crates/hir_def/src/item_tree/lower.rs

   1 //! AST -> `ItemTree` lowering code.
   2
   3 use std::{collections::hash_map::Entry, mem, sync::Arc};
   4
   5 use hir_expand::{ast_id_map::AstIdMap, hygiene::Hygiene, name::known, HirFileId};
   6 use syntax::{
   7     ast::{self, ModuleItemOwner},
   8     SyntaxNode, WalkEvent,
   9 };
  10
  11 use crate::{
  12     generics::{GenericParams, TypeParamData, TypeParamProvenance},
  13     type_ref::{LifetimeRef, TraitRef},
  14 };
  15
  16 use super::*;
  17
  18 fn id<N: ItemTreeNode>(index: Idx<N>) -> FileItemTreeId<N> {
  19     FileItemTreeId { index, _p: PhantomData }
  20 }
  21
  22 pub(super) struct Ctx<'a> {
  23     db: &'a dyn DefDatabase,
  24     tree: ItemTree,
  25     hygiene: Hygiene,
  26     source_ast_id_map: Arc<AstIdMap>,
  27     body_ctx: crate::body::LowerCtx<'a>,
  28     forced_visibility: Option<RawVisibilityId>,
  29 }
  30
  31 impl<'a> Ctx<'a> {
  32     pub(super) fn new(db: &'a dyn DefDatabase, hygiene: Hygiene, file: HirFileId) -> Self {
  33         Self {
  34             db,
  35             tree: ItemTree::default(),
  36             hygiene,
  37             source_ast_id_map: db.ast_id_map(file),
  38             body_ctx: crate::body::LowerCtx::new(db, file),
  39             forced_visibility: None,
  40         }
  41     }
  42
  43     pub(super) fn lower_module_items(mut self, item_owner: &dyn ModuleItemOwner) -> ItemTree {
  44         self.tree.top_level =
  45             item_owner.items().flat_map(|item| self.lower_mod_item(&item, false)).collect();
  46         self.tree
  47     }
  48
  49     pub(super) fn lower_macro_stmts(mut self, stmts: ast::MacroStmts) -> ItemTree {
  50         self.tree.top_level = stmts
  51             .statements()
  52             .filter_map(|stmt| match stmt {
  53                 ast::Stmt::Item(item) => Some(item),
  54                 _ => None,
  55             })
  56             .flat_map(|item| self.lower_mod_item(&item, false))
  57             .collect();
  58
  59         // Non-items need to have their inner items collected.
  60         for stmt in stmts.statements() {
  61             match stmt {
  62                 ast::Stmt::ExprStmt(_) | ast::Stmt::LetStmt(_) => {
  63                     self.collect_inner_items(stmt.syntax())
  64                 }
  65                 _ => {}
  66             }
  67         }
  68         if let Some(expr) = stmts.expr() {
  69             self.collect_inner_items(expr.syntax());
  70         }
  71         self.tree
  72     }
  73
  74     pub(super) fn lower_inner_items(mut self, within: &SyntaxNode) -> ItemTree {
  75         self.collect_inner_items(within);
  76         self.tree
  77     }
  78
  79     fn data(&mut self) -> &mut ItemTreeData {
  80         self.tree.data_mut()
  81     }
  82
  83     fn lower_mod_item(&mut self, item: &ast::Item, inner: bool) -> Option<ModItem> {
  84         // Collect inner items for 1-to-1-lowered items.
  85         match item {
  86             ast::Item::Struct(_)
  87             | ast::Item::Union(_)
  88             | ast::Item::Enum(_)
  89             | ast::Item::Fn(_)
  90             | ast::Item::TypeAlias(_)
  91             | ast::Item::Const(_)
  92             | ast::Item::Static(_) => {
  93                 // Skip this if we're already collecting inner items. We'll descend into all nodes
  94                 // already.
  95                 if !inner {
  96                     self.collect_inner_items(item.syntax());
  97                 }
  98             }
  99
 100             // These are handled in their respective `lower_X` method (since we can't just blindly
 101             // walk them).
 102             ast::Item::Trait(_) | ast::Item::Impl(_) | ast::Item::ExternBlock(_) => {}
 103
 104             // These don't have inner items.
 105             ast::Item::Module(_)
 106             | ast::Item::ExternCrate(_)
 107             | ast::Item::Use(_)
 108             | ast::Item::MacroCall(_)
 109             | ast::Item::MacroRules(_)
 110             | ast::Item::MacroDef(_) => {}
 111         };
 112
 113         let attrs = RawAttrs::new(self.db, item, &self.hygiene);
 114         let item: ModItem = match item {
 115             ast::Item::Struct(ast) => self.lower_struct(ast)?.into(),
 116             ast::Item::Union(ast) => self.lower_union(ast)?.into(),
 117             ast::Item::Enum(ast) => self.lower_enum(ast)?.into(),
 118             ast::Item::Fn(ast) => self.lower_function(ast)?.into(),
 119             ast::Item::TypeAlias(ast) => self.lower_type_alias(ast)?.into(),
 120             ast::Item::Static(ast) => self.lower_static(ast)?.into(),
 121             ast::Item::Const(ast) => self.lower_const(ast).into(),
 122             ast::Item::Module(ast) => self.lower_module(ast)?.into(),
 123             ast::Item::Trait(ast) => self.lower_trait(ast)?.into(),
 124             ast::Item::Impl(ast) => self.lower_impl(ast)?.into(),
 125             ast::Item::Use(ast) => self.lower_use(ast)?.into(),
 126             ast::Item::ExternCrate(ast) => self.lower_extern_crate(ast)?.into(),
 127             ast::Item::MacroCall(ast) => self.lower_macro_call(ast)?.into(),
 128             ast::Item::MacroRules(ast) => self.lower_macro_rules(ast)?.into(),
 129             ast::Item::MacroDef(ast) => self.lower_macro_def(ast)?.into(),
 130             ast::Item::ExternBlock(ast) => self.lower_extern_block(ast).into(),
 131         };
 132
 133         self.add_attrs(item.into(), attrs);
 134
 135         Some(item)
 136     }
 137
 138     fn add_attrs(&mut self, item: AttrOwner, attrs: RawAttrs) {
 139         match self.tree.attrs.entry(item) {
 140             Entry::Occupied(mut entry) => {
 141                 *entry.get_mut() = entry.get().merge(attrs);
 142             }
 143             Entry::Vacant(entry) => {
 144                 entry.insert(attrs);
 145             }
 146         }
 147     }
 148
 149     fn collect_inner_items(&mut self, container: &SyntaxNode) {
 150         let forced_vis = self.forced_visibility.take();
 151
 152         let mut block_stack = Vec::new();
 153
 154         // if container itself is block, add it to the stack
 155         if let Some(block) = ast::BlockExpr::cast(container.clone()) {
 156             block_stack.push(self.source_ast_id_map.ast_id(&block));
 157         }
 158
 159         for event in container.preorder().skip(1) {
 160             match event {
 161                 WalkEvent::Enter(node) => {
 162                     match_ast! {
 163                         match node {
 164                             ast::BlockExpr(block) => {
 165                                 block_stack.push(self.source_ast_id_map.ast_id(&block));
 166                             },
 167                             ast::Item(item) => {
 168                                 // FIXME: This triggers for macro calls in expression/pattern/type position
 169                                 let mod_item = self.lower_mod_item(&item, true);
 170                                 let current_block = block_stack.last();
 171                                 if let (Some(mod_item), Some(block)) = (mod_item, current_block) {
 172                                         self.data().inner_items.entry(*block).or_default().push(mod_item);
 173                                 }
 174                             },
 175                             _ => {}
 176                         }
 177                     }
 178                 }
 179                 WalkEvent::Leave(node) => {
 180                     if ast::BlockExpr::cast(node).is_some() {
 181                         block_stack.pop();
 182                     }
 183                 }
 184             }
 185         }
 186
 187         self.forced_visibility = forced_vis;
 188     }
 189
 190     fn lower_assoc_item(&mut self, item: &ast::AssocItem) -> Option<AssocItem> {
 191         match item {
 192             ast::AssocItem::Fn(ast) => self.lower_function(ast).map(Into::into),
 193             ast::AssocItem::TypeAlias(ast) => self.lower_type_alias(ast).map(Into::into),
 194             ast::AssocItem::Const(ast) => Some(self.lower_const(ast).into()),
 195             ast::AssocItem::MacroCall(ast) => self.lower_macro_call(ast).map(Into::into),
 196         }
 197     }
 198
 199     fn lower_struct(&mut self, strukt: &ast::Struct) -> Option<FileItemTreeId<Struct>> {
 200         let visibility = self.lower_visibility(strukt);
 201         let name = strukt.name()?.as_name();
 202         let generic_params = self.lower_generic_params(GenericsOwner::Struct, strukt);
 203         let fields = self.lower_fields(&strukt.kind());
 204         let ast_id = self.source_ast_id_map.ast_id(strukt);
 205         let res = Struct { name, visibility, generic_params, fields, ast_id };
 206         Some(id(self.data().structs.alloc(res)))
 207     }
 208
 209     fn lower_fields(&mut self, strukt_kind: &ast::StructKind) -> Fields {
 210         match strukt_kind {
 211             ast::StructKind::Record(it) => {
 212                 let range = self.lower_record_fields(it);
 213                 Fields::Record(range)
 214             }
 215             ast::StructKind::Tuple(it) => {
 216                 let range = self.lower_tuple_fields(it);
 217                 Fields::Tuple(range)
 218             }
 219             ast::StructKind::Unit => Fields::Unit,
 220         }
 221     }
 222
 223     fn lower_record_fields(&mut self, fields: &ast::RecordFieldList) -> IdRange<Field> {
 224         let start = self.next_field_idx();
 225         for field in fields.fields() {
 226             if let Some(data) = self.lower_record_field(&field) {
 227                 let idx = self.data().fields.alloc(data);
 228                 self.add_attrs(idx.into(), RawAttrs::new(self.db, &field, &self.hygiene));
 229             }
 230         }
 231         let end = self.next_field_idx();
 232         IdRange::new(start..end)
 233     }
 234
 235     fn lower_record_field(&mut self, field: &ast::RecordField) -> Option<Field> {
 236         let name = field.name()?.as_name();
 237         let visibility = self.lower_visibility(field);
 238         let type_ref = self.lower_type_ref_opt(field.ty());
 239         let res = Field { name, type_ref, visibility };
 240         Some(res)
 241     }
 242
 243     fn lower_tuple_fields(&mut self, fields: &ast::TupleFieldList) -> IdRange<Field> {
 244         let start = self.next_field_idx();
 245         for (i, field) in fields.fields().enumerate() {
 246             let data = self.lower_tuple_field(i, &field);
 247             let idx = self.data().fields.alloc(data);
 248             self.add_attrs(idx.into(), RawAttrs::new(self.db, &field, &self.hygiene));
 249         }
 250         let end = self.next_field_idx();
 251         IdRange::new(start..end)
 252     }
 253
 254     fn lower_tuple_field(&mut self, idx: usize, field: &ast::TupleField) -> Field {
 255         let name = Name::new_tuple_field(idx);
 256         let visibility = self.lower_visibility(field);
 257         let type_ref = self.lower_type_ref_opt(field.ty());
 258         let res = Field { name, type_ref, visibility };
 259         res
 260     }
 261
 262     fn lower_union(&mut self, union: &ast::Union) -> Option<FileItemTreeId<Union>> {
 263         let visibility = self.lower_visibility(union);
 264         let name = union.name()?.as_name();
 265         let generic_params = self.lower_generic_params(GenericsOwner::Union, union);
 266         let fields = match union.record_field_list() {
 267             Some(record_field_list) => self.lower_fields(&StructKind::Record(record_field_list)),
 268             None => Fields::Record(IdRange::new(self.next_field_idx()..self.next_field_idx())),
 269         };
 270         let ast_id = self.source_ast_id_map.ast_id(union);
 271         let res = Union { name, visibility, generic_params, fields, ast_id };
 272         Some(id(self.data().unions.alloc(res)))
 273     }
 274
 275     fn lower_enum(&mut self, enum_: &ast::Enum) -> Option<FileItemTreeId<Enum>> {
 276         let visibility = self.lower_visibility(enum_);
 277         let name = enum_.name()?.as_name();
 278         let generic_params = self.lower_generic_params(GenericsOwner::Enum, enum_);
 279         let variants =
 280             self.with_inherited_visibility(visibility, |this| match &enum_.variant_list() {
 281                 Some(variant_list) => this.lower_variants(variant_list),
 282                 None => IdRange::new(this.next_variant_idx()..this.next_variant_idx()),
 283             });
 284         let ast_id = self.source_ast_id_map.ast_id(enum_);
 285         let res = Enum { name, visibility, generic_params, variants, ast_id };
 286         Some(id(self.data().enums.alloc(res)))
 287     }
 288
 289     fn lower_variants(&mut self, variants: &ast::VariantList) -> IdRange<Variant> {
 290         let start = self.next_variant_idx();
 291         for variant in variants.variants() {
 292             if let Some(data) = self.lower_variant(&variant) {
 293                 let idx = self.data().variants.alloc(data);
 294                 self.add_attrs(idx.into(), RawAttrs::new(self.db, &variant, &self.hygiene));
 295             }
 296         }
 297         let end = self.next_variant_idx();
 298         IdRange::new(start..end)
 299     }
 300
 301     fn lower_variant(&mut self, variant: &ast::Variant) -> Option<Variant> {
 302         let name = variant.name()?.as_name();
 303         let fields = self.lower_fields(&variant.kind());
 304         let res = Variant { name, fields };
 305         Some(res)
 306     }
 307
 308     fn lower_function(&mut self, func: &ast::Fn) -> Option<FileItemTreeId<Function>> {
 309         let visibility = self.lower_visibility(func);
 310         let name = func.name()?.as_name();
 311
 312         let mut has_self_param = false;
 313         let start_param = self.next_param_idx();
 314         if let Some(param_list) = func.param_list() {
 315             if let Some(self_param) = param_list.self_param() {
 316                 let self_type = match self_param.ty() {
 317                     Some(type_ref) => TypeRef::from_ast(&self.body_ctx, type_ref),
 318                     None => {
 319                         let self_type = TypeRef::Path(name![Self].into());
 320                         match self_param.kind() {
 321                             ast::SelfParamKind::Owned => self_type,
 322                             ast::SelfParamKind::Ref => TypeRef::Reference(
 323                                 Box::new(self_type),
 324                                 self_param.lifetime().as_ref().map(LifetimeRef::new),
 325                                 Mutability::Shared,
 326                             ),
 327                             ast::SelfParamKind::MutRef => TypeRef::Reference(
 328                                 Box::new(self_type),
 329                                 self_param.lifetime().as_ref().map(LifetimeRef::new),
 330                                 Mutability::Mut,
 331                             ),
 332                         }
 333                     }
 334                 };
 335                 let ty = Interned::new(self_type);
 336                 let idx = self.data().params.alloc(Param::Normal(ty));
 337                 self.add_attrs(idx.into(), RawAttrs::new(self.db, &self_param, &self.hygiene));
 338                 has_self_param = true;
 339             }
 340             for param in param_list.params() {
 341                 let idx = match param.dotdotdot_token() {
 342                     Some(_) => self.data().params.alloc(Param::Varargs),
 343                     None => {
 344                         let type_ref = TypeRef::from_ast_opt(&self.body_ctx, param.ty());
 345                         let ty = Interned::new(type_ref);
 346                         self.data().params.alloc(Param::Normal(ty))
 347                     }
 348                 };
 349                 self.add_attrs(idx.into(), RawAttrs::new(self.db, &param, &self.hygiene));
 350             }
 351         }
 352         let end_param = self.next_param_idx();
 353         let params = IdRange::new(start_param..end_param);
 354
 355         let ret_type = match func.ret_type().and_then(|rt| rt.ty()) {
 356             Some(type_ref) => TypeRef::from_ast(&self.body_ctx, type_ref),
 357             _ => TypeRef::unit(),
 358         };
 359
 360         let (ret_type, async_ret_type) = if func.async_token().is_some() {
 361             let async_ret_type = ret_type.clone();
 362             let future_impl = desugar_future_path(ret_type);
 363             let ty_bound = Interned::new(TypeBound::Path(future_impl));
 364             (TypeRef::ImplTrait(vec![ty_bound]), Some(async_ret_type))
 365         } else {
 366             (ret_type, None)
 367         };
 368
 369         let abi = func.abi().map(lower_abi);
 370
 371         let ast_id = self.source_ast_id_map.ast_id(func);
 372
 373         let mut flags = FnFlags::default();
 374         if func.body().is_some() {
 375             flags.bits |= FnFlags::HAS_BODY;
 376         }
 377         if has_self_param {
 378             flags.bits |= FnFlags::HAS_SELF_PARAM;
 379         }
 380         if func.default_token().is_some() {
 381             flags.bits |= FnFlags::IS_DEFAULT;
 382         }
 383         if func.const_token().is_some() {
 384             flags.bits |= FnFlags::IS_CONST;
 385         }
 386         if func.async_token().is_some() {
 387             flags.bits |= FnFlags::IS_ASYNC;
 388         }
 389         if func.unsafe_token().is_some() {
 390             flags.bits |= FnFlags::IS_UNSAFE;
 391         }
 392
 393         let mut res = Function {
 394             name,
 395             visibility,
 396             generic_params: Interned::new(GenericParams::default()),
 397             abi,
 398             params,
 399             ret_type: Interned::new(ret_type),
 400             async_ret_type: async_ret_type.map(Interned::new),
 401             ast_id,
 402             flags,
 403         };
 404         res.generic_params = self.lower_generic_params(GenericsOwner::Function(&res), func);
 405
 406         Some(id(self.data().functions.alloc(res)))
 407     }
 408
 409     fn lower_type_alias(
 410         &mut self,
 411         type_alias: &ast::TypeAlias,
 412     ) -> Option<FileItemTreeId<TypeAlias>> {
 413         let name = type_alias.name()?.as_name();
 414         let type_ref = type_alias.ty().map(|it| self.lower_type_ref(&it));
 415         let visibility = self.lower_visibility(type_alias);
 416         let bounds = self.lower_type_bounds(type_alias);
 417         let generic_params = self.lower_generic_params(GenericsOwner::TypeAlias, type_alias);
 418         let ast_id = self.source_ast_id_map.ast_id(type_alias);
 419         let res = TypeAlias {
 420             name,
 421             visibility,
 422             bounds: bounds.into_boxed_slice(),
 423             generic_params,
 424             type_ref,
 425             ast_id,
 426             is_extern: false,
 427         };
 428         Some(id(self.data().type_aliases.alloc(res)))
 429     }
 430
 431     fn lower_static(&mut self, static_: &ast::Static) -> Option<FileItemTreeId<Static>> {
 432         let name = static_.name()?.as_name();
 433         let type_ref = self.lower_type_ref_opt(static_.ty());
 434         let visibility = self.lower_visibility(static_);
 435         let mutable = static_.mut_token().is_some();
 436         let ast_id = self.source_ast_id_map.ast_id(static_);
 437         let res = Static { name, visibility, mutable, type_ref, ast_id, is_extern: false };
 438         Some(id(self.data().statics.alloc(res)))
 439     }
 440
 441     fn lower_const(&mut self, konst: &ast::Const) -> FileItemTreeId<Const> {
 442         let name = konst.name().map(|it| it.as_name());
 443         let type_ref = self.lower_type_ref_opt(konst.ty());
 444         let visibility = self.lower_visibility(konst);
 445         let ast_id = self.source_ast_id_map.ast_id(konst);
 446         let res = Const { name, visibility, type_ref, ast_id };
 447         id(self.data().consts.alloc(res))
 448     }
 449
 450     fn lower_module(&mut self, module: &ast::Module) -> Option<FileItemTreeId<Mod>> {
 451         let name = module.name()?.as_name();
 452         let visibility = self.lower_visibility(module);
 453         let kind = if module.semicolon_token().is_some() {
 454             ModKind::Outline {}
 455         } else {
 456             ModKind::Inline {
 457                 items: module
 458                     .item_list()
 459                     .map(|list| {
 460                         list.items().flat_map(|item| self.lower_mod_item(&item, false)).collect()
 461                     })
 462                     .unwrap_or_else(|| {
 463                         cov_mark::hit!(name_res_works_for_broken_modules);
 464                         Box::new([]) as Box<[_]>
 465                     }),
 466             }
 467         };
 468         let ast_id = self.source_ast_id_map.ast_id(module);
 469         let res = Mod { name, visibility, kind, ast_id };
 470         Some(id(self.data().mods.alloc(res)))
 471     }
 472
 473     fn lower_trait(&mut self, trait_def: &ast::Trait) -> Option<FileItemTreeId<Trait>> {
 474         let name = trait_def.name()?.as_name();
 475         let visibility = self.lower_visibility(trait_def);
 476         let generic_params =
 477             self.lower_generic_params_and_inner_items(GenericsOwner::Trait(trait_def), trait_def);
 478         let is_auto = trait_def.auto_token().is_some();
 479         let is_unsafe = trait_def.unsafe_token().is_some();
 480         let items = trait_def.assoc_item_list().map(|list| {
 481             let db = self.db;
 482             self.with_inherited_visibility(visibility, |this| {
 483                 list.assoc_items()
 484                     .filter_map(|item| {
 485                         let attrs = RawAttrs::new(db, &item, &this.hygiene);
 486                         this.collect_inner_items(item.syntax());
 487                         this.lower_assoc_item(&item).map(|item| {
 488                             this.add_attrs(ModItem::from(item).into(), attrs);
 489                             item
 490                         })
 491                     })
 492                     .collect()
 493             })
 494         });
 495         let ast_id = self.source_ast_id_map.ast_id(trait_def);
 496         let res = Trait {
 497             name,
 498             visibility,
 499             generic_params,
 500             is_auto,
 501             is_unsafe,
 502             items: items.unwrap_or_default(),
 503             ast_id,
 504         };
 505         Some(id(self.data().traits.alloc(res)))
 506     }
 507
 508     fn lower_impl(&mut self, impl_def: &ast::Impl) -> Option<FileItemTreeId<Impl>> {
 509         let generic_params =
 510             self.lower_generic_params_and_inner_items(GenericsOwner::Impl, impl_def);
 511         // FIXME: If trait lowering fails, due to a non PathType for example, we treat this impl
 512         // as if it was an non-trait impl. Ideally we want to create a unique missing ref that only
 513         // equals itself.
 514         let target_trait = impl_def.trait_().and_then(|tr| self.lower_trait_ref(&tr));
 515         let self_ty = self.lower_type_ref(&impl_def.self_ty()?);
 516         let is_negative = impl_def.excl_token().is_some();
 517
 518         // We cannot use `assoc_items()` here as that does not include macro calls.
 519         let items = impl_def
 520             .assoc_item_list()
 521             .into_iter()
 522             .flat_map(|it| it.assoc_items())
 523             .filter_map(|item| {
 524                 self.collect_inner_items(item.syntax());
 525                 let assoc = self.lower_assoc_item(&item)?;
 526                 let attrs = RawAttrs::new(self.db, &item, &self.hygiene);
 527                 self.add_attrs(ModItem::from(assoc).into(), attrs);
 528                 Some(assoc)
 529             })
 530             .collect();
 531         let ast_id = self.source_ast_id_map.ast_id(impl_def);
 532         let res = Impl { generic_params, target_trait, self_ty, is_negative, items, ast_id };
 533         Some(id(self.data().impls.alloc(res)))
 534     }
 535
 536     fn lower_use(&mut self, use_item: &ast::Use) -> Option<FileItemTreeId<Import>> {
 537         let visibility = self.lower_visibility(use_item);
 538         let ast_id = self.source_ast_id_map.ast_id(use_item);
 539         let (use_tree, _) = lower_use_tree(self.db, &self.hygiene, use_item.use_tree()?)?;
 540
 541         let res = Import { visibility, ast_id, use_tree };
 542         Some(id(self.data().imports.alloc(res)))
 543     }
 544
 545     fn lower_extern_crate(
 546         &mut self,
 547         extern_crate: &ast::ExternCrate,
 548     ) -> Option<FileItemTreeId<ExternCrate>> {
 549         let name = extern_crate.name_ref()?.as_name();
 550         let alias = extern_crate.rename().map(|a| {
 551             a.name().map(|it| it.as_name()).map_or(ImportAlias::Underscore, ImportAlias::Alias)
 552         });
 553         let visibility = self.lower_visibility(extern_crate);
 554         let ast_id = self.source_ast_id_map.ast_id(extern_crate);
 555
 556         let res = ExternCrate { name, alias, visibility, ast_id };
 557         Some(id(self.data().extern_crates.alloc(res)))
 558     }
 559
 560     fn lower_macro_call(&mut self, m: &ast::MacroCall) -> Option<FileItemTreeId<MacroCall>> {
 561         let path = Interned::new(ModPath::from_src(self.db, m.path()?, &self.hygiene)?);
 562         let ast_id = self.source_ast_id_map.ast_id(m);
 563         let fragment = hir_expand::to_fragment_kind(m);
 564         let res = MacroCall { path, ast_id, fragment };
 565         Some(id(self.data().macro_calls.alloc(res)))
 566     }
 567
 568     fn lower_macro_rules(&mut self, m: &ast::MacroRules) -> Option<FileItemTreeId<MacroRules>> {
 569         let name = m.name().map(|it| it.as_name())?;
 570         let ast_id = self.source_ast_id_map.ast_id(m);
 571
 572         let res = MacroRules { name, ast_id };
 573         Some(id(self.data().macro_rules.alloc(res)))
 574     }
 575
 576     fn lower_macro_def(&mut self, m: &ast::MacroDef) -> Option<FileItemTreeId<MacroDef>> {
 577         let name = m.name().map(|it| it.as_name())?;
 578
 579         let ast_id = self.source_ast_id_map.ast_id(m);
 580         let visibility = self.lower_visibility(m);
 581
 582         let res = MacroDef { name, ast_id, visibility };
 583         Some(id(self.data().macro_defs.alloc(res)))
 584     }
 585
 586     fn lower_extern_block(&mut self, block: &ast::ExternBlock) -> FileItemTreeId<ExternBlock> {
 587         let ast_id = self.source_ast_id_map.ast_id(block);
 588         let abi = block.abi().map(lower_abi);
 589         let children: Box<[_]> = block.extern_item_list().map_or(Box::new([]), |list| {
 590             list.extern_items()
 591                 .filter_map(|item| {
 592                     self.collect_inner_items(item.syntax());
 593                     let attrs = RawAttrs::new(self.db, &item, &self.hygiene);
 594                     let id: ModItem = match item {
 595                         ast::ExternItem::Fn(ast) => {
 596                             let func_id = self.lower_function(&ast)?;
 597                             let func = &mut self.data().functions[func_id.index];
 598                             if is_intrinsic_fn_unsafe(&func.name) {
 599                                 func.flags.bits |= FnFlags::IS_UNSAFE;
 600                             }
 601                             func.flags.bits |= FnFlags::IS_IN_EXTERN_BLOCK;
 602                             func_id.into()
 603                         }
 604                         ast::ExternItem::Static(ast) => {
 605                             let statik = self.lower_static(&ast)?;
 606                             self.data().statics[statik.index].is_extern = true;
 607                             statik.into()
 608                         }
 609                         ast::ExternItem::TypeAlias(ty) => {
 610                             let foreign_ty = self.lower_type_alias(&ty)?;
 611                             self.data().type_aliases[foreign_ty.index].is_extern = true;
 612                             foreign_ty.into()
 613                         }
 614                         ast::ExternItem::MacroCall(call) => {
 615                             // FIXME: we need some way of tracking that the macro call is in an
 616                             // extern block
 617                             self.lower_macro_call(&call)?.into()
 618                         }
 619                     };
 620                     self.add_attrs(id.into(), attrs);
 621                     Some(id)
 622                 })
 623                 .collect()
 624         });
 625
 626         let res = ExternBlock { abi, ast_id, children };
 627         id(self.data().extern_blocks.alloc(res))
 628     }
 629
 630     /// Lowers generics defined on `node` and collects inner items defined within.
 631     fn lower_generic_params_and_inner_items(
 632         &mut self,
 633         owner: GenericsOwner<'_>,
 634         node: &impl ast::GenericParamsOwner,
 635     ) -> Interned<GenericParams> {
 636         // Generics are part of item headers and may contain inner items we need to collect.
 637         if let Some(params) = node.generic_param_list() {
 638             self.collect_inner_items(params.syntax());
 639         }
 640         if let Some(clause) = node.where_clause() {
 641             self.collect_inner_items(clause.syntax());
 642         }
 643
 644         self.lower_generic_params(owner, node)
 645     }
 646
 647     fn lower_generic_params(
 648         &mut self,
 649         owner: GenericsOwner<'_>,
 650         node: &impl ast::GenericParamsOwner,
 651     ) -> Interned<GenericParams> {
 652         let mut sm = &mut Default::default();
 653         let mut generics = GenericParams::default();
 654         match owner {
 655             GenericsOwner::Function(func) => {
 656                 generics.fill(&self.body_ctx, sm, node);
 657                 // lower `impl Trait` in arguments
 658                 for id in func.params.clone() {
 659                     if let Param::Normal(ty) = &self.data().params[id] {
 660                         generics.fill_implicit_impl_trait_args(ty);
 661                     }
 662                 }
 663             }
 664             GenericsOwner::Struct
 665             | GenericsOwner::Enum
 666             | GenericsOwner::Union
 667             | GenericsOwner::TypeAlias => {
 668                 generics.fill(&self.body_ctx, sm, node);
 669             }
 670             GenericsOwner::Trait(trait_def) => {
 671                 // traits get the Self type as an implicit first type parameter
 672                 let self_param_id = generics.types.alloc(TypeParamData {
 673                     name: Some(name![Self]),
 674                     default: None,
 675                     provenance: TypeParamProvenance::TraitSelf,
 676                 });
 677                 sm.type_params.insert(self_param_id, Either::Right(trait_def.clone()));
 678                 // add super traits as bounds on Self
 679                 // i.e., trait Foo: Bar is equivalent to trait Foo where Self: Bar
 680                 let self_param = TypeRef::Path(name![Self].into());
 681                 generics.fill_bounds(&self.body_ctx, trait_def, Either::Left(self_param));
 682                 generics.fill(&self.body_ctx, &mut sm, node);
 683             }
 684             GenericsOwner::Impl => {
 685                 // Note that we don't add `Self` here: in `impl`s, `Self` is not a
 686                 // type-parameter, but rather is a type-alias for impl's target
 687                 // type, so this is handled by the resolver.
 688                 generics.fill(&self.body_ctx, &mut sm, node);
 689             }
 690         }
 691
 692         generics.shrink_to_fit();
 693         Interned::new(generics)
 694     }
 695
 696     fn lower_type_bounds(&mut self, node: &impl ast::TypeBoundsOwner) -> Vec<Interned<TypeBound>> {
 697         match node.type_bound_list() {
 698             Some(bound_list) => bound_list
 699                 .bounds()
 700                 .map(|it| Interned::new(TypeBound::from_ast(&self.body_ctx, it)))
 701                 .collect(),
 702             None => Vec::new(),
 703         }
 704     }
 705
 706     fn lower_visibility(&mut self, item: &impl ast::VisibilityOwner) -> RawVisibilityId {
 707         let vis = match self.forced_visibility {
 708             Some(vis) => return vis,
 709             None => RawVisibility::from_ast_with_hygiene(self.db, item.visibility(), &self.hygiene),
 710         };
 711
 712         self.data().vis.alloc(vis)
 713     }
 714
 715     fn lower_trait_ref(&mut self, trait_ref: &ast::Type) -> Option<Interned<TraitRef>> {
 716         let trait_ref = TraitRef::from_ast(&self.body_ctx, trait_ref.clone())?;
 717         Some(Interned::new(trait_ref))
 718     }
 719
 720     fn lower_type_ref(&mut self, type_ref: &ast::Type) -> Interned<TypeRef> {
 721         let tyref = TypeRef::from_ast(&self.body_ctx, type_ref.clone());
 722         Interned::new(tyref)
 723     }
 724
 725     fn lower_type_ref_opt(&mut self, type_ref: Option<ast::Type>) -> Interned<TypeRef> {
 726         match type_ref.map(|ty| self.lower_type_ref(&ty)) {
 727             Some(it) => it,
 728             None => Interned::new(TypeRef::Error),
 729         }
 730     }
 731
 732     /// Forces the visibility `vis` to be used for all items lowered during execution of `f`.
 733     fn with_inherited_visibility<R>(
 734         &mut self,
 735         vis: RawVisibilityId,
 736         f: impl FnOnce(&mut Self) -> R,
 737     ) -> R {
 738         let old = mem::replace(&mut self.forced_visibility, Some(vis));
 739         let res = f(self);
 740         self.forced_visibility = old;
 741         res
 742     }
 743
 744     fn next_field_idx(&self) -> Idx<Field> {
 745         Idx::from_raw(RawIdx::from(
 746             self.tree.data.as_ref().map_or(0, |data| data.fields.len() as u32),
 747         ))
 748     }
 749     fn next_variant_idx(&self) -> Idx<Variant> {
 750         Idx::from_raw(RawIdx::from(
 751             self.tree.data.as_ref().map_or(0, |data| data.variants.len() as u32),
 752         ))
 753     }
 754     fn next_param_idx(&self) -> Idx<Param> {
 755         Idx::from_raw(RawIdx::from(
 756             self.tree.data.as_ref().map_or(0, |data| data.params.len() as u32),
 757         ))
 758     }
 759 }
 760
 761 fn desugar_future_path(orig: TypeRef) -> Path {
 762     let path = path![core::future::Future];
 763     let mut generic_args: Vec<_> =
 764         std::iter::repeat(None).take(path.segments().len() - 1).collect();
 765     let mut last = GenericArgs::empty();
 766     let binding =
 767         AssociatedTypeBinding { name: name![Output], type_ref: Some(orig), bounds: Vec::new() };
 768     last.bindings.push(binding);
 769     generic_args.push(Some(Interned::new(last)));
 770
 771     Path::from_known_path(path, generic_args)
 772 }
 773
 774 enum GenericsOwner<'a> {
 775     /// We need access to the partially-lowered `Function` for lowering `impl Trait` in argument
 776     /// position.
 777     Function(&'a Function),
 778     Struct,
 779     Enum,
 780     Union,
 781     /// The `TraitDef` is needed to fill the source map for the implicit `Self` parameter.
 782     Trait(&'a ast::Trait),
 783     TypeAlias,
 784     Impl,
 785 }
 786
 787 /// Returns `true` if the given intrinsic is unsafe to call, or false otherwise.
 788 fn is_intrinsic_fn_unsafe(name: &Name) -> bool {
 789     // Should be kept in sync with https://github.com/rust-lang/rust/blob/c6e4db620a7d2f569f11dcab627430921ea8aacf/compiler/rustc_typeck/src/check/intrinsic.rs#L68
 790     ![
 791         known::abort,
 792         known::min_align_of,
 793         known::needs_drop,
 794         known::caller_location,
 795         known::size_of_val,
 796         known::min_align_of_val,
 797         known::add_with_overflow,
 798         known::sub_with_overflow,
 799         known::mul_with_overflow,
 800         known::wrapping_add,
 801         known::wrapping_sub,
 802         known::wrapping_mul,
 803         known::saturating_add,
 804         known::saturating_sub,
 805         known::rotate_left,
 806         known::rotate_right,
 807         known::ctpop,
 808         known::ctlz,
 809         known::cttz,
 810         known::bswap,
 811         known::bitreverse,
 812         known::discriminant_value,
 813         known::type_id,
 814         known::likely,
 815         known::unlikely,
 816         known::ptr_guaranteed_eq,
 817         known::ptr_guaranteed_ne,
 818         known::minnumf32,
 819         known::minnumf64,
 820         known::maxnumf32,
 821         known::rustc_peek,
 822         known::maxnumf64,
 823         known::type_name,
 824         known::variant_count,
 825     ]
 826     .contains(name)
 827 }
 828
 829 fn lower_abi(abi: ast::Abi) -> Interned<str> {
 830     // FIXME: Abi::abi() -> Option<SyntaxToken>?
 831     match abi.syntax().last_token() {
 832         Some(tok) if tok.kind() == SyntaxKind::STRING => {
 833             // FIXME: Better way to unescape?
 834             Interned::new_str(tok.text().trim_matches('"'))
 835         }
 836         _ => {
 837             // `extern` default to be `extern "C"`.
 838             Interned::new_str("C")
 839         }
 840     }
 841 }
 842
 843 struct UseTreeLowering<'a> {
 844     db: &'a dyn DefDatabase,
 845     hygiene: &'a Hygiene,
 846     mapping: Arena<ast::UseTree>,
 847 }
 848
 849 impl UseTreeLowering<'_> {
 850     fn lower_use_tree(&mut self, tree: ast::UseTree) -> Option<UseTree> {
 851         if let Some(use_tree_list) = tree.use_tree_list() {
 852             let prefix = match tree.path() {
 853                 // E.g. use something::{{{inner}}};
 854                 None => None,
 855                 // E.g. `use something::{inner}` (prefix is `None`, path is `something`)
 856                 // or `use something::{path::{inner::{innerer}}}` (prefix is `something::path`, path is `inner`)
 857                 Some(path) => {
 858                     match ModPath::from_src(self.db, path, self.hygiene) {
 859                         Some(it) => Some(it),
 860                         None => return None, // FIXME: report errors somewhere
 861                     }
 862                 }
 863             };
 864
 865             let list =
 866                 use_tree_list.use_trees().filter_map(|tree| self.lower_use_tree(tree)).collect();
 867
 868             Some(
 869                 self.use_tree(
 870                     UseTreeKind::Prefixed { prefix: prefix.map(Interned::new), list },
 871                     tree,
 872                 ),
 873             )
 874         } else {
 875             let is_glob = tree.star_token().is_some();
 876             let path = match tree.path() {
 877                 Some(path) => Some(ModPath::from_src(self.db, path, self.hygiene)?),
 878                 None => None,
 879             };
 880             let alias = tree.rename().map(|a| {
 881                 a.name().map(|it| it.as_name()).map_or(ImportAlias::Underscore, ImportAlias::Alias)
 882             });
 883             if alias.is_some() && is_glob {
 884                 return None;
 885             }
 886
 887             match (path, alias, is_glob) {
 888                 (path, None, true) => {
 889                     if path.is_none() {
 890                         cov_mark::hit!(glob_enum_group);
 891                     }
 892                     Some(self.use_tree(UseTreeKind::Glob { path: path.map(Interned::new) }, tree))
 893                 }
 894                 // Globs can't be renamed
 895                 (_, Some(_), true) | (None, None, false) => None,
 896                 // `bla::{ as Name}` is invalid
 897                 (None, Some(_), false) => None,
 898                 (Some(path), alias, false) => Some(
 899                     self.use_tree(UseTreeKind::Single { path: Interned::new(path), alias }, tree),
 900                 ),
 901             }
 902         }
 903     }
 904
 905     fn use_tree(&mut self, kind: UseTreeKind, ast: ast::UseTree) -> UseTree {
 906         let index = self.mapping.alloc(ast);
 907         UseTree { index, kind }
 908     }
 909 }
 910
 911 pub(super) fn lower_use_tree(
 912     db: &dyn DefDatabase,
 913     hygiene: &Hygiene,
 914     tree: ast::UseTree,
 915 ) -> Option<(UseTree, Arena<ast::UseTree>)> {
 916     let mut lowering = UseTreeLowering { db, hygiene, mapping: Arena::new() };
 917     let tree = lowering.lower_use_tree(tree)?;
 918     Some((tree, lowering.mapping))
 919 }