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, Bounds, SizedByDefault};
18 use crate::check::intrinsic::intrinsic_operation_unsafety;
19 use crate::constrained_generic_params as cgp;
21 use crate::middle::resolve_lifetime as rl;
22 use crate::middle::weak_lang_items;
23 use rustc::hir::map::blocks::FnLikeNode;
24 use rustc::hir::map::Map;
25 use rustc::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
26 use rustc::mir::mono::Linkage;
27 use rustc::session::parse::feature_err;
29 use rustc::ty::query::Providers;
30 use rustc::ty::subst::GenericArgKind;
31 use rustc::ty::subst::{InternalSubsts, Subst};
32 use rustc::ty::util::Discr;
33 use rustc::ty::util::IntTypeExt;
34 use rustc::ty::{self, AdtKind, Const, DefIdTree, ToPolyTraitRef, Ty, TyCtxt, WithConstness};
35 use rustc::ty::{ReprOptions, ToPredicate};
36 use rustc_data_structures::captures::Captures;
37 use rustc_data_structures::fx::FxHashMap;
38 use rustc_errors::{struct_span_err, Applicability, StashKey};
40 use rustc_hir::def::{CtorKind, DefKind, Res};
41 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
42 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
43 use rustc_hir::{GenericParamKind, Node, Unsafety};
44 use rustc_span::symbol::{kw, sym, Symbol};
45 use rustc_span::{Span, DUMMY_SP};
46 use rustc_target::spec::abi;
48 use syntax::ast::{Ident, MetaItemKind};
49 use syntax::attr::{list_contains_name, mark_used, InlineAttr, OptimizeAttr};
51 use rustc_error_codes::*;
53 struct OnlySelfBounds(bool);
55 ///////////////////////////////////////////////////////////////////////////
58 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: DefId) {
59 tcx.hir().visit_item_likes_in_module(
61 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
65 pub fn provide(providers: &mut Providers<'_>) {
66 *providers = Providers {
70 predicates_defined_on,
71 explicit_predicates_of,
73 type_param_predicates,
82 collect_mod_item_types,
87 ///////////////////////////////////////////////////////////////////////////
89 /// Context specific to some particular item. This is what implements
90 /// `AstConv`. It has information about the predicates that are defined
91 /// on the trait. Unfortunately, this predicate information is
92 /// available in various different forms at various points in the
93 /// process. So we can't just store a pointer to e.g., the AST or the
94 /// parsed ty form, we have to be more flexible. To this end, the
95 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
96 /// `get_type_parameter_bounds` requests, drawing the information from
97 /// the AST (`hir::Generics`), recursively.
98 pub struct ItemCtxt<'tcx> {
103 ///////////////////////////////////////////////////////////////////////////
106 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
108 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
111 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
112 NestedVisitorMap::None
114 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
115 if let hir::TyKind::Infer = t.kind {
118 intravisit::walk_ty(self, t)
122 struct CollectItemTypesVisitor<'tcx> {
126 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
127 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
128 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
129 crate fn placeholder_type_error(
132 generics: &[hir::GenericParam<'_>],
133 placeholder_types: Vec<Span>,
136 if placeholder_types.is_empty() {
139 // This is the whitelist of possible parameter names that we might suggest.
140 let possible_names = ["T", "K", "L", "A", "B", "C"];
141 let used_names = generics
143 .filter_map(|p| match p.name {
144 hir::ParamName::Plain(ident) => Some(ident.name),
147 .collect::<Vec<_>>();
149 let type_name = possible_names
151 .find(|n| !used_names.contains(&Symbol::intern(n)))
152 .unwrap_or(&"ParamName");
154 let mut sugg: Vec<_> =
155 placeholder_types.iter().map(|sp| (*sp, type_name.to_string())).collect();
156 if generics.is_empty() {
157 sugg.push((span, format!("<{}>", type_name)));
158 } else if let Some(arg) = generics.iter().find(|arg| match arg.name {
159 hir::ParamName::Plain(Ident { name: kw::Underscore, .. }) => true,
162 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
163 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
164 sugg.push((arg.span, format!("{}", type_name)));
167 generics.iter().last().unwrap().span.shrink_to_hi(),
168 format!(", {}", type_name),
171 let mut err = bad_placeholder_type(tcx, placeholder_types);
173 err.multipart_suggestion(
174 "use type parameters instead",
176 Applicability::HasPlaceholders,
182 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
183 let (generics, suggest) = match &item.kind {
184 hir::ItemKind::Union(_, generics)
185 | hir::ItemKind::Enum(_, generics)
186 | hir::ItemKind::TraitAlias(generics, _)
187 | hir::ItemKind::Trait(_, _, generics, ..)
188 | hir::ItemKind::Impl { generics, .. }
189 | hir::ItemKind::Struct(_, generics) => (generics, true),
190 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
191 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
192 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
196 let mut visitor = PlaceholderHirTyCollector::default();
197 visitor.visit_item(item);
199 placeholder_type_error(tcx, generics.span, &generics.params[..], visitor.0, suggest);
202 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
203 type Map = Map<'tcx>;
205 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
206 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
209 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
210 convert_item(self.tcx, item.hir_id);
211 reject_placeholder_type_signatures_in_item(self.tcx, item);
212 intravisit::walk_item(self, item);
215 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
216 for param in generics.params {
218 hir::GenericParamKind::Lifetime { .. } => {}
219 hir::GenericParamKind::Type { default: Some(_), .. } => {
220 let def_id = self.tcx.hir().local_def_id(param.hir_id);
221 self.tcx.type_of(def_id);
223 hir::GenericParamKind::Type { .. } => {}
224 hir::GenericParamKind::Const { .. } => {
225 let def_id = self.tcx.hir().local_def_id(param.hir_id);
226 self.tcx.type_of(def_id);
230 intravisit::walk_generics(self, generics);
233 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
234 if let hir::ExprKind::Closure(..) = expr.kind {
235 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
236 self.tcx.generics_of(def_id);
237 self.tcx.type_of(def_id);
239 intravisit::walk_expr(self, expr);
242 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
243 convert_trait_item(self.tcx, trait_item.hir_id);
244 intravisit::walk_trait_item(self, trait_item);
247 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
248 convert_impl_item(self.tcx, impl_item.hir_id);
249 intravisit::walk_impl_item(self, impl_item);
253 ///////////////////////////////////////////////////////////////////////////
254 // Utility types and common code for the above passes.
256 fn bad_placeholder_type(
258 mut spans: Vec<Span>,
259 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
261 let mut err = struct_span_err!(
265 "the type placeholder `_` is not allowed within types on item signatures",
268 err.span_label(span, "not allowed in type signatures");
273 impl ItemCtxt<'tcx> {
274 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
275 ItemCtxt { tcx, item_def_id }
278 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
279 AstConv::ast_ty_to_ty(self, ast_ty)
283 impl AstConv<'tcx> for ItemCtxt<'tcx> {
284 fn tcx(&self) -> TyCtxt<'tcx> {
288 fn item_def_id(&self) -> Option<DefId> {
289 Some(self.item_def_id)
292 fn default_constness_for_trait_bounds(&self) -> ast::Constness {
293 // FIXME: refactor this into a method
297 .as_local_hir_id(self.item_def_id)
298 .expect("Non-local call to local provider is_const_fn");
300 let node = self.tcx.hir().get(hir_id);
301 if let Some(fn_like) = FnLikeNode::from_node(node) {
304 ast::Constness::NotConst
308 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
309 self.tcx.at(span).type_param_predicates((self.item_def_id, def_id))
312 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
316 fn allow_ty_infer(&self) -> bool {
320 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
321 self.tcx().sess.delay_span_bug(span, "bad placeholder type");
328 _: Option<&ty::GenericParamDef>,
330 ) -> &'tcx Const<'tcx> {
331 bad_placeholder_type(self.tcx(), vec![span]).emit();
333 self.tcx().consts.err
336 fn projected_ty_from_poly_trait_ref(
340 item_segment: &hir::PathSegment<'_>,
341 poly_trait_ref: ty::PolyTraitRef<'tcx>,
343 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
344 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
352 self.tcx().mk_projection(item_def_id, item_substs)
354 // There are no late-bound regions; we can just ignore the binder.
359 "cannot extract an associated type from a higher-ranked trait bound \
367 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
368 // Types in item signatures are not normalized to avoid undue dependencies.
372 fn set_tainted_by_errors(&self) {
373 // There's no obvious place to track this, so just let it go.
376 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
377 // There's no place to record types from signatures?
381 /// Returns the predicates defined on `item_def_id` of the form
382 /// `X: Foo` where `X` is the type parameter `def_id`.
383 fn type_param_predicates(
385 (item_def_id, def_id): (DefId, DefId),
386 ) -> ty::GenericPredicates<'_> {
389 // In the AST, bounds can derive from two places. Either
390 // written inline like `<T: Foo>` or in a where-clause like
393 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
394 let param_owner = tcx.hir().ty_param_owner(param_id);
395 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
396 let generics = tcx.generics_of(param_owner_def_id);
397 let index = generics.param_def_id_to_index[&def_id];
398 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
400 // Don't look for bounds where the type parameter isn't in scope.
402 if item_def_id == param_owner_def_id { None } else { tcx.generics_of(item_def_id).parent };
404 let mut result = parent
406 let icx = ItemCtxt::new(tcx, parent);
407 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
409 .unwrap_or_default();
410 let mut extend = None;
412 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
413 let ast_generics = match tcx.hir().get(item_hir_id) {
414 Node::TraitItem(item) => &item.generics,
416 Node::ImplItem(item) => &item.generics,
418 Node::Item(item) => {
420 ItemKind::Fn(.., ref generics, _)
421 | ItemKind::Impl { ref generics, .. }
422 | ItemKind::TyAlias(_, ref generics)
423 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
424 | ItemKind::Enum(_, ref generics)
425 | ItemKind::Struct(_, ref generics)
426 | ItemKind::Union(_, ref generics) => generics,
427 ItemKind::Trait(_, _, ref generics, ..) => {
428 // Implied `Self: Trait` and supertrait bounds.
429 if param_id == item_hir_id {
430 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
432 Some((identity_trait_ref.without_const().to_predicate(), item.span));
440 Node::ForeignItem(item) => match item.kind {
441 ForeignItemKind::Fn(_, _, ref generics) => generics,
448 let icx = ItemCtxt::new(tcx, item_def_id);
449 let extra_predicates = extend.into_iter().chain(
450 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
452 .filter(|(predicate, _)| match predicate {
453 ty::Predicate::Trait(ref data, _) => data.skip_binder().self_ty().is_param(index),
458 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
462 impl ItemCtxt<'tcx> {
463 /// Finds bounds from `hir::Generics`. This requires scanning through the
464 /// AST. We do this to avoid having to convert *all* the bounds, which
465 /// would create artificial cycles. Instead, we can only convert the
466 /// bounds for a type parameter `X` if `X::Foo` is used.
467 fn type_parameter_bounds_in_generics(
469 ast_generics: &'tcx hir::Generics<'tcx>,
470 param_id: hir::HirId,
472 only_self_bounds: OnlySelfBounds,
473 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
474 let constness = self.default_constness_for_trait_bounds();
475 let from_ty_params = ast_generics
478 .filter_map(|param| match param.kind {
479 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
482 .flat_map(|bounds| bounds.iter())
483 .flat_map(|b| predicates_from_bound(self, ty, b, constness));
485 let from_where_clauses = ast_generics
489 .filter_map(|wp| match *wp {
490 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
494 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
496 } else if !only_self_bounds.0 {
497 Some(self.to_ty(&bp.bounded_ty))
501 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
503 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b, constness));
505 from_ty_params.chain(from_where_clauses).collect()
509 /// Tests whether this is the AST for a reference to the type
510 /// parameter with ID `param_id`. We use this so as to avoid running
511 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
512 /// conversion of the type to avoid inducing unnecessary cycles.
513 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
514 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
516 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
517 def_id == tcx.hir().local_def_id(param_id)
526 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::HirId) {
527 let it = tcx.hir().expect_item(item_id);
528 debug!("convert: item {} with id {}", it.ident, it.hir_id);
529 let def_id = tcx.hir().local_def_id(item_id);
531 // These don't define types.
532 hir::ItemKind::ExternCrate(_)
533 | hir::ItemKind::Use(..)
534 | hir::ItemKind::Mod(_)
535 | hir::ItemKind::GlobalAsm(_) => {}
536 hir::ItemKind::ForeignMod(ref foreign_mod) => {
537 for item in foreign_mod.items {
538 let def_id = tcx.hir().local_def_id(item.hir_id);
539 tcx.generics_of(def_id);
541 tcx.predicates_of(def_id);
542 if let hir::ForeignItemKind::Fn(..) = item.kind {
547 hir::ItemKind::Enum(ref enum_definition, _) => {
548 tcx.generics_of(def_id);
550 tcx.predicates_of(def_id);
551 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
553 hir::ItemKind::Impl { .. } => {
554 tcx.generics_of(def_id);
556 tcx.impl_trait_ref(def_id);
557 tcx.predicates_of(def_id);
559 hir::ItemKind::Trait(..) => {
560 tcx.generics_of(def_id);
561 tcx.trait_def(def_id);
562 tcx.at(it.span).super_predicates_of(def_id);
563 tcx.predicates_of(def_id);
565 hir::ItemKind::TraitAlias(..) => {
566 tcx.generics_of(def_id);
567 tcx.at(it.span).super_predicates_of(def_id);
568 tcx.predicates_of(def_id);
570 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
571 tcx.generics_of(def_id);
573 tcx.predicates_of(def_id);
575 for f in struct_def.fields() {
576 let def_id = tcx.hir().local_def_id(f.hir_id);
577 tcx.generics_of(def_id);
579 tcx.predicates_of(def_id);
582 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
583 convert_variant_ctor(tcx, ctor_hir_id);
587 // Desugared from `impl Trait`, so visited by the function's return type.
588 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
590 hir::ItemKind::OpaqueTy(..)
591 | hir::ItemKind::TyAlias(..)
592 | hir::ItemKind::Static(..)
593 | hir::ItemKind::Const(..)
594 | hir::ItemKind::Fn(..) => {
595 tcx.generics_of(def_id);
597 tcx.predicates_of(def_id);
598 if let hir::ItemKind::Fn(..) = it.kind {
605 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
606 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
607 let def_id = tcx.hir().local_def_id(trait_item.hir_id);
608 tcx.generics_of(def_id);
610 match trait_item.kind {
611 hir::TraitItemKind::Const(..)
612 | hir::TraitItemKind::Type(_, Some(_))
613 | hir::TraitItemKind::Method(..) => {
615 if let hir::TraitItemKind::Method(..) = trait_item.kind {
620 hir::TraitItemKind::Type(_, None) => {}
623 tcx.predicates_of(def_id);
626 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
627 let def_id = tcx.hir().local_def_id(impl_item_id);
628 tcx.generics_of(def_id);
630 tcx.predicates_of(def_id);
631 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).kind {
636 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
637 let def_id = tcx.hir().local_def_id(ctor_id);
638 tcx.generics_of(def_id);
640 tcx.predicates_of(def_id);
643 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
644 let def = tcx.adt_def(def_id);
645 let repr_type = def.repr.discr_type();
646 let initial = repr_type.initial_discriminant(tcx);
647 let mut prev_discr = None::<Discr<'_>>;
649 // fill the discriminant values and field types
650 for variant in variants {
651 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
653 if let Some(ref e) = variant.disr_expr {
654 let expr_did = tcx.hir().local_def_id(e.hir_id);
655 def.eval_explicit_discr(tcx, expr_did)
656 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
659 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
662 format!("overflowed on value after {}", prev_discr.unwrap()),
665 "explicitly set `{} = {}` if that is desired outcome",
666 variant.ident, wrapped_discr
671 .unwrap_or(wrapped_discr),
674 for f in variant.data.fields() {
675 let def_id = tcx.hir().local_def_id(f.hir_id);
676 tcx.generics_of(def_id);
678 tcx.predicates_of(def_id);
681 // Convert the ctor, if any. This also registers the variant as
683 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
684 convert_variant_ctor(tcx, ctor_hir_id);
691 variant_did: Option<DefId>,
692 ctor_did: Option<DefId>,
694 discr: ty::VariantDiscr,
695 def: &hir::VariantData<'_>,
696 adt_kind: ty::AdtKind,
698 ) -> ty::VariantDef {
699 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
700 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
705 let fid = tcx.hir().local_def_id(f.hir_id);
706 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
707 if let Some(prev_span) = dup_span {
712 "field `{}` is already declared",
715 .span_label(f.span, "field already declared")
716 .span_label(prev_span, format!("`{}` first declared here", f.ident))
719 seen_fields.insert(f.ident.modern(), f.span);
725 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
729 let recovered = match def {
730 hir::VariantData::Struct(_, r) => *r,
740 CtorKind::from_hir(def),
747 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
750 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
751 let item = match tcx.hir().get(hir_id) {
752 Node::Item(item) => item,
756 let repr = ReprOptions::new(tcx, def_id);
757 let (kind, variants) = match item.kind {
758 ItemKind::Enum(ref def, _) => {
759 let mut distance_from_explicit = 0;
764 let variant_did = Some(tcx.hir().local_def_id(v.id));
766 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
768 let discr = if let Some(ref e) = v.disr_expr {
769 distance_from_explicit = 0;
770 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id))
772 ty::VariantDiscr::Relative(distance_from_explicit)
774 distance_from_explicit += 1;
789 (AdtKind::Enum, variants)
791 ItemKind::Struct(ref def, _) => {
792 let variant_did = None;
793 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
795 let variants = std::iter::once(convert_variant(
800 ty::VariantDiscr::Relative(0),
807 (AdtKind::Struct, variants)
809 ItemKind::Union(ref def, _) => {
810 let variant_did = None;
811 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
813 let variants = std::iter::once(convert_variant(
818 ty::VariantDiscr::Relative(0),
825 (AdtKind::Union, variants)
829 tcx.alloc_adt_def(def_id, kind, variants, repr)
832 /// Ensures that the super-predicates of the trait with a `DefId`
833 /// of `trait_def_id` are converted and stored. This also ensures that
834 /// the transitive super-predicates are converted.
835 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
836 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
837 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
839 let item = match tcx.hir().get(trait_hir_id) {
840 Node::Item(item) => item,
841 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
844 let (generics, bounds) = match item.kind {
845 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
846 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
847 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
850 let icx = ItemCtxt::new(tcx, trait_def_id);
852 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
853 let self_param_ty = tcx.types.self_param;
855 AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
857 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
859 // Convert any explicit superbounds in the where-clause,
860 // e.g., `trait Foo where Self: Bar`.
861 // In the case of trait aliases, however, we include all bounds in the where-clause,
862 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
863 // as one of its "superpredicates".
864 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
865 let superbounds2 = icx.type_parameter_bounds_in_generics(
869 OnlySelfBounds(!is_trait_alias),
872 // Combine the two lists to form the complete set of superbounds:
873 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
875 // Now require that immediate supertraits are converted,
876 // which will, in turn, reach indirect supertraits.
877 for &(pred, span) in superbounds {
878 debug!("superbound: {:?}", pred);
879 if let ty::Predicate::Trait(bound, _) = pred {
880 tcx.at(span).super_predicates_of(bound.def_id());
884 ty::GenericPredicates { parent: None, predicates: superbounds }
887 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
888 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
889 let item = tcx.hir().expect_item(hir_id);
891 let (is_auto, unsafety) = match item.kind {
892 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
893 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
894 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
897 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
898 if paren_sugar && !tcx.features().unboxed_closures {
902 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
903 which traits can use parenthetical notation",
905 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
909 let is_marker = tcx.has_attr(def_id, sym::marker);
910 let def_path_hash = tcx.def_path_hash(def_id);
911 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
915 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
916 struct LateBoundRegionsDetector<'tcx> {
918 outer_index: ty::DebruijnIndex,
919 has_late_bound_regions: Option<Span>,
922 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
923 type Map = Map<'tcx>;
925 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
926 NestedVisitorMap::None
929 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
930 if self.has_late_bound_regions.is_some() {
934 hir::TyKind::BareFn(..) => {
935 self.outer_index.shift_in(1);
936 intravisit::walk_ty(self, ty);
937 self.outer_index.shift_out(1);
939 _ => intravisit::walk_ty(self, ty),
943 fn visit_poly_trait_ref(
945 tr: &'tcx hir::PolyTraitRef<'tcx>,
946 m: hir::TraitBoundModifier,
948 if self.has_late_bound_regions.is_some() {
951 self.outer_index.shift_in(1);
952 intravisit::walk_poly_trait_ref(self, tr, m);
953 self.outer_index.shift_out(1);
956 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
957 if self.has_late_bound_regions.is_some() {
961 match self.tcx.named_region(lt.hir_id) {
962 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
963 Some(rl::Region::LateBound(debruijn, _, _))
964 | Some(rl::Region::LateBoundAnon(debruijn, _))
965 if debruijn < self.outer_index => {}
966 Some(rl::Region::LateBound(..))
967 | Some(rl::Region::LateBoundAnon(..))
968 | Some(rl::Region::Free(..))
970 self.has_late_bound_regions = Some(lt.span);
976 fn has_late_bound_regions<'tcx>(
978 generics: &'tcx hir::Generics<'tcx>,
979 decl: &'tcx hir::FnDecl<'tcx>,
981 let mut visitor = LateBoundRegionsDetector {
983 outer_index: ty::INNERMOST,
984 has_late_bound_regions: None,
986 for param in generics.params {
987 if let GenericParamKind::Lifetime { .. } = param.kind {
988 if tcx.is_late_bound(param.hir_id) {
989 return Some(param.span);
993 visitor.visit_fn_decl(decl);
994 visitor.has_late_bound_regions
998 Node::TraitItem(item) => match item.kind {
999 hir::TraitItemKind::Method(ref sig, _) => {
1000 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1004 Node::ImplItem(item) => match item.kind {
1005 hir::ImplItemKind::Method(ref sig, _) => {
1006 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1010 Node::ForeignItem(item) => match item.kind {
1011 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
1012 has_late_bound_regions(tcx, generics, fn_decl)
1016 Node::Item(item) => match item.kind {
1017 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1018 has_late_bound_regions(tcx, generics, &sig.decl)
1026 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
1029 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1031 let node = tcx.hir().get(hir_id);
1032 let parent_def_id = match node {
1034 | Node::TraitItem(_)
1037 | Node::Field(_) => {
1038 let parent_id = tcx.hir().get_parent_item(hir_id);
1039 Some(tcx.hir().local_def_id(parent_id))
1041 // FIXME(#43408) enable this always when we get lazy normalization.
1042 Node::AnonConst(_) => {
1043 // HACK(eddyb) this provides the correct generics when
1044 // `feature(const_generics)` is enabled, so that const expressions
1045 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1046 if tcx.features().const_generics {
1047 let parent_id = tcx.hir().get_parent_item(hir_id);
1048 Some(tcx.hir().local_def_id(parent_id))
1053 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1054 Some(tcx.closure_base_def_id(def_id))
1056 Node::Item(item) => match item.kind {
1057 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => impl_trait_fn,
1063 let mut opt_self = None;
1064 let mut allow_defaults = false;
1066 let no_generics = hir::Generics::empty();
1067 let ast_generics = match node {
1068 Node::TraitItem(item) => &item.generics,
1070 Node::ImplItem(item) => &item.generics,
1072 Node::Item(item) => {
1074 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl { ref generics, .. } => generics,
1076 ItemKind::TyAlias(_, ref generics)
1077 | ItemKind::Enum(_, ref generics)
1078 | ItemKind::Struct(_, ref generics)
1079 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1080 | ItemKind::Union(_, ref generics) => {
1081 allow_defaults = true;
1085 ItemKind::Trait(_, _, ref generics, ..)
1086 | ItemKind::TraitAlias(ref generics, ..) => {
1087 // Add in the self type parameter.
1089 // Something of a hack: use the node id for the trait, also as
1090 // the node id for the Self type parameter.
1091 let param_id = item.hir_id;
1093 opt_self = Some(ty::GenericParamDef {
1095 name: kw::SelfUpper,
1096 def_id: tcx.hir().local_def_id(param_id),
1097 pure_wrt_drop: false,
1098 kind: ty::GenericParamDefKind::Type {
1100 object_lifetime_default: rl::Set1::Empty,
1105 allow_defaults = true;
1113 Node::ForeignItem(item) => match item.kind {
1114 ForeignItemKind::Static(..) => &no_generics,
1115 ForeignItemKind::Fn(_, _, ref generics) => generics,
1116 ForeignItemKind::Type => &no_generics,
1122 let has_self = opt_self.is_some();
1123 let mut parent_has_self = false;
1124 let mut own_start = has_self as u32;
1125 let parent_count = parent_def_id.map_or(0, |def_id| {
1126 let generics = tcx.generics_of(def_id);
1127 assert_eq!(has_self, false);
1128 parent_has_self = generics.has_self;
1129 own_start = generics.count() as u32;
1130 generics.parent_count + generics.params.len()
1133 let mut params: Vec<_> = opt_self.into_iter().collect();
1135 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1136 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1137 name: param.name.ident().name,
1138 index: own_start + i as u32,
1139 def_id: tcx.hir().local_def_id(param.hir_id),
1140 pure_wrt_drop: param.pure_wrt_drop,
1141 kind: ty::GenericParamDefKind::Lifetime,
1144 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1146 // Now create the real type parameters.
1147 let type_start = own_start - has_self as u32 + params.len() as u32;
1149 params.extend(ast_generics.params.iter().filter_map(|param| {
1150 let kind = match param.kind {
1151 GenericParamKind::Type { ref default, synthetic, .. } => {
1152 if !allow_defaults && default.is_some() {
1153 if !tcx.features().default_type_parameter_fallback {
1155 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1159 "defaults for type parameters are only allowed in \
1160 `struct`, `enum`, `type`, or `trait` definitions."
1166 ty::GenericParamDefKind::Type {
1167 has_default: default.is_some(),
1168 object_lifetime_default: object_lifetime_defaults
1170 .map_or(rl::Set1::Empty, |o| o[i]),
1174 GenericParamKind::Const { .. } => ty::GenericParamDefKind::Const,
1178 let param_def = ty::GenericParamDef {
1179 index: type_start + i as u32,
1180 name: param.name.ident().name,
1181 def_id: tcx.hir().local_def_id(param.hir_id),
1182 pure_wrt_drop: param.pure_wrt_drop,
1189 // provide junk type parameter defs - the only place that
1190 // cares about anything but the length is instantiation,
1191 // and we don't do that for closures.
1192 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1193 let dummy_args = if gen.is_some() {
1194 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1196 &["<closure_kind>", "<closure_signature>"][..]
1199 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1200 index: type_start + i as u32,
1201 name: Symbol::intern(arg),
1203 pure_wrt_drop: false,
1204 kind: ty::GenericParamDefKind::Type {
1206 object_lifetime_default: rl::Set1::Empty,
1211 if let Some(upvars) = tcx.upvars(def_id) {
1212 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1213 ty::GenericParamDef {
1214 index: type_start + i,
1215 name: Symbol::intern("<upvar>"),
1217 pure_wrt_drop: false,
1218 kind: ty::GenericParamDefKind::Type {
1220 object_lifetime_default: rl::Set1::Empty,
1228 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1230 tcx.arena.alloc(ty::Generics {
1231 parent: parent_def_id,
1234 param_def_id_to_index,
1235 has_self: has_self || parent_has_self,
1236 has_late_bound_regions: has_late_bound_regions(tcx, node),
1240 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
1245 "associated types are not yet supported in inherent impls (see #8995)"
1250 fn infer_placeholder_type(
1253 body_id: hir::BodyId,
1257 let ty = tcx.diagnostic_only_typeck_tables_of(def_id).node_type(body_id.hir_id);
1259 // If this came from a free `const` or `static mut?` item,
1260 // then the user may have written e.g. `const A = 42;`.
1261 // In this case, the parser has stashed a diagnostic for
1262 // us to improve in typeck so we do that now.
1263 match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
1265 // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
1266 // We are typeck and have the real type, so remove that and suggest the actual type.
1267 err.suggestions.clear();
1268 err.span_suggestion(
1270 "provide a type for the item",
1271 format!("{}: {}", item_ident, ty),
1272 Applicability::MachineApplicable,
1277 let mut diag = bad_placeholder_type(tcx, vec![span]);
1278 if ty != tcx.types.err {
1279 diag.span_suggestion(
1281 "replace `_` with the correct type",
1283 Applicability::MaybeIncorrect,
1293 fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1296 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1298 let icx = ItemCtxt::new(tcx, def_id);
1300 match tcx.hir().get(hir_id) {
1301 Node::TraitItem(item) => match item.kind {
1302 TraitItemKind::Method(..) => {
1303 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1304 tcx.mk_fn_def(def_id, substs)
1306 TraitItemKind::Const(ref ty, body_id) => body_id
1307 .and_then(|body_id| {
1308 if is_suggestable_infer_ty(ty) {
1309 Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
1314 .unwrap_or_else(|| icx.to_ty(ty)),
1315 TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1316 TraitItemKind::Type(_, None) => {
1317 span_bug!(item.span, "associated type missing default");
1321 Node::ImplItem(item) => match item.kind {
1322 ImplItemKind::Method(..) => {
1323 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1324 tcx.mk_fn_def(def_id, substs)
1326 ImplItemKind::Const(ref ty, body_id) => {
1327 if is_suggestable_infer_ty(ty) {
1328 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1333 ImplItemKind::OpaqueTy(_) => {
1334 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1335 report_assoc_ty_on_inherent_impl(tcx, item.span);
1338 find_opaque_ty_constraints(tcx, def_id)
1340 ImplItemKind::TyAlias(ref ty) => {
1341 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1342 report_assoc_ty_on_inherent_impl(tcx, item.span);
1349 Node::Item(item) => {
1351 ItemKind::Static(ref ty, .., body_id) | ItemKind::Const(ref ty, body_id) => {
1352 if is_suggestable_infer_ty(ty) {
1353 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1358 ItemKind::TyAlias(ref self_ty, _) | ItemKind::Impl { ref self_ty, .. } => {
1361 ItemKind::Fn(..) => {
1362 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1363 tcx.mk_fn_def(def_id, substs)
1365 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1366 let def = tcx.adt_def(def_id);
1367 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1368 tcx.mk_adt(def, substs)
1370 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: None, .. }) => {
1371 find_opaque_ty_constraints(tcx, def_id)
1373 // Opaque types desugared from `impl Trait`.
1374 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(owner), .. }) => {
1375 tcx.typeck_tables_of(owner)
1376 .concrete_opaque_types
1378 .map(|opaque| opaque.concrete_type)
1379 .unwrap_or_else(|| {
1380 // This can occur if some error in the
1381 // owner fn prevented us from populating
1382 // the `concrete_opaque_types` table.
1383 tcx.sess.delay_span_bug(
1386 "owner {:?} has no opaque type for {:?} in its tables",
1394 | ItemKind::TraitAlias(..)
1396 | ItemKind::ForeignMod(..)
1397 | ItemKind::GlobalAsm(..)
1398 | ItemKind::ExternCrate(..)
1399 | ItemKind::Use(..) => {
1402 "compute_type_of_item: unexpected item type: {:?}",
1409 Node::ForeignItem(foreign_item) => match foreign_item.kind {
1410 ForeignItemKind::Fn(..) => {
1411 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1412 tcx.mk_fn_def(def_id, substs)
1414 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1415 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1418 Node::Ctor(&ref def) | Node::Variant(hir::Variant { data: ref def, .. }) => match *def {
1419 VariantData::Unit(..) | VariantData::Struct(..) => {
1420 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1422 VariantData::Tuple(..) => {
1423 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1424 tcx.mk_fn_def(def_id, substs)
1428 Node::Field(field) => icx.to_ty(&field.ty),
1430 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) => {
1432 return tcx.typeck_tables_of(def_id).node_type(hir_id);
1435 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1436 tcx.mk_closure(def_id, substs)
1439 Node::AnonConst(_) => {
1440 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1442 Node::Ty(&hir::Ty { kind: hir::TyKind::Array(_, ref constant), .. })
1443 | Node::Ty(&hir::Ty { kind: hir::TyKind::Typeof(ref constant), .. })
1444 | Node::Expr(&hir::Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1445 if constant.hir_id == hir_id =>
1450 Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => {
1451 tcx.adt_def(tcx.hir().get_parent_did(hir_id)).repr.discr_type().to_ty(tcx)
1454 Node::Ty(&hir::Ty { kind: hir::TyKind::Path(_), .. })
1455 | Node::Expr(&hir::Expr { kind: ExprKind::Struct(..), .. })
1456 | Node::Expr(&hir::Expr { kind: ExprKind::Path(_), .. })
1457 | Node::TraitRef(..) => {
1458 let path = match parent_node {
1460 kind: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1463 | Node::Expr(&hir::Expr {
1464 kind: ExprKind::Path(QPath::Resolved(_, ref path)),
1466 }) => Some(&**path),
1467 Node::Expr(&hir::Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
1468 if let QPath::Resolved(_, ref path) = **path {
1474 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
1478 if let Some(path) = path {
1479 let arg_index = path
1482 .filter_map(|seg| seg.args.as_ref())
1483 .map(|generic_args| generic_args.args.as_ref())
1486 .filter(|arg| arg.is_const())
1488 .filter(|(_, arg)| arg.id() == hir_id)
1489 .map(|(index, _)| index)
1492 .unwrap_or_else(|| {
1493 bug!("no arg matching AnonConst in path");
1496 // We've encountered an `AnonConst` in some path, so we need to
1497 // figure out which generic parameter it corresponds to and return
1498 // the relevant type.
1499 let generics = match path.res {
1500 Res::Def(DefKind::Ctor(..), def_id) => {
1501 tcx.generics_of(tcx.parent(def_id).unwrap())
1503 Res::Def(_, def_id) => tcx.generics_of(def_id),
1504 Res::Err => return tcx.types.err,
1506 tcx.sess.delay_span_bug(
1508 &format!("unexpected const parent path def {:?}", res,),
1510 return tcx.types.err;
1518 if let ty::GenericParamDefKind::Const = param.kind {
1525 .map(|param| tcx.type_of(param.def_id))
1526 // This is no generic parameter associated with the arg. This is
1527 // probably from an extra arg where one is not needed.
1528 .unwrap_or(tcx.types.err)
1530 tcx.sess.delay_span_bug(
1532 &format!("unexpected const parent path {:?}", parent_node,),
1534 return tcx.types.err;
1539 tcx.sess.delay_span_bug(
1541 &format!("unexpected const parent in type_of_def_id(): {:?}", x),
1548 Node::GenericParam(param) => match ¶m.kind {
1549 hir::GenericParamKind::Type { default: Some(ref ty), .. } => icx.to_ty(ty),
1550 hir::GenericParamKind::Const { ty: ref hir_ty, .. } => {
1551 let ty = icx.to_ty(hir_ty);
1552 if !tcx.features().const_compare_raw_pointers {
1553 let err = match ty.peel_refs().kind {
1554 ty::FnPtr(_) => Some("function pointers"),
1555 ty::RawPtr(_) => Some("raw pointers"),
1558 if let Some(unsupported_type) = err {
1560 &tcx.sess.parse_sess,
1561 sym::const_compare_raw_pointers,
1564 "using {} as const generic parameters is unstable",
1571 if traits::search_for_structural_match_violation(param.hir_id, param.span, tcx, ty)
1578 "the types of const generic parameters must derive `PartialEq` and `Eq`",
1582 format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
1588 x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
1592 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1597 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1598 use rustc_hir::{ImplItem, Item, TraitItem};
1600 debug!("find_opaque_ty_constraints({:?})", def_id);
1602 struct ConstraintLocator<'tcx> {
1605 // (first found type span, actual type, mapping from the opaque type's generic
1606 // parameters to the concrete type's generic parameters)
1608 // The mapping is an index for each use site of a generic parameter in the concrete type
1610 // The indices index into the generic parameters on the opaque type.
1611 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1614 impl ConstraintLocator<'tcx> {
1615 fn check(&mut self, def_id: DefId) {
1616 // Don't try to check items that cannot possibly constrain the type.
1617 if !self.tcx.has_typeck_tables(def_id) {
1619 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1620 self.def_id, def_id,
1624 let ty = self.tcx.typeck_tables_of(def_id).concrete_opaque_types.get(&self.def_id);
1625 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1627 "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1628 self.def_id, def_id, ty,
1631 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1632 let span = self.tcx.def_span(def_id);
1633 // used to quickly look up the position of a generic parameter
1634 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1635 // Skipping binder is ok, since we only use this to find generic parameters and
1637 for (idx, subst) in substs.iter().enumerate() {
1638 if let GenericArgKind::Type(ty) = subst.unpack() {
1639 if let ty::Param(p) = ty.kind {
1640 if index_map.insert(p, idx).is_some() {
1641 // There was already an entry for `p`, meaning a generic parameter
1643 self.tcx.sess.span_err(
1646 "defining opaque type use restricts opaque \
1647 type by using the generic parameter `{}` twice",
1654 self.tcx.sess.delay_span_bug(
1657 "non-defining opaque ty use in defining scope: {:?}, {:?}",
1658 concrete_type, substs,
1664 // Compute the index within the opaque type for each generic parameter used in
1665 // the concrete type.
1666 let indices = concrete_type
1667 .subst(self.tcx, substs)
1669 .filter_map(|t| match &t.kind {
1670 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1674 let is_param = |ty: Ty<'_>| match ty.kind {
1675 ty::Param(_) => true,
1678 let bad_substs: Vec<_> =
1679 substs.types().enumerate().filter(|(_, ty)| !is_param(ty)).collect();
1680 if !bad_substs.is_empty() {
1681 let identity_substs = InternalSubsts::identity_for_item(self.tcx, self.def_id);
1682 for (i, bad_subst) in bad_substs {
1683 self.tcx.sess.span_err(
1686 "defining opaque type use does not fully define opaque type: \
1687 generic parameter `{}` is specified as concrete type `{}`",
1688 identity_substs.type_at(i),
1693 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1694 let mut ty = concrete_type.walk().fuse();
1695 let mut p_ty = prev_ty.walk().fuse();
1696 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.kind, &p.kind) {
1697 // Type parameters are equal to any other type parameter for the purpose of
1698 // concrete type equality, as it is possible to obtain the same type just
1699 // by passing matching parameters to a function.
1700 (ty::Param(_), ty::Param(_)) => true,
1703 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1704 debug!("find_opaque_ty_constraints: span={:?}", span);
1705 // Found different concrete types for the opaque type.
1706 let mut err = self.tcx.sess.struct_span_err(
1708 "concrete type differs from previous defining opaque type use",
1712 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1714 err.span_note(prev_span, "previous use here");
1716 } else if indices != *prev_indices {
1717 // Found "same" concrete types, but the generic parameter order differs.
1718 let mut err = self.tcx.sess.struct_span_err(
1720 "concrete type's generic parameters differ from previous defining use",
1722 use std::fmt::Write;
1723 let mut s = String::new();
1724 write!(s, "expected [").unwrap();
1725 let list = |s: &mut String, indices: &Vec<usize>| {
1726 let mut indices = indices.iter().cloned();
1727 if let Some(first) = indices.next() {
1728 write!(s, "`{}`", substs[first]).unwrap();
1730 write!(s, ", `{}`", substs[i]).unwrap();
1734 list(&mut s, prev_indices);
1735 write!(s, "], got [").unwrap();
1736 list(&mut s, &indices);
1737 write!(s, "]").unwrap();
1738 err.span_label(span, s);
1739 err.span_note(prev_span, "previous use here");
1743 self.found = Some((span, concrete_type, indices));
1747 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
1748 self.def_id, def_id,
1754 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1755 type Map = Map<'tcx>;
1757 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<'_, Self::Map> {
1758 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1760 fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
1761 debug!("find_existential_constraints: visiting {:?}", it);
1762 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1763 // The opaque type itself or its children are not within its reveal scope.
1764 if def_id != self.def_id {
1766 intravisit::walk_item(self, it);
1769 fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
1770 debug!("find_existential_constraints: visiting {:?}", it);
1771 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1772 // The opaque type itself or its children are not within its reveal scope.
1773 if def_id != self.def_id {
1775 intravisit::walk_impl_item(self, it);
1778 fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
1779 debug!("find_existential_constraints: visiting {:?}", it);
1780 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1782 intravisit::walk_trait_item(self, it);
1786 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1787 let scope = tcx.hir().get_defining_scope(hir_id);
1788 let mut locator = ConstraintLocator { def_id, tcx, found: None };
1790 debug!("find_opaque_ty_constraints: scope={:?}", scope);
1792 if scope == hir::CRATE_HIR_ID {
1793 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1795 debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
1796 match tcx.hir().get(scope) {
1797 // We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
1798 // This allows our visitor to process the defining item itself, causing
1799 // it to pick up any 'sibling' defining uses.
1801 // For example, this code:
1804 // type Blah = impl Debug;
1805 // let my_closure = || -> Blah { true };
1809 // requires us to explicitly process `foo()` in order
1810 // to notice the defining usage of `Blah`.
1811 Node::Item(ref it) => locator.visit_item(it),
1812 Node::ImplItem(ref it) => locator.visit_impl_item(it),
1813 Node::TraitItem(ref it) => locator.visit_trait_item(it),
1814 other => bug!("{:?} is not a valid scope for an opaque type item", other),
1818 match locator.found {
1819 Some((_, ty, _)) => ty,
1821 let span = tcx.def_span(def_id);
1822 tcx.sess.span_err(span, "could not find defining uses");
1828 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1831 .filter_map(|arg| match arg {
1832 hir::GenericArg::Type(ty) => Some(ty),
1835 .any(is_suggestable_infer_ty)
1838 /// Whether `ty` is a type with `_` placeholders that can be infered. Used in diagnostics only to
1839 /// use inference to provide suggestions for the appropriate type if possible.
1840 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1844 Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
1845 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1846 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1847 Def(_, generic_args) => are_suggestable_generic_args(generic_args),
1848 Path(hir::QPath::TypeRelative(ty, segment)) => {
1849 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.generic_args().args)
1851 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1852 ty_opt.map_or(false, is_suggestable_infer_ty)
1855 .any(|segment| are_suggestable_generic_args(segment.generic_args().args))
1861 pub fn get_infer_ret_ty(output: &'hir hir::FunctionRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1862 if let hir::FunctionRetTy::Return(ref ty) = output {
1863 if is_suggestable_infer_ty(ty) {
1870 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1871 use rustc_hir::Node::*;
1874 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1876 let icx = ItemCtxt::new(tcx, def_id);
1878 match tcx.hir().get(hir_id) {
1879 TraitItem(hir::TraitItem {
1880 kind: TraitItemKind::Method(sig, TraitMethod::Provided(_)),
1885 | ImplItem(hir::ImplItem { kind: ImplItemKind::Method(sig, _), ident, generics, .. })
1886 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1887 match get_infer_ret_ty(&sig.decl.output) {
1889 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1890 let mut visitor = PlaceholderHirTyCollector::default();
1891 visitor.visit_ty(ty);
1892 let mut diag = bad_placeholder_type(tcx, visitor.0);
1893 let ret_ty = fn_sig.output();
1894 if ret_ty != tcx.types.err {
1895 diag.span_suggestion(
1897 "replace with the correct return type",
1899 Applicability::MaybeIncorrect,
1903 ty::Binder::bind(fn_sig)
1905 None => AstConv::ty_of_fn(
1907 sig.header.unsafety,
1910 &generics.params[..],
1916 TraitItem(hir::TraitItem {
1917 kind: TraitItemKind::Method(FnSig { header, decl }, _),
1921 }) => AstConv::ty_of_fn(
1926 &generics.params[..],
1930 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(ref fn_decl, _, _), .. }) => {
1931 let abi = tcx.hir().get_foreign_abi(hir_id);
1932 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1935 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1936 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1938 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1939 ty::Binder::bind(tcx.mk_fn_sig(
1943 hir::Unsafety::Normal,
1948 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1949 // Closure signatures are not like other function
1950 // signatures and cannot be accessed through `fn_sig`. For
1951 // example, a closure signature excludes the `self`
1952 // argument. In any case they are embedded within the
1953 // closure type as part of the `ClosureSubsts`.
1956 // the signature of a closure, you should use the
1957 // `closure_sig` method on the `ClosureSubsts`:
1959 // closure_substs.sig(def_id, tcx)
1961 // or, inside of an inference context, you can use
1963 // infcx.closure_sig(def_id, closure_substs)
1964 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1968 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1973 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1974 let icx = ItemCtxt::new(tcx, def_id);
1976 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1977 match tcx.hir().expect_item(hir_id).kind {
1978 hir::ItemKind::Impl { ref of_trait, .. } => of_trait.as_ref().map(|ast_trait_ref| {
1979 let selfty = tcx.type_of(def_id);
1980 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1986 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1987 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1988 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1989 let item = tcx.hir().expect_item(hir_id);
1991 hir::ItemKind::Impl { polarity: hir::ImplPolarity::Negative, .. } => {
1992 if is_rustc_reservation {
1993 tcx.sess.span_err(item.span, "reservation impls can't be negative");
1995 ty::ImplPolarity::Negative
1997 hir::ItemKind::Impl { polarity: hir::ImplPolarity::Positive, of_trait: None, .. } => {
1998 if is_rustc_reservation {
1999 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2001 ty::ImplPolarity::Positive
2003 hir::ItemKind::Impl {
2004 polarity: hir::ImplPolarity::Positive, of_trait: Some(_), ..
2006 if is_rustc_reservation {
2007 ty::ImplPolarity::Reservation
2009 ty::ImplPolarity::Positive
2012 ref item => bug!("impl_polarity: {:?} not an impl", item),
2016 /// Returns the early-bound lifetimes declared in this generics
2017 /// listing. For anything other than fns/methods, this is just all
2018 /// the lifetimes that are declared. For fns or methods, we have to
2019 /// screen out those that do not appear in any where-clauses etc using
2020 /// `resolve_lifetime::early_bound_lifetimes`.
2021 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2023 generics: &'a hir::Generics<'a>,
2024 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2025 generics.params.iter().filter(move |param| match param.kind {
2026 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
2031 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2032 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2033 /// inferred constraints concerning which regions outlive other regions.
2034 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2035 debug!("predicates_defined_on({:?})", def_id);
2036 let mut result = tcx.explicit_predicates_of(def_id);
2037 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2038 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2039 if !inferred_outlives.is_empty() {
2041 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2042 def_id, inferred_outlives,
2044 if result.predicates.is_empty() {
2045 result.predicates = inferred_outlives;
2047 result.predicates = tcx
2049 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2052 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2056 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2057 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2058 /// `Self: Trait` predicates for traits.
2059 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2060 let mut result = tcx.predicates_defined_on(def_id);
2062 if tcx.is_trait(def_id) {
2063 // For traits, add `Self: Trait` predicate. This is
2064 // not part of the predicates that a user writes, but it
2065 // is something that one must prove in order to invoke a
2066 // method or project an associated type.
2068 // In the chalk setup, this predicate is not part of the
2069 // "predicates" for a trait item. But it is useful in
2070 // rustc because if you directly (e.g.) invoke a trait
2071 // method like `Trait::method(...)`, you must naturally
2072 // prove that the trait applies to the types that were
2073 // used, and adding the predicate into this list ensures
2074 // that this is done.
2075 let span = tcx.def_span(def_id);
2077 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2078 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(),
2082 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2086 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2087 /// N.B., this does not include any implied/inferred constraints.
2088 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2089 use rustc_data_structures::fx::FxHashSet;
2092 debug!("explicit_predicates_of(def_id={:?})", def_id);
2094 /// A data structure with unique elements, which preserves order of insertion.
2095 /// Preserving the order of insertion is important here so as not to break
2096 /// compile-fail UI tests.
2097 // FIXME(eddyb) just use `IndexSet` from `indexmap`.
2098 struct UniquePredicates<'tcx> {
2099 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
2100 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
2103 impl<'tcx> UniquePredicates<'tcx> {
2105 UniquePredicates { predicates: vec![], uniques: FxHashSet::default() }
2108 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
2109 if self.uniques.insert(value) {
2110 self.predicates.push(value);
2114 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
2121 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
2122 let node = tcx.hir().get(hir_id);
2124 let mut is_trait = None;
2125 let mut is_default_impl_trait = None;
2127 let icx = ItemCtxt::new(tcx, def_id);
2128 let constness = icx.default_constness_for_trait_bounds();
2130 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2132 let mut predicates = UniquePredicates::new();
2134 let ast_generics = match node {
2135 Node::TraitItem(item) => &item.generics,
2137 Node::ImplItem(item) => match item.kind {
2138 ImplItemKind::OpaqueTy(ref bounds) => {
2139 ty::print::with_no_queries(|| {
2140 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2141 let opaque_ty = tcx.mk_opaque(def_id, substs);
2143 "explicit_predicates_of({:?}): created opaque type {:?}",
2147 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2148 let bounds = AstConv::compute_bounds(
2152 SizedByDefault::Yes,
2153 tcx.def_span(def_id),
2156 predicates.extend(bounds.predicates(tcx, opaque_ty));
2160 _ => &item.generics,
2163 Node::Item(item) => {
2165 ItemKind::Impl { defaultness, ref generics, .. } => {
2166 if defaultness.is_default() {
2167 is_default_impl_trait = tcx.impl_trait_ref(def_id);
2171 ItemKind::Fn(.., ref generics, _)
2172 | ItemKind::TyAlias(_, ref generics)
2173 | ItemKind::Enum(_, ref generics)
2174 | ItemKind::Struct(_, ref generics)
2175 | ItemKind::Union(_, ref generics) => generics,
2177 ItemKind::Trait(_, _, ref generics, .., items) => {
2178 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
2181 ItemKind::TraitAlias(ref generics, _) => {
2182 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &[]));
2185 ItemKind::OpaqueTy(OpaqueTy {
2191 let bounds_predicates = ty::print::with_no_queries(|| {
2192 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2193 let opaque_ty = tcx.mk_opaque(def_id, substs);
2195 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2196 let bounds = AstConv::compute_bounds(
2200 SizedByDefault::Yes,
2201 tcx.def_span(def_id),
2204 bounds.predicates(tcx, opaque_ty)
2206 if impl_trait_fn.is_some() {
2208 return ty::GenericPredicates {
2210 predicates: tcx.arena.alloc_from_iter(bounds_predicates),
2213 // named opaque types
2214 predicates.extend(bounds_predicates);
2223 Node::ForeignItem(item) => match item.kind {
2224 ForeignItemKind::Static(..) => NO_GENERICS,
2225 ForeignItemKind::Fn(_, _, ref generics) => generics,
2226 ForeignItemKind::Type => NO_GENERICS,
2232 let generics = tcx.generics_of(def_id);
2233 let parent_count = generics.parent_count as u32;
2234 let has_own_self = generics.has_self && parent_count == 0;
2236 // Below we'll consider the bounds on the type parameters (including `Self`)
2237 // and the explicit where-clauses, but to get the full set of predicates
2238 // on a trait we need to add in the supertrait bounds and bounds found on
2239 // associated types.
2240 if let Some((_trait_ref, _)) = is_trait {
2241 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2244 // In default impls, we can assume that the self type implements
2245 // the trait. So in:
2247 // default impl Foo for Bar { .. }
2249 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2250 // (see below). Recall that a default impl is not itself an impl, but rather a
2251 // set of defaults that can be incorporated into another impl.
2252 if let Some(trait_ref) = is_default_impl_trait {
2254 trait_ref.to_poly_trait_ref().without_const().to_predicate(),
2255 tcx.def_span(def_id),
2259 // Collect the region predicates that were declared inline as
2260 // well. In the case of parameters declared on a fn or method, we
2261 // have to be careful to only iterate over early-bound regions.
2262 let mut index = parent_count + has_own_self as u32;
2263 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2264 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2265 def_id: tcx.hir().local_def_id(param.hir_id),
2267 name: param.name.ident().name,
2272 GenericParamKind::Lifetime { .. } => {
2273 param.bounds.iter().for_each(|bound| match bound {
2274 hir::GenericBound::Outlives(lt) => {
2275 let bound = AstConv::ast_region_to_region(&icx, <, None);
2276 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2277 predicates.push((outlives.to_predicate(), lt.span));
2286 // Collect the predicates that were written inline by the user on each
2287 // type parameter (e.g., `<T: Foo>`).
2288 for param in ast_generics.params {
2289 if let GenericParamKind::Type { .. } = param.kind {
2290 let name = param.name.ident().name;
2291 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2294 let sized = SizedByDefault::Yes;
2295 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2296 predicates.extend(bounds.predicates(tcx, param_ty));
2300 // Add in the bounds that appear in the where-clause.
2301 let where_clause = &ast_generics.where_clause;
2302 for predicate in where_clause.predicates {
2304 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2305 let ty = icx.to_ty(&bound_pred.bounded_ty);
2307 // Keep the type around in a dummy predicate, in case of no bounds.
2308 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2309 // is still checked for WF.
2310 if bound_pred.bounds.is_empty() {
2311 if let ty::Param(_) = ty.kind {
2312 // This is a `where T:`, which can be in the HIR from the
2313 // transformation that moves `?Sized` to `T`'s declaration.
2314 // We can skip the predicate because type parameters are
2315 // trivially WF, but also we *should*, to avoid exposing
2316 // users who never wrote `where Type:,` themselves, to
2317 // compiler/tooling bugs from not handling WF predicates.
2319 let span = bound_pred.bounded_ty.span;
2320 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2322 ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)),
2328 for bound in bound_pred.bounds.iter() {
2330 &hir::GenericBound::Trait(ref poly_trait_ref, modifier) => {
2331 let constness = match modifier {
2332 hir::TraitBoundModifier::MaybeConst => ast::Constness::NotConst,
2333 hir::TraitBoundModifier::None => constness,
2334 hir::TraitBoundModifier::Maybe => bug!("this wasn't handled"),
2337 let mut bounds = Bounds::default();
2338 let _ = AstConv::instantiate_poly_trait_ref(
2345 predicates.extend(bounds.predicates(tcx, ty));
2348 &hir::GenericBound::Outlives(ref lifetime) => {
2349 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2350 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2351 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2357 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2358 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2359 predicates.extend(region_pred.bounds.iter().map(|bound| {
2360 let (r2, span) = match bound {
2361 hir::GenericBound::Outlives(lt) => {
2362 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2366 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2368 (ty::Predicate::RegionOutlives(pred), span)
2372 &hir::WherePredicate::EqPredicate(..) => {
2378 // Add predicates from associated type bounds.
2379 if let Some((self_trait_ref, trait_items)) = is_trait {
2380 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2381 associated_item_predicates(tcx, def_id, self_trait_ref, trait_item_ref)
2385 let mut predicates = predicates.predicates;
2387 // Subtle: before we store the predicates into the tcx, we
2388 // sort them so that predicates like `T: Foo<Item=U>` come
2389 // before uses of `U`. This avoids false ambiguity errors
2390 // in trait checking. See `setup_constraining_predicates`
2392 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2393 let self_ty = tcx.type_of(def_id);
2394 let trait_ref = tcx.impl_trait_ref(def_id);
2395 cgp::setup_constraining_predicates(
2399 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2403 let result = ty::GenericPredicates {
2404 parent: generics.parent,
2405 predicates: tcx.arena.alloc_from_iter(predicates),
2407 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2411 fn associated_item_predicates(
2414 self_trait_ref: ty::TraitRef<'tcx>,
2415 trait_item_ref: &hir::TraitItemRef,
2416 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2417 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2418 let item_def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
2419 let bounds = match trait_item.kind {
2420 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2421 _ => return Vec::new(),
2424 let is_gat = !tcx.generics_of(item_def_id).params.is_empty();
2426 let mut had_error = false;
2428 let mut unimplemented_error = |arg_kind: &str| {
2433 &format!("{}-generic associated types are not yet implemented", arg_kind),
2435 .note("for more information, see https://github.com/rust-lang/rust/issues/44265")
2441 let mk_bound_param = |param: &ty::GenericParamDef, _: &_| {
2443 ty::GenericParamDefKind::Lifetime => tcx
2444 .mk_region(ty::RegionKind::ReLateBound(
2446 ty::BoundRegion::BrNamed(param.def_id, param.name),
2449 // FIXME(generic_associated_types): Use bound types and constants
2450 // once they are handled by the trait system.
2451 ty::GenericParamDefKind::Type { .. } => {
2452 unimplemented_error("type");
2453 tcx.types.err.into()
2455 ty::GenericParamDefKind::Const => {
2456 unimplemented_error("const");
2457 tcx.consts.err.into()
2462 let bound_substs = if is_gat {
2465 // trait X<'a, B, const C: usize> {
2466 // type T<'d, E, const F: usize>: Default;
2469 // We need to create predicates on the trait:
2471 // for<'d, E, const F: usize>
2472 // <Self as X<'a, B, const C: usize>>::T<'d, E, const F: usize>: Sized + Default
2474 // We substitute escaping bound parameters for the generic
2475 // arguments to the associated type which are then bound by
2476 // the `Binder` around the the predicate.
2478 // FIXME(generic_associated_types): Currently only lifetimes are handled.
2479 self_trait_ref.substs.extend_to(tcx, item_def_id, mk_bound_param)
2481 self_trait_ref.substs
2484 let assoc_ty = tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id), bound_substs);
2486 let bounds = AstConv::compute_bounds(
2487 &ItemCtxt::new(tcx, def_id),
2490 SizedByDefault::Yes,
2494 let predicates = bounds.predicates(tcx, assoc_ty);
2497 // We use shifts to get the regions that we're substituting to
2498 // be bound by the binders in the `Predicate`s rather that
2500 let shifted_in = ty::fold::shift_vars(tcx, &predicates, 1);
2501 let substituted = shifted_in.subst(tcx, bound_substs);
2502 ty::fold::shift_out_vars(tcx, &substituted, 1)
2508 /// Converts a specific `GenericBound` from the AST into a set of
2509 /// predicates that apply to the self type. A vector is returned
2510 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2511 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2512 /// and `<T as Bar>::X == i32`).
2513 fn predicates_from_bound<'tcx>(
2514 astconv: &dyn AstConv<'tcx>,
2516 bound: &'tcx hir::GenericBound<'tcx>,
2517 constness: ast::Constness,
2518 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2520 hir::GenericBound::Trait(ref tr, modifier) => {
2521 let constness = match modifier {
2522 hir::TraitBoundModifier::Maybe => return vec![],
2523 hir::TraitBoundModifier::MaybeConst => ast::Constness::NotConst,
2524 hir::TraitBoundModifier::None => constness,
2527 let mut bounds = Bounds::default();
2528 let _ = astconv.instantiate_poly_trait_ref(tr, constness, param_ty, &mut bounds);
2529 bounds.predicates(astconv.tcx(), param_ty)
2531 hir::GenericBound::Outlives(ref lifetime) => {
2532 let region = astconv.ast_region_to_region(lifetime, None);
2533 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2534 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2539 fn compute_sig_of_foreign_fn_decl<'tcx>(
2542 decl: &'tcx hir::FnDecl<'tcx>,
2544 ) -> ty::PolyFnSig<'tcx> {
2545 let unsafety = if abi == abi::Abi::RustIntrinsic {
2546 intrinsic_operation_unsafety(&tcx.item_name(def_id).as_str())
2548 hir::Unsafety::Unsafe
2550 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl, &[], None);
2552 // Feature gate SIMD types in FFI, since I am not sure that the
2553 // ABIs are handled at all correctly. -huonw
2554 if abi != abi::Abi::RustIntrinsic
2555 && abi != abi::Abi::PlatformIntrinsic
2556 && !tcx.features().simd_ffi
2558 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2564 "use of SIMD type `{}` in FFI is highly experimental and \
2565 may result in invalid code",
2566 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2569 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2573 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2576 if let hir::FunctionRetTy::Return(ref ty) = decl.output {
2577 check(&ty, *fty.output().skip_binder())
2584 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2585 match tcx.hir().get_if_local(def_id) {
2586 Some(Node::ForeignItem(..)) => true,
2588 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2592 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2593 match tcx.hir().get_if_local(def_id) {
2594 Some(Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. }))
2595 | Some(Node::ForeignItem(&hir::ForeignItem {
2596 kind: hir::ForeignItemKind::Static(_, mutbl),
2600 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2604 fn from_target_feature(
2607 attr: &ast::Attribute,
2608 whitelist: &FxHashMap<String, Option<Symbol>>,
2609 target_features: &mut Vec<Symbol>,
2611 let list = match attr.meta_item_list() {
2615 let bad_item = |span| {
2616 let msg = "malformed `target_feature` attribute input";
2617 let code = "enable = \"..\"".to_owned();
2619 .struct_span_err(span, &msg)
2620 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2623 let rust_features = tcx.features();
2625 // Only `enable = ...` is accepted in the meta-item list.
2626 if !item.check_name(sym::enable) {
2627 bad_item(item.span());
2631 // Must be of the form `enable = "..."` (a string).
2632 let value = match item.value_str() {
2633 Some(value) => value,
2635 bad_item(item.span());
2640 // We allow comma separation to enable multiple features.
2641 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2642 // Only allow whitelisted features per platform.
2643 let feature_gate = match whitelist.get(feature) {
2647 format!("the feature named `{}` is not valid for this target", feature);
2648 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2651 format!("`{}` is not valid for this target", feature),
2653 if feature.starts_with("+") {
2654 let valid = whitelist.contains_key(&feature[1..]);
2656 err.help("consider removing the leading `+` in the feature name");
2664 // Only allow features whose feature gates have been enabled.
2665 let allowed = match feature_gate.as_ref().map(|s| *s) {
2666 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2667 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2668 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2669 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2670 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2671 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2672 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2673 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2674 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2675 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2676 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2677 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2678 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2679 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2680 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2681 Some(name) => bug!("unknown target feature gate {}", name),
2684 if !allowed && id.is_local() {
2686 &tcx.sess.parse_sess,
2687 feature_gate.unwrap(),
2689 &format!("the target feature `{}` is currently unstable", feature),
2693 Some(Symbol::intern(feature))
2698 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2699 use rustc::mir::mono::Linkage::*;
2701 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2702 // applicable to variable declarations and may not really make sense for
2703 // Rust code in the first place but whitelist them anyway and trust that
2704 // the user knows what s/he's doing. Who knows, unanticipated use cases
2705 // may pop up in the future.
2707 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2708 // and don't have to be, LLVM treats them as no-ops.
2710 "appending" => Appending,
2711 "available_externally" => AvailableExternally,
2713 "extern_weak" => ExternalWeak,
2714 "external" => External,
2715 "internal" => Internal,
2716 "linkonce" => LinkOnceAny,
2717 "linkonce_odr" => LinkOnceODR,
2718 "private" => Private,
2720 "weak_odr" => WeakODR,
2722 let span = tcx.hir().span_if_local(def_id);
2723 if let Some(span) = span {
2724 tcx.sess.span_fatal(span, "invalid linkage specified")
2726 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2732 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2733 let attrs = tcx.get_attrs(id);
2735 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2737 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2739 let mut inline_span = None;
2740 let mut link_ordinal_span = None;
2741 for attr in attrs.iter() {
2742 if attr.check_name(sym::cold) {
2743 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2744 } else if attr.check_name(sym::rustc_allocator) {
2745 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2746 } else if attr.check_name(sym::unwind) {
2747 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2748 } else if attr.check_name(sym::ffi_returns_twice) {
2749 if tcx.is_foreign_item(id) {
2750 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2752 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2757 "`#[ffi_returns_twice]` may only be used on foreign functions"
2761 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2762 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2763 } else if attr.check_name(sym::naked) {
2764 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2765 } else if attr.check_name(sym::no_mangle) {
2766 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2767 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2768 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2769 } else if attr.check_name(sym::no_debug) {
2770 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2771 } else if attr.check_name(sym::used) {
2772 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2773 } else if attr.check_name(sym::thread_local) {
2774 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2775 } else if attr.check_name(sym::track_caller) {
2776 if tcx.fn_sig(id).abi() != abi::Abi::Rust {
2777 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2780 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2781 } else if attr.check_name(sym::export_name) {
2782 if let Some(s) = attr.value_str() {
2783 if s.as_str().contains("\0") {
2784 // `#[export_name = ...]` will be converted to a null-terminated string,
2785 // so it may not contain any null characters.
2790 "`export_name` may not contain null characters"
2794 codegen_fn_attrs.export_name = Some(s);
2796 } else if attr.check_name(sym::target_feature) {
2797 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2798 let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
2800 .struct_span_err(attr.span, msg)
2801 .span_label(attr.span, "can only be applied to `unsafe` functions")
2802 .span_label(tcx.def_span(id), "not an `unsafe` function")
2805 from_target_feature(tcx, id, attr, &whitelist, &mut codegen_fn_attrs.target_features);
2806 } else if attr.check_name(sym::linkage) {
2807 if let Some(val) = attr.value_str() {
2808 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2810 } else if attr.check_name(sym::link_section) {
2811 if let Some(val) = attr.value_str() {
2812 if val.as_str().bytes().any(|b| b == 0) {
2814 "illegal null byte in link_section \
2818 tcx.sess.span_err(attr.span, &msg);
2820 codegen_fn_attrs.link_section = Some(val);
2823 } else if attr.check_name(sym::link_name) {
2824 codegen_fn_attrs.link_name = attr.value_str();
2825 } else if attr.check_name(sym::link_ordinal) {
2826 link_ordinal_span = Some(attr.span);
2827 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2828 codegen_fn_attrs.link_ordinal = ordinal;
2833 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2834 if !attr.has_name(sym::inline) {
2837 match attr.meta().map(|i| i.kind) {
2838 Some(MetaItemKind::Word) => {
2842 Some(MetaItemKind::List(ref items)) => {
2844 inline_span = Some(attr.span);
2845 if items.len() != 1 {
2847 tcx.sess.diagnostic(),
2850 "expected one argument"
2854 } else if list_contains_name(&items[..], sym::always) {
2856 } else if list_contains_name(&items[..], sym::never) {
2860 tcx.sess.diagnostic(),
2870 Some(MetaItemKind::NameValue(_)) => ia,
2875 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2876 if !attr.has_name(sym::optimize) {
2879 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
2880 match attr.meta().map(|i| i.kind) {
2881 Some(MetaItemKind::Word) => {
2882 err(attr.span, "expected one argument");
2885 Some(MetaItemKind::List(ref items)) => {
2887 inline_span = Some(attr.span);
2888 if items.len() != 1 {
2889 err(attr.span, "expected one argument");
2891 } else if list_contains_name(&items[..], sym::size) {
2893 } else if list_contains_name(&items[..], sym::speed) {
2896 err(items[0].span(), "invalid argument");
2900 Some(MetaItemKind::NameValue(_)) => ia,
2905 // If a function uses #[target_feature] it can't be inlined into general
2906 // purpose functions as they wouldn't have the right target features
2907 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2910 if codegen_fn_attrs.target_features.len() > 0 {
2911 if codegen_fn_attrs.inline == InlineAttr::Always {
2912 if let Some(span) = inline_span {
2915 "cannot use `#[inline(always)]` with \
2916 `#[target_feature]`",
2922 // Weak lang items have the same semantics as "std internal" symbols in the
2923 // sense that they're preserved through all our LTO passes and only
2924 // strippable by the linker.
2926 // Additionally weak lang items have predetermined symbol names.
2927 if tcx.is_weak_lang_item(id) {
2928 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2930 if let Some(name) = weak_lang_items::link_name(&attrs) {
2931 codegen_fn_attrs.export_name = Some(name);
2932 codegen_fn_attrs.link_name = Some(name);
2934 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2936 // Internal symbols to the standard library all have no_mangle semantics in
2937 // that they have defined symbol names present in the function name. This
2938 // also applies to weak symbols where they all have known symbol names.
2939 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2940 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2946 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
2947 use syntax::ast::{Lit, LitIntType, LitKind};
2948 let meta_item_list = attr.meta_item_list();
2949 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
2950 let sole_meta_list = match meta_item_list {
2951 Some([item]) => item.literal(),
2954 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
2955 if *ordinal <= std::usize::MAX as u128 {
2956 Some(*ordinal as usize)
2958 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
2960 .struct_span_err(attr.span, &msg)
2961 .note("the value may not exceed `std::usize::MAX`")
2967 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
2968 .note("an unsuffixed integer value, e.g., `1`, is expected")
2974 fn check_link_name_xor_ordinal(
2976 codegen_fn_attrs: &CodegenFnAttrs,
2977 inline_span: Option<Span>,
2979 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
2982 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
2983 if let Some(span) = inline_span {
2984 tcx.sess.span_err(span, msg);