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Rollup merge of #122103 - compiler-errors:taits-capture-everything, r=oli-obk

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Make TAITs and ATPITs capture late-bound lifetimes in scope

This generalizes the behavior that RPITs have, where they duplicate their in-scope lifetimes so that they will always *reify* late-bound lifetimes that they capture. This allows TAITs and ATPITs to properly error when they capture in-scope late-bound lifetimes.

r? `@oli-obk` cc `@aliemjay`

Fixes #122093 and therefore https://github.com/rust-lang/rust/pull/120700#issuecomment-1981213868
This commit is contained in:
Matthias Krüger 2024-03-08 08:19:20 +01:00 • committed by GitHub
commit d4d18d240b
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21 changed files with 148 additions and 185 deletions
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21
compiler/rustc_hir_analysis/src/check/check.rs
View file

@ -339,8 +339,9 @@ fn check_opaque_meets_bounds<'tcx>(
origin: &hir::OpaqueTyOrigin,
) -> Result<(), ErrorGuaranteed> {
let defining_use_anchor = match *origin {
hir::OpaqueTyOrigin::FnReturn(did) | hir::OpaqueTyOrigin::AsyncFn(did) => did,
hir::OpaqueTyOrigin::TyAlias { .. } => tcx.impl_trait_parent(def_id),
hir::OpaqueTyOrigin::FnReturn(did)
| hir::OpaqueTyOrigin::AsyncFn(did)
| hir::OpaqueTyOrigin::TyAlias { parent: did, .. } => did,
};
let param_env = tcx.param_env(defining_use_anchor);
@ -351,14 +352,14 @@ fn check_opaque_meets_bounds<'tcx>(
let ocx = ObligationCtxt::new(&infcx);
let args = match *origin {
hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
GenericArgs::identity_for_item(tcx, parent).extend_to(
tcx,
def_id.to_def_id(),
|param, _| tcx.map_rpit_lifetime_to_fn_lifetime(param.def_id.expect_local()).into(),
)
}
hir::OpaqueTyOrigin::TyAlias { .. } => GenericArgs::identity_for_item(tcx, def_id),
hir::OpaqueTyOrigin::FnReturn(parent)
| hir::OpaqueTyOrigin::AsyncFn(parent)
| hir::OpaqueTyOrigin::TyAlias { parent, .. } => GenericArgs::identity_for_item(
tcx, parent,
)
.extend_to(tcx, def_id.to_def_id(), |param, _| {
tcx.map_opaque_lifetime_to_parent_lifetime(param.def_id.expect_local()).into()
}),
};
let opaque_ty = Ty::new_opaque(tcx, def_id.to_def_id(), args);

2
compiler/rustc_hir_analysis/src/collect/predicates_of.rs
View file

@ -339,7 +339,7 @@ fn compute_bidirectional_outlives_predicates<'tcx>(
predicates: &mut Vec<(ty::Clause<'tcx>, Span)>,
) {
for param in opaque_own_params {
let orig_lifetime = tcx.map_rpit_lifetime_to_fn_lifetime(param.def_id.expect_local());
let orig_lifetime = tcx.map_opaque_lifetime_to_parent_lifetime(param.def_id.expect_local());
if let ty::ReEarlyParam(..) = *orig_lifetime {
let dup_lifetime = ty::Region::new_early_param(
tcx,

56
compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
View file

@ -514,38 +514,11 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
// These sorts of items have no lifetime parameters at all.
intravisit::walk_item(self, item);
}
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::TyAlias { .. },
..
}) => {
// Opaque types are visited when we visit the
// `TyKind::OpaqueDef`, so that they have the lifetimes from
// their parent opaque_ty in scope.
//
// The core idea here is that since OpaqueTys are generated with the impl Trait as
// their owner, we can keep going until we find the Item that owns that. We then
// conservatively add all resolved lifetimes. Otherwise we run into problems in
// cases like `type Foo<'a> = impl Bar<As = impl Baz + 'a>`.
let parent_item = self.tcx.hir().get_parent_item(item.hir_id());
let resolved_lifetimes: &ResolveBoundVars =
self.tcx.resolve_bound_vars(parent_item);
// We need to add *all* deps, since opaque tys may want them from *us*
for (&owner, defs) in resolved_lifetimes.defs.iter() {
defs.iter().for_each(|(&local_id, region)| {
self.map.defs.insert(hir::HirId { owner, local_id }, *region);
});
}
for (&owner, late_bound_vars) in resolved_lifetimes.late_bound_vars.iter() {
late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| {
self.record_late_bound_vars(
hir::HirId { owner, local_id },
late_bound_vars.clone(),
);
});
}
}
hir::ItemKind::OpaqueTy(&hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent),
origin:
hir::OpaqueTyOrigin::FnReturn(parent)
| hir::OpaqueTyOrigin::AsyncFn(parent)
| hir::OpaqueTyOrigin::TyAlias { parent, .. },
generics,
..
}) => {
@ -683,26 +656,7 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
// the opaque_ty generics
let opaque_ty = self.tcx.hir().item(item_id);
match &opaque_ty.kind {
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::TyAlias { .. },
..
}) => {
intravisit::walk_ty(self, ty);
// Elided lifetimes and late-bound lifetimes (from the parent)
// are not allowed in non-return position impl Trait
let scope = Scope::LateBoundary {
s: &Scope::TraitRefBoundary { s: self.scope },
what: "type alias impl trait",
};
self.with(scope, |this| intravisit::walk_item(this, opaque_ty));
return;
}
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
..
}) => {}
hir::ItemKind::OpaqueTy(hir::OpaqueTy { origin: _, .. }) => {}
i => bug!("`impl Trait` pointed to non-opaque type?? {:#?}", i),
};

4
compiler/rustc_hir_analysis/src/collect/type_of.rs
View file

@ -553,11 +553,11 @@ pub(super) fn type_of_opaque(
Ok(ty::EarlyBinder::bind(match tcx.hir_node_by_def_id(def_id) {
Node::Item(item) => match item.kind {
ItemKind::OpaqueTy(OpaqueTy {
origin: hir::OpaqueTyOrigin::TyAlias { in_assoc_ty: false },
origin: hir::OpaqueTyOrigin::TyAlias { in_assoc_ty: false, .. },
..
}) => opaque::find_opaque_ty_constraints_for_tait(tcx, def_id),
ItemKind::OpaqueTy(OpaqueTy {
origin: hir::OpaqueTyOrigin::TyAlias { in_assoc_ty: true },
origin: hir::OpaqueTyOrigin::TyAlias { in_assoc_ty: true, .. },
..
}) => opaque::find_opaque_ty_constraints_for_impl_trait_in_assoc_type(tcx, def_id),
// Opaque types desugared from `impl Trait`.

10
compiler/rustc_hir_analysis/src/variance/mod.rs
View file

@ -125,15 +125,7 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
// By default, RPIT are invariant wrt type and const generics, but they are bivariant wrt
// lifetime generics.
let variances = std::iter::repeat(ty::Invariant).take(generics.count());
let mut variances: Vec<_> = match tcx.opaque_type_origin(item_def_id) {
rustc_hir::OpaqueTyOrigin::FnReturn(_) | rustc_hir::OpaqueTyOrigin::AsyncFn(_) => {
variances.collect()
}
// But TAIT are invariant for all generics
rustc_hir::OpaqueTyOrigin::TyAlias { .. } => return tcx.arena.alloc_from_iter(variances),
};
let mut variances = vec![ty::Invariant; generics.count()];
// Mark all lifetimes from parent generics as unused (Bivariant).
// This will be overridden later if required.