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::constrained_generic_params as cgp;
19 use crate::check::intrinsic::intrisic_operation_unsafety;
21 use crate::middle::resolve_lifetime as rl;
22 use crate::middle::weak_lang_items;
23 use rustc::mir::mono::Linkage;
24 use rustc::ty::query::Providers;
25 use rustc::ty::subst::{Subst, InternalSubsts};
26 use rustc::ty::util::Discr;
27 use rustc::ty::util::IntTypeExt;
28 use rustc::ty::subst::UnpackedKind;
29 use rustc::ty::{self, AdtKind, DefIdTree, ToPolyTraitRef, Ty, TyCtxt, Const};
30 use rustc::ty::{ReprOptions, ToPredicate};
31 use rustc::util::captures::Captures;
32 use rustc::util::nodemap::FxHashMap;
33 use rustc_target::spec::abi;
36 use syntax::ast::{Ident, MetaItemKind};
37 use syntax::attr::{InlineAttr, OptimizeAttr, list_contains_name, mark_used};
38 use syntax::source_map::Spanned;
39 use syntax::feature_gate;
40 use syntax::symbol::{InternedString, kw, Symbol, sym};
41 use syntax_pos::{Span, DUMMY_SP};
43 use rustc::hir::def::{CtorKind, Res, DefKind};
45 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
46 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
47 use rustc::hir::GenericParamKind;
48 use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
50 use errors::{Applicability, DiagnosticId};
54 struct OnlySelfBounds(bool);
56 ///////////////////////////////////////////////////////////////////////////
59 fn collect_mod_item_types<'tcx>(tcx: TyCtxt<'tcx>, module_def_id: DefId) {
60 tcx.hir().visit_item_likes_in_module(
62 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor()
66 pub fn provide(providers: &mut Providers<'_>) {
67 *providers = Providers {
71 predicates_defined_on,
72 explicit_predicates_of,
74 type_param_predicates,
83 collect_mod_item_types,
88 ///////////////////////////////////////////////////////////////////////////
90 /// Context specific to some particular item. This is what implements
91 /// `AstConv`. It has information about the predicates that are defined
92 /// on the trait. Unfortunately, this predicate information is
93 /// available in various different forms at various points in the
94 /// process. So we can't just store a pointer to e.g., the AST or the
95 /// parsed ty form, we have to be more flexible. To this end, the
96 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
97 /// `get_type_parameter_bounds` requests, drawing the information from
98 /// the AST (`hir::Generics`), recursively.
99 pub struct ItemCtxt<'tcx> {
104 ///////////////////////////////////////////////////////////////////////////
106 struct CollectItemTypesVisitor<'tcx> {
110 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
111 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
112 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
115 fn visit_item(&mut self, item: &'tcx hir::Item) {
116 convert_item(self.tcx, item.hir_id);
117 intravisit::walk_item(self, item);
120 fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
121 for param in &generics.params {
123 hir::GenericParamKind::Lifetime { .. } => {}
124 hir::GenericParamKind::Type {
127 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
128 self.tcx.type_of(def_id);
130 hir::GenericParamKind::Type { .. } => {}
131 hir::GenericParamKind::Const { .. } => {
132 let def_id = self.tcx.hir().local_def_id_from_hir_id(param.hir_id);
133 self.tcx.type_of(def_id);
137 intravisit::walk_generics(self, generics);
140 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
141 if let hir::ExprKind::Closure(..) = expr.node {
142 let def_id = self.tcx.hir().local_def_id_from_hir_id(expr.hir_id);
143 self.tcx.generics_of(def_id);
144 self.tcx.type_of(def_id);
146 intravisit::walk_expr(self, expr);
149 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
150 convert_trait_item(self.tcx, trait_item.hir_id);
151 intravisit::walk_trait_item(self, trait_item);
154 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
155 convert_impl_item(self.tcx, impl_item.hir_id);
156 intravisit::walk_impl_item(self, impl_item);
160 ///////////////////////////////////////////////////////////////////////////
161 // Utility types and common code for the above passes.
163 impl ItemCtxt<'tcx> {
164 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
165 ItemCtxt { tcx, item_def_id }
168 pub fn to_ty(&self, ast_ty: &'tcx hir::Ty) -> Ty<'tcx> {
169 AstConv::ast_ty_to_ty(self, ast_ty)
173 impl AstConv<'tcx> for ItemCtxt<'tcx> {
174 fn tcx(&self) -> TyCtxt<'tcx> {
178 fn get_type_parameter_bounds(&self, span: Span, def_id: DefId)
179 -> &'tcx ty::GenericPredicates<'tcx> {
182 .type_param_predicates((self.item_def_id, def_id))
187 _: Option<&ty::GenericParamDef>,
189 ) -> Option<ty::Region<'tcx>> {
193 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
194 self.tcx().sess.struct_span_err_with_code(
196 "the type placeholder `_` is not allowed within types on item signatures",
197 DiagnosticId::Error("E0121".into()),
198 ).span_label(span, "not allowed in type signatures")
207 _: Option<&ty::GenericParamDef>,
209 ) -> &'tcx Const<'tcx> {
210 self.tcx().sess.struct_span_err_with_code(
212 "the const placeholder `_` is not allowed within types on item signatures",
213 DiagnosticId::Error("E0121".into()),
214 ).span_label(span, "not allowed in type signatures")
217 self.tcx().consts.err
220 fn projected_ty_from_poly_trait_ref(
224 poly_trait_ref: ty::PolyTraitRef<'tcx>,
226 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
227 self.tcx().mk_projection(item_def_id, trait_ref.substs)
229 // no late-bound regions, we can just ignore the binder
234 "cannot extract an associated type from a higher-ranked trait bound \
241 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
242 // types in item signatures are not normalized, to avoid undue
247 fn set_tainted_by_errors(&self) {
248 // no obvious place to track this, so just let it go
251 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
252 // no place to record types from signatures?
256 fn type_param_predicates<'tcx>(
258 (item_def_id, def_id): (DefId, DefId),
259 ) -> &'tcx ty::GenericPredicates<'tcx> {
262 // In the AST, bounds can derive from two places. Either
263 // written inline like `<T : Foo>` or in a where clause like
266 let param_id = tcx.hir().as_local_hir_id(def_id).unwrap();
267 let param_owner = tcx.hir().ty_param_owner(param_id);
268 let param_owner_def_id = tcx.hir().local_def_id_from_hir_id(param_owner);
269 let generics = tcx.generics_of(param_owner_def_id);
270 let index = generics.param_def_id_to_index[&def_id];
271 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id).as_interned_str());
273 // Don't look for bounds where the type parameter isn't in scope.
274 let parent = if item_def_id == param_owner_def_id {
277 tcx.generics_of(item_def_id).parent
280 let result = parent.map_or(&tcx.common.empty_predicates, |parent| {
281 let icx = ItemCtxt::new(tcx, parent);
282 icx.get_type_parameter_bounds(DUMMY_SP, def_id)
284 let mut extend = None;
286 let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
287 let ast_generics = match tcx.hir().get(item_hir_id) {
288 Node::TraitItem(item) => &item.generics,
290 Node::ImplItem(item) => &item.generics,
292 Node::Item(item) => {
294 ItemKind::Fn(.., ref generics, _)
295 | ItemKind::Impl(_, _, _, ref generics, ..)
296 | ItemKind::Ty(_, ref generics)
297 | ItemKind::Existential(ExistTy {
302 | ItemKind::Enum(_, ref generics)
303 | ItemKind::Struct(_, ref generics)
304 | ItemKind::Union(_, ref generics) => generics,
305 ItemKind::Trait(_, _, ref generics, ..) => {
306 // Implied `Self: Trait` and supertrait bounds.
307 if param_id == item_hir_id {
308 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
309 extend = Some((identity_trait_ref.to_predicate(), item.span));
317 Node::ForeignItem(item) => match item.node {
318 ForeignItemKind::Fn(_, _, ref generics) => generics,
325 let icx = ItemCtxt::new(tcx, item_def_id);
326 let mut result = (*result).clone();
327 result.predicates.extend(extend.into_iter());
329 .extend(icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty,
330 OnlySelfBounds(true)));
331 tcx.arena.alloc(result)
334 impl ItemCtxt<'tcx> {
335 /// Finds bounds from `hir::Generics`. This requires scanning through the
336 /// AST. We do this to avoid having to convert *all* the bounds, which
337 /// would create artificial cycles. Instead we can only convert the
338 /// bounds for a type parameter `X` if `X::Foo` is used.
339 fn type_parameter_bounds_in_generics(
341 ast_generics: &'tcx hir::Generics,
342 param_id: hir::HirId,
344 only_self_bounds: OnlySelfBounds,
345 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
346 let from_ty_params = ast_generics
349 .filter_map(|param| match param.kind {
350 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
353 .flat_map(|bounds| bounds.iter())
354 .flat_map(|b| predicates_from_bound(self, ty, b));
356 let from_where_clauses = ast_generics
360 .filter_map(|wp| match *wp {
361 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
365 let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
367 } else if !only_self_bounds.0 {
368 Some(self.to_ty(&bp.bounded_ty))
372 bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
374 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
376 from_ty_params.chain(from_where_clauses).collect()
380 /// Tests whether this is the AST for a reference to the type
381 /// parameter with ID `param_id`. We use this so as to avoid running
382 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
383 /// conversion of the type to avoid inducing unnecessary cycles.
384 fn is_param<'tcx>(tcx: TyCtxt<'tcx>, ast_ty: &hir::Ty, param_id: hir::HirId) -> bool {
385 if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.node {
387 Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
388 def_id == tcx.hir().local_def_id_from_hir_id(param_id)
397 fn convert_item<'tcx>(tcx: TyCtxt<'tcx>, item_id: hir::HirId) {
398 let it = tcx.hir().expect_item(item_id);
399 debug!("convert: item {} with id {}", it.ident, it.hir_id);
400 let def_id = tcx.hir().local_def_id_from_hir_id(item_id);
402 // These don't define types.
403 hir::ItemKind::ExternCrate(_)
404 | hir::ItemKind::Use(..)
405 | hir::ItemKind::Mod(_)
406 | hir::ItemKind::GlobalAsm(_) => {}
407 hir::ItemKind::ForeignMod(ref foreign_mod) => {
408 for item in &foreign_mod.items {
409 let def_id = tcx.hir().local_def_id_from_hir_id(item.hir_id);
410 tcx.generics_of(def_id);
412 tcx.predicates_of(def_id);
413 if let hir::ForeignItemKind::Fn(..) = item.node {
418 hir::ItemKind::Enum(ref enum_definition, _) => {
419 tcx.generics_of(def_id);
421 tcx.predicates_of(def_id);
422 convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
424 hir::ItemKind::Impl(..) => {
425 tcx.generics_of(def_id);
427 tcx.impl_trait_ref(def_id);
428 tcx.predicates_of(def_id);
430 hir::ItemKind::Trait(..) => {
431 tcx.generics_of(def_id);
432 tcx.trait_def(def_id);
433 tcx.at(it.span).super_predicates_of(def_id);
434 tcx.predicates_of(def_id);
436 hir::ItemKind::TraitAlias(..) => {
437 tcx.generics_of(def_id);
438 tcx.at(it.span).super_predicates_of(def_id);
439 tcx.predicates_of(def_id);
441 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
442 tcx.generics_of(def_id);
444 tcx.predicates_of(def_id);
446 for f in struct_def.fields() {
447 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
448 tcx.generics_of(def_id);
450 tcx.predicates_of(def_id);
453 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
454 convert_variant_ctor(tcx, ctor_hir_id);
458 // Desugared from `impl Trait`, so visited by the function's return type.
459 hir::ItemKind::Existential(hir::ExistTy {
460 impl_trait_fn: Some(_),
464 hir::ItemKind::Existential(..)
465 | hir::ItemKind::Ty(..)
466 | hir::ItemKind::Static(..)
467 | hir::ItemKind::Const(..)
468 | hir::ItemKind::Fn(..) => {
469 tcx.generics_of(def_id);
471 tcx.predicates_of(def_id);
472 if let hir::ItemKind::Fn(..) = it.node {
479 fn convert_trait_item<'tcx>(tcx: TyCtxt<'tcx>, trait_item_id: hir::HirId) {
480 let trait_item = tcx.hir().expect_trait_item(trait_item_id);
481 let def_id = tcx.hir().local_def_id_from_hir_id(trait_item.hir_id);
482 tcx.generics_of(def_id);
484 match trait_item.node {
485 hir::TraitItemKind::Const(..)
486 | hir::TraitItemKind::Type(_, Some(_))
487 | hir::TraitItemKind::Method(..) => {
489 if let hir::TraitItemKind::Method(..) = trait_item.node {
494 hir::TraitItemKind::Type(_, None) => {}
497 tcx.predicates_of(def_id);
500 fn convert_impl_item<'tcx>(tcx: TyCtxt<'tcx>, impl_item_id: hir::HirId) {
501 let def_id = tcx.hir().local_def_id_from_hir_id(impl_item_id);
502 tcx.generics_of(def_id);
504 tcx.predicates_of(def_id);
505 if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).node {
510 fn convert_variant_ctor<'tcx>(tcx: TyCtxt<'tcx>, ctor_id: hir::HirId) {
511 let def_id = tcx.hir().local_def_id_from_hir_id(ctor_id);
512 tcx.generics_of(def_id);
514 tcx.predicates_of(def_id);
517 fn convert_enum_variant_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, variants: &[hir::Variant]) {
518 let def = tcx.adt_def(def_id);
519 let repr_type = def.repr.discr_type();
520 let initial = repr_type.initial_discriminant(tcx);
521 let mut prev_discr = None::<Discr<'tcx>>;
523 // fill the discriminant values and field types
524 for variant in variants {
525 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
527 if let Some(ref e) = variant.node.disr_expr {
528 let expr_did = tcx.hir().local_def_id_from_hir_id(e.hir_id);
529 def.eval_explicit_discr(tcx, expr_did)
530 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
537 "enum discriminant overflowed"
540 format!("overflowed on value after {}", prev_discr.unwrap()),
542 "explicitly set `{} = {}` if that is desired outcome",
543 variant.node.ident, wrapped_discr
547 }.unwrap_or(wrapped_discr),
550 for f in variant.node.data.fields() {
551 let def_id = tcx.hir().local_def_id_from_hir_id(f.hir_id);
552 tcx.generics_of(def_id);
554 tcx.predicates_of(def_id);
557 // Convert the ctor, if any. This also registers the variant as
559 if let Some(ctor_hir_id) = variant.node.data.ctor_hir_id() {
560 convert_variant_ctor(tcx, ctor_hir_id);
565 fn convert_variant<'tcx>(
567 variant_did: Option<DefId>,
568 ctor_did: Option<DefId>,
570 discr: ty::VariantDiscr,
571 def: &hir::VariantData,
572 adt_kind: ty::AdtKind,
574 ) -> ty::VariantDef {
575 let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
576 let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
581 let fid = tcx.hir().local_def_id_from_hir_id(f.hir_id);
582 let dup_span = seen_fields.get(&f.ident.modern()).cloned();
583 if let Some(prev_span) = dup_span {
588 "field `{}` is already declared",
590 ).span_label(f.span, "field already declared")
591 .span_label(prev_span, format!("`{}` first declared here", f.ident))
594 seen_fields.insert(f.ident.modern(), f.span);
600 vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
604 let recovered = match def {
605 hir::VariantData::Struct(_, r) => *r,
615 CtorKind::from_hir(def),
622 fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx ty::AdtDef {
625 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
626 let item = match tcx.hir().get(hir_id) {
627 Node::Item(item) => item,
631 let repr = ReprOptions::new(tcx, def_id);
632 let (kind, variants) = match item.node {
633 ItemKind::Enum(ref def, _) => {
634 let mut distance_from_explicit = 0;
635 let variants = def.variants
638 let variant_did = Some(tcx.hir().local_def_id_from_hir_id(v.node.id));
639 let ctor_did = v.node.data.ctor_hir_id()
640 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
642 let discr = if let Some(ref e) = v.node.disr_expr {
643 distance_from_explicit = 0;
644 ty::VariantDiscr::Explicit(tcx.hir().local_def_id_from_hir_id(e.hir_id))
646 ty::VariantDiscr::Relative(distance_from_explicit)
648 distance_from_explicit += 1;
650 convert_variant(tcx, variant_did, ctor_did, v.node.ident, discr,
651 &v.node.data, AdtKind::Enum, def_id)
655 (AdtKind::Enum, variants)
657 ItemKind::Struct(ref def, _) => {
658 let variant_did = None;
659 let ctor_did = def.ctor_hir_id()
660 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
662 let variants = std::iter::once(convert_variant(
663 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
664 AdtKind::Struct, def_id,
667 (AdtKind::Struct, variants)
669 ItemKind::Union(ref def, _) => {
670 let variant_did = None;
671 let ctor_did = def.ctor_hir_id()
672 .map(|hir_id| tcx.hir().local_def_id_from_hir_id(hir_id));
674 let variants = std::iter::once(convert_variant(
675 tcx, variant_did, ctor_did, item.ident, ty::VariantDiscr::Relative(0), def,
676 AdtKind::Union, def_id,
679 (AdtKind::Union, variants)
683 tcx.alloc_adt_def(def_id, kind, variants, repr)
686 /// Ensures that the super-predicates of the trait with a `DefId`
687 /// of `trait_def_id` are converted and stored. This also ensures that
688 /// the transitive super-predicates are converted.
689 fn super_predicates_of<'tcx>(
692 ) -> &'tcx ty::GenericPredicates<'tcx> {
693 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
694 let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id).unwrap();
696 let item = match tcx.hir().get(trait_hir_id) {
697 Node::Item(item) => item,
698 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
701 let (generics, bounds) = match item.node {
702 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
703 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
704 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
707 let icx = ItemCtxt::new(tcx, trait_def_id);
709 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
710 let self_param_ty = tcx.mk_self_type();
711 let superbounds1 = AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No,
714 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
716 // Convert any explicit superbounds in the where-clause,
717 // e.g., `trait Foo where Self: Bar`.
718 // In the case of trait aliases, however, we include all bounds in the where-clause,
719 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
720 // as one of its "superpredicates".
721 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
722 let superbounds2 = icx.type_parameter_bounds_in_generics(
723 generics, item.hir_id, self_param_ty, OnlySelfBounds(!is_trait_alias));
725 // Combine the two lists to form the complete set of superbounds:
726 let superbounds: Vec<_> = superbounds1.into_iter().chain(superbounds2).collect();
728 // Now require that immediate supertraits are converted,
729 // which will, in turn, reach indirect supertraits.
730 for &(pred, span) in &superbounds {
731 debug!("superbound: {:?}", pred);
732 if let ty::Predicate::Trait(bound) = pred {
733 tcx.at(span).super_predicates_of(bound.def_id());
737 tcx.arena.alloc(ty::GenericPredicates {
739 predicates: superbounds,
743 fn trait_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx ty::TraitDef {
744 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
745 let item = tcx.hir().expect_item(hir_id);
747 let (is_auto, unsafety) = match item.node {
748 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
749 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
750 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
753 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
754 if paren_sugar && !tcx.features().unboxed_closures {
755 let mut err = tcx.sess.struct_span_err(
757 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
758 which traits can use parenthetical notation",
762 "add `#![feature(unboxed_closures)]` to \
763 the crate attributes to use it"
768 let is_marker = tcx.has_attr(def_id, sym::marker);
769 let def_path_hash = tcx.def_path_hash(def_id);
770 let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
774 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
775 struct LateBoundRegionsDetector<'tcx> {
777 outer_index: ty::DebruijnIndex,
778 has_late_bound_regions: Option<Span>,
781 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
782 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
783 NestedVisitorMap::None
786 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
787 if self.has_late_bound_regions.is_some() {
791 hir::TyKind::BareFn(..) => {
792 self.outer_index.shift_in(1);
793 intravisit::walk_ty(self, ty);
794 self.outer_index.shift_out(1);
796 _ => intravisit::walk_ty(self, ty),
800 fn visit_poly_trait_ref(
802 tr: &'tcx hir::PolyTraitRef,
803 m: hir::TraitBoundModifier,
805 if self.has_late_bound_regions.is_some() {
808 self.outer_index.shift_in(1);
809 intravisit::walk_poly_trait_ref(self, tr, m);
810 self.outer_index.shift_out(1);
813 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
814 if self.has_late_bound_regions.is_some() {
818 match self.tcx.named_region(lt.hir_id) {
819 Some(rl::Region::Static) | Some(rl::Region::EarlyBound(..)) => {}
820 Some(rl::Region::LateBound(debruijn, _, _))
821 | Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
822 Some(rl::Region::LateBound(..))
823 | Some(rl::Region::LateBoundAnon(..))
824 | Some(rl::Region::Free(..))
826 self.has_late_bound_regions = Some(lt.span);
832 fn has_late_bound_regions<'tcx>(
834 generics: &'tcx hir::Generics,
835 decl: &'tcx hir::FnDecl,
837 let mut visitor = LateBoundRegionsDetector {
839 outer_index: ty::INNERMOST,
840 has_late_bound_regions: None,
842 for param in &generics.params {
843 if let GenericParamKind::Lifetime { .. } = param.kind {
844 if tcx.is_late_bound(param.hir_id) {
845 return Some(param.span);
849 visitor.visit_fn_decl(decl);
850 visitor.has_late_bound_regions
854 Node::TraitItem(item) => match item.node {
855 hir::TraitItemKind::Method(ref sig, _) => {
856 has_late_bound_regions(tcx, &item.generics, &sig.decl)
860 Node::ImplItem(item) => match item.node {
861 hir::ImplItemKind::Method(ref sig, _) => {
862 has_late_bound_regions(tcx, &item.generics, &sig.decl)
866 Node::ForeignItem(item) => match item.node {
867 hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
868 has_late_bound_regions(tcx, generics, fn_decl)
872 Node::Item(item) => match item.node {
873 hir::ItemKind::Fn(ref fn_decl, .., ref generics, _) => {
874 has_late_bound_regions(tcx, generics, fn_decl)
882 fn generics_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx ty::Generics {
885 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
887 let node = tcx.hir().get(hir_id);
888 let parent_def_id = match node {
889 Node::ImplItem(_) | Node::TraitItem(_) | Node::Variant(_) |
890 Node::Ctor(..) | Node::Field(_) => {
891 let parent_id = tcx.hir().get_parent_item(hir_id);
892 Some(tcx.hir().local_def_id_from_hir_id(parent_id))
894 Node::Expr(&hir::Expr {
895 node: hir::ExprKind::Closure(..),
897 }) => Some(tcx.closure_base_def_id(def_id)),
898 Node::Item(item) => match item.node {
899 ItemKind::Existential(hir::ExistTy { impl_trait_fn, .. }) => impl_trait_fn,
905 let mut opt_self = None;
906 let mut allow_defaults = false;
908 let no_generics = hir::Generics::empty();
909 let ast_generics = match node {
910 Node::TraitItem(item) => &item.generics,
912 Node::ImplItem(item) => &item.generics,
914 Node::Item(item) => {
916 ItemKind::Fn(.., ref generics, _) | ItemKind::Impl(_, _, _, ref generics, ..) => {
920 ItemKind::Ty(_, ref generics)
921 | ItemKind::Enum(_, ref generics)
922 | ItemKind::Struct(_, ref generics)
923 | ItemKind::Existential(hir::ExistTy { ref generics, .. })
924 | ItemKind::Union(_, ref generics) => {
925 allow_defaults = true;
929 ItemKind::Trait(_, _, ref generics, ..)
930 | ItemKind::TraitAlias(ref generics, ..) => {
931 // Add in the self type parameter.
933 // Something of a hack: use the node id for the trait, also as
934 // the node id for the Self type parameter.
935 let param_id = item.hir_id;
937 opt_self = Some(ty::GenericParamDef {
939 name: kw::SelfUpper.as_interned_str(),
940 def_id: tcx.hir().local_def_id_from_hir_id(param_id),
941 pure_wrt_drop: false,
942 kind: ty::GenericParamDefKind::Type {
944 object_lifetime_default: rl::Set1::Empty,
949 allow_defaults = true;
957 Node::ForeignItem(item) => match item.node {
958 ForeignItemKind::Static(..) => &no_generics,
959 ForeignItemKind::Fn(_, _, ref generics) => generics,
960 ForeignItemKind::Type => &no_generics,
966 let has_self = opt_self.is_some();
967 let mut parent_has_self = false;
968 let mut own_start = has_self as u32;
969 let parent_count = parent_def_id.map_or(0, |def_id| {
970 let generics = tcx.generics_of(def_id);
971 assert_eq!(has_self, false);
972 parent_has_self = generics.has_self;
973 own_start = generics.count() as u32;
974 generics.parent_count + generics.params.len()
977 let mut params: Vec<_> = opt_self.into_iter().collect();
979 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
983 .map(|(i, param)| ty::GenericParamDef {
984 name: param.name.ident().as_interned_str(),
985 index: own_start + i as u32,
986 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
987 pure_wrt_drop: param.pure_wrt_drop,
988 kind: ty::GenericParamDefKind::Lifetime,
992 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
994 // Now create the real type parameters.
995 let type_start = own_start - has_self as u32 + params.len() as u32;
1001 .filter_map(|param| {
1002 let kind = match param.kind {
1003 GenericParamKind::Type {
1008 if param.name.ident().name == kw::SelfUpper {
1011 "`Self` should not be the name of a regular parameter"
1015 if !allow_defaults && default.is_some() {
1016 if !tcx.features().default_type_parameter_fallback {
1018 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1022 "defaults for type parameters are only allowed in \
1023 `struct`, `enum`, `type`, or `trait` definitions."
1029 ty::GenericParamDefKind::Type {
1030 has_default: default.is_some(),
1031 object_lifetime_default: object_lifetime_defaults
1033 .map_or(rl::Set1::Empty, |o| o[i]),
1037 GenericParamKind::Const { .. } => {
1038 if param.name.ident().name == kw::SelfUpper {
1041 "`Self` should not be the name of a regular parameter",
1045 ty::GenericParamDefKind::Const
1050 let param_def = ty::GenericParamDef {
1051 index: type_start + i as u32,
1052 name: param.name.ident().as_interned_str(),
1053 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
1054 pure_wrt_drop: param.pure_wrt_drop,
1062 // provide junk type parameter defs - the only place that
1063 // cares about anything but the length is instantiation,
1064 // and we don't do that for closures.
1065 if let Node::Expr(&hir::Expr {
1066 node: hir::ExprKind::Closure(.., gen),
1070 let dummy_args = if gen.is_some() {
1071 &["<yield_ty>", "<return_ty>", "<witness>"][..]
1073 &["<closure_kind>", "<closure_signature>"][..]
1080 .map(|(i, &arg)| ty::GenericParamDef {
1081 index: type_start + i as u32,
1082 name: InternedString::intern(arg),
1084 pure_wrt_drop: false,
1085 kind: ty::GenericParamDefKind::Type {
1087 object_lifetime_default: rl::Set1::Empty,
1093 if let Some(upvars) = tcx.upvars(def_id) {
1094 params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
1095 ty::GenericParamDef {
1096 index: type_start + i,
1097 name: InternedString::intern("<upvar>"),
1099 pure_wrt_drop: false,
1100 kind: ty::GenericParamDefKind::Type {
1102 object_lifetime_default: rl::Set1::Empty,
1110 let param_def_id_to_index = params
1112 .map(|param| (param.def_id, param.index))
1115 tcx.arena.alloc(ty::Generics {
1116 parent: parent_def_id,
1119 param_def_id_to_index,
1120 has_self: has_self || parent_has_self,
1121 has_late_bound_regions: has_late_bound_regions(tcx, node),
1125 fn report_assoc_ty_on_inherent_impl<'tcx>(tcx: TyCtxt<'tcx>, span: Span) {
1130 "associated types are not yet supported in inherent impls (see #8995)"
1134 fn type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Ty<'tcx> {
1135 checked_type_of(tcx, def_id, true).unwrap()
1138 /// Same as [`type_of`] but returns [`Option`] instead of failing.
1140 /// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
1141 /// you'd better just call [`type_of`] directly.
1142 pub fn checked_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, fail: bool) -> Option<Ty<'tcx>> {
1145 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1146 Some(hir_id) => hir_id,
1151 bug!("invalid node");
1155 let icx = ItemCtxt::new(tcx, def_id);
1157 Some(match tcx.hir().get(hir_id) {
1158 Node::TraitItem(item) => match item.node {
1159 TraitItemKind::Method(..) => {
1160 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1161 tcx.mk_fn_def(def_id, substs)
1163 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
1164 TraitItemKind::Type(_, None) => {
1168 span_bug!(item.span, "associated type missing default");
1172 Node::ImplItem(item) => match item.node {
1173 ImplItemKind::Method(..) => {
1174 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1175 tcx.mk_fn_def(def_id, substs)
1177 ImplItemKind::Const(ref ty, _) => icx.to_ty(ty),
1178 ImplItemKind::Existential(_) => {
1180 .impl_trait_ref(tcx.hir().get_parent_did(hir_id))
1183 report_assoc_ty_on_inherent_impl(tcx, item.span);
1186 find_existential_constraints(tcx, def_id)
1188 ImplItemKind::Type(ref ty) => {
1190 .impl_trait_ref(tcx.hir().get_parent_did(hir_id))
1193 report_assoc_ty_on_inherent_impl(tcx, item.span);
1200 Node::Item(item) => {
1202 ItemKind::Static(ref t, ..)
1203 | ItemKind::Const(ref t, _)
1204 | ItemKind::Ty(ref t, _)
1205 | ItemKind::Impl(.., ref t, _) => icx.to_ty(t),
1206 ItemKind::Fn(..) => {
1207 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1208 tcx.mk_fn_def(def_id, substs)
1210 ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
1211 let def = tcx.adt_def(def_id);
1212 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1213 tcx.mk_adt(def, substs)
1215 ItemKind::Existential(hir::ExistTy {
1216 impl_trait_fn: None,
1218 }) => find_existential_constraints(tcx, def_id),
1219 // Existential types desugared from `impl Trait`.
1220 ItemKind::Existential(hir::ExistTy {
1221 impl_trait_fn: Some(owner),
1224 tcx.typeck_tables_of(owner)
1225 .concrete_existential_types
1227 .map(|opaque| opaque.concrete_type)
1228 .unwrap_or_else(|| {
1229 // This can occur if some error in the
1230 // owner fn prevented us from populating
1231 // the `concrete_existential_types` table.
1232 tcx.sess.delay_span_bug(
1235 "owner {:?} has no existential type for {:?} in its tables",
1243 | ItemKind::TraitAlias(..)
1245 | ItemKind::ForeignMod(..)
1246 | ItemKind::GlobalAsm(..)
1247 | ItemKind::ExternCrate(..)
1248 | ItemKind::Use(..) => {
1254 "compute_type_of_item: unexpected item type: {:?}",
1261 Node::ForeignItem(foreign_item) => match foreign_item.node {
1262 ForeignItemKind::Fn(..) => {
1263 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1264 tcx.mk_fn_def(def_id, substs)
1266 ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
1267 ForeignItemKind::Type => tcx.mk_foreign(def_id),
1270 Node::Ctor(&ref def) | Node::Variant(&Spanned {
1271 node: hir::VariantKind { data: ref def, .. },
1274 VariantData::Unit(..) | VariantData::Struct(..) => {
1275 tcx.type_of(tcx.hir().get_parent_did(hir_id))
1277 VariantData::Tuple(..) => {
1278 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1279 tcx.mk_fn_def(def_id, substs)
1283 Node::Field(field) => icx.to_ty(&field.ty),
1285 Node::Expr(&hir::Expr {
1286 node: hir::ExprKind::Closure(.., gen),
1290 return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
1293 let substs = ty::ClosureSubsts {
1294 substs: InternalSubsts::identity_for_item(tcx, def_id),
1297 tcx.mk_closure(def_id, substs)
1300 Node::AnonConst(_) => {
1301 let parent_node = tcx.hir().get(tcx.hir().get_parent_node_by_hir_id(hir_id));
1304 node: hir::TyKind::Array(_, ref constant),
1307 | Node::Ty(&hir::Ty {
1308 node: hir::TyKind::Typeof(ref constant),
1311 | Node::Expr(&hir::Expr {
1312 node: ExprKind::Repeat(_, ref constant),
1314 }) if constant.hir_id == hir_id =>
1319 Node::Variant(&Spanned {
1322 disr_expr: Some(ref e),
1326 }) if e.hir_id == hir_id =>
1328 tcx.adt_def(tcx.hir().get_parent_did(hir_id))
1334 Node::Ty(&hir::Ty { node: hir::TyKind::Path(_), .. }) |
1335 Node::Expr(&hir::Expr { node: ExprKind::Struct(..), .. }) |
1336 Node::Expr(&hir::Expr { node: ExprKind::Path(_), .. }) |
1337 Node::TraitRef(..) => {
1338 let path = match parent_node {
1340 node: hir::TyKind::Path(QPath::Resolved(_, ref path)),
1343 | Node::Expr(&hir::Expr {
1344 node: ExprKind::Path(QPath::Resolved(_, ref path)),
1349 Node::Expr(&hir::Expr { node: ExprKind::Struct(ref path, ..), .. }) => {
1350 if let QPath::Resolved(_, ref path) = **path {
1356 Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(path),
1360 if let Some(path) = path {
1361 let arg_index = path.segments.iter()
1362 .filter_map(|seg| seg.args.as_ref())
1363 .map(|generic_args| generic_args.args.as_ref())
1366 .filter(|arg| arg.is_const())
1368 .filter(|(_, arg)| arg.id() == hir_id)
1369 .map(|(index, _)| index)
1376 bug!("no arg matching AnonConst in path")
1380 // We've encountered an `AnonConst` in some path, so we need to
1381 // figure out which generic parameter it corresponds to and return
1382 // the relevant type.
1383 let generics = match path.res {
1384 Res::Def(DefKind::Ctor(..), def_id) => {
1385 tcx.generics_of(tcx.parent(def_id).unwrap())
1387 Res::Def(_, def_id) => tcx.generics_of(def_id),
1388 Res::Err => return Some(tcx.types.err),
1389 _ if !fail => return None,
1391 tcx.sess.delay_span_bug(
1394 "unexpected const parent path def {:?}",
1398 return Some(tcx.types.err);
1402 generics.params.iter()
1404 if let ty::GenericParamDefKind::Const = param.kind {
1411 .map(|param| tcx.type_of(param.def_id))
1412 // This is no generic parameter associated with the arg. This is
1413 // probably from an extra arg where one is not needed.
1414 .unwrap_or(tcx.types.err)
1419 tcx.sess.delay_span_bug(
1422 "unexpected const parent path {:?}",
1426 return Some(tcx.types.err);
1434 tcx.sess.delay_span_bug(
1437 "unexpected const parent in type_of_def_id(): {:?}", x
1445 Node::GenericParam(param) => match ¶m.kind {
1446 hir::GenericParamKind::Type { default: Some(ref ty), .. } |
1447 hir::GenericParamKind::Const { ref ty, .. } => {
1454 bug!("unexpected non-type Node::GenericParam: {:?}", x)
1462 bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
1467 fn find_existential_constraints<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Ty<'tcx> {
1468 use rustc::hir::{ImplItem, Item, TraitItem};
1470 debug!("find_existential_constraints({:?})", def_id);
1472 struct ConstraintLocator<'tcx> {
1475 // (first found type span, actual type, mapping from the existential type's generic
1476 // parameters to the concrete type's generic parameters)
1478 // The mapping is an index for each use site of a generic parameter in the concrete type
1480 // The indices index into the generic parameters on the existential type.
1481 found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
1484 impl ConstraintLocator<'tcx> {
1485 fn check(&mut self, def_id: DefId) {
1486 // Don't try to check items that cannot possibly constrain the type.
1487 if !self.tcx.has_typeck_tables(def_id) {
1489 "find_existential_constraints: no constraint for `{:?}` at `{:?}`: no tables",
1497 .typeck_tables_of(def_id)
1498 .concrete_existential_types
1500 if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
1502 "find_existential_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
1508 // FIXME(oli-obk): trace the actual span from inference to improve errors.
1509 let span = self.tcx.def_span(def_id);
1510 // used to quickly look up the position of a generic parameter
1511 let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
1512 // Skipping binder is ok, since we only use this to find generic parameters and
1514 for (idx, subst) in substs.iter().enumerate() {
1515 if let UnpackedKind::Type(ty) = subst.unpack() {
1516 if let ty::Param(p) = ty.sty {
1517 if index_map.insert(p, idx).is_some() {
1518 // There was already an entry for `p`, meaning a generic parameter
1520 self.tcx.sess.span_err(
1523 "defining existential type use restricts existential \
1524 type by using the generic parameter `{}` twice",
1531 self.tcx.sess.delay_span_bug(
1534 "non-defining exist ty use in defining scope: {:?}, {:?}",
1535 concrete_type, substs,
1541 // Compute the index within the existential type for each generic parameter used in
1542 // the concrete type.
1543 let indices = concrete_type
1544 .subst(self.tcx, substs)
1546 .filter_map(|t| match &t.sty {
1547 ty::Param(p) => Some(*index_map.get(p).unwrap()),
1550 let is_param = |ty: Ty<'_>| match ty.sty {
1551 ty::Param(_) => true,
1554 if !substs.types().all(is_param) {
1555 self.tcx.sess.span_err(
1557 "defining existential type use does not fully define existential type",
1559 } else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
1560 let mut ty = concrete_type.walk().fuse();
1561 let mut p_ty = prev_ty.walk().fuse();
1562 let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.sty, &p.sty) {
1563 // Type parameters are equal to any other type parameter for the purpose of
1564 // concrete type equality, as it is possible to obtain the same type just
1565 // by passing matching parameters to a function.
1566 (ty::Param(_), ty::Param(_)) => true,
1569 if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
1570 debug!("find_existential_constraints: span={:?}", span);
1571 // Found different concrete types for the existential type.
1572 let mut err = self.tcx.sess.struct_span_err(
1574 "concrete type differs from previous defining existential type use",
1578 format!("expected `{}`, got `{}`", prev_ty, concrete_type),
1580 err.span_note(prev_span, "previous use here");
1582 } else if indices != *prev_indices {
1583 // Found "same" concrete types, but the generic parameter order differs.
1584 let mut err = self.tcx.sess.struct_span_err(
1586 "concrete type's generic parameters differ from previous defining use",
1588 use std::fmt::Write;
1589 let mut s = String::new();
1590 write!(s, "expected [").unwrap();
1591 let list = |s: &mut String, indices: &Vec<usize>| {
1592 let mut indices = indices.iter().cloned();
1593 if let Some(first) = indices.next() {
1594 write!(s, "`{}`", substs[first]).unwrap();
1596 write!(s, ", `{}`", substs[i]).unwrap();
1600 list(&mut s, prev_indices);
1601 write!(s, "], got [").unwrap();
1602 list(&mut s, &indices);
1603 write!(s, "]").unwrap();
1604 err.span_label(span, s);
1605 err.span_note(prev_span, "previous use here");
1609 self.found = Some((span, concrete_type, indices));
1613 "find_existential_constraints: no constraint for `{:?}` at `{:?}`",
1621 impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
1622 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
1623 intravisit::NestedVisitorMap::All(&self.tcx.hir())
1625 fn visit_item(&mut self, it: &'tcx Item) {
1626 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1627 // The existential type itself or its children are not within its reveal scope.
1628 if def_id != self.def_id {
1630 intravisit::walk_item(self, it);
1633 fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
1634 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1635 // The existential type itself or its children are not within its reveal scope.
1636 if def_id != self.def_id {
1638 intravisit::walk_impl_item(self, it);
1641 fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
1642 let def_id = self.tcx.hir().local_def_id_from_hir_id(it.hir_id);
1644 intravisit::walk_trait_item(self, it);
1648 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1649 let scope = tcx.hir()
1650 .get_defining_scope(hir_id)
1651 .expect("could not get defining scope");
1652 let mut locator = ConstraintLocator {
1658 debug!("find_existential_constraints: scope={:?}", scope);
1660 if scope == hir::CRATE_HIR_ID {
1661 intravisit::walk_crate(&mut locator, tcx.hir().krate());
1663 debug!("find_existential_constraints: scope={:?}", tcx.hir().get(scope));
1664 match tcx.hir().get(scope) {
1665 Node::Item(ref it) => intravisit::walk_item(&mut locator, it),
1666 Node::ImplItem(ref it) => intravisit::walk_impl_item(&mut locator, it),
1667 Node::TraitItem(ref it) => intravisit::walk_trait_item(&mut locator, it),
1669 "{:?} is not a valid scope for an existential type item",
1675 match locator.found {
1676 Some((_, ty, _)) => ty,
1678 let span = tcx.def_span(def_id);
1679 tcx.sess.span_err(span, "could not find defining uses");
1685 fn fn_sig<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::PolyFnSig<'tcx> {
1687 use rustc::hir::Node::*;
1689 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1691 let icx = ItemCtxt::new(tcx, def_id);
1693 match tcx.hir().get(hir_id) {
1694 TraitItem(hir::TraitItem {
1695 node: TraitItemKind::Method(sig, _),
1698 | ImplItem(hir::ImplItem {
1699 node: ImplItemKind::Method(sig, _),
1701 }) => AstConv::ty_of_fn(&icx, sig.header.unsafety, sig.header.abi, &sig.decl),
1704 node: ItemKind::Fn(decl, header, _, _),
1706 }) => AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl),
1708 ForeignItem(&hir::ForeignItem {
1709 node: ForeignItemKind::Fn(ref fn_decl, _, _),
1712 let abi = tcx.hir().get_foreign_abi(hir_id);
1713 compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
1716 Ctor(data) | Variant(Spanned {
1717 node: hir::VariantKind { data, .. },
1719 }) if data.ctor_hir_id().is_some() => {
1720 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id));
1721 let inputs = data.fields()
1723 .map(|f| tcx.type_of(tcx.hir().local_def_id_from_hir_id(f.hir_id)));
1724 ty::Binder::bind(tcx.mk_fn_sig(
1728 hir::Unsafety::Normal,
1734 node: hir::ExprKind::Closure(..),
1737 // Closure signatures are not like other function
1738 // signatures and cannot be accessed through `fn_sig`. For
1739 // example, a closure signature excludes the `self`
1740 // argument. In any case they are embedded within the
1741 // closure type as part of the `ClosureSubsts`.
1744 // the signature of a closure, you should use the
1745 // `closure_sig` method on the `ClosureSubsts`:
1747 // closure_substs.closure_sig(def_id, tcx)
1749 // or, inside of an inference context, you can use
1751 // infcx.closure_sig(def_id, closure_substs)
1752 bug!("to get the signature of a closure, use `closure_sig()` not `fn_sig()`");
1756 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1761 fn impl_trait_ref<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Option<ty::TraitRef<'tcx>> {
1762 let icx = ItemCtxt::new(tcx, def_id);
1764 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1765 match tcx.hir().expect_item(hir_id).node {
1766 hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
1767 opt_trait_ref.as_ref().map(|ast_trait_ref| {
1768 let selfty = tcx.type_of(def_id);
1769 AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1776 fn impl_polarity<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> hir::ImplPolarity {
1777 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1778 match tcx.hir().expect_item(hir_id).node {
1779 hir::ItemKind::Impl(_, polarity, ..) => polarity,
1780 ref item => bug!("impl_polarity: {:?} not an impl", item),
1784 /// Returns the early-bound lifetimes declared in this generics
1785 /// listing. For anything other than fns/methods, this is just all
1786 /// the lifetimes that are declared. For fns or methods, we have to
1787 /// screen out those that do not appear in any where-clauses etc using
1788 /// `resolve_lifetime::early_bound_lifetimes`.
1789 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1791 generics: &'a hir::Generics,
1792 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {
1796 .filter(move |param| match param.kind {
1797 GenericParamKind::Lifetime { .. } => {
1798 !tcx.is_late_bound(param.hir_id)
1804 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1805 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1806 /// inferred constraints concerning which regions outlive other regions.
1807 fn predicates_defined_on<'tcx>(
1810 ) -> &'tcx ty::GenericPredicates<'tcx> {
1811 debug!("predicates_defined_on({:?})", def_id);
1812 let mut result = tcx.explicit_predicates_of(def_id);
1814 "predicates_defined_on: explicit_predicates_of({:?}) = {:?}",
1818 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1819 if !inferred_outlives.is_empty() {
1820 let span = tcx.def_span(def_id);
1822 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1826 let mut predicates = (*result).clone();
1827 predicates.predicates.extend(inferred_outlives.iter().map(|&p| (p, span)));
1828 result = tcx.arena.alloc(predicates);
1830 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1834 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1835 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1836 /// `Self: Trait` predicates for traits.
1837 fn predicates_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx ty::GenericPredicates<'tcx> {
1838 let mut result = tcx.predicates_defined_on(def_id);
1840 if tcx.is_trait(def_id) {
1841 // For traits, add `Self: Trait` predicate. This is
1842 // not part of the predicates that a user writes, but it
1843 // is something that one must prove in order to invoke a
1844 // method or project an associated type.
1846 // In the chalk setup, this predicate is not part of the
1847 // "predicates" for a trait item. But it is useful in
1848 // rustc because if you directly (e.g.) invoke a trait
1849 // method like `Trait::method(...)`, you must naturally
1850 // prove that the trait applies to the types that were
1851 // used, and adding the predicate into this list ensures
1852 // that this is done.
1853 let span = tcx.def_span(def_id);
1854 let mut predicates = (*result).clone();
1855 predicates.predicates.push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span));
1856 result = tcx.arena.alloc(predicates);
1858 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
1862 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
1863 /// N.B., this does not include any implied/inferred constraints.
1864 fn explicit_predicates_of<'tcx>(
1867 ) -> &'tcx ty::GenericPredicates<'tcx> {
1869 use rustc_data_structures::fx::FxHashSet;
1871 debug!("explicit_predicates_of(def_id={:?})", def_id);
1873 /// A data structure with unique elements, which preserves order of insertion.
1874 /// Preserving the order of insertion is important here so as not to break
1875 /// compile-fail UI tests.
1876 struct UniquePredicates<'tcx> {
1877 predicates: Vec<(ty::Predicate<'tcx>, Span)>,
1878 uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
1881 impl<'tcx> UniquePredicates<'tcx> {
1885 uniques: FxHashSet::default(),
1889 fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
1890 if self.uniques.insert(value) {
1891 self.predicates.push(value);
1895 fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
1902 let hir_id = match tcx.hir().as_local_hir_id(def_id) {
1903 Some(hir_id) => hir_id,
1904 None => return tcx.predicates_of(def_id),
1906 let node = tcx.hir().get(hir_id);
1908 let mut is_trait = None;
1909 let mut is_default_impl_trait = None;
1911 let icx = ItemCtxt::new(tcx, def_id);
1913 const NO_GENERICS: &hir::Generics = &hir::Generics::empty();
1915 let empty_trait_items = HirVec::new();
1917 let mut predicates = UniquePredicates::new();
1919 let ast_generics = match node {
1920 Node::TraitItem(item) => &item.generics,
1922 Node::ImplItem(item) => match item.node {
1923 ImplItemKind::Existential(ref bounds) => {
1924 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1925 let opaque_ty = tcx.mk_opaque(def_id, substs);
1927 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
1928 let bounds = AstConv::compute_bounds(
1932 SizedByDefault::Yes,
1933 tcx.def_span(def_id),
1936 predicates.extend(bounds.predicates(tcx, opaque_ty));
1939 _ => &item.generics,
1942 Node::Item(item) => {
1944 ItemKind::Impl(_, _, defaultness, ref generics, ..) => {
1945 if defaultness.is_default() {
1946 is_default_impl_trait = tcx.impl_trait_ref(def_id);
1950 ItemKind::Fn(.., ref generics, _)
1951 | ItemKind::Ty(_, ref generics)
1952 | ItemKind::Enum(_, ref generics)
1953 | ItemKind::Struct(_, ref generics)
1954 | ItemKind::Union(_, ref generics) => generics,
1956 ItemKind::Trait(_, _, ref generics, .., ref items) => {
1957 is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
1960 ItemKind::TraitAlias(ref generics, _) => {
1961 is_trait = Some((ty::TraitRef::identity(tcx, def_id), &empty_trait_items));
1964 ItemKind::Existential(ExistTy {
1970 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1971 let opaque_ty = tcx.mk_opaque(def_id, substs);
1973 // Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
1974 let bounds = AstConv::compute_bounds(
1978 SizedByDefault::Yes,
1979 tcx.def_span(def_id),
1982 let bounds_predicates = bounds.predicates(tcx, opaque_ty);
1983 if impl_trait_fn.is_some() {
1985 return tcx.arena.alloc(ty::GenericPredicates {
1987 predicates: bounds_predicates,
1990 // named existential types
1991 predicates.extend(bounds_predicates);
2000 Node::ForeignItem(item) => match item.node {
2001 ForeignItemKind::Static(..) => NO_GENERICS,
2002 ForeignItemKind::Fn(_, _, ref generics) => generics,
2003 ForeignItemKind::Type => NO_GENERICS,
2009 let generics = tcx.generics_of(def_id);
2010 let parent_count = generics.parent_count as u32;
2011 let has_own_self = generics.has_self && parent_count == 0;
2013 // Below we'll consider the bounds on the type parameters (including `Self`)
2014 // and the explicit where-clauses, but to get the full set of predicates
2015 // on a trait we need to add in the supertrait bounds and bounds found on
2016 // associated types.
2017 if let Some((_trait_ref, _)) = is_trait {
2018 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2021 // In default impls, we can assume that the self type implements
2022 // the trait. So in:
2024 // default impl Foo for Bar { .. }
2026 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2027 // (see below). Recall that a default impl is not itself an impl, but rather a
2028 // set of defaults that can be incorporated into another impl.
2029 if let Some(trait_ref) = is_default_impl_trait {
2030 predicates.push((trait_ref.to_poly_trait_ref().to_predicate(), tcx.def_span(def_id)));
2033 // Collect the region predicates that were declared inline as
2034 // well. In the case of parameters declared on a fn or method, we
2035 // have to be careful to only iterate over early-bound regions.
2036 let mut index = parent_count + has_own_self as u32;
2037 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2038 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2039 def_id: tcx.hir().local_def_id_from_hir_id(param.hir_id),
2041 name: param.name.ident().as_interned_str(),
2046 GenericParamKind::Lifetime { .. } => {
2047 param.bounds.iter().for_each(|bound| match bound {
2048 hir::GenericBound::Outlives(lt) => {
2049 let bound = AstConv::ast_region_to_region(&icx, <, None);
2050 let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
2051 predicates.push((outlives.to_predicate(), lt.span));
2060 // Collect the predicates that were written inline by the user on each
2061 // type parameter (e.g., `<T: Foo>`).
2062 for param in &ast_generics.params {
2063 if let GenericParamKind::Type { .. } = param.kind {
2064 let name = param.name.ident().as_interned_str();
2065 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2068 let sized = SizedByDefault::Yes;
2069 let bounds = AstConv::compute_bounds(&icx, param_ty, ¶m.bounds, sized, param.span);
2070 predicates.extend(bounds.predicates(tcx, param_ty));
2074 // Add in the bounds that appear in the where-clause.
2075 let where_clause = &ast_generics.where_clause;
2076 for predicate in &where_clause.predicates {
2078 &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
2079 let ty = icx.to_ty(&bound_pred.bounded_ty);
2081 // Keep the type around in a dummy predicate, in case of no bounds.
2082 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2083 // is still checked for WF.
2084 if bound_pred.bounds.is_empty() {
2085 if let ty::Param(_) = ty.sty {
2086 // This is a `where T:`, which can be in the HIR from the
2087 // transformation that moves `?Sized` to `T`'s declaration.
2088 // We can skip the predicate because type parameters are
2089 // trivially WF, but also we *should*, to avoid exposing
2090 // users who never wrote `where Type:,` themselves, to
2091 // compiler/tooling bugs from not handling WF predicates.
2093 let span = bound_pred.bounded_ty.span;
2094 let predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
2096 (ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
2101 for bound in bound_pred.bounds.iter() {
2103 &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
2104 let mut bounds = Bounds::default();
2106 let (trait_ref, _) = AstConv::instantiate_poly_trait_ref(
2113 predicates.push((trait_ref.to_predicate(), poly_trait_ref.span));
2114 predicates.extend(bounds.predicates(tcx, ty));
2117 &hir::GenericBound::Outlives(ref lifetime) => {
2118 let region = AstConv::ast_region_to_region(&icx, lifetime, None);
2119 let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
2120 predicates.push((ty::Predicate::TypeOutlives(pred), lifetime.span))
2126 &hir::WherePredicate::RegionPredicate(ref region_pred) => {
2127 let r1 = AstConv::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2128 predicates.extend(region_pred.bounds.iter().map(|bound| {
2129 let (r2, span) = match bound {
2130 hir::GenericBound::Outlives(lt) => {
2131 (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
2135 let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
2137 (ty::Predicate::RegionOutlives(pred), span)
2141 &hir::WherePredicate::EqPredicate(..) => {
2147 // Add predicates from associated type bounds.
2148 if let Some((self_trait_ref, trait_items)) = is_trait {
2149 predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
2150 let trait_item = tcx.hir().trait_item(trait_item_ref.id);
2151 let bounds = match trait_item.node {
2152 hir::TraitItemKind::Type(ref bounds, _) => bounds,
2153 _ => return Vec::new().into_iter()
2157 tcx.mk_projection(tcx.hir().local_def_id_from_hir_id(trait_item.hir_id),
2158 self_trait_ref.substs);
2160 let bounds = AstConv::compute_bounds(
2161 &ItemCtxt::new(tcx, def_id),
2164 SizedByDefault::Yes,
2168 bounds.predicates(tcx, assoc_ty).into_iter()
2172 let mut predicates = predicates.predicates;
2174 // Subtle: before we store the predicates into the tcx, we
2175 // sort them so that predicates like `T: Foo<Item=U>` come
2176 // before uses of `U`. This avoids false ambiguity errors
2177 // in trait checking. See `setup_constraining_predicates`
2179 if let Node::Item(&Item {
2180 node: ItemKind::Impl(..),
2184 let self_ty = tcx.type_of(def_id);
2185 let trait_ref = tcx.impl_trait_ref(def_id);
2186 cgp::setup_constraining_predicates(
2190 &mut cgp::parameters_for_impl(self_ty, trait_ref),
2194 let result = tcx.arena.alloc(ty::GenericPredicates {
2195 parent: generics.parent,
2198 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2202 /// Converts a specific `GenericBound` from the AST into a set of
2203 /// predicates that apply to the self type. A vector is returned
2204 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2205 /// predicates) to one (`T: Foo`) to many (`T: Bar<X=i32>` adds `T: Bar`
2206 /// and `<T as Bar>::X == i32`).
2207 fn predicates_from_bound<'tcx>(
2208 astconv: &dyn AstConv<'tcx>,
2210 bound: &'tcx hir::GenericBound,
2211 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2213 hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
2214 let mut bounds = Bounds::default();
2215 let (pred, _) = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut bounds);
2216 iter::once((pred.to_predicate(), tr.span))
2217 .chain(bounds.predicates(astconv.tcx(), param_ty))
2220 hir::GenericBound::Outlives(ref lifetime) => {
2221 let region = astconv.ast_region_to_region(lifetime, None);
2222 let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
2223 vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
2225 hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
2229 fn compute_sig_of_foreign_fn_decl<'tcx>(
2232 decl: &'tcx hir::FnDecl,
2234 ) -> ty::PolyFnSig<'tcx> {
2235 let unsafety = if abi == abi::Abi::RustIntrinsic {
2236 intrisic_operation_unsafety(&*tcx.item_name(def_id).as_str())
2238 hir::Unsafety::Unsafe
2240 let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
2242 // Feature gate SIMD types in FFI, since I am not sure that the
2243 // ABIs are handled at all correctly. -huonw
2244 if abi != abi::Abi::RustIntrinsic
2245 && abi != abi::Abi::PlatformIntrinsic
2246 && !tcx.features().simd_ffi
2248 let check = |ast_ty: &hir::Ty, ty: Ty<'_>| {
2254 "use of SIMD type `{}` in FFI is highly experimental and \
2255 may result in invalid code",
2256 tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
2259 .help("add #![feature(simd_ffi)] to the crate attributes to enable")
2263 for (input, ty) in decl.inputs.iter().zip(*fty.inputs().skip_binder()) {
2266 if let hir::Return(ref ty) = decl.output {
2267 check(&ty, *fty.output().skip_binder())
2274 fn is_foreign_item<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool {
2275 match tcx.hir().get_if_local(def_id) {
2276 Some(Node::ForeignItem(..)) => true,
2278 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2282 fn static_mutability<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Option<hir::Mutability> {
2283 match tcx.hir().get_if_local(def_id) {
2284 Some(Node::Item(&hir::Item {
2285 node: hir::ItemKind::Static(_, mutbl, _), ..
2287 Some(Node::ForeignItem( &hir::ForeignItem {
2288 node: hir::ForeignItemKind::Static(_, mutbl), ..
2291 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2295 fn from_target_feature(
2298 attr: &ast::Attribute,
2299 whitelist: &FxHashMap<String, Option<Symbol>>,
2300 target_features: &mut Vec<Symbol>,
2302 let list = match attr.meta_item_list() {
2306 let bad_item = |span| {
2307 let msg = "malformed `target_feature` attribute input";
2308 let code = "enable = \"..\"".to_owned();
2309 tcx.sess.struct_span_err(span, &msg)
2310 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2313 let rust_features = tcx.features();
2315 // Only `enable = ...` is accepted in the meta-item list.
2316 if !item.check_name(sym::enable) {
2317 bad_item(item.span());
2321 // Must be of the form `enable = "..."` (a string).
2322 let value = match item.value_str() {
2323 Some(value) => value,
2325 bad_item(item.span());
2330 // We allow comma separation to enable multiple features.
2331 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2332 // Only allow whitelisted features per platform.
2333 let feature_gate = match whitelist.get(feature) {
2337 "the feature named `{}` is not valid for this target",
2340 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2343 format!("`{}` is not valid for this target", feature),
2345 if feature.starts_with("+") {
2346 let valid = whitelist.contains_key(&feature[1..]);
2348 err.help("consider removing the leading `+` in the feature name");
2356 // Only allow features whose feature gates have been enabled.
2357 let allowed = match feature_gate.as_ref().map(|s| *s) {
2358 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2359 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2360 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2361 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2362 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2363 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2364 Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
2365 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2366 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2367 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2368 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2369 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2370 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2371 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2372 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2373 Some(name) => bug!("unknown target feature gate {}", name),
2376 if !allowed && id.is_local() {
2377 feature_gate::emit_feature_err(
2378 &tcx.sess.parse_sess,
2379 feature_gate.unwrap(),
2381 feature_gate::GateIssue::Language,
2382 &format!("the target feature `{}` is currently unstable", feature),
2385 Some(Symbol::intern(feature))
2390 fn linkage_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Linkage {
2391 use rustc::mir::mono::Linkage::*;
2393 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2394 // applicable to variable declarations and may not really make sense for
2395 // Rust code in the first place but whitelist them anyway and trust that
2396 // the user knows what s/he's doing. Who knows, unanticipated use cases
2397 // may pop up in the future.
2399 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2400 // and don't have to be, LLVM treats them as no-ops.
2402 "appending" => Appending,
2403 "available_externally" => AvailableExternally,
2405 "extern_weak" => ExternalWeak,
2406 "external" => External,
2407 "internal" => Internal,
2408 "linkonce" => LinkOnceAny,
2409 "linkonce_odr" => LinkOnceODR,
2410 "private" => Private,
2412 "weak_odr" => WeakODR,
2414 let span = tcx.hir().span_if_local(def_id);
2415 if let Some(span) = span {
2416 tcx.sess.span_fatal(span, "invalid linkage specified")
2419 .fatal(&format!("invalid linkage specified: {}", name))
2425 fn codegen_fn_attrs<'tcx>(tcx: TyCtxt<'tcx>, id: DefId) -> CodegenFnAttrs {
2426 let attrs = tcx.get_attrs(id);
2428 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2430 let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
2432 let mut inline_span = None;
2433 for attr in attrs.iter() {
2434 if attr.check_name(sym::cold) {
2435 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2436 } else if attr.check_name(sym::rustc_allocator) {
2437 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2438 } else if attr.check_name(sym::unwind) {
2439 codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
2440 } else if attr.check_name(sym::ffi_returns_twice) {
2441 if tcx.is_foreign_item(id) {
2442 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2444 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2449 "`#[ffi_returns_twice]` may only be used on foreign functions"
2452 } else if attr.check_name(sym::rustc_allocator_nounwind) {
2453 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
2454 } else if attr.check_name(sym::naked) {
2455 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2456 } else if attr.check_name(sym::no_mangle) {
2457 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2458 } else if attr.check_name(sym::rustc_std_internal_symbol) {
2459 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2460 } else if attr.check_name(sym::no_debug) {
2461 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
2462 } else if attr.check_name(sym::used) {
2463 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2464 } else if attr.check_name(sym::thread_local) {
2465 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2466 } else if attr.check_name(sym::export_name) {
2467 if let Some(s) = attr.value_str() {
2468 if s.as_str().contains("\0") {
2469 // `#[export_name = ...]` will be converted to a null-terminated string,
2470 // so it may not contain any null characters.
2475 "`export_name` may not contain null characters"
2478 codegen_fn_attrs.export_name = Some(s);
2480 } else if attr.check_name(sym::target_feature) {
2481 if tcx.fn_sig(id).unsafety() == Unsafety::Normal {
2482 let msg = "#[target_feature(..)] can only be applied to `unsafe` functions";
2483 tcx.sess.struct_span_err(attr.span, msg)
2484 .span_label(attr.span, "can only be applied to `unsafe` functions")
2485 .span_label(tcx.def_span(id), "not an `unsafe` function")
2488 from_target_feature(
2493 &mut codegen_fn_attrs.target_features,
2495 } else if attr.check_name(sym::linkage) {
2496 if let Some(val) = attr.value_str() {
2497 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2499 } else if attr.check_name(sym::link_section) {
2500 if let Some(val) = attr.value_str() {
2501 if val.as_str().bytes().any(|b| b == 0) {
2503 "illegal null byte in link_section \
2507 tcx.sess.span_err(attr.span, &msg);
2509 codegen_fn_attrs.link_section = Some(val);
2512 } else if attr.check_name(sym::link_name) {
2513 codegen_fn_attrs.link_name = attr.value_str();
2517 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2518 if attr.path != sym::inline {
2521 match attr.meta().map(|i| i.node) {
2522 Some(MetaItemKind::Word) => {
2526 Some(MetaItemKind::List(ref items)) => {
2528 inline_span = Some(attr.span);
2529 if items.len() != 1 {
2531 tcx.sess.diagnostic(),
2534 "expected one argument"
2537 } else if list_contains_name(&items[..], sym::always) {
2539 } else if list_contains_name(&items[..], sym::never) {
2543 tcx.sess.diagnostic(),
2552 Some(MetaItemKind::NameValue(_)) => ia,
2557 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
2558 if attr.path != sym::optimize {
2561 let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
2562 match attr.meta().map(|i| i.node) {
2563 Some(MetaItemKind::Word) => {
2564 err(attr.span, "expected one argument");
2567 Some(MetaItemKind::List(ref items)) => {
2569 inline_span = Some(attr.span);
2570 if items.len() != 1 {
2571 err(attr.span, "expected one argument");
2573 } else if list_contains_name(&items[..], sym::size) {
2575 } else if list_contains_name(&items[..], sym::speed) {
2578 err(items[0].span(), "invalid argument");
2582 Some(MetaItemKind::NameValue(_)) => ia,
2587 // If a function uses #[target_feature] it can't be inlined into general
2588 // purpose functions as they wouldn't have the right target features
2589 // enabled. For that reason we also forbid #[inline(always)] as it can't be
2591 if codegen_fn_attrs.target_features.len() > 0 {
2592 if codegen_fn_attrs.inline == InlineAttr::Always {
2593 if let Some(span) = inline_span {
2596 "cannot use #[inline(always)] with \
2603 // Weak lang items have the same semantics as "std internal" symbols in the
2604 // sense that they're preserved through all our LTO passes and only
2605 // strippable by the linker.
2607 // Additionally weak lang items have predetermined symbol names.
2608 if tcx.is_weak_lang_item(id) {
2609 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2611 if let Some(name) = weak_lang_items::link_name(&attrs) {
2612 codegen_fn_attrs.export_name = Some(name);
2613 codegen_fn_attrs.link_name = Some(name);
2616 // Internal symbols to the standard library all have no_mangle semantics in
2617 // that they have defined symbol names present in the function name. This
2618 // also applies to weak symbols where they all have known symbol names.
2619 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
2620 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;