crates/ide_completion/src/context.rs

   1 //! See `CompletionContext` structure.
   2
   3 use base_db::SourceDatabaseExt;
   4 use hir::{Local, Name, ScopeDef, Semantics, SemanticsScope, Type};
   5 use ide_db::{
   6     base_db::{FilePosition, SourceDatabase},
   7     call_info::ActiveParameter,
   8     RootDatabase,
   9 };
  10 use syntax::{
  11     algo::find_node_at_offset,
  12     ast::{self, NameOrNameRef, NameOwner},
  13     match_ast, AstNode, NodeOrToken,
  14     SyntaxKind::{self, *},
  15     SyntaxNode, SyntaxToken, TextRange, TextSize, T,
  16 };
  17 use text_edit::Indel;
  18
  19 use crate::{
  20     patterns::{
  21         determine_location, determine_prev_sibling, for_is_prev2, inside_impl_trait_block,
  22         is_in_loop_body, previous_token, ImmediateLocation, ImmediatePrevSibling,
  23     },
  24     CompletionConfig,
  25 };
  26
  27 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  28 pub(crate) enum PatternRefutability {
  29     Refutable,
  30     Irrefutable,
  31 }
  32
  33 #[derive(Debug)]
  34 pub(super) enum PathKind {
  35     Expr,
  36     Type,
  37 }
  38
  39 #[derive(Debug)]
  40 pub(crate) struct PathCompletionContext {
  41     /// If this is a call with () already there
  42     call_kind: Option<CallKind>,
  43     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  44     pub(super) is_trivial_path: bool,
  45     /// If not a trivial path, the prefix (qualifier).
  46     pub(super) qualifier: Option<ast::Path>,
  47     /// Whether the qualifier comes from a use tree parent or not
  48     pub(super) use_tree_parent: bool,
  49     pub(super) kind: Option<PathKind>,
  50     /// Whether the path segment has type args or not.
  51     pub(super) has_type_args: bool,
  52     /// `true` if we are a statement or a last expr in the block.
  53     pub(super) can_be_stmt: bool,
  54     pub(super) in_loop_body: bool,
  55 }
  56
  57 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  58 pub(crate) enum CallKind {
  59     Pat,
  60     Mac,
  61     Expr,
  62 }
  63 /// `CompletionContext` is created early during completion to figure out, where
  64 /// exactly is the cursor, syntax-wise.
  65 #[derive(Debug)]
  66 pub(crate) struct CompletionContext<'a> {
  67     pub(super) sema: Semantics<'a, RootDatabase>,
  68     pub(super) scope: SemanticsScope<'a>,
  69     pub(super) db: &'a RootDatabase,
  70     pub(super) config: &'a CompletionConfig,
  71     pub(super) position: FilePosition,
  72     /// The token before the cursor, in the original file.
  73     pub(super) original_token: SyntaxToken,
  74     /// The token before the cursor, in the macro-expanded file.
  75     pub(super) token: SyntaxToken,
  76     pub(super) krate: Option<hir::Crate>,
  77     pub(super) expected_name: Option<NameOrNameRef>,
  78     pub(super) expected_type: Option<Type>,
  79
  80     /// The parent function of the cursor position if it exists.
  81     pub(super) function_def: Option<ast::Fn>,
  82     /// The parent impl of the cursor position if it exists.
  83     pub(super) impl_def: Option<ast::Impl>,
  84     pub(super) name_ref_syntax: Option<ast::NameRef>,
  85
  86     // potentially set if we are completing a lifetime
  87     pub(super) lifetime_syntax: Option<ast::Lifetime>,
  88     pub(super) lifetime_param_syntax: Option<ast::LifetimeParam>,
  89     pub(super) lifetime_allowed: bool,
  90     pub(super) is_label_ref: bool,
  91
  92     // potentially set if we are completing a name
  93     pub(super) is_pat_or_const: Option<PatternRefutability>,
  94     pub(super) is_param: bool,
  95
  96     pub(super) completion_location: Option<ImmediateLocation>,
  97     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
  98     pub(super) attribute_under_caret: Option<ast::Attr>,
  99     pub(super) previous_token: Option<SyntaxToken>,
 100
 101     pub(super) path_context: Option<PathCompletionContext>,
 102     pub(super) active_parameter: Option<ActiveParameter>,
 103     pub(super) locals: Vec<(String, Local)>,
 104
 105     pub(super) incomplete_let: bool,
 106
 107     no_completion_required: bool,
 108 }
 109
 110 impl<'a> CompletionContext<'a> {
 111     pub(super) fn new(
 112         db: &'a RootDatabase,
 113         position: FilePosition,
 114         config: &'a CompletionConfig,
 115     ) -> Option<CompletionContext<'a>> {
 116         let sema = Semantics::new(db);
 117
 118         let original_file = sema.parse(position.file_id);
 119
 120         // Insert a fake ident to get a valid parse tree. We will use this file
 121         // to determine context, though the original_file will be used for
 122         // actual completion.
 123         let file_with_fake_ident = {
 124             let parse = db.parse(position.file_id);
 125             let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
 126             parse.reparse(&edit).tree()
 127         };
 128         let fake_ident_token =
 129             file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 130
 131         let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
 132         let original_token =
 133             original_file.syntax().token_at_offset(position.offset).left_biased()?;
 134         let token = sema.descend_into_macros(original_token.clone());
 135         let scope = sema.scope_at_offset(&token, position.offset);
 136         let mut locals = vec![];
 137         scope.process_all_names(&mut |name, scope| {
 138             if let ScopeDef::Local(local) = scope {
 139                 locals.push((name.to_string(), local));
 140             }
 141         });
 142         let mut ctx = CompletionContext {
 143             sema,
 144             scope,
 145             db,
 146             config,
 147             position,
 148             original_token,
 149             token,
 150             krate,
 151             expected_name: None,
 152             expected_type: None,
 153             function_def: None,
 154             impl_def: None,
 155             name_ref_syntax: None,
 156             lifetime_syntax: None,
 157             lifetime_param_syntax: None,
 158             lifetime_allowed: false,
 159             is_label_ref: false,
 160             is_pat_or_const: None,
 161             is_param: false,
 162             completion_location: None,
 163             prev_sibling: None,
 164             attribute_under_caret: None,
 165             previous_token: None,
 166             path_context: None,
 167             active_parameter: ActiveParameter::at(db, position),
 168             locals,
 169             incomplete_let: false,
 170             no_completion_required: false,
 171         };
 172
 173         let mut original_file = original_file.syntax().clone();
 174         let mut speculative_file = file_with_fake_ident.syntax().clone();
 175         let mut offset = position.offset;
 176         let mut fake_ident_token = fake_ident_token;
 177
 178         // Are we inside a macro call?
 179         while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 180             find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 181             find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 182         ) {
 183             if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
 184                 != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
 185             {
 186                 break;
 187             }
 188             let speculative_args = match macro_call_with_fake_ident.token_tree() {
 189                 Some(tt) => tt,
 190                 None => break,
 191             };
 192             if let (Some(actual_expansion), Some(speculative_expansion)) = (
 193                 ctx.sema.expand(&actual_macro_call),
 194                 ctx.sema.speculative_expand(
 195                     &actual_macro_call,
 196                     &speculative_args,
 197                     fake_ident_token,
 198                 ),
 199             ) {
 200                 let new_offset = speculative_expansion.1.text_range().start();
 201                 if new_offset > actual_expansion.text_range().end() {
 202                     break;
 203                 }
 204                 original_file = actual_expansion;
 205                 speculative_file = speculative_expansion.0;
 206                 fake_ident_token = speculative_expansion.1;
 207                 offset = new_offset;
 208             } else {
 209                 break;
 210             }
 211         }
 212         ctx.fill(&original_file, speculative_file, offset);
 213         Some(ctx)
 214     }
 215
 216     /// Checks whether completions in that particular case don't make much sense.
 217     /// Examples:
 218     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 219     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 220     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 221     pub(crate) fn no_completion_required(&self) -> bool {
 222         self.no_completion_required
 223     }
 224
 225     /// The range of the identifier that is being completed.
 226     pub(crate) fn source_range(&self) -> TextRange {
 227         // check kind of macro-expanded token, but use range of original token
 228         let kind = self.token.kind();
 229         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 230             cov_mark::hit!(completes_if_prefix_is_keyword);
 231             self.original_token.text_range()
 232         } else if kind == CHAR {
 233             // assume we are completing a lifetime but the user has only typed the '
 234             cov_mark::hit!(completes_if_lifetime_without_idents);
 235             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 236         } else {
 237             TextRange::empty(self.position.offset)
 238         }
 239     }
 240
 241     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 242         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 243     }
 244
 245     pub(crate) fn expects_assoc_item(&self) -> bool {
 246         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 247     }
 248
 249     pub(crate) fn has_dot_receiver(&self) -> bool {
 250         matches!(
 251             &self.completion_location,
 252             Some(ImmediateLocation::FieldAccess { receiver, .. } | ImmediateLocation::MethodCall { receiver,.. })
 253                 if receiver.is_some()
 254         )
 255     }
 256
 257     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 258         match &self.completion_location {
 259             Some(
 260                 ImmediateLocation::MethodCall { receiver, .. }
 261                 | ImmediateLocation::FieldAccess { receiver, .. },
 262             ) => receiver.as_ref(),
 263             _ => None,
 264         }
 265     }
 266
 267     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 268         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 269     }
 270
 271     pub(crate) fn expects_item(&self) -> bool {
 272         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 273     }
 274
 275     pub(crate) fn expects_generic_arg(&self) -> bool {
 276         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 277     }
 278
 279     pub(crate) fn has_block_expr_parent(&self) -> bool {
 280         matches!(self.completion_location, Some(ImmediateLocation::BlockExpr))
 281     }
 282
 283     pub(crate) fn expects_ident_pat_or_ref_expr(&self) -> bool {
 284         matches!(
 285             self.completion_location,
 286             Some(ImmediateLocation::IdentPat | ImmediateLocation::RefExpr)
 287         )
 288     }
 289
 290     pub(crate) fn expect_field(&self) -> bool {
 291         matches!(
 292             self.completion_location,
 293             Some(ImmediateLocation::RecordField | ImmediateLocation::TupleField)
 294         )
 295     }
 296
 297     pub(crate) fn in_use_tree(&self) -> bool {
 298         matches!(
 299             self.completion_location,
 300             Some(ImmediateLocation::Use | ImmediateLocation::UseTree)
 301         )
 302     }
 303
 304     pub(crate) fn has_impl_or_trait_prev_sibling(&self) -> bool {
 305         matches!(
 306             self.prev_sibling,
 307             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 308         )
 309     }
 310
 311     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 312         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 313     }
 314
 315     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 316         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 317     }
 318
 319     pub(crate) fn after_if(&self) -> bool {
 320         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 321     }
 322
 323     pub(crate) fn is_path_disallowed(&self) -> bool {
 324         self.attribute_under_caret.is_some()
 325             || self.previous_token_is(T![unsafe])
 326             || matches!(
 327                 self.prev_sibling,
 328                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 329             )
 330             || matches!(
 331                 self.completion_location,
 332                 Some(
 333                     ImmediateLocation::Attribute(_)
 334                         | ImmediateLocation::ModDeclaration(_)
 335                         | ImmediateLocation::RecordPat(_)
 336                         | ImmediateLocation::RecordExpr(_)
 337                 )
 338             )
 339     }
 340
 341     pub(crate) fn expects_expression(&self) -> bool {
 342         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Expr), .. }))
 343     }
 344
 345     pub(crate) fn expects_type(&self) -> bool {
 346         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Type), .. }))
 347     }
 348
 349     pub(crate) fn path_call_kind(&self) -> Option<CallKind> {
 350         self.path_context.as_ref().and_then(|it| it.call_kind)
 351     }
 352
 353     pub(crate) fn is_trivial_path(&self) -> bool {
 354         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: true, .. }))
 355     }
 356
 357     pub(crate) fn is_non_trivial_path(&self) -> bool {
 358         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: false, .. }))
 359     }
 360
 361     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 362         self.path_context.as_ref().and_then(|it| it.qualifier.as_ref())
 363     }
 364
 365     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 366     pub(crate) fn is_visible<I>(&self, item: &I) -> bool
 367     where
 368         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 369     {
 370         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 371     }
 372
 373     pub(crate) fn is_scope_def_hidden(&self, scope_def: &ScopeDef) -> bool {
 374         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 375             return self.is_doc_hidden(&attrs, krate);
 376         }
 377
 378         false
 379     }
 380
 381     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 382     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 383         self.scope.process_all_names(&mut |name, def| {
 384             if self.is_scope_def_hidden(&def) {
 385                 return;
 386             }
 387
 388             f(name, def);
 389         })
 390     }
 391
 392     fn is_visible_impl(
 393         &self,
 394         vis: &hir::Visibility,
 395         attrs: &hir::Attrs,
 396         defining_crate: hir::Crate,
 397     ) -> bool {
 398         let module = match self.scope.module() {
 399             Some(it) => it,
 400             None => return false,
 401         };
 402         if !vis.is_visible_from(self.db, module.into()) {
 403             // If the definition location is editable, also show private items
 404             let root_file = defining_crate.root_file(self.db);
 405             let source_root_id = self.db.file_source_root(root_file);
 406             let is_editable = !self.db.source_root(source_root_id).is_library;
 407             return is_editable;
 408         }
 409
 410         !self.is_doc_hidden(attrs, defining_crate)
 411     }
 412
 413     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 414         let module = match self.scope.module() {
 415             Some(it) => it,
 416             None => return true,
 417         };
 418         if module.krate() != defining_crate && attrs.has_doc_hidden() {
 419             // `doc(hidden)` items are only completed within the defining crate.
 420             return true;
 421         }
 422
 423         false
 424     }
 425
 426     fn fill_impl_def(&mut self) {
 427         self.impl_def = self
 428             .sema
 429             .token_ancestors_with_macros(self.token.clone())
 430             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 431             .find_map(ast::Impl::cast);
 432     }
 433
 434     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 435         let mut node = match self.token.parent() {
 436             Some(it) => it,
 437             None => return (None, None),
 438         };
 439         loop {
 440             break match_ast! {
 441                 match node {
 442                     ast::LetStmt(it) => {
 443                         cov_mark::hit!(expected_type_let_with_leading_char);
 444                         cov_mark::hit!(expected_type_let_without_leading_char);
 445                         let ty = it.pat()
 446                             .and_then(|pat| self.sema.type_of_pat(&pat))
 447                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)));
 448                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 449                             ident.name().map(NameOrNameRef::Name)
 450                         } else {
 451                             None
 452                         };
 453
 454                         (ty, name)
 455                     },
 456                     ast::ArgList(_it) => {
 457                         cov_mark::hit!(expected_type_fn_param);
 458                         ActiveParameter::at_token(
 459                             &self.sema,
 460                             self.token.clone(),
 461                         ).map(|ap| {
 462                             let name = ap.ident().map(NameOrNameRef::Name);
 463                             let ty = if has_ref(&self.token) {
 464                                 cov_mark::hit!(expected_type_fn_param_ref);
 465                                 ap.ty.remove_ref()
 466                             } else {
 467                                 Some(ap.ty)
 468                             };
 469                             (ty, name)
 470                         })
 471                         .unwrap_or((None, None))
 472                     },
 473                     ast::RecordExprFieldList(_it) => {
 474                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
 475                         // wouldn't try {} be nice...
 476                         (|| {
 477                             let expr_field = self.token.prev_sibling_or_token()?
 478                                       .into_node()
 479                                       .and_then(ast::RecordExprField::cast)?;
 480                             let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 481                             Some((
 482                                 Some(ty),
 483                                 expr_field.field_name().map(NameOrNameRef::NameRef),
 484                             ))
 485                         })().unwrap_or((None, None))
 486                     },
 487                     ast::RecordExprField(it) => {
 488                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 489                         (
 490                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)),
 491                             it.field_name().map(NameOrNameRef::NameRef),
 492                         )
 493                     },
 494                     ast::MatchExpr(it) => {
 495                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 496                         let ty = it.expr()
 497                             .and_then(|e| self.sema.type_of_expr(&e));
 498                         (ty, None)
 499                     },
 500                     ast::IfExpr(it) => {
 501                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 502                         let ty = it.condition()
 503                             .and_then(|cond| cond.expr())
 504                             .and_then(|e| self.sema.type_of_expr(&e));
 505                         (ty, None)
 506                     },
 507                     ast::IdentPat(it) => {
 508                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 509                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 510                         let ty = self.sema.type_of_pat(&ast::Pat::from(it));
 511                         (ty, None)
 512                     },
 513                     ast::Fn(it) => {
 514                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 515                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 516                         let def = self.sema.to_def(&it);
 517                         (def.map(|def| def.ret_type(self.db)), None)
 518                     },
 519                     ast::ClosureExpr(it) => {
 520                         let ty = self.sema.type_of_expr(&it.into());
 521                         ty.and_then(|ty| ty.as_callable(self.db))
 522                             .map(|c| (Some(c.return_type()), None))
 523                             .unwrap_or((None, None))
 524                     },
 525                     ast::Stmt(_it) => (None, None),
 526                     _ => {
 527                         match node.parent() {
 528                             Some(n) => {
 529                                 node = n;
 530                                 continue;
 531                             },
 532                             None => (None, None),
 533                         }
 534                     },
 535                 }
 536             };
 537         }
 538     }
 539
 540     fn fill(
 541         &mut self,
 542         original_file: &SyntaxNode,
 543         file_with_fake_ident: SyntaxNode,
 544         offset: TextSize,
 545     ) {
 546         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 547         let syntax_element = NodeOrToken::Token(fake_ident_token);
 548         self.previous_token = previous_token(syntax_element.clone());
 549         self.attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
 550         self.no_completion_required = {
 551             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 552             let fn_is_prev = self.previous_token_is(T![fn]);
 553             let for_is_prev2 = for_is_prev2(syntax_element.clone());
 554             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
 555         };
 556
 557         self.incomplete_let =
 558             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 559                 it.syntax().text_range().end() == syntax_element.text_range().end()
 560             });
 561
 562         let (expected_type, expected_name) = self.expected_type_and_name();
 563         self.expected_type = expected_type;
 564         self.expected_name = expected_name;
 565
 566         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 567             Some(it) => it,
 568             None => return,
 569         };
 570         self.completion_location =
 571             determine_location(&self.sema, original_file, offset, &name_like);
 572         self.prev_sibling = determine_prev_sibling(&name_like);
 573         match name_like {
 574             ast::NameLike::Lifetime(lifetime) => {
 575                 self.classify_lifetime(original_file, lifetime, offset);
 576             }
 577             ast::NameLike::NameRef(name_ref) => {
 578                 self.classify_name_ref(original_file, name_ref);
 579             }
 580             ast::NameLike::Name(name) => {
 581                 self.classify_name(name);
 582             }
 583         }
 584     }
 585
 586     fn classify_lifetime(
 587         &mut self,
 588         original_file: &SyntaxNode,
 589         lifetime: ast::Lifetime,
 590         offset: TextSize,
 591     ) {
 592         self.lifetime_syntax =
 593             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 594         if let Some(parent) = lifetime.syntax().parent() {
 595             if parent.kind() == ERROR {
 596                 return;
 597             }
 598
 599             match_ast! {
 600                 match parent {
 601                     ast::LifetimeParam(_it) => {
 602                         self.lifetime_allowed = true;
 603                         self.lifetime_param_syntax =
 604                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 605                     },
 606                     ast::BreakExpr(_it) => self.is_label_ref = true,
 607                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 608                     ast::Label(_it) => (),
 609                     _ => self.lifetime_allowed = true,
 610                 }
 611             }
 612         }
 613     }
 614
 615     fn classify_name(&mut self, name: ast::Name) {
 616         if let Some(bind_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
 617             self.is_pat_or_const = Some(PatternRefutability::Refutable);
 618             // if any of these is here our bind pat can't be a const pat anymore
 619             let complex_ident_pat = bind_pat.at_token().is_some()
 620                 || bind_pat.ref_token().is_some()
 621                 || bind_pat.mut_token().is_some();
 622             if complex_ident_pat {
 623                 self.is_pat_or_const = None;
 624             } else {
 625                 let irrefutable_pat = bind_pat.syntax().ancestors().find_map(|node| {
 626                     match_ast! {
 627                         match node {
 628                             ast::LetStmt(it) => Some(it.pat()),
 629                             ast::Param(it) => Some(it.pat()),
 630                             _ => None,
 631                         }
 632                     }
 633                 });
 634                 if let Some(Some(pat)) = irrefutable_pat {
 635                     // This check is here since we could be inside a pattern in the initializer expression of the let statement.
 636                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 637                         self.is_pat_or_const = Some(PatternRefutability::Irrefutable);
 638                     }
 639                 }
 640
 641                 let is_name_in_field_pat = bind_pat
 642                     .syntax()
 643                     .parent()
 644                     .and_then(ast::RecordPatField::cast)
 645                     .map_or(false, |pat_field| pat_field.name_ref().is_none());
 646                 if is_name_in_field_pat {
 647                     self.is_pat_or_const = None;
 648                 }
 649             }
 650
 651             self.fill_impl_def();
 652         }
 653
 654         self.is_param |= is_node::<ast::Param>(name.syntax());
 655     }
 656
 657     fn classify_name_ref(&mut self, original_file: &SyntaxNode, name_ref: ast::NameRef) {
 658         self.fill_impl_def();
 659
 660         self.name_ref_syntax =
 661             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 662
 663         self.function_def = self
 664             .sema
 665             .token_ancestors_with_macros(self.token.clone())
 666             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 667             .find_map(ast::Fn::cast);
 668
 669         let parent = match name_ref.syntax().parent() {
 670             Some(it) => it,
 671             None => return,
 672         };
 673
 674         if let Some(segment) = ast::PathSegment::cast(parent) {
 675             let path_ctx = self.path_context.get_or_insert(PathCompletionContext {
 676                 call_kind: None,
 677                 is_trivial_path: false,
 678                 qualifier: None,
 679                 has_type_args: false,
 680                 can_be_stmt: false,
 681                 in_loop_body: false,
 682                 use_tree_parent: false,
 683                 kind: None,
 684             });
 685             path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
 686             let path = segment.parent_path();
 687
 688             if let Some(p) = path.syntax().parent() {
 689                 path_ctx.call_kind = match_ast! {
 690                     match p {
 691                         ast::PathExpr(it) => it.syntax().parent().and_then(ast::CallExpr::cast).map(|_| CallKind::Expr),
 692                         ast::MacroCall(it) => it.excl_token().and(Some(CallKind::Mac)),
 693                         ast::TupleStructPat(_it) => Some(CallKind::Pat),
 694                         _ => None
 695                     }
 696                 };
 697             }
 698
 699             if let Some(parent) = path.syntax().parent() {
 700                 path_ctx.kind = match_ast! {
 701                     match parent {
 702                         ast::PathType(_it) => Some(PathKind::Type),
 703                         ast::PathExpr(_it) => Some(PathKind::Expr),
 704                         _ => None,
 705                     }
 706                 };
 707             }
 708             path_ctx.has_type_args = segment.generic_arg_list().is_some();
 709
 710             if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
 711                 path_ctx.use_tree_parent = use_tree_parent;
 712                 path_ctx.qualifier = path
 713                     .segment()
 714                     .and_then(|it| {
 715                         find_node_with_range::<ast::PathSegment>(
 716                             original_file,
 717                             it.syntax().text_range(),
 718                         )
 719                     })
 720                     .map(|it| it.parent_path());
 721                 return;
 722             }
 723
 724             if let Some(segment) = path.segment() {
 725                 if segment.coloncolon_token().is_some() {
 726                     return;
 727                 }
 728             }
 729
 730             path_ctx.is_trivial_path = true;
 731
 732             // Find either enclosing expr statement (thing with `;`) or a
 733             // block. If block, check that we are the last expr.
 734             path_ctx.can_be_stmt = name_ref
 735                 .syntax()
 736                 .ancestors()
 737                 .find_map(|node| {
 738                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 739                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 740                     }
 741                     if let Some(block) = ast::BlockExpr::cast(node) {
 742                         return Some(
 743                             block.tail_expr().map(|e| e.syntax().text_range())
 744                                 == Some(name_ref.syntax().text_range()),
 745                         );
 746                     }
 747                     None
 748                 })
 749                 .unwrap_or(false);
 750         }
 751     }
 752 }
 753
 754 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 755     syntax.covering_element(range).ancestors().find_map(N::cast)
 756 }
 757
 758 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 759     match node.ancestors().find_map(N::cast) {
 760         None => false,
 761         Some(n) => n.syntax().text_range() == node.text_range(),
 762     }
 763 }
 764
 765 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
 766     if let Some(qual) = path.qualifier() {
 767         return Some((qual, false));
 768     }
 769     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 770     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 771     use_tree.path().zip(Some(true))
 772 }
 773
 774 fn has_ref(token: &SyntaxToken) -> bool {
 775     let mut token = token.clone();
 776     for skip in [WHITESPACE, IDENT, T![mut]] {
 777         if token.kind() == skip {
 778             token = match token.prev_token() {
 779                 Some(it) => it,
 780                 None => return false,
 781             }
 782         }
 783     }
 784     token.kind() == T![&]
 785 }
 786
 787 #[cfg(test)]
 788 mod tests {
 789     use expect_test::{expect, Expect};
 790     use hir::HirDisplay;
 791
 792     use crate::tests::{position, TEST_CONFIG};
 793
 794     use super::CompletionContext;
 795
 796     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 797         let (db, pos) = position(ra_fixture);
 798         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 799
 800         let ty = completion_context
 801             .expected_type
 802             .map(|t| t.display_test(&db).to_string())
 803             .unwrap_or("?".to_owned());
 804
 805         let name = completion_context
 806             .expected_name
 807             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 808
 809         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 810     }
 811
 812     #[test]
 813     fn expected_type_let_without_leading_char() {
 814         cov_mark::check!(expected_type_let_without_leading_char);
 815         check_expected_type_and_name(
 816             r#"
 817 fn foo() {
 818     let x: u32 = $0;
 819 }
 820 "#,
 821             expect![[r#"ty: u32, name: x"#]],
 822         );
 823     }
 824
 825     #[test]
 826     fn expected_type_let_with_leading_char() {
 827         cov_mark::check!(expected_type_let_with_leading_char);
 828         check_expected_type_and_name(
 829             r#"
 830 fn foo() {
 831     let x: u32 = c$0;
 832 }
 833 "#,
 834             expect![[r#"ty: u32, name: x"#]],
 835         );
 836     }
 837
 838     #[test]
 839     fn expected_type_let_pat() {
 840         check_expected_type_and_name(
 841             r#"
 842 fn foo() {
 843     let x$0 = 0u32;
 844 }
 845 "#,
 846             expect![[r#"ty: u32, name: ?"#]],
 847         );
 848         check_expected_type_and_name(
 849             r#"
 850 fn foo() {
 851     let $0 = 0u32;
 852 }
 853 "#,
 854             expect![[r#"ty: u32, name: ?"#]],
 855         );
 856     }
 857
 858     #[test]
 859     fn expected_type_fn_param() {
 860         cov_mark::check!(expected_type_fn_param);
 861         check_expected_type_and_name(
 862             r#"
 863 fn foo() { bar($0); }
 864 fn bar(x: u32) {}
 865 "#,
 866             expect![[r#"ty: u32, name: x"#]],
 867         );
 868         check_expected_type_and_name(
 869             r#"
 870 fn foo() { bar(c$0); }
 871 fn bar(x: u32) {}
 872 "#,
 873             expect![[r#"ty: u32, name: x"#]],
 874         );
 875     }
 876
 877     #[test]
 878     fn expected_type_fn_param_ref() {
 879         cov_mark::check!(expected_type_fn_param_ref);
 880         check_expected_type_and_name(
 881             r#"
 882 fn foo() { bar(&$0); }
 883 fn bar(x: &u32) {}
 884 "#,
 885             expect![[r#"ty: u32, name: x"#]],
 886         );
 887         check_expected_type_and_name(
 888             r#"
 889 fn foo() { bar(&mut $0); }
 890 fn bar(x: &mut u32) {}
 891 "#,
 892             expect![[r#"ty: u32, name: x"#]],
 893         );
 894         check_expected_type_and_name(
 895             r#"
 896 fn foo() { bar(&c$0); }
 897 fn bar(x: &u32) {}
 898         "#,
 899             expect![[r#"ty: u32, name: x"#]],
 900         );
 901     }
 902
 903     #[test]
 904     fn expected_type_struct_field_without_leading_char() {
 905         cov_mark::check!(expected_type_struct_field_without_leading_char);
 906         check_expected_type_and_name(
 907             r#"
 908 struct Foo { a: u32 }
 909 fn foo() {
 910     Foo { a: $0 };
 911 }
 912 "#,
 913             expect![[r#"ty: u32, name: a"#]],
 914         )
 915     }
 916
 917     #[test]
 918     fn expected_type_generic_struct_field() {
 919         check_expected_type_and_name(
 920             r#"
 921 struct Foo<T> { a: T }
 922 fn foo() -> Foo<u32> {
 923     Foo { a: $0 }
 924 }
 925 "#,
 926             expect![[r#"ty: u32, name: a"#]],
 927         )
 928     }
 929
 930     #[test]
 931     fn expected_type_struct_field_with_leading_char() {
 932         cov_mark::check!(expected_type_struct_field_with_leading_char);
 933         check_expected_type_and_name(
 934             r#"
 935 struct Foo { a: u32 }
 936 fn foo() {
 937     Foo { a: c$0 };
 938 }
 939 "#,
 940             expect![[r#"ty: u32, name: a"#]],
 941         );
 942     }
 943
 944     #[test]
 945     fn expected_type_match_arm_without_leading_char() {
 946         cov_mark::check!(expected_type_match_arm_without_leading_char);
 947         check_expected_type_and_name(
 948             r#"
 949 enum E { X }
 950 fn foo() {
 951    match E::X { $0 }
 952 }
 953 "#,
 954             expect![[r#"ty: E, name: ?"#]],
 955         );
 956     }
 957
 958     #[test]
 959     fn expected_type_match_arm_with_leading_char() {
 960         cov_mark::check!(expected_type_match_arm_with_leading_char);
 961         check_expected_type_and_name(
 962             r#"
 963 enum E { X }
 964 fn foo() {
 965    match E::X { c$0 }
 966 }
 967 "#,
 968             expect![[r#"ty: E, name: ?"#]],
 969         );
 970     }
 971
 972     #[test]
 973     fn expected_type_if_let_without_leading_char() {
 974         cov_mark::check!(expected_type_if_let_without_leading_char);
 975         check_expected_type_and_name(
 976             r#"
 977 enum Foo { Bar, Baz, Quux }
 978
 979 fn foo() {
 980     let f = Foo::Quux;
 981     if let $0 = f { }
 982 }
 983 "#,
 984             expect![[r#"ty: Foo, name: ?"#]],
 985         )
 986     }
 987
 988     #[test]
 989     fn expected_type_if_let_with_leading_char() {
 990         cov_mark::check!(expected_type_if_let_with_leading_char);
 991         check_expected_type_and_name(
 992             r#"
 993 enum Foo { Bar, Baz, Quux }
 994
 995 fn foo() {
 996     let f = Foo::Quux;
 997     if let c$0 = f { }
 998 }
 999 "#,
1000             expect![[r#"ty: Foo, name: ?"#]],
1001         )
1002     }
1003
1004     #[test]
1005     fn expected_type_fn_ret_without_leading_char() {
1006         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1007         check_expected_type_and_name(
1008             r#"
1009 fn foo() -> u32 {
1010     $0
1011 }
1012 "#,
1013             expect![[r#"ty: u32, name: ?"#]],
1014         )
1015     }
1016
1017     #[test]
1018     fn expected_type_fn_ret_with_leading_char() {
1019         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1020         check_expected_type_and_name(
1021             r#"
1022 fn foo() -> u32 {
1023     c$0
1024 }
1025 "#,
1026             expect![[r#"ty: u32, name: ?"#]],
1027         )
1028     }
1029
1030     #[test]
1031     fn expected_type_fn_ret_fn_ref_fully_typed() {
1032         check_expected_type_and_name(
1033             r#"
1034 fn foo() -> u32 {
1035     foo$0
1036 }
1037 "#,
1038             expect![[r#"ty: u32, name: ?"#]],
1039         )
1040     }
1041
1042     #[test]
1043     fn expected_type_closure_param_return() {
1044         // FIXME: make this work with `|| $0`
1045         check_expected_type_and_name(
1046             r#"
1047 //- minicore: fn
1048 fn foo() {
1049     bar(|| a$0);
1050 }
1051
1052 fn bar(f: impl FnOnce() -> u32) {}
1053 "#,
1054             expect![[r#"ty: u32, name: ?"#]],
1055         );
1056     }
1057
1058     #[test]
1059     fn expected_type_generic_function() {
1060         check_expected_type_and_name(
1061             r#"
1062 fn foo() {
1063     bar::<u32>($0);
1064 }
1065
1066 fn bar<T>(t: T) {}
1067 "#,
1068             expect![[r#"ty: u32, name: t"#]],
1069         );
1070     }
1071
1072     #[test]
1073     fn expected_type_generic_method() {
1074         check_expected_type_and_name(
1075             r#"
1076 fn foo() {
1077     S(1u32).bar($0);
1078 }
1079
1080 struct S<T>(T);
1081 impl<T> S<T> {
1082     fn bar(self, t: T) {}
1083 }
1084 "#,
1085             expect![[r#"ty: u32, name: t"#]],
1086         );
1087     }
1088 }