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 Some(token_descr) = self.token_descr() {
802 err.span_label(self.span, format!("expected identifier, found {}", token_descr));
804 err.span_label(self.span, "expected identifier");
805 if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) {
806 err.span_suggestion_with_applicability(
810 Applicability::MachineApplicable,
817 pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
818 self.parse_ident_common(true)
821 fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
823 token::Ident(ident, _) => {
824 if self.token.is_reserved_ident() {
825 let mut err = self.expected_ident_found();
832 let span = self.span;
834 Ok(Ident::new(ident.name, span))
837 Err(if self.prev_token_kind == PrevTokenKind::DocComment {
838 self.span_fatal_err(self.prev_span, Error::UselessDocComment)
840 self.expected_ident_found()
846 /// Check if the next token is `tok`, and return `true` if so.
848 /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
850 crate fn check(&mut self, tok: &token::Token) -> bool {
851 let is_present = self.token == *tok;
852 if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
856 /// Consume token 'tok' if it exists. Returns true if the given
857 /// token was present, false otherwise.
858 pub fn eat(&mut self, tok: &token::Token) -> bool {
859 let is_present = self.check(tok);
860 if is_present { self.bump() }
864 fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
865 self.expected_tokens.push(TokenType::Keyword(kw));
866 self.token.is_keyword(kw)
869 /// If the next token is the given keyword, eat it and return
870 /// true. Otherwise, return false.
871 pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
872 if self.check_keyword(kw) {
880 fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
881 if self.token.is_keyword(kw) {
889 /// If the given word is not a keyword, signal an error.
890 /// If the next token is not the given word, signal an error.
891 /// Otherwise, eat it.
892 fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> {
893 if !self.eat_keyword(kw) {
900 fn check_ident(&mut self) -> bool {
901 if self.token.is_ident() {
904 self.expected_tokens.push(TokenType::Ident);
909 fn check_path(&mut self) -> bool {
910 if self.token.is_path_start() {
913 self.expected_tokens.push(TokenType::Path);
918 fn check_type(&mut self) -> bool {
919 if self.token.can_begin_type() {
922 self.expected_tokens.push(TokenType::Type);
927 /// Expect and consume a `+`. if `+=` is seen, replace it with a `=`
928 /// and continue. If a `+` is not seen, return false.
930 /// This is using when token splitting += into +.
931 /// See issue 47856 for an example of when this may occur.
932 fn eat_plus(&mut self) -> bool {
933 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
935 token::BinOp(token::Plus) => {
939 token::BinOpEq(token::Plus) => {
940 let span = self.span.with_lo(self.span.lo() + BytePos(1));
941 self.bump_with(token::Eq, span);
949 /// Checks to see if the next token is either `+` or `+=`.
950 /// Otherwise returns false.
951 fn check_plus(&mut self) -> bool {
952 if self.token.is_like_plus() {
956 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
961 /// Expect and consume an `&`. If `&&` is seen, replace it with a single
962 /// `&` and continue. If an `&` is not seen, signal an error.
963 fn expect_and(&mut self) -> PResult<'a, ()> {
964 self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
966 token::BinOp(token::And) => {
971 let span = self.span.with_lo(self.span.lo() + BytePos(1));
972 Ok(self.bump_with(token::BinOp(token::And), span))
974 _ => self.unexpected()
978 /// Expect and consume an `|`. If `||` is seen, replace it with a single
979 /// `|` and continue. If an `|` is not seen, signal an error.
980 fn expect_or(&mut self) -> PResult<'a, ()> {
981 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or)));
983 token::BinOp(token::Or) => {
988 let span = self.span.with_lo(self.span.lo() + BytePos(1));
989 Ok(self.bump_with(token::BinOp(token::Or), span))
991 _ => self.unexpected()
995 fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
997 None => {/* everything ok */}
999 let text = suf.as_str();
1000 if text.is_empty() {
1001 self.span_bug(sp, "found empty literal suffix in Some")
1003 self.span_err(sp, &format!("{} with a suffix is invalid", kind));
1008 /// Attempt to consume a `<`. If `<<` is seen, replace it with a single
1009 /// `<` and continue. If a `<` is not seen, return false.
1011 /// This is meant to be used when parsing generics on a path to get the
1013 fn eat_lt(&mut self) -> bool {
1014 self.expected_tokens.push(TokenType::Token(token::Lt));
1020 token::BinOp(token::Shl) => {
1021 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1022 self.bump_with(token::Lt, span);
1029 fn expect_lt(&mut self) -> PResult<'a, ()> {
1037 /// Expect and consume a GT. if a >> is seen, replace it
1038 /// with a single > and continue. If a GT is not seen,
1039 /// signal an error.
1040 fn expect_gt(&mut self) -> PResult<'a, ()> {
1041 self.expected_tokens.push(TokenType::Token(token::Gt));
1047 token::BinOp(token::Shr) => {
1048 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1049 Ok(self.bump_with(token::Gt, span))
1051 token::BinOpEq(token::Shr) => {
1052 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1053 Ok(self.bump_with(token::Ge, span))
1056 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1057 Ok(self.bump_with(token::Eq, span))
1059 _ => self.unexpected()
1063 /// Eat and discard tokens until one of `kets` is encountered. Respects token trees,
1064 /// passes through any errors encountered. Used for error recovery.
1065 fn eat_to_tokens(&mut self, kets: &[&token::Token]) {
1066 let handler = self.diagnostic();
1068 if let Err(ref mut err) = self.parse_seq_to_before_tokens(kets,
1070 TokenExpectType::Expect,
1071 |p| Ok(p.parse_token_tree())) {
1072 handler.cancel(err);
1076 /// Parse a sequence, including the closing delimiter. The function
1077 /// f must consume tokens until reaching the next separator or
1078 /// closing bracket.
1079 pub fn parse_seq_to_end<T, F>(&mut self,
1083 -> PResult<'a, Vec<T>> where
1084 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1086 let val = self.parse_seq_to_before_end(ket, sep, f)?;
1091 /// Parse a sequence, not including the closing delimiter. The function
1092 /// f must consume tokens until reaching the next separator or
1093 /// closing bracket.
1094 pub fn parse_seq_to_before_end<T, F>(&mut self,
1098 -> PResult<'a, Vec<T>>
1099 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1101 self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
1104 fn parse_seq_to_before_tokens<T, F>(
1106 kets: &[&token::Token],
1108 expect: TokenExpectType,
1110 ) -> PResult<'a, Vec<T>>
1111 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1113 let mut first: bool = true;
1115 while !kets.iter().any(|k| {
1117 TokenExpectType::Expect => self.check(k),
1118 TokenExpectType::NoExpect => self.token == **k,
1122 token::CloseDelim(..) | token::Eof => break,
1125 if let Some(ref t) = sep.sep {
1129 if let Err(mut e) = self.expect(t) {
1130 // Attempt to keep parsing if it was a similar separator
1131 if let Some(ref tokens) = t.similar_tokens() {
1132 if tokens.contains(&self.token) {
1137 // Attempt to keep parsing if it was an omitted separator
1151 if sep.trailing_sep_allowed && kets.iter().any(|k| {
1153 TokenExpectType::Expect => self.check(k),
1154 TokenExpectType::NoExpect => self.token == **k,
1167 /// Parse a sequence, including the closing delimiter. The function
1168 /// f must consume tokens until reaching the next separator or
1169 /// closing bracket.
1170 fn parse_unspanned_seq<T, F>(&mut self,
1175 -> PResult<'a, Vec<T>> where
1176 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1179 let result = self.parse_seq_to_before_end(ket, sep, f)?;
1184 /// Advance the parser by one token
1185 pub fn bump(&mut self) {
1186 if self.prev_token_kind == PrevTokenKind::Eof {
1187 // Bumping after EOF is a bad sign, usually an infinite loop.
1188 self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
1191 self.prev_span = self.meta_var_span.take().unwrap_or(self.span);
1193 // Record last token kind for possible error recovery.
1194 self.prev_token_kind = match self.token {
1195 token::DocComment(..) => PrevTokenKind::DocComment,
1196 token::Comma => PrevTokenKind::Comma,
1197 token::BinOp(token::Plus) => PrevTokenKind::Plus,
1198 token::Interpolated(..) => PrevTokenKind::Interpolated,
1199 token::Eof => PrevTokenKind::Eof,
1200 token::Ident(..) => PrevTokenKind::Ident,
1201 _ => PrevTokenKind::Other,
1204 let next = self.next_tok();
1205 self.span = next.sp;
1206 self.token = next.tok;
1207 self.expected_tokens.clear();
1208 // check after each token
1209 self.process_potential_macro_variable();
1212 /// Advance the parser using provided token as a next one. Use this when
1213 /// consuming a part of a token. For example a single `<` from `<<`.
1214 fn bump_with(&mut self, next: token::Token, span: Span) {
1215 self.prev_span = self.span.with_hi(span.lo());
1216 // It would be incorrect to record the kind of the current token, but
1217 // fortunately for tokens currently using `bump_with`, the
1218 // prev_token_kind will be of no use anyway.
1219 self.prev_token_kind = PrevTokenKind::Other;
1222 self.expected_tokens.clear();
1225 pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where
1226 F: FnOnce(&token::Token) -> R,
1229 return f(&self.token)
1232 f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1233 Some(tree) => match tree {
1234 TokenTree::Token(_, tok) => tok,
1235 TokenTree::Delimited(_, delim, _) => token::OpenDelim(delim),
1237 None => token::CloseDelim(self.token_cursor.frame.delim),
1241 fn look_ahead_span(&self, dist: usize) -> Span {
1246 match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1247 Some(TokenTree::Token(span, _)) => span,
1248 Some(TokenTree::Delimited(span, ..)) => span.entire(),
1249 None => self.look_ahead_span(dist - 1),
1252 pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
1253 self.sess.span_diagnostic.struct_span_fatal(self.span, m)
1255 pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1256 self.sess.span_diagnostic.struct_span_fatal(sp, m)
1258 fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> {
1259 err.span_err(sp, self.diagnostic())
1261 fn bug(&self, m: &str) -> ! {
1262 self.sess.span_diagnostic.span_bug(self.span, m)
1264 fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
1265 self.sess.span_diagnostic.span_err(sp, m)
1267 fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1268 self.sess.span_diagnostic.struct_span_err(sp, m)
1270 crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
1271 self.sess.span_diagnostic.span_bug(sp, m)
1273 crate fn abort_if_errors(&self) {
1274 self.sess.span_diagnostic.abort_if_errors();
1277 fn cancel(&self, err: &mut DiagnosticBuilder) {
1278 self.sess.span_diagnostic.cancel(err)
1281 crate fn diagnostic(&self) -> &'a errors::Handler {
1282 &self.sess.span_diagnostic
1285 /// Is the current token one of the keywords that signals a bare function
1287 fn token_is_bare_fn_keyword(&mut self) -> bool {
1288 self.check_keyword(keywords::Fn) ||
1289 self.check_keyword(keywords::Unsafe) ||
1290 self.check_keyword(keywords::Extern) && self.is_extern_non_path()
1293 /// parse a `TyKind::BareFn` type:
1294 fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
1297 [unsafe] [extern "ABI"] fn (S) -> T
1307 let unsafety = self.parse_unsafety();
1308 let abi = if self.eat_keyword(keywords::Extern) {
1309 self.parse_opt_abi()?.unwrap_or(Abi::C)
1314 self.expect_keyword(keywords::Fn)?;
1315 let (inputs, variadic) = self.parse_fn_args(false, true)?;
1316 let ret_ty = self.parse_ret_ty(false)?;
1317 let decl = P(FnDecl {
1322 Ok(TyKind::BareFn(P(BareFnTy {
1330 /// Parse asyncness: `async` or nothing
1331 fn parse_asyncness(&mut self) -> IsAsync {
1332 if self.eat_keyword(keywords::Async) {
1334 closure_id: ast::DUMMY_NODE_ID,
1335 return_impl_trait_id: ast::DUMMY_NODE_ID,
1342 /// Parse unsafety: `unsafe` or nothing.
1343 fn parse_unsafety(&mut self) -> Unsafety {
1344 if self.eat_keyword(keywords::Unsafe) {
1351 /// Parse the items in a trait declaration
1352 pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> {
1353 maybe_whole!(self, NtTraitItem, |x| x);
1354 let attrs = self.parse_outer_attributes()?;
1355 let (mut item, tokens) = self.collect_tokens(|this| {
1356 this.parse_trait_item_(at_end, attrs)
1358 // See `parse_item` for why this clause is here.
1359 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
1360 item.tokens = Some(tokens);
1365 fn parse_trait_item_(&mut self,
1367 mut attrs: Vec<Attribute>) -> PResult<'a, TraitItem> {
1370 let (name, node, generics) = if self.eat_keyword(keywords::Type) {
1371 self.parse_trait_item_assoc_ty()?
1372 } else if self.is_const_item() {
1373 self.expect_keyword(keywords::Const)?;
1374 let ident = self.parse_ident()?;
1375 self.expect(&token::Colon)?;
1376 let ty = self.parse_ty()?;
1377 let default = if self.eat(&token::Eq) {
1378 let expr = self.parse_expr()?;
1379 self.expect(&token::Semi)?;
1382 self.expect(&token::Semi)?;
1385 (ident, TraitItemKind::Const(ty, default), ast::Generics::default())
1386 } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
1387 // trait item macro.
1388 (keywords::Invalid.ident(), ast::TraitItemKind::Macro(mac), ast::Generics::default())
1390 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
1392 let ident = self.parse_ident()?;
1393 let mut generics = self.parse_generics()?;
1395 let d = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
1396 // This is somewhat dubious; We don't want to allow
1397 // argument names to be left off if there is a
1400 // We don't allow argument names to be left off in edition 2018.
1401 p.parse_arg_general(p.span.rust_2018(), true)
1403 generics.where_clause = self.parse_where_clause()?;
1405 let sig = ast::MethodSig {
1415 let body = match self.token {
1419 debug!("parse_trait_methods(): parsing required method");
1422 token::OpenDelim(token::Brace) => {
1423 debug!("parse_trait_methods(): parsing provided method");
1425 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1426 attrs.extend(inner_attrs.iter().cloned());
1429 token::Interpolated(ref nt) => {
1431 token::NtBlock(..) => {
1433 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1434 attrs.extend(inner_attrs.iter().cloned());
1438 let token_str = self.this_token_descr();
1439 let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
1441 err.span_label(self.span, "expected `;` or `{`");
1447 let token_str = self.this_token_descr();
1448 let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
1450 err.span_label(self.span, "expected `;` or `{`");
1454 (ident, ast::TraitItemKind::Method(sig, body), generics)
1458 id: ast::DUMMY_NODE_ID,
1463 span: lo.to(self.prev_span),
1468 /// Parse optional return type [ -> TY ] in function decl
1469 fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> {
1470 if self.eat(&token::RArrow) {
1471 Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true)?))
1473 Ok(FunctionRetTy::Default(self.span.shrink_to_lo()))
1478 pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
1479 self.parse_ty_common(true, true)
1482 /// Parse a type in restricted contexts where `+` is not permitted.
1483 /// Example 1: `&'a TYPE`
1484 /// `+` is prohibited to maintain operator priority (P(+) < P(&)).
1485 /// Example 2: `value1 as TYPE + value2`
1486 /// `+` is prohibited to avoid interactions with expression grammar.
1487 fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
1488 self.parse_ty_common(false, true)
1491 fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool)
1492 -> PResult<'a, P<Ty>> {
1493 maybe_whole!(self, NtTy, |x| x);
1496 let mut impl_dyn_multi = false;
1497 let node = if self.eat(&token::OpenDelim(token::Paren)) {
1498 // `(TYPE)` is a parenthesized type.
1499 // `(TYPE,)` is a tuple with a single field of type TYPE.
1500 let mut ts = vec![];
1501 let mut last_comma = false;
1502 while self.token != token::CloseDelim(token::Paren) {
1503 ts.push(self.parse_ty()?);
1504 if self.eat(&token::Comma) {
1511 let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
1512 self.expect(&token::CloseDelim(token::Paren))?;
1514 if ts.len() == 1 && !last_comma {
1515 let ty = ts.into_iter().nth(0).unwrap().into_inner();
1516 let maybe_bounds = allow_plus && self.token.is_like_plus();
1518 // `(TY_BOUND_NOPAREN) + BOUND + ...`.
1519 TyKind::Path(None, ref path) if maybe_bounds => {
1520 self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
1522 TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
1523 if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
1524 let path = match bounds[0] {
1525 GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
1526 GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
1528 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1531 _ => TyKind::Paren(P(ty))
1536 } else if self.eat(&token::Not) {
1539 } else if self.eat(&token::BinOp(token::Star)) {
1541 TyKind::Ptr(self.parse_ptr()?)
1542 } else if self.eat(&token::OpenDelim(token::Bracket)) {
1544 let t = self.parse_ty()?;
1545 // Parse optional `; EXPR` in `[TYPE; EXPR]`
1546 let t = match self.maybe_parse_fixed_length_of_vec()? {
1547 None => TyKind::Slice(t),
1548 Some(length) => TyKind::Array(t, AnonConst {
1549 id: ast::DUMMY_NODE_ID,
1553 self.expect(&token::CloseDelim(token::Bracket))?;
1555 } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
1558 self.parse_borrowed_pointee()?
1559 } else if self.eat_keyword_noexpect(keywords::Typeof) {
1561 // In order to not be ambiguous, the type must be surrounded by parens.
1562 self.expect(&token::OpenDelim(token::Paren))?;
1564 id: ast::DUMMY_NODE_ID,
1565 value: self.parse_expr()?,
1567 self.expect(&token::CloseDelim(token::Paren))?;
1569 } else if self.eat_keyword(keywords::Underscore) {
1570 // A type to be inferred `_`
1572 } else if self.token_is_bare_fn_keyword() {
1573 // Function pointer type
1574 self.parse_ty_bare_fn(Vec::new())?
1575 } else if self.check_keyword(keywords::For) {
1576 // Function pointer type or bound list (trait object type) starting with a poly-trait.
1577 // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
1578 // `for<'lt> Trait1<'lt> + Trait2 + 'a`
1580 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
1581 if self.token_is_bare_fn_keyword() {
1582 self.parse_ty_bare_fn(lifetime_defs)?
1584 let path = self.parse_path(PathStyle::Type)?;
1585 let parse_plus = allow_plus && self.check_plus();
1586 self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
1588 } else if self.eat_keyword(keywords::Impl) {
1589 // Always parse bounds greedily for better error recovery.
1590 let bounds = self.parse_generic_bounds()?;
1591 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1592 TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
1593 } else if self.check_keyword(keywords::Dyn) &&
1594 (self.span.rust_2018() ||
1595 self.look_ahead(1, |t| t.can_begin_bound() &&
1596 !can_continue_type_after_non_fn_ident(t))) {
1597 self.bump(); // `dyn`
1598 // Always parse bounds greedily for better error recovery.
1599 let bounds = self.parse_generic_bounds()?;
1600 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1601 TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
1602 } else if self.check(&token::Question) ||
1603 self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
1604 // Bound list (trait object type)
1605 TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus)?,
1606 TraitObjectSyntax::None)
1607 } else if self.eat_lt() {
1609 let (qself, path) = self.parse_qpath(PathStyle::Type)?;
1610 TyKind::Path(Some(qself), path)
1611 } else if self.token.is_path_start() {
1613 let path = self.parse_path(PathStyle::Type)?;
1614 if self.eat(&token::Not) {
1615 // Macro invocation in type position
1616 let (delim, tts) = self.expect_delimited_token_tree()?;
1617 let node = Mac_ { path, tts, delim };
1618 TyKind::Mac(respan(lo.to(self.prev_span), node))
1620 // Just a type path or bound list (trait object type) starting with a trait.
1622 // `Trait1 + Trait2 + 'a`
1623 if allow_plus && self.check_plus() {
1624 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1626 TyKind::Path(None, path)
1630 let msg = format!("expected type, found {}", self.this_token_descr());
1631 return Err(self.fatal(&msg));
1634 let span = lo.to(self.prev_span);
1635 let ty = Ty { node, span, id: ast::DUMMY_NODE_ID };
1637 // Try to recover from use of `+` with incorrect priority.
1638 self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
1639 self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
1640 let ty = self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)?;
1645 fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
1646 lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
1647 let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));
1648 let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
1650 self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
1651 bounds.append(&mut self.parse_generic_bounds()?);
1653 Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
1656 fn maybe_report_ambiguous_plus(&mut self, allow_plus: bool, impl_dyn_multi: bool, ty: &Ty) {
1657 if !allow_plus && impl_dyn_multi {
1658 let sum_with_parens = format!("({})", pprust::ty_to_string(&ty));
1659 self.struct_span_err(ty.span, "ambiguous `+` in a type")
1660 .span_suggestion_with_applicability(
1662 "use parentheses to disambiguate",
1664 Applicability::MachineApplicable
1669 fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> {
1670 // Do not add `+` to expected tokens.
1671 if !allow_plus || !self.token.is_like_plus() {
1676 let bounds = self.parse_generic_bounds()?;
1677 let sum_span = ty.span.to(self.prev_span);
1679 let mut err = struct_span_err!(self.sess.span_diagnostic, sum_span, E0178,
1680 "expected a path on the left-hand side of `+`, not `{}`", pprust::ty_to_string(ty));
1683 TyKind::Rptr(ref lifetime, ref mut_ty) => {
1684 let sum_with_parens = pprust::to_string(|s| {
1685 use print::pprust::PrintState;
1688 s.print_opt_lifetime(lifetime)?;
1689 s.print_mutability(mut_ty.mutbl)?;
1691 s.print_type(&mut_ty.ty)?;
1692 s.print_type_bounds(" +", &bounds)?;
1695 err.span_suggestion_with_applicability(
1697 "try adding parentheses",
1699 Applicability::MachineApplicable
1702 TyKind::Ptr(..) | TyKind::BareFn(..) => {
1703 err.span_label(sum_span, "perhaps you forgot parentheses?");
1706 err.span_label(sum_span, "expected a path");
1713 // Try to recover from associated item paths like `[T]::AssocItem`/`(T, U)::AssocItem`.
1714 fn maybe_recover_from_bad_qpath<T: RecoverQPath>(&mut self, base: T, allow_recovery: bool)
1716 // Do not add `::` to expected tokens.
1717 if !allow_recovery || self.token != token::ModSep {
1720 let ty = match base.to_ty() {
1722 None => return Ok(base),
1725 self.bump(); // `::`
1726 let mut segments = Vec::new();
1727 self.parse_path_segments(&mut segments, T::PATH_STYLE, true)?;
1729 let span = ty.span.to(self.prev_span);
1730 let path_span = span.to(span); // use an empty path since `position` == 0
1731 let recovered = base.to_recovered(
1732 Some(QSelf { ty, path_span, position: 0 }),
1733 ast::Path { segments, span },
1737 .struct_span_err(span, "missing angle brackets in associated item path")
1738 .span_suggestion_with_applicability( // this is a best-effort recovery
1739 span, "try", recovered.to_string(), Applicability::MaybeIncorrect
1745 fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
1746 let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
1747 let mutbl = self.parse_mutability();
1748 let ty = self.parse_ty_no_plus()?;
1749 return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl }));
1752 fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
1753 let mutbl = if self.eat_keyword(keywords::Mut) {
1755 } else if self.eat_keyword(keywords::Const) {
1756 Mutability::Immutable
1758 let span = self.prev_span;
1760 "expected mut or const in raw pointer type (use \
1761 `*mut T` or `*const T` as appropriate)");
1762 Mutability::Immutable
1764 let t = self.parse_ty_no_plus()?;
1765 Ok(MutTy { ty: t, mutbl: mutbl })
1768 fn is_named_argument(&mut self) -> bool {
1769 let offset = match self.token {
1770 token::Interpolated(ref nt) => match nt.0 {
1771 token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
1774 token::BinOp(token::And) | token::AndAnd => 1,
1775 _ if self.token.is_keyword(keywords::Mut) => 1,
1779 self.look_ahead(offset, |t| t.is_ident()) &&
1780 self.look_ahead(offset + 1, |t| t == &token::Colon)
1783 /// Skip unexpected attributes and doc comments in this position and emit an appropriate error.
1784 fn eat_incorrect_doc_comment(&mut self, applied_to: &str) {
1785 if let token::DocComment(_) = self.token {
1786 let mut err = self.diagnostic().struct_span_err(
1788 &format!("documentation comments cannot be applied to {}", applied_to),
1790 err.span_label(self.span, "doc comments are not allowed here");
1793 } else if self.token == token::Pound && self.look_ahead(1, |t| {
1794 *t == token::OpenDelim(token::Bracket)
1797 // Skip every token until next possible arg.
1798 while self.token != token::CloseDelim(token::Bracket) {
1801 let sp = lo.to(self.span);
1803 let mut err = self.diagnostic().struct_span_err(
1805 &format!("attributes cannot be applied to {}", applied_to),
1807 err.span_label(sp, "attributes are not allowed here");
1812 /// This version of parse arg doesn't necessarily require
1813 /// identifier names.
1814 fn parse_arg_general(&mut self, require_name: bool, is_trait_item: bool) -> PResult<'a, Arg> {
1815 maybe_whole!(self, NtArg, |x| x);
1817 if let Ok(Some(_)) = self.parse_self_arg() {
1818 let mut err = self.struct_span_err(self.prev_span,
1819 "unexpected `self` argument in function");
1820 err.span_label(self.prev_span,
1821 "`self` is only valid as the first argument of an associated function");
1825 let (pat, ty) = if require_name || self.is_named_argument() {
1826 debug!("parse_arg_general parse_pat (require_name:{})",
1828 self.eat_incorrect_doc_comment("method arguments");
1829 let pat = self.parse_pat(Some("argument name"))?;
1831 if let Err(mut err) = self.expect(&token::Colon) {
1832 // If we find a pattern followed by an identifier, it could be an (incorrect)
1833 // C-style parameter declaration.
1834 if self.check_ident() && self.look_ahead(1, |t| {
1835 *t == token::Comma || *t == token::CloseDelim(token::Paren)
1837 let ident = self.parse_ident().unwrap();
1838 let span = pat.span.with_hi(ident.span.hi());
1840 err.span_suggestion_with_applicability(
1842 "declare the type after the parameter binding",
1843 String::from("<identifier>: <type>"),
1844 Applicability::HasPlaceholders,
1846 } else if require_name && is_trait_item {
1847 if let PatKind::Ident(_, ident, _) = pat.node {
1848 err.span_suggestion_with_applicability(
1850 "explicitly ignore parameter",
1851 format!("_: {}", ident),
1852 Applicability::MachineApplicable,
1856 err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
1862 self.eat_incorrect_doc_comment("a method argument's type");
1863 (pat, self.parse_ty()?)
1865 debug!("parse_arg_general ident_to_pat");
1866 let parser_snapshot_before_ty = self.clone();
1867 self.eat_incorrect_doc_comment("a method argument's type");
1868 let mut ty = self.parse_ty();
1869 if ty.is_ok() && self.token == token::Colon {
1870 // This wasn't actually a type, but a pattern looking like a type,
1871 // so we are going to rollback and re-parse for recovery.
1872 ty = self.unexpected();
1876 let ident = Ident::new(keywords::Invalid.name(), self.prev_span);
1878 id: ast::DUMMY_NODE_ID,
1879 node: PatKind::Ident(
1880 BindingMode::ByValue(Mutability::Immutable), ident, None),
1886 // Recover from attempting to parse the argument as a type without pattern.
1888 mem::replace(self, parser_snapshot_before_ty);
1889 let pat = self.parse_pat(Some("argument name"))?;
1890 self.expect(&token::Colon)?;
1891 let ty = self.parse_ty()?;
1893 let mut err = self.diagnostic().struct_span_err_with_code(
1895 "patterns aren't allowed in methods without bodies",
1896 DiagnosticId::Error("E0642".into()),
1898 err.span_suggestion_short_with_applicability(
1900 "give this argument a name or use an underscore to ignore it",
1902 Applicability::MachineApplicable,
1906 // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
1908 node: PatKind::Wild,
1910 id: ast::DUMMY_NODE_ID
1917 Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID })
1920 /// Parse a single function argument
1921 crate fn parse_arg(&mut self) -> PResult<'a, Arg> {
1922 self.parse_arg_general(true, false)
1925 /// Parse an argument in a lambda header e.g., |arg, arg|
1926 fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
1927 let pat = self.parse_pat(Some("argument name"))?;
1928 let t = if self.eat(&token::Colon) {
1932 id: ast::DUMMY_NODE_ID,
1933 node: TyKind::Infer,
1934 span: self.prev_span,
1940 id: ast::DUMMY_NODE_ID
1944 fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
1945 if self.eat(&token::Semi) {
1946 Ok(Some(self.parse_expr()?))
1952 /// Matches token_lit = LIT_INTEGER | ...
1953 fn parse_lit_token(&mut self) -> PResult<'a, LitKind> {
1954 let out = match self.token {
1955 token::Interpolated(ref nt) => match nt.0 {
1956 token::NtExpr(ref v) | token::NtLiteral(ref v) => match v.node {
1957 ExprKind::Lit(ref lit) => { lit.node.clone() }
1958 _ => { return self.unexpected_last(&self.token); }
1960 _ => { return self.unexpected_last(&self.token); }
1962 token::Literal(lit, suf) => {
1963 let diag = Some((self.span, &self.sess.span_diagnostic));
1964 let (suffix_illegal, result) = parse::lit_token(lit, suf, diag);
1968 self.expect_no_suffix(sp, lit.literal_name(), suf)
1973 _ => { return self.unexpected_last(&self.token); }
1980 /// Matches lit = true | false | token_lit
1981 crate fn parse_lit(&mut self) -> PResult<'a, Lit> {
1983 let lit = if self.eat_keyword(keywords::True) {
1985 } else if self.eat_keyword(keywords::False) {
1986 LitKind::Bool(false)
1988 let lit = self.parse_lit_token()?;
1991 Ok(source_map::Spanned { node: lit, span: lo.to(self.prev_span) })
1994 /// matches '-' lit | lit (cf. ast_validation::AstValidator::check_expr_within_pat)
1995 crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
1996 maybe_whole_expr!(self);
1998 let minus_lo = self.span;
1999 let minus_present = self.eat(&token::BinOp(token::Minus));
2001 let literal = self.parse_lit()?;
2002 let hi = self.prev_span;
2003 let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
2006 let minus_hi = self.prev_span;
2007 let unary = self.mk_unary(UnOp::Neg, expr);
2008 Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
2014 fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
2016 token::Ident(ident, _) if self.token.is_path_segment_keyword() => {
2017 let span = self.span;
2019 Ok(Ident::new(ident.name, span))
2021 _ => self.parse_ident(),
2025 fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
2027 token::Ident(ident, false) if ident.name == keywords::Underscore.name() => {
2028 let span = self.span;
2030 Ok(Ident::new(ident.name, span))
2032 _ => self.parse_ident(),
2036 /// Parses qualified path.
2037 /// Assumes that the leading `<` has been parsed already.
2039 /// `qualified_path = <type [as trait_ref]>::path`
2044 /// `<T as U>::F::a<S>` (without disambiguator)
2045 /// `<T as U>::F::a::<S>` (with disambiguator)
2046 fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::Path)> {
2047 let lo = self.prev_span;
2048 let ty = self.parse_ty()?;
2050 // `path` will contain the prefix of the path up to the `>`,
2051 // if any (e.g., `U` in the `<T as U>::*` examples
2052 // above). `path_span` has the span of that path, or an empty
2053 // span in the case of something like `<T>::Bar`.
2054 let (mut path, path_span);
2055 if self.eat_keyword(keywords::As) {
2056 let path_lo = self.span;
2057 path = self.parse_path(PathStyle::Type)?;
2058 path_span = path_lo.to(self.prev_span);
2060 path = ast::Path { segments: Vec::new(), span: syntax_pos::DUMMY_SP };
2061 path_span = self.span.to(self.span);
2064 self.expect(&token::Gt)?;
2065 self.expect(&token::ModSep)?;
2067 let qself = QSelf { ty, path_span, position: path.segments.len() };
2068 self.parse_path_segments(&mut path.segments, style, true)?;
2070 Ok((qself, ast::Path { segments: path.segments, span: lo.to(self.prev_span) }))
2073 /// Parses simple paths.
2075 /// `path = [::] segment+`
2076 /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
2079 /// `a::b::C<D>` (without disambiguator)
2080 /// `a::b::C::<D>` (with disambiguator)
2081 /// `Fn(Args)` (without disambiguator)
2082 /// `Fn::(Args)` (with disambiguator)
2083 pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2084 self.parse_path_common(style, true)
2087 crate fn parse_path_common(&mut self, style: PathStyle, enable_warning: bool)
2088 -> PResult<'a, ast::Path> {
2089 maybe_whole!(self, NtPath, |path| {
2090 if style == PathStyle::Mod &&
2091 path.segments.iter().any(|segment| segment.args.is_some()) {
2092 self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
2097 let lo = self.meta_var_span.unwrap_or(self.span);
2098 let mut segments = Vec::new();
2099 let mod_sep_ctxt = self.span.ctxt();
2100 if self.eat(&token::ModSep) {
2101 segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
2103 self.parse_path_segments(&mut segments, style, enable_warning)?;
2105 Ok(ast::Path { segments, span: lo.to(self.prev_span) })
2108 /// Like `parse_path`, but also supports parsing `Word` meta items into paths for back-compat.
2109 /// This is used when parsing derive macro paths in `#[derive]` attributes.
2110 pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2111 let meta_ident = match self.token {
2112 token::Interpolated(ref nt) => match nt.0 {
2113 token::NtMeta(ref meta) => match meta.node {
2114 ast::MetaItemKind::Word => Some(meta.ident.clone()),
2121 if let Some(path) = meta_ident {
2125 self.parse_path(style)
2128 fn parse_path_segments(&mut self,
2129 segments: &mut Vec<PathSegment>,
2131 enable_warning: bool)
2132 -> PResult<'a, ()> {
2134 segments.push(self.parse_path_segment(style, enable_warning)?);
2136 if self.is_import_coupler() || !self.eat(&token::ModSep) {
2142 fn parse_path_segment(&mut self, style: PathStyle, enable_warning: bool)
2143 -> PResult<'a, PathSegment> {
2144 let ident = self.parse_path_segment_ident()?;
2146 let is_args_start = |token: &token::Token| match *token {
2147 token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren) => true,
2150 let check_args_start = |this: &mut Self| {
2151 this.expected_tokens.extend_from_slice(
2152 &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
2154 is_args_start(&this.token)
2157 Ok(if style == PathStyle::Type && check_args_start(self) ||
2158 style != PathStyle::Mod && self.check(&token::ModSep)
2159 && self.look_ahead(1, |t| is_args_start(t)) {
2160 // Generic arguments are found - `<`, `(`, `::<` or `::(`.
2162 if self.eat(&token::ModSep) && style == PathStyle::Type && enable_warning {
2163 self.diagnostic().struct_span_warn(self.prev_span, "unnecessary path disambiguator")
2164 .span_label(self.prev_span, "try removing `::`").emit();
2167 let args = if self.eat_lt() {
2169 let (args, bindings) = self.parse_generic_args()?;
2171 let span = lo.to(self.prev_span);
2172 AngleBracketedArgs { args, bindings, span }.into()
2176 let inputs = self.parse_seq_to_before_tokens(
2177 &[&token::CloseDelim(token::Paren)],
2178 SeqSep::trailing_allowed(token::Comma),
2179 TokenExpectType::Expect,
2182 let span = lo.to(self.prev_span);
2183 let output = if self.eat(&token::RArrow) {
2184 Some(self.parse_ty_common(false, false)?)
2188 ParenthesisedArgs { inputs, output, span }.into()
2191 PathSegment { ident, args, id: ast::DUMMY_NODE_ID }
2193 // Generic arguments are not found.
2194 PathSegment::from_ident(ident)
2198 crate fn check_lifetime(&mut self) -> bool {
2199 self.expected_tokens.push(TokenType::Lifetime);
2200 self.token.is_lifetime()
2203 /// Parse single lifetime 'a or panic.
2204 crate fn expect_lifetime(&mut self) -> Lifetime {
2205 if let Some(ident) = self.token.lifetime() {
2206 let span = self.span;
2208 Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
2210 self.span_bug(self.span, "not a lifetime")
2214 fn eat_label(&mut self) -> Option<Label> {
2215 if let Some(ident) = self.token.lifetime() {
2216 let span = self.span;
2218 Some(Label { ident: Ident::new(ident.name, span) })
2224 /// Parse mutability (`mut` or nothing).
2225 fn parse_mutability(&mut self) -> Mutability {
2226 if self.eat_keyword(keywords::Mut) {
2229 Mutability::Immutable
2233 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
2234 if let token::Literal(token::Integer(name), None) = self.token {
2236 Ok(Ident::new(name, self.prev_span))
2238 self.parse_ident_common(false)
2242 /// Parse ident (COLON expr)?
2243 fn parse_field(&mut self) -> PResult<'a, Field> {
2244 let attrs = self.parse_outer_attributes()?;
2247 // Check if a colon exists one ahead. This means we're parsing a fieldname.
2248 let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
2249 let fieldname = self.parse_field_name()?;
2251 (fieldname, self.parse_expr()?, false)
2253 let fieldname = self.parse_ident_common(false)?;
2255 // Mimic `x: x` for the `x` field shorthand.
2256 let path = ast::Path::from_ident(fieldname);
2257 let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
2258 (fieldname, expr, true)
2262 span: lo.to(expr.span),
2265 attrs: attrs.into(),
2269 fn mk_expr(&mut self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
2270 P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID })
2273 fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
2274 ExprKind::Unary(unop, expr)
2277 fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2278 ExprKind::Binary(binop, lhs, rhs)
2281 fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
2282 ExprKind::Call(f, args)
2285 fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
2286 ExprKind::Index(expr, idx)
2289 fn mk_range(&mut self,
2290 start: Option<P<Expr>>,
2291 end: Option<P<Expr>>,
2292 limits: RangeLimits)
2293 -> PResult<'a, ast::ExprKind> {
2294 if end.is_none() && limits == RangeLimits::Closed {
2295 Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd))
2297 Ok(ExprKind::Range(start, end, limits))
2301 fn mk_assign_op(&mut self, binop: ast::BinOp,
2302 lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2303 ExprKind::AssignOp(binop, lhs, rhs)
2306 pub fn mk_mac_expr(&mut self, span: Span, m: Mac_, attrs: ThinVec<Attribute>) -> P<Expr> {
2308 id: ast::DUMMY_NODE_ID,
2309 node: ExprKind::Mac(source_map::Spanned {node: m, span: span}),
2315 fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, ThinTokenStream)> {
2316 let delim = match self.token {
2317 token::OpenDelim(delim) => delim,
2319 let msg = "expected open delimiter";
2320 let mut err = self.fatal(msg);
2321 err.span_label(self.span, msg);
2325 let tts = match self.parse_token_tree() {
2326 TokenTree::Delimited(_, _, tts) => tts,
2327 _ => unreachable!(),
2329 let delim = match delim {
2330 token::Paren => MacDelimiter::Parenthesis,
2331 token::Bracket => MacDelimiter::Bracket,
2332 token::Brace => MacDelimiter::Brace,
2333 token::NoDelim => self.bug("unexpected no delimiter"),
2335 Ok((delim, tts.stream().into()))
2338 /// At the bottom (top?) of the precedence hierarchy,
2339 /// parse things like parenthesized exprs,
2340 /// macros, return, etc.
2342 /// N.B., this does not parse outer attributes,
2343 /// and is private because it only works
2344 /// correctly if called from parse_dot_or_call_expr().
2345 fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
2346 maybe_whole_expr!(self);
2348 // Outer attributes are already parsed and will be
2349 // added to the return value after the fact.
2351 // Therefore, prevent sub-parser from parsing
2352 // attributes by giving them a empty "already parsed" list.
2353 let mut attrs = ThinVec::new();
2356 let mut hi = self.span;
2360 // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2362 token::OpenDelim(token::Paren) => {
2365 attrs.extend(self.parse_inner_attributes()?);
2367 // (e) is parenthesized e
2368 // (e,) is a tuple with only one field, e
2369 let mut es = vec![];
2370 let mut trailing_comma = false;
2371 while self.token != token::CloseDelim(token::Paren) {
2372 es.push(self.parse_expr()?);
2373 self.expect_one_of(&[], &[token::Comma, token::CloseDelim(token::Paren)])?;
2374 if self.eat(&token::Comma) {
2375 trailing_comma = true;
2377 trailing_comma = false;
2383 hi = self.prev_span;
2384 ex = if es.len() == 1 && !trailing_comma {
2385 ExprKind::Paren(es.into_iter().nth(0).unwrap())
2390 token::OpenDelim(token::Brace) => {
2391 return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
2393 token::BinOp(token::Or) | token::OrOr => {
2394 return self.parse_lambda_expr(attrs);
2396 token::OpenDelim(token::Bracket) => {
2399 attrs.extend(self.parse_inner_attributes()?);
2401 if self.eat(&token::CloseDelim(token::Bracket)) {
2403 ex = ExprKind::Array(Vec::new());
2406 let first_expr = self.parse_expr()?;
2407 if self.eat(&token::Semi) {
2408 // Repeating array syntax: [ 0; 512 ]
2409 let count = AnonConst {
2410 id: ast::DUMMY_NODE_ID,
2411 value: self.parse_expr()?,
2413 self.expect(&token::CloseDelim(token::Bracket))?;
2414 ex = ExprKind::Repeat(first_expr, count);
2415 } else if self.eat(&token::Comma) {
2416 // Vector with two or more elements.
2417 let remaining_exprs = self.parse_seq_to_end(
2418 &token::CloseDelim(token::Bracket),
2419 SeqSep::trailing_allowed(token::Comma),
2420 |p| Ok(p.parse_expr()?)
2422 let mut exprs = vec![first_expr];
2423 exprs.extend(remaining_exprs);
2424 ex = ExprKind::Array(exprs);
2426 // Vector with one element.
2427 self.expect(&token::CloseDelim(token::Bracket))?;
2428 ex = ExprKind::Array(vec![first_expr]);
2431 hi = self.prev_span;
2435 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
2437 return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
2439 if self.span.rust_2018() && self.check_keyword(keywords::Async)
2441 if self.is_async_block() { // check for `async {` and `async move {`
2442 return self.parse_async_block(attrs);
2444 return self.parse_lambda_expr(attrs);
2447 if self.check_keyword(keywords::Move) || self.check_keyword(keywords::Static) {
2448 return self.parse_lambda_expr(attrs);
2450 if self.eat_keyword(keywords::If) {
2451 return self.parse_if_expr(attrs);
2453 if self.eat_keyword(keywords::For) {
2454 let lo = self.prev_span;
2455 return self.parse_for_expr(None, lo, attrs);
2457 if self.eat_keyword(keywords::While) {
2458 let lo = self.prev_span;
2459 return self.parse_while_expr(None, lo, attrs);
2461 if let Some(label) = self.eat_label() {
2462 let lo = label.ident.span;
2463 self.expect(&token::Colon)?;
2464 if self.eat_keyword(keywords::While) {
2465 return self.parse_while_expr(Some(label), lo, attrs)
2467 if self.eat_keyword(keywords::For) {
2468 return self.parse_for_expr(Some(label), lo, attrs)
2470 if self.eat_keyword(keywords::Loop) {
2471 return self.parse_loop_expr(Some(label), lo, attrs)
2473 if self.token == token::OpenDelim(token::Brace) {
2474 return self.parse_block_expr(Some(label),
2476 BlockCheckMode::Default,
2479 let msg = "expected `while`, `for`, `loop` or `{` after a label";
2480 let mut err = self.fatal(msg);
2481 err.span_label(self.span, msg);
2484 if self.eat_keyword(keywords::Loop) {
2485 let lo = self.prev_span;
2486 return self.parse_loop_expr(None, lo, attrs);
2488 if self.eat_keyword(keywords::Continue) {
2489 let label = self.eat_label();
2490 let ex = ExprKind::Continue(label);
2491 let hi = self.prev_span;
2492 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2494 if self.eat_keyword(keywords::Match) {
2495 let match_sp = self.prev_span;
2496 return self.parse_match_expr(attrs).map_err(|mut err| {
2497 err.span_label(match_sp, "while parsing this match expression");
2501 if self.eat_keyword(keywords::Unsafe) {
2502 return self.parse_block_expr(
2505 BlockCheckMode::Unsafe(ast::UserProvided),
2508 if self.is_do_catch_block() {
2509 let mut db = self.fatal("found removed `do catch` syntax");
2510 db.help("Following RFC #2388, the new non-placeholder syntax is `try`");
2513 if self.is_try_block() {
2515 assert!(self.eat_keyword(keywords::Try));
2516 return self.parse_try_block(lo, attrs);
2518 if self.eat_keyword(keywords::Return) {
2519 if self.token.can_begin_expr() {
2520 let e = self.parse_expr()?;
2522 ex = ExprKind::Ret(Some(e));
2524 ex = ExprKind::Ret(None);
2526 } else if self.eat_keyword(keywords::Break) {
2527 let label = self.eat_label();
2528 let e = if self.token.can_begin_expr()
2529 && !(self.token == token::OpenDelim(token::Brace)
2530 && self.restrictions.contains(
2531 Restrictions::NO_STRUCT_LITERAL)) {
2532 Some(self.parse_expr()?)
2536 ex = ExprKind::Break(label, e);
2537 hi = self.prev_span;
2538 } else if self.eat_keyword(keywords::Yield) {
2539 if self.token.can_begin_expr() {
2540 let e = self.parse_expr()?;
2542 ex = ExprKind::Yield(Some(e));
2544 ex = ExprKind::Yield(None);
2546 } else if self.token.is_keyword(keywords::Let) {
2547 // Catch this syntax error here, instead of in `parse_ident`, so
2548 // that we can explicitly mention that let is not to be used as an expression
2549 let mut db = self.fatal("expected expression, found statement (`let`)");
2550 db.span_label(self.span, "expected expression");
2551 db.note("variable declaration using `let` is a statement");
2553 } else if self.token.is_path_start() {
2554 let pth = self.parse_path(PathStyle::Expr)?;
2556 // `!`, as an operator, is prefix, so we know this isn't that
2557 if self.eat(&token::Not) {
2558 // MACRO INVOCATION expression
2559 let (delim, tts) = self.expect_delimited_token_tree()?;
2560 let hi = self.prev_span;
2561 let node = Mac_ { path: pth, tts, delim };
2562 return Ok(self.mk_mac_expr(lo.to(hi), node, attrs))
2564 if self.check(&token::OpenDelim(token::Brace)) {
2565 // This is a struct literal, unless we're prohibited
2566 // from parsing struct literals here.
2567 let prohibited = self.restrictions.contains(
2568 Restrictions::NO_STRUCT_LITERAL
2571 return self.parse_struct_expr(lo, pth, attrs);
2576 ex = ExprKind::Path(None, pth);
2578 match self.parse_literal_maybe_minus() {
2581 ex = expr.node.clone();
2584 self.cancel(&mut err);
2585 let msg = format!("expected expression, found {}",
2586 self.this_token_descr());
2587 let mut err = self.fatal(&msg);
2588 err.span_label(self.span, "expected expression");
2596 let expr = Expr { node: ex, span: lo.to(hi), id: ast::DUMMY_NODE_ID, attrs };
2597 let expr = self.maybe_recover_from_bad_qpath(expr, true)?;
2602 fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Attribute>)
2603 -> PResult<'a, P<Expr>> {
2604 let struct_sp = lo.to(self.prev_span);
2606 let mut fields = Vec::new();
2607 let mut base = None;
2609 attrs.extend(self.parse_inner_attributes()?);
2611 while self.token != token::CloseDelim(token::Brace) {
2612 if self.eat(&token::DotDot) {
2613 let exp_span = self.prev_span;
2614 match self.parse_expr() {
2620 self.recover_stmt();
2623 if self.token == token::Comma {
2624 let mut err = self.sess.span_diagnostic.mut_span_err(
2625 exp_span.to(self.prev_span),
2626 "cannot use a comma after the base struct",
2628 err.span_suggestion_short_with_applicability(
2630 "remove this comma",
2632 Applicability::MachineApplicable
2634 err.note("the base struct must always be the last field");
2636 self.recover_stmt();
2641 match self.parse_field() {
2642 Ok(f) => fields.push(f),
2644 e.span_label(struct_sp, "while parsing this struct");
2647 // If the next token is a comma, then try to parse
2648 // what comes next as additional fields, rather than
2649 // bailing out until next `}`.
2650 if self.token != token::Comma {
2651 self.recover_stmt();
2657 match self.expect_one_of(&[token::Comma],
2658 &[token::CloseDelim(token::Brace)]) {
2662 self.recover_stmt();
2668 let span = lo.to(self.span);
2669 self.expect(&token::CloseDelim(token::Brace))?;
2670 return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
2673 fn parse_or_use_outer_attributes(&mut self,
2674 already_parsed_attrs: Option<ThinVec<Attribute>>)
2675 -> PResult<'a, ThinVec<Attribute>> {
2676 if let Some(attrs) = already_parsed_attrs {
2679 self.parse_outer_attributes().map(|a| a.into())
2683 /// Parse a block or unsafe block
2684 fn parse_block_expr(&mut self, opt_label: Option<Label>,
2685 lo: Span, blk_mode: BlockCheckMode,
2686 outer_attrs: ThinVec<Attribute>)
2687 -> PResult<'a, P<Expr>> {
2688 self.expect(&token::OpenDelim(token::Brace))?;
2690 let mut attrs = outer_attrs;
2691 attrs.extend(self.parse_inner_attributes()?);
2693 let blk = self.parse_block_tail(lo, blk_mode)?;
2694 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs));
2697 /// parse a.b or a(13) or a[4] or just a
2698 fn parse_dot_or_call_expr(&mut self,
2699 already_parsed_attrs: Option<ThinVec<Attribute>>)
2700 -> PResult<'a, P<Expr>> {
2701 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2703 let b = self.parse_bottom_expr();
2704 let (span, b) = self.interpolated_or_expr_span(b)?;
2705 self.parse_dot_or_call_expr_with(b, span, attrs)
2708 fn parse_dot_or_call_expr_with(&mut self,
2711 mut attrs: ThinVec<Attribute>)
2712 -> PResult<'a, P<Expr>> {
2713 // Stitch the list of outer attributes onto the return value.
2714 // A little bit ugly, but the best way given the current code
2716 self.parse_dot_or_call_expr_with_(e0, lo)
2718 expr.map(|mut expr| {
2719 attrs.extend::<Vec<_>>(expr.attrs.into());
2722 ExprKind::If(..) | ExprKind::IfLet(..) => {
2723 if !expr.attrs.is_empty() {
2724 // Just point to the first attribute in there...
2725 let span = expr.attrs[0].span;
2728 "attributes are not yet allowed on `if` \
2739 // Assuming we have just parsed `.`, continue parsing into an expression.
2740 fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2741 let segment = self.parse_path_segment(PathStyle::Expr, true)?;
2742 Ok(match self.token {
2743 token::OpenDelim(token::Paren) => {
2744 // Method call `expr.f()`
2745 let mut args = self.parse_unspanned_seq(
2746 &token::OpenDelim(token::Paren),
2747 &token::CloseDelim(token::Paren),
2748 SeqSep::trailing_allowed(token::Comma),
2749 |p| Ok(p.parse_expr()?)
2751 args.insert(0, self_arg);
2753 let span = lo.to(self.prev_span);
2754 self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
2757 // Field access `expr.f`
2758 if let Some(args) = segment.args {
2759 self.span_err(args.span(),
2760 "field expressions may not have generic arguments");
2763 let span = lo.to(self.prev_span);
2764 self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
2769 fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2774 while self.eat(&token::Question) {
2775 let hi = self.prev_span;
2776 e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
2780 if self.eat(&token::Dot) {
2782 token::Ident(..) => {
2783 e = self.parse_dot_suffix(e, lo)?;
2785 token::Literal(token::Integer(name), _) => {
2786 let span = self.span;
2788 let field = ExprKind::Field(e, Ident::new(name, span));
2789 e = self.mk_expr(lo.to(span), field, ThinVec::new());
2791 token::Literal(token::Float(n), _suf) => {
2793 let fstr = n.as_str();
2794 let mut err = self.diagnostic()
2795 .struct_span_err(self.prev_span, &format!("unexpected token: `{}`", n));
2796 err.span_label(self.prev_span, "unexpected token");
2797 if fstr.chars().all(|x| "0123456789.".contains(x)) {
2798 let float = match fstr.parse::<f64>().ok() {
2802 let sugg = pprust::to_string(|s| {
2803 use print::pprust::PrintState;
2807 s.print_usize(float.trunc() as usize)?;
2810 s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
2812 err.span_suggestion_with_applicability(
2813 lo.to(self.prev_span),
2814 "try parenthesizing the first index",
2816 Applicability::MachineApplicable
2823 // FIXME Could factor this out into non_fatal_unexpected or something.
2824 let actual = self.this_token_to_string();
2825 self.span_err(self.span, &format!("unexpected token: `{}`", actual));
2830 if self.expr_is_complete(&e) { break; }
2833 token::OpenDelim(token::Paren) => {
2834 let es = self.parse_unspanned_seq(
2835 &token::OpenDelim(token::Paren),
2836 &token::CloseDelim(token::Paren),
2837 SeqSep::trailing_allowed(token::Comma),
2838 |p| Ok(p.parse_expr()?)
2840 hi = self.prev_span;
2842 let nd = self.mk_call(e, es);
2843 e = self.mk_expr(lo.to(hi), nd, ThinVec::new());
2847 // Could be either an index expression or a slicing expression.
2848 token::OpenDelim(token::Bracket) => {
2850 let ix = self.parse_expr()?;
2852 self.expect(&token::CloseDelim(token::Bracket))?;
2853 let index = self.mk_index(e, ix);
2854 e = self.mk_expr(lo.to(hi), index, ThinVec::new())
2862 crate fn process_potential_macro_variable(&mut self) {
2863 let (token, span) = match self.token {
2864 token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
2865 self.look_ahead(1, |t| t.is_ident()) => {
2867 let name = match self.token {
2868 token::Ident(ident, _) => ident,
2871 let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
2872 err.span_label(self.span, "unknown macro variable");
2877 token::Interpolated(ref nt) => {
2878 self.meta_var_span = Some(self.span);
2879 // Interpolated identifier and lifetime tokens are replaced with usual identifier
2880 // and lifetime tokens, so the former are never encountered during normal parsing.
2882 token::NtIdent(ident, is_raw) => (token::Ident(ident, is_raw), ident.span),
2883 token::NtLifetime(ident) => (token::Lifetime(ident), ident.span),
2893 /// parse a single token tree from the input.
2894 crate fn parse_token_tree(&mut self) -> TokenTree {
2896 token::OpenDelim(..) => {
2897 let frame = mem::replace(&mut self.token_cursor.frame,
2898 self.token_cursor.stack.pop().unwrap());
2899 self.span = frame.span.entire();
2901 TokenTree::Delimited(
2904 frame.tree_cursor.original_stream().into(),
2907 token::CloseDelim(_) | token::Eof => unreachable!(),
2909 let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span);
2911 TokenTree::Token(span, token)
2916 // parse a stream of tokens into a list of TokenTree's,
2918 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
2919 let mut tts = Vec::new();
2920 while self.token != token::Eof {
2921 tts.push(self.parse_token_tree());
2926 pub fn parse_tokens(&mut self) -> TokenStream {
2927 let mut result = Vec::new();
2930 token::Eof | token::CloseDelim(..) => break,
2931 _ => result.push(self.parse_token_tree().into()),
2934 TokenStream::new(result)
2937 /// Parse a prefix-unary-operator expr
2938 fn parse_prefix_expr(&mut self,
2939 already_parsed_attrs: Option<ThinVec<Attribute>>)
2940 -> PResult<'a, P<Expr>> {
2941 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2943 // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2944 let (hi, ex) = match self.token {
2947 let e = self.parse_prefix_expr(None);
2948 let (span, e) = self.interpolated_or_expr_span(e)?;
2949 (lo.to(span), self.mk_unary(UnOp::Not, e))
2951 // Suggest `!` for bitwise negation when encountering a `~`
2954 let e = self.parse_prefix_expr(None);
2955 let (span, e) = self.interpolated_or_expr_span(e)?;
2956 let span_of_tilde = lo;
2957 let mut err = self.diagnostic()
2958 .struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator");
2959 err.span_suggestion_short_with_applicability(
2961 "use `!` to perform bitwise negation",
2963 Applicability::MachineApplicable
2966 (lo.to(span), self.mk_unary(UnOp::Not, e))
2968 token::BinOp(token::Minus) => {
2970 let e = self.parse_prefix_expr(None);
2971 let (span, e) = self.interpolated_or_expr_span(e)?;
2972 (lo.to(span), self.mk_unary(UnOp::Neg, e))
2974 token::BinOp(token::Star) => {
2976 let e = self.parse_prefix_expr(None);
2977 let (span, e) = self.interpolated_or_expr_span(e)?;
2978 (lo.to(span), self.mk_unary(UnOp::Deref, e))
2980 token::BinOp(token::And) | token::AndAnd => {
2982 let m = self.parse_mutability();
2983 let e = self.parse_prefix_expr(None);
2984 let (span, e) = self.interpolated_or_expr_span(e)?;
2985 (lo.to(span), ExprKind::AddrOf(m, e))
2987 token::Ident(..) if self.token.is_keyword(keywords::In) => {
2989 let place = self.parse_expr_res(
2990 Restrictions::NO_STRUCT_LITERAL,
2993 let blk = self.parse_block()?;
2994 let span = blk.span;
2995 let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new());
2996 (lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr))
2998 token::Ident(..) if self.token.is_keyword(keywords::Box) => {
3000 let e = self.parse_prefix_expr(None);
3001 let (span, e) = self.interpolated_or_expr_span(e)?;
3002 (lo.to(span), ExprKind::Box(e))
3004 token::Ident(..) if self.token.is_ident_named("not") => {
3005 // `not` is just an ordinary identifier in Rust-the-language,
3006 // but as `rustc`-the-compiler, we can issue clever diagnostics
3007 // for confused users who really want to say `!`
3008 let token_cannot_continue_expr = |t: &token::Token| match *t {
3009 // These tokens can start an expression after `!`, but
3010 // can't continue an expression after an ident
3011 token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw),
3012 token::Literal(..) | token::Pound => true,
3013 token::Interpolated(ref nt) => match nt.0 {
3014 token::NtIdent(..) | token::NtExpr(..) |
3015 token::NtBlock(..) | token::NtPath(..) => true,
3020 let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
3021 if cannot_continue_expr {
3023 // Emit the error ...
3024 let mut err = self.diagnostic()
3025 .struct_span_err(self.span,
3026 &format!("unexpected {} after identifier",
3027 self.this_token_descr()));
3028 // span the `not` plus trailing whitespace to avoid
3029 // trailing whitespace after the `!` in our suggestion
3030 let to_replace = self.sess.source_map()
3031 .span_until_non_whitespace(lo.to(self.span));
3032 err.span_suggestion_short_with_applicability(
3034 "use `!` to perform logical negation",
3036 Applicability::MachineApplicable
3039 // —and recover! (just as if we were in the block
3040 // for the `token::Not` arm)
3041 let e = self.parse_prefix_expr(None);
3042 let (span, e) = self.interpolated_or_expr_span(e)?;
3043 (lo.to(span), self.mk_unary(UnOp::Not, e))
3045 return self.parse_dot_or_call_expr(Some(attrs));
3048 _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
3050 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
3053 /// Parse an associative expression
3055 /// This parses an expression accounting for associativity and precedence of the operators in
3058 fn parse_assoc_expr(&mut self,
3059 already_parsed_attrs: Option<ThinVec<Attribute>>)
3060 -> PResult<'a, P<Expr>> {
3061 self.parse_assoc_expr_with(0, already_parsed_attrs.into())
3064 /// Parse an associative expression with operators of at least `min_prec` precedence
3065 fn parse_assoc_expr_with(&mut self,
3068 -> PResult<'a, P<Expr>> {
3069 let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
3072 let attrs = match lhs {
3073 LhsExpr::AttributesParsed(attrs) => Some(attrs),
3076 if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token) {
3077 return self.parse_prefix_range_expr(attrs);
3079 self.parse_prefix_expr(attrs)?
3083 if self.expr_is_complete(&lhs) {
3084 // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
3087 self.expected_tokens.push(TokenType::Operator);
3088 while let Some(op) = AssocOp::from_token(&self.token) {
3090 // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
3091 // it refers to. Interpolated identifiers are unwrapped early and never show up here
3092 // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
3093 // it as "interpolated", it doesn't change the answer for non-interpolated idents.
3094 let lhs_span = match (self.prev_token_kind, &lhs.node) {
3095 (PrevTokenKind::Interpolated, _) => self.prev_span,
3096 (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
3097 if path.segments.len() == 1 => self.prev_span,
3101 let cur_op_span = self.span;
3102 let restrictions = if op.is_assign_like() {
3103 self.restrictions & Restrictions::NO_STRUCT_LITERAL
3107 if op.precedence() < min_prec {
3110 // Check for deprecated `...` syntax
3111 if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
3112 self.err_dotdotdot_syntax(self.span);
3116 if op.is_comparison() {
3117 self.check_no_chained_comparison(&lhs, &op);
3120 if op == AssocOp::As {
3121 lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
3123 } else if op == AssocOp::Colon {
3124 lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) {
3127 err.span_label(self.span,
3128 "expecting a type here because of type ascription");
3129 let cm = self.sess.source_map();
3130 let cur_pos = cm.lookup_char_pos(self.span.lo());
3131 let op_pos = cm.lookup_char_pos(cur_op_span.hi());
3132 if cur_pos.line != op_pos.line {
3133 err.span_suggestion_with_applicability(
3135 "try using a semicolon",
3137 Applicability::MaybeIncorrect // speculative
3144 } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
3145 // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
3146 // generalise it to the Fixity::None code.
3148 // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
3149 // two variants are handled with `parse_prefix_range_expr` call above.
3150 let rhs = if self.is_at_start_of_range_notation_rhs() {
3151 Some(self.parse_assoc_expr_with(op.precedence() + 1,
3152 LhsExpr::NotYetParsed)?)
3156 let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
3161 let limits = if op == AssocOp::DotDot {
3162 RangeLimits::HalfOpen
3167 let r = self.mk_range(Some(lhs), rhs, limits)?;
3168 lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
3172 let rhs = match op.fixity() {
3173 Fixity::Right => self.with_res(
3174 restrictions - Restrictions::STMT_EXPR,
3176 this.parse_assoc_expr_with(op.precedence(),
3177 LhsExpr::NotYetParsed)
3179 Fixity::Left => self.with_res(
3180 restrictions - Restrictions::STMT_EXPR,
3182 this.parse_assoc_expr_with(op.precedence() + 1,
3183 LhsExpr::NotYetParsed)
3185 // We currently have no non-associative operators that are not handled above by
3186 // the special cases. The code is here only for future convenience.
3187 Fixity::None => self.with_res(
3188 restrictions - Restrictions::STMT_EXPR,
3190 this.parse_assoc_expr_with(op.precedence() + 1,
3191 LhsExpr::NotYetParsed)
3195 let span = lhs_span.to(rhs.span);
3197 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
3198 AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
3199 AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
3200 AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
3201 AssocOp::Greater | AssocOp::GreaterEqual => {
3202 let ast_op = op.to_ast_binop().unwrap();
3203 let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
3204 self.mk_expr(span, binary, ThinVec::new())
3207 self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
3208 AssocOp::ObsoleteInPlace =>
3209 self.mk_expr(span, ExprKind::ObsoleteInPlace(lhs, rhs), ThinVec::new()),
3210 AssocOp::AssignOp(k) => {
3212 token::Plus => BinOpKind::Add,
3213 token::Minus => BinOpKind::Sub,
3214 token::Star => BinOpKind::Mul,
3215 token::Slash => BinOpKind::Div,
3216 token::Percent => BinOpKind::Rem,
3217 token::Caret => BinOpKind::BitXor,
3218 token::And => BinOpKind::BitAnd,
3219 token::Or => BinOpKind::BitOr,
3220 token::Shl => BinOpKind::Shl,
3221 token::Shr => BinOpKind::Shr,
3223 let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
3224 self.mk_expr(span, aopexpr, ThinVec::new())
3226 AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
3227 self.bug("AssocOp should have been handled by special case")
3231 if op.fixity() == Fixity::None { break }
3236 fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
3237 expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
3238 -> PResult<'a, P<Expr>> {
3239 let mk_expr = |this: &mut Self, rhs: P<Ty>| {
3240 this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
3243 // Save the state of the parser before parsing type normally, in case there is a
3244 // LessThan comparison after this cast.
3245 let parser_snapshot_before_type = self.clone();
3246 match self.parse_ty_no_plus() {
3248 Ok(mk_expr(self, rhs))
3250 Err(mut type_err) => {
3251 // Rewind to before attempting to parse the type with generics, to recover
3252 // from situations like `x as usize < y` in which we first tried to parse
3253 // `usize < y` as a type with generic arguments.
3254 let parser_snapshot_after_type = self.clone();
3255 mem::replace(self, parser_snapshot_before_type);
3257 match self.parse_path(PathStyle::Expr) {
3259 let (op_noun, op_verb) = match self.token {
3260 token::Lt => ("comparison", "comparing"),
3261 token::BinOp(token::Shl) => ("shift", "shifting"),
3263 // We can end up here even without `<` being the next token, for
3264 // example because `parse_ty_no_plus` returns `Err` on keywords,
3265 // but `parse_path` returns `Ok` on them due to error recovery.
3266 // Return original error and parser state.
3267 mem::replace(self, parser_snapshot_after_type);
3268 return Err(type_err);
3272 // Successfully parsed the type path leaving a `<` yet to parse.
3275 // Report non-fatal diagnostics, keep `x as usize` as an expression
3276 // in AST and continue parsing.
3277 let msg = format!("`<` is interpreted as a start of generic \
3278 arguments for `{}`, not a {}", path, op_noun);
3279 let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
3280 err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span),
3281 "interpreted as generic arguments");
3282 err.span_label(self.span, format!("not interpreted as {}", op_noun));
3284 let expr = mk_expr(self, P(Ty {
3286 node: TyKind::Path(None, path),
3287 id: ast::DUMMY_NODE_ID
3290 let expr_str = self.sess.source_map().span_to_snippet(expr.span)
3291 .unwrap_or_else(|_| pprust::expr_to_string(&expr));
3292 err.span_suggestion_with_applicability(
3294 &format!("try {} the cast value", op_verb),
3295 format!("({})", expr_str),
3296 Applicability::MachineApplicable
3302 Err(mut path_err) => {
3303 // Couldn't parse as a path, return original error and parser state.
3305 mem::replace(self, parser_snapshot_after_type);
3313 /// Produce an error if comparison operators are chained (RFC #558).
3314 /// We only need to check lhs, not rhs, because all comparison ops
3315 /// have same precedence and are left-associative
3316 fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
3317 debug_assert!(outer_op.is_comparison(),
3318 "check_no_chained_comparison: {:?} is not comparison",
3321 ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
3322 // respan to include both operators
3323 let op_span = op.span.to(self.span);
3324 let mut err = self.diagnostic().struct_span_err(op_span,
3325 "chained comparison operators require parentheses");
3326 if op.node == BinOpKind::Lt &&
3327 *outer_op == AssocOp::Less || // Include `<` to provide this recommendation
3328 *outer_op == AssocOp::Greater // even in a case like the following:
3329 { // Foo<Bar<Baz<Qux, ()>>>
3331 "use `::<...>` instead of `<...>` if you meant to specify type arguments");
3332 err.help("or use `(...)` if you meant to specify fn arguments");
3340 /// Parse prefix-forms of range notation: `..expr`, `..`, `..=expr`
3341 fn parse_prefix_range_expr(&mut self,
3342 already_parsed_attrs: Option<ThinVec<Attribute>>)
3343 -> PResult<'a, P<Expr>> {
3344 // Check for deprecated `...` syntax
3345 if self.token == token::DotDotDot {
3346 self.err_dotdotdot_syntax(self.span);
3349 debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token),
3350 "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
3352 let tok = self.token.clone();
3353 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
3355 let mut hi = self.span;
3357 let opt_end = if self.is_at_start_of_range_notation_rhs() {
3358 // RHS must be parsed with more associativity than the dots.
3359 let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
3360 Some(self.parse_assoc_expr_with(next_prec,
3361 LhsExpr::NotYetParsed)
3369 let limits = if tok == token::DotDot {
3370 RangeLimits::HalfOpen
3375 let r = self.mk_range(None, opt_end, limits)?;
3376 Ok(self.mk_expr(lo.to(hi), r, attrs))
3379 fn is_at_start_of_range_notation_rhs(&self) -> bool {
3380 if self.token.can_begin_expr() {
3381 // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
3382 if self.token == token::OpenDelim(token::Brace) {
3383 return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
3391 /// Parse an 'if' or 'if let' expression ('if' token already eaten)
3392 fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3393 if self.check_keyword(keywords::Let) {
3394 return self.parse_if_let_expr(attrs);
3396 let lo = self.prev_span;
3397 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3399 // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
3400 // verify that the last statement is either an implicit return (no `;`) or an explicit
3401 // return. This won't catch blocks with an explicit `return`, but that would be caught by
3402 // the dead code lint.
3403 if self.eat_keyword(keywords::Else) || !cond.returns() {
3404 let sp = self.sess.source_map().next_point(lo);
3405 let mut err = self.diagnostic()
3406 .struct_span_err(sp, "missing condition for `if` statemement");
3407 err.span_label(sp, "expected if condition here");
3410 let not_block = self.token != token::OpenDelim(token::Brace);
3411 let thn = self.parse_block().map_err(|mut err| {
3413 err.span_label(lo, "this `if` statement has a condition, but no block");
3417 let mut els: Option<P<Expr>> = None;
3418 let mut hi = thn.span;
3419 if self.eat_keyword(keywords::Else) {
3420 let elexpr = self.parse_else_expr()?;
3424 Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
3427 /// Parse an 'if let' expression ('if' token already eaten)
3428 fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
3429 -> PResult<'a, P<Expr>> {
3430 let lo = self.prev_span;
3431 self.expect_keyword(keywords::Let)?;
3432 let pats = self.parse_pats()?;
3433 self.expect(&token::Eq)?;
3434 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3435 let thn = self.parse_block()?;
3436 let (hi, els) = if self.eat_keyword(keywords::Else) {
3437 let expr = self.parse_else_expr()?;
3438 (expr.span, Some(expr))
3442 Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
3445 // `move |args| expr`
3446 fn parse_lambda_expr(&mut self,
3447 attrs: ThinVec<Attribute>)
3448 -> PResult<'a, P<Expr>>
3451 let movability = if self.eat_keyword(keywords::Static) {
3456 let asyncness = if self.span.rust_2018() {
3457 self.parse_asyncness()
3461 let capture_clause = if self.eat_keyword(keywords::Move) {
3466 let decl = self.parse_fn_block_decl()?;
3467 let decl_hi = self.prev_span;
3468 let body = match decl.output {
3469 FunctionRetTy::Default(_) => {
3470 let restrictions = self.restrictions - Restrictions::STMT_EXPR;
3471 self.parse_expr_res(restrictions, None)?
3474 // If an explicit return type is given, require a
3475 // block to appear (RFC 968).
3476 let body_lo = self.span;
3477 self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
3483 ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
3487 // `else` token already eaten
3488 fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
3489 if self.eat_keyword(keywords::If) {
3490 return self.parse_if_expr(ThinVec::new());
3492 let blk = self.parse_block()?;
3493 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
3497 /// Parse a 'for' .. 'in' expression ('for' token already eaten)
3498 fn parse_for_expr(&mut self, opt_label: Option<Label>,
3500 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3501 // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
3503 let pat = self.parse_top_level_pat()?;
3504 if !self.eat_keyword(keywords::In) {
3505 let in_span = self.prev_span.between(self.span);
3506 let mut err = self.sess.span_diagnostic
3507 .struct_span_err(in_span, "missing `in` in `for` loop");
3508 err.span_suggestion_short_with_applicability(
3509 in_span, "try adding `in` here", " in ".into(),
3510 // has been misleading, at least in the past (closed Issue #48492)
3511 Applicability::MaybeIncorrect
3515 let in_span = self.prev_span;
3516 if self.eat_keyword(keywords::In) {
3517 // a common typo: `for _ in in bar {}`
3518 let mut err = self.sess.span_diagnostic.struct_span_err(
3520 "expected iterable, found keyword `in`",
3522 err.span_suggestion_short_with_applicability(
3523 in_span.until(self.prev_span),
3524 "remove the duplicated `in`",
3526 Applicability::MachineApplicable,
3528 err.note("if you meant to use emplacement syntax, it is obsolete (for now, anyway)");
3529 err.note("for more information on the status of emplacement syntax, see <\
3530 https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>");
3533 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3534 let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
3535 attrs.extend(iattrs);
3537 let hi = self.prev_span;
3538 Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
3541 /// Parse a 'while' or 'while let' expression ('while' token already eaten)
3542 fn parse_while_expr(&mut self, opt_label: Option<Label>,
3544 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3545 if self.token.is_keyword(keywords::Let) {
3546 return self.parse_while_let_expr(opt_label, span_lo, attrs);
3548 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3549 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3550 attrs.extend(iattrs);
3551 let span = span_lo.to(body.span);
3552 return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs));
3555 /// Parse a 'while let' expression ('while' token already eaten)
3556 fn parse_while_let_expr(&mut self, opt_label: Option<Label>,
3558 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3559 self.expect_keyword(keywords::Let)?;
3560 let pats = self.parse_pats()?;
3561 self.expect(&token::Eq)?;
3562 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3563 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3564 attrs.extend(iattrs);
3565 let span = span_lo.to(body.span);
3566 return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
3569 // parse `loop {...}`, `loop` token already eaten
3570 fn parse_loop_expr(&mut self, opt_label: Option<Label>,
3572 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3573 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3574 attrs.extend(iattrs);
3575 let span = span_lo.to(body.span);
3576 Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
3579 /// Parse an `async move {...}` expression
3580 pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>)
3581 -> PResult<'a, P<Expr>>
3583 let span_lo = self.span;
3584 self.expect_keyword(keywords::Async)?;
3585 let capture_clause = if self.eat_keyword(keywords::Move) {
3590 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3591 attrs.extend(iattrs);
3593 span_lo.to(body.span),
3594 ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs))
3597 /// Parse a `try {...}` expression (`try` token already eaten)
3598 fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
3599 -> PResult<'a, P<Expr>>
3601 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3602 attrs.extend(iattrs);
3603 Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
3606 // `match` token already eaten
3607 fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3608 let match_span = self.prev_span;
3609 let lo = self.prev_span;
3610 let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL,
3612 if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
3613 if self.token == token::Token::Semi {
3614 e.span_suggestion_short_with_applicability(
3616 "try removing this `match`",
3618 Applicability::MaybeIncorrect // speculative
3623 attrs.extend(self.parse_inner_attributes()?);
3625 let mut arms: Vec<Arm> = Vec::new();
3626 while self.token != token::CloseDelim(token::Brace) {
3627 match self.parse_arm() {
3628 Ok(arm) => arms.push(arm),
3630 // Recover by skipping to the end of the block.
3632 self.recover_stmt();
3633 let span = lo.to(self.span);
3634 if self.token == token::CloseDelim(token::Brace) {
3637 return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
3643 return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
3646 crate fn parse_arm(&mut self) -> PResult<'a, Arm> {
3647 maybe_whole!(self, NtArm, |x| x);
3649 let attrs = self.parse_outer_attributes()?;
3650 // Allow a '|' before the pats (RFC 1925)
3651 self.eat(&token::BinOp(token::Or));
3652 let pats = self.parse_pats()?;
3653 let guard = if self.eat_keyword(keywords::If) {
3654 Some(Guard::If(self.parse_expr()?))
3658 let arrow_span = self.span;
3659 self.expect(&token::FatArrow)?;
3660 let arm_start_span = self.span;
3662 let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
3663 .map_err(|mut err| {
3664 err.span_label(arrow_span, "while parsing the `match` arm starting here");
3668 let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
3669 && self.token != token::CloseDelim(token::Brace);
3672 let cm = self.sess.source_map();
3673 self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
3674 .map_err(|mut err| {
3675 match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
3676 (Ok(ref expr_lines), Ok(ref arm_start_lines))
3677 if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
3678 && expr_lines.lines.len() == 2
3679 && self.token == token::FatArrow => {
3680 // We check whether there's any trailing code in the parse span,
3681 // if there isn't, we very likely have the following:
3684 // | -- - missing comma
3690 // | parsed until here as `"y" & X`
3691 err.span_suggestion_short_with_applicability(
3692 cm.next_point(arm_start_span),
3693 "missing a comma here to end this `match` arm",
3695 Applicability::MachineApplicable
3699 err.span_label(arrow_span,
3700 "while parsing the `match` arm starting here");
3706 self.eat(&token::Comma);
3717 /// Parse an expression
3719 pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
3720 self.parse_expr_res(Restrictions::empty(), None)
3723 /// Evaluate the closure with restrictions in place.
3725 /// After the closure is evaluated, restrictions are reset.
3726 fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T
3727 where F: FnOnce(&mut Self) -> T
3729 let old = self.restrictions;
3730 self.restrictions = r;
3732 self.restrictions = old;
3737 /// Parse an expression, subject to the given restrictions
3739 fn parse_expr_res(&mut self, r: Restrictions,
3740 already_parsed_attrs: Option<ThinVec<Attribute>>)
3741 -> PResult<'a, P<Expr>> {
3742 self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
3745 /// Parse the RHS of a local variable declaration (e.g., '= 14;')
3746 fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
3747 if self.eat(&token::Eq) {
3748 Ok(Some(self.parse_expr()?))
3750 Ok(Some(self.parse_expr()?))
3756 /// Parse patterns, separated by '|' s
3757 fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3758 let mut pats = Vec::new();
3760 pats.push(self.parse_top_level_pat()?);
3762 if self.token == token::OrOr {
3763 let mut err = self.struct_span_err(self.span,
3764 "unexpected token `||` after pattern");
3765 err.span_suggestion_with_applicability(
3767 "use a single `|` to specify multiple patterns",
3769 Applicability::MachineApplicable
3773 } else if self.eat(&token::BinOp(token::Or)) {
3781 // Parses a parenthesized list of patterns like
3782 // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns:
3783 // - a vector of the patterns that were parsed
3784 // - an option indicating the index of the `..` element
3785 // - a boolean indicating whether a trailing comma was present.
3786 // Trailing commas are significant because (p) and (p,) are different patterns.
3787 fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3788 self.expect(&token::OpenDelim(token::Paren))?;
3789 let result = self.parse_pat_list()?;
3790 self.expect(&token::CloseDelim(token::Paren))?;
3794 fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3795 let mut fields = Vec::new();
3796 let mut ddpos = None;
3797 let mut trailing_comma = false;
3799 if self.eat(&token::DotDot) {
3800 if ddpos.is_none() {
3801 ddpos = Some(fields.len());
3803 // Emit a friendly error, ignore `..` and continue parsing
3804 self.span_err(self.prev_span,
3805 "`..` can only be used once per tuple or tuple struct pattern");
3807 } else if !self.check(&token::CloseDelim(token::Paren)) {
3808 fields.push(self.parse_pat(None)?);
3813 trailing_comma = self.eat(&token::Comma);
3814 if !trailing_comma {
3819 if ddpos == Some(fields.len()) && trailing_comma {
3820 // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
3821 self.span_err(self.prev_span, "trailing comma is not permitted after `..`");
3824 Ok((fields, ddpos, trailing_comma))
3827 fn parse_pat_vec_elements(
3829 ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3830 let mut before = Vec::new();
3831 let mut slice = None;
3832 let mut after = Vec::new();
3833 let mut first = true;
3834 let mut before_slice = true;
3836 while self.token != token::CloseDelim(token::Bracket) {
3840 self.expect(&token::Comma)?;
3842 if self.token == token::CloseDelim(token::Bracket)
3843 && (before_slice || !after.is_empty()) {
3849 if self.eat(&token::DotDot) {
3851 if self.check(&token::Comma) ||
3852 self.check(&token::CloseDelim(token::Bracket)) {
3853 slice = Some(P(Pat {
3854 id: ast::DUMMY_NODE_ID,
3855 node: PatKind::Wild,
3856 span: self.prev_span,
3858 before_slice = false;
3864 let subpat = self.parse_pat(None)?;
3865 if before_slice && self.eat(&token::DotDot) {
3866 slice = Some(subpat);
3867 before_slice = false;
3868 } else if before_slice {
3869 before.push(subpat);
3875 Ok((before, slice, after))
3881 attrs: Vec<Attribute>
3882 ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> {
3883 // Check if a colon exists one ahead. This means we're parsing a fieldname.
3885 let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3886 // Parsing a pattern of the form "fieldname: pat"
3887 let fieldname = self.parse_field_name()?;
3889 let pat = self.parse_pat(None)?;
3891 (pat, fieldname, false)
3893 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3894 let is_box = self.eat_keyword(keywords::Box);
3895 let boxed_span = self.span;
3896 let is_ref = self.eat_keyword(keywords::Ref);
3897 let is_mut = self.eat_keyword(keywords::Mut);
3898 let fieldname = self.parse_ident()?;
3899 hi = self.prev_span;
3901 let bind_type = match (is_ref, is_mut) {
3902 (true, true) => BindingMode::ByRef(Mutability::Mutable),
3903 (true, false) => BindingMode::ByRef(Mutability::Immutable),
3904 (false, true) => BindingMode::ByValue(Mutability::Mutable),
3905 (false, false) => BindingMode::ByValue(Mutability::Immutable),
3907 let fieldpat = P(Pat {
3908 id: ast::DUMMY_NODE_ID,
3909 node: PatKind::Ident(bind_type, fieldname, None),
3910 span: boxed_span.to(hi),
3913 let subpat = if is_box {
3915 id: ast::DUMMY_NODE_ID,
3916 node: PatKind::Box(fieldpat),
3922 (subpat, fieldname, true)
3925 Ok(source_map::Spanned {
3927 node: ast::FieldPat {
3931 attrs: attrs.into(),
3936 /// Parse the fields of a struct-like pattern
3937 fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> {
3938 let mut fields = Vec::new();
3939 let mut etc = false;
3940 let mut ate_comma = true;
3941 let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
3942 let mut etc_span = None;
3944 while self.token != token::CloseDelim(token::Brace) {
3945 let attrs = self.parse_outer_attributes()?;
3948 // check that a comma comes after every field
3950 let err = self.struct_span_err(self.prev_span, "expected `,`");
3951 if let Some(mut delayed) = delayed_err {
3958 if self.check(&token::DotDot) || self.token == token::DotDotDot {
3960 let mut etc_sp = self.span;
3962 if self.token == token::DotDotDot { // Issue #46718
3963 // Accept `...` as if it were `..` to avoid further errors
3964 let mut err = self.struct_span_err(self.span,
3965 "expected field pattern, found `...`");
3966 err.span_suggestion_with_applicability(
3968 "to omit remaining fields, use one fewer `.`",
3970 Applicability::MachineApplicable
3974 self.bump(); // `..` || `...`
3976 if self.token == token::CloseDelim(token::Brace) {
3977 etc_span = Some(etc_sp);
3980 let token_str = self.this_token_descr();
3981 let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
3983 err.span_label(self.span, "expected `}`");
3984 let mut comma_sp = None;
3985 if self.token == token::Comma { // Issue #49257
3986 etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span));
3987 err.span_label(etc_sp,
3988 "`..` must be at the end and cannot have a trailing comma");
3989 comma_sp = Some(self.span);
3994 etc_span = Some(etc_sp.until(self.span));
3995 if self.token == token::CloseDelim(token::Brace) {
3996 // If the struct looks otherwise well formed, recover and continue.
3997 if let Some(sp) = comma_sp {
3998 err.span_suggestion_short_with_applicability(
4000 "remove this comma",
4002 Applicability::MachineApplicable,
4007 } else if self.token.is_ident() && ate_comma {
4008 // Accept fields coming after `..,`.
4009 // This way we avoid "pattern missing fields" errors afterwards.
4010 // We delay this error until the end in order to have a span for a
4012 if let Some(mut delayed_err) = delayed_err {
4016 delayed_err = Some(err);
4019 if let Some(mut err) = delayed_err {
4026 fields.push(match self.parse_pat_field(lo, attrs) {
4029 if let Some(mut delayed_err) = delayed_err {
4035 ate_comma = self.eat(&token::Comma);
4038 if let Some(mut err) = delayed_err {
4039 if let Some(etc_span) = etc_span {
4040 err.multipart_suggestion(
4041 "move the `..` to the end of the field list",
4043 (etc_span, String::new()),
4044 (self.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
4050 return Ok((fields, etc));
4053 fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
4054 if self.token.is_path_start() {
4056 let (qself, path) = if self.eat_lt() {
4057 // Parse a qualified path
4058 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4061 // Parse an unqualified path
4062 (None, self.parse_path(PathStyle::Expr)?)
4064 let hi = self.prev_span;
4065 Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
4067 self.parse_literal_maybe_minus()
4071 // helper function to decide whether to parse as ident binding or to try to do
4072 // something more complex like range patterns
4073 fn parse_as_ident(&mut self) -> bool {
4074 self.look_ahead(1, |t| match *t {
4075 token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
4076 token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false),
4077 // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the
4078 // range pattern branch
4079 token::DotDot => None,
4081 }).unwrap_or_else(|| self.look_ahead(2, |t| match *t {
4082 token::Comma | token::CloseDelim(token::Bracket) => true,
4087 /// A wrapper around `parse_pat` with some special error handling for the
4088 /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
4089 /// to subpatterns within such).
4090 fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
4091 let pat = self.parse_pat(None)?;
4092 if self.token == token::Comma {
4093 // An unexpected comma after a top-level pattern is a clue that the
4094 // user (perhaps more accustomed to some other language) forgot the
4095 // parentheses in what should have been a tuple pattern; return a
4096 // suggestion-enhanced error here rather than choking on the comma
4098 let comma_span = self.span;
4100 if let Err(mut err) = self.parse_pat_list() {
4101 // We didn't expect this to work anyway; we just wanted
4102 // to advance to the end of the comma-sequence so we know
4103 // the span to suggest parenthesizing
4106 let seq_span = pat.span.to(self.prev_span);
4107 let mut err = self.struct_span_err(comma_span,
4108 "unexpected `,` in pattern");
4109 if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) {
4110 err.span_suggestion_with_applicability(
4112 "try adding parentheses",
4113 format!("({})", seq_snippet),
4114 Applicability::MachineApplicable
4122 /// Parse a pattern.
4123 pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
4124 self.parse_pat_with_range_pat(true, expected)
4127 /// Parse a pattern, with a setting whether modern range patterns e.g., `a..=b`, `a..b` are
4129 fn parse_pat_with_range_pat(
4131 allow_range_pat: bool,
4132 expected: Option<&'static str>,
4133 ) -> PResult<'a, P<Pat>> {
4134 maybe_whole!(self, NtPat, |x| x);
4139 token::BinOp(token::And) | token::AndAnd => {
4140 // Parse &pat / &mut pat
4142 let mutbl = self.parse_mutability();
4143 if let token::Lifetime(ident) = self.token {
4144 let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern",
4146 err.span_label(self.span, "unexpected lifetime");
4149 let subpat = self.parse_pat_with_range_pat(false, expected)?;
4150 pat = PatKind::Ref(subpat, mutbl);
4152 token::OpenDelim(token::Paren) => {
4153 // Parse (pat,pat,pat,...) as tuple pattern
4154 let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?;
4155 pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma {
4156 PatKind::Paren(fields.into_iter().nth(0).unwrap())
4158 PatKind::Tuple(fields, ddpos)
4161 token::OpenDelim(token::Bracket) => {
4162 // Parse [pat,pat,...] as slice pattern
4164 let (before, slice, after) = self.parse_pat_vec_elements()?;
4165 self.expect(&token::CloseDelim(token::Bracket))?;
4166 pat = PatKind::Slice(before, slice, after);
4168 // At this point, token != &, &&, (, [
4169 _ => if self.eat_keyword(keywords::Underscore) {
4171 pat = PatKind::Wild;
4172 } else if self.eat_keyword(keywords::Mut) {
4173 // Parse mut ident @ pat / mut ref ident @ pat
4174 let mutref_span = self.prev_span.to(self.span);
4175 let binding_mode = if self.eat_keyword(keywords::Ref) {
4177 .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
4178 .span_suggestion_with_applicability(
4180 "try switching the order",
4182 Applicability::MachineApplicable
4184 BindingMode::ByRef(Mutability::Mutable)
4186 BindingMode::ByValue(Mutability::Mutable)
4188 pat = self.parse_pat_ident(binding_mode)?;
4189 } else if self.eat_keyword(keywords::Ref) {
4190 // Parse ref ident @ pat / ref mut ident @ pat
4191 let mutbl = self.parse_mutability();
4192 pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
4193 } else if self.eat_keyword(keywords::Box) {
4195 let subpat = self.parse_pat_with_range_pat(false, None)?;
4196 pat = PatKind::Box(subpat);
4197 } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
4198 self.parse_as_ident() {
4199 // Parse ident @ pat
4200 // This can give false positives and parse nullary enums,
4201 // they are dealt with later in resolve
4202 let binding_mode = BindingMode::ByValue(Mutability::Immutable);
4203 pat = self.parse_pat_ident(binding_mode)?;
4204 } else if self.token.is_path_start() {
4205 // Parse pattern starting with a path
4206 let (qself, path) = if self.eat_lt() {
4207 // Parse a qualified path
4208 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4211 // Parse an unqualified path
4212 (None, self.parse_path(PathStyle::Expr)?)
4215 token::Not if qself.is_none() => {
4216 // Parse macro invocation
4218 let (delim, tts) = self.expect_delimited_token_tree()?;
4219 let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim });
4220 pat = PatKind::Mac(mac);
4222 token::DotDotDot | token::DotDotEq | token::DotDot => {
4223 let end_kind = match self.token {
4224 token::DotDot => RangeEnd::Excluded,
4225 token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot),
4226 token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq),
4227 _ => panic!("can only parse `..`/`...`/`..=` for ranges \
4230 let op_span = self.span;
4232 let span = lo.to(self.prev_span);
4233 let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
4235 let end = self.parse_pat_range_end()?;
4236 let op = Spanned { span: op_span, node: end_kind };
4237 pat = PatKind::Range(begin, end, op);
4239 token::OpenDelim(token::Brace) => {
4240 if qself.is_some() {
4241 let msg = "unexpected `{` after qualified path";
4242 let mut err = self.fatal(msg);
4243 err.span_label(self.span, msg);
4246 // Parse struct pattern
4248 let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
4250 self.recover_stmt();
4254 pat = PatKind::Struct(path, fields, etc);
4256 token::OpenDelim(token::Paren) => {
4257 if qself.is_some() {
4258 let msg = "unexpected `(` after qualified path";
4259 let mut err = self.fatal(msg);
4260 err.span_label(self.span, msg);
4263 // Parse tuple struct or enum pattern
4264 let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?;
4265 pat = PatKind::TupleStruct(path, fields, ddpos)
4267 _ => pat = PatKind::Path(qself, path),
4270 // Try to parse everything else as literal with optional minus
4271 match self.parse_literal_maybe_minus() {
4273 let op_span = self.span;
4274 if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
4275 self.check(&token::DotDotDot) {
4276 let end_kind = if self.eat(&token::DotDotDot) {
4277 RangeEnd::Included(RangeSyntax::DotDotDot)
4278 } else if self.eat(&token::DotDotEq) {
4279 RangeEnd::Included(RangeSyntax::DotDotEq)
4280 } else if self.eat(&token::DotDot) {
4283 panic!("impossible case: we already matched \
4284 on a range-operator token")
4286 let end = self.parse_pat_range_end()?;
4287 let op = Spanned { span: op_span, node: end_kind };
4288 pat = PatKind::Range(begin, end, op);
4290 pat = PatKind::Lit(begin);
4294 self.cancel(&mut err);
4295 let expected = expected.unwrap_or("pattern");
4297 "expected {}, found {}",
4299 self.this_token_descr(),
4301 let mut err = self.fatal(&msg);
4302 err.span_label(self.span, format!("expected {}", expected));
4309 let pat = Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID };
4310 let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
4312 if !allow_range_pat {
4315 _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
4317 PatKind::Range(..) => {
4318 let mut err = self.struct_span_err(
4320 "the range pattern here has ambiguous interpretation",
4322 err.span_suggestion_with_applicability(
4324 "add parentheses to clarify the precedence",
4325 format!("({})", pprust::pat_to_string(&pat)),
4326 // "ambiguous interpretation" implies that we have to be guessing
4327 Applicability::MaybeIncorrect
4338 /// Parse ident or ident @ pat
4339 /// used by the copy foo and ref foo patterns to give a good
4340 /// error message when parsing mistakes like ref foo(a,b)
4341 fn parse_pat_ident(&mut self,
4342 binding_mode: ast::BindingMode)
4343 -> PResult<'a, PatKind> {
4344 let ident = self.parse_ident()?;
4345 let sub = if self.eat(&token::At) {
4346 Some(self.parse_pat(Some("binding pattern"))?)
4351 // just to be friendly, if they write something like
4353 // we end up here with ( as the current token. This shortly
4354 // leads to a parse error. Note that if there is no explicit
4355 // binding mode then we do not end up here, because the lookahead
4356 // will direct us over to parse_enum_variant()
4357 if self.token == token::OpenDelim(token::Paren) {
4358 return Err(self.span_fatal(
4360 "expected identifier, found enum pattern"))
4363 Ok(PatKind::Ident(binding_mode, ident, sub))
4366 /// Parse a local variable declaration
4367 fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
4368 let lo = self.prev_span;
4369 let pat = self.parse_top_level_pat()?;
4371 let (err, ty) = if self.eat(&token::Colon) {
4372 // Save the state of the parser before parsing type normally, in case there is a `:`
4373 // instead of an `=` typo.
4374 let parser_snapshot_before_type = self.clone();
4375 let colon_sp = self.prev_span;
4376 match self.parse_ty() {
4377 Ok(ty) => (None, Some(ty)),
4379 // Rewind to before attempting to parse the type and continue parsing
4380 let parser_snapshot_after_type = self.clone();
4381 mem::replace(self, parser_snapshot_before_type);
4383 let snippet = self.sess.source_map().span_to_snippet(pat.span).unwrap();
4384 err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
4385 (Some((parser_snapshot_after_type, colon_sp, err)), None)
4391 let init = match (self.parse_initializer(err.is_some()), err) {
4392 (Ok(init), None) => { // init parsed, ty parsed
4395 (Ok(init), Some((_, colon_sp, mut err))) => { // init parsed, ty error
4396 // Could parse the type as if it were the initializer, it is likely there was a
4397 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
4398 err.span_suggestion_short_with_applicability(
4400 "use `=` if you meant to assign",
4402 Applicability::MachineApplicable
4405 // As this was parsed successfully, continue as if the code has been fixed for the
4406 // rest of the file. It will still fail due to the emitted error, but we avoid
4410 (Err(mut init_err), Some((snapshot, _, ty_err))) => { // init error, ty error
4412 // Couldn't parse the type nor the initializer, only raise the type error and
4413 // return to the parser state before parsing the type as the initializer.
4414 // let x: <parse_error>;
4415 mem::replace(self, snapshot);
4418 (Err(err), None) => { // init error, ty parsed
4419 // Couldn't parse the initializer and we're not attempting to recover a failed
4420 // parse of the type, return the error.
4424 let hi = if self.token == token::Semi {
4433 id: ast::DUMMY_NODE_ID,
4439 /// Parse a structure field
4440 fn parse_name_and_ty(&mut self,
4443 attrs: Vec<Attribute>)
4444 -> PResult<'a, StructField> {
4445 let name = self.parse_ident()?;
4446 self.expect(&token::Colon)?;
4447 let ty = self.parse_ty()?;
4449 span: lo.to(self.prev_span),
4452 id: ast::DUMMY_NODE_ID,
4458 /// Emit an expected item after attributes error.
4459 fn expected_item_err(&self, attrs: &[Attribute]) {
4460 let message = match attrs.last() {
4461 Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
4462 _ => "expected item after attributes",
4465 self.span_err(self.prev_span, message);
4468 /// Parse a statement. This stops just before trailing semicolons on everything but items.
4469 /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
4470 pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
4471 Ok(self.parse_stmt_(true))
4474 // Eat tokens until we can be relatively sure we reached the end of the
4475 // statement. This is something of a best-effort heuristic.
4477 // We terminate when we find an unmatched `}` (without consuming it).
4478 fn recover_stmt(&mut self) {
4479 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
4482 // If `break_on_semi` is `Break`, then we will stop consuming tokens after
4483 // finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
4484 // approximate - it can mean we break too early due to macros, but that
4485 // should only lead to sub-optimal recovery, not inaccurate parsing).
4487 // If `break_on_block` is `Break`, then we will stop consuming tokens
4488 // after finding (and consuming) a brace-delimited block.
4489 fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) {
4490 let mut brace_depth = 0;
4491 let mut bracket_depth = 0;
4492 let mut in_block = false;
4493 debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
4494 break_on_semi, break_on_block);
4496 debug!("recover_stmt_ loop {:?}", self.token);
4498 token::OpenDelim(token::DelimToken::Brace) => {
4501 if break_on_block == BlockMode::Break &&
4503 bracket_depth == 0 {
4507 token::OpenDelim(token::DelimToken::Bracket) => {
4511 token::CloseDelim(token::DelimToken::Brace) => {
4512 if brace_depth == 0 {
4513 debug!("recover_stmt_ return - close delim {:?}", self.token);
4518 if in_block && bracket_depth == 0 && brace_depth == 0 {
4519 debug!("recover_stmt_ return - block end {:?}", self.token);
4523 token::CloseDelim(token::DelimToken::Bracket) => {
4525 if bracket_depth < 0 {
4531 debug!("recover_stmt_ return - Eof");
4536 if break_on_semi == SemiColonMode::Break &&
4538 bracket_depth == 0 {
4539 debug!("recover_stmt_ return - Semi");
4550 fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
4551 self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
4553 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4558 fn is_async_block(&mut self) -> bool {
4559 self.token.is_keyword(keywords::Async) &&
4562 self.look_ahead(1, |t| t.is_keyword(keywords::Move)) &&
4563 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
4565 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
4570 fn is_do_catch_block(&mut self) -> bool {
4571 self.token.is_keyword(keywords::Do) &&
4572 self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) &&
4573 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
4574 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4577 fn is_try_block(&mut self) -> bool {
4578 self.token.is_keyword(keywords::Try) &&
4579 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
4580 self.span.rust_2018() &&
4581 // prevent `while try {} {}`, `if try {} {} else {}`, etc.
4582 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4585 fn is_union_item(&self) -> bool {
4586 self.token.is_keyword(keywords::Union) &&
4587 self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
4590 fn is_crate_vis(&self) -> bool {
4591 self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
4594 fn is_extern_non_path(&self) -> bool {
4595 self.token.is_keyword(keywords::Extern) && self.look_ahead(1, |t| t != &token::ModSep)
4598 fn is_existential_type_decl(&self) -> bool {
4599 self.token.is_keyword(keywords::Existential) &&
4600 self.look_ahead(1, |t| t.is_keyword(keywords::Type))
4603 fn is_auto_trait_item(&mut self) -> bool {
4605 (self.token.is_keyword(keywords::Auto)
4606 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
4607 || // unsafe auto trait
4608 (self.token.is_keyword(keywords::Unsafe) &&
4609 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) &&
4610 self.look_ahead(2, |t| t.is_keyword(keywords::Trait)))
4613 fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span)
4614 -> PResult<'a, Option<P<Item>>> {
4615 let token_lo = self.span;
4616 let (ident, def) = match self.token {
4617 token::Ident(ident, false) if ident.name == keywords::Macro.name() => {
4619 let ident = self.parse_ident()?;
4620 let tokens = if self.check(&token::OpenDelim(token::Brace)) {
4621 match self.parse_token_tree() {
4622 TokenTree::Delimited(_, _, tts) => tts.stream(),
4623 _ => unreachable!(),
4625 } else if self.check(&token::OpenDelim(token::Paren)) {
4626 let args = self.parse_token_tree();
4627 let body = if self.check(&token::OpenDelim(token::Brace)) {
4628 self.parse_token_tree()
4633 TokenStream::new(vec![
4635 TokenTree::Token(token_lo.to(self.prev_span), token::FatArrow).into(),
4643 (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
4645 token::Ident(ident, _) if ident.name == "macro_rules" &&
4646 self.look_ahead(1, |t| *t == token::Not) => {
4647 let prev_span = self.prev_span;
4648 self.complain_if_pub_macro(&vis.node, prev_span);
4652 let ident = self.parse_ident()?;
4653 let (delim, tokens) = self.expect_delimited_token_tree()?;
4654 if delim != MacDelimiter::Brace {
4655 if !self.eat(&token::Semi) {
4656 let msg = "macros that expand to items must either \
4657 be surrounded with braces or followed by a semicolon";
4658 self.span_err(self.prev_span, msg);
4662 (ident, ast::MacroDef { tokens: tokens, legacy: true })
4664 _ => return Ok(None),
4667 let span = lo.to(self.prev_span);
4668 Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
4671 fn parse_stmt_without_recovery(&mut self,
4672 macro_legacy_warnings: bool)
4673 -> PResult<'a, Option<Stmt>> {
4674 maybe_whole!(self, NtStmt, |x| Some(x));
4676 let attrs = self.parse_outer_attributes()?;
4679 Ok(Some(if self.eat_keyword(keywords::Let) {
4681 id: ast::DUMMY_NODE_ID,
4682 node: StmtKind::Local(self.parse_local(attrs.into())?),
4683 span: lo.to(self.prev_span),
4685 } else if let Some(macro_def) = self.eat_macro_def(
4687 &source_map::respan(lo, VisibilityKind::Inherited),
4691 id: ast::DUMMY_NODE_ID,
4692 node: StmtKind::Item(macro_def),
4693 span: lo.to(self.prev_span),
4695 // Starts like a simple path, being careful to avoid contextual keywords
4696 // such as a union items, item with `crate` visibility or auto trait items.
4697 // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
4698 // like a path (1 token), but it fact not a path.
4699 // `union::b::c` - path, `union U { ... }` - not a path.
4700 // `crate::b::c` - path, `crate struct S;` - not a path.
4701 // `extern::b::c` - path, `extern crate c;` - not a path.
4702 } else if self.token.is_path_start() &&
4703 !self.token.is_qpath_start() &&
4704 !self.is_union_item() &&
4705 !self.is_crate_vis() &&
4706 !self.is_extern_non_path() &&
4707 !self.is_existential_type_decl() &&
4708 !self.is_auto_trait_item() {
4709 let pth = self.parse_path(PathStyle::Expr)?;
4711 if !self.eat(&token::Not) {
4712 let expr = if self.check(&token::OpenDelim(token::Brace)) {
4713 self.parse_struct_expr(lo, pth, ThinVec::new())?
4715 let hi = self.prev_span;
4716 self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), ThinVec::new())
4719 let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
4720 let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
4721 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
4724 return Ok(Some(Stmt {
4725 id: ast::DUMMY_NODE_ID,
4726 node: StmtKind::Expr(expr),
4727 span: lo.to(self.prev_span),
4731 // it's a macro invocation
4732 let id = match self.token {
4733 token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier
4734 _ => self.parse_ident()?,
4737 // check that we're pointing at delimiters (need to check
4738 // again after the `if`, because of `parse_ident`
4739 // consuming more tokens).
4741 token::OpenDelim(_) => {}
4743 // we only expect an ident if we didn't parse one
4745 let ident_str = if id.name == keywords::Invalid.name() {
4750 let tok_str = self.this_token_descr();
4751 let mut err = self.fatal(&format!("expected {}`(` or `{{`, found {}",
4754 err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str));
4759 let (delim, tts) = self.expect_delimited_token_tree()?;
4760 let hi = self.prev_span;
4762 let style = if delim == MacDelimiter::Brace {
4763 MacStmtStyle::Braces
4765 MacStmtStyle::NoBraces
4768 if id.name == keywords::Invalid.name() {
4769 let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim });
4770 let node = if delim == MacDelimiter::Brace ||
4771 self.token == token::Semi || self.token == token::Eof {
4772 StmtKind::Mac(P((mac, style, attrs.into())))
4774 // We used to incorrectly stop parsing macro-expanded statements here.
4775 // If the next token will be an error anyway but could have parsed with the
4776 // earlier behavior, stop parsing here and emit a warning to avoid breakage.
4777 else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token {
4778 // These can continue an expression, so we can't stop parsing and warn.
4779 token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
4780 token::BinOp(token::Minus) | token::BinOp(token::Star) |
4781 token::BinOp(token::And) | token::BinOp(token::Or) |
4782 token::AndAnd | token::OrOr |
4783 token::DotDot | token::DotDotDot | token::DotDotEq => false,
4786 self.warn_missing_semicolon();
4787 StmtKind::Mac(P((mac, style, attrs.into())))
4789 let e = self.mk_mac_expr(lo.to(hi), mac.node, ThinVec::new());
4790 let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
4791 let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
4795 id: ast::DUMMY_NODE_ID,
4800 // if it has a special ident, it's definitely an item
4802 // Require a semicolon or braces.
4803 if style != MacStmtStyle::Braces {
4804 if !self.eat(&token::Semi) {
4805 self.span_err(self.prev_span,
4806 "macros that expand to items must \
4807 either be surrounded with braces or \
4808 followed by a semicolon");
4811 let span = lo.to(hi);
4813 id: ast::DUMMY_NODE_ID,
4815 node: StmtKind::Item({
4817 span, id /*id is good here*/,
4818 ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })),
4819 respan(lo, VisibilityKind::Inherited),
4825 // FIXME: Bad copy of attrs
4826 let old_directory_ownership =
4827 mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
4828 let item = self.parse_item_(attrs.clone(), false, true)?;
4829 self.directory.ownership = old_directory_ownership;
4833 id: ast::DUMMY_NODE_ID,
4834 span: lo.to(i.span),
4835 node: StmtKind::Item(i),
4838 let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
4839 if !attrs.is_empty() {
4840 if s.prev_token_kind == PrevTokenKind::DocComment {
4841 s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
4842 } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
4843 s.span_err(s.span, "expected statement after outer attribute");
4848 // Do not attempt to parse an expression if we're done here.
4849 if self.token == token::Semi {
4850 unused_attrs(&attrs, self);
4855 if self.token == token::CloseDelim(token::Brace) {
4856 unused_attrs(&attrs, self);
4860 // Remainder are line-expr stmts.
4861 let e = self.parse_expr_res(
4862 Restrictions::STMT_EXPR, Some(attrs.into()))?;
4864 id: ast::DUMMY_NODE_ID,
4865 span: lo.to(e.span),
4866 node: StmtKind::Expr(e),
4873 /// Is this expression a successfully-parsed statement?
4874 fn expr_is_complete(&mut self, e: &Expr) -> bool {
4875 self.restrictions.contains(Restrictions::STMT_EXPR) &&
4876 !classify::expr_requires_semi_to_be_stmt(e)
4879 /// Parse a block. No inner attrs are allowed.
4880 pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
4881 maybe_whole!(self, NtBlock, |x| x);
4885 if !self.eat(&token::OpenDelim(token::Brace)) {
4887 let tok = self.this_token_descr();
4888 let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok));
4889 let do_not_suggest_help =
4890 self.token.is_keyword(keywords::In) || self.token == token::Colon;
4892 if self.token.is_ident_named("and") {
4893 e.span_suggestion_short_with_applicability(
4895 "use `&&` instead of `and` for the boolean operator",
4897 Applicability::MaybeIncorrect,
4900 if self.token.is_ident_named("or") {
4901 e.span_suggestion_short_with_applicability(
4903 "use `||` instead of `or` for the boolean operator",
4905 Applicability::MaybeIncorrect,
4909 // Check to see if the user has written something like
4914 // Which is valid in other languages, but not Rust.
4915 match self.parse_stmt_without_recovery(false) {
4917 if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
4918 || do_not_suggest_help {
4919 // if the next token is an open brace (e.g., `if a b {`), the place-
4920 // inside-a-block suggestion would be more likely wrong than right
4921 e.span_label(sp, "expected `{`");
4924 let mut stmt_span = stmt.span;
4925 // expand the span to include the semicolon, if it exists
4926 if self.eat(&token::Semi) {
4927 stmt_span = stmt_span.with_hi(self.prev_span.hi());
4929 let sugg = pprust::to_string(|s| {
4930 use print::pprust::{PrintState, INDENT_UNIT};
4931 s.ibox(INDENT_UNIT)?;
4933 s.print_stmt(&stmt)?;
4934 s.bclose_maybe_open(stmt.span, INDENT_UNIT, false)
4936 e.span_suggestion_with_applicability(
4938 "try placing this code inside a block",
4940 // speculative, has been misleading in the past (closed Issue #46836)
4941 Applicability::MaybeIncorrect
4945 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4946 self.cancel(&mut e);
4950 e.span_label(sp, "expected `{`");
4954 self.parse_block_tail(lo, BlockCheckMode::Default)
4957 /// Parse a block. Inner attrs are allowed.
4958 fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
4959 maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
4962 self.expect(&token::OpenDelim(token::Brace))?;
4963 Ok((self.parse_inner_attributes()?,
4964 self.parse_block_tail(lo, BlockCheckMode::Default)?))
4967 /// Parse the rest of a block expression or function body
4968 /// Precondition: already parsed the '{'.
4969 fn parse_block_tail(&mut self, lo: Span, s: BlockCheckMode) -> PResult<'a, P<Block>> {
4970 let mut stmts = vec![];
4971 while !self.eat(&token::CloseDelim(token::Brace)) {
4972 let stmt = match self.parse_full_stmt(false) {
4975 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
4977 id: ast::DUMMY_NODE_ID,
4978 node: StmtKind::Expr(DummyResult::raw_expr(self.span, true)),
4984 if let Some(stmt) = stmt {
4986 } else if self.token == token::Eof {
4989 // Found only `;` or `}`.
4995 id: ast::DUMMY_NODE_ID,
4997 span: lo.to(self.prev_span),
5001 /// Parse a statement, including the trailing semicolon.
5002 crate fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
5003 // skip looking for a trailing semicolon when we have an interpolated statement
5004 maybe_whole!(self, NtStmt, |x| Some(x));
5006 let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
5008 None => return Ok(None),
5012 StmtKind::Expr(ref expr) if self.token != token::Eof => {
5013 // expression without semicolon
5014 if classify::expr_requires_semi_to_be_stmt(expr) {
5015 // Just check for errors and recover; do not eat semicolon yet.
5017 self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
5020 self.recover_stmt();
5024 StmtKind::Local(..) => {
5025 // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
5026 if macro_legacy_warnings && self.token != token::Semi {
5027 self.warn_missing_semicolon();
5029 self.expect_one_of(&[], &[token::Semi])?;
5035 if self.eat(&token::Semi) {
5036 stmt = stmt.add_trailing_semicolon();
5039 stmt.span = stmt.span.with_hi(self.prev_span.hi());
5043 fn warn_missing_semicolon(&self) {
5044 self.diagnostic().struct_span_warn(self.span, {
5045 &format!("expected `;`, found {}", self.this_token_descr())
5047 "This was erroneously allowed and will become a hard error in a future release"
5051 fn err_dotdotdot_syntax(&self, span: Span) {
5052 self.diagnostic().struct_span_err(span, {
5053 "unexpected token: `...`"
5054 }).span_suggestion_with_applicability(
5055 span, "use `..` for an exclusive range", "..".to_owned(),
5056 Applicability::MaybeIncorrect
5057 ).span_suggestion_with_applicability(
5058 span, "or `..=` for an inclusive range", "..=".to_owned(),
5059 Applicability::MaybeIncorrect
5063 // Parse bounds of a type parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5064 // BOUND = TY_BOUND | LT_BOUND
5065 // LT_BOUND = LIFETIME (e.g., `'a`)
5066 // TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
5067 // TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
5068 fn parse_generic_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, GenericBounds> {
5069 let mut bounds = Vec::new();
5071 // This needs to be synchronized with `Token::can_begin_bound`.
5072 let is_bound_start = self.check_path() || self.check_lifetime() ||
5073 self.check(&token::Question) ||
5074 self.check_keyword(keywords::For) ||
5075 self.check(&token::OpenDelim(token::Paren));
5078 let has_parens = self.eat(&token::OpenDelim(token::Paren));
5079 let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
5080 if self.token.is_lifetime() {
5081 if let Some(question_span) = question {
5082 self.span_err(question_span,
5083 "`?` may only modify trait bounds, not lifetime bounds");
5085 bounds.push(GenericBound::Outlives(self.expect_lifetime()));
5087 self.expect(&token::CloseDelim(token::Paren))?;
5088 self.span_err(self.prev_span,
5089 "parenthesized lifetime bounds are not supported");
5092 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5093 let path = self.parse_path(PathStyle::Type)?;
5095 self.expect(&token::CloseDelim(token::Paren))?;
5097 let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span));
5098 let modifier = if question.is_some() {
5099 TraitBoundModifier::Maybe
5101 TraitBoundModifier::None
5103 bounds.push(GenericBound::Trait(poly_trait, modifier));
5109 if !allow_plus || !self.eat_plus() {
5117 fn parse_generic_bounds(&mut self) -> PResult<'a, GenericBounds> {
5118 self.parse_generic_bounds_common(true)
5121 // Parse bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5122 // BOUND = LT_BOUND (e.g., `'a`)
5123 fn parse_lt_param_bounds(&mut self) -> GenericBounds {
5124 let mut lifetimes = Vec::new();
5125 while self.check_lifetime() {
5126 lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
5128 if !self.eat_plus() {
5135 /// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
5136 fn parse_ty_param(&mut self,
5137 preceding_attrs: Vec<Attribute>)
5138 -> PResult<'a, GenericParam> {
5139 let ident = self.parse_ident()?;
5141 // Parse optional colon and param bounds.
5142 let bounds = if self.eat(&token::Colon) {
5143 self.parse_generic_bounds()?
5148 let default = if self.eat(&token::Eq) {
5149 Some(self.parse_ty()?)
5156 id: ast::DUMMY_NODE_ID,
5157 attrs: preceding_attrs.into(),
5159 kind: GenericParamKind::Type {
5165 /// Parses the following grammar:
5166 /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
5167 fn parse_trait_item_assoc_ty(&mut self)
5168 -> PResult<'a, (Ident, TraitItemKind, ast::Generics)> {
5169 let ident = self.parse_ident()?;
5170 let mut generics = self.parse_generics()?;
5172 // Parse optional colon and param bounds.
5173 let bounds = if self.eat(&token::Colon) {
5174 self.parse_generic_bounds()?
5178 generics.where_clause = self.parse_where_clause()?;
5180 let default = if self.eat(&token::Eq) {
5181 Some(self.parse_ty()?)
5185 self.expect(&token::Semi)?;
5187 Ok((ident, TraitItemKind::Type(bounds, default), generics))
5190 /// Parses (possibly empty) list of lifetime and type parameters, possibly including
5191 /// trailing comma and erroneous trailing attributes.
5192 crate fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
5193 let mut lifetimes = Vec::new();
5194 let mut params = Vec::new();
5195 let mut seen_ty_param: Option<Span> = None;
5196 let mut last_comma_span = None;
5197 let mut bad_lifetime_pos = vec![];
5198 let mut suggestions = vec![];
5200 let attrs = self.parse_outer_attributes()?;
5201 if self.check_lifetime() {
5202 let lifetime = self.expect_lifetime();
5203 // Parse lifetime parameter.
5204 let bounds = if self.eat(&token::Colon) {
5205 self.parse_lt_param_bounds()
5209 lifetimes.push(ast::GenericParam {
5210 ident: lifetime.ident,
5212 attrs: attrs.into(),
5214 kind: ast::GenericParamKind::Lifetime,
5216 if let Some(sp) = seen_ty_param {
5217 let param_span = self.prev_span;
5218 let ate_comma = self.eat(&token::Comma);
5219 let remove_sp = if ate_comma {
5220 param_span.until(self.span)
5222 last_comma_span.unwrap_or(param_span).to(param_span)
5224 bad_lifetime_pos.push(param_span);
5226 if let Ok(snippet) = self.sess.source_map().span_to_snippet(param_span) {
5227 suggestions.push((remove_sp, String::new()));
5228 suggestions.push((sp.shrink_to_lo(), format!("{}, ", snippet)));
5231 last_comma_span = Some(self.prev_span);
5235 } else if self.check_ident() {
5236 // Parse type parameter.
5237 params.push(self.parse_ty_param(attrs)?);
5238 if seen_ty_param.is_none() {
5239 seen_ty_param = Some(self.prev_span);
5242 // Check for trailing attributes and stop parsing.
5243 if !attrs.is_empty() {
5244 let param_kind = if seen_ty_param.is_some() { "type" } else { "lifetime" };
5245 self.span_err(attrs[0].span,
5246 &format!("trailing attribute after {} parameters", param_kind));
5251 if !self.eat(&token::Comma) {
5254 last_comma_span = Some(self.prev_span);
5256 if !bad_lifetime_pos.is_empty() {
5257 let mut err = self.struct_span_err(
5259 "lifetime parameters must be declared prior to type parameters",
5261 if !suggestions.is_empty() {
5262 err.multipart_suggestion_with_applicability(
5263 "move the lifetime parameter prior to the first type parameter",
5265 Applicability::MachineApplicable,
5270 lifetimes.extend(params); // ensure the correct order of lifetimes and type params
5274 /// Parse a set of optional generic type parameter declarations. Where
5275 /// clauses are not parsed here, and must be added later via
5276 /// `parse_where_clause()`.
5278 /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
5279 /// | ( < lifetimes , typaramseq ( , )? > )
5280 /// where typaramseq = ( typaram ) | ( typaram , typaramseq )
5281 fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
5282 maybe_whole!(self, NtGenerics, |x| x);
5284 let span_lo = self.span;
5286 let params = self.parse_generic_params()?;
5290 where_clause: WhereClause {
5291 id: ast::DUMMY_NODE_ID,
5292 predicates: Vec::new(),
5293 span: syntax_pos::DUMMY_SP,
5295 span: span_lo.to(self.prev_span),
5298 Ok(ast::Generics::default())
5302 /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
5303 /// possibly including trailing comma.
5304 fn parse_generic_args(&mut self)
5305 -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
5306 let mut args = Vec::new();
5307 let mut bindings = Vec::new();
5308 let mut seen_type = false;
5309 let mut seen_binding = false;
5311 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5312 // Parse lifetime argument.
5313 args.push(GenericArg::Lifetime(self.expect_lifetime()));
5314 if seen_type || seen_binding {
5315 self.span_err(self.prev_span,
5316 "lifetime parameters must be declared prior to type parameters");
5318 } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
5319 // Parse associated type binding.
5321 let ident = self.parse_ident()?;
5323 let ty = self.parse_ty()?;
5324 bindings.push(TypeBinding {
5325 id: ast::DUMMY_NODE_ID,
5328 span: lo.to(self.prev_span),
5330 seen_binding = true;
5331 } else if self.check_type() {
5332 // Parse type argument.
5333 let ty_param = self.parse_ty()?;
5335 self.span_err(ty_param.span,
5336 "type parameters must be declared prior to associated type bindings");
5338 args.push(GenericArg::Type(ty_param));
5344 if !self.eat(&token::Comma) {
5348 Ok((args, bindings))
5351 /// Parses an optional `where` clause and places it in `generics`.
5353 /// ```ignore (only-for-syntax-highlight)
5354 /// where T : Trait<U, V> + 'b, 'a : 'b
5356 fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
5357 maybe_whole!(self, NtWhereClause, |x| x);
5359 let mut where_clause = WhereClause {
5360 id: ast::DUMMY_NODE_ID,
5361 predicates: Vec::new(),
5362 span: syntax_pos::DUMMY_SP,
5365 if !self.eat_keyword(keywords::Where) {
5366 return Ok(where_clause);
5368 let lo = self.prev_span;
5370 // We are considering adding generics to the `where` keyword as an alternative higher-rank
5371 // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
5372 // change we parse those generics now, but report an error.
5373 if self.choose_generics_over_qpath() {
5374 let generics = self.parse_generics()?;
5375 self.span_err(generics.span,
5376 "generic parameters on `where` clauses are reserved for future use");
5381 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5382 let lifetime = self.expect_lifetime();
5383 // Bounds starting with a colon are mandatory, but possibly empty.
5384 self.expect(&token::Colon)?;
5385 let bounds = self.parse_lt_param_bounds();
5386 where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
5387 ast::WhereRegionPredicate {
5388 span: lo.to(self.prev_span),
5393 } else if self.check_type() {
5394 // Parse optional `for<'a, 'b>`.
5395 // This `for` is parsed greedily and applies to the whole predicate,
5396 // the bounded type can have its own `for` applying only to it.
5397 // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/>
5398 // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/>
5399 // Example 3: for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /*ok*/, 'b /*not ok*/>
5400 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5402 // Parse type with mandatory colon and (possibly empty) bounds,
5403 // or with mandatory equality sign and the second type.
5404 let ty = self.parse_ty()?;
5405 if self.eat(&token::Colon) {
5406 let bounds = self.parse_generic_bounds()?;
5407 where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
5408 ast::WhereBoundPredicate {
5409 span: lo.to(self.prev_span),
5410 bound_generic_params: lifetime_defs,
5415 // FIXME: Decide what should be used here, `=` or `==`.
5416 // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
5417 } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
5418 let rhs_ty = self.parse_ty()?;
5419 where_clause.predicates.push(ast::WherePredicate::EqPredicate(
5420 ast::WhereEqPredicate {
5421 span: lo.to(self.prev_span),
5424 id: ast::DUMMY_NODE_ID,
5428 return self.unexpected();
5434 if !self.eat(&token::Comma) {
5439 where_clause.span = lo.to(self.prev_span);
5443 fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
5444 -> PResult<'a, (Vec<Arg> , bool)> {
5445 self.expect(&token::OpenDelim(token::Paren))?;
5448 let mut variadic = false;
5449 let args: Vec<Option<Arg>> =
5450 self.parse_seq_to_before_end(
5451 &token::CloseDelim(token::Paren),
5452 SeqSep::trailing_allowed(token::Comma),
5454 if p.token == token::DotDotDot {
5458 if p.token != token::CloseDelim(token::Paren) {
5461 "`...` must be last in argument list for variadic function");
5465 let span = p.prev_span;
5466 if p.token == token::CloseDelim(token::Paren) {
5467 // continue parsing to present any further errors
5470 "only foreign functions are allowed to be variadic"
5472 Ok(Some(dummy_arg(span)))
5474 // this function definition looks beyond recovery, stop parsing
5476 "only foreign functions are allowed to be variadic");
5481 match p.parse_arg_general(named_args, false) {
5482 Ok(arg) => Ok(Some(arg)),
5485 let lo = p.prev_span;
5486 // Skip every token until next possible arg or end.
5487 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
5488 // Create a placeholder argument for proper arg count (#34264).
5489 let span = lo.to(p.prev_span);
5490 Ok(Some(dummy_arg(span)))
5497 self.eat(&token::CloseDelim(token::Paren));
5499 let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
5501 if variadic && args.is_empty() {
5503 "variadic function must be declared with at least one named argument");
5506 Ok((args, variadic))
5509 /// Parse the argument list and result type of a function declaration
5510 fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
5512 let (args, variadic) = self.parse_fn_args(true, allow_variadic)?;
5513 let ret_ty = self.parse_ret_ty(true)?;
5522 /// Returns the parsed optional self argument and whether a self shortcut was used.
5523 fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
5524 let expect_ident = |this: &mut Self| match this.token {
5525 // Preserve hygienic context.
5526 token::Ident(ident, _) =>
5527 { let span = this.span; this.bump(); Ident::new(ident.name, span) }
5530 let isolated_self = |this: &mut Self, n| {
5531 this.look_ahead(n, |t| t.is_keyword(keywords::SelfLower)) &&
5532 this.look_ahead(n + 1, |t| t != &token::ModSep)
5535 // Parse optional self parameter of a method.
5536 // Only a limited set of initial token sequences is considered self parameters, anything
5537 // else is parsed as a normal function parameter list, so some lookahead is required.
5538 let eself_lo = self.span;
5539 let (eself, eself_ident, eself_hi) = match self.token {
5540 token::BinOp(token::And) => {
5546 (if isolated_self(self, 1) {
5548 SelfKind::Region(None, Mutability::Immutable)
5549 } else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
5550 isolated_self(self, 2) {
5553 SelfKind::Region(None, Mutability::Mutable)
5554 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5555 isolated_self(self, 2) {
5557 let lt = self.expect_lifetime();
5558 SelfKind::Region(Some(lt), Mutability::Immutable)
5559 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5560 self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
5561 isolated_self(self, 3) {
5563 let lt = self.expect_lifetime();
5565 SelfKind::Region(Some(lt), Mutability::Mutable)
5568 }, expect_ident(self), self.prev_span)
5570 token::BinOp(token::Star) => {
5575 // Emit special error for `self` cases.
5576 (if isolated_self(self, 1) {
5578 self.span_err(self.span, "cannot pass `self` by raw pointer");
5579 SelfKind::Value(Mutability::Immutable)
5580 } else if self.look_ahead(1, |t| t.is_mutability()) &&
5581 isolated_self(self, 2) {
5584 self.span_err(self.span, "cannot pass `self` by raw pointer");
5585 SelfKind::Value(Mutability::Immutable)
5588 }, expect_ident(self), self.prev_span)
5590 token::Ident(..) => {
5591 if isolated_self(self, 0) {
5594 let eself_ident = expect_ident(self);
5595 let eself_hi = self.prev_span;
5596 (if self.eat(&token::Colon) {
5597 let ty = self.parse_ty()?;
5598 SelfKind::Explicit(ty, Mutability::Immutable)
5600 SelfKind::Value(Mutability::Immutable)
5601 }, eself_ident, eself_hi)
5602 } else if self.token.is_keyword(keywords::Mut) &&
5603 isolated_self(self, 1) {
5607 let eself_ident = expect_ident(self);
5608 let eself_hi = self.prev_span;
5609 (if self.eat(&token::Colon) {
5610 let ty = self.parse_ty()?;
5611 SelfKind::Explicit(ty, Mutability::Mutable)
5613 SelfKind::Value(Mutability::Mutable)
5614 }, eself_ident, eself_hi)
5619 _ => return Ok(None),
5622 let eself = source_map::respan(eself_lo.to(eself_hi), eself);
5623 Ok(Some(Arg::from_self(eself, eself_ident)))
5626 /// Parse the parameter list and result type of a function that may have a `self` parameter.
5627 fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>>
5628 where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
5630 self.expect(&token::OpenDelim(token::Paren))?;
5632 // Parse optional self argument
5633 let self_arg = self.parse_self_arg()?;
5635 // Parse the rest of the function parameter list.
5636 let sep = SeqSep::trailing_allowed(token::Comma);
5637 let fn_inputs = if let Some(self_arg) = self_arg {
5638 if self.check(&token::CloseDelim(token::Paren)) {
5640 } else if self.eat(&token::Comma) {
5641 let mut fn_inputs = vec![self_arg];
5642 fn_inputs.append(&mut self.parse_seq_to_before_end(
5643 &token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5647 return self.unexpected();
5650 self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5653 // Parse closing paren and return type.
5654 self.expect(&token::CloseDelim(token::Paren))?;
5657 output: self.parse_ret_ty(true)?,
5662 // parse the |arg, arg| header on a lambda
5663 fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
5664 let inputs_captures = {
5665 if self.eat(&token::OrOr) {
5668 self.expect(&token::BinOp(token::Or))?;
5669 let args = self.parse_seq_to_before_tokens(
5670 &[&token::BinOp(token::Or), &token::OrOr],
5671 SeqSep::trailing_allowed(token::Comma),
5672 TokenExpectType::NoExpect,
5673 |p| p.parse_fn_block_arg()
5679 let output = self.parse_ret_ty(true)?;
5682 inputs: inputs_captures,
5688 /// Parse the name and optional generic types of a function header.
5689 fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
5690 let id = self.parse_ident()?;
5691 let generics = self.parse_generics()?;
5695 fn mk_item(&mut self, span: Span, ident: Ident, node: ItemKind, vis: Visibility,
5696 attrs: Vec<Attribute>) -> P<Item> {
5700 id: ast::DUMMY_NODE_ID,
5708 /// Parse an item-position function declaration.
5709 fn parse_item_fn(&mut self,
5712 constness: Spanned<Constness>,
5714 -> PResult<'a, ItemInfo> {
5715 let (ident, mut generics) = self.parse_fn_header()?;
5716 let decl = self.parse_fn_decl(false)?;
5717 generics.where_clause = self.parse_where_clause()?;
5718 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5719 let header = FnHeader { unsafety, asyncness, constness, abi };
5720 Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
5723 /// true if we are looking at `const ID`, false for things like `const fn` etc
5724 fn is_const_item(&mut self) -> bool {
5725 self.token.is_keyword(keywords::Const) &&
5726 !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
5727 !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
5730 /// parses all the "front matter" for a `fn` declaration, up to
5731 /// and including the `fn` keyword:
5735 /// - `const unsafe fn`
5738 fn parse_fn_front_matter(&mut self)
5746 let is_const_fn = self.eat_keyword(keywords::Const);
5747 let const_span = self.prev_span;
5748 let unsafety = self.parse_unsafety();
5749 let asyncness = self.parse_asyncness();
5750 let (constness, unsafety, abi) = if is_const_fn {
5751 (respan(const_span, Constness::Const), unsafety, Abi::Rust)
5753 let abi = if self.eat_keyword(keywords::Extern) {
5754 self.parse_opt_abi()?.unwrap_or(Abi::C)
5758 (respan(self.prev_span, Constness::NotConst), unsafety, abi)
5760 self.expect_keyword(keywords::Fn)?;
5761 Ok((constness, unsafety, asyncness, abi))
5764 /// Parse an impl item.
5765 pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
5766 maybe_whole!(self, NtImplItem, |x| x);
5767 let attrs = self.parse_outer_attributes()?;
5768 let (mut item, tokens) = self.collect_tokens(|this| {
5769 this.parse_impl_item_(at_end, attrs)
5772 // See `parse_item` for why this clause is here.
5773 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
5774 item.tokens = Some(tokens);
5779 fn parse_impl_item_(&mut self,
5781 mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> {
5783 let vis = self.parse_visibility(false)?;
5784 let defaultness = self.parse_defaultness();
5785 let (name, node, generics) = if let Some(type_) = self.eat_type() {
5786 let (name, alias, generics) = type_?;
5787 let kind = match alias {
5788 AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ),
5789 AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds),
5791 (name, kind, generics)
5792 } else if self.is_const_item() {
5793 // This parses the grammar:
5794 // ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
5795 self.expect_keyword(keywords::Const)?;
5796 let name = self.parse_ident()?;
5797 self.expect(&token::Colon)?;
5798 let typ = self.parse_ty()?;
5799 self.expect(&token::Eq)?;
5800 let expr = self.parse_expr()?;
5801 self.expect(&token::Semi)?;
5802 (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default())
5804 let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?;
5805 attrs.extend(inner_attrs);
5806 (name, node, generics)
5810 id: ast::DUMMY_NODE_ID,
5811 span: lo.to(self.prev_span),
5822 fn complain_if_pub_macro(&mut self, vis: &VisibilityKind, sp: Span) {
5824 VisibilityKind::Inherited => {}
5826 let is_macro_rules: bool = match self.token {
5827 token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"),
5830 let mut err = if is_macro_rules {
5831 let mut err = self.diagnostic()
5832 .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
5833 err.span_suggestion_with_applicability(
5835 "try exporting the macro",
5836 "#[macro_export]".to_owned(),
5837 Applicability::MaybeIncorrect // speculative
5841 let mut err = self.diagnostic()
5842 .struct_span_err(sp, "can't qualify macro invocation with `pub`");
5843 err.help("try adjusting the macro to put `pub` inside the invocation");
5851 fn missing_assoc_item_kind_err(&mut self, item_type: &str, prev_span: Span)
5852 -> DiagnosticBuilder<'a>
5854 let expected_kinds = if item_type == "extern" {
5855 "missing `fn`, `type`, or `static`"
5857 "missing `fn`, `type`, or `const`"
5860 // Given this code `path(`, it seems like this is not
5861 // setting the visibility of a macro invocation, but rather
5862 // a mistyped method declaration.
5863 // Create a diagnostic pointing out that `fn` is missing.
5865 // x | pub path(&self) {
5866 // | ^ missing `fn`, `type`, or `const`
5868 // ^^ `sp` below will point to this
5869 let sp = prev_span.between(self.prev_span);
5870 let mut err = self.diagnostic().struct_span_err(
5872 &format!("{} for {}-item declaration",
5873 expected_kinds, item_type));
5874 err.span_label(sp, expected_kinds);
5878 /// Parse a method or a macro invocation in a trait impl.
5879 fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
5880 -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics,
5881 ast::ImplItemKind)> {
5882 // code copied from parse_macro_use_or_failure... abstraction!
5883 if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
5885 Ok((keywords::Invalid.ident(), vec![], ast::Generics::default(),
5886 ast::ImplItemKind::Macro(mac)))
5888 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
5889 let ident = self.parse_ident()?;
5890 let mut generics = self.parse_generics()?;
5891 let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
5892 generics.where_clause = self.parse_where_clause()?;
5894 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5895 let header = ast::FnHeader { abi, unsafety, constness, asyncness };
5896 Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
5897 ast::MethodSig { header, decl },
5903 /// Parse `trait Foo { ... }` or `trait Foo = Bar;`
5904 fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5905 let ident = self.parse_ident()?;
5906 let mut tps = self.parse_generics()?;
5908 // Parse optional colon and supertrait bounds.
5909 let bounds = if self.eat(&token::Colon) {
5910 self.parse_generic_bounds()?
5915 if self.eat(&token::Eq) {
5916 // it's a trait alias
5917 let bounds = self.parse_generic_bounds()?;
5918 tps.where_clause = self.parse_where_clause()?;
5919 self.expect(&token::Semi)?;
5920 if unsafety != Unsafety::Normal {
5921 self.span_err(self.prev_span, "trait aliases cannot be unsafe");
5923 Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
5925 // it's a normal trait
5926 tps.where_clause = self.parse_where_clause()?;
5927 self.expect(&token::OpenDelim(token::Brace))?;
5928 let mut trait_items = vec![];
5929 while !self.eat(&token::CloseDelim(token::Brace)) {
5930 let mut at_end = false;
5931 match self.parse_trait_item(&mut at_end) {
5932 Ok(item) => trait_items.push(item),
5936 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5941 Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
5945 fn choose_generics_over_qpath(&self) -> bool {
5946 // There's an ambiguity between generic parameters and qualified paths in impls.
5947 // If we see `<` it may start both, so we have to inspect some following tokens.
5948 // The following combinations can only start generics,
5949 // but not qualified paths (with one exception):
5950 // `<` `>` - empty generic parameters
5951 // `<` `#` - generic parameters with attributes
5952 // `<` (LIFETIME|IDENT) `>` - single generic parameter
5953 // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
5954 // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
5955 // `<` (LIFETIME|IDENT) `=` - generic parameter with a default
5956 // The only truly ambiguous case is
5957 // `<` IDENT `>` `::` IDENT ...
5958 // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
5959 // because this is what almost always expected in practice, qualified paths in impls
5960 // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
5961 self.token == token::Lt &&
5962 (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
5963 self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
5964 self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
5965 t == &token::Colon || t == &token::Eq))
5968 fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
5969 self.expect(&token::OpenDelim(token::Brace))?;
5970 let attrs = self.parse_inner_attributes()?;
5972 let mut impl_items = Vec::new();
5973 while !self.eat(&token::CloseDelim(token::Brace)) {
5974 let mut at_end = false;
5975 match self.parse_impl_item(&mut at_end) {
5976 Ok(impl_item) => impl_items.push(impl_item),
5980 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5985 Ok((impl_items, attrs))
5988 /// Parses an implementation item, `impl` keyword is already parsed.
5989 /// impl<'a, T> TYPE { /* impl items */ }
5990 /// impl<'a, T> TRAIT for TYPE { /* impl items */ }
5991 /// impl<'a, T> !TRAIT for TYPE { /* impl items */ }
5992 /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
5993 /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
5994 /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
5995 fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
5996 -> PResult<'a, ItemInfo> {
5997 // First, parse generic parameters if necessary.
5998 let mut generics = if self.choose_generics_over_qpath() {
5999 self.parse_generics()?
6001 ast::Generics::default()
6004 // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
6005 let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
6007 ast::ImplPolarity::Negative
6009 ast::ImplPolarity::Positive
6012 // Parse both types and traits as a type, then reinterpret if necessary.
6013 let ty_first = self.parse_ty()?;
6015 // If `for` is missing we try to recover.
6016 let has_for = self.eat_keyword(keywords::For);
6017 let missing_for_span = self.prev_span.between(self.span);
6019 let ty_second = if self.token == token::DotDot {
6020 // We need to report this error after `cfg` expansion for compatibility reasons
6021 self.bump(); // `..`, do not add it to expected tokens
6022 Some(P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID }))
6023 } else if has_for || self.token.can_begin_type() {
6024 Some(self.parse_ty()?)
6029 generics.where_clause = self.parse_where_clause()?;
6031 let (impl_items, attrs) = self.parse_impl_body()?;
6033 let item_kind = match ty_second {
6034 Some(ty_second) => {
6035 // impl Trait for Type
6037 self.span_err(missing_for_span, "missing `for` in a trait impl");
6040 let ty_first = ty_first.into_inner();
6041 let path = match ty_first.node {
6042 // This notably includes paths passed through `ty` macro fragments (#46438).
6043 TyKind::Path(None, path) => path,
6045 self.span_err(ty_first.span, "expected a trait, found type");
6046 ast::Path::from_ident(Ident::new(keywords::Invalid.name(), ty_first.span))
6049 let trait_ref = TraitRef { path, ref_id: ty_first.id };
6051 ItemKind::Impl(unsafety, polarity, defaultness,
6052 generics, Some(trait_ref), ty_second, impl_items)
6056 ItemKind::Impl(unsafety, polarity, defaultness,
6057 generics, None, ty_first, impl_items)
6061 Ok((keywords::Invalid.ident(), item_kind, Some(attrs)))
6064 fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
6065 if self.eat_keyword(keywords::For) {
6067 let params = self.parse_generic_params()?;
6069 // We rely on AST validation to rule out invalid cases: There must not be type
6070 // parameters, and the lifetime parameters must not have bounds.
6077 /// Parse struct Foo { ... }
6078 fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
6079 let class_name = self.parse_ident()?;
6081 let mut generics = self.parse_generics()?;
6083 // There is a special case worth noting here, as reported in issue #17904.
6084 // If we are parsing a tuple struct it is the case that the where clause
6085 // should follow the field list. Like so:
6087 // struct Foo<T>(T) where T: Copy;
6089 // If we are parsing a normal record-style struct it is the case
6090 // that the where clause comes before the body, and after the generics.
6091 // So if we look ahead and see a brace or a where-clause we begin
6092 // parsing a record style struct.
6094 // Otherwise if we look ahead and see a paren we parse a tuple-style
6097 let vdata = if self.token.is_keyword(keywords::Where) {
6098 generics.where_clause = self.parse_where_clause()?;
6099 if self.eat(&token::Semi) {
6100 // If we see a: `struct Foo<T> where T: Copy;` style decl.
6101 VariantData::Unit(ast::DUMMY_NODE_ID)
6103 // If we see: `struct Foo<T> where T: Copy { ... }`
6104 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6106 // No `where` so: `struct Foo<T>;`
6107 } else if self.eat(&token::Semi) {
6108 VariantData::Unit(ast::DUMMY_NODE_ID)
6109 // Record-style struct definition
6110 } else if self.token == token::OpenDelim(token::Brace) {
6111 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6112 // Tuple-style struct definition with optional where-clause.
6113 } else if self.token == token::OpenDelim(token::Paren) {
6114 let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID);
6115 generics.where_clause = self.parse_where_clause()?;
6116 self.expect(&token::Semi)?;
6119 let token_str = self.this_token_descr();
6120 let mut err = self.fatal(&format!(
6121 "expected `where`, `{{`, `(`, or `;` after struct name, found {}",
6124 err.span_label(self.span, "expected `where`, `{`, `(`, or `;` after struct name");
6128 Ok((class_name, ItemKind::Struct(vdata, generics), None))
6131 /// Parse union Foo { ... }
6132 fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
6133 let class_name = self.parse_ident()?;
6135 let mut generics = self.parse_generics()?;
6137 let vdata = if self.token.is_keyword(keywords::Where) {
6138 generics.where_clause = self.parse_where_clause()?;
6139 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6140 } else if self.token == token::OpenDelim(token::Brace) {
6141 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6143 let token_str = self.this_token_descr();
6144 let mut err = self.fatal(&format!(
6145 "expected `where` or `{{` after union name, found {}", token_str));
6146 err.span_label(self.span, "expected `where` or `{` after union name");
6150 Ok((class_name, ItemKind::Union(vdata, generics), None))
6153 fn consume_block(&mut self, delim: token::DelimToken) {
6154 let mut brace_depth = 0;
6156 if self.eat(&token::OpenDelim(delim)) {
6158 } else if self.eat(&token::CloseDelim(delim)) {
6159 if brace_depth == 0 {
6165 } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
6173 fn parse_record_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6174 let mut fields = Vec::new();
6175 if self.eat(&token::OpenDelim(token::Brace)) {
6176 while self.token != token::CloseDelim(token::Brace) {
6177 let field = self.parse_struct_decl_field().map_err(|e| {
6178 self.recover_stmt();
6182 Ok(field) => fields.push(field),
6188 self.eat(&token::CloseDelim(token::Brace));
6190 let token_str = self.this_token_descr();
6191 let mut err = self.fatal(&format!(
6192 "expected `where`, or `{{` after struct name, found {}", token_str));
6193 err.span_label(self.span, "expected `where`, or `{` after struct name");
6200 fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6201 // This is the case where we find `struct Foo<T>(T) where T: Copy;`
6202 // Unit like structs are handled in parse_item_struct function
6203 let fields = self.parse_unspanned_seq(
6204 &token::OpenDelim(token::Paren),
6205 &token::CloseDelim(token::Paren),
6206 SeqSep::trailing_allowed(token::Comma),
6208 let attrs = p.parse_outer_attributes()?;
6210 let vis = p.parse_visibility(true)?;
6211 let ty = p.parse_ty()?;
6213 span: lo.to(ty.span),
6216 id: ast::DUMMY_NODE_ID,
6225 /// Parse a structure field declaration
6226 fn parse_single_struct_field(&mut self,
6229 attrs: Vec<Attribute> )
6230 -> PResult<'a, StructField> {
6231 let mut seen_comma: bool = false;
6232 let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
6233 if self.token == token::Comma {
6240 token::CloseDelim(token::Brace) => {}
6241 token::DocComment(_) => {
6242 let previous_span = self.prev_span;
6243 let mut err = self.span_fatal_err(self.span, Error::UselessDocComment);
6244 self.bump(); // consume the doc comment
6245 let comma_after_doc_seen = self.eat(&token::Comma);
6246 // `seen_comma` is always false, because we are inside doc block
6247 // condition is here to make code more readable
6248 if seen_comma == false && comma_after_doc_seen == true {
6251 if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
6254 if seen_comma == false {
6255 let sp = self.sess.source_map().next_point(previous_span);
6256 err.span_suggestion_with_applicability(
6258 "missing comma here",
6260 Applicability::MachineApplicable
6267 let sp = self.sess.source_map().next_point(self.prev_span);
6268 let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}",
6269 self.this_token_descr()));
6270 if self.token.is_ident() {
6271 // This is likely another field; emit the diagnostic and keep going
6272 err.span_suggestion_with_applicability(
6274 "try adding a comma",
6276 Applicability::MachineApplicable,
6287 /// Parse an element of a struct definition
6288 fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
6289 let attrs = self.parse_outer_attributes()?;
6291 let vis = self.parse_visibility(false)?;
6292 self.parse_single_struct_field(lo, vis, attrs)
6295 /// Parse `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
6296 /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
6297 /// If the following element can't be a tuple (i.e., it's a function definition,
6298 /// it's not a tuple struct field) and the contents within the parens
6299 /// isn't valid, emit a proper diagnostic.
6300 pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
6301 maybe_whole!(self, NtVis, |x| x);
6303 self.expected_tokens.push(TokenType::Keyword(keywords::Crate));
6304 if self.is_crate_vis() {
6305 self.bump(); // `crate`
6306 return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
6309 if !self.eat_keyword(keywords::Pub) {
6310 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
6311 // keyword to grab a span from for inherited visibility; an empty span at the
6312 // beginning of the current token would seem to be the "Schelling span".
6313 return Ok(respan(self.span.shrink_to_lo(), VisibilityKind::Inherited))
6315 let lo = self.prev_span;
6317 if self.check(&token::OpenDelim(token::Paren)) {
6318 // We don't `self.bump()` the `(` yet because this might be a struct definition where
6319 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
6320 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
6321 // by the following tokens.
6322 if self.look_ahead(1, |t| t.is_keyword(keywords::Crate)) {
6325 self.bump(); // `crate`
6326 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6328 lo.to(self.prev_span),
6329 VisibilityKind::Crate(CrateSugar::PubCrate),
6332 } else if self.look_ahead(1, |t| t.is_keyword(keywords::In)) {
6335 self.bump(); // `in`
6336 let path = self.parse_path(PathStyle::Mod)?; // `path`
6337 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6338 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6340 id: ast::DUMMY_NODE_ID,
6343 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
6344 self.look_ahead(1, |t| t.is_keyword(keywords::Super) ||
6345 t.is_keyword(keywords::SelfLower))
6347 // `pub(self)` or `pub(super)`
6349 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
6350 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6351 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6353 id: ast::DUMMY_NODE_ID,
6356 } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct
6357 // `pub(something) fn ...` or `struct X { pub(something) y: Z }`
6359 let msg = "incorrect visibility restriction";
6360 let suggestion = r##"some possible visibility restrictions are:
6361 `pub(crate)`: visible only on the current crate
6362 `pub(super)`: visible only in the current module's parent
6363 `pub(in path::to::module)`: visible only on the specified path"##;
6364 let path = self.parse_path(PathStyle::Mod)?;
6365 let sp = self.prev_span;
6366 let help_msg = format!("make this visible only to module `{}` with `in`", path);
6367 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6368 let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg);
6369 err.help(suggestion);
6370 err.span_suggestion_with_applicability(
6371 sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable
6373 err.emit(); // emit diagnostic, but continue with public visibility
6377 Ok(respan(lo, VisibilityKind::Public))
6380 /// Parse defaultness: `default` or nothing.
6381 fn parse_defaultness(&mut self) -> Defaultness {
6382 // `pub` is included for better error messages
6383 if self.check_keyword(keywords::Default) &&
6384 self.look_ahead(1, |t| t.is_keyword(keywords::Impl) ||
6385 t.is_keyword(keywords::Const) ||
6386 t.is_keyword(keywords::Fn) ||
6387 t.is_keyword(keywords::Unsafe) ||
6388 t.is_keyword(keywords::Extern) ||
6389 t.is_keyword(keywords::Type) ||
6390 t.is_keyword(keywords::Pub)) {
6391 self.bump(); // `default`
6392 Defaultness::Default
6398 /// Given a termination token, parse all of the items in a module
6399 fn parse_mod_items(&mut self, term: &token::Token, inner_lo: Span) -> PResult<'a, Mod> {
6400 let mut items = vec![];
6401 while let Some(item) = self.parse_item()? {
6405 if !self.eat(term) {
6406 let token_str = self.this_token_descr();
6407 let mut err = self.fatal(&format!("expected item, found {}", token_str));
6408 if self.token == token::Semi {
6409 let msg = "consider removing this semicolon";
6410 err.span_suggestion_short_with_applicability(
6411 self.span, msg, String::new(), Applicability::MachineApplicable
6413 if !items.is_empty() { // Issue #51603
6414 let previous_item = &items[items.len()-1];
6415 let previous_item_kind_name = match previous_item.node {
6416 // say "braced struct" because tuple-structs and
6417 // braceless-empty-struct declarations do take a semicolon
6418 ItemKind::Struct(..) => Some("braced struct"),
6419 ItemKind::Enum(..) => Some("enum"),
6420 ItemKind::Trait(..) => Some("trait"),
6421 ItemKind::Union(..) => Some("union"),
6424 if let Some(name) = previous_item_kind_name {
6425 err.help(&format!("{} declarations are not followed by a semicolon",
6430 err.span_label(self.span, "expected item");
6435 let hi = if self.span.is_dummy() {
6442 inner: inner_lo.to(hi),
6448 fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
6449 let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?;
6450 self.expect(&token::Colon)?;
6451 let ty = self.parse_ty()?;
6452 self.expect(&token::Eq)?;
6453 let e = self.parse_expr()?;
6454 self.expect(&token::Semi)?;
6455 let item = match m {
6456 Some(m) => ItemKind::Static(ty, m, e),
6457 None => ItemKind::Const(ty, e),
6459 Ok((id, item, None))
6462 /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
6463 fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
6464 let (in_cfg, outer_attrs) = {
6465 let mut strip_unconfigured = ::config::StripUnconfigured {
6467 features: None, // don't perform gated feature checking
6469 let outer_attrs = strip_unconfigured.process_cfg_attrs(outer_attrs.to_owned());
6470 (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), outer_attrs)
6473 let id_span = self.span;
6474 let id = self.parse_ident()?;
6475 if self.eat(&token::Semi) {
6476 if in_cfg && self.recurse_into_file_modules {
6477 // This mod is in an external file. Let's go get it!
6478 let ModulePathSuccess { path, directory_ownership, warn } =
6479 self.submod_path(id, &outer_attrs, id_span)?;
6480 let (module, mut attrs) =
6481 self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
6482 // Record that we fetched the mod from an external file
6484 let attr = Attribute {
6485 id: attr::mk_attr_id(),
6486 style: ast::AttrStyle::Outer,
6487 path: ast::Path::from_ident(Ident::from_str("warn_directory_ownership")),
6488 tokens: TokenStream::empty(),
6489 is_sugared_doc: false,
6490 span: syntax_pos::DUMMY_SP,
6492 attr::mark_known(&attr);
6495 Ok((id, ItemKind::Mod(module), Some(attrs)))
6497 let placeholder = ast::Mod {
6498 inner: syntax_pos::DUMMY_SP,
6502 Ok((id, ItemKind::Mod(placeholder), None))
6505 let old_directory = self.directory.clone();
6506 self.push_directory(id, &outer_attrs);
6508 self.expect(&token::OpenDelim(token::Brace))?;
6509 let mod_inner_lo = self.span;
6510 let attrs = self.parse_inner_attributes()?;
6511 let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
6513 self.directory = old_directory;
6514 Ok((id, ItemKind::Mod(module), Some(attrs)))
6518 fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
6519 if let Some(path) = attr::first_attr_value_str_by_name(attrs, "path") {
6520 self.directory.path.to_mut().push(&path.as_str());
6521 self.directory.ownership = DirectoryOwnership::Owned { relative: None };
6523 // We have to push on the current module name in the case of relative
6524 // paths in order to ensure that any additional module paths from inline
6525 // `mod x { ... }` come after the relative extension.
6527 // For example, a `mod z { ... }` inside `x/y.rs` should set the current
6528 // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
6529 if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
6530 if let Some(ident) = relative.take() { // remove the relative offset
6531 self.directory.path.to_mut().push(ident.as_str());
6534 self.directory.path.to_mut().push(&id.as_str());
6538 pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
6539 if let Some(s) = attr::first_attr_value_str_by_name(attrs, "path") {
6542 // On windows, the base path might have the form
6543 // `\\?\foo\bar` in which case it does not tolerate
6544 // mixed `/` and `\` separators, so canonicalize
6547 let s = s.replace("/", "\\");
6548 Some(dir_path.join(s))
6554 /// Returns either a path to a module, or .
6555 pub fn default_submod_path(
6557 relative: Option<ast::Ident>,
6559 source_map: &SourceMap) -> ModulePath
6561 // If we're in a foo.rs file instead of a mod.rs file,
6562 // we need to look for submodules in
6563 // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
6564 // `./<id>.rs` and `./<id>/mod.rs`.
6565 let relative_prefix_string;
6566 let relative_prefix = if let Some(ident) = relative {
6567 relative_prefix_string = format!("{}{}", ident.as_str(), path::MAIN_SEPARATOR);
6568 &relative_prefix_string
6573 let mod_name = id.to_string();
6574 let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
6575 let secondary_path_str = format!("{}{}{}mod.rs",
6576 relative_prefix, mod_name, path::MAIN_SEPARATOR);
6577 let default_path = dir_path.join(&default_path_str);
6578 let secondary_path = dir_path.join(&secondary_path_str);
6579 let default_exists = source_map.file_exists(&default_path);
6580 let secondary_exists = source_map.file_exists(&secondary_path);
6582 let result = match (default_exists, secondary_exists) {
6583 (true, false) => Ok(ModulePathSuccess {
6585 directory_ownership: DirectoryOwnership::Owned {
6590 (false, true) => Ok(ModulePathSuccess {
6591 path: secondary_path,
6592 directory_ownership: DirectoryOwnership::Owned {
6597 (false, false) => Err(Error::FileNotFoundForModule {
6598 mod_name: mod_name.clone(),
6599 default_path: default_path_str,
6600 secondary_path: secondary_path_str,
6601 dir_path: dir_path.display().to_string(),
6603 (true, true) => Err(Error::DuplicatePaths {
6604 mod_name: mod_name.clone(),
6605 default_path: default_path_str,
6606 secondary_path: secondary_path_str,
6612 path_exists: default_exists || secondary_exists,
6617 fn submod_path(&mut self,
6619 outer_attrs: &[Attribute],
6621 -> PResult<'a, ModulePathSuccess> {
6622 if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
6623 return Ok(ModulePathSuccess {
6624 directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
6625 // All `#[path]` files are treated as though they are a `mod.rs` file.
6626 // This means that `mod foo;` declarations inside `#[path]`-included
6627 // files are siblings,
6629 // Note that this will produce weirdness when a file named `foo.rs` is
6630 // `#[path]` included and contains a `mod foo;` declaration.
6631 // If you encounter this, it's your own darn fault :P
6632 Some(_) => DirectoryOwnership::Owned { relative: None },
6633 _ => DirectoryOwnership::UnownedViaMod(true),
6640 let relative = match self.directory.ownership {
6641 DirectoryOwnership::Owned { relative } => relative,
6642 DirectoryOwnership::UnownedViaBlock |
6643 DirectoryOwnership::UnownedViaMod(_) => None,
6645 let paths = Parser::default_submod_path(
6646 id, relative, &self.directory.path, self.sess.source_map());
6648 match self.directory.ownership {
6649 DirectoryOwnership::Owned { .. } => {
6650 paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
6652 DirectoryOwnership::UnownedViaBlock => {
6654 "Cannot declare a non-inline module inside a block \
6655 unless it has a path attribute";
6656 let mut err = self.diagnostic().struct_span_err(id_sp, msg);
6657 if paths.path_exists {
6658 let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
6660 err.span_note(id_sp, &msg);
6664 DirectoryOwnership::UnownedViaMod(warn) => {
6666 if let Ok(result) = paths.result {
6667 return Ok(ModulePathSuccess { warn: true, ..result });
6670 let mut err = self.diagnostic().struct_span_err(id_sp,
6671 "cannot declare a new module at this location");
6672 if !id_sp.is_dummy() {
6673 let src_path = self.sess.source_map().span_to_filename(id_sp);
6674 if let FileName::Real(src_path) = src_path {
6675 if let Some(stem) = src_path.file_stem() {
6676 let mut dest_path = src_path.clone();
6677 dest_path.set_file_name(stem);
6678 dest_path.push("mod.rs");
6679 err.span_note(id_sp,
6680 &format!("maybe move this module `{}` to its own \
6681 directory via `{}`", src_path.display(),
6682 dest_path.display()));
6686 if paths.path_exists {
6687 err.span_note(id_sp,
6688 &format!("... or maybe `use` the module `{}` instead \
6689 of possibly redeclaring it",
6697 /// Read a module from a source file.
6698 fn eval_src_mod(&mut self,
6700 directory_ownership: DirectoryOwnership,
6703 -> PResult<'a, (ast::Mod, Vec<Attribute> )> {
6704 let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
6705 if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
6706 let mut err = String::from("circular modules: ");
6707 let len = included_mod_stack.len();
6708 for p in &included_mod_stack[i.. len] {
6709 err.push_str(&p.to_string_lossy());
6710 err.push_str(" -> ");
6712 err.push_str(&path.to_string_lossy());
6713 return Err(self.span_fatal(id_sp, &err[..]));
6715 included_mod_stack.push(path.clone());
6716 drop(included_mod_stack);
6719 new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
6720 p0.cfg_mods = self.cfg_mods;
6721 let mod_inner_lo = p0.span;
6722 let mod_attrs = p0.parse_inner_attributes()?;
6723 let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
6725 self.sess.included_mod_stack.borrow_mut().pop();
6729 /// Parse a function declaration from a foreign module
6730 fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6731 -> PResult<'a, ForeignItem> {
6732 self.expect_keyword(keywords::Fn)?;
6734 let (ident, mut generics) = self.parse_fn_header()?;
6735 let decl = self.parse_fn_decl(true)?;
6736 generics.where_clause = self.parse_where_clause()?;
6738 self.expect(&token::Semi)?;
6739 Ok(ast::ForeignItem {
6742 node: ForeignItemKind::Fn(decl, generics),
6743 id: ast::DUMMY_NODE_ID,
6749 /// Parse a static item from a foreign module.
6750 /// Assumes that the `static` keyword is already parsed.
6751 fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6752 -> PResult<'a, ForeignItem> {
6753 let mutbl = self.eat_keyword(keywords::Mut);
6754 let ident = self.parse_ident()?;
6755 self.expect(&token::Colon)?;
6756 let ty = self.parse_ty()?;
6758 self.expect(&token::Semi)?;
6762 node: ForeignItemKind::Static(ty, mutbl),
6763 id: ast::DUMMY_NODE_ID,
6769 /// Parse a type from a foreign module
6770 fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6771 -> PResult<'a, ForeignItem> {
6772 self.expect_keyword(keywords::Type)?;
6774 let ident = self.parse_ident()?;
6776 self.expect(&token::Semi)?;
6777 Ok(ast::ForeignItem {
6780 node: ForeignItemKind::Ty,
6781 id: ast::DUMMY_NODE_ID,
6787 fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
6788 let error_msg = "crate name using dashes are not valid in `extern crate` statements";
6789 let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
6791 let mut ident = if self.token.is_keyword(keywords::SelfLower) {
6792 self.parse_path_segment_ident()
6796 let mut idents = vec![];
6797 let mut replacement = vec![];
6798 let mut fixed_crate_name = false;
6799 // Accept `extern crate name-like-this` for better diagnostics
6800 let dash = token::Token::BinOp(token::BinOpToken::Minus);
6801 if self.token == dash { // Do not include `-` as part of the expected tokens list
6802 while self.eat(&dash) {
6803 fixed_crate_name = true;
6804 replacement.push((self.prev_span, "_".to_string()));
6805 idents.push(self.parse_ident()?);
6808 if fixed_crate_name {
6809 let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
6810 let mut fixed_name = format!("{}", ident.name);
6811 for part in idents {
6812 fixed_name.push_str(&format!("_{}", part.name));
6814 ident = Ident::from_str(&fixed_name).with_span_pos(fixed_name_sp);
6816 let mut err = self.struct_span_err(fixed_name_sp, error_msg);
6817 err.span_label(fixed_name_sp, "dash-separated idents are not valid");
6818 err.multipart_suggestion(suggestion_msg, replacement);
6824 /// Parse extern crate links
6828 /// extern crate foo;
6829 /// extern crate bar as foo;
6830 fn parse_item_extern_crate(&mut self,
6832 visibility: Visibility,
6833 attrs: Vec<Attribute>)
6834 -> PResult<'a, P<Item>> {
6835 // Accept `extern crate name-like-this` for better diagnostics
6836 let orig_name = self.parse_crate_name_with_dashes()?;
6837 let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
6838 (rename, Some(orig_name.name))
6842 self.expect(&token::Semi)?;
6844 let span = lo.to(self.prev_span);
6845 Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
6848 /// Parse `extern` for foreign ABIs
6851 /// `extern` is expected to have been
6852 /// consumed before calling this method
6858 fn parse_item_foreign_mod(&mut self,
6860 opt_abi: Option<Abi>,
6861 visibility: Visibility,
6862 mut attrs: Vec<Attribute>)
6863 -> PResult<'a, P<Item>> {
6864 self.expect(&token::OpenDelim(token::Brace))?;
6866 let abi = opt_abi.unwrap_or(Abi::C);
6868 attrs.extend(self.parse_inner_attributes()?);
6870 let mut foreign_items = vec![];
6871 while !self.eat(&token::CloseDelim(token::Brace)) {
6872 foreign_items.push(self.parse_foreign_item()?);
6875 let prev_span = self.prev_span;
6876 let m = ast::ForeignMod {
6878 items: foreign_items
6880 let invalid = keywords::Invalid.ident();
6881 Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
6884 /// Parse `type Foo = Bar;`
6886 /// `existential type Foo: Bar;`
6888 /// `return None` without modifying the parser state
6889 fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
6890 // This parses the grammar:
6891 // Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
6892 if self.check_keyword(keywords::Type) ||
6893 self.check_keyword(keywords::Existential) &&
6894 self.look_ahead(1, |t| t.is_keyword(keywords::Type)) {
6895 let existential = self.eat_keyword(keywords::Existential);
6896 assert!(self.eat_keyword(keywords::Type));
6897 Some(self.parse_existential_or_alias(existential))
6903 /// Parse type alias or existential type
6904 fn parse_existential_or_alias(
6907 ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
6908 let ident = self.parse_ident()?;
6909 let mut tps = self.parse_generics()?;
6910 tps.where_clause = self.parse_where_clause()?;
6911 let alias = if existential {
6912 self.expect(&token::Colon)?;
6913 let bounds = self.parse_generic_bounds()?;
6914 AliasKind::Existential(bounds)
6916 self.expect(&token::Eq)?;
6917 let ty = self.parse_ty()?;
6920 self.expect(&token::Semi)?;
6921 Ok((ident, alias, tps))
6924 /// Parse the part of an "enum" decl following the '{'
6925 fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
6926 let mut variants = Vec::new();
6927 let mut all_nullary = true;
6928 let mut any_disr = None;
6929 while self.token != token::CloseDelim(token::Brace) {
6930 let variant_attrs = self.parse_outer_attributes()?;
6931 let vlo = self.span;
6934 let mut disr_expr = None;
6935 let ident = self.parse_ident()?;
6936 if self.check(&token::OpenDelim(token::Brace)) {
6937 // Parse a struct variant.
6938 all_nullary = false;
6939 struct_def = VariantData::Struct(self.parse_record_struct_body()?,
6940 ast::DUMMY_NODE_ID);
6941 } else if self.check(&token::OpenDelim(token::Paren)) {
6942 all_nullary = false;
6943 struct_def = VariantData::Tuple(self.parse_tuple_struct_body()?,
6944 ast::DUMMY_NODE_ID);
6945 } else if self.eat(&token::Eq) {
6946 disr_expr = Some(AnonConst {
6947 id: ast::DUMMY_NODE_ID,
6948 value: self.parse_expr()?,
6950 any_disr = disr_expr.as_ref().map(|c| c.value.span);
6951 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6953 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6956 let vr = ast::Variant_ {
6958 attrs: variant_attrs,
6962 variants.push(respan(vlo.to(self.prev_span), vr));
6964 if !self.eat(&token::Comma) { break; }
6966 self.expect(&token::CloseDelim(token::Brace))?;
6968 Some(disr_span) if !all_nullary =>
6969 self.span_err(disr_span,
6970 "discriminator values can only be used with a field-less enum"),
6974 Ok(ast::EnumDef { variants })
6977 /// Parse an "enum" declaration
6978 fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
6979 let id = self.parse_ident()?;
6980 let mut generics = self.parse_generics()?;
6981 generics.where_clause = self.parse_where_clause()?;
6982 self.expect(&token::OpenDelim(token::Brace))?;
6984 let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
6985 self.recover_stmt();
6986 self.eat(&token::CloseDelim(token::Brace));
6989 Ok((id, ItemKind::Enum(enum_definition, generics), None))
6992 /// Parses a string as an ABI spec on an extern type or module. Consumes
6993 /// the `extern` keyword, if one is found.
6994 fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
6996 token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
6998 self.expect_no_suffix(sp, "ABI spec", suf);
7000 match abi::lookup(&s.as_str()) {
7001 Some(abi) => Ok(Some(abi)),
7003 let prev_span = self.prev_span;
7004 let mut err = struct_span_err!(
7005 self.sess.span_diagnostic,
7008 "invalid ABI: found `{}`",
7010 err.span_label(prev_span, "invalid ABI");
7011 err.help(&format!("valid ABIs: {}", abi::all_names().join(", ")));
7022 fn is_static_global(&mut self) -> bool {
7023 if self.check_keyword(keywords::Static) {
7024 // Check if this could be a closure
7025 !self.look_ahead(1, |token| {
7026 if token.is_keyword(keywords::Move) {
7030 token::BinOp(token::Or) | token::OrOr => true,
7041 attrs: Vec<Attribute>,
7042 macros_allowed: bool,
7043 attributes_allowed: bool,
7044 ) -> PResult<'a, Option<P<Item>>> {
7045 let (ret, tokens) = self.collect_tokens(|this| {
7046 this.parse_item_implementation(attrs, macros_allowed, attributes_allowed)
7049 // Once we've parsed an item and recorded the tokens we got while
7050 // parsing we may want to store `tokens` into the item we're about to
7051 // return. Note, though, that we specifically didn't capture tokens
7052 // related to outer attributes. The `tokens` field here may later be
7053 // used with procedural macros to convert this item back into a token
7054 // stream, but during expansion we may be removing attributes as we go
7057 // If we've got inner attributes then the `tokens` we've got above holds
7058 // these inner attributes. If an inner attribute is expanded we won't
7059 // actually remove it from the token stream, so we'll just keep yielding
7060 // it (bad!). To work around this case for now we just avoid recording
7061 // `tokens` if we detect any inner attributes. This should help keep
7062 // expansion correct, but we should fix this bug one day!
7065 if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
7066 i.tokens = Some(tokens);
7073 /// Parse one of the items allowed by the flags.
7074 fn parse_item_implementation(
7076 attrs: Vec<Attribute>,
7077 macros_allowed: bool,
7078 attributes_allowed: bool,
7079 ) -> PResult<'a, Option<P<Item>>> {
7080 maybe_whole!(self, NtItem, |item| {
7081 let mut item = item.into_inner();
7082 let mut attrs = attrs;
7083 mem::swap(&mut item.attrs, &mut attrs);
7084 item.attrs.extend(attrs);
7090 let visibility = self.parse_visibility(false)?;
7092 if self.eat_keyword(keywords::Use) {
7094 let item_ = ItemKind::Use(P(self.parse_use_tree()?));
7095 self.expect(&token::Semi)?;
7097 let span = lo.to(self.prev_span);
7098 let item = self.mk_item(span, keywords::Invalid.ident(), item_, visibility, attrs);
7099 return Ok(Some(item));
7102 if self.check_keyword(keywords::Extern) && self.is_extern_non_path() {
7103 self.bump(); // `extern`
7104 if self.eat_keyword(keywords::Crate) {
7105 return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
7108 let opt_abi = self.parse_opt_abi()?;
7110 if self.eat_keyword(keywords::Fn) {
7111 // EXTERN FUNCTION ITEM
7112 let fn_span = self.prev_span;
7113 let abi = opt_abi.unwrap_or(Abi::C);
7114 let (ident, item_, extra_attrs) =
7115 self.parse_item_fn(Unsafety::Normal,
7117 respan(fn_span, Constness::NotConst),
7119 let prev_span = self.prev_span;
7120 let item = self.mk_item(lo.to(prev_span),
7124 maybe_append(attrs, extra_attrs));
7125 return Ok(Some(item));
7126 } else if self.check(&token::OpenDelim(token::Brace)) {
7127 return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
7133 if self.is_static_global() {
7136 let m = if self.eat_keyword(keywords::Mut) {
7139 Mutability::Immutable
7141 let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
7142 let prev_span = self.prev_span;
7143 let item = self.mk_item(lo.to(prev_span),
7147 maybe_append(attrs, extra_attrs));
7148 return Ok(Some(item));
7150 if self.eat_keyword(keywords::Const) {
7151 let const_span = self.prev_span;
7152 if self.check_keyword(keywords::Fn)
7153 || (self.check_keyword(keywords::Unsafe)
7154 && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
7155 // CONST FUNCTION ITEM
7156 let unsafety = self.parse_unsafety();
7158 let (ident, item_, extra_attrs) =
7159 self.parse_item_fn(unsafety,
7161 respan(const_span, Constness::Const),
7163 let prev_span = self.prev_span;
7164 let item = self.mk_item(lo.to(prev_span),
7168 maybe_append(attrs, extra_attrs));
7169 return Ok(Some(item));
7173 if self.eat_keyword(keywords::Mut) {
7174 let prev_span = self.prev_span;
7175 self.diagnostic().struct_span_err(prev_span, "const globals cannot be mutable")
7176 .help("did you mean to declare a static?")
7179 let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
7180 let prev_span = self.prev_span;
7181 let item = self.mk_item(lo.to(prev_span),
7185 maybe_append(attrs, extra_attrs));
7186 return Ok(Some(item));
7189 // `unsafe async fn` or `async fn`
7191 self.check_keyword(keywords::Unsafe) &&
7192 self.look_ahead(1, |t| t.is_keyword(keywords::Async))
7194 self.check_keyword(keywords::Async) &&
7195 self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
7198 // ASYNC FUNCTION ITEM
7199 let unsafety = self.parse_unsafety();
7200 self.expect_keyword(keywords::Async)?;
7201 self.expect_keyword(keywords::Fn)?;
7202 let fn_span = self.prev_span;
7203 let (ident, item_, extra_attrs) =
7204 self.parse_item_fn(unsafety,
7206 closure_id: ast::DUMMY_NODE_ID,
7207 return_impl_trait_id: ast::DUMMY_NODE_ID,
7209 respan(fn_span, Constness::NotConst),
7211 let prev_span = self.prev_span;
7212 let item = self.mk_item(lo.to(prev_span),
7216 maybe_append(attrs, extra_attrs));
7217 return Ok(Some(item));
7219 if self.check_keyword(keywords::Unsafe) &&
7220 (self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) ||
7221 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)))
7223 // UNSAFE TRAIT ITEM
7224 self.bump(); // `unsafe`
7225 let is_auto = if self.eat_keyword(keywords::Trait) {
7228 self.expect_keyword(keywords::Auto)?;
7229 self.expect_keyword(keywords::Trait)?;
7232 let (ident, item_, extra_attrs) =
7233 self.parse_item_trait(is_auto, Unsafety::Unsafe)?;
7234 let prev_span = self.prev_span;
7235 let item = self.mk_item(lo.to(prev_span),
7239 maybe_append(attrs, extra_attrs));
7240 return Ok(Some(item));
7242 if self.check_keyword(keywords::Impl) ||
7243 self.check_keyword(keywords::Unsafe) &&
7244 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7245 self.check_keyword(keywords::Default) &&
7246 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7247 self.check_keyword(keywords::Default) &&
7248 self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) {
7250 let defaultness = self.parse_defaultness();
7251 let unsafety = self.parse_unsafety();
7252 self.expect_keyword(keywords::Impl)?;
7253 let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?;
7254 let span = lo.to(self.prev_span);
7255 return Ok(Some(self.mk_item(span, ident, item, visibility,
7256 maybe_append(attrs, extra_attrs))));
7258 if self.check_keyword(keywords::Fn) {
7261 let fn_span = self.prev_span;
7262 let (ident, item_, extra_attrs) =
7263 self.parse_item_fn(Unsafety::Normal,
7265 respan(fn_span, Constness::NotConst),
7267 let prev_span = self.prev_span;
7268 let item = self.mk_item(lo.to(prev_span),
7272 maybe_append(attrs, extra_attrs));
7273 return Ok(Some(item));
7275 if self.check_keyword(keywords::Unsafe)
7276 && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
7277 // UNSAFE FUNCTION ITEM
7278 self.bump(); // `unsafe`
7279 // `{` is also expected after `unsafe`, in case of error, include it in the diagnostic
7280 self.check(&token::OpenDelim(token::Brace));
7281 let abi = if self.eat_keyword(keywords::Extern) {
7282 self.parse_opt_abi()?.unwrap_or(Abi::C)
7286 self.expect_keyword(keywords::Fn)?;
7287 let fn_span = self.prev_span;
7288 let (ident, item_, extra_attrs) =
7289 self.parse_item_fn(Unsafety::Unsafe,
7291 respan(fn_span, Constness::NotConst),
7293 let prev_span = self.prev_span;
7294 let item = self.mk_item(lo.to(prev_span),
7298 maybe_append(attrs, extra_attrs));
7299 return Ok(Some(item));
7301 if self.eat_keyword(keywords::Mod) {
7303 let (ident, item_, extra_attrs) =
7304 self.parse_item_mod(&attrs[..])?;
7305 let prev_span = self.prev_span;
7306 let item = self.mk_item(lo.to(prev_span),
7310 maybe_append(attrs, extra_attrs));
7311 return Ok(Some(item));
7313 if let Some(type_) = self.eat_type() {
7314 let (ident, alias, generics) = type_?;
7316 let item_ = match alias {
7317 AliasKind::Weak(ty) => ItemKind::Ty(ty, generics),
7318 AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics),
7320 let prev_span = self.prev_span;
7321 let item = self.mk_item(lo.to(prev_span),
7326 return Ok(Some(item));
7328 if self.eat_keyword(keywords::Enum) {
7330 let (ident, item_, extra_attrs) = self.parse_item_enum()?;
7331 let prev_span = self.prev_span;
7332 let item = self.mk_item(lo.to(prev_span),
7336 maybe_append(attrs, extra_attrs));
7337 return Ok(Some(item));
7339 if self.check_keyword(keywords::Trait)
7340 || (self.check_keyword(keywords::Auto)
7341 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
7343 let is_auto = if self.eat_keyword(keywords::Trait) {
7346 self.expect_keyword(keywords::Auto)?;
7347 self.expect_keyword(keywords::Trait)?;
7351 let (ident, item_, extra_attrs) =
7352 self.parse_item_trait(is_auto, Unsafety::Normal)?;
7353 let prev_span = self.prev_span;
7354 let item = self.mk_item(lo.to(prev_span),
7358 maybe_append(attrs, extra_attrs));
7359 return Ok(Some(item));
7361 if self.eat_keyword(keywords::Struct) {
7363 let (ident, item_, extra_attrs) = self.parse_item_struct()?;
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.is_union_item() {
7375 let (ident, item_, extra_attrs) = self.parse_item_union()?;
7376 let prev_span = self.prev_span;
7377 let item = self.mk_item(lo.to(prev_span),
7381 maybe_append(attrs, extra_attrs));
7382 return Ok(Some(item));
7384 if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, lo)? {
7385 return Ok(Some(macro_def));
7388 // Verify whether we have encountered a struct or method definition where the user forgot to
7389 // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
7390 if visibility.node.is_pub() &&
7391 self.check_ident() &&
7392 self.look_ahead(1, |t| *t != token::Not)
7394 // Space between `pub` keyword and the identifier
7397 // ^^^ `sp` points here
7398 let sp = self.prev_span.between(self.span);
7399 let full_sp = self.prev_span.to(self.span);
7400 let ident_sp = self.span;
7401 if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
7402 // possible public struct definition where `struct` was forgotten
7403 let ident = self.parse_ident().unwrap();
7404 let msg = format!("add `struct` here to parse `{}` as a public struct",
7406 let mut err = self.diagnostic()
7407 .struct_span_err(sp, "missing `struct` for struct definition");
7408 err.span_suggestion_short_with_applicability(
7409 sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
7412 } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
7413 let ident = self.parse_ident().unwrap();
7415 let kw_name = if let Ok(Some(_)) = self.parse_self_arg() {
7420 self.consume_block(token::Paren);
7421 let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) {
7422 self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]);
7424 ("fn", kw_name, false)
7425 } else if self.check(&token::OpenDelim(token::Brace)) {
7427 ("fn", kw_name, false)
7428 } else if self.check(&token::Colon) {
7432 ("fn` or `struct", "function or struct", true)
7434 self.consume_block(token::Brace);
7436 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7437 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7439 let suggestion = format!("add `{}` here to parse `{}` as a public {}",
7443 err.span_suggestion_short_with_applicability(
7444 sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
7447 if let Ok(snippet) = self.sess.source_map().span_to_snippet(ident_sp) {
7448 err.span_suggestion_with_applicability(
7450 "if you meant to call a macro, try",
7451 format!("{}!", snippet),
7452 // this is the `ambiguous` conditional branch
7453 Applicability::MaybeIncorrect
7456 err.help("if you meant to call a macro, remove the `pub` \
7457 and add a trailing `!` after the identifier");
7461 } else if self.look_ahead(1, |t| *t == token::Lt) {
7462 let ident = self.parse_ident().unwrap();
7463 self.eat_to_tokens(&[&token::Gt]);
7465 let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) {
7466 if let Ok(Some(_)) = self.parse_self_arg() {
7467 ("fn", "method", false)
7469 ("fn", "function", false)
7471 } else if self.check(&token::OpenDelim(token::Brace)) {
7472 ("struct", "struct", false)
7474 ("fn` or `struct", "function or struct", true)
7476 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7477 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7479 err.span_suggestion_short_with_applicability(
7481 &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name),
7482 format!(" {} ", kw),
7483 Applicability::MachineApplicable,
7489 self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, visibility)
7492 /// Parse a foreign item.
7493 crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> {
7494 maybe_whole!(self, NtForeignItem, |ni| ni);
7496 let attrs = self.parse_outer_attributes()?;
7498 let visibility = self.parse_visibility(false)?;
7500 // FOREIGN STATIC ITEM
7501 // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
7502 if self.check_keyword(keywords::Static) || self.token.is_keyword(keywords::Const) {
7503 if self.token.is_keyword(keywords::Const) {
7505 .struct_span_err(self.span, "extern items cannot be `const`")
7506 .span_suggestion_with_applicability(
7508 "try using a static value",
7509 "static".to_owned(),
7510 Applicability::MachineApplicable
7513 self.bump(); // `static` or `const`
7514 return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
7516 // FOREIGN FUNCTION ITEM
7517 if self.check_keyword(keywords::Fn) {
7518 return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?);
7520 // FOREIGN TYPE ITEM
7521 if self.check_keyword(keywords::Type) {
7522 return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
7525 match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
7529 ident: keywords::Invalid.ident(),
7530 span: lo.to(self.prev_span),
7531 id: ast::DUMMY_NODE_ID,
7534 node: ForeignItemKind::Macro(mac),
7539 if !attrs.is_empty() {
7540 self.expected_item_err(&attrs);
7548 /// This is the fall-through for parsing items.
7549 fn parse_macro_use_or_failure(
7551 attrs: Vec<Attribute> ,
7552 macros_allowed: bool,
7553 attributes_allowed: bool,
7555 visibility: Visibility
7556 ) -> PResult<'a, Option<P<Item>>> {
7557 if macros_allowed && self.token.is_path_start() {
7558 // MACRO INVOCATION ITEM
7560 let prev_span = self.prev_span;
7561 self.complain_if_pub_macro(&visibility.node, prev_span);
7563 let mac_lo = self.span;
7566 let pth = self.parse_path(PathStyle::Mod)?;
7567 self.expect(&token::Not)?;
7569 // a 'special' identifier (like what `macro_rules!` uses)
7570 // is optional. We should eventually unify invoc syntax
7572 let id = if self.token.is_ident() {
7575 keywords::Invalid.ident() // no special identifier
7577 // eat a matched-delimiter token tree:
7578 let (delim, tts) = self.expect_delimited_token_tree()?;
7579 if delim != MacDelimiter::Brace {
7580 if !self.eat(&token::Semi) {
7581 self.span_err(self.prev_span,
7582 "macros that expand to items must either \
7583 be surrounded with braces or followed by \
7588 let hi = self.prev_span;
7589 let mac = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim });
7590 let item = self.mk_item(lo.to(hi), id, ItemKind::Mac(mac), visibility, attrs);
7591 return Ok(Some(item));
7594 // FAILURE TO PARSE ITEM
7595 match visibility.node {
7596 VisibilityKind::Inherited => {}
7598 return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
7602 if !attributes_allowed && !attrs.is_empty() {
7603 self.expected_item_err(&attrs);
7608 /// Parse a macro invocation inside a `trait`, `impl` or `extern` block
7609 fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
7610 at_end: &mut bool) -> PResult<'a, Option<Mac>>
7612 if self.token.is_path_start() && !self.is_extern_non_path() {
7613 let prev_span = self.prev_span;
7615 let pth = self.parse_path(PathStyle::Mod)?;
7617 if pth.segments.len() == 1 {
7618 if !self.eat(&token::Not) {
7619 return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
7622 self.expect(&token::Not)?;
7625 if let Some(vis) = vis {
7626 self.complain_if_pub_macro(&vis.node, prev_span);
7631 // eat a matched-delimiter token tree:
7632 let (delim, tts) = self.expect_delimited_token_tree()?;
7633 if delim != MacDelimiter::Brace {
7634 self.expect(&token::Semi)?
7637 Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim })))
7643 fn collect_tokens<F, R>(&mut self, f: F) -> PResult<'a, (R, TokenStream)>
7644 where F: FnOnce(&mut Self) -> PResult<'a, R>
7646 // Record all tokens we parse when parsing this item.
7647 let mut tokens = Vec::new();
7648 let prev_collecting = match self.token_cursor.frame.last_token {
7649 LastToken::Collecting(ref mut list) => {
7650 Some(mem::replace(list, Vec::new()))
7652 LastToken::Was(ref mut last) => {
7653 tokens.extend(last.take());
7657 self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
7658 let prev = self.token_cursor.stack.len();
7660 let last_token = if self.token_cursor.stack.len() == prev {
7661 &mut self.token_cursor.frame.last_token
7663 &mut self.token_cursor.stack[prev].last_token
7666 // Pull our the toekns that we've collected from the call to `f` above
7667 let mut collected_tokens = match *last_token {
7668 LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()),
7669 LastToken::Was(_) => panic!("our vector went away?"),
7672 // If we're not at EOF our current token wasn't actually consumed by
7673 // `f`, but it'll still be in our list that we pulled out. In that case
7675 let extra_token = if self.token != token::Eof {
7676 collected_tokens.pop()
7681 // If we were previously collecting tokens, then this was a recursive
7682 // call. In that case we need to record all the tokens we collected in
7683 // our parent list as well. To do that we push a clone of our stream
7684 // onto the previous list.
7685 let stream = collected_tokens.into_iter().collect::<TokenStream>();
7686 match prev_collecting {
7688 list.push(stream.clone());
7689 list.extend(extra_token);
7690 *last_token = LastToken::Collecting(list);
7693 *last_token = LastToken::Was(extra_token);
7700 pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
7701 let attrs = self.parse_outer_attributes()?;
7702 self.parse_item_(attrs, true, false)
7706 fn is_import_coupler(&mut self) -> bool {
7707 self.check(&token::ModSep) &&
7708 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
7709 *t == token::BinOp(token::Star))
7714 /// USE_TREE = [`::`] `*` |
7715 /// [`::`] `{` USE_TREE_LIST `}` |
7717 /// PATH `::` `{` USE_TREE_LIST `}` |
7718 /// PATH [`as` IDENT]
7719 fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
7722 let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
7723 let kind = if self.check(&token::OpenDelim(token::Brace)) ||
7724 self.check(&token::BinOp(token::Star)) ||
7725 self.is_import_coupler() {
7726 // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
7727 let mod_sep_ctxt = self.span.ctxt();
7728 if self.eat(&token::ModSep) {
7729 prefix.segments.push(
7730 PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
7734 if self.eat(&token::BinOp(token::Star)) {
7737 UseTreeKind::Nested(self.parse_use_tree_list()?)
7740 // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
7741 prefix = self.parse_path(PathStyle::Mod)?;
7743 if self.eat(&token::ModSep) {
7744 if self.eat(&token::BinOp(token::Star)) {
7747 UseTreeKind::Nested(self.parse_use_tree_list()?)
7750 UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID)
7754 Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
7757 /// Parse UseTreeKind::Nested(list)
7759 /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
7760 fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
7761 self.parse_unspanned_seq(&token::OpenDelim(token::Brace),
7762 &token::CloseDelim(token::Brace),
7763 SeqSep::trailing_allowed(token::Comma), |this| {
7764 Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID))
7768 fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
7769 if self.eat_keyword(keywords::As) {
7770 self.parse_ident_or_underscore().map(Some)
7776 /// Parses a source module as a crate. This is the main
7777 /// entry point for the parser.
7778 pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
7781 attrs: self.parse_inner_attributes()?,
7782 module: self.parse_mod_items(&token::Eof, lo)?,
7783 span: lo.to(self.span),
7787 pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
7788 let ret = match self.token {
7789 token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf),
7790 token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf),
7797 pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
7798 match self.parse_optional_str() {
7799 Some((s, style, suf)) => {
7800 let sp = self.prev_span;
7801 self.expect_no_suffix(sp, "string literal", suf);
7805 let msg = "expected string literal";
7806 let mut err = self.fatal(msg);
7807 err.span_label(self.span, msg);