delegation: split resolution and lowering#157296

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rust-bors merged 1 commit into from
Jun 4, 2026
+144 −100
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delegation: split resolution and lowering #157296

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6 changes: 6 additions & 0 deletions compiler/rustc_ast/src/ast.rs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
pub from_glob: bool,
}

impl Delegation {
pub fn last_segment_span(&self) -> Span {
self.path.segments.last().unwrap().ident.span
}
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
List(ThinVec<(Ident, Option<Ident>)>),
Expand Down
174 changes: 96 additions & 78 deletions compiler/rustc_ast_lowering/src/delegation.rs
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Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
ResolverAstLoweringExt,
ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
},
];

pub(crate) fn delegations_resolutions(
tcx: TyCtxt<'_>,
_: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
let krate = tcx.hir_crate(());

let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

// FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
// as it is too bad to reindex whole crate on each delegation lowering.
let ast_index = index_crate(resolver, ast_crate);

let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

for &def_id in &krate.delayed_ids {
let delegation = ast_index[def_id].delegation().expect("processing delegations");
let span = delegation.last_segment_span();

if let Some(info) = resolver.delegation_info(def_id) {
let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
result.insert(def_id, res.flatten());
} else {
tcx.dcx().span_delayed_bug(
span,
format!("delegation resolution record was not found for {def_id:?}"),
);
}
}

result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
let mut visited: FxHashSet<DefId> = Default::default();

let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

loop {
visited.insert(def_id);

// If def_id is in local crate and it corresponds to another delegation
// it means that we refer to another delegation as a callee, so in order to obtain
// a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
if let Some(local_id) = def_id.as_local()
&& let Some(info) = resolver.delegation_info(local_id)
&& let Ok(id) = info.resolution_id
{
def_id = id;
if visited.contains(&def_id) {
return Err(match visited.len() {
1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
_ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
});
}
} else {
return Ok(());
}
}
}

impl<'hir> LoweringContext<'_, 'hir> {
fn is_method(&self, def_id: DefId, span: Span) -> bool {
match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
delegation: &Delegation,
item_id: NodeId,
) -> DelegationResults<'hir> {
let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
self.dcx().span_delayed_bug(
span,
format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
return self.generate_delegation_error(span, delegation);
};

match sig_id {
Ok(sig_id) => {
self.add_attrs_if_needed(span, sig_id);
self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

let (body_id, call_expr_id) = self.lower_delegation_body(
delegation,
is_method,
param_count,
&mut generics,
span,
);
let (body_id, call_expr_id) =
self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});

DelegationResults { body_id, sig, ident, generics }
}
Err(_) => self.generate_delegation_error(span, delegation),
}
DelegationResults { body_id, sig, ident, generics }
}

fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
.collect::<Vec<_>>()
}

fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
let mut visited: FxHashSet<DefId> = Default::default();
let mut path: SmallVec<[DefId; 1]> = Default::default();

loop {
visited.insert(def_id);

path.push(def_id);

// If def_id is in local crate and it corresponds to another delegation
// it means that we refer to another delegation as a callee, so in order to obtain
// a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
if let Some(local_id) = def_id.as_local()
&& let Some(delegation_info) = self.resolver.delegation_info(local_id)
{
def_id = delegation_info.resolution_id;
if visited.contains(&def_id) {
// We encountered a cycle in the resolution, or delegation callee refers to non-existent
// entity, in this case emit an error.
return Err(match visited.len() {
1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
_ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
});
}
} else {
return Ok(path[0]);
}
}
}

fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
}
Expand Down
33 changes: 24 additions & 9 deletions compiler/rustc_ast_lowering/src/lib.rs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
providers.hir_crate = lower_to_hir;
providers.lower_delayed_owner = lower_delayed_owner;
providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
tcx: TyCtxt<'hir>,
resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
fn delegation(&self) -> Option<&ast::Delegation> {
match self {
AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
| AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
_ => None,
}
}
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
/// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
})
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
// Queries that borrow `resolver_for_lowering`.
tcx.ensure_done().output_filenames(());
tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

for def_id in ast_index.indices() {
match &ast_index[def_id] {
AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
| AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
delayed_ids.insert(def_id);
}
_ => lowerer.lower_node(def_id),
};
if ast_index[def_id].delegation().is_some() {
delayed_ids.insert(def_id);
} else {
lowerer.lower_node(def_id);
}
}

// Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
let krate = tcx.hir_crate(());

let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down
3 changes: 1 addition & 2 deletions compiler/rustc_interface/src/passes.rs
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Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
let providers = &mut Providers::default();
providers.queries.analysis = analysis;
providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
// `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
// as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
providers.queries.early_lint_checks = early_lint_checks;
providers.queries.env_var_os = env_var_os;
rustc_ast_lowering::provide(&mut providers.queries);
limits::provide(&mut providers.queries);
proc_macro_decls::provide(&mut providers.queries);
rustc_expand::provide(&mut providers.queries);
Expand Down
6 changes: 6 additions & 0 deletions compiler/rustc_middle/src/queries.rs
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Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
desc { "getting delegation user-specified args" }
}

query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
arena_cache
eval_always
desc { "getting delegations resolutions" }
}

/// Does lifetime resolution on items. Importantly, we can't resolve
/// lifetimes directly on things like trait methods, because of trait params.
/// See `rustc_resolve::late::lifetimes` for details.
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_middle/src/ty/mod.rs
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Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
/// Refers to the next element in a delegation resolution chain.
/// Usually points to the final resolution, as most "chains" are just
/// one step to a trait or an impl.
pub resolution_id: DefId,
pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down
20 changes: 10 additions & 10 deletions compiler/rustc_resolve/src/late.rs
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Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
this.visit_path(&delegation.path);
});

let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
let def_id = self
.r
.partial_res_map
.get(&resolution_id)
.get(&resolution_node_id)
.and_then(|r| r.expect_full_res().opt_def_id());
if let Some(resolution_id) = def_id {
self.r
.delegation_infos
.insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
} else {

let resolution_id = def_id.ok_or_else(|| {
self.r.tcx.dcx().span_delayed_bug(
delegation.path.span,
format!(
"LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
"LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
),
);
};
)
});

let info = DelegationInfo { resolution_id };
self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

let Some(body) = &delegation.body else { return };
self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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delegation: split resolution and lowering#157296

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 Merged

rust-bors
merged 1 commit into

from

Jun 4, 2026

+144

−100

 Merged


delegation: split resolution and lowering
#157296
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6 changes: 6 additions & 0 deletions
compiler/rustc_ast/src/ast.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
 pub from_glob: bool,
}

impl Delegation {
 pub fn last_segment_span(&self) -> Span {
 self.path.segments.last().unwrap().ident.span
 }
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
 List(ThinVec<(Ident, Option<Ident>)>),
Expand Down

174 changes: 96 additions & 78 deletions
compiler/rustc_ast_lowering/src/delegation.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
 AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
 ResolverAstLoweringExt,
 ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
 },
];

pub(crate) fn delegations_resolutions(
 tcx: TyCtxt<'_>,
 _: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 let krate = tcx.hir_crate(());

 let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

 // FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
 // as it is too bad to reindex whole crate on each delegation lowering.
 let ast_index = index_crate(resolver, ast_crate);

 let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

 for &def_id in &krate.delayed_ids {
 let delegation = ast_index[def_id].delegation().expect("processing delegations");
 let span = delegation.last_segment_span();

 if let Some(info) = resolver.delegation_info(def_id) {
 let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
 result.insert(def_id, res.flatten());
 } else {
 tcx.dcx().span_delayed_bug(
 span,
 format!("delegation resolution record was not found for {def_id:?}"),
 );
 }
 }

 result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();

 let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

 loop {
 visited.insert(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(info) = resolver.delegation_info(local_id)
 && let Ok(id) = info.resolution_id
 {
 def_id = id;
 if visited.contains(&def_id) {
 return Err(match visited.len() {
 1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(());
 }
 }
}

impl<'hir> LoweringContext<'_, 'hir> {
 fn is_method(&self, def_id: DefId, span: Span) -> bool {
 match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
 delegation: &Delegation,
 item_id: NodeId,
 ) -> DelegationResults<'hir> {
 let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
 let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
 let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
 self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
 self.dcx().span_delayed_bug(
 span,
 format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
 return self.generate_delegation_error(span, delegation);
 };

 match sig_id {
 Ok(sig_id) => {
 self.add_attrs_if_needed(span, sig_id);
 self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
 let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
 let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
 let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

 let (body_id, call_expr_id) = self.lower_delegation_body(
 delegation,
 is_method,
 param_count,
 &mut generics,
 span,
 );
 let (body_id, call_expr_id) =
 self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
 let decl = self.lower_delegation_decl(
 sig_id,
 param_count,
 c_variadic,
 span,
 &generics,
 delegation.id,
 call_expr_id,
 );

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
 let sig = self.lower_delegation_sig(sig_id, decl, span);
 let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
 let generics = self.arena.alloc(hir::Generics {
 has_where_clause_predicates: false,
 params: self.arena.alloc_from_iter(generics.all_params()),
 predicates: self.arena.alloc_from_iter(generics.all_predicates()),
 span,
 where_clause_span: span,
 });

 DelegationResults { body_id, sig, ident, generics }
 }
 Err(_) => self.generate_delegation_error(span, delegation),
 }
 DelegationResults { body_id, sig, ident, generics }
 }

 fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
 .collect::<Vec<_>>()
 }

 fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();
 let mut path: SmallVec<[DefId; 1]> = Default::default();

 loop {
 visited.insert(def_id);

 path.push(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(delegation_info) = self.resolver.delegation_info(local_id)
 {
 def_id = delegation_info.resolution_id;
 if visited.contains(&def_id) {
 // We encountered a cycle in the resolution, or delegation callee refers to non-existent
 // entity, in this case emit an error.
 return Err(match visited.len() {
 1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(path[0]);
 }
 }
 }

 fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
 self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
 }
Expand Down

33 changes: 24 additions & 9 deletions
compiler/rustc_ast_lowering/src/lib.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
 providers.hir_crate = lower_to_hir;
 providers.lower_delayed_owner = lower_delayed_owner;
 providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
 tcx: TyCtxt<'hir>,
 resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
 ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
 fn delegation(&self) -> Option<&ast::Delegation> {
 match self {
 AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
 _ => None,
 }
 }
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
 /// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
 })
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 // Queries that borrow `resolver_for_lowering`.
 tcx.ensure_done().output_filenames(());
 tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

 for def_id in ast_index.indices() {
 match &ast_index[def_id] {
 AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
 delayed_ids.insert(def_id);
 }
 _ => lowerer.lower_node(def_id),
 };
 if ast_index[def_id].delegation().is_some() {
 delayed_ids.insert(def_id);
 } else {
 lowerer.lower_node(def_id);
 }
 }

 // Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 let krate = tcx.hir_crate(());

 let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down

3 changes: 1 addition & 2 deletions
compiler/rustc_interface/src/passes.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 let providers = &mut Providers::default();
 providers.queries.analysis = analysis;
 providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
 providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
 // `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
 // as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
 providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
 providers.queries.early_lint_checks = early_lint_checks;
 providers.queries.env_var_os = env_var_os;
 rustc_ast_lowering::provide(&mut providers.queries);
 limits::provide(&mut providers.queries);
 proc_macro_decls::provide(&mut providers.queries);
 rustc_expand::provide(&mut providers.queries);
Expand Down

6 changes: 6 additions & 0 deletions
compiler/rustc_middle/src/queries.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
 desc { "getting delegation user-specified args" }
 }

 query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 arena_cache
 eval_always
 desc { "getting delegations resolutions" }
 }

 /// Does lifetime resolution on items. Importantly, we can't resolve
 /// lifetimes directly on things like trait methods, because of trait params.
 /// See `rustc_resolve::late::lifetimes` for details.
Expand Down

2 changes: 1 addition & 1 deletion
compiler/rustc_middle/src/ty/mod.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
 /// Refers to the next element in a delegation resolution chain.
 /// Usually points to the final resolution, as most "chains" are just
 /// one step to a trait or an impl.
 pub resolution_id: DefId,
 pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down

20 changes: 10 additions & 10 deletions
compiler/rustc_resolve/src/late.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 this.visit_path(&delegation.path);
 });

 let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
 let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
 let def_id = self
 .r
 .partial_res_map
 .get(&resolution_id)
 .get(&resolution_node_id)
 .and_then(|r| r.expect_full_res().opt_def_id());
 if let Some(resolution_id) = def_id {
 self.r
 .delegation_infos
 .insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
 } else {

 let resolution_id = def_id.ok_or_else(|| {
 self.r.tcx.dcx().span_delayed_bug(
 delegation.path.span,
 format!(
 "LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
 "LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
 ),
 );
 };
 )
 });

 let info = DelegationInfo { resolution_id };
 self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

 let Some(body) = &delegation.body else { return };
 self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
Expand Down
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rust-bors
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Jun 4, 2026

+144

−100

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delegation: split resolution and lowering
#157296
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6 changes: 6 additions & 0 deletions
compiler/rustc_ast/src/ast.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
 pub from_glob: bool,
}

impl Delegation {
 pub fn last_segment_span(&self) -> Span {
 self.path.segments.last().unwrap().ident.span
 }
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
 List(ThinVec<(Ident, Option<Ident>)>),
Expand Down

174 changes: 96 additions & 78 deletions
compiler/rustc_ast_lowering/src/delegation.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
 AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
 ResolverAstLoweringExt,
 ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
 },
];

pub(crate) fn delegations_resolutions(
 tcx: TyCtxt<'_>,
 _: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 let krate = tcx.hir_crate(());

 let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

 // FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
 // as it is too bad to reindex whole crate on each delegation lowering.
 let ast_index = index_crate(resolver, ast_crate);

 let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

 for &def_id in &krate.delayed_ids {
 let delegation = ast_index[def_id].delegation().expect("processing delegations");
 let span = delegation.last_segment_span();

 if let Some(info) = resolver.delegation_info(def_id) {
 let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
 result.insert(def_id, res.flatten());
 } else {
 tcx.dcx().span_delayed_bug(
 span,
 format!("delegation resolution record was not found for {def_id:?}"),
 );
 }
 }

 result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();

 let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

 loop {
 visited.insert(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(info) = resolver.delegation_info(local_id)
 && let Ok(id) = info.resolution_id
 {
 def_id = id;
 if visited.contains(&def_id) {
 return Err(match visited.len() {
 1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(());
 }
 }
}

impl<'hir> LoweringContext<'_, 'hir> {
 fn is_method(&self, def_id: DefId, span: Span) -> bool {
 match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
 delegation: &Delegation,
 item_id: NodeId,
 ) -> DelegationResults<'hir> {
 let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
 let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
 let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
 self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
 self.dcx().span_delayed_bug(
 span,
 format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
 return self.generate_delegation_error(span, delegation);
 };

 match sig_id {
 Ok(sig_id) => {
 self.add_attrs_if_needed(span, sig_id);
 self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
 let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
 let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
 let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

 let (body_id, call_expr_id) = self.lower_delegation_body(
 delegation,
 is_method,
 param_count,
 &mut generics,
 span,
 );
 let (body_id, call_expr_id) =
 self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
 let decl = self.lower_delegation_decl(
 sig_id,
 param_count,
 c_variadic,
 span,
 &generics,
 delegation.id,
 call_expr_id,
 );

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
 let sig = self.lower_delegation_sig(sig_id, decl, span);
 let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
 let generics = self.arena.alloc(hir::Generics {
 has_where_clause_predicates: false,
 params: self.arena.alloc_from_iter(generics.all_params()),
 predicates: self.arena.alloc_from_iter(generics.all_predicates()),
 span,
 where_clause_span: span,
 });

 DelegationResults { body_id, sig, ident, generics }
 }
 Err(_) => self.generate_delegation_error(span, delegation),
 }
 DelegationResults { body_id, sig, ident, generics }
 }

 fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
 .collect::<Vec<_>>()
 }

 fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();
 let mut path: SmallVec<[DefId; 1]> = Default::default();

 loop {
 visited.insert(def_id);

 path.push(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(delegation_info) = self.resolver.delegation_info(local_id)
 {
 def_id = delegation_info.resolution_id;
 if visited.contains(&def_id) {
 // We encountered a cycle in the resolution, or delegation callee refers to non-existent
 // entity, in this case emit an error.
 return Err(match visited.len() {
 1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(path[0]);
 }
 }
 }

 fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
 self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
 }
Expand Down

33 changes: 24 additions & 9 deletions
compiler/rustc_ast_lowering/src/lib.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
 providers.hir_crate = lower_to_hir;
 providers.lower_delayed_owner = lower_delayed_owner;
 providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
 tcx: TyCtxt<'hir>,
 resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
 ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
 fn delegation(&self) -> Option<&ast::Delegation> {
 match self {
 AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
 _ => None,
 }
 }
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
 /// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
 })
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 // Queries that borrow `resolver_for_lowering`.
 tcx.ensure_done().output_filenames(());
 tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

 for def_id in ast_index.indices() {
 match &ast_index[def_id] {
 AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
 delayed_ids.insert(def_id);
 }
 _ => lowerer.lower_node(def_id),
 };
 if ast_index[def_id].delegation().is_some() {
 delayed_ids.insert(def_id);
 } else {
 lowerer.lower_node(def_id);
 }
 }

 // Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 let krate = tcx.hir_crate(());

 let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down

3 changes: 1 addition & 2 deletions
compiler/rustc_interface/src/passes.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 let providers = &mut Providers::default();
 providers.queries.analysis = analysis;
 providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
 providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
 // `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
 // as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
 providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
 providers.queries.early_lint_checks = early_lint_checks;
 providers.queries.env_var_os = env_var_os;
 rustc_ast_lowering::provide(&mut providers.queries);
 limits::provide(&mut providers.queries);
 proc_macro_decls::provide(&mut providers.queries);
 rustc_expand::provide(&mut providers.queries);
Expand Down

6 changes: 6 additions & 0 deletions
compiler/rustc_middle/src/queries.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
 desc { "getting delegation user-specified args" }
 }

 query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 arena_cache
 eval_always
 desc { "getting delegations resolutions" }
 }

 /// Does lifetime resolution on items. Importantly, we can't resolve
 /// lifetimes directly on things like trait methods, because of trait params.
 /// See `rustc_resolve::late::lifetimes` for details.
Expand Down

2 changes: 1 addition & 1 deletion
compiler/rustc_middle/src/ty/mod.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
 /// Refers to the next element in a delegation resolution chain.
 /// Usually points to the final resolution, as most "chains" are just
 /// one step to a trait or an impl.
 pub resolution_id: DefId,
 pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down

20 changes: 10 additions & 10 deletions
compiler/rustc_resolve/src/late.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 this.visit_path(&delegation.path);
 });

 let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
 let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
 let def_id = self
 .r
 .partial_res_map
 .get(&resolution_id)
 .get(&resolution_node_id)
 .and_then(|r| r.expect_full_res().opt_def_id());
 if let Some(resolution_id) = def_id {
 self.r
 .delegation_infos
 .insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
 } else {

 let resolution_id = def_id.ok_or_else(|| {
 self.r.tcx.dcx().span_delayed_bug(
 delegation.path.span,
 format!(
 "LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
 "LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
 ),
 );
 };
 )
 });

 let info = DelegationInfo { resolution_id };
 self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

 let Some(body) = &delegation.body else { return };
 self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
Expand Down
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Jun 4, 2026

+144

−100

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delegation: split resolution and lowering
#157296
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6 changes: 6 additions & 0 deletions
compiler/rustc_ast/src/ast.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
 pub from_glob: bool,
}

impl Delegation {
 pub fn last_segment_span(&self) -> Span {
 self.path.segments.last().unwrap().ident.span
 }
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
 List(ThinVec<(Ident, Option<Ident>)>),
Expand Down

174 changes: 96 additions & 78 deletions
compiler/rustc_ast_lowering/src/delegation.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
 AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
 ResolverAstLoweringExt,
 ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
 },
];

pub(crate) fn delegations_resolutions(
 tcx: TyCtxt<'_>,
 _: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 let krate = tcx.hir_crate(());

 let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

 // FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
 // as it is too bad to reindex whole crate on each delegation lowering.
 let ast_index = index_crate(resolver, ast_crate);

 let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

 for &def_id in &krate.delayed_ids {
 let delegation = ast_index[def_id].delegation().expect("processing delegations");
 let span = delegation.last_segment_span();

 if let Some(info) = resolver.delegation_info(def_id) {
 let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
 result.insert(def_id, res.flatten());
 } else {
 tcx.dcx().span_delayed_bug(
 span,
 format!("delegation resolution record was not found for {def_id:?}"),
 );
 }
 }

 result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();

 let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

 loop {
 visited.insert(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(info) = resolver.delegation_info(local_id)
 && let Ok(id) = info.resolution_id
 {
 def_id = id;
 if visited.contains(&def_id) {
 return Err(match visited.len() {
 1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(());
 }
 }
}

impl<'hir> LoweringContext<'_, 'hir> {
 fn is_method(&self, def_id: DefId, span: Span) -> bool {
 match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
 delegation: &Delegation,
 item_id: NodeId,
 ) -> DelegationResults<'hir> {
 let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
 let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
 let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
 self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
 self.dcx().span_delayed_bug(
 span,
 format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
 return self.generate_delegation_error(span, delegation);
 };

 match sig_id {
 Ok(sig_id) => {
 self.add_attrs_if_needed(span, sig_id);
 self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
 let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
 let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
 let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

 let (body_id, call_expr_id) = self.lower_delegation_body(
 delegation,
 is_method,
 param_count,
 &mut generics,
 span,
 );
 let (body_id, call_expr_id) =
 self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
 let decl = self.lower_delegation_decl(
 sig_id,
 param_count,
 c_variadic,
 span,
 &generics,
 delegation.id,
 call_expr_id,
 );

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
 let sig = self.lower_delegation_sig(sig_id, decl, span);
 let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
 let generics = self.arena.alloc(hir::Generics {
 has_where_clause_predicates: false,
 params: self.arena.alloc_from_iter(generics.all_params()),
 predicates: self.arena.alloc_from_iter(generics.all_predicates()),
 span,
 where_clause_span: span,
 });

 DelegationResults { body_id, sig, ident, generics }
 }
 Err(_) => self.generate_delegation_error(span, delegation),
 }
 DelegationResults { body_id, sig, ident, generics }
 }

 fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
 .collect::<Vec<_>>()
 }

 fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();
 let mut path: SmallVec<[DefId; 1]> = Default::default();

 loop {
 visited.insert(def_id);

 path.push(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(delegation_info) = self.resolver.delegation_info(local_id)
 {
 def_id = delegation_info.resolution_id;
 if visited.contains(&def_id) {
 // We encountered a cycle in the resolution, or delegation callee refers to non-existent
 // entity, in this case emit an error.
 return Err(match visited.len() {
 1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(path[0]);
 }
 }
 }

 fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
 self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
 }
Expand Down

33 changes: 24 additions & 9 deletions
compiler/rustc_ast_lowering/src/lib.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
 providers.hir_crate = lower_to_hir;
 providers.lower_delayed_owner = lower_delayed_owner;
 providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
 tcx: TyCtxt<'hir>,
 resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
 ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
 fn delegation(&self) -> Option<&ast::Delegation> {
 match self {
 AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
 _ => None,
 }
 }
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
 /// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
 })
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 // Queries that borrow `resolver_for_lowering`.
 tcx.ensure_done().output_filenames(());
 tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

 for def_id in ast_index.indices() {
 match &ast_index[def_id] {
 AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
 delayed_ids.insert(def_id);
 }
 _ => lowerer.lower_node(def_id),
 };
 if ast_index[def_id].delegation().is_some() {
 delayed_ids.insert(def_id);
 } else {
 lowerer.lower_node(def_id);
 }
 }

 // Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 let krate = tcx.hir_crate(());

 let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down

3 changes: 1 addition & 2 deletions
compiler/rustc_interface/src/passes.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 let providers = &mut Providers::default();
 providers.queries.analysis = analysis;
 providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
 providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
 // `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
 // as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
 providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
 providers.queries.early_lint_checks = early_lint_checks;
 providers.queries.env_var_os = env_var_os;
 rustc_ast_lowering::provide(&mut providers.queries);
 limits::provide(&mut providers.queries);
 proc_macro_decls::provide(&mut providers.queries);
 rustc_expand::provide(&mut providers.queries);
Expand Down

6 changes: 6 additions & 0 deletions
compiler/rustc_middle/src/queries.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
 desc { "getting delegation user-specified args" }
 }

 query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 arena_cache
 eval_always
 desc { "getting delegations resolutions" }
 }

 /// Does lifetime resolution on items. Importantly, we can't resolve
 /// lifetimes directly on things like trait methods, because of trait params.
 /// See `rustc_resolve::late::lifetimes` for details.
Expand Down

2 changes: 1 addition & 1 deletion
compiler/rustc_middle/src/ty/mod.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
 /// Refers to the next element in a delegation resolution chain.
 /// Usually points to the final resolution, as most "chains" are just
 /// one step to a trait or an impl.
 pub resolution_id: DefId,
 pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down

20 changes: 10 additions & 10 deletions
compiler/rustc_resolve/src/late.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 this.visit_path(&delegation.path);
 });

 let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
 let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
 let def_id = self
 .r
 .partial_res_map
 .get(&resolution_id)
 .get(&resolution_node_id)
 .and_then(|r| r.expect_full_res().opt_def_id());
 if let Some(resolution_id) = def_id {
 self.r
 .delegation_infos
 .insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
 } else {

 let resolution_id = def_id.ok_or_else(|| {
 self.r.tcx.dcx().span_delayed_bug(
 delegation.path.span,
 format!(
 "LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
 "LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
 ),
 );
 };
 )
 });

 let info = DelegationInfo { resolution_id };
 self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

 let Some(body) = &delegation.body else { return };
 self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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delegation: split resolution and lowering#157296

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delegation: split resolution and lowering
#157296
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6 changes: 6 additions & 0 deletions
compiler/rustc_ast/src/ast.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
 pub from_glob: bool,
}

impl Delegation {
 pub fn last_segment_span(&self) -> Span {
 self.path.segments.last().unwrap().ident.span
 }
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
 List(ThinVec<(Ident, Option<Ident>)>),
Expand Down

174 changes: 96 additions & 78 deletions
compiler/rustc_ast_lowering/src/delegation.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
 AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
 ResolverAstLoweringExt,
 ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
 },
];

pub(crate) fn delegations_resolutions(
 tcx: TyCtxt<'_>,
 _: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 let krate = tcx.hir_crate(());

 let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

 // FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
 // as it is too bad to reindex whole crate on each delegation lowering.
 let ast_index = index_crate(resolver, ast_crate);

 let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

 for &def_id in &krate.delayed_ids {
 let delegation = ast_index[def_id].delegation().expect("processing delegations");
 let span = delegation.last_segment_span();

 if let Some(info) = resolver.delegation_info(def_id) {
 let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
 result.insert(def_id, res.flatten());
 } else {
 tcx.dcx().span_delayed_bug(
 span,
 format!("delegation resolution record was not found for {def_id:?}"),
 );
 }
 }

 result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();

 let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

 loop {
 visited.insert(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(info) = resolver.delegation_info(local_id)
 && let Ok(id) = info.resolution_id
 {
 def_id = id;
 if visited.contains(&def_id) {
 return Err(match visited.len() {
 1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(());
 }
 }
}

impl<'hir> LoweringContext<'_, 'hir> {
 fn is_method(&self, def_id: DefId, span: Span) -> bool {
 match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
 delegation: &Delegation,
 item_id: NodeId,
 ) -> DelegationResults<'hir> {
 let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
 let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
 let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
 self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
 self.dcx().span_delayed_bug(
 span,
 format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
 return self.generate_delegation_error(span, delegation);
 };

 match sig_id {
 Ok(sig_id) => {
 self.add_attrs_if_needed(span, sig_id);
 self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
 let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
 let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
 let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

 let (body_id, call_expr_id) = self.lower_delegation_body(
 delegation,
 is_method,
 param_count,
 &mut generics,
 span,
 );
 let (body_id, call_expr_id) =
 self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
 let decl = self.lower_delegation_decl(
 sig_id,
 param_count,
 c_variadic,
 span,
 &generics,
 delegation.id,
 call_expr_id,
 );

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
 let sig = self.lower_delegation_sig(sig_id, decl, span);
 let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
 let generics = self.arena.alloc(hir::Generics {
 has_where_clause_predicates: false,
 params: self.arena.alloc_from_iter(generics.all_params()),
 predicates: self.arena.alloc_from_iter(generics.all_predicates()),
 span,
 where_clause_span: span,
 });

 DelegationResults { body_id, sig, ident, generics }
 }
 Err(_) => self.generate_delegation_error(span, delegation),
 }
 DelegationResults { body_id, sig, ident, generics }
 }

 fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
 .collect::<Vec<_>>()
 }

 fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();
 let mut path: SmallVec<[DefId; 1]> = Default::default();

 loop {
 visited.insert(def_id);

 path.push(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(delegation_info) = self.resolver.delegation_info(local_id)
 {
 def_id = delegation_info.resolution_id;
 if visited.contains(&def_id) {
 // We encountered a cycle in the resolution, or delegation callee refers to non-existent
 // entity, in this case emit an error.
 return Err(match visited.len() {
 1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(path[0]);
 }
 }
 }

 fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
 self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
 }
Expand Down

33 changes: 24 additions & 9 deletions
compiler/rustc_ast_lowering/src/lib.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
 providers.hir_crate = lower_to_hir;
 providers.lower_delayed_owner = lower_delayed_owner;
 providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
 tcx: TyCtxt<'hir>,
 resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
 ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
 fn delegation(&self) -> Option<&ast::Delegation> {
 match self {
 AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
 _ => None,
 }
 }
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
 /// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
 })
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 // Queries that borrow `resolver_for_lowering`.
 tcx.ensure_done().output_filenames(());
 tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

 for def_id in ast_index.indices() {
 match &ast_index[def_id] {
 AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
 delayed_ids.insert(def_id);
 }
 _ => lowerer.lower_node(def_id),
 };
 if ast_index[def_id].delegation().is_some() {
 delayed_ids.insert(def_id);
 } else {
 lowerer.lower_node(def_id);
 }
 }

 // Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 let krate = tcx.hir_crate(());

 let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down

3 changes: 1 addition & 2 deletions
compiler/rustc_interface/src/passes.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 let providers = &mut Providers::default();
 providers.queries.analysis = analysis;
 providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
 providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
 // `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
 // as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
 providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
 providers.queries.early_lint_checks = early_lint_checks;
 providers.queries.env_var_os = env_var_os;
 rustc_ast_lowering::provide(&mut providers.queries);
 limits::provide(&mut providers.queries);
 proc_macro_decls::provide(&mut providers.queries);
 rustc_expand::provide(&mut providers.queries);
Expand Down

6 changes: 6 additions & 0 deletions
compiler/rustc_middle/src/queries.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
 desc { "getting delegation user-specified args" }
 }

 query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 arena_cache
 eval_always
 desc { "getting delegations resolutions" }
 }

 /// Does lifetime resolution on items. Importantly, we can't resolve
 /// lifetimes directly on things like trait methods, because of trait params.
 /// See `rustc_resolve::late::lifetimes` for details.
Expand Down

2 changes: 1 addition & 1 deletion
compiler/rustc_middle/src/ty/mod.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
 /// Refers to the next element in a delegation resolution chain.
 /// Usually points to the final resolution, as most "chains" are just
 /// one step to a trait or an impl.
 pub resolution_id: DefId,
 pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down

20 changes: 10 additions & 10 deletions
compiler/rustc_resolve/src/late.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 this.visit_path(&delegation.path);
 });

 let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
 let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
 let def_id = self
 .r
 .partial_res_map
 .get(&resolution_id)
 .get(&resolution_node_id)
 .and_then(|r| r.expect_full_res().opt_def_id());
 if let Some(resolution_id) = def_id {
 self.r
 .delegation_infos
 .insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
 } else {

 let resolution_id = def_id.ok_or_else(|| {
 self.r.tcx.dcx().span_delayed_bug(
 delegation.path.span,
 format!(
 "LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
 "LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
 ),
 );
 };
 )
 });

 let info = DelegationInfo { resolution_id };
 self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

 let Some(body) = &delegation.body else { return };
 self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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delegation: split resolution and lowering#157296

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 Merged

rust-bors
merged 1 commit into

from

Jun 4, 2026

+144

−100

 Merged


delegation: split resolution and lowering
#157296
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6 changes: 6 additions & 0 deletions
compiler/rustc_ast/src/ast.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
 pub from_glob: bool,
}

impl Delegation {
 pub fn last_segment_span(&self) -> Span {
 self.path.segments.last().unwrap().ident.span
 }
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
 List(ThinVec<(Ident, Option<Ident>)>),
Expand Down

174 changes: 96 additions & 78 deletions
compiler/rustc_ast_lowering/src/delegation.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
 AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
 ResolverAstLoweringExt,
 ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
 },
];

pub(crate) fn delegations_resolutions(
 tcx: TyCtxt<'_>,
 _: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 let krate = tcx.hir_crate(());

 let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

 // FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
 // as it is too bad to reindex whole crate on each delegation lowering.
 let ast_index = index_crate(resolver, ast_crate);

 let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

 for &def_id in &krate.delayed_ids {
 let delegation = ast_index[def_id].delegation().expect("processing delegations");
 let span = delegation.last_segment_span();

 if let Some(info) = resolver.delegation_info(def_id) {
 let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
 result.insert(def_id, res.flatten());
 } else {
 tcx.dcx().span_delayed_bug(
 span,
 format!("delegation resolution record was not found for {def_id:?}"),
 );
 }
 }

 result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();

 let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

 loop {
 visited.insert(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(info) = resolver.delegation_info(local_id)
 && let Ok(id) = info.resolution_id
 {
 def_id = id;
 if visited.contains(&def_id) {
 return Err(match visited.len() {
 1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(());
 }
 }
}

impl<'hir> LoweringContext<'_, 'hir> {
 fn is_method(&self, def_id: DefId, span: Span) -> bool {
 match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
 delegation: &Delegation,
 item_id: NodeId,
 ) -> DelegationResults<'hir> {
 let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
 let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
 let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
 self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
 self.dcx().span_delayed_bug(
 span,
 format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
 return self.generate_delegation_error(span, delegation);
 };

 match sig_id {
 Ok(sig_id) => {
 self.add_attrs_if_needed(span, sig_id);
 self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
 let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
 let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
 let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

 let (body_id, call_expr_id) = self.lower_delegation_body(
 delegation,
 is_method,
 param_count,
 &mut generics,
 span,
 );
 let (body_id, call_expr_id) =
 self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
 let decl = self.lower_delegation_decl(
 sig_id,
 param_count,
 c_variadic,
 span,
 &generics,
 delegation.id,
 call_expr_id,
 );

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
 let sig = self.lower_delegation_sig(sig_id, decl, span);
 let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
 let generics = self.arena.alloc(hir::Generics {
 has_where_clause_predicates: false,
 params: self.arena.alloc_from_iter(generics.all_params()),
 predicates: self.arena.alloc_from_iter(generics.all_predicates()),
 span,
 where_clause_span: span,
 });

 DelegationResults { body_id, sig, ident, generics }
 }
 Err(_) => self.generate_delegation_error(span, delegation),
 }
 DelegationResults { body_id, sig, ident, generics }
 }

 fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
 .collect::<Vec<_>>()
 }

 fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();
 let mut path: SmallVec<[DefId; 1]> = Default::default();

 loop {
 visited.insert(def_id);

 path.push(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(delegation_info) = self.resolver.delegation_info(local_id)
 {
 def_id = delegation_info.resolution_id;
 if visited.contains(&def_id) {
 // We encountered a cycle in the resolution, or delegation callee refers to non-existent
 // entity, in this case emit an error.
 return Err(match visited.len() {
 1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(path[0]);
 }
 }
 }

 fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
 self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
 }
Expand Down

33 changes: 24 additions & 9 deletions
compiler/rustc_ast_lowering/src/lib.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
 providers.hir_crate = lower_to_hir;
 providers.lower_delayed_owner = lower_delayed_owner;
 providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
 tcx: TyCtxt<'hir>,
 resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
 ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
 fn delegation(&self) -> Option<&ast::Delegation> {
 match self {
 AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
 _ => None,
 }
 }
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
 /// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
 })
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 // Queries that borrow `resolver_for_lowering`.
 tcx.ensure_done().output_filenames(());
 tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

 for def_id in ast_index.indices() {
 match &ast_index[def_id] {
 AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
 delayed_ids.insert(def_id);
 }
 _ => lowerer.lower_node(def_id),
 };
 if ast_index[def_id].delegation().is_some() {
 delayed_ids.insert(def_id);
 } else {
 lowerer.lower_node(def_id);
 }
 }

 // Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 let krate = tcx.hir_crate(());

 let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down

3 changes: 1 addition & 2 deletions
compiler/rustc_interface/src/passes.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 let providers = &mut Providers::default();
 providers.queries.analysis = analysis;
 providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
 providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
 // `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
 // as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
 providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
 providers.queries.early_lint_checks = early_lint_checks;
 providers.queries.env_var_os = env_var_os;
 rustc_ast_lowering::provide(&mut providers.queries);
 limits::provide(&mut providers.queries);
 proc_macro_decls::provide(&mut providers.queries);
 rustc_expand::provide(&mut providers.queries);
Expand Down

6 changes: 6 additions & 0 deletions
compiler/rustc_middle/src/queries.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
 desc { "getting delegation user-specified args" }
 }

 query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 arena_cache
 eval_always
 desc { "getting delegations resolutions" }
 }

 /// Does lifetime resolution on items. Importantly, we can't resolve
 /// lifetimes directly on things like trait methods, because of trait params.
 /// See `rustc_resolve::late::lifetimes` for details.
Expand Down

2 changes: 1 addition & 1 deletion
compiler/rustc_middle/src/ty/mod.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
 /// Refers to the next element in a delegation resolution chain.
 /// Usually points to the final resolution, as most "chains" are just
 /// one step to a trait or an impl.
 pub resolution_id: DefId,
 pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down

20 changes: 10 additions & 10 deletions
compiler/rustc_resolve/src/late.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 this.visit_path(&delegation.path);
 });

 let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
 let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
 let def_id = self
 .r
 .partial_res_map
 .get(&resolution_id)
 .get(&resolution_node_id)
 .and_then(|r| r.expect_full_res().opt_def_id());
 if let Some(resolution_id) = def_id {
 self.r
 .delegation_infos
 .insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
 } else {

 let resolution_id = def_id.ok_or_else(|| {
 self.r.tcx.dcx().span_delayed_bug(
 delegation.path.span,
 format!(
 "LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
 "LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
 ),
 );
 };
 )
 });

 let info = DelegationInfo { resolution_id };
 self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

 let Some(body) = &delegation.body else { return };
 self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
Expand Down
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if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
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}
});
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unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
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})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Jun 4, 2026

+144

−100

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delegation: split resolution and lowering
#157296
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6 changes: 6 additions & 0 deletions
compiler/rustc_ast/src/ast.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
 pub from_glob: bool,
}

impl Delegation {
 pub fn last_segment_span(&self) -> Span {
 self.path.segments.last().unwrap().ident.span
 }
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
 List(ThinVec<(Ident, Option<Ident>)>),
Expand Down

174 changes: 96 additions & 78 deletions
compiler/rustc_ast_lowering/src/delegation.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
 AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
 ResolverAstLoweringExt,
 ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
 },
];

pub(crate) fn delegations_resolutions(
 tcx: TyCtxt<'_>,
 _: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 let krate = tcx.hir_crate(());

 let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

 // FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
 // as it is too bad to reindex whole crate on each delegation lowering.
 let ast_index = index_crate(resolver, ast_crate);

 let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

 for &def_id in &krate.delayed_ids {
 let delegation = ast_index[def_id].delegation().expect("processing delegations");
 let span = delegation.last_segment_span();

 if let Some(info) = resolver.delegation_info(def_id) {
 let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
 result.insert(def_id, res.flatten());
 } else {
 tcx.dcx().span_delayed_bug(
 span,
 format!("delegation resolution record was not found for {def_id:?}"),
 );
 }
 }

 result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();

 let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

 loop {
 visited.insert(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(info) = resolver.delegation_info(local_id)
 && let Ok(id) = info.resolution_id
 {
 def_id = id;
 if visited.contains(&def_id) {
 return Err(match visited.len() {
 1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(());
 }
 }
}

impl<'hir> LoweringContext<'_, 'hir> {
 fn is_method(&self, def_id: DefId, span: Span) -> bool {
 match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
 delegation: &Delegation,
 item_id: NodeId,
 ) -> DelegationResults<'hir> {
 let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
 let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
 let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
 self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
 self.dcx().span_delayed_bug(
 span,
 format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
 return self.generate_delegation_error(span, delegation);
 };

 match sig_id {
 Ok(sig_id) => {
 self.add_attrs_if_needed(span, sig_id);
 self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
 let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
 let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
 let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

 let (body_id, call_expr_id) = self.lower_delegation_body(
 delegation,
 is_method,
 param_count,
 &mut generics,
 span,
 );
 let (body_id, call_expr_id) =
 self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
 let decl = self.lower_delegation_decl(
 sig_id,
 param_count,
 c_variadic,
 span,
 &generics,
 delegation.id,
 call_expr_id,
 );

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
 let sig = self.lower_delegation_sig(sig_id, decl, span);
 let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
 let generics = self.arena.alloc(hir::Generics {
 has_where_clause_predicates: false,
 params: self.arena.alloc_from_iter(generics.all_params()),
 predicates: self.arena.alloc_from_iter(generics.all_predicates()),
 span,
 where_clause_span: span,
 });

 DelegationResults { body_id, sig, ident, generics }
 }
 Err(_) => self.generate_delegation_error(span, delegation),
 }
 DelegationResults { body_id, sig, ident, generics }
 }

 fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
 .collect::<Vec<_>>()
 }

 fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();
 let mut path: SmallVec<[DefId; 1]> = Default::default();

 loop {
 visited.insert(def_id);

 path.push(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(delegation_info) = self.resolver.delegation_info(local_id)
 {
 def_id = delegation_info.resolution_id;
 if visited.contains(&def_id) {
 // We encountered a cycle in the resolution, or delegation callee refers to non-existent
 // entity, in this case emit an error.
 return Err(match visited.len() {
 1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(path[0]);
 }
 }
 }

 fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
 self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
 }
Expand Down

33 changes: 24 additions & 9 deletions
compiler/rustc_ast_lowering/src/lib.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
 providers.hir_crate = lower_to_hir;
 providers.lower_delayed_owner = lower_delayed_owner;
 providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
 tcx: TyCtxt<'hir>,
 resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
 ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
 fn delegation(&self) -> Option<&ast::Delegation> {
 match self {
 AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
 _ => None,
 }
 }
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
 /// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
 })
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 // Queries that borrow `resolver_for_lowering`.
 tcx.ensure_done().output_filenames(());
 tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

 for def_id in ast_index.indices() {
 match &ast_index[def_id] {
 AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
 delayed_ids.insert(def_id);
 }
 _ => lowerer.lower_node(def_id),
 };
 if ast_index[def_id].delegation().is_some() {
 delayed_ids.insert(def_id);
 } else {
 lowerer.lower_node(def_id);
 }
 }

 // Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 let krate = tcx.hir_crate(());

 let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down

3 changes: 1 addition & 2 deletions
compiler/rustc_interface/src/passes.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 let providers = &mut Providers::default();
 providers.queries.analysis = analysis;
 providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
 providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
 // `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
 // as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
 providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
 providers.queries.early_lint_checks = early_lint_checks;
 providers.queries.env_var_os = env_var_os;
 rustc_ast_lowering::provide(&mut providers.queries);
 limits::provide(&mut providers.queries);
 proc_macro_decls::provide(&mut providers.queries);
 rustc_expand::provide(&mut providers.queries);
Expand Down

6 changes: 6 additions & 0 deletions
compiler/rustc_middle/src/queries.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
 desc { "getting delegation user-specified args" }
 }

 query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 arena_cache
 eval_always
 desc { "getting delegations resolutions" }
 }

 /// Does lifetime resolution on items. Importantly, we can't resolve
 /// lifetimes directly on things like trait methods, because of trait params.
 /// See `rustc_resolve::late::lifetimes` for details.
Expand Down

2 changes: 1 addition & 1 deletion
compiler/rustc_middle/src/ty/mod.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
 /// Refers to the next element in a delegation resolution chain.
 /// Usually points to the final resolution, as most "chains" are just
 /// one step to a trait or an impl.
 pub resolution_id: DefId,
 pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down

20 changes: 10 additions & 10 deletions
compiler/rustc_resolve/src/late.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 this.visit_path(&delegation.path);
 });

 let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
 let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
 let def_id = self
 .r
 .partial_res_map
 .get(&resolution_id)
 .get(&resolution_node_id)
 .and_then(|r| r.expect_full_res().opt_def_id());
 if let Some(resolution_id) = def_id {
 self.r
 .delegation_infos
 .insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
 } else {

 let resolution_id = def_id.ok_or_else(|| {
 self.r.tcx.dcx().span_delayed_bug(
 delegation.path.span,
 format!(
 "LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
 "LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
 ),
 );
 };
 )
 });

 let info = DelegationInfo { resolution_id };
 self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

 let Some(body) = &delegation.body else { return };
 self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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Jun 4, 2026

+144

−100

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delegation: split resolution and lowering
#157296
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6 changes: 6 additions & 0 deletions
compiler/rustc_ast/src/ast.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3921,6 +3921,12 @@ pub struct Delegation {
 pub from_glob: bool,
}

impl Delegation {
 pub fn last_segment_span(&self) -> Span {
 self.path.segments.last().unwrap().ident.span
 }
}

#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
pub enum DelegationSuffixes {
 List(ThinVec<(Ident, Option<Ident>)>),
Expand Down

174 changes: 96 additions & 78 deletions
compiler/rustc_ast_lowering/src/delegation.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -44,22 +44,20 @@ use hir::{BodyId, HirId};
use rustc_abi::ExternAbi;
use rustc_ast as ast;
use rustc_ast::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::ErrorGuaranteed;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::attrs::{AttributeKind, InlineAttr};
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, FnDeclFlags};
use rustc_middle::span_bug;
use rustc_middle::ty::Asyncness;
use rustc_middle::ty::{Asyncness, TyCtxt};
use rustc_span::symbol::kw;
use rustc_span::{Ident, Span, Symbol};
use smallvec::SmallVec;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};

use crate::delegation::generics::{GenericsGenerationResult, GenericsGenerationResults};
use crate::errors::{CycleInDelegationSignatureResolution, UnresolvedDelegationCallee};
use crate::{
 AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
 ResolverAstLoweringExt,
 ResolverAstLoweringExt, index_crate,
};

mod generics;
Expand DownExpand Up@@ -105,6 +103,66 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
 },
];

pub(crate) fn delegations_resolutions(
 tcx: TyCtxt<'_>,
 _: (),
) -> FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 let krate = tcx.hir_crate(());

 let (resolver, ast_crate) = &*krate.delayed_resolver.borrow();

 // FIXME!!!(fn_delegation): make ast index lifetime same as resolver,
 // as it is too bad to reindex whole crate on each delegation lowering.
 let ast_index = index_crate(resolver, ast_crate);

 let mut result = FxIndexMap::<LocalDefId, Result<DefId, ErrorGuaranteed>>::default();

 for &def_id in &krate.delayed_ids {
 let delegation = ast_index[def_id].delegation().expect("processing delegations");
 let span = delegation.last_segment_span();

 if let Some(info) = resolver.delegation_info(def_id) {
 let res = info.resolution_id.map(|id| check_for_cycles(tcx, id, span).map(|_| id));
 result.insert(def_id, res.flatten());
 } else {
 tcx.dcx().span_delayed_bug(
 span,
 format!("delegation resolution record was not found for {def_id:?}"),
 );
 }
 }

 result
}

fn check_for_cycles(tcx: TyCtxt<'_>, mut def_id: DefId, span: Span) -> Result<(), ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();

 let (resolver, _) = &*tcx.hir_crate(()).delayed_resolver.borrow();

 loop {
 visited.insert(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(info) = resolver.delegation_info(local_id)
 && let Ok(id) = info.resolution_id
 {
 def_id = id;
 if visited.contains(&def_id) {
 return Err(match visited.len() {
 1 => tcx.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => tcx.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(());
 }
 }
}

impl<'hir> LoweringContext<'_, 'hir> {
 fn is_method(&self, def_id: DefId, span: Span) -> bool {
 match self.tcx.def_kind(def_id) {
Expand All@@ -119,13 +177,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
 delegation: &Delegation,
 item_id: NodeId,
 ) -> DelegationResults<'hir> {
 let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
 let span = self.lower_span(delegation.last_segment_span());

// Delegation can be unresolved in illegal places such as function bodies in extern blocks (see #151356)
 let sig_id = if let Some(delegation_info) = self.resolver.delegation_info(self.owner.def_id)
{
 self.get_sig_id(delegation_info.resolution_id, span)
} else {
let sig_id = self.tcx.delegations_resolutions(()).get(&self.owner.def_id).copied();

// Delegation can be missing from the `delegations_resolutions` table
// in illegal places such as function bodies in extern blocks (see #151356).
let Some(Ok(sig_id)) = sig_id else {
 self.dcx().span_delayed_bug(
 span,
 format!("LoweringContext: the delegation {:?} is unresolved", item_id),
Expand All@@ -134,49 +192,39 @@ impl<'hir> LoweringContext<'_, 'hir> {
 return self.generate_delegation_error(span, delegation);
 };

 match sig_id {
 Ok(sig_id) => {
 self.add_attrs_if_needed(span, sig_id);
 self.add_attrs_if_needed(span, sig_id);

let is_method = self.is_method(sig_id, span);
 let is_method = self.is_method(sig_id, span);

let (param_count, c_variadic) = self.param_count(sig_id);
 let (param_count, c_variadic) = self.param_count(sig_id);

let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);
 let mut generics = self.uplift_delegation_generics(delegation, sig_id, is_method);

 let (body_id, call_expr_id) = self.lower_delegation_body(
 delegation,
 is_method,
 param_count,
 &mut generics,
 span,
 );
 let (body_id, call_expr_id) =
 self.lower_delegation_body(delegation, is_method, param_count, &mut generics, span);

let decl = self.lower_delegation_decl(
sig_id,
param_count,
c_variadic,
span,
&generics,
delegation.id,
call_expr_id,
);
 let decl = self.lower_delegation_decl(
 sig_id,
 param_count,
 c_variadic,
 span,
 &generics,
 delegation.id,
 call_expr_id,
 );

let sig = self.lower_delegation_sig(sig_id, decl, span);
let ident = self.lower_ident(delegation.ident);
 let sig = self.lower_delegation_sig(sig_id, decl, span);
 let ident = self.lower_ident(delegation.ident);

let generics = self.arena.alloc(hir::Generics {
has_where_clause_predicates: false,
params: self.arena.alloc_from_iter(generics.all_params()),
predicates: self.arena.alloc_from_iter(generics.all_predicates()),
span,
where_clause_span: span,
});
 let generics = self.arena.alloc(hir::Generics {
 has_where_clause_predicates: false,
 params: self.arena.alloc_from_iter(generics.all_params()),
 predicates: self.arena.alloc_from_iter(generics.all_predicates()),
 span,
 where_clause_span: span,
 });

 DelegationResults { body_id, sig, ident, generics }
 }
 Err(_) => self.generate_delegation_error(span, delegation),
 }
 DelegationResults { body_id, sig, ident, generics }
 }

 fn add_attrs_if_needed(&mut self, span: Span, sig_id: DefId) {
Expand DownExpand Up@@ -230,36 +278,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
 .collect::<Vec<_>>()
 }

 fn get_sig_id(&self, mut def_id: DefId, span: Span) -> Result<DefId, ErrorGuaranteed> {
 let mut visited: FxHashSet<DefId> = Default::default();
 let mut path: SmallVec<[DefId; 1]> = Default::default();

 loop {
 visited.insert(def_id);

 path.push(def_id);

 // If def_id is in local crate and it corresponds to another delegation
 // it means that we refer to another delegation as a callee, so in order to obtain
 // a signature DefId we obtain NodeId of the callee delegation and try to get signature from it.
 if let Some(local_id) = def_id.as_local()
 && let Some(delegation_info) = self.resolver.delegation_info(local_id)
 {
 def_id = delegation_info.resolution_id;
 if visited.contains(&def_id) {
 // We encountered a cycle in the resolution, or delegation callee refers to non-existent
 // entity, in this case emit an error.
 return Err(match visited.len() {
 1 => self.dcx().emit_err(UnresolvedDelegationCallee { span }),
 _ => self.dcx().emit_err(CycleInDelegationSignatureResolution { span }),
 });
 }
 } else {
 return Ok(path[0]);
 }
 }
 }

 fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
 self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
 }
Expand Down

33 changes: 24 additions & 9 deletions
compiler/rustc_ast_lowering/src/lib.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -60,6 +60,7 @@ use rustc_hir::{
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
use rustc_middle::hir::{self as mid_hir};
use rustc_middle::queries::Providers;
use rustc_middle::span_bug;
use rustc_middle::ty::{DelegationInfo, PerOwnerResolverData, ResolverAstLowering, TyCtxt};
use rustc_session::errors::add_feature_diagnostics;
Expand DownExpand Up@@ -91,6 +92,12 @@ mod pat;
mod path;
pub mod stability;

pub fn provide(providers: &mut Providers) {
 providers.hir_crate = lower_to_hir;
 providers.lower_delayed_owner = lower_delayed_owner;
 providers.delegations_resolutions = delegation::delegations_resolutions;
}

struct LoweringContext<'a, 'hir> {
 tcx: TyCtxt<'hir>,
 resolver: &'a ResolverAstLowering<'hir>,
Expand DownExpand Up@@ -433,6 +440,16 @@ enum AstOwner<'a> {
 ForeignItem(&'a ast::ForeignItem),
}

impl AstOwner<'_> {
 fn delegation(&self) -> Option<&ast::Delegation> {
 match self {
 AstOwner::Item(Item { kind: ItemKind::Delegation(d), .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation(d), .. }, _) => Some(d),
 _ => None,
 }
 }
}

#[derive(Copy, Clone, Debug)]
enum TryBlockScope {
 /// There isn't a `try` block, so a `?` will use `return`.
Expand DownExpand Up@@ -512,7 +529,7 @@ fn compute_hir_hash(
 })
}

pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 // Queries that borrow `resolver_for_lowering`.
 tcx.ensure_done().output_filenames(());
 tcx.ensure_done().early_lint_checks(());
Expand All@@ -536,13 +553,11 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
 let mut delayed_ids: FxIndexSet<LocalDefId> = Default::default();

 for def_id in ast_index.indices() {
 match &ast_index[def_id] {
 AstOwner::Item(Item { kind: ItemKind::Delegation { .. }, .. })
 | AstOwner::AssocItem(Item { kind: AssocItemKind::Delegation { .. }, .. }, _) => {
 delayed_ids.insert(def_id);
 }
 _ => lowerer.lower_node(def_id),
 };
 if ast_index[def_id].delegation().is_some() {
 delayed_ids.insert(def_id);
 } else {
 lowerer.lower_node(def_id);
 }
 }

 // Don't hash unless necessary, because it's expensive.
Expand All@@ -554,7 +569,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> mid_hir::Crate<'_> {
}

/// Lowers an AST owner corresponding to `def_id`, now only delegations are lowered this way.
pub fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
fn lower_delayed_owner(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 let krate = tcx.hir_crate(());

 let (resolver, krate) = &*krate.delayed_resolver.borrow();
Expand Down

3 changes: 1 addition & 2 deletions
compiler/rustc_interface/src/passes.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -877,8 +877,6 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 let providers = &mut Providers::default();
 providers.queries.analysis = analysis;
 providers.queries.hir_crate = rustc_ast_lowering::lower_to_hir;
 providers.queries.lower_delayed_owner = rustc_ast_lowering::lower_delayed_owner;
 // `hir_delayed_owner` is fed during `lower_delayed_owner`, by default it returns phantom,
 // as if this query was not fed it means that `MaybeOwner` does not exist for provided LocalDefId.
 providers.queries.hir_delayed_owner = |_, _| MaybeOwner::Phantom;
Expand All@@ -887,6 +885,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
 providers.queries.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
 providers.queries.early_lint_checks = early_lint_checks;
 providers.queries.env_var_os = env_var_os;
 rustc_ast_lowering::provide(&mut providers.queries);
 limits::provide(&mut providers.queries);
 proc_macro_decls::provide(&mut providers.queries);
 rustc_expand::provide(&mut providers.queries);
Expand Down

6 changes: 6 additions & 0 deletions
compiler/rustc_middle/src/queries.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -2069,6 +2069,12 @@ rustc_queries! {
 desc { "getting delegation user-specified args" }
 }

 query delegations_resolutions(_: ()) -> &'tcx FxIndexMap<LocalDefId, Result<DefId, ErrorGuaranteed>> {
 arena_cache
 eval_always
 desc { "getting delegations resolutions" }
 }

 /// Does lifetime resolution on items. Importantly, we can't resolve
 /// lifetimes directly on things like trait methods, because of trait params.
 /// See `rustc_resolve::late::lifetimes` for details.
Expand Down

2 changes: 1 addition & 1 deletion
compiler/rustc_middle/src/ty/mod.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -270,7 +270,7 @@ pub struct DelegationInfo {
 /// Refers to the next element in a delegation resolution chain.
 /// Usually points to the final resolution, as most "chains" are just
 /// one step to a trait or an impl.
 pub resolution_id: DefId,
 pub resolution_id: Result<DefId, ErrorGuaranteed>,
}

#[derive(Clone, Copy, Debug, StableHash)]
Expand Down

20 changes: 10 additions & 10 deletions
compiler/rustc_resolve/src/late.rs

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Expand Up@@ -3899,24 +3899,24 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 this.visit_path(&delegation.path);
 });

 let resolution_id = if is_in_trait_impl { item_id } else { delegation.id };
 let resolution_node_id = if is_in_trait_impl { item_id } else { delegation.id };
 let def_id = self
 .r
 .partial_res_map
 .get(&resolution_id)
 .get(&resolution_node_id)
 .and_then(|r| r.expect_full_res().opt_def_id());
 if let Some(resolution_id) = def_id {
 self.r
 .delegation_infos
 .insert(self.r.current_owner.def_id, DelegationInfo { resolution_id });
 } else {

 let resolution_id = def_id.ok_or_else(|| {
 self.r.tcx.dcx().span_delayed_bug(
 delegation.path.span,
 format!(
 "LoweringContext: couldn't resolve node {resolution_id:?} in delegation item",
 "LateResolutionVisitor: couldn't resolve node {resolution_node_id:?} in delegation item",
 ),
 );
 };
 )
 });

 let info = DelegationInfo { resolution_id };
 self.r.delegation_infos.insert(self.r.current_owner.def_id, info);

 let Some(body) = &delegation.body else { return };
 self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
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