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This commit is contained in:
Camille GILLOT 2024-10-26 17:34:28 +00:00
parent d804ef8be8
commit 27c958fb44
4 changed files with 2 additions and 158 deletions
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151
compiler/rustc_ast_lowering/src/lifetime_collector.rs
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@ -1,151 +0,0 @@
use rustc_ast::visit::{self, BoundKind, LifetimeCtxt, Visitor};
use rustc_ast::{
GenericBound, GenericBounds, Lifetime, NodeId, PathSegment, PolyTraitRef, Ty, TyKind,
};
use rustc_data_structures::fx::FxIndexSet;
use rustc_hir::def::{DefKind, LifetimeRes, Res};
use rustc_middle::span_bug;
use rustc_middle::ty::ResolverAstLowering;
use rustc_span::Span;
use rustc_span::symbol::{Ident, kw};
use super::ResolverAstLoweringExt;
struct LifetimeCollectVisitor<'ast> {
resolver: &'ast mut ResolverAstLowering,
always_capture_in_scope: bool,
current_binders: Vec<NodeId>,
collected_lifetimes: FxIndexSet<Lifetime>,
}
impl<'ast> LifetimeCollectVisitor<'ast> {
fn new(resolver: &'ast mut ResolverAstLowering, always_capture_in_scope: bool) -> Self {
Self {
resolver,
always_capture_in_scope,
current_binders: Vec::new(),
collected_lifetimes: FxIndexSet::default(),
}
}
fn visit_opaque(&mut self, opaque_ty_node_id: NodeId, bounds: &'ast GenericBounds, span: Span) {
// If we're edition 2024 or within a TAIT or RPITIT, *and* there is no
// `use<>` statement to override the default capture behavior, then
// capture all of the in-scope lifetimes.
if (self.always_capture_in_scope || span.at_least_rust_2024())
&& bounds.iter().all(|bound| !matches!(bound, GenericBound::Use(..)))
{
for (ident, id, _) in self.resolver.extra_lifetime_params(opaque_ty_node_id) {
self.record_lifetime_use(Lifetime { id, ident });
}
}
// We also recurse on the bounds to make sure we capture all the lifetimes
// mentioned in the bounds. These may disagree with the `use<>` list, in which
// case we will error on these later. We will also recurse to visit any
// nested opaques, which may *implicitly* capture lifetimes.
for bound in bounds {
self.visit_param_bound(bound, BoundKind::Bound);
}
}
fn record_lifetime_use(&mut self, lifetime: Lifetime) {
match self.resolver.get_lifetime_res(lifetime.id).unwrap_or(LifetimeRes::Error) {
LifetimeRes::Param { binder, .. } | LifetimeRes::Fresh { binder, .. } => {
if !self.current_binders.contains(&binder) {
self.collected_lifetimes.insert(lifetime);
}
}
LifetimeRes::Static { .. } | LifetimeRes::Error => {
self.collected_lifetimes.insert(lifetime);
}
LifetimeRes::Infer => {}
res => {
let bug_msg = format!(
"Unexpected lifetime resolution {:?} for {:?} at {:?}",
res, lifetime.ident, lifetime.ident.span
);
span_bug!(lifetime.ident.span, "{}", bug_msg);
}
}
}
/// This collect lifetimes that are elided, for nodes like `Foo<T>` where there are no explicit
/// lifetime nodes. Is equivalent to having "pseudo" nodes introduced for each of the node ids
/// in the list start..end.
fn record_elided_anchor(&mut self, node_id: NodeId, span: Span) {
if let Some(LifetimeRes::ElidedAnchor { start, end }) =
self.resolver.get_lifetime_res(node_id)
{
for i in start..end {
let lifetime = Lifetime { id: i, ident: Ident::new(kw::UnderscoreLifetime, span) };
self.record_lifetime_use(lifetime);
}
}
}
}
impl<'ast> Visitor<'ast> for LifetimeCollectVisitor<'ast> {
fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, _: LifetimeCtxt) {
self.record_lifetime_use(*lifetime);
}
fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
self.record_elided_anchor(path_segment.id, path_segment.ident.span);
visit::walk_path_segment(self, path_segment);
}
fn visit_poly_trait_ref(&mut self, t: &'ast PolyTraitRef) {
self.current_binders.push(t.trait_ref.ref_id);
visit::walk_poly_trait_ref(self, t);
self.current_binders.pop();
}
fn visit_ty(&mut self, t: &'ast Ty) {
match &t.kind {
TyKind::Path(None, _) => {
// We can sometimes encounter bare trait objects
// which are represented in AST as paths.
if let Some(partial_res) = self.resolver.get_partial_res(t.id)
&& let Some(Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) =
partial_res.full_res()
{
self.current_binders.push(t.id);
visit::walk_ty(self, t);
self.current_binders.pop();
} else {
visit::walk_ty(self, t);
}
}
TyKind::BareFn(_) => {
self.current_binders.push(t.id);
visit::walk_ty(self, t);
self.current_binders.pop();
}
TyKind::Ref(None, _) | TyKind::PinnedRef(None, _) => {
self.record_elided_anchor(t.id, t.span);
visit::walk_ty(self, t);
}
TyKind::ImplTrait(opaque_ty_node_id, bounds) => {
self.visit_opaque(*opaque_ty_node_id, bounds, t.span)
}
_ => {
visit::walk_ty(self, t);
}
}
}
}
pub(crate) fn lifetimes_for_opaque(
resolver: &mut ResolverAstLowering,
always_capture_in_scope: bool,
opaque_ty_node_id: NodeId,
bounds: &GenericBounds,
span: Span,
) -> FxIndexSet<Lifetime> {
let mut visitor = LifetimeCollectVisitor::new(resolver, always_capture_in_scope);
visitor.visit_opaque(opaque_ty_node_id, bounds, span);
visitor.collected_lifetimes
}

5
compiler/rustc_hir/src/hir.rs
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@ -2849,11 +2849,6 @@ pub enum TyKind<'hir> {
/// Type parameters may be stored in each `PathSegment`.
Path(QPath<'hir>),
/// An opaque type definition itself. This is only used for `impl Trait`.
///
/// The generic argument list contains the lifetimes (and in the future
/// possibly parameters) that are actually bound on the `impl Trait`.
///
/// The last parameter specifies whether this opaque appears in a trait definition.
OpaqueDef(&'hir OpaqueTy<'hir>),
/// A trait object type `Bound1 + Bound2 + Bound3`
/// where `Bound` is a trait or a lifetime.

2
compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
View File

@ -156,7 +156,7 @@ enum Scope<'a> {
/// `fn foo<'a>() -> impl MyTrait<'a> { ... }`
///
/// HIR tells us that `'a` refer to the lifetime bound on `foo`.
/// However, typeck and borrowck for opaques are work based on using a new generics type.
/// However, typeck and borrowck for opaques work based on using a new generic type.
/// `type MyAnonTy<'b> = impl MyTrait<'b>;`
///
/// This scope collects the mapping `'a -> 'b`.

2
compiler/rustc_resolve/src/late.rs
View File

@ -841,7 +841,7 @@ fn visit_ty(&mut self, ty: &'ast Ty) {
self.r.record_partial_res(ty.id, PartialRes::new(res));
visit::walk_ty(self, ty)
}
TyKind::ImplTrait(_, _) => {
TyKind::ImplTrait(..) => {
let candidates = self.lifetime_elision_candidates.take();
visit::walk_ty(self, ty);
self.lifetime_elision_candidates = candidates;