1 use rustc::hir::map as hir_map;
2 use rustc::session::CrateDisambiguator;
3 use rustc::traits::{self};
4 use rustc::ty::subst::Subst;
5 use rustc::ty::{self, ToPredicate, Ty, TyCtxt, WithConstness};
6 use rustc_data_structures::svh::Svh;
8 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
9 use rustc_span::symbol::Symbol;
12 fn sized_constraint_for_ty(tcx: TyCtxt<'tcx>, adtdef: &ty::AdtDef, ty: Ty<'tcx>) -> Vec<Ty<'tcx>> {
15 let result = match ty.kind {
16 Bool | Char | Int(..) | Uint(..) | Float(..) | RawPtr(..) | Ref(..) | FnDef(..)
17 | FnPtr(_) | Array(..) | Closure(..) | Generator(..) | Never => vec![],
19 Str | Dynamic(..) | Slice(_) | Foreign(..) | Error | GeneratorWitness(..) => {
20 // these are never sized - return the target type
24 Tuple(ref tys) => match tys.last() {
26 Some(ty) => sized_constraint_for_ty(tcx, adtdef, ty.expect_ty()),
31 let adt_tys = adt.sized_constraint(tcx);
32 debug!("sized_constraint_for_ty({:?}) intermediate = {:?}", ty, adt_tys);
35 .map(|ty| ty.subst(tcx, substs))
36 .flat_map(|ty| sized_constraint_for_ty(tcx, adtdef, ty))
40 Projection(..) | Opaque(..) => {
41 // must calculate explicitly.
42 // FIXME: consider special-casing always-Sized projections
46 UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
49 // perf hack: if there is a `T: Sized` bound, then
50 // we know that `T` is Sized and do not need to check
53 let sized_trait = match tcx.lang_items().sized_trait() {
57 let sized_predicate = ty::Binder::dummy(ty::TraitRef {
59 substs: tcx.mk_substs_trait(ty, &[]),
63 let predicates = tcx.predicates_of(adtdef.did).predicates;
64 if predicates.iter().any(|(p, _)| *p == sized_predicate) { vec![] } else { vec![ty] }
67 Placeholder(..) | Bound(..) | Infer(..) => {
68 bug!("unexpected type `{:?}` in sized_constraint_for_ty", ty)
71 debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result);
75 fn associated_item_from_trait_item_ref(
78 parent_vis: &hir::Visibility<'_>,
79 trait_item_ref: &hir::TraitItemRef,
81 let def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
82 let (kind, has_self) = match trait_item_ref.kind {
83 hir::AssocItemKind::Const => (ty::AssocKind::Const, false),
84 hir::AssocItemKind::Method { has_self } => (ty::AssocKind::Method, has_self),
85 hir::AssocItemKind::Type => (ty::AssocKind::Type, false),
86 hir::AssocItemKind::OpaqueTy => bug!("only impls can have opaque types"),
90 ident: trait_item_ref.ident,
92 // Visibility of trait items is inherited from their traits.
93 vis: ty::Visibility::from_hir(parent_vis, trait_item_ref.id.hir_id, tcx),
94 defaultness: trait_item_ref.defaultness,
96 container: ty::TraitContainer(parent_def_id),
97 method_has_self_argument: has_self,
101 fn associated_item_from_impl_item_ref(
103 parent_def_id: DefId,
104 impl_item_ref: &hir::ImplItemRef<'_>,
106 let def_id = tcx.hir().local_def_id(impl_item_ref.id.hir_id);
107 let (kind, has_self) = match impl_item_ref.kind {
108 hir::AssocItemKind::Const => (ty::AssocKind::Const, false),
109 hir::AssocItemKind::Method { has_self } => (ty::AssocKind::Method, has_self),
110 hir::AssocItemKind::Type => (ty::AssocKind::Type, false),
111 hir::AssocItemKind::OpaqueTy => (ty::AssocKind::OpaqueTy, false),
115 ident: impl_item_ref.ident,
117 // Visibility of trait impl items doesn't matter.
118 vis: ty::Visibility::from_hir(&impl_item_ref.vis, impl_item_ref.id.hir_id, tcx),
119 defaultness: impl_item_ref.defaultness,
121 container: ty::ImplContainer(parent_def_id),
122 method_has_self_argument: has_self,
126 fn associated_item(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AssocItem {
127 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
128 let parent_id = tcx.hir().get_parent_item(id);
129 let parent_def_id = tcx.hir().local_def_id(parent_id);
130 let parent_item = tcx.hir().expect_item(parent_id);
131 match parent_item.kind {
132 hir::ItemKind::Impl { ref items, .. } => {
133 if let Some(impl_item_ref) = items.iter().find(|i| i.id.hir_id == id) {
135 associated_item_from_impl_item_ref(tcx, parent_def_id, impl_item_ref);
136 debug_assert_eq!(assoc_item.def_id, def_id);
141 hir::ItemKind::Trait(.., ref trait_item_refs) => {
142 if let Some(trait_item_ref) = trait_item_refs.iter().find(|i| i.id.hir_id == id) {
143 let assoc_item = associated_item_from_trait_item_ref(
149 debug_assert_eq!(assoc_item.def_id, def_id);
159 "unexpected parent of trait or impl item or item not found: {:?}",
164 /// Calculates the `Sized` constraint.
166 /// In fact, there are only a few options for the types in the constraint:
167 /// - an obviously-unsized type
168 /// - a type parameter or projection whose Sizedness can't be known
169 /// - a tuple of type parameters or projections, if there are multiple
171 /// - a Error, if a type contained itself. The representability
172 /// check should catch this case.
173 fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AdtSizedConstraint<'_> {
174 let def = tcx.adt_def(def_id);
176 let result = tcx.mk_type_list(
179 .flat_map(|v| v.fields.last())
180 .flat_map(|f| sized_constraint_for_ty(tcx, def, tcx.type_of(f.did))),
183 debug!("adt_sized_constraint: {:?} => {:?}", def, result);
185 ty::AdtSizedConstraint(result)
188 fn associated_item_def_ids(tcx: TyCtxt<'_>, def_id: DefId) -> &[DefId] {
189 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
190 let item = tcx.hir().expect_item(id);
192 hir::ItemKind::Trait(.., ref trait_item_refs) => tcx.arena.alloc_from_iter(
195 .map(|trait_item_ref| trait_item_ref.id)
196 .map(|id| tcx.hir().local_def_id(id.hir_id)),
198 hir::ItemKind::Impl { ref items, .. } => tcx.arena.alloc_from_iter(
201 .map(|impl_item_ref| impl_item_ref.id)
202 .map(|id| tcx.hir().local_def_id(id.hir_id)),
204 hir::ItemKind::TraitAlias(..) => &[],
205 _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait"),
209 fn associated_items<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AssocItemsIterator<'tcx> {
210 ty::AssocItemsIterator {
211 items: tcx.arena.alloc_from_iter(
212 tcx.associated_item_def_ids(def_id).iter().map(|did| tcx.associated_item(*did)),
217 fn def_span(tcx: TyCtxt<'_>, def_id: DefId) -> Span {
218 tcx.hir().span_if_local(def_id).unwrap()
221 /// If the given `DefId` describes an item belonging to a trait,
222 /// returns the `DefId` of the trait that the trait item belongs to;
223 /// otherwise, returns `None`.
224 fn trait_of_item(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
225 tcx.opt_associated_item(def_id).and_then(|associated_item| match associated_item.container {
226 ty::TraitContainer(def_id) => Some(def_id),
227 ty::ImplContainer(_) => None,
231 /// See `ParamEnv` struct definition for details.
232 fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
233 // The param_env of an impl Trait type is its defining function's param_env
234 if let Some(parent) = ty::is_impl_trait_defn(tcx, def_id) {
235 return param_env(tcx, parent);
237 // Compute the bounds on Self and the type parameters.
239 let ty::InstantiatedPredicates { predicates, .. } =
240 tcx.predicates_of(def_id).instantiate_identity(tcx);
242 // Finally, we have to normalize the bounds in the environment, in
243 // case they contain any associated type projections. This process
244 // can yield errors if the put in illegal associated types, like
245 // `<i32 as Foo>::Bar` where `i32` does not implement `Foo`. We
246 // report these errors right here; this doesn't actually feel
247 // right to me, because constructing the environment feels like a
248 // kind of a "idempotent" action, but I'm not sure where would be
249 // a better place. In practice, we construct environments for
250 // every fn once during type checking, and we'll abort if there
251 // are any errors at that point, so after type checking you can be
252 // sure that this will succeed without errors anyway.
254 let unnormalized_env = ty::ParamEnv::new(
255 tcx.intern_predicates(&predicates),
256 traits::Reveal::UserFacing,
257 tcx.sess.opts.debugging_opts.chalk.then_some(def_id),
260 let body_id = tcx.hir().as_local_hir_id(def_id).map_or(hir::DUMMY_HIR_ID, |id| {
261 tcx.hir().maybe_body_owned_by(id).map_or(id, |body| body.hir_id)
263 let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id);
264 traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause)
267 fn crate_disambiguator(tcx: TyCtxt<'_>, crate_num: CrateNum) -> CrateDisambiguator {
268 assert_eq!(crate_num, LOCAL_CRATE);
269 tcx.sess.local_crate_disambiguator()
272 fn original_crate_name(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Symbol {
273 assert_eq!(crate_num, LOCAL_CRATE);
277 fn crate_hash(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Svh {
278 assert_eq!(crate_num, LOCAL_CRATE);
282 fn instance_def_size_estimate<'tcx>(
284 instance_def: ty::InstanceDef<'tcx>,
289 InstanceDef::Item(..) | InstanceDef::DropGlue(..) => {
290 let mir = tcx.instance_mir(instance_def);
291 mir.basic_blocks().iter().map(|bb| bb.statements.len()).sum()
293 // Estimate the size of other compiler-generated shims to be 1.
298 /// If `def_id` is an issue 33140 hack impl, returns its self type; otherwise, returns `None`.
300 /// See [`ImplOverlapKind::Issue33140`] for more details.
301 fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Ty<'_>> {
302 debug!("issue33140_self_ty({:?})", def_id);
305 .impl_trait_ref(def_id)
306 .unwrap_or_else(|| bug!("issue33140_self_ty called on inherent impl {:?}", def_id));
308 debug!("issue33140_self_ty({:?}), trait-ref={:?}", def_id, trait_ref);
310 let is_marker_like = tcx.impl_polarity(def_id) == ty::ImplPolarity::Positive
311 && tcx.associated_item_def_ids(trait_ref.def_id).is_empty();
313 // Check whether these impls would be ok for a marker trait.
315 debug!("issue33140_self_ty - not marker-like!");
319 // impl must be `impl Trait for dyn Marker1 + Marker2 + ...`
320 if trait_ref.substs.len() != 1 {
321 debug!("issue33140_self_ty - impl has substs!");
325 let predicates = tcx.predicates_of(def_id);
326 if predicates.parent.is_some() || !predicates.predicates.is_empty() {
327 debug!("issue33140_self_ty - impl has predicates {:?}!", predicates);
331 let self_ty = trait_ref.self_ty();
332 let self_ty_matches = match self_ty.kind {
333 ty::Dynamic(ref data, ty::ReStatic) => data.principal().is_none(),
338 debug!("issue33140_self_ty - MATCHES!");
341 debug!("issue33140_self_ty - non-matching self type");
346 /// Check if a function is async.
347 fn asyncness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::IsAsync {
350 .as_local_hir_id(def_id)
351 .unwrap_or_else(|| bug!("asyncness: expected local `DefId`, got `{:?}`", def_id));
353 let node = tcx.hir().get(hir_id);
355 let fn_like = hir_map::blocks::FnLikeNode::from_node(node).unwrap_or_else(|| {
356 bug!("asyncness: expected fn-like node but got `{:?}`", def_id);
362 pub fn provide(providers: &mut ty::query::Providers<'_>) {
363 *providers = ty::query::Providers {
366 associated_item_def_ids,
368 adt_sized_constraint,
375 instance_def_size_estimate,