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