crates/hir/src/source_analyzer.rs

   1 //! Lookup hir elements using positions in the source code. This is a lossy
   2 //! transformation: in general, a single source might correspond to several
   3 //! modules, functions, etc, due to macros, cfgs and `#[path=]` attributes on
   4 //! modules.
   5 //!
   6 //! So, this modules should not be used during hir construction, it exists
   7 //! purely for "IDE needs".
   8 use std::{iter::once, sync::Arc};
   9
  10 use hir_def::{
  11     body::{
  12         self,
  13         scope::{ExprScopes, ScopeId},
  14         Body, BodySourceMap,
  15     },
  16     expr::{ExprId, Pat, PatId},
  17     path::{ModPath, Path, PathKind},
  18     resolver::{resolver_for_scope, Resolver, TypeNs, ValueNs},
  19     AsMacroCall, DefWithBodyId, FieldId, FunctionId, LocalFieldId, ModuleDefId, VariantId,
  20 };
  21 use hir_expand::{hygiene::Hygiene, name::AsName, HirFileId, InFile};
  22 use hir_ty::{
  23     diagnostics::{record_literal_missing_fields, record_pattern_missing_fields},
  24     InferenceResult, Interner, Substitution, TyExt, TyLoweringContext,
  25 };
  26 use syntax::{
  27     ast::{self, AstNode},
  28     SyntaxNode, TextRange, TextSize,
  29 };
  30
  31 use crate::{
  32     db::HirDatabase, semantics::PathResolution, Adt, BuiltinAttr, BuiltinType, Const, Field,
  33     Function, Local, MacroDef, ModuleDef, Static, Struct, ToolModule, Trait, Type, TypeAlias,
  34     TypeParam, Variant,
  35 };
  36 use base_db::CrateId;
  37
  38 /// `SourceAnalyzer` is a convenience wrapper which exposes HIR API in terms of
  39 /// original source files. It should not be used inside the HIR itself.
  40 #[derive(Debug)]
  41 pub(crate) struct SourceAnalyzer {
  42     pub(crate) file_id: HirFileId,
  43     pub(crate) resolver: Resolver,
  44     body: Option<Arc<Body>>,
  45     body_source_map: Option<Arc<BodySourceMap>>,
  46     infer: Option<Arc<InferenceResult>>,
  47 }
  48
  49 impl SourceAnalyzer {
  50     pub(crate) fn new_for_body(
  51         db: &dyn HirDatabase,
  52         def: DefWithBodyId,
  53         node @ InFile { file_id, .. }: InFile<&SyntaxNode>,
  54         offset: Option<TextSize>,
  55     ) -> SourceAnalyzer {
  56         let (body, source_map) = db.body_with_source_map(def);
  57         let scopes = db.expr_scopes(def);
  58         let scope = match offset {
  59             None => scope_for(&scopes, &source_map, node),
  60             Some(offset) => scope_for_offset(db, &scopes, &source_map, node.with_value(offset)),
  61         };
  62         let resolver = resolver_for_scope(db.upcast(), def, scope);
  63         SourceAnalyzer {
  64             resolver,
  65             body: Some(body),
  66             body_source_map: Some(source_map),
  67             infer: Some(db.infer(def)),
  68             file_id,
  69         }
  70     }
  71
  72     pub(crate) fn new_for_body_no_infer(
  73         db: &dyn HirDatabase,
  74         def: DefWithBodyId,
  75         node @ InFile { file_id, .. }: InFile<&SyntaxNode>,
  76         offset: Option<TextSize>,
  77     ) -> SourceAnalyzer {
  78         let (body, source_map) = db.body_with_source_map(def);
  79         let scopes = db.expr_scopes(def);
  80         let scope = match offset {
  81             None => scope_for(&scopes, &source_map, node),
  82             Some(offset) => scope_for_offset(db, &scopes, &source_map, node.with_value(offset)),
  83         };
  84         let resolver = resolver_for_scope(db.upcast(), def, scope);
  85         SourceAnalyzer {
  86             resolver,
  87             body: Some(body),
  88             body_source_map: Some(source_map),
  89             infer: None,
  90             file_id,
  91         }
  92     }
  93
  94     pub(crate) fn new_for_resolver(
  95         resolver: Resolver,
  96         node: InFile<&SyntaxNode>,
  97     ) -> SourceAnalyzer {
  98         SourceAnalyzer {
  99             resolver,
 100             body: None,
 101             body_source_map: None,
 102             infer: None,
 103             file_id: node.file_id,
 104         }
 105     }
 106
 107     fn expr_id(&self, db: &dyn HirDatabase, expr: &ast::Expr) -> Option<ExprId> {
 108         let src = match expr {
 109             ast::Expr::MacroCall(call) => {
 110                 self.expand_expr(db, InFile::new(self.file_id, call.clone()))?
 111             }
 112             _ => InFile::new(self.file_id, expr.clone()),
 113         };
 114         let sm = self.body_source_map.as_ref()?;
 115         sm.node_expr(src.as_ref())
 116     }
 117
 118     fn pat_id(&self, pat: &ast::Pat) -> Option<PatId> {
 119         // FIXME: macros, see `expr_id`
 120         let src = InFile { file_id: self.file_id, value: pat };
 121         self.body_source_map.as_ref()?.node_pat(src)
 122     }
 123
 124     fn expand_expr(
 125         &self,
 126         db: &dyn HirDatabase,
 127         expr: InFile<ast::MacroCall>,
 128     ) -> Option<InFile<ast::Expr>> {
 129         let macro_file = self.body_source_map.as_ref()?.node_macro_file(expr.as_ref())?;
 130         let expanded = db.parse_or_expand(macro_file)?;
 131
 132         let res = match ast::MacroCall::cast(expanded.clone()) {
 133             Some(call) => self.expand_expr(db, InFile::new(macro_file, call))?,
 134             _ => InFile::new(macro_file, ast::Expr::cast(expanded)?),
 135         };
 136         Some(res)
 137     }
 138
 139     pub(crate) fn type_of_expr(
 140         &self,
 141         db: &dyn HirDatabase,
 142         expr: &ast::Expr,
 143     ) -> Option<(Type, Option<Type>)> {
 144         let expr_id = self.expr_id(db, expr)?;
 145         let infer = self.infer.as_ref()?;
 146         let coerced = infer
 147             .expr_adjustments
 148             .get(&expr_id)
 149             .and_then(|adjusts| adjusts.last().map(|adjust| adjust.target.clone()));
 150         let ty = infer[expr_id].clone();
 151         let mk_ty = |ty| Type::new_with_resolver(db, &self.resolver, ty);
 152         mk_ty(ty).zip(Some(coerced.and_then(mk_ty)))
 153     }
 154
 155     pub(crate) fn type_of_pat(
 156         &self,
 157         db: &dyn HirDatabase,
 158         pat: &ast::Pat,
 159     ) -> Option<(Type, Option<Type>)> {
 160         let pat_id = self.pat_id(pat)?;
 161         let infer = self.infer.as_ref()?;
 162         let coerced = infer
 163             .pat_adjustments
 164             .get(&pat_id)
 165             .and_then(|adjusts| adjusts.last().map(|adjust| adjust.target.clone()));
 166         let ty = infer[pat_id].clone();
 167         let mk_ty = |ty| Type::new_with_resolver(db, &self.resolver, ty);
 168         mk_ty(ty).zip(Some(coerced.and_then(mk_ty)))
 169     }
 170
 171     pub(crate) fn type_of_self(
 172         &self,
 173         db: &dyn HirDatabase,
 174         param: &ast::SelfParam,
 175     ) -> Option<Type> {
 176         let src = InFile { file_id: self.file_id, value: param };
 177         let pat_id = self.body_source_map.as_ref()?.node_self_param(src)?;
 178         let ty = self.infer.as_ref()?[pat_id].clone();
 179         Type::new_with_resolver(db, &self.resolver, ty)
 180     }
 181
 182     pub(crate) fn resolve_method_call(
 183         &self,
 184         db: &dyn HirDatabase,
 185         call: &ast::MethodCallExpr,
 186     ) -> Option<(FunctionId, Substitution)> {
 187         let expr_id = self.expr_id(db, &call.clone().into())?;
 188         self.infer.as_ref()?.method_resolution(expr_id)
 189     }
 190
 191     pub(crate) fn resolve_field(
 192         &self,
 193         db: &dyn HirDatabase,
 194         field: &ast::FieldExpr,
 195     ) -> Option<Field> {
 196         let expr_id = self.expr_id(db, &field.clone().into())?;
 197         self.infer.as_ref()?.field_resolution(expr_id).map(|it| it.into())
 198     }
 199
 200     pub(crate) fn resolve_record_field(
 201         &self,
 202         db: &dyn HirDatabase,
 203         field: &ast::RecordExprField,
 204     ) -> Option<(Field, Option<Local>, Type)> {
 205         let record_expr = ast::RecordExpr::cast(field.syntax().parent().and_then(|p| p.parent())?)?;
 206         let expr = ast::Expr::from(record_expr);
 207         let expr_id = self.body_source_map.as_ref()?.node_expr(InFile::new(self.file_id, &expr))?;
 208
 209         let local_name = field.field_name()?.as_name();
 210         let local = if field.name_ref().is_some() {
 211             None
 212         } else {
 213             let path = ModPath::from_segments(PathKind::Plain, once(local_name.clone()));
 214             match self.resolver.resolve_path_in_value_ns_fully(db.upcast(), &path) {
 215                 Some(ValueNs::LocalBinding(pat_id)) => {
 216                     Some(Local { pat_id, parent: self.resolver.body_owner()? })
 217                 }
 218                 _ => None,
 219             }
 220         };
 221         let (_, subst) = self.infer.as_ref()?.type_of_expr.get(expr_id)?.as_adt()?;
 222         let variant = self.infer.as_ref()?.variant_resolution_for_expr(expr_id)?;
 223         let variant_data = variant.variant_data(db.upcast());
 224         let field = FieldId { parent: variant, local_id: variant_data.field(&local_name)? };
 225         let field_ty =
 226             db.field_types(variant).get(field.local_id)?.clone().substitute(Interner, subst);
 227         Some((field.into(), local, Type::new_with_resolver(db, &self.resolver, field_ty)?))
 228     }
 229
 230     pub(crate) fn resolve_record_pat_field(
 231         &self,
 232         db: &dyn HirDatabase,
 233         field: &ast::RecordPatField,
 234     ) -> Option<Field> {
 235         let field_name = field.field_name()?.as_name();
 236         let record_pat = ast::RecordPat::cast(field.syntax().parent().and_then(|p| p.parent())?)?;
 237         let pat_id = self.pat_id(&record_pat.into())?;
 238         let variant = self.infer.as_ref()?.variant_resolution_for_pat(pat_id)?;
 239         let variant_data = variant.variant_data(db.upcast());
 240         let field = FieldId { parent: variant, local_id: variant_data.field(&field_name)? };
 241         Some(field.into())
 242     }
 243
 244     pub(crate) fn resolve_macro_call(
 245         &self,
 246         db: &dyn HirDatabase,
 247         macro_call: InFile<&ast::MacroCall>,
 248     ) -> Option<MacroDef> {
 249         let ctx = body::LowerCtx::new(db.upcast(), macro_call.file_id);
 250         let path = macro_call.value.path().and_then(|ast| Path::from_src(ast, &ctx))?;
 251         self.resolver.resolve_path_as_macro(db.upcast(), path.mod_path()).map(|it| it.into())
 252     }
 253
 254     pub(crate) fn resolve_bind_pat_to_const(
 255         &self,
 256         db: &dyn HirDatabase,
 257         pat: &ast::IdentPat,
 258     ) -> Option<ModuleDef> {
 259         let pat_id = self.pat_id(&pat.clone().into())?;
 260         let body = self.body.as_ref()?;
 261         let path = match &body[pat_id] {
 262             Pat::Path(path) => path,
 263             _ => return None,
 264         };
 265         let res = resolve_hir_path(db, &self.resolver, path)?;
 266         match res {
 267             PathResolution::Def(def) => Some(def),
 268             _ => None,
 269         }
 270     }
 271
 272     pub(crate) fn resolve_path(
 273         &self,
 274         db: &dyn HirDatabase,
 275         path: &ast::Path,
 276     ) -> Option<PathResolution> {
 277         let parent = path.syntax().parent();
 278         let parent = || parent.clone();
 279
 280         let mut prefer_value_ns = false;
 281         if let Some(path_expr) = parent().and_then(ast::PathExpr::cast) {
 282             let expr_id = self.expr_id(db, &path_expr.into())?;
 283             let infer = self.infer.as_ref()?;
 284             if let Some(assoc) = infer.assoc_resolutions_for_expr(expr_id) {
 285                 return Some(PathResolution::AssocItem(assoc.into()));
 286             }
 287             if let Some(VariantId::EnumVariantId(variant)) =
 288                 infer.variant_resolution_for_expr(expr_id)
 289             {
 290                 return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
 291             }
 292             prefer_value_ns = true;
 293         }
 294
 295         if let Some(path_pat) = parent().and_then(ast::PathPat::cast) {
 296             let pat_id = self.pat_id(&path_pat.into())?;
 297             if let Some(assoc) = self.infer.as_ref()?.assoc_resolutions_for_pat(pat_id) {
 298                 return Some(PathResolution::AssocItem(assoc.into()));
 299             }
 300             if let Some(VariantId::EnumVariantId(variant)) =
 301                 self.infer.as_ref()?.variant_resolution_for_pat(pat_id)
 302             {
 303                 return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
 304             }
 305         }
 306
 307         if let Some(rec_lit) = parent().and_then(ast::RecordExpr::cast) {
 308             let expr_id = self.expr_id(db, &rec_lit.into())?;
 309             if let Some(VariantId::EnumVariantId(variant)) =
 310                 self.infer.as_ref()?.variant_resolution_for_expr(expr_id)
 311             {
 312                 return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
 313             }
 314         }
 315
 316         let record_pat = parent().and_then(ast::RecordPat::cast).map(ast::Pat::from);
 317         let tuple_struct_pat = || parent().and_then(ast::TupleStructPat::cast).map(ast::Pat::from);
 318         if let Some(pat) = record_pat.or_else(tuple_struct_pat) {
 319             let pat_id = self.pat_id(&pat)?;
 320             let variant_res_for_pat = self.infer.as_ref()?.variant_resolution_for_pat(pat_id);
 321             if let Some(VariantId::EnumVariantId(variant)) = variant_res_for_pat {
 322                 return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
 323             }
 324         }
 325
 326         // This must be a normal source file rather than macro file.
 327         let hygiene = Hygiene::new(db.upcast(), self.file_id);
 328         let ctx = body::LowerCtx::with_hygiene(db.upcast(), &hygiene);
 329         let hir_path = Path::from_src(path.clone(), &ctx)?;
 330
 331         // Case where path is a qualifier of a use tree, e.g. foo::bar::{Baz, Qux} where we are
 332         // trying to resolve foo::bar.
 333         if let Some(use_tree) = parent().and_then(ast::UseTree::cast) {
 334             if let Some(qualifier) = use_tree.path() {
 335                 if path == &qualifier && use_tree.coloncolon_token().is_some() {
 336                     return resolve_hir_path_qualifier(db, &self.resolver, &hir_path);
 337                 }
 338             }
 339         }
 340
 341         let is_path_of_attr = path
 342             .top_path()
 343             .syntax()
 344             .ancestors()
 345             .nth(2) // Path -> Meta -> Attr
 346             .map_or(false, |it| ast::Attr::can_cast(it.kind()));
 347
 348         // Case where path is a qualifier of another path, e.g. foo::bar::Baz where we are
 349         // trying to resolve foo::bar.
 350         if let Some(outer_path) = path.parent_path() {
 351             if let Some(qualifier) = outer_path.qualifier() {
 352                 if path == &qualifier {
 353                     return resolve_hir_path_qualifier(db, &self.resolver, &hir_path);
 354                 }
 355             }
 356         } else if is_path_of_attr {
 357             // Case where we are resolving the final path segment of a path in an attribute
 358             // in this case we have to check for inert/builtin attributes and tools and prioritize
 359             // resolution of attributes over other namesapces
 360             let name_ref = path.as_single_name_ref();
 361             let builtin =
 362                 name_ref.as_ref().map(ast::NameRef::text).as_deref().and_then(BuiltinAttr::by_name);
 363             if let builtin @ Some(_) = builtin {
 364                 return builtin.map(PathResolution::BuiltinAttr);
 365             }
 366             return match resolve_hir_path_as_macro(db, &self.resolver, &hir_path) {
 367                 res @ Some(m) if m.is_attr() => res.map(PathResolution::Macro),
 368                 _ => name_ref.and_then(|name_ref| {
 369                     ToolModule::by_name(&name_ref.text()).map(PathResolution::ToolModule)
 370                 }),
 371             };
 372         }
 373
 374         let res = if parent().map_or(false, |it| ast::Visibility::can_cast(it.kind())) {
 375             resolve_hir_path_qualifier(db, &self.resolver, &hir_path)
 376         } else {
 377             resolve_hir_path_(db, &self.resolver, &hir_path, prefer_value_ns)
 378         };
 379         match res {
 380             Some(_) => res,
 381             // this labels any path that starts with a tool module as the tool itself, this is technically wrong
 382             // but there is no benefit in differentiating these two cases for the time being
 383             None if is_path_of_attr => path
 384                 .first_segment()
 385                 .and_then(|seg| seg.name_ref())
 386                 .and_then(|name_ref| ToolModule::by_name(&name_ref.text()))
 387                 .map(PathResolution::ToolModule),
 388             None => None,
 389         }
 390     }
 391
 392     pub(crate) fn record_literal_missing_fields(
 393         &self,
 394         db: &dyn HirDatabase,
 395         literal: &ast::RecordExpr,
 396     ) -> Option<Vec<(Field, Type)>> {
 397         let krate = self.resolver.krate()?;
 398         let body = self.body.as_ref()?;
 399         let infer = self.infer.as_ref()?;
 400
 401         let expr_id = self.expr_id(db, &literal.clone().into())?;
 402         let substs = infer.type_of_expr[expr_id].as_adt()?.1;
 403
 404         let (variant, missing_fields, _exhaustive) =
 405             record_literal_missing_fields(db, infer, expr_id, &body[expr_id])?;
 406         let res = self.missing_fields(db, krate, substs, variant, missing_fields);
 407         Some(res)
 408     }
 409
 410     pub(crate) fn record_pattern_missing_fields(
 411         &self,
 412         db: &dyn HirDatabase,
 413         pattern: &ast::RecordPat,
 414     ) -> Option<Vec<(Field, Type)>> {
 415         let krate = self.resolver.krate()?;
 416         let body = self.body.as_ref()?;
 417         let infer = self.infer.as_ref()?;
 418
 419         let pat_id = self.pat_id(&pattern.clone().into())?;
 420         let substs = infer.type_of_pat[pat_id].as_adt()?.1;
 421
 422         let (variant, missing_fields, _exhaustive) =
 423             record_pattern_missing_fields(db, infer, pat_id, &body[pat_id])?;
 424         let res = self.missing_fields(db, krate, substs, variant, missing_fields);
 425         Some(res)
 426     }
 427
 428     fn missing_fields(
 429         &self,
 430         db: &dyn HirDatabase,
 431         krate: CrateId,
 432         substs: &Substitution,
 433         variant: VariantId,
 434         missing_fields: Vec<LocalFieldId>,
 435     ) -> Vec<(Field, Type)> {
 436         let field_types = db.field_types(variant);
 437
 438         missing_fields
 439             .into_iter()
 440             .map(|local_id| {
 441                 let field = FieldId { parent: variant, local_id };
 442                 let ty = field_types[local_id].clone().substitute(Interner, substs);
 443                 (field.into(), Type::new_with_resolver_inner(db, krate, &self.resolver, ty))
 444             })
 445             .collect()
 446     }
 447
 448     pub(crate) fn expand(
 449         &self,
 450         db: &dyn HirDatabase,
 451         macro_call: InFile<&ast::MacroCall>,
 452     ) -> Option<HirFileId> {
 453         let krate = self.resolver.krate()?;
 454         let macro_call_id = macro_call.as_call_id(db.upcast(), krate, |path| {
 455             self.resolver.resolve_path_as_macro(db.upcast(), &path)
 456         })?;
 457         Some(macro_call_id.as_file()).filter(|it| it.expansion_level(db.upcast()) < 64)
 458     }
 459
 460     pub(crate) fn resolve_variant(
 461         &self,
 462         db: &dyn HirDatabase,
 463         record_lit: ast::RecordExpr,
 464     ) -> Option<VariantId> {
 465         let infer = self.infer.as_ref()?;
 466         let expr_id = self.expr_id(db, &record_lit.into())?;
 467         infer.variant_resolution_for_expr(expr_id)
 468     }
 469 }
 470
 471 fn scope_for(
 472     scopes: &ExprScopes,
 473     source_map: &BodySourceMap,
 474     node: InFile<&SyntaxNode>,
 475 ) -> Option<ScopeId> {
 476     node.value
 477         .ancestors()
 478         .filter_map(ast::Expr::cast)
 479         .filter_map(|it| source_map.node_expr(InFile::new(node.file_id, &it)))
 480         .find_map(|it| scopes.scope_for(it))
 481 }
 482
 483 fn scope_for_offset(
 484     db: &dyn HirDatabase,
 485     scopes: &ExprScopes,
 486     source_map: &BodySourceMap,
 487     offset: InFile<TextSize>,
 488 ) -> Option<ScopeId> {
 489     scopes
 490         .scope_by_expr()
 491         .iter()
 492         .filter_map(|(id, scope)| {
 493             let source = source_map.expr_syntax(*id).ok()?;
 494             // FIXME: correctly handle macro expansion
 495             if source.file_id != offset.file_id {
 496                 return None;
 497             }
 498             let root = source.file_syntax(db.upcast());
 499             let node = source.value.to_node(&root);
 500             Some((node.syntax().text_range(), scope))
 501         })
 502         // find containing scope
 503         .min_by_key(|(expr_range, _scope)| {
 504             (
 505                 !(expr_range.start() <= offset.value && offset.value <= expr_range.end()),
 506                 expr_range.len(),
 507             )
 508         })
 509         .map(|(expr_range, scope)| {
 510             adjust(db, scopes, source_map, expr_range, offset).unwrap_or(*scope)
 511         })
 512 }
 513
 514 // XXX: during completion, cursor might be outside of any particular
 515 // expression. Try to figure out the correct scope...
 516 fn adjust(
 517     db: &dyn HirDatabase,
 518     scopes: &ExprScopes,
 519     source_map: &BodySourceMap,
 520     expr_range: TextRange,
 521     offset: InFile<TextSize>,
 522 ) -> Option<ScopeId> {
 523     let child_scopes = scopes
 524         .scope_by_expr()
 525         .iter()
 526         .filter_map(|(id, scope)| {
 527             let source = source_map.expr_syntax(*id).ok()?;
 528             // FIXME: correctly handle macro expansion
 529             if source.file_id != offset.file_id {
 530                 return None;
 531             }
 532             let root = source.file_syntax(db.upcast());
 533             let node = source.value.to_node(&root);
 534             Some((node.syntax().text_range(), scope))
 535         })
 536         .filter(|&(range, _)| {
 537             range.start() <= offset.value && expr_range.contains_range(range) && range != expr_range
 538         });
 539
 540     child_scopes
 541         .max_by(|&(r1, _), &(r2, _)| {
 542             if r1.contains_range(r2) {
 543                 std::cmp::Ordering::Greater
 544             } else if r2.contains_range(r1) {
 545                 std::cmp::Ordering::Less
 546             } else {
 547                 r1.start().cmp(&r2.start())
 548             }
 549         })
 550         .map(|(_ptr, scope)| *scope)
 551 }
 552
 553 #[inline]
 554 pub(crate) fn resolve_hir_path(
 555     db: &dyn HirDatabase,
 556     resolver: &Resolver,
 557     path: &Path,
 558 ) -> Option<PathResolution> {
 559     resolve_hir_path_(db, resolver, path, false)
 560 }
 561
 562 #[inline]
 563 pub(crate) fn resolve_hir_path_as_macro(
 564     db: &dyn HirDatabase,
 565     resolver: &Resolver,
 566     path: &Path,
 567 ) -> Option<MacroDef> {
 568     resolver.resolve_path_as_macro(db.upcast(), path.mod_path()).map(Into::into)
 569 }
 570
 571 fn resolve_hir_path_(
 572     db: &dyn HirDatabase,
 573     resolver: &Resolver,
 574     path: &Path,
 575     prefer_value_ns: bool,
 576 ) -> Option<PathResolution> {
 577     let types = || {
 578         let (ty, unresolved) = match path.type_anchor() {
 579             Some(type_ref) => {
 580                 let (_, res) = TyLoweringContext::new(db, resolver).lower_ty_ext(type_ref);
 581                 res.map(|ty_ns| (ty_ns, path.segments().first()))
 582             }
 583             None => {
 584                 let (ty, remaining) =
 585                     resolver.resolve_path_in_type_ns(db.upcast(), path.mod_path())?;
 586                 match remaining {
 587                     Some(remaining) if remaining > 1 => None,
 588                     _ => Some((ty, path.segments().get(1))),
 589                 }
 590             }
 591         }?;
 592
 593         // If we are in a TypeNs for a Trait, and we have an unresolved name, try to resolve it as a type
 594         // within the trait's associated types.
 595         if let (Some(unresolved), &TypeNs::TraitId(trait_id)) = (&unresolved, &ty) {
 596             if let Some(type_alias_id) =
 597                 db.trait_data(trait_id).associated_type_by_name(&unresolved.name)
 598             {
 599                 return Some(PathResolution::Def(ModuleDefId::from(type_alias_id).into()));
 600             }
 601         }
 602
 603         let res = match ty {
 604             TypeNs::SelfType(it) => PathResolution::SelfType(it.into()),
 605             TypeNs::GenericParam(id) => PathResolution::TypeParam(TypeParam { id }),
 606             TypeNs::AdtSelfType(it) | TypeNs::AdtId(it) => {
 607                 PathResolution::Def(Adt::from(it).into())
 608             }
 609             TypeNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
 610             TypeNs::TypeAliasId(it) => PathResolution::Def(TypeAlias::from(it).into()),
 611             TypeNs::BuiltinType(it) => PathResolution::Def(BuiltinType::from(it).into()),
 612             TypeNs::TraitId(it) => PathResolution::Def(Trait::from(it).into()),
 613         };
 614         match unresolved {
 615             Some(unresolved) => res
 616                 .assoc_type_shorthand_candidates(db, |name, alias| {
 617                     (name == unresolved.name).then(|| alias)
 618                 })
 619                 .map(TypeAlias::from)
 620                 .map(Into::into)
 621                 .map(PathResolution::Def),
 622             None => Some(res),
 623         }
 624     };
 625
 626     let body_owner = resolver.body_owner();
 627     let values = || {
 628         resolver.resolve_path_in_value_ns_fully(db.upcast(), path.mod_path()).and_then(|val| {
 629             let res = match val {
 630                 ValueNs::LocalBinding(pat_id) => {
 631                     let var = Local { parent: body_owner?, pat_id };
 632                     PathResolution::Local(var)
 633                 }
 634                 ValueNs::FunctionId(it) => PathResolution::Def(Function::from(it).into()),
 635                 ValueNs::ConstId(it) => PathResolution::Def(Const::from(it).into()),
 636                 ValueNs::StaticId(it) => PathResolution::Def(Static::from(it).into()),
 637                 ValueNs::StructId(it) => PathResolution::Def(Struct::from(it).into()),
 638                 ValueNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
 639                 ValueNs::ImplSelf(impl_id) => PathResolution::SelfType(impl_id.into()),
 640                 ValueNs::GenericParam(it) => PathResolution::ConstParam(it.into()),
 641             };
 642             Some(res)
 643         })
 644     };
 645
 646     let items = || {
 647         resolver
 648             .resolve_module_path_in_items(db.upcast(), path.mod_path())
 649             .take_types()
 650             .map(|it| PathResolution::Def(it.into()))
 651     };
 652
 653     let macros = || {
 654         resolver
 655             .resolve_path_as_macro(db.upcast(), path.mod_path())
 656             .map(|def| PathResolution::Macro(def.into()))
 657     };
 658
 659     if prefer_value_ns { values().or_else(types) } else { types().or_else(values) }
 660         .or_else(items)
 661         .or_else(macros)
 662 }
 663
 664 /// Resolves a path where we know it is a qualifier of another path.
 665 ///
 666 /// For example, if we have:
 667 /// ```
 668 /// mod my {
 669 ///     pub mod foo {
 670 ///         struct Bar;
 671 ///     }
 672 ///
 673 ///     pub fn foo() {}
 674 /// }
 675 /// ```
 676 /// then we know that `foo` in `my::foo::Bar` refers to the module, not the function.
 677 fn resolve_hir_path_qualifier(
 678     db: &dyn HirDatabase,
 679     resolver: &Resolver,
 680     path: &Path,
 681 ) -> Option<PathResolution> {
 682     let items = resolver
 683         .resolve_module_path_in_items(db.upcast(), path.mod_path())
 684         .take_types()
 685         .map(|it| PathResolution::Def(it.into()));
 686
 687     if items.is_some() {
 688         return items;
 689     }
 690
 691     resolver.resolve_path_in_type_ns_fully(db.upcast(), path.mod_path()).map(|ty| match ty {
 692         TypeNs::SelfType(it) => PathResolution::SelfType(it.into()),
 693         TypeNs::GenericParam(id) => PathResolution::TypeParam(TypeParam { id }),
 694         TypeNs::AdtSelfType(it) | TypeNs::AdtId(it) => PathResolution::Def(Adt::from(it).into()),
 695         TypeNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
 696         TypeNs::TypeAliasId(it) => PathResolution::Def(TypeAlias::from(it).into()),
 697         TypeNs::BuiltinType(it) => PathResolution::Def(BuiltinType::from(it).into()),
 698         TypeNs::TraitId(it) => PathResolution::Def(Trait::from(it).into()),
 699     })
 700 }