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, Res};
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, 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();
181 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
182 last.bounds_span().unwrap_or(last.span).shrink_to_hi(),
183 format!(", {}", type_name),
187 let mut err = bad_placeholder_type(tcx, placeholder_types, kind);
189 // Suggest, but only if it is not a function in const or static
191 let mut is_fn = false;
192 let mut is_const_or_static = false;
194 if let Some(hir_ty) = hir_ty {
195 if let hir::TyKind::BareFn(_) = hir_ty.kind {
198 // Check if parent is const or static
199 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
200 let parent_node = tcx.hir().get(parent_id);
202 is_const_or_static = matches!(
204 Node::Item(&hir::Item {
205 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
207 }) | Node::TraitItem(&hir::TraitItem {
208 kind: hir::TraitItemKind::Const(..),
210 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
215 // if function is wrapped around a const or static,
216 // then don't show the suggestion
217 if !(is_fn && is_const_or_static) {
218 err.multipart_suggestion(
219 "use type parameters instead",
221 Applicability::HasPlaceholders,
228 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
229 let (generics, suggest) = match &item.kind {
230 hir::ItemKind::Union(_, generics)
231 | hir::ItemKind::Enum(_, generics)
232 | hir::ItemKind::TraitAlias(generics, _)
233 | hir::ItemKind::Trait(_, _, generics, ..)
234 | hir::ItemKind::Impl(hir::Impl { generics, .. })
235 | hir::ItemKind::Struct(_, generics) => (generics, true),
236 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
237 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
238 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
242 let mut visitor = PlaceholderHirTyCollector::default();
243 visitor.visit_item(item);
245 placeholder_type_error(
256 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
257 type Map = Map<'tcx>;
259 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
260 NestedVisitorMap::OnlyBodies(self.tcx.hir())
263 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
264 convert_item(self.tcx, item.item_id());
265 reject_placeholder_type_signatures_in_item(self.tcx, item);
266 intravisit::walk_item(self, item);
269 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
270 for param in generics.params {
272 hir::GenericParamKind::Lifetime { .. } => {}
273 hir::GenericParamKind::Type { default: Some(_), .. } => {
274 let def_id = self.tcx.hir().local_def_id(param.hir_id);
275 self.tcx.ensure().type_of(def_id);
277 hir::GenericParamKind::Type { .. } => {}
278 hir::GenericParamKind::Const { default, .. } => {
279 let def_id = self.tcx.hir().local_def_id(param.hir_id);
280 self.tcx.ensure().type_of(def_id);
281 if let Some(default) = default {
282 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
283 // need to store default and type of default
284 self.tcx.ensure().type_of(default_def_id);
285 self.tcx.ensure().const_param_default(def_id);
290 intravisit::walk_generics(self, generics);
293 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
294 if let hir::ExprKind::Closure(..) = expr.kind {
295 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
296 self.tcx.ensure().generics_of(def_id);
297 self.tcx.ensure().type_of(def_id);
299 intravisit::walk_expr(self, expr);
302 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
303 convert_trait_item(self.tcx, trait_item.trait_item_id());
304 intravisit::walk_trait_item(self, trait_item);
307 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
308 convert_impl_item(self.tcx, impl_item.impl_item_id());
309 intravisit::walk_impl_item(self, impl_item);
313 ///////////////////////////////////////////////////////////////////////////
314 // Utility types and common code for the above passes.
316 fn bad_placeholder_type(
318 mut spans: Vec<Span>,
320 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
321 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
324 let mut err = struct_span_err!(
328 "the type placeholder `_` is not allowed within types on item signatures for {}",
332 err.span_label(span, "not allowed in type signatures");
337 impl ItemCtxt<'tcx> {
338 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
339 ItemCtxt { tcx, item_def_id }
342 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
343 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
346 pub fn hir_id(&self) -> hir::HirId {
347 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
350 pub fn node(&self) -> hir::Node<'tcx> {
351 self.tcx.hir().get(self.hir_id())
355 impl AstConv<'tcx> for ItemCtxt<'tcx> {
356 fn tcx(&self) -> TyCtxt<'tcx> {
360 fn item_def_id(&self) -> Option<DefId> {
361 Some(self.item_def_id)
364 fn get_type_parameter_bounds(
369 ) -> ty::GenericPredicates<'tcx> {
370 self.tcx.at(span).type_param_predicates((
372 def_id.expect_local(),
377 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
381 fn allow_ty_infer(&self) -> bool {
385 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
386 self.tcx().ty_error_with_message(span, "bad_placeholder_type")
392 _: Option<&ty::GenericParamDef>,
394 ) -> &'tcx Const<'tcx> {
395 bad_placeholder_type(self.tcx(), vec![span], "generic").emit();
396 // Typeck doesn't expect erased regions to be returned from `type_of`.
397 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match r {
398 ty::ReErased => self.tcx.lifetimes.re_static,
401 self.tcx().const_error(ty)
404 fn projected_ty_from_poly_trait_ref(
408 item_segment: &hir::PathSegment<'_>,
409 poly_trait_ref: ty::PolyTraitRef<'tcx>,
411 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
412 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
420 self.tcx().mk_projection(item_def_id, item_substs)
422 // There are no late-bound regions; we can just ignore the binder.
423 let mut err = struct_span_err!(
427 "cannot use the associated type of a trait \
428 with uninferred generic parameters"
432 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
434 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
436 hir::ItemKind::Enum(_, generics)
437 | hir::ItemKind::Struct(_, generics)
438 | hir::ItemKind::Union(_, generics) => {
439 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
440 let (lt_sp, sugg) = match generics.params {
441 [] => (generics.span, format!("<{}>", lt_name)),
443 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
446 let suggestions = vec![
449 span.with_hi(item_segment.ident.span.lo()),
452 // Replace the existing lifetimes with a new named lifetime.
454 .replace_late_bound_regions(poly_trait_ref, |_| {
455 self.tcx.mk_region(ty::ReEarlyBound(
456 ty::EarlyBoundRegion {
459 name: Symbol::intern(<_name),
467 err.multipart_suggestion(
468 "use a fully qualified path with explicit lifetimes",
470 Applicability::MaybeIncorrect,
476 hir::Node::Item(hir::Item {
478 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
482 | hir::Node::ForeignItem(_)
483 | hir::Node::TraitItem(_)
484 | hir::Node::ImplItem(_) => {
485 err.span_suggestion_verbose(
486 span.with_hi(item_segment.ident.span.lo()),
487 "use a fully qualified path with inferred lifetimes",
490 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
491 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
493 Applicability::MaybeIncorrect,
499 self.tcx().ty_error()
503 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
504 // Types in item signatures are not normalized to avoid undue dependencies.
508 fn set_tainted_by_errors(&self) {
509 // There's no obvious place to track this, so just let it go.
512 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
513 // There's no place to record types from signatures?
517 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
518 fn get_new_lifetime_name<'tcx>(
520 poly_trait_ref: ty::PolyTraitRef<'tcx>,
521 generics: &hir::Generics<'tcx>,
523 let existing_lifetimes = tcx
524 .collect_referenced_late_bound_regions(&poly_trait_ref)
527 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
528 Some(name.as_str().to_string())
533 .chain(generics.params.iter().filter_map(|param| {
534 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
535 Some(param.name.ident().as_str().to_string())
540 .collect::<FxHashSet<String>>();
542 let a_to_z_repeat_n = |n| {
543 (b'a'..=b'z').map(move |c| {
544 let mut s = '\''.to_string();
545 s.extend(std::iter::repeat(char::from(c)).take(n));
550 // If all single char lifetime names are present, we wrap around and double the chars.
551 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
554 /// Returns the predicates defined on `item_def_id` of the form
555 /// `X: Foo` where `X` is the type parameter `def_id`.
556 fn type_param_predicates(
558 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
559 ) -> ty::GenericPredicates<'_> {
562 // In the AST, bounds can derive from two places. Either
563 // written inline like `<T: Foo>` or in a where-clause like
566 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
567 let param_owner = tcx.hir().ty_param_owner(param_id);
568 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
569 let generics = tcx.generics_of(param_owner_def_id);
570 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
571 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
573 // Don't look for bounds where the type parameter isn't in scope.
574 let parent = if item_def_id == param_owner_def_id.to_def_id() {
577 tcx.generics_of(item_def_id).parent
580 let mut result = parent
582 let icx = ItemCtxt::new(tcx, parent);
583 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
585 .unwrap_or_default();
586 let mut extend = None;
588 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
589 let ast_generics = match tcx.hir().get(item_hir_id) {
590 Node::TraitItem(item) => &item.generics,
592 Node::ImplItem(item) => &item.generics,
594 Node::Item(item) => {
596 ItemKind::Fn(.., ref generics, _)
597 | ItemKind::Impl(hir::Impl { ref generics, .. })
598 | ItemKind::TyAlias(_, ref generics)
599 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
600 | ItemKind::Enum(_, ref generics)
601 | ItemKind::Struct(_, ref generics)
602 | ItemKind::Union(_, ref generics) => generics,
603 ItemKind::Trait(_, _, ref generics, ..) => {
604 // Implied `Self: Trait` and supertrait bounds.
605 if param_id == item_hir_id {
606 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
608 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
616 Node::ForeignItem(item) => match item.kind {
617 ForeignItemKind::Fn(_, _, ref generics) => generics,
624 let icx = ItemCtxt::new(tcx, item_def_id);
625 let extra_predicates = extend.into_iter().chain(
626 icx.type_parameter_bounds_in_generics(
630 OnlySelfBounds(true),
634 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
635 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
640 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
644 impl ItemCtxt<'tcx> {
645 /// Finds bounds from `hir::Generics`. This requires scanning through the
646 /// AST. We do this to avoid having to convert *all* the bounds, which
647 /// would create artificial cycles. Instead, we can only convert the
648 /// bounds for a type parameter `X` if `X::Foo` is used.
649 fn type_parameter_bounds_in_generics(
651 ast_generics: &'tcx hir::Generics<'tcx>,
652 param_id: hir::HirId,
654 only_self_bounds: OnlySelfBounds,
655 assoc_name: Option<Ident>,
656 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
657 let from_ty_params = ast_generics
660 .filter_map(|param| match param.kind {
661 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
664 .flat_map(|bounds| bounds.iter())
665 .filter(|b| match assoc_name {
666 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
669 .flat_map(|b| predicates_from_bound(self, ty, b));
671 let from_where_clauses = ast_generics
675 .filter_map(|wp| match *wp {
676 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
680 let bt = if is_param(self.tcx, bp.bounded_ty, param_id) {
682 } else if !only_self_bounds.0 {
683 Some(self.to_ty(bp.bounded_ty))
689 .filter(|b| match assoc_name {
690 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
693 .filter_map(move |b| bt.map(|bt| (bt, b)))
695 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
697 from_ty_params.chain(from_where_clauses).collect()
700 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
701 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
704 hir::GenericBound::Trait(poly_trait_ref, _) => {
705 let trait_ref = &poly_trait_ref.trait_ref;
706 if let Some(trait_did) = trait_ref.trait_def_id() {
707 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
717 /// Tests whether this is the AST for a reference to the type
718 /// parameter with ID `param_id`. We use this so as to avoid running
719 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
720 /// conversion of the type to avoid inducing unnecessary cycles.
721 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
722 if let hir::TyKind::Path(hir::QPath::Resolved(None, path)) = ast_ty.kind {
724 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
725 def_id == tcx.hir().local_def_id(param_id).to_def_id()
734 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
735 let it = tcx.hir().item(item_id);
736 debug!("convert: item {} with id {}", it.ident, it.hir_id());
737 let def_id = item_id.def_id;
740 // These don't define types.
741 hir::ItemKind::ExternCrate(_)
742 | hir::ItemKind::Use(..)
743 | hir::ItemKind::Macro(_)
744 | hir::ItemKind::Mod(_)
745 | hir::ItemKind::GlobalAsm(_) => {}
746 hir::ItemKind::ForeignMod { items, .. } => {
748 let item = tcx.hir().foreign_item(item.id);
749 tcx.ensure().generics_of(item.def_id);
750 tcx.ensure().type_of(item.def_id);
751 tcx.ensure().predicates_of(item.def_id);
753 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
754 hir::ForeignItemKind::Static(..) => {
755 let mut visitor = PlaceholderHirTyCollector::default();
756 visitor.visit_foreign_item(item);
757 placeholder_type_error(
771 hir::ItemKind::Enum(ref enum_definition, _) => {
772 tcx.ensure().generics_of(def_id);
773 tcx.ensure().type_of(def_id);
774 tcx.ensure().predicates_of(def_id);
775 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
777 hir::ItemKind::Impl { .. } => {
778 tcx.ensure().generics_of(def_id);
779 tcx.ensure().type_of(def_id);
780 tcx.ensure().impl_trait_ref(def_id);
781 tcx.ensure().predicates_of(def_id);
783 hir::ItemKind::Trait(..) => {
784 tcx.ensure().generics_of(def_id);
785 tcx.ensure().trait_def(def_id);
786 tcx.at(it.span).super_predicates_of(def_id);
787 tcx.ensure().predicates_of(def_id);
789 hir::ItemKind::TraitAlias(..) => {
790 tcx.ensure().generics_of(def_id);
791 tcx.at(it.span).super_predicates_of(def_id);
792 tcx.ensure().predicates_of(def_id);
794 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
795 tcx.ensure().generics_of(def_id);
796 tcx.ensure().type_of(def_id);
797 tcx.ensure().predicates_of(def_id);
799 for f in struct_def.fields() {
800 let def_id = tcx.hir().local_def_id(f.hir_id);
801 tcx.ensure().generics_of(def_id);
802 tcx.ensure().type_of(def_id);
803 tcx.ensure().predicates_of(def_id);
806 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
807 convert_variant_ctor(tcx, ctor_hir_id);
811 // Desugared from `impl Trait`, so visited by the function's return type.
812 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
814 // Don't call `type_of` on opaque types, since that depends on type
815 // checking function bodies. `check_item_type` ensures that it's called
817 hir::ItemKind::OpaqueTy(..) => {
818 tcx.ensure().generics_of(def_id);
819 tcx.ensure().predicates_of(def_id);
820 tcx.ensure().explicit_item_bounds(def_id);
822 hir::ItemKind::TyAlias(..)
823 | hir::ItemKind::Static(..)
824 | hir::ItemKind::Const(..)
825 | hir::ItemKind::Fn(..) => {
826 tcx.ensure().generics_of(def_id);
827 tcx.ensure().type_of(def_id);
828 tcx.ensure().predicates_of(def_id);
830 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
831 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
832 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
833 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
834 if let hir::TyKind::TraitObject(..) = ty.kind {
835 let mut visitor = PlaceholderHirTyCollector::default();
836 visitor.visit_item(it);
837 placeholder_type_error(
854 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
855 let trait_item = tcx.hir().trait_item(trait_item_id);
856 tcx.ensure().generics_of(trait_item_id.def_id);
858 match trait_item.kind {
859 hir::TraitItemKind::Fn(..) => {
860 tcx.ensure().type_of(trait_item_id.def_id);
861 tcx.ensure().fn_sig(trait_item_id.def_id);
864 hir::TraitItemKind::Const(.., Some(_)) => {
865 tcx.ensure().type_of(trait_item_id.def_id);
868 hir::TraitItemKind::Const(..) => {
869 tcx.ensure().type_of(trait_item_id.def_id);
870 // Account for `const C: _;`.
871 let mut visitor = PlaceholderHirTyCollector::default();
872 visitor.visit_trait_item(trait_item);
873 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
876 hir::TraitItemKind::Type(_, Some(_)) => {
877 tcx.ensure().item_bounds(trait_item_id.def_id);
878 tcx.ensure().type_of(trait_item_id.def_id);
879 // Account for `type T = _;`.
880 let mut visitor = PlaceholderHirTyCollector::default();
881 visitor.visit_trait_item(trait_item);
882 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
885 hir::TraitItemKind::Type(_, None) => {
886 tcx.ensure().item_bounds(trait_item_id.def_id);
887 // #74612: Visit and try to find bad placeholders
888 // even if there is no concrete type.
889 let mut visitor = PlaceholderHirTyCollector::default();
890 visitor.visit_trait_item(trait_item);
892 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
896 tcx.ensure().predicates_of(trait_item_id.def_id);
899 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
900 let def_id = impl_item_id.def_id;
901 tcx.ensure().generics_of(def_id);
902 tcx.ensure().type_of(def_id);
903 tcx.ensure().predicates_of(def_id);
904 let impl_item = tcx.hir().impl_item(impl_item_id);
905 match impl_item.kind {
906 hir::ImplItemKind::Fn(..) => {
907 tcx.ensure().fn_sig(def_id);
909 hir::ImplItemKind::TyAlias(_) => {
910 // Account for `type T = _;`
911 let mut visitor = PlaceholderHirTyCollector::default();
912 visitor.visit_impl_item(impl_item);
914 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
916 hir::ImplItemKind::Const(..) => {}
920 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
921 let def_id = tcx.hir().local_def_id(ctor_id);
922 tcx.ensure().generics_of(def_id);
923 tcx.ensure().type_of(def_id);
924 tcx.ensure().predicates_of(def_id);
927 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
928 let def = tcx.adt_def(def_id);
929 let repr_type = def.repr.discr_type();
930 let initial = repr_type.initial_discriminant(tcx);
931 let mut prev_discr = None::<Discr<'_>>;
933 // fill the discriminant values and field types
934 for variant in variants {
935 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
937 if let Some(ref e) = variant.disr_expr {
938 let expr_did = tcx.hir().local_def_id(e.hir_id);
939 def.eval_explicit_discr(tcx, expr_did.to_def_id())
940 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
943 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
946 format!("overflowed on value after {}", prev_discr.unwrap()),
949 "explicitly set `{} = {}` if that is desired outcome",
950 variant.ident, wrapped_discr
955 .unwrap_or(wrapped_discr),
958 for f in variant.data.fields() {
959 let def_id = tcx.hir().local_def_id(f.hir_id);
960 tcx.ensure().generics_of(def_id);
961 tcx.ensure().type_of(def_id);
962 tcx.ensure().predicates_of(def_id);
965 // Convert the ctor, if any. This also registers the variant as
967 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
968 convert_variant_ctor(tcx, ctor_hir_id);
975 variant_did: Option<LocalDefId>,
976 ctor_did: Option<LocalDefId>,
978 discr: ty::VariantDiscr,
979 def: &hir::VariantData<'_>,
980 adt_kind: ty::AdtKind,
981 parent_did: LocalDefId,
982 ) -> ty::VariantDef {
983 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
988 let fid = tcx.hir().local_def_id(f.hir_id);
989 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
990 if let Some(prev_span) = dup_span {
991 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
997 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
1000 ty::FieldDef { did: fid.to_def_id(), ident: f.ident, vis: tcx.visibility(fid) }
1003 let recovered = match def {
1004 hir::VariantData::Struct(_, r) => *r,
1007 ty::VariantDef::new(
1009 variant_did.map(LocalDefId::to_def_id),
1010 ctor_did.map(LocalDefId::to_def_id),
1013 CtorKind::from_hir(def),
1015 parent_did.to_def_id(),
1017 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1018 || variant_did.map_or(false, |variant_did| {
1019 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1024 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
1027 let def_id = def_id.expect_local();
1028 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1029 let item = match tcx.hir().get(hir_id) {
1030 Node::Item(item) => item,
1034 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1035 let (kind, variants) = match item.kind {
1036 ItemKind::Enum(ref def, _) => {
1037 let mut distance_from_explicit = 0;
1042 let variant_did = Some(tcx.hir().local_def_id(v.id));
1044 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1046 let discr = if let Some(ref e) = v.disr_expr {
1047 distance_from_explicit = 0;
1048 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1050 ty::VariantDiscr::Relative(distance_from_explicit)
1052 distance_from_explicit += 1;
1067 (AdtKind::Enum, variants)
1069 ItemKind::Struct(ref def, _) => {
1070 let variant_did = None::<LocalDefId>;
1071 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1073 let variants = std::iter::once(convert_variant(
1078 ty::VariantDiscr::Relative(0),
1085 (AdtKind::Struct, variants)
1087 ItemKind::Union(ref def, _) => {
1088 let variant_did = None;
1089 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1091 let variants = std::iter::once(convert_variant(
1096 ty::VariantDiscr::Relative(0),
1103 (AdtKind::Union, variants)
1107 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1110 /// Ensures that the super-predicates of the trait with a `DefId`
1111 /// of `trait_def_id` are converted and stored. This also ensures that
1112 /// the transitive super-predicates are converted.
1113 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1114 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1115 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1118 /// Ensures that the super-predicates of the trait with a `DefId`
1119 /// of `trait_def_id` are converted and stored. This also ensures that
1120 /// the transitive super-predicates are converted.
1121 fn super_predicates_that_define_assoc_type(
1123 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1124 ) -> ty::GenericPredicates<'_> {
1126 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1127 trait_def_id, assoc_name
1129 if trait_def_id.is_local() {
1130 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1131 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1133 let item = match tcx.hir().get(trait_hir_id) {
1134 Node::Item(item) => item,
1135 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
1138 let (generics, bounds) = match item.kind {
1139 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1140 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1141 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1144 let icx = ItemCtxt::new(tcx, trait_def_id);
1146 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1147 let self_param_ty = tcx.types.self_param;
1148 let superbounds1 = if let Some(assoc_name) = assoc_name {
1149 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1156 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1159 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1161 // Convert any explicit superbounds in the where-clause,
1162 // e.g., `trait Foo where Self: Bar`.
1163 // In the case of trait aliases, however, we include all bounds in the where-clause,
1164 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1165 // as one of its "superpredicates".
1166 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1167 let superbounds2 = icx.type_parameter_bounds_in_generics(
1171 OnlySelfBounds(!is_trait_alias),
1175 // Combine the two lists to form the complete set of superbounds:
1176 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1178 // Now require that immediate supertraits are converted,
1179 // which will, in turn, reach indirect supertraits.
1180 if assoc_name.is_none() {
1181 // Now require that immediate supertraits are converted,
1182 // which will, in turn, reach indirect supertraits.
1183 for &(pred, span) in superbounds {
1184 debug!("superbound: {:?}", pred);
1185 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1186 tcx.at(span).super_predicates_of(bound.def_id());
1191 ty::GenericPredicates { parent: None, predicates: superbounds }
1193 // if `assoc_name` is None, then the query should've been redirected to an
1194 // external provider
1195 assert!(assoc_name.is_some());
1196 tcx.super_predicates_of(trait_def_id)
1200 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1201 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1202 let item = tcx.hir().expect_item(hir_id);
1204 let (is_auto, unsafety) = match item.kind {
1205 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
1206 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
1207 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1210 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1211 if paren_sugar && !tcx.features().unboxed_closures {
1215 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1216 which traits can use parenthetical notation",
1218 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1222 let is_marker = tcx.has_attr(def_id, sym::marker);
1223 let skip_array_during_method_dispatch =
1224 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1225 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1226 ty::trait_def::TraitSpecializationKind::Marker
1227 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1228 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1230 ty::trait_def::TraitSpecializationKind::None
1232 let def_path_hash = tcx.def_path_hash(def_id);
1239 skip_array_during_method_dispatch,
1245 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1246 struct LateBoundRegionsDetector<'tcx> {
1248 outer_index: ty::DebruijnIndex,
1249 has_late_bound_regions: Option<Span>,
1252 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1253 type Map = intravisit::ErasedMap<'tcx>;
1255 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1256 NestedVisitorMap::None
1259 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1260 if self.has_late_bound_regions.is_some() {
1264 hir::TyKind::BareFn(..) => {
1265 self.outer_index.shift_in(1);
1266 intravisit::walk_ty(self, ty);
1267 self.outer_index.shift_out(1);
1269 _ => intravisit::walk_ty(self, ty),
1273 fn visit_poly_trait_ref(
1275 tr: &'tcx hir::PolyTraitRef<'tcx>,
1276 m: hir::TraitBoundModifier,
1278 if self.has_late_bound_regions.is_some() {
1281 self.outer_index.shift_in(1);
1282 intravisit::walk_poly_trait_ref(self, tr, m);
1283 self.outer_index.shift_out(1);
1286 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1287 if self.has_late_bound_regions.is_some() {
1291 match self.tcx.named_region(lt.hir_id) {
1292 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1294 rl::Region::LateBound(debruijn, _, _, _)
1295 | rl::Region::LateBoundAnon(debruijn, _, _),
1296 ) if debruijn < self.outer_index => {}
1298 rl::Region::LateBound(..)
1299 | rl::Region::LateBoundAnon(..)
1300 | rl::Region::Free(..),
1303 self.has_late_bound_regions = Some(lt.span);
1309 fn has_late_bound_regions<'tcx>(
1311 generics: &'tcx hir::Generics<'tcx>,
1312 decl: &'tcx hir::FnDecl<'tcx>,
1314 let mut visitor = LateBoundRegionsDetector {
1316 outer_index: ty::INNERMOST,
1317 has_late_bound_regions: None,
1319 for param in generics.params {
1320 if let GenericParamKind::Lifetime { .. } = param.kind {
1321 if tcx.is_late_bound(param.hir_id) {
1322 return Some(param.span);
1326 visitor.visit_fn_decl(decl);
1327 visitor.has_late_bound_regions
1331 Node::TraitItem(item) => match item.kind {
1332 hir::TraitItemKind::Fn(ref sig, _) => {
1333 has_late_bound_regions(tcx, &item.generics, sig.decl)
1337 Node::ImplItem(item) => match item.kind {
1338 hir::ImplItemKind::Fn(ref sig, _) => {
1339 has_late_bound_regions(tcx, &item.generics, sig.decl)
1343 Node::ForeignItem(item) => match item.kind {
1344 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1345 has_late_bound_regions(tcx, generics, fn_decl)
1349 Node::Item(item) => match item.kind {
1350 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1351 has_late_bound_regions(tcx, generics, sig.decl)
1359 struct AnonConstInParamTyDetector {
1361 found_anon_const_in_param_ty: bool,
1365 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1366 type Map = intravisit::ErasedMap<'v>;
1368 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1369 NestedVisitorMap::None
1372 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1373 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1374 let prev = self.in_param_ty;
1375 self.in_param_ty = true;
1377 self.in_param_ty = prev;
1381 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1382 if self.in_param_ty && self.ct == c.hir_id {
1383 self.found_anon_const_in_param_ty = true;
1385 intravisit::walk_anon_const(self, c)
1390 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1393 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1395 let node = tcx.hir().get(hir_id);
1396 let parent_def_id = match node {
1398 | Node::TraitItem(_)
1401 | Node::Field(_) => {
1402 let parent_id = tcx.hir().get_parent_item(hir_id);
1403 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1405 // FIXME(#43408) always enable this once `lazy_normalization` is
1406 // stable enough and does not need a feature gate anymore.
1407 Node::AnonConst(_) => {
1408 let parent_id = tcx.hir().get_parent_item(hir_id);
1409 let parent_def_id = tcx.hir().local_def_id(parent_id);
1411 let mut in_param_ty = false;
1412 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1413 if let Some(generics) = node.generics() {
1414 let mut visitor = AnonConstInParamTyDetector {
1416 found_anon_const_in_param_ty: false,
1420 visitor.visit_generics(generics);
1421 in_param_ty = visitor.found_anon_const_in_param_ty;
1427 // We do not allow generic parameters in anon consts if we are inside
1428 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1430 } else if tcx.lazy_normalization() {
1431 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1432 // If the def_id we are calling generics_of on is an anon ct default i.e:
1434 // struct Foo<const N: usize = { .. }>;
1435 // ^^^ ^ ^^^^^^ def id of this anon const
1439 // then we only want to return generics for params to the left of `N`. If we don't do that we
1440 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1442 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1443 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1444 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1446 // We fix this by having this function return the parent's generics ourselves and truncating the
1447 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1449 // For the above code example that means we want `substs: []`
1450 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1451 // the def id of the `{ N + 1 }` anon const
1452 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1454 // This has some implications for how we get the predicates available to the anon const
1455 // see `explicit_predicates_of` for more information on this
1456 let generics = tcx.generics_of(parent_def_id.to_def_id());
1457 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1458 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1459 // In the above example this would be .params[..N#0]
1460 let params = generics.params[..param_def_idx as usize].to_owned();
1461 let param_def_id_to_index =
1462 params.iter().map(|param| (param.def_id, param.index)).collect();
1464 return ty::Generics {
1465 // we set the parent of these generics to be our parent's parent so that we
1466 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1467 // struct Foo<const N: usize, const M: usize = { ... }>;
1468 parent: generics.parent,
1469 parent_count: generics.parent_count,
1471 param_def_id_to_index,
1472 has_self: generics.has_self,
1473 has_late_bound_regions: generics.has_late_bound_regions,
1477 // HACK(eddyb) this provides the correct generics when
1478 // `feature(generic_const_expressions)` is enabled, so that const expressions
1479 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1481 // Note that we do not supply the parent generics when using
1482 // `min_const_generics`.
1483 Some(parent_def_id.to_def_id())
1485 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1487 // HACK(eddyb) this provides the correct generics for repeat
1488 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1489 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1490 // as they shouldn't be able to cause query cycle errors.
1491 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1492 | Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1493 if constant.hir_id == hir_id =>
1495 Some(parent_def_id.to_def_id())
1497 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1498 Some(tcx.typeck_root_def_id(def_id))
1504 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1505 Some(tcx.typeck_root_def_id(def_id))
1507 Node::Item(item) => match item.kind {
1508 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => {
1509 impl_trait_fn.or_else(|| {
1510 let parent_id = tcx.hir().get_parent_item(hir_id);
1511 assert!(parent_id != hir_id && parent_id != CRATE_HIR_ID);
1512 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1513 // Opaque types are always nested within another item, and
1514 // inherit the generics of the item.
1515 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1523 let mut opt_self = None;
1524 let mut allow_defaults = false;
1526 let no_generics = hir::Generics::empty();
1527 let ast_generics = match node {
1528 Node::TraitItem(item) => &item.generics,
1530 Node::ImplItem(item) => &item.generics,
1532 Node::Item(item) => {
1534 ItemKind::Fn(.., ref generics, _)
1535 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1537 ItemKind::TyAlias(_, ref generics)
1538 | ItemKind::Enum(_, ref generics)
1539 | ItemKind::Struct(_, ref generics)
1540 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1541 | ItemKind::Union(_, ref generics) => {
1542 allow_defaults = true;
1546 ItemKind::Trait(_, _, ref generics, ..)
1547 | ItemKind::TraitAlias(ref generics, ..) => {
1548 // Add in the self type parameter.
1550 // Something of a hack: use the node id for the trait, also as
1551 // the node id for the Self type parameter.
1552 let param_id = item.def_id;
1554 opt_self = Some(ty::GenericParamDef {
1556 name: kw::SelfUpper,
1557 def_id: param_id.to_def_id(),
1558 pure_wrt_drop: false,
1559 kind: ty::GenericParamDefKind::Type {
1561 object_lifetime_default: rl::Set1::Empty,
1566 allow_defaults = true;
1574 Node::ForeignItem(item) => match item.kind {
1575 ForeignItemKind::Static(..) => &no_generics,
1576 ForeignItemKind::Fn(_, _, ref generics) => generics,
1577 ForeignItemKind::Type => &no_generics,
1583 let has_self = opt_self.is_some();
1584 let mut parent_has_self = false;
1585 let mut own_start = has_self as u32;
1586 let parent_count = parent_def_id.map_or(0, |def_id| {
1587 let generics = tcx.generics_of(def_id);
1589 parent_has_self = generics.has_self;
1590 own_start = generics.count() as u32;
1591 generics.parent_count + generics.params.len()
1594 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1596 if let Some(opt_self) = opt_self {
1597 params.push(opt_self);
1600 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1601 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1602 name: param.name.ident().name,
1603 index: own_start + i as u32,
1604 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1605 pure_wrt_drop: param.pure_wrt_drop,
1606 kind: ty::GenericParamDefKind::Lifetime,
1609 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1611 // Now create the real type and const parameters.
1612 let type_start = own_start - has_self as u32 + params.len() as u32;
1615 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1616 GenericParamKind::Lifetime { .. } => None,
1617 GenericParamKind::Type { ref default, synthetic, .. } => {
1618 if !allow_defaults && default.is_some() {
1619 if !tcx.features().default_type_parameter_fallback {
1620 tcx.struct_span_lint_hir(
1621 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1626 "defaults for type parameters are only allowed in \
1627 `struct`, `enum`, `type`, or `trait` definitions",
1635 let kind = ty::GenericParamDefKind::Type {
1636 has_default: default.is_some(),
1637 object_lifetime_default: object_lifetime_defaults
1639 .map_or(rl::Set1::Empty, |o| o[i]),
1643 let param_def = ty::GenericParamDef {
1644 index: type_start + i as u32,
1645 name: param.name.ident().name,
1646 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1647 pure_wrt_drop: param.pure_wrt_drop,
1653 GenericParamKind::Const { default, .. } => {
1654 if !allow_defaults && default.is_some() {
1657 "defaults for const parameters are only allowed in \
1658 `struct`, `enum`, `type`, or `trait` definitions",
1662 let param_def = ty::GenericParamDef {
1663 index: type_start + i as u32,
1664 name: param.name.ident().name,
1665 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1666 pure_wrt_drop: param.pure_wrt_drop,
1667 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1674 // provide junk type parameter defs - the only place that
1675 // cares about anything but the length is instantiation,
1676 // and we don't do that for closures.
1677 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1678 let dummy_args = if gen.is_some() {
1679 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1681 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1684 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1685 index: type_start + i as u32,
1686 name: Symbol::intern(arg),
1688 pure_wrt_drop: false,
1689 kind: ty::GenericParamDefKind::Type {
1691 object_lifetime_default: rl::Set1::Empty,
1697 // provide junk type parameter defs for const blocks.
1698 if let Node::AnonConst(_) = node {
1699 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1700 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1701 params.push(ty::GenericParamDef {
1703 name: Symbol::intern("<const_ty>"),
1705 pure_wrt_drop: false,
1706 kind: ty::GenericParamDefKind::Type {
1708 object_lifetime_default: rl::Set1::Empty,
1715 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1718 parent: parent_def_id,
1721 param_def_id_to_index,
1722 has_self: has_self || parent_has_self,
1723 has_late_bound_regions: has_late_bound_regions(tcx, node),
1727 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1728 generic_args.iter().any(|arg| match arg {
1729 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1730 hir::GenericArg::Infer(_) => true,
1735 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1736 /// use inference to provide suggestions for the appropriate type if possible.
1737 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1741 Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
1742 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1743 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1744 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1745 Path(hir::QPath::TypeRelative(ty, segment)) => {
1746 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1748 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1749 ty_opt.map_or(false, is_suggestable_infer_ty)
1750 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1756 pub fn get_infer_ret_ty(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1757 if let hir::FnRetTy::Return(ty) = output {
1758 if is_suggestable_infer_ty(ty) {
1765 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1766 use rustc_hir::Node::*;
1769 let def_id = def_id.expect_local();
1770 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1772 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1774 match tcx.hir().get(hir_id) {
1775 TraitItem(hir::TraitItem {
1776 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1781 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1782 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1783 match get_infer_ret_ty(&sig.decl.output) {
1785 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1786 // Typeck doesn't expect erased regions to be returned from `type_of`.
1787 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match r {
1788 ty::ReErased => tcx.lifetimes.re_static,
1791 let fn_sig = ty::Binder::dummy(fn_sig);
1793 let mut visitor = PlaceholderHirTyCollector::default();
1794 visitor.visit_ty(ty);
1795 let mut diag = bad_placeholder_type(tcx, visitor.0, "return type");
1796 let ret_ty = fn_sig.skip_binder().output();
1797 if ret_ty != tcx.ty_error() {
1798 if !ret_ty.is_closure() {
1799 let ret_ty_str = match ret_ty.kind() {
1800 // Suggest a function pointer return type instead of a unique function definition
1801 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1803 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1804 _ => ret_ty.to_string(),
1806 diag.span_suggestion(
1808 "replace with the correct return type",
1810 Applicability::MaybeIncorrect,
1813 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1814 // to prevent the user from getting a papercut while trying to use the unique closure
1815 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1816 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1817 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1824 None => <dyn AstConv<'_>>::ty_of_fn(
1827 sig.header.unsafety,
1837 TraitItem(hir::TraitItem {
1838 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1842 }) => <dyn AstConv<'_>>::ty_of_fn(
1853 ForeignItem(&hir::ForeignItem {
1854 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1856 let abi = tcx.hir().get_foreign_abi(hir_id);
1857 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1860 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1861 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id).to_def_id());
1863 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1864 ty::Binder::dummy(tcx.mk_fn_sig(
1868 hir::Unsafety::Normal,
1873 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1874 // Closure signatures are not like other function
1875 // signatures and cannot be accessed through `fn_sig`. For
1876 // example, a closure signature excludes the `self`
1877 // argument. In any case they are embedded within the
1878 // closure type as part of the `ClosureSubsts`.
1880 // To get the signature of a closure, you should use the
1881 // `sig` method on the `ClosureSubsts`:
1883 // substs.as_closure().sig(def_id, tcx)
1885 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1890 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1895 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1896 let icx = ItemCtxt::new(tcx, def_id);
1898 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1899 match tcx.hir().expect_item(hir_id).kind {
1900 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1901 let selfty = tcx.type_of(def_id);
1902 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1908 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1909 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1910 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1911 let item = tcx.hir().expect_item(hir_id);
1913 hir::ItemKind::Impl(hir::Impl {
1914 polarity: hir::ImplPolarity::Negative(span),
1918 if is_rustc_reservation {
1919 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
1920 tcx.sess.span_err(span, "reservation impls can't be negative");
1922 ty::ImplPolarity::Negative
1924 hir::ItemKind::Impl(hir::Impl {
1925 polarity: hir::ImplPolarity::Positive,
1929 if is_rustc_reservation {
1930 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1932 ty::ImplPolarity::Positive
1934 hir::ItemKind::Impl(hir::Impl {
1935 polarity: hir::ImplPolarity::Positive,
1939 if is_rustc_reservation {
1940 ty::ImplPolarity::Reservation
1942 ty::ImplPolarity::Positive
1945 item => bug!("impl_polarity: {:?} not an impl", item),
1949 /// Returns the early-bound lifetimes declared in this generics
1950 /// listing. For anything other than fns/methods, this is just all
1951 /// the lifetimes that are declared. For fns or methods, we have to
1952 /// screen out those that do not appear in any where-clauses etc using
1953 /// `resolve_lifetime::early_bound_lifetimes`.
1954 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1956 generics: &'a hir::Generics<'a>,
1957 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1958 generics.params.iter().filter(move |param| match param.kind {
1959 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1964 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1965 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1966 /// inferred constraints concerning which regions outlive other regions.
1967 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1968 debug!("predicates_defined_on({:?})", def_id);
1969 let mut result = tcx.explicit_predicates_of(def_id);
1970 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1971 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1972 if !inferred_outlives.is_empty() {
1974 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1975 def_id, inferred_outlives,
1977 if result.predicates.is_empty() {
1978 result.predicates = inferred_outlives;
1980 result.predicates = tcx
1982 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1986 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1990 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1991 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1992 /// `Self: Trait` predicates for traits.
1993 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1994 let mut result = tcx.predicates_defined_on(def_id);
1996 if tcx.is_trait(def_id) {
1997 // For traits, add `Self: Trait` predicate. This is
1998 // not part of the predicates that a user writes, but it
1999 // is something that one must prove in order to invoke a
2000 // method or project an associated type.
2002 // In the chalk setup, this predicate is not part of the
2003 // "predicates" for a trait item. But it is useful in
2004 // rustc because if you directly (e.g.) invoke a trait
2005 // method like `Trait::method(...)`, you must naturally
2006 // prove that the trait applies to the types that were
2007 // used, and adding the predicate into this list ensures
2008 // that this is done.
2009 let mut span = tcx.def_span(def_id);
2010 if tcx.sess.source_map().is_local_span(span) {
2011 // `guess_head_span` reads the actual source file from
2012 // disk to try to determine the 'head' snippet of the span.
2013 // Don't do this for a span that comes from a file outside
2014 // of our crate, since this would make our query output
2015 // (and overall crate metadata) dependent on the
2016 // *current* state of an external file.
2017 span = tcx.sess.source_map().guess_head_span(span);
2020 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2021 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2025 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2029 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2030 /// N.B., this does not include any implied/inferred constraints.
2031 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2034 debug!("explicit_predicates_of(def_id={:?})", def_id);
2036 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2037 let node = tcx.hir().get(hir_id);
2039 let mut is_trait = None;
2040 let mut is_default_impl_trait = None;
2042 let icx = ItemCtxt::new(tcx, def_id);
2044 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2046 // We use an `IndexSet` to preserves order of insertion.
2047 // Preserving the order of insertion is important here so as not to break UI tests.
2048 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2050 let ast_generics = match node {
2051 Node::TraitItem(item) => &item.generics,
2053 Node::ImplItem(item) => &item.generics,
2055 Node::Item(item) => {
2057 ItemKind::Impl(ref impl_) => {
2058 if impl_.defaultness.is_default() {
2059 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2063 ItemKind::Fn(.., ref generics, _)
2064 | ItemKind::TyAlias(_, ref generics)
2065 | ItemKind::Enum(_, ref generics)
2066 | ItemKind::Struct(_, ref generics)
2067 | ItemKind::Union(_, ref generics) => generics,
2069 ItemKind::Trait(_, _, ref generics, ..) => {
2070 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2073 ItemKind::TraitAlias(ref generics, _) => {
2074 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2077 ItemKind::OpaqueTy(OpaqueTy {
2083 if impl_trait_fn.is_some() {
2084 // return-position impl trait
2086 // We don't inherit predicates from the parent here:
2087 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2088 // then the return type is `f::<'static, T>::{{opaque}}`.
2090 // If we inherited the predicates of `f` then we would
2091 // require that `T: 'static` to show that the return
2092 // type is well-formed.
2094 // The only way to have something with this opaque type
2095 // is from the return type of the containing function,
2096 // which will ensure that the function's predicates
2098 return ty::GenericPredicates { parent: None, predicates: &[] };
2100 // type-alias impl trait
2109 Node::ForeignItem(item) => match item.kind {
2110 ForeignItemKind::Static(..) => NO_GENERICS,
2111 ForeignItemKind::Fn(_, _, ref generics) => generics,
2112 ForeignItemKind::Type => NO_GENERICS,
2118 let generics = tcx.generics_of(def_id);
2119 let parent_count = generics.parent_count as u32;
2120 let has_own_self = generics.has_self && parent_count == 0;
2122 // Below we'll consider the bounds on the type parameters (including `Self`)
2123 // and the explicit where-clauses, but to get the full set of predicates
2124 // on a trait we need to add in the supertrait bounds and bounds found on
2125 // associated types.
2126 if let Some(_trait_ref) = is_trait {
2127 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2130 // In default impls, we can assume that the self type implements
2131 // the trait. So in:
2133 // default impl Foo for Bar { .. }
2135 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2136 // (see below). Recall that a default impl is not itself an impl, but rather a
2137 // set of defaults that can be incorporated into another impl.
2138 if let Some(trait_ref) = is_default_impl_trait {
2139 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2142 // Collect the region predicates that were declared inline as
2143 // well. In the case of parameters declared on a fn or method, we
2144 // have to be careful to only iterate over early-bound regions.
2145 let mut index = parent_count + has_own_self as u32;
2146 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2147 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2148 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2150 name: param.name.ident().name,
2155 GenericParamKind::Lifetime { .. } => {
2156 param.bounds.iter().for_each(|bound| match bound {
2157 hir::GenericBound::Outlives(lt) => {
2158 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2159 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2160 predicates.insert((outlives.to_predicate(tcx), lt.span));
2169 // Collect the predicates that were written inline by the user on each
2170 // type parameter (e.g., `<T: Foo>`).
2171 for param in ast_generics.params {
2173 // We already dealt with early bound lifetimes above.
2174 GenericParamKind::Lifetime { .. } => (),
2175 GenericParamKind::Type { .. } => {
2176 let name = param.name.ident().name;
2177 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2180 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2181 // Params are implicitly sized unless a `?Sized` bound is found
2182 <dyn AstConv<'_>>::add_implicitly_sized(
2186 Some((param.hir_id, ast_generics.where_clause.predicates)),
2189 predicates.extend(bounds.predicates(tcx, param_ty));
2191 GenericParamKind::Const { .. } => {
2192 // Bounds on const parameters are currently not possible.
2193 debug_assert!(param.bounds.is_empty());
2199 // Add in the bounds that appear in the where-clause.
2200 let where_clause = &ast_generics.where_clause;
2201 for predicate in where_clause.predicates {
2203 hir::WherePredicate::BoundPredicate(bound_pred) => {
2204 let ty = icx.to_ty(bound_pred.bounded_ty);
2205 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2207 // Keep the type around in a dummy predicate, in case of no bounds.
2208 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2209 // is still checked for WF.
2210 if bound_pred.bounds.is_empty() {
2211 if let ty::Param(_) = ty.kind() {
2212 // This is a `where T:`, which can be in the HIR from the
2213 // transformation that moves `?Sized` to `T`'s declaration.
2214 // We can skip the predicate because type parameters are
2215 // trivially WF, but also we *should*, to avoid exposing
2216 // users who never wrote `where Type:,` themselves, to
2217 // compiler/tooling bugs from not handling WF predicates.
2219 let span = bound_pred.bounded_ty.span;
2220 let re_root_empty = tcx.lifetimes.re_root_empty;
2221 let predicate = ty::Binder::bind_with_vars(
2222 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2228 predicates.insert((predicate.to_predicate(tcx), span));
2232 let mut bounds = Bounds::default();
2233 <dyn AstConv<'_>>::add_bounds(
2236 bound_pred.bounds.iter(),
2240 predicates.extend(bounds.predicates(tcx, ty));
2243 hir::WherePredicate::RegionPredicate(region_pred) => {
2244 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2245 predicates.extend(region_pred.bounds.iter().map(|bound| {
2246 let (r2, span) = match bound {
2247 hir::GenericBound::Outlives(lt) => {
2248 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2252 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2253 ty::OutlivesPredicate(r1, r2),
2255 .to_predicate(icx.tcx);
2261 hir::WherePredicate::EqPredicate(..) => {
2267 if tcx.features().generic_const_exprs {
2268 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2271 let mut predicates: Vec<_> = predicates.into_iter().collect();
2273 // Subtle: before we store the predicates into the tcx, we
2274 // sort them so that predicates like `T: Foo<Item=U>` come
2275 // before uses of `U`. This avoids false ambiguity errors
2276 // in trait checking. See `setup_constraining_predicates`
2278 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2279 let self_ty = tcx.type_of(def_id);
2280 let trait_ref = tcx.impl_trait_ref(def_id);
2281 cgp::setup_constraining_predicates(
2285 &mut cgp::parameters_for_impl(tcx, self_ty, trait_ref),
2289 let result = ty::GenericPredicates {
2290 parent: generics.parent,
2291 predicates: tcx.arena.alloc_from_iter(predicates),
2293 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2297 fn const_evaluatable_predicates_of<'tcx>(
2300 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2301 struct ConstCollector<'tcx> {
2303 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2306 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2307 type Map = Map<'tcx>;
2309 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
2310 intravisit::NestedVisitorMap::None
2313 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2314 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2315 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2316 if let ty::ConstKind::Unevaluated(uv) = ct.val {
2317 assert_eq!(uv.promoted, None);
2318 let span = self.tcx.hir().span(c.hir_id);
2320 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2321 .to_predicate(self.tcx),
2327 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2328 // Do not look into const param defaults,
2329 // these get checked when they are actually instantiated.
2331 // We do not want the following to error:
2333 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2334 // struct Bar<const N: usize>(Foo<N, 3>);
2338 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2339 let node = tcx.hir().get(hir_id);
2341 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2342 if let hir::Node::Item(item) = node {
2343 if let hir::ItemKind::Impl(ref impl_) = item.kind {
2344 if let Some(of_trait) = &impl_.of_trait {
2345 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2346 collector.visit_trait_ref(of_trait);
2349 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2350 collector.visit_ty(impl_.self_ty);
2354 if let Some(generics) = node.generics() {
2355 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2356 collector.visit_generics(generics);
2359 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2360 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2361 collector.visit_fn_decl(fn_sig.decl);
2363 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2368 fn trait_explicit_predicates_and_bounds(
2371 ) -> ty::GenericPredicates<'_> {
2372 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2373 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2376 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2377 let def_kind = tcx.def_kind(def_id);
2378 if let DefKind::Trait = def_kind {
2379 // Remove bounds on associated types from the predicates, they will be
2380 // returned by `explicit_item_bounds`.
2381 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2382 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2384 let is_assoc_item_ty = |ty: Ty<'_>| {
2385 // For a predicate from a where clause to become a bound on an
2387 // * It must use the identity substs of the item.
2388 // * Since any generic parameters on the item are not in scope,
2389 // this means that the item is not a GAT, and its identity
2390 // substs are the same as the trait's.
2391 // * It must be an associated type for this trait (*not* a
2393 if let ty::Projection(projection) = ty.kind() {
2394 projection.substs == trait_identity_substs
2395 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2401 let predicates: Vec<_> = predicates_and_bounds
2405 .filter(|(pred, _)| match pred.kind().skip_binder() {
2406 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2407 ty::PredicateKind::Projection(proj) => {
2408 !is_assoc_item_ty(proj.projection_ty.self_ty())
2410 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2414 if predicates.len() == predicates_and_bounds.predicates.len() {
2415 predicates_and_bounds
2417 ty::GenericPredicates {
2418 parent: predicates_and_bounds.parent,
2419 predicates: tcx.arena.alloc_slice(&predicates),
2423 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2424 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2425 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2426 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2427 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2428 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2430 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2431 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2432 // ^^^ explicit_predicates_of on
2433 // parent item we dont have set as the
2434 // parent of generics returned by `generics_of`
2436 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2437 let item_id = tcx.hir().get_parent_item(hir_id);
2438 let item_def_id = tcx.hir().local_def_id(item_id).to_def_id();
2439 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2440 return tcx.explicit_predicates_of(item_def_id);
2443 gather_explicit_predicates_of(tcx, def_id)
2447 /// Converts a specific `GenericBound` from the AST into a set of
2448 /// predicates that apply to the self type. A vector is returned
2449 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2450 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2451 /// and `<T as Bar>::X == i32`).
2452 fn predicates_from_bound<'tcx>(
2453 astconv: &dyn AstConv<'tcx>,
2455 bound: &'tcx hir::GenericBound<'tcx>,
2456 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2457 let mut bounds = Bounds::default();
2460 std::array::IntoIter::new([bound]),
2464 bounds.predicates(astconv.tcx(), param_ty)
2467 fn compute_sig_of_foreign_fn_decl<'tcx>(
2470 decl: &'tcx hir::FnDecl<'tcx>,
2473 ) -> ty::PolyFnSig<'tcx> {
2474 let unsafety = if abi == abi::Abi::RustIntrinsic {
2475 intrinsic_operation_unsafety(tcx.item_name(def_id))
2477 hir::Unsafety::Unsafe
2479 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2480 let fty = <dyn AstConv<'_>>::ty_of_fn(
2481 &ItemCtxt::new(tcx, def_id),
2486 &hir::Generics::empty(),
2491 // Feature gate SIMD types in FFI, since I am not sure that the
2492 // ABIs are handled at all correctly. -huonw
2493 if abi != abi::Abi::RustIntrinsic
2494 && abi != abi::Abi::PlatformIntrinsic
2495 && !tcx.features().simd_ffi
2497 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2502 .span_to_snippet(ast_ty.span)
2503 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2508 "use of SIMD type{} in FFI is highly experimental and \
2509 may result in invalid code",
2513 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2517 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2520 if let hir::FnRetTy::Return(ref ty) = decl.output {
2521 check(ty, fty.output().skip_binder())
2528 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2529 match tcx.hir().get_if_local(def_id) {
2530 Some(Node::ForeignItem(..)) => true,
2532 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2536 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2537 match tcx.hir().get_if_local(def_id) {
2539 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2540 | Node::ForeignItem(&hir::ForeignItem {
2541 kind: hir::ForeignItemKind::Static(_, mutbl),
2546 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2550 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2551 match tcx.hir().get_if_local(def_id) {
2552 Some(Node::Expr(&rustc_hir::Expr {
2553 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2555 })) => tcx.hir().body(body_id).generator_kind(),
2557 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2561 fn from_target_feature(
2564 attr: &ast::Attribute,
2565 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2566 target_features: &mut Vec<Symbol>,
2568 let list = match attr.meta_item_list() {
2572 let bad_item = |span| {
2573 let msg = "malformed `target_feature` attribute input";
2574 let code = "enable = \"..\"".to_owned();
2576 .struct_span_err(span, msg)
2577 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2580 let rust_features = tcx.features();
2582 // Only `enable = ...` is accepted in the meta-item list.
2583 if !item.has_name(sym::enable) {
2584 bad_item(item.span());
2588 // Must be of the form `enable = "..."` (a string).
2589 let value = match item.value_str() {
2590 Some(value) => value,
2592 bad_item(item.span());
2597 // We allow comma separation to enable multiple features.
2598 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2599 let feature_gate = match supported_target_features.get(feature) {
2603 format!("the feature named `{}` is not valid for this target", feature);
2604 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2607 format!("`{}` is not valid for this target", feature),
2609 if let Some(stripped) = feature.strip_prefix('+') {
2610 let valid = supported_target_features.contains_key(stripped);
2612 err.help("consider removing the leading `+` in the feature name");
2620 // Only allow features whose feature gates have been enabled.
2621 let allowed = match feature_gate.as_ref().copied() {
2622 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2623 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2624 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2625 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2626 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2627 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2628 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2629 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2630 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2631 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2632 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2633 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2634 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2635 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2636 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2637 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2638 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2639 Some(name) => bug!("unknown target feature gate {}", name),
2642 if !allowed && id.is_local() {
2644 &tcx.sess.parse_sess,
2645 feature_gate.unwrap(),
2647 &format!("the target feature `{}` is currently unstable", feature),
2651 Some(Symbol::intern(feature))
2656 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2657 use rustc_middle::mir::mono::Linkage::*;
2659 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2660 // applicable to variable declarations and may not really make sense for
2661 // Rust code in the first place but allow them anyway and trust that the
2662 // user knows what s/he's doing. Who knows, unanticipated use cases may pop
2663 // up in the future.
2665 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2666 // and don't have to be, LLVM treats them as no-ops.
2668 "appending" => Appending,
2669 "available_externally" => AvailableExternally,
2671 "extern_weak" => ExternalWeak,
2672 "external" => External,
2673 "internal" => Internal,
2674 "linkonce" => LinkOnceAny,
2675 "linkonce_odr" => LinkOnceODR,
2676 "private" => Private,
2678 "weak_odr" => WeakODR,
2680 let span = tcx.hir().span_if_local(def_id);
2681 if let Some(span) = span {
2682 tcx.sess.span_fatal(span, "invalid linkage specified")
2684 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2690 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2691 let attrs = tcx.get_attrs(id);
2693 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2694 if tcx.should_inherit_track_caller(id) {
2695 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2698 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2699 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2700 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2701 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2705 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2707 let mut inline_span = None;
2708 let mut link_ordinal_span = None;
2709 let mut no_sanitize_span = None;
2710 for attr in attrs.iter() {
2711 if attr.has_name(sym::cold) {
2712 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2713 } else if attr.has_name(sym::rustc_allocator) {
2714 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2715 } else if attr.has_name(sym::ffi_returns_twice) {
2716 if tcx.is_foreign_item(id) {
2717 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2719 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2724 "`#[ffi_returns_twice]` may only be used on foreign functions"
2728 } else if attr.has_name(sym::ffi_pure) {
2729 if tcx.is_foreign_item(id) {
2730 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2731 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2736 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2740 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2743 // `#[ffi_pure]` is only allowed on foreign functions
2748 "`#[ffi_pure]` may only be used on foreign functions"
2752 } else if attr.has_name(sym::ffi_const) {
2753 if tcx.is_foreign_item(id) {
2754 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2756 // `#[ffi_const]` is only allowed on foreign functions
2761 "`#[ffi_const]` may only be used on foreign functions"
2765 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2766 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2767 } else if attr.has_name(sym::naked) {
2768 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2769 } else if attr.has_name(sym::no_mangle) {
2770 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2771 } else if attr.has_name(sym::no_coverage) {
2772 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2773 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2774 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2775 } else if attr.has_name(sym::used) {
2776 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2777 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2778 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2783 "`#[cmse_nonsecure_entry]` requires C ABI"
2787 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2788 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2791 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2792 } else if attr.has_name(sym::thread_local) {
2793 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2794 } else if attr.has_name(sym::track_caller) {
2795 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2796 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2799 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2801 &tcx.sess.parse_sess,
2802 sym::closure_track_caller,
2804 "`#[track_caller]` on closures is currently unstable",
2808 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2809 } else if attr.has_name(sym::export_name) {
2810 if let Some(s) = attr.value_str() {
2811 if s.as_str().contains('\0') {
2812 // `#[export_name = ...]` will be converted to a null-terminated string,
2813 // so it may not contain any null characters.
2818 "`export_name` may not contain null characters"
2822 codegen_fn_attrs.export_name = Some(s);
2824 } else if attr.has_name(sym::target_feature) {
2825 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2826 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2827 // The `#[target_feature]` attribute is allowed on
2828 // WebAssembly targets on all functions, including safe
2829 // ones. Other targets require that `#[target_feature]` is
2830 // only applied to unsafe funtions (pending the
2831 // `target_feature_11` feature) because on most targets
2832 // execution of instructions that are not supported is
2833 // considered undefined behavior. For WebAssembly which is a
2834 // 100% safe target at execution time it's not possible to
2835 // execute undefined instructions, and even if a future
2836 // feature was added in some form for this it would be a
2837 // deterministic trap. There is no undefined behavior when
2838 // executing WebAssembly so `#[target_feature]` is allowed
2839 // on safe functions (but again, only for WebAssembly)
2841 // Note that this is also allowed if `actually_rustdoc` so
2842 // if a target is documenting some wasm-specific code then
2843 // it's not spuriously denied.
2844 } else if !tcx.features().target_feature_11 {
2845 let mut err = feature_err(
2846 &tcx.sess.parse_sess,
2847 sym::target_feature_11,
2849 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2851 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2853 } else if let Some(local_id) = id.as_local() {
2854 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2857 from_target_feature(
2861 supported_target_features,
2862 &mut codegen_fn_attrs.target_features,
2864 } else if attr.has_name(sym::linkage) {
2865 if let Some(val) = attr.value_str() {
2866 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2868 } else if attr.has_name(sym::link_section) {
2869 if let Some(val) = attr.value_str() {
2870 if val.as_str().bytes().any(|b| b == 0) {
2872 "illegal null byte in link_section \
2876 tcx.sess.span_err(attr.span, &msg);
2878 codegen_fn_attrs.link_section = Some(val);
2881 } else if attr.has_name(sym::link_name) {
2882 codegen_fn_attrs.link_name = attr.value_str();
2883 } else if attr.has_name(sym::link_ordinal) {
2884 if link_ordinal_span.is_some() {
2888 "multiple `link_ordinal` attributes on a single definition",
2892 link_ordinal_span = Some(attr.span);
2893 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2894 codegen_fn_attrs.link_ordinal = ordinal;
2896 } else if attr.has_name(sym::no_sanitize) {
2897 no_sanitize_span = Some(attr.span);
2898 if let Some(list) = attr.meta_item_list() {
2899 for item in list.iter() {
2900 if item.has_name(sym::address) {
2901 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2902 } else if item.has_name(sym::cfi) {
2903 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2904 } else if item.has_name(sym::memory) {
2905 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2906 } else if item.has_name(sym::thread) {
2907 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2908 } else if item.has_name(sym::hwaddress) {
2909 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2912 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2913 .note("expected one of: `address`, `hwaddress`, `memory` or `thread`")
2918 } else if attr.has_name(sym::instruction_set) {
2919 codegen_fn_attrs.instruction_set = match attr.meta().map(|i| i.kind) {
2920 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
2921 [NestedMetaItem::MetaItem(set)] => {
2923 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
2924 match segments.as_slice() {
2925 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
2926 if !tcx.sess.target.has_thumb_interworking {
2928 tcx.sess.diagnostic(),
2931 "target does not support `#[instruction_set]`"
2935 } else if segments[1] == sym::a32 {
2936 Some(InstructionSetAttr::ArmA32)
2937 } else if segments[1] == sym::t32 {
2938 Some(InstructionSetAttr::ArmT32)
2945 tcx.sess.diagnostic(),
2948 "invalid instruction set specified",
2957 tcx.sess.diagnostic(),
2960 "`#[instruction_set]` requires an argument"
2967 tcx.sess.diagnostic(),
2970 "cannot specify more than one instruction set"
2978 tcx.sess.diagnostic(),
2981 "must specify an instruction set"
2987 } else if attr.has_name(sym::repr) {
2988 codegen_fn_attrs.alignment = match attr.meta_item_list() {
2989 Some(items) => match items.as_slice() {
2990 [item] => match item.name_value_literal() {
2991 Some((sym::align, literal)) => {
2992 let alignment = rustc_attr::parse_alignment(&literal.kind);
2995 Ok(align) => Some(align),
2998 tcx.sess.diagnostic(),
3001 "invalid `repr(align)` attribute: {}",
3020 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3021 if !attr.has_name(sym::inline) {
3024 match attr.meta().map(|i| i.kind) {
3025 Some(MetaItemKind::Word) => InlineAttr::Hint,
3026 Some(MetaItemKind::List(ref items)) => {
3027 inline_span = Some(attr.span);
3028 if items.len() != 1 {
3030 tcx.sess.diagnostic(),
3033 "expected one argument"
3037 } else if list_contains_name(&items[..], sym::always) {
3039 } else if list_contains_name(&items[..], sym::never) {
3043 tcx.sess.diagnostic(),
3053 Some(MetaItemKind::NameValue(_)) => ia,
3058 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3059 if !attr.has_name(sym::optimize) {
3062 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3063 match attr.meta().map(|i| i.kind) {
3064 Some(MetaItemKind::Word) => {
3065 err(attr.span, "expected one argument");
3068 Some(MetaItemKind::List(ref items)) => {
3069 inline_span = Some(attr.span);
3070 if items.len() != 1 {
3071 err(attr.span, "expected one argument");
3073 } else if list_contains_name(&items[..], sym::size) {
3075 } else if list_contains_name(&items[..], sym::speed) {
3078 err(items[0].span(), "invalid argument");
3082 Some(MetaItemKind::NameValue(_)) => ia,
3087 // #73631: closures inherit `#[target_feature]` annotations
3088 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3089 let owner_id = tcx.parent(id).expect("closure should have a parent");
3092 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3095 // If a function uses #[target_feature] it can't be inlined into general
3096 // purpose functions as they wouldn't have the right target features
3097 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3099 if !codegen_fn_attrs.target_features.is_empty() {
3100 if codegen_fn_attrs.inline == InlineAttr::Always {
3101 if let Some(span) = inline_span {
3104 "cannot use `#[inline(always)]` with \
3105 `#[target_feature]`",
3111 if !codegen_fn_attrs.no_sanitize.is_empty() {
3112 if codegen_fn_attrs.inline == InlineAttr::Always {
3113 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3114 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3115 tcx.struct_span_lint_hir(
3116 lint::builtin::INLINE_NO_SANITIZE,
3120 lint.build("`no_sanitize` will have no effect after inlining")
3121 .span_note(inline_span, "inlining requested here")
3129 // Weak lang items have the same semantics as "std internal" symbols in the
3130 // sense that they're preserved through all our LTO passes and only
3131 // strippable by the linker.
3133 // Additionally weak lang items have predetermined symbol names.
3134 if tcx.is_weak_lang_item(id) {
3135 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3137 let check_name = |attr: &Attribute, sym| attr.has_name(sym);
3138 if let Some(name) = weak_lang_items::link_name(check_name, attrs) {
3139 codegen_fn_attrs.export_name = Some(name);
3140 codegen_fn_attrs.link_name = Some(name);
3142 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3144 // Internal symbols to the standard library all have no_mangle semantics in
3145 // that they have defined symbol names present in the function name. This
3146 // also applies to weak symbols where they all have known symbol names.
3147 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3148 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3151 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3152 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3153 // intrinsic functions.
3154 if let Some(name) = &codegen_fn_attrs.link_name {
3155 if name.as_str().starts_with("llvm.") {
3156 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3163 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3164 /// applied to the method prototype.
3165 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3166 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
3167 if let ty::AssocItemContainer::ImplContainer(impl_def_id) = impl_item.container {
3168 if let Some(trait_def_id) = tcx.trait_id_of_impl(impl_def_id) {
3169 if let Some(trait_item) = tcx
3170 .associated_items(trait_def_id)
3171 .filter_by_name_unhygienic(impl_item.ident.name)
3172 .find(move |trait_item| {
3173 trait_item.kind == ty::AssocKind::Fn
3174 && tcx.hygienic_eq(impl_item.ident, trait_item.ident, trait_def_id)
3178 .codegen_fn_attrs(trait_item.def_id)
3180 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3189 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3190 use rustc_ast::{Lit, LitIntType, LitKind};
3191 let meta_item_list = attr.meta_item_list();
3192 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3193 let sole_meta_list = match meta_item_list {
3194 Some([item]) => item.literal(),
3197 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3198 .note("the attribute requires exactly one argument")
3204 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3205 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3206 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3207 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3208 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3210 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3211 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3212 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3213 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3214 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3215 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3216 // about LINK.EXE failing.)
3217 if *ordinal <= u16::MAX as u128 {
3218 Some(*ordinal as u16)
3220 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3222 .struct_span_err(attr.span, &msg)
3223 .note("the value may not exceed `u16::MAX`")
3229 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3230 .note("an unsuffixed integer value, e.g., `1`, is expected")
3236 fn check_link_name_xor_ordinal(
3238 codegen_fn_attrs: &CodegenFnAttrs,
3239 inline_span: Option<Span>,
3241 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3244 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3245 if let Some(span) = inline_span {
3246 tcx.sess.span_err(span, msg);
3252 /// Checks the function annotated with `#[target_feature]` is not a safe
3253 /// trait method implementation, reporting an error if it is.
3254 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3255 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3256 let node = tcx.hir().get(hir_id);
3257 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3258 let parent_id = tcx.hir().get_parent_item(hir_id);
3259 let parent_item = tcx.hir().expect_item(parent_id);
3260 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3264 "`#[target_feature(..)]` cannot be applied to safe trait method",
3266 .span_label(attr_span, "cannot be applied to safe trait method")
3267 .span_label(tcx.def_span(id), "not an `unsafe` function")