Box FunctionItem, TyMethodItem, MethodItem, ForeignFunctionItem

This reduces ItemKind size from 160 bytes to 112 bytes

src/librustdoc/clean/inline.rs

@@ -218,7 +218,7 @@ pub(crate) fn build_external_trait(cx: &mut DocContext<'_>, did: DefId) -> clean
     clean::Trait { def_id: did, generics, items: trait_items, bounds: supertrait_bounds }
 }
 
-fn build_external_function<'tcx>(cx: &mut DocContext<'tcx>, did: DefId) -> clean::Function {
+fn build_external_function<'tcx>(cx: &mut DocContext<'tcx>, did: DefId) -> Box<clean::Function> {
     let sig = cx.tcx.fn_sig(did);
 
     let predicates = cx.tcx.predicates_of(did);
@@ -228,7 +228,7 @@ fn build_external_function<'tcx>(cx: &mut DocContext<'tcx>, did: DefId) -> clean
         let decl = clean_fn_decl_from_did_and_sig(cx, Some(did), sig);
         (generics, decl)
     });
-    clean::Function { decl, generics }
+    Box::new(clean::Function { decl, generics })
 }
 
 fn build_enum(cx: &mut DocContext<'_>, did: DefId) -> clean::Enum {

src/librustdoc/clean/mod.rs

@@ -908,7 +908,7 @@ fn clean_function<'tcx>(
     sig: &hir::FnSig<'tcx>,
     generics: &hir::Generics<'tcx>,
     body_id: hir::BodyId,
-) -> Function {
+) -> Box<Function> {
     let (generics, decl) = enter_impl_trait(cx, |cx| {
         // NOTE: generics must be cleaned before args
         let generics = generics.clean(cx);
@@ -916,7 +916,7 @@ fn clean_function<'tcx>(
         let decl = clean_fn_decl_with_args(cx, sig.decl, args);
         (generics, decl)
     });
-    Function { decl, generics }
+    Box::new(Function { decl, generics })
 }
 
 fn clean_args_from_types_and_names<'tcx>(
@@ -1061,7 +1061,7 @@ impl<'tcx> Clean<'tcx, Item> for hir::TraitItem<'tcx> {
                         let decl = clean_fn_decl_with_args(cx, sig.decl, args);
                         (generics, decl)
                     });
-                    TyMethodItem(Function { decl, generics })
+                    TyMethodItem(Box::new(Function { decl, generics }))
                 }
                 hir::TraitItemKind::Type(bounds, Some(default)) => {
                     let generics = enter_impl_trait(cx, |cx| self.generics.clean(cx));
@@ -1186,9 +1186,9 @@ impl<'tcx> Clean<'tcx, Item> for ty::AssocItem {
                         ty::ImplContainer(_) => Some(self.defaultness),
                         ty::TraitContainer(_) => None,
                     };
-                    MethodItem(Function { generics, decl }, defaultness)
+                    MethodItem(Box::new(Function { generics, decl }), defaultness)
                 } else {
-                    TyMethodItem(Function { generics, decl })
+                    TyMethodItem(Box::new(Function { generics, decl }))
                 }
             }
             ty::AssocKind::Type => {
@@ -2243,7 +2243,7 @@ fn clean_maybe_renamed_foreign_item<'tcx>(
                     let decl = clean_fn_decl_with_args(cx, decl, args);
                     (generics, decl)
                 });
-                ForeignFunctionItem(Function { decl, generics })
+                ForeignFunctionItem(Box::new(Function { decl, generics }))
             }
             hir::ForeignItemKind::Static(ty, mutability) => {
                 ForeignStaticItem(Static { type_: clean_ty(ty, cx), mutability, expr: None })

src/librustdoc/clean/types.rs

@@ -730,7 +730,7 @@ pub(crate) enum ItemKind {
     StructItem(Struct),
     UnionItem(Union),
     EnumItem(Enum),
-    FunctionItem(Function),
+    FunctionItem(Box<Function>),
     ModuleItem(Module),
     TypedefItem(Box<Typedef>),
     OpaqueTyItem(OpaqueTy),
@@ -740,15 +740,15 @@ pub(crate) enum ItemKind {
     TraitAliasItem(TraitAlias),
     ImplItem(Box<Impl>),
     /// A required method in a trait declaration meaning it's only a function signature.
-    TyMethodItem(Function),
+    TyMethodItem(Box<Function>),
     /// A method in a trait impl or a provided method in a trait declaration.
     ///
     /// Compared to [TyMethodItem], it also contains a method body.
-    MethodItem(Function, Option<hir::Defaultness>),
+    MethodItem(Box<Function>, Option<hir::Defaultness>),
     StructFieldItem(Type),
     VariantItem(Variant),
     /// `fn`s from an extern block
-    ForeignFunctionItem(Function),
+    ForeignFunctionItem(Box<Function>),
     /// `static`s from an extern block
     ForeignStaticItem(Static),
     /// `type`s from an extern block

src/librustdoc/json/conversions.rs

@@ -602,11 +602,11 @@ impl FromWithTcx<Box<clean::Impl>> for Impl {
 }
 
 pub(crate) fn from_function(
-    function: clean::Function,
+    function: Box<clean::Function>,
     header: rustc_hir::FnHeader,
     tcx: TyCtxt<'_>,
 ) -> Function {
-    let clean::Function { decl, generics } = function;
+    let clean::Function { decl, generics } = *function;
     Function {
         decl: decl.into_tcx(tcx),
         generics: generics.into_tcx(tcx),
@@ -615,12 +615,12 @@ pub(crate) fn from_function(
 }
 
 pub(crate) fn from_function_method(
-    function: clean::Function,
+    function: Box<clean::Function>,
     has_body: bool,
     header: rustc_hir::FnHeader,
     tcx: TyCtxt<'_>,
 ) -> Method {
-    let clean::Function { decl, generics } = function;
+    let clean::Function { decl, generics } = *function;
     Method {
         decl: decl.into_tcx(tcx),
         generics: generics.into_tcx(tcx),