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         } else if let Some(path_pat) = parent().and_then(ast::PathPat::cast) {
 294             let pat_id = self.pat_id(&path_pat.into())?;
 295             if let Some(assoc) = self.infer.as_ref()?.assoc_resolutions_for_pat(pat_id) {
 296                 return Some(PathResolution::AssocItem(assoc.into()));
 297             }
 298             if let Some(VariantId::EnumVariantId(variant)) =
 299                 self.infer.as_ref()?.variant_resolution_for_pat(pat_id)
 300             {
 301                 return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
 302             }
 303         } else if let Some(rec_lit) = parent().and_then(ast::RecordExpr::cast) {
 304             let expr_id = self.expr_id(db, &rec_lit.into())?;
 305             if let Some(VariantId::EnumVariantId(variant)) =
 306                 self.infer.as_ref()?.variant_resolution_for_expr(expr_id)
 307             {
 308                 return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
 309             }
 310         }
 311
 312         let record_pat = parent().and_then(ast::RecordPat::cast).map(ast::Pat::from);
 313         let tuple_struct_pat = || parent().and_then(ast::TupleStructPat::cast).map(ast::Pat::from);
 314         if let Some(pat) = record_pat.or_else(tuple_struct_pat) {
 315             let pat_id = self.pat_id(&pat)?;
 316             let variant_res_for_pat = self.infer.as_ref()?.variant_resolution_for_pat(pat_id);
 317             if let Some(VariantId::EnumVariantId(variant)) = variant_res_for_pat {
 318                 return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
 319             }
 320         }
 321
 322         // This must be a normal source file rather than macro file.
 323         let hygiene = Hygiene::new(db.upcast(), self.file_id);
 324         let ctx = body::LowerCtx::with_hygiene(db.upcast(), &hygiene);
 325         let hir_path = Path::from_src(path.clone(), &ctx)?;
 326
 327         // Case where path is a qualifier of a use tree, e.g. foo::bar::{Baz, Qux} where we are
 328         // trying to resolve foo::bar.
 329         if let Some(use_tree) = parent().and_then(ast::UseTree::cast) {
 330             if use_tree.coloncolon_token().is_some() {
 331                 return resolve_hir_path_qualifier(db, &self.resolver, &hir_path);
 332             }
 333         }
 334
 335         let is_path_of_attr = path
 336             .syntax()
 337             .ancestors()
 338             .map(|it| it.kind())
 339             .take_while(|&kind| ast::Path::can_cast(kind) || ast::Meta::can_cast(kind))
 340             .last()
 341             .map_or(false, ast::Meta::can_cast);
 342
 343         // Case where path is a qualifier of another path, e.g. foo::bar::Baz where we are
 344         // trying to resolve foo::bar.
 345         if path.parent_path().is_some() {
 346             return match resolve_hir_path_qualifier(db, &self.resolver, &hir_path) {
 347                 None if is_path_of_attr => {
 348                     path.first_segment().and_then(|it| it.name_ref()).and_then(|name_ref| {
 349                         ToolModule::by_name(&name_ref.text()).map(PathResolution::ToolModule)
 350                     })
 351                 }
 352                 res => res,
 353             };
 354         } else if is_path_of_attr {
 355             // Case where we are resolving the final path segment of a path in an attribute
 356             // in this case we have to check for inert/builtin attributes and tools and prioritize
 357             // resolution of attributes over other namespaces
 358             let name_ref = path.as_single_name_ref();
 359             let builtin =
 360                 name_ref.as_ref().map(ast::NameRef::text).as_deref().and_then(BuiltinAttr::by_name);
 361             if let builtin @ Some(_) = builtin {
 362                 return builtin.map(PathResolution::BuiltinAttr);
 363             }
 364             return match resolve_hir_path_as_macro(db, &self.resolver, &hir_path) {
 365                 res @ Some(m) if m.is_attr() => res.map(PathResolution::Macro),
 366                 // this labels any path that starts with a tool module as the tool itself, this is technically wrong
 367                 // but there is no benefit in differentiating these two cases for the time being
 368                 _ => path.first_segment().and_then(|it| it.name_ref()).and_then(|name_ref| {
 369                     ToolModule::by_name(&name_ref.text()).map(PathResolution::ToolModule)
 370                 }),
 371             };
 372         }
 373         if parent().map_or(false, |it| ast::Visibility::can_cast(it.kind())) {
 374             resolve_hir_path_qualifier(db, &self.resolver, &hir_path)
 375         } else {
 376             resolve_hir_path_(db, &self.resolver, &hir_path, prefer_value_ns)
 377         }
 378     }
 379
 380     pub(crate) fn record_literal_missing_fields(
 381         &self,
 382         db: &dyn HirDatabase,
 383         literal: &ast::RecordExpr,
 384     ) -> Option<Vec<(Field, Type)>> {
 385         let krate = self.resolver.krate()?;
 386         let body = self.body.as_ref()?;
 387         let infer = self.infer.as_ref()?;
 388
 389         let expr_id = self.expr_id(db, &literal.clone().into())?;
 390         let substs = infer.type_of_expr[expr_id].as_adt()?.1;
 391
 392         let (variant, missing_fields, _exhaustive) =
 393             record_literal_missing_fields(db, infer, expr_id, &body[expr_id])?;
 394         let res = self.missing_fields(db, krate, substs, variant, missing_fields);
 395         Some(res)
 396     }
 397
 398     pub(crate) fn record_pattern_missing_fields(
 399         &self,
 400         db: &dyn HirDatabase,
 401         pattern: &ast::RecordPat,
 402     ) -> Option<Vec<(Field, Type)>> {
 403         let krate = self.resolver.krate()?;
 404         let body = self.body.as_ref()?;
 405         let infer = self.infer.as_ref()?;
 406
 407         let pat_id = self.pat_id(&pattern.clone().into())?;
 408         let substs = infer.type_of_pat[pat_id].as_adt()?.1;
 409
 410         let (variant, missing_fields, _exhaustive) =
 411             record_pattern_missing_fields(db, infer, pat_id, &body[pat_id])?;
 412         let res = self.missing_fields(db, krate, substs, variant, missing_fields);
 413         Some(res)
 414     }
 415
 416     fn missing_fields(
 417         &self,
 418         db: &dyn HirDatabase,
 419         krate: CrateId,
 420         substs: &Substitution,
 421         variant: VariantId,
 422         missing_fields: Vec<LocalFieldId>,
 423     ) -> Vec<(Field, Type)> {
 424         let field_types = db.field_types(variant);
 425
 426         missing_fields
 427             .into_iter()
 428             .map(|local_id| {
 429                 let field = FieldId { parent: variant, local_id };
 430                 let ty = field_types[local_id].clone().substitute(Interner, substs);
 431                 (field.into(), Type::new_with_resolver_inner(db, krate, &self.resolver, ty))
 432             })
 433             .collect()
 434     }
 435
 436     pub(crate) fn expand(
 437         &self,
 438         db: &dyn HirDatabase,
 439         macro_call: InFile<&ast::MacroCall>,
 440     ) -> Option<HirFileId> {
 441         let krate = self.resolver.krate()?;
 442         let macro_call_id = macro_call.as_call_id(db.upcast(), krate, |path| {
 443             self.resolver.resolve_path_as_macro(db.upcast(), &path)
 444         })?;
 445         Some(macro_call_id.as_file()).filter(|it| it.expansion_level(db.upcast()) < 64)
 446     }
 447
 448     pub(crate) fn resolve_variant(
 449         &self,
 450         db: &dyn HirDatabase,
 451         record_lit: ast::RecordExpr,
 452     ) -> Option<VariantId> {
 453         let infer = self.infer.as_ref()?;
 454         let expr_id = self.expr_id(db, &record_lit.into())?;
 455         infer.variant_resolution_for_expr(expr_id)
 456     }
 457 }
 458
 459 fn scope_for(
 460     scopes: &ExprScopes,
 461     source_map: &BodySourceMap,
 462     node: InFile<&SyntaxNode>,
 463 ) -> Option<ScopeId> {
 464     node.value
 465         .ancestors()
 466         .filter_map(ast::Expr::cast)
 467         .filter_map(|it| source_map.node_expr(InFile::new(node.file_id, &it)))
 468         .find_map(|it| scopes.scope_for(it))
 469 }
 470
 471 fn scope_for_offset(
 472     db: &dyn HirDatabase,
 473     scopes: &ExprScopes,
 474     source_map: &BodySourceMap,
 475     offset: InFile<TextSize>,
 476 ) -> Option<ScopeId> {
 477     scopes
 478         .scope_by_expr()
 479         .iter()
 480         .filter_map(|(id, scope)| {
 481             let source = source_map.expr_syntax(*id).ok()?;
 482             // FIXME: correctly handle macro expansion
 483             if source.file_id != offset.file_id {
 484                 return None;
 485             }
 486             let root = source.file_syntax(db.upcast());
 487             let node = source.value.to_node(&root);
 488             Some((node.syntax().text_range(), scope))
 489         })
 490         // find containing scope
 491         .min_by_key(|(expr_range, _scope)| {
 492             (
 493                 !(expr_range.start() <= offset.value && offset.value <= expr_range.end()),
 494                 expr_range.len(),
 495             )
 496         })
 497         .map(|(expr_range, scope)| {
 498             adjust(db, scopes, source_map, expr_range, offset).unwrap_or(*scope)
 499         })
 500 }
 501
 502 // XXX: during completion, cursor might be outside of any particular
 503 // expression. Try to figure out the correct scope...
 504 fn adjust(
 505     db: &dyn HirDatabase,
 506     scopes: &ExprScopes,
 507     source_map: &BodySourceMap,
 508     expr_range: TextRange,
 509     offset: InFile<TextSize>,
 510 ) -> Option<ScopeId> {
 511     let child_scopes = scopes
 512         .scope_by_expr()
 513         .iter()
 514         .filter_map(|(id, scope)| {
 515             let source = source_map.expr_syntax(*id).ok()?;
 516             // FIXME: correctly handle macro expansion
 517             if source.file_id != offset.file_id {
 518                 return None;
 519             }
 520             let root = source.file_syntax(db.upcast());
 521             let node = source.value.to_node(&root);
 522             Some((node.syntax().text_range(), scope))
 523         })
 524         .filter(|&(range, _)| {
 525             range.start() <= offset.value && expr_range.contains_range(range) && range != expr_range
 526         });
 527
 528     child_scopes
 529         .max_by(|&(r1, _), &(r2, _)| {
 530             if r1.contains_range(r2) {
 531                 std::cmp::Ordering::Greater
 532             } else if r2.contains_range(r1) {
 533                 std::cmp::Ordering::Less
 534             } else {
 535                 r1.start().cmp(&r2.start())
 536             }
 537         })
 538         .map(|(_ptr, scope)| *scope)
 539 }
 540
 541 #[inline]
 542 pub(crate) fn resolve_hir_path(
 543     db: &dyn HirDatabase,
 544     resolver: &Resolver,
 545     path: &Path,
 546 ) -> Option<PathResolution> {
 547     resolve_hir_path_(db, resolver, path, false)
 548 }
 549
 550 #[inline]
 551 pub(crate) fn resolve_hir_path_as_macro(
 552     db: &dyn HirDatabase,
 553     resolver: &Resolver,
 554     path: &Path,
 555 ) -> Option<MacroDef> {
 556     resolver.resolve_path_as_macro(db.upcast(), path.mod_path()).map(Into::into)
 557 }
 558
 559 fn resolve_hir_path_(
 560     db: &dyn HirDatabase,
 561     resolver: &Resolver,
 562     path: &Path,
 563     prefer_value_ns: bool,
 564 ) -> Option<PathResolution> {
 565     let types = || {
 566         let (ty, unresolved) = match path.type_anchor() {
 567             Some(type_ref) => {
 568                 let (_, res) = TyLoweringContext::new(db, resolver).lower_ty_ext(type_ref);
 569                 res.map(|ty_ns| (ty_ns, path.segments().first()))
 570             }
 571             None => {
 572                 let (ty, remaining) =
 573                     resolver.resolve_path_in_type_ns(db.upcast(), path.mod_path())?;
 574                 match remaining {
 575                     Some(remaining) if remaining > 1 => None,
 576                     _ => Some((ty, path.segments().get(1))),
 577                 }
 578             }
 579         }?;
 580
 581         // If we are in a TypeNs for a Trait, and we have an unresolved name, try to resolve it as a type
 582         // within the trait's associated types.
 583         if let (Some(unresolved), &TypeNs::TraitId(trait_id)) = (&unresolved, &ty) {
 584             if let Some(type_alias_id) =
 585                 db.trait_data(trait_id).associated_type_by_name(&unresolved.name)
 586             {
 587                 return Some(PathResolution::Def(ModuleDefId::from(type_alias_id).into()));
 588             }
 589         }
 590
 591         let res = match ty {
 592             TypeNs::SelfType(it) => PathResolution::SelfType(it.into()),
 593             TypeNs::GenericParam(id) => PathResolution::TypeParam(TypeParam { id }),
 594             TypeNs::AdtSelfType(it) | TypeNs::AdtId(it) => {
 595                 PathResolution::Def(Adt::from(it).into())
 596             }
 597             TypeNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
 598             TypeNs::TypeAliasId(it) => PathResolution::Def(TypeAlias::from(it).into()),
 599             TypeNs::BuiltinType(it) => PathResolution::Def(BuiltinType::from(it).into()),
 600             TypeNs::TraitId(it) => PathResolution::Def(Trait::from(it).into()),
 601         };
 602         match unresolved {
 603             Some(unresolved) => res
 604                 .assoc_type_shorthand_candidates(db, |name, alias| {
 605                     (name == unresolved.name).then(|| alias)
 606                 })
 607                 .map(TypeAlias::from)
 608                 .map(Into::into)
 609                 .map(PathResolution::Def),
 610             None => Some(res),
 611         }
 612     };
 613
 614     let body_owner = resolver.body_owner();
 615     let values = || {
 616         resolver.resolve_path_in_value_ns_fully(db.upcast(), path.mod_path()).and_then(|val| {
 617             let res = match val {
 618                 ValueNs::LocalBinding(pat_id) => {
 619                     let var = Local { parent: body_owner?, pat_id };
 620                     PathResolution::Local(var)
 621                 }
 622                 ValueNs::FunctionId(it) => PathResolution::Def(Function::from(it).into()),
 623                 ValueNs::ConstId(it) => PathResolution::Def(Const::from(it).into()),
 624                 ValueNs::StaticId(it) => PathResolution::Def(Static::from(it).into()),
 625                 ValueNs::StructId(it) => PathResolution::Def(Struct::from(it).into()),
 626                 ValueNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
 627                 ValueNs::ImplSelf(impl_id) => PathResolution::SelfType(impl_id.into()),
 628                 ValueNs::GenericParam(it) => PathResolution::ConstParam(it.into()),
 629             };
 630             Some(res)
 631         })
 632     };
 633
 634     let items = || {
 635         resolver
 636             .resolve_module_path_in_items(db.upcast(), path.mod_path())
 637             .take_types()
 638             .map(|it| PathResolution::Def(it.into()))
 639     };
 640
 641     let macros = || {
 642         resolver
 643             .resolve_path_as_macro(db.upcast(), path.mod_path())
 644             .map(|def| PathResolution::Macro(def.into()))
 645     };
 646
 647     if prefer_value_ns { values().or_else(types) } else { types().or_else(values) }
 648         .or_else(items)
 649         .or_else(macros)
 650 }
 651
 652 /// Resolves a path where we know it is a qualifier of another path.
 653 ///
 654 /// For example, if we have:
 655 /// ```
 656 /// mod my {
 657 ///     pub mod foo {
 658 ///         struct Bar;
 659 ///     }
 660 ///
 661 ///     pub fn foo() {}
 662 /// }
 663 /// ```
 664 /// then we know that `foo` in `my::foo::Bar` refers to the module, not the function.
 665 fn resolve_hir_path_qualifier(
 666     db: &dyn HirDatabase,
 667     resolver: &Resolver,
 668     path: &Path,
 669 ) -> Option<PathResolution> {
 670     let items = resolver
 671         .resolve_module_path_in_items(db.upcast(), path.mod_path())
 672         .take_types()
 673         .map(|it| PathResolution::Def(it.into()));
 674
 675     if items.is_some() {
 676         return items;
 677     }
 678
 679     resolver.resolve_path_in_type_ns_fully(db.upcast(), path.mod_path()).map(|ty| match ty {
 680         TypeNs::SelfType(it) => PathResolution::SelfType(it.into()),
 681         TypeNs::GenericParam(id) => PathResolution::TypeParam(TypeParam { id }),
 682         TypeNs::AdtSelfType(it) | TypeNs::AdtId(it) => PathResolution::Def(Adt::from(it).into()),
 683         TypeNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
 684         TypeNs::TypeAliasId(it) => PathResolution::Def(TypeAlias::from(it).into()),
 685         TypeNs::BuiltinType(it) => PathResolution::Def(BuiltinType::from(it).into()),
 686         TypeNs::TraitId(it) => PathResolution::Def(Trait::from(it).into()),
 687     })
 688 }