| //! Generalized type relating mechanism. |
| //! |
| //! A type relation `R` relates a pair of values `(A, B)`. `A and B` are usually |
| //! types or regions but can be other things. Examples of type relations are |
| //! subtyping, type equality, etc. |
| |
| use crate::ty::error::{ExpectedFound, TypeError}; |
| use crate::ty::{self, Expr, ImplSubject, Term, TermKind, Ty, TyCtxt, TypeFoldable}; |
| use crate::ty::{GenericArg, GenericArgKind, GenericArgsRef}; |
| use rustc_hir as hir; |
| use rustc_hir::def::DefKind; |
| use rustc_hir::def_id::DefId; |
| use rustc_target::spec::abi; |
| use std::iter; |
| |
| pub type RelateResult<'tcx, T> = Result<T, TypeError<'tcx>>; |
| |
| #[derive(Clone, Debug)] |
| pub enum Cause { |
| ExistentialRegionBound, // relating an existential region bound |
| } |
| |
| pub trait TypeRelation<'tcx>: Sized { |
| fn tcx(&self) -> TyCtxt<'tcx>; |
| |
| fn param_env(&self) -> ty::ParamEnv<'tcx>; |
| |
| /// Returns a static string we can use for printouts. |
| fn tag(&self) -> &'static str; |
| |
| /// Returns `true` if the value `a` is the "expected" type in the |
| /// relation. Just affects error messages. |
| fn a_is_expected(&self) -> bool; |
| |
| fn with_cause<F, R>(&mut self, _cause: Cause, f: F) -> R |
| where |
| F: FnOnce(&mut Self) -> R, |
| { |
| f(self) |
| } |
| |
| /// Generic relation routine suitable for most anything. |
| fn relate<T: Relate<'tcx>>(&mut self, a: T, b: T) -> RelateResult<'tcx, T> { |
| Relate::relate(self, a, b) |
| } |
| |
| /// Relate the two args for the given item. The default |
| /// is to look up the variance for the item and proceed |
| /// accordingly. |
| fn relate_item_args( |
| &mut self, |
| item_def_id: DefId, |
| a_arg: GenericArgsRef<'tcx>, |
| b_arg: GenericArgsRef<'tcx>, |
| ) -> RelateResult<'tcx, GenericArgsRef<'tcx>> { |
| debug!( |
| "relate_item_args(item_def_id={:?}, a_arg={:?}, b_arg={:?})", |
| item_def_id, a_arg, b_arg |
| ); |
| |
| let tcx = self.tcx(); |
| let opt_variances = tcx.variances_of(item_def_id); |
| relate_args_with_variances(self, item_def_id, opt_variances, a_arg, b_arg, true) |
| } |
| |
| /// Switch variance for the purpose of relating `a` and `b`. |
| fn relate_with_variance<T: Relate<'tcx>>( |
| &mut self, |
| variance: ty::Variance, |
| info: ty::VarianceDiagInfo<'tcx>, |
| a: T, |
| b: T, |
| ) -> RelateResult<'tcx, T>; |
| |
| // Overridable relations. You shouldn't typically call these |
| // directly, instead call `relate()`, which in turn calls |
| // these. This is both more uniform but also allows us to add |
| // additional hooks for other types in the future if needed |
| // without making older code, which called `relate`, obsolete. |
| |
| fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>>; |
| |
| fn regions( |
| &mut self, |
| a: ty::Region<'tcx>, |
| b: ty::Region<'tcx>, |
| ) -> RelateResult<'tcx, ty::Region<'tcx>>; |
| |
| fn consts( |
| &mut self, |
| a: ty::Const<'tcx>, |
| b: ty::Const<'tcx>, |
| ) -> RelateResult<'tcx, ty::Const<'tcx>>; |
| |
| fn binders<T>( |
| &mut self, |
| a: ty::Binder<'tcx, T>, |
| b: ty::Binder<'tcx, T>, |
| ) -> RelateResult<'tcx, ty::Binder<'tcx, T>> |
| where |
| T: Relate<'tcx>; |
| } |
| |
| pub trait Relate<'tcx>: TypeFoldable<TyCtxt<'tcx>> + PartialEq + Copy { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: Self, |
| b: Self, |
| ) -> RelateResult<'tcx, Self>; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Relate impls |
| |
| pub fn relate_type_and_mut<'tcx, R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::TypeAndMut<'tcx>, |
| b: ty::TypeAndMut<'tcx>, |
| base_ty: Ty<'tcx>, |
| ) -> RelateResult<'tcx, ty::TypeAndMut<'tcx>> { |
| debug!("{}.mts({:?}, {:?})", relation.tag(), a, b); |
| if a.mutbl != b.mutbl { |
| Err(TypeError::Mutability) |
| } else { |
| let mutbl = a.mutbl; |
| let (variance, info) = match mutbl { |
| hir::Mutability::Not => (ty::Covariant, ty::VarianceDiagInfo::None), |
| hir::Mutability::Mut => { |
| (ty::Invariant, ty::VarianceDiagInfo::Invariant { ty: base_ty, param_index: 0 }) |
| } |
| }; |
| let ty = relation.relate_with_variance(variance, info, a.ty, b.ty)?; |
| Ok(ty::TypeAndMut { ty, mutbl }) |
| } |
| } |
| |
| #[inline] |
| pub fn relate_args_invariantly<'tcx, R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a_arg: GenericArgsRef<'tcx>, |
| b_arg: GenericArgsRef<'tcx>, |
| ) -> RelateResult<'tcx, GenericArgsRef<'tcx>> { |
| relation.tcx().mk_args_from_iter(iter::zip(a_arg, b_arg).map(|(a, b)| { |
| relation.relate_with_variance(ty::Invariant, ty::VarianceDiagInfo::default(), a, b) |
| })) |
| } |
| |
| pub fn relate_args_with_variances<'tcx, R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| ty_def_id: DefId, |
| variances: &[ty::Variance], |
| a_arg: GenericArgsRef<'tcx>, |
| b_arg: GenericArgsRef<'tcx>, |
| fetch_ty_for_diag: bool, |
| ) -> RelateResult<'tcx, GenericArgsRef<'tcx>> { |
| let tcx = relation.tcx(); |
| |
| let mut cached_ty = None; |
| let params = iter::zip(a_arg, b_arg).enumerate().map(|(i, (a, b))| { |
| let variance = variances[i]; |
| let variance_info = if variance == ty::Invariant && fetch_ty_for_diag { |
| let ty = |
| *cached_ty.get_or_insert_with(|| tcx.type_of(ty_def_id).instantiate(tcx, a_arg)); |
| ty::VarianceDiagInfo::Invariant { ty, param_index: i.try_into().unwrap() } |
| } else { |
| ty::VarianceDiagInfo::default() |
| }; |
| relation.relate_with_variance(variance, variance_info, a, b) |
| }); |
| |
| tcx.mk_args_from_iter(params) |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::FnSig<'tcx>, |
| b: ty::FnSig<'tcx>, |
| ) -> RelateResult<'tcx, ty::FnSig<'tcx>> { |
| let tcx = relation.tcx(); |
| |
| if a.c_variadic != b.c_variadic { |
| return Err(TypeError::VariadicMismatch(expected_found( |
| relation, |
| a.c_variadic, |
| b.c_variadic, |
| ))); |
| } |
| let unsafety = relation.relate(a.unsafety, b.unsafety)?; |
| let abi = relation.relate(a.abi, b.abi)?; |
| |
| if a.inputs().len() != b.inputs().len() { |
| return Err(TypeError::ArgCount); |
| } |
| |
| let inputs_and_output = iter::zip(a.inputs(), b.inputs()) |
| .map(|(&a, &b)| ((a, b), false)) |
| .chain(iter::once(((a.output(), b.output()), true))) |
| .map(|((a, b), is_output)| { |
| if is_output { |
| relation.relate(a, b) |
| } else { |
| relation.relate_with_variance( |
| ty::Contravariant, |
| ty::VarianceDiagInfo::default(), |
| a, |
| b, |
| ) |
| } |
| }) |
| .enumerate() |
| .map(|(i, r)| match r { |
| Err(TypeError::Sorts(exp_found) | TypeError::ArgumentSorts(exp_found, _)) => { |
| Err(TypeError::ArgumentSorts(exp_found, i)) |
| } |
| Err(TypeError::Mutability | TypeError::ArgumentMutability(_)) => { |
| Err(TypeError::ArgumentMutability(i)) |
| } |
| r => r, |
| }); |
| Ok(ty::FnSig { |
| inputs_and_output: tcx.mk_type_list_from_iter(inputs_and_output)?, |
| c_variadic: a.c_variadic, |
| unsafety, |
| abi, |
| }) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::BoundConstness { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::BoundConstness, |
| b: ty::BoundConstness, |
| ) -> RelateResult<'tcx, ty::BoundConstness> { |
| if a != b { |
| Err(TypeError::ConstnessMismatch(expected_found(relation, a, b))) |
| } else { |
| Ok(a) |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for hir::Unsafety { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: hir::Unsafety, |
| b: hir::Unsafety, |
| ) -> RelateResult<'tcx, hir::Unsafety> { |
| if a != b { |
| Err(TypeError::UnsafetyMismatch(expected_found(relation, a, b))) |
| } else { |
| Ok(a) |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for abi::Abi { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: abi::Abi, |
| b: abi::Abi, |
| ) -> RelateResult<'tcx, abi::Abi> { |
| if a == b { Ok(a) } else { Err(TypeError::AbiMismatch(expected_found(relation, a, b))) } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::AliasTy<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::AliasTy<'tcx>, |
| b: ty::AliasTy<'tcx>, |
| ) -> RelateResult<'tcx, ty::AliasTy<'tcx>> { |
| if a.def_id != b.def_id { |
| Err(TypeError::ProjectionMismatched(expected_found(relation, a.def_id, b.def_id))) |
| } else { |
| let args = match relation.tcx().def_kind(a.def_id) { |
| DefKind::OpaqueTy => relate_args_with_variances( |
| relation, |
| a.def_id, |
| relation.tcx().variances_of(a.def_id), |
| a.args, |
| b.args, |
| false, // do not fetch `type_of(a_def_id)`, as it will cause a cycle |
| )?, |
| DefKind::AssocTy | DefKind::AssocConst | DefKind::TyAlias => { |
| relate_args_invariantly(relation, a.args, b.args)? |
| } |
| def => bug!("unknown alias DefKind: {def:?}"), |
| }; |
| Ok(ty::AliasTy::new(relation.tcx(), a.def_id, args)) |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::ExistentialProjection<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::ExistentialProjection<'tcx>, |
| b: ty::ExistentialProjection<'tcx>, |
| ) -> RelateResult<'tcx, ty::ExistentialProjection<'tcx>> { |
| if a.def_id != b.def_id { |
| Err(TypeError::ProjectionMismatched(expected_found(relation, a.def_id, b.def_id))) |
| } else { |
| let term = relation.relate_with_variance( |
| ty::Invariant, |
| ty::VarianceDiagInfo::default(), |
| a.term, |
| b.term, |
| )?; |
| let args = relation.relate_with_variance( |
| ty::Invariant, |
| ty::VarianceDiagInfo::default(), |
| a.args, |
| b.args, |
| )?; |
| Ok(ty::ExistentialProjection { def_id: a.def_id, args, term }) |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::TraitRef<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::TraitRef<'tcx>, |
| b: ty::TraitRef<'tcx>, |
| ) -> RelateResult<'tcx, ty::TraitRef<'tcx>> { |
| // Different traits cannot be related. |
| if a.def_id != b.def_id { |
| Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id))) |
| } else { |
| let args = relate_args_invariantly(relation, a.args, b.args)?; |
| Ok(ty::TraitRef::new(relation.tcx(), a.def_id, args)) |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::ExistentialTraitRef<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::ExistentialTraitRef<'tcx>, |
| b: ty::ExistentialTraitRef<'tcx>, |
| ) -> RelateResult<'tcx, ty::ExistentialTraitRef<'tcx>> { |
| // Different traits cannot be related. |
| if a.def_id != b.def_id { |
| Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id))) |
| } else { |
| let args = relate_args_invariantly(relation, a.args, b.args)?; |
| Ok(ty::ExistentialTraitRef { def_id: a.def_id, args }) |
| } |
| } |
| } |
| |
| #[derive(PartialEq, Copy, Debug, Clone, TypeFoldable, TypeVisitable)] |
| struct CoroutineWitness<'tcx>(&'tcx ty::List<Ty<'tcx>>); |
| |
| impl<'tcx> Relate<'tcx> for CoroutineWitness<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: CoroutineWitness<'tcx>, |
| b: CoroutineWitness<'tcx>, |
| ) -> RelateResult<'tcx, CoroutineWitness<'tcx>> { |
| assert_eq!(a.0.len(), b.0.len()); |
| let tcx = relation.tcx(); |
| let types = |
| tcx.mk_type_list_from_iter(iter::zip(a.0, b.0).map(|(a, b)| relation.relate(a, b)))?; |
| Ok(CoroutineWitness(types)) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ImplSubject<'tcx> { |
| #[inline] |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ImplSubject<'tcx>, |
| b: ImplSubject<'tcx>, |
| ) -> RelateResult<'tcx, ImplSubject<'tcx>> { |
| match (a, b) { |
| (ImplSubject::Trait(trait_ref_a), ImplSubject::Trait(trait_ref_b)) => { |
| let trait_ref = ty::TraitRef::relate(relation, trait_ref_a, trait_ref_b)?; |
| Ok(ImplSubject::Trait(trait_ref)) |
| } |
| (ImplSubject::Inherent(ty_a), ImplSubject::Inherent(ty_b)) => { |
| let ty = Ty::relate(relation, ty_a, ty_b)?; |
| Ok(ImplSubject::Inherent(ty)) |
| } |
| (ImplSubject::Trait(_), ImplSubject::Inherent(_)) |
| | (ImplSubject::Inherent(_), ImplSubject::Trait(_)) => { |
| bug!("can not relate TraitRef and Ty"); |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for Ty<'tcx> { |
| #[inline] |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: Ty<'tcx>, |
| b: Ty<'tcx>, |
| ) -> RelateResult<'tcx, Ty<'tcx>> { |
| relation.tys(a, b) |
| } |
| } |
| |
| /// Relates `a` and `b` structurally, calling the relation for all nested values. |
| /// Any semantic equality, e.g. of projections, and inference variables have to be |
| /// handled by the caller. |
| #[instrument(level = "trace", skip(relation), ret)] |
| pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: Ty<'tcx>, |
| b: Ty<'tcx>, |
| ) -> RelateResult<'tcx, Ty<'tcx>> { |
| let tcx = relation.tcx(); |
| match (a.kind(), b.kind()) { |
| (&ty::Infer(_), _) | (_, &ty::Infer(_)) => { |
| // The caller should handle these cases! |
| bug!("var types encountered in structurally_relate_tys") |
| } |
| |
| (ty::Bound(..), _) | (_, ty::Bound(..)) => { |
| bug!("bound types encountered in structurally_relate_tys") |
| } |
| |
| (&ty::Error(guar), _) | (_, &ty::Error(guar)) => Ok(Ty::new_error(tcx, guar)), |
| |
| (&ty::Never, _) |
| | (&ty::Char, _) |
| | (&ty::Bool, _) |
| | (&ty::Int(_), _) |
| | (&ty::Uint(_), _) |
| | (&ty::Float(_), _) |
| | (&ty::Str, _) |
| if a == b => |
| { |
| Ok(a) |
| } |
| |
| (ty::Param(a_p), ty::Param(b_p)) if a_p.index == b_p.index => Ok(a), |
| |
| (ty::Placeholder(p1), ty::Placeholder(p2)) if p1 == p2 => Ok(a), |
| |
| (&ty::Adt(a_def, a_args), &ty::Adt(b_def, b_args)) if a_def == b_def => { |
| let args = relation.relate_item_args(a_def.did(), a_args, b_args)?; |
| Ok(Ty::new_adt(tcx, a_def, args)) |
| } |
| |
| (&ty::Foreign(a_id), &ty::Foreign(b_id)) if a_id == b_id => Ok(Ty::new_foreign(tcx, a_id)), |
| |
| (&ty::Dynamic(a_obj, a_region, a_repr), &ty::Dynamic(b_obj, b_region, b_repr)) |
| if a_repr == b_repr => |
| { |
| let region_bound = relation.with_cause(Cause::ExistentialRegionBound, |relation| { |
| relation.relate(a_region, b_region) |
| })?; |
| Ok(Ty::new_dynamic(tcx, relation.relate(a_obj, b_obj)?, region_bound, a_repr)) |
| } |
| |
| (&ty::Coroutine(a_id, a_args, movability), &ty::Coroutine(b_id, b_args, _)) |
| if a_id == b_id => |
| { |
| // All Coroutine types with the same id represent |
| // the (anonymous) type of the same coroutine expression. So |
| // all of their regions should be equated. |
| let args = relate_args_invariantly(relation, a_args, b_args)?; |
| Ok(Ty::new_coroutine(tcx, a_id, args, movability)) |
| } |
| |
| (&ty::CoroutineWitness(a_id, a_args), &ty::CoroutineWitness(b_id, b_args)) |
| if a_id == b_id => |
| { |
| // All CoroutineWitness types with the same id represent |
| // the (anonymous) type of the same coroutine expression. So |
| // all of their regions should be equated. |
| let args = relate_args_invariantly(relation, a_args, b_args)?; |
| Ok(Ty::new_coroutine_witness(tcx, a_id, args)) |
| } |
| |
| (&ty::Closure(a_id, a_args), &ty::Closure(b_id, b_args)) if a_id == b_id => { |
| // All Closure types with the same id represent |
| // the (anonymous) type of the same closure expression. So |
| // all of their regions should be equated. |
| let args = relate_args_invariantly(relation, a_args, b_args)?; |
| Ok(Ty::new_closure(tcx, a_id, &args)) |
| } |
| |
| (&ty::RawPtr(a_mt), &ty::RawPtr(b_mt)) => { |
| let mt = relate_type_and_mut(relation, a_mt, b_mt, a)?; |
| Ok(Ty::new_ptr(tcx, mt)) |
| } |
| |
| (&ty::Ref(a_r, a_ty, a_mutbl), &ty::Ref(b_r, b_ty, b_mutbl)) => { |
| let r = relation.relate(a_r, b_r)?; |
| let a_mt = ty::TypeAndMut { ty: a_ty, mutbl: a_mutbl }; |
| let b_mt = ty::TypeAndMut { ty: b_ty, mutbl: b_mutbl }; |
| let mt = relate_type_and_mut(relation, a_mt, b_mt, a)?; |
| Ok(Ty::new_ref(tcx, r, mt)) |
| } |
| |
| (&ty::Array(a_t, sz_a), &ty::Array(b_t, sz_b)) => { |
| let t = relation.relate(a_t, b_t)?; |
| match relation.relate(sz_a, sz_b) { |
| Ok(sz) => Ok(Ty::new_array_with_const_len(tcx, t, sz)), |
| Err(err) => { |
| // Check whether the lengths are both concrete/known values, |
| // but are unequal, for better diagnostics. |
| // |
| // It might seem dubious to eagerly evaluate these constants here, |
| // we however cannot end up with errors in `Relate` during both |
| // `type_of` and `predicates_of`. This means that evaluating the |
| // constants should not cause cycle errors here. |
| let sz_a = sz_a.try_eval_target_usize(tcx, relation.param_env()); |
| let sz_b = sz_b.try_eval_target_usize(tcx, relation.param_env()); |
| match (sz_a, sz_b) { |
| (Some(sz_a_val), Some(sz_b_val)) if sz_a_val != sz_b_val => Err( |
| TypeError::FixedArraySize(expected_found(relation, sz_a_val, sz_b_val)), |
| ), |
| _ => Err(err), |
| } |
| } |
| } |
| } |
| |
| (&ty::Slice(a_t), &ty::Slice(b_t)) => { |
| let t = relation.relate(a_t, b_t)?; |
| Ok(Ty::new_slice(tcx, t)) |
| } |
| |
| (&ty::Tuple(as_), &ty::Tuple(bs)) => { |
| if as_.len() == bs.len() { |
| Ok(Ty::new_tup_from_iter( |
| tcx, |
| iter::zip(as_, bs).map(|(a, b)| relation.relate(a, b)), |
| )?) |
| } else if !(as_.is_empty() || bs.is_empty()) { |
| Err(TypeError::TupleSize(expected_found(relation, as_.len(), bs.len()))) |
| } else { |
| Err(TypeError::Sorts(expected_found(relation, a, b))) |
| } |
| } |
| |
| (&ty::FnDef(a_def_id, a_args), &ty::FnDef(b_def_id, b_args)) if a_def_id == b_def_id => { |
| let args = relation.relate_item_args(a_def_id, a_args, b_args)?; |
| Ok(Ty::new_fn_def(tcx, a_def_id, args)) |
| } |
| |
| (&ty::FnPtr(a_fty), &ty::FnPtr(b_fty)) => { |
| let fty = relation.relate(a_fty, b_fty)?; |
| Ok(Ty::new_fn_ptr(tcx, fty)) |
| } |
| |
| // Alias tend to mostly already be handled downstream due to normalization. |
| (&ty::Alias(a_kind, a_data), &ty::Alias(b_kind, b_data)) => { |
| let alias_ty = relation.relate(a_data, b_data)?; |
| assert_eq!(a_kind, b_kind); |
| Ok(Ty::new_alias(tcx, a_kind, alias_ty)) |
| } |
| |
| _ => Err(TypeError::Sorts(expected_found(relation, a, b))), |
| } |
| } |
| |
| /// Relates `a` and `b` structurally, calling the relation for all nested values. |
| /// Any semantic equality, e.g. of unevaluated consts, and inference variables have |
| /// to be handled by the caller. |
| /// |
| /// FIXME: This is not totally structual, which probably should be fixed. |
| /// See the HACKs below. |
| pub fn structurally_relate_consts<'tcx, R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| mut a: ty::Const<'tcx>, |
| mut b: ty::Const<'tcx>, |
| ) -> RelateResult<'tcx, ty::Const<'tcx>> { |
| debug!("{}.structurally_relate_consts(a = {:?}, b = {:?})", relation.tag(), a, b); |
| let tcx = relation.tcx(); |
| |
| if tcx.features().generic_const_exprs { |
| a = tcx.expand_abstract_consts(a); |
| b = tcx.expand_abstract_consts(b); |
| } |
| |
| debug!("{}.structurally_relate_consts(normed_a = {:?}, normed_b = {:?})", relation.tag(), a, b); |
| |
| // Currently, the values that can be unified are primitive types, |
| // and those that derive both `PartialEq` and `Eq`, corresponding |
| // to structural-match types. |
| let is_match = match (a.kind(), b.kind()) { |
| (ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => { |
| // The caller should handle these cases! |
| bug!("var types encountered in structurally_relate_consts: {:?} {:?}", a, b) |
| } |
| |
| (ty::ConstKind::Error(_), _) => return Ok(a), |
| (_, ty::ConstKind::Error(_)) => return Ok(b), |
| |
| (ty::ConstKind::Param(a_p), ty::ConstKind::Param(b_p)) => a_p.index == b_p.index, |
| (ty::ConstKind::Placeholder(p1), ty::ConstKind::Placeholder(p2)) => p1 == p2, |
| (ty::ConstKind::Value(a_val), ty::ConstKind::Value(b_val)) => a_val == b_val, |
| |
| // While this is slightly incorrect, it shouldn't matter for `min_const_generics` |
| // and is the better alternative to waiting until `generic_const_exprs` can |
| // be stabilized. |
| (ty::ConstKind::Unevaluated(au), ty::ConstKind::Unevaluated(bu)) if au.def == bu.def => { |
| assert_eq!(a.ty(), b.ty()); |
| let args = relation.relate_with_variance( |
| ty::Variance::Invariant, |
| ty::VarianceDiagInfo::default(), |
| au.args, |
| bu.args, |
| )?; |
| return Ok(ty::Const::new_unevaluated( |
| tcx, |
| ty::UnevaluatedConst { def: au.def, args }, |
| a.ty(), |
| )); |
| } |
| // Before calling relate on exprs, it is necessary to ensure that the nested consts |
| // have identical types. |
| (ty::ConstKind::Expr(ae), ty::ConstKind::Expr(be)) => { |
| let r = relation; |
| |
| // FIXME(generic_const_exprs): is it possible to relate two consts which are not identical |
| // exprs? Should we care about that? |
| // FIXME(generic_const_exprs): relating the `ty()`s is a little weird since it is supposed to |
| // ICE If they mismatch. Unfortunately `ConstKind::Expr` is a little special and can be thought |
| // of as being generic over the argument types, however this is implicit so these types don't get |
| // related when we relate the args of the item this const arg is for. |
| let expr = match (ae, be) { |
| (Expr::Binop(a_op, al, ar), Expr::Binop(b_op, bl, br)) if a_op == b_op => { |
| r.relate(al.ty(), bl.ty())?; |
| r.relate(ar.ty(), br.ty())?; |
| Expr::Binop(a_op, r.consts(al, bl)?, r.consts(ar, br)?) |
| } |
| (Expr::UnOp(a_op, av), Expr::UnOp(b_op, bv)) if a_op == b_op => { |
| r.relate(av.ty(), bv.ty())?; |
| Expr::UnOp(a_op, r.consts(av, bv)?) |
| } |
| (Expr::Cast(ak, av, at), Expr::Cast(bk, bv, bt)) if ak == bk => { |
| r.relate(av.ty(), bv.ty())?; |
| Expr::Cast(ak, r.consts(av, bv)?, r.tys(at, bt)?) |
| } |
| (Expr::FunctionCall(af, aa), Expr::FunctionCall(bf, ba)) |
| if aa.len() == ba.len() => |
| { |
| r.relate(af.ty(), bf.ty())?; |
| let func = r.consts(af, bf)?; |
| let mut related_args = Vec::with_capacity(aa.len()); |
| for (a_arg, b_arg) in aa.iter().zip(ba.iter()) { |
| related_args.push(r.consts(a_arg, b_arg)?); |
| } |
| let related_args = tcx.mk_const_list(&related_args); |
| Expr::FunctionCall(func, related_args) |
| } |
| _ => return Err(TypeError::ConstMismatch(expected_found(r, a, b))), |
| }; |
| return Ok(ty::Const::new_expr(tcx, expr, a.ty())); |
| } |
| _ => false, |
| }; |
| if is_match { Ok(a) } else { Err(TypeError::ConstMismatch(expected_found(relation, a, b))) } |
| } |
| |
| impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: Self, |
| b: Self, |
| ) -> RelateResult<'tcx, Self> { |
| let tcx = relation.tcx(); |
| |
| // FIXME: this is wasteful, but want to do a perf run to see how slow it is. |
| // We need to perform this deduplication as we sometimes generate duplicate projections |
| // in `a`. |
| let mut a_v: Vec<_> = a.into_iter().collect(); |
| let mut b_v: Vec<_> = b.into_iter().collect(); |
| // `skip_binder` here is okay because `stable_cmp` doesn't look at binders |
| a_v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder())); |
| a_v.dedup(); |
| b_v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder())); |
| b_v.dedup(); |
| if a_v.len() != b_v.len() { |
| return Err(TypeError::ExistentialMismatch(expected_found(relation, a, b))); |
| } |
| |
| let v = iter::zip(a_v, b_v).map(|(ep_a, ep_b)| { |
| use crate::ty::ExistentialPredicate::*; |
| match (ep_a.skip_binder(), ep_b.skip_binder()) { |
| (Trait(a), Trait(b)) => Ok(ep_a |
| .rebind(Trait(relation.relate(ep_a.rebind(a), ep_b.rebind(b))?.skip_binder()))), |
| (Projection(a), Projection(b)) => Ok(ep_a.rebind(Projection( |
| relation.relate(ep_a.rebind(a), ep_b.rebind(b))?.skip_binder(), |
| ))), |
| (AutoTrait(a), AutoTrait(b)) if a == b => Ok(ep_a.rebind(AutoTrait(a))), |
| _ => Err(TypeError::ExistentialMismatch(expected_found(relation, a, b))), |
| } |
| }); |
| tcx.mk_poly_existential_predicates_from_iter(v) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::ClosureArgs<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::ClosureArgs<'tcx>, |
| b: ty::ClosureArgs<'tcx>, |
| ) -> RelateResult<'tcx, ty::ClosureArgs<'tcx>> { |
| let args = relate_args_invariantly(relation, a.args, b.args)?; |
| Ok(ty::ClosureArgs { args }) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::CoroutineArgs<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::CoroutineArgs<'tcx>, |
| b: ty::CoroutineArgs<'tcx>, |
| ) -> RelateResult<'tcx, ty::CoroutineArgs<'tcx>> { |
| let args = relate_args_invariantly(relation, a.args, b.args)?; |
| Ok(ty::CoroutineArgs { args }) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for GenericArgsRef<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: GenericArgsRef<'tcx>, |
| b: GenericArgsRef<'tcx>, |
| ) -> RelateResult<'tcx, GenericArgsRef<'tcx>> { |
| relate_args_invariantly(relation, a, b) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::Region<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::Region<'tcx>, |
| b: ty::Region<'tcx>, |
| ) -> RelateResult<'tcx, ty::Region<'tcx>> { |
| relation.regions(a, b) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::Const<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::Const<'tcx>, |
| b: ty::Const<'tcx>, |
| ) -> RelateResult<'tcx, ty::Const<'tcx>> { |
| relation.consts(a, b) |
| } |
| } |
| |
| impl<'tcx, T: Relate<'tcx>> Relate<'tcx> for ty::Binder<'tcx, T> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::Binder<'tcx, T>, |
| b: ty::Binder<'tcx, T>, |
| ) -> RelateResult<'tcx, ty::Binder<'tcx, T>> { |
| relation.binders(a, b) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for GenericArg<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: GenericArg<'tcx>, |
| b: GenericArg<'tcx>, |
| ) -> RelateResult<'tcx, GenericArg<'tcx>> { |
| match (a.unpack(), b.unpack()) { |
| (GenericArgKind::Lifetime(a_lt), GenericArgKind::Lifetime(b_lt)) => { |
| Ok(relation.relate(a_lt, b_lt)?.into()) |
| } |
| (GenericArgKind::Type(a_ty), GenericArgKind::Type(b_ty)) => { |
| Ok(relation.relate(a_ty, b_ty)?.into()) |
| } |
| (GenericArgKind::Const(a_ct), GenericArgKind::Const(b_ct)) => { |
| Ok(relation.relate(a_ct, b_ct)?.into()) |
| } |
| (GenericArgKind::Lifetime(unpacked), x) => { |
| bug!("impossible case reached: can't relate: {:?} with {:?}", unpacked, x) |
| } |
| (GenericArgKind::Type(unpacked), x) => { |
| bug!("impossible case reached: can't relate: {:?} with {:?}", unpacked, x) |
| } |
| (GenericArgKind::Const(unpacked), x) => { |
| bug!("impossible case reached: can't relate: {:?} with {:?}", unpacked, x) |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::ImplPolarity { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::ImplPolarity, |
| b: ty::ImplPolarity, |
| ) -> RelateResult<'tcx, ty::ImplPolarity> { |
| if a != b { |
| Err(TypeError::PolarityMismatch(expected_found(relation, a, b))) |
| } else { |
| Ok(a) |
| } |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for ty::TraitPredicate<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: ty::TraitPredicate<'tcx>, |
| b: ty::TraitPredicate<'tcx>, |
| ) -> RelateResult<'tcx, ty::TraitPredicate<'tcx>> { |
| Ok(ty::TraitPredicate { |
| trait_ref: relation.relate(a.trait_ref, b.trait_ref)?, |
| polarity: relation.relate(a.polarity, b.polarity)?, |
| }) |
| } |
| } |
| |
| impl<'tcx> Relate<'tcx> for Term<'tcx> { |
| fn relate<R: TypeRelation<'tcx>>( |
| relation: &mut R, |
| a: Self, |
| b: Self, |
| ) -> RelateResult<'tcx, Self> { |
| Ok(match (a.unpack(), b.unpack()) { |
| (TermKind::Ty(a), TermKind::Ty(b)) => relation.relate(a, b)?.into(), |
| (TermKind::Const(a), TermKind::Const(b)) => relation.relate(a, b)?.into(), |
| _ => return Err(TypeError::Mismatch), |
| }) |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Error handling |
| |
| pub fn expected_found<'tcx, R, T>(relation: &mut R, a: T, b: T) -> ExpectedFound<T> |
| where |
| R: TypeRelation<'tcx>, |
| { |
| ExpectedFound::new(relation.a_is_expected(), a, b) |
| } |
