Rollup merge of #117070 - notriddle:notriddle/cleanx, r=fmease

rustdoc: wrap Type with Box instead of Generics

When these `Box<Generics>` types were introduced, `Generics` was made with `Vec` and much larger. Now that it's made with `ThinVec`, `Type` is bigger and should be boxed instead.

src/librustdoc/clean/inline.rs

@@ -641,13 +641,13 @@ fn build_const(cx: &mut DocContext<'_>, def_id: DefId) -> clean::Constant {
     clean::simplify::move_bounds_to_generic_parameters(&mut generics);
 
     clean::Constant {
-        type_: clean_middle_ty(
+        type_: Box::new(clean_middle_ty(
             ty::Binder::dummy(cx.tcx.type_of(def_id).instantiate_identity()),
             cx,
             Some(def_id),
             None,
-        ),
+        )),
-        generics: Box::new(generics),
+        generics,
         kind: clean::ConstantKind::Extern { def_id },
     }
 }

src/librustdoc/clean/mod.rs

@@ -259,13 +259,13 @@ fn clean_lifetime<'tcx>(lifetime: &hir::Lifetime, cx: &mut DocContext<'tcx>) ->
 pub(crate) fn clean_const<'tcx>(constant: &hir::ConstArg, cx: &mut DocContext<'tcx>) -> Constant {
     let def_id = cx.tcx.hir().body_owner_def_id(constant.value.body).to_def_id();
     Constant {
-        type_: clean_middle_ty(
+        type_: Box::new(clean_middle_ty(
             ty::Binder::dummy(cx.tcx.type_of(def_id).instantiate_identity()),
             cx,
             Some(def_id),
             None,
-        ),
+        )),
-        generics: Box::new(Generics::default()),
+        generics: Generics::default(),
         kind: ConstantKind::Anonymous { body: constant.value.body },
     }
 }
@@ -276,8 +276,8 @@ pub(crate) fn clean_middle_const<'tcx>(
 ) -> Constant {
     // FIXME: instead of storing the stringified expression, store `self` directly instead.
     Constant {
-        type_: clean_middle_ty(constant.map_bound(|c| c.ty()), cx, None, None),
+        type_: Box::new(clean_middle_ty(constant.map_bound(|c| c.ty()), cx, None, None)),
-        generics: Box::new(Generics::default()),
+        generics: Generics::default(),
         kind: ConstantKind::TyConst { expr: constant.skip_binder().to_string().into() },
     }
 }
@@ -1216,14 +1216,14 @@ fn clean_trait_item<'tcx>(trait_item: &hir::TraitItem<'tcx>, cx: &mut DocContext
             hir::TraitItemKind::Const(ty, Some(default)) => {
                 let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
                 AssocConstItem(
-                    Box::new(generics),
+                    generics,
-                    clean_ty(ty, cx),
+                    Box::new(clean_ty(ty, cx)),
                     ConstantKind::Local { def_id: local_did, body: default },
                 )
             }
             hir::TraitItemKind::Const(ty, None) => {
                 let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
-                TyAssocConstItem(Box::new(generics), clean_ty(ty, cx))
+                TyAssocConstItem(generics, Box::new(clean_ty(ty, cx)))
             }
             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
                 let m = clean_function(cx, sig, trait_item.generics, FunctionArgs::Body(body));
@@ -1272,7 +1272,7 @@ pub(crate) fn clean_impl_item<'tcx>(
             hir::ImplItemKind::Const(ty, expr) => {
                 let generics = clean_generics(impl_.generics, cx);
                 let default = ConstantKind::Local { def_id: local_did, body: expr };
-                AssocConstItem(Box::new(generics), clean_ty(ty, cx), default)
+                AssocConstItem(generics, Box::new(clean_ty(ty, cx)), default)
             }
             hir::ImplItemKind::Fn(ref sig, body) => {
                 let m = clean_function(cx, sig, impl_.generics, FunctionArgs::Body(body));
@@ -1311,18 +1311,18 @@ pub(crate) fn clean_middle_assoc_item<'tcx>(
     let tcx = cx.tcx;
     let kind = match assoc_item.kind {
         ty::AssocKind::Const => {
-            let ty = clean_middle_ty(
+            let ty = Box::new(clean_middle_ty(
                 ty::Binder::dummy(tcx.type_of(assoc_item.def_id).instantiate_identity()),
                 cx,
                 Some(assoc_item.def_id),
                 None,
-            );
+            ));
 
-            let mut generics = Box::new(clean_ty_generics(
+            let mut generics = clean_ty_generics(
                 cx,
                 tcx.generics_of(assoc_item.def_id),
                 tcx.explicit_predicates_of(assoc_item.def_id),
-            ));
+            );
             simplify::move_bounds_to_generic_parameters(&mut generics);
 
             let provided = match assoc_item.container {
@@ -2718,8 +2718,8 @@ fn clean_maybe_renamed_item<'tcx>(
                 StaticItem(Static { type_: clean_ty(ty, cx), mutability, expr: Some(body_id) })
             }
             ItemKind::Const(ty, generics, body_id) => ConstantItem(Constant {
-                type_: clean_ty(ty, cx),
+                type_: Box::new(clean_ty(ty, cx)),
-                generics: Box::new(clean_generics(generics, cx)),
+                generics: clean_generics(generics, cx),
                 kind: ConstantKind::Local { body: body_id, def_id },
             }),
             ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {

src/librustdoc/clean/types.rs

@@ -852,9 +852,9 @@ pub(crate) enum ItemKind {
     ProcMacroItem(ProcMacro),
     PrimitiveItem(PrimitiveType),
     /// A required associated constant in a trait declaration.
-    TyAssocConstItem(Box<Generics>, Type),
+    TyAssocConstItem(Generics, Box<Type>),
     /// An associated constant in a trait impl or a provided one in a trait declaration.
-    AssocConstItem(Box<Generics>, Type, ConstantKind),
+    AssocConstItem(Generics, Box<Type>, ConstantKind),
     /// A required associated type in a trait declaration.
     ///
     /// The bounds may be non-empty if there is a `where` clause.
@@ -2282,8 +2282,8 @@ pub(crate) struct Static {
 
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub(crate) struct Constant {
-    pub(crate) type_: Type,
+    pub(crate) type_: Box<Type>,
-    pub(crate) generics: Box<Generics>,
+    pub(crate) generics: Generics,
     pub(crate) kind: ConstantKind,
 }
 
@@ -2524,8 +2524,7 @@ mod size_asserts {
     static_assert_size!(GenericParamDef, 56);
     static_assert_size!(Generics, 16);
     static_assert_size!(Item, 56);
-    // FIXME(generic_const_items): Further reduce the size.
+    static_assert_size!(ItemKind, 56);
-    static_assert_size!(ItemKind, 72);
     static_assert_size!(PathSegment, 40);
     static_assert_size!(Type, 32);
     // tidy-alphabetical-end

src/librustdoc/json/conversions.rs

@@ -177,7 +177,7 @@ fn from_tcx(constant: clean::Constant, tcx: TyCtxt<'_>) -> Self {
         let expr = constant.expr(tcx);
         let value = constant.value(tcx);
         let is_literal = constant.is_literal(tcx);
-        Constant { type_: constant.type_.into_tcx(tcx), expr, value, is_literal }
+        Constant { type_: (*constant.type_).into_tcx(tcx), expr, value, is_literal }
     }
 }
 
@@ -325,11 +325,11 @@ fn from_clean_item(item: clean::Item, tcx: TyCtxt<'_>) -> ItemEnum {
         }
         // FIXME(generic_const_items): Add support for generic associated consts.
         TyAssocConstItem(_generics, ty) => {
-            ItemEnum::AssocConst { type_: ty.into_tcx(tcx), default: None }
+            ItemEnum::AssocConst { type_: (*ty).into_tcx(tcx), default: None }
         }
         // FIXME(generic_const_items): Add support for generic associated consts.
         AssocConstItem(_generics, ty, default) => {
-            ItemEnum::AssocConst { type_: ty.into_tcx(tcx), default: Some(default.expr(tcx)) }
+            ItemEnum::AssocConst { type_: (*ty).into_tcx(tcx), default: Some(default.expr(tcx)) }
         }
         TyAssocTypeItem(g, b) => ItemEnum::AssocType {
             generics: g.into_tcx(tcx),