| use crate::traits::error_reporting::TypeErrCtxtExt; |
| use crate::traits::query::evaluate_obligation::InferCtxtExt; |
| use crate::traits::{needs_normalization, BoundVarReplacer, PlaceholderReplacer}; |
| use rustc_data_structures::stack::ensure_sufficient_stack; |
| use rustc_infer::infer::at::At; |
| use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
| use rustc_infer::traits::TraitEngineExt; |
| use rustc_infer::traits::{FulfillmentError, Obligation, TraitEngine}; |
| use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind}; |
| use rustc_middle::traits::Reveal; |
| use rustc_middle::ty::{self, AliasTy, Ty, TyCtxt, UniverseIndex}; |
| use rustc_middle::ty::{FallibleTypeFolder, TypeSuperFoldable}; |
| use rustc_middle::ty::{TypeFoldable, TypeVisitableExt}; |
| |
| use super::FulfillmentCtxt; |
| |
| /// Deeply normalize all aliases in `value`. This does not handle inference and expects |
| /// its input to be already fully resolved. |
| pub(crate) fn deeply_normalize<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>( |
| at: At<'_, 'tcx>, |
| value: T, |
| ) -> Result<T, Vec<FulfillmentError<'tcx>>> { |
| assert!(!value.has_escaping_bound_vars()); |
| deeply_normalize_with_skipped_universes(at, value, vec![]) |
| } |
| |
| /// Deeply normalize all aliases in `value`. This does not handle inference and expects |
| /// its input to be already fully resolved. |
| /// |
| /// Additionally takes a list of universes which represents the binders which have been |
| /// entered before passing `value` to the function. This is currently needed for |
| /// `normalize_erasing_regions`, which skips binders as it walks through a type. |
| pub(crate) fn deeply_normalize_with_skipped_universes<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>( |
| at: At<'_, 'tcx>, |
| value: T, |
| universes: Vec<Option<UniverseIndex>>, |
| ) -> Result<T, Vec<FulfillmentError<'tcx>>> { |
| let fulfill_cx = FulfillmentCtxt::new(at.infcx); |
| let mut folder = NormalizationFolder { at, fulfill_cx, depth: 0, universes }; |
| |
| value.try_fold_with(&mut folder) |
| } |
| |
| struct NormalizationFolder<'me, 'tcx> { |
| at: At<'me, 'tcx>, |
| fulfill_cx: FulfillmentCtxt<'tcx>, |
| depth: usize, |
| universes: Vec<Option<UniverseIndex>>, |
| } |
| |
| impl<'tcx> NormalizationFolder<'_, 'tcx> { |
| fn normalize_alias_ty( |
| &mut self, |
| alias: AliasTy<'tcx>, |
| ) -> Result<Ty<'tcx>, Vec<FulfillmentError<'tcx>>> { |
| let infcx = self.at.infcx; |
| let tcx = infcx.tcx; |
| let recursion_limit = tcx.recursion_limit(); |
| if !recursion_limit.value_within_limit(self.depth) { |
| self.at.infcx.err_ctxt().report_overflow_error( |
| &alias.to_ty(tcx), |
| self.at.cause.span, |
| true, |
| |_| {}, |
| ); |
| } |
| |
| self.depth += 1; |
| |
| let new_infer_ty = infcx.next_ty_var(TypeVariableOrigin { |
| kind: TypeVariableOriginKind::NormalizeProjectionType, |
| span: self.at.cause.span, |
| }); |
| let obligation = Obligation::new( |
| tcx, |
| self.at.cause.clone(), |
| self.at.param_env, |
| ty::ProjectionPredicate { projection_ty: alias, term: new_infer_ty.into() }, |
| ); |
| |
| // Do not emit an error if normalization is known to fail but instead |
| // keep the projection unnormalized. This is the case for projections |
| // with a `T: Trait` where-clause and opaque types outside of the defining |
| // scope. |
| let result = if infcx.predicate_may_hold(&obligation) { |
| self.fulfill_cx.register_predicate_obligation(infcx, obligation); |
| let errors = self.fulfill_cx.select_all_or_error(infcx); |
| if !errors.is_empty() { |
| return Err(errors); |
| } |
| let ty = infcx.resolve_vars_if_possible(new_infer_ty); |
| ty.try_fold_with(self)? |
| } else { |
| alias.to_ty(tcx).try_super_fold_with(self)? |
| }; |
| |
| self.depth -= 1; |
| Ok(result) |
| } |
| |
| fn normalize_unevaluated_const( |
| &mut self, |
| ty: Ty<'tcx>, |
| uv: ty::UnevaluatedConst<'tcx>, |
| ) -> Result<ty::Const<'tcx>, Vec<FulfillmentError<'tcx>>> { |
| let infcx = self.at.infcx; |
| let tcx = infcx.tcx; |
| let recursion_limit = tcx.recursion_limit(); |
| if !recursion_limit.value_within_limit(self.depth) { |
| self.at.infcx.err_ctxt().report_overflow_error( |
| &ty::Const::new_unevaluated(tcx, uv, ty), |
| self.at.cause.span, |
| true, |
| |_| {}, |
| ); |
| } |
| |
| self.depth += 1; |
| |
| let new_infer_ct = infcx.next_const_var( |
| ty, |
| ConstVariableOrigin { |
| kind: ConstVariableOriginKind::MiscVariable, |
| span: self.at.cause.span, |
| }, |
| ); |
| let obligation = Obligation::new( |
| tcx, |
| self.at.cause.clone(), |
| self.at.param_env, |
| ty::ProjectionPredicate { |
| projection_ty: AliasTy::new(tcx, uv.def, uv.args), |
| term: new_infer_ct.into(), |
| }, |
| ); |
| |
| let result = if infcx.predicate_may_hold(&obligation) { |
| self.fulfill_cx.register_predicate_obligation(infcx, obligation); |
| let errors = self.fulfill_cx.select_all_or_error(infcx); |
| if !errors.is_empty() { |
| return Err(errors); |
| } |
| let ct = infcx.resolve_vars_if_possible(new_infer_ct); |
| ct.try_fold_with(self)? |
| } else { |
| ty::Const::new_unevaluated(tcx, uv, ty).try_super_fold_with(self)? |
| }; |
| |
| self.depth -= 1; |
| Ok(result) |
| } |
| } |
| |
| impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for NormalizationFolder<'_, 'tcx> { |
| type Error = Vec<FulfillmentError<'tcx>>; |
| |
| fn interner(&self) -> TyCtxt<'tcx> { |
| self.at.infcx.tcx |
| } |
| |
| fn try_fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>( |
| &mut self, |
| t: ty::Binder<'tcx, T>, |
| ) -> Result<ty::Binder<'tcx, T>, Self::Error> { |
| self.universes.push(None); |
| let t = t.try_super_fold_with(self)?; |
| self.universes.pop(); |
| Ok(t) |
| } |
| |
| fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result<Ty<'tcx>, Self::Error> { |
| let reveal = self.at.param_env.reveal(); |
| let infcx = self.at.infcx; |
| debug_assert_eq!(ty, infcx.shallow_resolve(ty)); |
| if !needs_normalization(&ty, reveal) { |
| return Ok(ty); |
| } |
| |
| // We don't normalize opaque types unless we have |
| // `Reveal::All`, even if we're in the defining scope. |
| let data = match *ty.kind() { |
| ty::Alias(kind, alias_ty) if kind != ty::Opaque || reveal == Reveal::All => alias_ty, |
| _ => return ty.try_super_fold_with(self), |
| }; |
| |
| if data.has_escaping_bound_vars() { |
| let (data, mapped_regions, mapped_types, mapped_consts) = |
| BoundVarReplacer::replace_bound_vars(infcx, &mut self.universes, data); |
| let result = ensure_sufficient_stack(|| self.normalize_alias_ty(data))?; |
| Ok(PlaceholderReplacer::replace_placeholders( |
| infcx, |
| mapped_regions, |
| mapped_types, |
| mapped_consts, |
| &self.universes, |
| result, |
| )) |
| } else { |
| ensure_sufficient_stack(|| self.normalize_alias_ty(data)) |
| } |
| } |
| |
| fn try_fold_const(&mut self, ct: ty::Const<'tcx>) -> Result<ty::Const<'tcx>, Self::Error> { |
| let reveal = self.at.param_env.reveal(); |
| let infcx = self.at.infcx; |
| debug_assert_eq!(ct, infcx.shallow_resolve(ct)); |
| if !needs_normalization(&ct, reveal) { |
| return Ok(ct); |
| } |
| |
| let uv = match ct.kind() { |
| ty::ConstKind::Unevaluated(ct) => ct, |
| _ => return ct.try_super_fold_with(self), |
| }; |
| |
| if uv.has_escaping_bound_vars() { |
| let (uv, mapped_regions, mapped_types, mapped_consts) = |
| BoundVarReplacer::replace_bound_vars(infcx, &mut self.universes, uv); |
| let result = ensure_sufficient_stack(|| self.normalize_unevaluated_const(ct.ty(), uv))?; |
| Ok(PlaceholderReplacer::replace_placeholders( |
| infcx, |
| mapped_regions, |
| mapped_types, |
| mapped_consts, |
| &self.universes, |
| result, |
| )) |
| } else { |
| ensure_sufficient_stack(|| self.normalize_unevaluated_const(ct.ty(), uv)) |
| } |
| } |
| } |