Auto merge of rust-lang#138929 - oli-obk:assoc-ctxt-of-trait, r=<try>

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.

Author: bors

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 {
-        let sig_id = self.get_delegation_sig_id(item_id, path_id, span);
+    pub(crate) fn delegatee_is_method(
+        &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];
-        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))
+        self.with_lctx(item.id, |lctx| lctx.lower_assoc_item(item, ctxt))
     }
 
     fn lower_foreign_item(&mut self, item: &ForeignItem) {
@@ -408,10 +404,11 @@ 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(impl_items.iter().map(|item| self.lower_impl_item_ref(item)));
+                let new_impl_items = self.arena.alloc_from_iter(
+                    impl_items
+                        .iter()
+                        .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.
@@ -488,7 +485,7 @@ 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,
@@ -631,29 +628,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_assoc_item(
-        &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())
-            }
-        }
-
+    fn lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt) -> hir::OwnerNode<'hir> {
         // 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))
+            }
         }
     }
 
@@ -894,7 +877,7 @@ 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),
@@ -925,7 +908,7 @@ 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")
@@ -945,7 +928,11 @@ 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;
@@ -981,7 +968,7 @@ 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,
                 );
@@ -1021,7 +1008,7 @@ 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),
@@ -1044,7 +1031,7 @@ 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: hir::OwnerId { def_id: self.local_def_id(i.id) } },
             ident: self.lower_ident(i.ident),
@@ -1056,7 +1043,12 @@ 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(),
-                        AssocCtxt::Trait,
-                    )
-                }
-                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,
+                        self.flat_map_assoc_item(item, ctxt).pop().unwrap(),
+                        ctxt,
                     )
                 }
                 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())
     }