From cf4d480eff238667a779c56938ebc51956f586d4 Mon Sep 17 00:00:00 2001
From: Jonathan Brouwer <jonathantbrouwer@gmail.com>
Date: Mon, 12 Jan 2026 19:43:31 +0100
Subject: [PATCH] Port `#[rustc_dump_def_parents]`

---
 compiler/rustc_attr_parsing/src/attributes/rustc_dump.rs | 9 +++++++++
 compiler/rustc_attr_parsing/src/context.rs               | 3 ++-
 compiler/rustc_hir/src/attrs/data_structures.rs          | 3 +++
 compiler/rustc_hir/src/attrs/encode_cross_crate.rs       | 1 +
 compiler/rustc_hir_analysis/src/collect/dump.rs          | 5 +++--
 compiler/rustc_passes/src/check_attr.rs                  | 2 +-
 6 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_attr_parsing/src/attributes/rustc_dump.rs b/compiler/rustc_attr_parsing/src/attributes/rustc_dump.rs
index d5593a7e02f3..86cc88fe26e6 100644
--- a/compiler/rustc_attr_parsing/src/attributes/rustc_dump.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/rustc_dump.rs
@@ -15,3 +15,12 @@ impl<S: Stage> NoArgsAttributeParser<S> for RustcDumpUserArgs {
     const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Fn)]);
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcDumpUserArgs;
 }
+
+pub(crate) struct RustcDumpDefParents;
+
+impl<S: Stage> NoArgsAttributeParser<S> for RustcDumpDefParents {
+    const PATH: &[Symbol] = &[sym::rustc_dump_def_parents];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Fn)]);
+    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcDumpDefParents;
+}
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
index 4ba1936086a2..adcdbf7752a3 100644
--- a/compiler/rustc_attr_parsing/src/context.rs
+++ b/compiler/rustc_attr_parsing/src/context.rs
@@ -63,7 +63,7 @@ use crate::attributes::proc_macro_attrs::{
 };
 use crate::attributes::prototype::CustomMirParser;
 use crate::attributes::repr::{AlignParser, AlignStaticParser, ReprParser};
-use crate::attributes::rustc_dump::RustcDumpUserArgs;
+use crate::attributes::rustc_dump::{RustcDumpUserArgs, RustcDumpDefParents};
 use crate::attributes::rustc_internal::{
     RustcHasIncoherentInherentImplsParser, RustcLayoutScalarValidRangeEndParser,
     RustcLayoutScalarValidRangeStartParser, RustcLegacyConstGenericsParser,
@@ -268,6 +268,7 @@ attribute_parsers!(
         Single<WithoutArgs<ProcMacroParser>>,
         Single<WithoutArgs<PubTransparentParser>>,
         Single<WithoutArgs<RustcCoherenceIsCoreParser>>,
+        Single<WithoutArgs<RustcDumpDefParents >>,
         Single<WithoutArgs<RustcDumpUserArgs>>,
         Single<WithoutArgs<RustcHasIncoherentInherentImplsParser>>,
         Single<WithoutArgs<RustcLintDiagnosticsParser>>,
diff --git a/compiler/rustc_hir/src/attrs/data_structures.rs b/compiler/rustc_hir/src/attrs/data_structures.rs
index 42575f712d4a..63a89c84ed4a 100644
--- a/compiler/rustc_hir/src/attrs/data_structures.rs
+++ b/compiler/rustc_hir/src/attrs/data_structures.rs
@@ -906,6 +906,9 @@ pub enum AttributeKind {
     /// Represents `#[rustc_coherence_is_core]`
     RustcCoherenceIsCore(Span),
 
+    /// Represents `#[rustc_dump_def_parents]`
+    RustcDumpDefParents,
+    
     /// Represents `#[rustc_dump_user_args]`
     RustcDumpUserArgs,
 
diff --git a/compiler/rustc_hir/src/attrs/encode_cross_crate.rs b/compiler/rustc_hir/src/attrs/encode_cross_crate.rs
index 07dd9f8e3e06..aa2a7cb6d4b4 100644
--- a/compiler/rustc_hir/src/attrs/encode_cross_crate.rs
+++ b/compiler/rustc_hir/src/attrs/encode_cross_crate.rs
@@ -97,6 +97,7 @@ impl AttributeKind {
             Repr { .. } => No,
             RustcBuiltinMacro { .. } => Yes,
             RustcCoherenceIsCore(..) => No,
+            RustcDumpDefParents => No,
             RustcDumpUserArgs => No,
             RustcHasIncoherentInherentImpls => Yes,
             RustcLayoutScalarValidRangeEnd(..) => Yes,
diff --git a/compiler/rustc_hir_analysis/src/collect/dump.rs b/compiler/rustc_hir_analysis/src/collect/dump.rs
index b167f31a246c..1ace60721eae 100644
--- a/compiler/rustc_hir_analysis/src/collect/dump.rs
+++ b/compiler/rustc_hir_analysis/src/collect/dump.rs
@@ -1,6 +1,7 @@
 use rustc_hir as hir;
 use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
-use rustc_hir::intravisit;
+use rustc_hir::{find_attr, intravisit};
+use rustc_hir::attrs::AttributeKind;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
 use rustc_span::sym;
@@ -54,7 +55,7 @@ pub(crate) fn predicates_and_item_bounds(tcx: TyCtxt<'_>) {
 pub(crate) fn def_parents(tcx: TyCtxt<'_>) {
     for iid in tcx.hir_free_items() {
         let did = iid.owner_id.def_id;
-        if tcx.has_attr(did, sym::rustc_dump_def_parents) {
+        if find_attr!(tcx.get_all_attrs(did), AttributeKind::RustcDumpDefParents) {
             struct AnonConstFinder<'tcx> {
                 tcx: TyCtxt<'tcx>,
                 anon_consts: Vec<LocalDefId>,
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index f088bd5b5119..dfa407964fc4 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -310,6 +310,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::RustcHasIncoherentInherentImpls
                     | AttributeKind::MustNotSupend { .. }
                     | AttributeKind::RustcDumpUserArgs
+                    | AttributeKind::RustcDumpDefParents
                 ) => { /* do nothing  */ }
                 Attribute::Unparsed(attr_item) => {
                     style = Some(attr_item.style);
@@ -369,7 +370,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             | sym::rustc_abi
                             | sym::rustc_layout
                             | sym::rustc_proc_macro_decls
-                            | sym::rustc_dump_def_parents
                             | sym::rustc_never_type_options
                             | sym::rustc_autodiff
                             | sym::rustc_capture_analysis