1 use rustc_target::spec::abi::{self, Abi};
2 use ast::{AngleBracketedArgs, ParenthesisedArgs, AttrStyle, BareFnTy};
3 use ast::{GenericBound, TraitBoundModifier};
5 use ast::{Mod, AnonConst, Arg, Arm, Guard, Attribute, BindingMode, TraitItemKind};
7 use ast::{BlockCheckMode, CaptureBy, Movability};
8 use ast::{Constness, Crate};
11 use ast::{Expr, ExprKind, RangeLimits};
12 use ast::{Field, FnDecl, FnHeader};
13 use ast::{ForeignItem, ForeignItemKind, FunctionRetTy};
14 use ast::{GenericParam, GenericParamKind};
16 use ast::{Ident, ImplItem, IsAsync, IsAuto, Item, ItemKind};
17 use ast::{Label, Lifetime, Lit, LitKind};
19 use ast::MacStmtStyle;
20 use ast::{Mac, Mac_, MacDelimiter};
21 use ast::{MutTy, Mutability};
22 use ast::{Pat, PatKind, PathSegment};
23 use ast::{PolyTraitRef, QSelf};
24 use ast::{Stmt, StmtKind};
25 use ast::{VariantData, StructField};
28 use ast::{TraitItem, TraitRef, TraitObjectSyntax};
29 use ast::{Ty, TyKind, TypeBinding, GenericBounds};
30 use ast::{Visibility, VisibilityKind, WhereClause, CrateSugar};
31 use ast::{UseTree, UseTreeKind};
32 use ast::{BinOpKind, UnOp};
33 use ast::{RangeEnd, RangeSyntax};
35 use ext::base::DummyResult;
36 use source_map::{self, SourceMap, Spanned, respan};
37 use syntax_pos::{self, Span, MultiSpan, BytePos, FileName};
38 use errors::{self, Applicability, DiagnosticBuilder, DiagnosticId};
39 use parse::{self, SeqSep, classify, token};
40 use parse::lexer::TokenAndSpan;
41 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
42 use parse::token::DelimToken;
43 use parse::{new_sub_parser_from_file, ParseSess, Directory, DirectoryOwnership};
44 use util::parser::{AssocOp, Fixity};
49 use tokenstream::{self, DelimSpan, ThinTokenStream, TokenTree, TokenStream};
50 use symbol::{Symbol, keywords};
55 use std::path::{self, Path, PathBuf};
59 /// Whether the type alias or associated type is a concrete type or an existential type
61 /// Just a new name for the same type
63 /// Only trait impls of the type will be usable, not the actual type itself
64 Existential(GenericBounds),
68 struct Restrictions: u8 {
69 const STMT_EXPR = 1 << 0;
70 const NO_STRUCT_LITERAL = 1 << 1;
74 type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>);
76 /// How to parse a path.
77 #[derive(Copy, Clone, PartialEq)]
79 /// In some contexts, notably in expressions, paths with generic arguments are ambiguous
80 /// with something else. For example, in expressions `segment < ....` can be interpreted
81 /// as a comparison and `segment ( ....` can be interpreted as a function call.
82 /// In all such contexts the non-path interpretation is preferred by default for practical
83 /// reasons, but the path interpretation can be forced by the disambiguator `::`, e.g.
84 /// `x<y>` - comparisons, `x::<y>` - unambiguously a path.
86 /// In other contexts, notably in types, no ambiguity exists and paths can be written
87 /// without the disambiguator, e.g., `x<y>` - unambiguously a path.
88 /// Paths with disambiguators are still accepted, `x::<Y>` - unambiguously a path too.
90 /// A path with generic arguments disallowed, e.g., `foo::bar::Baz`, used in imports,
91 /// visibilities or attributes.
92 /// Technically, this variant is unnecessary and e.g., `Expr` can be used instead
93 /// (paths in "mod" contexts have to be checked later for absence of generic arguments
94 /// anyway, due to macros), but it is used to avoid weird suggestions about expected
95 /// tokens when something goes wrong.
99 #[derive(Clone, Copy, PartialEq, Debug)]
105 #[derive(Clone, Copy, PartialEq, Debug)]
111 /// Possibly accept an `token::Interpolated` expression (a pre-parsed expression
112 /// dropped into the token stream, which happens while parsing the result of
113 /// macro expansion). Placement of these is not as complex as I feared it would
114 /// be. The important thing is to make sure that lookahead doesn't balk at
115 /// `token::Interpolated` tokens.
116 macro_rules! maybe_whole_expr {
118 if let token::Interpolated(nt) = $p.token.clone() {
120 token::NtExpr(ref e) | token::NtLiteral(ref e) => {
122 return Ok((*e).clone());
124 token::NtPath(ref path) => {
127 let kind = ExprKind::Path(None, (*path).clone());
128 return Ok($p.mk_expr(span, kind, ThinVec::new()));
130 token::NtBlock(ref block) => {
133 let kind = ExprKind::Block((*block).clone(), None);
134 return Ok($p.mk_expr(span, kind, ThinVec::new()));
142 /// As maybe_whole_expr, but for things other than expressions
143 macro_rules! maybe_whole {
144 ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
145 if let token::Interpolated(nt) = $p.token.clone() {
146 if let token::$constructor($x) = nt.0.clone() {
154 fn maybe_append(mut lhs: Vec<Attribute>, mut rhs: Option<Vec<Attribute>>) -> Vec<Attribute> {
155 if let Some(ref mut rhs) = rhs {
161 #[derive(Debug, Clone, Copy, PartialEq)]
172 trait RecoverQPath: Sized {
173 const PATH_STYLE: PathStyle = PathStyle::Expr;
174 fn to_ty(&self) -> Option<P<Ty>>;
175 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self;
176 fn to_string(&self) -> String;
179 impl RecoverQPath for Ty {
180 const PATH_STYLE: PathStyle = PathStyle::Type;
181 fn to_ty(&self) -> Option<P<Ty>> {
182 Some(P(self.clone()))
184 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self {
185 Self { span: path.span, node: TyKind::Path(qself, path), id: self.id }
187 fn to_string(&self) -> String {
188 pprust::ty_to_string(self)
192 impl RecoverQPath for Pat {
193 fn to_ty(&self) -> Option<P<Ty>> {
196 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self {
197 Self { span: path.span, node: PatKind::Path(qself, path), id: self.id }
199 fn to_string(&self) -> String {
200 pprust::pat_to_string(self)
204 impl RecoverQPath for Expr {
205 fn to_ty(&self) -> Option<P<Ty>> {
208 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self {
209 Self { span: path.span, node: ExprKind::Path(qself, path),
210 id: self.id, attrs: self.attrs.clone() }
212 fn to_string(&self) -> String {
213 pprust::expr_to_string(self)
217 /* ident is handled by common.rs */
220 pub struct Parser<'a> {
221 pub sess: &'a ParseSess,
222 /// the current token:
223 pub token: token::Token,
224 /// the span of the current token:
226 /// the span of the previous token:
227 meta_var_span: Option<Span>,
229 /// the previous token kind
230 prev_token_kind: PrevTokenKind,
231 restrictions: Restrictions,
232 /// Used to determine the path to externally loaded source files
233 crate directory: Directory<'a>,
234 /// Whether to parse sub-modules in other files.
235 pub recurse_into_file_modules: bool,
236 /// Name of the root module this parser originated from. If `None`, then the
237 /// name is not known. This does not change while the parser is descending
238 /// into modules, and sub-parsers have new values for this name.
239 pub root_module_name: Option<String>,
240 crate expected_tokens: Vec<TokenType>,
241 token_cursor: TokenCursor,
242 desugar_doc_comments: bool,
243 /// Whether we should configure out of line modules as we parse.
250 frame: TokenCursorFrame,
251 stack: Vec<TokenCursorFrame>,
255 struct TokenCursorFrame {
256 delim: token::DelimToken,
259 tree_cursor: tokenstream::Cursor,
261 last_token: LastToken,
264 /// This is used in `TokenCursorFrame` above to track tokens that are consumed
265 /// by the parser, and then that's transitively used to record the tokens that
266 /// each parse AST item is created with.
268 /// Right now this has two states, either collecting tokens or not collecting
269 /// tokens. If we're collecting tokens we just save everything off into a local
270 /// `Vec`. This should eventually though likely save tokens from the original
271 /// token stream and just use slicing of token streams to avoid creation of a
272 /// whole new vector.
274 /// The second state is where we're passively not recording tokens, but the last
275 /// token is still tracked for when we want to start recording tokens. This
276 /// "last token" means that when we start recording tokens we'll want to ensure
277 /// that this, the first token, is included in the output.
279 /// You can find some more example usage of this in the `collect_tokens` method
283 Collecting(Vec<TokenStream>),
284 Was(Option<TokenStream>),
287 impl TokenCursorFrame {
288 fn new(sp: DelimSpan, delim: DelimToken, tts: &ThinTokenStream) -> Self {
292 open_delim: delim == token::NoDelim,
293 tree_cursor: tts.stream().into_trees(),
294 close_delim: delim == token::NoDelim,
295 last_token: LastToken::Was(None),
301 fn next(&mut self) -> TokenAndSpan {
303 let tree = if !self.frame.open_delim {
304 self.frame.open_delim = true;
305 TokenTree::open_tt(self.frame.span.open, self.frame.delim)
306 } else if let Some(tree) = self.frame.tree_cursor.next() {
308 } else if !self.frame.close_delim {
309 self.frame.close_delim = true;
310 TokenTree::close_tt(self.frame.span.close, self.frame.delim)
311 } else if let Some(frame) = self.stack.pop() {
315 return TokenAndSpan { tok: token::Eof, sp: syntax_pos::DUMMY_SP }
318 match self.frame.last_token {
319 LastToken::Collecting(ref mut v) => v.push(tree.clone().into()),
320 LastToken::Was(ref mut t) => *t = Some(tree.clone().into()),
324 TokenTree::Token(sp, tok) => return TokenAndSpan { tok: tok, sp: sp },
325 TokenTree::Delimited(sp, delim, tts) => {
326 let frame = TokenCursorFrame::new(sp, delim, &tts);
327 self.stack.push(mem::replace(&mut self.frame, frame));
333 fn next_desugared(&mut self) -> TokenAndSpan {
334 let (sp, name) = match self.next() {
335 TokenAndSpan { sp, tok: token::DocComment(name) } => (sp, name),
339 let stripped = strip_doc_comment_decoration(&name.as_str());
341 // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
342 // required to wrap the text.
343 let mut num_of_hashes = 0;
345 for ch in stripped.chars() {
348 '#' if count > 0 => count + 1,
351 num_of_hashes = cmp::max(num_of_hashes, count);
354 let delim_span = DelimSpan::from_single(sp);
355 let body = TokenTree::Delimited(
358 [TokenTree::Token(sp, token::Ident(ast::Ident::from_str("doc"), false)),
359 TokenTree::Token(sp, token::Eq),
360 TokenTree::Token(sp, token::Literal(
361 token::StrRaw(Symbol::intern(&stripped), num_of_hashes), None))
363 .iter().cloned().collect::<TokenStream>().into(),
366 self.stack.push(mem::replace(&mut self.frame, TokenCursorFrame::new(
369 &if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
370 [TokenTree::Token(sp, token::Pound), TokenTree::Token(sp, token::Not), body]
371 .iter().cloned().collect::<TokenStream>().into()
373 [TokenTree::Token(sp, token::Pound), body]
374 .iter().cloned().collect::<TokenStream>().into()
382 #[derive(Clone, PartialEq)]
383 crate enum TokenType {
385 Keyword(keywords::Keyword),
394 fn to_string(&self) -> String {
396 TokenType::Token(ref t) => format!("`{}`", pprust::token_to_string(t)),
397 TokenType::Keyword(kw) => format!("`{}`", kw.name()),
398 TokenType::Operator => "an operator".to_string(),
399 TokenType::Lifetime => "lifetime".to_string(),
400 TokenType::Ident => "identifier".to_string(),
401 TokenType::Path => "path".to_string(),
402 TokenType::Type => "type".to_string(),
407 /// Returns true if `IDENT t` can start a type - `IDENT::a::b`, `IDENT<u8, u8>`,
408 /// `IDENT<<u8 as Trait>::AssocTy>`.
410 /// Types can also be of the form `IDENT(u8, u8) -> u8`, however this assumes
411 /// that IDENT is not the ident of a fn trait
412 fn can_continue_type_after_non_fn_ident(t: &token::Token) -> bool {
413 t == &token::ModSep || t == &token::Lt ||
414 t == &token::BinOp(token::Shl)
417 /// Information about the path to a module.
418 pub struct ModulePath {
421 pub result: Result<ModulePathSuccess, Error>,
424 pub struct ModulePathSuccess {
426 pub directory_ownership: DirectoryOwnership,
431 FileNotFoundForModule {
433 default_path: String,
434 secondary_path: String,
439 default_path: String,
440 secondary_path: String,
443 InclusiveRangeWithNoEnd,
447 fn span_err<S: Into<MultiSpan>>(self,
449 handler: &errors::Handler) -> DiagnosticBuilder {
451 Error::FileNotFoundForModule { ref mod_name,
455 let mut err = struct_span_err!(handler, sp, E0583,
456 "file not found for module `{}`", mod_name);
457 err.help(&format!("name the file either {} or {} inside the directory \"{}\"",
463 Error::DuplicatePaths { ref mod_name, ref default_path, ref secondary_path } => {
464 let mut err = struct_span_err!(handler, sp, E0584,
465 "file for module `{}` found at both {} and {}",
469 err.help("delete or rename one of them to remove the ambiguity");
472 Error::UselessDocComment => {
473 let mut err = struct_span_err!(handler, sp, E0585,
474 "found a documentation comment that doesn't document anything");
475 err.help("doc comments must come before what they document, maybe a comment was \
476 intended with `//`?");
479 Error::InclusiveRangeWithNoEnd => {
480 let mut err = struct_span_err!(handler, sp, E0586,
481 "inclusive range with no end");
482 err.help("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)");
492 AttributesParsed(ThinVec<Attribute>),
493 AlreadyParsed(P<Expr>),
496 impl From<Option<ThinVec<Attribute>>> for LhsExpr {
497 fn from(o: Option<ThinVec<Attribute>>) -> Self {
498 if let Some(attrs) = o {
499 LhsExpr::AttributesParsed(attrs)
501 LhsExpr::NotYetParsed
506 impl From<P<Expr>> for LhsExpr {
507 fn from(expr: P<Expr>) -> Self {
508 LhsExpr::AlreadyParsed(expr)
512 /// Create a placeholder argument.
513 fn dummy_arg(span: Span) -> Arg {
514 let ident = Ident::new(keywords::Invalid.name(), span);
516 id: ast::DUMMY_NODE_ID,
517 node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), ident, None),
523 id: ast::DUMMY_NODE_ID
525 Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID }
528 #[derive(Copy, Clone, Debug)]
529 enum TokenExpectType {
534 impl<'a> Parser<'a> {
535 pub fn new(sess: &'a ParseSess,
537 directory: Option<Directory<'a>>,
538 recurse_into_file_modules: bool,
539 desugar_doc_comments: bool)
541 let mut parser = Parser {
543 token: token::Whitespace,
544 span: syntax_pos::DUMMY_SP,
545 prev_span: syntax_pos::DUMMY_SP,
547 prev_token_kind: PrevTokenKind::Other,
548 restrictions: Restrictions::empty(),
549 recurse_into_file_modules,
550 directory: Directory {
551 path: Cow::from(PathBuf::new()),
552 ownership: DirectoryOwnership::Owned { relative: None }
554 root_module_name: None,
555 expected_tokens: Vec::new(),
556 token_cursor: TokenCursor {
557 frame: TokenCursorFrame::new(
564 desugar_doc_comments,
568 let tok = parser.next_tok();
569 parser.token = tok.tok;
570 parser.span = tok.sp;
572 if let Some(directory) = directory {
573 parser.directory = directory;
574 } else if !parser.span.is_dummy() {
575 if let FileName::Real(mut path) = sess.source_map().span_to_unmapped_path(parser.span) {
577 parser.directory.path = Cow::from(path);
581 parser.process_potential_macro_variable();
585 fn next_tok(&mut self) -> TokenAndSpan {
586 let mut next = if self.desugar_doc_comments {
587 self.token_cursor.next_desugared()
589 self.token_cursor.next()
591 if next.sp.is_dummy() {
592 // Tweak the location for better diagnostics, but keep syntactic context intact.
593 next.sp = self.prev_span.with_ctxt(next.sp.ctxt());
598 /// Convert the current token to a string using self's reader
599 pub fn this_token_to_string(&self) -> String {
600 pprust::token_to_string(&self.token)
603 fn token_descr(&self) -> Option<&'static str> {
604 Some(match &self.token {
605 t if t.is_special_ident() => "reserved identifier",
606 t if t.is_used_keyword() => "keyword",
607 t if t.is_unused_keyword() => "reserved keyword",
608 token::DocComment(..) => "doc comment",
613 fn this_token_descr(&self) -> String {
614 if let Some(prefix) = self.token_descr() {
615 format!("{} `{}`", prefix, self.this_token_to_string())
617 format!("`{}`", self.this_token_to_string())
621 fn unexpected_last<T>(&self, t: &token::Token) -> PResult<'a, T> {
622 let token_str = pprust::token_to_string(t);
623 Err(self.span_fatal(self.prev_span, &format!("unexpected token: `{}`", token_str)))
626 crate fn unexpected<T>(&mut self) -> PResult<'a, T> {
627 match self.expect_one_of(&[], &[]) {
629 Ok(_) => unreachable!(),
633 /// Expect and consume the token t. Signal an error if
634 /// the next token is not t.
635 pub fn expect(&mut self, t: &token::Token) -> PResult<'a, ()> {
636 if self.expected_tokens.is_empty() {
637 if self.token == *t {
641 let token_str = pprust::token_to_string(t);
642 let this_token_str = self.this_token_descr();
643 let mut err = self.fatal(&format!("expected `{}`, found {}",
647 let sp = if self.token == token::Token::Eof {
648 // EOF, don't want to point at the following char, but rather the last token
651 self.sess.source_map().next_point(self.prev_span)
653 let label_exp = format!("expected `{}`", token_str);
654 let cm = self.sess.source_map();
655 match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) {
656 (Ok(ref a), Ok(ref b)) if a.line == b.line => {
657 // When the spans are in the same line, it means that the only content
658 // between them is whitespace, point only at the found token.
659 err.span_label(self.span, label_exp);
662 err.span_label(sp, label_exp);
663 err.span_label(self.span, "unexpected token");
669 self.expect_one_of(slice::from_ref(t), &[])
673 /// Expect next token to be edible or inedible token. If edible,
674 /// then consume it; if inedible, then return without consuming
675 /// anything. Signal a fatal error if next token is unexpected.
676 pub fn expect_one_of(&mut self,
677 edible: &[token::Token],
678 inedible: &[token::Token]) -> PResult<'a, ()>{
679 fn tokens_to_string(tokens: &[TokenType]) -> String {
680 let mut i = tokens.iter();
681 // This might be a sign we need a connect method on Iterator.
683 .map_or(String::new(), |t| t.to_string());
684 i.enumerate().fold(b, |mut b, (i, a)| {
685 if tokens.len() > 2 && i == tokens.len() - 2 {
687 } else if tokens.len() == 2 && i == tokens.len() - 2 {
692 b.push_str(&a.to_string());
696 if edible.contains(&self.token) {
699 } else if inedible.contains(&self.token) {
700 // leave it in the input
703 let mut expected = edible.iter()
704 .map(|x| TokenType::Token(x.clone()))
705 .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
706 .chain(self.expected_tokens.iter().cloned())
707 .collect::<Vec<_>>();
708 expected.sort_by_cached_key(|x| x.to_string());
710 let expect = tokens_to_string(&expected[..]);
711 let actual = self.this_token_to_string();
712 let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 {
713 let short_expect = if expected.len() > 6 {
714 format!("{} possible tokens", expected.len())
718 (format!("expected one of {}, found `{}`", expect, actual),
719 (self.sess.source_map().next_point(self.prev_span),
720 format!("expected one of {} here", short_expect)))
721 } else if expected.is_empty() {
722 (format!("unexpected token: `{}`", actual),
723 (self.prev_span, "unexpected token after this".to_string()))
725 (format!("expected {}, found `{}`", expect, actual),
726 (self.sess.source_map().next_point(self.prev_span),
727 format!("expected {} here", expect)))
729 let mut err = self.fatal(&msg_exp);
730 if self.token.is_ident_named("and") {
731 err.span_suggestion_short_with_applicability(
733 "use `&&` instead of `and` for the boolean operator",
735 Applicability::MaybeIncorrect,
738 if self.token.is_ident_named("or") {
739 err.span_suggestion_short_with_applicability(
741 "use `||` instead of `or` for the boolean operator",
743 Applicability::MaybeIncorrect,
746 let sp = if self.token == token::Token::Eof {
747 // This is EOF, don't want to point at the following char, but rather the last token
753 let cm = self.sess.source_map();
754 match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) {
755 (Ok(ref a), Ok(ref b)) if a.line == b.line => {
756 // When the spans are in the same line, it means that the only content between
757 // them is whitespace, point at the found token in that case:
759 // X | () => { syntax error };
760 // | ^^^^^ expected one of 8 possible tokens here
762 // instead of having:
764 // X | () => { syntax error };
765 // | -^^^^^ unexpected token
767 // | expected one of 8 possible tokens here
768 err.span_label(self.span, label_exp);
770 _ if self.prev_span == syntax_pos::DUMMY_SP => {
771 // Account for macro context where the previous span might not be
772 // available to avoid incorrect output (#54841).
773 err.span_label(self.span, "unexpected token");
776 err.span_label(sp, label_exp);
777 err.span_label(self.span, "unexpected token");
784 /// returns the span of expr, if it was not interpolated or the span of the interpolated token
785 fn interpolated_or_expr_span(&self,
786 expr: PResult<'a, P<Expr>>)
787 -> PResult<'a, (Span, P<Expr>)> {
789 if self.prev_token_kind == PrevTokenKind::Interpolated {
797 fn expected_ident_found(&self) -> DiagnosticBuilder<'a> {
798 let mut err = self.struct_span_err(self.span,
799 &format!("expected identifier, found {}",
800 self.this_token_descr()));
801 if let token::Ident(ident, false) = &self.token {
802 if ident.is_reserved() && !ident.is_path_segment_keyword() &&
803 ident.name != keywords::Underscore.name()
805 err.span_suggestion_with_applicability(
807 "you can escape reserved keywords to use them as identifiers",
808 format!("r#{}", ident),
809 Applicability::MaybeIncorrect,
813 if let Some(token_descr) = self.token_descr() {
814 err.span_label(self.span, format!("expected identifier, found {}", token_descr));
816 err.span_label(self.span, "expected identifier");
817 if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) {
818 err.span_suggestion_with_applicability(
822 Applicability::MachineApplicable,
829 pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
830 self.parse_ident_common(true)
833 fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
835 token::Ident(ident, _) => {
836 if self.token.is_reserved_ident() {
837 let mut err = self.expected_ident_found();
844 let span = self.span;
846 Ok(Ident::new(ident.name, span))
849 Err(if self.prev_token_kind == PrevTokenKind::DocComment {
850 self.span_fatal_err(self.prev_span, Error::UselessDocComment)
852 self.expected_ident_found()
858 /// Check if the next token is `tok`, and return `true` if so.
860 /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
862 crate fn check(&mut self, tok: &token::Token) -> bool {
863 let is_present = self.token == *tok;
864 if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
868 /// Consume token 'tok' if it exists. Returns true if the given
869 /// token was present, false otherwise.
870 pub fn eat(&mut self, tok: &token::Token) -> bool {
871 let is_present = self.check(tok);
872 if is_present { self.bump() }
876 fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
877 self.expected_tokens.push(TokenType::Keyword(kw));
878 self.token.is_keyword(kw)
881 /// If the next token is the given keyword, eat it and return
882 /// true. Otherwise, return false.
883 pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
884 if self.check_keyword(kw) {
892 fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
893 if self.token.is_keyword(kw) {
901 /// If the given word is not a keyword, signal an error.
902 /// If the next token is not the given word, signal an error.
903 /// Otherwise, eat it.
904 fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> {
905 if !self.eat_keyword(kw) {
912 fn check_ident(&mut self) -> bool {
913 if self.token.is_ident() {
916 self.expected_tokens.push(TokenType::Ident);
921 fn check_path(&mut self) -> bool {
922 if self.token.is_path_start() {
925 self.expected_tokens.push(TokenType::Path);
930 fn check_type(&mut self) -> bool {
931 if self.token.can_begin_type() {
934 self.expected_tokens.push(TokenType::Type);
939 /// Expect and consume a `+`. if `+=` is seen, replace it with a `=`
940 /// and continue. If a `+` is not seen, return false.
942 /// This is using when token splitting += into +.
943 /// See issue 47856 for an example of when this may occur.
944 fn eat_plus(&mut self) -> bool {
945 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
947 token::BinOp(token::Plus) => {
951 token::BinOpEq(token::Plus) => {
952 let span = self.span.with_lo(self.span.lo() + BytePos(1));
953 self.bump_with(token::Eq, span);
961 /// Checks to see if the next token is either `+` or `+=`.
962 /// Otherwise returns false.
963 fn check_plus(&mut self) -> bool {
964 if self.token.is_like_plus() {
968 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
973 /// Expect and consume an `&`. If `&&` is seen, replace it with a single
974 /// `&` and continue. If an `&` is not seen, signal an error.
975 fn expect_and(&mut self) -> PResult<'a, ()> {
976 self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
978 token::BinOp(token::And) => {
983 let span = self.span.with_lo(self.span.lo() + BytePos(1));
984 Ok(self.bump_with(token::BinOp(token::And), span))
986 _ => self.unexpected()
990 /// Expect and consume an `|`. If `||` is seen, replace it with a single
991 /// `|` and continue. If an `|` is not seen, signal an error.
992 fn expect_or(&mut self) -> PResult<'a, ()> {
993 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or)));
995 token::BinOp(token::Or) => {
1000 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1001 Ok(self.bump_with(token::BinOp(token::Or), span))
1003 _ => self.unexpected()
1007 fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
1009 None => {/* everything ok */}
1011 let text = suf.as_str();
1012 if text.is_empty() {
1013 self.span_bug(sp, "found empty literal suffix in Some")
1015 self.span_err(sp, &format!("{} with a suffix is invalid", kind));
1020 /// Attempt to consume a `<`. If `<<` is seen, replace it with a single
1021 /// `<` and continue. If a `<` is not seen, return false.
1023 /// This is meant to be used when parsing generics on a path to get the
1025 fn eat_lt(&mut self) -> bool {
1026 self.expected_tokens.push(TokenType::Token(token::Lt));
1032 token::BinOp(token::Shl) => {
1033 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1034 self.bump_with(token::Lt, span);
1041 fn expect_lt(&mut self) -> PResult<'a, ()> {
1049 /// Expect and consume a GT. if a >> is seen, replace it
1050 /// with a single > and continue. If a GT is not seen,
1051 /// signal an error.
1052 fn expect_gt(&mut self) -> PResult<'a, ()> {
1053 self.expected_tokens.push(TokenType::Token(token::Gt));
1059 token::BinOp(token::Shr) => {
1060 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1061 Ok(self.bump_with(token::Gt, span))
1063 token::BinOpEq(token::Shr) => {
1064 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1065 Ok(self.bump_with(token::Ge, span))
1068 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1069 Ok(self.bump_with(token::Eq, span))
1071 _ => self.unexpected()
1075 /// Eat and discard tokens until one of `kets` is encountered. Respects token trees,
1076 /// passes through any errors encountered. Used for error recovery.
1077 fn eat_to_tokens(&mut self, kets: &[&token::Token]) {
1078 let handler = self.diagnostic();
1080 if let Err(ref mut err) = self.parse_seq_to_before_tokens(kets,
1082 TokenExpectType::Expect,
1083 |p| Ok(p.parse_token_tree())) {
1084 handler.cancel(err);
1088 /// Parse a sequence, including the closing delimiter. The function
1089 /// f must consume tokens until reaching the next separator or
1090 /// closing bracket.
1091 pub fn parse_seq_to_end<T, F>(&mut self,
1095 -> PResult<'a, Vec<T>> where
1096 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1098 let val = self.parse_seq_to_before_end(ket, sep, f)?;
1103 /// Parse a sequence, not including the closing delimiter. The function
1104 /// f must consume tokens until reaching the next separator or
1105 /// closing bracket.
1106 pub fn parse_seq_to_before_end<T, F>(&mut self,
1110 -> PResult<'a, Vec<T>>
1111 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1113 self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
1116 fn parse_seq_to_before_tokens<T, F>(
1118 kets: &[&token::Token],
1120 expect: TokenExpectType,
1122 ) -> PResult<'a, Vec<T>>
1123 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1125 let mut first: bool = true;
1127 while !kets.iter().any(|k| {
1129 TokenExpectType::Expect => self.check(k),
1130 TokenExpectType::NoExpect => self.token == **k,
1134 token::CloseDelim(..) | token::Eof => break,
1137 if let Some(ref t) = sep.sep {
1141 if let Err(mut e) = self.expect(t) {
1142 // Attempt to keep parsing if it was a similar separator
1143 if let Some(ref tokens) = t.similar_tokens() {
1144 if tokens.contains(&self.token) {
1149 // Attempt to keep parsing if it was an omitted separator
1163 if sep.trailing_sep_allowed && kets.iter().any(|k| {
1165 TokenExpectType::Expect => self.check(k),
1166 TokenExpectType::NoExpect => self.token == **k,
1179 /// Parse a sequence, including the closing delimiter. The function
1180 /// f must consume tokens until reaching the next separator or
1181 /// closing bracket.
1182 fn parse_unspanned_seq<T, F>(&mut self,
1187 -> PResult<'a, Vec<T>> where
1188 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1191 let result = self.parse_seq_to_before_end(ket, sep, f)?;
1196 /// Advance the parser by one token
1197 pub fn bump(&mut self) {
1198 if self.prev_token_kind == PrevTokenKind::Eof {
1199 // Bumping after EOF is a bad sign, usually an infinite loop.
1200 self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
1203 self.prev_span = self.meta_var_span.take().unwrap_or(self.span);
1205 // Record last token kind for possible error recovery.
1206 self.prev_token_kind = match self.token {
1207 token::DocComment(..) => PrevTokenKind::DocComment,
1208 token::Comma => PrevTokenKind::Comma,
1209 token::BinOp(token::Plus) => PrevTokenKind::Plus,
1210 token::Interpolated(..) => PrevTokenKind::Interpolated,
1211 token::Eof => PrevTokenKind::Eof,
1212 token::Ident(..) => PrevTokenKind::Ident,
1213 _ => PrevTokenKind::Other,
1216 let next = self.next_tok();
1217 self.span = next.sp;
1218 self.token = next.tok;
1219 self.expected_tokens.clear();
1220 // check after each token
1221 self.process_potential_macro_variable();
1224 /// Advance the parser using provided token as a next one. Use this when
1225 /// consuming a part of a token. For example a single `<` from `<<`.
1226 fn bump_with(&mut self, next: token::Token, span: Span) {
1227 self.prev_span = self.span.with_hi(span.lo());
1228 // It would be incorrect to record the kind of the current token, but
1229 // fortunately for tokens currently using `bump_with`, the
1230 // prev_token_kind will be of no use anyway.
1231 self.prev_token_kind = PrevTokenKind::Other;
1234 self.expected_tokens.clear();
1237 pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where
1238 F: FnOnce(&token::Token) -> R,
1241 return f(&self.token)
1244 f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1245 Some(tree) => match tree {
1246 TokenTree::Token(_, tok) => tok,
1247 TokenTree::Delimited(_, delim, _) => token::OpenDelim(delim),
1249 None => token::CloseDelim(self.token_cursor.frame.delim),
1253 fn look_ahead_span(&self, dist: usize) -> Span {
1258 match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1259 Some(TokenTree::Token(span, _)) => span,
1260 Some(TokenTree::Delimited(span, ..)) => span.entire(),
1261 None => self.look_ahead_span(dist - 1),
1264 pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
1265 self.sess.span_diagnostic.struct_span_fatal(self.span, m)
1267 pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1268 self.sess.span_diagnostic.struct_span_fatal(sp, m)
1270 fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> {
1271 err.span_err(sp, self.diagnostic())
1273 fn bug(&self, m: &str) -> ! {
1274 self.sess.span_diagnostic.span_bug(self.span, m)
1276 fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
1277 self.sess.span_diagnostic.span_err(sp, m)
1279 fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1280 self.sess.span_diagnostic.struct_span_err(sp, m)
1282 crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
1283 self.sess.span_diagnostic.span_bug(sp, m)
1285 crate fn abort_if_errors(&self) {
1286 self.sess.span_diagnostic.abort_if_errors();
1289 fn cancel(&self, err: &mut DiagnosticBuilder) {
1290 self.sess.span_diagnostic.cancel(err)
1293 crate fn diagnostic(&self) -> &'a errors::Handler {
1294 &self.sess.span_diagnostic
1297 /// Is the current token one of the keywords that signals a bare function
1299 fn token_is_bare_fn_keyword(&mut self) -> bool {
1300 self.check_keyword(keywords::Fn) ||
1301 self.check_keyword(keywords::Unsafe) ||
1302 self.check_keyword(keywords::Extern) && self.is_extern_non_path()
1305 /// parse a `TyKind::BareFn` type:
1306 fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
1309 [unsafe] [extern "ABI"] fn (S) -> T
1319 let unsafety = self.parse_unsafety();
1320 let abi = if self.eat_keyword(keywords::Extern) {
1321 self.parse_opt_abi()?.unwrap_or(Abi::C)
1326 self.expect_keyword(keywords::Fn)?;
1327 let (inputs, variadic) = self.parse_fn_args(false, true)?;
1328 let ret_ty = self.parse_ret_ty(false)?;
1329 let decl = P(FnDecl {
1334 Ok(TyKind::BareFn(P(BareFnTy {
1342 /// Parse asyncness: `async` or nothing
1343 fn parse_asyncness(&mut self) -> IsAsync {
1344 if self.eat_keyword(keywords::Async) {
1346 closure_id: ast::DUMMY_NODE_ID,
1347 return_impl_trait_id: ast::DUMMY_NODE_ID,
1354 /// Parse unsafety: `unsafe` or nothing.
1355 fn parse_unsafety(&mut self) -> Unsafety {
1356 if self.eat_keyword(keywords::Unsafe) {
1363 /// Parse the items in a trait declaration
1364 pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> {
1365 maybe_whole!(self, NtTraitItem, |x| x);
1366 let attrs = self.parse_outer_attributes()?;
1367 let (mut item, tokens) = self.collect_tokens(|this| {
1368 this.parse_trait_item_(at_end, attrs)
1370 // See `parse_item` for why this clause is here.
1371 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
1372 item.tokens = Some(tokens);
1377 fn parse_trait_item_(&mut self,
1379 mut attrs: Vec<Attribute>) -> PResult<'a, TraitItem> {
1382 let (name, node, generics) = if self.eat_keyword(keywords::Type) {
1383 self.parse_trait_item_assoc_ty()?
1384 } else if self.is_const_item() {
1385 self.expect_keyword(keywords::Const)?;
1386 let ident = self.parse_ident()?;
1387 self.expect(&token::Colon)?;
1388 let ty = self.parse_ty()?;
1389 let default = if self.eat(&token::Eq) {
1390 let expr = self.parse_expr()?;
1391 self.expect(&token::Semi)?;
1394 self.expect(&token::Semi)?;
1397 (ident, TraitItemKind::Const(ty, default), ast::Generics::default())
1398 } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
1399 // trait item macro.
1400 (keywords::Invalid.ident(), ast::TraitItemKind::Macro(mac), ast::Generics::default())
1402 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
1404 let ident = self.parse_ident()?;
1405 let mut generics = self.parse_generics()?;
1407 let d = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
1408 // This is somewhat dubious; We don't want to allow
1409 // argument names to be left off if there is a
1412 // We don't allow argument names to be left off in edition 2018.
1413 p.parse_arg_general(p.span.rust_2018(), true)
1415 generics.where_clause = self.parse_where_clause()?;
1417 let sig = ast::MethodSig {
1427 let body = match self.token {
1431 debug!("parse_trait_methods(): parsing required method");
1434 token::OpenDelim(token::Brace) => {
1435 debug!("parse_trait_methods(): parsing provided method");
1437 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1438 attrs.extend(inner_attrs.iter().cloned());
1441 token::Interpolated(ref nt) => {
1443 token::NtBlock(..) => {
1445 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1446 attrs.extend(inner_attrs.iter().cloned());
1450 let token_str = self.this_token_descr();
1451 let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
1453 err.span_label(self.span, "expected `;` or `{`");
1459 let token_str = self.this_token_descr();
1460 let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
1462 err.span_label(self.span, "expected `;` or `{`");
1466 (ident, ast::TraitItemKind::Method(sig, body), generics)
1470 id: ast::DUMMY_NODE_ID,
1475 span: lo.to(self.prev_span),
1480 /// Parse optional return type [ -> TY ] in function decl
1481 fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> {
1482 if self.eat(&token::RArrow) {
1483 Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true)?))
1485 Ok(FunctionRetTy::Default(self.span.shrink_to_lo()))
1490 pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
1491 self.parse_ty_common(true, true)
1494 /// Parse a type in restricted contexts where `+` is not permitted.
1495 /// Example 1: `&'a TYPE`
1496 /// `+` is prohibited to maintain operator priority (P(+) < P(&)).
1497 /// Example 2: `value1 as TYPE + value2`
1498 /// `+` is prohibited to avoid interactions with expression grammar.
1499 fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
1500 self.parse_ty_common(false, true)
1503 fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool)
1504 -> PResult<'a, P<Ty>> {
1505 maybe_whole!(self, NtTy, |x| x);
1508 let mut impl_dyn_multi = false;
1509 let node = if self.eat(&token::OpenDelim(token::Paren)) {
1510 // `(TYPE)` is a parenthesized type.
1511 // `(TYPE,)` is a tuple with a single field of type TYPE.
1512 let mut ts = vec![];
1513 let mut last_comma = false;
1514 while self.token != token::CloseDelim(token::Paren) {
1515 ts.push(self.parse_ty()?);
1516 if self.eat(&token::Comma) {
1523 let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
1524 self.expect(&token::CloseDelim(token::Paren))?;
1526 if ts.len() == 1 && !last_comma {
1527 let ty = ts.into_iter().nth(0).unwrap().into_inner();
1528 let maybe_bounds = allow_plus && self.token.is_like_plus();
1530 // `(TY_BOUND_NOPAREN) + BOUND + ...`.
1531 TyKind::Path(None, ref path) if maybe_bounds => {
1532 self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
1534 TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
1535 if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
1536 let path = match bounds[0] {
1537 GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
1538 GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
1540 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1543 _ => TyKind::Paren(P(ty))
1548 } else if self.eat(&token::Not) {
1551 } else if self.eat(&token::BinOp(token::Star)) {
1553 TyKind::Ptr(self.parse_ptr()?)
1554 } else if self.eat(&token::OpenDelim(token::Bracket)) {
1556 let t = self.parse_ty()?;
1557 // Parse optional `; EXPR` in `[TYPE; EXPR]`
1558 let t = match self.maybe_parse_fixed_length_of_vec()? {
1559 None => TyKind::Slice(t),
1560 Some(length) => TyKind::Array(t, AnonConst {
1561 id: ast::DUMMY_NODE_ID,
1565 self.expect(&token::CloseDelim(token::Bracket))?;
1567 } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
1570 self.parse_borrowed_pointee()?
1571 } else if self.eat_keyword_noexpect(keywords::Typeof) {
1573 // In order to not be ambiguous, the type must be surrounded by parens.
1574 self.expect(&token::OpenDelim(token::Paren))?;
1576 id: ast::DUMMY_NODE_ID,
1577 value: self.parse_expr()?,
1579 self.expect(&token::CloseDelim(token::Paren))?;
1581 } else if self.eat_keyword(keywords::Underscore) {
1582 // A type to be inferred `_`
1584 } else if self.token_is_bare_fn_keyword() {
1585 // Function pointer type
1586 self.parse_ty_bare_fn(Vec::new())?
1587 } else if self.check_keyword(keywords::For) {
1588 // Function pointer type or bound list (trait object type) starting with a poly-trait.
1589 // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
1590 // `for<'lt> Trait1<'lt> + Trait2 + 'a`
1592 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
1593 if self.token_is_bare_fn_keyword() {
1594 self.parse_ty_bare_fn(lifetime_defs)?
1596 let path = self.parse_path(PathStyle::Type)?;
1597 let parse_plus = allow_plus && self.check_plus();
1598 self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
1600 } else if self.eat_keyword(keywords::Impl) {
1601 // Always parse bounds greedily for better error recovery.
1602 let bounds = self.parse_generic_bounds()?;
1603 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1604 TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
1605 } else if self.check_keyword(keywords::Dyn) &&
1606 (self.span.rust_2018() ||
1607 self.look_ahead(1, |t| t.can_begin_bound() &&
1608 !can_continue_type_after_non_fn_ident(t))) {
1609 self.bump(); // `dyn`
1610 // Always parse bounds greedily for better error recovery.
1611 let bounds = self.parse_generic_bounds()?;
1612 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1613 TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
1614 } else if self.check(&token::Question) ||
1615 self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
1616 // Bound list (trait object type)
1617 TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus)?,
1618 TraitObjectSyntax::None)
1619 } else if self.eat_lt() {
1621 let (qself, path) = self.parse_qpath(PathStyle::Type)?;
1622 TyKind::Path(Some(qself), path)
1623 } else if self.token.is_path_start() {
1625 let path = self.parse_path(PathStyle::Type)?;
1626 if self.eat(&token::Not) {
1627 // Macro invocation in type position
1628 let (delim, tts) = self.expect_delimited_token_tree()?;
1629 let node = Mac_ { path, tts, delim };
1630 TyKind::Mac(respan(lo.to(self.prev_span), node))
1632 // Just a type path or bound list (trait object type) starting with a trait.
1634 // `Trait1 + Trait2 + 'a`
1635 if allow_plus && self.check_plus() {
1636 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1638 TyKind::Path(None, path)
1642 let msg = format!("expected type, found {}", self.this_token_descr());
1643 return Err(self.fatal(&msg));
1646 let span = lo.to(self.prev_span);
1647 let ty = Ty { node, span, id: ast::DUMMY_NODE_ID };
1649 // Try to recover from use of `+` with incorrect priority.
1650 self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
1651 self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
1652 let ty = self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)?;
1657 fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
1658 lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
1659 let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));
1660 let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
1662 self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
1663 bounds.append(&mut self.parse_generic_bounds()?);
1665 Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
1668 fn maybe_report_ambiguous_plus(&mut self, allow_plus: bool, impl_dyn_multi: bool, ty: &Ty) {
1669 if !allow_plus && impl_dyn_multi {
1670 let sum_with_parens = format!("({})", pprust::ty_to_string(&ty));
1671 self.struct_span_err(ty.span, "ambiguous `+` in a type")
1672 .span_suggestion_with_applicability(
1674 "use parentheses to disambiguate",
1676 Applicability::MachineApplicable
1681 fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> {
1682 // Do not add `+` to expected tokens.
1683 if !allow_plus || !self.token.is_like_plus() {
1688 let bounds = self.parse_generic_bounds()?;
1689 let sum_span = ty.span.to(self.prev_span);
1691 let mut err = struct_span_err!(self.sess.span_diagnostic, sum_span, E0178,
1692 "expected a path on the left-hand side of `+`, not `{}`", pprust::ty_to_string(ty));
1695 TyKind::Rptr(ref lifetime, ref mut_ty) => {
1696 let sum_with_parens = pprust::to_string(|s| {
1697 use print::pprust::PrintState;
1700 s.print_opt_lifetime(lifetime)?;
1701 s.print_mutability(mut_ty.mutbl)?;
1703 s.print_type(&mut_ty.ty)?;
1704 s.print_type_bounds(" +", &bounds)?;
1707 err.span_suggestion_with_applicability(
1709 "try adding parentheses",
1711 Applicability::MachineApplicable
1714 TyKind::Ptr(..) | TyKind::BareFn(..) => {
1715 err.span_label(sum_span, "perhaps you forgot parentheses?");
1718 err.span_label(sum_span, "expected a path");
1725 // Try to recover from associated item paths like `[T]::AssocItem`/`(T, U)::AssocItem`.
1726 fn maybe_recover_from_bad_qpath<T: RecoverQPath>(&mut self, base: T, allow_recovery: bool)
1728 // Do not add `::` to expected tokens.
1729 if !allow_recovery || self.token != token::ModSep {
1732 let ty = match base.to_ty() {
1734 None => return Ok(base),
1737 self.bump(); // `::`
1738 let mut segments = Vec::new();
1739 self.parse_path_segments(&mut segments, T::PATH_STYLE, true)?;
1741 let span = ty.span.to(self.prev_span);
1742 let path_span = span.to(span); // use an empty path since `position` == 0
1743 let recovered = base.to_recovered(
1744 Some(QSelf { ty, path_span, position: 0 }),
1745 ast::Path { segments, span },
1749 .struct_span_err(span, "missing angle brackets in associated item path")
1750 .span_suggestion_with_applicability( // this is a best-effort recovery
1751 span, "try", recovered.to_string(), Applicability::MaybeIncorrect
1757 fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
1758 let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
1759 let mutbl = self.parse_mutability();
1760 let ty = self.parse_ty_no_plus()?;
1761 return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl }));
1764 fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
1765 let mutbl = if self.eat_keyword(keywords::Mut) {
1767 } else if self.eat_keyword(keywords::Const) {
1768 Mutability::Immutable
1770 let span = self.prev_span;
1772 "expected mut or const in raw pointer type (use \
1773 `*mut T` or `*const T` as appropriate)");
1774 Mutability::Immutable
1776 let t = self.parse_ty_no_plus()?;
1777 Ok(MutTy { ty: t, mutbl: mutbl })
1780 fn is_named_argument(&mut self) -> bool {
1781 let offset = match self.token {
1782 token::Interpolated(ref nt) => match nt.0 {
1783 token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
1786 token::BinOp(token::And) | token::AndAnd => 1,
1787 _ if self.token.is_keyword(keywords::Mut) => 1,
1791 self.look_ahead(offset, |t| t.is_ident()) &&
1792 self.look_ahead(offset + 1, |t| t == &token::Colon)
1795 /// Skip unexpected attributes and doc comments in this position and emit an appropriate error.
1796 fn eat_incorrect_doc_comment(&mut self, applied_to: &str) {
1797 if let token::DocComment(_) = self.token {
1798 let mut err = self.diagnostic().struct_span_err(
1800 &format!("documentation comments cannot be applied to {}", applied_to),
1802 err.span_label(self.span, "doc comments are not allowed here");
1805 } else if self.token == token::Pound && self.look_ahead(1, |t| {
1806 *t == token::OpenDelim(token::Bracket)
1809 // Skip every token until next possible arg.
1810 while self.token != token::CloseDelim(token::Bracket) {
1813 let sp = lo.to(self.span);
1815 let mut err = self.diagnostic().struct_span_err(
1817 &format!("attributes cannot be applied to {}", applied_to),
1819 err.span_label(sp, "attributes are not allowed here");
1824 /// This version of parse arg doesn't necessarily require
1825 /// identifier names.
1826 fn parse_arg_general(&mut self, require_name: bool, is_trait_item: bool) -> PResult<'a, Arg> {
1827 maybe_whole!(self, NtArg, |x| x);
1829 if let Ok(Some(_)) = self.parse_self_arg() {
1830 let mut err = self.struct_span_err(self.prev_span,
1831 "unexpected `self` argument in function");
1832 err.span_label(self.prev_span,
1833 "`self` is only valid as the first argument of an associated function");
1837 let (pat, ty) = if require_name || self.is_named_argument() {
1838 debug!("parse_arg_general parse_pat (require_name:{})",
1840 self.eat_incorrect_doc_comment("method arguments");
1841 let pat = self.parse_pat(Some("argument name"))?;
1843 if let Err(mut err) = self.expect(&token::Colon) {
1844 // If we find a pattern followed by an identifier, it could be an (incorrect)
1845 // C-style parameter declaration.
1846 if self.check_ident() && self.look_ahead(1, |t| {
1847 *t == token::Comma || *t == token::CloseDelim(token::Paren)
1849 let ident = self.parse_ident().unwrap();
1850 let span = pat.span.with_hi(ident.span.hi());
1852 err.span_suggestion_with_applicability(
1854 "declare the type after the parameter binding",
1855 String::from("<identifier>: <type>"),
1856 Applicability::HasPlaceholders,
1858 } else if require_name && is_trait_item {
1859 if let PatKind::Ident(_, ident, _) = pat.node {
1860 err.span_suggestion_with_applicability(
1862 "explicitly ignore parameter",
1863 format!("_: {}", ident),
1864 Applicability::MachineApplicable,
1868 err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
1874 self.eat_incorrect_doc_comment("a method argument's type");
1875 (pat, self.parse_ty()?)
1877 debug!("parse_arg_general ident_to_pat");
1878 let parser_snapshot_before_ty = self.clone();
1879 self.eat_incorrect_doc_comment("a method argument's type");
1880 let mut ty = self.parse_ty();
1881 if ty.is_ok() && self.token != token::Comma &&
1882 self.token != token::CloseDelim(token::Paren) {
1883 // This wasn't actually a type, but a pattern looking like a type,
1884 // so we are going to rollback and re-parse for recovery.
1885 ty = self.unexpected();
1889 let ident = Ident::new(keywords::Invalid.name(), self.prev_span);
1891 id: ast::DUMMY_NODE_ID,
1892 node: PatKind::Ident(
1893 BindingMode::ByValue(Mutability::Immutable), ident, None),
1899 // Recover from attempting to parse the argument as a type without pattern.
1901 mem::replace(self, parser_snapshot_before_ty);
1902 let pat = self.parse_pat(Some("argument name"))?;
1903 self.expect(&token::Colon)?;
1904 let ty = self.parse_ty()?;
1906 let mut err = self.diagnostic().struct_span_err_with_code(
1908 "patterns aren't allowed in methods without bodies",
1909 DiagnosticId::Error("E0642".into()),
1911 err.span_suggestion_short_with_applicability(
1913 "give this argument a name or use an underscore to ignore it",
1915 Applicability::MachineApplicable,
1919 // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
1921 node: PatKind::Wild,
1923 id: ast::DUMMY_NODE_ID
1930 Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID })
1933 /// Parse a single function argument
1934 crate fn parse_arg(&mut self) -> PResult<'a, Arg> {
1935 self.parse_arg_general(true, false)
1938 /// Parse an argument in a lambda header e.g., |arg, arg|
1939 fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
1940 let pat = self.parse_pat(Some("argument name"))?;
1941 let t = if self.eat(&token::Colon) {
1945 id: ast::DUMMY_NODE_ID,
1946 node: TyKind::Infer,
1947 span: self.prev_span,
1953 id: ast::DUMMY_NODE_ID
1957 fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
1958 if self.eat(&token::Semi) {
1959 Ok(Some(self.parse_expr()?))
1965 /// Matches token_lit = LIT_INTEGER | ...
1966 fn parse_lit_token(&mut self) -> PResult<'a, LitKind> {
1967 let out = match self.token {
1968 token::Interpolated(ref nt) => match nt.0 {
1969 token::NtExpr(ref v) | token::NtLiteral(ref v) => match v.node {
1970 ExprKind::Lit(ref lit) => { lit.node.clone() }
1971 _ => { return self.unexpected_last(&self.token); }
1973 _ => { return self.unexpected_last(&self.token); }
1975 token::Literal(lit, suf) => {
1976 let diag = Some((self.span, &self.sess.span_diagnostic));
1977 let (suffix_illegal, result) = parse::lit_token(lit, suf, diag);
1981 self.expect_no_suffix(sp, lit.literal_name(), suf)
1986 _ => { return self.unexpected_last(&self.token); }
1993 /// Matches lit = true | false | token_lit
1994 crate fn parse_lit(&mut self) -> PResult<'a, Lit> {
1996 let lit = if self.eat_keyword(keywords::True) {
1998 } else if self.eat_keyword(keywords::False) {
1999 LitKind::Bool(false)
2001 let lit = self.parse_lit_token()?;
2004 Ok(source_map::Spanned { node: lit, span: lo.to(self.prev_span) })
2007 /// matches '-' lit | lit (cf. ast_validation::AstValidator::check_expr_within_pat)
2008 crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
2009 maybe_whole_expr!(self);
2011 let minus_lo = self.span;
2012 let minus_present = self.eat(&token::BinOp(token::Minus));
2014 let literal = self.parse_lit()?;
2015 let hi = self.prev_span;
2016 let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
2019 let minus_hi = self.prev_span;
2020 let unary = self.mk_unary(UnOp::Neg, expr);
2021 Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
2027 fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
2029 token::Ident(ident, _) if self.token.is_path_segment_keyword() => {
2030 let span = self.span;
2032 Ok(Ident::new(ident.name, span))
2034 _ => self.parse_ident(),
2038 fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
2040 token::Ident(ident, false) if ident.name == keywords::Underscore.name() => {
2041 let span = self.span;
2043 Ok(Ident::new(ident.name, span))
2045 _ => self.parse_ident(),
2049 /// Parses qualified path.
2050 /// Assumes that the leading `<` has been parsed already.
2052 /// `qualified_path = <type [as trait_ref]>::path`
2057 /// `<T as U>::F::a<S>` (without disambiguator)
2058 /// `<T as U>::F::a::<S>` (with disambiguator)
2059 fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::Path)> {
2060 let lo = self.prev_span;
2061 let ty = self.parse_ty()?;
2063 // `path` will contain the prefix of the path up to the `>`,
2064 // if any (e.g., `U` in the `<T as U>::*` examples
2065 // above). `path_span` has the span of that path, or an empty
2066 // span in the case of something like `<T>::Bar`.
2067 let (mut path, path_span);
2068 if self.eat_keyword(keywords::As) {
2069 let path_lo = self.span;
2070 path = self.parse_path(PathStyle::Type)?;
2071 path_span = path_lo.to(self.prev_span);
2073 path = ast::Path { segments: Vec::new(), span: syntax_pos::DUMMY_SP };
2074 path_span = self.span.to(self.span);
2077 self.expect(&token::Gt)?;
2078 self.expect(&token::ModSep)?;
2080 let qself = QSelf { ty, path_span, position: path.segments.len() };
2081 self.parse_path_segments(&mut path.segments, style, true)?;
2083 Ok((qself, ast::Path { segments: path.segments, span: lo.to(self.prev_span) }))
2086 /// Parses simple paths.
2088 /// `path = [::] segment+`
2089 /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
2092 /// `a::b::C<D>` (without disambiguator)
2093 /// `a::b::C::<D>` (with disambiguator)
2094 /// `Fn(Args)` (without disambiguator)
2095 /// `Fn::(Args)` (with disambiguator)
2096 pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2097 self.parse_path_common(style, true)
2100 crate fn parse_path_common(&mut self, style: PathStyle, enable_warning: bool)
2101 -> PResult<'a, ast::Path> {
2102 maybe_whole!(self, NtPath, |path| {
2103 if style == PathStyle::Mod &&
2104 path.segments.iter().any(|segment| segment.args.is_some()) {
2105 self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
2110 let lo = self.meta_var_span.unwrap_or(self.span);
2111 let mut segments = Vec::new();
2112 let mod_sep_ctxt = self.span.ctxt();
2113 if self.eat(&token::ModSep) {
2114 segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
2116 self.parse_path_segments(&mut segments, style, enable_warning)?;
2118 Ok(ast::Path { segments, span: lo.to(self.prev_span) })
2121 /// Like `parse_path`, but also supports parsing `Word` meta items into paths for back-compat.
2122 /// This is used when parsing derive macro paths in `#[derive]` attributes.
2123 pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2124 let meta_ident = match self.token {
2125 token::Interpolated(ref nt) => match nt.0 {
2126 token::NtMeta(ref meta) => match meta.node {
2127 ast::MetaItemKind::Word => Some(meta.ident.clone()),
2134 if let Some(path) = meta_ident {
2138 self.parse_path(style)
2141 fn parse_path_segments(&mut self,
2142 segments: &mut Vec<PathSegment>,
2144 enable_warning: bool)
2145 -> PResult<'a, ()> {
2147 segments.push(self.parse_path_segment(style, enable_warning)?);
2149 if self.is_import_coupler() || !self.eat(&token::ModSep) {
2155 fn parse_path_segment(&mut self, style: PathStyle, enable_warning: bool)
2156 -> PResult<'a, PathSegment> {
2157 let ident = self.parse_path_segment_ident()?;
2159 let is_args_start = |token: &token::Token| match *token {
2160 token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren) => true,
2163 let check_args_start = |this: &mut Self| {
2164 this.expected_tokens.extend_from_slice(
2165 &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
2167 is_args_start(&this.token)
2170 Ok(if style == PathStyle::Type && check_args_start(self) ||
2171 style != PathStyle::Mod && self.check(&token::ModSep)
2172 && self.look_ahead(1, |t| is_args_start(t)) {
2173 // Generic arguments are found - `<`, `(`, `::<` or `::(`.
2175 if self.eat(&token::ModSep) && style == PathStyle::Type && enable_warning {
2176 self.diagnostic().struct_span_warn(self.prev_span, "unnecessary path disambiguator")
2177 .span_label(self.prev_span, "try removing `::`").emit();
2180 let args = if self.eat_lt() {
2182 let (args, bindings) = self.parse_generic_args()?;
2184 let span = lo.to(self.prev_span);
2185 AngleBracketedArgs { args, bindings, span }.into()
2189 let inputs = self.parse_seq_to_before_tokens(
2190 &[&token::CloseDelim(token::Paren)],
2191 SeqSep::trailing_allowed(token::Comma),
2192 TokenExpectType::Expect,
2195 let span = lo.to(self.prev_span);
2196 let output = if self.eat(&token::RArrow) {
2197 Some(self.parse_ty_common(false, false)?)
2201 ParenthesisedArgs { inputs, output, span }.into()
2204 PathSegment { ident, args, id: ast::DUMMY_NODE_ID }
2206 // Generic arguments are not found.
2207 PathSegment::from_ident(ident)
2211 crate fn check_lifetime(&mut self) -> bool {
2212 self.expected_tokens.push(TokenType::Lifetime);
2213 self.token.is_lifetime()
2216 /// Parse single lifetime 'a or panic.
2217 crate fn expect_lifetime(&mut self) -> Lifetime {
2218 if let Some(ident) = self.token.lifetime() {
2219 let span = self.span;
2221 Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
2223 self.span_bug(self.span, "not a lifetime")
2227 fn eat_label(&mut self) -> Option<Label> {
2228 if let Some(ident) = self.token.lifetime() {
2229 let span = self.span;
2231 Some(Label { ident: Ident::new(ident.name, span) })
2237 /// Parse mutability (`mut` or nothing).
2238 fn parse_mutability(&mut self) -> Mutability {
2239 if self.eat_keyword(keywords::Mut) {
2242 Mutability::Immutable
2246 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
2247 if let token::Literal(token::Integer(name), None) = self.token {
2249 Ok(Ident::new(name, self.prev_span))
2251 self.parse_ident_common(false)
2255 /// Parse ident (COLON expr)?
2256 fn parse_field(&mut self) -> PResult<'a, Field> {
2257 let attrs = self.parse_outer_attributes()?;
2260 // Check if a colon exists one ahead. This means we're parsing a fieldname.
2261 let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
2262 let fieldname = self.parse_field_name()?;
2264 (fieldname, self.parse_expr()?, false)
2266 let fieldname = self.parse_ident_common(false)?;
2268 // Mimic `x: x` for the `x` field shorthand.
2269 let path = ast::Path::from_ident(fieldname);
2270 let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
2271 (fieldname, expr, true)
2275 span: lo.to(expr.span),
2278 attrs: attrs.into(),
2282 fn mk_expr(&mut self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
2283 P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID })
2286 fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
2287 ExprKind::Unary(unop, expr)
2290 fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2291 ExprKind::Binary(binop, lhs, rhs)
2294 fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
2295 ExprKind::Call(f, args)
2298 fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
2299 ExprKind::Index(expr, idx)
2302 fn mk_range(&mut self,
2303 start: Option<P<Expr>>,
2304 end: Option<P<Expr>>,
2305 limits: RangeLimits)
2306 -> PResult<'a, ast::ExprKind> {
2307 if end.is_none() && limits == RangeLimits::Closed {
2308 Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd))
2310 Ok(ExprKind::Range(start, end, limits))
2314 fn mk_assign_op(&mut self, binop: ast::BinOp,
2315 lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2316 ExprKind::AssignOp(binop, lhs, rhs)
2319 pub fn mk_mac_expr(&mut self, span: Span, m: Mac_, attrs: ThinVec<Attribute>) -> P<Expr> {
2321 id: ast::DUMMY_NODE_ID,
2322 node: ExprKind::Mac(source_map::Spanned {node: m, span: span}),
2328 fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, ThinTokenStream)> {
2329 let delim = match self.token {
2330 token::OpenDelim(delim) => delim,
2332 let msg = "expected open delimiter";
2333 let mut err = self.fatal(msg);
2334 err.span_label(self.span, msg);
2338 let tts = match self.parse_token_tree() {
2339 TokenTree::Delimited(_, _, tts) => tts,
2340 _ => unreachable!(),
2342 let delim = match delim {
2343 token::Paren => MacDelimiter::Parenthesis,
2344 token::Bracket => MacDelimiter::Bracket,
2345 token::Brace => MacDelimiter::Brace,
2346 token::NoDelim => self.bug("unexpected no delimiter"),
2348 Ok((delim, tts.stream().into()))
2351 /// At the bottom (top?) of the precedence hierarchy,
2352 /// parse things like parenthesized exprs,
2353 /// macros, return, etc.
2355 /// N.B., this does not parse outer attributes,
2356 /// and is private because it only works
2357 /// correctly if called from parse_dot_or_call_expr().
2358 fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
2359 maybe_whole_expr!(self);
2361 // Outer attributes are already parsed and will be
2362 // added to the return value after the fact.
2364 // Therefore, prevent sub-parser from parsing
2365 // attributes by giving them a empty "already parsed" list.
2366 let mut attrs = ThinVec::new();
2369 let mut hi = self.span;
2373 // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2375 token::OpenDelim(token::Paren) => {
2378 attrs.extend(self.parse_inner_attributes()?);
2380 // (e) is parenthesized e
2381 // (e,) is a tuple with only one field, e
2382 let mut es = vec![];
2383 let mut trailing_comma = false;
2384 while self.token != token::CloseDelim(token::Paren) {
2385 es.push(self.parse_expr()?);
2386 self.expect_one_of(&[], &[token::Comma, token::CloseDelim(token::Paren)])?;
2387 if self.eat(&token::Comma) {
2388 trailing_comma = true;
2390 trailing_comma = false;
2396 hi = self.prev_span;
2397 ex = if es.len() == 1 && !trailing_comma {
2398 ExprKind::Paren(es.into_iter().nth(0).unwrap())
2403 token::OpenDelim(token::Brace) => {
2404 return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
2406 token::BinOp(token::Or) | token::OrOr => {
2407 return self.parse_lambda_expr(attrs);
2409 token::OpenDelim(token::Bracket) => {
2412 attrs.extend(self.parse_inner_attributes()?);
2414 if self.eat(&token::CloseDelim(token::Bracket)) {
2416 ex = ExprKind::Array(Vec::new());
2419 let first_expr = self.parse_expr()?;
2420 if self.eat(&token::Semi) {
2421 // Repeating array syntax: [ 0; 512 ]
2422 let count = AnonConst {
2423 id: ast::DUMMY_NODE_ID,
2424 value: self.parse_expr()?,
2426 self.expect(&token::CloseDelim(token::Bracket))?;
2427 ex = ExprKind::Repeat(first_expr, count);
2428 } else if self.eat(&token::Comma) {
2429 // Vector with two or more elements.
2430 let remaining_exprs = self.parse_seq_to_end(
2431 &token::CloseDelim(token::Bracket),
2432 SeqSep::trailing_allowed(token::Comma),
2433 |p| Ok(p.parse_expr()?)
2435 let mut exprs = vec![first_expr];
2436 exprs.extend(remaining_exprs);
2437 ex = ExprKind::Array(exprs);
2439 // Vector with one element.
2440 self.expect(&token::CloseDelim(token::Bracket))?;
2441 ex = ExprKind::Array(vec![first_expr]);
2444 hi = self.prev_span;
2448 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
2450 return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
2452 if self.span.rust_2018() && self.check_keyword(keywords::Async)
2454 if self.is_async_block() { // check for `async {` and `async move {`
2455 return self.parse_async_block(attrs);
2457 return self.parse_lambda_expr(attrs);
2460 if self.check_keyword(keywords::Move) || self.check_keyword(keywords::Static) {
2461 return self.parse_lambda_expr(attrs);
2463 if self.eat_keyword(keywords::If) {
2464 return self.parse_if_expr(attrs);
2466 if self.eat_keyword(keywords::For) {
2467 let lo = self.prev_span;
2468 return self.parse_for_expr(None, lo, attrs);
2470 if self.eat_keyword(keywords::While) {
2471 let lo = self.prev_span;
2472 return self.parse_while_expr(None, lo, attrs);
2474 if let Some(label) = self.eat_label() {
2475 let lo = label.ident.span;
2476 self.expect(&token::Colon)?;
2477 if self.eat_keyword(keywords::While) {
2478 return self.parse_while_expr(Some(label), lo, attrs)
2480 if self.eat_keyword(keywords::For) {
2481 return self.parse_for_expr(Some(label), lo, attrs)
2483 if self.eat_keyword(keywords::Loop) {
2484 return self.parse_loop_expr(Some(label), lo, attrs)
2486 if self.token == token::OpenDelim(token::Brace) {
2487 return self.parse_block_expr(Some(label),
2489 BlockCheckMode::Default,
2492 let msg = "expected `while`, `for`, `loop` or `{` after a label";
2493 let mut err = self.fatal(msg);
2494 err.span_label(self.span, msg);
2497 if self.eat_keyword(keywords::Loop) {
2498 let lo = self.prev_span;
2499 return self.parse_loop_expr(None, lo, attrs);
2501 if self.eat_keyword(keywords::Continue) {
2502 let label = self.eat_label();
2503 let ex = ExprKind::Continue(label);
2504 let hi = self.prev_span;
2505 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2507 if self.eat_keyword(keywords::Match) {
2508 let match_sp = self.prev_span;
2509 return self.parse_match_expr(attrs).map_err(|mut err| {
2510 err.span_label(match_sp, "while parsing this match expression");
2514 if self.eat_keyword(keywords::Unsafe) {
2515 return self.parse_block_expr(
2518 BlockCheckMode::Unsafe(ast::UserProvided),
2521 if self.is_do_catch_block() {
2522 let mut db = self.fatal("found removed `do catch` syntax");
2523 db.help("Following RFC #2388, the new non-placeholder syntax is `try`");
2526 if self.is_try_block() {
2528 assert!(self.eat_keyword(keywords::Try));
2529 return self.parse_try_block(lo, attrs);
2531 if self.eat_keyword(keywords::Return) {
2532 if self.token.can_begin_expr() {
2533 let e = self.parse_expr()?;
2535 ex = ExprKind::Ret(Some(e));
2537 ex = ExprKind::Ret(None);
2539 } else if self.eat_keyword(keywords::Break) {
2540 let label = self.eat_label();
2541 let e = if self.token.can_begin_expr()
2542 && !(self.token == token::OpenDelim(token::Brace)
2543 && self.restrictions.contains(
2544 Restrictions::NO_STRUCT_LITERAL)) {
2545 Some(self.parse_expr()?)
2549 ex = ExprKind::Break(label, e);
2550 hi = self.prev_span;
2551 } else if self.eat_keyword(keywords::Yield) {
2552 if self.token.can_begin_expr() {
2553 let e = self.parse_expr()?;
2555 ex = ExprKind::Yield(Some(e));
2557 ex = ExprKind::Yield(None);
2559 } else if self.token.is_keyword(keywords::Let) {
2560 // Catch this syntax error here, instead of in `parse_ident`, so
2561 // that we can explicitly mention that let is not to be used as an expression
2562 let mut db = self.fatal("expected expression, found statement (`let`)");
2563 db.span_label(self.span, "expected expression");
2564 db.note("variable declaration using `let` is a statement");
2566 } else if self.token.is_path_start() {
2567 let pth = self.parse_path(PathStyle::Expr)?;
2569 // `!`, as an operator, is prefix, so we know this isn't that
2570 if self.eat(&token::Not) {
2571 // MACRO INVOCATION expression
2572 let (delim, tts) = self.expect_delimited_token_tree()?;
2573 let hi = self.prev_span;
2574 let node = Mac_ { path: pth, tts, delim };
2575 return Ok(self.mk_mac_expr(lo.to(hi), node, attrs))
2577 if self.check(&token::OpenDelim(token::Brace)) {
2578 // This is a struct literal, unless we're prohibited
2579 // from parsing struct literals here.
2580 let prohibited = self.restrictions.contains(
2581 Restrictions::NO_STRUCT_LITERAL
2584 return self.parse_struct_expr(lo, pth, attrs);
2589 ex = ExprKind::Path(None, pth);
2591 match self.parse_literal_maybe_minus() {
2594 ex = expr.node.clone();
2597 self.cancel(&mut err);
2598 let msg = format!("expected expression, found {}",
2599 self.this_token_descr());
2600 let mut err = self.fatal(&msg);
2601 err.span_label(self.span, "expected expression");
2609 let expr = Expr { node: ex, span: lo.to(hi), id: ast::DUMMY_NODE_ID, attrs };
2610 let expr = self.maybe_recover_from_bad_qpath(expr, true)?;
2615 fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Attribute>)
2616 -> PResult<'a, P<Expr>> {
2617 let struct_sp = lo.to(self.prev_span);
2619 let mut fields = Vec::new();
2620 let mut base = None;
2622 attrs.extend(self.parse_inner_attributes()?);
2624 while self.token != token::CloseDelim(token::Brace) {
2625 if self.eat(&token::DotDot) {
2626 let exp_span = self.prev_span;
2627 match self.parse_expr() {
2633 self.recover_stmt();
2636 if self.token == token::Comma {
2637 let mut err = self.sess.span_diagnostic.mut_span_err(
2638 exp_span.to(self.prev_span),
2639 "cannot use a comma after the base struct",
2641 err.span_suggestion_short_with_applicability(
2643 "remove this comma",
2645 Applicability::MachineApplicable
2647 err.note("the base struct must always be the last field");
2649 self.recover_stmt();
2654 match self.parse_field() {
2655 Ok(f) => fields.push(f),
2657 e.span_label(struct_sp, "while parsing this struct");
2660 // If the next token is a comma, then try to parse
2661 // what comes next as additional fields, rather than
2662 // bailing out until next `}`.
2663 if self.token != token::Comma {
2664 self.recover_stmt();
2670 match self.expect_one_of(&[token::Comma],
2671 &[token::CloseDelim(token::Brace)]) {
2675 self.recover_stmt();
2681 let span = lo.to(self.span);
2682 self.expect(&token::CloseDelim(token::Brace))?;
2683 return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
2686 fn parse_or_use_outer_attributes(&mut self,
2687 already_parsed_attrs: Option<ThinVec<Attribute>>)
2688 -> PResult<'a, ThinVec<Attribute>> {
2689 if let Some(attrs) = already_parsed_attrs {
2692 self.parse_outer_attributes().map(|a| a.into())
2696 /// Parse a block or unsafe block
2697 fn parse_block_expr(&mut self, opt_label: Option<Label>,
2698 lo: Span, blk_mode: BlockCheckMode,
2699 outer_attrs: ThinVec<Attribute>)
2700 -> PResult<'a, P<Expr>> {
2701 self.expect(&token::OpenDelim(token::Brace))?;
2703 let mut attrs = outer_attrs;
2704 attrs.extend(self.parse_inner_attributes()?);
2706 let blk = self.parse_block_tail(lo, blk_mode)?;
2707 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs));
2710 /// parse a.b or a(13) or a[4] or just a
2711 fn parse_dot_or_call_expr(&mut self,
2712 already_parsed_attrs: Option<ThinVec<Attribute>>)
2713 -> PResult<'a, P<Expr>> {
2714 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2716 let b = self.parse_bottom_expr();
2717 let (span, b) = self.interpolated_or_expr_span(b)?;
2718 self.parse_dot_or_call_expr_with(b, span, attrs)
2721 fn parse_dot_or_call_expr_with(&mut self,
2724 mut attrs: ThinVec<Attribute>)
2725 -> PResult<'a, P<Expr>> {
2726 // Stitch the list of outer attributes onto the return value.
2727 // A little bit ugly, but the best way given the current code
2729 self.parse_dot_or_call_expr_with_(e0, lo)
2731 expr.map(|mut expr| {
2732 attrs.extend::<Vec<_>>(expr.attrs.into());
2735 ExprKind::If(..) | ExprKind::IfLet(..) => {
2736 if !expr.attrs.is_empty() {
2737 // Just point to the first attribute in there...
2738 let span = expr.attrs[0].span;
2741 "attributes are not yet allowed on `if` \
2752 // Assuming we have just parsed `.`, continue parsing into an expression.
2753 fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2754 let segment = self.parse_path_segment(PathStyle::Expr, true)?;
2755 Ok(match self.token {
2756 token::OpenDelim(token::Paren) => {
2757 // Method call `expr.f()`
2758 let mut args = self.parse_unspanned_seq(
2759 &token::OpenDelim(token::Paren),
2760 &token::CloseDelim(token::Paren),
2761 SeqSep::trailing_allowed(token::Comma),
2762 |p| Ok(p.parse_expr()?)
2764 args.insert(0, self_arg);
2766 let span = lo.to(self.prev_span);
2767 self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
2770 // Field access `expr.f`
2771 if let Some(args) = segment.args {
2772 self.span_err(args.span(),
2773 "field expressions may not have generic arguments");
2776 let span = lo.to(self.prev_span);
2777 self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
2782 fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2787 while self.eat(&token::Question) {
2788 let hi = self.prev_span;
2789 e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
2793 if self.eat(&token::Dot) {
2795 token::Ident(..) => {
2796 e = self.parse_dot_suffix(e, lo)?;
2798 token::Literal(token::Integer(name), _) => {
2799 let span = self.span;
2801 let field = ExprKind::Field(e, Ident::new(name, span));
2802 e = self.mk_expr(lo.to(span), field, ThinVec::new());
2804 token::Literal(token::Float(n), _suf) => {
2806 let fstr = n.as_str();
2807 let mut err = self.diagnostic()
2808 .struct_span_err(self.prev_span, &format!("unexpected token: `{}`", n));
2809 err.span_label(self.prev_span, "unexpected token");
2810 if fstr.chars().all(|x| "0123456789.".contains(x)) {
2811 let float = match fstr.parse::<f64>().ok() {
2815 let sugg = pprust::to_string(|s| {
2816 use print::pprust::PrintState;
2820 s.print_usize(float.trunc() as usize)?;
2823 s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
2825 err.span_suggestion_with_applicability(
2826 lo.to(self.prev_span),
2827 "try parenthesizing the first index",
2829 Applicability::MachineApplicable
2836 // FIXME Could factor this out into non_fatal_unexpected or something.
2837 let actual = self.this_token_to_string();
2838 self.span_err(self.span, &format!("unexpected token: `{}`", actual));
2843 if self.expr_is_complete(&e) { break; }
2846 token::OpenDelim(token::Paren) => {
2847 let es = self.parse_unspanned_seq(
2848 &token::OpenDelim(token::Paren),
2849 &token::CloseDelim(token::Paren),
2850 SeqSep::trailing_allowed(token::Comma),
2851 |p| Ok(p.parse_expr()?)
2853 hi = self.prev_span;
2855 let nd = self.mk_call(e, es);
2856 e = self.mk_expr(lo.to(hi), nd, ThinVec::new());
2860 // Could be either an index expression or a slicing expression.
2861 token::OpenDelim(token::Bracket) => {
2863 let ix = self.parse_expr()?;
2865 self.expect(&token::CloseDelim(token::Bracket))?;
2866 let index = self.mk_index(e, ix);
2867 e = self.mk_expr(lo.to(hi), index, ThinVec::new())
2875 crate fn process_potential_macro_variable(&mut self) {
2876 let (token, span) = match self.token {
2877 token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
2878 self.look_ahead(1, |t| t.is_ident()) => {
2880 let name = match self.token {
2881 token::Ident(ident, _) => ident,
2884 let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
2885 err.span_label(self.span, "unknown macro variable");
2890 token::Interpolated(ref nt) => {
2891 self.meta_var_span = Some(self.span);
2892 // Interpolated identifier and lifetime tokens are replaced with usual identifier
2893 // and lifetime tokens, so the former are never encountered during normal parsing.
2895 token::NtIdent(ident, is_raw) => (token::Ident(ident, is_raw), ident.span),
2896 token::NtLifetime(ident) => (token::Lifetime(ident), ident.span),
2906 /// parse a single token tree from the input.
2907 crate fn parse_token_tree(&mut self) -> TokenTree {
2909 token::OpenDelim(..) => {
2910 let frame = mem::replace(&mut self.token_cursor.frame,
2911 self.token_cursor.stack.pop().unwrap());
2912 self.span = frame.span.entire();
2914 TokenTree::Delimited(
2917 frame.tree_cursor.original_stream().into(),
2920 token::CloseDelim(_) | token::Eof => unreachable!(),
2922 let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span);
2924 TokenTree::Token(span, token)
2929 // parse a stream of tokens into a list of TokenTree's,
2931 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
2932 let mut tts = Vec::new();
2933 while self.token != token::Eof {
2934 tts.push(self.parse_token_tree());
2939 pub fn parse_tokens(&mut self) -> TokenStream {
2940 let mut result = Vec::new();
2943 token::Eof | token::CloseDelim(..) => break,
2944 _ => result.push(self.parse_token_tree().into()),
2947 TokenStream::new(result)
2950 /// Parse a prefix-unary-operator expr
2951 fn parse_prefix_expr(&mut self,
2952 already_parsed_attrs: Option<ThinVec<Attribute>>)
2953 -> PResult<'a, P<Expr>> {
2954 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2956 // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2957 let (hi, ex) = match self.token {
2960 let e = self.parse_prefix_expr(None);
2961 let (span, e) = self.interpolated_or_expr_span(e)?;
2962 (lo.to(span), self.mk_unary(UnOp::Not, e))
2964 // Suggest `!` for bitwise negation when encountering a `~`
2967 let e = self.parse_prefix_expr(None);
2968 let (span, e) = self.interpolated_or_expr_span(e)?;
2969 let span_of_tilde = lo;
2970 let mut err = self.diagnostic()
2971 .struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator");
2972 err.span_suggestion_short_with_applicability(
2974 "use `!` to perform bitwise negation",
2976 Applicability::MachineApplicable
2979 (lo.to(span), self.mk_unary(UnOp::Not, e))
2981 token::BinOp(token::Minus) => {
2983 let e = self.parse_prefix_expr(None);
2984 let (span, e) = self.interpolated_or_expr_span(e)?;
2985 (lo.to(span), self.mk_unary(UnOp::Neg, e))
2987 token::BinOp(token::Star) => {
2989 let e = self.parse_prefix_expr(None);
2990 let (span, e) = self.interpolated_or_expr_span(e)?;
2991 (lo.to(span), self.mk_unary(UnOp::Deref, e))
2993 token::BinOp(token::And) | token::AndAnd => {
2995 let m = self.parse_mutability();
2996 let e = self.parse_prefix_expr(None);
2997 let (span, e) = self.interpolated_or_expr_span(e)?;
2998 (lo.to(span), ExprKind::AddrOf(m, e))
3000 token::Ident(..) if self.token.is_keyword(keywords::In) => {
3002 let place = self.parse_expr_res(
3003 Restrictions::NO_STRUCT_LITERAL,
3006 let blk = self.parse_block()?;
3007 let span = blk.span;
3008 let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new());
3009 (lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr))
3011 token::Ident(..) if self.token.is_keyword(keywords::Box) => {
3013 let e = self.parse_prefix_expr(None);
3014 let (span, e) = self.interpolated_or_expr_span(e)?;
3015 (lo.to(span), ExprKind::Box(e))
3017 token::Ident(..) if self.token.is_ident_named("not") => {
3018 // `not` is just an ordinary identifier in Rust-the-language,
3019 // but as `rustc`-the-compiler, we can issue clever diagnostics
3020 // for confused users who really want to say `!`
3021 let token_cannot_continue_expr = |t: &token::Token| match *t {
3022 // These tokens can start an expression after `!`, but
3023 // can't continue an expression after an ident
3024 token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw),
3025 token::Literal(..) | token::Pound => true,
3026 token::Interpolated(ref nt) => match nt.0 {
3027 token::NtIdent(..) | token::NtExpr(..) |
3028 token::NtBlock(..) | token::NtPath(..) => true,
3033 let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
3034 if cannot_continue_expr {
3036 // Emit the error ...
3037 let mut err = self.diagnostic()
3038 .struct_span_err(self.span,
3039 &format!("unexpected {} after identifier",
3040 self.this_token_descr()));
3041 // span the `not` plus trailing whitespace to avoid
3042 // trailing whitespace after the `!` in our suggestion
3043 let to_replace = self.sess.source_map()
3044 .span_until_non_whitespace(lo.to(self.span));
3045 err.span_suggestion_short_with_applicability(
3047 "use `!` to perform logical negation",
3049 Applicability::MachineApplicable
3052 // —and recover! (just as if we were in the block
3053 // for the `token::Not` arm)
3054 let e = self.parse_prefix_expr(None);
3055 let (span, e) = self.interpolated_or_expr_span(e)?;
3056 (lo.to(span), self.mk_unary(UnOp::Not, e))
3058 return self.parse_dot_or_call_expr(Some(attrs));
3061 _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
3063 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
3066 /// Parse an associative expression
3068 /// This parses an expression accounting for associativity and precedence of the operators in
3071 fn parse_assoc_expr(&mut self,
3072 already_parsed_attrs: Option<ThinVec<Attribute>>)
3073 -> PResult<'a, P<Expr>> {
3074 self.parse_assoc_expr_with(0, already_parsed_attrs.into())
3077 /// Parse an associative expression with operators of at least `min_prec` precedence
3078 fn parse_assoc_expr_with(&mut self,
3081 -> PResult<'a, P<Expr>> {
3082 let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
3085 let attrs = match lhs {
3086 LhsExpr::AttributesParsed(attrs) => Some(attrs),
3089 if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token) {
3090 return self.parse_prefix_range_expr(attrs);
3092 self.parse_prefix_expr(attrs)?
3096 if self.expr_is_complete(&lhs) {
3097 // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
3100 self.expected_tokens.push(TokenType::Operator);
3101 while let Some(op) = AssocOp::from_token(&self.token) {
3103 // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
3104 // it refers to. Interpolated identifiers are unwrapped early and never show up here
3105 // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
3106 // it as "interpolated", it doesn't change the answer for non-interpolated idents.
3107 let lhs_span = match (self.prev_token_kind, &lhs.node) {
3108 (PrevTokenKind::Interpolated, _) => self.prev_span,
3109 (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
3110 if path.segments.len() == 1 => self.prev_span,
3114 let cur_op_span = self.span;
3115 let restrictions = if op.is_assign_like() {
3116 self.restrictions & Restrictions::NO_STRUCT_LITERAL
3120 if op.precedence() < min_prec {
3123 // Check for deprecated `...` syntax
3124 if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
3125 self.err_dotdotdot_syntax(self.span);
3129 if op.is_comparison() {
3130 self.check_no_chained_comparison(&lhs, &op);
3133 if op == AssocOp::As {
3134 lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
3136 } else if op == AssocOp::Colon {
3137 lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) {
3140 err.span_label(self.span,
3141 "expecting a type here because of type ascription");
3142 let cm = self.sess.source_map();
3143 let cur_pos = cm.lookup_char_pos(self.span.lo());
3144 let op_pos = cm.lookup_char_pos(cur_op_span.hi());
3145 if cur_pos.line != op_pos.line {
3146 err.span_suggestion_with_applicability(
3148 "try using a semicolon",
3150 Applicability::MaybeIncorrect // speculative
3157 } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
3158 // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
3159 // generalise it to the Fixity::None code.
3161 // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
3162 // two variants are handled with `parse_prefix_range_expr` call above.
3163 let rhs = if self.is_at_start_of_range_notation_rhs() {
3164 Some(self.parse_assoc_expr_with(op.precedence() + 1,
3165 LhsExpr::NotYetParsed)?)
3169 let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
3174 let limits = if op == AssocOp::DotDot {
3175 RangeLimits::HalfOpen
3180 let r = self.mk_range(Some(lhs), rhs, limits)?;
3181 lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
3185 let rhs = match op.fixity() {
3186 Fixity::Right => self.with_res(
3187 restrictions - Restrictions::STMT_EXPR,
3189 this.parse_assoc_expr_with(op.precedence(),
3190 LhsExpr::NotYetParsed)
3192 Fixity::Left => self.with_res(
3193 restrictions - Restrictions::STMT_EXPR,
3195 this.parse_assoc_expr_with(op.precedence() + 1,
3196 LhsExpr::NotYetParsed)
3198 // We currently have no non-associative operators that are not handled above by
3199 // the special cases. The code is here only for future convenience.
3200 Fixity::None => self.with_res(
3201 restrictions - Restrictions::STMT_EXPR,
3203 this.parse_assoc_expr_with(op.precedence() + 1,
3204 LhsExpr::NotYetParsed)
3208 let span = lhs_span.to(rhs.span);
3210 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
3211 AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
3212 AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
3213 AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
3214 AssocOp::Greater | AssocOp::GreaterEqual => {
3215 let ast_op = op.to_ast_binop().unwrap();
3216 let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
3217 self.mk_expr(span, binary, ThinVec::new())
3220 self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
3221 AssocOp::ObsoleteInPlace =>
3222 self.mk_expr(span, ExprKind::ObsoleteInPlace(lhs, rhs), ThinVec::new()),
3223 AssocOp::AssignOp(k) => {
3225 token::Plus => BinOpKind::Add,
3226 token::Minus => BinOpKind::Sub,
3227 token::Star => BinOpKind::Mul,
3228 token::Slash => BinOpKind::Div,
3229 token::Percent => BinOpKind::Rem,
3230 token::Caret => BinOpKind::BitXor,
3231 token::And => BinOpKind::BitAnd,
3232 token::Or => BinOpKind::BitOr,
3233 token::Shl => BinOpKind::Shl,
3234 token::Shr => BinOpKind::Shr,
3236 let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
3237 self.mk_expr(span, aopexpr, ThinVec::new())
3239 AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
3240 self.bug("AssocOp should have been handled by special case")
3244 if op.fixity() == Fixity::None { break }
3249 fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
3250 expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
3251 -> PResult<'a, P<Expr>> {
3252 let mk_expr = |this: &mut Self, rhs: P<Ty>| {
3253 this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
3256 // Save the state of the parser before parsing type normally, in case there is a
3257 // LessThan comparison after this cast.
3258 let parser_snapshot_before_type = self.clone();
3259 match self.parse_ty_no_plus() {
3261 Ok(mk_expr(self, rhs))
3263 Err(mut type_err) => {
3264 // Rewind to before attempting to parse the type with generics, to recover
3265 // from situations like `x as usize < y` in which we first tried to parse
3266 // `usize < y` as a type with generic arguments.
3267 let parser_snapshot_after_type = self.clone();
3268 mem::replace(self, parser_snapshot_before_type);
3270 match self.parse_path(PathStyle::Expr) {
3272 let (op_noun, op_verb) = match self.token {
3273 token::Lt => ("comparison", "comparing"),
3274 token::BinOp(token::Shl) => ("shift", "shifting"),
3276 // We can end up here even without `<` being the next token, for
3277 // example because `parse_ty_no_plus` returns `Err` on keywords,
3278 // but `parse_path` returns `Ok` on them due to error recovery.
3279 // Return original error and parser state.
3280 mem::replace(self, parser_snapshot_after_type);
3281 return Err(type_err);
3285 // Successfully parsed the type path leaving a `<` yet to parse.
3288 // Report non-fatal diagnostics, keep `x as usize` as an expression
3289 // in AST and continue parsing.
3290 let msg = format!("`<` is interpreted as a start of generic \
3291 arguments for `{}`, not a {}", path, op_noun);
3292 let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
3293 err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span),
3294 "interpreted as generic arguments");
3295 err.span_label(self.span, format!("not interpreted as {}", op_noun));
3297 let expr = mk_expr(self, P(Ty {
3299 node: TyKind::Path(None, path),
3300 id: ast::DUMMY_NODE_ID
3303 let expr_str = self.sess.source_map().span_to_snippet(expr.span)
3304 .unwrap_or_else(|_| pprust::expr_to_string(&expr));
3305 err.span_suggestion_with_applicability(
3307 &format!("try {} the cast value", op_verb),
3308 format!("({})", expr_str),
3309 Applicability::MachineApplicable
3315 Err(mut path_err) => {
3316 // Couldn't parse as a path, return original error and parser state.
3318 mem::replace(self, parser_snapshot_after_type);
3326 /// Produce an error if comparison operators are chained (RFC #558).
3327 /// We only need to check lhs, not rhs, because all comparison ops
3328 /// have same precedence and are left-associative
3329 fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
3330 debug_assert!(outer_op.is_comparison(),
3331 "check_no_chained_comparison: {:?} is not comparison",
3334 ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
3335 // respan to include both operators
3336 let op_span = op.span.to(self.span);
3337 let mut err = self.diagnostic().struct_span_err(op_span,
3338 "chained comparison operators require parentheses");
3339 if op.node == BinOpKind::Lt &&
3340 *outer_op == AssocOp::Less || // Include `<` to provide this recommendation
3341 *outer_op == AssocOp::Greater // even in a case like the following:
3342 { // Foo<Bar<Baz<Qux, ()>>>
3344 "use `::<...>` instead of `<...>` if you meant to specify type arguments");
3345 err.help("or use `(...)` if you meant to specify fn arguments");
3353 /// Parse prefix-forms of range notation: `..expr`, `..`, `..=expr`
3354 fn parse_prefix_range_expr(&mut self,
3355 already_parsed_attrs: Option<ThinVec<Attribute>>)
3356 -> PResult<'a, P<Expr>> {
3357 // Check for deprecated `...` syntax
3358 if self.token == token::DotDotDot {
3359 self.err_dotdotdot_syntax(self.span);
3362 debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token),
3363 "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
3365 let tok = self.token.clone();
3366 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
3368 let mut hi = self.span;
3370 let opt_end = if self.is_at_start_of_range_notation_rhs() {
3371 // RHS must be parsed with more associativity than the dots.
3372 let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
3373 Some(self.parse_assoc_expr_with(next_prec,
3374 LhsExpr::NotYetParsed)
3382 let limits = if tok == token::DotDot {
3383 RangeLimits::HalfOpen
3388 let r = self.mk_range(None, opt_end, limits)?;
3389 Ok(self.mk_expr(lo.to(hi), r, attrs))
3392 fn is_at_start_of_range_notation_rhs(&self) -> bool {
3393 if self.token.can_begin_expr() {
3394 // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
3395 if self.token == token::OpenDelim(token::Brace) {
3396 return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
3404 /// Parse an 'if' or 'if let' expression ('if' token already eaten)
3405 fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3406 if self.check_keyword(keywords::Let) {
3407 return self.parse_if_let_expr(attrs);
3409 let lo = self.prev_span;
3410 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3412 // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
3413 // verify that the last statement is either an implicit return (no `;`) or an explicit
3414 // return. This won't catch blocks with an explicit `return`, but that would be caught by
3415 // the dead code lint.
3416 if self.eat_keyword(keywords::Else) || !cond.returns() {
3417 let sp = self.sess.source_map().next_point(lo);
3418 let mut err = self.diagnostic()
3419 .struct_span_err(sp, "missing condition for `if` statemement");
3420 err.span_label(sp, "expected if condition here");
3423 let not_block = self.token != token::OpenDelim(token::Brace);
3424 let thn = self.parse_block().map_err(|mut err| {
3426 err.span_label(lo, "this `if` statement has a condition, but no block");
3430 let mut els: Option<P<Expr>> = None;
3431 let mut hi = thn.span;
3432 if self.eat_keyword(keywords::Else) {
3433 let elexpr = self.parse_else_expr()?;
3437 Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
3440 /// Parse an 'if let' expression ('if' token already eaten)
3441 fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
3442 -> PResult<'a, P<Expr>> {
3443 let lo = self.prev_span;
3444 self.expect_keyword(keywords::Let)?;
3445 let pats = self.parse_pats()?;
3446 self.expect(&token::Eq)?;
3447 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3448 let thn = self.parse_block()?;
3449 let (hi, els) = if self.eat_keyword(keywords::Else) {
3450 let expr = self.parse_else_expr()?;
3451 (expr.span, Some(expr))
3455 Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
3458 // `move |args| expr`
3459 fn parse_lambda_expr(&mut self,
3460 attrs: ThinVec<Attribute>)
3461 -> PResult<'a, P<Expr>>
3464 let movability = if self.eat_keyword(keywords::Static) {
3469 let asyncness = if self.span.rust_2018() {
3470 self.parse_asyncness()
3474 let capture_clause = if self.eat_keyword(keywords::Move) {
3479 let decl = self.parse_fn_block_decl()?;
3480 let decl_hi = self.prev_span;
3481 let body = match decl.output {
3482 FunctionRetTy::Default(_) => {
3483 let restrictions = self.restrictions - Restrictions::STMT_EXPR;
3484 self.parse_expr_res(restrictions, None)?
3487 // If an explicit return type is given, require a
3488 // block to appear (RFC 968).
3489 let body_lo = self.span;
3490 self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
3496 ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
3500 // `else` token already eaten
3501 fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
3502 if self.eat_keyword(keywords::If) {
3503 return self.parse_if_expr(ThinVec::new());
3505 let blk = self.parse_block()?;
3506 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
3510 /// Parse a 'for' .. 'in' expression ('for' token already eaten)
3511 fn parse_for_expr(&mut self, opt_label: Option<Label>,
3513 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3514 // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
3516 let pat = self.parse_top_level_pat()?;
3517 if !self.eat_keyword(keywords::In) {
3518 let in_span = self.prev_span.between(self.span);
3519 let mut err = self.sess.span_diagnostic
3520 .struct_span_err(in_span, "missing `in` in `for` loop");
3521 err.span_suggestion_short_with_applicability(
3522 in_span, "try adding `in` here", " in ".into(),
3523 // has been misleading, at least in the past (closed Issue #48492)
3524 Applicability::MaybeIncorrect
3528 let in_span = self.prev_span;
3529 if self.eat_keyword(keywords::In) {
3530 // a common typo: `for _ in in bar {}`
3531 let mut err = self.sess.span_diagnostic.struct_span_err(
3533 "expected iterable, found keyword `in`",
3535 err.span_suggestion_short_with_applicability(
3536 in_span.until(self.prev_span),
3537 "remove the duplicated `in`",
3539 Applicability::MachineApplicable,
3541 err.note("if you meant to use emplacement syntax, it is obsolete (for now, anyway)");
3542 err.note("for more information on the status of emplacement syntax, see <\
3543 https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>");
3546 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3547 let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
3548 attrs.extend(iattrs);
3550 let hi = self.prev_span;
3551 Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
3554 /// Parse a 'while' or 'while let' expression ('while' token already eaten)
3555 fn parse_while_expr(&mut self, opt_label: Option<Label>,
3557 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3558 if self.token.is_keyword(keywords::Let) {
3559 return self.parse_while_let_expr(opt_label, span_lo, attrs);
3561 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3562 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3563 attrs.extend(iattrs);
3564 let span = span_lo.to(body.span);
3565 return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs));
3568 /// Parse a 'while let' expression ('while' token already eaten)
3569 fn parse_while_let_expr(&mut self, opt_label: Option<Label>,
3571 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3572 self.expect_keyword(keywords::Let)?;
3573 let pats = self.parse_pats()?;
3574 self.expect(&token::Eq)?;
3575 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3576 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3577 attrs.extend(iattrs);
3578 let span = span_lo.to(body.span);
3579 return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
3582 // parse `loop {...}`, `loop` token already eaten
3583 fn parse_loop_expr(&mut self, opt_label: Option<Label>,
3585 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3586 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3587 attrs.extend(iattrs);
3588 let span = span_lo.to(body.span);
3589 Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
3592 /// Parse an `async move {...}` expression
3593 pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>)
3594 -> PResult<'a, P<Expr>>
3596 let span_lo = self.span;
3597 self.expect_keyword(keywords::Async)?;
3598 let capture_clause = if self.eat_keyword(keywords::Move) {
3603 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3604 attrs.extend(iattrs);
3606 span_lo.to(body.span),
3607 ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs))
3610 /// Parse a `try {...}` expression (`try` token already eaten)
3611 fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
3612 -> PResult<'a, P<Expr>>
3614 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3615 attrs.extend(iattrs);
3616 Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
3619 // `match` token already eaten
3620 fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3621 let match_span = self.prev_span;
3622 let lo = self.prev_span;
3623 let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL,
3625 if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
3626 if self.token == token::Token::Semi {
3627 e.span_suggestion_short_with_applicability(
3629 "try removing this `match`",
3631 Applicability::MaybeIncorrect // speculative
3636 attrs.extend(self.parse_inner_attributes()?);
3638 let mut arms: Vec<Arm> = Vec::new();
3639 while self.token != token::CloseDelim(token::Brace) {
3640 match self.parse_arm() {
3641 Ok(arm) => arms.push(arm),
3643 // Recover by skipping to the end of the block.
3645 self.recover_stmt();
3646 let span = lo.to(self.span);
3647 if self.token == token::CloseDelim(token::Brace) {
3650 return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
3656 return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
3659 crate fn parse_arm(&mut self) -> PResult<'a, Arm> {
3660 maybe_whole!(self, NtArm, |x| x);
3662 let attrs = self.parse_outer_attributes()?;
3663 // Allow a '|' before the pats (RFC 1925)
3664 self.eat(&token::BinOp(token::Or));
3665 let pats = self.parse_pats()?;
3666 let guard = if self.eat_keyword(keywords::If) {
3667 Some(Guard::If(self.parse_expr()?))
3671 let arrow_span = self.span;
3672 self.expect(&token::FatArrow)?;
3673 let arm_start_span = self.span;
3675 let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
3676 .map_err(|mut err| {
3677 err.span_label(arrow_span, "while parsing the `match` arm starting here");
3681 let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
3682 && self.token != token::CloseDelim(token::Brace);
3685 let cm = self.sess.source_map();
3686 self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
3687 .map_err(|mut err| {
3688 match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
3689 (Ok(ref expr_lines), Ok(ref arm_start_lines))
3690 if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
3691 && expr_lines.lines.len() == 2
3692 && self.token == token::FatArrow => {
3693 // We check whether there's any trailing code in the parse span,
3694 // if there isn't, we very likely have the following:
3697 // | -- - missing comma
3703 // | parsed until here as `"y" & X`
3704 err.span_suggestion_short_with_applicability(
3705 cm.next_point(arm_start_span),
3706 "missing a comma here to end this `match` arm",
3708 Applicability::MachineApplicable
3712 err.span_label(arrow_span,
3713 "while parsing the `match` arm starting here");
3719 self.eat(&token::Comma);
3730 /// Parse an expression
3732 pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
3733 self.parse_expr_res(Restrictions::empty(), None)
3736 /// Evaluate the closure with restrictions in place.
3738 /// After the closure is evaluated, restrictions are reset.
3739 fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T
3740 where F: FnOnce(&mut Self) -> T
3742 let old = self.restrictions;
3743 self.restrictions = r;
3745 self.restrictions = old;
3750 /// Parse an expression, subject to the given restrictions
3752 fn parse_expr_res(&mut self, r: Restrictions,
3753 already_parsed_attrs: Option<ThinVec<Attribute>>)
3754 -> PResult<'a, P<Expr>> {
3755 self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
3758 /// Parse the RHS of a local variable declaration (e.g., '= 14;')
3759 fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
3760 if self.eat(&token::Eq) {
3761 Ok(Some(self.parse_expr()?))
3763 Ok(Some(self.parse_expr()?))
3769 /// Parse patterns, separated by '|' s
3770 fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3771 let mut pats = Vec::new();
3773 pats.push(self.parse_top_level_pat()?);
3775 if self.token == token::OrOr {
3776 let mut err = self.struct_span_err(self.span,
3777 "unexpected token `||` after pattern");
3778 err.span_suggestion_with_applicability(
3780 "use a single `|` to specify multiple patterns",
3782 Applicability::MachineApplicable
3786 } else if self.eat(&token::BinOp(token::Or)) {
3794 // Parses a parenthesized list of patterns like
3795 // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns:
3796 // - a vector of the patterns that were parsed
3797 // - an option indicating the index of the `..` element
3798 // - a boolean indicating whether a trailing comma was present.
3799 // Trailing commas are significant because (p) and (p,) are different patterns.
3800 fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3801 self.expect(&token::OpenDelim(token::Paren))?;
3802 let result = self.parse_pat_list()?;
3803 self.expect(&token::CloseDelim(token::Paren))?;
3807 fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3808 let mut fields = Vec::new();
3809 let mut ddpos = None;
3810 let mut trailing_comma = false;
3812 if self.eat(&token::DotDot) {
3813 if ddpos.is_none() {
3814 ddpos = Some(fields.len());
3816 // Emit a friendly error, ignore `..` and continue parsing
3817 self.struct_span_err(
3819 "`..` can only be used once per tuple or tuple struct pattern",
3821 .span_label(self.prev_span, "can only be used once per pattern")
3824 } else if !self.check(&token::CloseDelim(token::Paren)) {
3825 fields.push(self.parse_pat(None)?);
3830 trailing_comma = self.eat(&token::Comma);
3831 if !trailing_comma {
3836 if ddpos == Some(fields.len()) && trailing_comma {
3837 // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
3838 let msg = "trailing comma is not permitted after `..`";
3839 self.struct_span_err(self.prev_span, msg)
3840 .span_label(self.prev_span, msg)
3844 Ok((fields, ddpos, trailing_comma))
3847 fn parse_pat_vec_elements(
3849 ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3850 let mut before = Vec::new();
3851 let mut slice = None;
3852 let mut after = Vec::new();
3853 let mut first = true;
3854 let mut before_slice = true;
3856 while self.token != token::CloseDelim(token::Bracket) {
3860 self.expect(&token::Comma)?;
3862 if self.token == token::CloseDelim(token::Bracket)
3863 && (before_slice || !after.is_empty()) {
3869 if self.eat(&token::DotDot) {
3871 if self.check(&token::Comma) ||
3872 self.check(&token::CloseDelim(token::Bracket)) {
3873 slice = Some(P(Pat {
3874 id: ast::DUMMY_NODE_ID,
3875 node: PatKind::Wild,
3876 span: self.prev_span,
3878 before_slice = false;
3884 let subpat = self.parse_pat(None)?;
3885 if before_slice && self.eat(&token::DotDot) {
3886 slice = Some(subpat);
3887 before_slice = false;
3888 } else if before_slice {
3889 before.push(subpat);
3895 Ok((before, slice, after))
3901 attrs: Vec<Attribute>
3902 ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> {
3903 // Check if a colon exists one ahead. This means we're parsing a fieldname.
3905 let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3906 // Parsing a pattern of the form "fieldname: pat"
3907 let fieldname = self.parse_field_name()?;
3909 let pat = self.parse_pat(None)?;
3911 (pat, fieldname, false)
3913 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3914 let is_box = self.eat_keyword(keywords::Box);
3915 let boxed_span = self.span;
3916 let is_ref = self.eat_keyword(keywords::Ref);
3917 let is_mut = self.eat_keyword(keywords::Mut);
3918 let fieldname = self.parse_ident()?;
3919 hi = self.prev_span;
3921 let bind_type = match (is_ref, is_mut) {
3922 (true, true) => BindingMode::ByRef(Mutability::Mutable),
3923 (true, false) => BindingMode::ByRef(Mutability::Immutable),
3924 (false, true) => BindingMode::ByValue(Mutability::Mutable),
3925 (false, false) => BindingMode::ByValue(Mutability::Immutable),
3927 let fieldpat = P(Pat {
3928 id: ast::DUMMY_NODE_ID,
3929 node: PatKind::Ident(bind_type, fieldname, None),
3930 span: boxed_span.to(hi),
3933 let subpat = if is_box {
3935 id: ast::DUMMY_NODE_ID,
3936 node: PatKind::Box(fieldpat),
3942 (subpat, fieldname, true)
3945 Ok(source_map::Spanned {
3947 node: ast::FieldPat {
3951 attrs: attrs.into(),
3956 /// Parse the fields of a struct-like pattern
3957 fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> {
3958 let mut fields = Vec::new();
3959 let mut etc = false;
3960 let mut ate_comma = true;
3961 let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
3962 let mut etc_span = None;
3964 while self.token != token::CloseDelim(token::Brace) {
3965 let attrs = self.parse_outer_attributes()?;
3968 // check that a comma comes after every field
3970 let err = self.struct_span_err(self.prev_span, "expected `,`");
3971 if let Some(mut delayed) = delayed_err {
3978 if self.check(&token::DotDot) || self.token == token::DotDotDot {
3980 let mut etc_sp = self.span;
3982 if self.token == token::DotDotDot { // Issue #46718
3983 // Accept `...` as if it were `..` to avoid further errors
3984 let mut err = self.struct_span_err(self.span,
3985 "expected field pattern, found `...`");
3986 err.span_suggestion_with_applicability(
3988 "to omit remaining fields, use one fewer `.`",
3990 Applicability::MachineApplicable
3994 self.bump(); // `..` || `...`
3996 if self.token == token::CloseDelim(token::Brace) {
3997 etc_span = Some(etc_sp);
4000 let token_str = self.this_token_descr();
4001 let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
4003 err.span_label(self.span, "expected `}`");
4004 let mut comma_sp = None;
4005 if self.token == token::Comma { // Issue #49257
4006 etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span));
4007 err.span_label(etc_sp,
4008 "`..` must be at the end and cannot have a trailing comma");
4009 comma_sp = Some(self.span);
4014 etc_span = Some(etc_sp.until(self.span));
4015 if self.token == token::CloseDelim(token::Brace) {
4016 // If the struct looks otherwise well formed, recover and continue.
4017 if let Some(sp) = comma_sp {
4018 err.span_suggestion_short_with_applicability(
4020 "remove this comma",
4022 Applicability::MachineApplicable,
4027 } else if self.token.is_ident() && ate_comma {
4028 // Accept fields coming after `..,`.
4029 // This way we avoid "pattern missing fields" errors afterwards.
4030 // We delay this error until the end in order to have a span for a
4032 if let Some(mut delayed_err) = delayed_err {
4036 delayed_err = Some(err);
4039 if let Some(mut err) = delayed_err {
4046 fields.push(match self.parse_pat_field(lo, attrs) {
4049 if let Some(mut delayed_err) = delayed_err {
4055 ate_comma = self.eat(&token::Comma);
4058 if let Some(mut err) = delayed_err {
4059 if let Some(etc_span) = etc_span {
4060 err.multipart_suggestion(
4061 "move the `..` to the end of the field list",
4063 (etc_span, String::new()),
4064 (self.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
4070 return Ok((fields, etc));
4073 fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
4074 if self.token.is_path_start() {
4076 let (qself, path) = if self.eat_lt() {
4077 // Parse a qualified path
4078 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4081 // Parse an unqualified path
4082 (None, self.parse_path(PathStyle::Expr)?)
4084 let hi = self.prev_span;
4085 Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
4087 self.parse_literal_maybe_minus()
4091 // helper function to decide whether to parse as ident binding or to try to do
4092 // something more complex like range patterns
4093 fn parse_as_ident(&mut self) -> bool {
4094 self.look_ahead(1, |t| match *t {
4095 token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
4096 token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false),
4097 // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the
4098 // range pattern branch
4099 token::DotDot => None,
4101 }).unwrap_or_else(|| self.look_ahead(2, |t| match *t {
4102 token::Comma | token::CloseDelim(token::Bracket) => true,
4107 /// A wrapper around `parse_pat` with some special error handling for the
4108 /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
4109 /// to subpatterns within such).
4110 fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
4111 let pat = self.parse_pat(None)?;
4112 if self.token == token::Comma {
4113 // An unexpected comma after a top-level pattern is a clue that the
4114 // user (perhaps more accustomed to some other language) forgot the
4115 // parentheses in what should have been a tuple pattern; return a
4116 // suggestion-enhanced error here rather than choking on the comma
4118 let comma_span = self.span;
4120 if let Err(mut err) = self.parse_pat_list() {
4121 // We didn't expect this to work anyway; we just wanted
4122 // to advance to the end of the comma-sequence so we know
4123 // the span to suggest parenthesizing
4126 let seq_span = pat.span.to(self.prev_span);
4127 let mut err = self.struct_span_err(comma_span,
4128 "unexpected `,` in pattern");
4129 if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) {
4130 err.span_suggestion_with_applicability(
4132 "try adding parentheses",
4133 format!("({})", seq_snippet),
4134 Applicability::MachineApplicable
4142 /// Parse a pattern.
4143 pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
4144 self.parse_pat_with_range_pat(true, expected)
4147 /// Parse a pattern, with a setting whether modern range patterns e.g., `a..=b`, `a..b` are
4149 fn parse_pat_with_range_pat(
4151 allow_range_pat: bool,
4152 expected: Option<&'static str>,
4153 ) -> PResult<'a, P<Pat>> {
4154 maybe_whole!(self, NtPat, |x| x);
4159 token::BinOp(token::And) | token::AndAnd => {
4160 // Parse &pat / &mut pat
4162 let mutbl = self.parse_mutability();
4163 if let token::Lifetime(ident) = self.token {
4164 let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern",
4166 err.span_label(self.span, "unexpected lifetime");
4169 let subpat = self.parse_pat_with_range_pat(false, expected)?;
4170 pat = PatKind::Ref(subpat, mutbl);
4172 token::OpenDelim(token::Paren) => {
4173 // Parse (pat,pat,pat,...) as tuple pattern
4174 let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?;
4175 pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma {
4176 PatKind::Paren(fields.into_iter().nth(0).unwrap())
4178 PatKind::Tuple(fields, ddpos)
4181 token::OpenDelim(token::Bracket) => {
4182 // Parse [pat,pat,...] as slice pattern
4184 let (before, slice, after) = self.parse_pat_vec_elements()?;
4185 self.expect(&token::CloseDelim(token::Bracket))?;
4186 pat = PatKind::Slice(before, slice, after);
4188 // At this point, token != &, &&, (, [
4189 _ => if self.eat_keyword(keywords::Underscore) {
4191 pat = PatKind::Wild;
4192 } else if self.eat_keyword(keywords::Mut) {
4193 // Parse mut ident @ pat / mut ref ident @ pat
4194 let mutref_span = self.prev_span.to(self.span);
4195 let binding_mode = if self.eat_keyword(keywords::Ref) {
4197 .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
4198 .span_suggestion_with_applicability(
4200 "try switching the order",
4202 Applicability::MachineApplicable
4204 BindingMode::ByRef(Mutability::Mutable)
4206 BindingMode::ByValue(Mutability::Mutable)
4208 pat = self.parse_pat_ident(binding_mode)?;
4209 } else if self.eat_keyword(keywords::Ref) {
4210 // Parse ref ident @ pat / ref mut ident @ pat
4211 let mutbl = self.parse_mutability();
4212 pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
4213 } else if self.eat_keyword(keywords::Box) {
4215 let subpat = self.parse_pat_with_range_pat(false, None)?;
4216 pat = PatKind::Box(subpat);
4217 } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
4218 self.parse_as_ident() {
4219 // Parse ident @ pat
4220 // This can give false positives and parse nullary enums,
4221 // they are dealt with later in resolve
4222 let binding_mode = BindingMode::ByValue(Mutability::Immutable);
4223 pat = self.parse_pat_ident(binding_mode)?;
4224 } else if self.token.is_path_start() {
4225 // Parse pattern starting with a path
4226 let (qself, path) = if self.eat_lt() {
4227 // Parse a qualified path
4228 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4231 // Parse an unqualified path
4232 (None, self.parse_path(PathStyle::Expr)?)
4235 token::Not if qself.is_none() => {
4236 // Parse macro invocation
4238 let (delim, tts) = self.expect_delimited_token_tree()?;
4239 let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim });
4240 pat = PatKind::Mac(mac);
4242 token::DotDotDot | token::DotDotEq | token::DotDot => {
4243 let end_kind = match self.token {
4244 token::DotDot => RangeEnd::Excluded,
4245 token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot),
4246 token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq),
4247 _ => panic!("can only parse `..`/`...`/`..=` for ranges \
4250 let op_span = self.span;
4252 let span = lo.to(self.prev_span);
4253 let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
4255 let end = self.parse_pat_range_end()?;
4256 let op = Spanned { span: op_span, node: end_kind };
4257 pat = PatKind::Range(begin, end, op);
4259 token::OpenDelim(token::Brace) => {
4260 if qself.is_some() {
4261 let msg = "unexpected `{` after qualified path";
4262 let mut err = self.fatal(msg);
4263 err.span_label(self.span, msg);
4266 // Parse struct pattern
4268 let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
4270 self.recover_stmt();
4274 pat = PatKind::Struct(path, fields, etc);
4276 token::OpenDelim(token::Paren) => {
4277 if qself.is_some() {
4278 let msg = "unexpected `(` after qualified path";
4279 let mut err = self.fatal(msg);
4280 err.span_label(self.span, msg);
4283 // Parse tuple struct or enum pattern
4284 let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?;
4285 pat = PatKind::TupleStruct(path, fields, ddpos)
4287 _ => pat = PatKind::Path(qself, path),
4290 // Try to parse everything else as literal with optional minus
4291 match self.parse_literal_maybe_minus() {
4293 let op_span = self.span;
4294 if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
4295 self.check(&token::DotDotDot) {
4296 let end_kind = if self.eat(&token::DotDotDot) {
4297 RangeEnd::Included(RangeSyntax::DotDotDot)
4298 } else if self.eat(&token::DotDotEq) {
4299 RangeEnd::Included(RangeSyntax::DotDotEq)
4300 } else if self.eat(&token::DotDot) {
4303 panic!("impossible case: we already matched \
4304 on a range-operator token")
4306 let end = self.parse_pat_range_end()?;
4307 let op = Spanned { span: op_span, node: end_kind };
4308 pat = PatKind::Range(begin, end, op);
4310 pat = PatKind::Lit(begin);
4314 self.cancel(&mut err);
4315 let expected = expected.unwrap_or("pattern");
4317 "expected {}, found {}",
4319 self.this_token_descr(),
4321 let mut err = self.fatal(&msg);
4322 err.span_label(self.span, format!("expected {}", expected));
4329 let pat = Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID };
4330 let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
4332 if !allow_range_pat {
4335 _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
4337 PatKind::Range(..) => {
4338 let mut err = self.struct_span_err(
4340 "the range pattern here has ambiguous interpretation",
4342 err.span_suggestion_with_applicability(
4344 "add parentheses to clarify the precedence",
4345 format!("({})", pprust::pat_to_string(&pat)),
4346 // "ambiguous interpretation" implies that we have to be guessing
4347 Applicability::MaybeIncorrect
4358 /// Parse ident or ident @ pat
4359 /// used by the copy foo and ref foo patterns to give a good
4360 /// error message when parsing mistakes like ref foo(a,b)
4361 fn parse_pat_ident(&mut self,
4362 binding_mode: ast::BindingMode)
4363 -> PResult<'a, PatKind> {
4364 let ident = self.parse_ident()?;
4365 let sub = if self.eat(&token::At) {
4366 Some(self.parse_pat(Some("binding pattern"))?)
4371 // just to be friendly, if they write something like
4373 // we end up here with ( as the current token. This shortly
4374 // leads to a parse error. Note that if there is no explicit
4375 // binding mode then we do not end up here, because the lookahead
4376 // will direct us over to parse_enum_variant()
4377 if self.token == token::OpenDelim(token::Paren) {
4378 return Err(self.span_fatal(
4380 "expected identifier, found enum pattern"))
4383 Ok(PatKind::Ident(binding_mode, ident, sub))
4386 /// Parse a local variable declaration
4387 fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
4388 let lo = self.prev_span;
4389 let pat = self.parse_top_level_pat()?;
4391 let (err, ty) = if self.eat(&token::Colon) {
4392 // Save the state of the parser before parsing type normally, in case there is a `:`
4393 // instead of an `=` typo.
4394 let parser_snapshot_before_type = self.clone();
4395 let colon_sp = self.prev_span;
4396 match self.parse_ty() {
4397 Ok(ty) => (None, Some(ty)),
4399 // Rewind to before attempting to parse the type and continue parsing
4400 let parser_snapshot_after_type = self.clone();
4401 mem::replace(self, parser_snapshot_before_type);
4403 let snippet = self.sess.source_map().span_to_snippet(pat.span).unwrap();
4404 err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
4405 (Some((parser_snapshot_after_type, colon_sp, err)), None)
4411 let init = match (self.parse_initializer(err.is_some()), err) {
4412 (Ok(init), None) => { // init parsed, ty parsed
4415 (Ok(init), Some((_, colon_sp, mut err))) => { // init parsed, ty error
4416 // Could parse the type as if it were the initializer, it is likely there was a
4417 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
4418 err.span_suggestion_short_with_applicability(
4420 "use `=` if you meant to assign",
4422 Applicability::MachineApplicable
4425 // As this was parsed successfully, continue as if the code has been fixed for the
4426 // rest of the file. It will still fail due to the emitted error, but we avoid
4430 (Err(mut init_err), Some((snapshot, _, ty_err))) => { // init error, ty error
4432 // Couldn't parse the type nor the initializer, only raise the type error and
4433 // return to the parser state before parsing the type as the initializer.
4434 // let x: <parse_error>;
4435 mem::replace(self, snapshot);
4438 (Err(err), None) => { // init error, ty parsed
4439 // Couldn't parse the initializer and we're not attempting to recover a failed
4440 // parse of the type, return the error.
4444 let hi = if self.token == token::Semi {
4453 id: ast::DUMMY_NODE_ID,
4459 /// Parse a structure field
4460 fn parse_name_and_ty(&mut self,
4463 attrs: Vec<Attribute>)
4464 -> PResult<'a, StructField> {
4465 let name = self.parse_ident()?;
4466 self.expect(&token::Colon)?;
4467 let ty = self.parse_ty()?;
4469 span: lo.to(self.prev_span),
4472 id: ast::DUMMY_NODE_ID,
4478 /// Emit an expected item after attributes error.
4479 fn expected_item_err(&self, attrs: &[Attribute]) {
4480 let message = match attrs.last() {
4481 Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
4482 _ => "expected item after attributes",
4485 self.span_err(self.prev_span, message);
4488 /// Parse a statement. This stops just before trailing semicolons on everything but items.
4489 /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
4490 pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
4491 Ok(self.parse_stmt_(true))
4494 // Eat tokens until we can be relatively sure we reached the end of the
4495 // statement. This is something of a best-effort heuristic.
4497 // We terminate when we find an unmatched `}` (without consuming it).
4498 fn recover_stmt(&mut self) {
4499 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
4502 // If `break_on_semi` is `Break`, then we will stop consuming tokens after
4503 // finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
4504 // approximate - it can mean we break too early due to macros, but that
4505 // should only lead to sub-optimal recovery, not inaccurate parsing).
4507 // If `break_on_block` is `Break`, then we will stop consuming tokens
4508 // after finding (and consuming) a brace-delimited block.
4509 fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) {
4510 let mut brace_depth = 0;
4511 let mut bracket_depth = 0;
4512 let mut in_block = false;
4513 debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
4514 break_on_semi, break_on_block);
4516 debug!("recover_stmt_ loop {:?}", self.token);
4518 token::OpenDelim(token::DelimToken::Brace) => {
4521 if break_on_block == BlockMode::Break &&
4523 bracket_depth == 0 {
4527 token::OpenDelim(token::DelimToken::Bracket) => {
4531 token::CloseDelim(token::DelimToken::Brace) => {
4532 if brace_depth == 0 {
4533 debug!("recover_stmt_ return - close delim {:?}", self.token);
4538 if in_block && bracket_depth == 0 && brace_depth == 0 {
4539 debug!("recover_stmt_ return - block end {:?}", self.token);
4543 token::CloseDelim(token::DelimToken::Bracket) => {
4545 if bracket_depth < 0 {
4551 debug!("recover_stmt_ return - Eof");
4556 if break_on_semi == SemiColonMode::Break &&
4558 bracket_depth == 0 {
4559 debug!("recover_stmt_ return - Semi");
4570 fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
4571 self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
4573 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4578 fn is_async_block(&mut self) -> bool {
4579 self.token.is_keyword(keywords::Async) &&
4582 self.look_ahead(1, |t| t.is_keyword(keywords::Move)) &&
4583 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
4585 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
4590 fn is_do_catch_block(&mut self) -> bool {
4591 self.token.is_keyword(keywords::Do) &&
4592 self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) &&
4593 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
4594 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4597 fn is_try_block(&mut self) -> bool {
4598 self.token.is_keyword(keywords::Try) &&
4599 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
4600 self.span.rust_2018() &&
4601 // prevent `while try {} {}`, `if try {} {} else {}`, etc.
4602 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4605 fn is_union_item(&self) -> bool {
4606 self.token.is_keyword(keywords::Union) &&
4607 self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
4610 fn is_crate_vis(&self) -> bool {
4611 self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
4614 fn is_extern_non_path(&self) -> bool {
4615 self.token.is_keyword(keywords::Extern) && self.look_ahead(1, |t| t != &token::ModSep)
4618 fn is_existential_type_decl(&self) -> bool {
4619 self.token.is_keyword(keywords::Existential) &&
4620 self.look_ahead(1, |t| t.is_keyword(keywords::Type))
4623 fn is_auto_trait_item(&mut self) -> bool {
4625 (self.token.is_keyword(keywords::Auto)
4626 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
4627 || // unsafe auto trait
4628 (self.token.is_keyword(keywords::Unsafe) &&
4629 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) &&
4630 self.look_ahead(2, |t| t.is_keyword(keywords::Trait)))
4633 fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span)
4634 -> PResult<'a, Option<P<Item>>> {
4635 let token_lo = self.span;
4636 let (ident, def) = match self.token {
4637 token::Ident(ident, false) if ident.name == keywords::Macro.name() => {
4639 let ident = self.parse_ident()?;
4640 let tokens = if self.check(&token::OpenDelim(token::Brace)) {
4641 match self.parse_token_tree() {
4642 TokenTree::Delimited(_, _, tts) => tts.stream(),
4643 _ => unreachable!(),
4645 } else if self.check(&token::OpenDelim(token::Paren)) {
4646 let args = self.parse_token_tree();
4647 let body = if self.check(&token::OpenDelim(token::Brace)) {
4648 self.parse_token_tree()
4653 TokenStream::new(vec![
4655 TokenTree::Token(token_lo.to(self.prev_span), token::FatArrow).into(),
4663 (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
4665 token::Ident(ident, _) if ident.name == "macro_rules" &&
4666 self.look_ahead(1, |t| *t == token::Not) => {
4667 let prev_span = self.prev_span;
4668 self.complain_if_pub_macro(&vis.node, prev_span);
4672 let ident = self.parse_ident()?;
4673 let (delim, tokens) = self.expect_delimited_token_tree()?;
4674 if delim != MacDelimiter::Brace {
4675 if !self.eat(&token::Semi) {
4676 let msg = "macros that expand to items must either \
4677 be surrounded with braces or followed by a semicolon";
4678 self.span_err(self.prev_span, msg);
4682 (ident, ast::MacroDef { tokens: tokens, legacy: true })
4684 _ => return Ok(None),
4687 let span = lo.to(self.prev_span);
4688 Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
4691 fn parse_stmt_without_recovery(&mut self,
4692 macro_legacy_warnings: bool)
4693 -> PResult<'a, Option<Stmt>> {
4694 maybe_whole!(self, NtStmt, |x| Some(x));
4696 let attrs = self.parse_outer_attributes()?;
4699 Ok(Some(if self.eat_keyword(keywords::Let) {
4701 id: ast::DUMMY_NODE_ID,
4702 node: StmtKind::Local(self.parse_local(attrs.into())?),
4703 span: lo.to(self.prev_span),
4705 } else if let Some(macro_def) = self.eat_macro_def(
4707 &source_map::respan(lo, VisibilityKind::Inherited),
4711 id: ast::DUMMY_NODE_ID,
4712 node: StmtKind::Item(macro_def),
4713 span: lo.to(self.prev_span),
4715 // Starts like a simple path, being careful to avoid contextual keywords
4716 // such as a union items, item with `crate` visibility or auto trait items.
4717 // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
4718 // like a path (1 token), but it fact not a path.
4719 // `union::b::c` - path, `union U { ... }` - not a path.
4720 // `crate::b::c` - path, `crate struct S;` - not a path.
4721 // `extern::b::c` - path, `extern crate c;` - not a path.
4722 } else if self.token.is_path_start() &&
4723 !self.token.is_qpath_start() &&
4724 !self.is_union_item() &&
4725 !self.is_crate_vis() &&
4726 !self.is_extern_non_path() &&
4727 !self.is_existential_type_decl() &&
4728 !self.is_auto_trait_item() {
4729 let pth = self.parse_path(PathStyle::Expr)?;
4731 if !self.eat(&token::Not) {
4732 let expr = if self.check(&token::OpenDelim(token::Brace)) {
4733 self.parse_struct_expr(lo, pth, ThinVec::new())?
4735 let hi = self.prev_span;
4736 self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), ThinVec::new())
4739 let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
4740 let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
4741 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
4744 return Ok(Some(Stmt {
4745 id: ast::DUMMY_NODE_ID,
4746 node: StmtKind::Expr(expr),
4747 span: lo.to(self.prev_span),
4751 // it's a macro invocation
4752 let id = match self.token {
4753 token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier
4754 _ => self.parse_ident()?,
4757 // check that we're pointing at delimiters (need to check
4758 // again after the `if`, because of `parse_ident`
4759 // consuming more tokens).
4761 token::OpenDelim(_) => {}
4763 // we only expect an ident if we didn't parse one
4765 let ident_str = if id.name == keywords::Invalid.name() {
4770 let tok_str = self.this_token_descr();
4771 let mut err = self.fatal(&format!("expected {}`(` or `{{`, found {}",
4774 err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str));
4779 let (delim, tts) = self.expect_delimited_token_tree()?;
4780 let hi = self.prev_span;
4782 let style = if delim == MacDelimiter::Brace {
4783 MacStmtStyle::Braces
4785 MacStmtStyle::NoBraces
4788 if id.name == keywords::Invalid.name() {
4789 let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim });
4790 let node = if delim == MacDelimiter::Brace ||
4791 self.token == token::Semi || self.token == token::Eof {
4792 StmtKind::Mac(P((mac, style, attrs.into())))
4794 // We used to incorrectly stop parsing macro-expanded statements here.
4795 // If the next token will be an error anyway but could have parsed with the
4796 // earlier behavior, stop parsing here and emit a warning to avoid breakage.
4797 else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token {
4798 // These can continue an expression, so we can't stop parsing and warn.
4799 token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
4800 token::BinOp(token::Minus) | token::BinOp(token::Star) |
4801 token::BinOp(token::And) | token::BinOp(token::Or) |
4802 token::AndAnd | token::OrOr |
4803 token::DotDot | token::DotDotDot | token::DotDotEq => false,
4806 self.warn_missing_semicolon();
4807 StmtKind::Mac(P((mac, style, attrs.into())))
4809 let e = self.mk_mac_expr(lo.to(hi), mac.node, ThinVec::new());
4810 let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
4811 let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
4815 id: ast::DUMMY_NODE_ID,
4820 // if it has a special ident, it's definitely an item
4822 // Require a semicolon or braces.
4823 if style != MacStmtStyle::Braces {
4824 if !self.eat(&token::Semi) {
4825 self.span_err(self.prev_span,
4826 "macros that expand to items must \
4827 either be surrounded with braces or \
4828 followed by a semicolon");
4831 let span = lo.to(hi);
4833 id: ast::DUMMY_NODE_ID,
4835 node: StmtKind::Item({
4837 span, id /*id is good here*/,
4838 ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })),
4839 respan(lo, VisibilityKind::Inherited),
4845 // FIXME: Bad copy of attrs
4846 let old_directory_ownership =
4847 mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
4848 let item = self.parse_item_(attrs.clone(), false, true)?;
4849 self.directory.ownership = old_directory_ownership;
4853 id: ast::DUMMY_NODE_ID,
4854 span: lo.to(i.span),
4855 node: StmtKind::Item(i),
4858 let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
4859 if !attrs.is_empty() {
4860 if s.prev_token_kind == PrevTokenKind::DocComment {
4861 s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
4862 } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
4863 s.span_err(s.span, "expected statement after outer attribute");
4868 // Do not attempt to parse an expression if we're done here.
4869 if self.token == token::Semi {
4870 unused_attrs(&attrs, self);
4875 if self.token == token::CloseDelim(token::Brace) {
4876 unused_attrs(&attrs, self);
4880 // Remainder are line-expr stmts.
4881 let e = self.parse_expr_res(
4882 Restrictions::STMT_EXPR, Some(attrs.into()))?;
4884 id: ast::DUMMY_NODE_ID,
4885 span: lo.to(e.span),
4886 node: StmtKind::Expr(e),
4893 /// Is this expression a successfully-parsed statement?
4894 fn expr_is_complete(&mut self, e: &Expr) -> bool {
4895 self.restrictions.contains(Restrictions::STMT_EXPR) &&
4896 !classify::expr_requires_semi_to_be_stmt(e)
4899 /// Parse a block. No inner attrs are allowed.
4900 pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
4901 maybe_whole!(self, NtBlock, |x| x);
4905 if !self.eat(&token::OpenDelim(token::Brace)) {
4907 let tok = self.this_token_descr();
4908 let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok));
4909 let do_not_suggest_help =
4910 self.token.is_keyword(keywords::In) || self.token == token::Colon;
4912 if self.token.is_ident_named("and") {
4913 e.span_suggestion_short_with_applicability(
4915 "use `&&` instead of `and` for the boolean operator",
4917 Applicability::MaybeIncorrect,
4920 if self.token.is_ident_named("or") {
4921 e.span_suggestion_short_with_applicability(
4923 "use `||` instead of `or` for the boolean operator",
4925 Applicability::MaybeIncorrect,
4929 // Check to see if the user has written something like
4934 // Which is valid in other languages, but not Rust.
4935 match self.parse_stmt_without_recovery(false) {
4937 if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
4938 || do_not_suggest_help {
4939 // if the next token is an open brace (e.g., `if a b {`), the place-
4940 // inside-a-block suggestion would be more likely wrong than right
4941 e.span_label(sp, "expected `{`");
4944 let mut stmt_span = stmt.span;
4945 // expand the span to include the semicolon, if it exists
4946 if self.eat(&token::Semi) {
4947 stmt_span = stmt_span.with_hi(self.prev_span.hi());
4949 let sugg = pprust::to_string(|s| {
4950 use print::pprust::{PrintState, INDENT_UNIT};
4951 s.ibox(INDENT_UNIT)?;
4953 s.print_stmt(&stmt)?;
4954 s.bclose_maybe_open(stmt.span, INDENT_UNIT, false)
4956 e.span_suggestion_with_applicability(
4958 "try placing this code inside a block",
4960 // speculative, has been misleading in the past (closed Issue #46836)
4961 Applicability::MaybeIncorrect
4965 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4966 self.cancel(&mut e);
4970 e.span_label(sp, "expected `{`");
4974 self.parse_block_tail(lo, BlockCheckMode::Default)
4977 /// Parse a block. Inner attrs are allowed.
4978 fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
4979 maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
4982 self.expect(&token::OpenDelim(token::Brace))?;
4983 Ok((self.parse_inner_attributes()?,
4984 self.parse_block_tail(lo, BlockCheckMode::Default)?))
4987 /// Parse the rest of a block expression or function body
4988 /// Precondition: already parsed the '{'.
4989 fn parse_block_tail(&mut self, lo: Span, s: BlockCheckMode) -> PResult<'a, P<Block>> {
4990 let mut stmts = vec![];
4991 while !self.eat(&token::CloseDelim(token::Brace)) {
4992 let stmt = match self.parse_full_stmt(false) {
4995 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
4997 id: ast::DUMMY_NODE_ID,
4998 node: StmtKind::Expr(DummyResult::raw_expr(self.span, true)),
5004 if let Some(stmt) = stmt {
5006 } else if self.token == token::Eof {
5009 // Found only `;` or `}`.
5015 id: ast::DUMMY_NODE_ID,
5017 span: lo.to(self.prev_span),
5021 /// Parse a statement, including the trailing semicolon.
5022 crate fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
5023 // skip looking for a trailing semicolon when we have an interpolated statement
5024 maybe_whole!(self, NtStmt, |x| Some(x));
5026 let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
5028 None => return Ok(None),
5032 StmtKind::Expr(ref expr) if self.token != token::Eof => {
5033 // expression without semicolon
5034 if classify::expr_requires_semi_to_be_stmt(expr) {
5035 // Just check for errors and recover; do not eat semicolon yet.
5037 self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
5040 self.recover_stmt();
5044 StmtKind::Local(..) => {
5045 // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
5046 if macro_legacy_warnings && self.token != token::Semi {
5047 self.warn_missing_semicolon();
5049 self.expect_one_of(&[], &[token::Semi])?;
5055 if self.eat(&token::Semi) {
5056 stmt = stmt.add_trailing_semicolon();
5059 stmt.span = stmt.span.with_hi(self.prev_span.hi());
5063 fn warn_missing_semicolon(&self) {
5064 self.diagnostic().struct_span_warn(self.span, {
5065 &format!("expected `;`, found {}", self.this_token_descr())
5067 "This was erroneously allowed and will become a hard error in a future release"
5071 fn err_dotdotdot_syntax(&self, span: Span) {
5072 self.diagnostic().struct_span_err(span, {
5073 "unexpected token: `...`"
5074 }).span_suggestion_with_applicability(
5075 span, "use `..` for an exclusive range", "..".to_owned(),
5076 Applicability::MaybeIncorrect
5077 ).span_suggestion_with_applicability(
5078 span, "or `..=` for an inclusive range", "..=".to_owned(),
5079 Applicability::MaybeIncorrect
5083 // Parse bounds of a type parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5084 // BOUND = TY_BOUND | LT_BOUND
5085 // LT_BOUND = LIFETIME (e.g., `'a`)
5086 // TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
5087 // TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
5088 fn parse_generic_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, GenericBounds> {
5089 let mut bounds = Vec::new();
5091 // This needs to be synchronized with `Token::can_begin_bound`.
5092 let is_bound_start = self.check_path() || self.check_lifetime() ||
5093 self.check(&token::Question) ||
5094 self.check_keyword(keywords::For) ||
5095 self.check(&token::OpenDelim(token::Paren));
5098 let has_parens = self.eat(&token::OpenDelim(token::Paren));
5099 let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
5100 if self.token.is_lifetime() {
5101 if let Some(question_span) = question {
5102 self.span_err(question_span,
5103 "`?` may only modify trait bounds, not lifetime bounds");
5105 bounds.push(GenericBound::Outlives(self.expect_lifetime()));
5107 self.expect(&token::CloseDelim(token::Paren))?;
5108 self.span_err(self.prev_span,
5109 "parenthesized lifetime bounds are not supported");
5112 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5113 let path = self.parse_path(PathStyle::Type)?;
5115 self.expect(&token::CloseDelim(token::Paren))?;
5117 let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span));
5118 let modifier = if question.is_some() {
5119 TraitBoundModifier::Maybe
5121 TraitBoundModifier::None
5123 bounds.push(GenericBound::Trait(poly_trait, modifier));
5129 if !allow_plus || !self.eat_plus() {
5137 fn parse_generic_bounds(&mut self) -> PResult<'a, GenericBounds> {
5138 self.parse_generic_bounds_common(true)
5141 // Parse bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5142 // BOUND = LT_BOUND (e.g., `'a`)
5143 fn parse_lt_param_bounds(&mut self) -> GenericBounds {
5144 let mut lifetimes = Vec::new();
5145 while self.check_lifetime() {
5146 lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
5148 if !self.eat_plus() {
5155 /// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
5156 fn parse_ty_param(&mut self,
5157 preceding_attrs: Vec<Attribute>)
5158 -> PResult<'a, GenericParam> {
5159 let ident = self.parse_ident()?;
5161 // Parse optional colon and param bounds.
5162 let bounds = if self.eat(&token::Colon) {
5163 self.parse_generic_bounds()?
5168 let default = if self.eat(&token::Eq) {
5169 Some(self.parse_ty()?)
5176 id: ast::DUMMY_NODE_ID,
5177 attrs: preceding_attrs.into(),
5179 kind: GenericParamKind::Type {
5185 /// Parses the following grammar:
5186 /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
5187 fn parse_trait_item_assoc_ty(&mut self)
5188 -> PResult<'a, (Ident, TraitItemKind, ast::Generics)> {
5189 let ident = self.parse_ident()?;
5190 let mut generics = self.parse_generics()?;
5192 // Parse optional colon and param bounds.
5193 let bounds = if self.eat(&token::Colon) {
5194 self.parse_generic_bounds()?
5198 generics.where_clause = self.parse_where_clause()?;
5200 let default = if self.eat(&token::Eq) {
5201 Some(self.parse_ty()?)
5205 self.expect(&token::Semi)?;
5207 Ok((ident, TraitItemKind::Type(bounds, default), generics))
5210 /// Parses (possibly empty) list of lifetime and type parameters, possibly including
5211 /// trailing comma and erroneous trailing attributes.
5212 crate fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
5213 let mut lifetimes = Vec::new();
5214 let mut params = Vec::new();
5215 let mut seen_ty_param: Option<Span> = None;
5216 let mut last_comma_span = None;
5217 let mut bad_lifetime_pos = vec![];
5218 let mut suggestions = vec![];
5220 let attrs = self.parse_outer_attributes()?;
5221 if self.check_lifetime() {
5222 let lifetime = self.expect_lifetime();
5223 // Parse lifetime parameter.
5224 let bounds = if self.eat(&token::Colon) {
5225 self.parse_lt_param_bounds()
5229 lifetimes.push(ast::GenericParam {
5230 ident: lifetime.ident,
5232 attrs: attrs.into(),
5234 kind: ast::GenericParamKind::Lifetime,
5236 if let Some(sp) = seen_ty_param {
5237 let param_span = self.prev_span;
5238 let ate_comma = self.eat(&token::Comma);
5239 let remove_sp = if ate_comma {
5240 param_span.until(self.span)
5242 last_comma_span.unwrap_or(param_span).to(param_span)
5244 bad_lifetime_pos.push(param_span);
5246 if let Ok(snippet) = self.sess.source_map().span_to_snippet(param_span) {
5247 suggestions.push((remove_sp, String::new()));
5248 suggestions.push((sp.shrink_to_lo(), format!("{}, ", snippet)));
5251 last_comma_span = Some(self.prev_span);
5255 } else if self.check_ident() {
5256 // Parse type parameter.
5257 params.push(self.parse_ty_param(attrs)?);
5258 if seen_ty_param.is_none() {
5259 seen_ty_param = Some(self.prev_span);
5262 // Check for trailing attributes and stop parsing.
5263 if !attrs.is_empty() {
5264 let param_kind = if seen_ty_param.is_some() { "type" } else { "lifetime" };
5265 self.struct_span_err(
5267 &format!("trailing attribute after {} parameters", param_kind),
5269 .span_label(attrs[0].span, "attributes must go before parameters")
5275 if !self.eat(&token::Comma) {
5278 last_comma_span = Some(self.prev_span);
5280 if !bad_lifetime_pos.is_empty() {
5281 let mut err = self.struct_span_err(
5283 "lifetime parameters must be declared prior to type parameters",
5285 if !suggestions.is_empty() {
5286 err.multipart_suggestion_with_applicability(
5287 "move the lifetime parameter prior to the first type parameter",
5289 Applicability::MachineApplicable,
5294 lifetimes.extend(params); // ensure the correct order of lifetimes and type params
5298 /// Parse a set of optional generic type parameter declarations. Where
5299 /// clauses are not parsed here, and must be added later via
5300 /// `parse_where_clause()`.
5302 /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
5303 /// | ( < lifetimes , typaramseq ( , )? > )
5304 /// where typaramseq = ( typaram ) | ( typaram , typaramseq )
5305 fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
5306 maybe_whole!(self, NtGenerics, |x| x);
5308 let span_lo = self.span;
5310 let params = self.parse_generic_params()?;
5314 where_clause: WhereClause {
5315 id: ast::DUMMY_NODE_ID,
5316 predicates: Vec::new(),
5317 span: syntax_pos::DUMMY_SP,
5319 span: span_lo.to(self.prev_span),
5322 Ok(ast::Generics::default())
5326 /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
5327 /// possibly including trailing comma.
5328 fn parse_generic_args(&mut self)
5329 -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
5330 let mut args = Vec::new();
5331 let mut bindings = Vec::new();
5332 let mut seen_type = false;
5333 let mut seen_binding = false;
5335 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5336 // Parse lifetime argument.
5337 args.push(GenericArg::Lifetime(self.expect_lifetime()));
5338 if seen_type || seen_binding {
5339 self.struct_span_err(
5341 "lifetime parameters must be declared prior to type parameters"
5343 .span_label(self.prev_span, "must be declared prior to type parameters")
5346 } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
5347 // Parse associated type binding.
5349 let ident = self.parse_ident()?;
5351 let ty = self.parse_ty()?;
5352 bindings.push(TypeBinding {
5353 id: ast::DUMMY_NODE_ID,
5356 span: lo.to(self.prev_span),
5358 seen_binding = true;
5359 } else if self.check_type() {
5360 // Parse type argument.
5361 let ty_param = self.parse_ty()?;
5363 self.struct_span_err(
5365 "type parameters must be declared prior to associated type bindings"
5369 "must be declared prior to associated type bindings",
5373 args.push(GenericArg::Type(ty_param));
5379 if !self.eat(&token::Comma) {
5383 Ok((args, bindings))
5386 /// Parses an optional `where` clause and places it in `generics`.
5388 /// ```ignore (only-for-syntax-highlight)
5389 /// where T : Trait<U, V> + 'b, 'a : 'b
5391 fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
5392 maybe_whole!(self, NtWhereClause, |x| x);
5394 let mut where_clause = WhereClause {
5395 id: ast::DUMMY_NODE_ID,
5396 predicates: Vec::new(),
5397 span: syntax_pos::DUMMY_SP,
5400 if !self.eat_keyword(keywords::Where) {
5401 return Ok(where_clause);
5403 let lo = self.prev_span;
5405 // We are considering adding generics to the `where` keyword as an alternative higher-rank
5406 // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
5407 // change we parse those generics now, but report an error.
5408 if self.choose_generics_over_qpath() {
5409 let generics = self.parse_generics()?;
5410 self.struct_span_err(
5412 "generic parameters on `where` clauses are reserved for future use",
5414 .span_label(generics.span, "currently unsupported")
5420 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5421 let lifetime = self.expect_lifetime();
5422 // Bounds starting with a colon are mandatory, but possibly empty.
5423 self.expect(&token::Colon)?;
5424 let bounds = self.parse_lt_param_bounds();
5425 where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
5426 ast::WhereRegionPredicate {
5427 span: lo.to(self.prev_span),
5432 } else if self.check_type() {
5433 // Parse optional `for<'a, 'b>`.
5434 // This `for` is parsed greedily and applies to the whole predicate,
5435 // the bounded type can have its own `for` applying only to it.
5436 // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/>
5437 // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/>
5438 // Example 3: for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /*ok*/, 'b /*not ok*/>
5439 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5441 // Parse type with mandatory colon and (possibly empty) bounds,
5442 // or with mandatory equality sign and the second type.
5443 let ty = self.parse_ty()?;
5444 if self.eat(&token::Colon) {
5445 let bounds = self.parse_generic_bounds()?;
5446 where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
5447 ast::WhereBoundPredicate {
5448 span: lo.to(self.prev_span),
5449 bound_generic_params: lifetime_defs,
5454 // FIXME: Decide what should be used here, `=` or `==`.
5455 // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
5456 } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
5457 let rhs_ty = self.parse_ty()?;
5458 where_clause.predicates.push(ast::WherePredicate::EqPredicate(
5459 ast::WhereEqPredicate {
5460 span: lo.to(self.prev_span),
5463 id: ast::DUMMY_NODE_ID,
5467 return self.unexpected();
5473 if !self.eat(&token::Comma) {
5478 where_clause.span = lo.to(self.prev_span);
5482 fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
5483 -> PResult<'a, (Vec<Arg> , bool)> {
5484 self.expect(&token::OpenDelim(token::Paren))?;
5487 let mut variadic = false;
5488 let args: Vec<Option<Arg>> =
5489 self.parse_seq_to_before_end(
5490 &token::CloseDelim(token::Paren),
5491 SeqSep::trailing_allowed(token::Comma),
5493 if p.token == token::DotDotDot {
5497 if p.token != token::CloseDelim(token::Paren) {
5500 "`...` must be last in argument list for variadic function");
5504 let span = p.prev_span;
5505 if p.token == token::CloseDelim(token::Paren) {
5506 // continue parsing to present any further errors
5509 "only foreign functions are allowed to be variadic"
5511 Ok(Some(dummy_arg(span)))
5513 // this function definition looks beyond recovery, stop parsing
5515 "only foreign functions are allowed to be variadic");
5520 match p.parse_arg_general(named_args, false) {
5521 Ok(arg) => Ok(Some(arg)),
5524 let lo = p.prev_span;
5525 // Skip every token until next possible arg or end.
5526 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
5527 // Create a placeholder argument for proper arg count (#34264).
5528 let span = lo.to(p.prev_span);
5529 Ok(Some(dummy_arg(span)))
5536 self.eat(&token::CloseDelim(token::Paren));
5538 let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
5540 if variadic && args.is_empty() {
5542 "variadic function must be declared with at least one named argument");
5545 Ok((args, variadic))
5548 /// Parse the argument list and result type of a function declaration
5549 fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
5551 let (args, variadic) = self.parse_fn_args(true, allow_variadic)?;
5552 let ret_ty = self.parse_ret_ty(true)?;
5561 /// Returns the parsed optional self argument and whether a self shortcut was used.
5562 fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
5563 let expect_ident = |this: &mut Self| match this.token {
5564 // Preserve hygienic context.
5565 token::Ident(ident, _) =>
5566 { let span = this.span; this.bump(); Ident::new(ident.name, span) }
5569 let isolated_self = |this: &mut Self, n| {
5570 this.look_ahead(n, |t| t.is_keyword(keywords::SelfLower)) &&
5571 this.look_ahead(n + 1, |t| t != &token::ModSep)
5574 // Parse optional self parameter of a method.
5575 // Only a limited set of initial token sequences is considered self parameters, anything
5576 // else is parsed as a normal function parameter list, so some lookahead is required.
5577 let eself_lo = self.span;
5578 let (eself, eself_ident, eself_hi) = match self.token {
5579 token::BinOp(token::And) => {
5585 (if isolated_self(self, 1) {
5587 SelfKind::Region(None, Mutability::Immutable)
5588 } else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
5589 isolated_self(self, 2) {
5592 SelfKind::Region(None, Mutability::Mutable)
5593 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5594 isolated_self(self, 2) {
5596 let lt = self.expect_lifetime();
5597 SelfKind::Region(Some(lt), Mutability::Immutable)
5598 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5599 self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
5600 isolated_self(self, 3) {
5602 let lt = self.expect_lifetime();
5604 SelfKind::Region(Some(lt), Mutability::Mutable)
5607 }, expect_ident(self), self.prev_span)
5609 token::BinOp(token::Star) => {
5614 // Emit special error for `self` cases.
5615 (if isolated_self(self, 1) {
5617 self.span_err(self.span, "cannot pass `self` by raw pointer");
5618 SelfKind::Value(Mutability::Immutable)
5619 } else if self.look_ahead(1, |t| t.is_mutability()) &&
5620 isolated_self(self, 2) {
5623 self.span_err(self.span, "cannot pass `self` by raw pointer");
5624 SelfKind::Value(Mutability::Immutable)
5627 }, expect_ident(self), self.prev_span)
5629 token::Ident(..) => {
5630 if isolated_self(self, 0) {
5633 let eself_ident = expect_ident(self);
5634 let eself_hi = self.prev_span;
5635 (if self.eat(&token::Colon) {
5636 let ty = self.parse_ty()?;
5637 SelfKind::Explicit(ty, Mutability::Immutable)
5639 SelfKind::Value(Mutability::Immutable)
5640 }, eself_ident, eself_hi)
5641 } else if self.token.is_keyword(keywords::Mut) &&
5642 isolated_self(self, 1) {
5646 let eself_ident = expect_ident(self);
5647 let eself_hi = self.prev_span;
5648 (if self.eat(&token::Colon) {
5649 let ty = self.parse_ty()?;
5650 SelfKind::Explicit(ty, Mutability::Mutable)
5652 SelfKind::Value(Mutability::Mutable)
5653 }, eself_ident, eself_hi)
5658 _ => return Ok(None),
5661 let eself = source_map::respan(eself_lo.to(eself_hi), eself);
5662 Ok(Some(Arg::from_self(eself, eself_ident)))
5665 /// Parse the parameter list and result type of a function that may have a `self` parameter.
5666 fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>>
5667 where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
5669 self.expect(&token::OpenDelim(token::Paren))?;
5671 // Parse optional self argument
5672 let self_arg = self.parse_self_arg()?;
5674 // Parse the rest of the function parameter list.
5675 let sep = SeqSep::trailing_allowed(token::Comma);
5676 let fn_inputs = if let Some(self_arg) = self_arg {
5677 if self.check(&token::CloseDelim(token::Paren)) {
5679 } else if self.eat(&token::Comma) {
5680 let mut fn_inputs = vec![self_arg];
5681 fn_inputs.append(&mut self.parse_seq_to_before_end(
5682 &token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5686 return self.unexpected();
5689 self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5692 // Parse closing paren and return type.
5693 self.expect(&token::CloseDelim(token::Paren))?;
5696 output: self.parse_ret_ty(true)?,
5701 // parse the |arg, arg| header on a lambda
5702 fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
5703 let inputs_captures = {
5704 if self.eat(&token::OrOr) {
5707 self.expect(&token::BinOp(token::Or))?;
5708 let args = self.parse_seq_to_before_tokens(
5709 &[&token::BinOp(token::Or), &token::OrOr],
5710 SeqSep::trailing_allowed(token::Comma),
5711 TokenExpectType::NoExpect,
5712 |p| p.parse_fn_block_arg()
5718 let output = self.parse_ret_ty(true)?;
5721 inputs: inputs_captures,
5727 /// Parse the name and optional generic types of a function header.
5728 fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
5729 let id = self.parse_ident()?;
5730 let generics = self.parse_generics()?;
5734 fn mk_item(&mut self, span: Span, ident: Ident, node: ItemKind, vis: Visibility,
5735 attrs: Vec<Attribute>) -> P<Item> {
5739 id: ast::DUMMY_NODE_ID,
5747 /// Parse an item-position function declaration.
5748 fn parse_item_fn(&mut self,
5751 constness: Spanned<Constness>,
5753 -> PResult<'a, ItemInfo> {
5754 let (ident, mut generics) = self.parse_fn_header()?;
5755 let decl = self.parse_fn_decl(false)?;
5756 generics.where_clause = self.parse_where_clause()?;
5757 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5758 let header = FnHeader { unsafety, asyncness, constness, abi };
5759 Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
5762 /// true if we are looking at `const ID`, false for things like `const fn` etc
5763 fn is_const_item(&mut self) -> bool {
5764 self.token.is_keyword(keywords::Const) &&
5765 !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
5766 !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
5769 /// parses all the "front matter" for a `fn` declaration, up to
5770 /// and including the `fn` keyword:
5774 /// - `const unsafe fn`
5777 fn parse_fn_front_matter(&mut self)
5785 let is_const_fn = self.eat_keyword(keywords::Const);
5786 let const_span = self.prev_span;
5787 let unsafety = self.parse_unsafety();
5788 let asyncness = self.parse_asyncness();
5789 let (constness, unsafety, abi) = if is_const_fn {
5790 (respan(const_span, Constness::Const), unsafety, Abi::Rust)
5792 let abi = if self.eat_keyword(keywords::Extern) {
5793 self.parse_opt_abi()?.unwrap_or(Abi::C)
5797 (respan(self.prev_span, Constness::NotConst), unsafety, abi)
5799 self.expect_keyword(keywords::Fn)?;
5800 Ok((constness, unsafety, asyncness, abi))
5803 /// Parse an impl item.
5804 pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
5805 maybe_whole!(self, NtImplItem, |x| x);
5806 let attrs = self.parse_outer_attributes()?;
5807 let (mut item, tokens) = self.collect_tokens(|this| {
5808 this.parse_impl_item_(at_end, attrs)
5811 // See `parse_item` for why this clause is here.
5812 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
5813 item.tokens = Some(tokens);
5818 fn parse_impl_item_(&mut self,
5820 mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> {
5822 let vis = self.parse_visibility(false)?;
5823 let defaultness = self.parse_defaultness();
5824 let (name, node, generics) = if let Some(type_) = self.eat_type() {
5825 let (name, alias, generics) = type_?;
5826 let kind = match alias {
5827 AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ),
5828 AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds),
5830 (name, kind, generics)
5831 } else if self.is_const_item() {
5832 // This parses the grammar:
5833 // ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
5834 self.expect_keyword(keywords::Const)?;
5835 let name = self.parse_ident()?;
5836 self.expect(&token::Colon)?;
5837 let typ = self.parse_ty()?;
5838 self.expect(&token::Eq)?;
5839 let expr = self.parse_expr()?;
5840 self.expect(&token::Semi)?;
5841 (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default())
5843 let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?;
5844 attrs.extend(inner_attrs);
5845 (name, node, generics)
5849 id: ast::DUMMY_NODE_ID,
5850 span: lo.to(self.prev_span),
5861 fn complain_if_pub_macro(&mut self, vis: &VisibilityKind, sp: Span) {
5863 VisibilityKind::Inherited => {}
5865 let is_macro_rules: bool = match self.token {
5866 token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"),
5869 let mut err = if is_macro_rules {
5870 let mut err = self.diagnostic()
5871 .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
5872 err.span_suggestion_with_applicability(
5874 "try exporting the macro",
5875 "#[macro_export]".to_owned(),
5876 Applicability::MaybeIncorrect // speculative
5880 let mut err = self.diagnostic()
5881 .struct_span_err(sp, "can't qualify macro invocation with `pub`");
5882 err.help("try adjusting the macro to put `pub` inside the invocation");
5890 fn missing_assoc_item_kind_err(&mut self, item_type: &str, prev_span: Span)
5891 -> DiagnosticBuilder<'a>
5893 let expected_kinds = if item_type == "extern" {
5894 "missing `fn`, `type`, or `static`"
5896 "missing `fn`, `type`, or `const`"
5899 // Given this code `path(`, it seems like this is not
5900 // setting the visibility of a macro invocation, but rather
5901 // a mistyped method declaration.
5902 // Create a diagnostic pointing out that `fn` is missing.
5904 // x | pub path(&self) {
5905 // | ^ missing `fn`, `type`, or `const`
5907 // ^^ `sp` below will point to this
5908 let sp = prev_span.between(self.prev_span);
5909 let mut err = self.diagnostic().struct_span_err(
5911 &format!("{} for {}-item declaration",
5912 expected_kinds, item_type));
5913 err.span_label(sp, expected_kinds);
5917 /// Parse a method or a macro invocation in a trait impl.
5918 fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
5919 -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics,
5920 ast::ImplItemKind)> {
5921 // code copied from parse_macro_use_or_failure... abstraction!
5922 if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
5924 Ok((keywords::Invalid.ident(), vec![], ast::Generics::default(),
5925 ast::ImplItemKind::Macro(mac)))
5927 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
5928 let ident = self.parse_ident()?;
5929 let mut generics = self.parse_generics()?;
5930 let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
5931 generics.where_clause = self.parse_where_clause()?;
5933 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5934 let header = ast::FnHeader { abi, unsafety, constness, asyncness };
5935 Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
5936 ast::MethodSig { header, decl },
5942 /// Parse `trait Foo { ... }` or `trait Foo = Bar;`
5943 fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5944 let ident = self.parse_ident()?;
5945 let mut tps = self.parse_generics()?;
5947 // Parse optional colon and supertrait bounds.
5948 let bounds = if self.eat(&token::Colon) {
5949 self.parse_generic_bounds()?
5954 if self.eat(&token::Eq) {
5955 // it's a trait alias
5956 let bounds = self.parse_generic_bounds()?;
5957 tps.where_clause = self.parse_where_clause()?;
5958 self.expect(&token::Semi)?;
5959 if unsafety != Unsafety::Normal {
5960 self.span_err(self.prev_span, "trait aliases cannot be unsafe");
5962 Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
5964 // it's a normal trait
5965 tps.where_clause = self.parse_where_clause()?;
5966 self.expect(&token::OpenDelim(token::Brace))?;
5967 let mut trait_items = vec![];
5968 while !self.eat(&token::CloseDelim(token::Brace)) {
5969 let mut at_end = false;
5970 match self.parse_trait_item(&mut at_end) {
5971 Ok(item) => trait_items.push(item),
5975 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5980 Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
5984 fn choose_generics_over_qpath(&self) -> bool {
5985 // There's an ambiguity between generic parameters and qualified paths in impls.
5986 // If we see `<` it may start both, so we have to inspect some following tokens.
5987 // The following combinations can only start generics,
5988 // but not qualified paths (with one exception):
5989 // `<` `>` - empty generic parameters
5990 // `<` `#` - generic parameters with attributes
5991 // `<` (LIFETIME|IDENT) `>` - single generic parameter
5992 // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
5993 // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
5994 // `<` (LIFETIME|IDENT) `=` - generic parameter with a default
5995 // The only truly ambiguous case is
5996 // `<` IDENT `>` `::` IDENT ...
5997 // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
5998 // because this is what almost always expected in practice, qualified paths in impls
5999 // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
6000 self.token == token::Lt &&
6001 (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
6002 self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
6003 self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
6004 t == &token::Colon || t == &token::Eq))
6007 fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
6008 self.expect(&token::OpenDelim(token::Brace))?;
6009 let attrs = self.parse_inner_attributes()?;
6011 let mut impl_items = Vec::new();
6012 while !self.eat(&token::CloseDelim(token::Brace)) {
6013 let mut at_end = false;
6014 match self.parse_impl_item(&mut at_end) {
6015 Ok(impl_item) => impl_items.push(impl_item),
6019 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
6024 Ok((impl_items, attrs))
6027 /// Parses an implementation item, `impl` keyword is already parsed.
6028 /// impl<'a, T> TYPE { /* impl items */ }
6029 /// impl<'a, T> TRAIT for TYPE { /* impl items */ }
6030 /// impl<'a, T> !TRAIT for TYPE { /* impl items */ }
6031 /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
6032 /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
6033 /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
6034 fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
6035 -> PResult<'a, ItemInfo> {
6036 // First, parse generic parameters if necessary.
6037 let mut generics = if self.choose_generics_over_qpath() {
6038 self.parse_generics()?
6040 ast::Generics::default()
6043 // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
6044 let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
6046 ast::ImplPolarity::Negative
6048 ast::ImplPolarity::Positive
6051 // Parse both types and traits as a type, then reinterpret if necessary.
6052 let ty_first = self.parse_ty()?;
6054 // If `for` is missing we try to recover.
6055 let has_for = self.eat_keyword(keywords::For);
6056 let missing_for_span = self.prev_span.between(self.span);
6058 let ty_second = if self.token == token::DotDot {
6059 // We need to report this error after `cfg` expansion for compatibility reasons
6060 self.bump(); // `..`, do not add it to expected tokens
6061 Some(P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID }))
6062 } else if has_for || self.token.can_begin_type() {
6063 Some(self.parse_ty()?)
6068 generics.where_clause = self.parse_where_clause()?;
6070 let (impl_items, attrs) = self.parse_impl_body()?;
6072 let item_kind = match ty_second {
6073 Some(ty_second) => {
6074 // impl Trait for Type
6076 self.struct_span_err(missing_for_span, "missing `for` in a trait impl")
6077 .span_suggestion_short_with_applicability(
6080 " for ".to_string(),
6081 Applicability::MachineApplicable,
6085 let ty_first = ty_first.into_inner();
6086 let path = match ty_first.node {
6087 // This notably includes paths passed through `ty` macro fragments (#46438).
6088 TyKind::Path(None, path) => path,
6090 self.span_err(ty_first.span, "expected a trait, found type");
6091 ast::Path::from_ident(Ident::new(keywords::Invalid.name(), ty_first.span))
6094 let trait_ref = TraitRef { path, ref_id: ty_first.id };
6096 ItemKind::Impl(unsafety, polarity, defaultness,
6097 generics, Some(trait_ref), ty_second, impl_items)
6101 ItemKind::Impl(unsafety, polarity, defaultness,
6102 generics, None, ty_first, impl_items)
6106 Ok((keywords::Invalid.ident(), item_kind, Some(attrs)))
6109 fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
6110 if self.eat_keyword(keywords::For) {
6112 let params = self.parse_generic_params()?;
6114 // We rely on AST validation to rule out invalid cases: There must not be type
6115 // parameters, and the lifetime parameters must not have bounds.
6122 /// Parse struct Foo { ... }
6123 fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
6124 let class_name = self.parse_ident()?;
6126 let mut generics = self.parse_generics()?;
6128 // There is a special case worth noting here, as reported in issue #17904.
6129 // If we are parsing a tuple struct it is the case that the where clause
6130 // should follow the field list. Like so:
6132 // struct Foo<T>(T) where T: Copy;
6134 // If we are parsing a normal record-style struct it is the case
6135 // that the where clause comes before the body, and after the generics.
6136 // So if we look ahead and see a brace or a where-clause we begin
6137 // parsing a record style struct.
6139 // Otherwise if we look ahead and see a paren we parse a tuple-style
6142 let vdata = if self.token.is_keyword(keywords::Where) {
6143 generics.where_clause = self.parse_where_clause()?;
6144 if self.eat(&token::Semi) {
6145 // If we see a: `struct Foo<T> where T: Copy;` style decl.
6146 VariantData::Unit(ast::DUMMY_NODE_ID)
6148 // If we see: `struct Foo<T> where T: Copy { ... }`
6149 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6151 // No `where` so: `struct Foo<T>;`
6152 } else if self.eat(&token::Semi) {
6153 VariantData::Unit(ast::DUMMY_NODE_ID)
6154 // Record-style struct definition
6155 } else if self.token == token::OpenDelim(token::Brace) {
6156 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6157 // Tuple-style struct definition with optional where-clause.
6158 } else if self.token == token::OpenDelim(token::Paren) {
6159 let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID);
6160 generics.where_clause = self.parse_where_clause()?;
6161 self.expect(&token::Semi)?;
6164 let token_str = self.this_token_descr();
6165 let mut err = self.fatal(&format!(
6166 "expected `where`, `{{`, `(`, or `;` after struct name, found {}",
6169 err.span_label(self.span, "expected `where`, `{`, `(`, or `;` after struct name");
6173 Ok((class_name, ItemKind::Struct(vdata, generics), None))
6176 /// Parse union Foo { ... }
6177 fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
6178 let class_name = self.parse_ident()?;
6180 let mut generics = self.parse_generics()?;
6182 let vdata = if self.token.is_keyword(keywords::Where) {
6183 generics.where_clause = self.parse_where_clause()?;
6184 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6185 } else if self.token == token::OpenDelim(token::Brace) {
6186 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6188 let token_str = self.this_token_descr();
6189 let mut err = self.fatal(&format!(
6190 "expected `where` or `{{` after union name, found {}", token_str));
6191 err.span_label(self.span, "expected `where` or `{` after union name");
6195 Ok((class_name, ItemKind::Union(vdata, generics), None))
6198 fn consume_block(&mut self, delim: token::DelimToken) {
6199 let mut brace_depth = 0;
6201 if self.eat(&token::OpenDelim(delim)) {
6203 } else if self.eat(&token::CloseDelim(delim)) {
6204 if brace_depth == 0 {
6210 } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
6218 fn parse_record_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6219 let mut fields = Vec::new();
6220 if self.eat(&token::OpenDelim(token::Brace)) {
6221 while self.token != token::CloseDelim(token::Brace) {
6222 let field = self.parse_struct_decl_field().map_err(|e| {
6223 self.recover_stmt();
6227 Ok(field) => fields.push(field),
6233 self.eat(&token::CloseDelim(token::Brace));
6235 let token_str = self.this_token_descr();
6236 let mut err = self.fatal(&format!(
6237 "expected `where`, or `{{` after struct name, found {}", token_str));
6238 err.span_label(self.span, "expected `where`, or `{` after struct name");
6245 fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6246 // This is the case where we find `struct Foo<T>(T) where T: Copy;`
6247 // Unit like structs are handled in parse_item_struct function
6248 let fields = self.parse_unspanned_seq(
6249 &token::OpenDelim(token::Paren),
6250 &token::CloseDelim(token::Paren),
6251 SeqSep::trailing_allowed(token::Comma),
6253 let attrs = p.parse_outer_attributes()?;
6255 let vis = p.parse_visibility(true)?;
6256 let ty = p.parse_ty()?;
6258 span: lo.to(ty.span),
6261 id: ast::DUMMY_NODE_ID,
6270 /// Parse a structure field declaration
6271 fn parse_single_struct_field(&mut self,
6274 attrs: Vec<Attribute> )
6275 -> PResult<'a, StructField> {
6276 let mut seen_comma: bool = false;
6277 let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
6278 if self.token == token::Comma {
6285 token::CloseDelim(token::Brace) => {}
6286 token::DocComment(_) => {
6287 let previous_span = self.prev_span;
6288 let mut err = self.span_fatal_err(self.span, Error::UselessDocComment);
6289 self.bump(); // consume the doc comment
6290 let comma_after_doc_seen = self.eat(&token::Comma);
6291 // `seen_comma` is always false, because we are inside doc block
6292 // condition is here to make code more readable
6293 if seen_comma == false && comma_after_doc_seen == true {
6296 if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
6299 if seen_comma == false {
6300 let sp = self.sess.source_map().next_point(previous_span);
6301 err.span_suggestion_with_applicability(
6303 "missing comma here",
6305 Applicability::MachineApplicable
6312 let sp = self.sess.source_map().next_point(self.prev_span);
6313 let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}",
6314 self.this_token_descr()));
6315 if self.token.is_ident() {
6316 // This is likely another field; emit the diagnostic and keep going
6317 err.span_suggestion_with_applicability(
6319 "try adding a comma",
6321 Applicability::MachineApplicable,
6332 /// Parse an element of a struct definition
6333 fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
6334 let attrs = self.parse_outer_attributes()?;
6336 let vis = self.parse_visibility(false)?;
6337 self.parse_single_struct_field(lo, vis, attrs)
6340 /// Parse `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
6341 /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
6342 /// If the following element can't be a tuple (i.e., it's a function definition,
6343 /// it's not a tuple struct field) and the contents within the parens
6344 /// isn't valid, emit a proper diagnostic.
6345 pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
6346 maybe_whole!(self, NtVis, |x| x);
6348 self.expected_tokens.push(TokenType::Keyword(keywords::Crate));
6349 if self.is_crate_vis() {
6350 self.bump(); // `crate`
6351 return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
6354 if !self.eat_keyword(keywords::Pub) {
6355 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
6356 // keyword to grab a span from for inherited visibility; an empty span at the
6357 // beginning of the current token would seem to be the "Schelling span".
6358 return Ok(respan(self.span.shrink_to_lo(), VisibilityKind::Inherited))
6360 let lo = self.prev_span;
6362 if self.check(&token::OpenDelim(token::Paren)) {
6363 // We don't `self.bump()` the `(` yet because this might be a struct definition where
6364 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
6365 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
6366 // by the following tokens.
6367 if self.look_ahead(1, |t| t.is_keyword(keywords::Crate)) {
6370 self.bump(); // `crate`
6371 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6373 lo.to(self.prev_span),
6374 VisibilityKind::Crate(CrateSugar::PubCrate),
6377 } else if self.look_ahead(1, |t| t.is_keyword(keywords::In)) {
6380 self.bump(); // `in`
6381 let path = self.parse_path(PathStyle::Mod)?; // `path`
6382 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6383 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6385 id: ast::DUMMY_NODE_ID,
6388 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
6389 self.look_ahead(1, |t| t.is_keyword(keywords::Super) ||
6390 t.is_keyword(keywords::SelfLower))
6392 // `pub(self)` or `pub(super)`
6394 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
6395 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6396 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6398 id: ast::DUMMY_NODE_ID,
6401 } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct
6402 // `pub(something) fn ...` or `struct X { pub(something) y: Z }`
6404 let msg = "incorrect visibility restriction";
6405 let suggestion = r##"some possible visibility restrictions are:
6406 `pub(crate)`: visible only on the current crate
6407 `pub(super)`: visible only in the current module's parent
6408 `pub(in path::to::module)`: visible only on the specified path"##;
6409 let path = self.parse_path(PathStyle::Mod)?;
6410 let sp = self.prev_span;
6411 let help_msg = format!("make this visible only to module `{}` with `in`", path);
6412 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6413 let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg);
6414 err.help(suggestion);
6415 err.span_suggestion_with_applicability(
6416 sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable
6418 err.emit(); // emit diagnostic, but continue with public visibility
6422 Ok(respan(lo, VisibilityKind::Public))
6425 /// Parse defaultness: `default` or nothing.
6426 fn parse_defaultness(&mut self) -> Defaultness {
6427 // `pub` is included for better error messages
6428 if self.check_keyword(keywords::Default) &&
6429 self.look_ahead(1, |t| t.is_keyword(keywords::Impl) ||
6430 t.is_keyword(keywords::Const) ||
6431 t.is_keyword(keywords::Fn) ||
6432 t.is_keyword(keywords::Unsafe) ||
6433 t.is_keyword(keywords::Extern) ||
6434 t.is_keyword(keywords::Type) ||
6435 t.is_keyword(keywords::Pub)) {
6436 self.bump(); // `default`
6437 Defaultness::Default
6443 /// Given a termination token, parse all of the items in a module
6444 fn parse_mod_items(&mut self, term: &token::Token, inner_lo: Span) -> PResult<'a, Mod> {
6445 let mut items = vec![];
6446 while let Some(item) = self.parse_item()? {
6450 if !self.eat(term) {
6451 let token_str = self.this_token_descr();
6452 let mut err = self.fatal(&format!("expected item, found {}", token_str));
6453 if self.token == token::Semi {
6454 let msg = "consider removing this semicolon";
6455 err.span_suggestion_short_with_applicability(
6456 self.span, msg, String::new(), Applicability::MachineApplicable
6458 if !items.is_empty() { // Issue #51603
6459 let previous_item = &items[items.len()-1];
6460 let previous_item_kind_name = match previous_item.node {
6461 // say "braced struct" because tuple-structs and
6462 // braceless-empty-struct declarations do take a semicolon
6463 ItemKind::Struct(..) => Some("braced struct"),
6464 ItemKind::Enum(..) => Some("enum"),
6465 ItemKind::Trait(..) => Some("trait"),
6466 ItemKind::Union(..) => Some("union"),
6469 if let Some(name) = previous_item_kind_name {
6470 err.help(&format!("{} declarations are not followed by a semicolon",
6475 err.span_label(self.span, "expected item");
6480 let hi = if self.span.is_dummy() {
6487 inner: inner_lo.to(hi),
6493 fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
6494 let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?;
6495 self.expect(&token::Colon)?;
6496 let ty = self.parse_ty()?;
6497 self.expect(&token::Eq)?;
6498 let e = self.parse_expr()?;
6499 self.expect(&token::Semi)?;
6500 let item = match m {
6501 Some(m) => ItemKind::Static(ty, m, e),
6502 None => ItemKind::Const(ty, e),
6504 Ok((id, item, None))
6507 /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
6508 fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
6509 let (in_cfg, outer_attrs) = {
6510 let mut strip_unconfigured = ::config::StripUnconfigured {
6512 features: None, // don't perform gated feature checking
6514 let outer_attrs = strip_unconfigured.process_cfg_attrs(outer_attrs.to_owned());
6515 (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), outer_attrs)
6518 let id_span = self.span;
6519 let id = self.parse_ident()?;
6520 if self.eat(&token::Semi) {
6521 if in_cfg && self.recurse_into_file_modules {
6522 // This mod is in an external file. Let's go get it!
6523 let ModulePathSuccess { path, directory_ownership, warn } =
6524 self.submod_path(id, &outer_attrs, id_span)?;
6525 let (module, mut attrs) =
6526 self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
6527 // Record that we fetched the mod from an external file
6529 let attr = Attribute {
6530 id: attr::mk_attr_id(),
6531 style: ast::AttrStyle::Outer,
6532 path: ast::Path::from_ident(Ident::from_str("warn_directory_ownership")),
6533 tokens: TokenStream::empty(),
6534 is_sugared_doc: false,
6535 span: syntax_pos::DUMMY_SP,
6537 attr::mark_known(&attr);
6540 Ok((id, ItemKind::Mod(module), Some(attrs)))
6542 let placeholder = ast::Mod {
6543 inner: syntax_pos::DUMMY_SP,
6547 Ok((id, ItemKind::Mod(placeholder), None))
6550 let old_directory = self.directory.clone();
6551 self.push_directory(id, &outer_attrs);
6553 self.expect(&token::OpenDelim(token::Brace))?;
6554 let mod_inner_lo = self.span;
6555 let attrs = self.parse_inner_attributes()?;
6556 let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
6558 self.directory = old_directory;
6559 Ok((id, ItemKind::Mod(module), Some(attrs)))
6563 fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
6564 if let Some(path) = attr::first_attr_value_str_by_name(attrs, "path") {
6565 self.directory.path.to_mut().push(&path.as_str());
6566 self.directory.ownership = DirectoryOwnership::Owned { relative: None };
6568 // We have to push on the current module name in the case of relative
6569 // paths in order to ensure that any additional module paths from inline
6570 // `mod x { ... }` come after the relative extension.
6572 // For example, a `mod z { ... }` inside `x/y.rs` should set the current
6573 // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
6574 if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
6575 if let Some(ident) = relative.take() { // remove the relative offset
6576 self.directory.path.to_mut().push(ident.as_str());
6579 self.directory.path.to_mut().push(&id.as_str());
6583 pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
6584 if let Some(s) = attr::first_attr_value_str_by_name(attrs, "path") {
6587 // On windows, the base path might have the form
6588 // `\\?\foo\bar` in which case it does not tolerate
6589 // mixed `/` and `\` separators, so canonicalize
6592 let s = s.replace("/", "\\");
6593 Some(dir_path.join(s))
6599 /// Returns either a path to a module, or .
6600 pub fn default_submod_path(
6602 relative: Option<ast::Ident>,
6604 source_map: &SourceMap) -> ModulePath
6606 // If we're in a foo.rs file instead of a mod.rs file,
6607 // we need to look for submodules in
6608 // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
6609 // `./<id>.rs` and `./<id>/mod.rs`.
6610 let relative_prefix_string;
6611 let relative_prefix = if let Some(ident) = relative {
6612 relative_prefix_string = format!("{}{}", ident.as_str(), path::MAIN_SEPARATOR);
6613 &relative_prefix_string
6618 let mod_name = id.to_string();
6619 let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
6620 let secondary_path_str = format!("{}{}{}mod.rs",
6621 relative_prefix, mod_name, path::MAIN_SEPARATOR);
6622 let default_path = dir_path.join(&default_path_str);
6623 let secondary_path = dir_path.join(&secondary_path_str);
6624 let default_exists = source_map.file_exists(&default_path);
6625 let secondary_exists = source_map.file_exists(&secondary_path);
6627 let result = match (default_exists, secondary_exists) {
6628 (true, false) => Ok(ModulePathSuccess {
6630 directory_ownership: DirectoryOwnership::Owned {
6635 (false, true) => Ok(ModulePathSuccess {
6636 path: secondary_path,
6637 directory_ownership: DirectoryOwnership::Owned {
6642 (false, false) => Err(Error::FileNotFoundForModule {
6643 mod_name: mod_name.clone(),
6644 default_path: default_path_str,
6645 secondary_path: secondary_path_str,
6646 dir_path: dir_path.display().to_string(),
6648 (true, true) => Err(Error::DuplicatePaths {
6649 mod_name: mod_name.clone(),
6650 default_path: default_path_str,
6651 secondary_path: secondary_path_str,
6657 path_exists: default_exists || secondary_exists,
6662 fn submod_path(&mut self,
6664 outer_attrs: &[Attribute],
6666 -> PResult<'a, ModulePathSuccess> {
6667 if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
6668 return Ok(ModulePathSuccess {
6669 directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
6670 // All `#[path]` files are treated as though they are a `mod.rs` file.
6671 // This means that `mod foo;` declarations inside `#[path]`-included
6672 // files are siblings,
6674 // Note that this will produce weirdness when a file named `foo.rs` is
6675 // `#[path]` included and contains a `mod foo;` declaration.
6676 // If you encounter this, it's your own darn fault :P
6677 Some(_) => DirectoryOwnership::Owned { relative: None },
6678 _ => DirectoryOwnership::UnownedViaMod(true),
6685 let relative = match self.directory.ownership {
6686 DirectoryOwnership::Owned { relative } => relative,
6687 DirectoryOwnership::UnownedViaBlock |
6688 DirectoryOwnership::UnownedViaMod(_) => None,
6690 let paths = Parser::default_submod_path(
6691 id, relative, &self.directory.path, self.sess.source_map());
6693 match self.directory.ownership {
6694 DirectoryOwnership::Owned { .. } => {
6695 paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
6697 DirectoryOwnership::UnownedViaBlock => {
6699 "Cannot declare a non-inline module inside a block \
6700 unless it has a path attribute";
6701 let mut err = self.diagnostic().struct_span_err(id_sp, msg);
6702 if paths.path_exists {
6703 let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
6705 err.span_note(id_sp, &msg);
6709 DirectoryOwnership::UnownedViaMod(warn) => {
6711 if let Ok(result) = paths.result {
6712 return Ok(ModulePathSuccess { warn: true, ..result });
6715 let mut err = self.diagnostic().struct_span_err(id_sp,
6716 "cannot declare a new module at this location");
6717 if !id_sp.is_dummy() {
6718 let src_path = self.sess.source_map().span_to_filename(id_sp);
6719 if let FileName::Real(src_path) = src_path {
6720 if let Some(stem) = src_path.file_stem() {
6721 let mut dest_path = src_path.clone();
6722 dest_path.set_file_name(stem);
6723 dest_path.push("mod.rs");
6724 err.span_note(id_sp,
6725 &format!("maybe move this module `{}` to its own \
6726 directory via `{}`", src_path.display(),
6727 dest_path.display()));
6731 if paths.path_exists {
6732 err.span_note(id_sp,
6733 &format!("... or maybe `use` the module `{}` instead \
6734 of possibly redeclaring it",
6742 /// Read a module from a source file.
6743 fn eval_src_mod(&mut self,
6745 directory_ownership: DirectoryOwnership,
6748 -> PResult<'a, (ast::Mod, Vec<Attribute> )> {
6749 let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
6750 if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
6751 let mut err = String::from("circular modules: ");
6752 let len = included_mod_stack.len();
6753 for p in &included_mod_stack[i.. len] {
6754 err.push_str(&p.to_string_lossy());
6755 err.push_str(" -> ");
6757 err.push_str(&path.to_string_lossy());
6758 return Err(self.span_fatal(id_sp, &err[..]));
6760 included_mod_stack.push(path.clone());
6761 drop(included_mod_stack);
6764 new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
6765 p0.cfg_mods = self.cfg_mods;
6766 let mod_inner_lo = p0.span;
6767 let mod_attrs = p0.parse_inner_attributes()?;
6768 let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
6770 self.sess.included_mod_stack.borrow_mut().pop();
6774 /// Parse a function declaration from a foreign module
6775 fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6776 -> PResult<'a, ForeignItem> {
6777 self.expect_keyword(keywords::Fn)?;
6779 let (ident, mut generics) = self.parse_fn_header()?;
6780 let decl = self.parse_fn_decl(true)?;
6781 generics.where_clause = self.parse_where_clause()?;
6783 self.expect(&token::Semi)?;
6784 Ok(ast::ForeignItem {
6787 node: ForeignItemKind::Fn(decl, generics),
6788 id: ast::DUMMY_NODE_ID,
6794 /// Parse a static item from a foreign module.
6795 /// Assumes that the `static` keyword is already parsed.
6796 fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6797 -> PResult<'a, ForeignItem> {
6798 let mutbl = self.eat_keyword(keywords::Mut);
6799 let ident = self.parse_ident()?;
6800 self.expect(&token::Colon)?;
6801 let ty = self.parse_ty()?;
6803 self.expect(&token::Semi)?;
6807 node: ForeignItemKind::Static(ty, mutbl),
6808 id: ast::DUMMY_NODE_ID,
6814 /// Parse a type from a foreign module
6815 fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6816 -> PResult<'a, ForeignItem> {
6817 self.expect_keyword(keywords::Type)?;
6819 let ident = self.parse_ident()?;
6821 self.expect(&token::Semi)?;
6822 Ok(ast::ForeignItem {
6825 node: ForeignItemKind::Ty,
6826 id: ast::DUMMY_NODE_ID,
6832 fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
6833 let error_msg = "crate name using dashes are not valid in `extern crate` statements";
6834 let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
6836 let mut ident = if self.token.is_keyword(keywords::SelfLower) {
6837 self.parse_path_segment_ident()
6841 let mut idents = vec![];
6842 let mut replacement = vec![];
6843 let mut fixed_crate_name = false;
6844 // Accept `extern crate name-like-this` for better diagnostics
6845 let dash = token::Token::BinOp(token::BinOpToken::Minus);
6846 if self.token == dash { // Do not include `-` as part of the expected tokens list
6847 while self.eat(&dash) {
6848 fixed_crate_name = true;
6849 replacement.push((self.prev_span, "_".to_string()));
6850 idents.push(self.parse_ident()?);
6853 if fixed_crate_name {
6854 let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
6855 let mut fixed_name = format!("{}", ident.name);
6856 for part in idents {
6857 fixed_name.push_str(&format!("_{}", part.name));
6859 ident = Ident::from_str(&fixed_name).with_span_pos(fixed_name_sp);
6861 let mut err = self.struct_span_err(fixed_name_sp, error_msg);
6862 err.span_label(fixed_name_sp, "dash-separated idents are not valid");
6863 err.multipart_suggestion(suggestion_msg, replacement);
6869 /// Parse extern crate links
6873 /// extern crate foo;
6874 /// extern crate bar as foo;
6875 fn parse_item_extern_crate(&mut self,
6877 visibility: Visibility,
6878 attrs: Vec<Attribute>)
6879 -> PResult<'a, P<Item>> {
6880 // Accept `extern crate name-like-this` for better diagnostics
6881 let orig_name = self.parse_crate_name_with_dashes()?;
6882 let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
6883 (rename, Some(orig_name.name))
6887 self.expect(&token::Semi)?;
6889 let span = lo.to(self.prev_span);
6890 Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
6893 /// Parse `extern` for foreign ABIs
6896 /// `extern` is expected to have been
6897 /// consumed before calling this method
6903 fn parse_item_foreign_mod(&mut self,
6905 opt_abi: Option<Abi>,
6906 visibility: Visibility,
6907 mut attrs: Vec<Attribute>)
6908 -> PResult<'a, P<Item>> {
6909 self.expect(&token::OpenDelim(token::Brace))?;
6911 let abi = opt_abi.unwrap_or(Abi::C);
6913 attrs.extend(self.parse_inner_attributes()?);
6915 let mut foreign_items = vec![];
6916 while !self.eat(&token::CloseDelim(token::Brace)) {
6917 foreign_items.push(self.parse_foreign_item()?);
6920 let prev_span = self.prev_span;
6921 let m = ast::ForeignMod {
6923 items: foreign_items
6925 let invalid = keywords::Invalid.ident();
6926 Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
6929 /// Parse `type Foo = Bar;`
6931 /// `existential type Foo: Bar;`
6933 /// `return None` without modifying the parser state
6934 fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
6935 // This parses the grammar:
6936 // Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
6937 if self.check_keyword(keywords::Type) ||
6938 self.check_keyword(keywords::Existential) &&
6939 self.look_ahead(1, |t| t.is_keyword(keywords::Type)) {
6940 let existential = self.eat_keyword(keywords::Existential);
6941 assert!(self.eat_keyword(keywords::Type));
6942 Some(self.parse_existential_or_alias(existential))
6948 /// Parse type alias or existential type
6949 fn parse_existential_or_alias(
6952 ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
6953 let ident = self.parse_ident()?;
6954 let mut tps = self.parse_generics()?;
6955 tps.where_clause = self.parse_where_clause()?;
6956 let alias = if existential {
6957 self.expect(&token::Colon)?;
6958 let bounds = self.parse_generic_bounds()?;
6959 AliasKind::Existential(bounds)
6961 self.expect(&token::Eq)?;
6962 let ty = self.parse_ty()?;
6965 self.expect(&token::Semi)?;
6966 Ok((ident, alias, tps))
6969 /// Parse the part of an "enum" decl following the '{'
6970 fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
6971 let mut variants = Vec::new();
6972 let mut all_nullary = true;
6973 let mut any_disr = None;
6974 while self.token != token::CloseDelim(token::Brace) {
6975 let variant_attrs = self.parse_outer_attributes()?;
6976 let vlo = self.span;
6979 let mut disr_expr = None;
6980 let ident = self.parse_ident()?;
6981 if self.check(&token::OpenDelim(token::Brace)) {
6982 // Parse a struct variant.
6983 all_nullary = false;
6984 struct_def = VariantData::Struct(self.parse_record_struct_body()?,
6985 ast::DUMMY_NODE_ID);
6986 } else if self.check(&token::OpenDelim(token::Paren)) {
6987 all_nullary = false;
6988 struct_def = VariantData::Tuple(self.parse_tuple_struct_body()?,
6989 ast::DUMMY_NODE_ID);
6990 } else if self.eat(&token::Eq) {
6991 disr_expr = Some(AnonConst {
6992 id: ast::DUMMY_NODE_ID,
6993 value: self.parse_expr()?,
6995 any_disr = disr_expr.as_ref().map(|c| c.value.span);
6996 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6998 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
7001 let vr = ast::Variant_ {
7003 attrs: variant_attrs,
7007 variants.push(respan(vlo.to(self.prev_span), vr));
7009 if !self.eat(&token::Comma) { break; }
7011 self.expect(&token::CloseDelim(token::Brace))?;
7013 Some(disr_span) if !all_nullary =>
7014 self.span_err(disr_span,
7015 "discriminator values can only be used with a field-less enum"),
7019 Ok(ast::EnumDef { variants })
7022 /// Parse an "enum" declaration
7023 fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
7024 let id = self.parse_ident()?;
7025 let mut generics = self.parse_generics()?;
7026 generics.where_clause = self.parse_where_clause()?;
7027 self.expect(&token::OpenDelim(token::Brace))?;
7029 let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
7030 self.recover_stmt();
7031 self.eat(&token::CloseDelim(token::Brace));
7034 Ok((id, ItemKind::Enum(enum_definition, generics), None))
7037 /// Parses a string as an ABI spec on an extern type or module. Consumes
7038 /// the `extern` keyword, if one is found.
7039 fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
7041 token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
7043 self.expect_no_suffix(sp, "ABI spec", suf);
7045 match abi::lookup(&s.as_str()) {
7046 Some(abi) => Ok(Some(abi)),
7048 let prev_span = self.prev_span;
7049 let mut err = struct_span_err!(
7050 self.sess.span_diagnostic,
7053 "invalid ABI: found `{}`",
7055 err.span_label(prev_span, "invalid ABI");
7056 err.help(&format!("valid ABIs: {}", abi::all_names().join(", ")));
7067 fn is_static_global(&mut self) -> bool {
7068 if self.check_keyword(keywords::Static) {
7069 // Check if this could be a closure
7070 !self.look_ahead(1, |token| {
7071 if token.is_keyword(keywords::Move) {
7075 token::BinOp(token::Or) | token::OrOr => true,
7086 attrs: Vec<Attribute>,
7087 macros_allowed: bool,
7088 attributes_allowed: bool,
7089 ) -> PResult<'a, Option<P<Item>>> {
7090 let (ret, tokens) = self.collect_tokens(|this| {
7091 this.parse_item_implementation(attrs, macros_allowed, attributes_allowed)
7094 // Once we've parsed an item and recorded the tokens we got while
7095 // parsing we may want to store `tokens` into the item we're about to
7096 // return. Note, though, that we specifically didn't capture tokens
7097 // related to outer attributes. The `tokens` field here may later be
7098 // used with procedural macros to convert this item back into a token
7099 // stream, but during expansion we may be removing attributes as we go
7102 // If we've got inner attributes then the `tokens` we've got above holds
7103 // these inner attributes. If an inner attribute is expanded we won't
7104 // actually remove it from the token stream, so we'll just keep yielding
7105 // it (bad!). To work around this case for now we just avoid recording
7106 // `tokens` if we detect any inner attributes. This should help keep
7107 // expansion correct, but we should fix this bug one day!
7110 if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
7111 i.tokens = Some(tokens);
7118 /// Parse one of the items allowed by the flags.
7119 fn parse_item_implementation(
7121 attrs: Vec<Attribute>,
7122 macros_allowed: bool,
7123 attributes_allowed: bool,
7124 ) -> PResult<'a, Option<P<Item>>> {
7125 maybe_whole!(self, NtItem, |item| {
7126 let mut item = item.into_inner();
7127 let mut attrs = attrs;
7128 mem::swap(&mut item.attrs, &mut attrs);
7129 item.attrs.extend(attrs);
7135 let visibility = self.parse_visibility(false)?;
7137 if self.eat_keyword(keywords::Use) {
7139 let item_ = ItemKind::Use(P(self.parse_use_tree()?));
7140 self.expect(&token::Semi)?;
7142 let span = lo.to(self.prev_span);
7143 let item = self.mk_item(span, keywords::Invalid.ident(), item_, visibility, attrs);
7144 return Ok(Some(item));
7147 if self.check_keyword(keywords::Extern) && self.is_extern_non_path() {
7148 self.bump(); // `extern`
7149 if self.eat_keyword(keywords::Crate) {
7150 return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
7153 let opt_abi = self.parse_opt_abi()?;
7155 if self.eat_keyword(keywords::Fn) {
7156 // EXTERN FUNCTION ITEM
7157 let fn_span = self.prev_span;
7158 let abi = opt_abi.unwrap_or(Abi::C);
7159 let (ident, item_, extra_attrs) =
7160 self.parse_item_fn(Unsafety::Normal,
7162 respan(fn_span, Constness::NotConst),
7164 let prev_span = self.prev_span;
7165 let item = self.mk_item(lo.to(prev_span),
7169 maybe_append(attrs, extra_attrs));
7170 return Ok(Some(item));
7171 } else if self.check(&token::OpenDelim(token::Brace)) {
7172 return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
7178 if self.is_static_global() {
7181 let m = if self.eat_keyword(keywords::Mut) {
7184 Mutability::Immutable
7186 let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
7187 let prev_span = self.prev_span;
7188 let item = self.mk_item(lo.to(prev_span),
7192 maybe_append(attrs, extra_attrs));
7193 return Ok(Some(item));
7195 if self.eat_keyword(keywords::Const) {
7196 let const_span = self.prev_span;
7197 if self.check_keyword(keywords::Fn)
7198 || (self.check_keyword(keywords::Unsafe)
7199 && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
7200 // CONST FUNCTION ITEM
7201 let unsafety = self.parse_unsafety();
7203 let (ident, item_, extra_attrs) =
7204 self.parse_item_fn(unsafety,
7206 respan(const_span, Constness::Const),
7208 let prev_span = self.prev_span;
7209 let item = self.mk_item(lo.to(prev_span),
7213 maybe_append(attrs, extra_attrs));
7214 return Ok(Some(item));
7218 if self.eat_keyword(keywords::Mut) {
7219 let prev_span = self.prev_span;
7220 self.diagnostic().struct_span_err(prev_span, "const globals cannot be mutable")
7221 .help("did you mean to declare a static?")
7224 let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
7225 let prev_span = self.prev_span;
7226 let item = self.mk_item(lo.to(prev_span),
7230 maybe_append(attrs, extra_attrs));
7231 return Ok(Some(item));
7234 // `unsafe async fn` or `async fn`
7236 self.check_keyword(keywords::Unsafe) &&
7237 self.look_ahead(1, |t| t.is_keyword(keywords::Async))
7239 self.check_keyword(keywords::Async) &&
7240 self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
7243 // ASYNC FUNCTION ITEM
7244 let unsafety = self.parse_unsafety();
7245 self.expect_keyword(keywords::Async)?;
7246 self.expect_keyword(keywords::Fn)?;
7247 let fn_span = self.prev_span;
7248 let (ident, item_, extra_attrs) =
7249 self.parse_item_fn(unsafety,
7251 closure_id: ast::DUMMY_NODE_ID,
7252 return_impl_trait_id: ast::DUMMY_NODE_ID,
7254 respan(fn_span, Constness::NotConst),
7256 let prev_span = self.prev_span;
7257 let item = self.mk_item(lo.to(prev_span),
7261 maybe_append(attrs, extra_attrs));
7262 return Ok(Some(item));
7264 if self.check_keyword(keywords::Unsafe) &&
7265 (self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) ||
7266 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)))
7268 // UNSAFE TRAIT ITEM
7269 self.bump(); // `unsafe`
7270 let is_auto = if self.eat_keyword(keywords::Trait) {
7273 self.expect_keyword(keywords::Auto)?;
7274 self.expect_keyword(keywords::Trait)?;
7277 let (ident, item_, extra_attrs) =
7278 self.parse_item_trait(is_auto, Unsafety::Unsafe)?;
7279 let prev_span = self.prev_span;
7280 let item = self.mk_item(lo.to(prev_span),
7284 maybe_append(attrs, extra_attrs));
7285 return Ok(Some(item));
7287 if self.check_keyword(keywords::Impl) ||
7288 self.check_keyword(keywords::Unsafe) &&
7289 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7290 self.check_keyword(keywords::Default) &&
7291 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7292 self.check_keyword(keywords::Default) &&
7293 self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) {
7295 let defaultness = self.parse_defaultness();
7296 let unsafety = self.parse_unsafety();
7297 self.expect_keyword(keywords::Impl)?;
7298 let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?;
7299 let span = lo.to(self.prev_span);
7300 return Ok(Some(self.mk_item(span, ident, item, visibility,
7301 maybe_append(attrs, extra_attrs))));
7303 if self.check_keyword(keywords::Fn) {
7306 let fn_span = self.prev_span;
7307 let (ident, item_, extra_attrs) =
7308 self.parse_item_fn(Unsafety::Normal,
7310 respan(fn_span, Constness::NotConst),
7312 let prev_span = self.prev_span;
7313 let item = self.mk_item(lo.to(prev_span),
7317 maybe_append(attrs, extra_attrs));
7318 return Ok(Some(item));
7320 if self.check_keyword(keywords::Unsafe)
7321 && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
7322 // UNSAFE FUNCTION ITEM
7323 self.bump(); // `unsafe`
7324 // `{` is also expected after `unsafe`, in case of error, include it in the diagnostic
7325 self.check(&token::OpenDelim(token::Brace));
7326 let abi = if self.eat_keyword(keywords::Extern) {
7327 self.parse_opt_abi()?.unwrap_or(Abi::C)
7331 self.expect_keyword(keywords::Fn)?;
7332 let fn_span = self.prev_span;
7333 let (ident, item_, extra_attrs) =
7334 self.parse_item_fn(Unsafety::Unsafe,
7336 respan(fn_span, Constness::NotConst),
7338 let prev_span = self.prev_span;
7339 let item = self.mk_item(lo.to(prev_span),
7343 maybe_append(attrs, extra_attrs));
7344 return Ok(Some(item));
7346 if self.eat_keyword(keywords::Mod) {
7348 let (ident, item_, extra_attrs) =
7349 self.parse_item_mod(&attrs[..])?;
7350 let prev_span = self.prev_span;
7351 let item = self.mk_item(lo.to(prev_span),
7355 maybe_append(attrs, extra_attrs));
7356 return Ok(Some(item));
7358 if let Some(type_) = self.eat_type() {
7359 let (ident, alias, generics) = type_?;
7361 let item_ = match alias {
7362 AliasKind::Weak(ty) => ItemKind::Ty(ty, generics),
7363 AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics),
7365 let prev_span = self.prev_span;
7366 let item = self.mk_item(lo.to(prev_span),
7371 return Ok(Some(item));
7373 if self.eat_keyword(keywords::Enum) {
7375 let (ident, item_, extra_attrs) = self.parse_item_enum()?;
7376 let prev_span = self.prev_span;
7377 let item = self.mk_item(lo.to(prev_span),
7381 maybe_append(attrs, extra_attrs));
7382 return Ok(Some(item));
7384 if self.check_keyword(keywords::Trait)
7385 || (self.check_keyword(keywords::Auto)
7386 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
7388 let is_auto = if self.eat_keyword(keywords::Trait) {
7391 self.expect_keyword(keywords::Auto)?;
7392 self.expect_keyword(keywords::Trait)?;
7396 let (ident, item_, extra_attrs) =
7397 self.parse_item_trait(is_auto, Unsafety::Normal)?;
7398 let prev_span = self.prev_span;
7399 let item = self.mk_item(lo.to(prev_span),
7403 maybe_append(attrs, extra_attrs));
7404 return Ok(Some(item));
7406 if self.eat_keyword(keywords::Struct) {
7408 let (ident, item_, extra_attrs) = self.parse_item_struct()?;
7409 let prev_span = self.prev_span;
7410 let item = self.mk_item(lo.to(prev_span),
7414 maybe_append(attrs, extra_attrs));
7415 return Ok(Some(item));
7417 if self.is_union_item() {
7420 let (ident, item_, extra_attrs) = self.parse_item_union()?;
7421 let prev_span = self.prev_span;
7422 let item = self.mk_item(lo.to(prev_span),
7426 maybe_append(attrs, extra_attrs));
7427 return Ok(Some(item));
7429 if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, lo)? {
7430 return Ok(Some(macro_def));
7433 // Verify whether we have encountered a struct or method definition where the user forgot to
7434 // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
7435 if visibility.node.is_pub() &&
7436 self.check_ident() &&
7437 self.look_ahead(1, |t| *t != token::Not)
7439 // Space between `pub` keyword and the identifier
7442 // ^^^ `sp` points here
7443 let sp = self.prev_span.between(self.span);
7444 let full_sp = self.prev_span.to(self.span);
7445 let ident_sp = self.span;
7446 if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
7447 // possible public struct definition where `struct` was forgotten
7448 let ident = self.parse_ident().unwrap();
7449 let msg = format!("add `struct` here to parse `{}` as a public struct",
7451 let mut err = self.diagnostic()
7452 .struct_span_err(sp, "missing `struct` for struct definition");
7453 err.span_suggestion_short_with_applicability(
7454 sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
7457 } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
7458 let ident = self.parse_ident().unwrap();
7460 let kw_name = if let Ok(Some(_)) = self.parse_self_arg() {
7465 self.consume_block(token::Paren);
7466 let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) {
7467 self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]);
7469 ("fn", kw_name, false)
7470 } else if self.check(&token::OpenDelim(token::Brace)) {
7472 ("fn", kw_name, false)
7473 } else if self.check(&token::Colon) {
7477 ("fn` or `struct", "function or struct", true)
7479 self.consume_block(token::Brace);
7481 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7482 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7484 let suggestion = format!("add `{}` here to parse `{}` as a public {}",
7488 err.span_suggestion_short_with_applicability(
7489 sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
7492 if let Ok(snippet) = self.sess.source_map().span_to_snippet(ident_sp) {
7493 err.span_suggestion_with_applicability(
7495 "if you meant to call a macro, try",
7496 format!("{}!", snippet),
7497 // this is the `ambiguous` conditional branch
7498 Applicability::MaybeIncorrect
7501 err.help("if you meant to call a macro, remove the `pub` \
7502 and add a trailing `!` after the identifier");
7506 } else if self.look_ahead(1, |t| *t == token::Lt) {
7507 let ident = self.parse_ident().unwrap();
7508 self.eat_to_tokens(&[&token::Gt]);
7510 let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) {
7511 if let Ok(Some(_)) = self.parse_self_arg() {
7512 ("fn", "method", false)
7514 ("fn", "function", false)
7516 } else if self.check(&token::OpenDelim(token::Brace)) {
7517 ("struct", "struct", false)
7519 ("fn` or `struct", "function or struct", true)
7521 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7522 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7524 err.span_suggestion_short_with_applicability(
7526 &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name),
7527 format!(" {} ", kw),
7528 Applicability::MachineApplicable,
7534 self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, visibility)
7537 /// Parse a foreign item.
7538 crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> {
7539 maybe_whole!(self, NtForeignItem, |ni| ni);
7541 let attrs = self.parse_outer_attributes()?;
7543 let visibility = self.parse_visibility(false)?;
7545 // FOREIGN STATIC ITEM
7546 // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
7547 if self.check_keyword(keywords::Static) || self.token.is_keyword(keywords::Const) {
7548 if self.token.is_keyword(keywords::Const) {
7550 .struct_span_err(self.span, "extern items cannot be `const`")
7551 .span_suggestion_with_applicability(
7553 "try using a static value",
7554 "static".to_owned(),
7555 Applicability::MachineApplicable
7558 self.bump(); // `static` or `const`
7559 return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
7561 // FOREIGN FUNCTION ITEM
7562 if self.check_keyword(keywords::Fn) {
7563 return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?);
7565 // FOREIGN TYPE ITEM
7566 if self.check_keyword(keywords::Type) {
7567 return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
7570 match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
7574 ident: keywords::Invalid.ident(),
7575 span: lo.to(self.prev_span),
7576 id: ast::DUMMY_NODE_ID,
7579 node: ForeignItemKind::Macro(mac),
7584 if !attrs.is_empty() {
7585 self.expected_item_err(&attrs);
7593 /// This is the fall-through for parsing items.
7594 fn parse_macro_use_or_failure(
7596 attrs: Vec<Attribute> ,
7597 macros_allowed: bool,
7598 attributes_allowed: bool,
7600 visibility: Visibility
7601 ) -> PResult<'a, Option<P<Item>>> {
7602 if macros_allowed && self.token.is_path_start() {
7603 // MACRO INVOCATION ITEM
7605 let prev_span = self.prev_span;
7606 self.complain_if_pub_macro(&visibility.node, prev_span);
7608 let mac_lo = self.span;
7611 let pth = self.parse_path(PathStyle::Mod)?;
7612 self.expect(&token::Not)?;
7614 // a 'special' identifier (like what `macro_rules!` uses)
7615 // is optional. We should eventually unify invoc syntax
7617 let id = if self.token.is_ident() {
7620 keywords::Invalid.ident() // no special identifier
7622 // eat a matched-delimiter token tree:
7623 let (delim, tts) = self.expect_delimited_token_tree()?;
7624 if delim != MacDelimiter::Brace {
7625 if !self.eat(&token::Semi) {
7626 self.span_err(self.prev_span,
7627 "macros that expand to items must either \
7628 be surrounded with braces or followed by \
7633 let hi = self.prev_span;
7634 let mac = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim });
7635 let item = self.mk_item(lo.to(hi), id, ItemKind::Mac(mac), visibility, attrs);
7636 return Ok(Some(item));
7639 // FAILURE TO PARSE ITEM
7640 match visibility.node {
7641 VisibilityKind::Inherited => {}
7643 return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
7647 if !attributes_allowed && !attrs.is_empty() {
7648 self.expected_item_err(&attrs);
7653 /// Parse a macro invocation inside a `trait`, `impl` or `extern` block
7654 fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
7655 at_end: &mut bool) -> PResult<'a, Option<Mac>>
7657 if self.token.is_path_start() && !self.is_extern_non_path() {
7658 let prev_span = self.prev_span;
7660 let pth = self.parse_path(PathStyle::Mod)?;
7662 if pth.segments.len() == 1 {
7663 if !self.eat(&token::Not) {
7664 return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
7667 self.expect(&token::Not)?;
7670 if let Some(vis) = vis {
7671 self.complain_if_pub_macro(&vis.node, prev_span);
7676 // eat a matched-delimiter token tree:
7677 let (delim, tts) = self.expect_delimited_token_tree()?;
7678 if delim != MacDelimiter::Brace {
7679 self.expect(&token::Semi)?
7682 Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim })))
7688 fn collect_tokens<F, R>(&mut self, f: F) -> PResult<'a, (R, TokenStream)>
7689 where F: FnOnce(&mut Self) -> PResult<'a, R>
7691 // Record all tokens we parse when parsing this item.
7692 let mut tokens = Vec::new();
7693 let prev_collecting = match self.token_cursor.frame.last_token {
7694 LastToken::Collecting(ref mut list) => {
7695 Some(mem::replace(list, Vec::new()))
7697 LastToken::Was(ref mut last) => {
7698 tokens.extend(last.take());
7702 self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
7703 let prev = self.token_cursor.stack.len();
7705 let last_token = if self.token_cursor.stack.len() == prev {
7706 &mut self.token_cursor.frame.last_token
7708 &mut self.token_cursor.stack[prev].last_token
7711 // Pull our the toekns that we've collected from the call to `f` above
7712 let mut collected_tokens = match *last_token {
7713 LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()),
7714 LastToken::Was(_) => panic!("our vector went away?"),
7717 // If we're not at EOF our current token wasn't actually consumed by
7718 // `f`, but it'll still be in our list that we pulled out. In that case
7720 let extra_token = if self.token != token::Eof {
7721 collected_tokens.pop()
7726 // If we were previously collecting tokens, then this was a recursive
7727 // call. In that case we need to record all the tokens we collected in
7728 // our parent list as well. To do that we push a clone of our stream
7729 // onto the previous list.
7730 let stream = collected_tokens.into_iter().collect::<TokenStream>();
7731 match prev_collecting {
7733 list.push(stream.clone());
7734 list.extend(extra_token);
7735 *last_token = LastToken::Collecting(list);
7738 *last_token = LastToken::Was(extra_token);
7745 pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
7746 let attrs = self.parse_outer_attributes()?;
7747 self.parse_item_(attrs, true, false)
7751 fn is_import_coupler(&mut self) -> bool {
7752 self.check(&token::ModSep) &&
7753 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
7754 *t == token::BinOp(token::Star))
7759 /// USE_TREE = [`::`] `*` |
7760 /// [`::`] `{` USE_TREE_LIST `}` |
7762 /// PATH `::` `{` USE_TREE_LIST `}` |
7763 /// PATH [`as` IDENT]
7764 fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
7767 let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
7768 let kind = if self.check(&token::OpenDelim(token::Brace)) ||
7769 self.check(&token::BinOp(token::Star)) ||
7770 self.is_import_coupler() {
7771 // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
7772 let mod_sep_ctxt = self.span.ctxt();
7773 if self.eat(&token::ModSep) {
7774 prefix.segments.push(
7775 PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
7779 if self.eat(&token::BinOp(token::Star)) {
7782 UseTreeKind::Nested(self.parse_use_tree_list()?)
7785 // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
7786 prefix = self.parse_path(PathStyle::Mod)?;
7788 if self.eat(&token::ModSep) {
7789 if self.eat(&token::BinOp(token::Star)) {
7792 UseTreeKind::Nested(self.parse_use_tree_list()?)
7795 UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID)
7799 Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
7802 /// Parse UseTreeKind::Nested(list)
7804 /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
7805 fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
7806 self.parse_unspanned_seq(&token::OpenDelim(token::Brace),
7807 &token::CloseDelim(token::Brace),
7808 SeqSep::trailing_allowed(token::Comma), |this| {
7809 Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID))
7813 fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
7814 if self.eat_keyword(keywords::As) {
7815 self.parse_ident_or_underscore().map(Some)
7821 /// Parses a source module as a crate. This is the main
7822 /// entry point for the parser.
7823 pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
7826 attrs: self.parse_inner_attributes()?,
7827 module: self.parse_mod_items(&token::Eof, lo)?,
7828 span: lo.to(self.span),
7832 pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
7833 let ret = match self.token {
7834 token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf),
7835 token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf),
7842 pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
7843 match self.parse_optional_str() {
7844 Some((s, style, suf)) => {
7845 let sp = self.prev_span;
7846 self.expect_no_suffix(sp, "string literal", suf);
7850 let msg = "expected string literal";
7851 let mut err = self.fatal(msg);
7852 err.span_label(self.span, msg);