compiler/rustc_parse/src/parser/stmt.rs

   1 use super::attr::DEFAULT_INNER_ATTR_FORBIDDEN;
   2 use super::diagnostics::{AttemptLocalParseRecovery, Error};
   3 use super::expr::LhsExpr;
   4 use super::pat::RecoverComma;
   5 use super::path::PathStyle;
   6 use super::TrailingToken;
   7 use super::{
   8     AttrWrapper, BlockMode, FnParseMode, ForceCollect, Parser, Restrictions, SemiColonMode,
   9 };
  10 use crate::maybe_whole;
  11
  12 use rustc_ast as ast;
  13 use rustc_ast::ptr::P;
  14 use rustc_ast::token::{self, TokenKind};
  15 use rustc_ast::util::classify;
  16 use rustc_ast::{
  17     AstLike, AttrStyle, AttrVec, Attribute, LocalKind, MacCall, MacCallStmt, MacStmtStyle,
  18 };
  19 use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, Local, Stmt};
  20 use rustc_ast::{StmtKind, DUMMY_NODE_ID};
  21 use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult};
  22 use rustc_span::source_map::{BytePos, Span};
  23 use rustc_span::symbol::{kw, sym};
  24
  25 use std::mem;
  26
  27 impl<'a> Parser<'a> {
  28     /// Parses a statement. This stops just before trailing semicolons on everything but items.
  29     /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
  30     // Public for rustfmt usage.
  31     pub fn parse_stmt(&mut self, force_collect: ForceCollect) -> PResult<'a, Option<Stmt>> {
  32         Ok(self.parse_stmt_without_recovery(false, force_collect).unwrap_or_else(|mut e| {
  33             e.emit();
  34             self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
  35             None
  36         }))
  37     }
  38
  39     /// If `force_capture` is true, forces collection of tokens regardless of whether
  40     /// or not we have attributes
  41     crate fn parse_stmt_without_recovery(
  42         &mut self,
  43         capture_semi: bool,
  44         force_collect: ForceCollect,
  45     ) -> PResult<'a, Option<Stmt>> {
  46         let attrs = self.parse_outer_attributes()?;
  47         let lo = self.token.span;
  48
  49         // Don't use `maybe_whole` so that we have precise control
  50         // over when we bump the parser
  51         if let token::Interpolated(nt) = &self.token.kind && let token::NtStmt(stmt) = &**nt {
  52             let mut stmt = stmt.clone();
  53             self.bump();
  54             stmt.visit_attrs(|stmt_attrs| {
  55                 attrs.prepend_to_nt_inner(stmt_attrs);
  56             });
  57             return Ok(Some(stmt.into_inner()));
  58         }
  59
  60         Ok(Some(if self.token.is_keyword(kw::Let) {
  61             self.parse_local_mk(lo, attrs, capture_semi, force_collect)?
  62         } else if self.is_kw_followed_by_ident(kw::Mut) {
  63             self.recover_stmt_local(lo, attrs, "missing keyword", "let mut")?
  64         } else if self.is_kw_followed_by_ident(kw::Auto) {
  65             self.bump(); // `auto`
  66             let msg = "write `let` instead of `auto` to introduce a new variable";
  67             self.recover_stmt_local(lo, attrs, msg, "let")?
  68         } else if self.is_kw_followed_by_ident(sym::var) {
  69             self.bump(); // `var`
  70             let msg = "write `let` instead of `var` to introduce a new variable";
  71             self.recover_stmt_local(lo, attrs, msg, "let")?
  72         } else if self.check_path() && !self.token.is_qpath_start() && !self.is_path_start_item() {
  73             // We have avoided contextual keywords like `union`, items with `crate` visibility,
  74             // or `auto trait` items. We aim to parse an arbitrary path `a::b` but not something
  75             // that starts like a path (1 token), but it fact not a path.
  76             // Also, we avoid stealing syntax from `parse_item_`.
  77             if force_collect == ForceCollect::Yes {
  78                 self.collect_tokens_no_attrs(|this| this.parse_stmt_path_start(lo, attrs))
  79             } else {
  80                 self.parse_stmt_path_start(lo, attrs)
  81             }?
  82         } else if let Some(item) = self.parse_item_common(
  83             attrs.clone(),
  84             false,
  85             true,
  86             FnParseMode { req_name: |_| true, req_body: true },
  87             force_collect,
  88         )? {
  89             // FIXME: Bad copy of attrs
  90             self.mk_stmt(lo.to(item.span), StmtKind::Item(P(item)))
  91         } else if self.eat(&token::Semi) {
  92             // Do not attempt to parse an expression if we're done here.
  93             self.error_outer_attrs(&attrs.take_for_recovery());
  94             self.mk_stmt(lo, StmtKind::Empty)
  95         } else if self.token != token::CloseDelim(token::Brace) {
  96             // Remainder are line-expr stmts.
  97             let e = if force_collect == ForceCollect::Yes {
  98                 self.collect_tokens_no_attrs(|this| {
  99                     this.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
 100                 })
 101             } else {
 102                 self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
 103             }?;
 104             if matches!(e.kind, ExprKind::Assign(..)) && self.eat_keyword(kw::Else) {
 105                 let bl = self.parse_block()?;
 106                 // Destructuring assignment ... else.
 107                 // This is not allowed, but point it out in a nice way.
 108                 let mut err = self.struct_span_err(
 109                     e.span.to(bl.span),
 110                     "<assignment> ... else { ... } is not allowed",
 111                 );
 112                 err.emit();
 113             }
 114             self.mk_stmt(lo.to(e.span), StmtKind::Expr(e))
 115         } else {
 116             self.error_outer_attrs(&attrs.take_for_recovery());
 117             return Ok(None);
 118         }))
 119     }
 120
 121     fn parse_stmt_path_start(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> {
 122         let stmt = self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
 123             let path = this.parse_path(PathStyle::Expr)?;
 124
 125             if this.eat(&token::Not) {
 126                 let stmt_mac = this.parse_stmt_mac(lo, attrs.into(), path)?;
 127                 if this.token == token::Semi {
 128                     return Ok((stmt_mac, TrailingToken::Semi));
 129                 } else {
 130                     return Ok((stmt_mac, TrailingToken::None));
 131                 }
 132             }
 133
 134             let expr = if this.eat(&token::OpenDelim(token::Brace)) {
 135                 this.parse_struct_expr(None, path, AttrVec::new(), true)?
 136             } else {
 137                 let hi = this.prev_token.span;
 138                 this.mk_expr(lo.to(hi), ExprKind::Path(None, path), AttrVec::new())
 139             };
 140
 141             let expr = this.with_res(Restrictions::STMT_EXPR, |this| {
 142                 this.parse_dot_or_call_expr_with(expr, lo, attrs)
 143             })?;
 144             // `DUMMY_SP` will get overwritten later in this function
 145             Ok((this.mk_stmt(rustc_span::DUMMY_SP, StmtKind::Expr(expr)), TrailingToken::None))
 146         })?;
 147
 148         if let StmtKind::Expr(expr) = stmt.kind {
 149             // Perform this outside of the `collect_tokens_trailing_token` closure,
 150             // since our outer attributes do not apply to this part of the expression
 151             let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
 152                 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
 153             })?;
 154             Ok(self.mk_stmt(lo.to(self.prev_token.span), StmtKind::Expr(expr)))
 155         } else {
 156             Ok(stmt)
 157         }
 158     }
 159
 160     /// Parses a statement macro `mac!(args)` provided a `path` representing `mac`.
 161     /// At this point, the `!` token after the path has already been eaten.
 162     fn parse_stmt_mac(&mut self, lo: Span, attrs: AttrVec, path: ast::Path) -> PResult<'a, Stmt> {
 163         let args = self.parse_mac_args()?;
 164         let delim = args.delim();
 165         let hi = self.prev_token.span;
 166
 167         let style = match delim {
 168             Some(token::Brace) => MacStmtStyle::Braces,
 169             Some(_) => MacStmtStyle::NoBraces,
 170             None => unreachable!(),
 171         };
 172
 173         let mac = MacCall { path, args, prior_type_ascription: self.last_type_ascription };
 174
 175         let kind = if (style == MacStmtStyle::Braces
 176             && self.token != token::Dot
 177             && self.token != token::Question)
 178             || self.token == token::Semi
 179             || self.token == token::Eof
 180         {
 181             StmtKind::MacCall(P(MacCallStmt { mac, style, attrs, tokens: None }))
 182         } else {
 183             // Since none of the above applied, this is an expression statement macro.
 184             let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac), AttrVec::new());
 185             let e = self.maybe_recover_from_bad_qpath(e, true)?;
 186             let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
 187             let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
 188             StmtKind::Expr(e)
 189         };
 190         Ok(self.mk_stmt(lo.to(hi), kind))
 191     }
 192
 193     /// Error on outer attributes in this context.
 194     /// Also error if the previous token was a doc comment.
 195     fn error_outer_attrs(&self, attrs: &[Attribute]) {
 196         if let [.., last] = attrs {
 197             if last.is_doc_comment() {
 198                 self.span_err(last.span, Error::UselessDocComment).emit();
 199             } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
 200                 self.struct_span_err(last.span, "expected statement after outer attribute").emit();
 201             }
 202         }
 203     }
 204
 205     fn recover_stmt_local(
 206         &mut self,
 207         lo: Span,
 208         attrs: AttrWrapper,
 209         msg: &str,
 210         sugg: &str,
 211     ) -> PResult<'a, Stmt> {
 212         let stmt = self.recover_local_after_let(lo, attrs)?;
 213         self.struct_span_err(lo, "invalid variable declaration")
 214             .span_suggestion(lo, msg, sugg.to_string(), Applicability::MachineApplicable)
 215             .emit();
 216         Ok(stmt)
 217     }
 218
 219     fn parse_local_mk(
 220         &mut self,
 221         lo: Span,
 222         attrs: AttrWrapper,
 223         capture_semi: bool,
 224         force_collect: ForceCollect,
 225     ) -> PResult<'a, Stmt> {
 226         self.collect_tokens_trailing_token(attrs, force_collect, |this, attrs| {
 227             this.expect_keyword(kw::Let)?;
 228             let local = this.parse_local(attrs.into())?;
 229             let trailing = if capture_semi && this.token.kind == token::Semi {
 230                 TrailingToken::Semi
 231             } else {
 232                 TrailingToken::None
 233             };
 234             Ok((this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)), trailing))
 235         })
 236     }
 237
 238     fn recover_local_after_let(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> {
 239         self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
 240             let local = this.parse_local(attrs.into())?;
 241             // FIXME - maybe capture semicolon in recovery?
 242             Ok((
 243                 this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)),
 244                 TrailingToken::None,
 245             ))
 246         })
 247     }
 248
 249     /// Parses a local variable declaration.
 250     fn parse_local(&mut self, attrs: AttrVec) -> PResult<'a, P<Local>> {
 251         let lo = self.prev_token.span;
 252         let (pat, colon) = self.parse_pat_before_ty(None, RecoverComma::Yes, "`let` bindings")?;
 253
 254         let (err, ty) = if colon {
 255             // Save the state of the parser before parsing type normally, in case there is a `:`
 256             // instead of an `=` typo.
 257             let parser_snapshot_before_type = self.clone();
 258             let colon_sp = self.prev_token.span;
 259             match self.parse_ty() {
 260                 Ok(ty) => (None, Some(ty)),
 261                 Err(mut err) => {
 262                     if let Ok(snip) = self.span_to_snippet(pat.span) {
 263                         err.span_label(pat.span, format!("while parsing the type for `{}`", snip));
 264                     }
 265                     let err = if self.check(&token::Eq) {
 266                         err.emit();
 267                         None
 268                     } else {
 269                         // Rewind to before attempting to parse the type and continue parsing.
 270                         let parser_snapshot_after_type =
 271                             mem::replace(self, parser_snapshot_before_type);
 272                         Some((parser_snapshot_after_type, colon_sp, err))
 273                     };
 274                     (err, None)
 275                 }
 276             }
 277         } else {
 278             (None, None)
 279         };
 280         let init = match (self.parse_initializer(err.is_some()), err) {
 281             (Ok(init), None) => {
 282                 // init parsed, ty parsed
 283                 init
 284             }
 285             (Ok(init), Some((_, colon_sp, mut err))) => {
 286                 // init parsed, ty error
 287                 // Could parse the type as if it were the initializer, it is likely there was a
 288                 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
 289                 err.span_suggestion_short(
 290                     colon_sp,
 291                     "use `=` if you meant to assign",
 292                     " =".to_string(),
 293                     Applicability::MachineApplicable,
 294                 );
 295                 err.emit();
 296                 // As this was parsed successfully, continue as if the code has been fixed for the
 297                 // rest of the file. It will still fail due to the emitted error, but we avoid
 298                 // extra noise.
 299                 init
 300             }
 301             (Err(init_err), Some((snapshot, _, ty_err))) => {
 302                 // init error, ty error
 303                 init_err.cancel();
 304                 // Couldn't parse the type nor the initializer, only raise the type error and
 305                 // return to the parser state before parsing the type as the initializer.
 306                 // let x: <parse_error>;
 307                 *self = snapshot;
 308                 return Err(ty_err);
 309             }
 310             (Err(err), None) => {
 311                 // init error, ty parsed
 312                 // Couldn't parse the initializer and we're not attempting to recover a failed
 313                 // parse of the type, return the error.
 314                 return Err(err);
 315             }
 316         };
 317         let kind = match init {
 318             None => LocalKind::Decl,
 319             Some(init) => {
 320                 if self.eat_keyword(kw::Else) {
 321                     if self.token.is_keyword(kw::If) {
 322                         // `let...else if`. Emit the same error that `parse_block()` would,
 323                         // but explicitly point out that this pattern is not allowed.
 324                         let msg = "conditional `else if` is not supported for `let...else`";
 325                         return Err(self.error_block_no_opening_brace_msg(msg));
 326                     }
 327                     let els = self.parse_block()?;
 328                     self.check_let_else_init_bool_expr(&init);
 329                     self.check_let_else_init_trailing_brace(&init);
 330                     LocalKind::InitElse(init, els)
 331                 } else {
 332                     LocalKind::Init(init)
 333                 }
 334             }
 335         };
 336         let hi = if self.token == token::Semi { self.token.span } else { self.prev_token.span };
 337         Ok(P(ast::Local { ty, pat, kind, id: DUMMY_NODE_ID, span: lo.to(hi), attrs, tokens: None }))
 338     }
 339
 340     fn check_let_else_init_bool_expr(&self, init: &ast::Expr) {
 341         if let ast::ExprKind::Binary(op, ..) = init.kind {
 342             if op.node.lazy() {
 343                 let suggs = vec![
 344                     (init.span.shrink_to_lo(), "(".to_string()),
 345                     (init.span.shrink_to_hi(), ")".to_string()),
 346                 ];
 347                 self.struct_span_err(
 348                     init.span,
 349                     &format!(
 350                         "a `{}` expression cannot be directly assigned in `let...else`",
 351                         op.node.to_string()
 352                     ),
 353                 )
 354                 .multipart_suggestion(
 355                     "wrap the expression in parentheses",
 356                     suggs,
 357                     Applicability::MachineApplicable,
 358                 )
 359                 .emit();
 360             }
 361         }
 362     }
 363
 364     fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) {
 365         if let Some(trailing) = classify::expr_trailing_brace(init) {
 366             let err_span = trailing.span.with_lo(trailing.span.hi() - BytePos(1));
 367             let suggs = vec![
 368                 (trailing.span.shrink_to_lo(), "(".to_string()),
 369                 (trailing.span.shrink_to_hi(), ")".to_string()),
 370             ];
 371             self.struct_span_err(
 372                 err_span,
 373                 "right curly brace `}` before `else` in a `let...else` statement not allowed",
 374             )
 375             .multipart_suggestion(
 376                 "try wrapping the expression in parentheses",
 377                 suggs,
 378                 Applicability::MachineApplicable,
 379             )
 380             .emit();
 381         }
 382     }
 383
 384     /// Parses the RHS of a local variable declaration (e.g., `= 14;`).
 385     fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<P<Expr>>> {
 386         let eq_consumed = match self.token.kind {
 387             token::BinOpEq(..) => {
 388                 // Recover `let x <op>= 1` as `let x = 1`
 389                 self.struct_span_err(
 390                     self.token.span,
 391                     "can't reassign to an uninitialized variable",
 392                 )
 393                 .span_suggestion_short(
 394                     self.token.span,
 395                     "initialize the variable",
 396                     "=".to_string(),
 397                     Applicability::MaybeIncorrect,
 398                 )
 399                 .help("if you meant to overwrite, remove the `let` binding")
 400                 .emit();
 401                 self.bump();
 402                 true
 403             }
 404             _ => self.eat(&token::Eq),
 405         };
 406
 407         Ok(if eq_consumed || eq_optional { Some(self.parse_expr()?) } else { None })
 408     }
 409
 410     /// Parses a block. No inner attributes are allowed.
 411     pub(super) fn parse_block(&mut self) -> PResult<'a, P<Block>> {
 412         let (attrs, block) = self.parse_inner_attrs_and_block()?;
 413         if let [.., last] = &*attrs {
 414             self.error_on_forbidden_inner_attr(last.span, DEFAULT_INNER_ATTR_FORBIDDEN);
 415         }
 416         Ok(block)
 417     }
 418
 419     fn error_block_no_opening_brace_msg(
 420         &mut self,
 421         msg: &str,
 422     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
 423         let sp = self.token.span;
 424         let mut e = self.struct_span_err(sp, msg);
 425         let do_not_suggest_help = self.token.is_keyword(kw::In) || self.token == token::Colon;
 426
 427         // Check to see if the user has written something like
 428         //
 429         //    if (cond)
 430         //      bar;
 431         //
 432         // which is valid in other languages, but not Rust.
 433         match self.parse_stmt_without_recovery(false, ForceCollect::No) {
 434             // If the next token is an open brace (e.g., `if a b {`), the place-
 435             // inside-a-block suggestion would be more likely wrong than right.
 436             Ok(Some(_))
 437                 if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
 438                     || do_not_suggest_help => {}
 439             // Do not suggest `if foo println!("") {;}` (as would be seen in test for #46836).
 440             Ok(Some(Stmt { kind: StmtKind::Empty, .. })) => {}
 441             Ok(Some(stmt)) => {
 442                 let stmt_own_line = self.sess.source_map().is_line_before_span_empty(sp);
 443                 let stmt_span = if stmt_own_line && self.eat(&token::Semi) {
 444                     // Expand the span to include the semicolon.
 445                     stmt.span.with_hi(self.prev_token.span.hi())
 446                 } else {
 447                     stmt.span
 448                 };
 449                 e.multipart_suggestion(
 450                     "try placing this code inside a block",
 451                     vec![
 452                         (stmt_span.shrink_to_lo(), "{ ".to_string()),
 453                         (stmt_span.shrink_to_hi(), " }".to_string()),
 454                     ],
 455                     // Speculative; has been misleading in the past (#46836).
 456                     Applicability::MaybeIncorrect,
 457                 );
 458             }
 459             Err(e) => {
 460                 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
 461                 e.cancel();
 462             }
 463             _ => {}
 464         }
 465         e.span_label(sp, "expected `{`");
 466         e
 467     }
 468
 469     fn error_block_no_opening_brace<T>(&mut self) -> PResult<'a, T> {
 470         let tok = super::token_descr(&self.token);
 471         let msg = format!("expected `{{`, found {}", tok);
 472         Err(self.error_block_no_opening_brace_msg(&msg))
 473     }
 474
 475     /// Parses a block. Inner attributes are allowed.
 476     pub(super) fn parse_inner_attrs_and_block(
 477         &mut self,
 478     ) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
 479         self.parse_block_common(self.token.span, BlockCheckMode::Default)
 480     }
 481
 482     /// Parses a block. Inner attributes are allowed.
 483     pub(super) fn parse_block_common(
 484         &mut self,
 485         lo: Span,
 486         blk_mode: BlockCheckMode,
 487     ) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
 488         maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
 489
 490         self.maybe_recover_unexpected_block_label();
 491         if !self.eat(&token::OpenDelim(token::Brace)) {
 492             return self.error_block_no_opening_brace();
 493         }
 494
 495         let attrs = self.parse_inner_attributes()?;
 496         let tail = match self.maybe_suggest_struct_literal(lo, blk_mode) {
 497             Some(tail) => tail?,
 498             None => self.parse_block_tail(lo, blk_mode, AttemptLocalParseRecovery::Yes)?,
 499         };
 500         Ok((attrs, tail))
 501     }
 502
 503     /// Parses the rest of a block expression or function body.
 504     /// Precondition: already parsed the '{'.
 505     crate fn parse_block_tail(
 506         &mut self,
 507         lo: Span,
 508         s: BlockCheckMode,
 509         recover: AttemptLocalParseRecovery,
 510     ) -> PResult<'a, P<Block>> {
 511         let mut stmts = vec![];
 512         while !self.eat(&token::CloseDelim(token::Brace)) {
 513             if self.token == token::Eof {
 514                 break;
 515             }
 516             let stmt = match self.parse_full_stmt(recover) {
 517                 Err(mut err) if recover.yes() => {
 518                     self.maybe_annotate_with_ascription(&mut err, false);
 519                     err.emit();
 520                     self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
 521                     Some(self.mk_stmt_err(self.token.span))
 522                 }
 523                 Ok(stmt) => stmt,
 524                 Err(err) => return Err(err),
 525             };
 526             if let Some(stmt) = stmt {
 527                 stmts.push(stmt);
 528             } else {
 529                 // Found only `;` or `}`.
 530                 continue;
 531             };
 532         }
 533         Ok(self.mk_block(stmts, s, lo.to(self.prev_token.span)))
 534     }
 535
 536     /// Parses a statement, including the trailing semicolon.
 537     pub fn parse_full_stmt(
 538         &mut self,
 539         recover: AttemptLocalParseRecovery,
 540     ) -> PResult<'a, Option<Stmt>> {
 541         // Skip looking for a trailing semicolon when we have an interpolated statement.
 542         maybe_whole!(self, NtStmt, |x| Some(x.into_inner()));
 543
 544         let Some(mut stmt) = self.parse_stmt_without_recovery(true, ForceCollect::No)? else {
 545             return Ok(None);
 546         };
 547
 548         let mut eat_semi = true;
 549         match stmt.kind {
 550             // Expression without semicolon.
 551             StmtKind::Expr(ref mut expr)
 552                 if self.token != token::Eof && classify::expr_requires_semi_to_be_stmt(expr) =>
 553             {
 554                 // Just check for errors and recover; do not eat semicolon yet.
 555                 if let Err(mut e) =
 556                     self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
 557                 {
 558                     if let TokenKind::DocComment(..) = self.token.kind {
 559                         if let Ok(snippet) = self.span_to_snippet(self.token.span) {
 560                             let sp = self.token.span;
 561                             let marker = &snippet[..3];
 562                             let (comment_marker, doc_comment_marker) = marker.split_at(2);
 563
 564                             e.span_suggestion(
 565                                 sp.with_hi(sp.lo() + BytePos(marker.len() as u32)),
 566                                 &format!(
 567                                     "add a space before `{}` to use a regular comment",
 568                                     doc_comment_marker,
 569                                 ),
 570                                 format!("{} {}", comment_marker, doc_comment_marker),
 571                                 Applicability::MaybeIncorrect,
 572                             );
 573                         }
 574                     }
 575                     if let Err(mut e) =
 576                         self.check_mistyped_turbofish_with_multiple_type_params(e, expr)
 577                     {
 578                         if recover.no() {
 579                             return Err(e);
 580                         }
 581                         e.emit();
 582                         self.recover_stmt();
 583                     }
 584                     // Don't complain about type errors in body tail after parse error (#57383).
 585                     let sp = expr.span.to(self.prev_token.span);
 586                     *expr = self.mk_expr_err(sp);
 587                 }
 588             }
 589             StmtKind::Expr(_) | StmtKind::MacCall(_) => {}
 590             StmtKind::Local(ref mut local) if let Err(e) = self.expect_semi() => {
 591                 // We might be at the `,` in `let x = foo<bar, baz>;`. Try to recover.
 592                 match &mut local.kind {
 593                     LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => {
 594                         self.check_mistyped_turbofish_with_multiple_type_params(e, expr)?;
 595                         // We found `foo<bar, baz>`, have we fully recovered?
 596                         self.expect_semi()?;
 597                     }
 598                     LocalKind::Decl => return Err(e),
 599                 }
 600                 eat_semi = false;
 601             }
 602             StmtKind::Empty | StmtKind::Item(_) | StmtKind::Local(_) | StmtKind::Semi(_) => eat_semi = false,
 603         }
 604
 605         if eat_semi && self.eat(&token::Semi) {
 606             stmt = stmt.add_trailing_semicolon();
 607         }
 608         stmt.span = stmt.span.to(self.prev_token.span);
 609         Ok(Some(stmt))
 610     }
 611
 612     pub(super) fn mk_block(&self, stmts: Vec<Stmt>, rules: BlockCheckMode, span: Span) -> P<Block> {
 613         P(Block {
 614             stmts,
 615             id: DUMMY_NODE_ID,
 616             rules,
 617             span,
 618             tokens: None,
 619             could_be_bare_literal: false,
 620         })
 621     }
 622
 623     pub(super) fn mk_stmt(&self, span: Span, kind: StmtKind) -> Stmt {
 624         Stmt { id: DUMMY_NODE_ID, kind, span }
 625     }
 626
 627     pub(super) fn mk_stmt_err(&self, span: Span) -> Stmt {
 628         self.mk_stmt(span, StmtKind::Expr(self.mk_expr_err(span)))
 629     }
 630
 631     pub(super) fn mk_block_err(&self, span: Span) -> P<Block> {
 632         self.mk_block(vec![self.mk_stmt_err(span)], BlockCheckMode::Default, span)
 633     }
 634 }