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, NameClass, NameRefClass},
   6     helpers::{try_resolve_derive_input, FamousDefs},
   7     RootDatabase, SymbolKind,
   8 };
   9 use rustc_hash::FxHashMap;
  10 use syntax::{
  11     ast, match_ast, AstNode, AstToken, NodeOrToken, SyntaxElement,
  12     SyntaxKind::{self, *},
  13     SyntaxNode, SyntaxToken, T,
  14 };
  15
  16 use crate::{
  17     syntax_highlighting::tags::{HlOperator, HlPunct},
  18     Highlight, HlMod, HlTag,
  19 };
  20
  21 pub(super) fn element(
  22     sema: &Semantics<RootDatabase>,
  23     krate: Option<hir::Crate>,
  24     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
  25     syntactic_name_ref_highlighting: bool,
  26     element: SyntaxElement,
  27 ) -> Option<(Highlight, Option<u64>)> {
  28     match element {
  29         NodeOrToken::Node(it) => {
  30             node(sema, krate, bindings_shadow_count, syntactic_name_ref_highlighting, it)
  31         }
  32         NodeOrToken::Token(it) => Some((token(sema, krate, it)?, None)),
  33     }
  34 }
  35
  36 fn token(
  37     sema: &Semantics<RootDatabase>,
  38     krate: Option<hir::Crate>,
  39     token: SyntaxToken,
  40 ) -> Option<Highlight> {
  41     let highlight: Highlight = if let Some(comment) = ast::Comment::cast(token.clone()) {
  42         let h = HlTag::Comment;
  43         match comment.kind().doc {
  44             Some(_) => h | HlMod::Documentation,
  45             None => h.into(),
  46         }
  47     } else {
  48         match token.kind() {
  49             STRING | BYTE_STRING => HlTag::StringLiteral.into(),
  50             INT_NUMBER if token.ancestors().nth(1).map_or(false, |it| it.kind() == FIELD_EXPR) => {
  51                 SymbolKind::Field.into()
  52             }
  53             INT_NUMBER | FLOAT_NUMBER => HlTag::NumericLiteral.into(),
  54             BYTE => HlTag::ByteLiteral.into(),
  55             CHAR => HlTag::CharLiteral.into(),
  56             T![?] => HlTag::Operator(HlOperator::Other) | HlMod::ControlFlow,
  57             IDENT if parent_matches::<ast::TokenTree>(&token) => {
  58                 if let Some(attr) = token.ancestors().nth(2).and_then(ast::Attr::cast) {
  59                     match try_resolve_derive_input(sema, &attr, &ast::Ident::cast(token).unwrap()) {
  60                         Some(res) => highlight_def(sema, krate, Definition::from(res)),
  61                         None => HlTag::None.into(),
  62                     }
  63                 } else {
  64                     HlTag::None.into()
  65                 }
  66             }
  67             p if p.is_punct() => match p {
  68                 T![&] if parent_matches::<ast::BinExpr>(&token) => HlOperator::Bitwise.into(),
  69                 T![&] => {
  70                     let h = HlTag::Operator(HlOperator::Other).into();
  71                     let is_unsafe = token
  72                         .parent()
  73                         .and_then(ast::RefExpr::cast)
  74                         .map_or(false, |ref_expr| sema.is_unsafe_ref_expr(&ref_expr));
  75                     if is_unsafe {
  76                         h | HlMod::Unsafe
  77                     } else {
  78                         h
  79                     }
  80                 }
  81                 T![::] | T![->] | T![=>] | T![..] | T![=] | T![@] | T![.] => {
  82                     HlOperator::Other.into()
  83                 }
  84                 T![!] if parent_matches::<ast::MacroCall>(&token) => SymbolKind::Macro.into(),
  85                 T![!] if parent_matches::<ast::NeverType>(&token) => HlTag::BuiltinType.into(),
  86                 T![!] if parent_matches::<ast::PrefixExpr>(&token) => HlOperator::Logical.into(),
  87                 T![*] if parent_matches::<ast::PtrType>(&token) => HlTag::Keyword.into(),
  88                 T![*] if parent_matches::<ast::PrefixExpr>(&token) => {
  89                     let prefix_expr = token.parent().and_then(ast::PrefixExpr::cast)?;
  90
  91                     let expr = prefix_expr.expr()?;
  92                     let ty = sema.type_of_expr(&expr)?.original;
  93                     if ty.is_raw_ptr() {
  94                         HlTag::Operator(HlOperator::Other) | HlMod::Unsafe
  95                     } else if let Some(ast::UnaryOp::Deref) = prefix_expr.op_kind() {
  96                         HlOperator::Other.into()
  97                     } else {
  98                         HlPunct::Other.into()
  99                     }
 100                 }
 101                 T![-] if parent_matches::<ast::PrefixExpr>(&token) => {
 102                     let prefix_expr = token.parent().and_then(ast::PrefixExpr::cast)?;
 103
 104                     let expr = prefix_expr.expr()?;
 105                     match expr {
 106                         ast::Expr::Literal(_) => HlTag::NumericLiteral,
 107                         _ => HlTag::Operator(HlOperator::Other),
 108                     }
 109                     .into()
 110                 }
 111                 _ if parent_matches::<ast::PrefixExpr>(&token) => HlOperator::Other.into(),
 112                 T![+] | T![-] | T![*] | T![/] if parent_matches::<ast::BinExpr>(&token) => {
 113                     HlOperator::Arithmetic.into()
 114                 }
 115                 T![+=] | T![-=] | T![*=] | T![/=] if parent_matches::<ast::BinExpr>(&token) => {
 116                     Highlight::from(HlOperator::Arithmetic) | HlMod::Mutable
 117                 }
 118                 T![|] | T![&] | T![!] | T![^] if parent_matches::<ast::BinExpr>(&token) => {
 119                     HlOperator::Bitwise.into()
 120                 }
 121                 T![|=] | T![&=] | T![^=] if parent_matches::<ast::BinExpr>(&token) => {
 122                     Highlight::from(HlOperator::Bitwise) | HlMod::Mutable
 123                 }
 124                 T![&&] | T![||] if parent_matches::<ast::BinExpr>(&token) => {
 125                     HlOperator::Logical.into()
 126                 }
 127                 T![>] | T![<] | T![==] | T![>=] | T![<=] | T![!=]
 128                     if parent_matches::<ast::BinExpr>(&token) =>
 129                 {
 130                     HlOperator::Comparison.into()
 131                 }
 132                 _ if parent_matches::<ast::BinExpr>(&token) => HlOperator::Other.into(),
 133                 _ if parent_matches::<ast::RangeExpr>(&token) => HlOperator::Other.into(),
 134                 _ if parent_matches::<ast::RangePat>(&token) => HlOperator::Other.into(),
 135                 _ if parent_matches::<ast::RestPat>(&token) => HlOperator::Other.into(),
 136                 _ if parent_matches::<ast::Attr>(&token) => HlTag::AttributeBracket.into(),
 137                 kind => match kind {
 138                     T!['['] | T![']'] => HlPunct::Bracket,
 139                     T!['{'] | T!['}'] => HlPunct::Brace,
 140                     T!['('] | T![')'] => HlPunct::Parenthesis,
 141                     T![<] | T![>] => HlPunct::Angle,
 142                     T![,] => HlPunct::Comma,
 143                     T![:] => HlPunct::Colon,
 144                     T![;] => HlPunct::Semi,
 145                     T![.] => HlPunct::Dot,
 146                     _ => HlPunct::Other,
 147                 }
 148                 .into(),
 149             },
 150             k if k.is_keyword() => {
 151                 let h = Highlight::new(HlTag::Keyword);
 152                 match k {
 153                     T![await] => h | HlMod::Async | HlMod::ControlFlow,
 154                     T![break]
 155                     | T![continue]
 156                     | T![else]
 157                     | T![if]
 158                     | T![in]
 159                     | T![loop]
 160                     | T![match]
 161                     | T![return]
 162                     | T![while]
 163                     | T![yield] => h | HlMod::ControlFlow,
 164                     T![for] if !is_child_of_impl(&token) => h | HlMod::ControlFlow,
 165                     T![unsafe] => h | HlMod::Unsafe,
 166                     T![true] | T![false] => HlTag::BoolLiteral.into(),
 167                     // crate is handled just as a token if it's in an `extern crate`
 168                     T![crate] if parent_matches::<ast::ExternCrate>(&token) => h,
 169                     // self, crate and super are handled as either a Name or NameRef already
 170                     T![self] | T![crate] | T![super] => return None,
 171                     T![ref] => token
 172                         .parent()
 173                         .and_then(ast::IdentPat::cast)
 174                         .and_then(|ident_pat| {
 175                             (sema.is_unsafe_ident_pat(&ident_pat)).then(|| HlMod::Unsafe)
 176                         })
 177                         .map_or(h, |modifier| h | modifier),
 178                     T![async] => h | HlMod::Async,
 179                     _ => h,
 180                 }
 181             }
 182             _ => return None,
 183         }
 184     };
 185     Some(highlight)
 186 }
 187
 188 fn node(
 189     sema: &Semantics<RootDatabase>,
 190     krate: Option<hir::Crate>,
 191     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 192     syntactic_name_ref_highlighting: bool,
 193     node: SyntaxNode,
 194 ) -> Option<(Highlight, Option<u64>)> {
 195     let mut binding_hash = None;
 196     let highlight = match_ast! {
 197         match node {
 198             ast::Fn(__) => {
 199                 bindings_shadow_count.clear();
 200                 return None;
 201             },
 202             ast::Attr(__) => {
 203                 HlTag::AttributeBracket.into()
 204             },
 205             // Highlight definitions depending on the "type" of the definition.
 206             ast::Name(name) => {
 207                 highlight_name(sema, bindings_shadow_count, &mut binding_hash, krate, name)
 208             },
 209             // Highlight references like the definitions they resolve to
 210             ast::NameRef(name_ref) => {
 211                 highlight_name_ref(
 212                     sema,
 213                     krate,
 214                     bindings_shadow_count,
 215                     &mut binding_hash,
 216                     syntactic_name_ref_highlighting,
 217                     name_ref,
 218                 )
 219             },
 220             ast::Lifetime(lifetime) => {
 221                 match NameClass::classify_lifetime(sema, &lifetime) {
 222                     Some(NameClass::Definition(def)) => {
 223                         highlight_def(sema, krate, def) | HlMod::Definition
 224                     }
 225                     None => match NameRefClass::classify_lifetime(sema, &lifetime) {
 226                         Some(NameRefClass::Definition(def)) => highlight_def(sema, krate, def),
 227                         _ => SymbolKind::LifetimeParam.into(),
 228                     },
 229                     _ => Highlight::from(SymbolKind::LifetimeParam) | HlMod::Definition,
 230                 }
 231             },
 232             _ => return None,
 233         }
 234     };
 235     Some((highlight, binding_hash))
 236 }
 237
 238 fn highlight_name_ref(
 239     sema: &Semantics<RootDatabase>,
 240     krate: Option<hir::Crate>,
 241     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 242     binding_hash: &mut Option<u64>,
 243     syntactic_name_ref_highlighting: bool,
 244     name_ref: ast::NameRef,
 245 ) -> Highlight {
 246     let db = sema.db;
 247     highlight_method_call_by_name_ref(sema, krate, &name_ref).unwrap_or_else(|| {
 248         let name_class = match NameRefClass::classify(sema, &name_ref) {
 249             Some(name_kind) => name_kind,
 250             None => {
 251                 return if syntactic_name_ref_highlighting {
 252                     highlight_name_ref_by_syntax(name_ref, sema, krate)
 253                 } else {
 254                     // FIXME: Workaround for https://github.com/rust-analyzer/rust-analyzer/issues/10708
 255                     //
 256                     // Some popular proc macros (namely async_trait) will rewrite `self` in such a way that it no
 257                     // longer resolves via NameRefClass. If we can't be resolved, but we know we're a self token,
 258                     // within a function with a self param, pretend to still be `self`, rather than
 259                     // an unresolved reference.
 260                     if name_ref.self_token().is_some() && is_in_fn_with_self_param(&name_ref) {
 261                         SymbolKind::SelfParam.into()
 262                     } else {
 263                         HlTag::UnresolvedReference.into()
 264                     }
 265                 };
 266             }
 267         };
 268         let mut h = match name_class {
 269             NameRefClass::Definition(def) => {
 270                 if let Definition::Local(local) = &def {
 271                     if let Some(name) = local.name(db) {
 272                         let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 273                         *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 274                     }
 275                 };
 276
 277                 let mut h = highlight_def(sema, krate, def);
 278
 279                 match def {
 280                     Definition::Local(local)
 281                         if is_consumed_lvalue(name_ref.syntax(), &local, db) =>
 282                     {
 283                         h |= HlMod::Consuming;
 284                     }
 285                     Definition::Trait(trait_) if trait_.is_unsafe(db) => {
 286                         if ast::Impl::for_trait_name_ref(&name_ref)
 287                             .map_or(false, |impl_| impl_.unsafe_token().is_some())
 288                         {
 289                             h |= HlMod::Unsafe;
 290                         }
 291                     }
 292                     Definition::Field(field) => {
 293                         if let Some(parent) = name_ref.syntax().parent() {
 294                             if matches!(parent.kind(), FIELD_EXPR | RECORD_PAT_FIELD) {
 295                                 if let hir::VariantDef::Union(_) = field.parent_def(db) {
 296                                     h |= HlMod::Unsafe;
 297                                 }
 298                             }
 299                         }
 300                     }
 301                     _ => (),
 302                 }
 303
 304                 h
 305             }
 306             NameRefClass::FieldShorthand { .. } => SymbolKind::Field.into(),
 307         };
 308         if h.tag == HlTag::Symbol(SymbolKind::Module) {
 309             if name_ref.self_token().is_some() {
 310                 return SymbolKind::SelfParam.into();
 311             }
 312             if name_ref.crate_token().is_some() || name_ref.super_token().is_some() {
 313                 h.tag = HlTag::Keyword;
 314             }
 315         }
 316         h
 317     })
 318 }
 319
 320 fn highlight_name(
 321     sema: &Semantics<RootDatabase>,
 322     bindings_shadow_count: &mut FxHashMap<hir::Name, u32>,
 323     binding_hash: &mut Option<u64>,
 324     krate: Option<hir::Crate>,
 325     name: ast::Name,
 326 ) -> Highlight {
 327     let db = sema.db;
 328     let name_kind = NameClass::classify(sema, &name);
 329     if let Some(NameClass::Definition(Definition::Local(local))) = &name_kind {
 330         if let Some(name) = local.name(db) {
 331             let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
 332             *shadow_count += 1;
 333             *binding_hash = Some(calc_binding_hash(&name, *shadow_count))
 334         }
 335     };
 336     match name_kind {
 337         Some(NameClass::Definition(def)) => {
 338             let mut h = highlight_def(sema, krate, def) | HlMod::Definition;
 339             if let Definition::Trait(trait_) = &def {
 340                 if trait_.is_unsafe(db) {
 341                     h |= HlMod::Unsafe;
 342                 }
 343             }
 344             h
 345         }
 346         Some(NameClass::ConstReference(def)) => highlight_def(sema, krate, def),
 347         Some(NameClass::PatFieldShorthand { field_ref, .. }) => {
 348             let mut h = HlTag::Symbol(SymbolKind::Field).into();
 349             if let hir::VariantDef::Union(_) = field_ref.parent_def(db) {
 350                 h |= HlMod::Unsafe;
 351             }
 352             h
 353         }
 354         None => highlight_name_by_syntax(name) | HlMod::Definition,
 355     }
 356 }
 357
 358 fn calc_binding_hash(name: &hir::Name, shadow_count: u32) -> u64 {
 359     fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
 360         use std::{collections::hash_map::DefaultHasher, hash::Hasher};
 361
 362         let mut hasher = DefaultHasher::new();
 363         x.hash(&mut hasher);
 364         hasher.finish()
 365     }
 366
 367     hash((name, shadow_count))
 368 }
 369
 370 fn highlight_def(
 371     sema: &Semantics<RootDatabase>,
 372     krate: Option<hir::Crate>,
 373     def: Definition,
 374 ) -> Highlight {
 375     let db = sema.db;
 376     let mut h = match def {
 377         Definition::Macro(m) => Highlight::new(HlTag::Symbol(match m.kind() {
 378             hir::MacroKind::Declarative | hir::MacroKind::BuiltIn | hir::MacroKind::ProcMacro => {
 379                 SymbolKind::Macro
 380             }
 381             hir::MacroKind::Derive => SymbolKind::Derive,
 382             hir::MacroKind::Attr => SymbolKind::Attribute,
 383         })),
 384         Definition::Field(_) => Highlight::new(HlTag::Symbol(SymbolKind::Field)),
 385         Definition::Module(module) => {
 386             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Module));
 387             if module.parent(db).is_none() {
 388                 h |= HlMod::CrateRoot
 389             }
 390             h
 391         }
 392         Definition::Function(func) => {
 393             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Function));
 394             if let Some(item) = func.as_assoc_item(db) {
 395                 h |= HlMod::Associated;
 396                 match func.self_param(db) {
 397                     Some(sp) => match sp.access(db) {
 398                         hir::Access::Exclusive => {
 399                             h |= HlMod::Mutable;
 400                             h |= HlMod::Reference;
 401                         }
 402                         hir::Access::Shared => h |= HlMod::Reference,
 403                         hir::Access::Owned => h |= HlMod::Consuming,
 404                     },
 405                     None => h |= HlMod::Static,
 406                 }
 407
 408                 match item.container(db) {
 409                     hir::AssocItemContainer::Impl(i) => {
 410                         if i.trait_(db).is_some() {
 411                             h |= HlMod::Trait;
 412                         }
 413                     }
 414                     hir::AssocItemContainer::Trait(_t) => {
 415                         h |= HlMod::Trait;
 416                     }
 417                 }
 418             }
 419
 420             if func.is_unsafe(db) {
 421                 h |= HlMod::Unsafe;
 422             }
 423             if func.is_async(db) {
 424                 h |= HlMod::Async;
 425             }
 426
 427             h
 428         }
 429         Definition::Adt(adt) => {
 430             let h = match adt {
 431                 hir::Adt::Struct(_) => HlTag::Symbol(SymbolKind::Struct),
 432                 hir::Adt::Enum(_) => HlTag::Symbol(SymbolKind::Enum),
 433                 hir::Adt::Union(_) => HlTag::Symbol(SymbolKind::Union),
 434             };
 435
 436             Highlight::new(h)
 437         }
 438         Definition::Variant(_) => Highlight::new(HlTag::Symbol(SymbolKind::Variant)),
 439         Definition::Const(konst) => {
 440             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Const));
 441
 442             if let Some(item) = konst.as_assoc_item(db) {
 443                 h |= HlMod::Associated;
 444                 match item.container(db) {
 445                     hir::AssocItemContainer::Impl(i) => {
 446                         if i.trait_(db).is_some() {
 447                             h |= HlMod::Trait;
 448                         }
 449                     }
 450                     hir::AssocItemContainer::Trait(_t) => {
 451                         h |= HlMod::Trait;
 452                     }
 453                 }
 454             }
 455
 456             h
 457         }
 458         Definition::Trait(_) => Highlight::new(HlTag::Symbol(SymbolKind::Trait)),
 459         Definition::TypeAlias(type_) => {
 460             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::TypeAlias));
 461
 462             if let Some(item) = type_.as_assoc_item(db) {
 463                 h |= HlMod::Associated;
 464                 match item.container(db) {
 465                     hir::AssocItemContainer::Impl(i) => {
 466                         if i.trait_(db).is_some() {
 467                             h |= HlMod::Trait;
 468                         }
 469                     }
 470                     hir::AssocItemContainer::Trait(_t) => {
 471                         h |= HlMod::Trait;
 472                     }
 473                 }
 474             }
 475
 476             h
 477         }
 478         Definition::BuiltinType(_) => Highlight::new(HlTag::BuiltinType),
 479         Definition::Static(s) => {
 480             let mut h = Highlight::new(HlTag::Symbol(SymbolKind::Static));
 481
 482             if s.is_mut(db) {
 483                 h |= HlMod::Mutable;
 484                 h |= HlMod::Unsafe;
 485             }
 486
 487             h
 488         }
 489         Definition::SelfType(_) => Highlight::new(HlTag::Symbol(SymbolKind::Impl)),
 490         Definition::GenericParam(it) => match it {
 491             hir::GenericParam::TypeParam(_) => Highlight::new(HlTag::Symbol(SymbolKind::TypeParam)),
 492             hir::GenericParam::ConstParam(_) => {
 493                 Highlight::new(HlTag::Symbol(SymbolKind::ConstParam))
 494             }
 495             hir::GenericParam::LifetimeParam(_) => {
 496                 Highlight::new(HlTag::Symbol(SymbolKind::LifetimeParam))
 497             }
 498         },
 499         Definition::Local(local) => {
 500             let tag = if local.is_self(db) {
 501                 HlTag::Symbol(SymbolKind::SelfParam)
 502             } else if local.is_param(db) {
 503                 HlTag::Symbol(SymbolKind::ValueParam)
 504             } else {
 505                 HlTag::Symbol(SymbolKind::Local)
 506             };
 507             let mut h = Highlight::new(tag);
 508             let ty = local.ty(db);
 509             if local.is_mut(db) || ty.is_mutable_reference() {
 510                 h |= HlMod::Mutable;
 511             }
 512             if local.is_ref(db) || ty.is_reference() {
 513                 h |= HlMod::Reference;
 514             }
 515             if ty.as_callable(db).is_some() || ty.impls_fnonce(db) {
 516                 h |= HlMod::Callable;
 517             }
 518             h
 519         }
 520         Definition::Label(_) => Highlight::new(HlTag::Symbol(SymbolKind::Label)),
 521         Definition::BuiltinAttr(_) => Highlight::new(HlTag::Symbol(SymbolKind::BuiltinAttr)),
 522         Definition::ToolModule(_) => Highlight::new(HlTag::Symbol(SymbolKind::ToolModule)),
 523     };
 524
 525     let famous_defs = FamousDefs(sema, krate);
 526     let def_crate = def.module(db).map(hir::Module::krate).or_else(|| match def {
 527         Definition::Module(module) => Some(module.krate()),
 528         _ => None,
 529     });
 530     let is_from_other_crate = def_crate != krate;
 531     let is_from_builtin_crate =
 532         def_crate.map_or(false, |def_crate| famous_defs.builtin_crates().any(|it| def_crate == it));
 533     let is_builtin_type = matches!(def, Definition::BuiltinType(_));
 534     let is_public = def.visibility(db) == Some(hir::Visibility::Public);
 535
 536     match (is_from_other_crate, is_builtin_type, is_public) {
 537         (true, false, _) => h |= HlMod::Library,
 538         (false, _, true) => h |= HlMod::Public,
 539         _ => {}
 540     }
 541
 542     if is_from_builtin_crate {
 543         h |= HlMod::DefaultLibrary;
 544     }
 545
 546     h
 547 }
 548
 549 fn highlight_method_call_by_name_ref(
 550     sema: &Semantics<RootDatabase>,
 551     krate: Option<hir::Crate>,
 552     name_ref: &ast::NameRef,
 553 ) -> Option<Highlight> {
 554     let mc = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
 555     highlight_method_call(sema, krate, &mc)
 556 }
 557
 558 fn highlight_method_call(
 559     sema: &Semantics<RootDatabase>,
 560     krate: Option<hir::Crate>,
 561     method_call: &ast::MethodCallExpr,
 562 ) -> Option<Highlight> {
 563     let func = sema.resolve_method_call(method_call)?;
 564
 565     let mut h = SymbolKind::Function.into();
 566     h |= HlMod::Associated;
 567
 568     if func.is_unsafe(sema.db) || sema.is_unsafe_method_call(method_call) {
 569         h |= HlMod::Unsafe;
 570     }
 571     if func.is_async(sema.db) {
 572         h |= HlMod::Async;
 573     }
 574     if func.as_assoc_item(sema.db).and_then(|it| it.containing_trait(sema.db)).is_some() {
 575         h |= HlMod::Trait;
 576     }
 577
 578     let famous_defs = FamousDefs(sema, krate);
 579     let def_crate = func.module(sema.db).krate();
 580     let is_from_other_crate = Some(def_crate) != krate;
 581     let is_from_builtin_crate = famous_defs.builtin_crates().any(|it| def_crate == it);
 582     let is_public = func.visibility(sema.db) == hir::Visibility::Public;
 583
 584     if is_from_other_crate {
 585         h |= HlMod::Library;
 586     } else if is_public {
 587         h |= HlMod::Public;
 588     }
 589
 590     if is_from_builtin_crate {
 591         h |= HlMod::DefaultLibrary;
 592     }
 593
 594     if let Some(self_param) = func.self_param(sema.db) {
 595         match self_param.access(sema.db) {
 596             hir::Access::Shared => h |= HlMod::Reference,
 597             hir::Access::Exclusive => {
 598                 h |= HlMod::Mutable;
 599                 h |= HlMod::Reference;
 600             }
 601             hir::Access::Owned => {
 602                 if let Some(receiver_ty) =
 603                     method_call.receiver().and_then(|it| sema.type_of_expr(&it))
 604                 {
 605                     if !receiver_ty.adjusted().is_copy(sema.db) {
 606                         h |= HlMod::Consuming
 607                     }
 608                 }
 609             }
 610         }
 611     }
 612     Some(h)
 613 }
 614
 615 fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
 616     let default = HlTag::UnresolvedReference;
 617
 618     let parent = match name.syntax().parent() {
 619         Some(it) => it,
 620         _ => return default.into(),
 621     };
 622
 623     let tag = match parent.kind() {
 624         STRUCT => SymbolKind::Struct,
 625         ENUM => SymbolKind::Enum,
 626         VARIANT => SymbolKind::Variant,
 627         UNION => SymbolKind::Union,
 628         TRAIT => SymbolKind::Trait,
 629         TYPE_ALIAS => SymbolKind::TypeAlias,
 630         TYPE_PARAM => SymbolKind::TypeParam,
 631         RECORD_FIELD => SymbolKind::Field,
 632         MODULE => SymbolKind::Module,
 633         FN => SymbolKind::Function,
 634         CONST => SymbolKind::Const,
 635         STATIC => SymbolKind::Static,
 636         IDENT_PAT => SymbolKind::Local,
 637         _ => return default.into(),
 638     };
 639
 640     tag.into()
 641 }
 642
 643 fn highlight_name_ref_by_syntax(
 644     name: ast::NameRef,
 645     sema: &Semantics<RootDatabase>,
 646     krate: Option<hir::Crate>,
 647 ) -> Highlight {
 648     let default = HlTag::UnresolvedReference;
 649
 650     let parent = match name.syntax().parent() {
 651         Some(it) => it,
 652         _ => return default.into(),
 653     };
 654
 655     match parent.kind() {
 656         METHOD_CALL_EXPR => ast::MethodCallExpr::cast(parent)
 657             .and_then(|it| highlight_method_call(sema, krate, &it))
 658             .unwrap_or_else(|| SymbolKind::Function.into()),
 659         FIELD_EXPR => {
 660             let h = HlTag::Symbol(SymbolKind::Field);
 661             let is_union = ast::FieldExpr::cast(parent)
 662                 .and_then(|field_expr| sema.resolve_field(&field_expr))
 663                 .map_or(false, |field| {
 664                     matches!(field.parent_def(sema.db), hir::VariantDef::Union(_))
 665                 });
 666             if is_union {
 667                 h | HlMod::Unsafe
 668             } else {
 669                 h.into()
 670             }
 671         }
 672         PATH_SEGMENT => {
 673             let path = match parent.parent().and_then(ast::Path::cast) {
 674                 Some(it) => it,
 675                 _ => return default.into(),
 676             };
 677             let expr = match path.syntax().parent().and_then(ast::PathExpr::cast) {
 678                 Some(it) => it,
 679                 _ => {
 680                     // within path, decide whether it is module or adt by checking for uppercase name
 681                     return if name.text().chars().next().unwrap_or_default().is_uppercase() {
 682                         SymbolKind::Struct
 683                     } else {
 684                         SymbolKind::Module
 685                     }
 686                     .into();
 687                 }
 688             };
 689             let parent = match expr.syntax().parent() {
 690                 Some(it) => it,
 691                 None => return default.into(),
 692             };
 693
 694             match parent.kind() {
 695                 CALL_EXPR => SymbolKind::Function.into(),
 696                 _ => if name.text().chars().next().unwrap_or_default().is_uppercase() {
 697                     SymbolKind::Struct
 698                 } else {
 699                     SymbolKind::Const
 700                 }
 701                 .into(),
 702             }
 703         }
 704         _ => default.into(),
 705     }
 706 }
 707
 708 fn is_consumed_lvalue(node: &SyntaxNode, local: &hir::Local, db: &RootDatabase) -> bool {
 709     // When lvalues are passed as arguments and they're not Copy, then mark them as Consuming.
 710     parents_match(node.clone().into(), &[PATH_SEGMENT, PATH, PATH_EXPR, ARG_LIST])
 711         && !local.ty(db).is_copy(db)
 712 }
 713
 714 /// Returns true if the parent nodes of `node` all match the `SyntaxKind`s in `kinds` exactly.
 715 fn parents_match(mut node: NodeOrToken<SyntaxNode, SyntaxToken>, mut kinds: &[SyntaxKind]) -> bool {
 716     while let (Some(parent), [kind, rest @ ..]) = (&node.parent(), kinds) {
 717         if parent.kind() != *kind {
 718             return false;
 719         }
 720
 721         // FIXME: Would be nice to get parent out of the match, but binding by-move and by-value
 722         // in the same pattern is unstable: rust-lang/rust#68354.
 723         node = node.parent().unwrap().into();
 724         kinds = rest;
 725     }
 726
 727     // Only true if we matched all expected kinds
 728     kinds.is_empty()
 729 }
 730
 731 #[inline]
 732 fn parent_matches<N: AstNode>(token: &SyntaxToken) -> bool {
 733     token.parent().map_or(false, |it| N::can_cast(it.kind()))
 734 }
 735
 736 fn is_child_of_impl(token: &SyntaxToken) -> bool {
 737     match token.parent() {
 738         Some(e) => e.kind() == IMPL,
 739         _ => false,
 740     }
 741 }
 742
 743 fn is_in_fn_with_self_param<N: AstNode>(node: &N) -> bool {
 744     node.syntax()
 745         .ancestors()
 746         .find_map(ast::Fn::cast)
 747         .and_then(|s| s.param_list()?.self_param())
 748         .is_some()
 749 }