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 (true, token::Ident(ref s, false), true) = (
802 self.span.rust_2018(),
804 self.token.is_used_keyword() || self.token.is_unused_keyword(),
806 err.span_suggestion_with_applicability(
808 "you can escape reserved keywords to use them as identifiers",
809 format!("r#{}", s.to_string()),
810 Applicability::MaybeIncorrect,
812 } else if let Some(token_descr) = self.token_descr() {
813 err.span_label(self.span, format!("expected identifier, found {}", token_descr));
815 err.span_label(self.span, "expected identifier");
816 if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) {
817 err.span_suggestion_with_applicability(
821 Applicability::MachineApplicable,
828 pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
829 self.parse_ident_common(true)
832 fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
834 token::Ident(ident, _) => {
835 if self.token.is_reserved_ident() {
836 let mut err = self.expected_ident_found();
843 let span = self.span;
845 Ok(Ident::new(ident.name, span))
848 Err(if self.prev_token_kind == PrevTokenKind::DocComment {
849 self.span_fatal_err(self.prev_span, Error::UselessDocComment)
851 self.expected_ident_found()
857 /// Check if the next token is `tok`, and return `true` if so.
859 /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
861 crate fn check(&mut self, tok: &token::Token) -> bool {
862 let is_present = self.token == *tok;
863 if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
867 /// Consume token 'tok' if it exists. Returns true if the given
868 /// token was present, false otherwise.
869 pub fn eat(&mut self, tok: &token::Token) -> bool {
870 let is_present = self.check(tok);
871 if is_present { self.bump() }
875 fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
876 self.expected_tokens.push(TokenType::Keyword(kw));
877 self.token.is_keyword(kw)
880 /// If the next token is the given keyword, eat it and return
881 /// true. Otherwise, return false.
882 pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
883 if self.check_keyword(kw) {
891 fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
892 if self.token.is_keyword(kw) {
900 /// If the given word is not a keyword, signal an error.
901 /// If the next token is not the given word, signal an error.
902 /// Otherwise, eat it.
903 fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> {
904 if !self.eat_keyword(kw) {
911 fn check_ident(&mut self) -> bool {
912 if self.token.is_ident() {
915 self.expected_tokens.push(TokenType::Ident);
920 fn check_path(&mut self) -> bool {
921 if self.token.is_path_start() {
924 self.expected_tokens.push(TokenType::Path);
929 fn check_type(&mut self) -> bool {
930 if self.token.can_begin_type() {
933 self.expected_tokens.push(TokenType::Type);
938 /// Expect and consume a `+`. if `+=` is seen, replace it with a `=`
939 /// and continue. If a `+` is not seen, return false.
941 /// This is using when token splitting += into +.
942 /// See issue 47856 for an example of when this may occur.
943 fn eat_plus(&mut self) -> bool {
944 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
946 token::BinOp(token::Plus) => {
950 token::BinOpEq(token::Plus) => {
951 let span = self.span.with_lo(self.span.lo() + BytePos(1));
952 self.bump_with(token::Eq, span);
960 /// Checks to see if the next token is either `+` or `+=`.
961 /// Otherwise returns false.
962 fn check_plus(&mut self) -> bool {
963 if self.token.is_like_plus() {
967 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
972 /// Expect and consume an `&`. If `&&` is seen, replace it with a single
973 /// `&` and continue. If an `&` is not seen, signal an error.
974 fn expect_and(&mut self) -> PResult<'a, ()> {
975 self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
977 token::BinOp(token::And) => {
982 let span = self.span.with_lo(self.span.lo() + BytePos(1));
983 Ok(self.bump_with(token::BinOp(token::And), span))
985 _ => self.unexpected()
989 /// Expect and consume an `|`. If `||` is seen, replace it with a single
990 /// `|` and continue. If an `|` is not seen, signal an error.
991 fn expect_or(&mut self) -> PResult<'a, ()> {
992 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or)));
994 token::BinOp(token::Or) => {
999 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1000 Ok(self.bump_with(token::BinOp(token::Or), span))
1002 _ => self.unexpected()
1006 fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
1008 None => {/* everything ok */}
1010 let text = suf.as_str();
1011 if text.is_empty() {
1012 self.span_bug(sp, "found empty literal suffix in Some")
1014 self.span_err(sp, &format!("{} with a suffix is invalid", kind));
1019 /// Attempt to consume a `<`. If `<<` is seen, replace it with a single
1020 /// `<` and continue. If a `<` is not seen, return false.
1022 /// This is meant to be used when parsing generics on a path to get the
1024 fn eat_lt(&mut self) -> bool {
1025 self.expected_tokens.push(TokenType::Token(token::Lt));
1031 token::BinOp(token::Shl) => {
1032 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1033 self.bump_with(token::Lt, span);
1040 fn expect_lt(&mut self) -> PResult<'a, ()> {
1048 /// Expect and consume a GT. if a >> is seen, replace it
1049 /// with a single > and continue. If a GT is not seen,
1050 /// signal an error.
1051 fn expect_gt(&mut self) -> PResult<'a, ()> {
1052 self.expected_tokens.push(TokenType::Token(token::Gt));
1058 token::BinOp(token::Shr) => {
1059 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1060 Ok(self.bump_with(token::Gt, span))
1062 token::BinOpEq(token::Shr) => {
1063 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1064 Ok(self.bump_with(token::Ge, span))
1067 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1068 Ok(self.bump_with(token::Eq, span))
1070 _ => self.unexpected()
1074 /// Eat and discard tokens until one of `kets` is encountered. Respects token trees,
1075 /// passes through any errors encountered. Used for error recovery.
1076 fn eat_to_tokens(&mut self, kets: &[&token::Token]) {
1077 let handler = self.diagnostic();
1079 if let Err(ref mut err) = self.parse_seq_to_before_tokens(kets,
1081 TokenExpectType::Expect,
1082 |p| Ok(p.parse_token_tree())) {
1083 handler.cancel(err);
1087 /// Parse a sequence, including the closing delimiter. The function
1088 /// f must consume tokens until reaching the next separator or
1089 /// closing bracket.
1090 pub fn parse_seq_to_end<T, F>(&mut self,
1094 -> PResult<'a, Vec<T>> where
1095 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1097 let val = self.parse_seq_to_before_end(ket, sep, f)?;
1102 /// Parse a sequence, not including the closing delimiter. The function
1103 /// f must consume tokens until reaching the next separator or
1104 /// closing bracket.
1105 pub fn parse_seq_to_before_end<T, F>(&mut self,
1109 -> PResult<'a, Vec<T>>
1110 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1112 self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
1115 fn parse_seq_to_before_tokens<T, F>(
1117 kets: &[&token::Token],
1119 expect: TokenExpectType,
1121 ) -> PResult<'a, Vec<T>>
1122 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1124 let mut first: bool = true;
1126 while !kets.iter().any(|k| {
1128 TokenExpectType::Expect => self.check(k),
1129 TokenExpectType::NoExpect => self.token == **k,
1133 token::CloseDelim(..) | token::Eof => break,
1136 if let Some(ref t) = sep.sep {
1140 if let Err(mut e) = self.expect(t) {
1141 // Attempt to keep parsing if it was a similar separator
1142 if let Some(ref tokens) = t.similar_tokens() {
1143 if tokens.contains(&self.token) {
1148 // Attempt to keep parsing if it was an omitted separator
1162 if sep.trailing_sep_allowed && kets.iter().any(|k| {
1164 TokenExpectType::Expect => self.check(k),
1165 TokenExpectType::NoExpect => self.token == **k,
1178 /// Parse a sequence, including the closing delimiter. The function
1179 /// f must consume tokens until reaching the next separator or
1180 /// closing bracket.
1181 fn parse_unspanned_seq<T, F>(&mut self,
1186 -> PResult<'a, Vec<T>> where
1187 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1190 let result = self.parse_seq_to_before_end(ket, sep, f)?;
1195 /// Advance the parser by one token
1196 pub fn bump(&mut self) {
1197 if self.prev_token_kind == PrevTokenKind::Eof {
1198 // Bumping after EOF is a bad sign, usually an infinite loop.
1199 self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
1202 self.prev_span = self.meta_var_span.take().unwrap_or(self.span);
1204 // Record last token kind for possible error recovery.
1205 self.prev_token_kind = match self.token {
1206 token::DocComment(..) => PrevTokenKind::DocComment,
1207 token::Comma => PrevTokenKind::Comma,
1208 token::BinOp(token::Plus) => PrevTokenKind::Plus,
1209 token::Interpolated(..) => PrevTokenKind::Interpolated,
1210 token::Eof => PrevTokenKind::Eof,
1211 token::Ident(..) => PrevTokenKind::Ident,
1212 _ => PrevTokenKind::Other,
1215 let next = self.next_tok();
1216 self.span = next.sp;
1217 self.token = next.tok;
1218 self.expected_tokens.clear();
1219 // check after each token
1220 self.process_potential_macro_variable();
1223 /// Advance the parser using provided token as a next one. Use this when
1224 /// consuming a part of a token. For example a single `<` from `<<`.
1225 fn bump_with(&mut self, next: token::Token, span: Span) {
1226 self.prev_span = self.span.with_hi(span.lo());
1227 // It would be incorrect to record the kind of the current token, but
1228 // fortunately for tokens currently using `bump_with`, the
1229 // prev_token_kind will be of no use anyway.
1230 self.prev_token_kind = PrevTokenKind::Other;
1233 self.expected_tokens.clear();
1236 pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where
1237 F: FnOnce(&token::Token) -> R,
1240 return f(&self.token)
1243 f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1244 Some(tree) => match tree {
1245 TokenTree::Token(_, tok) => tok,
1246 TokenTree::Delimited(_, delim, _) => token::OpenDelim(delim),
1248 None => token::CloseDelim(self.token_cursor.frame.delim),
1252 fn look_ahead_span(&self, dist: usize) -> Span {
1257 match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1258 Some(TokenTree::Token(span, _)) => span,
1259 Some(TokenTree::Delimited(span, ..)) => span.entire(),
1260 None => self.look_ahead_span(dist - 1),
1263 pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
1264 self.sess.span_diagnostic.struct_span_fatal(self.span, m)
1266 pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1267 self.sess.span_diagnostic.struct_span_fatal(sp, m)
1269 fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> {
1270 err.span_err(sp, self.diagnostic())
1272 fn bug(&self, m: &str) -> ! {
1273 self.sess.span_diagnostic.span_bug(self.span, m)
1275 fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
1276 self.sess.span_diagnostic.span_err(sp, m)
1278 fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1279 self.sess.span_diagnostic.struct_span_err(sp, m)
1281 crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
1282 self.sess.span_diagnostic.span_bug(sp, m)
1284 crate fn abort_if_errors(&self) {
1285 self.sess.span_diagnostic.abort_if_errors();
1288 fn cancel(&self, err: &mut DiagnosticBuilder) {
1289 self.sess.span_diagnostic.cancel(err)
1292 crate fn diagnostic(&self) -> &'a errors::Handler {
1293 &self.sess.span_diagnostic
1296 /// Is the current token one of the keywords that signals a bare function
1298 fn token_is_bare_fn_keyword(&mut self) -> bool {
1299 self.check_keyword(keywords::Fn) ||
1300 self.check_keyword(keywords::Unsafe) ||
1301 self.check_keyword(keywords::Extern) && self.is_extern_non_path()
1304 /// parse a `TyKind::BareFn` type:
1305 fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
1308 [unsafe] [extern "ABI"] fn (S) -> T
1318 let unsafety = self.parse_unsafety();
1319 let abi = if self.eat_keyword(keywords::Extern) {
1320 self.parse_opt_abi()?.unwrap_or(Abi::C)
1325 self.expect_keyword(keywords::Fn)?;
1326 let (inputs, variadic) = self.parse_fn_args(false, true)?;
1327 let ret_ty = self.parse_ret_ty(false)?;
1328 let decl = P(FnDecl {
1333 Ok(TyKind::BareFn(P(BareFnTy {
1341 /// Parse asyncness: `async` or nothing
1342 fn parse_asyncness(&mut self) -> IsAsync {
1343 if self.eat_keyword(keywords::Async) {
1345 closure_id: ast::DUMMY_NODE_ID,
1346 return_impl_trait_id: ast::DUMMY_NODE_ID,
1353 /// Parse unsafety: `unsafe` or nothing.
1354 fn parse_unsafety(&mut self) -> Unsafety {
1355 if self.eat_keyword(keywords::Unsafe) {
1362 /// Parse the items in a trait declaration
1363 pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> {
1364 maybe_whole!(self, NtTraitItem, |x| x);
1365 let attrs = self.parse_outer_attributes()?;
1366 let (mut item, tokens) = self.collect_tokens(|this| {
1367 this.parse_trait_item_(at_end, attrs)
1369 // See `parse_item` for why this clause is here.
1370 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
1371 item.tokens = Some(tokens);
1376 fn parse_trait_item_(&mut self,
1378 mut attrs: Vec<Attribute>) -> PResult<'a, TraitItem> {
1381 let (name, node, generics) = if self.eat_keyword(keywords::Type) {
1382 self.parse_trait_item_assoc_ty()?
1383 } else if self.is_const_item() {
1384 self.expect_keyword(keywords::Const)?;
1385 let ident = self.parse_ident()?;
1386 self.expect(&token::Colon)?;
1387 let ty = self.parse_ty()?;
1388 let default = if self.eat(&token::Eq) {
1389 let expr = self.parse_expr()?;
1390 self.expect(&token::Semi)?;
1393 self.expect(&token::Semi)?;
1396 (ident, TraitItemKind::Const(ty, default), ast::Generics::default())
1397 } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
1398 // trait item macro.
1399 (keywords::Invalid.ident(), ast::TraitItemKind::Macro(mac), ast::Generics::default())
1401 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
1403 let ident = self.parse_ident()?;
1404 let mut generics = self.parse_generics()?;
1406 let d = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
1407 // This is somewhat dubious; We don't want to allow
1408 // argument names to be left off if there is a
1411 // We don't allow argument names to be left off in edition 2018.
1412 p.parse_arg_general(p.span.rust_2018(), true)
1414 generics.where_clause = self.parse_where_clause()?;
1416 let sig = ast::MethodSig {
1426 let body = match self.token {
1430 debug!("parse_trait_methods(): parsing required method");
1433 token::OpenDelim(token::Brace) => {
1434 debug!("parse_trait_methods(): parsing provided method");
1436 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1437 attrs.extend(inner_attrs.iter().cloned());
1440 token::Interpolated(ref nt) => {
1442 token::NtBlock(..) => {
1444 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1445 attrs.extend(inner_attrs.iter().cloned());
1449 let token_str = self.this_token_descr();
1450 let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
1452 err.span_label(self.span, "expected `;` or `{`");
1458 let token_str = self.this_token_descr();
1459 let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
1461 err.span_label(self.span, "expected `;` or `{`");
1465 (ident, ast::TraitItemKind::Method(sig, body), generics)
1469 id: ast::DUMMY_NODE_ID,
1474 span: lo.to(self.prev_span),
1479 /// Parse optional return type [ -> TY ] in function decl
1480 fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> {
1481 if self.eat(&token::RArrow) {
1482 Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true)?))
1484 Ok(FunctionRetTy::Default(self.span.shrink_to_lo()))
1489 pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
1490 self.parse_ty_common(true, true)
1493 /// Parse a type in restricted contexts where `+` is not permitted.
1494 /// Example 1: `&'a TYPE`
1495 /// `+` is prohibited to maintain operator priority (P(+) < P(&)).
1496 /// Example 2: `value1 as TYPE + value2`
1497 /// `+` is prohibited to avoid interactions with expression grammar.
1498 fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
1499 self.parse_ty_common(false, true)
1502 fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool)
1503 -> PResult<'a, P<Ty>> {
1504 maybe_whole!(self, NtTy, |x| x);
1507 let mut impl_dyn_multi = false;
1508 let node = if self.eat(&token::OpenDelim(token::Paren)) {
1509 // `(TYPE)` is a parenthesized type.
1510 // `(TYPE,)` is a tuple with a single field of type TYPE.
1511 let mut ts = vec![];
1512 let mut last_comma = false;
1513 while self.token != token::CloseDelim(token::Paren) {
1514 ts.push(self.parse_ty()?);
1515 if self.eat(&token::Comma) {
1522 let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
1523 self.expect(&token::CloseDelim(token::Paren))?;
1525 if ts.len() == 1 && !last_comma {
1526 let ty = ts.into_iter().nth(0).unwrap().into_inner();
1527 let maybe_bounds = allow_plus && self.token.is_like_plus();
1529 // `(TY_BOUND_NOPAREN) + BOUND + ...`.
1530 TyKind::Path(None, ref path) if maybe_bounds => {
1531 self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
1533 TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
1534 if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
1535 let path = match bounds[0] {
1536 GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
1537 GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
1539 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1542 _ => TyKind::Paren(P(ty))
1547 } else if self.eat(&token::Not) {
1550 } else if self.eat(&token::BinOp(token::Star)) {
1552 TyKind::Ptr(self.parse_ptr()?)
1553 } else if self.eat(&token::OpenDelim(token::Bracket)) {
1555 let t = self.parse_ty()?;
1556 // Parse optional `; EXPR` in `[TYPE; EXPR]`
1557 let t = match self.maybe_parse_fixed_length_of_vec()? {
1558 None => TyKind::Slice(t),
1559 Some(length) => TyKind::Array(t, AnonConst {
1560 id: ast::DUMMY_NODE_ID,
1564 self.expect(&token::CloseDelim(token::Bracket))?;
1566 } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
1569 self.parse_borrowed_pointee()?
1570 } else if self.eat_keyword_noexpect(keywords::Typeof) {
1572 // In order to not be ambiguous, the type must be surrounded by parens.
1573 self.expect(&token::OpenDelim(token::Paren))?;
1575 id: ast::DUMMY_NODE_ID,
1576 value: self.parse_expr()?,
1578 self.expect(&token::CloseDelim(token::Paren))?;
1580 } else if self.eat_keyword(keywords::Underscore) {
1581 // A type to be inferred `_`
1583 } else if self.token_is_bare_fn_keyword() {
1584 // Function pointer type
1585 self.parse_ty_bare_fn(Vec::new())?
1586 } else if self.check_keyword(keywords::For) {
1587 // Function pointer type or bound list (trait object type) starting with a poly-trait.
1588 // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
1589 // `for<'lt> Trait1<'lt> + Trait2 + 'a`
1591 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
1592 if self.token_is_bare_fn_keyword() {
1593 self.parse_ty_bare_fn(lifetime_defs)?
1595 let path = self.parse_path(PathStyle::Type)?;
1596 let parse_plus = allow_plus && self.check_plus();
1597 self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
1599 } else if self.eat_keyword(keywords::Impl) {
1600 // Always parse bounds greedily for better error recovery.
1601 let bounds = self.parse_generic_bounds()?;
1602 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1603 TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
1604 } else if self.check_keyword(keywords::Dyn) &&
1605 (self.span.rust_2018() ||
1606 self.look_ahead(1, |t| t.can_begin_bound() &&
1607 !can_continue_type_after_non_fn_ident(t))) {
1608 self.bump(); // `dyn`
1609 // Always parse bounds greedily for better error recovery.
1610 let bounds = self.parse_generic_bounds()?;
1611 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1612 TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
1613 } else if self.check(&token::Question) ||
1614 self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
1615 // Bound list (trait object type)
1616 TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus)?,
1617 TraitObjectSyntax::None)
1618 } else if self.eat_lt() {
1620 let (qself, path) = self.parse_qpath(PathStyle::Type)?;
1621 TyKind::Path(Some(qself), path)
1622 } else if self.token.is_path_start() {
1624 let path = self.parse_path(PathStyle::Type)?;
1625 if self.eat(&token::Not) {
1626 // Macro invocation in type position
1627 let (delim, tts) = self.expect_delimited_token_tree()?;
1628 let node = Mac_ { path, tts, delim };
1629 TyKind::Mac(respan(lo.to(self.prev_span), node))
1631 // Just a type path or bound list (trait object type) starting with a trait.
1633 // `Trait1 + Trait2 + 'a`
1634 if allow_plus && self.check_plus() {
1635 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1637 TyKind::Path(None, path)
1641 let msg = format!("expected type, found {}", self.this_token_descr());
1642 return Err(self.fatal(&msg));
1645 let span = lo.to(self.prev_span);
1646 let ty = Ty { node, span, id: ast::DUMMY_NODE_ID };
1648 // Try to recover from use of `+` with incorrect priority.
1649 self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
1650 self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
1651 let ty = self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)?;
1656 fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
1657 lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
1658 let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));
1659 let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
1661 self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
1662 bounds.append(&mut self.parse_generic_bounds()?);
1664 Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
1667 fn maybe_report_ambiguous_plus(&mut self, allow_plus: bool, impl_dyn_multi: bool, ty: &Ty) {
1668 if !allow_plus && impl_dyn_multi {
1669 let sum_with_parens = format!("({})", pprust::ty_to_string(&ty));
1670 self.struct_span_err(ty.span, "ambiguous `+` in a type")
1671 .span_suggestion_with_applicability(
1673 "use parentheses to disambiguate",
1675 Applicability::MachineApplicable
1680 fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> {
1681 // Do not add `+` to expected tokens.
1682 if !allow_plus || !self.token.is_like_plus() {
1687 let bounds = self.parse_generic_bounds()?;
1688 let sum_span = ty.span.to(self.prev_span);
1690 let mut err = struct_span_err!(self.sess.span_diagnostic, sum_span, E0178,
1691 "expected a path on the left-hand side of `+`, not `{}`", pprust::ty_to_string(ty));
1694 TyKind::Rptr(ref lifetime, ref mut_ty) => {
1695 let sum_with_parens = pprust::to_string(|s| {
1696 use print::pprust::PrintState;
1699 s.print_opt_lifetime(lifetime)?;
1700 s.print_mutability(mut_ty.mutbl)?;
1702 s.print_type(&mut_ty.ty)?;
1703 s.print_type_bounds(" +", &bounds)?;
1706 err.span_suggestion_with_applicability(
1708 "try adding parentheses",
1710 Applicability::MachineApplicable
1713 TyKind::Ptr(..) | TyKind::BareFn(..) => {
1714 err.span_label(sum_span, "perhaps you forgot parentheses?");
1717 err.span_label(sum_span, "expected a path");
1724 // Try to recover from associated item paths like `[T]::AssocItem`/`(T, U)::AssocItem`.
1725 fn maybe_recover_from_bad_qpath<T: RecoverQPath>(&mut self, base: T, allow_recovery: bool)
1727 // Do not add `::` to expected tokens.
1728 if !allow_recovery || self.token != token::ModSep {
1731 let ty = match base.to_ty() {
1733 None => return Ok(base),
1736 self.bump(); // `::`
1737 let mut segments = Vec::new();
1738 self.parse_path_segments(&mut segments, T::PATH_STYLE, true)?;
1740 let span = ty.span.to(self.prev_span);
1741 let path_span = span.to(span); // use an empty path since `position` == 0
1742 let recovered = base.to_recovered(
1743 Some(QSelf { ty, path_span, position: 0 }),
1744 ast::Path { segments, span },
1748 .struct_span_err(span, "missing angle brackets in associated item path")
1749 .span_suggestion_with_applicability( // this is a best-effort recovery
1750 span, "try", recovered.to_string(), Applicability::MaybeIncorrect
1756 fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
1757 let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
1758 let mutbl = self.parse_mutability();
1759 let ty = self.parse_ty_no_plus()?;
1760 return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl }));
1763 fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
1764 let mutbl = if self.eat_keyword(keywords::Mut) {
1766 } else if self.eat_keyword(keywords::Const) {
1767 Mutability::Immutable
1769 let span = self.prev_span;
1771 "expected mut or const in raw pointer type (use \
1772 `*mut T` or `*const T` as appropriate)");
1773 Mutability::Immutable
1775 let t = self.parse_ty_no_plus()?;
1776 Ok(MutTy { ty: t, mutbl: mutbl })
1779 fn is_named_argument(&mut self) -> bool {
1780 let offset = match self.token {
1781 token::Interpolated(ref nt) => match nt.0 {
1782 token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
1785 token::BinOp(token::And) | token::AndAnd => 1,
1786 _ if self.token.is_keyword(keywords::Mut) => 1,
1790 self.look_ahead(offset, |t| t.is_ident()) &&
1791 self.look_ahead(offset + 1, |t| t == &token::Colon)
1794 /// Skip unexpected attributes and doc comments in this position and emit an appropriate error.
1795 fn eat_incorrect_doc_comment(&mut self, applied_to: &str) {
1796 if let token::DocComment(_) = self.token {
1797 let mut err = self.diagnostic().struct_span_err(
1799 &format!("documentation comments cannot be applied to {}", applied_to),
1801 err.span_label(self.span, "doc comments are not allowed here");
1804 } else if self.token == token::Pound && self.look_ahead(1, |t| {
1805 *t == token::OpenDelim(token::Bracket)
1808 // Skip every token until next possible arg.
1809 while self.token != token::CloseDelim(token::Bracket) {
1812 let sp = lo.to(self.span);
1814 let mut err = self.diagnostic().struct_span_err(
1816 &format!("attributes cannot be applied to {}", applied_to),
1818 err.span_label(sp, "attributes are not allowed here");
1823 /// This version of parse arg doesn't necessarily require
1824 /// identifier names.
1825 fn parse_arg_general(&mut self, require_name: bool, is_trait_item: bool) -> PResult<'a, Arg> {
1826 maybe_whole!(self, NtArg, |x| x);
1828 if let Ok(Some(_)) = self.parse_self_arg() {
1829 let mut err = self.struct_span_err(self.prev_span,
1830 "unexpected `self` argument in function");
1831 err.span_label(self.prev_span,
1832 "`self` is only valid as the first argument of an associated function");
1836 let (pat, ty) = if require_name || self.is_named_argument() {
1837 debug!("parse_arg_general parse_pat (require_name:{})",
1839 self.eat_incorrect_doc_comment("method arguments");
1840 let pat = self.parse_pat(Some("argument name"))?;
1842 if let Err(mut err) = self.expect(&token::Colon) {
1843 // If we find a pattern followed by an identifier, it could be an (incorrect)
1844 // C-style parameter declaration.
1845 if self.check_ident() && self.look_ahead(1, |t| {
1846 *t == token::Comma || *t == token::CloseDelim(token::Paren)
1848 let ident = self.parse_ident().unwrap();
1849 let span = pat.span.with_hi(ident.span.hi());
1851 err.span_suggestion_with_applicability(
1853 "declare the type after the parameter binding",
1854 String::from("<identifier>: <type>"),
1855 Applicability::HasPlaceholders,
1857 } else if require_name && is_trait_item {
1858 if let PatKind::Ident(_, ident, _) = pat.node {
1859 err.span_suggestion_with_applicability(
1861 "explicitly ignore parameter",
1862 format!("_: {}", ident),
1863 Applicability::MachineApplicable,
1867 err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
1873 self.eat_incorrect_doc_comment("a method argument's type");
1874 (pat, self.parse_ty()?)
1876 debug!("parse_arg_general ident_to_pat");
1877 let parser_snapshot_before_ty = self.clone();
1878 self.eat_incorrect_doc_comment("a method argument's type");
1879 let mut ty = self.parse_ty();
1880 if ty.is_ok() && self.token == token::Colon {
1881 // This wasn't actually a type, but a pattern looking like a type,
1882 // so we are going to rollback and re-parse for recovery.
1883 ty = self.unexpected();
1887 let ident = Ident::new(keywords::Invalid.name(), self.prev_span);
1889 id: ast::DUMMY_NODE_ID,
1890 node: PatKind::Ident(
1891 BindingMode::ByValue(Mutability::Immutable), ident, None),
1897 // Recover from attempting to parse the argument as a type without pattern.
1899 mem::replace(self, parser_snapshot_before_ty);
1900 let pat = self.parse_pat(Some("argument name"))?;
1901 self.expect(&token::Colon)?;
1902 let ty = self.parse_ty()?;
1904 let mut err = self.diagnostic().struct_span_err_with_code(
1906 "patterns aren't allowed in methods without bodies",
1907 DiagnosticId::Error("E0642".into()),
1909 err.span_suggestion_short_with_applicability(
1911 "give this argument a name or use an underscore to ignore it",
1913 Applicability::MachineApplicable,
1917 // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
1919 node: PatKind::Wild,
1921 id: ast::DUMMY_NODE_ID
1928 Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID })
1931 /// Parse a single function argument
1932 crate fn parse_arg(&mut self) -> PResult<'a, Arg> {
1933 self.parse_arg_general(true, false)
1936 /// Parse an argument in a lambda header e.g., |arg, arg|
1937 fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
1938 let pat = self.parse_pat(Some("argument name"))?;
1939 let t = if self.eat(&token::Colon) {
1943 id: ast::DUMMY_NODE_ID,
1944 node: TyKind::Infer,
1945 span: self.prev_span,
1951 id: ast::DUMMY_NODE_ID
1955 fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
1956 if self.eat(&token::Semi) {
1957 Ok(Some(self.parse_expr()?))
1963 /// Matches token_lit = LIT_INTEGER | ...
1964 fn parse_lit_token(&mut self) -> PResult<'a, LitKind> {
1965 let out = match self.token {
1966 token::Interpolated(ref nt) => match nt.0 {
1967 token::NtExpr(ref v) | token::NtLiteral(ref v) => match v.node {
1968 ExprKind::Lit(ref lit) => { lit.node.clone() }
1969 _ => { return self.unexpected_last(&self.token); }
1971 _ => { return self.unexpected_last(&self.token); }
1973 token::Literal(lit, suf) => {
1974 let diag = Some((self.span, &self.sess.span_diagnostic));
1975 let (suffix_illegal, result) = parse::lit_token(lit, suf, diag);
1979 self.expect_no_suffix(sp, lit.literal_name(), suf)
1984 _ => { return self.unexpected_last(&self.token); }
1991 /// Matches lit = true | false | token_lit
1992 crate fn parse_lit(&mut self) -> PResult<'a, Lit> {
1994 let lit = if self.eat_keyword(keywords::True) {
1996 } else if self.eat_keyword(keywords::False) {
1997 LitKind::Bool(false)
1999 let lit = self.parse_lit_token()?;
2002 Ok(source_map::Spanned { node: lit, span: lo.to(self.prev_span) })
2005 /// matches '-' lit | lit (cf. ast_validation::AstValidator::check_expr_within_pat)
2006 crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
2007 maybe_whole_expr!(self);
2009 let minus_lo = self.span;
2010 let minus_present = self.eat(&token::BinOp(token::Minus));
2012 let literal = self.parse_lit()?;
2013 let hi = self.prev_span;
2014 let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
2017 let minus_hi = self.prev_span;
2018 let unary = self.mk_unary(UnOp::Neg, expr);
2019 Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
2025 fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
2027 token::Ident(ident, _) if self.token.is_path_segment_keyword() => {
2028 let span = self.span;
2030 Ok(Ident::new(ident.name, span))
2032 _ => self.parse_ident(),
2036 fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
2038 token::Ident(ident, false) if ident.name == keywords::Underscore.name() => {
2039 let span = self.span;
2041 Ok(Ident::new(ident.name, span))
2043 _ => self.parse_ident(),
2047 /// Parses qualified path.
2048 /// Assumes that the leading `<` has been parsed already.
2050 /// `qualified_path = <type [as trait_ref]>::path`
2055 /// `<T as U>::F::a<S>` (without disambiguator)
2056 /// `<T as U>::F::a::<S>` (with disambiguator)
2057 fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::Path)> {
2058 let lo = self.prev_span;
2059 let ty = self.parse_ty()?;
2061 // `path` will contain the prefix of the path up to the `>`,
2062 // if any (e.g., `U` in the `<T as U>::*` examples
2063 // above). `path_span` has the span of that path, or an empty
2064 // span in the case of something like `<T>::Bar`.
2065 let (mut path, path_span);
2066 if self.eat_keyword(keywords::As) {
2067 let path_lo = self.span;
2068 path = self.parse_path(PathStyle::Type)?;
2069 path_span = path_lo.to(self.prev_span);
2071 path = ast::Path { segments: Vec::new(), span: syntax_pos::DUMMY_SP };
2072 path_span = self.span.to(self.span);
2075 self.expect(&token::Gt)?;
2076 self.expect(&token::ModSep)?;
2078 let qself = QSelf { ty, path_span, position: path.segments.len() };
2079 self.parse_path_segments(&mut path.segments, style, true)?;
2081 Ok((qself, ast::Path { segments: path.segments, span: lo.to(self.prev_span) }))
2084 /// Parses simple paths.
2086 /// `path = [::] segment+`
2087 /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
2090 /// `a::b::C<D>` (without disambiguator)
2091 /// `a::b::C::<D>` (with disambiguator)
2092 /// `Fn(Args)` (without disambiguator)
2093 /// `Fn::(Args)` (with disambiguator)
2094 pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2095 self.parse_path_common(style, true)
2098 crate fn parse_path_common(&mut self, style: PathStyle, enable_warning: bool)
2099 -> PResult<'a, ast::Path> {
2100 maybe_whole!(self, NtPath, |path| {
2101 if style == PathStyle::Mod &&
2102 path.segments.iter().any(|segment| segment.args.is_some()) {
2103 self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
2108 let lo = self.meta_var_span.unwrap_or(self.span);
2109 let mut segments = Vec::new();
2110 let mod_sep_ctxt = self.span.ctxt();
2111 if self.eat(&token::ModSep) {
2112 segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
2114 self.parse_path_segments(&mut segments, style, enable_warning)?;
2116 Ok(ast::Path { segments, span: lo.to(self.prev_span) })
2119 /// Like `parse_path`, but also supports parsing `Word` meta items into paths for back-compat.
2120 /// This is used when parsing derive macro paths in `#[derive]` attributes.
2121 pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2122 let meta_ident = match self.token {
2123 token::Interpolated(ref nt) => match nt.0 {
2124 token::NtMeta(ref meta) => match meta.node {
2125 ast::MetaItemKind::Word => Some(meta.ident.clone()),
2132 if let Some(path) = meta_ident {
2136 self.parse_path(style)
2139 fn parse_path_segments(&mut self,
2140 segments: &mut Vec<PathSegment>,
2142 enable_warning: bool)
2143 -> PResult<'a, ()> {
2145 segments.push(self.parse_path_segment(style, enable_warning)?);
2147 if self.is_import_coupler() || !self.eat(&token::ModSep) {
2153 fn parse_path_segment(&mut self, style: PathStyle, enable_warning: bool)
2154 -> PResult<'a, PathSegment> {
2155 let ident = self.parse_path_segment_ident()?;
2157 let is_args_start = |token: &token::Token| match *token {
2158 token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren) => true,
2161 let check_args_start = |this: &mut Self| {
2162 this.expected_tokens.extend_from_slice(
2163 &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
2165 is_args_start(&this.token)
2168 Ok(if style == PathStyle::Type && check_args_start(self) ||
2169 style != PathStyle::Mod && self.check(&token::ModSep)
2170 && self.look_ahead(1, |t| is_args_start(t)) {
2171 // Generic arguments are found - `<`, `(`, `::<` or `::(`.
2173 if self.eat(&token::ModSep) && style == PathStyle::Type && enable_warning {
2174 self.diagnostic().struct_span_warn(self.prev_span, "unnecessary path disambiguator")
2175 .span_label(self.prev_span, "try removing `::`").emit();
2178 let args = if self.eat_lt() {
2180 let (args, bindings) = self.parse_generic_args()?;
2182 let span = lo.to(self.prev_span);
2183 AngleBracketedArgs { args, bindings, span }.into()
2187 let inputs = self.parse_seq_to_before_tokens(
2188 &[&token::CloseDelim(token::Paren)],
2189 SeqSep::trailing_allowed(token::Comma),
2190 TokenExpectType::Expect,
2193 let span = lo.to(self.prev_span);
2194 let output = if self.eat(&token::RArrow) {
2195 Some(self.parse_ty_common(false, false)?)
2199 ParenthesisedArgs { inputs, output, span }.into()
2202 PathSegment { ident, args, id: ast::DUMMY_NODE_ID }
2204 // Generic arguments are not found.
2205 PathSegment::from_ident(ident)
2209 crate fn check_lifetime(&mut self) -> bool {
2210 self.expected_tokens.push(TokenType::Lifetime);
2211 self.token.is_lifetime()
2214 /// Parse single lifetime 'a or panic.
2215 crate fn expect_lifetime(&mut self) -> Lifetime {
2216 if let Some(ident) = self.token.lifetime() {
2217 let span = self.span;
2219 Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
2221 self.span_bug(self.span, "not a lifetime")
2225 fn eat_label(&mut self) -> Option<Label> {
2226 if let Some(ident) = self.token.lifetime() {
2227 let span = self.span;
2229 Some(Label { ident: Ident::new(ident.name, span) })
2235 /// Parse mutability (`mut` or nothing).
2236 fn parse_mutability(&mut self) -> Mutability {
2237 if self.eat_keyword(keywords::Mut) {
2240 Mutability::Immutable
2244 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
2245 if let token::Literal(token::Integer(name), None) = self.token {
2247 Ok(Ident::new(name, self.prev_span))
2249 self.parse_ident_common(false)
2253 /// Parse ident (COLON expr)?
2254 fn parse_field(&mut self) -> PResult<'a, Field> {
2255 let attrs = self.parse_outer_attributes()?;
2258 // Check if a colon exists one ahead. This means we're parsing a fieldname.
2259 let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
2260 let fieldname = self.parse_field_name()?;
2262 (fieldname, self.parse_expr()?, false)
2264 let fieldname = self.parse_ident_common(false)?;
2266 // Mimic `x: x` for the `x` field shorthand.
2267 let path = ast::Path::from_ident(fieldname);
2268 let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
2269 (fieldname, expr, true)
2273 span: lo.to(expr.span),
2276 attrs: attrs.into(),
2280 fn mk_expr(&mut self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
2281 P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID })
2284 fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
2285 ExprKind::Unary(unop, expr)
2288 fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2289 ExprKind::Binary(binop, lhs, rhs)
2292 fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
2293 ExprKind::Call(f, args)
2296 fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
2297 ExprKind::Index(expr, idx)
2300 fn mk_range(&mut self,
2301 start: Option<P<Expr>>,
2302 end: Option<P<Expr>>,
2303 limits: RangeLimits)
2304 -> PResult<'a, ast::ExprKind> {
2305 if end.is_none() && limits == RangeLimits::Closed {
2306 Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd))
2308 Ok(ExprKind::Range(start, end, limits))
2312 fn mk_assign_op(&mut self, binop: ast::BinOp,
2313 lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2314 ExprKind::AssignOp(binop, lhs, rhs)
2317 pub fn mk_mac_expr(&mut self, span: Span, m: Mac_, attrs: ThinVec<Attribute>) -> P<Expr> {
2319 id: ast::DUMMY_NODE_ID,
2320 node: ExprKind::Mac(source_map::Spanned {node: m, span: span}),
2326 fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, ThinTokenStream)> {
2327 let delim = match self.token {
2328 token::OpenDelim(delim) => delim,
2330 let msg = "expected open delimiter";
2331 let mut err = self.fatal(msg);
2332 err.span_label(self.span, msg);
2336 let tts = match self.parse_token_tree() {
2337 TokenTree::Delimited(_, _, tts) => tts,
2338 _ => unreachable!(),
2340 let delim = match delim {
2341 token::Paren => MacDelimiter::Parenthesis,
2342 token::Bracket => MacDelimiter::Bracket,
2343 token::Brace => MacDelimiter::Brace,
2344 token::NoDelim => self.bug("unexpected no delimiter"),
2346 Ok((delim, tts.stream().into()))
2349 /// At the bottom (top?) of the precedence hierarchy,
2350 /// parse things like parenthesized exprs,
2351 /// macros, return, etc.
2353 /// N.B., this does not parse outer attributes,
2354 /// and is private because it only works
2355 /// correctly if called from parse_dot_or_call_expr().
2356 fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
2357 maybe_whole_expr!(self);
2359 // Outer attributes are already parsed and will be
2360 // added to the return value after the fact.
2362 // Therefore, prevent sub-parser from parsing
2363 // attributes by giving them a empty "already parsed" list.
2364 let mut attrs = ThinVec::new();
2367 let mut hi = self.span;
2371 // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2373 token::OpenDelim(token::Paren) => {
2376 attrs.extend(self.parse_inner_attributes()?);
2378 // (e) is parenthesized e
2379 // (e,) is a tuple with only one field, e
2380 let mut es = vec![];
2381 let mut trailing_comma = false;
2382 while self.token != token::CloseDelim(token::Paren) {
2383 es.push(self.parse_expr()?);
2384 self.expect_one_of(&[], &[token::Comma, token::CloseDelim(token::Paren)])?;
2385 if self.eat(&token::Comma) {
2386 trailing_comma = true;
2388 trailing_comma = false;
2394 hi = self.prev_span;
2395 ex = if es.len() == 1 && !trailing_comma {
2396 ExprKind::Paren(es.into_iter().nth(0).unwrap())
2401 token::OpenDelim(token::Brace) => {
2402 return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
2404 token::BinOp(token::Or) | token::OrOr => {
2405 return self.parse_lambda_expr(attrs);
2407 token::OpenDelim(token::Bracket) => {
2410 attrs.extend(self.parse_inner_attributes()?);
2412 if self.eat(&token::CloseDelim(token::Bracket)) {
2414 ex = ExprKind::Array(Vec::new());
2417 let first_expr = self.parse_expr()?;
2418 if self.eat(&token::Semi) {
2419 // Repeating array syntax: [ 0; 512 ]
2420 let count = AnonConst {
2421 id: ast::DUMMY_NODE_ID,
2422 value: self.parse_expr()?,
2424 self.expect(&token::CloseDelim(token::Bracket))?;
2425 ex = ExprKind::Repeat(first_expr, count);
2426 } else if self.eat(&token::Comma) {
2427 // Vector with two or more elements.
2428 let remaining_exprs = self.parse_seq_to_end(
2429 &token::CloseDelim(token::Bracket),
2430 SeqSep::trailing_allowed(token::Comma),
2431 |p| Ok(p.parse_expr()?)
2433 let mut exprs = vec![first_expr];
2434 exprs.extend(remaining_exprs);
2435 ex = ExprKind::Array(exprs);
2437 // Vector with one element.
2438 self.expect(&token::CloseDelim(token::Bracket))?;
2439 ex = ExprKind::Array(vec![first_expr]);
2442 hi = self.prev_span;
2446 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
2448 return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
2450 if self.span.rust_2018() && self.check_keyword(keywords::Async)
2452 if self.is_async_block() { // check for `async {` and `async move {`
2453 return self.parse_async_block(attrs);
2455 return self.parse_lambda_expr(attrs);
2458 if self.check_keyword(keywords::Move) || self.check_keyword(keywords::Static) {
2459 return self.parse_lambda_expr(attrs);
2461 if self.eat_keyword(keywords::If) {
2462 return self.parse_if_expr(attrs);
2464 if self.eat_keyword(keywords::For) {
2465 let lo = self.prev_span;
2466 return self.parse_for_expr(None, lo, attrs);
2468 if self.eat_keyword(keywords::While) {
2469 let lo = self.prev_span;
2470 return self.parse_while_expr(None, lo, attrs);
2472 if let Some(label) = self.eat_label() {
2473 let lo = label.ident.span;
2474 self.expect(&token::Colon)?;
2475 if self.eat_keyword(keywords::While) {
2476 return self.parse_while_expr(Some(label), lo, attrs)
2478 if self.eat_keyword(keywords::For) {
2479 return self.parse_for_expr(Some(label), lo, attrs)
2481 if self.eat_keyword(keywords::Loop) {
2482 return self.parse_loop_expr(Some(label), lo, attrs)
2484 if self.token == token::OpenDelim(token::Brace) {
2485 return self.parse_block_expr(Some(label),
2487 BlockCheckMode::Default,
2490 let msg = "expected `while`, `for`, `loop` or `{` after a label";
2491 let mut err = self.fatal(msg);
2492 err.span_label(self.span, msg);
2495 if self.eat_keyword(keywords::Loop) {
2496 let lo = self.prev_span;
2497 return self.parse_loop_expr(None, lo, attrs);
2499 if self.eat_keyword(keywords::Continue) {
2500 let label = self.eat_label();
2501 let ex = ExprKind::Continue(label);
2502 let hi = self.prev_span;
2503 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2505 if self.eat_keyword(keywords::Match) {
2506 let match_sp = self.prev_span;
2507 return self.parse_match_expr(attrs).map_err(|mut err| {
2508 err.span_label(match_sp, "while parsing this match expression");
2512 if self.eat_keyword(keywords::Unsafe) {
2513 return self.parse_block_expr(
2516 BlockCheckMode::Unsafe(ast::UserProvided),
2519 if self.is_do_catch_block() {
2520 let mut db = self.fatal("found removed `do catch` syntax");
2521 db.help("Following RFC #2388, the new non-placeholder syntax is `try`");
2524 if self.is_try_block() {
2526 assert!(self.eat_keyword(keywords::Try));
2527 return self.parse_try_block(lo, attrs);
2529 if self.eat_keyword(keywords::Return) {
2530 if self.token.can_begin_expr() {
2531 let e = self.parse_expr()?;
2533 ex = ExprKind::Ret(Some(e));
2535 ex = ExprKind::Ret(None);
2537 } else if self.eat_keyword(keywords::Break) {
2538 let label = self.eat_label();
2539 let e = if self.token.can_begin_expr()
2540 && !(self.token == token::OpenDelim(token::Brace)
2541 && self.restrictions.contains(
2542 Restrictions::NO_STRUCT_LITERAL)) {
2543 Some(self.parse_expr()?)
2547 ex = ExprKind::Break(label, e);
2548 hi = self.prev_span;
2549 } else if self.eat_keyword(keywords::Yield) {
2550 if self.token.can_begin_expr() {
2551 let e = self.parse_expr()?;
2553 ex = ExprKind::Yield(Some(e));
2555 ex = ExprKind::Yield(None);
2557 } else if self.token.is_keyword(keywords::Let) {
2558 // Catch this syntax error here, instead of in `parse_ident`, so
2559 // that we can explicitly mention that let is not to be used as an expression
2560 let mut db = self.fatal("expected expression, found statement (`let`)");
2561 db.span_label(self.span, "expected expression");
2562 db.note("variable declaration using `let` is a statement");
2564 } else if self.token.is_path_start() {
2565 let pth = self.parse_path(PathStyle::Expr)?;
2567 // `!`, as an operator, is prefix, so we know this isn't that
2568 if self.eat(&token::Not) {
2569 // MACRO INVOCATION expression
2570 let (delim, tts) = self.expect_delimited_token_tree()?;
2571 let hi = self.prev_span;
2572 let node = Mac_ { path: pth, tts, delim };
2573 return Ok(self.mk_mac_expr(lo.to(hi), node, attrs))
2575 if self.check(&token::OpenDelim(token::Brace)) {
2576 // This is a struct literal, unless we're prohibited
2577 // from parsing struct literals here.
2578 let prohibited = self.restrictions.contains(
2579 Restrictions::NO_STRUCT_LITERAL
2582 return self.parse_struct_expr(lo, pth, attrs);
2587 ex = ExprKind::Path(None, pth);
2589 match self.parse_literal_maybe_minus() {
2592 ex = expr.node.clone();
2595 self.cancel(&mut err);
2596 let msg = format!("expected expression, found {}",
2597 self.this_token_descr());
2598 let mut err = self.fatal(&msg);
2599 err.span_label(self.span, "expected expression");
2607 let expr = Expr { node: ex, span: lo.to(hi), id: ast::DUMMY_NODE_ID, attrs };
2608 let expr = self.maybe_recover_from_bad_qpath(expr, true)?;
2613 fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Attribute>)
2614 -> PResult<'a, P<Expr>> {
2615 let struct_sp = lo.to(self.prev_span);
2617 let mut fields = Vec::new();
2618 let mut base = None;
2620 attrs.extend(self.parse_inner_attributes()?);
2622 while self.token != token::CloseDelim(token::Brace) {
2623 if self.eat(&token::DotDot) {
2624 let exp_span = self.prev_span;
2625 match self.parse_expr() {
2631 self.recover_stmt();
2634 if self.token == token::Comma {
2635 let mut err = self.sess.span_diagnostic.mut_span_err(
2636 exp_span.to(self.prev_span),
2637 "cannot use a comma after the base struct",
2639 err.span_suggestion_short_with_applicability(
2641 "remove this comma",
2643 Applicability::MachineApplicable
2645 err.note("the base struct must always be the last field");
2647 self.recover_stmt();
2652 match self.parse_field() {
2653 Ok(f) => fields.push(f),
2655 e.span_label(struct_sp, "while parsing this struct");
2658 // If the next token is a comma, then try to parse
2659 // what comes next as additional fields, rather than
2660 // bailing out until next `}`.
2661 if self.token != token::Comma {
2662 self.recover_stmt();
2668 match self.expect_one_of(&[token::Comma],
2669 &[token::CloseDelim(token::Brace)]) {
2673 self.recover_stmt();
2679 let span = lo.to(self.span);
2680 self.expect(&token::CloseDelim(token::Brace))?;
2681 return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
2684 fn parse_or_use_outer_attributes(&mut self,
2685 already_parsed_attrs: Option<ThinVec<Attribute>>)
2686 -> PResult<'a, ThinVec<Attribute>> {
2687 if let Some(attrs) = already_parsed_attrs {
2690 self.parse_outer_attributes().map(|a| a.into())
2694 /// Parse a block or unsafe block
2695 fn parse_block_expr(&mut self, opt_label: Option<Label>,
2696 lo: Span, blk_mode: BlockCheckMode,
2697 outer_attrs: ThinVec<Attribute>)
2698 -> PResult<'a, P<Expr>> {
2699 self.expect(&token::OpenDelim(token::Brace))?;
2701 let mut attrs = outer_attrs;
2702 attrs.extend(self.parse_inner_attributes()?);
2704 let blk = self.parse_block_tail(lo, blk_mode)?;
2705 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs));
2708 /// parse a.b or a(13) or a[4] or just a
2709 fn parse_dot_or_call_expr(&mut self,
2710 already_parsed_attrs: Option<ThinVec<Attribute>>)
2711 -> PResult<'a, P<Expr>> {
2712 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2714 let b = self.parse_bottom_expr();
2715 let (span, b) = self.interpolated_or_expr_span(b)?;
2716 self.parse_dot_or_call_expr_with(b, span, attrs)
2719 fn parse_dot_or_call_expr_with(&mut self,
2722 mut attrs: ThinVec<Attribute>)
2723 -> PResult<'a, P<Expr>> {
2724 // Stitch the list of outer attributes onto the return value.
2725 // A little bit ugly, but the best way given the current code
2727 self.parse_dot_or_call_expr_with_(e0, lo)
2729 expr.map(|mut expr| {
2730 attrs.extend::<Vec<_>>(expr.attrs.into());
2733 ExprKind::If(..) | ExprKind::IfLet(..) => {
2734 if !expr.attrs.is_empty() {
2735 // Just point to the first attribute in there...
2736 let span = expr.attrs[0].span;
2739 "attributes are not yet allowed on `if` \
2750 // Assuming we have just parsed `.`, continue parsing into an expression.
2751 fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2752 let segment = self.parse_path_segment(PathStyle::Expr, true)?;
2753 Ok(match self.token {
2754 token::OpenDelim(token::Paren) => {
2755 // Method call `expr.f()`
2756 let mut args = self.parse_unspanned_seq(
2757 &token::OpenDelim(token::Paren),
2758 &token::CloseDelim(token::Paren),
2759 SeqSep::trailing_allowed(token::Comma),
2760 |p| Ok(p.parse_expr()?)
2762 args.insert(0, self_arg);
2764 let span = lo.to(self.prev_span);
2765 self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
2768 // Field access `expr.f`
2769 if let Some(args) = segment.args {
2770 self.span_err(args.span(),
2771 "field expressions may not have generic arguments");
2774 let span = lo.to(self.prev_span);
2775 self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
2780 fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2785 while self.eat(&token::Question) {
2786 let hi = self.prev_span;
2787 e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
2791 if self.eat(&token::Dot) {
2793 token::Ident(..) => {
2794 e = self.parse_dot_suffix(e, lo)?;
2796 token::Literal(token::Integer(name), _) => {
2797 let span = self.span;
2799 let field = ExprKind::Field(e, Ident::new(name, span));
2800 e = self.mk_expr(lo.to(span), field, ThinVec::new());
2802 token::Literal(token::Float(n), _suf) => {
2804 let fstr = n.as_str();
2805 let mut err = self.diagnostic()
2806 .struct_span_err(self.prev_span, &format!("unexpected token: `{}`", n));
2807 err.span_label(self.prev_span, "unexpected token");
2808 if fstr.chars().all(|x| "0123456789.".contains(x)) {
2809 let float = match fstr.parse::<f64>().ok() {
2813 let sugg = pprust::to_string(|s| {
2814 use print::pprust::PrintState;
2818 s.print_usize(float.trunc() as usize)?;
2821 s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
2823 err.span_suggestion_with_applicability(
2824 lo.to(self.prev_span),
2825 "try parenthesizing the first index",
2827 Applicability::MachineApplicable
2834 // FIXME Could factor this out into non_fatal_unexpected or something.
2835 let actual = self.this_token_to_string();
2836 self.span_err(self.span, &format!("unexpected token: `{}`", actual));
2841 if self.expr_is_complete(&e) { break; }
2844 token::OpenDelim(token::Paren) => {
2845 let es = self.parse_unspanned_seq(
2846 &token::OpenDelim(token::Paren),
2847 &token::CloseDelim(token::Paren),
2848 SeqSep::trailing_allowed(token::Comma),
2849 |p| Ok(p.parse_expr()?)
2851 hi = self.prev_span;
2853 let nd = self.mk_call(e, es);
2854 e = self.mk_expr(lo.to(hi), nd, ThinVec::new());
2858 // Could be either an index expression or a slicing expression.
2859 token::OpenDelim(token::Bracket) => {
2861 let ix = self.parse_expr()?;
2863 self.expect(&token::CloseDelim(token::Bracket))?;
2864 let index = self.mk_index(e, ix);
2865 e = self.mk_expr(lo.to(hi), index, ThinVec::new())
2873 crate fn process_potential_macro_variable(&mut self) {
2874 let (token, span) = match self.token {
2875 token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
2876 self.look_ahead(1, |t| t.is_ident()) => {
2878 let name = match self.token {
2879 token::Ident(ident, _) => ident,
2882 let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
2883 err.span_label(self.span, "unknown macro variable");
2888 token::Interpolated(ref nt) => {
2889 self.meta_var_span = Some(self.span);
2890 // Interpolated identifier and lifetime tokens are replaced with usual identifier
2891 // and lifetime tokens, so the former are never encountered during normal parsing.
2893 token::NtIdent(ident, is_raw) => (token::Ident(ident, is_raw), ident.span),
2894 token::NtLifetime(ident) => (token::Lifetime(ident), ident.span),
2904 /// parse a single token tree from the input.
2905 crate fn parse_token_tree(&mut self) -> TokenTree {
2907 token::OpenDelim(..) => {
2908 let frame = mem::replace(&mut self.token_cursor.frame,
2909 self.token_cursor.stack.pop().unwrap());
2910 self.span = frame.span.entire();
2912 TokenTree::Delimited(
2915 frame.tree_cursor.original_stream().into(),
2918 token::CloseDelim(_) | token::Eof => unreachable!(),
2920 let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span);
2922 TokenTree::Token(span, token)
2927 // parse a stream of tokens into a list of TokenTree's,
2929 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
2930 let mut tts = Vec::new();
2931 while self.token != token::Eof {
2932 tts.push(self.parse_token_tree());
2937 pub fn parse_tokens(&mut self) -> TokenStream {
2938 let mut result = Vec::new();
2941 token::Eof | token::CloseDelim(..) => break,
2942 _ => result.push(self.parse_token_tree().into()),
2945 TokenStream::new(result)
2948 /// Parse a prefix-unary-operator expr
2949 fn parse_prefix_expr(&mut self,
2950 already_parsed_attrs: Option<ThinVec<Attribute>>)
2951 -> PResult<'a, P<Expr>> {
2952 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2954 // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2955 let (hi, ex) = match self.token {
2958 let e = self.parse_prefix_expr(None);
2959 let (span, e) = self.interpolated_or_expr_span(e)?;
2960 (lo.to(span), self.mk_unary(UnOp::Not, e))
2962 // Suggest `!` for bitwise negation when encountering a `~`
2965 let e = self.parse_prefix_expr(None);
2966 let (span, e) = self.interpolated_or_expr_span(e)?;
2967 let span_of_tilde = lo;
2968 let mut err = self.diagnostic()
2969 .struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator");
2970 err.span_suggestion_short_with_applicability(
2972 "use `!` to perform bitwise negation",
2974 Applicability::MachineApplicable
2977 (lo.to(span), self.mk_unary(UnOp::Not, e))
2979 token::BinOp(token::Minus) => {
2981 let e = self.parse_prefix_expr(None);
2982 let (span, e) = self.interpolated_or_expr_span(e)?;
2983 (lo.to(span), self.mk_unary(UnOp::Neg, e))
2985 token::BinOp(token::Star) => {
2987 let e = self.parse_prefix_expr(None);
2988 let (span, e) = self.interpolated_or_expr_span(e)?;
2989 (lo.to(span), self.mk_unary(UnOp::Deref, e))
2991 token::BinOp(token::And) | token::AndAnd => {
2993 let m = self.parse_mutability();
2994 let e = self.parse_prefix_expr(None);
2995 let (span, e) = self.interpolated_or_expr_span(e)?;
2996 (lo.to(span), ExprKind::AddrOf(m, e))
2998 token::Ident(..) if self.token.is_keyword(keywords::In) => {
3000 let place = self.parse_expr_res(
3001 Restrictions::NO_STRUCT_LITERAL,
3004 let blk = self.parse_block()?;
3005 let span = blk.span;
3006 let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new());
3007 (lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr))
3009 token::Ident(..) if self.token.is_keyword(keywords::Box) => {
3011 let e = self.parse_prefix_expr(None);
3012 let (span, e) = self.interpolated_or_expr_span(e)?;
3013 (lo.to(span), ExprKind::Box(e))
3015 token::Ident(..) if self.token.is_ident_named("not") => {
3016 // `not` is just an ordinary identifier in Rust-the-language,
3017 // but as `rustc`-the-compiler, we can issue clever diagnostics
3018 // for confused users who really want to say `!`
3019 let token_cannot_continue_expr = |t: &token::Token| match *t {
3020 // These tokens can start an expression after `!`, but
3021 // can't continue an expression after an ident
3022 token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw),
3023 token::Literal(..) | token::Pound => true,
3024 token::Interpolated(ref nt) => match nt.0 {
3025 token::NtIdent(..) | token::NtExpr(..) |
3026 token::NtBlock(..) | token::NtPath(..) => true,
3031 let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
3032 if cannot_continue_expr {
3034 // Emit the error ...
3035 let mut err = self.diagnostic()
3036 .struct_span_err(self.span,
3037 &format!("unexpected {} after identifier",
3038 self.this_token_descr()));
3039 // span the `not` plus trailing whitespace to avoid
3040 // trailing whitespace after the `!` in our suggestion
3041 let to_replace = self.sess.source_map()
3042 .span_until_non_whitespace(lo.to(self.span));
3043 err.span_suggestion_short_with_applicability(
3045 "use `!` to perform logical negation",
3047 Applicability::MachineApplicable
3050 // —and recover! (just as if we were in the block
3051 // for the `token::Not` arm)
3052 let e = self.parse_prefix_expr(None);
3053 let (span, e) = self.interpolated_or_expr_span(e)?;
3054 (lo.to(span), self.mk_unary(UnOp::Not, e))
3056 return self.parse_dot_or_call_expr(Some(attrs));
3059 _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
3061 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
3064 /// Parse an associative expression
3066 /// This parses an expression accounting for associativity and precedence of the operators in
3069 fn parse_assoc_expr(&mut self,
3070 already_parsed_attrs: Option<ThinVec<Attribute>>)
3071 -> PResult<'a, P<Expr>> {
3072 self.parse_assoc_expr_with(0, already_parsed_attrs.into())
3075 /// Parse an associative expression with operators of at least `min_prec` precedence
3076 fn parse_assoc_expr_with(&mut self,
3079 -> PResult<'a, P<Expr>> {
3080 let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
3083 let attrs = match lhs {
3084 LhsExpr::AttributesParsed(attrs) => Some(attrs),
3087 if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token) {
3088 return self.parse_prefix_range_expr(attrs);
3090 self.parse_prefix_expr(attrs)?
3094 if self.expr_is_complete(&lhs) {
3095 // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
3098 self.expected_tokens.push(TokenType::Operator);
3099 while let Some(op) = AssocOp::from_token(&self.token) {
3101 // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
3102 // it refers to. Interpolated identifiers are unwrapped early and never show up here
3103 // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
3104 // it as "interpolated", it doesn't change the answer for non-interpolated idents.
3105 let lhs_span = match (self.prev_token_kind, &lhs.node) {
3106 (PrevTokenKind::Interpolated, _) => self.prev_span,
3107 (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
3108 if path.segments.len() == 1 => self.prev_span,
3112 let cur_op_span = self.span;
3113 let restrictions = if op.is_assign_like() {
3114 self.restrictions & Restrictions::NO_STRUCT_LITERAL
3118 if op.precedence() < min_prec {
3121 // Check for deprecated `...` syntax
3122 if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
3123 self.err_dotdotdot_syntax(self.span);
3127 if op.is_comparison() {
3128 self.check_no_chained_comparison(&lhs, &op);
3131 if op == AssocOp::As {
3132 lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
3134 } else if op == AssocOp::Colon {
3135 lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) {
3138 err.span_label(self.span,
3139 "expecting a type here because of type ascription");
3140 let cm = self.sess.source_map();
3141 let cur_pos = cm.lookup_char_pos(self.span.lo());
3142 let op_pos = cm.lookup_char_pos(cur_op_span.hi());
3143 if cur_pos.line != op_pos.line {
3144 err.span_suggestion_with_applicability(
3146 "try using a semicolon",
3148 Applicability::MaybeIncorrect // speculative
3155 } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
3156 // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
3157 // generalise it to the Fixity::None code.
3159 // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
3160 // two variants are handled with `parse_prefix_range_expr` call above.
3161 let rhs = if self.is_at_start_of_range_notation_rhs() {
3162 Some(self.parse_assoc_expr_with(op.precedence() + 1,
3163 LhsExpr::NotYetParsed)?)
3167 let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
3172 let limits = if op == AssocOp::DotDot {
3173 RangeLimits::HalfOpen
3178 let r = self.mk_range(Some(lhs), rhs, limits)?;
3179 lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
3183 let rhs = match op.fixity() {
3184 Fixity::Right => self.with_res(
3185 restrictions - Restrictions::STMT_EXPR,
3187 this.parse_assoc_expr_with(op.precedence(),
3188 LhsExpr::NotYetParsed)
3190 Fixity::Left => self.with_res(
3191 restrictions - Restrictions::STMT_EXPR,
3193 this.parse_assoc_expr_with(op.precedence() + 1,
3194 LhsExpr::NotYetParsed)
3196 // We currently have no non-associative operators that are not handled above by
3197 // the special cases. The code is here only for future convenience.
3198 Fixity::None => self.with_res(
3199 restrictions - Restrictions::STMT_EXPR,
3201 this.parse_assoc_expr_with(op.precedence() + 1,
3202 LhsExpr::NotYetParsed)
3206 let span = lhs_span.to(rhs.span);
3208 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
3209 AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
3210 AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
3211 AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
3212 AssocOp::Greater | AssocOp::GreaterEqual => {
3213 let ast_op = op.to_ast_binop().unwrap();
3214 let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
3215 self.mk_expr(span, binary, ThinVec::new())
3218 self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
3219 AssocOp::ObsoleteInPlace =>
3220 self.mk_expr(span, ExprKind::ObsoleteInPlace(lhs, rhs), ThinVec::new()),
3221 AssocOp::AssignOp(k) => {
3223 token::Plus => BinOpKind::Add,
3224 token::Minus => BinOpKind::Sub,
3225 token::Star => BinOpKind::Mul,
3226 token::Slash => BinOpKind::Div,
3227 token::Percent => BinOpKind::Rem,
3228 token::Caret => BinOpKind::BitXor,
3229 token::And => BinOpKind::BitAnd,
3230 token::Or => BinOpKind::BitOr,
3231 token::Shl => BinOpKind::Shl,
3232 token::Shr => BinOpKind::Shr,
3234 let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
3235 self.mk_expr(span, aopexpr, ThinVec::new())
3237 AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
3238 self.bug("AssocOp should have been handled by special case")
3242 if op.fixity() == Fixity::None { break }
3247 fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
3248 expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
3249 -> PResult<'a, P<Expr>> {
3250 let mk_expr = |this: &mut Self, rhs: P<Ty>| {
3251 this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
3254 // Save the state of the parser before parsing type normally, in case there is a
3255 // LessThan comparison after this cast.
3256 let parser_snapshot_before_type = self.clone();
3257 match self.parse_ty_no_plus() {
3259 Ok(mk_expr(self, rhs))
3261 Err(mut type_err) => {
3262 // Rewind to before attempting to parse the type with generics, to recover
3263 // from situations like `x as usize < y` in which we first tried to parse
3264 // `usize < y` as a type with generic arguments.
3265 let parser_snapshot_after_type = self.clone();
3266 mem::replace(self, parser_snapshot_before_type);
3268 match self.parse_path(PathStyle::Expr) {
3270 let (op_noun, op_verb) = match self.token {
3271 token::Lt => ("comparison", "comparing"),
3272 token::BinOp(token::Shl) => ("shift", "shifting"),
3274 // We can end up here even without `<` being the next token, for
3275 // example because `parse_ty_no_plus` returns `Err` on keywords,
3276 // but `parse_path` returns `Ok` on them due to error recovery.
3277 // Return original error and parser state.
3278 mem::replace(self, parser_snapshot_after_type);
3279 return Err(type_err);
3283 // Successfully parsed the type path leaving a `<` yet to parse.
3286 // Report non-fatal diagnostics, keep `x as usize` as an expression
3287 // in AST and continue parsing.
3288 let msg = format!("`<` is interpreted as a start of generic \
3289 arguments for `{}`, not a {}", path, op_noun);
3290 let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
3291 err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span),
3292 "interpreted as generic arguments");
3293 err.span_label(self.span, format!("not interpreted as {}", op_noun));
3295 let expr = mk_expr(self, P(Ty {
3297 node: TyKind::Path(None, path),
3298 id: ast::DUMMY_NODE_ID
3301 let expr_str = self.sess.source_map().span_to_snippet(expr.span)
3302 .unwrap_or_else(|_| pprust::expr_to_string(&expr));
3303 err.span_suggestion_with_applicability(
3305 &format!("try {} the cast value", op_verb),
3306 format!("({})", expr_str),
3307 Applicability::MachineApplicable
3313 Err(mut path_err) => {
3314 // Couldn't parse as a path, return original error and parser state.
3316 mem::replace(self, parser_snapshot_after_type);
3324 /// Produce an error if comparison operators are chained (RFC #558).
3325 /// We only need to check lhs, not rhs, because all comparison ops
3326 /// have same precedence and are left-associative
3327 fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
3328 debug_assert!(outer_op.is_comparison(),
3329 "check_no_chained_comparison: {:?} is not comparison",
3332 ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
3333 // respan to include both operators
3334 let op_span = op.span.to(self.span);
3335 let mut err = self.diagnostic().struct_span_err(op_span,
3336 "chained comparison operators require parentheses");
3337 if op.node == BinOpKind::Lt &&
3338 *outer_op == AssocOp::Less || // Include `<` to provide this recommendation
3339 *outer_op == AssocOp::Greater // even in a case like the following:
3340 { // Foo<Bar<Baz<Qux, ()>>>
3342 "use `::<...>` instead of `<...>` if you meant to specify type arguments");
3343 err.help("or use `(...)` if you meant to specify fn arguments");
3351 /// Parse prefix-forms of range notation: `..expr`, `..`, `..=expr`
3352 fn parse_prefix_range_expr(&mut self,
3353 already_parsed_attrs: Option<ThinVec<Attribute>>)
3354 -> PResult<'a, P<Expr>> {
3355 // Check for deprecated `...` syntax
3356 if self.token == token::DotDotDot {
3357 self.err_dotdotdot_syntax(self.span);
3360 debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token),
3361 "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
3363 let tok = self.token.clone();
3364 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
3366 let mut hi = self.span;
3368 let opt_end = if self.is_at_start_of_range_notation_rhs() {
3369 // RHS must be parsed with more associativity than the dots.
3370 let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
3371 Some(self.parse_assoc_expr_with(next_prec,
3372 LhsExpr::NotYetParsed)
3380 let limits = if tok == token::DotDot {
3381 RangeLimits::HalfOpen
3386 let r = self.mk_range(None, opt_end, limits)?;
3387 Ok(self.mk_expr(lo.to(hi), r, attrs))
3390 fn is_at_start_of_range_notation_rhs(&self) -> bool {
3391 if self.token.can_begin_expr() {
3392 // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
3393 if self.token == token::OpenDelim(token::Brace) {
3394 return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
3402 /// Parse an 'if' or 'if let' expression ('if' token already eaten)
3403 fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3404 if self.check_keyword(keywords::Let) {
3405 return self.parse_if_let_expr(attrs);
3407 let lo = self.prev_span;
3408 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3410 // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
3411 // verify that the last statement is either an implicit return (no `;`) or an explicit
3412 // return. This won't catch blocks with an explicit `return`, but that would be caught by
3413 // the dead code lint.
3414 if self.eat_keyword(keywords::Else) || !cond.returns() {
3415 let sp = self.sess.source_map().next_point(lo);
3416 let mut err = self.diagnostic()
3417 .struct_span_err(sp, "missing condition for `if` statemement");
3418 err.span_label(sp, "expected if condition here");
3421 let not_block = self.token != token::OpenDelim(token::Brace);
3422 let thn = self.parse_block().map_err(|mut err| {
3424 err.span_label(lo, "this `if` statement has a condition, but no block");
3428 let mut els: Option<P<Expr>> = None;
3429 let mut hi = thn.span;
3430 if self.eat_keyword(keywords::Else) {
3431 let elexpr = self.parse_else_expr()?;
3435 Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
3438 /// Parse an 'if let' expression ('if' token already eaten)
3439 fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
3440 -> PResult<'a, P<Expr>> {
3441 let lo = self.prev_span;
3442 self.expect_keyword(keywords::Let)?;
3443 let pats = self.parse_pats()?;
3444 self.expect(&token::Eq)?;
3445 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3446 let thn = self.parse_block()?;
3447 let (hi, els) = if self.eat_keyword(keywords::Else) {
3448 let expr = self.parse_else_expr()?;
3449 (expr.span, Some(expr))
3453 Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
3456 // `move |args| expr`
3457 fn parse_lambda_expr(&mut self,
3458 attrs: ThinVec<Attribute>)
3459 -> PResult<'a, P<Expr>>
3462 let movability = if self.eat_keyword(keywords::Static) {
3467 let asyncness = if self.span.rust_2018() {
3468 self.parse_asyncness()
3472 let capture_clause = if self.eat_keyword(keywords::Move) {
3477 let decl = self.parse_fn_block_decl()?;
3478 let decl_hi = self.prev_span;
3479 let body = match decl.output {
3480 FunctionRetTy::Default(_) => {
3481 let restrictions = self.restrictions - Restrictions::STMT_EXPR;
3482 self.parse_expr_res(restrictions, None)?
3485 // If an explicit return type is given, require a
3486 // block to appear (RFC 968).
3487 let body_lo = self.span;
3488 self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
3494 ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
3498 // `else` token already eaten
3499 fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
3500 if self.eat_keyword(keywords::If) {
3501 return self.parse_if_expr(ThinVec::new());
3503 let blk = self.parse_block()?;
3504 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
3508 /// Parse a 'for' .. 'in' expression ('for' token already eaten)
3509 fn parse_for_expr(&mut self, opt_label: Option<Label>,
3511 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3512 // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
3514 let pat = self.parse_top_level_pat()?;
3515 if !self.eat_keyword(keywords::In) {
3516 let in_span = self.prev_span.between(self.span);
3517 let mut err = self.sess.span_diagnostic
3518 .struct_span_err(in_span, "missing `in` in `for` loop");
3519 err.span_suggestion_short_with_applicability(
3520 in_span, "try adding `in` here", " in ".into(),
3521 // has been misleading, at least in the past (closed Issue #48492)
3522 Applicability::MaybeIncorrect
3526 let in_span = self.prev_span;
3527 if self.eat_keyword(keywords::In) {
3528 // a common typo: `for _ in in bar {}`
3529 let mut err = self.sess.span_diagnostic.struct_span_err(
3531 "expected iterable, found keyword `in`",
3533 err.span_suggestion_short_with_applicability(
3534 in_span.until(self.prev_span),
3535 "remove the duplicated `in`",
3537 Applicability::MachineApplicable,
3539 err.note("if you meant to use emplacement syntax, it is obsolete (for now, anyway)");
3540 err.note("for more information on the status of emplacement syntax, see <\
3541 https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>");
3544 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3545 let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
3546 attrs.extend(iattrs);
3548 let hi = self.prev_span;
3549 Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
3552 /// Parse a 'while' or 'while let' expression ('while' token already eaten)
3553 fn parse_while_expr(&mut self, opt_label: Option<Label>,
3555 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3556 if self.token.is_keyword(keywords::Let) {
3557 return self.parse_while_let_expr(opt_label, span_lo, attrs);
3559 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3560 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3561 attrs.extend(iattrs);
3562 let span = span_lo.to(body.span);
3563 return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs));
3566 /// Parse a 'while let' expression ('while' token already eaten)
3567 fn parse_while_let_expr(&mut self, opt_label: Option<Label>,
3569 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3570 self.expect_keyword(keywords::Let)?;
3571 let pats = self.parse_pats()?;
3572 self.expect(&token::Eq)?;
3573 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3574 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3575 attrs.extend(iattrs);
3576 let span = span_lo.to(body.span);
3577 return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
3580 // parse `loop {...}`, `loop` token already eaten
3581 fn parse_loop_expr(&mut self, opt_label: Option<Label>,
3583 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3584 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3585 attrs.extend(iattrs);
3586 let span = span_lo.to(body.span);
3587 Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
3590 /// Parse an `async move {...}` expression
3591 pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>)
3592 -> PResult<'a, P<Expr>>
3594 let span_lo = self.span;
3595 self.expect_keyword(keywords::Async)?;
3596 let capture_clause = if self.eat_keyword(keywords::Move) {
3601 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3602 attrs.extend(iattrs);
3604 span_lo.to(body.span),
3605 ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs))
3608 /// Parse a `try {...}` expression (`try` token already eaten)
3609 fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
3610 -> PResult<'a, P<Expr>>
3612 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3613 attrs.extend(iattrs);
3614 Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
3617 // `match` token already eaten
3618 fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3619 let match_span = self.prev_span;
3620 let lo = self.prev_span;
3621 let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL,
3623 if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
3624 if self.token == token::Token::Semi {
3625 e.span_suggestion_short_with_applicability(
3627 "try removing this `match`",
3629 Applicability::MaybeIncorrect // speculative
3634 attrs.extend(self.parse_inner_attributes()?);
3636 let mut arms: Vec<Arm> = Vec::new();
3637 while self.token != token::CloseDelim(token::Brace) {
3638 match self.parse_arm() {
3639 Ok(arm) => arms.push(arm),
3641 // Recover by skipping to the end of the block.
3643 self.recover_stmt();
3644 let span = lo.to(self.span);
3645 if self.token == token::CloseDelim(token::Brace) {
3648 return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
3654 return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
3657 crate fn parse_arm(&mut self) -> PResult<'a, Arm> {
3658 maybe_whole!(self, NtArm, |x| x);
3660 let attrs = self.parse_outer_attributes()?;
3661 // Allow a '|' before the pats (RFC 1925)
3662 self.eat(&token::BinOp(token::Or));
3663 let pats = self.parse_pats()?;
3664 let guard = if self.eat_keyword(keywords::If) {
3665 Some(Guard::If(self.parse_expr()?))
3669 let arrow_span = self.span;
3670 self.expect(&token::FatArrow)?;
3671 let arm_start_span = self.span;
3673 let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
3674 .map_err(|mut err| {
3675 err.span_label(arrow_span, "while parsing the `match` arm starting here");
3679 let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
3680 && self.token != token::CloseDelim(token::Brace);
3683 let cm = self.sess.source_map();
3684 self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
3685 .map_err(|mut err| {
3686 match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
3687 (Ok(ref expr_lines), Ok(ref arm_start_lines))
3688 if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
3689 && expr_lines.lines.len() == 2
3690 && self.token == token::FatArrow => {
3691 // We check whether there's any trailing code in the parse span,
3692 // if there isn't, we very likely have the following:
3695 // | -- - missing comma
3701 // | parsed until here as `"y" & X`
3702 err.span_suggestion_short_with_applicability(
3703 cm.next_point(arm_start_span),
3704 "missing a comma here to end this `match` arm",
3706 Applicability::MachineApplicable
3710 err.span_label(arrow_span,
3711 "while parsing the `match` arm starting here");
3717 self.eat(&token::Comma);
3728 /// Parse an expression
3730 pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
3731 self.parse_expr_res(Restrictions::empty(), None)
3734 /// Evaluate the closure with restrictions in place.
3736 /// After the closure is evaluated, restrictions are reset.
3737 fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T
3738 where F: FnOnce(&mut Self) -> T
3740 let old = self.restrictions;
3741 self.restrictions = r;
3743 self.restrictions = old;
3748 /// Parse an expression, subject to the given restrictions
3750 fn parse_expr_res(&mut self, r: Restrictions,
3751 already_parsed_attrs: Option<ThinVec<Attribute>>)
3752 -> PResult<'a, P<Expr>> {
3753 self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
3756 /// Parse the RHS of a local variable declaration (e.g., '= 14;')
3757 fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
3758 if self.eat(&token::Eq) {
3759 Ok(Some(self.parse_expr()?))
3761 Ok(Some(self.parse_expr()?))
3767 /// Parse patterns, separated by '|' s
3768 fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3769 let mut pats = Vec::new();
3771 pats.push(self.parse_top_level_pat()?);
3773 if self.token == token::OrOr {
3774 let mut err = self.struct_span_err(self.span,
3775 "unexpected token `||` after pattern");
3776 err.span_suggestion_with_applicability(
3778 "use a single `|` to specify multiple patterns",
3780 Applicability::MachineApplicable
3784 } else if self.eat(&token::BinOp(token::Or)) {
3792 // Parses a parenthesized list of patterns like
3793 // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns:
3794 // - a vector of the patterns that were parsed
3795 // - an option indicating the index of the `..` element
3796 // - a boolean indicating whether a trailing comma was present.
3797 // Trailing commas are significant because (p) and (p,) are different patterns.
3798 fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3799 self.expect(&token::OpenDelim(token::Paren))?;
3800 let result = self.parse_pat_list()?;
3801 self.expect(&token::CloseDelim(token::Paren))?;
3805 fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3806 let mut fields = Vec::new();
3807 let mut ddpos = None;
3808 let mut trailing_comma = false;
3810 if self.eat(&token::DotDot) {
3811 if ddpos.is_none() {
3812 ddpos = Some(fields.len());
3814 // Emit a friendly error, ignore `..` and continue parsing
3815 self.span_err(self.prev_span,
3816 "`..` can only be used once per tuple or tuple struct pattern");
3818 } else if !self.check(&token::CloseDelim(token::Paren)) {
3819 fields.push(self.parse_pat(None)?);
3824 trailing_comma = self.eat(&token::Comma);
3825 if !trailing_comma {
3830 if ddpos == Some(fields.len()) && trailing_comma {
3831 // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
3832 self.span_err(self.prev_span, "trailing comma is not permitted after `..`");
3835 Ok((fields, ddpos, trailing_comma))
3838 fn parse_pat_vec_elements(
3840 ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3841 let mut before = Vec::new();
3842 let mut slice = None;
3843 let mut after = Vec::new();
3844 let mut first = true;
3845 let mut before_slice = true;
3847 while self.token != token::CloseDelim(token::Bracket) {
3851 self.expect(&token::Comma)?;
3853 if self.token == token::CloseDelim(token::Bracket)
3854 && (before_slice || !after.is_empty()) {
3860 if self.eat(&token::DotDot) {
3862 if self.check(&token::Comma) ||
3863 self.check(&token::CloseDelim(token::Bracket)) {
3864 slice = Some(P(Pat {
3865 id: ast::DUMMY_NODE_ID,
3866 node: PatKind::Wild,
3867 span: self.prev_span,
3869 before_slice = false;
3875 let subpat = self.parse_pat(None)?;
3876 if before_slice && self.eat(&token::DotDot) {
3877 slice = Some(subpat);
3878 before_slice = false;
3879 } else if before_slice {
3880 before.push(subpat);
3886 Ok((before, slice, after))
3892 attrs: Vec<Attribute>
3893 ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> {
3894 // Check if a colon exists one ahead. This means we're parsing a fieldname.
3896 let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3897 // Parsing a pattern of the form "fieldname: pat"
3898 let fieldname = self.parse_field_name()?;
3900 let pat = self.parse_pat(None)?;
3902 (pat, fieldname, false)
3904 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3905 let is_box = self.eat_keyword(keywords::Box);
3906 let boxed_span = self.span;
3907 let is_ref = self.eat_keyword(keywords::Ref);
3908 let is_mut = self.eat_keyword(keywords::Mut);
3909 let fieldname = self.parse_ident()?;
3910 hi = self.prev_span;
3912 let bind_type = match (is_ref, is_mut) {
3913 (true, true) => BindingMode::ByRef(Mutability::Mutable),
3914 (true, false) => BindingMode::ByRef(Mutability::Immutable),
3915 (false, true) => BindingMode::ByValue(Mutability::Mutable),
3916 (false, false) => BindingMode::ByValue(Mutability::Immutable),
3918 let fieldpat = P(Pat {
3919 id: ast::DUMMY_NODE_ID,
3920 node: PatKind::Ident(bind_type, fieldname, None),
3921 span: boxed_span.to(hi),
3924 let subpat = if is_box {
3926 id: ast::DUMMY_NODE_ID,
3927 node: PatKind::Box(fieldpat),
3933 (subpat, fieldname, true)
3936 Ok(source_map::Spanned {
3938 node: ast::FieldPat {
3942 attrs: attrs.into(),
3947 /// Parse the fields of a struct-like pattern
3948 fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> {
3949 let mut fields = Vec::new();
3950 let mut etc = false;
3951 let mut ate_comma = true;
3952 let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
3953 let mut etc_span = None;
3955 while self.token != token::CloseDelim(token::Brace) {
3956 let attrs = self.parse_outer_attributes()?;
3959 // check that a comma comes after every field
3961 let err = self.struct_span_err(self.prev_span, "expected `,`");
3962 if let Some(mut delayed) = delayed_err {
3969 if self.check(&token::DotDot) || self.token == token::DotDotDot {
3971 let mut etc_sp = self.span;
3973 if self.token == token::DotDotDot { // Issue #46718
3974 // Accept `...` as if it were `..` to avoid further errors
3975 let mut err = self.struct_span_err(self.span,
3976 "expected field pattern, found `...`");
3977 err.span_suggestion_with_applicability(
3979 "to omit remaining fields, use one fewer `.`",
3981 Applicability::MachineApplicable
3985 self.bump(); // `..` || `...`
3987 if self.token == token::CloseDelim(token::Brace) {
3988 etc_span = Some(etc_sp);
3991 let token_str = self.this_token_descr();
3992 let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
3994 err.span_label(self.span, "expected `}`");
3995 let mut comma_sp = None;
3996 if self.token == token::Comma { // Issue #49257
3997 etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span));
3998 err.span_label(etc_sp,
3999 "`..` must be at the end and cannot have a trailing comma");
4000 comma_sp = Some(self.span);
4005 etc_span = Some(etc_sp.until(self.span));
4006 if self.token == token::CloseDelim(token::Brace) {
4007 // If the struct looks otherwise well formed, recover and continue.
4008 if let Some(sp) = comma_sp {
4009 err.span_suggestion_short_with_applicability(
4011 "remove this comma",
4013 Applicability::MachineApplicable,
4018 } else if self.token.is_ident() && ate_comma {
4019 // Accept fields coming after `..,`.
4020 // This way we avoid "pattern missing fields" errors afterwards.
4021 // We delay this error until the end in order to have a span for a
4023 if let Some(mut delayed_err) = delayed_err {
4027 delayed_err = Some(err);
4030 if let Some(mut err) = delayed_err {
4037 fields.push(match self.parse_pat_field(lo, attrs) {
4040 if let Some(mut delayed_err) = delayed_err {
4046 ate_comma = self.eat(&token::Comma);
4049 if let Some(mut err) = delayed_err {
4050 if let Some(etc_span) = etc_span {
4051 err.multipart_suggestion(
4052 "move the `..` to the end of the field list",
4054 (etc_span, String::new()),
4055 (self.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
4061 return Ok((fields, etc));
4064 fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
4065 if self.token.is_path_start() {
4067 let (qself, path) = if self.eat_lt() {
4068 // Parse a qualified path
4069 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4072 // Parse an unqualified path
4073 (None, self.parse_path(PathStyle::Expr)?)
4075 let hi = self.prev_span;
4076 Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
4078 self.parse_literal_maybe_minus()
4082 // helper function to decide whether to parse as ident binding or to try to do
4083 // something more complex like range patterns
4084 fn parse_as_ident(&mut self) -> bool {
4085 self.look_ahead(1, |t| match *t {
4086 token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
4087 token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false),
4088 // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the
4089 // range pattern branch
4090 token::DotDot => None,
4092 }).unwrap_or_else(|| self.look_ahead(2, |t| match *t {
4093 token::Comma | token::CloseDelim(token::Bracket) => true,
4098 /// A wrapper around `parse_pat` with some special error handling for the
4099 /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
4100 /// to subpatterns within such).
4101 fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
4102 let pat = self.parse_pat(None)?;
4103 if self.token == token::Comma {
4104 // An unexpected comma after a top-level pattern is a clue that the
4105 // user (perhaps more accustomed to some other language) forgot the
4106 // parentheses in what should have been a tuple pattern; return a
4107 // suggestion-enhanced error here rather than choking on the comma
4109 let comma_span = self.span;
4111 if let Err(mut err) = self.parse_pat_list() {
4112 // We didn't expect this to work anyway; we just wanted
4113 // to advance to the end of the comma-sequence so we know
4114 // the span to suggest parenthesizing
4117 let seq_span = pat.span.to(self.prev_span);
4118 let mut err = self.struct_span_err(comma_span,
4119 "unexpected `,` in pattern");
4120 if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) {
4121 err.span_suggestion_with_applicability(
4123 "try adding parentheses",
4124 format!("({})", seq_snippet),
4125 Applicability::MachineApplicable
4133 /// Parse a pattern.
4134 pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
4135 self.parse_pat_with_range_pat(true, expected)
4138 /// Parse a pattern, with a setting whether modern range patterns e.g., `a..=b`, `a..b` are
4140 fn parse_pat_with_range_pat(
4142 allow_range_pat: bool,
4143 expected: Option<&'static str>,
4144 ) -> PResult<'a, P<Pat>> {
4145 maybe_whole!(self, NtPat, |x| x);
4150 token::BinOp(token::And) | token::AndAnd => {
4151 // Parse &pat / &mut pat
4153 let mutbl = self.parse_mutability();
4154 if let token::Lifetime(ident) = self.token {
4155 let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern",
4157 err.span_label(self.span, "unexpected lifetime");
4160 let subpat = self.parse_pat_with_range_pat(false, expected)?;
4161 pat = PatKind::Ref(subpat, mutbl);
4163 token::OpenDelim(token::Paren) => {
4164 // Parse (pat,pat,pat,...) as tuple pattern
4165 let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?;
4166 pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma {
4167 PatKind::Paren(fields.into_iter().nth(0).unwrap())
4169 PatKind::Tuple(fields, ddpos)
4172 token::OpenDelim(token::Bracket) => {
4173 // Parse [pat,pat,...] as slice pattern
4175 let (before, slice, after) = self.parse_pat_vec_elements()?;
4176 self.expect(&token::CloseDelim(token::Bracket))?;
4177 pat = PatKind::Slice(before, slice, after);
4179 // At this point, token != &, &&, (, [
4180 _ => if self.eat_keyword(keywords::Underscore) {
4182 pat = PatKind::Wild;
4183 } else if self.eat_keyword(keywords::Mut) {
4184 // Parse mut ident @ pat / mut ref ident @ pat
4185 let mutref_span = self.prev_span.to(self.span);
4186 let binding_mode = if self.eat_keyword(keywords::Ref) {
4188 .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
4189 .span_suggestion_with_applicability(
4191 "try switching the order",
4193 Applicability::MachineApplicable
4195 BindingMode::ByRef(Mutability::Mutable)
4197 BindingMode::ByValue(Mutability::Mutable)
4199 pat = self.parse_pat_ident(binding_mode)?;
4200 } else if self.eat_keyword(keywords::Ref) {
4201 // Parse ref ident @ pat / ref mut ident @ pat
4202 let mutbl = self.parse_mutability();
4203 pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
4204 } else if self.eat_keyword(keywords::Box) {
4206 let subpat = self.parse_pat_with_range_pat(false, None)?;
4207 pat = PatKind::Box(subpat);
4208 } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
4209 self.parse_as_ident() {
4210 // Parse ident @ pat
4211 // This can give false positives and parse nullary enums,
4212 // they are dealt with later in resolve
4213 let binding_mode = BindingMode::ByValue(Mutability::Immutable);
4214 pat = self.parse_pat_ident(binding_mode)?;
4215 } else if self.token.is_path_start() {
4216 // Parse pattern starting with a path
4217 let (qself, path) = if self.eat_lt() {
4218 // Parse a qualified path
4219 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4222 // Parse an unqualified path
4223 (None, self.parse_path(PathStyle::Expr)?)
4226 token::Not if qself.is_none() => {
4227 // Parse macro invocation
4229 let (delim, tts) = self.expect_delimited_token_tree()?;
4230 let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim });
4231 pat = PatKind::Mac(mac);
4233 token::DotDotDot | token::DotDotEq | token::DotDot => {
4234 let end_kind = match self.token {
4235 token::DotDot => RangeEnd::Excluded,
4236 token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot),
4237 token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq),
4238 _ => panic!("can only parse `..`/`...`/`..=` for ranges \
4241 let op_span = self.span;
4243 let span = lo.to(self.prev_span);
4244 let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
4246 let end = self.parse_pat_range_end()?;
4247 let op = Spanned { span: op_span, node: end_kind };
4248 pat = PatKind::Range(begin, end, op);
4250 token::OpenDelim(token::Brace) => {
4251 if qself.is_some() {
4252 let msg = "unexpected `{` after qualified path";
4253 let mut err = self.fatal(msg);
4254 err.span_label(self.span, msg);
4257 // Parse struct pattern
4259 let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
4261 self.recover_stmt();
4265 pat = PatKind::Struct(path, fields, etc);
4267 token::OpenDelim(token::Paren) => {
4268 if qself.is_some() {
4269 let msg = "unexpected `(` after qualified path";
4270 let mut err = self.fatal(msg);
4271 err.span_label(self.span, msg);
4274 // Parse tuple struct or enum pattern
4275 let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?;
4276 pat = PatKind::TupleStruct(path, fields, ddpos)
4278 _ => pat = PatKind::Path(qself, path),
4281 // Try to parse everything else as literal with optional minus
4282 match self.parse_literal_maybe_minus() {
4284 let op_span = self.span;
4285 if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
4286 self.check(&token::DotDotDot) {
4287 let end_kind = if self.eat(&token::DotDotDot) {
4288 RangeEnd::Included(RangeSyntax::DotDotDot)
4289 } else if self.eat(&token::DotDotEq) {
4290 RangeEnd::Included(RangeSyntax::DotDotEq)
4291 } else if self.eat(&token::DotDot) {
4294 panic!("impossible case: we already matched \
4295 on a range-operator token")
4297 let end = self.parse_pat_range_end()?;
4298 let op = Spanned { span: op_span, node: end_kind };
4299 pat = PatKind::Range(begin, end, op);
4301 pat = PatKind::Lit(begin);
4305 self.cancel(&mut err);
4306 let expected = expected.unwrap_or("pattern");
4308 "expected {}, found {}",
4310 self.this_token_descr(),
4312 let mut err = self.fatal(&msg);
4313 err.span_label(self.span, format!("expected {}", expected));
4320 let pat = Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID };
4321 let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
4323 if !allow_range_pat {
4326 _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
4328 PatKind::Range(..) => {
4329 let mut err = self.struct_span_err(
4331 "the range pattern here has ambiguous interpretation",
4333 err.span_suggestion_with_applicability(
4335 "add parentheses to clarify the precedence",
4336 format!("({})", pprust::pat_to_string(&pat)),
4337 // "ambiguous interpretation" implies that we have to be guessing
4338 Applicability::MaybeIncorrect
4349 /// Parse ident or ident @ pat
4350 /// used by the copy foo and ref foo patterns to give a good
4351 /// error message when parsing mistakes like ref foo(a,b)
4352 fn parse_pat_ident(&mut self,
4353 binding_mode: ast::BindingMode)
4354 -> PResult<'a, PatKind> {
4355 let ident = self.parse_ident()?;
4356 let sub = if self.eat(&token::At) {
4357 Some(self.parse_pat(Some("binding pattern"))?)
4362 // just to be friendly, if they write something like
4364 // we end up here with ( as the current token. This shortly
4365 // leads to a parse error. Note that if there is no explicit
4366 // binding mode then we do not end up here, because the lookahead
4367 // will direct us over to parse_enum_variant()
4368 if self.token == token::OpenDelim(token::Paren) {
4369 return Err(self.span_fatal(
4371 "expected identifier, found enum pattern"))
4374 Ok(PatKind::Ident(binding_mode, ident, sub))
4377 /// Parse a local variable declaration
4378 fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
4379 let lo = self.prev_span;
4380 let pat = self.parse_top_level_pat()?;
4382 let (err, ty) = if self.eat(&token::Colon) {
4383 // Save the state of the parser before parsing type normally, in case there is a `:`
4384 // instead of an `=` typo.
4385 let parser_snapshot_before_type = self.clone();
4386 let colon_sp = self.prev_span;
4387 match self.parse_ty() {
4388 Ok(ty) => (None, Some(ty)),
4390 // Rewind to before attempting to parse the type and continue parsing
4391 let parser_snapshot_after_type = self.clone();
4392 mem::replace(self, parser_snapshot_before_type);
4394 let snippet = self.sess.source_map().span_to_snippet(pat.span).unwrap();
4395 err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
4396 (Some((parser_snapshot_after_type, colon_sp, err)), None)
4402 let init = match (self.parse_initializer(err.is_some()), err) {
4403 (Ok(init), None) => { // init parsed, ty parsed
4406 (Ok(init), Some((_, colon_sp, mut err))) => { // init parsed, ty error
4407 // Could parse the type as if it were the initializer, it is likely there was a
4408 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
4409 err.span_suggestion_short_with_applicability(
4411 "use `=` if you meant to assign",
4413 Applicability::MachineApplicable
4416 // As this was parsed successfully, continue as if the code has been fixed for the
4417 // rest of the file. It will still fail due to the emitted error, but we avoid
4421 (Err(mut init_err), Some((snapshot, _, ty_err))) => { // init error, ty error
4423 // Couldn't parse the type nor the initializer, only raise the type error and
4424 // return to the parser state before parsing the type as the initializer.
4425 // let x: <parse_error>;
4426 mem::replace(self, snapshot);
4429 (Err(err), None) => { // init error, ty parsed
4430 // Couldn't parse the initializer and we're not attempting to recover a failed
4431 // parse of the type, return the error.
4435 let hi = if self.token == token::Semi {
4444 id: ast::DUMMY_NODE_ID,
4450 /// Parse a structure field
4451 fn parse_name_and_ty(&mut self,
4454 attrs: Vec<Attribute>)
4455 -> PResult<'a, StructField> {
4456 let name = self.parse_ident()?;
4457 self.expect(&token::Colon)?;
4458 let ty = self.parse_ty()?;
4460 span: lo.to(self.prev_span),
4463 id: ast::DUMMY_NODE_ID,
4469 /// Emit an expected item after attributes error.
4470 fn expected_item_err(&self, attrs: &[Attribute]) {
4471 let message = match attrs.last() {
4472 Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
4473 _ => "expected item after attributes",
4476 self.span_err(self.prev_span, message);
4479 /// Parse a statement. This stops just before trailing semicolons on everything but items.
4480 /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
4481 pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
4482 Ok(self.parse_stmt_(true))
4485 // Eat tokens until we can be relatively sure we reached the end of the
4486 // statement. This is something of a best-effort heuristic.
4488 // We terminate when we find an unmatched `}` (without consuming it).
4489 fn recover_stmt(&mut self) {
4490 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
4493 // If `break_on_semi` is `Break`, then we will stop consuming tokens after
4494 // finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
4495 // approximate - it can mean we break too early due to macros, but that
4496 // should only lead to sub-optimal recovery, not inaccurate parsing).
4498 // If `break_on_block` is `Break`, then we will stop consuming tokens
4499 // after finding (and consuming) a brace-delimited block.
4500 fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) {
4501 let mut brace_depth = 0;
4502 let mut bracket_depth = 0;
4503 let mut in_block = false;
4504 debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
4505 break_on_semi, break_on_block);
4507 debug!("recover_stmt_ loop {:?}", self.token);
4509 token::OpenDelim(token::DelimToken::Brace) => {
4512 if break_on_block == BlockMode::Break &&
4514 bracket_depth == 0 {
4518 token::OpenDelim(token::DelimToken::Bracket) => {
4522 token::CloseDelim(token::DelimToken::Brace) => {
4523 if brace_depth == 0 {
4524 debug!("recover_stmt_ return - close delim {:?}", self.token);
4529 if in_block && bracket_depth == 0 && brace_depth == 0 {
4530 debug!("recover_stmt_ return - block end {:?}", self.token);
4534 token::CloseDelim(token::DelimToken::Bracket) => {
4536 if bracket_depth < 0 {
4542 debug!("recover_stmt_ return - Eof");
4547 if break_on_semi == SemiColonMode::Break &&
4549 bracket_depth == 0 {
4550 debug!("recover_stmt_ return - Semi");
4561 fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
4562 self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
4564 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4569 fn is_async_block(&mut self) -> bool {
4570 self.token.is_keyword(keywords::Async) &&
4573 self.look_ahead(1, |t| t.is_keyword(keywords::Move)) &&
4574 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
4576 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
4581 fn is_do_catch_block(&mut self) -> bool {
4582 self.token.is_keyword(keywords::Do) &&
4583 self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) &&
4584 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
4585 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4588 fn is_try_block(&mut self) -> bool {
4589 self.token.is_keyword(keywords::Try) &&
4590 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
4591 self.span.rust_2018() &&
4592 // prevent `while try {} {}`, `if try {} {} else {}`, etc.
4593 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4596 fn is_union_item(&self) -> bool {
4597 self.token.is_keyword(keywords::Union) &&
4598 self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
4601 fn is_crate_vis(&self) -> bool {
4602 self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
4605 fn is_extern_non_path(&self) -> bool {
4606 self.token.is_keyword(keywords::Extern) && self.look_ahead(1, |t| t != &token::ModSep)
4609 fn is_existential_type_decl(&self) -> bool {
4610 self.token.is_keyword(keywords::Existential) &&
4611 self.look_ahead(1, |t| t.is_keyword(keywords::Type))
4614 fn is_auto_trait_item(&mut self) -> bool {
4616 (self.token.is_keyword(keywords::Auto)
4617 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
4618 || // unsafe auto trait
4619 (self.token.is_keyword(keywords::Unsafe) &&
4620 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) &&
4621 self.look_ahead(2, |t| t.is_keyword(keywords::Trait)))
4624 fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span)
4625 -> PResult<'a, Option<P<Item>>> {
4626 let token_lo = self.span;
4627 let (ident, def) = match self.token {
4628 token::Ident(ident, false) if ident.name == keywords::Macro.name() => {
4630 let ident = self.parse_ident()?;
4631 let tokens = if self.check(&token::OpenDelim(token::Brace)) {
4632 match self.parse_token_tree() {
4633 TokenTree::Delimited(_, _, tts) => tts.stream(),
4634 _ => unreachable!(),
4636 } else if self.check(&token::OpenDelim(token::Paren)) {
4637 let args = self.parse_token_tree();
4638 let body = if self.check(&token::OpenDelim(token::Brace)) {
4639 self.parse_token_tree()
4644 TokenStream::new(vec![
4646 TokenTree::Token(token_lo.to(self.prev_span), token::FatArrow).into(),
4654 (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
4656 token::Ident(ident, _) if ident.name == "macro_rules" &&
4657 self.look_ahead(1, |t| *t == token::Not) => {
4658 let prev_span = self.prev_span;
4659 self.complain_if_pub_macro(&vis.node, prev_span);
4663 let ident = self.parse_ident()?;
4664 let (delim, tokens) = self.expect_delimited_token_tree()?;
4665 if delim != MacDelimiter::Brace {
4666 if !self.eat(&token::Semi) {
4667 let msg = "macros that expand to items must either \
4668 be surrounded with braces or followed by a semicolon";
4669 self.span_err(self.prev_span, msg);
4673 (ident, ast::MacroDef { tokens: tokens, legacy: true })
4675 _ => return Ok(None),
4678 let span = lo.to(self.prev_span);
4679 Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
4682 fn parse_stmt_without_recovery(&mut self,
4683 macro_legacy_warnings: bool)
4684 -> PResult<'a, Option<Stmt>> {
4685 maybe_whole!(self, NtStmt, |x| Some(x));
4687 let attrs = self.parse_outer_attributes()?;
4690 Ok(Some(if self.eat_keyword(keywords::Let) {
4692 id: ast::DUMMY_NODE_ID,
4693 node: StmtKind::Local(self.parse_local(attrs.into())?),
4694 span: lo.to(self.prev_span),
4696 } else if let Some(macro_def) = self.eat_macro_def(
4698 &source_map::respan(lo, VisibilityKind::Inherited),
4702 id: ast::DUMMY_NODE_ID,
4703 node: StmtKind::Item(macro_def),
4704 span: lo.to(self.prev_span),
4706 // Starts like a simple path, being careful to avoid contextual keywords
4707 // such as a union items, item with `crate` visibility or auto trait items.
4708 // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
4709 // like a path (1 token), but it fact not a path.
4710 // `union::b::c` - path, `union U { ... }` - not a path.
4711 // `crate::b::c` - path, `crate struct S;` - not a path.
4712 // `extern::b::c` - path, `extern crate c;` - not a path.
4713 } else if self.token.is_path_start() &&
4714 !self.token.is_qpath_start() &&
4715 !self.is_union_item() &&
4716 !self.is_crate_vis() &&
4717 !self.is_extern_non_path() &&
4718 !self.is_existential_type_decl() &&
4719 !self.is_auto_trait_item() {
4720 let pth = self.parse_path(PathStyle::Expr)?;
4722 if !self.eat(&token::Not) {
4723 let expr = if self.check(&token::OpenDelim(token::Brace)) {
4724 self.parse_struct_expr(lo, pth, ThinVec::new())?
4726 let hi = self.prev_span;
4727 self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), ThinVec::new())
4730 let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
4731 let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
4732 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
4735 return Ok(Some(Stmt {
4736 id: ast::DUMMY_NODE_ID,
4737 node: StmtKind::Expr(expr),
4738 span: lo.to(self.prev_span),
4742 // it's a macro invocation
4743 let id = match self.token {
4744 token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier
4745 _ => self.parse_ident()?,
4748 // check that we're pointing at delimiters (need to check
4749 // again after the `if`, because of `parse_ident`
4750 // consuming more tokens).
4752 token::OpenDelim(_) => {}
4754 // we only expect an ident if we didn't parse one
4756 let ident_str = if id.name == keywords::Invalid.name() {
4761 let tok_str = self.this_token_descr();
4762 let mut err = self.fatal(&format!("expected {}`(` or `{{`, found {}",
4765 err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str));
4770 let (delim, tts) = self.expect_delimited_token_tree()?;
4771 let hi = self.prev_span;
4773 let style = if delim == MacDelimiter::Brace {
4774 MacStmtStyle::Braces
4776 MacStmtStyle::NoBraces
4779 if id.name == keywords::Invalid.name() {
4780 let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim });
4781 let node = if delim == MacDelimiter::Brace ||
4782 self.token == token::Semi || self.token == token::Eof {
4783 StmtKind::Mac(P((mac, style, attrs.into())))
4785 // We used to incorrectly stop parsing macro-expanded statements here.
4786 // If the next token will be an error anyway but could have parsed with the
4787 // earlier behavior, stop parsing here and emit a warning to avoid breakage.
4788 else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token {
4789 // These can continue an expression, so we can't stop parsing and warn.
4790 token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
4791 token::BinOp(token::Minus) | token::BinOp(token::Star) |
4792 token::BinOp(token::And) | token::BinOp(token::Or) |
4793 token::AndAnd | token::OrOr |
4794 token::DotDot | token::DotDotDot | token::DotDotEq => false,
4797 self.warn_missing_semicolon();
4798 StmtKind::Mac(P((mac, style, attrs.into())))
4800 let e = self.mk_mac_expr(lo.to(hi), mac.node, ThinVec::new());
4801 let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
4802 let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
4806 id: ast::DUMMY_NODE_ID,
4811 // if it has a special ident, it's definitely an item
4813 // Require a semicolon or braces.
4814 if style != MacStmtStyle::Braces {
4815 if !self.eat(&token::Semi) {
4816 self.span_err(self.prev_span,
4817 "macros that expand to items must \
4818 either be surrounded with braces or \
4819 followed by a semicolon");
4822 let span = lo.to(hi);
4824 id: ast::DUMMY_NODE_ID,
4826 node: StmtKind::Item({
4828 span, id /*id is good here*/,
4829 ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })),
4830 respan(lo, VisibilityKind::Inherited),
4836 // FIXME: Bad copy of attrs
4837 let old_directory_ownership =
4838 mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
4839 let item = self.parse_item_(attrs.clone(), false, true)?;
4840 self.directory.ownership = old_directory_ownership;
4844 id: ast::DUMMY_NODE_ID,
4845 span: lo.to(i.span),
4846 node: StmtKind::Item(i),
4849 let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
4850 if !attrs.is_empty() {
4851 if s.prev_token_kind == PrevTokenKind::DocComment {
4852 s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
4853 } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
4854 s.span_err(s.span, "expected statement after outer attribute");
4859 // Do not attempt to parse an expression if we're done here.
4860 if self.token == token::Semi {
4861 unused_attrs(&attrs, self);
4866 if self.token == token::CloseDelim(token::Brace) {
4867 unused_attrs(&attrs, self);
4871 // Remainder are line-expr stmts.
4872 let e = self.parse_expr_res(
4873 Restrictions::STMT_EXPR, Some(attrs.into()))?;
4875 id: ast::DUMMY_NODE_ID,
4876 span: lo.to(e.span),
4877 node: StmtKind::Expr(e),
4884 /// Is this expression a successfully-parsed statement?
4885 fn expr_is_complete(&mut self, e: &Expr) -> bool {
4886 self.restrictions.contains(Restrictions::STMT_EXPR) &&
4887 !classify::expr_requires_semi_to_be_stmt(e)
4890 /// Parse a block. No inner attrs are allowed.
4891 pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
4892 maybe_whole!(self, NtBlock, |x| x);
4896 if !self.eat(&token::OpenDelim(token::Brace)) {
4898 let tok = self.this_token_descr();
4899 let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok));
4900 let do_not_suggest_help =
4901 self.token.is_keyword(keywords::In) || self.token == token::Colon;
4903 if self.token.is_ident_named("and") {
4904 e.span_suggestion_short_with_applicability(
4906 "use `&&` instead of `and` for the boolean operator",
4908 Applicability::MaybeIncorrect,
4911 if self.token.is_ident_named("or") {
4912 e.span_suggestion_short_with_applicability(
4914 "use `||` instead of `or` for the boolean operator",
4916 Applicability::MaybeIncorrect,
4920 // Check to see if the user has written something like
4925 // Which is valid in other languages, but not Rust.
4926 match self.parse_stmt_without_recovery(false) {
4928 if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
4929 || do_not_suggest_help {
4930 // if the next token is an open brace (e.g., `if a b {`), the place-
4931 // inside-a-block suggestion would be more likely wrong than right
4932 e.span_label(sp, "expected `{`");
4935 let mut stmt_span = stmt.span;
4936 // expand the span to include the semicolon, if it exists
4937 if self.eat(&token::Semi) {
4938 stmt_span = stmt_span.with_hi(self.prev_span.hi());
4940 let sugg = pprust::to_string(|s| {
4941 use print::pprust::{PrintState, INDENT_UNIT};
4942 s.ibox(INDENT_UNIT)?;
4944 s.print_stmt(&stmt)?;
4945 s.bclose_maybe_open(stmt.span, INDENT_UNIT, false)
4947 e.span_suggestion_with_applicability(
4949 "try placing this code inside a block",
4951 // speculative, has been misleading in the past (closed Issue #46836)
4952 Applicability::MaybeIncorrect
4956 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4957 self.cancel(&mut e);
4961 e.span_label(sp, "expected `{`");
4965 self.parse_block_tail(lo, BlockCheckMode::Default)
4968 /// Parse a block. Inner attrs are allowed.
4969 fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
4970 maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
4973 self.expect(&token::OpenDelim(token::Brace))?;
4974 Ok((self.parse_inner_attributes()?,
4975 self.parse_block_tail(lo, BlockCheckMode::Default)?))
4978 /// Parse the rest of a block expression or function body
4979 /// Precondition: already parsed the '{'.
4980 fn parse_block_tail(&mut self, lo: Span, s: BlockCheckMode) -> PResult<'a, P<Block>> {
4981 let mut stmts = vec![];
4982 while !self.eat(&token::CloseDelim(token::Brace)) {
4983 let stmt = match self.parse_full_stmt(false) {
4986 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
4988 id: ast::DUMMY_NODE_ID,
4989 node: StmtKind::Expr(DummyResult::raw_expr(self.span, true)),
4995 if let Some(stmt) = stmt {
4997 } else if self.token == token::Eof {
5000 // Found only `;` or `}`.
5006 id: ast::DUMMY_NODE_ID,
5008 span: lo.to(self.prev_span),
5012 /// Parse a statement, including the trailing semicolon.
5013 crate fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
5014 // skip looking for a trailing semicolon when we have an interpolated statement
5015 maybe_whole!(self, NtStmt, |x| Some(x));
5017 let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
5019 None => return Ok(None),
5023 StmtKind::Expr(ref expr) if self.token != token::Eof => {
5024 // expression without semicolon
5025 if classify::expr_requires_semi_to_be_stmt(expr) {
5026 // Just check for errors and recover; do not eat semicolon yet.
5028 self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
5031 self.recover_stmt();
5035 StmtKind::Local(..) => {
5036 // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
5037 if macro_legacy_warnings && self.token != token::Semi {
5038 self.warn_missing_semicolon();
5040 self.expect_one_of(&[], &[token::Semi])?;
5046 if self.eat(&token::Semi) {
5047 stmt = stmt.add_trailing_semicolon();
5050 stmt.span = stmt.span.with_hi(self.prev_span.hi());
5054 fn warn_missing_semicolon(&self) {
5055 self.diagnostic().struct_span_warn(self.span, {
5056 &format!("expected `;`, found {}", self.this_token_descr())
5058 "This was erroneously allowed and will become a hard error in a future release"
5062 fn err_dotdotdot_syntax(&self, span: Span) {
5063 self.diagnostic().struct_span_err(span, {
5064 "unexpected token: `...`"
5065 }).span_suggestion_with_applicability(
5066 span, "use `..` for an exclusive range", "..".to_owned(),
5067 Applicability::MaybeIncorrect
5068 ).span_suggestion_with_applicability(
5069 span, "or `..=` for an inclusive range", "..=".to_owned(),
5070 Applicability::MaybeIncorrect
5074 // Parse bounds of a type parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5075 // BOUND = TY_BOUND | LT_BOUND
5076 // LT_BOUND = LIFETIME (e.g., `'a`)
5077 // TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
5078 // TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
5079 fn parse_generic_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, GenericBounds> {
5080 let mut bounds = Vec::new();
5082 // This needs to be synchronized with `Token::can_begin_bound`.
5083 let is_bound_start = self.check_path() || self.check_lifetime() ||
5084 self.check(&token::Question) ||
5085 self.check_keyword(keywords::For) ||
5086 self.check(&token::OpenDelim(token::Paren));
5089 let has_parens = self.eat(&token::OpenDelim(token::Paren));
5090 let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
5091 if self.token.is_lifetime() {
5092 if let Some(question_span) = question {
5093 self.span_err(question_span,
5094 "`?` may only modify trait bounds, not lifetime bounds");
5096 bounds.push(GenericBound::Outlives(self.expect_lifetime()));
5098 self.expect(&token::CloseDelim(token::Paren))?;
5099 self.span_err(self.prev_span,
5100 "parenthesized lifetime bounds are not supported");
5103 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5104 let path = self.parse_path(PathStyle::Type)?;
5106 self.expect(&token::CloseDelim(token::Paren))?;
5108 let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span));
5109 let modifier = if question.is_some() {
5110 TraitBoundModifier::Maybe
5112 TraitBoundModifier::None
5114 bounds.push(GenericBound::Trait(poly_trait, modifier));
5120 if !allow_plus || !self.eat_plus() {
5128 fn parse_generic_bounds(&mut self) -> PResult<'a, GenericBounds> {
5129 self.parse_generic_bounds_common(true)
5132 // Parse bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5133 // BOUND = LT_BOUND (e.g., `'a`)
5134 fn parse_lt_param_bounds(&mut self) -> GenericBounds {
5135 let mut lifetimes = Vec::new();
5136 while self.check_lifetime() {
5137 lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
5139 if !self.eat_plus() {
5146 /// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
5147 fn parse_ty_param(&mut self,
5148 preceding_attrs: Vec<Attribute>)
5149 -> PResult<'a, GenericParam> {
5150 let ident = self.parse_ident()?;
5152 // Parse optional colon and param bounds.
5153 let bounds = if self.eat(&token::Colon) {
5154 self.parse_generic_bounds()?
5159 let default = if self.eat(&token::Eq) {
5160 Some(self.parse_ty()?)
5167 id: ast::DUMMY_NODE_ID,
5168 attrs: preceding_attrs.into(),
5170 kind: GenericParamKind::Type {
5176 /// Parses the following grammar:
5177 /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
5178 fn parse_trait_item_assoc_ty(&mut self)
5179 -> PResult<'a, (Ident, TraitItemKind, ast::Generics)> {
5180 let ident = self.parse_ident()?;
5181 let mut generics = self.parse_generics()?;
5183 // Parse optional colon and param bounds.
5184 let bounds = if self.eat(&token::Colon) {
5185 self.parse_generic_bounds()?
5189 generics.where_clause = self.parse_where_clause()?;
5191 let default = if self.eat(&token::Eq) {
5192 Some(self.parse_ty()?)
5196 self.expect(&token::Semi)?;
5198 Ok((ident, TraitItemKind::Type(bounds, default), generics))
5201 /// Parses (possibly empty) list of lifetime and type parameters, possibly including
5202 /// trailing comma and erroneous trailing attributes.
5203 crate fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
5204 let mut lifetimes = Vec::new();
5205 let mut params = Vec::new();
5206 let mut seen_ty_param: Option<Span> = None;
5207 let mut last_comma_span = None;
5208 let mut bad_lifetime_pos = vec![];
5209 let mut suggestions = vec![];
5211 let attrs = self.parse_outer_attributes()?;
5212 if self.check_lifetime() {
5213 let lifetime = self.expect_lifetime();
5214 // Parse lifetime parameter.
5215 let bounds = if self.eat(&token::Colon) {
5216 self.parse_lt_param_bounds()
5220 lifetimes.push(ast::GenericParam {
5221 ident: lifetime.ident,
5223 attrs: attrs.into(),
5225 kind: ast::GenericParamKind::Lifetime,
5227 if let Some(sp) = seen_ty_param {
5228 let param_span = self.prev_span;
5229 let ate_comma = self.eat(&token::Comma);
5230 let remove_sp = if ate_comma {
5231 param_span.until(self.span)
5233 last_comma_span.unwrap_or(param_span).to(param_span)
5235 bad_lifetime_pos.push(param_span);
5237 if let Ok(snippet) = self.sess.source_map().span_to_snippet(param_span) {
5238 suggestions.push((remove_sp, String::new()));
5239 suggestions.push((sp.shrink_to_lo(), format!("{}, ", snippet)));
5242 last_comma_span = Some(self.prev_span);
5246 } else if self.check_ident() {
5247 // Parse type parameter.
5248 params.push(self.parse_ty_param(attrs)?);
5249 if seen_ty_param.is_none() {
5250 seen_ty_param = Some(self.prev_span);
5253 // Check for trailing attributes and stop parsing.
5254 if !attrs.is_empty() {
5255 let param_kind = if seen_ty_param.is_some() { "type" } else { "lifetime" };
5256 self.span_err(attrs[0].span,
5257 &format!("trailing attribute after {} parameters", param_kind));
5262 if !self.eat(&token::Comma) {
5265 last_comma_span = Some(self.prev_span);
5267 if !bad_lifetime_pos.is_empty() {
5268 let mut err = self.struct_span_err(
5270 "lifetime parameters must be declared prior to type parameters",
5272 if !suggestions.is_empty() {
5273 err.multipart_suggestion_with_applicability(
5274 "move the lifetime parameter prior to the first type parameter",
5276 Applicability::MachineApplicable,
5281 lifetimes.extend(params); // ensure the correct order of lifetimes and type params
5285 /// Parse a set of optional generic type parameter declarations. Where
5286 /// clauses are not parsed here, and must be added later via
5287 /// `parse_where_clause()`.
5289 /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
5290 /// | ( < lifetimes , typaramseq ( , )? > )
5291 /// where typaramseq = ( typaram ) | ( typaram , typaramseq )
5292 fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
5293 maybe_whole!(self, NtGenerics, |x| x);
5295 let span_lo = self.span;
5297 let params = self.parse_generic_params()?;
5301 where_clause: WhereClause {
5302 id: ast::DUMMY_NODE_ID,
5303 predicates: Vec::new(),
5304 span: syntax_pos::DUMMY_SP,
5306 span: span_lo.to(self.prev_span),
5309 Ok(ast::Generics::default())
5313 /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
5314 /// possibly including trailing comma.
5315 fn parse_generic_args(&mut self)
5316 -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
5317 let mut args = Vec::new();
5318 let mut bindings = Vec::new();
5319 let mut seen_type = false;
5320 let mut seen_binding = false;
5322 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5323 // Parse lifetime argument.
5324 args.push(GenericArg::Lifetime(self.expect_lifetime()));
5325 if seen_type || seen_binding {
5326 self.span_err(self.prev_span,
5327 "lifetime parameters must be declared prior to type parameters");
5329 } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
5330 // Parse associated type binding.
5332 let ident = self.parse_ident()?;
5334 let ty = self.parse_ty()?;
5335 bindings.push(TypeBinding {
5336 id: ast::DUMMY_NODE_ID,
5339 span: lo.to(self.prev_span),
5341 seen_binding = true;
5342 } else if self.check_type() {
5343 // Parse type argument.
5344 let ty_param = self.parse_ty()?;
5346 self.span_err(ty_param.span,
5347 "type parameters must be declared prior to associated type bindings");
5349 args.push(GenericArg::Type(ty_param));
5355 if !self.eat(&token::Comma) {
5359 Ok((args, bindings))
5362 /// Parses an optional `where` clause and places it in `generics`.
5364 /// ```ignore (only-for-syntax-highlight)
5365 /// where T : Trait<U, V> + 'b, 'a : 'b
5367 fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
5368 maybe_whole!(self, NtWhereClause, |x| x);
5370 let mut where_clause = WhereClause {
5371 id: ast::DUMMY_NODE_ID,
5372 predicates: Vec::new(),
5373 span: syntax_pos::DUMMY_SP,
5376 if !self.eat_keyword(keywords::Where) {
5377 return Ok(where_clause);
5379 let lo = self.prev_span;
5381 // We are considering adding generics to the `where` keyword as an alternative higher-rank
5382 // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
5383 // change we parse those generics now, but report an error.
5384 if self.choose_generics_over_qpath() {
5385 let generics = self.parse_generics()?;
5386 self.span_err(generics.span,
5387 "generic parameters on `where` clauses are reserved for future use");
5392 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5393 let lifetime = self.expect_lifetime();
5394 // Bounds starting with a colon are mandatory, but possibly empty.
5395 self.expect(&token::Colon)?;
5396 let bounds = self.parse_lt_param_bounds();
5397 where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
5398 ast::WhereRegionPredicate {
5399 span: lo.to(self.prev_span),
5404 } else if self.check_type() {
5405 // Parse optional `for<'a, 'b>`.
5406 // This `for` is parsed greedily and applies to the whole predicate,
5407 // the bounded type can have its own `for` applying only to it.
5408 // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/>
5409 // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/>
5410 // Example 3: for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /*ok*/, 'b /*not ok*/>
5411 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5413 // Parse type with mandatory colon and (possibly empty) bounds,
5414 // or with mandatory equality sign and the second type.
5415 let ty = self.parse_ty()?;
5416 if self.eat(&token::Colon) {
5417 let bounds = self.parse_generic_bounds()?;
5418 where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
5419 ast::WhereBoundPredicate {
5420 span: lo.to(self.prev_span),
5421 bound_generic_params: lifetime_defs,
5426 // FIXME: Decide what should be used here, `=` or `==`.
5427 // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
5428 } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
5429 let rhs_ty = self.parse_ty()?;
5430 where_clause.predicates.push(ast::WherePredicate::EqPredicate(
5431 ast::WhereEqPredicate {
5432 span: lo.to(self.prev_span),
5435 id: ast::DUMMY_NODE_ID,
5439 return self.unexpected();
5445 if !self.eat(&token::Comma) {
5450 where_clause.span = lo.to(self.prev_span);
5454 fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
5455 -> PResult<'a, (Vec<Arg> , bool)> {
5456 self.expect(&token::OpenDelim(token::Paren))?;
5459 let mut variadic = false;
5460 let args: Vec<Option<Arg>> =
5461 self.parse_seq_to_before_end(
5462 &token::CloseDelim(token::Paren),
5463 SeqSep::trailing_allowed(token::Comma),
5465 if p.token == token::DotDotDot {
5469 if p.token != token::CloseDelim(token::Paren) {
5472 "`...` must be last in argument list for variadic function");
5476 let span = p.prev_span;
5477 if p.token == token::CloseDelim(token::Paren) {
5478 // continue parsing to present any further errors
5481 "only foreign functions are allowed to be variadic"
5483 Ok(Some(dummy_arg(span)))
5485 // this function definition looks beyond recovery, stop parsing
5487 "only foreign functions are allowed to be variadic");
5492 match p.parse_arg_general(named_args, false) {
5493 Ok(arg) => Ok(Some(arg)),
5496 let lo = p.prev_span;
5497 // Skip every token until next possible arg or end.
5498 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
5499 // Create a placeholder argument for proper arg count (#34264).
5500 let span = lo.to(p.prev_span);
5501 Ok(Some(dummy_arg(span)))
5508 self.eat(&token::CloseDelim(token::Paren));
5510 let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
5512 if variadic && args.is_empty() {
5514 "variadic function must be declared with at least one named argument");
5517 Ok((args, variadic))
5520 /// Parse the argument list and result type of a function declaration
5521 fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
5523 let (args, variadic) = self.parse_fn_args(true, allow_variadic)?;
5524 let ret_ty = self.parse_ret_ty(true)?;
5533 /// Returns the parsed optional self argument and whether a self shortcut was used.
5534 fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
5535 let expect_ident = |this: &mut Self| match this.token {
5536 // Preserve hygienic context.
5537 token::Ident(ident, _) =>
5538 { let span = this.span; this.bump(); Ident::new(ident.name, span) }
5541 let isolated_self = |this: &mut Self, n| {
5542 this.look_ahead(n, |t| t.is_keyword(keywords::SelfLower)) &&
5543 this.look_ahead(n + 1, |t| t != &token::ModSep)
5546 // Parse optional self parameter of a method.
5547 // Only a limited set of initial token sequences is considered self parameters, anything
5548 // else is parsed as a normal function parameter list, so some lookahead is required.
5549 let eself_lo = self.span;
5550 let (eself, eself_ident, eself_hi) = match self.token {
5551 token::BinOp(token::And) => {
5557 (if isolated_self(self, 1) {
5559 SelfKind::Region(None, Mutability::Immutable)
5560 } else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
5561 isolated_self(self, 2) {
5564 SelfKind::Region(None, Mutability::Mutable)
5565 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5566 isolated_self(self, 2) {
5568 let lt = self.expect_lifetime();
5569 SelfKind::Region(Some(lt), Mutability::Immutable)
5570 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5571 self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
5572 isolated_self(self, 3) {
5574 let lt = self.expect_lifetime();
5576 SelfKind::Region(Some(lt), Mutability::Mutable)
5579 }, expect_ident(self), self.prev_span)
5581 token::BinOp(token::Star) => {
5586 // Emit special error for `self` cases.
5587 (if isolated_self(self, 1) {
5589 self.span_err(self.span, "cannot pass `self` by raw pointer");
5590 SelfKind::Value(Mutability::Immutable)
5591 } else if self.look_ahead(1, |t| t.is_mutability()) &&
5592 isolated_self(self, 2) {
5595 self.span_err(self.span, "cannot pass `self` by raw pointer");
5596 SelfKind::Value(Mutability::Immutable)
5599 }, expect_ident(self), self.prev_span)
5601 token::Ident(..) => {
5602 if isolated_self(self, 0) {
5605 let eself_ident = expect_ident(self);
5606 let eself_hi = self.prev_span;
5607 (if self.eat(&token::Colon) {
5608 let ty = self.parse_ty()?;
5609 SelfKind::Explicit(ty, Mutability::Immutable)
5611 SelfKind::Value(Mutability::Immutable)
5612 }, eself_ident, eself_hi)
5613 } else if self.token.is_keyword(keywords::Mut) &&
5614 isolated_self(self, 1) {
5618 let eself_ident = expect_ident(self);
5619 let eself_hi = self.prev_span;
5620 (if self.eat(&token::Colon) {
5621 let ty = self.parse_ty()?;
5622 SelfKind::Explicit(ty, Mutability::Mutable)
5624 SelfKind::Value(Mutability::Mutable)
5625 }, eself_ident, eself_hi)
5630 _ => return Ok(None),
5633 let eself = source_map::respan(eself_lo.to(eself_hi), eself);
5634 Ok(Some(Arg::from_self(eself, eself_ident)))
5637 /// Parse the parameter list and result type of a function that may have a `self` parameter.
5638 fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>>
5639 where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
5641 self.expect(&token::OpenDelim(token::Paren))?;
5643 // Parse optional self argument
5644 let self_arg = self.parse_self_arg()?;
5646 // Parse the rest of the function parameter list.
5647 let sep = SeqSep::trailing_allowed(token::Comma);
5648 let fn_inputs = if let Some(self_arg) = self_arg {
5649 if self.check(&token::CloseDelim(token::Paren)) {
5651 } else if self.eat(&token::Comma) {
5652 let mut fn_inputs = vec![self_arg];
5653 fn_inputs.append(&mut self.parse_seq_to_before_end(
5654 &token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5658 return self.unexpected();
5661 self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5664 // Parse closing paren and return type.
5665 self.expect(&token::CloseDelim(token::Paren))?;
5668 output: self.parse_ret_ty(true)?,
5673 // parse the |arg, arg| header on a lambda
5674 fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
5675 let inputs_captures = {
5676 if self.eat(&token::OrOr) {
5679 self.expect(&token::BinOp(token::Or))?;
5680 let args = self.parse_seq_to_before_tokens(
5681 &[&token::BinOp(token::Or), &token::OrOr],
5682 SeqSep::trailing_allowed(token::Comma),
5683 TokenExpectType::NoExpect,
5684 |p| p.parse_fn_block_arg()
5690 let output = self.parse_ret_ty(true)?;
5693 inputs: inputs_captures,
5699 /// Parse the name and optional generic types of a function header.
5700 fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
5701 let id = self.parse_ident()?;
5702 let generics = self.parse_generics()?;
5706 fn mk_item(&mut self, span: Span, ident: Ident, node: ItemKind, vis: Visibility,
5707 attrs: Vec<Attribute>) -> P<Item> {
5711 id: ast::DUMMY_NODE_ID,
5719 /// Parse an item-position function declaration.
5720 fn parse_item_fn(&mut self,
5723 constness: Spanned<Constness>,
5725 -> PResult<'a, ItemInfo> {
5726 let (ident, mut generics) = self.parse_fn_header()?;
5727 let decl = self.parse_fn_decl(false)?;
5728 generics.where_clause = self.parse_where_clause()?;
5729 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5730 let header = FnHeader { unsafety, asyncness, constness, abi };
5731 Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
5734 /// true if we are looking at `const ID`, false for things like `const fn` etc
5735 fn is_const_item(&mut self) -> bool {
5736 self.token.is_keyword(keywords::Const) &&
5737 !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
5738 !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
5741 /// parses all the "front matter" for a `fn` declaration, up to
5742 /// and including the `fn` keyword:
5746 /// - `const unsafe fn`
5749 fn parse_fn_front_matter(&mut self)
5757 let is_const_fn = self.eat_keyword(keywords::Const);
5758 let const_span = self.prev_span;
5759 let unsafety = self.parse_unsafety();
5760 let asyncness = self.parse_asyncness();
5761 let (constness, unsafety, abi) = if is_const_fn {
5762 (respan(const_span, Constness::Const), unsafety, Abi::Rust)
5764 let abi = if self.eat_keyword(keywords::Extern) {
5765 self.parse_opt_abi()?.unwrap_or(Abi::C)
5769 (respan(self.prev_span, Constness::NotConst), unsafety, abi)
5771 self.expect_keyword(keywords::Fn)?;
5772 Ok((constness, unsafety, asyncness, abi))
5775 /// Parse an impl item.
5776 pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
5777 maybe_whole!(self, NtImplItem, |x| x);
5778 let attrs = self.parse_outer_attributes()?;
5779 let (mut item, tokens) = self.collect_tokens(|this| {
5780 this.parse_impl_item_(at_end, attrs)
5783 // See `parse_item` for why this clause is here.
5784 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
5785 item.tokens = Some(tokens);
5790 fn parse_impl_item_(&mut self,
5792 mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> {
5794 let vis = self.parse_visibility(false)?;
5795 let defaultness = self.parse_defaultness();
5796 let (name, node, generics) = if let Some(type_) = self.eat_type() {
5797 let (name, alias, generics) = type_?;
5798 let kind = match alias {
5799 AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ),
5800 AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds),
5802 (name, kind, generics)
5803 } else if self.is_const_item() {
5804 // This parses the grammar:
5805 // ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
5806 self.expect_keyword(keywords::Const)?;
5807 let name = self.parse_ident()?;
5808 self.expect(&token::Colon)?;
5809 let typ = self.parse_ty()?;
5810 self.expect(&token::Eq)?;
5811 let expr = self.parse_expr()?;
5812 self.expect(&token::Semi)?;
5813 (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default())
5815 let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?;
5816 attrs.extend(inner_attrs);
5817 (name, node, generics)
5821 id: ast::DUMMY_NODE_ID,
5822 span: lo.to(self.prev_span),
5833 fn complain_if_pub_macro(&mut self, vis: &VisibilityKind, sp: Span) {
5835 VisibilityKind::Inherited => {}
5837 let is_macro_rules: bool = match self.token {
5838 token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"),
5841 let mut err = if is_macro_rules {
5842 let mut err = self.diagnostic()
5843 .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
5844 err.span_suggestion_with_applicability(
5846 "try exporting the macro",
5847 "#[macro_export]".to_owned(),
5848 Applicability::MaybeIncorrect // speculative
5852 let mut err = self.diagnostic()
5853 .struct_span_err(sp, "can't qualify macro invocation with `pub`");
5854 err.help("try adjusting the macro to put `pub` inside the invocation");
5862 fn missing_assoc_item_kind_err(&mut self, item_type: &str, prev_span: Span)
5863 -> DiagnosticBuilder<'a>
5865 let expected_kinds = if item_type == "extern" {
5866 "missing `fn`, `type`, or `static`"
5868 "missing `fn`, `type`, or `const`"
5871 // Given this code `path(`, it seems like this is not
5872 // setting the visibility of a macro invocation, but rather
5873 // a mistyped method declaration.
5874 // Create a diagnostic pointing out that `fn` is missing.
5876 // x | pub path(&self) {
5877 // | ^ missing `fn`, `type`, or `const`
5879 // ^^ `sp` below will point to this
5880 let sp = prev_span.between(self.prev_span);
5881 let mut err = self.diagnostic().struct_span_err(
5883 &format!("{} for {}-item declaration",
5884 expected_kinds, item_type));
5885 err.span_label(sp, expected_kinds);
5889 /// Parse a method or a macro invocation in a trait impl.
5890 fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
5891 -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics,
5892 ast::ImplItemKind)> {
5893 // code copied from parse_macro_use_or_failure... abstraction!
5894 if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
5896 Ok((keywords::Invalid.ident(), vec![], ast::Generics::default(),
5897 ast::ImplItemKind::Macro(mac)))
5899 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
5900 let ident = self.parse_ident()?;
5901 let mut generics = self.parse_generics()?;
5902 let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
5903 generics.where_clause = self.parse_where_clause()?;
5905 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5906 let header = ast::FnHeader { abi, unsafety, constness, asyncness };
5907 Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
5908 ast::MethodSig { header, decl },
5914 /// Parse `trait Foo { ... }` or `trait Foo = Bar;`
5915 fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5916 let ident = self.parse_ident()?;
5917 let mut tps = self.parse_generics()?;
5919 // Parse optional colon and supertrait bounds.
5920 let bounds = if self.eat(&token::Colon) {
5921 self.parse_generic_bounds()?
5926 if self.eat(&token::Eq) {
5927 // it's a trait alias
5928 let bounds = self.parse_generic_bounds()?;
5929 tps.where_clause = self.parse_where_clause()?;
5930 self.expect(&token::Semi)?;
5931 if unsafety != Unsafety::Normal {
5932 self.span_err(self.prev_span, "trait aliases cannot be unsafe");
5934 Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
5936 // it's a normal trait
5937 tps.where_clause = self.parse_where_clause()?;
5938 self.expect(&token::OpenDelim(token::Brace))?;
5939 let mut trait_items = vec![];
5940 while !self.eat(&token::CloseDelim(token::Brace)) {
5941 let mut at_end = false;
5942 match self.parse_trait_item(&mut at_end) {
5943 Ok(item) => trait_items.push(item),
5947 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5952 Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
5956 fn choose_generics_over_qpath(&self) -> bool {
5957 // There's an ambiguity between generic parameters and qualified paths in impls.
5958 // If we see `<` it may start both, so we have to inspect some following tokens.
5959 // The following combinations can only start generics,
5960 // but not qualified paths (with one exception):
5961 // `<` `>` - empty generic parameters
5962 // `<` `#` - generic parameters with attributes
5963 // `<` (LIFETIME|IDENT) `>` - single generic parameter
5964 // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
5965 // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
5966 // `<` (LIFETIME|IDENT) `=` - generic parameter with a default
5967 // The only truly ambiguous case is
5968 // `<` IDENT `>` `::` IDENT ...
5969 // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
5970 // because this is what almost always expected in practice, qualified paths in impls
5971 // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
5972 self.token == token::Lt &&
5973 (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
5974 self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
5975 self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
5976 t == &token::Colon || t == &token::Eq))
5979 fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
5980 self.expect(&token::OpenDelim(token::Brace))?;
5981 let attrs = self.parse_inner_attributes()?;
5983 let mut impl_items = Vec::new();
5984 while !self.eat(&token::CloseDelim(token::Brace)) {
5985 let mut at_end = false;
5986 match self.parse_impl_item(&mut at_end) {
5987 Ok(impl_item) => impl_items.push(impl_item),
5991 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5996 Ok((impl_items, attrs))
5999 /// Parses an implementation item, `impl` keyword is already parsed.
6000 /// impl<'a, T> TYPE { /* impl items */ }
6001 /// impl<'a, T> TRAIT for TYPE { /* impl items */ }
6002 /// impl<'a, T> !TRAIT for TYPE { /* impl items */ }
6003 /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
6004 /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
6005 /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
6006 fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
6007 -> PResult<'a, ItemInfo> {
6008 // First, parse generic parameters if necessary.
6009 let mut generics = if self.choose_generics_over_qpath() {
6010 self.parse_generics()?
6012 ast::Generics::default()
6015 // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
6016 let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
6018 ast::ImplPolarity::Negative
6020 ast::ImplPolarity::Positive
6023 // Parse both types and traits as a type, then reinterpret if necessary.
6024 let ty_first = self.parse_ty()?;
6026 // If `for` is missing we try to recover.
6027 let has_for = self.eat_keyword(keywords::For);
6028 let missing_for_span = self.prev_span.between(self.span);
6030 let ty_second = if self.token == token::DotDot {
6031 // We need to report this error after `cfg` expansion for compatibility reasons
6032 self.bump(); // `..`, do not add it to expected tokens
6033 Some(P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID }))
6034 } else if has_for || self.token.can_begin_type() {
6035 Some(self.parse_ty()?)
6040 generics.where_clause = self.parse_where_clause()?;
6042 let (impl_items, attrs) = self.parse_impl_body()?;
6044 let item_kind = match ty_second {
6045 Some(ty_second) => {
6046 // impl Trait for Type
6048 self.span_err(missing_for_span, "missing `for` in a trait impl");
6051 let ty_first = ty_first.into_inner();
6052 let path = match ty_first.node {
6053 // This notably includes paths passed through `ty` macro fragments (#46438).
6054 TyKind::Path(None, path) => path,
6056 self.span_err(ty_first.span, "expected a trait, found type");
6057 ast::Path::from_ident(Ident::new(keywords::Invalid.name(), ty_first.span))
6060 let trait_ref = TraitRef { path, ref_id: ty_first.id };
6062 ItemKind::Impl(unsafety, polarity, defaultness,
6063 generics, Some(trait_ref), ty_second, impl_items)
6067 ItemKind::Impl(unsafety, polarity, defaultness,
6068 generics, None, ty_first, impl_items)
6072 Ok((keywords::Invalid.ident(), item_kind, Some(attrs)))
6075 fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
6076 if self.eat_keyword(keywords::For) {
6078 let params = self.parse_generic_params()?;
6080 // We rely on AST validation to rule out invalid cases: There must not be type
6081 // parameters, and the lifetime parameters must not have bounds.
6088 /// Parse struct Foo { ... }
6089 fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
6090 let class_name = self.parse_ident()?;
6092 let mut generics = self.parse_generics()?;
6094 // There is a special case worth noting here, as reported in issue #17904.
6095 // If we are parsing a tuple struct it is the case that the where clause
6096 // should follow the field list. Like so:
6098 // struct Foo<T>(T) where T: Copy;
6100 // If we are parsing a normal record-style struct it is the case
6101 // that the where clause comes before the body, and after the generics.
6102 // So if we look ahead and see a brace or a where-clause we begin
6103 // parsing a record style struct.
6105 // Otherwise if we look ahead and see a paren we parse a tuple-style
6108 let vdata = if self.token.is_keyword(keywords::Where) {
6109 generics.where_clause = self.parse_where_clause()?;
6110 if self.eat(&token::Semi) {
6111 // If we see a: `struct Foo<T> where T: Copy;` style decl.
6112 VariantData::Unit(ast::DUMMY_NODE_ID)
6114 // If we see: `struct Foo<T> where T: Copy { ... }`
6115 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6117 // No `where` so: `struct Foo<T>;`
6118 } else if self.eat(&token::Semi) {
6119 VariantData::Unit(ast::DUMMY_NODE_ID)
6120 // Record-style struct definition
6121 } else if self.token == token::OpenDelim(token::Brace) {
6122 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6123 // Tuple-style struct definition with optional where-clause.
6124 } else if self.token == token::OpenDelim(token::Paren) {
6125 let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID);
6126 generics.where_clause = self.parse_where_clause()?;
6127 self.expect(&token::Semi)?;
6130 let token_str = self.this_token_descr();
6131 let mut err = self.fatal(&format!(
6132 "expected `where`, `{{`, `(`, or `;` after struct name, found {}",
6135 err.span_label(self.span, "expected `where`, `{`, `(`, or `;` after struct name");
6139 Ok((class_name, ItemKind::Struct(vdata, generics), None))
6142 /// Parse union Foo { ... }
6143 fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
6144 let class_name = self.parse_ident()?;
6146 let mut generics = self.parse_generics()?;
6148 let vdata = if self.token.is_keyword(keywords::Where) {
6149 generics.where_clause = self.parse_where_clause()?;
6150 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6151 } else if self.token == token::OpenDelim(token::Brace) {
6152 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6154 let token_str = self.this_token_descr();
6155 let mut err = self.fatal(&format!(
6156 "expected `where` or `{{` after union name, found {}", token_str));
6157 err.span_label(self.span, "expected `where` or `{` after union name");
6161 Ok((class_name, ItemKind::Union(vdata, generics), None))
6164 fn consume_block(&mut self, delim: token::DelimToken) {
6165 let mut brace_depth = 0;
6167 if self.eat(&token::OpenDelim(delim)) {
6169 } else if self.eat(&token::CloseDelim(delim)) {
6170 if brace_depth == 0 {
6176 } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
6184 fn parse_record_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6185 let mut fields = Vec::new();
6186 if self.eat(&token::OpenDelim(token::Brace)) {
6187 while self.token != token::CloseDelim(token::Brace) {
6188 let field = self.parse_struct_decl_field().map_err(|e| {
6189 self.recover_stmt();
6193 Ok(field) => fields.push(field),
6199 self.eat(&token::CloseDelim(token::Brace));
6201 let token_str = self.this_token_descr();
6202 let mut err = self.fatal(&format!(
6203 "expected `where`, or `{{` after struct name, found {}", token_str));
6204 err.span_label(self.span, "expected `where`, or `{` after struct name");
6211 fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6212 // This is the case where we find `struct Foo<T>(T) where T: Copy;`
6213 // Unit like structs are handled in parse_item_struct function
6214 let fields = self.parse_unspanned_seq(
6215 &token::OpenDelim(token::Paren),
6216 &token::CloseDelim(token::Paren),
6217 SeqSep::trailing_allowed(token::Comma),
6219 let attrs = p.parse_outer_attributes()?;
6221 let vis = p.parse_visibility(true)?;
6222 let ty = p.parse_ty()?;
6224 span: lo.to(ty.span),
6227 id: ast::DUMMY_NODE_ID,
6236 /// Parse a structure field declaration
6237 fn parse_single_struct_field(&mut self,
6240 attrs: Vec<Attribute> )
6241 -> PResult<'a, StructField> {
6242 let mut seen_comma: bool = false;
6243 let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
6244 if self.token == token::Comma {
6251 token::CloseDelim(token::Brace) => {}
6252 token::DocComment(_) => {
6253 let previous_span = self.prev_span;
6254 let mut err = self.span_fatal_err(self.span, Error::UselessDocComment);
6255 self.bump(); // consume the doc comment
6256 let comma_after_doc_seen = self.eat(&token::Comma);
6257 // `seen_comma` is always false, because we are inside doc block
6258 // condition is here to make code more readable
6259 if seen_comma == false && comma_after_doc_seen == true {
6262 if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
6265 if seen_comma == false {
6266 let sp = self.sess.source_map().next_point(previous_span);
6267 err.span_suggestion_with_applicability(
6269 "missing comma here",
6271 Applicability::MachineApplicable
6278 let sp = self.sess.source_map().next_point(self.prev_span);
6279 let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}",
6280 self.this_token_descr()));
6281 if self.token.is_ident() {
6282 // This is likely another field; emit the diagnostic and keep going
6283 err.span_suggestion_with_applicability(
6285 "try adding a comma",
6287 Applicability::MachineApplicable,
6298 /// Parse an element of a struct definition
6299 fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
6300 let attrs = self.parse_outer_attributes()?;
6302 let vis = self.parse_visibility(false)?;
6303 self.parse_single_struct_field(lo, vis, attrs)
6306 /// Parse `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
6307 /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
6308 /// If the following element can't be a tuple (i.e., it's a function definition,
6309 /// it's not a tuple struct field) and the contents within the parens
6310 /// isn't valid, emit a proper diagnostic.
6311 pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
6312 maybe_whole!(self, NtVis, |x| x);
6314 self.expected_tokens.push(TokenType::Keyword(keywords::Crate));
6315 if self.is_crate_vis() {
6316 self.bump(); // `crate`
6317 return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
6320 if !self.eat_keyword(keywords::Pub) {
6321 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
6322 // keyword to grab a span from for inherited visibility; an empty span at the
6323 // beginning of the current token would seem to be the "Schelling span".
6324 return Ok(respan(self.span.shrink_to_lo(), VisibilityKind::Inherited))
6326 let lo = self.prev_span;
6328 if self.check(&token::OpenDelim(token::Paren)) {
6329 // We don't `self.bump()` the `(` yet because this might be a struct definition where
6330 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
6331 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
6332 // by the following tokens.
6333 if self.look_ahead(1, |t| t.is_keyword(keywords::Crate)) {
6336 self.bump(); // `crate`
6337 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6339 lo.to(self.prev_span),
6340 VisibilityKind::Crate(CrateSugar::PubCrate),
6343 } else if self.look_ahead(1, |t| t.is_keyword(keywords::In)) {
6346 self.bump(); // `in`
6347 let path = self.parse_path(PathStyle::Mod)?; // `path`
6348 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6349 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6351 id: ast::DUMMY_NODE_ID,
6354 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
6355 self.look_ahead(1, |t| t.is_keyword(keywords::Super) ||
6356 t.is_keyword(keywords::SelfLower))
6358 // `pub(self)` or `pub(super)`
6360 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
6361 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6362 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6364 id: ast::DUMMY_NODE_ID,
6367 } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct
6368 // `pub(something) fn ...` or `struct X { pub(something) y: Z }`
6370 let msg = "incorrect visibility restriction";
6371 let suggestion = r##"some possible visibility restrictions are:
6372 `pub(crate)`: visible only on the current crate
6373 `pub(super)`: visible only in the current module's parent
6374 `pub(in path::to::module)`: visible only on the specified path"##;
6375 let path = self.parse_path(PathStyle::Mod)?;
6376 let sp = self.prev_span;
6377 let help_msg = format!("make this visible only to module `{}` with `in`", path);
6378 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6379 let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg);
6380 err.help(suggestion);
6381 err.span_suggestion_with_applicability(
6382 sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable
6384 err.emit(); // emit diagnostic, but continue with public visibility
6388 Ok(respan(lo, VisibilityKind::Public))
6391 /// Parse defaultness: `default` or nothing.
6392 fn parse_defaultness(&mut self) -> Defaultness {
6393 // `pub` is included for better error messages
6394 if self.check_keyword(keywords::Default) &&
6395 self.look_ahead(1, |t| t.is_keyword(keywords::Impl) ||
6396 t.is_keyword(keywords::Const) ||
6397 t.is_keyword(keywords::Fn) ||
6398 t.is_keyword(keywords::Unsafe) ||
6399 t.is_keyword(keywords::Extern) ||
6400 t.is_keyword(keywords::Type) ||
6401 t.is_keyword(keywords::Pub)) {
6402 self.bump(); // `default`
6403 Defaultness::Default
6409 /// Given a termination token, parse all of the items in a module
6410 fn parse_mod_items(&mut self, term: &token::Token, inner_lo: Span) -> PResult<'a, Mod> {
6411 let mut items = vec![];
6412 while let Some(item) = self.parse_item()? {
6416 if !self.eat(term) {
6417 let token_str = self.this_token_descr();
6418 let mut err = self.fatal(&format!("expected item, found {}", token_str));
6419 if self.token == token::Semi {
6420 let msg = "consider removing this semicolon";
6421 err.span_suggestion_short_with_applicability(
6422 self.span, msg, String::new(), Applicability::MachineApplicable
6424 if !items.is_empty() { // Issue #51603
6425 let previous_item = &items[items.len()-1];
6426 let previous_item_kind_name = match previous_item.node {
6427 // say "braced struct" because tuple-structs and
6428 // braceless-empty-struct declarations do take a semicolon
6429 ItemKind::Struct(..) => Some("braced struct"),
6430 ItemKind::Enum(..) => Some("enum"),
6431 ItemKind::Trait(..) => Some("trait"),
6432 ItemKind::Union(..) => Some("union"),
6435 if let Some(name) = previous_item_kind_name {
6436 err.help(&format!("{} declarations are not followed by a semicolon",
6441 err.span_label(self.span, "expected item");
6446 let hi = if self.span.is_dummy() {
6453 inner: inner_lo.to(hi),
6459 fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
6460 let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?;
6461 self.expect(&token::Colon)?;
6462 let ty = self.parse_ty()?;
6463 self.expect(&token::Eq)?;
6464 let e = self.parse_expr()?;
6465 self.expect(&token::Semi)?;
6466 let item = match m {
6467 Some(m) => ItemKind::Static(ty, m, e),
6468 None => ItemKind::Const(ty, e),
6470 Ok((id, item, None))
6473 /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
6474 fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
6475 let (in_cfg, outer_attrs) = {
6476 let mut strip_unconfigured = ::config::StripUnconfigured {
6478 features: None, // don't perform gated feature checking
6480 let outer_attrs = strip_unconfigured.process_cfg_attrs(outer_attrs.to_owned());
6481 (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), outer_attrs)
6484 let id_span = self.span;
6485 let id = self.parse_ident()?;
6486 if self.eat(&token::Semi) {
6487 if in_cfg && self.recurse_into_file_modules {
6488 // This mod is in an external file. Let's go get it!
6489 let ModulePathSuccess { path, directory_ownership, warn } =
6490 self.submod_path(id, &outer_attrs, id_span)?;
6491 let (module, mut attrs) =
6492 self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
6493 // Record that we fetched the mod from an external file
6495 let attr = Attribute {
6496 id: attr::mk_attr_id(),
6497 style: ast::AttrStyle::Outer,
6498 path: ast::Path::from_ident(Ident::from_str("warn_directory_ownership")),
6499 tokens: TokenStream::empty(),
6500 is_sugared_doc: false,
6501 span: syntax_pos::DUMMY_SP,
6503 attr::mark_known(&attr);
6506 Ok((id, ItemKind::Mod(module), Some(attrs)))
6508 let placeholder = ast::Mod {
6509 inner: syntax_pos::DUMMY_SP,
6513 Ok((id, ItemKind::Mod(placeholder), None))
6516 let old_directory = self.directory.clone();
6517 self.push_directory(id, &outer_attrs);
6519 self.expect(&token::OpenDelim(token::Brace))?;
6520 let mod_inner_lo = self.span;
6521 let attrs = self.parse_inner_attributes()?;
6522 let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
6524 self.directory = old_directory;
6525 Ok((id, ItemKind::Mod(module), Some(attrs)))
6529 fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
6530 if let Some(path) = attr::first_attr_value_str_by_name(attrs, "path") {
6531 self.directory.path.to_mut().push(&path.as_str());
6532 self.directory.ownership = DirectoryOwnership::Owned { relative: None };
6534 // We have to push on the current module name in the case of relative
6535 // paths in order to ensure that any additional module paths from inline
6536 // `mod x { ... }` come after the relative extension.
6538 // For example, a `mod z { ... }` inside `x/y.rs` should set the current
6539 // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
6540 if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
6541 if let Some(ident) = relative.take() { // remove the relative offset
6542 self.directory.path.to_mut().push(ident.as_str());
6545 self.directory.path.to_mut().push(&id.as_str());
6549 pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
6550 if let Some(s) = attr::first_attr_value_str_by_name(attrs, "path") {
6553 // On windows, the base path might have the form
6554 // `\\?\foo\bar` in which case it does not tolerate
6555 // mixed `/` and `\` separators, so canonicalize
6558 let s = s.replace("/", "\\");
6559 Some(dir_path.join(s))
6565 /// Returns either a path to a module, or .
6566 pub fn default_submod_path(
6568 relative: Option<ast::Ident>,
6570 source_map: &SourceMap) -> ModulePath
6572 // If we're in a foo.rs file instead of a mod.rs file,
6573 // we need to look for submodules in
6574 // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
6575 // `./<id>.rs` and `./<id>/mod.rs`.
6576 let relative_prefix_string;
6577 let relative_prefix = if let Some(ident) = relative {
6578 relative_prefix_string = format!("{}{}", ident.as_str(), path::MAIN_SEPARATOR);
6579 &relative_prefix_string
6584 let mod_name = id.to_string();
6585 let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
6586 let secondary_path_str = format!("{}{}{}mod.rs",
6587 relative_prefix, mod_name, path::MAIN_SEPARATOR);
6588 let default_path = dir_path.join(&default_path_str);
6589 let secondary_path = dir_path.join(&secondary_path_str);
6590 let default_exists = source_map.file_exists(&default_path);
6591 let secondary_exists = source_map.file_exists(&secondary_path);
6593 let result = match (default_exists, secondary_exists) {
6594 (true, false) => Ok(ModulePathSuccess {
6596 directory_ownership: DirectoryOwnership::Owned {
6601 (false, true) => Ok(ModulePathSuccess {
6602 path: secondary_path,
6603 directory_ownership: DirectoryOwnership::Owned {
6608 (false, false) => Err(Error::FileNotFoundForModule {
6609 mod_name: mod_name.clone(),
6610 default_path: default_path_str,
6611 secondary_path: secondary_path_str,
6612 dir_path: dir_path.display().to_string(),
6614 (true, true) => Err(Error::DuplicatePaths {
6615 mod_name: mod_name.clone(),
6616 default_path: default_path_str,
6617 secondary_path: secondary_path_str,
6623 path_exists: default_exists || secondary_exists,
6628 fn submod_path(&mut self,
6630 outer_attrs: &[Attribute],
6632 -> PResult<'a, ModulePathSuccess> {
6633 if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
6634 return Ok(ModulePathSuccess {
6635 directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
6636 // All `#[path]` files are treated as though they are a `mod.rs` file.
6637 // This means that `mod foo;` declarations inside `#[path]`-included
6638 // files are siblings,
6640 // Note that this will produce weirdness when a file named `foo.rs` is
6641 // `#[path]` included and contains a `mod foo;` declaration.
6642 // If you encounter this, it's your own darn fault :P
6643 Some(_) => DirectoryOwnership::Owned { relative: None },
6644 _ => DirectoryOwnership::UnownedViaMod(true),
6651 let relative = match self.directory.ownership {
6652 DirectoryOwnership::Owned { relative } => relative,
6653 DirectoryOwnership::UnownedViaBlock |
6654 DirectoryOwnership::UnownedViaMod(_) => None,
6656 let paths = Parser::default_submod_path(
6657 id, relative, &self.directory.path, self.sess.source_map());
6659 match self.directory.ownership {
6660 DirectoryOwnership::Owned { .. } => {
6661 paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
6663 DirectoryOwnership::UnownedViaBlock => {
6665 "Cannot declare a non-inline module inside a block \
6666 unless it has a path attribute";
6667 let mut err = self.diagnostic().struct_span_err(id_sp, msg);
6668 if paths.path_exists {
6669 let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
6671 err.span_note(id_sp, &msg);
6675 DirectoryOwnership::UnownedViaMod(warn) => {
6677 if let Ok(result) = paths.result {
6678 return Ok(ModulePathSuccess { warn: true, ..result });
6681 let mut err = self.diagnostic().struct_span_err(id_sp,
6682 "cannot declare a new module at this location");
6683 if !id_sp.is_dummy() {
6684 let src_path = self.sess.source_map().span_to_filename(id_sp);
6685 if let FileName::Real(src_path) = src_path {
6686 if let Some(stem) = src_path.file_stem() {
6687 let mut dest_path = src_path.clone();
6688 dest_path.set_file_name(stem);
6689 dest_path.push("mod.rs");
6690 err.span_note(id_sp,
6691 &format!("maybe move this module `{}` to its own \
6692 directory via `{}`", src_path.display(),
6693 dest_path.display()));
6697 if paths.path_exists {
6698 err.span_note(id_sp,
6699 &format!("... or maybe `use` the module `{}` instead \
6700 of possibly redeclaring it",
6708 /// Read a module from a source file.
6709 fn eval_src_mod(&mut self,
6711 directory_ownership: DirectoryOwnership,
6714 -> PResult<'a, (ast::Mod, Vec<Attribute> )> {
6715 let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
6716 if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
6717 let mut err = String::from("circular modules: ");
6718 let len = included_mod_stack.len();
6719 for p in &included_mod_stack[i.. len] {
6720 err.push_str(&p.to_string_lossy());
6721 err.push_str(" -> ");
6723 err.push_str(&path.to_string_lossy());
6724 return Err(self.span_fatal(id_sp, &err[..]));
6726 included_mod_stack.push(path.clone());
6727 drop(included_mod_stack);
6730 new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
6731 p0.cfg_mods = self.cfg_mods;
6732 let mod_inner_lo = p0.span;
6733 let mod_attrs = p0.parse_inner_attributes()?;
6734 let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
6736 self.sess.included_mod_stack.borrow_mut().pop();
6740 /// Parse a function declaration from a foreign module
6741 fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6742 -> PResult<'a, ForeignItem> {
6743 self.expect_keyword(keywords::Fn)?;
6745 let (ident, mut generics) = self.parse_fn_header()?;
6746 let decl = self.parse_fn_decl(true)?;
6747 generics.where_clause = self.parse_where_clause()?;
6749 self.expect(&token::Semi)?;
6750 Ok(ast::ForeignItem {
6753 node: ForeignItemKind::Fn(decl, generics),
6754 id: ast::DUMMY_NODE_ID,
6760 /// Parse a static item from a foreign module.
6761 /// Assumes that the `static` keyword is already parsed.
6762 fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6763 -> PResult<'a, ForeignItem> {
6764 let mutbl = self.eat_keyword(keywords::Mut);
6765 let ident = self.parse_ident()?;
6766 self.expect(&token::Colon)?;
6767 let ty = self.parse_ty()?;
6769 self.expect(&token::Semi)?;
6773 node: ForeignItemKind::Static(ty, mutbl),
6774 id: ast::DUMMY_NODE_ID,
6780 /// Parse a type from a foreign module
6781 fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6782 -> PResult<'a, ForeignItem> {
6783 self.expect_keyword(keywords::Type)?;
6785 let ident = self.parse_ident()?;
6787 self.expect(&token::Semi)?;
6788 Ok(ast::ForeignItem {
6791 node: ForeignItemKind::Ty,
6792 id: ast::DUMMY_NODE_ID,
6798 fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
6799 let error_msg = "crate name using dashes are not valid in `extern crate` statements";
6800 let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
6802 let mut ident = if self.token.is_keyword(keywords::SelfLower) {
6803 self.parse_path_segment_ident()
6807 let mut idents = vec![];
6808 let mut replacement = vec![];
6809 let mut fixed_crate_name = false;
6810 // Accept `extern crate name-like-this` for better diagnostics
6811 let dash = token::Token::BinOp(token::BinOpToken::Minus);
6812 if self.token == dash { // Do not include `-` as part of the expected tokens list
6813 while self.eat(&dash) {
6814 fixed_crate_name = true;
6815 replacement.push((self.prev_span, "_".to_string()));
6816 idents.push(self.parse_ident()?);
6819 if fixed_crate_name {
6820 let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
6821 let mut fixed_name = format!("{}", ident.name);
6822 for part in idents {
6823 fixed_name.push_str(&format!("_{}", part.name));
6825 ident = Ident::from_str(&fixed_name).with_span_pos(fixed_name_sp);
6827 let mut err = self.struct_span_err(fixed_name_sp, error_msg);
6828 err.span_label(fixed_name_sp, "dash-separated idents are not valid");
6829 err.multipart_suggestion(suggestion_msg, replacement);
6835 /// Parse extern crate links
6839 /// extern crate foo;
6840 /// extern crate bar as foo;
6841 fn parse_item_extern_crate(&mut self,
6843 visibility: Visibility,
6844 attrs: Vec<Attribute>)
6845 -> PResult<'a, P<Item>> {
6846 // Accept `extern crate name-like-this` for better diagnostics
6847 let orig_name = self.parse_crate_name_with_dashes()?;
6848 let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
6849 (rename, Some(orig_name.name))
6853 self.expect(&token::Semi)?;
6855 let span = lo.to(self.prev_span);
6856 Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
6859 /// Parse `extern` for foreign ABIs
6862 /// `extern` is expected to have been
6863 /// consumed before calling this method
6869 fn parse_item_foreign_mod(&mut self,
6871 opt_abi: Option<Abi>,
6872 visibility: Visibility,
6873 mut attrs: Vec<Attribute>)
6874 -> PResult<'a, P<Item>> {
6875 self.expect(&token::OpenDelim(token::Brace))?;
6877 let abi = opt_abi.unwrap_or(Abi::C);
6879 attrs.extend(self.parse_inner_attributes()?);
6881 let mut foreign_items = vec![];
6882 while !self.eat(&token::CloseDelim(token::Brace)) {
6883 foreign_items.push(self.parse_foreign_item()?);
6886 let prev_span = self.prev_span;
6887 let m = ast::ForeignMod {
6889 items: foreign_items
6891 let invalid = keywords::Invalid.ident();
6892 Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
6895 /// Parse `type Foo = Bar;`
6897 /// `existential type Foo: Bar;`
6899 /// `return None` without modifying the parser state
6900 fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
6901 // This parses the grammar:
6902 // Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
6903 if self.check_keyword(keywords::Type) ||
6904 self.check_keyword(keywords::Existential) &&
6905 self.look_ahead(1, |t| t.is_keyword(keywords::Type)) {
6906 let existential = self.eat_keyword(keywords::Existential);
6907 assert!(self.eat_keyword(keywords::Type));
6908 Some(self.parse_existential_or_alias(existential))
6914 /// Parse type alias or existential type
6915 fn parse_existential_or_alias(
6918 ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
6919 let ident = self.parse_ident()?;
6920 let mut tps = self.parse_generics()?;
6921 tps.where_clause = self.parse_where_clause()?;
6922 let alias = if existential {
6923 self.expect(&token::Colon)?;
6924 let bounds = self.parse_generic_bounds()?;
6925 AliasKind::Existential(bounds)
6927 self.expect(&token::Eq)?;
6928 let ty = self.parse_ty()?;
6931 self.expect(&token::Semi)?;
6932 Ok((ident, alias, tps))
6935 /// Parse the part of an "enum" decl following the '{'
6936 fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
6937 let mut variants = Vec::new();
6938 let mut all_nullary = true;
6939 let mut any_disr = None;
6940 while self.token != token::CloseDelim(token::Brace) {
6941 let variant_attrs = self.parse_outer_attributes()?;
6942 let vlo = self.span;
6945 let mut disr_expr = None;
6946 let ident = self.parse_ident()?;
6947 if self.check(&token::OpenDelim(token::Brace)) {
6948 // Parse a struct variant.
6949 all_nullary = false;
6950 struct_def = VariantData::Struct(self.parse_record_struct_body()?,
6951 ast::DUMMY_NODE_ID);
6952 } else if self.check(&token::OpenDelim(token::Paren)) {
6953 all_nullary = false;
6954 struct_def = VariantData::Tuple(self.parse_tuple_struct_body()?,
6955 ast::DUMMY_NODE_ID);
6956 } else if self.eat(&token::Eq) {
6957 disr_expr = Some(AnonConst {
6958 id: ast::DUMMY_NODE_ID,
6959 value: self.parse_expr()?,
6961 any_disr = disr_expr.as_ref().map(|c| c.value.span);
6962 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6964 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6967 let vr = ast::Variant_ {
6969 attrs: variant_attrs,
6973 variants.push(respan(vlo.to(self.prev_span), vr));
6975 if !self.eat(&token::Comma) { break; }
6977 self.expect(&token::CloseDelim(token::Brace))?;
6979 Some(disr_span) if !all_nullary =>
6980 self.span_err(disr_span,
6981 "discriminator values can only be used with a field-less enum"),
6985 Ok(ast::EnumDef { variants })
6988 /// Parse an "enum" declaration
6989 fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
6990 let id = self.parse_ident()?;
6991 let mut generics = self.parse_generics()?;
6992 generics.where_clause = self.parse_where_clause()?;
6993 self.expect(&token::OpenDelim(token::Brace))?;
6995 let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
6996 self.recover_stmt();
6997 self.eat(&token::CloseDelim(token::Brace));
7000 Ok((id, ItemKind::Enum(enum_definition, generics), None))
7003 /// Parses a string as an ABI spec on an extern type or module. Consumes
7004 /// the `extern` keyword, if one is found.
7005 fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
7007 token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
7009 self.expect_no_suffix(sp, "ABI spec", suf);
7011 match abi::lookup(&s.as_str()) {
7012 Some(abi) => Ok(Some(abi)),
7014 let prev_span = self.prev_span;
7015 let mut err = struct_span_err!(
7016 self.sess.span_diagnostic,
7019 "invalid ABI: found `{}`",
7021 err.span_label(prev_span, "invalid ABI");
7022 err.help(&format!("valid ABIs: {}", abi::all_names().join(", ")));
7033 fn is_static_global(&mut self) -> bool {
7034 if self.check_keyword(keywords::Static) {
7035 // Check if this could be a closure
7036 !self.look_ahead(1, |token| {
7037 if token.is_keyword(keywords::Move) {
7041 token::BinOp(token::Or) | token::OrOr => true,
7052 attrs: Vec<Attribute>,
7053 macros_allowed: bool,
7054 attributes_allowed: bool,
7055 ) -> PResult<'a, Option<P<Item>>> {
7056 let (ret, tokens) = self.collect_tokens(|this| {
7057 this.parse_item_implementation(attrs, macros_allowed, attributes_allowed)
7060 // Once we've parsed an item and recorded the tokens we got while
7061 // parsing we may want to store `tokens` into the item we're about to
7062 // return. Note, though, that we specifically didn't capture tokens
7063 // related to outer attributes. The `tokens` field here may later be
7064 // used with procedural macros to convert this item back into a token
7065 // stream, but during expansion we may be removing attributes as we go
7068 // If we've got inner attributes then the `tokens` we've got above holds
7069 // these inner attributes. If an inner attribute is expanded we won't
7070 // actually remove it from the token stream, so we'll just keep yielding
7071 // it (bad!). To work around this case for now we just avoid recording
7072 // `tokens` if we detect any inner attributes. This should help keep
7073 // expansion correct, but we should fix this bug one day!
7076 if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
7077 i.tokens = Some(tokens);
7084 /// Parse one of the items allowed by the flags.
7085 fn parse_item_implementation(
7087 attrs: Vec<Attribute>,
7088 macros_allowed: bool,
7089 attributes_allowed: bool,
7090 ) -> PResult<'a, Option<P<Item>>> {
7091 maybe_whole!(self, NtItem, |item| {
7092 let mut item = item.into_inner();
7093 let mut attrs = attrs;
7094 mem::swap(&mut item.attrs, &mut attrs);
7095 item.attrs.extend(attrs);
7101 let visibility = self.parse_visibility(false)?;
7103 if self.eat_keyword(keywords::Use) {
7105 let item_ = ItemKind::Use(P(self.parse_use_tree()?));
7106 self.expect(&token::Semi)?;
7108 let span = lo.to(self.prev_span);
7109 let item = self.mk_item(span, keywords::Invalid.ident(), item_, visibility, attrs);
7110 return Ok(Some(item));
7113 if self.check_keyword(keywords::Extern) && self.is_extern_non_path() {
7114 self.bump(); // `extern`
7115 if self.eat_keyword(keywords::Crate) {
7116 return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
7119 let opt_abi = self.parse_opt_abi()?;
7121 if self.eat_keyword(keywords::Fn) {
7122 // EXTERN FUNCTION ITEM
7123 let fn_span = self.prev_span;
7124 let abi = opt_abi.unwrap_or(Abi::C);
7125 let (ident, item_, extra_attrs) =
7126 self.parse_item_fn(Unsafety::Normal,
7128 respan(fn_span, Constness::NotConst),
7130 let prev_span = self.prev_span;
7131 let item = self.mk_item(lo.to(prev_span),
7135 maybe_append(attrs, extra_attrs));
7136 return Ok(Some(item));
7137 } else if self.check(&token::OpenDelim(token::Brace)) {
7138 return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
7144 if self.is_static_global() {
7147 let m = if self.eat_keyword(keywords::Mut) {
7150 Mutability::Immutable
7152 let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
7153 let prev_span = self.prev_span;
7154 let item = self.mk_item(lo.to(prev_span),
7158 maybe_append(attrs, extra_attrs));
7159 return Ok(Some(item));
7161 if self.eat_keyword(keywords::Const) {
7162 let const_span = self.prev_span;
7163 if self.check_keyword(keywords::Fn)
7164 || (self.check_keyword(keywords::Unsafe)
7165 && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
7166 // CONST FUNCTION ITEM
7167 let unsafety = self.parse_unsafety();
7169 let (ident, item_, extra_attrs) =
7170 self.parse_item_fn(unsafety,
7172 respan(const_span, Constness::Const),
7174 let prev_span = self.prev_span;
7175 let item = self.mk_item(lo.to(prev_span),
7179 maybe_append(attrs, extra_attrs));
7180 return Ok(Some(item));
7184 if self.eat_keyword(keywords::Mut) {
7185 let prev_span = self.prev_span;
7186 self.diagnostic().struct_span_err(prev_span, "const globals cannot be mutable")
7187 .help("did you mean to declare a static?")
7190 let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
7191 let prev_span = self.prev_span;
7192 let item = self.mk_item(lo.to(prev_span),
7196 maybe_append(attrs, extra_attrs));
7197 return Ok(Some(item));
7200 // `unsafe async fn` or `async fn`
7202 self.check_keyword(keywords::Unsafe) &&
7203 self.look_ahead(1, |t| t.is_keyword(keywords::Async))
7205 self.check_keyword(keywords::Async) &&
7206 self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
7209 // ASYNC FUNCTION ITEM
7210 let unsafety = self.parse_unsafety();
7211 self.expect_keyword(keywords::Async)?;
7212 self.expect_keyword(keywords::Fn)?;
7213 let fn_span = self.prev_span;
7214 let (ident, item_, extra_attrs) =
7215 self.parse_item_fn(unsafety,
7217 closure_id: ast::DUMMY_NODE_ID,
7218 return_impl_trait_id: ast::DUMMY_NODE_ID,
7220 respan(fn_span, Constness::NotConst),
7222 let prev_span = self.prev_span;
7223 let item = self.mk_item(lo.to(prev_span),
7227 maybe_append(attrs, extra_attrs));
7228 return Ok(Some(item));
7230 if self.check_keyword(keywords::Unsafe) &&
7231 (self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) ||
7232 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)))
7234 // UNSAFE TRAIT ITEM
7235 self.bump(); // `unsafe`
7236 let is_auto = if self.eat_keyword(keywords::Trait) {
7239 self.expect_keyword(keywords::Auto)?;
7240 self.expect_keyword(keywords::Trait)?;
7243 let (ident, item_, extra_attrs) =
7244 self.parse_item_trait(is_auto, Unsafety::Unsafe)?;
7245 let prev_span = self.prev_span;
7246 let item = self.mk_item(lo.to(prev_span),
7250 maybe_append(attrs, extra_attrs));
7251 return Ok(Some(item));
7253 if self.check_keyword(keywords::Impl) ||
7254 self.check_keyword(keywords::Unsafe) &&
7255 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7256 self.check_keyword(keywords::Default) &&
7257 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7258 self.check_keyword(keywords::Default) &&
7259 self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) {
7261 let defaultness = self.parse_defaultness();
7262 let unsafety = self.parse_unsafety();
7263 self.expect_keyword(keywords::Impl)?;
7264 let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?;
7265 let span = lo.to(self.prev_span);
7266 return Ok(Some(self.mk_item(span, ident, item, visibility,
7267 maybe_append(attrs, extra_attrs))));
7269 if self.check_keyword(keywords::Fn) {
7272 let fn_span = self.prev_span;
7273 let (ident, item_, extra_attrs) =
7274 self.parse_item_fn(Unsafety::Normal,
7276 respan(fn_span, Constness::NotConst),
7278 let prev_span = self.prev_span;
7279 let item = self.mk_item(lo.to(prev_span),
7283 maybe_append(attrs, extra_attrs));
7284 return Ok(Some(item));
7286 if self.check_keyword(keywords::Unsafe)
7287 && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
7288 // UNSAFE FUNCTION ITEM
7289 self.bump(); // `unsafe`
7290 // `{` is also expected after `unsafe`, in case of error, include it in the diagnostic
7291 self.check(&token::OpenDelim(token::Brace));
7292 let abi = if self.eat_keyword(keywords::Extern) {
7293 self.parse_opt_abi()?.unwrap_or(Abi::C)
7297 self.expect_keyword(keywords::Fn)?;
7298 let fn_span = self.prev_span;
7299 let (ident, item_, extra_attrs) =
7300 self.parse_item_fn(Unsafety::Unsafe,
7302 respan(fn_span, Constness::NotConst),
7304 let prev_span = self.prev_span;
7305 let item = self.mk_item(lo.to(prev_span),
7309 maybe_append(attrs, extra_attrs));
7310 return Ok(Some(item));
7312 if self.eat_keyword(keywords::Mod) {
7314 let (ident, item_, extra_attrs) =
7315 self.parse_item_mod(&attrs[..])?;
7316 let prev_span = self.prev_span;
7317 let item = self.mk_item(lo.to(prev_span),
7321 maybe_append(attrs, extra_attrs));
7322 return Ok(Some(item));
7324 if let Some(type_) = self.eat_type() {
7325 let (ident, alias, generics) = type_?;
7327 let item_ = match alias {
7328 AliasKind::Weak(ty) => ItemKind::Ty(ty, generics),
7329 AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics),
7331 let prev_span = self.prev_span;
7332 let item = self.mk_item(lo.to(prev_span),
7337 return Ok(Some(item));
7339 if self.eat_keyword(keywords::Enum) {
7341 let (ident, item_, extra_attrs) = self.parse_item_enum()?;
7342 let prev_span = self.prev_span;
7343 let item = self.mk_item(lo.to(prev_span),
7347 maybe_append(attrs, extra_attrs));
7348 return Ok(Some(item));
7350 if self.check_keyword(keywords::Trait)
7351 || (self.check_keyword(keywords::Auto)
7352 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
7354 let is_auto = if self.eat_keyword(keywords::Trait) {
7357 self.expect_keyword(keywords::Auto)?;
7358 self.expect_keyword(keywords::Trait)?;
7362 let (ident, item_, extra_attrs) =
7363 self.parse_item_trait(is_auto, Unsafety::Normal)?;
7364 let prev_span = self.prev_span;
7365 let item = self.mk_item(lo.to(prev_span),
7369 maybe_append(attrs, extra_attrs));
7370 return Ok(Some(item));
7372 if self.eat_keyword(keywords::Struct) {
7374 let (ident, item_, extra_attrs) = self.parse_item_struct()?;
7375 let prev_span = self.prev_span;
7376 let item = self.mk_item(lo.to(prev_span),
7380 maybe_append(attrs, extra_attrs));
7381 return Ok(Some(item));
7383 if self.is_union_item() {
7386 let (ident, item_, extra_attrs) = self.parse_item_union()?;
7387 let prev_span = self.prev_span;
7388 let item = self.mk_item(lo.to(prev_span),
7392 maybe_append(attrs, extra_attrs));
7393 return Ok(Some(item));
7395 if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, lo)? {
7396 return Ok(Some(macro_def));
7399 // Verify whether we have encountered a struct or method definition where the user forgot to
7400 // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
7401 if visibility.node.is_pub() &&
7402 self.check_ident() &&
7403 self.look_ahead(1, |t| *t != token::Not)
7405 // Space between `pub` keyword and the identifier
7408 // ^^^ `sp` points here
7409 let sp = self.prev_span.between(self.span);
7410 let full_sp = self.prev_span.to(self.span);
7411 let ident_sp = self.span;
7412 if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
7413 // possible public struct definition where `struct` was forgotten
7414 let ident = self.parse_ident().unwrap();
7415 let msg = format!("add `struct` here to parse `{}` as a public struct",
7417 let mut err = self.diagnostic()
7418 .struct_span_err(sp, "missing `struct` for struct definition");
7419 err.span_suggestion_short_with_applicability(
7420 sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
7423 } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
7424 let ident = self.parse_ident().unwrap();
7426 let kw_name = if let Ok(Some(_)) = self.parse_self_arg() {
7431 self.consume_block(token::Paren);
7432 let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) {
7433 self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]);
7435 ("fn", kw_name, false)
7436 } else if self.check(&token::OpenDelim(token::Brace)) {
7438 ("fn", kw_name, false)
7439 } else if self.check(&token::Colon) {
7443 ("fn` or `struct", "function or struct", true)
7445 self.consume_block(token::Brace);
7447 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7448 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7450 let suggestion = format!("add `{}` here to parse `{}` as a public {}",
7454 err.span_suggestion_short_with_applicability(
7455 sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
7458 if let Ok(snippet) = self.sess.source_map().span_to_snippet(ident_sp) {
7459 err.span_suggestion_with_applicability(
7461 "if you meant to call a macro, try",
7462 format!("{}!", snippet),
7463 // this is the `ambiguous` conditional branch
7464 Applicability::MaybeIncorrect
7467 err.help("if you meant to call a macro, remove the `pub` \
7468 and add a trailing `!` after the identifier");
7472 } else if self.look_ahead(1, |t| *t == token::Lt) {
7473 let ident = self.parse_ident().unwrap();
7474 self.eat_to_tokens(&[&token::Gt]);
7476 let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) {
7477 if let Ok(Some(_)) = self.parse_self_arg() {
7478 ("fn", "method", false)
7480 ("fn", "function", false)
7482 } else if self.check(&token::OpenDelim(token::Brace)) {
7483 ("struct", "struct", false)
7485 ("fn` or `struct", "function or struct", true)
7487 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7488 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7490 err.span_suggestion_short_with_applicability(
7492 &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name),
7493 format!(" {} ", kw),
7494 Applicability::MachineApplicable,
7500 self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, visibility)
7503 /// Parse a foreign item.
7504 crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> {
7505 maybe_whole!(self, NtForeignItem, |ni| ni);
7507 let attrs = self.parse_outer_attributes()?;
7509 let visibility = self.parse_visibility(false)?;
7511 // FOREIGN STATIC ITEM
7512 // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
7513 if self.check_keyword(keywords::Static) || self.token.is_keyword(keywords::Const) {
7514 if self.token.is_keyword(keywords::Const) {
7516 .struct_span_err(self.span, "extern items cannot be `const`")
7517 .span_suggestion_with_applicability(
7519 "try using a static value",
7520 "static".to_owned(),
7521 Applicability::MachineApplicable
7524 self.bump(); // `static` or `const`
7525 return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
7527 // FOREIGN FUNCTION ITEM
7528 if self.check_keyword(keywords::Fn) {
7529 return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?);
7531 // FOREIGN TYPE ITEM
7532 if self.check_keyword(keywords::Type) {
7533 return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
7536 match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
7540 ident: keywords::Invalid.ident(),
7541 span: lo.to(self.prev_span),
7542 id: ast::DUMMY_NODE_ID,
7545 node: ForeignItemKind::Macro(mac),
7550 if !attrs.is_empty() {
7551 self.expected_item_err(&attrs);
7559 /// This is the fall-through for parsing items.
7560 fn parse_macro_use_or_failure(
7562 attrs: Vec<Attribute> ,
7563 macros_allowed: bool,
7564 attributes_allowed: bool,
7566 visibility: Visibility
7567 ) -> PResult<'a, Option<P<Item>>> {
7568 if macros_allowed && self.token.is_path_start() {
7569 // MACRO INVOCATION ITEM
7571 let prev_span = self.prev_span;
7572 self.complain_if_pub_macro(&visibility.node, prev_span);
7574 let mac_lo = self.span;
7577 let pth = self.parse_path(PathStyle::Mod)?;
7578 self.expect(&token::Not)?;
7580 // a 'special' identifier (like what `macro_rules!` uses)
7581 // is optional. We should eventually unify invoc syntax
7583 let id = if self.token.is_ident() {
7586 keywords::Invalid.ident() // no special identifier
7588 // eat a matched-delimiter token tree:
7589 let (delim, tts) = self.expect_delimited_token_tree()?;
7590 if delim != MacDelimiter::Brace {
7591 if !self.eat(&token::Semi) {
7592 self.span_err(self.prev_span,
7593 "macros that expand to items must either \
7594 be surrounded with braces or followed by \
7599 let hi = self.prev_span;
7600 let mac = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim });
7601 let item = self.mk_item(lo.to(hi), id, ItemKind::Mac(mac), visibility, attrs);
7602 return Ok(Some(item));
7605 // FAILURE TO PARSE ITEM
7606 match visibility.node {
7607 VisibilityKind::Inherited => {}
7609 return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
7613 if !attributes_allowed && !attrs.is_empty() {
7614 self.expected_item_err(&attrs);
7619 /// Parse a macro invocation inside a `trait`, `impl` or `extern` block
7620 fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
7621 at_end: &mut bool) -> PResult<'a, Option<Mac>>
7623 if self.token.is_path_start() && !self.is_extern_non_path() {
7624 let prev_span = self.prev_span;
7626 let pth = self.parse_path(PathStyle::Mod)?;
7628 if pth.segments.len() == 1 {
7629 if !self.eat(&token::Not) {
7630 return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
7633 self.expect(&token::Not)?;
7636 if let Some(vis) = vis {
7637 self.complain_if_pub_macro(&vis.node, prev_span);
7642 // eat a matched-delimiter token tree:
7643 let (delim, tts) = self.expect_delimited_token_tree()?;
7644 if delim != MacDelimiter::Brace {
7645 self.expect(&token::Semi)?
7648 Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim })))
7654 fn collect_tokens<F, R>(&mut self, f: F) -> PResult<'a, (R, TokenStream)>
7655 where F: FnOnce(&mut Self) -> PResult<'a, R>
7657 // Record all tokens we parse when parsing this item.
7658 let mut tokens = Vec::new();
7659 let prev_collecting = match self.token_cursor.frame.last_token {
7660 LastToken::Collecting(ref mut list) => {
7661 Some(mem::replace(list, Vec::new()))
7663 LastToken::Was(ref mut last) => {
7664 tokens.extend(last.take());
7668 self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
7669 let prev = self.token_cursor.stack.len();
7671 let last_token = if self.token_cursor.stack.len() == prev {
7672 &mut self.token_cursor.frame.last_token
7674 &mut self.token_cursor.stack[prev].last_token
7677 // Pull our the toekns that we've collected from the call to `f` above
7678 let mut collected_tokens = match *last_token {
7679 LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()),
7680 LastToken::Was(_) => panic!("our vector went away?"),
7683 // If we're not at EOF our current token wasn't actually consumed by
7684 // `f`, but it'll still be in our list that we pulled out. In that case
7686 let extra_token = if self.token != token::Eof {
7687 collected_tokens.pop()
7692 // If we were previously collecting tokens, then this was a recursive
7693 // call. In that case we need to record all the tokens we collected in
7694 // our parent list as well. To do that we push a clone of our stream
7695 // onto the previous list.
7696 let stream = collected_tokens.into_iter().collect::<TokenStream>();
7697 match prev_collecting {
7699 list.push(stream.clone());
7700 list.extend(extra_token);
7701 *last_token = LastToken::Collecting(list);
7704 *last_token = LastToken::Was(extra_token);
7711 pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
7712 let attrs = self.parse_outer_attributes()?;
7713 self.parse_item_(attrs, true, false)
7717 fn is_import_coupler(&mut self) -> bool {
7718 self.check(&token::ModSep) &&
7719 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
7720 *t == token::BinOp(token::Star))
7725 /// USE_TREE = [`::`] `*` |
7726 /// [`::`] `{` USE_TREE_LIST `}` |
7728 /// PATH `::` `{` USE_TREE_LIST `}` |
7729 /// PATH [`as` IDENT]
7730 fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
7733 let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
7734 let kind = if self.check(&token::OpenDelim(token::Brace)) ||
7735 self.check(&token::BinOp(token::Star)) ||
7736 self.is_import_coupler() {
7737 // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
7738 let mod_sep_ctxt = self.span.ctxt();
7739 if self.eat(&token::ModSep) {
7740 prefix.segments.push(
7741 PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
7745 if self.eat(&token::BinOp(token::Star)) {
7748 UseTreeKind::Nested(self.parse_use_tree_list()?)
7751 // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
7752 prefix = self.parse_path(PathStyle::Mod)?;
7754 if self.eat(&token::ModSep) {
7755 if self.eat(&token::BinOp(token::Star)) {
7758 UseTreeKind::Nested(self.parse_use_tree_list()?)
7761 UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID)
7765 Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
7768 /// Parse UseTreeKind::Nested(list)
7770 /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
7771 fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
7772 self.parse_unspanned_seq(&token::OpenDelim(token::Brace),
7773 &token::CloseDelim(token::Brace),
7774 SeqSep::trailing_allowed(token::Comma), |this| {
7775 Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID))
7779 fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
7780 if self.eat_keyword(keywords::As) {
7781 self.parse_ident_or_underscore().map(Some)
7787 /// Parses a source module as a crate. This is the main
7788 /// entry point for the parser.
7789 pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
7792 attrs: self.parse_inner_attributes()?,
7793 module: self.parse_mod_items(&token::Eof, lo)?,
7794 span: lo.to(self.span),
7798 pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
7799 let ret = match self.token {
7800 token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf),
7801 token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf),
7808 pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
7809 match self.parse_optional_str() {
7810 Some((s, style, suf)) => {
7811 let sp = self.prev_span;
7812 self.expect_no_suffix(sp, "string literal", suf);
7816 let msg = "expected string literal";
7817 let mut err = self.fatal(msg);
7818 err.span_label(self.span, msg);