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