1 pub mod attr;
2 mod attr_wrapper;
3 mod diagnostics;
4 mod expr;
5 mod generics;
6 mod item;
7 mod nonterminal;
8 mod pat;
9 mod path;
10 mod stmt;
11 mod ty;
12
13 use crate::lexer::UnmatchedBrace;
14 pub use attr_wrapper::AttrWrapper;
15 pub use diagnostics::AttemptLocalParseRecovery;
16 use diagnostics::Error;
17 pub use pat::{RecoverColon, RecoverComma};
18 pub use path::PathStyle;
19
20 use rustc_ast::ptr::P;
21 use rustc_ast::token::{self, DelimToken, Token, TokenKind};
22 use rustc_ast::tokenstream::AttributesData;
23 use rustc_ast::tokenstream::{self, DelimSpan, Spacing};
24 use rustc_ast::tokenstream::{TokenStream, TokenTree};
25 use rustc_ast::AttrId;
26 use rustc_ast::DUMMY_NODE_ID;
27 use rustc_ast::{self as ast, AnonConst, AstLike, AttrStyle, AttrVec, Const, CrateSugar, Extern};
28 use rustc_ast::{Async, Expr, ExprKind, MacArgs, MacDelimiter, Mutability, StrLit, Unsafe};
29 use rustc_ast::{Visibility, VisibilityKind};
30 use rustc_ast_pretty::pprust;
31 use rustc_data_structures::fx::FxHashMap;
32 use rustc_data_structures::sync::Lrc;
33 use rustc_errors::PResult;
34 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, FatalError};
35 use rustc_session::parse::ParseSess;
36 use rustc_span::source_map::{MultiSpan, Span, DUMMY_SP};
37 use rustc_span::symbol::{kw, sym, Ident, Symbol};
38 use tracing::debug;
39
40 use std::ops::Range;
41 use std::{cmp, mem, slice};
42
43 bitflags::bitflags! {
44 struct Restrictions: u8 {
45 const STMT_EXPR = 1 << 0;
46 const NO_STRUCT_LITERAL = 1 << 1;
47 const CONST_EXPR = 1 << 2;
48 }
49 }
50
51 #[derive(Clone, Copy, PartialEq, Debug)]
52 enum SemiColonMode {
53 Break,
54 Ignore,
55 Comma,
56 }
57
58 #[derive(Clone, Copy, PartialEq, Debug)]
59 enum BlockMode {
60 Break,
61 Ignore,
62 }
63
64 /// Whether or not we should force collection of tokens for an AST node,
65 /// regardless of whether or not it has attributes
66 #[derive(Clone, Copy, PartialEq)]
67 pub enum ForceCollect {
68 Yes,
69 No,
70 }
71
72 #[derive(Debug, Eq, PartialEq)]
73 pub enum TrailingToken {
74 None,
75 Semi,
76 /// If the trailing token is a comma, then capture it
77 /// Otherwise, ignore the trailing token
78 MaybeComma,
79 }
80
81 /// Like `maybe_whole_expr`, but for things other than expressions.
82 #[macro_export]
83 macro_rules! maybe_whole {
84 ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
85 if let token::Interpolated(nt) = &$p.token.kind {
86 if let token::$constructor(x) = &**nt {
87 let $x = x.clone();
88 $p.bump();
89 return Ok($e);
90 }
91 }
92 };
93 }
94
95 /// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`.
96 #[macro_export]
97 macro_rules! maybe_recover_from_interpolated_ty_qpath {
98 ($self: expr, $allow_qpath_recovery: expr) => {
99 if $allow_qpath_recovery && $self.look_ahead(1, |t| t == &token::ModSep) {
100 if let token::Interpolated(nt) = &$self.token.kind {
101 if let token::NtTy(ty) = &**nt {
102 let ty = ty.clone();
103 $self.bump();
104 return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_token.span, ty);
105 }
106 }
107 }
108 };
109 }
110
111 #[derive(Clone)]
112 pub struct Parser<'a> {
113 pub sess: &'a ParseSess,
114 /// The current token.
115 pub token: Token,
116 /// The spacing for the current token
117 pub token_spacing: Spacing,
118 /// The previous token.
119 pub prev_token: Token,
120 pub capture_cfg: bool,
121 restrictions: Restrictions,
122 expected_tokens: Vec<TokenType>,
123 // Important: This must only be advanced from `next_tok`
124 // to ensure that `token_cursor.num_next_calls` is updated properly
125 token_cursor: TokenCursor,
126 desugar_doc_comments: bool,
127 /// This field is used to keep track of how many left angle brackets we have seen. This is
128 /// required in order to detect extra leading left angle brackets (`<` characters) and error
129 /// appropriately.
130 ///
131 /// See the comments in the `parse_path_segment` function for more details.
132 unmatched_angle_bracket_count: u32,
133 max_angle_bracket_count: u32,
134 /// A list of all unclosed delimiters found by the lexer. If an entry is used for error recovery
135 /// it gets removed from here. Every entry left at the end gets emitted as an independent
136 /// error.
137 pub(super) unclosed_delims: Vec<UnmatchedBrace>,
138 last_unexpected_token_span: Option<Span>,
139 /// Span pointing at the `:` for the last type ascription the parser has seen, and whether it
140 /// looked like it could have been a mistyped path or literal `Option:Some(42)`).
141 pub last_type_ascription: Option<(Span, bool /* likely path typo */)>,
142 /// If present, this `Parser` is not parsing Rust code but rather a macro call.
143 subparser_name: Option<&'static str>,
144 capture_state: CaptureState,
145 /// This allows us to recover when the user forget to add braces around
146 /// multiple statements in the closure body.
147 pub current_closure: Option<ClosureSpans>,
148 }
149
150 /// Stores span informations about a closure.
151 #[derive(Clone)]
152 pub struct ClosureSpans {
153 pub whole_closure: Span,
154 pub closing_pipe: Span,
155 pub body: Span,
156 }
157
158 /// Indicates a range of tokens that should be replaced by
159 /// the tokens in the provided vector. This is used in two
160 /// places during token collection:
161 ///
162 /// 1. During the parsing of an AST node that may have a `#[derive]`
163 /// attribute, we parse a nested AST node that has `#[cfg]` or `#[cfg_attr]`
164 /// In this case, we use a `ReplaceRange` to replace the entire inner AST node
165 /// with `FlatToken::AttrTarget`, allowing us to perform eager cfg-expansion
166 /// on an `AttrAnnotatedTokenStream`
167 ///
168 /// 2. When we parse an inner attribute while collecting tokens. We
169 /// remove inner attributes from the token stream entirely, and
170 /// instead track them through the `attrs` field on the AST node.
171 /// This allows us to easily manipulate them (for example, removing
172 /// the first macro inner attribute to invoke a proc-macro).
173 /// When create a `TokenStream`, the inner attributes get inserted
174 /// into the proper place in the token stream.
175 pub type ReplaceRange = (Range<u32>, Vec<(FlatToken, Spacing)>);
176
177 /// Controls how we capture tokens. Capturing can be expensive,
178 /// so we try to avoid performing capturing in cases where
179 /// we will never need an `AttrAnnotatedTokenStream`
180 #[derive(Copy, Clone)]
181 pub enum Capturing {
182 /// We aren't performing any capturing - this is the default mode.
183 No,
184 /// We are capturing tokens
185 Yes,
186 }
187
188 #[derive(Clone)]
189 struct CaptureState {
190 capturing: Capturing,
191 replace_ranges: Vec<ReplaceRange>,
192 inner_attr_ranges: FxHashMap<AttrId, ReplaceRange>,
193 }
194
195 impl<'a> Drop for Parser<'a> {
drop(&mut self)196 fn drop(&mut self) {
197 emit_unclosed_delims(&mut self.unclosed_delims, &self.sess);
198 }
199 }
200
201 #[derive(Clone)]
202 struct TokenCursor {
203 frame: TokenCursorFrame,
204 stack: Vec<TokenCursorFrame>,
205 desugar_doc_comments: bool,
206 // Counts the number of calls to `next` or `next_desugared`,
207 // depending on whether `desugar_doc_comments` is set.
208 num_next_calls: usize,
209 // During parsing, we may sometimes need to 'unglue' a
210 // glued token into two component tokens
211 // (e.g. '>>' into '>' and '>), so that the parser
212 // can consume them one at a time. This process
213 // bypasses the normal capturing mechanism
214 // (e.g. `num_next_calls` will not be incremented),
215 // since the 'unglued' tokens due not exist in
216 // the original `TokenStream`.
217 //
218 // If we end up consuming both unglued tokens,
219 // then this is not an issue - we'll end up
220 // capturing the single 'glued' token.
221 //
222 // However, in certain circumstances, we may
223 // want to capture just the first 'unglued' token.
224 // For example, capturing the `Vec<u8>`
225 // in `Option<Vec<u8>>` requires us to unglue
226 // the trailing `>>` token. The `break_last_token`
227 // field is used to track this token - it gets
228 // appended to the captured stream when
229 // we evaluate a `LazyTokenStream`
230 break_last_token: bool,
231 }
232
233 #[derive(Clone)]
234 struct TokenCursorFrame {
235 delim: token::DelimToken,
236 span: DelimSpan,
237 open_delim: bool,
238 tree_cursor: tokenstream::Cursor,
239 close_delim: bool,
240 }
241
242 impl TokenCursorFrame {
new(span: DelimSpan, delim: DelimToken, tts: TokenStream) -> Self243 fn new(span: DelimSpan, delim: DelimToken, tts: TokenStream) -> Self {
244 TokenCursorFrame {
245 delim,
246 span,
247 open_delim: false,
248 tree_cursor: tts.into_trees(),
249 close_delim: false,
250 }
251 }
252 }
253
254 impl TokenCursor {
next(&mut self) -> (Token, Spacing)255 fn next(&mut self) -> (Token, Spacing) {
256 loop {
257 let (tree, spacing) = if !self.frame.open_delim {
258 self.frame.open_delim = true;
259 TokenTree::open_tt(self.frame.span, self.frame.delim).into()
260 } else if let Some(tree) = self.frame.tree_cursor.next_with_spacing() {
261 tree
262 } else if !self.frame.close_delim {
263 self.frame.close_delim = true;
264 TokenTree::close_tt(self.frame.span, self.frame.delim).into()
265 } else if let Some(frame) = self.stack.pop() {
266 self.frame = frame;
267 continue;
268 } else {
269 (TokenTree::Token(Token::new(token::Eof, DUMMY_SP)), Spacing::Alone)
270 };
271
272 match tree {
273 TokenTree::Token(token) => {
274 return (token, spacing);
275 }
276 TokenTree::Delimited(sp, delim, tts) => {
277 let frame = TokenCursorFrame::new(sp, delim, tts);
278 self.stack.push(mem::replace(&mut self.frame, frame));
279 }
280 }
281 }
282 }
283
next_desugared(&mut self) -> (Token, Spacing)284 fn next_desugared(&mut self) -> (Token, Spacing) {
285 let (data, attr_style, sp) = match self.next() {
286 (Token { kind: token::DocComment(_, attr_style, data), span }, _) => {
287 (data, attr_style, span)
288 }
289 tok => return tok,
290 };
291
292 // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
293 // required to wrap the text.
294 let mut num_of_hashes = 0;
295 let mut count = 0;
296 for ch in data.as_str().chars() {
297 count = match ch {
298 '"' => 1,
299 '#' if count > 0 => count + 1,
300 _ => 0,
301 };
302 num_of_hashes = cmp::max(num_of_hashes, count);
303 }
304
305 let delim_span = DelimSpan::from_single(sp);
306 let body = TokenTree::Delimited(
307 delim_span,
308 token::Bracket,
309 [
310 TokenTree::token(token::Ident(sym::doc, false), sp),
311 TokenTree::token(token::Eq, sp),
312 TokenTree::token(TokenKind::lit(token::StrRaw(num_of_hashes), data, None), sp),
313 ]
314 .iter()
315 .cloned()
316 .collect::<TokenStream>(),
317 );
318
319 self.stack.push(mem::replace(
320 &mut self.frame,
321 TokenCursorFrame::new(
322 delim_span,
323 token::NoDelim,
324 if attr_style == AttrStyle::Inner {
325 [TokenTree::token(token::Pound, sp), TokenTree::token(token::Not, sp), body]
326 .iter()
327 .cloned()
328 .collect::<TokenStream>()
329 } else {
330 [TokenTree::token(token::Pound, sp), body]
331 .iter()
332 .cloned()
333 .collect::<TokenStream>()
334 },
335 ),
336 ));
337
338 self.next()
339 }
340 }
341
342 #[derive(Debug, Clone, PartialEq)]
343 enum TokenType {
344 Token(TokenKind),
345 Keyword(Symbol),
346 Operator,
347 Lifetime,
348 Ident,
349 Path,
350 Type,
351 Const,
352 }
353
354 impl TokenType {
to_string(&self) -> String355 fn to_string(&self) -> String {
356 match *self {
357 TokenType::Token(ref t) => format!("`{}`", pprust::token_kind_to_string(t)),
358 TokenType::Keyword(kw) => format!("`{}`", kw),
359 TokenType::Operator => "an operator".to_string(),
360 TokenType::Lifetime => "lifetime".to_string(),
361 TokenType::Ident => "identifier".to_string(),
362 TokenType::Path => "path".to_string(),
363 TokenType::Type => "type".to_string(),
364 TokenType::Const => "a const expression".to_string(),
365 }
366 }
367 }
368
369 #[derive(Copy, Clone, Debug)]
370 enum TokenExpectType {
371 Expect,
372 NoExpect,
373 }
374
375 /// A sequence separator.
376 struct SeqSep {
377 /// The separator token.
378 sep: Option<TokenKind>,
379 /// `true` if a trailing separator is allowed.
380 trailing_sep_allowed: bool,
381 }
382
383 impl SeqSep {
trailing_allowed(t: TokenKind) -> SeqSep384 fn trailing_allowed(t: TokenKind) -> SeqSep {
385 SeqSep { sep: Some(t), trailing_sep_allowed: true }
386 }
387
none() -> SeqSep388 fn none() -> SeqSep {
389 SeqSep { sep: None, trailing_sep_allowed: false }
390 }
391 }
392
393 pub enum FollowedByType {
394 Yes,
395 No,
396 }
397
token_descr_opt(token: &Token) -> Option<&'static str>398 fn token_descr_opt(token: &Token) -> Option<&'static str> {
399 Some(match token.kind {
400 _ if token.is_special_ident() => "reserved identifier",
401 _ if token.is_used_keyword() => "keyword",
402 _ if token.is_unused_keyword() => "reserved keyword",
403 token::DocComment(..) => "doc comment",
404 _ => return None,
405 })
406 }
407
token_descr(token: &Token) -> String408 pub(super) fn token_descr(token: &Token) -> String {
409 let token_str = pprust::token_to_string(token);
410 match token_descr_opt(token) {
411 Some(prefix) => format!("{} `{}`", prefix, token_str),
412 _ => format!("`{}`", token_str),
413 }
414 }
415
416 impl<'a> Parser<'a> {
new( sess: &'a ParseSess, tokens: TokenStream, desugar_doc_comments: bool, subparser_name: Option<&'static str>, ) -> Self417 pub fn new(
418 sess: &'a ParseSess,
419 tokens: TokenStream,
420 desugar_doc_comments: bool,
421 subparser_name: Option<&'static str>,
422 ) -> Self {
423 let mut start_frame = TokenCursorFrame::new(DelimSpan::dummy(), token::NoDelim, tokens);
424 start_frame.open_delim = true;
425 start_frame.close_delim = true;
426
427 let mut parser = Parser {
428 sess,
429 token: Token::dummy(),
430 token_spacing: Spacing::Alone,
431 prev_token: Token::dummy(),
432 capture_cfg: false,
433 restrictions: Restrictions::empty(),
434 expected_tokens: Vec::new(),
435 token_cursor: TokenCursor {
436 frame: start_frame,
437 stack: Vec::new(),
438 num_next_calls: 0,
439 desugar_doc_comments,
440 break_last_token: false,
441 },
442 desugar_doc_comments,
443 unmatched_angle_bracket_count: 0,
444 max_angle_bracket_count: 0,
445 unclosed_delims: Vec::new(),
446 last_unexpected_token_span: None,
447 last_type_ascription: None,
448 subparser_name,
449 capture_state: CaptureState {
450 capturing: Capturing::No,
451 replace_ranges: Vec::new(),
452 inner_attr_ranges: Default::default(),
453 },
454 current_closure: None,
455 };
456
457 // Make parser point to the first token.
458 parser.bump();
459
460 parser
461 }
462
next_tok(&mut self, fallback_span: Span) -> (Token, Spacing)463 fn next_tok(&mut self, fallback_span: Span) -> (Token, Spacing) {
464 loop {
465 let (mut next, spacing) = if self.desugar_doc_comments {
466 self.token_cursor.next_desugared()
467 } else {
468 self.token_cursor.next()
469 };
470 self.token_cursor.num_next_calls += 1;
471 // We've retrieved an token from the underlying
472 // cursor, so we no longer need to worry about
473 // an unglued token. See `break_and_eat` for more details
474 self.token_cursor.break_last_token = false;
475 if next.span.is_dummy() {
476 // Tweak the location for better diagnostics, but keep syntactic context intact.
477 next.span = fallback_span.with_ctxt(next.span.ctxt());
478 }
479 if matches!(
480 next.kind,
481 token::OpenDelim(token::NoDelim) | token::CloseDelim(token::NoDelim)
482 ) {
483 continue;
484 }
485 return (next, spacing);
486 }
487 }
488
unexpected<T>(&mut self) -> PResult<'a, T>489 pub fn unexpected<T>(&mut self) -> PResult<'a, T> {
490 match self.expect_one_of(&[], &[]) {
491 Err(e) => Err(e),
492 // We can get `Ok(true)` from `recover_closing_delimiter`
493 // which is called in `expected_one_of_not_found`.
494 Ok(_) => FatalError.raise(),
495 }
496 }
497
498 /// Expects and consumes the token `t`. Signals an error if the next token is not `t`.
expect(&mut self, t: &TokenKind) -> PResult<'a, bool >499 pub fn expect(&mut self, t: &TokenKind) -> PResult<'a, bool /* recovered */> {
500 if self.expected_tokens.is_empty() {
501 if self.token == *t {
502 self.bump();
503 Ok(false)
504 } else {
505 self.unexpected_try_recover(t)
506 }
507 } else {
508 self.expect_one_of(slice::from_ref(t), &[])
509 }
510 }
511
512 /// Expect next token to be edible or inedible token. If edible,
513 /// then consume it; if inedible, then return without consuming
514 /// anything. Signal a fatal error if next token is unexpected.
expect_one_of( &mut self, edible: &[TokenKind], inedible: &[TokenKind], ) -> PResult<'a, bool >515 pub fn expect_one_of(
516 &mut self,
517 edible: &[TokenKind],
518 inedible: &[TokenKind],
519 ) -> PResult<'a, bool /* recovered */> {
520 if edible.contains(&self.token.kind) {
521 self.bump();
522 Ok(false)
523 } else if inedible.contains(&self.token.kind) {
524 // leave it in the input
525 Ok(false)
526 } else if self.last_unexpected_token_span == Some(self.token.span) {
527 FatalError.raise();
528 } else {
529 self.expected_one_of_not_found(edible, inedible)
530 }
531 }
532
533 // Public for rustfmt usage.
parse_ident(&mut self) -> PResult<'a, Ident>534 pub fn parse_ident(&mut self) -> PResult<'a, Ident> {
535 self.parse_ident_common(true)
536 }
537
ident_or_err(&mut self) -> PResult<'a, (Ident, bool)>538 fn ident_or_err(&mut self) -> PResult<'a, (Ident, /* is_raw */ bool)> {
539 self.token.ident().ok_or_else(|| match self.prev_token.kind {
540 TokenKind::DocComment(..) => {
541 self.span_err(self.prev_token.span, Error::UselessDocComment)
542 }
543 _ => self.expected_ident_found(),
544 })
545 }
546
parse_ident_common(&mut self, recover: bool) -> PResult<'a, Ident>547 fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, Ident> {
548 let (ident, is_raw) = self.ident_or_err()?;
549 if !is_raw && ident.is_reserved() {
550 let mut err = self.expected_ident_found();
551 if recover {
552 err.emit();
553 } else {
554 return Err(err);
555 }
556 }
557 self.bump();
558 Ok(ident)
559 }
560
561 /// Checks if the next token is `tok`, and returns `true` if so.
562 ///
563 /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
564 /// encountered.
check(&mut self, tok: &TokenKind) -> bool565 fn check(&mut self, tok: &TokenKind) -> bool {
566 let is_present = self.token == *tok;
567 if !is_present {
568 self.expected_tokens.push(TokenType::Token(tok.clone()));
569 }
570 is_present
571 }
572
573 /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
eat(&mut self, tok: &TokenKind) -> bool574 pub fn eat(&mut self, tok: &TokenKind) -> bool {
575 let is_present = self.check(tok);
576 if is_present {
577 self.bump()
578 }
579 is_present
580 }
581
582 /// If the next token is the given keyword, returns `true` without eating it.
583 /// An expectation is also added for diagnostics purposes.
check_keyword(&mut self, kw: Symbol) -> bool584 fn check_keyword(&mut self, kw: Symbol) -> bool {
585 self.expected_tokens.push(TokenType::Keyword(kw));
586 self.token.is_keyword(kw)
587 }
588
589 /// If the next token is the given keyword, eats it and returns `true`.
590 /// Otherwise, returns `false`. An expectation is also added for diagnostics purposes.
591 // Public for rustfmt usage.
eat_keyword(&mut self, kw: Symbol) -> bool592 pub fn eat_keyword(&mut self, kw: Symbol) -> bool {
593 if self.check_keyword(kw) {
594 self.bump();
595 true
596 } else {
597 false
598 }
599 }
600
eat_keyword_noexpect(&mut self, kw: Symbol) -> bool601 fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
602 if self.token.is_keyword(kw) {
603 self.bump();
604 true
605 } else {
606 false
607 }
608 }
609
610 /// If the given word is not a keyword, signals an error.
611 /// If the next token is not the given word, signals an error.
612 /// Otherwise, eats it.
expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()>613 fn expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()> {
614 if !self.eat_keyword(kw) { self.unexpected() } else { Ok(()) }
615 }
616
617 /// Is the given keyword `kw` followed by a non-reserved identifier?
is_kw_followed_by_ident(&self, kw: Symbol) -> bool618 fn is_kw_followed_by_ident(&self, kw: Symbol) -> bool {
619 self.token.is_keyword(kw) && self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
620 }
621
check_or_expected(&mut self, ok: bool, typ: TokenType) -> bool622 fn check_or_expected(&mut self, ok: bool, typ: TokenType) -> bool {
623 if ok {
624 true
625 } else {
626 self.expected_tokens.push(typ);
627 false
628 }
629 }
630
check_ident(&mut self) -> bool631 fn check_ident(&mut self) -> bool {
632 self.check_or_expected(self.token.is_ident(), TokenType::Ident)
633 }
634
check_path(&mut self) -> bool635 fn check_path(&mut self) -> bool {
636 self.check_or_expected(self.token.is_path_start(), TokenType::Path)
637 }
638
check_type(&mut self) -> bool639 fn check_type(&mut self) -> bool {
640 self.check_or_expected(self.token.can_begin_type(), TokenType::Type)
641 }
642
check_const_arg(&mut self) -> bool643 fn check_const_arg(&mut self) -> bool {
644 self.check_or_expected(self.token.can_begin_const_arg(), TokenType::Const)
645 }
646
check_inline_const(&self, dist: usize) -> bool647 fn check_inline_const(&self, dist: usize) -> bool {
648 self.is_keyword_ahead(dist, &[kw::Const])
649 && self.look_ahead(dist + 1, |t| match t.kind {
650 token::Interpolated(ref nt) => matches!(**nt, token::NtBlock(..)),
651 token::OpenDelim(DelimToken::Brace) => true,
652 _ => false,
653 })
654 }
655
656 /// Checks to see if the next token is either `+` or `+=`.
657 /// Otherwise returns `false`.
check_plus(&mut self) -> bool658 fn check_plus(&mut self) -> bool {
659 self.check_or_expected(
660 self.token.is_like_plus(),
661 TokenType::Token(token::BinOp(token::Plus)),
662 )
663 }
664
665 /// Eats the expected token if it's present possibly breaking
666 /// compound tokens like multi-character operators in process.
667 /// Returns `true` if the token was eaten.
break_and_eat(&mut self, expected: TokenKind) -> bool668 fn break_and_eat(&mut self, expected: TokenKind) -> bool {
669 if self.token.kind == expected {
670 self.bump();
671 return true;
672 }
673 match self.token.kind.break_two_token_op() {
674 Some((first, second)) if first == expected => {
675 let first_span = self.sess.source_map().start_point(self.token.span);
676 let second_span = self.token.span.with_lo(first_span.hi());
677 self.token = Token::new(first, first_span);
678 // Keep track of this token - if we end token capturing now,
679 // we'll want to append this token to the captured stream.
680 //
681 // If we consume any additional tokens, then this token
682 // is not needed (we'll capture the entire 'glued' token),
683 // and `next_tok` will set this field to `None`
684 self.token_cursor.break_last_token = true;
685 // Use the spacing of the glued token as the spacing
686 // of the unglued second token.
687 self.bump_with((Token::new(second, second_span), self.token_spacing));
688 true
689 }
690 _ => {
691 self.expected_tokens.push(TokenType::Token(expected));
692 false
693 }
694 }
695 }
696
697 /// Eats `+` possibly breaking tokens like `+=` in process.
eat_plus(&mut self) -> bool698 fn eat_plus(&mut self) -> bool {
699 self.break_and_eat(token::BinOp(token::Plus))
700 }
701
702 /// Eats `&` possibly breaking tokens like `&&` in process.
703 /// Signals an error if `&` is not eaten.
expect_and(&mut self) -> PResult<'a, ()>704 fn expect_and(&mut self) -> PResult<'a, ()> {
705 if self.break_and_eat(token::BinOp(token::And)) { Ok(()) } else { self.unexpected() }
706 }
707
708 /// Eats `|` possibly breaking tokens like `||` in process.
709 /// Signals an error if `|` was not eaten.
expect_or(&mut self) -> PResult<'a, ()>710 fn expect_or(&mut self) -> PResult<'a, ()> {
711 if self.break_and_eat(token::BinOp(token::Or)) { Ok(()) } else { self.unexpected() }
712 }
713
714 /// Eats `<` possibly breaking tokens like `<<` in process.
eat_lt(&mut self) -> bool715 fn eat_lt(&mut self) -> bool {
716 let ate = self.break_and_eat(token::Lt);
717 if ate {
718 // See doc comment for `unmatched_angle_bracket_count`.
719 self.unmatched_angle_bracket_count += 1;
720 self.max_angle_bracket_count += 1;
721 debug!("eat_lt: (increment) count={:?}", self.unmatched_angle_bracket_count);
722 }
723 ate
724 }
725
726 /// Eats `<` possibly breaking tokens like `<<` in process.
727 /// Signals an error if `<` was not eaten.
expect_lt(&mut self) -> PResult<'a, ()>728 fn expect_lt(&mut self) -> PResult<'a, ()> {
729 if self.eat_lt() { Ok(()) } else { self.unexpected() }
730 }
731
732 /// Eats `>` possibly breaking tokens like `>>` in process.
733 /// Signals an error if `>` was not eaten.
expect_gt(&mut self) -> PResult<'a, ()>734 fn expect_gt(&mut self) -> PResult<'a, ()> {
735 if self.break_and_eat(token::Gt) {
736 // See doc comment for `unmatched_angle_bracket_count`.
737 if self.unmatched_angle_bracket_count > 0 {
738 self.unmatched_angle_bracket_count -= 1;
739 debug!("expect_gt: (decrement) count={:?}", self.unmatched_angle_bracket_count);
740 }
741 Ok(())
742 } else {
743 self.unexpected()
744 }
745 }
746
expect_any_with_type(&mut self, kets: &[&TokenKind], expect: TokenExpectType) -> bool747 fn expect_any_with_type(&mut self, kets: &[&TokenKind], expect: TokenExpectType) -> bool {
748 kets.iter().any(|k| match expect {
749 TokenExpectType::Expect => self.check(k),
750 TokenExpectType::NoExpect => self.token == **k,
751 })
752 }
753
parse_seq_to_before_tokens<T>( &mut self, kets: &[&TokenKind], sep: SeqSep, expect: TokenExpectType, mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, ) -> PResult<'a, (Vec<T>, bool , bool )>754 fn parse_seq_to_before_tokens<T>(
755 &mut self,
756 kets: &[&TokenKind],
757 sep: SeqSep,
758 expect: TokenExpectType,
759 mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
760 ) -> PResult<'a, (Vec<T>, bool /* trailing */, bool /* recovered */)> {
761 let mut first = true;
762 let mut recovered = false;
763 let mut trailing = false;
764 let mut v = vec![];
765 let unclosed_delims = !self.unclosed_delims.is_empty();
766
767 while !self.expect_any_with_type(kets, expect) {
768 if let token::CloseDelim(..) | token::Eof = self.token.kind {
769 break;
770 }
771 if let Some(ref t) = sep.sep {
772 if first {
773 first = false;
774 } else {
775 match self.expect(t) {
776 Ok(false) => {
777 self.current_closure.take();
778 }
779 Ok(true) => {
780 self.current_closure.take();
781 recovered = true;
782 break;
783 }
784 Err(mut expect_err) => {
785 let sp = self.prev_token.span.shrink_to_hi();
786 let token_str = pprust::token_kind_to_string(t);
787
788 match self.current_closure.take() {
789 Some(closure_spans) if self.token.kind == TokenKind::Semi => {
790 // Finding a semicolon instead of a comma
791 // after a closure body indicates that the
792 // closure body may be a block but the user
793 // forgot to put braces around its
794 // statements.
795
796 self.recover_missing_braces_around_closure_body(
797 closure_spans,
798 expect_err,
799 )?;
800
801 continue;
802 }
803
804 _ => {
805 // Attempt to keep parsing if it was a similar separator.
806 if let Some(ref tokens) = t.similar_tokens() {
807 if tokens.contains(&self.token.kind) && !unclosed_delims {
808 self.bump();
809 }
810 }
811 }
812 }
813
814 // If this was a missing `@` in a binding pattern
815 // bail with a suggestion
816 // https://github.com/rust-lang/rust/issues/72373
817 if self.prev_token.is_ident() && self.token.kind == token::DotDot {
818 let msg = format!(
819 "if you meant to bind the contents of \
820 the rest of the array pattern into `{}`, use `@`",
821 pprust::token_to_string(&self.prev_token)
822 );
823 expect_err
824 .span_suggestion_verbose(
825 self.prev_token.span.shrink_to_hi().until(self.token.span),
826 &msg,
827 " @ ".to_string(),
828 Applicability::MaybeIncorrect,
829 )
830 .emit();
831 break;
832 }
833
834 // Attempt to keep parsing if it was an omitted separator.
835 match f(self) {
836 Ok(t) => {
837 // Parsed successfully, therefore most probably the code only
838 // misses a separator.
839 expect_err
840 .span_suggestion_short(
841 sp,
842 &format!("missing `{}`", token_str),
843 token_str.into(),
844 Applicability::MaybeIncorrect,
845 )
846 .emit();
847
848 v.push(t);
849 continue;
850 }
851 Err(mut e) => {
852 // Parsing failed, therefore it must be something more serious
853 // than just a missing separator.
854 expect_err.emit();
855
856 e.cancel();
857 break;
858 }
859 }
860 }
861 }
862 }
863 }
864 if sep.trailing_sep_allowed && self.expect_any_with_type(kets, expect) {
865 trailing = true;
866 break;
867 }
868
869 let t = f(self)?;
870 v.push(t);
871 }
872
873 Ok((v, trailing, recovered))
874 }
875
recover_missing_braces_around_closure_body( &mut self, closure_spans: ClosureSpans, mut expect_err: DiagnosticBuilder<'_>, ) -> PResult<'a, ()>876 fn recover_missing_braces_around_closure_body(
877 &mut self,
878 closure_spans: ClosureSpans,
879 mut expect_err: DiagnosticBuilder<'_>,
880 ) -> PResult<'a, ()> {
881 let initial_semicolon = self.token.span;
882
883 while self.eat(&TokenKind::Semi) {
884 let _ = self.parse_stmt(ForceCollect::Yes)?;
885 }
886
887 expect_err.set_primary_message(
888 "closure bodies that contain statements must be surrounded by braces",
889 );
890
891 let preceding_pipe_span = closure_spans.closing_pipe;
892 let following_token_span = self.token.span;
893
894 let mut first_note = MultiSpan::from(vec![initial_semicolon]);
895 first_note.push_span_label(
896 initial_semicolon,
897 "this `;` turns the preceding closure into a statement".to_string(),
898 );
899 first_note.push_span_label(
900 closure_spans.body,
901 "this expression is a statement because of the trailing semicolon".to_string(),
902 );
903 expect_err.span_note(first_note, "statement found outside of a block");
904
905 let mut second_note = MultiSpan::from(vec![closure_spans.whole_closure]);
906 second_note.push_span_label(
907 closure_spans.whole_closure,
908 "this is the parsed closure...".to_string(),
909 );
910 second_note.push_span_label(
911 following_token_span,
912 "...but likely you meant the closure to end here".to_string(),
913 );
914 expect_err.span_note(second_note, "the closure body may be incorrectly delimited");
915
916 expect_err.set_span(vec![preceding_pipe_span, following_token_span]);
917
918 let opening_suggestion_str = " {".to_string();
919 let closing_suggestion_str = "}".to_string();
920
921 expect_err.multipart_suggestion(
922 "try adding braces",
923 vec![
924 (preceding_pipe_span.shrink_to_hi(), opening_suggestion_str),
925 (following_token_span.shrink_to_lo(), closing_suggestion_str),
926 ],
927 Applicability::MaybeIncorrect,
928 );
929
930 expect_err.emit();
931
932 Ok(())
933 }
934
935 /// Parses a sequence, not including the closing delimiter. The function
936 /// `f` must consume tokens until reaching the next separator or
937 /// closing bracket.
parse_seq_to_before_end<T>( &mut self, ket: &TokenKind, sep: SeqSep, f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, ) -> PResult<'a, (Vec<T>, bool, bool)>938 fn parse_seq_to_before_end<T>(
939 &mut self,
940 ket: &TokenKind,
941 sep: SeqSep,
942 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
943 ) -> PResult<'a, (Vec<T>, bool, bool)> {
944 self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
945 }
946
947 /// Parses a sequence, including the closing delimiter. The function
948 /// `f` must consume tokens until reaching the next separator or
949 /// closing bracket.
parse_seq_to_end<T>( &mut self, ket: &TokenKind, sep: SeqSep, f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, ) -> PResult<'a, (Vec<T>, bool )>950 fn parse_seq_to_end<T>(
951 &mut self,
952 ket: &TokenKind,
953 sep: SeqSep,
954 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
955 ) -> PResult<'a, (Vec<T>, bool /* trailing */)> {
956 let (val, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
957 if !recovered {
958 self.eat(ket);
959 }
960 Ok((val, trailing))
961 }
962
963 /// Parses a sequence, including the closing delimiter. The function
964 /// `f` must consume tokens until reaching the next separator or
965 /// closing bracket.
parse_unspanned_seq<T>( &mut self, bra: &TokenKind, ket: &TokenKind, sep: SeqSep, f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, ) -> PResult<'a, (Vec<T>, bool)>966 fn parse_unspanned_seq<T>(
967 &mut self,
968 bra: &TokenKind,
969 ket: &TokenKind,
970 sep: SeqSep,
971 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
972 ) -> PResult<'a, (Vec<T>, bool)> {
973 self.expect(bra)?;
974 self.parse_seq_to_end(ket, sep, f)
975 }
976
parse_delim_comma_seq<T>( &mut self, delim: DelimToken, f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, ) -> PResult<'a, (Vec<T>, bool)>977 fn parse_delim_comma_seq<T>(
978 &mut self,
979 delim: DelimToken,
980 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
981 ) -> PResult<'a, (Vec<T>, bool)> {
982 self.parse_unspanned_seq(
983 &token::OpenDelim(delim),
984 &token::CloseDelim(delim),
985 SeqSep::trailing_allowed(token::Comma),
986 f,
987 )
988 }
989
parse_paren_comma_seq<T>( &mut self, f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, ) -> PResult<'a, (Vec<T>, bool)>990 fn parse_paren_comma_seq<T>(
991 &mut self,
992 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
993 ) -> PResult<'a, (Vec<T>, bool)> {
994 self.parse_delim_comma_seq(token::Paren, f)
995 }
996
997 /// Advance the parser by one token using provided token as the next one.
bump_with(&mut self, (next_token, next_spacing): (Token, Spacing))998 fn bump_with(&mut self, (next_token, next_spacing): (Token, Spacing)) {
999 // Bumping after EOF is a bad sign, usually an infinite loop.
1000 if self.prev_token.kind == TokenKind::Eof {
1001 let msg = "attempted to bump the parser past EOF (may be stuck in a loop)";
1002 self.span_bug(self.token.span, msg);
1003 }
1004
1005 // Update the current and previous tokens.
1006 self.prev_token = mem::replace(&mut self.token, next_token);
1007 self.token_spacing = next_spacing;
1008
1009 // Diagnostics.
1010 self.expected_tokens.clear();
1011 }
1012
1013 /// Advance the parser by one token.
bump(&mut self)1014 pub fn bump(&mut self) {
1015 let next_token = self.next_tok(self.token.span);
1016 self.bump_with(next_token);
1017 }
1018
1019 /// Look-ahead `dist` tokens of `self.token` and get access to that token there.
1020 /// When `dist == 0` then the current token is looked at.
look_ahead<R>(&self, dist: usize, looker: impl FnOnce(&Token) -> R) -> R1021 pub fn look_ahead<R>(&self, dist: usize, looker: impl FnOnce(&Token) -> R) -> R {
1022 if dist == 0 {
1023 return looker(&self.token);
1024 }
1025
1026 let frame = &self.token_cursor.frame;
1027 if frame.delim != DelimToken::NoDelim {
1028 let all_normal = (0..dist).all(|i| {
1029 let token = frame.tree_cursor.look_ahead(i);
1030 !matches!(token, Some(TokenTree::Delimited(_, DelimToken::NoDelim, _)))
1031 });
1032 if all_normal {
1033 return match frame.tree_cursor.look_ahead(dist - 1) {
1034 Some(tree) => match tree {
1035 TokenTree::Token(token) => looker(token),
1036 TokenTree::Delimited(dspan, delim, _) => {
1037 looker(&Token::new(token::OpenDelim(*delim), dspan.open))
1038 }
1039 },
1040 None => looker(&Token::new(token::CloseDelim(frame.delim), frame.span.close)),
1041 };
1042 }
1043 }
1044
1045 let mut cursor = self.token_cursor.clone();
1046 let mut i = 0;
1047 let mut token = Token::dummy();
1048 while i < dist {
1049 token = cursor.next().0;
1050 if matches!(
1051 token.kind,
1052 token::OpenDelim(token::NoDelim) | token::CloseDelim(token::NoDelim)
1053 ) {
1054 continue;
1055 }
1056 i += 1;
1057 }
1058 return looker(&token);
1059 }
1060
1061 /// Returns whether any of the given keywords are `dist` tokens ahead of the current one.
is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool1062 fn is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool {
1063 self.look_ahead(dist, |t| kws.iter().any(|&kw| t.is_keyword(kw)))
1064 }
1065
1066 /// Parses asyncness: `async` or nothing.
parse_asyncness(&mut self) -> Async1067 fn parse_asyncness(&mut self) -> Async {
1068 if self.eat_keyword(kw::Async) {
1069 let span = self.prev_token.uninterpolated_span();
1070 Async::Yes { span, closure_id: DUMMY_NODE_ID, return_impl_trait_id: DUMMY_NODE_ID }
1071 } else {
1072 Async::No
1073 }
1074 }
1075
1076 /// Parses unsafety: `unsafe` or nothing.
parse_unsafety(&mut self) -> Unsafe1077 fn parse_unsafety(&mut self) -> Unsafe {
1078 if self.eat_keyword(kw::Unsafe) {
1079 Unsafe::Yes(self.prev_token.uninterpolated_span())
1080 } else {
1081 Unsafe::No
1082 }
1083 }
1084
1085 /// Parses constness: `const` or nothing.
parse_constness(&mut self) -> Const1086 fn parse_constness(&mut self) -> Const {
1087 // Avoid const blocks to be parsed as const items
1088 if self.look_ahead(1, |t| t != &token::OpenDelim(DelimToken::Brace))
1089 && self.eat_keyword(kw::Const)
1090 {
1091 Const::Yes(self.prev_token.uninterpolated_span())
1092 } else {
1093 Const::No
1094 }
1095 }
1096
1097 /// Parses inline const expressions.
parse_const_block(&mut self, span: Span, pat: bool) -> PResult<'a, P<Expr>>1098 fn parse_const_block(&mut self, span: Span, pat: bool) -> PResult<'a, P<Expr>> {
1099 if pat {
1100 self.sess.gated_spans.gate(sym::inline_const_pat, span);
1101 } else {
1102 self.sess.gated_spans.gate(sym::inline_const, span);
1103 }
1104 self.eat_keyword(kw::Const);
1105 let blk = self.parse_block()?;
1106 let anon_const = AnonConst {
1107 id: DUMMY_NODE_ID,
1108 value: self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new()),
1109 };
1110 let blk_span = anon_const.value.span;
1111 Ok(self.mk_expr(span.to(blk_span), ExprKind::ConstBlock(anon_const), AttrVec::new()))
1112 }
1113
1114 /// Parses mutability (`mut` or nothing).
parse_mutability(&mut self) -> Mutability1115 fn parse_mutability(&mut self) -> Mutability {
1116 if self.eat_keyword(kw::Mut) { Mutability::Mut } else { Mutability::Not }
1117 }
1118
1119 /// Possibly parses mutability (`const` or `mut`).
parse_const_or_mut(&mut self) -> Option<Mutability>1120 fn parse_const_or_mut(&mut self) -> Option<Mutability> {
1121 if self.eat_keyword(kw::Mut) {
1122 Some(Mutability::Mut)
1123 } else if self.eat_keyword(kw::Const) {
1124 Some(Mutability::Not)
1125 } else {
1126 None
1127 }
1128 }
1129
parse_field_name(&mut self) -> PResult<'a, Ident>1130 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
1131 if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) = self.token.kind
1132 {
1133 self.expect_no_suffix(self.token.span, "a tuple index", suffix);
1134 self.bump();
1135 Ok(Ident::new(symbol, self.prev_token.span))
1136 } else {
1137 self.parse_ident_common(true)
1138 }
1139 }
1140
parse_mac_args(&mut self) -> PResult<'a, P<MacArgs>>1141 fn parse_mac_args(&mut self) -> PResult<'a, P<MacArgs>> {
1142 self.parse_mac_args_common(true).map(P)
1143 }
1144
parse_attr_args(&mut self) -> PResult<'a, MacArgs>1145 fn parse_attr_args(&mut self) -> PResult<'a, MacArgs> {
1146 self.parse_mac_args_common(false)
1147 }
1148
parse_mac_args_common(&mut self, delimited_only: bool) -> PResult<'a, MacArgs>1149 fn parse_mac_args_common(&mut self, delimited_only: bool) -> PResult<'a, MacArgs> {
1150 Ok(
1151 if self.check(&token::OpenDelim(DelimToken::Paren))
1152 || self.check(&token::OpenDelim(DelimToken::Bracket))
1153 || self.check(&token::OpenDelim(DelimToken::Brace))
1154 {
1155 match self.parse_token_tree() {
1156 TokenTree::Delimited(dspan, delim, tokens) =>
1157 // We've confirmed above that there is a delimiter so unwrapping is OK.
1158 {
1159 MacArgs::Delimited(dspan, MacDelimiter::from_token(delim).unwrap(), tokens)
1160 }
1161 _ => unreachable!(),
1162 }
1163 } else if !delimited_only {
1164 if self.eat(&token::Eq) {
1165 let eq_span = self.prev_token.span;
1166
1167 // Collect tokens because they are used during lowering to HIR.
1168 let expr = self.parse_expr_force_collect()?;
1169 let span = expr.span;
1170
1171 let token_kind = token::Interpolated(Lrc::new(token::NtExpr(expr)));
1172 MacArgs::Eq(eq_span, Token::new(token_kind, span))
1173 } else {
1174 MacArgs::Empty
1175 }
1176 } else {
1177 return self.unexpected();
1178 },
1179 )
1180 }
1181
parse_or_use_outer_attributes( &mut self, already_parsed_attrs: Option<AttrWrapper>, ) -> PResult<'a, AttrWrapper>1182 fn parse_or_use_outer_attributes(
1183 &mut self,
1184 already_parsed_attrs: Option<AttrWrapper>,
1185 ) -> PResult<'a, AttrWrapper> {
1186 if let Some(attrs) = already_parsed_attrs {
1187 Ok(attrs)
1188 } else {
1189 self.parse_outer_attributes()
1190 }
1191 }
1192
1193 /// Parses a single token tree from the input.
parse_token_tree(&mut self) -> TokenTree1194 pub(crate) fn parse_token_tree(&mut self) -> TokenTree {
1195 match self.token.kind {
1196 token::OpenDelim(..) => {
1197 let depth = self.token_cursor.stack.len();
1198
1199 // We keep advancing the token cursor until we hit
1200 // the matching `CloseDelim` token.
1201 while !(depth == self.token_cursor.stack.len()
1202 && matches!(self.token.kind, token::CloseDelim(_)))
1203 {
1204 // Advance one token at a time, so `TokenCursor::next()`
1205 // can capture these tokens if necessary.
1206 self.bump();
1207 }
1208 // We are still inside the frame corresponding
1209 // to the delimited stream we captured, so grab
1210 // the tokens from this frame.
1211 let frame = &self.token_cursor.frame;
1212 let stream = frame.tree_cursor.stream.clone();
1213 let span = frame.span;
1214 let delim = frame.delim;
1215 // Consume close delimiter
1216 self.bump();
1217 TokenTree::Delimited(span, delim, stream)
1218 }
1219 token::CloseDelim(_) | token::Eof => unreachable!(),
1220 _ => {
1221 self.bump();
1222 TokenTree::Token(self.prev_token.clone())
1223 }
1224 }
1225 }
1226
1227 /// Parses a stream of tokens into a list of `TokenTree`s, up to EOF.
parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>>1228 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
1229 let mut tts = Vec::new();
1230 while self.token != token::Eof {
1231 tts.push(self.parse_token_tree());
1232 }
1233 Ok(tts)
1234 }
1235
parse_tokens(&mut self) -> TokenStream1236 pub fn parse_tokens(&mut self) -> TokenStream {
1237 let mut result = Vec::new();
1238 loop {
1239 match self.token.kind {
1240 token::Eof | token::CloseDelim(..) => break,
1241 _ => result.push(self.parse_token_tree().into()),
1242 }
1243 }
1244 TokenStream::new(result)
1245 }
1246
1247 /// Evaluates the closure with restrictions in place.
1248 ///
1249 /// Afters the closure is evaluated, restrictions are reset.
with_res<T>(&mut self, res: Restrictions, f: impl FnOnce(&mut Self) -> T) -> T1250 fn with_res<T>(&mut self, res: Restrictions, f: impl FnOnce(&mut Self) -> T) -> T {
1251 let old = self.restrictions;
1252 self.restrictions = res;
1253 let res = f(self);
1254 self.restrictions = old;
1255 res
1256 }
1257
is_crate_vis(&self) -> bool1258 fn is_crate_vis(&self) -> bool {
1259 self.token.is_keyword(kw::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
1260 }
1261
1262 /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
1263 /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
1264 /// If the following element can't be a tuple (i.e., it's a function definition), then
1265 /// it's not a tuple struct field), and the contents within the parentheses aren't valid,
1266 /// so emit a proper diagnostic.
1267 // Public for rustfmt usage.
parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility>1268 pub fn parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility> {
1269 maybe_whole!(self, NtVis, |x| x);
1270
1271 self.expected_tokens.push(TokenType::Keyword(kw::Crate));
1272 if self.is_crate_vis() {
1273 self.bump(); // `crate`
1274 self.sess.gated_spans.gate(sym::crate_visibility_modifier, self.prev_token.span);
1275 return Ok(Visibility {
1276 span: self.prev_token.span,
1277 kind: VisibilityKind::Crate(CrateSugar::JustCrate),
1278 tokens: None,
1279 });
1280 }
1281
1282 if !self.eat_keyword(kw::Pub) {
1283 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
1284 // keyword to grab a span from for inherited visibility; an empty span at the
1285 // beginning of the current token would seem to be the "Schelling span".
1286 return Ok(Visibility {
1287 span: self.token.span.shrink_to_lo(),
1288 kind: VisibilityKind::Inherited,
1289 tokens: None,
1290 });
1291 }
1292 let lo = self.prev_token.span;
1293
1294 if self.check(&token::OpenDelim(token::Paren)) {
1295 // We don't `self.bump()` the `(` yet because this might be a struct definition where
1296 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
1297 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
1298 // by the following tokens.
1299 if self.is_keyword_ahead(1, &[kw::Crate]) && self.look_ahead(2, |t| t != &token::ModSep)
1300 // account for `pub(crate::foo)`
1301 {
1302 // Parse `pub(crate)`.
1303 self.bump(); // `(`
1304 self.bump(); // `crate`
1305 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1306 let vis = VisibilityKind::Crate(CrateSugar::PubCrate);
1307 return Ok(Visibility {
1308 span: lo.to(self.prev_token.span),
1309 kind: vis,
1310 tokens: None,
1311 });
1312 } else if self.is_keyword_ahead(1, &[kw::In]) {
1313 // Parse `pub(in path)`.
1314 self.bump(); // `(`
1315 self.bump(); // `in`
1316 let path = self.parse_path(PathStyle::Mod)?; // `path`
1317 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1318 let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID };
1319 return Ok(Visibility {
1320 span: lo.to(self.prev_token.span),
1321 kind: vis,
1322 tokens: None,
1323 });
1324 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren))
1325 && self.is_keyword_ahead(1, &[kw::Super, kw::SelfLower])
1326 {
1327 // Parse `pub(self)` or `pub(super)`.
1328 self.bump(); // `(`
1329 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
1330 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1331 let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID };
1332 return Ok(Visibility {
1333 span: lo.to(self.prev_token.span),
1334 kind: vis,
1335 tokens: None,
1336 });
1337 } else if let FollowedByType::No = fbt {
1338 // Provide this diagnostic if a type cannot follow;
1339 // in particular, if this is not a tuple struct.
1340 self.recover_incorrect_vis_restriction()?;
1341 // Emit diagnostic, but continue with public visibility.
1342 }
1343 }
1344
1345 Ok(Visibility { span: lo, kind: VisibilityKind::Public, tokens: None })
1346 }
1347
1348 /// Recovery for e.g. `pub(something) fn ...` or `struct X { pub(something) y: Z }`
recover_incorrect_vis_restriction(&mut self) -> PResult<'a, ()>1349 fn recover_incorrect_vis_restriction(&mut self) -> PResult<'a, ()> {
1350 self.bump(); // `(`
1351 let path = self.parse_path(PathStyle::Mod)?;
1352 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1353
1354 let msg = "incorrect visibility restriction";
1355 let suggestion = r##"some possible visibility restrictions are:
1356 `pub(crate)`: visible only on the current crate
1357 `pub(super)`: visible only in the current module's parent
1358 `pub(in path::to::module)`: visible only on the specified path"##;
1359
1360 let path_str = pprust::path_to_string(&path);
1361
1362 struct_span_err!(self.sess.span_diagnostic, path.span, E0704, "{}", msg)
1363 .help(suggestion)
1364 .span_suggestion(
1365 path.span,
1366 &format!("make this visible only to module `{}` with `in`", path_str),
1367 format!("in {}", path_str),
1368 Applicability::MachineApplicable,
1369 )
1370 .emit();
1371
1372 Ok(())
1373 }
1374
1375 /// Parses `extern string_literal?`.
parse_extern(&mut self) -> Extern1376 fn parse_extern(&mut self) -> Extern {
1377 if self.eat_keyword(kw::Extern) { Extern::from_abi(self.parse_abi()) } else { Extern::None }
1378 }
1379
1380 /// Parses a string literal as an ABI spec.
parse_abi(&mut self) -> Option<StrLit>1381 fn parse_abi(&mut self) -> Option<StrLit> {
1382 match self.parse_str_lit() {
1383 Ok(str_lit) => Some(str_lit),
1384 Err(Some(lit)) => match lit.kind {
1385 ast::LitKind::Err(_) => None,
1386 _ => {
1387 self.struct_span_err(lit.span, "non-string ABI literal")
1388 .span_suggestion(
1389 lit.span,
1390 "specify the ABI with a string literal",
1391 "\"C\"".to_string(),
1392 Applicability::MaybeIncorrect,
1393 )
1394 .emit();
1395 None
1396 }
1397 },
1398 Err(None) => None,
1399 }
1400 }
1401
collect_tokens_no_attrs<R: AstLike>( &mut self, f: impl FnOnce(&mut Self) -> PResult<'a, R>, ) -> PResult<'a, R>1402 pub fn collect_tokens_no_attrs<R: AstLike>(
1403 &mut self,
1404 f: impl FnOnce(&mut Self) -> PResult<'a, R>,
1405 ) -> PResult<'a, R> {
1406 // The only reason to call `collect_tokens_no_attrs` is if you want tokens, so use
1407 // `ForceCollect::Yes`
1408 self.collect_tokens_trailing_token(
1409 AttrWrapper::empty(),
1410 ForceCollect::Yes,
1411 |this, _attrs| Ok((f(this)?, TrailingToken::None)),
1412 )
1413 }
1414
1415 /// `::{` or `::*`
is_import_coupler(&mut self) -> bool1416 fn is_import_coupler(&mut self) -> bool {
1417 self.check(&token::ModSep)
1418 && self.look_ahead(1, |t| {
1419 *t == token::OpenDelim(token::Brace) || *t == token::BinOp(token::Star)
1420 })
1421 }
1422
clear_expected_tokens(&mut self)1423 pub fn clear_expected_tokens(&mut self) {
1424 self.expected_tokens.clear();
1425 }
1426 }
1427
make_unclosed_delims_error( unmatched: UnmatchedBrace, sess: &ParseSess, ) -> Option<DiagnosticBuilder<'_>>1428 crate fn make_unclosed_delims_error(
1429 unmatched: UnmatchedBrace,
1430 sess: &ParseSess,
1431 ) -> Option<DiagnosticBuilder<'_>> {
1432 // `None` here means an `Eof` was found. We already emit those errors elsewhere, we add them to
1433 // `unmatched_braces` only for error recovery in the `Parser`.
1434 let found_delim = unmatched.found_delim?;
1435 let span: MultiSpan = if let Some(sp) = unmatched.unclosed_span {
1436 vec![unmatched.found_span, sp].into()
1437 } else {
1438 unmatched.found_span.into()
1439 };
1440 let mut err = sess.span_diagnostic.struct_span_err(
1441 span,
1442 &format!(
1443 "mismatched closing delimiter: `{}`",
1444 pprust::token_kind_to_string(&token::CloseDelim(found_delim)),
1445 ),
1446 );
1447 err.span_label(unmatched.found_span, "mismatched closing delimiter");
1448 if let Some(sp) = unmatched.candidate_span {
1449 err.span_label(sp, "closing delimiter possibly meant for this");
1450 }
1451 if let Some(sp) = unmatched.unclosed_span {
1452 err.span_label(sp, "unclosed delimiter");
1453 }
1454 Some(err)
1455 }
1456
emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &ParseSess)1457 pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &ParseSess) {
1458 *sess.reached_eof.borrow_mut() |=
1459 unclosed_delims.iter().any(|unmatched_delim| unmatched_delim.found_delim.is_none());
1460 for unmatched in unclosed_delims.drain(..) {
1461 if let Some(mut e) = make_unclosed_delims_error(unmatched, sess) {
1462 e.emit();
1463 }
1464 }
1465 }
1466
1467 /// A helper struct used when building an `AttrAnnotatedTokenStream` from
1468 /// a `LazyTokenStream`. Both delimiter and non-delimited tokens
1469 /// are stored as `FlatToken::Token`. A vector of `FlatToken`s
1470 /// is then 'parsed' to build up an `AttrAnnotatedTokenStream` with nested
1471 /// `AttrAnnotatedTokenTree::Delimited` tokens
1472 #[derive(Debug, Clone)]
1473 pub enum FlatToken {
1474 /// A token - this holds both delimiter (e.g. '{' and '}')
1475 /// and non-delimiter tokens
1476 Token(Token),
1477 /// Holds the `AttributesData` for an AST node. The
1478 /// `AttributesData` is inserted directly into the
1479 /// constructed `AttrAnnotatedTokenStream` as
1480 /// an `AttrAnnotatedTokenTree::Attributes`
1481 AttrTarget(AttributesData),
1482 /// A special 'empty' token that is ignored during the conversion
1483 /// to an `AttrAnnotatedTokenStream`. This is used to simplify the
1484 /// handling of replace ranges.
1485 Empty,
1486 }
1487