src/tools/clippy/clippy_lints/src/entry.rs

   1 use clippy_utils::higher;
   2 use clippy_utils::{
   3     can_move_expr_to_closure_no_visit,
   4     diagnostics::span_lint_and_sugg,
   5     is_expr_final_block_expr, is_expr_used_or_unified, match_def_path, paths, peel_hir_expr_while,
   6     source::{reindent_multiline, snippet_indent, snippet_with_applicability, snippet_with_context},
   7     SpanlessEq,
   8 };
   9 use core::fmt::Write;
  10 use rustc_errors::Applicability;
  11 use rustc_hir::{
  12     hir_id::HirIdSet,
  13     intravisit::{walk_expr, Visitor},
  14     Block, Expr, ExprKind, Guard, HirId, Let, Pat, Stmt, StmtKind, UnOp,
  15 };
  16 use rustc_lint::{LateContext, LateLintPass};
  17 use rustc_session::{declare_lint_pass, declare_tool_lint};
  18 use rustc_span::{Span, SyntaxContext, DUMMY_SP};
  19
  20 declare_clippy_lint! {
  21     /// ### What it does
  22     /// Checks for uses of `contains_key` + `insert` on `HashMap`
  23     /// or `BTreeMap`.
  24     ///
  25     /// ### Why is this bad?
  26     /// Using `entry` is more efficient.
  27     ///
  28     /// ### Known problems
  29     /// The suggestion may have type inference errors in some cases. e.g.
  30     /// ```rust
  31     /// let mut map = std::collections::HashMap::new();
  32     /// let _ = if !map.contains_key(&0) {
  33     ///     map.insert(0, 0)
  34     /// } else {
  35     ///     None
  36     /// };
  37     /// ```
  38     ///
  39     /// ### Example
  40     /// ```rust
  41     /// # use std::collections::HashMap;
  42     /// # let mut map = HashMap::new();
  43     /// # let k = 1;
  44     /// # let v = 1;
  45     /// if !map.contains_key(&k) {
  46     ///     map.insert(k, v);
  47     /// }
  48     /// ```
  49     /// Use instead:
  50     /// ```rust
  51     /// # use std::collections::HashMap;
  52     /// # let mut map = HashMap::new();
  53     /// # let k = 1;
  54     /// # let v = 1;
  55     /// map.entry(k).or_insert(v);
  56     /// ```
  57     #[clippy::version = "pre 1.29.0"]
  58     pub MAP_ENTRY,
  59     perf,
  60     "use of `contains_key` followed by `insert` on a `HashMap` or `BTreeMap`"
  61 }
  62
  63 declare_lint_pass!(HashMapPass => [MAP_ENTRY]);
  64
  65 impl<'tcx> LateLintPass<'tcx> for HashMapPass {
  66     #[expect(clippy::too_many_lines)]
  67     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
  68         let Some(higher::If { cond: cond_expr, then: then_expr, r#else: else_expr }) = higher::If::hir(expr) else {
  69             return
  70         };
  71
  72         let Some((map_ty, contains_expr)) = try_parse_contains(cx, cond_expr) else {
  73             return
  74         };
  75
  76         let Some(then_search) = find_insert_calls(cx, &contains_expr, then_expr) else {
  77             return
  78         };
  79
  80         let mut app = Applicability::MachineApplicable;
  81         let map_str = snippet_with_context(cx, contains_expr.map.span, contains_expr.call_ctxt, "..", &mut app).0;
  82         let key_str = snippet_with_context(cx, contains_expr.key.span, contains_expr.call_ctxt, "..", &mut app).0;
  83         let sugg = if let Some(else_expr) = else_expr {
  84             let Some(else_search) = find_insert_calls(cx, &contains_expr, else_expr) else {
  85                 return;
  86             };
  87
  88             if then_search.edits.is_empty() && else_search.edits.is_empty() {
  89                 // No insertions
  90                 return;
  91             } else if then_search.edits.is_empty() || else_search.edits.is_empty() {
  92                 // if .. { insert } else { .. } or if .. { .. } else { insert }
  93                 let ((then_str, entry_kind), else_str) = match (else_search.edits.is_empty(), contains_expr.negated) {
  94                     (true, true) => (
  95                         then_search.snippet_vacant(cx, then_expr.span, &mut app),
  96                         snippet_with_applicability(cx, else_expr.span, "{ .. }", &mut app),
  97                     ),
  98                     (true, false) => (
  99                         then_search.snippet_occupied(cx, then_expr.span, &mut app),
 100                         snippet_with_applicability(cx, else_expr.span, "{ .. }", &mut app),
 101                     ),
 102                     (false, true) => (
 103                         else_search.snippet_occupied(cx, else_expr.span, &mut app),
 104                         snippet_with_applicability(cx, then_expr.span, "{ .. }", &mut app),
 105                     ),
 106                     (false, false) => (
 107                         else_search.snippet_vacant(cx, else_expr.span, &mut app),
 108                         snippet_with_applicability(cx, then_expr.span, "{ .. }", &mut app),
 109                     ),
 110                 };
 111                 format!(
 112                     "if let {}::{entry_kind} = {map_str}.entry({key_str}) {then_str} else {else_str}",
 113                     map_ty.entry_path(),
 114                 )
 115             } else {
 116                 // if .. { insert } else { insert }
 117                 let ((then_str, then_entry), (else_str, else_entry)) = if contains_expr.negated {
 118                     (
 119                         then_search.snippet_vacant(cx, then_expr.span, &mut app),
 120                         else_search.snippet_occupied(cx, else_expr.span, &mut app),
 121                     )
 122                 } else {
 123                     (
 124                         then_search.snippet_occupied(cx, then_expr.span, &mut app),
 125                         else_search.snippet_vacant(cx, else_expr.span, &mut app),
 126                     )
 127                 };
 128                 let indent_str = snippet_indent(cx, expr.span);
 129                 let indent_str = indent_str.as_deref().unwrap_or("");
 130                 format!(
 131                     "match {map_str}.entry({key_str}) {{\n{indent_str}    {entry}::{then_entry} => {}\n\
 132                         {indent_str}    {entry}::{else_entry} => {}\n{indent_str}}}",
 133                     reindent_multiline(then_str.into(), true, Some(4 + indent_str.len())),
 134                     reindent_multiline(else_str.into(), true, Some(4 + indent_str.len())),
 135                     entry = map_ty.entry_path(),
 136                 )
 137             }
 138         } else {
 139             if then_search.edits.is_empty() {
 140                 // no insertions
 141                 return;
 142             }
 143
 144             // if .. { insert }
 145             if !then_search.allow_insert_closure {
 146                 let (body_str, entry_kind) = if contains_expr.negated {
 147                     then_search.snippet_vacant(cx, then_expr.span, &mut app)
 148                 } else {
 149                     then_search.snippet_occupied(cx, then_expr.span, &mut app)
 150                 };
 151                 format!(
 152                     "if let {}::{entry_kind} = {map_str}.entry({key_str}) {body_str}",
 153                     map_ty.entry_path(),
 154                 )
 155             } else if let Some(insertion) = then_search.as_single_insertion() {
 156                 let value_str = snippet_with_context(cx, insertion.value.span, then_expr.span.ctxt(), "..", &mut app).0;
 157                 if contains_expr.negated {
 158                     if insertion.value.can_have_side_effects() {
 159                         format!("{map_str}.entry({key_str}).or_insert_with(|| {value_str});")
 160                     } else {
 161                         format!("{map_str}.entry({key_str}).or_insert({value_str});")
 162                     }
 163                 } else {
 164                     // TODO: suggest using `if let Some(v) = map.get_mut(k) { .. }` here.
 165                     // This would need to be a different lint.
 166                     return;
 167                 }
 168             } else {
 169                 let block_str = then_search.snippet_closure(cx, then_expr.span, &mut app);
 170                 if contains_expr.negated {
 171                     format!("{map_str}.entry({key_str}).or_insert_with(|| {block_str});")
 172                 } else {
 173                     // TODO: suggest using `if let Some(v) = map.get_mut(k) { .. }` here.
 174                     // This would need to be a different lint.
 175                     return;
 176                 }
 177             }
 178         };
 179
 180         span_lint_and_sugg(
 181             cx,
 182             MAP_ENTRY,
 183             expr.span,
 184             &format!("usage of `contains_key` followed by `insert` on a `{}`", map_ty.name()),
 185             "try this",
 186             sugg,
 187             app,
 188         );
 189     }
 190 }
 191
 192 #[derive(Clone, Copy)]
 193 enum MapType {
 194     Hash,
 195     BTree,
 196 }
 197 impl MapType {
 198     fn name(self) -> &'static str {
 199         match self {
 200             Self::Hash => "HashMap",
 201             Self::BTree => "BTreeMap",
 202         }
 203     }
 204     fn entry_path(self) -> &'static str {
 205         match self {
 206             Self::Hash => "std::collections::hash_map::Entry",
 207             Self::BTree => "std::collections::btree_map::Entry",
 208         }
 209     }
 210 }
 211
 212 struct ContainsExpr<'tcx> {
 213     negated: bool,
 214     map: &'tcx Expr<'tcx>,
 215     key: &'tcx Expr<'tcx>,
 216     call_ctxt: SyntaxContext,
 217 }
 218 fn try_parse_contains<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<(MapType, ContainsExpr<'tcx>)> {
 219     let mut negated = false;
 220     let expr = peel_hir_expr_while(expr, |e| match e.kind {
 221         ExprKind::Unary(UnOp::Not, e) => {
 222             negated = !negated;
 223             Some(e)
 224         },
 225         _ => None,
 226     });
 227     match expr.kind {
 228         ExprKind::MethodCall(
 229             _,
 230             map,
 231             [
 232                 Expr {
 233                     kind: ExprKind::AddrOf(_, _, key),
 234                     span: key_span,
 235                     ..
 236                 },
 237             ],
 238             _,
 239         ) if key_span.ctxt() == expr.span.ctxt() => {
 240             let id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
 241             let expr = ContainsExpr {
 242                 negated,
 243                 map,
 244                 key,
 245                 call_ctxt: expr.span.ctxt(),
 246             };
 247             if match_def_path(cx, id, &paths::BTREEMAP_CONTAINS_KEY) {
 248                 Some((MapType::BTree, expr))
 249             } else if match_def_path(cx, id, &paths::HASHMAP_CONTAINS_KEY) {
 250                 Some((MapType::Hash, expr))
 251             } else {
 252                 None
 253             }
 254         },
 255         _ => None,
 256     }
 257 }
 258
 259 struct InsertExpr<'tcx> {
 260     map: &'tcx Expr<'tcx>,
 261     key: &'tcx Expr<'tcx>,
 262     value: &'tcx Expr<'tcx>,
 263 }
 264 fn try_parse_insert<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<InsertExpr<'tcx>> {
 265     if let ExprKind::MethodCall(_, map, [key, value], _) = expr.kind {
 266         let id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
 267         if match_def_path(cx, id, &paths::BTREEMAP_INSERT) || match_def_path(cx, id, &paths::HASHMAP_INSERT) {
 268             Some(InsertExpr { map, key, value })
 269         } else {
 270             None
 271         }
 272     } else {
 273         None
 274     }
 275 }
 276
 277 /// An edit that will need to be made to move the expression to use the entry api
 278 #[derive(Clone, Copy)]
 279 enum Edit<'tcx> {
 280     /// A semicolon that needs to be removed. Used to create a closure for `insert_with`.
 281     RemoveSemi(Span),
 282     /// An insertion into the map.
 283     Insertion(Insertion<'tcx>),
 284 }
 285 impl<'tcx> Edit<'tcx> {
 286     fn as_insertion(self) -> Option<Insertion<'tcx>> {
 287         if let Self::Insertion(i) = self { Some(i) } else { None }
 288     }
 289 }
 290 #[derive(Clone, Copy)]
 291 struct Insertion<'tcx> {
 292     call: &'tcx Expr<'tcx>,
 293     value: &'tcx Expr<'tcx>,
 294 }
 295
 296 /// This visitor needs to do a multiple things:
 297 /// * Find all usages of the map. An insertion can only be made before any other usages of the map.
 298 /// * Determine if there's an insertion using the same key. There's no need for the entry api
 299 ///   otherwise.
 300 /// * Determine if the final statement executed is an insertion. This is needed to use
 301 ///   `or_insert_with`.
 302 /// * Determine if there's any sub-expression that can't be placed in a closure.
 303 /// * Determine if there's only a single insert statement. `or_insert` can be used in this case.
 304 #[expect(clippy::struct_excessive_bools)]
 305 struct InsertSearcher<'cx, 'tcx> {
 306     cx: &'cx LateContext<'tcx>,
 307     /// The map expression used in the contains call.
 308     map: &'tcx Expr<'tcx>,
 309     /// The key expression used in the contains call.
 310     key: &'tcx Expr<'tcx>,
 311     /// The context of the top level block. All insert calls must be in the same context.
 312     ctxt: SyntaxContext,
 313     /// Whether this expression can be safely moved into a closure.
 314     allow_insert_closure: bool,
 315     /// Whether this expression can use the entry api.
 316     can_use_entry: bool,
 317     /// Whether this expression is the final expression in this code path. This may be a statement.
 318     in_tail_pos: bool,
 319     // Is this expression a single insert. A slightly better suggestion can be made in this case.
 320     is_single_insert: bool,
 321     /// If the visitor has seen the map being used.
 322     is_map_used: bool,
 323     /// The locations where changes need to be made for the suggestion.
 324     edits: Vec<Edit<'tcx>>,
 325     /// A stack of loops the visitor is currently in.
 326     loops: Vec<HirId>,
 327     /// Local variables created in the expression. These don't need to be captured.
 328     locals: HirIdSet,
 329 }
 330 impl<'tcx> InsertSearcher<'_, 'tcx> {
 331     /// Visit the expression as a branch in control flow. Multiple insert calls can be used, but
 332     /// only if they are on separate code paths. This will return whether the map was used in the
 333     /// given expression.
 334     fn visit_cond_arm(&mut self, e: &'tcx Expr<'_>) -> bool {
 335         let is_map_used = self.is_map_used;
 336         let in_tail_pos = self.in_tail_pos;
 337         self.visit_expr(e);
 338         let res = self.is_map_used;
 339         self.is_map_used = is_map_used;
 340         self.in_tail_pos = in_tail_pos;
 341         res
 342     }
 343
 344     /// Visits an expression which is not itself in a tail position, but other sibling expressions
 345     /// may be. e.g. if conditions
 346     fn visit_non_tail_expr(&mut self, e: &'tcx Expr<'_>) {
 347         let in_tail_pos = self.in_tail_pos;
 348         self.in_tail_pos = false;
 349         self.visit_expr(e);
 350         self.in_tail_pos = in_tail_pos;
 351     }
 352 }
 353 impl<'tcx> Visitor<'tcx> for InsertSearcher<'_, 'tcx> {
 354     fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) {
 355         match stmt.kind {
 356             StmtKind::Semi(e) => {
 357                 self.visit_expr(e);
 358
 359                 if self.in_tail_pos && self.allow_insert_closure {
 360                     // The spans are used to slice the top level expression into multiple parts. This requires that
 361                     // they all come from the same part of the source code.
 362                     if stmt.span.ctxt() == self.ctxt && e.span.ctxt() == self.ctxt {
 363                         self.edits
 364                             .push(Edit::RemoveSemi(stmt.span.trim_start(e.span).unwrap_or(DUMMY_SP)));
 365                     } else {
 366                         self.allow_insert_closure = false;
 367                     }
 368                 }
 369             },
 370             StmtKind::Expr(e) => self.visit_expr(e),
 371             StmtKind::Local(l) => {
 372                 self.visit_pat(l.pat);
 373                 if let Some(e) = l.init {
 374                     self.allow_insert_closure &= !self.in_tail_pos;
 375                     self.in_tail_pos = false;
 376                     self.is_single_insert = false;
 377                     self.visit_expr(e);
 378                 }
 379             },
 380             StmtKind::Item(_) => {
 381                 self.allow_insert_closure &= !self.in_tail_pos;
 382                 self.is_single_insert = false;
 383             },
 384         }
 385     }
 386
 387     fn visit_block(&mut self, block: &'tcx Block<'_>) {
 388         // If the block is in a tail position, then the last expression (possibly a statement) is in the
 389         // tail position. The rest, however, are not.
 390         match (block.stmts, block.expr) {
 391             ([], None) => {
 392                 self.allow_insert_closure &= !self.in_tail_pos;
 393             },
 394             ([], Some(expr)) => self.visit_expr(expr),
 395             (stmts, Some(expr)) => {
 396                 let in_tail_pos = self.in_tail_pos;
 397                 self.in_tail_pos = false;
 398                 for stmt in stmts {
 399                     self.visit_stmt(stmt);
 400                 }
 401                 self.in_tail_pos = in_tail_pos;
 402                 self.visit_expr(expr);
 403             },
 404             ([stmts @ .., stmt], None) => {
 405                 let in_tail_pos = self.in_tail_pos;
 406                 self.in_tail_pos = false;
 407                 for stmt in stmts {
 408                     self.visit_stmt(stmt);
 409                 }
 410                 self.in_tail_pos = in_tail_pos;
 411                 self.visit_stmt(stmt);
 412             },
 413         }
 414     }
 415
 416     fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
 417         if !self.can_use_entry {
 418             return;
 419         }
 420
 421         match try_parse_insert(self.cx, expr) {
 422             Some(insert_expr) if SpanlessEq::new(self.cx).eq_expr(self.map, insert_expr.map) => {
 423                 // Multiple inserts, inserts with a different key, and inserts from a macro can't use the entry api.
 424                 if self.is_map_used
 425                     || !SpanlessEq::new(self.cx).eq_expr(self.key, insert_expr.key)
 426                     || expr.span.ctxt() != self.ctxt
 427                 {
 428                     self.can_use_entry = false;
 429                     return;
 430                 }
 431
 432                 self.edits.push(Edit::Insertion(Insertion {
 433                     call: expr,
 434                     value: insert_expr.value,
 435                 }));
 436                 self.is_map_used = true;
 437                 self.allow_insert_closure &= self.in_tail_pos;
 438
 439                 // The value doesn't affect whether there is only a single insert expression.
 440                 let is_single_insert = self.is_single_insert;
 441                 self.visit_non_tail_expr(insert_expr.value);
 442                 self.is_single_insert = is_single_insert;
 443             },
 444             _ if SpanlessEq::new(self.cx).eq_expr(self.map, expr) => {
 445                 self.is_map_used = true;
 446             },
 447             _ => match expr.kind {
 448                 ExprKind::If(cond_expr, then_expr, Some(else_expr)) => {
 449                     self.is_single_insert = false;
 450                     self.visit_non_tail_expr(cond_expr);
 451                     // Each branch may contain it's own insert expression.
 452                     let mut is_map_used = self.visit_cond_arm(then_expr);
 453                     is_map_used |= self.visit_cond_arm(else_expr);
 454                     self.is_map_used = is_map_used;
 455                 },
 456                 ExprKind::Match(scrutinee_expr, arms, _) => {
 457                     self.is_single_insert = false;
 458                     self.visit_non_tail_expr(scrutinee_expr);
 459                     // Each branch may contain it's own insert expression.
 460                     let mut is_map_used = self.is_map_used;
 461                     for arm in arms {
 462                         self.visit_pat(arm.pat);
 463                         if let Some(Guard::If(guard) | Guard::IfLet(&Let { init: guard, .. })) = arm.guard {
 464                             self.visit_non_tail_expr(guard);
 465                         }
 466                         is_map_used |= self.visit_cond_arm(arm.body);
 467                     }
 468                     self.is_map_used = is_map_used;
 469                 },
 470                 ExprKind::Loop(block, ..) => {
 471                     self.loops.push(expr.hir_id);
 472                     self.is_single_insert = false;
 473                     self.allow_insert_closure &= !self.in_tail_pos;
 474                     // Don't allow insertions inside of a loop.
 475                     let edit_len = self.edits.len();
 476                     self.visit_block(block);
 477                     if self.edits.len() != edit_len {
 478                         self.can_use_entry = false;
 479                     }
 480                     self.loops.pop();
 481                 },
 482                 ExprKind::Block(block, _) => self.visit_block(block),
 483                 ExprKind::InlineAsm(_) => {
 484                     self.can_use_entry = false;
 485                 },
 486                 _ => {
 487                     self.allow_insert_closure &= !self.in_tail_pos;
 488                     self.allow_insert_closure &=
 489                         can_move_expr_to_closure_no_visit(self.cx, expr, &self.loops, &self.locals);
 490                     // Sub expressions are no longer in the tail position.
 491                     self.is_single_insert = false;
 492                     self.in_tail_pos = false;
 493                     walk_expr(self, expr);
 494                 },
 495             },
 496         }
 497     }
 498
 499     fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
 500         p.each_binding_or_first(&mut |_, id, _, _| {
 501             self.locals.insert(id);
 502         });
 503     }
 504 }
 505
 506 struct InsertSearchResults<'tcx> {
 507     edits: Vec<Edit<'tcx>>,
 508     allow_insert_closure: bool,
 509     is_single_insert: bool,
 510 }
 511 impl<'tcx> InsertSearchResults<'tcx> {
 512     fn as_single_insertion(&self) -> Option<Insertion<'tcx>> {
 513         self.is_single_insert.then(|| self.edits[0].as_insertion().unwrap())
 514     }
 515
 516     fn snippet(
 517         &self,
 518         cx: &LateContext<'_>,
 519         mut span: Span,
 520         app: &mut Applicability,
 521         write_wrapped: impl Fn(&mut String, Insertion<'_>, SyntaxContext, &mut Applicability),
 522     ) -> String {
 523         let ctxt = span.ctxt();
 524         let mut res = String::new();
 525         for insertion in self.edits.iter().filter_map(|e| e.as_insertion()) {
 526             res.push_str(&snippet_with_applicability(
 527                 cx,
 528                 span.until(insertion.call.span),
 529                 "..",
 530                 app,
 531             ));
 532             if is_expr_used_or_unified(cx.tcx, insertion.call) {
 533                 write_wrapped(&mut res, insertion, ctxt, app);
 534             } else {
 535                 let _ = write!(
 536                     res,
 537                     "e.insert({})",
 538                     snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0
 539                 );
 540             }
 541             span = span.trim_start(insertion.call.span).unwrap_or(DUMMY_SP);
 542         }
 543         res.push_str(&snippet_with_applicability(cx, span, "..", app));
 544         res
 545     }
 546
 547     fn snippet_occupied(&self, cx: &LateContext<'_>, span: Span, app: &mut Applicability) -> (String, &'static str) {
 548         (
 549             self.snippet(cx, span, app, |res, insertion, ctxt, app| {
 550                 // Insertion into a map would return `Some(&mut value)`, but the entry returns `&mut value`
 551                 let _ = write!(
 552                     res,
 553                     "Some(e.insert({}))",
 554                     snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0
 555                 );
 556             }),
 557             "Occupied(mut e)",
 558         )
 559     }
 560
 561     fn snippet_vacant(&self, cx: &LateContext<'_>, span: Span, app: &mut Applicability) -> (String, &'static str) {
 562         (
 563             self.snippet(cx, span, app, |res, insertion, ctxt, app| {
 564                 // Insertion into a map would return `None`, but the entry returns a mutable reference.
 565                 let _ = if is_expr_final_block_expr(cx.tcx, insertion.call) {
 566                     write!(
 567                         res,
 568                         "e.insert({});\n{}None",
 569                         snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0,
 570                         snippet_indent(cx, insertion.call.span).as_deref().unwrap_or(""),
 571                     )
 572                 } else {
 573                     write!(
 574                         res,
 575                         "{{ e.insert({}); None }}",
 576                         snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0,
 577                     )
 578                 };
 579             }),
 580             "Vacant(e)",
 581         )
 582     }
 583
 584     fn snippet_closure(&self, cx: &LateContext<'_>, mut span: Span, app: &mut Applicability) -> String {
 585         let ctxt = span.ctxt();
 586         let mut res = String::new();
 587         for edit in &self.edits {
 588             match *edit {
 589                 Edit::Insertion(insertion) => {
 590                     // Cut out the value from `map.insert(key, value)`
 591                     res.push_str(&snippet_with_applicability(
 592                         cx,
 593                         span.until(insertion.call.span),
 594                         "..",
 595                         app,
 596                     ));
 597                     res.push_str(&snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0);
 598                     span = span.trim_start(insertion.call.span).unwrap_or(DUMMY_SP);
 599                 },
 600                 Edit::RemoveSemi(semi_span) => {
 601                     // Cut out the semicolon. This allows the value to be returned from the closure.
 602                     res.push_str(&snippet_with_applicability(cx, span.until(semi_span), "..", app));
 603                     span = span.trim_start(semi_span).unwrap_or(DUMMY_SP);
 604                 },
 605             }
 606         }
 607         res.push_str(&snippet_with_applicability(cx, span, "..", app));
 608         res
 609     }
 610 }
 611
 612 fn find_insert_calls<'tcx>(
 613     cx: &LateContext<'tcx>,
 614     contains_expr: &ContainsExpr<'tcx>,
 615     expr: &'tcx Expr<'_>,
 616 ) -> Option<InsertSearchResults<'tcx>> {
 617     let mut s = InsertSearcher {
 618         cx,
 619         map: contains_expr.map,
 620         key: contains_expr.key,
 621         ctxt: expr.span.ctxt(),
 622         edits: Vec::new(),
 623         is_map_used: false,
 624         allow_insert_closure: true,
 625         can_use_entry: true,
 626         in_tail_pos: true,
 627         is_single_insert: true,
 628         loops: Vec::new(),
 629         locals: HirIdSet::default(),
 630     };
 631     s.visit_expr(expr);
 632     let allow_insert_closure = s.allow_insert_closure;
 633     let is_single_insert = s.is_single_insert;
 634     let edits = s.edits;
 635     s.can_use_entry.then_some(InsertSearchResults {
 636         edits,
 637         allow_insert_closure,
 638         is_single_insert,
 639     })
 640 }