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::Comma &&
1870 self.token != token::CloseDelim(token::Paren) {
1871 // This wasn't actually a type, but a pattern looking like a type,
1872 // so we are going to rollback and re-parse for recovery.
1873 ty = self.unexpected();
1877 let ident = Ident::new(keywords::Invalid.name(), self.prev_span);
1879 id: ast::DUMMY_NODE_ID,
1880 node: PatKind::Ident(
1881 BindingMode::ByValue(Mutability::Immutable), ident, None),
1887 // Recover from attempting to parse the argument as a type without pattern.
1889 mem::replace(self, parser_snapshot_before_ty);
1890 let pat = self.parse_pat(Some("argument name"))?;
1891 self.expect(&token::Colon)?;
1892 let ty = self.parse_ty()?;
1894 let mut err = self.diagnostic().struct_span_err_with_code(
1896 "patterns aren't allowed in methods without bodies",
1897 DiagnosticId::Error("E0642".into()),
1899 err.span_suggestion_short_with_applicability(
1901 "give this argument a name or use an underscore to ignore it",
1903 Applicability::MachineApplicable,
1907 // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
1909 node: PatKind::Wild,
1911 id: ast::DUMMY_NODE_ID
1918 Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID })
1921 /// Parse a single function argument
1922 crate fn parse_arg(&mut self) -> PResult<'a, Arg> {
1923 self.parse_arg_general(true, false)
1926 /// Parse an argument in a lambda header e.g., |arg, arg|
1927 fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
1928 let pat = self.parse_pat(Some("argument name"))?;
1929 let t = if self.eat(&token::Colon) {
1933 id: ast::DUMMY_NODE_ID,
1934 node: TyKind::Infer,
1935 span: self.prev_span,
1941 id: ast::DUMMY_NODE_ID
1945 fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
1946 if self.eat(&token::Semi) {
1947 Ok(Some(self.parse_expr()?))
1953 /// Matches token_lit = LIT_INTEGER | ...
1954 fn parse_lit_token(&mut self) -> PResult<'a, LitKind> {
1955 let out = match self.token {
1956 token::Interpolated(ref nt) => match nt.0 {
1957 token::NtExpr(ref v) | token::NtLiteral(ref v) => match v.node {
1958 ExprKind::Lit(ref lit) => { lit.node.clone() }
1959 _ => { return self.unexpected_last(&self.token); }
1961 _ => { return self.unexpected_last(&self.token); }
1963 token::Literal(lit, suf) => {
1964 let diag = Some((self.span, &self.sess.span_diagnostic));
1965 let (suffix_illegal, result) = parse::lit_token(lit, suf, diag);
1969 self.expect_no_suffix(sp, lit.literal_name(), suf)
1974 _ => { return self.unexpected_last(&self.token); }
1981 /// Matches lit = true | false | token_lit
1982 crate fn parse_lit(&mut self) -> PResult<'a, Lit> {
1984 let lit = if self.eat_keyword(keywords::True) {
1986 } else if self.eat_keyword(keywords::False) {
1987 LitKind::Bool(false)
1989 let lit = self.parse_lit_token()?;
1992 Ok(source_map::Spanned { node: lit, span: lo.to(self.prev_span) })
1995 /// matches '-' lit | lit (cf. ast_validation::AstValidator::check_expr_within_pat)
1996 crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
1997 maybe_whole_expr!(self);
1999 let minus_lo = self.span;
2000 let minus_present = self.eat(&token::BinOp(token::Minus));
2002 let literal = self.parse_lit()?;
2003 let hi = self.prev_span;
2004 let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
2007 let minus_hi = self.prev_span;
2008 let unary = self.mk_unary(UnOp::Neg, expr);
2009 Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
2015 fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
2017 token::Ident(ident, _) if self.token.is_path_segment_keyword() => {
2018 let span = self.span;
2020 Ok(Ident::new(ident.name, span))
2022 _ => self.parse_ident(),
2026 fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
2028 token::Ident(ident, false) if ident.name == keywords::Underscore.name() => {
2029 let span = self.span;
2031 Ok(Ident::new(ident.name, span))
2033 _ => self.parse_ident(),
2037 /// Parses qualified path.
2038 /// Assumes that the leading `<` has been parsed already.
2040 /// `qualified_path = <type [as trait_ref]>::path`
2045 /// `<T as U>::F::a<S>` (without disambiguator)
2046 /// `<T as U>::F::a::<S>` (with disambiguator)
2047 fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::Path)> {
2048 let lo = self.prev_span;
2049 let ty = self.parse_ty()?;
2051 // `path` will contain the prefix of the path up to the `>`,
2052 // if any (e.g., `U` in the `<T as U>::*` examples
2053 // above). `path_span` has the span of that path, or an empty
2054 // span in the case of something like `<T>::Bar`.
2055 let (mut path, path_span);
2056 if self.eat_keyword(keywords::As) {
2057 let path_lo = self.span;
2058 path = self.parse_path(PathStyle::Type)?;
2059 path_span = path_lo.to(self.prev_span);
2061 path = ast::Path { segments: Vec::new(), span: syntax_pos::DUMMY_SP };
2062 path_span = self.span.to(self.span);
2065 self.expect(&token::Gt)?;
2066 self.expect(&token::ModSep)?;
2068 let qself = QSelf { ty, path_span, position: path.segments.len() };
2069 self.parse_path_segments(&mut path.segments, style, true)?;
2071 Ok((qself, ast::Path { segments: path.segments, span: lo.to(self.prev_span) }))
2074 /// Parses simple paths.
2076 /// `path = [::] segment+`
2077 /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
2080 /// `a::b::C<D>` (without disambiguator)
2081 /// `a::b::C::<D>` (with disambiguator)
2082 /// `Fn(Args)` (without disambiguator)
2083 /// `Fn::(Args)` (with disambiguator)
2084 pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2085 self.parse_path_common(style, true)
2088 crate fn parse_path_common(&mut self, style: PathStyle, enable_warning: bool)
2089 -> PResult<'a, ast::Path> {
2090 maybe_whole!(self, NtPath, |path| {
2091 if style == PathStyle::Mod &&
2092 path.segments.iter().any(|segment| segment.args.is_some()) {
2093 self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
2098 let lo = self.meta_var_span.unwrap_or(self.span);
2099 let mut segments = Vec::new();
2100 let mod_sep_ctxt = self.span.ctxt();
2101 if self.eat(&token::ModSep) {
2102 segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
2104 self.parse_path_segments(&mut segments, style, enable_warning)?;
2106 Ok(ast::Path { segments, span: lo.to(self.prev_span) })
2109 /// Like `parse_path`, but also supports parsing `Word` meta items into paths for back-compat.
2110 /// This is used when parsing derive macro paths in `#[derive]` attributes.
2111 pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
2112 let meta_ident = match self.token {
2113 token::Interpolated(ref nt) => match nt.0 {
2114 token::NtMeta(ref meta) => match meta.node {
2115 ast::MetaItemKind::Word => Some(meta.ident.clone()),
2122 if let Some(path) = meta_ident {
2126 self.parse_path(style)
2129 fn parse_path_segments(&mut self,
2130 segments: &mut Vec<PathSegment>,
2132 enable_warning: bool)
2133 -> PResult<'a, ()> {
2135 segments.push(self.parse_path_segment(style, enable_warning)?);
2137 if self.is_import_coupler() || !self.eat(&token::ModSep) {
2143 fn parse_path_segment(&mut self, style: PathStyle, enable_warning: bool)
2144 -> PResult<'a, PathSegment> {
2145 let ident = self.parse_path_segment_ident()?;
2147 let is_args_start = |token: &token::Token| match *token {
2148 token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren) => true,
2151 let check_args_start = |this: &mut Self| {
2152 this.expected_tokens.extend_from_slice(
2153 &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
2155 is_args_start(&this.token)
2158 Ok(if style == PathStyle::Type && check_args_start(self) ||
2159 style != PathStyle::Mod && self.check(&token::ModSep)
2160 && self.look_ahead(1, |t| is_args_start(t)) {
2161 // Generic arguments are found - `<`, `(`, `::<` or `::(`.
2163 if self.eat(&token::ModSep) && style == PathStyle::Type && enable_warning {
2164 self.diagnostic().struct_span_warn(self.prev_span, "unnecessary path disambiguator")
2165 .span_label(self.prev_span, "try removing `::`").emit();
2168 let args = if self.eat_lt() {
2170 let (args, bindings) = self.parse_generic_args()?;
2172 let span = lo.to(self.prev_span);
2173 AngleBracketedArgs { args, bindings, span }.into()
2177 let inputs = self.parse_seq_to_before_tokens(
2178 &[&token::CloseDelim(token::Paren)],
2179 SeqSep::trailing_allowed(token::Comma),
2180 TokenExpectType::Expect,
2183 let span = lo.to(self.prev_span);
2184 let output = if self.eat(&token::RArrow) {
2185 Some(self.parse_ty_common(false, false)?)
2189 ParenthesisedArgs { inputs, output, span }.into()
2192 PathSegment { ident, args, id: ast::DUMMY_NODE_ID }
2194 // Generic arguments are not found.
2195 PathSegment::from_ident(ident)
2199 crate fn check_lifetime(&mut self) -> bool {
2200 self.expected_tokens.push(TokenType::Lifetime);
2201 self.token.is_lifetime()
2204 /// Parse single lifetime 'a or panic.
2205 crate fn expect_lifetime(&mut self) -> Lifetime {
2206 if let Some(ident) = self.token.lifetime() {
2207 let span = self.span;
2209 Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
2211 self.span_bug(self.span, "not a lifetime")
2215 fn eat_label(&mut self) -> Option<Label> {
2216 if let Some(ident) = self.token.lifetime() {
2217 let span = self.span;
2219 Some(Label { ident: Ident::new(ident.name, span) })
2225 /// Parse mutability (`mut` or nothing).
2226 fn parse_mutability(&mut self) -> Mutability {
2227 if self.eat_keyword(keywords::Mut) {
2230 Mutability::Immutable
2234 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
2235 if let token::Literal(token::Integer(name), None) = self.token {
2237 Ok(Ident::new(name, self.prev_span))
2239 self.parse_ident_common(false)
2243 /// Parse ident (COLON expr)?
2244 fn parse_field(&mut self) -> PResult<'a, Field> {
2245 let attrs = self.parse_outer_attributes()?;
2248 // Check if a colon exists one ahead. This means we're parsing a fieldname.
2249 let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
2250 let fieldname = self.parse_field_name()?;
2252 (fieldname, self.parse_expr()?, false)
2254 let fieldname = self.parse_ident_common(false)?;
2256 // Mimic `x: x` for the `x` field shorthand.
2257 let path = ast::Path::from_ident(fieldname);
2258 let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
2259 (fieldname, expr, true)
2263 span: lo.to(expr.span),
2266 attrs: attrs.into(),
2270 fn mk_expr(&mut self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
2271 P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID })
2274 fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
2275 ExprKind::Unary(unop, expr)
2278 fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2279 ExprKind::Binary(binop, lhs, rhs)
2282 fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
2283 ExprKind::Call(f, args)
2286 fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
2287 ExprKind::Index(expr, idx)
2290 fn mk_range(&mut self,
2291 start: Option<P<Expr>>,
2292 end: Option<P<Expr>>,
2293 limits: RangeLimits)
2294 -> PResult<'a, ast::ExprKind> {
2295 if end.is_none() && limits == RangeLimits::Closed {
2296 Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd))
2298 Ok(ExprKind::Range(start, end, limits))
2302 fn mk_assign_op(&mut self, binop: ast::BinOp,
2303 lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2304 ExprKind::AssignOp(binop, lhs, rhs)
2307 pub fn mk_mac_expr(&mut self, span: Span, m: Mac_, attrs: ThinVec<Attribute>) -> P<Expr> {
2309 id: ast::DUMMY_NODE_ID,
2310 node: ExprKind::Mac(source_map::Spanned {node: m, span: span}),
2316 fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, ThinTokenStream)> {
2317 let delim = match self.token {
2318 token::OpenDelim(delim) => delim,
2320 let msg = "expected open delimiter";
2321 let mut err = self.fatal(msg);
2322 err.span_label(self.span, msg);
2326 let tts = match self.parse_token_tree() {
2327 TokenTree::Delimited(_, _, tts) => tts,
2328 _ => unreachable!(),
2330 let delim = match delim {
2331 token::Paren => MacDelimiter::Parenthesis,
2332 token::Bracket => MacDelimiter::Bracket,
2333 token::Brace => MacDelimiter::Brace,
2334 token::NoDelim => self.bug("unexpected no delimiter"),
2336 Ok((delim, tts.stream().into()))
2339 /// At the bottom (top?) of the precedence hierarchy,
2340 /// parse things like parenthesized exprs,
2341 /// macros, return, etc.
2343 /// N.B., this does not parse outer attributes,
2344 /// and is private because it only works
2345 /// correctly if called from parse_dot_or_call_expr().
2346 fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
2347 maybe_whole_expr!(self);
2349 // Outer attributes are already parsed and will be
2350 // added to the return value after the fact.
2352 // Therefore, prevent sub-parser from parsing
2353 // attributes by giving them a empty "already parsed" list.
2354 let mut attrs = ThinVec::new();
2357 let mut hi = self.span;
2361 // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2363 token::OpenDelim(token::Paren) => {
2366 attrs.extend(self.parse_inner_attributes()?);
2368 // (e) is parenthesized e
2369 // (e,) is a tuple with only one field, e
2370 let mut es = vec![];
2371 let mut trailing_comma = false;
2372 while self.token != token::CloseDelim(token::Paren) {
2373 es.push(self.parse_expr()?);
2374 self.expect_one_of(&[], &[token::Comma, token::CloseDelim(token::Paren)])?;
2375 if self.eat(&token::Comma) {
2376 trailing_comma = true;
2378 trailing_comma = false;
2384 hi = self.prev_span;
2385 ex = if es.len() == 1 && !trailing_comma {
2386 ExprKind::Paren(es.into_iter().nth(0).unwrap())
2391 token::OpenDelim(token::Brace) => {
2392 return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
2394 token::BinOp(token::Or) | token::OrOr => {
2395 return self.parse_lambda_expr(attrs);
2397 token::OpenDelim(token::Bracket) => {
2400 attrs.extend(self.parse_inner_attributes()?);
2402 if self.eat(&token::CloseDelim(token::Bracket)) {
2404 ex = ExprKind::Array(Vec::new());
2407 let first_expr = self.parse_expr()?;
2408 if self.eat(&token::Semi) {
2409 // Repeating array syntax: [ 0; 512 ]
2410 let count = AnonConst {
2411 id: ast::DUMMY_NODE_ID,
2412 value: self.parse_expr()?,
2414 self.expect(&token::CloseDelim(token::Bracket))?;
2415 ex = ExprKind::Repeat(first_expr, count);
2416 } else if self.eat(&token::Comma) {
2417 // Vector with two or more elements.
2418 let remaining_exprs = self.parse_seq_to_end(
2419 &token::CloseDelim(token::Bracket),
2420 SeqSep::trailing_allowed(token::Comma),
2421 |p| Ok(p.parse_expr()?)
2423 let mut exprs = vec![first_expr];
2424 exprs.extend(remaining_exprs);
2425 ex = ExprKind::Array(exprs);
2427 // Vector with one element.
2428 self.expect(&token::CloseDelim(token::Bracket))?;
2429 ex = ExprKind::Array(vec![first_expr]);
2432 hi = self.prev_span;
2436 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
2438 return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
2440 if self.span.rust_2018() && self.check_keyword(keywords::Async)
2442 if self.is_async_block() { // check for `async {` and `async move {`
2443 return self.parse_async_block(attrs);
2445 return self.parse_lambda_expr(attrs);
2448 if self.check_keyword(keywords::Move) || self.check_keyword(keywords::Static) {
2449 return self.parse_lambda_expr(attrs);
2451 if self.eat_keyword(keywords::If) {
2452 return self.parse_if_expr(attrs);
2454 if self.eat_keyword(keywords::For) {
2455 let lo = self.prev_span;
2456 return self.parse_for_expr(None, lo, attrs);
2458 if self.eat_keyword(keywords::While) {
2459 let lo = self.prev_span;
2460 return self.parse_while_expr(None, lo, attrs);
2462 if let Some(label) = self.eat_label() {
2463 let lo = label.ident.span;
2464 self.expect(&token::Colon)?;
2465 if self.eat_keyword(keywords::While) {
2466 return self.parse_while_expr(Some(label), lo, attrs)
2468 if self.eat_keyword(keywords::For) {
2469 return self.parse_for_expr(Some(label), lo, attrs)
2471 if self.eat_keyword(keywords::Loop) {
2472 return self.parse_loop_expr(Some(label), lo, attrs)
2474 if self.token == token::OpenDelim(token::Brace) {
2475 return self.parse_block_expr(Some(label),
2477 BlockCheckMode::Default,
2480 let msg = "expected `while`, `for`, `loop` or `{` after a label";
2481 let mut err = self.fatal(msg);
2482 err.span_label(self.span, msg);
2485 if self.eat_keyword(keywords::Loop) {
2486 let lo = self.prev_span;
2487 return self.parse_loop_expr(None, lo, attrs);
2489 if self.eat_keyword(keywords::Continue) {
2490 let label = self.eat_label();
2491 let ex = ExprKind::Continue(label);
2492 let hi = self.prev_span;
2493 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2495 if self.eat_keyword(keywords::Match) {
2496 let match_sp = self.prev_span;
2497 return self.parse_match_expr(attrs).map_err(|mut err| {
2498 err.span_label(match_sp, "while parsing this match expression");
2502 if self.eat_keyword(keywords::Unsafe) {
2503 return self.parse_block_expr(
2506 BlockCheckMode::Unsafe(ast::UserProvided),
2509 if self.is_do_catch_block() {
2510 let mut db = self.fatal("found removed `do catch` syntax");
2511 db.help("Following RFC #2388, the new non-placeholder syntax is `try`");
2514 if self.is_try_block() {
2516 assert!(self.eat_keyword(keywords::Try));
2517 return self.parse_try_block(lo, attrs);
2519 if self.eat_keyword(keywords::Return) {
2520 if self.token.can_begin_expr() {
2521 let e = self.parse_expr()?;
2523 ex = ExprKind::Ret(Some(e));
2525 ex = ExprKind::Ret(None);
2527 } else if self.eat_keyword(keywords::Break) {
2528 let label = self.eat_label();
2529 let e = if self.token.can_begin_expr()
2530 && !(self.token == token::OpenDelim(token::Brace)
2531 && self.restrictions.contains(
2532 Restrictions::NO_STRUCT_LITERAL)) {
2533 Some(self.parse_expr()?)
2537 ex = ExprKind::Break(label, e);
2538 hi = self.prev_span;
2539 } else if self.eat_keyword(keywords::Yield) {
2540 if self.token.can_begin_expr() {
2541 let e = self.parse_expr()?;
2543 ex = ExprKind::Yield(Some(e));
2545 ex = ExprKind::Yield(None);
2547 } else if self.token.is_keyword(keywords::Let) {
2548 // Catch this syntax error here, instead of in `parse_ident`, so
2549 // that we can explicitly mention that let is not to be used as an expression
2550 let mut db = self.fatal("expected expression, found statement (`let`)");
2551 db.span_label(self.span, "expected expression");
2552 db.note("variable declaration using `let` is a statement");
2554 } else if self.token.is_path_start() {
2555 let pth = self.parse_path(PathStyle::Expr)?;
2557 // `!`, as an operator, is prefix, so we know this isn't that
2558 if self.eat(&token::Not) {
2559 // MACRO INVOCATION expression
2560 let (delim, tts) = self.expect_delimited_token_tree()?;
2561 let hi = self.prev_span;
2562 let node = Mac_ { path: pth, tts, delim };
2563 return Ok(self.mk_mac_expr(lo.to(hi), node, attrs))
2565 if self.check(&token::OpenDelim(token::Brace)) {
2566 // This is a struct literal, unless we're prohibited
2567 // from parsing struct literals here.
2568 let prohibited = self.restrictions.contains(
2569 Restrictions::NO_STRUCT_LITERAL
2572 return self.parse_struct_expr(lo, pth, attrs);
2577 ex = ExprKind::Path(None, pth);
2579 match self.parse_literal_maybe_minus() {
2582 ex = expr.node.clone();
2585 self.cancel(&mut err);
2586 let msg = format!("expected expression, found {}",
2587 self.this_token_descr());
2588 let mut err = self.fatal(&msg);
2589 err.span_label(self.span, "expected expression");
2597 let expr = Expr { node: ex, span: lo.to(hi), id: ast::DUMMY_NODE_ID, attrs };
2598 let expr = self.maybe_recover_from_bad_qpath(expr, true)?;
2603 fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Attribute>)
2604 -> PResult<'a, P<Expr>> {
2605 let struct_sp = lo.to(self.prev_span);
2607 let mut fields = Vec::new();
2608 let mut base = None;
2610 attrs.extend(self.parse_inner_attributes()?);
2612 while self.token != token::CloseDelim(token::Brace) {
2613 if self.eat(&token::DotDot) {
2614 let exp_span = self.prev_span;
2615 match self.parse_expr() {
2621 self.recover_stmt();
2624 if self.token == token::Comma {
2625 let mut err = self.sess.span_diagnostic.mut_span_err(
2626 exp_span.to(self.prev_span),
2627 "cannot use a comma after the base struct",
2629 err.span_suggestion_short_with_applicability(
2631 "remove this comma",
2633 Applicability::MachineApplicable
2635 err.note("the base struct must always be the last field");
2637 self.recover_stmt();
2642 match self.parse_field() {
2643 Ok(f) => fields.push(f),
2645 e.span_label(struct_sp, "while parsing this struct");
2648 // If the next token is a comma, then try to parse
2649 // what comes next as additional fields, rather than
2650 // bailing out until next `}`.
2651 if self.token != token::Comma {
2652 self.recover_stmt();
2658 match self.expect_one_of(&[token::Comma],
2659 &[token::CloseDelim(token::Brace)]) {
2663 self.recover_stmt();
2669 let span = lo.to(self.span);
2670 self.expect(&token::CloseDelim(token::Brace))?;
2671 return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
2674 fn parse_or_use_outer_attributes(&mut self,
2675 already_parsed_attrs: Option<ThinVec<Attribute>>)
2676 -> PResult<'a, ThinVec<Attribute>> {
2677 if let Some(attrs) = already_parsed_attrs {
2680 self.parse_outer_attributes().map(|a| a.into())
2684 /// Parse a block or unsafe block
2685 fn parse_block_expr(&mut self, opt_label: Option<Label>,
2686 lo: Span, blk_mode: BlockCheckMode,
2687 outer_attrs: ThinVec<Attribute>)
2688 -> PResult<'a, P<Expr>> {
2689 self.expect(&token::OpenDelim(token::Brace))?;
2691 let mut attrs = outer_attrs;
2692 attrs.extend(self.parse_inner_attributes()?);
2694 let blk = self.parse_block_tail(lo, blk_mode)?;
2695 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs));
2698 /// parse a.b or a(13) or a[4] or just a
2699 fn parse_dot_or_call_expr(&mut self,
2700 already_parsed_attrs: Option<ThinVec<Attribute>>)
2701 -> PResult<'a, P<Expr>> {
2702 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2704 let b = self.parse_bottom_expr();
2705 let (span, b) = self.interpolated_or_expr_span(b)?;
2706 self.parse_dot_or_call_expr_with(b, span, attrs)
2709 fn parse_dot_or_call_expr_with(&mut self,
2712 mut attrs: ThinVec<Attribute>)
2713 -> PResult<'a, P<Expr>> {
2714 // Stitch the list of outer attributes onto the return value.
2715 // A little bit ugly, but the best way given the current code
2717 self.parse_dot_or_call_expr_with_(e0, lo)
2719 expr.map(|mut expr| {
2720 attrs.extend::<Vec<_>>(expr.attrs.into());
2723 ExprKind::If(..) | ExprKind::IfLet(..) => {
2724 if !expr.attrs.is_empty() {
2725 // Just point to the first attribute in there...
2726 let span = expr.attrs[0].span;
2729 "attributes are not yet allowed on `if` \
2740 // Assuming we have just parsed `.`, continue parsing into an expression.
2741 fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2742 let segment = self.parse_path_segment(PathStyle::Expr, true)?;
2743 Ok(match self.token {
2744 token::OpenDelim(token::Paren) => {
2745 // Method call `expr.f()`
2746 let mut args = self.parse_unspanned_seq(
2747 &token::OpenDelim(token::Paren),
2748 &token::CloseDelim(token::Paren),
2749 SeqSep::trailing_allowed(token::Comma),
2750 |p| Ok(p.parse_expr()?)
2752 args.insert(0, self_arg);
2754 let span = lo.to(self.prev_span);
2755 self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
2758 // Field access `expr.f`
2759 if let Some(args) = segment.args {
2760 self.span_err(args.span(),
2761 "field expressions may not have generic arguments");
2764 let span = lo.to(self.prev_span);
2765 self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
2770 fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2775 while self.eat(&token::Question) {
2776 let hi = self.prev_span;
2777 e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
2781 if self.eat(&token::Dot) {
2783 token::Ident(..) => {
2784 e = self.parse_dot_suffix(e, lo)?;
2786 token::Literal(token::Integer(name), _) => {
2787 let span = self.span;
2789 let field = ExprKind::Field(e, Ident::new(name, span));
2790 e = self.mk_expr(lo.to(span), field, ThinVec::new());
2792 token::Literal(token::Float(n), _suf) => {
2794 let fstr = n.as_str();
2795 let mut err = self.diagnostic()
2796 .struct_span_err(self.prev_span, &format!("unexpected token: `{}`", n));
2797 err.span_label(self.prev_span, "unexpected token");
2798 if fstr.chars().all(|x| "0123456789.".contains(x)) {
2799 let float = match fstr.parse::<f64>().ok() {
2803 let sugg = pprust::to_string(|s| {
2804 use print::pprust::PrintState;
2808 s.print_usize(float.trunc() as usize)?;
2811 s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
2813 err.span_suggestion_with_applicability(
2814 lo.to(self.prev_span),
2815 "try parenthesizing the first index",
2817 Applicability::MachineApplicable
2824 // FIXME Could factor this out into non_fatal_unexpected or something.
2825 let actual = self.this_token_to_string();
2826 self.span_err(self.span, &format!("unexpected token: `{}`", actual));
2831 if self.expr_is_complete(&e) { break; }
2834 token::OpenDelim(token::Paren) => {
2835 let es = self.parse_unspanned_seq(
2836 &token::OpenDelim(token::Paren),
2837 &token::CloseDelim(token::Paren),
2838 SeqSep::trailing_allowed(token::Comma),
2839 |p| Ok(p.parse_expr()?)
2841 hi = self.prev_span;
2843 let nd = self.mk_call(e, es);
2844 e = self.mk_expr(lo.to(hi), nd, ThinVec::new());
2848 // Could be either an index expression or a slicing expression.
2849 token::OpenDelim(token::Bracket) => {
2851 let ix = self.parse_expr()?;
2853 self.expect(&token::CloseDelim(token::Bracket))?;
2854 let index = self.mk_index(e, ix);
2855 e = self.mk_expr(lo.to(hi), index, ThinVec::new())
2863 crate fn process_potential_macro_variable(&mut self) {
2864 let (token, span) = match self.token {
2865 token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
2866 self.look_ahead(1, |t| t.is_ident()) => {
2868 let name = match self.token {
2869 token::Ident(ident, _) => ident,
2872 let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
2873 err.span_label(self.span, "unknown macro variable");
2878 token::Interpolated(ref nt) => {
2879 self.meta_var_span = Some(self.span);
2880 // Interpolated identifier and lifetime tokens are replaced with usual identifier
2881 // and lifetime tokens, so the former are never encountered during normal parsing.
2883 token::NtIdent(ident, is_raw) => (token::Ident(ident, is_raw), ident.span),
2884 token::NtLifetime(ident) => (token::Lifetime(ident), ident.span),
2894 /// parse a single token tree from the input.
2895 crate fn parse_token_tree(&mut self) -> TokenTree {
2897 token::OpenDelim(..) => {
2898 let frame = mem::replace(&mut self.token_cursor.frame,
2899 self.token_cursor.stack.pop().unwrap());
2900 self.span = frame.span.entire();
2902 TokenTree::Delimited(
2905 frame.tree_cursor.original_stream().into(),
2908 token::CloseDelim(_) | token::Eof => unreachable!(),
2910 let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span);
2912 TokenTree::Token(span, token)
2917 // parse a stream of tokens into a list of TokenTree's,
2919 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
2920 let mut tts = Vec::new();
2921 while self.token != token::Eof {
2922 tts.push(self.parse_token_tree());
2927 pub fn parse_tokens(&mut self) -> TokenStream {
2928 let mut result = Vec::new();
2931 token::Eof | token::CloseDelim(..) => break,
2932 _ => result.push(self.parse_token_tree().into()),
2935 TokenStream::new(result)
2938 /// Parse a prefix-unary-operator expr
2939 fn parse_prefix_expr(&mut self,
2940 already_parsed_attrs: Option<ThinVec<Attribute>>)
2941 -> PResult<'a, P<Expr>> {
2942 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2944 // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2945 let (hi, ex) = match self.token {
2948 let e = self.parse_prefix_expr(None);
2949 let (span, e) = self.interpolated_or_expr_span(e)?;
2950 (lo.to(span), self.mk_unary(UnOp::Not, e))
2952 // Suggest `!` for bitwise negation when encountering a `~`
2955 let e = self.parse_prefix_expr(None);
2956 let (span, e) = self.interpolated_or_expr_span(e)?;
2957 let span_of_tilde = lo;
2958 let mut err = self.diagnostic()
2959 .struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator");
2960 err.span_suggestion_short_with_applicability(
2962 "use `!` to perform bitwise negation",
2964 Applicability::MachineApplicable
2967 (lo.to(span), self.mk_unary(UnOp::Not, e))
2969 token::BinOp(token::Minus) => {
2971 let e = self.parse_prefix_expr(None);
2972 let (span, e) = self.interpolated_or_expr_span(e)?;
2973 (lo.to(span), self.mk_unary(UnOp::Neg, e))
2975 token::BinOp(token::Star) => {
2977 let e = self.parse_prefix_expr(None);
2978 let (span, e) = self.interpolated_or_expr_span(e)?;
2979 (lo.to(span), self.mk_unary(UnOp::Deref, e))
2981 token::BinOp(token::And) | token::AndAnd => {
2983 let m = self.parse_mutability();
2984 let e = self.parse_prefix_expr(None);
2985 let (span, e) = self.interpolated_or_expr_span(e)?;
2986 (lo.to(span), ExprKind::AddrOf(m, e))
2988 token::Ident(..) if self.token.is_keyword(keywords::In) => {
2990 let place = self.parse_expr_res(
2991 Restrictions::NO_STRUCT_LITERAL,
2994 let blk = self.parse_block()?;
2995 let span = blk.span;
2996 let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new());
2997 (lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr))
2999 token::Ident(..) if self.token.is_keyword(keywords::Box) => {
3001 let e = self.parse_prefix_expr(None);
3002 let (span, e) = self.interpolated_or_expr_span(e)?;
3003 (lo.to(span), ExprKind::Box(e))
3005 token::Ident(..) if self.token.is_ident_named("not") => {
3006 // `not` is just an ordinary identifier in Rust-the-language,
3007 // but as `rustc`-the-compiler, we can issue clever diagnostics
3008 // for confused users who really want to say `!`
3009 let token_cannot_continue_expr = |t: &token::Token| match *t {
3010 // These tokens can start an expression after `!`, but
3011 // can't continue an expression after an ident
3012 token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw),
3013 token::Literal(..) | token::Pound => true,
3014 token::Interpolated(ref nt) => match nt.0 {
3015 token::NtIdent(..) | token::NtExpr(..) |
3016 token::NtBlock(..) | token::NtPath(..) => true,
3021 let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
3022 if cannot_continue_expr {
3024 // Emit the error ...
3025 let mut err = self.diagnostic()
3026 .struct_span_err(self.span,
3027 &format!("unexpected {} after identifier",
3028 self.this_token_descr()));
3029 // span the `not` plus trailing whitespace to avoid
3030 // trailing whitespace after the `!` in our suggestion
3031 let to_replace = self.sess.source_map()
3032 .span_until_non_whitespace(lo.to(self.span));
3033 err.span_suggestion_short_with_applicability(
3035 "use `!` to perform logical negation",
3037 Applicability::MachineApplicable
3040 // —and recover! (just as if we were in the block
3041 // for the `token::Not` arm)
3042 let e = self.parse_prefix_expr(None);
3043 let (span, e) = self.interpolated_or_expr_span(e)?;
3044 (lo.to(span), self.mk_unary(UnOp::Not, e))
3046 return self.parse_dot_or_call_expr(Some(attrs));
3049 _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
3051 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
3054 /// Parse an associative expression
3056 /// This parses an expression accounting for associativity and precedence of the operators in
3059 fn parse_assoc_expr(&mut self,
3060 already_parsed_attrs: Option<ThinVec<Attribute>>)
3061 -> PResult<'a, P<Expr>> {
3062 self.parse_assoc_expr_with(0, already_parsed_attrs.into())
3065 /// Parse an associative expression with operators of at least `min_prec` precedence
3066 fn parse_assoc_expr_with(&mut self,
3069 -> PResult<'a, P<Expr>> {
3070 let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
3073 let attrs = match lhs {
3074 LhsExpr::AttributesParsed(attrs) => Some(attrs),
3077 if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token) {
3078 return self.parse_prefix_range_expr(attrs);
3080 self.parse_prefix_expr(attrs)?
3084 if self.expr_is_complete(&lhs) {
3085 // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
3088 self.expected_tokens.push(TokenType::Operator);
3089 while let Some(op) = AssocOp::from_token(&self.token) {
3091 // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
3092 // it refers to. Interpolated identifiers are unwrapped early and never show up here
3093 // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
3094 // it as "interpolated", it doesn't change the answer for non-interpolated idents.
3095 let lhs_span = match (self.prev_token_kind, &lhs.node) {
3096 (PrevTokenKind::Interpolated, _) => self.prev_span,
3097 (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
3098 if path.segments.len() == 1 => self.prev_span,
3102 let cur_op_span = self.span;
3103 let restrictions = if op.is_assign_like() {
3104 self.restrictions & Restrictions::NO_STRUCT_LITERAL
3108 if op.precedence() < min_prec {
3111 // Check for deprecated `...` syntax
3112 if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
3113 self.err_dotdotdot_syntax(self.span);
3117 if op.is_comparison() {
3118 self.check_no_chained_comparison(&lhs, &op);
3121 if op == AssocOp::As {
3122 lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
3124 } else if op == AssocOp::Colon {
3125 lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) {
3128 err.span_label(self.span,
3129 "expecting a type here because of type ascription");
3130 let cm = self.sess.source_map();
3131 let cur_pos = cm.lookup_char_pos(self.span.lo());
3132 let op_pos = cm.lookup_char_pos(cur_op_span.hi());
3133 if cur_pos.line != op_pos.line {
3134 err.span_suggestion_with_applicability(
3136 "try using a semicolon",
3138 Applicability::MaybeIncorrect // speculative
3145 } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
3146 // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
3147 // generalise it to the Fixity::None code.
3149 // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
3150 // two variants are handled with `parse_prefix_range_expr` call above.
3151 let rhs = if self.is_at_start_of_range_notation_rhs() {
3152 Some(self.parse_assoc_expr_with(op.precedence() + 1,
3153 LhsExpr::NotYetParsed)?)
3157 let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
3162 let limits = if op == AssocOp::DotDot {
3163 RangeLimits::HalfOpen
3168 let r = self.mk_range(Some(lhs), rhs, limits)?;
3169 lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
3173 let rhs = match op.fixity() {
3174 Fixity::Right => self.with_res(
3175 restrictions - Restrictions::STMT_EXPR,
3177 this.parse_assoc_expr_with(op.precedence(),
3178 LhsExpr::NotYetParsed)
3180 Fixity::Left => self.with_res(
3181 restrictions - Restrictions::STMT_EXPR,
3183 this.parse_assoc_expr_with(op.precedence() + 1,
3184 LhsExpr::NotYetParsed)
3186 // We currently have no non-associative operators that are not handled above by
3187 // the special cases. The code is here only for future convenience.
3188 Fixity::None => self.with_res(
3189 restrictions - Restrictions::STMT_EXPR,
3191 this.parse_assoc_expr_with(op.precedence() + 1,
3192 LhsExpr::NotYetParsed)
3196 let span = lhs_span.to(rhs.span);
3198 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
3199 AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
3200 AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
3201 AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
3202 AssocOp::Greater | AssocOp::GreaterEqual => {
3203 let ast_op = op.to_ast_binop().unwrap();
3204 let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
3205 self.mk_expr(span, binary, ThinVec::new())
3208 self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
3209 AssocOp::ObsoleteInPlace =>
3210 self.mk_expr(span, ExprKind::ObsoleteInPlace(lhs, rhs), ThinVec::new()),
3211 AssocOp::AssignOp(k) => {
3213 token::Plus => BinOpKind::Add,
3214 token::Minus => BinOpKind::Sub,
3215 token::Star => BinOpKind::Mul,
3216 token::Slash => BinOpKind::Div,
3217 token::Percent => BinOpKind::Rem,
3218 token::Caret => BinOpKind::BitXor,
3219 token::And => BinOpKind::BitAnd,
3220 token::Or => BinOpKind::BitOr,
3221 token::Shl => BinOpKind::Shl,
3222 token::Shr => BinOpKind::Shr,
3224 let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
3225 self.mk_expr(span, aopexpr, ThinVec::new())
3227 AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
3228 self.bug("AssocOp should have been handled by special case")
3232 if op.fixity() == Fixity::None { break }
3237 fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
3238 expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
3239 -> PResult<'a, P<Expr>> {
3240 let mk_expr = |this: &mut Self, rhs: P<Ty>| {
3241 this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
3244 // Save the state of the parser before parsing type normally, in case there is a
3245 // LessThan comparison after this cast.
3246 let parser_snapshot_before_type = self.clone();
3247 match self.parse_ty_no_plus() {
3249 Ok(mk_expr(self, rhs))
3251 Err(mut type_err) => {
3252 // Rewind to before attempting to parse the type with generics, to recover
3253 // from situations like `x as usize < y` in which we first tried to parse
3254 // `usize < y` as a type with generic arguments.
3255 let parser_snapshot_after_type = self.clone();
3256 mem::replace(self, parser_snapshot_before_type);
3258 match self.parse_path(PathStyle::Expr) {
3260 let (op_noun, op_verb) = match self.token {
3261 token::Lt => ("comparison", "comparing"),
3262 token::BinOp(token::Shl) => ("shift", "shifting"),
3264 // We can end up here even without `<` being the next token, for
3265 // example because `parse_ty_no_plus` returns `Err` on keywords,
3266 // but `parse_path` returns `Ok` on them due to error recovery.
3267 // Return original error and parser state.
3268 mem::replace(self, parser_snapshot_after_type);
3269 return Err(type_err);
3273 // Successfully parsed the type path leaving a `<` yet to parse.
3276 // Report non-fatal diagnostics, keep `x as usize` as an expression
3277 // in AST and continue parsing.
3278 let msg = format!("`<` is interpreted as a start of generic \
3279 arguments for `{}`, not a {}", path, op_noun);
3280 let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
3281 err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span),
3282 "interpreted as generic arguments");
3283 err.span_label(self.span, format!("not interpreted as {}", op_noun));
3285 let expr = mk_expr(self, P(Ty {
3287 node: TyKind::Path(None, path),
3288 id: ast::DUMMY_NODE_ID
3291 let expr_str = self.sess.source_map().span_to_snippet(expr.span)
3292 .unwrap_or_else(|_| pprust::expr_to_string(&expr));
3293 err.span_suggestion_with_applicability(
3295 &format!("try {} the cast value", op_verb),
3296 format!("({})", expr_str),
3297 Applicability::MachineApplicable
3303 Err(mut path_err) => {
3304 // Couldn't parse as a path, return original error and parser state.
3306 mem::replace(self, parser_snapshot_after_type);
3314 /// Produce an error if comparison operators are chained (RFC #558).
3315 /// We only need to check lhs, not rhs, because all comparison ops
3316 /// have same precedence and are left-associative
3317 fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
3318 debug_assert!(outer_op.is_comparison(),
3319 "check_no_chained_comparison: {:?} is not comparison",
3322 ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
3323 // respan to include both operators
3324 let op_span = op.span.to(self.span);
3325 let mut err = self.diagnostic().struct_span_err(op_span,
3326 "chained comparison operators require parentheses");
3327 if op.node == BinOpKind::Lt &&
3328 *outer_op == AssocOp::Less || // Include `<` to provide this recommendation
3329 *outer_op == AssocOp::Greater // even in a case like the following:
3330 { // Foo<Bar<Baz<Qux, ()>>>
3332 "use `::<...>` instead of `<...>` if you meant to specify type arguments");
3333 err.help("or use `(...)` if you meant to specify fn arguments");
3341 /// Parse prefix-forms of range notation: `..expr`, `..`, `..=expr`
3342 fn parse_prefix_range_expr(&mut self,
3343 already_parsed_attrs: Option<ThinVec<Attribute>>)
3344 -> PResult<'a, P<Expr>> {
3345 // Check for deprecated `...` syntax
3346 if self.token == token::DotDotDot {
3347 self.err_dotdotdot_syntax(self.span);
3350 debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token),
3351 "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
3353 let tok = self.token.clone();
3354 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
3356 let mut hi = self.span;
3358 let opt_end = if self.is_at_start_of_range_notation_rhs() {
3359 // RHS must be parsed with more associativity than the dots.
3360 let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
3361 Some(self.parse_assoc_expr_with(next_prec,
3362 LhsExpr::NotYetParsed)
3370 let limits = if tok == token::DotDot {
3371 RangeLimits::HalfOpen
3376 let r = self.mk_range(None, opt_end, limits)?;
3377 Ok(self.mk_expr(lo.to(hi), r, attrs))
3380 fn is_at_start_of_range_notation_rhs(&self) -> bool {
3381 if self.token.can_begin_expr() {
3382 // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
3383 if self.token == token::OpenDelim(token::Brace) {
3384 return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
3392 /// Parse an 'if' or 'if let' expression ('if' token already eaten)
3393 fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3394 if self.check_keyword(keywords::Let) {
3395 return self.parse_if_let_expr(attrs);
3397 let lo = self.prev_span;
3398 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3400 // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
3401 // verify that the last statement is either an implicit return (no `;`) or an explicit
3402 // return. This won't catch blocks with an explicit `return`, but that would be caught by
3403 // the dead code lint.
3404 if self.eat_keyword(keywords::Else) || !cond.returns() {
3405 let sp = self.sess.source_map().next_point(lo);
3406 let mut err = self.diagnostic()
3407 .struct_span_err(sp, "missing condition for `if` statemement");
3408 err.span_label(sp, "expected if condition here");
3411 let not_block = self.token != token::OpenDelim(token::Brace);
3412 let thn = self.parse_block().map_err(|mut err| {
3414 err.span_label(lo, "this `if` statement has a condition, but no block");
3418 let mut els: Option<P<Expr>> = None;
3419 let mut hi = thn.span;
3420 if self.eat_keyword(keywords::Else) {
3421 let elexpr = self.parse_else_expr()?;
3425 Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
3428 /// Parse an 'if let' expression ('if' token already eaten)
3429 fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
3430 -> PResult<'a, P<Expr>> {
3431 let lo = self.prev_span;
3432 self.expect_keyword(keywords::Let)?;
3433 let pats = self.parse_pats()?;
3434 self.expect(&token::Eq)?;
3435 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3436 let thn = self.parse_block()?;
3437 let (hi, els) = if self.eat_keyword(keywords::Else) {
3438 let expr = self.parse_else_expr()?;
3439 (expr.span, Some(expr))
3443 Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
3446 // `move |args| expr`
3447 fn parse_lambda_expr(&mut self,
3448 attrs: ThinVec<Attribute>)
3449 -> PResult<'a, P<Expr>>
3452 let movability = if self.eat_keyword(keywords::Static) {
3457 let asyncness = if self.span.rust_2018() {
3458 self.parse_asyncness()
3462 let capture_clause = if self.eat_keyword(keywords::Move) {
3467 let decl = self.parse_fn_block_decl()?;
3468 let decl_hi = self.prev_span;
3469 let body = match decl.output {
3470 FunctionRetTy::Default(_) => {
3471 let restrictions = self.restrictions - Restrictions::STMT_EXPR;
3472 self.parse_expr_res(restrictions, None)?
3475 // If an explicit return type is given, require a
3476 // block to appear (RFC 968).
3477 let body_lo = self.span;
3478 self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
3484 ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
3488 // `else` token already eaten
3489 fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
3490 if self.eat_keyword(keywords::If) {
3491 return self.parse_if_expr(ThinVec::new());
3493 let blk = self.parse_block()?;
3494 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
3498 /// Parse a 'for' .. 'in' expression ('for' token already eaten)
3499 fn parse_for_expr(&mut self, opt_label: Option<Label>,
3501 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3502 // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
3504 let pat = self.parse_top_level_pat()?;
3505 if !self.eat_keyword(keywords::In) {
3506 let in_span = self.prev_span.between(self.span);
3507 let mut err = self.sess.span_diagnostic
3508 .struct_span_err(in_span, "missing `in` in `for` loop");
3509 err.span_suggestion_short_with_applicability(
3510 in_span, "try adding `in` here", " in ".into(),
3511 // has been misleading, at least in the past (closed Issue #48492)
3512 Applicability::MaybeIncorrect
3516 let in_span = self.prev_span;
3517 if self.eat_keyword(keywords::In) {
3518 // a common typo: `for _ in in bar {}`
3519 let mut err = self.sess.span_diagnostic.struct_span_err(
3521 "expected iterable, found keyword `in`",
3523 err.span_suggestion_short_with_applicability(
3524 in_span.until(self.prev_span),
3525 "remove the duplicated `in`",
3527 Applicability::MachineApplicable,
3529 err.note("if you meant to use emplacement syntax, it is obsolete (for now, anyway)");
3530 err.note("for more information on the status of emplacement syntax, see <\
3531 https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>");
3534 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3535 let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
3536 attrs.extend(iattrs);
3538 let hi = self.prev_span;
3539 Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
3542 /// Parse a 'while' or 'while let' expression ('while' token already eaten)
3543 fn parse_while_expr(&mut self, opt_label: Option<Label>,
3545 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3546 if self.token.is_keyword(keywords::Let) {
3547 return self.parse_while_let_expr(opt_label, span_lo, attrs);
3549 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3550 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3551 attrs.extend(iattrs);
3552 let span = span_lo.to(body.span);
3553 return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs));
3556 /// Parse a 'while let' expression ('while' token already eaten)
3557 fn parse_while_let_expr(&mut self, opt_label: Option<Label>,
3559 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3560 self.expect_keyword(keywords::Let)?;
3561 let pats = self.parse_pats()?;
3562 self.expect(&token::Eq)?;
3563 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3564 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3565 attrs.extend(iattrs);
3566 let span = span_lo.to(body.span);
3567 return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
3570 // parse `loop {...}`, `loop` token already eaten
3571 fn parse_loop_expr(&mut self, opt_label: Option<Label>,
3573 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3574 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3575 attrs.extend(iattrs);
3576 let span = span_lo.to(body.span);
3577 Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
3580 /// Parse an `async move {...}` expression
3581 pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>)
3582 -> PResult<'a, P<Expr>>
3584 let span_lo = self.span;
3585 self.expect_keyword(keywords::Async)?;
3586 let capture_clause = if self.eat_keyword(keywords::Move) {
3591 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3592 attrs.extend(iattrs);
3594 span_lo.to(body.span),
3595 ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs))
3598 /// Parse a `try {...}` expression (`try` token already eaten)
3599 fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
3600 -> PResult<'a, P<Expr>>
3602 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3603 attrs.extend(iattrs);
3604 Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
3607 // `match` token already eaten
3608 fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3609 let match_span = self.prev_span;
3610 let lo = self.prev_span;
3611 let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL,
3613 if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
3614 if self.token == token::Token::Semi {
3615 e.span_suggestion_short_with_applicability(
3617 "try removing this `match`",
3619 Applicability::MaybeIncorrect // speculative
3624 attrs.extend(self.parse_inner_attributes()?);
3626 let mut arms: Vec<Arm> = Vec::new();
3627 while self.token != token::CloseDelim(token::Brace) {
3628 match self.parse_arm() {
3629 Ok(arm) => arms.push(arm),
3631 // Recover by skipping to the end of the block.
3633 self.recover_stmt();
3634 let span = lo.to(self.span);
3635 if self.token == token::CloseDelim(token::Brace) {
3638 return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
3644 return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
3647 crate fn parse_arm(&mut self) -> PResult<'a, Arm> {
3648 maybe_whole!(self, NtArm, |x| x);
3650 let attrs = self.parse_outer_attributes()?;
3651 // Allow a '|' before the pats (RFC 1925)
3652 self.eat(&token::BinOp(token::Or));
3653 let pats = self.parse_pats()?;
3654 let guard = if self.eat_keyword(keywords::If) {
3655 Some(Guard::If(self.parse_expr()?))
3659 let arrow_span = self.span;
3660 self.expect(&token::FatArrow)?;
3661 let arm_start_span = self.span;
3663 let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
3664 .map_err(|mut err| {
3665 err.span_label(arrow_span, "while parsing the `match` arm starting here");
3669 let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
3670 && self.token != token::CloseDelim(token::Brace);
3673 let cm = self.sess.source_map();
3674 self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
3675 .map_err(|mut err| {
3676 match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
3677 (Ok(ref expr_lines), Ok(ref arm_start_lines))
3678 if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
3679 && expr_lines.lines.len() == 2
3680 && self.token == token::FatArrow => {
3681 // We check whether there's any trailing code in the parse span,
3682 // if there isn't, we very likely have the following:
3685 // | -- - missing comma
3691 // | parsed until here as `"y" & X`
3692 err.span_suggestion_short_with_applicability(
3693 cm.next_point(arm_start_span),
3694 "missing a comma here to end this `match` arm",
3696 Applicability::MachineApplicable
3700 err.span_label(arrow_span,
3701 "while parsing the `match` arm starting here");
3707 self.eat(&token::Comma);
3718 /// Parse an expression
3720 pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
3721 self.parse_expr_res(Restrictions::empty(), None)
3724 /// Evaluate the closure with restrictions in place.
3726 /// After the closure is evaluated, restrictions are reset.
3727 fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T
3728 where F: FnOnce(&mut Self) -> T
3730 let old = self.restrictions;
3731 self.restrictions = r;
3733 self.restrictions = old;
3738 /// Parse an expression, subject to the given restrictions
3740 fn parse_expr_res(&mut self, r: Restrictions,
3741 already_parsed_attrs: Option<ThinVec<Attribute>>)
3742 -> PResult<'a, P<Expr>> {
3743 self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
3746 /// Parse the RHS of a local variable declaration (e.g., '= 14;')
3747 fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
3748 if self.eat(&token::Eq) {
3749 Ok(Some(self.parse_expr()?))
3751 Ok(Some(self.parse_expr()?))
3757 /// Parse patterns, separated by '|' s
3758 fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3759 let mut pats = Vec::new();
3761 pats.push(self.parse_top_level_pat()?);
3763 if self.token == token::OrOr {
3764 let mut err = self.struct_span_err(self.span,
3765 "unexpected token `||` after pattern");
3766 err.span_suggestion_with_applicability(
3768 "use a single `|` to specify multiple patterns",
3770 Applicability::MachineApplicable
3774 } else if self.eat(&token::BinOp(token::Or)) {
3782 // Parses a parenthesized list of patterns like
3783 // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns:
3784 // - a vector of the patterns that were parsed
3785 // - an option indicating the index of the `..` element
3786 // - a boolean indicating whether a trailing comma was present.
3787 // Trailing commas are significant because (p) and (p,) are different patterns.
3788 fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3789 self.expect(&token::OpenDelim(token::Paren))?;
3790 let result = self.parse_pat_list()?;
3791 self.expect(&token::CloseDelim(token::Paren))?;
3795 fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3796 let mut fields = Vec::new();
3797 let mut ddpos = None;
3798 let mut trailing_comma = false;
3800 if self.eat(&token::DotDot) {
3801 if ddpos.is_none() {
3802 ddpos = Some(fields.len());
3804 // Emit a friendly error, ignore `..` and continue parsing
3805 self.span_err(self.prev_span,
3806 "`..` can only be used once per tuple or tuple struct pattern");
3808 } else if !self.check(&token::CloseDelim(token::Paren)) {
3809 fields.push(self.parse_pat(None)?);
3814 trailing_comma = self.eat(&token::Comma);
3815 if !trailing_comma {
3820 if ddpos == Some(fields.len()) && trailing_comma {
3821 // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
3822 self.span_err(self.prev_span, "trailing comma is not permitted after `..`");
3825 Ok((fields, ddpos, trailing_comma))
3828 fn parse_pat_vec_elements(
3830 ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3831 let mut before = Vec::new();
3832 let mut slice = None;
3833 let mut after = Vec::new();
3834 let mut first = true;
3835 let mut before_slice = true;
3837 while self.token != token::CloseDelim(token::Bracket) {
3841 self.expect(&token::Comma)?;
3843 if self.token == token::CloseDelim(token::Bracket)
3844 && (before_slice || !after.is_empty()) {
3850 if self.eat(&token::DotDot) {
3852 if self.check(&token::Comma) ||
3853 self.check(&token::CloseDelim(token::Bracket)) {
3854 slice = Some(P(Pat {
3855 id: ast::DUMMY_NODE_ID,
3856 node: PatKind::Wild,
3857 span: self.prev_span,
3859 before_slice = false;
3865 let subpat = self.parse_pat(None)?;
3866 if before_slice && self.eat(&token::DotDot) {
3867 slice = Some(subpat);
3868 before_slice = false;
3869 } else if before_slice {
3870 before.push(subpat);
3876 Ok((before, slice, after))
3882 attrs: Vec<Attribute>
3883 ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> {
3884 // Check if a colon exists one ahead. This means we're parsing a fieldname.
3886 let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3887 // Parsing a pattern of the form "fieldname: pat"
3888 let fieldname = self.parse_field_name()?;
3890 let pat = self.parse_pat(None)?;
3892 (pat, fieldname, false)
3894 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3895 let is_box = self.eat_keyword(keywords::Box);
3896 let boxed_span = self.span;
3897 let is_ref = self.eat_keyword(keywords::Ref);
3898 let is_mut = self.eat_keyword(keywords::Mut);
3899 let fieldname = self.parse_ident()?;
3900 hi = self.prev_span;
3902 let bind_type = match (is_ref, is_mut) {
3903 (true, true) => BindingMode::ByRef(Mutability::Mutable),
3904 (true, false) => BindingMode::ByRef(Mutability::Immutable),
3905 (false, true) => BindingMode::ByValue(Mutability::Mutable),
3906 (false, false) => BindingMode::ByValue(Mutability::Immutable),
3908 let fieldpat = P(Pat {
3909 id: ast::DUMMY_NODE_ID,
3910 node: PatKind::Ident(bind_type, fieldname, None),
3911 span: boxed_span.to(hi),
3914 let subpat = if is_box {
3916 id: ast::DUMMY_NODE_ID,
3917 node: PatKind::Box(fieldpat),
3923 (subpat, fieldname, true)
3926 Ok(source_map::Spanned {
3928 node: ast::FieldPat {
3932 attrs: attrs.into(),
3937 /// Parse the fields of a struct-like pattern
3938 fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> {
3939 let mut fields = Vec::new();
3940 let mut etc = false;
3941 let mut ate_comma = true;
3942 let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
3943 let mut etc_span = None;
3945 while self.token != token::CloseDelim(token::Brace) {
3946 let attrs = self.parse_outer_attributes()?;
3949 // check that a comma comes after every field
3951 let err = self.struct_span_err(self.prev_span, "expected `,`");
3952 if let Some(mut delayed) = delayed_err {
3959 if self.check(&token::DotDot) || self.token == token::DotDotDot {
3961 let mut etc_sp = self.span;
3963 if self.token == token::DotDotDot { // Issue #46718
3964 // Accept `...` as if it were `..` to avoid further errors
3965 let mut err = self.struct_span_err(self.span,
3966 "expected field pattern, found `...`");
3967 err.span_suggestion_with_applicability(
3969 "to omit remaining fields, use one fewer `.`",
3971 Applicability::MachineApplicable
3975 self.bump(); // `..` || `...`
3977 if self.token == token::CloseDelim(token::Brace) {
3978 etc_span = Some(etc_sp);
3981 let token_str = self.this_token_descr();
3982 let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
3984 err.span_label(self.span, "expected `}`");
3985 let mut comma_sp = None;
3986 if self.token == token::Comma { // Issue #49257
3987 etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span));
3988 err.span_label(etc_sp,
3989 "`..` must be at the end and cannot have a trailing comma");
3990 comma_sp = Some(self.span);
3995 etc_span = Some(etc_sp.until(self.span));
3996 if self.token == token::CloseDelim(token::Brace) {
3997 // If the struct looks otherwise well formed, recover and continue.
3998 if let Some(sp) = comma_sp {
3999 err.span_suggestion_short_with_applicability(
4001 "remove this comma",
4003 Applicability::MachineApplicable,
4008 } else if self.token.is_ident() && ate_comma {
4009 // Accept fields coming after `..,`.
4010 // This way we avoid "pattern missing fields" errors afterwards.
4011 // We delay this error until the end in order to have a span for a
4013 if let Some(mut delayed_err) = delayed_err {
4017 delayed_err = Some(err);
4020 if let Some(mut err) = delayed_err {
4027 fields.push(match self.parse_pat_field(lo, attrs) {
4030 if let Some(mut delayed_err) = delayed_err {
4036 ate_comma = self.eat(&token::Comma);
4039 if let Some(mut err) = delayed_err {
4040 if let Some(etc_span) = etc_span {
4041 err.multipart_suggestion(
4042 "move the `..` to the end of the field list",
4044 (etc_span, String::new()),
4045 (self.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
4051 return Ok((fields, etc));
4054 fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
4055 if self.token.is_path_start() {
4057 let (qself, path) = if self.eat_lt() {
4058 // Parse a qualified path
4059 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4062 // Parse an unqualified path
4063 (None, self.parse_path(PathStyle::Expr)?)
4065 let hi = self.prev_span;
4066 Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
4068 self.parse_literal_maybe_minus()
4072 // helper function to decide whether to parse as ident binding or to try to do
4073 // something more complex like range patterns
4074 fn parse_as_ident(&mut self) -> bool {
4075 self.look_ahead(1, |t| match *t {
4076 token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
4077 token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false),
4078 // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the
4079 // range pattern branch
4080 token::DotDot => None,
4082 }).unwrap_or_else(|| self.look_ahead(2, |t| match *t {
4083 token::Comma | token::CloseDelim(token::Bracket) => true,
4088 /// A wrapper around `parse_pat` with some special error handling for the
4089 /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
4090 /// to subpatterns within such).
4091 fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
4092 let pat = self.parse_pat(None)?;
4093 if self.token == token::Comma {
4094 // An unexpected comma after a top-level pattern is a clue that the
4095 // user (perhaps more accustomed to some other language) forgot the
4096 // parentheses in what should have been a tuple pattern; return a
4097 // suggestion-enhanced error here rather than choking on the comma
4099 let comma_span = self.span;
4101 if let Err(mut err) = self.parse_pat_list() {
4102 // We didn't expect this to work anyway; we just wanted
4103 // to advance to the end of the comma-sequence so we know
4104 // the span to suggest parenthesizing
4107 let seq_span = pat.span.to(self.prev_span);
4108 let mut err = self.struct_span_err(comma_span,
4109 "unexpected `,` in pattern");
4110 if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) {
4111 err.span_suggestion_with_applicability(
4113 "try adding parentheses",
4114 format!("({})", seq_snippet),
4115 Applicability::MachineApplicable
4123 /// Parse a pattern.
4124 pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
4125 self.parse_pat_with_range_pat(true, expected)
4128 /// Parse a pattern, with a setting whether modern range patterns e.g., `a..=b`, `a..b` are
4130 fn parse_pat_with_range_pat(
4132 allow_range_pat: bool,
4133 expected: Option<&'static str>,
4134 ) -> PResult<'a, P<Pat>> {
4135 maybe_whole!(self, NtPat, |x| x);
4140 token::BinOp(token::And) | token::AndAnd => {
4141 // Parse &pat / &mut pat
4143 let mutbl = self.parse_mutability();
4144 if let token::Lifetime(ident) = self.token {
4145 let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern",
4147 err.span_label(self.span, "unexpected lifetime");
4150 let subpat = self.parse_pat_with_range_pat(false, expected)?;
4151 pat = PatKind::Ref(subpat, mutbl);
4153 token::OpenDelim(token::Paren) => {
4154 // Parse (pat,pat,pat,...) as tuple pattern
4155 let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?;
4156 pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma {
4157 PatKind::Paren(fields.into_iter().nth(0).unwrap())
4159 PatKind::Tuple(fields, ddpos)
4162 token::OpenDelim(token::Bracket) => {
4163 // Parse [pat,pat,...] as slice pattern
4165 let (before, slice, after) = self.parse_pat_vec_elements()?;
4166 self.expect(&token::CloseDelim(token::Bracket))?;
4167 pat = PatKind::Slice(before, slice, after);
4169 // At this point, token != &, &&, (, [
4170 _ => if self.eat_keyword(keywords::Underscore) {
4172 pat = PatKind::Wild;
4173 } else if self.eat_keyword(keywords::Mut) {
4174 // Parse mut ident @ pat / mut ref ident @ pat
4175 let mutref_span = self.prev_span.to(self.span);
4176 let binding_mode = if self.eat_keyword(keywords::Ref) {
4178 .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
4179 .span_suggestion_with_applicability(
4181 "try switching the order",
4183 Applicability::MachineApplicable
4185 BindingMode::ByRef(Mutability::Mutable)
4187 BindingMode::ByValue(Mutability::Mutable)
4189 pat = self.parse_pat_ident(binding_mode)?;
4190 } else if self.eat_keyword(keywords::Ref) {
4191 // Parse ref ident @ pat / ref mut ident @ pat
4192 let mutbl = self.parse_mutability();
4193 pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
4194 } else if self.eat_keyword(keywords::Box) {
4196 let subpat = self.parse_pat_with_range_pat(false, None)?;
4197 pat = PatKind::Box(subpat);
4198 } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
4199 self.parse_as_ident() {
4200 // Parse ident @ pat
4201 // This can give false positives and parse nullary enums,
4202 // they are dealt with later in resolve
4203 let binding_mode = BindingMode::ByValue(Mutability::Immutable);
4204 pat = self.parse_pat_ident(binding_mode)?;
4205 } else if self.token.is_path_start() {
4206 // Parse pattern starting with a path
4207 let (qself, path) = if self.eat_lt() {
4208 // Parse a qualified path
4209 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4212 // Parse an unqualified path
4213 (None, self.parse_path(PathStyle::Expr)?)
4216 token::Not if qself.is_none() => {
4217 // Parse macro invocation
4219 let (delim, tts) = self.expect_delimited_token_tree()?;
4220 let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim });
4221 pat = PatKind::Mac(mac);
4223 token::DotDotDot | token::DotDotEq | token::DotDot => {
4224 let end_kind = match self.token {
4225 token::DotDot => RangeEnd::Excluded,
4226 token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot),
4227 token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq),
4228 _ => panic!("can only parse `..`/`...`/`..=` for ranges \
4231 let op_span = self.span;
4233 let span = lo.to(self.prev_span);
4234 let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
4236 let end = self.parse_pat_range_end()?;
4237 let op = Spanned { span: op_span, node: end_kind };
4238 pat = PatKind::Range(begin, end, op);
4240 token::OpenDelim(token::Brace) => {
4241 if qself.is_some() {
4242 let msg = "unexpected `{` after qualified path";
4243 let mut err = self.fatal(msg);
4244 err.span_label(self.span, msg);
4247 // Parse struct pattern
4249 let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
4251 self.recover_stmt();
4255 pat = PatKind::Struct(path, fields, etc);
4257 token::OpenDelim(token::Paren) => {
4258 if qself.is_some() {
4259 let msg = "unexpected `(` after qualified path";
4260 let mut err = self.fatal(msg);
4261 err.span_label(self.span, msg);
4264 // Parse tuple struct or enum pattern
4265 let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?;
4266 pat = PatKind::TupleStruct(path, fields, ddpos)
4268 _ => pat = PatKind::Path(qself, path),
4271 // Try to parse everything else as literal with optional minus
4272 match self.parse_literal_maybe_minus() {
4274 let op_span = self.span;
4275 if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
4276 self.check(&token::DotDotDot) {
4277 let end_kind = if self.eat(&token::DotDotDot) {
4278 RangeEnd::Included(RangeSyntax::DotDotDot)
4279 } else if self.eat(&token::DotDotEq) {
4280 RangeEnd::Included(RangeSyntax::DotDotEq)
4281 } else if self.eat(&token::DotDot) {
4284 panic!("impossible case: we already matched \
4285 on a range-operator token")
4287 let end = self.parse_pat_range_end()?;
4288 let op = Spanned { span: op_span, node: end_kind };
4289 pat = PatKind::Range(begin, end, op);
4291 pat = PatKind::Lit(begin);
4295 self.cancel(&mut err);
4296 let expected = expected.unwrap_or("pattern");
4298 "expected {}, found {}",
4300 self.this_token_descr(),
4302 let mut err = self.fatal(&msg);
4303 err.span_label(self.span, format!("expected {}", expected));
4310 let pat = Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID };
4311 let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
4313 if !allow_range_pat {
4316 _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
4318 PatKind::Range(..) => {
4319 let mut err = self.struct_span_err(
4321 "the range pattern here has ambiguous interpretation",
4323 err.span_suggestion_with_applicability(
4325 "add parentheses to clarify the precedence",
4326 format!("({})", pprust::pat_to_string(&pat)),
4327 // "ambiguous interpretation" implies that we have to be guessing
4328 Applicability::MaybeIncorrect
4339 /// Parse ident or ident @ pat
4340 /// used by the copy foo and ref foo patterns to give a good
4341 /// error message when parsing mistakes like ref foo(a,b)
4342 fn parse_pat_ident(&mut self,
4343 binding_mode: ast::BindingMode)
4344 -> PResult<'a, PatKind> {
4345 let ident = self.parse_ident()?;
4346 let sub = if self.eat(&token::At) {
4347 Some(self.parse_pat(Some("binding pattern"))?)
4352 // just to be friendly, if they write something like
4354 // we end up here with ( as the current token. This shortly
4355 // leads to a parse error. Note that if there is no explicit
4356 // binding mode then we do not end up here, because the lookahead
4357 // will direct us over to parse_enum_variant()
4358 if self.token == token::OpenDelim(token::Paren) {
4359 return Err(self.span_fatal(
4361 "expected identifier, found enum pattern"))
4364 Ok(PatKind::Ident(binding_mode, ident, sub))
4367 /// Parse a local variable declaration
4368 fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
4369 let lo = self.prev_span;
4370 let pat = self.parse_top_level_pat()?;
4372 let (err, ty) = if self.eat(&token::Colon) {
4373 // Save the state of the parser before parsing type normally, in case there is a `:`
4374 // instead of an `=` typo.
4375 let parser_snapshot_before_type = self.clone();
4376 let colon_sp = self.prev_span;
4377 match self.parse_ty() {
4378 Ok(ty) => (None, Some(ty)),
4380 // Rewind to before attempting to parse the type and continue parsing
4381 let parser_snapshot_after_type = self.clone();
4382 mem::replace(self, parser_snapshot_before_type);
4384 let snippet = self.sess.source_map().span_to_snippet(pat.span).unwrap();
4385 err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
4386 (Some((parser_snapshot_after_type, colon_sp, err)), None)
4392 let init = match (self.parse_initializer(err.is_some()), err) {
4393 (Ok(init), None) => { // init parsed, ty parsed
4396 (Ok(init), Some((_, colon_sp, mut err))) => { // init parsed, ty error
4397 // Could parse the type as if it were the initializer, it is likely there was a
4398 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
4399 err.span_suggestion_short_with_applicability(
4401 "use `=` if you meant to assign",
4403 Applicability::MachineApplicable
4406 // As this was parsed successfully, continue as if the code has been fixed for the
4407 // rest of the file. It will still fail due to the emitted error, but we avoid
4411 (Err(mut init_err), Some((snapshot, _, ty_err))) => { // init error, ty error
4413 // Couldn't parse the type nor the initializer, only raise the type error and
4414 // return to the parser state before parsing the type as the initializer.
4415 // let x: <parse_error>;
4416 mem::replace(self, snapshot);
4419 (Err(err), None) => { // init error, ty parsed
4420 // Couldn't parse the initializer and we're not attempting to recover a failed
4421 // parse of the type, return the error.
4425 let hi = if self.token == token::Semi {
4434 id: ast::DUMMY_NODE_ID,
4440 /// Parse a structure field
4441 fn parse_name_and_ty(&mut self,
4444 attrs: Vec<Attribute>)
4445 -> PResult<'a, StructField> {
4446 let name = self.parse_ident()?;
4447 self.expect(&token::Colon)?;
4448 let ty = self.parse_ty()?;
4450 span: lo.to(self.prev_span),
4453 id: ast::DUMMY_NODE_ID,
4459 /// Emit an expected item after attributes error.
4460 fn expected_item_err(&self, attrs: &[Attribute]) {
4461 let message = match attrs.last() {
4462 Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
4463 _ => "expected item after attributes",
4466 self.span_err(self.prev_span, message);
4469 /// Parse a statement. This stops just before trailing semicolons on everything but items.
4470 /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
4471 pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
4472 Ok(self.parse_stmt_(true))
4475 // Eat tokens until we can be relatively sure we reached the end of the
4476 // statement. This is something of a best-effort heuristic.
4478 // We terminate when we find an unmatched `}` (without consuming it).
4479 fn recover_stmt(&mut self) {
4480 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
4483 // If `break_on_semi` is `Break`, then we will stop consuming tokens after
4484 // finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
4485 // approximate - it can mean we break too early due to macros, but that
4486 // should only lead to sub-optimal recovery, not inaccurate parsing).
4488 // If `break_on_block` is `Break`, then we will stop consuming tokens
4489 // after finding (and consuming) a brace-delimited block.
4490 fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) {
4491 let mut brace_depth = 0;
4492 let mut bracket_depth = 0;
4493 let mut in_block = false;
4494 debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
4495 break_on_semi, break_on_block);
4497 debug!("recover_stmt_ loop {:?}", self.token);
4499 token::OpenDelim(token::DelimToken::Brace) => {
4502 if break_on_block == BlockMode::Break &&
4504 bracket_depth == 0 {
4508 token::OpenDelim(token::DelimToken::Bracket) => {
4512 token::CloseDelim(token::DelimToken::Brace) => {
4513 if brace_depth == 0 {
4514 debug!("recover_stmt_ return - close delim {:?}", self.token);
4519 if in_block && bracket_depth == 0 && brace_depth == 0 {
4520 debug!("recover_stmt_ return - block end {:?}", self.token);
4524 token::CloseDelim(token::DelimToken::Bracket) => {
4526 if bracket_depth < 0 {
4532 debug!("recover_stmt_ return - Eof");
4537 if break_on_semi == SemiColonMode::Break &&
4539 bracket_depth == 0 {
4540 debug!("recover_stmt_ return - Semi");
4551 fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
4552 self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
4554 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4559 fn is_async_block(&mut self) -> bool {
4560 self.token.is_keyword(keywords::Async) &&
4563 self.look_ahead(1, |t| t.is_keyword(keywords::Move)) &&
4564 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
4566 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
4571 fn is_do_catch_block(&mut self) -> bool {
4572 self.token.is_keyword(keywords::Do) &&
4573 self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) &&
4574 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
4575 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4578 fn is_try_block(&mut self) -> bool {
4579 self.token.is_keyword(keywords::Try) &&
4580 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
4581 self.span.rust_2018() &&
4582 // prevent `while try {} {}`, `if try {} {} else {}`, etc.
4583 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4586 fn is_union_item(&self) -> bool {
4587 self.token.is_keyword(keywords::Union) &&
4588 self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
4591 fn is_crate_vis(&self) -> bool {
4592 self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
4595 fn is_extern_non_path(&self) -> bool {
4596 self.token.is_keyword(keywords::Extern) && self.look_ahead(1, |t| t != &token::ModSep)
4599 fn is_existential_type_decl(&self) -> bool {
4600 self.token.is_keyword(keywords::Existential) &&
4601 self.look_ahead(1, |t| t.is_keyword(keywords::Type))
4604 fn is_auto_trait_item(&mut self) -> bool {
4606 (self.token.is_keyword(keywords::Auto)
4607 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
4608 || // unsafe auto trait
4609 (self.token.is_keyword(keywords::Unsafe) &&
4610 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) &&
4611 self.look_ahead(2, |t| t.is_keyword(keywords::Trait)))
4614 fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span)
4615 -> PResult<'a, Option<P<Item>>> {
4616 let token_lo = self.span;
4617 let (ident, def) = match self.token {
4618 token::Ident(ident, false) if ident.name == keywords::Macro.name() => {
4620 let ident = self.parse_ident()?;
4621 let tokens = if self.check(&token::OpenDelim(token::Brace)) {
4622 match self.parse_token_tree() {
4623 TokenTree::Delimited(_, _, tts) => tts.stream(),
4624 _ => unreachable!(),
4626 } else if self.check(&token::OpenDelim(token::Paren)) {
4627 let args = self.parse_token_tree();
4628 let body = if self.check(&token::OpenDelim(token::Brace)) {
4629 self.parse_token_tree()
4634 TokenStream::new(vec![
4636 TokenTree::Token(token_lo.to(self.prev_span), token::FatArrow).into(),
4644 (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
4646 token::Ident(ident, _) if ident.name == "macro_rules" &&
4647 self.look_ahead(1, |t| *t == token::Not) => {
4648 let prev_span = self.prev_span;
4649 self.complain_if_pub_macro(&vis.node, prev_span);
4653 let ident = self.parse_ident()?;
4654 let (delim, tokens) = self.expect_delimited_token_tree()?;
4655 if delim != MacDelimiter::Brace {
4656 if !self.eat(&token::Semi) {
4657 let msg = "macros that expand to items must either \
4658 be surrounded with braces or followed by a semicolon";
4659 self.span_err(self.prev_span, msg);
4663 (ident, ast::MacroDef { tokens: tokens, legacy: true })
4665 _ => return Ok(None),
4668 let span = lo.to(self.prev_span);
4669 Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
4672 fn parse_stmt_without_recovery(&mut self,
4673 macro_legacy_warnings: bool)
4674 -> PResult<'a, Option<Stmt>> {
4675 maybe_whole!(self, NtStmt, |x| Some(x));
4677 let attrs = self.parse_outer_attributes()?;
4680 Ok(Some(if self.eat_keyword(keywords::Let) {
4682 id: ast::DUMMY_NODE_ID,
4683 node: StmtKind::Local(self.parse_local(attrs.into())?),
4684 span: lo.to(self.prev_span),
4686 } else if let Some(macro_def) = self.eat_macro_def(
4688 &source_map::respan(lo, VisibilityKind::Inherited),
4692 id: ast::DUMMY_NODE_ID,
4693 node: StmtKind::Item(macro_def),
4694 span: lo.to(self.prev_span),
4696 // Starts like a simple path, being careful to avoid contextual keywords
4697 // such as a union items, item with `crate` visibility or auto trait items.
4698 // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
4699 // like a path (1 token), but it fact not a path.
4700 // `union::b::c` - path, `union U { ... }` - not a path.
4701 // `crate::b::c` - path, `crate struct S;` - not a path.
4702 // `extern::b::c` - path, `extern crate c;` - not a path.
4703 } else if self.token.is_path_start() &&
4704 !self.token.is_qpath_start() &&
4705 !self.is_union_item() &&
4706 !self.is_crate_vis() &&
4707 !self.is_extern_non_path() &&
4708 !self.is_existential_type_decl() &&
4709 !self.is_auto_trait_item() {
4710 let pth = self.parse_path(PathStyle::Expr)?;
4712 if !self.eat(&token::Not) {
4713 let expr = if self.check(&token::OpenDelim(token::Brace)) {
4714 self.parse_struct_expr(lo, pth, ThinVec::new())?
4716 let hi = self.prev_span;
4717 self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), ThinVec::new())
4720 let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
4721 let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
4722 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
4725 return Ok(Some(Stmt {
4726 id: ast::DUMMY_NODE_ID,
4727 node: StmtKind::Expr(expr),
4728 span: lo.to(self.prev_span),
4732 // it's a macro invocation
4733 let id = match self.token {
4734 token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier
4735 _ => self.parse_ident()?,
4738 // check that we're pointing at delimiters (need to check
4739 // again after the `if`, because of `parse_ident`
4740 // consuming more tokens).
4742 token::OpenDelim(_) => {}
4744 // we only expect an ident if we didn't parse one
4746 let ident_str = if id.name == keywords::Invalid.name() {
4751 let tok_str = self.this_token_descr();
4752 let mut err = self.fatal(&format!("expected {}`(` or `{{`, found {}",
4755 err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str));
4760 let (delim, tts) = self.expect_delimited_token_tree()?;
4761 let hi = self.prev_span;
4763 let style = if delim == MacDelimiter::Brace {
4764 MacStmtStyle::Braces
4766 MacStmtStyle::NoBraces
4769 if id.name == keywords::Invalid.name() {
4770 let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim });
4771 let node = if delim == MacDelimiter::Brace ||
4772 self.token == token::Semi || self.token == token::Eof {
4773 StmtKind::Mac(P((mac, style, attrs.into())))
4775 // We used to incorrectly stop parsing macro-expanded statements here.
4776 // If the next token will be an error anyway but could have parsed with the
4777 // earlier behavior, stop parsing here and emit a warning to avoid breakage.
4778 else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token {
4779 // These can continue an expression, so we can't stop parsing and warn.
4780 token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
4781 token::BinOp(token::Minus) | token::BinOp(token::Star) |
4782 token::BinOp(token::And) | token::BinOp(token::Or) |
4783 token::AndAnd | token::OrOr |
4784 token::DotDot | token::DotDotDot | token::DotDotEq => false,
4787 self.warn_missing_semicolon();
4788 StmtKind::Mac(P((mac, style, attrs.into())))
4790 let e = self.mk_mac_expr(lo.to(hi), mac.node, ThinVec::new());
4791 let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
4792 let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
4796 id: ast::DUMMY_NODE_ID,
4801 // if it has a special ident, it's definitely an item
4803 // Require a semicolon or braces.
4804 if style != MacStmtStyle::Braces {
4805 if !self.eat(&token::Semi) {
4806 self.span_err(self.prev_span,
4807 "macros that expand to items must \
4808 either be surrounded with braces or \
4809 followed by a semicolon");
4812 let span = lo.to(hi);
4814 id: ast::DUMMY_NODE_ID,
4816 node: StmtKind::Item({
4818 span, id /*id is good here*/,
4819 ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })),
4820 respan(lo, VisibilityKind::Inherited),
4826 // FIXME: Bad copy of attrs
4827 let old_directory_ownership =
4828 mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
4829 let item = self.parse_item_(attrs.clone(), false, true)?;
4830 self.directory.ownership = old_directory_ownership;
4834 id: ast::DUMMY_NODE_ID,
4835 span: lo.to(i.span),
4836 node: StmtKind::Item(i),
4839 let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
4840 if !attrs.is_empty() {
4841 if s.prev_token_kind == PrevTokenKind::DocComment {
4842 s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
4843 } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
4844 s.span_err(s.span, "expected statement after outer attribute");
4849 // Do not attempt to parse an expression if we're done here.
4850 if self.token == token::Semi {
4851 unused_attrs(&attrs, self);
4856 if self.token == token::CloseDelim(token::Brace) {
4857 unused_attrs(&attrs, self);
4861 // Remainder are line-expr stmts.
4862 let e = self.parse_expr_res(
4863 Restrictions::STMT_EXPR, Some(attrs.into()))?;
4865 id: ast::DUMMY_NODE_ID,
4866 span: lo.to(e.span),
4867 node: StmtKind::Expr(e),
4874 /// Is this expression a successfully-parsed statement?
4875 fn expr_is_complete(&mut self, e: &Expr) -> bool {
4876 self.restrictions.contains(Restrictions::STMT_EXPR) &&
4877 !classify::expr_requires_semi_to_be_stmt(e)
4880 /// Parse a block. No inner attrs are allowed.
4881 pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
4882 maybe_whole!(self, NtBlock, |x| x);
4886 if !self.eat(&token::OpenDelim(token::Brace)) {
4888 let tok = self.this_token_descr();
4889 let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok));
4890 let do_not_suggest_help =
4891 self.token.is_keyword(keywords::In) || self.token == token::Colon;
4893 if self.token.is_ident_named("and") {
4894 e.span_suggestion_short_with_applicability(
4896 "use `&&` instead of `and` for the boolean operator",
4898 Applicability::MaybeIncorrect,
4901 if self.token.is_ident_named("or") {
4902 e.span_suggestion_short_with_applicability(
4904 "use `||` instead of `or` for the boolean operator",
4906 Applicability::MaybeIncorrect,
4910 // Check to see if the user has written something like
4915 // Which is valid in other languages, but not Rust.
4916 match self.parse_stmt_without_recovery(false) {
4918 if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
4919 || do_not_suggest_help {
4920 // if the next token is an open brace (e.g., `if a b {`), the place-
4921 // inside-a-block suggestion would be more likely wrong than right
4922 e.span_label(sp, "expected `{`");
4925 let mut stmt_span = stmt.span;
4926 // expand the span to include the semicolon, if it exists
4927 if self.eat(&token::Semi) {
4928 stmt_span = stmt_span.with_hi(self.prev_span.hi());
4930 let sugg = pprust::to_string(|s| {
4931 use print::pprust::{PrintState, INDENT_UNIT};
4932 s.ibox(INDENT_UNIT)?;
4934 s.print_stmt(&stmt)?;
4935 s.bclose_maybe_open(stmt.span, INDENT_UNIT, false)
4937 e.span_suggestion_with_applicability(
4939 "try placing this code inside a block",
4941 // speculative, has been misleading in the past (closed Issue #46836)
4942 Applicability::MaybeIncorrect
4946 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4947 self.cancel(&mut e);
4951 e.span_label(sp, "expected `{`");
4955 self.parse_block_tail(lo, BlockCheckMode::Default)
4958 /// Parse a block. Inner attrs are allowed.
4959 fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
4960 maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
4963 self.expect(&token::OpenDelim(token::Brace))?;
4964 Ok((self.parse_inner_attributes()?,
4965 self.parse_block_tail(lo, BlockCheckMode::Default)?))
4968 /// Parse the rest of a block expression or function body
4969 /// Precondition: already parsed the '{'.
4970 fn parse_block_tail(&mut self, lo: Span, s: BlockCheckMode) -> PResult<'a, P<Block>> {
4971 let mut stmts = vec![];
4972 while !self.eat(&token::CloseDelim(token::Brace)) {
4973 let stmt = match self.parse_full_stmt(false) {
4976 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
4978 id: ast::DUMMY_NODE_ID,
4979 node: StmtKind::Expr(DummyResult::raw_expr(self.span, true)),
4985 if let Some(stmt) = stmt {
4987 } else if self.token == token::Eof {
4990 // Found only `;` or `}`.
4996 id: ast::DUMMY_NODE_ID,
4998 span: lo.to(self.prev_span),
5002 /// Parse a statement, including the trailing semicolon.
5003 crate fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
5004 // skip looking for a trailing semicolon when we have an interpolated statement
5005 maybe_whole!(self, NtStmt, |x| Some(x));
5007 let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
5009 None => return Ok(None),
5013 StmtKind::Expr(ref expr) if self.token != token::Eof => {
5014 // expression without semicolon
5015 if classify::expr_requires_semi_to_be_stmt(expr) {
5016 // Just check for errors and recover; do not eat semicolon yet.
5018 self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
5021 self.recover_stmt();
5025 StmtKind::Local(..) => {
5026 // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
5027 if macro_legacy_warnings && self.token != token::Semi {
5028 self.warn_missing_semicolon();
5030 self.expect_one_of(&[], &[token::Semi])?;
5036 if self.eat(&token::Semi) {
5037 stmt = stmt.add_trailing_semicolon();
5040 stmt.span = stmt.span.with_hi(self.prev_span.hi());
5044 fn warn_missing_semicolon(&self) {
5045 self.diagnostic().struct_span_warn(self.span, {
5046 &format!("expected `;`, found {}", self.this_token_descr())
5048 "This was erroneously allowed and will become a hard error in a future release"
5052 fn err_dotdotdot_syntax(&self, span: Span) {
5053 self.diagnostic().struct_span_err(span, {
5054 "unexpected token: `...`"
5055 }).span_suggestion_with_applicability(
5056 span, "use `..` for an exclusive range", "..".to_owned(),
5057 Applicability::MaybeIncorrect
5058 ).span_suggestion_with_applicability(
5059 span, "or `..=` for an inclusive range", "..=".to_owned(),
5060 Applicability::MaybeIncorrect
5064 // Parse bounds of a type parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5065 // BOUND = TY_BOUND | LT_BOUND
5066 // LT_BOUND = LIFETIME (e.g., `'a`)
5067 // TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
5068 // TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
5069 fn parse_generic_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, GenericBounds> {
5070 let mut bounds = Vec::new();
5072 // This needs to be synchronized with `Token::can_begin_bound`.
5073 let is_bound_start = self.check_path() || self.check_lifetime() ||
5074 self.check(&token::Question) ||
5075 self.check_keyword(keywords::For) ||
5076 self.check(&token::OpenDelim(token::Paren));
5079 let has_parens = self.eat(&token::OpenDelim(token::Paren));
5080 let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
5081 if self.token.is_lifetime() {
5082 if let Some(question_span) = question {
5083 self.span_err(question_span,
5084 "`?` may only modify trait bounds, not lifetime bounds");
5086 bounds.push(GenericBound::Outlives(self.expect_lifetime()));
5088 self.expect(&token::CloseDelim(token::Paren))?;
5089 self.span_err(self.prev_span,
5090 "parenthesized lifetime bounds are not supported");
5093 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5094 let path = self.parse_path(PathStyle::Type)?;
5096 self.expect(&token::CloseDelim(token::Paren))?;
5098 let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span));
5099 let modifier = if question.is_some() {
5100 TraitBoundModifier::Maybe
5102 TraitBoundModifier::None
5104 bounds.push(GenericBound::Trait(poly_trait, modifier));
5110 if !allow_plus || !self.eat_plus() {
5118 fn parse_generic_bounds(&mut self) -> PResult<'a, GenericBounds> {
5119 self.parse_generic_bounds_common(true)
5122 // Parse bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
5123 // BOUND = LT_BOUND (e.g., `'a`)
5124 fn parse_lt_param_bounds(&mut self) -> GenericBounds {
5125 let mut lifetimes = Vec::new();
5126 while self.check_lifetime() {
5127 lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
5129 if !self.eat_plus() {
5136 /// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
5137 fn parse_ty_param(&mut self,
5138 preceding_attrs: Vec<Attribute>)
5139 -> PResult<'a, GenericParam> {
5140 let ident = self.parse_ident()?;
5142 // Parse optional colon and param bounds.
5143 let bounds = if self.eat(&token::Colon) {
5144 self.parse_generic_bounds()?
5149 let default = if self.eat(&token::Eq) {
5150 Some(self.parse_ty()?)
5157 id: ast::DUMMY_NODE_ID,
5158 attrs: preceding_attrs.into(),
5160 kind: GenericParamKind::Type {
5166 /// Parses the following grammar:
5167 /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
5168 fn parse_trait_item_assoc_ty(&mut self)
5169 -> PResult<'a, (Ident, TraitItemKind, ast::Generics)> {
5170 let ident = self.parse_ident()?;
5171 let mut generics = self.parse_generics()?;
5173 // Parse optional colon and param bounds.
5174 let bounds = if self.eat(&token::Colon) {
5175 self.parse_generic_bounds()?
5179 generics.where_clause = self.parse_where_clause()?;
5181 let default = if self.eat(&token::Eq) {
5182 Some(self.parse_ty()?)
5186 self.expect(&token::Semi)?;
5188 Ok((ident, TraitItemKind::Type(bounds, default), generics))
5191 /// Parses (possibly empty) list of lifetime and type parameters, possibly including
5192 /// trailing comma and erroneous trailing attributes.
5193 crate fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
5194 let mut lifetimes = Vec::new();
5195 let mut params = Vec::new();
5196 let mut seen_ty_param: Option<Span> = None;
5197 let mut last_comma_span = None;
5198 let mut bad_lifetime_pos = vec![];
5199 let mut suggestions = vec![];
5201 let attrs = self.parse_outer_attributes()?;
5202 if self.check_lifetime() {
5203 let lifetime = self.expect_lifetime();
5204 // Parse lifetime parameter.
5205 let bounds = if self.eat(&token::Colon) {
5206 self.parse_lt_param_bounds()
5210 lifetimes.push(ast::GenericParam {
5211 ident: lifetime.ident,
5213 attrs: attrs.into(),
5215 kind: ast::GenericParamKind::Lifetime,
5217 if let Some(sp) = seen_ty_param {
5218 let param_span = self.prev_span;
5219 let ate_comma = self.eat(&token::Comma);
5220 let remove_sp = if ate_comma {
5221 param_span.until(self.span)
5223 last_comma_span.unwrap_or(param_span).to(param_span)
5225 bad_lifetime_pos.push(param_span);
5227 if let Ok(snippet) = self.sess.source_map().span_to_snippet(param_span) {
5228 suggestions.push((remove_sp, String::new()));
5229 suggestions.push((sp.shrink_to_lo(), format!("{}, ", snippet)));
5232 last_comma_span = Some(self.prev_span);
5236 } else if self.check_ident() {
5237 // Parse type parameter.
5238 params.push(self.parse_ty_param(attrs)?);
5239 if seen_ty_param.is_none() {
5240 seen_ty_param = Some(self.prev_span);
5243 // Check for trailing attributes and stop parsing.
5244 if !attrs.is_empty() {
5245 let param_kind = if seen_ty_param.is_some() { "type" } else { "lifetime" };
5246 self.span_err(attrs[0].span,
5247 &format!("trailing attribute after {} parameters", param_kind));
5252 if !self.eat(&token::Comma) {
5255 last_comma_span = Some(self.prev_span);
5257 if !bad_lifetime_pos.is_empty() {
5258 let mut err = self.struct_span_err(
5260 "lifetime parameters must be declared prior to type parameters",
5262 if !suggestions.is_empty() {
5263 err.multipart_suggestion_with_applicability(
5264 "move the lifetime parameter prior to the first type parameter",
5266 Applicability::MachineApplicable,
5271 lifetimes.extend(params); // ensure the correct order of lifetimes and type params
5275 /// Parse a set of optional generic type parameter declarations. Where
5276 /// clauses are not parsed here, and must be added later via
5277 /// `parse_where_clause()`.
5279 /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
5280 /// | ( < lifetimes , typaramseq ( , )? > )
5281 /// where typaramseq = ( typaram ) | ( typaram , typaramseq )
5282 fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
5283 maybe_whole!(self, NtGenerics, |x| x);
5285 let span_lo = self.span;
5287 let params = self.parse_generic_params()?;
5291 where_clause: WhereClause {
5292 id: ast::DUMMY_NODE_ID,
5293 predicates: Vec::new(),
5294 span: syntax_pos::DUMMY_SP,
5296 span: span_lo.to(self.prev_span),
5299 Ok(ast::Generics::default())
5303 /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
5304 /// possibly including trailing comma.
5305 fn parse_generic_args(&mut self)
5306 -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
5307 let mut args = Vec::new();
5308 let mut bindings = Vec::new();
5309 let mut seen_type = false;
5310 let mut seen_binding = false;
5312 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5313 // Parse lifetime argument.
5314 args.push(GenericArg::Lifetime(self.expect_lifetime()));
5315 if seen_type || seen_binding {
5316 self.span_err(self.prev_span,
5317 "lifetime parameters must be declared prior to type parameters");
5319 } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
5320 // Parse associated type binding.
5322 let ident = self.parse_ident()?;
5324 let ty = self.parse_ty()?;
5325 bindings.push(TypeBinding {
5326 id: ast::DUMMY_NODE_ID,
5329 span: lo.to(self.prev_span),
5331 seen_binding = true;
5332 } else if self.check_type() {
5333 // Parse type argument.
5334 let ty_param = self.parse_ty()?;
5336 self.span_err(ty_param.span,
5337 "type parameters must be declared prior to associated type bindings");
5339 args.push(GenericArg::Type(ty_param));
5345 if !self.eat(&token::Comma) {
5349 Ok((args, bindings))
5352 /// Parses an optional `where` clause and places it in `generics`.
5354 /// ```ignore (only-for-syntax-highlight)
5355 /// where T : Trait<U, V> + 'b, 'a : 'b
5357 fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
5358 maybe_whole!(self, NtWhereClause, |x| x);
5360 let mut where_clause = WhereClause {
5361 id: ast::DUMMY_NODE_ID,
5362 predicates: Vec::new(),
5363 span: syntax_pos::DUMMY_SP,
5366 if !self.eat_keyword(keywords::Where) {
5367 return Ok(where_clause);
5369 let lo = self.prev_span;
5371 // We are considering adding generics to the `where` keyword as an alternative higher-rank
5372 // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
5373 // change we parse those generics now, but report an error.
5374 if self.choose_generics_over_qpath() {
5375 let generics = self.parse_generics()?;
5376 self.span_err(generics.span,
5377 "generic parameters on `where` clauses are reserved for future use");
5382 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5383 let lifetime = self.expect_lifetime();
5384 // Bounds starting with a colon are mandatory, but possibly empty.
5385 self.expect(&token::Colon)?;
5386 let bounds = self.parse_lt_param_bounds();
5387 where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
5388 ast::WhereRegionPredicate {
5389 span: lo.to(self.prev_span),
5394 } else if self.check_type() {
5395 // Parse optional `for<'a, 'b>`.
5396 // This `for` is parsed greedily and applies to the whole predicate,
5397 // the bounded type can have its own `for` applying only to it.
5398 // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/>
5399 // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/>
5400 // Example 3: for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /*ok*/, 'b /*not ok*/>
5401 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5403 // Parse type with mandatory colon and (possibly empty) bounds,
5404 // or with mandatory equality sign and the second type.
5405 let ty = self.parse_ty()?;
5406 if self.eat(&token::Colon) {
5407 let bounds = self.parse_generic_bounds()?;
5408 where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
5409 ast::WhereBoundPredicate {
5410 span: lo.to(self.prev_span),
5411 bound_generic_params: lifetime_defs,
5416 // FIXME: Decide what should be used here, `=` or `==`.
5417 // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
5418 } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
5419 let rhs_ty = self.parse_ty()?;
5420 where_clause.predicates.push(ast::WherePredicate::EqPredicate(
5421 ast::WhereEqPredicate {
5422 span: lo.to(self.prev_span),
5425 id: ast::DUMMY_NODE_ID,
5429 return self.unexpected();
5435 if !self.eat(&token::Comma) {
5440 where_clause.span = lo.to(self.prev_span);
5444 fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
5445 -> PResult<'a, (Vec<Arg> , bool)> {
5446 self.expect(&token::OpenDelim(token::Paren))?;
5449 let mut variadic = false;
5450 let args: Vec<Option<Arg>> =
5451 self.parse_seq_to_before_end(
5452 &token::CloseDelim(token::Paren),
5453 SeqSep::trailing_allowed(token::Comma),
5455 if p.token == token::DotDotDot {
5459 if p.token != token::CloseDelim(token::Paren) {
5462 "`...` must be last in argument list for variadic function");
5466 let span = p.prev_span;
5467 if p.token == token::CloseDelim(token::Paren) {
5468 // continue parsing to present any further errors
5471 "only foreign functions are allowed to be variadic"
5473 Ok(Some(dummy_arg(span)))
5475 // this function definition looks beyond recovery, stop parsing
5477 "only foreign functions are allowed to be variadic");
5482 match p.parse_arg_general(named_args, false) {
5483 Ok(arg) => Ok(Some(arg)),
5486 let lo = p.prev_span;
5487 // Skip every token until next possible arg or end.
5488 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
5489 // Create a placeholder argument for proper arg count (#34264).
5490 let span = lo.to(p.prev_span);
5491 Ok(Some(dummy_arg(span)))
5498 self.eat(&token::CloseDelim(token::Paren));
5500 let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
5502 if variadic && args.is_empty() {
5504 "variadic function must be declared with at least one named argument");
5507 Ok((args, variadic))
5510 /// Parse the argument list and result type of a function declaration
5511 fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
5513 let (args, variadic) = self.parse_fn_args(true, allow_variadic)?;
5514 let ret_ty = self.parse_ret_ty(true)?;
5523 /// Returns the parsed optional self argument and whether a self shortcut was used.
5524 fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
5525 let expect_ident = |this: &mut Self| match this.token {
5526 // Preserve hygienic context.
5527 token::Ident(ident, _) =>
5528 { let span = this.span; this.bump(); Ident::new(ident.name, span) }
5531 let isolated_self = |this: &mut Self, n| {
5532 this.look_ahead(n, |t| t.is_keyword(keywords::SelfLower)) &&
5533 this.look_ahead(n + 1, |t| t != &token::ModSep)
5536 // Parse optional self parameter of a method.
5537 // Only a limited set of initial token sequences is considered self parameters, anything
5538 // else is parsed as a normal function parameter list, so some lookahead is required.
5539 let eself_lo = self.span;
5540 let (eself, eself_ident, eself_hi) = match self.token {
5541 token::BinOp(token::And) => {
5547 (if isolated_self(self, 1) {
5549 SelfKind::Region(None, Mutability::Immutable)
5550 } else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
5551 isolated_self(self, 2) {
5554 SelfKind::Region(None, Mutability::Mutable)
5555 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5556 isolated_self(self, 2) {
5558 let lt = self.expect_lifetime();
5559 SelfKind::Region(Some(lt), Mutability::Immutable)
5560 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5561 self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
5562 isolated_self(self, 3) {
5564 let lt = self.expect_lifetime();
5566 SelfKind::Region(Some(lt), Mutability::Mutable)
5569 }, expect_ident(self), self.prev_span)
5571 token::BinOp(token::Star) => {
5576 // Emit special error for `self` cases.
5577 (if isolated_self(self, 1) {
5579 self.span_err(self.span, "cannot pass `self` by raw pointer");
5580 SelfKind::Value(Mutability::Immutable)
5581 } else if self.look_ahead(1, |t| t.is_mutability()) &&
5582 isolated_self(self, 2) {
5585 self.span_err(self.span, "cannot pass `self` by raw pointer");
5586 SelfKind::Value(Mutability::Immutable)
5589 }, expect_ident(self), self.prev_span)
5591 token::Ident(..) => {
5592 if isolated_self(self, 0) {
5595 let eself_ident = expect_ident(self);
5596 let eself_hi = self.prev_span;
5597 (if self.eat(&token::Colon) {
5598 let ty = self.parse_ty()?;
5599 SelfKind::Explicit(ty, Mutability::Immutable)
5601 SelfKind::Value(Mutability::Immutable)
5602 }, eself_ident, eself_hi)
5603 } else if self.token.is_keyword(keywords::Mut) &&
5604 isolated_self(self, 1) {
5608 let eself_ident = expect_ident(self);
5609 let eself_hi = self.prev_span;
5610 (if self.eat(&token::Colon) {
5611 let ty = self.parse_ty()?;
5612 SelfKind::Explicit(ty, Mutability::Mutable)
5614 SelfKind::Value(Mutability::Mutable)
5615 }, eself_ident, eself_hi)
5620 _ => return Ok(None),
5623 let eself = source_map::respan(eself_lo.to(eself_hi), eself);
5624 Ok(Some(Arg::from_self(eself, eself_ident)))
5627 /// Parse the parameter list and result type of a function that may have a `self` parameter.
5628 fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>>
5629 where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
5631 self.expect(&token::OpenDelim(token::Paren))?;
5633 // Parse optional self argument
5634 let self_arg = self.parse_self_arg()?;
5636 // Parse the rest of the function parameter list.
5637 let sep = SeqSep::trailing_allowed(token::Comma);
5638 let fn_inputs = if let Some(self_arg) = self_arg {
5639 if self.check(&token::CloseDelim(token::Paren)) {
5641 } else if self.eat(&token::Comma) {
5642 let mut fn_inputs = vec![self_arg];
5643 fn_inputs.append(&mut self.parse_seq_to_before_end(
5644 &token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5648 return self.unexpected();
5651 self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5654 // Parse closing paren and return type.
5655 self.expect(&token::CloseDelim(token::Paren))?;
5658 output: self.parse_ret_ty(true)?,
5663 // parse the |arg, arg| header on a lambda
5664 fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
5665 let inputs_captures = {
5666 if self.eat(&token::OrOr) {
5669 self.expect(&token::BinOp(token::Or))?;
5670 let args = self.parse_seq_to_before_tokens(
5671 &[&token::BinOp(token::Or), &token::OrOr],
5672 SeqSep::trailing_allowed(token::Comma),
5673 TokenExpectType::NoExpect,
5674 |p| p.parse_fn_block_arg()
5680 let output = self.parse_ret_ty(true)?;
5683 inputs: inputs_captures,
5689 /// Parse the name and optional generic types of a function header.
5690 fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
5691 let id = self.parse_ident()?;
5692 let generics = self.parse_generics()?;
5696 fn mk_item(&mut self, span: Span, ident: Ident, node: ItemKind, vis: Visibility,
5697 attrs: Vec<Attribute>) -> P<Item> {
5701 id: ast::DUMMY_NODE_ID,
5709 /// Parse an item-position function declaration.
5710 fn parse_item_fn(&mut self,
5713 constness: Spanned<Constness>,
5715 -> PResult<'a, ItemInfo> {
5716 let (ident, mut generics) = self.parse_fn_header()?;
5717 let decl = self.parse_fn_decl(false)?;
5718 generics.where_clause = self.parse_where_clause()?;
5719 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5720 let header = FnHeader { unsafety, asyncness, constness, abi };
5721 Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
5724 /// true if we are looking at `const ID`, false for things like `const fn` etc
5725 fn is_const_item(&mut self) -> bool {
5726 self.token.is_keyword(keywords::Const) &&
5727 !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
5728 !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
5731 /// parses all the "front matter" for a `fn` declaration, up to
5732 /// and including the `fn` keyword:
5736 /// - `const unsafe fn`
5739 fn parse_fn_front_matter(&mut self)
5747 let is_const_fn = self.eat_keyword(keywords::Const);
5748 let const_span = self.prev_span;
5749 let unsafety = self.parse_unsafety();
5750 let asyncness = self.parse_asyncness();
5751 let (constness, unsafety, abi) = if is_const_fn {
5752 (respan(const_span, Constness::Const), unsafety, Abi::Rust)
5754 let abi = if self.eat_keyword(keywords::Extern) {
5755 self.parse_opt_abi()?.unwrap_or(Abi::C)
5759 (respan(self.prev_span, Constness::NotConst), unsafety, abi)
5761 self.expect_keyword(keywords::Fn)?;
5762 Ok((constness, unsafety, asyncness, abi))
5765 /// Parse an impl item.
5766 pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
5767 maybe_whole!(self, NtImplItem, |x| x);
5768 let attrs = self.parse_outer_attributes()?;
5769 let (mut item, tokens) = self.collect_tokens(|this| {
5770 this.parse_impl_item_(at_end, attrs)
5773 // See `parse_item` for why this clause is here.
5774 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
5775 item.tokens = Some(tokens);
5780 fn parse_impl_item_(&mut self,
5782 mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> {
5784 let vis = self.parse_visibility(false)?;
5785 let defaultness = self.parse_defaultness();
5786 let (name, node, generics) = if let Some(type_) = self.eat_type() {
5787 let (name, alias, generics) = type_?;
5788 let kind = match alias {
5789 AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ),
5790 AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds),
5792 (name, kind, generics)
5793 } else if self.is_const_item() {
5794 // This parses the grammar:
5795 // ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
5796 self.expect_keyword(keywords::Const)?;
5797 let name = self.parse_ident()?;
5798 self.expect(&token::Colon)?;
5799 let typ = self.parse_ty()?;
5800 self.expect(&token::Eq)?;
5801 let expr = self.parse_expr()?;
5802 self.expect(&token::Semi)?;
5803 (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default())
5805 let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?;
5806 attrs.extend(inner_attrs);
5807 (name, node, generics)
5811 id: ast::DUMMY_NODE_ID,
5812 span: lo.to(self.prev_span),
5823 fn complain_if_pub_macro(&mut self, vis: &VisibilityKind, sp: Span) {
5825 VisibilityKind::Inherited => {}
5827 let is_macro_rules: bool = match self.token {
5828 token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"),
5831 let mut err = if is_macro_rules {
5832 let mut err = self.diagnostic()
5833 .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
5834 err.span_suggestion_with_applicability(
5836 "try exporting the macro",
5837 "#[macro_export]".to_owned(),
5838 Applicability::MaybeIncorrect // speculative
5842 let mut err = self.diagnostic()
5843 .struct_span_err(sp, "can't qualify macro invocation with `pub`");
5844 err.help("try adjusting the macro to put `pub` inside the invocation");
5852 fn missing_assoc_item_kind_err(&mut self, item_type: &str, prev_span: Span)
5853 -> DiagnosticBuilder<'a>
5855 let expected_kinds = if item_type == "extern" {
5856 "missing `fn`, `type`, or `static`"
5858 "missing `fn`, `type`, or `const`"
5861 // Given this code `path(`, it seems like this is not
5862 // setting the visibility of a macro invocation, but rather
5863 // a mistyped method declaration.
5864 // Create a diagnostic pointing out that `fn` is missing.
5866 // x | pub path(&self) {
5867 // | ^ missing `fn`, `type`, or `const`
5869 // ^^ `sp` below will point to this
5870 let sp = prev_span.between(self.prev_span);
5871 let mut err = self.diagnostic().struct_span_err(
5873 &format!("{} for {}-item declaration",
5874 expected_kinds, item_type));
5875 err.span_label(sp, expected_kinds);
5879 /// Parse a method or a macro invocation in a trait impl.
5880 fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
5881 -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics,
5882 ast::ImplItemKind)> {
5883 // code copied from parse_macro_use_or_failure... abstraction!
5884 if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
5886 Ok((keywords::Invalid.ident(), vec![], ast::Generics::default(),
5887 ast::ImplItemKind::Macro(mac)))
5889 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
5890 let ident = self.parse_ident()?;
5891 let mut generics = self.parse_generics()?;
5892 let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
5893 generics.where_clause = self.parse_where_clause()?;
5895 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5896 let header = ast::FnHeader { abi, unsafety, constness, asyncness };
5897 Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
5898 ast::MethodSig { header, decl },
5904 /// Parse `trait Foo { ... }` or `trait Foo = Bar;`
5905 fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5906 let ident = self.parse_ident()?;
5907 let mut tps = self.parse_generics()?;
5909 // Parse optional colon and supertrait bounds.
5910 let bounds = if self.eat(&token::Colon) {
5911 self.parse_generic_bounds()?
5916 if self.eat(&token::Eq) {
5917 // it's a trait alias
5918 let bounds = self.parse_generic_bounds()?;
5919 tps.where_clause = self.parse_where_clause()?;
5920 self.expect(&token::Semi)?;
5921 if unsafety != Unsafety::Normal {
5922 self.span_err(self.prev_span, "trait aliases cannot be unsafe");
5924 Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
5926 // it's a normal trait
5927 tps.where_clause = self.parse_where_clause()?;
5928 self.expect(&token::OpenDelim(token::Brace))?;
5929 let mut trait_items = vec![];
5930 while !self.eat(&token::CloseDelim(token::Brace)) {
5931 let mut at_end = false;
5932 match self.parse_trait_item(&mut at_end) {
5933 Ok(item) => trait_items.push(item),
5937 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5942 Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
5946 fn choose_generics_over_qpath(&self) -> bool {
5947 // There's an ambiguity between generic parameters and qualified paths in impls.
5948 // If we see `<` it may start both, so we have to inspect some following tokens.
5949 // The following combinations can only start generics,
5950 // but not qualified paths (with one exception):
5951 // `<` `>` - empty generic parameters
5952 // `<` `#` - generic parameters with attributes
5953 // `<` (LIFETIME|IDENT) `>` - single generic parameter
5954 // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
5955 // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
5956 // `<` (LIFETIME|IDENT) `=` - generic parameter with a default
5957 // The only truly ambiguous case is
5958 // `<` IDENT `>` `::` IDENT ...
5959 // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
5960 // because this is what almost always expected in practice, qualified paths in impls
5961 // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
5962 self.token == token::Lt &&
5963 (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
5964 self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
5965 self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
5966 t == &token::Colon || t == &token::Eq))
5969 fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
5970 self.expect(&token::OpenDelim(token::Brace))?;
5971 let attrs = self.parse_inner_attributes()?;
5973 let mut impl_items = Vec::new();
5974 while !self.eat(&token::CloseDelim(token::Brace)) {
5975 let mut at_end = false;
5976 match self.parse_impl_item(&mut at_end) {
5977 Ok(impl_item) => impl_items.push(impl_item),
5981 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5986 Ok((impl_items, attrs))
5989 /// Parses an implementation item, `impl` keyword is already parsed.
5990 /// impl<'a, T> TYPE { /* impl items */ }
5991 /// impl<'a, T> TRAIT for TYPE { /* impl items */ }
5992 /// impl<'a, T> !TRAIT for TYPE { /* impl items */ }
5993 /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
5994 /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
5995 /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
5996 fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
5997 -> PResult<'a, ItemInfo> {
5998 // First, parse generic parameters if necessary.
5999 let mut generics = if self.choose_generics_over_qpath() {
6000 self.parse_generics()?
6002 ast::Generics::default()
6005 // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
6006 let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
6008 ast::ImplPolarity::Negative
6010 ast::ImplPolarity::Positive
6013 // Parse both types and traits as a type, then reinterpret if necessary.
6014 let ty_first = self.parse_ty()?;
6016 // If `for` is missing we try to recover.
6017 let has_for = self.eat_keyword(keywords::For);
6018 let missing_for_span = self.prev_span.between(self.span);
6020 let ty_second = if self.token == token::DotDot {
6021 // We need to report this error after `cfg` expansion for compatibility reasons
6022 self.bump(); // `..`, do not add it to expected tokens
6023 Some(P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID }))
6024 } else if has_for || self.token.can_begin_type() {
6025 Some(self.parse_ty()?)
6030 generics.where_clause = self.parse_where_clause()?;
6032 let (impl_items, attrs) = self.parse_impl_body()?;
6034 let item_kind = match ty_second {
6035 Some(ty_second) => {
6036 // impl Trait for Type
6038 self.span_err(missing_for_span, "missing `for` in a trait impl");
6041 let ty_first = ty_first.into_inner();
6042 let path = match ty_first.node {
6043 // This notably includes paths passed through `ty` macro fragments (#46438).
6044 TyKind::Path(None, path) => path,
6046 self.span_err(ty_first.span, "expected a trait, found type");
6047 ast::Path::from_ident(Ident::new(keywords::Invalid.name(), ty_first.span))
6050 let trait_ref = TraitRef { path, ref_id: ty_first.id };
6052 ItemKind::Impl(unsafety, polarity, defaultness,
6053 generics, Some(trait_ref), ty_second, impl_items)
6057 ItemKind::Impl(unsafety, polarity, defaultness,
6058 generics, None, ty_first, impl_items)
6062 Ok((keywords::Invalid.ident(), item_kind, Some(attrs)))
6065 fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
6066 if self.eat_keyword(keywords::For) {
6068 let params = self.parse_generic_params()?;
6070 // We rely on AST validation to rule out invalid cases: There must not be type
6071 // parameters, and the lifetime parameters must not have bounds.
6078 /// Parse struct Foo { ... }
6079 fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
6080 let class_name = self.parse_ident()?;
6082 let mut generics = self.parse_generics()?;
6084 // There is a special case worth noting here, as reported in issue #17904.
6085 // If we are parsing a tuple struct it is the case that the where clause
6086 // should follow the field list. Like so:
6088 // struct Foo<T>(T) where T: Copy;
6090 // If we are parsing a normal record-style struct it is the case
6091 // that the where clause comes before the body, and after the generics.
6092 // So if we look ahead and see a brace or a where-clause we begin
6093 // parsing a record style struct.
6095 // Otherwise if we look ahead and see a paren we parse a tuple-style
6098 let vdata = if self.token.is_keyword(keywords::Where) {
6099 generics.where_clause = self.parse_where_clause()?;
6100 if self.eat(&token::Semi) {
6101 // If we see a: `struct Foo<T> where T: Copy;` style decl.
6102 VariantData::Unit(ast::DUMMY_NODE_ID)
6104 // If we see: `struct Foo<T> where T: Copy { ... }`
6105 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6107 // No `where` so: `struct Foo<T>;`
6108 } else if self.eat(&token::Semi) {
6109 VariantData::Unit(ast::DUMMY_NODE_ID)
6110 // Record-style struct definition
6111 } else if self.token == token::OpenDelim(token::Brace) {
6112 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6113 // Tuple-style struct definition with optional where-clause.
6114 } else if self.token == token::OpenDelim(token::Paren) {
6115 let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID);
6116 generics.where_clause = self.parse_where_clause()?;
6117 self.expect(&token::Semi)?;
6120 let token_str = self.this_token_descr();
6121 let mut err = self.fatal(&format!(
6122 "expected `where`, `{{`, `(`, or `;` after struct name, found {}",
6125 err.span_label(self.span, "expected `where`, `{`, `(`, or `;` after struct name");
6129 Ok((class_name, ItemKind::Struct(vdata, generics), None))
6132 /// Parse union Foo { ... }
6133 fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
6134 let class_name = self.parse_ident()?;
6136 let mut generics = self.parse_generics()?;
6138 let vdata = if self.token.is_keyword(keywords::Where) {
6139 generics.where_clause = self.parse_where_clause()?;
6140 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6141 } else if self.token == token::OpenDelim(token::Brace) {
6142 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
6144 let token_str = self.this_token_descr();
6145 let mut err = self.fatal(&format!(
6146 "expected `where` or `{{` after union name, found {}", token_str));
6147 err.span_label(self.span, "expected `where` or `{` after union name");
6151 Ok((class_name, ItemKind::Union(vdata, generics), None))
6154 fn consume_block(&mut self, delim: token::DelimToken) {
6155 let mut brace_depth = 0;
6157 if self.eat(&token::OpenDelim(delim)) {
6159 } else if self.eat(&token::CloseDelim(delim)) {
6160 if brace_depth == 0 {
6166 } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
6174 fn parse_record_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6175 let mut fields = Vec::new();
6176 if self.eat(&token::OpenDelim(token::Brace)) {
6177 while self.token != token::CloseDelim(token::Brace) {
6178 let field = self.parse_struct_decl_field().map_err(|e| {
6179 self.recover_stmt();
6183 Ok(field) => fields.push(field),
6189 self.eat(&token::CloseDelim(token::Brace));
6191 let token_str = self.this_token_descr();
6192 let mut err = self.fatal(&format!(
6193 "expected `where`, or `{{` after struct name, found {}", token_str));
6194 err.span_label(self.span, "expected `where`, or `{` after struct name");
6201 fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6202 // This is the case where we find `struct Foo<T>(T) where T: Copy;`
6203 // Unit like structs are handled in parse_item_struct function
6204 let fields = self.parse_unspanned_seq(
6205 &token::OpenDelim(token::Paren),
6206 &token::CloseDelim(token::Paren),
6207 SeqSep::trailing_allowed(token::Comma),
6209 let attrs = p.parse_outer_attributes()?;
6211 let vis = p.parse_visibility(true)?;
6212 let ty = p.parse_ty()?;
6214 span: lo.to(ty.span),
6217 id: ast::DUMMY_NODE_ID,
6226 /// Parse a structure field declaration
6227 fn parse_single_struct_field(&mut self,
6230 attrs: Vec<Attribute> )
6231 -> PResult<'a, StructField> {
6232 let mut seen_comma: bool = false;
6233 let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
6234 if self.token == token::Comma {
6241 token::CloseDelim(token::Brace) => {}
6242 token::DocComment(_) => {
6243 let previous_span = self.prev_span;
6244 let mut err = self.span_fatal_err(self.span, Error::UselessDocComment);
6245 self.bump(); // consume the doc comment
6246 let comma_after_doc_seen = self.eat(&token::Comma);
6247 // `seen_comma` is always false, because we are inside doc block
6248 // condition is here to make code more readable
6249 if seen_comma == false && comma_after_doc_seen == true {
6252 if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
6255 if seen_comma == false {
6256 let sp = self.sess.source_map().next_point(previous_span);
6257 err.span_suggestion_with_applicability(
6259 "missing comma here",
6261 Applicability::MachineApplicable
6268 let sp = self.sess.source_map().next_point(self.prev_span);
6269 let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}",
6270 self.this_token_descr()));
6271 if self.token.is_ident() {
6272 // This is likely another field; emit the diagnostic and keep going
6273 err.span_suggestion_with_applicability(
6275 "try adding a comma",
6277 Applicability::MachineApplicable,
6288 /// Parse an element of a struct definition
6289 fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
6290 let attrs = self.parse_outer_attributes()?;
6292 let vis = self.parse_visibility(false)?;
6293 self.parse_single_struct_field(lo, vis, attrs)
6296 /// Parse `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
6297 /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
6298 /// If the following element can't be a tuple (i.e., it's a function definition,
6299 /// it's not a tuple struct field) and the contents within the parens
6300 /// isn't valid, emit a proper diagnostic.
6301 pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
6302 maybe_whole!(self, NtVis, |x| x);
6304 self.expected_tokens.push(TokenType::Keyword(keywords::Crate));
6305 if self.is_crate_vis() {
6306 self.bump(); // `crate`
6307 return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
6310 if !self.eat_keyword(keywords::Pub) {
6311 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
6312 // keyword to grab a span from for inherited visibility; an empty span at the
6313 // beginning of the current token would seem to be the "Schelling span".
6314 return Ok(respan(self.span.shrink_to_lo(), VisibilityKind::Inherited))
6316 let lo = self.prev_span;
6318 if self.check(&token::OpenDelim(token::Paren)) {
6319 // We don't `self.bump()` the `(` yet because this might be a struct definition where
6320 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
6321 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
6322 // by the following tokens.
6323 if self.look_ahead(1, |t| t.is_keyword(keywords::Crate)) {
6326 self.bump(); // `crate`
6327 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6329 lo.to(self.prev_span),
6330 VisibilityKind::Crate(CrateSugar::PubCrate),
6333 } else if self.look_ahead(1, |t| t.is_keyword(keywords::In)) {
6336 self.bump(); // `in`
6337 let path = self.parse_path(PathStyle::Mod)?; // `path`
6338 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6339 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6341 id: ast::DUMMY_NODE_ID,
6344 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
6345 self.look_ahead(1, |t| t.is_keyword(keywords::Super) ||
6346 t.is_keyword(keywords::SelfLower))
6348 // `pub(self)` or `pub(super)`
6350 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
6351 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6352 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6354 id: ast::DUMMY_NODE_ID,
6357 } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct
6358 // `pub(something) fn ...` or `struct X { pub(something) y: Z }`
6360 let msg = "incorrect visibility restriction";
6361 let suggestion = r##"some possible visibility restrictions are:
6362 `pub(crate)`: visible only on the current crate
6363 `pub(super)`: visible only in the current module's parent
6364 `pub(in path::to::module)`: visible only on the specified path"##;
6365 let path = self.parse_path(PathStyle::Mod)?;
6366 let sp = self.prev_span;
6367 let help_msg = format!("make this visible only to module `{}` with `in`", path);
6368 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6369 let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg);
6370 err.help(suggestion);
6371 err.span_suggestion_with_applicability(
6372 sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable
6374 err.emit(); // emit diagnostic, but continue with public visibility
6378 Ok(respan(lo, VisibilityKind::Public))
6381 /// Parse defaultness: `default` or nothing.
6382 fn parse_defaultness(&mut self) -> Defaultness {
6383 // `pub` is included for better error messages
6384 if self.check_keyword(keywords::Default) &&
6385 self.look_ahead(1, |t| t.is_keyword(keywords::Impl) ||
6386 t.is_keyword(keywords::Const) ||
6387 t.is_keyword(keywords::Fn) ||
6388 t.is_keyword(keywords::Unsafe) ||
6389 t.is_keyword(keywords::Extern) ||
6390 t.is_keyword(keywords::Type) ||
6391 t.is_keyword(keywords::Pub)) {
6392 self.bump(); // `default`
6393 Defaultness::Default
6399 /// Given a termination token, parse all of the items in a module
6400 fn parse_mod_items(&mut self, term: &token::Token, inner_lo: Span) -> PResult<'a, Mod> {
6401 let mut items = vec![];
6402 while let Some(item) = self.parse_item()? {
6406 if !self.eat(term) {
6407 let token_str = self.this_token_descr();
6408 let mut err = self.fatal(&format!("expected item, found {}", token_str));
6409 if self.token == token::Semi {
6410 let msg = "consider removing this semicolon";
6411 err.span_suggestion_short_with_applicability(
6412 self.span, msg, String::new(), Applicability::MachineApplicable
6414 if !items.is_empty() { // Issue #51603
6415 let previous_item = &items[items.len()-1];
6416 let previous_item_kind_name = match previous_item.node {
6417 // say "braced struct" because tuple-structs and
6418 // braceless-empty-struct declarations do take a semicolon
6419 ItemKind::Struct(..) => Some("braced struct"),
6420 ItemKind::Enum(..) => Some("enum"),
6421 ItemKind::Trait(..) => Some("trait"),
6422 ItemKind::Union(..) => Some("union"),
6425 if let Some(name) = previous_item_kind_name {
6426 err.help(&format!("{} declarations are not followed by a semicolon",
6431 err.span_label(self.span, "expected item");
6436 let hi = if self.span.is_dummy() {
6443 inner: inner_lo.to(hi),
6449 fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
6450 let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?;
6451 self.expect(&token::Colon)?;
6452 let ty = self.parse_ty()?;
6453 self.expect(&token::Eq)?;
6454 let e = self.parse_expr()?;
6455 self.expect(&token::Semi)?;
6456 let item = match m {
6457 Some(m) => ItemKind::Static(ty, m, e),
6458 None => ItemKind::Const(ty, e),
6460 Ok((id, item, None))
6463 /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
6464 fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
6465 let (in_cfg, outer_attrs) = {
6466 let mut strip_unconfigured = ::config::StripUnconfigured {
6468 features: None, // don't perform gated feature checking
6470 let outer_attrs = strip_unconfigured.process_cfg_attrs(outer_attrs.to_owned());
6471 (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), outer_attrs)
6474 let id_span = self.span;
6475 let id = self.parse_ident()?;
6476 if self.eat(&token::Semi) {
6477 if in_cfg && self.recurse_into_file_modules {
6478 // This mod is in an external file. Let's go get it!
6479 let ModulePathSuccess { path, directory_ownership, warn } =
6480 self.submod_path(id, &outer_attrs, id_span)?;
6481 let (module, mut attrs) =
6482 self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
6483 // Record that we fetched the mod from an external file
6485 let attr = Attribute {
6486 id: attr::mk_attr_id(),
6487 style: ast::AttrStyle::Outer,
6488 path: ast::Path::from_ident(Ident::from_str("warn_directory_ownership")),
6489 tokens: TokenStream::empty(),
6490 is_sugared_doc: false,
6491 span: syntax_pos::DUMMY_SP,
6493 attr::mark_known(&attr);
6496 Ok((id, ItemKind::Mod(module), Some(attrs)))
6498 let placeholder = ast::Mod {
6499 inner: syntax_pos::DUMMY_SP,
6503 Ok((id, ItemKind::Mod(placeholder), None))
6506 let old_directory = self.directory.clone();
6507 self.push_directory(id, &outer_attrs);
6509 self.expect(&token::OpenDelim(token::Brace))?;
6510 let mod_inner_lo = self.span;
6511 let attrs = self.parse_inner_attributes()?;
6512 let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
6514 self.directory = old_directory;
6515 Ok((id, ItemKind::Mod(module), Some(attrs)))
6519 fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
6520 if let Some(path) = attr::first_attr_value_str_by_name(attrs, "path") {
6521 self.directory.path.to_mut().push(&path.as_str());
6522 self.directory.ownership = DirectoryOwnership::Owned { relative: None };
6524 // We have to push on the current module name in the case of relative
6525 // paths in order to ensure that any additional module paths from inline
6526 // `mod x { ... }` come after the relative extension.
6528 // For example, a `mod z { ... }` inside `x/y.rs` should set the current
6529 // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
6530 if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
6531 if let Some(ident) = relative.take() { // remove the relative offset
6532 self.directory.path.to_mut().push(ident.as_str());
6535 self.directory.path.to_mut().push(&id.as_str());
6539 pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
6540 if let Some(s) = attr::first_attr_value_str_by_name(attrs, "path") {
6543 // On windows, the base path might have the form
6544 // `\\?\foo\bar` in which case it does not tolerate
6545 // mixed `/` and `\` separators, so canonicalize
6548 let s = s.replace("/", "\\");
6549 Some(dir_path.join(s))
6555 /// Returns either a path to a module, or .
6556 pub fn default_submod_path(
6558 relative: Option<ast::Ident>,
6560 source_map: &SourceMap) -> ModulePath
6562 // If we're in a foo.rs file instead of a mod.rs file,
6563 // we need to look for submodules in
6564 // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
6565 // `./<id>.rs` and `./<id>/mod.rs`.
6566 let relative_prefix_string;
6567 let relative_prefix = if let Some(ident) = relative {
6568 relative_prefix_string = format!("{}{}", ident.as_str(), path::MAIN_SEPARATOR);
6569 &relative_prefix_string
6574 let mod_name = id.to_string();
6575 let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
6576 let secondary_path_str = format!("{}{}{}mod.rs",
6577 relative_prefix, mod_name, path::MAIN_SEPARATOR);
6578 let default_path = dir_path.join(&default_path_str);
6579 let secondary_path = dir_path.join(&secondary_path_str);
6580 let default_exists = source_map.file_exists(&default_path);
6581 let secondary_exists = source_map.file_exists(&secondary_path);
6583 let result = match (default_exists, secondary_exists) {
6584 (true, false) => Ok(ModulePathSuccess {
6586 directory_ownership: DirectoryOwnership::Owned {
6591 (false, true) => Ok(ModulePathSuccess {
6592 path: secondary_path,
6593 directory_ownership: DirectoryOwnership::Owned {
6598 (false, false) => Err(Error::FileNotFoundForModule {
6599 mod_name: mod_name.clone(),
6600 default_path: default_path_str,
6601 secondary_path: secondary_path_str,
6602 dir_path: dir_path.display().to_string(),
6604 (true, true) => Err(Error::DuplicatePaths {
6605 mod_name: mod_name.clone(),
6606 default_path: default_path_str,
6607 secondary_path: secondary_path_str,
6613 path_exists: default_exists || secondary_exists,
6618 fn submod_path(&mut self,
6620 outer_attrs: &[Attribute],
6622 -> PResult<'a, ModulePathSuccess> {
6623 if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
6624 return Ok(ModulePathSuccess {
6625 directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
6626 // All `#[path]` files are treated as though they are a `mod.rs` file.
6627 // This means that `mod foo;` declarations inside `#[path]`-included
6628 // files are siblings,
6630 // Note that this will produce weirdness when a file named `foo.rs` is
6631 // `#[path]` included and contains a `mod foo;` declaration.
6632 // If you encounter this, it's your own darn fault :P
6633 Some(_) => DirectoryOwnership::Owned { relative: None },
6634 _ => DirectoryOwnership::UnownedViaMod(true),
6641 let relative = match self.directory.ownership {
6642 DirectoryOwnership::Owned { relative } => relative,
6643 DirectoryOwnership::UnownedViaBlock |
6644 DirectoryOwnership::UnownedViaMod(_) => None,
6646 let paths = Parser::default_submod_path(
6647 id, relative, &self.directory.path, self.sess.source_map());
6649 match self.directory.ownership {
6650 DirectoryOwnership::Owned { .. } => {
6651 paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
6653 DirectoryOwnership::UnownedViaBlock => {
6655 "Cannot declare a non-inline module inside a block \
6656 unless it has a path attribute";
6657 let mut err = self.diagnostic().struct_span_err(id_sp, msg);
6658 if paths.path_exists {
6659 let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
6661 err.span_note(id_sp, &msg);
6665 DirectoryOwnership::UnownedViaMod(warn) => {
6667 if let Ok(result) = paths.result {
6668 return Ok(ModulePathSuccess { warn: true, ..result });
6671 let mut err = self.diagnostic().struct_span_err(id_sp,
6672 "cannot declare a new module at this location");
6673 if !id_sp.is_dummy() {
6674 let src_path = self.sess.source_map().span_to_filename(id_sp);
6675 if let FileName::Real(src_path) = src_path {
6676 if let Some(stem) = src_path.file_stem() {
6677 let mut dest_path = src_path.clone();
6678 dest_path.set_file_name(stem);
6679 dest_path.push("mod.rs");
6680 err.span_note(id_sp,
6681 &format!("maybe move this module `{}` to its own \
6682 directory via `{}`", src_path.display(),
6683 dest_path.display()));
6687 if paths.path_exists {
6688 err.span_note(id_sp,
6689 &format!("... or maybe `use` the module `{}` instead \
6690 of possibly redeclaring it",
6698 /// Read a module from a source file.
6699 fn eval_src_mod(&mut self,
6701 directory_ownership: DirectoryOwnership,
6704 -> PResult<'a, (ast::Mod, Vec<Attribute> )> {
6705 let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
6706 if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
6707 let mut err = String::from("circular modules: ");
6708 let len = included_mod_stack.len();
6709 for p in &included_mod_stack[i.. len] {
6710 err.push_str(&p.to_string_lossy());
6711 err.push_str(" -> ");
6713 err.push_str(&path.to_string_lossy());
6714 return Err(self.span_fatal(id_sp, &err[..]));
6716 included_mod_stack.push(path.clone());
6717 drop(included_mod_stack);
6720 new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
6721 p0.cfg_mods = self.cfg_mods;
6722 let mod_inner_lo = p0.span;
6723 let mod_attrs = p0.parse_inner_attributes()?;
6724 let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
6726 self.sess.included_mod_stack.borrow_mut().pop();
6730 /// Parse a function declaration from a foreign module
6731 fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6732 -> PResult<'a, ForeignItem> {
6733 self.expect_keyword(keywords::Fn)?;
6735 let (ident, mut generics) = self.parse_fn_header()?;
6736 let decl = self.parse_fn_decl(true)?;
6737 generics.where_clause = self.parse_where_clause()?;
6739 self.expect(&token::Semi)?;
6740 Ok(ast::ForeignItem {
6743 node: ForeignItemKind::Fn(decl, generics),
6744 id: ast::DUMMY_NODE_ID,
6750 /// Parse a static item from a foreign module.
6751 /// Assumes that the `static` keyword is already parsed.
6752 fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6753 -> PResult<'a, ForeignItem> {
6754 let mutbl = self.eat_keyword(keywords::Mut);
6755 let ident = self.parse_ident()?;
6756 self.expect(&token::Colon)?;
6757 let ty = self.parse_ty()?;
6759 self.expect(&token::Semi)?;
6763 node: ForeignItemKind::Static(ty, mutbl),
6764 id: ast::DUMMY_NODE_ID,
6770 /// Parse a type from a foreign module
6771 fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6772 -> PResult<'a, ForeignItem> {
6773 self.expect_keyword(keywords::Type)?;
6775 let ident = self.parse_ident()?;
6777 self.expect(&token::Semi)?;
6778 Ok(ast::ForeignItem {
6781 node: ForeignItemKind::Ty,
6782 id: ast::DUMMY_NODE_ID,
6788 fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
6789 let error_msg = "crate name using dashes are not valid in `extern crate` statements";
6790 let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
6792 let mut ident = if self.token.is_keyword(keywords::SelfLower) {
6793 self.parse_path_segment_ident()
6797 let mut idents = vec![];
6798 let mut replacement = vec![];
6799 let mut fixed_crate_name = false;
6800 // Accept `extern crate name-like-this` for better diagnostics
6801 let dash = token::Token::BinOp(token::BinOpToken::Minus);
6802 if self.token == dash { // Do not include `-` as part of the expected tokens list
6803 while self.eat(&dash) {
6804 fixed_crate_name = true;
6805 replacement.push((self.prev_span, "_".to_string()));
6806 idents.push(self.parse_ident()?);
6809 if fixed_crate_name {
6810 let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
6811 let mut fixed_name = format!("{}", ident.name);
6812 for part in idents {
6813 fixed_name.push_str(&format!("_{}", part.name));
6815 ident = Ident::from_str(&fixed_name).with_span_pos(fixed_name_sp);
6817 let mut err = self.struct_span_err(fixed_name_sp, error_msg);
6818 err.span_label(fixed_name_sp, "dash-separated idents are not valid");
6819 err.multipart_suggestion(suggestion_msg, replacement);
6825 /// Parse extern crate links
6829 /// extern crate foo;
6830 /// extern crate bar as foo;
6831 fn parse_item_extern_crate(&mut self,
6833 visibility: Visibility,
6834 attrs: Vec<Attribute>)
6835 -> PResult<'a, P<Item>> {
6836 // Accept `extern crate name-like-this` for better diagnostics
6837 let orig_name = self.parse_crate_name_with_dashes()?;
6838 let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
6839 (rename, Some(orig_name.name))
6843 self.expect(&token::Semi)?;
6845 let span = lo.to(self.prev_span);
6846 Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
6849 /// Parse `extern` for foreign ABIs
6852 /// `extern` is expected to have been
6853 /// consumed before calling this method
6859 fn parse_item_foreign_mod(&mut self,
6861 opt_abi: Option<Abi>,
6862 visibility: Visibility,
6863 mut attrs: Vec<Attribute>)
6864 -> PResult<'a, P<Item>> {
6865 self.expect(&token::OpenDelim(token::Brace))?;
6867 let abi = opt_abi.unwrap_or(Abi::C);
6869 attrs.extend(self.parse_inner_attributes()?);
6871 let mut foreign_items = vec![];
6872 while !self.eat(&token::CloseDelim(token::Brace)) {
6873 foreign_items.push(self.parse_foreign_item()?);
6876 let prev_span = self.prev_span;
6877 let m = ast::ForeignMod {
6879 items: foreign_items
6881 let invalid = keywords::Invalid.ident();
6882 Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
6885 /// Parse `type Foo = Bar;`
6887 /// `existential type Foo: Bar;`
6889 /// `return None` without modifying the parser state
6890 fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
6891 // This parses the grammar:
6892 // Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
6893 if self.check_keyword(keywords::Type) ||
6894 self.check_keyword(keywords::Existential) &&
6895 self.look_ahead(1, |t| t.is_keyword(keywords::Type)) {
6896 let existential = self.eat_keyword(keywords::Existential);
6897 assert!(self.eat_keyword(keywords::Type));
6898 Some(self.parse_existential_or_alias(existential))
6904 /// Parse type alias or existential type
6905 fn parse_existential_or_alias(
6908 ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
6909 let ident = self.parse_ident()?;
6910 let mut tps = self.parse_generics()?;
6911 tps.where_clause = self.parse_where_clause()?;
6912 let alias = if existential {
6913 self.expect(&token::Colon)?;
6914 let bounds = self.parse_generic_bounds()?;
6915 AliasKind::Existential(bounds)
6917 self.expect(&token::Eq)?;
6918 let ty = self.parse_ty()?;
6921 self.expect(&token::Semi)?;
6922 Ok((ident, alias, tps))
6925 /// Parse the part of an "enum" decl following the '{'
6926 fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
6927 let mut variants = Vec::new();
6928 let mut all_nullary = true;
6929 let mut any_disr = None;
6930 while self.token != token::CloseDelim(token::Brace) {
6931 let variant_attrs = self.parse_outer_attributes()?;
6932 let vlo = self.span;
6935 let mut disr_expr = None;
6936 let ident = self.parse_ident()?;
6937 if self.check(&token::OpenDelim(token::Brace)) {
6938 // Parse a struct variant.
6939 all_nullary = false;
6940 struct_def = VariantData::Struct(self.parse_record_struct_body()?,
6941 ast::DUMMY_NODE_ID);
6942 } else if self.check(&token::OpenDelim(token::Paren)) {
6943 all_nullary = false;
6944 struct_def = VariantData::Tuple(self.parse_tuple_struct_body()?,
6945 ast::DUMMY_NODE_ID);
6946 } else if self.eat(&token::Eq) {
6947 disr_expr = Some(AnonConst {
6948 id: ast::DUMMY_NODE_ID,
6949 value: self.parse_expr()?,
6951 any_disr = disr_expr.as_ref().map(|c| c.value.span);
6952 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6954 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6957 let vr = ast::Variant_ {
6959 attrs: variant_attrs,
6963 variants.push(respan(vlo.to(self.prev_span), vr));
6965 if !self.eat(&token::Comma) { break; }
6967 self.expect(&token::CloseDelim(token::Brace))?;
6969 Some(disr_span) if !all_nullary =>
6970 self.span_err(disr_span,
6971 "discriminator values can only be used with a field-less enum"),
6975 Ok(ast::EnumDef { variants })
6978 /// Parse an "enum" declaration
6979 fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
6980 let id = self.parse_ident()?;
6981 let mut generics = self.parse_generics()?;
6982 generics.where_clause = self.parse_where_clause()?;
6983 self.expect(&token::OpenDelim(token::Brace))?;
6985 let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
6986 self.recover_stmt();
6987 self.eat(&token::CloseDelim(token::Brace));
6990 Ok((id, ItemKind::Enum(enum_definition, generics), None))
6993 /// Parses a string as an ABI spec on an extern type or module. Consumes
6994 /// the `extern` keyword, if one is found.
6995 fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
6997 token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
6999 self.expect_no_suffix(sp, "ABI spec", suf);
7001 match abi::lookup(&s.as_str()) {
7002 Some(abi) => Ok(Some(abi)),
7004 let prev_span = self.prev_span;
7005 let mut err = struct_span_err!(
7006 self.sess.span_diagnostic,
7009 "invalid ABI: found `{}`",
7011 err.span_label(prev_span, "invalid ABI");
7012 err.help(&format!("valid ABIs: {}", abi::all_names().join(", ")));
7023 fn is_static_global(&mut self) -> bool {
7024 if self.check_keyword(keywords::Static) {
7025 // Check if this could be a closure
7026 !self.look_ahead(1, |token| {
7027 if token.is_keyword(keywords::Move) {
7031 token::BinOp(token::Or) | token::OrOr => true,
7042 attrs: Vec<Attribute>,
7043 macros_allowed: bool,
7044 attributes_allowed: bool,
7045 ) -> PResult<'a, Option<P<Item>>> {
7046 let (ret, tokens) = self.collect_tokens(|this| {
7047 this.parse_item_implementation(attrs, macros_allowed, attributes_allowed)
7050 // Once we've parsed an item and recorded the tokens we got while
7051 // parsing we may want to store `tokens` into the item we're about to
7052 // return. Note, though, that we specifically didn't capture tokens
7053 // related to outer attributes. The `tokens` field here may later be
7054 // used with procedural macros to convert this item back into a token
7055 // stream, but during expansion we may be removing attributes as we go
7058 // If we've got inner attributes then the `tokens` we've got above holds
7059 // these inner attributes. If an inner attribute is expanded we won't
7060 // actually remove it from the token stream, so we'll just keep yielding
7061 // it (bad!). To work around this case for now we just avoid recording
7062 // `tokens` if we detect any inner attributes. This should help keep
7063 // expansion correct, but we should fix this bug one day!
7066 if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
7067 i.tokens = Some(tokens);
7074 /// Parse one of the items allowed by the flags.
7075 fn parse_item_implementation(
7077 attrs: Vec<Attribute>,
7078 macros_allowed: bool,
7079 attributes_allowed: bool,
7080 ) -> PResult<'a, Option<P<Item>>> {
7081 maybe_whole!(self, NtItem, |item| {
7082 let mut item = item.into_inner();
7083 let mut attrs = attrs;
7084 mem::swap(&mut item.attrs, &mut attrs);
7085 item.attrs.extend(attrs);
7091 let visibility = self.parse_visibility(false)?;
7093 if self.eat_keyword(keywords::Use) {
7095 let item_ = ItemKind::Use(P(self.parse_use_tree()?));
7096 self.expect(&token::Semi)?;
7098 let span = lo.to(self.prev_span);
7099 let item = self.mk_item(span, keywords::Invalid.ident(), item_, visibility, attrs);
7100 return Ok(Some(item));
7103 if self.check_keyword(keywords::Extern) && self.is_extern_non_path() {
7104 self.bump(); // `extern`
7105 if self.eat_keyword(keywords::Crate) {
7106 return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
7109 let opt_abi = self.parse_opt_abi()?;
7111 if self.eat_keyword(keywords::Fn) {
7112 // EXTERN FUNCTION ITEM
7113 let fn_span = self.prev_span;
7114 let abi = opt_abi.unwrap_or(Abi::C);
7115 let (ident, item_, extra_attrs) =
7116 self.parse_item_fn(Unsafety::Normal,
7118 respan(fn_span, Constness::NotConst),
7120 let prev_span = self.prev_span;
7121 let item = self.mk_item(lo.to(prev_span),
7125 maybe_append(attrs, extra_attrs));
7126 return Ok(Some(item));
7127 } else if self.check(&token::OpenDelim(token::Brace)) {
7128 return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
7134 if self.is_static_global() {
7137 let m = if self.eat_keyword(keywords::Mut) {
7140 Mutability::Immutable
7142 let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
7143 let prev_span = self.prev_span;
7144 let item = self.mk_item(lo.to(prev_span),
7148 maybe_append(attrs, extra_attrs));
7149 return Ok(Some(item));
7151 if self.eat_keyword(keywords::Const) {
7152 let const_span = self.prev_span;
7153 if self.check_keyword(keywords::Fn)
7154 || (self.check_keyword(keywords::Unsafe)
7155 && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
7156 // CONST FUNCTION ITEM
7157 let unsafety = self.parse_unsafety();
7159 let (ident, item_, extra_attrs) =
7160 self.parse_item_fn(unsafety,
7162 respan(const_span, Constness::Const),
7164 let prev_span = self.prev_span;
7165 let item = self.mk_item(lo.to(prev_span),
7169 maybe_append(attrs, extra_attrs));
7170 return Ok(Some(item));
7174 if self.eat_keyword(keywords::Mut) {
7175 let prev_span = self.prev_span;
7176 self.diagnostic().struct_span_err(prev_span, "const globals cannot be mutable")
7177 .help("did you mean to declare a static?")
7180 let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
7181 let prev_span = self.prev_span;
7182 let item = self.mk_item(lo.to(prev_span),
7186 maybe_append(attrs, extra_attrs));
7187 return Ok(Some(item));
7190 // `unsafe async fn` or `async fn`
7192 self.check_keyword(keywords::Unsafe) &&
7193 self.look_ahead(1, |t| t.is_keyword(keywords::Async))
7195 self.check_keyword(keywords::Async) &&
7196 self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
7199 // ASYNC FUNCTION ITEM
7200 let unsafety = self.parse_unsafety();
7201 self.expect_keyword(keywords::Async)?;
7202 self.expect_keyword(keywords::Fn)?;
7203 let fn_span = self.prev_span;
7204 let (ident, item_, extra_attrs) =
7205 self.parse_item_fn(unsafety,
7207 closure_id: ast::DUMMY_NODE_ID,
7208 return_impl_trait_id: ast::DUMMY_NODE_ID,
7210 respan(fn_span, Constness::NotConst),
7212 let prev_span = self.prev_span;
7213 let item = self.mk_item(lo.to(prev_span),
7217 maybe_append(attrs, extra_attrs));
7218 return Ok(Some(item));
7220 if self.check_keyword(keywords::Unsafe) &&
7221 (self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) ||
7222 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)))
7224 // UNSAFE TRAIT ITEM
7225 self.bump(); // `unsafe`
7226 let is_auto = if self.eat_keyword(keywords::Trait) {
7229 self.expect_keyword(keywords::Auto)?;
7230 self.expect_keyword(keywords::Trait)?;
7233 let (ident, item_, extra_attrs) =
7234 self.parse_item_trait(is_auto, Unsafety::Unsafe)?;
7235 let prev_span = self.prev_span;
7236 let item = self.mk_item(lo.to(prev_span),
7240 maybe_append(attrs, extra_attrs));
7241 return Ok(Some(item));
7243 if self.check_keyword(keywords::Impl) ||
7244 self.check_keyword(keywords::Unsafe) &&
7245 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7246 self.check_keyword(keywords::Default) &&
7247 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7248 self.check_keyword(keywords::Default) &&
7249 self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) {
7251 let defaultness = self.parse_defaultness();
7252 let unsafety = self.parse_unsafety();
7253 self.expect_keyword(keywords::Impl)?;
7254 let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?;
7255 let span = lo.to(self.prev_span);
7256 return Ok(Some(self.mk_item(span, ident, item, visibility,
7257 maybe_append(attrs, extra_attrs))));
7259 if self.check_keyword(keywords::Fn) {
7262 let fn_span = self.prev_span;
7263 let (ident, item_, extra_attrs) =
7264 self.parse_item_fn(Unsafety::Normal,
7266 respan(fn_span, Constness::NotConst),
7268 let prev_span = self.prev_span;
7269 let item = self.mk_item(lo.to(prev_span),
7273 maybe_append(attrs, extra_attrs));
7274 return Ok(Some(item));
7276 if self.check_keyword(keywords::Unsafe)
7277 && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
7278 // UNSAFE FUNCTION ITEM
7279 self.bump(); // `unsafe`
7280 // `{` is also expected after `unsafe`, in case of error, include it in the diagnostic
7281 self.check(&token::OpenDelim(token::Brace));
7282 let abi = if self.eat_keyword(keywords::Extern) {
7283 self.parse_opt_abi()?.unwrap_or(Abi::C)
7287 self.expect_keyword(keywords::Fn)?;
7288 let fn_span = self.prev_span;
7289 let (ident, item_, extra_attrs) =
7290 self.parse_item_fn(Unsafety::Unsafe,
7292 respan(fn_span, Constness::NotConst),
7294 let prev_span = self.prev_span;
7295 let item = self.mk_item(lo.to(prev_span),
7299 maybe_append(attrs, extra_attrs));
7300 return Ok(Some(item));
7302 if self.eat_keyword(keywords::Mod) {
7304 let (ident, item_, extra_attrs) =
7305 self.parse_item_mod(&attrs[..])?;
7306 let prev_span = self.prev_span;
7307 let item = self.mk_item(lo.to(prev_span),
7311 maybe_append(attrs, extra_attrs));
7312 return Ok(Some(item));
7314 if let Some(type_) = self.eat_type() {
7315 let (ident, alias, generics) = type_?;
7317 let item_ = match alias {
7318 AliasKind::Weak(ty) => ItemKind::Ty(ty, generics),
7319 AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics),
7321 let prev_span = self.prev_span;
7322 let item = self.mk_item(lo.to(prev_span),
7327 return Ok(Some(item));
7329 if self.eat_keyword(keywords::Enum) {
7331 let (ident, item_, extra_attrs) = self.parse_item_enum()?;
7332 let prev_span = self.prev_span;
7333 let item = self.mk_item(lo.to(prev_span),
7337 maybe_append(attrs, extra_attrs));
7338 return Ok(Some(item));
7340 if self.check_keyword(keywords::Trait)
7341 || (self.check_keyword(keywords::Auto)
7342 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
7344 let is_auto = if self.eat_keyword(keywords::Trait) {
7347 self.expect_keyword(keywords::Auto)?;
7348 self.expect_keyword(keywords::Trait)?;
7352 let (ident, item_, extra_attrs) =
7353 self.parse_item_trait(is_auto, Unsafety::Normal)?;
7354 let prev_span = self.prev_span;
7355 let item = self.mk_item(lo.to(prev_span),
7359 maybe_append(attrs, extra_attrs));
7360 return Ok(Some(item));
7362 if self.eat_keyword(keywords::Struct) {
7364 let (ident, item_, extra_attrs) = self.parse_item_struct()?;
7365 let prev_span = self.prev_span;
7366 let item = self.mk_item(lo.to(prev_span),
7370 maybe_append(attrs, extra_attrs));
7371 return Ok(Some(item));
7373 if self.is_union_item() {
7376 let (ident, item_, extra_attrs) = self.parse_item_union()?;
7377 let prev_span = self.prev_span;
7378 let item = self.mk_item(lo.to(prev_span),
7382 maybe_append(attrs, extra_attrs));
7383 return Ok(Some(item));
7385 if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, lo)? {
7386 return Ok(Some(macro_def));
7389 // Verify whether we have encountered a struct or method definition where the user forgot to
7390 // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
7391 if visibility.node.is_pub() &&
7392 self.check_ident() &&
7393 self.look_ahead(1, |t| *t != token::Not)
7395 // Space between `pub` keyword and the identifier
7398 // ^^^ `sp` points here
7399 let sp = self.prev_span.between(self.span);
7400 let full_sp = self.prev_span.to(self.span);
7401 let ident_sp = self.span;
7402 if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
7403 // possible public struct definition where `struct` was forgotten
7404 let ident = self.parse_ident().unwrap();
7405 let msg = format!("add `struct` here to parse `{}` as a public struct",
7407 let mut err = self.diagnostic()
7408 .struct_span_err(sp, "missing `struct` for struct definition");
7409 err.span_suggestion_short_with_applicability(
7410 sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
7413 } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
7414 let ident = self.parse_ident().unwrap();
7416 let kw_name = if let Ok(Some(_)) = self.parse_self_arg() {
7421 self.consume_block(token::Paren);
7422 let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) {
7423 self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]);
7425 ("fn", kw_name, false)
7426 } else if self.check(&token::OpenDelim(token::Brace)) {
7428 ("fn", kw_name, false)
7429 } else if self.check(&token::Colon) {
7433 ("fn` or `struct", "function or struct", true)
7435 self.consume_block(token::Brace);
7437 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7438 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7440 let suggestion = format!("add `{}` here to parse `{}` as a public {}",
7444 err.span_suggestion_short_with_applicability(
7445 sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
7448 if let Ok(snippet) = self.sess.source_map().span_to_snippet(ident_sp) {
7449 err.span_suggestion_with_applicability(
7451 "if you meant to call a macro, try",
7452 format!("{}!", snippet),
7453 // this is the `ambiguous` conditional branch
7454 Applicability::MaybeIncorrect
7457 err.help("if you meant to call a macro, remove the `pub` \
7458 and add a trailing `!` after the identifier");
7462 } else if self.look_ahead(1, |t| *t == token::Lt) {
7463 let ident = self.parse_ident().unwrap();
7464 self.eat_to_tokens(&[&token::Gt]);
7466 let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) {
7467 if let Ok(Some(_)) = self.parse_self_arg() {
7468 ("fn", "method", false)
7470 ("fn", "function", false)
7472 } else if self.check(&token::OpenDelim(token::Brace)) {
7473 ("struct", "struct", false)
7475 ("fn` or `struct", "function or struct", true)
7477 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7478 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7480 err.span_suggestion_short_with_applicability(
7482 &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name),
7483 format!(" {} ", kw),
7484 Applicability::MachineApplicable,
7490 self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, visibility)
7493 /// Parse a foreign item.
7494 crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> {
7495 maybe_whole!(self, NtForeignItem, |ni| ni);
7497 let attrs = self.parse_outer_attributes()?;
7499 let visibility = self.parse_visibility(false)?;
7501 // FOREIGN STATIC ITEM
7502 // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
7503 if self.check_keyword(keywords::Static) || self.token.is_keyword(keywords::Const) {
7504 if self.token.is_keyword(keywords::Const) {
7506 .struct_span_err(self.span, "extern items cannot be `const`")
7507 .span_suggestion_with_applicability(
7509 "try using a static value",
7510 "static".to_owned(),
7511 Applicability::MachineApplicable
7514 self.bump(); // `static` or `const`
7515 return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
7517 // FOREIGN FUNCTION ITEM
7518 if self.check_keyword(keywords::Fn) {
7519 return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?);
7521 // FOREIGN TYPE ITEM
7522 if self.check_keyword(keywords::Type) {
7523 return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
7526 match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
7530 ident: keywords::Invalid.ident(),
7531 span: lo.to(self.prev_span),
7532 id: ast::DUMMY_NODE_ID,
7535 node: ForeignItemKind::Macro(mac),
7540 if !attrs.is_empty() {
7541 self.expected_item_err(&attrs);
7549 /// This is the fall-through for parsing items.
7550 fn parse_macro_use_or_failure(
7552 attrs: Vec<Attribute> ,
7553 macros_allowed: bool,
7554 attributes_allowed: bool,
7556 visibility: Visibility
7557 ) -> PResult<'a, Option<P<Item>>> {
7558 if macros_allowed && self.token.is_path_start() {
7559 // MACRO INVOCATION ITEM
7561 let prev_span = self.prev_span;
7562 self.complain_if_pub_macro(&visibility.node, prev_span);
7564 let mac_lo = self.span;
7567 let pth = self.parse_path(PathStyle::Mod)?;
7568 self.expect(&token::Not)?;
7570 // a 'special' identifier (like what `macro_rules!` uses)
7571 // is optional. We should eventually unify invoc syntax
7573 let id = if self.token.is_ident() {
7576 keywords::Invalid.ident() // no special identifier
7578 // eat a matched-delimiter token tree:
7579 let (delim, tts) = self.expect_delimited_token_tree()?;
7580 if delim != MacDelimiter::Brace {
7581 if !self.eat(&token::Semi) {
7582 self.span_err(self.prev_span,
7583 "macros that expand to items must either \
7584 be surrounded with braces or followed by \
7589 let hi = self.prev_span;
7590 let mac = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim });
7591 let item = self.mk_item(lo.to(hi), id, ItemKind::Mac(mac), visibility, attrs);
7592 return Ok(Some(item));
7595 // FAILURE TO PARSE ITEM
7596 match visibility.node {
7597 VisibilityKind::Inherited => {}
7599 return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
7603 if !attributes_allowed && !attrs.is_empty() {
7604 self.expected_item_err(&attrs);
7609 /// Parse a macro invocation inside a `trait`, `impl` or `extern` block
7610 fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
7611 at_end: &mut bool) -> PResult<'a, Option<Mac>>
7613 if self.token.is_path_start() && !self.is_extern_non_path() {
7614 let prev_span = self.prev_span;
7616 let pth = self.parse_path(PathStyle::Mod)?;
7618 if pth.segments.len() == 1 {
7619 if !self.eat(&token::Not) {
7620 return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
7623 self.expect(&token::Not)?;
7626 if let Some(vis) = vis {
7627 self.complain_if_pub_macro(&vis.node, prev_span);
7632 // eat a matched-delimiter token tree:
7633 let (delim, tts) = self.expect_delimited_token_tree()?;
7634 if delim != MacDelimiter::Brace {
7635 self.expect(&token::Semi)?
7638 Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim })))
7644 fn collect_tokens<F, R>(&mut self, f: F) -> PResult<'a, (R, TokenStream)>
7645 where F: FnOnce(&mut Self) -> PResult<'a, R>
7647 // Record all tokens we parse when parsing this item.
7648 let mut tokens = Vec::new();
7649 let prev_collecting = match self.token_cursor.frame.last_token {
7650 LastToken::Collecting(ref mut list) => {
7651 Some(mem::replace(list, Vec::new()))
7653 LastToken::Was(ref mut last) => {
7654 tokens.extend(last.take());
7658 self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
7659 let prev = self.token_cursor.stack.len();
7661 let last_token = if self.token_cursor.stack.len() == prev {
7662 &mut self.token_cursor.frame.last_token
7664 &mut self.token_cursor.stack[prev].last_token
7667 // Pull our the toekns that we've collected from the call to `f` above
7668 let mut collected_tokens = match *last_token {
7669 LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()),
7670 LastToken::Was(_) => panic!("our vector went away?"),
7673 // If we're not at EOF our current token wasn't actually consumed by
7674 // `f`, but it'll still be in our list that we pulled out. In that case
7676 let extra_token = if self.token != token::Eof {
7677 collected_tokens.pop()
7682 // If we were previously collecting tokens, then this was a recursive
7683 // call. In that case we need to record all the tokens we collected in
7684 // our parent list as well. To do that we push a clone of our stream
7685 // onto the previous list.
7686 let stream = collected_tokens.into_iter().collect::<TokenStream>();
7687 match prev_collecting {
7689 list.push(stream.clone());
7690 list.extend(extra_token);
7691 *last_token = LastToken::Collecting(list);
7694 *last_token = LastToken::Was(extra_token);
7701 pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
7702 let attrs = self.parse_outer_attributes()?;
7703 self.parse_item_(attrs, true, false)
7707 fn is_import_coupler(&mut self) -> bool {
7708 self.check(&token::ModSep) &&
7709 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
7710 *t == token::BinOp(token::Star))
7715 /// USE_TREE = [`::`] `*` |
7716 /// [`::`] `{` USE_TREE_LIST `}` |
7718 /// PATH `::` `{` USE_TREE_LIST `}` |
7719 /// PATH [`as` IDENT]
7720 fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
7723 let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
7724 let kind = if self.check(&token::OpenDelim(token::Brace)) ||
7725 self.check(&token::BinOp(token::Star)) ||
7726 self.is_import_coupler() {
7727 // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
7728 let mod_sep_ctxt = self.span.ctxt();
7729 if self.eat(&token::ModSep) {
7730 prefix.segments.push(
7731 PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
7735 if self.eat(&token::BinOp(token::Star)) {
7738 UseTreeKind::Nested(self.parse_use_tree_list()?)
7741 // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
7742 prefix = self.parse_path(PathStyle::Mod)?;
7744 if self.eat(&token::ModSep) {
7745 if self.eat(&token::BinOp(token::Star)) {
7748 UseTreeKind::Nested(self.parse_use_tree_list()?)
7751 UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID)
7755 Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
7758 /// Parse UseTreeKind::Nested(list)
7760 /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
7761 fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
7762 self.parse_unspanned_seq(&token::OpenDelim(token::Brace),
7763 &token::CloseDelim(token::Brace),
7764 SeqSep::trailing_allowed(token::Comma), |this| {
7765 Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID))
7769 fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
7770 if self.eat_keyword(keywords::As) {
7771 self.parse_ident_or_underscore().map(Some)
7777 /// Parses a source module as a crate. This is the main
7778 /// entry point for the parser.
7779 pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
7782 attrs: self.parse_inner_attributes()?,
7783 module: self.parse_mod_items(&token::Eof, lo)?,
7784 span: lo.to(self.span),
7788 pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
7789 let ret = match self.token {
7790 token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf),
7791 token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf),
7798 pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
7799 match self.parse_optional_str() {
7800 Some((s, style, suf)) => {
7801 let sp = self.prev_span;
7802 self.expect_no_suffix(sp, "string literal", suf);
7806 let msg = "expected string literal";
7807 let mut err = self.fatal(msg);
7808 err.span_label(self.span, msg);