Auto merge of rust-lang#118947 - Bryanskiy:delegStep1, r=petrochenkov…

…,lcnr

Delegation implementation: step 1

See rust-lang#118212 for more details.

r? `@petrochenkov`

compiler/rustc_ast/src/ast.rs

@@ -2873,6 +2873,7 @@ impl Item {
  | ItemKind::ForeignMod(_)
  | ItemKind::GlobalAsm(_)
  | ItemKind::MacCall(_)
+ | ItemKind::Delegation(_)
  | ItemKind::MacroDef(_) => None,
  ItemKind::Static(_) => None,
  ItemKind::Const(i) => Some(&i.generics),
@@ -3019,6 +3020,15 @@ pub struct Fn {
  pub body: Option<P<Block>>,
 }
 
+#[derive(Clone, Encodable, Decodable, Debug)]
+pub struct Delegation {
+ /// Path resolution id.
+ pub id: NodeId,
+ pub qself: Option<P<QSelf>>,
+ pub path: Path,
+ pub body: Option<P<Block>>,
+}
+
 #[derive(Clone, Encodable, Decodable, Debug)]
 pub struct StaticItem {
  pub ty: P<Ty>,
@@ -3104,14 +3114,20 @@ pub enum ItemKind {
 
  /// A macro definition.
  MacroDef(MacroDef),
+
+ /// A delegation item (`reuse`).
+ ///
+ /// E.g. `reuse <Type as Trait>::name { target_expr_template }`.
+ Delegation(Box<Delegation>),
 }
 
 impl ItemKind {
  pub fn article(&self) -> &'static str {
  use ItemKind::*;
  match self {
  Use(..) | Static(..) | Const(..) | Fn(..) | Mod(..) | GlobalAsm(..) | TyAlias(..)
- | Struct(..) | Union(..) | Trait(..) | TraitAlias(..) | MacroDef(..) => "a",
+ | Struct(..) | Union(..) | Trait(..) | TraitAlias(..) | MacroDef(..)
+ | Delegation(..) => "a",
  ExternCrate(..) | ForeignMod(..) | MacCall(..) | Enum(..) | Impl { .. } => "an",
  }
  }
@@ -3135,6 +3151,7 @@ impl ItemKind {
  ItemKind::MacCall(..) => "item macro invocation",
  ItemKind::MacroDef(..) => "macro definition",
  ItemKind::Impl { .. } => "implementation",
+ ItemKind::Delegation(..) => "delegated function",
  }
  }
 
@@ -3176,6 +3193,8 @@ pub enum AssocItemKind {
  Type(Box<TyAlias>),
  /// A macro expanding to associated items.
  MacCall(P<MacCall>),
+ /// An associated delegation item.
+ Delegation(Box<Delegation>),
 }
 
 impl AssocItemKind {
@@ -3184,7 +3203,7 @@ impl AssocItemKind {
  Self::Const(box ConstItem { defaultness, .. })
  | Self::Fn(box Fn { defaultness, .. })
  | Self::Type(box TyAlias { defaultness, .. }) => defaultness,
- Self::MacCall(..) => Defaultness::Final,
+ Self::MacCall(..) | Self::Delegation(..) => Defaultness::Final,
  }
  }
 }
@@ -3196,6 +3215,7 @@ impl From<AssocItemKind> for ItemKind {
  AssocItemKind::Fn(fn_kind) => ItemKind::Fn(fn_kind),
  AssocItemKind::Type(ty_alias_kind) => ItemKind::TyAlias(ty_alias_kind),
  AssocItemKind::MacCall(a) => ItemKind::MacCall(a),
+ AssocItemKind::Delegation(delegation) => ItemKind::Delegation(delegation),
  }
  }
 }
@@ -3209,6 +3229,7 @@ impl TryFrom<ItemKind> for AssocItemKind {
  ItemKind::Fn(fn_kind) => AssocItemKind::Fn(fn_kind),
  ItemKind::TyAlias(ty_kind) => AssocItemKind::Type(ty_kind),
  ItemKind::MacCall(a) => AssocItemKind::MacCall(a),
+ ItemKind::Delegation(d) => AssocItemKind::Delegation(d),
  _ => return Err(item_kind),
  })
  }

compiler/rustc_ast/src/mut_visit.rs

@@ -1117,6 +1117,14 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
  }
  ItemKind::MacCall(m) => vis.visit_mac_call(m),
  ItemKind::MacroDef(def) => vis.visit_macro_def(def),
+ ItemKind::Delegation(box Delegation { id, qself, path, body }) => {
+ vis.visit_id(id);
+ vis.visit_qself(qself);
+ vis.visit_path(path);
+ if let Some(body) = body {
+ vis.visit_block(body);
+ }
+ }
  }
 }
 
@@ -1155,6 +1163,14 @@ pub fn noop_flat_map_assoc_item<T: MutVisitor>(
  visit_opt(ty, |ty| visitor.visit_ty(ty));
  }
  AssocItemKind::MacCall(mac) => visitor.visit_mac_call(mac),
+ AssocItemKind::Delegation(box Delegation { id, qself, path, body }) => {
+ visitor.visit_id(id);
+ visitor.visit_qself(qself);
+ visitor.visit_path(path);
+ if let Some(body) = body {
+ visitor.visit_block(body);
+ }
+ }
  }
  visitor.visit_span(span);
  visit_lazy_tts(tokens, visitor);

compiler/rustc_ast/src/visit.rs

@@ -375,6 +375,15 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
  }
  ItemKind::MacCall(mac) => visitor.visit_mac_call(mac),
  ItemKind::MacroDef(ts) => visitor.visit_mac_def(ts, item.id),
+ ItemKind::Delegation(box Delegation { id: _, qself, path, body }) => {
+ if let Some(qself) = qself {
+ visitor.visit_ty(&qself.ty);
+ }
+ walk_path(visitor, path);
+ if let Some(body) = body {
+ visitor.visit_block(body);
+ }
+ }
  }
  walk_list!(visitor, visit_attribute, &item.attrs);
 }
@@ -704,6 +713,15 @@ pub fn walk_assoc_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem,
  AssocItemKind::MacCall(mac) => {
  visitor.visit_mac_call(mac);
  }
+ AssocItemKind::Delegation(box Delegation { id: _, qself, path, body }) => {
+ if let Some(qself) = qself {
+ visitor.visit_ty(&qself.ty);
+ }
+ walk_path(visitor, path);
+ if let Some(body) = body {
+ visitor.visit_block(body);
+ }
+ }
  }
 }