| use crate::check::{FnCtxt, Inherited}; |
| use crate::constrained_generic_params::{identify_constrained_generic_params, Parameter}; |
| |
| use rustc_ast as ast; |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder}; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{DefId, LocalDefId}; |
| use rustc_hir::intravisit as hir_visit; |
| use rustc_hir::intravisit::Visitor; |
| use rustc_hir::itemlikevisit::ParItemLikeVisitor; |
| use rustc_hir::lang_items::LangItem; |
| use rustc_hir::ItemKind; |
| use rustc_middle::hir::map as hir_map; |
| use rustc_middle::ty::subst::{InternalSubsts, Subst}; |
| use rustc_middle::ty::trait_def::TraitSpecializationKind; |
| use rustc_middle::ty::{ |
| self, AdtKind, GenericParamDefKind, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness, |
| }; |
| use rustc_session::parse::feature_err; |
| use rustc_span::symbol::{sym, Ident, Symbol}; |
| use rustc_span::Span; |
| use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt; |
| use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode, WellFormedLoc}; |
| |
| use std::convert::TryInto; |
| use std::iter; |
| use std::ops::ControlFlow; |
| |
| /// Helper type of a temporary returned by `.for_item(...)`. |
| /// This is necessary because we can't write the following bound: |
| /// |
| /// ```rust |
| /// F: for<'b, 'tcx> where 'tcx FnOnce(FnCtxt<'b, 'tcx>) |
| /// ``` |
| struct CheckWfFcxBuilder<'tcx> { |
| inherited: super::InheritedBuilder<'tcx>, |
| id: hir::HirId, |
| span: Span, |
| param_env: ty::ParamEnv<'tcx>, |
| } |
| |
| impl<'tcx> CheckWfFcxBuilder<'tcx> { |
| fn with_fcx<F>(&mut self, f: F) |
| where |
| F: for<'b> FnOnce(&FnCtxt<'b, 'tcx>) -> FxHashSet<Ty<'tcx>>, |
| { |
| let id = self.id; |
| let span = self.span; |
| let param_env = self.param_env; |
| self.inherited.enter(|inh| { |
| let fcx = FnCtxt::new(&inh, param_env, id); |
| if !inh.tcx.features().trivial_bounds { |
| // As predicates are cached rather than obligations, this |
| // needs to be called first so that they are checked with an |
| // empty `param_env`. |
| check_false_global_bounds(&fcx, span, id); |
| } |
| let wf_tys = f(&fcx); |
| fcx.select_all_obligations_or_error(); |
| fcx.regionck_item(id, span, wf_tys); |
| }); |
| } |
| } |
| |
| /// Checks that the field types (in a struct def'n) or argument types (in an enum def'n) are |
| /// well-formed, meaning that they do not require any constraints not declared in the struct |
| /// definition itself. For example, this definition would be illegal: |
| /// |
| /// ```rust |
| /// struct Ref<'a, T> { x: &'a T } |
| /// ``` |
| /// |
| /// because the type did not declare that `T:'a`. |
| /// |
| /// We do this check as a pre-pass before checking fn bodies because if these constraints are |
| /// not included it frequently leads to confusing errors in fn bodies. So it's better to check |
| /// the types first. |
| #[instrument(skip(tcx), level = "debug")] |
| pub fn check_item_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) { |
| let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); |
| let item = tcx.hir().expect_item(hir_id); |
| |
| debug!( |
| ?item.def_id, |
| item.name = ? tcx.def_path_str(def_id.to_def_id()) |
| ); |
| |
| match item.kind { |
| // Right now we check that every default trait implementation |
| // has an implementation of itself. Basically, a case like: |
| // |
| // impl Trait for T {} |
| // |
| // has a requirement of `T: Trait` which was required for default |
| // method implementations. Although this could be improved now that |
| // there's a better infrastructure in place for this, it's being left |
| // for a follow-up work. |
| // |
| // Since there's such a requirement, we need to check *just* positive |
| // implementations, otherwise things like: |
| // |
| // impl !Send for T {} |
| // |
| // won't be allowed unless there's an *explicit* implementation of `Send` |
| // for `T` |
| hir::ItemKind::Impl(ref impl_) => { |
| let is_auto = tcx |
| .impl_trait_ref(item.def_id) |
| .map_or(false, |trait_ref| tcx.trait_is_auto(trait_ref.def_id)); |
| if let (hir::Defaultness::Default { .. }, true) = (impl_.defaultness, is_auto) { |
| let sp = impl_.of_trait.as_ref().map_or(item.span, |t| t.path.span); |
| let mut err = |
| tcx.sess.struct_span_err(sp, "impls of auto traits cannot be default"); |
| err.span_labels(impl_.defaultness_span, "default because of this"); |
| err.span_label(sp, "auto trait"); |
| err.emit(); |
| } |
| // We match on both `ty::ImplPolarity` and `ast::ImplPolarity` just to get the `!` span. |
| match (tcx.impl_polarity(def_id), impl_.polarity) { |
| (ty::ImplPolarity::Positive, _) => { |
| check_impl(tcx, item, impl_.self_ty, &impl_.of_trait); |
| } |
| (ty::ImplPolarity::Negative, ast::ImplPolarity::Negative(span)) => { |
| // FIXME(#27579): what amount of WF checking do we need for neg impls? |
| if let hir::Defaultness::Default { .. } = impl_.defaultness { |
| let mut spans = vec![span]; |
| spans.extend(impl_.defaultness_span); |
| struct_span_err!( |
| tcx.sess, |
| spans, |
| E0750, |
| "negative impls cannot be default impls" |
| ) |
| .emit(); |
| } |
| } |
| (ty::ImplPolarity::Reservation, _) => { |
| // FIXME: what amount of WF checking do we need for reservation impls? |
| } |
| _ => unreachable!(), |
| } |
| } |
| hir::ItemKind::Fn(ref sig, ..) => { |
| check_item_fn(tcx, item.def_id, item.ident, item.span, sig.decl); |
| } |
| hir::ItemKind::Static(ty, ..) => { |
| check_item_type(tcx, item.def_id, ty.span, false); |
| } |
| hir::ItemKind::Const(ty, ..) => { |
| check_item_type(tcx, item.def_id, ty.span, false); |
| } |
| hir::ItemKind::ForeignMod { items, .. } => { |
| for it in items.iter() { |
| let it = tcx.hir().foreign_item(it.id); |
| match it.kind { |
| hir::ForeignItemKind::Fn(decl, ..) => { |
| check_item_fn(tcx, it.def_id, it.ident, it.span, decl) |
| } |
| hir::ForeignItemKind::Static(ty, ..) => { |
| check_item_type(tcx, it.def_id, ty.span, true) |
| } |
| hir::ForeignItemKind::Type => (), |
| } |
| } |
| } |
| hir::ItemKind::Struct(ref struct_def, ref ast_generics) => { |
| check_type_defn(tcx, item, false, |fcx| vec![fcx.non_enum_variant(struct_def)]); |
| |
| check_variances_for_type_defn(tcx, item, ast_generics); |
| } |
| hir::ItemKind::Union(ref struct_def, ref ast_generics) => { |
| check_type_defn(tcx, item, true, |fcx| vec![fcx.non_enum_variant(struct_def)]); |
| |
| check_variances_for_type_defn(tcx, item, ast_generics); |
| } |
| hir::ItemKind::Enum(ref enum_def, ref ast_generics) => { |
| check_type_defn(tcx, item, true, |fcx| fcx.enum_variants(enum_def)); |
| |
| check_variances_for_type_defn(tcx, item, ast_generics); |
| } |
| hir::ItemKind::Trait(..) => { |
| check_trait(tcx, item); |
| } |
| hir::ItemKind::TraitAlias(..) => { |
| check_trait(tcx, item); |
| } |
| _ => {} |
| } |
| } |
| |
| pub fn check_trait_item(tcx: TyCtxt<'_>, def_id: LocalDefId) { |
| let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); |
| let trait_item = tcx.hir().expect_trait_item(hir_id); |
| |
| let (method_sig, span) = match trait_item.kind { |
| hir::TraitItemKind::Fn(ref sig, _) => (Some(sig), trait_item.span), |
| hir::TraitItemKind::Type(_bounds, Some(ty)) => (None, ty.span), |
| _ => (None, trait_item.span), |
| }; |
| check_object_unsafe_self_trait_by_name(tcx, trait_item); |
| check_associated_item(tcx, trait_item.def_id, span, method_sig); |
| |
| let encl_trait_hir_id = tcx.hir().get_parent_item(hir_id); |
| let encl_trait = tcx.hir().expect_item(encl_trait_hir_id); |
| let encl_trait_def_id = encl_trait.def_id.to_def_id(); |
| let fn_lang_item_name = if Some(encl_trait_def_id) == tcx.lang_items().fn_trait() { |
| Some("fn") |
| } else if Some(encl_trait_def_id) == tcx.lang_items().fn_mut_trait() { |
| Some("fn_mut") |
| } else { |
| None |
| }; |
| |
| if let (Some(fn_lang_item_name), "call") = |
| (fn_lang_item_name, trait_item.ident.name.to_ident_string().as_str()) |
| { |
| // We are looking at the `call` function of the `fn` or `fn_mut` lang item. |
| // Do some rudimentary sanity checking to avoid an ICE later (issue #83471). |
| if let Some(hir::FnSig { decl, span, .. }) = method_sig { |
| if let [self_ty, _] = decl.inputs { |
| if !matches!(self_ty.kind, hir::TyKind::Rptr(_, _)) { |
| tcx.sess |
| .struct_span_err( |
| self_ty.span, |
| &format!( |
| "first argument of `call` in `{}` lang item must be a reference", |
| fn_lang_item_name |
| ), |
| ) |
| .emit(); |
| } |
| } else { |
| tcx.sess |
| .struct_span_err( |
| *span, |
| &format!( |
| "`call` function in `{}` lang item takes exactly two arguments", |
| fn_lang_item_name |
| ), |
| ) |
| .emit(); |
| } |
| } else { |
| tcx.sess |
| .struct_span_err( |
| trait_item.span, |
| &format!( |
| "`call` trait item in `{}` lang item must be a function", |
| fn_lang_item_name |
| ), |
| ) |
| .emit(); |
| } |
| } |
| } |
| |
| fn could_be_self(trait_def_id: LocalDefId, ty: &hir::Ty<'_>) -> bool { |
| match ty.kind { |
| hir::TyKind::TraitObject([trait_ref], ..) => match trait_ref.trait_ref.path.segments { |
| [s] => s.res.and_then(|r| r.opt_def_id()) == Some(trait_def_id.to_def_id()), |
| _ => false, |
| }, |
| _ => false, |
| } |
| } |
| |
| /// Detect when an object unsafe trait is referring to itself in one of its associated items. |
| /// When this is done, suggest using `Self` instead. |
| fn check_object_unsafe_self_trait_by_name(tcx: TyCtxt<'_>, item: &hir::TraitItem<'_>) { |
| let (trait_name, trait_def_id) = match tcx.hir().get(tcx.hir().get_parent_item(item.hir_id())) { |
| hir::Node::Item(item) => match item.kind { |
| hir::ItemKind::Trait(..) => (item.ident, item.def_id), |
| _ => return, |
| }, |
| _ => return, |
| }; |
| let mut trait_should_be_self = vec![]; |
| match &item.kind { |
| hir::TraitItemKind::Const(ty, _) | hir::TraitItemKind::Type(_, Some(ty)) |
| if could_be_self(trait_def_id, ty) => |
| { |
| trait_should_be_self.push(ty.span) |
| } |
| hir::TraitItemKind::Fn(sig, _) => { |
| for ty in sig.decl.inputs { |
| if could_be_self(trait_def_id, ty) { |
| trait_should_be_self.push(ty.span); |
| } |
| } |
| match sig.decl.output { |
| hir::FnRetTy::Return(ty) if could_be_self(trait_def_id, ty) => { |
| trait_should_be_self.push(ty.span); |
| } |
| _ => {} |
| } |
| } |
| _ => {} |
| } |
| if !trait_should_be_self.is_empty() { |
| if tcx.object_safety_violations(trait_def_id).is_empty() { |
| return; |
| } |
| let sugg = trait_should_be_self.iter().map(|span| (*span, "Self".to_string())).collect(); |
| tcx.sess |
| .struct_span_err( |
| trait_should_be_self, |
| "associated item referring to unboxed trait object for its own trait", |
| ) |
| .span_label(trait_name.span, "in this trait") |
| .multipart_suggestion( |
| "you might have meant to use `Self` to refer to the implementing type", |
| sugg, |
| Applicability::MachineApplicable, |
| ) |
| .emit(); |
| } |
| } |
| |
| pub fn check_impl_item(tcx: TyCtxt<'_>, def_id: LocalDefId) { |
| let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); |
| let impl_item = tcx.hir().expect_impl_item(hir_id); |
| |
| let (method_sig, span) = match impl_item.kind { |
| hir::ImplItemKind::Fn(ref sig, _) => (Some(sig), impl_item.span), |
| hir::ImplItemKind::TyAlias(ty) => (None, ty.span), |
| _ => (None, impl_item.span), |
| }; |
| |
| check_associated_item(tcx, impl_item.def_id, span, method_sig); |
| } |
| |
| fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) { |
| match param.kind { |
| // We currently only check wf of const params here. |
| hir::GenericParamKind::Lifetime { .. } | hir::GenericParamKind::Type { .. } => (), |
| |
| // Const parameters are well formed if their type is structural match. |
| // FIXME(const_generics_defaults): we also need to check that the `default` is wf. |
| hir::GenericParamKind::Const { ty: hir_ty, default: _ } => { |
| let ty = tcx.type_of(tcx.hir().local_def_id(param.hir_id)); |
| |
| let err_ty_str; |
| let mut is_ptr = true; |
| let err = if tcx.features().adt_const_params { |
| match ty.peel_refs().kind() { |
| ty::FnPtr(_) => Some("function pointers"), |
| ty::RawPtr(_) => Some("raw pointers"), |
| _ => None, |
| } |
| } else { |
| match ty.kind() { |
| ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Error(_) => None, |
| ty::FnPtr(_) => Some("function pointers"), |
| ty::RawPtr(_) => Some("raw pointers"), |
| _ => { |
| is_ptr = false; |
| err_ty_str = format!("`{}`", ty); |
| Some(err_ty_str.as_str()) |
| } |
| } |
| }; |
| if let Some(unsupported_type) = err { |
| if is_ptr { |
| tcx.sess.span_err( |
| hir_ty.span, |
| &format!( |
| "using {} as const generic parameters is forbidden", |
| unsupported_type |
| ), |
| ) |
| } else { |
| let mut err = tcx.sess.struct_span_err( |
| hir_ty.span, |
| &format!( |
| "{} is forbidden as the type of a const generic parameter", |
| unsupported_type |
| ), |
| ); |
| err.note("the only supported types are integers, `bool` and `char`"); |
| if tcx.sess.is_nightly_build() { |
| err.help( |
| "more complex types are supported with `#![feature(adt_const_params)]`", |
| ); |
| } |
| err.emit() |
| } |
| }; |
| |
| if traits::search_for_structural_match_violation(param.hir_id, param.span, tcx, ty) |
| .is_some() |
| { |
| // We use the same error code in both branches, because this is really the same |
| // issue: we just special-case the message for type parameters to make it |
| // clearer. |
| if let ty::Param(_) = ty.peel_refs().kind() { |
| // Const parameters may not have type parameters as their types, |
| // because we cannot be sure that the type parameter derives `PartialEq` |
| // and `Eq` (just implementing them is not enough for `structural_match`). |
| struct_span_err!( |
| tcx.sess, |
| hir_ty.span, |
| E0741, |
| "`{}` is not guaranteed to `#[derive(PartialEq, Eq)]`, so may not be \ |
| used as the type of a const parameter", |
| ty, |
| ) |
| .span_label( |
| hir_ty.span, |
| format!("`{}` may not derive both `PartialEq` and `Eq`", ty), |
| ) |
| .note( |
| "it is not currently possible to use a type parameter as the type of a \ |
| const parameter", |
| ) |
| .emit(); |
| } else { |
| struct_span_err!( |
| tcx.sess, |
| hir_ty.span, |
| E0741, |
| "`{}` must be annotated with `#[derive(PartialEq, Eq)]` to be used as \ |
| the type of a const parameter", |
| ty, |
| ) |
| .span_label( |
| hir_ty.span, |
| format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty), |
| ) |
| .emit(); |
| } |
| } |
| } |
| } |
| } |
| |
| #[tracing::instrument(level = "debug", skip(tcx, span, sig_if_method))] |
| fn check_associated_item( |
| tcx: TyCtxt<'_>, |
| item_id: LocalDefId, |
| span: Span, |
| sig_if_method: Option<&hir::FnSig<'_>>, |
| ) { |
| let code = ObligationCauseCode::WellFormed(Some(WellFormedLoc::Ty(item_id))); |
| for_id(tcx, item_id, span).with_fcx(|fcx| { |
| let item = fcx.tcx.associated_item(item_id); |
| |
| let (mut implied_bounds, self_ty) = match item.container { |
| ty::TraitContainer(_) => (FxHashSet::default(), fcx.tcx.types.self_param), |
| ty::ImplContainer(def_id) => { |
| (fcx.impl_implied_bounds(def_id, span), fcx.tcx.type_of(def_id)) |
| } |
| }; |
| |
| match item.kind { |
| ty::AssocKind::Const => { |
| let ty = fcx.tcx.type_of(item.def_id); |
| let ty = fcx.normalize_associated_types_in_wf(span, ty, WellFormedLoc::Ty(item_id)); |
| fcx.register_wf_obligation(ty.into(), span, code.clone()); |
| } |
| ty::AssocKind::Fn => { |
| let sig = fcx.tcx.fn_sig(item.def_id); |
| let hir_sig = sig_if_method.expect("bad signature for method"); |
| check_fn_or_method( |
| fcx, |
| item.ident.span, |
| sig, |
| hir_sig.decl, |
| item.def_id, |
| &mut implied_bounds, |
| ); |
| check_method_receiver(fcx, hir_sig, item, self_ty); |
| } |
| ty::AssocKind::Type => { |
| if let ty::AssocItemContainer::TraitContainer(_) = item.container { |
| check_associated_type_bounds(fcx, item, span) |
| } |
| if item.defaultness.has_value() { |
| let ty = fcx.tcx.type_of(item.def_id); |
| let ty = |
| fcx.normalize_associated_types_in_wf(span, ty, WellFormedLoc::Ty(item_id)); |
| fcx.register_wf_obligation(ty.into(), span, code.clone()); |
| } |
| } |
| } |
| |
| implied_bounds |
| }) |
| } |
| |
| fn for_item<'tcx>(tcx: TyCtxt<'tcx>, item: &hir::Item<'_>) -> CheckWfFcxBuilder<'tcx> { |
| for_id(tcx, item.def_id, item.span) |
| } |
| |
| fn for_id(tcx: TyCtxt<'_>, def_id: LocalDefId, span: Span) -> CheckWfFcxBuilder<'_> { |
| CheckWfFcxBuilder { |
| inherited: Inherited::build(tcx, def_id), |
| id: hir::HirId::make_owner(def_id), |
| span, |
| param_env: tcx.param_env(def_id), |
| } |
| } |
| |
| fn item_adt_kind(kind: &ItemKind<'_>) -> Option<AdtKind> { |
| match kind { |
| ItemKind::Struct(..) => Some(AdtKind::Struct), |
| ItemKind::Union(..) => Some(AdtKind::Union), |
| ItemKind::Enum(..) => Some(AdtKind::Enum), |
| _ => None, |
| } |
| } |
| |
| /// In a type definition, we check that to ensure that the types of the fields are well-formed. |
| fn check_type_defn<'tcx, F>( |
| tcx: TyCtxt<'tcx>, |
| item: &hir::Item<'tcx>, |
| all_sized: bool, |
| mut lookup_fields: F, |
| ) where |
| F: for<'fcx> FnMut(&FnCtxt<'fcx, 'tcx>) -> Vec<AdtVariant<'tcx>>, |
| { |
| for_item(tcx, item).with_fcx(|fcx| { |
| let variants = lookup_fields(fcx); |
| let packed = tcx.adt_def(item.def_id).repr.packed(); |
| |
| for variant in &variants { |
| // For DST, or when drop needs to copy things around, all |
| // intermediate types must be sized. |
| let needs_drop_copy = || { |
| packed && { |
| let ty = variant.fields.last().unwrap().ty; |
| let ty = tcx.erase_regions(ty); |
| if ty.needs_infer() { |
| tcx.sess |
| .delay_span_bug(item.span, &format!("inference variables in {:?}", ty)); |
| // Just treat unresolved type expression as if it needs drop. |
| true |
| } else { |
| ty.needs_drop(tcx, tcx.param_env(item.def_id)) |
| } |
| } |
| }; |
| let all_sized = all_sized || variant.fields.is_empty() || needs_drop_copy(); |
| let unsized_len = if all_sized { 0 } else { 1 }; |
| for (idx, field) in |
| variant.fields[..variant.fields.len() - unsized_len].iter().enumerate() |
| { |
| let last = idx == variant.fields.len() - 1; |
| fcx.register_bound( |
| field.ty, |
| tcx.require_lang_item(LangItem::Sized, None), |
| traits::ObligationCause::new( |
| field.span, |
| fcx.body_id, |
| traits::FieldSized { |
| adt_kind: match item_adt_kind(&item.kind) { |
| Some(i) => i, |
| None => bug!(), |
| }, |
| span: field.span, |
| last, |
| }, |
| ), |
| ); |
| } |
| |
| // All field types must be well-formed. |
| for field in &variant.fields { |
| fcx.register_wf_obligation( |
| field.ty.into(), |
| field.span, |
| ObligationCauseCode::WellFormed(Some(WellFormedLoc::Ty(field.def_id))), |
| ) |
| } |
| |
| // Explicit `enum` discriminant values must const-evaluate successfully. |
| if let Some(discr_def_id) = variant.explicit_discr { |
| let discr_substs = InternalSubsts::identity_for_item(tcx, discr_def_id.to_def_id()); |
| |
| let cause = traits::ObligationCause::new( |
| tcx.def_span(discr_def_id), |
| fcx.body_id, |
| traits::MiscObligation, |
| ); |
| fcx.register_predicate(traits::Obligation::new( |
| cause, |
| fcx.param_env, |
| ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(ty::Unevaluated::new( |
| ty::WithOptConstParam::unknown(discr_def_id.to_def_id()), |
| discr_substs, |
| ))) |
| .to_predicate(tcx), |
| )); |
| } |
| } |
| |
| check_where_clauses(fcx, item.span, item.def_id.to_def_id(), None); |
| |
| // No implied bounds in a struct definition. |
| FxHashSet::default() |
| }); |
| } |
| |
| #[instrument(skip(tcx, item))] |
| fn check_trait(tcx: TyCtxt<'_>, item: &hir::Item<'_>) { |
| debug!(?item.def_id); |
| |
| let trait_def = tcx.trait_def(item.def_id); |
| if trait_def.is_marker |
| || matches!(trait_def.specialization_kind, TraitSpecializationKind::Marker) |
| { |
| for associated_def_id in &*tcx.associated_item_def_ids(item.def_id) { |
| struct_span_err!( |
| tcx.sess, |
| tcx.def_span(*associated_def_id), |
| E0714, |
| "marker traits cannot have associated items", |
| ) |
| .emit(); |
| } |
| } |
| |
| // FIXME: this shouldn't use an `FnCtxt` at all. |
| for_item(tcx, item).with_fcx(|fcx| { |
| check_where_clauses(fcx, item.span, item.def_id.to_def_id(), None); |
| |
| FxHashSet::default() |
| }); |
| } |
| |
| /// Checks all associated type defaults of trait `trait_def_id`. |
| /// |
| /// Assuming the defaults are used, check that all predicates (bounds on the |
| /// assoc type and where clauses on the trait) hold. |
| fn check_associated_type_bounds(fcx: &FnCtxt<'_, '_>, item: &ty::AssocItem, span: Span) { |
| let tcx = fcx.tcx; |
| |
| let bounds = tcx.explicit_item_bounds(item.def_id); |
| |
| debug!("check_associated_type_bounds: bounds={:?}", bounds); |
| let wf_obligations = bounds.iter().flat_map(|&(bound, bound_span)| { |
| let normalized_bound = fcx.normalize_associated_types_in(span, bound); |
| traits::wf::predicate_obligations( |
| fcx, |
| fcx.param_env, |
| fcx.body_id, |
| normalized_bound, |
| bound_span, |
| ) |
| }); |
| |
| for obligation in wf_obligations { |
| debug!("next obligation cause: {:?}", obligation.cause); |
| fcx.register_predicate(obligation); |
| } |
| } |
| |
| fn check_item_fn( |
| tcx: TyCtxt<'_>, |
| def_id: LocalDefId, |
| ident: Ident, |
| span: Span, |
| decl: &hir::FnDecl<'_>, |
| ) { |
| for_id(tcx, def_id, span).with_fcx(|fcx| { |
| let sig = tcx.fn_sig(def_id); |
| let mut implied_bounds = FxHashSet::default(); |
| check_fn_or_method(fcx, ident.span, sig, decl, def_id.to_def_id(), &mut implied_bounds); |
| implied_bounds |
| }) |
| } |
| |
| fn check_item_type(tcx: TyCtxt<'_>, item_id: LocalDefId, ty_span: Span, allow_foreign_ty: bool) { |
| debug!("check_item_type: {:?}", item_id); |
| |
| for_id(tcx, item_id, ty_span).with_fcx(|fcx| { |
| let ty = tcx.type_of(item_id); |
| let item_ty = fcx.normalize_associated_types_in_wf(ty_span, ty, WellFormedLoc::Ty(item_id)); |
| |
| let mut forbid_unsized = true; |
| if allow_foreign_ty { |
| let tail = fcx.tcx.struct_tail_erasing_lifetimes(item_ty, fcx.param_env); |
| if let ty::Foreign(_) = tail.kind() { |
| forbid_unsized = false; |
| } |
| } |
| |
| fcx.register_wf_obligation( |
| item_ty.into(), |
| ty_span, |
| ObligationCauseCode::WellFormed(Some(WellFormedLoc::Ty(item_id))), |
| ); |
| if forbid_unsized { |
| fcx.register_bound( |
| item_ty, |
| tcx.require_lang_item(LangItem::Sized, None), |
| traits::ObligationCause::new(ty_span, fcx.body_id, traits::MiscObligation), |
| ); |
| } |
| |
| // No implied bounds in a const, etc. |
| FxHashSet::default() |
| }); |
| } |
| |
| #[tracing::instrument(level = "debug", skip(tcx, ast_self_ty, ast_trait_ref))] |
| fn check_impl<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| item: &'tcx hir::Item<'tcx>, |
| ast_self_ty: &hir::Ty<'_>, |
| ast_trait_ref: &Option<hir::TraitRef<'_>>, |
| ) { |
| for_item(tcx, item).with_fcx(|fcx| { |
| match *ast_trait_ref { |
| Some(ref ast_trait_ref) => { |
| // `#[rustc_reservation_impl]` impls are not real impls and |
| // therefore don't need to be WF (the trait's `Self: Trait` predicate |
| // won't hold). |
| let trait_ref = tcx.impl_trait_ref(item.def_id).unwrap(); |
| let trait_ref = |
| fcx.normalize_associated_types_in(ast_trait_ref.path.span, trait_ref); |
| let obligations = traits::wf::trait_obligations( |
| fcx, |
| fcx.param_env, |
| fcx.body_id, |
| &trait_ref, |
| ast_trait_ref.path.span, |
| Some(item), |
| ); |
| debug!(?obligations); |
| for obligation in obligations { |
| fcx.register_predicate(obligation); |
| } |
| } |
| None => { |
| let self_ty = tcx.type_of(item.def_id); |
| let self_ty = fcx.normalize_associated_types_in(item.span, self_ty); |
| fcx.register_wf_obligation( |
| self_ty.into(), |
| ast_self_ty.span, |
| ObligationCauseCode::WellFormed(Some(WellFormedLoc::Ty( |
| item.hir_id().expect_owner(), |
| ))), |
| ); |
| } |
| } |
| |
| check_where_clauses(fcx, item.span, item.def_id.to_def_id(), None); |
| |
| fcx.impl_implied_bounds(item.def_id.to_def_id(), item.span) |
| }); |
| } |
| |
| /// Checks where-clauses and inline bounds that are declared on `def_id`. |
| #[instrument(skip(fcx), level = "debug")] |
| fn check_where_clauses<'tcx, 'fcx>( |
| fcx: &FnCtxt<'fcx, 'tcx>, |
| span: Span, |
| def_id: DefId, |
| return_ty: Option<(Ty<'tcx>, Span)>, |
| ) { |
| let tcx = fcx.tcx; |
| |
| let predicates = tcx.predicates_of(def_id); |
| let generics = tcx.generics_of(def_id); |
| |
| let is_our_default = |def: &ty::GenericParamDef| match def.kind { |
| GenericParamDefKind::Type { has_default, .. } |
| | GenericParamDefKind::Const { has_default } => { |
| has_default && def.index >= generics.parent_count as u32 |
| } |
| GenericParamDefKind::Lifetime => unreachable!(), |
| }; |
| |
| // Check that concrete defaults are well-formed. See test `type-check-defaults.rs`. |
| // For example, this forbids the declaration: |
| // |
| // struct Foo<T = Vec<[u32]>> { .. } |
| // |
| // Here, the default `Vec<[u32]>` is not WF because `[u32]: Sized` does not hold. |
| for param in &generics.params { |
| match param.kind { |
| GenericParamDefKind::Type { .. } => { |
| if is_our_default(param) { |
| let ty = tcx.type_of(param.def_id); |
| // Ignore dependent defaults -- that is, where the default of one type |
| // parameter includes another (e.g., `<T, U = T>`). In those cases, we can't |
| // be sure if it will error or not as user might always specify the other. |
| if !ty.definitely_needs_subst(tcx) { |
| fcx.register_wf_obligation( |
| ty.into(), |
| tcx.def_span(param.def_id), |
| ObligationCauseCode::MiscObligation, |
| ); |
| } |
| } |
| } |
| GenericParamDefKind::Const { .. } => { |
| if is_our_default(param) { |
| // FIXME(const_generics_defaults): This |
| // is incorrect when dealing with unused substs, for example |
| // for `struct Foo<const N: usize, const M: usize = { 1 - 2 }>` |
| // we should eagerly error. |
| let default_ct = tcx.const_param_default(param.def_id); |
| if !default_ct.definitely_needs_subst(tcx) { |
| fcx.register_wf_obligation( |
| default_ct.into(), |
| tcx.def_span(param.def_id), |
| ObligationCauseCode::WellFormed(None), |
| ); |
| } |
| } |
| } |
| // Doesn't have defaults. |
| GenericParamDefKind::Lifetime => {} |
| } |
| } |
| |
| // Check that trait predicates are WF when params are substituted by their defaults. |
| // We don't want to overly constrain the predicates that may be written but we want to |
| // catch cases where a default my never be applied such as `struct Foo<T: Copy = String>`. |
| // Therefore we check if a predicate which contains a single type param |
| // with a concrete default is WF with that default substituted. |
| // For more examples see tests `defaults-well-formedness.rs` and `type-check-defaults.rs`. |
| // |
| // First we build the defaulted substitution. |
| let substs = InternalSubsts::for_item(tcx, def_id, |param, _| { |
| match param.kind { |
| GenericParamDefKind::Lifetime => { |
| // All regions are identity. |
| tcx.mk_param_from_def(param) |
| } |
| |
| GenericParamDefKind::Type { .. } => { |
| // If the param has a default, ... |
| if is_our_default(param) { |
| let default_ty = tcx.type_of(param.def_id); |
| // ... and it's not a dependent default, ... |
| if !default_ty.definitely_needs_subst(tcx) { |
| // ... then substitute it with the default. |
| return default_ty.into(); |
| } |
| } |
| |
| tcx.mk_param_from_def(param) |
| } |
| GenericParamDefKind::Const { .. } => { |
| // If the param has a default, ... |
| if is_our_default(param) { |
| let default_ct = tcx.const_param_default(param.def_id); |
| // ... and it's not a dependent default, ... |
| if !default_ct.definitely_needs_subst(tcx) { |
| // ... then substitute it with the default. |
| return default_ct.into(); |
| } |
| } |
| |
| tcx.mk_param_from_def(param) |
| } |
| } |
| }); |
| |
| // Now we build the substituted predicates. |
| let default_obligations = predicates |
| .predicates |
| .iter() |
| .flat_map(|&(pred, sp)| { |
| struct CountParams<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| params: FxHashSet<u32>, |
| } |
| impl<'tcx> ty::fold::TypeVisitor<'tcx> for CountParams<'tcx> { |
| type BreakTy = (); |
| fn tcx_for_anon_const_substs(&self) -> Option<TyCtxt<'tcx>> { |
| Some(self.tcx) |
| } |
| |
| fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { |
| if let ty::Param(param) = t.kind() { |
| self.params.insert(param.index); |
| } |
| t.super_visit_with(self) |
| } |
| |
| fn visit_region(&mut self, _: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> { |
| ControlFlow::BREAK |
| } |
| |
| fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> { |
| if let ty::ConstKind::Param(param) = c.val { |
| self.params.insert(param.index); |
| } |
| c.super_visit_with(self) |
| } |
| } |
| let mut param_count = CountParams { tcx: fcx.tcx, params: FxHashSet::default() }; |
| let has_region = pred.visit_with(&mut param_count).is_break(); |
| let substituted_pred = pred.subst(tcx, substs); |
| // Don't check non-defaulted params, dependent defaults (including lifetimes) |
| // or preds with multiple params. |
| if substituted_pred.definitely_has_param_types_or_consts(tcx) |
| || param_count.params.len() > 1 |
| || has_region |
| { |
| None |
| } else if predicates.predicates.iter().any(|&(p, _)| p == substituted_pred) { |
| // Avoid duplication of predicates that contain no parameters, for example. |
| None |
| } else { |
| Some((substituted_pred, sp)) |
| } |
| }) |
| .map(|(pred, sp)| { |
| // Convert each of those into an obligation. So if you have |
| // something like `struct Foo<T: Copy = String>`, we would |
| // take that predicate `T: Copy`, substitute to `String: Copy` |
| // (actually that happens in the previous `flat_map` call), |
| // and then try to prove it (in this case, we'll fail). |
| // |
| // Note the subtle difference from how we handle `predicates` |
| // below: there, we are not trying to prove those predicates |
| // to be *true* but merely *well-formed*. |
| let pred = fcx.normalize_associated_types_in(sp, pred); |
| let cause = |
| traits::ObligationCause::new(sp, fcx.body_id, traits::ItemObligation(def_id)); |
| traits::Obligation::new(cause, fcx.param_env, pred) |
| }); |
| |
| let predicates = predicates.instantiate_identity(tcx); |
| |
| if let Some((return_ty, _)) = return_ty { |
| if return_ty.has_infer_types_or_consts() { |
| fcx.select_obligations_where_possible(false, |_| {}); |
| } |
| } |
| |
| let predicates = fcx.normalize_associated_types_in(span, predicates); |
| |
| debug!(?predicates.predicates); |
| assert_eq!(predicates.predicates.len(), predicates.spans.len()); |
| let wf_obligations = |
| iter::zip(&predicates.predicates, &predicates.spans).flat_map(|(&p, &sp)| { |
| traits::wf::predicate_obligations(fcx, fcx.param_env, fcx.body_id, p, sp) |
| }); |
| |
| for obligation in wf_obligations.chain(default_obligations) { |
| debug!("next obligation cause: {:?}", obligation.cause); |
| fcx.register_predicate(obligation); |
| } |
| } |
| |
| #[tracing::instrument(level = "debug", skip(fcx, span, hir_decl))] |
| fn check_fn_or_method<'fcx, 'tcx>( |
| fcx: &FnCtxt<'fcx, 'tcx>, |
| span: Span, |
| sig: ty::PolyFnSig<'tcx>, |
| hir_decl: &hir::FnDecl<'_>, |
| def_id: DefId, |
| implied_bounds: &mut FxHashSet<Ty<'tcx>>, |
| ) { |
| let sig = fcx.tcx.liberate_late_bound_regions(def_id, sig); |
| |
| // Unnormalized types in signature are WF too |
| implied_bounds.extend(sig.inputs()); |
| // FIXME(#27579) return types should not be implied bounds |
| implied_bounds.insert(sig.output()); |
| |
| // Normalize the input and output types one at a time, using a different |
| // `WellFormedLoc` for each. We cannot call `normalize_associated_types` |
| // on the entire `FnSig`, since this would use the same `WellFormedLoc` |
| // for each type, preventing the HIR wf check from generating |
| // a nice error message. |
| let ty::FnSig { mut inputs_and_output, c_variadic, unsafety, abi } = sig; |
| inputs_and_output = |
| fcx.tcx.mk_type_list(inputs_and_output.iter().enumerate().map(|(i, ty)| { |
| fcx.normalize_associated_types_in_wf( |
| span, |
| ty, |
| WellFormedLoc::Param { |
| function: def_id.expect_local(), |
| // Note that the `param_idx` of the output type is |
| // one greater than the index of the last input type. |
| param_idx: i.try_into().unwrap(), |
| }, |
| ) |
| })); |
| // Manually call `normalize_assocaited_types_in` on the other types |
| // in `FnSig`. This ensures that if the types of these fields |
| // ever change to include projections, we will start normalizing |
| // them automatically. |
| let sig = ty::FnSig { |
| inputs_and_output, |
| c_variadic: fcx.normalize_associated_types_in(span, c_variadic), |
| unsafety: fcx.normalize_associated_types_in(span, unsafety), |
| abi: fcx.normalize_associated_types_in(span, abi), |
| }; |
| |
| for (i, (&input_ty, ty)) in iter::zip(sig.inputs(), hir_decl.inputs).enumerate() { |
| fcx.register_wf_obligation( |
| input_ty.into(), |
| ty.span, |
| ObligationCauseCode::WellFormed(Some(WellFormedLoc::Param { |
| function: def_id.expect_local(), |
| param_idx: i.try_into().unwrap(), |
| })), |
| ); |
| } |
| |
| implied_bounds.extend(sig.inputs()); |
| |
| fcx.register_wf_obligation( |
| sig.output().into(), |
| hir_decl.output.span(), |
| ObligationCauseCode::ReturnType, |
| ); |
| |
| // FIXME(#27579) return types should not be implied bounds |
| implied_bounds.insert(sig.output()); |
| |
| debug!(?implied_bounds); |
| |
| check_where_clauses(fcx, span, def_id, Some((sig.output(), hir_decl.output.span()))); |
| } |
| |
| const HELP_FOR_SELF_TYPE: &str = "consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, \ |
| `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one \ |
| of the previous types except `Self`)"; |
| |
| #[tracing::instrument(level = "debug", skip(fcx))] |
| fn check_method_receiver<'fcx, 'tcx>( |
| fcx: &FnCtxt<'fcx, 'tcx>, |
| fn_sig: &hir::FnSig<'_>, |
| method: &ty::AssocItem, |
| self_ty: Ty<'tcx>, |
| ) { |
| // Check that the method has a valid receiver type, given the type `Self`. |
| debug!("check_method_receiver({:?}, self_ty={:?})", method, self_ty); |
| |
| if !method.fn_has_self_parameter { |
| return; |
| } |
| |
| let span = fn_sig.decl.inputs[0].span; |
| |
| let sig = fcx.tcx.fn_sig(method.def_id); |
| let sig = fcx.tcx.liberate_late_bound_regions(method.def_id, sig); |
| let sig = fcx.normalize_associated_types_in(span, sig); |
| |
| debug!("check_method_receiver: sig={:?}", sig); |
| |
| let self_ty = fcx.normalize_associated_types_in(span, self_ty); |
| |
| let receiver_ty = sig.inputs()[0]; |
| let receiver_ty = fcx.normalize_associated_types_in(span, receiver_ty); |
| |
| if fcx.tcx.features().arbitrary_self_types { |
| if !receiver_is_valid(fcx, span, receiver_ty, self_ty, true) { |
| // Report error; `arbitrary_self_types` was enabled. |
| e0307(fcx, span, receiver_ty); |
| } |
| } else { |
| if !receiver_is_valid(fcx, span, receiver_ty, self_ty, false) { |
| if receiver_is_valid(fcx, span, receiver_ty, self_ty, true) { |
| // Report error; would have worked with `arbitrary_self_types`. |
| feature_err( |
| &fcx.tcx.sess.parse_sess, |
| sym::arbitrary_self_types, |
| span, |
| &format!( |
| "`{}` cannot be used as the type of `self` without \ |
| the `arbitrary_self_types` feature", |
| receiver_ty, |
| ), |
| ) |
| .help(HELP_FOR_SELF_TYPE) |
| .emit(); |
| } else { |
| // Report error; would not have worked with `arbitrary_self_types`. |
| e0307(fcx, span, receiver_ty); |
| } |
| } |
| } |
| } |
| |
| fn e0307(fcx: &FnCtxt<'fcx, 'tcx>, span: Span, receiver_ty: Ty<'_>) { |
| struct_span_err!( |
| fcx.tcx.sess.diagnostic(), |
| span, |
| E0307, |
| "invalid `self` parameter type: {}", |
| receiver_ty, |
| ) |
| .note("type of `self` must be `Self` or a type that dereferences to it") |
| .help(HELP_FOR_SELF_TYPE) |
| .emit(); |
| } |
| |
| /// Returns whether `receiver_ty` would be considered a valid receiver type for `self_ty`. If |
| /// `arbitrary_self_types` is enabled, `receiver_ty` must transitively deref to `self_ty`, possibly |
| /// through a `*const/mut T` raw pointer. If the feature is not enabled, the requirements are more |
| /// strict: `receiver_ty` must implement `Receiver` and directly implement |
| /// `Deref<Target = self_ty>`. |
| /// |
| /// N.B., there are cases this function returns `true` but causes an error to be emitted, |
| /// particularly when `receiver_ty` derefs to a type that is the same as `self_ty` but has the |
| /// wrong lifetime. Be careful of this if you are calling this function speculatively. |
| fn receiver_is_valid<'fcx, 'tcx>( |
| fcx: &FnCtxt<'fcx, 'tcx>, |
| span: Span, |
| receiver_ty: Ty<'tcx>, |
| self_ty: Ty<'tcx>, |
| arbitrary_self_types_enabled: bool, |
| ) -> bool { |
| let cause = fcx.cause(span, traits::ObligationCauseCode::MethodReceiver); |
| |
| let can_eq_self = |ty| fcx.infcx.can_eq(fcx.param_env, self_ty, ty).is_ok(); |
| |
| // `self: Self` is always valid. |
| if can_eq_self(receiver_ty) { |
| if let Some(mut err) = fcx.demand_eqtype_with_origin(&cause, self_ty, receiver_ty) { |
| err.emit(); |
| } |
| return true; |
| } |
| |
| let mut autoderef = fcx.autoderef(span, receiver_ty); |
| |
| // The `arbitrary_self_types` feature allows raw pointer receivers like `self: *const Self`. |
| if arbitrary_self_types_enabled { |
| autoderef = autoderef.include_raw_pointers(); |
| } |
| |
| // The first type is `receiver_ty`, which we know its not equal to `self_ty`; skip it. |
| autoderef.next(); |
| |
| let receiver_trait_def_id = fcx.tcx.require_lang_item(LangItem::Receiver, None); |
| |
| // Keep dereferencing `receiver_ty` until we get to `self_ty`. |
| loop { |
| if let Some((potential_self_ty, _)) = autoderef.next() { |
| debug!( |
| "receiver_is_valid: potential self type `{:?}` to match `{:?}`", |
| potential_self_ty, self_ty |
| ); |
| |
| if can_eq_self(potential_self_ty) { |
| fcx.register_predicates(autoderef.into_obligations()); |
| |
| if let Some(mut err) = |
| fcx.demand_eqtype_with_origin(&cause, self_ty, potential_self_ty) |
| { |
| err.emit(); |
| } |
| |
| break; |
| } else { |
| // Without `feature(arbitrary_self_types)`, we require that each step in the |
| // deref chain implement `receiver` |
| if !arbitrary_self_types_enabled |
| && !receiver_is_implemented( |
| fcx, |
| receiver_trait_def_id, |
| cause.clone(), |
| potential_self_ty, |
| ) |
| { |
| return false; |
| } |
| } |
| } else { |
| debug!("receiver_is_valid: type `{:?}` does not deref to `{:?}`", receiver_ty, self_ty); |
| // If he receiver already has errors reported due to it, consider it valid to avoid |
| // unnecessary errors (#58712). |
| return receiver_ty.references_error(); |
| } |
| } |
| |
| // Without `feature(arbitrary_self_types)`, we require that `receiver_ty` implements `Receiver`. |
| if !arbitrary_self_types_enabled |
| && !receiver_is_implemented(fcx, receiver_trait_def_id, cause.clone(), receiver_ty) |
| { |
| return false; |
| } |
| |
| true |
| } |
| |
| fn receiver_is_implemented( |
| fcx: &FnCtxt<'_, 'tcx>, |
| receiver_trait_def_id: DefId, |
| cause: ObligationCause<'tcx>, |
| receiver_ty: Ty<'tcx>, |
| ) -> bool { |
| let trait_ref = ty::Binder::dummy(ty::TraitRef { |
| def_id: receiver_trait_def_id, |
| substs: fcx.tcx.mk_substs_trait(receiver_ty, &[]), |
| }); |
| |
| let obligation = traits::Obligation::new( |
| cause, |
| fcx.param_env, |
| trait_ref.without_const().to_predicate(fcx.tcx), |
| ); |
| |
| if fcx.predicate_must_hold_modulo_regions(&obligation) { |
| true |
| } else { |
| debug!( |
| "receiver_is_implemented: type `{:?}` does not implement `Receiver` trait", |
| receiver_ty |
| ); |
| false |
| } |
| } |
| |
| fn check_variances_for_type_defn<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| item: &hir::Item<'tcx>, |
| hir_generics: &hir::Generics<'_>, |
| ) { |
| let ty = tcx.type_of(item.def_id); |
| if tcx.has_error_field(ty) { |
| return; |
| } |
| |
| let ty_predicates = tcx.predicates_of(item.def_id); |
| assert_eq!(ty_predicates.parent, None); |
| let variances = tcx.variances_of(item.def_id); |
| |
| let mut constrained_parameters: FxHashSet<_> = variances |
| .iter() |
| .enumerate() |
| .filter(|&(_, &variance)| variance != ty::Bivariant) |
| .map(|(index, _)| Parameter(index as u32)) |
| .collect(); |
| |
| identify_constrained_generic_params(tcx, ty_predicates, None, &mut constrained_parameters); |
| |
| for (index, _) in variances.iter().enumerate() { |
| if constrained_parameters.contains(&Parameter(index as u32)) { |
| continue; |
| } |
| |
| let param = &hir_generics.params[index]; |
| |
| match param.name { |
| hir::ParamName::Error => {} |
| _ => report_bivariance(tcx, param), |
| } |
| } |
| } |
| |
| fn report_bivariance(tcx: TyCtxt<'_>, param: &rustc_hir::GenericParam<'_>) { |
| let span = param.span; |
| let param_name = param.name.ident().name; |
| let mut err = error_392(tcx, span, param_name); |
| |
| let suggested_marker_id = tcx.lang_items().phantom_data(); |
| // Help is available only in presence of lang items. |
| let msg = if let Some(def_id) = suggested_marker_id { |
| format!( |
| "consider removing `{}`, referring to it in a field, or using a marker such as `{}`", |
| param_name, |
| tcx.def_path_str(def_id), |
| ) |
| } else { |
| format!("consider removing `{}` or referring to it in a field", param_name) |
| }; |
| err.help(&msg); |
| |
| if matches!(param.kind, rustc_hir::GenericParamKind::Type { .. }) { |
| err.help(&format!( |
| "if you intended `{0}` to be a const parameter, use `const {0}: usize` instead", |
| param_name |
| )); |
| } |
| err.emit() |
| } |
| |
| /// Feature gates RFC 2056 -- trivial bounds, checking for global bounds that |
| /// aren't true. |
| fn check_false_global_bounds(fcx: &FnCtxt<'_, '_>, span: Span, id: hir::HirId) { |
| let empty_env = ty::ParamEnv::empty(); |
| |
| let def_id = fcx.tcx.hir().local_def_id(id); |
| let predicates = fcx.tcx.predicates_of(def_id).predicates.iter().map(|(p, _)| *p); |
| // Check elaborated bounds. |
| let implied_obligations = traits::elaborate_predicates(fcx.tcx, predicates); |
| |
| for obligation in implied_obligations { |
| let pred = obligation.predicate; |
| // Match the existing behavior. |
| if pred.is_global(fcx.tcx) && !pred.has_late_bound_regions() { |
| let pred = fcx.normalize_associated_types_in(span, pred); |
| let obligation = traits::Obligation::new( |
| traits::ObligationCause::new(span, id, traits::TrivialBound), |
| empty_env, |
| pred, |
| ); |
| fcx.register_predicate(obligation); |
| } |
| } |
| |
| fcx.select_all_obligations_or_error(); |
| } |
| |
| #[derive(Clone, Copy)] |
| pub struct CheckTypeWellFormedVisitor<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| } |
| |
| impl CheckTypeWellFormedVisitor<'tcx> { |
| pub fn new(tcx: TyCtxt<'tcx>) -> CheckTypeWellFormedVisitor<'tcx> { |
| CheckTypeWellFormedVisitor { tcx } |
| } |
| } |
| |
| impl ParItemLikeVisitor<'tcx> for CheckTypeWellFormedVisitor<'tcx> { |
| fn visit_item(&self, i: &'tcx hir::Item<'tcx>) { |
| Visitor::visit_item(&mut self.clone(), i); |
| } |
| |
| fn visit_trait_item(&self, trait_item: &'tcx hir::TraitItem<'tcx>) { |
| Visitor::visit_trait_item(&mut self.clone(), trait_item); |
| } |
| |
| fn visit_impl_item(&self, impl_item: &'tcx hir::ImplItem<'tcx>) { |
| Visitor::visit_impl_item(&mut self.clone(), impl_item); |
| } |
| |
| fn visit_foreign_item(&self, foreign_item: &'tcx hir::ForeignItem<'tcx>) { |
| Visitor::visit_foreign_item(&mut self.clone(), foreign_item) |
| } |
| } |
| |
| impl Visitor<'tcx> for CheckTypeWellFormedVisitor<'tcx> { |
| type Map = hir_map::Map<'tcx>; |
| |
| fn nested_visit_map(&mut self) -> hir_visit::NestedVisitorMap<Self::Map> { |
| hir_visit::NestedVisitorMap::OnlyBodies(self.tcx.hir()) |
| } |
| |
| #[instrument(skip(self, i), level = "debug")] |
| fn visit_item(&mut self, i: &'tcx hir::Item<'tcx>) { |
| trace!(?i); |
| self.tcx.ensure().check_item_well_formed(i.def_id); |
| hir_visit::walk_item(self, i); |
| } |
| |
| #[instrument(skip(self, trait_item), level = "debug")] |
| fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) { |
| trace!(?trait_item); |
| self.tcx.ensure().check_trait_item_well_formed(trait_item.def_id); |
| hir_visit::walk_trait_item(self, trait_item); |
| } |
| |
| #[instrument(skip(self, impl_item), level = "debug")] |
| fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { |
| trace!(?impl_item); |
| self.tcx.ensure().check_impl_item_well_formed(impl_item.def_id); |
| hir_visit::walk_impl_item(self, impl_item); |
| } |
| |
| fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) { |
| check_param_wf(self.tcx, p); |
| hir_visit::walk_generic_param(self, p); |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // ADT |
| |
| // FIXME(eddyb) replace this with getting fields/discriminants through `ty::AdtDef`. |
| struct AdtVariant<'tcx> { |
| /// Types of fields in the variant, that must be well-formed. |
| fields: Vec<AdtField<'tcx>>, |
| |
| /// Explicit discriminant of this variant (e.g. `A = 123`), |
| /// that must evaluate to a constant value. |
| explicit_discr: Option<LocalDefId>, |
| } |
| |
| struct AdtField<'tcx> { |
| ty: Ty<'tcx>, |
| def_id: LocalDefId, |
| span: Span, |
| } |
| |
| impl<'a, 'tcx> FnCtxt<'a, 'tcx> { |
| // FIXME(eddyb) replace this with getting fields through `ty::AdtDef`. |
| fn non_enum_variant(&self, struct_def: &hir::VariantData<'_>) -> AdtVariant<'tcx> { |
| let fields = struct_def |
| .fields() |
| .iter() |
| .map(|field| { |
| let def_id = self.tcx.hir().local_def_id(field.hir_id); |
| let field_ty = self.tcx.type_of(def_id); |
| let field_ty = self.normalize_associated_types_in(field.ty.span, field_ty); |
| let field_ty = self.resolve_vars_if_possible(field_ty); |
| debug!("non_enum_variant: type of field {:?} is {:?}", field, field_ty); |
| AdtField { ty: field_ty, span: field.ty.span, def_id } |
| }) |
| .collect(); |
| AdtVariant { fields, explicit_discr: None } |
| } |
| |
| fn enum_variants(&self, enum_def: &hir::EnumDef<'_>) -> Vec<AdtVariant<'tcx>> { |
| enum_def |
| .variants |
| .iter() |
| .map(|variant| AdtVariant { |
| fields: self.non_enum_variant(&variant.data).fields, |
| explicit_discr: variant |
| .disr_expr |
| .map(|explicit_discr| self.tcx.hir().local_def_id(explicit_discr.hir_id)), |
| }) |
| .collect() |
| } |
| |
| pub(super) fn impl_implied_bounds( |
| &self, |
| impl_def_id: DefId, |
| span: Span, |
| ) -> FxHashSet<Ty<'tcx>> { |
| match self.tcx.impl_trait_ref(impl_def_id) { |
| Some(trait_ref) => { |
| // Trait impl: take implied bounds from all types that |
| // appear in the trait reference. |
| let trait_ref = self.normalize_associated_types_in(span, trait_ref); |
| trait_ref.substs.types().collect() |
| } |
| |
| None => { |
| // Inherent impl: take implied bounds from the `self` type. |
| let self_ty = self.tcx.type_of(impl_def_id); |
| let self_ty = self.normalize_associated_types_in(span, self_ty); |
| std::array::IntoIter::new([self_ty]).collect() |
| } |
| } |
| } |
| } |
| |
| fn error_392(tcx: TyCtxt<'_>, span: Span, param_name: Symbol) -> DiagnosticBuilder<'_> { |
| let mut err = |
| struct_span_err!(tcx.sess, span, E0392, "parameter `{}` is never used", param_name); |
| err.span_label(span, "unused parameter"); |
| err |
| } |
