compiler/rustc_parse/src/parser/stmt.rs

   1 use super::attr::InnerAttrForbiddenReason;
   2 use super::diagnostics::AttemptLocalParseRecovery;
   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::errors::{
  11     AssignmentElseNotAllowed, CompoundAssignmentExpressionInLet, ConstLetMutuallyExclusive,
  12     DocCommentDoesNotDocumentAnything, ExpectedStatementAfterOuterAttr, InvalidCurlyInLetElse,
  13     InvalidExpressionInLetElse, InvalidVariableDeclaration, InvalidVariableDeclarationSub,
  14     WrapExpressionInParentheses,
  15 };
  16 use crate::maybe_whole;
  17
  18 use rustc_ast as ast;
  19 use rustc_ast::ptr::P;
  20 use rustc_ast::token::{self, Delimiter, TokenKind};
  21 use rustc_ast::util::classify;
  22 use rustc_ast::{AttrStyle, AttrVec, LocalKind, MacCall, MacCallStmt, MacStmtStyle};
  23 use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, HasAttrs, Local, Stmt};
  24 use rustc_ast::{StmtKind, DUMMY_NODE_ID};
  25 use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult};
  26 use rustc_span::source_map::{BytePos, Span};
  27 use rustc_span::symbol::{kw, sym};
  28
  29 use std::mem;
  30
  31 impl<'a> Parser<'a> {
  32     /// Parses a statement. This stops just before trailing semicolons on everything but items.
  33     /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
  34     // Public for rustfmt usage.
  35     pub fn parse_stmt(&mut self, force_collect: ForceCollect) -> PResult<'a, Option<Stmt>> {
  36         Ok(self.parse_stmt_without_recovery(false, force_collect).unwrap_or_else(|mut e| {
  37             e.emit();
  38             self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
  39             None
  40         }))
  41     }
  42
  43     /// If `force_collect` is [`ForceCollect::Yes`], forces collection of tokens regardless of whether
  44     /// or not we have attributes
  45     pub(crate) fn parse_stmt_without_recovery(
  46         &mut self,
  47         capture_semi: bool,
  48         force_collect: ForceCollect,
  49     ) -> PResult<'a, Option<Stmt>> {
  50         let attrs = self.parse_outer_attributes()?;
  51         let lo = self.token.span;
  52
  53         // Don't use `maybe_whole` so that we have precise control
  54         // over when we bump the parser
  55         if let token::Interpolated(nt) = &self.token.kind && let token::NtStmt(stmt) = &**nt {
  56             let mut stmt = stmt.clone();
  57             self.bump();
  58             stmt.visit_attrs(|stmt_attrs| {
  59                 attrs.prepend_to_nt_inner(stmt_attrs);
  60             });
  61             return Ok(Some(stmt.into_inner()));
  62         }
  63
  64         if self.token.is_keyword(kw::Mut) && self.is_keyword_ahead(1, &[kw::Let]) {
  65             self.bump();
  66             let mut_let_span = lo.to(self.token.span);
  67             self.sess.emit_err(InvalidVariableDeclaration {
  68                 span: mut_let_span,
  69                 sub: InvalidVariableDeclarationSub::SwitchMutLetOrder(mut_let_span),
  70             });
  71         }
  72
  73         Ok(Some(if self.token.is_keyword(kw::Let) {
  74             self.parse_local_mk(lo, attrs, capture_semi, force_collect)?
  75         } else if self.is_kw_followed_by_ident(kw::Mut) {
  76             self.recover_stmt_local(lo, attrs, InvalidVariableDeclarationSub::MissingLet)?
  77         } else if self.is_kw_followed_by_ident(kw::Auto) {
  78             self.bump(); // `auto`
  79             self.recover_stmt_local(lo, attrs, InvalidVariableDeclarationSub::UseLetNotAuto)?
  80         } else if self.is_kw_followed_by_ident(sym::var) {
  81             self.bump(); // `var`
  82             self.recover_stmt_local(lo, attrs, InvalidVariableDeclarationSub::UseLetNotVar)?
  83         } else if self.check_path() && !self.token.is_qpath_start() && !self.is_path_start_item() {
  84             // We have avoided contextual keywords like `union`, items with `crate` visibility,
  85             // or `auto trait` items. We aim to parse an arbitrary path `a::b` but not something
  86             // that starts like a path (1 token), but it fact not a path.
  87             // Also, we avoid stealing syntax from `parse_item_`.
  88             if force_collect == ForceCollect::Yes {
  89                 self.collect_tokens_no_attrs(|this| this.parse_stmt_path_start(lo, attrs))
  90             } else {
  91                 self.parse_stmt_path_start(lo, attrs)
  92             }?
  93         } else if let Some(item) = self.parse_item_common(
  94             attrs.clone(),
  95             false,
  96             true,
  97             FnParseMode { req_name: |_| true, req_body: true },
  98             force_collect,
  99         )? {
 100             // FIXME: Bad copy of attrs
 101             self.mk_stmt(lo.to(item.span), StmtKind::Item(P(item)))
 102         } else if self.eat(&token::Semi) {
 103             // Do not attempt to parse an expression if we're done here.
 104             self.error_outer_attrs(attrs);
 105             self.mk_stmt(lo, StmtKind::Empty)
 106         } else if self.token != token::CloseDelim(Delimiter::Brace) {
 107             // Remainder are line-expr stmts.
 108             let e = if force_collect == ForceCollect::Yes {
 109                 self.collect_tokens_no_attrs(|this| {
 110                     this.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
 111                 })
 112             } else {
 113                 self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
 114             }?;
 115             if matches!(e.kind, ExprKind::Assign(..)) && self.eat_keyword(kw::Else) {
 116                 let bl = self.parse_block()?;
 117                 // Destructuring assignment ... else.
 118                 // This is not allowed, but point it out in a nice way.
 119                 self.sess.emit_err(AssignmentElseNotAllowed { span: e.span.to(bl.span) });
 120             }
 121             self.mk_stmt(lo.to(e.span), StmtKind::Expr(e))
 122         } else {
 123             self.error_outer_attrs(attrs);
 124             return Ok(None);
 125         }))
 126     }
 127
 128     fn parse_stmt_path_start(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> {
 129         let stmt = self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
 130             let path = this.parse_path(PathStyle::Expr)?;
 131
 132             if this.eat(&token::Not) {
 133                 let stmt_mac = this.parse_stmt_mac(lo, attrs, path)?;
 134                 if this.token == token::Semi {
 135                     return Ok((stmt_mac, TrailingToken::Semi));
 136                 } else {
 137                     return Ok((stmt_mac, TrailingToken::None));
 138                 }
 139             }
 140
 141             let expr = if this.eat(&token::OpenDelim(Delimiter::Brace)) {
 142                 this.parse_struct_expr(None, path, true)?
 143             } else {
 144                 let hi = this.prev_token.span;
 145                 this.mk_expr(lo.to(hi), ExprKind::Path(None, path))
 146             };
 147
 148             let expr = this.with_res(Restrictions::STMT_EXPR, |this| {
 149                 this.parse_dot_or_call_expr_with(expr, lo, attrs)
 150             })?;
 151             // `DUMMY_SP` will get overwritten later in this function
 152             Ok((this.mk_stmt(rustc_span::DUMMY_SP, StmtKind::Expr(expr)), TrailingToken::None))
 153         })?;
 154
 155         if let StmtKind::Expr(expr) = stmt.kind {
 156             // Perform this outside of the `collect_tokens_trailing_token` closure,
 157             // since our outer attributes do not apply to this part of the expression
 158             let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
 159                 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
 160             })?;
 161             Ok(self.mk_stmt(lo.to(self.prev_token.span), StmtKind::Expr(expr)))
 162         } else {
 163             Ok(stmt)
 164         }
 165     }
 166
 167     /// Parses a statement macro `mac!(args)` provided a `path` representing `mac`.
 168     /// At this point, the `!` token after the path has already been eaten.
 169     fn parse_stmt_mac(&mut self, lo: Span, attrs: AttrVec, path: ast::Path) -> PResult<'a, Stmt> {
 170         let args = self.parse_mac_args()?;
 171         let delim = args.delim();
 172         let hi = self.prev_token.span;
 173
 174         let style = match delim {
 175             Some(Delimiter::Brace) => MacStmtStyle::Braces,
 176             Some(_) => MacStmtStyle::NoBraces,
 177             None => unreachable!(),
 178         };
 179
 180         let mac = P(MacCall { path, args, prior_type_ascription: self.last_type_ascription });
 181
 182         let kind = if (style == MacStmtStyle::Braces
 183             && self.token != token::Dot
 184             && self.token != token::Question)
 185             || self.token == token::Semi
 186             || self.token == token::Eof
 187         {
 188             StmtKind::MacCall(P(MacCallStmt { mac, style, attrs, tokens: None }))
 189         } else {
 190             // Since none of the above applied, this is an expression statement macro.
 191             let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac));
 192             let e = self.maybe_recover_from_bad_qpath(e)?;
 193             let e = self.parse_dot_or_call_expr_with(e, lo, attrs)?;
 194             let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
 195             StmtKind::Expr(e)
 196         };
 197         Ok(self.mk_stmt(lo.to(hi), kind))
 198     }
 199
 200     /// Error on outer attributes in this context.
 201     /// Also error if the previous token was a doc comment.
 202     fn error_outer_attrs(&self, attrs: AttrWrapper) {
 203         if !attrs.is_empty()
 204         && let attrs = attrs.take_for_recovery(self.sess)
 205         && let attrs @ [.., last] = &*attrs {
 206             if last.is_doc_comment() {
 207                 self.sess.emit_err(DocCommentDoesNotDocumentAnything {
 208                     span: last.span,
 209                     missing_comma: None,
 210                 });
 211             } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
 212                 self.sess.emit_err(ExpectedStatementAfterOuterAttr { span: last.span });
 213             }
 214         }
 215     }
 216
 217     fn recover_stmt_local(
 218         &mut self,
 219         lo: Span,
 220         attrs: AttrWrapper,
 221         subdiagnostic: fn(Span) -> InvalidVariableDeclarationSub,
 222     ) -> PResult<'a, Stmt> {
 223         let stmt = self.recover_local_after_let(lo, attrs)?;
 224         self.sess.emit_err(InvalidVariableDeclaration { span: lo, sub: subdiagnostic(lo) });
 225         Ok(stmt)
 226     }
 227
 228     fn parse_local_mk(
 229         &mut self,
 230         lo: Span,
 231         attrs: AttrWrapper,
 232         capture_semi: bool,
 233         force_collect: ForceCollect,
 234     ) -> PResult<'a, Stmt> {
 235         self.collect_tokens_trailing_token(attrs, force_collect, |this, attrs| {
 236             this.expect_keyword(kw::Let)?;
 237             let local = this.parse_local(attrs)?;
 238             let trailing = if capture_semi && this.token.kind == token::Semi {
 239                 TrailingToken::Semi
 240             } else {
 241                 TrailingToken::None
 242             };
 243             Ok((this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)), trailing))
 244         })
 245     }
 246
 247     fn recover_local_after_let(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> {
 248         self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
 249             let local = this.parse_local(attrs)?;
 250             // FIXME - maybe capture semicolon in recovery?
 251             Ok((
 252                 this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)),
 253                 TrailingToken::None,
 254             ))
 255         })
 256     }
 257
 258     /// Parses a local variable declaration.
 259     fn parse_local(&mut self, attrs: AttrVec) -> PResult<'a, P<Local>> {
 260         let lo = self.prev_token.span;
 261
 262         if self.token.is_keyword(kw::Const) && self.look_ahead(1, |t| t.is_ident()) {
 263             self.sess.emit_err(ConstLetMutuallyExclusive { span: lo.to(self.token.span) });
 264             self.bump();
 265         }
 266
 267         let (pat, colon) = self.parse_pat_before_ty(None, RecoverComma::Yes, "`let` bindings")?;
 268
 269         let (err, ty) = if colon {
 270             // Save the state of the parser before parsing type normally, in case there is a `:`
 271             // instead of an `=` typo.
 272             let parser_snapshot_before_type = self.clone();
 273             let colon_sp = self.prev_token.span;
 274             match self.parse_ty() {
 275                 Ok(ty) => (None, Some(ty)),
 276                 Err(mut err) => {
 277                     if let Ok(snip) = self.span_to_snippet(pat.span) {
 278                         err.span_label(pat.span, format!("while parsing the type for `{}`", snip));
 279                     }
 280                     // we use noexpect here because we don't actually expect Eq to be here
 281                     // but we are still checking for it in order to be able to handle it if
 282                     // it is there
 283                     let err = if self.check_noexpect(&token::Eq) {
 284                         err.emit();
 285                         None
 286                     } else {
 287                         // Rewind to before attempting to parse the type and continue parsing.
 288                         let parser_snapshot_after_type =
 289                             mem::replace(self, parser_snapshot_before_type);
 290                         Some((parser_snapshot_after_type, colon_sp, err))
 291                     };
 292                     (err, None)
 293                 }
 294             }
 295         } else {
 296             (None, None)
 297         };
 298         let init = match (self.parse_initializer(err.is_some()), err) {
 299             (Ok(init), None) => {
 300                 // init parsed, ty parsed
 301                 init
 302             }
 303             (Ok(init), Some((_, colon_sp, mut err))) => {
 304                 // init parsed, ty error
 305                 // Could parse the type as if it were the initializer, it is likely there was a
 306                 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
 307                 err.span_suggestion_short(
 308                     colon_sp,
 309                     "use `=` if you meant to assign",
 310                     " =",
 311                     Applicability::MachineApplicable,
 312                 );
 313                 err.emit();
 314                 // As this was parsed successfully, continue as if the code has been fixed for the
 315                 // rest of the file. It will still fail due to the emitted error, but we avoid
 316                 // extra noise.
 317                 init
 318             }
 319             (Err(init_err), Some((snapshot, _, ty_err))) => {
 320                 // init error, ty error
 321                 init_err.cancel();
 322                 // Couldn't parse the type nor the initializer, only raise the type error and
 323                 // return to the parser state before parsing the type as the initializer.
 324                 // let x: <parse_error>;
 325                 *self = snapshot;
 326                 return Err(ty_err);
 327             }
 328             (Err(err), None) => {
 329                 // init error, ty parsed
 330                 // Couldn't parse the initializer and we're not attempting to recover a failed
 331                 // parse of the type, return the error.
 332                 return Err(err);
 333             }
 334         };
 335         let kind = match init {
 336             None => LocalKind::Decl,
 337             Some(init) => {
 338                 if self.eat_keyword(kw::Else) {
 339                     if self.token.is_keyword(kw::If) {
 340                         // `let...else if`. Emit the same error that `parse_block()` would,
 341                         // but explicitly point out that this pattern is not allowed.
 342                         let msg = "conditional `else if` is not supported for `let...else`";
 343                         return Err(self.error_block_no_opening_brace_msg(msg));
 344                     }
 345                     let els = self.parse_block()?;
 346                     self.check_let_else_init_bool_expr(&init);
 347                     self.check_let_else_init_trailing_brace(&init);
 348                     LocalKind::InitElse(init, els)
 349                 } else {
 350                     LocalKind::Init(init)
 351                 }
 352             }
 353         };
 354         let hi = if self.token == token::Semi { self.token.span } else { self.prev_token.span };
 355         Ok(P(ast::Local { ty, pat, kind, id: DUMMY_NODE_ID, span: lo.to(hi), attrs, tokens: None }))
 356     }
 357
 358     fn check_let_else_init_bool_expr(&self, init: &ast::Expr) {
 359         if let ast::ExprKind::Binary(op, ..) = init.kind {
 360             if op.node.lazy() {
 361                 self.sess.emit_err(InvalidExpressionInLetElse {
 362                     span: init.span,
 363                     operator: op.node.to_string(),
 364                     sugg: WrapExpressionInParentheses {
 365                         left: init.span.shrink_to_lo(),
 366                         right: init.span.shrink_to_hi(),
 367                     },
 368                 });
 369             }
 370         }
 371     }
 372
 373     fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) {
 374         if let Some(trailing) = classify::expr_trailing_brace(init) {
 375             self.sess.emit_err(InvalidCurlyInLetElse {
 376                 span: trailing.span.with_lo(trailing.span.hi() - BytePos(1)),
 377                 sugg: WrapExpressionInParentheses {
 378                     left: trailing.span.shrink_to_lo(),
 379                     right: trailing.span.shrink_to_hi(),
 380                 },
 381             });
 382         }
 383     }
 384
 385     /// Parses the RHS of a local variable declaration (e.g., `= 14;`).
 386     fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<P<Expr>>> {
 387         let eq_consumed = match self.token.kind {
 388             token::BinOpEq(..) => {
 389                 // Recover `let x <op>= 1` as `let x = 1`
 390                 self.sess.emit_err(CompoundAssignmentExpressionInLet { span: self.token.span });
 391                 self.bump();
 392                 true
 393             }
 394             _ => self.eat(&token::Eq),
 395         };
 396
 397         Ok(if eq_consumed || eq_optional { Some(self.parse_expr()?) } else { None })
 398     }
 399
 400     /// Parses a block. No inner attributes are allowed.
 401     pub(super) fn parse_block(&mut self) -> PResult<'a, P<Block>> {
 402         let (attrs, block) = self.parse_inner_attrs_and_block()?;
 403         if let [.., last] = &*attrs {
 404             self.error_on_forbidden_inner_attr(
 405                 last.span,
 406                 super::attr::InnerAttrPolicy::Forbidden(Some(
 407                     InnerAttrForbiddenReason::InCodeBlock,
 408                 )),
 409             );
 410         }
 411         Ok(block)
 412     }
 413
 414     fn error_block_no_opening_brace_msg(
 415         &mut self,
 416         msg: &str,
 417     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
 418         let sp = self.token.span;
 419         let mut e = self.struct_span_err(sp, msg);
 420         let do_not_suggest_help = self.token.is_keyword(kw::In) || self.token == token::Colon;
 421
 422         // Check to see if the user has written something like
 423         //
 424         //    if (cond)
 425         //      bar;
 426         //
 427         // which is valid in other languages, but not Rust.
 428         match self.parse_stmt_without_recovery(false, ForceCollect::No) {
 429             // If the next token is an open brace, e.g., we have:
 430             //
 431             //     if expr other_expr {
 432             //        ^    ^          ^- lookahead(1) is a brace
 433             //        |    |- current token is not "else"
 434             //        |- (statement we just parsed)
 435             //
 436             // the place-inside-a-block suggestion would be more likely wrong than right.
 437             //
 438             // FIXME(compiler-errors): this should probably parse an arbitrary expr and not
 439             // just lookahead one token, so we can see if there's a brace after _that_,
 440             // since we want to protect against:
 441             //     `if 1 1 + 1 {` being suggested as  `if { 1 } 1 + 1 {`
 442             //                                            +   +
 443             Ok(Some(_))
 444                 if (!self.token.is_keyword(kw::Else)
 445                     && self.look_ahead(1, |t| t == &token::OpenDelim(Delimiter::Brace)))
 446                     || do_not_suggest_help => {}
 447             // Do not suggest `if foo println!("") {;}` (as would be seen in test for #46836).
 448             Ok(Some(Stmt { kind: StmtKind::Empty, .. })) => {}
 449             Ok(Some(stmt)) => {
 450                 let stmt_own_line = self.sess.source_map().is_line_before_span_empty(sp);
 451                 let stmt_span = if stmt_own_line && self.eat(&token::Semi) {
 452                     // Expand the span to include the semicolon.
 453                     stmt.span.with_hi(self.prev_token.span.hi())
 454                 } else {
 455                     stmt.span
 456                 };
 457                 e.multipart_suggestion(
 458                     "try placing this code inside a block",
 459                     vec![
 460                         (stmt_span.shrink_to_lo(), "{ ".to_string()),
 461                         (stmt_span.shrink_to_hi(), " }".to_string()),
 462                     ],
 463                     // Speculative; has been misleading in the past (#46836).
 464                     Applicability::MaybeIncorrect,
 465                 );
 466             }
 467             Err(e) => {
 468                 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
 469                 e.cancel();
 470             }
 471             _ => {}
 472         }
 473         e.span_label(sp, "expected `{`");
 474         e
 475     }
 476
 477     fn error_block_no_opening_brace<T>(&mut self) -> PResult<'a, T> {
 478         let tok = super::token_descr(&self.token);
 479         let msg = format!("expected `{{`, found {}", tok);
 480         Err(self.error_block_no_opening_brace_msg(&msg))
 481     }
 482
 483     /// Parses a block. Inner attributes are allowed.
 484     pub(super) fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (AttrVec, P<Block>)> {
 485         self.parse_block_common(self.token.span, BlockCheckMode::Default)
 486     }
 487
 488     /// Parses a block. Inner attributes are allowed.
 489     pub(super) fn parse_block_common(
 490         &mut self,
 491         lo: Span,
 492         blk_mode: BlockCheckMode,
 493     ) -> PResult<'a, (AttrVec, P<Block>)> {
 494         maybe_whole!(self, NtBlock, |x| (AttrVec::new(), x));
 495
 496         self.maybe_recover_unexpected_block_label();
 497         if !self.eat(&token::OpenDelim(Delimiter::Brace)) {
 498             return self.error_block_no_opening_brace();
 499         }
 500
 501         let attrs = self.parse_inner_attributes()?;
 502         let tail = match self.maybe_suggest_struct_literal(lo, blk_mode) {
 503             Some(tail) => tail?,
 504             None => self.parse_block_tail(lo, blk_mode, AttemptLocalParseRecovery::Yes)?,
 505         };
 506         Ok((attrs, tail))
 507     }
 508
 509     /// Parses the rest of a block expression or function body.
 510     /// Precondition: already parsed the '{'.
 511     pub(crate) fn parse_block_tail(
 512         &mut self,
 513         lo: Span,
 514         s: BlockCheckMode,
 515         recover: AttemptLocalParseRecovery,
 516     ) -> PResult<'a, P<Block>> {
 517         let mut stmts = vec![];
 518         while !self.eat(&token::CloseDelim(Delimiter::Brace)) {
 519             if self.token == token::Eof {
 520                 break;
 521             }
 522             let stmt = match self.parse_full_stmt(recover) {
 523                 Err(mut err) if recover.yes() => {
 524                     self.maybe_annotate_with_ascription(&mut err, false);
 525                     err.emit();
 526                     self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
 527                     Some(self.mk_stmt_err(self.token.span))
 528                 }
 529                 Ok(stmt) => stmt,
 530                 Err(err) => return Err(err),
 531             };
 532             if let Some(stmt) = stmt {
 533                 stmts.push(stmt);
 534             } else {
 535                 // Found only `;` or `}`.
 536                 continue;
 537             };
 538         }
 539         Ok(self.mk_block(stmts, s, lo.to(self.prev_token.span)))
 540     }
 541
 542     /// Parses a statement, including the trailing semicolon.
 543     pub fn parse_full_stmt(
 544         &mut self,
 545         recover: AttemptLocalParseRecovery,
 546     ) -> PResult<'a, Option<Stmt>> {
 547         // Skip looking for a trailing semicolon when we have an interpolated statement.
 548         maybe_whole!(self, NtStmt, |x| Some(x.into_inner()));
 549
 550         let Some(mut stmt) = self.parse_stmt_without_recovery(true, ForceCollect::No)? else {
 551             return Ok(None);
 552         };
 553
 554         let mut eat_semi = true;
 555         match stmt.kind {
 556             // Expression without semicolon.
 557             StmtKind::Expr(ref mut expr)
 558                 if self.token != token::Eof && classify::expr_requires_semi_to_be_stmt(expr) => {
 559                 // Just check for errors and recover; do not eat semicolon yet.
 560                 // `expect_one_of` returns PResult<'a, bool /* recovered */>
 561                 let replace_with_err =
 562                     match self.expect_one_of(&[], &[token::Semi, token::CloseDelim(Delimiter::Brace)]) {
 563                     // Recover from parser, skip type error to avoid extra errors.
 564                     Ok(true) => true,
 565                     Err(mut e) => {
 566                         if let TokenKind::DocComment(..) = self.token.kind &&
 567                             let Ok(snippet) = self.span_to_snippet(self.token.span) {
 568                                 let sp = self.token.span;
 569                                 let marker = &snippet[..3];
 570                                 let (comment_marker, doc_comment_marker) = marker.split_at(2);
 571
 572                                 e.span_suggestion(
 573                                     sp.with_hi(sp.lo() + BytePos(marker.len() as u32)),
 574                                     &format!(
 575                                         "add a space before `{}` to use a regular comment",
 576                                         doc_comment_marker,
 577                                     ),
 578                                     format!("{} {}", comment_marker, doc_comment_marker),
 579                                     Applicability::MaybeIncorrect,
 580                                 );
 581                         }
 582
 583                         if let Err(mut e) =
 584                             self.check_mistyped_turbofish_with_multiple_type_params(e, expr)
 585                         {
 586                             if recover.no() {
 587                                 return Err(e);
 588                             }
 589                             e.emit();
 590                             self.recover_stmt();
 591                         }
 592                         true
 593                     }
 594                     _ => false
 595                 };
 596                 if replace_with_err {
 597                     // We already emitted an error, so don't emit another type error
 598                     let sp = expr.span.to(self.prev_token.span);
 599                     *expr = self.mk_expr_err(sp);
 600                 }
 601             }
 602             StmtKind::Expr(_) | StmtKind::MacCall(_) => {}
 603             StmtKind::Local(ref mut local) if let Err(e) = self.expect_semi() => {
 604                 // We might be at the `,` in `let x = foo<bar, baz>;`. Try to recover.
 605                 match &mut local.kind {
 606                     LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => {
 607                         self.check_mistyped_turbofish_with_multiple_type_params(e, expr)?;
 608                         // We found `foo<bar, baz>`, have we fully recovered?
 609                         self.expect_semi()?;
 610                     }
 611                     LocalKind::Decl => return Err(e),
 612                 }
 613                 eat_semi = false;
 614             }
 615             StmtKind::Empty | StmtKind::Item(_) | StmtKind::Local(_) | StmtKind::Semi(_) => eat_semi = false,
 616         }
 617
 618         if eat_semi && self.eat(&token::Semi) {
 619             stmt = stmt.add_trailing_semicolon();
 620         }
 621         stmt.span = stmt.span.to(self.prev_token.span);
 622         Ok(Some(stmt))
 623     }
 624
 625     pub(super) fn mk_block(&self, stmts: Vec<Stmt>, rules: BlockCheckMode, span: Span) -> P<Block> {
 626         P(Block {
 627             stmts,
 628             id: DUMMY_NODE_ID,
 629             rules,
 630             span,
 631             tokens: None,
 632             could_be_bare_literal: false,
 633         })
 634     }
 635
 636     pub(super) fn mk_stmt(&self, span: Span, kind: StmtKind) -> Stmt {
 637         Stmt { id: DUMMY_NODE_ID, kind, span }
 638     }
 639
 640     pub(super) fn mk_stmt_err(&self, span: Span) -> Stmt {
 641         self.mk_stmt(span, StmtKind::Expr(self.mk_expr_err(span)))
 642     }
 643
 644     pub(super) fn mk_block_err(&self, span: Span) -> P<Block> {
 645         self.mk_block(vec![self.mk_stmt_err(span)], BlockCheckMode::Default, span)
 646     }
 647 }