]> git.lizzy.rs Git - rust.git/blob - crates/ide_completion/src/context.rs
Merge #9706
[rust.git] / 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     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
382         let attrs = item.attrs(self.db);
383         let krate = item.krate(self.db);
384         match (attrs, krate) {
385             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
386             _ => false,
387         }
388     }
389
390     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
391     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
392         self.scope.process_all_names(&mut |name, def| {
393             if self.is_scope_def_hidden(&def) {
394                 return;
395             }
396
397             f(name, def);
398         })
399     }
400
401     fn is_visible_impl(
402         &self,
403         vis: &hir::Visibility,
404         attrs: &hir::Attrs,
405         defining_crate: hir::Crate,
406     ) -> bool {
407         let module = match self.scope.module() {
408             Some(it) => it,
409             None => return false,
410         };
411         if !vis.is_visible_from(self.db, module.into()) {
412             // If the definition location is editable, also show private items
413             let root_file = defining_crate.root_file(self.db);
414             let source_root_id = self.db.file_source_root(root_file);
415             let is_editable = !self.db.source_root(source_root_id).is_library;
416             return is_editable;
417         }
418
419         !self.is_doc_hidden(attrs, defining_crate)
420     }
421
422     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
423         let module = match self.scope.module() {
424             Some(it) => it,
425             None => return true,
426         };
427         if module.krate() != defining_crate && attrs.has_doc_hidden() {
428             // `doc(hidden)` items are only completed within the defining crate.
429             return true;
430         }
431
432         false
433     }
434
435     fn fill_impl_def(&mut self) {
436         self.impl_def = self
437             .sema
438             .token_ancestors_with_macros(self.token.clone())
439             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
440             .find_map(ast::Impl::cast);
441     }
442
443     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
444         let mut node = match self.token.parent() {
445             Some(it) => it,
446             None => return (None, None),
447         };
448         loop {
449             break match_ast! {
450                 match node {
451                     ast::LetStmt(it) => {
452                         cov_mark::hit!(expected_type_let_with_leading_char);
453                         cov_mark::hit!(expected_type_let_without_leading_char);
454                         let ty = it.pat()
455                             .and_then(|pat| self.sema.type_of_pat(&pat))
456                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)));
457                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
458                             ident.name().map(NameOrNameRef::Name)
459                         } else {
460                             None
461                         };
462
463                         (ty, name)
464                     },
465                     ast::ArgList(_it) => {
466                         cov_mark::hit!(expected_type_fn_param);
467                         ActiveParameter::at_token(
468                             &self.sema,
469                             self.token.clone(),
470                         ).map(|ap| {
471                             let name = ap.ident().map(NameOrNameRef::Name);
472                             let ty = if has_ref(&self.token) {
473                                 cov_mark::hit!(expected_type_fn_param_ref);
474                                 ap.ty.remove_ref()
475                             } else {
476                                 Some(ap.ty)
477                             };
478                             (ty, name)
479                         })
480                         .unwrap_or((None, None))
481                     },
482                     ast::RecordExprFieldList(_it) => {
483                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
484                         // wouldn't try {} be nice...
485                         (|| {
486                             let expr_field = self.token.prev_sibling_or_token()?
487                                       .into_node()
488                                       .and_then(ast::RecordExprField::cast)?;
489                             let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
490                             Some((
491                                 Some(ty),
492                                 expr_field.field_name().map(NameOrNameRef::NameRef),
493                             ))
494                         })().unwrap_or((None, None))
495                     },
496                     ast::RecordExprField(it) => {
497                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
498                         (
499                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)),
500                             it.field_name().map(NameOrNameRef::NameRef),
501                         )
502                     },
503                     ast::MatchExpr(it) => {
504                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
505                         let ty = it.expr()
506                             .and_then(|e| self.sema.type_of_expr(&e));
507                         (ty, None)
508                     },
509                     ast::IfExpr(it) => {
510                         cov_mark::hit!(expected_type_if_let_without_leading_char);
511                         let ty = it.condition()
512                             .and_then(|cond| cond.expr())
513                             .and_then(|e| self.sema.type_of_expr(&e));
514                         (ty, None)
515                     },
516                     ast::IdentPat(it) => {
517                         cov_mark::hit!(expected_type_if_let_with_leading_char);
518                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
519                         let ty = self.sema.type_of_pat(&ast::Pat::from(it));
520                         (ty, None)
521                     },
522                     ast::Fn(it) => {
523                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
524                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
525                         let def = self.sema.to_def(&it);
526                         (def.map(|def| def.ret_type(self.db)), None)
527                     },
528                     ast::ClosureExpr(it) => {
529                         let ty = self.sema.type_of_expr(&it.into());
530                         ty.and_then(|ty| ty.as_callable(self.db))
531                             .map(|c| (Some(c.return_type()), None))
532                             .unwrap_or((None, None))
533                     },
534                     ast::Stmt(_it) => (None, None),
535                     _ => {
536                         match node.parent() {
537                             Some(n) => {
538                                 node = n;
539                                 continue;
540                             },
541                             None => (None, None),
542                         }
543                     },
544                 }
545             };
546         }
547     }
548
549     fn fill(
550         &mut self,
551         original_file: &SyntaxNode,
552         file_with_fake_ident: SyntaxNode,
553         offset: TextSize,
554     ) {
555         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
556         let syntax_element = NodeOrToken::Token(fake_ident_token);
557         self.previous_token = previous_token(syntax_element.clone());
558         self.attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
559         self.no_completion_required = {
560             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
561             let fn_is_prev = self.previous_token_is(T![fn]);
562             let for_is_prev2 = for_is_prev2(syntax_element.clone());
563             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
564         };
565
566         self.incomplete_let =
567             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
568                 it.syntax().text_range().end() == syntax_element.text_range().end()
569             });
570
571         let (expected_type, expected_name) = self.expected_type_and_name();
572         self.expected_type = expected_type;
573         self.expected_name = expected_name;
574
575         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
576             Some(it) => it,
577             None => return,
578         };
579         self.completion_location =
580             determine_location(&self.sema, original_file, offset, &name_like);
581         self.prev_sibling = determine_prev_sibling(&name_like);
582         match name_like {
583             ast::NameLike::Lifetime(lifetime) => {
584                 self.classify_lifetime(original_file, lifetime, offset);
585             }
586             ast::NameLike::NameRef(name_ref) => {
587                 self.classify_name_ref(original_file, name_ref);
588             }
589             ast::NameLike::Name(name) => {
590                 self.classify_name(name);
591             }
592         }
593     }
594
595     fn classify_lifetime(
596         &mut self,
597         original_file: &SyntaxNode,
598         lifetime: ast::Lifetime,
599         offset: TextSize,
600     ) {
601         self.lifetime_syntax =
602             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
603         if let Some(parent) = lifetime.syntax().parent() {
604             if parent.kind() == ERROR {
605                 return;
606             }
607
608             match_ast! {
609                 match parent {
610                     ast::LifetimeParam(_it) => {
611                         self.lifetime_allowed = true;
612                         self.lifetime_param_syntax =
613                             self.sema.find_node_at_offset_with_macros(original_file, offset);
614                     },
615                     ast::BreakExpr(_it) => self.is_label_ref = true,
616                     ast::ContinueExpr(_it) => self.is_label_ref = true,
617                     ast::Label(_it) => (),
618                     _ => self.lifetime_allowed = true,
619                 }
620             }
621         }
622     }
623
624     fn classify_name(&mut self, name: ast::Name) {
625         if let Some(bind_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
626             self.is_pat_or_const = Some(PatternRefutability::Refutable);
627             // if any of these is here our bind pat can't be a const pat anymore
628             let complex_ident_pat = bind_pat.at_token().is_some()
629                 || bind_pat.ref_token().is_some()
630                 || bind_pat.mut_token().is_some();
631             if complex_ident_pat {
632                 self.is_pat_or_const = None;
633             } else {
634                 let irrefutable_pat = bind_pat.syntax().ancestors().find_map(|node| {
635                     match_ast! {
636                         match node {
637                             ast::LetStmt(it) => Some(it.pat()),
638                             ast::Param(it) => Some(it.pat()),
639                             _ => None,
640                         }
641                     }
642                 });
643                 if let Some(Some(pat)) = irrefutable_pat {
644                     // This check is here since we could be inside a pattern in the initializer expression of the let statement.
645                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
646                         self.is_pat_or_const = Some(PatternRefutability::Irrefutable);
647                     }
648                 }
649
650                 let is_name_in_field_pat = bind_pat
651                     .syntax()
652                     .parent()
653                     .and_then(ast::RecordPatField::cast)
654                     .map_or(false, |pat_field| pat_field.name_ref().is_none());
655                 if is_name_in_field_pat {
656                     self.is_pat_or_const = None;
657                 }
658             }
659
660             self.fill_impl_def();
661         }
662
663         self.is_param |= is_node::<ast::Param>(name.syntax());
664     }
665
666     fn classify_name_ref(&mut self, original_file: &SyntaxNode, name_ref: ast::NameRef) {
667         self.fill_impl_def();
668
669         self.name_ref_syntax =
670             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
671
672         self.function_def = self
673             .sema
674             .token_ancestors_with_macros(self.token.clone())
675             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
676             .find_map(ast::Fn::cast);
677
678         let parent = match name_ref.syntax().parent() {
679             Some(it) => it,
680             None => return,
681         };
682
683         if let Some(segment) = ast::PathSegment::cast(parent) {
684             let path_ctx = self.path_context.get_or_insert(PathCompletionContext {
685                 call_kind: None,
686                 is_trivial_path: false,
687                 qualifier: None,
688                 has_type_args: false,
689                 can_be_stmt: false,
690                 in_loop_body: false,
691                 use_tree_parent: false,
692                 kind: None,
693             });
694             path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
695             let path = segment.parent_path();
696
697             if let Some(p) = path.syntax().parent() {
698                 path_ctx.call_kind = match_ast! {
699                     match p {
700                         ast::PathExpr(it) => it.syntax().parent().and_then(ast::CallExpr::cast).map(|_| CallKind::Expr),
701                         ast::MacroCall(it) => it.excl_token().and(Some(CallKind::Mac)),
702                         ast::TupleStructPat(_it) => Some(CallKind::Pat),
703                         _ => None
704                     }
705                 };
706             }
707
708             if let Some(parent) = path.syntax().parent() {
709                 path_ctx.kind = match_ast! {
710                     match parent {
711                         ast::PathType(_it) => Some(PathKind::Type),
712                         ast::PathExpr(_it) => Some(PathKind::Expr),
713                         _ => None,
714                     }
715                 };
716             }
717             path_ctx.has_type_args = segment.generic_arg_list().is_some();
718
719             if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
720                 path_ctx.use_tree_parent = use_tree_parent;
721                 path_ctx.qualifier = path
722                     .segment()
723                     .and_then(|it| {
724                         find_node_with_range::<ast::PathSegment>(
725                             original_file,
726                             it.syntax().text_range(),
727                         )
728                     })
729                     .map(|it| it.parent_path());
730                 return;
731             }
732
733             if let Some(segment) = path.segment() {
734                 if segment.coloncolon_token().is_some() {
735                     return;
736                 }
737             }
738
739             path_ctx.is_trivial_path = true;
740
741             // Find either enclosing expr statement (thing with `;`) or a
742             // block. If block, check that we are the last expr.
743             path_ctx.can_be_stmt = name_ref
744                 .syntax()
745                 .ancestors()
746                 .find_map(|node| {
747                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
748                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
749                     }
750                     if let Some(block) = ast::BlockExpr::cast(node) {
751                         return Some(
752                             block.tail_expr().map(|e| e.syntax().text_range())
753                                 == Some(name_ref.syntax().text_range()),
754                         );
755                     }
756                     None
757                 })
758                 .unwrap_or(false);
759         }
760     }
761 }
762
763 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
764     syntax.covering_element(range).ancestors().find_map(N::cast)
765 }
766
767 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
768     match node.ancestors().find_map(N::cast) {
769         None => false,
770         Some(n) => n.syntax().text_range() == node.text_range(),
771     }
772 }
773
774 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
775     if let Some(qual) = path.qualifier() {
776         return Some((qual, false));
777     }
778     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
779     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
780     use_tree.path().zip(Some(true))
781 }
782
783 fn has_ref(token: &SyntaxToken) -> bool {
784     let mut token = token.clone();
785     for skip in [WHITESPACE, IDENT, T![mut]] {
786         if token.kind() == skip {
787             token = match token.prev_token() {
788                 Some(it) => it,
789                 None => return false,
790             }
791         }
792     }
793     token.kind() == T![&]
794 }
795
796 #[cfg(test)]
797 mod tests {
798     use expect_test::{expect, Expect};
799     use hir::HirDisplay;
800
801     use crate::tests::{position, TEST_CONFIG};
802
803     use super::CompletionContext;
804
805     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
806         let (db, pos) = position(ra_fixture);
807         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
808
809         let ty = completion_context
810             .expected_type
811             .map(|t| t.display_test(&db).to_string())
812             .unwrap_or("?".to_owned());
813
814         let name = completion_context
815             .expected_name
816             .map_or_else(|| "?".to_owned(), |name| name.to_string());
817
818         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
819     }
820
821     #[test]
822     fn expected_type_let_without_leading_char() {
823         cov_mark::check!(expected_type_let_without_leading_char);
824         check_expected_type_and_name(
825             r#"
826 fn foo() {
827     let x: u32 = $0;
828 }
829 "#,
830             expect![[r#"ty: u32, name: x"#]],
831         );
832     }
833
834     #[test]
835     fn expected_type_let_with_leading_char() {
836         cov_mark::check!(expected_type_let_with_leading_char);
837         check_expected_type_and_name(
838             r#"
839 fn foo() {
840     let x: u32 = c$0;
841 }
842 "#,
843             expect![[r#"ty: u32, name: x"#]],
844         );
845     }
846
847     #[test]
848     fn expected_type_let_pat() {
849         check_expected_type_and_name(
850             r#"
851 fn foo() {
852     let x$0 = 0u32;
853 }
854 "#,
855             expect![[r#"ty: u32, name: ?"#]],
856         );
857         check_expected_type_and_name(
858             r#"
859 fn foo() {
860     let $0 = 0u32;
861 }
862 "#,
863             expect![[r#"ty: u32, name: ?"#]],
864         );
865     }
866
867     #[test]
868     fn expected_type_fn_param() {
869         cov_mark::check!(expected_type_fn_param);
870         check_expected_type_and_name(
871             r#"
872 fn foo() { bar($0); }
873 fn bar(x: u32) {}
874 "#,
875             expect![[r#"ty: u32, name: x"#]],
876         );
877         check_expected_type_and_name(
878             r#"
879 fn foo() { bar(c$0); }
880 fn bar(x: u32) {}
881 "#,
882             expect![[r#"ty: u32, name: x"#]],
883         );
884     }
885
886     #[test]
887     fn expected_type_fn_param_ref() {
888         cov_mark::check!(expected_type_fn_param_ref);
889         check_expected_type_and_name(
890             r#"
891 fn foo() { bar(&$0); }
892 fn bar(x: &u32) {}
893 "#,
894             expect![[r#"ty: u32, name: x"#]],
895         );
896         check_expected_type_and_name(
897             r#"
898 fn foo() { bar(&mut $0); }
899 fn bar(x: &mut u32) {}
900 "#,
901             expect![[r#"ty: u32, name: x"#]],
902         );
903         check_expected_type_and_name(
904             r#"
905 fn foo() { bar(&c$0); }
906 fn bar(x: &u32) {}
907         "#,
908             expect![[r#"ty: u32, name: x"#]],
909         );
910     }
911
912     #[test]
913     fn expected_type_struct_field_without_leading_char() {
914         cov_mark::check!(expected_type_struct_field_without_leading_char);
915         check_expected_type_and_name(
916             r#"
917 struct Foo { a: u32 }
918 fn foo() {
919     Foo { a: $0 };
920 }
921 "#,
922             expect![[r#"ty: u32, name: a"#]],
923         )
924     }
925
926     #[test]
927     fn expected_type_generic_struct_field() {
928         check_expected_type_and_name(
929             r#"
930 struct Foo<T> { a: T }
931 fn foo() -> Foo<u32> {
932     Foo { a: $0 }
933 }
934 "#,
935             expect![[r#"ty: u32, name: a"#]],
936         )
937     }
938
939     #[test]
940     fn expected_type_struct_field_with_leading_char() {
941         cov_mark::check!(expected_type_struct_field_with_leading_char);
942         check_expected_type_and_name(
943             r#"
944 struct Foo { a: u32 }
945 fn foo() {
946     Foo { a: c$0 };
947 }
948 "#,
949             expect![[r#"ty: u32, name: a"#]],
950         );
951     }
952
953     #[test]
954     fn expected_type_match_arm_without_leading_char() {
955         cov_mark::check!(expected_type_match_arm_without_leading_char);
956         check_expected_type_and_name(
957             r#"
958 enum E { X }
959 fn foo() {
960    match E::X { $0 }
961 }
962 "#,
963             expect![[r#"ty: E, name: ?"#]],
964         );
965     }
966
967     #[test]
968     fn expected_type_match_arm_with_leading_char() {
969         cov_mark::check!(expected_type_match_arm_with_leading_char);
970         check_expected_type_and_name(
971             r#"
972 enum E { X }
973 fn foo() {
974    match E::X { c$0 }
975 }
976 "#,
977             expect![[r#"ty: E, name: ?"#]],
978         );
979     }
980
981     #[test]
982     fn expected_type_if_let_without_leading_char() {
983         cov_mark::check!(expected_type_if_let_without_leading_char);
984         check_expected_type_and_name(
985             r#"
986 enum Foo { Bar, Baz, Quux }
987
988 fn foo() {
989     let f = Foo::Quux;
990     if let $0 = f { }
991 }
992 "#,
993             expect![[r#"ty: Foo, name: ?"#]],
994         )
995     }
996
997     #[test]
998     fn expected_type_if_let_with_leading_char() {
999         cov_mark::check!(expected_type_if_let_with_leading_char);
1000         check_expected_type_and_name(
1001             r#"
1002 enum Foo { Bar, Baz, Quux }
1003
1004 fn foo() {
1005     let f = Foo::Quux;
1006     if let c$0 = f { }
1007 }
1008 "#,
1009             expect![[r#"ty: Foo, name: ?"#]],
1010         )
1011     }
1012
1013     #[test]
1014     fn expected_type_fn_ret_without_leading_char() {
1015         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1016         check_expected_type_and_name(
1017             r#"
1018 fn foo() -> u32 {
1019     $0
1020 }
1021 "#,
1022             expect![[r#"ty: u32, name: ?"#]],
1023         )
1024     }
1025
1026     #[test]
1027     fn expected_type_fn_ret_with_leading_char() {
1028         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1029         check_expected_type_and_name(
1030             r#"
1031 fn foo() -> u32 {
1032     c$0
1033 }
1034 "#,
1035             expect![[r#"ty: u32, name: ?"#]],
1036         )
1037     }
1038
1039     #[test]
1040     fn expected_type_fn_ret_fn_ref_fully_typed() {
1041         check_expected_type_and_name(
1042             r#"
1043 fn foo() -> u32 {
1044     foo$0
1045 }
1046 "#,
1047             expect![[r#"ty: u32, name: ?"#]],
1048         )
1049     }
1050
1051     #[test]
1052     fn expected_type_closure_param_return() {
1053         // FIXME: make this work with `|| $0`
1054         check_expected_type_and_name(
1055             r#"
1056 //- minicore: fn
1057 fn foo() {
1058     bar(|| a$0);
1059 }
1060
1061 fn bar(f: impl FnOnce() -> u32) {}
1062 "#,
1063             expect![[r#"ty: u32, name: ?"#]],
1064         );
1065     }
1066
1067     #[test]
1068     fn expected_type_generic_function() {
1069         check_expected_type_and_name(
1070             r#"
1071 fn foo() {
1072     bar::<u32>($0);
1073 }
1074
1075 fn bar<T>(t: T) {}
1076 "#,
1077             expect![[r#"ty: u32, name: t"#]],
1078         );
1079     }
1080
1081     #[test]
1082     fn expected_type_generic_method() {
1083         check_expected_type_and_name(
1084             r#"
1085 fn foo() {
1086     S(1u32).bar($0);
1087 }
1088
1089 struct S<T>(T);
1090 impl<T> S<T> {
1091     fn bar(self, t: T) {}
1092 }
1093 "#,
1094             expect![[r#"ty: u32, name: t"#]],
1095         );
1096     }
1097 }