Move code from rustc_trait_selection/opaque_types to better places
This commit is contained in:
Jack Huey
parent
2471431017
commit
31e1a777e7
@ -1,11 +1,20 @@
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use rustc_data_structures::fx::FxHashMap;
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use rustc_data_structures::vec_map::VecMap;
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use rustc_hir::def_id::DefId;
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use rustc_hir::OpaqueTyOrigin;
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use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic;
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use rustc_infer::infer::InferCtxt;
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use rustc_infer::infer::TyCtxtInferExt as _;
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use rustc_infer::traits::{Obligation, ObligationCause, TraitEngine};
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use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
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use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts};
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use rustc_middle::ty::visit::TypeVisitable;
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use rustc_middle::ty::{
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self, OpaqueHiddenType, OpaqueTypeKey, TyCtxt, TypeFoldable, TypeVisitable,
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self, OpaqueHiddenType, OpaqueTypeKey, ToPredicate, Ty, TyCtxt, TypeFoldable,
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};
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use rustc_trait_selection::opaque_types::InferCtxtExt;
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use rustc_span::Span;
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use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
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use rustc_trait_selection::traits::TraitEngineExt as _;
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use super::RegionInferenceContext;
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@ -173,3 +182,474 @@ pub(crate) fn name_regions<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T
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})
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}
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}
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pub trait InferCtxtExt<'tcx> {
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fn infer_opaque_definition_from_instantiation(
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&self,
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opaque_type_key: OpaqueTypeKey<'tcx>,
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instantiated_ty: OpaqueHiddenType<'tcx>,
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origin: OpaqueTyOrigin,
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) -> Ty<'tcx>;
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}
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impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
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/// Given the fully resolved, instantiated type for an opaque
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/// type, i.e., the value of an inference variable like C1 or C2
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/// (*), computes the "definition type" for an opaque type
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/// definition -- that is, the inferred value of `Foo1<'x>` or
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/// `Foo2<'x>` that we would conceptually use in its definition:
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/// ```ignore (illustrative)
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/// type Foo1<'x> = impl Bar<'x> = AAA; // <-- this type AAA
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/// type Foo2<'x> = impl Bar<'x> = BBB; // <-- or this type BBB
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/// fn foo<'a, 'b>(..) -> (Foo1<'a>, Foo2<'b>) { .. }
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/// ```
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/// Note that these values are defined in terms of a distinct set of
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/// generic parameters (`'x` instead of `'a`) from C1 or C2. The main
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/// purpose of this function is to do that translation.
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///
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/// (*) C1 and C2 were introduced in the comments on
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/// `register_member_constraints`. Read that comment for more context.
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///
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/// # Parameters
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///
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/// - `def_id`, the `impl Trait` type
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/// - `substs`, the substs used to instantiate this opaque type
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/// - `instantiated_ty`, the inferred type C1 -- fully resolved, lifted version of
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/// `opaque_defn.concrete_ty`
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#[instrument(level = "debug", skip(self))]
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fn infer_opaque_definition_from_instantiation(
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&self,
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opaque_type_key: OpaqueTypeKey<'tcx>,
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instantiated_ty: OpaqueHiddenType<'tcx>,
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origin: OpaqueTyOrigin,
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) -> Ty<'tcx> {
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if self.is_tainted_by_errors() {
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return self.tcx.ty_error();
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}
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let OpaqueTypeKey { def_id, substs } = opaque_type_key;
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// Use substs to build up a reverse map from regions to their
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// identity mappings. This is necessary because of `impl
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// Trait` lifetimes are computed by replacing existing
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// lifetimes with 'static and remapping only those used in the
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// `impl Trait` return type, resulting in the parameters
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// shifting.
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let id_substs = InternalSubsts::identity_for_item(self.tcx, def_id);
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debug!(?id_substs);
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let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> =
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substs.iter().enumerate().map(|(index, subst)| (subst, id_substs[index])).collect();
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debug!("map = {:#?}", map);
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// Convert the type from the function into a type valid outside
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// the function, by replacing invalid regions with 'static,
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// after producing an error for each of them.
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let definition_ty = instantiated_ty.ty.fold_with(&mut ReverseMapper::new(
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self.tcx,
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def_id,
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map,
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instantiated_ty.ty,
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instantiated_ty.span,
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));
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debug!(?definition_ty);
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if !check_opaque_type_parameter_valid(
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self.tcx,
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opaque_type_key,
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origin,
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instantiated_ty.span,
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) {
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return self.tcx.ty_error();
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}
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// Only check this for TAIT. RPIT already supports `src/test/ui/impl-trait/nested-return-type2.rs`
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// on stable and we'd break that.
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if let OpaqueTyOrigin::TyAlias = origin {
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// This logic duplicates most of `check_opaque_meets_bounds`.
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// FIXME(oli-obk): Also do region checks here and then consider removing `check_opaque_meets_bounds` entirely.
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let param_env = self.tcx.param_env(def_id);
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let body_id = self.tcx.local_def_id_to_hir_id(def_id.as_local().unwrap());
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self.tcx.infer_ctxt().enter(move |infcx| {
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// Require the hidden type to be well-formed with only the generics of the opaque type.
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// Defining use functions may have more bounds than the opaque type, which is ok, as long as the
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// hidden type is well formed even without those bounds.
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let predicate =
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ty::Binder::dummy(ty::PredicateKind::WellFormed(definition_ty.into()))
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.to_predicate(infcx.tcx);
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let mut fulfillment_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
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// Require that the hidden type actually fulfills all the bounds of the opaque type, even without
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// the bounds that the function supplies.
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match infcx.register_hidden_type(
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OpaqueTypeKey { def_id, substs: id_substs },
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ObligationCause::misc(instantiated_ty.span, body_id),
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param_env,
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definition_ty,
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origin,
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) {
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Ok(infer_ok) => {
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for obligation in infer_ok.obligations {
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fulfillment_cx.register_predicate_obligation(&infcx, obligation);
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}
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}
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Err(err) => {
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infcx
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.report_mismatched_types(
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&ObligationCause::misc(instantiated_ty.span, body_id),
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self.tcx.mk_opaque(def_id, id_substs),
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definition_ty,
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err,
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)
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.emit();
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}
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}
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fulfillment_cx.register_predicate_obligation(
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&infcx,
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Obligation::misc(instantiated_ty.span, body_id, param_env, predicate),
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);
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// Check that all obligations are satisfied by the implementation's
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// version.
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let errors = fulfillment_cx.select_all_or_error(&infcx);
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let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
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if errors.is_empty() {
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definition_ty
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} else {
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infcx.report_fulfillment_errors(&errors, None, false);
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self.tcx.ty_error()
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}
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})
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} else {
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definition_ty
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}
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}
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}
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fn check_opaque_type_parameter_valid(
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tcx: TyCtxt<'_>,
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opaque_type_key: OpaqueTypeKey<'_>,
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origin: OpaqueTyOrigin,
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span: Span,
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) -> bool {
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match origin {
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// No need to check return position impl trait (RPIT)
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// because for type and const parameters they are correct
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// by construction: we convert
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//
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// fn foo<P0..Pn>() -> impl Trait
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//
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// into
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//
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// type Foo<P0...Pn>
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// fn foo<P0..Pn>() -> Foo<P0...Pn>.
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//
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// For lifetime parameters we convert
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//
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// fn foo<'l0..'ln>() -> impl Trait<'l0..'lm>
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//
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// into
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//
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// type foo::<'p0..'pn>::Foo<'q0..'qm>
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// fn foo<l0..'ln>() -> foo::<'static..'static>::Foo<'l0..'lm>.
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//
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// which would error here on all of the `'static` args.
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OpaqueTyOrigin::FnReturn(..) | OpaqueTyOrigin::AsyncFn(..) => return true,
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// Check these
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OpaqueTyOrigin::TyAlias => {}
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}
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let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
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let mut seen_params: FxHashMap<_, Vec<_>> = FxHashMap::default();
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for (i, arg) in opaque_type_key.substs.iter().enumerate() {
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let arg_is_param = match arg.unpack() {
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GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
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GenericArgKind::Lifetime(lt) if lt.is_static() => {
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tcx.sess
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.struct_span_err(span, "non-defining opaque type use in defining scope")
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.span_label(
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tcx.def_span(opaque_generics.param_at(i, tcx).def_id),
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"cannot use static lifetime; use a bound lifetime \
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instead or remove the lifetime parameter from the \
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opaque type",
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)
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.emit();
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return false;
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}
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GenericArgKind::Lifetime(lt) => {
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matches!(*lt, ty::ReEarlyBound(_) | ty::ReFree(_))
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}
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GenericArgKind::Const(ct) => matches!(ct.kind(), ty::ConstKind::Param(_)),
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};
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if arg_is_param {
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seen_params.entry(arg).or_default().push(i);
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} else {
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// Prevent `fn foo() -> Foo<u32>` from being defining.
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let opaque_param = opaque_generics.param_at(i, tcx);
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tcx.sess
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.struct_span_err(span, "non-defining opaque type use in defining scope")
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.span_note(
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tcx.def_span(opaque_param.def_id),
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&format!(
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"used non-generic {} `{}` for generic parameter",
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opaque_param.kind.descr(),
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arg,
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),
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)
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.emit();
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return false;
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}
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}
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for (_, indices) in seen_params {
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if indices.len() > 1 {
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let descr = opaque_generics.param_at(indices[0], tcx).kind.descr();
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let spans: Vec<_> = indices
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.into_iter()
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.map(|i| tcx.def_span(opaque_generics.param_at(i, tcx).def_id))
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.collect();
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tcx.sess
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.struct_span_err(span, "non-defining opaque type use in defining scope")
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.span_note(spans, &format!("{} used multiple times", descr))
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.emit();
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return false;
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}
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}
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true
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}
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struct ReverseMapper<'tcx> {
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tcx: TyCtxt<'tcx>,
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opaque_type_def_id: DefId,
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map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
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map_missing_regions_to_empty: bool,
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/// initially `Some`, set to `None` once error has been reported
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hidden_ty: Option<Ty<'tcx>>,
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/// Span of function being checked.
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span: Span,
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}
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impl<'tcx> ReverseMapper<'tcx> {
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fn new(
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tcx: TyCtxt<'tcx>,
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opaque_type_def_id: DefId,
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map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
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hidden_ty: Ty<'tcx>,
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span: Span,
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) -> Self {
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Self {
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tcx,
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opaque_type_def_id,
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map,
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map_missing_regions_to_empty: false,
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hidden_ty: Some(hidden_ty),
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span,
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}
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}
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fn fold_kind_mapping_missing_regions_to_empty(
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&mut self,
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kind: GenericArg<'tcx>,
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) -> GenericArg<'tcx> {
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assert!(!self.map_missing_regions_to_empty);
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self.map_missing_regions_to_empty = true;
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let kind = kind.fold_with(self);
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self.map_missing_regions_to_empty = false;
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kind
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}
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fn fold_kind_normally(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
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assert!(!self.map_missing_regions_to_empty);
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kind.fold_with(self)
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}
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}
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impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
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fn tcx(&self) -> TyCtxt<'tcx> {
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self.tcx
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}
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#[instrument(skip(self), level = "debug")]
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fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
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match *r {
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// Ignore bound regions and `'static` regions that appear in the
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// type, we only need to remap regions that reference lifetimes
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// from the function declaration.
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// This would ignore `'r` in a type like `for<'r> fn(&'r u32)`.
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ty::ReLateBound(..) | ty::ReStatic => return r,
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// If regions have been erased (by writeback), don't try to unerase
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// them.
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ty::ReErased => return r,
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// The regions that we expect from borrow checking.
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ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReEmpty(ty::UniverseIndex::ROOT) => {}
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ty::ReEmpty(_) | ty::RePlaceholder(_) | ty::ReVar(_) => {
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// All of the regions in the type should either have been
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// erased by writeback, or mapped back to named regions by
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// borrow checking.
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bug!("unexpected region kind in opaque type: {:?}", r);
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}
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}
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let generics = self.tcx().generics_of(self.opaque_type_def_id);
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match self.map.get(&r.into()).map(|k| k.unpack()) {
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Some(GenericArgKind::Lifetime(r1)) => r1,
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Some(u) => panic!("region mapped to unexpected kind: {:?}", u),
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None if self.map_missing_regions_to_empty => self.tcx.lifetimes.re_root_empty,
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None if generics.parent.is_some() => {
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if let Some(hidden_ty) = self.hidden_ty.take() {
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unexpected_hidden_region_diagnostic(
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self.tcx,
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self.tcx.def_span(self.opaque_type_def_id),
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hidden_ty,
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r,
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)
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.emit();
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}
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self.tcx.lifetimes.re_root_empty
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}
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None => {
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self.tcx
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.sess
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.struct_span_err(self.span, "non-defining opaque type use in defining scope")
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.span_label(
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self.span,
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format!(
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"lifetime `{}` is part of concrete type but not used in \
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parameter list of the `impl Trait` type alias",
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r
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),
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)
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.emit();
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self.tcx().lifetimes.re_static
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}
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}
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}
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fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
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match *ty.kind() {
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ty::Closure(def_id, substs) => {
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// I am a horrible monster and I pray for death. When
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// we encounter a closure here, it is always a closure
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// from within the function that we are currently
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// type-checking -- one that is now being encapsulated
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// in an opaque type. Ideally, we would
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// go through the types/lifetimes that it references
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// and treat them just like we would any other type,
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// which means we would error out if we find any
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// reference to a type/region that is not in the
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// "reverse map".
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//
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// **However,** in the case of closures, there is a
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// somewhat subtle (read: hacky) consideration. The
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// problem is that our closure types currently include
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// all the lifetime parameters declared on the
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// enclosing function, even if they are unused by the
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// closure itself. We can't readily filter them out,
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// so here we replace those values with `'empty`. This
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// can't really make a difference to the rest of the
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// compiler; those regions are ignored for the
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// outlives relation, and hence don't affect trait
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// selection or auto traits, and they are erased
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// during codegen.
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let generics = self.tcx.generics_of(def_id);
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let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| {
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if index < generics.parent_count {
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// Accommodate missing regions in the parent kinds...
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self.fold_kind_mapping_missing_regions_to_empty(kind)
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} else {
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// ...but not elsewhere.
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self.fold_kind_normally(kind)
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}
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}));
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self.tcx.mk_closure(def_id, substs)
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}
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ty::Generator(def_id, substs, movability) => {
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let generics = self.tcx.generics_of(def_id);
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let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| {
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if index < generics.parent_count {
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// Accommodate missing regions in the parent kinds...
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self.fold_kind_mapping_missing_regions_to_empty(kind)
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} else {
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// ...but not elsewhere.
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self.fold_kind_normally(kind)
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}
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}));
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self.tcx.mk_generator(def_id, substs, movability)
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}
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ty::Param(param) => {
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// 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
|
||||
.struct_span_err(
|
||||
self.span,
|
||||
&format!(
|
||||
"const parameter `{}` is part of concrete type but not \
|
||||
used in parameter list for the `impl Trait` type alias",
|
||||
ct
|
||||
),
|
||||
)
|
||||
.emit();
|
||||
|
||||
self.tcx().const_error(ct.ty())
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
_ => ct,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
@ -37,5 +37,4 @@
|
||||
|
||||
pub mod autoderef;
|
||||
pub mod infer;
|
||||
pub mod opaque_types;
|
||||
pub mod traits;
|
||||
|
||||
@ -1,545 +0,0 @@
|
||||
use crate::traits;
|
||||
use crate::traits::error_reporting::InferCtxtExt as _;
|
||||
use crate::traits::TraitEngineExt as _;
|
||||
use rustc_data_structures::fx::FxHashMap;
|
||||
use rustc_hir::def_id::DefId;
|
||||
use rustc_hir::OpaqueTyOrigin;
|
||||
use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic;
|
||||
use rustc_infer::infer::{InferCtxt, TyCtxtInferExt as _};
|
||||
use rustc_infer::traits::{Obligation, ObligationCause, TraitEngine};
|
||||
use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
|
||||
use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts};
|
||||
use rustc_middle::ty::visit::TypeVisitable;
|
||||
use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, ToPredicate, Ty, TyCtxt};
|
||||
use rustc_span::Span;
|
||||
|
||||
pub trait InferCtxtExt<'tcx> {
|
||||
fn infer_opaque_definition_from_instantiation(
|
||||
&self,
|
||||
opaque_type_key: OpaqueTypeKey<'tcx>,
|
||||
instantiated_ty: OpaqueHiddenType<'tcx>,
|
||||
origin: OpaqueTyOrigin,
|
||||
) -> Ty<'tcx>;
|
||||
}
|
||||
|
||||
impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, '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
|
||||
/// definition -- that is, the inferred value of `Foo1<'x>` or
|
||||
/// `Foo2<'x>` that we would conceptually use in its definition:
|
||||
/// ```ignore (illustrative)
|
||||
/// type Foo1<'x> = impl Bar<'x> = AAA; // <-- this type AAA
|
||||
/// type Foo2<'x> = impl Bar<'x> = BBB; // <-- or this type BBB
|
||||
/// fn foo<'a, 'b>(..) -> (Foo1<'a>, Foo2<'b>) { .. }
|
||||
/// ```
|
||||
/// Note that these values are defined in terms of a distinct set of
|
||||
/// generic parameters (`'x` instead of `'a`) from C1 or C2. The main
|
||||
/// purpose of this function is to do that translation.
|
||||
///
|
||||
/// (*) C1 and C2 were introduced in the comments on
|
||||
/// `register_member_constraints`. Read that comment for more context.
|
||||
///
|
||||
/// # Parameters
|
||||
///
|
||||
/// - `def_id`, the `impl Trait` type
|
||||
/// - `substs`, the substs used to instantiate this opaque type
|
||||
/// - `instantiated_ty`, the inferred type C1 -- fully resolved, lifted version of
|
||||
/// `opaque_defn.concrete_ty`
|
||||
#[instrument(level = "debug", skip(self))]
|
||||
fn infer_opaque_definition_from_instantiation(
|
||||
&self,
|
||||
opaque_type_key: OpaqueTypeKey<'tcx>,
|
||||
instantiated_ty: OpaqueHiddenType<'tcx>,
|
||||
origin: OpaqueTyOrigin,
|
||||
) -> Ty<'tcx> {
|
||||
if self.is_tainted_by_errors() {
|
||||
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);
|
||||
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,
|
||||
def_id,
|
||||
map,
|
||||
instantiated_ty.ty,
|
||||
instantiated_ty.span,
|
||||
));
|
||||
debug!(?definition_ty);
|
||||
|
||||
if !check_opaque_type_parameter_valid(
|
||||
self.tcx,
|
||||
opaque_type_key,
|
||||
origin,
|
||||
instantiated_ty.span,
|
||||
) {
|
||||
return self.tcx.ty_error();
|
||||
}
|
||||
|
||||
// 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.as_local().unwrap());
|
||||
self.tcx.infer_ctxt().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);
|
||||
|
||||
// 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,
|
||||
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, id_substs),
|
||||
definition_ty,
|
||||
err,
|
||||
)
|
||||
.emit();
|
||||
}
|
||||
}
|
||||
|
||||
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);
|
||||
|
||||
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 {
|
||||
definition_ty
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn check_opaque_type_parameter_valid(
|
||||
tcx: TyCtxt<'_>,
|
||||
opaque_type_key: OpaqueTypeKey<'_>,
|
||||
origin: OpaqueTyOrigin,
|
||||
span: Span,
|
||||
) -> bool {
|
||||
match origin {
|
||||
// No need to check return position impl trait (RPIT)
|
||||
// because for type and const parameters they are correct
|
||||
// by construction: we convert
|
||||
//
|
||||
// fn foo<P0..Pn>() -> impl Trait
|
||||
//
|
||||
// into
|
||||
//
|
||||
// type Foo<P0...Pn>
|
||||
// fn foo<P0..Pn>() -> Foo<P0...Pn>.
|
||||
//
|
||||
// For lifetime parameters we convert
|
||||
//
|
||||
// fn foo<'l0..'ln>() -> impl Trait<'l0..'lm>
|
||||
//
|
||||
// into
|
||||
//
|
||||
// type foo::<'p0..'pn>::Foo<'q0..'qm>
|
||||
// fn foo<l0..'ln>() -> foo::<'static..'static>::Foo<'l0..'lm>.
|
||||
//
|
||||
// which would error here on all of the `'static` args.
|
||||
OpaqueTyOrigin::FnReturn(..) | OpaqueTyOrigin::AsyncFn(..) => return true,
|
||||
// Check these
|
||||
OpaqueTyOrigin::TyAlias => {}
|
||||
}
|
||||
let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
|
||||
let mut seen_params: FxHashMap<_, Vec<_>> = FxHashMap::default();
|
||||
for (i, arg) in opaque_type_key.substs.iter().enumerate() {
|
||||
let arg_is_param = match arg.unpack() {
|
||||
GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
|
||||
GenericArgKind::Lifetime(lt) if lt.is_static() => {
|
||||
tcx.sess
|
||||
.struct_span_err(span, "non-defining opaque type use in defining scope")
|
||||
.span_label(
|
||||
tcx.def_span(opaque_generics.param_at(i, tcx).def_id),
|
||||
"cannot use static lifetime; use a bound lifetime \
|
||||
instead or remove the lifetime parameter from the \
|
||||
opaque type",
|
||||
)
|
||||
.emit();
|
||||
return false;
|
||||
}
|
||||
GenericArgKind::Lifetime(lt) => {
|
||||
matches!(*lt, ty::ReEarlyBound(_) | ty::ReFree(_))
|
||||
}
|
||||
GenericArgKind::Const(ct) => matches!(ct.kind(), ty::ConstKind::Param(_)),
|
||||
};
|
||||
|
||||
if arg_is_param {
|
||||
seen_params.entry(arg).or_default().push(i);
|
||||
} else {
|
||||
// Prevent `fn foo() -> Foo<u32>` from being defining.
|
||||
let opaque_param = opaque_generics.param_at(i, tcx);
|
||||
tcx.sess
|
||||
.struct_span_err(span, "non-defining opaque type use in defining scope")
|
||||
.span_note(
|
||||
tcx.def_span(opaque_param.def_id),
|
||||
&format!(
|
||||
"used non-generic {} `{}` for generic parameter",
|
||||
opaque_param.kind.descr(),
|
||||
arg,
|
||||
),
|
||||
)
|
||||
.emit();
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
for (_, indices) in seen_params {
|
||||
if indices.len() > 1 {
|
||||
let descr = opaque_generics.param_at(indices[0], tcx).kind.descr();
|
||||
let spans: Vec<_> = indices
|
||||
.into_iter()
|
||||
.map(|i| tcx.def_span(opaque_generics.param_at(i, tcx).def_id))
|
||||
.collect();
|
||||
tcx.sess
|
||||
.struct_span_err(span, "non-defining opaque type use in defining scope")
|
||||
.span_note(spans, &format!("{} used multiple times", descr))
|
||||
.emit();
|
||||
return false;
|
||||
}
|
||||
}
|
||||
true
|
||||
}
|
||||
|
||||
struct ReverseMapper<'tcx> {
|
||||
tcx: TyCtxt<'tcx>,
|
||||
|
||||
opaque_type_def_id: DefId,
|
||||
map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
|
||||
map_missing_regions_to_empty: 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>,
|
||||
opaque_type_def_id: DefId,
|
||||
map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
|
||||
hidden_ty: Ty<'tcx>,
|
||||
span: Span,
|
||||
) -> Self {
|
||||
Self {
|
||||
tcx,
|
||||
opaque_type_def_id,
|
||||
map,
|
||||
map_missing_regions_to_empty: false,
|
||||
hidden_ty: Some(hidden_ty),
|
||||
span,
|
||||
}
|
||||
}
|
||||
|
||||
fn fold_kind_mapping_missing_regions_to_empty(
|
||||
&mut self,
|
||||
kind: GenericArg<'tcx>,
|
||||
) -> GenericArg<'tcx> {
|
||||
assert!(!self.map_missing_regions_to_empty);
|
||||
self.map_missing_regions_to_empty = true;
|
||||
let kind = kind.fold_with(self);
|
||||
self.map_missing_regions_to_empty = false;
|
||||
kind
|
||||
}
|
||||
|
||||
fn fold_kind_normally(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
|
||||
assert!(!self.map_missing_regions_to_empty);
|
||||
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::ReEmpty(ty::UniverseIndex::ROOT) => {}
|
||||
|
||||
ty::ReEmpty(_) | 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.opaque_type_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.map_missing_regions_to_empty => self.tcx.lifetimes.re_root_empty,
|
||||
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.opaque_type_def_id),
|
||||
hidden_ty,
|
||||
r,
|
||||
)
|
||||
.emit();
|
||||
}
|
||||
self.tcx.lifetimes.re_root_empty
|
||||
}
|
||||
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_mapping_missing_regions_to_empty(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_mapping_missing_regions_to_empty(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
|
||||
.struct_span_err(
|
||||
self.span,
|
||||
&format!(
|
||||
"const parameter `{}` is part of concrete type but not \
|
||||
used in parameter list for the `impl Trait` type alias",
|
||||
ct
|
||||
),
|
||||
)
|
||||
.emit();
|
||||
|
||||
self.tcx().const_error(ct.ty())
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
_ => ct,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Given a set of predicates that apply to an object type, returns
|
||||
/// the region bounds that the (erased) `Self` type must
|
||||
/// outlive. Precisely *because* the `Self` type is erased, the
|
||||
/// parameter `erased_self_ty` must be supplied to indicate what type
|
||||
/// has been used to represent `Self` in the predicates
|
||||
/// themselves. This should really be a unique type; `FreshTy(0)` is a
|
||||
/// popular choice.
|
||||
///
|
||||
/// N.B., in some cases, particularly around higher-ranked bounds,
|
||||
/// this function returns a kind of conservative approximation.
|
||||
/// That is, all regions returned by this function are definitely
|
||||
/// required, but there may be other region bounds that are not
|
||||
/// returned, as well as requirements like `for<'a> T: 'a`.
|
||||
///
|
||||
/// Requires that trait definitions have been processed so that we can
|
||||
/// elaborate predicates and walk supertraits.
|
||||
#[instrument(skip(tcx, predicates), level = "debug")]
|
||||
pub(crate) fn required_region_bounds<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
erased_self_ty: Ty<'tcx>,
|
||||
predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
|
||||
) -> Vec<ty::Region<'tcx>> {
|
||||
assert!(!erased_self_ty.has_escaping_bound_vars());
|
||||
|
||||
traits::elaborate_predicates(tcx, predicates)
|
||||
.filter_map(|obligation| {
|
||||
debug!(?obligation);
|
||||
match obligation.predicate.kind().skip_binder() {
|
||||
ty::PredicateKind::Projection(..)
|
||||
| ty::PredicateKind::Trait(..)
|
||||
| ty::PredicateKind::Subtype(..)
|
||||
| ty::PredicateKind::Coerce(..)
|
||||
| ty::PredicateKind::WellFormed(..)
|
||||
| ty::PredicateKind::ObjectSafe(..)
|
||||
| ty::PredicateKind::ClosureKind(..)
|
||||
| ty::PredicateKind::RegionOutlives(..)
|
||||
| ty::PredicateKind::ConstEvaluatable(..)
|
||||
| ty::PredicateKind::ConstEquate(..)
|
||||
| ty::PredicateKind::TypeWellFormedFromEnv(..) => None,
|
||||
ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ref t, ref r)) => {
|
||||
// Search for a bound of the form `erased_self_ty
|
||||
// : 'a`, but be wary of something like `for<'a>
|
||||
// erased_self_ty : 'a` (we interpret a
|
||||
// higher-ranked bound like that as 'static,
|
||||
// though at present the code in `fulfill.rs`
|
||||
// considers such bounds to be unsatisfiable, so
|
||||
// it's kind of a moot point since you could never
|
||||
// construct such an object, but this seems
|
||||
// correct even if that code changes).
|
||||
if t == &erased_self_ty && !r.has_escaping_bound_vars() {
|
||||
Some(*r)
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
}
|
||||
})
|
||||
.collect()
|
||||
}
|
||||
@ -1,5 +1,4 @@
|
||||
use crate::infer::InferCtxt;
|
||||
use crate::opaque_types::required_region_bounds;
|
||||
use crate::traits;
|
||||
use rustc_hir as hir;
|
||||
use rustc_hir::def_id::DefId;
|
||||
@ -810,3 +809,63 @@ pub fn object_region_bounds<'tcx>(
|
||||
|
||||
required_region_bounds(tcx, open_ty, predicates)
|
||||
}
|
||||
|
||||
/// Given a set of predicates that apply to an object type, returns
|
||||
/// the region bounds that the (erased) `Self` type must
|
||||
/// outlive. Precisely *because* the `Self` type is erased, the
|
||||
/// parameter `erased_self_ty` must be supplied to indicate what type
|
||||
/// has been used to represent `Self` in the predicates
|
||||
/// themselves. This should really be a unique type; `FreshTy(0)` is a
|
||||
/// popular choice.
|
||||
///
|
||||
/// N.B., in some cases, particularly around higher-ranked bounds,
|
||||
/// this function returns a kind of conservative approximation.
|
||||
/// That is, all regions returned by this function are definitely
|
||||
/// required, but there may be other region bounds that are not
|
||||
/// returned, as well as requirements like `for<'a> T: 'a`.
|
||||
///
|
||||
/// Requires that trait definitions have been processed so that we can
|
||||
/// elaborate predicates and walk supertraits.
|
||||
#[instrument(skip(tcx, predicates), level = "debug")]
|
||||
pub(crate) fn required_region_bounds<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
erased_self_ty: Ty<'tcx>,
|
||||
predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
|
||||
) -> Vec<ty::Region<'tcx>> {
|
||||
assert!(!erased_self_ty.has_escaping_bound_vars());
|
||||
|
||||
traits::elaborate_predicates(tcx, predicates)
|
||||
.filter_map(|obligation| {
|
||||
debug!(?obligation);
|
||||
match obligation.predicate.kind().skip_binder() {
|
||||
ty::PredicateKind::Projection(..)
|
||||
| ty::PredicateKind::Trait(..)
|
||||
| ty::PredicateKind::Subtype(..)
|
||||
| ty::PredicateKind::Coerce(..)
|
||||
| ty::PredicateKind::WellFormed(..)
|
||||
| ty::PredicateKind::ObjectSafe(..)
|
||||
| ty::PredicateKind::ClosureKind(..)
|
||||
| ty::PredicateKind::RegionOutlives(..)
|
||||
| ty::PredicateKind::ConstEvaluatable(..)
|
||||
| ty::PredicateKind::ConstEquate(..)
|
||||
| ty::PredicateKind::TypeWellFormedFromEnv(..) => None,
|
||||
ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ref t, ref r)) => {
|
||||
// Search for a bound of the form `erased_self_ty
|
||||
// : 'a`, but be wary of something like `for<'a>
|
||||
// erased_self_ty : 'a` (we interpret a
|
||||
// higher-ranked bound like that as 'static,
|
||||
// though at present the code in `fulfill.rs`
|
||||
// considers such bounds to be unsatisfiable, so
|
||||
// it's kind of a moot point since you could never
|
||||
// construct such an object, but this seems
|
||||
// correct even if that code changes).
|
||||
if t == &erased_self_ty && !r.has_escaping_bound_vars() {
|
||||
Some(*r)
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
}
|
||||
})
|
||||
.collect()
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user