| use rustc::hir::{self, GenericParamKind, ImplItemKind, TraitItemKind}; |
| use rustc::hir::def::{Res, DefKind}; |
| use rustc::infer::{self, InferOk}; |
| use rustc::ty::{self, TyCtxt, GenericParamDefKind}; |
| use rustc::ty::util::ExplicitSelf; |
| use rustc::traits::{self, ObligationCause, ObligationCauseCode, Reveal}; |
| use rustc::ty::error::{ExpectedFound, TypeError}; |
| use rustc::ty::subst::{Subst, InternalSubsts, SubstsRef}; |
| use rustc::util::common::ErrorReported; |
| use errors::{Applicability, DiagnosticId}; |
| |
| use syntax_pos::Span; |
| use syntax::errors::pluralize; |
| |
| use super::{Inherited, FnCtxt, potentially_plural_count}; |
| |
| use rustc_error_codes::*; |
| |
| /// Checks that a method from an impl conforms to the signature of |
| /// the same method as declared in the trait. |
| /// |
| /// # Parameters |
| /// |
| /// - `impl_m`: type of the method we are checking |
| /// - `impl_m_span`: span to use for reporting errors |
| /// - `trait_m`: the method in the trait |
| /// - `impl_trait_ref`: the TraitRef corresponding to the trait implementation |
| |
| pub fn compare_impl_method<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| impl_m_span: Span, |
| trait_m: &ty::AssocItem, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| trait_item_span: Option<Span>, |
| ) { |
| debug!("compare_impl_method(impl_trait_ref={:?})", |
| impl_trait_ref); |
| |
| let impl_m_span = tcx.sess.source_map().def_span(impl_m_span); |
| |
| if let Err(ErrorReported) = compare_self_type(tcx, |
| impl_m, |
| impl_m_span, |
| trait_m, |
| impl_trait_ref) { |
| return; |
| } |
| |
| if let Err(ErrorReported) = compare_number_of_generics(tcx, |
| impl_m, |
| impl_m_span, |
| trait_m, |
| trait_item_span) { |
| return; |
| } |
| |
| if let Err(ErrorReported) = compare_number_of_method_arguments(tcx, |
| impl_m, |
| impl_m_span, |
| trait_m, |
| trait_item_span) { |
| return; |
| } |
| |
| if let Err(ErrorReported) = compare_synthetic_generics(tcx, |
| impl_m, |
| trait_m) { |
| return; |
| } |
| |
| if let Err(ErrorReported) = compare_predicate_entailment(tcx, |
| impl_m, |
| impl_m_span, |
| trait_m, |
| impl_trait_ref) { |
| return; |
| } |
| } |
| |
| fn compare_predicate_entailment<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| impl_m_span: Span, |
| trait_m: &ty::AssocItem, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| ) -> Result<(), ErrorReported> { |
| let trait_to_impl_substs = impl_trait_ref.substs; |
| |
| // This node-id should be used for the `body_id` field on each |
| // `ObligationCause` (and the `FnCtxt`). This is what |
| // `regionck_item` expects. |
| let impl_m_hir_id = tcx.hir().as_local_hir_id(impl_m.def_id).unwrap(); |
| |
| let cause = ObligationCause { |
| span: impl_m_span, |
| body_id: impl_m_hir_id, |
| code: ObligationCauseCode::CompareImplMethodObligation { |
| item_name: impl_m.ident.name, |
| impl_item_def_id: impl_m.def_id, |
| trait_item_def_id: trait_m.def_id, |
| }, |
| }; |
| |
| // This code is best explained by example. Consider a trait: |
| // |
| // trait Trait<'t,T> { |
| // fn method<'a,M>(t: &'t T, m: &'a M) -> Self; |
| // } |
| // |
| // And an impl: |
| // |
| // impl<'i, 'j, U> Trait<'j, &'i U> for Foo { |
| // fn method<'b,N>(t: &'j &'i U, m: &'b N) -> Foo; |
| // } |
| // |
| // We wish to decide if those two method types are compatible. |
| // |
| // We start out with trait_to_impl_substs, that maps the trait |
| // type parameters to impl type parameters. This is taken from the |
| // impl trait reference: |
| // |
| // trait_to_impl_substs = {'t => 'j, T => &'i U, Self => Foo} |
| // |
| // We create a mapping `dummy_substs` that maps from the impl type |
| // parameters to fresh types and regions. For type parameters, |
| // this is the identity transform, but we could as well use any |
| // placeholder types. For regions, we convert from bound to free |
| // regions (Note: but only early-bound regions, i.e., those |
| // declared on the impl or used in type parameter bounds). |
| // |
| // impl_to_skol_substs = {'i => 'i0, U => U0, N => N0 } |
| // |
| // Now we can apply skol_substs to the type of the impl method |
| // to yield a new function type in terms of our fresh, placeholder |
| // types: |
| // |
| // <'b> fn(t: &'i0 U0, m: &'b) -> Foo |
| // |
| // We now want to extract and substitute the type of the *trait* |
| // method and compare it. To do so, we must create a compound |
| // substitution by combining trait_to_impl_substs and |
| // impl_to_skol_substs, and also adding a mapping for the method |
| // type parameters. We extend the mapping to also include |
| // the method parameters. |
| // |
| // trait_to_skol_substs = { T => &'i0 U0, Self => Foo, M => N0 } |
| // |
| // Applying this to the trait method type yields: |
| // |
| // <'a> fn(t: &'i0 U0, m: &'a) -> Foo |
| // |
| // This type is also the same but the name of the bound region ('a |
| // vs 'b). However, the normal subtyping rules on fn types handle |
| // this kind of equivalency just fine. |
| // |
| // We now use these substitutions to ensure that all declared bounds are |
| // satisfied by the implementation's method. |
| // |
| // We do this by creating a parameter environment which contains a |
| // substitution corresponding to impl_to_skol_substs. We then build |
| // trait_to_skol_substs and use it to convert the predicates contained |
| // in the trait_m.generics to the placeholder form. |
| // |
| // Finally we register each of these predicates as an obligation in |
| // a fresh FulfillmentCtxt, and invoke select_all_or_error. |
| |
| // Create mapping from impl to placeholder. |
| let impl_to_skol_substs = InternalSubsts::identity_for_item(tcx, impl_m.def_id); |
| |
| // Create mapping from trait to placeholder. |
| let trait_to_skol_substs = impl_to_skol_substs.rebase_onto(tcx, |
| impl_m.container.id(), |
| trait_to_impl_substs); |
| debug!("compare_impl_method: trait_to_skol_substs={:?}", |
| trait_to_skol_substs); |
| |
| let impl_m_generics = tcx.generics_of(impl_m.def_id); |
| let trait_m_generics = tcx.generics_of(trait_m.def_id); |
| let impl_m_predicates = tcx.predicates_of(impl_m.def_id); |
| let trait_m_predicates = tcx.predicates_of(trait_m.def_id); |
| |
| // Check region bounds. |
| check_region_bounds_on_impl_method(tcx, |
| impl_m_span, |
| impl_m, |
| trait_m, |
| &trait_m_generics, |
| &impl_m_generics, |
| trait_to_skol_substs)?; |
| |
| // Create obligations for each predicate declared by the impl |
| // definition in the context of the trait's parameter |
| // environment. We can't just use `impl_env.caller_bounds`, |
| // however, because we want to replace all late-bound regions with |
| // region variables. |
| let impl_predicates = tcx.predicates_of(impl_m_predicates.parent.unwrap()); |
| let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); |
| |
| debug!("compare_impl_method: impl_bounds={:?}", hybrid_preds); |
| |
| // This is the only tricky bit of the new way we check implementation methods |
| // We need to build a set of predicates where only the method-level bounds |
| // are from the trait and we assume all other bounds from the implementation |
| // to be previously satisfied. |
| // |
| // We then register the obligations from the impl_m and check to see |
| // if all constraints hold. |
| hybrid_preds.predicates.extend( |
| trait_m_predicates.instantiate_own(tcx, trait_to_skol_substs).predicates); |
| |
| // Construct trait parameter environment and then shift it into the placeholder viewpoint. |
| // The key step here is to update the caller_bounds's predicates to be |
| // the new hybrid bounds we computed. |
| let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_hir_id); |
| let param_env = ty::ParamEnv::new( |
| tcx.intern_predicates(&hybrid_preds.predicates), |
| Reveal::UserFacing, |
| None |
| ); |
| let param_env = traits::normalize_param_env_or_error(tcx, |
| impl_m.def_id, |
| param_env, |
| normalize_cause.clone()); |
| |
| tcx.infer_ctxt().enter(|infcx| { |
| let inh = Inherited::new(infcx, impl_m.def_id); |
| let infcx = &inh.infcx; |
| |
| debug!("compare_impl_method: caller_bounds={:?}", |
| param_env.caller_bounds); |
| |
| let mut selcx = traits::SelectionContext::new(&infcx); |
| |
| let impl_m_own_bounds = impl_m_predicates.instantiate_own(tcx, impl_to_skol_substs); |
| let (impl_m_own_bounds, _) = infcx.replace_bound_vars_with_fresh_vars( |
| impl_m_span, |
| infer::HigherRankedType, |
| &ty::Binder::bind(impl_m_own_bounds.predicates) |
| ); |
| for predicate in impl_m_own_bounds { |
| let traits::Normalized { value: predicate, obligations } = |
| traits::normalize(&mut selcx, param_env, normalize_cause.clone(), &predicate); |
| |
| inh.register_predicates(obligations); |
| inh.register_predicate(traits::Obligation::new(cause.clone(), param_env, predicate)); |
| } |
| |
| // We now need to check that the signature of the impl method is |
| // compatible with that of the trait method. We do this by |
| // checking that `impl_fty <: trait_fty`. |
| // |
| // FIXME. Unfortunately, this doesn't quite work right now because |
| // associated type normalization is not integrated into subtype |
| // checks. For the comparison to be valid, we need to |
| // normalize the associated types in the impl/trait methods |
| // first. However, because function types bind regions, just |
| // calling `normalize_associated_types_in` would have no effect on |
| // any associated types appearing in the fn arguments or return |
| // type. |
| |
| // Compute placeholder form of impl and trait method tys. |
| let tcx = infcx.tcx; |
| |
| let (impl_sig, _) = infcx.replace_bound_vars_with_fresh_vars( |
| impl_m_span, |
| infer::HigherRankedType, |
| &tcx.fn_sig(impl_m.def_id) |
| ); |
| let impl_sig = |
| inh.normalize_associated_types_in(impl_m_span, |
| impl_m_hir_id, |
| param_env, |
| &impl_sig); |
| let impl_fty = tcx.mk_fn_ptr(ty::Binder::bind(impl_sig)); |
| debug!("compare_impl_method: impl_fty={:?}", impl_fty); |
| |
| let trait_sig = tcx.liberate_late_bound_regions( |
| impl_m.def_id, |
| &tcx.fn_sig(trait_m.def_id)); |
| let trait_sig = |
| trait_sig.subst(tcx, trait_to_skol_substs); |
| let trait_sig = |
| inh.normalize_associated_types_in(impl_m_span, |
| impl_m_hir_id, |
| param_env, |
| &trait_sig); |
| let trait_fty = tcx.mk_fn_ptr(ty::Binder::bind(trait_sig)); |
| |
| debug!("compare_impl_method: trait_fty={:?}", trait_fty); |
| |
| let sub_result = infcx.at(&cause, param_env) |
| .sup(trait_fty, impl_fty) |
| .map(|InferOk { obligations, .. }| { |
| inh.register_predicates(obligations); |
| }); |
| |
| if let Err(terr) = sub_result { |
| debug!("sub_types failed: impl ty {:?}, trait ty {:?}", |
| impl_fty, |
| trait_fty); |
| |
| let (impl_err_span, trait_err_span) = extract_spans_for_error_reporting(&infcx, |
| param_env, |
| &terr, |
| &cause, |
| impl_m, |
| impl_sig, |
| trait_m, |
| trait_sig); |
| |
| let cause = ObligationCause { |
| span: impl_err_span, |
| ..cause |
| }; |
| |
| let mut diag = struct_span_err!(tcx.sess, |
| cause.span(tcx), |
| E0053, |
| "method `{}` has an incompatible type for trait", |
| trait_m.ident); |
| if let TypeError::Mutability = terr { |
| if let Some(trait_err_span) = trait_err_span { |
| if let Ok(trait_err_str) = tcx.sess.source_map() |
| .span_to_snippet(trait_err_span) { |
| diag.span_suggestion( |
| impl_err_span, |
| "consider change the type to match the mutability in trait", |
| trait_err_str, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| |
| infcx.note_type_err(&mut diag, |
| &cause, |
| trait_err_span.map(|sp| (sp, "type in trait".to_owned())), |
| Some(infer::ValuePairs::Types(ExpectedFound { |
| expected: trait_fty, |
| found: impl_fty, |
| })), |
| &terr); |
| diag.emit(); |
| return Err(ErrorReported); |
| } |
| |
| // Check that all obligations are satisfied by the implementation's |
| // version. |
| if let Err(ref errors) = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx) { |
| infcx.report_fulfillment_errors(errors, None, false); |
| return Err(ErrorReported); |
| } |
| |
| // Finally, resolve all regions. This catches wily misuses of |
| // lifetime parameters. |
| let fcx = FnCtxt::new(&inh, param_env, impl_m_hir_id); |
| fcx.regionck_item(impl_m_hir_id, impl_m_span, &[]); |
| |
| Ok(()) |
| }) |
| } |
| |
| fn check_region_bounds_on_impl_method<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| span: Span, |
| impl_m: &ty::AssocItem, |
| trait_m: &ty::AssocItem, |
| trait_generics: &ty::Generics, |
| impl_generics: &ty::Generics, |
| trait_to_skol_substs: SubstsRef<'tcx>, |
| ) -> Result<(), ErrorReported> { |
| let trait_params = trait_generics.own_counts().lifetimes; |
| let impl_params = impl_generics.own_counts().lifetimes; |
| |
| debug!("check_region_bounds_on_impl_method: \ |
| trait_generics={:?} \ |
| impl_generics={:?} \ |
| trait_to_skol_substs={:?}", |
| trait_generics, |
| impl_generics, |
| trait_to_skol_substs); |
| |
| // Must have same number of early-bound lifetime parameters. |
| // Unfortunately, if the user screws up the bounds, then this |
| // will change classification between early and late. E.g., |
| // if in trait we have `<'a,'b:'a>`, and in impl we just have |
| // `<'a,'b>`, then we have 2 early-bound lifetime parameters |
| // in trait but 0 in the impl. But if we report "expected 2 |
| // but found 0" it's confusing, because it looks like there |
| // are zero. Since I don't quite know how to phrase things at |
| // the moment, give a kind of vague error message. |
| if trait_params != impl_params { |
| let def_span = tcx.sess.source_map().def_span(span); |
| let span = tcx.hir().get_generics(impl_m.def_id).map(|g| g.span).unwrap_or(def_span); |
| let mut err = struct_span_err!( |
| tcx.sess, |
| span, |
| E0195, |
| "lifetime parameters or bounds on method `{}` do not match the trait declaration", |
| impl_m.ident, |
| ); |
| err.span_label(span, "lifetimes do not match method in trait"); |
| if let Some(sp) = tcx.hir().span_if_local(trait_m.def_id) { |
| let def_sp = tcx.sess.source_map().def_span(sp); |
| let sp = tcx.hir().get_generics(trait_m.def_id).map(|g| g.span).unwrap_or(def_sp); |
| err.span_label(sp, "lifetimes in impl do not match this method in trait"); |
| } |
| err.emit(); |
| return Err(ErrorReported); |
| } |
| |
| Ok(()) |
| } |
| |
| fn extract_spans_for_error_reporting<'a, 'tcx>( |
| infcx: &infer::InferCtxt<'a, 'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| terr: &TypeError<'_>, |
| cause: &ObligationCause<'tcx>, |
| impl_m: &ty::AssocItem, |
| impl_sig: ty::FnSig<'tcx>, |
| trait_m: &ty::AssocItem, |
| trait_sig: ty::FnSig<'tcx>, |
| ) -> (Span, Option<Span>) { |
| let tcx = infcx.tcx; |
| let impl_m_hir_id = tcx.hir().as_local_hir_id(impl_m.def_id).unwrap(); |
| let (impl_m_output, impl_m_iter) = match tcx.hir() |
| .expect_impl_item(impl_m_hir_id) |
| .kind { |
| ImplItemKind::Method(ref impl_m_sig, _) => { |
| (&impl_m_sig.decl.output, impl_m_sig.decl.inputs.iter()) |
| } |
| _ => bug!("{:?} is not a method", impl_m), |
| }; |
| |
| match *terr { |
| TypeError::Mutability => { |
| if let Some(trait_m_hir_id) = tcx.hir().as_local_hir_id(trait_m.def_id) { |
| let trait_m_iter = match tcx.hir() |
| .expect_trait_item(trait_m_hir_id) |
| .kind { |
| TraitItemKind::Method(ref trait_m_sig, _) => { |
| trait_m_sig.decl.inputs.iter() |
| } |
| _ => bug!("{:?} is not a TraitItemKind::Method", trait_m), |
| }; |
| |
| impl_m_iter.zip(trait_m_iter).find(|&(ref impl_arg, ref trait_arg)| { |
| match (&impl_arg.kind, &trait_arg.kind) { |
| (&hir::TyKind::Rptr(_, ref impl_mt), &hir::TyKind::Rptr(_, ref trait_mt)) | |
| (&hir::TyKind::Ptr(ref impl_mt), &hir::TyKind::Ptr(ref trait_mt)) => { |
| impl_mt.mutbl != trait_mt.mutbl |
| } |
| _ => false, |
| } |
| }).map(|(ref impl_arg, ref trait_arg)| { |
| (impl_arg.span, Some(trait_arg.span)) |
| }) |
| .unwrap_or_else(|| (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id))) |
| } else { |
| (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)) |
| } |
| } |
| TypeError::Sorts(ExpectedFound { .. }) => { |
| if let Some(trait_m_hir_id) = tcx.hir().as_local_hir_id(trait_m.def_id) { |
| let (trait_m_output, trait_m_iter) = |
| match tcx.hir().expect_trait_item(trait_m_hir_id).kind { |
| TraitItemKind::Method(ref trait_m_sig, _) => { |
| (&trait_m_sig.decl.output, trait_m_sig.decl.inputs.iter()) |
| } |
| _ => bug!("{:?} is not a TraitItemKind::Method", trait_m), |
| }; |
| |
| let impl_iter = impl_sig.inputs().iter(); |
| let trait_iter = trait_sig.inputs().iter(); |
| impl_iter.zip(trait_iter) |
| .zip(impl_m_iter) |
| .zip(trait_m_iter) |
| .filter_map(|(((&impl_arg_ty, &trait_arg_ty), impl_arg), trait_arg)| |
| match infcx.at(&cause, param_env).sub(trait_arg_ty, impl_arg_ty) { |
| Ok(_) => None, |
| Err(_) => Some((impl_arg.span, Some(trait_arg.span))), |
| } |
| ) |
| .next() |
| .unwrap_or_else(|| |
| if |
| infcx.at(&cause, param_env) |
| .sup(trait_sig.output(), impl_sig.output()) |
| .is_err() |
| { |
| (impl_m_output.span(), Some(trait_m_output.span())) |
| } else { |
| (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)) |
| } |
| ) |
| } else { |
| (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)) |
| } |
| } |
| _ => (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)), |
| } |
| } |
| |
| fn compare_self_type<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| impl_m_span: Span, |
| trait_m: &ty::AssocItem, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| ) -> Result<(), ErrorReported> { |
| // Try to give more informative error messages about self typing |
| // mismatches. Note that any mismatch will also be detected |
| // below, where we construct a canonical function type that |
| // includes the self parameter as a normal parameter. It's just |
| // that the error messages you get out of this code are a bit more |
| // inscrutable, particularly for cases where one method has no |
| // self. |
| |
| let self_string = |method: &ty::AssocItem| { |
| let untransformed_self_ty = match method.container { |
| ty::ImplContainer(_) => impl_trait_ref.self_ty(), |
| ty::TraitContainer(_) => tcx.types.self_param |
| }; |
| let self_arg_ty = *tcx.fn_sig(method.def_id).input(0).skip_binder(); |
| let param_env = ty::ParamEnv::reveal_all(); |
| |
| tcx.infer_ctxt().enter(|infcx| { |
| let self_arg_ty = tcx.liberate_late_bound_regions( |
| method.def_id, |
| &ty::Binder::bind(self_arg_ty) |
| ); |
| let can_eq_self = |ty| infcx.can_eq(param_env, untransformed_self_ty, ty).is_ok(); |
| match ExplicitSelf::determine(self_arg_ty, can_eq_self) { |
| ExplicitSelf::ByValue => "self".to_owned(), |
| ExplicitSelf::ByReference(_, hir::Mutability::Immutable) => "&self".to_owned(), |
| ExplicitSelf::ByReference(_, hir::Mutability::Mutable) => "&mut self".to_owned(), |
| _ => format!("self: {}", self_arg_ty) |
| } |
| }) |
| }; |
| |
| match (trait_m.method_has_self_argument, impl_m.method_has_self_argument) { |
| (false, false) | (true, true) => {} |
| |
| (false, true) => { |
| let self_descr = self_string(impl_m); |
| let mut err = struct_span_err!(tcx.sess, |
| impl_m_span, |
| E0185, |
| "method `{}` has a `{}` declaration in the impl, but \ |
| not in the trait", |
| trait_m.ident, |
| self_descr); |
| err.span_label(impl_m_span, format!("`{}` used in impl", self_descr)); |
| if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
| err.span_label(span, format!("trait method declared without `{}`", self_descr)); |
| } else { |
| err.note_trait_signature(trait_m.ident.to_string(), |
| trait_m.signature(tcx)); |
| } |
| err.emit(); |
| return Err(ErrorReported); |
| } |
| |
| (true, false) => { |
| let self_descr = self_string(trait_m); |
| let mut err = struct_span_err!(tcx.sess, |
| impl_m_span, |
| E0186, |
| "method `{}` has a `{}` declaration in the trait, but \ |
| not in the impl", |
| trait_m.ident, |
| self_descr); |
| err.span_label(impl_m_span, format!("expected `{}` in impl", self_descr)); |
| if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
| err.span_label(span, format!("`{}` used in trait", self_descr)); |
| } else { |
| err.note_trait_signature(trait_m.ident.to_string(), |
| trait_m.signature(tcx)); |
| } |
| err.emit(); |
| return Err(ErrorReported); |
| } |
| } |
| |
| Ok(()) |
| } |
| |
| fn compare_number_of_generics<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_: &ty::AssocItem, |
| _impl_span: Span, |
| trait_: &ty::AssocItem, |
| trait_span: Option<Span>, |
| ) -> Result<(), ErrorReported> { |
| let trait_own_counts = tcx.generics_of(trait_.def_id).own_counts(); |
| let impl_own_counts = tcx.generics_of(impl_.def_id).own_counts(); |
| |
| let matchings = [ |
| ("type", trait_own_counts.types, impl_own_counts.types), |
| ("const", trait_own_counts.consts, impl_own_counts.consts), |
| ]; |
| |
| let mut err_occurred = false; |
| for &(kind, trait_count, impl_count) in &matchings { |
| if impl_count != trait_count { |
| err_occurred = true; |
| |
| let ( |
| trait_spans, |
| impl_trait_spans, |
| ) = if let Some(trait_hir_id) = tcx.hir().as_local_hir_id(trait_.def_id) { |
| let trait_item = tcx.hir().expect_trait_item(trait_hir_id); |
| if trait_item.generics.params.is_empty() { |
| (Some(vec![trait_item.generics.span]), vec![]) |
| } else { |
| let arg_spans: Vec<Span> = trait_item.generics.params.iter() |
| .map(|p| p.span) |
| .collect(); |
| let impl_trait_spans: Vec<Span> = trait_item.generics.params.iter() |
| .filter_map(|p| match p.kind { |
| GenericParamKind::Type { |
| synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), .. |
| } => Some(p.span), |
| _ => None, |
| }).collect(); |
| (Some(arg_spans), impl_trait_spans) |
| } |
| } else { |
| (trait_span.map(|s| vec![s]), vec![]) |
| }; |
| |
| let impl_hir_id = tcx.hir().as_local_hir_id(impl_.def_id).unwrap(); |
| let impl_item = tcx.hir().expect_impl_item(impl_hir_id); |
| let impl_item_impl_trait_spans: Vec<Span> = impl_item.generics.params.iter() |
| .filter_map(|p| match p.kind { |
| GenericParamKind::Type { |
| synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), .. |
| } => Some(p.span), |
| _ => None, |
| }).collect(); |
| let spans = impl_item.generics.spans(); |
| let span = spans.primary_span(); |
| |
| let mut err = tcx.sess.struct_span_err_with_code( |
| spans, |
| &format!( |
| "method `{}` has {} {kind} parameter{} but its trait \ |
| declaration has {} {kind} parameter{}", |
| trait_.ident, |
| impl_count, |
| pluralize!(impl_count), |
| trait_count, |
| pluralize!(trait_count), |
| kind = kind, |
| ), |
| DiagnosticId::Error("E0049".into()), |
| ); |
| |
| let mut suffix = None; |
| |
| if let Some(spans) = trait_spans { |
| let mut spans = spans.iter(); |
| if let Some(span) = spans.next() { |
| err.span_label(*span, format!( |
| "expected {} {} parameter{}", |
| trait_count, |
| kind, |
| pluralize!(trait_count), |
| )); |
| } |
| for span in spans { |
| err.span_label(*span, ""); |
| } |
| } else { |
| suffix = Some(format!(", expected {}", trait_count)); |
| } |
| |
| if let Some(span) = span { |
| err.span_label(span, format!( |
| "found {} {} parameter{}{}", |
| impl_count, |
| kind, |
| pluralize!(impl_count), |
| suffix.unwrap_or_else(|| String::new()), |
| )); |
| } |
| |
| for span in impl_trait_spans.iter().chain(impl_item_impl_trait_spans.iter()) { |
| err.span_label(*span, "`impl Trait` introduces an implicit type parameter"); |
| } |
| |
| err.emit(); |
| } |
| } |
| |
| if err_occurred { |
| Err(ErrorReported) |
| } else { |
| Ok(()) |
| } |
| } |
| |
| fn compare_number_of_method_arguments<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| impl_m_span: Span, |
| trait_m: &ty::AssocItem, |
| trait_item_span: Option<Span>, |
| ) -> Result<(), ErrorReported> { |
| let impl_m_fty = tcx.fn_sig(impl_m.def_id); |
| let trait_m_fty = tcx.fn_sig(trait_m.def_id); |
| let trait_number_args = trait_m_fty.inputs().skip_binder().len(); |
| let impl_number_args = impl_m_fty.inputs().skip_binder().len(); |
| if trait_number_args != impl_number_args { |
| let trait_m_hir_id = tcx.hir().as_local_hir_id(trait_m.def_id); |
| let trait_span = if let Some(trait_id) = trait_m_hir_id { |
| match tcx.hir().expect_trait_item(trait_id).kind { |
| TraitItemKind::Method(ref trait_m_sig, _) => { |
| let pos = if trait_number_args > 0 { |
| trait_number_args - 1 |
| } else { |
| 0 |
| }; |
| if let Some(arg) = trait_m_sig.decl.inputs.get(pos) { |
| Some(if pos == 0 { |
| arg.span |
| } else { |
| Span::new(trait_m_sig.decl.inputs[0].span.lo(), |
| arg.span.hi(), |
| arg.span.ctxt()) |
| }) |
| } else { |
| trait_item_span |
| } |
| } |
| _ => bug!("{:?} is not a method", impl_m), |
| } |
| } else { |
| trait_item_span |
| }; |
| let impl_m_hir_id = tcx.hir().as_local_hir_id(impl_m.def_id).unwrap(); |
| let impl_span = match tcx.hir().expect_impl_item(impl_m_hir_id).kind { |
| ImplItemKind::Method(ref impl_m_sig, _) => { |
| let pos = if impl_number_args > 0 { |
| impl_number_args - 1 |
| } else { |
| 0 |
| }; |
| if let Some(arg) = impl_m_sig.decl.inputs.get(pos) { |
| if pos == 0 { |
| arg.span |
| } else { |
| Span::new(impl_m_sig.decl.inputs[0].span.lo(), |
| arg.span.hi(), |
| arg.span.ctxt()) |
| } |
| } else { |
| impl_m_span |
| } |
| } |
| _ => bug!("{:?} is not a method", impl_m), |
| }; |
| let mut err = struct_span_err!(tcx.sess, |
| impl_span, |
| E0050, |
| "method `{}` has {} but the declaration in \ |
| trait `{}` has {}", |
| trait_m.ident, |
| potentially_plural_count(impl_number_args, "parameter"), |
| tcx.def_path_str(trait_m.def_id), |
| trait_number_args); |
| if let Some(trait_span) = trait_span { |
| err.span_label(trait_span, format!("trait requires {}", |
| potentially_plural_count(trait_number_args, "parameter"))); |
| } else { |
| err.note_trait_signature(trait_m.ident.to_string(), |
| trait_m.signature(tcx)); |
| } |
| err.span_label(impl_span, format!("expected {}, found {}", |
| potentially_plural_count(trait_number_args, "parameter"), impl_number_args)); |
| err.emit(); |
| return Err(ErrorReported); |
| } |
| |
| Ok(()) |
| } |
| |
| fn compare_synthetic_generics<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| trait_m: &ty::AssocItem, |
| ) -> Result<(), ErrorReported> { |
| // FIXME(chrisvittal) Clean up this function, list of FIXME items: |
| // 1. Better messages for the span labels |
| // 2. Explanation as to what is going on |
| // If we get here, we already have the same number of generics, so the zip will |
| // be okay. |
| let mut error_found = false; |
| let impl_m_generics = tcx.generics_of(impl_m.def_id); |
| let trait_m_generics = tcx.generics_of(trait_m.def_id); |
| let impl_m_type_params = impl_m_generics.params.iter().filter_map(|param| match param.kind { |
| GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), |
| GenericParamDefKind::Lifetime | GenericParamDefKind::Const => None, |
| }); |
| let trait_m_type_params = trait_m_generics.params.iter().filter_map(|param| { |
| match param.kind { |
| GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), |
| GenericParamDefKind::Lifetime | GenericParamDefKind::Const => None, |
| } |
| }); |
| for ((impl_def_id, impl_synthetic), (trait_def_id, trait_synthetic)) |
| in impl_m_type_params.zip(trait_m_type_params) |
| { |
| if impl_synthetic != trait_synthetic { |
| let impl_hir_id = tcx.hir().as_local_hir_id(impl_def_id).unwrap(); |
| let impl_span = tcx.hir().span(impl_hir_id); |
| let trait_span = tcx.def_span(trait_def_id); |
| let mut err = struct_span_err!(tcx.sess, |
| impl_span, |
| E0643, |
| "method `{}` has incompatible signature for trait", |
| trait_m.ident); |
| err.span_label(trait_span, "declaration in trait here"); |
| match (impl_synthetic, trait_synthetic) { |
| // The case where the impl method uses `impl Trait` but the trait method uses |
| // explicit generics |
| (Some(hir::SyntheticTyParamKind::ImplTrait), None) => { |
| err.span_label(impl_span, "expected generic parameter, found `impl Trait`"); |
| (|| { |
| // try taking the name from the trait impl |
| // FIXME: this is obviously suboptimal since the name can already be used |
| // as another generic argument |
| let new_name = tcx |
| .sess |
| .source_map() |
| .span_to_snippet(trait_span) |
| .ok()?; |
| let trait_m = tcx.hir().as_local_hir_id(trait_m.def_id)?; |
| let trait_m = tcx.hir().trait_item(hir::TraitItemId { hir_id: trait_m }); |
| |
| let impl_m = tcx.hir().as_local_hir_id(impl_m.def_id)?; |
| let impl_m = tcx.hir().impl_item(hir::ImplItemId { hir_id: impl_m }); |
| |
| // in case there are no generics, take the spot between the function name |
| // and the opening paren of the argument list |
| let new_generics_span = tcx |
| .sess |
| .source_map() |
| .generate_fn_name_span(impl_span)? |
| .shrink_to_hi(); |
| // in case there are generics, just replace them |
| let generics_span = impl_m |
| .generics |
| .span |
| .substitute_dummy(new_generics_span); |
| // replace with the generics from the trait |
| let new_generics = tcx |
| .sess |
| .source_map() |
| .span_to_snippet(trait_m.generics.span) |
| .ok()?; |
| |
| err.multipart_suggestion( |
| "try changing the `impl Trait` argument to a generic parameter", |
| vec![ |
| // replace `impl Trait` with `T` |
| (impl_span, new_name), |
| // replace impl method generics with trait method generics |
| // This isn't quite right, as users might have changed the names |
| // of the generics, but it works for the common case |
| (generics_span, new_generics), |
| ], |
| Applicability::MaybeIncorrect, |
| ); |
| Some(()) |
| })(); |
| }, |
| // The case where the trait method uses `impl Trait`, but the impl method uses |
| // explicit generics. |
| (None, Some(hir::SyntheticTyParamKind::ImplTrait)) => { |
| err.span_label(impl_span, "expected `impl Trait`, found generic parameter"); |
| (|| { |
| let impl_m = tcx.hir().as_local_hir_id(impl_m.def_id)?; |
| let impl_m = tcx.hir().impl_item(hir::ImplItemId { hir_id: impl_m }); |
| let input_tys = match impl_m.kind { |
| hir::ImplItemKind::Method(ref sig, _) => &sig.decl.inputs, |
| _ => unreachable!(), |
| }; |
| struct Visitor(Option<Span>, hir::def_id::DefId); |
| impl<'v> hir::intravisit::Visitor<'v> for Visitor { |
| fn visit_ty(&mut self, ty: &'v hir::Ty) { |
| hir::intravisit::walk_ty(self, ty); |
| if let hir::TyKind::Path( |
| hir::QPath::Resolved(None, ref path)) = ty.kind |
| { |
| if let Res::Def(DefKind::TyParam, def_id) = path.res { |
| if def_id == self.1 { |
| self.0 = Some(ty.span); |
| } |
| } |
| } |
| } |
| fn nested_visit_map<'this>( |
| &'this mut self |
| ) -> hir::intravisit::NestedVisitorMap<'this, 'v> { |
| hir::intravisit::NestedVisitorMap::None |
| } |
| } |
| let mut visitor = Visitor(None, impl_def_id); |
| for ty in input_tys { |
| hir::intravisit::Visitor::visit_ty(&mut visitor, ty); |
| } |
| let span = visitor.0?; |
| |
| let bounds = impl_m.generics.params.iter().find_map(|param| { |
| match param.kind { |
| GenericParamKind::Lifetime { .. } => None, |
| GenericParamKind::Type { .. } | |
| GenericParamKind::Const { .. } => { |
| if param.hir_id == impl_hir_id { |
| Some(¶m.bounds) |
| } else { |
| None |
| } |
| } |
| } |
| })?; |
| let bounds = bounds.first()?.span().to(bounds.last()?.span()); |
| let bounds = tcx |
| .sess |
| .source_map() |
| .span_to_snippet(bounds) |
| .ok()?; |
| |
| err.multipart_suggestion( |
| "try removing the generic parameter and using `impl Trait` instead", |
| vec![ |
| // delete generic parameters |
| (impl_m.generics.span, String::new()), |
| // replace param usage with `impl Trait` |
| (span, format!("impl {}", bounds)), |
| ], |
| Applicability::MaybeIncorrect, |
| ); |
| Some(()) |
| })(); |
| }, |
| _ => unreachable!(), |
| } |
| err.emit(); |
| error_found = true; |
| } |
| } |
| if error_found { |
| Err(ErrorReported) |
| } else { |
| Ok(()) |
| } |
| } |
| |
| pub fn compare_const_impl<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_c: &ty::AssocItem, |
| impl_c_span: Span, |
| trait_c: &ty::AssocItem, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| ) { |
| debug!("compare_const_impl(impl_trait_ref={:?})", impl_trait_ref); |
| |
| tcx.infer_ctxt().enter(|infcx| { |
| let param_env = tcx.param_env(impl_c.def_id); |
| let inh = Inherited::new(infcx, impl_c.def_id); |
| let infcx = &inh.infcx; |
| |
| // The below is for the most part highly similar to the procedure |
| // for methods above. It is simpler in many respects, especially |
| // because we shouldn't really have to deal with lifetimes or |
| // predicates. In fact some of this should probably be put into |
| // shared functions because of DRY violations... |
| let trait_to_impl_substs = impl_trait_ref.substs; |
| |
| // Create a parameter environment that represents the implementation's |
| // method. |
| let impl_c_hir_id = tcx.hir().as_local_hir_id(impl_c.def_id).unwrap(); |
| |
| // Compute placeholder form of impl and trait const tys. |
| let impl_ty = tcx.type_of(impl_c.def_id); |
| let trait_ty = tcx.type_of(trait_c.def_id).subst(tcx, trait_to_impl_substs); |
| let mut cause = ObligationCause::misc(impl_c_span, impl_c_hir_id); |
| |
| // There is no "body" here, so just pass dummy id. |
| let impl_ty = inh.normalize_associated_types_in(impl_c_span, |
| impl_c_hir_id, |
| param_env, |
| &impl_ty); |
| |
| debug!("compare_const_impl: impl_ty={:?}", impl_ty); |
| |
| let trait_ty = inh.normalize_associated_types_in(impl_c_span, |
| impl_c_hir_id, |
| param_env, |
| &trait_ty); |
| |
| debug!("compare_const_impl: trait_ty={:?}", trait_ty); |
| |
| let err = infcx.at(&cause, param_env) |
| .sup(trait_ty, impl_ty) |
| .map(|ok| inh.register_infer_ok_obligations(ok)); |
| |
| if let Err(terr) = err { |
| debug!("checking associated const for compatibility: impl ty {:?}, trait ty {:?}", |
| impl_ty, |
| trait_ty); |
| |
| // Locate the Span containing just the type of the offending impl |
| match tcx.hir().expect_impl_item(impl_c_hir_id).kind { |
| ImplItemKind::Const(ref ty, _) => cause.span = ty.span, |
| _ => bug!("{:?} is not a impl const", impl_c), |
| } |
| |
| let mut diag = struct_span_err!(tcx.sess, |
| cause.span, |
| E0326, |
| "implemented const `{}` has an incompatible type for \ |
| trait", |
| trait_c.ident); |
| |
| let trait_c_hir_id = tcx.hir().as_local_hir_id(trait_c.def_id); |
| let trait_c_span = trait_c_hir_id.map(|trait_c_hir_id| { |
| // Add a label to the Span containing just the type of the const |
| match tcx.hir().expect_trait_item(trait_c_hir_id).kind { |
| TraitItemKind::Const(ref ty, _) => ty.span, |
| _ => bug!("{:?} is not a trait const", trait_c), |
| } |
| }); |
| |
| infcx.note_type_err(&mut diag, |
| &cause, |
| trait_c_span.map(|span| (span, "type in trait".to_owned())), |
| Some(infer::ValuePairs::Types(ExpectedFound { |
| expected: trait_ty, |
| found: impl_ty, |
| })), |
| &terr); |
| diag.emit(); |
| } |
| |
| // Check that all obligations are satisfied by the implementation's |
| // version. |
| if let Err(ref errors) = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx) { |
| infcx.report_fulfillment_errors(errors, None, false); |
| return; |
| } |
| |
| let fcx = FnCtxt::new(&inh, param_env, impl_c_hir_id); |
| fcx.regionck_item(impl_c_hir_id, impl_c_span, &[]); |
| }); |
| } |
