| use rustc_data_structures::fx::FxIndexSet; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::DefId; |
| use rustc_middle::ty::subst::Subst; |
| use rustc_middle::ty::{self, Binder, Predicate, PredicateKind, ToPredicate, Ty, TyCtxt}; |
| use rustc_span::{sym, Span}; |
| use rustc_trait_selection::traits; |
| |
| fn sized_constraint_for_ty<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| adtdef: ty::AdtDef<'tcx>, |
| ty: Ty<'tcx>, |
| ) -> Vec<Ty<'tcx>> { |
| use ty::TyKind::*; |
| |
| let result = match ty.kind() { |
| Bool | Char | Int(..) | Uint(..) | Float(..) | RawPtr(..) | Ref(..) | FnDef(..) |
| | FnPtr(_) | Array(..) | Closure(..) | Generator(..) | Never => vec![], |
| |
| Str | Dynamic(..) | Slice(_) | Foreign(..) | Error(_) | GeneratorWitness(..) => { |
| // these are never sized - return the target type |
| vec![ty] |
| } |
| |
| Tuple(ref tys) => match tys.last() { |
| None => vec![], |
| Some(&ty) => sized_constraint_for_ty(tcx, adtdef, ty), |
| }, |
| |
| Adt(adt, substs) => { |
| // recursive case |
| let adt_tys = adt.sized_constraint(tcx); |
| debug!("sized_constraint_for_ty({:?}) intermediate = {:?}", ty, adt_tys); |
| adt_tys |
| .iter() |
| .map(|ty| ty.subst(tcx, substs)) |
| .flat_map(|ty| sized_constraint_for_ty(tcx, adtdef, ty)) |
| .collect() |
| } |
| |
| Projection(..) | Opaque(..) => { |
| // must calculate explicitly. |
| // FIXME: consider special-casing always-Sized projections |
| vec![ty] |
| } |
| |
| Param(..) => { |
| // perf hack: if there is a `T: Sized` bound, then |
| // we know that `T` is Sized and do not need to check |
| // it on the impl. |
| |
| let Some(sized_trait) = tcx.lang_items().sized_trait() else { return vec![ty] }; |
| let sized_predicate = ty::Binder::dummy(ty::TraitRef { |
| def_id: sized_trait, |
| substs: tcx.mk_substs_trait(ty, &[]), |
| }) |
| .without_const() |
| .to_predicate(tcx); |
| let predicates = tcx.predicates_of(adtdef.did()).predicates; |
| if predicates.iter().any(|(p, _)| *p == sized_predicate) { vec![] } else { vec![ty] } |
| } |
| |
| Placeholder(..) | Bound(..) | Infer(..) => { |
| bug!("unexpected type `{:?}` in sized_constraint_for_ty", ty) |
| } |
| }; |
| debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result); |
| result |
| } |
| |
| fn impl_defaultness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Defaultness { |
| let item = tcx.hir().expect_item(def_id.expect_local()); |
| if let hir::ItemKind::Impl(impl_) = &item.kind { |
| impl_.defaultness |
| } else { |
| bug!("`impl_defaultness` called on {:?}", item); |
| } |
| } |
| |
| /// Calculates the `Sized` constraint. |
| /// |
| /// In fact, there are only a few options for the types in the constraint: |
| /// - an obviously-unsized type |
| /// - a type parameter or projection whose Sizedness can't be known |
| /// - a tuple of type parameters or projections, if there are multiple |
| /// such. |
| /// - an Error, if a type contained itself. The representability |
| /// check should catch this case. |
| fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AdtSizedConstraint<'_> { |
| let def = tcx.adt_def(def_id); |
| |
| let result = tcx.mk_type_list( |
| def.variants() |
| .iter() |
| .flat_map(|v| v.fields.last()) |
| .flat_map(|f| sized_constraint_for_ty(tcx, def, tcx.type_of(f.did))), |
| ); |
| |
| debug!("adt_sized_constraint: {:?} => {:?}", def, result); |
| |
| ty::AdtSizedConstraint(result) |
| } |
| |
| fn def_ident_span(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Span> { |
| tcx.hir() |
| .get_if_local(def_id) |
| .and_then(|node| match node { |
| // A `Ctor` doesn't have an identifier itself, but its parent |
| // struct/variant does. Compare with `hir::Map::opt_span`. |
| hir::Node::Ctor(ctor) => ctor |
| .ctor_hir_id() |
| .and_then(|ctor_id| tcx.hir().find(tcx.hir().get_parent_node(ctor_id))) |
| .and_then(|parent| parent.ident()), |
| _ => node.ident(), |
| }) |
| .map(|ident| ident.span) |
| } |
| |
| /// See `ParamEnv` struct definition for details. |
| #[instrument(level = "debug", skip(tcx))] |
| fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> { |
| // The param_env of an impl Trait type is its defining function's param_env |
| if let Some(parent) = ty::is_impl_trait_defn(tcx, def_id) { |
| return param_env(tcx, parent.to_def_id()); |
| } |
| // Compute the bounds on Self and the type parameters. |
| |
| let ty::InstantiatedPredicates { mut predicates, .. } = |
| tcx.predicates_of(def_id).instantiate_identity(tcx); |
| |
| // Finally, we have to normalize the bounds in the environment, in |
| // case they contain any associated type projections. This process |
| // can yield errors if the put in illegal associated types, like |
| // `<i32 as Foo>::Bar` where `i32` does not implement `Foo`. We |
| // report these errors right here; this doesn't actually feel |
| // right to me, because constructing the environment feels like a |
| // kind of an "idempotent" action, but I'm not sure where would be |
| // a better place. In practice, we construct environments for |
| // every fn once during type checking, and we'll abort if there |
| // are any errors at that point, so outside of type inference you can be |
| // sure that this will succeed without errors anyway. |
| |
| if tcx.sess.opts.debugging_opts.chalk { |
| let environment = well_formed_types_in_env(tcx, def_id); |
| predicates.extend(environment); |
| } |
| |
| let local_did = def_id.as_local(); |
| let hir_id = local_did.map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id)); |
| |
| let constness = match hir_id { |
| Some(hir_id) => match tcx.hir().get(hir_id) { |
| hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. }) |
| if tcx.has_attr(def_id, sym::default_method_body_is_const) => |
| { |
| hir::Constness::Const |
| } |
| |
| hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(..), .. }) |
| | hir::Node::Item(hir::Item { kind: hir::ItemKind::Static(..), .. }) |
| | hir::Node::TraitItem(hir::TraitItem { |
| kind: hir::TraitItemKind::Const(..), .. |
| }) |
| | hir::Node::AnonConst(_) |
| | hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. }) |
| | hir::Node::ImplItem(hir::ImplItem { |
| kind: |
| hir::ImplItemKind::Fn( |
| hir::FnSig { |
| header: hir::FnHeader { constness: hir::Constness::Const, .. }, |
| .. |
| }, |
| .., |
| ), |
| .. |
| }) => hir::Constness::Const, |
| |
| hir::Node::ImplItem(hir::ImplItem { |
| kind: hir::ImplItemKind::TyAlias(..) | hir::ImplItemKind::Fn(..), |
| .. |
| }) => { |
| let parent_hir_id = tcx.hir().get_parent_node(hir_id); |
| match tcx.hir().get(parent_hir_id) { |
| hir::Node::Item(hir::Item { |
| kind: hir::ItemKind::Impl(hir::Impl { constness, .. }), |
| .. |
| }) => *constness, |
| _ => span_bug!( |
| tcx.def_span(parent_hir_id.owner), |
| "impl item's parent node is not an impl", |
| ), |
| } |
| } |
| |
| hir::Node::Item(hir::Item { |
| kind: |
| hir::ItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..), |
| .. |
| }) |
| | hir::Node::TraitItem(hir::TraitItem { |
| kind: |
| hir::TraitItemKind::Fn( |
| hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, |
| .., |
| ), |
| .. |
| }) |
| | hir::Node::Item(hir::Item { |
| kind: hir::ItemKind::Impl(hir::Impl { constness, .. }), |
| .. |
| }) => *constness, |
| |
| _ => hir::Constness::NotConst, |
| }, |
| None => hir::Constness::NotConst, |
| }; |
| |
| let unnormalized_env = ty::ParamEnv::new( |
| tcx.intern_predicates(&predicates), |
| traits::Reveal::UserFacing, |
| constness, |
| ); |
| |
| let body_id = hir_id.map_or(hir::CRATE_HIR_ID, |id| { |
| tcx.hir().maybe_body_owned_by(id).map_or(id, |body| body.hir_id) |
| }); |
| let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id); |
| traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause) |
| } |
| |
| /// Elaborate the environment. |
| /// |
| /// Collect a list of `Predicate`'s used for building the `ParamEnv`. Adds `TypeWellFormedFromEnv`'s |
| /// that are assumed to be well-formed (because they come from the environment). |
| /// |
| /// Used only in chalk mode. |
| fn well_formed_types_in_env<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| def_id: DefId, |
| ) -> &'tcx ty::List<Predicate<'tcx>> { |
| use rustc_hir::{ForeignItemKind, ImplItemKind, ItemKind, Node, TraitItemKind}; |
| use rustc_middle::ty::subst::GenericArgKind; |
| |
| debug!("environment(def_id = {:?})", def_id); |
| |
| // The environment of an impl Trait type is its defining function's environment. |
| if let Some(parent) = ty::is_impl_trait_defn(tcx, def_id) { |
| return well_formed_types_in_env(tcx, parent.to_def_id()); |
| } |
| |
| // Compute the bounds on `Self` and the type parameters. |
| let ty::InstantiatedPredicates { predicates, .. } = |
| tcx.predicates_of(def_id).instantiate_identity(tcx); |
| |
| let clauses = predicates.into_iter(); |
| |
| if !def_id.is_local() { |
| return ty::List::empty(); |
| } |
| let node = tcx.hir().get_by_def_id(def_id.expect_local()); |
| |
| enum NodeKind { |
| TraitImpl, |
| InherentImpl, |
| Fn, |
| Other, |
| } |
| |
| let node_kind = match node { |
| Node::TraitItem(item) => match item.kind { |
| TraitItemKind::Fn(..) => NodeKind::Fn, |
| _ => NodeKind::Other, |
| }, |
| |
| Node::ImplItem(item) => match item.kind { |
| ImplItemKind::Fn(..) => NodeKind::Fn, |
| _ => NodeKind::Other, |
| }, |
| |
| Node::Item(item) => match item.kind { |
| ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => NodeKind::TraitImpl, |
| ItemKind::Impl(hir::Impl { of_trait: None, .. }) => NodeKind::InherentImpl, |
| ItemKind::Fn(..) => NodeKind::Fn, |
| _ => NodeKind::Other, |
| }, |
| |
| Node::ForeignItem(item) => match item.kind { |
| ForeignItemKind::Fn(..) => NodeKind::Fn, |
| _ => NodeKind::Other, |
| }, |
| |
| // FIXME: closures? |
| _ => NodeKind::Other, |
| }; |
| |
| // FIXME(eddyb) isn't the unordered nature of this a hazard? |
| let mut inputs = FxIndexSet::default(); |
| |
| match node_kind { |
| // In a trait impl, we assume that the header trait ref and all its |
| // constituents are well-formed. |
| NodeKind::TraitImpl => { |
| let trait_ref = tcx.impl_trait_ref(def_id).expect("not an impl"); |
| |
| // FIXME(chalk): this has problems because of late-bound regions |
| //inputs.extend(trait_ref.substs.iter().flat_map(|arg| arg.walk())); |
| inputs.extend(trait_ref.substs.iter()); |
| } |
| |
| // In an inherent impl, we assume that the receiver type and all its |
| // constituents are well-formed. |
| NodeKind::InherentImpl => { |
| let self_ty = tcx.type_of(def_id); |
| inputs.extend(self_ty.walk()); |
| } |
| |
| // In an fn, we assume that the arguments and all their constituents are |
| // well-formed. |
| NodeKind::Fn => { |
| let fn_sig = tcx.fn_sig(def_id); |
| let fn_sig = tcx.liberate_late_bound_regions(def_id, fn_sig); |
| |
| inputs.extend(fn_sig.inputs().iter().flat_map(|ty| ty.walk())); |
| } |
| |
| NodeKind::Other => (), |
| } |
| let input_clauses = inputs.into_iter().filter_map(|arg| { |
| match arg.unpack() { |
| GenericArgKind::Type(ty) => { |
| let binder = Binder::dummy(PredicateKind::TypeWellFormedFromEnv(ty)); |
| Some(tcx.mk_predicate(binder)) |
| } |
| |
| // FIXME(eddyb) no WF conditions from lifetimes? |
| GenericArgKind::Lifetime(_) => None, |
| |
| // FIXME(eddyb) support const generics in Chalk |
| GenericArgKind::Const(_) => None, |
| } |
| }); |
| |
| tcx.mk_predicates(clauses.chain(input_clauses)) |
| } |
| |
| fn param_env_reveal_all_normalized(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> { |
| tcx.param_env(def_id).with_reveal_all_normalized(tcx) |
| } |
| |
| fn instance_def_size_estimate<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| instance_def: ty::InstanceDef<'tcx>, |
| ) -> usize { |
| use ty::InstanceDef; |
| |
| match instance_def { |
| InstanceDef::Item(..) | InstanceDef::DropGlue(..) => { |
| let mir = tcx.instance_mir(instance_def); |
| mir.basic_blocks().iter().map(|bb| bb.statements.len() + 1).sum() |
| } |
| // Estimate the size of other compiler-generated shims to be 1. |
| _ => 1, |
| } |
| } |
| |
| /// If `def_id` is an issue 33140 hack impl, returns its self type; otherwise, returns `None`. |
| /// |
| /// See [`ty::ImplOverlapKind::Issue33140`] for more details. |
| fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Ty<'_>> { |
| debug!("issue33140_self_ty({:?})", def_id); |
| |
| let trait_ref = tcx |
| .impl_trait_ref(def_id) |
| .unwrap_or_else(|| bug!("issue33140_self_ty called on inherent impl {:?}", def_id)); |
| |
| debug!("issue33140_self_ty({:?}), trait-ref={:?}", def_id, trait_ref); |
| |
| let is_marker_like = tcx.impl_polarity(def_id) == ty::ImplPolarity::Positive |
| && tcx.associated_item_def_ids(trait_ref.def_id).is_empty(); |
| |
| // Check whether these impls would be ok for a marker trait. |
| if !is_marker_like { |
| debug!("issue33140_self_ty - not marker-like!"); |
| return None; |
| } |
| |
| // impl must be `impl Trait for dyn Marker1 + Marker2 + ...` |
| if trait_ref.substs.len() != 1 { |
| debug!("issue33140_self_ty - impl has substs!"); |
| return None; |
| } |
| |
| let predicates = tcx.predicates_of(def_id); |
| if predicates.parent.is_some() || !predicates.predicates.is_empty() { |
| debug!("issue33140_self_ty - impl has predicates {:?}!", predicates); |
| return None; |
| } |
| |
| let self_ty = trait_ref.self_ty(); |
| let self_ty_matches = match self_ty.kind() { |
| ty::Dynamic(ref data, re) if re.is_static() => data.principal().is_none(), |
| _ => false, |
| }; |
| |
| if self_ty_matches { |
| debug!("issue33140_self_ty - MATCHES!"); |
| Some(self_ty) |
| } else { |
| debug!("issue33140_self_ty - non-matching self type"); |
| None |
| } |
| } |
| |
| /// Check if a function is async. |
| fn asyncness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::IsAsync { |
| let node = tcx.hir().get_by_def_id(def_id.expect_local()); |
| if let Some(fn_kind) = node.fn_kind() { fn_kind.asyncness() } else { hir::IsAsync::NotAsync } |
| } |
| |
| /// Don't call this directly: use ``tcx.conservative_is_privately_uninhabited`` instead. |
| #[instrument(level = "debug", skip(tcx))] |
| pub fn conservative_is_privately_uninhabited_raw<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| param_env_and: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, |
| ) -> bool { |
| let (param_env, ty) = param_env_and.into_parts(); |
| match ty.kind() { |
| ty::Never => { |
| debug!("ty::Never =>"); |
| true |
| } |
| ty::Adt(def, _) if def.is_union() => { |
| debug!("ty::Adt(def, _) if def.is_union() =>"); |
| // For now, `union`s are never considered uninhabited. |
| false |
| } |
| ty::Adt(def, substs) => { |
| debug!("ty::Adt(def, _) if def.is_not_union() =>"); |
| // Any ADT is uninhabited if either: |
| // (a) It has no variants (i.e. an empty `enum`); |
| // (b) Each of its variants (a single one in the case of a `struct`) has at least |
| // one uninhabited field. |
| def.variants().iter().all(|var| { |
| var.fields.iter().any(|field| { |
| let ty = tcx.type_of(field.did).subst(tcx, substs); |
| tcx.conservative_is_privately_uninhabited(param_env.and(ty)) |
| }) |
| }) |
| } |
| ty::Tuple(fields) => { |
| debug!("ty::Tuple(..) =>"); |
| fields.iter().any(|ty| tcx.conservative_is_privately_uninhabited(param_env.and(ty))) |
| } |
| ty::Array(ty, len) => { |
| debug!("ty::Array(ty, len) =>"); |
| match len.try_eval_usize(tcx, param_env) { |
| Some(0) | None => false, |
| // If the array is definitely non-empty, it's uninhabited if |
| // the type of its elements is uninhabited. |
| Some(1..) => tcx.conservative_is_privately_uninhabited(param_env.and(*ty)), |
| } |
| } |
| ty::Ref(..) => { |
| debug!("ty::Ref(..) =>"); |
| // References to uninitialised memory is valid for any type, including |
| // uninhabited types, in unsafe code, so we treat all references as |
| // inhabited. |
| false |
| } |
| _ => { |
| debug!("_ =>"); |
| false |
| } |
| } |
| } |
| |
| pub fn provide(providers: &mut ty::query::Providers) { |
| *providers = ty::query::Providers { |
| asyncness, |
| adt_sized_constraint, |
| def_ident_span, |
| param_env, |
| param_env_reveal_all_normalized, |
| instance_def_size_estimate, |
| issue33140_self_ty, |
| impl_defaultness, |
| conservative_is_privately_uninhabited: conservative_is_privately_uninhabited_raw, |
| ..*providers |
| }; |
| } |
