diff options
Diffstat (limited to 'compiler/rustc_borrowck/src/region_infer/opaque_types.rs')
| -rw-r--r-- | compiler/rustc_borrowck/src/region_infer/opaque_types.rs | 374 |
1 files changed, 64 insertions, 310 deletions
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs index 9d088642f..465f353aa 100644 --- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs +++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs @@ -2,22 +2,18 @@ use rustc_data_structures::fx::FxHashMap; use rustc_data_structures::vec_map::VecMap; use rustc_hir::def_id::LocalDefId; use rustc_hir::OpaqueTyOrigin; -use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic; use rustc_infer::infer::TyCtxtInferExt as _; use rustc_infer::infer::{DefiningAnchor, InferCtxt}; use rustc_infer::traits::{Obligation, ObligationCause, TraitEngine}; -use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable}; -use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts}; +use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts}; use rustc_middle::ty::visit::TypeVisitable; use rustc_middle::ty::{ self, OpaqueHiddenType, OpaqueTypeKey, ToPredicate, Ty, TyCtxt, TypeFoldable, }; use rustc_span::Span; -use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _; +use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _; use rustc_trait_selection::traits::TraitEngineExt as _; -use crate::session_diagnostics::ConstNotUsedTraitAlias; - use super::RegionInferenceContext; impl<'tcx> RegionInferenceContext<'tcx> { @@ -63,7 +59,7 @@ impl<'tcx> RegionInferenceContext<'tcx> { #[instrument(level = "debug", skip(self, infcx), ret)] pub(crate) fn infer_opaque_types( &self, - infcx: &InferCtxt<'_, 'tcx>, + infcx: &InferCtxt<'tcx>, opaque_ty_decls: VecMap<OpaqueTypeKey<'tcx>, (OpaqueHiddenType<'tcx>, OpaqueTyOrigin)>, ) -> VecMap<LocalDefId, OpaqueHiddenType<'tcx>> { let mut result: VecMap<LocalDefId, OpaqueHiddenType<'tcx>> = VecMap::new(); @@ -194,7 +190,7 @@ pub trait InferCtxtExt<'tcx> { ) -> Ty<'tcx>; } -impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { +impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> { /// Given the fully resolved, instantiated type for an opaque /// type, i.e., the value of an inference variable like C1 or C2 /// (*), computes the "definition type" for an opaque type @@ -229,31 +225,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { return self.tcx.ty_error(); } - let OpaqueTypeKey { def_id, substs } = opaque_type_key; - - // Use substs to build up a reverse map from regions to their - // identity mappings. This is necessary because of `impl - // Trait` lifetimes are computed by replacing existing - // lifetimes with 'static and remapping only those used in the - // `impl Trait` return type, resulting in the parameters - // shifting. - let id_substs = InternalSubsts::identity_for_item(self.tcx, def_id.to_def_id()); - debug!(?id_substs); - let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> = - substs.iter().enumerate().map(|(index, subst)| (subst, id_substs[index])).collect(); - debug!("map = {:#?}", map); - - // Convert the type from the function into a type valid outside - // the function, by replacing invalid regions with 'static, - // after producing an error for each of them. - let definition_ty = instantiated_ty.ty.fold_with(&mut ReverseMapper::new( - self.tcx, - opaque_type_key, - map, - instantiated_ty.ty, - instantiated_ty.span, - )); - debug!(?definition_ty); + let definition_ty = instantiated_ty + .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false, origin) + .ty; if !check_opaque_type_parameter_valid( self.tcx, @@ -266,72 +240,70 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { // Only check this for TAIT. RPIT already supports `src/test/ui/impl-trait/nested-return-type2.rs` // on stable and we'd break that. - if let OpaqueTyOrigin::TyAlias = origin { - // This logic duplicates most of `check_opaque_meets_bounds`. - // FIXME(oli-obk): Also do region checks here and then consider removing `check_opaque_meets_bounds` entirely. - let param_env = self.tcx.param_env(def_id); - let body_id = self.tcx.local_def_id_to_hir_id(def_id); - // HACK This bubble is required for this tests to pass: - // type-alias-impl-trait/issue-67844-nested-opaque.rs - self.tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).enter( - move |infcx| { - // Require the hidden type to be well-formed with only the generics of the opaque type. - // Defining use functions may have more bounds than the opaque type, which is ok, as long as the - // hidden type is well formed even without those bounds. - let predicate = - ty::Binder::dummy(ty::PredicateKind::WellFormed(definition_ty.into())) - .to_predicate(infcx.tcx); - let mut fulfillment_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx); + let OpaqueTyOrigin::TyAlias = origin else { + return definition_ty; + }; + let def_id = opaque_type_key.def_id; + // This logic duplicates most of `check_opaque_meets_bounds`. + // FIXME(oli-obk): Also do region checks here and then consider removing `check_opaque_meets_bounds` entirely. + let param_env = self.tcx.param_env(def_id); + let body_id = self.tcx.local_def_id_to_hir_id(def_id); + // HACK This bubble is required for this tests to pass: + // type-alias-impl-trait/issue-67844-nested-opaque.rs + let infcx = + self.tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).build(); + // Require the hidden type to be well-formed with only the generics of the opaque type. + // Defining use functions may have more bounds than the opaque type, which is ok, as long as the + // hidden type is well formed even without those bounds. + let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(definition_ty.into())) + .to_predicate(infcx.tcx); + let mut fulfillment_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx); - // Require that the hidden type actually fulfills all the bounds of the opaque type, even without - // the bounds that the function supplies. - match infcx.register_hidden_type( - OpaqueTypeKey { def_id, substs: id_substs }, - ObligationCause::misc(instantiated_ty.span, body_id), - param_env, + let id_substs = InternalSubsts::identity_for_item(self.tcx, def_id.to_def_id()); + + // Require that the hidden type actually fulfills all the bounds of the opaque type, even without + // the bounds that the function supplies. + let opaque_ty = self.tcx.mk_opaque(def_id.to_def_id(), id_substs); + match infcx + .at(&ObligationCause::misc(instantiated_ty.span, body_id), param_env) + .eq(opaque_ty, definition_ty) + { + Ok(infer_ok) => { + for obligation in infer_ok.obligations { + fulfillment_cx.register_predicate_obligation(&infcx, obligation); + } + } + Err(err) => { + infcx + .err_ctxt() + .report_mismatched_types( + &ObligationCause::misc(instantiated_ty.span, body_id), + opaque_ty, definition_ty, - origin, - ) { - Ok(infer_ok) => { - for obligation in infer_ok.obligations { - fulfillment_cx.register_predicate_obligation(&infcx, obligation); - } - } - Err(err) => { - infcx - .report_mismatched_types( - &ObligationCause::misc(instantiated_ty.span, body_id), - self.tcx.mk_opaque(def_id.to_def_id(), id_substs), - definition_ty, - err, - ) - .emit(); - } - } + err, + ) + .emit(); + } + } - fulfillment_cx.register_predicate_obligation( - &infcx, - Obligation::misc(instantiated_ty.span, body_id, param_env, predicate), - ); + fulfillment_cx.register_predicate_obligation( + &infcx, + Obligation::misc(instantiated_ty.span, body_id, param_env, predicate), + ); - // Check that all obligations are satisfied by the implementation's - // version. - let errors = fulfillment_cx.select_all_or_error(&infcx); + // Check that all obligations are satisfied by the implementation's + // version. + let errors = fulfillment_cx.select_all_or_error(&infcx); - // This is still required for many(half of the tests in ui/type-alias-impl-trait) - // tests to pass - let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types(); + // This is still required for many(half of the tests in ui/type-alias-impl-trait) + // tests to pass + let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types(); - if errors.is_empty() { - definition_ty - } else { - infcx.report_fulfillment_errors(&errors, None, false); - self.tcx.ty_error() - } - }, - ) - } else { + if errors.is_empty() { definition_ty + } else { + infcx.err_ctxt().report_fulfillment_errors(&errors, None, false); + self.tcx.ty_error() } } } @@ -427,221 +399,3 @@ fn check_opaque_type_parameter_valid( } true } - -struct ReverseMapper<'tcx> { - tcx: TyCtxt<'tcx>, - - key: ty::OpaqueTypeKey<'tcx>, - map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>, - do_not_error: bool, - - /// initially `Some`, set to `None` once error has been reported - hidden_ty: Option<Ty<'tcx>>, - - /// Span of function being checked. - span: Span, -} - -impl<'tcx> ReverseMapper<'tcx> { - fn new( - tcx: TyCtxt<'tcx>, - key: ty::OpaqueTypeKey<'tcx>, - map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>, - hidden_ty: Ty<'tcx>, - span: Span, - ) -> Self { - Self { tcx, key, map, do_not_error: false, hidden_ty: Some(hidden_ty), span } - } - - fn fold_kind_no_missing_regions_error(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> { - assert!(!self.do_not_error); - self.do_not_error = true; - let kind = kind.fold_with(self); - self.do_not_error = false; - kind - } - - fn fold_kind_normally(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> { - assert!(!self.do_not_error); - kind.fold_with(self) - } -} - -impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> { - fn tcx(&self) -> TyCtxt<'tcx> { - self.tcx - } - - #[instrument(skip(self), level = "debug")] - fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { - match *r { - // Ignore bound regions and `'static` regions that appear in the - // type, we only need to remap regions that reference lifetimes - // from the function declaration. - // This would ignore `'r` in a type like `for<'r> fn(&'r u32)`. - ty::ReLateBound(..) | ty::ReStatic => return r, - - // If regions have been erased (by writeback), don't try to unerase - // them. - ty::ReErased => return r, - - // The regions that we expect from borrow checking. - ty::ReEarlyBound(_) | ty::ReFree(_) => {} - - ty::RePlaceholder(_) | ty::ReVar(_) => { - // All of the regions in the type should either have been - // erased by writeback, or mapped back to named regions by - // borrow checking. - bug!("unexpected region kind in opaque type: {:?}", r); - } - } - - let generics = self.tcx().generics_of(self.key.def_id); - match self.map.get(&r.into()).map(|k| k.unpack()) { - Some(GenericArgKind::Lifetime(r1)) => r1, - Some(u) => panic!("region mapped to unexpected kind: {:?}", u), - None if self.do_not_error => self.tcx.lifetimes.re_static, - None if generics.parent.is_some() => { - if let Some(hidden_ty) = self.hidden_ty.take() { - unexpected_hidden_region_diagnostic( - self.tcx, - self.tcx.def_span(self.key.def_id), - hidden_ty, - r, - self.key, - ) - .emit(); - } - self.tcx.lifetimes.re_static - } - None => { - self.tcx - .sess - .struct_span_err(self.span, "non-defining opaque type use in defining scope") - .span_label( - self.span, - format!( - "lifetime `{}` is part of concrete type but not used in \ - parameter list of the `impl Trait` type alias", - r - ), - ) - .emit(); - - self.tcx().lifetimes.re_static - } - } - } - - fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { - match *ty.kind() { - ty::Closure(def_id, substs) => { - // I am a horrible monster and I pray for death. When - // we encounter a closure here, it is always a closure - // from within the function that we are currently - // type-checking -- one that is now being encapsulated - // in an opaque type. Ideally, we would - // go through the types/lifetimes that it references - // and treat them just like we would any other type, - // which means we would error out if we find any - // reference to a type/region that is not in the - // "reverse map". - // - // **However,** in the case of closures, there is a - // somewhat subtle (read: hacky) consideration. The - // problem is that our closure types currently include - // all the lifetime parameters declared on the - // enclosing function, even if they are unused by the - // closure itself. We can't readily filter them out, - // so here we replace those values with `'empty`. This - // can't really make a difference to the rest of the - // compiler; those regions are ignored for the - // outlives relation, and hence don't affect trait - // selection or auto traits, and they are erased - // during codegen. - - let generics = self.tcx.generics_of(def_id); - let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| { - if index < generics.parent_count { - // Accommodate missing regions in the parent kinds... - self.fold_kind_no_missing_regions_error(kind) - } else { - // ...but not elsewhere. - self.fold_kind_normally(kind) - } - })); - - self.tcx.mk_closure(def_id, substs) - } - - ty::Generator(def_id, substs, movability) => { - let generics = self.tcx.generics_of(def_id); - let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| { - if index < generics.parent_count { - // Accommodate missing regions in the parent kinds... - self.fold_kind_no_missing_regions_error(kind) - } else { - // ...but not elsewhere. - self.fold_kind_normally(kind) - } - })); - - self.tcx.mk_generator(def_id, substs, movability) - } - - ty::Param(param) => { - // Look it up in the substitution list. - match self.map.get(&ty.into()).map(|k| k.unpack()) { - // Found it in the substitution list; replace with the parameter from the - // opaque type. - Some(GenericArgKind::Type(t1)) => t1, - Some(u) => panic!("type mapped to unexpected kind: {:?}", u), - None => { - debug!(?param, ?self.map); - self.tcx - .sess - .struct_span_err( - self.span, - &format!( - "type parameter `{}` is part of concrete type but not \ - used in parameter list for the `impl Trait` type alias", - ty - ), - ) - .emit(); - - self.tcx().ty_error() - } - } - } - - _ => ty.super_fold_with(self), - } - } - - fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> { - trace!("checking const {:?}", ct); - // Find a const parameter - match ct.kind() { - ty::ConstKind::Param(..) => { - // Look it up in the substitution list. - match self.map.get(&ct.into()).map(|k| k.unpack()) { - // Found it in the substitution list, replace with the parameter from the - // opaque type. - Some(GenericArgKind::Const(c1)) => c1, - Some(u) => panic!("const mapped to unexpected kind: {:?}", u), - None => { - self.tcx.sess.emit_err(ConstNotUsedTraitAlias { - ct: ct.to_string(), - span: self.span, - }); - - self.tcx().const_error(ct.ty()) - } - } - } - - _ => ct, - } - } -} |