1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
17 use crate::astconv::AstConv;
18 use crate::bounds::Bounds;
19 use crate::check::intrinsic::intrinsic_operation_unsafety;
20 use crate::constrained_generic_params as cgp;
22 use crate::middle::resolve_lifetime as rl;
24 use rustc_ast::{MetaItemKind, NestedMetaItem};
25 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
26 use rustc_data_structures::captures::Captures;
27 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
28 use rustc_errors::{struct_span_err, Applicability};
30 use rustc_hir::def::{CtorKind, DefKind};
31 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
32 use rustc_hir::intravisit::{self, Visitor};
33 use rustc_hir::weak_lang_items;
34 use rustc_hir::{GenericParamKind, HirId, Node};
35 use rustc_middle::hir::nested_filter;
36 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
37 use rustc_middle::mir::mono::Linkage;
38 use rustc_middle::ty::query::Providers;
39 use rustc_middle::ty::subst::InternalSubsts;
40 use rustc_middle::ty::util::Discr;
41 use rustc_middle::ty::util::IntTypeExt;
42 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
43 use rustc_middle::ty::{ReprOptions, ToPredicate, TypeFoldable};
44 use rustc_session::lint;
45 use rustc_session::parse::feature_err;
46 use rustc_span::symbol::{kw, sym, Ident, Symbol};
47 use rustc_span::{Span, DUMMY_SP};
48 use rustc_target::spec::{abi, PanicStrategy, SanitizerSet};
49 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
55 struct OnlySelfBounds(bool);
57 ///////////////////////////////////////////////////////////////////////////
60 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
61 tcx.hir().visit_item_likes_in_module(
63 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
67 pub fn provide(providers: &mut Providers) {
68 *providers = Providers {
69 opt_const_param_of: type_of::opt_const_param_of,
70 type_of: type_of::type_of,
71 item_bounds: item_bounds::item_bounds,
72 explicit_item_bounds: item_bounds::explicit_item_bounds,
75 predicates_defined_on,
76 explicit_predicates_of,
78 super_predicates_that_define_assoc_type,
79 trait_explicit_predicates_and_bounds,
80 type_param_predicates,
90 collect_mod_item_types,
91 should_inherit_track_caller,
96 ///////////////////////////////////////////////////////////////////////////
98 /// Context specific to some particular item. This is what implements
99 /// `AstConv`. It has information about the predicates that are defined
100 /// on the trait. Unfortunately, this predicate information is
101 /// available in various different forms at various points in the
102 /// process. So we can't just store a pointer to e.g., the AST or the
103 /// parsed ty form, we have to be more flexible. To this end, the
104 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
105 /// `get_type_parameter_bounds` requests, drawing the information from
106 /// the AST (`hir::Generics`), recursively.
107 pub struct ItemCtxt<'tcx> {
112 ///////////////////////////////////////////////////////////////////////////
115 crate struct HirPlaceholderCollector(crate Vec<Span>);
117 impl<'v> Visitor<'v> for HirPlaceholderCollector {
118 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
119 if let hir::TyKind::Infer = t.kind {
122 intravisit::walk_ty(self, t)
124 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
126 hir::GenericArg::Infer(inf) => {
127 self.0.push(inf.span);
128 intravisit::walk_inf(self, inf);
130 hir::GenericArg::Type(t) => self.visit_ty(t),
134 fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
135 if let &hir::ArrayLen::Infer(_, span) = length {
138 intravisit::walk_array_len(self, length)
142 struct CollectItemTypesVisitor<'tcx> {
146 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
147 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
148 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
149 crate fn placeholder_type_error<'tcx>(
152 generics: &[hir::GenericParam<'_>],
153 placeholder_types: Vec<Span>,
155 hir_ty: Option<&hir::Ty<'_>>,
158 if placeholder_types.is_empty() {
162 let type_name = generics.next_type_param_name(None);
163 let mut sugg: Vec<_> =
164 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
166 if generics.is_empty() {
167 if let Some(span) = span {
168 sugg.push((span, format!("<{}>", type_name)));
170 } else if let Some(arg) = generics
172 .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
174 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
175 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
176 sugg.push((arg.span, (*type_name).to_string()));
178 let last = generics.iter().last().unwrap();
179 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
180 let span = last.bounds_span_for_suggestions().unwrap_or(last.span.shrink_to_hi());
181 sugg.push((span, format!(", {}", type_name)));
184 let mut err = bad_placeholder(tcx, placeholder_types, kind);
186 // Suggest, but only if it is not a function in const or static
188 let mut is_fn = false;
189 let mut is_const_or_static = false;
191 if let Some(hir_ty) = hir_ty {
192 if let hir::TyKind::BareFn(_) = hir_ty.kind {
195 // Check if parent is const or static
196 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
197 let parent_node = tcx.hir().get(parent_id);
199 is_const_or_static = matches!(
201 Node::Item(&hir::Item {
202 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
204 }) | Node::TraitItem(&hir::TraitItem {
205 kind: hir::TraitItemKind::Const(..),
207 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
212 // if function is wrapped around a const or static,
213 // then don't show the suggestion
214 if !(is_fn && is_const_or_static) {
215 err.multipart_suggestion(
216 "use type parameters instead",
218 Applicability::HasPlaceholders,
225 fn reject_placeholder_type_signatures_in_item<'tcx>(
227 item: &'tcx hir::Item<'tcx>,
229 let (generics, suggest) = match &item.kind {
230 hir::ItemKind::Union(_, generics)
231 | hir::ItemKind::Enum(_, generics)
232 | hir::ItemKind::TraitAlias(generics, _)
233 | hir::ItemKind::Trait(_, _, generics, ..)
234 | hir::ItemKind::Impl(hir::Impl { generics, .. })
235 | hir::ItemKind::Struct(_, generics) => (generics, true),
236 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
237 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
238 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
242 let mut visitor = HirPlaceholderCollector::default();
243 visitor.visit_item(item);
245 placeholder_type_error(
256 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
257 type NestedFilter = nested_filter::OnlyBodies;
259 fn nested_visit_map(&mut self) -> Self::Map {
263 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
264 convert_item(self.tcx, item.item_id());
265 reject_placeholder_type_signatures_in_item(self.tcx, item);
266 intravisit::walk_item(self, item);
269 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
270 for param in generics.params {
272 hir::GenericParamKind::Lifetime { .. } => {}
273 hir::GenericParamKind::Type { default: Some(_), .. } => {
274 let def_id = self.tcx.hir().local_def_id(param.hir_id);
275 self.tcx.ensure().type_of(def_id);
277 hir::GenericParamKind::Type { .. } => {}
278 hir::GenericParamKind::Const { default, .. } => {
279 let def_id = self.tcx.hir().local_def_id(param.hir_id);
280 self.tcx.ensure().type_of(def_id);
281 if let Some(default) = default {
282 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
283 // need to store default and type of default
284 self.tcx.ensure().type_of(default_def_id);
285 self.tcx.ensure().const_param_default(def_id);
290 intravisit::walk_generics(self, generics);
293 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
294 if let hir::ExprKind::Closure(..) = expr.kind {
295 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
296 self.tcx.ensure().generics_of(def_id);
297 // We do not call `type_of` for closures here as that
298 // depends on typecheck and would therefore hide
299 // any further errors in case one typeck fails.
301 intravisit::walk_expr(self, expr);
304 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
305 convert_trait_item(self.tcx, trait_item.trait_item_id());
306 intravisit::walk_trait_item(self, trait_item);
309 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
310 convert_impl_item(self.tcx, impl_item.impl_item_id());
311 intravisit::walk_impl_item(self, impl_item);
315 ///////////////////////////////////////////////////////////////////////////
316 // Utility types and common code for the above passes.
318 fn bad_placeholder<'tcx>(
320 mut spans: Vec<Span>,
322 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
323 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
326 let mut err = struct_span_err!(
330 "the placeholder `_` is not allowed within types on item signatures for {}",
334 err.span_label(span, "not allowed in type signatures");
339 impl<'tcx> ItemCtxt<'tcx> {
340 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
341 ItemCtxt { tcx, item_def_id }
344 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
345 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
348 pub fn hir_id(&self) -> hir::HirId {
349 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
352 pub fn node(&self) -> hir::Node<'tcx> {
353 self.tcx.hir().get(self.hir_id())
357 impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
358 fn tcx(&self) -> TyCtxt<'tcx> {
362 fn item_def_id(&self) -> Option<DefId> {
363 Some(self.item_def_id)
366 fn get_type_parameter_bounds(
371 ) -> ty::GenericPredicates<'tcx> {
372 self.tcx.at(span).type_param_predicates((
374 def_id.expect_local(),
379 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
383 fn allow_ty_infer(&self) -> bool {
387 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
388 self.tcx().ty_error_with_message(span, "bad placeholder type")
394 _: Option<&ty::GenericParamDef>,
396 ) -> &'tcx Const<'tcx> {
397 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match r {
398 ty::ReErased => self.tcx.lifetimes.re_static,
401 self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
404 fn projected_ty_from_poly_trait_ref(
408 item_segment: &hir::PathSegment<'_>,
409 poly_trait_ref: ty::PolyTraitRef<'tcx>,
411 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
412 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
420 self.tcx().mk_projection(item_def_id, item_substs)
422 // There are no late-bound regions; we can just ignore the binder.
423 let mut err = struct_span_err!(
427 "cannot use the associated type of a trait \
428 with uninferred generic parameters"
432 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
434 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
436 hir::ItemKind::Enum(_, generics)
437 | hir::ItemKind::Struct(_, generics)
438 | hir::ItemKind::Union(_, generics) => {
439 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
440 let (lt_sp, sugg) = match generics.params {
441 [] => (generics.span, format!("<{}>", lt_name)),
443 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
446 let suggestions = vec![
449 span.with_hi(item_segment.ident.span.lo()),
452 // Replace the existing lifetimes with a new named lifetime.
454 .replace_late_bound_regions(poly_trait_ref, |_| {
455 self.tcx.mk_region(ty::ReEarlyBound(
456 ty::EarlyBoundRegion {
459 name: Symbol::intern(<_name),
467 err.multipart_suggestion(
468 "use a fully qualified path with explicit lifetimes",
470 Applicability::MaybeIncorrect,
476 hir::Node::Item(hir::Item {
478 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
482 | hir::Node::ForeignItem(_)
483 | hir::Node::TraitItem(_)
484 | hir::Node::ImplItem(_) => {
485 err.span_suggestion_verbose(
486 span.with_hi(item_segment.ident.span.lo()),
487 "use a fully qualified path with inferred lifetimes",
490 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
491 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
493 Applicability::MaybeIncorrect,
499 self.tcx().ty_error()
503 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
504 // Types in item signatures are not normalized to avoid undue dependencies.
508 fn set_tainted_by_errors(&self) {
509 // There's no obvious place to track this, so just let it go.
512 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
513 // There's no place to record types from signatures?
517 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
518 fn get_new_lifetime_name<'tcx>(
520 poly_trait_ref: ty::PolyTraitRef<'tcx>,
521 generics: &hir::Generics<'tcx>,
523 let existing_lifetimes = tcx
524 .collect_referenced_late_bound_regions(&poly_trait_ref)
527 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
528 Some(name.as_str().to_string())
533 .chain(generics.params.iter().filter_map(|param| {
534 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
535 Some(param.name.ident().as_str().to_string())
540 .collect::<FxHashSet<String>>();
542 let a_to_z_repeat_n = |n| {
543 (b'a'..=b'z').map(move |c| {
544 let mut s = '\''.to_string();
545 s.extend(std::iter::repeat(char::from(c)).take(n));
550 // If all single char lifetime names are present, we wrap around and double the chars.
551 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
554 /// Returns the predicates defined on `item_def_id` of the form
555 /// `X: Foo` where `X` is the type parameter `def_id`.
556 fn type_param_predicates(
558 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
559 ) -> ty::GenericPredicates<'_> {
562 // In the AST, bounds can derive from two places. Either
563 // written inline like `<T: Foo>` or in a where-clause like
566 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
567 let param_owner = tcx.hir().ty_param_owner(param_id);
568 let generics = tcx.generics_of(param_owner);
569 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
570 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
572 // Don't look for bounds where the type parameter isn't in scope.
573 let parent = if item_def_id == param_owner.to_def_id() {
576 tcx.generics_of(item_def_id).parent
579 let mut result = parent
581 let icx = ItemCtxt::new(tcx, parent);
582 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
584 .unwrap_or_default();
585 let mut extend = None;
587 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
588 let ast_generics = match tcx.hir().get(item_hir_id) {
589 Node::TraitItem(item) => &item.generics,
591 Node::ImplItem(item) => &item.generics,
593 Node::Item(item) => {
595 ItemKind::Fn(.., ref generics, _)
596 | ItemKind::Impl(hir::Impl { ref generics, .. })
597 | ItemKind::TyAlias(_, ref generics)
598 | ItemKind::OpaqueTy(OpaqueTy {
600 origin: hir::OpaqueTyOrigin::TyAlias,
603 | ItemKind::Enum(_, ref generics)
604 | ItemKind::Struct(_, ref generics)
605 | ItemKind::Union(_, ref generics) => generics,
606 ItemKind::Trait(_, _, ref generics, ..) => {
607 // Implied `Self: Trait` and supertrait bounds.
608 if param_id == item_hir_id {
609 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
611 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
619 Node::ForeignItem(item) => match item.kind {
620 ForeignItemKind::Fn(_, _, ref generics) => generics,
627 let icx = ItemCtxt::new(tcx, item_def_id);
628 let extra_predicates = extend.into_iter().chain(
629 icx.type_parameter_bounds_in_generics(
633 OnlySelfBounds(true),
637 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
638 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
643 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
647 impl<'tcx> ItemCtxt<'tcx> {
648 /// Finds bounds from `hir::Generics`. This requires scanning through the
649 /// AST. We do this to avoid having to convert *all* the bounds, which
650 /// would create artificial cycles. Instead, we can only convert the
651 /// bounds for a type parameter `X` if `X::Foo` is used.
652 fn type_parameter_bounds_in_generics(
654 ast_generics: &'tcx hir::Generics<'tcx>,
655 param_id: hir::HirId,
657 only_self_bounds: OnlySelfBounds,
658 assoc_name: Option<Ident>,
659 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
660 let from_ty_params = ast_generics
663 .filter_map(|param| match param.kind {
664 GenericParamKind::Type { .. } | GenericParamKind::Const { .. }
665 if param.hir_id == param_id =>
671 .flat_map(|bounds| bounds.iter())
672 .filter(|b| match assoc_name {
673 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
676 .flat_map(|b| predicates_from_bound(self, ty, b, ty::List::empty()));
678 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
679 let from_where_clauses = ast_generics
683 .filter_map(|wp| match *wp {
684 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
688 let bt = if bp.is_param_bound(param_def_id) {
690 } else if !only_self_bounds.0 {
691 Some(self.to_ty(bp.bounded_ty))
695 let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id);
699 .filter(|b| match assoc_name {
700 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
703 .filter_map(move |b| bt.map(|bt| (bt, b, bvars)))
705 .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars));
707 from_ty_params.chain(from_where_clauses).collect()
710 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
711 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
714 hir::GenericBound::Trait(poly_trait_ref, _) => {
715 let trait_ref = &poly_trait_ref.trait_ref;
716 if let Some(trait_did) = trait_ref.trait_def_id() {
717 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
727 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
728 let it = tcx.hir().item(item_id);
729 debug!("convert: item {} with id {}", it.ident, it.hir_id());
730 let def_id = item_id.def_id;
733 // These don't define types.
734 hir::ItemKind::ExternCrate(_)
735 | hir::ItemKind::Use(..)
736 | hir::ItemKind::Macro(_)
737 | hir::ItemKind::Mod(_)
738 | hir::ItemKind::GlobalAsm(_) => {}
739 hir::ItemKind::ForeignMod { items, .. } => {
741 let item = tcx.hir().foreign_item(item.id);
742 tcx.ensure().generics_of(item.def_id);
743 tcx.ensure().type_of(item.def_id);
744 tcx.ensure().predicates_of(item.def_id);
746 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
747 hir::ForeignItemKind::Static(..) => {
748 let mut visitor = HirPlaceholderCollector::default();
749 visitor.visit_foreign_item(item);
750 placeholder_type_error(
764 hir::ItemKind::Enum(ref enum_definition, _) => {
765 tcx.ensure().generics_of(def_id);
766 tcx.ensure().type_of(def_id);
767 tcx.ensure().predicates_of(def_id);
768 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
770 hir::ItemKind::Impl { .. } => {
771 tcx.ensure().generics_of(def_id);
772 tcx.ensure().type_of(def_id);
773 tcx.ensure().impl_trait_ref(def_id);
774 tcx.ensure().predicates_of(def_id);
776 hir::ItemKind::Trait(..) => {
777 tcx.ensure().generics_of(def_id);
778 tcx.ensure().trait_def(def_id);
779 tcx.at(it.span).super_predicates_of(def_id);
780 tcx.ensure().predicates_of(def_id);
782 hir::ItemKind::TraitAlias(..) => {
783 tcx.ensure().generics_of(def_id);
784 tcx.at(it.span).super_predicates_of(def_id);
785 tcx.ensure().predicates_of(def_id);
787 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
788 tcx.ensure().generics_of(def_id);
789 tcx.ensure().type_of(def_id);
790 tcx.ensure().predicates_of(def_id);
792 for f in struct_def.fields() {
793 let def_id = tcx.hir().local_def_id(f.hir_id);
794 tcx.ensure().generics_of(def_id);
795 tcx.ensure().type_of(def_id);
796 tcx.ensure().predicates_of(def_id);
799 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
800 convert_variant_ctor(tcx, ctor_hir_id);
804 // Desugared from `impl Trait`, so visited by the function's return type.
805 hir::ItemKind::OpaqueTy(hir::OpaqueTy {
806 origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
810 // Don't call `type_of` on opaque types, since that depends on type
811 // checking function bodies. `check_item_type` ensures that it's called
813 hir::ItemKind::OpaqueTy(..) => {
814 tcx.ensure().generics_of(def_id);
815 tcx.ensure().predicates_of(def_id);
816 tcx.ensure().explicit_item_bounds(def_id);
818 hir::ItemKind::TyAlias(..)
819 | hir::ItemKind::Static(..)
820 | hir::ItemKind::Const(..)
821 | hir::ItemKind::Fn(..) => {
822 tcx.ensure().generics_of(def_id);
823 tcx.ensure().type_of(def_id);
824 tcx.ensure().predicates_of(def_id);
826 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
827 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
828 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
829 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
830 if let hir::TyKind::TraitObject(..) = ty.kind {
831 let mut visitor = HirPlaceholderCollector::default();
832 visitor.visit_item(it);
833 placeholder_type_error(
850 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
851 let trait_item = tcx.hir().trait_item(trait_item_id);
852 tcx.ensure().generics_of(trait_item_id.def_id);
854 match trait_item.kind {
855 hir::TraitItemKind::Fn(..) => {
856 tcx.ensure().type_of(trait_item_id.def_id);
857 tcx.ensure().fn_sig(trait_item_id.def_id);
860 hir::TraitItemKind::Const(.., Some(_)) => {
861 tcx.ensure().type_of(trait_item_id.def_id);
864 hir::TraitItemKind::Const(..) => {
865 tcx.ensure().type_of(trait_item_id.def_id);
866 // Account for `const C: _;`.
867 let mut visitor = HirPlaceholderCollector::default();
868 visitor.visit_trait_item(trait_item);
869 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
872 hir::TraitItemKind::Type(_, Some(_)) => {
873 tcx.ensure().item_bounds(trait_item_id.def_id);
874 tcx.ensure().type_of(trait_item_id.def_id);
875 // Account for `type T = _;`.
876 let mut visitor = HirPlaceholderCollector::default();
877 visitor.visit_trait_item(trait_item);
878 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
881 hir::TraitItemKind::Type(_, None) => {
882 tcx.ensure().item_bounds(trait_item_id.def_id);
883 // #74612: Visit and try to find bad placeholders
884 // even if there is no concrete type.
885 let mut visitor = HirPlaceholderCollector::default();
886 visitor.visit_trait_item(trait_item);
888 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
892 tcx.ensure().predicates_of(trait_item_id.def_id);
895 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
896 let def_id = impl_item_id.def_id;
897 tcx.ensure().generics_of(def_id);
898 tcx.ensure().type_of(def_id);
899 tcx.ensure().predicates_of(def_id);
900 let impl_item = tcx.hir().impl_item(impl_item_id);
901 match impl_item.kind {
902 hir::ImplItemKind::Fn(..) => {
903 tcx.ensure().fn_sig(def_id);
905 hir::ImplItemKind::TyAlias(_) => {
906 // Account for `type T = _;`
907 let mut visitor = HirPlaceholderCollector::default();
908 visitor.visit_impl_item(impl_item);
910 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
912 hir::ImplItemKind::Const(..) => {}
916 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
917 let def_id = tcx.hir().local_def_id(ctor_id);
918 tcx.ensure().generics_of(def_id);
919 tcx.ensure().type_of(def_id);
920 tcx.ensure().predicates_of(def_id);
923 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
924 let def = tcx.adt_def(def_id);
925 let repr_type = def.repr.discr_type();
926 let initial = repr_type.initial_discriminant(tcx);
927 let mut prev_discr = None::<Discr<'_>>;
929 // fill the discriminant values and field types
930 for variant in variants {
931 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
933 if let Some(ref e) = variant.disr_expr {
934 let expr_did = tcx.hir().local_def_id(e.hir_id);
935 def.eval_explicit_discr(tcx, expr_did.to_def_id())
936 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
939 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
942 format!("overflowed on value after {}", prev_discr.unwrap()),
945 "explicitly set `{} = {}` if that is desired outcome",
946 variant.ident, wrapped_discr
951 .unwrap_or(wrapped_discr),
954 for f in variant.data.fields() {
955 let def_id = tcx.hir().local_def_id(f.hir_id);
956 tcx.ensure().generics_of(def_id);
957 tcx.ensure().type_of(def_id);
958 tcx.ensure().predicates_of(def_id);
961 // Convert the ctor, if any. This also registers the variant as
963 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
964 convert_variant_ctor(tcx, ctor_hir_id);
971 variant_did: Option<LocalDefId>,
972 ctor_did: Option<LocalDefId>,
974 discr: ty::VariantDiscr,
975 def: &hir::VariantData<'_>,
976 adt_kind: ty::AdtKind,
977 parent_did: LocalDefId,
978 ) -> ty::VariantDef {
979 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
984 let fid = tcx.hir().local_def_id(f.hir_id);
985 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
986 if let Some(prev_span) = dup_span {
987 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
993 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
996 ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
999 let recovered = match def {
1000 hir::VariantData::Struct(_, r) => *r,
1003 ty::VariantDef::new(
1005 variant_did.map(LocalDefId::to_def_id),
1006 ctor_did.map(LocalDefId::to_def_id),
1009 CtorKind::from_hir(def),
1011 parent_did.to_def_id(),
1013 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1014 || variant_did.map_or(false, |variant_did| {
1015 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1020 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
1023 let def_id = def_id.expect_local();
1024 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1025 let item = match tcx.hir().get(hir_id) {
1026 Node::Item(item) => item,
1030 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1031 let (kind, variants) = match item.kind {
1032 ItemKind::Enum(ref def, _) => {
1033 let mut distance_from_explicit = 0;
1038 let variant_did = Some(tcx.hir().local_def_id(v.id));
1040 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1042 let discr = if let Some(ref e) = v.disr_expr {
1043 distance_from_explicit = 0;
1044 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1046 ty::VariantDiscr::Relative(distance_from_explicit)
1048 distance_from_explicit += 1;
1063 (AdtKind::Enum, variants)
1065 ItemKind::Struct(ref def, _) => {
1066 let variant_did = None::<LocalDefId>;
1067 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1069 let variants = std::iter::once(convert_variant(
1074 ty::VariantDiscr::Relative(0),
1081 (AdtKind::Struct, variants)
1083 ItemKind::Union(ref def, _) => {
1084 let variant_did = None;
1085 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1087 let variants = std::iter::once(convert_variant(
1092 ty::VariantDiscr::Relative(0),
1099 (AdtKind::Union, variants)
1103 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1106 /// Ensures that the super-predicates of the trait with a `DefId`
1107 /// of `trait_def_id` are converted and stored. This also ensures that
1108 /// the transitive super-predicates are converted.
1109 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1110 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1111 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1114 /// Ensures that the super-predicates of the trait with a `DefId`
1115 /// of `trait_def_id` are converted and stored. This also ensures that
1116 /// the transitive super-predicates are converted.
1117 fn super_predicates_that_define_assoc_type(
1119 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1120 ) -> ty::GenericPredicates<'_> {
1122 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1123 trait_def_id, assoc_name
1125 if trait_def_id.is_local() {
1126 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1127 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1129 let item = match tcx.hir().get(trait_hir_id) {
1130 Node::Item(item) => item,
1131 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
1134 let (generics, bounds) = match item.kind {
1135 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1136 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1137 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1140 let icx = ItemCtxt::new(tcx, trait_def_id);
1142 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1143 let self_param_ty = tcx.types.self_param;
1144 let superbounds1 = if let Some(assoc_name) = assoc_name {
1145 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1152 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1155 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1157 // Convert any explicit superbounds in the where-clause,
1158 // e.g., `trait Foo where Self: Bar`.
1159 // In the case of trait aliases, however, we include all bounds in the where-clause,
1160 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1161 // as one of its "superpredicates".
1162 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1163 let superbounds2 = icx.type_parameter_bounds_in_generics(
1167 OnlySelfBounds(!is_trait_alias),
1171 // Combine the two lists to form the complete set of superbounds:
1172 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1174 // Now require that immediate supertraits are converted,
1175 // which will, in turn, reach indirect supertraits.
1176 if assoc_name.is_none() {
1177 // Now require that immediate supertraits are converted,
1178 // which will, in turn, reach indirect supertraits.
1179 for &(pred, span) in superbounds {
1180 debug!("superbound: {:?}", pred);
1181 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1182 tcx.at(span).super_predicates_of(bound.def_id());
1187 ty::GenericPredicates { parent: None, predicates: superbounds }
1189 // if `assoc_name` is None, then the query should've been redirected to an
1190 // external provider
1191 assert!(assoc_name.is_some());
1192 tcx.super_predicates_of(trait_def_id)
1196 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1197 let item = tcx.hir().expect_item(def_id.expect_local());
1199 let (is_auto, unsafety, items) = match item.kind {
1200 hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
1201 (is_auto == hir::IsAuto::Yes, unsafety, items)
1203 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
1204 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1207 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1208 if paren_sugar && !tcx.features().unboxed_closures {
1212 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1213 which traits can use parenthetical notation",
1215 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1219 let is_marker = tcx.has_attr(def_id, sym::marker);
1220 let skip_array_during_method_dispatch =
1221 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1222 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1223 ty::trait_def::TraitSpecializationKind::Marker
1224 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1225 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1227 ty::trait_def::TraitSpecializationKind::None
1229 let def_path_hash = tcx.def_path_hash(def_id);
1231 let must_implement_one_of = tcx
1234 .find(|attr| attr.has_name(sym::rustc_must_implement_one_of))
1235 // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
1236 // and that they are all identifiers
1237 .and_then(|attr| match attr.meta_item_list() {
1238 Some(items) if items.len() < 2 => {
1242 "the `#[rustc_must_implement_one_of]` attribute must be \
1243 used with at least 2 args",
1249 Some(items) => items
1251 .map(|item| item.ident().ok_or(item.span()))
1252 .collect::<Result<Box<[_]>, _>>()
1255 .struct_span_err(span, "must be a name of an associated function")
1259 .zip(Some(attr.span)),
1260 // Error is reported by `rustc_attr!`
1263 // Check that all arguments of `#[rustc_must_implement_one_of]` reference
1264 // functions in the trait with default implementations
1265 .and_then(|(list, attr_span)| {
1266 let errors = list.iter().filter_map(|ident| {
1267 let item = items.iter().find(|item| item.ident == *ident);
1270 Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
1271 if !item.defaultness.has_value() {
1275 "This function doesn't have a default implementation",
1277 .span_note(attr_span, "required by this annotation")
1287 .struct_span_err(item.span, "Not a function")
1288 .span_note(attr_span, "required by this annotation")
1290 "All `#[rustc_must_implement_one_of]` arguments \
1291 must be associated function names",
1296 .struct_span_err(ident.span, "Function not found in this trait")
1303 (errors.count() == 0).then_some(list)
1305 // Check for duplicates
1307 let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
1308 let mut no_dups = true;
1310 for ident in &*list {
1311 if let Some(dup) = set.insert(ident.name, ident.span) {
1313 .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
1315 "All `#[rustc_must_implement_one_of]` arguments \
1324 no_dups.then_some(list)
1333 skip_array_during_method_dispatch,
1336 must_implement_one_of,
1340 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1341 struct LateBoundRegionsDetector<'tcx> {
1343 outer_index: ty::DebruijnIndex,
1344 has_late_bound_regions: Option<Span>,
1347 impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1348 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1349 if self.has_late_bound_regions.is_some() {
1353 hir::TyKind::BareFn(..) => {
1354 self.outer_index.shift_in(1);
1355 intravisit::walk_ty(self, ty);
1356 self.outer_index.shift_out(1);
1358 _ => intravisit::walk_ty(self, ty),
1362 fn visit_poly_trait_ref(
1364 tr: &'tcx hir::PolyTraitRef<'tcx>,
1365 m: hir::TraitBoundModifier,
1367 if self.has_late_bound_regions.is_some() {
1370 self.outer_index.shift_in(1);
1371 intravisit::walk_poly_trait_ref(self, tr, m);
1372 self.outer_index.shift_out(1);
1375 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1376 if self.has_late_bound_regions.is_some() {
1380 match self.tcx.named_region(lt.hir_id) {
1381 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1383 rl::Region::LateBound(debruijn, _, _, _)
1384 | rl::Region::LateBoundAnon(debruijn, _, _),
1385 ) if debruijn < self.outer_index => {}
1387 rl::Region::LateBound(..)
1388 | rl::Region::LateBoundAnon(..)
1389 | rl::Region::Free(..),
1392 self.has_late_bound_regions = Some(lt.span);
1398 fn has_late_bound_regions<'tcx>(
1400 generics: &'tcx hir::Generics<'tcx>,
1401 decl: &'tcx hir::FnDecl<'tcx>,
1403 let mut visitor = LateBoundRegionsDetector {
1405 outer_index: ty::INNERMOST,
1406 has_late_bound_regions: None,
1408 for param in generics.params {
1409 if let GenericParamKind::Lifetime { .. } = param.kind {
1410 if tcx.is_late_bound(param.hir_id) {
1411 return Some(param.span);
1415 visitor.visit_fn_decl(decl);
1416 visitor.has_late_bound_regions
1420 Node::TraitItem(item) => match item.kind {
1421 hir::TraitItemKind::Fn(ref sig, _) => {
1422 has_late_bound_regions(tcx, &item.generics, sig.decl)
1426 Node::ImplItem(item) => match item.kind {
1427 hir::ImplItemKind::Fn(ref sig, _) => {
1428 has_late_bound_regions(tcx, &item.generics, sig.decl)
1432 Node::ForeignItem(item) => match item.kind {
1433 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1434 has_late_bound_regions(tcx, generics, fn_decl)
1438 Node::Item(item) => match item.kind {
1439 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1440 has_late_bound_regions(tcx, generics, sig.decl)
1448 struct AnonConstInParamTyDetector {
1450 found_anon_const_in_param_ty: bool,
1454 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1455 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1456 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1457 let prev = self.in_param_ty;
1458 self.in_param_ty = true;
1460 self.in_param_ty = prev;
1464 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1465 if self.in_param_ty && self.ct == c.hir_id {
1466 self.found_anon_const_in_param_ty = true;
1468 intravisit::walk_anon_const(self, c)
1473 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1476 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1478 let node = tcx.hir().get(hir_id);
1479 let parent_def_id = match node {
1481 | Node::TraitItem(_)
1484 | Node::Field(_) => {
1485 let parent_id = tcx.hir().get_parent_item(hir_id);
1486 Some(parent_id.to_def_id())
1488 // FIXME(#43408) always enable this once `lazy_normalization` is
1489 // stable enough and does not need a feature gate anymore.
1490 Node::AnonConst(_) => {
1491 let parent_def_id = tcx.hir().get_parent_item(hir_id);
1493 let mut in_param_ty = false;
1494 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1495 if let Some(generics) = node.generics() {
1496 let mut visitor = AnonConstInParamTyDetector {
1498 found_anon_const_in_param_ty: false,
1502 visitor.visit_generics(generics);
1503 in_param_ty = visitor.found_anon_const_in_param_ty;
1509 // We do not allow generic parameters in anon consts if we are inside
1510 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1512 } else if tcx.lazy_normalization() {
1513 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1514 // If the def_id we are calling generics_of on is an anon ct default i.e:
1516 // struct Foo<const N: usize = { .. }>;
1517 // ^^^ ^ ^^^^^^ def id of this anon const
1521 // then we only want to return generics for params to the left of `N`. If we don't do that we
1522 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1524 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1525 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1526 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1528 // We fix this by having this function return the parent's generics ourselves and truncating the
1529 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1531 // For the above code example that means we want `substs: []`
1532 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1533 // the def id of the `{ N + 1 }` anon const
1534 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1536 // This has some implications for how we get the predicates available to the anon const
1537 // see `explicit_predicates_of` for more information on this
1538 let generics = tcx.generics_of(parent_def_id.to_def_id());
1539 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1540 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1541 // In the above example this would be .params[..N#0]
1542 let params = generics.params[..param_def_idx as usize].to_owned();
1543 let param_def_id_to_index =
1544 params.iter().map(|param| (param.def_id, param.index)).collect();
1546 return ty::Generics {
1547 // we set the parent of these generics to be our parent's parent so that we
1548 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1549 // struct Foo<const N: usize, const M: usize = { ... }>;
1550 parent: generics.parent,
1551 parent_count: generics.parent_count,
1553 param_def_id_to_index,
1554 has_self: generics.has_self,
1555 has_late_bound_regions: generics.has_late_bound_regions,
1559 // HACK(eddyb) this provides the correct generics when
1560 // `feature(generic_const_expressions)` is enabled, so that const expressions
1561 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1563 // Note that we do not supply the parent generics when using
1564 // `min_const_generics`.
1565 Some(parent_def_id.to_def_id())
1567 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1569 // HACK(eddyb) this provides the correct generics for repeat
1570 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1571 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1572 // as they shouldn't be able to cause query cycle errors.
1573 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1574 if constant.hir_id() == hir_id =>
1576 Some(parent_def_id.to_def_id())
1578 Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1579 if constant.hir_id == hir_id =>
1581 Some(parent_def_id.to_def_id())
1583 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1584 Some(tcx.typeck_root_def_id(def_id))
1590 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1591 Some(tcx.typeck_root_def_id(def_id))
1593 Node::Item(item) => match item.kind {
1594 ItemKind::OpaqueTy(hir::OpaqueTy {
1596 hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1598 }) => Some(fn_def_id.to_def_id()),
1599 ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
1600 let parent_id = tcx.hir().get_parent_item(hir_id);
1601 assert_ne!(parent_id, CRATE_DEF_ID);
1602 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1603 // Opaque types are always nested within another item, and
1604 // inherit the generics of the item.
1605 Some(parent_id.to_def_id())
1612 let mut opt_self = None;
1613 let mut allow_defaults = false;
1615 let no_generics = hir::Generics::empty();
1616 let ast_generics = match node {
1617 Node::TraitItem(item) => &item.generics,
1619 Node::ImplItem(item) => &item.generics,
1621 Node::Item(item) => {
1623 ItemKind::Fn(.., ref generics, _)
1624 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1626 ItemKind::TyAlias(_, ref generics)
1627 | ItemKind::Enum(_, ref generics)
1628 | ItemKind::Struct(_, ref generics)
1629 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1630 | ItemKind::Union(_, ref generics) => {
1631 allow_defaults = true;
1635 ItemKind::Trait(_, _, ref generics, ..)
1636 | ItemKind::TraitAlias(ref generics, ..) => {
1637 // Add in the self type parameter.
1639 // Something of a hack: use the node id for the trait, also as
1640 // the node id for the Self type parameter.
1641 let param_id = item.def_id;
1643 opt_self = Some(ty::GenericParamDef {
1645 name: kw::SelfUpper,
1646 def_id: param_id.to_def_id(),
1647 pure_wrt_drop: false,
1648 kind: ty::GenericParamDefKind::Type {
1650 object_lifetime_default: rl::Set1::Empty,
1655 allow_defaults = true;
1663 Node::ForeignItem(item) => match item.kind {
1664 ForeignItemKind::Static(..) => &no_generics,
1665 ForeignItemKind::Fn(_, _, ref generics) => generics,
1666 ForeignItemKind::Type => &no_generics,
1672 let has_self = opt_self.is_some();
1673 let mut parent_has_self = false;
1674 let mut own_start = has_self as u32;
1675 let parent_count = parent_def_id.map_or(0, |def_id| {
1676 let generics = tcx.generics_of(def_id);
1678 parent_has_self = generics.has_self;
1679 own_start = generics.count() as u32;
1680 generics.parent_count + generics.params.len()
1683 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1685 if let Some(opt_self) = opt_self {
1686 params.push(opt_self);
1689 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1690 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1691 name: param.name.ident().name,
1692 index: own_start + i as u32,
1693 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1694 pure_wrt_drop: param.pure_wrt_drop,
1695 kind: ty::GenericParamDefKind::Lifetime,
1698 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1700 // Now create the real type and const parameters.
1701 let type_start = own_start - has_self as u32 + params.len() as u32;
1704 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1705 GenericParamKind::Lifetime { .. } => None,
1706 GenericParamKind::Type { ref default, synthetic, .. } => {
1707 if !allow_defaults && default.is_some() {
1708 if !tcx.features().default_type_parameter_fallback {
1709 tcx.struct_span_lint_hir(
1710 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1715 "defaults for type parameters are only allowed in \
1716 `struct`, `enum`, `type`, or `trait` definitions",
1724 let kind = ty::GenericParamDefKind::Type {
1725 has_default: default.is_some(),
1726 object_lifetime_default: object_lifetime_defaults
1728 .map_or(rl::Set1::Empty, |o| o[i]),
1732 let param_def = ty::GenericParamDef {
1733 index: type_start + i as u32,
1734 name: param.name.ident().name,
1735 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1736 pure_wrt_drop: param.pure_wrt_drop,
1742 GenericParamKind::Const { default, .. } => {
1743 if !allow_defaults && default.is_some() {
1746 "defaults for const parameters are only allowed in \
1747 `struct`, `enum`, `type`, or `trait` definitions",
1751 let param_def = ty::GenericParamDef {
1752 index: type_start + i as u32,
1753 name: param.name.ident().name,
1754 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1755 pure_wrt_drop: param.pure_wrt_drop,
1756 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1763 // provide junk type parameter defs - the only place that
1764 // cares about anything but the length is instantiation,
1765 // and we don't do that for closures.
1766 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1767 let dummy_args = if gen.is_some() {
1768 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1770 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1773 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1774 index: type_start + i as u32,
1775 name: Symbol::intern(arg),
1777 pure_wrt_drop: false,
1778 kind: ty::GenericParamDefKind::Type {
1780 object_lifetime_default: rl::Set1::Empty,
1786 // provide junk type parameter defs for const blocks.
1787 if let Node::AnonConst(_) = node {
1788 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1789 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1790 params.push(ty::GenericParamDef {
1792 name: Symbol::intern("<const_ty>"),
1794 pure_wrt_drop: false,
1795 kind: ty::GenericParamDefKind::Type {
1797 object_lifetime_default: rl::Set1::Empty,
1804 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1807 parent: parent_def_id,
1810 param_def_id_to_index,
1811 has_self: has_self || parent_has_self,
1812 has_late_bound_regions: has_late_bound_regions(tcx, node),
1816 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1817 generic_args.iter().any(|arg| match arg {
1818 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1819 hir::GenericArg::Infer(_) => true,
1824 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1825 /// use inference to provide suggestions for the appropriate type if possible.
1826 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1831 Slice(ty) => is_suggestable_infer_ty(ty),
1832 Array(ty, length) => {
1833 is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
1835 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1836 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1837 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1838 Path(hir::QPath::TypeRelative(ty, segment)) => {
1839 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1841 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1842 ty_opt.map_or(false, is_suggestable_infer_ty)
1843 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1849 pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1850 if let hir::FnRetTy::Return(ty) = output {
1851 if is_suggestable_infer_ty(ty) {
1858 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1859 use rustc_hir::Node::*;
1862 let def_id = def_id.expect_local();
1863 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1865 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1867 match tcx.hir().get(hir_id) {
1868 TraitItem(hir::TraitItem {
1869 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1874 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1875 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1876 match get_infer_ret_ty(&sig.decl.output) {
1878 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1879 // Typeck doesn't expect erased regions to be returned from `type_of`.
1880 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match r {
1881 ty::ReErased => tcx.lifetimes.re_static,
1884 let fn_sig = ty::Binder::dummy(fn_sig);
1886 let mut visitor = HirPlaceholderCollector::default();
1887 visitor.visit_ty(ty);
1888 let mut diag = bad_placeholder(tcx, visitor.0, "return type");
1889 let ret_ty = fn_sig.skip_binder().output();
1890 if !ret_ty.references_error() {
1891 if !ret_ty.is_closure() {
1892 let ret_ty_str = match ret_ty.kind() {
1893 // Suggest a function pointer return type instead of a unique function definition
1894 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1896 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1897 _ => ret_ty.to_string(),
1899 diag.span_suggestion(
1901 "replace with the correct return type",
1903 Applicability::MaybeIncorrect,
1906 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1907 // to prevent the user from getting a papercut while trying to use the unique closure
1908 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1909 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1910 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1917 None => <dyn AstConv<'_>>::ty_of_fn(
1920 sig.header.unsafety,
1930 TraitItem(hir::TraitItem {
1931 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1935 }) => <dyn AstConv<'_>>::ty_of_fn(
1946 ForeignItem(&hir::ForeignItem {
1947 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1949 let abi = tcx.hir().get_foreign_abi(hir_id);
1950 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1953 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1954 let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
1956 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1957 ty::Binder::dummy(tcx.mk_fn_sig(
1961 hir::Unsafety::Normal,
1966 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1967 // Closure signatures are not like other function
1968 // signatures and cannot be accessed through `fn_sig`. For
1969 // example, a closure signature excludes the `self`
1970 // argument. In any case they are embedded within the
1971 // closure type as part of the `ClosureSubsts`.
1973 // To get the signature of a closure, you should use the
1974 // `sig` method on the `ClosureSubsts`:
1976 // substs.as_closure().sig(def_id, tcx)
1978 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1983 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1988 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1989 let icx = ItemCtxt::new(tcx, def_id);
1990 match tcx.hir().expect_item(def_id.expect_local()).kind {
1991 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1992 let selfty = tcx.type_of(def_id);
1993 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1999 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
2000 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
2001 let item = tcx.hir().expect_item(def_id.expect_local());
2003 hir::ItemKind::Impl(hir::Impl {
2004 polarity: hir::ImplPolarity::Negative(span),
2008 if is_rustc_reservation {
2009 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
2010 tcx.sess.span_err(span, "reservation impls can't be negative");
2012 ty::ImplPolarity::Negative
2014 hir::ItemKind::Impl(hir::Impl {
2015 polarity: hir::ImplPolarity::Positive,
2019 if is_rustc_reservation {
2020 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2022 ty::ImplPolarity::Positive
2024 hir::ItemKind::Impl(hir::Impl {
2025 polarity: hir::ImplPolarity::Positive,
2029 if is_rustc_reservation {
2030 ty::ImplPolarity::Reservation
2032 ty::ImplPolarity::Positive
2035 item => bug!("impl_polarity: {:?} not an impl", item),
2039 /// Returns the early-bound lifetimes declared in this generics
2040 /// listing. For anything other than fns/methods, this is just all
2041 /// the lifetimes that are declared. For fns or methods, we have to
2042 /// screen out those that do not appear in any where-clauses etc using
2043 /// `resolve_lifetime::early_bound_lifetimes`.
2044 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2046 generics: &'a hir::Generics<'a>,
2047 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2048 generics.params.iter().filter(move |param| match param.kind {
2049 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
2054 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2055 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2056 /// inferred constraints concerning which regions outlive other regions.
2057 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2058 debug!("predicates_defined_on({:?})", def_id);
2059 let mut result = tcx.explicit_predicates_of(def_id);
2060 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2061 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2062 if !inferred_outlives.is_empty() {
2064 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2065 def_id, inferred_outlives,
2067 if result.predicates.is_empty() {
2068 result.predicates = inferred_outlives;
2070 result.predicates = tcx
2072 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2076 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2080 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2081 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2082 /// `Self: Trait` predicates for traits.
2083 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2084 let mut result = tcx.predicates_defined_on(def_id);
2086 if tcx.is_trait(def_id) {
2087 // For traits, add `Self: Trait` predicate. This is
2088 // not part of the predicates that a user writes, but it
2089 // is something that one must prove in order to invoke a
2090 // method or project an associated type.
2092 // In the chalk setup, this predicate is not part of the
2093 // "predicates" for a trait item. But it is useful in
2094 // rustc because if you directly (e.g.) invoke a trait
2095 // method like `Trait::method(...)`, you must naturally
2096 // prove that the trait applies to the types that were
2097 // used, and adding the predicate into this list ensures
2098 // that this is done.
2100 // We use a DUMMY_SP here as a way to signal trait bounds that come
2101 // from the trait itself that *shouldn't* be shown as the source of
2102 // an obligation and instead be skipped. Otherwise we'd use
2103 // `tcx.def_span(def_id);`
2104 let span = rustc_span::DUMMY_SP;
2106 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2107 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2111 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2115 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2116 /// N.B., this does not include any implied/inferred constraints.
2117 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2120 debug!("explicit_predicates_of(def_id={:?})", def_id);
2122 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2123 let node = tcx.hir().get(hir_id);
2125 let mut is_trait = None;
2126 let mut is_default_impl_trait = None;
2128 let icx = ItemCtxt::new(tcx, def_id);
2130 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2132 // We use an `IndexSet` to preserves order of insertion.
2133 // Preserving the order of insertion is important here so as not to break UI tests.
2134 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2136 let ast_generics = match node {
2137 Node::TraitItem(item) => &item.generics,
2139 Node::ImplItem(item) => &item.generics,
2141 Node::Item(item) => {
2143 ItemKind::Impl(ref impl_) => {
2144 if impl_.defaultness.is_default() {
2145 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2149 ItemKind::Fn(.., ref generics, _)
2150 | ItemKind::TyAlias(_, ref generics)
2151 | ItemKind::Enum(_, ref generics)
2152 | ItemKind::Struct(_, ref generics)
2153 | ItemKind::Union(_, ref generics) => generics,
2155 ItemKind::Trait(_, _, ref generics, ..) => {
2156 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2159 ItemKind::TraitAlias(ref generics, _) => {
2160 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2163 ItemKind::OpaqueTy(OpaqueTy {
2164 origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
2167 // return-position impl trait
2169 // We don't inherit predicates from the parent here:
2170 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2171 // then the return type is `f::<'static, T>::{{opaque}}`.
2173 // If we inherited the predicates of `f` then we would
2174 // require that `T: 'static` to show that the return
2175 // type is well-formed.
2177 // The only way to have something with this opaque type
2178 // is from the return type of the containing function,
2179 // which will ensure that the function's predicates
2181 return ty::GenericPredicates { parent: None, predicates: &[] };
2183 ItemKind::OpaqueTy(OpaqueTy {
2185 origin: hir::OpaqueTyOrigin::TyAlias,
2188 // type-alias impl trait
2196 Node::ForeignItem(item) => match item.kind {
2197 ForeignItemKind::Static(..) => NO_GENERICS,
2198 ForeignItemKind::Fn(_, _, ref generics) => generics,
2199 ForeignItemKind::Type => NO_GENERICS,
2205 let generics = tcx.generics_of(def_id);
2206 let parent_count = generics.parent_count as u32;
2207 let has_own_self = generics.has_self && parent_count == 0;
2209 // Below we'll consider the bounds on the type parameters (including `Self`)
2210 // and the explicit where-clauses, but to get the full set of predicates
2211 // on a trait we need to add in the supertrait bounds and bounds found on
2212 // associated types.
2213 if let Some(_trait_ref) = is_trait {
2214 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2217 // In default impls, we can assume that the self type implements
2218 // the trait. So in:
2220 // default impl Foo for Bar { .. }
2222 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2223 // (see below). Recall that a default impl is not itself an impl, but rather a
2224 // set of defaults that can be incorporated into another impl.
2225 if let Some(trait_ref) = is_default_impl_trait {
2226 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2229 // Collect the region predicates that were declared inline as
2230 // well. In the case of parameters declared on a fn or method, we
2231 // have to be careful to only iterate over early-bound regions.
2232 let mut index = parent_count + has_own_self as u32;
2233 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2234 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2235 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2237 name: param.name.ident().name,
2242 GenericParamKind::Lifetime { .. } => {
2243 param.bounds.iter().for_each(|bound| match bound {
2244 hir::GenericBound::Outlives(lt) => {
2245 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2246 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2247 predicates.insert((outlives.to_predicate(tcx), lt.span));
2256 // Collect the predicates that were written inline by the user on each
2257 // type parameter (e.g., `<T: Foo>`).
2258 for param in ast_generics.params {
2260 // We already dealt with early bound lifetimes above.
2261 GenericParamKind::Lifetime { .. } => (),
2262 GenericParamKind::Type { .. } => {
2263 let name = param.name.ident().name;
2264 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2267 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2268 // Params are implicitly sized unless a `?Sized` bound is found
2269 <dyn AstConv<'_>>::add_implicitly_sized(
2273 Some((param.hir_id, ast_generics.where_clause.predicates)),
2276 predicates.extend(bounds.predicates(tcx, param_ty));
2278 GenericParamKind::Const { .. } => {
2279 // Bounds on const parameters are currently not possible.
2280 debug_assert!(param.bounds.is_empty());
2286 // Add in the bounds that appear in the where-clause.
2287 let where_clause = &ast_generics.where_clause;
2288 for predicate in where_clause.predicates {
2290 hir::WherePredicate::BoundPredicate(bound_pred) => {
2291 let ty = icx.to_ty(bound_pred.bounded_ty);
2292 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2294 // Keep the type around in a dummy predicate, in case of no bounds.
2295 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2296 // is still checked for WF.
2297 if bound_pred.bounds.is_empty() {
2298 if let ty::Param(_) = ty.kind() {
2299 // This is a `where T:`, which can be in the HIR from the
2300 // transformation that moves `?Sized` to `T`'s declaration.
2301 // We can skip the predicate because type parameters are
2302 // trivially WF, but also we *should*, to avoid exposing
2303 // users who never wrote `where Type:,` themselves, to
2304 // compiler/tooling bugs from not handling WF predicates.
2306 let span = bound_pred.bounded_ty.span;
2307 let re_root_empty = tcx.lifetimes.re_root_empty;
2308 let predicate = ty::Binder::bind_with_vars(
2309 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2315 predicates.insert((predicate.to_predicate(tcx), span));
2319 let mut bounds = Bounds::default();
2320 <dyn AstConv<'_>>::add_bounds(
2323 bound_pred.bounds.iter(),
2327 predicates.extend(bounds.predicates(tcx, ty));
2330 hir::WherePredicate::RegionPredicate(region_pred) => {
2331 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2332 predicates.extend(region_pred.bounds.iter().map(|bound| {
2333 let (r2, span) = match bound {
2334 hir::GenericBound::Outlives(lt) => {
2335 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2339 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2340 ty::OutlivesPredicate(r1, r2),
2342 .to_predicate(icx.tcx);
2348 hir::WherePredicate::EqPredicate(..) => {
2354 if tcx.features().generic_const_exprs {
2355 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2358 let mut predicates: Vec<_> = predicates.into_iter().collect();
2360 // Subtle: before we store the predicates into the tcx, we
2361 // sort them so that predicates like `T: Foo<Item=U>` come
2362 // before uses of `U`. This avoids false ambiguity errors
2363 // in trait checking. See `setup_constraining_predicates`
2365 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2366 let self_ty = tcx.type_of(def_id);
2367 let trait_ref = tcx.impl_trait_ref(def_id);
2368 cgp::setup_constraining_predicates(
2372 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2376 let result = ty::GenericPredicates {
2377 parent: generics.parent,
2378 predicates: tcx.arena.alloc_from_iter(predicates),
2380 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2384 fn const_evaluatable_predicates_of<'tcx>(
2387 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2388 struct ConstCollector<'tcx> {
2390 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2393 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2394 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2395 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2396 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2397 if let ty::ConstKind::Unevaluated(uv) = ct.val {
2398 assert_eq!(uv.promoted, None);
2399 let span = self.tcx.hir().span(c.hir_id);
2401 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2402 .to_predicate(self.tcx),
2408 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2409 // Do not look into const param defaults,
2410 // these get checked when they are actually instantiated.
2412 // We do not want the following to error:
2414 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2415 // struct Bar<const N: usize>(Foo<N, 3>);
2419 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2420 let node = tcx.hir().get(hir_id);
2422 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2423 if let hir::Node::Item(item) = node {
2424 if let hir::ItemKind::Impl(ref impl_) = item.kind {
2425 if let Some(of_trait) = &impl_.of_trait {
2426 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2427 collector.visit_trait_ref(of_trait);
2430 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2431 collector.visit_ty(impl_.self_ty);
2435 if let Some(generics) = node.generics() {
2436 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2437 collector.visit_generics(generics);
2440 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2441 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2442 collector.visit_fn_decl(fn_sig.decl);
2444 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2449 fn trait_explicit_predicates_and_bounds(
2452 ) -> ty::GenericPredicates<'_> {
2453 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2454 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2457 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2458 let def_kind = tcx.def_kind(def_id);
2459 if let DefKind::Trait = def_kind {
2460 // Remove bounds on associated types from the predicates, they will be
2461 // returned by `explicit_item_bounds`.
2462 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2463 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2465 let is_assoc_item_ty = |ty: Ty<'_>| {
2466 // For a predicate from a where clause to become a bound on an
2468 // * It must use the identity substs of the item.
2469 // * Since any generic parameters on the item are not in scope,
2470 // this means that the item is not a GAT, and its identity
2471 // substs are the same as the trait's.
2472 // * It must be an associated type for this trait (*not* a
2474 if let ty::Projection(projection) = ty.kind() {
2475 projection.substs == trait_identity_substs
2476 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2482 let predicates: Vec<_> = predicates_and_bounds
2486 .filter(|(pred, _)| match pred.kind().skip_binder() {
2487 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2488 ty::PredicateKind::Projection(proj) => {
2489 !is_assoc_item_ty(proj.projection_ty.self_ty())
2491 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2495 if predicates.len() == predicates_and_bounds.predicates.len() {
2496 predicates_and_bounds
2498 ty::GenericPredicates {
2499 parent: predicates_and_bounds.parent,
2500 predicates: tcx.arena.alloc_slice(&predicates),
2504 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2505 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2506 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2507 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2508 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2509 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2511 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2512 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2513 // ^^^ explicit_predicates_of on
2514 // parent item we dont have set as the
2515 // parent of generics returned by `generics_of`
2517 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2518 let item_def_id = tcx.hir().get_parent_item(hir_id);
2519 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2520 return tcx.explicit_predicates_of(item_def_id);
2523 gather_explicit_predicates_of(tcx, def_id)
2527 /// Converts a specific `GenericBound` from the AST into a set of
2528 /// predicates that apply to the self type. A vector is returned
2529 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2530 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2531 /// and `<T as Bar>::X == i32`).
2532 fn predicates_from_bound<'tcx>(
2533 astconv: &dyn AstConv<'tcx>,
2535 bound: &'tcx hir::GenericBound<'tcx>,
2536 bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
2537 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2538 let mut bounds = Bounds::default();
2539 astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
2540 bounds.predicates(astconv.tcx(), param_ty).collect()
2543 fn compute_sig_of_foreign_fn_decl<'tcx>(
2546 decl: &'tcx hir::FnDecl<'tcx>,
2549 ) -> ty::PolyFnSig<'tcx> {
2550 let unsafety = if abi == abi::Abi::RustIntrinsic {
2551 intrinsic_operation_unsafety(tcx.item_name(def_id))
2553 hir::Unsafety::Unsafe
2555 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2556 let fty = <dyn AstConv<'_>>::ty_of_fn(
2557 &ItemCtxt::new(tcx, def_id),
2562 &hir::Generics::empty(),
2567 // Feature gate SIMD types in FFI, since I am not sure that the
2568 // ABIs are handled at all correctly. -huonw
2569 if abi != abi::Abi::RustIntrinsic
2570 && abi != abi::Abi::PlatformIntrinsic
2571 && !tcx.features().simd_ffi
2573 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2578 .span_to_snippet(ast_ty.span)
2579 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2584 "use of SIMD type{} in FFI is highly experimental and \
2585 may result in invalid code",
2589 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2593 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2596 if let hir::FnRetTy::Return(ref ty) = decl.output {
2597 check(ty, fty.output().skip_binder())
2604 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2605 match tcx.hir().get_if_local(def_id) {
2606 Some(Node::ForeignItem(..)) => true,
2608 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2612 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2613 match tcx.hir().get_if_local(def_id) {
2615 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2616 | Node::ForeignItem(&hir::ForeignItem {
2617 kind: hir::ForeignItemKind::Static(_, mutbl),
2622 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2626 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2627 match tcx.hir().get_if_local(def_id) {
2628 Some(Node::Expr(&rustc_hir::Expr {
2629 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2631 })) => tcx.hir().body(body_id).generator_kind(),
2633 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2637 fn from_target_feature(
2640 attr: &ast::Attribute,
2641 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2642 target_features: &mut Vec<Symbol>,
2644 let list = match attr.meta_item_list() {
2648 let bad_item = |span| {
2649 let msg = "malformed `target_feature` attribute input";
2650 let code = "enable = \"..\"".to_owned();
2652 .struct_span_err(span, msg)
2653 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2656 let rust_features = tcx.features();
2658 // Only `enable = ...` is accepted in the meta-item list.
2659 if !item.has_name(sym::enable) {
2660 bad_item(item.span());
2664 // Must be of the form `enable = "..."` (a string).
2665 let value = match item.value_str() {
2666 Some(value) => value,
2668 bad_item(item.span());
2673 // We allow comma separation to enable multiple features.
2674 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2675 let feature_gate = match supported_target_features.get(feature) {
2679 format!("the feature named `{}` is not valid for this target", feature);
2680 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2683 format!("`{}` is not valid for this target", feature),
2685 if let Some(stripped) = feature.strip_prefix('+') {
2686 let valid = supported_target_features.contains_key(stripped);
2688 err.help("consider removing the leading `+` in the feature name");
2696 // Only allow features whose feature gates have been enabled.
2697 let allowed = match feature_gate.as_ref().copied() {
2698 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2699 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2700 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2701 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2702 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2703 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2704 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2705 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2706 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2707 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2708 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2709 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2710 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2711 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2712 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2713 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2714 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2715 Some(name) => bug!("unknown target feature gate {}", name),
2718 if !allowed && id.is_local() {
2720 &tcx.sess.parse_sess,
2721 feature_gate.unwrap(),
2723 &format!("the target feature `{}` is currently unstable", feature),
2727 Some(Symbol::intern(feature))
2732 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2733 use rustc_middle::mir::mono::Linkage::*;
2735 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2736 // applicable to variable declarations and may not really make sense for
2737 // Rust code in the first place but allow them anyway and trust that the
2738 // user knows what s/he's doing. Who knows, unanticipated use cases may pop
2739 // up in the future.
2741 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2742 // and don't have to be, LLVM treats them as no-ops.
2744 "appending" => Appending,
2745 "available_externally" => AvailableExternally,
2747 "extern_weak" => ExternalWeak,
2748 "external" => External,
2749 "internal" => Internal,
2750 "linkonce" => LinkOnceAny,
2751 "linkonce_odr" => LinkOnceODR,
2752 "private" => Private,
2754 "weak_odr" => WeakODR,
2756 let span = tcx.hir().span_if_local(def_id);
2757 if let Some(span) = span {
2758 tcx.sess.span_fatal(span, "invalid linkage specified")
2760 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2766 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2767 let attrs = tcx.get_attrs(id);
2769 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2770 if tcx.should_inherit_track_caller(id) {
2771 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2774 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2775 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2776 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2777 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2781 // The panic_no_unwind function called by TerminatorKind::Abort will never
2782 // unwind. If the panic handler that it invokes unwind then it will simply
2783 // call the panic handler again.
2784 if Some(id) == tcx.lang_items().panic_no_unwind() {
2785 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2788 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2790 let mut inline_span = None;
2791 let mut link_ordinal_span = None;
2792 let mut no_sanitize_span = None;
2793 for attr in attrs.iter() {
2794 if attr.has_name(sym::cold) {
2795 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2796 } else if attr.has_name(sym::rustc_allocator) {
2797 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2798 } else if attr.has_name(sym::ffi_returns_twice) {
2799 if tcx.is_foreign_item(id) {
2800 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2802 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2807 "`#[ffi_returns_twice]` may only be used on foreign functions"
2811 } else if attr.has_name(sym::ffi_pure) {
2812 if tcx.is_foreign_item(id) {
2813 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2814 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2819 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2823 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2826 // `#[ffi_pure]` is only allowed on foreign functions
2831 "`#[ffi_pure]` may only be used on foreign functions"
2835 } else if attr.has_name(sym::ffi_const) {
2836 if tcx.is_foreign_item(id) {
2837 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2839 // `#[ffi_const]` is only allowed on foreign functions
2844 "`#[ffi_const]` may only be used on foreign functions"
2848 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2849 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2850 } else if attr.has_name(sym::naked) {
2851 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2852 } else if attr.has_name(sym::no_mangle) {
2853 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2854 } else if attr.has_name(sym::no_coverage) {
2855 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2856 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2857 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2858 } else if attr.has_name(sym::used) {
2859 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2860 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2861 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2866 "`#[cmse_nonsecure_entry]` requires C ABI"
2870 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2871 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2874 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2875 } else if attr.has_name(sym::thread_local) {
2876 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2877 } else if attr.has_name(sym::track_caller) {
2878 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2879 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2882 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2884 &tcx.sess.parse_sess,
2885 sym::closure_track_caller,
2887 "`#[track_caller]` on closures is currently unstable",
2891 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2892 } else if attr.has_name(sym::export_name) {
2893 if let Some(s) = attr.value_str() {
2894 if s.as_str().contains('\0') {
2895 // `#[export_name = ...]` will be converted to a null-terminated string,
2896 // so it may not contain any null characters.
2901 "`export_name` may not contain null characters"
2905 codegen_fn_attrs.export_name = Some(s);
2907 } else if attr.has_name(sym::target_feature) {
2908 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2909 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2910 // The `#[target_feature]` attribute is allowed on
2911 // WebAssembly targets on all functions, including safe
2912 // ones. Other targets require that `#[target_feature]` is
2913 // only applied to unsafe funtions (pending the
2914 // `target_feature_11` feature) because on most targets
2915 // execution of instructions that are not supported is
2916 // considered undefined behavior. For WebAssembly which is a
2917 // 100% safe target at execution time it's not possible to
2918 // execute undefined instructions, and even if a future
2919 // feature was added in some form for this it would be a
2920 // deterministic trap. There is no undefined behavior when
2921 // executing WebAssembly so `#[target_feature]` is allowed
2922 // on safe functions (but again, only for WebAssembly)
2924 // Note that this is also allowed if `actually_rustdoc` so
2925 // if a target is documenting some wasm-specific code then
2926 // it's not spuriously denied.
2927 } else if !tcx.features().target_feature_11 {
2928 let mut err = feature_err(
2929 &tcx.sess.parse_sess,
2930 sym::target_feature_11,
2932 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2934 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2936 } else if let Some(local_id) = id.as_local() {
2937 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2940 from_target_feature(
2944 supported_target_features,
2945 &mut codegen_fn_attrs.target_features,
2947 } else if attr.has_name(sym::linkage) {
2948 if let Some(val) = attr.value_str() {
2949 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, val.as_str()));
2951 } else if attr.has_name(sym::link_section) {
2952 if let Some(val) = attr.value_str() {
2953 if val.as_str().bytes().any(|b| b == 0) {
2955 "illegal null byte in link_section \
2959 tcx.sess.span_err(attr.span, &msg);
2961 codegen_fn_attrs.link_section = Some(val);
2964 } else if attr.has_name(sym::link_name) {
2965 codegen_fn_attrs.link_name = attr.value_str();
2966 } else if attr.has_name(sym::link_ordinal) {
2967 link_ordinal_span = Some(attr.span);
2968 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2969 codegen_fn_attrs.link_ordinal = ordinal;
2971 } else if attr.has_name(sym::no_sanitize) {
2972 no_sanitize_span = Some(attr.span);
2973 if let Some(list) = attr.meta_item_list() {
2974 for item in list.iter() {
2975 if item.has_name(sym::address) {
2976 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2977 } else if item.has_name(sym::cfi) {
2978 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2979 } else if item.has_name(sym::memory) {
2980 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2981 } else if item.has_name(sym::thread) {
2982 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2983 } else if item.has_name(sym::hwaddress) {
2984 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2987 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2988 .note("expected one of: `address`, `hwaddress`, `memory` or `thread`")
2993 } else if attr.has_name(sym::instruction_set) {
2994 codegen_fn_attrs.instruction_set = match attr.meta_kind() {
2995 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
2996 [NestedMetaItem::MetaItem(set)] => {
2998 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
2999 match segments.as_slice() {
3000 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
3001 if !tcx.sess.target.has_thumb_interworking {
3003 tcx.sess.diagnostic(),
3006 "target does not support `#[instruction_set]`"
3010 } else if segments[1] == sym::a32 {
3011 Some(InstructionSetAttr::ArmA32)
3012 } else if segments[1] == sym::t32 {
3013 Some(InstructionSetAttr::ArmT32)
3020 tcx.sess.diagnostic(),
3023 "invalid instruction set specified",
3032 tcx.sess.diagnostic(),
3035 "`#[instruction_set]` requires an argument"
3042 tcx.sess.diagnostic(),
3045 "cannot specify more than one instruction set"
3053 tcx.sess.diagnostic(),
3056 "must specify an instruction set"
3062 } else if attr.has_name(sym::repr) {
3063 codegen_fn_attrs.alignment = match attr.meta_item_list() {
3064 Some(items) => match items.as_slice() {
3065 [item] => match item.name_value_literal() {
3066 Some((sym::align, literal)) => {
3067 let alignment = rustc_attr::parse_alignment(&literal.kind);
3070 Ok(align) => Some(align),
3073 tcx.sess.diagnostic(),
3076 "invalid `repr(align)` attribute: {}",
3095 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
3096 if !attr.has_name(sym::inline) {
3099 match attr.meta_kind() {
3100 Some(MetaItemKind::Word) => InlineAttr::Hint,
3101 Some(MetaItemKind::List(ref items)) => {
3102 inline_span = Some(attr.span);
3103 if items.len() != 1 {
3105 tcx.sess.diagnostic(),
3108 "expected one argument"
3112 } else if list_contains_name(&items, sym::always) {
3114 } else if list_contains_name(&items, sym::never) {
3118 tcx.sess.diagnostic(),
3128 Some(MetaItemKind::NameValue(_)) => ia,
3133 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3134 if !attr.has_name(sym::optimize) {
3137 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3138 match attr.meta_kind() {
3139 Some(MetaItemKind::Word) => {
3140 err(attr.span, "expected one argument");
3143 Some(MetaItemKind::List(ref items)) => {
3144 inline_span = Some(attr.span);
3145 if items.len() != 1 {
3146 err(attr.span, "expected one argument");
3148 } else if list_contains_name(&items, sym::size) {
3150 } else if list_contains_name(&items, sym::speed) {
3153 err(items[0].span(), "invalid argument");
3157 Some(MetaItemKind::NameValue(_)) => ia,
3162 // #73631: closures inherit `#[target_feature]` annotations
3163 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3164 let owner_id = tcx.parent(id).expect("closure should have a parent");
3167 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3170 // If a function uses #[target_feature] it can't be inlined into general
3171 // purpose functions as they wouldn't have the right target features
3172 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3174 if !codegen_fn_attrs.target_features.is_empty() {
3175 if codegen_fn_attrs.inline == InlineAttr::Always {
3176 if let Some(span) = inline_span {
3179 "cannot use `#[inline(always)]` with \
3180 `#[target_feature]`",
3186 if !codegen_fn_attrs.no_sanitize.is_empty() {
3187 if codegen_fn_attrs.inline == InlineAttr::Always {
3188 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3189 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3190 tcx.struct_span_lint_hir(
3191 lint::builtin::INLINE_NO_SANITIZE,
3195 lint.build("`no_sanitize` will have no effect after inlining")
3196 .span_note(inline_span, "inlining requested here")
3204 // Weak lang items have the same semantics as "std internal" symbols in the
3205 // sense that they're preserved through all our LTO passes and only
3206 // strippable by the linker.
3208 // Additionally weak lang items have predetermined symbol names.
3209 if tcx.is_weak_lang_item(id) {
3210 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3212 if let Some(name) = weak_lang_items::link_name(attrs) {
3213 codegen_fn_attrs.export_name = Some(name);
3214 codegen_fn_attrs.link_name = Some(name);
3216 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3218 // Internal symbols to the standard library all have no_mangle semantics in
3219 // that they have defined symbol names present in the function name. This
3220 // also applies to weak symbols where they all have known symbol names.
3221 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3222 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3225 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3226 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3227 // intrinsic functions.
3228 if let Some(name) = &codegen_fn_attrs.link_name {
3229 if name.as_str().starts_with("llvm.") {
3230 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3237 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3238 /// applied to the method prototype.
3239 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3240 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
3241 if let ty::AssocItemContainer::ImplContainer(_) = impl_item.container {
3242 if let Some(trait_item) = impl_item.trait_item_def_id {
3244 .codegen_fn_attrs(trait_item)
3246 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3254 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3255 use rustc_ast::{Lit, LitIntType, LitKind};
3256 let meta_item_list = attr.meta_item_list();
3257 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3258 let sole_meta_list = match meta_item_list {
3259 Some([item]) => item.literal(),
3262 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3263 .note("the attribute requires exactly one argument")
3269 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3270 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3271 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3272 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3273 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3275 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3276 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3277 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3278 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3279 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3280 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3281 // about LINK.EXE failing.)
3282 if *ordinal <= u16::MAX as u128 {
3283 Some(*ordinal as u16)
3285 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3287 .struct_span_err(attr.span, &msg)
3288 .note("the value may not exceed `u16::MAX`")
3294 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3295 .note("an unsuffixed integer value, e.g., `1`, is expected")
3301 fn check_link_name_xor_ordinal(
3303 codegen_fn_attrs: &CodegenFnAttrs,
3304 inline_span: Option<Span>,
3306 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3309 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3310 if let Some(span) = inline_span {
3311 tcx.sess.span_err(span, msg);
3317 /// Checks the function annotated with `#[target_feature]` is not a safe
3318 /// trait method implementation, reporting an error if it is.
3319 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3320 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3321 let node = tcx.hir().get(hir_id);
3322 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3323 let parent_id = tcx.hir().get_parent_item(hir_id);
3324 let parent_item = tcx.hir().expect_item(parent_id);
3325 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3329 "`#[target_feature(..)]` cannot be applied to safe trait method",
3331 .span_label(attr_span, "cannot be applied to safe trait method")
3332 .span_label(tcx.def_span(id), "not an `unsafe` function")