1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use rustc_target::spec::abi::{self, Abi};
12 use ast::{AngleBracketedArgs, ParenthesisedArgs, AttrStyle, BareFnTy};
13 use ast::{GenericBound, TraitBoundModifier};
15 use ast::{Mod, AnonConst, Arg, Arm, Attribute, BindingMode, TraitItemKind};
17 use ast::{BlockCheckMode, CaptureBy, Movability};
18 use ast::{Constness, Crate};
21 use ast::{Expr, ExprKind, RangeLimits};
22 use ast::{Field, FnDecl, FnHeader};
23 use ast::{ForeignItem, ForeignItemKind, FunctionRetTy};
24 use ast::{GenericParam, GenericParamKind};
26 use ast::{Ident, ImplItem, IsAsync, IsAuto, Item, ItemKind};
27 use ast::{Label, Lifetime, Lit, LitKind};
29 use ast::MacStmtStyle;
30 use ast::{Mac, Mac_, MacDelimiter};
31 use ast::{MutTy, Mutability};
32 use ast::{Pat, PatKind, PathSegment};
33 use ast::{PolyTraitRef, QSelf};
34 use ast::{Stmt, StmtKind};
35 use ast::{VariantData, StructField};
38 use ast::{TraitItem, TraitRef, TraitObjectSyntax};
39 use ast::{Ty, TyKind, TypeBinding, GenericBounds};
40 use ast::{Visibility, VisibilityKind, WhereClause, CrateSugar};
41 use ast::{UseTree, UseTreeKind};
42 use ast::{BinOpKind, UnOp};
43 use ast::{RangeEnd, RangeSyntax};
45 use source_map::{self, SourceMap, Spanned, respan};
46 use syntax_pos::{self, Span, MultiSpan, BytePos, FileName, edition::Edition};
47 use errors::{self, Applicability, DiagnosticBuilder, DiagnosticId};
48 use parse::{self, SeqSep, classify, token};
49 use parse::lexer::TokenAndSpan;
50 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
51 use parse::{new_sub_parser_from_file, ParseSess, Directory, DirectoryOwnership};
52 use util::parser::{AssocOp, Fixity};
57 use tokenstream::{self, Delimited, ThinTokenStream, TokenTree, TokenStream};
58 use symbol::{Symbol, keywords};
63 use std::path::{self, Path, PathBuf};
67 /// Whether the type alias or associated type is a concrete type or an existential type
69 /// Just a new name for the same type
71 /// Only trait impls of the type will be usable, not the actual type itself
72 Existential(GenericBounds),
76 struct Restrictions: u8 {
77 const STMT_EXPR = 1 << 0;
78 const NO_STRUCT_LITERAL = 1 << 1;
82 type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>);
84 /// How to parse a path.
85 #[derive(Copy, Clone, PartialEq)]
87 /// In some contexts, notably in expressions, paths with generic arguments are ambiguous
88 /// with something else. For example, in expressions `segment < ....` can be interpreted
89 /// as a comparison and `segment ( ....` can be interpreted as a function call.
90 /// In all such contexts the non-path interpretation is preferred by default for practical
91 /// reasons, but the path interpretation can be forced by the disambiguator `::`, e.g.
92 /// `x<y>` - comparisons, `x::<y>` - unambiguously a path.
94 /// In other contexts, notably in types, no ambiguity exists and paths can be written
95 /// without the disambiguator, e.g. `x<y>` - unambiguously a path.
96 /// Paths with disambiguators are still accepted, `x::<Y>` - unambiguously a path too.
98 /// A path with generic arguments disallowed, e.g. `foo::bar::Baz`, used in imports,
99 /// visibilities or attributes.
100 /// Technically, this variant is unnecessary and e.g. `Expr` can be used instead
101 /// (paths in "mod" contexts have to be checked later for absence of generic arguments
102 /// anyway, due to macros), but it is used to avoid weird suggestions about expected
103 /// tokens when something goes wrong.
107 #[derive(Clone, Copy, PartialEq, Debug)]
113 #[derive(Clone, Copy, PartialEq, Debug)]
119 /// Possibly accept an `token::Interpolated` expression (a pre-parsed expression
120 /// dropped into the token stream, which happens while parsing the result of
121 /// macro expansion). Placement of these is not as complex as I feared it would
122 /// be. The important thing is to make sure that lookahead doesn't balk at
123 /// `token::Interpolated` tokens.
124 macro_rules! maybe_whole_expr {
126 if let token::Interpolated(nt) = $p.token.clone() {
128 token::NtExpr(ref e) | token::NtLiteral(ref e) => {
130 return Ok((*e).clone());
132 token::NtPath(ref path) => {
135 let kind = ExprKind::Path(None, (*path).clone());
136 return Ok($p.mk_expr(span, kind, ThinVec::new()));
138 token::NtBlock(ref block) => {
141 let kind = ExprKind::Block((*block).clone(), None);
142 return Ok($p.mk_expr(span, kind, ThinVec::new()));
150 /// As maybe_whole_expr, but for things other than expressions
151 macro_rules! maybe_whole {
152 ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
153 if let token::Interpolated(nt) = $p.token.clone() {
154 if let token::$constructor($x) = nt.0.clone() {
162 fn maybe_append(mut lhs: Vec<Attribute>, mut rhs: Option<Vec<Attribute>>) -> Vec<Attribute> {
163 if let Some(ref mut rhs) = rhs {
169 #[derive(Debug, Clone, Copy, PartialEq)]
180 trait RecoverQPath: Sized {
181 const PATH_STYLE: PathStyle = PathStyle::Expr;
182 fn to_ty(&self) -> Option<P<Ty>>;
183 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self;
184 fn to_string(&self) -> String;
187 impl RecoverQPath for Ty {
188 const PATH_STYLE: PathStyle = PathStyle::Type;
189 fn to_ty(&self) -> Option<P<Ty>> {
190 Some(P(self.clone()))
192 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self {
193 Self { span: path.span, node: TyKind::Path(qself, path), id: self.id }
195 fn to_string(&self) -> String {
196 pprust::ty_to_string(self)
200 impl RecoverQPath for Pat {
201 fn to_ty(&self) -> Option<P<Ty>> {
204 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self {
205 Self { span: path.span, node: PatKind::Path(qself, path), id: self.id }
207 fn to_string(&self) -> String {
208 pprust::pat_to_string(self)
212 impl RecoverQPath for Expr {
213 fn to_ty(&self) -> Option<P<Ty>> {
216 fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self {
217 Self { span: path.span, node: ExprKind::Path(qself, path),
218 id: self.id, attrs: self.attrs.clone() }
220 fn to_string(&self) -> String {
221 pprust::expr_to_string(self)
225 /* ident is handled by common.rs */
228 pub struct Parser<'a> {
229 pub sess: &'a ParseSess,
230 /// the current token:
231 pub token: token::Token,
232 /// the span of the current token:
234 /// the span of the previous token:
235 meta_var_span: Option<Span>,
237 /// the previous token kind
238 prev_token_kind: PrevTokenKind,
239 restrictions: Restrictions,
240 /// Used to determine the path to externally loaded source files
241 crate directory: Directory<'a>,
242 /// Whether to parse sub-modules in other files.
243 pub recurse_into_file_modules: bool,
244 /// Name of the root module this parser originated from. If `None`, then the
245 /// name is not known. This does not change while the parser is descending
246 /// into modules, and sub-parsers have new values for this name.
247 pub root_module_name: Option<String>,
248 crate expected_tokens: Vec<TokenType>,
249 token_cursor: TokenCursor,
250 desugar_doc_comments: bool,
251 /// Whether we should configure out of line modules as we parse.
258 frame: TokenCursorFrame,
259 stack: Vec<TokenCursorFrame>,
263 struct TokenCursorFrame {
264 delim: token::DelimToken,
267 tree_cursor: tokenstream::Cursor,
269 last_token: LastToken,
272 /// This is used in `TokenCursorFrame` above to track tokens that are consumed
273 /// by the parser, and then that's transitively used to record the tokens that
274 /// each parse AST item is created with.
276 /// Right now this has two states, either collecting tokens or not collecting
277 /// tokens. If we're collecting tokens we just save everything off into a local
278 /// `Vec`. This should eventually though likely save tokens from the original
279 /// token stream and just use slicing of token streams to avoid creation of a
280 /// whole new vector.
282 /// The second state is where we're passively not recording tokens, but the last
283 /// token is still tracked for when we want to start recording tokens. This
284 /// "last token" means that when we start recording tokens we'll want to ensure
285 /// that this, the first token, is included in the output.
287 /// You can find some more example usage of this in the `collect_tokens` method
291 Collecting(Vec<TokenStream>),
292 Was(Option<TokenStream>),
295 impl TokenCursorFrame {
296 fn new(sp: Span, delimited: &Delimited) -> Self {
298 delim: delimited.delim,
300 open_delim: delimited.delim == token::NoDelim,
301 tree_cursor: delimited.stream().into_trees(),
302 close_delim: delimited.delim == token::NoDelim,
303 last_token: LastToken::Was(None),
309 fn next(&mut self) -> TokenAndSpan {
311 let tree = if !self.frame.open_delim {
312 self.frame.open_delim = true;
313 Delimited { delim: self.frame.delim, tts: TokenStream::empty().into() }
314 .open_tt(self.frame.span)
315 } else if let Some(tree) = self.frame.tree_cursor.next() {
317 } else if !self.frame.close_delim {
318 self.frame.close_delim = true;
319 Delimited { delim: self.frame.delim, tts: TokenStream::empty().into() }
320 .close_tt(self.frame.span)
321 } else if let Some(frame) = self.stack.pop() {
325 return TokenAndSpan { tok: token::Eof, sp: syntax_pos::DUMMY_SP }
328 match self.frame.last_token {
329 LastToken::Collecting(ref mut v) => v.push(tree.clone().into()),
330 LastToken::Was(ref mut t) => *t = Some(tree.clone().into()),
334 TokenTree::Token(sp, tok) => return TokenAndSpan { tok: tok, sp: sp },
335 TokenTree::Delimited(sp, ref delimited) => {
336 let frame = TokenCursorFrame::new(sp, delimited);
337 self.stack.push(mem::replace(&mut self.frame, frame));
343 fn next_desugared(&mut self) -> TokenAndSpan {
344 let (sp, name) = match self.next() {
345 TokenAndSpan { sp, tok: token::DocComment(name) } => (sp, name),
349 let stripped = strip_doc_comment_decoration(&name.as_str());
351 // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
352 // required to wrap the text.
353 let mut num_of_hashes = 0;
355 for ch in stripped.chars() {
358 '#' if count > 0 => count + 1,
361 num_of_hashes = cmp::max(num_of_hashes, count);
364 let body = TokenTree::Delimited(sp, Delimited {
365 delim: token::Bracket,
366 tts: [TokenTree::Token(sp, token::Ident(ast::Ident::from_str("doc"), false)),
367 TokenTree::Token(sp, token::Eq),
368 TokenTree::Token(sp, token::Literal(
369 token::StrRaw(Symbol::intern(&stripped), num_of_hashes), None))]
370 .iter().cloned().collect::<TokenStream>().into(),
373 self.stack.push(mem::replace(&mut self.frame, TokenCursorFrame::new(sp, &Delimited {
374 delim: token::NoDelim,
375 tts: if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
376 [TokenTree::Token(sp, token::Pound), TokenTree::Token(sp, token::Not), body]
377 .iter().cloned().collect::<TokenStream>().into()
379 [TokenTree::Token(sp, token::Pound), body]
380 .iter().cloned().collect::<TokenStream>().into()
388 #[derive(Clone, PartialEq)]
389 crate enum TokenType {
391 Keyword(keywords::Keyword),
400 fn to_string(&self) -> String {
402 TokenType::Token(ref t) => format!("`{}`", pprust::token_to_string(t)),
403 TokenType::Keyword(kw) => format!("`{}`", kw.name()),
404 TokenType::Operator => "an operator".to_string(),
405 TokenType::Lifetime => "lifetime".to_string(),
406 TokenType::Ident => "identifier".to_string(),
407 TokenType::Path => "path".to_string(),
408 TokenType::Type => "type".to_string(),
413 /// Returns true if `IDENT t` can start a type - `IDENT::a::b`, `IDENT<u8, u8>`,
414 /// `IDENT<<u8 as Trait>::AssocTy>`.
416 /// Types can also be of the form `IDENT(u8, u8) -> u8`, however this assumes
417 /// that IDENT is not the ident of a fn trait
418 fn can_continue_type_after_non_fn_ident(t: &token::Token) -> bool {
419 t == &token::ModSep || t == &token::Lt ||
420 t == &token::BinOp(token::Shl)
423 /// Information about the path to a module.
424 pub struct ModulePath {
427 pub result: Result<ModulePathSuccess, Error>,
430 pub struct ModulePathSuccess {
432 pub directory_ownership: DirectoryOwnership,
437 FileNotFoundForModule {
439 default_path: String,
440 secondary_path: String,
445 default_path: String,
446 secondary_path: String,
449 InclusiveRangeWithNoEnd,
453 fn span_err<S: Into<MultiSpan>>(self,
455 handler: &errors::Handler) -> DiagnosticBuilder {
457 Error::FileNotFoundForModule { ref mod_name,
461 let mut err = struct_span_err!(handler, sp, E0583,
462 "file not found for module `{}`", mod_name);
463 err.help(&format!("name the file either {} or {} inside the directory \"{}\"",
469 Error::DuplicatePaths { ref mod_name, ref default_path, ref secondary_path } => {
470 let mut err = struct_span_err!(handler, sp, E0584,
471 "file for module `{}` found at both {} and {}",
475 err.help("delete or rename one of them to remove the ambiguity");
478 Error::UselessDocComment => {
479 let mut err = struct_span_err!(handler, sp, E0585,
480 "found a documentation comment that doesn't document anything");
481 err.help("doc comments must come before what they document, maybe a comment was \
482 intended with `//`?");
485 Error::InclusiveRangeWithNoEnd => {
486 let mut err = struct_span_err!(handler, sp, E0586,
487 "inclusive range with no end");
488 err.help("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)");
498 AttributesParsed(ThinVec<Attribute>),
499 AlreadyParsed(P<Expr>),
502 impl From<Option<ThinVec<Attribute>>> for LhsExpr {
503 fn from(o: Option<ThinVec<Attribute>>) -> Self {
504 if let Some(attrs) = o {
505 LhsExpr::AttributesParsed(attrs)
507 LhsExpr::NotYetParsed
512 impl From<P<Expr>> for LhsExpr {
513 fn from(expr: P<Expr>) -> Self {
514 LhsExpr::AlreadyParsed(expr)
518 /// Create a placeholder argument.
519 fn dummy_arg(span: Span) -> Arg {
520 let ident = Ident::new(keywords::Invalid.name(), span);
522 id: ast::DUMMY_NODE_ID,
523 node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), ident, None),
529 id: ast::DUMMY_NODE_ID
531 Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID }
534 #[derive(Copy, Clone, Debug)]
535 enum TokenExpectType {
540 impl<'a> Parser<'a> {
541 pub fn new(sess: &'a ParseSess,
543 directory: Option<Directory<'a>>,
544 recurse_into_file_modules: bool,
545 desugar_doc_comments: bool)
547 let mut parser = Parser {
549 token: token::Whitespace,
550 span: syntax_pos::DUMMY_SP,
551 prev_span: syntax_pos::DUMMY_SP,
553 prev_token_kind: PrevTokenKind::Other,
554 restrictions: Restrictions::empty(),
555 recurse_into_file_modules,
556 directory: Directory {
557 path: Cow::from(PathBuf::new()),
558 ownership: DirectoryOwnership::Owned { relative: None }
560 root_module_name: None,
561 expected_tokens: Vec::new(),
562 token_cursor: TokenCursor {
563 frame: TokenCursorFrame::new(syntax_pos::DUMMY_SP, &Delimited {
564 delim: token::NoDelim,
569 desugar_doc_comments,
573 let tok = parser.next_tok();
574 parser.token = tok.tok;
575 parser.span = tok.sp;
577 if let Some(directory) = directory {
578 parser.directory = directory;
579 } else if !parser.span.is_dummy() {
580 if let FileName::Real(mut path) = sess.source_map().span_to_unmapped_path(parser.span) {
582 parser.directory.path = Cow::from(path);
586 parser.process_potential_macro_variable();
590 fn next_tok(&mut self) -> TokenAndSpan {
591 let mut next = if self.desugar_doc_comments {
592 self.token_cursor.next_desugared()
594 self.token_cursor.next()
596 if next.sp.is_dummy() {
597 // Tweak the location for better diagnostics, but keep syntactic context intact.
598 next.sp = self.prev_span.with_ctxt(next.sp.ctxt());
603 /// Convert the current token to a string using self's reader
604 pub fn this_token_to_string(&self) -> String {
605 pprust::token_to_string(&self.token)
608 fn token_descr(&self) -> Option<&'static str> {
609 Some(match &self.token {
610 t if t.is_special_ident() => "reserved identifier",
611 t if t.is_used_keyword() => "keyword",
612 t if t.is_unused_keyword() => "reserved keyword",
617 fn this_token_descr(&self) -> String {
618 if let Some(prefix) = self.token_descr() {
619 format!("{} `{}`", prefix, self.this_token_to_string())
621 format!("`{}`", self.this_token_to_string())
625 fn unexpected_last<T>(&self, t: &token::Token) -> PResult<'a, T> {
626 let token_str = pprust::token_to_string(t);
627 Err(self.span_fatal(self.prev_span, &format!("unexpected token: `{}`", token_str)))
630 crate fn unexpected<T>(&mut self) -> PResult<'a, T> {
631 match self.expect_one_of(&[], &[]) {
633 Ok(_) => unreachable!(),
637 /// Expect and consume the token t. Signal an error if
638 /// the next token is not t.
639 pub fn expect(&mut self, t: &token::Token) -> PResult<'a, ()> {
640 if self.expected_tokens.is_empty() {
641 if self.token == *t {
645 let token_str = pprust::token_to_string(t);
646 let this_token_str = self.this_token_to_string();
647 let mut err = self.fatal(&format!("expected `{}`, found `{}`",
651 let sp = if self.token == token::Token::Eof {
652 // EOF, don't want to point at the following char, but rather the last token
655 self.sess.source_map().next_point(self.prev_span)
657 let label_exp = format!("expected `{}`", token_str);
658 let cm = self.sess.source_map();
659 match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) {
660 (Ok(ref a), Ok(ref b)) if a.line == b.line => {
661 // When the spans are in the same line, it means that the only content
662 // between them is whitespace, point only at the found token.
663 err.span_label(self.span, label_exp);
666 err.span_label(sp, label_exp);
667 err.span_label(self.span, "unexpected token");
673 self.expect_one_of(slice::from_ref(t), &[])
677 /// Expect next token to be edible or inedible token. If edible,
678 /// then consume it; if inedible, then return without consuming
679 /// anything. Signal a fatal error if next token is unexpected.
680 fn expect_one_of(&mut self,
681 edible: &[token::Token],
682 inedible: &[token::Token]) -> PResult<'a, ()>{
683 fn tokens_to_string(tokens: &[TokenType]) -> String {
684 let mut i = tokens.iter();
685 // This might be a sign we need a connect method on Iterator.
687 .map_or("".to_string(), |t| t.to_string());
688 i.enumerate().fold(b, |mut b, (i, a)| {
689 if tokens.len() > 2 && i == tokens.len() - 2 {
691 } else if tokens.len() == 2 && i == tokens.len() - 2 {
696 b.push_str(&a.to_string());
700 if edible.contains(&self.token) {
703 } else if inedible.contains(&self.token) {
704 // leave it in the input
707 let mut expected = edible.iter()
708 .map(|x| TokenType::Token(x.clone()))
709 .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
710 .chain(self.expected_tokens.iter().cloned())
711 .collect::<Vec<_>>();
712 expected.sort_by_cached_key(|x| x.to_string());
714 let expect = tokens_to_string(&expected[..]);
715 let actual = self.this_token_to_string();
716 let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 {
717 let short_expect = if expected.len() > 6 {
718 format!("{} possible tokens", expected.len())
722 (format!("expected one of {}, found `{}`", expect, actual),
723 (self.sess.source_map().next_point(self.prev_span),
724 format!("expected one of {} here", short_expect)))
725 } else if expected.is_empty() {
726 (format!("unexpected token: `{}`", actual),
727 (self.prev_span, "unexpected token after this".to_string()))
729 (format!("expected {}, found `{}`", expect, actual),
730 (self.sess.source_map().next_point(self.prev_span),
731 format!("expected {} here", expect)))
733 let mut err = self.fatal(&msg_exp);
734 let sp = if self.token == token::Token::Eof {
735 // This is EOF, don't want to point at the following char, but rather the last token
741 let cm = self.sess.source_map();
742 match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) {
743 (Ok(ref a), Ok(ref b)) if a.line == b.line => {
744 // When the spans are in the same line, it means that the only content between
745 // them is whitespace, point at the found token in that case:
747 // X | () => { syntax error };
748 // | ^^^^^ expected one of 8 possible tokens here
750 // instead of having:
752 // X | () => { syntax error };
753 // | -^^^^^ unexpected token
755 // | expected one of 8 possible tokens here
756 err.span_label(self.span, label_exp);
759 err.span_label(sp, label_exp);
760 err.span_label(self.span, "unexpected token");
767 /// returns the span of expr, if it was not interpolated or the span of the interpolated token
768 fn interpolated_or_expr_span(&self,
769 expr: PResult<'a, P<Expr>>)
770 -> PResult<'a, (Span, P<Expr>)> {
772 if self.prev_token_kind == PrevTokenKind::Interpolated {
780 fn expected_ident_found(&self) -> DiagnosticBuilder<'a> {
781 let mut err = self.struct_span_err(self.span,
782 &format!("expected identifier, found {}",
783 self.this_token_descr()));
784 if let Some(token_descr) = self.token_descr() {
785 err.span_label(self.span, format!("expected identifier, found {}", token_descr));
787 err.span_label(self.span, "expected identifier");
788 if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) {
789 err.span_suggestion(self.span, "remove this comma", "".into());
795 pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
796 self.parse_ident_common(true)
799 fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
801 token::Ident(ident, _) => {
802 if self.token.is_reserved_ident() {
803 let mut err = self.expected_ident_found();
810 let span = self.span;
812 Ok(Ident::new(ident.name, span))
815 Err(if self.prev_token_kind == PrevTokenKind::DocComment {
816 self.span_fatal_err(self.prev_span, Error::UselessDocComment)
818 self.expected_ident_found()
824 /// Check if the next token is `tok`, and return `true` if so.
826 /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
828 crate fn check(&mut self, tok: &token::Token) -> bool {
829 let is_present = self.token == *tok;
830 if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
834 /// Consume token 'tok' if it exists. Returns true if the given
835 /// token was present, false otherwise.
836 pub fn eat(&mut self, tok: &token::Token) -> bool {
837 let is_present = self.check(tok);
838 if is_present { self.bump() }
842 fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
843 self.expected_tokens.push(TokenType::Keyword(kw));
844 self.token.is_keyword(kw)
847 /// If the next token is the given keyword, eat it and return
848 /// true. Otherwise, return false.
849 pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
850 if self.check_keyword(kw) {
858 fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
859 if self.token.is_keyword(kw) {
867 /// If the given word is not a keyword, signal an error.
868 /// If the next token is not the given word, signal an error.
869 /// Otherwise, eat it.
870 fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> {
871 if !self.eat_keyword(kw) {
878 fn check_ident(&mut self) -> bool {
879 if self.token.is_ident() {
882 self.expected_tokens.push(TokenType::Ident);
887 fn check_path(&mut self) -> bool {
888 if self.token.is_path_start() {
891 self.expected_tokens.push(TokenType::Path);
896 fn check_type(&mut self) -> bool {
897 if self.token.can_begin_type() {
900 self.expected_tokens.push(TokenType::Type);
905 /// Expect and consume a `+`. if `+=` is seen, replace it with a `=`
906 /// and continue. If a `+` is not seen, return false.
908 /// This is using when token splitting += into +.
909 /// See issue 47856 for an example of when this may occur.
910 fn eat_plus(&mut self) -> bool {
911 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
913 token::BinOp(token::Plus) => {
917 token::BinOpEq(token::Plus) => {
918 let span = self.span.with_lo(self.span.lo() + BytePos(1));
919 self.bump_with(token::Eq, span);
927 /// Checks to see if the next token is either `+` or `+=`.
928 /// Otherwise returns false.
929 fn check_plus(&mut self) -> bool {
930 if self.token.is_like_plus() {
934 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
939 /// Expect and consume an `&`. If `&&` is seen, replace it with a single
940 /// `&` and continue. If an `&` is not seen, signal an error.
941 fn expect_and(&mut self) -> PResult<'a, ()> {
942 self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
944 token::BinOp(token::And) => {
949 let span = self.span.with_lo(self.span.lo() + BytePos(1));
950 Ok(self.bump_with(token::BinOp(token::And), span))
952 _ => self.unexpected()
956 /// Expect and consume an `|`. If `||` is seen, replace it with a single
957 /// `|` and continue. If an `|` is not seen, signal an error.
958 fn expect_or(&mut self) -> PResult<'a, ()> {
959 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or)));
961 token::BinOp(token::Or) => {
966 let span = self.span.with_lo(self.span.lo() + BytePos(1));
967 Ok(self.bump_with(token::BinOp(token::Or), span))
969 _ => self.unexpected()
973 fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
975 None => {/* everything ok */}
977 let text = suf.as_str();
979 self.span_bug(sp, "found empty literal suffix in Some")
981 self.span_err(sp, &format!("{} with a suffix is invalid", kind));
986 /// Attempt to consume a `<`. If `<<` is seen, replace it with a single
987 /// `<` and continue. If a `<` is not seen, return false.
989 /// This is meant to be used when parsing generics on a path to get the
991 fn eat_lt(&mut self) -> bool {
992 self.expected_tokens.push(TokenType::Token(token::Lt));
998 token::BinOp(token::Shl) => {
999 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1000 self.bump_with(token::Lt, span);
1007 fn expect_lt(&mut self) -> PResult<'a, ()> {
1015 /// Expect and consume a GT. if a >> is seen, replace it
1016 /// with a single > and continue. If a GT is not seen,
1017 /// signal an error.
1018 fn expect_gt(&mut self) -> PResult<'a, ()> {
1019 self.expected_tokens.push(TokenType::Token(token::Gt));
1025 token::BinOp(token::Shr) => {
1026 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1027 Ok(self.bump_with(token::Gt, span))
1029 token::BinOpEq(token::Shr) => {
1030 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1031 Ok(self.bump_with(token::Ge, span))
1034 let span = self.span.with_lo(self.span.lo() + BytePos(1));
1035 Ok(self.bump_with(token::Eq, span))
1037 _ => self.unexpected()
1041 /// Eat and discard tokens until one of `kets` is encountered. Respects token trees,
1042 /// passes through any errors encountered. Used for error recovery.
1043 fn eat_to_tokens(&mut self, kets: &[&token::Token]) {
1044 let handler = self.diagnostic();
1046 if let Err(ref mut err) = self.parse_seq_to_before_tokens(kets,
1048 TokenExpectType::Expect,
1049 |p| Ok(p.parse_token_tree())) {
1050 handler.cancel(err);
1054 /// Parse a sequence, including the closing delimiter. The function
1055 /// f must consume tokens until reaching the next separator or
1056 /// closing bracket.
1057 pub fn parse_seq_to_end<T, F>(&mut self,
1061 -> PResult<'a, Vec<T>> where
1062 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1064 let val = self.parse_seq_to_before_end(ket, sep, f)?;
1069 /// Parse a sequence, not including the closing delimiter. The function
1070 /// f must consume tokens until reaching the next separator or
1071 /// closing bracket.
1072 pub fn parse_seq_to_before_end<T, F>(&mut self,
1076 -> PResult<'a, Vec<T>>
1077 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1079 self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
1082 fn parse_seq_to_before_tokens<T, F>(&mut self,
1083 kets: &[&token::Token],
1085 expect: TokenExpectType,
1087 -> PResult<'a, Vec<T>>
1088 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
1090 let mut first: bool = true;
1092 while !kets.iter().any(|k| {
1094 TokenExpectType::Expect => self.check(k),
1095 TokenExpectType::NoExpect => self.token == **k,
1099 token::CloseDelim(..) | token::Eof => break,
1102 if let Some(ref t) = sep.sep {
1106 if let Err(mut e) = self.expect(t) {
1107 // Attempt to keep parsing if it was a similar separator
1108 if let Some(ref tokens) = t.similar_tokens() {
1109 if tokens.contains(&self.token) {
1114 // Attempt to keep parsing if it was an omitted separator
1128 if sep.trailing_sep_allowed && kets.iter().any(|k| {
1130 TokenExpectType::Expect => self.check(k),
1131 TokenExpectType::NoExpect => self.token == **k,
1144 /// Parse a sequence, including the closing delimiter. The function
1145 /// f must consume tokens until reaching the next separator or
1146 /// closing bracket.
1147 fn parse_unspanned_seq<T, F>(&mut self,
1152 -> PResult<'a, Vec<T>> where
1153 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1156 let result = self.parse_seq_to_before_end(ket, sep, f)?;
1157 if self.token == *ket {
1163 /// Advance the parser by one token
1164 pub fn bump(&mut self) {
1165 if self.prev_token_kind == PrevTokenKind::Eof {
1166 // Bumping after EOF is a bad sign, usually an infinite loop.
1167 self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
1170 self.prev_span = self.meta_var_span.take().unwrap_or(self.span);
1172 // Record last token kind for possible error recovery.
1173 self.prev_token_kind = match self.token {
1174 token::DocComment(..) => PrevTokenKind::DocComment,
1175 token::Comma => PrevTokenKind::Comma,
1176 token::BinOp(token::Plus) => PrevTokenKind::Plus,
1177 token::Interpolated(..) => PrevTokenKind::Interpolated,
1178 token::Eof => PrevTokenKind::Eof,
1179 token::Ident(..) => PrevTokenKind::Ident,
1180 _ => PrevTokenKind::Other,
1183 let next = self.next_tok();
1184 self.span = next.sp;
1185 self.token = next.tok;
1186 self.expected_tokens.clear();
1187 // check after each token
1188 self.process_potential_macro_variable();
1191 /// Advance the parser using provided token as a next one. Use this when
1192 /// consuming a part of a token. For example a single `<` from `<<`.
1193 fn bump_with(&mut self, next: token::Token, span: Span) {
1194 self.prev_span = self.span.with_hi(span.lo());
1195 // It would be incorrect to record the kind of the current token, but
1196 // fortunately for tokens currently using `bump_with`, the
1197 // prev_token_kind will be of no use anyway.
1198 self.prev_token_kind = PrevTokenKind::Other;
1201 self.expected_tokens.clear();
1204 pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where
1205 F: FnOnce(&token::Token) -> R,
1208 return f(&self.token)
1211 f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1212 Some(tree) => match tree {
1213 TokenTree::Token(_, tok) => tok,
1214 TokenTree::Delimited(_, delimited) => token::OpenDelim(delimited.delim),
1216 None => token::CloseDelim(self.token_cursor.frame.delim),
1220 fn look_ahead_span(&self, dist: usize) -> Span {
1225 match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1226 Some(TokenTree::Token(span, _)) | Some(TokenTree::Delimited(span, _)) => span,
1227 None => self.look_ahead_span(dist - 1),
1230 pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
1231 self.sess.span_diagnostic.struct_span_fatal(self.span, m)
1233 pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1234 self.sess.span_diagnostic.struct_span_fatal(sp, m)
1236 fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> {
1237 err.span_err(sp, self.diagnostic())
1239 fn bug(&self, m: &str) -> ! {
1240 self.sess.span_diagnostic.span_bug(self.span, m)
1242 fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
1243 self.sess.span_diagnostic.span_err(sp, m)
1245 fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
1246 self.sess.span_diagnostic.struct_span_err(sp, m)
1248 crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
1249 self.sess.span_diagnostic.span_bug(sp, m)
1251 crate fn abort_if_errors(&self) {
1252 self.sess.span_diagnostic.abort_if_errors();
1255 fn cancel(&self, err: &mut DiagnosticBuilder) {
1256 self.sess.span_diagnostic.cancel(err)
1259 crate fn diagnostic(&self) -> &'a errors::Handler {
1260 &self.sess.span_diagnostic
1263 /// Is the current token one of the keywords that signals a bare function
1265 fn token_is_bare_fn_keyword(&mut self) -> bool {
1266 self.check_keyword(keywords::Fn) ||
1267 self.check_keyword(keywords::Unsafe) ||
1268 self.check_keyword(keywords::Extern) && self.is_extern_non_path()
1271 /// parse a TyKind::BareFn type:
1272 fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
1275 [unsafe] [extern "ABI"] fn (S) -> T
1285 let unsafety = self.parse_unsafety();
1286 let abi = if self.eat_keyword(keywords::Extern) {
1287 self.parse_opt_abi()?.unwrap_or(Abi::C)
1292 self.expect_keyword(keywords::Fn)?;
1293 let (inputs, variadic) = self.parse_fn_args(false, true)?;
1294 let ret_ty = self.parse_ret_ty(false)?;
1295 let decl = P(FnDecl {
1300 Ok(TyKind::BareFn(P(BareFnTy {
1308 /// Parse asyncness: `async` or nothing
1309 fn parse_asyncness(&mut self) -> IsAsync {
1310 if self.eat_keyword(keywords::Async) {
1312 closure_id: ast::DUMMY_NODE_ID,
1313 return_impl_trait_id: ast::DUMMY_NODE_ID,
1320 /// Parse unsafety: `unsafe` or nothing.
1321 fn parse_unsafety(&mut self) -> Unsafety {
1322 if self.eat_keyword(keywords::Unsafe) {
1329 /// Parse the items in a trait declaration
1330 pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> {
1331 maybe_whole!(self, NtTraitItem, |x| x);
1332 let attrs = self.parse_outer_attributes()?;
1333 let (mut item, tokens) = self.collect_tokens(|this| {
1334 this.parse_trait_item_(at_end, attrs)
1336 // See `parse_item` for why this clause is here.
1337 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
1338 item.tokens = Some(tokens);
1343 fn parse_trait_item_(&mut self,
1345 mut attrs: Vec<Attribute>) -> PResult<'a, TraitItem> {
1348 let (name, node, generics) = if self.eat_keyword(keywords::Type) {
1349 self.parse_trait_item_assoc_ty()?
1350 } else if self.is_const_item() {
1351 self.expect_keyword(keywords::Const)?;
1352 let ident = self.parse_ident()?;
1353 self.expect(&token::Colon)?;
1354 let ty = self.parse_ty()?;
1355 let default = if self.check(&token::Eq) {
1357 let expr = self.parse_expr()?;
1358 self.expect(&token::Semi)?;
1361 self.expect(&token::Semi)?;
1364 (ident, TraitItemKind::Const(ty, default), ast::Generics::default())
1365 } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
1366 // trait item macro.
1367 (keywords::Invalid.ident(), ast::TraitItemKind::Macro(mac), ast::Generics::default())
1369 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
1371 let ident = self.parse_ident()?;
1372 let mut generics = self.parse_generics()?;
1374 let d = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
1375 // This is somewhat dubious; We don't want to allow
1376 // argument names to be left off if there is a
1378 p.parse_arg_general(false)
1380 generics.where_clause = self.parse_where_clause()?;
1382 let sig = ast::MethodSig {
1392 let body = match self.token {
1396 debug!("parse_trait_methods(): parsing required method");
1399 token::OpenDelim(token::Brace) => {
1400 debug!("parse_trait_methods(): parsing provided method");
1402 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1403 attrs.extend(inner_attrs.iter().cloned());
1407 let token_str = self.this_token_to_string();
1408 let mut err = self.fatal(&format!("expected `;` or `{{`, found `{}`",
1410 err.span_label(self.span, "expected `;` or `{`");
1414 (ident, ast::TraitItemKind::Method(sig, body), generics)
1418 id: ast::DUMMY_NODE_ID,
1423 span: lo.to(self.prev_span),
1428 /// Parse optional return type [ -> TY ] in function decl
1429 fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> {
1430 if self.eat(&token::RArrow) {
1431 Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true)?))
1433 Ok(FunctionRetTy::Default(self.span.shrink_to_lo()))
1438 pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
1439 self.parse_ty_common(true, true)
1442 /// Parse a type in restricted contexts where `+` is not permitted.
1443 /// Example 1: `&'a TYPE`
1444 /// `+` is prohibited to maintain operator priority (P(+) < P(&)).
1445 /// Example 2: `value1 as TYPE + value2`
1446 /// `+` is prohibited to avoid interactions with expression grammar.
1447 fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
1448 self.parse_ty_common(false, true)
1451 fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool)
1452 -> PResult<'a, P<Ty>> {
1453 maybe_whole!(self, NtTy, |x| x);
1456 let mut impl_dyn_multi = false;
1457 let node = if self.eat(&token::OpenDelim(token::Paren)) {
1458 // `(TYPE)` is a parenthesized type.
1459 // `(TYPE,)` is a tuple with a single field of type TYPE.
1460 let mut ts = vec![];
1461 let mut last_comma = false;
1462 while self.token != token::CloseDelim(token::Paren) {
1463 ts.push(self.parse_ty()?);
1464 if self.eat(&token::Comma) {
1471 let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
1472 self.expect(&token::CloseDelim(token::Paren))?;
1474 if ts.len() == 1 && !last_comma {
1475 let ty = ts.into_iter().nth(0).unwrap().into_inner();
1476 let maybe_bounds = allow_plus && self.token.is_like_plus();
1478 // `(TY_BOUND_NOPAREN) + BOUND + ...`.
1479 TyKind::Path(None, ref path) if maybe_bounds => {
1480 self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
1482 TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
1483 if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
1484 let path = match bounds[0] {
1485 GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
1486 _ => self.bug("unexpected lifetime bound"),
1488 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1491 _ => TyKind::Paren(P(ty))
1496 } else if self.eat(&token::Not) {
1499 } else if self.eat(&token::BinOp(token::Star)) {
1501 TyKind::Ptr(self.parse_ptr()?)
1502 } else if self.eat(&token::OpenDelim(token::Bracket)) {
1504 let t = self.parse_ty()?;
1505 // Parse optional `; EXPR` in `[TYPE; EXPR]`
1506 let t = match self.maybe_parse_fixed_length_of_vec()? {
1507 None => TyKind::Slice(t),
1508 Some(length) => TyKind::Array(t, AnonConst {
1509 id: ast::DUMMY_NODE_ID,
1513 self.expect(&token::CloseDelim(token::Bracket))?;
1515 } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
1518 self.parse_borrowed_pointee()?
1519 } else if self.eat_keyword_noexpect(keywords::Typeof) {
1521 // In order to not be ambiguous, the type must be surrounded by parens.
1522 self.expect(&token::OpenDelim(token::Paren))?;
1524 id: ast::DUMMY_NODE_ID,
1525 value: self.parse_expr()?,
1527 self.expect(&token::CloseDelim(token::Paren))?;
1529 } else if self.eat_keyword(keywords::Underscore) {
1530 // A type to be inferred `_`
1532 } else if self.token_is_bare_fn_keyword() {
1533 // Function pointer type
1534 self.parse_ty_bare_fn(Vec::new())?
1535 } else if self.check_keyword(keywords::For) {
1536 // Function pointer type or bound list (trait object type) starting with a poly-trait.
1537 // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
1538 // `for<'lt> Trait1<'lt> + Trait2 + 'a`
1540 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
1541 if self.token_is_bare_fn_keyword() {
1542 self.parse_ty_bare_fn(lifetime_defs)?
1544 let path = self.parse_path(PathStyle::Type)?;
1545 let parse_plus = allow_plus && self.check_plus();
1546 self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
1548 } else if self.eat_keyword(keywords::Impl) {
1549 // Always parse bounds greedily for better error recovery.
1550 let bounds = self.parse_generic_bounds()?;
1551 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1552 TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
1553 } else if self.check_keyword(keywords::Dyn) &&
1554 self.look_ahead(1, |t| t.can_begin_bound() &&
1555 !can_continue_type_after_non_fn_ident(t)) {
1556 self.bump(); // `dyn`
1557 // Always parse bounds greedily for better error recovery.
1558 let bounds = self.parse_generic_bounds()?;
1559 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1560 TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
1561 } else if self.check(&token::Question) ||
1562 self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
1563 // Bound list (trait object type)
1564 TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus)?,
1565 TraitObjectSyntax::None)
1566 } else if self.eat_lt() {
1568 let (qself, path) = self.parse_qpath(PathStyle::Type)?;
1569 TyKind::Path(Some(qself), path)
1570 } else if self.token.is_path_start() {
1572 let path = self.parse_path(PathStyle::Type)?;
1573 if self.eat(&token::Not) {
1574 // Macro invocation in type position
1575 let (delim, tts) = self.expect_delimited_token_tree()?;
1576 let node = Mac_ { path, tts, delim };
1577 TyKind::Mac(respan(lo.to(self.prev_span), node))
1579 // Just a type path or bound list (trait object type) starting with a trait.
1581 // `Trait1 + Trait2 + 'a`
1582 if allow_plus && self.check_plus() {
1583 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1585 TyKind::Path(None, path)
1589 let msg = format!("expected type, found {}", self.this_token_descr());
1590 return Err(self.fatal(&msg));
1593 let span = lo.to(self.prev_span);
1594 let ty = Ty { node, span, id: ast::DUMMY_NODE_ID };
1596 // Try to recover from use of `+` with incorrect priority.
1597 self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
1598 self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
1599 let ty = self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)?;
1604 fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
1605 lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
1606 let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));
1607 let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
1609 self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
1610 bounds.append(&mut self.parse_generic_bounds()?);
1612 Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
1615 fn maybe_report_ambiguous_plus(&mut self, allow_plus: bool, impl_dyn_multi: bool, ty: &Ty) {
1616 if !allow_plus && impl_dyn_multi {
1617 let sum_with_parens = format!("({})", pprust::ty_to_string(&ty));
1618 self.struct_span_err(ty.span, "ambiguous `+` in a type")
1619 .span_suggestion_with_applicability(
1621 "use parentheses to disambiguate",
1623 Applicability::MachineApplicable
1628 fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> {
1629 // Do not add `+` to expected tokens.
1630 if !allow_plus || !self.token.is_like_plus() {
1635 let bounds = self.parse_generic_bounds()?;
1636 let sum_span = ty.span.to(self.prev_span);
1638 let mut err = struct_span_err!(self.sess.span_diagnostic, sum_span, E0178,
1639 "expected a path on the left-hand side of `+`, not `{}`", pprust::ty_to_string(ty));
1642 TyKind::Rptr(ref lifetime, ref mut_ty) => {
1643 let sum_with_parens = pprust::to_string(|s| {
1644 use print::pprust::PrintState;
1647 s.print_opt_lifetime(lifetime)?;
1648 s.print_mutability(mut_ty.mutbl)?;
1650 s.print_type(&mut_ty.ty)?;
1651 s.print_type_bounds(" +", &bounds)?;
1654 err.span_suggestion_with_applicability(
1656 "try adding parentheses",
1658 Applicability::MachineApplicable
1661 TyKind::Ptr(..) | TyKind::BareFn(..) => {
1662 err.span_label(sum_span, "perhaps you forgot parentheses?");
1665 err.span_label(sum_span, "expected a path");
1672 // Try to recover from associated item paths like `[T]::AssocItem`/`(T, U)::AssocItem`.
1673 fn maybe_recover_from_bad_qpath<T: RecoverQPath>(&mut self, base: T, allow_recovery: bool)
1675 // Do not add `::` to expected tokens.
1676 if !allow_recovery || self.token != token::ModSep {
1679 let ty = match base.to_ty() {
1681 None => return Ok(base),
1684 self.bump(); // `::`
1685 let mut segments = Vec::new();
1686 self.parse_path_segments(&mut segments, T::PATH_STYLE, true)?;
1688 let span = ty.span.to(self.prev_span);
1689 let path_span = span.to(span); // use an empty path since `position` == 0
1690 let recovered = base.to_recovered(
1691 Some(QSelf { ty, path_span, position: 0 }),
1692 ast::Path { segments, span },
1696 .struct_span_err(span, "missing angle brackets in associated item path")
1697 .span_suggestion_with_applicability( // this is a best-effort recovery
1698 span, "try", recovered.to_string(), Applicability::MaybeIncorrect
1704 fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
1705 let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
1706 let mutbl = self.parse_mutability();
1707 let ty = self.parse_ty_no_plus()?;
1708 return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl }));
1711 fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
1712 let mutbl = if self.eat_keyword(keywords::Mut) {
1714 } else if self.eat_keyword(keywords::Const) {
1715 Mutability::Immutable
1717 let span = self.prev_span;
1719 "expected mut or const in raw pointer type (use \
1720 `*mut T` or `*const T` as appropriate)");
1721 Mutability::Immutable
1723 let t = self.parse_ty_no_plus()?;
1724 Ok(MutTy { ty: t, mutbl: mutbl })
1727 fn is_named_argument(&mut self) -> bool {
1728 let offset = match self.token {
1729 token::Interpolated(ref nt) => match nt.0 {
1730 token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
1733 token::BinOp(token::And) | token::AndAnd => 1,
1734 _ if self.token.is_keyword(keywords::Mut) => 1,
1738 self.look_ahead(offset, |t| t.is_ident()) &&
1739 self.look_ahead(offset + 1, |t| t == &token::Colon)
1742 /// This version of parse arg doesn't necessarily require
1743 /// identifier names.
1744 fn parse_arg_general(&mut self, require_name: bool) -> PResult<'a, Arg> {
1745 maybe_whole!(self, NtArg, |x| x);
1747 let (pat, ty) = if require_name || self.is_named_argument() {
1748 debug!("parse_arg_general parse_pat (require_name:{})",
1750 let pat = self.parse_pat()?;
1752 self.expect(&token::Colon)?;
1753 (pat, self.parse_ty()?)
1755 debug!("parse_arg_general ident_to_pat");
1757 let parser_snapshot_before_pat = self.clone();
1759 // We're going to try parsing the argument as a pattern (even though it's not
1760 // allowed). This way we can provide better errors to the user.
1761 let pat_arg: PResult<'a, _> = do catch {
1762 let pat = self.parse_pat()?;
1763 self.expect(&token::Colon)?;
1764 (pat, self.parse_ty()?)
1769 let mut err = self.diagnostic().struct_span_err_with_code(
1771 "patterns aren't allowed in methods without bodies",
1772 DiagnosticId::Error("E0642".into()),
1774 err.span_suggestion_short_with_applicability(
1776 "give this argument a name or use an underscore to ignore it",
1778 Applicability::MachineApplicable,
1781 // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
1783 node: PatKind::Wild,
1785 id: ast::DUMMY_NODE_ID
1791 // Recover from attempting to parse the argument as a pattern. This means
1792 // the type is alone, with no name, e.g. `fn foo(u32)`.
1793 mem::replace(self, parser_snapshot_before_pat);
1794 debug!("parse_arg_general ident_to_pat");
1795 let ident = Ident::new(keywords::Invalid.name(), self.prev_span);
1796 let ty = self.parse_ty()?;
1798 id: ast::DUMMY_NODE_ID,
1799 node: PatKind::Ident(
1800 BindingMode::ByValue(Mutability::Immutable), ident, None),
1808 Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID })
1811 /// Parse a single function argument
1812 crate fn parse_arg(&mut self) -> PResult<'a, Arg> {
1813 self.parse_arg_general(true)
1816 /// Parse an argument in a lambda header e.g. |arg, arg|
1817 fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
1818 let pat = self.parse_pat()?;
1819 let t = if self.eat(&token::Colon) {
1823 id: ast::DUMMY_NODE_ID,
1824 node: TyKind::Infer,
1831 id: ast::DUMMY_NODE_ID
1835 fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
1836 if self.eat(&token::Semi) {
1837 Ok(Some(self.parse_expr()?))
1843 /// Matches token_lit = LIT_INTEGER | ...
1844 fn parse_lit_token(&mut self) -> PResult<'a, LitKind> {
1845 let out = match self.token {
1846 token::Interpolated(ref nt) => match nt.0 {
1847 token::NtExpr(ref v) | token::NtLiteral(ref v) => match v.node {
1848 ExprKind::Lit(ref lit) => { lit.node.clone() }
1849 _ => { return self.unexpected_last(&self.token); }
1851 _ => { return self.unexpected_last(&self.token); }
1853 token::Literal(lit, suf) => {
1854 let diag = Some((self.span, &self.sess.span_diagnostic));
1855 let (suffix_illegal, result) = parse::lit_token(lit, suf, diag);
1859 self.expect_no_suffix(sp, &format!("{} literal", lit.short_name()), suf)
1864 _ => { return self.unexpected_last(&self.token); }
1871 /// Matches lit = true | false | token_lit
1872 crate fn parse_lit(&mut self) -> PResult<'a, Lit> {
1874 let lit = if self.eat_keyword(keywords::True) {
1876 } else if self.eat_keyword(keywords::False) {
1877 LitKind::Bool(false)
1879 let lit = self.parse_lit_token()?;
1882 Ok(source_map::Spanned { node: lit, span: lo.to(self.prev_span) })
1885 /// matches '-' lit | lit (cf. ast_validation::AstValidator::check_expr_within_pat)
1886 crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
1887 maybe_whole_expr!(self);
1889 let minus_lo = self.span;
1890 let minus_present = self.eat(&token::BinOp(token::Minus));
1892 let literal = P(self.parse_lit()?);
1893 let hi = self.prev_span;
1894 let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
1897 let minus_hi = self.prev_span;
1898 let unary = self.mk_unary(UnOp::Neg, expr);
1899 Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
1905 fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
1907 token::Ident(ident, _) if self.token.is_path_segment_keyword() => {
1908 let span = self.span;
1910 Ok(Ident::new(ident.name, span))
1912 _ => self.parse_ident(),
1916 /// Parses qualified path.
1917 /// Assumes that the leading `<` has been parsed already.
1919 /// `qualified_path = <type [as trait_ref]>::path`
1924 /// `<T as U>::F::a<S>` (without disambiguator)
1925 /// `<T as U>::F::a::<S>` (with disambiguator)
1926 fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::Path)> {
1927 let lo = self.prev_span;
1928 let ty = self.parse_ty()?;
1930 // `path` will contain the prefix of the path up to the `>`,
1931 // if any (e.g., `U` in the `<T as U>::*` examples
1932 // above). `path_span` has the span of that path, or an empty
1933 // span in the case of something like `<T>::Bar`.
1934 let (mut path, path_span);
1935 if self.eat_keyword(keywords::As) {
1936 let path_lo = self.span;
1937 path = self.parse_path(PathStyle::Type)?;
1938 path_span = path_lo.to(self.prev_span);
1940 path = ast::Path { segments: Vec::new(), span: syntax_pos::DUMMY_SP };
1941 path_span = self.span.to(self.span);
1944 self.expect(&token::Gt)?;
1945 self.expect(&token::ModSep)?;
1947 let qself = QSelf { ty, path_span, position: path.segments.len() };
1948 self.parse_path_segments(&mut path.segments, style, true)?;
1950 Ok((qself, ast::Path { segments: path.segments, span: lo.to(self.prev_span) }))
1953 /// Parses simple paths.
1955 /// `path = [::] segment+`
1956 /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
1959 /// `a::b::C<D>` (without disambiguator)
1960 /// `a::b::C::<D>` (with disambiguator)
1961 /// `Fn(Args)` (without disambiguator)
1962 /// `Fn::(Args)` (with disambiguator)
1963 pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
1964 self.parse_path_common(style, true)
1967 crate fn parse_path_common(&mut self, style: PathStyle, enable_warning: bool)
1968 -> PResult<'a, ast::Path> {
1969 maybe_whole!(self, NtPath, |path| {
1970 if style == PathStyle::Mod &&
1971 path.segments.iter().any(|segment| segment.args.is_some()) {
1972 self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
1977 let lo = self.meta_var_span.unwrap_or(self.span);
1978 let mut segments = Vec::new();
1979 if self.eat(&token::ModSep) {
1980 segments.push(PathSegment::crate_root(lo.shrink_to_lo()));
1982 self.parse_path_segments(&mut segments, style, enable_warning)?;
1984 Ok(ast::Path { segments, span: lo.to(self.prev_span) })
1987 /// Like `parse_path`, but also supports parsing `Word` meta items into paths for back-compat.
1988 /// This is used when parsing derive macro paths in `#[derive]` attributes.
1989 pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
1990 let meta_ident = match self.token {
1991 token::Interpolated(ref nt) => match nt.0 {
1992 token::NtMeta(ref meta) => match meta.node {
1993 ast::MetaItemKind::Word => Some(meta.ident.clone()),
2000 if let Some(path) = meta_ident {
2004 self.parse_path(style)
2007 fn parse_path_segments(&mut self,
2008 segments: &mut Vec<PathSegment>,
2010 enable_warning: bool)
2011 -> PResult<'a, ()> {
2013 segments.push(self.parse_path_segment(style, enable_warning)?);
2015 if self.is_import_coupler() || !self.eat(&token::ModSep) {
2021 fn parse_path_segment(&mut self, style: PathStyle, enable_warning: bool)
2022 -> PResult<'a, PathSegment> {
2023 let ident = self.parse_path_segment_ident()?;
2025 let is_args_start = |token: &token::Token| match *token {
2026 token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren) => true,
2029 let check_args_start = |this: &mut Self| {
2030 this.expected_tokens.extend_from_slice(
2031 &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
2033 is_args_start(&this.token)
2036 Ok(if style == PathStyle::Type && check_args_start(self) ||
2037 style != PathStyle::Mod && self.check(&token::ModSep)
2038 && self.look_ahead(1, |t| is_args_start(t)) {
2039 // Generic arguments are found - `<`, `(`, `::<` or `::(`.
2041 if self.eat(&token::ModSep) && style == PathStyle::Type && enable_warning {
2042 self.diagnostic().struct_span_warn(self.prev_span, "unnecessary path disambiguator")
2043 .span_label(self.prev_span, "try removing `::`").emit();
2046 let args = if self.eat_lt() {
2048 let (args, bindings) = self.parse_generic_args()?;
2050 let span = lo.to(self.prev_span);
2051 AngleBracketedArgs { args, bindings, span }.into()
2055 let inputs = self.parse_seq_to_before_tokens(
2056 &[&token::CloseDelim(token::Paren)],
2057 SeqSep::trailing_allowed(token::Comma),
2058 TokenExpectType::Expect,
2061 let output = if self.eat(&token::RArrow) {
2062 Some(self.parse_ty_common(false, false)?)
2066 let span = lo.to(self.prev_span);
2067 ParenthesisedArgs { inputs, output, span }.into()
2070 PathSegment { ident, args }
2072 // Generic arguments are not found.
2073 PathSegment::from_ident(ident)
2077 crate fn check_lifetime(&mut self) -> bool {
2078 self.expected_tokens.push(TokenType::Lifetime);
2079 self.token.is_lifetime()
2082 /// Parse single lifetime 'a or panic.
2083 crate fn expect_lifetime(&mut self) -> Lifetime {
2084 if let Some(ident) = self.token.lifetime() {
2085 let span = self.span;
2087 Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
2089 self.span_bug(self.span, "not a lifetime")
2093 fn eat_label(&mut self) -> Option<Label> {
2094 if let Some(ident) = self.token.lifetime() {
2095 let span = self.span;
2097 Some(Label { ident: Ident::new(ident.name, span) })
2103 /// Parse mutability (`mut` or nothing).
2104 fn parse_mutability(&mut self) -> Mutability {
2105 if self.eat_keyword(keywords::Mut) {
2108 Mutability::Immutable
2112 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
2113 if let token::Literal(token::Integer(name), None) = self.token {
2115 Ok(Ident::new(name, self.prev_span))
2117 self.parse_ident_common(false)
2121 /// Parse ident (COLON expr)?
2122 fn parse_field(&mut self) -> PResult<'a, Field> {
2123 let attrs = self.parse_outer_attributes()?;
2126 // Check if a colon exists one ahead. This means we're parsing a fieldname.
2127 let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
2128 let fieldname = self.parse_field_name()?;
2130 (fieldname, self.parse_expr()?, false)
2132 let fieldname = self.parse_ident_common(false)?;
2134 // Mimic `x: x` for the `x` field shorthand.
2135 let path = ast::Path::from_ident(fieldname);
2136 let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
2137 (fieldname, expr, true)
2141 span: lo.to(expr.span),
2144 attrs: attrs.into(),
2148 fn mk_expr(&mut self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
2149 P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID })
2152 fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
2153 ExprKind::Unary(unop, expr)
2156 fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2157 ExprKind::Binary(binop, lhs, rhs)
2160 fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
2161 ExprKind::Call(f, args)
2164 fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
2165 ExprKind::Index(expr, idx)
2168 fn mk_range(&mut self,
2169 start: Option<P<Expr>>,
2170 end: Option<P<Expr>>,
2171 limits: RangeLimits)
2172 -> PResult<'a, ast::ExprKind> {
2173 if end.is_none() && limits == RangeLimits::Closed {
2174 Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd))
2176 Ok(ExprKind::Range(start, end, limits))
2180 fn mk_assign_op(&mut self, binop: ast::BinOp,
2181 lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
2182 ExprKind::AssignOp(binop, lhs, rhs)
2185 pub fn mk_mac_expr(&mut self, span: Span, m: Mac_, attrs: ThinVec<Attribute>) -> P<Expr> {
2187 id: ast::DUMMY_NODE_ID,
2188 node: ExprKind::Mac(source_map::Spanned {node: m, span: span}),
2194 fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, ThinTokenStream)> {
2195 let delim = match self.token {
2196 token::OpenDelim(delim) => delim,
2198 let msg = "expected open delimiter";
2199 let mut err = self.fatal(msg);
2200 err.span_label(self.span, msg);
2204 let delimited = match self.parse_token_tree() {
2205 TokenTree::Delimited(_, delimited) => delimited,
2206 _ => unreachable!(),
2208 let delim = match delim {
2209 token::Paren => MacDelimiter::Parenthesis,
2210 token::Bracket => MacDelimiter::Bracket,
2211 token::Brace => MacDelimiter::Brace,
2212 token::NoDelim => self.bug("unexpected no delimiter"),
2214 Ok((delim, delimited.stream().into()))
2217 /// At the bottom (top?) of the precedence hierarchy,
2218 /// parse things like parenthesized exprs,
2219 /// macros, return, etc.
2221 /// NB: This does not parse outer attributes,
2222 /// and is private because it only works
2223 /// correctly if called from parse_dot_or_call_expr().
2224 fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
2225 maybe_whole_expr!(self);
2227 // Outer attributes are already parsed and will be
2228 // added to the return value after the fact.
2230 // Therefore, prevent sub-parser from parsing
2231 // attributes by giving them a empty "already parsed" list.
2232 let mut attrs = ThinVec::new();
2235 let mut hi = self.span;
2239 // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2241 token::OpenDelim(token::Paren) => {
2244 attrs.extend(self.parse_inner_attributes()?);
2246 // (e) is parenthesized e
2247 // (e,) is a tuple with only one field, e
2248 let mut es = vec![];
2249 let mut trailing_comma = false;
2250 while self.token != token::CloseDelim(token::Paren) {
2251 es.push(self.parse_expr()?);
2252 self.expect_one_of(&[], &[token::Comma, token::CloseDelim(token::Paren)])?;
2253 if self.check(&token::Comma) {
2254 trailing_comma = true;
2258 trailing_comma = false;
2264 hi = self.prev_span;
2265 ex = if es.len() == 1 && !trailing_comma {
2266 ExprKind::Paren(es.into_iter().nth(0).unwrap())
2271 token::OpenDelim(token::Brace) => {
2272 return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
2274 token::BinOp(token::Or) | token::OrOr => {
2275 return self.parse_lambda_expr(attrs);
2277 token::OpenDelim(token::Bracket) => {
2280 attrs.extend(self.parse_inner_attributes()?);
2282 if self.check(&token::CloseDelim(token::Bracket)) {
2285 ex = ExprKind::Array(Vec::new());
2288 let first_expr = self.parse_expr()?;
2289 if self.check(&token::Semi) {
2290 // Repeating array syntax: [ 0; 512 ]
2292 let count = AnonConst {
2293 id: ast::DUMMY_NODE_ID,
2294 value: self.parse_expr()?,
2296 self.expect(&token::CloseDelim(token::Bracket))?;
2297 ex = ExprKind::Repeat(first_expr, count);
2298 } else if self.check(&token::Comma) {
2299 // Vector with two or more elements.
2301 let remaining_exprs = self.parse_seq_to_end(
2302 &token::CloseDelim(token::Bracket),
2303 SeqSep::trailing_allowed(token::Comma),
2304 |p| Ok(p.parse_expr()?)
2306 let mut exprs = vec![first_expr];
2307 exprs.extend(remaining_exprs);
2308 ex = ExprKind::Array(exprs);
2310 // Vector with one element.
2311 self.expect(&token::CloseDelim(token::Bracket))?;
2312 ex = ExprKind::Array(vec![first_expr]);
2315 hi = self.prev_span;
2319 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
2321 return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
2323 if self.span.edition() >= Edition::Edition2018 &&
2324 self.check_keyword(keywords::Async)
2326 if self.is_async_block() { // check for `async {` and `async move {`
2327 return self.parse_async_block(attrs);
2329 return self.parse_lambda_expr(attrs);
2332 if self.check_keyword(keywords::Move) || self.check_keyword(keywords::Static) {
2333 return self.parse_lambda_expr(attrs);
2335 if self.eat_keyword(keywords::If) {
2336 return self.parse_if_expr(attrs);
2338 if self.eat_keyword(keywords::For) {
2339 let lo = self.prev_span;
2340 return self.parse_for_expr(None, lo, attrs);
2342 if self.eat_keyword(keywords::While) {
2343 let lo = self.prev_span;
2344 return self.parse_while_expr(None, lo, attrs);
2346 if let Some(label) = self.eat_label() {
2347 let lo = label.ident.span;
2348 self.expect(&token::Colon)?;
2349 if self.eat_keyword(keywords::While) {
2350 return self.parse_while_expr(Some(label), lo, attrs)
2352 if self.eat_keyword(keywords::For) {
2353 return self.parse_for_expr(Some(label), lo, attrs)
2355 if self.eat_keyword(keywords::Loop) {
2356 return self.parse_loop_expr(Some(label), lo, attrs)
2358 if self.token == token::OpenDelim(token::Brace) {
2359 return self.parse_block_expr(Some(label),
2361 BlockCheckMode::Default,
2364 let msg = "expected `while`, `for`, `loop` or `{` after a label";
2365 let mut err = self.fatal(msg);
2366 err.span_label(self.span, msg);
2369 if self.eat_keyword(keywords::Loop) {
2370 let lo = self.prev_span;
2371 return self.parse_loop_expr(None, lo, attrs);
2373 if self.eat_keyword(keywords::Continue) {
2374 let label = self.eat_label();
2375 let ex = ExprKind::Continue(label);
2376 let hi = self.prev_span;
2377 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2379 if self.eat_keyword(keywords::Match) {
2380 return self.parse_match_expr(attrs);
2382 if self.eat_keyword(keywords::Unsafe) {
2383 return self.parse_block_expr(
2386 BlockCheckMode::Unsafe(ast::UserProvided),
2389 if self.is_catch_expr() {
2391 assert!(self.eat_keyword(keywords::Do));
2392 assert!(self.eat_keyword(keywords::Catch));
2393 return self.parse_catch_expr(lo, attrs);
2395 if self.eat_keyword(keywords::Return) {
2396 if self.token.can_begin_expr() {
2397 let e = self.parse_expr()?;
2399 ex = ExprKind::Ret(Some(e));
2401 ex = ExprKind::Ret(None);
2403 } else if self.eat_keyword(keywords::Break) {
2404 let label = self.eat_label();
2405 let e = if self.token.can_begin_expr()
2406 && !(self.token == token::OpenDelim(token::Brace)
2407 && self.restrictions.contains(
2408 Restrictions::NO_STRUCT_LITERAL)) {
2409 Some(self.parse_expr()?)
2413 ex = ExprKind::Break(label, e);
2414 hi = self.prev_span;
2415 } else if self.eat_keyword(keywords::Yield) {
2416 if self.token.can_begin_expr() {
2417 let e = self.parse_expr()?;
2419 ex = ExprKind::Yield(Some(e));
2421 ex = ExprKind::Yield(None);
2423 } else if self.token.is_keyword(keywords::Let) {
2424 // Catch this syntax error here, instead of in `parse_ident`, so
2425 // that we can explicitly mention that let is not to be used as an expression
2426 let mut db = self.fatal("expected expression, found statement (`let`)");
2427 db.span_label(self.span, "expected expression");
2428 db.note("variable declaration using `let` is a statement");
2430 } else if self.token.is_path_start() {
2431 let pth = self.parse_path(PathStyle::Expr)?;
2433 // `!`, as an operator, is prefix, so we know this isn't that
2434 if self.eat(&token::Not) {
2435 // MACRO INVOCATION expression
2436 let (delim, tts) = self.expect_delimited_token_tree()?;
2437 let hi = self.prev_span;
2438 let node = Mac_ { path: pth, tts, delim };
2439 return Ok(self.mk_mac_expr(lo.to(hi), node, attrs))
2441 if self.check(&token::OpenDelim(token::Brace)) {
2442 // This is a struct literal, unless we're prohibited
2443 // from parsing struct literals here.
2444 let prohibited = self.restrictions.contains(
2445 Restrictions::NO_STRUCT_LITERAL
2448 return self.parse_struct_expr(lo, pth, attrs);
2453 ex = ExprKind::Path(None, pth);
2455 match self.parse_literal_maybe_minus() {
2458 ex = expr.node.clone();
2461 self.cancel(&mut err);
2462 let msg = format!("expected expression, found {}",
2463 self.this_token_descr());
2464 let mut err = self.fatal(&msg);
2465 err.span_label(self.span, "expected expression");
2473 let expr = Expr { node: ex, span: lo.to(hi), id: ast::DUMMY_NODE_ID, attrs };
2474 let expr = self.maybe_recover_from_bad_qpath(expr, true)?;
2479 fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Attribute>)
2480 -> PResult<'a, P<Expr>> {
2481 let struct_sp = lo.to(self.prev_span);
2483 let mut fields = Vec::new();
2484 let mut base = None;
2486 attrs.extend(self.parse_inner_attributes()?);
2488 while self.token != token::CloseDelim(token::Brace) {
2489 if self.eat(&token::DotDot) {
2490 let exp_span = self.prev_span;
2491 match self.parse_expr() {
2497 self.recover_stmt();
2500 if self.token == token::Comma {
2501 let mut err = self.sess.span_diagnostic.mut_span_err(
2502 exp_span.to(self.prev_span),
2503 "cannot use a comma after the base struct",
2505 err.span_suggestion_short_with_applicability(
2507 "remove this comma",
2509 Applicability::MachineApplicable
2511 err.note("the base struct must always be the last field");
2513 self.recover_stmt();
2518 match self.parse_field() {
2519 Ok(f) => fields.push(f),
2521 e.span_label(struct_sp, "while parsing this struct");
2524 // If the next token is a comma, then try to parse
2525 // what comes next as additional fields, rather than
2526 // bailing out until next `}`.
2527 if self.token != token::Comma {
2528 self.recover_stmt();
2534 match self.expect_one_of(&[token::Comma],
2535 &[token::CloseDelim(token::Brace)]) {
2539 self.recover_stmt();
2545 let span = lo.to(self.span);
2546 self.expect(&token::CloseDelim(token::Brace))?;
2547 return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
2550 fn parse_or_use_outer_attributes(&mut self,
2551 already_parsed_attrs: Option<ThinVec<Attribute>>)
2552 -> PResult<'a, ThinVec<Attribute>> {
2553 if let Some(attrs) = already_parsed_attrs {
2556 self.parse_outer_attributes().map(|a| a.into())
2560 /// Parse a block or unsafe block
2561 fn parse_block_expr(&mut self, opt_label: Option<Label>,
2562 lo: Span, blk_mode: BlockCheckMode,
2563 outer_attrs: ThinVec<Attribute>)
2564 -> PResult<'a, P<Expr>> {
2565 self.expect(&token::OpenDelim(token::Brace))?;
2567 let mut attrs = outer_attrs;
2568 attrs.extend(self.parse_inner_attributes()?);
2570 let blk = self.parse_block_tail(lo, blk_mode)?;
2571 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs));
2574 /// parse a.b or a(13) or a[4] or just a
2575 fn parse_dot_or_call_expr(&mut self,
2576 already_parsed_attrs: Option<ThinVec<Attribute>>)
2577 -> PResult<'a, P<Expr>> {
2578 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2580 let b = self.parse_bottom_expr();
2581 let (span, b) = self.interpolated_or_expr_span(b)?;
2582 self.parse_dot_or_call_expr_with(b, span, attrs)
2585 fn parse_dot_or_call_expr_with(&mut self,
2588 mut attrs: ThinVec<Attribute>)
2589 -> PResult<'a, P<Expr>> {
2590 // Stitch the list of outer attributes onto the return value.
2591 // A little bit ugly, but the best way given the current code
2593 self.parse_dot_or_call_expr_with_(e0, lo)
2595 expr.map(|mut expr| {
2596 attrs.extend::<Vec<_>>(expr.attrs.into());
2599 ExprKind::If(..) | ExprKind::IfLet(..) => {
2600 if !expr.attrs.is_empty() {
2601 // Just point to the first attribute in there...
2602 let span = expr.attrs[0].span;
2605 "attributes are not yet allowed on `if` \
2616 // Assuming we have just parsed `.`, continue parsing into an expression.
2617 fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2618 let segment = self.parse_path_segment(PathStyle::Expr, true)?;
2619 Ok(match self.token {
2620 token::OpenDelim(token::Paren) => {
2621 // Method call `expr.f()`
2622 let mut args = self.parse_unspanned_seq(
2623 &token::OpenDelim(token::Paren),
2624 &token::CloseDelim(token::Paren),
2625 SeqSep::trailing_allowed(token::Comma),
2626 |p| Ok(p.parse_expr()?)
2628 args.insert(0, self_arg);
2630 let span = lo.to(self.prev_span);
2631 self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
2634 // Field access `expr.f`
2635 if let Some(args) = segment.args {
2636 self.span_err(args.span(),
2637 "field expressions may not have generic arguments");
2640 let span = lo.to(self.prev_span);
2641 self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
2646 fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2651 while self.eat(&token::Question) {
2652 let hi = self.prev_span;
2653 e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
2657 if self.eat(&token::Dot) {
2659 token::Ident(..) => {
2660 e = self.parse_dot_suffix(e, lo)?;
2662 token::Literal(token::Integer(name), _) => {
2663 let span = self.span;
2665 let field = ExprKind::Field(e, Ident::new(name, span));
2666 e = self.mk_expr(lo.to(span), field, ThinVec::new());
2668 token::Literal(token::Float(n), _suf) => {
2670 let fstr = n.as_str();
2671 let mut err = self.diagnostic().struct_span_err(self.prev_span,
2672 &format!("unexpected token: `{}`", n));
2673 err.span_label(self.prev_span, "unexpected token");
2674 if fstr.chars().all(|x| "0123456789.".contains(x)) {
2675 let float = match fstr.parse::<f64>().ok() {
2679 let sugg = pprust::to_string(|s| {
2680 use print::pprust::PrintState;
2684 s.print_usize(float.trunc() as usize)?;
2687 s.s.word(fstr.splitn(2, ".").last().unwrap())
2689 err.span_suggestion_with_applicability(
2690 lo.to(self.prev_span),
2691 "try parenthesizing the first index",
2693 Applicability::MachineApplicable
2700 // FIXME Could factor this out into non_fatal_unexpected or something.
2701 let actual = self.this_token_to_string();
2702 self.span_err(self.span, &format!("unexpected token: `{}`", actual));
2707 if self.expr_is_complete(&e) { break; }
2710 token::OpenDelim(token::Paren) => {
2711 let es = self.parse_unspanned_seq(
2712 &token::OpenDelim(token::Paren),
2713 &token::CloseDelim(token::Paren),
2714 SeqSep::trailing_allowed(token::Comma),
2715 |p| Ok(p.parse_expr()?)
2717 hi = self.prev_span;
2719 let nd = self.mk_call(e, es);
2720 e = self.mk_expr(lo.to(hi), nd, ThinVec::new());
2724 // Could be either an index expression or a slicing expression.
2725 token::OpenDelim(token::Bracket) => {
2727 let ix = self.parse_expr()?;
2729 self.expect(&token::CloseDelim(token::Bracket))?;
2730 let index = self.mk_index(e, ix);
2731 e = self.mk_expr(lo.to(hi), index, ThinVec::new())
2739 crate fn process_potential_macro_variable(&mut self) {
2740 let (token, span) = match self.token {
2741 token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
2742 self.look_ahead(1, |t| t.is_ident()) => {
2744 let name = match self.token {
2745 token::Ident(ident, _) => ident,
2748 let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
2749 err.span_label(self.span, "unknown macro variable");
2753 token::Interpolated(ref nt) => {
2754 self.meta_var_span = Some(self.span);
2755 // Interpolated identifier and lifetime tokens are replaced with usual identifier
2756 // and lifetime tokens, so the former are never encountered during normal parsing.
2758 token::NtIdent(ident, is_raw) => (token::Ident(ident, is_raw), ident.span),
2759 token::NtLifetime(ident) => (token::Lifetime(ident), ident.span),
2769 /// parse a single token tree from the input.
2770 crate fn parse_token_tree(&mut self) -> TokenTree {
2772 token::OpenDelim(..) => {
2773 let frame = mem::replace(&mut self.token_cursor.frame,
2774 self.token_cursor.stack.pop().unwrap());
2775 self.span = frame.span;
2777 TokenTree::Delimited(frame.span, Delimited {
2779 tts: frame.tree_cursor.original_stream().into(),
2782 token::CloseDelim(_) | token::Eof => unreachable!(),
2784 let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span);
2786 TokenTree::Token(span, token)
2791 // parse a stream of tokens into a list of TokenTree's,
2793 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
2794 let mut tts = Vec::new();
2795 while self.token != token::Eof {
2796 tts.push(self.parse_token_tree());
2801 pub fn parse_tokens(&mut self) -> TokenStream {
2802 let mut result = Vec::new();
2805 token::Eof | token::CloseDelim(..) => break,
2806 _ => result.push(self.parse_token_tree().into()),
2809 TokenStream::concat(result)
2812 /// Parse a prefix-unary-operator expr
2813 fn parse_prefix_expr(&mut self,
2814 already_parsed_attrs: Option<ThinVec<Attribute>>)
2815 -> PResult<'a, P<Expr>> {
2816 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2818 // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2819 let (hi, ex) = match self.token {
2822 let e = self.parse_prefix_expr(None);
2823 let (span, e) = self.interpolated_or_expr_span(e)?;
2824 (lo.to(span), self.mk_unary(UnOp::Not, e))
2826 // Suggest `!` for bitwise negation when encountering a `~`
2829 let e = self.parse_prefix_expr(None);
2830 let (span, e) = self.interpolated_or_expr_span(e)?;
2831 let span_of_tilde = lo;
2832 let mut err = self.diagnostic().struct_span_err(span_of_tilde,
2833 "`~` cannot be used as a unary operator");
2834 err.span_suggestion_short_with_applicability(
2836 "use `!` to perform bitwise negation",
2838 Applicability::MachineApplicable
2841 (lo.to(span), self.mk_unary(UnOp::Not, e))
2843 token::BinOp(token::Minus) => {
2845 let e = self.parse_prefix_expr(None);
2846 let (span, e) = self.interpolated_or_expr_span(e)?;
2847 (lo.to(span), self.mk_unary(UnOp::Neg, e))
2849 token::BinOp(token::Star) => {
2851 let e = self.parse_prefix_expr(None);
2852 let (span, e) = self.interpolated_or_expr_span(e)?;
2853 (lo.to(span), self.mk_unary(UnOp::Deref, e))
2855 token::BinOp(token::And) | token::AndAnd => {
2857 let m = self.parse_mutability();
2858 let e = self.parse_prefix_expr(None);
2859 let (span, e) = self.interpolated_or_expr_span(e)?;
2860 (lo.to(span), ExprKind::AddrOf(m, e))
2862 token::Ident(..) if self.token.is_keyword(keywords::In) => {
2864 let place = self.parse_expr_res(
2865 Restrictions::NO_STRUCT_LITERAL,
2868 let blk = self.parse_block()?;
2869 let span = blk.span;
2870 let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new());
2871 (lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr))
2873 token::Ident(..) if self.token.is_keyword(keywords::Box) => {
2875 let e = self.parse_prefix_expr(None);
2876 let (span, e) = self.interpolated_or_expr_span(e)?;
2877 (lo.to(span), ExprKind::Box(e))
2879 token::Ident(..) if self.token.is_ident_named("not") => {
2880 // `not` is just an ordinary identifier in Rust-the-language,
2881 // but as `rustc`-the-compiler, we can issue clever diagnostics
2882 // for confused users who really want to say `!`
2883 let token_cannot_continue_expr = |t: &token::Token| match *t {
2884 // These tokens can start an expression after `!`, but
2885 // can't continue an expression after an ident
2886 token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw),
2887 token::Literal(..) | token::Pound => true,
2888 token::Interpolated(ref nt) => match nt.0 {
2889 token::NtIdent(..) | token::NtExpr(..) |
2890 token::NtBlock(..) | token::NtPath(..) => true,
2895 let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
2896 if cannot_continue_expr {
2898 // Emit the error ...
2899 let mut err = self.diagnostic()
2900 .struct_span_err(self.span,
2901 &format!("unexpected {} after identifier",
2902 self.this_token_descr()));
2903 // span the `not` plus trailing whitespace to avoid
2904 // trailing whitespace after the `!` in our suggestion
2905 let to_replace = self.sess.source_map()
2906 .span_until_non_whitespace(lo.to(self.span));
2907 err.span_suggestion_short_with_applicability(
2909 "use `!` to perform logical negation",
2911 Applicability::MachineApplicable
2914 // —and recover! (just as if we were in the block
2915 // for the `token::Not` arm)
2916 let e = self.parse_prefix_expr(None);
2917 let (span, e) = self.interpolated_or_expr_span(e)?;
2918 (lo.to(span), self.mk_unary(UnOp::Not, e))
2920 return self.parse_dot_or_call_expr(Some(attrs));
2923 _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
2925 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2928 /// Parse an associative expression
2930 /// This parses an expression accounting for associativity and precedence of the operators in
2932 fn parse_assoc_expr(&mut self,
2933 already_parsed_attrs: Option<ThinVec<Attribute>>)
2934 -> PResult<'a, P<Expr>> {
2935 self.parse_assoc_expr_with(0, already_parsed_attrs.into())
2938 /// Parse an associative expression with operators of at least `min_prec` precedence
2939 fn parse_assoc_expr_with(&mut self,
2942 -> PResult<'a, P<Expr>> {
2943 let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
2946 let attrs = match lhs {
2947 LhsExpr::AttributesParsed(attrs) => Some(attrs),
2950 if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token) {
2951 return self.parse_prefix_range_expr(attrs);
2953 self.parse_prefix_expr(attrs)?
2957 if self.expr_is_complete(&lhs) {
2958 // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
2961 self.expected_tokens.push(TokenType::Operator);
2962 while let Some(op) = AssocOp::from_token(&self.token) {
2964 // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
2965 // it refers to. Interpolated identifiers are unwrapped early and never show up here
2966 // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
2967 // it as "interpolated", it doesn't change the answer for non-interpolated idents.
2968 let lhs_span = match (self.prev_token_kind, &lhs.node) {
2969 (PrevTokenKind::Interpolated, _) => self.prev_span,
2970 (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
2971 if path.segments.len() == 1 => self.prev_span,
2975 let cur_op_span = self.span;
2976 let restrictions = if op.is_assign_like() {
2977 self.restrictions & Restrictions::NO_STRUCT_LITERAL
2981 if op.precedence() < min_prec {
2984 // Check for deprecated `...` syntax
2985 if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
2986 self.err_dotdotdot_syntax(self.span);
2990 if op.is_comparison() {
2991 self.check_no_chained_comparison(&lhs, &op);
2994 if op == AssocOp::As {
2995 lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
2997 } else if op == AssocOp::Colon {
2998 lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) {
3001 err.span_label(self.span,
3002 "expecting a type here because of type ascription");
3003 let cm = self.sess.source_map();
3004 let cur_pos = cm.lookup_char_pos(self.span.lo());
3005 let op_pos = cm.lookup_char_pos(cur_op_span.hi());
3006 if cur_pos.line != op_pos.line {
3007 err.span_suggestion_with_applicability(
3009 "try using a semicolon",
3011 Applicability::MaybeIncorrect // speculative
3018 } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
3019 // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
3020 // generalise it to the Fixity::None code.
3022 // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
3023 // two variants are handled with `parse_prefix_range_expr` call above.
3024 let rhs = if self.is_at_start_of_range_notation_rhs() {
3025 Some(self.parse_assoc_expr_with(op.precedence() + 1,
3026 LhsExpr::NotYetParsed)?)
3030 let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
3035 let limits = if op == AssocOp::DotDot {
3036 RangeLimits::HalfOpen
3041 let r = try!(self.mk_range(Some(lhs), rhs, limits));
3042 lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
3046 let rhs = match op.fixity() {
3047 Fixity::Right => self.with_res(
3048 restrictions - Restrictions::STMT_EXPR,
3050 this.parse_assoc_expr_with(op.precedence(),
3051 LhsExpr::NotYetParsed)
3053 Fixity::Left => self.with_res(
3054 restrictions - Restrictions::STMT_EXPR,
3056 this.parse_assoc_expr_with(op.precedence() + 1,
3057 LhsExpr::NotYetParsed)
3059 // We currently have no non-associative operators that are not handled above by
3060 // the special cases. The code is here only for future convenience.
3061 Fixity::None => self.with_res(
3062 restrictions - Restrictions::STMT_EXPR,
3064 this.parse_assoc_expr_with(op.precedence() + 1,
3065 LhsExpr::NotYetParsed)
3069 let span = lhs_span.to(rhs.span);
3071 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
3072 AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
3073 AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
3074 AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
3075 AssocOp::Greater | AssocOp::GreaterEqual => {
3076 let ast_op = op.to_ast_binop().unwrap();
3077 let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
3078 self.mk_expr(span, binary, ThinVec::new())
3081 self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
3082 AssocOp::ObsoleteInPlace =>
3083 self.mk_expr(span, ExprKind::ObsoleteInPlace(lhs, rhs), ThinVec::new()),
3084 AssocOp::AssignOp(k) => {
3086 token::Plus => BinOpKind::Add,
3087 token::Minus => BinOpKind::Sub,
3088 token::Star => BinOpKind::Mul,
3089 token::Slash => BinOpKind::Div,
3090 token::Percent => BinOpKind::Rem,
3091 token::Caret => BinOpKind::BitXor,
3092 token::And => BinOpKind::BitAnd,
3093 token::Or => BinOpKind::BitOr,
3094 token::Shl => BinOpKind::Shl,
3095 token::Shr => BinOpKind::Shr,
3097 let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
3098 self.mk_expr(span, aopexpr, ThinVec::new())
3100 AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
3101 self.bug("AssocOp should have been handled by special case")
3105 if op.fixity() == Fixity::None { break }
3110 fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
3111 expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
3112 -> PResult<'a, P<Expr>> {
3113 let mk_expr = |this: &mut Self, rhs: P<Ty>| {
3114 this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
3117 // Save the state of the parser before parsing type normally, in case there is a
3118 // LessThan comparison after this cast.
3119 let parser_snapshot_before_type = self.clone();
3120 match self.parse_ty_no_plus() {
3122 Ok(mk_expr(self, rhs))
3124 Err(mut type_err) => {
3125 // Rewind to before attempting to parse the type with generics, to recover
3126 // from situations like `x as usize < y` in which we first tried to parse
3127 // `usize < y` as a type with generic arguments.
3128 let parser_snapshot_after_type = self.clone();
3129 mem::replace(self, parser_snapshot_before_type);
3131 match self.parse_path(PathStyle::Expr) {
3133 let (op_noun, op_verb) = match self.token {
3134 token::Lt => ("comparison", "comparing"),
3135 token::BinOp(token::Shl) => ("shift", "shifting"),
3137 // We can end up here even without `<` being the next token, for
3138 // example because `parse_ty_no_plus` returns `Err` on keywords,
3139 // but `parse_path` returns `Ok` on them due to error recovery.
3140 // Return original error and parser state.
3141 mem::replace(self, parser_snapshot_after_type);
3142 return Err(type_err);
3146 // Successfully parsed the type path leaving a `<` yet to parse.
3149 // Report non-fatal diagnostics, keep `x as usize` as an expression
3150 // in AST and continue parsing.
3151 let msg = format!("`<` is interpreted as a start of generic \
3152 arguments for `{}`, not a {}", path, op_noun);
3153 let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
3154 err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span),
3155 "interpreted as generic arguments");
3156 err.span_label(self.span, format!("not interpreted as {}", op_noun));
3158 let expr = mk_expr(self, P(Ty {
3160 node: TyKind::Path(None, path),
3161 id: ast::DUMMY_NODE_ID
3164 let expr_str = self.sess.source_map().span_to_snippet(expr.span)
3165 .unwrap_or(pprust::expr_to_string(&expr));
3166 err.span_suggestion_with_applicability(
3168 &format!("try {} the cast value", op_verb),
3169 format!("({})", expr_str),
3170 Applicability::MachineApplicable
3176 Err(mut path_err) => {
3177 // Couldn't parse as a path, return original error and parser state.
3179 mem::replace(self, parser_snapshot_after_type);
3187 /// Produce an error if comparison operators are chained (RFC #558).
3188 /// We only need to check lhs, not rhs, because all comparison ops
3189 /// have same precedence and are left-associative
3190 fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
3191 debug_assert!(outer_op.is_comparison(),
3192 "check_no_chained_comparison: {:?} is not comparison",
3195 ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
3196 // respan to include both operators
3197 let op_span = op.span.to(self.span);
3198 let mut err = self.diagnostic().struct_span_err(op_span,
3199 "chained comparison operators require parentheses");
3200 if op.node == BinOpKind::Lt &&
3201 *outer_op == AssocOp::Less || // Include `<` to provide this recommendation
3202 *outer_op == AssocOp::Greater // even in a case like the following:
3203 { // Foo<Bar<Baz<Qux, ()>>>
3205 "use `::<...>` instead of `<...>` if you meant to specify type arguments");
3206 err.help("or use `(...)` if you meant to specify fn arguments");
3214 /// Parse prefix-forms of range notation: `..expr`, `..`, `..=expr`
3215 fn parse_prefix_range_expr(&mut self,
3216 already_parsed_attrs: Option<ThinVec<Attribute>>)
3217 -> PResult<'a, P<Expr>> {
3218 // Check for deprecated `...` syntax
3219 if self.token == token::DotDotDot {
3220 self.err_dotdotdot_syntax(self.span);
3223 debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token),
3224 "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
3226 let tok = self.token.clone();
3227 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
3229 let mut hi = self.span;
3231 let opt_end = if self.is_at_start_of_range_notation_rhs() {
3232 // RHS must be parsed with more associativity than the dots.
3233 let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
3234 Some(self.parse_assoc_expr_with(next_prec,
3235 LhsExpr::NotYetParsed)
3243 let limits = if tok == token::DotDot {
3244 RangeLimits::HalfOpen
3249 let r = try!(self.mk_range(None,
3252 Ok(self.mk_expr(lo.to(hi), r, attrs))
3255 fn is_at_start_of_range_notation_rhs(&self) -> bool {
3256 if self.token.can_begin_expr() {
3257 // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
3258 if self.token == token::OpenDelim(token::Brace) {
3259 return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
3267 /// Parse an 'if' or 'if let' expression ('if' token already eaten)
3268 fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3269 if self.check_keyword(keywords::Let) {
3270 return self.parse_if_let_expr(attrs);
3272 let lo = self.prev_span;
3273 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3275 // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
3276 // verify that the last statement is either an implicit return (no `;`) or an explicit
3277 // return. This won't catch blocks with an explicit `return`, but that would be caught by
3278 // the dead code lint.
3279 if self.eat_keyword(keywords::Else) || !cond.returns() {
3280 let sp = self.sess.source_map().next_point(lo);
3281 let mut err = self.diagnostic()
3282 .struct_span_err(sp, "missing condition for `if` statemement");
3283 err.span_label(sp, "expected if condition here");
3286 let not_block = self.token != token::OpenDelim(token::Brace);
3287 let thn = self.parse_block().map_err(|mut err| {
3289 err.span_label(lo, "this `if` statement has a condition, but no block");
3293 let mut els: Option<P<Expr>> = None;
3294 let mut hi = thn.span;
3295 if self.eat_keyword(keywords::Else) {
3296 let elexpr = self.parse_else_expr()?;
3300 Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
3303 /// Parse an 'if let' expression ('if' token already eaten)
3304 fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
3305 -> PResult<'a, P<Expr>> {
3306 let lo = self.prev_span;
3307 self.expect_keyword(keywords::Let)?;
3308 let pats = self.parse_pats()?;
3309 self.expect(&token::Eq)?;
3310 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3311 let thn = self.parse_block()?;
3312 let (hi, els) = if self.eat_keyword(keywords::Else) {
3313 let expr = self.parse_else_expr()?;
3314 (expr.span, Some(expr))
3318 Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
3321 // `move |args| expr`
3322 fn parse_lambda_expr(&mut self,
3323 attrs: ThinVec<Attribute>)
3324 -> PResult<'a, P<Expr>>
3327 let movability = if self.eat_keyword(keywords::Static) {
3332 let asyncness = if self.span.edition() >= Edition::Edition2018 {
3333 self.parse_asyncness()
3337 let capture_clause = if self.eat_keyword(keywords::Move) {
3342 let decl = self.parse_fn_block_decl()?;
3343 let decl_hi = self.prev_span;
3344 let body = match decl.output {
3345 FunctionRetTy::Default(_) => {
3346 let restrictions = self.restrictions - Restrictions::STMT_EXPR;
3347 self.parse_expr_res(restrictions, None)?
3350 // If an explicit return type is given, require a
3351 // block to appear (RFC 968).
3352 let body_lo = self.span;
3353 self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
3359 ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
3363 // `else` token already eaten
3364 fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
3365 if self.eat_keyword(keywords::If) {
3366 return self.parse_if_expr(ThinVec::new());
3368 let blk = self.parse_block()?;
3369 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
3373 /// Parse a 'for' .. 'in' expression ('for' token already eaten)
3374 fn parse_for_expr(&mut self, opt_label: Option<Label>,
3376 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3377 // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
3379 let pat = self.parse_top_level_pat()?;
3380 if !self.eat_keyword(keywords::In) {
3381 let in_span = self.prev_span.between(self.span);
3382 let mut err = self.sess.span_diagnostic
3383 .struct_span_err(in_span, "missing `in` in `for` loop");
3384 err.span_suggestion_short_with_applicability(
3385 in_span, "try adding `in` here", " in ".into(),
3386 // has been misleading, at least in the past (closed Issue #48492)
3387 Applicability::MaybeIncorrect
3391 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3392 let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
3393 attrs.extend(iattrs);
3395 let hi = self.prev_span;
3396 Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
3399 /// Parse a 'while' or 'while let' expression ('while' token already eaten)
3400 fn parse_while_expr(&mut self, opt_label: Option<Label>,
3402 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3403 if self.token.is_keyword(keywords::Let) {
3404 return self.parse_while_let_expr(opt_label, span_lo, attrs);
3406 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3407 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3408 attrs.extend(iattrs);
3409 let span = span_lo.to(body.span);
3410 return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs));
3413 /// Parse a 'while let' expression ('while' token already eaten)
3414 fn parse_while_let_expr(&mut self, opt_label: Option<Label>,
3416 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3417 self.expect_keyword(keywords::Let)?;
3418 let pats = self.parse_pats()?;
3419 self.expect(&token::Eq)?;
3420 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3421 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3422 attrs.extend(iattrs);
3423 let span = span_lo.to(body.span);
3424 return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
3427 // parse `loop {...}`, `loop` token already eaten
3428 fn parse_loop_expr(&mut self, opt_label: Option<Label>,
3430 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3431 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3432 attrs.extend(iattrs);
3433 let span = span_lo.to(body.span);
3434 Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
3437 /// Parse an `async move {...}` expression
3438 pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>)
3439 -> PResult<'a, P<Expr>>
3441 let span_lo = self.span;
3442 self.expect_keyword(keywords::Async)?;
3443 let capture_clause = if self.eat_keyword(keywords::Move) {
3448 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3449 attrs.extend(iattrs);
3451 span_lo.to(body.span),
3452 ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs))
3455 /// Parse a `do catch {...}` expression (`do catch` token already eaten)
3456 fn parse_catch_expr(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
3457 -> PResult<'a, P<Expr>>
3459 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3460 attrs.extend(iattrs);
3461 Ok(self.mk_expr(span_lo.to(body.span), ExprKind::Catch(body), attrs))
3464 // `match` token already eaten
3465 fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3466 let match_span = self.prev_span;
3467 let lo = self.prev_span;
3468 let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL,
3470 if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
3471 if self.token == token::Token::Semi {
3472 e.span_suggestion_short_with_applicability(
3474 "try removing this `match`",
3476 Applicability::MaybeIncorrect // speculative
3481 attrs.extend(self.parse_inner_attributes()?);
3483 let mut arms: Vec<Arm> = Vec::new();
3484 while self.token != token::CloseDelim(token::Brace) {
3485 match self.parse_arm() {
3486 Ok(arm) => arms.push(arm),
3488 // Recover by skipping to the end of the block.
3490 self.recover_stmt();
3491 let span = lo.to(self.span);
3492 if self.token == token::CloseDelim(token::Brace) {
3495 return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
3501 return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
3504 crate fn parse_arm(&mut self) -> PResult<'a, Arm> {
3505 maybe_whole!(self, NtArm, |x| x);
3507 let attrs = self.parse_outer_attributes()?;
3508 // Allow a '|' before the pats (RFC 1925)
3509 self.eat(&token::BinOp(token::Or));
3510 let pats = self.parse_pats()?;
3511 let guard = if self.eat_keyword(keywords::If) {
3512 Some(self.parse_expr()?)
3516 let arrow_span = self.span;
3517 self.expect(&token::FatArrow)?;
3518 let arm_start_span = self.span;
3520 let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
3521 .map_err(|mut err| {
3522 err.span_label(arrow_span, "while parsing the `match` arm starting here");
3526 let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
3527 && self.token != token::CloseDelim(token::Brace);
3530 let cm = self.sess.source_map();
3531 self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
3532 .map_err(|mut err| {
3533 match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
3534 (Ok(ref expr_lines), Ok(ref arm_start_lines))
3535 if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
3536 && expr_lines.lines.len() == 2
3537 && self.token == token::FatArrow => {
3538 // We check whether there's any trailing code in the parse span,
3539 // if there isn't, we very likely have the following:
3542 // | -- - missing comma
3548 // | parsed until here as `"y" & X`
3549 err.span_suggestion_short_with_applicability(
3550 cm.next_point(arm_start_span),
3551 "missing a comma here to end this `match` arm",
3553 Applicability::MachineApplicable
3557 err.span_label(arrow_span,
3558 "while parsing the `match` arm starting here");
3564 self.eat(&token::Comma);
3575 /// Parse an expression
3576 pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
3577 self.parse_expr_res(Restrictions::empty(), None)
3580 /// Evaluate the closure with restrictions in place.
3582 /// After the closure is evaluated, restrictions are reset.
3583 fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T
3584 where F: FnOnce(&mut Self) -> T
3586 let old = self.restrictions;
3587 self.restrictions = r;
3589 self.restrictions = old;
3594 /// Parse an expression, subject to the given restrictions
3595 fn parse_expr_res(&mut self, r: Restrictions,
3596 already_parsed_attrs: Option<ThinVec<Attribute>>)
3597 -> PResult<'a, P<Expr>> {
3598 self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
3601 /// Parse the RHS of a local variable declaration (e.g. '= 14;')
3602 fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
3603 if self.check(&token::Eq) {
3605 Ok(Some(self.parse_expr()?))
3607 Ok(Some(self.parse_expr()?))
3613 /// Parse patterns, separated by '|' s
3614 fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3615 let mut pats = Vec::new();
3617 pats.push(self.parse_top_level_pat()?);
3619 if self.token == token::OrOr {
3620 let mut err = self.struct_span_err(self.span,
3621 "unexpected token `||` after pattern");
3622 err.span_suggestion_with_applicability(
3624 "use a single `|` to specify multiple patterns",
3626 Applicability::MachineApplicable
3630 } else if self.check(&token::BinOp(token::Or)) {
3638 // Parses a parenthesized list of patterns like
3639 // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns:
3640 // - a vector of the patterns that were parsed
3641 // - an option indicating the index of the `..` element
3642 // - a boolean indicating whether a trailing comma was present.
3643 // Trailing commas are significant because (p) and (p,) are different patterns.
3644 fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3645 self.expect(&token::OpenDelim(token::Paren))?;
3646 let result = self.parse_pat_list()?;
3647 self.expect(&token::CloseDelim(token::Paren))?;
3651 fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3652 let mut fields = Vec::new();
3653 let mut ddpos = None;
3654 let mut trailing_comma = false;
3656 if self.eat(&token::DotDot) {
3657 if ddpos.is_none() {
3658 ddpos = Some(fields.len());
3660 // Emit a friendly error, ignore `..` and continue parsing
3661 self.span_err(self.prev_span,
3662 "`..` can only be used once per tuple or tuple struct pattern");
3664 } else if !self.check(&token::CloseDelim(token::Paren)) {
3665 fields.push(self.parse_pat()?);
3670 trailing_comma = self.eat(&token::Comma);
3671 if !trailing_comma {
3676 if ddpos == Some(fields.len()) && trailing_comma {
3677 // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
3678 self.span_err(self.prev_span, "trailing comma is not permitted after `..`");
3681 Ok((fields, ddpos, trailing_comma))
3684 fn parse_pat_vec_elements(
3686 ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3687 let mut before = Vec::new();
3688 let mut slice = None;
3689 let mut after = Vec::new();
3690 let mut first = true;
3691 let mut before_slice = true;
3693 while self.token != token::CloseDelim(token::Bracket) {
3697 self.expect(&token::Comma)?;
3699 if self.token == token::CloseDelim(token::Bracket)
3700 && (before_slice || !after.is_empty()) {
3706 if self.eat(&token::DotDot) {
3708 if self.check(&token::Comma) ||
3709 self.check(&token::CloseDelim(token::Bracket)) {
3710 slice = Some(P(Pat {
3711 id: ast::DUMMY_NODE_ID,
3712 node: PatKind::Wild,
3713 span: self.prev_span,
3715 before_slice = false;
3721 let subpat = self.parse_pat()?;
3722 if before_slice && self.eat(&token::DotDot) {
3723 slice = Some(subpat);
3724 before_slice = false;
3725 } else if before_slice {
3726 before.push(subpat);
3732 Ok((before, slice, after))
3738 attrs: Vec<Attribute>
3739 ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> {
3740 // Check if a colon exists one ahead. This means we're parsing a fieldname.
3742 let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3743 // Parsing a pattern of the form "fieldname: pat"
3744 let fieldname = self.parse_field_name()?;
3746 let pat = self.parse_pat()?;
3748 (pat, fieldname, false)
3750 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3751 let is_box = self.eat_keyword(keywords::Box);
3752 let boxed_span = self.span;
3753 let is_ref = self.eat_keyword(keywords::Ref);
3754 let is_mut = self.eat_keyword(keywords::Mut);
3755 let fieldname = self.parse_ident()?;
3756 hi = self.prev_span;
3758 let bind_type = match (is_ref, is_mut) {
3759 (true, true) => BindingMode::ByRef(Mutability::Mutable),
3760 (true, false) => BindingMode::ByRef(Mutability::Immutable),
3761 (false, true) => BindingMode::ByValue(Mutability::Mutable),
3762 (false, false) => BindingMode::ByValue(Mutability::Immutable),
3764 let fieldpat = P(Pat {
3765 id: ast::DUMMY_NODE_ID,
3766 node: PatKind::Ident(bind_type, fieldname, None),
3767 span: boxed_span.to(hi),
3770 let subpat = if is_box {
3772 id: ast::DUMMY_NODE_ID,
3773 node: PatKind::Box(fieldpat),
3779 (subpat, fieldname, true)
3782 Ok(source_map::Spanned {
3784 node: ast::FieldPat {
3788 attrs: attrs.into(),
3793 /// Parse the fields of a struct-like pattern
3794 fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> {
3795 let mut fields = Vec::new();
3796 let mut etc = false;
3797 let mut ate_comma = true;
3798 let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
3799 let mut etc_span = None;
3801 while self.token != token::CloseDelim(token::Brace) {
3802 let attrs = self.parse_outer_attributes()?;
3805 // check that a comma comes after every field
3807 let err = self.struct_span_err(self.prev_span, "expected `,`");
3812 if self.check(&token::DotDot) || self.token == token::DotDotDot {
3814 let mut etc_sp = self.span;
3816 if self.token == token::DotDotDot { // Issue #46718
3817 // Accept `...` as if it were `..` to avoid further errors
3818 let mut err = self.struct_span_err(self.span,
3819 "expected field pattern, found `...`");
3820 err.span_suggestion_with_applicability(
3822 "to omit remaining fields, use one fewer `.`",
3824 Applicability::MachineApplicable
3828 self.bump(); // `..` || `...`:w
3830 if self.token == token::CloseDelim(token::Brace) {
3831 etc_span = Some(etc_sp);
3834 let token_str = self.this_token_to_string();
3835 let mut err = self.fatal(&format!("expected `}}`, found `{}`", token_str));
3837 err.span_label(self.span, "expected `}`");
3838 let mut comma_sp = None;
3839 if self.token == token::Comma { // Issue #49257
3840 etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span));
3841 err.span_label(etc_sp,
3842 "`..` must be at the end and cannot have a trailing comma");
3843 comma_sp = Some(self.span);
3848 etc_span = Some(etc_sp);
3849 if self.token == token::CloseDelim(token::Brace) {
3850 // If the struct looks otherwise well formed, recover and continue.
3851 if let Some(sp) = comma_sp {
3852 err.span_suggestion_short(sp, "remove this comma", "".into());
3856 } else if self.token.is_ident() && ate_comma {
3857 // Accept fields coming after `..,`.
3858 // This way we avoid "pattern missing fields" errors afterwards.
3859 // We delay this error until the end in order to have a span for a
3861 if let Some(mut delayed_err) = delayed_err {
3865 delayed_err = Some(err);
3868 if let Some(mut err) = delayed_err {
3875 fields.push(match self.parse_pat_field(lo, attrs) {
3878 if let Some(mut delayed_err) = delayed_err {
3884 ate_comma = self.eat(&token::Comma);
3887 if let Some(mut err) = delayed_err {
3888 if let Some(etc_span) = etc_span {
3889 err.multipart_suggestion(
3890 "move the `..` to the end of the field list",
3892 (etc_span, "".into()),
3893 (self.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
3899 return Ok((fields, etc));
3902 fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
3903 if self.token.is_path_start() {
3905 let (qself, path) = if self.eat_lt() {
3906 // Parse a qualified path
3907 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
3910 // Parse an unqualified path
3911 (None, self.parse_path(PathStyle::Expr)?)
3913 let hi = self.prev_span;
3914 Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
3916 self.parse_literal_maybe_minus()
3920 // helper function to decide whether to parse as ident binding or to try to do
3921 // something more complex like range patterns
3922 fn parse_as_ident(&mut self) -> bool {
3923 self.look_ahead(1, |t| match *t {
3924 token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
3925 token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false),
3926 // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the
3927 // range pattern branch
3928 token::DotDot => None,
3930 }).unwrap_or_else(|| self.look_ahead(2, |t| match *t {
3931 token::Comma | token::CloseDelim(token::Bracket) => true,
3936 /// A wrapper around `parse_pat` with some special error handling for the
3937 /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
3938 /// to subpatterns within such).
3939 fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
3940 let pat = self.parse_pat()?;
3941 if self.token == token::Comma {
3942 // An unexpected comma after a top-level pattern is a clue that the
3943 // user (perhaps more accustomed to some other language) forgot the
3944 // parentheses in what should have been a tuple pattern; return a
3945 // suggestion-enhanced error here rather than choking on the comma
3947 let comma_span = self.span;
3949 if let Err(mut err) = self.parse_pat_list() {
3950 // We didn't expect this to work anyway; we just wanted
3951 // to advance to the end of the comma-sequence so we know
3952 // the span to suggest parenthesizing
3955 let seq_span = pat.span.to(self.prev_span);
3956 let mut err = self.struct_span_err(comma_span,
3957 "unexpected `,` in pattern");
3958 if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) {
3959 err.span_suggestion_with_applicability(
3961 "try adding parentheses",
3962 format!("({})", seq_snippet),
3963 Applicability::MachineApplicable
3971 /// Parse a pattern.
3972 pub fn parse_pat(&mut self) -> PResult<'a, P<Pat>> {
3973 self.parse_pat_with_range_pat(true)
3976 /// Parse a pattern, with a setting whether modern range patterns e.g. `a..=b`, `a..b` are
3978 fn parse_pat_with_range_pat(&mut self, allow_range_pat: bool) -> PResult<'a, P<Pat>> {
3979 maybe_whole!(self, NtPat, |x| x);
3984 token::BinOp(token::And) | token::AndAnd => {
3985 // Parse &pat / &mut pat
3987 let mutbl = self.parse_mutability();
3988 if let token::Lifetime(ident) = self.token {
3989 let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern",
3991 err.span_label(self.span, "unexpected lifetime");
3994 let subpat = self.parse_pat_with_range_pat(false)?;
3995 pat = PatKind::Ref(subpat, mutbl);
3997 token::OpenDelim(token::Paren) => {
3998 // Parse (pat,pat,pat,...) as tuple pattern
3999 let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?;
4000 pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma {
4001 PatKind::Paren(fields.into_iter().nth(0).unwrap())
4003 PatKind::Tuple(fields, ddpos)
4006 token::OpenDelim(token::Bracket) => {
4007 // Parse [pat,pat,...] as slice pattern
4009 let (before, slice, after) = self.parse_pat_vec_elements()?;
4010 self.expect(&token::CloseDelim(token::Bracket))?;
4011 pat = PatKind::Slice(before, slice, after);
4013 // At this point, token != &, &&, (, [
4014 _ => if self.eat_keyword(keywords::Underscore) {
4016 pat = PatKind::Wild;
4017 } else if self.eat_keyword(keywords::Mut) {
4018 // Parse mut ident @ pat / mut ref ident @ pat
4019 let mutref_span = self.prev_span.to(self.span);
4020 let binding_mode = if self.eat_keyword(keywords::Ref) {
4022 .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
4023 .span_suggestion_with_applicability(
4025 "try switching the order",
4027 Applicability::MachineApplicable
4029 BindingMode::ByRef(Mutability::Mutable)
4031 BindingMode::ByValue(Mutability::Mutable)
4033 pat = self.parse_pat_ident(binding_mode)?;
4034 } else if self.eat_keyword(keywords::Ref) {
4035 // Parse ref ident @ pat / ref mut ident @ pat
4036 let mutbl = self.parse_mutability();
4037 pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
4038 } else if self.eat_keyword(keywords::Box) {
4040 let subpat = self.parse_pat_with_range_pat(false)?;
4041 pat = PatKind::Box(subpat);
4042 } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
4043 self.parse_as_ident() {
4044 // Parse ident @ pat
4045 // This can give false positives and parse nullary enums,
4046 // they are dealt with later in resolve
4047 let binding_mode = BindingMode::ByValue(Mutability::Immutable);
4048 pat = self.parse_pat_ident(binding_mode)?;
4049 } else if self.token.is_path_start() {
4050 // Parse pattern starting with a path
4051 let (qself, path) = if self.eat_lt() {
4052 // Parse a qualified path
4053 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
4056 // Parse an unqualified path
4057 (None, self.parse_path(PathStyle::Expr)?)
4060 token::Not if qself.is_none() => {
4061 // Parse macro invocation
4063 let (delim, tts) = self.expect_delimited_token_tree()?;
4064 let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim });
4065 pat = PatKind::Mac(mac);
4067 token::DotDotDot | token::DotDotEq | token::DotDot => {
4068 let end_kind = match self.token {
4069 token::DotDot => RangeEnd::Excluded,
4070 token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot),
4071 token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq),
4072 _ => panic!("can only parse `..`/`...`/`..=` for ranges \
4075 let op_span = self.span;
4077 let span = lo.to(self.prev_span);
4078 let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
4080 let end = self.parse_pat_range_end()?;
4081 let op = Spanned { span: op_span, node: end_kind };
4082 pat = PatKind::Range(begin, end, op);
4084 token::OpenDelim(token::Brace) => {
4085 if qself.is_some() {
4086 let msg = "unexpected `{` after qualified path";
4087 let mut err = self.fatal(msg);
4088 err.span_label(self.span, msg);
4091 // Parse struct pattern
4093 let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
4095 self.recover_stmt();
4099 pat = PatKind::Struct(path, fields, etc);
4101 token::OpenDelim(token::Paren) => {
4102 if qself.is_some() {
4103 let msg = "unexpected `(` after qualified path";
4104 let mut err = self.fatal(msg);
4105 err.span_label(self.span, msg);
4108 // Parse tuple struct or enum pattern
4109 let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?;
4110 pat = PatKind::TupleStruct(path, fields, ddpos)
4112 _ => pat = PatKind::Path(qself, path),
4115 // Try to parse everything else as literal with optional minus
4116 match self.parse_literal_maybe_minus() {
4118 let op_span = self.span;
4119 if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
4120 self.check(&token::DotDotDot) {
4121 let end_kind = if self.eat(&token::DotDotDot) {
4122 RangeEnd::Included(RangeSyntax::DotDotDot)
4123 } else if self.eat(&token::DotDotEq) {
4124 RangeEnd::Included(RangeSyntax::DotDotEq)
4125 } else if self.eat(&token::DotDot) {
4128 panic!("impossible case: we already matched \
4129 on a range-operator token")
4131 let end = self.parse_pat_range_end()?;
4132 let op = Spanned { span: op_span, node: end_kind };
4133 pat = PatKind::Range(begin, end, op);
4135 pat = PatKind::Lit(begin);
4139 self.cancel(&mut err);
4140 let msg = format!("expected pattern, found {}", self.this_token_descr());
4141 let mut err = self.fatal(&msg);
4142 err.span_label(self.span, "expected pattern");
4149 let pat = Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID };
4150 let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
4152 if !allow_range_pat {
4155 _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
4157 PatKind::Range(..) => {
4158 let mut err = self.struct_span_err(
4160 "the range pattern here has ambiguous interpretation",
4162 err.span_suggestion_with_applicability(
4164 "add parentheses to clarify the precedence",
4165 format!("({})", pprust::pat_to_string(&pat)),
4166 // "ambiguous interpretation" implies that we have to be guessing
4167 Applicability::MaybeIncorrect
4178 /// Parse ident or ident @ pat
4179 /// used by the copy foo and ref foo patterns to give a good
4180 /// error message when parsing mistakes like ref foo(a,b)
4181 fn parse_pat_ident(&mut self,
4182 binding_mode: ast::BindingMode)
4183 -> PResult<'a, PatKind> {
4184 let ident = self.parse_ident()?;
4185 let sub = if self.eat(&token::At) {
4186 Some(self.parse_pat()?)
4191 // just to be friendly, if they write something like
4193 // we end up here with ( as the current token. This shortly
4194 // leads to a parse error. Note that if there is no explicit
4195 // binding mode then we do not end up here, because the lookahead
4196 // will direct us over to parse_enum_variant()
4197 if self.token == token::OpenDelim(token::Paren) {
4198 return Err(self.span_fatal(
4200 "expected identifier, found enum pattern"))
4203 Ok(PatKind::Ident(binding_mode, ident, sub))
4206 /// Parse a local variable declaration
4207 fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
4208 let lo = self.prev_span;
4209 let pat = self.parse_top_level_pat()?;
4211 let (err, ty) = if self.eat(&token::Colon) {
4212 // Save the state of the parser before parsing type normally, in case there is a `:`
4213 // instead of an `=` typo.
4214 let parser_snapshot_before_type = self.clone();
4215 let colon_sp = self.prev_span;
4216 match self.parse_ty() {
4217 Ok(ty) => (None, Some(ty)),
4219 // Rewind to before attempting to parse the type and continue parsing
4220 let parser_snapshot_after_type = self.clone();
4221 mem::replace(self, parser_snapshot_before_type);
4223 let snippet = self.sess.source_map().span_to_snippet(pat.span).unwrap();
4224 err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
4225 (Some((parser_snapshot_after_type, colon_sp, err)), None)
4231 let init = match (self.parse_initializer(err.is_some()), err) {
4232 (Ok(init), None) => { // init parsed, ty parsed
4235 (Ok(init), Some((_, colon_sp, mut err))) => { // init parsed, ty error
4236 // Could parse the type as if it were the initializer, it is likely there was a
4237 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
4238 err.span_suggestion_short_with_applicability(
4240 "use `=` if you meant to assign",
4242 Applicability::MachineApplicable
4245 // As this was parsed successfully, continue as if the code has been fixed for the
4246 // rest of the file. It will still fail due to the emitted error, but we avoid
4250 (Err(mut init_err), Some((snapshot, _, ty_err))) => { // init error, ty error
4252 // Couldn't parse the type nor the initializer, only raise the type error and
4253 // return to the parser state before parsing the type as the initializer.
4254 // let x: <parse_error>;
4255 mem::replace(self, snapshot);
4258 (Err(err), None) => { // init error, ty parsed
4259 // Couldn't parse the initializer and we're not attempting to recover a failed
4260 // parse of the type, return the error.
4264 let hi = if self.token == token::Semi {
4273 id: ast::DUMMY_NODE_ID,
4279 /// Parse a structure field
4280 fn parse_name_and_ty(&mut self,
4283 attrs: Vec<Attribute>)
4284 -> PResult<'a, StructField> {
4285 let name = self.parse_ident()?;
4286 self.expect(&token::Colon)?;
4287 let ty = self.parse_ty()?;
4289 span: lo.to(self.prev_span),
4292 id: ast::DUMMY_NODE_ID,
4298 /// Emit an expected item after attributes error.
4299 fn expected_item_err(&self, attrs: &[Attribute]) {
4300 let message = match attrs.last() {
4301 Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
4302 _ => "expected item after attributes",
4305 self.span_err(self.prev_span, message);
4308 /// Parse a statement. This stops just before trailing semicolons on everything but items.
4309 /// e.g. a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
4310 pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
4311 Ok(self.parse_stmt_(true))
4314 // Eat tokens until we can be relatively sure we reached the end of the
4315 // statement. This is something of a best-effort heuristic.
4317 // We terminate when we find an unmatched `}` (without consuming it).
4318 fn recover_stmt(&mut self) {
4319 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
4322 // If `break_on_semi` is `Break`, then we will stop consuming tokens after
4323 // finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
4324 // approximate - it can mean we break too early due to macros, but that
4325 // should only lead to sub-optimal recovery, not inaccurate parsing).
4327 // If `break_on_block` is `Break`, then we will stop consuming tokens
4328 // after finding (and consuming) a brace-delimited block.
4329 fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) {
4330 let mut brace_depth = 0;
4331 let mut bracket_depth = 0;
4332 let mut in_block = false;
4333 debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
4334 break_on_semi, break_on_block);
4336 debug!("recover_stmt_ loop {:?}", self.token);
4338 token::OpenDelim(token::DelimToken::Brace) => {
4341 if break_on_block == BlockMode::Break &&
4343 bracket_depth == 0 {
4347 token::OpenDelim(token::DelimToken::Bracket) => {
4351 token::CloseDelim(token::DelimToken::Brace) => {
4352 if brace_depth == 0 {
4353 debug!("recover_stmt_ return - close delim {:?}", self.token);
4358 if in_block && bracket_depth == 0 && brace_depth == 0 {
4359 debug!("recover_stmt_ return - block end {:?}", self.token);
4363 token::CloseDelim(token::DelimToken::Bracket) => {
4365 if bracket_depth < 0 {
4371 debug!("recover_stmt_ return - Eof");
4376 if break_on_semi == SemiColonMode::Break &&
4378 bracket_depth == 0 {
4379 debug!("recover_stmt_ return - Semi");
4390 fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
4391 self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
4393 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4398 fn is_async_block(&mut self) -> bool {
4399 self.token.is_keyword(keywords::Async) &&
4402 self.look_ahead(1, |t| t.is_keyword(keywords::Move)) &&
4403 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
4405 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
4410 fn is_catch_expr(&mut self) -> bool {
4411 self.token.is_keyword(keywords::Do) &&
4412 self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) &&
4413 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
4415 // prevent `while catch {} {}`, `if catch {} {} else {}`, etc.
4416 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4419 fn is_union_item(&self) -> bool {
4420 self.token.is_keyword(keywords::Union) &&
4421 self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
4424 fn is_crate_vis(&self) -> bool {
4425 self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
4428 fn is_extern_non_path(&self) -> bool {
4429 self.token.is_keyword(keywords::Extern) && self.look_ahead(1, |t| t != &token::ModSep)
4432 fn is_existential_type_decl(&self) -> bool {
4433 self.token.is_keyword(keywords::Existential) &&
4434 self.look_ahead(1, |t| t.is_keyword(keywords::Type))
4437 fn is_auto_trait_item(&mut self) -> bool {
4439 (self.token.is_keyword(keywords::Auto)
4440 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
4441 || // unsafe auto trait
4442 (self.token.is_keyword(keywords::Unsafe) &&
4443 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) &&
4444 self.look_ahead(2, |t| t.is_keyword(keywords::Trait)))
4447 fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span)
4448 -> PResult<'a, Option<P<Item>>> {
4449 let token_lo = self.span;
4450 let (ident, def) = match self.token {
4451 token::Ident(ident, false) if ident.name == keywords::Macro.name() => {
4453 let ident = self.parse_ident()?;
4454 let tokens = if self.check(&token::OpenDelim(token::Brace)) {
4455 match self.parse_token_tree() {
4456 TokenTree::Delimited(_, ref delimited) => delimited.stream(),
4457 _ => unreachable!(),
4459 } else if self.check(&token::OpenDelim(token::Paren)) {
4460 let args = self.parse_token_tree();
4461 let body = if self.check(&token::OpenDelim(token::Brace)) {
4462 self.parse_token_tree()
4467 TokenStream::concat(vec![
4469 TokenTree::Token(token_lo.to(self.prev_span), token::FatArrow).into(),
4477 (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
4479 token::Ident(ident, _) if ident.name == "macro_rules" &&
4480 self.look_ahead(1, |t| *t == token::Not) => {
4481 let prev_span = self.prev_span;
4482 self.complain_if_pub_macro(&vis.node, prev_span);
4486 let ident = self.parse_ident()?;
4487 let (delim, tokens) = self.expect_delimited_token_tree()?;
4488 if delim != MacDelimiter::Brace {
4489 if !self.eat(&token::Semi) {
4490 let msg = "macros that expand to items must either \
4491 be surrounded with braces or followed by a semicolon";
4492 self.span_err(self.prev_span, msg);
4496 (ident, ast::MacroDef { tokens: tokens, legacy: true })
4498 _ => return Ok(None),
4501 let span = lo.to(self.prev_span);
4502 Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
4505 fn parse_stmt_without_recovery(&mut self,
4506 macro_legacy_warnings: bool)
4507 -> PResult<'a, Option<Stmt>> {
4508 maybe_whole!(self, NtStmt, |x| Some(x));
4510 let attrs = self.parse_outer_attributes()?;
4513 Ok(Some(if self.eat_keyword(keywords::Let) {
4515 id: ast::DUMMY_NODE_ID,
4516 node: StmtKind::Local(self.parse_local(attrs.into())?),
4517 span: lo.to(self.prev_span),
4519 } else if let Some(macro_def) = self.eat_macro_def(
4521 &source_map::respan(lo, VisibilityKind::Inherited),
4525 id: ast::DUMMY_NODE_ID,
4526 node: StmtKind::Item(macro_def),
4527 span: lo.to(self.prev_span),
4529 // Starts like a simple path, being careful to avoid contextual keywords
4530 // such as a union items, item with `crate` visibility or auto trait items.
4531 // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
4532 // like a path (1 token), but it fact not a path.
4533 // `union::b::c` - path, `union U { ... }` - not a path.
4534 // `crate::b::c` - path, `crate struct S;` - not a path.
4535 // `extern::b::c` - path, `extern crate c;` - not a path.
4536 } else if self.token.is_path_start() &&
4537 !self.token.is_qpath_start() &&
4538 !self.is_union_item() &&
4539 !self.is_crate_vis() &&
4540 !self.is_extern_non_path() &&
4541 !self.is_existential_type_decl() &&
4542 !self.is_auto_trait_item() {
4543 let pth = self.parse_path(PathStyle::Expr)?;
4545 if !self.eat(&token::Not) {
4546 let expr = if self.check(&token::OpenDelim(token::Brace)) {
4547 self.parse_struct_expr(lo, pth, ThinVec::new())?
4549 let hi = self.prev_span;
4550 self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), ThinVec::new())
4553 let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
4554 let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
4555 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
4558 return Ok(Some(Stmt {
4559 id: ast::DUMMY_NODE_ID,
4560 node: StmtKind::Expr(expr),
4561 span: lo.to(self.prev_span),
4565 // it's a macro invocation
4566 let id = match self.token {
4567 token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier
4568 _ => self.parse_ident()?,
4571 // check that we're pointing at delimiters (need to check
4572 // again after the `if`, because of `parse_ident`
4573 // consuming more tokens).
4575 token::OpenDelim(_) => {}
4577 // we only expect an ident if we didn't parse one
4579 let ident_str = if id.name == keywords::Invalid.name() {
4584 let tok_str = self.this_token_to_string();
4585 let mut err = self.fatal(&format!("expected {}`(` or `{{`, found `{}`",
4588 err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str));
4593 let (delim, tts) = self.expect_delimited_token_tree()?;
4594 let hi = self.prev_span;
4596 let style = if delim == MacDelimiter::Brace {
4597 MacStmtStyle::Braces
4599 MacStmtStyle::NoBraces
4602 if id.name == keywords::Invalid.name() {
4603 let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim });
4604 let node = if delim == MacDelimiter::Brace ||
4605 self.token == token::Semi || self.token == token::Eof {
4606 StmtKind::Mac(P((mac, style, attrs.into())))
4608 // We used to incorrectly stop parsing macro-expanded statements here.
4609 // If the next token will be an error anyway but could have parsed with the
4610 // earlier behavior, stop parsing here and emit a warning to avoid breakage.
4611 else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token {
4612 // These can continue an expression, so we can't stop parsing and warn.
4613 token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
4614 token::BinOp(token::Minus) | token::BinOp(token::Star) |
4615 token::BinOp(token::And) | token::BinOp(token::Or) |
4616 token::AndAnd | token::OrOr |
4617 token::DotDot | token::DotDotDot | token::DotDotEq => false,
4620 self.warn_missing_semicolon();
4621 StmtKind::Mac(P((mac, style, attrs.into())))
4623 let e = self.mk_mac_expr(lo.to(hi), mac.node, ThinVec::new());
4624 let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
4625 let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
4629 id: ast::DUMMY_NODE_ID,
4634 // if it has a special ident, it's definitely an item
4636 // Require a semicolon or braces.
4637 if style != MacStmtStyle::Braces {
4638 if !self.eat(&token::Semi) {
4639 self.span_err(self.prev_span,
4640 "macros that expand to items must \
4641 either be surrounded with braces or \
4642 followed by a semicolon");
4645 let span = lo.to(hi);
4647 id: ast::DUMMY_NODE_ID,
4649 node: StmtKind::Item({
4651 span, id /*id is good here*/,
4652 ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })),
4653 respan(lo, VisibilityKind::Inherited),
4659 // FIXME: Bad copy of attrs
4660 let old_directory_ownership =
4661 mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
4662 let item = self.parse_item_(attrs.clone(), false, true)?;
4663 self.directory.ownership = old_directory_ownership;
4667 id: ast::DUMMY_NODE_ID,
4668 span: lo.to(i.span),
4669 node: StmtKind::Item(i),
4672 let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
4673 if !attrs.is_empty() {
4674 if s.prev_token_kind == PrevTokenKind::DocComment {
4675 s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
4676 } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
4677 s.span_err(s.span, "expected statement after outer attribute");
4682 // Do not attempt to parse an expression if we're done here.
4683 if self.token == token::Semi {
4684 unused_attrs(&attrs, self);
4689 if self.token == token::CloseDelim(token::Brace) {
4690 unused_attrs(&attrs, self);
4694 // Remainder are line-expr stmts.
4695 let e = self.parse_expr_res(
4696 Restrictions::STMT_EXPR, Some(attrs.into()))?;
4698 id: ast::DUMMY_NODE_ID,
4699 span: lo.to(e.span),
4700 node: StmtKind::Expr(e),
4707 /// Is this expression a successfully-parsed statement?
4708 fn expr_is_complete(&mut self, e: &Expr) -> bool {
4709 self.restrictions.contains(Restrictions::STMT_EXPR) &&
4710 !classify::expr_requires_semi_to_be_stmt(e)
4713 /// Parse a block. No inner attrs are allowed.
4714 pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
4715 maybe_whole!(self, NtBlock, |x| x);
4719 if !self.eat(&token::OpenDelim(token::Brace)) {
4721 let tok = self.this_token_to_string();
4722 let mut do_not_suggest_help = false;
4723 let mut e = self.span_fatal(sp, &format!("expected `{{`, found `{}`", tok));
4724 if self.token.is_keyword(keywords::In) || self.token == token::Colon {
4725 do_not_suggest_help = true;
4726 e.span_label(sp, "expected `{`");
4729 // Check to see if the user has written something like
4734 // Which is valid in other languages, but not Rust.
4735 match self.parse_stmt_without_recovery(false) {
4737 if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
4738 || do_not_suggest_help {
4739 // if the next token is an open brace (e.g., `if a b {`), the place-
4740 // inside-a-block suggestion would be more likely wrong than right
4743 let mut stmt_span = stmt.span;
4744 // expand the span to include the semicolon, if it exists
4745 if self.eat(&token::Semi) {
4746 stmt_span = stmt_span.with_hi(self.prev_span.hi());
4748 let sugg = pprust::to_string(|s| {
4749 use print::pprust::{PrintState, INDENT_UNIT};
4750 s.ibox(INDENT_UNIT)?;
4752 s.print_stmt(&stmt)?;
4753 s.bclose_maybe_open(stmt.span, INDENT_UNIT, false)
4755 e.span_suggestion_with_applicability(
4757 "try placing this code inside a block",
4759 // speculative, has been misleading in the past (closed Issue #46836)
4760 Applicability::MaybeIncorrect
4764 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4765 self.cancel(&mut e);
4772 self.parse_block_tail(lo, BlockCheckMode::Default)
4775 /// Parse a block. Inner attrs are allowed.
4776 fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
4777 maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
4780 self.expect(&token::OpenDelim(token::Brace))?;
4781 Ok((self.parse_inner_attributes()?,
4782 self.parse_block_tail(lo, BlockCheckMode::Default)?))
4785 /// Parse the rest of a block expression or function body
4786 /// Precondition: already parsed the '{'.
4787 fn parse_block_tail(&mut self, lo: Span, s: BlockCheckMode) -> PResult<'a, P<Block>> {
4788 let mut stmts = vec![];
4789 let mut recovered = false;
4791 while !self.eat(&token::CloseDelim(token::Brace)) {
4792 let stmt = match self.parse_full_stmt(false) {
4795 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
4796 self.eat(&token::CloseDelim(token::Brace));
4802 if let Some(stmt) = stmt {
4804 } else if self.token == token::Eof {
4807 // Found only `;` or `}`.
4813 id: ast::DUMMY_NODE_ID,
4815 span: lo.to(self.prev_span),
4820 /// Parse a statement, including the trailing semicolon.
4821 crate fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
4822 // skip looking for a trailing semicolon when we have an interpolated statement
4823 maybe_whole!(self, NtStmt, |x| Some(x));
4825 let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
4827 None => return Ok(None),
4831 StmtKind::Expr(ref expr) if self.token != token::Eof => {
4832 // expression without semicolon
4833 if classify::expr_requires_semi_to_be_stmt(expr) {
4834 // Just check for errors and recover; do not eat semicolon yet.
4836 self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
4839 self.recover_stmt();
4843 StmtKind::Local(..) => {
4844 // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
4845 if macro_legacy_warnings && self.token != token::Semi {
4846 self.warn_missing_semicolon();
4848 self.expect_one_of(&[], &[token::Semi])?;
4854 if self.eat(&token::Semi) {
4855 stmt = stmt.add_trailing_semicolon();
4858 stmt.span = stmt.span.with_hi(self.prev_span.hi());
4862 fn warn_missing_semicolon(&self) {
4863 self.diagnostic().struct_span_warn(self.span, {
4864 &format!("expected `;`, found `{}`", self.this_token_to_string())
4866 "This was erroneously allowed and will become a hard error in a future release"
4870 fn err_dotdotdot_syntax(&self, span: Span) {
4871 self.diagnostic().struct_span_err(span, {
4872 "unexpected token: `...`"
4873 }).span_suggestion_with_applicability(
4874 span, "use `..` for an exclusive range", "..".to_owned(),
4875 Applicability::MaybeIncorrect
4876 ).span_suggestion_with_applicability(
4877 span, "or `..=` for an inclusive range", "..=".to_owned(),
4878 Applicability::MaybeIncorrect
4882 // Parse bounds of a type parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
4883 // BOUND = TY_BOUND | LT_BOUND
4884 // LT_BOUND = LIFETIME (e.g. `'a`)
4885 // TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
4886 // TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g. `?for<'a: 'b> m::Trait<'a>`)
4887 fn parse_generic_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, GenericBounds> {
4888 let mut bounds = Vec::new();
4890 // This needs to be synchronized with `Token::can_begin_bound`.
4891 let is_bound_start = self.check_path() || self.check_lifetime() ||
4892 self.check(&token::Question) ||
4893 self.check_keyword(keywords::For) ||
4894 self.check(&token::OpenDelim(token::Paren));
4897 let has_parens = self.eat(&token::OpenDelim(token::Paren));
4898 let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
4899 if self.token.is_lifetime() {
4900 if let Some(question_span) = question {
4901 self.span_err(question_span,
4902 "`?` may only modify trait bounds, not lifetime bounds");
4904 bounds.push(GenericBound::Outlives(self.expect_lifetime()));
4906 self.expect(&token::CloseDelim(token::Paren))?;
4907 self.span_err(self.prev_span,
4908 "parenthesized lifetime bounds are not supported");
4911 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
4912 let path = self.parse_path(PathStyle::Type)?;
4914 self.expect(&token::CloseDelim(token::Paren))?;
4916 let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span));
4917 let modifier = if question.is_some() {
4918 TraitBoundModifier::Maybe
4920 TraitBoundModifier::None
4922 bounds.push(GenericBound::Trait(poly_trait, modifier));
4928 if !allow_plus || !self.eat_plus() {
4936 fn parse_generic_bounds(&mut self) -> PResult<'a, GenericBounds> {
4937 self.parse_generic_bounds_common(true)
4940 // Parse bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
4941 // BOUND = LT_BOUND (e.g. `'a`)
4942 fn parse_lt_param_bounds(&mut self) -> GenericBounds {
4943 let mut lifetimes = Vec::new();
4944 while self.check_lifetime() {
4945 lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
4947 if !self.eat_plus() {
4954 /// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
4955 fn parse_ty_param(&mut self,
4956 preceding_attrs: Vec<Attribute>)
4957 -> PResult<'a, GenericParam> {
4958 let ident = self.parse_ident()?;
4960 // Parse optional colon and param bounds.
4961 let bounds = if self.eat(&token::Colon) {
4962 self.parse_generic_bounds()?
4967 let default = if self.eat(&token::Eq) {
4968 Some(self.parse_ty()?)
4975 id: ast::DUMMY_NODE_ID,
4976 attrs: preceding_attrs.into(),
4978 kind: GenericParamKind::Type {
4984 /// Parses the following grammar:
4985 /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
4986 fn parse_trait_item_assoc_ty(&mut self)
4987 -> PResult<'a, (Ident, TraitItemKind, ast::Generics)> {
4988 let ident = self.parse_ident()?;
4989 let mut generics = self.parse_generics()?;
4991 // Parse optional colon and param bounds.
4992 let bounds = if self.eat(&token::Colon) {
4993 self.parse_generic_bounds()?
4997 generics.where_clause = self.parse_where_clause()?;
4999 let default = if self.eat(&token::Eq) {
5000 Some(self.parse_ty()?)
5004 self.expect(&token::Semi)?;
5006 Ok((ident, TraitItemKind::Type(bounds, default), generics))
5009 /// Parses (possibly empty) list of lifetime and type parameters, possibly including
5010 /// trailing comma and erroneous trailing attributes.
5011 crate fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
5012 let mut params = Vec::new();
5013 let mut seen_ty_param = false;
5015 let attrs = self.parse_outer_attributes()?;
5016 if self.check_lifetime() {
5017 let lifetime = self.expect_lifetime();
5018 // Parse lifetime parameter.
5019 let bounds = if self.eat(&token::Colon) {
5020 self.parse_lt_param_bounds()
5024 params.push(ast::GenericParam {
5025 ident: lifetime.ident,
5027 attrs: attrs.into(),
5029 kind: ast::GenericParamKind::Lifetime,
5032 self.span_err(self.prev_span,
5033 "lifetime parameters must be declared prior to type parameters");
5035 } else if self.check_ident() {
5036 // Parse type parameter.
5037 params.push(self.parse_ty_param(attrs)?);
5038 seen_ty_param = true;
5040 // Check for trailing attributes and stop parsing.
5041 if !attrs.is_empty() {
5042 let param_kind = if seen_ty_param { "type" } else { "lifetime" };
5043 self.span_err(attrs[0].span,
5044 &format!("trailing attribute after {} parameters", param_kind));
5049 if !self.eat(&token::Comma) {
5056 /// Parse a set of optional generic type parameter declarations. Where
5057 /// clauses are not parsed here, and must be added later via
5058 /// `parse_where_clause()`.
5060 /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
5061 /// | ( < lifetimes , typaramseq ( , )? > )
5062 /// where typaramseq = ( typaram ) | ( typaram , typaramseq )
5063 fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
5064 maybe_whole!(self, NtGenerics, |x| x);
5066 let span_lo = self.span;
5068 let params = self.parse_generic_params()?;
5072 where_clause: WhereClause {
5073 id: ast::DUMMY_NODE_ID,
5074 predicates: Vec::new(),
5075 span: syntax_pos::DUMMY_SP,
5077 span: span_lo.to(self.prev_span),
5080 Ok(ast::Generics::default())
5084 /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
5085 /// possibly including trailing comma.
5086 fn parse_generic_args(&mut self)
5087 -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
5088 let mut args = Vec::new();
5089 let mut bindings = Vec::new();
5090 let mut seen_type = false;
5091 let mut seen_binding = false;
5093 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5094 // Parse lifetime argument.
5095 args.push(GenericArg::Lifetime(self.expect_lifetime()));
5096 if seen_type || seen_binding {
5097 self.span_err(self.prev_span,
5098 "lifetime parameters must be declared prior to type parameters");
5100 } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
5101 // Parse associated type binding.
5103 let ident = self.parse_ident()?;
5105 let ty = self.parse_ty()?;
5106 bindings.push(TypeBinding {
5107 id: ast::DUMMY_NODE_ID,
5110 span: lo.to(self.prev_span),
5112 seen_binding = true;
5113 } else if self.check_type() {
5114 // Parse type argument.
5115 let ty_param = self.parse_ty()?;
5117 self.span_err(ty_param.span,
5118 "type parameters must be declared prior to associated type bindings");
5120 args.push(GenericArg::Type(ty_param));
5126 if !self.eat(&token::Comma) {
5130 Ok((args, bindings))
5133 /// Parses an optional `where` clause and places it in `generics`.
5135 /// ```ignore (only-for-syntax-highlight)
5136 /// where T : Trait<U, V> + 'b, 'a : 'b
5138 fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
5139 maybe_whole!(self, NtWhereClause, |x| x);
5141 let mut where_clause = WhereClause {
5142 id: ast::DUMMY_NODE_ID,
5143 predicates: Vec::new(),
5144 span: syntax_pos::DUMMY_SP,
5147 if !self.eat_keyword(keywords::Where) {
5148 return Ok(where_clause);
5150 let lo = self.prev_span;
5152 // We are considering adding generics to the `where` keyword as an alternative higher-rank
5153 // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
5154 // change we parse those generics now, but report an error.
5155 if self.choose_generics_over_qpath() {
5156 let generics = self.parse_generics()?;
5157 self.span_err(generics.span,
5158 "generic parameters on `where` clauses are reserved for future use");
5163 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5164 let lifetime = self.expect_lifetime();
5165 // Bounds starting with a colon are mandatory, but possibly empty.
5166 self.expect(&token::Colon)?;
5167 let bounds = self.parse_lt_param_bounds();
5168 where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
5169 ast::WhereRegionPredicate {
5170 span: lo.to(self.prev_span),
5175 } else if self.check_type() {
5176 // Parse optional `for<'a, 'b>`.
5177 // This `for` is parsed greedily and applies to the whole predicate,
5178 // the bounded type can have its own `for` applying only to it.
5179 // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/>
5180 // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/>
5181 // Example 3: for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /*ok*/, 'b /*not ok*/>
5182 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5184 // Parse type with mandatory colon and (possibly empty) bounds,
5185 // or with mandatory equality sign and the second type.
5186 let ty = self.parse_ty()?;
5187 if self.eat(&token::Colon) {
5188 let bounds = self.parse_generic_bounds()?;
5189 where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
5190 ast::WhereBoundPredicate {
5191 span: lo.to(self.prev_span),
5192 bound_generic_params: lifetime_defs,
5197 // FIXME: Decide what should be used here, `=` or `==`.
5198 // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
5199 } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
5200 let rhs_ty = self.parse_ty()?;
5201 where_clause.predicates.push(ast::WherePredicate::EqPredicate(
5202 ast::WhereEqPredicate {
5203 span: lo.to(self.prev_span),
5206 id: ast::DUMMY_NODE_ID,
5210 return self.unexpected();
5216 if !self.eat(&token::Comma) {
5221 where_clause.span = lo.to(self.prev_span);
5225 fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
5226 -> PResult<'a, (Vec<Arg> , bool)> {
5228 let mut variadic = false;
5229 let args: Vec<Option<Arg>> =
5230 self.parse_unspanned_seq(
5231 &token::OpenDelim(token::Paren),
5232 &token::CloseDelim(token::Paren),
5233 SeqSep::trailing_allowed(token::Comma),
5235 if p.token == token::DotDotDot {
5239 if p.token != token::CloseDelim(token::Paren) {
5242 "`...` must be last in argument list for variadic function");
5246 let span = p.prev_span;
5247 if p.token == token::CloseDelim(token::Paren) {
5248 // continue parsing to present any further errors
5251 "only foreign functions are allowed to be variadic"
5253 Ok(Some(dummy_arg(span)))
5255 // this function definition looks beyond recovery, stop parsing
5257 "only foreign functions are allowed to be variadic");
5262 match p.parse_arg_general(named_args) {
5263 Ok(arg) => Ok(Some(arg)),
5266 let lo = p.prev_span;
5267 // Skip every token until next possible arg or end.
5268 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
5269 // Create a placeholder argument for proper arg count (#34264).
5270 let span = lo.to(p.prev_span);
5271 Ok(Some(dummy_arg(span)))
5278 let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
5280 if variadic && args.is_empty() {
5282 "variadic function must be declared with at least one named argument");
5285 Ok((args, variadic))
5288 /// Parse the argument list and result type of a function declaration
5289 fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
5291 let (args, variadic) = self.parse_fn_args(true, allow_variadic)?;
5292 let ret_ty = self.parse_ret_ty(true)?;
5301 /// Returns the parsed optional self argument and whether a self shortcut was used.
5302 fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
5303 let expect_ident = |this: &mut Self| match this.token {
5304 // Preserve hygienic context.
5305 token::Ident(ident, _) =>
5306 { let span = this.span; this.bump(); Ident::new(ident.name, span) }
5309 let isolated_self = |this: &mut Self, n| {
5310 this.look_ahead(n, |t| t.is_keyword(keywords::SelfValue)) &&
5311 this.look_ahead(n + 1, |t| t != &token::ModSep)
5314 // Parse optional self parameter of a method.
5315 // Only a limited set of initial token sequences is considered self parameters, anything
5316 // else is parsed as a normal function parameter list, so some lookahead is required.
5317 let eself_lo = self.span;
5318 let (eself, eself_ident, eself_hi) = match self.token {
5319 token::BinOp(token::And) => {
5325 (if isolated_self(self, 1) {
5327 SelfKind::Region(None, Mutability::Immutable)
5328 } else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
5329 isolated_self(self, 2) {
5332 SelfKind::Region(None, Mutability::Mutable)
5333 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5334 isolated_self(self, 2) {
5336 let lt = self.expect_lifetime();
5337 SelfKind::Region(Some(lt), Mutability::Immutable)
5338 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5339 self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
5340 isolated_self(self, 3) {
5342 let lt = self.expect_lifetime();
5344 SelfKind::Region(Some(lt), Mutability::Mutable)
5347 }, expect_ident(self), self.prev_span)
5349 token::BinOp(token::Star) => {
5354 // Emit special error for `self` cases.
5355 (if isolated_self(self, 1) {
5357 self.span_err(self.span, "cannot pass `self` by raw pointer");
5358 SelfKind::Value(Mutability::Immutable)
5359 } else if self.look_ahead(1, |t| t.is_mutability()) &&
5360 isolated_self(self, 2) {
5363 self.span_err(self.span, "cannot pass `self` by raw pointer");
5364 SelfKind::Value(Mutability::Immutable)
5367 }, expect_ident(self), self.prev_span)
5369 token::Ident(..) => {
5370 if isolated_self(self, 0) {
5373 let eself_ident = expect_ident(self);
5374 let eself_hi = self.prev_span;
5375 (if self.eat(&token::Colon) {
5376 let ty = self.parse_ty()?;
5377 SelfKind::Explicit(ty, Mutability::Immutable)
5379 SelfKind::Value(Mutability::Immutable)
5380 }, eself_ident, eself_hi)
5381 } else if self.token.is_keyword(keywords::Mut) &&
5382 isolated_self(self, 1) {
5386 let eself_ident = expect_ident(self);
5387 let eself_hi = self.prev_span;
5388 (if self.eat(&token::Colon) {
5389 let ty = self.parse_ty()?;
5390 SelfKind::Explicit(ty, Mutability::Mutable)
5392 SelfKind::Value(Mutability::Mutable)
5393 }, eself_ident, eself_hi)
5398 _ => return Ok(None),
5401 let eself = source_map::respan(eself_lo.to(eself_hi), eself);
5402 Ok(Some(Arg::from_self(eself, eself_ident)))
5405 /// Parse the parameter list and result type of a function that may have a `self` parameter.
5406 fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>>
5407 where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
5409 self.expect(&token::OpenDelim(token::Paren))?;
5411 // Parse optional self argument
5412 let self_arg = self.parse_self_arg()?;
5414 // Parse the rest of the function parameter list.
5415 let sep = SeqSep::trailing_allowed(token::Comma);
5416 let fn_inputs = if let Some(self_arg) = self_arg {
5417 if self.check(&token::CloseDelim(token::Paren)) {
5419 } else if self.eat(&token::Comma) {
5420 let mut fn_inputs = vec![self_arg];
5421 fn_inputs.append(&mut self.parse_seq_to_before_end(
5422 &token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5426 return self.unexpected();
5429 self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5432 // Parse closing paren and return type.
5433 self.expect(&token::CloseDelim(token::Paren))?;
5436 output: self.parse_ret_ty(true)?,
5441 // parse the |arg, arg| header on a lambda
5442 fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
5443 let inputs_captures = {
5444 if self.eat(&token::OrOr) {
5447 self.expect(&token::BinOp(token::Or))?;
5448 let args = self.parse_seq_to_before_tokens(
5449 &[&token::BinOp(token::Or), &token::OrOr],
5450 SeqSep::trailing_allowed(token::Comma),
5451 TokenExpectType::NoExpect,
5452 |p| p.parse_fn_block_arg()
5458 let output = self.parse_ret_ty(true)?;
5461 inputs: inputs_captures,
5467 /// Parse the name and optional generic types of a function header.
5468 fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
5469 let id = self.parse_ident()?;
5470 let generics = self.parse_generics()?;
5474 fn mk_item(&mut self, span: Span, ident: Ident, node: ItemKind, vis: Visibility,
5475 attrs: Vec<Attribute>) -> P<Item> {
5479 id: ast::DUMMY_NODE_ID,
5487 /// Parse an item-position function declaration.
5488 fn parse_item_fn(&mut self,
5491 constness: Spanned<Constness>,
5493 -> PResult<'a, ItemInfo> {
5494 let (ident, mut generics) = self.parse_fn_header()?;
5495 let decl = self.parse_fn_decl(false)?;
5496 generics.where_clause = self.parse_where_clause()?;
5497 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5498 let header = FnHeader { unsafety, asyncness, constness, abi };
5499 Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
5502 /// true if we are looking at `const ID`, false for things like `const fn` etc
5503 fn is_const_item(&mut self) -> bool {
5504 self.token.is_keyword(keywords::Const) &&
5505 !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
5506 !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
5509 /// parses all the "front matter" for a `fn` declaration, up to
5510 /// and including the `fn` keyword:
5514 /// - `const unsafe fn`
5517 fn parse_fn_front_matter(&mut self)
5525 let is_const_fn = self.eat_keyword(keywords::Const);
5526 let const_span = self.prev_span;
5527 let unsafety = self.parse_unsafety();
5528 let asyncness = self.parse_asyncness();
5529 let (constness, unsafety, abi) = if is_const_fn {
5530 (respan(const_span, Constness::Const), unsafety, Abi::Rust)
5532 let abi = if self.eat_keyword(keywords::Extern) {
5533 self.parse_opt_abi()?.unwrap_or(Abi::C)
5537 (respan(self.prev_span, Constness::NotConst), unsafety, abi)
5539 self.expect_keyword(keywords::Fn)?;
5540 Ok((constness, unsafety, asyncness, abi))
5543 /// Parse an impl item.
5544 pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
5545 maybe_whole!(self, NtImplItem, |x| x);
5546 let attrs = self.parse_outer_attributes()?;
5547 let (mut item, tokens) = self.collect_tokens(|this| {
5548 this.parse_impl_item_(at_end, attrs)
5551 // See `parse_item` for why this clause is here.
5552 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
5553 item.tokens = Some(tokens);
5558 fn parse_impl_item_(&mut self,
5560 mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> {
5562 let vis = self.parse_visibility(false)?;
5563 let defaultness = self.parse_defaultness();
5564 let (name, node, generics) = if let Some(type_) = self.eat_type() {
5565 let (name, alias, generics) = type_?;
5566 let kind = match alias {
5567 AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ),
5568 AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds),
5570 (name, kind, generics)
5571 } else if self.is_const_item() {
5572 // This parses the grammar:
5573 // ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
5574 self.expect_keyword(keywords::Const)?;
5575 let name = self.parse_ident()?;
5576 self.expect(&token::Colon)?;
5577 let typ = self.parse_ty()?;
5578 self.expect(&token::Eq)?;
5579 let expr = self.parse_expr()?;
5580 self.expect(&token::Semi)?;
5581 (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default())
5583 let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?;
5584 attrs.extend(inner_attrs);
5585 (name, node, generics)
5589 id: ast::DUMMY_NODE_ID,
5590 span: lo.to(self.prev_span),
5601 fn complain_if_pub_macro(&mut self, vis: &VisibilityKind, sp: Span) {
5602 if let Err(mut err) = self.complain_if_pub_macro_diag(vis, sp) {
5607 fn complain_if_pub_macro_diag(&mut self, vis: &VisibilityKind, sp: Span) -> PResult<'a, ()> {
5609 VisibilityKind::Inherited => Ok(()),
5611 let is_macro_rules: bool = match self.token {
5612 token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"),
5616 let mut err = self.diagnostic()
5617 .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
5618 err.span_suggestion_with_applicability(
5620 "try exporting the macro",
5621 "#[macro_export]".to_owned(),
5622 Applicability::MaybeIncorrect // speculative
5626 let mut err = self.diagnostic()
5627 .struct_span_err(sp, "can't qualify macro invocation with `pub`");
5628 err.help("try adjusting the macro to put `pub` inside the invocation");
5635 fn missing_assoc_item_kind_err(&mut self, item_type: &str, prev_span: Span)
5636 -> DiagnosticBuilder<'a>
5638 let expected_kinds = if item_type == "extern" {
5639 "missing `fn`, `type`, or `static`"
5641 "missing `fn`, `type`, or `const`"
5644 // Given this code `path(`, it seems like this is not
5645 // setting the visibility of a macro invocation, but rather
5646 // a mistyped method declaration.
5647 // Create a diagnostic pointing out that `fn` is missing.
5649 // x | pub path(&self) {
5650 // | ^ missing `fn`, `type`, or `const`
5652 // ^^ `sp` below will point to this
5653 let sp = prev_span.between(self.prev_span);
5654 let mut err = self.diagnostic().struct_span_err(
5656 &format!("{} for {}-item declaration",
5657 expected_kinds, item_type));
5658 err.span_label(sp, expected_kinds);
5662 /// Parse a method or a macro invocation in a trait impl.
5663 fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
5664 -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics,
5665 ast::ImplItemKind)> {
5666 // code copied from parse_macro_use_or_failure... abstraction!
5667 if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
5669 Ok((keywords::Invalid.ident(), vec![], ast::Generics::default(),
5670 ast::ImplItemKind::Macro(mac)))
5672 let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
5673 let ident = self.parse_ident()?;
5674 let mut generics = self.parse_generics()?;
5675 let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
5676 generics.where_clause = self.parse_where_clause()?;
5678 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5679 let header = ast::FnHeader { abi, unsafety, constness, asyncness };
5680 Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
5681 ast::MethodSig { header, decl },
5687 /// Parse `trait Foo { ... }` or `trait Foo = Bar;`
5688 fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5689 let ident = self.parse_ident()?;
5690 let mut tps = self.parse_generics()?;
5692 // Parse optional colon and supertrait bounds.
5693 let bounds = if self.eat(&token::Colon) {
5694 self.parse_generic_bounds()?
5699 if self.eat(&token::Eq) {
5700 // it's a trait alias
5701 let bounds = self.parse_generic_bounds()?;
5702 tps.where_clause = self.parse_where_clause()?;
5703 self.expect(&token::Semi)?;
5704 if unsafety != Unsafety::Normal {
5705 self.span_err(self.prev_span, "trait aliases cannot be unsafe");
5707 Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
5709 // it's a normal trait
5710 tps.where_clause = self.parse_where_clause()?;
5711 self.expect(&token::OpenDelim(token::Brace))?;
5712 let mut trait_items = vec![];
5713 while !self.eat(&token::CloseDelim(token::Brace)) {
5714 let mut at_end = false;
5715 match self.parse_trait_item(&mut at_end) {
5716 Ok(item) => trait_items.push(item),
5720 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5725 Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
5729 fn choose_generics_over_qpath(&self) -> bool {
5730 // There's an ambiguity between generic parameters and qualified paths in impls.
5731 // If we see `<` it may start both, so we have to inspect some following tokens.
5732 // The following combinations can only start generics,
5733 // but not qualified paths (with one exception):
5734 // `<` `>` - empty generic parameters
5735 // `<` `#` - generic parameters with attributes
5736 // `<` (LIFETIME|IDENT) `>` - single generic parameter
5737 // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
5738 // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
5739 // `<` (LIFETIME|IDENT) `=` - generic parameter with a default
5740 // The only truly ambiguous case is
5741 // `<` IDENT `>` `::` IDENT ...
5742 // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
5743 // because this is what almost always expected in practice, qualified paths in impls
5744 // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
5745 self.token == token::Lt &&
5746 (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
5747 self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
5748 self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
5749 t == &token::Colon || t == &token::Eq))
5752 fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
5753 self.expect(&token::OpenDelim(token::Brace))?;
5754 let attrs = self.parse_inner_attributes()?;
5756 let mut impl_items = Vec::new();
5757 while !self.eat(&token::CloseDelim(token::Brace)) {
5758 let mut at_end = false;
5759 match self.parse_impl_item(&mut at_end) {
5760 Ok(impl_item) => impl_items.push(impl_item),
5764 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5769 Ok((impl_items, attrs))
5772 /// Parses an implementation item, `impl` keyword is already parsed.
5773 /// impl<'a, T> TYPE { /* impl items */ }
5774 /// impl<'a, T> TRAIT for TYPE { /* impl items */ }
5775 /// impl<'a, T> !TRAIT for TYPE { /* impl items */ }
5776 /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
5777 /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
5778 /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
5779 fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
5780 -> PResult<'a, ItemInfo> {
5781 // First, parse generic parameters if necessary.
5782 let mut generics = if self.choose_generics_over_qpath() {
5783 self.parse_generics()?
5785 ast::Generics::default()
5788 // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
5789 let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
5791 ast::ImplPolarity::Negative
5793 ast::ImplPolarity::Positive
5796 // Parse both types and traits as a type, then reinterpret if necessary.
5797 let ty_first = self.parse_ty()?;
5799 // If `for` is missing we try to recover.
5800 let has_for = self.eat_keyword(keywords::For);
5801 let missing_for_span = self.prev_span.between(self.span);
5803 let ty_second = if self.token == token::DotDot {
5804 // We need to report this error after `cfg` expansion for compatibility reasons
5805 self.bump(); // `..`, do not add it to expected tokens
5806 Some(P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID }))
5807 } else if has_for || self.token.can_begin_type() {
5808 Some(self.parse_ty()?)
5813 generics.where_clause = self.parse_where_clause()?;
5815 let (impl_items, attrs) = self.parse_impl_body()?;
5817 let item_kind = match ty_second {
5818 Some(ty_second) => {
5819 // impl Trait for Type
5821 self.span_err(missing_for_span, "missing `for` in a trait impl");
5824 let ty_first = ty_first.into_inner();
5825 let path = match ty_first.node {
5826 // This notably includes paths passed through `ty` macro fragments (#46438).
5827 TyKind::Path(None, path) => path,
5829 self.span_err(ty_first.span, "expected a trait, found type");
5830 ast::Path::from_ident(Ident::new(keywords::Invalid.name(), ty_first.span))
5833 let trait_ref = TraitRef { path, ref_id: ty_first.id };
5835 ItemKind::Impl(unsafety, polarity, defaultness,
5836 generics, Some(trait_ref), ty_second, impl_items)
5840 ItemKind::Impl(unsafety, polarity, defaultness,
5841 generics, None, ty_first, impl_items)
5845 Ok((keywords::Invalid.ident(), item_kind, Some(attrs)))
5848 fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
5849 if self.eat_keyword(keywords::For) {
5851 let params = self.parse_generic_params()?;
5853 // We rely on AST validation to rule out invalid cases: There must not be type
5854 // parameters, and the lifetime parameters must not have bounds.
5861 /// Parse struct Foo { ... }
5862 fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
5863 let class_name = self.parse_ident()?;
5865 let mut generics = self.parse_generics()?;
5867 // There is a special case worth noting here, as reported in issue #17904.
5868 // If we are parsing a tuple struct it is the case that the where clause
5869 // should follow the field list. Like so:
5871 // struct Foo<T>(T) where T: Copy;
5873 // If we are parsing a normal record-style struct it is the case
5874 // that the where clause comes before the body, and after the generics.
5875 // So if we look ahead and see a brace or a where-clause we begin
5876 // parsing a record style struct.
5878 // Otherwise if we look ahead and see a paren we parse a tuple-style
5881 let vdata = if self.token.is_keyword(keywords::Where) {
5882 generics.where_clause = self.parse_where_clause()?;
5883 if self.eat(&token::Semi) {
5884 // If we see a: `struct Foo<T> where T: Copy;` style decl.
5885 VariantData::Unit(ast::DUMMY_NODE_ID)
5887 // If we see: `struct Foo<T> where T: Copy { ... }`
5888 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
5890 // No `where` so: `struct Foo<T>;`
5891 } else if self.eat(&token::Semi) {
5892 VariantData::Unit(ast::DUMMY_NODE_ID)
5893 // Record-style struct definition
5894 } else if self.token == token::OpenDelim(token::Brace) {
5895 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
5896 // Tuple-style struct definition with optional where-clause.
5897 } else if self.token == token::OpenDelim(token::Paren) {
5898 let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID);
5899 generics.where_clause = self.parse_where_clause()?;
5900 self.expect(&token::Semi)?;
5903 let token_str = self.this_token_to_string();
5904 let mut err = self.fatal(&format!(
5905 "expected `where`, `{{`, `(`, or `;` after struct name, found `{}`",
5908 err.span_label(self.span, "expected `where`, `{`, `(`, or `;` after struct name");
5912 Ok((class_name, ItemKind::Struct(vdata, generics), None))
5915 /// Parse union Foo { ... }
5916 fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
5917 let class_name = self.parse_ident()?;
5919 let mut generics = self.parse_generics()?;
5921 let vdata = if self.token.is_keyword(keywords::Where) {
5922 generics.where_clause = self.parse_where_clause()?;
5923 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
5924 } else if self.token == token::OpenDelim(token::Brace) {
5925 VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
5927 let token_str = self.this_token_to_string();
5928 let mut err = self.fatal(&format!(
5929 "expected `where` or `{{` after union name, found `{}`", token_str));
5930 err.span_label(self.span, "expected `where` or `{` after union name");
5934 Ok((class_name, ItemKind::Union(vdata, generics), None))
5937 fn consume_block(&mut self, delim: token::DelimToken) {
5938 let mut brace_depth = 0;
5939 if !self.eat(&token::OpenDelim(delim)) {
5943 if self.eat(&token::OpenDelim(delim)) {
5945 } else if self.eat(&token::CloseDelim(delim)) {
5946 if brace_depth == 0 {
5952 } else if self.eat(&token::Eof) || self.eat(&token::CloseDelim(token::NoDelim)) {
5960 fn parse_record_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
5961 let mut fields = Vec::new();
5962 if self.eat(&token::OpenDelim(token::Brace)) {
5963 while self.token != token::CloseDelim(token::Brace) {
5964 let field = self.parse_struct_decl_field().map_err(|e| {
5965 self.recover_stmt();
5969 Ok(field) => fields.push(field),
5975 self.eat(&token::CloseDelim(token::Brace));
5977 let token_str = self.this_token_to_string();
5978 let mut err = self.fatal(&format!(
5979 "expected `where`, or `{{` after struct name, found `{}`", token_str));
5980 err.span_label(self.span, "expected `where`, or `{` after struct name");
5987 fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
5988 // This is the case where we find `struct Foo<T>(T) where T: Copy;`
5989 // Unit like structs are handled in parse_item_struct function
5990 let fields = self.parse_unspanned_seq(
5991 &token::OpenDelim(token::Paren),
5992 &token::CloseDelim(token::Paren),
5993 SeqSep::trailing_allowed(token::Comma),
5995 let attrs = p.parse_outer_attributes()?;
5997 let vis = p.parse_visibility(true)?;
5998 let ty = p.parse_ty()?;
6000 span: lo.to(ty.span),
6003 id: ast::DUMMY_NODE_ID,
6012 /// Parse a structure field declaration
6013 fn parse_single_struct_field(&mut self,
6016 attrs: Vec<Attribute> )
6017 -> PResult<'a, StructField> {
6018 let mut seen_comma: bool = false;
6019 let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
6020 if self.token == token::Comma {
6027 token::CloseDelim(token::Brace) => {}
6028 token::DocComment(_) => {
6029 let previous_span = self.prev_span;
6030 let mut err = self.span_fatal_err(self.span, Error::UselessDocComment);
6031 self.bump(); // consume the doc comment
6032 let comma_after_doc_seen = self.eat(&token::Comma);
6033 // `seen_comma` is always false, because we are inside doc block
6034 // condition is here to make code more readable
6035 if seen_comma == false && comma_after_doc_seen == true {
6038 if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
6041 if seen_comma == false {
6042 let sp = self.sess.source_map().next_point(previous_span);
6043 err.span_suggestion_with_applicability(
6045 "missing comma here",
6047 Applicability::MachineApplicable
6054 let sp = self.sess.source_map().next_point(self.prev_span);
6055 let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found `{}`",
6056 self.this_token_to_string()));
6057 if self.token.is_ident() {
6058 // This is likely another field; emit the diagnostic and keep going
6059 err.span_suggestion(sp, "try adding a comma", ",".into());
6069 /// Parse an element of a struct definition
6070 fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
6071 let attrs = self.parse_outer_attributes()?;
6073 let vis = self.parse_visibility(false)?;
6074 self.parse_single_struct_field(lo, vis, attrs)
6077 /// Parse `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `pub(self)` for `pub(in self)`
6078 /// and `pub(super)` for `pub(in super)`. If the following element can't be a tuple (i.e. it's
6079 /// a function definition, it's not a tuple struct field) and the contents within the parens
6080 /// isn't valid, emit a proper diagnostic.
6081 pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
6082 maybe_whole!(self, NtVis, |x| x);
6084 self.expected_tokens.push(TokenType::Keyword(keywords::Crate));
6085 if self.is_crate_vis() {
6086 self.bump(); // `crate`
6087 return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
6090 if !self.eat_keyword(keywords::Pub) {
6091 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
6092 // keyword to grab a span from for inherited visibility; an empty span at the
6093 // beginning of the current token would seem to be the "Schelling span".
6094 return Ok(respan(self.span.shrink_to_lo(), VisibilityKind::Inherited))
6096 let lo = self.prev_span;
6098 if self.check(&token::OpenDelim(token::Paren)) {
6099 // We don't `self.bump()` the `(` yet because this might be a struct definition where
6100 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
6101 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
6102 // by the following tokens.
6103 if self.look_ahead(1, |t| t.is_keyword(keywords::Crate)) {
6106 self.bump(); // `crate`
6107 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6109 lo.to(self.prev_span),
6110 VisibilityKind::Crate(CrateSugar::PubCrate),
6113 } else if self.look_ahead(1, |t| t.is_keyword(keywords::In)) {
6116 self.bump(); // `in`
6117 let path = self.parse_path(PathStyle::Mod)?; // `path`
6118 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6119 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6121 id: ast::DUMMY_NODE_ID,
6124 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
6125 self.look_ahead(1, |t| t.is_keyword(keywords::Super) ||
6126 t.is_keyword(keywords::SelfValue))
6128 // `pub(self)` or `pub(super)`
6130 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
6131 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6132 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6134 id: ast::DUMMY_NODE_ID,
6137 } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct
6138 // `pub(something) fn ...` or `struct X { pub(something) y: Z }`
6140 let msg = "incorrect visibility restriction";
6141 let suggestion = r##"some possible visibility restrictions are:
6142 `pub(crate)`: visible only on the current crate
6143 `pub(super)`: visible only in the current module's parent
6144 `pub(in path::to::module)`: visible only on the specified path"##;
6145 let path = self.parse_path(PathStyle::Mod)?;
6146 let sp = self.prev_span;
6147 let help_msg = format!("make this visible only to module `{}` with `in`", path);
6148 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6149 let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg);
6150 err.help(suggestion);
6151 err.span_suggestion_with_applicability(
6152 sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable
6154 err.emit(); // emit diagnostic, but continue with public visibility
6158 Ok(respan(lo, VisibilityKind::Public))
6161 /// Parse defaultness: `default` or nothing.
6162 fn parse_defaultness(&mut self) -> Defaultness {
6163 // `pub` is included for better error messages
6164 if self.check_keyword(keywords::Default) &&
6165 self.look_ahead(1, |t| t.is_keyword(keywords::Impl) ||
6166 t.is_keyword(keywords::Const) ||
6167 t.is_keyword(keywords::Fn) ||
6168 t.is_keyword(keywords::Unsafe) ||
6169 t.is_keyword(keywords::Extern) ||
6170 t.is_keyword(keywords::Type) ||
6171 t.is_keyword(keywords::Pub)) {
6172 self.bump(); // `default`
6173 Defaultness::Default
6179 /// Given a termination token, parse all of the items in a module
6180 fn parse_mod_items(&mut self, term: &token::Token, inner_lo: Span) -> PResult<'a, Mod> {
6181 let mut items = vec![];
6182 while let Some(item) = self.parse_item()? {
6186 if !self.eat(term) {
6187 let token_str = self.this_token_to_string();
6188 let mut err = self.fatal(&format!("expected item, found `{}`", token_str));
6189 if token_str == ";" {
6190 let msg = "consider removing this semicolon";
6191 err.span_suggestion_short_with_applicability(
6192 self.span, msg, "".to_string(), Applicability::MachineApplicable
6194 if !items.is_empty() { // Issue #51603
6195 let previous_item = &items[items.len()-1];
6196 let previous_item_kind_name = match previous_item.node {
6197 // say "braced struct" because tuple-structs and
6198 // braceless-empty-struct declarations do take a semicolon
6199 ItemKind::Struct(..) => Some("braced struct"),
6200 ItemKind::Enum(..) => Some("enum"),
6201 ItemKind::Trait(..) => Some("trait"),
6202 ItemKind::Union(..) => Some("union"),
6205 if let Some(name) = previous_item_kind_name {
6206 err.help(&format!("{} declarations are not followed by a semicolon",
6211 err.span_label(self.span, "expected item");
6216 let hi = if self.span.is_dummy() {
6223 inner: inner_lo.to(hi),
6228 fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
6229 let id = self.parse_ident()?;
6230 self.expect(&token::Colon)?;
6231 let ty = self.parse_ty()?;
6232 self.expect(&token::Eq)?;
6233 let e = self.parse_expr()?;
6234 self.expect(&token::Semi)?;
6235 let item = match m {
6236 Some(m) => ItemKind::Static(ty, m, e),
6237 None => ItemKind::Const(ty, e),
6239 Ok((id, item, None))
6242 /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
6243 fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
6244 let (in_cfg, outer_attrs) = {
6245 let mut strip_unconfigured = ::config::StripUnconfigured {
6247 should_test: false, // irrelevant
6248 features: None, // don't perform gated feature checking
6250 let outer_attrs = strip_unconfigured.process_cfg_attrs(outer_attrs.to_owned());
6251 (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), outer_attrs)
6254 let id_span = self.span;
6255 let id = self.parse_ident()?;
6256 if self.check(&token::Semi) {
6258 if in_cfg && self.recurse_into_file_modules {
6259 // This mod is in an external file. Let's go get it!
6260 let ModulePathSuccess { path, directory_ownership, warn } =
6261 self.submod_path(id, &outer_attrs, id_span)?;
6262 let (module, mut attrs) =
6263 self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
6265 let attr = Attribute {
6266 id: attr::mk_attr_id(),
6267 style: ast::AttrStyle::Outer,
6268 path: ast::Path::from_ident(Ident::from_str("warn_directory_ownership")),
6269 tokens: TokenStream::empty(),
6270 is_sugared_doc: false,
6271 span: syntax_pos::DUMMY_SP,
6273 attr::mark_known(&attr);
6276 Ok((id, module, Some(attrs)))
6278 let placeholder = ast::Mod { inner: syntax_pos::DUMMY_SP, items: Vec::new() };
6279 Ok((id, ItemKind::Mod(placeholder), None))
6282 let old_directory = self.directory.clone();
6283 self.push_directory(id, &outer_attrs);
6285 self.expect(&token::OpenDelim(token::Brace))?;
6286 let mod_inner_lo = self.span;
6287 let attrs = self.parse_inner_attributes()?;
6288 let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
6290 self.directory = old_directory;
6291 Ok((id, ItemKind::Mod(module), Some(attrs)))
6295 fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
6296 if let Some(path) = attr::first_attr_value_str_by_name(attrs, "path") {
6297 self.directory.path.to_mut().push(&path.as_str());
6298 self.directory.ownership = DirectoryOwnership::Owned { relative: None };
6300 self.directory.path.to_mut().push(&id.as_str());
6304 pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
6305 if let Some(s) = attr::first_attr_value_str_by_name(attrs, "path") {
6308 // On windows, the base path might have the form
6309 // `\\?\foo\bar` in which case it does not tolerate
6310 // mixed `/` and `\` separators, so canonicalize
6313 let s = s.replace("/", "\\");
6314 Some(dir_path.join(s))
6320 /// Returns either a path to a module, or .
6321 pub fn default_submod_path(
6323 relative: Option<ast::Ident>,
6325 source_map: &SourceMap) -> ModulePath
6327 // If we're in a foo.rs file instead of a mod.rs file,
6328 // we need to look for submodules in
6329 // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
6330 // `./<id>.rs` and `./<id>/mod.rs`.
6331 let relative_prefix_string;
6332 let relative_prefix = if let Some(ident) = relative {
6333 relative_prefix_string = format!("{}{}", ident.as_str(), path::MAIN_SEPARATOR);
6334 &relative_prefix_string
6339 let mod_name = id.to_string();
6340 let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
6341 let secondary_path_str = format!("{}{}{}mod.rs",
6342 relative_prefix, mod_name, path::MAIN_SEPARATOR);
6343 let default_path = dir_path.join(&default_path_str);
6344 let secondary_path = dir_path.join(&secondary_path_str);
6345 let default_exists = source_map.file_exists(&default_path);
6346 let secondary_exists = source_map.file_exists(&secondary_path);
6348 let result = match (default_exists, secondary_exists) {
6349 (true, false) => Ok(ModulePathSuccess {
6351 directory_ownership: DirectoryOwnership::Owned {
6356 (false, true) => Ok(ModulePathSuccess {
6357 path: secondary_path,
6358 directory_ownership: DirectoryOwnership::Owned {
6363 (false, false) => Err(Error::FileNotFoundForModule {
6364 mod_name: mod_name.clone(),
6365 default_path: default_path_str,
6366 secondary_path: secondary_path_str,
6367 dir_path: dir_path.display().to_string(),
6369 (true, true) => Err(Error::DuplicatePaths {
6370 mod_name: mod_name.clone(),
6371 default_path: default_path_str,
6372 secondary_path: secondary_path_str,
6378 path_exists: default_exists || secondary_exists,
6383 fn submod_path(&mut self,
6385 outer_attrs: &[Attribute],
6387 -> PResult<'a, ModulePathSuccess> {
6388 if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
6389 return Ok(ModulePathSuccess {
6390 directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
6391 // All `#[path]` files are treated as though they are a `mod.rs` file.
6392 // This means that `mod foo;` declarations inside `#[path]`-included
6393 // files are siblings,
6395 // Note that this will produce weirdness when a file named `foo.rs` is
6396 // `#[path]` included and contains a `mod foo;` declaration.
6397 // If you encounter this, it's your own darn fault :P
6398 Some(_) => DirectoryOwnership::Owned { relative: None },
6399 _ => DirectoryOwnership::UnownedViaMod(true),
6406 let relative = match self.directory.ownership {
6407 DirectoryOwnership::Owned { relative } => {
6408 // Push the usage onto the list of non-mod.rs mod uses.
6409 // This is used later for feature-gate error reporting.
6410 if let Some(cur_file_ident) = relative {
6412 .non_modrs_mods.borrow_mut()
6413 .push((cur_file_ident, id_sp));
6417 DirectoryOwnership::UnownedViaBlock |
6418 DirectoryOwnership::UnownedViaMod(_) => None,
6420 let paths = Parser::default_submod_path(
6421 id, relative, &self.directory.path, self.sess.source_map());
6423 match self.directory.ownership {
6424 DirectoryOwnership::Owned { .. } => {
6425 paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
6427 DirectoryOwnership::UnownedViaBlock => {
6429 "Cannot declare a non-inline module inside a block \
6430 unless it has a path attribute";
6431 let mut err = self.diagnostic().struct_span_err(id_sp, msg);
6432 if paths.path_exists {
6433 let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
6435 err.span_note(id_sp, &msg);
6439 DirectoryOwnership::UnownedViaMod(warn) => {
6441 if let Ok(result) = paths.result {
6442 return Ok(ModulePathSuccess { warn: true, ..result });
6445 let mut err = self.diagnostic().struct_span_err(id_sp,
6446 "cannot declare a new module at this location");
6447 if !id_sp.is_dummy() {
6448 let src_path = self.sess.source_map().span_to_filename(id_sp);
6449 if let FileName::Real(src_path) = src_path {
6450 if let Some(stem) = src_path.file_stem() {
6451 let mut dest_path = src_path.clone();
6452 dest_path.set_file_name(stem);
6453 dest_path.push("mod.rs");
6454 err.span_note(id_sp,
6455 &format!("maybe move this module `{}` to its own \
6456 directory via `{}`", src_path.display(),
6457 dest_path.display()));
6461 if paths.path_exists {
6462 err.span_note(id_sp,
6463 &format!("... or maybe `use` the module `{}` instead \
6464 of possibly redeclaring it",
6472 /// Read a module from a source file.
6473 fn eval_src_mod(&mut self,
6475 directory_ownership: DirectoryOwnership,
6478 -> PResult<'a, (ast::ItemKind, Vec<Attribute> )> {
6479 let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
6480 if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
6481 let mut err = String::from("circular modules: ");
6482 let len = included_mod_stack.len();
6483 for p in &included_mod_stack[i.. len] {
6484 err.push_str(&p.to_string_lossy());
6485 err.push_str(" -> ");
6487 err.push_str(&path.to_string_lossy());
6488 return Err(self.span_fatal(id_sp, &err[..]));
6490 included_mod_stack.push(path.clone());
6491 drop(included_mod_stack);
6494 new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
6495 p0.cfg_mods = self.cfg_mods;
6496 let mod_inner_lo = p0.span;
6497 let mod_attrs = p0.parse_inner_attributes()?;
6498 let m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
6499 self.sess.included_mod_stack.borrow_mut().pop();
6500 Ok((ast::ItemKind::Mod(m0), mod_attrs))
6503 /// Parse a function declaration from a foreign module
6504 fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6505 -> PResult<'a, ForeignItem> {
6506 self.expect_keyword(keywords::Fn)?;
6508 let (ident, mut generics) = self.parse_fn_header()?;
6509 let decl = self.parse_fn_decl(true)?;
6510 generics.where_clause = self.parse_where_clause()?;
6512 self.expect(&token::Semi)?;
6513 Ok(ast::ForeignItem {
6516 node: ForeignItemKind::Fn(decl, generics),
6517 id: ast::DUMMY_NODE_ID,
6523 /// Parse a static item from a foreign module.
6524 /// Assumes that the `static` keyword is already parsed.
6525 fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6526 -> PResult<'a, ForeignItem> {
6527 let mutbl = self.eat_keyword(keywords::Mut);
6528 let ident = self.parse_ident()?;
6529 self.expect(&token::Colon)?;
6530 let ty = self.parse_ty()?;
6532 self.expect(&token::Semi)?;
6536 node: ForeignItemKind::Static(ty, mutbl),
6537 id: ast::DUMMY_NODE_ID,
6543 /// Parse a type from a foreign module
6544 fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6545 -> PResult<'a, ForeignItem> {
6546 self.expect_keyword(keywords::Type)?;
6548 let ident = self.parse_ident()?;
6550 self.expect(&token::Semi)?;
6551 Ok(ast::ForeignItem {
6554 node: ForeignItemKind::Ty,
6555 id: ast::DUMMY_NODE_ID,
6561 fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
6562 let error_msg = "crate name using dashes are not valid in `extern crate` statements";
6563 let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
6565 let mut ident = self.parse_ident()?;
6566 let mut idents = vec![];
6567 let mut replacement = vec![];
6568 let mut fixed_crate_name = false;
6569 // Accept `extern crate name-like-this` for better diagnostics
6570 let dash = token::Token::BinOp(token::BinOpToken::Minus);
6571 if self.token == dash { // Do not include `-` as part of the expected tokens list
6572 while self.eat(&dash) {
6573 fixed_crate_name = true;
6574 replacement.push((self.prev_span, "_".to_string()));
6575 idents.push(self.parse_ident()?);
6578 if fixed_crate_name {
6579 let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
6580 let mut fixed_name = format!("{}", ident.name);
6581 for part in idents {
6582 fixed_name.push_str(&format!("_{}", part.name));
6584 ident = Ident::from_str(&fixed_name).with_span_pos(fixed_name_sp);
6586 let mut err = self.struct_span_err(fixed_name_sp, error_msg);
6587 err.span_label(fixed_name_sp, "dash-separated idents are not valid");
6588 err.multipart_suggestion(suggestion_msg, replacement);
6594 /// Parse extern crate links
6598 /// extern crate foo;
6599 /// extern crate bar as foo;
6600 fn parse_item_extern_crate(&mut self,
6602 visibility: Visibility,
6603 attrs: Vec<Attribute>)
6604 -> PResult<'a, P<Item>> {
6605 // Accept `extern crate name-like-this` for better diagnostics
6606 let orig_name = self.parse_crate_name_with_dashes()?;
6607 let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
6608 (rename, Some(orig_name.name))
6612 self.expect(&token::Semi)?;
6614 let span = lo.to(self.prev_span);
6615 Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
6618 /// Parse `extern` for foreign ABIs
6621 /// `extern` is expected to have been
6622 /// consumed before calling this method
6628 fn parse_item_foreign_mod(&mut self,
6630 opt_abi: Option<Abi>,
6631 visibility: Visibility,
6632 mut attrs: Vec<Attribute>)
6633 -> PResult<'a, P<Item>> {
6634 self.expect(&token::OpenDelim(token::Brace))?;
6636 let abi = opt_abi.unwrap_or(Abi::C);
6638 attrs.extend(self.parse_inner_attributes()?);
6640 let mut foreign_items = vec![];
6641 while let Some(item) = self.parse_foreign_item()? {
6642 foreign_items.push(item);
6644 self.expect(&token::CloseDelim(token::Brace))?;
6646 let prev_span = self.prev_span;
6647 let m = ast::ForeignMod {
6649 items: foreign_items
6651 let invalid = keywords::Invalid.ident();
6652 Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
6655 /// Parse type Foo = Bar;
6657 /// existential type Foo: Bar;
6659 /// return None without modifying the parser state
6660 fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
6661 // This parses the grammar:
6662 // Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
6663 if self.check_keyword(keywords::Type) ||
6664 self.check_keyword(keywords::Existential) &&
6665 self.look_ahead(1, |t| t.is_keyword(keywords::Type)) {
6666 let existential = self.eat_keyword(keywords::Existential);
6667 assert!(self.eat_keyword(keywords::Type));
6668 Some(self.parse_existential_or_alias(existential))
6674 /// Parse type alias or existential type
6675 fn parse_existential_or_alias(
6678 ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
6679 let ident = self.parse_ident()?;
6680 let mut tps = self.parse_generics()?;
6681 tps.where_clause = self.parse_where_clause()?;
6682 let alias = if existential {
6683 self.expect(&token::Colon)?;
6684 let bounds = self.parse_generic_bounds()?;
6685 AliasKind::Existential(bounds)
6687 self.expect(&token::Eq)?;
6688 let ty = self.parse_ty()?;
6691 self.expect(&token::Semi)?;
6692 Ok((ident, alias, tps))
6695 /// Parse the part of an "enum" decl following the '{'
6696 fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
6697 let mut variants = Vec::new();
6698 let mut all_nullary = true;
6699 let mut any_disr = None;
6700 while self.token != token::CloseDelim(token::Brace) {
6701 let variant_attrs = self.parse_outer_attributes()?;
6702 let vlo = self.span;
6705 let mut disr_expr = None;
6706 let ident = self.parse_ident()?;
6707 if self.check(&token::OpenDelim(token::Brace)) {
6708 // Parse a struct variant.
6709 all_nullary = false;
6710 struct_def = VariantData::Struct(self.parse_record_struct_body()?,
6711 ast::DUMMY_NODE_ID);
6712 } else if self.check(&token::OpenDelim(token::Paren)) {
6713 all_nullary = false;
6714 struct_def = VariantData::Tuple(self.parse_tuple_struct_body()?,
6715 ast::DUMMY_NODE_ID);
6716 } else if self.eat(&token::Eq) {
6717 disr_expr = Some(AnonConst {
6718 id: ast::DUMMY_NODE_ID,
6719 value: self.parse_expr()?,
6721 any_disr = disr_expr.as_ref().map(|c| c.value.span);
6722 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6724 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6727 let vr = ast::Variant_ {
6729 attrs: variant_attrs,
6733 variants.push(respan(vlo.to(self.prev_span), vr));
6735 if !self.eat(&token::Comma) { break; }
6737 self.expect(&token::CloseDelim(token::Brace))?;
6739 Some(disr_span) if !all_nullary =>
6740 self.span_err(disr_span,
6741 "discriminator values can only be used with a field-less enum"),
6745 Ok(ast::EnumDef { variants: variants })
6748 /// Parse an "enum" declaration
6749 fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
6750 let id = self.parse_ident()?;
6751 let mut generics = self.parse_generics()?;
6752 generics.where_clause = self.parse_where_clause()?;
6753 self.expect(&token::OpenDelim(token::Brace))?;
6755 let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
6756 self.recover_stmt();
6757 self.eat(&token::CloseDelim(token::Brace));
6760 Ok((id, ItemKind::Enum(enum_definition, generics), None))
6763 /// Parses a string as an ABI spec on an extern type or module. Consumes
6764 /// the `extern` keyword, if one is found.
6765 fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
6767 token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
6769 self.expect_no_suffix(sp, "ABI spec", suf);
6771 match abi::lookup(&s.as_str()) {
6772 Some(abi) => Ok(Some(abi)),
6774 let prev_span = self.prev_span;
6775 let mut err = struct_span_err!(
6776 self.sess.span_diagnostic,
6779 "invalid ABI: found `{}`",
6781 err.span_label(prev_span, "invalid ABI");
6782 err.help(&format!("valid ABIs: {}", abi::all_names().join(", ")));
6793 fn is_static_global(&mut self) -> bool {
6794 if self.check_keyword(keywords::Static) {
6795 // Check if this could be a closure
6796 !self.look_ahead(1, |token| {
6797 if token.is_keyword(keywords::Move) {
6801 token::BinOp(token::Or) | token::OrOr => true,
6812 attrs: Vec<Attribute>,
6813 macros_allowed: bool,
6814 attributes_allowed: bool,
6815 ) -> PResult<'a, Option<P<Item>>> {
6816 let (ret, tokens) = self.collect_tokens(|this| {
6817 this.parse_item_implementation(attrs, macros_allowed, attributes_allowed)
6820 // Once we've parsed an item and recorded the tokens we got while
6821 // parsing we may want to store `tokens` into the item we're about to
6822 // return. Note, though, that we specifically didn't capture tokens
6823 // related to outer attributes. The `tokens` field here may later be
6824 // used with procedural macros to convert this item back into a token
6825 // stream, but during expansion we may be removing attributes as we go
6828 // If we've got inner attributes then the `tokens` we've got above holds
6829 // these inner attributes. If an inner attribute is expanded we won't
6830 // actually remove it from the token stream, so we'll just keep yielding
6831 // it (bad!). To work around this case for now we just avoid recording
6832 // `tokens` if we detect any inner attributes. This should help keep
6833 // expansion correct, but we should fix this bug one day!
6836 if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
6837 i.tokens = Some(tokens);
6844 /// Parse one of the items allowed by the flags.
6845 /// NB: this function no longer parses the items inside an
6847 fn parse_item_implementation(
6849 attrs: Vec<Attribute>,
6850 macros_allowed: bool,
6851 attributes_allowed: bool,
6852 ) -> PResult<'a, Option<P<Item>>> {
6853 maybe_whole!(self, NtItem, |item| {
6854 let mut item = item.into_inner();
6855 let mut attrs = attrs;
6856 mem::swap(&mut item.attrs, &mut attrs);
6857 item.attrs.extend(attrs);
6863 let visibility = self.parse_visibility(false)?;
6865 if self.eat_keyword(keywords::Use) {
6867 let item_ = ItemKind::Use(P(self.parse_use_tree()?));
6868 self.expect(&token::Semi)?;
6870 let span = lo.to(self.prev_span);
6871 let item = self.mk_item(span, keywords::Invalid.ident(), item_, visibility, attrs);
6872 return Ok(Some(item));
6875 if self.check_keyword(keywords::Extern) && self.is_extern_non_path() {
6876 self.bump(); // `extern`
6877 if self.eat_keyword(keywords::Crate) {
6878 return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
6881 let opt_abi = self.parse_opt_abi()?;
6883 if self.eat_keyword(keywords::Fn) {
6884 // EXTERN FUNCTION ITEM
6885 let fn_span = self.prev_span;
6886 let abi = opt_abi.unwrap_or(Abi::C);
6887 let (ident, item_, extra_attrs) =
6888 self.parse_item_fn(Unsafety::Normal,
6890 respan(fn_span, Constness::NotConst),
6892 let prev_span = self.prev_span;
6893 let item = self.mk_item(lo.to(prev_span),
6897 maybe_append(attrs, extra_attrs));
6898 return Ok(Some(item));
6899 } else if self.check(&token::OpenDelim(token::Brace)) {
6900 return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
6906 if self.is_static_global() {
6909 let m = if self.eat_keyword(keywords::Mut) {
6912 Mutability::Immutable
6914 let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
6915 let prev_span = self.prev_span;
6916 let item = self.mk_item(lo.to(prev_span),
6920 maybe_append(attrs, extra_attrs));
6921 return Ok(Some(item));
6923 if self.eat_keyword(keywords::Const) {
6924 let const_span = self.prev_span;
6925 if self.check_keyword(keywords::Fn)
6926 || (self.check_keyword(keywords::Unsafe)
6927 && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
6928 // CONST FUNCTION ITEM
6929 let unsafety = self.parse_unsafety();
6931 let (ident, item_, extra_attrs) =
6932 self.parse_item_fn(unsafety,
6934 respan(const_span, Constness::Const),
6936 let prev_span = self.prev_span;
6937 let item = self.mk_item(lo.to(prev_span),
6941 maybe_append(attrs, extra_attrs));
6942 return Ok(Some(item));
6946 if self.eat_keyword(keywords::Mut) {
6947 let prev_span = self.prev_span;
6948 self.diagnostic().struct_span_err(prev_span, "const globals cannot be mutable")
6949 .help("did you mean to declare a static?")
6952 let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
6953 let prev_span = self.prev_span;
6954 let item = self.mk_item(lo.to(prev_span),
6958 maybe_append(attrs, extra_attrs));
6959 return Ok(Some(item));
6962 // `unsafe async fn` or `async fn`
6964 self.check_keyword(keywords::Unsafe) &&
6965 self.look_ahead(1, |t| t.is_keyword(keywords::Async))
6967 self.check_keyword(keywords::Async) &&
6968 self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
6971 // ASYNC FUNCTION ITEM
6972 let unsafety = self.parse_unsafety();
6973 self.expect_keyword(keywords::Async)?;
6974 self.expect_keyword(keywords::Fn)?;
6975 let fn_span = self.prev_span;
6976 let (ident, item_, extra_attrs) =
6977 self.parse_item_fn(unsafety,
6979 closure_id: ast::DUMMY_NODE_ID,
6980 return_impl_trait_id: ast::DUMMY_NODE_ID,
6982 respan(fn_span, Constness::NotConst),
6984 let prev_span = self.prev_span;
6985 let item = self.mk_item(lo.to(prev_span),
6989 maybe_append(attrs, extra_attrs));
6990 return Ok(Some(item));
6992 if self.check_keyword(keywords::Unsafe) &&
6993 (self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) ||
6994 self.look_ahead(1, |t| t.is_keyword(keywords::Auto)))
6996 // UNSAFE TRAIT ITEM
6997 self.bump(); // `unsafe`
6998 let is_auto = if self.eat_keyword(keywords::Trait) {
7001 self.expect_keyword(keywords::Auto)?;
7002 self.expect_keyword(keywords::Trait)?;
7005 let (ident, item_, extra_attrs) =
7006 self.parse_item_trait(is_auto, Unsafety::Unsafe)?;
7007 let prev_span = self.prev_span;
7008 let item = self.mk_item(lo.to(prev_span),
7012 maybe_append(attrs, extra_attrs));
7013 return Ok(Some(item));
7015 if self.check_keyword(keywords::Impl) ||
7016 self.check_keyword(keywords::Unsafe) &&
7017 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7018 self.check_keyword(keywords::Default) &&
7019 self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
7020 self.check_keyword(keywords::Default) &&
7021 self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) {
7023 let defaultness = self.parse_defaultness();
7024 let unsafety = self.parse_unsafety();
7025 self.expect_keyword(keywords::Impl)?;
7026 let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?;
7027 let span = lo.to(self.prev_span);
7028 return Ok(Some(self.mk_item(span, ident, item, visibility,
7029 maybe_append(attrs, extra_attrs))));
7031 if self.check_keyword(keywords::Fn) {
7034 let fn_span = self.prev_span;
7035 let (ident, item_, extra_attrs) =
7036 self.parse_item_fn(Unsafety::Normal,
7038 respan(fn_span, Constness::NotConst),
7040 let prev_span = self.prev_span;
7041 let item = self.mk_item(lo.to(prev_span),
7045 maybe_append(attrs, extra_attrs));
7046 return Ok(Some(item));
7048 if self.check_keyword(keywords::Unsafe)
7049 && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
7050 // UNSAFE FUNCTION ITEM
7051 self.bump(); // `unsafe`
7052 // `{` is also expected after `unsafe`, in case of error, include it in the diagnostic
7053 self.check(&token::OpenDelim(token::Brace));
7054 let abi = if self.eat_keyword(keywords::Extern) {
7055 self.parse_opt_abi()?.unwrap_or(Abi::C)
7059 self.expect_keyword(keywords::Fn)?;
7060 let fn_span = self.prev_span;
7061 let (ident, item_, extra_attrs) =
7062 self.parse_item_fn(Unsafety::Unsafe,
7064 respan(fn_span, Constness::NotConst),
7066 let prev_span = self.prev_span;
7067 let item = self.mk_item(lo.to(prev_span),
7071 maybe_append(attrs, extra_attrs));
7072 return Ok(Some(item));
7074 if self.eat_keyword(keywords::Mod) {
7076 let (ident, item_, extra_attrs) =
7077 self.parse_item_mod(&attrs[..])?;
7078 let prev_span = self.prev_span;
7079 let item = self.mk_item(lo.to(prev_span),
7083 maybe_append(attrs, extra_attrs));
7084 return Ok(Some(item));
7086 if let Some(type_) = self.eat_type() {
7087 let (ident, alias, generics) = type_?;
7089 let item_ = match alias {
7090 AliasKind::Weak(ty) => ItemKind::Ty(ty, generics),
7091 AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics),
7093 let prev_span = self.prev_span;
7094 let item = self.mk_item(lo.to(prev_span),
7099 return Ok(Some(item));
7101 if self.eat_keyword(keywords::Enum) {
7103 let (ident, item_, extra_attrs) = self.parse_item_enum()?;
7104 let prev_span = self.prev_span;
7105 let item = self.mk_item(lo.to(prev_span),
7109 maybe_append(attrs, extra_attrs));
7110 return Ok(Some(item));
7112 if self.check_keyword(keywords::Trait)
7113 || (self.check_keyword(keywords::Auto)
7114 && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
7116 let is_auto = if self.eat_keyword(keywords::Trait) {
7119 self.expect_keyword(keywords::Auto)?;
7120 self.expect_keyword(keywords::Trait)?;
7124 let (ident, item_, extra_attrs) =
7125 self.parse_item_trait(is_auto, Unsafety::Normal)?;
7126 let prev_span = self.prev_span;
7127 let item = self.mk_item(lo.to(prev_span),
7131 maybe_append(attrs, extra_attrs));
7132 return Ok(Some(item));
7134 if self.eat_keyword(keywords::Struct) {
7136 let (ident, item_, extra_attrs) = self.parse_item_struct()?;
7137 let prev_span = self.prev_span;
7138 let item = self.mk_item(lo.to(prev_span),
7142 maybe_append(attrs, extra_attrs));
7143 return Ok(Some(item));
7145 if self.is_union_item() {
7148 let (ident, item_, extra_attrs) = self.parse_item_union()?;
7149 let prev_span = self.prev_span;
7150 let item = self.mk_item(lo.to(prev_span),
7154 maybe_append(attrs, extra_attrs));
7155 return Ok(Some(item));
7157 if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, lo)? {
7158 return Ok(Some(macro_def));
7161 // Verify whether we have encountered a struct or method definition where the user forgot to
7162 // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
7163 if visibility.node.is_pub() &&
7164 self.check_ident() &&
7165 self.look_ahead(1, |t| *t != token::Not)
7167 // Space between `pub` keyword and the identifier
7170 // ^^^ `sp` points here
7171 let sp = self.prev_span.between(self.span);
7172 let full_sp = self.prev_span.to(self.span);
7173 let ident_sp = self.span;
7174 if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
7175 // possible public struct definition where `struct` was forgotten
7176 let ident = self.parse_ident().unwrap();
7177 let msg = format!("add `struct` here to parse `{}` as a public struct",
7179 let mut err = self.diagnostic()
7180 .struct_span_err(sp, "missing `struct` for struct definition");
7181 err.span_suggestion_short_with_applicability(
7182 sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
7185 } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
7186 let ident = self.parse_ident().unwrap();
7187 self.consume_block(token::Paren);
7188 let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) ||
7189 self.check(&token::OpenDelim(token::Brace))
7191 ("fn", "method", false)
7192 } else if self.check(&token::Colon) {
7196 ("fn` or `struct", "method or struct", true)
7199 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7200 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7202 let suggestion = format!("add `{}` here to parse `{}` as a public {}",
7206 err.span_suggestion_short_with_applicability(
7207 sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
7210 if let Ok(snippet) = self.sess.source_map().span_to_snippet(ident_sp) {
7211 err.span_suggestion_with_applicability(
7213 "if you meant to call a macro, try",
7214 format!("{}!", snippet),
7215 // this is the `ambiguous` conditional branch
7216 Applicability::MaybeIncorrect
7219 err.help("if you meant to call a macro, remove the `pub` \
7220 and add a trailing `!` after the identifier");
7226 self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, visibility)
7229 /// Parse a foreign item.
7230 crate fn parse_foreign_item(&mut self) -> PResult<'a, Option<ForeignItem>> {
7231 maybe_whole!(self, NtForeignItem, |ni| Some(ni));
7233 let attrs = self.parse_outer_attributes()?;
7235 let visibility = self.parse_visibility(false)?;
7237 // FOREIGN STATIC ITEM
7238 // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
7239 if self.check_keyword(keywords::Static) || self.token.is_keyword(keywords::Const) {
7240 if self.token.is_keyword(keywords::Const) {
7242 .struct_span_err(self.span, "extern items cannot be `const`")
7243 .span_suggestion_with_applicability(
7245 "try using a static value",
7246 "static".to_owned(),
7247 Applicability::MachineApplicable
7250 self.bump(); // `static` or `const`
7251 return Ok(Some(self.parse_item_foreign_static(visibility, lo, attrs)?));
7253 // FOREIGN FUNCTION ITEM
7254 if self.check_keyword(keywords::Fn) {
7255 return Ok(Some(self.parse_item_foreign_fn(visibility, lo, attrs)?));
7257 // FOREIGN TYPE ITEM
7258 if self.check_keyword(keywords::Type) {
7259 return Ok(Some(self.parse_item_foreign_type(visibility, lo, attrs)?));
7262 match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
7266 ident: keywords::Invalid.ident(),
7267 span: lo.to(self.prev_span),
7268 id: ast::DUMMY_NODE_ID,
7271 node: ForeignItemKind::Macro(mac),
7276 if !attrs.is_empty() {
7277 self.expected_item_err(&attrs);
7285 /// This is the fall-through for parsing items.
7286 fn parse_macro_use_or_failure(
7288 attrs: Vec<Attribute> ,
7289 macros_allowed: bool,
7290 attributes_allowed: bool,
7292 visibility: Visibility
7293 ) -> PResult<'a, Option<P<Item>>> {
7294 if macros_allowed && self.token.is_path_start() {
7295 // MACRO INVOCATION ITEM
7297 let prev_span = self.prev_span;
7298 self.complain_if_pub_macro(&visibility.node, prev_span);
7300 let mac_lo = self.span;
7303 let pth = self.parse_path(PathStyle::Mod)?;
7304 self.expect(&token::Not)?;
7306 // a 'special' identifier (like what `macro_rules!` uses)
7307 // is optional. We should eventually unify invoc syntax
7309 let id = if self.token.is_ident() {
7312 keywords::Invalid.ident() // no special identifier
7314 // eat a matched-delimiter token tree:
7315 let (delim, tts) = self.expect_delimited_token_tree()?;
7316 if delim != MacDelimiter::Brace {
7317 if !self.eat(&token::Semi) {
7318 self.span_err(self.prev_span,
7319 "macros that expand to items must either \
7320 be surrounded with braces or followed by \
7325 let hi = self.prev_span;
7326 let mac = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim });
7327 let item = self.mk_item(lo.to(hi), id, ItemKind::Mac(mac), visibility, attrs);
7328 return Ok(Some(item));
7331 // FAILURE TO PARSE ITEM
7332 match visibility.node {
7333 VisibilityKind::Inherited => {}
7335 return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
7339 if !attributes_allowed && !attrs.is_empty() {
7340 self.expected_item_err(&attrs);
7345 /// Parse a macro invocation inside a `trait`, `impl` or `extern` block
7346 fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
7347 at_end: &mut bool) -> PResult<'a, Option<Mac>>
7349 if self.token.is_path_start() && !self.is_extern_non_path() {
7350 let prev_span = self.prev_span;
7352 let pth = self.parse_path(PathStyle::Mod)?;
7354 if pth.segments.len() == 1 {
7355 if !self.eat(&token::Not) {
7356 return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
7359 self.expect(&token::Not)?;
7362 if let Some(vis) = vis {
7363 self.complain_if_pub_macro(&vis.node, prev_span);
7368 // eat a matched-delimiter token tree:
7369 let (delim, tts) = self.expect_delimited_token_tree()?;
7370 if delim != MacDelimiter::Brace {
7371 self.expect(&token::Semi)?
7374 Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim })))
7380 fn collect_tokens<F, R>(&mut self, f: F) -> PResult<'a, (R, TokenStream)>
7381 where F: FnOnce(&mut Self) -> PResult<'a, R>
7383 // Record all tokens we parse when parsing this item.
7384 let mut tokens = Vec::new();
7385 let prev_collecting = match self.token_cursor.frame.last_token {
7386 LastToken::Collecting(ref mut list) => {
7387 Some(mem::replace(list, Vec::new()))
7389 LastToken::Was(ref mut last) => {
7390 tokens.extend(last.take());
7394 self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
7395 let prev = self.token_cursor.stack.len();
7397 let last_token = if self.token_cursor.stack.len() == prev {
7398 &mut self.token_cursor.frame.last_token
7400 &mut self.token_cursor.stack[prev].last_token
7403 // Pull our the toekns that we've collected from the call to `f` above
7404 let mut collected_tokens = match *last_token {
7405 LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()),
7406 LastToken::Was(_) => panic!("our vector went away?"),
7409 // If we're not at EOF our current token wasn't actually consumed by
7410 // `f`, but it'll still be in our list that we pulled out. In that case
7412 let extra_token = if self.token != token::Eof {
7413 collected_tokens.pop()
7418 // If we were previously collecting tokens, then this was a recursive
7419 // call. In that case we need to record all the tokens we collected in
7420 // our parent list as well. To do that we push a clone of our stream
7421 // onto the previous list.
7422 let stream = collected_tokens.into_iter().collect::<TokenStream>();
7423 match prev_collecting {
7425 list.push(stream.clone());
7426 list.extend(extra_token);
7427 *last_token = LastToken::Collecting(list);
7430 *last_token = LastToken::Was(extra_token);
7437 pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
7438 let attrs = self.parse_outer_attributes()?;
7439 self.parse_item_(attrs, true, false)
7443 fn is_import_coupler(&mut self) -> bool {
7444 self.check(&token::ModSep) &&
7445 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
7446 *t == token::BinOp(token::Star))
7451 /// USE_TREE = [`::`] `*` |
7452 /// [`::`] `{` USE_TREE_LIST `}` |
7454 /// PATH `::` `{` USE_TREE_LIST `}` |
7455 /// PATH [`as` IDENT]
7456 fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
7459 let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
7460 let kind = if self.check(&token::OpenDelim(token::Brace)) ||
7461 self.check(&token::BinOp(token::Star)) ||
7462 self.is_import_coupler() {
7463 // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
7464 if self.eat(&token::ModSep) {
7465 prefix.segments.push(PathSegment::crate_root(lo.shrink_to_lo()));
7468 if self.eat(&token::BinOp(token::Star)) {
7471 UseTreeKind::Nested(self.parse_use_tree_list()?)
7474 // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
7475 prefix = self.parse_path(PathStyle::Mod)?;
7477 if self.eat(&token::ModSep) {
7478 if self.eat(&token::BinOp(token::Star)) {
7481 UseTreeKind::Nested(self.parse_use_tree_list()?)
7484 UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID)
7488 Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
7491 /// Parse UseTreeKind::Nested(list)
7493 /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
7494 fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
7495 self.parse_unspanned_seq(&token::OpenDelim(token::Brace),
7496 &token::CloseDelim(token::Brace),
7497 SeqSep::trailing_allowed(token::Comma), |this| {
7498 Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID))
7502 fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
7503 if self.eat_keyword(keywords::As) {
7505 token::Ident(ident, false) if ident.name == keywords::Underscore.name() => {
7507 Ok(Some(ident.gensym()))
7509 _ => self.parse_ident().map(Some),
7516 /// Parses a source module as a crate. This is the main
7517 /// entry point for the parser.
7518 pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
7521 attrs: self.parse_inner_attributes()?,
7522 module: self.parse_mod_items(&token::Eof, lo)?,
7523 span: lo.to(self.span),
7527 pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
7528 let ret = match self.token {
7529 token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf),
7530 token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf),
7537 pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
7538 match self.parse_optional_str() {
7539 Some((s, style, suf)) => {
7540 let sp = self.prev_span;
7541 self.expect_no_suffix(sp, "string literal", suf);
7545 let msg = "expected string literal";
7546 let mut err = self.fatal(msg);
7547 err.span_label(self.span, msg);