1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::AstConv;
18 use crate::bounds::Bounds;
19 use crate::check::intrinsic::intrinsic_operation_unsafety;
20 use crate::constrained_generic_params as cgp;
22 use crate::middle::resolve_lifetime as rl;
24 use rustc_ast::Attribute;
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, LOCAL_CRATE};
33 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
34 use rustc_hir::weak_lang_items;
35 use rustc_hir::{GenericParamKind, HirId, Node};
36 use rustc_middle::hir::map::Map;
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, WithConstness};
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 default_anon_const_substs: type_of::default_anon_const_substs,
72 type_of: type_of::type_of,
73 item_bounds: item_bounds::item_bounds,
74 explicit_item_bounds: item_bounds::explicit_item_bounds,
77 predicates_defined_on,
78 explicit_predicates_of,
80 super_predicates_that_define_assoc_type,
81 trait_explicit_predicates_and_bounds,
82 type_param_predicates,
92 collect_mod_item_types,
93 should_inherit_track_caller,
98 ///////////////////////////////////////////////////////////////////////////
100 /// Context specific to some particular item. This is what implements
101 /// `AstConv`. It has information about the predicates that are defined
102 /// on the trait. Unfortunately, this predicate information is
103 /// available in various different forms at various points in the
104 /// process. So we can't just store a pointer to e.g., the AST or the
105 /// parsed ty form, we have to be more flexible. To this end, the
106 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
107 /// `get_type_parameter_bounds` requests, drawing the information from
108 /// the AST (`hir::Generics`), recursively.
109 pub struct ItemCtxt<'tcx> {
114 ///////////////////////////////////////////////////////////////////////////
117 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
119 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
120 type Map = intravisit::ErasedMap<'v>;
122 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
123 NestedVisitorMap::None
125 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
126 if let hir::TyKind::Infer = t.kind {
129 intravisit::walk_ty(self, t)
131 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
133 hir::GenericArg::Infer(inf) => {
134 self.0.push(inf.span);
135 intravisit::walk_inf(self, inf);
137 hir::GenericArg::Type(t) => self.visit_ty(t),
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(
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_type(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: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
227 let (generics, suggest) = match &item.kind {
228 hir::ItemKind::Union(_, generics)
229 | hir::ItemKind::Enum(_, generics)
230 | hir::ItemKind::TraitAlias(generics, _)
231 | hir::ItemKind::Trait(_, _, generics, ..)
232 | hir::ItemKind::Impl(hir::Impl { generics, .. })
233 | hir::ItemKind::Struct(_, generics) => (generics, true),
234 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
235 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
236 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
240 let mut visitor = PlaceholderHirTyCollector::default();
241 visitor.visit_item(item);
243 placeholder_type_error(
254 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
255 type Map = Map<'tcx>;
257 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
258 NestedVisitorMap::OnlyBodies(self.tcx.hir())
261 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
262 convert_item(self.tcx, item.item_id());
263 reject_placeholder_type_signatures_in_item(self.tcx, item);
264 intravisit::walk_item(self, item);
267 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
268 for param in generics.params {
270 hir::GenericParamKind::Lifetime { .. } => {}
271 hir::GenericParamKind::Type { default: Some(_), .. } => {
272 let def_id = self.tcx.hir().local_def_id(param.hir_id);
273 self.tcx.ensure().type_of(def_id);
275 hir::GenericParamKind::Type { .. } => {}
276 hir::GenericParamKind::Const { default, .. } => {
277 let def_id = self.tcx.hir().local_def_id(param.hir_id);
278 self.tcx.ensure().type_of(def_id);
279 if let Some(default) = default {
280 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
281 // need to store default and type of default
282 self.tcx.ensure().type_of(default_def_id);
283 self.tcx.ensure().const_param_default(def_id);
288 intravisit::walk_generics(self, generics);
291 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
292 if let hir::ExprKind::Closure(..) = expr.kind {
293 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
294 self.tcx.ensure().generics_of(def_id);
295 self.tcx.ensure().type_of(def_id);
297 intravisit::walk_expr(self, expr);
300 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
301 convert_trait_item(self.tcx, trait_item.trait_item_id());
302 intravisit::walk_trait_item(self, trait_item);
305 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
306 convert_impl_item(self.tcx, impl_item.impl_item_id());
307 intravisit::walk_impl_item(self, impl_item);
311 ///////////////////////////////////////////////////////////////////////////
312 // Utility types and common code for the above passes.
314 fn bad_placeholder_type(
316 mut spans: Vec<Span>,
318 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
319 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
322 let mut err = struct_span_err!(
326 "the type placeholder `_` is not allowed within types on item signatures for {}",
330 err.span_label(span, "not allowed in type signatures");
335 impl ItemCtxt<'tcx> {
336 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
337 ItemCtxt { tcx, item_def_id }
340 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
341 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
344 pub fn hir_id(&self) -> hir::HirId {
345 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
348 pub fn node(&self) -> hir::Node<'tcx> {
349 self.tcx.hir().get(self.hir_id())
353 impl AstConv<'tcx> for ItemCtxt<'tcx> {
354 fn tcx(&self) -> TyCtxt<'tcx> {
358 fn item_def_id(&self) -> Option<DefId> {
359 Some(self.item_def_id)
362 fn get_type_parameter_bounds(
367 ) -> ty::GenericPredicates<'tcx> {
368 self.tcx.at(span).type_param_predicates((
370 def_id.expect_local(),
375 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
379 fn allow_ty_infer(&self) -> bool {
383 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
384 self.tcx().ty_error_with_message(span, "bad_placeholder_type")
390 _: Option<&ty::GenericParamDef>,
392 ) -> &'tcx Const<'tcx> {
393 bad_placeholder_type(self.tcx(), vec![span], "generic").emit();
394 // Typeck doesn't expect erased regions to be returned from `type_of`.
395 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match r {
396 ty::ReErased => self.tcx.lifetimes.re_static,
399 self.tcx().const_error(ty)
402 fn projected_ty_from_poly_trait_ref(
406 item_segment: &hir::PathSegment<'_>,
407 poly_trait_ref: ty::PolyTraitRef<'tcx>,
409 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
410 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
418 self.tcx().mk_projection(item_def_id, item_substs)
420 // There are no late-bound regions; we can just ignore the binder.
421 let mut err = struct_span_err!(
425 "cannot use the associated type of a trait \
426 with uninferred generic parameters"
430 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
432 self.tcx.hir().expect_item(self.tcx.hir().get_parent_did(self.hir_id()));
434 hir::ItemKind::Enum(_, generics)
435 | hir::ItemKind::Struct(_, generics)
436 | hir::ItemKind::Union(_, generics) => {
437 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
438 let (lt_sp, sugg) = match generics.params {
439 [] => (generics.span, format!("<{}>", lt_name)),
441 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
444 let suggestions = vec![
447 span.with_hi(item_segment.ident.span.lo()),
450 // Replace the existing lifetimes with a new named lifetime.
452 .replace_late_bound_regions(poly_trait_ref, |_| {
453 self.tcx.mk_region(ty::ReEarlyBound(
454 ty::EarlyBoundRegion {
457 name: Symbol::intern(<_name),
465 err.multipart_suggestion(
466 "use a fully qualified path with explicit lifetimes",
468 Applicability::MaybeIncorrect,
474 hir::Node::Item(hir::Item {
476 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
480 | hir::Node::ForeignItem(_)
481 | hir::Node::TraitItem(_)
482 | hir::Node::ImplItem(_) => {
483 err.span_suggestion_verbose(
484 span.with_hi(item_segment.ident.span.lo()),
485 "use a fully qualified path with inferred lifetimes",
488 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
489 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
491 Applicability::MaybeIncorrect,
497 self.tcx().ty_error()
501 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
502 // Types in item signatures are not normalized to avoid undue dependencies.
506 fn set_tainted_by_errors(&self) {
507 // There's no obvious place to track this, so just let it go.
510 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
511 // There's no place to record types from signatures?
515 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
516 fn get_new_lifetime_name<'tcx>(
518 poly_trait_ref: ty::PolyTraitRef<'tcx>,
519 generics: &hir::Generics<'tcx>,
521 let existing_lifetimes = tcx
522 .collect_referenced_late_bound_regions(&poly_trait_ref)
525 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
526 Some(name.as_str().to_string())
531 .chain(generics.params.iter().filter_map(|param| {
532 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
533 Some(param.name.ident().as_str().to_string())
538 .collect::<FxHashSet<String>>();
540 let a_to_z_repeat_n = |n| {
541 (b'a'..=b'z').map(move |c| {
542 let mut s = '\''.to_string();
543 s.extend(std::iter::repeat(char::from(c)).take(n));
548 // If all single char lifetime names are present, we wrap around and double the chars.
549 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
552 /// Returns the predicates defined on `item_def_id` of the form
553 /// `X: Foo` where `X` is the type parameter `def_id`.
554 fn type_param_predicates(
556 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
557 ) -> ty::GenericPredicates<'_> {
560 // In the AST, bounds can derive from two places. Either
561 // written inline like `<T: Foo>` or in a where-clause like
564 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
565 let param_owner = tcx.hir().ty_param_owner(param_id);
566 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
567 let generics = tcx.generics_of(param_owner_def_id);
568 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
569 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
571 // Don't look for bounds where the type parameter isn't in scope.
572 let parent = if item_def_id == param_owner_def_id.to_def_id() {
575 tcx.generics_of(item_def_id).parent
578 let mut result = parent
580 let icx = ItemCtxt::new(tcx, parent);
581 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
583 .unwrap_or_default();
584 let mut extend = None;
586 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
587 let ast_generics = match tcx.hir().get(item_hir_id) {
588 Node::TraitItem(item) => &item.generics,
590 Node::ImplItem(item) => &item.generics,
592 Node::Item(item) => {
594 ItemKind::Fn(.., ref generics, _)
595 | ItemKind::Impl(hir::Impl { ref generics, .. })
596 | ItemKind::TyAlias(_, ref generics)
597 | ItemKind::OpaqueTy(OpaqueTy {
599 origin: hir::OpaqueTyOrigin::TyAlias,
602 | ItemKind::Enum(_, ref generics)
603 | ItemKind::Struct(_, ref generics)
604 | ItemKind::Union(_, ref generics) => generics,
605 ItemKind::Trait(_, _, ref generics, ..) => {
606 // Implied `Self: Trait` and supertrait bounds.
607 if param_id == item_hir_id {
608 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
610 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
618 Node::ForeignItem(item) => match item.kind {
619 ForeignItemKind::Fn(_, _, ref generics) => generics,
626 let icx = ItemCtxt::new(tcx, item_def_id);
627 let extra_predicates = extend.into_iter().chain(
628 icx.type_parameter_bounds_in_generics(
632 OnlySelfBounds(true),
636 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
637 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
642 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
646 impl ItemCtxt<'tcx> {
647 /// Finds bounds from `hir::Generics`. This requires scanning through the
648 /// AST. We do this to avoid having to convert *all* the bounds, which
649 /// would create artificial cycles. Instead, we can only convert the
650 /// bounds for a type parameter `X` if `X::Foo` is used.
651 fn type_parameter_bounds_in_generics(
653 ast_generics: &'tcx hir::Generics<'tcx>,
654 param_id: hir::HirId,
656 only_self_bounds: OnlySelfBounds,
657 assoc_name: Option<Ident>,
658 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
659 let from_ty_params = ast_generics
662 .filter_map(|param| match param.kind {
663 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
666 .flat_map(|bounds| bounds.iter())
667 .filter(|b| match assoc_name {
668 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
671 .flat_map(|b| predicates_from_bound(self, ty, b, ty::List::empty()));
673 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
674 let from_where_clauses = ast_generics
678 .filter_map(|wp| match *wp {
679 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
683 let bt = if bp.is_param_bound(param_def_id) {
685 } else if !only_self_bounds.0 {
686 Some(self.to_ty(bp.bounded_ty))
690 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
694 .filter(|b| match assoc_name {
695 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
698 .filter_map(move |b| bt.map(|bt| (bt, b, bvars)))
700 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars));
702 from_ty_params.chain(from_where_clauses).collect()
705 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
706 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
709 hir::GenericBound::Trait(poly_trait_ref, _) => {
710 let trait_ref = &poly_trait_ref.trait_ref;
711 if let Some(trait_did) = trait_ref.trait_def_id() {
712 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
722 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
723 let it = tcx.hir().item(item_id);
724 debug!("convert: item {} with id {}", it.ident, it.hir_id());
725 let def_id = item_id.def_id;
728 // These don't define types.
729 hir::ItemKind::ExternCrate(_)
730 | hir::ItemKind::Use(..)
731 | hir::ItemKind::Macro(_)
732 | hir::ItemKind::Mod(_)
733 | hir::ItemKind::GlobalAsm(_) => {}
734 hir::ItemKind::ForeignMod { items, .. } => {
736 let item = tcx.hir().foreign_item(item.id);
737 tcx.ensure().generics_of(item.def_id);
738 tcx.ensure().type_of(item.def_id);
739 tcx.ensure().predicates_of(item.def_id);
741 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
742 hir::ForeignItemKind::Static(..) => {
743 let mut visitor = PlaceholderHirTyCollector::default();
744 visitor.visit_foreign_item(item);
745 placeholder_type_error(
759 hir::ItemKind::Enum(ref enum_definition, _) => {
760 tcx.ensure().generics_of(def_id);
761 tcx.ensure().type_of(def_id);
762 tcx.ensure().predicates_of(def_id);
763 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
765 hir::ItemKind::Impl { .. } => {
766 tcx.ensure().generics_of(def_id);
767 tcx.ensure().type_of(def_id);
768 tcx.ensure().impl_trait_ref(def_id);
769 tcx.ensure().predicates_of(def_id);
771 hir::ItemKind::Trait(..) => {
772 tcx.ensure().generics_of(def_id);
773 tcx.ensure().trait_def(def_id);
774 tcx.at(it.span).super_predicates_of(def_id);
775 tcx.ensure().predicates_of(def_id);
777 hir::ItemKind::TraitAlias(..) => {
778 tcx.ensure().generics_of(def_id);
779 tcx.at(it.span).super_predicates_of(def_id);
780 tcx.ensure().predicates_of(def_id);
782 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
783 tcx.ensure().generics_of(def_id);
784 tcx.ensure().type_of(def_id);
785 tcx.ensure().predicates_of(def_id);
787 for f in struct_def.fields() {
788 let def_id = tcx.hir().local_def_id(f.hir_id);
789 tcx.ensure().generics_of(def_id);
790 tcx.ensure().type_of(def_id);
791 tcx.ensure().predicates_of(def_id);
794 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
795 convert_variant_ctor(tcx, ctor_hir_id);
799 // Desugared from `impl Trait`, so visited by the function's return type.
800 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
801 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
805 // Don't call `type_of` on opaque types, since that depends on type
806 // checking function bodies. `check_item_type` ensures that it's called
808 hir::ItemKind::OpaqueTy(..) => {
809 tcx.ensure().generics_of(def_id);
810 tcx.ensure().predicates_of(def_id);
811 tcx.ensure().explicit_item_bounds(def_id);
813 hir::ItemKind::TyAlias(..)
814 | hir::ItemKind::Static(..)
815 | hir::ItemKind::Const(..)
816 | hir::ItemKind::Fn(..) => {
817 tcx.ensure().generics_of(def_id);
818 tcx.ensure().type_of(def_id);
819 tcx.ensure().predicates_of(def_id);
821 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
822 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
823 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
824 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
825 if let hir::TyKind::TraitObject(..) = ty.kind {
826 let mut visitor = PlaceholderHirTyCollector::default();
827 visitor.visit_item(it);
828 placeholder_type_error(
845 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
846 let trait_item = tcx.hir().trait_item(trait_item_id);
847 tcx.ensure().generics_of(trait_item_id.def_id);
849 match trait_item.kind {
850 hir::TraitItemKind::Fn(..) => {
851 tcx.ensure().type_of(trait_item_id.def_id);
852 tcx.ensure().fn_sig(trait_item_id.def_id);
855 hir::TraitItemKind::Const(.., Some(_)) => {
856 tcx.ensure().type_of(trait_item_id.def_id);
859 hir::TraitItemKind::Const(..) => {
860 tcx.ensure().type_of(trait_item_id.def_id);
861 // Account for `const C: _;`.
862 let mut visitor = PlaceholderHirTyCollector::default();
863 visitor.visit_trait_item(trait_item);
864 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
867 hir::TraitItemKind::Type(_, Some(_)) => {
868 tcx.ensure().item_bounds(trait_item_id.def_id);
869 tcx.ensure().type_of(trait_item_id.def_id);
870 // Account for `type T = _;`.
871 let mut visitor = PlaceholderHirTyCollector::default();
872 visitor.visit_trait_item(trait_item);
873 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
876 hir::TraitItemKind::Type(_, None) => {
877 tcx.ensure().item_bounds(trait_item_id.def_id);
878 // #74612: Visit and try to find bad placeholders
879 // even if there is no concrete type.
880 let mut visitor = PlaceholderHirTyCollector::default();
881 visitor.visit_trait_item(trait_item);
883 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
887 tcx.ensure().predicates_of(trait_item_id.def_id);
890 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
891 let def_id = impl_item_id.def_id;
892 tcx.ensure().generics_of(def_id);
893 tcx.ensure().type_of(def_id);
894 tcx.ensure().predicates_of(def_id);
895 let impl_item = tcx.hir().impl_item(impl_item_id);
896 match impl_item.kind {
897 hir::ImplItemKind::Fn(..) => {
898 tcx.ensure().fn_sig(def_id);
900 hir::ImplItemKind::TyAlias(_) => {
901 // Account for `type T = _;`
902 let mut visitor = PlaceholderHirTyCollector::default();
903 visitor.visit_impl_item(impl_item);
905 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
907 hir::ImplItemKind::Const(..) => {}
911 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
912 let def_id = tcx.hir().local_def_id(ctor_id);
913 tcx.ensure().generics_of(def_id);
914 tcx.ensure().type_of(def_id);
915 tcx.ensure().predicates_of(def_id);
918 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
919 let def = tcx.adt_def(def_id);
920 let repr_type = def.repr.discr_type();
921 let initial = repr_type.initial_discriminant(tcx);
922 let mut prev_discr = None::<Discr<'_>>;
924 // fill the discriminant values and field types
925 for variant in variants {
926 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
928 if let Some(ref e) = variant.disr_expr {
929 let expr_did = tcx.hir().local_def_id(e.hir_id);
930 def.eval_explicit_discr(tcx, expr_did.to_def_id())
931 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
934 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
937 format!("overflowed on value after {}", prev_discr.unwrap()),
940 "explicitly set `{} = {}` if that is desired outcome",
941 variant.ident, wrapped_discr
946 .unwrap_or(wrapped_discr),
949 for f in variant.data.fields() {
950 let def_id = tcx.hir().local_def_id(f.hir_id);
951 tcx.ensure().generics_of(def_id);
952 tcx.ensure().type_of(def_id);
953 tcx.ensure().predicates_of(def_id);
956 // Convert the ctor, if any. This also registers the variant as
958 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
959 convert_variant_ctor(tcx, ctor_hir_id);
966 variant_did: Option<LocalDefId>,
967 ctor_did: Option<LocalDefId>,
969 discr: ty::VariantDiscr,
970 def: &hir::VariantData<'_>,
971 adt_kind: ty::AdtKind,
972 parent_did: LocalDefId,
973 ) -> ty::VariantDef {
974 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
979 let fid = tcx.hir().local_def_id(f.hir_id);
980 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
981 if let Some(prev_span) = dup_span {
982 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
988 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
991 ty::FieldDef { did: fid.to_def_id(), ident: f.ident, vis: tcx.visibility(fid) }
994 let recovered = match def {
995 hir::VariantData::Struct(_, r) => *r,
1000 variant_did.map(LocalDefId::to_def_id),
1001 ctor_did.map(LocalDefId::to_def_id),
1004 CtorKind::from_hir(def),
1006 parent_did.to_def_id(),
1008 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1009 || variant_did.map_or(false, |variant_did| {
1010 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1015 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
1018 let def_id = def_id.expect_local();
1019 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1020 let item = match tcx.hir().get(hir_id) {
1021 Node::Item(item) => item,
1025 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1026 let (kind, variants) = match item.kind {
1027 ItemKind::Enum(ref def, _) => {
1028 let mut distance_from_explicit = 0;
1033 let variant_did = Some(tcx.hir().local_def_id(v.id));
1035 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1037 let discr = if let Some(ref e) = v.disr_expr {
1038 distance_from_explicit = 0;
1039 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1041 ty::VariantDiscr::Relative(distance_from_explicit)
1043 distance_from_explicit += 1;
1058 (AdtKind::Enum, variants)
1060 ItemKind::Struct(ref def, _) => {
1061 let variant_did = None::<LocalDefId>;
1062 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1064 let variants = std::iter::once(convert_variant(
1069 ty::VariantDiscr::Relative(0),
1076 (AdtKind::Struct, variants)
1078 ItemKind::Union(ref def, _) => {
1079 let variant_did = None;
1080 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1082 let variants = std::iter::once(convert_variant(
1087 ty::VariantDiscr::Relative(0),
1094 (AdtKind::Union, variants)
1098 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1101 /// Ensures that the super-predicates of the trait with a `DefId`
1102 /// of `trait_def_id` are converted and stored. This also ensures that
1103 /// the transitive super-predicates are converted.
1104 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1105 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1106 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1109 /// Ensures that the super-predicates of the trait with a `DefId`
1110 /// of `trait_def_id` are converted and stored. This also ensures that
1111 /// the transitive super-predicates are converted.
1112 fn super_predicates_that_define_assoc_type(
1114 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1115 ) -> ty::GenericPredicates<'_> {
1117 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1118 trait_def_id, assoc_name
1120 if trait_def_id.is_local() {
1121 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1122 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1124 let item = match tcx.hir().get(trait_hir_id) {
1125 Node::Item(item) => item,
1126 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
1129 let (generics, bounds) = match item.kind {
1130 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1131 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1132 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1135 let icx = ItemCtxt::new(tcx, trait_def_id);
1137 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1138 let self_param_ty = tcx.types.self_param;
1139 let superbounds1 = if let Some(assoc_name) = assoc_name {
1140 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1147 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1150 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1152 // Convert any explicit superbounds in the where-clause,
1153 // e.g., `trait Foo where Self: Bar`.
1154 // In the case of trait aliases, however, we include all bounds in the where-clause,
1155 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1156 // as one of its "superpredicates".
1157 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1158 let superbounds2 = icx.type_parameter_bounds_in_generics(
1162 OnlySelfBounds(!is_trait_alias),
1166 // Combine the two lists to form the complete set of superbounds:
1167 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1169 // Now require that immediate supertraits are converted,
1170 // which will, in turn, reach indirect supertraits.
1171 if assoc_name.is_none() {
1172 // Now require that immediate supertraits are converted,
1173 // which will, in turn, reach indirect supertraits.
1174 for &(pred, span) in superbounds {
1175 debug!("superbound: {:?}", pred);
1176 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1177 tcx.at(span).super_predicates_of(bound.def_id());
1182 ty::GenericPredicates { parent: None, predicates: superbounds }
1184 // if `assoc_name` is None, then the query should've been redirected to an
1185 // external provider
1186 assert!(assoc_name.is_some());
1187 tcx.super_predicates_of(trait_def_id)
1191 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1192 let item = tcx.hir().expect_item(def_id.expect_local());
1194 let (is_auto, unsafety) = match item.kind {
1195 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
1196 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
1197 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1200 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1201 if paren_sugar && !tcx.features().unboxed_closures {
1205 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1206 which traits can use parenthetical notation",
1208 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1212 let is_marker = tcx.has_attr(def_id, sym::marker);
1213 let skip_array_during_method_dispatch =
1214 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1215 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1216 ty::trait_def::TraitSpecializationKind::Marker
1217 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1218 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1220 ty::trait_def::TraitSpecializationKind::None
1222 let def_path_hash = tcx.def_path_hash(def_id);
1229 skip_array_during_method_dispatch,
1235 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1236 struct LateBoundRegionsDetector<'tcx> {
1238 outer_index: ty::DebruijnIndex,
1239 has_late_bound_regions: Option<Span>,
1242 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1243 type Map = intravisit::ErasedMap<'tcx>;
1245 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1246 NestedVisitorMap::None
1249 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1250 if self.has_late_bound_regions.is_some() {
1254 hir::TyKind::BareFn(..) => {
1255 self.outer_index.shift_in(1);
1256 intravisit::walk_ty(self, ty);
1257 self.outer_index.shift_out(1);
1259 _ => intravisit::walk_ty(self, ty),
1263 fn visit_poly_trait_ref(
1265 tr: &'tcx hir::PolyTraitRef<'tcx>,
1266 m: hir::TraitBoundModifier,
1268 if self.has_late_bound_regions.is_some() {
1271 self.outer_index.shift_in(1);
1272 intravisit::walk_poly_trait_ref(self, tr, m);
1273 self.outer_index.shift_out(1);
1276 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1277 if self.has_late_bound_regions.is_some() {
1281 match self.tcx.named_region(lt.hir_id) {
1282 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1284 rl::Region::LateBound(debruijn, _, _, _)
1285 | rl::Region::LateBoundAnon(debruijn, _, _),
1286 ) if debruijn < self.outer_index => {}
1288 rl::Region::LateBound(..)
1289 | rl::Region::LateBoundAnon(..)
1290 | rl::Region::Free(..),
1293 self.has_late_bound_regions = Some(lt.span);
1299 fn has_late_bound_regions<'tcx>(
1301 generics: &'tcx hir::Generics<'tcx>,
1302 decl: &'tcx hir::FnDecl<'tcx>,
1304 let mut visitor = LateBoundRegionsDetector {
1306 outer_index: ty::INNERMOST,
1307 has_late_bound_regions: None,
1309 for param in generics.params {
1310 if let GenericParamKind::Lifetime { .. } = param.kind {
1311 if tcx.is_late_bound(param.hir_id) {
1312 return Some(param.span);
1316 visitor.visit_fn_decl(decl);
1317 visitor.has_late_bound_regions
1321 Node::TraitItem(item) => match item.kind {
1322 hir::TraitItemKind::Fn(ref sig, _) => {
1323 has_late_bound_regions(tcx, &item.generics, sig.decl)
1327 Node::ImplItem(item) => match item.kind {
1328 hir::ImplItemKind::Fn(ref sig, _) => {
1329 has_late_bound_regions(tcx, &item.generics, sig.decl)
1333 Node::ForeignItem(item) => match item.kind {
1334 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1335 has_late_bound_regions(tcx, generics, fn_decl)
1339 Node::Item(item) => match item.kind {
1340 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1341 has_late_bound_regions(tcx, generics, sig.decl)
1349 struct AnonConstInParamTyDetector {
1351 found_anon_const_in_param_ty: bool,
1355 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1356 type Map = intravisit::ErasedMap<'v>;
1358 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1359 NestedVisitorMap::None
1362 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1363 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1364 let prev = self.in_param_ty;
1365 self.in_param_ty = true;
1367 self.in_param_ty = prev;
1371 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1372 if self.in_param_ty && self.ct == c.hir_id {
1373 self.found_anon_const_in_param_ty = true;
1375 intravisit::walk_anon_const(self, c)
1380 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1383 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1385 let node = tcx.hir().get(hir_id);
1386 let parent_def_id = match node {
1388 | Node::TraitItem(_)
1391 | Node::Field(_) => {
1392 let parent_id = tcx.hir().get_parent_item(hir_id);
1393 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1395 // FIXME(#43408) always enable this once `lazy_normalization` is
1396 // stable enough and does not need a feature gate anymore.
1397 Node::AnonConst(_) => {
1398 let parent_id = tcx.hir().get_parent_item(hir_id);
1399 let parent_def_id = tcx.hir().local_def_id(parent_id);
1401 let mut in_param_ty = false;
1402 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1403 if let Some(generics) = node.generics() {
1404 let mut visitor = AnonConstInParamTyDetector {
1406 found_anon_const_in_param_ty: false,
1410 visitor.visit_generics(generics);
1411 in_param_ty = visitor.found_anon_const_in_param_ty;
1417 // We do not allow generic parameters in anon consts if we are inside
1418 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1420 } else if tcx.lazy_normalization() {
1421 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1422 // If the def_id we are calling generics_of on is an anon ct default i.e:
1424 // struct Foo<const N: usize = { .. }>;
1425 // ^^^ ^ ^^^^^^ def id of this anon const
1429 // then we only want to return generics for params to the left of `N`. If we don't do that we
1430 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1432 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1433 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1434 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1436 // We fix this by having this function return the parent's generics ourselves and truncating the
1437 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1439 // For the above code example that means we want `substs: []`
1440 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1441 // the def id of the `{ N + 1 }` anon const
1442 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1444 // This has some implications for how we get the predicates available to the anon const
1445 // see `explicit_predicates_of` for more information on this
1446 let generics = tcx.generics_of(parent_def_id.to_def_id());
1447 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1448 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1449 // In the above example this would be .params[..N#0]
1450 let params = generics.params[..param_def_idx as usize].to_owned();
1451 let param_def_id_to_index =
1452 params.iter().map(|param| (param.def_id, param.index)).collect();
1454 return ty::Generics {
1455 // we set the parent of these generics to be our parent's parent so that we
1456 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1457 // struct Foo<const N: usize, const M: usize = { ... }>;
1458 parent: generics.parent,
1459 parent_count: generics.parent_count,
1461 param_def_id_to_index,
1462 has_self: generics.has_self,
1463 has_late_bound_regions: generics.has_late_bound_regions,
1467 // HACK(eddyb) this provides the correct generics when
1468 // `feature(generic_const_expressions)` is enabled, so that const expressions
1469 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1471 // Note that we do not supply the parent generics when using
1472 // `min_const_generics`.
1473 Some(parent_def_id.to_def_id())
1475 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1477 // HACK(eddyb) this provides the correct generics for repeat
1478 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1479 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1480 // as they shouldn't be able to cause query cycle errors.
1481 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1482 | Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1483 if constant.hir_id == hir_id =>
1485 Some(parent_def_id.to_def_id())
1487 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1488 Some(tcx.typeck_root_def_id(def_id))
1494 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1495 Some(tcx.typeck_root_def_id(def_id))
1497 Node::Item(item) => match item.kind {
1498 ItemKind::OpaqueTy(hir::OpaqueTy {
1500 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1502 }) => Some(fn_def_id.to_def_id()),
1503 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1504 let parent_id = tcx.hir().get_parent_item(hir_id);
1505 assert!(parent_id != hir_id && parent_id != CRATE_HIR_ID);
1506 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1507 // Opaque types are always nested within another item, and
1508 // inherit the generics of the item.
1509 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1516 let mut opt_self = None;
1517 let mut allow_defaults = false;
1519 let no_generics = hir::Generics::empty();
1520 let ast_generics = match node {
1521 Node::TraitItem(item) => &item.generics,
1523 Node::ImplItem(item) => &item.generics,
1525 Node::Item(item) => {
1527 ItemKind::Fn(.., ref generics, _)
1528 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1530 ItemKind::TyAlias(_, ref generics)
1531 | ItemKind::Enum(_, ref generics)
1532 | ItemKind::Struct(_, ref generics)
1533 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1534 | ItemKind::Union(_, ref generics) => {
1535 allow_defaults = true;
1539 ItemKind::Trait(_, _, ref generics, ..)
1540 | ItemKind::TraitAlias(ref generics, ..) => {
1541 // Add in the self type parameter.
1543 // Something of a hack: use the node id for the trait, also as
1544 // the node id for the Self type parameter.
1545 let param_id = item.def_id;
1547 opt_self = Some(ty::GenericParamDef {
1549 name: kw::SelfUpper,
1550 def_id: param_id.to_def_id(),
1551 pure_wrt_drop: false,
1552 kind: ty::GenericParamDefKind::Type {
1554 object_lifetime_default: rl::Set1::Empty,
1559 allow_defaults = true;
1567 Node::ForeignItem(item) => match item.kind {
1568 ForeignItemKind::Static(..) => &no_generics,
1569 ForeignItemKind::Fn(_, _, ref generics) => generics,
1570 ForeignItemKind::Type => &no_generics,
1576 let has_self = opt_self.is_some();
1577 let mut parent_has_self = false;
1578 let mut own_start = has_self as u32;
1579 let parent_count = parent_def_id.map_or(0, |def_id| {
1580 let generics = tcx.generics_of(def_id);
1582 parent_has_self = generics.has_self;
1583 own_start = generics.count() as u32;
1584 generics.parent_count + generics.params.len()
1587 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1589 if let Some(opt_self) = opt_self {
1590 params.push(opt_self);
1593 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1594 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1595 name: param.name.ident().name,
1596 index: own_start + i as u32,
1597 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1598 pure_wrt_drop: param.pure_wrt_drop,
1599 kind: ty::GenericParamDefKind::Lifetime,
1602 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1604 // Now create the real type and const parameters.
1605 let type_start = own_start - has_self as u32 + params.len() as u32;
1608 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1609 GenericParamKind::Lifetime { .. } => None,
1610 GenericParamKind::Type { ref default, synthetic, .. } => {
1611 if !allow_defaults && default.is_some() {
1612 if !tcx.features().default_type_parameter_fallback {
1613 tcx.struct_span_lint_hir(
1614 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1619 "defaults for type parameters are only allowed in \
1620 `struct`, `enum`, `type`, or `trait` definitions",
1628 let kind = ty::GenericParamDefKind::Type {
1629 has_default: default.is_some(),
1630 object_lifetime_default: object_lifetime_defaults
1632 .map_or(rl::Set1::Empty, |o| o[i]),
1636 let param_def = ty::GenericParamDef {
1637 index: type_start + i as u32,
1638 name: param.name.ident().name,
1639 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1640 pure_wrt_drop: param.pure_wrt_drop,
1646 GenericParamKind::Const { default, .. } => {
1647 if !allow_defaults && default.is_some() {
1650 "defaults for const parameters are only allowed in \
1651 `struct`, `enum`, `type`, or `trait` definitions",
1655 let param_def = ty::GenericParamDef {
1656 index: type_start + i as u32,
1657 name: param.name.ident().name,
1658 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1659 pure_wrt_drop: param.pure_wrt_drop,
1660 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1667 // provide junk type parameter defs - the only place that
1668 // cares about anything but the length is instantiation,
1669 // and we don't do that for closures.
1670 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1671 let dummy_args = if gen.is_some() {
1672 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1674 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1677 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1678 index: type_start + i as u32,
1679 name: Symbol::intern(arg),
1681 pure_wrt_drop: false,
1682 kind: ty::GenericParamDefKind::Type {
1684 object_lifetime_default: rl::Set1::Empty,
1690 // provide junk type parameter defs for const blocks.
1691 if let Node::AnonConst(_) = node {
1692 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1693 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1694 params.push(ty::GenericParamDef {
1696 name: Symbol::intern("<const_ty>"),
1698 pure_wrt_drop: false,
1699 kind: ty::GenericParamDefKind::Type {
1701 object_lifetime_default: rl::Set1::Empty,
1708 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1711 parent: parent_def_id,
1714 param_def_id_to_index,
1715 has_self: has_self || parent_has_self,
1716 has_late_bound_regions: has_late_bound_regions(tcx, node),
1720 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1721 generic_args.iter().any(|arg| match arg {
1722 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1723 hir::GenericArg::Infer(_) => true,
1728 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1729 /// use inference to provide suggestions for the appropriate type if possible.
1730 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1734 Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
1735 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1736 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1737 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1738 Path(hir::QPath::TypeRelative(ty, segment)) => {
1739 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1741 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1742 ty_opt.map_or(false, is_suggestable_infer_ty)
1743 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1749 pub fn get_infer_ret_ty(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1750 if let hir::FnRetTy::Return(ty) = output {
1751 if is_suggestable_infer_ty(ty) {
1758 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1759 use rustc_hir::Node::*;
1762 let def_id = def_id.expect_local();
1763 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1765 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1767 match tcx.hir().get(hir_id) {
1768 TraitItem(hir::TraitItem {
1769 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1774 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1775 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1776 match get_infer_ret_ty(&sig.decl.output) {
1778 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1779 // Typeck doesn't expect erased regions to be returned from `type_of`.
1780 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match r {
1781 ty::ReErased => tcx.lifetimes.re_static,
1784 let fn_sig = ty::Binder::dummy(fn_sig);
1786 let mut visitor = PlaceholderHirTyCollector::default();
1787 visitor.visit_ty(ty);
1788 let mut diag = bad_placeholder_type(tcx, visitor.0, "return type");
1789 let ret_ty = fn_sig.skip_binder().output();
1790 if !ret_ty.references_error() {
1791 if !ret_ty.is_closure() {
1792 let ret_ty_str = match ret_ty.kind() {
1793 // Suggest a function pointer return type instead of a unique function definition
1794 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1796 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1797 _ => ret_ty.to_string(),
1799 diag.span_suggestion(
1801 "replace with the correct return type",
1803 Applicability::MaybeIncorrect,
1806 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1807 // to prevent the user from getting a papercut while trying to use the unique closure
1808 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1809 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1810 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1817 None => <dyn AstConv<'_>>::ty_of_fn(
1820 sig.header.unsafety,
1830 TraitItem(hir::TraitItem {
1831 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1835 }) => <dyn AstConv<'_>>::ty_of_fn(
1846 ForeignItem(&hir::ForeignItem {
1847 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1849 let abi = tcx.hir().get_foreign_abi(hir_id);
1850 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1853 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1854 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id).to_def_id());
1856 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1857 ty::Binder::dummy(tcx.mk_fn_sig(
1861 hir::Unsafety::Normal,
1866 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1867 // Closure signatures are not like other function
1868 // signatures and cannot be accessed through `fn_sig`. For
1869 // example, a closure signature excludes the `self`
1870 // argument. In any case they are embedded within the
1871 // closure type as part of the `ClosureSubsts`.
1873 // To get the signature of a closure, you should use the
1874 // `sig` method on the `ClosureSubsts`:
1876 // substs.as_closure().sig(def_id, tcx)
1878 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1883 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1888 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1889 let icx = ItemCtxt::new(tcx, def_id);
1890 match tcx.hir().expect_item(def_id.expect_local()).kind {
1891 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1892 let selfty = tcx.type_of(def_id);
1893 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1899 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1900 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1901 let item = tcx.hir().expect_item(def_id.expect_local());
1903 hir::ItemKind::Impl(hir::Impl {
1904 polarity: hir::ImplPolarity::Negative(span),
1908 if is_rustc_reservation {
1909 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
1910 tcx.sess.span_err(span, "reservation impls can't be negative");
1912 ty::ImplPolarity::Negative
1914 hir::ItemKind::Impl(hir::Impl {
1915 polarity: hir::ImplPolarity::Positive,
1919 if is_rustc_reservation {
1920 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1922 ty::ImplPolarity::Positive
1924 hir::ItemKind::Impl(hir::Impl {
1925 polarity: hir::ImplPolarity::Positive,
1929 if is_rustc_reservation {
1930 ty::ImplPolarity::Reservation
1932 ty::ImplPolarity::Positive
1935 item => bug!("impl_polarity: {:?} not an impl", item),
1939 /// Returns the early-bound lifetimes declared in this generics
1940 /// listing. For anything other than fns/methods, this is just all
1941 /// the lifetimes that are declared. For fns or methods, we have to
1942 /// screen out those that do not appear in any where-clauses etc using
1943 /// `resolve_lifetime::early_bound_lifetimes`.
1944 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1946 generics: &'a hir::Generics<'a>,
1947 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1948 generics.params.iter().filter(move |param| match param.kind {
1949 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1954 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1955 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1956 /// inferred constraints concerning which regions outlive other regions.
1957 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1958 debug!("predicates_defined_on({:?})", def_id);
1959 let mut result = tcx.explicit_predicates_of(def_id);
1960 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1961 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1962 if !inferred_outlives.is_empty() {
1964 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1965 def_id, inferred_outlives,
1967 if result.predicates.is_empty() {
1968 result.predicates = inferred_outlives;
1970 result.predicates = tcx
1972 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1976 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1980 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1981 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1982 /// `Self: Trait` predicates for traits.
1983 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1984 let mut result = tcx.predicates_defined_on(def_id);
1986 if tcx.is_trait(def_id) {
1987 // For traits, add `Self: Trait` predicate. This is
1988 // not part of the predicates that a user writes, but it
1989 // is something that one must prove in order to invoke a
1990 // method or project an associated type.
1992 // In the chalk setup, this predicate is not part of the
1993 // "predicates" for a trait item. But it is useful in
1994 // rustc because if you directly (e.g.) invoke a trait
1995 // method like `Trait::method(...)`, you must naturally
1996 // prove that the trait applies to the types that were
1997 // used, and adding the predicate into this list ensures
1998 // that this is done.
2000 // We use a DUMMY_SP here as a way to signal trait bounds that come
2001 // from the trait itself that *shouldn't* be shown as the source of
2002 // an obligation and instead be skipped. Otherwise we'd use
2003 // `tcx.def_span(def_id);`
2004 let span = rustc_span::DUMMY_SP;
2006 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2007 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2011 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2015 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2016 /// N.B., this does not include any implied/inferred constraints.
2017 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2020 debug!("explicit_predicates_of(def_id={:?})", def_id);
2022 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2023 let node = tcx.hir().get(hir_id);
2025 let mut is_trait = None;
2026 let mut is_default_impl_trait = None;
2028 let icx = ItemCtxt::new(tcx, def_id);
2030 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2032 // We use an `IndexSet` to preserves order of insertion.
2033 // Preserving the order of insertion is important here so as not to break UI tests.
2034 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2036 let ast_generics = match node {
2037 Node::TraitItem(item) => &item.generics,
2039 Node::ImplItem(item) => &item.generics,
2041 Node::Item(item) => {
2043 ItemKind::Impl(ref impl_) => {
2044 if impl_.defaultness.is_default() {
2045 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2049 ItemKind::Fn(.., ref generics, _)
2050 | ItemKind::TyAlias(_, ref generics)
2051 | ItemKind::Enum(_, ref generics)
2052 | ItemKind::Struct(_, ref generics)
2053 | ItemKind::Union(_, ref generics) => generics,
2055 ItemKind::Trait(_, _, ref generics, ..) => {
2056 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2059 ItemKind::TraitAlias(ref generics, _) => {
2060 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2063 ItemKind::OpaqueTy(OpaqueTy {
2064 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2067 // return-position impl trait
2069 // We don't inherit predicates from the parent here:
2070 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2071 // then the return type is `f::<'static, T>::{{opaque}}`.
2073 // If we inherited the predicates of `f` then we would
2074 // require that `T: 'static` to show that the return
2075 // type is well-formed.
2077 // The only way to have something with this opaque type
2078 // is from the return type of the containing function,
2079 // which will ensure that the function's predicates
2081 return ty::GenericPredicates { parent: None, predicates: &[] };
2083 ItemKind::OpaqueTy(OpaqueTy {
2085 origin: hir::OpaqueTyOrigin::TyAlias,
2088 // type-alias impl trait
2096 Node::ForeignItem(item) => match item.kind {
2097 ForeignItemKind::Static(..) => NO_GENERICS,
2098 ForeignItemKind::Fn(_, _, ref generics) => generics,
2099 ForeignItemKind::Type => NO_GENERICS,
2105 let generics = tcx.generics_of(def_id);
2106 let parent_count = generics.parent_count as u32;
2107 let has_own_self = generics.has_self && parent_count == 0;
2109 // Below we'll consider the bounds on the type parameters (including `Self`)
2110 // and the explicit where-clauses, but to get the full set of predicates
2111 // on a trait we need to add in the supertrait bounds and bounds found on
2112 // associated types.
2113 if let Some(_trait_ref) = is_trait {
2114 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2117 // In default impls, we can assume that the self type implements
2118 // the trait. So in:
2120 // default impl Foo for Bar { .. }
2122 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2123 // (see below). Recall that a default impl is not itself an impl, but rather a
2124 // set of defaults that can be incorporated into another impl.
2125 if let Some(trait_ref) = is_default_impl_trait {
2126 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2129 // Collect the region predicates that were declared inline as
2130 // well. In the case of parameters declared on a fn or method, we
2131 // have to be careful to only iterate over early-bound regions.
2132 let mut index = parent_count + has_own_self as u32;
2133 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2134 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2135 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2137 name: param.name.ident().name,
2142 GenericParamKind::Lifetime { .. } => {
2143 param.bounds.iter().for_each(|bound| match bound {
2144 hir::GenericBound::Outlives(lt) => {
2145 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2146 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2147 predicates.insert((outlives.to_predicate(tcx), lt.span));
2156 // Collect the predicates that were written inline by the user on each
2157 // type parameter (e.g., `<T: Foo>`).
2158 for param in ast_generics.params {
2160 // We already dealt with early bound lifetimes above.
2161 GenericParamKind::Lifetime { .. } => (),
2162 GenericParamKind::Type { .. } => {
2163 let name = param.name.ident().name;
2164 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2167 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2168 // Params are implicitly sized unless a `?Sized` bound is found
2169 <dyn AstConv<'_>>::add_implicitly_sized(
2173 Some((param.hir_id, ast_generics.where_clause.predicates)),
2176 predicates.extend(bounds.predicates(tcx, param_ty));
2178 GenericParamKind::Const { .. } => {
2179 // Bounds on const parameters are currently not possible.
2180 debug_assert!(param.bounds.is_empty());
2186 // Add in the bounds that appear in the where-clause.
2187 let where_clause = &ast_generics.where_clause;
2188 for predicate in where_clause.predicates {
2190 hir::WherePredicate::BoundPredicate(bound_pred) => {
2191 let ty = icx.to_ty(bound_pred.bounded_ty);
2192 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2194 // Keep the type around in a dummy predicate, in case of no bounds.
2195 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2196 // is still checked for WF.
2197 if bound_pred.bounds.is_empty() {
2198 if let ty::Param(_) = ty.kind() {
2199 // This is a `where T:`, which can be in the HIR from the
2200 // transformation that moves `?Sized` to `T`'s declaration.
2201 // We can skip the predicate because type parameters are
2202 // trivially WF, but also we *should*, to avoid exposing
2203 // users who never wrote `where Type:,` themselves, to
2204 // compiler/tooling bugs from not handling WF predicates.
2206 let span = bound_pred.bounded_ty.span;
2207 let re_root_empty = tcx.lifetimes.re_root_empty;
2208 let predicate = ty::Binder::bind_with_vars(
2209 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2215 predicates.insert((predicate.to_predicate(tcx), span));
2219 let mut bounds = Bounds::default();
2220 <dyn AstConv<'_>>::add_bounds(
2223 bound_pred.bounds.iter(),
2227 predicates.extend(bounds.predicates(tcx, ty));
2230 hir::WherePredicate::RegionPredicate(region_pred) => {
2231 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2232 predicates.extend(region_pred.bounds.iter().map(|bound| {
2233 let (r2, span) = match bound {
2234 hir::GenericBound::Outlives(lt) => {
2235 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2239 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2240 ty::OutlivesPredicate(r1, r2),
2242 .to_predicate(icx.tcx);
2248 hir::WherePredicate::EqPredicate(..) => {
2254 if tcx.features().generic_const_exprs {
2255 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2258 let mut predicates: Vec<_> = predicates.into_iter().collect();
2260 // Subtle: before we store the predicates into the tcx, we
2261 // sort them so that predicates like `T: Foo<Item=U>` come
2262 // before uses of `U`. This avoids false ambiguity errors
2263 // in trait checking. See `setup_constraining_predicates`
2265 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2266 let self_ty = tcx.type_of(def_id);
2267 let trait_ref = tcx.impl_trait_ref(def_id);
2268 cgp::setup_constraining_predicates(
2272 &mut cgp::parameters_for_impl(tcx, self_ty, trait_ref),
2276 let result = ty::GenericPredicates {
2277 parent: generics.parent,
2278 predicates: tcx.arena.alloc_from_iter(predicates),
2280 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2284 fn const_evaluatable_predicates_of<'tcx>(
2287 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2288 struct ConstCollector<'tcx> {
2290 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2293 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2294 type Map = Map<'tcx>;
2296 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
2297 intravisit::NestedVisitorMap::None
2300 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2301 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2302 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2303 if let ty::ConstKind::Unevaluated(uv) = ct.val {
2304 assert_eq!(uv.promoted, None);
2305 let span = self.tcx.hir().span(c.hir_id);
2307 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2308 .to_predicate(self.tcx),
2314 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2315 // Do not look into const param defaults,
2316 // these get checked when they are actually instantiated.
2318 // We do not want the following to error:
2320 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2321 // struct Bar<const N: usize>(Foo<N, 3>);
2325 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2326 let node = tcx.hir().get(hir_id);
2328 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2329 if let hir::Node::Item(item) = node {
2330 if let hir::ItemKind::Impl(ref impl_) = item.kind {
2331 if let Some(of_trait) = &impl_.of_trait {
2332 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2333 collector.visit_trait_ref(of_trait);
2336 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2337 collector.visit_ty(impl_.self_ty);
2341 if let Some(generics) = node.generics() {
2342 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2343 collector.visit_generics(generics);
2346 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2347 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2348 collector.visit_fn_decl(fn_sig.decl);
2350 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2355 fn trait_explicit_predicates_and_bounds(
2358 ) -> ty::GenericPredicates<'_> {
2359 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2360 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2363 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2364 let def_kind = tcx.def_kind(def_id);
2365 if let DefKind::Trait = def_kind {
2366 // Remove bounds on associated types from the predicates, they will be
2367 // returned by `explicit_item_bounds`.
2368 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2369 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2371 let is_assoc_item_ty = |ty: Ty<'_>| {
2372 // For a predicate from a where clause to become a bound on an
2374 // * It must use the identity substs of the item.
2375 // * Since any generic parameters on the item are not in scope,
2376 // this means that the item is not a GAT, and its identity
2377 // substs are the same as the trait's.
2378 // * It must be an associated type for this trait (*not* a
2380 if let ty::Projection(projection) = ty.kind() {
2381 projection.substs == trait_identity_substs
2382 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2388 let predicates: Vec<_> = predicates_and_bounds
2392 .filter(|(pred, _)| match pred.kind().skip_binder() {
2393 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2394 ty::PredicateKind::Projection(proj) => {
2395 !is_assoc_item_ty(proj.projection_ty.self_ty())
2397 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2401 if predicates.len() == predicates_and_bounds.predicates.len() {
2402 predicates_and_bounds
2404 ty::GenericPredicates {
2405 parent: predicates_and_bounds.parent,
2406 predicates: tcx.arena.alloc_slice(&predicates),
2410 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2411 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2412 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2413 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2414 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2415 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2417 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2418 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2419 // ^^^ explicit_predicates_of on
2420 // parent item we dont have set as the
2421 // parent of generics returned by `generics_of`
2423 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2424 let item_id = tcx.hir().get_parent_item(hir_id);
2425 let item_def_id = tcx.hir().local_def_id(item_id).to_def_id();
2426 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2427 return tcx.explicit_predicates_of(item_def_id);
2430 gather_explicit_predicates_of(tcx, def_id)
2434 /// Converts a specific `GenericBound` from the AST into a set of
2435 /// predicates that apply to the self type. A vector is returned
2436 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2437 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2438 /// and `<T as Bar>::X == i32`).
2439 fn predicates_from_bound<'tcx>(
2440 astconv: &dyn AstConv<'tcx>,
2442 bound: &'tcx hir::GenericBound<'tcx>,
2443 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2444 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2445 let mut bounds = Bounds::default();
2446 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2447 bounds.predicates(astconv.tcx(), param_ty)
2450 fn compute_sig_of_foreign_fn_decl<'tcx>(
2453 decl: &'tcx hir::FnDecl<'tcx>,
2456 ) -> ty::PolyFnSig<'tcx> {
2457 let unsafety = if abi == abi::Abi::RustIntrinsic {
2458 intrinsic_operation_unsafety(tcx.item_name(def_id))
2460 hir::Unsafety::Unsafe
2462 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2463 let fty = <dyn AstConv<'_>>::ty_of_fn(
2464 &ItemCtxt::new(tcx, def_id),
2469 &hir::Generics::empty(),
2474 // Feature gate SIMD types in FFI, since I am not sure that the
2475 // ABIs are handled at all correctly. -huonw
2476 if abi != abi::Abi::RustIntrinsic
2477 && abi != abi::Abi::PlatformIntrinsic
2478 && !tcx.features().simd_ffi
2480 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2485 .span_to_snippet(ast_ty.span)
2486 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2491 "use of SIMD type{} in FFI is highly experimental and \
2492 may result in invalid code",
2496 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2500 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2503 if let hir::FnRetTy::Return(ref ty) = decl.output {
2504 check(ty, fty.output().skip_binder())
2511 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2512 match tcx.hir().get_if_local(def_id) {
2513 Some(Node::ForeignItem(..)) => true,
2515 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2519 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2520 match tcx.hir().get_if_local(def_id) {
2522 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2523 | Node::ForeignItem(&hir::ForeignItem {
2524 kind: hir::ForeignItemKind::Static(_, mutbl),
2529 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2533 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2534 match tcx.hir().get_if_local(def_id) {
2535 Some(Node::Expr(&rustc_hir::Expr {
2536 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2538 })) => tcx.hir().body(body_id).generator_kind(),
2540 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2544 fn from_target_feature(
2547 attr: &ast::Attribute,
2548 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2549 target_features: &mut Vec<Symbol>,
2551 let list = match attr.meta_item_list() {
2555 let bad_item = |span| {
2556 let msg = "malformed `target_feature` attribute input";
2557 let code = "enable = \"..\"".to_owned();
2559 .struct_span_err(span, msg)
2560 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2563 let rust_features = tcx.features();
2565 // Only `enable = ...` is accepted in the meta-item list.
2566 if !item.has_name(sym::enable) {
2567 bad_item(item.span());
2571 // Must be of the form `enable = "..."` (a string).
2572 let value = match item.value_str() {
2573 Some(value) => value,
2575 bad_item(item.span());
2580 // We allow comma separation to enable multiple features.
2581 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2582 let feature_gate = match supported_target_features.get(feature) {
2586 format!("the feature named `{}` is not valid for this target", feature);
2587 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2590 format!("`{}` is not valid for this target", feature),
2592 if let Some(stripped) = feature.strip_prefix('+') {
2593 let valid = supported_target_features.contains_key(stripped);
2595 err.help("consider removing the leading `+` in the feature name");
2603 // Only allow features whose feature gates have been enabled.
2604 let allowed = match feature_gate.as_ref().copied() {
2605 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2606 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2607 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2608 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2609 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2610 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2611 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2612 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2613 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2614 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2615 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2616 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2617 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2618 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2619 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2620 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2621 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2622 Some(name) => bug!("unknown target feature gate {}", name),
2625 if !allowed && id.is_local() {
2627 &tcx.sess.parse_sess,
2628 feature_gate.unwrap(),
2630 &format!("the target feature `{}` is currently unstable", feature),
2634 Some(Symbol::intern(feature))
2639 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2640 use rustc_middle::mir::mono::Linkage::*;
2642 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2643 // applicable to variable declarations and may not really make sense for
2644 // Rust code in the first place but allow them anyway and trust that the
2645 // user knows what s/he's doing. Who knows, unanticipated use cases may pop
2646 // up in the future.
2648 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2649 // and don't have to be, LLVM treats them as no-ops.
2651 "appending" => Appending,
2652 "available_externally" => AvailableExternally,
2654 "extern_weak" => ExternalWeak,
2655 "external" => External,
2656 "internal" => Internal,
2657 "linkonce" => LinkOnceAny,
2658 "linkonce_odr" => LinkOnceODR,
2659 "private" => Private,
2661 "weak_odr" => WeakODR,
2663 let span = tcx.hir().span_if_local(def_id);
2664 if let Some(span) = span {
2665 tcx.sess.span_fatal(span, "invalid linkage specified")
2667 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2673 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2674 let attrs = tcx.get_attrs(id);
2676 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2677 if tcx.should_inherit_track_caller(id) {
2678 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2681 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2682 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2683 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2684 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2688 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2690 let mut inline_span = None;
2691 let mut link_ordinal_span = None;
2692 let mut no_sanitize_span = None;
2693 for attr in attrs.iter() {
2694 if attr.has_name(sym::cold) {
2695 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2696 } else if attr.has_name(sym::rustc_allocator) {
2697 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2698 } else if attr.has_name(sym::ffi_returns_twice) {
2699 if tcx.is_foreign_item(id) {
2700 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2702 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2707 "`#[ffi_returns_twice]` may only be used on foreign functions"
2711 } else if attr.has_name(sym::ffi_pure) {
2712 if tcx.is_foreign_item(id) {
2713 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2714 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2719 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2723 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2726 // `#[ffi_pure]` is only allowed on foreign functions
2731 "`#[ffi_pure]` may only be used on foreign functions"
2735 } else if attr.has_name(sym::ffi_const) {
2736 if tcx.is_foreign_item(id) {
2737 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2739 // `#[ffi_const]` is only allowed on foreign functions
2744 "`#[ffi_const]` may only be used on foreign functions"
2748 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2749 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2750 } else if attr.has_name(sym::naked) {
2751 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2752 } else if attr.has_name(sym::no_mangle) {
2753 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2754 } else if attr.has_name(sym::no_coverage) {
2755 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2756 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2757 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2758 } else if attr.has_name(sym::used) {
2759 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2760 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2761 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2766 "`#[cmse_nonsecure_entry]` requires C ABI"
2770 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2771 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2774 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2775 } else if attr.has_name(sym::thread_local) {
2776 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2777 } else if attr.has_name(sym::track_caller) {
2778 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2779 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2782 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2784 &tcx.sess.parse_sess,
2785 sym::closure_track_caller,
2787 "`#[track_caller]` on closures is currently unstable",
2791 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2792 } else if attr.has_name(sym::export_name) {
2793 if let Some(s) = attr.value_str() {
2794 if s.as_str().contains('\0') {
2795 // `#[export_name = ...]` will be converted to a null-terminated string,
2796 // so it may not contain any null characters.
2801 "`export_name` may not contain null characters"
2805 codegen_fn_attrs.export_name = Some(s);
2807 } else if attr.has_name(sym::target_feature) {
2808 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2809 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2810 // The `#[target_feature]` attribute is allowed on
2811 // WebAssembly targets on all functions, including safe
2812 // ones. Other targets require that `#[target_feature]` is
2813 // only applied to unsafe funtions (pending the
2814 // `target_feature_11` feature) because on most targets
2815 // execution of instructions that are not supported is
2816 // considered undefined behavior. For WebAssembly which is a
2817 // 100% safe target at execution time it's not possible to
2818 // execute undefined instructions, and even if a future
2819 // feature was added in some form for this it would be a
2820 // deterministic trap. There is no undefined behavior when
2821 // executing WebAssembly so `#[target_feature]` is allowed
2822 // on safe functions (but again, only for WebAssembly)
2824 // Note that this is also allowed if `actually_rustdoc` so
2825 // if a target is documenting some wasm-specific code then
2826 // it's not spuriously denied.
2827 } else if !tcx.features().target_feature_11 {
2828 let mut err = feature_err(
2829 &tcx.sess.parse_sess,
2830 sym::target_feature_11,
2832 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2834 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2836 } else if let Some(local_id) = id.as_local() {
2837 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2840 from_target_feature(
2844 supported_target_features,
2845 &mut codegen_fn_attrs.target_features,
2847 } else if attr.has_name(sym::linkage) {
2848 if let Some(val) = attr.value_str() {
2849 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2851 } else if attr.has_name(sym::link_section) {
2852 if let Some(val) = attr.value_str() {
2853 if val.as_str().bytes().any(|b| b == 0) {
2855 "illegal null byte in link_section \
2859 tcx.sess.span_err(attr.span, &msg);
2861 codegen_fn_attrs.link_section = Some(val);
2864 } else if attr.has_name(sym::link_name) {
2865 codegen_fn_attrs.link_name = attr.value_str();
2866 } else if attr.has_name(sym::link_ordinal) {
2867 link_ordinal_span = Some(attr.span);
2868 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2869 codegen_fn_attrs.link_ordinal = ordinal;
2871 } else if attr.has_name(sym::no_sanitize) {
2872 no_sanitize_span = Some(attr.span);
2873 if let Some(list) = attr.meta_item_list() {
2874 for item in list.iter() {
2875 if item.has_name(sym::address) {
2876 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2877 } else if item.has_name(sym::cfi) {
2878 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2879 } else if item.has_name(sym::memory) {
2880 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2881 } else if item.has_name(sym::thread) {
2882 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2883 } else if item.has_name(sym::hwaddress) {
2884 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2887 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2888 .note("expected one of: `address`, `hwaddress`, `memory` or `thread`")
2893 } else if attr.has_name(sym::instruction_set) {
2894 codegen_fn_attrs.instruction_set = match attr.meta().map(|i| i.kind) {
2895 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
2896 [NestedMetaItem::MetaItem(set)] => {
2898 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
2899 match segments.as_slice() {
2900 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
2901 if !tcx.sess.target.has_thumb_interworking {
2903 tcx.sess.diagnostic(),
2906 "target does not support `#[instruction_set]`"
2910 } else if segments[1] == sym::a32 {
2911 Some(InstructionSetAttr::ArmA32)
2912 } else if segments[1] == sym::t32 {
2913 Some(InstructionSetAttr::ArmT32)
2920 tcx.sess.diagnostic(),
2923 "invalid instruction set specified",
2932 tcx.sess.diagnostic(),
2935 "`#[instruction_set]` requires an argument"
2942 tcx.sess.diagnostic(),
2945 "cannot specify more than one instruction set"
2953 tcx.sess.diagnostic(),
2956 "must specify an instruction set"
2962 } else if attr.has_name(sym::repr) {
2963 codegen_fn_attrs.alignment = match attr.meta_item_list() {
2964 Some(items) => match items.as_slice() {
2965 [item] => match item.name_value_literal() {
2966 Some((sym::align, literal)) => {
2967 let alignment = rustc_attr::parse_alignment(&literal.kind);
2970 Ok(align) => Some(align),
2973 tcx.sess.diagnostic(),
2976 "invalid `repr(align)` attribute: {}",
2995 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2996 if !attr.has_name(sym::inline) {
2999 match attr.meta().map(|i| i.kind) {
3000 Some(MetaItemKind::Word) => InlineAttr::Hint,
3001 Some(MetaItemKind::List(ref items)) => {
3002 inline_span = Some(attr.span);
3003 if items.len() != 1 {
3005 tcx.sess.diagnostic(),
3008 "expected one argument"
3012 } else if list_contains_name(&items, sym::always) {
3014 } else if list_contains_name(&items, sym::never) {
3018 tcx.sess.diagnostic(),
3028 Some(MetaItemKind::NameValue(_)) => ia,
3033 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3034 if !attr.has_name(sym::optimize) {
3037 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3038 match attr.meta().map(|i| i.kind) {
3039 Some(MetaItemKind::Word) => {
3040 err(attr.span, "expected one argument");
3043 Some(MetaItemKind::List(ref items)) => {
3044 inline_span = Some(attr.span);
3045 if items.len() != 1 {
3046 err(attr.span, "expected one argument");
3048 } else if list_contains_name(&items, sym::size) {
3050 } else if list_contains_name(&items, sym::speed) {
3053 err(items[0].span(), "invalid argument");
3057 Some(MetaItemKind::NameValue(_)) => ia,
3062 // #73631: closures inherit `#[target_feature]` annotations
3063 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3064 let owner_id = tcx.parent(id).expect("closure should have a parent");
3067 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3070 // If a function uses #[target_feature] it can't be inlined into general
3071 // purpose functions as they wouldn't have the right target features
3072 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3074 if !codegen_fn_attrs.target_features.is_empty() {
3075 if codegen_fn_attrs.inline == InlineAttr::Always {
3076 if let Some(span) = inline_span {
3079 "cannot use `#[inline(always)]` with \
3080 `#[target_feature]`",
3086 if !codegen_fn_attrs.no_sanitize.is_empty() {
3087 if codegen_fn_attrs.inline == InlineAttr::Always {
3088 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3089 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3090 tcx.struct_span_lint_hir(
3091 lint::builtin::INLINE_NO_SANITIZE,
3095 lint.build("`no_sanitize` will have no effect after inlining")
3096 .span_note(inline_span, "inlining requested here")
3104 // Weak lang items have the same semantics as "std internal" symbols in the
3105 // sense that they're preserved through all our LTO passes and only
3106 // strippable by the linker.
3108 // Additionally weak lang items have predetermined symbol names.
3109 if tcx.is_weak_lang_item(id) {
3110 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3112 let check_name = |attr: &Attribute, sym| attr.has_name(sym);
3113 if let Some(name) = weak_lang_items::link_name(check_name, attrs) {
3114 codegen_fn_attrs.export_name = Some(name);
3115 codegen_fn_attrs.link_name = Some(name);
3117 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3119 // Internal symbols to the standard library all have no_mangle semantics in
3120 // that they have defined symbol names present in the function name. This
3121 // also applies to weak symbols where they all have known symbol names.
3122 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3123 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3126 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3127 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3128 // intrinsic functions.
3129 if let Some(name) = &codegen_fn_attrs.link_name {
3130 if name.as_str().starts_with("llvm.") {
3131 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3138 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3139 /// applied to the method prototype.
3140 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3141 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
3142 if let ty::AssocItemContainer::ImplContainer(impl_def_id) = impl_item.container {
3143 if let Some(trait_def_id) = tcx.trait_id_of_impl(impl_def_id) {
3144 if let Some(trait_item) = tcx
3145 .associated_items(trait_def_id)
3146 .filter_by_name_unhygienic(impl_item.ident.name)
3147 .find(move |trait_item| {
3148 trait_item.kind == ty::AssocKind::Fn
3149 && tcx.hygienic_eq(impl_item.ident, trait_item.ident, trait_def_id)
3153 .codegen_fn_attrs(trait_item.def_id)
3155 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3164 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3165 use rustc_ast::{Lit, LitIntType, LitKind};
3166 let meta_item_list = attr.meta_item_list();
3167 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3168 let sole_meta_list = match meta_item_list {
3169 Some([item]) => item.literal(),
3172 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3173 .note("the attribute requires exactly one argument")
3179 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3180 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3181 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3182 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3183 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3185 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3186 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3187 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3188 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3189 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3190 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3191 // about LINK.EXE failing.)
3192 if *ordinal <= u16::MAX as u128 {
3193 Some(*ordinal as u16)
3195 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3197 .struct_span_err(attr.span, &msg)
3198 .note("the value may not exceed `u16::MAX`")
3204 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3205 .note("an unsuffixed integer value, e.g., `1`, is expected")
3211 fn check_link_name_xor_ordinal(
3213 codegen_fn_attrs: &CodegenFnAttrs,
3214 inline_span: Option<Span>,
3216 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3219 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3220 if let Some(span) = inline_span {
3221 tcx.sess.span_err(span, msg);
3227 /// Checks the function annotated with `#[target_feature]` is not a safe
3228 /// trait method implementation, reporting an error if it is.
3229 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3230 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3231 let node = tcx.hir().get(hir_id);
3232 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3233 let parent_id = tcx.hir().get_parent_did(hir_id);
3234 let parent_item = tcx.hir().expect_item(parent_id);
3235 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3239 "`#[target_feature(..)]` cannot be applied to safe trait method",
3241 .span_label(attr_span, "cannot be applied to safe trait method")
3242 .span_label(tcx.def_span(id), "not an `unsafe` function")