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, InvalidIdentiferStartsWithNumber, InvalidVariableDeclaration,
  14     InvalidVariableDeclarationSub, 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) && self.may_recover() {
  76             self.recover_stmt_local_after_let(lo, attrs, InvalidVariableDeclarationSub::MissingLet)?
  77         } else if self.is_kw_followed_by_ident(kw::Auto) && self.may_recover() {
  78             self.bump(); // `auto`
  79             self.recover_stmt_local_after_let(
  80                 lo,
  81                 attrs,
  82                 InvalidVariableDeclarationSub::UseLetNotAuto,
  83             )?
  84         } else if self.is_kw_followed_by_ident(sym::var) && self.may_recover() {
  85             self.bump(); // `var`
  86             self.recover_stmt_local_after_let(
  87                 lo,
  88                 attrs,
  89                 InvalidVariableDeclarationSub::UseLetNotVar,
  90             )?
  91         } else if self.check_path() && !self.token.is_qpath_start() && !self.is_path_start_item() {
  92             // We have avoided contextual keywords like `union`, items with `crate` visibility,
  93             // or `auto trait` items. We aim to parse an arbitrary path `a::b` but not something
  94             // that starts like a path (1 token), but it fact not a path.
  95             // Also, we avoid stealing syntax from `parse_item_`.
  96             if force_collect == ForceCollect::Yes {
  97                 self.collect_tokens_no_attrs(|this| this.parse_stmt_path_start(lo, attrs))
  98             } else {
  99                 self.parse_stmt_path_start(lo, attrs)
 100             }?
 101         } else if let Some(item) = self.parse_item_common(
 102             attrs.clone(),
 103             false,
 104             true,
 105             FnParseMode { req_name: |_| true, req_body: true },
 106             force_collect,
 107         )? {
 108             // FIXME: Bad copy of attrs
 109             self.mk_stmt(lo.to(item.span), StmtKind::Item(P(item)))
 110         } else if self.eat(&token::Semi) {
 111             // Do not attempt to parse an expression if we're done here.
 112             self.error_outer_attrs(attrs);
 113             self.mk_stmt(lo, StmtKind::Empty)
 114         } else if self.token != token::CloseDelim(Delimiter::Brace) {
 115             // Remainder are line-expr stmts.
 116             let e = if force_collect == ForceCollect::Yes {
 117                 self.collect_tokens_no_attrs(|this| {
 118                     this.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
 119                 })
 120             } else {
 121                 self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
 122             }?;
 123             if matches!(e.kind, ExprKind::Assign(..)) && self.eat_keyword(kw::Else) {
 124                 let bl = self.parse_block()?;
 125                 // Destructuring assignment ... else.
 126                 // This is not allowed, but point it out in a nice way.
 127                 self.sess.emit_err(AssignmentElseNotAllowed { span: e.span.to(bl.span) });
 128             }
 129             self.mk_stmt(lo.to(e.span), StmtKind::Expr(e))
 130         } else {
 131             self.error_outer_attrs(attrs);
 132             return Ok(None);
 133         }))
 134     }
 135
 136     fn parse_stmt_path_start(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> {
 137         let stmt = self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
 138             let path = this.parse_path(PathStyle::Expr)?;
 139
 140             if this.eat(&token::Not) {
 141                 let stmt_mac = this.parse_stmt_mac(lo, attrs, path)?;
 142                 if this.token == token::Semi {
 143                     return Ok((stmt_mac, TrailingToken::Semi));
 144                 } else {
 145                     return Ok((stmt_mac, TrailingToken::None));
 146                 }
 147             }
 148
 149             let expr = if this.eat(&token::OpenDelim(Delimiter::Brace)) {
 150                 this.parse_struct_expr(None, path, true)?
 151             } else {
 152                 let hi = this.prev_token.span;
 153                 this.mk_expr(lo.to(hi), ExprKind::Path(None, path))
 154             };
 155
 156             let expr = this.with_res(Restrictions::STMT_EXPR, |this| {
 157                 this.parse_dot_or_call_expr_with(expr, lo, attrs)
 158             })?;
 159             // `DUMMY_SP` will get overwritten later in this function
 160             Ok((this.mk_stmt(rustc_span::DUMMY_SP, StmtKind::Expr(expr)), TrailingToken::None))
 161         })?;
 162
 163         if let StmtKind::Expr(expr) = stmt.kind {
 164             // Perform this outside of the `collect_tokens_trailing_token` closure,
 165             // since our outer attributes do not apply to this part of the expression
 166             let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
 167                 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr, true))
 168             })?;
 169             Ok(self.mk_stmt(lo.to(self.prev_token.span), StmtKind::Expr(expr)))
 170         } else {
 171             Ok(stmt)
 172         }
 173     }
 174
 175     /// Parses a statement macro `mac!(args)` provided a `path` representing `mac`.
 176     /// At this point, the `!` token after the path has already been eaten.
 177     fn parse_stmt_mac(&mut self, lo: Span, attrs: AttrVec, path: ast::Path) -> PResult<'a, Stmt> {
 178         let args = self.parse_delim_args()?;
 179         let delim = args.delim.to_token();
 180         let hi = self.prev_token.span;
 181
 182         let style = match delim {
 183             Delimiter::Brace => MacStmtStyle::Braces,
 184             _ => MacStmtStyle::NoBraces,
 185         };
 186
 187         let mac = P(MacCall { path, args, prior_type_ascription: self.last_type_ascription });
 188
 189         let kind = if (style == MacStmtStyle::Braces
 190             && self.token != token::Dot
 191             && self.token != token::Question)
 192             || self.token == token::Semi
 193             || self.token == token::Eof
 194         {
 195             StmtKind::MacCall(P(MacCallStmt { mac, style, attrs, tokens: None }))
 196         } else {
 197             // Since none of the above applied, this is an expression statement macro.
 198             let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac));
 199             let e = self.maybe_recover_from_bad_qpath(e)?;
 200             let e = self.parse_dot_or_call_expr_with(e, lo, attrs)?;
 201             let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e, false))?;
 202             StmtKind::Expr(e)
 203         };
 204         Ok(self.mk_stmt(lo.to(hi), kind))
 205     }
 206
 207     /// Error on outer attributes in this context.
 208     /// Also error if the previous token was a doc comment.
 209     fn error_outer_attrs(&self, attrs: AttrWrapper) {
 210         if !attrs.is_empty()
 211         && let attrs = attrs.take_for_recovery(self.sess)
 212         && let attrs @ [.., last] = &*attrs {
 213             if last.is_doc_comment() {
 214                 self.sess.emit_err(DocCommentDoesNotDocumentAnything {
 215                     span: last.span,
 216                     missing_comma: None,
 217                 });
 218             } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
 219                 self.sess.emit_err(ExpectedStatementAfterOuterAttr { span: last.span });
 220             }
 221         }
 222     }
 223
 224     fn recover_stmt_local_after_let(
 225         &mut self,
 226         lo: Span,
 227         attrs: AttrWrapper,
 228         subdiagnostic: fn(Span) -> InvalidVariableDeclarationSub,
 229     ) -> PResult<'a, Stmt> {
 230         let stmt =
 231             self.collect_tokens_trailing_token(attrs, ForceCollect::Yes, |this, attrs| {
 232                 let local = this.parse_local(attrs)?;
 233                 // FIXME - maybe capture semicolon in recovery?
 234                 Ok((
 235                     this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)),
 236                     TrailingToken::None,
 237                 ))
 238             })?;
 239         self.sess.emit_err(InvalidVariableDeclaration { span: lo, sub: subdiagnostic(lo) });
 240         Ok(stmt)
 241     }
 242
 243     fn parse_local_mk(
 244         &mut self,
 245         lo: Span,
 246         attrs: AttrWrapper,
 247         capture_semi: bool,
 248         force_collect: ForceCollect,
 249     ) -> PResult<'a, Stmt> {
 250         self.collect_tokens_trailing_token(attrs, force_collect, |this, attrs| {
 251             this.expect_keyword(kw::Let)?;
 252             let local = this.parse_local(attrs)?;
 253             let trailing = if capture_semi && this.token.kind == token::Semi {
 254                 TrailingToken::Semi
 255             } else {
 256                 TrailingToken::None
 257             };
 258             Ok((this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)), trailing))
 259         })
 260     }
 261
 262     /// Parses a local variable declaration.
 263     fn parse_local(&mut self, attrs: AttrVec) -> PResult<'a, P<Local>> {
 264         let lo = self.prev_token.span;
 265
 266         if self.token.is_keyword(kw::Const) && self.look_ahead(1, |t| t.is_ident()) {
 267             self.sess.emit_err(ConstLetMutuallyExclusive { span: lo.to(self.token.span) });
 268             self.bump();
 269         }
 270
 271         self.report_invalid_identifier_error()?;
 272         let (pat, colon) = self.parse_pat_before_ty(None, RecoverComma::Yes, "`let` bindings")?;
 273
 274         let (err, ty) = if colon {
 275             // Save the state of the parser before parsing type normally, in case there is a `:`
 276             // instead of an `=` typo.
 277             let parser_snapshot_before_type = self.clone();
 278             let colon_sp = self.prev_token.span;
 279             match self.parse_ty() {
 280                 Ok(ty) => (None, Some(ty)),
 281                 Err(mut err) => {
 282                     if let Ok(snip) = self.span_to_snippet(pat.span) {
 283                         err.span_label(pat.span, format!("while parsing the type for `{}`", snip));
 284                     }
 285                     // we use noexpect here because we don't actually expect Eq to be here
 286                     // but we are still checking for it in order to be able to handle it if
 287                     // it is there
 288                     let err = if self.check_noexpect(&token::Eq) {
 289                         err.emit();
 290                         None
 291                     } else {
 292                         // Rewind to before attempting to parse the type and continue parsing.
 293                         let parser_snapshot_after_type =
 294                             mem::replace(self, parser_snapshot_before_type);
 295                         Some((parser_snapshot_after_type, colon_sp, err))
 296                     };
 297                     (err, None)
 298                 }
 299             }
 300         } else {
 301             (None, None)
 302         };
 303         let init = match (self.parse_initializer(err.is_some()), err) {
 304             (Ok(init), None) => {
 305                 // init parsed, ty parsed
 306                 init
 307             }
 308             (Ok(init), Some((_, colon_sp, mut err))) => {
 309                 // init parsed, ty error
 310                 // Could parse the type as if it were the initializer, it is likely there was a
 311                 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
 312                 err.span_suggestion_short(
 313                     colon_sp,
 314                     "use `=` if you meant to assign",
 315                     " =",
 316                     Applicability::MachineApplicable,
 317                 );
 318                 err.emit();
 319                 // As this was parsed successfully, continue as if the code has been fixed for the
 320                 // rest of the file. It will still fail due to the emitted error, but we avoid
 321                 // extra noise.
 322                 init
 323             }
 324             (Err(init_err), Some((snapshot, _, ty_err))) => {
 325                 // init error, ty error
 326                 init_err.cancel();
 327                 // Couldn't parse the type nor the initializer, only raise the type error and
 328                 // return to the parser state before parsing the type as the initializer.
 329                 // let x: <parse_error>;
 330                 *self = snapshot;
 331                 return Err(ty_err);
 332             }
 333             (Err(err), None) => {
 334                 // init error, ty parsed
 335                 // Couldn't parse the initializer and we're not attempting to recover a failed
 336                 // parse of the type, return the error.
 337                 return Err(err);
 338             }
 339         };
 340         let kind = match init {
 341             None => LocalKind::Decl,
 342             Some(init) => {
 343                 if self.eat_keyword(kw::Else) {
 344                     if self.token.is_keyword(kw::If) {
 345                         // `let...else if`. Emit the same error that `parse_block()` would,
 346                         // but explicitly point out that this pattern is not allowed.
 347                         let msg = "conditional `else if` is not supported for `let...else`";
 348                         return Err(self.error_block_no_opening_brace_msg(msg));
 349                     }
 350                     let els = self.parse_block()?;
 351                     self.check_let_else_init_bool_expr(&init);
 352                     self.check_let_else_init_trailing_brace(&init);
 353                     LocalKind::InitElse(init, els)
 354                 } else {
 355                     LocalKind::Init(init)
 356                 }
 357             }
 358         };
 359         let hi = if self.token == token::Semi { self.token.span } else { self.prev_token.span };
 360         Ok(P(ast::Local { ty, pat, kind, id: DUMMY_NODE_ID, span: lo.to(hi), attrs, tokens: None }))
 361     }
 362
 363     /// report error for `let 1x = 123`
 364     pub fn report_invalid_identifier_error(&mut self) -> PResult<'a, ()> {
 365         if let token::Literal(lit) = self.token.uninterpolate().kind &&
 366             rustc_ast::MetaItemLit::from_token(&self.token).is_none() &&
 367             (lit.kind == token::LitKind::Integer || lit.kind == token::LitKind::Float) &&
 368             self.look_ahead(1, |t| matches!(t.kind, token::Eq) || matches!(t.kind, token::Colon ) ) {
 369                 return Err(self.sess.create_err(InvalidIdentiferStartsWithNumber { span: self.token.span }));
 370         }
 371         Ok(())
 372     }
 373
 374     fn check_let_else_init_bool_expr(&self, init: &ast::Expr) {
 375         if let ast::ExprKind::Binary(op, ..) = init.kind {
 376             if op.node.lazy() {
 377                 self.sess.emit_err(InvalidExpressionInLetElse {
 378                     span: init.span,
 379                     operator: op.node.to_string(),
 380                     sugg: WrapExpressionInParentheses {
 381                         left: init.span.shrink_to_lo(),
 382                         right: init.span.shrink_to_hi(),
 383                     },
 384                 });
 385             }
 386         }
 387     }
 388
 389     fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) {
 390         if let Some(trailing) = classify::expr_trailing_brace(init) {
 391             self.sess.emit_err(InvalidCurlyInLetElse {
 392                 span: trailing.span.with_lo(trailing.span.hi() - BytePos(1)),
 393                 sugg: WrapExpressionInParentheses {
 394                     left: trailing.span.shrink_to_lo(),
 395                     right: trailing.span.shrink_to_hi(),
 396                 },
 397             });
 398         }
 399     }
 400
 401     /// Parses the RHS of a local variable declaration (e.g., `= 14;`).
 402     fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<P<Expr>>> {
 403         let eq_consumed = match self.token.kind {
 404             token::BinOpEq(..) => {
 405                 // Recover `let x <op>= 1` as `let x = 1`
 406                 self.sess.emit_err(CompoundAssignmentExpressionInLet { span: self.token.span });
 407                 self.bump();
 408                 true
 409             }
 410             _ => self.eat(&token::Eq),
 411         };
 412
 413         Ok(if eq_consumed || eq_optional { Some(self.parse_expr()?) } else { None })
 414     }
 415
 416     /// Parses a block. No inner attributes are allowed.
 417     pub(super) fn parse_block(&mut self) -> PResult<'a, P<Block>> {
 418         let (attrs, block) = self.parse_inner_attrs_and_block()?;
 419         if let [.., last] = &*attrs {
 420             self.error_on_forbidden_inner_attr(
 421                 last.span,
 422                 super::attr::InnerAttrPolicy::Forbidden(Some(
 423                     InnerAttrForbiddenReason::InCodeBlock,
 424                 )),
 425             );
 426         }
 427         Ok(block)
 428     }
 429
 430     fn error_block_no_opening_brace_msg(
 431         &mut self,
 432         msg: &str,
 433     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
 434         let sp = self.token.span;
 435         let mut e = self.struct_span_err(sp, msg);
 436         let do_not_suggest_help = self.token.is_keyword(kw::In) || self.token == token::Colon;
 437
 438         // Check to see if the user has written something like
 439         //
 440         //    if (cond)
 441         //      bar;
 442         //
 443         // which is valid in other languages, but not Rust.
 444         match self.parse_stmt_without_recovery(false, ForceCollect::No) {
 445             // If the next token is an open brace, e.g., we have:
 446             //
 447             //     if expr other_expr {
 448             //        ^    ^          ^- lookahead(1) is a brace
 449             //        |    |- current token is not "else"
 450             //        |- (statement we just parsed)
 451             //
 452             // the place-inside-a-block suggestion would be more likely wrong than right.
 453             //
 454             // FIXME(compiler-errors): this should probably parse an arbitrary expr and not
 455             // just lookahead one token, so we can see if there's a brace after _that_,
 456             // since we want to protect against:
 457             //     `if 1 1 + 1 {` being suggested as  `if { 1 } 1 + 1 {`
 458             //                                            +   +
 459             Ok(Some(_))
 460                 if (!self.token.is_keyword(kw::Else)
 461                     && self.look_ahead(1, |t| t == &token::OpenDelim(Delimiter::Brace)))
 462                     || do_not_suggest_help => {}
 463             // Do not suggest `if foo println!("") {;}` (as would be seen in test for #46836).
 464             Ok(Some(Stmt { kind: StmtKind::Empty, .. })) => {}
 465             Ok(Some(stmt)) => {
 466                 let stmt_own_line = self.sess.source_map().is_line_before_span_empty(sp);
 467                 let stmt_span = if stmt_own_line && self.eat(&token::Semi) {
 468                     // Expand the span to include the semicolon.
 469                     stmt.span.with_hi(self.prev_token.span.hi())
 470                 } else {
 471                     stmt.span
 472                 };
 473                 e.multipart_suggestion(
 474                     "try placing this code inside a block",
 475                     vec![
 476                         (stmt_span.shrink_to_lo(), "{ ".to_string()),
 477                         (stmt_span.shrink_to_hi(), " }".to_string()),
 478                     ],
 479                     // Speculative; has been misleading in the past (#46836).
 480                     Applicability::MaybeIncorrect,
 481                 );
 482             }
 483             Err(e) => {
 484                 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
 485                 e.cancel();
 486             }
 487             _ => {}
 488         }
 489         e.span_label(sp, "expected `{`");
 490         e
 491     }
 492
 493     fn error_block_no_opening_brace<T>(&mut self) -> PResult<'a, T> {
 494         let tok = super::token_descr(&self.token);
 495         let msg = format!("expected `{{`, found {}", tok);
 496         Err(self.error_block_no_opening_brace_msg(&msg))
 497     }
 498
 499     /// Parses a block. Inner attributes are allowed.
 500     pub(super) fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (AttrVec, P<Block>)> {
 501         self.parse_block_common(self.token.span, BlockCheckMode::Default, true)
 502     }
 503
 504     /// Parses a block. Inner attributes are allowed.
 505     pub(super) fn parse_block_common(
 506         &mut self,
 507         lo: Span,
 508         blk_mode: BlockCheckMode,
 509         can_be_struct_literal: bool,
 510     ) -> PResult<'a, (AttrVec, P<Block>)> {
 511         maybe_whole!(self, NtBlock, |x| (AttrVec::new(), x));
 512
 513         let maybe_ident = self.prev_token.clone();
 514         self.maybe_recover_unexpected_block_label();
 515         if !self.eat(&token::OpenDelim(Delimiter::Brace)) {
 516             return self.error_block_no_opening_brace();
 517         }
 518
 519         let attrs = self.parse_inner_attributes()?;
 520         let tail = match self.maybe_suggest_struct_literal(
 521             lo,
 522             blk_mode,
 523             maybe_ident,
 524             can_be_struct_literal,
 525         ) {
 526             Some(tail) => tail?,
 527             None => self.parse_block_tail(lo, blk_mode, AttemptLocalParseRecovery::Yes)?,
 528         };
 529         Ok((attrs, tail))
 530     }
 531
 532     /// Parses the rest of a block expression or function body.
 533     /// Precondition: already parsed the '{'.
 534     pub(crate) fn parse_block_tail(
 535         &mut self,
 536         lo: Span,
 537         s: BlockCheckMode,
 538         recover: AttemptLocalParseRecovery,
 539     ) -> PResult<'a, P<Block>> {
 540         let mut stmts = vec![];
 541         let mut snapshot = None;
 542         while !self.eat(&token::CloseDelim(Delimiter::Brace)) {
 543             if self.token == token::Eof {
 544                 break;
 545             }
 546             if self.is_diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
 547                 // Account for `<<<<<<<` diff markers. We can't proactively error here because
 548                 // that can be a valid path start, so we snapshot and reparse only we've
 549                 // encountered another parse error.
 550                 snapshot = Some(self.create_snapshot_for_diagnostic());
 551             }
 552             let stmt = match self.parse_full_stmt(recover) {
 553                 Err(mut err) if recover.yes() => {
 554                     self.maybe_annotate_with_ascription(&mut err, false);
 555                     if let Some(ref mut snapshot) = snapshot {
 556                         snapshot.recover_diff_marker();
 557                     }
 558                     err.emit();
 559                     self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
 560                     Some(self.mk_stmt_err(self.token.span))
 561                 }
 562                 Ok(stmt) => stmt,
 563                 Err(err) => return Err(err),
 564             };
 565             if let Some(stmt) = stmt {
 566                 stmts.push(stmt);
 567             } else {
 568                 // Found only `;` or `}`.
 569                 continue;
 570             };
 571         }
 572         Ok(self.mk_block(stmts, s, lo.to(self.prev_token.span)))
 573     }
 574
 575     /// Parses a statement, including the trailing semicolon.
 576     pub fn parse_full_stmt(
 577         &mut self,
 578         recover: AttemptLocalParseRecovery,
 579     ) -> PResult<'a, Option<Stmt>> {
 580         // Skip looking for a trailing semicolon when we have an interpolated statement.
 581         maybe_whole!(self, NtStmt, |x| Some(x.into_inner()));
 582
 583         let Some(mut stmt) = self.parse_stmt_without_recovery(true, ForceCollect::No)? else {
 584             return Ok(None);
 585         };
 586
 587         let mut eat_semi = true;
 588         match &mut stmt.kind {
 589             // Expression without semicolon.
 590             StmtKind::Expr(expr)
 591                 if self.token != token::Eof && classify::expr_requires_semi_to_be_stmt(expr) => {
 592                 // Just check for errors and recover; do not eat semicolon yet.
 593                 // `expect_one_of` returns PResult<'a, bool /* recovered */>
 594                 let replace_with_err =
 595                     match self.expect_one_of(&[], &[token::Semi, token::CloseDelim(Delimiter::Brace)]) {
 596                     // Recover from parser, skip type error to avoid extra errors.
 597                     Ok(true) => true,
 598                     Err(mut e) => {
 599                         if let TokenKind::DocComment(..) = self.token.kind &&
 600                             let Ok(snippet) = self.span_to_snippet(self.token.span) {
 601                                 let sp = self.token.span;
 602                                 let marker = &snippet[..3];
 603                                 let (comment_marker, doc_comment_marker) = marker.split_at(2);
 604
 605                                 e.span_suggestion(
 606                                     sp.with_hi(sp.lo() + BytePos(marker.len() as u32)),
 607                                     &format!(
 608                                         "add a space before `{}` to use a regular comment",
 609                                         doc_comment_marker,
 610                                     ),
 611                                     format!("{} {}", comment_marker, doc_comment_marker),
 612                                     Applicability::MaybeIncorrect,
 613                                 );
 614                         }
 615
 616                         if let Err(mut e) =
 617                             self.check_mistyped_turbofish_with_multiple_type_params(e, expr)
 618                         {
 619                             if recover.no() {
 620                                 return Err(e);
 621                             }
 622                             e.emit();
 623                             self.recover_stmt();
 624                         }
 625                         true
 626                     }
 627                     _ => false
 628                 };
 629                 if replace_with_err {
 630                     // We already emitted an error, so don't emit another type error
 631                     let sp = expr.span.to(self.prev_token.span);
 632                     *expr = self.mk_expr_err(sp);
 633                 }
 634             }
 635             StmtKind::Expr(_) | StmtKind::MacCall(_) => {}
 636             StmtKind::Local(local) if let Err(e) = self.expect_semi() => {
 637                 // We might be at the `,` in `let x = foo<bar, baz>;`. Try to recover.
 638                 match &mut local.kind {
 639                     LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => {
 640                         self.check_mistyped_turbofish_with_multiple_type_params(e, expr)?;
 641                         // We found `foo<bar, baz>`, have we fully recovered?
 642                         self.expect_semi()?;
 643                     }
 644                     LocalKind::Decl => return Err(e),
 645                 }
 646                 eat_semi = false;
 647             }
 648             StmtKind::Empty | StmtKind::Item(_) | StmtKind::Local(_) | StmtKind::Semi(_) => eat_semi = false,
 649         }
 650
 651         if eat_semi && self.eat(&token::Semi) {
 652             stmt = stmt.add_trailing_semicolon();
 653         }
 654         stmt.span = stmt.span.to(self.prev_token.span);
 655         Ok(Some(stmt))
 656     }
 657
 658     pub(super) fn mk_block(&self, stmts: Vec<Stmt>, rules: BlockCheckMode, span: Span) -> P<Block> {
 659         P(Block {
 660             stmts,
 661             id: DUMMY_NODE_ID,
 662             rules,
 663             span,
 664             tokens: None,
 665             could_be_bare_literal: false,
 666         })
 667     }
 668
 669     pub(super) fn mk_stmt(&self, span: Span, kind: StmtKind) -> Stmt {
 670         Stmt { id: DUMMY_NODE_ID, kind, span }
 671     }
 672
 673     pub(super) fn mk_stmt_err(&self, span: Span) -> Stmt {
 674         self.mk_stmt(span, StmtKind::Expr(self.mk_expr_err(span)))
 675     }
 676
 677     pub(super) fn mk_block_err(&self, span: Span) -> P<Block> {
 678         self.mk_block(vec![self.mk_stmt_err(span)], BlockCheckMode::Default, span)
 679     }
 680 }