1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::AstConv;
18 use crate::bounds::Bounds;
19 use crate::check::intrinsic::intrinsic_operation_unsafety;
20 use crate::constrained_generic_params as cgp;
22 use crate::middle::resolve_lifetime as rl;
24 use rustc_ast::{MetaItemKind, NestedMetaItem};
25 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
26 use rustc_data_structures::captures::Captures;
27 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
28 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
30 use rustc_hir::def::{CtorKind, DefKind};
31 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
32 use rustc_hir::intravisit::{self, Visitor};
33 use rustc_hir::weak_lang_items;
34 use rustc_hir::{GenericParamKind, HirId, Node};
35 use rustc_middle::hir::nested_filter;
36 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
37 use rustc_middle::mir::mono::Linkage;
38 use rustc_middle::ty::query::Providers;
39 use rustc_middle::ty::subst::InternalSubsts;
40 use rustc_middle::ty::util::Discr;
41 use rustc_middle::ty::util::IntTypeExt;
42 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
43 use rustc_middle::ty::{ReprOptions, ToPredicate};
44 use rustc_session::lint;
45 use rustc_session::parse::feature_err;
46 use rustc_span::symbol::{kw, sym, Ident, Symbol};
47 use rustc_span::{Span, DUMMY_SP};
48 use rustc_target::spec::{abi, PanicStrategy, SanitizerSet};
49 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
55 struct OnlySelfBounds(bool);
57 ///////////////////////////////////////////////////////////////////////////
60 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
61 tcx.hir().visit_item_likes_in_module(
63 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
67 pub fn provide(providers: &mut Providers) {
68 *providers = Providers {
69 opt_const_param_of: type_of::opt_const_param_of,
70 type_of: type_of::type_of,
71 item_bounds: item_bounds::item_bounds,
72 explicit_item_bounds: item_bounds::explicit_item_bounds,
75 predicates_defined_on,
76 explicit_predicates_of,
78 super_predicates_that_define_assoc_type,
79 trait_explicit_predicates_and_bounds,
80 type_param_predicates,
90 collect_mod_item_types,
91 should_inherit_track_caller,
96 ///////////////////////////////////////////////////////////////////////////
98 /// Context specific to some particular item. This is what implements
99 /// `AstConv`. It has information about the predicates that are defined
100 /// on the trait. Unfortunately, this predicate information is
101 /// available in various different forms at various points in the
102 /// process. So we can't just store a pointer to e.g., the AST or the
103 /// parsed ty form, we have to be more flexible. To this end, the
104 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
105 /// `get_type_parameter_bounds` requests, drawing the information from
106 /// the AST (`hir::Generics`), recursively.
107 pub struct ItemCtxt<'tcx> {
112 ///////////////////////////////////////////////////////////////////////////
115 crate struct HirPlaceholderCollector(crate Vec<Span>);
117 impl<'v> Visitor<'v> for HirPlaceholderCollector {
118 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
119 if let hir::TyKind::Infer = t.kind {
122 intravisit::walk_ty(self, t)
124 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
126 hir::GenericArg::Infer(inf) => {
127 self.0.push(inf.span);
128 intravisit::walk_inf(self, inf);
130 hir::GenericArg::Type(t) => self.visit_ty(t),
134 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
135 if let &hir::ArrayLen::Infer(_, span) = length {
138 intravisit::walk_array_len(self, length)
142 struct CollectItemTypesVisitor<'tcx> {
146 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
147 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
148 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
149 crate fn placeholder_type_error<'tcx>(
151 generics: Option<&hir::Generics<'_>>,
152 placeholder_types: Vec<Span>,
154 hir_ty: Option<&hir::Ty<'_>>,
157 if placeholder_types.is_empty() {
161 placeholder_type_error_diag(tcx, generics, placeholder_types, vec![], suggest, hir_ty, kind)
165 crate fn placeholder_type_error_diag<'tcx>(
167 generics: Option<&hir::Generics<'_>>,
168 placeholder_types: Vec<Span>,
169 additional_spans: Vec<Span>,
171 hir_ty: Option<&hir::Ty<'_>>,
173 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
174 if placeholder_types.is_empty() {
175 return bad_placeholder(tcx, additional_spans, kind);
178 let params = generics.map(|g| g.params).unwrap_or_default();
179 let type_name = params.next_type_param_name(None);
180 let mut sugg: Vec<_> =
181 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
183 if let Some(generics) = generics {
184 if let Some(arg) = params.iter().find(|arg| {
185 matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. }))
187 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
188 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
189 sugg.push((arg.span, (*type_name).to_string()));
190 } else if let Some(span) = generics.span_for_param_suggestion() {
191 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
192 sugg.push((span, format!(", {}", type_name)));
194 sugg.push((generics.span, format!("<{}>", type_name)));
199 bad_placeholder(tcx, placeholder_types.into_iter().chain(additional_spans).collect(), kind);
201 // Suggest, but only if it is not a function in const or static
203 let mut is_fn = false;
204 let mut is_const_or_static = false;
206 if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind {
209 // Check if parent is const or static
210 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
211 let parent_node = tcx.hir().get(parent_id);
213 is_const_or_static = matches!(
215 Node::Item(&hir::Item {
216 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
218 }) | Node::TraitItem(&hir::TraitItem {
219 kind: hir::TraitItemKind::Const(..),
221 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
225 // if function is wrapped around a const or static,
226 // then don't show the suggestion
227 if !(is_fn && is_const_or_static) {
228 err.multipart_suggestion(
229 "use type parameters instead",
231 Applicability::HasPlaceholders,
239 fn reject_placeholder_type_signatures_in_item<'tcx>(
241 item: &'tcx hir::Item<'tcx>,
243 let (generics, suggest) = match &item.kind {
244 hir::ItemKind::Union(_, generics)
245 | hir::ItemKind::Enum(_, generics)
246 | hir::ItemKind::TraitAlias(generics, _)
247 | hir::ItemKind::Trait(_, _, generics, ..)
248 | hir::ItemKind::Impl(hir::Impl { generics, .. })
249 | hir::ItemKind::Struct(_, generics) => (generics, true),
250 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
251 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
252 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
256 let mut visitor = HirPlaceholderCollector::default();
257 visitor.visit_item(item);
259 placeholder_type_error(tcx, Some(generics), visitor.0, suggest, None, item.kind.descr());
262 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
263 type NestedFilter = nested_filter::OnlyBodies;
265 fn nested_visit_map(&mut self) -> Self::Map {
269 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
270 convert_item(self.tcx, item.item_id());
271 reject_placeholder_type_signatures_in_item(self.tcx, item);
272 intravisit::walk_item(self, item);
275 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
276 for param in generics.params {
278 hir::GenericParamKind::Lifetime { .. } => {}
279 hir::GenericParamKind::Type { default: Some(_), .. } => {
280 let def_id = self.tcx.hir().local_def_id(param.hir_id);
281 self.tcx.ensure().type_of(def_id);
283 hir::GenericParamKind::Type { .. } => {}
284 hir::GenericParamKind::Const { default, .. } => {
285 let def_id = self.tcx.hir().local_def_id(param.hir_id);
286 self.tcx.ensure().type_of(def_id);
287 if let Some(default) = default {
288 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
289 // need to store default and type of default
290 self.tcx.ensure().type_of(default_def_id);
291 self.tcx.ensure().const_param_default(def_id);
296 intravisit::walk_generics(self, generics);
299 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
300 if let hir::ExprKind::Closure(..) = expr.kind {
301 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
302 self.tcx.ensure().generics_of(def_id);
303 // We do not call `type_of` for closures here as that
304 // depends on typecheck and would therefore hide
305 // any further errors in case one typeck fails.
307 intravisit::walk_expr(self, expr);
310 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
311 convert_trait_item(self.tcx, trait_item.trait_item_id());
312 intravisit::walk_trait_item(self, trait_item);
315 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
316 convert_impl_item(self.tcx, impl_item.impl_item_id());
317 intravisit::walk_impl_item(self, impl_item);
321 ///////////////////////////////////////////////////////////////////////////
322 // Utility types and common code for the above passes.
324 fn bad_placeholder<'tcx>(
326 mut spans: Vec<Span>,
328 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
329 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
332 let mut err = struct_span_err!(
336 "the placeholder `_` is not allowed within types on item signatures for {}",
340 err.span_label(span, "not allowed in type signatures");
345 impl<'tcx> ItemCtxt<'tcx> {
346 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
347 ItemCtxt { tcx, item_def_id }
350 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
351 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
354 pub fn hir_id(&self) -> hir::HirId {
355 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
358 pub fn node(&self) -> hir::Node<'tcx> {
359 self.tcx.hir().get(self.hir_id())
363 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
364 fn tcx(&self) -> TyCtxt<'tcx> {
368 fn item_def_id(&self) -> Option<DefId> {
369 Some(self.item_def_id)
372 fn get_type_parameter_bounds(
377 ) -> ty::GenericPredicates<'tcx> {
378 self.tcx.at(span).type_param_predicates((
380 def_id.expect_local(),
385 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
389 fn allow_ty_infer(&self) -> bool {
393 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
394 self.tcx().ty_error_with_message(span, "bad placeholder type")
397 fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
398 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match *r {
399 ty::ReErased => self.tcx.lifetimes.re_static,
402 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
405 fn projected_ty_from_poly_trait_ref(
409 item_segment: &hir::PathSegment<'_>,
410 poly_trait_ref: ty::PolyTraitRef<'tcx>,
412 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
413 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
421 self.tcx().mk_projection(item_def_id, item_substs)
423 // There are no late-bound regions; we can just ignore the binder.
424 let mut err = struct_span_err!(
428 "cannot use the associated type of a trait \
429 with uninferred generic parameters"
433 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
435 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
437 hir::ItemKind::Enum(_, generics)
438 | hir::ItemKind::Struct(_, generics)
439 | hir::ItemKind::Union(_, generics) => {
440 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
441 let (lt_sp, sugg) = match generics.params {
442 [] => (generics.span, format!("<{}>", lt_name)),
444 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
447 let suggestions = vec![
450 span.with_hi(item_segment.ident.span.lo()),
453 // Replace the existing lifetimes with a new named lifetime.
455 .replace_late_bound_regions(poly_trait_ref, |_| {
456 self.tcx.mk_region(ty::ReEarlyBound(
457 ty::EarlyBoundRegion {
460 name: Symbol::intern(<_name),
468 err.multipart_suggestion(
469 "use a fully qualified path with explicit lifetimes",
471 Applicability::MaybeIncorrect,
477 hir::Node::Item(hir::Item {
479 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
483 | hir::Node::ForeignItem(_)
484 | hir::Node::TraitItem(_)
485 | hir::Node::ImplItem(_) => {
486 err.span_suggestion_verbose(
487 span.with_hi(item_segment.ident.span.lo()),
488 "use a fully qualified path with inferred lifetimes",
491 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
492 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
494 Applicability::MaybeIncorrect,
500 self.tcx().ty_error()
504 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
505 // Types in item signatures are not normalized to avoid undue dependencies.
509 fn set_tainted_by_errors(&self) {
510 // There's no obvious place to track this, so just let it go.
513 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
514 // There's no place to record types from signatures?
518 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
519 fn get_new_lifetime_name<'tcx>(
521 poly_trait_ref: ty::PolyTraitRef<'tcx>,
522 generics: &hir::Generics<'tcx>,
524 let existing_lifetimes = tcx
525 .collect_referenced_late_bound_regions(&poly_trait_ref)
528 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
529 Some(name.as_str().to_string())
534 .chain(generics.params.iter().filter_map(|param| {
535 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
536 Some(param.name.ident().as_str().to_string())
541 .collect::<FxHashSet<String>>();
543 let a_to_z_repeat_n = |n| {
544 (b'a'..=b'z').map(move |c| {
545 let mut s = '\''.to_string();
546 s.extend(std::iter::repeat(char::from(c)).take(n));
551 // If all single char lifetime names are present, we wrap around and double the chars.
552 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
555 /// Returns the predicates defined on `item_def_id` of the form
556 /// `X: Foo` where `X` is the type parameter `def_id`.
557 fn type_param_predicates(
559 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
560 ) -> ty::GenericPredicates<'_> {
563 // In the AST, bounds can derive from two places. Either
564 // written inline like `<T: Foo>` or in a where-clause like
567 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
568 let param_owner = tcx.hir().ty_param_owner(def_id);
569 let generics = tcx.generics_of(param_owner);
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(def_id));
573 // Don't look for bounds where the type parameter isn't in scope.
574 let parent = if item_def_id == param_owner.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 {
601 origin: hir::OpaqueTyOrigin::TyAlias,
604 | ItemKind::Enum(_, ref generics)
605 | ItemKind::Struct(_, ref generics)
606 | ItemKind::Union(_, ref generics) => generics,
607 ItemKind::Trait(_, _, ref generics, ..) => {
608 // Implied `Self: Trait` and supertrait bounds.
609 if param_id == item_hir_id {
610 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
612 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
620 Node::ForeignItem(item) => match item.kind {
621 ForeignItemKind::Fn(_, _, ref generics) => generics,
628 let icx = ItemCtxt::new(tcx, item_def_id);
629 let extra_predicates = extend.into_iter().chain(
630 icx.type_parameter_bounds_in_generics(
634 OnlySelfBounds(true),
638 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
639 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
644 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
648 impl<'tcx> ItemCtxt<'tcx> {
649 /// Finds bounds from `hir::Generics`. This requires scanning through the
650 /// AST. We do this to avoid having to convert *all* the bounds, which
651 /// would create artificial cycles. Instead, we can only convert the
652 /// bounds for a type parameter `X` if `X::Foo` is used.
653 fn type_parameter_bounds_in_generics(
655 ast_generics: &'tcx hir::Generics<'tcx>,
656 param_id: hir::HirId,
658 only_self_bounds: OnlySelfBounds,
659 assoc_name: Option<Ident>,
660 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
661 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
665 .filter_map(|wp| match *wp {
666 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
670 let bt = if bp.is_param_bound(param_def_id) {
672 } else if !only_self_bounds.0 {
673 Some(self.to_ty(bp.bounded_ty))
677 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
681 .filter(|b| match assoc_name {
682 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
685 .filter_map(move |b| bt.map(|bt| (bt, b, bvars)))
687 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars))
691 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
692 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
695 hir::GenericBound::Trait(poly_trait_ref, _) => {
696 let trait_ref = &poly_trait_ref.trait_ref;
697 if let Some(trait_did) = trait_ref.trait_def_id() {
698 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
708 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
709 let it = tcx.hir().item(item_id);
710 debug!("convert: item {} with id {}", it.ident, it.hir_id());
711 let def_id = item_id.def_id;
714 // These don't define types.
715 hir::ItemKind::ExternCrate(_)
716 | hir::ItemKind::Use(..)
717 | hir::ItemKind::Macro(..)
718 | hir::ItemKind::Mod(_)
719 | hir::ItemKind::GlobalAsm(_) => {}
720 hir::ItemKind::ForeignMod { items, .. } => {
722 let item = tcx.hir().foreign_item(item.id);
723 tcx.ensure().generics_of(item.def_id);
724 tcx.ensure().type_of(item.def_id);
725 tcx.ensure().predicates_of(item.def_id);
727 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
728 hir::ForeignItemKind::Static(..) => {
729 let mut visitor = HirPlaceholderCollector::default();
730 visitor.visit_foreign_item(item);
731 placeholder_type_error(
744 hir::ItemKind::Enum(ref enum_definition, _) => {
745 tcx.ensure().generics_of(def_id);
746 tcx.ensure().type_of(def_id);
747 tcx.ensure().predicates_of(def_id);
748 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
750 hir::ItemKind::Impl { .. } => {
751 tcx.ensure().generics_of(def_id);
752 tcx.ensure().type_of(def_id);
753 tcx.ensure().impl_trait_ref(def_id);
754 tcx.ensure().predicates_of(def_id);
756 hir::ItemKind::Trait(..) => {
757 tcx.ensure().generics_of(def_id);
758 tcx.ensure().trait_def(def_id);
759 tcx.at(it.span).super_predicates_of(def_id);
760 tcx.ensure().predicates_of(def_id);
762 hir::ItemKind::TraitAlias(..) => {
763 tcx.ensure().generics_of(def_id);
764 tcx.at(it.span).super_predicates_of(def_id);
765 tcx.ensure().predicates_of(def_id);
767 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
768 tcx.ensure().generics_of(def_id);
769 tcx.ensure().type_of(def_id);
770 tcx.ensure().predicates_of(def_id);
772 for f in struct_def.fields() {
773 let def_id = tcx.hir().local_def_id(f.hir_id);
774 tcx.ensure().generics_of(def_id);
775 tcx.ensure().type_of(def_id);
776 tcx.ensure().predicates_of(def_id);
779 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
780 convert_variant_ctor(tcx, ctor_hir_id);
784 // Desugared from `impl Trait`, so visited by the function's return type.
785 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
786 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
790 // Don't call `type_of` on opaque types, since that depends on type
791 // checking function bodies. `check_item_type` ensures that it's called
793 hir::ItemKind::OpaqueTy(..) => {
794 tcx.ensure().generics_of(def_id);
795 tcx.ensure().predicates_of(def_id);
796 tcx.ensure().explicit_item_bounds(def_id);
798 hir::ItemKind::TyAlias(..)
799 | hir::ItemKind::Static(..)
800 | hir::ItemKind::Const(..)
801 | hir::ItemKind::Fn(..) => {
802 tcx.ensure().generics_of(def_id);
803 tcx.ensure().type_of(def_id);
804 tcx.ensure().predicates_of(def_id);
806 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
807 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
808 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
809 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
810 if let hir::TyKind::TraitObject(..) = ty.kind {
811 let mut visitor = HirPlaceholderCollector::default();
812 visitor.visit_item(it);
813 placeholder_type_error(tcx, None, visitor.0, false, None, it.kind.descr());
822 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
823 let trait_item = tcx.hir().trait_item(trait_item_id);
824 tcx.ensure().generics_of(trait_item_id.def_id);
826 match trait_item.kind {
827 hir::TraitItemKind::Fn(..) => {
828 tcx.ensure().type_of(trait_item_id.def_id);
829 tcx.ensure().fn_sig(trait_item_id.def_id);
832 hir::TraitItemKind::Const(.., Some(_)) => {
833 tcx.ensure().type_of(trait_item_id.def_id);
836 hir::TraitItemKind::Const(..) => {
837 tcx.ensure().type_of(trait_item_id.def_id);
838 // Account for `const C: _;`.
839 let mut visitor = HirPlaceholderCollector::default();
840 visitor.visit_trait_item(trait_item);
841 placeholder_type_error(tcx, None, visitor.0, false, None, "constant");
844 hir::TraitItemKind::Type(_, Some(_)) => {
845 tcx.ensure().item_bounds(trait_item_id.def_id);
846 tcx.ensure().type_of(trait_item_id.def_id);
847 // Account for `type T = _;`.
848 let mut visitor = HirPlaceholderCollector::default();
849 visitor.visit_trait_item(trait_item);
850 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
853 hir::TraitItemKind::Type(_, None) => {
854 tcx.ensure().item_bounds(trait_item_id.def_id);
855 // #74612: Visit and try to find bad placeholders
856 // even if there is no concrete type.
857 let mut visitor = HirPlaceholderCollector::default();
858 visitor.visit_trait_item(trait_item);
860 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
864 tcx.ensure().predicates_of(trait_item_id.def_id);
867 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
868 let def_id = impl_item_id.def_id;
869 tcx.ensure().generics_of(def_id);
870 tcx.ensure().type_of(def_id);
871 tcx.ensure().predicates_of(def_id);
872 let impl_item = tcx.hir().impl_item(impl_item_id);
873 match impl_item.kind {
874 hir::ImplItemKind::Fn(..) => {
875 tcx.ensure().fn_sig(def_id);
877 hir::ImplItemKind::TyAlias(_) => {
878 // Account for `type T = _;`
879 let mut visitor = HirPlaceholderCollector::default();
880 visitor.visit_impl_item(impl_item);
882 placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
884 hir::ImplItemKind::Const(..) => {}
888 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
889 let def_id = tcx.hir().local_def_id(ctor_id);
890 tcx.ensure().generics_of(def_id);
891 tcx.ensure().type_of(def_id);
892 tcx.ensure().predicates_of(def_id);
895 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
896 let def = tcx.adt_def(def_id);
897 let repr_type = def.repr().discr_type();
898 let initial = repr_type.initial_discriminant(tcx);
899 let mut prev_discr = None::<Discr<'_>>;
901 // fill the discriminant values and field types
902 for variant in variants {
903 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
905 if let Some(ref e) = variant.disr_expr {
906 let expr_did = tcx.hir().local_def_id(e.hir_id);
907 def.eval_explicit_discr(tcx, expr_did.to_def_id())
908 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
911 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
914 format!("overflowed on value after {}", prev_discr.unwrap()),
917 "explicitly set `{} = {}` if that is desired outcome",
918 variant.ident, wrapped_discr
923 .unwrap_or(wrapped_discr),
926 for f in variant.data.fields() {
927 let def_id = tcx.hir().local_def_id(f.hir_id);
928 tcx.ensure().generics_of(def_id);
929 tcx.ensure().type_of(def_id);
930 tcx.ensure().predicates_of(def_id);
933 // Convert the ctor, if any. This also registers the variant as
935 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
936 convert_variant_ctor(tcx, ctor_hir_id);
943 variant_did: Option<LocalDefId>,
944 ctor_did: Option<LocalDefId>,
946 discr: ty::VariantDiscr,
947 def: &hir::VariantData<'_>,
948 adt_kind: ty::AdtKind,
949 parent_did: LocalDefId,
950 ) -> ty::VariantDef {
951 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
956 let fid = tcx.hir().local_def_id(f.hir_id);
957 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
958 if let Some(prev_span) = dup_span {
959 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
965 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
968 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
971 let recovered = match def {
972 hir::VariantData::Struct(_, r) => *r,
977 variant_did.map(LocalDefId::to_def_id),
978 ctor_did.map(LocalDefId::to_def_id),
981 CtorKind::from_hir(def),
983 parent_did.to_def_id(),
985 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
986 || variant_did.map_or(false, |variant_did| {
987 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
992 fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
995 let def_id = def_id.expect_local();
996 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
997 let Node::Item(item) = tcx.hir().get(hir_id) else {
1001 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1002 let (kind, variants) = match item.kind {
1003 ItemKind::Enum(ref def, _) => {
1004 let mut distance_from_explicit = 0;
1009 let variant_did = Some(tcx.hir().local_def_id(v.id));
1011 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1013 let discr = if let Some(ref e) = v.disr_expr {
1014 distance_from_explicit = 0;
1015 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1017 ty::VariantDiscr::Relative(distance_from_explicit)
1019 distance_from_explicit += 1;
1034 (AdtKind::Enum, variants)
1036 ItemKind::Struct(ref def, _) => {
1037 let variant_did = None::<LocalDefId>;
1038 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1040 let variants = std::iter::once(convert_variant(
1045 ty::VariantDiscr::Relative(0),
1052 (AdtKind::Struct, variants)
1054 ItemKind::Union(ref def, _) => {
1055 let variant_did = None;
1056 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1058 let variants = std::iter::once(convert_variant(
1063 ty::VariantDiscr::Relative(0),
1070 (AdtKind::Union, variants)
1074 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1077 /// Ensures that the super-predicates of the trait with a `DefId`
1078 /// of `trait_def_id` are converted and stored. This also ensures that
1079 /// the transitive super-predicates are converted.
1080 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1081 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1082 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1085 /// Ensures that the super-predicates of the trait with a `DefId`
1086 /// of `trait_def_id` are converted and stored. This also ensures that
1087 /// the transitive super-predicates are converted.
1088 fn super_predicates_that_define_assoc_type(
1090 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1091 ) -> ty::GenericPredicates<'_> {
1093 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1094 trait_def_id, assoc_name
1096 if trait_def_id.is_local() {
1097 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1098 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1100 let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
1101 bug!("trait_node_id {} is not an item", trait_hir_id);
1104 let (generics, bounds) = match item.kind {
1105 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1106 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1107 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1110 let icx = ItemCtxt::new(tcx, trait_def_id);
1112 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1113 let self_param_ty = tcx.types.self_param;
1114 let superbounds1 = if let Some(assoc_name) = assoc_name {
1115 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1122 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1125 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1127 // Convert any explicit superbounds in the where-clause,
1128 // e.g., `trait Foo where Self: Bar`.
1129 // In the case of trait aliases, however, we include all bounds in the where-clause,
1130 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1131 // as one of its "superpredicates".
1132 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1133 let superbounds2 = icx.type_parameter_bounds_in_generics(
1137 OnlySelfBounds(!is_trait_alias),
1141 // Combine the two lists to form the complete set of superbounds:
1142 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1144 // Now require that immediate supertraits are converted,
1145 // which will, in turn, reach indirect supertraits.
1146 if assoc_name.is_none() {
1147 // Now require that immediate supertraits are converted,
1148 // which will, in turn, reach indirect supertraits.
1149 for &(pred, span) in superbounds {
1150 debug!("superbound: {:?}", pred);
1151 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1152 tcx.at(span).super_predicates_of(bound.def_id());
1157 ty::GenericPredicates { parent: None, predicates: superbounds }
1159 // if `assoc_name` is None, then the query should've been redirected to an
1160 // external provider
1161 assert!(assoc_name.is_some());
1162 tcx.super_predicates_of(trait_def_id)
1166 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1167 let item = tcx.hir().expect_item(def_id.expect_local());
1169 let (is_auto, unsafety, items) = match item.kind {
1170 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1171 (is_auto == hir::IsAuto::Yes, unsafety, items)
1173 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1174 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1177 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1178 if paren_sugar && !tcx.features().unboxed_closures {
1182 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1183 which traits can use parenthetical notation",
1185 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1189 let is_marker = tcx.has_attr(def_id, sym::marker);
1190 let skip_array_during_method_dispatch =
1191 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1192 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1193 ty::trait_def::TraitSpecializationKind::Marker
1194 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1195 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1197 ty::trait_def::TraitSpecializationKind::None
1199 let must_implement_one_of = tcx
1202 .find(|attr| attr.has_name(sym::rustc_must_implement_one_of))
1203 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1204 // and that they are all identifiers
1205 .and_then(|attr| match attr.meta_item_list() {
1206 Some(items) if items.len() < 2 => {
1210 "the `#[rustc_must_implement_one_of]` attribute must be \
1211 used with at least 2 args",
1217 Some(items) => items
1219 .map(|item| item.ident().ok_or(item.span()))
1220 .collect::<Result<Box<[_]>, _>>()
1223 .struct_span_err(span, "must be a name of an associated function")
1227 .zip(Some(attr.span)),
1228 // Error is reported by `rustc_attr!`
1231 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1232 // functions in the trait with default implementations
1233 .and_then(|(list, attr_span)| {
1234 let errors = list.iter().filter_map(|ident| {
1235 let item = items.iter().find(|item| item.ident == *ident);
1238 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1239 if !item.defaultness.has_value() {
1243 "This function doesn't have a default implementation",
1245 .span_note(attr_span, "required by this annotation")
1255 .struct_span_err(item.span, "Not a function")
1256 .span_note(attr_span, "required by this annotation")
1258 "All `#[rustc_must_implement_one_of]` arguments \
1259 must be associated function names",
1265 .struct_span_err(ident.span, "Function not found in this trait")
1273 (errors.count() == 0).then_some(list)
1275 // Check for duplicates
1277 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1278 let mut no_dups = true;
1280 for ident in &*list {
1281 if let Some(dup) = set.insert(ident.name, ident.span) {
1283 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1285 "All `#[rustc_must_implement_one_of]` arguments \
1294 no_dups.then_some(list)
1303 skip_array_during_method_dispatch,
1305 must_implement_one_of,
1309 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1310 struct LateBoundRegionsDetector<'tcx> {
1312 outer_index: ty::DebruijnIndex,
1313 has_late_bound_regions: Option<Span>,
1316 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1317 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1318 if self.has_late_bound_regions.is_some() {
1322 hir::TyKind::BareFn(..) => {
1323 self.outer_index.shift_in(1);
1324 intravisit::walk_ty(self, ty);
1325 self.outer_index.shift_out(1);
1327 _ => intravisit::walk_ty(self, ty),
1331 fn visit_poly_trait_ref(
1333 tr: &'tcx hir::PolyTraitRef<'tcx>,
1334 m: hir::TraitBoundModifier,
1336 if self.has_late_bound_regions.is_some() {
1339 self.outer_index.shift_in(1);
1340 intravisit::walk_poly_trait_ref(self, tr, m);
1341 self.outer_index.shift_out(1);
1344 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1345 if self.has_late_bound_regions.is_some() {
1349 match self.tcx.named_region(lt.hir_id) {
1350 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1352 rl::Region::LateBound(debruijn, _, _)
1353 | rl::Region::LateBoundAnon(debruijn, _, _),
1354 ) if debruijn < self.outer_index => {}
1356 rl::Region::LateBound(..)
1357 | rl::Region::LateBoundAnon(..)
1358 | rl::Region::Free(..),
1361 self.has_late_bound_regions = Some(lt.span);
1367 fn has_late_bound_regions<'tcx>(
1370 generics: &'tcx hir::Generics<'tcx>,
1371 decl: &'tcx hir::FnDecl<'tcx>,
1373 let mut visitor = LateBoundRegionsDetector {
1375 outer_index: ty::INNERMOST,
1376 has_late_bound_regions: None,
1378 let late_bound_map = tcx.is_late_bound_map(def_id);
1379 let is_late_bound = |id| {
1380 let id = tcx.hir().local_def_id(id);
1381 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
1383 for param in generics.params {
1384 if let GenericParamKind::Lifetime { .. } = param.kind {
1385 if is_late_bound(param.hir_id) {
1386 return Some(param.span);
1390 visitor.visit_fn_decl(decl);
1391 visitor.has_late_bound_regions
1395 Node::TraitItem(item) => match item.kind {
1396 hir::TraitItemKind::Fn(ref sig, _) => {
1397 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1401 Node::ImplItem(item) => match item.kind {
1402 hir::ImplItemKind::Fn(ref sig, _) => {
1403 has_late_bound_regions(tcx, item.def_id, &item.generics, sig.decl)
1407 Node::ForeignItem(item) => match item.kind {
1408 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1409 has_late_bound_regions(tcx, item.def_id, generics, fn_decl)
1413 Node::Item(item) => match item.kind {
1414 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1415 has_late_bound_regions(tcx, item.def_id, generics, sig.decl)
1423 struct AnonConstInParamTyDetector {
1425 found_anon_const_in_param_ty: bool,
1429 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1430 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1431 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1432 let prev = self.in_param_ty;
1433 self.in_param_ty = true;
1435 self.in_param_ty = prev;
1439 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1440 if self.in_param_ty && self.ct == c.hir_id {
1441 self.found_anon_const_in_param_ty = true;
1443 intravisit::walk_anon_const(self, c)
1448 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1451 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1453 let node = tcx.hir().get(hir_id);
1454 let parent_def_id = match node {
1456 | Node::TraitItem(_)
1459 | Node::Field(_) => {
1460 let parent_id = tcx.hir().get_parent_item(hir_id);
1461 Some(parent_id.to_def_id())
1463 // FIXME(#43408) always enable this once `lazy_normalization` is
1464 // stable enough and does not need a feature gate anymore.
1465 Node::AnonConst(_) => {
1466 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1468 let mut in_param_ty = false;
1469 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1470 if let Some(generics) = node.generics() {
1471 let mut visitor = AnonConstInParamTyDetector {
1473 found_anon_const_in_param_ty: false,
1477 visitor.visit_generics(generics);
1478 in_param_ty = visitor.found_anon_const_in_param_ty;
1484 // We do not allow generic parameters in anon consts if we are inside
1485 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1487 } else if tcx.lazy_normalization() {
1488 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1489 // If the def_id we are calling generics_of on is an anon ct default i.e:
1491 // struct Foo<const N: usize = { .. }>;
1492 // ^^^ ^ ^^^^^^ def id of this anon const
1496 // then we only want to return generics for params to the left of `N`. If we don't do that we
1497 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1499 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1500 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1501 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1503 // We fix this by having this function return the parent's generics ourselves and truncating the
1504 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1506 // For the above code example that means we want `substs: []`
1507 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1508 // the def id of the `{ N + 1 }` anon const
1509 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1511 // This has some implications for how we get the predicates available to the anon const
1512 // see `explicit_predicates_of` for more information on this
1513 let generics = tcx.generics_of(parent_def_id.to_def_id());
1514 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1515 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1516 // In the above example this would be .params[..N#0]
1517 let params = generics.params[..param_def_idx as usize].to_owned();
1518 let param_def_id_to_index =
1519 params.iter().map(|param| (param.def_id, param.index)).collect();
1521 return ty::Generics {
1522 // we set the parent of these generics to be our parent's parent so that we
1523 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1524 // struct Foo<const N: usize, const M: usize = { ... }>;
1525 parent: generics.parent,
1526 parent_count: generics.parent_count,
1528 param_def_id_to_index,
1529 has_self: generics.has_self,
1530 has_late_bound_regions: generics.has_late_bound_regions,
1534 // HACK(eddyb) this provides the correct generics when
1535 // `feature(generic_const_expressions)` is enabled, so that const expressions
1536 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1538 // Note that we do not supply the parent generics when using
1539 // `min_const_generics`.
1540 Some(parent_def_id.to_def_id())
1542 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1544 // HACK(eddyb) this provides the correct generics for repeat
1545 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1546 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1547 // as they shouldn't be able to cause query cycle errors.
1548 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1549 if constant.hir_id() == hir_id =>
1551 Some(parent_def_id.to_def_id())
1553 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1554 if constant.hir_id == hir_id =>
1556 Some(parent_def_id.to_def_id())
1558 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1559 Some(tcx.typeck_root_def_id(def_id))
1565 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1566 Some(tcx.typeck_root_def_id(def_id))
1568 Node::Item(item) => match item.kind {
1569 ItemKind::OpaqueTy(hir::OpaqueTy {
1571 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1573 }) => Some(fn_def_id.to_def_id()),
1574 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1575 let parent_id = tcx.hir().get_parent_item(hir_id);
1576 assert_ne!(parent_id, CRATE_DEF_ID);
1577 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1578 // Opaque types are always nested within another item, and
1579 // inherit the generics of the item.
1580 Some(parent_id.to_def_id())
1587 let mut opt_self = None;
1588 let mut allow_defaults = false;
1590 let no_generics = hir::Generics::empty();
1591 let ast_generics = match node {
1592 Node::TraitItem(item) => &item.generics,
1594 Node::ImplItem(item) => &item.generics,
1596 Node::Item(item) => {
1598 ItemKind::Fn(.., ref generics, _)
1599 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1601 ItemKind::TyAlias(_, ref generics)
1602 | ItemKind::Enum(_, ref generics)
1603 | ItemKind::Struct(_, ref generics)
1604 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1605 | ItemKind::Union(_, ref generics) => {
1606 allow_defaults = true;
1610 ItemKind::Trait(_, _, ref generics, ..)
1611 | ItemKind::TraitAlias(ref generics, ..) => {
1612 // Add in the self type parameter.
1614 // Something of a hack: use the node id for the trait, also as
1615 // the node id for the Self type parameter.
1616 let param_id = item.def_id;
1618 opt_self = Some(ty::GenericParamDef {
1620 name: kw::SelfUpper,
1621 def_id: param_id.to_def_id(),
1622 pure_wrt_drop: false,
1623 kind: ty::GenericParamDefKind::Type {
1625 object_lifetime_default: rl::Set1::Empty,
1630 allow_defaults = true;
1638 Node::ForeignItem(item) => match item.kind {
1639 ForeignItemKind::Static(..) => &no_generics,
1640 ForeignItemKind::Fn(_, _, ref generics) => generics,
1641 ForeignItemKind::Type => &no_generics,
1647 let has_self = opt_self.is_some();
1648 let mut parent_has_self = false;
1649 let mut own_start = has_self as u32;
1650 let parent_count = parent_def_id.map_or(0, |def_id| {
1651 let generics = tcx.generics_of(def_id);
1653 parent_has_self = generics.has_self;
1654 own_start = generics.count() as u32;
1655 generics.parent_count + generics.params.len()
1658 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1660 if let Some(opt_self) = opt_self {
1661 params.push(opt_self);
1664 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics);
1665 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1666 name: param.name.ident().name,
1667 index: own_start + i as u32,
1668 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1669 pure_wrt_drop: param.pure_wrt_drop,
1670 kind: ty::GenericParamDefKind::Lifetime,
1673 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id.owner);
1675 // Now create the real type and const parameters.
1676 let type_start = own_start - has_self as u32 + params.len() as u32;
1679 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1680 GenericParamKind::Lifetime { .. } => None,
1681 GenericParamKind::Type { ref default, synthetic, .. } => {
1682 if !allow_defaults && default.is_some() {
1683 if !tcx.features().default_type_parameter_fallback {
1684 tcx.struct_span_lint_hir(
1685 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1690 "defaults for type parameters are only allowed in \
1691 `struct`, `enum`, `type`, or `trait` definitions",
1699 let kind = ty::GenericParamDefKind::Type {
1700 has_default: default.is_some(),
1701 object_lifetime_default: object_lifetime_defaults
1703 .map_or(rl::Set1::Empty, |o| o[i]),
1707 let param_def = ty::GenericParamDef {
1708 index: type_start + i as u32,
1709 name: param.name.ident().name,
1710 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1711 pure_wrt_drop: param.pure_wrt_drop,
1717 GenericParamKind::Const { default, .. } => {
1718 if !allow_defaults && default.is_some() {
1721 "defaults for const parameters are only allowed in \
1722 `struct`, `enum`, `type`, or `trait` definitions",
1726 let param_def = ty::GenericParamDef {
1727 index: type_start + i as u32,
1728 name: param.name.ident().name,
1729 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1730 pure_wrt_drop: param.pure_wrt_drop,
1731 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1738 // provide junk type parameter defs - the only place that
1739 // cares about anything but the length is instantiation,
1740 // and we don't do that for closures.
1741 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1742 let dummy_args = if gen.is_some() {
1743 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1745 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1748 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1749 index: type_start + i as u32,
1750 name: Symbol::intern(arg),
1752 pure_wrt_drop: false,
1753 kind: ty::GenericParamDefKind::Type {
1755 object_lifetime_default: rl::Set1::Empty,
1761 // provide junk type parameter defs for const blocks.
1762 if let Node::AnonConst(_) = node {
1763 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1764 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1765 params.push(ty::GenericParamDef {
1767 name: Symbol::intern("<const_ty>"),
1769 pure_wrt_drop: false,
1770 kind: ty::GenericParamDefKind::Type {
1772 object_lifetime_default: rl::Set1::Empty,
1779 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1782 parent: parent_def_id,
1785 param_def_id_to_index,
1786 has_self: has_self || parent_has_self,
1787 has_late_bound_regions: has_late_bound_regions(tcx, node),
1791 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1792 generic_args.iter().any(|arg| match arg {
1793 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1794 hir::GenericArg::Infer(_) => true,
1799 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1800 /// use inference to provide suggestions for the appropriate type if possible.
1801 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1806 Slice(ty) => is_suggestable_infer_ty(ty),
1807 Array(ty, length) => {
1808 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1810 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1811 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1812 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1813 Path(hir::QPath::TypeRelative(ty, segment)) => {
1814 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1816 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1817 ty_opt.map_or(false, is_suggestable_infer_ty)
1818 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1824 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1825 if let hir::FnRetTy::Return(ty) = output {
1826 if is_suggestable_infer_ty(ty) {
1833 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1834 use rustc_hir::Node::*;
1837 let def_id = def_id.expect_local();
1838 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1840 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1842 match tcx.hir().get(hir_id) {
1843 TraitItem(hir::TraitItem {
1844 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1848 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => {
1849 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1852 ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => {
1853 // Do not try to inference the return type for a impl method coming from a trait
1854 if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) =
1855 tcx.hir().get(tcx.hir().get_parent_node(hir_id))
1856 && i.of_trait.is_some()
1858 <dyn AstConv<'_>>::ty_of_fn(
1861 sig.header.unsafety,
1868 infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
1872 TraitItem(hir::TraitItem {
1873 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1876 }) => <dyn AstConv<'_>>::ty_of_fn(
1886 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
1887 let abi = tcx.hir().get_foreign_abi(hir_id);
1888 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi)
1891 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1892 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1894 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1895 ty::Binder::dummy(tcx.mk_fn_sig(
1899 hir::Unsafety::Normal,
1904 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1905 // Closure signatures are not like other function
1906 // signatures and cannot be accessed through `fn_sig`. For
1907 // example, a closure signature excludes the `self`
1908 // argument. In any case they are embedded within the
1909 // closure type as part of the `ClosureSubsts`.
1911 // To get the signature of a closure, you should use the
1912 // `sig` method on the `ClosureSubsts`:
1914 // substs.as_closure().sig(def_id, tcx)
1916 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1921 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1926 fn infer_return_ty_for_fn_sig<'tcx>(
1928 sig: &hir::FnSig<'_>,
1929 generics: &hir::Generics<'_>,
1931 icx: &ItemCtxt<'tcx>,
1932 ) -> ty::PolyFnSig<'tcx> {
1933 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1935 match get_infer_ret_ty(&sig.decl.output) {
1937 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1938 // Typeck doesn't expect erased regions to be returned from `type_of`.
1939 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match *r {
1940 ty::ReErased => tcx.lifetimes.re_static,
1943 let fn_sig = ty::Binder::dummy(fn_sig);
1945 let mut visitor = HirPlaceholderCollector::default();
1946 visitor.visit_ty(ty);
1947 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1948 let ret_ty = fn_sig.skip_binder().output();
1949 if ret_ty.is_suggestable(tcx) {
1950 diag.span_suggestion(
1952 "replace with the correct return type",
1954 Applicability::MachineApplicable,
1956 } else if matches!(ret_ty.kind(), ty::FnDef(..)) {
1957 let fn_sig = ret_ty.fn_sig(tcx);
1958 if fn_sig.skip_binder().inputs_and_output.iter().all(|t| t.is_suggestable(tcx)) {
1959 diag.span_suggestion(
1961 "replace with the correct return type",
1963 Applicability::MachineApplicable,
1966 } else if ret_ty.is_closure() {
1967 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1968 // to prevent the user from getting a papercut while trying to use the unique closure
1969 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1970 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1971 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1977 None => <dyn AstConv<'_>>::ty_of_fn(
1980 sig.header.unsafety,
1989 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1990 let icx = ItemCtxt::new(tcx, def_id);
1991 match tcx.hir().expect_item(def_id.expect_local()).kind {
1992 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1993 let selfty = tcx.type_of(def_id);
1994 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
2000 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
2001 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
2002 let item = tcx.hir().expect_item(def_id.expect_local());
2004 hir::ItemKind::Impl(hir::Impl {
2005 polarity: hir::ImplPolarity::Negative(span),
2009 if is_rustc_reservation {
2010 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
2011 tcx.sess.span_err(span, "reservation impls can't be negative");
2013 ty::ImplPolarity::Negative
2015 hir::ItemKind::Impl(hir::Impl {
2016 polarity: hir::ImplPolarity::Positive,
2020 if is_rustc_reservation {
2021 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2023 ty::ImplPolarity::Positive
2025 hir::ItemKind::Impl(hir::Impl {
2026 polarity: hir::ImplPolarity::Positive,
2030 if is_rustc_reservation {
2031 ty::ImplPolarity::Reservation
2033 ty::ImplPolarity::Positive
2036 item => bug!("impl_polarity: {:?} not an impl", item),
2040 /// Returns the early-bound lifetimes declared in this generics
2041 /// listing. For anything other than fns/methods, this is just all
2042 /// the lifetimes that are declared. For fns or methods, we have to
2043 /// screen out those that do not appear in any where-clauses etc using
2044 /// `resolve_lifetime::early_bound_lifetimes`.
2045 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2048 generics: &'a hir::Generics<'a>,
2049 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2050 let late_bound_map = if generics.params.is_empty() {
2051 // This function may be called on `def_id == CRATE_DEF_ID`,
2052 // which makes `is_late_bound_map` ICE. Don't even try if there
2053 // is no generic parameter.
2056 tcx.is_late_bound_map(def_id)
2058 let is_late_bound = move |hir_id| {
2059 let id = tcx.hir().local_def_id(hir_id);
2060 late_bound_map.map_or(false, |(_, set)| set.contains(&id))
2062 generics.params.iter().filter(move |param| match param.kind {
2063 GenericParamKind::Lifetime { .. } => !is_late_bound(param.hir_id),
2068 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2069 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2070 /// inferred constraints concerning which regions outlive other regions.
2071 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2072 debug!("predicates_defined_on({:?})", def_id);
2073 let mut result = tcx.explicit_predicates_of(def_id);
2074 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2075 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2076 if !inferred_outlives.is_empty() {
2078 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2079 def_id, inferred_outlives,
2081 if result.predicates.is_empty() {
2082 result.predicates = inferred_outlives;
2084 result.predicates = tcx
2086 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2090 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2094 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2095 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2096 /// `Self: Trait` predicates for traits.
2097 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2098 let mut result = tcx.predicates_defined_on(def_id);
2100 if tcx.is_trait(def_id) {
2101 // For traits, add `Self: Trait` predicate. This is
2102 // not part of the predicates that a user writes, but it
2103 // is something that one must prove in order to invoke a
2104 // method or project an associated type.
2106 // In the chalk setup, this predicate is not part of the
2107 // "predicates" for a trait item. But it is useful in
2108 // rustc because if you directly (e.g.) invoke a trait
2109 // method like `Trait::method(...)`, you must naturally
2110 // prove that the trait applies to the types that were
2111 // used, and adding the predicate into this list ensures
2112 // that this is done.
2114 // We use a DUMMY_SP here as a way to signal trait bounds that come
2115 // from the trait itself that *shouldn't* be shown as the source of
2116 // an obligation and instead be skipped. Otherwise we'd use
2117 // `tcx.def_span(def_id);`
2118 let span = rustc_span::DUMMY_SP;
2120 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2121 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2125 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2129 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2130 /// N.B., this does not include any implied/inferred constraints.
2131 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2134 debug!("explicit_predicates_of(def_id={:?})", def_id);
2136 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2137 let node = tcx.hir().get(hir_id);
2139 let mut is_trait = None;
2140 let mut is_default_impl_trait = None;
2142 let icx = ItemCtxt::new(tcx, def_id);
2144 const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
2146 // We use an `IndexSet` to preserves order of insertion.
2147 // Preserving the order of insertion is important here so as not to break UI tests.
2148 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2150 let ast_generics = match node {
2151 Node::TraitItem(item) => item.generics,
2153 Node::ImplItem(item) => item.generics,
2155 Node::Item(item) => {
2157 ItemKind::Impl(ref impl_) => {
2158 if impl_.defaultness.is_default() {
2159 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2163 ItemKind::Fn(.., ref generics, _)
2164 | ItemKind::TyAlias(_, ref generics)
2165 | ItemKind::Enum(_, ref generics)
2166 | ItemKind::Struct(_, ref generics)
2167 | ItemKind::Union(_, ref generics) => *generics,
2169 ItemKind::Trait(_, _, ref generics, ..) => {
2170 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2173 ItemKind::TraitAlias(ref generics, _) => {
2174 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2177 ItemKind::OpaqueTy(OpaqueTy {
2178 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2181 // return-position impl trait
2183 // We don't inherit predicates from the parent here:
2184 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2185 // then the return type is `f::<'static, T>::{{opaque}}`.
2187 // If we inherited the predicates of `f` then we would
2188 // require that `T: 'static` to show that the return
2189 // type is well-formed.
2191 // The only way to have something with this opaque type
2192 // is from the return type of the containing function,
2193 // which will ensure that the function's predicates
2195 return ty::GenericPredicates { parent: None, predicates: &[] };
2197 ItemKind::OpaqueTy(OpaqueTy {
2199 origin: hir::OpaqueTyOrigin::TyAlias,
2202 // type-alias impl trait
2210 Node::ForeignItem(item) => match item.kind {
2211 ForeignItemKind::Static(..) => NO_GENERICS,
2212 ForeignItemKind::Fn(_, _, ref generics) => *generics,
2213 ForeignItemKind::Type => NO_GENERICS,
2219 let generics = tcx.generics_of(def_id);
2220 let parent_count = generics.parent_count as u32;
2221 let has_own_self = generics.has_self && parent_count == 0;
2223 // Below we'll consider the bounds on the type parameters (including `Self`)
2224 // and the explicit where-clauses, but to get the full set of predicates
2225 // on a trait we need to add in the supertrait bounds and bounds found on
2226 // associated types.
2227 if let Some(_trait_ref) = is_trait {
2228 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2231 // In default impls, we can assume that the self type implements
2232 // the trait. So in:
2234 // default impl Foo for Bar { .. }
2236 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2237 // (see below). Recall that a default impl is not itself an impl, but rather a
2238 // set of defaults that can be incorporated into another impl.
2239 if let Some(trait_ref) = is_default_impl_trait {
2240 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2243 // Collect the region predicates that were declared inline as
2244 // well. In the case of parameters declared on a fn or method, we
2245 // have to be careful to only iterate over early-bound regions.
2246 let mut index = parent_count
2247 + has_own_self as u32
2248 + early_bound_lifetimes_from_generics(tcx, hir_id.owner, ast_generics).count() as u32;
2250 // Collect the predicates that were written inline by the user on each
2251 // type parameter (e.g., `<T: Foo>`).
2252 for param in ast_generics.params {
2254 // We already dealt with early bound lifetimes above.
2255 GenericParamKind::Lifetime { .. } => (),
2256 GenericParamKind::Type { .. } => {
2257 let name = param.name.ident().name;
2258 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2261 let mut bounds = Bounds::default();
2262 // Params are implicitly sized unless a `?Sized` bound is found
2263 <dyn AstConv<'_>>::add_implicitly_sized(
2267 Some((param.hir_id, ast_generics.predicates)),
2270 predicates.extend(bounds.predicates(tcx, param_ty));
2272 GenericParamKind::Const { .. } => {
2273 // Bounds on const parameters are currently not possible.
2279 // Add in the bounds that appear in the where-clause.
2280 for predicate in ast_generics.predicates {
2282 hir::WherePredicate::BoundPredicate(bound_pred) => {
2283 let ty = icx.to_ty(bound_pred.bounded_ty);
2284 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2286 // Keep the type around in a dummy predicate, in case of no bounds.
2287 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2288 // is still checked for WF.
2289 if bound_pred.bounds.is_empty() {
2290 if let ty::Param(_) = ty.kind() {
2291 // This is a `where T:`, which can be in the HIR from the
2292 // transformation that moves `?Sized` to `T`'s declaration.
2293 // We can skip the predicate because type parameters are
2294 // trivially WF, but also we *should*, to avoid exposing
2295 // users who never wrote `where Type:,` themselves, to
2296 // compiler/tooling bugs from not handling WF predicates.
2298 let span = bound_pred.bounded_ty.span;
2299 let re_root_empty = tcx.lifetimes.re_root_empty;
2300 let predicate = ty::Binder::bind_with_vars(
2301 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2307 predicates.insert((predicate.to_predicate(tcx), span));
2311 let mut bounds = Bounds::default();
2312 <dyn AstConv<'_>>::add_bounds(
2315 bound_pred.bounds.iter(),
2319 predicates.extend(bounds.predicates(tcx, ty));
2322 hir::WherePredicate::RegionPredicate(region_pred) => {
2323 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2324 predicates.extend(region_pred.bounds.iter().map(|bound| {
2325 let (r2, span) = match bound {
2326 hir::GenericBound::Outlives(lt) => {
2327 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2331 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2332 ty::OutlivesPredicate(r1, r2),
2334 .to_predicate(icx.tcx);
2340 hir::WherePredicate::EqPredicate(..) => {
2346 if tcx.features().generic_const_exprs {
2347 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2350 let mut predicates: Vec<_> = predicates.into_iter().collect();
2352 // Subtle: before we store the predicates into the tcx, we
2353 // sort them so that predicates like `T: Foo<Item=U>` come
2354 // before uses of `U`. This avoids false ambiguity errors
2355 // in trait checking. See `setup_constraining_predicates`
2357 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2358 let self_ty = tcx.type_of(def_id);
2359 let trait_ref = tcx.impl_trait_ref(def_id);
2360 cgp::setup_constraining_predicates(
2364 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2368 let result = ty::GenericPredicates {
2369 parent: generics.parent,
2370 predicates: tcx.arena.alloc_from_iter(predicates),
2372 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2376 fn const_evaluatable_predicates_of<'tcx>(
2379 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2380 struct ConstCollector<'tcx> {
2382 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2385 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2386 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2387 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2388 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2389 if let ty::ConstKind::Unevaluated(uv) = ct.val() {
2390 assert_eq!(uv.promoted, None);
2391 let span = self.tcx.hir().span(c.hir_id);
2393 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2394 .to_predicate(self.tcx),
2400 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2401 // Do not look into const param defaults,
2402 // these get checked when they are actually instantiated.
2404 // We do not want the following to error:
2406 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2407 // struct Bar<const N: usize>(Foo<N, 3>);
2411 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2412 let node = tcx.hir().get(hir_id);
2414 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2415 if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
2416 if let Some(of_trait) = &impl_.of_trait {
2417 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2418 collector.visit_trait_ref(of_trait);
2421 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2422 collector.visit_ty(impl_.self_ty);
2425 if let Some(generics) = node.generics() {
2426 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2427 collector.visit_generics(generics);
2430 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2431 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2432 collector.visit_fn_decl(fn_sig.decl);
2434 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2439 fn trait_explicit_predicates_and_bounds(
2442 ) -> ty::GenericPredicates<'_> {
2443 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2444 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2447 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2448 let def_kind = tcx.def_kind(def_id);
2449 if let DefKind::Trait = def_kind {
2450 // Remove bounds on associated types from the predicates, they will be
2451 // returned by `explicit_item_bounds`.
2452 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2453 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2455 let is_assoc_item_ty = |ty: Ty<'_>| {
2456 // For a predicate from a where clause to become a bound on an
2458 // * It must use the identity substs of the item.
2459 // * Since any generic parameters on the item are not in scope,
2460 // this means that the item is not a GAT, and its identity
2461 // substs are the same as the trait's.
2462 // * It must be an associated type for this trait (*not* a
2464 if let ty::Projection(projection) = ty.kind() {
2465 projection.substs == trait_identity_substs
2466 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2472 let predicates: Vec<_> = predicates_and_bounds
2476 .filter(|(pred, _)| match pred.kind().skip_binder() {
2477 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2478 ty::PredicateKind::Projection(proj) => {
2479 !is_assoc_item_ty(proj.projection_ty.self_ty())
2481 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2485 if predicates.len() == predicates_and_bounds.predicates.len() {
2486 predicates_and_bounds
2488 ty::GenericPredicates {
2489 parent: predicates_and_bounds.parent,
2490 predicates: tcx.arena.alloc_slice(&predicates),
2494 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2495 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2496 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2497 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2498 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2499 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2501 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2502 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2503 // ^^^ explicit_predicates_of on
2504 // parent item we dont have set as the
2505 // parent of generics returned by `generics_of`
2507 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2508 let item_def_id = tcx.hir().get_parent_item(hir_id);
2509 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2510 return tcx.explicit_predicates_of(item_def_id);
2513 gather_explicit_predicates_of(tcx, def_id)
2517 /// Converts a specific `GenericBound` from the AST into a set of
2518 /// predicates that apply to the self type. A vector is returned
2519 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2520 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2521 /// and `<T as Bar>::X == i32`).
2522 fn predicates_from_bound<'tcx>(
2523 astconv: &dyn AstConv<'tcx>,
2525 bound: &'tcx hir::GenericBound<'tcx>,
2526 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2527 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2528 let mut bounds = Bounds::default();
2529 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2530 bounds.predicates(astconv.tcx(), param_ty).collect()
2533 fn compute_sig_of_foreign_fn_decl<'tcx>(
2536 decl: &'tcx hir::FnDecl<'tcx>,
2538 ) -> ty::PolyFnSig<'tcx> {
2539 let unsafety = if abi == abi::Abi::RustIntrinsic {
2540 intrinsic_operation_unsafety(tcx.item_name(def_id))
2542 hir::Unsafety::Unsafe
2544 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2545 let fty = <dyn AstConv<'_>>::ty_of_fn(
2546 &ItemCtxt::new(tcx, def_id),
2555 // Feature gate SIMD types in FFI, since I am not sure that the
2556 // ABIs are handled at all correctly. -huonw
2557 if abi != abi::Abi::RustIntrinsic
2558 && abi != abi::Abi::PlatformIntrinsic
2559 && !tcx.features().simd_ffi
2561 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2566 .span_to_snippet(ast_ty.span)
2567 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2572 "use of SIMD type{} in FFI is highly experimental and \
2573 may result in invalid code",
2577 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2581 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2584 if let hir::FnRetTy::Return(ref ty) = decl.output {
2585 check(ty, fty.output().skip_binder())
2592 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2593 match tcx.hir().get_if_local(def_id) {
2594 Some(Node::ForeignItem(..)) => true,
2596 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2600 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2601 match tcx.hir().get_if_local(def_id) {
2602 Some(Node::Expr(&rustc_hir::Expr {
2603 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2605 })) => tcx.hir().body(body_id).generator_kind(),
2607 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2611 fn from_target_feature(
2614 attr: &ast::Attribute,
2615 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2616 target_features: &mut Vec<Symbol>,
2618 let Some(list) = attr.meta_item_list() else { return };
2619 let bad_item = |span| {
2620 let msg = "malformed `target_feature` attribute input";
2621 let code = "enable = \"..\"".to_owned();
2623 .struct_span_err(span, msg)
2624 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2627 let rust_features = tcx.features();
2629 // Only `enable = ...` is accepted in the meta-item list.
2630 if !item.has_name(sym::enable) {
2631 bad_item(item.span());
2635 // Must be of the form `enable = "..."` (a string).
2636 let Some(value) = item.value_str() else {
2637 bad_item(item.span());
2641 // We allow comma separation to enable multiple features.
2642 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2643 let Some(feature_gate) = supported_target_features.get(feature) else {
2645 format!("the feature named `{}` is not valid for this target", feature);
2646 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2649 format!("`{}` is not valid for this target", feature),
2651 if let Some(stripped) = feature.strip_prefix('+') {
2652 let valid = supported_target_features.contains_key(stripped);
2654 err.help("consider removing the leading `+` in the feature name");
2661 // Only allow features whose feature gates have been enabled.
2662 let allowed = match feature_gate.as_ref().copied() {
2663 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2664 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2665 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2666 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2667 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2668 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2669 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2670 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2671 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2672 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2673 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2674 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2675 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2676 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2677 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2678 Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
2679 Some(name) => bug!("unknown target feature gate {}", name),
2682 if !allowed && id.is_local() {
2684 &tcx.sess.parse_sess,
2685 feature_gate.unwrap(),
2687 &format!("the target feature `{}` is currently unstable", feature),
2691 Some(Symbol::intern(feature))
2696 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2697 use rustc_middle::mir::mono::Linkage::*;
2699 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2700 // applicable to variable declarations and may not really make sense for
2701 // Rust code in the first place but allow them anyway and trust that the
2702 // user knows what they're doing. Who knows, unanticipated use cases may pop
2703 // up in the future.
2705 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2706 // and don't have to be, LLVM treats them as no-ops.
2708 "appending" => Appending,
2709 "available_externally" => AvailableExternally,
2711 "extern_weak" => ExternalWeak,
2712 "external" => External,
2713 "internal" => Internal,
2714 "linkonce" => LinkOnceAny,
2715 "linkonce_odr" => LinkOnceODR,
2716 "private" => Private,
2718 "weak_odr" => WeakODR,
2720 let span = tcx.hir().span_if_local(def_id);
2721 if let Some(span) = span {
2722 tcx.sess.span_fatal(span, "invalid linkage specified")
2724 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2730 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2731 let attrs = tcx.get_attrs(id);
2733 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2734 if tcx.should_inherit_track_caller(id) {
2735 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2738 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2739 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2740 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2741 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2745 // The panic_no_unwind function called by TerminatorKind::Abort will never
2746 // unwind. If the panic handler that it invokes unwind then it will simply
2747 // call the panic handler again.
2748 if Some(id) == tcx.lang_items().panic_no_unwind() {
2749 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2752 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2754 let mut inline_span = None;
2755 let mut link_ordinal_span = None;
2756 let mut no_sanitize_span = None;
2757 for attr in attrs.iter() {
2758 if attr.has_name(sym::cold) {
2759 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2760 } else if attr.has_name(sym::rustc_allocator) {
2761 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2762 } else if attr.has_name(sym::ffi_returns_twice) {
2763 if tcx.is_foreign_item(id) {
2764 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2766 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2771 "`#[ffi_returns_twice]` may only be used on foreign functions"
2775 } else if attr.has_name(sym::ffi_pure) {
2776 if tcx.is_foreign_item(id) {
2777 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2778 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2783 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2787 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2790 // `#[ffi_pure]` is only allowed on foreign functions
2795 "`#[ffi_pure]` may only be used on foreign functions"
2799 } else if attr.has_name(sym::ffi_const) {
2800 if tcx.is_foreign_item(id) {
2801 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2803 // `#[ffi_const]` is only allowed on foreign functions
2808 "`#[ffi_const]` may only be used on foreign functions"
2812 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2813 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2814 } else if attr.has_name(sym::naked) {
2815 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2816 } else if attr.has_name(sym::no_mangle) {
2817 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2818 } else if attr.has_name(sym::no_coverage) {
2819 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2820 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2821 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2822 } else if attr.has_name(sym::used) {
2823 let inner = attr.meta_item_list();
2824 match inner.as_deref() {
2825 Some([item]) if item.has_name(sym::linker) => {
2826 if !tcx.features().used_with_arg {
2828 &tcx.sess.parse_sess,
2831 "`#[used(linker)]` is currently unstable",
2835 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2837 Some([item]) if item.has_name(sym::compiler) => {
2838 if !tcx.features().used_with_arg {
2840 &tcx.sess.parse_sess,
2843 "`#[used(compiler)]` is currently unstable",
2847 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2853 "expected `used`, `used(compiler)` or `used(linker)`",
2857 None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
2859 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2860 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2865 "`#[cmse_nonsecure_entry]` requires C ABI"
2869 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2870 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2873 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2874 } else if attr.has_name(sym::thread_local) {
2875 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2876 } else if attr.has_name(sym::track_caller) {
2877 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2878 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2881 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2883 &tcx.sess.parse_sess,
2884 sym::closure_track_caller,
2886 "`#[track_caller]` on closures is currently unstable",
2890 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2891 } else if attr.has_name(sym::export_name) {
2892 if let Some(s) = attr.value_str() {
2893 if s.as_str().contains('\0') {
2894 // `#[export_name = ...]` will be converted to a null-terminated string,
2895 // so it may not contain any null characters.
2900 "`export_name` may not contain null characters"
2904 codegen_fn_attrs.export_name = Some(s);
2906 } else if attr.has_name(sym::target_feature) {
2907 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2908 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2909 // The `#[target_feature]` attribute is allowed on
2910 // WebAssembly targets on all functions, including safe
2911 // ones. Other targets require that `#[target_feature]` is
2912 // only applied to unsafe functions (pending the
2913 // `target_feature_11` feature) because on most targets
2914 // execution of instructions that are not supported is
2915 // considered undefined behavior. For WebAssembly which is a
2916 // 100% safe target at execution time it's not possible to
2917 // execute undefined instructions, and even if a future
2918 // feature was added in some form for this it would be a
2919 // deterministic trap. There is no undefined behavior when
2920 // executing WebAssembly so `#[target_feature]` is allowed
2921 // on safe functions (but again, only for WebAssembly)
2923 // Note that this is also allowed if `actually_rustdoc` so
2924 // if a target is documenting some wasm-specific code then
2925 // it's not spuriously denied.
2926 } else if !tcx.features().target_feature_11 {
2927 let mut err = feature_err(
2928 &tcx.sess.parse_sess,
2929 sym::target_feature_11,
2931 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2933 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2935 } else if let Some(local_id) = id.as_local() {
2936 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2939 from_target_feature(
2943 supported_target_features,
2944 &mut codegen_fn_attrs.target_features,
2946 } else if attr.has_name(sym::linkage) {
2947 if let Some(val) = attr.value_str() {
2948 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, val.as_str()));
2950 } else if attr.has_name(sym::link_section) {
2951 if let Some(val) = attr.value_str() {
2952 if val.as_str().bytes().any(|b| b == 0) {
2954 "illegal null byte in link_section \
2958 tcx.sess.span_err(attr.span, &msg);
2960 codegen_fn_attrs.link_section = Some(val);
2963 } else if attr.has_name(sym::link_name) {
2964 codegen_fn_attrs.link_name = attr.value_str();
2965 } else if attr.has_name(sym::link_ordinal) {
2966 link_ordinal_span = Some(attr.span);
2967 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2968 codegen_fn_attrs.link_ordinal = ordinal;
2970 } else if attr.has_name(sym::no_sanitize) {
2971 no_sanitize_span = Some(attr.span);
2972 if let Some(list) = attr.meta_item_list() {
2973 for item in list.iter() {
2974 if item.has_name(sym::address) {
2975 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2976 } else if item.has_name(sym::cfi) {
2977 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2978 } else if item.has_name(sym::memory) {
2979 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2980 } else if item.has_name(sym::memtag) {
2981 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
2982 } else if item.has_name(sym::thread) {
2983 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2984 } else if item.has_name(sym::hwaddress) {
2985 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2988 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2989 .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, or `thread`")
2994 } else if attr.has_name(sym::instruction_set) {
2995 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
2996 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
2997 [NestedMetaItem::MetaItem(set)] => {
2999 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
3000 match segments.as_slice() {
3001 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3002 if !tcx.sess.target.has_thumb_interworking {
3004 tcx.sess.diagnostic(),
3007 "target does not support `#[instruction_set]`"
3011 } else if segments[1] == sym::a32 {
3012 Some(InstructionSetAttr::ArmA32)
3013 } else if segments[1] == sym::t32 {
3014 Some(InstructionSetAttr::ArmT32)
3021 tcx.sess.diagnostic(),
3024 "invalid instruction set specified",
3033 tcx.sess.diagnostic(),
3036 "`#[instruction_set]` requires an argument"
3043 tcx.sess.diagnostic(),
3046 "cannot specify more than one instruction set"
3054 tcx.sess.diagnostic(),
3057 "must specify an instruction set"
3063 } else if attr.has_name(sym::repr) {
3064 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3065 Some(items) => match items.as_slice() {
3066 [item] => match item.name_value_literal() {
3067 Some((sym::align, literal)) => {
3068 let alignment = rustc_attr::parse_alignment(&literal.kind);
3071 Ok(align) => Some(align),
3074 tcx.sess.diagnostic(),
3077 "invalid `repr(align)` attribute: {}",
3096 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3097 if !attr.has_name(sym::inline) {
3100 match attr.meta_kind() {
3101 Some(MetaItemKind::Word) => InlineAttr::Hint,
3102 Some(MetaItemKind::List(ref items)) => {
3103 inline_span = Some(attr.span);
3104 if items.len() != 1 {
3106 tcx.sess.diagnostic(),
3109 "expected one argument"
3113 } else if list_contains_name(&items, sym::always) {
3115 } else if list_contains_name(&items, sym::never) {
3119 tcx.sess.diagnostic(),
3129 Some(MetaItemKind::NameValue(_)) => ia,
3134 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3135 if !attr.has_name(sym::optimize) {
3138 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3139 match attr.meta_kind() {
3140 Some(MetaItemKind::Word) => {
3141 err(attr.span, "expected one argument");
3144 Some(MetaItemKind::List(ref items)) => {
3145 inline_span = Some(attr.span);
3146 if items.len() != 1 {
3147 err(attr.span, "expected one argument");
3149 } else if list_contains_name(&items, sym::size) {
3151 } else if list_contains_name(&items, sym::speed) {
3154 err(items[0].span(), "invalid argument");
3158 Some(MetaItemKind::NameValue(_)) => ia,
3163 // #73631: closures inherit `#[target_feature]` annotations
3164 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3165 let owner_id = tcx.parent(id).expect("closure should have a parent");
3168 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3171 // If a function uses #[target_feature] it can't be inlined into general
3172 // purpose functions as they wouldn't have the right target features
3173 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3175 if !codegen_fn_attrs.target_features.is_empty() {
3176 if codegen_fn_attrs.inline == InlineAttr::Always {
3177 if let Some(span) = inline_span {
3180 "cannot use `#[inline(always)]` with \
3181 `#[target_feature]`",
3187 if !codegen_fn_attrs.no_sanitize.is_empty() {
3188 if codegen_fn_attrs.inline == InlineAttr::Always {
3189 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3190 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3191 tcx.struct_span_lint_hir(
3192 lint::builtin::INLINE_NO_SANITIZE,
3196 lint.build("`no_sanitize` will have no effect after inlining")
3197 .span_note(inline_span, "inlining requested here")
3205 // Weak lang items have the same semantics as "std internal" symbols in the
3206 // sense that they're preserved through all our LTO passes and only
3207 // strippable by the linker.
3209 // Additionally weak lang items have predetermined symbol names.
3210 if tcx.is_weak_lang_item(id) {
3211 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3213 if let Some(name) = weak_lang_items::link_name(attrs) {
3214 codegen_fn_attrs.export_name = Some(name);
3215 codegen_fn_attrs.link_name = Some(name);
3217 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3219 // Internal symbols to the standard library all have no_mangle semantics in
3220 // that they have defined symbol names present in the function name. This
3221 // also applies to weak symbols where they all have known symbol names.
3222 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3223 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3226 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3227 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3228 // intrinsic functions.
3229 if let Some(name) = &codegen_fn_attrs.link_name {
3230 if name.as_str().starts_with("llvm.") {
3231 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3238 /// Computes the set of target features used in a function for the purposes of
3239 /// inline assembly.
3240 fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, id: DefId) -> &'tcx FxHashSet<Symbol> {
3241 let mut target_features = tcx.sess.target_features.clone();
3242 let attrs = tcx.codegen_fn_attrs(id);
3243 target_features.extend(&attrs.target_features);
3244 match attrs.instruction_set {
3246 Some(InstructionSetAttr::ArmA32) => {
3247 target_features.remove(&sym::thumb_mode);
3249 Some(InstructionSetAttr::ArmT32) => {
3250 target_features.insert(sym::thumb_mode);
3253 tcx.arena.alloc(target_features)
3256 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3257 /// applied to the method prototype.
3258 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3259 if let Some(impl_item) = tcx.opt_associated_item(def_id)
3260 && let ty::AssocItemContainer::ImplContainer(_) = impl_item.container
3261 && let Some(trait_item) = impl_item.trait_item_def_id
3264 .codegen_fn_attrs(trait_item)
3266 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3272 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3273 use rustc_ast::{Lit, LitIntType, LitKind};
3274 let meta_item_list = attr.meta_item_list();
3275 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3276 let sole_meta_list = match meta_item_list {
3277 Some([item]) => item.literal(),
3280 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3281 .note("the attribute requires exactly one argument")
3287 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3288 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3289 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3290 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3291 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3293 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3294 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3295 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3296 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3297 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3298 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3299 // about LINK.EXE failing.)
3300 if *ordinal <= u16::MAX as u128 {
3301 Some(*ordinal as u16)
3303 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3305 .struct_span_err(attr.span, &msg)
3306 .note("the value may not exceed `u16::MAX`")
3312 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3313 .note("an unsuffixed integer value, e.g., `1`, is expected")
3319 fn check_link_name_xor_ordinal(
3321 codegen_fn_attrs: &CodegenFnAttrs,
3322 inline_span: Option<Span>,
3324 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3327 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3328 if let Some(span) = inline_span {
3329 tcx.sess.span_err(span, msg);
3335 /// Checks the function annotated with `#[target_feature]` is not a safe
3336 /// trait method implementation, reporting an error if it is.
3337 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3338 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3339 let node = tcx.hir().get(hir_id);
3340 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3341 let parent_id = tcx.hir().get_parent_item(hir_id);
3342 let parent_item = tcx.hir().expect_item(parent_id);
3343 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3347 "`#[target_feature(..)]` cannot be applied to safe trait method",
3349 .span_label(attr_span, "cannot be applied to safe trait method")
3350 .span_label(tcx.def_span(id), "not an `unsafe` function")