rustdoc: use a single box to store Attributes and ItemKind

rust-lang · matthiaskrgr · Jul 13, 2024 · Aug 6, 2024 · Aug 6, 2024 · Aug 9, 2024
commit a3127ca721620a1a276d98942d4db266c54b3add
diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs
@@ -114,17 +114,19 @@ fn synthesize_auto_trait_impl<'tcx>(
 
     Some(clean::Item {
         name: None,
-        attrs: Default::default(),
+        inner: Box::new(clean::ItemInner {
+            attrs: Default::default(),
+            kind: clean::ImplItem(Box::new(clean::Impl {
+                safety: hir::Safety::Safe,
+                generics,
+                trait_: Some(clean_trait_ref_with_constraints(cx, trait_ref, ThinVec::new())),
+                for_: clean_middle_ty(ty::Binder::dummy(ty), cx, None, None),
+                items: Vec::new(),
+                polarity,
+                kind: clean::ImplKind::Auto,
+            })),
+        }),
         item_id: clean::ItemId::Auto { trait_: trait_def_id, for_: item_def_id },
-        kind: Box::new(clean::ImplItem(Box::new(clean::Impl {
-            safety: hir::Safety::Safe,
-            generics,
-            trait_: Some(clean_trait_ref_with_constraints(cx, trait_ref, ThinVec::new())),
-            for_: clean_middle_ty(ty::Binder::dummy(ty), cx, None, None),
-            items: Vec::new(),
-            polarity,
-            kind: clean::ImplKind::Auto,
-        }))),
         cfg: None,
         inline_stmt_id: None,
     })

diff --git a/src/librustdoc/clean/blanket_impl.rs b/src/librustdoc/clean/blanket_impl.rs
@@ -83,42 +83,44 @@ pub(crate) fn synthesize_blanket_impls(
 
             blanket_impls.push(clean::Item {
                 name: None,
-                attrs: Default::default(),
                 item_id: clean::ItemId::Blanket { impl_id: impl_def_id, for_: item_def_id },
-                kind: Box::new(clean::ImplItem(Box::new(clean::Impl {
-                    safety: hir::Safety::Safe,
-                    generics: clean_ty_generics(
-                        cx,
-                        tcx.generics_of(impl_def_id),
-                        tcx.explicit_predicates_of(impl_def_id),
-                    ),
-                    // FIXME(eddyb) compute both `trait_` and `for_` from
-                    // the post-inference `trait_ref`, as it's more accurate.
-                    trait_: Some(clean_trait_ref_with_constraints(
-                        cx,
-                        ty::Binder::dummy(trait_ref.instantiate_identity()),
-                        ThinVec::new(),
-                    )),
-                    for_: clean_middle_ty(
-                        ty::Binder::dummy(ty.instantiate_identity()),
-                        cx,
-                        None,
-                        None,
-                    ),
-                    items: tcx
-                        .associated_items(impl_def_id)
-                        .in_definition_order()
-                        .filter(|item| !item.is_impl_trait_in_trait())
-                        .map(|item| clean_middle_assoc_item(item, cx))
-                        .collect(),
-                    polarity: ty::ImplPolarity::Positive,
-                    kind: clean::ImplKind::Blanket(Box::new(clean_middle_ty(
-                        ty::Binder::dummy(trait_ref.instantiate_identity().self_ty()),
-                        cx,
-                        None,
-                        None,
-                    ))),
-                }))),
+                inner: Box::new(clean::ItemInner {
+                    attrs: Default::default(),
+                    kind: clean::ImplItem(Box::new(clean::Impl {
+                        safety: hir::Safety::Safe,
+                        generics: clean_ty_generics(
+                            cx,
+                            tcx.generics_of(impl_def_id),
+                            tcx.explicit_predicates_of(impl_def_id),
+                        ),
+                        // FIXME(eddyb) compute both `trait_` and `for_` from
+                        // the post-inference `trait_ref`, as it's more accurate.
+                        trait_: Some(clean_trait_ref_with_constraints(
+                            cx,
+                            ty::Binder::dummy(trait_ref.instantiate_identity()),
+                            ThinVec::new(),
+                        )),
+                        for_: clean_middle_ty(
+                            ty::Binder::dummy(ty.instantiate_identity()),
+                            cx,
+                            None,
+                            None,
+                        ),
+                        items: tcx
+                            .associated_items(impl_def_id)
+                            .in_definition_order()
+                            .filter(|item| !item.is_impl_trait_in_trait())
+                            .map(|item| clean_middle_assoc_item(item, cx))
+                            .collect(),
+                        polarity: ty::ImplPolarity::Positive,
+                        kind: clean::ImplKind::Blanket(Box::new(clean_middle_ty(
+                            ty::Binder::dummy(trait_ref.instantiate_identity().self_ty()),
+                            cx,
+                            None,
+                            None,
+                        ))),
+                    })),
+                }),
                 cfg: None,
                 inline_stmt_id: None,
             });

diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
@@ -151,14 +151,8 @@ pub(crate) fn try_inline(
     };
 
     cx.inlined.insert(did.into());
-    let mut item = crate::clean::generate_item_with_correct_attrs(
-        cx,
-        kind,
-        did,
-        name,
-        import_def_id,
-        None,
-    );
+    let mut item =
+        crate::clean::generate_item_with_correct_attrs(cx, kind, did, name, import_def_id, None);
     // The visibility needs to reflect the one from the reexport and not from the "source" DefId.
     item.inline_stmt_id = import_def_id;
     ret.push(item);
@@ -622,7 +616,7 @@ pub(crate) fn build_impl(
                 ImplKind::Normal
             },
         })),
-        Box::new(merged_attrs),
+        merged_attrs,
         cfg,
     ));
 }
@@ -672,27 +666,29 @@ fn build_module_items(
                 let prim_ty = clean::PrimitiveType::from(p);
                 items.push(clean::Item {
                     name: None,
-                    attrs: Box::default(),
                     // We can use the item's `DefId` directly since the only information ever used
                     // from it is `DefId.krate`.
                     item_id: ItemId::DefId(did),
-                    kind: Box::new(clean::ImportItem(clean::Import::new_simple(
-                        item.ident.name,
-                        clean::ImportSource {
-                            path: clean::Path {
-                                res,
-                                segments: thin_vec![clean::PathSegment {
-                                    name: prim_ty.as_sym(),
-                                    args: clean::GenericArgs::AngleBracketed {
-                                        args: Default::default(),
-                                        constraints: ThinVec::new(),
-                                    },
-                                }],
+                    inner: Box::new(clean::ItemInner {
+                        attrs: Default::default(),
+                        kind: clean::ImportItem(clean::Import::new_simple(
+                            item.ident.name,
+                            clean::ImportSource {
+                                path: clean::Path {
+                                    res,
+                                    segments: thin_vec![clean::PathSegment {
+                                        name: prim_ty.as_sym(),
+                                        args: clean::GenericArgs::AngleBracketed {
+                                            args: Default::default(),
+                                            constraints: ThinVec::new(),
+                                        },
+                                    }],
+                                },
+                                did: None,
                             },
-                            did: None,
-                        },
-                        true,
-                    ))),
+                            true,
+                        )),
+                    }),
                     cfg: None,
                     inline_stmt_id: None,
                 });
@@ -752,7 +748,8 @@ fn build_macro(
         LoadedMacro::MacroDef(item_def, _) => match macro_kind {
             MacroKind::Bang => {
                 if let ast::ItemKind::MacroDef(ref def) = item_def.kind {
-                    let vis = cx.tcx.visibility(import_def_id.map(|d| d.to_def_id()).unwrap_or(def_id));
+                    let vis =
+                        cx.tcx.visibility(import_def_id.map(|d| d.to_def_id()).unwrap_or(def_id));
                     clean::MacroItem(clean::Macro {
                         source: utils::display_macro_source(
                             cx,

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
@@ -202,7 +202,7 @@ fn generate_item_with_correct_attrs(
     let attrs = Attributes::from_ast_iter(attrs.iter().map(|(attr, did)| (&**attr, *did)), false);
 
     let name = renamed.or(Some(name));
-    let mut item = Item::from_def_id_and_attrs_and_parts(def_id, name, kind, Box::new(attrs), cfg);
+    let mut item = Item::from_def_id_and_attrs_and_parts(def_id, name, kind, attrs, cfg);
     item.inline_stmt_id = import_id;
     item
 }

diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
@@ -319,10 +319,7 @@ pub(crate) struct Item {
     /// The name of this item.
     /// Optional because not every item has a name, e.g. impls.
     pub(crate) name: Option<Symbol>,
-    pub(crate) attrs: Box<Attributes>,
-    /// Information about this item that is specific to what kind of item it is.
-    /// E.g., struct vs enum vs function.
-    pub(crate) kind: Box<ItemKind>,
+    pub(crate) inner: Box<ItemInner>,
     pub(crate) item_id: ItemId,
     /// This is the `LocalDefId` of the `use` statement if the item was inlined.
     /// The crate metadata doesn't hold this information, so the `use` statement
@@ -331,6 +328,21 @@ pub(crate) struct Item {
     pub(crate) cfg: Option<Arc<Cfg>>,
 }
 
+#[derive(Clone)]
+pub(crate) struct ItemInner {
+    /// Information about this item that is specific to what kind of item it is.
+    /// E.g., struct vs enum vs function.
+    pub(crate) kind: ItemKind,
+    pub(crate) attrs: Attributes,
+}
+
+impl std::ops::Deref for Item {
+    type Target = ItemInner;
+    fn deref(&self) -> &ItemInner {
+        &*self.inner
+    }
+}
+
 /// NOTE: this does NOT unconditionally print every item, to avoid thousands of lines of logs.
 /// If you want to see the debug output for attributes and the `kind` as well, use `{:#?}` instead of `{:?}`.
 impl fmt::Debug for Item {
@@ -390,9 +402,9 @@ impl Item {
     }
 
     pub(crate) fn span(&self, tcx: TyCtxt<'_>) -> Option<Span> {
-        let kind = match &*self.kind {
-            ItemKind::StrippedItem(k) => k,
-            _ => &*self.kind,
+        let kind = match &self.kind {
+            ItemKind::StrippedItem(k) => &*k,
+            _ => &self.kind,
         };
         match kind {
             ItemKind::ModuleItem(Module { span, .. }) => Some(*span),
@@ -437,7 +449,7 @@ impl Item {
             def_id,
             name,
             kind,
-            Box::new(Attributes::from_ast(ast_attrs)),
+            Attributes::from_ast(ast_attrs),
             ast_attrs.cfg(cx.tcx, &cx.cache.hidden_cfg),
         )
     }
@@ -446,16 +458,15 @@ impl Item {
         def_id: DefId,
         name: Option<Symbol>,
         kind: ItemKind,
-        attrs: Box<Attributes>,
+        attrs: Attributes,
         cfg: Option<Arc<Cfg>>,
     ) -> Item {
         trace!("name={name:?}, def_id={def_id:?} cfg={cfg:?}");
 
         Item {
             item_id: def_id.into(),
-            kind: Box::new(kind),
+            inner: Box::new(ItemInner { kind, attrs }),
             name,
-            attrs,
             cfg,
             inline_stmt_id: None,
         }
@@ -526,16 +537,16 @@ impl Item {
         self.type_() == ItemType::Variant
     }
     pub(crate) fn is_associated_type(&self) -> bool {
-        matches!(&*self.kind, AssocTypeItem(..) | StrippedItem(box AssocTypeItem(..)))
+        matches!(self.kind, AssocTypeItem(..) | StrippedItem(box AssocTypeItem(..)))
     }
     pub(crate) fn is_ty_associated_type(&self) -> bool {
-        matches!(&*self.kind, TyAssocTypeItem(..) | StrippedItem(box TyAssocTypeItem(..)))
+        matches!(self.kind, TyAssocTypeItem(..) | StrippedItem(box TyAssocTypeItem(..)))
     }
     pub(crate) fn is_associated_const(&self) -> bool {
-        matches!(&*self.kind, AssocConstItem(..) | StrippedItem(box AssocConstItem(..)))
+        matches!(self.kind, AssocConstItem(..) | StrippedItem(box AssocConstItem(..)))
     }
     pub(crate) fn is_ty_associated_const(&self) -> bool {
-        matches!(&*self.kind, TyAssocConstItem(..) | StrippedItem(box TyAssocConstItem(..)))
+        matches!(self.kind, TyAssocConstItem(..) | StrippedItem(box TyAssocConstItem(..)))
     }
     pub(crate) fn is_method(&self) -> bool {
         self.type_() == ItemType::Method
@@ -562,14 +573,14 @@ impl Item {
         self.type_() == ItemType::Keyword
     }
     pub(crate) fn is_stripped(&self) -> bool {
-        match *self.kind {
+        match self.kind {
             StrippedItem(..) => true,
             ImportItem(ref i) => !i.should_be_displayed,
             _ => false,
         }
     }
     pub(crate) fn has_stripped_entries(&self) -> Option<bool> {
-        match *self.kind {
+        match self.kind {
             StructItem(ref struct_) => Some(struct_.has_stripped_entries()),
             UnionItem(ref union_) => Some(union_.has_stripped_entries()),
             EnumItem(ref enum_) => Some(enum_.has_stripped_entries()),
@@ -612,7 +623,7 @@ impl Item {
     }
 
     pub(crate) fn is_default(&self) -> bool {
-        match *self.kind {
+        match self.kind {
             ItemKind::MethodItem(_, Some(defaultness)) => {
                 defaultness.has_value() && !defaultness.is_final()
             }
@@ -640,7 +651,7 @@ impl Item {
             };
             hir::FnHeader { safety: sig.safety(), abi: sig.abi(), constness, asyncness }
         }
-        let header = match *self.kind {
+        let header = match self.kind {
             ItemKind::ForeignFunctionItem(_, safety) => {
                 let def_id = self.def_id().unwrap();
                 let abi = tcx.fn_sig(def_id).skip_binder().abi();
@@ -679,7 +690,7 @@ impl Item {
             ItemId::DefId(def_id) => def_id,
         };
 
-        match *self.kind {
+        match self.kind {
             // Primitives and Keywords are written in the source code as private modules.
             // The modules need to be private so that nobody actually uses them, but the
             // keywords and primitives that they are documenting are public.
@@ -2566,13 +2577,13 @@ mod size_asserts {
 
     use super::*;
     // tidy-alphabetical-start
-    static_assert_size!(Crate, 64); // frequently moved by-value
+    static_assert_size!(Crate, 56); // frequently moved by-value
     static_assert_size!(DocFragment, 32);
     static_assert_size!(GenericArg, 32);
     static_assert_size!(GenericArgs, 32);
     static_assert_size!(GenericParamDef, 40);
     static_assert_size!(Generics, 16);
-    static_assert_size!(Item, 56);
+    static_assert_size!(Item, 48);
     static_assert_size!(ItemKind, 48);
     static_assert_size!(PathSegment, 40);
     static_assert_size!(Type, 32);

diff --git a/src/librustdoc/clean/utils.rs b/src/librustdoc/clean/utils.rs
@@ -35,7 +35,7 @@ pub(crate) fn krate(cx: &mut DocContext<'_>) -> Crate {
     // understood by rustdoc.
     let mut module = clean_doc_module(&module, cx);
 
-    match *module.kind {
+    match module.kind {
         ItemKind::ModuleItem(ref module) => {
             for it in &module.items {
                 // `compiler_builtins` should be masked too, but we can't apply
@@ -59,7 +59,7 @@ pub(crate) fn krate(cx: &mut DocContext<'_>) -> Crate {
     let primitives = local_crate.primitives(cx.tcx);
     let keywords = local_crate.keywords(cx.tcx);
     {
-        let ItemKind::ModuleItem(ref mut m) = *module.kind else { unreachable!() };
+        let ItemKind::ModuleItem(ref mut m) = &mut module.inner.kind else { unreachable!() };
         m.items.extend(primitives.iter().map(|&(def_id, prim)| {
             Item::from_def_id_and_parts(
                 def_id,
@@ -280,7 +280,7 @@ pub(crate) fn build_deref_target_impls(
     let tcx = cx.tcx;
 
     for item in items {
-        let target = match *item.kind {
+        let target = match item.kind {
             ItemKind::AssocTypeItem(ref t, _) => &t.type_,
             _ => continue,
         };