Rollup merge of #138929 - oli-obk:assoc-ctxt-of-trait, r=compiler-errors

Visitors track whether an assoc item is in a trait impl or an inherent impl

`AssocCtxt::Impl` now contains an `of_trait` field. This allows ast lowering and nameres to not have to track whether we're in a trait impl or an inherent impl.

compiler/rustc_ast/src/mut_visit.rs

@@ -1318,7 +1318,9 @@ impl WalkItemKind for ItemKind {
                 visit_polarity(vis, polarity);
                 visit_opt(of_trait, |trait_ref| vis.visit_trait_ref(trait_ref));
                 vis.visit_ty(self_ty);
-                items.flat_map_in_place(|item| vis.flat_map_assoc_item(item, AssocCtxt::Impl));
+                items.flat_map_in_place(|item| {
+                    vis.flat_map_assoc_item(item, AssocCtxt::Impl { of_trait: of_trait.is_some() })
+                });
             }
             ItemKind::Trait(box Trait { safety, is_auto: _, generics, bounds, items }) => {
                 visit_safety(vis, safety);

compiler/rustc_ast/src/visit.rs

@@ -23,7 +23,7 @@ use crate::ptr::P;
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub enum AssocCtxt {
     Trait,
-    Impl,
+    Impl { of_trait: bool },
 }
 
 #[derive(Copy, Clone, Debug, PartialEq)]
@@ -422,7 +422,12 @@ impl WalkItemKind for ItemKind {
                 try_visit!(visitor.visit_generics(generics));
                 visit_opt!(visitor, visit_trait_ref, of_trait);
                 try_visit!(visitor.visit_ty(self_ty));
-                walk_list!(visitor, visit_assoc_item, items, AssocCtxt::Impl);
+                walk_list!(
+                    visitor,
+                    visit_assoc_item,
+                    items,
+                    AssocCtxt::Impl { of_trait: of_trait.is_some() }
+                );
             }
             ItemKind::Struct(struct_definition, generics)
             | ItemKind::Union(struct_definition, generics) => {

compiler/rustc_ast_lowering/src/delegation.rs

@@ -61,8 +61,14 @@ pub(crate) struct DelegationResults<'hir> {
 
 impl<'hir> LoweringContext<'_, 'hir> {
     /// Defines whether the delegatee is an associated function whose first parameter is `self`.
-    pub(crate) fn delegatee_is_method(&self, item_id: NodeId, path_id: NodeId, span: Span) -> bool {
+    pub(crate) fn delegatee_is_method(
-        let sig_id = self.get_delegation_sig_id(item_id, path_id, span);
+        &self,
+        item_id: NodeId,
+        path_id: NodeId,
+        span: Span,
+        is_in_trait_impl: bool,
+    ) -> bool {
+        let sig_id = self.get_delegation_sig_id(item_id, path_id, span, is_in_trait_impl);
         let Ok(sig_id) = sig_id else {
             return false;
         };
@@ -88,9 +94,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
         &mut self,
         delegation: &Delegation,
         item_id: NodeId,
+        is_in_trait_impl: bool,
     ) -> DelegationResults<'hir> {
         let span = self.lower_span(delegation.path.segments.last().unwrap().ident.span);
-        let sig_id = self.get_delegation_sig_id(item_id, delegation.id, span);
+        let sig_id = self.get_delegation_sig_id(item_id, delegation.id, span, is_in_trait_impl);
         match sig_id {
             Ok(sig_id) => {
                 let (param_count, c_variadic) = self.param_count(sig_id);
@@ -110,8 +117,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
         item_id: NodeId,
         path_id: NodeId,
         span: Span,
+        is_in_trait_impl: bool,
     ) -> Result<DefId, ErrorGuaranteed> {
-        let sig_id = if self.is_in_trait_impl { item_id } else { path_id };
+        let sig_id = if is_in_trait_impl { item_id } else { path_id };
         self.get_resolution_id(sig_id, span)
     }
 

compiler/rustc_ast_lowering/src/item.rs

@@ -7,7 +7,6 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
 use rustc_hir::{self as hir, HirId, PredicateOrigin};
 use rustc_index::{IndexSlice, IndexVec};
-use rustc_middle::span_bug;
 use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
 use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::{DUMMY_SP, DesugaringKind, Ident, Span, Symbol, kw, sym};
@@ -104,10 +103,7 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
     }
 
     fn lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt) {
-        let def_id = self.resolver.node_id_to_def_id[&item.id];
+        self.with_lctx(item.id, |lctx| lctx.lower_assoc_item(item, ctxt))
-        let parent_id = self.tcx.local_parent(def_id);
-        let parent_hir = self.lower_node(parent_id).unwrap();
-        self.with_lctx(item.id, |lctx| lctx.lower_assoc_item(item, ctxt, parent_hir))
     }
 
     fn lower_foreign_item(&mut self, item: &ForeignItem) {
@@ -405,10 +401,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         (trait_ref, lowered_ty)
                     });
 
-                self.is_in_trait_impl = trait_ref.is_some();
+                let new_impl_items = self.arena.alloc_from_iter(
-                let new_impl_items = self
+                    impl_items
-                    .arena
+                        .iter()
-                    .alloc_from_iter(impl_items.iter().map(|item| self.lower_impl_item_ref(item)));
+                        .map(|item| self.lower_impl_item_ref(item, trait_ref.is_some())),
+                );
 
                 // `defaultness.has_value()` is never called for an `impl`, always `true` in order
                 // to not cause an assertion failure inside the `lower_defaultness` function.
@@ -485,7 +482,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             ItemKind::Delegation(box delegation) => {
                 debug_assert_ne!(ident.name, kw::Empty);
                 let ident = self.lower_ident(ident);
-                let delegation_results = self.lower_delegation(delegation, id);
+                let delegation_results = self.lower_delegation(delegation, id, false);
                 hir::ItemKind::Fn {
                     ident,
                     sig: delegation_results.sig,
@@ -628,29 +625,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_assoc_item(
+    fn lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt) -> hir::OwnerNode<'hir> {
-        &mut self,
-        item: &AssocItem,
-        ctxt: AssocCtxt,
-        parent_hir: &'hir hir::OwnerInfo<'hir>,
-    ) -> hir::OwnerNode<'hir> {
-        let parent_item = parent_hir.node().expect_item();
-        match parent_item.kind {
-            hir::ItemKind::Impl(impl_) => {
-                self.is_in_trait_impl = impl_.of_trait.is_some();
-            }
-            hir::ItemKind::Trait(..) => {}
-            kind => {
-                span_bug!(item.span, "assoc item has unexpected kind of parent: {}", kind.descr())
-            }
-        }
-
         // Evaluate with the lifetimes in `params` in-scope.
         // This is used to track which lifetimes have already been defined,
         // and which need to be replicated when lowering an async fn.
         match ctxt {
             AssocCtxt::Trait => hir::OwnerNode::TraitItem(self.lower_trait_item(item)),
-            AssocCtxt::Impl => hir::OwnerNode::ImplItem(self.lower_impl_item(item)),
+            AssocCtxt::Impl { of_trait } => {
+                hir::OwnerNode::ImplItem(self.lower_impl_item(item, of_trait))
+            }
         }
     }
 
@@ -891,7 +874,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 (generics, kind, ty.is_some())
             }
             AssocItemKind::Delegation(box delegation) => {
-                let delegation_results = self.lower_delegation(delegation, i.id);
+                let delegation_results = self.lower_delegation(delegation, i.id, false);
                 let item_kind = hir::TraitItemKind::Fn(
                     delegation_results.sig,
                     hir::TraitFn::Provided(delegation_results.body_id),
@@ -922,7 +905,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 hir::AssocItemKind::Fn { has_self: sig.decl.has_self() }
             }
             AssocItemKind::Delegation(box delegation) => hir::AssocItemKind::Fn {
-                has_self: self.delegatee_is_method(i.id, delegation.id, i.span),
+                has_self: self.delegatee_is_method(i.id, delegation.id, i.span, false),
             },
             AssocItemKind::MacCall(..) | AssocItemKind::DelegationMac(..) => {
                 panic!("macros should have been expanded by now")
@@ -942,7 +925,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.expr(span, hir::ExprKind::Err(guar))
     }
 
-    fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> {
+    fn lower_impl_item(
+        &mut self,
+        i: &AssocItem,
+        is_in_trait_impl: bool,
+    ) -> &'hir hir::ImplItem<'hir> {
         debug_assert_ne!(i.ident.name, kw::Empty);
         // Since `default impl` is not yet implemented, this is always true in impls.
         let has_value = true;
@@ -978,7 +965,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     sig,
                     i.id,
-                    if self.is_in_trait_impl { FnDeclKind::Impl } else { FnDeclKind::Inherent },
+                    if is_in_trait_impl { FnDeclKind::Impl } else { FnDeclKind::Inherent },
                     sig.header.coroutine_kind,
                     attrs,
                 );
@@ -1018,7 +1005,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 )
             }
             AssocItemKind::Delegation(box delegation) => {
-                let delegation_results = self.lower_delegation(delegation, i.id);
+                let delegation_results = self.lower_delegation(delegation, i.id, is_in_trait_impl);
                 (
                     delegation_results.generics,
                     hir::ImplItemKind::Fn(delegation_results.sig, delegation_results.body_id),
@@ -1041,7 +1028,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.arena.alloc(item)
     }
 
-    fn lower_impl_item_ref(&mut self, i: &AssocItem) -> hir::ImplItemRef {
+    fn lower_impl_item_ref(&mut self, i: &AssocItem, is_in_trait_impl: bool) -> hir::ImplItemRef {
         hir::ImplItemRef {
             id: hir::ImplItemId { owner_id: self.owner_id(i.id) },
             ident: self.lower_ident(i.ident),
@@ -1053,7 +1040,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     hir::AssocItemKind::Fn { has_self: sig.decl.has_self() }
                 }
                 AssocItemKind::Delegation(box delegation) => hir::AssocItemKind::Fn {
-                    has_self: self.delegatee_is_method(i.id, delegation.id, i.span),
+                    has_self: self.delegatee_is_method(
+                        i.id,
+                        delegation.id,
+                        i.span,
+                        is_in_trait_impl,
+                    ),
                 },
                 AssocItemKind::MacCall(..) | AssocItemKind::DelegationMac(..) => {
                     panic!("macros should have been expanded by now")

compiler/rustc_ast_lowering/src/lib.rs

@@ -121,7 +121,6 @@ struct LoweringContext<'a, 'hir> {
     catch_scope: Option<HirId>,
     loop_scope: Option<HirId>,
     is_in_loop_condition: bool,
-    is_in_trait_impl: bool,
     is_in_dyn_type: bool,
 
     current_hir_id_owner: hir::OwnerId,
@@ -173,7 +172,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             catch_scope: None,
             loop_scope: None,
             is_in_loop_condition: false,
-            is_in_trait_impl: false,
             is_in_dyn_type: false,
             coroutine_kind: None,
             task_context: None,

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -860,7 +860,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     this.visit_trait_ref(t);
                     this.visit_ty(self_ty);
 
-                    walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl);
+                    walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl { of_trait: true });
                 });
                 walk_list!(self, visit_attribute, &item.attrs);
                 return; // Avoid visiting again.
@@ -913,7 +913,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         |this| this.visit_generics(generics),
                     );
                     this.visit_ty(self_ty);
-                    walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl);
+                    walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl { of_trait: false });
                 });
                 walk_list!(self, visit_attribute, &item.attrs);
                 return; // Avoid visiting again.
@@ -1414,7 +1414,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             self.check_defaultness(item.span, item.kind.defaultness());
         }
 
-        if ctxt == AssocCtxt::Impl {
+        if let AssocCtxt::Impl { .. } = ctxt {
             match &item.kind {
                 AssocItemKind::Const(box ConstItem { expr: None, .. }) => {
                     self.dcx().emit_err(errors::AssocConstWithoutBody {

compiler/rustc_builtin_macros/src/autodiff.rs

@@ -157,7 +157,7 @@ mod llvm_enzyme {
                 };
                 (sig.clone(), false)
             }
-            Annotatable::AssocItem(assoc_item, _) => {
+            Annotatable::AssocItem(assoc_item, Impl { of_trait: false }) => {
                 let sig = match &assoc_item.kind {
                     ast::AssocItemKind::Fn(box ast::Fn { sig, .. }) => sig,
                     _ => {
@@ -296,7 +296,7 @@ mod llvm_enzyme {
                 }
                 Annotatable::Item(iitem.clone())
             }
-            Annotatable::AssocItem(ref mut assoc_item, i @ Impl) => {
+            Annotatable::AssocItem(ref mut assoc_item, i @ Impl { of_trait: false }) => {
                 if !assoc_item.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
                     assoc_item.attrs.push(attr);
                 }
@@ -327,7 +327,7 @@ mod llvm_enzyme {
                 kind: assoc_item,
                 tokens: None,
             });
-            Annotatable::AssocItem(d_fn, Impl)
+            Annotatable::AssocItem(d_fn, Impl { of_trait: false })
         } else {
             let mut d_fn =
                 ecx.item(span, d_ident, thin_vec![d_attr, inline_never], ItemKind::Fn(asdf));

compiler/rustc_builtin_macros/src/cfg_eval.rs

@@ -121,18 +121,11 @@ impl CfgEval<'_> {
                     let item = parser.parse_item(ForceCollect::Yes)?.unwrap();
                     Annotatable::Item(self.flat_map_item(item).pop().unwrap())
                 }
-                Annotatable::AssocItem(_, AssocCtxt::Trait) => {
+                Annotatable::AssocItem(_, ctxt) => {
                     let item = parser.parse_trait_item(ForceCollect::Yes)?.unwrap().unwrap();
                     Annotatable::AssocItem(
-                        self.flat_map_assoc_item(item, AssocCtxt::Trait).pop().unwrap(),
+                        self.flat_map_assoc_item(item, ctxt).pop().unwrap(),
-                        AssocCtxt::Trait,
+                        ctxt,
-                    )
-                }
-                Annotatable::AssocItem(_, AssocCtxt::Impl) => {
-                    let item = parser.parse_impl_item(ForceCollect::Yes)?.unwrap().unwrap();
-                    Annotatable::AssocItem(
-                        self.flat_map_assoc_item(item, AssocCtxt::Impl).pop().unwrap(),
-                        AssocCtxt::Impl,
                     )
                 }
                 Annotatable::ForeignItem(_) => {

compiler/rustc_expand/src/base.rs

@@ -153,7 +153,7 @@ impl Annotatable {
 
     pub fn expect_impl_item(self) -> P<ast::AssocItem> {
         match self {
-            Annotatable::AssocItem(i, AssocCtxt::Impl) => i,
+            Annotatable::AssocItem(i, AssocCtxt::Impl { .. }) => i,
             _ => panic!("expected Item"),
         }
     }
@@ -403,6 +403,11 @@ pub trait MacResult {
         None
     }
 
+    /// Creates zero or more impl items.
+    fn make_trait_impl_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
+        None
+    }
+
     /// Creates zero or more trait items.
     fn make_trait_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
         None
@@ -516,6 +521,10 @@ impl MacResult for MacEager {
         self.impl_items
     }
 
+    fn make_trait_impl_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
+        self.impl_items
+    }
+
     fn make_trait_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
         self.trait_items
     }
@@ -613,6 +622,10 @@ impl MacResult for DummyResult {
         Some(SmallVec::new())
     }
 
+    fn make_trait_impl_items(self: Box<DummyResult>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
+        Some(SmallVec::new())
+    }
+
     fn make_trait_items(self: Box<DummyResult>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
         Some(SmallVec::new())
     }

compiler/rustc_expand/src/expand.rs

@@ -188,9 +188,15 @@ ast_fragments! {
     ImplItems(SmallVec<[P<ast::AssocItem>; 1]>) {
         "impl item";
         many fn flat_map_assoc_item;
-        fn visit_assoc_item(AssocCtxt::Impl);
+        fn visit_assoc_item(AssocCtxt::Impl { of_trait: false });
         fn make_impl_items;
     }
+    TraitImplItems(SmallVec<[P<ast::AssocItem>; 1]>) {
+        "impl item";
+        many fn flat_map_assoc_item;
+        fn visit_assoc_item(AssocCtxt::Impl { of_trait: true });
+        fn make_trait_impl_items;
+    }
     ForeignItems(SmallVec<[P<ast::ForeignItem>; 1]>) {
         "foreign item";
         many fn flat_map_foreign_item;
@@ -257,6 +263,7 @@ impl AstFragmentKind {
             AstFragmentKind::Items
             | AstFragmentKind::TraitItems
             | AstFragmentKind::ImplItems
+            | AstFragmentKind::TraitImplItems
             | AstFragmentKind::ForeignItems
             | AstFragmentKind::Crate => SupportsMacroExpansion::Yes { supports_inner_attrs: true },
             AstFragmentKind::Arms
@@ -306,6 +313,9 @@ impl AstFragmentKind {
             AstFragmentKind::ImplItems => {
                 AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect())
             }
+            AstFragmentKind::TraitImplItems => {
+                AstFragment::TraitImplItems(items.map(Annotatable::expect_impl_item).collect())
+            }
             AstFragmentKind::TraitItems => {
                 AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect())
             }
@@ -347,10 +357,10 @@ pub enum InvocationKind {
     },
     Attr {
         attr: ast::Attribute,
-        // Re-insertion position for inert attributes.
+        /// Re-insertion position for inert attributes.
         pos: usize,
         item: Annotatable,
-        // Required for resolving derive helper attributes.
+        /// Required for resolving derive helper attributes.
         derives: Vec<ast::Path>,
     },
     Derive {
@@ -360,6 +370,8 @@ pub enum InvocationKind {
     },
     GlobDelegation {
         item: P<ast::AssocItem>,
+        /// Whether this is a trait impl or an inherent impl
+        of_trait: bool,
     },
 }
 
@@ -388,7 +400,7 @@ impl Invocation {
             InvocationKind::Bang { span, .. } => *span,
             InvocationKind::Attr { attr, .. } => attr.span,
             InvocationKind::Derive { path, .. } => path.span,
-            InvocationKind::GlobDelegation { item } => item.span,
+            InvocationKind::GlobDelegation { item, .. } => item.span,
         }
     }
 
@@ -397,7 +409,7 @@ impl Invocation {
             InvocationKind::Bang { span, .. } => span,
             InvocationKind::Attr { attr, .. } => &mut attr.span,
             InvocationKind::Derive { path, .. } => &mut path.span,
-            InvocationKind::GlobDelegation { item } => &mut item.span,
+            InvocationKind::GlobDelegation { item, .. } => &mut item.span,
         }
     }
 }
@@ -820,7 +832,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 }
                 _ => unreachable!(),
             },
-            InvocationKind::GlobDelegation { item } => {
+            InvocationKind::GlobDelegation { item, of_trait } => {
                 let AssocItemKind::DelegationMac(deleg) = &item.kind else { unreachable!() };
                 let suffixes = match ext {
                     SyntaxExtensionKind::GlobDelegation(expander) => match expander.expand(self.cx)
@@ -829,7 +841,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         ExpandResult::Retry(()) => {
                             // Reassemble the original invocation for retrying.
                             return ExpandResult::Retry(Invocation {
-                                kind: InvocationKind::GlobDelegation { item },
+                                kind: InvocationKind::GlobDelegation { item, of_trait },
                                 ..invoc
                             });
                         }
@@ -847,7 +859,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     self.cx, deleg, &item, &suffixes, item.span, true,
                 );
                 fragment_kind.expect_from_annotatables(
-                    single_delegations.map(|item| Annotatable::AssocItem(P(item), AssocCtxt::Impl)),
+                    single_delegations
+                        .map(|item| Annotatable::AssocItem(P(item), AssocCtxt::Impl { of_trait })),
                 )
             }
         })
@@ -973,6 +986,13 @@ pub fn parse_ast_fragment<'a>(
             }
             AstFragment::ImplItems(items)
         }
+        AstFragmentKind::TraitImplItems => {
+            let mut items = SmallVec::new();
+            while let Some(item) = this.parse_impl_item(ForceCollect::No)? {
+                items.extend(item);
+            }
+            AstFragment::TraitImplItems(items)
+        }
         AstFragmentKind::ForeignItems => {
             let mut items = SmallVec::new();
             while let Some(item) = this.parse_foreign_item(ForceCollect::No)? {
@@ -1355,13 +1375,13 @@ impl InvocationCollectorNode for AstNodeWrapper<P<ast::AssocItem>, ImplItemTag>
     type ItemKind = AssocItemKind;
     const KIND: AstFragmentKind = AstFragmentKind::ImplItems;
     fn to_annotatable(self) -> Annotatable {
-        Annotatable::AssocItem(self.wrapped, AssocCtxt::Impl)
+        Annotatable::AssocItem(self.wrapped, AssocCtxt::Impl { of_trait: false })
     }
     fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
         fragment.make_impl_items()
     }
     fn walk_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
-        walk_flat_map_assoc_item(visitor, self.wrapped, AssocCtxt::Impl)
+        walk_flat_map_assoc_item(visitor, self.wrapped, AssocCtxt::Impl { of_trait: false })
     }
     fn is_mac_call(&self) -> bool {
         matches!(self.wrapped.kind, AssocItemKind::MacCall(..))
@@ -1390,6 +1410,47 @@ impl InvocationCollectorNode for AstNodeWrapper<P<ast::AssocItem>, ImplItemTag>
     }
 }
 
+struct TraitImplItemTag;
+impl InvocationCollectorNode for AstNodeWrapper<P<ast::AssocItem>, TraitImplItemTag> {
+    type OutputTy = SmallVec<[P<ast::AssocItem>; 1]>;
+    type ItemKind = AssocItemKind;
+    const KIND: AstFragmentKind = AstFragmentKind::TraitImplItems;
+    fn to_annotatable(self) -> Annotatable {
+        Annotatable::AssocItem(self.wrapped, AssocCtxt::Impl { of_trait: true })
+    }
+    fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
+        fragment.make_trait_impl_items()
+    }
+    fn walk_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
+        walk_flat_map_assoc_item(visitor, self.wrapped, AssocCtxt::Impl { of_trait: true })
+    }
+    fn is_mac_call(&self) -> bool {
+        matches!(self.wrapped.kind, AssocItemKind::MacCall(..))
+    }
+    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+        let item = self.wrapped.into_inner();
+        match item.kind {
+            AssocItemKind::MacCall(mac) => (mac, item.attrs, AddSemicolon::No),
+            _ => unreachable!(),
+        }
+    }
+    fn delegation(&self) -> Option<(&ast::DelegationMac, &ast::Item<Self::ItemKind>)> {
+        match &self.wrapped.kind {
+            AssocItemKind::DelegationMac(deleg) => Some((deleg, &self.wrapped)),
+            _ => None,
+        }
+    }
+    fn delegation_item_kind(deleg: Box<ast::Delegation>) -> Self::ItemKind {
+        AssocItemKind::Delegation(deleg)
+    }
+    fn from_item(item: ast::Item<Self::ItemKind>) -> Self {
+        AstNodeWrapper::new(P(item), TraitImplItemTag)
+    }
+    fn flatten_outputs(items: impl Iterator<Item = Self::OutputTy>) -> Self::OutputTy {
+        items.flatten().collect()
+    }
+}
+
 impl InvocationCollectorNode for P<ast::ForeignItem> {
     const KIND: AstFragmentKind = AstFragmentKind::ForeignItems;
     fn to_annotatable(self) -> Annotatable {
@@ -1855,9 +1916,10 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
     fn collect_glob_delegation(
         &mut self,
         item: P<ast::AssocItem>,
+        of_trait: bool,
         kind: AstFragmentKind,
     ) -> AstFragment {
-        self.collect(kind, InvocationKind::GlobDelegation { item })
+        self.collect(kind, InvocationKind::GlobDelegation { item, of_trait })
     }
 
     /// If `item` is an attribute invocation, remove the attribute and return it together with
@@ -2030,8 +2092,10 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                     let Some(suffixes) = &deleg.suffixes else {
                         let traitless_qself =
                             matches!(&deleg.qself, Some(qself) if qself.position == 0);
-                        let item = match node.to_annotatable() {
+                        let (item, of_trait) = match node.to_annotatable() {
-                            Annotatable::AssocItem(item, AssocCtxt::Impl) => item,
+                            Annotatable::AssocItem(item, AssocCtxt::Impl { of_trait }) => {
+                                (item, of_trait)
+                            }
                             ann @ (Annotatable::Item(_)
                             | Annotatable::AssocItem(..)
                             | Annotatable::Stmt(_)) => {
@@ -2046,7 +2110,9 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                             self.cx.dcx().emit_err(GlobDelegationTraitlessQpath { span });
                             return Default::default();
                         }
-                        return self.collect_glob_delegation(item, Node::KIND).make_ast::<Node>();
+                        return self
+                            .collect_glob_delegation(item, of_trait, Node::KIND)
+                            .make_ast::<Node>();
                     };
 
                     let single_delegations = build_single_delegations::<Node>(
@@ -2126,7 +2192,12 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
     ) -> SmallVec<[P<ast::AssocItem>; 1]> {
         match ctxt {
             AssocCtxt::Trait => self.flat_map_node(AstNodeWrapper::new(node, TraitItemTag)),
-            AssocCtxt::Impl => self.flat_map_node(AstNodeWrapper::new(node, ImplItemTag)),
+            AssocCtxt::Impl { of_trait: false } => {
+                self.flat_map_node(AstNodeWrapper::new(node, ImplItemTag))
+            }
+            AssocCtxt::Impl { of_trait: true } => {
+                self.flat_map_node(AstNodeWrapper::new(node, TraitImplItemTag))
+            }
         }
     }
 

compiler/rustc_expand/src/placeholders.rs

@@ -86,6 +86,17 @@ pub(crate) fn placeholder(
             kind: ast::AssocItemKind::MacCall(mac_placeholder()),
             tokens: None,
         })]),
+        AstFragmentKind::TraitImplItems => {
+            AstFragment::TraitImplItems(smallvec![P(ast::AssocItem {
+                id,
+                span,
+                ident,
+                vis,
+                attrs,
+                kind: ast::AssocItemKind::MacCall(mac_placeholder()),
+                tokens: None,
+            })])
+        }
         AstFragmentKind::ForeignItems => {
             AstFragment::ForeignItems(smallvec![P(ast::ForeignItem {
                 id,
@@ -308,7 +319,8 @@ impl MutVisitor for PlaceholderExpander {
                 let it = self.remove(item.id);
                 match ctxt {
                     AssocCtxt::Trait => it.make_trait_items(),
-                    AssocCtxt::Impl => it.make_impl_items(),
+                    AssocCtxt::Impl { of_trait: false } => it.make_impl_items(),
+                    AssocCtxt::Impl { of_trait: true } => it.make_trait_impl_items(),
                 }
             }
             _ => walk_flat_map_assoc_item(self, item, ctxt),

compiler/rustc_lint/src/early.rs

@@ -241,7 +241,7 @@ impl<'ast, 'ecx, 'tcx, T: EarlyLintPass> ast_visit::Visitor<'ast>
                 ast_visit::AssocCtxt::Trait => {
                     lint_callback!(cx, check_trait_item, item);
                 }
-                ast_visit::AssocCtxt::Impl => {
+                ast_visit::AssocCtxt::Impl { .. } => {
                     lint_callback!(cx, check_impl_item, item);
                 }
             }
@@ -250,7 +250,7 @@ impl<'ast, 'ecx, 'tcx, T: EarlyLintPass> ast_visit::Visitor<'ast>
                 ast_visit::AssocCtxt::Trait => {
                     lint_callback!(cx, check_trait_item_post, item);
                 }
-                ast_visit::AssocCtxt::Impl => {
+                ast_visit::AssocCtxt::Impl { .. } => {
                     lint_callback!(cx, check_impl_item_post, item);
                 }
             }

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -884,10 +884,10 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             }
 
             // These items do not add names to modules.
-            ItemKind::Impl(box Impl { of_trait: Some(..), .. }) => {
+            ItemKind::Impl(box Impl { of_trait: Some(..), .. })
-                self.r.trait_impl_items.insert(local_def_id);
+            | ItemKind::Impl { .. }
-            }
+            | ItemKind::ForeignMod(..)
-            ItemKind::Impl { .. } | ItemKind::ForeignMod(..) | ItemKind::GlobalAsm(..) => {}
+            | ItemKind::GlobalAsm(..) => {}
 
             ItemKind::MacroDef(..) | ItemKind::MacCall(_) | ItemKind::DelegationMac(..) => {
                 unreachable!()
@@ -1377,7 +1377,7 @@ impl<'a, 'ra, 'tcx> Visitor<'a> for BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                 AssocCtxt::Trait => {
                     self.visit_invoc_in_module(item.id);
                 }
-                AssocCtxt::Impl => {
+                AssocCtxt::Impl { .. } => {
                     let invoc_id = item.id.placeholder_to_expn_id();
                     if !self.r.glob_delegation_invoc_ids.contains(&invoc_id) {
                         self.r
@@ -1397,9 +1397,8 @@ impl<'a, 'ra, 'tcx> Visitor<'a> for BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
         let local_def_id = feed.key();
         let def_id = local_def_id.to_def_id();
 
-        if !(ctxt == AssocCtxt::Impl
+        if !(matches!(ctxt, AssocCtxt::Impl { of_trait: true })
-            && matches!(item.vis.kind, ast::VisibilityKind::Inherited)
+            && matches!(item.vis.kind, ast::VisibilityKind::Inherited))
-            && self.r.trait_impl_items.contains(&self.r.tcx.local_parent(local_def_id)))
         {
             // Trait impl item visibility is inherited from its trait when not specified
             // explicitly. In that case we cannot determine it here in early resolve,

compiler/rustc_resolve/src/late.rs

@@ -3375,7 +3375,7 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                             |i, s, c| MethodNotMemberOfTrait(i, s, c),
                         );
 
-                        visit::walk_assoc_item(this, item, AssocCtxt::Impl)
+                        visit::walk_assoc_item(this, item, AssocCtxt::Impl { of_trait: true })
                     },
                 );
 
@@ -3409,7 +3409,7 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                                 |i, s, c| TypeNotMemberOfTrait(i, s, c),
                             );
 
-                            visit::walk_assoc_item(this, item, AssocCtxt::Impl)
+                            visit::walk_assoc_item(this, item, AssocCtxt::Impl { of_trait: true })
                         });
                     },
                 );

compiler/rustc_resolve/src/lib.rs

@@ -1191,10 +1191,6 @@ pub struct Resolver<'ra, 'tcx> {
     /// and how the `impl Trait` fragments were introduced.
     invocation_parents: FxHashMap<LocalExpnId, InvocationParent>,
 
-    /// Some way to know that we are in a *trait* impl in `visit_assoc_item`.
-    /// FIXME: Replace with a more general AST map (together with some other fields).
-    trait_impl_items: FxHashSet<LocalDefId>,
-
     legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
     /// Amount of lifetime parameters for each item in the crate.
     item_generics_num_lifetimes: FxHashMap<LocalDefId, usize>,
@@ -1558,7 +1554,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             def_id_to_node_id,
             placeholder_field_indices: Default::default(),
             invocation_parents,
-            trait_impl_items: Default::default(),
             legacy_const_generic_args: Default::default(),
             item_generics_num_lifetimes: Default::default(),
             main_def: Default::default(),

compiler/rustc_resolve/src/macros.rs

@@ -264,7 +264,7 @@ impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> {
             }
             InvocationKind::Bang { ref mac, .. } => (&mac.path, MacroKind::Bang),
             InvocationKind::Derive { ref path, .. } => (path, MacroKind::Derive),
-            InvocationKind::GlobDelegation { ref item } => {
+            InvocationKind::GlobDelegation { ref item, .. } => {
                 let ast::AssocItemKind::DelegationMac(deleg) = &item.kind else { unreachable!() };
                 deleg_impl = Some(self.invocation_parent(invoc_id));
                 // It is sufficient to consider glob delegation a bang macro for now.

src/tools/rustfmt/src/visitor.rs

@@ -624,7 +624,8 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
         // TODO(calebcartwright): Not sure the skip spans are correct
         let (ai, skip_span, assoc_ctxt) = match visitor_kind {
             AssocTraitItem(ai) => (*ai, ai.span(), visit::AssocCtxt::Trait),
-            AssocImplItem(ai) => (*ai, ai.span, visit::AssocCtxt::Impl),
+            // There is no difference between trait and inherent assoc item formatting
+            AssocImplItem(ai) => (*ai, ai.span, visit::AssocCtxt::Impl { of_trait: false }),
             _ => unreachable!(),
         };
         skip_out_of_file_lines_range_visitor!(self, ai.span);