1 // ignore-tidy-filelength
2 //! "Collection" is the process of determining the type and other external
3 //! details of each item in Rust. Collection is specifically concerned
4 //! with *inter-procedural* things -- for example, for a function
5 //! definition, collection will figure out the type and signature of the
6 //! function, but it will not visit the *body* of the function in any way,
7 //! nor examine type annotations on local variables (that's the job of
10 //! Collecting is ultimately defined by a bundle of queries that
11 //! inquire after various facts about the items in the crate (e.g.,
12 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
15 //! At present, however, we do run collection across all items in the
16 //! crate as a kind of pass. This should eventually be factored away.
18 use crate::astconv::AstConv;
19 use crate::bounds::Bounds;
20 use crate::check::intrinsic::intrinsic_operation_unsafety;
21 use crate::constrained_generic_params as cgp;
23 use crate::middle::resolve_lifetime as rl;
25 use rustc_ast::{MetaItemKind, NestedMetaItem};
26 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
27 use rustc_data_structures::captures::Captures;
28 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
29 use rustc_errors::{struct_span_err, Applicability};
31 use rustc_hir::def::{CtorKind, DefKind};
32 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
33 use rustc_hir::intravisit::{self, Visitor};
34 use rustc_hir::weak_lang_items;
35 use rustc_hir::{GenericParamKind, HirId, Node};
36 use rustc_middle::hir::nested_filter;
37 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
38 use rustc_middle::mir::mono::Linkage;
39 use rustc_middle::ty::query::Providers;
40 use rustc_middle::ty::subst::InternalSubsts;
41 use rustc_middle::ty::util::Discr;
42 use rustc_middle::ty::util::IntTypeExt;
43 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
44 use rustc_middle::ty::{ReprOptions, ToPredicate, TypeFoldable};
45 use rustc_session::lint;
46 use rustc_session::parse::feature_err;
47 use rustc_span::symbol::{kw, sym, Ident, Symbol};
48 use rustc_span::{Span, DUMMY_SP};
49 use rustc_target::spec::{abi, PanicStrategy, SanitizerSet};
50 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
56 struct OnlySelfBounds(bool);
58 ///////////////////////////////////////////////////////////////////////////
61 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
62 tcx.hir().visit_item_likes_in_module(
64 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
68 pub fn provide(providers: &mut Providers) {
69 *providers = Providers {
70 opt_const_param_of: type_of::opt_const_param_of,
71 type_of: type_of::type_of,
72 item_bounds: item_bounds::item_bounds,
73 explicit_item_bounds: item_bounds::explicit_item_bounds,
76 predicates_defined_on,
77 explicit_predicates_of,
79 super_predicates_that_define_assoc_type,
80 trait_explicit_predicates_and_bounds,
81 type_param_predicates,
91 collect_mod_item_types,
92 should_inherit_track_caller,
97 ///////////////////////////////////////////////////////////////////////////
99 /// Context specific to some particular item. This is what implements
100 /// `AstConv`. It has information about the predicates that are defined
101 /// on the trait. Unfortunately, this predicate information is
102 /// available in various different forms at various points in the
103 /// process. So we can't just store a pointer to e.g., the AST or the
104 /// parsed ty form, we have to be more flexible. To this end, the
105 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
106 /// `get_type_parameter_bounds` requests, drawing the information from
107 /// the AST (`hir::Generics`), recursively.
108 pub struct ItemCtxt<'tcx> {
113 ///////////////////////////////////////////////////////////////////////////
116 crate struct HirPlaceholderCollector(crate Vec<Span>);
118 impl<'v> Visitor<'v> for HirPlaceholderCollector {
119 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
120 if let hir::TyKind::Infer = t.kind {
123 intravisit::walk_ty(self, t)
125 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
127 hir::GenericArg::Infer(inf) => {
128 self.0.push(inf.span);
129 intravisit::walk_inf(self, inf);
131 hir::GenericArg::Type(t) => self.visit_ty(t),
135 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
136 if let &hir::ArrayLen::Infer(_, span) = length {
139 intravisit::walk_array_len(self, length)
143 struct CollectItemTypesVisitor<'tcx> {
147 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
148 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
149 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
150 crate fn placeholder_type_error<'tcx>(
153 generics: &[hir::GenericParam<'_>],
154 placeholder_types: Vec<Span>,
156 hir_ty: Option<&hir::Ty<'_>>,
159 if placeholder_types.is_empty() {
163 let type_name = generics.next_type_param_name(None);
164 let mut sugg: Vec<_> =
165 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
167 if generics.is_empty() {
168 if let Some(span) = span {
169 sugg.push((span, format!("<{}>", type_name)));
171 } else if let Some(arg) = generics
173 .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
175 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
176 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
177 sugg.push((arg.span, (*type_name).to_string()));
179 let last = generics.iter().last().unwrap();
180 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
181 let span = last.bounds_span_for_suggestions().unwrap_or(last.span.shrink_to_hi());
182 sugg.push((span, format!(", {}", type_name)));
185 let mut err = bad_placeholder(tcx, placeholder_types, kind);
187 // Suggest, but only if it is not a function in const or static
189 let mut is_fn = false;
190 let mut is_const_or_static = false;
192 if let Some(hir_ty) = hir_ty {
193 if let hir::TyKind::BareFn(_) = hir_ty.kind {
196 // Check if parent is const or static
197 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
198 let parent_node = tcx.hir().get(parent_id);
200 is_const_or_static = matches!(
202 Node::Item(&hir::Item {
203 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
205 }) | Node::TraitItem(&hir::TraitItem {
206 kind: hir::TraitItemKind::Const(..),
208 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
213 // if function is wrapped around a const or static,
214 // then don't show the suggestion
215 if !(is_fn && is_const_or_static) {
216 err.multipart_suggestion(
217 "use type parameters instead",
219 Applicability::HasPlaceholders,
226 fn reject_placeholder_type_signatures_in_item<'tcx>(
228 item: &'tcx hir::Item<'tcx>,
230 let (generics, suggest) = match &item.kind {
231 hir::ItemKind::Union(_, generics)
232 | hir::ItemKind::Enum(_, generics)
233 | hir::ItemKind::TraitAlias(generics, _)
234 | hir::ItemKind::Trait(_, _, generics, ..)
235 | hir::ItemKind::Impl(hir::Impl { generics, .. })
236 | hir::ItemKind::Struct(_, generics) => (generics, true),
237 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
238 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
239 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
243 let mut visitor = HirPlaceholderCollector::default();
244 visitor.visit_item(item);
246 placeholder_type_error(
257 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
258 type NestedFilter = nested_filter::OnlyBodies;
260 fn nested_visit_map(&mut self) -> Self::Map {
264 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
265 convert_item(self.tcx, item.item_id());
266 reject_placeholder_type_signatures_in_item(self.tcx, item);
267 intravisit::walk_item(self, item);
270 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
271 for param in generics.params {
273 hir::GenericParamKind::Lifetime { .. } => {}
274 hir::GenericParamKind::Type { default: Some(_), .. } => {
275 let def_id = self.tcx.hir().local_def_id(param.hir_id);
276 self.tcx.ensure().type_of(def_id);
278 hir::GenericParamKind::Type { .. } => {}
279 hir::GenericParamKind::Const { default, .. } => {
280 let def_id = self.tcx.hir().local_def_id(param.hir_id);
281 self.tcx.ensure().type_of(def_id);
282 if let Some(default) = default {
283 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
284 // need to store default and type of default
285 self.tcx.ensure().type_of(default_def_id);
286 self.tcx.ensure().const_param_default(def_id);
291 intravisit::walk_generics(self, generics);
294 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
295 if let hir::ExprKind::Closure(..) = expr.kind {
296 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
297 self.tcx.ensure().generics_of(def_id);
298 // We do not call `type_of` for closures here as that
299 // depends on typecheck and would therefore hide
300 // any further errors in case one typeck fails.
302 intravisit::walk_expr(self, expr);
305 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
306 convert_trait_item(self.tcx, trait_item.trait_item_id());
307 intravisit::walk_trait_item(self, trait_item);
310 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
311 convert_impl_item(self.tcx, impl_item.impl_item_id());
312 intravisit::walk_impl_item(self, impl_item);
316 ///////////////////////////////////////////////////////////////////////////
317 // Utility types and common code for the above passes.
319 fn bad_placeholder<'tcx>(
321 mut spans: Vec<Span>,
323 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
324 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
327 let mut err = struct_span_err!(
331 "the placeholder `_` is not allowed within types on item signatures for {}",
335 err.span_label(span, "not allowed in type signatures");
340 impl<'tcx> ItemCtxt<'tcx> {
341 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
342 ItemCtxt { tcx, item_def_id }
345 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
346 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
349 pub fn hir_id(&self) -> hir::HirId {
350 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
353 pub fn node(&self) -> hir::Node<'tcx> {
354 self.tcx.hir().get(self.hir_id())
358 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
359 fn tcx(&self) -> TyCtxt<'tcx> {
363 fn item_def_id(&self) -> Option<DefId> {
364 Some(self.item_def_id)
367 fn get_type_parameter_bounds(
372 ) -> ty::GenericPredicates<'tcx> {
373 self.tcx.at(span).type_param_predicates((
375 def_id.expect_local(),
380 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
384 fn allow_ty_infer(&self) -> bool {
388 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
389 self.tcx().ty_error_with_message(span, "bad placeholder type")
395 _: Option<&ty::GenericParamDef>,
397 ) -> &'tcx 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(param_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(param_id));
573 // Don't look for bounds where the type parameter isn't in scope.
574 let parent = if item_def_id == param_owner.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 from_ty_params = ast_generics
664 .filter_map(|param| match param.kind {
665 GenericParamKind::Type { .. } | GenericParamKind::Const { .. }
666 if param.hir_id == param_id =>
672 .flat_map(|bounds| bounds.iter())
673 .filter(|b| match assoc_name {
674 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
677 .flat_map(|b| predicates_from_bound(self, ty, b, ty::List::empty()));
679 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
680 let from_where_clauses = ast_generics
684 .filter_map(|wp| match *wp {
685 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
689 let bt = if bp.is_param_bound(param_def_id) {
691 } else if !only_self_bounds.0 {
692 Some(self.to_ty(bp.bounded_ty))
696 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
700 .filter(|b| match assoc_name {
701 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
704 .filter_map(move |b| bt.map(|bt| (bt, b, bvars)))
706 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars));
708 from_ty_params.chain(from_where_clauses).collect()
711 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
712 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
715 hir::GenericBound::Trait(poly_trait_ref, _) => {
716 let trait_ref = &poly_trait_ref.trait_ref;
717 if let Some(trait_did) = trait_ref.trait_def_id() {
718 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
728 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
729 let it = tcx.hir().item(item_id);
730 debug!("convert: item {} with id {}", it.ident, it.hir_id());
731 let def_id = item_id.def_id;
734 // These don't define types.
735 hir::ItemKind::ExternCrate(_)
736 | hir::ItemKind::Use(..)
737 | hir::ItemKind::Macro(_)
738 | hir::ItemKind::Mod(_)
739 | hir::ItemKind::GlobalAsm(_) => {}
740 hir::ItemKind::ForeignMod { items, .. } => {
742 let item = tcx.hir().foreign_item(item.id);
743 tcx.ensure().generics_of(item.def_id);
744 tcx.ensure().type_of(item.def_id);
745 tcx.ensure().predicates_of(item.def_id);
747 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
748 hir::ForeignItemKind::Static(..) => {
749 let mut visitor = HirPlaceholderCollector::default();
750 visitor.visit_foreign_item(item);
751 placeholder_type_error(
765 hir::ItemKind::Enum(ref enum_definition, _) => {
766 tcx.ensure().generics_of(def_id);
767 tcx.ensure().type_of(def_id);
768 tcx.ensure().predicates_of(def_id);
769 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
771 hir::ItemKind::Impl { .. } => {
772 tcx.ensure().generics_of(def_id);
773 tcx.ensure().type_of(def_id);
774 tcx.ensure().impl_trait_ref(def_id);
775 tcx.ensure().predicates_of(def_id);
777 hir::ItemKind::Trait(..) => {
778 tcx.ensure().generics_of(def_id);
779 tcx.ensure().trait_def(def_id);
780 tcx.at(it.span).super_predicates_of(def_id);
781 tcx.ensure().predicates_of(def_id);
783 hir::ItemKind::TraitAlias(..) => {
784 tcx.ensure().generics_of(def_id);
785 tcx.at(it.span).super_predicates_of(def_id);
786 tcx.ensure().predicates_of(def_id);
788 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
789 tcx.ensure().generics_of(def_id);
790 tcx.ensure().type_of(def_id);
791 tcx.ensure().predicates_of(def_id);
793 for f in struct_def.fields() {
794 let def_id = tcx.hir().local_def_id(f.hir_id);
795 tcx.ensure().generics_of(def_id);
796 tcx.ensure().type_of(def_id);
797 tcx.ensure().predicates_of(def_id);
800 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
801 convert_variant_ctor(tcx, ctor_hir_id);
805 // Desugared from `impl Trait`, so visited by the function's return type.
806 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
807 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
811 // Don't call `type_of` on opaque types, since that depends on type
812 // checking function bodies. `check_item_type` ensures that it's called
814 hir::ItemKind::OpaqueTy(..) => {
815 tcx.ensure().generics_of(def_id);
816 tcx.ensure().predicates_of(def_id);
817 tcx.ensure().explicit_item_bounds(def_id);
819 hir::ItemKind::TyAlias(..)
820 | hir::ItemKind::Static(..)
821 | hir::ItemKind::Const(..)
822 | hir::ItemKind::Fn(..) => {
823 tcx.ensure().generics_of(def_id);
824 tcx.ensure().type_of(def_id);
825 tcx.ensure().predicates_of(def_id);
827 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
828 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
829 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
830 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
831 if let hir::TyKind::TraitObject(..) = ty.kind {
832 let mut visitor = HirPlaceholderCollector::default();
833 visitor.visit_item(it);
834 placeholder_type_error(
851 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
852 let trait_item = tcx.hir().trait_item(trait_item_id);
853 tcx.ensure().generics_of(trait_item_id.def_id);
855 match trait_item.kind {
856 hir::TraitItemKind::Fn(..) => {
857 tcx.ensure().type_of(trait_item_id.def_id);
858 tcx.ensure().fn_sig(trait_item_id.def_id);
861 hir::TraitItemKind::Const(.., Some(_)) => {
862 tcx.ensure().type_of(trait_item_id.def_id);
865 hir::TraitItemKind::Const(..) => {
866 tcx.ensure().type_of(trait_item_id.def_id);
867 // Account for `const C: _;`.
868 let mut visitor = HirPlaceholderCollector::default();
869 visitor.visit_trait_item(trait_item);
870 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
873 hir::TraitItemKind::Type(_, Some(_)) => {
874 tcx.ensure().item_bounds(trait_item_id.def_id);
875 tcx.ensure().type_of(trait_item_id.def_id);
876 // Account for `type T = _;`.
877 let mut visitor = HirPlaceholderCollector::default();
878 visitor.visit_trait_item(trait_item);
879 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
882 hir::TraitItemKind::Type(_, None) => {
883 tcx.ensure().item_bounds(trait_item_id.def_id);
884 // #74612: Visit and try to find bad placeholders
885 // even if there is no concrete type.
886 let mut visitor = HirPlaceholderCollector::default();
887 visitor.visit_trait_item(trait_item);
889 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
893 tcx.ensure().predicates_of(trait_item_id.def_id);
896 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
897 let def_id = impl_item_id.def_id;
898 tcx.ensure().generics_of(def_id);
899 tcx.ensure().type_of(def_id);
900 tcx.ensure().predicates_of(def_id);
901 let impl_item = tcx.hir().impl_item(impl_item_id);
902 match impl_item.kind {
903 hir::ImplItemKind::Fn(..) => {
904 tcx.ensure().fn_sig(def_id);
906 hir::ImplItemKind::TyAlias(_) => {
907 // Account for `type T = _;`
908 let mut visitor = HirPlaceholderCollector::default();
909 visitor.visit_impl_item(impl_item);
911 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
913 hir::ImplItemKind::Const(..) => {}
917 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
918 let def_id = tcx.hir().local_def_id(ctor_id);
919 tcx.ensure().generics_of(def_id);
920 tcx.ensure().type_of(def_id);
921 tcx.ensure().predicates_of(def_id);
924 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
925 let def = tcx.adt_def(def_id);
926 let repr_type = def.repr.discr_type();
927 let initial = repr_type.initial_discriminant(tcx);
928 let mut prev_discr = None::<Discr<'_>>;
930 // fill the discriminant values and field types
931 for variant in variants {
932 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
934 if let Some(ref e) = variant.disr_expr {
935 let expr_did = tcx.hir().local_def_id(e.hir_id);
936 def.eval_explicit_discr(tcx, expr_did.to_def_id())
937 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
940 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
943 format!("overflowed on value after {}", prev_discr.unwrap()),
946 "explicitly set `{} = {}` if that is desired outcome",
947 variant.ident, wrapped_discr
952 .unwrap_or(wrapped_discr),
955 for f in variant.data.fields() {
956 let def_id = tcx.hir().local_def_id(f.hir_id);
957 tcx.ensure().generics_of(def_id);
958 tcx.ensure().type_of(def_id);
959 tcx.ensure().predicates_of(def_id);
962 // Convert the ctor, if any. This also registers the variant as
964 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
965 convert_variant_ctor(tcx, ctor_hir_id);
972 variant_did: Option<LocalDefId>,
973 ctor_did: Option<LocalDefId>,
975 discr: ty::VariantDiscr,
976 def: &hir::VariantData<'_>,
977 adt_kind: ty::AdtKind,
978 parent_did: LocalDefId,
979 ) -> ty::VariantDef {
980 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
985 let fid = tcx.hir().local_def_id(f.hir_id);
986 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
987 if let Some(prev_span) = dup_span {
988 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
994 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
997 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
1000 let recovered = match def {
1001 hir::VariantData::Struct(_, r) => *r,
1004 ty::VariantDef::new(
1006 variant_did.map(LocalDefId::to_def_id),
1007 ctor_did.map(LocalDefId::to_def_id),
1010 CtorKind::from_hir(def),
1012 parent_did.to_def_id(),
1014 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1015 || variant_did.map_or(false, |variant_did| {
1016 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1021 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
1024 let def_id = def_id.expect_local();
1025 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1026 let item = match tcx.hir().get(hir_id) {
1027 Node::Item(item) => item,
1031 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1032 let (kind, variants) = match item.kind {
1033 ItemKind::Enum(ref def, _) => {
1034 let mut distance_from_explicit = 0;
1039 let variant_did = Some(tcx.hir().local_def_id(v.id));
1041 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1043 let discr = if let Some(ref e) = v.disr_expr {
1044 distance_from_explicit = 0;
1045 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1047 ty::VariantDiscr::Relative(distance_from_explicit)
1049 distance_from_explicit += 1;
1064 (AdtKind::Enum, variants)
1066 ItemKind::Struct(ref def, _) => {
1067 let variant_did = None::<LocalDefId>;
1068 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1070 let variants = std::iter::once(convert_variant(
1075 ty::VariantDiscr::Relative(0),
1082 (AdtKind::Struct, variants)
1084 ItemKind::Union(ref def, _) => {
1085 let variant_did = None;
1086 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1088 let variants = std::iter::once(convert_variant(
1093 ty::VariantDiscr::Relative(0),
1100 (AdtKind::Union, variants)
1104 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1107 /// Ensures that the super-predicates of the trait with a `DefId`
1108 /// of `trait_def_id` are converted and stored. This also ensures that
1109 /// the transitive super-predicates are converted.
1110 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1111 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1112 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1115 /// Ensures that the super-predicates of the trait with a `DefId`
1116 /// of `trait_def_id` are converted and stored. This also ensures that
1117 /// the transitive super-predicates are converted.
1118 fn super_predicates_that_define_assoc_type(
1120 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1121 ) -> ty::GenericPredicates<'_> {
1123 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1124 trait_def_id, assoc_name
1126 if trait_def_id.is_local() {
1127 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1128 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1130 let item = match tcx.hir().get(trait_hir_id) {
1131 Node::Item(item) => item,
1132 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
1135 let (generics, bounds) = match item.kind {
1136 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1137 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1138 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1141 let icx = ItemCtxt::new(tcx, trait_def_id);
1143 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1144 let self_param_ty = tcx.types.self_param;
1145 let superbounds1 = if let Some(assoc_name) = assoc_name {
1146 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1153 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1156 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1158 // Convert any explicit superbounds in the where-clause,
1159 // e.g., `trait Foo where Self: Bar`.
1160 // In the case of trait aliases, however, we include all bounds in the where-clause,
1161 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1162 // as one of its "superpredicates".
1163 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1164 let superbounds2 = icx.type_parameter_bounds_in_generics(
1168 OnlySelfBounds(!is_trait_alias),
1172 // Combine the two lists to form the complete set of superbounds:
1173 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1175 // Now require that immediate supertraits are converted,
1176 // which will, in turn, reach indirect supertraits.
1177 if assoc_name.is_none() {
1178 // Now require that immediate supertraits are converted,
1179 // which will, in turn, reach indirect supertraits.
1180 for &(pred, span) in superbounds {
1181 debug!("superbound: {:?}", pred);
1182 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1183 tcx.at(span).super_predicates_of(bound.def_id());
1188 ty::GenericPredicates { parent: None, predicates: superbounds }
1190 // if `assoc_name` is None, then the query should've been redirected to an
1191 // external provider
1192 assert!(assoc_name.is_some());
1193 tcx.super_predicates_of(trait_def_id)
1197 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1198 let item = tcx.hir().expect_item(def_id.expect_local());
1200 let (is_auto, unsafety, items) = match item.kind {
1201 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1202 (is_auto == hir::IsAuto::Yes, unsafety, items)
1204 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1205 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1208 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1209 if paren_sugar && !tcx.features().unboxed_closures {
1213 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1214 which traits can use parenthetical notation",
1216 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1220 let is_marker = tcx.has_attr(def_id, sym::marker);
1221 let skip_array_during_method_dispatch =
1222 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1223 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1224 ty::trait_def::TraitSpecializationKind::Marker
1225 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1226 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1228 ty::trait_def::TraitSpecializationKind::None
1230 let def_path_hash = tcx.def_path_hash(def_id);
1232 let must_implement_one_of = tcx
1235 .find(|attr| attr.has_name(sym::rustc_must_implement_one_of))
1236 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1237 // and that they are all identifiers
1238 .and_then(|attr| match attr.meta_item_list() {
1239 Some(items) if items.len() < 2 => {
1243 "the `#[rustc_must_implement_one_of]` attribute must be \
1244 used with at least 2 args",
1250 Some(items) => items
1252 .map(|item| item.ident().ok_or(item.span()))
1253 .collect::<Result<Box<[_]>, _>>()
1256 .struct_span_err(span, "must be a name of an associated function")
1260 .zip(Some(attr.span)),
1261 // Error is reported by `rustc_attr!`
1264 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1265 // functions in the trait with default implementations
1266 .and_then(|(list, attr_span)| {
1267 let errors = list.iter().filter_map(|ident| {
1268 let item = items.iter().find(|item| item.ident == *ident);
1271 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1272 if !item.defaultness.has_value() {
1276 "This function doesn't have a default implementation",
1278 .span_note(attr_span, "required by this annotation")
1288 .struct_span_err(item.span, "Not a function")
1289 .span_note(attr_span, "required by this annotation")
1291 "All `#[rustc_must_implement_one_of]` arguments \
1292 must be associated function names",
1297 .struct_span_err(ident.span, "Function not found in this trait")
1304 (errors.count() == 0).then_some(list)
1306 // Check for duplicates
1308 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1309 let mut no_dups = true;
1311 for ident in &*list {
1312 if let Some(dup) = set.insert(ident.name, ident.span) {
1314 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1316 "All `#[rustc_must_implement_one_of]` arguments \
1325 no_dups.then_some(list)
1334 skip_array_during_method_dispatch,
1337 must_implement_one_of,
1341 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1342 struct LateBoundRegionsDetector<'tcx> {
1344 outer_index: ty::DebruijnIndex,
1345 has_late_bound_regions: Option<Span>,
1348 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1349 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1350 if self.has_late_bound_regions.is_some() {
1354 hir::TyKind::BareFn(..) => {
1355 self.outer_index.shift_in(1);
1356 intravisit::walk_ty(self, ty);
1357 self.outer_index.shift_out(1);
1359 _ => intravisit::walk_ty(self, ty),
1363 fn visit_poly_trait_ref(
1365 tr: &'tcx hir::PolyTraitRef<'tcx>,
1366 m: hir::TraitBoundModifier,
1368 if self.has_late_bound_regions.is_some() {
1371 self.outer_index.shift_in(1);
1372 intravisit::walk_poly_trait_ref(self, tr, m);
1373 self.outer_index.shift_out(1);
1376 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1377 if self.has_late_bound_regions.is_some() {
1381 match self.tcx.named_region(lt.hir_id) {
1382 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1384 rl::Region::LateBound(debruijn, _, _, _)
1385 | rl::Region::LateBoundAnon(debruijn, _, _),
1386 ) if debruijn < self.outer_index => {}
1388 rl::Region::LateBound(..)
1389 | rl::Region::LateBoundAnon(..)
1390 | rl::Region::Free(..),
1393 self.has_late_bound_regions = Some(lt.span);
1399 fn has_late_bound_regions<'tcx>(
1401 generics: &'tcx hir::Generics<'tcx>,
1402 decl: &'tcx hir::FnDecl<'tcx>,
1404 let mut visitor = LateBoundRegionsDetector {
1406 outer_index: ty::INNERMOST,
1407 has_late_bound_regions: None,
1409 for param in generics.params {
1410 if let GenericParamKind::Lifetime { .. } = param.kind {
1411 if tcx.is_late_bound(param.hir_id) {
1412 return Some(param.span);
1416 visitor.visit_fn_decl(decl);
1417 visitor.has_late_bound_regions
1421 Node::TraitItem(item) => match item.kind {
1422 hir::TraitItemKind::Fn(ref sig, _) => {
1423 has_late_bound_regions(tcx, &item.generics, sig.decl)
1427 Node::ImplItem(item) => match item.kind {
1428 hir::ImplItemKind::Fn(ref sig, _) => {
1429 has_late_bound_regions(tcx, &item.generics, sig.decl)
1433 Node::ForeignItem(item) => match item.kind {
1434 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1435 has_late_bound_regions(tcx, generics, fn_decl)
1439 Node::Item(item) => match item.kind {
1440 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1441 has_late_bound_regions(tcx, generics, sig.decl)
1449 struct AnonConstInParamTyDetector {
1451 found_anon_const_in_param_ty: bool,
1455 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1456 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1457 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1458 let prev = self.in_param_ty;
1459 self.in_param_ty = true;
1461 self.in_param_ty = prev;
1465 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1466 if self.in_param_ty && self.ct == c.hir_id {
1467 self.found_anon_const_in_param_ty = true;
1469 intravisit::walk_anon_const(self, c)
1474 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1477 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1479 let node = tcx.hir().get(hir_id);
1480 let parent_def_id = match node {
1482 | Node::TraitItem(_)
1485 | Node::Field(_) => {
1486 let parent_id = tcx.hir().get_parent_item(hir_id);
1487 Some(parent_id.to_def_id())
1489 // FIXME(#43408) always enable this once `lazy_normalization` is
1490 // stable enough and does not need a feature gate anymore.
1491 Node::AnonConst(_) => {
1492 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1494 let mut in_param_ty = false;
1495 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1496 if let Some(generics) = node.generics() {
1497 let mut visitor = AnonConstInParamTyDetector {
1499 found_anon_const_in_param_ty: false,
1503 visitor.visit_generics(generics);
1504 in_param_ty = visitor.found_anon_const_in_param_ty;
1510 // We do not allow generic parameters in anon consts if we are inside
1511 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1513 } else if tcx.lazy_normalization() {
1514 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1515 // If the def_id we are calling generics_of on is an anon ct default i.e:
1517 // struct Foo<const N: usize = { .. }>;
1518 // ^^^ ^ ^^^^^^ def id of this anon const
1522 // then we only want to return generics for params to the left of `N`. If we don't do that we
1523 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1525 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1526 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1527 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1529 // We fix this by having this function return the parent's generics ourselves and truncating the
1530 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1532 // For the above code example that means we want `substs: []`
1533 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1534 // the def id of the `{ N + 1 }` anon const
1535 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1537 // This has some implications for how we get the predicates available to the anon const
1538 // see `explicit_predicates_of` for more information on this
1539 let generics = tcx.generics_of(parent_def_id.to_def_id());
1540 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1541 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1542 // In the above example this would be .params[..N#0]
1543 let params = generics.params[..param_def_idx as usize].to_owned();
1544 let param_def_id_to_index =
1545 params.iter().map(|param| (param.def_id, param.index)).collect();
1547 return ty::Generics {
1548 // we set the parent of these generics to be our parent's parent so that we
1549 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1550 // struct Foo<const N: usize, const M: usize = { ... }>;
1551 parent: generics.parent,
1552 parent_count: generics.parent_count,
1554 param_def_id_to_index,
1555 has_self: generics.has_self,
1556 has_late_bound_regions: generics.has_late_bound_regions,
1560 // HACK(eddyb) this provides the correct generics when
1561 // `feature(generic_const_expressions)` is enabled, so that const expressions
1562 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1564 // Note that we do not supply the parent generics when using
1565 // `min_const_generics`.
1566 Some(parent_def_id.to_def_id())
1568 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1570 // HACK(eddyb) this provides the correct generics for repeat
1571 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1572 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1573 // as they shouldn't be able to cause query cycle errors.
1574 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1575 if constant.hir_id() == hir_id =>
1577 Some(parent_def_id.to_def_id())
1579 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1580 if constant.hir_id == hir_id =>
1582 Some(parent_def_id.to_def_id())
1584 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1585 Some(tcx.typeck_root_def_id(def_id))
1591 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1592 Some(tcx.typeck_root_def_id(def_id))
1594 Node::Item(item) => match item.kind {
1595 ItemKind::OpaqueTy(hir::OpaqueTy {
1597 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1599 }) => Some(fn_def_id.to_def_id()),
1600 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1601 let parent_id = tcx.hir().get_parent_item(hir_id);
1602 assert_ne!(parent_id, CRATE_DEF_ID);
1603 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1604 // Opaque types are always nested within another item, and
1605 // inherit the generics of the item.
1606 Some(parent_id.to_def_id())
1613 let mut opt_self = None;
1614 let mut allow_defaults = false;
1616 let no_generics = hir::Generics::empty();
1617 let ast_generics = match node {
1618 Node::TraitItem(item) => &item.generics,
1620 Node::ImplItem(item) => &item.generics,
1622 Node::Item(item) => {
1624 ItemKind::Fn(.., ref generics, _)
1625 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1627 ItemKind::TyAlias(_, ref generics)
1628 | ItemKind::Enum(_, ref generics)
1629 | ItemKind::Struct(_, ref generics)
1630 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1631 | ItemKind::Union(_, ref generics) => {
1632 allow_defaults = true;
1636 ItemKind::Trait(_, _, ref generics, ..)
1637 | ItemKind::TraitAlias(ref generics, ..) => {
1638 // Add in the self type parameter.
1640 // Something of a hack: use the node id for the trait, also as
1641 // the node id for the Self type parameter.
1642 let param_id = item.def_id;
1644 opt_self = Some(ty::GenericParamDef {
1646 name: kw::SelfUpper,
1647 def_id: param_id.to_def_id(),
1648 pure_wrt_drop: false,
1649 kind: ty::GenericParamDefKind::Type {
1651 object_lifetime_default: rl::Set1::Empty,
1656 allow_defaults = true;
1664 Node::ForeignItem(item) => match item.kind {
1665 ForeignItemKind::Static(..) => &no_generics,
1666 ForeignItemKind::Fn(_, _, ref generics) => generics,
1667 ForeignItemKind::Type => &no_generics,
1673 let has_self = opt_self.is_some();
1674 let mut parent_has_self = false;
1675 let mut own_start = has_self as u32;
1676 let parent_count = parent_def_id.map_or(0, |def_id| {
1677 let generics = tcx.generics_of(def_id);
1679 parent_has_self = generics.has_self;
1680 own_start = generics.count() as u32;
1681 generics.parent_count + generics.params.len()
1684 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1686 if let Some(opt_self) = opt_self {
1687 params.push(opt_self);
1690 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1691 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1692 name: param.name.ident().name,
1693 index: own_start + i as u32,
1694 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1695 pure_wrt_drop: param.pure_wrt_drop,
1696 kind: ty::GenericParamDefKind::Lifetime,
1699 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1701 // Now create the real type and const parameters.
1702 let type_start = own_start - has_self as u32 + params.len() as u32;
1705 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1706 GenericParamKind::Lifetime { .. } => None,
1707 GenericParamKind::Type { ref default, synthetic, .. } => {
1708 if !allow_defaults && default.is_some() {
1709 if !tcx.features().default_type_parameter_fallback {
1710 tcx.struct_span_lint_hir(
1711 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1716 "defaults for type parameters are only allowed in \
1717 `struct`, `enum`, `type`, or `trait` definitions",
1725 let kind = ty::GenericParamDefKind::Type {
1726 has_default: default.is_some(),
1727 object_lifetime_default: object_lifetime_defaults
1729 .map_or(rl::Set1::Empty, |o| o[i]),
1733 let param_def = ty::GenericParamDef {
1734 index: type_start + i as u32,
1735 name: param.name.ident().name,
1736 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1737 pure_wrt_drop: param.pure_wrt_drop,
1743 GenericParamKind::Const { default, .. } => {
1744 if !allow_defaults && default.is_some() {
1747 "defaults for const parameters are only allowed in \
1748 `struct`, `enum`, `type`, or `trait` definitions",
1752 let param_def = ty::GenericParamDef {
1753 index: type_start + i as u32,
1754 name: param.name.ident().name,
1755 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1756 pure_wrt_drop: param.pure_wrt_drop,
1757 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1764 // provide junk type parameter defs - the only place that
1765 // cares about anything but the length is instantiation,
1766 // and we don't do that for closures.
1767 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1768 let dummy_args = if gen.is_some() {
1769 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1771 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1774 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1775 index: type_start + i as u32,
1776 name: Symbol::intern(arg),
1778 pure_wrt_drop: false,
1779 kind: ty::GenericParamDefKind::Type {
1781 object_lifetime_default: rl::Set1::Empty,
1787 // provide junk type parameter defs for const blocks.
1788 if let Node::AnonConst(_) = node {
1789 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1790 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1791 params.push(ty::GenericParamDef {
1793 name: Symbol::intern("<const_ty>"),
1795 pure_wrt_drop: false,
1796 kind: ty::GenericParamDefKind::Type {
1798 object_lifetime_default: rl::Set1::Empty,
1805 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1808 parent: parent_def_id,
1811 param_def_id_to_index,
1812 has_self: has_self || parent_has_self,
1813 has_late_bound_regions: has_late_bound_regions(tcx, node),
1817 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1818 generic_args.iter().any(|arg| match arg {
1819 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1820 hir::GenericArg::Infer(_) => true,
1825 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1826 /// use inference to provide suggestions for the appropriate type if possible.
1827 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1832 Slice(ty) => is_suggestable_infer_ty(ty),
1833 Array(ty, length) => {
1834 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1836 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1837 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1838 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1839 Path(hir::QPath::TypeRelative(ty, segment)) => {
1840 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1842 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1843 ty_opt.map_or(false, is_suggestable_infer_ty)
1844 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1850 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1851 if let hir::FnRetTy::Return(ty) = output {
1852 if is_suggestable_infer_ty(ty) {
1859 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1860 use rustc_hir::Node::*;
1863 let def_id = def_id.expect_local();
1864 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1866 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1868 match tcx.hir().get(hir_id) {
1869 TraitItem(hir::TraitItem {
1870 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1875 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1876 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1877 match get_infer_ret_ty(&sig.decl.output) {
1879 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1880 // Typeck doesn't expect erased regions to be returned from `type_of`.
1881 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match r {
1882 ty::ReErased => tcx.lifetimes.re_static,
1885 let fn_sig = ty::Binder::dummy(fn_sig);
1887 let mut visitor = HirPlaceholderCollector::default();
1888 visitor.visit_ty(ty);
1889 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1890 let ret_ty = fn_sig.skip_binder().output();
1891 if !ret_ty.references_error() {
1892 if !ret_ty.is_closure() {
1893 let ret_ty_str = match ret_ty.kind() {
1894 // Suggest a function pointer return type instead of a unique function definition
1895 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1897 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1898 _ => ret_ty.to_string(),
1900 diag.span_suggestion(
1902 "replace with the correct return type",
1904 Applicability::MaybeIncorrect,
1907 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1908 // to prevent the user from getting a papercut while trying to use the unique closure
1909 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1910 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1911 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1918 None => <dyn AstConv<'_>>::ty_of_fn(
1921 sig.header.unsafety,
1931 TraitItem(hir::TraitItem {
1932 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1936 }) => <dyn AstConv<'_>>::ty_of_fn(
1947 ForeignItem(&hir::ForeignItem {
1948 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1950 let abi = tcx.hir().get_foreign_abi(hir_id);
1951 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1954 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1955 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1957 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1958 ty::Binder::dummy(tcx.mk_fn_sig(
1962 hir::Unsafety::Normal,
1967 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1968 // Closure signatures are not like other function
1969 // signatures and cannot be accessed through `fn_sig`. For
1970 // example, a closure signature excludes the `self`
1971 // argument. In any case they are embedded within the
1972 // closure type as part of the `ClosureSubsts`.
1974 // To get the signature of a closure, you should use the
1975 // `sig` method on the `ClosureSubsts`:
1977 // substs.as_closure().sig(def_id, tcx)
1979 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1984 bug!("unexpected sort of node in fn_sig(): {:?}", x);
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>(
2047 generics: &'a hir::Generics<'a>,
2048 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2049 generics.params.iter().filter(move |param| match param.kind {
2050 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
2055 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2056 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2057 /// inferred constraints concerning which regions outlive other regions.
2058 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2059 debug!("predicates_defined_on({:?})", def_id);
2060 let mut result = tcx.explicit_predicates_of(def_id);
2061 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2062 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2063 if !inferred_outlives.is_empty() {
2065 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2066 def_id, inferred_outlives,
2068 if result.predicates.is_empty() {
2069 result.predicates = inferred_outlives;
2071 result.predicates = tcx
2073 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2077 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2081 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2082 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2083 /// `Self: Trait` predicates for traits.
2084 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2085 let mut result = tcx.predicates_defined_on(def_id);
2087 if tcx.is_trait(def_id) {
2088 // For traits, add `Self: Trait` predicate. This is
2089 // not part of the predicates that a user writes, but it
2090 // is something that one must prove in order to invoke a
2091 // method or project an associated type.
2093 // In the chalk setup, this predicate is not part of the
2094 // "predicates" for a trait item. But it is useful in
2095 // rustc because if you directly (e.g.) invoke a trait
2096 // method like `Trait::method(...)`, you must naturally
2097 // prove that the trait applies to the types that were
2098 // used, and adding the predicate into this list ensures
2099 // that this is done.
2101 // We use a DUMMY_SP here as a way to signal trait bounds that come
2102 // from the trait itself that *shouldn't* be shown as the source of
2103 // an obligation and instead be skipped. Otherwise we'd use
2104 // `tcx.def_span(def_id);`
2105 let span = rustc_span::DUMMY_SP;
2107 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2108 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2112 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2116 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2117 /// N.B., this does not include any implied/inferred constraints.
2118 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2121 debug!("explicit_predicates_of(def_id={:?})", def_id);
2123 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2124 let node = tcx.hir().get(hir_id);
2126 let mut is_trait = None;
2127 let mut is_default_impl_trait = None;
2129 let icx = ItemCtxt::new(tcx, def_id);
2131 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2133 // We use an `IndexSet` to preserves order of insertion.
2134 // Preserving the order of insertion is important here so as not to break UI tests.
2135 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2137 let ast_generics = match node {
2138 Node::TraitItem(item) => &item.generics,
2140 Node::ImplItem(item) => &item.generics,
2142 Node::Item(item) => {
2144 ItemKind::Impl(ref impl_) => {
2145 if impl_.defaultness.is_default() {
2146 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2150 ItemKind::Fn(.., ref generics, _)
2151 | ItemKind::TyAlias(_, ref generics)
2152 | ItemKind::Enum(_, ref generics)
2153 | ItemKind::Struct(_, ref generics)
2154 | ItemKind::Union(_, ref generics) => generics,
2156 ItemKind::Trait(_, _, ref generics, ..) => {
2157 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2160 ItemKind::TraitAlias(ref generics, _) => {
2161 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2164 ItemKind::OpaqueTy(OpaqueTy {
2165 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2168 // return-position impl trait
2170 // We don't inherit predicates from the parent here:
2171 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2172 // then the return type is `f::<'static, T>::{{opaque}}`.
2174 // If we inherited the predicates of `f` then we would
2175 // require that `T: 'static` to show that the return
2176 // type is well-formed.
2178 // The only way to have something with this opaque type
2179 // is from the return type of the containing function,
2180 // which will ensure that the function's predicates
2182 return ty::GenericPredicates { parent: None, predicates: &[] };
2184 ItemKind::OpaqueTy(OpaqueTy {
2186 origin: hir::OpaqueTyOrigin::TyAlias,
2189 // type-alias impl trait
2197 Node::ForeignItem(item) => match item.kind {
2198 ForeignItemKind::Static(..) => NO_GENERICS,
2199 ForeignItemKind::Fn(_, _, ref generics) => generics,
2200 ForeignItemKind::Type => NO_GENERICS,
2206 let generics = tcx.generics_of(def_id);
2207 let parent_count = generics.parent_count as u32;
2208 let has_own_self = generics.has_self && parent_count == 0;
2210 // Below we'll consider the bounds on the type parameters (including `Self`)
2211 // and the explicit where-clauses, but to get the full set of predicates
2212 // on a trait we need to add in the supertrait bounds and bounds found on
2213 // associated types.
2214 if let Some(_trait_ref) = is_trait {
2215 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2218 // In default impls, we can assume that the self type implements
2219 // the trait. So in:
2221 // default impl Foo for Bar { .. }
2223 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2224 // (see below). Recall that a default impl is not itself an impl, but rather a
2225 // set of defaults that can be incorporated into another impl.
2226 if let Some(trait_ref) = is_default_impl_trait {
2227 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2230 // Collect the region predicates that were declared inline as
2231 // well. In the case of parameters declared on a fn or method, we
2232 // have to be careful to only iterate over early-bound regions.
2233 let mut index = parent_count + has_own_self as u32;
2234 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2235 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2236 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2238 name: param.name.ident().name,
2243 GenericParamKind::Lifetime { .. } => {
2244 param.bounds.iter().for_each(|bound| match bound {
2245 hir::GenericBound::Outlives(lt) => {
2246 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2247 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2248 predicates.insert((outlives.to_predicate(tcx), lt.span));
2257 // Collect the predicates that were written inline by the user on each
2258 // type parameter (e.g., `<T: Foo>`).
2259 for param in ast_generics.params {
2261 // We already dealt with early bound lifetimes above.
2262 GenericParamKind::Lifetime { .. } => (),
2263 GenericParamKind::Type { .. } => {
2264 let name = param.name.ident().name;
2265 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2268 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2269 // Params are implicitly sized unless a `?Sized` bound is found
2270 <dyn AstConv<'_>>::add_implicitly_sized(
2274 Some((param.hir_id, ast_generics.where_clause.predicates)),
2277 predicates.extend(bounds.predicates(tcx, param_ty));
2279 GenericParamKind::Const { .. } => {
2280 // Bounds on const parameters are currently not possible.
2281 debug_assert!(param.bounds.is_empty());
2287 // Add in the bounds that appear in the where-clause.
2288 let where_clause = &ast_generics.where_clause;
2289 for predicate in where_clause.predicates {
2291 hir::WherePredicate::BoundPredicate(bound_pred) => {
2292 let ty = icx.to_ty(bound_pred.bounded_ty);
2293 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2295 // Keep the type around in a dummy predicate, in case of no bounds.
2296 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2297 // is still checked for WF.
2298 if bound_pred.bounds.is_empty() {
2299 if let ty::Param(_) = ty.kind() {
2300 // This is a `where T:`, which can be in the HIR from the
2301 // transformation that moves `?Sized` to `T`'s declaration.
2302 // We can skip the predicate because type parameters are
2303 // trivially WF, but also we *should*, to avoid exposing
2304 // users who never wrote `where Type:,` themselves, to
2305 // compiler/tooling bugs from not handling WF predicates.
2307 let span = bound_pred.bounded_ty.span;
2308 let re_root_empty = tcx.lifetimes.re_root_empty;
2309 let predicate = ty::Binder::bind_with_vars(
2310 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2316 predicates.insert((predicate.to_predicate(tcx), span));
2320 let mut bounds = Bounds::default();
2321 <dyn AstConv<'_>>::add_bounds(
2324 bound_pred.bounds.iter(),
2328 predicates.extend(bounds.predicates(tcx, ty));
2331 hir::WherePredicate::RegionPredicate(region_pred) => {
2332 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2333 predicates.extend(region_pred.bounds.iter().map(|bound| {
2334 let (r2, span) = match bound {
2335 hir::GenericBound::Outlives(lt) => {
2336 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2340 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2341 ty::OutlivesPredicate(r1, r2),
2343 .to_predicate(icx.tcx);
2349 hir::WherePredicate::EqPredicate(..) => {
2355 if tcx.features().generic_const_exprs {
2356 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2359 let mut predicates: Vec<_> = predicates.into_iter().collect();
2361 // Subtle: before we store the predicates into the tcx, we
2362 // sort them so that predicates like `T: Foo<Item=U>` come
2363 // before uses of `U`. This avoids false ambiguity errors
2364 // in trait checking. See `setup_constraining_predicates`
2366 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2367 let self_ty = tcx.type_of(def_id);
2368 let trait_ref = tcx.impl_trait_ref(def_id);
2369 cgp::setup_constraining_predicates(
2373 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2377 let result = ty::GenericPredicates {
2378 parent: generics.parent,
2379 predicates: tcx.arena.alloc_from_iter(predicates),
2381 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2385 fn const_evaluatable_predicates_of<'tcx>(
2388 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2389 struct ConstCollector<'tcx> {
2391 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2394 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2395 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2396 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2397 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2398 if let ty::ConstKind::Unevaluated(uv) = ct.val {
2399 assert_eq!(uv.promoted, None);
2400 let span = self.tcx.hir().span(c.hir_id);
2402 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2403 .to_predicate(self.tcx),
2409 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2410 // Do not look into const param defaults,
2411 // these get checked when they are actually instantiated.
2413 // We do not want the following to error:
2415 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2416 // struct Bar<const N: usize>(Foo<N, 3>);
2420 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2421 let node = tcx.hir().get(hir_id);
2423 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2424 if let hir::Node::Item(item) = node {
2425 if let hir::ItemKind::Impl(ref impl_) = item.kind {
2426 if let Some(of_trait) = &impl_.of_trait {
2427 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2428 collector.visit_trait_ref(of_trait);
2431 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2432 collector.visit_ty(impl_.self_ty);
2436 if let Some(generics) = node.generics() {
2437 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2438 collector.visit_generics(generics);
2441 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2442 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2443 collector.visit_fn_decl(fn_sig.decl);
2445 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2450 fn trait_explicit_predicates_and_bounds(
2453 ) -> ty::GenericPredicates<'_> {
2454 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2455 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2458 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2459 let def_kind = tcx.def_kind(def_id);
2460 if let DefKind::Trait = def_kind {
2461 // Remove bounds on associated types from the predicates, they will be
2462 // returned by `explicit_item_bounds`.
2463 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2464 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2466 let is_assoc_item_ty = |ty: Ty<'_>| {
2467 // For a predicate from a where clause to become a bound on an
2469 // * It must use the identity substs of the item.
2470 // * Since any generic parameters on the item are not in scope,
2471 // this means that the item is not a GAT, and its identity
2472 // substs are the same as the trait's.
2473 // * It must be an associated type for this trait (*not* a
2475 if let ty::Projection(projection) = ty.kind() {
2476 projection.substs == trait_identity_substs
2477 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2483 let predicates: Vec<_> = predicates_and_bounds
2487 .filter(|(pred, _)| match pred.kind().skip_binder() {
2488 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2489 ty::PredicateKind::Projection(proj) => {
2490 !is_assoc_item_ty(proj.projection_ty.self_ty())
2492 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2496 if predicates.len() == predicates_and_bounds.predicates.len() {
2497 predicates_and_bounds
2499 ty::GenericPredicates {
2500 parent: predicates_and_bounds.parent,
2501 predicates: tcx.arena.alloc_slice(&predicates),
2505 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2506 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2507 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2508 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2509 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2510 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2512 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2513 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2514 // ^^^ explicit_predicates_of on
2515 // parent item we dont have set as the
2516 // parent of generics returned by `generics_of`
2518 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2519 let item_def_id = tcx.hir().get_parent_item(hir_id);
2520 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2521 return tcx.explicit_predicates_of(item_def_id);
2524 gather_explicit_predicates_of(tcx, def_id)
2528 /// Converts a specific `GenericBound` from the AST into a set of
2529 /// predicates that apply to the self type. A vector is returned
2530 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2531 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2532 /// and `<T as Bar>::X == i32`).
2533 fn predicates_from_bound<'tcx>(
2534 astconv: &dyn AstConv<'tcx>,
2536 bound: &'tcx hir::GenericBound<'tcx>,
2537 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2538 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2539 let mut bounds = Bounds::default();
2540 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2541 bounds.predicates(astconv.tcx(), param_ty).collect()
2544 fn compute_sig_of_foreign_fn_decl<'tcx>(
2547 decl: &'tcx hir::FnDecl<'tcx>,
2550 ) -> ty::PolyFnSig<'tcx> {
2551 let unsafety = if abi == abi::Abi::RustIntrinsic {
2552 intrinsic_operation_unsafety(tcx.item_name(def_id))
2554 hir::Unsafety::Unsafe
2556 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2557 let fty = <dyn AstConv<'_>>::ty_of_fn(
2558 &ItemCtxt::new(tcx, def_id),
2563 &hir::Generics::empty(),
2568 // Feature gate SIMD types in FFI, since I am not sure that the
2569 // ABIs are handled at all correctly. -huonw
2570 if abi != abi::Abi::RustIntrinsic
2571 && abi != abi::Abi::PlatformIntrinsic
2572 && !tcx.features().simd_ffi
2574 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2579 .span_to_snippet(ast_ty.span)
2580 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2585 "use of SIMD type{} in FFI is highly experimental and \
2586 may result in invalid code",
2590 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2594 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2597 if let hir::FnRetTy::Return(ref ty) = decl.output {
2598 check(ty, fty.output().skip_binder())
2605 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2606 match tcx.hir().get_if_local(def_id) {
2607 Some(Node::ForeignItem(..)) => true,
2609 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2613 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2614 match tcx.hir().get_if_local(def_id) {
2616 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2617 | Node::ForeignItem(&hir::ForeignItem {
2618 kind: hir::ForeignItemKind::Static(_, mutbl),
2623 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2627 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2628 match tcx.hir().get_if_local(def_id) {
2629 Some(Node::Expr(&rustc_hir::Expr {
2630 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2632 })) => tcx.hir().body(body_id).generator_kind(),
2634 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2638 fn from_target_feature(
2641 attr: &ast::Attribute,
2642 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2643 target_features: &mut Vec<Symbol>,
2645 let list = match attr.meta_item_list() {
2649 let bad_item = |span| {
2650 let msg = "malformed `target_feature` attribute input";
2651 let code = "enable = \"..\"".to_owned();
2653 .struct_span_err(span, msg)
2654 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2657 let rust_features = tcx.features();
2659 // Only `enable = ...` is accepted in the meta-item list.
2660 if !item.has_name(sym::enable) {
2661 bad_item(item.span());
2665 // Must be of the form `enable = "..."` (a string).
2666 let value = match item.value_str() {
2667 Some(value) => value,
2669 bad_item(item.span());
2674 // We allow comma separation to enable multiple features.
2675 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2676 let feature_gate = match supported_target_features.get(feature) {
2680 format!("the feature named `{}` is not valid for this target", feature);
2681 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2684 format!("`{}` is not valid for this target", feature),
2686 if let Some(stripped) = feature.strip_prefix('+') {
2687 let valid = supported_target_features.contains_key(stripped);
2689 err.help("consider removing the leading `+` in the feature name");
2697 // Only allow features whose feature gates have been enabled.
2698 let allowed = match feature_gate.as_ref().copied() {
2699 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2700 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2701 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2702 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2703 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2704 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2705 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2706 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2707 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2708 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2709 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2710 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2711 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2712 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2713 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2714 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2715 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2716 Some(name) => bug!("unknown target feature gate {}", name),
2719 if !allowed && id.is_local() {
2721 &tcx.sess.parse_sess,
2722 feature_gate.unwrap(),
2724 &format!("the target feature `{}` is currently unstable", feature),
2728 Some(Symbol::intern(feature))
2733 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2734 use rustc_middle::mir::mono::Linkage::*;
2736 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2737 // applicable to variable declarations and may not really make sense for
2738 // Rust code in the first place but allow them anyway and trust that the
2739 // user knows what s/he's doing. Who knows, unanticipated use cases may pop
2740 // up in the future.
2742 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2743 // and don't have to be, LLVM treats them as no-ops.
2745 "appending" => Appending,
2746 "available_externally" => AvailableExternally,
2748 "extern_weak" => ExternalWeak,
2749 "external" => External,
2750 "internal" => Internal,
2751 "linkonce" => LinkOnceAny,
2752 "linkonce_odr" => LinkOnceODR,
2753 "private" => Private,
2755 "weak_odr" => WeakODR,
2757 let span = tcx.hir().span_if_local(def_id);
2758 if let Some(span) = span {
2759 tcx.sess.span_fatal(span, "invalid linkage specified")
2761 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2767 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2768 let attrs = tcx.get_attrs(id);
2770 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2771 if tcx.should_inherit_track_caller(id) {
2772 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2775 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2776 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2777 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2778 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2782 // The panic_no_unwind function called by TerminatorKind::Abort will never
2783 // unwind. If the panic handler that it invokes unwind then it will simply
2784 // call the panic handler again.
2785 if Some(id) == tcx.lang_items().panic_no_unwind() {
2786 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2789 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2791 let mut inline_span = None;
2792 let mut link_ordinal_span = None;
2793 let mut no_sanitize_span = None;
2794 for attr in attrs.iter() {
2795 if attr.has_name(sym::cold) {
2796 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2797 } else if attr.has_name(sym::rustc_allocator) {
2798 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2799 } else if attr.has_name(sym::ffi_returns_twice) {
2800 if tcx.is_foreign_item(id) {
2801 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2803 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2808 "`#[ffi_returns_twice]` may only be used on foreign functions"
2812 } else if attr.has_name(sym::ffi_pure) {
2813 if tcx.is_foreign_item(id) {
2814 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2815 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2820 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2824 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2827 // `#[ffi_pure]` is only allowed on foreign functions
2832 "`#[ffi_pure]` may only be used on foreign functions"
2836 } else if attr.has_name(sym::ffi_const) {
2837 if tcx.is_foreign_item(id) {
2838 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2840 // `#[ffi_const]` is only allowed on foreign functions
2845 "`#[ffi_const]` may only be used on foreign functions"
2849 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2850 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2851 } else if attr.has_name(sym::naked) {
2852 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2853 } else if attr.has_name(sym::no_mangle) {
2854 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2855 } else if attr.has_name(sym::no_coverage) {
2856 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2857 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2858 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2859 } else if attr.has_name(sym::used) {
2860 let inner = attr.meta_item_list();
2861 match inner.as_deref() {
2862 Some([item]) if item.has_name(sym::linker) => {
2863 if !tcx.features().used_with_arg {
2865 &tcx.sess.parse_sess,
2868 "`#[used(linker)]` is currently unstable",
2872 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
2874 Some([item]) if item.has_name(sym::compiler) => {
2875 if !tcx.features().used_with_arg {
2877 &tcx.sess.parse_sess,
2880 "`#[used(compiler)]` is currently unstable",
2884 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2890 "expected `used`, `used(compiler)` or `used(linker)`",
2894 None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
2896 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2897 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2902 "`#[cmse_nonsecure_entry]` requires C ABI"
2906 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2907 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2910 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2911 } else if attr.has_name(sym::thread_local) {
2912 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2913 } else if attr.has_name(sym::track_caller) {
2914 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2915 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2918 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2920 &tcx.sess.parse_sess,
2921 sym::closure_track_caller,
2923 "`#[track_caller]` on closures is currently unstable",
2927 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2928 } else if attr.has_name(sym::export_name) {
2929 if let Some(s) = attr.value_str() {
2930 if s.as_str().contains('\0') {
2931 // `#[export_name = ...]` will be converted to a null-terminated string,
2932 // so it may not contain any null characters.
2937 "`export_name` may not contain null characters"
2941 codegen_fn_attrs.export_name = Some(s);
2943 } else if attr.has_name(sym::target_feature) {
2944 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2945 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2946 // The `#[target_feature]` attribute is allowed on
2947 // WebAssembly targets on all functions, including safe
2948 // ones. Other targets require that `#[target_feature]` is
2949 // only applied to unsafe funtions (pending the
2950 // `target_feature_11` feature) because on most targets
2951 // execution of instructions that are not supported is
2952 // considered undefined behavior. For WebAssembly which is a
2953 // 100% safe target at execution time it's not possible to
2954 // execute undefined instructions, and even if a future
2955 // feature was added in some form for this it would be a
2956 // deterministic trap. There is no undefined behavior when
2957 // executing WebAssembly so `#[target_feature]` is allowed
2958 // on safe functions (but again, only for WebAssembly)
2960 // Note that this is also allowed if `actually_rustdoc` so
2961 // if a target is documenting some wasm-specific code then
2962 // it's not spuriously denied.
2963 } else if !tcx.features().target_feature_11 {
2964 let mut err = feature_err(
2965 &tcx.sess.parse_sess,
2966 sym::target_feature_11,
2968 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2970 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2972 } else if let Some(local_id) = id.as_local() {
2973 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2976 from_target_feature(
2980 supported_target_features,
2981 &mut codegen_fn_attrs.target_features,
2983 } else if attr.has_name(sym::linkage) {
2984 if let Some(val) = attr.value_str() {
2985 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, val.as_str()));
2987 } else if attr.has_name(sym::link_section) {
2988 if let Some(val) = attr.value_str() {
2989 if val.as_str().bytes().any(|b| b == 0) {
2991 "illegal null byte in link_section \
2995 tcx.sess.span_err(attr.span, &msg);
2997 codegen_fn_attrs.link_section = Some(val);
3000 } else if attr.has_name(sym::link_name) {
3001 codegen_fn_attrs.link_name = attr.value_str();
3002 } else if attr.has_name(sym::link_ordinal) {
3003 link_ordinal_span = Some(attr.span);
3004 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
3005 codegen_fn_attrs.link_ordinal = ordinal;
3007 } else if attr.has_name(sym::no_sanitize) {
3008 no_sanitize_span = Some(attr.span);
3009 if let Some(list) = attr.meta_item_list() {
3010 for item in list.iter() {
3011 if item.has_name(sym::address) {
3012 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
3013 } else if item.has_name(sym::cfi) {
3014 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
3015 } else if item.has_name(sym::memory) {
3016 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
3017 } else if item.has_name(sym::thread) {
3018 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
3019 } else if item.has_name(sym::hwaddress) {
3020 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
3023 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
3024 .note("expected one of: `address`, `hwaddress`, `memory` or `thread`")
3029 } else if attr.has_name(sym::instruction_set) {
3030 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
3031 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
3032 [NestedMetaItem::MetaItem(set)] => {
3034 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
3035 match segments.as_slice() {
3036 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3037 if !tcx.sess.target.has_thumb_interworking {
3039 tcx.sess.diagnostic(),
3042 "target does not support `#[instruction_set]`"
3046 } else if segments[1] == sym::a32 {
3047 Some(InstructionSetAttr::ArmA32)
3048 } else if segments[1] == sym::t32 {
3049 Some(InstructionSetAttr::ArmT32)
3056 tcx.sess.diagnostic(),
3059 "invalid instruction set specified",
3068 tcx.sess.diagnostic(),
3071 "`#[instruction_set]` requires an argument"
3078 tcx.sess.diagnostic(),
3081 "cannot specify more than one instruction set"
3089 tcx.sess.diagnostic(),
3092 "must specify an instruction set"
3098 } else if attr.has_name(sym::repr) {
3099 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3100 Some(items) => match items.as_slice() {
3101 [item] => match item.name_value_literal() {
3102 Some((sym::align, literal)) => {
3103 let alignment = rustc_attr::parse_alignment(&literal.kind);
3106 Ok(align) => Some(align),
3109 tcx.sess.diagnostic(),
3112 "invalid `repr(align)` attribute: {}",
3131 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3132 if !attr.has_name(sym::inline) {
3135 match attr.meta_kind() {
3136 Some(MetaItemKind::Word) => InlineAttr::Hint,
3137 Some(MetaItemKind::List(ref items)) => {
3138 inline_span = Some(attr.span);
3139 if items.len() != 1 {
3141 tcx.sess.diagnostic(),
3144 "expected one argument"
3148 } else if list_contains_name(&items, sym::always) {
3150 } else if list_contains_name(&items, sym::never) {
3154 tcx.sess.diagnostic(),
3164 Some(MetaItemKind::NameValue(_)) => ia,
3169 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3170 if !attr.has_name(sym::optimize) {
3173 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3174 match attr.meta_kind() {
3175 Some(MetaItemKind::Word) => {
3176 err(attr.span, "expected one argument");
3179 Some(MetaItemKind::List(ref items)) => {
3180 inline_span = Some(attr.span);
3181 if items.len() != 1 {
3182 err(attr.span, "expected one argument");
3184 } else if list_contains_name(&items, sym::size) {
3186 } else if list_contains_name(&items, sym::speed) {
3189 err(items[0].span(), "invalid argument");
3193 Some(MetaItemKind::NameValue(_)) => ia,
3198 // #73631: closures inherit `#[target_feature]` annotations
3199 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3200 let owner_id = tcx.parent(id).expect("closure should have a parent");
3203 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3206 // If a function uses #[target_feature] it can't be inlined into general
3207 // purpose functions as they wouldn't have the right target features
3208 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3210 if !codegen_fn_attrs.target_features.is_empty() {
3211 if codegen_fn_attrs.inline == InlineAttr::Always {
3212 if let Some(span) = inline_span {
3215 "cannot use `#[inline(always)]` with \
3216 `#[target_feature]`",
3222 if !codegen_fn_attrs.no_sanitize.is_empty() {
3223 if codegen_fn_attrs.inline == InlineAttr::Always {
3224 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3225 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3226 tcx.struct_span_lint_hir(
3227 lint::builtin::INLINE_NO_SANITIZE,
3231 lint.build("`no_sanitize` will have no effect after inlining")
3232 .span_note(inline_span, "inlining requested here")
3240 // Weak lang items have the same semantics as "std internal" symbols in the
3241 // sense that they're preserved through all our LTO passes and only
3242 // strippable by the linker.
3244 // Additionally weak lang items have predetermined symbol names.
3245 if tcx.is_weak_lang_item(id) {
3246 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3248 if let Some(name) = weak_lang_items::link_name(attrs) {
3249 codegen_fn_attrs.export_name = Some(name);
3250 codegen_fn_attrs.link_name = Some(name);
3252 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3254 // Internal symbols to the standard library all have no_mangle semantics in
3255 // that they have defined symbol names present in the function name. This
3256 // also applies to weak symbols where they all have known symbol names.
3257 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3258 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3261 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3262 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3263 // intrinsic functions.
3264 if let Some(name) = &codegen_fn_attrs.link_name {
3265 if name.as_str().starts_with("llvm.") {
3266 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3273 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3274 /// applied to the method prototype.
3275 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3276 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
3277 if let ty::AssocItemContainer::ImplContainer(_) = impl_item.container {
3278 if let Some(trait_item) = impl_item.trait_item_def_id {
3280 .codegen_fn_attrs(trait_item)
3282 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3290 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3291 use rustc_ast::{Lit, LitIntType, LitKind};
3292 let meta_item_list = attr.meta_item_list();
3293 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3294 let sole_meta_list = match meta_item_list {
3295 Some([item]) => item.literal(),
3298 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3299 .note("the attribute requires exactly one argument")
3305 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3306 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3307 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3308 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3309 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3311 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3312 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3313 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3314 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3315 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3316 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3317 // about LINK.EXE failing.)
3318 if *ordinal <= u16::MAX as u128 {
3319 Some(*ordinal as u16)
3321 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3323 .struct_span_err(attr.span, &msg)
3324 .note("the value may not exceed `u16::MAX`")
3330 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3331 .note("an unsuffixed integer value, e.g., `1`, is expected")
3337 fn check_link_name_xor_ordinal(
3339 codegen_fn_attrs: &CodegenFnAttrs,
3340 inline_span: Option<Span>,
3342 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3345 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3346 if let Some(span) = inline_span {
3347 tcx.sess.span_err(span, msg);
3353 /// Checks the function annotated with `#[target_feature]` is not a safe
3354 /// trait method implementation, reporting an error if it is.
3355 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3356 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3357 let node = tcx.hir().get(hir_id);
3358 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3359 let parent_id = tcx.hir().get_parent_item(hir_id);
3360 let parent_item = tcx.hir().expect_item(parent_id);
3361 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3365 "`#[target_feature(..)]` cannot be applied to safe trait method",
3367 .span_label(attr_span, "cannot be applied to safe trait method")
3368 .span_label(tcx.def_span(id), "not an `unsafe` function")