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         in_functional_update: bool,
  52     },
  53     Type,
  54     Attr {
  55         kind: AttrKind,
  56         annotated_item_kind: Option<SyntaxKind>,
  57     },
  58     Derive,
  59     /// Path in item position, that is inside an (Assoc)ItemList
  60     Item {
  61         kind: ItemListKind,
  62     },
  63     Pat,
  64     Vis {
  65         has_in_token: bool,
  66     },
  67     Use,
  68 }
  69
  70 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  71 pub(super) enum ItemListKind {
  72     SourceFile,
  73     Module,
  74     Impl,
  75     Trait,
  76     ExternBlock,
  77 }
  78
  79 #[derive(Debug)]
  80 pub(crate) struct PathCompletionCtx {
  81     /// If this is a call with () already there (or {} in case of record patterns)
  82     pub(super) has_call_parens: bool,
  83     /// If this has a macro call bang !
  84     pub(super) has_macro_bang: bool,
  85     /// Whether this path stars with a `::`.
  86     pub(super) is_absolute_path: bool,
  87     /// The qualifier of the current path if it exists.
  88     pub(super) qualifier: Option<PathQualifierCtx>,
  89     #[allow(dead_code)]
  90     // FIXME: use this
  91     /// The parent of the path we are completing.
  92     pub(super) parent: Option<ast::Path>,
  93     pub(super) kind: PathKind,
  94     /// Whether the path segment has type args or not.
  95     pub(super) has_type_args: bool,
  96 }
  97
  98 #[derive(Debug)]
  99 pub(crate) struct PathQualifierCtx {
 100     pub(crate) path: ast::Path,
 101     pub(crate) resolution: Option<PathResolution>,
 102     /// Whether this path consists solely of `super` segments
 103     pub(crate) is_super_chain: bool,
 104     /// Whether the qualifier comes from a use tree parent or not
 105     pub(crate) use_tree_parent: bool,
 106     /// <_>
 107     pub(crate) is_infer_qualifier: bool,
 108 }
 109
 110 #[derive(Debug)]
 111 pub(super) struct PatternContext {
 112     pub(super) refutability: PatternRefutability,
 113     pub(super) param_ctx: Option<(ast::ParamList, ast::Param, ParamKind)>,
 114     pub(super) has_type_ascription: bool,
 115     pub(super) parent_pat: Option<ast::Pat>,
 116     pub(super) ref_token: Option<SyntaxToken>,
 117     pub(super) mut_token: Option<SyntaxToken>,
 118 }
 119
 120 #[derive(Debug)]
 121 pub(super) struct LifetimeContext {
 122     pub(super) lifetime: Option<ast::Lifetime>,
 123     pub(super) kind: LifetimeKind,
 124 }
 125
 126 #[derive(Debug)]
 127 pub(super) enum LifetimeKind {
 128     LifetimeParam { is_decl: bool, param: ast::LifetimeParam },
 129     Lifetime,
 130     LabelRef,
 131     LabelDef,
 132 }
 133
 134 #[derive(Debug)]
 135 pub(super) struct NameContext {
 136     #[allow(dead_code)]
 137     pub(super) name: Option<ast::Name>,
 138     pub(super) kind: NameKind,
 139 }
 140
 141 #[derive(Debug)]
 142 #[allow(dead_code)]
 143 pub(super) enum NameKind {
 144     Const,
 145     ConstParam,
 146     Enum,
 147     Function,
 148     IdentPat,
 149     MacroDef,
 150     MacroRules,
 151     /// Fake node
 152     Module(ast::Module),
 153     RecordField,
 154     Rename,
 155     SelfParam,
 156     Static,
 157     Struct,
 158     Trait,
 159     TypeAlias,
 160     TypeParam,
 161     Union,
 162     Variant,
 163 }
 164
 165 #[derive(Debug)]
 166 pub(super) struct NameRefContext {
 167     /// NameRef syntax in the original file
 168     pub(super) nameref: Option<ast::NameRef>,
 169     pub(super) dot_access: Option<DotAccess>,
 170     pub(super) path_ctx: Option<PathCompletionCtx>,
 171 }
 172
 173 #[derive(Debug)]
 174 pub(super) enum IdentContext {
 175     Name(NameContext),
 176     NameRef(NameRefContext),
 177     Lifetime(LifetimeContext),
 178     /// Original token, fake token
 179     String {
 180         original: ast::String,
 181         expanded: Option<ast::String>,
 182     },
 183     UnexpandedAttrTT {
 184         fake_attribute_under_caret: Option<ast::Attr>,
 185     },
 186 }
 187
 188 #[derive(Debug)]
 189 pub(super) enum DotAccess {
 190     Field {
 191         receiver: Option<ast::Expr>,
 192         /// True if the receiver is an integer and there is no ident in the original file after it yet
 193         /// like `0.$0`
 194         receiver_is_ambiguous_float_literal: bool,
 195     },
 196     Method {
 197         receiver: Option<ast::Expr>,
 198         has_parens: bool,
 199     },
 200 }
 201
 202 #[derive(Clone, Debug, PartialEq, Eq)]
 203 pub(crate) enum ParamKind {
 204     Function(ast::Fn),
 205     Closure(ast::ClosureExpr),
 206 }
 207
 208 /// `CompletionContext` is created early during completion to figure out, where
 209 /// exactly is the cursor, syntax-wise.
 210 #[derive(Debug)]
 211 pub(crate) struct CompletionContext<'a> {
 212     pub(super) sema: Semantics<'a, RootDatabase>,
 213     pub(super) scope: SemanticsScope<'a>,
 214     pub(super) db: &'a RootDatabase,
 215     pub(super) config: &'a CompletionConfig,
 216     pub(super) position: FilePosition,
 217
 218     /// The token before the cursor, in the original file.
 219     pub(super) original_token: SyntaxToken,
 220     /// The token before the cursor, in the macro-expanded file.
 221     pub(super) token: SyntaxToken,
 222     /// The crate of the current file.
 223     pub(super) krate: hir::Crate,
 224     /// The module of the `scope`.
 225     pub(super) module: hir::Module,
 226
 227     /// The expected name of what we are completing.
 228     /// This is usually the parameter name of the function argument we are completing.
 229     pub(super) expected_name: Option<NameOrNameRef>,
 230     /// The expected type of what we are completing.
 231     pub(super) expected_type: Option<Type>,
 232
 233     /// The parent function of the cursor position if it exists.
 234     pub(super) function_def: Option<ast::Fn>,
 235     /// The parent impl of the cursor position if it exists.
 236     pub(super) impl_def: Option<ast::Impl>,
 237     /// Are we completing inside a let statement with a missing semicolon?
 238     pub(super) incomplete_let: bool,
 239
 240     pub(super) completion_location: Option<ImmediateLocation>,
 241     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
 242     pub(super) previous_token: Option<SyntaxToken>,
 243
 244     pub(super) ident_ctx: IdentContext,
 245
 246     pub(super) pattern_ctx: Option<PatternContext>,
 247
 248     pub(super) existing_derives: FxHashSet<hir::Macro>,
 249
 250     pub(super) locals: FxHashMap<Name, Local>,
 251 }
 252
 253 impl<'a> CompletionContext<'a> {
 254     /// The range of the identifier that is being completed.
 255     pub(crate) fn source_range(&self) -> TextRange {
 256         // check kind of macro-expanded token, but use range of original token
 257         let kind = self.token.kind();
 258         match kind {
 259             CHAR => {
 260                 // assume we are completing a lifetime but the user has only typed the '
 261                 cov_mark::hit!(completes_if_lifetime_without_idents);
 262                 TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 263             }
 264             IDENT | LIFETIME_IDENT | UNDERSCORE => self.original_token.text_range(),
 265             _ if kind.is_keyword() => self.original_token.text_range(),
 266             _ => TextRange::empty(self.position.offset),
 267         }
 268     }
 269
 270     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 271         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 272     }
 273
 274     pub(crate) fn famous_defs(&self) -> FamousDefs {
 275         FamousDefs(&self.sema, self.krate)
 276     }
 277
 278     pub(super) fn nameref_ctx(&self) -> Option<&NameRefContext> {
 279         match &self.ident_ctx {
 280             IdentContext::NameRef(it) => Some(it),
 281             _ => None,
 282         }
 283     }
 284
 285     pub(super) fn name_ctx(&self) -> Option<&NameContext> {
 286         match &self.ident_ctx {
 287             IdentContext::Name(it) => Some(it),
 288             _ => None,
 289         }
 290     }
 291
 292     pub(super) fn lifetime_ctx(&self) -> Option<&LifetimeContext> {
 293         match &self.ident_ctx {
 294             IdentContext::Lifetime(it) => Some(it),
 295             _ => None,
 296         }
 297     }
 298
 299     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 300         match self.nameref_ctx() {
 301             Some(NameRefContext {
 302                 dot_access:
 303                     Some(DotAccess::Method { receiver, .. } | DotAccess::Field { receiver, .. }),
 304                 ..
 305             }) => receiver.as_ref(),
 306             _ => None,
 307         }
 308     }
 309
 310     pub(crate) fn has_dot_receiver(&self) -> bool {
 311         self.dot_receiver().is_some()
 312     }
 313
 314     pub(crate) fn expects_assoc_item(&self) -> bool {
 315         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 316     }
 317
 318     pub(crate) fn expects_variant(&self) -> bool {
 319         matches!(self.name_ctx(), Some(NameContext { kind: NameKind::Variant, .. }))
 320     }
 321
 322     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 323         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 324     }
 325
 326     pub(crate) fn expects_item(&self) -> bool {
 327         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 328     }
 329
 330     // FIXME: This shouldn't exist
 331     pub(crate) fn expects_generic_arg(&self) -> bool {
 332         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 333     }
 334
 335     pub(crate) fn has_block_expr_parent(&self) -> bool {
 336         matches!(self.completion_location, Some(ImmediateLocation::StmtList))
 337     }
 338
 339     pub(crate) fn expects_ident_ref_expr(&self) -> bool {
 340         matches!(self.completion_location, Some(ImmediateLocation::RefExpr))
 341     }
 342
 343     pub(crate) fn expect_field(&self) -> bool {
 344         matches!(self.completion_location, Some(ImmediateLocation::TupleField))
 345             || matches!(self.name_ctx(), Some(NameContext { kind: NameKind::RecordField, .. }))
 346     }
 347
 348     /// Whether the cursor is right after a trait or impl header.
 349     /// trait Foo ident$0
 350     // FIXME: This probably shouldn't exist
 351     pub(crate) fn has_unfinished_impl_or_trait_prev_sibling(&self) -> bool {
 352         matches!(
 353             self.prev_sibling,
 354             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 355         )
 356     }
 357
 358     // FIXME: This probably shouldn't exist
 359     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 360         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 361     }
 362
 363     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 364         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 365     }
 366
 367     pub(crate) fn after_if(&self) -> bool {
 368         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 369     }
 370
 371     // FIXME: This shouldn't exist
 372     pub(crate) fn is_path_disallowed(&self) -> bool {
 373         self.previous_token_is(T![unsafe])
 374             || matches!(
 375                 self.prev_sibling,
 376                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 377             )
 378             || matches!(
 379                 self.completion_location,
 380                 Some(ImmediateLocation::RecordPat(_) | ImmediateLocation::RecordExpr(_))
 381             )
 382             || matches!(
 383                 self.name_ctx(),
 384                 Some(NameContext { kind: NameKind::Module(_) | NameKind::Rename, .. })
 385             )
 386     }
 387
 388     pub(crate) fn path_context(&self) -> Option<&PathCompletionCtx> {
 389         self.nameref_ctx().and_then(|ctx| ctx.path_ctx.as_ref())
 390     }
 391
 392     pub(crate) fn expects_expression(&self) -> bool {
 393         matches!(self.path_context(), Some(PathCompletionCtx { kind: PathKind::Expr { .. }, .. }))
 394     }
 395
 396     pub(crate) fn is_non_trivial_path(&self) -> bool {
 397         matches!(
 398             self.path_context(),
 399             Some(
 400                 PathCompletionCtx { is_absolute_path: true, .. }
 401                     | PathCompletionCtx { qualifier: Some(_), .. }
 402             )
 403         )
 404     }
 405
 406     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 407         self.path_context().and_then(|it| it.qualifier.as_ref().map(|it| &it.path))
 408     }
 409
 410     pub(crate) fn path_kind(&self) -> Option<PathKind> {
 411         self.path_context().map(|it| it.kind)
 412     }
 413
 414     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 415     pub(crate) fn is_visible<I>(&self, item: &I) -> Visible
 416     where
 417         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 418     {
 419         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 420     }
 421
 422     pub(crate) fn is_scope_def_hidden(&self, scope_def: ScopeDef) -> bool {
 423         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 424             return self.is_doc_hidden(&attrs, krate);
 425         }
 426
 427         false
 428     }
 429
 430     /// Check if an item is `#[doc(hidden)]`.
 431     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
 432         let attrs = item.attrs(self.db);
 433         let krate = item.krate(self.db);
 434         match (attrs, krate) {
 435             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
 436             _ => false,
 437         }
 438     }
 439     /// Whether the given trait is an operator trait or not.
 440     pub(crate) fn is_ops_trait(&self, trait_: hir::Trait) -> bool {
 441         match trait_.attrs(self.db).lang() {
 442             Some(lang) => OP_TRAIT_LANG_NAMES.contains(&lang.as_str()),
 443             None => false,
 444         }
 445     }
 446
 447     /// Returns the traits in scope, with the [`Drop`] trait removed.
 448     pub(crate) fn traits_in_scope(&self) -> hir::VisibleTraits {
 449         let mut traits_in_scope = self.scope.visible_traits();
 450         if let Some(drop) = self.famous_defs().core_ops_Drop() {
 451             traits_in_scope.0.remove(&drop.into());
 452         }
 453         traits_in_scope
 454     }
 455
 456     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 457     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 458         let _p = profile::span("CompletionContext::process_all_names");
 459         self.scope.process_all_names(&mut |name, def| {
 460             if self.is_scope_def_hidden(def) {
 461                 return;
 462             }
 463
 464             f(name, def);
 465         });
 466     }
 467
 468     pub(crate) fn process_all_names_raw(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 469         let _p = profile::span("CompletionContext::process_all_names_raw");
 470         self.scope.process_all_names(&mut |name, def| f(name, def));
 471     }
 472
 473     fn is_visible_impl(
 474         &self,
 475         vis: &hir::Visibility,
 476         attrs: &hir::Attrs,
 477         defining_crate: hir::Crate,
 478     ) -> Visible {
 479         if !vis.is_visible_from(self.db, self.module.into()) {
 480             if !self.config.enable_private_editable {
 481                 return Visible::No;
 482             }
 483             // If the definition location is editable, also show private items
 484             let root_file = defining_crate.root_file(self.db);
 485             let source_root_id = self.db.file_source_root(root_file);
 486             let is_editable = !self.db.source_root(source_root_id).is_library;
 487             return if is_editable { Visible::Editable } else { Visible::No };
 488         }
 489
 490         if self.is_doc_hidden(attrs, defining_crate) {
 491             Visible::No
 492         } else {
 493             Visible::Yes
 494         }
 495     }
 496
 497     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 498         // `doc(hidden)` items are only completed within the defining crate.
 499         self.krate != defining_crate && attrs.has_doc_hidden()
 500     }
 501 }
 502
 503 // CompletionContext construction
 504 impl<'a> CompletionContext<'a> {
 505     pub(super) fn new(
 506         db: &'a RootDatabase,
 507         position @ FilePosition { file_id, offset }: FilePosition,
 508         config: &'a CompletionConfig,
 509     ) -> Option<CompletionContext<'a>> {
 510         let _p = profile::span("CompletionContext::new");
 511         let sema = Semantics::new(db);
 512
 513         let original_file = sema.parse(file_id);
 514
 515         // Insert a fake ident to get a valid parse tree. We will use this file
 516         // to determine context, though the original_file will be used for
 517         // actual completion.
 518         let file_with_fake_ident = {
 519             let parse = db.parse(file_id);
 520             let edit = Indel::insert(offset, COMPLETION_MARKER.to_string());
 521             parse.reparse(&edit).tree()
 522         };
 523         let fake_ident_token =
 524             file_with_fake_ident.syntax().token_at_offset(offset).right_biased()?;
 525
 526         let original_token = original_file.syntax().token_at_offset(offset).left_biased()?;
 527         let token = sema.descend_into_macros_single(original_token.clone());
 528         let scope = sema.scope_at_offset(&token.parent()?, offset)?;
 529         let krate = scope.krate();
 530         let module = scope.module();
 531
 532         let mut locals = FxHashMap::default();
 533         scope.process_all_names(&mut |name, scope| {
 534             if let ScopeDef::Local(local) = scope {
 535                 locals.insert(name, local);
 536             }
 537         });
 538
 539         let mut ctx = CompletionContext {
 540             sema,
 541             scope,
 542             db,
 543             config,
 544             position,
 545             original_token,
 546             token,
 547             krate,
 548             module,
 549             expected_name: None,
 550             expected_type: None,
 551             function_def: None,
 552             impl_def: None,
 553             incomplete_let: false,
 554             completion_location: None,
 555             prev_sibling: None,
 556             previous_token: None,
 557             // dummy value, will be overwritten
 558             ident_ctx: IdentContext::UnexpandedAttrTT { fake_attribute_under_caret: None },
 559             pattern_ctx: None,
 560             existing_derives: Default::default(),
 561             locals,
 562         };
 563         ctx.expand_and_fill(
 564             original_file.syntax().clone(),
 565             file_with_fake_ident.syntax().clone(),
 566             offset,
 567             fake_ident_token,
 568         )?;
 569         Some(ctx)
 570     }
 571
 572     /// Expand attributes and macro calls at the current cursor position for both the original file
 573     /// and fake file repeatedly. As soon as one of the two expansions fail we stop so the original
 574     /// and speculative states stay in sync.
 575     fn expand_and_fill(
 576         &mut self,
 577         mut original_file: SyntaxNode,
 578         mut speculative_file: SyntaxNode,
 579         mut offset: TextSize,
 580         mut fake_ident_token: SyntaxToken,
 581     ) -> Option<()> {
 582         let _p = profile::span("CompletionContext::expand_and_fill");
 583         let mut derive_ctx = None;
 584
 585         'expansion: loop {
 586             let parent_item =
 587                 |item: &ast::Item| item.syntax().ancestors().skip(1).find_map(ast::Item::cast);
 588             let ancestor_items = iter::successors(
 589                 Option::zip(
 590                     find_node_at_offset::<ast::Item>(&original_file, offset),
 591                     find_node_at_offset::<ast::Item>(&speculative_file, offset),
 592                 ),
 593                 |(a, b)| parent_item(a).zip(parent_item(b)),
 594             );
 595
 596             // first try to expand attributes as these are always the outermost macro calls
 597             'ancestors: for (actual_item, item_with_fake_ident) in ancestor_items {
 598                 match (
 599                     self.sema.expand_attr_macro(&actual_item),
 600                     self.sema.speculative_expand_attr_macro(
 601                         &actual_item,
 602                         &item_with_fake_ident,
 603                         fake_ident_token.clone(),
 604                     ),
 605                 ) {
 606                     // maybe parent items have attributes, so continue walking the ancestors
 607                     (None, None) => continue 'ancestors,
 608                     // successful expansions
 609                     (Some(actual_expansion), Some((fake_expansion, fake_mapped_token))) => {
 610                         let new_offset = fake_mapped_token.text_range().start();
 611                         if new_offset > actual_expansion.text_range().end() {
 612                             // offset outside of bounds from the original expansion,
 613                             // stop here to prevent problems from happening
 614                             break 'expansion;
 615                         }
 616                         original_file = actual_expansion;
 617                         speculative_file = fake_expansion;
 618                         fake_ident_token = fake_mapped_token;
 619                         offset = new_offset;
 620                         continue 'expansion;
 621                     }
 622                     // exactly one expansion failed, inconsistent state so stop expanding completely
 623                     _ => break 'expansion,
 624                 }
 625             }
 626
 627             // No attributes have been expanded, so look for macro_call! token trees or derive token trees
 628             let orig_tt = match find_node_at_offset::<ast::TokenTree>(&original_file, offset) {
 629                 Some(it) => it,
 630                 None => break 'expansion,
 631             };
 632             let spec_tt = match find_node_at_offset::<ast::TokenTree>(&speculative_file, offset) {
 633                 Some(it) => it,
 634                 None => break 'expansion,
 635             };
 636
 637             // Expand pseudo-derive expansion
 638             if let (Some(orig_attr), Some(spec_attr)) = (
 639                 orig_tt.syntax().parent().and_then(ast::Meta::cast).and_then(|it| it.parent_attr()),
 640                 spec_tt.syntax().parent().and_then(ast::Meta::cast).and_then(|it| it.parent_attr()),
 641             ) {
 642                 if let (Some(actual_expansion), Some((fake_expansion, fake_mapped_token))) = (
 643                     self.sema.expand_derive_as_pseudo_attr_macro(&orig_attr),
 644                     self.sema.speculative_expand_derive_as_pseudo_attr_macro(
 645                         &orig_attr,
 646                         &spec_attr,
 647                         fake_ident_token.clone(),
 648                     ),
 649                 ) {
 650                     derive_ctx = Some((
 651                         actual_expansion,
 652                         fake_expansion,
 653                         fake_mapped_token.text_range().start(),
 654                         orig_attr,
 655                     ));
 656                 }
 657                 // at this point we won't have any more successful expansions, so stop
 658                 break 'expansion;
 659             }
 660
 661             // Expand fn-like macro calls
 662             if let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 663                 orig_tt.syntax().ancestors().find_map(ast::MacroCall::cast),
 664                 spec_tt.syntax().ancestors().find_map(ast::MacroCall::cast),
 665             ) {
 666                 let mac_call_path0 = actual_macro_call.path().as_ref().map(|s| s.syntax().text());
 667                 let mac_call_path1 =
 668                     macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text());
 669
 670                 // inconsistent state, stop expanding
 671                 if mac_call_path0 != mac_call_path1 {
 672                     break 'expansion;
 673                 }
 674                 let speculative_args = match macro_call_with_fake_ident.token_tree() {
 675                     Some(tt) => tt,
 676                     None => break 'expansion,
 677                 };
 678
 679                 match (
 680                     self.sema.expand(&actual_macro_call),
 681                     self.sema.speculative_expand(
 682                         &actual_macro_call,
 683                         &speculative_args,
 684                         fake_ident_token.clone(),
 685                     ),
 686                 ) {
 687                     // successful expansions
 688                     (Some(actual_expansion), Some((fake_expansion, fake_mapped_token))) => {
 689                         let new_offset = fake_mapped_token.text_range().start();
 690                         if new_offset > actual_expansion.text_range().end() {
 691                             // offset outside of bounds from the original expansion,
 692                             // stop here to prevent problems from happening
 693                             break 'expansion;
 694                         }
 695                         original_file = actual_expansion;
 696                         speculative_file = fake_expansion;
 697                         fake_ident_token = fake_mapped_token;
 698                         offset = new_offset;
 699                         continue 'expansion;
 700                     }
 701                     // at least on expansion failed, we won't have anything to expand from this point
 702                     // onwards so break out
 703                     _ => break 'expansion,
 704                 }
 705             }
 706
 707             // none of our states have changed so stop the loop
 708             break 'expansion;
 709         }
 710
 711         self.fill(&original_file, speculative_file, offset, derive_ctx)
 712     }
 713
 714     /// Calculate the expected type and name of the cursor position.
 715     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 716         let mut node = match self.token.parent() {
 717             Some(it) => it,
 718             None => return (None, None),
 719         };
 720         loop {
 721             break match_ast! {
 722                 match node {
 723                     ast::LetStmt(it) => {
 724                         cov_mark::hit!(expected_type_let_with_leading_char);
 725                         cov_mark::hit!(expected_type_let_without_leading_char);
 726                         let ty = it.pat()
 727                             .and_then(|pat| self.sema.type_of_pat(&pat))
 728                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)))
 729                             .map(TypeInfo::original);
 730                         let name = match it.pat() {
 731                             Some(ast::Pat::IdentPat(ident)) => ident.name().map(NameOrNameRef::Name),
 732                             Some(_) | None => None,
 733                         };
 734
 735                         (ty, name)
 736                     },
 737                     ast::LetExpr(it) => {
 738                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 739                         let ty = it.pat()
 740                             .and_then(|pat| self.sema.type_of_pat(&pat))
 741                             .or_else(|| it.expr().and_then(|it| self.sema.type_of_expr(&it)))
 742                             .map(TypeInfo::original);
 743                         (ty, None)
 744                     },
 745                     ast::ArgList(_) => {
 746                         cov_mark::hit!(expected_type_fn_param);
 747                         ActiveParameter::at_token(
 748                             &self.sema,
 749                             self.token.clone(),
 750                         ).map(|ap| {
 751                             let name = ap.ident().map(NameOrNameRef::Name);
 752                             let ty = if has_ref(&self.token) {
 753                                 cov_mark::hit!(expected_type_fn_param_ref);
 754                                 ap.ty.remove_ref()
 755                             } else {
 756                                 Some(ap.ty)
 757                             };
 758                             (ty, name)
 759                         })
 760                         .unwrap_or((None, None))
 761                     },
 762                     ast::RecordExprFieldList(it) => {
 763                         // wouldn't try {} be nice...
 764                         (|| {
 765                             if self.token.kind() == T![..]
 766                                 || self.token.prev_token().map(|t| t.kind()) == Some(T![..])
 767                             {
 768                                 cov_mark::hit!(expected_type_struct_func_update);
 769                                 let record_expr = it.syntax().parent().and_then(ast::RecordExpr::cast)?;
 770                                 let ty = self.sema.type_of_expr(&record_expr.into())?;
 771                                 Some((
 772                                     Some(ty.original),
 773                                     None
 774                                 ))
 775                             } else {
 776                                 cov_mark::hit!(expected_type_struct_field_without_leading_char);
 777                                 let expr_field = self.token.prev_sibling_or_token()?
 778                                     .into_node()
 779                                     .and_then(ast::RecordExprField::cast)?;
 780                                 let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 781                                 Some((
 782                                     Some(ty),
 783                                     expr_field.field_name().map(NameOrNameRef::NameRef),
 784                                 ))
 785                             }
 786                         })().unwrap_or((None, None))
 787                     },
 788                     ast::RecordExprField(it) => {
 789                         if let Some(expr) = it.expr() {
 790                             cov_mark::hit!(expected_type_struct_field_with_leading_char);
 791                             (
 792                                 self.sema.type_of_expr(&expr).map(TypeInfo::original),
 793                                 it.field_name().map(NameOrNameRef::NameRef),
 794                             )
 795                         } else {
 796                             cov_mark::hit!(expected_type_struct_field_followed_by_comma);
 797                             let ty = self.sema.resolve_record_field(&it)
 798                                 .map(|(_, _, ty)| ty);
 799                             (
 800                                 ty,
 801                                 it.field_name().map(NameOrNameRef::NameRef),
 802                             )
 803                         }
 804                     },
 805                     // match foo { $0 }
 806                     // match foo { ..., pat => $0 }
 807                     ast::MatchExpr(it) => {
 808                         let ty = if self.previous_token_is(T![=>]) {
 809                             // match foo { ..., pat => $0 }
 810                             cov_mark::hit!(expected_type_match_arm_body_without_leading_char);
 811                             cov_mark::hit!(expected_type_match_arm_body_with_leading_char);
 812                             self.sema.type_of_expr(&it.into())
 813                         } else {
 814                             // match foo { $0 }
 815                             cov_mark::hit!(expected_type_match_arm_without_leading_char);
 816                             it.expr().and_then(|e| self.sema.type_of_expr(&e))
 817                         }.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.text().ends_with('.'))
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         let is_in_func_update = |it: &SyntaxNode| {
1115             it.parent().map_or(false, |it| ast::RecordExprFieldList::can_cast(it.kind()))
1116         };
1117
1118         let kind = path.syntax().ancestors().find_map(|it| {
1119             // using Option<Option<PathKind>> as extra controlflow
1120             let kind = match_ast! {
1121                 match it {
1122                     ast::PathType(_) => Some(PathKind::Type),
1123                     ast::PathExpr(it) => {
1124                         path_ctx.has_call_parens = it.syntax().parent().map_or(false, |it| ast::CallExpr::can_cast(it.kind()));
1125                         let in_block_expr = is_in_block(it.syntax());
1126                         let in_loop_body = is_in_loop_body(it.syntax());
1127                         let in_functional_update = is_in_func_update(it.syntax());
1128                         Some(PathKind::Expr { in_block_expr, in_loop_body, in_functional_update })
1129                     },
1130                     ast::TupleStructPat(it) => {
1131                         path_ctx.has_call_parens = true;
1132                         pat_ctx = Some(pattern_context_for(original_file, it.into()));
1133                         Some(PathKind::Pat)
1134                     },
1135                     ast::RecordPat(it) => {
1136                         path_ctx.has_call_parens = true;
1137                         pat_ctx = Some(pattern_context_for(original_file, it.into()));
1138                         Some(PathKind::Pat)
1139                     },
1140                     ast::PathPat(it) => {
1141                         pat_ctx = Some(pattern_context_for(original_file, it.into()));
1142                         Some(PathKind::Pat)
1143                     },
1144                     ast::MacroCall(it) => {
1145                         path_ctx.has_macro_bang = it.excl_token().is_some();
1146                         let parent = it.syntax().parent();
1147                         match parent.as_ref().map(|it| it.kind()) {
1148                             Some(SyntaxKind::MACRO_PAT) => Some(PathKind::Pat),
1149                             Some(SyntaxKind::MACRO_TYPE) => Some(PathKind::Type),
1150                             Some(SyntaxKind::ITEM_LIST) => Some(PathKind::Item { kind: ItemListKind::Module }),
1151                             Some(SyntaxKind::ASSOC_ITEM_LIST) => Some(PathKind::Item { kind: match parent.and_then(|it| it.parent()).map(|it| it.kind()) {
1152                                 Some(SyntaxKind::TRAIT) => ItemListKind::Trait,
1153                                 Some(SyntaxKind::IMPL) => ItemListKind::Impl,
1154                                 _ => return Some(None),
1155                             } }),
1156                             Some(SyntaxKind::EXTERN_ITEM_LIST) => Some(PathKind::Item { kind: ItemListKind::ExternBlock }),
1157                             Some(SyntaxKind::SOURCE_FILE) => Some(PathKind::Item { kind: ItemListKind::SourceFile }),
1158                             _ => {
1159                                return Some(parent.and_then(ast::MacroExpr::cast).map(|it| {
1160                                     let in_loop_body = is_in_loop_body(it.syntax());
1161                                     let in_block_expr = is_in_block(it.syntax());
1162                                     let in_functional_update = is_in_func_update(it.syntax());
1163                                     PathKind::Expr { in_block_expr, in_loop_body, in_functional_update }
1164                                 }));
1165                             },
1166                         }
1167                     },
1168                     ast::Meta(meta) => (|| {
1169                         let attr = meta.parent_attr()?;
1170                         let kind = attr.kind();
1171                         let attached = attr.syntax().parent()?;
1172                         let is_trailing_outer_attr = kind != AttrKind::Inner
1173                             && non_trivia_sibling(attr.syntax().clone().into(), syntax::Direction::Next).is_none();
1174                         let annotated_item_kind = if is_trailing_outer_attr {
1175                             None
1176                         } else {
1177                             Some(attached.kind())
1178                         };
1179                         Some(PathKind::Attr {
1180                             kind,
1181                             annotated_item_kind,
1182                         })
1183                     })(),
1184                     ast::Visibility(it) => Some(PathKind::Vis { has_in_token: it.in_token().is_some() }),
1185                     ast::UseTree(_) => Some(PathKind::Use),
1186                     ast::ItemList(_) => Some(PathKind::Item { kind: ItemListKind::Module }),
1187                     ast::AssocItemList(it) => Some(PathKind::Item { kind: {
1188                             match it.syntax().parent()?.kind() {
1189                                 SyntaxKind::TRAIT => ItemListKind::Trait,
1190                                 SyntaxKind::IMPL => ItemListKind::Impl,
1191                                 _ => return None,
1192                             }
1193                         }}),
1194                     ast::ExternItemList(_) => Some(PathKind::Item { kind: ItemListKind::ExternBlock }),
1195                     ast::SourceFile(_) => Some(PathKind::Item { kind: ItemListKind::SourceFile }),
1196                     _ => return None,
1197                 }
1198             };
1199             Some(kind)
1200         }).flatten();
1201         match kind {
1202             Some(kind) => path_ctx.kind = kind,
1203             None => return (nameref_ctx, pat_ctx),
1204         }
1205         path_ctx.has_type_args = segment.generic_arg_list().is_some();
1206
1207         if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
1208             if !use_tree_parent {
1209                 path_ctx.is_absolute_path =
1210                     path.top_path().segment().map_or(false, |it| it.coloncolon_token().is_some());
1211             }
1212
1213             let path = path
1214                 .segment()
1215                 .and_then(|it| find_node_in_file(original_file, &it))
1216                 .map(|it| it.parent_path());
1217             path_ctx.qualifier = path.map(|path| {
1218                 let res = sema.resolve_path(&path);
1219                 let is_super_chain = iter::successors(Some(path.clone()), |p| p.qualifier())
1220                     .all(|p| p.segment().and_then(|s| s.super_token()).is_some());
1221
1222                 // `<_>::$0`
1223                 let is_infer_qualifier = path.qualifier().is_none()
1224                     && matches!(
1225                         path.segment().and_then(|it| it.kind()),
1226                         Some(ast::PathSegmentKind::Type {
1227                             type_ref: Some(ast::Type::InferType(_)),
1228                             trait_ref: None,
1229                         })
1230                     );
1231
1232                 PathQualifierCtx {
1233                     path,
1234                     resolution: res,
1235                     is_super_chain,
1236                     use_tree_parent,
1237                     is_infer_qualifier,
1238                 }
1239             });
1240         } else if let Some(segment) = path.segment() {
1241             if segment.coloncolon_token().is_some() {
1242                 path_ctx.is_absolute_path = true;
1243             }
1244         }
1245         nameref_ctx.path_ctx = Some(path_ctx);
1246         (nameref_ctx, pat_ctx)
1247     }
1248 }
1249
1250 fn pattern_context_for(original_file: &SyntaxNode, pat: ast::Pat) -> PatternContext {
1251     let mut is_param = None;
1252     let (refutability, has_type_ascription) =
1253     pat
1254         .syntax()
1255         .ancestors()
1256         .skip_while(|it| ast::Pat::can_cast(it.kind()))
1257         .next()
1258         .map_or((PatternRefutability::Irrefutable, false), |node| {
1259             let refutability = match_ast! {
1260                 match node {
1261                     ast::LetStmt(let_) => return (PatternRefutability::Irrefutable, let_.ty().is_some()),
1262                     ast::Param(param) => {
1263                         let has_type_ascription = param.ty().is_some();
1264                         is_param = (|| {
1265                             let fake_param_list = param.syntax().parent().and_then(ast::ParamList::cast)?;
1266                             let param_list = find_node_in_file_compensated(original_file, &fake_param_list)?;
1267                             let param_list_owner = param_list.syntax().parent()?;
1268                             let kind = match_ast! {
1269                                 match param_list_owner {
1270                                     ast::ClosureExpr(closure) => ParamKind::Closure(closure),
1271                                     ast::Fn(fn_) => ParamKind::Function(fn_),
1272                                     _ => return None,
1273                                 }
1274                             };
1275                             Some((param_list, param, kind))
1276                         })();
1277                         return (PatternRefutability::Irrefutable, has_type_ascription)
1278                     },
1279                     ast::MatchArm(_) => PatternRefutability::Refutable,
1280                     ast::LetExpr(_) => PatternRefutability::Refutable,
1281                     ast::ForExpr(_) => PatternRefutability::Irrefutable,
1282                     _ => PatternRefutability::Irrefutable,
1283                 }
1284             };
1285             (refutability, false)
1286         });
1287     let (ref_token, mut_token) = match &pat {
1288         ast::Pat::IdentPat(it) => (it.ref_token(), it.mut_token()),
1289         _ => (None, None),
1290     };
1291     PatternContext {
1292         refutability,
1293         param_ctx: is_param,
1294         has_type_ascription,
1295         parent_pat: pat.syntax().parent().and_then(ast::Pat::cast),
1296         mut_token,
1297         ref_token,
1298     }
1299 }
1300
1301 fn find_in_original_file<N: AstNode>(x: Option<N>, original_file: &SyntaxNode) -> Option<N> {
1302     fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
1303         let range = syntax.text_range().intersect(range)?;
1304         syntax.covering_element(range).ancestors().find_map(N::cast)
1305     }
1306     x.map(|e| e.syntax().text_range()).and_then(|r| find_node_with_range(original_file, r))
1307 }
1308
1309 /// Attempts to find `node` inside `syntax` via `node`'s text range.
1310 fn find_node_in_file<N: AstNode>(syntax: &SyntaxNode, node: &N) -> Option<N> {
1311     let syntax_range = syntax.text_range();
1312     let range = node.syntax().text_range();
1313     let intersection = range.intersect(syntax_range)?;
1314     syntax.covering_element(intersection).ancestors().find_map(N::cast)
1315 }
1316
1317 /// Attempts to find `node` inside `syntax` via `node`'s text range while compensating
1318 /// for the offset introduced by the fake ident.
1319 /// This is wrong if `node` comes before the insertion point! Use `find_node_in_file` instead.
1320 fn find_node_in_file_compensated<N: AstNode>(syntax: &SyntaxNode, node: &N) -> Option<N> {
1321     let syntax_range = syntax.text_range();
1322     let range = node.syntax().text_range();
1323     let end = range.end().checked_sub(TextSize::try_from(COMPLETION_MARKER.len()).ok()?)?;
1324     if end < range.start() {
1325         return None;
1326     }
1327     let range = TextRange::new(range.start(), end);
1328     // our inserted ident could cause `range` to be go outside of the original syntax, so cap it
1329     let intersection = range.intersect(syntax_range)?;
1330     syntax.covering_element(intersection).ancestors().find_map(N::cast)
1331 }
1332
1333 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
1334     if let Some(qual) = path.qualifier() {
1335         return Some((qual, false));
1336     }
1337     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
1338     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
1339     Some((use_tree.path()?, true))
1340 }
1341
1342 fn has_ref(token: &SyntaxToken) -> bool {
1343     let mut token = token.clone();
1344     for skip in [IDENT, WHITESPACE, T![mut]] {
1345         if token.kind() == skip {
1346             token = match token.prev_token() {
1347                 Some(it) => it,
1348                 None => return false,
1349             }
1350         }
1351     }
1352     token.kind() == T![&]
1353 }
1354
1355 const OP_TRAIT_LANG_NAMES: &[&str] = &[
1356     "add_assign",
1357     "add",
1358     "bitand_assign",
1359     "bitand",
1360     "bitor_assign",
1361     "bitor",
1362     "bitxor_assign",
1363     "bitxor",
1364     "deref_mut",
1365     "deref",
1366     "div_assign",
1367     "div",
1368     "eq",
1369     "fn_mut",
1370     "fn_once",
1371     "fn",
1372     "index_mut",
1373     "index",
1374     "mul_assign",
1375     "mul",
1376     "neg",
1377     "not",
1378     "partial_ord",
1379     "rem_assign",
1380     "rem",
1381     "shl_assign",
1382     "shl",
1383     "shr_assign",
1384     "shr",
1385     "sub",
1386 ];
1387
1388 #[cfg(test)]
1389 mod tests {
1390     use expect_test::{expect, Expect};
1391     use hir::HirDisplay;
1392
1393     use crate::tests::{position, TEST_CONFIG};
1394
1395     use super::CompletionContext;
1396
1397     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
1398         let (db, pos) = position(ra_fixture);
1399         let config = TEST_CONFIG;
1400         let completion_context = CompletionContext::new(&db, pos, &config).unwrap();
1401
1402         let ty = completion_context
1403             .expected_type
1404             .map(|t| t.display_test(&db).to_string())
1405             .unwrap_or("?".to_owned());
1406
1407         let name = completion_context
1408             .expected_name
1409             .map_or_else(|| "?".to_owned(), |name| name.to_string());
1410
1411         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
1412     }
1413
1414     #[test]
1415     fn expected_type_let_without_leading_char() {
1416         cov_mark::check!(expected_type_let_without_leading_char);
1417         check_expected_type_and_name(
1418             r#"
1419 fn foo() {
1420     let x: u32 = $0;
1421 }
1422 "#,
1423             expect![[r#"ty: u32, name: x"#]],
1424         );
1425     }
1426
1427     #[test]
1428     fn expected_type_let_with_leading_char() {
1429         cov_mark::check!(expected_type_let_with_leading_char);
1430         check_expected_type_and_name(
1431             r#"
1432 fn foo() {
1433     let x: u32 = c$0;
1434 }
1435 "#,
1436             expect![[r#"ty: u32, name: x"#]],
1437         );
1438     }
1439
1440     #[test]
1441     fn expected_type_let_pat() {
1442         check_expected_type_and_name(
1443             r#"
1444 fn foo() {
1445     let x$0 = 0u32;
1446 }
1447 "#,
1448             expect![[r#"ty: u32, name: ?"#]],
1449         );
1450         check_expected_type_and_name(
1451             r#"
1452 fn foo() {
1453     let $0 = 0u32;
1454 }
1455 "#,
1456             expect![[r#"ty: u32, name: ?"#]],
1457         );
1458     }
1459
1460     #[test]
1461     fn expected_type_fn_param() {
1462         cov_mark::check!(expected_type_fn_param);
1463         check_expected_type_and_name(
1464             r#"
1465 fn foo() { bar($0); }
1466 fn bar(x: u32) {}
1467 "#,
1468             expect![[r#"ty: u32, name: x"#]],
1469         );
1470         check_expected_type_and_name(
1471             r#"
1472 fn foo() { bar(c$0); }
1473 fn bar(x: u32) {}
1474 "#,
1475             expect![[r#"ty: u32, name: x"#]],
1476         );
1477     }
1478
1479     #[test]
1480     fn expected_type_fn_param_ref() {
1481         cov_mark::check!(expected_type_fn_param_ref);
1482         check_expected_type_and_name(
1483             r#"
1484 fn foo() { bar(&$0); }
1485 fn bar(x: &u32) {}
1486 "#,
1487             expect![[r#"ty: u32, name: x"#]],
1488         );
1489         check_expected_type_and_name(
1490             r#"
1491 fn foo() { bar(&mut $0); }
1492 fn bar(x: &mut u32) {}
1493 "#,
1494             expect![[r#"ty: u32, name: x"#]],
1495         );
1496         check_expected_type_and_name(
1497             r#"
1498 fn foo() { bar(& c$0); }
1499 fn bar(x: &u32) {}
1500         "#,
1501             expect![[r#"ty: u32, name: x"#]],
1502         );
1503         check_expected_type_and_name(
1504             r#"
1505 fn foo() { bar(&mut c$0); }
1506 fn bar(x: &mut u32) {}
1507 "#,
1508             expect![[r#"ty: u32, name: x"#]],
1509         );
1510         check_expected_type_and_name(
1511             r#"
1512 fn foo() { bar(&c$0); }
1513 fn bar(x: &u32) {}
1514         "#,
1515             expect![[r#"ty: u32, name: x"#]],
1516         );
1517     }
1518
1519     #[test]
1520     fn expected_type_struct_field_without_leading_char() {
1521         cov_mark::check!(expected_type_struct_field_without_leading_char);
1522         check_expected_type_and_name(
1523             r#"
1524 struct Foo { a: u32 }
1525 fn foo() {
1526     Foo { a: $0 };
1527 }
1528 "#,
1529             expect![[r#"ty: u32, name: a"#]],
1530         )
1531     }
1532
1533     #[test]
1534     fn expected_type_struct_field_followed_by_comma() {
1535         cov_mark::check!(expected_type_struct_field_followed_by_comma);
1536         check_expected_type_and_name(
1537             r#"
1538 struct Foo { a: u32 }
1539 fn foo() {
1540     Foo { a: $0, };
1541 }
1542 "#,
1543             expect![[r#"ty: u32, name: a"#]],
1544         )
1545     }
1546
1547     #[test]
1548     fn expected_type_generic_struct_field() {
1549         check_expected_type_and_name(
1550             r#"
1551 struct Foo<T> { a: T }
1552 fn foo() -> Foo<u32> {
1553     Foo { a: $0 }
1554 }
1555 "#,
1556             expect![[r#"ty: u32, name: a"#]],
1557         )
1558     }
1559
1560     #[test]
1561     fn expected_type_struct_field_with_leading_char() {
1562         cov_mark::check!(expected_type_struct_field_with_leading_char);
1563         check_expected_type_and_name(
1564             r#"
1565 struct Foo { a: u32 }
1566 fn foo() {
1567     Foo { a: c$0 };
1568 }
1569 "#,
1570             expect![[r#"ty: u32, name: a"#]],
1571         );
1572     }
1573
1574     #[test]
1575     fn expected_type_match_arm_without_leading_char() {
1576         cov_mark::check!(expected_type_match_arm_without_leading_char);
1577         check_expected_type_and_name(
1578             r#"
1579 enum E { X }
1580 fn foo() {
1581    match E::X { $0 }
1582 }
1583 "#,
1584             expect![[r#"ty: E, name: ?"#]],
1585         );
1586     }
1587
1588     #[test]
1589     fn expected_type_match_arm_with_leading_char() {
1590         cov_mark::check!(expected_type_match_arm_with_leading_char);
1591         check_expected_type_and_name(
1592             r#"
1593 enum E { X }
1594 fn foo() {
1595    match E::X { c$0 }
1596 }
1597 "#,
1598             expect![[r#"ty: E, name: ?"#]],
1599         );
1600     }
1601
1602     #[test]
1603     fn expected_type_match_arm_body_without_leading_char() {
1604         cov_mark::check!(expected_type_match_arm_body_without_leading_char);
1605         check_expected_type_and_name(
1606             r#"
1607 struct Foo;
1608 enum E { X }
1609 fn foo() -> Foo {
1610    match E::X { E::X => $0 }
1611 }
1612 "#,
1613             expect![[r#"ty: Foo, name: ?"#]],
1614         );
1615     }
1616
1617     #[test]
1618     fn expected_type_match_body_arm_with_leading_char() {
1619         cov_mark::check!(expected_type_match_arm_body_with_leading_char);
1620         check_expected_type_and_name(
1621             r#"
1622 struct Foo;
1623 enum E { X }
1624 fn foo() -> Foo {
1625    match E::X { E::X => c$0 }
1626 }
1627 "#,
1628             expect![[r#"ty: Foo, name: ?"#]],
1629         );
1630     }
1631
1632     #[test]
1633     fn expected_type_if_let_without_leading_char() {
1634         cov_mark::check!(expected_type_if_let_without_leading_char);
1635         check_expected_type_and_name(
1636             r#"
1637 enum Foo { Bar, Baz, Quux }
1638
1639 fn foo() {
1640     let f = Foo::Quux;
1641     if let $0 = f { }
1642 }
1643 "#,
1644             expect![[r#"ty: Foo, name: ?"#]],
1645         )
1646     }
1647
1648     #[test]
1649     fn expected_type_if_let_with_leading_char() {
1650         cov_mark::check!(expected_type_if_let_with_leading_char);
1651         check_expected_type_and_name(
1652             r#"
1653 enum Foo { Bar, Baz, Quux }
1654
1655 fn foo() {
1656     let f = Foo::Quux;
1657     if let c$0 = f { }
1658 }
1659 "#,
1660             expect![[r#"ty: Foo, name: ?"#]],
1661         )
1662     }
1663
1664     #[test]
1665     fn expected_type_fn_ret_without_leading_char() {
1666         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1667         check_expected_type_and_name(
1668             r#"
1669 fn foo() -> u32 {
1670     $0
1671 }
1672 "#,
1673             expect![[r#"ty: u32, name: ?"#]],
1674         )
1675     }
1676
1677     #[test]
1678     fn expected_type_fn_ret_with_leading_char() {
1679         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1680         check_expected_type_and_name(
1681             r#"
1682 fn foo() -> u32 {
1683     c$0
1684 }
1685 "#,
1686             expect![[r#"ty: u32, name: ?"#]],
1687         )
1688     }
1689
1690     #[test]
1691     fn expected_type_fn_ret_fn_ref_fully_typed() {
1692         check_expected_type_and_name(
1693             r#"
1694 fn foo() -> u32 {
1695     foo$0
1696 }
1697 "#,
1698             expect![[r#"ty: u32, name: ?"#]],
1699         )
1700     }
1701
1702     #[test]
1703     fn expected_type_closure_param_return() {
1704         // FIXME: make this work with `|| $0`
1705         check_expected_type_and_name(
1706             r#"
1707 //- minicore: fn
1708 fn foo() {
1709     bar(|| a$0);
1710 }
1711
1712 fn bar(f: impl FnOnce() -> u32) {}
1713 "#,
1714             expect![[r#"ty: u32, name: ?"#]],
1715         );
1716     }
1717
1718     #[test]
1719     fn expected_type_generic_function() {
1720         check_expected_type_and_name(
1721             r#"
1722 fn foo() {
1723     bar::<u32>($0);
1724 }
1725
1726 fn bar<T>(t: T) {}
1727 "#,
1728             expect![[r#"ty: u32, name: t"#]],
1729         );
1730     }
1731
1732     #[test]
1733     fn expected_type_generic_method() {
1734         check_expected_type_and_name(
1735             r#"
1736 fn foo() {
1737     S(1u32).bar($0);
1738 }
1739
1740 struct S<T>(T);
1741 impl<T> S<T> {
1742     fn bar(self, t: T) {}
1743 }
1744 "#,
1745             expect![[r#"ty: u32, name: t"#]],
1746         );
1747     }
1748
1749     #[test]
1750     fn expected_type_functional_update() {
1751         cov_mark::check!(expected_type_struct_func_update);
1752         check_expected_type_and_name(
1753             r#"
1754 struct Foo { field: u32 }
1755 fn foo() {
1756     Foo {
1757         ..$0
1758     }
1759 }
1760 "#,
1761             expect![[r#"ty: Foo, name: ?"#]],
1762         );
1763     }
1764
1765     #[test]
1766     fn expected_type_param_pat() {
1767         check_expected_type_and_name(
1768             r#"
1769 struct Foo { field: u32 }
1770 fn foo(a$0: Foo) {}
1771 "#,
1772             expect![[r#"ty: Foo, name: ?"#]],
1773         );
1774         check_expected_type_and_name(
1775             r#"
1776 struct Foo { field: u32 }
1777 fn foo($0: Foo) {}
1778 "#,
1779             // FIXME make this work, currently fails due to pattern recovery eating the `:`
1780             expect![[r#"ty: ?, name: ?"#]],
1781         );
1782     }
1783 }