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Diffstat (limited to '')
| -rw-r--r-- | compiler/rustc_typeck/src/check/compare_method.rs | 1547 |
1 files changed, 0 insertions, 1547 deletions
diff --git a/compiler/rustc_typeck/src/check/compare_method.rs b/compiler/rustc_typeck/src/check/compare_method.rs deleted file mode 100644 index 666498403..000000000 --- a/compiler/rustc_typeck/src/check/compare_method.rs +++ /dev/null @@ -1,1547 +0,0 @@ -use super::potentially_plural_count; -use crate::check::regionck::OutlivesEnvironmentExt; -use crate::check::wfcheck; -use crate::errors::LifetimesOrBoundsMismatchOnTrait; -use rustc_data_structures::fx::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::{self, TyCtxtInferExt}; -use rustc_infer::traits::util; -use rustc_middle::ty::error::{ExpectedFound, TypeError}; -use rustc_middle::ty::subst::{InternalSubsts, Subst}; -use rustc_middle::ty::util::ExplicitSelf; -use rustc_middle::ty::{self, DefIdTree}; -use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt}; -use rustc_span::Span; -use rustc_trait_selection::traits::error_reporting::InferCtxtExt; -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; - } -} - -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<(), 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, - }, - ); - - // 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_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 in - // a fresh FulfillmentCtxt, and invoke select_all_or_error. - - // 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); - - tcx.infer_ctxt().enter(|ref infcx| { - 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); - let trait_sig = ocx.normalize(norm_cause, param_env, trait_sig); - // Add the resulting inputs and output as well-formed. - 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 sub_result = infcx - .at(&cause, param_env) - .sup(trait_fty, impl_fty) - .map(|infer_ok| ocx.register_infer_ok_obligations(infer_ok)); - - 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, &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.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.report_fulfillment_errors(&errors, None, false); - return Err(reported); - } - - // Finally, resolve all regions. This catches wily misuses of - // lifetime parameters. - let mut outlives_environment = OutlivesEnvironment::new(param_env); - outlives_environment.add_implied_bounds(infcx, wf_tys, impl_m_hir_id); - infcx.check_region_obligations_and_report_errors( - impl_m.def_id.expect_local(), - &outlives_environment, - ); - - Ok(()) - }) -} - -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<'a, 'tcx>( - infcx: &infer::InferCtxt<'a, '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(); - - tcx.infer_ctxt().enter(|infcx| { - 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_hir_id = tcx.hir().local_def_id_to_hir_id(impl_def_id); - 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.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.sess.source_map().span_to_snippet(trait_span).ok()?; - let trait_m = trait_m.def_id.as_local()?; - let trait_m = tcx.hir().trait_item(hir::TraitItemId { def_id: trait_m }); - - let impl_m = impl_m.def_id.as_local()?; - let impl_m = tcx.hir().impl_item(hir::ImplItemId { def_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. - (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().impl_item(hir::ImplItemId { def_id: 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(()) -} - -pub(crate) 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 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_c.def_id.expect_local()); - - // Compute placeholder form of impl and trait const tys. - let impl_ty = tcx.type_of(impl_c.def_id); - let trait_ty = tcx.bound_type_of(trait_c.def_id).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_c.def_id.expect_local(), - trait_item_def_id: trait_c.def_id, - kind: impl_c.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_c.def_id.expect_local()).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.name - ); - - let trait_c_span = trait_c.def_id.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_c), - } - }); - - infcx.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, - ); - diag.emit(); - } - - // Check that all obligations are satisfied by the implementation's - // version. - let errors = ocx.select_all_or_error(); - if !errors.is_empty() { - infcx.report_fulfillment_errors(&errors, None, false); - return; - } - - let outlives_environment = OutlivesEnvironment::new(param_env); - infcx.check_region_obligations_and_report_errors( - impl_c.def_id.expect_local(), - &outlives_environment, - ); - }); -} - -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); - tcx.infer_ctxt().enter(|infcx| { - 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.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. -#[tracing::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_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); - - tcx.infer_ctxt().enter(move |infcx| { - let ocx = ObligationCtxt::new(&infcx); - - let mut selcx = traits::SelectionContext::new(&infcx); - let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); - 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::MiscObligation - } 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) - .transpose_iter() - .map(|e| e.map_bound(|e| *e).transpose_tuple2()) - .map(|(bound, span)| { - debug!(?bound); - // this is where opaque type is found - let concrete_ty_bound = bound.subst(tcx, rebased_substs); - debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound); - - traits::Obligation::new(mk_cause(span.0), 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.report_fulfillment_errors(&errors, None, false); - return Err(reported); - } - - // Finally, resolve all regions. This catches wily misuses of - // lifetime parameters. - let implied_bounds = match impl_ty.container { - ty::TraitContainer => FxHashSet::default(), - ty::ImplContainer => wfcheck::impl_implied_bounds( - tcx, - param_env, - container_id.expect_local(), - impl_ty_span, - ), - }; - let mut outlives_environment = OutlivesEnvironment::new(param_env); - outlives_environment.add_implied_bounds(&infcx, implied_bounds, impl_ty_hir_id); - 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 - .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", - } -} |