Set1::Empty,
1800 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1803 parent: parent_def_id,
1806 param_def_id_to_index,
1807 has_self: has_self || parent_has_self,
1808 has_late_bound_regions: has_late_bound_regions(tcx, node),
1812 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1813 generic_args.iter().any(|arg| match arg {
1814 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1815 hir::GenericArg::Infer(_) => true,
1820 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1821 /// use inference to provide suggestions for the appropriate type if possible.
1822 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1827 Slice(ty) => is_suggestable_infer_ty(ty),
1828 Array(ty, length) => {
1829 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1831 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1832 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1833 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1834 Path(hir::QPath::TypeRelative(ty, segment)) => {
1835 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1837 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1838 ty_opt.map_or(false, is_suggestable_infer_ty)
1839 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1845 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1846 if let hir::FnRetTy::Return(ty) = output {
1847 if is_suggestable_infer_ty(ty) {
1854 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1855 use rustc_hir::Node::*;
1858 let def_id = def_id.expect_local();
1859 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1861 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1863 match tcx.hir().get(hir_id) {
1864 TraitItem(hir::TraitItem {
1865 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1870 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1871 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1872 match get_infer_ret_ty(&sig.decl.output) {
1874 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1875 // Typeck doesn't expect erased regions to be returned from `type_of`.
1876 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match *r {
1877 ty::ReErased => tcx.lifetimes.re_static,
1880 let fn_sig = ty::Binder::dummy(fn_sig);
1882 let mut visitor = HirPlaceholderCollector::default();
1883 visitor.visit_ty(ty);
1884 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1885 let ret_ty = fn_sig.skip_binder().output();
1886 if !ret_ty.references_error() {
1887 if !ret_ty.is_closure() {
1888 let ret_ty_str = match ret_ty.kind() {
1889 // Suggest a function pointer return type instead of a unique function definition
1890 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1892 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1893 _ => ret_ty.to_string(),
1895 diag.span_suggestion(
1897 "replace with the correct return type",
1899 Applicability::MaybeIncorrect,
1902 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1903 // to prevent the user from getting a papercut while trying to use the unique closure
1904 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1905 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1906 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1913 None => <dyn AstConv<'_>>::ty_of_fn(
1916 sig.header.unsafety,
1926 TraitItem(hir::TraitItem {
1927 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1931 }) => <dyn AstConv<'_>>::ty_of_fn(
1942 ForeignItem(&hir::ForeignItem {
1943 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1945 let abi = tcx.hir().get_foreign_abi(hir_id);
1946 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1949 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1950 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1952 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1953 ty::Binder::dummy(tcx.mk_fn_sig(
1957 hir::Unsafety::Normal,
1962 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1963 // Closure signatures are not like other function
1964 // signatures and cannot be accessed through `fn_sig`. For
1965 // example, a closure signature excludes the `self`
1966 // argument. In any case they are embedded within the
1967 // closure type as part of the `ClosureSubsts`.
1969 // To get the signature of a closure, you should use the
1970 // `sig` method on the `ClosureSubsts`:
1972 // substs.as_closure().sig(def_id, tcx)
1974 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1979 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1984 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1985 let icx = ItemCtxt::new(tcx, def_id);
1986 match tcx.hir().expect_item(def_id.expect_local()).kind {
1987 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1988 let selfty = tcx.type_of(def_id);
1989 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1995 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1996 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1997 let item = tcx.hir().expect_item(def_id.expect_local());
1999 hir::ItemKind::Impl(hir::Impl {
2000 polarity: hir::ImplPolarity::Negative(span),
2004 if is_rustc_reservation {
2005 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
2006 tcx.sess.span_err(span, "reservation impls can't be negative");
2008 ty::ImplPolarity::Negative
2010 hir::ItemKind::Impl(hir::Impl {
2011 polarity: hir::ImplPolarity::Positive,
2015 if is_rustc_reservation {
2016 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2018 ty::ImplPolarity::Positive
2020 hir::ItemKind::Impl(hir::Impl {
2021 polarity: hir::ImplPolarity::Positive,
2025 if is_rustc_reservation {
2026 ty::ImplPolarity::Reservation
2028 ty::ImplPolarity::Positive
2031 item => bug!("impl_polarity: {:?} not an impl", item),
2035 /// Returns the early-bound lifetimes declared in this generics
2036 /// listing. For anything other than fns/methods, this is just all
2037 /// the lifetimes that are declared. For fns or methods, we have to
2038 /// screen out those that do not appear in any where-clauses etc using
2039 /// `resolve_lifetime::early_bound_lifetimes`.
2040 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2042 generics: &'a hir::Generics<'a>,
2043 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2044 generics.params.iter().filter(move |param| match param.kind {
2045 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
2050 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2051 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2052 /// inferred constraints concerning which regions outlive other regions.
2053 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2054 debug!("predicates_defined_on({:?})", def_id);
2055 let mut result = tcx.explicit_predicates_of(def_id);
2056 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2057 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2058 if !inferred_outlives.is_empty() {
2060 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2061 def_id, inferred_outlives,
2063 if result.predicates.is_empty() {
2064 result.predicates = inferred_outlives;
2066 result.predicates = tcx
2068 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2072 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2076 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2077 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2078 /// `Self: Trait` predicates for traits.
2079 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2080 let mut result = tcx.predicates_defined_on(def_id);
2082 if tcx.is_trait(def_id) {
2083 // For traits, add `Self: Trait` predicate. This is
2084 // not part of the predicates that a user writes, but it
2085 // is something that one must prove in order to invoke a
2086 // method or project an associated type.
2088 // In the chalk setup, this predicate is not part of the
2089 // "predicates" for a trait item. But it is useful in
2090 // rustc because if you directly (e.g.) invoke a trait
2091 // method like `Trait::method(...)`, you must naturally
2092 // prove that the trait applies to the types that were
2093 // used, and adding the predicate into this list ensures
2094 // that this is done.
2096 // We use a DUMMY_SP here as a way to signal trait bounds that come
2097 // from the trait itself that *shouldn't* be shown as the source of
2098 // an obligation and instead be skipped. Otherwise we'd use
2099 // `tcx.def_span(def_id);`
2100 let span = rustc_span::DUMMY_SP;
2102 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2103 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2107 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2111 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2112 /// N.B., this does not include any implied/inferred constraints.
2113 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2116 debug!("explicit_predicates_of(def_id={:?})", def_id);
2118 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2119 let node = tcx.hir().get(hir_id);
2121 let mut is_trait = None;
2122 let mut is_default_impl_trait = None;
2124 let icx = ItemCtxt::new(tcx, def_id);
2126 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2128 // We use an `IndexSet` to preserves order of insertion.
2129 // Preserving the order of insertion is important here so as not to break UI tests.
2130 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2132 let ast_generics = match node {
2133 Node::TraitItem(item) => &item.generics,
2135 Node::ImplItem(item) => &item.generics,
2137 Node::Item(item) => {
2139 ItemKind::Impl(ref impl_) => {
2140 if impl_.defaultness.is_default() {
2141 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2145 ItemKind::Fn(.., ref generics, _)
2146 | ItemKind::TyAlias(_, ref generics)
2147 | ItemKind::Enum(_, ref generics)
2148 | ItemKind::Struct(_, ref generics)
2149 | ItemKind::Union(_, ref generics) => generics,
2151 ItemKind::Trait(_, _, ref generics, ..) => {
2152 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2155 ItemKind::TraitAlias(ref generics, _) => {
2156 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2159 ItemKind::OpaqueTy(OpaqueTy {
2160 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2163 // return-position impl trait
2165 // We don't inherit predicates from the parent here:
2166 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2167 // then the return type is `f::<'static, T>::{{opaque}}`.
2169 // If we inherited the predicates of `f` then we would
2170 // require that `T: 'static` to show that the return
2171 // type is well-formed.
2173 // The only way to have something with this opaque type
2174 // is from the return type of the containing function,
2175 // which will ensure that the function's predicates
2177 return ty::GenericPredicates { parent: None, predicates: &[] };
2179 ItemKind::OpaqueTy(OpaqueTy {
2181 origin: hir::OpaqueTyOrigin::TyAlias,
2184 // type-alias impl trait
2192 Node::ForeignItem(item) => match item.kind {
2193 ForeignItemKind::Static(..) => NO_GENERICS,
2194 ForeignItemKind::Fn(_, _, ref generics) => generics,
2195 ForeignItemKind::Type => NO_GENERICS,
2201 let generics = tcx.generics_of(def_id);
2202 let parent_count = generics.parent_count as u32;
2203 let has_own_self = generics.has_self && parent_count == 0;
2205 // Below we'll consider the bounds on the type parameters (including `Self`)
2206 // and the explicit where-clauses, but to get the full set of predicates
2207 // on a trait we need to add in the supertrait bounds and bounds found on
2208 // associated types.
2209 if let Some(_trait_ref) = is_trait {
2210 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2213 // In default impls, we can assume that the self type implements
2214 // the trait. So in:
2216 // default impl Foo for Bar { .. }
2218 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2219 // (see below). Recall that a default impl is not itself an impl, but rather a
2220 // set of defaults that can be incorporated into another impl.
2221 if let Some(trait_ref) = is_default_impl_trait {
2222 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2225 // Collect the region predicates that were declared inline as
2226 // well. In the case of parameters declared on a fn or method, we
2227 // have to be careful to only iterate over early-bound regions.
2228 let mut index = parent_count + has_own_self as u32;
2229 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2230 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2231 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2233 name: param.name.ident().name,
2238 GenericParamKind::Lifetime { .. } => {
2239 param.bounds.iter().for_each(|bound| match bound {
2240 hir::GenericBound::Outlives(lt) => {
2241 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2242 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2243 predicates.insert((outlives.to_predicate(tcx), lt.span));
2252 // Collect the predicates that were written inline by the user on each
2253 // type parameter (e.g., `<T: Foo>`).
2254 for param in ast_generics.params {
2256 // We already dealt with early bound lifetimes above.
2257 GenericParamKind::Lifetime { .. } => (),
2258 GenericParamKind::Type { .. } => {
2259 let name = param.name.ident().name;
2260 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2263 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2264 // Params are implicitly sized unless a `?Sized` bound is found
2265 <dyn AstConv<'_>>::add_implicitly_sized(
2269 Some((param.hir_id, ast_generics.where_clause.predicates)),
2272 predicates.extend(bounds.predicates(tcx, param_ty));
2274 GenericParamKind::Const { .. } => {
2275 // Bounds on const parameters are currently not possible.
2276 debug_assert!(param.bounds.is_empty());
2282 // Add in the bounds that appear in the where-clause.
2283 let where_clause = &ast_generics.where_clause;
2284 for predicate in where_clause.predicates {
2286 hir::WherePredicate::BoundPredicate(bound_pred) => {
2287 let ty = icx.to_ty(bound_pred.bounded_ty);
2288 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2290 // Keep the type around in a dummy predicate, in case of no bounds.
2291 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2292 // is still checked for WF.
2293 if bound_pred.bounds.is_empty() {
2294 if let ty::Param(_) = ty.kind() {
2295 // This is a `where T:`, which can be in the HIR from the
2296 // transformation that moves `?Sized` to `T`'s declaration.
2297 // We can skip the predicate because type parameters are
2298 // trivially WF, but also we *should*, to avoid exposing
2299 // users who never wrote `where Type:,` themselves, to
2300 // compiler/tooling bugs from not handling WF predicates.
2302 let span = bound_pred.bounded_ty.span;
2303 let re_root_empty = tcx.lifetimes.re_root_empty;
2304 let predicate = ty::Binder::bind_with_vars(
2305 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2311 predicates.insert((predicate.to_predicate(tcx), span));
2315 let mut bounds = Bounds::default();
2316 <dyn AstConv<'_>>::add_bounds(
2319 bound_pred.bounds.iter(),
2323 predicates.extend(bounds.predicates(tcx, ty));
2326 hir::WherePredicate::RegionPredicate(region_pred) => {
2327 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2328 predicates.extend(region_pred.bounds.iter().map(|bound| {
2329 let (r2, span) = match bound {
2330 hir::GenericBound::Outlives(lt) => {
2331 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2335 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2336 ty::OutlivesPredicate(r1, r2),
2338 .to_predicate(icx.tcx);
2344 hir::WherePredicate::EqPredicate(..) => {
2350 if tcx.features().generic_const_exprs {
2351 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2354 let mut predicates: Vec<_> = predicates.into_iter().collect();
2356 // Subtle: before we store the predicates into the tcx, we
2357 // sort them so that predicates like `T: Foo<Item=U>` come
2358 // before uses of `U`. This avoids false ambiguity errors
2359 // in trait checking. See `setup_constraining_predicates`
2361 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2362 let self_ty = tcx.type_of(def_id);
2363 let trait_ref = tcx.impl_trait_ref(def_id);
2364 cgp::setup_constraining_predicates(
2368 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2372 let result = ty::GenericPredicates {
2373 parent: generics.parent,
2374 predicates: tcx.arena.alloc_from_iter(predicates),
2376 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2380 fn const_evaluatable_predicates_of<'tcx>(
2383 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2384 struct ConstCollector<'tcx> {
2386 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2389 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2390 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2391 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2392 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2393 if let ty::ConstKind::Unevaluated(uv) = ct.val() {
2394 assert_eq!(uv.promoted, None);
2395 let span = self.tcx.hir().span(c.hir_id);
2397 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2398 .to_predicate(self.tcx),
2404 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2405 // Do not look into const param defaults,
2406 // these get checked when they are actually instantiated.
2408 // We do not want the following to error:
2410 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2411 // struct Bar<const N: usize>(Foo<N, 3>);
2415 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2416 let node = tcx.hir().get(hir_id);
2418 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2419 if let hir::Node::Item(item) = node {
2420 if let hir::ItemKind::Impl(ref impl_) = item.kind {
2421 if let Some(of_trait) = &impl_.of_trait {
2422 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2423 collector.visit_trait_ref(of_trait);
2426 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2427 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: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
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<'_>| {
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() == 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>,
2545 ) -> ty::PolyFnSig<'tcx> {
2546 let unsafety = if abi == abi::Abi::RustIntrinsic {
2547 intrinsic_operation_unsafety(tcx.item_name(def_id))
2549 hir::Unsafety::Unsafe
2551 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2552 let fty = <dyn AstConv<'_>>::ty_of_fn(
2553 &ItemCtxt::new(tcx, def_id),
2558 &hir::Generics::empty(),
2563 // Feature gate SIMD types in FFI, since I am not sure that the
2564 // ABIs are handled at all correctly. -huonw
2565 if abi != abi::Abi::RustIntrinsic
2566 && abi != abi::Abi::PlatformIntrinsic
2567 && !tcx.features().simd_ffi
2569 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2574 .span_to_snippet(ast_ty.span)
2575 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2580 "use of SIMD type{} in FFI is highly experimental and \
2581 may result in invalid code",
2585 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2589 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2592 if let hir::FnRetTy::Return(ref ty) = decl.output {
2593 check(ty, fty.output().skip_binder())
2600 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2601 match tcx.hir().get_if_local(def_id) {
2602 Some(Node::ForeignItem(..)) => true,
2604 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2608 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2609 match tcx.hir().get_if_local(def_id) {
2611 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2612 | Node::ForeignItem(&hir::ForeignItem {
2613 kind: hir::ForeignItemKind::Static(_, mutbl),
2618 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2622 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2623 match tcx.hir().get_if_local(def_id) {
2624 Some(Node::Expr(&rustc_hir::Expr {
2625 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2627 })) => tcx.hir().body(body_id).generator_kind(),
2629 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2633 fn from_target_feature(
2636 attr: &ast::Attribute,
2637 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2638 target_features: &mut Vec<Symbol>,
2640 let list = match attr.meta_item_list() {
2644 let bad_item = |span| {
2645 let msg = "malformed `target_feature` attribute input";
2646 let code = "enable = \"..\"".to_owned();
2648 .struct_span_err(span, msg)
2649 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2652 let rust_features = tcx.features();
2654 // Only `enable = ...` is accepted in the meta-item list.
2655 if !item.has_name(sym::enable) {
2656 bad_item(item.span());
2660 // Must be of the form `enable = "..."` (a string).
2661 let value = match item.value_str() {
2662 Some(value) => value,
2664 bad_item(item.span());
2669 // We allow comma separation to enable multiple features.
2670 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2671 let feature_gate = match supported_target_features.get(feature) {
2675 format!("the feature named `{}` is not valid for this target", feature);
2676 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2679 format!("`{}` is not valid for this target", feature),
2681 if let Some(stripped) = feature.strip_prefix('+') {
2682 let valid = supported_target_features.contains_key(stripped);
2684 err.help("consider removing the leading `+` in the feature name");
2692 // Only allow features whose feature gates have been enabled.
2693 let allowed = match feature_gate.as_ref().copied() {
2694 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2695 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2696 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2697 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2698 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2699 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2700 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2701 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2702 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2703 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2704 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2705 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2706 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2707 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2708 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2709 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2710 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2711 Some(name) => bug!("unknown target feature gate {}", name),
2714 if !allowed && id.is_local() {
2716 &tcx.sess.parse_sess,
2717 feature_gate.unwrap(),
2719 &format!("the target feature `{}` is currently unstable", feature),
2723 Some(Symbol::intern(feature))
2728 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2729 use rustc_middle::mir::mono::Linkage::*;
2731 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2732 // applicable to variable declarations and may not really make sense for
2733 // Rust code in the first place but allow them anyway and trust that the
2734 // user knows what s/he's doing. Who knows, unanticipated use cases may pop
2735 // up in the future.
2737 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2738 // and don't have to be, LLVM treats them as no-ops.
2740 "appending" => Appending,
2741 "available_externally" => AvailableExternally,
2743 "extern_weak" => ExternalWeak,
2744 "external" => External,
2745 "internal" => Internal,
2746 "linkonce" => LinkOnceAny,
2747 "linkonce_odr" => LinkOnceODR,
2748 "private" => Private,
2750 "weak_odr" => WeakODR,
2752 let span = tcx.hir().span_if_local(def_id);
2753 if let Some(span) = span {
2754 tcx.sess.span_fatal(span, "invalid linkage specified")
2756 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2762 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2763 let attrs = tcx.get_attrs(id);
2765 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2766 if tcx.should_inherit_track_caller(id) {
2767 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2770 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2771 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2772 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2773 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2777 // The panic_no_unwind function called by TerminatorKind::Abort will never
2778 // unwind. If the panic handler that it invokes unwind then it will simply
2779 // call the panic handler again.
2780 if Some(id) == tcx.lang_items().panic_no_unwind() {
2781 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2784 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2786 let mut inline_span = None;
2787 let mut link_ordinal_span = None;
2788 let mut no_sanitize_span = None;
2789 for attr in attrs.iter() {
2790 if attr.has_name(sym::cold) {
2791 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2792 } else if attr.has_name(sym::rustc_allocator) {
2793 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2794 } else if attr.has_name(sym::ffi_returns_twice) {
2795 if tcx.is_foreign_item(id) {
2796 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2798 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2803 "`#[ffi_returns_twice]` may only be used on foreign functions"
2807 } else if attr.has_name(sym::ffi_pure) {
2808 if tcx.is_foreign_item(id) {
2809 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2810 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2815 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2819 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2822 // `#[ffi_pure]` is only allowed on foreign functions
2827 "`#[ffi_pure]` may only be used on foreign functions"
2831 } else if attr.has_name(sym::ffi_const) {
2832 if tcx.is_foreign_item(id) {
2833 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2835 // `#[ffi_const]` is only allowed on foreign functions
2840 "`#[ffi_const]` may only be used on foreign functions"
2844 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2845 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2846 } else if attr.has_name(sym::naked) {
2847 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2848 } else if attr.has_name(sym::no_mangle) {
2849 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2850 } else if attr.has_name(sym::no_coverage) {
2851 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2852 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2853 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2854 } else if attr.has_name(sym::used) {
2855 let inner = attr.meta_item_list();
2856 match inner.as_deref() {
2857 Some([item]) if item.has_name(sym::linker) => {
2858 if !tcx.features().used_with_arg {
2860 &tcx.sess.parse_sess,
2863 "`#[used(linker)]` is currently unstable",
2867 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2869 Some([item]) if item.has_name(sym::compiler) => {
2870 if !tcx.features().used_with_arg {
2872 &tcx.sess.parse_sess,
2875 "`#[used(compiler)]` is currently unstable",
2879 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2885 "expected `used`, `used(compiler)` or `used(linker)`",
2889 None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
2891 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2892 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2897 "`#[cmse_nonsecure_entry]` requires C ABI"
2901 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2902 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2905 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2906 } else if attr.has_name(sym::thread_local) {
2907 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2908 } else if attr.has_name(sym::track_caller) {
2909 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2910 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2913 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2915 &tcx.sess.parse_sess,
2916 sym::closure_track_caller,
2918 "`#[track_caller]` on closures is currently unstable",
2922 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2923 } else if attr.has_name(sym::export_name) {
2924 if let Some(s) = attr.value_str() {
2925 if s.as_str().contains('\0') {
2926 // `#[export_name = ...]` will be converted to a null-terminated string,
2927 // so it may not contain any null characters.
2932 "`export_name` may not contain null characters"
2936 codegen_fn_attrs.export_name = Some(s);
2938 } else if attr.has_name(sym::target_feature) {
2939 if !tcx.is_closure(id) && tcx.fn_sig(id).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 funtions (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(id), "not an `unsafe` function");
2967 } else if let Some(local_id) = id.as_local() {
2968 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2971 from_target_feature(
2975 supported_target_features,
2976 &mut codegen_fn_attrs.target_features,
2978 } else if attr.has_name(sym::linkage) {
2979 if let Some(val) = attr.value_str() {
2980 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, val.as_str()));
2982 } else if attr.has_name(sym::link_section) {
2983 if let Some(val) = attr.value_str() {
2984 if val.as_str().bytes().any(|b| b == 0) {
2986 "illegal null byte in link_section \
2990 tcx.sess.span_err(attr.span, &msg);
2992 codegen_fn_attrs.link_section = Some(val);
2995 } else if attr.has_name(sym::link_name) {
2996 codegen_fn_attrs.link_name = attr.value_str();
2997 } else if attr.has_name(sym::link_ordinal) {
2998 link_ordinal_span = Some(attr.span);
2999 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
3000 codegen_fn_attrs.link_ordinal = ordinal;
3002 } else if attr.has_name(sym::no_sanitize) {
3003 no_sanitize_span = Some(attr.span);
3004 if let Some(list) = attr.meta_item_list() {
3005 for item in list.iter() {
3006 if item.has_name(sym::address) {
3007 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
3008 } else if item.has_name(sym::cfi) {
3009 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
3010 } else if item.has_name(sym::memory) {
3011 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
3012 } else if item.has_name(sym::thread) {
3013 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
3014 } else if item.has_name(sym::hwaddress) {
3015 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
3018 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
3019 .note("expected one of: `address`, `hwaddress`, `memory` or `thread`")
3024 } else if attr.has_name(sym::instruction_set) {
3025 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
3026 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
3027 [NestedMetaItem::MetaItem(set)] => {
3029 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
3030 match segments.as_slice() {
3031 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3032 if !tcx.sess.target.has_thumb_interworking {
3034 tcx.sess.diagnostic(),
3037 "target does not support `#[instruction_set]`"
3041 } else if segments[1] == sym::a32 {
3042 Some(InstructionSetAttr::ArmA32)
3043 } else if segments[1] == sym::t32 {
3044 Some(InstructionSetAttr::ArmT32)
3051 tcx.sess.diagnostic(),
3054 "invalid instruction set specified",
3063 tcx.sess.diagnostic(),
3066 "`#[instruction_set]` requires an argument"
3073 tcx.sess.diagnostic(),
3076 "cannot specify more than one instruction set"
3084 tcx.sess.diagnostic(),
3087 "must specify an instruction set"
3093 } else if attr.has_name(sym::repr) {
3094 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3095 Some(items) => match items.as_slice() {
3096 [item] => match item.name_value_literal() {
3097 Some((sym::align, literal)) => {
3098 let alignment = rustc_attr::parse_alignment(&literal.kind);
3101 Ok(align) => Some(align),
3104 tcx.sess.diagnostic(),
3107 "invalid `repr(align)` attribute: {}",
3126 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3127 if !attr.has_name(sym::inline) {
3130 match attr.meta_kind() {
3131 Some(MetaItemKind::Word) => InlineAttr::Hint,
3132 Some(MetaItemKind::List(ref items)) => {
3133 inline_span = Some(attr.span);
3134 if items.len() != 1 {
3136 tcx.sess.diagnostic(),
3139 "expected one argument"
3143 } else if list_contains_name(&items, sym::always) {
3145 } else if list_contains_name(&items, sym::never) {
3149 tcx.sess.diagnostic(),
3159 Some(MetaItemKind::NameValue(_)) => ia,
3164 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3165 if !attr.has_name(sym::optimize) {
3168 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3169 match attr.meta_kind() {
3170 Some(MetaItemKind::Word) => {
3171 err(attr.span, "expected one argument");
3174 Some(MetaItemKind::List(ref items)) => {
3175 inline_span = Some(attr.span);
3176 if items.len() != 1 {
3177 err(attr.span, "expected one argument");
3179 } else if list_contains_name(&items, sym::size) {
3181 } else if list_contains_name(&items, sym::speed) {
3184 err(items[0].span(), "invalid argument");
3188 Some(MetaItemKind::NameValue(_)) => ia,
3193 // #73631: closures inherit `#[target_feature]` annotations
3194 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3195 let owner_id = tcx.parent(id).expect("closure should have a parent");
3198 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3201 // If a function uses #[target_feature] it can't be inlined into general
3202 // purpose functions as they wouldn't have the right target features
3203 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3205 if !codegen_fn_attrs.target_features.is_empty() {
3206 if codegen_fn_attrs.inline == InlineAttr::Always {
3207 if let Some(span) = inline_span {
3210 "cannot use `#[inline(always)]` with \
3211 `#[target_feature]`",
3217 if !codegen_fn_attrs.no_sanitize.is_empty() {
3218 if codegen_fn_attrs.inline == InlineAttr::Always {
3219 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3220 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3221 tcx.struct_span_lint_hir(
3222 lint::builtin::INLINE_NO_SANITIZE,
3226 lint.build("`no_sanitize` will have no effect after inlining")
3227 .span_note(inline_span, "inlining requested here")
3235 // Weak lang items have the same semantics as "std internal" symbols in the
3236 // sense that they're preserved through all our LTO passes and only
3237 // strippable by the linker.
3239 // Additionally weak lang items have predetermined symbol names.
3240 if tcx.is_weak_lang_item(id) {
3241 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3243 if let Some(name) = weak_lang_items::link_name(attrs) {
3244 codegen_fn_attrs.export_name = Some(name);
3245 codegen_fn_attrs.link_name = Some(name);
3247 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3249 // Internal symbols to the standard library all have no_mangle semantics in
3250 // that they have defined symbol names present in the function name. This
3251 // also applies to weak symbols where they all have known symbol names.
3252 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3253 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3256 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3257 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3258 // intrinsic functions.
3259 if let Some(name) = &codegen_fn_attrs.link_name {
3260 if name.as_str().starts_with("llvm.") {
3261 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3268 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3269 /// applied to the method prototype.
3270 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3271 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
3272 if let ty::AssocItemContainer::ImplContainer(_) = impl_item.container {
3273 if let Some(trait_item) = impl_item.trait_item_def_id {
3275 .codegen_fn_attrs(trait_item)
3277 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3285 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3286 use rustc_ast::{Lit, LitIntType, LitKind};
3287 let meta_item_list = attr.meta_item_list();
3288 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3289 let sole_meta_list = match meta_item_list {
3290 Some([item]) => item.literal(),
3293 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3294 .note("the attribute requires exactly one argument")
3300 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3301 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3302 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3303 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3304 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3306 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3307 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3308 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3309 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3310 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3311 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3312 // about LINK.EXE failing.)
3313 if *ordinal <= u16::MAX as u128 {
3314 Some(*ordinal as u16)
3316 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3318 .struct_span_err(attr.span, &msg)
3319 .note("the value may not exceed `u16::MAX`")
3325 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3326 .note("an unsuffixed integer value, e.g., `1`, is expected")
3332 fn check_link_name_xor_ordinal(
3334 codegen_fn_attrs: &CodegenFnAttrs,
3335 inline_span: Option<Span>,
3337 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3340 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3341 if let Some(span) = inline_span {
3342 tcx.sess.span_err(span, msg);
3348 /// Checks the function annotated with `#[target_feature]` is not a safe
3349 /// trait method implementation, reporting an error if it is.
3350 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3351 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3352 let node = tcx.hir().get(hir_id);
3353 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3354 let parent_id = tcx.hir().get_parent_item(hir_id);
3355 let parent_item = tcx.hir().expect_item(parent_id);
3356 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3360 "`#[target_feature(..)]` cannot be applied to safe trait method",
3362 .span_label(attr_span, "cannot be applied to safe trait method")
3363 .span_label(tcx.def_span(id), "not an `unsafe` function")