crates/ide-completion/src/context.rs

   1 //! See `CompletionContext` structure.
   2
   3 use std::iter;
   4
   5 use base_db::SourceDatabaseExt;
   6 use hir::{
   7     HasAttrs, Local, Name, PathResolution, ScopeDef, Semantics, SemanticsScope, Type, TypeInfo,
   8 };
   9 use ide_db::{
  10     active_parameter::ActiveParameter,
  11     base_db::{FilePosition, SourceDatabase},
  12     famous_defs::FamousDefs,
  13     FxHashMap, FxHashSet, RootDatabase,
  14 };
  15 use syntax::{
  16     algo::{find_node_at_offset, non_trivia_sibling},
  17     ast::{self, AttrKind, HasArgList, HasName, NameOrNameRef},
  18     match_ast, AstNode, AstToken, NodeOrToken,
  19     SyntaxKind::{self, *},
  20     SyntaxNode, SyntaxToken, TextRange, TextSize, T,
  21 };
  22 use text_edit::Indel;
  23
  24 use crate::{
  25     patterns::{
  26         determine_location, determine_prev_sibling, is_in_loop_body, is_in_token_of_for_loop,
  27         previous_token, ImmediateLocation, ImmediatePrevSibling,
  28     },
  29     CompletionConfig,
  30 };
  31
  32 const COMPLETION_MARKER: &str = "intellijRulezz";
  33
  34 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  35 pub(crate) enum PatternRefutability {
  36     Refutable,
  37     Irrefutable,
  38 }
  39
  40 pub(crate) enum Visible {
  41     Yes,
  42     Editable,
  43     No,
  44 }
  45
  46 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  47 pub(super) enum PathKind {
  48     Expr {
  49         in_block_expr: bool,
  50         in_loop_body: bool,
  51     },
  52     Type,
  53     Attr {
  54         kind: AttrKind,
  55         annotated_item_kind: Option<SyntaxKind>,
  56     },
  57     Derive,
  58     /// Path in item position, that is inside an (Assoc)ItemList
  59     Item {
  60         kind: ItemListKind,
  61     },
  62     Pat,
  63     Vis {
  64         has_in_token: bool,
  65     },
  66     Use,
  67 }
  68
  69 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  70 pub(super) enum ItemListKind {
  71     SourceFile,
  72     Module,
  73     Impl,
  74     Trait,
  75     ExternBlock,
  76 }
  77
  78 #[derive(Debug)]
  79 pub(crate) struct PathCompletionCtx {
  80     /// If this is a call with () already there (or {} in case of record patterns)
  81     pub(super) has_call_parens: bool,
  82     /// If this has a macro call bang !
  83     pub(super) has_macro_bang: bool,
  84     /// Whether this path stars with a `::`.
  85     pub(super) is_absolute_path: bool,
  86     /// The qualifier of the current path if it exists.
  87     pub(super) qualifier: Option<PathQualifierCtx>,
  88     #[allow(dead_code)]
  89     // FIXME: use this
  90     /// The parent of the path we are completing.
  91     pub(super) parent: Option<ast::Path>,
  92     pub(super) kind: PathKind,
  93     /// Whether the path segment has type args or not.
  94     pub(super) has_type_args: bool,
  95 }
  96
  97 #[derive(Debug)]
  98 pub(crate) struct PathQualifierCtx {
  99     pub(crate) path: ast::Path,
 100     pub(crate) resolution: Option<PathResolution>,
 101     /// Whether this path consists solely of `super` segments
 102     pub(crate) is_super_chain: bool,
 103     /// Whether the qualifier comes from a use tree parent or not
 104     pub(crate) use_tree_parent: bool,
 105     /// <_>
 106     pub(crate) is_infer_qualifier: bool,
 107 }
 108
 109 #[derive(Debug)]
 110 pub(super) struct PatternContext {
 111     pub(super) refutability: PatternRefutability,
 112     pub(super) param_ctx: Option<(ast::ParamList, ast::Param, ParamKind)>,
 113     pub(super) has_type_ascription: bool,
 114     pub(super) parent_pat: Option<ast::Pat>,
 115     pub(super) ref_token: Option<SyntaxToken>,
 116     pub(super) mut_token: Option<SyntaxToken>,
 117 }
 118
 119 #[derive(Debug)]
 120 pub(super) struct LifetimeContext {
 121     pub(super) lifetime: Option<ast::Lifetime>,
 122     pub(super) kind: LifetimeKind,
 123 }
 124
 125 #[derive(Debug)]
 126 pub(super) enum LifetimeKind {
 127     LifetimeParam { is_decl: bool, param: ast::LifetimeParam },
 128     Lifetime,
 129     LabelRef,
 130     LabelDef,
 131 }
 132
 133 #[derive(Debug)]
 134 pub(super) struct NameContext {
 135     #[allow(dead_code)]
 136     pub(super) name: Option<ast::Name>,
 137     pub(super) kind: NameKind,
 138 }
 139
 140 #[derive(Debug)]
 141 #[allow(dead_code)]
 142 pub(super) enum NameKind {
 143     Const,
 144     ConstParam,
 145     Enum,
 146     Function,
 147     IdentPat,
 148     MacroDef,
 149     MacroRules,
 150     /// Fake node
 151     Module(ast::Module),
 152     RecordField,
 153     Rename,
 154     SelfParam,
 155     Static,
 156     Struct,
 157     Trait,
 158     TypeAlias,
 159     TypeParam,
 160     Union,
 161     Variant,
 162 }
 163
 164 #[derive(Debug)]
 165 pub(super) struct NameRefContext {
 166     /// NameRef syntax in the original file
 167     pub(super) nameref: Option<ast::NameRef>,
 168     pub(super) dot_access: Option<DotAccess>,
 169     pub(super) path_ctx: Option<PathCompletionCtx>,
 170 }
 171
 172 #[derive(Debug)]
 173 pub(super) enum IdentContext {
 174     Name(NameContext),
 175     NameRef(NameRefContext),
 176     Lifetime(LifetimeContext),
 177     /// Original token, fake token
 178     String {
 179         original: ast::String,
 180         expanded: Option<ast::String>,
 181     },
 182     UnexpandedAttrTT {
 183         fake_attribute_under_caret: Option<ast::Attr>,
 184     },
 185 }
 186
 187 #[derive(Debug)]
 188 pub(super) enum DotAccess {
 189     Field {
 190         receiver: Option<ast::Expr>,
 191         /// True if the receiver is an integer and there is no ident in the original file after it yet
 192         /// like `0.$0`
 193         receiver_is_ambiguous_float_literal: bool,
 194     },
 195     Method {
 196         receiver: Option<ast::Expr>,
 197         has_parens: bool,
 198     },
 199 }
 200
 201 #[derive(Clone, Debug, PartialEq, Eq)]
 202 pub(crate) enum ParamKind {
 203     Function(ast::Fn),
 204     Closure(ast::ClosureExpr),
 205 }
 206
 207 /// `CompletionContext` is created early during completion to figure out, where
 208 /// exactly is the cursor, syntax-wise.
 209 #[derive(Debug)]
 210 pub(crate) struct CompletionContext<'a> {
 211     pub(super) sema: Semantics<'a, RootDatabase>,
 212     pub(super) scope: SemanticsScope<'a>,
 213     pub(super) db: &'a RootDatabase,
 214     pub(super) config: &'a CompletionConfig,
 215     pub(super) position: FilePosition,
 216
 217     /// The token before the cursor, in the original file.
 218     pub(super) original_token: SyntaxToken,
 219     /// The token before the cursor, in the macro-expanded file.
 220     pub(super) token: SyntaxToken,
 221     /// The crate of the current file.
 222     pub(super) krate: hir::Crate,
 223     /// The module of the `scope`.
 224     pub(super) module: hir::Module,
 225
 226     /// The expected name of what we are completing.
 227     /// This is usually the parameter name of the function argument we are completing.
 228     pub(super) expected_name: Option<NameOrNameRef>,
 229     /// The expected type of what we are completing.
 230     pub(super) expected_type: Option<Type>,
 231
 232     /// The parent function of the cursor position if it exists.
 233     pub(super) function_def: Option<ast::Fn>,
 234     /// The parent impl of the cursor position if it exists.
 235     pub(super) impl_def: Option<ast::Impl>,
 236     /// Are we completing inside a let statement with a missing semicolon?
 237     pub(super) incomplete_let: bool,
 238
 239     pub(super) completion_location: Option<ImmediateLocation>,
 240     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
 241     pub(super) previous_token: Option<SyntaxToken>,
 242
 243     pub(super) ident_ctx: IdentContext,
 244
 245     pub(super) pattern_ctx: Option<PatternContext>,
 246
 247     pub(super) existing_derives: FxHashSet<hir::Macro>,
 248
 249     pub(super) locals: FxHashMap<Name, Local>,
 250 }
 251
 252 impl<'a> CompletionContext<'a> {
 253     /// The range of the identifier that is being completed.
 254     pub(crate) fn source_range(&self) -> TextRange {
 255         // check kind of macro-expanded token, but use range of original token
 256         let kind = self.token.kind();
 257         match kind {
 258             CHAR => {
 259                 // assume we are completing a lifetime but the user has only typed the '
 260                 cov_mark::hit!(completes_if_lifetime_without_idents);
 261                 TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 262             }
 263             IDENT | LIFETIME_IDENT | UNDERSCORE => self.original_token.text_range(),
 264             _ if kind.is_keyword() => self.original_token.text_range(),
 265             _ => TextRange::empty(self.position.offset),
 266         }
 267     }
 268
 269     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 270         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 271     }
 272
 273     pub(crate) fn famous_defs(&self) -> FamousDefs {
 274         FamousDefs(&self.sema, self.krate)
 275     }
 276
 277     pub(super) fn nameref_ctx(&self) -> Option<&NameRefContext> {
 278         match &self.ident_ctx {
 279             IdentContext::NameRef(it) => Some(it),
 280             _ => None,
 281         }
 282     }
 283
 284     pub(super) fn name_ctx(&self) -> Option<&NameContext> {
 285         match &self.ident_ctx {
 286             IdentContext::Name(it) => Some(it),
 287             _ => None,
 288         }
 289     }
 290
 291     pub(super) fn lifetime_ctx(&self) -> Option<&LifetimeContext> {
 292         match &self.ident_ctx {
 293             IdentContext::Lifetime(it) => Some(it),
 294             _ => None,
 295         }
 296     }
 297
 298     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 299         match self.nameref_ctx() {
 300             Some(NameRefContext {
 301                 dot_access:
 302                     Some(DotAccess::Method { receiver, .. } | DotAccess::Field { receiver, .. }),
 303                 ..
 304             }) => receiver.as_ref(),
 305             _ => None,
 306         }
 307     }
 308
 309     pub(crate) fn has_dot_receiver(&self) -> bool {
 310         self.dot_receiver().is_some()
 311     }
 312
 313     pub(crate) fn expects_assoc_item(&self) -> bool {
 314         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 315     }
 316
 317     pub(crate) fn expects_variant(&self) -> bool {
 318         matches!(self.name_ctx(), Some(NameContext { kind: NameKind::Variant, .. }))
 319     }
 320
 321     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 322         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 323     }
 324
 325     pub(crate) fn expects_item(&self) -> bool {
 326         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 327     }
 328
 329     pub(crate) fn expects_generic_arg(&self) -> bool {
 330         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 331     }
 332
 333     pub(crate) fn has_block_expr_parent(&self) -> bool {
 334         matches!(self.completion_location, Some(ImmediateLocation::StmtList))
 335     }
 336
 337     pub(crate) fn expects_ident_ref_expr(&self) -> bool {
 338         matches!(self.completion_location, Some(ImmediateLocation::RefExpr))
 339     }
 340
 341     pub(crate) fn expect_field(&self) -> bool {
 342         matches!(self.completion_location, Some(ImmediateLocation::TupleField))
 343             || matches!(self.name_ctx(), Some(NameContext { kind: NameKind::RecordField, .. }))
 344     }
 345
 346     /// Whether the cursor is right after a trait or impl header.
 347     /// trait Foo ident$0
 348     // FIXME: This probably shouldn't exist
 349     pub(crate) fn has_unfinished_impl_or_trait_prev_sibling(&self) -> bool {
 350         matches!(
 351             self.prev_sibling,
 352             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 353         )
 354     }
 355
 356     // FIXME: This probably shouldn't exist
 357     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 358         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 359     }
 360
 361     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 362         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 363     }
 364
 365     pub(crate) fn after_if(&self) -> bool {
 366         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 367     }
 368
 369     // FIXME: This shouldn't exist
 370     pub(crate) fn is_path_disallowed(&self) -> bool {
 371         self.previous_token_is(T![unsafe])
 372             || matches!(
 373                 self.prev_sibling,
 374                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 375             )
 376             || matches!(
 377                 self.completion_location,
 378                 Some(ImmediateLocation::RecordPat(_) | ImmediateLocation::RecordExpr(_))
 379             )
 380             || matches!(
 381                 self.name_ctx(),
 382                 Some(NameContext { kind: NameKind::Module(_) | NameKind::Rename, .. })
 383             )
 384     }
 385
 386     pub(crate) fn path_context(&self) -> Option<&PathCompletionCtx> {
 387         self.nameref_ctx().and_then(|ctx| ctx.path_ctx.as_ref())
 388     }
 389
 390     pub(crate) fn expects_expression(&self) -> bool {
 391         matches!(self.path_context(), Some(PathCompletionCtx { kind: PathKind::Expr { .. }, .. }))
 392     }
 393
 394     pub(crate) fn expects_type(&self) -> bool {
 395         matches!(self.path_context(), Some(PathCompletionCtx { kind: PathKind::Type, .. }))
 396     }
 397
 398     pub(crate) fn path_is_call(&self) -> bool {
 399         self.path_context().map_or(false, |it| it.has_call_parens)
 400     }
 401
 402     pub(crate) fn is_non_trivial_path(&self) -> bool {
 403         matches!(
 404             self.path_context(),
 405             Some(
 406                 PathCompletionCtx { is_absolute_path: true, .. }
 407                     | PathCompletionCtx { qualifier: Some(_), .. }
 408             )
 409         )
 410     }
 411
 412     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 413         self.path_context().and_then(|it| it.qualifier.as_ref().map(|it| &it.path))
 414     }
 415
 416     pub(crate) fn path_kind(&self) -> Option<PathKind> {
 417         self.path_context().map(|it| it.kind)
 418     }
 419
 420     pub(crate) fn is_immediately_after_macro_bang(&self) -> bool {
 421         self.token.kind() == BANG && self.token.parent().map_or(false, |it| it.kind() == MACRO_CALL)
 422     }
 423
 424     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 425     pub(crate) fn is_visible<I>(&self, item: &I) -> Visible
 426     where
 427         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 428     {
 429         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 430     }
 431
 432     pub(crate) fn is_scope_def_hidden(&self, scope_def: ScopeDef) -> bool {
 433         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 434             return self.is_doc_hidden(&attrs, krate);
 435         }
 436
 437         false
 438     }
 439
 440     /// Check if an item is `#[doc(hidden)]`.
 441     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
 442         let attrs = item.attrs(self.db);
 443         let krate = item.krate(self.db);
 444         match (attrs, krate) {
 445             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
 446             _ => false,
 447         }
 448     }
 449     /// Whether the given trait is an operator trait or not.
 450     pub(crate) fn is_ops_trait(&self, trait_: hir::Trait) -> bool {
 451         match trait_.attrs(self.db).lang() {
 452             Some(lang) => OP_TRAIT_LANG_NAMES.contains(&lang.as_str()),
 453             None => false,
 454         }
 455     }
 456
 457     /// Returns the traits in scope, with the [`Drop`] trait removed.
 458     pub(crate) fn traits_in_scope(&self) -> hir::VisibleTraits {
 459         let mut traits_in_scope = self.scope.visible_traits();
 460         if let Some(drop) = self.famous_defs().core_ops_Drop() {
 461             traits_in_scope.0.remove(&drop.into());
 462         }
 463         traits_in_scope
 464     }
 465
 466     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 467     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 468         let _p = profile::span("CompletionContext::process_all_names");
 469         self.scope.process_all_names(&mut |name, def| {
 470             if self.is_scope_def_hidden(def) {
 471                 return;
 472             }
 473
 474             f(name, def);
 475         });
 476     }
 477
 478     pub(crate) fn process_all_names_raw(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 479         let _p = profile::span("CompletionContext::process_all_names_raw");
 480         self.scope.process_all_names(&mut |name, def| f(name, def));
 481     }
 482
 483     fn is_visible_impl(
 484         &self,
 485         vis: &hir::Visibility,
 486         attrs: &hir::Attrs,
 487         defining_crate: hir::Crate,
 488     ) -> Visible {
 489         if !vis.is_visible_from(self.db, self.module.into()) {
 490             if !self.config.enable_private_editable {
 491                 return Visible::No;
 492             }
 493             // If the definition location is editable, also show private items
 494             let root_file = defining_crate.root_file(self.db);
 495             let source_root_id = self.db.file_source_root(root_file);
 496             let is_editable = !self.db.source_root(source_root_id).is_library;
 497             return if is_editable { Visible::Editable } else { Visible::No };
 498         }
 499
 500         if self.is_doc_hidden(attrs, defining_crate) {
 501             Visible::No
 502         } else {
 503             Visible::Yes
 504         }
 505     }
 506
 507     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 508         // `doc(hidden)` items are only completed within the defining crate.
 509         self.krate != defining_crate && attrs.has_doc_hidden()
 510     }
 511 }
 512
 513 // CompletionContext construction
 514 impl<'a> CompletionContext<'a> {
 515     pub(super) fn new(
 516         db: &'a RootDatabase,
 517         position @ FilePosition { file_id, offset }: FilePosition,
 518         config: &'a CompletionConfig,
 519     ) -> Option<CompletionContext<'a>> {
 520         let _p = profile::span("CompletionContext::new");
 521         let sema = Semantics::new(db);
 522
 523         let original_file = sema.parse(file_id);
 524
 525         // Insert a fake ident to get a valid parse tree. We will use this file
 526         // to determine context, though the original_file will be used for
 527         // actual completion.
 528         let file_with_fake_ident = {
 529             let parse = db.parse(file_id);
 530             let edit = Indel::insert(offset, COMPLETION_MARKER.to_string());
 531             parse.reparse(&edit).tree()
 532         };
 533         let fake_ident_token =
 534             file_with_fake_ident.syntax().token_at_offset(offset).right_biased()?;
 535
 536         let original_token = original_file.syntax().token_at_offset(offset).left_biased()?;
 537         let token = sema.descend_into_macros_single(original_token.clone());
 538         let scope = sema.scope_at_offset(&token.parent()?, offset)?;
 539         let krate = scope.krate();
 540         let module = scope.module();
 541
 542         let mut locals = FxHashMap::default();
 543         scope.process_all_names(&mut |name, scope| {
 544             if let ScopeDef::Local(local) = scope {
 545                 locals.insert(name, local);
 546             }
 547         });
 548
 549         let mut ctx = CompletionContext {
 550             sema,
 551             scope,
 552             db,
 553             config,
 554             position,
 555             original_token,
 556             token,
 557             krate,
 558             module,
 559             expected_name: None,
 560             expected_type: None,
 561             function_def: None,
 562             impl_def: None,
 563             incomplete_let: false,
 564             completion_location: None,
 565             prev_sibling: None,
 566             previous_token: None,
 567             // dummy value, will be overwritten
 568             ident_ctx: IdentContext::UnexpandedAttrTT { fake_attribute_under_caret: None },
 569             pattern_ctx: None,
 570             existing_derives: Default::default(),
 571             locals,
 572         };
 573         ctx.expand_and_fill(
 574             original_file.syntax().clone(),
 575             file_with_fake_ident.syntax().clone(),
 576             offset,
 577             fake_ident_token,
 578         )?;
 579         Some(ctx)
 580     }
 581
 582     /// Expand attributes and macro calls at the current cursor position for both the original file
 583     /// and fake file repeatedly. As soon as one of the two expansions fail we stop so the original
 584     /// and speculative states stay in sync.
 585     fn expand_and_fill(
 586         &mut self,
 587         mut original_file: SyntaxNode,
 588         mut speculative_file: SyntaxNode,
 589         mut offset: TextSize,
 590         mut fake_ident_token: SyntaxToken,
 591     ) -> Option<()> {
 592         let _p = profile::span("CompletionContext::expand_and_fill");
 593         let mut derive_ctx = None;
 594
 595         'expansion: loop {
 596             let parent_item =
 597                 |item: &ast::Item| item.syntax().ancestors().skip(1).find_map(ast::Item::cast);
 598             let ancestor_items = iter::successors(
 599                 Option::zip(
 600                     find_node_at_offset::<ast::Item>(&original_file, offset),
 601                     find_node_at_offset::<ast::Item>(&speculative_file, offset),
 602                 ),
 603                 |(a, b)| parent_item(a).zip(parent_item(b)),
 604             );
 605
 606             // first try to expand attributes as these are always the outermost macro calls
 607             'ancestors: for (actual_item, item_with_fake_ident) in ancestor_items {
 608                 match (
 609                     self.sema.expand_attr_macro(&actual_item),
 610                     self.sema.speculative_expand_attr_macro(
 611                         &actual_item,
 612                         &item_with_fake_ident,
 613                         fake_ident_token.clone(),
 614                     ),
 615                 ) {
 616                     // maybe parent items have attributes, so continue walking the ancestors
 617                     (None, None) => continue 'ancestors,
 618                     // successful expansions
 619                     (Some(actual_expansion), Some((fake_expansion, fake_mapped_token))) => {
 620                         let new_offset = fake_mapped_token.text_range().start();
 621                         if new_offset > actual_expansion.text_range().end() {
 622                             // offset outside of bounds from the original expansion,
 623                             // stop here to prevent problems from happening
 624                             break 'expansion;
 625                         }
 626                         original_file = actual_expansion;
 627                         speculative_file = fake_expansion;
 628                         fake_ident_token = fake_mapped_token;
 629                         offset = new_offset;
 630                         continue 'expansion;
 631                     }
 632                     // exactly one expansion failed, inconsistent state so stop expanding completely
 633                     _ => break 'expansion,
 634                 }
 635             }
 636
 637             // No attributes have been expanded, so look for macro_call! token trees or derive token trees
 638             let orig_tt = match find_node_at_offset::<ast::TokenTree>(&original_file, offset) {
 639                 Some(it) => it,
 640                 None => break 'expansion,
 641             };
 642             let spec_tt = match find_node_at_offset::<ast::TokenTree>(&speculative_file, offset) {
 643                 Some(it) => it,
 644                 None => break 'expansion,
 645             };
 646
 647             // Expand pseudo-derive expansion
 648             if let (Some(orig_attr), Some(spec_attr)) = (
 649                 orig_tt.syntax().parent().and_then(ast::Meta::cast).and_then(|it| it.parent_attr()),
 650                 spec_tt.syntax().parent().and_then(ast::Meta::cast).and_then(|it| it.parent_attr()),
 651             ) {
 652                 if let (Some(actual_expansion), Some((fake_expansion, fake_mapped_token))) = (
 653                     self.sema.expand_derive_as_pseudo_attr_macro(&orig_attr),
 654                     self.sema.speculative_expand_derive_as_pseudo_attr_macro(
 655                         &orig_attr,
 656                         &spec_attr,
 657                         fake_ident_token.clone(),
 658                     ),
 659                 ) {
 660                     derive_ctx = Some((
 661                         actual_expansion,
 662                         fake_expansion,
 663                         fake_mapped_token.text_range().start(),
 664                         orig_attr,
 665                     ));
 666                 }
 667                 // at this point we won't have any more successful expansions, so stop
 668                 break 'expansion;
 669             }
 670
 671             // Expand fn-like macro calls
 672             if let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 673                 orig_tt.syntax().ancestors().find_map(ast::MacroCall::cast),
 674                 spec_tt.syntax().ancestors().find_map(ast::MacroCall::cast),
 675             ) {
 676                 let mac_call_path0 = actual_macro_call.path().as_ref().map(|s| s.syntax().text());
 677                 let mac_call_path1 =
 678                     macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text());
 679
 680                 // inconsistent state, stop expanding
 681                 if mac_call_path0 != mac_call_path1 {
 682                     break 'expansion;
 683                 }
 684                 let speculative_args = match macro_call_with_fake_ident.token_tree() {
 685                     Some(tt) => tt,
 686                     None => break 'expansion,
 687                 };
 688
 689                 match (
 690                     self.sema.expand(&actual_macro_call),
 691                     self.sema.speculative_expand(
 692                         &actual_macro_call,
 693                         &speculative_args,
 694                         fake_ident_token.clone(),
 695                     ),
 696                 ) {
 697                     // successful expansions
 698                     (Some(actual_expansion), Some((fake_expansion, fake_mapped_token))) => {
 699                         let new_offset = fake_mapped_token.text_range().start();
 700                         if new_offset > actual_expansion.text_range().end() {
 701                             // offset outside of bounds from the original expansion,
 702                             // stop here to prevent problems from happening
 703                             break 'expansion;
 704                         }
 705                         original_file = actual_expansion;
 706                         speculative_file = fake_expansion;
 707                         fake_ident_token = fake_mapped_token;
 708                         offset = new_offset;
 709                         continue 'expansion;
 710                     }
 711                     // at least on expansion failed, we won't have anything to expand from this point
 712                     // onwards so break out
 713                     _ => break 'expansion,
 714                 }
 715             }
 716
 717             // none of our states have changed so stop the loop
 718             break 'expansion;
 719         }
 720
 721         self.fill(&original_file, speculative_file, offset, derive_ctx)
 722     }
 723
 724     /// Calculate the expected type and name of the cursor position.
 725     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 726         let mut node = match self.token.parent() {
 727             Some(it) => it,
 728             None => return (None, None),
 729         };
 730         loop {
 731             break match_ast! {
 732                 match node {
 733                     ast::LetStmt(it) => {
 734                         cov_mark::hit!(expected_type_let_with_leading_char);
 735                         cov_mark::hit!(expected_type_let_without_leading_char);
 736                         let ty = it.pat()
 737                             .and_then(|pat| self.sema.type_of_pat(&pat))
 738                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)))
 739                             .map(TypeInfo::original);
 740                         let name = match it.pat() {
 741                             Some(ast::Pat::IdentPat(ident)) => ident.name().map(NameOrNameRef::Name),
 742                             Some(_) | None => None,
 743                         };
 744
 745                         (ty, name)
 746                     },
 747                     ast::LetExpr(it) => {
 748                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 749                         let ty = it.pat()
 750                             .and_then(|pat| self.sema.type_of_pat(&pat))
 751                             .or_else(|| it.expr().and_then(|it| self.sema.type_of_expr(&it)))
 752                             .map(TypeInfo::original);
 753                         (ty, None)
 754                     },
 755                     ast::ArgList(_) => {
 756                         cov_mark::hit!(expected_type_fn_param);
 757                         ActiveParameter::at_token(
 758                             &self.sema,
 759                             self.token.clone(),
 760                         ).map(|ap| {
 761                             let name = ap.ident().map(NameOrNameRef::Name);
 762                             let ty = if has_ref(&self.token) {
 763                                 cov_mark::hit!(expected_type_fn_param_ref);
 764                                 ap.ty.remove_ref()
 765                             } else {
 766                                 Some(ap.ty)
 767                             };
 768                             (ty, name)
 769                         })
 770                         .unwrap_or((None, None))
 771                     },
 772                     ast::RecordExprFieldList(it) => {
 773                         // wouldn't try {} be nice...
 774                         (|| {
 775                             if self.token.kind() == T![..]
 776                                 || self.token.prev_token().map(|t| t.kind()) == Some(T![..])
 777                             {
 778                                 cov_mark::hit!(expected_type_struct_func_update);
 779                                 let record_expr = it.syntax().parent().and_then(ast::RecordExpr::cast)?;
 780                                 let ty = self.sema.type_of_expr(&record_expr.into())?;
 781                                 Some((
 782                                     Some(ty.original),
 783                                     None
 784                                 ))
 785                             } else {
 786                                 cov_mark::hit!(expected_type_struct_field_without_leading_char);
 787                                 let expr_field = self.token.prev_sibling_or_token()?
 788                                     .into_node()
 789                                     .and_then(ast::RecordExprField::cast)?;
 790                                 let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 791                                 Some((
 792                                     Some(ty),
 793                                     expr_field.field_name().map(NameOrNameRef::NameRef),
 794                                 ))
 795                             }
 796                         })().unwrap_or((None, None))
 797                     },
 798                     ast::RecordExprField(it) => {
 799                         if let Some(expr) = it.expr() {
 800                             cov_mark::hit!(expected_type_struct_field_with_leading_char);
 801                             (
 802                                 self.sema.type_of_expr(&expr).map(TypeInfo::original),
 803                                 it.field_name().map(NameOrNameRef::NameRef),
 804                             )
 805                         } else {
 806                             cov_mark::hit!(expected_type_struct_field_followed_by_comma);
 807                             let ty = self.sema.resolve_record_field(&it)
 808                                 .map(|(_, _, ty)| ty);
 809                             (
 810                                 ty,
 811                                 it.field_name().map(NameOrNameRef::NameRef),
 812                             )
 813                         }
 814                     },
 815                     ast::MatchExpr(it) => {
 816                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 817                         let ty = it.expr().and_then(|e| self.sema.type_of_expr(&e)).map(TypeInfo::original);
 818                         (ty, None)
 819                     },
 820                     ast::IfExpr(it) => {
 821                         let ty = it.condition()
 822                             .and_then(|e| self.sema.type_of_expr(&e))
 823                             .map(TypeInfo::original);
 824                         (ty, None)
 825                     },
 826                     ast::IdentPat(it) => {
 827                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 828                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 829                         let ty = self.sema.type_of_pat(&ast::Pat::from(it)).map(TypeInfo::original);
 830                         (ty, None)
 831                     },
 832                     ast::Fn(it) => {
 833                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 834                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 835                         let def = self.sema.to_def(&it);
 836                         (def.map(|def| def.ret_type(self.db)), None)
 837                     },
 838                     ast::ClosureExpr(it) => {
 839                         let ty = self.sema.type_of_expr(&it.into());
 840                         ty.and_then(|ty| ty.original.as_callable(self.db))
 841                             .map(|c| (Some(c.return_type()), None))
 842                             .unwrap_or((None, None))
 843                     },
 844                     ast::ParamList(_) => (None, None),
 845                     ast::Stmt(_) => (None, None),
 846                     ast::Item(_) => (None, None),
 847                     _ => {
 848                         match node.parent() {
 849                             Some(n) => {
 850                                 node = n;
 851                                 continue;
 852                             },
 853                             None => (None, None),
 854                         }
 855                     },
 856                 }
 857             };
 858         }
 859     }
 860
 861     /// Fill the completion context, this is what does semantic reasoning about the surrounding context
 862     /// of the completion location.
 863     fn fill(
 864         &mut self,
 865         original_file: &SyntaxNode,
 866         file_with_fake_ident: SyntaxNode,
 867         offset: TextSize,
 868         derive_ctx: Option<(SyntaxNode, SyntaxNode, TextSize, ast::Attr)>,
 869     ) -> Option<()> {
 870         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 871         let syntax_element = NodeOrToken::Token(fake_ident_token);
 872         if is_in_token_of_for_loop(syntax_element.clone()) {
 873             // for pat $0
 874             // there is nothing to complete here except `in` keyword
 875             // don't bother populating the context
 876             // FIXME: the completion calculations should end up good enough
 877             // such that this special case becomes unnecessary
 878             return None;
 879         }
 880
 881         self.previous_token = previous_token(syntax_element.clone());
 882
 883         self.incomplete_let =
 884             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 885                 it.syntax().text_range().end() == syntax_element.text_range().end()
 886             });
 887
 888         (self.expected_type, self.expected_name) = self.expected_type_and_name();
 889
 890         // Overwrite the path kind for derives
 891         if let Some((original_file, file_with_fake_ident, offset, origin_attr)) = derive_ctx {
 892             self.existing_derives = self
 893                 .sema
 894                 .resolve_derive_macro(&origin_attr)
 895                 .into_iter()
 896                 .flatten()
 897                 .flatten()
 898                 .collect();
 899
 900             if let Some(ast::NameLike::NameRef(name_ref)) =
 901                 find_node_at_offset(&file_with_fake_ident, offset)
 902             {
 903                 let parent = name_ref.syntax().parent()?;
 904                 let (mut nameref_ctx, _) =
 905                     Self::classify_name_ref(&self.sema, &original_file, name_ref, parent);
 906                 if let Some(path_ctx) = &mut nameref_ctx.path_ctx {
 907                     path_ctx.kind = PathKind::Derive;
 908                 }
 909                 self.ident_ctx = IdentContext::NameRef(nameref_ctx);
 910                 return Some(());
 911             }
 912             return None;
 913         }
 914
 915         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 916             Some(it) => it,
 917             None => {
 918                 if let Some(original) = ast::String::cast(self.original_token.clone()) {
 919                     self.ident_ctx = IdentContext::String {
 920                         original,
 921                         expanded: ast::String::cast(self.token.clone()),
 922                     };
 923                 } else {
 924                     // Fix up trailing whitespace problem
 925                     // #[attr(foo = $0
 926                     let token = if self.token.kind() == SyntaxKind::WHITESPACE {
 927                         self.previous_token.as_ref()?
 928                     } else {
 929                         &self.token
 930                     };
 931                     let p = token.parent()?;
 932                     if p.kind() == SyntaxKind::TOKEN_TREE
 933                         && p.ancestors().any(|it| it.kind() == SyntaxKind::META)
 934                     {
 935                         self.ident_ctx = IdentContext::UnexpandedAttrTT {
 936                             fake_attribute_under_caret: syntax_element
 937                                 .ancestors()
 938                                 .find_map(ast::Attr::cast),
 939                         };
 940                     } else {
 941                         return None;
 942                     }
 943                 }
 944                 return Some(());
 945             }
 946         };
 947         self.completion_location =
 948             determine_location(&self.sema, original_file, offset, &name_like);
 949         self.prev_sibling = determine_prev_sibling(&name_like);
 950         self.impl_def = self
 951             .sema
 952             .token_ancestors_with_macros(self.token.clone())
 953             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 954             .find_map(ast::Impl::cast);
 955         self.function_def = self
 956             .sema
 957             .token_ancestors_with_macros(self.token.clone())
 958             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 959             .find_map(ast::Fn::cast);
 960
 961         match name_like {
 962             ast::NameLike::Lifetime(lifetime) => {
 963                 self.ident_ctx = IdentContext::Lifetime(Self::classify_lifetime(
 964                     &self.sema,
 965                     original_file,
 966                     lifetime,
 967                 )?);
 968             }
 969             ast::NameLike::NameRef(name_ref) => {
 970                 let parent = name_ref.syntax().parent()?;
 971                 let (nameref_ctx, pat_ctx) =
 972                     Self::classify_name_ref(&self.sema, &original_file, name_ref, parent);
 973                 self.ident_ctx = IdentContext::NameRef(nameref_ctx);
 974                 self.pattern_ctx = pat_ctx;
 975             }
 976             ast::NameLike::Name(name) => {
 977                 let (name_ctx, pat_ctx) = Self::classify_name(&self.sema, original_file, name)?;
 978                 self.pattern_ctx = pat_ctx;
 979                 self.ident_ctx = IdentContext::Name(name_ctx);
 980             }
 981         }
 982         Some(())
 983     }
 984
 985     fn classify_lifetime(
 986         _sema: &Semantics<RootDatabase>,
 987         original_file: &SyntaxNode,
 988         lifetime: ast::Lifetime,
 989     ) -> Option<LifetimeContext> {
 990         let parent = lifetime.syntax().parent()?;
 991         if parent.kind() == ERROR {
 992             return None;
 993         }
 994
 995         let kind = match_ast! {
 996             match parent {
 997                 ast::LifetimeParam(param) => LifetimeKind::LifetimeParam {
 998                     is_decl: param.lifetime().as_ref() == Some(&lifetime),
 999                     param
1000                 },
1001                 ast::BreakExpr(_) => LifetimeKind::LabelRef,
1002                 ast::ContinueExpr(_) => LifetimeKind::LabelRef,
1003                 ast::Label(_) => LifetimeKind::LabelDef,
1004                 _ => LifetimeKind::Lifetime,
1005             }
1006         };
1007         let lifetime = find_node_at_offset(&original_file, lifetime.syntax().text_range().start());
1008
1009         Some(LifetimeContext { lifetime, kind })
1010     }
1011
1012     fn classify_name(
1013         _sema: &Semantics<RootDatabase>,
1014         original_file: &SyntaxNode,
1015         name: ast::Name,
1016     ) -> Option<(NameContext, Option<PatternContext>)> {
1017         let parent = name.syntax().parent()?;
1018         let mut pat_ctx = None;
1019         let kind = match_ast! {
1020             match parent {
1021                 ast::Const(_) => NameKind::Const,
1022                 ast::ConstParam(_) => NameKind::ConstParam,
1023                 ast::Enum(_) => NameKind::Enum,
1024                 ast::Fn(_) => NameKind::Function,
1025                 ast::IdentPat(bind_pat) => {
1026                     let is_name_in_field_pat = bind_pat
1027                         .syntax()
1028                         .parent()
1029                         .and_then(ast::RecordPatField::cast)
1030                         .map_or(false, |pat_field| pat_field.name_ref().is_none());
1031                     if !is_name_in_field_pat {
1032                         pat_ctx = Some(pattern_context_for(original_file, bind_pat.into()));
1033                     }
1034
1035                     NameKind::IdentPat
1036                 },
1037                 ast::MacroDef(_) => NameKind::MacroDef,
1038                 ast::MacroRules(_) => NameKind::MacroRules,
1039                 ast::Module(module) => NameKind::Module(module),
1040                 ast::RecordField(_) => NameKind::RecordField,
1041                 ast::Rename(_) => NameKind::Rename,
1042                 ast::SelfParam(_) => NameKind::SelfParam,
1043                 ast::Static(_) => NameKind::Static,
1044                 ast::Struct(_) => NameKind::Struct,
1045                 ast::Trait(_) => NameKind::Trait,
1046                 ast::TypeAlias(_) => NameKind::TypeAlias,
1047                 ast::TypeParam(_) => NameKind::TypeParam,
1048                 ast::Union(_) => NameKind::Union,
1049                 ast::Variant(_) => NameKind::Variant,
1050                 _ => return None,
1051             }
1052         };
1053         let name = find_node_at_offset(&original_file, name.syntax().text_range().start());
1054         Some((NameContext { name, kind }, pat_ctx))
1055     }
1056
1057     fn classify_name_ref(
1058         sema: &Semantics<RootDatabase>,
1059         original_file: &SyntaxNode,
1060         name_ref: ast::NameRef,
1061         parent: SyntaxNode,
1062     ) -> (NameRefContext, Option<PatternContext>) {
1063         let nameref = find_node_at_offset(&original_file, name_ref.syntax().text_range().start());
1064
1065         let mut nameref_ctx = NameRefContext { dot_access: None, path_ctx: None, nameref };
1066
1067         let segment = match_ast! {
1068             match parent {
1069                 ast::PathSegment(segment) => segment,
1070                 ast::FieldExpr(field) => {
1071                     let receiver = find_in_original_file(field.expr(), original_file);
1072                     let receiver_is_ambiguous_float_literal = match &receiver {
1073                         Some(ast::Expr::Literal(l)) => matches! {
1074                             l.kind(),
1075                             ast::LiteralKind::FloatNumber { .. } if l.syntax().last_token().map_or(false, |it| it.kind() == T![.])
1076                         },
1077                         _ => false,
1078                     };
1079                     nameref_ctx.dot_access = Some(DotAccess::Field { receiver, receiver_is_ambiguous_float_literal });
1080                     return (nameref_ctx, None);
1081                 },
1082                 ast::MethodCallExpr(method) => {
1083                     nameref_ctx.dot_access = Some(
1084                         DotAccess::Method {
1085                             receiver: find_in_original_file(method.receiver(), original_file),
1086                             has_parens: method.arg_list().map_or(false, |it| it.l_paren_token().is_some())
1087                         }
1088                     );
1089                     return (nameref_ctx, None);
1090                 },
1091                 _ => return (nameref_ctx, None),
1092             }
1093         };
1094
1095         let path = segment.parent_path();
1096         let mut path_ctx = PathCompletionCtx {
1097             has_call_parens: false,
1098             has_macro_bang: false,
1099             is_absolute_path: false,
1100             qualifier: None,
1101             parent: path.parent_path(),
1102             kind: PathKind::Item { kind: ItemListKind::SourceFile },
1103             has_type_args: false,
1104         };
1105         let mut pat_ctx = None;
1106
1107         let is_in_block = |it: &SyntaxNode| {
1108             it.parent()
1109                 .map(|node| {
1110                     ast::ExprStmt::can_cast(node.kind()) || ast::StmtList::can_cast(node.kind())
1111                 })
1112                 .unwrap_or(false)
1113         };
1114
1115         let kind = path.syntax().ancestors().find_map(|it| {
1116             // using Option<Option<PathKind>> as extra controlflow
1117             let kind = match_ast! {
1118                 match it {
1119                     ast::PathType(_) => Some(PathKind::Type),
1120                     ast::PathExpr(it) => {
1121                         path_ctx.has_call_parens = it.syntax().parent().map_or(false, |it| ast::CallExpr::can_cast(it.kind()));
1122                         let in_block_expr = is_in_block(it.syntax());
1123                         let in_loop_body = is_in_loop_body(it.syntax());
1124
1125                         Some(PathKind::Expr { in_block_expr, in_loop_body })
1126                     },
1127                     ast::TupleStructPat(it) => {
1128                         path_ctx.has_call_parens = true;
1129                         pat_ctx = Some(pattern_context_for(original_file, it.into()));
1130                         Some(PathKind::Pat)
1131                     },
1132                     ast::RecordPat(it) => {
1133                         path_ctx.has_call_parens = true;
1134                         pat_ctx = Some(pattern_context_for(original_file, it.into()));
1135                         Some(PathKind::Pat)
1136                     },
1137                     ast::PathPat(it) => {
1138                         pat_ctx = Some(pattern_context_for(original_file, it.into()));
1139                         Some(PathKind::Pat)
1140                     },
1141                     ast::MacroCall(it) => {
1142                         path_ctx.has_macro_bang = it.excl_token().is_some();
1143                         let parent = it.syntax().parent();
1144                         match parent.as_ref().map(|it| it.kind()) {
1145                             Some(SyntaxKind::MACRO_PAT) => Some(PathKind::Pat),
1146                             Some(SyntaxKind::MACRO_TYPE) => Some(PathKind::Type),
1147                             Some(SyntaxKind::ITEM_LIST) => Some(PathKind::Item { kind: ItemListKind::Module }),
1148                             Some(SyntaxKind::ASSOC_ITEM_LIST) => Some(PathKind::Item { kind: match parent.and_then(|it| it.parent()).map(|it| it.kind()) {
1149                                 Some(SyntaxKind::TRAIT) => ItemListKind::Trait,
1150                                 Some(SyntaxKind::IMPL) => ItemListKind::Impl,
1151                                 _ => return Some(None),
1152                             } }),
1153                             Some(SyntaxKind::EXTERN_ITEM_LIST) => Some(PathKind::Item { kind: ItemListKind::ExternBlock }),
1154                             Some(SyntaxKind::SOURCE_FILE) => Some(PathKind::Item { kind: ItemListKind::SourceFile }),
1155                             _ => {
1156                                return Some(parent.and_then(ast::MacroExpr::cast).map(|it| {
1157                                     let in_loop_body = is_in_loop_body(it.syntax());
1158                                     let in_block_expr = is_in_block(it.syntax());
1159                                     PathKind::Expr { in_block_expr, in_loop_body }
1160                                 }));
1161                             },
1162                         }
1163                     },
1164                     ast::Meta(meta) => (|| {
1165                         let attr = meta.parent_attr()?;
1166                         let kind = attr.kind();
1167                         let attached = attr.syntax().parent()?;
1168                         let is_trailing_outer_attr = kind != AttrKind::Inner
1169                             && non_trivia_sibling(attr.syntax().clone().into(), syntax::Direction::Next).is_none();
1170                         let annotated_item_kind = if is_trailing_outer_attr {
1171                             None
1172                         } else {
1173                             Some(attached.kind())
1174                         };
1175                         Some(PathKind::Attr {
1176                             kind,
1177                             annotated_item_kind,
1178                         })
1179                     })(),
1180                     ast::Visibility(it) => Some(PathKind::Vis { has_in_token: it.in_token().is_some() }),
1181                     ast::UseTree(_) => Some(PathKind::Use),
1182                     ast::ItemList(_) => Some(PathKind::Item { kind: ItemListKind::Module }),
1183                     ast::AssocItemList(it) => Some(PathKind::Item { kind: {
1184                             match it.syntax().parent()?.kind() {
1185                                 SyntaxKind::TRAIT => ItemListKind::Trait,
1186                                 SyntaxKind::IMPL => ItemListKind::Impl,
1187                                 _ => return None,
1188                             }
1189                         }}),
1190                     ast::ExternItemList(_) => Some(PathKind::Item { kind: ItemListKind::ExternBlock }),
1191                     ast::SourceFile(_) => Some(PathKind::Item { kind: ItemListKind::SourceFile }),
1192                     _ => return None,
1193                 }
1194             };
1195             Some(kind)
1196         }).flatten();
1197         match kind {
1198             Some(kind) => path_ctx.kind = kind,
1199             None => return (nameref_ctx, pat_ctx),
1200         }
1201         path_ctx.has_type_args = segment.generic_arg_list().is_some();
1202
1203         if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
1204             if !use_tree_parent {
1205                 path_ctx.is_absolute_path =
1206                     path.top_path().segment().map_or(false, |it| it.coloncolon_token().is_some());
1207             }
1208
1209             let path = path
1210                 .segment()
1211                 .and_then(|it| find_node_in_file(original_file, &it))
1212                 .map(|it| it.parent_path());
1213             path_ctx.qualifier = path.map(|path| {
1214                 let res = sema.resolve_path(&path);
1215                 let is_super_chain = iter::successors(Some(path.clone()), |p| p.qualifier())
1216                     .all(|p| p.segment().and_then(|s| s.super_token()).is_some());
1217
1218                 // `<_>::$0`
1219                 let is_infer_qualifier = path.qualifier().is_none()
1220                     && matches!(
1221                         path.segment().and_then(|it| it.kind()),
1222                         Some(ast::PathSegmentKind::Type {
1223                             type_ref: Some(ast::Type::InferType(_)),
1224                             trait_ref: None,
1225                         })
1226                     );
1227
1228                 PathQualifierCtx {
1229                     path,
1230                     resolution: res,
1231                     is_super_chain,
1232                     use_tree_parent,
1233                     is_infer_qualifier,
1234                 }
1235             });
1236         } else if let Some(segment) = path.segment() {
1237             if segment.coloncolon_token().is_some() {
1238                 path_ctx.is_absolute_path = true;
1239             }
1240         }
1241         nameref_ctx.path_ctx = Some(path_ctx);
1242         (nameref_ctx, pat_ctx)
1243     }
1244 }
1245
1246 fn pattern_context_for(original_file: &SyntaxNode, pat: ast::Pat) -> PatternContext {
1247     let mut is_param = None;
1248     let (refutability, has_type_ascription) =
1249     pat
1250         .syntax()
1251         .ancestors()
1252         .skip_while(|it| ast::Pat::can_cast(it.kind()))
1253         .next()
1254         .map_or((PatternRefutability::Irrefutable, false), |node| {
1255             let refutability = match_ast! {
1256                 match node {
1257                     ast::LetStmt(let_) => return (PatternRefutability::Irrefutable, let_.ty().is_some()),
1258                     ast::Param(param) => {
1259                         let has_type_ascription = param.ty().is_some();
1260                         is_param = (|| {
1261                             let fake_param_list = param.syntax().parent().and_then(ast::ParamList::cast)?;
1262                             let param_list = find_node_in_file_compensated(original_file, &fake_param_list)?;
1263                             let param_list_owner = param_list.syntax().parent()?;
1264                             let kind = match_ast! {
1265                                 match param_list_owner {
1266                                     ast::ClosureExpr(closure) => ParamKind::Closure(closure),
1267                                     ast::Fn(fn_) => ParamKind::Function(fn_),
1268                                     _ => return None,
1269                                 }
1270                             };
1271                             Some((param_list, param, kind))
1272                         })();
1273                         return (PatternRefutability::Irrefutable, has_type_ascription)
1274                     },
1275                     ast::MatchArm(_) => PatternRefutability::Refutable,
1276                     ast::LetExpr(_) => PatternRefutability::Refutable,
1277                     ast::ForExpr(_) => PatternRefutability::Irrefutable,
1278                     _ => PatternRefutability::Irrefutable,
1279                 }
1280             };
1281             (refutability, false)
1282         });
1283     let (ref_token, mut_token) = match &pat {
1284         ast::Pat::IdentPat(it) => (it.ref_token(), it.mut_token()),
1285         _ => (None, None),
1286     };
1287     PatternContext {
1288         refutability,
1289         param_ctx: is_param,
1290         has_type_ascription,
1291         parent_pat: pat.syntax().parent().and_then(ast::Pat::cast),
1292         mut_token,
1293         ref_token,
1294     }
1295 }
1296
1297 fn find_in_original_file<N: AstNode>(x: Option<N>, original_file: &SyntaxNode) -> Option<N> {
1298     fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
1299         let range = syntax.text_range().intersect(range)?;
1300         syntax.covering_element(range).ancestors().find_map(N::cast)
1301     }
1302     x.map(|e| e.syntax().text_range()).and_then(|r| find_node_with_range(original_file, r))
1303 }
1304
1305 /// Attempts to find `node` inside `syntax` via `node`'s text range.
1306 fn find_node_in_file<N: AstNode>(syntax: &SyntaxNode, node: &N) -> Option<N> {
1307     let syntax_range = syntax.text_range();
1308     let range = node.syntax().text_range();
1309     let intersection = range.intersect(syntax_range)?;
1310     syntax.covering_element(intersection).ancestors().find_map(N::cast)
1311 }
1312
1313 /// Attempts to find `node` inside `syntax` via `node`'s text range while compensating
1314 /// for the offset introduced by the fake ident.
1315 /// This is wrong if `node` comes before the insertion point! Use `find_node_in_file` instead.
1316 fn find_node_in_file_compensated<N: AstNode>(syntax: &SyntaxNode, node: &N) -> Option<N> {
1317     let syntax_range = syntax.text_range();
1318     let range = node.syntax().text_range();
1319     let end = range.end().checked_sub(TextSize::try_from(COMPLETION_MARKER.len()).ok()?)?;
1320     if end < range.start() {
1321         return None;
1322     }
1323     let range = TextRange::new(range.start(), end);
1324     // our inserted ident could cause `range` to be go outside of the original syntax, so cap it
1325     let intersection = range.intersect(syntax_range)?;
1326     syntax.covering_element(intersection).ancestors().find_map(N::cast)
1327 }
1328
1329 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
1330     if let Some(qual) = path.qualifier() {
1331         return Some((qual, false));
1332     }
1333     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
1334     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
1335     Some((use_tree.path()?, true))
1336 }
1337
1338 fn has_ref(token: &SyntaxToken) -> bool {
1339     let mut token = token.clone();
1340     for skip in [IDENT, WHITESPACE, T![mut]] {
1341         if token.kind() == skip {
1342             token = match token.prev_token() {
1343                 Some(it) => it,
1344                 None => return false,
1345             }
1346         }
1347     }
1348     token.kind() == T![&]
1349 }
1350
1351 const OP_TRAIT_LANG_NAMES: &[&str] = &[
1352     "add_assign",
1353     "add",
1354     "bitand_assign",
1355     "bitand",
1356     "bitor_assign",
1357     "bitor",
1358     "bitxor_assign",
1359     "bitxor",
1360     "deref_mut",
1361     "deref",
1362     "div_assign",
1363     "div",
1364     "eq",
1365     "fn_mut",
1366     "fn_once",
1367     "fn",
1368     "index_mut",
1369     "index",
1370     "mul_assign",
1371     "mul",
1372     "neg",
1373     "not",
1374     "partial_ord",
1375     "rem_assign",
1376     "rem",
1377     "shl_assign",
1378     "shl",
1379     "shr_assign",
1380     "shr",
1381     "sub",
1382 ];
1383
1384 #[cfg(test)]
1385 mod tests {
1386     use expect_test::{expect, Expect};
1387     use hir::HirDisplay;
1388
1389     use crate::tests::{position, TEST_CONFIG};
1390
1391     use super::CompletionContext;
1392
1393     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
1394         let (db, pos) = position(ra_fixture);
1395         let config = TEST_CONFIG;
1396         let completion_context = CompletionContext::new(&db, pos, &config).unwrap();
1397
1398         let ty = completion_context
1399             .expected_type
1400             .map(|t| t.display_test(&db).to_string())
1401             .unwrap_or("?".to_owned());
1402
1403         let name = completion_context
1404             .expected_name
1405             .map_or_else(|| "?".to_owned(), |name| name.to_string());
1406
1407         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
1408     }
1409
1410     #[test]
1411     fn expected_type_let_without_leading_char() {
1412         cov_mark::check!(expected_type_let_without_leading_char);
1413         check_expected_type_and_name(
1414             r#"
1415 fn foo() {
1416     let x: u32 = $0;
1417 }
1418 "#,
1419             expect![[r#"ty: u32, name: x"#]],
1420         );
1421     }
1422
1423     #[test]
1424     fn expected_type_let_with_leading_char() {
1425         cov_mark::check!(expected_type_let_with_leading_char);
1426         check_expected_type_and_name(
1427             r#"
1428 fn foo() {
1429     let x: u32 = c$0;
1430 }
1431 "#,
1432             expect![[r#"ty: u32, name: x"#]],
1433         );
1434     }
1435
1436     #[test]
1437     fn expected_type_let_pat() {
1438         check_expected_type_and_name(
1439             r#"
1440 fn foo() {
1441     let x$0 = 0u32;
1442 }
1443 "#,
1444             expect![[r#"ty: u32, name: ?"#]],
1445         );
1446         check_expected_type_and_name(
1447             r#"
1448 fn foo() {
1449     let $0 = 0u32;
1450 }
1451 "#,
1452             expect![[r#"ty: u32, name: ?"#]],
1453         );
1454     }
1455
1456     #[test]
1457     fn expected_type_fn_param() {
1458         cov_mark::check!(expected_type_fn_param);
1459         check_expected_type_and_name(
1460             r#"
1461 fn foo() { bar($0); }
1462 fn bar(x: u32) {}
1463 "#,
1464             expect![[r#"ty: u32, name: x"#]],
1465         );
1466         check_expected_type_and_name(
1467             r#"
1468 fn foo() { bar(c$0); }
1469 fn bar(x: u32) {}
1470 "#,
1471             expect![[r#"ty: u32, name: x"#]],
1472         );
1473     }
1474
1475     #[test]
1476     fn expected_type_fn_param_ref() {
1477         cov_mark::check!(expected_type_fn_param_ref);
1478         check_expected_type_and_name(
1479             r#"
1480 fn foo() { bar(&$0); }
1481 fn bar(x: &u32) {}
1482 "#,
1483             expect![[r#"ty: u32, name: x"#]],
1484         );
1485         check_expected_type_and_name(
1486             r#"
1487 fn foo() { bar(&mut $0); }
1488 fn bar(x: &mut u32) {}
1489 "#,
1490             expect![[r#"ty: u32, name: x"#]],
1491         );
1492         check_expected_type_and_name(
1493             r#"
1494 fn foo() { bar(& c$0); }
1495 fn bar(x: &u32) {}
1496         "#,
1497             expect![[r#"ty: u32, name: x"#]],
1498         );
1499         check_expected_type_and_name(
1500             r#"
1501 fn foo() { bar(&mut c$0); }
1502 fn bar(x: &mut u32) {}
1503 "#,
1504             expect![[r#"ty: u32, name: x"#]],
1505         );
1506         check_expected_type_and_name(
1507             r#"
1508 fn foo() { bar(&c$0); }
1509 fn bar(x: &u32) {}
1510         "#,
1511             expect![[r#"ty: u32, name: x"#]],
1512         );
1513     }
1514
1515     #[test]
1516     fn expected_type_struct_field_without_leading_char() {
1517         cov_mark::check!(expected_type_struct_field_without_leading_char);
1518         check_expected_type_and_name(
1519             r#"
1520 struct Foo { a: u32 }
1521 fn foo() {
1522     Foo { a: $0 };
1523 }
1524 "#,
1525             expect![[r#"ty: u32, name: a"#]],
1526         )
1527     }
1528
1529     #[test]
1530     fn expected_type_struct_field_followed_by_comma() {
1531         cov_mark::check!(expected_type_struct_field_followed_by_comma);
1532         check_expected_type_and_name(
1533             r#"
1534 struct Foo { a: u32 }
1535 fn foo() {
1536     Foo { a: $0, };
1537 }
1538 "#,
1539             expect![[r#"ty: u32, name: a"#]],
1540         )
1541     }
1542
1543     #[test]
1544     fn expected_type_generic_struct_field() {
1545         check_expected_type_and_name(
1546             r#"
1547 struct Foo<T> { a: T }
1548 fn foo() -> Foo<u32> {
1549     Foo { a: $0 }
1550 }
1551 "#,
1552             expect![[r#"ty: u32, name: a"#]],
1553         )
1554     }
1555
1556     #[test]
1557     fn expected_type_struct_field_with_leading_char() {
1558         cov_mark::check!(expected_type_struct_field_with_leading_char);
1559         check_expected_type_and_name(
1560             r#"
1561 struct Foo { a: u32 }
1562 fn foo() {
1563     Foo { a: c$0 };
1564 }
1565 "#,
1566             expect![[r#"ty: u32, name: a"#]],
1567         );
1568     }
1569
1570     #[test]
1571     fn expected_type_match_arm_without_leading_char() {
1572         cov_mark::check!(expected_type_match_arm_without_leading_char);
1573         check_expected_type_and_name(
1574             r#"
1575 enum E { X }
1576 fn foo() {
1577    match E::X { $0 }
1578 }
1579 "#,
1580             expect![[r#"ty: E, name: ?"#]],
1581         );
1582     }
1583
1584     #[test]
1585     fn expected_type_match_arm_with_leading_char() {
1586         cov_mark::check!(expected_type_match_arm_with_leading_char);
1587         check_expected_type_and_name(
1588             r#"
1589 enum E { X }
1590 fn foo() {
1591    match E::X { c$0 }
1592 }
1593 "#,
1594             expect![[r#"ty: E, name: ?"#]],
1595         );
1596     }
1597
1598     #[test]
1599     fn expected_type_if_let_without_leading_char() {
1600         cov_mark::check!(expected_type_if_let_without_leading_char);
1601         check_expected_type_and_name(
1602             r#"
1603 enum Foo { Bar, Baz, Quux }
1604
1605 fn foo() {
1606     let f = Foo::Quux;
1607     if let $0 = f { }
1608 }
1609 "#,
1610             expect![[r#"ty: Foo, name: ?"#]],
1611         )
1612     }
1613
1614     #[test]
1615     fn expected_type_if_let_with_leading_char() {
1616         cov_mark::check!(expected_type_if_let_with_leading_char);
1617         check_expected_type_and_name(
1618             r#"
1619 enum Foo { Bar, Baz, Quux }
1620
1621 fn foo() {
1622     let f = Foo::Quux;
1623     if let c$0 = f { }
1624 }
1625 "#,
1626             expect![[r#"ty: Foo, name: ?"#]],
1627         )
1628     }
1629
1630     #[test]
1631     fn expected_type_fn_ret_without_leading_char() {
1632         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1633         check_expected_type_and_name(
1634             r#"
1635 fn foo() -> u32 {
1636     $0
1637 }
1638 "#,
1639             expect![[r#"ty: u32, name: ?"#]],
1640         )
1641     }
1642
1643     #[test]
1644     fn expected_type_fn_ret_with_leading_char() {
1645         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1646         check_expected_type_and_name(
1647             r#"
1648 fn foo() -> u32 {
1649     c$0
1650 }
1651 "#,
1652             expect![[r#"ty: u32, name: ?"#]],
1653         )
1654     }
1655
1656     #[test]
1657     fn expected_type_fn_ret_fn_ref_fully_typed() {
1658         check_expected_type_and_name(
1659             r#"
1660 fn foo() -> u32 {
1661     foo$0
1662 }
1663 "#,
1664             expect![[r#"ty: u32, name: ?"#]],
1665         )
1666     }
1667
1668     #[test]
1669     fn expected_type_closure_param_return() {
1670         // FIXME: make this work with `|| $0`
1671         check_expected_type_and_name(
1672             r#"
1673 //- minicore: fn
1674 fn foo() {
1675     bar(|| a$0);
1676 }
1677
1678 fn bar(f: impl FnOnce() -> u32) {}
1679 "#,
1680             expect![[r#"ty: u32, name: ?"#]],
1681         );
1682     }
1683
1684     #[test]
1685     fn expected_type_generic_function() {
1686         check_expected_type_and_name(
1687             r#"
1688 fn foo() {
1689     bar::<u32>($0);
1690 }
1691
1692 fn bar<T>(t: T) {}
1693 "#,
1694             expect![[r#"ty: u32, name: t"#]],
1695         );
1696     }
1697
1698     #[test]
1699     fn expected_type_generic_method() {
1700         check_expected_type_and_name(
1701             r#"
1702 fn foo() {
1703     S(1u32).bar($0);
1704 }
1705
1706 struct S<T>(T);
1707 impl<T> S<T> {
1708     fn bar(self, t: T) {}
1709 }
1710 "#,
1711             expect![[r#"ty: u32, name: t"#]],
1712         );
1713     }
1714
1715     #[test]
1716     fn expected_type_functional_update() {
1717         cov_mark::check!(expected_type_struct_func_update);
1718         check_expected_type_and_name(
1719             r#"
1720 struct Foo { field: u32 }
1721 fn foo() {
1722     Foo {
1723         ..$0
1724     }
1725 }
1726 "#,
1727             expect![[r#"ty: Foo, name: ?"#]],
1728         );
1729     }
1730
1731     #[test]
1732     fn expected_type_param_pat() {
1733         check_expected_type_and_name(
1734             r#"
1735 struct Foo { field: u32 }
1736 fn foo(a$0: Foo) {}
1737 "#,
1738             expect![[r#"ty: Foo, name: ?"#]],
1739         );
1740         check_expected_type_and_name(
1741             r#"
1742 struct Foo { field: u32 }
1743 fn foo($0: Foo) {}
1744 "#,
1745             // FIXME make this work, currently fails due to pattern recovery eating the `:`
1746             expect![[r#"ty: ?, name: ?"#]],
1747         );
1748     }
1749 }