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Make sure that outer opaques capture inner opaques's lifetimes even with precise capturing syntax

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This commit is contained in:
Michael Goulet 2024-10-16 12:17:21 -04:00
parent a2a1206811
commit 70746d078e
5 changed files with 102 additions and 69 deletions
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79
compiler/rustc_ast_lowering/src/lib.rs
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@ -268,8 +268,8 @@ impl ResolverAstLowering {
///
/// The extra lifetimes that appear from the parenthesized `Fn`-trait desugaring
/// should appear at the enclosing `PolyTraitRef`.
fn take_extra_lifetime_params(&mut self, id: NodeId) -> Vec<(Ident, NodeId, LifetimeRes)> {
self.extra_lifetime_params_map.remove(&id).unwrap_or_default()
fn extra_lifetime_params(&mut self, id: NodeId) -> Vec<(Ident, NodeId, LifetimeRes)> {
self.extra_lifetime_params_map.get(&id).cloned().unwrap_or_default()
}
}
@ -885,7 +885,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let mut generic_params: Vec<_> = self
.lower_generic_params_mut(generic_params, hir::GenericParamSource::Binder)
.collect();
let extra_lifetimes = self.resolver.take_extra_lifetime_params(binder);
let extra_lifetimes = self.resolver.extra_lifetime_params(binder);
debug!(?extra_lifetimes);
generic_params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
self.lifetime_res_to_generic_param(ident, node_id, res, hir::GenericParamSource::Binder)
@ -1495,62 +1495,25 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
// frequently opened issues show.
let opaque_ty_span = self.mark_span_with_reason(DesugaringKind::OpaqueTy, span, None);
let captured_lifetimes_to_duplicate = if let Some(args) =
// We only look for one `use<...>` syntax since we syntactially reject more than one.
bounds.iter().find_map(
|bound| match bound {
ast::GenericBound::Use(a, _) => Some(a),
_ => None,
},
) {
// We'll actually validate these later on; all we need is the list of
// lifetimes to duplicate during this portion of lowering.
args.iter()
.filter_map(|arg| match arg {
PreciseCapturingArg::Lifetime(lt) => Some(*lt),
PreciseCapturingArg::Arg(..) => None,
})
// Add in all the lifetimes mentioned in the bounds. We will error
// them out later, but capturing them here is important to make sure
// they actually get resolved in resolve_bound_vars.
.chain(lifetime_collector::lifetimes_in_bounds(self.resolver, bounds))
.collect()
} else {
match origin {
hir::OpaqueTyOrigin::TyAlias { .. } => {
// type alias impl trait and associated type position impl trait were
// decided to capture all in-scope lifetimes, which we collect for
// all opaques during resolution.
self.resolver
.take_extra_lifetime_params(opaque_ty_node_id)
.into_iter()
.map(|(ident, id, _)| Lifetime { id, ident })
.collect()
}
hir::OpaqueTyOrigin::FnReturn { in_trait_or_impl, .. } => {
if in_trait_or_impl.is_some()
|| self.tcx.features().lifetime_capture_rules_2024
|| span.at_least_rust_2024()
{
// return-position impl trait in trait was decided to capture all
// in-scope lifetimes, which we collect for all opaques during resolution.
self.resolver
.take_extra_lifetime_params(opaque_ty_node_id)
.into_iter()
.map(|(ident, id, _)| Lifetime { id, ident })
.collect()
} else {
// in fn return position, like the `fn test<'a>() -> impl Debug + 'a`
// example, we only need to duplicate lifetimes that appear in the
// bounds, since those are the only ones that are captured by the opaque.
lifetime_collector::lifetimes_in_bounds(self.resolver, bounds)
}
}
hir::OpaqueTyOrigin::AsyncFn { .. } => {
unreachable!("should be using `lower_async_fn_ret_ty`")
}
// Whether this opaque always captures lifetimes in scope.
// Right now, this is all RPITIT and TAITs, and when `lifetime_capture_rules_2024`
// is enabled. We don't check the span of the edition, since this is done
// on a per-opaque basis to account for nested opaques.
let always_capture_in_scope = match origin {
_ if self.tcx.features().lifetime_capture_rules_2024 => true,
hir::OpaqueTyOrigin::TyAlias { .. } => true,
hir::OpaqueTyOrigin::FnReturn { in_trait_or_impl, .. } => in_trait_or_impl.is_some(),
hir::OpaqueTyOrigin::AsyncFn { .. } => {
unreachable!("should be using `lower_coroutine_fn_ret_ty`")
}
};
let captured_lifetimes_to_duplicate = lifetime_collector::lifetimes_for_opaque(
self.resolver,
always_capture_in_scope,
opaque_ty_node_id,
bounds,
span,
);
debug!(?captured_lifetimes_to_duplicate);
// Feature gate for RPITIT + use<..>
@ -1920,7 +1883,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let captured_lifetimes = self
.resolver
.take_extra_lifetime_params(opaque_ty_node_id)
.extra_lifetime_params(opaque_ty_node_id)
.into_iter()
.map(|(ident, id, _)| Lifetime { id, ident })
.collect();