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