| use super::potentially_plural_count; |
| use crate::errors::LifetimesOrBoundsMismatchOnTrait; |
| use hir::def_id::{DefId, LocalDefId}; |
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
| use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorGuaranteed}; |
| use rustc_hir as hir; |
| use rustc_hir::def::{DefKind, Res}; |
| use rustc_hir::intravisit; |
| use rustc_hir::{GenericParamKind, ImplItemKind, TraitItemKind}; |
| use rustc_infer::infer::outlives::env::OutlivesEnvironment; |
| use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
| use rustc_infer::infer::{self, TyCtxtInferExt}; |
| use rustc_infer::traits::util; |
| use rustc_middle::ty::error::{ExpectedFound, TypeError}; |
| use rustc_middle::ty::util::ExplicitSelf; |
| use rustc_middle::ty::InternalSubsts; |
| use rustc_middle::ty::{ |
| self, AssocItem, DefIdTree, Ty, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitable, |
| }; |
| use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt}; |
| use rustc_span::Span; |
| use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt; |
| use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _; |
| use rustc_trait_selection::traits::{ |
| self, ObligationCause, ObligationCauseCode, ObligationCtxt, Reveal, |
| }; |
| use std::iter; |
| |
| /// 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(crate) fn compare_impl_method<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| 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.def_span(impl_m.def_id); |
| |
| if let Err(_) = compare_self_type(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) { |
| return; |
| } |
| |
| if let Err(_) = compare_number_of_generics(tcx, impl_m, impl_m_span, trait_m, trait_item_span) { |
| return; |
| } |
| |
| if let Err(_) = compare_generic_param_kinds(tcx, impl_m, trait_m) { |
| return; |
| } |
| |
| if let Err(_) = |
| compare_number_of_method_arguments(tcx, impl_m, impl_m_span, trait_m, trait_item_span) |
| { |
| return; |
| } |
| |
| if let Err(_) = compare_synthetic_generics(tcx, impl_m, trait_m) { |
| return; |
| } |
| |
| if let Err(_) = compare_predicate_entailment(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) |
| { |
| return; |
| } |
| } |
| |
| /// This function is best explained by example. Consider a trait: |
| /// |
| /// trait Trait<'t, T> { |
| /// // `trait_m` |
| /// fn method<'a, M>(t: &'t T, m: &'a M) -> Self; |
| /// } |
| /// |
| /// And an impl: |
| /// |
| /// impl<'i, 'j, U> Trait<'j, &'i U> for Foo { |
| /// // `impl_m` |
| /// fn method<'b, N>(t: &'j &'i U, m: &'b N) -> Foo; |
| /// } |
| /// |
| /// We wish to decide if those two method types are compatible. |
| /// For this we have to show that, assuming the bounds of the impl hold, the |
| /// bounds of `trait_m` imply the bounds of `impl_m`. |
| /// |
| /// 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_placeholder_substs = {'i => 'i0, U => U0, N => N0 } |
| /// |
| /// Now we can apply `placeholder_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_placeholder_substs`, and also adding a mapping for the method |
| /// type parameters. We extend the mapping to also include |
| /// the method parameters. |
| /// |
| /// trait_to_placeholder_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_placeholder_substs`. We then build |
| /// `trait_to_placeholder_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 and check that |
| /// they hold. |
| #[instrument(level = "debug", skip(tcx, impl_m_span, impl_trait_ref))] |
| fn compare_predicate_entailment<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &AssocItem, |
| impl_m_span: Span, |
| trait_m: &AssocItem, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| ) -> Result<(), ErrorGuaranteed> { |
| 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`). |
| // |
| // FIXME(@lcnr): remove that after removing `cause.body_id` from |
| // obligations. |
| let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); |
| // We sometimes modify the span further down. |
| let mut cause = ObligationCause::new( |
| impl_m_span, |
| impl_m_hir_id, |
| ObligationCauseCode::CompareImplItemObligation { |
| impl_item_def_id: impl_m.def_id.expect_local(), |
| trait_item_def_id: trait_m.def_id, |
| kind: impl_m.kind, |
| }, |
| ); |
| |
| // Create mapping from impl to placeholder. |
| let impl_to_placeholder_substs = InternalSubsts::identity_for_item(tcx, impl_m.def_id); |
| |
| // Create mapping from trait to placeholder. |
| let trait_to_placeholder_substs = |
| impl_to_placeholder_substs.rebase_onto(tcx, impl_m.container_id(tcx), trait_to_impl_substs); |
| debug!("compare_impl_method: trait_to_placeholder_substs={:?}", trait_to_placeholder_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_item(tcx, impl_m, trait_m, &trait_m_generics, &impl_m_generics)?; |
| |
| // 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_placeholder_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, |
| hir::Constness::NotConst, |
| ); |
| let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause); |
| |
| let infcx = &tcx.infer_ctxt().build(); |
| let ocx = ObligationCtxt::new(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_placeholder_substs); |
| for (predicate, span) in iter::zip(impl_m_own_bounds.predicates, impl_m_own_bounds.spans) { |
| let normalize_cause = traits::ObligationCause::misc(span, impl_m_hir_id); |
| let traits::Normalized { value: predicate, obligations } = |
| traits::normalize(&mut selcx, param_env, normalize_cause, predicate); |
| |
| ocx.register_obligations(obligations); |
| let cause = ObligationCause::new( |
| span, |
| impl_m_hir_id, |
| ObligationCauseCode::CompareImplItemObligation { |
| impl_item_def_id: impl_m.def_id.expect_local(), |
| trait_item_def_id: trait_m.def_id, |
| kind: impl_m.kind, |
| }, |
| ); |
| ocx.register_obligation(traits::Obligation::new(cause, 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 mut wf_tys = FxHashSet::default(); |
| |
| let impl_sig = infcx.replace_bound_vars_with_fresh_vars( |
| impl_m_span, |
| infer::HigherRankedType, |
| tcx.fn_sig(impl_m.def_id), |
| ); |
| |
| let norm_cause = ObligationCause::misc(impl_m_span, impl_m_hir_id); |
| let impl_sig = ocx.normalize(norm_cause.clone(), param_env, impl_sig); |
| let impl_fty = tcx.mk_fn_ptr(ty::Binder::dummy(impl_sig)); |
| debug!("compare_impl_method: impl_fty={:?}", impl_fty); |
| |
| let trait_sig = tcx.bound_fn_sig(trait_m.def_id).subst(tcx, trait_to_placeholder_substs); |
| let trait_sig = tcx.liberate_late_bound_regions(impl_m.def_id, trait_sig); |
| |
| // Next, add all inputs and output as well-formed tys. Importantly, |
| // we have to do this before normalization, since the normalized ty may |
| // not contain the input parameters. See issue #87748. |
| wf_tys.extend(trait_sig.inputs_and_output.iter()); |
| let trait_sig = ocx.normalize(norm_cause, param_env, trait_sig); |
| // We also have to add the normalized trait signature |
| // as we don't normalize during implied bounds computation. |
| wf_tys.extend(trait_sig.inputs_and_output.iter()); |
| let trait_fty = tcx.mk_fn_ptr(ty::Binder::dummy(trait_sig)); |
| |
| debug!("compare_impl_method: trait_fty={:?}", trait_fty); |
| |
| // FIXME: We'd want to keep more accurate spans than "the method signature" when |
| // processing the comparison between the trait and impl fn, but we sadly lose them |
| // and point at the whole signature when a trait bound or specific input or output |
| // type would be more appropriate. In other places we have a `Vec<Span>` |
| // corresponding to their `Vec<Predicate>`, but we don't have that here. |
| // Fixing this would improve the output of test `issue-83765.rs`. |
| let mut result = infcx |
| .at(&cause, param_env) |
| .sup(trait_fty, impl_fty) |
| .map(|infer_ok| ocx.register_infer_ok_obligations(infer_ok)); |
| |
| // HACK(RPITIT): #101614. When we are trying to infer the hidden types for |
| // RPITITs, we need to equate the output tys instead of just subtyping. If |
| // we just use `sup` above, we'll end up `&'static str <: _#1t`, which causes |
| // us to infer `_#1t = #'_#2r str`, where `'_#2r` is unconstrained, which gets |
| // fixed up to `ReEmpty`, and which is certainly not what we want. |
| if trait_fty.has_infer_types() { |
| result = result.and_then(|()| { |
| infcx |
| .at(&cause, param_env) |
| .eq(trait_sig.output(), impl_sig.output()) |
| .map(|infer_ok| ocx.register_infer_ok_obligations(infer_ok)) |
| }); |
| } |
| |
| if let Err(terr) = 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, terr, &cause, impl_m, trait_m); |
| |
| cause.span = impl_err_span; |
| |
| let mut diag = struct_span_err!( |
| tcx.sess, |
| cause.span(), |
| E0053, |
| "method `{}` has an incompatible type for trait", |
| trait_m.name |
| ); |
| match &terr { |
| TypeError::ArgumentMutability(0) | TypeError::ArgumentSorts(_, 0) |
| if trait_m.fn_has_self_parameter => |
| { |
| let ty = trait_sig.inputs()[0]; |
| let sugg = match ExplicitSelf::determine(ty, |_| ty == impl_trait_ref.self_ty()) { |
| ExplicitSelf::ByValue => "self".to_owned(), |
| ExplicitSelf::ByReference(_, hir::Mutability::Not) => "&self".to_owned(), |
| ExplicitSelf::ByReference(_, hir::Mutability::Mut) => "&mut self".to_owned(), |
| _ => format!("self: {ty}"), |
| }; |
| |
| // When the `impl` receiver is an arbitrary self type, like `self: Box<Self>`, the |
| // span points only at the type `Box<Self`>, but we want to cover the whole |
| // argument pattern and type. |
| let span = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
| ImplItemKind::Fn(ref sig, body) => tcx |
| .hir() |
| .body_param_names(body) |
| .zip(sig.decl.inputs.iter()) |
| .map(|(param, ty)| param.span.to(ty.span)) |
| .next() |
| .unwrap_or(impl_err_span), |
| _ => bug!("{:?} is not a method", impl_m), |
| }; |
| |
| diag.span_suggestion( |
| span, |
| "change the self-receiver type to match the trait", |
| sugg, |
| Applicability::MachineApplicable, |
| ); |
| } |
| TypeError::ArgumentMutability(i) | TypeError::ArgumentSorts(_, i) => { |
| if trait_sig.inputs().len() == *i { |
| // Suggestion to change output type. We do not suggest in `async` functions |
| // to avoid complex logic or incorrect output. |
| match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
| ImplItemKind::Fn(ref sig, _) |
| if sig.header.asyncness == hir::IsAsync::NotAsync => |
| { |
| let msg = "change the output type to match the trait"; |
| let ap = Applicability::MachineApplicable; |
| match sig.decl.output { |
| hir::FnRetTy::DefaultReturn(sp) => { |
| let sugg = format!("-> {} ", trait_sig.output()); |
| diag.span_suggestion_verbose(sp, msg, sugg, ap); |
| } |
| hir::FnRetTy::Return(hir_ty) => { |
| let sugg = trait_sig.output(); |
| diag.span_suggestion(hir_ty.span, msg, sugg, ap); |
| } |
| }; |
| } |
| _ => {} |
| }; |
| } else if let Some(trait_ty) = trait_sig.inputs().get(*i) { |
| diag.span_suggestion( |
| impl_err_span, |
| "change the parameter type to match the trait", |
| trait_ty, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| _ => {} |
| } |
| |
| infcx.err_ctxt().note_type_err( |
| &mut diag, |
| &cause, |
| trait_err_span.map(|sp| (sp, "type in trait".to_owned())), |
| Some(infer::ValuePairs::Terms(ExpectedFound { |
| expected: trait_fty.into(), |
| found: impl_fty.into(), |
| })), |
| terr, |
| false, |
| false, |
| ); |
| |
| return Err(diag.emit()); |
| } |
| |
| // Check that all obligations are satisfied by the implementation's |
| // version. |
| let errors = ocx.select_all_or_error(); |
| if !errors.is_empty() { |
| let reported = infcx.err_ctxt().report_fulfillment_errors(&errors, None, false); |
| return Err(reported); |
| } |
| |
| // Finally, resolve all regions. This catches wily misuses of |
| // lifetime parameters. |
| let outlives_environment = OutlivesEnvironment::with_bounds( |
| param_env, |
| Some(infcx), |
| infcx.implied_bounds_tys(param_env, impl_m_hir_id, wf_tys), |
| ); |
| infcx.check_region_obligations_and_report_errors( |
| impl_m.def_id.expect_local(), |
| &outlives_environment, |
| ); |
| |
| Ok(()) |
| } |
| |
| pub fn collect_trait_impl_trait_tys<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| def_id: DefId, |
| ) -> Result<&'tcx FxHashMap<DefId, Ty<'tcx>>, ErrorGuaranteed> { |
| let impl_m = tcx.opt_associated_item(def_id).unwrap(); |
| let trait_m = tcx.opt_associated_item(impl_m.trait_item_def_id.unwrap()).unwrap(); |
| let impl_trait_ref = tcx.impl_trait_ref(impl_m.impl_container(tcx).unwrap()).unwrap(); |
| let param_env = tcx.param_env(def_id); |
| |
| let trait_to_impl_substs = impl_trait_ref.substs; |
| |
| let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); |
| let return_span = tcx.hir().fn_decl_by_hir_id(impl_m_hir_id).unwrap().output.span(); |
| let cause = ObligationCause::new( |
| return_span, |
| impl_m_hir_id, |
| ObligationCauseCode::CompareImplItemObligation { |
| impl_item_def_id: impl_m.def_id.expect_local(), |
| trait_item_def_id: trait_m.def_id, |
| kind: impl_m.kind, |
| }, |
| ); |
| |
| // Create mapping from impl to placeholder. |
| let impl_to_placeholder_substs = InternalSubsts::identity_for_item(tcx, impl_m.def_id); |
| |
| // Create mapping from trait to placeholder. |
| let trait_to_placeholder_substs = |
| impl_to_placeholder_substs.rebase_onto(tcx, impl_m.container_id(tcx), trait_to_impl_substs); |
| |
| let infcx = &tcx.infer_ctxt().build(); |
| let ocx = ObligationCtxt::new(infcx); |
| |
| let norm_cause = ObligationCause::misc(return_span, impl_m_hir_id); |
| let impl_sig = ocx.normalize( |
| norm_cause.clone(), |
| param_env, |
| infcx.replace_bound_vars_with_fresh_vars( |
| return_span, |
| infer::HigherRankedType, |
| tcx.fn_sig(impl_m.def_id), |
| ), |
| ); |
| let impl_return_ty = impl_sig.output(); |
| |
| let mut collector = ImplTraitInTraitCollector::new(&ocx, return_span, param_env, impl_m_hir_id); |
| let unnormalized_trait_sig = tcx |
| .liberate_late_bound_regions( |
| impl_m.def_id, |
| tcx.bound_fn_sig(trait_m.def_id).subst(tcx, trait_to_placeholder_substs), |
| ) |
| .fold_with(&mut collector); |
| let trait_sig = ocx.normalize(norm_cause.clone(), param_env, unnormalized_trait_sig); |
| let trait_return_ty = trait_sig.output(); |
| |
| let wf_tys = FxHashSet::from_iter( |
| unnormalized_trait_sig.inputs_and_output.iter().chain(trait_sig.inputs_and_output.iter()), |
| ); |
| |
| match infcx.at(&cause, param_env).eq(trait_return_ty, impl_return_ty) { |
| Ok(infer::InferOk { value: (), obligations }) => { |
| ocx.register_obligations(obligations); |
| } |
| Err(terr) => { |
| let mut diag = struct_span_err!( |
| tcx.sess, |
| cause.span(), |
| E0053, |
| "method `{}` has an incompatible return type for trait", |
| trait_m.name |
| ); |
| let hir = tcx.hir(); |
| infcx.err_ctxt().note_type_err( |
| &mut diag, |
| &cause, |
| hir.get_if_local(impl_m.def_id) |
| .and_then(|node| node.fn_decl()) |
| .map(|decl| (decl.output.span(), "return type in trait".to_owned())), |
| Some(infer::ValuePairs::Terms(ExpectedFound { |
| expected: trait_return_ty.into(), |
| found: impl_return_ty.into(), |
| })), |
| terr, |
| false, |
| false, |
| ); |
| return Err(diag.emit()); |
| } |
| } |
| |
| // Unify the whole function signature. We need to do this to fully infer |
| // the lifetimes of the return type, but do this after unifying just the |
| // return types, since we want to avoid duplicating errors from |
| // `compare_predicate_entailment`. |
| match infcx |
| .at(&cause, param_env) |
| .eq(tcx.mk_fn_ptr(ty::Binder::dummy(trait_sig)), tcx.mk_fn_ptr(ty::Binder::dummy(impl_sig))) |
| { |
| Ok(infer::InferOk { value: (), obligations }) => { |
| ocx.register_obligations(obligations); |
| } |
| Err(terr) => { |
| let guar = tcx.sess.delay_span_bug( |
| return_span, |
| format!("could not unify `{trait_sig}` and `{impl_sig}`: {terr:?}"), |
| ); |
| return Err(guar); |
| } |
| } |
| |
| // Check that all obligations are satisfied by the implementation's |
| // RPITs. |
| let errors = ocx.select_all_or_error(); |
| if !errors.is_empty() { |
| let reported = infcx.err_ctxt().report_fulfillment_errors(&errors, None, false); |
| return Err(reported); |
| } |
| |
| // Finally, resolve all regions. This catches wily misuses of |
| // lifetime parameters. |
| let outlives_environment = OutlivesEnvironment::with_bounds( |
| param_env, |
| Some(infcx), |
| infcx.implied_bounds_tys(param_env, impl_m_hir_id, wf_tys), |
| ); |
| infcx.check_region_obligations_and_report_errors( |
| impl_m.def_id.expect_local(), |
| &outlives_environment, |
| ); |
| |
| let mut collected_tys = FxHashMap::default(); |
| for (def_id, (ty, substs)) in collector.types { |
| match infcx.fully_resolve(ty) { |
| Ok(ty) => { |
| // `ty` contains free regions that we created earlier while liberating the |
| // trait fn signature. However, projection normalization expects `ty` to |
| // contains `def_id`'s early-bound regions. |
| let id_substs = InternalSubsts::identity_for_item(tcx, def_id); |
| debug!(?id_substs, ?substs); |
| let map: FxHashMap<ty::GenericArg<'tcx>, ty::GenericArg<'tcx>> = |
| std::iter::zip(substs, id_substs).collect(); |
| debug!(?map); |
| |
| // NOTE(compiler-errors): RPITITs, like all other RPITs, have early-bound |
| // region substs that are synthesized during AST lowering. These are substs |
| // that are appended to the parent substs (trait and trait method). However, |
| // we're trying to infer the unsubstituted type value of the RPITIT inside |
| // the *impl*, so we can later use the impl's method substs to normalize |
| // an RPITIT to a concrete type (`confirm_impl_trait_in_trait_candidate`). |
| // |
| // Due to the design of RPITITs, during AST lowering, we have no idea that |
| // an impl method corresponds to a trait method with RPITITs in it. Therefore, |
| // we don't have a list of early-bound region substs for the RPITIT in the impl. |
| // Since early region parameters are index-based, we can't just rebase these |
| // (trait method) early-bound region substs onto the impl, and there's no |
| // guarantee that the indices from the trait substs and impl substs line up. |
| // So to fix this, we subtract the number of trait substs and add the number of |
| // impl substs to *renumber* these early-bound regions to their corresponding |
| // indices in the impl's substitutions list. |
| // |
| // Also, we only need to account for a difference in trait and impl substs, |
| // since we previously enforce that the trait method and impl method have the |
| // same generics. |
| let num_trait_substs = trait_to_impl_substs.len(); |
| let num_impl_substs = tcx.generics_of(impl_m.container_id(tcx)).params.len(); |
| let ty = tcx.fold_regions(ty, |region, _| { |
| let (ty::ReFree(_) | ty::ReEarlyBound(_)) = region.kind() else { return region; }; |
| let Some(ty::ReEarlyBound(e)) = map.get(®ion.into()).map(|r| r.expect_region().kind()) |
| else { |
| tcx |
| .sess |
| .delay_span_bug( |
| return_span, |
| "expected ReFree to map to ReEarlyBound" |
| ); |
| return tcx.lifetimes.re_static; |
| }; |
| tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion { |
| def_id: e.def_id, |
| name: e.name, |
| index: (e.index as usize - num_trait_substs + num_impl_substs) as u32, |
| })) |
| }); |
| debug!(%ty); |
| collected_tys.insert(def_id, ty); |
| } |
| Err(err) => { |
| tcx.sess.delay_span_bug( |
| return_span, |
| format!("could not fully resolve: {ty} => {err:?}"), |
| ); |
| collected_tys.insert(def_id, tcx.ty_error()); |
| } |
| } |
| } |
| |
| Ok(&*tcx.arena.alloc(collected_tys)) |
| } |
| |
| struct ImplTraitInTraitCollector<'a, 'tcx> { |
| ocx: &'a ObligationCtxt<'a, 'tcx>, |
| types: FxHashMap<DefId, (Ty<'tcx>, ty::SubstsRef<'tcx>)>, |
| span: Span, |
| param_env: ty::ParamEnv<'tcx>, |
| body_id: hir::HirId, |
| } |
| |
| impl<'a, 'tcx> ImplTraitInTraitCollector<'a, 'tcx> { |
| fn new( |
| ocx: &'a ObligationCtxt<'a, 'tcx>, |
| span: Span, |
| param_env: ty::ParamEnv<'tcx>, |
| body_id: hir::HirId, |
| ) -> Self { |
| ImplTraitInTraitCollector { ocx, types: FxHashMap::default(), span, param_env, body_id } |
| } |
| } |
| |
| impl<'tcx> TypeFolder<'tcx> for ImplTraitInTraitCollector<'_, 'tcx> { |
| fn tcx<'a>(&'a self) -> TyCtxt<'tcx> { |
| self.ocx.infcx.tcx |
| } |
| |
| fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { |
| if let ty::Projection(proj) = ty.kind() |
| && self.tcx().def_kind(proj.item_def_id) == DefKind::ImplTraitPlaceholder |
| { |
| if let Some((ty, _)) = self.types.get(&proj.item_def_id) { |
| return *ty; |
| } |
| //FIXME(RPITIT): Deny nested RPITIT in substs too |
| if proj.substs.has_escaping_bound_vars() { |
| bug!("FIXME(RPITIT): error here"); |
| } |
| // Replace with infer var |
| let infer_ty = self.ocx.infcx.next_ty_var(TypeVariableOrigin { |
| span: self.span, |
| kind: TypeVariableOriginKind::MiscVariable, |
| }); |
| self.types.insert(proj.item_def_id, (infer_ty, proj.substs)); |
| // Recurse into bounds |
| for (pred, pred_span) in self.tcx().bound_explicit_item_bounds(proj.item_def_id).subst_iter_copied(self.tcx(), proj.substs) { |
| let pred = pred.fold_with(self); |
| let pred = self.ocx.normalize( |
| ObligationCause::misc(self.span, self.body_id), |
| self.param_env, |
| pred, |
| ); |
| |
| self.ocx.register_obligation(traits::Obligation::new( |
| ObligationCause::new( |
| self.span, |
| self.body_id, |
| ObligationCauseCode::BindingObligation(proj.item_def_id, pred_span), |
| ), |
| self.param_env, |
| pred, |
| )); |
| } |
| infer_ty |
| } else { |
| ty.super_fold_with(self) |
| } |
| } |
| } |
| |
| fn check_region_bounds_on_impl_item<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| trait_m: &ty::AssocItem, |
| trait_generics: &ty::Generics, |
| impl_generics: &ty::Generics, |
| ) -> Result<(), ErrorGuaranteed> { |
| let trait_params = trait_generics.own_counts().lifetimes; |
| let impl_params = impl_generics.own_counts().lifetimes; |
| |
| debug!( |
| "check_region_bounds_on_impl_item: \ |
| trait_generics={:?} \ |
| impl_generics={:?}", |
| trait_generics, impl_generics |
| ); |
| |
| // 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 span = tcx |
| .hir() |
| .get_generics(impl_m.def_id.expect_local()) |
| .expect("expected impl item to have generics or else we can't compare them") |
| .span; |
| let generics_span = if let Some(local_def_id) = trait_m.def_id.as_local() { |
| Some( |
| tcx.hir() |
| .get_generics(local_def_id) |
| .expect("expected trait item to have generics or else we can't compare them") |
| .span, |
| ) |
| } else { |
| None |
| }; |
| |
| let reported = tcx.sess.emit_err(LifetimesOrBoundsMismatchOnTrait { |
| span, |
| item_kind: assoc_item_kind_str(impl_m), |
| ident: impl_m.ident(tcx), |
| generics_span, |
| }); |
| return Err(reported); |
| } |
| |
| Ok(()) |
| } |
| |
| #[instrument(level = "debug", skip(infcx))] |
| fn extract_spans_for_error_reporting<'tcx>( |
| infcx: &infer::InferCtxt<'tcx>, |
| terr: TypeError<'_>, |
| cause: &ObligationCause<'tcx>, |
| impl_m: &ty::AssocItem, |
| trait_m: &ty::AssocItem, |
| ) -> (Span, Option<Span>) { |
| let tcx = infcx.tcx; |
| let mut impl_args = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
| ImplItemKind::Fn(ref sig, _) => { |
| sig.decl.inputs.iter().map(|t| t.span).chain(iter::once(sig.decl.output.span())) |
| } |
| _ => bug!("{:?} is not a method", impl_m), |
| }; |
| let trait_args = |
| trait_m.def_id.as_local().map(|def_id| match tcx.hir().expect_trait_item(def_id).kind { |
| TraitItemKind::Fn(ref sig, _) => { |
| sig.decl.inputs.iter().map(|t| t.span).chain(iter::once(sig.decl.output.span())) |
| } |
| _ => bug!("{:?} is not a TraitItemKind::Fn", trait_m), |
| }); |
| |
| match terr { |
| TypeError::ArgumentMutability(i) => { |
| (impl_args.nth(i).unwrap(), trait_args.and_then(|mut args| args.nth(i))) |
| } |
| TypeError::ArgumentSorts(ExpectedFound { .. }, i) => { |
| (impl_args.nth(i).unwrap(), trait_args.and_then(|mut args| args.nth(i))) |
| } |
| _ => (cause.span(), 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<(), ErrorGuaranteed> { |
| // 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); |
| let param_env = ty::ParamEnv::reveal_all(); |
| |
| let infcx = tcx.infer_ctxt().build(); |
| let self_arg_ty = tcx.liberate_late_bound_regions(method.def_id, 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::Not) => "&self".to_owned(), |
| ExplicitSelf::ByReference(_, hir::Mutability::Mut) => "&mut self".to_owned(), |
| _ => format!("self: {self_arg_ty}"), |
| } |
| }; |
| |
| match (trait_m.fn_has_self_parameter, impl_m.fn_has_self_parameter) { |
| (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.name, |
| self_descr |
| ); |
| err.span_label(impl_m_span, format!("`{self_descr}` used in impl")); |
| 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.name, trait_m.signature(tcx)); |
| } |
| let reported = err.emit(); |
| return Err(reported); |
| } |
| |
| (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.name, |
| self_descr |
| ); |
| err.span_label(impl_m_span, format!("expected `{self_descr}` in impl")); |
| if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
| err.span_label(span, format!("`{self_descr}` used in trait")); |
| } else { |
| err.note_trait_signature(trait_m.name, trait_m.signature(tcx)); |
| } |
| let reported = err.emit(); |
| return Err(reported); |
| } |
| } |
| |
| Ok(()) |
| } |
| |
| /// Checks that the number of generics on a given assoc item in a trait impl is the same |
| /// as the number of generics on the respective assoc item in the trait definition. |
| /// |
| /// For example this code emits the errors in the following code: |
| /// ``` |
| /// trait Trait { |
| /// fn foo(); |
| /// type Assoc<T>; |
| /// } |
| /// |
| /// impl Trait for () { |
| /// fn foo<T>() {} |
| /// //~^ error |
| /// type Assoc = u32; |
| /// //~^ error |
| /// } |
| /// ``` |
| /// |
| /// Notably this does not error on `foo<T>` implemented as `foo<const N: u8>` or |
| /// `foo<const N: u8>` implemented as `foo<const N: u32>`. This is handled in |
| /// [`compare_generic_param_kinds`]. This function also does not handle lifetime parameters |
| fn compare_number_of_generics<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_: &ty::AssocItem, |
| _impl_span: Span, |
| trait_: &ty::AssocItem, |
| trait_span: Option<Span>, |
| ) -> Result<(), ErrorGuaranteed> { |
| let trait_own_counts = tcx.generics_of(trait_.def_id).own_counts(); |
| let impl_own_counts = tcx.generics_of(impl_.def_id).own_counts(); |
| |
| // This avoids us erroring on `foo<T>` implemented as `foo<const N: u8>` as this is implemented |
| // in `compare_generic_param_kinds` which will give a nicer error message than something like: |
| // "expected 1 type parameter, found 0 type parameters" |
| if (trait_own_counts.types + trait_own_counts.consts) |
| == (impl_own_counts.types + impl_own_counts.consts) |
| { |
| return Ok(()); |
| } |
| |
| let matchings = [ |
| ("type", trait_own_counts.types, impl_own_counts.types), |
| ("const", trait_own_counts.consts, impl_own_counts.consts), |
| ]; |
| |
| let item_kind = assoc_item_kind_str(impl_); |
| |
| let mut err_occurred = None; |
| for (kind, trait_count, impl_count) in matchings { |
| if impl_count != trait_count { |
| let arg_spans = |kind: ty::AssocKind, generics: &hir::Generics<'_>| { |
| let mut spans = generics |
| .params |
| .iter() |
| .filter(|p| match p.kind { |
| hir::GenericParamKind::Lifetime { |
| kind: hir::LifetimeParamKind::Elided, |
| } => { |
| // A fn can have an arbitrary number of extra elided lifetimes for the |
| // same signature. |
| !matches!(kind, ty::AssocKind::Fn) |
| } |
| _ => true, |
| }) |
| .map(|p| p.span) |
| .collect::<Vec<Span>>(); |
| if spans.is_empty() { |
| spans = vec![generics.span] |
| } |
| spans |
| }; |
| let (trait_spans, impl_trait_spans) = if let Some(def_id) = trait_.def_id.as_local() { |
| let trait_item = tcx.hir().expect_trait_item(def_id); |
| let arg_spans: Vec<Span> = arg_spans(trait_.kind, trait_item.generics); |
| let impl_trait_spans: Vec<Span> = trait_item |
| .generics |
| .params |
| .iter() |
| .filter_map(|p| match p.kind { |
| GenericParamKind::Type { synthetic: true, .. } => Some(p.span), |
| _ => None, |
| }) |
| .collect(); |
| (Some(arg_spans), impl_trait_spans) |
| } else { |
| (trait_span.map(|s| vec![s]), vec![]) |
| }; |
| |
| let impl_item = tcx.hir().expect_impl_item(impl_.def_id.expect_local()); |
| let impl_item_impl_trait_spans: Vec<Span> = impl_item |
| .generics |
| .params |
| .iter() |
| .filter_map(|p| match p.kind { |
| GenericParamKind::Type { synthetic: true, .. } => Some(p.span), |
| _ => None, |
| }) |
| .collect(); |
| let spans = arg_spans(impl_.kind, impl_item.generics); |
| let span = spans.first().copied(); |
| |
| let mut err = tcx.sess.struct_span_err_with_code( |
| spans, |
| &format!( |
| "{} `{}` has {} {kind} parameter{} but its trait \ |
| declaration has {} {kind} parameter{}", |
| item_kind, |
| trait_.name, |
| 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"); |
| } |
| |
| let reported = err.emit(); |
| err_occurred = Some(reported); |
| } |
| } |
| |
| if let Some(reported) = err_occurred { Err(reported) } 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<(), ErrorGuaranteed> { |
| 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_span = if let Some(def_id) = trait_m.def_id.as_local() { |
| match tcx.hir().expect_trait_item(def_id).kind { |
| TraitItemKind::Fn(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 { |
| arg.span.with_lo(trait_m_sig.decl.inputs[0].span.lo()) |
| }) |
| } else { |
| trait_item_span |
| } |
| } |
| _ => bug!("{:?} is not a method", impl_m), |
| } |
| } else { |
| trait_item_span |
| }; |
| let impl_span = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
| ImplItemKind::Fn(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 { |
| arg.span.with_lo(impl_m_sig.decl.inputs[0].span.lo()) |
| } |
| } 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.name, |
| 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.name, trait_m.signature(tcx)); |
| } |
| err.span_label( |
| impl_span, |
| format!( |
| "expected {}, found {}", |
| potentially_plural_count(trait_number_args, "parameter"), |
| impl_number_args |
| ), |
| ); |
| let reported = err.emit(); |
| return Err(reported); |
| } |
| |
| Ok(()) |
| } |
| |
| fn compare_synthetic_generics<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_m: &ty::AssocItem, |
| trait_m: &ty::AssocItem, |
| ) -> Result<(), ErrorGuaranteed> { |
| // 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 = None; |
| 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 |
| iter::zip(impl_m_type_params, trait_m_type_params) |
| { |
| if impl_synthetic != trait_synthetic { |
| let impl_def_id = impl_def_id.expect_local(); |
| let impl_span = tcx.def_span(impl_def_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.name |
| ); |
| 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 |
| (true, false) => { |
| 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.opt_item_name(trait_def_id)?; |
| let trait_m = trait_m.def_id.as_local()?; |
| let trait_m = tcx.hir().expect_trait_item(trait_m); |
| |
| let impl_m = impl_m.def_id.as_local()?; |
| let impl_m = tcx.hir().expect_impl_item(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.def_ident_span(impl_def_id)?.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.to_string()), |
| // 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. |
| (false, true) => { |
| err.span_label(impl_span, "expected `impl Trait`, found generic parameter"); |
| (|| { |
| let impl_m = impl_m.def_id.as_local()?; |
| let impl_m = tcx.hir().expect_impl_item(impl_m); |
| let input_tys = match impl_m.kind { |
| hir::ImplItemKind::Fn(ref sig, _) => sig.decl.inputs, |
| _ => unreachable!(), |
| }; |
| struct Visitor(Option<Span>, hir::def_id::LocalDefId); |
| impl<'v> intravisit::Visitor<'v> for Visitor { |
| fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) { |
| intravisit::walk_ty(self, ty); |
| if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = |
| ty.kind |
| && let Res::Def(DefKind::TyParam, def_id) = path.res |
| && def_id == self.1.to_def_id() |
| { |
| self.0 = Some(ty.span); |
| } |
| } |
| } |
| let mut visitor = Visitor(None, impl_def_id); |
| for ty in input_tys { |
| intravisit::Visitor::visit_ty(&mut visitor, ty); |
| } |
| let span = visitor.0?; |
| |
| let bounds = impl_m.generics.bounds_for_param(impl_def_id).next()?.bounds; |
| 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!(), |
| } |
| let reported = err.emit(); |
| error_found = Some(reported); |
| } |
| } |
| if let Some(reported) = error_found { Err(reported) } else { Ok(()) } |
| } |
| |
| /// Checks that all parameters in the generics of a given assoc item in a trait impl have |
| /// the same kind as the respective generic parameter in the trait def. |
| /// |
| /// For example all 4 errors in the following code are emitted here: |
| /// ``` |
| /// trait Foo { |
| /// fn foo<const N: u8>(); |
| /// type bar<const N: u8>; |
| /// fn baz<const N: u32>(); |
| /// type blah<T>; |
| /// } |
| /// |
| /// impl Foo for () { |
| /// fn foo<const N: u64>() {} |
| /// //~^ error |
| /// type bar<const N: u64> {} |
| /// //~^ error |
| /// fn baz<T>() {} |
| /// //~^ error |
| /// type blah<const N: i64> = u32; |
| /// //~^ error |
| /// } |
| /// ``` |
| /// |
| /// This function does not handle lifetime parameters |
| fn compare_generic_param_kinds<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_item: &ty::AssocItem, |
| trait_item: &ty::AssocItem, |
| ) -> Result<(), ErrorGuaranteed> { |
| assert_eq!(impl_item.kind, trait_item.kind); |
| |
| let ty_const_params_of = |def_id| { |
| tcx.generics_of(def_id).params.iter().filter(|param| { |
| matches!( |
| param.kind, |
| GenericParamDefKind::Const { .. } | GenericParamDefKind::Type { .. } |
| ) |
| }) |
| }; |
| |
| for (param_impl, param_trait) in |
| iter::zip(ty_const_params_of(impl_item.def_id), ty_const_params_of(trait_item.def_id)) |
| { |
| use GenericParamDefKind::*; |
| if match (¶m_impl.kind, ¶m_trait.kind) { |
| (Const { .. }, Const { .. }) |
| if tcx.type_of(param_impl.def_id) != tcx.type_of(param_trait.def_id) => |
| { |
| true |
| } |
| (Const { .. }, Type { .. }) | (Type { .. }, Const { .. }) => true, |
| // this is exhaustive so that anyone adding new generic param kinds knows |
| // to make sure this error is reported for them. |
| (Const { .. }, Const { .. }) | (Type { .. }, Type { .. }) => false, |
| (Lifetime { .. }, _) | (_, Lifetime { .. }) => unreachable!(), |
| } { |
| let param_impl_span = tcx.def_span(param_impl.def_id); |
| let param_trait_span = tcx.def_span(param_trait.def_id); |
| |
| let mut err = struct_span_err!( |
| tcx.sess, |
| param_impl_span, |
| E0053, |
| "{} `{}` has an incompatible generic parameter for trait `{}`", |
| assoc_item_kind_str(&impl_item), |
| trait_item.name, |
| &tcx.def_path_str(tcx.parent(trait_item.def_id)) |
| ); |
| |
| let make_param_message = |prefix: &str, param: &ty::GenericParamDef| match param.kind { |
| Const { .. } => { |
| format!("{} const parameter of type `{}`", prefix, tcx.type_of(param.def_id)) |
| } |
| Type { .. } => format!("{} type parameter", prefix), |
| Lifetime { .. } => unreachable!(), |
| }; |
| |
| let trait_header_span = tcx.def_ident_span(tcx.parent(trait_item.def_id)).unwrap(); |
| err.span_label(trait_header_span, ""); |
| err.span_label(param_trait_span, make_param_message("expected", param_trait)); |
| |
| let impl_header_span = tcx.def_span(tcx.parent(impl_item.def_id)); |
| err.span_label(impl_header_span, ""); |
| err.span_label(param_impl_span, make_param_message("found", param_impl)); |
| |
| let reported = err.emit(); |
| return Err(reported); |
| } |
| } |
| |
| Ok(()) |
| } |
| |
| /// Use `tcx.compare_assoc_const_impl_item_with_trait_item` instead |
| pub(crate) fn raw_compare_const_impl<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| (impl_const_item_def, trait_const_item_def): (LocalDefId, DefId), |
| ) -> Result<(), ErrorGuaranteed> { |
| let impl_const_item = tcx.associated_item(impl_const_item_def); |
| let trait_const_item = tcx.associated_item(trait_const_item_def); |
| let impl_trait_ref = tcx.impl_trait_ref(impl_const_item.container_id(tcx)).unwrap(); |
| debug!("compare_const_impl(impl_trait_ref={:?})", impl_trait_ref); |
| |
| let impl_c_span = tcx.def_span(impl_const_item_def.to_def_id()); |
| |
| let infcx = tcx.infer_ctxt().build(); |
| let param_env = tcx.param_env(impl_const_item_def.to_def_id()); |
| let ocx = ObligationCtxt::new(&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().local_def_id_to_hir_id(impl_const_item_def); |
| |
| // Compute placeholder form of impl and trait const tys. |
| let impl_ty = tcx.type_of(impl_const_item_def.to_def_id()); |
| let trait_ty = tcx.bound_type_of(trait_const_item_def).subst(tcx, trait_to_impl_substs); |
| let mut cause = ObligationCause::new( |
| impl_c_span, |
| impl_c_hir_id, |
| ObligationCauseCode::CompareImplItemObligation { |
| impl_item_def_id: impl_const_item_def, |
| trait_item_def_id: trait_const_item_def, |
| kind: impl_const_item.kind, |
| }, |
| ); |
| |
| // There is no "body" here, so just pass dummy id. |
| let impl_ty = ocx.normalize(cause.clone(), param_env, impl_ty); |
| |
| debug!("compare_const_impl: impl_ty={:?}", impl_ty); |
| |
| let trait_ty = ocx.normalize(cause.clone(), 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| ocx.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_const_item_def).kind { |
| ImplItemKind::Const(ref ty, _) => cause.span = ty.span, |
| _ => bug!("{:?} is not a impl const", impl_const_item), |
| } |
| |
| let mut diag = struct_span_err!( |
| tcx.sess, |
| cause.span, |
| E0326, |
| "implemented const `{}` has an incompatible type for trait", |
| trait_const_item.name |
| ); |
| |
| let trait_c_span = trait_const_item_def.as_local().map(|trait_c_def_id| { |
| // Add a label to the Span containing just the type of the const |
| match tcx.hir().expect_trait_item(trait_c_def_id).kind { |
| TraitItemKind::Const(ref ty, _) => ty.span, |
| _ => bug!("{:?} is not a trait const", trait_const_item), |
| } |
| }); |
| |
| infcx.err_ctxt().note_type_err( |
| &mut diag, |
| &cause, |
| trait_c_span.map(|span| (span, "type in trait".to_owned())), |
| Some(infer::ValuePairs::Terms(ExpectedFound { |
| expected: trait_ty.into(), |
| found: impl_ty.into(), |
| })), |
| terr, |
| false, |
| false, |
| ); |
| return Err(diag.emit()); |
| }; |
| |
| // Check that all obligations are satisfied by the implementation's |
| // version. |
| let errors = ocx.select_all_or_error(); |
| if !errors.is_empty() { |
| return Err(infcx.err_ctxt().report_fulfillment_errors(&errors, None, false)); |
| } |
| |
| // FIXME return `ErrorReported` if region obligations error? |
| let outlives_environment = OutlivesEnvironment::new(param_env); |
| infcx.check_region_obligations_and_report_errors(impl_const_item_def, &outlives_environment); |
| Ok(()) |
| } |
| |
| pub(crate) fn compare_ty_impl<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_ty: &ty::AssocItem, |
| impl_ty_span: Span, |
| trait_ty: &ty::AssocItem, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| trait_item_span: Option<Span>, |
| ) { |
| debug!("compare_impl_type(impl_trait_ref={:?})", impl_trait_ref); |
| |
| let _: Result<(), ErrorGuaranteed> = (|| { |
| compare_number_of_generics(tcx, impl_ty, impl_ty_span, trait_ty, trait_item_span)?; |
| |
| compare_generic_param_kinds(tcx, impl_ty, trait_ty)?; |
| |
| let sp = tcx.def_span(impl_ty.def_id); |
| compare_type_predicate_entailment(tcx, impl_ty, sp, trait_ty, impl_trait_ref)?; |
| |
| check_type_bounds(tcx, trait_ty, impl_ty, impl_ty_span, impl_trait_ref) |
| })(); |
| } |
| |
| /// The equivalent of [compare_predicate_entailment], but for associated types |
| /// instead of associated functions. |
| fn compare_type_predicate_entailment<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_ty: &ty::AssocItem, |
| impl_ty_span: Span, |
| trait_ty: &ty::AssocItem, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| ) -> Result<(), ErrorGuaranteed> { |
| let impl_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); |
| let trait_to_impl_substs = |
| impl_substs.rebase_onto(tcx, impl_ty.container_id(tcx), impl_trait_ref.substs); |
| |
| let impl_ty_generics = tcx.generics_of(impl_ty.def_id); |
| let trait_ty_generics = tcx.generics_of(trait_ty.def_id); |
| let impl_ty_predicates = tcx.predicates_of(impl_ty.def_id); |
| let trait_ty_predicates = tcx.predicates_of(trait_ty.def_id); |
| |
| check_region_bounds_on_impl_item( |
| tcx, |
| impl_ty, |
| trait_ty, |
| &trait_ty_generics, |
| &impl_ty_generics, |
| )?; |
| |
| let impl_ty_own_bounds = impl_ty_predicates.instantiate_own(tcx, impl_substs); |
| |
| if impl_ty_own_bounds.is_empty() { |
| // Nothing to check. |
| return Ok(()); |
| } |
| |
| // This `HirId` should be used for the `body_id` field on each |
| // `ObligationCause` (and the `FnCtxt`). This is what |
| // `regionck_item` expects. |
| let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
| debug!("compare_type_predicate_entailment: trait_to_impl_substs={:?}", trait_to_impl_substs); |
| |
| // The predicates declared by the impl definition, the trait and the |
| // associated type in the trait are assumed. |
| let impl_predicates = tcx.predicates_of(impl_ty_predicates.parent.unwrap()); |
| let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); |
| hybrid_preds |
| .predicates |
| .extend(trait_ty_predicates.instantiate_own(tcx, trait_to_impl_substs).predicates); |
| |
| debug!("compare_type_predicate_entailment: bounds={:?}", hybrid_preds); |
| |
| let normalize_cause = traits::ObligationCause::misc(impl_ty_span, impl_ty_hir_id); |
| let param_env = ty::ParamEnv::new( |
| tcx.intern_predicates(&hybrid_preds.predicates), |
| Reveal::UserFacing, |
| hir::Constness::NotConst, |
| ); |
| let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause); |
| let infcx = tcx.infer_ctxt().build(); |
| let ocx = ObligationCtxt::new(&infcx); |
| |
| debug!("compare_type_predicate_entailment: caller_bounds={:?}", param_env.caller_bounds()); |
| |
| let mut selcx = traits::SelectionContext::new(&infcx); |
| |
| assert_eq!(impl_ty_own_bounds.predicates.len(), impl_ty_own_bounds.spans.len()); |
| for (span, predicate) in std::iter::zip(impl_ty_own_bounds.spans, impl_ty_own_bounds.predicates) |
| { |
| let cause = ObligationCause::misc(span, impl_ty_hir_id); |
| let traits::Normalized { value: predicate, obligations } = |
| traits::normalize(&mut selcx, param_env, cause, predicate); |
| |
| let cause = ObligationCause::new( |
| span, |
| impl_ty_hir_id, |
| ObligationCauseCode::CompareImplItemObligation { |
| impl_item_def_id: impl_ty.def_id.expect_local(), |
| trait_item_def_id: trait_ty.def_id, |
| kind: impl_ty.kind, |
| }, |
| ); |
| ocx.register_obligations(obligations); |
| ocx.register_obligation(traits::Obligation::new(cause, param_env, predicate)); |
| } |
| |
| // Check that all obligations are satisfied by the implementation's |
| // version. |
| let errors = ocx.select_all_or_error(); |
| if !errors.is_empty() { |
| let reported = infcx.err_ctxt().report_fulfillment_errors(&errors, None, false); |
| return Err(reported); |
| } |
| |
| // Finally, resolve all regions. This catches wily misuses of |
| // lifetime parameters. |
| let outlives_environment = OutlivesEnvironment::new(param_env); |
| infcx.check_region_obligations_and_report_errors( |
| impl_ty.def_id.expect_local(), |
| &outlives_environment, |
| ); |
| |
| Ok(()) |
| } |
| |
| /// Validate that `ProjectionCandidate`s created for this associated type will |
| /// be valid. |
| /// |
| /// Usually given |
| /// |
| /// trait X { type Y: Copy } impl X for T { type Y = S; } |
| /// |
| /// We are able to normalize `<T as X>::U` to `S`, and so when we check the |
| /// impl is well-formed we have to prove `S: Copy`. |
| /// |
| /// For default associated types the normalization is not possible (the value |
| /// from the impl could be overridden). We also can't normalize generic |
| /// associated types (yet) because they contain bound parameters. |
| #[instrument(level = "debug", skip(tcx))] |
| pub fn check_type_bounds<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| trait_ty: &ty::AssocItem, |
| impl_ty: &ty::AssocItem, |
| impl_ty_span: Span, |
| impl_trait_ref: ty::TraitRef<'tcx>, |
| ) -> Result<(), ErrorGuaranteed> { |
| // Given |
| // |
| // impl<A, B> Foo<u32> for (A, B) { |
| // type Bar<C> =... |
| // } |
| // |
| // - `impl_trait_ref` would be `<(A, B) as Foo<u32>> |
| // - `impl_ty_substs` would be `[A, B, ^0.0]` (`^0.0` here is the bound var with db 0 and index 0) |
| // - `rebased_substs` would be `[(A, B), u32, ^0.0]`, combining the substs from |
| // the *trait* with the generic associated type parameters (as bound vars). |
| // |
| // A note regarding the use of bound vars here: |
| // Imagine as an example |
| // ``` |
| // trait Family { |
| // type Member<C: Eq>; |
| // } |
| // |
| // impl Family for VecFamily { |
| // type Member<C: Eq> = i32; |
| // } |
| // ``` |
| // Here, we would generate |
| // ```notrust |
| // forall<C> { Normalize(<VecFamily as Family>::Member<C> => i32) } |
| // ``` |
| // when we really would like to generate |
| // ```notrust |
| // forall<C> { Normalize(<VecFamily as Family>::Member<C> => i32) :- Implemented(C: Eq) } |
| // ``` |
| // But, this is probably fine, because although the first clause can be used with types C that |
| // do not implement Eq, for it to cause some kind of problem, there would have to be a |
| // VecFamily::Member<X> for some type X where !(X: Eq), that appears in the value of type |
| // Member<C: Eq> = .... That type would fail a well-formedness check that we ought to be doing |
| // elsewhere, which would check that any <T as Family>::Member<X> meets the bounds declared in |
| // the trait (notably, that X: Eq and T: Family). |
| let defs: &ty::Generics = tcx.generics_of(impl_ty.def_id); |
| let mut substs = smallvec::SmallVec::with_capacity(defs.count()); |
| if let Some(def_id) = defs.parent { |
| let parent_defs = tcx.generics_of(def_id); |
| InternalSubsts::fill_item(&mut substs, tcx, parent_defs, &mut |param, _| { |
| tcx.mk_param_from_def(param) |
| }); |
| } |
| let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> = |
| smallvec::SmallVec::with_capacity(defs.count()); |
| InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param.kind { |
| GenericParamDefKind::Type { .. } => { |
| let kind = ty::BoundTyKind::Param(param.name); |
| let bound_var = ty::BoundVariableKind::Ty(kind); |
| bound_vars.push(bound_var); |
| tcx.mk_ty(ty::Bound( |
| ty::INNERMOST, |
| ty::BoundTy { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, |
| )) |
| .into() |
| } |
| GenericParamDefKind::Lifetime => { |
| let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name); |
| let bound_var = ty::BoundVariableKind::Region(kind); |
| bound_vars.push(bound_var); |
| tcx.mk_region(ty::ReLateBound( |
| ty::INNERMOST, |
| ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, |
| )) |
| .into() |
| } |
| GenericParamDefKind::Const { .. } => { |
| let bound_var = ty::BoundVariableKind::Const; |
| bound_vars.push(bound_var); |
| tcx.mk_const(ty::ConstS { |
| ty: tcx.type_of(param.def_id), |
| kind: ty::ConstKind::Bound( |
| ty::INNERMOST, |
| ty::BoundVar::from_usize(bound_vars.len() - 1), |
| ), |
| }) |
| .into() |
| } |
| }); |
| let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter()); |
| let impl_ty_substs = tcx.intern_substs(&substs); |
| let container_id = impl_ty.container_id(tcx); |
| |
| let rebased_substs = impl_ty_substs.rebase_onto(tcx, container_id, impl_trait_ref.substs); |
| let impl_ty_value = tcx.type_of(impl_ty.def_id); |
| |
| let param_env = tcx.param_env(impl_ty.def_id); |
| |
| // When checking something like |
| // |
| // trait X { type Y: PartialEq<<Self as X>::Y> } |
| // impl X for T { default type Y = S; } |
| // |
| // We will have to prove the bound S: PartialEq<<T as X>::Y>. In this case |
| // we want <T as X>::Y to normalize to S. This is valid because we are |
| // checking the default value specifically here. Add this equality to the |
| // ParamEnv for normalization specifically. |
| let normalize_param_env = { |
| let mut predicates = param_env.caller_bounds().iter().collect::<Vec<_>>(); |
| match impl_ty_value.kind() { |
| ty::Projection(proj) |
| if proj.item_def_id == trait_ty.def_id && proj.substs == rebased_substs => |
| { |
| // Don't include this predicate if the projected type is |
| // exactly the same as the projection. This can occur in |
| // (somewhat dubious) code like this: |
| // |
| // impl<T> X for T where T: X { type Y = <T as X>::Y; } |
| } |
| _ => predicates.push( |
| ty::Binder::bind_with_vars( |
| ty::ProjectionPredicate { |
| projection_ty: ty::ProjectionTy { |
| item_def_id: trait_ty.def_id, |
| substs: rebased_substs, |
| }, |
| term: impl_ty_value.into(), |
| }, |
| bound_vars, |
| ) |
| .to_predicate(tcx), |
| ), |
| }; |
| ty::ParamEnv::new( |
| tcx.intern_predicates(&predicates), |
| Reveal::UserFacing, |
| param_env.constness(), |
| ) |
| }; |
| debug!(?normalize_param_env); |
| |
| let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
| let impl_ty_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); |
| let rebased_substs = impl_ty_substs.rebase_onto(tcx, container_id, impl_trait_ref.substs); |
| |
| let infcx = tcx.infer_ctxt().build(); |
| let ocx = ObligationCtxt::new(&infcx); |
| |
| let assumed_wf_types = |
| ocx.assumed_wf_types(param_env, impl_ty_span, impl_ty.def_id.expect_local()); |
| |
| let mut selcx = traits::SelectionContext::new(&infcx); |
| let normalize_cause = ObligationCause::new( |
| impl_ty_span, |
| impl_ty_hir_id, |
| ObligationCauseCode::CheckAssociatedTypeBounds { |
| impl_item_def_id: impl_ty.def_id.expect_local(), |
| trait_item_def_id: trait_ty.def_id, |
| }, |
| ); |
| let mk_cause = |span: Span| { |
| let code = if span.is_dummy() { |
| traits::ItemObligation(trait_ty.def_id) |
| } else { |
| traits::BindingObligation(trait_ty.def_id, span) |
| }; |
| ObligationCause::new(impl_ty_span, impl_ty_hir_id, code) |
| }; |
| |
| let obligations = tcx |
| .bound_explicit_item_bounds(trait_ty.def_id) |
| .subst_iter_copied(tcx, rebased_substs) |
| .map(|(concrete_ty_bound, span)| { |
| debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound); |
| traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound) |
| }) |
| .collect(); |
| debug!("check_type_bounds: item_bounds={:?}", obligations); |
| |
| for mut obligation in util::elaborate_obligations(tcx, obligations) { |
| let traits::Normalized { value: normalized_predicate, obligations } = traits::normalize( |
| &mut selcx, |
| normalize_param_env, |
| normalize_cause.clone(), |
| obligation.predicate, |
| ); |
| debug!("compare_projection_bounds: normalized predicate = {:?}", normalized_predicate); |
| obligation.predicate = normalized_predicate; |
| |
| ocx.register_obligations(obligations); |
| ocx.register_obligation(obligation); |
| } |
| // Check that all obligations are satisfied by the implementation's |
| // version. |
| let errors = ocx.select_all_or_error(); |
| if !errors.is_empty() { |
| let reported = infcx.err_ctxt().report_fulfillment_errors(&errors, None, false); |
| return Err(reported); |
| } |
| |
| // Finally, resolve all regions. This catches wily misuses of |
| // lifetime parameters. |
| let implied_bounds = infcx.implied_bounds_tys(param_env, impl_ty_hir_id, assumed_wf_types); |
| let outlives_environment = |
| OutlivesEnvironment::with_bounds(param_env, Some(&infcx), implied_bounds); |
| |
| infcx.check_region_obligations_and_report_errors( |
| impl_ty.def_id.expect_local(), |
| &outlives_environment, |
| ); |
| |
| let constraints = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types(); |
| for (key, value) in constraints { |
| infcx |
| .err_ctxt() |
| .report_mismatched_types( |
| &ObligationCause::misc( |
| value.hidden_type.span, |
| tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()), |
| ), |
| tcx.mk_opaque(key.def_id.to_def_id(), key.substs), |
| value.hidden_type.ty, |
| TypeError::Mismatch, |
| ) |
| .emit(); |
| } |
| |
| Ok(()) |
| } |
| |
| fn assoc_item_kind_str(impl_item: &ty::AssocItem) -> &'static str { |
| match impl_item.kind { |
| ty::AssocKind::Const => "const", |
| ty::AssocKind::Fn => "method", |
| ty::AssocKind::Type => "type", |
| } |
| } |
