src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/highlight.rs

   1 //! Computes color for a single element.
   2
   3 use hir::{AsAssocItem, HasVisibility, Semantics};
   4 use ide_db::{
   5     defs::{Definition, IdentClass, NameClass, NameRefClass},
   6     FxHashMap, RootDatabase, SymbolKind,
   7 };
   8 use syntax::{
   9     ast, match_ast, AstNode, AstToken, NodeOrToken,
  10     SyntaxKind::{self, *},
  11     SyntaxNode, SyntaxToken, T,
  12 };
  13
  14 use crate::{
  15     syntax_highlighting::tags::{HlOperator, HlPunct},
  16     Highlight, HlMod, HlTag,
  17 };
  18
  19 pub(super) fn token(sema: &Semantics<'_, RootDatabase>, token: SyntaxToken) -> Option<Highlight> {
  20     if let Some(comment) = ast::Comment::cast(token.clone()) {
  21         let h = HlTag::Comment;
  22         return Some(match comment.kind().doc {
  23             Some(_) => h | HlMod::Documentation,
  24             None => h.into(),
  25         });
  26     }
  27
  28     let highlight: Highlight = match token.kind() {
  29         STRING | BYTE_STRING => HlTag::StringLiteral.into(),
  30         INT_NUMBER if token.parent_ancestors().nth(1).map(|it| it.kind()) == Some(FIELD_EXPR) => {
  31             SymbolKind::Field.into()
  32         }
  33         INT_NUMBER | FLOAT_NUMBER => HlTag::NumericLiteral.into(),
  34         BYTE => HlTag::ByteLiteral.into(),
  35         CHAR => HlTag::CharLiteral.into(),
  36         IDENT if token.parent().and_then(ast::TokenTree::cast).is_some() => {
  37             // from this point on we are inside a token tree, this only happens for identifiers
  38             // that were not mapped down into macro invocations
  39             HlTag::None.into()
  40         }
  41         p if p.is_punct() => punctuation(sema, token, p),
  42         k if k.is_keyword() => keyword(sema, token, k)?,
  43         _ => return None,
  44     };
  45     Some(highlight)
  46 }
  47
  48 pub(super) fn name_like(
  49     sema: &Semantics<'_, RootDatabase>,
  50     krate: hir::Crate,
  51     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
  52     syntactic_name_ref_highlighting: bool,
  53     name_like: ast::NameLike,
  54 ) -> Option<(Highlight, Option<u64>)> {
  55     let mut binding_hash = None;
  56     let highlight = match name_like {
  57         ast::NameLike::NameRef(name_ref) => highlight_name_ref(
  58             sema,
  59             krate,
  60             bindings_shadow_count,
  61             &mut binding_hash,
  62             syntactic_name_ref_highlighting,
  63             name_ref,
  64         ),
  65         ast::NameLike::Name(name) => {
  66             highlight_name(sema, bindings_shadow_count, &mut binding_hash, krate, name)
  67         }
  68         ast::NameLike::Lifetime(lifetime) => match IdentClass::classify_lifetime(sema, &lifetime) {
  69             Some(IdentClass::NameClass(NameClass::Definition(def))) => {
  70                 highlight_def(sema, krate, def) | HlMod::Definition
  71             }
  72             Some(IdentClass::NameRefClass(NameRefClass::Definition(def))) => {
  73                 highlight_def(sema, krate, def)
  74             }
  75             // FIXME: Fallback for 'static and '_, as we do not resolve these yet
  76             _ => SymbolKind::LifetimeParam.into(),
  77         },
  78     };
  79     Some((highlight, binding_hash))
  80 }
  81
  82 fn punctuation(
  83     sema: &Semantics<'_, RootDatabase>,
  84     token: SyntaxToken,
  85     kind: SyntaxKind,
  86 ) -> Highlight {
  87     let parent = token.parent();
  88     let parent_kind = parent.as_ref().map_or(EOF, SyntaxNode::kind);
  89     match (kind, parent_kind) {
  90         (T![?], TRY_EXPR) => HlTag::Operator(HlOperator::Other) | HlMod::ControlFlow,
  91         (T![&], BIN_EXPR) => HlOperator::Bitwise.into(),
  92         (T![&], REF_EXPR) => {
  93             let h = HlTag::Operator(HlOperator::Other).into();
  94             let is_unsafe = parent
  95                 .and_then(ast::RefExpr::cast)
  96                 .map(|ref_expr| sema.is_unsafe_ref_expr(&ref_expr));
  97             if let Some(true) = is_unsafe {
  98                 h | HlMod::Unsafe
  99             } else {
 100                 h
 101             }
 102         }
 103         (T![::] | T![->] | T![=>] | T![..] | T![..=] | T![=] | T![@] | T![.], _) => {
 104             HlOperator::Other.into()
 105         }
 106         (T![!], MACRO_CALL | MACRO_RULES) => HlPunct::MacroBang.into(),
 107         (T![!], NEVER_TYPE) => HlTag::BuiltinType.into(),
 108         (T![!], PREFIX_EXPR) => HlOperator::Logical.into(),
 109         (T![*], PTR_TYPE) => HlTag::Keyword.into(),
 110         (T![*], PREFIX_EXPR) => {
 111             let is_raw_ptr = (|| {
 112                 let prefix_expr = parent.and_then(ast::PrefixExpr::cast)?;
 113                 let expr = prefix_expr.expr()?;
 114                 sema.type_of_expr(&expr)?.original.is_raw_ptr().then_some(())
 115             })();
 116             if let Some(()) = is_raw_ptr {
 117                 HlTag::Operator(HlOperator::Other) | HlMod::Unsafe
 118             } else {
 119                 HlOperator::Other.into()
 120             }
 121         }
 122         (T![-], PREFIX_EXPR) => {
 123             let prefix_expr = parent.and_then(ast::PrefixExpr::cast).and_then(|e| e.expr());
 124             match prefix_expr {
 125                 Some(ast::Expr::Literal(_)) => HlTag::NumericLiteral,
 126                 _ => HlTag::Operator(HlOperator::Other),
 127             }
 128             .into()
 129         }
 130         (T![+] | T![-] | T![*] | T![/] | T![%], BIN_EXPR) => HlOperator::Arithmetic.into(),
 131         (T![+=] | T![-=] | T![*=] | T![/=] | T![%=], BIN_EXPR) => {
 132             Highlight::from(HlOperator::Arithmetic) | HlMod::Mutable
 133         }
 134         (T![|] | T![&] | T![^] | T![>>] | T![<<], BIN_EXPR) => HlOperator::Bitwise.into(),
 135         (T![|=] | T![&=] | T![^=] | T![>>=] | T![<<=], BIN_EXPR) => {
 136             Highlight::from(HlOperator::Bitwise) | HlMod::Mutable
 137         }
 138         (T![&&] | T![||], BIN_EXPR) => HlOperator::Logical.into(),
 139         (T![>] | T![<] | T![==] | T![>=] | T![<=] | T![!=], BIN_EXPR) => {
 140             HlOperator::Comparison.into()
 141         }
 142         (_, ATTR) => HlTag::AttributeBracket.into(),
 143         (kind, _) => match kind {
 144             T!['['] | T![']'] => HlPunct::Bracket,
 145             T!['{'] | T!['}'] => HlPunct::Brace,
 146             T!['('] | T![')'] => HlPunct::Parenthesis,
 147             T![<] | T![>] => HlPunct::Angle,
 148             T![,] => HlPunct::Comma,
 149             T![:] => HlPunct::Colon,
 150             T![;] => HlPunct::Semi,
 151             T![.] => HlPunct::Dot,
 152             _ => HlPunct::Other,
 153         }
 154         .into(),
 155     }
 156 }
 157
 158 fn keyword(
 159     sema: &Semantics<'_, RootDatabase>,
 160     token: SyntaxToken,
 161     kind: SyntaxKind,
 162 ) -> Option<Highlight> {
 163     let h = Highlight::new(HlTag::Keyword);
 164     let h = match kind {
 165         T![await] => h | HlMod::Async | HlMod::ControlFlow,
 166         T![async] => h | HlMod::Async,
 167         T![break]
 168         | T![continue]
 169         | T![else]
 170         | T![if]
 171         | T![in]
 172         | T![loop]
 173         | T![match]
 174         | T![return]
 175         | T![while]
 176         | T![yield] => h | HlMod::ControlFlow,
 177         T![do] | T![yeet] if parent_matches::<ast::YeetExpr>(&token) => h | HlMod::ControlFlow,
 178         T![for] if parent_matches::<ast::ForExpr>(&token) => h | HlMod::ControlFlow,
 179         T![unsafe] => h | HlMod::Unsafe,
 180         T![true] | T![false] => HlTag::BoolLiteral.into(),
 181         // crate is handled just as a token if it's in an `extern crate`
 182         T![crate] if parent_matches::<ast::ExternCrate>(&token) => h,
 183         // self, crate, super and `Self` are handled as either a Name or NameRef already, unless they
 184         // are inside unmapped token trees
 185         T![self] | T![crate] | T![super] | T![Self] if parent_matches::<ast::NameRef>(&token) => {
 186             return None
 187         }
 188         T![self] if parent_matches::<ast::Name>(&token) => return None,
 189         T![ref] => match token.parent().and_then(ast::IdentPat::cast) {
 190             Some(ident) if sema.is_unsafe_ident_pat(&ident) => h | HlMod::Unsafe,
 191             _ => h,
 192         },
 193         _ => h,
 194     };
 195     Some(h)
 196 }
 197
 198 fn highlight_name_ref(
 199     sema: &Semantics<'_, RootDatabase>,
 200     krate: hir::Crate,
 201     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 202     binding_hash: &mut Option<u64>,
 203     syntactic_name_ref_highlighting: bool,
 204     name_ref: ast::NameRef,
 205 ) -> Highlight {
 206     let db = sema.db;
 207     if let Some(res) = highlight_method_call_by_name_ref(sema, krate, &name_ref) {
 208         return res;
 209     }
 210
 211     let name_class = match NameRefClass::classify(sema, &name_ref) {
 212         Some(name_kind) => name_kind,
 213         None if syntactic_name_ref_highlighting => {
 214             return highlight_name_ref_by_syntax(name_ref, sema, krate)
 215         }
 216         // FIXME: This is required for helper attributes used by proc-macros, as those do not map down
 217         // to anything when used.
 218         // We can fix this for derive attributes since derive helpers are recorded, but not for
 219         // general attributes.
 220         None if name_ref.syntax().ancestors().any(|it| it.kind() == ATTR)
 221             && !sema.hir_file_for(name_ref.syntax()).is_derive_attr_pseudo_expansion(sema.db) =>
 222         {
 223             return HlTag::Symbol(SymbolKind::Attribute).into();
 224         }
 225         None => return HlTag::UnresolvedReference.into(),
 226     };
 227     let mut h = match name_class {
 228         NameRefClass::Definition(def) => {
 229             if let Definition::Local(local) = &def {
 230                 let name = local.name(db);
 231                 let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 232                 *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 233             };
 234
 235             let mut h = highlight_def(sema, krate, def);
 236
 237             match def {
 238                 Definition::Local(local) if is_consumed_lvalue(name_ref.syntax(), &local, db) => {
 239                     h |= HlMod::Consuming;
 240                 }
 241                 Definition::Trait(trait_) if trait_.is_unsafe(db) => {
 242                     if ast::Impl::for_trait_name_ref(&name_ref)
 243                         .map_or(false, |impl_| impl_.unsafe_token().is_some())
 244                     {
 245                         h |= HlMod::Unsafe;
 246                     }
 247                 }
 248                 Definition::Field(field) => {
 249                     if let Some(parent) = name_ref.syntax().parent() {
 250                         if matches!(parent.kind(), FIELD_EXPR | RECORD_PAT_FIELD) {
 251                             if let hir::VariantDef::Union(_) = field.parent_def(db) {
 252                                 h |= HlMod::Unsafe;
 253                             }
 254                         }
 255                     }
 256                 }
 257                 Definition::Macro(_) => {
 258                     if let Some(macro_call) =
 259                         ide_db::syntax_helpers::node_ext::full_path_of_name_ref(&name_ref)
 260                             .and_then(|it| it.syntax().parent().and_then(ast::MacroCall::cast))
 261                     {
 262                         if sema.is_unsafe_macro_call(&macro_call) {
 263                             h |= HlMod::Unsafe;
 264                         }
 265                     }
 266                 }
 267                 _ => (),
 268             }
 269
 270             h
 271         }
 272         NameRefClass::FieldShorthand { .. } => SymbolKind::Field.into(),
 273     };
 274
 275     h.tag = match name_ref.token_kind() {
 276         T![Self] => HlTag::Symbol(SymbolKind::SelfType),
 277         T![self] => HlTag::Symbol(SymbolKind::SelfParam),
 278         T![super] | T![crate] => HlTag::Keyword,
 279         _ => h.tag,
 280     };
 281     h
 282 }
 283
 284 fn highlight_name(
 285     sema: &Semantics<'_, RootDatabase>,
 286     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 287     binding_hash: &mut Option<u64>,
 288     krate: hir::Crate,
 289     name: ast::Name,
 290 ) -> Highlight {
 291     let name_kind = NameClass::classify(sema, &name);
 292     if let Some(NameClass::Definition(Definition::Local(local))) = &name_kind {
 293         let name = local.name(sema.db);
 294         let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 295         *shadow_count += 1;
 296         *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 297     };
 298     match name_kind {
 299         Some(NameClass::Definition(def)) => {
 300             let mut h = highlight_def(sema, krate, def) | HlMod::Definition;
 301             if let Definition::Trait(trait_) = &def {
 302                 if trait_.is_unsafe(sema.db) {
 303                     h |= HlMod::Unsafe;
 304                 }
 305             }
 306             h
 307         }
 308         Some(NameClass::ConstReference(def)) => highlight_def(sema, krate, def),
 309         Some(NameClass::PatFieldShorthand { field_ref, .. }) => {
 310             let mut h = HlTag::Symbol(SymbolKind::Field).into();
 311             if let hir::VariantDef::Union(_) = field_ref.parent_def(sema.db) {
 312                 h |= HlMod::Unsafe;
 313             }
 314             h
 315         }
 316         None => highlight_name_by_syntax(name) | HlMod::Definition,
 317     }
 318 }
 319
 320 fn calc_binding_hash(name: &hir::Name, shadow_count: u32) -> u64 {
 321     fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
 322         use std::{collections::hash_map::DefaultHasher, hash::Hasher};
 323
 324         let mut hasher = DefaultHasher::new();
 325         x.hash(&mut hasher);
 326         hasher.finish()
 327     }
 328
 329     hash((name, shadow_count))
 330 }
 331
 332 fn highlight_def(
 333     sema: &Semantics<'_, RootDatabase>,
 334     krate: hir::Crate,
 335     def: Definition,
 336 ) -> Highlight {
 337     let db = sema.db;
 338     let mut h = match def {
 339         Definition::Macro(m) => Highlight::new(HlTag::Symbol(m.kind(sema.db).into())),
 340         Definition::Field(_) => Highlight::new(HlTag::Symbol(SymbolKind::Field)),
 341         Definition::Module(module) => {
 342             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Module));
 343             if module.is_crate_root(db) {
 344                 h |= HlMod::CrateRoot;
 345             }
 346             h
 347         }
 348         Definition::Function(func) => {
 349             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Function));
 350             if let Some(item) = func.as_assoc_item(db) {
 351                 h |= HlMod::Associated;
 352                 match func.self_param(db) {
 353                     Some(sp) => match sp.access(db) {
 354                         hir::Access::Exclusive => {
 355                             h |= HlMod::Mutable;
 356                             h |= HlMod::Reference;
 357                         }
 358                         hir::Access::Shared => h |= HlMod::Reference,
 359                         hir::Access::Owned => h |= HlMod::Consuming,
 360                     },
 361                     None => h |= HlMod::Static,
 362                 }
 363
 364                 match item.container(db) {
 365                     hir::AssocItemContainer::Impl(i) => {
 366                         if i.trait_(db).is_some() {
 367                             h |= HlMod::Trait;
 368                         }
 369                     }
 370                     hir::AssocItemContainer::Trait(_t) => {
 371                         h |= HlMod::Trait;
 372                     }
 373                 }
 374             }
 375
 376             if func.is_unsafe_to_call(db) {
 377                 h |= HlMod::Unsafe;
 378             }
 379             if func.is_async(db) {
 380                 h |= HlMod::Async;
 381             }
 382
 383             h
 384         }
 385         Definition::Adt(adt) => {
 386             let h = match adt {
 387                 hir::Adt::Struct(_) => HlTag::Symbol(SymbolKind::Struct),
 388                 hir::Adt::Enum(_) => HlTag::Symbol(SymbolKind::Enum),
 389                 hir::Adt::Union(_) => HlTag::Symbol(SymbolKind::Union),
 390             };
 391
 392             Highlight::new(h)
 393         }
 394         Definition::Variant(_) => Highlight::new(HlTag::Symbol(SymbolKind::Variant)),
 395         Definition::Const(konst) => {
 396             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Const));
 397
 398             if let Some(item) = konst.as_assoc_item(db) {
 399                 h |= HlMod::Associated;
 400                 match item.container(db) {
 401                     hir::AssocItemContainer::Impl(i) => {
 402                         if i.trait_(db).is_some() {
 403                             h |= HlMod::Trait;
 404                         }
 405                     }
 406                     hir::AssocItemContainer::Trait(_t) => {
 407                         h |= HlMod::Trait;
 408                     }
 409                 }
 410             }
 411
 412             h
 413         }
 414         Definition::Trait(_) => Highlight::new(HlTag::Symbol(SymbolKind::Trait)),
 415         Definition::TraitAlias(_) => Highlight::new(HlTag::Symbol(SymbolKind::TraitAlias)),
 416         Definition::TypeAlias(type_) => {
 417             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::TypeAlias));
 418
 419             if let Some(item) = type_.as_assoc_item(db) {
 420                 h |= HlMod::Associated;
 421                 match item.container(db) {
 422                     hir::AssocItemContainer::Impl(i) => {
 423                         if i.trait_(db).is_some() {
 424                             h |= HlMod::Trait;
 425                         }
 426                     }
 427                     hir::AssocItemContainer::Trait(_t) => {
 428                         h |= HlMod::Trait;
 429                     }
 430                 }
 431             }
 432
 433             h
 434         }
 435         Definition::BuiltinType(_) => Highlight::new(HlTag::BuiltinType),
 436         Definition::Static(s) => {
 437             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Static));
 438
 439             if s.is_mut(db) {
 440                 h |= HlMod::Mutable;
 441                 h |= HlMod::Unsafe;
 442             }
 443
 444             h
 445         }
 446         Definition::SelfType(_) => Highlight::new(HlTag::Symbol(SymbolKind::Impl)),
 447         Definition::GenericParam(it) => match it {
 448             hir::GenericParam::TypeParam(_) => Highlight::new(HlTag::Symbol(SymbolKind::TypeParam)),
 449             hir::GenericParam::ConstParam(_) => {
 450                 Highlight::new(HlTag::Symbol(SymbolKind::ConstParam))
 451             }
 452             hir::GenericParam::LifetimeParam(_) => {
 453                 Highlight::new(HlTag::Symbol(SymbolKind::LifetimeParam))
 454             }
 455         },
 456         Definition::Local(local) => {
 457             let tag = if local.is_self(db) {
 458                 HlTag::Symbol(SymbolKind::SelfParam)
 459             } else if local.is_param(db) {
 460                 HlTag::Symbol(SymbolKind::ValueParam)
 461             } else {
 462                 HlTag::Symbol(SymbolKind::Local)
 463             };
 464             let mut h = Highlight::new(tag);
 465             let ty = local.ty(db);
 466             if local.is_mut(db) || ty.is_mutable_reference() {
 467                 h |= HlMod::Mutable;
 468             }
 469             if local.is_ref(db) || ty.is_reference() {
 470                 h |= HlMod::Reference;
 471             }
 472             if ty.as_callable(db).is_some() || ty.impls_fnonce(db) {
 473                 h |= HlMod::Callable;
 474             }
 475             h
 476         }
 477         Definition::Label(_) => Highlight::new(HlTag::Symbol(SymbolKind::Label)),
 478         Definition::BuiltinAttr(_) => Highlight::new(HlTag::Symbol(SymbolKind::BuiltinAttr)),
 479         Definition::ToolModule(_) => Highlight::new(HlTag::Symbol(SymbolKind::ToolModule)),
 480         Definition::DeriveHelper(_) => Highlight::new(HlTag::Symbol(SymbolKind::DeriveHelper)),
 481     };
 482
 483     let def_crate = def.krate(db);
 484     let is_from_other_crate = def_crate != Some(krate);
 485     let is_from_builtin_crate = def_crate.map_or(false, |def_crate| def_crate.is_builtin(db));
 486     let is_builtin_type = matches!(def, Definition::BuiltinType(_));
 487     let is_public = def.visibility(db) == Some(hir::Visibility::Public);
 488
 489     match (is_from_other_crate, is_builtin_type, is_public) {
 490         (true, false, _) => h |= HlMod::Library,
 491         (false, _, true) => h |= HlMod::Public,
 492         _ => {}
 493     }
 494
 495     if is_from_builtin_crate {
 496         h |= HlMod::DefaultLibrary;
 497     }
 498
 499     h
 500 }
 501
 502 fn highlight_method_call_by_name_ref(
 503     sema: &Semantics<'_, RootDatabase>,
 504     krate: hir::Crate,
 505     name_ref: &ast::NameRef,
 506 ) -> Option<Highlight> {
 507     let mc = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
 508     highlight_method_call(sema, krate, &mc)
 509 }
 510
 511 fn highlight_method_call(
 512     sema: &Semantics<'_, RootDatabase>,
 513     krate: hir::Crate,
 514     method_call: &ast::MethodCallExpr,
 515 ) -> Option<Highlight> {
 516     let func = sema.resolve_method_call(method_call)?;
 517
 518     let mut h = SymbolKind::Function.into();
 519     h |= HlMod::Associated;
 520
 521     if func.is_unsafe_to_call(sema.db) || sema.is_unsafe_method_call(method_call) {
 522         h |= HlMod::Unsafe;
 523     }
 524     if func.is_async(sema.db) {
 525         h |= HlMod::Async;
 526     }
 527     if func
 528         .as_assoc_item(sema.db)
 529         .and_then(|it| it.containing_trait_or_trait_impl(sema.db))
 530         .is_some()
 531     {
 532         h |= HlMod::Trait;
 533     }
 534
 535     let def_crate = func.module(sema.db).krate();
 536     let is_from_other_crate = def_crate != krate;
 537     let is_from_builtin_crate = def_crate.is_builtin(sema.db);
 538     let is_public = func.visibility(sema.db) == hir::Visibility::Public;
 539
 540     if is_from_other_crate {
 541         h |= HlMod::Library;
 542     } else if is_public {
 543         h |= HlMod::Public;
 544     }
 545
 546     if is_from_builtin_crate {
 547         h |= HlMod::DefaultLibrary;
 548     }
 549
 550     if let Some(self_param) = func.self_param(sema.db) {
 551         match self_param.access(sema.db) {
 552             hir::Access::Shared => h |= HlMod::Reference,
 553             hir::Access::Exclusive => {
 554                 h |= HlMod::Mutable;
 555                 h |= HlMod::Reference;
 556             }
 557             hir::Access::Owned => {
 558                 if let Some(receiver_ty) =
 559                     method_call.receiver().and_then(|it| sema.type_of_expr(&it))
 560                 {
 561                     if !receiver_ty.adjusted().is_copy(sema.db) {
 562                         h |= HlMod::Consuming
 563                     }
 564                 }
 565             }
 566         }
 567     }
 568     Some(h)
 569 }
 570
 571 fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
 572     let default = HlTag::UnresolvedReference;
 573
 574     let parent = match name.syntax().parent() {
 575         Some(it) => it,
 576         _ => return default.into(),
 577     };
 578
 579     let tag = match parent.kind() {
 580         STRUCT => SymbolKind::Struct,
 581         ENUM => SymbolKind::Enum,
 582         VARIANT => SymbolKind::Variant,
 583         UNION => SymbolKind::Union,
 584         TRAIT => SymbolKind::Trait,
 585         TYPE_ALIAS => SymbolKind::TypeAlias,
 586         TYPE_PARAM => SymbolKind::TypeParam,
 587         RECORD_FIELD => SymbolKind::Field,
 588         MODULE => SymbolKind::Module,
 589         FN => SymbolKind::Function,
 590         CONST => SymbolKind::Const,
 591         STATIC => SymbolKind::Static,
 592         IDENT_PAT => SymbolKind::Local,
 593         _ => return default.into(),
 594     };
 595
 596     tag.into()
 597 }
 598
 599 fn highlight_name_ref_by_syntax(
 600     name: ast::NameRef,
 601     sema: &Semantics<'_, RootDatabase>,
 602     krate: hir::Crate,
 603 ) -> Highlight {
 604     let default = HlTag::UnresolvedReference;
 605
 606     let parent = match name.syntax().parent() {
 607         Some(it) => it,
 608         _ => return default.into(),
 609     };
 610
 611     match parent.kind() {
 612         METHOD_CALL_EXPR => ast::MethodCallExpr::cast(parent)
 613             .and_then(|it| highlight_method_call(sema, krate, &it))
 614             .unwrap_or_else(|| SymbolKind::Function.into()),
 615         FIELD_EXPR => {
 616             let h = HlTag::Symbol(SymbolKind::Field);
 617             let is_union = ast::FieldExpr::cast(parent)
 618                 .and_then(|field_expr| sema.resolve_field(&field_expr))
 619                 .map_or(false, |field| {
 620                     matches!(field.parent_def(sema.db), hir::VariantDef::Union(_))
 621                 });
 622             if is_union {
 623                 h | HlMod::Unsafe
 624             } else {
 625                 h.into()
 626             }
 627         }
 628         PATH_SEGMENT => {
 629             let name_based_fallback = || {
 630                 if name.text().chars().next().unwrap_or_default().is_uppercase() {
 631                     SymbolKind::Struct.into()
 632                 } else {
 633                     SymbolKind::Module.into()
 634                 }
 635             };
 636             let path = match parent.parent().and_then(ast::Path::cast) {
 637                 Some(it) => it,
 638                 _ => return name_based_fallback(),
 639             };
 640             let expr = match path.syntax().parent() {
 641                 Some(parent) => match_ast! {
 642                     match parent {
 643                         ast::PathExpr(path) => path,
 644                         ast::MacroCall(_) => return SymbolKind::Macro.into(),
 645                         _ => return name_based_fallback(),
 646                     }
 647                 },
 648                 // within path, decide whether it is module or adt by checking for uppercase name
 649                 None => return name_based_fallback(),
 650             };
 651             let parent = match expr.syntax().parent() {
 652                 Some(it) => it,
 653                 None => return default.into(),
 654             };
 655
 656             match parent.kind() {
 657                 CALL_EXPR => SymbolKind::Function.into(),
 658                 _ => if name.text().chars().next().unwrap_or_default().is_uppercase() {
 659                     SymbolKind::Struct
 660                 } else {
 661                     SymbolKind::Const
 662                 }
 663                 .into(),
 664             }
 665         }
 666         _ => default.into(),
 667     }
 668 }
 669
 670 fn is_consumed_lvalue(node: &SyntaxNode, local: &hir::Local, db: &RootDatabase) -> bool {
 671     // When lvalues are passed as arguments and they're not Copy, then mark them as Consuming.
 672     parents_match(node.clone().into(), &[PATH_SEGMENT, PATH, PATH_EXPR, ARG_LIST])
 673         && !local.ty(db).is_copy(db)
 674 }
 675
 676 /// Returns true if the parent nodes of `node` all match the `SyntaxKind`s in `kinds` exactly.
 677 fn parents_match(mut node: NodeOrToken<SyntaxNode, SyntaxToken>, mut kinds: &[SyntaxKind]) -> bool {
 678     while let (Some(parent), [kind, rest @ ..]) = (&node.parent(), kinds) {
 679         if parent.kind() != *kind {
 680             return false;
 681         }
 682
 683         // FIXME: Would be nice to get parent out of the match, but binding by-move and by-value
 684         // in the same pattern is unstable: rust-lang/rust#68354.
 685         node = node.parent().unwrap().into();
 686         kinds = rest;
 687     }
 688
 689     // Only true if we matched all expected kinds
 690     kinds.is_empty()
 691 }
 692
 693 fn parent_matches<N: AstNode>(token: &SyntaxToken) -> bool {
 694     token.parent().map_or(false, |it| N::can_cast(it.kind()))
 695 }