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|
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_hir::{def::DefKind, def_id::LocalDefId};
use rustc_middle::ty::util::{CheckRegions, NotUniqueParam};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
use rustc_span::Span;
use rustc_type_ir::AliasKind;
use std::ops::ControlFlow;
use crate::errors::{DuplicateArg, NotParam};
struct OpaqueTypeCollector<'tcx> {
tcx: TyCtxt<'tcx>,
opaques: Vec<LocalDefId>,
/// The `DefId` of the item which we are collecting opaque types for.
item: LocalDefId,
/// Avoid infinite recursion due to recursive declarations.
seen: FxHashSet<LocalDefId>,
}
impl<'tcx> OpaqueTypeCollector<'tcx> {
fn collect(
tcx: TyCtxt<'tcx>,
item: LocalDefId,
val: ty::Binder<'tcx, impl TypeVisitable<TyCtxt<'tcx>>>,
) -> Vec<LocalDefId> {
let mut collector = Self { tcx, opaques: Vec::new(), item, seen: Default::default() };
val.skip_binder().visit_with(&mut collector);
collector.opaques
}
fn span(&self) -> Span {
self.tcx.def_span(self.item)
}
fn parent(&self) -> Option<LocalDefId> {
match self.tcx.def_kind(self.item) {
DefKind::Fn => None,
DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => {
Some(self.tcx.local_parent(self.item))
}
other => span_bug!(
self.tcx.def_span(self.item),
"unhandled item with opaque types: {other:?}"
),
}
}
}
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
type BreakTy = ErrorGuaranteed;
#[instrument(skip(self), ret, level = "trace")]
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<ErrorGuaranteed> {
match t.kind() {
ty::Alias(AliasKind::Opaque, alias_ty) if alias_ty.def_id.is_local() => {
if !self.seen.insert(alias_ty.def_id.expect_local()) {
return ControlFlow::Continue(());
}
match self.tcx.uses_unique_generic_params(alias_ty.substs, CheckRegions::Bound) {
Ok(()) => {
// FIXME: implement higher kinded lifetime bounds on nested opaque types. They are not
// supported at all, so this is sound to do, but once we want to support them, you'll
// start seeing the error below.
self.opaques.push(alias_ty.def_id.expect_local());
// Collect opaque types nested within the associated type bounds of this opaque type.
for (pred, _span) in self
.tcx
.explicit_item_bounds(alias_ty.def_id)
.subst_iter_copied(self.tcx, alias_ty.substs)
{
trace!(?pred);
pred.visit_with(self)?;
}
ControlFlow::Continue(())
}
Err(NotUniqueParam::NotParam(arg)) => {
let err = self.tcx.sess.emit_err(NotParam {
arg,
span: self.span(),
opaque_span: self.tcx.def_span(alias_ty.def_id),
});
ControlFlow::Break(err)
}
Err(NotUniqueParam::DuplicateParam(arg)) => {
let err = self.tcx.sess.emit_err(DuplicateArg {
arg,
span: self.span(),
opaque_span: self.tcx.def_span(alias_ty.def_id),
});
ControlFlow::Break(err)
}
}
}
ty::Alias(AliasKind::Projection, alias_ty) => {
if let Some(parent) = self.parent() {
trace!(?alias_ty);
let (trait_ref, own_substs) = alias_ty.trait_ref_and_own_substs(self.tcx);
trace!(?trait_ref, ?own_substs);
// This avoids having to do normalization of `Self::AssocTy` by only
// supporting the case of a method defining opaque types from assoc types
// in the same impl block.
if trait_ref.self_ty() == self.tcx.type_of(parent).subst_identity() {
for assoc in self.tcx.associated_items(parent).in_definition_order() {
trace!(?assoc);
if assoc.trait_item_def_id == Some(alias_ty.def_id) {
// We reconstruct the generic args of the associated type within the impl
// from the impl's generics and the generic args passed to the type via the
// projection.
let substs = ty::InternalSubsts::identity_for_item(
self.tcx,
parent.to_def_id(),
);
trace!(?substs);
let substs: Vec<_> =
substs.iter().chain(own_substs.iter().copied()).collect();
trace!(?substs);
// Find opaque types in this associated type.
return self
.tcx
.type_of(assoc.def_id)
.subst(self.tcx, &substs)
.visit_with(self);
}
}
}
}
t.super_visit_with(self)
}
_ => t.super_visit_with(self),
}
}
}
fn opaque_types_defined_by<'tcx>(tcx: TyCtxt<'tcx>, item: LocalDefId) -> &'tcx [LocalDefId] {
let kind = tcx.def_kind(item);
trace!(?kind);
// FIXME(type_alias_impl_trait): This is definitely still wrong except for RPIT and impl trait in assoc types.
match kind {
// We're also doing this for `AssocTy` for the wf checks in `check_opaque_meets_bounds`
DefKind::Fn | DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => {
let defined_opaques = match kind {
DefKind::Fn => {
OpaqueTypeCollector::collect(tcx, item, tcx.fn_sig(item).subst_identity())
}
DefKind::AssocFn => {
OpaqueTypeCollector::collect(tcx, item, tcx.fn_sig(item).subst_identity())
}
DefKind::AssocTy | DefKind::AssocConst => OpaqueTypeCollector::collect(
tcx,
item,
ty::Binder::dummy(tcx.type_of(item).subst_identity()),
),
_ => unreachable!(),
};
tcx.arena.alloc_from_iter(defined_opaques)
}
DefKind::Mod
| DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Trait
| DefKind::TyAlias
| DefKind::ForeignTy
| DefKind::TraitAlias
| DefKind::TyParam
| DefKind::Const
| DefKind::ConstParam
| DefKind::Static(_)
| DefKind::Ctor(_, _)
| DefKind::Macro(_)
| DefKind::ExternCrate
| DefKind::Use
| DefKind::ForeignMod
| DefKind::AnonConst
| DefKind::InlineConst
| DefKind::OpaqueTy
| DefKind::ImplTraitPlaceholder
| DefKind::Field
| DefKind::LifetimeParam
| DefKind::GlobalAsm
| DefKind::Impl { .. }
| DefKind::Closure
| DefKind::Generator => &[],
}
}
pub(super) fn provide(providers: &mut ty::query::Providers) {
*providers = ty::query::Providers { opaque_types_defined_by, ..*providers };
}
|
