diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/project.rs')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/project.rs | 170 |
1 files changed, 100 insertions, 70 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs index dd868c9d40e..ca58da5ca6d 100644 --- a/compiler/rustc_trait_selection/src/traits/project.rs +++ b/compiler/rustc_trait_selection/src/traits/project.rs @@ -5,7 +5,6 @@ use std::ops::ControlFlow; use rustc_data_structures::sso::SsoHashSet; use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_errors::ErrorGuaranteed; -use rustc_hir::def::DefKind; use rustc_hir::lang_items::LangItem; use rustc_infer::infer::DefineOpaqueTypes; use rustc_infer::infer::resolve::OpportunisticRegionResolver; @@ -172,6 +171,7 @@ pub(super) enum ProjectAndUnifyResult<'tcx> { /// ``` /// If successful, this may result in additional obligations. Also returns /// the projection cache key used to track these additional obligations. +// FIXME(mgca): While this supports constants, it is only used for types by default right now #[instrument(level = "debug", skip(selcx))] pub(super) fn poly_project_and_unify_term<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, @@ -201,6 +201,7 @@ pub(super) fn poly_project_and_unify_term<'cx, 'tcx>( /// If successful, this may result in additional obligations. /// /// See [poly_project_and_unify_term] for an explanation of the return value. +// FIXME(mgca): While this supports constants, it is only used for types by default right now #[instrument(level = "debug", skip(selcx))] fn project_and_unify_term<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, @@ -258,34 +259,28 @@ fn project_and_unify_term<'cx, 'tcx>( /// there are unresolved type variables in the projection, we will /// instantiate it with a fresh type variable `$X` and generate a new /// obligation `<T as Trait>::Item == $X` for later. -pub fn normalize_projection_ty<'a, 'b, 'tcx>( +// FIXME(mgca): While this supports constants, it is only used for types by default right now +pub fn normalize_projection_term<'a, 'b, 'tcx>( selcx: &'a mut SelectionContext<'b, 'tcx>, param_env: ty::ParamEnv<'tcx>, - projection_ty: ty::AliasTy<'tcx>, + alias_term: ty::AliasTerm<'tcx>, cause: ObligationCause<'tcx>, depth: usize, obligations: &mut PredicateObligations<'tcx>, ) -> Term<'tcx> { - opt_normalize_projection_term( - selcx, - param_env, - projection_ty.into(), - cause.clone(), - depth, - obligations, - ) - .ok() - .flatten() - .unwrap_or_else(move || { - // if we bottom out in ambiguity, create a type variable - // and a deferred predicate to resolve this when more type - // information is available. - - selcx - .infcx - .projection_ty_to_infer(param_env, projection_ty, cause, depth + 1, obligations) - .into() - }) + opt_normalize_projection_term(selcx, param_env, alias_term, cause.clone(), depth, obligations) + .ok() + .flatten() + .unwrap_or_else(move || { + // if we bottom out in ambiguity, create a type variable + // and a deferred predicate to resolve this when more type + // information is available. + + selcx + .infcx + .projection_term_to_infer(param_env, alias_term, cause, depth + 1, obligations) + .into() + }) } /// The guts of `normalize`: normalize a specific projection like `<T @@ -298,6 +293,7 @@ pub fn normalize_projection_ty<'a, 'b, 'tcx>( /// often immediately appended to another obligations vector. So now this /// function takes an obligations vector and appends to it directly, which is /// slightly uglier but avoids the need for an extra short-lived allocation. +// FIXME(mgca): While this supports constants, it is only used for types by default right now #[instrument(level = "debug", skip(selcx, param_env, cause, obligations))] pub(super) fn opt_normalize_projection_term<'a, 'b, 'tcx>( selcx: &'a mut SelectionContext<'b, 'tcx>, @@ -456,6 +452,7 @@ pub(super) fn opt_normalize_projection_term<'a, 'b, 'tcx>( /// an error for this obligation, but we legitimately should not, /// because it contains `[type error]`. Yuck! (See issue #29857 for /// one case where this arose.) +// FIXME(mgca): While this supports constants, it is only used for types by default right now fn normalize_to_error<'a, 'tcx>( selcx: &SelectionContext<'a, 'tcx>, param_env: ty::ParamEnv<'tcx>, @@ -469,9 +466,10 @@ fn normalize_to_error<'a, 'tcx>( | ty::AliasTermKind::InherentTy | ty::AliasTermKind::OpaqueTy | ty::AliasTermKind::FreeTy => selcx.infcx.next_ty_var(cause.span).into(), - ty::AliasTermKind::UnevaluatedConst | ty::AliasTermKind::ProjectionConst => { - selcx.infcx.next_const_var(cause.span).into() - } + ty::AliasTermKind::FreeConst + | ty::AliasTermKind::InherentConst + | ty::AliasTermKind::UnevaluatedConst + | ty::AliasTermKind::ProjectionConst => selcx.infcx.next_const_var(cause.span).into(), }; let mut obligations = PredicateObligations::new(); obligations.push(Obligation { @@ -484,36 +482,37 @@ fn normalize_to_error<'a, 'tcx>( } /// Confirm and normalize the given inherent projection. +// FIXME(mgca): While this supports constants, it is only used for types by default right now #[instrument(level = "debug", skip(selcx, param_env, cause, obligations))] pub fn normalize_inherent_projection<'a, 'b, 'tcx>( selcx: &'a mut SelectionContext<'b, 'tcx>, param_env: ty::ParamEnv<'tcx>, - alias_ty: ty::AliasTy<'tcx>, + alias_term: ty::AliasTerm<'tcx>, cause: ObligationCause<'tcx>, depth: usize, obligations: &mut PredicateObligations<'tcx>, -) -> Ty<'tcx> { +) -> ty::Term<'tcx> { let tcx = selcx.tcx(); if !tcx.recursion_limit().value_within_limit(depth) { // Halt compilation because it is important that overflows never be masked. tcx.dcx().emit_fatal(InherentProjectionNormalizationOverflow { span: cause.span, - ty: alias_ty.to_string(), + ty: alias_term.to_string(), }); } - let args = compute_inherent_assoc_ty_args( + let args = compute_inherent_assoc_term_args( selcx, param_env, - alias_ty, + alias_term, cause.clone(), depth, obligations, ); // Register the obligations arising from the impl and from the associated type itself. - let predicates = tcx.predicates_of(alias_ty.def_id).instantiate(tcx, args); + let predicates = tcx.predicates_of(alias_term.def_id).instantiate(tcx, args); for (predicate, span) in predicates { let predicate = normalize_with_depth_to( selcx, @@ -531,7 +530,7 @@ pub fn normalize_inherent_projection<'a, 'b, 'tcx>( // cause code, inherent projections will be printed with identity instantiation in // diagnostics which is not ideal. // Consider creating separate cause codes for this specific situation. - ObligationCauseCode::WhereClause(alias_ty.def_id, span), + ObligationCauseCode::WhereClause(alias_term.def_id, span), ); obligations.push(Obligation::with_depth( @@ -543,27 +542,33 @@ pub fn normalize_inherent_projection<'a, 'b, 'tcx>( )); } - let ty = tcx.type_of(alias_ty.def_id).instantiate(tcx, args); + let term: Term<'tcx> = if alias_term.kind(tcx).is_type() { + tcx.type_of(alias_term.def_id).instantiate(tcx, args).into() + } else { + get_associated_const_value(selcx, alias_term.to_term(tcx).expect_const(), param_env).into() + }; - let mut ty = selcx.infcx.resolve_vars_if_possible(ty); - if ty.has_aliases() { - ty = normalize_with_depth_to(selcx, param_env, cause.clone(), depth + 1, ty, obligations); + let mut term = selcx.infcx.resolve_vars_if_possible(term); + if term.has_aliases() { + term = + normalize_with_depth_to(selcx, param_env, cause.clone(), depth + 1, term, obligations); } - ty + term } -pub fn compute_inherent_assoc_ty_args<'a, 'b, 'tcx>( +// FIXME(mgca): While this supports constants, it is only used for types by default right now +pub fn compute_inherent_assoc_term_args<'a, 'b, 'tcx>( selcx: &'a mut SelectionContext<'b, 'tcx>, param_env: ty::ParamEnv<'tcx>, - alias_ty: ty::AliasTy<'tcx>, + alias_term: ty::AliasTerm<'tcx>, cause: ObligationCause<'tcx>, depth: usize, obligations: &mut PredicateObligations<'tcx>, ) -> ty::GenericArgsRef<'tcx> { let tcx = selcx.tcx(); - let impl_def_id = tcx.parent(alias_ty.def_id); + let impl_def_id = tcx.parent(alias_term.def_id); let impl_args = selcx.infcx.fresh_args_for_item(cause.span, impl_def_id); let mut impl_ty = tcx.type_of(impl_def_id).instantiate(tcx, impl_args); @@ -580,7 +585,7 @@ pub fn compute_inherent_assoc_ty_args<'a, 'b, 'tcx>( // Infer the generic parameters of the impl by unifying the // impl type with the self type of the projection. - let mut self_ty = alias_ty.self_ty(); + let mut self_ty = alias_term.self_ty(); if !selcx.infcx.next_trait_solver() { self_ty = normalize_with_depth_to( selcx, @@ -602,7 +607,7 @@ pub fn compute_inherent_assoc_ty_args<'a, 'b, 'tcx>( } } - alias_ty.rebase_inherent_args_onto_impl(impl_args, tcx) + alias_term.rebase_inherent_args_onto_impl(impl_args, tcx) } enum Projected<'tcx> { @@ -630,6 +635,7 @@ impl<'tcx> Progress<'tcx> { /// /// IMPORTANT: /// - `obligation` must be fully normalized +// FIXME(mgca): While this supports constants, it is only used for types by default right now #[instrument(level = "info", skip(selcx))] fn project<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, @@ -896,7 +902,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>( ImplSource::UserDefined(impl_data) => { // We have to be careful when projecting out of an // impl because of specialization. If we are not in - // codegen (i.e., projection mode is not "any"), and the + // codegen (i.e., `TypingMode` is not `PostAnalysis`), and the // impl's type is declared as default, then we disable // projection (even if the trait ref is fully // monomorphic). In the case where trait ref is not @@ -1189,6 +1195,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>( }); } +// FIXME(mgca): While this supports constants, it is only used for types by default right now fn confirm_candidate<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, obligation: &ProjectionTermObligation<'tcx>, @@ -1222,6 +1229,7 @@ fn confirm_candidate<'cx, 'tcx>( result } +// FIXME(mgca): While this supports constants, it is only used for types by default right now fn confirm_select_candidate<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, obligation: &ProjectionTermObligation<'tcx>, @@ -1873,6 +1881,7 @@ fn confirm_async_fn_kind_helper_candidate<'cx, 'tcx>( .with_addl_obligations(nested) } +// FIXME(mgca): While this supports constants, it is only used for types by default right now fn confirm_param_env_candidate<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, obligation: &ProjectionTermObligation<'tcx>, @@ -1926,9 +1935,7 @@ fn confirm_param_env_candidate<'cx, 'tcx>( ) { Ok(InferOk { value: _, obligations }) => { nested_obligations.extend(obligations); - assoc_ty_own_obligations(selcx, obligation, &mut nested_obligations); - // FIXME(associated_const_equality): Handle consts here as well? Maybe this progress type should just take - // a term instead. + assoc_term_own_obligations(selcx, obligation, &mut nested_obligations); Progress { term: cache_entry.term, obligations: nested_obligations } } Err(e) => { @@ -1942,6 +1949,7 @@ fn confirm_param_env_candidate<'cx, 'tcx>( } } +// FIXME(mgca): While this supports constants, it is only used for types by default right now fn confirm_impl_candidate<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, obligation: &ProjectionTermObligation<'tcx>, @@ -1955,8 +1963,8 @@ fn confirm_impl_candidate<'cx, 'tcx>( let trait_def_id = tcx.trait_id_of_impl(impl_def_id).unwrap(); let param_env = obligation.param_env; - let assoc_ty = match specialization_graph::assoc_def(tcx, impl_def_id, assoc_item_id) { - Ok(assoc_ty) => assoc_ty, + let assoc_term = match specialization_graph::assoc_def(tcx, impl_def_id, assoc_item_id) { + Ok(assoc_term) => assoc_term, Err(guar) => return Ok(Projected::Progress(Progress::error(tcx, guar))), }; @@ -1965,10 +1973,10 @@ fn confirm_impl_candidate<'cx, 'tcx>( // has impossible-to-satisfy predicates (since those were // allowed in <https://github.com/rust-lang/rust/pull/135480>), // or because the impl is literally missing the definition. - if !assoc_ty.item.defaultness(tcx).has_value() { + if !assoc_term.item.defaultness(tcx).has_value() { debug!( "confirm_impl_candidate: no associated type {:?} for {:?}", - assoc_ty.item.name(), + assoc_term.item.name(), obligation.predicate ); if tcx.impl_self_is_guaranteed_unsized(impl_def_id) { @@ -1979,7 +1987,11 @@ fn confirm_impl_candidate<'cx, 'tcx>( return Ok(Projected::NoProgress(obligation.predicate.to_term(tcx))); } else { return Ok(Projected::Progress(Progress { - term: Ty::new_misc_error(tcx).into(), + term: if obligation.predicate.kind(tcx).is_type() { + Ty::new_misc_error(tcx).into() + } else { + ty::Const::new_misc_error(tcx).into() + }, obligations: nested, })); } @@ -1992,27 +2004,32 @@ fn confirm_impl_candidate<'cx, 'tcx>( // * `args` is `[u32]` // * `args` ends up as `[u32, S]` let args = obligation.predicate.args.rebase_onto(tcx, trait_def_id, args); - let args = translate_args(selcx.infcx, param_env, impl_def_id, args, assoc_ty.defining_node); - let is_const = matches!(tcx.def_kind(assoc_ty.item.def_id), DefKind::AssocConst); - - let term: ty::EarlyBinder<'tcx, ty::Term<'tcx>> = if is_const { - let did = assoc_ty.item.def_id; - let identity_args = crate::traits::GenericArgs::identity_for_item(tcx, did); - let uv = ty::UnevaluatedConst::new(did, identity_args); - ty::EarlyBinder::bind(ty::Const::new_unevaluated(tcx, uv).into()) + let args = translate_args(selcx.infcx, param_env, impl_def_id, args, assoc_term.defining_node); + + let term = if obligation.predicate.kind(tcx).is_type() { + tcx.type_of(assoc_term.item.def_id).map_bound(|ty| ty.into()) } else { - tcx.type_of(assoc_ty.item.def_id).map_bound(|ty| ty.into()) + ty::EarlyBinder::bind( + get_associated_const_value( + selcx, + obligation.predicate.to_term(tcx).expect_const(), + param_env, + ) + .into(), + ) }; - let progress = if !tcx.check_args_compatible(assoc_ty.item.def_id, args) { - let err = Ty::new_error_with_message( - tcx, - obligation.cause.span, - "impl item and trait item have different parameters", - ); - Progress { term: err.into(), obligations: nested } + let progress = if !tcx.check_args_compatible(assoc_term.item.def_id, args) { + let msg = "impl item and trait item have different parameters"; + let span = obligation.cause.span; + let err = if obligation.predicate.kind(tcx).is_type() { + Ty::new_error_with_message(tcx, span, msg).into() + } else { + ty::Const::new_error_with_message(tcx, span, msg).into() + }; + Progress { term: err, obligations: nested } } else { - assoc_ty_own_obligations(selcx, obligation, &mut nested); + assoc_term_own_obligations(selcx, obligation, &mut nested); Progress { term: term.instantiate(tcx, args), obligations: nested } }; Ok(Projected::Progress(progress)) @@ -2020,7 +2037,8 @@ fn confirm_impl_candidate<'cx, 'tcx>( // Get obligations corresponding to the predicates from the where-clause of the // associated type itself. -fn assoc_ty_own_obligations<'cx, 'tcx>( +// FIXME(mgca): While this supports constants, it is only used for types by default right now +fn assoc_term_own_obligations<'cx, 'tcx>( selcx: &mut SelectionContext<'cx, 'tcx>, obligation: &ProjectionTermObligation<'tcx>, nested: &mut PredicateObligations<'tcx>, @@ -2090,3 +2108,15 @@ impl<'cx, 'tcx> ProjectionCacheKeyExt<'cx, 'tcx> for ProjectionCacheKey<'tcx> { }) } } + +fn get_associated_const_value<'tcx>( + selcx: &mut SelectionContext<'_, 'tcx>, + alias_ct: ty::Const<'tcx>, + param_env: ty::ParamEnv<'tcx>, +) -> ty::Const<'tcx> { + // FIXME(mgca): We shouldn't be invoking ctfe here, instead const items should be aliases to type + // system consts that we can retrieve with some `query const_arg_of_alias` query. Evaluating the + // constant is "close enough" to getting the actual rhs of the const item for now even if it might + // lead to some cycles + super::evaluate_const(selcx.infcx, alias_ct, param_env) +} |