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_attr::{list_contains_name, mark_used, InlineAttr, OptimizeAttr};
37 use rustc_data_structures::captures::Captures;
38 use rustc_data_structures::fx::FxHashMap;
39 use rustc_errors::{struct_span_err, Applicability, StashKey};
41 use rustc_hir::def::{CtorKind, DefKind, Res};
42 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
43 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
44 use rustc_hir::{GenericParamKind, Node, Unsafety};
45 use rustc_span::symbol::{kw, sym, Symbol};
46 use rustc_span::{Span, DUMMY_SP};
47 use rustc_target::spec::abi;
49 use syntax::ast::{Ident, MetaItemKind};
51 struct OnlySelfBounds(bool);
53 ///////////////////////////////////////////////////////////////////////////
56 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: DefId) {
57 tcx.hir().visit_item_likes_in_module(
59 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
63 pub fn provide(providers: &mut Providers<'_>) {
64 *providers = Providers {
68 predicates_defined_on,
69 explicit_predicates_of,
71 type_param_predicates,
80 collect_mod_item_types,
85 ///////////////////////////////////////////////////////////////////////////
87 /// Context specific to some particular item. This is what implements
88 /// `AstConv`. It has information about the predicates that are defined
89 /// on the trait. Unfortunately, this predicate information is
90 /// available in various different forms at various points in the
91 /// process. So we can't just store a pointer to e.g., the AST or the
92 /// parsed ty form, we have to be more flexible. To this end, the
93 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
94 /// `get_type_parameter_bounds` requests, drawing the information from
95 /// the AST (`hir::Generics`), recursively.
96 pub struct ItemCtxt<'tcx> {
101 ///////////////////////////////////////////////////////////////////////////
104 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
106 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
109 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
110 NestedVisitorMap::None
112 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
113 if let hir::TyKind::Infer = t.kind {
116 intravisit::walk_ty(self, t)
120 struct CollectItemTypesVisitor<'tcx> {
124 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
125 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
126 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
127 crate fn placeholder_type_error(
130 generics: &[hir::GenericParam<'_>],
131 placeholder_types: Vec<Span>,
134 if placeholder_types.is_empty() {
137 // This is the whitelist of possible parameter names that we might suggest.
138 let possible_names = ["T", "K", "L", "A", "B", "C"];
139 let used_names = generics
141 .filter_map(|p| match p.name {
142 hir::ParamName::Plain(ident) => Some(ident.name),
145 .collect::<Vec<_>>();
147 let type_name = possible_names
149 .find(|n| !used_names.contains(&Symbol::intern(n)))
150 .unwrap_or(&"ParamName");
152 let mut sugg: Vec<_> =
153 placeholder_types.iter().map(|sp| (*sp, type_name.to_string())).collect();
154 if generics.is_empty() {
155 sugg.push((span, format!("<{}>", type_name)));
156 } else if let Some(arg) = generics.iter().find(|arg| match arg.name {
157 hir::ParamName::Plain(Ident { name: kw::Underscore, .. }) => true,
160 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
161 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
162 sugg.push((arg.span, format!("{}", type_name)));
165 generics.iter().last().unwrap().span.shrink_to_hi(),
166 format!(", {}", type_name),
169 let mut err = bad_placeholder_type(tcx, placeholder_types);
171 err.multipart_suggestion(
172 "use type parameters instead",
174 Applicability::HasPlaceholders,
180 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
181 let (generics, suggest) = match &item.kind {
182 hir::ItemKind::Union(_, generics)
183 | hir::ItemKind::Enum(_, generics)
184 | hir::ItemKind::TraitAlias(generics, _)
185 | hir::ItemKind::Trait(_, _, generics, ..)
186 | hir::ItemKind::Impl { generics, .. }
187 | hir::ItemKind::Struct(_, generics) => (generics, true),
188 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
189 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
190 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
194 let mut visitor = PlaceholderHirTyCollector::default();
195 visitor.visit_item(item);
197 placeholder_type_error(tcx, generics.span, &generics.params[..], visitor.0, suggest);
200 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
201 type Map = Map<'tcx>;
203 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
204 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
207 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
208 convert_item(self.tcx, item.hir_id);
209 reject_placeholder_type_signatures_in_item(self.tcx, item);
210 intravisit::walk_item(self, item);
213 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
214 for param in generics.params {
216 hir::GenericParamKind::Lifetime { .. } => {}
217 hir::GenericParamKind::Type { default: Some(_), .. } => {
218 let def_id = self.tcx.hir().local_def_id(param.hir_id);
219 self.tcx.type_of(def_id);
221 hir::GenericParamKind::Type { .. } => {}
222 hir::GenericParamKind::Const { .. } => {
223 let def_id = self.tcx.hir().local_def_id(param.hir_id);
224 self.tcx.type_of(def_id);
228 intravisit::walk_generics(self, generics);
231 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
232 if let hir::ExprKind::Closure(..) = expr.kind {
233 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
234 self.tcx.generics_of(def_id);
235 self.tcx.type_of(def_id);
237 intravisit::walk_expr(self, expr);
240 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
241 convert_trait_item(self.tcx, trait_item.hir_id);
242 intravisit::walk_trait_item(self, trait_item);
245 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
246 convert_impl_item(self.tcx, impl_item.hir_id);
247 intravisit::walk_impl_item(self, impl_item);
251 ///////////////////////////////////////////////////////////////////////////
252 // Utility types and common code for the above passes.
254 fn bad_placeholder_type(
256 mut spans: Vec<Span>,
257 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
259 let mut err = struct_span_err!(
263 "the type placeholder `_` is not allowed within types on item signatures",
266 err.span_label(span, "not allowed in type signatures");
271 impl ItemCtxt<'tcx> {
272 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
273 ItemCtxt { tcx, item_def_id }
276 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
277 AstConv::ast_ty_to_ty(self, ast_ty)
281 impl AstConv<'tcx> for ItemCtxt<'tcx> {
282 fn tcx(&self) -> TyCtxt<'tcx> {
286 fn item_def_id(&self) -> Option<DefId> {
287 Some(self.item_def_id)
290 fn default_constness_for_trait_bounds(&self) -> ast::Constness {
291 // FIXME: refactor this into a method
295 .as_local_hir_id(self.item_def_id)
296 .expect("Non-local call to local provider is_const_fn");
298 let node = self.tcx.hir().get(hir_id);
299 if let Some(fn_like) = FnLikeNode::from_node(node) {
302 ast::Constness::NotConst
306 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
307 self.tcx.at(span).type_param_predicates((self.item_def_id, def_id))
310 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
314 fn allow_ty_infer(&self) -> bool {
318 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
319 self.tcx().sess.delay_span_bug(span, "bad placeholder type");
326 _: Option<&ty::GenericParamDef>,
328 ) -> &'tcx Const<'tcx> {
329 bad_placeholder_type(self.tcx(), vec![span]).emit();
331 self.tcx().consts.err
334 fn projected_ty_from_poly_trait_ref(
338 item_segment: &hir::PathSegment<'_>,
339 poly_trait_ref: ty::PolyTraitRef<'tcx>,
341 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
342 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
350 self.tcx().mk_projection(item_def_id, item_substs)
352 // There are no late-bound regions; we can just ignore the binder.
357 "cannot extract an associated type from a higher-ranked trait bound \
365 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
366 // Types in item signatures are not normalized to avoid undue dependencies.
370 fn set_tainted_by_errors(&self) {
371 // There's no obvious place to track this, so just let it go.
374 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
375 // There's no place to record types from signatures?
379 /// Returns the predicates defined on `item_def_id` of the form
380 /// `X: Foo` where `X` is the type parameter `def_id`.
381 fn type_param_predicates(
383 (item_def_id, def_id): (DefId, DefId),
384 ) -> ty::GenericPredicates<'_> {
387 // In the AST, bounds can derive from two places. Either
388 // written inline like `<T: Foo>` or in a where-clause like
391 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
392 let param_owner = tcx.hir().ty_param_owner(param_id);
393 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
394 let generics = tcx.generics_of(param_owner_def_id);
395 let index = generics.param_def_id_to_index[&def_id];
396 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
398 // Don't look for bounds where the type parameter isn't in scope.
400 if item_def_id == param_owner_def_id { None } else { tcx.generics_of(item_def_id).parent };
402 let mut result = parent
404 let icx = ItemCtxt::new(tcx, parent);
405 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
407 .unwrap_or_default();
408 let mut extend = None;
410 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
411 let ast_generics = match tcx.hir().get(item_hir_id) {
412 Node::TraitItem(item) => &item.generics,
414 Node::ImplItem(item) => &item.generics,
416 Node::Item(item) => {
418 ItemKind::Fn(.., ref generics, _)
419 | ItemKind::Impl { ref generics, .. }
420 | ItemKind::TyAlias(_, ref generics)
421 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
422 | ItemKind::Enum(_, ref generics)
423 | ItemKind::Struct(_, ref generics)
424 | ItemKind::Union(_, ref generics) => generics,
425 ItemKind::Trait(_, _, ref generics, ..) => {
426 // Implied `Self: Trait` and supertrait bounds.
427 if param_id == item_hir_id {
428 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
430 Some((identity_trait_ref.without_const().to_predicate(), item.span));
438 Node::ForeignItem(item) => match item.kind {
439 ForeignItemKind::Fn(_, _, ref generics) => generics,
446 let icx = ItemCtxt::new(tcx, item_def_id);
447 let extra_predicates = extend.into_iter().chain(
448 icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
450 .filter(|(predicate, _)| match predicate {
451 ty::Predicate::Trait(ref data, _) => data.skip_binder().self_ty().is_param(index),
456 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
460 impl ItemCtxt<'tcx> {
461 /// Finds bounds from `hir::Generics`. This requires scanning through the
462 /// AST. We do this to avoid having to convert *all* the bounds, which
463 /// would create artificial cycles. Instead, we can only convert the
464 /// bounds for a type parameter `X` if `X::Foo` is used.
465 fn type_parameter_bounds_in_generics(
467 ast_generics: &'tcx hir::Generics<'tcx>,
468 param_id: hir::HirId,
470 only_self_bounds: OnlySelfBounds,
471 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
472 let constness = self.default_constness_for_trait_bounds();
473 let from_ty_params = ast_generics
476 .filter_map(|param| match param.kind {
477 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
480 .flat_map(|bounds| bounds.iter())
481 .flat_map(|b| predicates_from_bound(self, ty, b, constness));
483 let from_where_clauses = ast_generics
487 .filter_map(|wp| match *wp {
488 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
492 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
494 } else if !only_self_bounds.0 {
495 Some(self.to_ty(&bp.bounded_ty))
499 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
501 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b, constness));
503 from_ty_params.chain(from_where_clauses).collect()
507 /// Tests whether this is the AST for a reference to the type
508 /// parameter with ID `param_id`. We use this so as to avoid running
509 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
510 /// conversion of the type to avoid inducing unnecessary cycles.
511 fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
512 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
514 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
515 def_id == tcx.hir().local_def_id(param_id)
524 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::HirId) {
525 let it = tcx.hir().expect_item(item_id);
526 debug!("convert: item {} with id {}", it.ident, it.hir_id);
527 let def_id = tcx.hir().local_def_id(item_id);
529 // These don't define types.
530 hir::ItemKind::ExternCrate(_)
531 | hir::ItemKind::Use(..)
532 | hir::ItemKind::Mod(_)
533 | hir::ItemKind::GlobalAsm(_) => {}
534 hir::ItemKind::ForeignMod(ref foreign_mod) => {
535 for item in foreign_mod.items {
536 let def_id = tcx.hir().local_def_id(item.hir_id);
537 tcx.generics_of(def_id);
539 tcx.predicates_of(def_id);
540 if let hir::ForeignItemKind::Fn(..) = item.kind {
545 hir::ItemKind::Enum(ref enum_definition, _) => {
546 tcx.generics_of(def_id);
548 tcx.predicates_of(def_id);
549 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
551 hir::ItemKind::Impl { .. } => {
552 tcx.generics_of(def_id);
554 tcx.impl_trait_ref(def_id);
555 tcx.predicates_of(def_id);
557 hir::ItemKind::Trait(..) => {
558 tcx.generics_of(def_id);
559 tcx.trait_def(def_id);
560 tcx.at(it.span).super_predicates_of(def_id);
561 tcx.predicates_of(def_id);
563 hir::ItemKind::TraitAlias(..) => {
564 tcx.generics_of(def_id);
565 tcx.at(it.span).super_predicates_of(def_id);
566 tcx.predicates_of(def_id);
568 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
569 tcx.generics_of(def_id);
571 tcx.predicates_of(def_id);
573 for f in struct_def.fields() {
574 let def_id = tcx.hir().local_def_id(f.hir_id);
575 tcx.generics_of(def_id);
577 tcx.predicates_of(def_id);
580 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
581 convert_variant_ctor(tcx, ctor_hir_id);
585 // Desugared from `impl Trait`, so visited by the function's return type.
586 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
588 hir::ItemKind::OpaqueTy(..)
589 | hir::ItemKind::TyAlias(..)
590 | hir::ItemKind::Static(..)
591 | hir::ItemKind::Const(..)
592 | hir::ItemKind::Fn(..) => {
593 tcx.generics_of(def_id);
595 tcx.predicates_of(def_id);
596 if let hir::ItemKind::Fn(..) = it.kind {
603 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
604 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
605 let def_id = tcx.hir().local_def_id(trait_item.hir_id);
606 tcx.generics_of(def_id);
608 match trait_item.kind {
609 hir::TraitItemKind::Const(..)
610 | hir::TraitItemKind::Type(_, Some(_))
611 | hir::TraitItemKind::Method(..) => {
613 if let hir::TraitItemKind::Method(..) = trait_item.kind {
618 hir::TraitItemKind::Type(_, None) => {}
621 tcx.predicates_of(def_id);
624 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
625 let def_id = tcx.hir().local_def_id(impl_item_id);
626 tcx.generics_of(def_id);
628 tcx.predicates_of(def_id);
629 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).kind {
634 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
635 let def_id = tcx.hir().local_def_id(ctor_id);
636 tcx.generics_of(def_id);
638 tcx.predicates_of(def_id);
641 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
642 let def = tcx.adt_def(def_id);
643 let repr_type = def.repr.discr_type();
644 let initial = repr_type.initial_discriminant(tcx);
645 let mut prev_discr = None::<Discr<'_>>;
647 // fill the discriminant values and field types
648 for variant in variants {
649 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
651 if let Some(ref e) = variant.disr_expr {
652 let expr_did = tcx.hir().local_def_id(e.hir_id);
653 def.eval_explicit_discr(tcx, expr_did)
654 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
657 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
660 format!("overflowed on value after {}", prev_discr.unwrap()),
663 "explicitly set `{} = {}` if that is desired outcome",
664 variant.ident, wrapped_discr
669 .unwrap_or(wrapped_discr),
672 for f in variant.data.fields() {
673 let def_id = tcx.hir().local_def_id(f.hir_id);
674 tcx.generics_of(def_id);
676 tcx.predicates_of(def_id);
679 // Convert the ctor, if any. This also registers the variant as
681 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
682 convert_variant_ctor(tcx, ctor_hir_id);
689 variant_did: Option<DefId>,
690 ctor_did: Option<DefId>,
692 discr: ty::VariantDiscr,
693 def: &hir::VariantData<'_>,
694 adt_kind: ty::AdtKind,
696 ) -> ty::VariantDef {
697 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
698 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
703 let fid = tcx.hir().local_def_id(f.hir_id);
704 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
705 if let Some(prev_span) = dup_span {
710 "field `{}` is already declared",
713 .span_label(f.span, "field already declared")
714 .span_label(prev_span, format!("`{}` first declared here", f.ident))
717 seen_fields.insert(f.ident.modern(), f.span);
723 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
727 let recovered = match def {
728 hir::VariantData::Struct(_, r) => *r,
738 CtorKind::from_hir(def),
745 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
748 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
749 let item = match tcx.hir().get(hir_id) {
750 Node::Item(item) => item,
754 let repr = ReprOptions::new(tcx, def_id);
755 let (kind, variants) = match item.kind {
756 ItemKind::Enum(ref def, _) => {
757 let mut distance_from_explicit = 0;
762 let variant_did = Some(tcx.hir().local_def_id(v.id));
764 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
766 let discr = if let Some(ref e) = v.disr_expr {
767 distance_from_explicit = 0;
768 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id))
770 ty::VariantDiscr::Relative(distance_from_explicit)
772 distance_from_explicit += 1;
787 (AdtKind::Enum, variants)
789 ItemKind::Struct(ref def, _) => {
790 let variant_did = None;
791 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
793 let variants = std::iter::once(convert_variant(
798 ty::VariantDiscr::Relative(0),
805 (AdtKind::Struct, variants)
807 ItemKind::Union(ref def, _) => {
808 let variant_did = None;
809 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
811 let variants = std::iter::once(convert_variant(
816 ty::VariantDiscr::Relative(0),
823 (AdtKind::Union, variants)
827 tcx.alloc_adt_def(def_id, kind, variants, repr)
830 /// Ensures that the super-predicates of the trait with a `DefId`
831 /// of `trait_def_id` are converted and stored. This also ensures that
832 /// the transitive super-predicates are converted.
833 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
834 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
835 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
837 let item = match tcx.hir().get(trait_hir_id) {
838 Node::Item(item) => item,
839 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
842 let (generics, bounds) = match item.kind {
843 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
844 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
845 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
848 let icx = ItemCtxt::new(tcx, trait_def_id);
850 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
851 let self_param_ty = tcx.types.self_param;
853 AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
855 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
857 // Convert any explicit superbounds in the where-clause,
858 // e.g., `trait Foo where Self: Bar`.
859 // In the case of trait aliases, however, we include all bounds in the where-clause,
860 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
861 // as one of its "superpredicates".
862 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
863 let superbounds2 = icx.type_parameter_bounds_in_generics(
867 OnlySelfBounds(!is_trait_alias),
870 // Combine the two lists to form the complete set of superbounds:
871 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
873 // Now require that immediate supertraits are converted,
874 // which will, in turn, reach indirect supertraits.
875 for &(pred, span) in superbounds {
876 debug!("superbound: {:?}", pred);
877 if let ty::Predicate::Trait(bound, _) = pred {
878 tcx.at(span).super_predicates_of(bound.def_id());
882 ty::GenericPredicates { parent: None, predicates: superbounds }
885 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
886 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
887 let item = tcx.hir().expect_item(hir_id);
889 let (is_auto, unsafety) = match item.kind {
890 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
891 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
892 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
895 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
896 if paren_sugar && !tcx.features().unboxed_closures {
900 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
901 which traits can use parenthetical notation",
903 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
907 let is_marker = tcx.has_attr(def_id, sym::marker);
908 let def_path_hash = tcx.def_path_hash(def_id);
909 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
913 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
914 struct LateBoundRegionsDetector<'tcx> {
916 outer_index: ty::DebruijnIndex,
917 has_late_bound_regions: Option<Span>,
920 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
921 type Map = Map<'tcx>;
923 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
924 NestedVisitorMap::None
927 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
928 if self.has_late_bound_regions.is_some() {
932 hir::TyKind::BareFn(..) => {
933 self.outer_index.shift_in(1);
934 intravisit::walk_ty(self, ty);
935 self.outer_index.shift_out(1);
937 _ => intravisit::walk_ty(self, ty),
941 fn visit_poly_trait_ref(
943 tr: &'tcx hir::PolyTraitRef<'tcx>,
944 m: hir::TraitBoundModifier,
946 if self.has_late_bound_regions.is_some() {
949 self.outer_index.shift_in(1);
950 intravisit::walk_poly_trait_ref(self, tr, m);
951 self.outer_index.shift_out(1);
954 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
955 if self.has_late_bound_regions.is_some() {
959 match self.tcx.named_region(lt.hir_id) {
960 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
961 Some(rl::Region::LateBound(debruijn, _, _))
962 | Some(rl::Region::LateBoundAnon(debruijn, _))
963 if debruijn < self.outer_index => {}
964 Some(rl::Region::LateBound(..))
965 | Some(rl::Region::LateBoundAnon(..))
966 | Some(rl::Region::Free(..))
968 self.has_late_bound_regions = Some(lt.span);
974 fn has_late_bound_regions<'tcx>(
976 generics: &'tcx hir::Generics<'tcx>,
977 decl: &'tcx hir::FnDecl<'tcx>,
979 let mut visitor = LateBoundRegionsDetector {
981 outer_index: ty::INNERMOST,
982 has_late_bound_regions: None,
984 for param in generics.params {
985 if let GenericParamKind::Lifetime { .. } = param.kind {
986 if tcx.is_late_bound(param.hir_id) {
987 return Some(param.span);
991 visitor.visit_fn_decl(decl);
992 visitor.has_late_bound_regions
996 Node::TraitItem(item) => match item.kind {
997 hir::TraitItemKind::Method(ref sig, _) => {
998 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1002 Node::ImplItem(item) => match item.kind {
1003 hir::ImplItemKind::Method(ref sig, _) => {
1004 has_late_bound_regions(tcx, &item.generics, &sig.decl)
1008 Node::ForeignItem(item) => match item.kind {
1009 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
1010 has_late_bound_regions(tcx, generics, fn_decl)
1014 Node::Item(item) => match item.kind {
1015 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1016 has_late_bound_regions(tcx, generics, &sig.decl)
1024 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
1027 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1029 let node = tcx.hir().get(hir_id);
1030 let parent_def_id = match node {
1032 | Node::TraitItem(_)
1035 | Node::Field(_) => {
1036 let parent_id = tcx.hir().get_parent_item(hir_id);
1037 Some(tcx.hir().local_def_id(parent_id))
1039 // FIXME(#43408) enable this always when we get lazy normalization.
1040 Node::AnonConst(_) => {
1041 // HACK(eddyb) this provides the correct generics when
1042 // `feature(const_generics)` is enabled, so that const expressions
1043 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1044 if tcx.features().const_generics {
1045 let parent_id = tcx.hir().get_parent_item(hir_id);
1046 Some(tcx.hir().local_def_id(parent_id))
1051 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1052 Some(tcx.closure_base_def_id(def_id))
1054 Node::Item(item) => match item.kind {
1055 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => impl_trait_fn,
1061 let mut opt_self = None;
1062 let mut allow_defaults = false;
1064 let no_generics = hir::Generics::empty();
1065 let ast_generics = match node {
1066 Node::TraitItem(item) => &item.generics,
1068 Node::ImplItem(item) => &item.generics,
1070 Node::Item(item) => {
1072 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl { ref generics, .. } => generics,
1074 ItemKind::TyAlias(_, ref generics)
1075 | ItemKind::Enum(_, ref generics)
1076 | ItemKind::Struct(_, ref generics)
1077 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1078 | ItemKind::Union(_, ref generics) => {
1079 allow_defaults = true;
1083 ItemKind::Trait(_, _, ref generics, ..)
1084 | ItemKind::TraitAlias(ref generics, ..) => {
1085 // Add in the self type parameter.
1087 // Something of a hack: use the node id for the trait, also as
1088 // the node id for the Self type parameter.
1089 let param_id = item.hir_id;
1091 opt_self = Some(ty::GenericParamDef {
1093 name: kw::SelfUpper,
1094 def_id: tcx.hir().local_def_id(param_id),
1095 pure_wrt_drop: false,
1096 kind: ty::GenericParamDefKind::Type {
1098 object_lifetime_default: rl::Set1::Empty,
1103 allow_defaults = true;
1111 Node::ForeignItem(item) => match item.kind {
1112 ForeignItemKind::Static(..) => &no_generics,
1113 ForeignItemKind::Fn(_, _, ref generics) => generics,
1114 ForeignItemKind::Type => &no_generics,
1120 let has_self = opt_self.is_some();
1121 let mut parent_has_self = false;
1122 let mut own_start = has_self as u32;
1123 let parent_count = parent_def_id.map_or(0, |def_id| {
1124 let generics = tcx.generics_of(def_id);
1125 assert_eq!(has_self, false);
1126 parent_has_self = generics.has_self;
1127 own_start = generics.count() as u32;
1128 generics.parent_count + generics.params.len()
1131 let mut params: Vec<_> = opt_self.into_iter().collect();
1133 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1134 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1135 name: param.name.ident().name,
1136 index: own_start + i as u32,
1137 def_id: tcx.hir().local_def_id(param.hir_id),
1138 pure_wrt_drop: param.pure_wrt_drop,
1139 kind: ty::GenericParamDefKind::Lifetime,
1142 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1144 // Now create the real type parameters.
1145 let type_start = own_start - has_self as u32 + params.len() as u32;
1147 params.extend(ast_generics.params.iter().filter_map(|param| {
1148 let kind = match param.kind {
1149 GenericParamKind::Type { ref default, synthetic, .. } => {
1150 if !allow_defaults && default.is_some() {
1151 if !tcx.features().default_type_parameter_fallback {
1153 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1157 "defaults for type parameters are only allowed in \
1158 `struct`, `enum`, `type`, or `trait` definitions."
1164 ty::GenericParamDefKind::Type {
1165 has_default: default.is_some(),
1166 object_lifetime_default: object_lifetime_defaults
1168 .map_or(rl::Set1::Empty, |o| o[i]),
1172 GenericParamKind::Const { .. } => ty::GenericParamDefKind::Const,
1176 let param_def = ty::GenericParamDef {
1177 index: type_start + i as u32,
1178 name: param.name.ident().name,
1179 def_id: tcx.hir().local_def_id(param.hir_id),
1180 pure_wrt_drop: param.pure_wrt_drop,
1187 // provide junk type parameter defs - the only place that
1188 // cares about anything but the length is instantiation,
1189 // and we don't do that for closures.
1190 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1191 let dummy_args = if gen.is_some() {
1192 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1194 &["<closure_kind>", "<closure_signature>"][..]
1197 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1198 index: type_start + i as u32,
1199 name: Symbol::intern(arg),
1201 pure_wrt_drop: false,
1202 kind: ty::GenericParamDefKind::Type {
1204 object_lifetime_default: rl::Set1::Empty,
1209 if let Some(upvars) = tcx.upvars(def_id) {
1210 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1211 ty::GenericParamDef {
1212 index: type_start + i,
1213 name: Symbol::intern("<upvar>"),
1215 pure_wrt_drop: false,
1216 kind: ty::GenericParamDefKind::Type {
1218 object_lifetime_default: rl::Set1::Empty,
1226 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1228 tcx.arena.alloc(ty::Generics {
1229 parent: parent_def_id,
1232 param_def_id_to_index,
1233 has_self: has_self || parent_has_self,
1234 has_late_bound_regions: has_late_bound_regions(tcx, node),
1238 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
1243 "associated types are not yet supported in inherent impls (see #8995)"
1248 fn infer_placeholder_type(
1251 body_id: hir::BodyId,
1255 let ty = tcx.diagnostic_only_typeck_tables_of(def_id).node_type(body_id.hir_id);
1257 // If this came from a free `const` or `static mut?` item,
1258 // then the user may have written e.g. `const A = 42;`.
1259 // In this case, the parser has stashed a diagnostic for
1260 // us to improve in typeck so we do that now.
1261 match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
1263 // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
1264 // We are typeck and have the real type, so remove that and suggest the actual type.
1265 err.suggestions.clear();
1266 err.span_suggestion(
1268 "provide a type for the item",
1269 format!("{}: {}", item_ident, ty),
1270 Applicability::MachineApplicable,
1275 let mut diag = bad_placeholder_type(tcx, vec![span]);
1276 if ty != tcx.types.err {
1277 diag.span_suggestion(
1279 "replace `_` with the correct type",
1281 Applicability::MaybeIncorrect,
1291 fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1294 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1296 let icx = ItemCtxt::new(tcx, def_id);
1298 match tcx.hir().get(hir_id) {
1299 Node::TraitItem(item) => match item.kind {
1300 TraitItemKind::Method(..) => {
1301 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1302 tcx.mk_fn_def(def_id, substs)
1304 TraitItemKind::Const(ref ty, body_id) => body_id
1305 .and_then(|body_id| {
1306 if is_suggestable_infer_ty(ty) {
1307 Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
1312 .unwrap_or_else(|| icx.to_ty(ty)),
1313 TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1314 TraitItemKind::Type(_, None) => {
1315 span_bug!(item.span, "associated type missing default");
1319 Node::ImplItem(item) => match item.kind {
1320 ImplItemKind::Method(..) => {
1321 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1322 tcx.mk_fn_def(def_id, substs)
1324 ImplItemKind::Const(ref ty, body_id) => {
1325 if is_suggestable_infer_ty(ty) {
1326 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1331 ImplItemKind::OpaqueTy(_) => {
1332 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1333 report_assoc_ty_on_inherent_impl(tcx, item.span);
1336 find_opaque_ty_constraints(tcx, def_id)
1338 ImplItemKind::TyAlias(ref ty) => {
1339 if tcx.impl_trait_ref(tcx.hir().get_parent_did(hir_id)).is_none() {
1340 report_assoc_ty_on_inherent_impl(tcx, item.span);
1347 Node::Item(item) => {
1349 ItemKind::Static(ref ty, .., body_id) | ItemKind::Const(ref ty, body_id) => {
1350 if is_suggestable_infer_ty(ty) {
1351 infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
1356 ItemKind::TyAlias(ref self_ty, _) | ItemKind::Impl { ref self_ty, .. } => {
1359 ItemKind::Fn(..) => {
1360 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1361 tcx.mk_fn_def(def_id, substs)
1363 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1364 let def = tcx.adt_def(def_id);
1365 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1366 tcx.mk_adt(def, substs)
1368 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: None, .. }) => {
1369 find_opaque_ty_constraints(tcx, def_id)
1371 // Opaque types desugared from `impl Trait`.
1372 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(owner), .. }) => {
1373 tcx.typeck_tables_of(owner)
1374 .concrete_opaque_types
1376 .map(|opaque| opaque.concrete_type)
1377 .unwrap_or_else(|| {
1378 // This can occur if some error in the
1379 // owner fn prevented us from populating
1380 // the `concrete_opaque_types` table.
1381 tcx.sess.delay_span_bug(
1384 "owner {:?} has no opaque type for {:?} in its tables",
1392 | ItemKind::TraitAlias(..)
1394 | ItemKind::ForeignMod(..)
1395 | ItemKind::GlobalAsm(..)
1396 | ItemKind::ExternCrate(..)
1397 | ItemKind::Use(..) => {
1400 "compute_type_of_item: unexpected item type: {:?}",
1407 Node::ForeignItem(foreign_item) => match foreign_item.kind {
1408 ForeignItemKind::Fn(..) => {
1409 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1410 tcx.mk_fn_def(def_id, substs)
1412 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1413 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1416 Node::Ctor(&ref def) | Node::Variant(hir::Variant { data: ref def, .. }) => match *def {
1417 VariantData::Unit(..) | VariantData::Struct(..) => {
1418 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1420 VariantData::Tuple(..) => {
1421 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1422 tcx.mk_fn_def(def_id, substs)
1426 Node::Field(field) => icx.to_ty(&field.ty),
1428 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) => {
1430 return tcx.typeck_tables_of(def_id).node_type(hir_id);
1433 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1434 tcx.mk_closure(def_id, substs)
1437 Node::AnonConst(_) => {
1438 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1440 Node::Ty(&hir::Ty { kind: hir::TyKind::Array(_, ref constant), .. })
1441 | Node::Ty(&hir::Ty { kind: hir::TyKind::Typeof(ref constant), .. })
1442 | Node::Expr(&hir::Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1443 if constant.hir_id == hir_id =>
1448 Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => {
1449 tcx.adt_def(tcx.hir().get_parent_did(hir_id)).repr.discr_type().to_ty(tcx)
1452 Node::Ty(&hir::Ty { kind: hir::TyKind::Path(_), .. })
1453 | Node::Expr(&hir::Expr { kind: ExprKind::Struct(..), .. })
1454 | Node::Expr(&hir::Expr { kind: ExprKind::Path(_), .. })
1455 | Node::TraitRef(..) => {
1456 let path = match parent_node {
1458 kind: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1461 | Node::Expr(&hir::Expr {
1462 kind: ExprKind::Path(QPath::Resolved(_, ref path)),
1464 }) => Some(&**path),
1465 Node::Expr(&hir::Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
1466 if let QPath::Resolved(_, ref path) = **path {
1472 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
1476 if let Some(path) = path {
1477 let arg_index = path
1480 .filter_map(|seg| seg.args.as_ref())
1481 .map(|generic_args| generic_args.args.as_ref())
1484 .filter(|arg| arg.is_const())
1486 .filter(|(_, arg)| arg.id() == hir_id)
1487 .map(|(index, _)| index)
1490 .unwrap_or_else(|| {
1491 bug!("no arg matching AnonConst in path");
1494 // We've encountered an `AnonConst` in some path, so we need to
1495 // figure out which generic parameter it corresponds to and return
1496 // the relevant type.
1497 let generics = match path.res {
1498 Res::Def(DefKind::Ctor(..), def_id) => {
1499 tcx.generics_of(tcx.parent(def_id).unwrap())
1501 Res::Def(_, def_id) => tcx.generics_of(def_id),
1502 Res::Err => return tcx.types.err,
1504 tcx.sess.delay_span_bug(
1506 &format!("unexpected const parent path def {:?}", res,),
1508 return tcx.types.err;
1516 if let ty::GenericParamDefKind::Const = param.kind {
1523 .map(|param| tcx.type_of(param.def_id))
1524 // This is no generic parameter associated with the arg. This is
1525 // probably from an extra arg where one is not needed.
1526 .unwrap_or(tcx.types.err)
1528 tcx.sess.delay_span_bug(
1530 &format!("unexpected const parent path {:?}", parent_node,),
1532 return tcx.types.err;
1537 tcx.sess.delay_span_bug(
1539 &format!("unexpected const parent in type_of_def_id(): {:?}", x),
1546 Node::GenericParam(param) => match ¶m.kind {
1547 hir::GenericParamKind::Type { default: Some(ref ty), .. } => icx.to_ty(ty),
1548 hir::GenericParamKind::Const { ty: ref hir_ty, .. } => {
1549 let ty = icx.to_ty(hir_ty);
1550 if !tcx.features().const_compare_raw_pointers {
1551 let err = match ty.peel_refs().kind {
1552 ty::FnPtr(_) => Some("function pointers"),
1553 ty::RawPtr(_) => Some("raw pointers"),
1556 if let Some(unsupported_type) = err {
1558 &tcx.sess.parse_sess,
1559 sym::const_compare_raw_pointers,
1562 "using {} as const generic parameters is unstable",
1569 if traits::search_for_structural_match_violation(param.hir_id, param.span, tcx, ty)
1576 "the types of const generic parameters must derive `PartialEq` and `Eq`",
1580 format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
1586 x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
1590 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1595 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
1596 use rustc_hir::{ImplItem, Item, TraitItem};
1598 debug!("find_opaque_ty_constraints({:?})", def_id);
1600 struct ConstraintLocator<'tcx> {
1603 // (first found type span, actual type, mapping from the opaque type's generic
1604 // parameters to the concrete type's generic parameters)
1606 // The mapping is an index for each use site of a generic parameter in the concrete type
1608 // The indices index into the generic parameters on the opaque type.
1609 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1612 impl ConstraintLocator<'tcx> {
1613 fn check(&mut self, def_id: DefId) {
1614 // Don't try to check items that cannot possibly constrain the type.
1615 if !self.tcx.has_typeck_tables(def_id) {
1617 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1618 self.def_id, def_id,
1622 let ty = self.tcx.typeck_tables_of(def_id).concrete_opaque_types.get(&self.def_id);
1623 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1625 "find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1626 self.def_id, def_id, ty,
1629 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1630 let span = self.tcx.def_span(def_id);
1631 // used to quickly look up the position of a generic parameter
1632 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1633 // Skipping binder is ok, since we only use this to find generic parameters and
1635 for (idx, subst) in substs.iter().enumerate() {
1636 if let GenericArgKind::Type(ty) = subst.unpack() {
1637 if let ty::Param(p) = ty.kind {
1638 if index_map.insert(p, idx).is_some() {
1639 // There was already an entry for `p`, meaning a generic parameter
1641 self.tcx.sess.span_err(
1644 "defining opaque type use restricts opaque \
1645 type by using the generic parameter `{}` twice",
1652 self.tcx.sess.delay_span_bug(
1655 "non-defining opaque ty use in defining scope: {:?}, {:?}",
1656 concrete_type, substs,
1662 // Compute the index within the opaque type for each generic parameter used in
1663 // the concrete type.
1664 let indices = concrete_type
1665 .subst(self.tcx, substs)
1667 .filter_map(|t| match &t.kind {
1668 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1672 let is_param = |ty: Ty<'_>| match ty.kind {
1673 ty::Param(_) => true,
1676 let bad_substs: Vec<_> = substs
1679 .filter_map(|(i, k)| {
1680 if let GenericArgKind::Type(ty) = k.unpack() { Some((i, ty)) } else { None }
1682 .filter(|(_, ty)| !is_param(ty))
1685 if !bad_substs.is_empty() {
1686 let identity_substs = InternalSubsts::identity_for_item(self.tcx, self.def_id);
1687 for (i, bad_subst) in bad_substs {
1688 self.tcx.sess.span_err(
1691 "defining opaque type use does not fully define opaque type: \
1692 generic parameter `{}` is specified as concrete type `{}`",
1693 identity_substs.type_at(i),
1698 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1699 let mut ty = concrete_type.walk().fuse();
1700 let mut p_ty = prev_ty.walk().fuse();
1701 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.kind, &p.kind) {
1702 // Type parameters are equal to any other type parameter for the purpose of
1703 // concrete type equality, as it is possible to obtain the same type just
1704 // by passing matching parameters to a function.
1705 (ty::Param(_), ty::Param(_)) => true,
1708 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1709 debug!("find_opaque_ty_constraints: span={:?}", span);
1710 // Found different concrete types for the opaque type.
1711 let mut err = self.tcx.sess.struct_span_err(
1713 "concrete type differs from previous defining opaque type use",
1717 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1719 err.span_note(prev_span, "previous use here");
1721 } else if indices != *prev_indices {
1722 // Found "same" concrete types, but the generic parameter order differs.
1723 let mut err = self.tcx.sess.struct_span_err(
1725 "concrete type's generic parameters differ from previous defining use",
1727 use std::fmt::Write;
1728 let mut s = String::new();
1729 write!(s, "expected [").unwrap();
1730 let list = |s: &mut String, indices: &Vec<usize>| {
1731 let mut indices = indices.iter().cloned();
1732 if let Some(first) = indices.next() {
1733 write!(s, "`{}`", substs[first]).unwrap();
1735 write!(s, ", `{}`", substs[i]).unwrap();
1739 list(&mut s, prev_indices);
1740 write!(s, "], got [").unwrap();
1741 list(&mut s, &indices);
1742 write!(s, "]").unwrap();
1743 err.span_label(span, s);
1744 err.span_note(prev_span, "previous use here");
1748 self.found = Some((span, concrete_type, indices));
1752 "find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
1753 self.def_id, def_id,
1759 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1760 type Map = Map<'tcx>;
1762 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<'_, Self::Map> {
1763 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1765 fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
1766 debug!("find_existential_constraints: visiting {:?}", it);
1767 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1768 // The opaque type itself or its children are not within its reveal scope.
1769 if def_id != self.def_id {
1771 intravisit::walk_item(self, it);
1774 fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
1775 debug!("find_existential_constraints: visiting {:?}", it);
1776 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1777 // The opaque type itself or its children are not within its reveal scope.
1778 if def_id != self.def_id {
1780 intravisit::walk_impl_item(self, it);
1783 fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
1784 debug!("find_existential_constraints: visiting {:?}", it);
1785 let def_id = self.tcx.hir().local_def_id(it.hir_id);
1787 intravisit::walk_trait_item(self, it);
1791 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1792 let scope = tcx.hir().get_defining_scope(hir_id);
1793 let mut locator = ConstraintLocator { def_id, tcx, found: None };
1795 debug!("find_opaque_ty_constraints: scope={:?}", scope);
1797 if scope == hir::CRATE_HIR_ID {
1798 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1800 debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
1801 match tcx.hir().get(scope) {
1802 // We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
1803 // This allows our visitor to process the defining item itself, causing
1804 // it to pick up any 'sibling' defining uses.
1806 // For example, this code:
1809 // type Blah = impl Debug;
1810 // let my_closure = || -> Blah { true };
1814 // requires us to explicitly process `foo()` in order
1815 // to notice the defining usage of `Blah`.
1816 Node::Item(ref it) => locator.visit_item(it),
1817 Node::ImplItem(ref it) => locator.visit_impl_item(it),
1818 Node::TraitItem(ref it) => locator.visit_trait_item(it),
1819 other => bug!("{:?} is not a valid scope for an opaque type item", other),
1823 match locator.found {
1824 Some((_, ty, _)) => ty,
1826 let span = tcx.def_span(def_id);
1827 tcx.sess.span_err(span, "could not find defining uses");
1833 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1836 .filter_map(|arg| match arg {
1837 hir::GenericArg::Type(ty) => Some(ty),
1840 .any(is_suggestable_infer_ty)
1843 /// Whether `ty` is a type with `_` placeholders that can be infered. Used in diagnostics only to
1844 /// use inference to provide suggestions for the appropriate type if possible.
1845 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1849 Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
1850 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1851 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1852 Def(_, generic_args) => are_suggestable_generic_args(generic_args),
1853 Path(hir::QPath::TypeRelative(ty, segment)) => {
1854 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.generic_args().args)
1856 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1857 ty_opt.map_or(false, is_suggestable_infer_ty)
1860 .any(|segment| are_suggestable_generic_args(segment.generic_args().args))
1866 pub fn get_infer_ret_ty(output: &'hir hir::FunctionRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1867 if let hir::FunctionRetTy::Return(ref ty) = output {
1868 if is_suggestable_infer_ty(ty) {
1875 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1876 use rustc_hir::Node::*;
1879 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1881 let icx = ItemCtxt::new(tcx, def_id);
1883 match tcx.hir().get(hir_id) {
1884 TraitItem(hir::TraitItem {
1885 kind: TraitItemKind::Method(sig, TraitMethod::Provided(_)),
1890 | ImplItem(hir::ImplItem { kind: ImplItemKind::Method(sig, _), ident, generics, .. })
1891 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1892 match get_infer_ret_ty(&sig.decl.output) {
1894 let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
1895 let mut visitor = PlaceholderHirTyCollector::default();
1896 visitor.visit_ty(ty);
1897 let mut diag = bad_placeholder_type(tcx, visitor.0);
1898 let ret_ty = fn_sig.output();
1899 if ret_ty != tcx.types.err {
1900 diag.span_suggestion(
1902 "replace with the correct return type",
1904 Applicability::MaybeIncorrect,
1908 ty::Binder::bind(fn_sig)
1910 None => AstConv::ty_of_fn(
1912 sig.header.unsafety,
1915 &generics.params[..],
1921 TraitItem(hir::TraitItem {
1922 kind: TraitItemKind::Method(FnSig { header, decl }, _),
1926 }) => AstConv::ty_of_fn(
1931 &generics.params[..],
1935 ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(ref fn_decl, _, _), .. }) => {
1936 let abi = tcx.hir().get_foreign_abi(hir_id);
1937 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1940 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1941 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1943 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1944 ty::Binder::bind(tcx.mk_fn_sig(
1948 hir::Unsafety::Normal,
1953 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1954 // Closure signatures are not like other function
1955 // signatures and cannot be accessed through `fn_sig`. For
1956 // example, a closure signature excludes the `self`
1957 // argument. In any case they are embedded within the
1958 // closure type as part of the `ClosureSubsts`.
1961 // the signature of a closure, you should use the
1962 // `closure_sig` method on the `ClosureSubsts`:
1964 // closure_substs.sig(def_id, tcx)
1966 // or, inside of an inference context, you can use
1968 // infcx.closure_sig(def_id, closure_substs)
1969 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1973 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1978 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1979 let icx = ItemCtxt::new(tcx, def_id);
1981 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1982 match tcx.hir().expect_item(hir_id).kind {
1983 hir::ItemKind::Impl { ref of_trait, .. } => of_trait.as_ref().map(|ast_trait_ref| {
1984 let selfty = tcx.type_of(def_id);
1985 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1991 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1992 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1993 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1994 let item = tcx.hir().expect_item(hir_id);
1996 hir::ItemKind::Impl { polarity: hir::ImplPolarity::Negative, .. } => {
1997 if is_rustc_reservation {
1998 tcx.sess.span_err(item.span, "reservation impls can't be negative");
2000 ty::ImplPolarity::Negative
2002 hir::ItemKind::Impl { polarity: hir::ImplPolarity::Positive, of_trait: None, .. } => {
2003 if is_rustc_reservation {
2004 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
2006 ty::ImplPolarity::Positive
2008 hir::ItemKind::Impl {
2009 polarity: hir::ImplPolarity::Positive, of_trait: Some(_), ..
2011 if is_rustc_reservation {
2012 ty::ImplPolarity::Reservation
2014 ty::ImplPolarity::Positive
2017 ref item => bug!("impl_polarity: {:?} not an impl", item),
2021 /// Returns the early-bound lifetimes declared in this generics
2022 /// listing. For anything other than fns/methods, this is just all
2023 /// the lifetimes that are declared. For fns or methods, we have to
2024 /// screen out those that do not appear in any where-clauses etc using
2025 /// `resolve_lifetime::early_bound_lifetimes`.
2026 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
2028 generics: &'a hir::Generics<'a>,
2029 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
2030 generics.params.iter().filter(move |param| match param.kind {
2031 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
2036 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
2037 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
2038 /// inferred constraints concerning which regions outlive other regions.
2039 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2040 debug!("predicates_defined_on({:?})", def_id);
2041 let mut result = tcx.explicit_predicates_of(def_id);
2042 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
2043 let inferred_outlives = tcx.inferred_outlives_of(def_id);
2044 if !inferred_outlives.is_empty() {
2046 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
2047 def_id, inferred_outlives,
2049 if result.predicates.is_empty() {
2050 result.predicates = inferred_outlives;
2052 result.predicates = tcx
2054 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
2057 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
2061 /// Returns a list of all type predicates (explicit and implicit) for the definition with
2062 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
2063 /// `Self: Trait` predicates for traits.
2064 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2065 let mut result = tcx.predicates_defined_on(def_id);
2067 if tcx.is_trait(def_id) {
2068 // For traits, add `Self: Trait` predicate. This is
2069 // not part of the predicates that a user writes, but it
2070 // is something that one must prove in order to invoke a
2071 // method or project an associated type.
2073 // In the chalk setup, this predicate is not part of the
2074 // "predicates" for a trait item. But it is useful in
2075 // rustc because if you directly (e.g.) invoke a trait
2076 // method like `Trait::method(...)`, you must naturally
2077 // prove that the trait applies to the types that were
2078 // used, and adding the predicate into this list ensures
2079 // that this is done.
2080 let span = tcx.def_span(def_id);
2082 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2083 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(),
2087 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2091 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2092 /// N.B., this does not include any implied/inferred constraints.
2093 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2094 use rustc_data_structures::fx::FxHashSet;
2097 debug!("explicit_predicates_of(def_id={:?})", def_id);
2099 /// A data structure with unique elements, which preserves order of insertion.
2100 /// Preserving the order of insertion is important here so as not to break
2101 /// compile-fail UI tests.
2102 // FIXME(eddyb) just use `IndexSet` from `indexmap`.
2103 struct UniquePredicates<'tcx> {
2104 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
2105 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
2108 impl<'tcx> UniquePredicates<'tcx> {
2110 UniquePredicates { predicates: vec![], uniques: FxHashSet::default() }
2113 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
2114 if self.uniques.insert(value) {
2115 self.predicates.push(value);
2119 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
2126 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
2127 let node = tcx.hir().get(hir_id);
2129 let mut is_trait = None;
2130 let mut is_default_impl_trait = None;
2132 let icx = ItemCtxt::new(tcx, def_id);
2133 let constness = icx.default_constness_for_trait_bounds();
2135 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2137 let mut predicates = UniquePredicates::new();
2139 let ast_generics = match node {
2140 Node::TraitItem(item) => &item.generics,
2142 Node::ImplItem(item) => match item.kind {
2143 ImplItemKind::OpaqueTy(ref bounds) => {
2144 ty::print::with_no_queries(|| {
2145 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2146 let opaque_ty = tcx.mk_opaque(def_id, substs);
2148 "explicit_predicates_of({:?}): created opaque type {:?}",
2152 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2153 let bounds = AstConv::compute_bounds(
2157 SizedByDefault::Yes,
2158 tcx.def_span(def_id),
2161 predicates.extend(bounds.predicates(tcx, opaque_ty));
2165 _ => &item.generics,
2168 Node::Item(item) => {
2170 ItemKind::Impl { defaultness, ref generics, .. } => {
2171 if defaultness.is_default() {
2172 is_default_impl_trait = tcx.impl_trait_ref(def_id);
2176 ItemKind::Fn(.., ref generics, _)
2177 | ItemKind::TyAlias(_, ref generics)
2178 | ItemKind::Enum(_, ref generics)
2179 | ItemKind::Struct(_, ref generics)
2180 | ItemKind::Union(_, ref generics) => generics,
2182 ItemKind::Trait(_, _, ref generics, .., items) => {
2183 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
2186 ItemKind::TraitAlias(ref generics, _) => {
2187 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &[]));
2190 ItemKind::OpaqueTy(OpaqueTy {
2196 let bounds_predicates = ty::print::with_no_queries(|| {
2197 let substs = InternalSubsts::identity_for_item(tcx, def_id);
2198 let opaque_ty = tcx.mk_opaque(def_id, substs);
2200 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
2201 let bounds = AstConv::compute_bounds(
2205 SizedByDefault::Yes,
2206 tcx.def_span(def_id),
2209 bounds.predicates(tcx, opaque_ty)
2211 if impl_trait_fn.is_some() {
2213 return ty::GenericPredicates {
2215 predicates: tcx.arena.alloc_from_iter(bounds_predicates),
2218 // named opaque types
2219 predicates.extend(bounds_predicates);
2228 Node::ForeignItem(item) => match item.kind {
2229 ForeignItemKind::Static(..) => NO_GENERICS,
2230 ForeignItemKind::Fn(_, _, ref generics) => generics,
2231 ForeignItemKind::Type => NO_GENERICS,
2237 let generics = tcx.generics_of(def_id);
2238 let parent_count = generics.parent_count as u32;
2239 let has_own_self = generics.has_self && parent_count == 0;
2241 // Below we'll consider the bounds on the type parameters (including `Self`)
2242 // and the explicit where-clauses, but to get the full set of predicates
2243 // on a trait we need to add in the supertrait bounds and bounds found on
2244 // associated types.
2245 if let Some((_trait_ref, _)) = is_trait {
2246 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2249 // In default impls, we can assume that the self type implements
2250 // the trait. So in:
2252 // default impl Foo for Bar { .. }
2254 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2255 // (see below). Recall that a default impl is not itself an impl, but rather a
2256 // set of defaults that can be incorporated into another impl.
2257 if let Some(trait_ref) = is_default_impl_trait {
2259 trait_ref.to_poly_trait_ref().without_const().to_predicate(),
2260 tcx.def_span(def_id),
2264 // Collect the region predicates that were declared inline as
2265 // well. In the case of parameters declared on a fn or method, we
2266 // have to be careful to only iterate over early-bound regions.
2267 let mut index = parent_count + has_own_self as u32;
2268 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2269 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2270 def_id: tcx.hir().local_def_id(param.hir_id),
2272 name: param.name.ident().name,
2277 GenericParamKind::Lifetime { .. } => {
2278 param.bounds.iter().for_each(|bound| match bound {
2279 hir::GenericBound::Outlives(lt) => {
2280 let bound = AstConv::ast_region_to_region(&icx, <, None);
2281 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2282 predicates.push((outlives.to_predicate(), lt.span));
2291 // Collect the predicates that were written inline by the user on each
2292 // type parameter (e.g., `<T: Foo>`).
2293 for param in ast_generics.params {
2294 if let GenericParamKind::Type { .. } = param.kind {
2295 let name = param.name.ident().name;
2296 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2299 let sized = SizedByDefault::Yes;
2300 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2301 predicates.extend(bounds.predicates(tcx, param_ty));
2305 // Add in the bounds that appear in the where-clause.
2306 let where_clause = &ast_generics.where_clause;
2307 for predicate in where_clause.predicates {
2309 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2310 let ty = icx.to_ty(&bound_pred.bounded_ty);
2312 // Keep the type around in a dummy predicate, in case of no bounds.
2313 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2314 // is still checked for WF.
2315 if bound_pred.bounds.is_empty() {
2316 if let ty::Param(_) = ty.kind {
2317 // This is a `where T:`, which can be in the HIR from the
2318 // transformation that moves `?Sized` to `T`'s declaration.
2319 // We can skip the predicate because type parameters are
2320 // trivially WF, but also we *should*, to avoid exposing
2321 // users who never wrote `where Type:,` themselves, to
2322 // compiler/tooling bugs from not handling WF predicates.
2324 let span = bound_pred.bounded_ty.span;
2325 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2327 ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)),
2333 for bound in bound_pred.bounds.iter() {
2335 &hir::GenericBound::Trait(ref poly_trait_ref, modifier) => {
2336 let constness = match modifier {
2337 hir::TraitBoundModifier::MaybeConst => ast::Constness::NotConst,
2338 hir::TraitBoundModifier::None => constness,
2339 hir::TraitBoundModifier::Maybe => bug!("this wasn't handled"),
2342 let mut bounds = Bounds::default();
2343 let _ = AstConv::instantiate_poly_trait_ref(
2350 predicates.extend(bounds.predicates(tcx, ty));
2353 &hir::GenericBound::Outlives(ref lifetime) => {
2354 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2355 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2356 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2362 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2363 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2364 predicates.extend(region_pred.bounds.iter().map(|bound| {
2365 let (r2, span) = match bound {
2366 hir::GenericBound::Outlives(lt) => {
2367 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2371 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2373 (ty::Predicate::RegionOutlives(pred), span)
2377 &hir::WherePredicate::EqPredicate(..) => {
2383 // Add predicates from associated type bounds.
2384 if let Some((self_trait_ref, trait_items)) = is_trait {
2385 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2386 associated_item_predicates(tcx, def_id, self_trait_ref, trait_item_ref)
2390 let mut predicates = predicates.predicates;
2392 // Subtle: before we store the predicates into the tcx, we
2393 // sort them so that predicates like `T: Foo<Item=U>` come
2394 // before uses of `U`. This avoids false ambiguity errors
2395 // in trait checking. See `setup_constraining_predicates`
2397 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2398 let self_ty = tcx.type_of(def_id);
2399 let trait_ref = tcx.impl_trait_ref(def_id);
2400 cgp::setup_constraining_predicates(
2404 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2408 let result = ty::GenericPredicates {
2409 parent: generics.parent,
2410 predicates: tcx.arena.alloc_from_iter(predicates),
2412 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2416 fn associated_item_predicates(
2419 self_trait_ref: ty::TraitRef<'tcx>,
2420 trait_item_ref: &hir::TraitItemRef,
2421 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2422 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2423 let item_def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
2424 let bounds = match trait_item.kind {
2425 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2426 _ => return Vec::new(),
2429 let is_gat = !tcx.generics_of(item_def_id).params.is_empty();
2431 let mut had_error = false;
2433 let mut unimplemented_error = |arg_kind: &str| {
2438 &format!("{}-generic associated types are not yet implemented", arg_kind),
2440 .note("for more information, see https://github.com/rust-lang/rust/issues/44265")
2446 let mk_bound_param = |param: &ty::GenericParamDef, _: &_| {
2448 ty::GenericParamDefKind::Lifetime => tcx
2449 .mk_region(ty::RegionKind::ReLateBound(
2451 ty::BoundRegion::BrNamed(param.def_id, param.name),
2454 // FIXME(generic_associated_types): Use bound types and constants
2455 // once they are handled by the trait system.
2456 ty::GenericParamDefKind::Type { .. } => {
2457 unimplemented_error("type");
2458 tcx.types.err.into()
2460 ty::GenericParamDefKind::Const => {
2461 unimplemented_error("const");
2462 tcx.consts.err.into()
2467 let bound_substs = if is_gat {
2470 // trait X<'a, B, const C: usize> {
2471 // type T<'d, E, const F: usize>: Default;
2474 // We need to create predicates on the trait:
2476 // for<'d, E, const F: usize>
2477 // <Self as X<'a, B, const C: usize>>::T<'d, E, const F: usize>: Sized + Default
2479 // We substitute escaping bound parameters for the generic
2480 // arguments to the associated type which are then bound by
2481 // the `Binder` around the the predicate.
2483 // FIXME(generic_associated_types): Currently only lifetimes are handled.
2484 self_trait_ref.substs.extend_to(tcx, item_def_id, mk_bound_param)
2486 self_trait_ref.substs
2489 let assoc_ty = tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id), bound_substs);
2491 let bounds = AstConv::compute_bounds(
2492 &ItemCtxt::new(tcx, def_id),
2495 SizedByDefault::Yes,
2499 let predicates = bounds.predicates(tcx, assoc_ty);
2502 // We use shifts to get the regions that we're substituting to
2503 // be bound by the binders in the `Predicate`s rather that
2505 let shifted_in = ty::fold::shift_vars(tcx, &predicates, 1);
2506 let substituted = shifted_in.subst(tcx, bound_substs);
2507 ty::fold::shift_out_vars(tcx, &substituted, 1)
2513 /// Converts a specific `GenericBound` from the AST into a set of
2514 /// predicates that apply to the self type. A vector is returned
2515 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2516 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2517 /// and `<T as Bar>::X == i32`).
2518 fn predicates_from_bound<'tcx>(
2519 astconv: &dyn AstConv<'tcx>,
2521 bound: &'tcx hir::GenericBound<'tcx>,
2522 constness: ast::Constness,
2523 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2525 hir::GenericBound::Trait(ref tr, modifier) => {
2526 let constness = match modifier {
2527 hir::TraitBoundModifier::Maybe => return vec![],
2528 hir::TraitBoundModifier::MaybeConst => ast::Constness::NotConst,
2529 hir::TraitBoundModifier::None => constness,
2532 let mut bounds = Bounds::default();
2533 let _ = astconv.instantiate_poly_trait_ref(tr, constness, param_ty, &mut bounds);
2534 bounds.predicates(astconv.tcx(), param_ty)
2536 hir::GenericBound::Outlives(ref lifetime) => {
2537 let region = astconv.ast_region_to_region(lifetime, None);
2538 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2539 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2544 fn compute_sig_of_foreign_fn_decl<'tcx>(
2547 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).as_str())
2553 hir::Unsafety::Unsafe
2555 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl, &[], None);
2557 // Feature gate SIMD types in FFI, since I am not sure that the
2558 // ABIs are handled at all correctly. -huonw
2559 if abi != abi::Abi::RustIntrinsic
2560 && abi != abi::Abi::PlatformIntrinsic
2561 && !tcx.features().simd_ffi
2563 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2569 "use of SIMD type `{}` in FFI is highly experimental and \
2570 may result in invalid code",
2571 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2574 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2578 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2581 if let hir::FunctionRetTy::Return(ref ty) = decl.output {
2582 check(&ty, *fty.output().skip_binder())
2589 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2590 match tcx.hir().get_if_local(def_id) {
2591 Some(Node::ForeignItem(..)) => true,
2593 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2597 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2598 match tcx.hir().get_if_local(def_id) {
2599 Some(Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. }))
2600 | Some(Node::ForeignItem(&hir::ForeignItem {
2601 kind: hir::ForeignItemKind::Static(_, mutbl),
2605 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2609 fn from_target_feature(
2612 attr: &ast::Attribute,
2613 whitelist: &FxHashMap<String, Option<Symbol>>,
2614 target_features: &mut Vec<Symbol>,
2616 let list = match attr.meta_item_list() {
2620 let bad_item = |span| {
2621 let msg = "malformed `target_feature` attribute input";
2622 let code = "enable = \"..\"".to_owned();
2624 .struct_span_err(span, &msg)
2625 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2628 let rust_features = tcx.features();
2630 // Only `enable = ...` is accepted in the meta-item list.
2631 if !item.check_name(sym::enable) {
2632 bad_item(item.span());
2636 // Must be of the form `enable = "..."` (a string).
2637 let value = match item.value_str() {
2638 Some(value) => value,
2640 bad_item(item.span());
2645 // We allow comma separation to enable multiple features.
2646 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2647 // Only allow whitelisted features per platform.
2648 let feature_gate = match whitelist.get(feature) {
2652 format!("the feature named `{}` is not valid for this target", feature);
2653 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2656 format!("`{}` is not valid for this target", feature),
2658 if feature.starts_with("+") {
2659 let valid = whitelist.contains_key(&feature[1..]);
2661 err.help("consider removing the leading `+` in the feature name");
2669 // Only allow features whose feature gates have been enabled.
2670 let allowed = match feature_gate.as_ref().map(|s| *s) {
2671 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2672 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2673 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2674 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2675 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2676 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2677 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2678 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2679 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2680 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2681 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2682 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2683 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2684 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2685 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2686 Some(name) => bug!("unknown target feature gate {}", name),
2689 if !allowed && id.is_local() {
2691 &tcx.sess.parse_sess,
2692 feature_gate.unwrap(),
2694 &format!("the target feature `{}` is currently unstable", feature),
2698 Some(Symbol::intern(feature))
2703 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2704 use rustc::mir::mono::Linkage::*;
2706 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2707 // applicable to variable declarations and may not really make sense for
2708 // Rust code in the first place but whitelist them anyway and trust that
2709 // the user knows what s/he's doing. Who knows, unanticipated use cases
2710 // may pop up in the future.
2712 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2713 // and don't have to be, LLVM treats them as no-ops.
2715 "appending" => Appending,
2716 "available_externally" => AvailableExternally,
2718 "extern_weak" => ExternalWeak,
2719 "external" => External,
2720 "internal" => Internal,
2721 "linkonce" => LinkOnceAny,
2722 "linkonce_odr" => LinkOnceODR,
2723 "private" => Private,
2725 "weak_odr" => WeakODR,
2727 let span = tcx.hir().span_if_local(def_id);
2728 if let Some(span) = span {
2729 tcx.sess.span_fatal(span, "invalid linkage specified")
2731 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2737 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2738 let attrs = tcx.get_attrs(id);
2740 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2742 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2744 let mut inline_span = None;
2745 let mut link_ordinal_span = None;
2746 for attr in attrs.iter() {
2747 if attr.check_name(sym::cold) {
2748 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2749 } else if attr.check_name(sym::rustc_allocator) {
2750 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2751 } else if attr.check_name(sym::unwind) {
2752 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2753 } else if attr.check_name(sym::ffi_returns_twice) {
2754 if tcx.is_foreign_item(id) {
2755 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2757 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2762 "`#[ffi_returns_twice]` may only be used on foreign functions"
2766 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2767 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2768 } else if attr.check_name(sym::naked) {
2769 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2770 } else if attr.check_name(sym::no_mangle) {
2771 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2772 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2773 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2774 } else if attr.check_name(sym::no_debug) {
2775 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2776 } else if attr.check_name(sym::used) {
2777 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2778 } else if attr.check_name(sym::thread_local) {
2779 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2780 } else if attr.check_name(sym::track_caller) {
2781 if tcx.fn_sig(id).abi() != abi::Abi::Rust {
2782 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2785 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2786 } else if attr.check_name(sym::export_name) {
2787 if let Some(s) = attr.value_str() {
2788 if s.as_str().contains("\0") {
2789 // `#[export_name = ...]` will be converted to a null-terminated string,
2790 // so it may not contain any null characters.
2795 "`export_name` may not contain null characters"
2799 codegen_fn_attrs.export_name = Some(s);
2801 } else if attr.check_name(sym::target_feature) {
2802 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2803 let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
2805 .struct_span_err(attr.span, msg)
2806 .span_label(attr.span, "can only be applied to `unsafe` functions")
2807 .span_label(tcx.def_span(id), "not an `unsafe` function")
2810 from_target_feature(tcx, id, attr, &whitelist, &mut codegen_fn_attrs.target_features);
2811 } else if attr.check_name(sym::linkage) {
2812 if let Some(val) = attr.value_str() {
2813 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2815 } else if attr.check_name(sym::link_section) {
2816 if let Some(val) = attr.value_str() {
2817 if val.as_str().bytes().any(|b| b == 0) {
2819 "illegal null byte in link_section \
2823 tcx.sess.span_err(attr.span, &msg);
2825 codegen_fn_attrs.link_section = Some(val);
2828 } else if attr.check_name(sym::link_name) {
2829 codegen_fn_attrs.link_name = attr.value_str();
2830 } else if attr.check_name(sym::link_ordinal) {
2831 link_ordinal_span = Some(attr.span);
2832 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2833 codegen_fn_attrs.link_ordinal = ordinal;
2838 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2839 if !attr.has_name(sym::inline) {
2842 match attr.meta().map(|i| i.kind) {
2843 Some(MetaItemKind::Word) => {
2847 Some(MetaItemKind::List(ref items)) => {
2849 inline_span = Some(attr.span);
2850 if items.len() != 1 {
2852 tcx.sess.diagnostic(),
2855 "expected one argument"
2859 } else if list_contains_name(&items[..], sym::always) {
2861 } else if list_contains_name(&items[..], sym::never) {
2865 tcx.sess.diagnostic(),
2875 Some(MetaItemKind::NameValue(_)) => ia,
2880 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2881 if !attr.has_name(sym::optimize) {
2884 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
2885 match attr.meta().map(|i| i.kind) {
2886 Some(MetaItemKind::Word) => {
2887 err(attr.span, "expected one argument");
2890 Some(MetaItemKind::List(ref items)) => {
2892 inline_span = Some(attr.span);
2893 if items.len() != 1 {
2894 err(attr.span, "expected one argument");
2896 } else if list_contains_name(&items[..], sym::size) {
2898 } else if list_contains_name(&items[..], sym::speed) {
2901 err(items[0].span(), "invalid argument");
2905 Some(MetaItemKind::NameValue(_)) => ia,
2910 // If a function uses #[target_feature] it can't be inlined into general
2911 // purpose functions as they wouldn't have the right target features
2912 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2915 if codegen_fn_attrs.target_features.len() > 0 {
2916 if codegen_fn_attrs.inline == InlineAttr::Always {
2917 if let Some(span) = inline_span {
2920 "cannot use `#[inline(always)]` with \
2921 `#[target_feature]`",
2927 // Weak lang items have the same semantics as "std internal" symbols in the
2928 // sense that they're preserved through all our LTO passes and only
2929 // strippable by the linker.
2931 // Additionally weak lang items have predetermined symbol names.
2932 if tcx.is_weak_lang_item(id) {
2933 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2935 if let Some(name) = weak_lang_items::link_name(&attrs) {
2936 codegen_fn_attrs.export_name = Some(name);
2937 codegen_fn_attrs.link_name = Some(name);
2939 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
2941 // Internal symbols to the standard library all have no_mangle semantics in
2942 // that they have defined symbol names present in the function name. This
2943 // also applies to weak symbols where they all have known symbol names.
2944 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2945 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2951 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
2952 use syntax::ast::{Lit, LitIntType, LitKind};
2953 let meta_item_list = attr.meta_item_list();
2954 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
2955 let sole_meta_list = match meta_item_list {
2956 Some([item]) => item.literal(),
2959 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
2960 if *ordinal <= std::usize::MAX as u128 {
2961 Some(*ordinal as usize)
2963 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
2965 .struct_span_err(attr.span, &msg)
2966 .note("the value may not exceed `std::usize::MAX`")
2972 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
2973 .note("an unsuffixed integer value, e.g., `1`, is expected")
2979 fn check_link_name_xor_ordinal(
2981 codegen_fn_attrs: &CodegenFnAttrs,
2982 inline_span: Option<Span>,
2984 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
2987 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
2988 if let Some(span) = inline_span {
2989 tcx.sess.span_err(span, msg);