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Add bidirectional where clauses on RPITIT synthesized GATs

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This commit is contained in:
Santiago Pastorino 2023-06-21 19:09:18 -03:00
parent d70deac161
commit 4925b57782
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GPG Key ID: 8131A24E0C79EFAF
6 changed files with 92 additions and 36 deletions
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50
compiler/rustc_ast_lowering/src/lib.rs
View File

@ -1568,14 +1568,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
// This creates HIR lifetime arguments as `hir::GenericArg`, in the given example `type
// TestReturn<'a, T, 'x> = impl Debug + 'x`, it creates a collection containing `&['x]`.
let lifetimes: Vec<_> = collected_lifetimes
let lifetime_mapping: Vec<_> = collected_lifetimes
.iter()
.map(|(_, lifetime)| {
.map(|(node_id, lifetime)| {
let id = self.next_node_id();
self.new_named_lifetime(lifetime.id, id, lifetime.ident)
let lifetime = self.new_named_lifetime(lifetime.id, id, lifetime.ident);
let def_id = self.local_def_id(*node_id);
(lifetime, def_id)
})
.collect();
debug!(?lifetimes);
debug!(?lifetime_mapping);
self.with_hir_id_owner(opaque_ty_node_id, |lctx| {
// Install the remapping from old to new (if any):
@ -1626,6 +1628,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}),
bounds: hir_bounds,
origin,
lifetime_mapping: self.arena.alloc_from_iter(
lifetime_mapping.iter().map(|(lifetime, def_id)| (**lifetime, *def_id)),
),
in_trait,
};
debug!(?opaque_ty_item);
@ -1634,17 +1639,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
})
});
// This creates HIR lifetime arguments as `hir::GenericArg`, in the given example `type
// TestReturn<'a, T, 'x> = impl Debug + 'x`, it creates a collection containing `&['x]`.
let lifetimes = self.arena.alloc_from_iter(
lifetimes.into_iter().map(|lifetime| hir::GenericArg::Lifetime(lifetime)),
);
debug!(?lifetimes);
// `impl Trait` now just becomes `Foo<'a, 'b, ..>`.
hir::TyKind::OpaqueDef(
hir::ItemId { owner_id: hir::OwnerId { def_id: opaque_ty_def_id } },
lifetimes,
self.arena.alloc_from_iter(
lifetime_mapping.iter().map(|(lifetime, _)| hir::GenericArg::Lifetime(*lifetime)),
),
in_trait,
)
}
@ -1986,7 +1986,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let lifetime = Lifetime { id: outer_node_id, ident };
collected_lifetimes.push((inner_node_id, lifetime, Some(inner_res)));
}
debug!(?collected_lifetimes);
// We only want to capture the lifetimes that appear in the bounds. So visit the bounds to
@ -2007,19 +2006,23 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
debug!(?collected_lifetimes);
debug!(?new_remapping);
// This creates HIR lifetime arguments as `hir::GenericArg`, in the given example `type
// TestReturn<'a, T, 'x> = impl Debug + 'x`, it creates a collection containing `&['x]`.
let lifetimes: Vec<_> = collected_lifetimes
// This creates pairs of HIR lifetimes and def_ids. In the given example `type
// TestReturn<'a, T, 'x> = impl Debug + 'x`, it creates a collection containing the
// new lifetime of the RPIT 'x and the def_id of the lifetime 'x corresponding to
// `TestReturn`.
let lifetime_mapping: Vec<_> = collected_lifetimes
.iter()
.map(|(_, lifetime, res)| {
.map(|(node_id, lifetime, res)| {
let id = self.next_node_id();
let res = res.unwrap_or(
self.resolver.get_lifetime_res(lifetime.id).unwrap_or(LifetimeRes::Error),
);
self.new_named_lifetime_with_res(id, lifetime.ident, res)
let lifetime = self.new_named_lifetime_with_res(id, lifetime.ident, res);
let def_id = self.local_def_id(*node_id);
(lifetime, def_id)
})
.collect();
debug!(?lifetimes);
debug!(?lifetime_mapping);
self.with_hir_id_owner(opaque_ty_node_id, |this| {
// Install the remapping from old to new (if any):
@ -2086,6 +2089,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}),
bounds: arena_vec![this; future_bound],
origin: hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
lifetime_mapping: self.arena.alloc_from_iter(
lifetime_mapping.iter().map(|(lifetime, def_id)| (**lifetime, *def_id)),
),
in_trait,
};
@ -2109,9 +2115,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
//
// For the "output" lifetime parameters, we just want to
// generate `'_`.
let generic_args = self
.arena
.alloc_from_iter(lifetimes.iter().map(|lifetime| hir::GenericArg::Lifetime(*lifetime)));
let generic_args = self.arena.alloc_from_iter(
lifetime_mapping.iter().map(|(lifetime, _)| hir::GenericArg::Lifetime(*lifetime)),
);
// Create the `Foo<...>` reference itself. Note that the `type
// Foo = impl Trait` is, internally, created as a child of the

4
compiler/rustc_hir/src/hir.rs
View File

@ -2664,6 +2664,10 @@ pub struct OpaqueTy<'hir> {
pub generics: &'hir Generics<'hir>,
pub bounds: GenericBounds<'hir>,
pub origin: OpaqueTyOrigin,
// Opaques have duplicated lifetimes, this mapping connects the original lifetime with the copy
// so we can later generate bidirectional outlives predicates to enforce that these lifetimes
// stay in sync.
pub lifetime_mapping: &'hir [(Lifetime, LocalDefId)],
pub in_trait: bool,
}

58
compiler/rustc_hir_analysis/src/collect/predicates_of.rs
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@ -10,7 +10,7 @@ use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::intravisit::{self, Visitor};
use rustc_middle::ty::subst::InternalSubsts;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{GenericPredicates, Generics, ToPredicate};
use rustc_middle::ty::{GenericPredicates, Generics, ImplTraitInTraitData, ToPredicate};
use rustc_span::symbol::{sym, Ident};
use rustc_span::{Span, Symbol, DUMMY_SP};
@ -62,6 +62,54 @@ pub(super) fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredic
fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::GenericPredicates<'_> {
use rustc_hir::*;
match tcx.opt_rpitit_info(def_id.to_def_id()) {
Some(ImplTraitInTraitData::Trait { opaque_def_id, .. }) => {
let opaque_ty_id = tcx.hir().local_def_id_to_hir_id(opaque_def_id.expect_local());
let opaque_ty_node = tcx.hir().get(opaque_ty_id);
let Node::Item(&Item { kind: ItemKind::OpaqueTy(OpaqueTy { lifetime_mapping, .. }), .. }) = opaque_ty_node else {
bug!("unexpected {opaque_ty_node:?}")
};
let mut predicates = Vec::new();
compute_bidirectional_outlives_predicates(
tcx,
def_id,
lifetime_mapping.iter().map(|(lifetime, def_id)| {
(*lifetime, (*def_id, lifetime.ident.name, lifetime.ident.span))
}),
tcx.generics_of(def_id.to_def_id()),
&mut predicates,
);
return ty::GenericPredicates {
parent: Some(tcx.parent(def_id.to_def_id())),
predicates: tcx.arena.alloc_from_iter(predicates),
};
}
Some(ImplTraitInTraitData::Impl { fn_def_id }) => {
let assoc_item = tcx.associated_item(def_id);
let trait_assoc_predicates = tcx.predicates_of(assoc_item.trait_item_def_id.unwrap());
let impl_assoc_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
let impl_def_id = tcx.parent(fn_def_id);
let impl_trait_ref_substs =
tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder().substs;
let impl_assoc_substs =
impl_assoc_identity_substs.rebase_onto(tcx, impl_def_id, impl_trait_ref_substs);
let impl_predicates = trait_assoc_predicates.instantiate_own(tcx, impl_assoc_substs);
return ty::GenericPredicates {
parent: Some(impl_def_id),
predicates: tcx.arena.alloc_from_iter(impl_predicates),
};
}
None => {}
}
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
let node = tcx.hir().get(hir_id);
@ -298,7 +346,13 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
.filter(|(_, dup)| matches!(dup.kind, hir::GenericParamKind::Lifetime { .. }))
.map(|(lifetime, dup)| (lifetime, (dup.def_id, dup.name.ident().name, dup.span)));
bidirectional_lifetime_predicates(tcx, def_id, lifetime_mapping, generics, &mut predicates);
compute_bidirectional_outlives_predicates(
tcx,
def_id,
lifetime_mapping,
generics,
&mut predicates,
);
debug!(?predicates);
}

12
compiler/rustc_ty_utils/src/assoc.rs
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@ -340,12 +340,6 @@ fn associated_type_for_impl_trait_in_trait(
}
});
// There are no predicates for the synthesized associated type.
trait_assoc_ty.explicit_predicates_of(ty::GenericPredicates {
parent: Some(trait_def_id.to_def_id()),
predicates: &[],
});
// There are no inferred outlives for the synthesized associated type.
trait_assoc_ty.inferred_outlives_of(&[]);
@ -424,12 +418,6 @@ fn associated_type_for_impl_trait_in_impl(
}
});
// There are no predicates for the synthesized associated type.
impl_assoc_ty.explicit_predicates_of(ty::GenericPredicates {
parent: Some(impl_local_def_id.to_def_id()),
predicates: &[],
});
// There are no inferred outlives for the synthesized associated type.
impl_assoc_ty.inferred_outlives_of(&[]);

2
tests/ui/async-await/in-trait/async-lifetimes-and-bounds.rs
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@ -1,5 +1,7 @@
// check-pass
// edition: 2021
// [next] compile-flags: -Zlower-impl-trait-in-trait-to-assoc-ty
// revisions: current next
#![feature(async_fn_in_trait)]
#![allow(incomplete_features)]

2
tests/ui/async-await/in-trait/async-lifetimes.rs
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@ -1,5 +1,7 @@
// check-pass
// edition: 2021
// [next] compile-flags: -Zlower-impl-trait-in-trait-to-assoc-ty
// revisions: current next
#![feature(async_fn_in_trait)]
#![allow(incomplete_features)]