1 // ignore-tidy-filelength
3 use crate::ast::{AngleBracketedArgs, AsyncArgument, ParenthesizedArgs, AttrStyle, BareFnTy};
4 use crate::ast::{GenericBound, TraitBoundModifier};
5 use crate::ast::Unsafety;
6 use crate::ast::{Mod, AnonConst, Arg, ArgSource, Arm, Guard, Attribute, BindingMode, TraitItemKind};
8 use crate::ast::{BlockCheckMode, CaptureBy, Movability};
9 use crate::ast::{Constness, Crate};
10 use crate::ast::Defaultness;
11 use crate::ast::EnumDef;
12 use crate::ast::{Expr, ExprKind, RangeLimits};
13 use crate::ast::{Field, FnDecl, FnHeader};
14 use crate::ast::{ForeignItem, ForeignItemKind, FunctionRetTy};
15 use crate::ast::{GenericParam, GenericParamKind};
16 use crate::ast::GenericArg;
17 use crate::ast::{Ident, ImplItem, IsAsync, IsAuto, Item, ItemKind};
18 use crate::ast::{Label, Lifetime};
19 use crate::ast::{Local, LocalSource};
20 use crate::ast::MacStmtStyle;
21 use crate::ast::{Mac, Mac_, MacDelimiter};
22 use crate::ast::{MutTy, Mutability};
23 use crate::ast::{Pat, PatKind, PathSegment};
24 use crate::ast::{PolyTraitRef, QSelf};
25 use crate::ast::{Stmt, StmtKind};
26 use crate::ast::{VariantData, StructField};
27 use crate::ast::StrStyle;
28 use crate::ast::SelfKind;
29 use crate::ast::{TraitItem, TraitRef, TraitObjectSyntax};
30 use crate::ast::{Ty, TyKind, TypeBinding, GenericBounds};
31 use crate::ast::{Visibility, VisibilityKind, WhereClause, CrateSugar};
32 use crate::ast::{UseTree, UseTreeKind};
33 use crate::ast::{BinOpKind, UnOp};
34 use crate::ast::{RangeEnd, RangeSyntax};
35 use crate::{ast, attr};
36 use crate::ext::base::DummyResult;
37 use crate::source_map::{self, SourceMap, Spanned, respan};
38 use crate::parse::{SeqSep, classify, literal, token};
39 use crate::parse::lexer::{TokenAndSpan, UnmatchedBrace};
40 use crate::parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
41 use crate::parse::token::DelimToken;
42 use crate::parse::{new_sub_parser_from_file, ParseSess, Directory, DirectoryOwnership};
43 use crate::util::parser::{AssocOp, Fixity};
44 use crate::print::pprust;
46 use crate::parse::PResult;
48 use crate::tokenstream::{self, DelimSpan, TokenTree, TokenStream, TreeAndJoint};
49 use crate::symbol::{kw, sym, Symbol};
50 use crate::parse::diagnostics::Error;
52 use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
53 use rustc_target::spec::abi::{self, Abi};
54 use syntax_pos::{Span, BytePos, DUMMY_SP, FileName, hygiene::CompilerDesugaringKind};
60 use std::path::{self, Path, PathBuf};
64 /// Whether the type alias or associated type is a concrete type or an existential type
66 /// Just a new name for the same type
68 /// Only trait impls of the type will be usable, not the actual type itself
69 Existential(GenericBounds),
73 struct Restrictions: u8 {
74 const STMT_EXPR = 1 << 0;
75 const NO_STRUCT_LITERAL = 1 << 1;
79 type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>);
81 /// Specifies how to parse a path.
82 #[derive(Copy, Clone, PartialEq)]
84 /// In some contexts, notably in expressions, paths with generic arguments are ambiguous
85 /// with something else. For example, in expressions `segment < ....` can be interpreted
86 /// as a comparison and `segment ( ....` can be interpreted as a function call.
87 /// In all such contexts the non-path interpretation is preferred by default for practical
88 /// reasons, but the path interpretation can be forced by the disambiguator `::`, e.g.
89 /// `x<y>` - comparisons, `x::<y>` - unambiguously a path.
91 /// In other contexts, notably in types, no ambiguity exists and paths can be written
92 /// without the disambiguator, e.g., `x<y>` - unambiguously a path.
93 /// Paths with disambiguators are still accepted, `x::<Y>` - unambiguously a path too.
95 /// A path with generic arguments disallowed, e.g., `foo::bar::Baz`, used in imports,
96 /// visibilities or attributes.
97 /// Technically, this variant is unnecessary and e.g., `Expr` can be used instead
98 /// (paths in "mod" contexts have to be checked later for absence of generic arguments
99 /// anyway, due to macros), but it is used to avoid weird suggestions about expected
100 /// tokens when something goes wrong.
104 #[derive(Clone, Copy, PartialEq, Debug)]
105 crate enum SemiColonMode {
111 #[derive(Clone, Copy, PartialEq, Debug)]
112 crate enum BlockMode {
117 /// Possibly accepts an `token::Interpolated` expression (a pre-parsed expression
118 /// dropped into the token stream, which happens while parsing the result of
119 /// macro expansion). Placement of these is not as complex as I feared it would
120 /// be. The important thing is to make sure that lookahead doesn't balk at
121 /// `token::Interpolated` tokens.
122 macro_rules! maybe_whole_expr {
124 if let token::Interpolated(nt) = &$p.token {
126 token::NtExpr(e) | token::NtLiteral(e) => {
131 token::NtPath(path) => {
132 let path = path.clone();
134 return Ok($p.mk_expr($p.span, ExprKind::Path(None, path), ThinVec::new()));
136 token::NtBlock(block) => {
137 let block = block.clone();
139 return Ok($p.mk_expr($p.span, ExprKind::Block(block, None), ThinVec::new()));
147 /// As maybe_whole_expr, but for things other than expressions
148 macro_rules! maybe_whole {
149 ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
150 if let token::Interpolated(nt) = &$p.token {
151 if let token::$constructor(x) = &**nt {
160 /// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`.
161 macro_rules! maybe_recover_from_interpolated_ty_qpath {
162 ($self: expr, $allow_qpath_recovery: expr) => {
163 if $allow_qpath_recovery && $self.look_ahead(1, |t| t == &token::ModSep) {
164 if let token::Interpolated(nt) = &$self.token {
165 if let token::NtTy(ty) = &**nt {
168 return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_span, ty);
175 fn maybe_append(mut lhs: Vec<Attribute>, mut rhs: Option<Vec<Attribute>>) -> Vec<Attribute> {
176 if let Some(ref mut rhs) = rhs {
182 #[derive(Debug, Clone, Copy, PartialEq)]
194 /* ident is handled by common.rs */
197 pub struct Parser<'a> {
198 pub sess: &'a ParseSess,
199 /// the current token:
200 pub token: token::Token,
201 /// the span of the current token:
203 /// the span of the previous token:
204 meta_var_span: Option<Span>,
206 /// the previous token kind
207 prev_token_kind: PrevTokenKind,
208 restrictions: Restrictions,
209 /// Used to determine the path to externally loaded source files
210 crate directory: Directory<'a>,
211 /// Whether to parse sub-modules in other files.
212 pub recurse_into_file_modules: bool,
213 /// Name of the root module this parser originated from. If `None`, then the
214 /// name is not known. This does not change while the parser is descending
215 /// into modules, and sub-parsers have new values for this name.
216 pub root_module_name: Option<String>,
217 crate expected_tokens: Vec<TokenType>,
218 crate token_cursor: TokenCursor,
219 desugar_doc_comments: bool,
220 /// Whether we should configure out of line modules as we parse.
222 /// This field is used to keep track of how many left angle brackets we have seen. This is
223 /// required in order to detect extra leading left angle brackets (`<` characters) and error
226 /// See the comments in the `parse_path_segment` function for more details.
227 crate unmatched_angle_bracket_count: u32,
228 crate max_angle_bracket_count: u32,
229 /// List of all unclosed delimiters found by the lexer. If an entry is used for error recovery
230 /// it gets removed from here. Every entry left at the end gets emitted as an independent
232 crate unclosed_delims: Vec<UnmatchedBrace>,
233 crate last_unexpected_token_span: Option<Span>,
234 /// If present, this `Parser` is not parsing Rust code but rather a macro call.
235 crate subparser_name: Option<&'static str>,
238 impl<'a> Drop for Parser<'a> {
240 let diag = self.diagnostic();
241 emit_unclosed_delims(&mut self.unclosed_delims, diag);
246 crate struct TokenCursor {
247 crate frame: TokenCursorFrame,
248 crate stack: Vec<TokenCursorFrame>,
252 crate struct TokenCursorFrame {
253 crate delim: token::DelimToken,
254 crate span: DelimSpan,
255 crate open_delim: bool,
256 crate tree_cursor: tokenstream::Cursor,
257 crate close_delim: bool,
258 crate last_token: LastToken,
261 /// This is used in `TokenCursorFrame` above to track tokens that are consumed
262 /// by the parser, and then that's transitively used to record the tokens that
263 /// each parse AST item is created with.
265 /// Right now this has two states, either collecting tokens or not collecting
266 /// tokens. If we're collecting tokens we just save everything off into a local
267 /// `Vec`. This should eventually though likely save tokens from the original
268 /// token stream and just use slicing of token streams to avoid creation of a
269 /// whole new vector.
271 /// The second state is where we're passively not recording tokens, but the last
272 /// token is still tracked for when we want to start recording tokens. This
273 /// "last token" means that when we start recording tokens we'll want to ensure
274 /// that this, the first token, is included in the output.
276 /// You can find some more example usage of this in the `collect_tokens` method
279 crate enum LastToken {
280 Collecting(Vec<TreeAndJoint>),
281 Was(Option<TreeAndJoint>),
284 impl TokenCursorFrame {
285 fn new(sp: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
289 open_delim: delim == token::NoDelim,
290 tree_cursor: tts.clone().into_trees(),
291 close_delim: delim == token::NoDelim,
292 last_token: LastToken::Was(None),
298 fn next(&mut self) -> TokenAndSpan {
300 let tree = if !self.frame.open_delim {
301 self.frame.open_delim = true;
302 TokenTree::open_tt(self.frame.span.open, self.frame.delim)
303 } else if let Some(tree) = self.frame.tree_cursor.next() {
305 } else if !self.frame.close_delim {
306 self.frame.close_delim = true;
307 TokenTree::close_tt(self.frame.span.close, self.frame.delim)
308 } else if let Some(frame) = self.stack.pop() {
312 return TokenAndSpan { tok: token::Eof, sp: DUMMY_SP }
315 match self.frame.last_token {
316 LastToken::Collecting(ref mut v) => v.push(tree.clone().into()),
317 LastToken::Was(ref mut t) => *t = Some(tree.clone().into()),
321 TokenTree::Token(sp, tok) => return TokenAndSpan { tok: tok, sp: sp },
322 TokenTree::Delimited(sp, delim, tts) => {
323 let frame = TokenCursorFrame::new(sp, delim, &tts);
324 self.stack.push(mem::replace(&mut self.frame, frame));
330 fn next_desugared(&mut self) -> TokenAndSpan {
331 let (sp, name) = match self.next() {
332 TokenAndSpan { sp, tok: token::DocComment(name) } => (sp, name),
336 let stripped = strip_doc_comment_decoration(&name.as_str());
338 // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
339 // required to wrap the text.
340 let mut num_of_hashes = 0;
342 for ch in stripped.chars() {
345 '#' if count > 0 => count + 1,
348 num_of_hashes = cmp::max(num_of_hashes, count);
351 let delim_span = DelimSpan::from_single(sp);
352 let body = TokenTree::Delimited(
356 TokenTree::Token(sp, token::Ident(ast::Ident::with_empty_ctxt(sym::doc), false)),
357 TokenTree::Token(sp, token::Eq),
358 TokenTree::Token(sp, token::Token::lit(
359 token::StrRaw(num_of_hashes), Symbol::intern(&stripped), None
362 .iter().cloned().collect::<TokenStream>().into(),
365 self.stack.push(mem::replace(&mut self.frame, TokenCursorFrame::new(
368 &if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
369 [TokenTree::Token(sp, token::Pound), TokenTree::Token(sp, token::Not), body]
370 .iter().cloned().collect::<TokenStream>().into()
372 [TokenTree::Token(sp, token::Pound), body]
373 .iter().cloned().collect::<TokenStream>().into()
381 #[derive(Clone, PartialEq)]
382 crate enum TokenType {
394 crate fn to_string(&self) -> String {
396 TokenType::Token(ref t) => format!("`{}`", pprust::token_to_string(t)),
397 TokenType::Keyword(kw) => format!("`{}`", kw),
398 TokenType::Operator => "an operator".to_string(),
399 TokenType::Lifetime => "lifetime".to_string(),
400 TokenType::Ident => "identifier".to_string(),
401 TokenType::Path => "path".to_string(),
402 TokenType::Type => "type".to_string(),
403 TokenType::Const => "const".to_string(),
408 /// Returns `true` if `IDENT t` can start a type -- `IDENT::a::b`, `IDENT<u8, u8>`,
409 /// `IDENT<<u8 as Trait>::AssocTy>`.
411 /// Types can also be of the form `IDENT(u8, u8) -> u8`, however this assumes
412 /// that `IDENT` is not the ident of a fn trait.
413 fn can_continue_type_after_non_fn_ident(t: &token::Token) -> bool {
414 t == &token::ModSep || t == &token::Lt ||
415 t == &token::BinOp(token::Shl)
418 /// Information about the path to a module.
419 pub struct ModulePath {
422 pub result: Result<ModulePathSuccess, Error>,
425 pub struct ModulePathSuccess {
427 pub directory_ownership: DirectoryOwnership,
434 AttributesParsed(ThinVec<Attribute>),
435 AlreadyParsed(P<Expr>),
438 impl From<Option<ThinVec<Attribute>>> for LhsExpr {
439 fn from(o: Option<ThinVec<Attribute>>) -> Self {
440 if let Some(attrs) = o {
441 LhsExpr::AttributesParsed(attrs)
443 LhsExpr::NotYetParsed
448 impl From<P<Expr>> for LhsExpr {
449 fn from(expr: P<Expr>) -> Self {
450 LhsExpr::AlreadyParsed(expr)
454 /// Creates a placeholder argument.
455 fn dummy_arg(span: Span) -> Arg {
456 let ident = Ident::new(kw::Invalid, span);
458 id: ast::DUMMY_NODE_ID,
459 node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), ident, None),
465 id: ast::DUMMY_NODE_ID
467 Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID, source: ast::ArgSource::Normal }
470 #[derive(Copy, Clone, Debug)]
471 crate enum TokenExpectType {
476 impl<'a> Parser<'a> {
480 directory: Option<Directory<'a>>,
481 recurse_into_file_modules: bool,
482 desugar_doc_comments: bool,
483 subparser_name: Option<&'static str>,
485 let mut parser = Parser {
487 token: token::Whitespace,
491 prev_token_kind: PrevTokenKind::Other,
492 restrictions: Restrictions::empty(),
493 recurse_into_file_modules,
494 directory: Directory {
495 path: Cow::from(PathBuf::new()),
496 ownership: DirectoryOwnership::Owned { relative: None }
498 root_module_name: None,
499 expected_tokens: Vec::new(),
500 token_cursor: TokenCursor {
501 frame: TokenCursorFrame::new(
508 desugar_doc_comments,
510 unmatched_angle_bracket_count: 0,
511 max_angle_bracket_count: 0,
512 unclosed_delims: Vec::new(),
513 last_unexpected_token_span: None,
517 let tok = parser.next_tok();
518 parser.token = tok.tok;
519 parser.span = tok.sp;
521 if let Some(directory) = directory {
522 parser.directory = directory;
523 } else if !parser.span.is_dummy() {
524 if let FileName::Real(mut path) = sess.source_map().span_to_unmapped_path(parser.span) {
526 parser.directory.path = Cow::from(path);
530 parser.process_potential_macro_variable();
534 fn next_tok(&mut self) -> TokenAndSpan {
535 let mut next = if self.desugar_doc_comments {
536 self.token_cursor.next_desugared()
538 self.token_cursor.next()
540 if next.sp.is_dummy() {
541 // Tweak the location for better diagnostics, but keep syntactic context intact.
542 next.sp = self.prev_span.with_ctxt(next.sp.ctxt());
547 /// Converts the current token to a string using `self`'s reader.
548 pub fn this_token_to_string(&self) -> String {
549 pprust::token_to_string(&self.token)
552 crate fn token_descr(&self) -> Option<&'static str> {
553 Some(match &self.token {
554 t if t.is_special_ident() => "reserved identifier",
555 t if t.is_used_keyword() => "keyword",
556 t if t.is_unused_keyword() => "reserved keyword",
557 token::DocComment(..) => "doc comment",
562 crate fn this_token_descr(&self) -> String {
563 if let Some(prefix) = self.token_descr() {
564 format!("{} `{}`", prefix, self.this_token_to_string())
566 format!("`{}`", self.this_token_to_string())
570 crate fn unexpected<T>(&mut self) -> PResult<'a, T> {
571 match self.expect_one_of(&[], &[]) {
573 Ok(_) => unreachable!(),
577 /// Expects and consumes the token `t`. Signals an error if the next token is not `t`.
578 pub fn expect(&mut self, t: &token::Token) -> PResult<'a, bool /* recovered */> {
579 if self.expected_tokens.is_empty() {
580 if self.token == *t {
584 self.unexpected_try_recover(t)
587 self.expect_one_of(slice::from_ref(t), &[])
591 /// Expect next token to be edible or inedible token. If edible,
592 /// then consume it; if inedible, then return without consuming
593 /// anything. Signal a fatal error if next token is unexpected.
594 pub fn expect_one_of(
596 edible: &[token::Token],
597 inedible: &[token::Token],
598 ) -> PResult<'a, bool /* recovered */> {
599 if edible.contains(&self.token) {
602 } else if inedible.contains(&self.token) {
603 // leave it in the input
605 } else if self.last_unexpected_token_span == Some(self.span) {
608 self.expected_one_of_not_found(edible, inedible)
612 /// Returns the span of expr, if it was not interpolated or the span of the interpolated token.
613 fn interpolated_or_expr_span(
615 expr: PResult<'a, P<Expr>>,
616 ) -> PResult<'a, (Span, P<Expr>)> {
618 if self.prev_token_kind == PrevTokenKind::Interpolated {
626 pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
627 self.parse_ident_common(true)
630 fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
632 token::Ident(ident, _) => {
633 if self.token.is_reserved_ident() {
634 let mut err = self.expected_ident_found();
641 let span = self.span;
643 Ok(Ident::new(ident.name, span))
646 Err(if self.prev_token_kind == PrevTokenKind::DocComment {
647 self.span_fatal_err(self.prev_span, Error::UselessDocComment)
649 self.expected_ident_found()
655 /// Checks if the next token is `tok`, and returns `true` if so.
657 /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
659 crate fn check(&mut self, tok: &token::Token) -> bool {
660 let is_present = self.token == *tok;
661 if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
665 /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
666 pub fn eat(&mut self, tok: &token::Token) -> bool {
667 let is_present = self.check(tok);
668 if is_present { self.bump() }
672 fn check_keyword(&mut self, kw: Symbol) -> bool {
673 self.expected_tokens.push(TokenType::Keyword(kw));
674 self.token.is_keyword(kw)
677 /// If the next token is the given keyword, eats it and returns
678 /// `true`. Otherwise, returns `false`.
679 pub fn eat_keyword(&mut self, kw: Symbol) -> bool {
680 if self.check_keyword(kw) {
688 fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
689 if self.token.is_keyword(kw) {
697 /// If the given word is not a keyword, signals an error.
698 /// If the next token is not the given word, signals an error.
699 /// Otherwise, eats it.
700 fn expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()> {
701 if !self.eat_keyword(kw) {
708 crate fn check_ident(&mut self) -> bool {
709 if self.token.is_ident() {
712 self.expected_tokens.push(TokenType::Ident);
717 fn check_path(&mut self) -> bool {
718 if self.token.is_path_start() {
721 self.expected_tokens.push(TokenType::Path);
726 fn check_type(&mut self) -> bool {
727 if self.token.can_begin_type() {
730 self.expected_tokens.push(TokenType::Type);
735 fn check_const_arg(&mut self) -> bool {
736 if self.token.can_begin_const_arg() {
739 self.expected_tokens.push(TokenType::Const);
744 /// Expects and consumes a `+`. if `+=` is seen, replaces it with a `=`
745 /// and continues. If a `+` is not seen, returns `false`.
747 /// This is used when token-splitting `+=` into `+`.
748 /// See issue #47856 for an example of when this may occur.
749 fn eat_plus(&mut self) -> bool {
750 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
752 token::BinOp(token::Plus) => {
756 token::BinOpEq(token::Plus) => {
757 let span = self.span.with_lo(self.span.lo() + BytePos(1));
758 self.bump_with(token::Eq, span);
766 /// Checks to see if the next token is either `+` or `+=`.
767 /// Otherwise returns `false`.
768 fn check_plus(&mut self) -> bool {
769 if self.token.is_like_plus() {
773 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
778 /// Expects and consumes an `&`. If `&&` is seen, replaces it with a single
779 /// `&` and continues. If an `&` is not seen, signals an error.
780 fn expect_and(&mut self) -> PResult<'a, ()> {
781 self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
783 token::BinOp(token::And) => {
788 let span = self.span.with_lo(self.span.lo() + BytePos(1));
789 Ok(self.bump_with(token::BinOp(token::And), span))
791 _ => self.unexpected()
795 /// Expects and consumes an `|`. If `||` is seen, replaces it with a single
796 /// `|` and continues. If an `|` is not seen, signals an error.
797 fn expect_or(&mut self) -> PResult<'a, ()> {
798 self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or)));
800 token::BinOp(token::Or) => {
805 let span = self.span.with_lo(self.span.lo() + BytePos(1));
806 Ok(self.bump_with(token::BinOp(token::Or), span))
808 _ => self.unexpected()
812 fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
813 literal::expect_no_suffix(&self.sess.span_diagnostic, sp, kind, suffix)
816 /// Attempts to consume a `<`. If `<<` is seen, replaces it with a single
817 /// `<` and continue. If `<-` is seen, replaces it with a single `<`
818 /// and continue. If a `<` is not seen, returns false.
820 /// This is meant to be used when parsing generics on a path to get the
822 fn eat_lt(&mut self) -> bool {
823 self.expected_tokens.push(TokenType::Token(token::Lt));
824 let ate = match self.token {
829 token::BinOp(token::Shl) => {
830 let span = self.span.with_lo(self.span.lo() + BytePos(1));
831 self.bump_with(token::Lt, span);
835 let span = self.span.with_lo(self.span.lo() + BytePos(1));
836 self.bump_with(token::BinOp(token::Minus), span);
843 // See doc comment for `unmatched_angle_bracket_count`.
844 self.unmatched_angle_bracket_count += 1;
845 self.max_angle_bracket_count += 1;
846 debug!("eat_lt: (increment) count={:?}", self.unmatched_angle_bracket_count);
852 fn expect_lt(&mut self) -> PResult<'a, ()> {
860 /// Expects and consumes a single `>` token. if a `>>` is seen, replaces it
861 /// with a single `>` and continues. If a `>` is not seen, signals an error.
862 fn expect_gt(&mut self) -> PResult<'a, ()> {
863 self.expected_tokens.push(TokenType::Token(token::Gt));
864 let ate = match self.token {
869 token::BinOp(token::Shr) => {
870 let span = self.span.with_lo(self.span.lo() + BytePos(1));
871 Some(self.bump_with(token::Gt, span))
873 token::BinOpEq(token::Shr) => {
874 let span = self.span.with_lo(self.span.lo() + BytePos(1));
875 Some(self.bump_with(token::Ge, span))
878 let span = self.span.with_lo(self.span.lo() + BytePos(1));
879 Some(self.bump_with(token::Eq, span))
886 // See doc comment for `unmatched_angle_bracket_count`.
887 if self.unmatched_angle_bracket_count > 0 {
888 self.unmatched_angle_bracket_count -= 1;
889 debug!("expect_gt: (decrement) count={:?}", self.unmatched_angle_bracket_count);
894 None => self.unexpected(),
898 /// Parses a sequence, including the closing delimiter. The function
899 /// `f` must consume tokens until reaching the next separator or
901 pub fn parse_seq_to_end<T, F>(&mut self,
905 -> PResult<'a, Vec<T>> where
906 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
908 let (val, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
915 /// Parses a sequence, not including the closing delimiter. The function
916 /// `f` must consume tokens until reaching the next separator or
918 pub fn parse_seq_to_before_end<T, F>(
923 ) -> PResult<'a, (Vec<T>, bool)>
924 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
926 self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
929 crate fn parse_seq_to_before_tokens<T, F>(
931 kets: &[&token::Token],
933 expect: TokenExpectType,
935 ) -> PResult<'a, (Vec<T>, bool /* recovered */)>
936 where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
938 let mut first = true;
939 let mut recovered = false;
941 while !kets.iter().any(|k| {
943 TokenExpectType::Expect => self.check(k),
944 TokenExpectType::NoExpect => self.token == **k,
948 token::CloseDelim(..) | token::Eof => break,
951 if let Some(ref t) = sep.sep {
955 match self.expect(t) {
962 // Attempt to keep parsing if it was a similar separator
963 if let Some(ref tokens) = t.similar_tokens() {
964 if tokens.contains(&self.token) {
969 // Attempt to keep parsing if it was an omitted separator
984 if sep.trailing_sep_allowed && kets.iter().any(|k| {
986 TokenExpectType::Expect => self.check(k),
987 TokenExpectType::NoExpect => self.token == **k,
1000 /// Parses a sequence, including the closing delimiter. The function
1001 /// `f` must consume tokens until reaching the next separator or
1002 /// closing bracket.
1003 fn parse_unspanned_seq<T, F>(
1009 ) -> PResult<'a, Vec<T>> where
1010 F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
1013 let (result, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
1020 /// Advance the parser by one token
1021 pub fn bump(&mut self) {
1022 if self.prev_token_kind == PrevTokenKind::Eof {
1023 // Bumping after EOF is a bad sign, usually an infinite loop.
1024 self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
1027 self.prev_span = self.meta_var_span.take().unwrap_or(self.span);
1029 // Record last token kind for possible error recovery.
1030 self.prev_token_kind = match self.token {
1031 token::DocComment(..) => PrevTokenKind::DocComment,
1032 token::Comma => PrevTokenKind::Comma,
1033 token::BinOp(token::Plus) => PrevTokenKind::Plus,
1034 token::BinOp(token::Or) => PrevTokenKind::BitOr,
1035 token::Interpolated(..) => PrevTokenKind::Interpolated,
1036 token::Eof => PrevTokenKind::Eof,
1037 token::Ident(..) => PrevTokenKind::Ident,
1038 _ => PrevTokenKind::Other,
1041 let next = self.next_tok();
1042 self.span = next.sp;
1043 self.token = next.tok;
1044 self.expected_tokens.clear();
1045 // check after each token
1046 self.process_potential_macro_variable();
1049 /// Advance the parser using provided token as a next one. Use this when
1050 /// consuming a part of a token. For example a single `<` from `<<`.
1051 fn bump_with(&mut self, next: token::Token, span: Span) {
1052 self.prev_span = self.span.with_hi(span.lo());
1053 // It would be incorrect to record the kind of the current token, but
1054 // fortunately for tokens currently using `bump_with`, the
1055 // prev_token_kind will be of no use anyway.
1056 self.prev_token_kind = PrevTokenKind::Other;
1059 self.expected_tokens.clear();
1062 pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where
1063 F: FnOnce(&token::Token) -> R,
1066 return f(&self.token)
1069 f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1070 Some(tree) => match tree {
1071 TokenTree::Token(_, tok) => tok,
1072 TokenTree::Delimited(_, delim, _) => token::OpenDelim(delim),
1074 None => token::CloseDelim(self.token_cursor.frame.delim),
1078 crate fn look_ahead_span(&self, dist: usize) -> Span {
1083 match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
1084 Some(TokenTree::Token(span, _)) => span,
1085 Some(TokenTree::Delimited(span, ..)) => span.entire(),
1086 None => self.look_ahead_span(dist - 1),
1090 /// Is the current token one of the keywords that signals a bare function type?
1091 fn token_is_bare_fn_keyword(&mut self) -> bool {
1092 self.check_keyword(kw::Fn) ||
1093 self.check_keyword(kw::Unsafe) ||
1094 self.check_keyword(kw::Extern)
1097 /// Parses a `TyKind::BareFn` type.
1098 fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
1101 [unsafe] [extern "ABI"] fn (S) -> T
1111 let unsafety = self.parse_unsafety();
1112 let abi = if self.eat_keyword(kw::Extern) {
1113 self.parse_opt_abi()?.unwrap_or(Abi::C)
1118 self.expect_keyword(kw::Fn)?;
1119 let (inputs, c_variadic) = self.parse_fn_args(false, true)?;
1120 let ret_ty = self.parse_ret_ty(false)?;
1121 let decl = P(FnDecl {
1126 Ok(TyKind::BareFn(P(BareFnTy {
1134 /// Parses asyncness: `async` or nothing.
1135 fn parse_asyncness(&mut self) -> IsAsync {
1136 if self.eat_keyword(kw::Async) {
1138 closure_id: ast::DUMMY_NODE_ID,
1139 return_impl_trait_id: ast::DUMMY_NODE_ID,
1140 arguments: Vec::new(),
1147 /// Parses unsafety: `unsafe` or nothing.
1148 fn parse_unsafety(&mut self) -> Unsafety {
1149 if self.eat_keyword(kw::Unsafe) {
1156 /// Parses the items in a trait declaration.
1157 pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> {
1158 maybe_whole!(self, NtTraitItem, |x| x);
1159 let attrs = self.parse_outer_attributes()?;
1160 let mut unclosed_delims = vec![];
1161 let (mut item, tokens) = self.collect_tokens(|this| {
1162 let item = this.parse_trait_item_(at_end, attrs);
1163 unclosed_delims.append(&mut this.unclosed_delims);
1166 self.unclosed_delims.append(&mut unclosed_delims);
1167 // See `parse_item` for why this clause is here.
1168 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
1169 item.tokens = Some(tokens);
1174 fn parse_trait_item_(&mut self,
1176 mut attrs: Vec<Attribute>) -> PResult<'a, TraitItem> {
1179 let (name, node, generics) = if self.eat_keyword(kw::Type) {
1180 self.parse_trait_item_assoc_ty()?
1181 } else if self.is_const_item() {
1182 self.expect_keyword(kw::Const)?;
1183 let ident = self.parse_ident()?;
1184 self.expect(&token::Colon)?;
1185 let ty = self.parse_ty()?;
1186 let default = if self.eat(&token::Eq) {
1187 let expr = self.parse_expr()?;
1188 self.expect(&token::Semi)?;
1191 self.expect(&token::Semi)?;
1194 (ident, TraitItemKind::Const(ty, default), ast::Generics::default())
1195 } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
1196 // trait item macro.
1197 (Ident::invalid(), ast::TraitItemKind::Macro(mac), ast::Generics::default())
1199 let (constness, unsafety, mut asyncness, abi) = self.parse_fn_front_matter()?;
1201 let ident = self.parse_ident()?;
1202 let mut generics = self.parse_generics()?;
1204 let mut decl = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
1205 // This is somewhat dubious; We don't want to allow
1206 // argument names to be left off if there is a
1209 // We don't allow argument names to be left off in edition 2018.
1210 p.parse_arg_general(p.span.rust_2018(), true, false)
1212 generics.where_clause = self.parse_where_clause()?;
1213 self.construct_async_arguments(&mut asyncness, &mut decl);
1215 let sig = ast::MethodSig {
1225 let body = match self.token {
1229 debug!("parse_trait_methods(): parsing required method");
1232 token::OpenDelim(token::Brace) => {
1233 debug!("parse_trait_methods(): parsing provided method");
1235 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1236 attrs.extend(inner_attrs.iter().cloned());
1239 token::Interpolated(ref nt) => {
1241 token::NtBlock(..) => {
1243 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
1244 attrs.extend(inner_attrs.iter().cloned());
1248 return self.expected_semi_or_open_brace();
1253 return self.expected_semi_or_open_brace();
1256 (ident, ast::TraitItemKind::Method(sig, body), generics)
1260 id: ast::DUMMY_NODE_ID,
1265 span: lo.to(self.prev_span),
1270 /// Parses an optional return type `[ -> TY ]` in a function declaration.
1271 fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> {
1272 if self.eat(&token::RArrow) {
1273 Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true, false)?))
1275 Ok(FunctionRetTy::Default(self.span.shrink_to_lo()))
1280 pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
1281 self.parse_ty_common(true, true, false)
1284 /// Parses a type in restricted contexts where `+` is not permitted.
1286 /// Example 1: `&'a TYPE`
1287 /// `+` is prohibited to maintain operator priority (P(+) < P(&)).
1288 /// Example 2: `value1 as TYPE + value2`
1289 /// `+` is prohibited to avoid interactions with expression grammar.
1290 fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
1291 self.parse_ty_common(false, true, false)
1294 fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool,
1295 allow_c_variadic: bool) -> PResult<'a, P<Ty>> {
1296 maybe_recover_from_interpolated_ty_qpath!(self, allow_qpath_recovery);
1297 maybe_whole!(self, NtTy, |x| x);
1300 let mut impl_dyn_multi = false;
1301 let node = if self.eat(&token::OpenDelim(token::Paren)) {
1302 // `(TYPE)` is a parenthesized type.
1303 // `(TYPE,)` is a tuple with a single field of type TYPE.
1304 let mut ts = vec![];
1305 let mut last_comma = false;
1306 while self.token != token::CloseDelim(token::Paren) {
1307 ts.push(self.parse_ty()?);
1308 if self.eat(&token::Comma) {
1315 let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
1316 self.expect(&token::CloseDelim(token::Paren))?;
1318 if ts.len() == 1 && !last_comma {
1319 let ty = ts.into_iter().nth(0).unwrap().into_inner();
1320 let maybe_bounds = allow_plus && self.token.is_like_plus();
1322 // `(TY_BOUND_NOPAREN) + BOUND + ...`.
1323 TyKind::Path(None, ref path) if maybe_bounds => {
1324 self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
1326 TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
1327 if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
1328 let path = match bounds[0] {
1329 GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
1330 GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
1332 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1335 _ => TyKind::Paren(P(ty))
1340 } else if self.eat(&token::Not) {
1343 } else if self.eat(&token::BinOp(token::Star)) {
1345 TyKind::Ptr(self.parse_ptr()?)
1346 } else if self.eat(&token::OpenDelim(token::Bracket)) {
1348 let t = self.parse_ty()?;
1349 // Parse optional `; EXPR` in `[TYPE; EXPR]`
1350 let t = match self.maybe_parse_fixed_length_of_vec()? {
1351 None => TyKind::Slice(t),
1352 Some(length) => TyKind::Array(t, AnonConst {
1353 id: ast::DUMMY_NODE_ID,
1357 self.expect(&token::CloseDelim(token::Bracket))?;
1359 } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
1362 self.parse_borrowed_pointee()?
1363 } else if self.eat_keyword_noexpect(kw::Typeof) {
1365 // In order to not be ambiguous, the type must be surrounded by parens.
1366 self.expect(&token::OpenDelim(token::Paren))?;
1368 id: ast::DUMMY_NODE_ID,
1369 value: self.parse_expr()?,
1371 self.expect(&token::CloseDelim(token::Paren))?;
1373 } else if self.eat_keyword(kw::Underscore) {
1374 // A type to be inferred `_`
1376 } else if self.token_is_bare_fn_keyword() {
1377 // Function pointer type
1378 self.parse_ty_bare_fn(Vec::new())?
1379 } else if self.check_keyword(kw::For) {
1380 // Function pointer type or bound list (trait object type) starting with a poly-trait.
1381 // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
1382 // `for<'lt> Trait1<'lt> + Trait2 + 'a`
1384 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
1385 if self.token_is_bare_fn_keyword() {
1386 self.parse_ty_bare_fn(lifetime_defs)?
1388 let path = self.parse_path(PathStyle::Type)?;
1389 let parse_plus = allow_plus && self.check_plus();
1390 self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
1392 } else if self.eat_keyword(kw::Impl) {
1393 // Always parse bounds greedily for better error recovery.
1394 let bounds = self.parse_generic_bounds(None)?;
1395 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1396 TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
1397 } else if self.check_keyword(kw::Dyn) &&
1398 (self.span.rust_2018() ||
1399 self.look_ahead(1, |t| t.can_begin_bound() &&
1400 !can_continue_type_after_non_fn_ident(t))) {
1401 self.bump(); // `dyn`
1402 // Always parse bounds greedily for better error recovery.
1403 let bounds = self.parse_generic_bounds(None)?;
1404 impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
1405 TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
1406 } else if self.check(&token::Question) ||
1407 self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
1408 // Bound list (trait object type)
1409 TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus, None)?,
1410 TraitObjectSyntax::None)
1411 } else if self.eat_lt() {
1413 let (qself, path) = self.parse_qpath(PathStyle::Type)?;
1414 TyKind::Path(Some(qself), path)
1415 } else if self.token.is_path_start() {
1417 let path = self.parse_path(PathStyle::Type)?;
1418 if self.eat(&token::Not) {
1419 // Macro invocation in type position
1420 let (delim, tts) = self.expect_delimited_token_tree()?;
1421 let node = Mac_ { path, tts, delim };
1422 TyKind::Mac(respan(lo.to(self.prev_span), node))
1424 // Just a type path or bound list (trait object type) starting with a trait.
1426 // `Trait1 + Trait2 + 'a`
1427 if allow_plus && self.check_plus() {
1428 self.parse_remaining_bounds(Vec::new(), path, lo, true)?
1430 TyKind::Path(None, path)
1433 } else if self.check(&token::DotDotDot) {
1434 if allow_c_variadic {
1435 self.eat(&token::DotDotDot);
1438 return Err(self.fatal(
1439 "only foreign functions are allowed to be C-variadic"
1443 let msg = format!("expected type, found {}", self.this_token_descr());
1444 return Err(self.fatal(&msg));
1447 let span = lo.to(self.prev_span);
1448 let ty = P(Ty { node, span, id: ast::DUMMY_NODE_ID });
1450 // Try to recover from use of `+` with incorrect priority.
1451 self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
1452 self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
1453 self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)
1456 fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
1457 lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
1458 let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));
1459 let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
1461 self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
1462 bounds.append(&mut self.parse_generic_bounds(Some(self.prev_span))?);
1464 Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
1467 fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
1468 let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
1469 let mutbl = self.parse_mutability();
1470 let ty = self.parse_ty_no_plus()?;
1471 return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl }));
1474 fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
1475 let mutbl = if self.eat_keyword(kw::Mut) {
1477 } else if self.eat_keyword(kw::Const) {
1478 Mutability::Immutable
1480 let span = self.prev_span;
1481 let msg = "expected mut or const in raw pointer type";
1482 self.struct_span_err(span, msg)
1483 .span_label(span, msg)
1484 .help("use `*mut T` or `*const T` as appropriate")
1486 Mutability::Immutable
1488 let t = self.parse_ty_no_plus()?;
1489 Ok(MutTy { ty: t, mutbl: mutbl })
1492 fn is_named_argument(&self) -> bool {
1493 let offset = match self.token {
1494 token::Interpolated(ref nt) => match **nt {
1495 token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
1498 token::BinOp(token::And) | token::AndAnd => 1,
1499 _ if self.token.is_keyword(kw::Mut) => 1,
1503 self.look_ahead(offset, |t| t.is_ident()) &&
1504 self.look_ahead(offset + 1, |t| t == &token::Colon)
1507 /// Skips unexpected attributes and doc comments in this position and emits an appropriate
1509 /// This version of parse arg doesn't necessarily require identifier names.
1510 fn parse_arg_general(
1513 is_trait_item: bool,
1514 allow_c_variadic: bool,
1515 ) -> PResult<'a, Arg> {
1516 if let Ok(Some(arg)) = self.parse_self_arg() {
1517 return self.recover_bad_self_arg(arg, is_trait_item);
1520 let (pat, ty) = if require_name || self.is_named_argument() {
1521 debug!("parse_arg_general parse_pat (require_name:{})", require_name);
1522 self.eat_incorrect_doc_comment("method arguments");
1523 let pat = self.parse_pat(Some("argument name"))?;
1525 if let Err(mut err) = self.expect(&token::Colon) {
1526 self.argument_without_type(&mut err, pat, require_name, is_trait_item);
1530 self.eat_incorrect_doc_comment("a method argument's type");
1531 (pat, self.parse_ty_common(true, true, allow_c_variadic)?)
1533 debug!("parse_arg_general ident_to_pat");
1534 let parser_snapshot_before_ty = self.clone();
1535 self.eat_incorrect_doc_comment("a method argument's type");
1536 let mut ty = self.parse_ty_common(true, true, allow_c_variadic);
1537 if ty.is_ok() && self.token != token::Comma &&
1538 self.token != token::CloseDelim(token::Paren) {
1539 // This wasn't actually a type, but a pattern looking like a type,
1540 // so we are going to rollback and re-parse for recovery.
1541 ty = self.unexpected();
1545 let ident = Ident::new(kw::Invalid, self.prev_span);
1547 id: ast::DUMMY_NODE_ID,
1548 node: PatKind::Ident(
1549 BindingMode::ByValue(Mutability::Immutable), ident, None),
1555 // If this is a C-variadic argument and we hit an error, return the
1557 if self.token == token::DotDotDot {
1560 // Recover from attempting to parse the argument as a type without pattern.
1562 mem::replace(self, parser_snapshot_before_ty);
1563 self.recover_arg_parse()?
1568 Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID, source: ast::ArgSource::Normal })
1571 /// Parses an argument in a lambda header (e.g., `|arg, arg|`).
1572 fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
1573 let pat = self.parse_pat(Some("argument name"))?;
1574 let t = if self.eat(&token::Colon) {
1578 id: ast::DUMMY_NODE_ID,
1579 node: TyKind::Infer,
1580 span: self.prev_span,
1586 id: ast::DUMMY_NODE_ID,
1587 source: ast::ArgSource::Normal,
1591 fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
1592 if self.eat(&token::Semi) {
1593 Ok(Some(self.parse_expr()?))
1599 /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`).
1600 crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
1601 maybe_whole_expr!(self);
1603 let minus_lo = self.span;
1604 let minus_present = self.eat(&token::BinOp(token::Minus));
1606 let literal = self.parse_lit()?;
1607 let hi = self.prev_span;
1608 let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
1611 let minus_hi = self.prev_span;
1612 let unary = self.mk_unary(UnOp::Neg, expr);
1613 Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
1619 fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
1621 token::Ident(ident, _) if self.token.is_path_segment_keyword() => {
1622 let span = self.span;
1624 Ok(Ident::new(ident.name, span))
1626 _ => self.parse_ident(),
1630 fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
1632 token::Ident(ident, false) if ident.name == kw::Underscore => {
1633 let span = self.span;
1635 Ok(Ident::new(ident.name, span))
1637 _ => self.parse_ident(),
1641 /// Parses a qualified path.
1642 /// Assumes that the leading `<` has been parsed already.
1644 /// `qualified_path = <type [as trait_ref]>::path`
1649 /// `<T as U>::F::a<S>` (without disambiguator)
1650 /// `<T as U>::F::a::<S>` (with disambiguator)
1651 fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::Path)> {
1652 let lo = self.prev_span;
1653 let ty = self.parse_ty()?;
1655 // `path` will contain the prefix of the path up to the `>`,
1656 // if any (e.g., `U` in the `<T as U>::*` examples
1657 // above). `path_span` has the span of that path, or an empty
1658 // span in the case of something like `<T>::Bar`.
1659 let (mut path, path_span);
1660 if self.eat_keyword(kw::As) {
1661 let path_lo = self.span;
1662 path = self.parse_path(PathStyle::Type)?;
1663 path_span = path_lo.to(self.prev_span);
1665 path = ast::Path { segments: Vec::new(), span: DUMMY_SP };
1666 path_span = self.span.to(self.span);
1669 // See doc comment for `unmatched_angle_bracket_count`.
1670 self.expect(&token::Gt)?;
1671 if self.unmatched_angle_bracket_count > 0 {
1672 self.unmatched_angle_bracket_count -= 1;
1673 debug!("parse_qpath: (decrement) count={:?}", self.unmatched_angle_bracket_count);
1676 self.expect(&token::ModSep)?;
1678 let qself = QSelf { ty, path_span, position: path.segments.len() };
1679 self.parse_path_segments(&mut path.segments, style)?;
1681 Ok((qself, ast::Path { segments: path.segments, span: lo.to(self.prev_span) }))
1684 /// Parses simple paths.
1686 /// `path = [::] segment+`
1687 /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
1690 /// `a::b::C<D>` (without disambiguator)
1691 /// `a::b::C::<D>` (with disambiguator)
1692 /// `Fn(Args)` (without disambiguator)
1693 /// `Fn::(Args)` (with disambiguator)
1694 pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
1695 maybe_whole!(self, NtPath, |path| {
1696 if style == PathStyle::Mod &&
1697 path.segments.iter().any(|segment| segment.args.is_some()) {
1698 self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
1703 let lo = self.meta_var_span.unwrap_or(self.span);
1704 let mut segments = Vec::new();
1705 let mod_sep_ctxt = self.span.ctxt();
1706 if self.eat(&token::ModSep) {
1707 segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
1709 self.parse_path_segments(&mut segments, style)?;
1711 Ok(ast::Path { segments, span: lo.to(self.prev_span) })
1714 /// Like `parse_path`, but also supports parsing `Word` meta items into paths for
1715 /// backwards-compatibility. This is used when parsing derive macro paths in `#[derive]`
1717 pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
1718 let meta_ident = match self.token {
1719 token::Interpolated(ref nt) => match **nt {
1720 token::NtMeta(ref meta) => match meta.node {
1721 ast::MetaItemKind::Word => Some(meta.path.clone()),
1728 if let Some(path) = meta_ident {
1732 self.parse_path(style)
1735 crate fn parse_path_segments(&mut self,
1736 segments: &mut Vec<PathSegment>,
1738 -> PResult<'a, ()> {
1740 let segment = self.parse_path_segment(style)?;
1741 if style == PathStyle::Expr {
1742 // In order to check for trailing angle brackets, we must have finished
1743 // recursing (`parse_path_segment` can indirectly call this function),
1744 // that is, the next token must be the highlighted part of the below example:
1746 // `Foo::<Bar as Baz<T>>::Qux`
1749 // As opposed to the below highlight (if we had only finished the first
1752 // `Foo::<Bar as Baz<T>>::Qux`
1755 // `PathStyle::Expr` is only provided at the root invocation and never in
1756 // `parse_path_segment` to recurse and therefore can be checked to maintain
1758 self.check_trailing_angle_brackets(&segment, token::ModSep);
1760 segments.push(segment);
1762 if self.is_import_coupler() || !self.eat(&token::ModSep) {
1768 fn parse_path_segment(&mut self, style: PathStyle) -> PResult<'a, PathSegment> {
1769 let ident = self.parse_path_segment_ident()?;
1771 let is_args_start = |token: &token::Token| match *token {
1772 token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren)
1773 | token::LArrow => true,
1776 let check_args_start = |this: &mut Self| {
1777 this.expected_tokens.extend_from_slice(
1778 &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
1780 is_args_start(&this.token)
1783 Ok(if style == PathStyle::Type && check_args_start(self) ||
1784 style != PathStyle::Mod && self.check(&token::ModSep)
1785 && self.look_ahead(1, |t| is_args_start(t)) {
1786 // We use `style == PathStyle::Expr` to check if this is in a recursion or not. If
1787 // it isn't, then we reset the unmatched angle bracket count as we're about to start
1788 // parsing a new path.
1789 if style == PathStyle::Expr {
1790 self.unmatched_angle_bracket_count = 0;
1791 self.max_angle_bracket_count = 0;
1794 // Generic arguments are found - `<`, `(`, `::<` or `::(`.
1795 self.eat(&token::ModSep);
1797 let args = if self.eat_lt() {
1799 let (args, bindings) =
1800 self.parse_generic_args_with_leaning_angle_bracket_recovery(style, lo)?;
1802 let span = lo.to(self.prev_span);
1803 AngleBracketedArgs { args, bindings, span }.into()
1807 let (inputs, recovered) = self.parse_seq_to_before_tokens(
1808 &[&token::CloseDelim(token::Paren)],
1809 SeqSep::trailing_allowed(token::Comma),
1810 TokenExpectType::Expect,
1815 let span = lo.to(self.prev_span);
1816 let output = if self.eat(&token::RArrow) {
1817 Some(self.parse_ty_common(false, false, false)?)
1821 ParenthesizedArgs { inputs, output, span }.into()
1824 PathSegment { ident, args, id: ast::DUMMY_NODE_ID }
1826 // Generic arguments are not found.
1827 PathSegment::from_ident(ident)
1831 crate fn check_lifetime(&mut self) -> bool {
1832 self.expected_tokens.push(TokenType::Lifetime);
1833 self.token.is_lifetime()
1836 /// Parses a single lifetime `'a` or panics.
1837 crate fn expect_lifetime(&mut self) -> Lifetime {
1838 if let Some(ident) = self.token.lifetime() {
1839 let span = self.span;
1841 Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
1843 self.span_bug(self.span, "not a lifetime")
1847 fn eat_label(&mut self) -> Option<Label> {
1848 if let Some(ident) = self.token.lifetime() {
1849 let span = self.span;
1851 Some(Label { ident: Ident::new(ident.name, span) })
1857 /// Parses mutability (`mut` or nothing).
1858 fn parse_mutability(&mut self) -> Mutability {
1859 if self.eat_keyword(kw::Mut) {
1862 Mutability::Immutable
1866 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
1867 if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) = self.token {
1868 self.expect_no_suffix(self.span, "a tuple index", suffix);
1870 Ok(Ident::new(symbol, self.prev_span))
1872 self.parse_ident_common(false)
1876 /// Parse ident (COLON expr)?
1877 fn parse_field(&mut self) -> PResult<'a, Field> {
1878 let attrs = self.parse_outer_attributes()?;
1881 // Check if a colon exists one ahead. This means we're parsing a fieldname.
1882 let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| {
1883 t == &token::Colon || t == &token::Eq
1885 let fieldname = self.parse_field_name()?;
1887 // Check for an equals token. This means the source incorrectly attempts to
1888 // initialize a field with an eq rather than a colon.
1889 if self.token == token::Eq {
1891 .struct_span_err(self.span, "expected `:`, found `=`")
1893 fieldname.span.shrink_to_hi().to(self.span),
1894 "replace equals symbol with a colon",
1896 Applicability::MachineApplicable,
1901 (fieldname, self.parse_expr()?, false)
1903 let fieldname = self.parse_ident_common(false)?;
1905 // Mimic `x: x` for the `x` field shorthand.
1906 let path = ast::Path::from_ident(fieldname);
1907 let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
1908 (fieldname, expr, true)
1912 span: lo.to(expr.span),
1915 attrs: attrs.into(),
1919 crate fn mk_expr(&self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
1920 P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID })
1923 fn mk_unary(&self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
1924 ExprKind::Unary(unop, expr)
1927 fn mk_binary(&self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
1928 ExprKind::Binary(binop, lhs, rhs)
1931 fn mk_call(&self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
1932 ExprKind::Call(f, args)
1935 fn mk_index(&self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
1936 ExprKind::Index(expr, idx)
1940 start: Option<P<Expr>>,
1941 end: Option<P<Expr>>,
1942 limits: RangeLimits)
1943 -> PResult<'a, ast::ExprKind> {
1944 if end.is_none() && limits == RangeLimits::Closed {
1945 Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd))
1947 Ok(ExprKind::Range(start, end, limits))
1951 fn mk_assign_op(&self, binop: ast::BinOp,
1952 lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
1953 ExprKind::AssignOp(binop, lhs, rhs)
1956 fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, TokenStream)> {
1957 let delim = match self.token {
1958 token::OpenDelim(delim) => delim,
1960 let msg = "expected open delimiter";
1961 let mut err = self.fatal(msg);
1962 err.span_label(self.span, msg);
1966 let tts = match self.parse_token_tree() {
1967 TokenTree::Delimited(_, _, tts) => tts,
1968 _ => unreachable!(),
1970 let delim = match delim {
1971 token::Paren => MacDelimiter::Parenthesis,
1972 token::Bracket => MacDelimiter::Bracket,
1973 token::Brace => MacDelimiter::Brace,
1974 token::NoDelim => self.bug("unexpected no delimiter"),
1976 Ok((delim, tts.into()))
1979 /// At the bottom (top?) of the precedence hierarchy,
1980 /// Parses things like parenthesized exprs, macros, `return`, etc.
1982 /// N.B., this does not parse outer attributes, and is private because it only works
1983 /// correctly if called from `parse_dot_or_call_expr()`.
1984 fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
1985 maybe_recover_from_interpolated_ty_qpath!(self, true);
1986 maybe_whole_expr!(self);
1988 // Outer attributes are already parsed and will be
1989 // added to the return value after the fact.
1991 // Therefore, prevent sub-parser from parsing
1992 // attributes by giving them a empty "already parsed" list.
1993 let mut attrs = ThinVec::new();
1996 let mut hi = self.span;
2000 // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2002 token::OpenDelim(token::Paren) => {
2005 attrs.extend(self.parse_inner_attributes()?);
2007 // (e) is parenthesized e
2008 // (e,) is a tuple with only one field, e
2009 let mut es = vec![];
2010 let mut trailing_comma = false;
2011 let mut recovered = false;
2012 while self.token != token::CloseDelim(token::Paren) {
2013 es.push(match self.parse_expr() {
2016 // recover from parse error in tuple list
2017 return Ok(self.recover_seq_parse_error(token::Paren, lo, Err(err)));
2020 recovered = self.expect_one_of(
2022 &[token::Comma, token::CloseDelim(token::Paren)],
2024 if self.eat(&token::Comma) {
2025 trailing_comma = true;
2027 trailing_comma = false;
2035 hi = self.prev_span;
2036 ex = if es.len() == 1 && !trailing_comma {
2037 ExprKind::Paren(es.into_iter().nth(0).unwrap())
2042 token::OpenDelim(token::Brace) => {
2043 return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
2045 token::BinOp(token::Or) | token::OrOr => {
2046 return self.parse_lambda_expr(attrs);
2048 token::OpenDelim(token::Bracket) => {
2051 attrs.extend(self.parse_inner_attributes()?);
2053 if self.eat(&token::CloseDelim(token::Bracket)) {
2055 ex = ExprKind::Array(Vec::new());
2058 let first_expr = self.parse_expr()?;
2059 if self.eat(&token::Semi) {
2060 // Repeating array syntax: [ 0; 512 ]
2061 let count = AnonConst {
2062 id: ast::DUMMY_NODE_ID,
2063 value: self.parse_expr()?,
2065 self.expect(&token::CloseDelim(token::Bracket))?;
2066 ex = ExprKind::Repeat(first_expr, count);
2067 } else if self.eat(&token::Comma) {
2068 // Vector with two or more elements.
2069 let remaining_exprs = self.parse_seq_to_end(
2070 &token::CloseDelim(token::Bracket),
2071 SeqSep::trailing_allowed(token::Comma),
2072 |p| Ok(p.parse_expr()?)
2074 let mut exprs = vec![first_expr];
2075 exprs.extend(remaining_exprs);
2076 ex = ExprKind::Array(exprs);
2078 // Vector with one element.
2079 self.expect(&token::CloseDelim(token::Bracket))?;
2080 ex = ExprKind::Array(vec![first_expr]);
2083 hi = self.prev_span;
2087 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
2089 return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
2091 if self.span.rust_2018() && self.check_keyword(kw::Async) {
2092 return if self.is_async_block() { // check for `async {` and `async move {`
2093 self.parse_async_block(attrs)
2095 self.parse_lambda_expr(attrs)
2098 if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
2099 return self.parse_lambda_expr(attrs);
2101 if self.eat_keyword(kw::If) {
2102 return self.parse_if_expr(attrs);
2104 if self.eat_keyword(kw::For) {
2105 let lo = self.prev_span;
2106 return self.parse_for_expr(None, lo, attrs);
2108 if self.eat_keyword(kw::While) {
2109 let lo = self.prev_span;
2110 return self.parse_while_expr(None, lo, attrs);
2112 if let Some(label) = self.eat_label() {
2113 let lo = label.ident.span;
2114 self.expect(&token::Colon)?;
2115 if self.eat_keyword(kw::While) {
2116 return self.parse_while_expr(Some(label), lo, attrs)
2118 if self.eat_keyword(kw::For) {
2119 return self.parse_for_expr(Some(label), lo, attrs)
2121 if self.eat_keyword(kw::Loop) {
2122 return self.parse_loop_expr(Some(label), lo, attrs)
2124 if self.token == token::OpenDelim(token::Brace) {
2125 return self.parse_block_expr(Some(label),
2127 BlockCheckMode::Default,
2130 let msg = "expected `while`, `for`, `loop` or `{` after a label";
2131 let mut err = self.fatal(msg);
2132 err.span_label(self.span, msg);
2135 if self.eat_keyword(kw::Loop) {
2136 let lo = self.prev_span;
2137 return self.parse_loop_expr(None, lo, attrs);
2139 if self.eat_keyword(kw::Continue) {
2140 let label = self.eat_label();
2141 let ex = ExprKind::Continue(label);
2142 let hi = self.prev_span;
2143 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2145 if self.eat_keyword(kw::Match) {
2146 let match_sp = self.prev_span;
2147 return self.parse_match_expr(attrs).map_err(|mut err| {
2148 err.span_label(match_sp, "while parsing this match expression");
2152 if self.eat_keyword(kw::Unsafe) {
2153 return self.parse_block_expr(
2156 BlockCheckMode::Unsafe(ast::UserProvided),
2159 if self.is_do_catch_block() {
2160 let mut db = self.fatal("found removed `do catch` syntax");
2161 db.help("Following RFC #2388, the new non-placeholder syntax is `try`");
2164 if self.is_try_block() {
2166 assert!(self.eat_keyword(kw::Try));
2167 return self.parse_try_block(lo, attrs);
2169 if self.eat_keyword(kw::Return) {
2170 if self.token.can_begin_expr() {
2171 let e = self.parse_expr()?;
2173 ex = ExprKind::Ret(Some(e));
2175 ex = ExprKind::Ret(None);
2177 } else if self.eat_keyword(kw::Break) {
2178 let label = self.eat_label();
2179 let e = if self.token.can_begin_expr()
2180 && !(self.token == token::OpenDelim(token::Brace)
2181 && self.restrictions.contains(
2182 Restrictions::NO_STRUCT_LITERAL)) {
2183 Some(self.parse_expr()?)
2187 ex = ExprKind::Break(label, e);
2188 hi = self.prev_span;
2189 } else if self.eat_keyword(kw::Yield) {
2190 if self.token.can_begin_expr() {
2191 let e = self.parse_expr()?;
2193 ex = ExprKind::Yield(Some(e));
2195 ex = ExprKind::Yield(None);
2197 } else if self.token.is_keyword(kw::Let) {
2198 // Catch this syntax error here, instead of in `parse_ident`, so
2199 // that we can explicitly mention that let is not to be used as an expression
2200 let mut db = self.fatal("expected expression, found statement (`let`)");
2201 db.span_label(self.span, "expected expression");
2202 db.note("variable declaration using `let` is a statement");
2204 } else if self.span.rust_2018() && self.eat_keyword(kw::Await) {
2205 let (await_hi, e_kind) = self.parse_await_macro_or_alt(lo, self.prev_span)?;
2208 } else if self.token.is_path_start() {
2209 let path = self.parse_path(PathStyle::Expr)?;
2211 // `!`, as an operator, is prefix, so we know this isn't that
2212 if self.eat(&token::Not) {
2213 // MACRO INVOCATION expression
2214 let (delim, tts) = self.expect_delimited_token_tree()?;
2215 hi = self.prev_span;
2216 ex = ExprKind::Mac(respan(lo.to(hi), Mac_ { path, tts, delim }));
2217 } else if self.check(&token::OpenDelim(token::Brace)) {
2218 if let Some(expr) = self.maybe_parse_struct_expr(lo, &path, &attrs) {
2222 ex = ExprKind::Path(None, path);
2226 ex = ExprKind::Path(None, path);
2229 if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
2230 // Don't complain about bare semicolons after unclosed braces
2231 // recovery in order to keep the error count down. Fixing the
2232 // delimiters will possibly also fix the bare semicolon found in
2233 // expression context. For example, silence the following error:
2235 // error: expected expression, found `;`
2239 // | ^ expected expression
2242 return Ok(self.mk_expr(self.span, ExprKind::Err, ThinVec::new()));
2244 match self.parse_literal_maybe_minus() {
2247 ex = expr.node.clone();
2250 self.cancel(&mut err);
2251 return Err(self.expected_expression_found());
2258 let expr = self.mk_expr(lo.to(hi), ex, attrs);
2259 self.maybe_recover_from_bad_qpath(expr, true)
2262 /// Parse `await!(<expr>)` calls, or alternatively recover from incorrect but reasonable
2263 /// alternative syntaxes `await <expr>`, `await? <expr>`, `await(<expr>)` and
2264 /// `await { <expr> }`.
2265 fn parse_await_macro_or_alt(
2269 ) -> PResult<'a, (Span, ExprKind)> {
2270 if self.token == token::Not {
2271 // Handle correct `await!(<expr>)`.
2272 // FIXME: make this an error when `await!` is no longer supported
2273 // https://github.com/rust-lang/rust/issues/60610
2274 self.expect(&token::Not)?;
2275 self.expect(&token::OpenDelim(token::Paren))?;
2276 let expr = self.parse_expr().map_err(|mut err| {
2277 err.span_label(await_sp, "while parsing this await macro call");
2280 self.expect(&token::CloseDelim(token::Paren))?;
2281 Ok((self.prev_span, ExprKind::Await(ast::AwaitOrigin::MacroLike, expr)))
2282 } else { // Handle `await <expr>`.
2283 self.parse_incorrect_await_syntax(lo, await_sp)
2287 fn maybe_parse_struct_expr(
2291 attrs: &ThinVec<Attribute>,
2292 ) -> Option<PResult<'a, P<Expr>>> {
2293 let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
2294 let certainly_not_a_block = || self.look_ahead(1, |t| t.is_ident()) && (
2295 // `{ ident, ` cannot start a block
2296 self.look_ahead(2, |t| t == &token::Comma) ||
2297 self.look_ahead(2, |t| t == &token::Colon) && (
2298 // `{ ident: token, ` cannot start a block
2299 self.look_ahead(4, |t| t == &token::Comma) ||
2300 // `{ ident: ` cannot start a block unless it's a type ascription `ident: Type`
2301 self.look_ahead(3, |t| !t.can_begin_type())
2305 if struct_allowed || certainly_not_a_block() {
2306 // This is a struct literal, but we don't can't accept them here
2307 let expr = self.parse_struct_expr(lo, path.clone(), attrs.clone());
2308 if let (Ok(expr), false) = (&expr, struct_allowed) {
2309 let mut err = self.diagnostic().struct_span_err(
2311 "struct literals are not allowed here",
2313 err.multipart_suggestion(
2314 "surround the struct literal with parentheses",
2316 (lo.shrink_to_lo(), "(".to_string()),
2317 (expr.span.shrink_to_hi(), ")".to_string()),
2319 Applicability::MachineApplicable,
2328 fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Attribute>)
2329 -> PResult<'a, P<Expr>> {
2330 let struct_sp = lo.to(self.prev_span);
2332 let mut fields = Vec::new();
2333 let mut base = None;
2335 attrs.extend(self.parse_inner_attributes()?);
2337 while self.token != token::CloseDelim(token::Brace) {
2338 if self.eat(&token::DotDot) {
2339 let exp_span = self.prev_span;
2340 match self.parse_expr() {
2346 self.recover_stmt();
2349 if self.token == token::Comma {
2350 let mut err = self.sess.span_diagnostic.mut_span_err(
2351 exp_span.to(self.prev_span),
2352 "cannot use a comma after the base struct",
2354 err.span_suggestion_short(
2356 "remove this comma",
2358 Applicability::MachineApplicable
2360 err.note("the base struct must always be the last field");
2362 self.recover_stmt();
2367 let mut recovery_field = None;
2368 if let token::Ident(ident, _) = self.token {
2369 if !self.token.is_reserved_ident() && self.look_ahead(1, |t| *t == token::Colon) {
2370 // Use in case of error after field-looking code: `S { foo: () with a }`
2371 let mut ident = ident.clone();
2372 ident.span = self.span;
2373 recovery_field = Some(ast::Field {
2376 expr: self.mk_expr(self.span, ExprKind::Err, ThinVec::new()),
2377 is_shorthand: false,
2378 attrs: ThinVec::new(),
2382 let mut parsed_field = None;
2383 match self.parse_field() {
2384 Ok(f) => parsed_field = Some(f),
2386 e.span_label(struct_sp, "while parsing this struct");
2389 // If the next token is a comma, then try to parse
2390 // what comes next as additional fields, rather than
2391 // bailing out until next `}`.
2392 if self.token != token::Comma {
2393 self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
2394 if self.token != token::Comma {
2401 match self.expect_one_of(&[token::Comma],
2402 &[token::CloseDelim(token::Brace)]) {
2403 Ok(_) => if let Some(f) = parsed_field.or(recovery_field) {
2404 // only include the field if there's no parse error for the field name
2408 if let Some(f) = recovery_field {
2411 e.span_label(struct_sp, "while parsing this struct");
2413 self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
2414 self.eat(&token::Comma);
2419 let span = lo.to(self.span);
2420 self.expect(&token::CloseDelim(token::Brace))?;
2421 return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
2424 fn parse_or_use_outer_attributes(&mut self,
2425 already_parsed_attrs: Option<ThinVec<Attribute>>)
2426 -> PResult<'a, ThinVec<Attribute>> {
2427 if let Some(attrs) = already_parsed_attrs {
2430 self.parse_outer_attributes().map(|a| a.into())
2434 /// Parses a block or unsafe block.
2435 crate fn parse_block_expr(
2437 opt_label: Option<Label>,
2439 blk_mode: BlockCheckMode,
2440 outer_attrs: ThinVec<Attribute>,
2441 ) -> PResult<'a, P<Expr>> {
2442 self.expect(&token::OpenDelim(token::Brace))?;
2444 let mut attrs = outer_attrs;
2445 attrs.extend(self.parse_inner_attributes()?);
2447 let blk = self.parse_block_tail(lo, blk_mode)?;
2448 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs));
2451 /// Parses `a.b` or `a(13)` or `a[4]` or just `a`.
2452 fn parse_dot_or_call_expr(&mut self,
2453 already_parsed_attrs: Option<ThinVec<Attribute>>)
2454 -> PResult<'a, P<Expr>> {
2455 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2457 let b = self.parse_bottom_expr();
2458 let (span, b) = self.interpolated_or_expr_span(b)?;
2459 self.parse_dot_or_call_expr_with(b, span, attrs)
2462 fn parse_dot_or_call_expr_with(&mut self,
2465 mut attrs: ThinVec<Attribute>)
2466 -> PResult<'a, P<Expr>> {
2467 // Stitch the list of outer attributes onto the return value.
2468 // A little bit ugly, but the best way given the current code
2470 self.parse_dot_or_call_expr_with_(e0, lo)
2472 expr.map(|mut expr| {
2473 attrs.extend::<Vec<_>>(expr.attrs.into());
2476 ExprKind::If(..) | ExprKind::IfLet(..) => {
2477 if !expr.attrs.is_empty() {
2478 // Just point to the first attribute in there...
2479 let span = expr.attrs[0].span;
2482 "attributes are not yet allowed on `if` \
2493 // Assuming we have just parsed `.`, continue parsing into an expression.
2494 fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2495 if self.span.rust_2018() && self.eat_keyword(kw::Await) {
2496 let span = lo.to(self.prev_span);
2497 let await_expr = self.mk_expr(
2499 ExprKind::Await(ast::AwaitOrigin::FieldLike, self_arg),
2502 self.recover_from_await_method_call();
2503 return Ok(await_expr);
2505 let segment = self.parse_path_segment(PathStyle::Expr)?;
2506 self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren));
2508 Ok(match self.token {
2509 token::OpenDelim(token::Paren) => {
2510 // Method call `expr.f()`
2511 let mut args = self.parse_unspanned_seq(
2512 &token::OpenDelim(token::Paren),
2513 &token::CloseDelim(token::Paren),
2514 SeqSep::trailing_allowed(token::Comma),
2515 |p| Ok(p.parse_expr()?)
2517 args.insert(0, self_arg);
2519 let span = lo.to(self.prev_span);
2520 self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
2523 // Field access `expr.f`
2524 if let Some(args) = segment.args {
2525 self.span_err(args.span(),
2526 "field expressions may not have generic arguments");
2529 let span = lo.to(self.prev_span);
2530 self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
2535 fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
2540 while self.eat(&token::Question) {
2541 let hi = self.prev_span;
2542 e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
2546 if self.eat(&token::Dot) {
2548 token::Ident(..) => {
2549 e = self.parse_dot_suffix(e, lo)?;
2551 token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => {
2552 let span = self.span;
2554 let field = ExprKind::Field(e, Ident::new(symbol, span));
2555 e = self.mk_expr(lo.to(span), field, ThinVec::new());
2557 self.expect_no_suffix(span, "a tuple index", suffix);
2559 token::Literal(token::Lit { kind: token::Float, symbol, .. }) => {
2561 let fstr = symbol.as_str();
2562 let msg = format!("unexpected token: `{}`", symbol);
2563 let mut err = self.diagnostic().struct_span_err(self.prev_span, &msg);
2564 err.span_label(self.prev_span, "unexpected token");
2565 if fstr.chars().all(|x| "0123456789.".contains(x)) {
2566 let float = match fstr.parse::<f64>().ok() {
2570 let sugg = pprust::to_string(|s| {
2571 use crate::print::pprust::PrintState;
2575 s.print_usize(float.trunc() as usize)?;
2578 s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
2580 err.span_suggestion(
2581 lo.to(self.prev_span),
2582 "try parenthesizing the first index",
2584 Applicability::MachineApplicable
2591 // FIXME Could factor this out into non_fatal_unexpected or something.
2592 let actual = self.this_token_to_string();
2593 self.span_err(self.span, &format!("unexpected token: `{}`", actual));
2598 if self.expr_is_complete(&e) { break; }
2601 token::OpenDelim(token::Paren) => {
2602 let seq = self.parse_unspanned_seq(
2603 &token::OpenDelim(token::Paren),
2604 &token::CloseDelim(token::Paren),
2605 SeqSep::trailing_allowed(token::Comma),
2606 |p| Ok(p.parse_expr()?)
2608 let nd = self.mk_call(e, es);
2609 let hi = self.prev_span;
2610 self.mk_expr(lo.to(hi), nd, ThinVec::new())
2612 e = self.recover_seq_parse_error(token::Paren, lo, seq);
2616 // Could be either an index expression or a slicing expression.
2617 token::OpenDelim(token::Bracket) => {
2619 let ix = self.parse_expr()?;
2621 self.expect(&token::CloseDelim(token::Bracket))?;
2622 let index = self.mk_index(e, ix);
2623 e = self.mk_expr(lo.to(hi), index, ThinVec::new())
2631 crate fn process_potential_macro_variable(&mut self) {
2632 let (token, span) = match self.token {
2633 token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
2634 self.look_ahead(1, |t| t.is_ident()) => {
2636 let name = match self.token {
2637 token::Ident(ident, _) => ident,
2640 let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
2641 err.span_label(self.span, "unknown macro variable");
2646 token::Interpolated(ref nt) => {
2647 self.meta_var_span = Some(self.span);
2648 // Interpolated identifier and lifetime tokens are replaced with usual identifier
2649 // and lifetime tokens, so the former are never encountered during normal parsing.
2651 token::NtIdent(ident, is_raw) => (token::Ident(ident, is_raw), ident.span),
2652 token::NtLifetime(ident) => (token::Lifetime(ident), ident.span),
2662 /// Parses a single token tree from the input.
2663 crate fn parse_token_tree(&mut self) -> TokenTree {
2665 token::OpenDelim(..) => {
2666 let frame = mem::replace(&mut self.token_cursor.frame,
2667 self.token_cursor.stack.pop().unwrap());
2668 self.span = frame.span.entire();
2670 TokenTree::Delimited(
2673 frame.tree_cursor.stream.into(),
2676 token::CloseDelim(_) | token::Eof => unreachable!(),
2678 let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span);
2680 TokenTree::Token(span, token)
2685 // parse a stream of tokens into a list of TokenTree's,
2687 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
2688 let mut tts = Vec::new();
2689 while self.token != token::Eof {
2690 tts.push(self.parse_token_tree());
2695 pub fn parse_tokens(&mut self) -> TokenStream {
2696 let mut result = Vec::new();
2699 token::Eof | token::CloseDelim(..) => break,
2700 _ => result.push(self.parse_token_tree().into()),
2703 TokenStream::new(result)
2706 /// Parse a prefix-unary-operator expr
2707 fn parse_prefix_expr(&mut self,
2708 already_parsed_attrs: Option<ThinVec<Attribute>>)
2709 -> PResult<'a, P<Expr>> {
2710 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
2712 // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2713 let (hi, ex) = match self.token {
2716 let e = self.parse_prefix_expr(None);
2717 let (span, e) = self.interpolated_or_expr_span(e)?;
2718 (lo.to(span), self.mk_unary(UnOp::Not, e))
2720 // Suggest `!` for bitwise negation when encountering a `~`
2723 let e = self.parse_prefix_expr(None);
2724 let (span, e) = self.interpolated_or_expr_span(e)?;
2725 let span_of_tilde = lo;
2726 let mut err = self.diagnostic()
2727 .struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator");
2728 err.span_suggestion_short(
2730 "use `!` to perform bitwise negation",
2732 Applicability::MachineApplicable
2735 (lo.to(span), self.mk_unary(UnOp::Not, e))
2737 token::BinOp(token::Minus) => {
2739 let e = self.parse_prefix_expr(None);
2740 let (span, e) = self.interpolated_or_expr_span(e)?;
2741 (lo.to(span), self.mk_unary(UnOp::Neg, e))
2743 token::BinOp(token::Star) => {
2745 let e = self.parse_prefix_expr(None);
2746 let (span, e) = self.interpolated_or_expr_span(e)?;
2747 (lo.to(span), self.mk_unary(UnOp::Deref, e))
2749 token::BinOp(token::And) | token::AndAnd => {
2751 let m = self.parse_mutability();
2752 let e = self.parse_prefix_expr(None);
2753 let (span, e) = self.interpolated_or_expr_span(e)?;
2754 (lo.to(span), ExprKind::AddrOf(m, e))
2756 token::Ident(..) if self.token.is_keyword(kw::Box) => {
2758 let e = self.parse_prefix_expr(None);
2759 let (span, e) = self.interpolated_or_expr_span(e)?;
2760 (lo.to(span), ExprKind::Box(e))
2762 token::Ident(..) if self.token.is_ident_named(sym::not) => {
2763 // `not` is just an ordinary identifier in Rust-the-language,
2764 // but as `rustc`-the-compiler, we can issue clever diagnostics
2765 // for confused users who really want to say `!`
2766 let token_cannot_continue_expr = |t: &token::Token| match *t {
2767 // These tokens can start an expression after `!`, but
2768 // can't continue an expression after an ident
2769 token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw),
2770 token::Literal(..) | token::Pound => true,
2771 token::Interpolated(ref nt) => match **nt {
2772 token::NtIdent(..) | token::NtExpr(..) |
2773 token::NtBlock(..) | token::NtPath(..) => true,
2778 let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
2779 if cannot_continue_expr {
2781 // Emit the error ...
2782 let mut err = self.diagnostic()
2783 .struct_span_err(self.span,
2784 &format!("unexpected {} after identifier",
2785 self.this_token_descr()));
2786 // span the `not` plus trailing whitespace to avoid
2787 // trailing whitespace after the `!` in our suggestion
2788 let to_replace = self.sess.source_map()
2789 .span_until_non_whitespace(lo.to(self.span));
2790 err.span_suggestion_short(
2792 "use `!` to perform logical negation",
2794 Applicability::MachineApplicable
2797 // —and recover! (just as if we were in the block
2798 // for the `token::Not` arm)
2799 let e = self.parse_prefix_expr(None);
2800 let (span, e) = self.interpolated_or_expr_span(e)?;
2801 (lo.to(span), self.mk_unary(UnOp::Not, e))
2803 return self.parse_dot_or_call_expr(Some(attrs));
2806 _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
2808 return Ok(self.mk_expr(lo.to(hi), ex, attrs));
2811 /// Parses an associative expression.
2813 /// This parses an expression accounting for associativity and precedence of the operators in
2816 fn parse_assoc_expr(&mut self,
2817 already_parsed_attrs: Option<ThinVec<Attribute>>)
2818 -> PResult<'a, P<Expr>> {
2819 self.parse_assoc_expr_with(0, already_parsed_attrs.into())
2822 /// Parses an associative expression with operators of at least `min_prec` precedence.
2823 fn parse_assoc_expr_with(&mut self,
2826 -> PResult<'a, P<Expr>> {
2827 let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
2830 let attrs = match lhs {
2831 LhsExpr::AttributesParsed(attrs) => Some(attrs),
2834 if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token) {
2835 return self.parse_prefix_range_expr(attrs);
2837 self.parse_prefix_expr(attrs)?
2841 match (self.expr_is_complete(&lhs), AssocOp::from_token(&self.token)) {
2843 // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
2846 (false, _) => {} // continue parsing the expression
2847 // An exhaustive check is done in the following block, but these are checked first
2848 // because they *are* ambiguous but also reasonable looking incorrect syntax, so we
2849 // want to keep their span info to improve diagnostics in these cases in a later stage.
2850 (true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;` or `{ 42 } * 3`
2851 (true, Some(AssocOp::Subtract)) | // `{ 42 } -5`
2852 (true, Some(AssocOp::Add)) => { // `{ 42 } + 42
2853 // These cases are ambiguous and can't be identified in the parser alone
2854 let sp = self.sess.source_map().start_point(self.span);
2855 self.sess.ambiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span);
2858 (true, Some(ref op)) if !op.can_continue_expr_unambiguously() => {
2861 (true, Some(_)) => {
2862 // We've found an expression that would be parsed as a statement, but the next
2863 // token implies this should be parsed as an expression.
2864 // For example: `if let Some(x) = x { x } else { 0 } / 2`
2865 let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &format!(
2866 "expected expression, found `{}`",
2867 pprust::token_to_string(&self.token),
2869 err.span_label(self.span, "expected expression");
2870 self.sess.expr_parentheses_needed(
2873 Some(pprust::expr_to_string(&lhs),
2878 self.expected_tokens.push(TokenType::Operator);
2879 while let Some(op) = AssocOp::from_token(&self.token) {
2881 // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
2882 // it refers to. Interpolated identifiers are unwrapped early and never show up here
2883 // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
2884 // it as "interpolated", it doesn't change the answer for non-interpolated idents.
2885 let lhs_span = match (self.prev_token_kind, &lhs.node) {
2886 (PrevTokenKind::Interpolated, _) => self.prev_span,
2887 (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
2888 if path.segments.len() == 1 => self.prev_span,
2892 let cur_op_span = self.span;
2893 let restrictions = if op.is_assign_like() {
2894 self.restrictions & Restrictions::NO_STRUCT_LITERAL
2898 let prec = op.precedence();
2899 if prec < min_prec {
2902 // Check for deprecated `...` syntax
2903 if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
2904 self.err_dotdotdot_syntax(self.span);
2908 if op.is_comparison() {
2909 self.check_no_chained_comparison(&lhs, &op);
2912 if op == AssocOp::As {
2913 lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
2915 } else if op == AssocOp::Colon {
2916 let maybe_path = self.could_ascription_be_path(&lhs.node);
2917 let next_sp = self.span;
2919 lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) {
2922 self.bad_type_ascription(
2933 } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
2934 // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
2935 // generalise it to the Fixity::None code.
2937 // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
2938 // two variants are handled with `parse_prefix_range_expr` call above.
2939 let rhs = if self.is_at_start_of_range_notation_rhs() {
2940 Some(self.parse_assoc_expr_with(prec + 1, LhsExpr::NotYetParsed)?)
2944 let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
2949 let limits = if op == AssocOp::DotDot {
2950 RangeLimits::HalfOpen
2955 let r = self.mk_range(Some(lhs), rhs, limits)?;
2956 lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
2960 let fixity = op.fixity();
2961 let prec_adjustment = match fixity {
2964 // We currently have no non-associative operators that are not handled above by
2965 // the special cases. The code is here only for future convenience.
2968 let rhs = self.with_res(
2969 restrictions - Restrictions::STMT_EXPR,
2970 |this| this.parse_assoc_expr_with(prec + prec_adjustment, LhsExpr::NotYetParsed)
2973 // Make sure that the span of the parent node is larger than the span of lhs and rhs,
2974 // including the attributes.
2978 .filter(|a| a.style == AttrStyle::Outer)
2980 .map_or(lhs_span, |a| a.span);
2981 let span = lhs_span.to(rhs.span);
2983 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
2984 AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
2985 AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
2986 AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
2987 AssocOp::Greater | AssocOp::GreaterEqual => {
2988 let ast_op = op.to_ast_binop().unwrap();
2989 let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
2990 self.mk_expr(span, binary, ThinVec::new())
2992 AssocOp::Assign => self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
2993 AssocOp::AssignOp(k) => {
2995 token::Plus => BinOpKind::Add,
2996 token::Minus => BinOpKind::Sub,
2997 token::Star => BinOpKind::Mul,
2998 token::Slash => BinOpKind::Div,
2999 token::Percent => BinOpKind::Rem,
3000 token::Caret => BinOpKind::BitXor,
3001 token::And => BinOpKind::BitAnd,
3002 token::Or => BinOpKind::BitOr,
3003 token::Shl => BinOpKind::Shl,
3004 token::Shr => BinOpKind::Shr,
3006 let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
3007 self.mk_expr(span, aopexpr, ThinVec::new())
3009 AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
3010 self.bug("AssocOp should have been handled by special case")
3014 if let Fixity::None = fixity { break }
3019 fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
3020 expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
3021 -> PResult<'a, P<Expr>> {
3022 let mk_expr = |this: &mut Self, rhs: P<Ty>| {
3023 this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
3026 // Save the state of the parser before parsing type normally, in case there is a
3027 // LessThan comparison after this cast.
3028 let parser_snapshot_before_type = self.clone();
3029 match self.parse_ty_no_plus() {
3031 Ok(mk_expr(self, rhs))
3033 Err(mut type_err) => {
3034 // Rewind to before attempting to parse the type with generics, to recover
3035 // from situations like `x as usize < y` in which we first tried to parse
3036 // `usize < y` as a type with generic arguments.
3037 let parser_snapshot_after_type = self.clone();
3038 mem::replace(self, parser_snapshot_before_type);
3040 match self.parse_path(PathStyle::Expr) {
3042 let (op_noun, op_verb) = match self.token {
3043 token::Lt => ("comparison", "comparing"),
3044 token::BinOp(token::Shl) => ("shift", "shifting"),
3046 // We can end up here even without `<` being the next token, for
3047 // example because `parse_ty_no_plus` returns `Err` on keywords,
3048 // but `parse_path` returns `Ok` on them due to error recovery.
3049 // Return original error and parser state.
3050 mem::replace(self, parser_snapshot_after_type);
3051 return Err(type_err);
3055 // Successfully parsed the type path leaving a `<` yet to parse.
3058 // Report non-fatal diagnostics, keep `x as usize` as an expression
3059 // in AST and continue parsing.
3060 let msg = format!("`<` is interpreted as a start of generic \
3061 arguments for `{}`, not a {}", path, op_noun);
3062 let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
3063 err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span),
3064 "interpreted as generic arguments");
3065 err.span_label(self.span, format!("not interpreted as {}", op_noun));
3067 let expr = mk_expr(self, P(Ty {
3069 node: TyKind::Path(None, path),
3070 id: ast::DUMMY_NODE_ID
3073 let expr_str = self.sess.source_map().span_to_snippet(expr.span)
3074 .unwrap_or_else(|_| pprust::expr_to_string(&expr));
3075 err.span_suggestion(
3077 &format!("try {} the cast value", op_verb),
3078 format!("({})", expr_str),
3079 Applicability::MachineApplicable
3085 Err(mut path_err) => {
3086 // Couldn't parse as a path, return original error and parser state.
3088 mem::replace(self, parser_snapshot_after_type);
3096 /// Parse prefix-forms of range notation: `..expr`, `..`, `..=expr`
3097 fn parse_prefix_range_expr(&mut self,
3098 already_parsed_attrs: Option<ThinVec<Attribute>>)
3099 -> PResult<'a, P<Expr>> {
3100 // Check for deprecated `...` syntax
3101 if self.token == token::DotDotDot {
3102 self.err_dotdotdot_syntax(self.span);
3105 debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token),
3106 "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
3108 let tok = self.token.clone();
3109 let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
3111 let mut hi = self.span;
3113 let opt_end = if self.is_at_start_of_range_notation_rhs() {
3114 // RHS must be parsed with more associativity than the dots.
3115 let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
3116 Some(self.parse_assoc_expr_with(next_prec,
3117 LhsExpr::NotYetParsed)
3125 let limits = if tok == token::DotDot {
3126 RangeLimits::HalfOpen
3131 let r = self.mk_range(None, opt_end, limits)?;
3132 Ok(self.mk_expr(lo.to(hi), r, attrs))
3135 fn is_at_start_of_range_notation_rhs(&self) -> bool {
3136 if self.token.can_begin_expr() {
3137 // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
3138 if self.token == token::OpenDelim(token::Brace) {
3139 return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
3147 /// Parses an `if` or `if let` expression (`if` token already eaten).
3148 fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3149 if self.check_keyword(kw::Let) {
3150 return self.parse_if_let_expr(attrs);
3152 let lo = self.prev_span;
3153 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3155 // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
3156 // verify that the last statement is either an implicit return (no `;`) or an explicit
3157 // return. This won't catch blocks with an explicit `return`, but that would be caught by
3158 // the dead code lint.
3159 if self.eat_keyword(kw::Else) || !cond.returns() {
3160 let sp = self.sess.source_map().next_point(lo);
3161 let mut err = self.diagnostic()
3162 .struct_span_err(sp, "missing condition for `if` statemement");
3163 err.span_label(sp, "expected if condition here");
3166 let not_block = self.token != token::OpenDelim(token::Brace);
3167 let thn = self.parse_block().map_err(|mut err| {
3169 err.span_label(lo, "this `if` statement has a condition, but no block");
3173 let mut els: Option<P<Expr>> = None;
3174 let mut hi = thn.span;
3175 if self.eat_keyword(kw::Else) {
3176 let elexpr = self.parse_else_expr()?;
3180 Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
3183 /// Parses an `if let` expression (`if` token already eaten).
3184 fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
3185 -> PResult<'a, P<Expr>> {
3186 let lo = self.prev_span;
3187 self.expect_keyword(kw::Let)?;
3188 let pats = self.parse_pats()?;
3189 self.expect(&token::Eq)?;
3190 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3191 let thn = self.parse_block()?;
3192 let (hi, els) = if self.eat_keyword(kw::Else) {
3193 let expr = self.parse_else_expr()?;
3194 (expr.span, Some(expr))
3198 Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
3201 /// Parses `move |args| expr`.
3202 fn parse_lambda_expr(&mut self,
3203 attrs: ThinVec<Attribute>)
3204 -> PResult<'a, P<Expr>>
3207 let movability = if self.eat_keyword(kw::Static) {
3212 let asyncness = if self.span.rust_2018() {
3213 self.parse_asyncness()
3217 let capture_clause = if self.eat_keyword(kw::Move) {
3222 let decl = self.parse_fn_block_decl()?;
3223 let decl_hi = self.prev_span;
3224 let body = match decl.output {
3225 FunctionRetTy::Default(_) => {
3226 let restrictions = self.restrictions - Restrictions::STMT_EXPR;
3227 self.parse_expr_res(restrictions, None)?
3230 // If an explicit return type is given, require a
3231 // block to appear (RFC 968).
3232 let body_lo = self.span;
3233 self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
3239 ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
3243 // `else` token already eaten
3244 fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
3245 if self.eat_keyword(kw::If) {
3246 return self.parse_if_expr(ThinVec::new());
3248 let blk = self.parse_block()?;
3249 return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
3253 /// Parse a 'for' .. 'in' expression ('for' token already eaten)
3254 fn parse_for_expr(&mut self, opt_label: Option<Label>,
3256 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3257 // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
3259 let pat = self.parse_top_level_pat()?;
3260 if !self.eat_keyword(kw::In) {
3261 let in_span = self.prev_span.between(self.span);
3262 let mut err = self.sess.span_diagnostic
3263 .struct_span_err(in_span, "missing `in` in `for` loop");
3264 err.span_suggestion_short(
3265 in_span, "try adding `in` here", " in ".into(),
3266 // has been misleading, at least in the past (closed Issue #48492)
3267 Applicability::MaybeIncorrect
3271 let in_span = self.prev_span;
3272 self.check_for_for_in_in_typo(in_span);
3273 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3274 let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
3275 attrs.extend(iattrs);
3277 let hi = self.prev_span;
3278 Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
3281 /// Parses a `while` or `while let` expression (`while` token already eaten).
3282 fn parse_while_expr(&mut self, opt_label: Option<Label>,
3284 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3285 if self.token.is_keyword(kw::Let) {
3286 return self.parse_while_let_expr(opt_label, span_lo, attrs);
3288 let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3289 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3290 attrs.extend(iattrs);
3291 let span = span_lo.to(body.span);
3292 return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs));
3295 /// Parses a `while let` expression (`while` token already eaten).
3296 fn parse_while_let_expr(&mut self, opt_label: Option<Label>,
3298 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3299 self.expect_keyword(kw::Let)?;
3300 let pats = self.parse_pats()?;
3301 self.expect(&token::Eq)?;
3302 let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
3303 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3304 attrs.extend(iattrs);
3305 let span = span_lo.to(body.span);
3306 return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
3309 // parse `loop {...}`, `loop` token already eaten
3310 fn parse_loop_expr(&mut self, opt_label: Option<Label>,
3312 mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3313 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3314 attrs.extend(iattrs);
3315 let span = span_lo.to(body.span);
3316 Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
3319 /// Parses an `async move {...}` expression.
3320 pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>)
3321 -> PResult<'a, P<Expr>>
3323 let span_lo = self.span;
3324 self.expect_keyword(kw::Async)?;
3325 let capture_clause = if self.eat_keyword(kw::Move) {
3330 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3331 attrs.extend(iattrs);
3333 span_lo.to(body.span),
3334 ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs))
3337 /// Parses a `try {...}` expression (`try` token already eaten).
3338 fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
3339 -> PResult<'a, P<Expr>>
3341 let (iattrs, body) = self.parse_inner_attrs_and_block()?;
3342 attrs.extend(iattrs);
3343 if self.eat_keyword(kw::Catch) {
3344 let mut error = self.struct_span_err(self.prev_span,
3345 "keyword `catch` cannot follow a `try` block");
3346 error.help("try using `match` on the result of the `try` block instead");
3350 Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
3354 // `match` token already eaten
3355 fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
3356 let match_span = self.prev_span;
3357 let lo = self.prev_span;
3358 let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL,
3360 if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
3361 if self.token == token::Token::Semi {
3362 e.span_suggestion_short(
3364 "try removing this `match`",
3366 Applicability::MaybeIncorrect // speculative
3371 attrs.extend(self.parse_inner_attributes()?);
3373 let mut arms: Vec<Arm> = Vec::new();
3374 while self.token != token::CloseDelim(token::Brace) {
3375 match self.parse_arm() {
3376 Ok(arm) => arms.push(arm),
3378 // Recover by skipping to the end of the block.
3380 self.recover_stmt();
3381 let span = lo.to(self.span);
3382 if self.token == token::CloseDelim(token::Brace) {
3385 return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
3391 return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
3394 crate fn parse_arm(&mut self) -> PResult<'a, Arm> {
3395 let attrs = self.parse_outer_attributes()?;
3397 let pats = self.parse_pats()?;
3398 let guard = if self.eat_keyword(kw::If) {
3399 Some(Guard::If(self.parse_expr()?))
3403 let arrow_span = self.span;
3404 self.expect(&token::FatArrow)?;
3405 let arm_start_span = self.span;
3407 let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
3408 .map_err(|mut err| {
3409 err.span_label(arrow_span, "while parsing the `match` arm starting here");
3413 let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
3414 && self.token != token::CloseDelim(token::Brace);
3419 let cm = self.sess.source_map();
3420 self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
3421 .map_err(|mut err| {
3422 match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
3423 (Ok(ref expr_lines), Ok(ref arm_start_lines))
3424 if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
3425 && expr_lines.lines.len() == 2
3426 && self.token == token::FatArrow => {
3427 // We check whether there's any trailing code in the parse span,
3428 // if there isn't, we very likely have the following:
3431 // | -- - missing comma
3437 // | parsed until here as `"y" & X`
3438 err.span_suggestion_short(
3439 cm.next_point(arm_start_span),
3440 "missing a comma here to end this `match` arm",
3442 Applicability::MachineApplicable
3446 err.span_label(arrow_span,
3447 "while parsing the `match` arm starting here");
3453 self.eat(&token::Comma);
3465 /// Parses an expression.
3467 pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
3468 self.parse_expr_res(Restrictions::empty(), None)
3471 /// Evaluates the closure with restrictions in place.
3473 /// Afters the closure is evaluated, restrictions are reset.
3474 fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T
3475 where F: FnOnce(&mut Self) -> T
3477 let old = self.restrictions;
3478 self.restrictions = r;
3480 self.restrictions = old;
3485 /// Parses an expression, subject to the given restrictions.
3487 fn parse_expr_res(&mut self, r: Restrictions,
3488 already_parsed_attrs: Option<ThinVec<Attribute>>)
3489 -> PResult<'a, P<Expr>> {
3490 self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
3493 /// Parses the RHS of a local variable declaration (e.g., '= 14;').
3494 fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
3495 if self.eat(&token::Eq) {
3496 Ok(Some(self.parse_expr()?))
3498 Ok(Some(self.parse_expr()?))
3504 /// Parses patterns, separated by '|' s.
3505 fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3506 // Allow a '|' before the pats (RFC 1925 + RFC 2530)
3507 self.eat(&token::BinOp(token::Or));
3509 let mut pats = Vec::new();
3511 pats.push(self.parse_top_level_pat()?);
3513 if self.token == token::OrOr {
3514 let mut err = self.struct_span_err(self.span,
3515 "unexpected token `||` after pattern");
3516 err.span_suggestion(
3518 "use a single `|` to specify multiple patterns",
3520 Applicability::MachineApplicable
3524 } else if self.eat(&token::BinOp(token::Or)) {
3525 // This is a No-op. Continue the loop to parse the next
3533 // Parses a parenthesized list of patterns like
3534 // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns:
3535 // - a vector of the patterns that were parsed
3536 // - an option indicating the index of the `..` element
3537 // - a boolean indicating whether a trailing comma was present.
3538 // Trailing commas are significant because (p) and (p,) are different patterns.
3539 fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3540 self.expect(&token::OpenDelim(token::Paren))?;
3541 let result = match self.parse_pat_list() {
3542 Ok(result) => result,
3543 Err(mut err) => { // recover from parse error in tuple pattern list
3545 self.consume_block(token::Paren);
3546 return Ok((vec![], Some(0), false));
3549 self.expect(&token::CloseDelim(token::Paren))?;
3553 fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
3554 let mut fields = Vec::new();
3555 let mut ddpos = None;
3556 let mut prev_dd_sp = None;
3557 let mut trailing_comma = false;
3559 if self.eat(&token::DotDot) {
3560 if ddpos.is_none() {
3561 ddpos = Some(fields.len());
3562 prev_dd_sp = Some(self.prev_span);
3564 // Emit a friendly error, ignore `..` and continue parsing
3565 let mut err = self.struct_span_err(
3567 "`..` can only be used once per tuple or tuple struct pattern",
3569 err.span_label(self.prev_span, "can only be used once per pattern");
3570 if let Some(sp) = prev_dd_sp {
3571 err.span_label(sp, "previously present here");
3575 } else if !self.check(&token::CloseDelim(token::Paren)) {
3576 fields.push(self.parse_pat(None)?);
3581 trailing_comma = self.eat(&token::Comma);
3582 if !trailing_comma {
3587 if ddpos == Some(fields.len()) && trailing_comma {
3588 // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
3589 let msg = "trailing comma is not permitted after `..`";
3590 self.struct_span_err(self.prev_span, msg)
3591 .span_label(self.prev_span, msg)
3595 Ok((fields, ddpos, trailing_comma))
3598 fn parse_pat_vec_elements(
3600 ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3601 let mut before = Vec::new();
3602 let mut slice = None;
3603 let mut after = Vec::new();
3604 let mut first = true;
3605 let mut before_slice = true;
3607 while self.token != token::CloseDelim(token::Bracket) {
3611 self.expect(&token::Comma)?;
3613 if self.token == token::CloseDelim(token::Bracket)
3614 && (before_slice || !after.is_empty()) {
3620 if self.eat(&token::DotDot) {
3622 if self.check(&token::Comma) ||
3623 self.check(&token::CloseDelim(token::Bracket)) {
3624 slice = Some(P(Pat {
3625 id: ast::DUMMY_NODE_ID,
3626 node: PatKind::Wild,
3627 span: self.prev_span,
3629 before_slice = false;
3635 let subpat = self.parse_pat(None)?;
3636 if before_slice && self.eat(&token::DotDot) {
3637 slice = Some(subpat);
3638 before_slice = false;
3639 } else if before_slice {
3640 before.push(subpat);
3646 Ok((before, slice, after))
3652 attrs: Vec<Attribute>
3653 ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> {
3654 // Check if a colon exists one ahead. This means we're parsing a fieldname.
3656 let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3657 // Parsing a pattern of the form "fieldname: pat"
3658 let fieldname = self.parse_field_name()?;
3660 let pat = self.parse_pat(None)?;
3662 (pat, fieldname, false)
3664 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3665 let is_box = self.eat_keyword(kw::Box);
3666 let boxed_span = self.span;
3667 let is_ref = self.eat_keyword(kw::Ref);
3668 let is_mut = self.eat_keyword(kw::Mut);
3669 let fieldname = self.parse_ident()?;
3670 hi = self.prev_span;
3672 let bind_type = match (is_ref, is_mut) {
3673 (true, true) => BindingMode::ByRef(Mutability::Mutable),
3674 (true, false) => BindingMode::ByRef(Mutability::Immutable),
3675 (false, true) => BindingMode::ByValue(Mutability::Mutable),
3676 (false, false) => BindingMode::ByValue(Mutability::Immutable),
3678 let fieldpat = P(Pat {
3679 id: ast::DUMMY_NODE_ID,
3680 node: PatKind::Ident(bind_type, fieldname, None),
3681 span: boxed_span.to(hi),
3684 let subpat = if is_box {
3686 id: ast::DUMMY_NODE_ID,
3687 node: PatKind::Box(fieldpat),
3693 (subpat, fieldname, true)
3696 Ok(source_map::Spanned {
3698 node: ast::FieldPat {
3702 attrs: attrs.into(),
3707 /// Parses the fields of a struct-like pattern.
3708 fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> {
3709 let mut fields = Vec::new();
3710 let mut etc = false;
3711 let mut ate_comma = true;
3712 let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
3713 let mut etc_span = None;
3715 while self.token != token::CloseDelim(token::Brace) {
3716 let attrs = self.parse_outer_attributes()?;
3719 // check that a comma comes after every field
3721 let err = self.struct_span_err(self.prev_span, "expected `,`");
3722 if let Some(mut delayed) = delayed_err {
3729 if self.check(&token::DotDot) || self.token == token::DotDotDot {
3731 let mut etc_sp = self.span;
3733 if self.token == token::DotDotDot { // Issue #46718
3734 // Accept `...` as if it were `..` to avoid further errors
3735 let mut err = self.struct_span_err(self.span,
3736 "expected field pattern, found `...`");
3737 err.span_suggestion(
3739 "to omit remaining fields, use one fewer `.`",
3741 Applicability::MachineApplicable
3745 self.bump(); // `..` || `...`
3747 if self.token == token::CloseDelim(token::Brace) {
3748 etc_span = Some(etc_sp);
3751 let token_str = self.this_token_descr();
3752 let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
3754 err.span_label(self.span, "expected `}`");
3755 let mut comma_sp = None;
3756 if self.token == token::Comma { // Issue #49257
3757 etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span));
3758 err.span_label(etc_sp,
3759 "`..` must be at the end and cannot have a trailing comma");
3760 comma_sp = Some(self.span);
3765 etc_span = Some(etc_sp.until(self.span));
3766 if self.token == token::CloseDelim(token::Brace) {
3767 // If the struct looks otherwise well formed, recover and continue.
3768 if let Some(sp) = comma_sp {
3769 err.span_suggestion_short(
3771 "remove this comma",
3773 Applicability::MachineApplicable,
3778 } else if self.token.is_ident() && ate_comma {
3779 // Accept fields coming after `..,`.
3780 // This way we avoid "pattern missing fields" errors afterwards.
3781 // We delay this error until the end in order to have a span for a
3783 if let Some(mut delayed_err) = delayed_err {
3787 delayed_err = Some(err);
3790 if let Some(mut err) = delayed_err {
3797 fields.push(match self.parse_pat_field(lo, attrs) {
3800 if let Some(mut delayed_err) = delayed_err {
3806 ate_comma = self.eat(&token::Comma);
3809 if let Some(mut err) = delayed_err {
3810 if let Some(etc_span) = etc_span {
3811 err.multipart_suggestion(
3812 "move the `..` to the end of the field list",
3814 (etc_span, String::new()),
3815 (self.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
3817 Applicability::MachineApplicable,
3822 return Ok((fields, etc));
3825 fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
3826 if self.token.is_path_start() {
3828 let (qself, path) = if self.eat_lt() {
3829 // Parse a qualified path
3830 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
3833 // Parse an unqualified path
3834 (None, self.parse_path(PathStyle::Expr)?)
3836 let hi = self.prev_span;
3837 Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
3839 self.parse_literal_maybe_minus()
3843 // helper function to decide whether to parse as ident binding or to try to do
3844 // something more complex like range patterns
3845 fn parse_as_ident(&mut self) -> bool {
3846 self.look_ahead(1, |t| match *t {
3847 token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
3848 token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false),
3849 // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the
3850 // range pattern branch
3851 token::DotDot => None,
3853 }).unwrap_or_else(|| self.look_ahead(2, |t| match *t {
3854 token::Comma | token::CloseDelim(token::Bracket) => true,
3859 /// A wrapper around `parse_pat` with some special error handling for the
3860 /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
3861 /// to subpatterns within such).
3862 fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
3863 let pat = self.parse_pat(None)?;
3864 if self.token == token::Comma {
3865 // An unexpected comma after a top-level pattern is a clue that the
3866 // user (perhaps more accustomed to some other language) forgot the
3867 // parentheses in what should have been a tuple pattern; return a
3868 // suggestion-enhanced error here rather than choking on the comma
3870 let comma_span = self.span;
3872 if let Err(mut err) = self.parse_pat_list() {
3873 // We didn't expect this to work anyway; we just wanted
3874 // to advance to the end of the comma-sequence so we know
3875 // the span to suggest parenthesizing
3878 let seq_span = pat.span.to(self.prev_span);
3879 let mut err = self.struct_span_err(comma_span,
3880 "unexpected `,` in pattern");
3881 if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) {
3882 err.span_suggestion(
3884 "try adding parentheses to match on a tuple..",
3885 format!("({})", seq_snippet),
3886 Applicability::MachineApplicable
3889 "..or a vertical bar to match on multiple alternatives",
3890 format!("{}", seq_snippet.replace(",", " |")),
3891 Applicability::MachineApplicable
3899 /// Parses a pattern.
3900 pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
3901 self.parse_pat_with_range_pat(true, expected)
3904 /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
3906 fn parse_pat_with_range_pat(
3908 allow_range_pat: bool,
3909 expected: Option<&'static str>,
3910 ) -> PResult<'a, P<Pat>> {
3911 maybe_recover_from_interpolated_ty_qpath!(self, true);
3912 maybe_whole!(self, NtPat, |x| x);
3917 token::BinOp(token::And) | token::AndAnd => {
3918 // Parse &pat / &mut pat
3920 let mutbl = self.parse_mutability();
3921 if let token::Lifetime(ident) = self.token {
3922 let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern",
3924 err.span_label(self.span, "unexpected lifetime");
3927 let subpat = self.parse_pat_with_range_pat(false, expected)?;
3928 pat = PatKind::Ref(subpat, mutbl);
3930 token::OpenDelim(token::Paren) => {
3931 // Parse (pat,pat,pat,...) as tuple pattern
3932 let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?;
3933 pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma {
3934 PatKind::Paren(fields.into_iter().nth(0).unwrap())
3936 PatKind::Tuple(fields, ddpos)
3939 token::OpenDelim(token::Bracket) => {
3940 // Parse [pat,pat,...] as slice pattern
3942 let (before, slice, after) = self.parse_pat_vec_elements()?;
3943 self.expect(&token::CloseDelim(token::Bracket))?;
3944 pat = PatKind::Slice(before, slice, after);
3946 // At this point, token != &, &&, (, [
3947 _ => if self.eat_keyword(kw::Underscore) {
3949 pat = PatKind::Wild;
3950 } else if self.eat_keyword(kw::Mut) {
3951 // Parse mut ident @ pat / mut ref ident @ pat
3952 let mutref_span = self.prev_span.to(self.span);
3953 let binding_mode = if self.eat_keyword(kw::Ref) {
3955 .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
3958 "try switching the order",
3960 Applicability::MachineApplicable
3962 BindingMode::ByRef(Mutability::Mutable)
3964 BindingMode::ByValue(Mutability::Mutable)
3966 pat = self.parse_pat_ident(binding_mode)?;
3967 } else if self.eat_keyword(kw::Ref) {
3968 // Parse ref ident @ pat / ref mut ident @ pat
3969 let mutbl = self.parse_mutability();
3970 pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
3971 } else if self.eat_keyword(kw::Box) {
3973 let subpat = self.parse_pat_with_range_pat(false, None)?;
3974 pat = PatKind::Box(subpat);
3975 } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
3976 self.parse_as_ident() {
3977 // Parse ident @ pat
3978 // This can give false positives and parse nullary enums,
3979 // they are dealt with later in resolve
3980 let binding_mode = BindingMode::ByValue(Mutability::Immutable);
3981 pat = self.parse_pat_ident(binding_mode)?;
3982 } else if self.token.is_path_start() {
3983 // Parse pattern starting with a path
3984 let (qself, path) = if self.eat_lt() {
3985 // Parse a qualified path
3986 let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
3989 // Parse an unqualified path
3990 (None, self.parse_path(PathStyle::Expr)?)
3993 token::Not if qself.is_none() => {
3994 // Parse macro invocation
3996 let (delim, tts) = self.expect_delimited_token_tree()?;
3997 let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim });
3998 pat = PatKind::Mac(mac);
4000 token::DotDotDot | token::DotDotEq | token::DotDot => {
4001 let end_kind = match self.token {
4002 token::DotDot => RangeEnd::Excluded,
4003 token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot),
4004 token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq),
4005 _ => panic!("can only parse `..`/`...`/`..=` for ranges \
4008 let op_span = self.span;
4010 let span = lo.to(self.prev_span);
4011 let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
4013 let end = self.parse_pat_range_end()?;
4014 let op = Spanned { span: op_span, node: end_kind };
4015 pat = PatKind::Range(begin, end, op);
4017 token::OpenDelim(token::Brace) => {
4018 if qself.is_some() {
4019 let msg = "unexpected `{` after qualified path";
4020 let mut err = self.fatal(msg);
4021 err.span_label(self.span, msg);
4024 // Parse struct pattern
4026 let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
4028 self.recover_stmt();
4032 pat = PatKind::Struct(path, fields, etc);
4034 token::OpenDelim(token::Paren) => {
4035 if qself.is_some() {
4036 let msg = "unexpected `(` after qualified path";
4037 let mut err = self.fatal(msg);
4038 err.span_label(self.span, msg);
4041 // Parse tuple struct or enum pattern
4042 let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?;
4043 pat = PatKind::TupleStruct(path, fields, ddpos)
4045 _ => pat = PatKind::Path(qself, path),
4048 // Try to parse everything else as literal with optional minus
4049 match self.parse_literal_maybe_minus() {
4051 let op_span = self.span;
4052 if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
4053 self.check(&token::DotDotDot) {
4054 let end_kind = if self.eat(&token::DotDotDot) {
4055 RangeEnd::Included(RangeSyntax::DotDotDot)
4056 } else if self.eat(&token::DotDotEq) {
4057 RangeEnd::Included(RangeSyntax::DotDotEq)
4058 } else if self.eat(&token::DotDot) {
4061 panic!("impossible case: we already matched \
4062 on a range-operator token")
4064 let end = self.parse_pat_range_end()?;
4065 let op = Spanned { span: op_span, node: end_kind };
4066 pat = PatKind::Range(begin, end, op);
4068 pat = PatKind::Lit(begin);
4072 self.cancel(&mut err);
4073 let expected = expected.unwrap_or("pattern");
4075 "expected {}, found {}",
4077 self.this_token_descr(),
4079 let mut err = self.fatal(&msg);
4080 err.span_label(self.span, format!("expected {}", expected));
4081 let sp = self.sess.source_map().start_point(self.span);
4082 if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
4083 self.sess.expr_parentheses_needed(&mut err, *sp, None);
4091 let pat = P(Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID });
4092 let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
4094 if !allow_range_pat {
4097 _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
4099 PatKind::Range(..) => {
4100 let mut err = self.struct_span_err(
4102 "the range pattern here has ambiguous interpretation",
4104 err.span_suggestion(
4106 "add parentheses to clarify the precedence",
4107 format!("({})", pprust::pat_to_string(&pat)),
4108 // "ambiguous interpretation" implies that we have to be guessing
4109 Applicability::MaybeIncorrect
4120 /// Parses `ident` or `ident @ pat`.
4121 /// used by the copy foo and ref foo patterns to give a good
4122 /// error message when parsing mistakes like `ref foo(a, b)`.
4123 fn parse_pat_ident(&mut self,
4124 binding_mode: ast::BindingMode)
4125 -> PResult<'a, PatKind> {
4126 let ident = self.parse_ident()?;
4127 let sub = if self.eat(&token::At) {
4128 Some(self.parse_pat(Some("binding pattern"))?)
4133 // just to be friendly, if they write something like
4135 // we end up here with ( as the current token. This shortly
4136 // leads to a parse error. Note that if there is no explicit
4137 // binding mode then we do not end up here, because the lookahead
4138 // will direct us over to parse_enum_variant()
4139 if self.token == token::OpenDelim(token::Paren) {
4140 return Err(self.span_fatal(
4142 "expected identifier, found enum pattern"))
4145 Ok(PatKind::Ident(binding_mode, ident, sub))
4148 /// Parses a local variable declaration.
4149 fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
4150 let lo = self.prev_span;
4151 let pat = self.parse_top_level_pat()?;
4153 let (err, ty) = if self.eat(&token::Colon) {
4154 // Save the state of the parser before parsing type normally, in case there is a `:`
4155 // instead of an `=` typo.
4156 let parser_snapshot_before_type = self.clone();
4157 let colon_sp = self.prev_span;
4158 match self.parse_ty() {
4159 Ok(ty) => (None, Some(ty)),
4161 // Rewind to before attempting to parse the type and continue parsing
4162 let parser_snapshot_after_type = self.clone();
4163 mem::replace(self, parser_snapshot_before_type);
4165 let snippet = self.sess.source_map().span_to_snippet(pat.span).unwrap();
4166 err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
4167 (Some((parser_snapshot_after_type, colon_sp, err)), None)
4173 let init = match (self.parse_initializer(err.is_some()), err) {
4174 (Ok(init), None) => { // init parsed, ty parsed
4177 (Ok(init), Some((_, colon_sp, mut err))) => { // init parsed, ty error
4178 // Could parse the type as if it were the initializer, it is likely there was a
4179 // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
4180 err.span_suggestion_short(
4182 "use `=` if you meant to assign",
4184 Applicability::MachineApplicable
4187 // As this was parsed successfully, continue as if the code has been fixed for the
4188 // rest of the file. It will still fail due to the emitted error, but we avoid
4192 (Err(mut init_err), Some((snapshot, _, ty_err))) => { // init error, ty error
4194 // Couldn't parse the type nor the initializer, only raise the type error and
4195 // return to the parser state before parsing the type as the initializer.
4196 // let x: <parse_error>;
4197 mem::replace(self, snapshot);
4200 (Err(err), None) => { // init error, ty parsed
4201 // Couldn't parse the initializer and we're not attempting to recover a failed
4202 // parse of the type, return the error.
4206 let hi = if self.token == token::Semi {
4215 id: ast::DUMMY_NODE_ID,
4218 source: LocalSource::Normal,
4222 /// Parses a structure field.
4223 fn parse_name_and_ty(&mut self,
4226 attrs: Vec<Attribute>)
4227 -> PResult<'a, StructField> {
4228 let name = self.parse_ident()?;
4229 self.expect(&token::Colon)?;
4230 let ty = self.parse_ty()?;
4232 span: lo.to(self.prev_span),
4235 id: ast::DUMMY_NODE_ID,
4241 /// Emits an expected-item-after-attributes error.
4242 fn expected_item_err(&mut self, attrs: &[Attribute]) -> PResult<'a, ()> {
4243 let message = match attrs.last() {
4244 Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
4245 _ => "expected item after attributes",
4248 let mut err = self.diagnostic().struct_span_err(self.prev_span, message);
4249 if attrs.last().unwrap().is_sugared_doc {
4250 err.span_label(self.prev_span, "this doc comment doesn't document anything");
4255 /// Parse a statement. This stops just before trailing semicolons on everything but items.
4256 /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
4257 pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
4258 Ok(self.parse_stmt_(true))
4261 fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
4262 self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
4264 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4269 fn is_async_block(&self) -> bool {
4270 self.token.is_keyword(kw::Async) &&
4273 self.look_ahead(1, |t| t.is_keyword(kw::Move)) &&
4274 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
4276 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
4281 fn is_async_fn(&self) -> bool {
4282 self.token.is_keyword(kw::Async) &&
4283 self.look_ahead(1, |t| t.is_keyword(kw::Fn))
4286 fn is_do_catch_block(&self) -> bool {
4287 self.token.is_keyword(kw::Do) &&
4288 self.look_ahead(1, |t| t.is_keyword(kw::Catch)) &&
4289 self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
4290 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4293 fn is_try_block(&self) -> bool {
4294 self.token.is_keyword(kw::Try) &&
4295 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
4296 self.span.rust_2018() &&
4297 // prevent `while try {} {}`, `if try {} {} else {}`, etc.
4298 !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
4301 fn is_union_item(&self) -> bool {
4302 self.token.is_keyword(kw::Union) &&
4303 self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
4306 fn is_crate_vis(&self) -> bool {
4307 self.token.is_keyword(kw::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
4310 fn is_existential_type_decl(&self) -> bool {
4311 self.token.is_keyword(kw::Existential) &&
4312 self.look_ahead(1, |t| t.is_keyword(kw::Type))
4315 fn is_auto_trait_item(&self) -> bool {
4317 (self.token.is_keyword(kw::Auto)
4318 && self.look_ahead(1, |t| t.is_keyword(kw::Trait)))
4319 || // unsafe auto trait
4320 (self.token.is_keyword(kw::Unsafe) &&
4321 self.look_ahead(1, |t| t.is_keyword(kw::Auto)) &&
4322 self.look_ahead(2, |t| t.is_keyword(kw::Trait)))
4325 fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span)
4326 -> PResult<'a, Option<P<Item>>> {
4327 let token_lo = self.span;
4328 let (ident, def) = match self.token {
4329 token::Ident(ident, false) if ident.name == kw::Macro => {
4331 let ident = self.parse_ident()?;
4332 let tokens = if self.check(&token::OpenDelim(token::Brace)) {
4333 match self.parse_token_tree() {
4334 TokenTree::Delimited(_, _, tts) => tts,
4335 _ => unreachable!(),
4337 } else if self.check(&token::OpenDelim(token::Paren)) {
4338 let args = self.parse_token_tree();
4339 let body = if self.check(&token::OpenDelim(token::Brace)) {
4340 self.parse_token_tree()
4345 TokenStream::new(vec![
4347 TokenTree::Token(token_lo.to(self.prev_span), token::FatArrow).into(),
4355 (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
4357 token::Ident(ident, _) if ident.name == sym::macro_rules &&
4358 self.look_ahead(1, |t| *t == token::Not) => {
4359 let prev_span = self.prev_span;
4360 self.complain_if_pub_macro(&vis.node, prev_span);
4364 let ident = self.parse_ident()?;
4365 let (delim, tokens) = self.expect_delimited_token_tree()?;
4366 if delim != MacDelimiter::Brace && !self.eat(&token::Semi) {
4367 self.report_invalid_macro_expansion_item();
4370 (ident, ast::MacroDef { tokens: tokens, legacy: true })
4372 _ => return Ok(None),
4375 let span = lo.to(self.prev_span);
4376 Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
4379 fn parse_stmt_without_recovery(&mut self,
4380 macro_legacy_warnings: bool)
4381 -> PResult<'a, Option<Stmt>> {
4382 maybe_whole!(self, NtStmt, |x| Some(x));
4384 let attrs = self.parse_outer_attributes()?;
4387 Ok(Some(if self.eat_keyword(kw::Let) {
4389 id: ast::DUMMY_NODE_ID,
4390 node: StmtKind::Local(self.parse_local(attrs.into())?),
4391 span: lo.to(self.prev_span),
4393 } else if let Some(macro_def) = self.eat_macro_def(
4395 &source_map::respan(lo, VisibilityKind::Inherited),
4399 id: ast::DUMMY_NODE_ID,
4400 node: StmtKind::Item(macro_def),
4401 span: lo.to(self.prev_span),
4403 // Starts like a simple path, being careful to avoid contextual keywords
4404 // such as a union items, item with `crate` visibility or auto trait items.
4405 // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
4406 // like a path (1 token), but it fact not a path.
4407 // `union::b::c` - path, `union U { ... }` - not a path.
4408 // `crate::b::c` - path, `crate struct S;` - not a path.
4409 } else if self.token.is_path_start() &&
4410 !self.token.is_qpath_start() &&
4411 !self.is_union_item() &&
4412 !self.is_crate_vis() &&
4413 !self.is_existential_type_decl() &&
4414 !self.is_auto_trait_item() &&
4415 !self.is_async_fn() {
4416 let pth = self.parse_path(PathStyle::Expr)?;
4418 if !self.eat(&token::Not) {
4419 let expr = if self.check(&token::OpenDelim(token::Brace)) {
4420 self.parse_struct_expr(lo, pth, ThinVec::new())?
4422 let hi = self.prev_span;
4423 self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), ThinVec::new())
4426 let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
4427 let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
4428 this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
4431 return Ok(Some(Stmt {
4432 id: ast::DUMMY_NODE_ID,
4433 node: StmtKind::Expr(expr),
4434 span: lo.to(self.prev_span),
4438 // it's a macro invocation
4439 let id = match self.token {
4440 token::OpenDelim(_) => Ident::invalid(), // no special identifier
4441 _ => self.parse_ident()?,
4444 // check that we're pointing at delimiters (need to check
4445 // again after the `if`, because of `parse_ident`
4446 // consuming more tokens).
4448 token::OpenDelim(_) => {}
4450 // we only expect an ident if we didn't parse one
4452 let ident_str = if id.name == kw::Invalid {
4457 let tok_str = self.this_token_descr();
4458 let mut err = self.fatal(&format!("expected {}`(` or `{{`, found {}",
4461 err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str));
4466 let (delim, tts) = self.expect_delimited_token_tree()?;
4467 let hi = self.prev_span;
4469 let style = if delim == MacDelimiter::Brace {
4470 MacStmtStyle::Braces
4472 MacStmtStyle::NoBraces
4475 if id.name == kw::Invalid {
4476 let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim });
4477 let node = if delim == MacDelimiter::Brace ||
4478 self.token == token::Semi || self.token == token::Eof {
4479 StmtKind::Mac(P((mac, style, attrs.into())))
4481 // We used to incorrectly stop parsing macro-expanded statements here.
4482 // If the next token will be an error anyway but could have parsed with the
4483 // earlier behavior, stop parsing here and emit a warning to avoid breakage.
4484 else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token {
4485 // These can continue an expression, so we can't stop parsing and warn.
4486 token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
4487 token::BinOp(token::Minus) | token::BinOp(token::Star) |
4488 token::BinOp(token::And) | token::BinOp(token::Or) |
4489 token::AndAnd | token::OrOr |
4490 token::DotDot | token::DotDotDot | token::DotDotEq => false,
4493 self.warn_missing_semicolon();
4494 StmtKind::Mac(P((mac, style, attrs.into())))
4496 let e = self.mk_expr(mac.span, ExprKind::Mac(mac), ThinVec::new());
4497 let e = self.maybe_recover_from_bad_qpath(e, true)?;
4498 let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
4499 let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
4503 id: ast::DUMMY_NODE_ID,
4508 // if it has a special ident, it's definitely an item
4510 // Require a semicolon or braces.
4511 if style != MacStmtStyle::Braces && !self.eat(&token::Semi) {
4512 self.report_invalid_macro_expansion_item();
4514 let span = lo.to(hi);
4516 id: ast::DUMMY_NODE_ID,
4518 node: StmtKind::Item({
4520 span, id /*id is good here*/,
4521 ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })),
4522 respan(lo, VisibilityKind::Inherited),
4528 // FIXME: Bad copy of attrs
4529 let old_directory_ownership =
4530 mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
4531 let item = self.parse_item_(attrs.clone(), false, true)?;
4532 self.directory.ownership = old_directory_ownership;
4536 id: ast::DUMMY_NODE_ID,
4537 span: lo.to(i.span),
4538 node: StmtKind::Item(i),
4541 let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
4542 if !attrs.is_empty() {
4543 if s.prev_token_kind == PrevTokenKind::DocComment {
4544 s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
4545 } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
4546 s.span_err(s.span, "expected statement after outer attribute");
4551 // Do not attempt to parse an expression if we're done here.
4552 if self.token == token::Semi {
4553 unused_attrs(&attrs, self);
4558 if self.token == token::CloseDelim(token::Brace) {
4559 unused_attrs(&attrs, self);
4563 // Remainder are line-expr stmts.
4564 let e = self.parse_expr_res(
4565 Restrictions::STMT_EXPR, Some(attrs.into()))?;
4567 id: ast::DUMMY_NODE_ID,
4568 span: lo.to(e.span),
4569 node: StmtKind::Expr(e),
4576 /// Checks if this expression is a successfully parsed statement.
4577 fn expr_is_complete(&self, e: &Expr) -> bool {
4578 self.restrictions.contains(Restrictions::STMT_EXPR) &&
4579 !classify::expr_requires_semi_to_be_stmt(e)
4582 /// Parses a block. No inner attributes are allowed.
4583 pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
4584 maybe_whole!(self, NtBlock, |x| x);
4588 if !self.eat(&token::OpenDelim(token::Brace)) {
4590 let tok = self.this_token_descr();
4591 let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok));
4592 let do_not_suggest_help =
4593 self.token.is_keyword(kw::In) || self.token == token::Colon;
4595 if self.token.is_ident_named(sym::and) {
4596 e.span_suggestion_short(
4598 "use `&&` instead of `and` for the boolean operator",
4600 Applicability::MaybeIncorrect,
4603 if self.token.is_ident_named(sym::or) {
4604 e.span_suggestion_short(
4606 "use `||` instead of `or` for the boolean operator",
4608 Applicability::MaybeIncorrect,
4612 // Check to see if the user has written something like
4617 // Which is valid in other languages, but not Rust.
4618 match self.parse_stmt_without_recovery(false) {
4620 if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
4621 || do_not_suggest_help {
4622 // if the next token is an open brace (e.g., `if a b {`), the place-
4623 // inside-a-block suggestion would be more likely wrong than right
4624 e.span_label(sp, "expected `{`");
4627 let mut stmt_span = stmt.span;
4628 // expand the span to include the semicolon, if it exists
4629 if self.eat(&token::Semi) {
4630 stmt_span = stmt_span.with_hi(self.prev_span.hi());
4632 let sugg = pprust::to_string(|s| {
4633 use crate::print::pprust::{PrintState, INDENT_UNIT};
4634 s.ibox(INDENT_UNIT)?;
4636 s.print_stmt(&stmt)?;
4637 s.bclose_maybe_open(stmt.span, INDENT_UNIT, false)
4641 "try placing this code inside a block",
4643 // speculative, has been misleading in the past (closed Issue #46836)
4644 Applicability::MaybeIncorrect
4648 self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
4649 self.cancel(&mut e);
4653 e.span_label(sp, "expected `{`");
4657 self.parse_block_tail(lo, BlockCheckMode::Default)
4660 /// Parses a block. Inner attributes are allowed.
4661 fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
4662 maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
4665 self.expect(&token::OpenDelim(token::Brace))?;
4666 Ok((self.parse_inner_attributes()?,
4667 self.parse_block_tail(lo, BlockCheckMode::Default)?))
4670 /// Parses the rest of a block expression or function body.
4671 /// Precondition: already parsed the '{'.
4672 fn parse_block_tail(&mut self, lo: Span, s: BlockCheckMode) -> PResult<'a, P<Block>> {
4673 let mut stmts = vec![];
4674 while !self.eat(&token::CloseDelim(token::Brace)) {
4675 let stmt = match self.parse_full_stmt(false) {
4678 self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
4680 id: ast::DUMMY_NODE_ID,
4681 node: StmtKind::Expr(DummyResult::raw_expr(self.span, true)),
4687 if let Some(stmt) = stmt {
4689 } else if self.token == token::Eof {
4692 // Found only `;` or `}`.
4698 id: ast::DUMMY_NODE_ID,
4700 span: lo.to(self.prev_span),
4704 /// Parses a statement, including the trailing semicolon.
4705 crate fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
4706 // skip looking for a trailing semicolon when we have an interpolated statement
4707 maybe_whole!(self, NtStmt, |x| Some(x));
4709 let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
4711 None => return Ok(None),
4715 StmtKind::Expr(ref expr) if self.token != token::Eof => {
4716 // expression without semicolon
4717 if classify::expr_requires_semi_to_be_stmt(expr) {
4718 // Just check for errors and recover; do not eat semicolon yet.
4720 self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
4723 self.recover_stmt();
4727 StmtKind::Local(..) => {
4728 // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
4729 if macro_legacy_warnings && self.token != token::Semi {
4730 self.warn_missing_semicolon();
4732 self.expect_one_of(&[], &[token::Semi])?;
4738 if self.eat(&token::Semi) {
4739 stmt = stmt.add_trailing_semicolon();
4742 stmt.span = stmt.span.with_hi(self.prev_span.hi());
4746 fn warn_missing_semicolon(&self) {
4747 self.diagnostic().struct_span_warn(self.span, {
4748 &format!("expected `;`, found {}", self.this_token_descr())
4750 "This was erroneously allowed and will become a hard error in a future release"
4754 fn err_dotdotdot_syntax(&self, span: Span) {
4755 self.diagnostic().struct_span_err(span, {
4756 "unexpected token: `...`"
4758 span, "use `..` for an exclusive range", "..".to_owned(),
4759 Applicability::MaybeIncorrect
4761 span, "or `..=` for an inclusive range", "..=".to_owned(),
4762 Applicability::MaybeIncorrect
4766 /// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`.
4769 /// BOUND = TY_BOUND | LT_BOUND
4770 /// LT_BOUND = LIFETIME (e.g., `'a`)
4771 /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
4772 /// TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
4774 fn parse_generic_bounds_common(&mut self,
4776 colon_span: Option<Span>) -> PResult<'a, GenericBounds> {
4777 let mut bounds = Vec::new();
4778 let mut negative_bounds = Vec::new();
4779 let mut last_plus_span = None;
4780 let mut was_negative = false;
4782 // This needs to be synchronized with `Token::can_begin_bound`.
4783 let is_bound_start = self.check_path() || self.check_lifetime() ||
4784 self.check(&token::Not) || // used for error reporting only
4785 self.check(&token::Question) ||
4786 self.check_keyword(kw::For) ||
4787 self.check(&token::OpenDelim(token::Paren));
4790 let has_parens = self.eat(&token::OpenDelim(token::Paren));
4791 let inner_lo = self.span;
4792 let is_negative = self.eat(&token::Not);
4793 let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
4794 if self.token.is_lifetime() {
4795 if let Some(question_span) = question {
4796 self.span_err(question_span,
4797 "`?` may only modify trait bounds, not lifetime bounds");
4799 bounds.push(GenericBound::Outlives(self.expect_lifetime()));
4801 let inner_span = inner_lo.to(self.prev_span);
4802 self.expect(&token::CloseDelim(token::Paren))?;
4803 let mut err = self.struct_span_err(
4804 lo.to(self.prev_span),
4805 "parenthesized lifetime bounds are not supported"
4807 if let Ok(snippet) = self.sess.source_map().span_to_snippet(inner_span) {
4808 err.span_suggestion_short(
4809 lo.to(self.prev_span),
4810 "remove the parentheses",
4812 Applicability::MachineApplicable
4818 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
4819 let path = self.parse_path(PathStyle::Type)?;
4821 self.expect(&token::CloseDelim(token::Paren))?;
4823 let poly_span = lo.to(self.prev_span);
4825 was_negative = true;
4826 if let Some(sp) = last_plus_span.or(colon_span) {
4827 negative_bounds.push(sp.to(poly_span));
4830 let poly_trait = PolyTraitRef::new(lifetime_defs, path, poly_span);
4831 let modifier = if question.is_some() {
4832 TraitBoundModifier::Maybe
4834 TraitBoundModifier::None
4836 bounds.push(GenericBound::Trait(poly_trait, modifier));
4843 if !allow_plus || !self.eat_plus() {
4846 last_plus_span = Some(self.prev_span);
4850 if !negative_bounds.is_empty() || was_negative {
4851 let plural = negative_bounds.len() > 1;
4852 let last_span = negative_bounds.last().map(|sp| *sp);
4853 let mut err = self.struct_span_err(
4855 "negative trait bounds are not supported",
4857 if let Some(sp) = last_span {
4858 err.span_label(sp, "negative trait bounds are not supported");
4860 if let Some(bound_list) = colon_span {
4861 let bound_list = bound_list.to(self.prev_span);
4862 let mut new_bound_list = String::new();
4863 if !bounds.is_empty() {
4864 let mut snippets = bounds.iter().map(|bound| bound.span())
4865 .map(|span| self.sess.source_map().span_to_snippet(span));
4866 while let Some(Ok(snippet)) = snippets.next() {
4867 new_bound_list.push_str(" + ");
4868 new_bound_list.push_str(&snippet);
4870 new_bound_list = new_bound_list.replacen(" +", ":", 1);
4872 err.span_suggestion_hidden(
4874 &format!("remove the trait bound{}", if plural { "s" } else { "" }),
4876 Applicability::MachineApplicable,
4885 crate fn parse_generic_bounds(&mut self,
4886 colon_span: Option<Span>) -> PResult<'a, GenericBounds> {
4887 self.parse_generic_bounds_common(true, colon_span)
4890 /// Parses bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
4893 /// BOUND = LT_BOUND (e.g., `'a`)
4895 fn parse_lt_param_bounds(&mut self) -> GenericBounds {
4896 let mut lifetimes = Vec::new();
4897 while self.check_lifetime() {
4898 lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
4900 if !self.eat_plus() {
4907 /// Matches `typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?`.
4908 fn parse_ty_param(&mut self,
4909 preceding_attrs: Vec<Attribute>)
4910 -> PResult<'a, GenericParam> {
4911 let ident = self.parse_ident()?;
4913 // Parse optional colon and param bounds.
4914 let bounds = if self.eat(&token::Colon) {
4915 self.parse_generic_bounds(Some(self.prev_span))?
4920 let default = if self.eat(&token::Eq) {
4921 Some(self.parse_ty()?)
4928 id: ast::DUMMY_NODE_ID,
4929 attrs: preceding_attrs.into(),
4931 kind: GenericParamKind::Type {
4937 /// Parses the following grammar:
4939 /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
4940 fn parse_trait_item_assoc_ty(&mut self)
4941 -> PResult<'a, (Ident, TraitItemKind, ast::Generics)> {
4942 let ident = self.parse_ident()?;
4943 let mut generics = self.parse_generics()?;
4945 // Parse optional colon and param bounds.
4946 let bounds = if self.eat(&token::Colon) {
4947 self.parse_generic_bounds(None)?
4951 generics.where_clause = self.parse_where_clause()?;
4953 let default = if self.eat(&token::Eq) {
4954 Some(self.parse_ty()?)
4958 self.expect(&token::Semi)?;
4960 Ok((ident, TraitItemKind::Type(bounds, default), generics))
4963 fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> {
4964 self.expect_keyword(kw::Const)?;
4965 let ident = self.parse_ident()?;
4966 self.expect(&token::Colon)?;
4967 let ty = self.parse_ty()?;
4971 id: ast::DUMMY_NODE_ID,
4972 attrs: preceding_attrs.into(),
4974 kind: GenericParamKind::Const {
4980 /// Parses a (possibly empty) list of lifetime and type parameters, possibly including
4981 /// a trailing comma and erroneous trailing attributes.
4982 crate fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
4983 let mut params = Vec::new();
4985 let attrs = self.parse_outer_attributes()?;
4986 if self.check_lifetime() {
4987 let lifetime = self.expect_lifetime();
4988 // Parse lifetime parameter.
4989 let bounds = if self.eat(&token::Colon) {
4990 self.parse_lt_param_bounds()
4994 params.push(ast::GenericParam {
4995 ident: lifetime.ident,
4997 attrs: attrs.into(),
4999 kind: ast::GenericParamKind::Lifetime,
5001 } else if self.check_keyword(kw::Const) {
5002 // Parse const parameter.
5003 params.push(self.parse_const_param(attrs)?);
5004 } else if self.check_ident() {
5005 // Parse type parameter.
5006 params.push(self.parse_ty_param(attrs)?);
5008 // Check for trailing attributes and stop parsing.
5009 if !attrs.is_empty() {
5010 if !params.is_empty() {
5011 self.struct_span_err(
5013 &format!("trailing attribute after generic parameter"),
5015 .span_label(attrs[0].span, "attributes must go before parameters")
5018 self.struct_span_err(
5020 &format!("attribute without generic parameters"),
5024 "attributes are only permitted when preceding parameters",
5032 if !self.eat(&token::Comma) {
5039 /// Parses a set of optional generic type parameter declarations. Where
5040 /// clauses are not parsed here, and must be added later via
5041 /// `parse_where_clause()`.
5043 /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
5044 /// | ( < lifetimes , typaramseq ( , )? > )
5045 /// where typaramseq = ( typaram ) | ( typaram , typaramseq )
5046 fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
5047 let span_lo = self.span;
5049 let params = self.parse_generic_params()?;
5053 where_clause: WhereClause {
5054 id: ast::DUMMY_NODE_ID,
5055 predicates: Vec::new(),
5058 span: span_lo.to(self.prev_span),
5061 Ok(ast::Generics::default())
5065 /// Parses generic args (within a path segment) with recovery for extra leading angle brackets.
5066 /// For the purposes of understanding the parsing logic of generic arguments, this function
5067 /// can be thought of being the same as just calling `self.parse_generic_args()` if the source
5068 /// had the correct amount of leading angle brackets.
5070 /// ```ignore (diagnostics)
5071 /// bar::<<<<T as Foo>::Output>();
5072 /// ^^ help: remove extra angle brackets
5074 fn parse_generic_args_with_leaning_angle_bracket_recovery(
5078 ) -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
5079 // We need to detect whether there are extra leading left angle brackets and produce an
5080 // appropriate error and suggestion. This cannot be implemented by looking ahead at
5081 // upcoming tokens for a matching `>` character - if there are unmatched `<` tokens
5082 // then there won't be matching `>` tokens to find.
5084 // To explain how this detection works, consider the following example:
5086 // ```ignore (diagnostics)
5087 // bar::<<<<T as Foo>::Output>();
5088 // ^^ help: remove extra angle brackets
5091 // Parsing of the left angle brackets starts in this function. We start by parsing the
5092 // `<` token (incrementing the counter of unmatched angle brackets on `Parser` via
5095 // *Upcoming tokens:* `<<<<T as Foo>::Output>;`
5096 // *Unmatched count:* 1
5097 // *`parse_path_segment` calls deep:* 0
5099 // This has the effect of recursing as this function is called if a `<` character
5100 // is found within the expected generic arguments:
5102 // *Upcoming tokens:* `<<<T as Foo>::Output>;`
5103 // *Unmatched count:* 2
5104 // *`parse_path_segment` calls deep:* 1
5106 // Eventually we will have recursed until having consumed all of the `<` tokens and
5107 // this will be reflected in the count:
5109 // *Upcoming tokens:* `T as Foo>::Output>;`
5110 // *Unmatched count:* 4
5111 // `parse_path_segment` calls deep:* 3
5113 // The parser will continue until reaching the first `>` - this will decrement the
5114 // unmatched angle bracket count and return to the parent invocation of this function
5115 // having succeeded in parsing:
5117 // *Upcoming tokens:* `::Output>;`
5118 // *Unmatched count:* 3
5119 // *`parse_path_segment` calls deep:* 2
5121 // This will continue until the next `>` character which will also return successfully
5122 // to the parent invocation of this function and decrement the count:
5124 // *Upcoming tokens:* `;`
5125 // *Unmatched count:* 2
5126 // *`parse_path_segment` calls deep:* 1
5128 // At this point, this function will expect to find another matching `>` character but
5129 // won't be able to and will return an error. This will continue all the way up the
5130 // call stack until the first invocation:
5132 // *Upcoming tokens:* `;`
5133 // *Unmatched count:* 2
5134 // *`parse_path_segment` calls deep:* 0
5136 // In doing this, we have managed to work out how many unmatched leading left angle
5137 // brackets there are, but we cannot recover as the unmatched angle brackets have
5138 // already been consumed. To remedy this, we keep a snapshot of the parser state
5139 // before we do the above. We can then inspect whether we ended up with a parsing error
5140 // and unmatched left angle brackets and if so, restore the parser state before we
5141 // consumed any `<` characters to emit an error and consume the erroneous tokens to
5142 // recover by attempting to parse again.
5144 // In practice, the recursion of this function is indirect and there will be other
5145 // locations that consume some `<` characters - as long as we update the count when
5146 // this happens, it isn't an issue.
5148 let is_first_invocation = style == PathStyle::Expr;
5149 // Take a snapshot before attempting to parse - we can restore this later.
5150 let snapshot = if is_first_invocation {
5156 debug!("parse_generic_args_with_leading_angle_bracket_recovery: (snapshotting)");
5157 match self.parse_generic_args() {
5158 Ok(value) => Ok(value),
5159 Err(ref mut e) if is_first_invocation && self.unmatched_angle_bracket_count > 0 => {
5160 // Cancel error from being unable to find `>`. We know the error
5161 // must have been this due to a non-zero unmatched angle bracket
5165 // Swap `self` with our backup of the parser state before attempting to parse
5166 // generic arguments.
5167 let snapshot = mem::replace(self, snapshot.unwrap());
5170 "parse_generic_args_with_leading_angle_bracket_recovery: (snapshot failure) \
5171 snapshot.count={:?}",
5172 snapshot.unmatched_angle_bracket_count,
5175 // Eat the unmatched angle brackets.
5176 for _ in 0..snapshot.unmatched_angle_bracket_count {
5180 // Make a span over ${unmatched angle bracket count} characters.
5181 let span = lo.with_hi(
5182 lo.lo() + BytePos(snapshot.unmatched_angle_bracket_count)
5184 let plural = snapshot.unmatched_angle_bracket_count > 1;
5189 "unmatched angle bracket{}",
5190 if plural { "s" } else { "" }
5196 "remove extra angle bracket{}",
5197 if plural { "s" } else { "" }
5200 Applicability::MachineApplicable,
5204 // Try again without unmatched angle bracket characters.
5205 self.parse_generic_args()
5211 /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
5212 /// possibly including trailing comma.
5213 fn parse_generic_args(&mut self) -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
5214 let mut args = Vec::new();
5215 let mut bindings = Vec::new();
5216 let mut misplaced_assoc_ty_bindings: Vec<Span> = Vec::new();
5217 let mut assoc_ty_bindings: Vec<Span> = Vec::new();
5219 let args_lo = self.span;
5222 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5223 // Parse lifetime argument.
5224 args.push(GenericArg::Lifetime(self.expect_lifetime()));
5225 misplaced_assoc_ty_bindings.append(&mut assoc_ty_bindings);
5226 } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
5227 // Parse associated type binding.
5229 let ident = self.parse_ident()?;
5231 let ty = self.parse_ty()?;
5232 let span = lo.to(self.prev_span);
5233 bindings.push(TypeBinding {
5234 id: ast::DUMMY_NODE_ID,
5239 assoc_ty_bindings.push(span);
5240 } else if self.check_const_arg() {
5241 // Parse const argument.
5242 let expr = if let token::OpenDelim(token::Brace) = self.token {
5243 self.parse_block_expr(None, self.span, BlockCheckMode::Default, ThinVec::new())?
5244 } else if self.token.is_ident() {
5245 // FIXME(const_generics): to distinguish between idents for types and consts,
5246 // we should introduce a GenericArg::Ident in the AST and distinguish when
5247 // lowering to the HIR. For now, idents for const args are not permitted.
5249 self.fatal("identifiers may currently not be used for const generics")
5252 self.parse_literal_maybe_minus()?
5254 let value = AnonConst {
5255 id: ast::DUMMY_NODE_ID,
5258 args.push(GenericArg::Const(value));
5259 misplaced_assoc_ty_bindings.append(&mut assoc_ty_bindings);
5260 } else if self.check_type() {
5261 // Parse type argument.
5262 args.push(GenericArg::Type(self.parse_ty()?));
5263 misplaced_assoc_ty_bindings.append(&mut assoc_ty_bindings);
5268 if !self.eat(&token::Comma) {
5273 // FIXME: we would like to report this in ast_validation instead, but we currently do not
5274 // preserve ordering of generic parameters with respect to associated type binding, so we
5275 // lose that information after parsing.
5276 if misplaced_assoc_ty_bindings.len() > 0 {
5277 let mut err = self.struct_span_err(
5278 args_lo.to(self.prev_span),
5279 "associated type bindings must be declared after generic parameters",
5281 for span in misplaced_assoc_ty_bindings {
5284 "this associated type binding should be moved after the generic parameters",
5290 Ok((args, bindings))
5293 /// Parses an optional where-clause and places it in `generics`.
5295 /// ```ignore (only-for-syntax-highlight)
5296 /// where T : Trait<U, V> + 'b, 'a : 'b
5298 fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
5299 let mut where_clause = WhereClause {
5300 id: ast::DUMMY_NODE_ID,
5301 predicates: Vec::new(),
5305 if !self.eat_keyword(kw::Where) {
5306 return Ok(where_clause);
5308 let lo = self.prev_span;
5310 // We are considering adding generics to the `where` keyword as an alternative higher-rank
5311 // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
5312 // change we parse those generics now, but report an error.
5313 if self.choose_generics_over_qpath() {
5314 let generics = self.parse_generics()?;
5315 self.struct_span_err(
5317 "generic parameters on `where` clauses are reserved for future use",
5319 .span_label(generics.span, "currently unsupported")
5325 if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
5326 let lifetime = self.expect_lifetime();
5327 // Bounds starting with a colon are mandatory, but possibly empty.
5328 self.expect(&token::Colon)?;
5329 let bounds = self.parse_lt_param_bounds();
5330 where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
5331 ast::WhereRegionPredicate {
5332 span: lo.to(self.prev_span),
5337 } else if self.check_type() {
5338 // Parse optional `for<'a, 'b>`.
5339 // This `for` is parsed greedily and applies to the whole predicate,
5340 // the bounded type can have its own `for` applying only to it.
5341 // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/>
5342 // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/>
5343 // Example 3: for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /*ok*/, 'b /*not ok*/>
5344 let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
5346 // Parse type with mandatory colon and (possibly empty) bounds,
5347 // or with mandatory equality sign and the second type.
5348 let ty = self.parse_ty()?;
5349 if self.eat(&token::Colon) {
5350 let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
5351 where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
5352 ast::WhereBoundPredicate {
5353 span: lo.to(self.prev_span),
5354 bound_generic_params: lifetime_defs,
5359 // FIXME: Decide what should be used here, `=` or `==`.
5360 // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
5361 } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
5362 let rhs_ty = self.parse_ty()?;
5363 where_clause.predicates.push(ast::WherePredicate::EqPredicate(
5364 ast::WhereEqPredicate {
5365 span: lo.to(self.prev_span),
5368 id: ast::DUMMY_NODE_ID,
5372 return self.unexpected();
5378 if !self.eat(&token::Comma) {
5383 where_clause.span = lo.to(self.prev_span);
5387 fn parse_fn_args(&mut self, named_args: bool, allow_c_variadic: bool)
5388 -> PResult<'a, (Vec<Arg> , bool)> {
5389 self.expect(&token::OpenDelim(token::Paren))?;
5392 let mut c_variadic = false;
5393 let (args, recovered): (Vec<Option<Arg>>, bool) =
5394 self.parse_seq_to_before_end(
5395 &token::CloseDelim(token::Paren),
5396 SeqSep::trailing_allowed(token::Comma),
5398 // If the argument is a C-variadic argument we should not
5399 // enforce named arguments.
5400 let enforce_named_args = if p.token == token::DotDotDot {
5405 match p.parse_arg_general(enforce_named_args, false,
5408 if let TyKind::CVarArgs = arg.ty.node {
5410 if p.token != token::CloseDelim(token::Paren) {
5413 "`...` must be the last argument of a C-variadic function");
5424 let lo = p.prev_span;
5425 // Skip every token until next possible arg or end.
5426 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
5427 // Create a placeholder argument for proper arg count (issue #34264).
5428 let span = lo.to(p.prev_span);
5429 Ok(Some(dummy_arg(span)))
5436 self.eat(&token::CloseDelim(token::Paren));
5439 let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
5441 if c_variadic && args.is_empty() {
5443 "C-variadic function must be declared with at least one named argument");
5446 Ok((args, c_variadic))
5449 /// Parses the argument list and result type of a function declaration.
5450 fn parse_fn_decl(&mut self, allow_c_variadic: bool) -> PResult<'a, P<FnDecl>> {
5452 let (args, c_variadic) = self.parse_fn_args(true, allow_c_variadic)?;
5453 let ret_ty = self.parse_ret_ty(true)?;
5462 /// Returns the parsed optional self argument and whether a self shortcut was used.
5463 fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
5464 let expect_ident = |this: &mut Self| match this.token {
5465 // Preserve hygienic context.
5466 token::Ident(ident, _) =>
5467 { let span = this.span; this.bump(); Ident::new(ident.name, span) }
5470 let isolated_self = |this: &mut Self, n| {
5471 this.look_ahead(n, |t| t.is_keyword(kw::SelfLower)) &&
5472 this.look_ahead(n + 1, |t| t != &token::ModSep)
5475 // Parse optional self parameter of a method.
5476 // Only a limited set of initial token sequences is considered self parameters, anything
5477 // else is parsed as a normal function parameter list, so some lookahead is required.
5478 let eself_lo = self.span;
5479 let (eself, eself_ident, eself_hi) = match self.token {
5480 token::BinOp(token::And) => {
5486 (if isolated_self(self, 1) {
5488 SelfKind::Region(None, Mutability::Immutable)
5489 } else if self.look_ahead(1, |t| t.is_keyword(kw::Mut)) &&
5490 isolated_self(self, 2) {
5493 SelfKind::Region(None, Mutability::Mutable)
5494 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5495 isolated_self(self, 2) {
5497 let lt = self.expect_lifetime();
5498 SelfKind::Region(Some(lt), Mutability::Immutable)
5499 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
5500 self.look_ahead(2, |t| t.is_keyword(kw::Mut)) &&
5501 isolated_self(self, 3) {
5503 let lt = self.expect_lifetime();
5505 SelfKind::Region(Some(lt), Mutability::Mutable)
5508 }, expect_ident(self), self.prev_span)
5510 token::BinOp(token::Star) => {
5515 // Emit special error for `self` cases.
5516 let msg = "cannot pass `self` by raw pointer";
5517 (if isolated_self(self, 1) {
5519 self.struct_span_err(self.span, msg)
5520 .span_label(self.span, msg)
5522 SelfKind::Value(Mutability::Immutable)
5523 } else if self.look_ahead(1, |t| t.is_mutability()) &&
5524 isolated_self(self, 2) {
5527 self.struct_span_err(self.span, msg)
5528 .span_label(self.span, msg)
5530 SelfKind::Value(Mutability::Immutable)
5533 }, expect_ident(self), self.prev_span)
5535 token::Ident(..) => {
5536 if isolated_self(self, 0) {
5539 let eself_ident = expect_ident(self);
5540 let eself_hi = self.prev_span;
5541 (if self.eat(&token::Colon) {
5542 let ty = self.parse_ty()?;
5543 SelfKind::Explicit(ty, Mutability::Immutable)
5545 SelfKind::Value(Mutability::Immutable)
5546 }, eself_ident, eself_hi)
5547 } else if self.token.is_keyword(kw::Mut) &&
5548 isolated_self(self, 1) {
5552 let eself_ident = expect_ident(self);
5553 let eself_hi = self.prev_span;
5554 (if self.eat(&token::Colon) {
5555 let ty = self.parse_ty()?;
5556 SelfKind::Explicit(ty, Mutability::Mutable)
5558 SelfKind::Value(Mutability::Mutable)
5559 }, eself_ident, eself_hi)
5564 _ => return Ok(None),
5567 let eself = source_map::respan(eself_lo.to(eself_hi), eself);
5568 Ok(Some(Arg::from_self(eself, eself_ident)))
5571 /// Parses the parameter list and result type of a function that may have a `self` parameter.
5572 fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>>
5573 where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
5575 self.expect(&token::OpenDelim(token::Paren))?;
5577 // Parse optional self argument
5578 let self_arg = self.parse_self_arg()?;
5580 // Parse the rest of the function parameter list.
5581 let sep = SeqSep::trailing_allowed(token::Comma);
5582 let (fn_inputs, recovered) = if let Some(self_arg) = self_arg {
5583 if self.check(&token::CloseDelim(token::Paren)) {
5584 (vec![self_arg], false)
5585 } else if self.eat(&token::Comma) {
5586 let mut fn_inputs = vec![self_arg];
5587 let (mut input, recovered) = self.parse_seq_to_before_end(
5588 &token::CloseDelim(token::Paren), sep, parse_arg_fn)?;
5589 fn_inputs.append(&mut input);
5590 (fn_inputs, recovered)
5592 match self.expect_one_of(&[], &[]) {
5593 Err(err) => return Err(err),
5594 Ok(recovered) => (vec![self_arg], recovered),
5598 self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?
5602 // Parse closing paren and return type.
5603 self.expect(&token::CloseDelim(token::Paren))?;
5607 output: self.parse_ret_ty(true)?,
5612 /// Parses the `|arg, arg|` header of a closure.
5613 fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
5614 let inputs_captures = {
5615 if self.eat(&token::OrOr) {
5618 self.expect(&token::BinOp(token::Or))?;
5619 let args = self.parse_seq_to_before_tokens(
5620 &[&token::BinOp(token::Or), &token::OrOr],
5621 SeqSep::trailing_allowed(token::Comma),
5622 TokenExpectType::NoExpect,
5623 |p| p.parse_fn_block_arg()
5629 let output = self.parse_ret_ty(true)?;
5632 inputs: inputs_captures,
5638 /// Parses the name and optional generic types of a function header.
5639 fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
5640 let id = self.parse_ident()?;
5641 let generics = self.parse_generics()?;
5645 fn mk_item(&self, span: Span, ident: Ident, node: ItemKind, vis: Visibility,
5646 attrs: Vec<Attribute>) -> P<Item> {
5650 id: ast::DUMMY_NODE_ID,
5658 /// Parses an item-position function declaration.
5659 fn parse_item_fn(&mut self,
5661 mut asyncness: Spanned<IsAsync>,
5662 constness: Spanned<Constness>,
5664 -> PResult<'a, ItemInfo> {
5665 let (ident, mut generics) = self.parse_fn_header()?;
5666 let allow_c_variadic = abi == Abi::C && unsafety == Unsafety::Unsafe;
5667 let mut decl = self.parse_fn_decl(allow_c_variadic)?;
5668 generics.where_clause = self.parse_where_clause()?;
5669 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5670 self.construct_async_arguments(&mut asyncness, &mut decl);
5671 let header = FnHeader { unsafety, asyncness, constness, abi };
5672 Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
5675 /// Returns `true` if we are looking at `const ID`
5676 /// (returns `false` for things like `const fn`, etc.).
5677 fn is_const_item(&self) -> bool {
5678 self.token.is_keyword(kw::Const) &&
5679 !self.look_ahead(1, |t| t.is_keyword(kw::Fn)) &&
5680 !self.look_ahead(1, |t| t.is_keyword(kw::Unsafe))
5683 /// Parses all the "front matter" for a `fn` declaration, up to
5684 /// and including the `fn` keyword:
5688 /// - `const unsafe fn`
5691 fn parse_fn_front_matter(&mut self)
5699 let is_const_fn = self.eat_keyword(kw::Const);
5700 let const_span = self.prev_span;
5701 let unsafety = self.parse_unsafety();
5702 let asyncness = self.parse_asyncness();
5703 let asyncness = respan(self.prev_span, asyncness);
5704 let (constness, unsafety, abi) = if is_const_fn {
5705 (respan(const_span, Constness::Const), unsafety, Abi::Rust)
5707 let abi = if self.eat_keyword(kw::Extern) {
5708 self.parse_opt_abi()?.unwrap_or(Abi::C)
5712 (respan(self.prev_span, Constness::NotConst), unsafety, abi)
5714 if !self.eat_keyword(kw::Fn) {
5715 // It is possible for `expect_one_of` to recover given the contents of
5716 // `self.expected_tokens`, therefore, do not use `self.unexpected()` which doesn't
5717 // account for this.
5718 if !self.expect_one_of(&[], &[])? { unreachable!() }
5720 Ok((constness, unsafety, asyncness, abi))
5723 /// Parses an impl item.
5724 pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
5725 maybe_whole!(self, NtImplItem, |x| x);
5726 let attrs = self.parse_outer_attributes()?;
5727 let mut unclosed_delims = vec![];
5728 let (mut item, tokens) = self.collect_tokens(|this| {
5729 let item = this.parse_impl_item_(at_end, attrs);
5730 unclosed_delims.append(&mut this.unclosed_delims);
5733 self.unclosed_delims.append(&mut unclosed_delims);
5735 // See `parse_item` for why this clause is here.
5736 if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
5737 item.tokens = Some(tokens);
5742 fn parse_impl_item_(&mut self,
5744 mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> {
5746 let vis = self.parse_visibility(false)?;
5747 let defaultness = self.parse_defaultness();
5748 let (name, node, generics) = if let Some(type_) = self.eat_type() {
5749 let (name, alias, generics) = type_?;
5750 let kind = match alias {
5751 AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ),
5752 AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds),
5754 (name, kind, generics)
5755 } else if self.is_const_item() {
5756 // This parses the grammar:
5757 // ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
5758 self.expect_keyword(kw::Const)?;
5759 let name = self.parse_ident()?;
5760 self.expect(&token::Colon)?;
5761 let typ = self.parse_ty()?;
5762 self.expect(&token::Eq)?;
5763 let expr = self.parse_expr()?;
5764 self.expect(&token::Semi)?;
5765 (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default())
5767 let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?;
5768 attrs.extend(inner_attrs);
5769 (name, node, generics)
5773 id: ast::DUMMY_NODE_ID,
5774 span: lo.to(self.prev_span),
5785 fn complain_if_pub_macro(&self, vis: &VisibilityKind, sp: Span) {
5787 VisibilityKind::Inherited => {}
5789 let is_macro_rules: bool = match self.token {
5790 token::Ident(sid, _) => sid.name == sym::macro_rules,
5793 let mut err = if is_macro_rules {
5794 let mut err = self.diagnostic()
5795 .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
5796 err.span_suggestion(
5798 "try exporting the macro",
5799 "#[macro_export]".to_owned(),
5800 Applicability::MaybeIncorrect // speculative
5804 let mut err = self.diagnostic()
5805 .struct_span_err(sp, "can't qualify macro invocation with `pub`");
5806 err.help("try adjusting the macro to put `pub` inside the invocation");
5814 fn missing_assoc_item_kind_err(&self, item_type: &str, prev_span: Span)
5815 -> DiagnosticBuilder<'a>
5817 let expected_kinds = if item_type == "extern" {
5818 "missing `fn`, `type`, or `static`"
5820 "missing `fn`, `type`, or `const`"
5823 // Given this code `path(`, it seems like this is not
5824 // setting the visibility of a macro invocation, but rather
5825 // a mistyped method declaration.
5826 // Create a diagnostic pointing out that `fn` is missing.
5828 // x | pub path(&self) {
5829 // | ^ missing `fn`, `type`, or `const`
5831 // ^^ `sp` below will point to this
5832 let sp = prev_span.between(self.prev_span);
5833 let mut err = self.diagnostic().struct_span_err(
5835 &format!("{} for {}-item declaration",
5836 expected_kinds, item_type));
5837 err.span_label(sp, expected_kinds);
5841 /// Parse a method or a macro invocation in a trait impl.
5842 fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
5843 -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics,
5844 ast::ImplItemKind)> {
5845 // code copied from parse_macro_use_or_failure... abstraction!
5846 if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
5848 Ok((Ident::invalid(), vec![], ast::Generics::default(),
5849 ast::ImplItemKind::Macro(mac)))
5851 let (constness, unsafety, mut asyncness, abi) = self.parse_fn_front_matter()?;
5852 let ident = self.parse_ident()?;
5853 let mut generics = self.parse_generics()?;
5854 let mut decl = self.parse_fn_decl_with_self(|p| {
5855 p.parse_arg_general(true, true, false)
5857 generics.where_clause = self.parse_where_clause()?;
5858 self.construct_async_arguments(&mut asyncness, &mut decl);
5860 let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
5861 let header = ast::FnHeader { abi, unsafety, constness, asyncness };
5862 Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
5863 ast::MethodSig { header, decl },
5869 /// Parses `trait Foo { ... }` or `trait Foo = Bar;`.
5870 fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5871 let ident = self.parse_ident()?;
5872 let mut tps = self.parse_generics()?;
5874 // Parse optional colon and supertrait bounds.
5875 let bounds = if self.eat(&token::Colon) {
5876 self.parse_generic_bounds(Some(self.prev_span))?
5881 if self.eat(&token::Eq) {
5882 // it's a trait alias
5883 let bounds = self.parse_generic_bounds(None)?;
5884 tps.where_clause = self.parse_where_clause()?;
5885 self.expect(&token::Semi)?;
5886 if is_auto == IsAuto::Yes {
5887 let msg = "trait aliases cannot be `auto`";
5888 self.struct_span_err(self.prev_span, msg)
5889 .span_label(self.prev_span, msg)
5892 if unsafety != Unsafety::Normal {
5893 let msg = "trait aliases cannot be `unsafe`";
5894 self.struct_span_err(self.prev_span, msg)
5895 .span_label(self.prev_span, msg)
5898 Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
5900 // it's a normal trait
5901 tps.where_clause = self.parse_where_clause()?;
5902 self.expect(&token::OpenDelim(token::Brace))?;
5903 let mut trait_items = vec![];
5904 while !self.eat(&token::CloseDelim(token::Brace)) {
5905 if let token::DocComment(_) = self.token {
5906 if self.look_ahead(1,
5907 |tok| tok == &token::Token::CloseDelim(token::Brace)) {
5908 let mut err = self.diagnostic().struct_span_err_with_code(
5910 "found a documentation comment that doesn't document anything",
5911 DiagnosticId::Error("E0584".into()),
5913 err.help("doc comments must come before what they document, maybe a \
5914 comment was intended with `//`?",
5921 let mut at_end = false;
5922 match self.parse_trait_item(&mut at_end) {
5923 Ok(item) => trait_items.push(item),
5927 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5932 Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
5936 fn choose_generics_over_qpath(&self) -> bool {
5937 // There's an ambiguity between generic parameters and qualified paths in impls.
5938 // If we see `<` it may start both, so we have to inspect some following tokens.
5939 // The following combinations can only start generics,
5940 // but not qualified paths (with one exception):
5941 // `<` `>` - empty generic parameters
5942 // `<` `#` - generic parameters with attributes
5943 // `<` (LIFETIME|IDENT) `>` - single generic parameter
5944 // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
5945 // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
5946 // `<` (LIFETIME|IDENT) `=` - generic parameter with a default
5947 // `<` const - generic const parameter
5948 // The only truly ambiguous case is
5949 // `<` IDENT `>` `::` IDENT ...
5950 // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
5951 // because this is what almost always expected in practice, qualified paths in impls
5952 // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
5953 self.token == token::Lt &&
5954 (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
5955 self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
5956 self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
5957 t == &token::Colon || t == &token::Eq) ||
5958 self.look_ahead(1, |t| t.is_keyword(kw::Const)))
5961 fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
5962 self.expect(&token::OpenDelim(token::Brace))?;
5963 let attrs = self.parse_inner_attributes()?;
5965 let mut impl_items = Vec::new();
5966 while !self.eat(&token::CloseDelim(token::Brace)) {
5967 let mut at_end = false;
5968 match self.parse_impl_item(&mut at_end) {
5969 Ok(impl_item) => impl_items.push(impl_item),
5973 self.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
5978 Ok((impl_items, attrs))
5981 /// Parses an implementation item, `impl` keyword is already parsed.
5983 /// impl<'a, T> TYPE { /* impl items */ }
5984 /// impl<'a, T> TRAIT for TYPE { /* impl items */ }
5985 /// impl<'a, T> !TRAIT for TYPE { /* impl items */ }
5987 /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
5988 /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
5989 /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
5990 fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
5991 -> PResult<'a, ItemInfo> {
5992 // First, parse generic parameters if necessary.
5993 let mut generics = if self.choose_generics_over_qpath() {
5994 self.parse_generics()?
5996 ast::Generics::default()
5999 // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
6000 let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
6002 ast::ImplPolarity::Negative
6004 ast::ImplPolarity::Positive
6007 // Parse both types and traits as a type, then reinterpret if necessary.
6008 let err_path = |span| ast::Path::from_ident(Ident::new(kw::Invalid, span));
6009 let ty_first = if self.token.is_keyword(kw::For) &&
6010 self.look_ahead(1, |t| t != &token::Lt) {
6011 let span = self.prev_span.between(self.span);
6012 self.struct_span_err(span, "missing trait in a trait impl").emit();
6013 P(Ty { node: TyKind::Path(None, err_path(span)), span, id: ast::DUMMY_NODE_ID })
6018 // If `for` is missing we try to recover.
6019 let has_for = self.eat_keyword(kw::For);
6020 let missing_for_span = self.prev_span.between(self.span);
6022 let ty_second = if self.token == token::DotDot {
6023 // We need to report this error after `cfg` expansion for compatibility reasons
6024 self.bump(); // `..`, do not add it to expected tokens
6025 Some(DummyResult::raw_ty(self.prev_span, true))
6026 } else if has_for || self.token.can_begin_type() {
6027 Some(self.parse_ty()?)
6032 generics.where_clause = self.parse_where_clause()?;
6034 let (impl_items, attrs) = self.parse_impl_body()?;
6036 let item_kind = match ty_second {
6037 Some(ty_second) => {
6038 // impl Trait for Type
6040 self.struct_span_err(missing_for_span, "missing `for` in a trait impl")
6041 .span_suggestion_short(
6044 " for ".to_string(),
6045 Applicability::MachineApplicable,
6049 let ty_first = ty_first.into_inner();
6050 let path = match ty_first.node {
6051 // This notably includes paths passed through `ty` macro fragments (#46438).
6052 TyKind::Path(None, path) => path,
6054 self.span_err(ty_first.span, "expected a trait, found type");
6055 err_path(ty_first.span)
6058 let trait_ref = TraitRef { path, ref_id: ty_first.id };
6060 ItemKind::Impl(unsafety, polarity, defaultness,
6061 generics, Some(trait_ref), ty_second, impl_items)
6065 ItemKind::Impl(unsafety, polarity, defaultness,
6066 generics, None, ty_first, impl_items)
6070 Ok((Ident::invalid(), item_kind, Some(attrs)))
6073 fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
6074 if self.eat_keyword(kw::For) {
6076 let params = self.parse_generic_params()?;
6078 // We rely on AST validation to rule out invalid cases: There must not be type
6079 // parameters, and the lifetime parameters must not have bounds.
6086 /// Parses `struct Foo { ... }`.
6087 fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
6088 let class_name = self.parse_ident()?;
6090 let mut generics = self.parse_generics()?;
6092 // There is a special case worth noting here, as reported in issue #17904.
6093 // If we are parsing a tuple struct it is the case that the where clause
6094 // should follow the field list. Like so:
6096 // struct Foo<T>(T) where T: Copy;
6098 // If we are parsing a normal record-style struct it is the case
6099 // that the where clause comes before the body, and after the generics.
6100 // So if we look ahead and see a brace or a where-clause we begin
6101 // parsing a record style struct.
6103 // Otherwise if we look ahead and see a paren we parse a tuple-style
6106 let vdata = if self.token.is_keyword(kw::Where) {
6107 generics.where_clause = self.parse_where_clause()?;
6108 if self.eat(&token::Semi) {
6109 // If we see a: `struct Foo<T> where T: Copy;` style decl.
6110 VariantData::Unit(ast::DUMMY_NODE_ID)
6112 // If we see: `struct Foo<T> where T: Copy { ... }`
6113 let (fields, recovered) = self.parse_record_struct_body()?;
6114 VariantData::Struct(fields, recovered)
6116 // No `where` so: `struct Foo<T>;`
6117 } else if self.eat(&token::Semi) {
6118 VariantData::Unit(ast::DUMMY_NODE_ID)
6119 // Record-style struct definition
6120 } else if self.token == token::OpenDelim(token::Brace) {
6121 let (fields, recovered) = self.parse_record_struct_body()?;
6122 VariantData::Struct(fields, recovered)
6123 // Tuple-style struct definition with optional where-clause.
6124 } else if self.token == token::OpenDelim(token::Paren) {
6125 let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID);
6126 generics.where_clause = self.parse_where_clause()?;
6127 self.expect(&token::Semi)?;
6130 let token_str = self.this_token_descr();
6131 let mut err = self.fatal(&format!(
6132 "expected `where`, `{{`, `(`, or `;` after struct name, found {}",
6135 err.span_label(self.span, "expected `where`, `{`, `(`, or `;` after struct name");
6139 Ok((class_name, ItemKind::Struct(vdata, generics), None))
6142 /// Parses `union Foo { ... }`.
6143 fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
6144 let class_name = self.parse_ident()?;
6146 let mut generics = self.parse_generics()?;
6148 let vdata = if self.token.is_keyword(kw::Where) {
6149 generics.where_clause = self.parse_where_clause()?;
6150 let (fields, recovered) = self.parse_record_struct_body()?;
6151 VariantData::Struct(fields, recovered)
6152 } else if self.token == token::OpenDelim(token::Brace) {
6153 let (fields, recovered) = self.parse_record_struct_body()?;
6154 VariantData::Struct(fields, recovered)
6156 let token_str = self.this_token_descr();
6157 let mut err = self.fatal(&format!(
6158 "expected `where` or `{{` after union name, found {}", token_str));
6159 err.span_label(self.span, "expected `where` or `{` after union name");
6163 Ok((class_name, ItemKind::Union(vdata, generics), None))
6166 fn parse_record_struct_body(
6168 ) -> PResult<'a, (Vec<StructField>, /* recovered */ bool)> {
6169 let mut fields = Vec::new();
6170 let mut recovered = false;
6171 if self.eat(&token::OpenDelim(token::Brace)) {
6172 while self.token != token::CloseDelim(token::Brace) {
6173 let field = self.parse_struct_decl_field().map_err(|e| {
6174 self.recover_stmt();
6179 Ok(field) => fields.push(field),
6185 self.eat(&token::CloseDelim(token::Brace));
6187 let token_str = self.this_token_descr();
6188 let mut err = self.fatal(&format!(
6189 "expected `where`, or `{{` after struct name, found {}", token_str));
6190 err.span_label(self.span, "expected `where`, or `{` after struct name");
6194 Ok((fields, recovered))
6197 fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
6198 // This is the case where we find `struct Foo<T>(T) where T: Copy;`
6199 // Unit like structs are handled in parse_item_struct function
6200 let fields = self.parse_unspanned_seq(
6201 &token::OpenDelim(token::Paren),
6202 &token::CloseDelim(token::Paren),
6203 SeqSep::trailing_allowed(token::Comma),
6205 let attrs = p.parse_outer_attributes()?;
6207 let vis = p.parse_visibility(true)?;
6208 let ty = p.parse_ty()?;
6210 span: lo.to(ty.span),
6213 id: ast::DUMMY_NODE_ID,
6222 /// Parses a structure field declaration.
6223 fn parse_single_struct_field(&mut self,
6226 attrs: Vec<Attribute> )
6227 -> PResult<'a, StructField> {
6228 let mut seen_comma: bool = false;
6229 let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
6230 if self.token == token::Comma {
6237 token::CloseDelim(token::Brace) => {}
6238 token::DocComment(_) => {
6239 let previous_span = self.prev_span;
6240 let mut err = self.span_fatal_err(self.span, Error::UselessDocComment);
6241 self.bump(); // consume the doc comment
6242 let comma_after_doc_seen = self.eat(&token::Comma);
6243 // `seen_comma` is always false, because we are inside doc block
6244 // condition is here to make code more readable
6245 if seen_comma == false && comma_after_doc_seen == true {
6248 if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
6251 if seen_comma == false {
6252 let sp = self.sess.source_map().next_point(previous_span);
6253 err.span_suggestion(
6255 "missing comma here",
6257 Applicability::MachineApplicable
6264 let sp = self.sess.source_map().next_point(self.prev_span);
6265 let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}",
6266 self.this_token_descr()));
6267 if self.token.is_ident() {
6268 // This is likely another field; emit the diagnostic and keep going
6269 err.span_suggestion(
6271 "try adding a comma",
6273 Applicability::MachineApplicable,
6284 /// Parses an element of a struct declaration.
6285 fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
6286 let attrs = self.parse_outer_attributes()?;
6288 let vis = self.parse_visibility(false)?;
6289 self.parse_single_struct_field(lo, vis, attrs)
6292 /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
6293 /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
6294 /// If the following element can't be a tuple (i.e., it's a function definition), then
6295 /// it's not a tuple struct field), and the contents within the parentheses isn't valid,
6296 /// so emit a proper diagnostic.
6297 pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
6298 maybe_whole!(self, NtVis, |x| x);
6300 self.expected_tokens.push(TokenType::Keyword(kw::Crate));
6301 if self.is_crate_vis() {
6302 self.bump(); // `crate`
6303 return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
6306 if !self.eat_keyword(kw::Pub) {
6307 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
6308 // keyword to grab a span from for inherited visibility; an empty span at the
6309 // beginning of the current token would seem to be the "Schelling span".
6310 return Ok(respan(self.span.shrink_to_lo(), VisibilityKind::Inherited))
6312 let lo = self.prev_span;
6314 if self.check(&token::OpenDelim(token::Paren)) {
6315 // We don't `self.bump()` the `(` yet because this might be a struct definition where
6316 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
6317 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
6318 // by the following tokens.
6319 if self.look_ahead(1, |t| t.is_keyword(kw::Crate)) &&
6320 self.look_ahead(2, |t| t != &token::ModSep) // account for `pub(crate::foo)`
6324 self.bump(); // `crate`
6325 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6327 lo.to(self.prev_span),
6328 VisibilityKind::Crate(CrateSugar::PubCrate),
6331 } else if self.look_ahead(1, |t| t.is_keyword(kw::In)) {
6334 self.bump(); // `in`
6335 let path = self.parse_path(PathStyle::Mod)?; // `path`
6336 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6337 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6339 id: ast::DUMMY_NODE_ID,
6342 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
6343 self.look_ahead(1, |t| t.is_keyword(kw::Super) ||
6344 t.is_keyword(kw::SelfLower))
6346 // `pub(self)` or `pub(super)`
6348 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
6349 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6350 let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted {
6352 id: ast::DUMMY_NODE_ID,
6355 } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct
6356 // `pub(something) fn ...` or `struct X { pub(something) y: Z }`
6358 let msg = "incorrect visibility restriction";
6359 let suggestion = r##"some possible visibility restrictions are:
6360 `pub(crate)`: visible only on the current crate
6361 `pub(super)`: visible only in the current module's parent
6362 `pub(in path::to::module)`: visible only on the specified path"##;
6363 let path = self.parse_path(PathStyle::Mod)?;
6365 let help_msg = format!("make this visible only to module `{}` with `in`", path);
6366 self.expect(&token::CloseDelim(token::Paren))?; // `)`
6367 let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg);
6368 err.help(suggestion);
6369 err.span_suggestion(
6370 sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable
6372 err.emit(); // emit diagnostic, but continue with public visibility
6376 Ok(respan(lo, VisibilityKind::Public))
6379 /// Parses defaultness (i.e., `default` or nothing).
6380 fn parse_defaultness(&mut self) -> Defaultness {
6381 // `pub` is included for better error messages
6382 if self.check_keyword(kw::Default) &&
6383 self.look_ahead(1, |t| t.is_keyword(kw::Impl) ||
6384 t.is_keyword(kw::Const) ||
6385 t.is_keyword(kw::Fn) ||
6386 t.is_keyword(kw::Unsafe) ||
6387 t.is_keyword(kw::Extern) ||
6388 t.is_keyword(kw::Type) ||
6389 t.is_keyword(kw::Pub)) {
6390 self.bump(); // `default`
6391 Defaultness::Default
6397 /// Given a termination token, parses all of the items in a module.
6398 fn parse_mod_items(&mut self, term: &token::Token, inner_lo: Span) -> PResult<'a, Mod> {
6399 let mut items = vec![];
6400 while let Some(item) = self.parse_item()? {
6402 self.maybe_consume_incorrect_semicolon(&items);
6405 if !self.eat(term) {
6406 let token_str = self.this_token_descr();
6407 if !self.maybe_consume_incorrect_semicolon(&items) {
6408 let mut err = self.fatal(&format!("expected item, found {}", token_str));
6409 err.span_label(self.span, "expected item");
6414 let hi = if self.span.is_dummy() {
6421 inner: inner_lo.to(hi),
6427 fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
6428 let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?;
6429 self.expect(&token::Colon)?;
6430 let ty = self.parse_ty()?;
6431 self.expect(&token::Eq)?;
6432 let e = self.parse_expr()?;
6433 self.expect(&token::Semi)?;
6434 let item = match m {
6435 Some(m) => ItemKind::Static(ty, m, e),
6436 None => ItemKind::Const(ty, e),
6438 Ok((id, item, None))
6441 /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
6442 fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
6443 let (in_cfg, outer_attrs) = {
6444 let mut strip_unconfigured = crate::config::StripUnconfigured {
6446 features: None, // don't perform gated feature checking
6448 let mut outer_attrs = outer_attrs.to_owned();
6449 strip_unconfigured.process_cfg_attrs(&mut outer_attrs);
6450 (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), outer_attrs)
6453 let id_span = self.span;
6454 let id = self.parse_ident()?;
6455 if self.eat(&token::Semi) {
6456 if in_cfg && self.recurse_into_file_modules {
6457 // This mod is in an external file. Let's go get it!
6458 let ModulePathSuccess { path, directory_ownership, warn } =
6459 self.submod_path(id, &outer_attrs, id_span)?;
6460 let (module, mut attrs) =
6461 self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
6462 // Record that we fetched the mod from an external file
6464 let attr = Attribute {
6465 id: attr::mk_attr_id(),
6466 style: ast::AttrStyle::Outer,
6467 path: ast::Path::from_ident(
6468 Ident::with_empty_ctxt(sym::warn_directory_ownership)),
6469 tokens: TokenStream::empty(),
6470 is_sugared_doc: false,
6473 attr::mark_known(&attr);
6476 Ok((id, ItemKind::Mod(module), Some(attrs)))
6478 let placeholder = ast::Mod {
6483 Ok((id, ItemKind::Mod(placeholder), None))
6486 let old_directory = self.directory.clone();
6487 self.push_directory(id, &outer_attrs);
6489 self.expect(&token::OpenDelim(token::Brace))?;
6490 let mod_inner_lo = self.span;
6491 let attrs = self.parse_inner_attributes()?;
6492 let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
6494 self.directory = old_directory;
6495 Ok((id, ItemKind::Mod(module), Some(attrs)))
6499 fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
6500 if let Some(path) = attr::first_attr_value_str_by_name(attrs, sym::path) {
6501 self.directory.path.to_mut().push(&path.as_str());
6502 self.directory.ownership = DirectoryOwnership::Owned { relative: None };
6504 // We have to push on the current module name in the case of relative
6505 // paths in order to ensure that any additional module paths from inline
6506 // `mod x { ... }` come after the relative extension.
6508 // For example, a `mod z { ... }` inside `x/y.rs` should set the current
6509 // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
6510 if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
6511 if let Some(ident) = relative.take() { // remove the relative offset
6512 self.directory.path.to_mut().push(ident.as_str());
6515 self.directory.path.to_mut().push(&id.as_str());
6519 pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
6520 if let Some(s) = attr::first_attr_value_str_by_name(attrs, sym::path) {
6523 // On windows, the base path might have the form
6524 // `\\?\foo\bar` in which case it does not tolerate
6525 // mixed `/` and `\` separators, so canonicalize
6528 let s = s.replace("/", "\\");
6529 Some(dir_path.join(s))
6535 /// Returns a path to a module.
6536 pub fn default_submod_path(
6538 relative: Option<ast::Ident>,
6540 source_map: &SourceMap) -> ModulePath
6542 // If we're in a foo.rs file instead of a mod.rs file,
6543 // we need to look for submodules in
6544 // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
6545 // `./<id>.rs` and `./<id>/mod.rs`.
6546 let relative_prefix_string;
6547 let relative_prefix = if let Some(ident) = relative {
6548 relative_prefix_string = format!("{}{}", ident.as_str(), path::MAIN_SEPARATOR);
6549 &relative_prefix_string
6554 let mod_name = id.to_string();
6555 let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
6556 let secondary_path_str = format!("{}{}{}mod.rs",
6557 relative_prefix, mod_name, path::MAIN_SEPARATOR);
6558 let default_path = dir_path.join(&default_path_str);
6559 let secondary_path = dir_path.join(&secondary_path_str);
6560 let default_exists = source_map.file_exists(&default_path);
6561 let secondary_exists = source_map.file_exists(&secondary_path);
6563 let result = match (default_exists, secondary_exists) {
6564 (true, false) => Ok(ModulePathSuccess {
6566 directory_ownership: DirectoryOwnership::Owned {
6571 (false, true) => Ok(ModulePathSuccess {
6572 path: secondary_path,
6573 directory_ownership: DirectoryOwnership::Owned {
6578 (false, false) => Err(Error::FileNotFoundForModule {
6579 mod_name: mod_name.clone(),
6580 default_path: default_path_str,
6581 secondary_path: secondary_path_str,
6582 dir_path: dir_path.display().to_string(),
6584 (true, true) => Err(Error::DuplicatePaths {
6585 mod_name: mod_name.clone(),
6586 default_path: default_path_str,
6587 secondary_path: secondary_path_str,
6593 path_exists: default_exists || secondary_exists,
6598 fn submod_path(&mut self,
6600 outer_attrs: &[Attribute],
6602 -> PResult<'a, ModulePathSuccess> {
6603 if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
6604 return Ok(ModulePathSuccess {
6605 directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
6606 // All `#[path]` files are treated as though they are a `mod.rs` file.
6607 // This means that `mod foo;` declarations inside `#[path]`-included
6608 // files are siblings,
6610 // Note that this will produce weirdness when a file named `foo.rs` is
6611 // `#[path]` included and contains a `mod foo;` declaration.
6612 // If you encounter this, it's your own darn fault :P
6613 Some(_) => DirectoryOwnership::Owned { relative: None },
6614 _ => DirectoryOwnership::UnownedViaMod(true),
6621 let relative = match self.directory.ownership {
6622 DirectoryOwnership::Owned { relative } => relative,
6623 DirectoryOwnership::UnownedViaBlock |
6624 DirectoryOwnership::UnownedViaMod(_) => None,
6626 let paths = Parser::default_submod_path(
6627 id, relative, &self.directory.path, self.sess.source_map());
6629 match self.directory.ownership {
6630 DirectoryOwnership::Owned { .. } => {
6631 paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
6633 DirectoryOwnership::UnownedViaBlock => {
6635 "Cannot declare a non-inline module inside a block \
6636 unless it has a path attribute";
6637 let mut err = self.diagnostic().struct_span_err(id_sp, msg);
6638 if paths.path_exists {
6639 let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
6641 err.span_note(id_sp, &msg);
6645 DirectoryOwnership::UnownedViaMod(warn) => {
6647 if let Ok(result) = paths.result {
6648 return Ok(ModulePathSuccess { warn: true, ..result });
6651 let mut err = self.diagnostic().struct_span_err(id_sp,
6652 "cannot declare a new module at this location");
6653 if !id_sp.is_dummy() {
6654 let src_path = self.sess.source_map().span_to_filename(id_sp);
6655 if let FileName::Real(src_path) = src_path {
6656 if let Some(stem) = src_path.file_stem() {
6657 let mut dest_path = src_path.clone();
6658 dest_path.set_file_name(stem);
6659 dest_path.push("mod.rs");
6660 err.span_note(id_sp,
6661 &format!("maybe move this module `{}` to its own \
6662 directory via `{}`", src_path.display(),
6663 dest_path.display()));
6667 if paths.path_exists {
6668 err.span_note(id_sp,
6669 &format!("... or maybe `use` the module `{}` instead \
6670 of possibly redeclaring it",
6678 /// Reads a module from a source file.
6679 fn eval_src_mod(&mut self,
6681 directory_ownership: DirectoryOwnership,
6684 -> PResult<'a, (ast::Mod, Vec<Attribute> )> {
6685 let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
6686 if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
6687 let mut err = String::from("circular modules: ");
6688 let len = included_mod_stack.len();
6689 for p in &included_mod_stack[i.. len] {
6690 err.push_str(&p.to_string_lossy());
6691 err.push_str(" -> ");
6693 err.push_str(&path.to_string_lossy());
6694 return Err(self.span_fatal(id_sp, &err[..]));
6696 included_mod_stack.push(path.clone());
6697 drop(included_mod_stack);
6700 new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
6701 p0.cfg_mods = self.cfg_mods;
6702 let mod_inner_lo = p0.span;
6703 let mod_attrs = p0.parse_inner_attributes()?;
6704 let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
6706 self.sess.included_mod_stack.borrow_mut().pop();
6710 /// Parses a function declaration from a foreign module.
6711 fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6712 -> PResult<'a, ForeignItem> {
6713 self.expect_keyword(kw::Fn)?;
6715 let (ident, mut generics) = self.parse_fn_header()?;
6716 let decl = self.parse_fn_decl(true)?;
6717 generics.where_clause = self.parse_where_clause()?;
6719 self.expect(&token::Semi)?;
6720 Ok(ast::ForeignItem {
6723 node: ForeignItemKind::Fn(decl, generics),
6724 id: ast::DUMMY_NODE_ID,
6730 /// Parses a static item from a foreign module.
6731 /// Assumes that the `static` keyword is already parsed.
6732 fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6733 -> PResult<'a, ForeignItem> {
6734 let mutbl = self.parse_mutability();
6735 let ident = self.parse_ident()?;
6736 self.expect(&token::Colon)?;
6737 let ty = self.parse_ty()?;
6739 self.expect(&token::Semi)?;
6743 node: ForeignItemKind::Static(ty, mutbl),
6744 id: ast::DUMMY_NODE_ID,
6750 /// Parses a type from a foreign module.
6751 fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
6752 -> PResult<'a, ForeignItem> {
6753 self.expect_keyword(kw::Type)?;
6755 let ident = self.parse_ident()?;
6757 self.expect(&token::Semi)?;
6758 Ok(ast::ForeignItem {
6761 node: ForeignItemKind::Ty,
6762 id: ast::DUMMY_NODE_ID,
6768 fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
6769 let error_msg = "crate name using dashes are not valid in `extern crate` statements";
6770 let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
6772 let mut ident = if self.token.is_keyword(kw::SelfLower) {
6773 self.parse_path_segment_ident()
6777 let mut idents = vec![];
6778 let mut replacement = vec![];
6779 let mut fixed_crate_name = false;
6780 // Accept `extern crate name-like-this` for better diagnostics
6781 let dash = token::Token::BinOp(token::BinOpToken::Minus);
6782 if self.token == dash { // Do not include `-` as part of the expected tokens list
6783 while self.eat(&dash) {
6784 fixed_crate_name = true;
6785 replacement.push((self.prev_span, "_".to_string()));
6786 idents.push(self.parse_ident()?);
6789 if fixed_crate_name {
6790 let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
6791 let mut fixed_name = format!("{}", ident.name);
6792 for part in idents {
6793 fixed_name.push_str(&format!("_{}", part.name));
6795 ident = Ident::from_str(&fixed_name).with_span_pos(fixed_name_sp);
6797 let mut err = self.struct_span_err(fixed_name_sp, error_msg);
6798 err.span_label(fixed_name_sp, "dash-separated idents are not valid");
6799 err.multipart_suggestion(
6802 Applicability::MachineApplicable,
6809 /// Parses `extern crate` links.
6814 /// extern crate foo;
6815 /// extern crate bar as foo;
6817 fn parse_item_extern_crate(&mut self,
6819 visibility: Visibility,
6820 attrs: Vec<Attribute>)
6821 -> PResult<'a, P<Item>> {
6822 // Accept `extern crate name-like-this` for better diagnostics
6823 let orig_name = self.parse_crate_name_with_dashes()?;
6824 let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
6825 (rename, Some(orig_name.name))
6829 self.expect(&token::Semi)?;
6831 let span = lo.to(self.prev_span);
6832 Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
6835 /// Parses `extern` for foreign ABIs modules.
6837 /// `extern` is expected to have been
6838 /// consumed before calling this method.
6842 /// ```ignore (only-for-syntax-highlight)
6846 fn parse_item_foreign_mod(&mut self,
6848 opt_abi: Option<Abi>,
6849 visibility: Visibility,
6850 mut attrs: Vec<Attribute>)
6851 -> PResult<'a, P<Item>> {
6852 self.expect(&token::OpenDelim(token::Brace))?;
6854 let abi = opt_abi.unwrap_or(Abi::C);
6856 attrs.extend(self.parse_inner_attributes()?);
6858 let mut foreign_items = vec![];
6859 while !self.eat(&token::CloseDelim(token::Brace)) {
6860 foreign_items.push(self.parse_foreign_item()?);
6863 let prev_span = self.prev_span;
6864 let m = ast::ForeignMod {
6866 items: foreign_items
6868 let invalid = Ident::invalid();
6869 Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
6872 /// Parses `type Foo = Bar;`
6874 /// `existential type Foo: Bar;`
6877 /// without modifying the parser state.
6878 fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
6879 // This parses the grammar:
6880 // Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
6881 if self.check_keyword(kw::Type) ||
6882 self.check_keyword(kw::Existential) &&
6883 self.look_ahead(1, |t| t.is_keyword(kw::Type)) {
6884 let existential = self.eat_keyword(kw::Existential);
6885 assert!(self.eat_keyword(kw::Type));
6886 Some(self.parse_existential_or_alias(existential))
6892 /// Parses a type alias or existential type.
6893 fn parse_existential_or_alias(
6896 ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
6897 let ident = self.parse_ident()?;
6898 let mut tps = self.parse_generics()?;
6899 tps.where_clause = self.parse_where_clause()?;
6900 let alias = if existential {
6901 self.expect(&token::Colon)?;
6902 let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
6903 AliasKind::Existential(bounds)
6905 self.expect(&token::Eq)?;
6906 let ty = self.parse_ty()?;
6909 self.expect(&token::Semi)?;
6910 Ok((ident, alias, tps))
6913 /// Parses the part of an enum declaration following the `{`.
6914 fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
6915 let mut variants = Vec::new();
6916 let mut any_disr = vec![];
6917 while self.token != token::CloseDelim(token::Brace) {
6918 let variant_attrs = self.parse_outer_attributes()?;
6919 let vlo = self.span;
6922 let mut disr_expr = None;
6924 let ident = self.parse_ident()?;
6925 if self.check(&token::OpenDelim(token::Brace)) {
6926 // Parse a struct variant.
6927 let (fields, recovered) = self.parse_record_struct_body()?;
6928 struct_def = VariantData::Struct(fields, recovered);
6929 } else if self.check(&token::OpenDelim(token::Paren)) {
6930 struct_def = VariantData::Tuple(
6931 self.parse_tuple_struct_body()?,
6934 } else if self.eat(&token::Eq) {
6935 disr_expr = Some(AnonConst {
6936 id: ast::DUMMY_NODE_ID,
6937 value: self.parse_expr()?,
6939 if let Some(sp) = disr_expr.as_ref().map(|c| c.value.span) {
6942 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6944 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
6947 let vr = ast::Variant_ {
6949 id: ast::DUMMY_NODE_ID,
6950 attrs: variant_attrs,
6954 variants.push(respan(vlo.to(self.prev_span), vr));
6956 if !self.eat(&token::Comma) {
6957 if self.token.is_ident() && !self.token.is_reserved_ident() {
6958 let sp = self.sess.source_map().next_point(self.prev_span);
6959 let mut err = self.struct_span_err(sp, "missing comma");
6960 err.span_suggestion_short(
6964 Applicability::MaybeIncorrect,
6972 self.expect(&token::CloseDelim(token::Brace))?;
6973 self.maybe_report_invalid_custom_discriminants(any_disr, &variants);
6975 Ok(ast::EnumDef { variants })
6978 /// Parses an enum declaration.
6979 fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
6980 let id = self.parse_ident()?;
6981 let mut generics = self.parse_generics()?;
6982 generics.where_clause = self.parse_where_clause()?;
6983 self.expect(&token::OpenDelim(token::Brace))?;
6985 let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
6986 self.recover_stmt();
6987 self.eat(&token::CloseDelim(token::Brace));
6990 Ok((id, ItemKind::Enum(enum_definition, generics), None))
6993 /// Parses a string as an ABI spec on an extern type or module. Consumes
6994 /// the `extern` keyword, if one is found.
6995 fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
6997 token::Literal(token::Lit { kind: token::Str, symbol, suffix }) |
6998 token::Literal(token::Lit { kind: token::StrRaw(..), symbol, suffix }) => {
7000 self.expect_no_suffix(sp, "an ABI spec", suffix);
7002 match abi::lookup(&symbol.as_str()) {
7003 Some(abi) => Ok(Some(abi)),
7005 let prev_span = self.prev_span;
7006 let mut err = struct_span_err!(
7007 self.sess.span_diagnostic,
7010 "invalid ABI: found `{}`",
7012 err.span_label(prev_span, "invalid ABI");
7013 err.help(&format!("valid ABIs: {}", abi::all_names().join(", ")));
7024 fn is_static_global(&mut self) -> bool {
7025 if self.check_keyword(kw::Static) {
7026 // Check if this could be a closure
7027 !self.look_ahead(1, |token| {
7028 if token.is_keyword(kw::Move) {
7032 token::BinOp(token::Or) | token::OrOr => true,
7043 attrs: Vec<Attribute>,
7044 macros_allowed: bool,
7045 attributes_allowed: bool,
7046 ) -> PResult<'a, Option<P<Item>>> {
7047 let mut unclosed_delims = vec![];
7048 let (ret, tokens) = self.collect_tokens(|this| {
7049 let item = this.parse_item_implementation(attrs, macros_allowed, attributes_allowed);
7050 unclosed_delims.append(&mut this.unclosed_delims);
7053 self.unclosed_delims.append(&mut unclosed_delims);
7055 // Once we've parsed an item and recorded the tokens we got while
7056 // parsing we may want to store `tokens` into the item we're about to
7057 // return. Note, though, that we specifically didn't capture tokens
7058 // related to outer attributes. The `tokens` field here may later be
7059 // used with procedural macros to convert this item back into a token
7060 // stream, but during expansion we may be removing attributes as we go
7063 // If we've got inner attributes then the `tokens` we've got above holds
7064 // these inner attributes. If an inner attribute is expanded we won't
7065 // actually remove it from the token stream, so we'll just keep yielding
7066 // it (bad!). To work around this case for now we just avoid recording
7067 // `tokens` if we detect any inner attributes. This should help keep
7068 // expansion correct, but we should fix this bug one day!
7071 if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
7072 i.tokens = Some(tokens);
7079 /// Parses one of the items allowed by the flags.
7080 fn parse_item_implementation(
7082 attrs: Vec<Attribute>,
7083 macros_allowed: bool,
7084 attributes_allowed: bool,
7085 ) -> PResult<'a, Option<P<Item>>> {
7086 maybe_whole!(self, NtItem, |item| {
7087 let mut item = item.into_inner();
7088 let mut attrs = attrs;
7089 mem::swap(&mut item.attrs, &mut attrs);
7090 item.attrs.extend(attrs);
7096 let visibility = self.parse_visibility(false)?;
7098 if self.eat_keyword(kw::Use) {
7100 let item_ = ItemKind::Use(P(self.parse_use_tree()?));
7101 self.expect(&token::Semi)?;
7103 let span = lo.to(self.prev_span);
7105 self.mk_item(span, Ident::invalid(), item_, visibility, attrs);
7106 return Ok(Some(item));
7109 if self.eat_keyword(kw::Extern) {
7110 if self.eat_keyword(kw::Crate) {
7111 return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
7114 let opt_abi = self.parse_opt_abi()?;
7116 if self.eat_keyword(kw::Fn) {
7117 // EXTERN FUNCTION ITEM
7118 let fn_span = self.prev_span;
7119 let abi = opt_abi.unwrap_or(Abi::C);
7120 let (ident, item_, extra_attrs) =
7121 self.parse_item_fn(Unsafety::Normal,
7122 respan(fn_span, IsAsync::NotAsync),
7123 respan(fn_span, Constness::NotConst),
7125 let prev_span = self.prev_span;
7126 let item = self.mk_item(lo.to(prev_span),
7130 maybe_append(attrs, extra_attrs));
7131 return Ok(Some(item));
7132 } else if self.check(&token::OpenDelim(token::Brace)) {
7133 return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
7139 if self.is_static_global() {
7142 let m = if self.eat_keyword(kw::Mut) {
7145 Mutability::Immutable
7147 let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
7148 let prev_span = self.prev_span;
7149 let item = self.mk_item(lo.to(prev_span),
7153 maybe_append(attrs, extra_attrs));
7154 return Ok(Some(item));
7156 if self.eat_keyword(kw::Const) {
7157 let const_span = self.prev_span;
7158 if self.check_keyword(kw::Fn)
7159 || (self.check_keyword(kw::Unsafe)
7160 && self.look_ahead(1, |t| t.is_keyword(kw::Fn))) {
7161 // CONST FUNCTION ITEM
7162 let unsafety = self.parse_unsafety();
7164 let (ident, item_, extra_attrs) =
7165 self.parse_item_fn(unsafety,
7166 respan(const_span, IsAsync::NotAsync),
7167 respan(const_span, Constness::Const),
7169 let prev_span = self.prev_span;
7170 let item = self.mk_item(lo.to(prev_span),
7174 maybe_append(attrs, extra_attrs));
7175 return Ok(Some(item));
7179 if self.eat_keyword(kw::Mut) {
7180 let prev_span = self.prev_span;
7181 let mut err = self.diagnostic()
7182 .struct_span_err(prev_span, "const globals cannot be mutable");
7183 err.span_label(prev_span, "cannot be mutable");
7184 err.span_suggestion(
7186 "you might want to declare a static instead",
7187 "static".to_owned(),
7188 Applicability::MaybeIncorrect,
7192 let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
7193 let prev_span = self.prev_span;
7194 let item = self.mk_item(lo.to(prev_span),
7198 maybe_append(attrs, extra_attrs));
7199 return Ok(Some(item));
7202 // `unsafe async fn` or `async fn`
7204 self.check_keyword(kw::Unsafe) &&
7205 self.look_ahead(1, |t| t.is_keyword(kw::Async))
7207 self.check_keyword(kw::Async) &&
7208 self.look_ahead(1, |t| t.is_keyword(kw::Fn))
7211 // ASYNC FUNCTION ITEM
7212 let unsafety = self.parse_unsafety();
7213 self.expect_keyword(kw::Async)?;
7214 let async_span = self.prev_span;
7215 self.expect_keyword(kw::Fn)?;
7216 let fn_span = self.prev_span;
7217 let (ident, item_, extra_attrs) =
7218 self.parse_item_fn(unsafety,
7219 respan(async_span, IsAsync::Async {
7220 closure_id: ast::DUMMY_NODE_ID,
7221 return_impl_trait_id: ast::DUMMY_NODE_ID,
7222 arguments: Vec::new(),
7224 respan(fn_span, Constness::NotConst),
7226 let prev_span = self.prev_span;
7227 let item = self.mk_item(lo.to(prev_span),
7231 maybe_append(attrs, extra_attrs));
7232 if self.span.rust_2015() {
7233 self.diagnostic().struct_span_err_with_code(
7235 "`async fn` is not permitted in the 2015 edition",
7236 DiagnosticId::Error("E0670".into())
7239 return Ok(Some(item));
7241 if self.check_keyword(kw::Unsafe) &&
7242 (self.look_ahead(1, |t| t.is_keyword(kw::Trait)) ||
7243 self.look_ahead(1, |t| t.is_keyword(kw::Auto)))
7245 // UNSAFE TRAIT ITEM
7246 self.bump(); // `unsafe`
7247 let is_auto = if self.eat_keyword(kw::Trait) {
7250 self.expect_keyword(kw::Auto)?;
7251 self.expect_keyword(kw::Trait)?;
7254 let (ident, item_, extra_attrs) =
7255 self.parse_item_trait(is_auto, Unsafety::Unsafe)?;
7256 let prev_span = self.prev_span;
7257 let item = self.mk_item(lo.to(prev_span),
7261 maybe_append(attrs, extra_attrs));
7262 return Ok(Some(item));
7264 if self.check_keyword(kw::Impl) ||
7265 self.check_keyword(kw::Unsafe) &&
7266 self.look_ahead(1, |t| t.is_keyword(kw::Impl)) ||
7267 self.check_keyword(kw::Default) &&
7268 self.look_ahead(1, |t| t.is_keyword(kw::Impl)) ||
7269 self.check_keyword(kw::Default) &&
7270 self.look_ahead(1, |t| t.is_keyword(kw::Unsafe)) {
7272 let defaultness = self.parse_defaultness();
7273 let unsafety = self.parse_unsafety();
7274 self.expect_keyword(kw::Impl)?;
7275 let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?;
7276 let span = lo.to(self.prev_span);
7277 return Ok(Some(self.mk_item(span, ident, item, visibility,
7278 maybe_append(attrs, extra_attrs))));
7280 if self.check_keyword(kw::Fn) {
7283 let fn_span = self.prev_span;
7284 let (ident, item_, extra_attrs) =
7285 self.parse_item_fn(Unsafety::Normal,
7286 respan(fn_span, IsAsync::NotAsync),
7287 respan(fn_span, Constness::NotConst),
7289 let prev_span = self.prev_span;
7290 let item = self.mk_item(lo.to(prev_span),
7294 maybe_append(attrs, extra_attrs));
7295 return Ok(Some(item));
7297 if self.check_keyword(kw::Unsafe)
7298 && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
7299 // UNSAFE FUNCTION ITEM
7300 self.bump(); // `unsafe`
7301 // `{` is also expected after `unsafe`, in case of error, include it in the diagnostic
7302 self.check(&token::OpenDelim(token::Brace));
7303 let abi = if self.eat_keyword(kw::Extern) {
7304 self.parse_opt_abi()?.unwrap_or(Abi::C)
7308 self.expect_keyword(kw::Fn)?;
7309 let fn_span = self.prev_span;
7310 let (ident, item_, extra_attrs) =
7311 self.parse_item_fn(Unsafety::Unsafe,
7312 respan(fn_span, IsAsync::NotAsync),
7313 respan(fn_span, Constness::NotConst),
7315 let prev_span = self.prev_span;
7316 let item = self.mk_item(lo.to(prev_span),
7320 maybe_append(attrs, extra_attrs));
7321 return Ok(Some(item));
7323 if self.eat_keyword(kw::Mod) {
7325 let (ident, item_, extra_attrs) =
7326 self.parse_item_mod(&attrs[..])?;
7327 let prev_span = self.prev_span;
7328 let item = self.mk_item(lo.to(prev_span),
7332 maybe_append(attrs, extra_attrs));
7333 return Ok(Some(item));
7335 if let Some(type_) = self.eat_type() {
7336 let (ident, alias, generics) = type_?;
7338 let item_ = match alias {
7339 AliasKind::Weak(ty) => ItemKind::Ty(ty, generics),
7340 AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics),
7342 let prev_span = self.prev_span;
7343 let item = self.mk_item(lo.to(prev_span),
7348 return Ok(Some(item));
7350 if self.eat_keyword(kw::Enum) {
7352 let (ident, item_, extra_attrs) = self.parse_item_enum()?;
7353 let prev_span = self.prev_span;
7354 let item = self.mk_item(lo.to(prev_span),
7358 maybe_append(attrs, extra_attrs));
7359 return Ok(Some(item));
7361 if self.check_keyword(kw::Trait)
7362 || (self.check_keyword(kw::Auto)
7363 && self.look_ahead(1, |t| t.is_keyword(kw::Trait)))
7365 let is_auto = if self.eat_keyword(kw::Trait) {
7368 self.expect_keyword(kw::Auto)?;
7369 self.expect_keyword(kw::Trait)?;
7373 let (ident, item_, extra_attrs) =
7374 self.parse_item_trait(is_auto, Unsafety::Normal)?;
7375 let prev_span = self.prev_span;
7376 let item = self.mk_item(lo.to(prev_span),
7380 maybe_append(attrs, extra_attrs));
7381 return Ok(Some(item));
7383 if self.eat_keyword(kw::Struct) {
7385 let (ident, item_, extra_attrs) = self.parse_item_struct()?;
7386 let prev_span = self.prev_span;
7387 let item = self.mk_item(lo.to(prev_span),
7391 maybe_append(attrs, extra_attrs));
7392 return Ok(Some(item));
7394 if self.is_union_item() {
7397 let (ident, item_, extra_attrs) = self.parse_item_union()?;
7398 let prev_span = self.prev_span;
7399 let item = self.mk_item(lo.to(prev_span),
7403 maybe_append(attrs, extra_attrs));
7404 return Ok(Some(item));
7406 if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, lo)? {
7407 return Ok(Some(macro_def));
7410 // Verify whether we have encountered a struct or method definition where the user forgot to
7411 // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
7412 if visibility.node.is_pub() &&
7413 self.check_ident() &&
7414 self.look_ahead(1, |t| *t != token::Not)
7416 // Space between `pub` keyword and the identifier
7419 // ^^^ `sp` points here
7420 let sp = self.prev_span.between(self.span);
7421 let full_sp = self.prev_span.to(self.span);
7422 let ident_sp = self.span;
7423 if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
7424 // possible public struct definition where `struct` was forgotten
7425 let ident = self.parse_ident().unwrap();
7426 let msg = format!("add `struct` here to parse `{}` as a public struct",
7428 let mut err = self.diagnostic()
7429 .struct_span_err(sp, "missing `struct` for struct definition");
7430 err.span_suggestion_short(
7431 sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
7434 } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
7435 let ident = self.parse_ident().unwrap();
7437 let kw_name = if let Ok(Some(_)) = self.parse_self_arg() {
7442 self.consume_block(token::Paren);
7443 let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) {
7444 self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]);
7446 ("fn", kw_name, false)
7447 } else if self.check(&token::OpenDelim(token::Brace)) {
7449 ("fn", kw_name, false)
7450 } else if self.check(&token::Colon) {
7454 ("fn` or `struct", "function or struct", true)
7457 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7458 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7460 self.consume_block(token::Brace);
7461 let suggestion = format!("add `{}` here to parse `{}` as a public {}",
7465 err.span_suggestion_short(
7466 sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
7469 if let Ok(snippet) = self.sess.source_map().span_to_snippet(ident_sp) {
7470 err.span_suggestion(
7472 "if you meant to call a macro, try",
7473 format!("{}!", snippet),
7474 // this is the `ambiguous` conditional branch
7475 Applicability::MaybeIncorrect
7478 err.help("if you meant to call a macro, remove the `pub` \
7479 and add a trailing `!` after the identifier");
7483 } else if self.look_ahead(1, |t| *t == token::Lt) {
7484 let ident = self.parse_ident().unwrap();
7485 self.eat_to_tokens(&[&token::Gt]);
7487 let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) {
7488 if let Ok(Some(_)) = self.parse_self_arg() {
7489 ("fn", "method", false)
7491 ("fn", "function", false)
7493 } else if self.check(&token::OpenDelim(token::Brace)) {
7494 ("struct", "struct", false)
7496 ("fn` or `struct", "function or struct", true)
7498 let msg = format!("missing `{}` for {} definition", kw, kw_name);
7499 let mut err = self.diagnostic().struct_span_err(sp, &msg);
7501 err.span_suggestion_short(
7503 &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name),
7504 format!(" {} ", kw),
7505 Applicability::MachineApplicable,
7511 self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, visibility)
7514 /// Parses a foreign item.
7515 crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> {
7516 maybe_whole!(self, NtForeignItem, |ni| ni);
7518 let attrs = self.parse_outer_attributes()?;
7520 let visibility = self.parse_visibility(false)?;
7522 // FOREIGN STATIC ITEM
7523 // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
7524 if self.check_keyword(kw::Static) || self.token.is_keyword(kw::Const) {
7525 if self.token.is_keyword(kw::Const) {
7527 .struct_span_err(self.span, "extern items cannot be `const`")
7530 "try using a static value",
7531 "static".to_owned(),
7532 Applicability::MachineApplicable
7535 self.bump(); // `static` or `const`
7536 return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
7538 // FOREIGN FUNCTION ITEM
7539 if self.check_keyword(kw::Fn) {
7540 return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?);
7542 // FOREIGN TYPE ITEM
7543 if self.check_keyword(kw::Type) {
7544 return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
7547 match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
7551 ident: Ident::invalid(),
7552 span: lo.to(self.prev_span),
7553 id: ast::DUMMY_NODE_ID,
7556 node: ForeignItemKind::Macro(mac),
7561 if !attrs.is_empty() {
7562 self.expected_item_err(&attrs)?;
7570 /// This is the fall-through for parsing items.
7571 fn parse_macro_use_or_failure(
7573 attrs: Vec<Attribute> ,
7574 macros_allowed: bool,
7575 attributes_allowed: bool,
7577 visibility: Visibility
7578 ) -> PResult<'a, Option<P<Item>>> {
7579 if macros_allowed && self.token.is_path_start() &&
7580 !(self.is_async_fn() && self.span.rust_2015()) {
7581 // MACRO INVOCATION ITEM
7583 let prev_span = self.prev_span;
7584 self.complain_if_pub_macro(&visibility.node, prev_span);
7586 let mac_lo = self.span;
7589 let pth = self.parse_path(PathStyle::Mod)?;
7590 self.expect(&token::Not)?;
7592 // a 'special' identifier (like what `macro_rules!` uses)
7593 // is optional. We should eventually unify invoc syntax
7595 let id = if self.token.is_ident() {
7598 Ident::invalid() // no special identifier
7600 // eat a matched-delimiter token tree:
7601 let (delim, tts) = self.expect_delimited_token_tree()?;
7602 if delim != MacDelimiter::Brace && !self.eat(&token::Semi) {
7603 self.report_invalid_macro_expansion_item();
7606 let hi = self.prev_span;
7607 let mac = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim });
7608 let item = self.mk_item(lo.to(hi), id, ItemKind::Mac(mac), visibility, attrs);
7609 return Ok(Some(item));
7612 // FAILURE TO PARSE ITEM
7613 match visibility.node {
7614 VisibilityKind::Inherited => {}
7616 return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
7620 if !attributes_allowed && !attrs.is_empty() {
7621 self.expected_item_err(&attrs)?;
7626 /// Parses a macro invocation inside a `trait`, `impl` or `extern` block.
7627 fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
7628 at_end: &mut bool) -> PResult<'a, Option<Mac>>
7630 if self.token.is_path_start() &&
7631 !(self.is_async_fn() && self.span.rust_2015()) {
7632 let prev_span = self.prev_span;
7634 let pth = self.parse_path(PathStyle::Mod)?;
7636 if pth.segments.len() == 1 {
7637 if !self.eat(&token::Not) {
7638 return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
7641 self.expect(&token::Not)?;
7644 if let Some(vis) = vis {
7645 self.complain_if_pub_macro(&vis.node, prev_span);
7650 // eat a matched-delimiter token tree:
7651 let (delim, tts) = self.expect_delimited_token_tree()?;
7652 if delim != MacDelimiter::Brace {
7653 self.expect(&token::Semi)?;
7656 Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim })))
7662 fn collect_tokens<F, R>(&mut self, f: F) -> PResult<'a, (R, TokenStream)>
7663 where F: FnOnce(&mut Self) -> PResult<'a, R>
7665 // Record all tokens we parse when parsing this item.
7666 let mut tokens = Vec::new();
7667 let prev_collecting = match self.token_cursor.frame.last_token {
7668 LastToken::Collecting(ref mut list) => {
7669 Some(mem::replace(list, Vec::new()))
7671 LastToken::Was(ref mut last) => {
7672 tokens.extend(last.take());
7676 self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
7677 let prev = self.token_cursor.stack.len();
7679 let last_token = if self.token_cursor.stack.len() == prev {
7680 &mut self.token_cursor.frame.last_token
7682 &mut self.token_cursor.stack[prev].last_token
7685 // Pull out the tokens that we've collected from the call to `f` above.
7686 let mut collected_tokens = match *last_token {
7687 LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()),
7688 LastToken::Was(_) => panic!("our vector went away?"),
7691 // If we're not at EOF our current token wasn't actually consumed by
7692 // `f`, but it'll still be in our list that we pulled out. In that case
7694 let extra_token = if self.token != token::Eof {
7695 collected_tokens.pop()
7700 // If we were previously collecting tokens, then this was a recursive
7701 // call. In that case we need to record all the tokens we collected in
7702 // our parent list as well. To do that we push a clone of our stream
7703 // onto the previous list.
7704 match prev_collecting {
7706 list.extend(collected_tokens.iter().cloned());
7707 list.extend(extra_token);
7708 *last_token = LastToken::Collecting(list);
7711 *last_token = LastToken::Was(extra_token);
7715 Ok((ret?, TokenStream::new(collected_tokens)))
7718 pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
7719 let attrs = self.parse_outer_attributes()?;
7720 self.parse_item_(attrs, true, false)
7724 fn is_import_coupler(&mut self) -> bool {
7725 self.check(&token::ModSep) &&
7726 self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
7727 *t == token::BinOp(token::Star))
7730 /// Parses a `UseTree`.
7733 /// USE_TREE = [`::`] `*` |
7734 /// [`::`] `{` USE_TREE_LIST `}` |
7736 /// PATH `::` `{` USE_TREE_LIST `}` |
7737 /// PATH [`as` IDENT]
7739 fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
7742 let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
7743 let kind = if self.check(&token::OpenDelim(token::Brace)) ||
7744 self.check(&token::BinOp(token::Star)) ||
7745 self.is_import_coupler() {
7746 // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
7747 let mod_sep_ctxt = self.span.ctxt();
7748 if self.eat(&token::ModSep) {
7749 prefix.segments.push(
7750 PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
7754 if self.eat(&token::BinOp(token::Star)) {
7757 UseTreeKind::Nested(self.parse_use_tree_list()?)
7760 // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
7761 prefix = self.parse_path(PathStyle::Mod)?;
7763 if self.eat(&token::ModSep) {
7764 if self.eat(&token::BinOp(token::Star)) {
7767 UseTreeKind::Nested(self.parse_use_tree_list()?)
7770 UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID)
7774 Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
7777 /// Parses a `UseTreeKind::Nested(list)`.
7780 /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
7782 fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
7783 self.parse_unspanned_seq(&token::OpenDelim(token::Brace),
7784 &token::CloseDelim(token::Brace),
7785 SeqSep::trailing_allowed(token::Comma), |this| {
7786 Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID))
7790 fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
7791 if self.eat_keyword(kw::As) {
7792 self.parse_ident_or_underscore().map(Some)
7798 /// Parses a source module as a crate. This is the main entry point for the parser.
7799 pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
7801 let krate = Ok(ast::Crate {
7802 attrs: self.parse_inner_attributes()?,
7803 module: self.parse_mod_items(&token::Eof, lo)?,
7804 span: lo.to(self.span),
7809 pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
7810 let ret = match self.token {
7811 token::Literal(token::Lit { kind: token::Str, symbol, suffix }) =>
7812 (symbol, ast::StrStyle::Cooked, suffix),
7813 token::Literal(token::Lit { kind: token::StrRaw(n), symbol, suffix }) =>
7814 (symbol, ast::StrStyle::Raw(n), suffix),
7821 pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
7822 match self.parse_optional_str() {
7823 Some((s, style, suf)) => {
7824 let sp = self.prev_span;
7825 self.expect_no_suffix(sp, "a string literal", suf);
7829 let msg = "expected string literal";
7830 let mut err = self.fatal(msg);
7831 err.span_label(self.span, msg);
7837 fn report_invalid_macro_expansion_item(&self) {
7838 self.struct_span_err(
7840 "macros that expand to items must be delimited with braces or followed by a semicolon",
7841 ).multipart_suggestion(
7842 "change the delimiters to curly braces",
7844 (self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), String::from(" {")),
7845 (self.prev_span.with_lo(self.prev_span.hi() - BytePos(1)), '}'.to_string()),
7847 Applicability::MaybeIncorrect,
7849 self.sess.source_map.next_point(self.prev_span),
7852 Applicability::MaybeIncorrect,
7856 /// When lowering a `async fn` to the HIR, we need to move all of the arguments of the function
7857 /// into the generated closure so that they are dropped when the future is polled and not when
7860 /// The arguments of the function are replaced in HIR lowering with the arguments created by
7861 /// this function and the statements created here are inserted at the top of the closure body.
7862 fn construct_async_arguments(&mut self, asyncness: &mut Spanned<IsAsync>, decl: &mut FnDecl) {
7863 // FIXME(davidtwco): This function should really live in the HIR lowering but because
7864 // the types constructed here need to be used in parts of resolve so that the correct
7865 // locals are considered upvars, it is currently easier for it to live here in the parser,
7866 // where it can be constructed once.
7867 if let IsAsync::Async { ref mut arguments, .. } = asyncness.node {
7868 for (index, input) in decl.inputs.iter_mut().enumerate() {
7869 let id = ast::DUMMY_NODE_ID;
7870 let span = input.pat.span;
7871 let desugared_span = self.sess.source_map()
7872 .mark_span_with_reason(CompilerDesugaringKind::Async, span, None);
7874 // Construct a name for our temporary argument.
7875 let name = format!("__arg{}", index);
7876 let ident = Ident::from_str(&name).gensym();
7878 // Check if this is a ident pattern, if so, we can optimize and avoid adding a
7879 // `let <pat> = __argN;` statement, instead just adding a `let <pat> = <pat>;`
7881 let (binding_mode, ident, is_simple_pattern) = match input.pat.node {
7882 PatKind::Ident(binding_mode @ BindingMode::ByValue(_), ident, _) => {
7883 // Simple patterns like this don't have a generated argument, but they are
7884 // moved into the closure with a statement, so any `mut` bindings on the
7885 // argument will be unused. This binding mode can't be removed, because
7886 // this would affect the input to procedural macros, but they can have
7887 // their span marked as being the result of a compiler desugaring so
7888 // that they aren't linted against.
7889 input.pat.span = desugared_span;
7891 (binding_mode, ident, true)
7893 _ => (BindingMode::ByValue(Mutability::Mutable), ident, false),
7896 // Construct an argument representing `__argN: <ty>` to replace the argument of the
7897 // async function if it isn't a simple pattern.
7898 let arg = if is_simple_pattern {
7902 ty: input.ty.clone(),
7906 node: PatKind::Ident(
7907 BindingMode::ByValue(Mutability::Immutable), ident, None,
7909 span: desugared_span,
7911 source: ArgSource::AsyncFn(input.pat.clone()),
7915 // Construct a `let __argN = __argN;` statement to insert at the top of the
7916 // async closure. This makes sure that the argument is captured by the closure and
7917 // that the drop order is correct.
7918 let move_local = Local {
7921 node: PatKind::Ident(binding_mode, ident, None),
7922 span: desugared_span,
7924 // We explicitly do not specify the type for this statement. When the user's
7925 // argument type is `impl Trait` then this would require the
7926 // `impl_trait_in_bindings` feature to also be present for that same type to
7927 // be valid in this binding. At the time of writing (13 Mar 19),
7928 // `impl_trait_in_bindings` is not stable.
7932 node: ExprKind::Path(None, ast::Path {
7934 segments: vec![PathSegment { ident, id, args: None }],
7937 attrs: ThinVec::new(),
7941 attrs: ThinVec::new(),
7942 source: LocalSource::AsyncFn,
7945 // Construct a `let <pat> = __argN;` statement to insert at the top of the
7946 // async closure if this isn't a simple pattern.
7947 let pat_stmt = if is_simple_pattern {
7952 node: StmtKind::Local(P(Local {
7953 pat: input.pat.clone(),
7954 ..move_local.clone()
7960 let move_stmt = Stmt { id, node: StmtKind::Local(P(move_local)), span };
7961 arguments.push(AsyncArgument { ident, arg, pat_stmt, move_stmt });
7967 pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, handler: &errors::Handler) {
7968 for unmatched in unclosed_delims.iter() {
7969 let mut err = handler.struct_span_err(unmatched.found_span, &format!(
7970 "incorrect close delimiter: `{}`",
7971 pprust::token_to_string(&token::Token::CloseDelim(unmatched.found_delim)),
7973 err.span_label(unmatched.found_span, "incorrect close delimiter");
7974 if let Some(sp) = unmatched.candidate_span {
7975 err.span_label(sp, "close delimiter possibly meant for this");
7977 if let Some(sp) = unmatched.unclosed_span {
7978 err.span_label(sp, "un-closed delimiter");
7982 unclosed_delims.clear();