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 (cond_expr, then_expr, else_expr) = match higher::If::hir(expr) {
  69             Some(higher::If { cond, then, r#else }) => (cond, then, r#else),
  70             _ => return,
  71         };
  72
  73         let (map_ty, contains_expr) = match try_parse_contains(cx, cond_expr) {
  74             Some(x) => x,
  75             None => return,
  76         };
  77
  78         let then_search = match find_insert_calls(cx, &contains_expr, then_expr) {
  79             Some(x) => x,
  80             None => return,
  81         };
  82
  83         let mut app = Applicability::MachineApplicable;
  84         let map_str = snippet_with_context(cx, contains_expr.map.span, contains_expr.call_ctxt, "..", &mut app).0;
  85         let key_str = snippet_with_context(cx, contains_expr.key.span, contains_expr.call_ctxt, "..", &mut app).0;
  86         let sugg = if let Some(else_expr) = else_expr {
  87             let else_search = match find_insert_calls(cx, &contains_expr, else_expr) {
  88                 Some(search) => search,
  89                 None => return,
  90             };
  91
  92             if then_search.edits.is_empty() && else_search.edits.is_empty() {
  93                 // No insertions
  94                 return;
  95             } else if then_search.edits.is_empty() || else_search.edits.is_empty() {
  96                 // if .. { insert } else { .. } or if .. { .. } else { insert }
  97                 let ((then_str, entry_kind), else_str) = match (else_search.edits.is_empty(), contains_expr.negated) {
  98                     (true, true) => (
  99                         then_search.snippet_vacant(cx, then_expr.span, &mut app),
 100                         snippet_with_applicability(cx, else_expr.span, "{ .. }", &mut app),
 101                     ),
 102                     (true, false) => (
 103                         then_search.snippet_occupied(cx, then_expr.span, &mut app),
 104                         snippet_with_applicability(cx, else_expr.span, "{ .. }", &mut app),
 105                     ),
 106                     (false, true) => (
 107                         else_search.snippet_occupied(cx, else_expr.span, &mut app),
 108                         snippet_with_applicability(cx, then_expr.span, "{ .. }", &mut app),
 109                     ),
 110                     (false, false) => (
 111                         else_search.snippet_vacant(cx, else_expr.span, &mut app),
 112                         snippet_with_applicability(cx, then_expr.span, "{ .. }", &mut app),
 113                     ),
 114                 };
 115                 format!(
 116                     "if let {}::{entry_kind} = {map_str}.entry({key_str}) {then_str} else {else_str}",
 117                     map_ty.entry_path(),
 118                 )
 119             } else {
 120                 // if .. { insert } else { insert }
 121                 let ((then_str, then_entry), (else_str, else_entry)) = if contains_expr.negated {
 122                     (
 123                         then_search.snippet_vacant(cx, then_expr.span, &mut app),
 124                         else_search.snippet_occupied(cx, else_expr.span, &mut app),
 125                     )
 126                 } else {
 127                     (
 128                         then_search.snippet_occupied(cx, then_expr.span, &mut app),
 129                         else_search.snippet_vacant(cx, else_expr.span, &mut app),
 130                     )
 131                 };
 132                 let indent_str = snippet_indent(cx, expr.span);
 133                 let indent_str = indent_str.as_deref().unwrap_or("");
 134                 format!(
 135                     "match {map_str}.entry({key_str}) {{\n{indent_str}    {entry}::{then_entry} => {}\n\
 136                         {indent_str}    {entry}::{else_entry} => {}\n{indent_str}}}",
 137                     reindent_multiline(then_str.into(), true, Some(4 + indent_str.len())),
 138                     reindent_multiline(else_str.into(), true, Some(4 + indent_str.len())),
 139                     entry = map_ty.entry_path(),
 140                 )
 141             }
 142         } else {
 143             if then_search.edits.is_empty() {
 144                 // no insertions
 145                 return;
 146             }
 147
 148             // if .. { insert }
 149             if !then_search.allow_insert_closure {
 150                 let (body_str, entry_kind) = if contains_expr.negated {
 151                     then_search.snippet_vacant(cx, then_expr.span, &mut app)
 152                 } else {
 153                     then_search.snippet_occupied(cx, then_expr.span, &mut app)
 154                 };
 155                 format!(
 156                     "if let {}::{entry_kind} = {map_str}.entry({key_str}) {body_str}",
 157                     map_ty.entry_path(),
 158                 )
 159             } else if let Some(insertion) = then_search.as_single_insertion() {
 160                 let value_str = snippet_with_context(cx, insertion.value.span, then_expr.span.ctxt(), "..", &mut app).0;
 161                 if contains_expr.negated {
 162                     if insertion.value.can_have_side_effects() {
 163                         format!("{map_str}.entry({key_str}).or_insert_with(|| {value_str});")
 164                     } else {
 165                         format!("{map_str}.entry({key_str}).or_insert({value_str});")
 166                     }
 167                 } else {
 168                     // TODO: suggest using `if let Some(v) = map.get_mut(k) { .. }` here.
 169                     // This would need to be a different lint.
 170                     return;
 171                 }
 172             } else {
 173                 let block_str = then_search.snippet_closure(cx, then_expr.span, &mut app);
 174                 if contains_expr.negated {
 175                     format!("{map_str}.entry({key_str}).or_insert_with(|| {block_str});")
 176                 } else {
 177                     // TODO: suggest using `if let Some(v) = map.get_mut(k) { .. }` here.
 178                     // This would need to be a different lint.
 179                     return;
 180                 }
 181             }
 182         };
 183
 184         span_lint_and_sugg(
 185             cx,
 186             MAP_ENTRY,
 187             expr.span,
 188             &format!("usage of `contains_key` followed by `insert` on a `{}`", map_ty.name()),
 189             "try this",
 190             sugg,
 191             app,
 192         );
 193     }
 194 }
 195
 196 #[derive(Clone, Copy)]
 197 enum MapType {
 198     Hash,
 199     BTree,
 200 }
 201 impl MapType {
 202     fn name(self) -> &'static str {
 203         match self {
 204             Self::Hash => "HashMap",
 205             Self::BTree => "BTreeMap",
 206         }
 207     }
 208     fn entry_path(self) -> &'static str {
 209         match self {
 210             Self::Hash => "std::collections::hash_map::Entry",
 211             Self::BTree => "std::collections::btree_map::Entry",
 212         }
 213     }
 214 }
 215
 216 struct ContainsExpr<'tcx> {
 217     negated: bool,
 218     map: &'tcx Expr<'tcx>,
 219     key: &'tcx Expr<'tcx>,
 220     call_ctxt: SyntaxContext,
 221 }
 222 fn try_parse_contains<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<(MapType, ContainsExpr<'tcx>)> {
 223     let mut negated = false;
 224     let expr = peel_hir_expr_while(expr, |e| match e.kind {
 225         ExprKind::Unary(UnOp::Not, e) => {
 226             negated = !negated;
 227             Some(e)
 228         },
 229         _ => None,
 230     });
 231     match expr.kind {
 232         ExprKind::MethodCall(
 233             _,
 234             map,
 235             [
 236                 Expr {
 237                     kind: ExprKind::AddrOf(_, _, key),
 238                     span: key_span,
 239                     ..
 240                 },
 241             ],
 242             _,
 243         ) if key_span.ctxt() == expr.span.ctxt() => {
 244             let id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
 245             let expr = ContainsExpr {
 246                 negated,
 247                 map,
 248                 key,
 249                 call_ctxt: expr.span.ctxt(),
 250             };
 251             if match_def_path(cx, id, &paths::BTREEMAP_CONTAINS_KEY) {
 252                 Some((MapType::BTree, expr))
 253             } else if match_def_path(cx, id, &paths::HASHMAP_CONTAINS_KEY) {
 254                 Some((MapType::Hash, expr))
 255             } else {
 256                 None
 257             }
 258         },
 259         _ => None,
 260     }
 261 }
 262
 263 struct InsertExpr<'tcx> {
 264     map: &'tcx Expr<'tcx>,
 265     key: &'tcx Expr<'tcx>,
 266     value: &'tcx Expr<'tcx>,
 267 }
 268 fn try_parse_insert<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<InsertExpr<'tcx>> {
 269     if let ExprKind::MethodCall(_, map, [key, value], _) = expr.kind {
 270         let id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
 271         if match_def_path(cx, id, &paths::BTREEMAP_INSERT) || match_def_path(cx, id, &paths::HASHMAP_INSERT) {
 272             Some(InsertExpr { map, key, value })
 273         } else {
 274             None
 275         }
 276     } else {
 277         None
 278     }
 279 }
 280
 281 /// An edit that will need to be made to move the expression to use the entry api
 282 #[derive(Clone, Copy)]
 283 enum Edit<'tcx> {
 284     /// A semicolon that needs to be removed. Used to create a closure for `insert_with`.
 285     RemoveSemi(Span),
 286     /// An insertion into the map.
 287     Insertion(Insertion<'tcx>),
 288 }
 289 impl<'tcx> Edit<'tcx> {
 290     fn as_insertion(self) -> Option<Insertion<'tcx>> {
 291         if let Self::Insertion(i) = self { Some(i) } else { None }
 292     }
 293 }
 294 #[derive(Clone, Copy)]
 295 struct Insertion<'tcx> {
 296     call: &'tcx Expr<'tcx>,
 297     value: &'tcx Expr<'tcx>,
 298 }
 299
 300 /// This visitor needs to do a multiple things:
 301 /// * Find all usages of the map. An insertion can only be made before any other usages of the map.
 302 /// * Determine if there's an insertion using the same key. There's no need for the entry api
 303 ///   otherwise.
 304 /// * Determine if the final statement executed is an insertion. This is needed to use
 305 ///   `or_insert_with`.
 306 /// * Determine if there's any sub-expression that can't be placed in a closure.
 307 /// * Determine if there's only a single insert statement. `or_insert` can be used in this case.
 308 #[expect(clippy::struct_excessive_bools)]
 309 struct InsertSearcher<'cx, 'tcx> {
 310     cx: &'cx LateContext<'tcx>,
 311     /// The map expression used in the contains call.
 312     map: &'tcx Expr<'tcx>,
 313     /// The key expression used in the contains call.
 314     key: &'tcx Expr<'tcx>,
 315     /// The context of the top level block. All insert calls must be in the same context.
 316     ctxt: SyntaxContext,
 317     /// Whether this expression can be safely moved into a closure.
 318     allow_insert_closure: bool,
 319     /// Whether this expression can use the entry api.
 320     can_use_entry: bool,
 321     /// Whether this expression is the final expression in this code path. This may be a statement.
 322     in_tail_pos: bool,
 323     // Is this expression a single insert. A slightly better suggestion can be made in this case.
 324     is_single_insert: bool,
 325     /// If the visitor has seen the map being used.
 326     is_map_used: bool,
 327     /// The locations where changes need to be made for the suggestion.
 328     edits: Vec<Edit<'tcx>>,
 329     /// A stack of loops the visitor is currently in.
 330     loops: Vec<HirId>,
 331     /// Local variables created in the expression. These don't need to be captured.
 332     locals: HirIdSet,
 333 }
 334 impl<'tcx> InsertSearcher<'_, 'tcx> {
 335     /// Visit the expression as a branch in control flow. Multiple insert calls can be used, but
 336     /// only if they are on separate code paths. This will return whether the map was used in the
 337     /// given expression.
 338     fn visit_cond_arm(&mut self, e: &'tcx Expr<'_>) -> bool {
 339         let is_map_used = self.is_map_used;
 340         let in_tail_pos = self.in_tail_pos;
 341         self.visit_expr(e);
 342         let res = self.is_map_used;
 343         self.is_map_used = is_map_used;
 344         self.in_tail_pos = in_tail_pos;
 345         res
 346     }
 347
 348     /// Visits an expression which is not itself in a tail position, but other sibling expressions
 349     /// may be. e.g. if conditions
 350     fn visit_non_tail_expr(&mut self, e: &'tcx Expr<'_>) {
 351         let in_tail_pos = self.in_tail_pos;
 352         self.in_tail_pos = false;
 353         self.visit_expr(e);
 354         self.in_tail_pos = in_tail_pos;
 355     }
 356 }
 357 impl<'tcx> Visitor<'tcx> for InsertSearcher<'_, 'tcx> {
 358     fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) {
 359         match stmt.kind {
 360             StmtKind::Semi(e) => {
 361                 self.visit_expr(e);
 362
 363                 if self.in_tail_pos && self.allow_insert_closure {
 364                     // The spans are used to slice the top level expression into multiple parts. This requires that
 365                     // they all come from the same part of the source code.
 366                     if stmt.span.ctxt() == self.ctxt && e.span.ctxt() == self.ctxt {
 367                         self.edits
 368                             .push(Edit::RemoveSemi(stmt.span.trim_start(e.span).unwrap_or(DUMMY_SP)));
 369                     } else {
 370                         self.allow_insert_closure = false;
 371                     }
 372                 }
 373             },
 374             StmtKind::Expr(e) => self.visit_expr(e),
 375             StmtKind::Local(l) => {
 376                 self.visit_pat(l.pat);
 377                 if let Some(e) = l.init {
 378                     self.allow_insert_closure &= !self.in_tail_pos;
 379                     self.in_tail_pos = false;
 380                     self.is_single_insert = false;
 381                     self.visit_expr(e);
 382                 }
 383             },
 384             StmtKind::Item(_) => {
 385                 self.allow_insert_closure &= !self.in_tail_pos;
 386                 self.is_single_insert = false;
 387             },
 388         }
 389     }
 390
 391     fn visit_block(&mut self, block: &'tcx Block<'_>) {
 392         // If the block is in a tail position, then the last expression (possibly a statement) is in the
 393         // tail position. The rest, however, are not.
 394         match (block.stmts, block.expr) {
 395             ([], None) => {
 396                 self.allow_insert_closure &= !self.in_tail_pos;
 397             },
 398             ([], Some(expr)) => self.visit_expr(expr),
 399             (stmts, Some(expr)) => {
 400                 let in_tail_pos = self.in_tail_pos;
 401                 self.in_tail_pos = false;
 402                 for stmt in stmts {
 403                     self.visit_stmt(stmt);
 404                 }
 405                 self.in_tail_pos = in_tail_pos;
 406                 self.visit_expr(expr);
 407             },
 408             ([stmts @ .., stmt], None) => {
 409                 let in_tail_pos = self.in_tail_pos;
 410                 self.in_tail_pos = false;
 411                 for stmt in stmts {
 412                     self.visit_stmt(stmt);
 413                 }
 414                 self.in_tail_pos = in_tail_pos;
 415                 self.visit_stmt(stmt);
 416             },
 417         }
 418     }
 419
 420     fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
 421         if !self.can_use_entry {
 422             return;
 423         }
 424
 425         match try_parse_insert(self.cx, expr) {
 426             Some(insert_expr) if SpanlessEq::new(self.cx).eq_expr(self.map, insert_expr.map) => {
 427                 // Multiple inserts, inserts with a different key, and inserts from a macro can't use the entry api.
 428                 if self.is_map_used
 429                     || !SpanlessEq::new(self.cx).eq_expr(self.key, insert_expr.key)
 430                     || expr.span.ctxt() != self.ctxt
 431                 {
 432                     self.can_use_entry = false;
 433                     return;
 434                 }
 435
 436                 self.edits.push(Edit::Insertion(Insertion {
 437                     call: expr,
 438                     value: insert_expr.value,
 439                 }));
 440                 self.is_map_used = true;
 441                 self.allow_insert_closure &= self.in_tail_pos;
 442
 443                 // The value doesn't affect whether there is only a single insert expression.
 444                 let is_single_insert = self.is_single_insert;
 445                 self.visit_non_tail_expr(insert_expr.value);
 446                 self.is_single_insert = is_single_insert;
 447             },
 448             _ if SpanlessEq::new(self.cx).eq_expr(self.map, expr) => {
 449                 self.is_map_used = true;
 450             },
 451             _ => match expr.kind {
 452                 ExprKind::If(cond_expr, then_expr, Some(else_expr)) => {
 453                     self.is_single_insert = false;
 454                     self.visit_non_tail_expr(cond_expr);
 455                     // Each branch may contain it's own insert expression.
 456                     let mut is_map_used = self.visit_cond_arm(then_expr);
 457                     is_map_used |= self.visit_cond_arm(else_expr);
 458                     self.is_map_used = is_map_used;
 459                 },
 460                 ExprKind::Match(scrutinee_expr, arms, _) => {
 461                     self.is_single_insert = false;
 462                     self.visit_non_tail_expr(scrutinee_expr);
 463                     // Each branch may contain it's own insert expression.
 464                     let mut is_map_used = self.is_map_used;
 465                     for arm in arms {
 466                         self.visit_pat(arm.pat);
 467                         if let Some(Guard::If(guard) | Guard::IfLet(&Let { init: guard, .. })) = arm.guard {
 468                             self.visit_non_tail_expr(guard);
 469                         }
 470                         is_map_used |= self.visit_cond_arm(arm.body);
 471                     }
 472                     self.is_map_used = is_map_used;
 473                 },
 474                 ExprKind::Loop(block, ..) => {
 475                     self.loops.push(expr.hir_id);
 476                     self.is_single_insert = false;
 477                     self.allow_insert_closure &= !self.in_tail_pos;
 478                     // Don't allow insertions inside of a loop.
 479                     let edit_len = self.edits.len();
 480                     self.visit_block(block);
 481                     if self.edits.len() != edit_len {
 482                         self.can_use_entry = false;
 483                     }
 484                     self.loops.pop();
 485                 },
 486                 ExprKind::Block(block, _) => self.visit_block(block),
 487                 ExprKind::InlineAsm(_) => {
 488                     self.can_use_entry = false;
 489                 },
 490                 _ => {
 491                     self.allow_insert_closure &= !self.in_tail_pos;
 492                     self.allow_insert_closure &=
 493                         can_move_expr_to_closure_no_visit(self.cx, expr, &self.loops, &self.locals);
 494                     // Sub expressions are no longer in the tail position.
 495                     self.is_single_insert = false;
 496                     self.in_tail_pos = false;
 497                     walk_expr(self, expr);
 498                 },
 499             },
 500         }
 501     }
 502
 503     fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
 504         p.each_binding_or_first(&mut |_, id, _, _| {
 505             self.locals.insert(id);
 506         });
 507     }
 508 }
 509
 510 struct InsertSearchResults<'tcx> {
 511     edits: Vec<Edit<'tcx>>,
 512     allow_insert_closure: bool,
 513     is_single_insert: bool,
 514 }
 515 impl<'tcx> InsertSearchResults<'tcx> {
 516     fn as_single_insertion(&self) -> Option<Insertion<'tcx>> {
 517         self.is_single_insert.then(|| self.edits[0].as_insertion().unwrap())
 518     }
 519
 520     fn snippet(
 521         &self,
 522         cx: &LateContext<'_>,
 523         mut span: Span,
 524         app: &mut Applicability,
 525         write_wrapped: impl Fn(&mut String, Insertion<'_>, SyntaxContext, &mut Applicability),
 526     ) -> String {
 527         let ctxt = span.ctxt();
 528         let mut res = String::new();
 529         for insertion in self.edits.iter().filter_map(|e| e.as_insertion()) {
 530             res.push_str(&snippet_with_applicability(
 531                 cx,
 532                 span.until(insertion.call.span),
 533                 "..",
 534                 app,
 535             ));
 536             if is_expr_used_or_unified(cx.tcx, insertion.call) {
 537                 write_wrapped(&mut res, insertion, ctxt, app);
 538             } else {
 539                 let _ = write!(
 540                     res,
 541                     "e.insert({})",
 542                     snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0
 543                 );
 544             }
 545             span = span.trim_start(insertion.call.span).unwrap_or(DUMMY_SP);
 546         }
 547         res.push_str(&snippet_with_applicability(cx, span, "..", app));
 548         res
 549     }
 550
 551     fn snippet_occupied(&self, cx: &LateContext<'_>, span: Span, app: &mut Applicability) -> (String, &'static str) {
 552         (
 553             self.snippet(cx, span, app, |res, insertion, ctxt, app| {
 554                 // Insertion into a map would return `Some(&mut value)`, but the entry returns `&mut value`
 555                 let _ = write!(
 556                     res,
 557                     "Some(e.insert({}))",
 558                     snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0
 559                 );
 560             }),
 561             "Occupied(mut e)",
 562         )
 563     }
 564
 565     fn snippet_vacant(&self, cx: &LateContext<'_>, span: Span, app: &mut Applicability) -> (String, &'static str) {
 566         (
 567             self.snippet(cx, span, app, |res, insertion, ctxt, app| {
 568                 // Insertion into a map would return `None`, but the entry returns a mutable reference.
 569                 let _ = if is_expr_final_block_expr(cx.tcx, insertion.call) {
 570                     write!(
 571                         res,
 572                         "e.insert({});\n{}None",
 573                         snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0,
 574                         snippet_indent(cx, insertion.call.span).as_deref().unwrap_or(""),
 575                     )
 576                 } else {
 577                     write!(
 578                         res,
 579                         "{{ e.insert({}); None }}",
 580                         snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0,
 581                     )
 582                 };
 583             }),
 584             "Vacant(e)",
 585         )
 586     }
 587
 588     fn snippet_closure(&self, cx: &LateContext<'_>, mut span: Span, app: &mut Applicability) -> String {
 589         let ctxt = span.ctxt();
 590         let mut res = String::new();
 591         for edit in &self.edits {
 592             match *edit {
 593                 Edit::Insertion(insertion) => {
 594                     // Cut out the value from `map.insert(key, value)`
 595                     res.push_str(&snippet_with_applicability(
 596                         cx,
 597                         span.until(insertion.call.span),
 598                         "..",
 599                         app,
 600                     ));
 601                     res.push_str(&snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0);
 602                     span = span.trim_start(insertion.call.span).unwrap_or(DUMMY_SP);
 603                 },
 604                 Edit::RemoveSemi(semi_span) => {
 605                     // Cut out the semicolon. This allows the value to be returned from the closure.
 606                     res.push_str(&snippet_with_applicability(cx, span.until(semi_span), "..", app));
 607                     span = span.trim_start(semi_span).unwrap_or(DUMMY_SP);
 608                 },
 609             }
 610         }
 611         res.push_str(&snippet_with_applicability(cx, span, "..", app));
 612         res
 613     }
 614 }
 615
 616 fn find_insert_calls<'tcx>(
 617     cx: &LateContext<'tcx>,
 618     contains_expr: &ContainsExpr<'tcx>,
 619     expr: &'tcx Expr<'_>,
 620 ) -> Option<InsertSearchResults<'tcx>> {
 621     let mut s = InsertSearcher {
 622         cx,
 623         map: contains_expr.map,
 624         key: contains_expr.key,
 625         ctxt: expr.span.ctxt(),
 626         edits: Vec::new(),
 627         is_map_used: false,
 628         allow_insert_closure: true,
 629         can_use_entry: true,
 630         in_tail_pos: true,
 631         is_single_insert: true,
 632         loops: Vec::new(),
 633         locals: HirIdSet::default(),
 634     };
 635     s.visit_expr(expr);
 636     let allow_insert_closure = s.allow_insert_closure;
 637     let is_single_insert = s.is_single_insert;
 638     let edits = s.edits;
 639     s.can_use_entry.then_some(InsertSearchResults {
 640         edits,
 641         allow_insert_closure,
 642         is_single_insert,
 643     })
 644 }