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