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Diffstat (limited to 'src/tools/rust-analyzer/bench_data/glorious_old_parser')
| -rw-r--r-- | src/tools/rust-analyzer/bench_data/glorious_old_parser | 8562 |
1 files changed, 8562 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/bench_data/glorious_old_parser b/src/tools/rust-analyzer/bench_data/glorious_old_parser new file mode 100644 index 000000000..7e900dfeb --- /dev/null +++ b/src/tools/rust-analyzer/bench_data/glorious_old_parser @@ -0,0 +1,8562 @@ +use crate::ast::{AngleBracketedArgs, ParenthesizedArgs, AttrStyle, BareFnTy}; +use crate::ast::{GenericBound, TraitBoundModifier}; +use crate::ast::Unsafety; +use crate::ast::{Mod, AnonConst, Arg, Arm, Guard, Attribute, BindingMode, TraitItemKind}; +use crate::ast::Block; +use crate::ast::{BlockCheckMode, CaptureBy, Movability}; +use crate::ast::{Constness, Crate}; +use crate::ast::Defaultness; +use crate::ast::EnumDef; +use crate::ast::{Expr, ExprKind, RangeLimits}; +use crate::ast::{Field, FnDecl, FnHeader}; +use crate::ast::{ForeignItem, ForeignItemKind, FunctionRetTy}; +use crate::ast::{GenericParam, GenericParamKind}; +use crate::ast::GenericArg; +use crate::ast::{Ident, ImplItem, IsAsync, IsAuto, Item, ItemKind}; +use crate::ast::{Label, Lifetime, Lit, LitKind}; +use crate::ast::Local; +use crate::ast::MacStmtStyle; +use crate::ast::{Mac, Mac_, MacDelimiter}; +use crate::ast::{MutTy, Mutability}; +use crate::ast::{Pat, PatKind, PathSegment}; +use crate::ast::{PolyTraitRef, QSelf}; +use crate::ast::{Stmt, StmtKind}; +use crate::ast::{VariantData, StructField}; +use crate::ast::StrStyle; +use crate::ast::SelfKind; +use crate::ast::{TraitItem, TraitRef, TraitObjectSyntax}; +use crate::ast::{Ty, TyKind, TypeBinding, GenericBounds}; +use crate::ast::{Visibility, VisibilityKind, WhereClause, CrateSugar}; +use crate::ast::{UseTree, UseTreeKind}; +use crate::ast::{BinOpKind, UnOp}; +use crate::ast::{RangeEnd, RangeSyntax}; +use crate::{ast, attr}; +use crate::ext::base::DummyResult; +use crate::source_map::{self, SourceMap, Spanned, respan}; +use crate::parse::{self, SeqSep, classify, token}; +use crate::parse::lexer::{TokenAndSpan, UnmatchedBrace}; +use crate::parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration}; +use crate::parse::token::DelimToken; +use crate::parse::{new_sub_parser_from_file, ParseSess, Directory, DirectoryOwnership}; +use crate::util::parser::{AssocOp, Fixity}; +use crate::print::pprust; +use crate::ptr::P; +use crate::parse::PResult; +use crate::ThinVec; +use crate::tokenstream::{self, DelimSpan, TokenTree, TokenStream, TreeAndJoint}; +use crate::symbol::{Symbol, keywords}; + +use errors::{Applicability, DiagnosticBuilder, DiagnosticId}; +use rustc_target::spec::abi::{self, Abi}; +use syntax_pos::{Span, MultiSpan, BytePos, FileName}; +use log::{debug, trace}; + +use std::borrow::Cow; +use std::cmp; +use std::mem; +use std::path::{self, Path, PathBuf}; +use std::slice; + +#[derive(Debug)] +/// Whether the type alias or associated type is a concrete type or an existential type +pub enum AliasKind { + /// Just a new name for the same type + Weak(P<Ty>), + /// Only trait impls of the type will be usable, not the actual type itself + Existential(GenericBounds), +} + +bitflags::bitflags! { + struct Restrictions: u8 { + const STMT_EXPR = 1 << 0; + const NO_STRUCT_LITERAL = 1 << 1; + } +} + +type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>); + +/// Specifies how to parse a path. +#[derive(Copy, Clone, PartialEq)] +pub enum PathStyle { + /// In some contexts, notably in expressions, paths with generic arguments are ambiguous + /// with something else. For example, in expressions `segment < ....` can be interpreted + /// as a comparison and `segment ( ....` can be interpreted as a function call. + /// In all such contexts the non-path interpretation is preferred by default for practical + /// reasons, but the path interpretation can be forced by the disambiguator `::`, e.g. + /// `x<y>` - comparisons, `x::<y>` - unambiguously a path. + Expr, + /// In other contexts, notably in types, no ambiguity exists and paths can be written + /// without the disambiguator, e.g., `x<y>` - unambiguously a path. + /// Paths with disambiguators are still accepted, `x::<Y>` - unambiguously a path too. + Type, + /// A path with generic arguments disallowed, e.g., `foo::bar::Baz`, used in imports, + /// visibilities or attributes. + /// Technically, this variant is unnecessary and e.g., `Expr` can be used instead + /// (paths in "mod" contexts have to be checked later for absence of generic arguments + /// anyway, due to macros), but it is used to avoid weird suggestions about expected + /// tokens when something goes wrong. + Mod, +} + +#[derive(Clone, Copy, PartialEq, Debug)] +enum SemiColonMode { + Break, + Ignore, + Comma, +} + +#[derive(Clone, Copy, PartialEq, Debug)] +enum BlockMode { + Break, + Ignore, +} + +/// Possibly accepts an `token::Interpolated` expression (a pre-parsed expression +/// dropped into the token stream, which happens while parsing the result of +/// macro expansion). Placement of these is not as complex as I feared it would +/// be. The important thing is to make sure that lookahead doesn't balk at +/// `token::Interpolated` tokens. +macro_rules! maybe_whole_expr { + ($p:expr) => { + if let token::Interpolated(nt) = $p.token.clone() { + match *nt { + token::NtExpr(ref e) | token::NtLiteral(ref e) => { + $p.bump(); + return Ok((*e).clone()); + } + token::NtPath(ref path) => { + $p.bump(); + let span = $p.span; + let kind = ExprKind::Path(None, (*path).clone()); + return Ok($p.mk_expr(span, kind, ThinVec::new())); + } + token::NtBlock(ref block) => { + $p.bump(); + let span = $p.span; + let kind = ExprKind::Block((*block).clone(), None); + return Ok($p.mk_expr(span, kind, ThinVec::new())); + } + _ => {}, + }; + } + } +} + +/// As maybe_whole_expr, but for things other than expressions +macro_rules! maybe_whole { + ($p:expr, $constructor:ident, |$x:ident| $e:expr) => { + if let token::Interpolated(nt) = $p.token.clone() { + if let token::$constructor($x) = (*nt).clone() { + $p.bump(); + return Ok($e); + } + } + }; +} + +fn maybe_append(mut lhs: Vec<Attribute>, mut rhs: Option<Vec<Attribute>>) -> Vec<Attribute> { + if let Some(ref mut rhs) = rhs { + lhs.append(rhs); + } + lhs +} + +#[derive(Debug, Clone, Copy, PartialEq)] +enum PrevTokenKind { + DocComment, + Comma, + Plus, + Interpolated, + Eof, + Ident, + Other, +} + +trait RecoverQPath: Sized { + const PATH_STYLE: PathStyle = PathStyle::Expr; + fn to_ty(&self) -> Option<P<Ty>>; + fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self; + fn to_string(&self) -> String; +} + +impl RecoverQPath for Ty { + const PATH_STYLE: PathStyle = PathStyle::Type; + fn to_ty(&self) -> Option<P<Ty>> { + Some(P(self.clone())) + } + fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self { + Self { span: path.span, node: TyKind::Path(qself, path), id: self.id } + } + fn to_string(&self) -> String { + pprust::ty_to_string(self) + } +} + +impl RecoverQPath for Pat { + fn to_ty(&self) -> Option<P<Ty>> { + self.to_ty() + } + fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self { + Self { span: path.span, node: PatKind::Path(qself, path), id: self.id } + } + fn to_string(&self) -> String { + pprust::pat_to_string(self) + } +} + +impl RecoverQPath for Expr { + fn to_ty(&self) -> Option<P<Ty>> { + self.to_ty() + } + fn to_recovered(&self, qself: Option<QSelf>, path: ast::Path) -> Self { + Self { span: path.span, node: ExprKind::Path(qself, path), + id: self.id, attrs: self.attrs.clone() } + } + fn to_string(&self) -> String { + pprust::expr_to_string(self) + } +} + +/* ident is handled by common.rs */ + +#[derive(Clone)] +pub struct Parser<'a> { + pub sess: &'a ParseSess, + /// the current token: + pub token: token::Token, + /// the span of the current token: + pub span: Span, + /// the span of the previous token: + meta_var_span: Option<Span>, + pub prev_span: Span, + /// the previous token kind + prev_token_kind: PrevTokenKind, + restrictions: Restrictions, + /// Used to determine the path to externally loaded source files + crate directory: Directory<'a>, + /// Whether to parse sub-modules in other files. + pub recurse_into_file_modules: bool, + /// Name of the root module this parser originated from. If `None`, then the + /// name is not known. This does not change while the parser is descending + /// into modules, and sub-parsers have new values for this name. + pub root_module_name: Option<String>, + crate expected_tokens: Vec<TokenType>, + token_cursor: TokenCursor, + desugar_doc_comments: bool, + /// Whether we should configure out of line modules as we parse. + pub cfg_mods: bool, + /// This field is used to keep track of how many left angle brackets we have seen. This is + /// required in order to detect extra leading left angle brackets (`<` characters) and error + /// appropriately. + /// + /// See the comments in the `parse_path_segment` function for more details. + crate unmatched_angle_bracket_count: u32, + crate max_angle_bracket_count: u32, + /// List of all unclosed delimiters found by the lexer. If an entry is used for error recovery + /// it gets removed from here. Every entry left at the end gets emitted as an independent + /// error. + crate unclosed_delims: Vec<UnmatchedBrace>, +} + + +#[derive(Clone)] +struct TokenCursor { + frame: TokenCursorFrame, + stack: Vec<TokenCursorFrame>, +} + +#[derive(Clone)] +struct TokenCursorFrame { + delim: token::DelimToken, + span: DelimSpan, + open_delim: bool, + tree_cursor: tokenstream::Cursor, + close_delim: bool, + last_token: LastToken, +} + +/// This is used in `TokenCursorFrame` above to track tokens that are consumed +/// by the parser, and then that's transitively used to record the tokens that +/// each parse AST item is created with. +/// +/// Right now this has two states, either collecting tokens or not collecting +/// tokens. If we're collecting tokens we just save everything off into a local +/// `Vec`. This should eventually though likely save tokens from the original +/// token stream and just use slicing of token streams to avoid creation of a +/// whole new vector. +/// +/// The second state is where we're passively not recording tokens, but the last +/// token is still tracked for when we want to start recording tokens. This +/// "last token" means that when we start recording tokens we'll want to ensure +/// that this, the first token, is included in the output. +/// +/// You can find some more example usage of this in the `collect_tokens` method +/// on the parser. +#[derive(Clone)] +enum LastToken { + Collecting(Vec<TreeAndJoint>), + Was(Option<TreeAndJoint>), +} + +impl TokenCursorFrame { + fn new(sp: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self { + TokenCursorFrame { + delim: delim, + span: sp, + open_delim: delim == token::NoDelim, + tree_cursor: tts.clone().into_trees(), + close_delim: delim == token::NoDelim, + last_token: LastToken::Was(None), + } + } +} + +impl TokenCursor { + fn next(&mut self) -> TokenAndSpan { + loop { + let tree = if !self.frame.open_delim { + self.frame.open_delim = true; + TokenTree::open_tt(self.frame.span.open, self.frame.delim) + } else if let Some(tree) = self.frame.tree_cursor.next() { + tree + } else if !self.frame.close_delim { + self.frame.close_delim = true; + TokenTree::close_tt(self.frame.span.close, self.frame.delim) + } else if let Some(frame) = self.stack.pop() { + self.frame = frame; + continue + } else { + return TokenAndSpan { tok: token::Eof, sp: syntax_pos::DUMMY_SP } + }; + + match self.frame.last_token { + LastToken::Collecting(ref mut v) => v.push(tree.clone().into()), + LastToken::Was(ref mut t) => *t = Some(tree.clone().into()), + } + + match tree { + TokenTree::Token(sp, tok) => return TokenAndSpan { tok: tok, sp: sp }, + TokenTree::Delimited(sp, delim, tts) => { + let frame = TokenCursorFrame::new(sp, delim, &tts); + self.stack.push(mem::replace(&mut self.frame, frame)); + } + } + } + } + + fn next_desugared(&mut self) -> TokenAndSpan { + let (sp, name) = match self.next() { + TokenAndSpan { sp, tok: token::DocComment(name) } => (sp, name), + tok => return tok, + }; + + let stripped = strip_doc_comment_decoration(&name.as_str()); + + // Searches for the occurrences of `"#*` and returns the minimum number of `#`s + // required to wrap the text. + let mut num_of_hashes = 0; + let mut count = 0; + for ch in stripped.chars() { + count = match ch { + '"' => 1, + '#' if count > 0 => count + 1, + _ => 0, + }; + num_of_hashes = cmp::max(num_of_hashes, count); + } + + let delim_span = DelimSpan::from_single(sp); + let body = TokenTree::Delimited( + delim_span, + token::Bracket, + [TokenTree::Token(sp, token::Ident(ast::Ident::from_str("doc"), false)), + TokenTree::Token(sp, token::Eq), + TokenTree::Token(sp, token::Literal( + token::StrRaw(Symbol::intern(&stripped), num_of_hashes), None)) + ] + .iter().cloned().collect::<TokenStream>().into(), + ); + + self.stack.push(mem::replace(&mut self.frame, TokenCursorFrame::new( + delim_span, + token::NoDelim, + &if doc_comment_style(&name.as_str()) == AttrStyle::Inner { + [TokenTree::Token(sp, token::Pound), TokenTree::Token(sp, token::Not), body] + .iter().cloned().collect::<TokenStream>().into() + } else { + [TokenTree::Token(sp, token::Pound), body] + .iter().cloned().collect::<TokenStream>().into() + }, + ))); + + self.next() + } +} + +#[derive(Clone, PartialEq)] +crate enum TokenType { + Token(token::Token), + Keyword(keywords::Keyword), + Operator, + Lifetime, + Ident, + Path, + Type, + Const, +} + +impl TokenType { + fn to_string(&self) -> String { + match *self { + TokenType::Token(ref t) => format!("`{}`", pprust::token_to_string(t)), + TokenType::Keyword(kw) => format!("`{}`", kw.name()), + TokenType::Operator => "an operator".to_string(), + TokenType::Lifetime => "lifetime".to_string(), + TokenType::Ident => "identifier".to_string(), + TokenType::Path => "path".to_string(), + TokenType::Type => "type".to_string(), + TokenType::Const => "const".to_string(), + } + } +} + +/// Returns `true` if `IDENT t` can start a type -- `IDENT::a::b`, `IDENT<u8, u8>`, +/// `IDENT<<u8 as Trait>::AssocTy>`. +/// +/// Types can also be of the form `IDENT(u8, u8) -> u8`, however this assumes +/// that `IDENT` is not the ident of a fn trait. +fn can_continue_type_after_non_fn_ident(t: &token::Token) -> bool { + t == &token::ModSep || t == &token::Lt || + t == &token::BinOp(token::Shl) +} + +/// Information about the path to a module. +pub struct ModulePath { + name: String, + path_exists: bool, + pub result: Result<ModulePathSuccess, Error>, +} + +pub struct ModulePathSuccess { + pub path: PathBuf, + pub directory_ownership: DirectoryOwnership, + warn: bool, +} + +pub enum Error { + FileNotFoundForModule { + mod_name: String, + default_path: String, + secondary_path: String, + dir_path: String, + }, + DuplicatePaths { + mod_name: String, + default_path: String, + secondary_path: String, + }, + UselessDocComment, + InclusiveRangeWithNoEnd, +} + +impl Error { + fn span_err<S: Into<MultiSpan>>(self, + sp: S, + handler: &errors::Handler) -> DiagnosticBuilder<'_> { + match self { + Error::FileNotFoundForModule { ref mod_name, + ref default_path, + ref secondary_path, + ref dir_path } => { + let mut err = struct_span_err!(handler, sp, E0583, + "file not found for module `{}`", mod_name); + err.help(&format!("name the file either {} or {} inside the directory \"{}\"", + default_path, + secondary_path, + dir_path)); + err + } + Error::DuplicatePaths { ref mod_name, ref default_path, ref secondary_path } => { + let mut err = struct_span_err!(handler, sp, E0584, + "file for module `{}` found at both {} and {}", + mod_name, + default_path, + secondary_path); + err.help("delete or rename one of them to remove the ambiguity"); + err + } + Error::UselessDocComment => { + let mut err = struct_span_err!(handler, sp, E0585, + "found a documentation comment that doesn't document anything"); + err.help("doc comments must come before what they document, maybe a comment was \ + intended with `//`?"); + err + } + Error::InclusiveRangeWithNoEnd => { + let mut err = struct_span_err!(handler, sp, E0586, + "inclusive range with no end"); + err.help("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)"); + err + } + } + } +} + +#[derive(Debug)] +enum LhsExpr { + NotYetParsed, + AttributesParsed(ThinVec<Attribute>), + AlreadyParsed(P<Expr>), +} + +impl From<Option<ThinVec<Attribute>>> for LhsExpr { + fn from(o: Option<ThinVec<Attribute>>) -> Self { + if let Some(attrs) = o { + LhsExpr::AttributesParsed(attrs) + } else { + LhsExpr::NotYetParsed + } + } +} + +impl From<P<Expr>> for LhsExpr { + fn from(expr: P<Expr>) -> Self { + LhsExpr::AlreadyParsed(expr) + } +} + +/// Creates a placeholder argument. +fn dummy_arg(span: Span) -> Arg { + let ident = Ident::new(keywords::Invalid.name(), span); + let pat = P(Pat { + id: ast::DUMMY_NODE_ID, + node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), ident, None), + span, + }); + let ty = Ty { + node: TyKind::Err, + span, + id: ast::DUMMY_NODE_ID + }; + Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID } +} + +#[derive(Copy, Clone, Debug)] +enum TokenExpectType { + Expect, + NoExpect, +} + +impl<'a> Parser<'a> { + pub fn new(sess: &'a ParseSess, + tokens: TokenStream, + directory: Option<Directory<'a>>, + recurse_into_file_modules: bool, + desugar_doc_comments: bool) + -> Self { + let mut parser = Parser { + sess, + token: token::Whitespace, + span: syntax_pos::DUMMY_SP, + prev_span: syntax_pos::DUMMY_SP, + meta_var_span: None, + prev_token_kind: PrevTokenKind::Other, + restrictions: Restrictions::empty(), + recurse_into_file_modules, + directory: Directory { + path: Cow::from(PathBuf::new()), + ownership: DirectoryOwnership::Owned { relative: None } + }, + root_module_name: None, + expected_tokens: Vec::new(), + token_cursor: TokenCursor { + frame: TokenCursorFrame::new( + DelimSpan::dummy(), + token::NoDelim, + &tokens.into(), + ), + stack: Vec::new(), + }, + desugar_doc_comments, + cfg_mods: true, + unmatched_angle_bracket_count: 0, + max_angle_bracket_count: 0, + unclosed_delims: Vec::new(), + }; + + let tok = parser.next_tok(); + parser.token = tok.tok; + parser.span = tok.sp; + + if let Some(directory) = directory { + parser.directory = directory; + } else if !parser.span.is_dummy() { + if let FileName::Real(mut path) = sess.source_map().span_to_unmapped_path(parser.span) { + path.pop(); + parser.directory.path = Cow::from(path); + } + } + + parser.process_potential_macro_variable(); + parser + } + + fn next_tok(&mut self) -> TokenAndSpan { + let mut next = if self.desugar_doc_comments { + self.token_cursor.next_desugared() + } else { + self.token_cursor.next() + }; + if next.sp.is_dummy() { + // Tweak the location for better diagnostics, but keep syntactic context intact. + next.sp = self.prev_span.with_ctxt(next.sp.ctxt()); + } + next + } + + /// Converts the current token to a string using `self`'s reader. + pub fn this_token_to_string(&self) -> String { + pprust::token_to_string(&self.token) + } + + fn token_descr(&self) -> Option<&'static str> { + Some(match &self.token { + t if t.is_special_ident() => "reserved identifier", + t if t.is_used_keyword() => "keyword", + t if t.is_unused_keyword() => "reserved keyword", + token::DocComment(..) => "doc comment", + _ => return None, + }) + } + + fn this_token_descr(&self) -> String { + if let Some(prefix) = self.token_descr() { + format!("{} `{}`", prefix, self.this_token_to_string()) + } else { + format!("`{}`", self.this_token_to_string()) + } + } + + fn unexpected_last<T>(&self, t: &token::Token) -> PResult<'a, T> { + let token_str = pprust::token_to_string(t); + Err(self.span_fatal(self.prev_span, &format!("unexpected token: `{}`", token_str))) + } + + crate fn unexpected<T>(&mut self) -> PResult<'a, T> { + match self.expect_one_of(&[], &[]) { + Err(e) => Err(e), + Ok(_) => unreachable!(), + } + } + + /// Expects and consumes the token `t`. Signals an error if the next token is not `t`. + pub fn expect(&mut self, t: &token::Token) -> PResult<'a, bool /* recovered */> { + if self.expected_tokens.is_empty() { + if self.token == *t { + self.bump(); + Ok(false) + } else { + let token_str = pprust::token_to_string(t); + let this_token_str = self.this_token_descr(); + let mut err = self.fatal(&format!("expected `{}`, found {}", + token_str, + this_token_str)); + + let sp = if self.token == token::Token::Eof { + // EOF, don't want to point at the following char, but rather the last token + self.prev_span + } else { + self.sess.source_map().next_point(self.prev_span) + }; + let label_exp = format!("expected `{}`", token_str); + match self.recover_closing_delimiter(&[t.clone()], err) { + Err(e) => err = e, + Ok(recovered) => { + return Ok(recovered); + } + } + let cm = self.sess.source_map(); + match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) { + (Ok(ref a), Ok(ref b)) if a.line == b.line => { + // When the spans are in the same line, it means that the only content + // between them is whitespace, point only at the found token. + err.span_label(self.span, label_exp); + } + _ => { + err.span_label(sp, label_exp); + err.span_label(self.span, "unexpected token"); + } + } + Err(err) + } + } else { + self.expect_one_of(slice::from_ref(t), &[]) + } + } + + fn recover_closing_delimiter( + &mut self, + tokens: &[token::Token], + mut err: DiagnosticBuilder<'a>, + ) -> PResult<'a, bool> { + let mut pos = None; + // we want to use the last closing delim that would apply + for (i, unmatched) in self.unclosed_delims.iter().enumerate().rev() { + if tokens.contains(&token::CloseDelim(unmatched.expected_delim)) + && Some(self.span) > unmatched.unclosed_span + { + pos = Some(i); + } + } + match pos { + Some(pos) => { + // Recover and assume that the detected unclosed delimiter was meant for + // this location. Emit the diagnostic and act as if the delimiter was + // present for the parser's sake. + + // Don't attempt to recover from this unclosed delimiter more than once. + let unmatched = self.unclosed_delims.remove(pos); + let delim = TokenType::Token(token::CloseDelim(unmatched.expected_delim)); + + // We want to suggest the inclusion of the closing delimiter where it makes + // the most sense, which is immediately after the last token: + // + // {foo(bar {}} + // - ^ + // | | + // | help: `)` may belong here (FIXME: #58270) + // | + // unclosed delimiter + if let Some(sp) = unmatched.unclosed_span { + err.span_label(sp, "unclosed delimiter"); + } + err.span_suggestion_short( + self.sess.source_map().next_point(self.prev_span), + &format!("{} may belong here", delim.to_string()), + delim.to_string(), + Applicability::MaybeIncorrect, + ); + err.emit(); + self.expected_tokens.clear(); // reduce errors + Ok(true) + } + _ => Err(err), + } + } + + /// Expect next token to be edible or inedible token. If edible, + /// then consume it; if inedible, then return without consuming + /// anything. Signal a fatal error if next token is unexpected. + pub fn expect_one_of( + &mut self, + edible: &[token::Token], + inedible: &[token::Token], + ) -> PResult<'a, bool /* recovered */> { + fn tokens_to_string(tokens: &[TokenType]) -> String { + let mut i = tokens.iter(); + // This might be a sign we need a connect method on Iterator. + let b = i.next() + .map_or(String::new(), |t| t.to_string()); + i.enumerate().fold(b, |mut b, (i, a)| { + if tokens.len() > 2 && i == tokens.len() - 2 { + b.push_str(", or "); + } else if tokens.len() == 2 && i == tokens.len() - 2 { + b.push_str(" or "); + } else { + b.push_str(", "); + } + b.push_str(&a.to_string()); + b + }) + } + if edible.contains(&self.token) { + self.bump(); + Ok(false) + } else if inedible.contains(&self.token) { + // leave it in the input + Ok(false) + } else { + let mut expected = edible.iter() + .map(|x| TokenType::Token(x.clone())) + .chain(inedible.iter().map(|x| TokenType::Token(x.clone()))) + .chain(self.expected_tokens.iter().cloned()) + .collect::<Vec<_>>(); + expected.sort_by_cached_key(|x| x.to_string()); + expected.dedup(); + let expect = tokens_to_string(&expected[..]); + let actual = self.this_token_to_string(); + let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 { + let short_expect = if expected.len() > 6 { + format!("{} possible tokens", expected.len()) + } else { + expect.clone() + }; + (format!("expected one of {}, found `{}`", expect, actual), + (self.sess.source_map().next_point(self.prev_span), + format!("expected one of {} here", short_expect))) + } else if expected.is_empty() { + (format!("unexpected token: `{}`", actual), + (self.prev_span, "unexpected token after this".to_string())) + } else { + (format!("expected {}, found `{}`", expect, actual), + (self.sess.source_map().next_point(self.prev_span), + format!("expected {} here", expect))) + }; + let mut err = self.fatal(&msg_exp); + if self.token.is_ident_named("and") { + err.span_suggestion_short( + self.span, + "use `&&` instead of `and` for the boolean operator", + "&&".to_string(), + Applicability::MaybeIncorrect, + ); + } + if self.token.is_ident_named("or") { + err.span_suggestion_short( + self.span, + "use `||` instead of `or` for the boolean operator", + "||".to_string(), + Applicability::MaybeIncorrect, + ); + } + let sp = if self.token == token::Token::Eof { + // This is EOF, don't want to point at the following char, but rather the last token + self.prev_span + } else { + label_sp + }; + match self.recover_closing_delimiter(&expected.iter().filter_map(|tt| match tt { + TokenType::Token(t) => Some(t.clone()), + _ => None, + }).collect::<Vec<_>>(), err) { + Err(e) => err = e, + Ok(recovered) => { + return Ok(recovered); + } + } + + let cm = self.sess.source_map(); + match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) { + (Ok(ref a), Ok(ref b)) if a.line == b.line => { + // When the spans are in the same line, it means that the only content between + // them is whitespace, point at the found token in that case: + // + // X | () => { syntax error }; + // | ^^^^^ expected one of 8 possible tokens here + // + // instead of having: + // + // X | () => { syntax error }; + // | -^^^^^ unexpected token + // | | + // | expected one of 8 possible tokens here + err.span_label(self.span, label_exp); + } + _ if self.prev_span == syntax_pos::DUMMY_SP => { + // Account for macro context where the previous span might not be + // available to avoid incorrect output (#54841). + err.span_label(self.span, "unexpected token"); + } + _ => { + err.span_label(sp, label_exp); + err.span_label(self.span, "unexpected token"); + } + } + Err(err) + } + } + + /// Returns the span of expr, if it was not interpolated or the span of the interpolated token. + fn interpolated_or_expr_span(&self, + expr: PResult<'a, P<Expr>>) + -> PResult<'a, (Span, P<Expr>)> { + expr.map(|e| { + if self.prev_token_kind == PrevTokenKind::Interpolated { + (self.prev_span, e) + } else { + (e.span, e) + } + }) + } + + fn expected_ident_found(&self) -> DiagnosticBuilder<'a> { + let mut err = self.struct_span_err(self.span, + &format!("expected identifier, found {}", + self.this_token_descr())); + if let token::Ident(ident, false) = &self.token { + if ident.is_reserved() && !ident.is_path_segment_keyword() && + ident.name != keywords::Underscore.name() + { + err.span_suggestion( + self.span, + "you can escape reserved keywords to use them as identifiers", + format!("r#{}", ident), + Applicability::MaybeIncorrect, + ); + } + } + if let Some(token_descr) = self.token_descr() { + err.span_label(self.span, format!("expected identifier, found {}", token_descr)); + } else { + err.span_label(self.span, "expected identifier"); + if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) { + err.span_suggestion( + self.span, + "remove this comma", + String::new(), + Applicability::MachineApplicable, + ); + } + } + err + } + + pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> { + self.parse_ident_common(true) + } + + fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> { + match self.token { + token::Ident(ident, _) => { + if self.token.is_reserved_ident() { + let mut err = self.expected_ident_found(); + if recover { + err.emit(); + } else { + return Err(err); + } + } + let span = self.span; + self.bump(); + Ok(Ident::new(ident.name, span)) + } + _ => { + Err(if self.prev_token_kind == PrevTokenKind::DocComment { + self.span_fatal_err(self.prev_span, Error::UselessDocComment) + } else { + self.expected_ident_found() + }) + } + } + } + + /// Checks if the next token is `tok`, and returns `true` if so. + /// + /// This method will automatically add `tok` to `expected_tokens` if `tok` is not + /// encountered. + crate fn check(&mut self, tok: &token::Token) -> bool { + let is_present = self.token == *tok; + if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); } + is_present + } + + /// Consumes a token 'tok' if it exists. Returns whether the given token was present. + pub fn eat(&mut self, tok: &token::Token) -> bool { + let is_present = self.check(tok); + if is_present { self.bump() } + is_present + } + + fn check_keyword(&mut self, kw: keywords::Keyword) -> bool { + self.expected_tokens.push(TokenType::Keyword(kw)); + self.token.is_keyword(kw) + } + + /// If the next token is the given keyword, eats it and returns + /// `true`. Otherwise, returns `false`. + pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool { + if self.check_keyword(kw) { + self.bump(); + true + } else { + false + } + } + + fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool { + if self.token.is_keyword(kw) { + self.bump(); + true + } else { + false + } + } + + /// If the given word is not a keyword, signals an error. + /// If the next token is not the given word, signals an error. + /// Otherwise, eats it. + fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> { + if !self.eat_keyword(kw) { + self.unexpected() + } else { + Ok(()) + } + } + + fn check_ident(&mut self) -> bool { + if self.token.is_ident() { + true + } else { + self.expected_tokens.push(TokenType::Ident); + false + } + } + + fn check_path(&mut self) -> bool { + if self.token.is_path_start() { + true + } else { + self.expected_tokens.push(TokenType::Path); + false + } + } + + fn check_type(&mut self) -> bool { + if self.token.can_begin_type() { + true + } else { + self.expected_tokens.push(TokenType::Type); + false + } + } + + fn check_const_arg(&mut self) -> bool { + if self.token.can_begin_const_arg() { + true + } else { + self.expected_tokens.push(TokenType::Const); + false + } + } + + /// Expects and consumes a `+`. if `+=` is seen, replaces it with a `=` + /// and continues. If a `+` is not seen, returns `false`. + /// + /// This is used when token-splitting `+=` into `+`. + /// See issue #47856 for an example of when this may occur. + fn eat_plus(&mut self) -> bool { + self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus))); + match self.token { + token::BinOp(token::Plus) => { + self.bump(); + true + } + token::BinOpEq(token::Plus) => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + self.bump_with(token::Eq, span); + true + } + _ => false, + } + } + + + /// Checks to see if the next token is either `+` or `+=`. + /// Otherwise returns `false`. + fn check_plus(&mut self) -> bool { + if self.token.is_like_plus() { + true + } + else { + self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus))); + false + } + } + + /// Expects and consumes an `&`. If `&&` is seen, replaces it with a single + /// `&` and continues. If an `&` is not seen, signals an error. + fn expect_and(&mut self) -> PResult<'a, ()> { + self.expected_tokens.push(TokenType::Token(token::BinOp(token::And))); + match self.token { + token::BinOp(token::And) => { + self.bump(); + Ok(()) + } + token::AndAnd => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + Ok(self.bump_with(token::BinOp(token::And), span)) + } + _ => self.unexpected() + } + } + + /// Expects and consumes an `|`. If `||` is seen, replaces it with a single + /// `|` and continues. If an `|` is not seen, signals an error. + fn expect_or(&mut self) -> PResult<'a, ()> { + self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or))); + match self.token { + token::BinOp(token::Or) => { + self.bump(); + Ok(()) + } + token::OrOr => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + Ok(self.bump_with(token::BinOp(token::Or), span)) + } + _ => self.unexpected() + } + } + + fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) { + match suffix { + None => {/* everything ok */} + Some(suf) => { + let text = suf.as_str(); + if text.is_empty() { + self.span_bug(sp, "found empty literal suffix in Some") + } + let msg = format!("{} with a suffix is invalid", kind); + self.struct_span_err(sp, &msg) + .span_label(sp, msg) + .emit(); + } + } + } + + /// Attempts to consume a `<`. If `<<` is seen, replaces it with a single + /// `<` and continue. If `<-` is seen, replaces it with a single `<` + /// and continue. If a `<` is not seen, returns false. + /// + /// This is meant to be used when parsing generics on a path to get the + /// starting token. + fn eat_lt(&mut self) -> bool { + self.expected_tokens.push(TokenType::Token(token::Lt)); + let ate = match self.token { + token::Lt => { + self.bump(); + true + } + token::BinOp(token::Shl) => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + self.bump_with(token::Lt, span); + true + } + token::LArrow => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + self.bump_with(token::BinOp(token::Minus), span); + true + } + _ => false, + }; + + if ate { + // See doc comment for `unmatched_angle_bracket_count`. + self.unmatched_angle_bracket_count += 1; + self.max_angle_bracket_count += 1; + debug!("eat_lt: (increment) count={:?}", self.unmatched_angle_bracket_count); + } + + ate + } + + fn expect_lt(&mut self) -> PResult<'a, ()> { + if !self.eat_lt() { + self.unexpected() + } else { + Ok(()) + } + } + + /// Expects and consumes a single `>` token. if a `>>` is seen, replaces it + /// with a single `>` and continues. If a `>` is not seen, signals an error. + fn expect_gt(&mut self) -> PResult<'a, ()> { + self.expected_tokens.push(TokenType::Token(token::Gt)); + let ate = match self.token { + token::Gt => { + self.bump(); + Some(()) + } + token::BinOp(token::Shr) => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + Some(self.bump_with(token::Gt, span)) + } + token::BinOpEq(token::Shr) => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + Some(self.bump_with(token::Ge, span)) + } + token::Ge => { + let span = self.span.with_lo(self.span.lo() + BytePos(1)); + Some(self.bump_with(token::Eq, span)) + } + _ => None, + }; + + match ate { + Some(_) => { + // See doc comment for `unmatched_angle_bracket_count`. + if self.unmatched_angle_bracket_count > 0 { + self.unmatched_angle_bracket_count -= 1; + debug!("expect_gt: (decrement) count={:?}", self.unmatched_angle_bracket_count); + } + + Ok(()) + }, + None => self.unexpected(), + } + } + + /// Eats and discards tokens until one of `kets` is encountered. Respects token trees, + /// passes through any errors encountered. Used for error recovery. + fn eat_to_tokens(&mut self, kets: &[&token::Token]) { + let handler = self.diagnostic(); + + if let Err(ref mut err) = self.parse_seq_to_before_tokens(kets, + SeqSep::none(), + TokenExpectType::Expect, + |p| Ok(p.parse_token_tree())) { + handler.cancel(err); + } + } + + /// Parses a sequence, including the closing delimiter. The function + /// `f` must consume tokens until reaching the next separator or + /// closing bracket. + pub fn parse_seq_to_end<T, F>(&mut self, + ket: &token::Token, + sep: SeqSep, + f: F) + -> PResult<'a, Vec<T>> where + F: FnMut(&mut Parser<'a>) -> PResult<'a, T>, + { + let (val, recovered) = self.parse_seq_to_before_end(ket, sep, f)?; + if !recovered { + self.bump(); + } + Ok(val) + } + + /// Parses a sequence, not including the closing delimiter. The function + /// `f` must consume tokens until reaching the next separator or + /// closing bracket. + pub fn parse_seq_to_before_end<T, F>( + &mut self, + ket: &token::Token, + sep: SeqSep, + f: F, + ) -> PResult<'a, (Vec<T>, bool)> + where F: FnMut(&mut Parser<'a>) -> PResult<'a, T> + { + self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f) + } + + fn parse_seq_to_before_tokens<T, F>( + &mut self, + kets: &[&token::Token], + sep: SeqSep, + expect: TokenExpectType, + mut f: F, + ) -> PResult<'a, (Vec<T>, bool /* recovered */)> + where F: FnMut(&mut Parser<'a>) -> PResult<'a, T> + { + let mut first = true; + let mut recovered = false; + let mut v = vec![]; + while !kets.iter().any(|k| { + match expect { + TokenExpectType::Expect => self.check(k), + TokenExpectType::NoExpect => self.token == **k, + } + }) { + match self.token { + token::CloseDelim(..) | token::Eof => break, + _ => {} + }; + if let Some(ref t) = sep.sep { + if first { + first = false; + } else { + match self.expect(t) { + Ok(false) => {} + Ok(true) => { + recovered = true; + break; + } + Err(mut e) => { + // Attempt to keep parsing if it was a similar separator + if let Some(ref tokens) = t.similar_tokens() { + if tokens.contains(&self.token) { + self.bump(); + } + } + e.emit(); + // Attempt to keep parsing if it was an omitted separator + match f(self) { + Ok(t) => { + v.push(t); + continue; + }, + Err(mut e) => { + e.cancel(); + break; + } + } + } + } + } + } + if sep.trailing_sep_allowed && kets.iter().any(|k| { + match expect { + TokenExpectType::Expect => self.check(k), + TokenExpectType::NoExpect => self.token == **k, + } + }) { + break; + } + + let t = f(self)?; + v.push(t); + } + + Ok((v, recovered)) + } + + /// Parses a sequence, including the closing delimiter. The function + /// `f` must consume tokens until reaching the next separator or + /// closing bracket. + fn parse_unspanned_seq<T, F>( + &mut self, + bra: &token::Token, + ket: &token::Token, + sep: SeqSep, + f: F, + ) -> PResult<'a, Vec<T>> where + F: FnMut(&mut Parser<'a>) -> PResult<'a, T>, + { + self.expect(bra)?; + let (result, recovered) = self.parse_seq_to_before_end(ket, sep, f)?; + if !recovered { + self.eat(ket); + } + Ok(result) + } + + /// Advance the parser by one token + pub fn bump(&mut self) { + if self.prev_token_kind == PrevTokenKind::Eof { + // Bumping after EOF is a bad sign, usually an infinite loop. + self.bug("attempted to bump the parser past EOF (may be stuck in a loop)"); + } + + self.prev_span = self.meta_var_span.take().unwrap_or(self.span); + + // Record last token kind for possible error recovery. + self.prev_token_kind = match self.token { + token::DocComment(..) => PrevTokenKind::DocComment, + token::Comma => PrevTokenKind::Comma, + token::BinOp(token::Plus) => PrevTokenKind::Plus, + token::Interpolated(..) => PrevTokenKind::Interpolated, + token::Eof => PrevTokenKind::Eof, + token::Ident(..) => PrevTokenKind::Ident, + _ => PrevTokenKind::Other, + }; + + let next = self.next_tok(); + self.span = next.sp; + self.token = next.tok; + self.expected_tokens.clear(); + // check after each token + self.process_potential_macro_variable(); + } + + /// Advance the parser using provided token as a next one. Use this when + /// consuming a part of a token. For example a single `<` from `<<`. + fn bump_with(&mut self, next: token::Token, span: Span) { + self.prev_span = self.span.with_hi(span.lo()); + // It would be incorrect to record the kind of the current token, but + // fortunately for tokens currently using `bump_with`, the + // prev_token_kind will be of no use anyway. + self.prev_token_kind = PrevTokenKind::Other; + self.span = span; + self.token = next; + self.expected_tokens.clear(); + } + + pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where + F: FnOnce(&token::Token) -> R, + { + if dist == 0 { + return f(&self.token) + } + + f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) { + Some(tree) => match tree { + TokenTree::Token(_, tok) => tok, + TokenTree::Delimited(_, delim, _) => token::OpenDelim(delim), + }, + None => token::CloseDelim(self.token_cursor.frame.delim), + }) + } + + fn look_ahead_span(&self, dist: usize) -> Span { + if dist == 0 { + return self.span + } + + match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) { + Some(TokenTree::Token(span, _)) => span, + Some(TokenTree::Delimited(span, ..)) => span.entire(), + None => self.look_ahead_span(dist - 1), + } + } + pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> { + self.sess.span_diagnostic.struct_span_fatal(self.span, m) + } + pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> { + self.sess.span_diagnostic.struct_span_fatal(sp, m) + } + fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> { + err.span_err(sp, self.diagnostic()) + } + fn bug(&self, m: &str) -> ! { + self.sess.span_diagnostic.span_bug(self.span, m) + } + fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) { + self.sess.span_diagnostic.span_err(sp, m) + } + fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> { + self.sess.span_diagnostic.struct_span_err(sp, m) + } + crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! { + self.sess.span_diagnostic.span_bug(sp, m) + } + + fn cancel(&self, err: &mut DiagnosticBuilder<'_>) { + self.sess.span_diagnostic.cancel(err) + } + + crate fn diagnostic(&self) -> &'a errors::Handler { + &self.sess.span_diagnostic + } + + /// Is the current token one of the keywords that signals a bare function type? + fn token_is_bare_fn_keyword(&mut self) -> bool { + self.check_keyword(keywords::Fn) || + self.check_keyword(keywords::Unsafe) || + self.check_keyword(keywords::Extern) + } + + /// Parses a `TyKind::BareFn` type. + fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> { + /* + + [unsafe] [extern "ABI"] fn (S) -> T + ^~~~^ ^~~~^ ^~^ ^ + | | | | + | | | Return type + | | Argument types + | | + | ABI + Function Style + */ + + let unsafety = self.parse_unsafety(); + let abi = if self.eat_keyword(keywords::Extern) { + self.parse_opt_abi()?.unwrap_or(Abi::C) + } else { + Abi::Rust + }; + + self.expect_keyword(keywords::Fn)?; + let (inputs, variadic) = self.parse_fn_args(false, true)?; + let ret_ty = self.parse_ret_ty(false)?; + let decl = P(FnDecl { + inputs, + output: ret_ty, + variadic, + }); + Ok(TyKind::BareFn(P(BareFnTy { + abi, + unsafety, + generic_params, + decl, + }))) + } + + /// Parses asyncness: `async` or nothing. + fn parse_asyncness(&mut self) -> IsAsync { + if self.eat_keyword(keywords::Async) { + IsAsync::Async { + closure_id: ast::DUMMY_NODE_ID, + return_impl_trait_id: ast::DUMMY_NODE_ID, + } + } else { + IsAsync::NotAsync + } + } + + /// Parses unsafety: `unsafe` or nothing. + fn parse_unsafety(&mut self) -> Unsafety { + if self.eat_keyword(keywords::Unsafe) { + Unsafety::Unsafe + } else { + Unsafety::Normal + } + } + + /// Parses the items in a trait declaration. + pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> { + maybe_whole!(self, NtTraitItem, |x| x); + let attrs = self.parse_outer_attributes()?; + let (mut item, tokens) = self.collect_tokens(|this| { + this.parse_trait_item_(at_end, attrs) + })?; + // See `parse_item` for why this clause is here. + if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) { + item.tokens = Some(tokens); + } + Ok(item) + } + + fn parse_trait_item_(&mut self, + at_end: &mut bool, + mut attrs: Vec<Attribute>) -> PResult<'a, TraitItem> { + let lo = self.span; + + let (name, node, generics) = if self.eat_keyword(keywords::Type) { + self.parse_trait_item_assoc_ty()? + } else if self.is_const_item() { + self.expect_keyword(keywords::Const)?; + let ident = self.parse_ident()?; + self.expect(&token::Colon)?; + let ty = self.parse_ty()?; + let default = if self.eat(&token::Eq) { + let expr = self.parse_expr()?; + self.expect(&token::Semi)?; + Some(expr) + } else { + self.expect(&token::Semi)?; + None + }; + (ident, TraitItemKind::Const(ty, default), ast::Generics::default()) + } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? { + // trait item macro. + (keywords::Invalid.ident(), ast::TraitItemKind::Macro(mac), ast::Generics::default()) + } else { + let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?; + + let ident = self.parse_ident()?; + let mut generics = self.parse_generics()?; + + let d = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| { + // This is somewhat dubious; We don't want to allow + // argument names to be left off if there is a + // definition... + + // We don't allow argument names to be left off in edition 2018. + p.parse_arg_general(p.span.rust_2018(), true) + })?; + generics.where_clause = self.parse_where_clause()?; + + let sig = ast::MethodSig { + header: FnHeader { + unsafety, + constness, + abi, + asyncness, + }, + decl: d, + }; + + let body = match self.token { + token::Semi => { + self.bump(); + *at_end = true; + debug!("parse_trait_methods(): parsing required method"); + None + } + token::OpenDelim(token::Brace) => { + debug!("parse_trait_methods(): parsing provided method"); + *at_end = true; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(inner_attrs.iter().cloned()); + Some(body) + } + token::Interpolated(ref nt) => { + match **nt { + token::NtBlock(..) => { + *at_end = true; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(inner_attrs.iter().cloned()); + Some(body) + } + _ => { + let token_str = self.this_token_descr(); + let mut err = self.fatal(&format!("expected `;` or `{{`, found {}", + token_str)); + err.span_label(self.span, "expected `;` or `{`"); + return Err(err); + } + } + } + _ => { + let token_str = self.this_token_descr(); + let mut err = self.fatal(&format!("expected `;` or `{{`, found {}", + token_str)); + err.span_label(self.span, "expected `;` or `{`"); + return Err(err); + } + }; + (ident, ast::TraitItemKind::Method(sig, body), generics) + }; + + Ok(TraitItem { + id: ast::DUMMY_NODE_ID, + ident: name, + attrs, + generics, + node, + span: lo.to(self.prev_span), + tokens: None, + }) + } + + /// Parses an optional return type `[ -> TY ]` in a function declaration. + fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> { + if self.eat(&token::RArrow) { + Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true)?)) + } else { + Ok(FunctionRetTy::Default(self.span.shrink_to_lo())) + } + } + + /// Parses a type. + pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> { + self.parse_ty_common(true, true) + } + + /// Parses a type in restricted contexts where `+` is not permitted. + /// + /// Example 1: `&'a TYPE` + /// `+` is prohibited to maintain operator priority (P(+) < P(&)). + /// Example 2: `value1 as TYPE + value2` + /// `+` is prohibited to avoid interactions with expression grammar. + fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> { + self.parse_ty_common(false, true) + } + + fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool) + -> PResult<'a, P<Ty>> { + maybe_whole!(self, NtTy, |x| x); + + let lo = self.span; + let mut impl_dyn_multi = false; + let node = if self.eat(&token::OpenDelim(token::Paren)) { + // `(TYPE)` is a parenthesized type. + // `(TYPE,)` is a tuple with a single field of type TYPE. + let mut ts = vec![]; + let mut last_comma = false; + while self.token != token::CloseDelim(token::Paren) { + ts.push(self.parse_ty()?); + if self.eat(&token::Comma) { + last_comma = true; + } else { + last_comma = false; + break; + } + } + let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus; + self.expect(&token::CloseDelim(token::Paren))?; + + if ts.len() == 1 && !last_comma { + let ty = ts.into_iter().nth(0).unwrap().into_inner(); + let maybe_bounds = allow_plus && self.token.is_like_plus(); + match ty.node { + // `(TY_BOUND_NOPAREN) + BOUND + ...`. + TyKind::Path(None, ref path) if maybe_bounds => { + self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)? + } + TyKind::TraitObject(ref bounds, TraitObjectSyntax::None) + if maybe_bounds && bounds.len() == 1 && !trailing_plus => { + let path = match bounds[0] { + GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(), + GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"), + }; + self.parse_remaining_bounds(Vec::new(), path, lo, true)? + } + // `(TYPE)` + _ => TyKind::Paren(P(ty)) + } + } else { + TyKind::Tup(ts) + } + } else if self.eat(&token::Not) { + // Never type `!` + TyKind::Never + } else if self.eat(&token::BinOp(token::Star)) { + // Raw pointer + TyKind::Ptr(self.parse_ptr()?) + } else if self.eat(&token::OpenDelim(token::Bracket)) { + // Array or slice + let t = self.parse_ty()?; + // Parse optional `; EXPR` in `[TYPE; EXPR]` + let t = match self.maybe_parse_fixed_length_of_vec()? { + None => TyKind::Slice(t), + Some(length) => TyKind::Array(t, AnonConst { + id: ast::DUMMY_NODE_ID, + value: length, + }), + }; + self.expect(&token::CloseDelim(token::Bracket))?; + t + } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) { + // Reference + self.expect_and()?; + self.parse_borrowed_pointee()? + } else if self.eat_keyword_noexpect(keywords::Typeof) { + // `typeof(EXPR)` + // In order to not be ambiguous, the type must be surrounded by parens. + self.expect(&token::OpenDelim(token::Paren))?; + let e = AnonConst { + id: ast::DUMMY_NODE_ID, + value: self.parse_expr()?, + }; + self.expect(&token::CloseDelim(token::Paren))?; + TyKind::Typeof(e) + } else if self.eat_keyword(keywords::Underscore) { + // A type to be inferred `_` + TyKind::Infer + } else if self.token_is_bare_fn_keyword() { + // Function pointer type + self.parse_ty_bare_fn(Vec::new())? + } else if self.check_keyword(keywords::For) { + // Function pointer type or bound list (trait object type) starting with a poly-trait. + // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T` + // `for<'lt> Trait1<'lt> + Trait2 + 'a` + let lo = self.span; + let lifetime_defs = self.parse_late_bound_lifetime_defs()?; + if self.token_is_bare_fn_keyword() { + self.parse_ty_bare_fn(lifetime_defs)? + } else { + let path = self.parse_path(PathStyle::Type)?; + let parse_plus = allow_plus && self.check_plus(); + self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)? + } + } else if self.eat_keyword(keywords::Impl) { + // Always parse bounds greedily for better error recovery. + let bounds = self.parse_generic_bounds(None)?; + impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus; + TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds) + } else if self.check_keyword(keywords::Dyn) && + (self.span.rust_2018() || + self.look_ahead(1, |t| t.can_begin_bound() && + !can_continue_type_after_non_fn_ident(t))) { + self.bump(); // `dyn` + // Always parse bounds greedily for better error recovery. + let bounds = self.parse_generic_bounds(None)?; + impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus; + TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn) + } else if self.check(&token::Question) || + self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) { + // Bound list (trait object type) + TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus, None)?, + TraitObjectSyntax::None) + } else if self.eat_lt() { + // Qualified path + let (qself, path) = self.parse_qpath(PathStyle::Type)?; + TyKind::Path(Some(qself), path) + } else if self.token.is_path_start() { + // Simple path + let path = self.parse_path(PathStyle::Type)?; + if self.eat(&token::Not) { + // Macro invocation in type position + let (delim, tts) = self.expect_delimited_token_tree()?; + let node = Mac_ { path, tts, delim }; + TyKind::Mac(respan(lo.to(self.prev_span), node)) + } else { + // Just a type path or bound list (trait object type) starting with a trait. + // `Type` + // `Trait1 + Trait2 + 'a` + if allow_plus && self.check_plus() { + self.parse_remaining_bounds(Vec::new(), path, lo, true)? + } else { + TyKind::Path(None, path) + } + } + } else { + let msg = format!("expected type, found {}", self.this_token_descr()); + return Err(self.fatal(&msg)); + }; + + let span = lo.to(self.prev_span); + let ty = Ty { node, span, id: ast::DUMMY_NODE_ID }; + + // Try to recover from use of `+` with incorrect priority. + self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty); + self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?; + let ty = self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)?; + + Ok(P(ty)) + } + + fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path, + lo: Span, parse_plus: bool) -> PResult<'a, TyKind> { + let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span)); + let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)]; + if parse_plus { + self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded + bounds.append(&mut self.parse_generic_bounds(None)?); + } + Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None)) + } + + fn maybe_report_ambiguous_plus(&mut self, allow_plus: bool, impl_dyn_multi: bool, ty: &Ty) { + if !allow_plus && impl_dyn_multi { + let sum_with_parens = format!("({})", pprust::ty_to_string(&ty)); + self.struct_span_err(ty.span, "ambiguous `+` in a type") + .span_suggestion( + ty.span, + "use parentheses to disambiguate", + sum_with_parens, + Applicability::MachineApplicable + ).emit(); + } + } + + fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> { + // Do not add `+` to expected tokens. + if !allow_plus || !self.token.is_like_plus() { + return Ok(()) + } + + self.bump(); // `+` + let bounds = self.parse_generic_bounds(None)?; + let sum_span = ty.span.to(self.prev_span); + + let mut err = struct_span_err!(self.sess.span_diagnostic, sum_span, E0178, + "expected a path on the left-hand side of `+`, not `{}`", pprust::ty_to_string(ty)); + + match ty.node { + TyKind::Rptr(ref lifetime, ref mut_ty) => { + let sum_with_parens = pprust::to_string(|s| { + use crate::print::pprust::PrintState; + + s.s.word("&")?; + s.print_opt_lifetime(lifetime)?; + s.print_mutability(mut_ty.mutbl)?; + s.popen()?; + s.print_type(&mut_ty.ty)?; + s.print_type_bounds(" +", &bounds)?; + s.pclose() + }); + err.span_suggestion( + sum_span, + "try adding parentheses", + sum_with_parens, + Applicability::MachineApplicable + ); + } + TyKind::Ptr(..) | TyKind::BareFn(..) => { + err.span_label(sum_span, "perhaps you forgot parentheses?"); + } + _ => { + err.span_label(sum_span, "expected a path"); + }, + } + err.emit(); + Ok(()) + } + + // Try to recover from associated item paths like `[T]::AssocItem`/`(T, U)::AssocItem`. + fn maybe_recover_from_bad_qpath<T: RecoverQPath>(&mut self, base: T, allow_recovery: bool) + -> PResult<'a, T> { + // Do not add `::` to expected tokens. + if !allow_recovery || self.token != token::ModSep { + return Ok(base); + } + let ty = match base.to_ty() { + Some(ty) => ty, + None => return Ok(base), + }; + + self.bump(); // `::` + let mut segments = Vec::new(); + self.parse_path_segments(&mut segments, T::PATH_STYLE, true)?; + + let span = ty.span.to(self.prev_span); + let path_span = span.to(span); // use an empty path since `position` == 0 + let recovered = base.to_recovered( + Some(QSelf { ty, path_span, position: 0 }), + ast::Path { segments, span }, + ); + + self.diagnostic() + .struct_span_err(span, "missing angle brackets in associated item path") + .span_suggestion( // this is a best-effort recovery + span, "try", recovered.to_string(), Applicability::MaybeIncorrect + ).emit(); + + Ok(recovered) + } + + fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> { + let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None }; + let mutbl = self.parse_mutability(); + let ty = self.parse_ty_no_plus()?; + return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl })); + } + + fn parse_ptr(&mut self) -> PResult<'a, MutTy> { + let mutbl = if self.eat_keyword(keywords::Mut) { + Mutability::Mutable + } else if self.eat_keyword(keywords::Const) { + Mutability::Immutable + } else { + let span = self.prev_span; + let msg = "expected mut or const in raw pointer type"; + self.struct_span_err(span, msg) + .span_label(span, msg) + .help("use `*mut T` or `*const T` as appropriate") + .emit(); + Mutability::Immutable + }; + let t = self.parse_ty_no_plus()?; + Ok(MutTy { ty: t, mutbl: mutbl }) + } + + fn is_named_argument(&mut self) -> bool { + let offset = match self.token { + token::Interpolated(ref nt) => match **nt { + token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon), + _ => 0, + } + token::BinOp(token::And) | token::AndAnd => 1, + _ if self.token.is_keyword(keywords::Mut) => 1, + _ => 0, + }; + + self.look_ahead(offset, |t| t.is_ident()) && + self.look_ahead(offset + 1, |t| t == &token::Colon) + } + + /// Skips unexpected attributes and doc comments in this position and emits an appropriate + /// error. + fn eat_incorrect_doc_comment(&mut self, applied_to: &str) { + if let token::DocComment(_) = self.token { + let mut err = self.diagnostic().struct_span_err( + self.span, + &format!("documentation comments cannot be applied to {}", applied_to), + ); + err.span_label(self.span, "doc comments are not allowed here"); + err.emit(); + self.bump(); + } else if self.token == token::Pound && self.look_ahead(1, |t| { + *t == token::OpenDelim(token::Bracket) + }) { + let lo = self.span; + // Skip every token until next possible arg. + while self.token != token::CloseDelim(token::Bracket) { + self.bump(); + } + let sp = lo.to(self.span); + self.bump(); + let mut err = self.diagnostic().struct_span_err( + sp, + &format!("attributes cannot be applied to {}", applied_to), + ); + err.span_label(sp, "attributes are not allowed here"); + err.emit(); + } + } + + /// This version of parse arg doesn't necessarily require identifier names. + fn parse_arg_general(&mut self, require_name: bool, is_trait_item: bool) -> PResult<'a, Arg> { + maybe_whole!(self, NtArg, |x| x); + + if let Ok(Some(_)) = self.parse_self_arg() { + let mut err = self.struct_span_err(self.prev_span, + "unexpected `self` argument in function"); + err.span_label(self.prev_span, + "`self` is only valid as the first argument of an associated function"); + return Err(err); + } + + let (pat, ty) = if require_name || self.is_named_argument() { + debug!("parse_arg_general parse_pat (require_name:{})", + require_name); + self.eat_incorrect_doc_comment("method arguments"); + let pat = self.parse_pat(Some("argument name"))?; + + if let Err(mut err) = self.expect(&token::Colon) { + // If we find a pattern followed by an identifier, it could be an (incorrect) + // C-style parameter declaration. + if self.check_ident() && self.look_ahead(1, |t| { + *t == token::Comma || *t == token::CloseDelim(token::Paren) + }) { + let ident = self.parse_ident().unwrap(); + let span = pat.span.with_hi(ident.span.hi()); + + err.span_suggestion( + span, + "declare the type after the parameter binding", + String::from("<identifier>: <type>"), + Applicability::HasPlaceholders, + ); + } else if require_name && is_trait_item { + if let PatKind::Ident(_, ident, _) = pat.node { + err.span_suggestion( + pat.span, + "explicitly ignore parameter", + format!("_: {}", ident), + Applicability::MachineApplicable, + ); + } + + err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)"); + } + + return Err(err); + } + + self.eat_incorrect_doc_comment("a method argument's type"); + (pat, self.parse_ty()?) + } else { + debug!("parse_arg_general ident_to_pat"); + let parser_snapshot_before_ty = self.clone(); + self.eat_incorrect_doc_comment("a method argument's type"); + let mut ty = self.parse_ty(); + if ty.is_ok() && self.token != token::Comma && + self.token != token::CloseDelim(token::Paren) { + // This wasn't actually a type, but a pattern looking like a type, + // so we are going to rollback and re-parse for recovery. + ty = self.unexpected(); + } + match ty { + Ok(ty) => { + let ident = Ident::new(keywords::Invalid.name(), self.prev_span); + let pat = P(Pat { + id: ast::DUMMY_NODE_ID, + node: PatKind::Ident( + BindingMode::ByValue(Mutability::Immutable), ident, None), + span: ty.span, + }); + (pat, ty) + } + Err(mut err) => { + // Recover from attempting to parse the argument as a type without pattern. + err.cancel(); + mem::replace(self, parser_snapshot_before_ty); + let pat = self.parse_pat(Some("argument name"))?; + self.expect(&token::Colon)?; + let ty = self.parse_ty()?; + + let mut err = self.diagnostic().struct_span_err_with_code( + pat.span, + "patterns aren't allowed in methods without bodies", + DiagnosticId::Error("E0642".into()), + ); + err.span_suggestion_short( + pat.span, + "give this argument a name or use an underscore to ignore it", + "_".to_owned(), + Applicability::MachineApplicable, + ); + err.emit(); + + // Pretend the pattern is `_`, to avoid duplicate errors from AST validation. + let pat = P(Pat { + node: PatKind::Wild, + span: pat.span, + id: ast::DUMMY_NODE_ID + }); + (pat, ty) + } + } + }; + + Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID }) + } + + /// Parses a single function argument. + crate fn parse_arg(&mut self) -> PResult<'a, Arg> { + self.parse_arg_general(true, false) + } + + /// Parses an argument in a lambda header (e.g., `|arg, arg|`). + fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> { + let pat = self.parse_pat(Some("argument name"))?; + let t = if self.eat(&token::Colon) { + self.parse_ty()? + } else { + P(Ty { + id: ast::DUMMY_NODE_ID, + node: TyKind::Infer, + span: self.prev_span, + }) + }; + Ok(Arg { + ty: t, + pat, + id: ast::DUMMY_NODE_ID + }) + } + + fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> { + if self.eat(&token::Semi) { + Ok(Some(self.parse_expr()?)) + } else { + Ok(None) + } + } + + /// Matches `token_lit = LIT_INTEGER | ...`. + fn parse_lit_token(&mut self) -> PResult<'a, LitKind> { + let out = match self.token { + token::Interpolated(ref nt) => match **nt { + token::NtExpr(ref v) | token::NtLiteral(ref v) => match v.node { + ExprKind::Lit(ref lit) => { lit.node.clone() } + _ => { return self.unexpected_last(&self.token); } + }, + _ => { return self.unexpected_last(&self.token); } + }, + token::Literal(lit, suf) => { + let diag = Some((self.span, &self.sess.span_diagnostic)); + let (suffix_illegal, result) = parse::lit_token(lit, suf, diag); + + if suffix_illegal { + let sp = self.span; + self.expect_no_suffix(sp, lit.literal_name(), suf) + } + + result.unwrap() + } + token::Dot if self.look_ahead(1, |t| match t { + token::Literal(parse::token::Lit::Integer(_) , _) => true, + _ => false, + }) => { // recover from `let x = .4;` + let lo = self.span; + self.bump(); + if let token::Literal( + parse::token::Lit::Integer(val), + suffix, + ) = self.token { + let suffix = suffix.and_then(|s| { + let s = s.as_str().get(); + if ["f32", "f64"].contains(&s) { + Some(s) + } else { + None + } + }).unwrap_or(""); + self.bump(); + let sp = lo.to(self.prev_span); + let mut err = self.diagnostic() + .struct_span_err(sp, "float literals must have an integer part"); + err.span_suggestion( + sp, + "must have an integer part", + format!("0.{}{}", val, suffix), + Applicability::MachineApplicable, + ); + err.emit(); + return Ok(match suffix { + "f32" => ast::LitKind::Float(val, ast::FloatTy::F32), + "f64" => ast::LitKind::Float(val, ast::FloatTy::F64), + _ => ast::LitKind::FloatUnsuffixed(val), + }); + } else { + unreachable!(); + }; + } + _ => { return self.unexpected_last(&self.token); } + }; + + self.bump(); + Ok(out) + } + + /// Matches `lit = true | false | token_lit`. + crate fn parse_lit(&mut self) -> PResult<'a, Lit> { + let lo = self.span; + let lit = if self.eat_keyword(keywords::True) { + LitKind::Bool(true) + } else if self.eat_keyword(keywords::False) { + LitKind::Bool(false) + } else { + let lit = self.parse_lit_token()?; + lit + }; + Ok(source_map::Spanned { node: lit, span: lo.to(self.prev_span) }) + } + + /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`). + crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> { + maybe_whole_expr!(self); + + let minus_lo = self.span; + let minus_present = self.eat(&token::BinOp(token::Minus)); + let lo = self.span; + let literal = self.parse_lit()?; + let hi = self.prev_span; + let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new()); + + if minus_present { + let minus_hi = self.prev_span; + let unary = self.mk_unary(UnOp::Neg, expr); + Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new())) + } else { + Ok(expr) + } + } + + fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> { + match self.token { + token::Ident(ident, _) if self.token.is_path_segment_keyword() => { + let span = self.span; + self.bump(); + Ok(Ident::new(ident.name, span)) + } + _ => self.parse_ident(), + } + } + + fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> { + match self.token { + token::Ident(ident, false) if ident.name == keywords::Underscore.name() => { + let span = self.span; + self.bump(); + Ok(Ident::new(ident.name, span)) + } + _ => self.parse_ident(), + } + } + + /// Parses a qualified path. + /// Assumes that the leading `<` has been parsed already. + /// + /// `qualified_path = <type [as trait_ref]>::path` + /// + /// # Examples + /// `<T>::default` + /// `<T as U>::a` + /// `<T as U>::F::a<S>` (without disambiguator) + /// `<T as U>::F::a::<S>` (with disambiguator) + fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::Path)> { + let lo = self.prev_span; + let ty = self.parse_ty()?; + + // `path` will contain the prefix of the path up to the `>`, + // if any (e.g., `U` in the `<T as U>::*` examples + // above). `path_span` has the span of that path, or an empty + // span in the case of something like `<T>::Bar`. + let (mut path, path_span); + if self.eat_keyword(keywords::As) { + let path_lo = self.span; + path = self.parse_path(PathStyle::Type)?; + path_span = path_lo.to(self.prev_span); + } else { + path = ast::Path { segments: Vec::new(), span: syntax_pos::DUMMY_SP }; + path_span = self.span.to(self.span); + } + + // See doc comment for `unmatched_angle_bracket_count`. + self.expect(&token::Gt)?; + if self.unmatched_angle_bracket_count > 0 { + self.unmatched_angle_bracket_count -= 1; + debug!("parse_qpath: (decrement) count={:?}", self.unmatched_angle_bracket_count); + } + + self.expect(&token::ModSep)?; + + let qself = QSelf { ty, path_span, position: path.segments.len() }; + self.parse_path_segments(&mut path.segments, style, true)?; + + Ok((qself, ast::Path { segments: path.segments, span: lo.to(self.prev_span) })) + } + + /// Parses simple paths. + /// + /// `path = [::] segment+` + /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]` + /// + /// # Examples + /// `a::b::C<D>` (without disambiguator) + /// `a::b::C::<D>` (with disambiguator) + /// `Fn(Args)` (without disambiguator) + /// `Fn::(Args)` (with disambiguator) + pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, ast::Path> { + self.parse_path_common(style, true) + } + + crate fn parse_path_common(&mut self, style: PathStyle, enable_warning: bool) + -> PResult<'a, ast::Path> { + maybe_whole!(self, NtPath, |path| { + if style == PathStyle::Mod && + path.segments.iter().any(|segment| segment.args.is_some()) { + self.diagnostic().span_err(path.span, "unexpected generic arguments in path"); + } + path + }); + + let lo = self.meta_var_span.unwrap_or(self.span); + let mut segments = Vec::new(); + let mod_sep_ctxt = self.span.ctxt(); + if self.eat(&token::ModSep) { + segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))); + } + self.parse_path_segments(&mut segments, style, enable_warning)?; + + Ok(ast::Path { segments, span: lo.to(self.prev_span) }) + } + + /// Like `parse_path`, but also supports parsing `Word` meta items into paths for + /// backwards-compatibility. This is used when parsing derive macro paths in `#[derive]` + /// attributes. + pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> { + let meta_ident = match self.token { + token::Interpolated(ref nt) => match **nt { + token::NtMeta(ref meta) => match meta.node { + ast::MetaItemKind::Word => Some(meta.ident.clone()), + _ => None, + }, + _ => None, + }, + _ => None, + }; + if let Some(path) = meta_ident { + self.bump(); + return Ok(path); + } + self.parse_path(style) + } + + fn parse_path_segments(&mut self, + segments: &mut Vec<PathSegment>, + style: PathStyle, + enable_warning: bool) + -> PResult<'a, ()> { + loop { + let segment = self.parse_path_segment(style, enable_warning)?; + if style == PathStyle::Expr { + // In order to check for trailing angle brackets, we must have finished + // recursing (`parse_path_segment` can indirectly call this function), + // that is, the next token must be the highlighted part of the below example: + // + // `Foo::<Bar as Baz<T>>::Qux` + // ^ here + // + // As opposed to the below highlight (if we had only finished the first + // recursion): + // + // `Foo::<Bar as Baz<T>>::Qux` + // ^ here + // + // `PathStyle::Expr` is only provided at the root invocation and never in + // `parse_path_segment` to recurse and therefore can be checked to maintain + // this invariant. + self.check_trailing_angle_brackets(&segment, token::ModSep); + } + segments.push(segment); + + if self.is_import_coupler() || !self.eat(&token::ModSep) { + return Ok(()); + } + } + } + + fn parse_path_segment(&mut self, style: PathStyle, enable_warning: bool) + -> PResult<'a, PathSegment> { + let ident = self.parse_path_segment_ident()?; + + let is_args_start = |token: &token::Token| match *token { + token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren) => true, + _ => false, + }; + let check_args_start = |this: &mut Self| { + this.expected_tokens.extend_from_slice( + &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))] + ); + is_args_start(&this.token) + }; + + Ok(if style == PathStyle::Type && check_args_start(self) || + style != PathStyle::Mod && self.check(&token::ModSep) + && self.look_ahead(1, |t| is_args_start(t)) { + // Generic arguments are found - `<`, `(`, `::<` or `::(`. + if self.eat(&token::ModSep) && style == PathStyle::Type && enable_warning { + self.diagnostic().struct_span_warn(self.prev_span, "unnecessary path disambiguator") + .span_label(self.prev_span, "try removing `::`").emit(); + } + let lo = self.span; + + // We use `style == PathStyle::Expr` to check if this is in a recursion or not. If + // it isn't, then we reset the unmatched angle bracket count as we're about to start + // parsing a new path. + if style == PathStyle::Expr { + self.unmatched_angle_bracket_count = 0; + self.max_angle_bracket_count = 0; + } + + let args = if self.eat_lt() { + // `<'a, T, A = U>` + let (args, bindings) = + self.parse_generic_args_with_leaning_angle_bracket_recovery(style, lo)?; + self.expect_gt()?; + let span = lo.to(self.prev_span); + AngleBracketedArgs { args, bindings, span }.into() + } else { + // `(T, U) -> R` + self.bump(); // `(` + let (inputs, recovered) = self.parse_seq_to_before_tokens( + &[&token::CloseDelim(token::Paren)], + SeqSep::trailing_allowed(token::Comma), + TokenExpectType::Expect, + |p| p.parse_ty())?; + if !recovered { + self.bump(); // `)` + } + let span = lo.to(self.prev_span); + let output = if self.eat(&token::RArrow) { + Some(self.parse_ty_common(false, false)?) + } else { + None + }; + ParenthesizedArgs { inputs, output, span }.into() + }; + + PathSegment { ident, args, id: ast::DUMMY_NODE_ID } + } else { + // Generic arguments are not found. + PathSegment::from_ident(ident) + }) + } + + crate fn check_lifetime(&mut self) -> bool { + self.expected_tokens.push(TokenType::Lifetime); + self.token.is_lifetime() + } + + /// Parses a single lifetime `'a` or panics. + crate fn expect_lifetime(&mut self) -> Lifetime { + if let Some(ident) = self.token.lifetime() { + let span = self.span; + self.bump(); + Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID } + } else { + self.span_bug(self.span, "not a lifetime") + } + } + + fn eat_label(&mut self) -> Option<Label> { + if let Some(ident) = self.token.lifetime() { + let span = self.span; + self.bump(); + Some(Label { ident: Ident::new(ident.name, span) }) + } else { + None + } + } + + /// Parses mutability (`mut` or nothing). + fn parse_mutability(&mut self) -> Mutability { + if self.eat_keyword(keywords::Mut) { + Mutability::Mutable + } else { + Mutability::Immutable + } + } + + fn parse_field_name(&mut self) -> PResult<'a, Ident> { + if let token::Literal(token::Integer(name), None) = self.token { + self.bump(); + Ok(Ident::new(name, self.prev_span)) + } else { + self.parse_ident_common(false) + } + } + + /// Parse ident (COLON expr)? + fn parse_field(&mut self) -> PResult<'a, Field> { + let attrs = self.parse_outer_attributes()?; + let lo = self.span; + + // Check if a colon exists one ahead. This means we're parsing a fieldname. + let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| { + t == &token::Colon || t == &token::Eq + }) { + let fieldname = self.parse_field_name()?; + + // Check for an equals token. This means the source incorrectly attempts to + // initialize a field with an eq rather than a colon. + if self.token == token::Eq { + self.diagnostic() + .struct_span_err(self.span, "expected `:`, found `=`") + .span_suggestion( + fieldname.span.shrink_to_hi().to(self.span), + "replace equals symbol with a colon", + ":".to_string(), + Applicability::MachineApplicable, + ) + .emit(); + } + self.bump(); // `:` + (fieldname, self.parse_expr()?, false) + } else { + let fieldname = self.parse_ident_common(false)?; + + // Mimic `x: x` for the `x` field shorthand. + let path = ast::Path::from_ident(fieldname); + let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new()); + (fieldname, expr, true) + }; + Ok(ast::Field { + ident: fieldname, + span: lo.to(expr.span), + expr, + is_shorthand, + attrs: attrs.into(), + }) + } + + fn mk_expr(&mut self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> { + P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID }) + } + + fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind { + ExprKind::Unary(unop, expr) + } + + fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind { + ExprKind::Binary(binop, lhs, rhs) + } + + fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind { + ExprKind::Call(f, args) + } + + fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind { + ExprKind::Index(expr, idx) + } + + fn mk_range(&mut self, + start: Option<P<Expr>>, + end: Option<P<Expr>>, + limits: RangeLimits) + -> PResult<'a, ast::ExprKind> { + if end.is_none() && limits == RangeLimits::Closed { + Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd)) + } else { + Ok(ExprKind::Range(start, end, limits)) + } + } + + fn mk_assign_op(&mut self, binop: ast::BinOp, + lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind { + ExprKind::AssignOp(binop, lhs, rhs) + } + + pub fn mk_mac_expr(&mut self, span: Span, m: Mac_, attrs: ThinVec<Attribute>) -> P<Expr> { + P(Expr { + id: ast::DUMMY_NODE_ID, + node: ExprKind::Mac(source_map::Spanned {node: m, span: span}), + span, + attrs, + }) + } + + fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, TokenStream)> { + let delim = match self.token { + token::OpenDelim(delim) => delim, + _ => { + let msg = "expected open delimiter"; + let mut err = self.fatal(msg); + err.span_label(self.span, msg); + return Err(err) + } + }; + let tts = match self.parse_token_tree() { + TokenTree::Delimited(_, _, tts) => tts, + _ => unreachable!(), + }; + let delim = match delim { + token::Paren => MacDelimiter::Parenthesis, + token::Bracket => MacDelimiter::Bracket, + token::Brace => MacDelimiter::Brace, + token::NoDelim => self.bug("unexpected no delimiter"), + }; + Ok((delim, tts.into())) + } + + /// At the bottom (top?) of the precedence hierarchy, + /// Parses things like parenthesized exprs, macros, `return`, etc. + /// + /// N.B., this does not parse outer attributes, and is private because it only works + /// correctly if called from `parse_dot_or_call_expr()`. + fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> { + maybe_whole_expr!(self); + + // Outer attributes are already parsed and will be + // added to the return value after the fact. + // + // Therefore, prevent sub-parser from parsing + // attributes by giving them a empty "already parsed" list. + let mut attrs = ThinVec::new(); + + let lo = self.span; + let mut hi = self.span; + + let ex: ExprKind; + + // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr(). + match self.token { + token::OpenDelim(token::Paren) => { + self.bump(); + + attrs.extend(self.parse_inner_attributes()?); + + // (e) is parenthesized e + // (e,) is a tuple with only one field, e + let mut es = vec![]; + let mut trailing_comma = false; + let mut recovered = false; + while self.token != token::CloseDelim(token::Paren) { + es.push(self.parse_expr()?); + recovered = self.expect_one_of( + &[], + &[token::Comma, token::CloseDelim(token::Paren)], + )?; + if self.eat(&token::Comma) { + trailing_comma = true; + } else { + trailing_comma = false; + break; + } + } + if !recovered { + self.bump(); + } + + hi = self.prev_span; + ex = if es.len() == 1 && !trailing_comma { + ExprKind::Paren(es.into_iter().nth(0).unwrap()) + } else { + ExprKind::Tup(es) + }; + } + token::OpenDelim(token::Brace) => { + return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs); + } + token::BinOp(token::Or) | token::OrOr => { + return self.parse_lambda_expr(attrs); + } + token::OpenDelim(token::Bracket) => { + self.bump(); + + attrs.extend(self.parse_inner_attributes()?); + + if self.eat(&token::CloseDelim(token::Bracket)) { + // Empty vector. + ex = ExprKind::Array(Vec::new()); + } else { + // Nonempty vector. + let first_expr = self.parse_expr()?; + if self.eat(&token::Semi) { + // Repeating array syntax: [ 0; 512 ] + let count = AnonConst { + id: ast::DUMMY_NODE_ID, + value: self.parse_expr()?, + }; + self.expect(&token::CloseDelim(token::Bracket))?; + ex = ExprKind::Repeat(first_expr, count); + } else if self.eat(&token::Comma) { + // Vector with two or more elements. + let remaining_exprs = self.parse_seq_to_end( + &token::CloseDelim(token::Bracket), + SeqSep::trailing_allowed(token::Comma), + |p| Ok(p.parse_expr()?) + )?; + let mut exprs = vec![first_expr]; + exprs.extend(remaining_exprs); + ex = ExprKind::Array(exprs); + } else { + // Vector with one element. + self.expect(&token::CloseDelim(token::Bracket))?; + ex = ExprKind::Array(vec![first_expr]); + } + } + hi = self.prev_span; + } + _ => { + if self.eat_lt() { + let (qself, path) = self.parse_qpath(PathStyle::Expr)?; + hi = path.span; + return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs)); + } + if self.span.rust_2018() && self.check_keyword(keywords::Async) + { + if self.is_async_block() { // check for `async {` and `async move {` + return self.parse_async_block(attrs); + } else { + return self.parse_lambda_expr(attrs); + } + } + if self.check_keyword(keywords::Move) || self.check_keyword(keywords::Static) { + return self.parse_lambda_expr(attrs); + } + if self.eat_keyword(keywords::If) { + return self.parse_if_expr(attrs); + } + if self.eat_keyword(keywords::For) { + let lo = self.prev_span; + return self.parse_for_expr(None, lo, attrs); + } + if self.eat_keyword(keywords::While) { + let lo = self.prev_span; + return self.parse_while_expr(None, lo, attrs); + } + if let Some(label) = self.eat_label() { + let lo = label.ident.span; + self.expect(&token::Colon)?; + if self.eat_keyword(keywords::While) { + return self.parse_while_expr(Some(label), lo, attrs) + } + if self.eat_keyword(keywords::For) { + return self.parse_for_expr(Some(label), lo, attrs) + } + if self.eat_keyword(keywords::Loop) { + return self.parse_loop_expr(Some(label), lo, attrs) + } + if self.token == token::OpenDelim(token::Brace) { + return self.parse_block_expr(Some(label), + lo, + BlockCheckMode::Default, + attrs); + } + let msg = "expected `while`, `for`, `loop` or `{` after a label"; + let mut err = self.fatal(msg); + err.span_label(self.span, msg); + return Err(err); + } + if self.eat_keyword(keywords::Loop) { + let lo = self.prev_span; + return self.parse_loop_expr(None, lo, attrs); + } + if self.eat_keyword(keywords::Continue) { + let label = self.eat_label(); + let ex = ExprKind::Continue(label); + let hi = self.prev_span; + return Ok(self.mk_expr(lo.to(hi), ex, attrs)); + } + if self.eat_keyword(keywords::Match) { + let match_sp = self.prev_span; + return self.parse_match_expr(attrs).map_err(|mut err| { + err.span_label(match_sp, "while parsing this match expression"); + err + }); + } + if self.eat_keyword(keywords::Unsafe) { + return self.parse_block_expr( + None, + lo, + BlockCheckMode::Unsafe(ast::UserProvided), + attrs); + } + if self.is_do_catch_block() { + let mut db = self.fatal("found removed `do catch` syntax"); + db.help("Following RFC #2388, the new non-placeholder syntax is `try`"); + return Err(db); + } + if self.is_try_block() { + let lo = self.span; + assert!(self.eat_keyword(keywords::Try)); + return self.parse_try_block(lo, attrs); + } + if self.eat_keyword(keywords::Return) { + if self.token.can_begin_expr() { + let e = self.parse_expr()?; + hi = e.span; + ex = ExprKind::Ret(Some(e)); + } else { + ex = ExprKind::Ret(None); + } + } else if self.eat_keyword(keywords::Break) { + let label = self.eat_label(); + let e = if self.token.can_begin_expr() + && !(self.token == token::OpenDelim(token::Brace) + && self.restrictions.contains( + Restrictions::NO_STRUCT_LITERAL)) { + Some(self.parse_expr()?) + } else { + None + }; + ex = ExprKind::Break(label, e); + hi = self.prev_span; + } else if self.eat_keyword(keywords::Yield) { + if self.token.can_begin_expr() { + let e = self.parse_expr()?; + hi = e.span; + ex = ExprKind::Yield(Some(e)); + } else { + ex = ExprKind::Yield(None); + } + } else if self.token.is_keyword(keywords::Let) { + // Catch this syntax error here, instead of in `parse_ident`, so + // that we can explicitly mention that let is not to be used as an expression + let mut db = self.fatal("expected expression, found statement (`let`)"); + db.span_label(self.span, "expected expression"); + db.note("variable declaration using `let` is a statement"); + return Err(db); + } else if self.token.is_path_start() { + let pth = self.parse_path(PathStyle::Expr)?; + + // `!`, as an operator, is prefix, so we know this isn't that + if self.eat(&token::Not) { + // MACRO INVOCATION expression + let (delim, tts) = self.expect_delimited_token_tree()?; + let hi = self.prev_span; + let node = Mac_ { path: pth, tts, delim }; + return Ok(self.mk_mac_expr(lo.to(hi), node, attrs)) + } + if self.check(&token::OpenDelim(token::Brace)) { + // This is a struct literal, unless we're prohibited + // from parsing struct literals here. + let prohibited = self.restrictions.contains( + Restrictions::NO_STRUCT_LITERAL + ); + if !prohibited { + return self.parse_struct_expr(lo, pth, attrs); + } + } + + hi = pth.span; + ex = ExprKind::Path(None, pth); + } else { + if !self.unclosed_delims.is_empty() && self.check(&token::Semi) { + // Don't complain about bare semicolons after unclosed braces + // recovery in order to keep the error count down. Fixing the + // delimiters will possibly also fix the bare semicolon found in + // expression context. For example, silence the following error: + // ``` + // error: expected expression, found `;` + // --> file.rs:2:13 + // | + // 2 | foo(bar(; + // | ^ expected expression + // ``` + self.bump(); + return Ok(self.mk_expr(self.span, ExprKind::Err, ThinVec::new())); + } + match self.parse_literal_maybe_minus() { + Ok(expr) => { + hi = expr.span; + ex = expr.node.clone(); + } + Err(mut err) => { + self.cancel(&mut err); + let msg = format!("expected expression, found {}", + self.this_token_descr()); + let mut err = self.fatal(&msg); + err.span_label(self.span, "expected expression"); + return Err(err); + } + } + } + } + } + + let expr = Expr { node: ex, span: lo.to(hi), id: ast::DUMMY_NODE_ID, attrs }; + let expr = self.maybe_recover_from_bad_qpath(expr, true)?; + + return Ok(P(expr)); + } + + fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Attribute>) + -> PResult<'a, P<Expr>> { + let struct_sp = lo.to(self.prev_span); + self.bump(); + let mut fields = Vec::new(); + let mut base = None; + + attrs.extend(self.parse_inner_attributes()?); + + while self.token != token::CloseDelim(token::Brace) { + if self.eat(&token::DotDot) { + let exp_span = self.prev_span; + match self.parse_expr() { + Ok(e) => { + base = Some(e); + } + Err(mut e) => { + e.emit(); + self.recover_stmt(); + } + } + if self.token == token::Comma { + let mut err = self.sess.span_diagnostic.mut_span_err( + exp_span.to(self.prev_span), + "cannot use a comma after the base struct", + ); + err.span_suggestion_short( + self.span, + "remove this comma", + String::new(), + Applicability::MachineApplicable + ); + err.note("the base struct must always be the last field"); + err.emit(); + self.recover_stmt(); + } + break; + } + + let mut recovery_field = None; + if let token::Ident(ident, _) = self.token { + if !self.token.is_reserved_ident() && self.look_ahead(1, |t| *t == token::Colon) { + // Use in case of error after field-looking code: `S { foo: () with a }` + let mut ident = ident.clone(); + ident.span = self.span; + recovery_field = Some(ast::Field { + ident, + span: self.span, + expr: self.mk_expr(self.span, ExprKind::Err, ThinVec::new()), + is_shorthand: false, + attrs: ThinVec::new(), + }); + } + } + let mut parsed_field = None; + match self.parse_field() { + Ok(f) => parsed_field = Some(f), + Err(mut e) => { + e.span_label(struct_sp, "while parsing this struct"); + e.emit(); + + // If the next token is a comma, then try to parse + // what comes next as additional fields, rather than + // bailing out until next `}`. + if self.token != token::Comma { + self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore); + if self.token != token::Comma { + break; + } + } + } + } + + match self.expect_one_of(&[token::Comma], + &[token::CloseDelim(token::Brace)]) { + Ok(_) => if let Some(f) = parsed_field.or(recovery_field) { + // only include the field if there's no parse error for the field name + fields.push(f); + } + Err(mut e) => { + if let Some(f) = recovery_field { + fields.push(f); + } + e.span_label(struct_sp, "while parsing this struct"); + e.emit(); + self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore); + self.eat(&token::Comma); + } + } + } + + let span = lo.to(self.span); + self.expect(&token::CloseDelim(token::Brace))?; + return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs)); + } + + fn parse_or_use_outer_attributes(&mut self, + already_parsed_attrs: Option<ThinVec<Attribute>>) + -> PResult<'a, ThinVec<Attribute>> { + if let Some(attrs) = already_parsed_attrs { + Ok(attrs) + } else { + self.parse_outer_attributes().map(|a| a.into()) + } + } + + /// Parses a block or unsafe block. + fn parse_block_expr(&mut self, opt_label: Option<Label>, + lo: Span, blk_mode: BlockCheckMode, + outer_attrs: ThinVec<Attribute>) + -> PResult<'a, P<Expr>> { + self.expect(&token::OpenDelim(token::Brace))?; + + let mut attrs = outer_attrs; + attrs.extend(self.parse_inner_attributes()?); + + let blk = self.parse_block_tail(lo, blk_mode)?; + return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs)); + } + + /// Parses `a.b` or `a(13)` or `a[4]` or just `a`. + fn parse_dot_or_call_expr(&mut self, + already_parsed_attrs: Option<ThinVec<Attribute>>) + -> PResult<'a, P<Expr>> { + let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?; + + let b = self.parse_bottom_expr(); + let (span, b) = self.interpolated_or_expr_span(b)?; + self.parse_dot_or_call_expr_with(b, span, attrs) + } + + fn parse_dot_or_call_expr_with(&mut self, + e0: P<Expr>, + lo: Span, + mut attrs: ThinVec<Attribute>) + -> PResult<'a, P<Expr>> { + // Stitch the list of outer attributes onto the return value. + // A little bit ugly, but the best way given the current code + // structure + self.parse_dot_or_call_expr_with_(e0, lo) + .map(|expr| + expr.map(|mut expr| { + attrs.extend::<Vec<_>>(expr.attrs.into()); + expr.attrs = attrs; + match expr.node { + ExprKind::If(..) | ExprKind::IfLet(..) => { + if !expr.attrs.is_empty() { + // Just point to the first attribute in there... + let span = expr.attrs[0].span; + + self.span_err(span, + "attributes are not yet allowed on `if` \ + expressions"); + } + } + _ => {} + } + expr + }) + ) + } + + // Assuming we have just parsed `.`, continue parsing into an expression. + fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> { + let segment = self.parse_path_segment(PathStyle::Expr, true)?; + self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren)); + + Ok(match self.token { + token::OpenDelim(token::Paren) => { + // Method call `expr.f()` + let mut args = self.parse_unspanned_seq( + &token::OpenDelim(token::Paren), + &token::CloseDelim(token::Paren), + SeqSep::trailing_allowed(token::Comma), + |p| Ok(p.parse_expr()?) + )?; + args.insert(0, self_arg); + + let span = lo.to(self.prev_span); + self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new()) + } + _ => { + // Field access `expr.f` + if let Some(args) = segment.args { + self.span_err(args.span(), + "field expressions may not have generic arguments"); + } + + let span = lo.to(self.prev_span); + self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new()) + } + }) + } + + /// This function checks if there are trailing angle brackets and produces + /// a diagnostic to suggest removing them. + /// + /// ```ignore (diagnostic) + /// let _ = vec![1, 2, 3].into_iter().collect::<Vec<usize>>>>(); + /// ^^ help: remove extra angle brackets + /// ``` + fn check_trailing_angle_brackets(&mut self, segment: &PathSegment, end: token::Token) { + // This function is intended to be invoked after parsing a path segment where there are two + // cases: + // + // 1. A specific token is expected after the path segment. + // eg. `x.foo(`, `x.foo::<u32>(` (parenthesis - method call), + // `Foo::`, or `Foo::<Bar>::` (mod sep - continued path). + // 2. No specific token is expected after the path segment. + // eg. `x.foo` (field access) + // + // This function is called after parsing `.foo` and before parsing the token `end` (if + // present). This includes any angle bracket arguments, such as `.foo::<u32>` or + // `Foo::<Bar>`. + + // We only care about trailing angle brackets if we previously parsed angle bracket + // arguments. This helps stop us incorrectly suggesting that extra angle brackets be + // removed in this case: + // + // `x.foo >> (3)` (where `x.foo` is a `u32` for example) + // + // This case is particularly tricky as we won't notice it just looking at the tokens - + // it will appear the same (in terms of upcoming tokens) as below (since the `::<u32>` will + // have already been parsed): + // + // `x.foo::<u32>>>(3)` + let parsed_angle_bracket_args = segment.args + .as_ref() + .map(|args| args.is_angle_bracketed()) + .unwrap_or(false); + + debug!( + "check_trailing_angle_brackets: parsed_angle_bracket_args={:?}", + parsed_angle_bracket_args, + ); + if !parsed_angle_bracket_args { + return; + } + + // Keep the span at the start so we can highlight the sequence of `>` characters to be + // removed. + let lo = self.span; + + // We need to look-ahead to see if we have `>` characters without moving the cursor forward + // (since we might have the field access case and the characters we're eating are + // actual operators and not trailing characters - ie `x.foo >> 3`). + let mut position = 0; + + // We can encounter `>` or `>>` tokens in any order, so we need to keep track of how + // many of each (so we can correctly pluralize our error messages) and continue to + // advance. + let mut number_of_shr = 0; + let mut number_of_gt = 0; + while self.look_ahead(position, |t| { + trace!("check_trailing_angle_brackets: t={:?}", t); + if *t == token::BinOp(token::BinOpToken::Shr) { + number_of_shr += 1; + true + } else if *t == token::Gt { + number_of_gt += 1; + true + } else { + false + } + }) { + position += 1; + } + + // If we didn't find any trailing `>` characters, then we have nothing to error about. + debug!( + "check_trailing_angle_brackets: number_of_gt={:?} number_of_shr={:?}", + number_of_gt, number_of_shr, + ); + if number_of_gt < 1 && number_of_shr < 1 { + return; + } + + // Finally, double check that we have our end token as otherwise this is the + // second case. + if self.look_ahead(position, |t| { + trace!("check_trailing_angle_brackets: t={:?}", t); + *t == end + }) { + // Eat from where we started until the end token so that parsing can continue + // as if we didn't have those extra angle brackets. + self.eat_to_tokens(&[&end]); + let span = lo.until(self.span); + + let plural = number_of_gt > 1 || number_of_shr >= 1; + self.diagnostic() + .struct_span_err( + span, + &format!("unmatched angle bracket{}", if plural { "s" } else { "" }), + ) + .span_suggestion( + span, + &format!("remove extra angle bracket{}", if plural { "s" } else { "" }), + String::new(), + Applicability::MachineApplicable, + ) + .emit(); + } + } + + fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> { + let mut e = e0; + let mut hi; + loop { + // expr? + while self.eat(&token::Question) { + let hi = self.prev_span; + e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new()); + } + + // expr.f + if self.eat(&token::Dot) { + match self.token { + token::Ident(..) => { + e = self.parse_dot_suffix(e, lo)?; + } + token::Literal(token::Integer(name), _) => { + let span = self.span; + self.bump(); + let field = ExprKind::Field(e, Ident::new(name, span)); + e = self.mk_expr(lo.to(span), field, ThinVec::new()); + } + token::Literal(token::Float(n), _suf) => { + self.bump(); + let fstr = n.as_str(); + let mut err = self.diagnostic() + .struct_span_err(self.prev_span, &format!("unexpected token: `{}`", n)); + err.span_label(self.prev_span, "unexpected token"); + if fstr.chars().all(|x| "0123456789.".contains(x)) { + let float = match fstr.parse::<f64>().ok() { + Some(f) => f, + None => continue, + }; + let sugg = pprust::to_string(|s| { + use crate::print::pprust::PrintState; + s.popen()?; + s.print_expr(&e)?; + s.s.word( ".")?; + s.print_usize(float.trunc() as usize)?; + s.pclose()?; + s.s.word(".")?; + s.s.word(fstr.splitn(2, ".").last().unwrap().to_string()) + }); + err.span_suggestion( + lo.to(self.prev_span), + "try parenthesizing the first index", + sugg, + Applicability::MachineApplicable + ); + } + return Err(err); + + } + _ => { + // FIXME Could factor this out into non_fatal_unexpected or something. + let actual = self.this_token_to_string(); + self.span_err(self.span, &format!("unexpected token: `{}`", actual)); + } + } + continue; + } + if self.expr_is_complete(&e) { break; } + match self.token { + // expr(...) + token::OpenDelim(token::Paren) => { + let es = self.parse_unspanned_seq( + &token::OpenDelim(token::Paren), + &token::CloseDelim(token::Paren), + SeqSep::trailing_allowed(token::Comma), + |p| Ok(p.parse_expr()?) + )?; + hi = self.prev_span; + + let nd = self.mk_call(e, es); + e = self.mk_expr(lo.to(hi), nd, ThinVec::new()); + } + + // expr[...] + // Could be either an index expression or a slicing expression. + token::OpenDelim(token::Bracket) => { + self.bump(); + let ix = self.parse_expr()?; + hi = self.span; + self.expect(&token::CloseDelim(token::Bracket))?; + let index = self.mk_index(e, ix); + e = self.mk_expr(lo.to(hi), index, ThinVec::new()) + } + _ => return Ok(e) + } + } + return Ok(e); + } + + crate fn process_potential_macro_variable(&mut self) { + let (token, span) = match self.token { + token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() && + self.look_ahead(1, |t| t.is_ident()) => { + self.bump(); + let name = match self.token { + token::Ident(ident, _) => ident, + _ => unreachable!() + }; + let mut err = self.fatal(&format!("unknown macro variable `{}`", name)); + err.span_label(self.span, "unknown macro variable"); + err.emit(); + self.bump(); + return + } + token::Interpolated(ref nt) => { + self.meta_var_span = Some(self.span); + // Interpolated identifier and lifetime tokens are replaced with usual identifier + // and lifetime tokens, so the former are never encountered during normal parsing. + match **nt { + token::NtIdent(ident, is_raw) => (token::Ident(ident, is_raw), ident.span), + token::NtLifetime(ident) => (token::Lifetime(ident), ident.span), + _ => return, + } + } + _ => return, + }; + self.token = token; + self.span = span; + } + + /// Parses a single token tree from the input. + crate fn parse_token_tree(&mut self) -> TokenTree { + match self.token { + token::OpenDelim(..) => { + let frame = mem::replace(&mut self.token_cursor.frame, + self.token_cursor.stack.pop().unwrap()); + self.span = frame.span.entire(); + self.bump(); + TokenTree::Delimited( + frame.span, + frame.delim, + frame.tree_cursor.stream.into(), + ) + }, + token::CloseDelim(_) | token::Eof => unreachable!(), + _ => { + let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span); + self.bump(); + TokenTree::Token(span, token) + } + } + } + + // parse a stream of tokens into a list of TokenTree's, + // up to EOF. + pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> { + let mut tts = Vec::new(); + while self.token != token::Eof { + tts.push(self.parse_token_tree()); + } + Ok(tts) + } + + pub fn parse_tokens(&mut self) -> TokenStream { + let mut result = Vec::new(); + loop { + match self.token { + token::Eof | token::CloseDelim(..) => break, + _ => result.push(self.parse_token_tree().into()), + } + } + TokenStream::new(result) + } + + /// Parse a prefix-unary-operator expr + fn parse_prefix_expr(&mut self, + already_parsed_attrs: Option<ThinVec<Attribute>>) + -> PResult<'a, P<Expr>> { + let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?; + let lo = self.span; + // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr() + let (hi, ex) = match self.token { + token::Not => { + self.bump(); + let e = self.parse_prefix_expr(None); + let (span, e) = self.interpolated_or_expr_span(e)?; + (lo.to(span), self.mk_unary(UnOp::Not, e)) + } + // Suggest `!` for bitwise negation when encountering a `~` + token::Tilde => { + self.bump(); + let e = self.parse_prefix_expr(None); + let (span, e) = self.interpolated_or_expr_span(e)?; + let span_of_tilde = lo; + let mut err = self.diagnostic() + .struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator"); + err.span_suggestion_short( + span_of_tilde, + "use `!` to perform bitwise negation", + "!".to_owned(), + Applicability::MachineApplicable + ); + err.emit(); + (lo.to(span), self.mk_unary(UnOp::Not, e)) + } + token::BinOp(token::Minus) => { + self.bump(); + let e = self.parse_prefix_expr(None); + let (span, e) = self.interpolated_or_expr_span(e)?; + (lo.to(span), self.mk_unary(UnOp::Neg, e)) + } + token::BinOp(token::Star) => { + self.bump(); + let e = self.parse_prefix_expr(None); + let (span, e) = self.interpolated_or_expr_span(e)?; + (lo.to(span), self.mk_unary(UnOp::Deref, e)) + } + token::BinOp(token::And) | token::AndAnd => { + self.expect_and()?; + let m = self.parse_mutability(); + let e = self.parse_prefix_expr(None); + let (span, e) = self.interpolated_or_expr_span(e)?; + (lo.to(span), ExprKind::AddrOf(m, e)) + } + token::Ident(..) if self.token.is_keyword(keywords::In) => { + self.bump(); + let place = self.parse_expr_res( + Restrictions::NO_STRUCT_LITERAL, + None, + )?; + let blk = self.parse_block()?; + let span = blk.span; + let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new()); + (lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr)) + } + token::Ident(..) if self.token.is_keyword(keywords::Box) => { + self.bump(); + let e = self.parse_prefix_expr(None); + let (span, e) = self.interpolated_or_expr_span(e)?; + (lo.to(span), ExprKind::Box(e)) + } + token::Ident(..) if self.token.is_ident_named("not") => { + // `not` is just an ordinary identifier in Rust-the-language, + // but as `rustc`-the-compiler, we can issue clever diagnostics + // for confused users who really want to say `!` + let token_cannot_continue_expr = |t: &token::Token| match *t { + // These tokens can start an expression after `!`, but + // can't continue an expression after an ident + token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw), + token::Literal(..) | token::Pound => true, + token::Interpolated(ref nt) => match **nt { + token::NtIdent(..) | token::NtExpr(..) | + token::NtBlock(..) | token::NtPath(..) => true, + _ => false, + }, + _ => false + }; + let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr); + if cannot_continue_expr { + self.bump(); + // Emit the error ... + let mut err = self.diagnostic() + .struct_span_err(self.span, + &format!("unexpected {} after identifier", + self.this_token_descr())); + // span the `not` plus trailing whitespace to avoid + // trailing whitespace after the `!` in our suggestion + let to_replace = self.sess.source_map() + .span_until_non_whitespace(lo.to(self.span)); + err.span_suggestion_short( + to_replace, + "use `!` to perform logical negation", + "!".to_owned(), + Applicability::MachineApplicable + ); + err.emit(); + // —and recover! (just as if we were in the block + // for the `token::Not` arm) + let e = self.parse_prefix_expr(None); + let (span, e) = self.interpolated_or_expr_span(e)?; + (lo.to(span), self.mk_unary(UnOp::Not, e)) + } else { + return self.parse_dot_or_call_expr(Some(attrs)); + } + } + _ => { return self.parse_dot_or_call_expr(Some(attrs)); } + }; + return Ok(self.mk_expr(lo.to(hi), ex, attrs)); + } + + /// Parses an associative expression. + /// + /// This parses an expression accounting for associativity and precedence of the operators in + /// the expression. + #[inline] + fn parse_assoc_expr(&mut self, + already_parsed_attrs: Option<ThinVec<Attribute>>) + -> PResult<'a, P<Expr>> { + self.parse_assoc_expr_with(0, already_parsed_attrs.into()) + } + + /// Parses an associative expression with operators of at least `min_prec` precedence. + fn parse_assoc_expr_with(&mut self, + min_prec: usize, + lhs: LhsExpr) + -> PResult<'a, P<Expr>> { + let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs { + expr + } else { + let attrs = match lhs { + LhsExpr::AttributesParsed(attrs) => Some(attrs), + _ => None, + }; + if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token) { + return self.parse_prefix_range_expr(attrs); + } else { + self.parse_prefix_expr(attrs)? + } + }; + + if self.expr_is_complete(&lhs) { + // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071 + return Ok(lhs); + } + self.expected_tokens.push(TokenType::Operator); + while let Some(op) = AssocOp::from_token(&self.token) { + + // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what + // it refers to. Interpolated identifiers are unwrapped early and never show up here + // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process + // it as "interpolated", it doesn't change the answer for non-interpolated idents. + let lhs_span = match (self.prev_token_kind, &lhs.node) { + (PrevTokenKind::Interpolated, _) => self.prev_span, + (PrevTokenKind::Ident, &ExprKind::Path(None, ref path)) + if path.segments.len() == 1 => self.prev_span, + _ => lhs.span, + }; + + let cur_op_span = self.span; + let restrictions = if op.is_assign_like() { + self.restrictions & Restrictions::NO_STRUCT_LITERAL + } else { + self.restrictions + }; + if op.precedence() < min_prec { + break; + } + // Check for deprecated `...` syntax + if self.token == token::DotDotDot && op == AssocOp::DotDotEq { + self.err_dotdotdot_syntax(self.span); + } + + self.bump(); + if op.is_comparison() { + self.check_no_chained_comparison(&lhs, &op); + } + // Special cases: + if op == AssocOp::As { + lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?; + continue + } else if op == AssocOp::Colon { + lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) { + Ok(lhs) => lhs, + Err(mut err) => { + err.span_label(self.span, + "expecting a type here because of type ascription"); + let cm = self.sess.source_map(); + let cur_pos = cm.lookup_char_pos(self.span.lo()); + let op_pos = cm.lookup_char_pos(cur_op_span.hi()); + if cur_pos.line != op_pos.line { + err.span_suggestion( + cur_op_span, + "try using a semicolon", + ";".to_string(), + Applicability::MaybeIncorrect // speculative + ); + } + return Err(err); + } + }; + continue + } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq { + // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to + // generalise it to the Fixity::None code. + // + // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other + // two variants are handled with `parse_prefix_range_expr` call above. + let rhs = if self.is_at_start_of_range_notation_rhs() { + Some(self.parse_assoc_expr_with(op.precedence() + 1, + LhsExpr::NotYetParsed)?) + } else { + None + }; + let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs { + x.span + } else { + cur_op_span + }); + let limits = if op == AssocOp::DotDot { + RangeLimits::HalfOpen + } else { + RangeLimits::Closed + }; + + let r = self.mk_range(Some(lhs), rhs, limits)?; + lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new()); + break + } + + let rhs = match op.fixity() { + Fixity::Right => self.with_res( + restrictions - Restrictions::STMT_EXPR, + |this| { + this.parse_assoc_expr_with(op.precedence(), + LhsExpr::NotYetParsed) + }), + Fixity::Left => self.with_res( + restrictions - Restrictions::STMT_EXPR, + |this| { + this.parse_assoc_expr_with(op.precedence() + 1, + LhsExpr::NotYetParsed) + }), + // We currently have no non-associative operators that are not handled above by + // the special cases. The code is here only for future convenience. + Fixity::None => self.with_res( + restrictions - Restrictions::STMT_EXPR, + |this| { + this.parse_assoc_expr_with(op.precedence() + 1, + LhsExpr::NotYetParsed) + }), + }?; + + // Make sure that the span of the parent node is larger than the span of lhs and rhs, + // including the attributes. + let lhs_span = lhs + .attrs + .iter() + .filter(|a| a.style == AttrStyle::Outer) + .next() + .map_or(lhs_span, |a| a.span); + let span = lhs_span.to(rhs.span); + lhs = match op { + AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide | + AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor | + AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight | + AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual | + AssocOp::Greater | AssocOp::GreaterEqual => { + let ast_op = op.to_ast_binop().unwrap(); + let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs); + self.mk_expr(span, binary, ThinVec::new()) + } + AssocOp::Assign => + self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()), + AssocOp::ObsoleteInPlace => + self.mk_expr(span, ExprKind::ObsoleteInPlace(lhs, rhs), ThinVec::new()), + AssocOp::AssignOp(k) => { + let aop = match k { + token::Plus => BinOpKind::Add, + token::Minus => BinOpKind::Sub, + token::Star => BinOpKind::Mul, + token::Slash => BinOpKind::Div, + token::Percent => BinOpKind::Rem, + token::Caret => BinOpKind::BitXor, + token::And => BinOpKind::BitAnd, + token::Or => BinOpKind::BitOr, + token::Shl => BinOpKind::Shl, + token::Shr => BinOpKind::Shr, + }; + let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs); + self.mk_expr(span, aopexpr, ThinVec::new()) + } + AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => { + self.bug("AssocOp should have been handled by special case") + } + }; + + if op.fixity() == Fixity::None { break } + } + Ok(lhs) + } + + fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span, + expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind) + -> PResult<'a, P<Expr>> { + let mk_expr = |this: &mut Self, rhs: P<Ty>| { + this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new()) + }; + + // Save the state of the parser before parsing type normally, in case there is a + // LessThan comparison after this cast. + let parser_snapshot_before_type = self.clone(); + match self.parse_ty_no_plus() { + Ok(rhs) => { + Ok(mk_expr(self, rhs)) + } + Err(mut type_err) => { + // Rewind to before attempting to parse the type with generics, to recover + // from situations like `x as usize < y` in which we first tried to parse + // `usize < y` as a type with generic arguments. + let parser_snapshot_after_type = self.clone(); + mem::replace(self, parser_snapshot_before_type); + + match self.parse_path(PathStyle::Expr) { + Ok(path) => { + let (op_noun, op_verb) = match self.token { + token::Lt => ("comparison", "comparing"), + token::BinOp(token::Shl) => ("shift", "shifting"), + _ => { + // We can end up here even without `<` being the next token, for + // example because `parse_ty_no_plus` returns `Err` on keywords, + // but `parse_path` returns `Ok` on them due to error recovery. + // Return original error and parser state. + mem::replace(self, parser_snapshot_after_type); + return Err(type_err); + } + }; + + // Successfully parsed the type path leaving a `<` yet to parse. + type_err.cancel(); + + // Report non-fatal diagnostics, keep `x as usize` as an expression + // in AST and continue parsing. + let msg = format!("`<` is interpreted as a start of generic \ + arguments for `{}`, not a {}", path, op_noun); + let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg); + err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span), + "interpreted as generic arguments"); + err.span_label(self.span, format!("not interpreted as {}", op_noun)); + + let expr = mk_expr(self, P(Ty { + span: path.span, + node: TyKind::Path(None, path), + id: ast::DUMMY_NODE_ID + })); + + let expr_str = self.sess.source_map().span_to_snippet(expr.span) + .unwrap_or_else(|_| pprust::expr_to_string(&expr)); + err.span_suggestion( + expr.span, + &format!("try {} the cast value", op_verb), + format!("({})", expr_str), + Applicability::MachineApplicable + ); + err.emit(); + + Ok(expr) + } + Err(mut path_err) => { + // Couldn't parse as a path, return original error and parser state. + path_err.cancel(); + mem::replace(self, parser_snapshot_after_type); + Err(type_err) + } + } + } + } + } + + /// Produce an error if comparison operators are chained (RFC #558). + /// We only need to check lhs, not rhs, because all comparison ops + /// have same precedence and are left-associative + fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) { + debug_assert!(outer_op.is_comparison(), + "check_no_chained_comparison: {:?} is not comparison", + outer_op); + match lhs.node { + ExprKind::Binary(op, _, _) if op.node.is_comparison() => { + // respan to include both operators + let op_span = op.span.to(self.span); + let mut err = self.diagnostic().struct_span_err(op_span, + "chained comparison operators require parentheses"); + if op.node == BinOpKind::Lt && + *outer_op == AssocOp::Less || // Include `<` to provide this recommendation + *outer_op == AssocOp::Greater // even in a case like the following: + { // Foo<Bar<Baz<Qux, ()>>> + err.help( + "use `::<...>` instead of `<...>` if you meant to specify type arguments"); + err.help("or use `(...)` if you meant to specify fn arguments"); + } + err.emit(); + } + _ => {} + } + } + + /// Parse prefix-forms of range notation: `..expr`, `..`, `..=expr` + fn parse_prefix_range_expr(&mut self, + already_parsed_attrs: Option<ThinVec<Attribute>>) + -> PResult<'a, P<Expr>> { + // Check for deprecated `...` syntax + if self.token == token::DotDotDot { + self.err_dotdotdot_syntax(self.span); + } + + debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token), + "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq", + self.token); + let tok = self.token.clone(); + let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?; + let lo = self.span; + let mut hi = self.span; + self.bump(); + let opt_end = if self.is_at_start_of_range_notation_rhs() { + // RHS must be parsed with more associativity than the dots. + let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1; + Some(self.parse_assoc_expr_with(next_prec, + LhsExpr::NotYetParsed) + .map(|x|{ + hi = x.span; + x + })?) + } else { + None + }; + let limits = if tok == token::DotDot { + RangeLimits::HalfOpen + } else { + RangeLimits::Closed + }; + + let r = self.mk_range(None, opt_end, limits)?; + Ok(self.mk_expr(lo.to(hi), r, attrs)) + } + + fn is_at_start_of_range_notation_rhs(&self) -> bool { + if self.token.can_begin_expr() { + // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`. + if self.token == token::OpenDelim(token::Brace) { + return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL); + } + true + } else { + false + } + } + + /// Parses an `if` or `if let` expression (`if` token already eaten). + fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> { + if self.check_keyword(keywords::Let) { + return self.parse_if_let_expr(attrs); + } + let lo = self.prev_span; + let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; + + // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then + // verify that the last statement is either an implicit return (no `;`) or an explicit + // return. This won't catch blocks with an explicit `return`, but that would be caught by + // the dead code lint. + if self.eat_keyword(keywords::Else) || !cond.returns() { + let sp = self.sess.source_map().next_point(lo); + let mut err = self.diagnostic() + .struct_span_err(sp, "missing condition for `if` statemement"); + err.span_label(sp, "expected if condition here"); + return Err(err) + } + let not_block = self.token != token::OpenDelim(token::Brace); + let thn = self.parse_block().map_err(|mut err| { + if not_block { + err.span_label(lo, "this `if` statement has a condition, but no block"); + } + err + })?; + let mut els: Option<P<Expr>> = None; + let mut hi = thn.span; + if self.eat_keyword(keywords::Else) { + let elexpr = self.parse_else_expr()?; + hi = elexpr.span; + els = Some(elexpr); + } + Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs)) + } + + /// Parses an `if let` expression (`if` token already eaten). + fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>) + -> PResult<'a, P<Expr>> { + let lo = self.prev_span; + self.expect_keyword(keywords::Let)?; + let pats = self.parse_pats()?; + self.expect(&token::Eq)?; + let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; + let thn = self.parse_block()?; + let (hi, els) = if self.eat_keyword(keywords::Else) { + let expr = self.parse_else_expr()?; + (expr.span, Some(expr)) + } else { + (thn.span, None) + }; + Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs)) + } + + /// Parses `move |args| expr`. + fn parse_lambda_expr(&mut self, + attrs: ThinVec<Attribute>) + -> PResult<'a, P<Expr>> + { + let lo = self.span; + let movability = if self.eat_keyword(keywords::Static) { + Movability::Static + } else { + Movability::Movable + }; + let asyncness = if self.span.rust_2018() { + self.parse_asyncness() + } else { + IsAsync::NotAsync + }; + let capture_clause = if self.eat_keyword(keywords::Move) { + CaptureBy::Value + } else { + CaptureBy::Ref + }; + let decl = self.parse_fn_block_decl()?; + let decl_hi = self.prev_span; + let body = match decl.output { + FunctionRetTy::Default(_) => { + let restrictions = self.restrictions - Restrictions::STMT_EXPR; + self.parse_expr_res(restrictions, None)? + }, + _ => { + // If an explicit return type is given, require a + // block to appear (RFC 968). + let body_lo = self.span; + self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())? + } + }; + + Ok(self.mk_expr( + lo.to(body.span), + ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)), + attrs)) + } + + // `else` token already eaten + fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> { + if self.eat_keyword(keywords::If) { + return self.parse_if_expr(ThinVec::new()); + } else { + let blk = self.parse_block()?; + return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new())); + } + } + + /// Parse a 'for' .. 'in' expression ('for' token already eaten) + fn parse_for_expr(&mut self, opt_label: Option<Label>, + span_lo: Span, + mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> { + // Parse: `for <src_pat> in <src_expr> <src_loop_block>` + + let pat = self.parse_top_level_pat()?; + if !self.eat_keyword(keywords::In) { + let in_span = self.prev_span.between(self.span); + let mut err = self.sess.span_diagnostic + .struct_span_err(in_span, "missing `in` in `for` loop"); + err.span_suggestion_short( + in_span, "try adding `in` here", " in ".into(), + // has been misleading, at least in the past (closed Issue #48492) + Applicability::MaybeIncorrect + ); + err.emit(); + } + let in_span = self.prev_span; + if self.eat_keyword(keywords::In) { + // a common typo: `for _ in in bar {}` + let mut err = self.sess.span_diagnostic.struct_span_err( + self.prev_span, + "expected iterable, found keyword `in`", + ); + err.span_suggestion_short( + in_span.until(self.prev_span), + "remove the duplicated `in`", + String::new(), + Applicability::MachineApplicable, + ); + err.note("if you meant to use emplacement syntax, it is obsolete (for now, anyway)"); + err.note("for more information on the status of emplacement syntax, see <\ + https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>"); + err.emit(); + } + let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; + let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?; + attrs.extend(iattrs); + + let hi = self.prev_span; + Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs)) + } + + /// Parses a `while` or `while let` expression (`while` token already eaten). + fn parse_while_expr(&mut self, opt_label: Option<Label>, + span_lo: Span, + mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> { + if self.token.is_keyword(keywords::Let) { + return self.parse_while_let_expr(opt_label, span_lo, attrs); + } + let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; + let (iattrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(iattrs); + let span = span_lo.to(body.span); + return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs)); + } + + /// Parses a `while let` expression (`while` token already eaten). + fn parse_while_let_expr(&mut self, opt_label: Option<Label>, + span_lo: Span, + mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> { + self.expect_keyword(keywords::Let)?; + let pats = self.parse_pats()?; + self.expect(&token::Eq)?; + let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; + let (iattrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(iattrs); + let span = span_lo.to(body.span); + return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs)); + } + + // parse `loop {...}`, `loop` token already eaten + fn parse_loop_expr(&mut self, opt_label: Option<Label>, + span_lo: Span, + mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> { + let (iattrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(iattrs); + let span = span_lo.to(body.span); + Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs)) + } + + /// Parses an `async move {...}` expression. + pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>) + -> PResult<'a, P<Expr>> + { + let span_lo = self.span; + self.expect_keyword(keywords::Async)?; + let capture_clause = if self.eat_keyword(keywords::Move) { + CaptureBy::Value + } else { + CaptureBy::Ref + }; + let (iattrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(iattrs); + Ok(self.mk_expr( + span_lo.to(body.span), + ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs)) + } + + /// Parses a `try {...}` expression (`try` token already eaten). + fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>) + -> PResult<'a, P<Expr>> + { + let (iattrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(iattrs); + Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs)) + } + + // `match` token already eaten + fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> { + let match_span = self.prev_span; + let lo = self.prev_span; + let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, + None)?; + if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) { + if self.token == token::Token::Semi { + e.span_suggestion_short( + match_span, + "try removing this `match`", + String::new(), + Applicability::MaybeIncorrect // speculative + ); + } + return Err(e) + } + attrs.extend(self.parse_inner_attributes()?); + + let mut arms: Vec<Arm> = Vec::new(); + while self.token != token::CloseDelim(token::Brace) { + match self.parse_arm() { + Ok(arm) => arms.push(arm), + Err(mut e) => { + // Recover by skipping to the end of the block. + e.emit(); + self.recover_stmt(); + let span = lo.to(self.span); + if self.token == token::CloseDelim(token::Brace) { + self.bump(); + } + return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs)); + } + } + } + let hi = self.span; + self.bump(); + return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs)); + } + + crate fn parse_arm(&mut self) -> PResult<'a, Arm> { + maybe_whole!(self, NtArm, |x| x); + + let attrs = self.parse_outer_attributes()?; + let pats = self.parse_pats()?; + let guard = if self.eat_keyword(keywords::If) { + Some(Guard::If(self.parse_expr()?)) + } else { + None + }; + let arrow_span = self.span; + self.expect(&token::FatArrow)?; + let arm_start_span = self.span; + + let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None) + .map_err(|mut err| { + err.span_label(arrow_span, "while parsing the `match` arm starting here"); + err + })?; + + let require_comma = classify::expr_requires_semi_to_be_stmt(&expr) + && self.token != token::CloseDelim(token::Brace); + + if require_comma { + let cm = self.sess.source_map(); + self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)]) + .map_err(|mut err| { + match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) { + (Ok(ref expr_lines), Ok(ref arm_start_lines)) + if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col + && expr_lines.lines.len() == 2 + && self.token == token::FatArrow => { + // We check whether there's any trailing code in the parse span, + // if there isn't, we very likely have the following: + // + // X | &Y => "y" + // | -- - missing comma + // | | + // | arrow_span + // X | &X => "x" + // | - ^^ self.span + // | | + // | parsed until here as `"y" & X` + err.span_suggestion_short( + cm.next_point(arm_start_span), + "missing a comma here to end this `match` arm", + ",".to_owned(), + Applicability::MachineApplicable + ); + } + _ => { + err.span_label(arrow_span, + "while parsing the `match` arm starting here"); + } + } + err + })?; + } else { + self.eat(&token::Comma); + } + + Ok(ast::Arm { + attrs, + pats, + guard, + body: expr, + }) + } + + /// Parses an expression. + #[inline] + pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> { + self.parse_expr_res(Restrictions::empty(), None) + } + + /// Evaluates the closure with restrictions in place. + /// + /// Afters the closure is evaluated, restrictions are reset. + fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T + where F: FnOnce(&mut Self) -> T + { + let old = self.restrictions; + self.restrictions = r; + let r = f(self); + self.restrictions = old; + return r; + + } + + /// Parses an expression, subject to the given restrictions. + #[inline] + fn parse_expr_res(&mut self, r: Restrictions, + already_parsed_attrs: Option<ThinVec<Attribute>>) + -> PResult<'a, P<Expr>> { + self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs)) + } + + /// Parses the RHS of a local variable declaration (e.g., '= 14;'). + fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> { + if self.eat(&token::Eq) { + Ok(Some(self.parse_expr()?)) + } else if skip_eq { + Ok(Some(self.parse_expr()?)) + } else { + Ok(None) + } + } + + /// Parses patterns, separated by '|' s. + fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> { + // Allow a '|' before the pats (RFC 1925 + RFC 2530) + self.eat(&token::BinOp(token::Or)); + + let mut pats = Vec::new(); + loop { + pats.push(self.parse_top_level_pat()?); + + if self.token == token::OrOr { + let mut err = self.struct_span_err(self.span, + "unexpected token `||` after pattern"); + err.span_suggestion( + self.span, + "use a single `|` to specify multiple patterns", + "|".to_owned(), + Applicability::MachineApplicable + ); + err.emit(); + self.bump(); + } else if self.eat(&token::BinOp(token::Or)) { + // This is a No-op. Continue the loop to parse the next + // pattern. + } else { + return Ok(pats); + } + }; + } + + // Parses a parenthesized list of patterns like + // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns: + // - a vector of the patterns that were parsed + // - an option indicating the index of the `..` element + // - a boolean indicating whether a trailing comma was present. + // Trailing commas are significant because (p) and (p,) are different patterns. + fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> { + self.expect(&token::OpenDelim(token::Paren))?; + let result = self.parse_pat_list()?; + self.expect(&token::CloseDelim(token::Paren))?; + Ok(result) + } + + fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> { + let mut fields = Vec::new(); + let mut ddpos = None; + let mut trailing_comma = false; + loop { + if self.eat(&token::DotDot) { + if ddpos.is_none() { + ddpos = Some(fields.len()); + } else { + // Emit a friendly error, ignore `..` and continue parsing + self.struct_span_err( + self.prev_span, + "`..` can only be used once per tuple or tuple struct pattern", + ) + .span_label(self.prev_span, "can only be used once per pattern") + .emit(); + } + } else if !self.check(&token::CloseDelim(token::Paren)) { + fields.push(self.parse_pat(None)?); + } else { + break + } + + trailing_comma = self.eat(&token::Comma); + if !trailing_comma { + break + } + } + + if ddpos == Some(fields.len()) && trailing_comma { + // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed. + let msg = "trailing comma is not permitted after `..`"; + self.struct_span_err(self.prev_span, msg) + .span_label(self.prev_span, msg) + .emit(); + } + + Ok((fields, ddpos, trailing_comma)) + } + + fn parse_pat_vec_elements( + &mut self, + ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> { + let mut before = Vec::new(); + let mut slice = None; + let mut after = Vec::new(); + let mut first = true; + let mut before_slice = true; + + while self.token != token::CloseDelim(token::Bracket) { + if first { + first = false; + } else { + self.expect(&token::Comma)?; + + if self.token == token::CloseDelim(token::Bracket) + && (before_slice || !after.is_empty()) { + break + } + } + + if before_slice { + if self.eat(&token::DotDot) { + + if self.check(&token::Comma) || + self.check(&token::CloseDelim(token::Bracket)) { + slice = Some(P(Pat { + id: ast::DUMMY_NODE_ID, + node: PatKind::Wild, + span: self.prev_span, + })); + before_slice = false; + } + continue + } + } + + let subpat = self.parse_pat(None)?; + if before_slice && self.eat(&token::DotDot) { + slice = Some(subpat); + before_slice = false; + } else if before_slice { + before.push(subpat); + } else { + after.push(subpat); + } + } + + Ok((before, slice, after)) + } + + fn parse_pat_field( + &mut self, + lo: Span, + attrs: Vec<Attribute> + ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> { + // Check if a colon exists one ahead. This means we're parsing a fieldname. + let hi; + let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) { + // Parsing a pattern of the form "fieldname: pat" + let fieldname = self.parse_field_name()?; + self.bump(); + let pat = self.parse_pat(None)?; + hi = pat.span; + (pat, fieldname, false) + } else { + // Parsing a pattern of the form "(box) (ref) (mut) fieldname" + let is_box = self.eat_keyword(keywords::Box); + let boxed_span = self.span; + let is_ref = self.eat_keyword(keywords::Ref); + let is_mut = self.eat_keyword(keywords::Mut); + let fieldname = self.parse_ident()?; + hi = self.prev_span; + + let bind_type = match (is_ref, is_mut) { + (true, true) => BindingMode::ByRef(Mutability::Mutable), + (true, false) => BindingMode::ByRef(Mutability::Immutable), + (false, true) => BindingMode::ByValue(Mutability::Mutable), + (false, false) => BindingMode::ByValue(Mutability::Immutable), + }; + let fieldpat = P(Pat { + id: ast::DUMMY_NODE_ID, + node: PatKind::Ident(bind_type, fieldname, None), + span: boxed_span.to(hi), + }); + + let subpat = if is_box { + P(Pat { + id: ast::DUMMY_NODE_ID, + node: PatKind::Box(fieldpat), + span: lo.to(hi), + }) + } else { + fieldpat + }; + (subpat, fieldname, true) + }; + + Ok(source_map::Spanned { + span: lo.to(hi), + node: ast::FieldPat { + ident: fieldname, + pat: subpat, + is_shorthand, + attrs: attrs.into(), + } + }) + } + + /// Parses the fields of a struct-like pattern. + fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> { + let mut fields = Vec::new(); + let mut etc = false; + let mut ate_comma = true; + let mut delayed_err: Option<DiagnosticBuilder<'a>> = None; + let mut etc_span = None; + + while self.token != token::CloseDelim(token::Brace) { + let attrs = self.parse_outer_attributes()?; + let lo = self.span; + + // check that a comma comes after every field + if !ate_comma { + let err = self.struct_span_err(self.prev_span, "expected `,`"); + if let Some(mut delayed) = delayed_err { + delayed.emit(); + } + return Err(err); + } + ate_comma = false; + + if self.check(&token::DotDot) || self.token == token::DotDotDot { + etc = true; + let mut etc_sp = self.span; + + if self.token == token::DotDotDot { // Issue #46718 + // Accept `...` as if it were `..` to avoid further errors + let mut err = self.struct_span_err(self.span, + "expected field pattern, found `...`"); + err.span_suggestion( + self.span, + "to omit remaining fields, use one fewer `.`", + "..".to_owned(), + Applicability::MachineApplicable + ); + err.emit(); + } + self.bump(); // `..` || `...` + + if self.token == token::CloseDelim(token::Brace) { + etc_span = Some(etc_sp); + break; + } + let token_str = self.this_token_descr(); + let mut err = self.fatal(&format!("expected `}}`, found {}", token_str)); + + err.span_label(self.span, "expected `}`"); + let mut comma_sp = None; + if self.token == token::Comma { // Issue #49257 + etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span)); + err.span_label(etc_sp, + "`..` must be at the end and cannot have a trailing comma"); + comma_sp = Some(self.span); + self.bump(); + ate_comma = true; + } + + etc_span = Some(etc_sp.until(self.span)); + if self.token == token::CloseDelim(token::Brace) { + // If the struct looks otherwise well formed, recover and continue. + if let Some(sp) = comma_sp { + err.span_suggestion_short( + sp, + "remove this comma", + String::new(), + Applicability::MachineApplicable, + ); + } + err.emit(); + break; + } else if self.token.is_ident() && ate_comma { + // Accept fields coming after `..,`. + // This way we avoid "pattern missing fields" errors afterwards. + // We delay this error until the end in order to have a span for a + // suggested fix. + if let Some(mut delayed_err) = delayed_err { + delayed_err.emit(); + return Err(err); + } else { + delayed_err = Some(err); + } + } else { + if let Some(mut err) = delayed_err { + err.emit(); + } + return Err(err); + } + } + + fields.push(match self.parse_pat_field(lo, attrs) { + Ok(field) => field, + Err(err) => { + if let Some(mut delayed_err) = delayed_err { + delayed_err.emit(); + } + return Err(err); + } + }); + ate_comma = self.eat(&token::Comma); + } + + if let Some(mut err) = delayed_err { + if let Some(etc_span) = etc_span { + err.multipart_suggestion( + "move the `..` to the end of the field list", + vec![ + (etc_span, String::new()), + (self.span, format!("{}.. }}", if ate_comma { "" } else { ", " })), + ], + Applicability::MachineApplicable, + ); + } + err.emit(); + } + return Ok((fields, etc)); + } + + fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> { + if self.token.is_path_start() { + let lo = self.span; + let (qself, path) = if self.eat_lt() { + // Parse a qualified path + let (qself, path) = self.parse_qpath(PathStyle::Expr)?; + (Some(qself), path) + } else { + // Parse an unqualified path + (None, self.parse_path(PathStyle::Expr)?) + }; + let hi = self.prev_span; + Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new())) + } else { + self.parse_literal_maybe_minus() + } + } + + // helper function to decide whether to parse as ident binding or to try to do + // something more complex like range patterns + fn parse_as_ident(&mut self) -> bool { + self.look_ahead(1, |t| match *t { + token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) | + token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false), + // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the + // range pattern branch + token::DotDot => None, + _ => Some(true), + }).unwrap_or_else(|| self.look_ahead(2, |t| match *t { + token::Comma | token::CloseDelim(token::Bracket) => true, + _ => false, + })) + } + + /// A wrapper around `parse_pat` with some special error handling for the + /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast + /// to subpatterns within such). + fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> { + let pat = self.parse_pat(None)?; + if self.token == token::Comma { + // An unexpected comma after a top-level pattern is a clue that the + // user (perhaps more accustomed to some other language) forgot the + // parentheses in what should have been a tuple pattern; return a + // suggestion-enhanced error here rather than choking on the comma + // later. + let comma_span = self.span; + self.bump(); + if let Err(mut err) = self.parse_pat_list() { + // We didn't expect this to work anyway; we just wanted + // to advance to the end of the comma-sequence so we know + // the span to suggest parenthesizing + err.cancel(); + } + let seq_span = pat.span.to(self.prev_span); + let mut err = self.struct_span_err(comma_span, + "unexpected `,` in pattern"); + if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) { + err.span_suggestion( + seq_span, + "try adding parentheses to match on a tuple..", + format!("({})", seq_snippet), + Applicability::MachineApplicable + ).span_suggestion( + seq_span, + "..or a vertical bar to match on multiple alternatives", + format!("{}", seq_snippet.replace(",", " |")), + Applicability::MachineApplicable + ); + } + return Err(err); + } + Ok(pat) + } + + /// Parses a pattern. + pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> { + self.parse_pat_with_range_pat(true, expected) + } + + /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are + /// allowed). + fn parse_pat_with_range_pat( + &mut self, + allow_range_pat: bool, + expected: Option<&'static str>, + ) -> PResult<'a, P<Pat>> { + maybe_whole!(self, NtPat, |x| x); + + let lo = self.span; + let pat; + match self.token { + token::BinOp(token::And) | token::AndAnd => { + // Parse &pat / &mut pat + self.expect_and()?; + let mutbl = self.parse_mutability(); + if let token::Lifetime(ident) = self.token { + let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern", + ident)); + err.span_label(self.span, "unexpected lifetime"); + return Err(err); + } + let subpat = self.parse_pat_with_range_pat(false, expected)?; + pat = PatKind::Ref(subpat, mutbl); + } + token::OpenDelim(token::Paren) => { + // Parse (pat,pat,pat,...) as tuple pattern + let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?; + pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma { + PatKind::Paren(fields.into_iter().nth(0).unwrap()) + } else { + PatKind::Tuple(fields, ddpos) + }; + } + token::OpenDelim(token::Bracket) => { + // Parse [pat,pat,...] as slice pattern + self.bump(); + let (before, slice, after) = self.parse_pat_vec_elements()?; + self.expect(&token::CloseDelim(token::Bracket))?; + pat = PatKind::Slice(before, slice, after); + } + // At this point, token != &, &&, (, [ + _ => if self.eat_keyword(keywords::Underscore) { + // Parse _ + pat = PatKind::Wild; + } else if self.eat_keyword(keywords::Mut) { + // Parse mut ident @ pat / mut ref ident @ pat + let mutref_span = self.prev_span.to(self.span); + let binding_mode = if self.eat_keyword(keywords::Ref) { + self.diagnostic() + .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect") + .span_suggestion( + mutref_span, + "try switching the order", + "ref mut".into(), + Applicability::MachineApplicable + ).emit(); + BindingMode::ByRef(Mutability::Mutable) + } else { + BindingMode::ByValue(Mutability::Mutable) + }; + pat = self.parse_pat_ident(binding_mode)?; + } else if self.eat_keyword(keywords::Ref) { + // Parse ref ident @ pat / ref mut ident @ pat + let mutbl = self.parse_mutability(); + pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?; + } else if self.eat_keyword(keywords::Box) { + // Parse box pat + let subpat = self.parse_pat_with_range_pat(false, None)?; + pat = PatKind::Box(subpat); + } else if self.token.is_ident() && !self.token.is_reserved_ident() && + self.parse_as_ident() { + // Parse ident @ pat + // This can give false positives and parse nullary enums, + // they are dealt with later in resolve + let binding_mode = BindingMode::ByValue(Mutability::Immutable); + pat = self.parse_pat_ident(binding_mode)?; + } else if self.token.is_path_start() { + // Parse pattern starting with a path + let (qself, path) = if self.eat_lt() { + // Parse a qualified path + let (qself, path) = self.parse_qpath(PathStyle::Expr)?; + (Some(qself), path) + } else { + // Parse an unqualified path + (None, self.parse_path(PathStyle::Expr)?) + }; + match self.token { + token::Not if qself.is_none() => { + // Parse macro invocation + self.bump(); + let (delim, tts) = self.expect_delimited_token_tree()?; + let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim }); + pat = PatKind::Mac(mac); + } + token::DotDotDot | token::DotDotEq | token::DotDot => { + let end_kind = match self.token { + token::DotDot => RangeEnd::Excluded, + token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot), + token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq), + _ => panic!("can only parse `..`/`...`/`..=` for ranges \ + (checked above)"), + }; + let op_span = self.span; + // Parse range + let span = lo.to(self.prev_span); + let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new()); + self.bump(); + let end = self.parse_pat_range_end()?; + let op = Spanned { span: op_span, node: end_kind }; + pat = PatKind::Range(begin, end, op); + } + token::OpenDelim(token::Brace) => { + if qself.is_some() { + let msg = "unexpected `{` after qualified path"; + let mut err = self.fatal(msg); + err.span_label(self.span, msg); + return Err(err); + } + // Parse struct pattern + self.bump(); + let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| { + e.emit(); + self.recover_stmt(); + (vec![], false) + }); + self.bump(); + pat = PatKind::Struct(path, fields, etc); + } + token::OpenDelim(token::Paren) => { + if qself.is_some() { + let msg = "unexpected `(` after qualified path"; + let mut err = self.fatal(msg); + err.span_label(self.span, msg); + return Err(err); + } + // Parse tuple struct or enum pattern + let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?; + pat = PatKind::TupleStruct(path, fields, ddpos) + } + _ => pat = PatKind::Path(qself, path), + } + } else { + // Try to parse everything else as literal with optional minus + match self.parse_literal_maybe_minus() { + Ok(begin) => { + let op_span = self.span; + if self.check(&token::DotDot) || self.check(&token::DotDotEq) || + self.check(&token::DotDotDot) { + let end_kind = if self.eat(&token::DotDotDot) { + RangeEnd::Included(RangeSyntax::DotDotDot) + } else if self.eat(&token::DotDotEq) { + RangeEnd::Included(RangeSyntax::DotDotEq) + } else if self.eat(&token::DotDot) { + RangeEnd::Excluded + } else { + panic!("impossible case: we already matched \ + on a range-operator token") + }; + let end = self.parse_pat_range_end()?; + let op = Spanned { span: op_span, node: end_kind }; + pat = PatKind::Range(begin, end, op); + } else { + pat = PatKind::Lit(begin); + } + } + Err(mut err) => { + self.cancel(&mut err); + let expected = expected.unwrap_or("pattern"); + let msg = format!( + "expected {}, found {}", + expected, + self.this_token_descr(), + ); + let mut err = self.fatal(&msg); + err.span_label(self.span, format!("expected {}", expected)); + return Err(err); + } + } + } + } + + let pat = Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID }; + let pat = self.maybe_recover_from_bad_qpath(pat, true)?; + + if !allow_range_pat { + match pat.node { + PatKind::Range( + _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. } + ) => {}, + PatKind::Range(..) => { + let mut err = self.struct_span_err( + pat.span, + "the range pattern here has ambiguous interpretation", + ); + err.span_suggestion( + pat.span, + "add parentheses to clarify the precedence", + format!("({})", pprust::pat_to_string(&pat)), + // "ambiguous interpretation" implies that we have to be guessing + Applicability::MaybeIncorrect + ); + return Err(err); + } + _ => {} + } + } + + Ok(P(pat)) + } + + /// Parses `ident` or `ident @ pat`. + /// used by the copy foo and ref foo patterns to give a good + /// error message when parsing mistakes like `ref foo(a, b)`. + fn parse_pat_ident(&mut self, + binding_mode: ast::BindingMode) + -> PResult<'a, PatKind> { + let ident = self.parse_ident()?; + let sub = if self.eat(&token::At) { + Some(self.parse_pat(Some("binding pattern"))?) + } else { + None + }; + + // just to be friendly, if they write something like + // ref Some(i) + // we end up here with ( as the current token. This shortly + // leads to a parse error. Note that if there is no explicit + // binding mode then we do not end up here, because the lookahead + // will direct us over to parse_enum_variant() + if self.token == token::OpenDelim(token::Paren) { + return Err(self.span_fatal( + self.prev_span, + "expected identifier, found enum pattern")) + } + + Ok(PatKind::Ident(binding_mode, ident, sub)) + } + + /// Parses a local variable declaration. + fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> { + let lo = self.prev_span; + let pat = self.parse_top_level_pat()?; + + let (err, ty) = if self.eat(&token::Colon) { + // Save the state of the parser before parsing type normally, in case there is a `:` + // instead of an `=` typo. + let parser_snapshot_before_type = self.clone(); + let colon_sp = self.prev_span; + match self.parse_ty() { + Ok(ty) => (None, Some(ty)), + Err(mut err) => { + // Rewind to before attempting to parse the type and continue parsing + let parser_snapshot_after_type = self.clone(); + mem::replace(self, parser_snapshot_before_type); + + let snippet = self.sess.source_map().span_to_snippet(pat.span).unwrap(); + err.span_label(pat.span, format!("while parsing the type for `{}`", snippet)); + (Some((parser_snapshot_after_type, colon_sp, err)), None) + } + } + } else { + (None, None) + }; + let init = match (self.parse_initializer(err.is_some()), err) { + (Ok(init), None) => { // init parsed, ty parsed + init + } + (Ok(init), Some((_, colon_sp, mut err))) => { // init parsed, ty error + // Could parse the type as if it were the initializer, it is likely there was a + // typo in the code: `:` instead of `=`. Add suggestion and emit the error. + err.span_suggestion_short( + colon_sp, + "use `=` if you meant to assign", + "=".to_string(), + Applicability::MachineApplicable + ); + err.emit(); + // As this was parsed successfully, continue as if the code has been fixed for the + // rest of the file. It will still fail due to the emitted error, but we avoid + // extra noise. + init + } + (Err(mut init_err), Some((snapshot, _, ty_err))) => { // init error, ty error + init_err.cancel(); + // Couldn't parse the type nor the initializer, only raise the type error and + // return to the parser state before parsing the type as the initializer. + // let x: <parse_error>; + mem::replace(self, snapshot); + return Err(ty_err); + } + (Err(err), None) => { // init error, ty parsed + // Couldn't parse the initializer and we're not attempting to recover a failed + // parse of the type, return the error. + return Err(err); + } + }; + let hi = if self.token == token::Semi { + self.span + } else { + self.prev_span + }; + Ok(P(ast::Local { + ty, + pat, + init, + id: ast::DUMMY_NODE_ID, + span: lo.to(hi), + attrs, + })) + } + + /// Parses a structure field. + fn parse_name_and_ty(&mut self, + lo: Span, + vis: Visibility, + attrs: Vec<Attribute>) + -> PResult<'a, StructField> { + let name = self.parse_ident()?; + self.expect(&token::Colon)?; + let ty = self.parse_ty()?; + Ok(StructField { + span: lo.to(self.prev_span), + ident: Some(name), + vis, + id: ast::DUMMY_NODE_ID, + ty, + attrs, + }) + } + + /// Emits an expected-item-after-attributes error. + fn expected_item_err(&mut self, attrs: &[Attribute]) -> PResult<'a, ()> { + let message = match attrs.last() { + Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment", + _ => "expected item after attributes", + }; + + let mut err = self.diagnostic().struct_span_err(self.prev_span, message); + if attrs.last().unwrap().is_sugared_doc { + err.span_label(self.prev_span, "this doc comment doesn't document anything"); + } + Err(err) + } + + /// Parse a statement. This stops just before trailing semicolons on everything but items. + /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed. + pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> { + Ok(self.parse_stmt_(true)) + } + + // Eat tokens until we can be relatively sure we reached the end of the + // statement. This is something of a best-effort heuristic. + // + // We terminate when we find an unmatched `}` (without consuming it). + fn recover_stmt(&mut self) { + self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore) + } + + // If `break_on_semi` is `Break`, then we will stop consuming tokens after + // finding (and consuming) a `;` outside of `{}` or `[]` (note that this is + // approximate - it can mean we break too early due to macros, but that + // should only lead to sub-optimal recovery, not inaccurate parsing). + // + // If `break_on_block` is `Break`, then we will stop consuming tokens + // after finding (and consuming) a brace-delimited block. + fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) { + let mut brace_depth = 0; + let mut bracket_depth = 0; + let mut in_block = false; + debug!("recover_stmt_ enter loop (semi={:?}, block={:?})", + break_on_semi, break_on_block); + loop { + debug!("recover_stmt_ loop {:?}", self.token); + match self.token { + token::OpenDelim(token::DelimToken::Brace) => { + brace_depth += 1; + self.bump(); + if break_on_block == BlockMode::Break && + brace_depth == 1 && + bracket_depth == 0 { + in_block = true; + } + } + token::OpenDelim(token::DelimToken::Bracket) => { + bracket_depth += 1; + self.bump(); + } + token::CloseDelim(token::DelimToken::Brace) => { + if brace_depth == 0 { + debug!("recover_stmt_ return - close delim {:?}", self.token); + break; + } + brace_depth -= 1; + self.bump(); + if in_block && bracket_depth == 0 && brace_depth == 0 { + debug!("recover_stmt_ return - block end {:?}", self.token); + break; + } + } + token::CloseDelim(token::DelimToken::Bracket) => { + bracket_depth -= 1; + if bracket_depth < 0 { + bracket_depth = 0; + } + self.bump(); + } + token::Eof => { + debug!("recover_stmt_ return - Eof"); + break; + } + token::Semi => { + self.bump(); + if break_on_semi == SemiColonMode::Break && + brace_depth == 0 && + bracket_depth == 0 { + debug!("recover_stmt_ return - Semi"); + break; + } + } + token::Comma => { + if break_on_semi == SemiColonMode::Comma && + brace_depth == 0 && + bracket_depth == 0 { + debug!("recover_stmt_ return - Semi"); + break; + } else { + self.bump(); + } + } + _ => { + self.bump() + } + } + } + } + + fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> { + self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| { + e.emit(); + self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore); + None + }) + } + + fn is_async_block(&mut self) -> bool { + self.token.is_keyword(keywords::Async) && + ( + ( // `async move {` + self.look_ahead(1, |t| t.is_keyword(keywords::Move)) && + self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) + ) || ( // `async {` + self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) + ) + ) + } + + fn is_do_catch_block(&mut self) -> bool { + self.token.is_keyword(keywords::Do) && + self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) && + self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) && + !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL) + } + + fn is_try_block(&mut self) -> bool { + self.token.is_keyword(keywords::Try) && + self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) && + self.span.rust_2018() && + // prevent `while try {} {}`, `if try {} {} else {}`, etc. + !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL) + } + + fn is_union_item(&self) -> bool { + self.token.is_keyword(keywords::Union) && + self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident()) + } + + fn is_crate_vis(&self) -> bool { + self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep) + } + + fn is_existential_type_decl(&self) -> bool { + self.token.is_keyword(keywords::Existential) && + self.look_ahead(1, |t| t.is_keyword(keywords::Type)) + } + + fn is_auto_trait_item(&mut self) -> bool { + // auto trait + (self.token.is_keyword(keywords::Auto) + && self.look_ahead(1, |t| t.is_keyword(keywords::Trait))) + || // unsafe auto trait + (self.token.is_keyword(keywords::Unsafe) && + self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) && + self.look_ahead(2, |t| t.is_keyword(keywords::Trait))) + } + + fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span) + -> PResult<'a, Option<P<Item>>> { + let token_lo = self.span; + let (ident, def) = match self.token { + token::Ident(ident, false) if ident.name == keywords::Macro.name() => { + self.bump(); + let ident = self.parse_ident()?; + let tokens = if self.check(&token::OpenDelim(token::Brace)) { + match self.parse_token_tree() { + TokenTree::Delimited(_, _, tts) => tts, + _ => unreachable!(), + } + } else if self.check(&token::OpenDelim(token::Paren)) { + let args = self.parse_token_tree(); + let body = if self.check(&token::OpenDelim(token::Brace)) { + self.parse_token_tree() + } else { + self.unexpected()?; + unreachable!() + }; + TokenStream::new(vec![ + args.into(), + TokenTree::Token(token_lo.to(self.prev_span), token::FatArrow).into(), + body.into(), + ]) + } else { + self.unexpected()?; + unreachable!() + }; + + (ident, ast::MacroDef { tokens: tokens.into(), legacy: false }) + } + token::Ident(ident, _) if ident.name == "macro_rules" && + self.look_ahead(1, |t| *t == token::Not) => { + let prev_span = self.prev_span; + self.complain_if_pub_macro(&vis.node, prev_span); + self.bump(); + self.bump(); + + let ident = self.parse_ident()?; + let (delim, tokens) = self.expect_delimited_token_tree()?; + if delim != MacDelimiter::Brace { + if !self.eat(&token::Semi) { + let msg = "macros that expand to items must either \ + be surrounded with braces or followed by a semicolon"; + self.span_err(self.prev_span, msg); + } + } + + (ident, ast::MacroDef { tokens: tokens, legacy: true }) + } + _ => return Ok(None), + }; + + let span = lo.to(self.prev_span); + Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec()))) + } + + fn parse_stmt_without_recovery(&mut self, + macro_legacy_warnings: bool) + -> PResult<'a, Option<Stmt>> { + maybe_whole!(self, NtStmt, |x| Some(x)); + + let attrs = self.parse_outer_attributes()?; + let lo = self.span; + + Ok(Some(if self.eat_keyword(keywords::Let) { + Stmt { + id: ast::DUMMY_NODE_ID, + node: StmtKind::Local(self.parse_local(attrs.into())?), + span: lo.to(self.prev_span), + } + } else if let Some(macro_def) = self.eat_macro_def( + &attrs, + &source_map::respan(lo, VisibilityKind::Inherited), + lo, + )? { + Stmt { + id: ast::DUMMY_NODE_ID, + node: StmtKind::Item(macro_def), + span: lo.to(self.prev_span), + } + // Starts like a simple path, being careful to avoid contextual keywords + // such as a union items, item with `crate` visibility or auto trait items. + // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts + // like a path (1 token), but it fact not a path. + // `union::b::c` - path, `union U { ... }` - not a path. + // `crate::b::c` - path, `crate struct S;` - not a path. + } else if self.token.is_path_start() && + !self.token.is_qpath_start() && + !self.is_union_item() && + !self.is_crate_vis() && + !self.is_existential_type_decl() && + !self.is_auto_trait_item() { + let pth = self.parse_path(PathStyle::Expr)?; + + if !self.eat(&token::Not) { + let expr = if self.check(&token::OpenDelim(token::Brace)) { + self.parse_struct_expr(lo, pth, ThinVec::new())? + } else { + let hi = self.prev_span; + self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), ThinVec::new()) + }; + + let expr = self.with_res(Restrictions::STMT_EXPR, |this| { + let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?; + this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr)) + })?; + + return Ok(Some(Stmt { + id: ast::DUMMY_NODE_ID, + node: StmtKind::Expr(expr), + span: lo.to(self.prev_span), + })); + } + + // it's a macro invocation + let id = match self.token { + token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier + _ => self.parse_ident()?, + }; + + // check that we're pointing at delimiters (need to check + // again after the `if`, because of `parse_ident` + // consuming more tokens). + match self.token { + token::OpenDelim(_) => {} + _ => { + // we only expect an ident if we didn't parse one + // above. + let ident_str = if id.name == keywords::Invalid.name() { + "identifier, " + } else { + "" + }; + let tok_str = self.this_token_descr(); + let mut err = self.fatal(&format!("expected {}`(` or `{{`, found {}", + ident_str, + tok_str)); + err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str)); + return Err(err) + }, + } + + let (delim, tts) = self.expect_delimited_token_tree()?; + let hi = self.prev_span; + + let style = if delim == MacDelimiter::Brace { + MacStmtStyle::Braces + } else { + MacStmtStyle::NoBraces + }; + + if id.name == keywords::Invalid.name() { + let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim }); + let node = if delim == MacDelimiter::Brace || + self.token == token::Semi || self.token == token::Eof { + StmtKind::Mac(P((mac, style, attrs.into()))) + } + // We used to incorrectly stop parsing macro-expanded statements here. + // If the next token will be an error anyway but could have parsed with the + // earlier behavior, stop parsing here and emit a warning to avoid breakage. + else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token { + // These can continue an expression, so we can't stop parsing and warn. + token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) | + token::BinOp(token::Minus) | token::BinOp(token::Star) | + token::BinOp(token::And) | token::BinOp(token::Or) | + token::AndAnd | token::OrOr | + token::DotDot | token::DotDotDot | token::DotDotEq => false, + _ => true, + } { + self.warn_missing_semicolon(); + StmtKind::Mac(P((mac, style, attrs.into()))) + } else { + let e = self.mk_mac_expr(lo.to(hi), mac.node, ThinVec::new()); + let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?; + let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?; + StmtKind::Expr(e) + }; + Stmt { + id: ast::DUMMY_NODE_ID, + span: lo.to(hi), + node, + } + } else { + // if it has a special ident, it's definitely an item + // + // Require a semicolon or braces. + if style != MacStmtStyle::Braces { + if !self.eat(&token::Semi) { + self.span_err(self.prev_span, + "macros that expand to items must \ + either be surrounded with braces or \ + followed by a semicolon"); + } + } + let span = lo.to(hi); + Stmt { + id: ast::DUMMY_NODE_ID, + span, + node: StmtKind::Item({ + self.mk_item( + span, id /*id is good here*/, + ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })), + respan(lo, VisibilityKind::Inherited), + attrs) + }), + } + } + } else { + // FIXME: Bad copy of attrs + let old_directory_ownership = + mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock); + let item = self.parse_item_(attrs.clone(), false, true)?; + self.directory.ownership = old_directory_ownership; + + match item { + Some(i) => Stmt { + id: ast::DUMMY_NODE_ID, + span: lo.to(i.span), + node: StmtKind::Item(i), + }, + None => { + let unused_attrs = |attrs: &[Attribute], s: &mut Self| { + if !attrs.is_empty() { + if s.prev_token_kind == PrevTokenKind::DocComment { + s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit(); + } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) { + s.span_err(s.span, "expected statement after outer attribute"); + } + } + }; + + // Do not attempt to parse an expression if we're done here. + if self.token == token::Semi { + unused_attrs(&attrs, self); + self.bump(); + return Ok(None); + } + + if self.token == token::CloseDelim(token::Brace) { + unused_attrs(&attrs, self); + return Ok(None); + } + + // Remainder are line-expr stmts. + let e = self.parse_expr_res( + Restrictions::STMT_EXPR, Some(attrs.into()))?; + Stmt { + id: ast::DUMMY_NODE_ID, + span: lo.to(e.span), + node: StmtKind::Expr(e), + } + } + } + })) + } + + /// Checks if this expression is a successfully parsed statement. + fn expr_is_complete(&mut self, e: &Expr) -> bool { + self.restrictions.contains(Restrictions::STMT_EXPR) && + !classify::expr_requires_semi_to_be_stmt(e) + } + + /// Parses a block. No inner attributes are allowed. + pub fn parse_block(&mut self) -> PResult<'a, P<Block>> { + maybe_whole!(self, NtBlock, |x| x); + + let lo = self.span; + + if !self.eat(&token::OpenDelim(token::Brace)) { + let sp = self.span; + let tok = self.this_token_descr(); + let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok)); + let do_not_suggest_help = + self.token.is_keyword(keywords::In) || self.token == token::Colon; + + if self.token.is_ident_named("and") { + e.span_suggestion_short( + self.span, + "use `&&` instead of `and` for the boolean operator", + "&&".to_string(), + Applicability::MaybeIncorrect, + ); + } + if self.token.is_ident_named("or") { + e.span_suggestion_short( + self.span, + "use `||` instead of `or` for the boolean operator", + "||".to_string(), + Applicability::MaybeIncorrect, + ); + } + + // Check to see if the user has written something like + // + // if (cond) + // bar; + // + // Which is valid in other languages, but not Rust. + match self.parse_stmt_without_recovery(false) { + Ok(Some(stmt)) => { + if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace)) + || do_not_suggest_help { + // if the next token is an open brace (e.g., `if a b {`), the place- + // inside-a-block suggestion would be more likely wrong than right + e.span_label(sp, "expected `{`"); + return Err(e); + } + let mut stmt_span = stmt.span; + // expand the span to include the semicolon, if it exists + if self.eat(&token::Semi) { + stmt_span = stmt_span.with_hi(self.prev_span.hi()); + } + let sugg = pprust::to_string(|s| { + use crate::print::pprust::{PrintState, INDENT_UNIT}; + s.ibox(INDENT_UNIT)?; + s.bopen()?; + s.print_stmt(&stmt)?; + s.bclose_maybe_open(stmt.span, INDENT_UNIT, false) + }); + e.span_suggestion( + stmt_span, + "try placing this code inside a block", + sugg, + // speculative, has been misleading in the past (closed Issue #46836) + Applicability::MaybeIncorrect + ); + } + Err(mut e) => { + self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore); + self.cancel(&mut e); + } + _ => () + } + e.span_label(sp, "expected `{`"); + return Err(e); + } + + self.parse_block_tail(lo, BlockCheckMode::Default) + } + + /// Parses a block. Inner attributes are allowed. + fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> { + maybe_whole!(self, NtBlock, |x| (Vec::new(), x)); + + let lo = self.span; + self.expect(&token::OpenDelim(token::Brace))?; + Ok((self.parse_inner_attributes()?, + self.parse_block_tail(lo, BlockCheckMode::Default)?)) + } + + /// Parses the rest of a block expression or function body. + /// Precondition: already parsed the '{'. + fn parse_block_tail(&mut self, lo: Span, s: BlockCheckMode) -> PResult<'a, P<Block>> { + let mut stmts = vec![]; + while !self.eat(&token::CloseDelim(token::Brace)) { + let stmt = match self.parse_full_stmt(false) { + Err(mut err) => { + err.emit(); + self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore); + Some(Stmt { + id: ast::DUMMY_NODE_ID, + node: StmtKind::Expr(DummyResult::raw_expr(self.span, true)), + span: self.span, + }) + } + Ok(stmt) => stmt, + }; + if let Some(stmt) = stmt { + stmts.push(stmt); + } else if self.token == token::Eof { + break; + } else { + // Found only `;` or `}`. + continue; + }; + } + Ok(P(ast::Block { + stmts, + id: ast::DUMMY_NODE_ID, + rules: s, + span: lo.to(self.prev_span), + })) + } + + /// Parses a statement, including the trailing semicolon. + crate fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> { + // skip looking for a trailing semicolon when we have an interpolated statement + maybe_whole!(self, NtStmt, |x| Some(x)); + + let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? { + Some(stmt) => stmt, + None => return Ok(None), + }; + + match stmt.node { + StmtKind::Expr(ref expr) if self.token != token::Eof => { + // expression without semicolon + if classify::expr_requires_semi_to_be_stmt(expr) { + // Just check for errors and recover; do not eat semicolon yet. + if let Err(mut e) = + self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)]) + { + e.emit(); + self.recover_stmt(); + } + } + } + StmtKind::Local(..) => { + // We used to incorrectly allow a macro-expanded let statement to lack a semicolon. + if macro_legacy_warnings && self.token != token::Semi { + self.warn_missing_semicolon(); + } else { + self.expect_one_of(&[], &[token::Semi])?; + } + } + _ => {} + } + + if self.eat(&token::Semi) { + stmt = stmt.add_trailing_semicolon(); + } + + stmt.span = stmt.span.with_hi(self.prev_span.hi()); + Ok(Some(stmt)) + } + + fn warn_missing_semicolon(&self) { + self.diagnostic().struct_span_warn(self.span, { + &format!("expected `;`, found {}", self.this_token_descr()) + }).note({ + "This was erroneously allowed and will become a hard error in a future release" + }).emit(); + } + + fn err_dotdotdot_syntax(&self, span: Span) { + self.diagnostic().struct_span_err(span, { + "unexpected token: `...`" + }).span_suggestion( + span, "use `..` for an exclusive range", "..".to_owned(), + Applicability::MaybeIncorrect + ).span_suggestion( + span, "or `..=` for an inclusive range", "..=".to_owned(), + Applicability::MaybeIncorrect + ).emit(); + } + + /// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`. + /// + /// ``` + /// BOUND = TY_BOUND | LT_BOUND + /// LT_BOUND = LIFETIME (e.g., `'a`) + /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN) + /// TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`) + /// ``` + fn parse_generic_bounds_common(&mut self, + allow_plus: bool, + colon_span: Option<Span>) -> PResult<'a, GenericBounds> { + let mut bounds = Vec::new(); + let mut negative_bounds = Vec::new(); + let mut last_plus_span = None; + loop { + // This needs to be synchronized with `Token::can_begin_bound`. + let is_bound_start = self.check_path() || self.check_lifetime() || + self.check(&token::Not) || // used for error reporting only + self.check(&token::Question) || + self.check_keyword(keywords::For) || + self.check(&token::OpenDelim(token::Paren)); + if is_bound_start { + let lo = self.span; + let has_parens = self.eat(&token::OpenDelim(token::Paren)); + let inner_lo = self.span; + let is_negative = self.eat(&token::Not); + let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None }; + if self.token.is_lifetime() { + if let Some(question_span) = question { + self.span_err(question_span, + "`?` may only modify trait bounds, not lifetime bounds"); + } + bounds.push(GenericBound::Outlives(self.expect_lifetime())); + if has_parens { + let inner_span = inner_lo.to(self.prev_span); + self.expect(&token::CloseDelim(token::Paren))?; + let mut err = self.struct_span_err( + lo.to(self.prev_span), + "parenthesized lifetime bounds are not supported" + ); + if let Ok(snippet) = self.sess.source_map().span_to_snippet(inner_span) { + err.span_suggestion_short( + lo.to(self.prev_span), + "remove the parentheses", + snippet.to_owned(), + Applicability::MachineApplicable + ); + } + err.emit(); + } + } else { + let lifetime_defs = self.parse_late_bound_lifetime_defs()?; + let path = self.parse_path(PathStyle::Type)?; + if has_parens { + self.expect(&token::CloseDelim(token::Paren))?; + } + let poly_span = lo.to(self.prev_span); + if is_negative { + negative_bounds.push( + last_plus_span.or(colon_span).unwrap() + .to(poly_span)); + } else { + let poly_trait = PolyTraitRef::new(lifetime_defs, path, poly_span); + let modifier = if question.is_some() { + TraitBoundModifier::Maybe + } else { + TraitBoundModifier::None + }; + bounds.push(GenericBound::Trait(poly_trait, modifier)); + } + } + } else { + break + } + + if !allow_plus || !self.eat_plus() { + break + } else { + last_plus_span = Some(self.prev_span); + } + } + + if !negative_bounds.is_empty() { + let plural = negative_bounds.len() > 1; + let mut err = self.struct_span_err(negative_bounds, + "negative trait bounds are not supported"); + let bound_list = colon_span.unwrap().to(self.prev_span); + let mut new_bound_list = String::new(); + if !bounds.is_empty() { + let mut snippets = bounds.iter().map(|bound| bound.span()) + .map(|span| self.sess.source_map().span_to_snippet(span)); + while let Some(Ok(snippet)) = snippets.next() { + new_bound_list.push_str(" + "); + new_bound_list.push_str(&snippet); + } + new_bound_list = new_bound_list.replacen(" +", ":", 1); + } + err.span_suggestion_short(bound_list, + &format!("remove the trait bound{}", + if plural { "s" } else { "" }), + new_bound_list, + Applicability::MachineApplicable); + err.emit(); + } + + return Ok(bounds); + } + + fn parse_generic_bounds(&mut self, colon_span: Option<Span>) -> PResult<'a, GenericBounds> { + self.parse_generic_bounds_common(true, colon_span) + } + + /// Parses bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`. + /// + /// ``` + /// BOUND = LT_BOUND (e.g., `'a`) + /// ``` + fn parse_lt_param_bounds(&mut self) -> GenericBounds { + let mut lifetimes = Vec::new(); + while self.check_lifetime() { + lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime())); + + if !self.eat_plus() { + break + } + } + lifetimes + } + + /// Matches `typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?`. + fn parse_ty_param(&mut self, + preceding_attrs: Vec<Attribute>) + -> PResult<'a, GenericParam> { + let ident = self.parse_ident()?; + + // Parse optional colon and param bounds. + let bounds = if self.eat(&token::Colon) { + self.parse_generic_bounds(None)? + } else { + Vec::new() + }; + + let default = if self.eat(&token::Eq) { + Some(self.parse_ty()?) + } else { + None + }; + + Ok(GenericParam { + ident, + id: ast::DUMMY_NODE_ID, + attrs: preceding_attrs.into(), + bounds, + kind: GenericParamKind::Type { + default, + } + }) + } + + /// Parses the following grammar: + /// + /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty] + fn parse_trait_item_assoc_ty(&mut self) + -> PResult<'a, (Ident, TraitItemKind, ast::Generics)> { + let ident = self.parse_ident()?; + let mut generics = self.parse_generics()?; + + // Parse optional colon and param bounds. + let bounds = if self.eat(&token::Colon) { + self.parse_generic_bounds(None)? + } else { + Vec::new() + }; + generics.where_clause = self.parse_where_clause()?; + + let default = if self.eat(&token::Eq) { + Some(self.parse_ty()?) + } else { + None + }; + self.expect(&token::Semi)?; + + Ok((ident, TraitItemKind::Type(bounds, default), generics)) + } + + fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> { + self.expect_keyword(keywords::Const)?; + let ident = self.parse_ident()?; + self.expect(&token::Colon)?; + let ty = self.parse_ty()?; + + Ok(GenericParam { + ident, + id: ast::DUMMY_NODE_ID, + attrs: preceding_attrs.into(), + bounds: Vec::new(), + kind: GenericParamKind::Const { + ty, + } + }) + } + + /// Parses a (possibly empty) list of lifetime and type parameters, possibly including + /// a trailing comma and erroneous trailing attributes. + crate fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> { + let mut params = Vec::new(); + loop { + let attrs = self.parse_outer_attributes()?; + if self.check_lifetime() { + let lifetime = self.expect_lifetime(); + // Parse lifetime parameter. + let bounds = if self.eat(&token::Colon) { + self.parse_lt_param_bounds() + } else { + Vec::new() + }; + params.push(ast::GenericParam { + ident: lifetime.ident, + id: lifetime.id, + attrs: attrs.into(), + bounds, + kind: ast::GenericParamKind::Lifetime, + }); + } else if self.check_keyword(keywords::Const) { + // Parse const parameter. + params.push(self.parse_const_param(attrs)?); + } else if self.check_ident() { + // Parse type parameter. + params.push(self.parse_ty_param(attrs)?); + } else { + // Check for trailing attributes and stop parsing. + if !attrs.is_empty() { + if !params.is_empty() { + self.struct_span_err( + attrs[0].span, + &format!("trailing attribute after generic parameter"), + ) + .span_label(attrs[0].span, "attributes must go before parameters") + .emit(); + } else { + self.struct_span_err( + attrs[0].span, + &format!("attribute without generic parameters"), + ) + .span_label( + attrs[0].span, + "attributes are only permitted when preceding parameters", + ) + .emit(); + } + } + break + } + + if !self.eat(&token::Comma) { + break + } + } + Ok(params) + } + + /// Parses a set of optional generic type parameter declarations. Where + /// clauses are not parsed here, and must be added later via + /// `parse_where_clause()`. + /// + /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > ) + /// | ( < lifetimes , typaramseq ( , )? > ) + /// where typaramseq = ( typaram ) | ( typaram , typaramseq ) + fn parse_generics(&mut self) -> PResult<'a, ast::Generics> { + maybe_whole!(self, NtGenerics, |x| x); + + let span_lo = self.span; + if self.eat_lt() { + let params = self.parse_generic_params()?; + self.expect_gt()?; + Ok(ast::Generics { + params, + where_clause: WhereClause { + id: ast::DUMMY_NODE_ID, + predicates: Vec::new(), + span: syntax_pos::DUMMY_SP, + }, + span: span_lo.to(self.prev_span), + }) + } else { + Ok(ast::Generics::default()) + } + } + + /// Parses generic args (within a path segment) with recovery for extra leading angle brackets. + /// For the purposes of understanding the parsing logic of generic arguments, this function + /// can be thought of being the same as just calling `self.parse_generic_args()` if the source + /// had the correct amount of leading angle brackets. + /// + /// ```ignore (diagnostics) + /// bar::<<<<T as Foo>::Output>(); + /// ^^ help: remove extra angle brackets + /// ``` + fn parse_generic_args_with_leaning_angle_bracket_recovery( + &mut self, + style: PathStyle, + lo: Span, + ) -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> { + // We need to detect whether there are extra leading left angle brackets and produce an + // appropriate error and suggestion. This cannot be implemented by looking ahead at + // upcoming tokens for a matching `>` character - if there are unmatched `<` tokens + // then there won't be matching `>` tokens to find. + // + // To explain how this detection works, consider the following example: + // + // ```ignore (diagnostics) + // bar::<<<<T as Foo>::Output>(); + // ^^ help: remove extra angle brackets + // ``` + // + // Parsing of the left angle brackets starts in this function. We start by parsing the + // `<` token (incrementing the counter of unmatched angle brackets on `Parser` via + // `eat_lt`): + // + // *Upcoming tokens:* `<<<<T as Foo>::Output>;` + // *Unmatched count:* 1 + // *`parse_path_segment` calls deep:* 0 + // + // This has the effect of recursing as this function is called if a `<` character + // is found within the expected generic arguments: + // + // *Upcoming tokens:* `<<<T as Foo>::Output>;` + // *Unmatched count:* 2 + // *`parse_path_segment` calls deep:* 1 + // + // Eventually we will have recursed until having consumed all of the `<` tokens and + // this will be reflected in the count: + // + // *Upcoming tokens:* `T as Foo>::Output>;` + // *Unmatched count:* 4 + // `parse_path_segment` calls deep:* 3 + // + // The parser will continue until reaching the first `>` - this will decrement the + // unmatched angle bracket count and return to the parent invocation of this function + // having succeeded in parsing: + // + // *Upcoming tokens:* `::Output>;` + // *Unmatched count:* 3 + // *`parse_path_segment` calls deep:* 2 + // + // This will continue until the next `>` character which will also return successfully + // to the parent invocation of this function and decrement the count: + // + // *Upcoming tokens:* `;` + // *Unmatched count:* 2 + // *`parse_path_segment` calls deep:* 1 + // + // At this point, this function will expect to find another matching `>` character but + // won't be able to and will return an error. This will continue all the way up the + // call stack until the first invocation: + // + // *Upcoming tokens:* `;` + // *Unmatched count:* 2 + // *`parse_path_segment` calls deep:* 0 + // + // In doing this, we have managed to work out how many unmatched leading left angle + // brackets there are, but we cannot recover as the unmatched angle brackets have + // already been consumed. To remedy this, we keep a snapshot of the parser state + // before we do the above. We can then inspect whether we ended up with a parsing error + // and unmatched left angle brackets and if so, restore the parser state before we + // consumed any `<` characters to emit an error and consume the erroneous tokens to + // recover by attempting to parse again. + // + // In practice, the recursion of this function is indirect and there will be other + // locations that consume some `<` characters - as long as we update the count when + // this happens, it isn't an issue. + + let is_first_invocation = style == PathStyle::Expr; + // Take a snapshot before attempting to parse - we can restore this later. + let snapshot = if is_first_invocation { + Some(self.clone()) + } else { + None + }; + + debug!("parse_generic_args_with_leading_angle_bracket_recovery: (snapshotting)"); + match self.parse_generic_args() { + Ok(value) => Ok(value), + Err(ref mut e) if is_first_invocation && self.unmatched_angle_bracket_count > 0 => { + // Cancel error from being unable to find `>`. We know the error + // must have been this due to a non-zero unmatched angle bracket + // count. + e.cancel(); + + // Swap `self` with our backup of the parser state before attempting to parse + // generic arguments. + let snapshot = mem::replace(self, snapshot.unwrap()); + + debug!( + "parse_generic_args_with_leading_angle_bracket_recovery: (snapshot failure) \ + snapshot.count={:?}", + snapshot.unmatched_angle_bracket_count, + ); + + // Eat the unmatched angle brackets. + for _ in 0..snapshot.unmatched_angle_bracket_count { + self.eat_lt(); + } + + // Make a span over ${unmatched angle bracket count} characters. + let span = lo.with_hi( + lo.lo() + BytePos(snapshot.unmatched_angle_bracket_count) + ); + let plural = snapshot.unmatched_angle_bracket_count > 1; + self.diagnostic() + .struct_span_err( + span, + &format!( + "unmatched angle bracket{}", + if plural { "s" } else { "" } + ), + ) + .span_suggestion( + span, + &format!( + "remove extra angle bracket{}", + if plural { "s" } else { "" } + ), + String::new(), + Applicability::MachineApplicable, + ) + .emit(); + + // Try again without unmatched angle bracket characters. + self.parse_generic_args() + }, + Err(e) => Err(e), + } + } + + /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings, + /// possibly including trailing comma. + fn parse_generic_args(&mut self) -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> { + let mut args = Vec::new(); + let mut bindings = Vec::new(); + let mut misplaced_assoc_ty_bindings: Vec<Span> = Vec::new(); + let mut assoc_ty_bindings: Vec<Span> = Vec::new(); + + let args_lo = self.span; + + loop { + if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) { + // Parse lifetime argument. + args.push(GenericArg::Lifetime(self.expect_lifetime())); + misplaced_assoc_ty_bindings.append(&mut assoc_ty_bindings); + } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) { + // Parse associated type binding. + let lo = self.span; + let ident = self.parse_ident()?; + self.bump(); + let ty = self.parse_ty()?; + let span = lo.to(self.prev_span); + bindings.push(TypeBinding { + id: ast::DUMMY_NODE_ID, + ident, + ty, + span, + }); + assoc_ty_bindings.push(span); + } else if self.check_const_arg() { + // FIXME(const_generics): to distinguish between idents for types and consts, + // we should introduce a GenericArg::Ident in the AST and distinguish when + // lowering to the HIR. For now, idents for const args are not permitted. + + // Parse const argument. + let expr = if let token::OpenDelim(token::Brace) = self.token { + self.parse_block_expr(None, self.span, BlockCheckMode::Default, ThinVec::new())? + } else if self.token.is_ident() { + // FIXME(const_generics): to distinguish between idents for types and consts, + // we should introduce a GenericArg::Ident in the AST and distinguish when + // lowering to the HIR. For now, idents for const args are not permitted. + return Err( + self.fatal("identifiers may currently not be used for const generics") + ); + } else { + // FIXME(const_generics): this currently conflicts with emplacement syntax + // with negative integer literals. + self.parse_literal_maybe_minus()? + }; + let value = AnonConst { + id: ast::DUMMY_NODE_ID, + value: expr, + }; + args.push(GenericArg::Const(value)); + misplaced_assoc_ty_bindings.append(&mut assoc_ty_bindings); + } else if self.check_type() { + // Parse type argument. + args.push(GenericArg::Type(self.parse_ty()?)); + misplaced_assoc_ty_bindings.append(&mut assoc_ty_bindings); + } else { + break + } + + if !self.eat(&token::Comma) { + break + } + } + + // FIXME: we would like to report this in ast_validation instead, but we currently do not + // preserve ordering of generic parameters with respect to associated type binding, so we + // lose that information after parsing. + if misplaced_assoc_ty_bindings.len() > 0 { + let mut err = self.struct_span_err( + args_lo.to(self.prev_span), + "associated type bindings must be declared after generic parameters", + ); + for span in misplaced_assoc_ty_bindings { + err.span_label( + span, + "this associated type binding should be moved after the generic parameters", + ); + } + err.emit(); + } + + Ok((args, bindings)) + } + + /// Parses an optional where-clause and places it in `generics`. + /// + /// ```ignore (only-for-syntax-highlight) + /// where T : Trait<U, V> + 'b, 'a : 'b + /// ``` + fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> { + maybe_whole!(self, NtWhereClause, |x| x); + + let mut where_clause = WhereClause { + id: ast::DUMMY_NODE_ID, + predicates: Vec::new(), + span: syntax_pos::DUMMY_SP, + }; + + if !self.eat_keyword(keywords::Where) { + return Ok(where_clause); + } + let lo = self.prev_span; + + // We are considering adding generics to the `where` keyword as an alternative higher-rank + // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking + // change we parse those generics now, but report an error. + if self.choose_generics_over_qpath() { + let generics = self.parse_generics()?; + self.struct_span_err( + generics.span, + "generic parameters on `where` clauses are reserved for future use", + ) + .span_label(generics.span, "currently unsupported") + .emit(); + } + + loop { + let lo = self.span; + if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) { + let lifetime = self.expect_lifetime(); + // Bounds starting with a colon are mandatory, but possibly empty. + self.expect(&token::Colon)?; + let bounds = self.parse_lt_param_bounds(); + where_clause.predicates.push(ast::WherePredicate::RegionPredicate( + ast::WhereRegionPredicate { + span: lo.to(self.prev_span), + lifetime, + bounds, + } + )); + } else if self.check_type() { + // Parse optional `for<'a, 'b>`. + // This `for` is parsed greedily and applies to the whole predicate, + // the bounded type can have its own `for` applying only to it. + // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/> + // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/> + // Example 3: for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /*ok*/, 'b /*not ok*/> + let lifetime_defs = self.parse_late_bound_lifetime_defs()?; + + // Parse type with mandatory colon and (possibly empty) bounds, + // or with mandatory equality sign and the second type. + let ty = self.parse_ty()?; + if self.eat(&token::Colon) { + let bounds = self.parse_generic_bounds(None)?; + where_clause.predicates.push(ast::WherePredicate::BoundPredicate( + ast::WhereBoundPredicate { + span: lo.to(self.prev_span), + bound_generic_params: lifetime_defs, + bounded_ty: ty, + bounds, + } + )); + // FIXME: Decide what should be used here, `=` or `==`. + // FIXME: We are just dropping the binders in lifetime_defs on the floor here. + } else if self.eat(&token::Eq) || self.eat(&token::EqEq) { + let rhs_ty = self.parse_ty()?; + where_clause.predicates.push(ast::WherePredicate::EqPredicate( + ast::WhereEqPredicate { + span: lo.to(self.prev_span), + lhs_ty: ty, + rhs_ty, + id: ast::DUMMY_NODE_ID, + } + )); + } else { + return self.unexpected(); + } + } else { + break + } + + if !self.eat(&token::Comma) { + break + } + } + + where_clause.span = lo.to(self.prev_span); + Ok(where_clause) + } + + fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool) + -> PResult<'a, (Vec<Arg> , bool)> { + self.expect(&token::OpenDelim(token::Paren))?; + + let sp = self.span; + let mut variadic = false; + let (args, recovered): (Vec<Option<Arg>>, bool) = + self.parse_seq_to_before_end( + &token::CloseDelim(token::Paren), + SeqSep::trailing_allowed(token::Comma), + |p| { + if p.token == token::DotDotDot { + p.bump(); + variadic = true; + if allow_variadic { + if p.token != token::CloseDelim(token::Paren) { + let span = p.span; + p.span_err(span, + "`...` must be last in argument list for variadic function"); + } + Ok(None) + } else { + let span = p.prev_span; + if p.token == token::CloseDelim(token::Paren) { + // continue parsing to present any further errors + p.struct_span_err( + span, + "only foreign functions are allowed to be variadic" + ).emit(); + Ok(Some(dummy_arg(span))) + } else { + // this function definition looks beyond recovery, stop parsing + p.span_err(span, + "only foreign functions are allowed to be variadic"); + Ok(None) + } + } + } else { + match p.parse_arg_general(named_args, false) { + Ok(arg) => Ok(Some(arg)), + Err(mut e) => { + e.emit(); + let lo = p.prev_span; + // Skip every token until next possible arg or end. + p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]); + // Create a placeholder argument for proper arg count (#34264). + let span = lo.to(p.prev_span); + Ok(Some(dummy_arg(span))) + } + } + } + } + )?; + + if !recovered { + self.eat(&token::CloseDelim(token::Paren)); + } + + let args: Vec<_> = args.into_iter().filter_map(|x| x).collect(); + + if variadic && args.is_empty() { + self.span_err(sp, + "variadic function must be declared with at least one named argument"); + } + + Ok((args, variadic)) + } + + /// Parses the argument list and result type of a function declaration. + fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> { + + let (args, variadic) = self.parse_fn_args(true, allow_variadic)?; + let ret_ty = self.parse_ret_ty(true)?; + + Ok(P(FnDecl { + inputs: args, + output: ret_ty, + variadic, + })) + } + + /// Returns the parsed optional self argument and whether a self shortcut was used. + fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> { + let expect_ident = |this: &mut Self| match this.token { + // Preserve hygienic context. + token::Ident(ident, _) => + { let span = this.span; this.bump(); Ident::new(ident.name, span) } + _ => unreachable!() + }; + let isolated_self = |this: &mut Self, n| { + this.look_ahead(n, |t| t.is_keyword(keywords::SelfLower)) && + this.look_ahead(n + 1, |t| t != &token::ModSep) + }; + + // Parse optional self parameter of a method. + // Only a limited set of initial token sequences is considered self parameters, anything + // else is parsed as a normal function parameter list, so some lookahead is required. + let eself_lo = self.span; + let (eself, eself_ident, eself_hi) = match self.token { + token::BinOp(token::And) => { + // &self + // &mut self + // &'lt self + // &'lt mut self + // ¬_self + (if isolated_self(self, 1) { + self.bump(); + SelfKind::Region(None, Mutability::Immutable) + } else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) && + isolated_self(self, 2) { + self.bump(); + self.bump(); + SelfKind::Region(None, Mutability::Mutable) + } else if self.look_ahead(1, |t| t.is_lifetime()) && + isolated_self(self, 2) { + self.bump(); + let lt = self.expect_lifetime(); + SelfKind::Region(Some(lt), Mutability::Immutable) + } else if self.look_ahead(1, |t| t.is_lifetime()) && + self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) && + isolated_self(self, 3) { + self.bump(); + let lt = self.expect_lifetime(); + self.bump(); + SelfKind::Region(Some(lt), Mutability::Mutable) + } else { + return Ok(None); + }, expect_ident(self), self.prev_span) + } + token::BinOp(token::Star) => { + // *self + // *const self + // *mut self + // *not_self + // Emit special error for `self` cases. + let msg = "cannot pass `self` by raw pointer"; + (if isolated_self(self, 1) { + self.bump(); + self.struct_span_err(self.span, msg) + .span_label(self.span, msg) + .emit(); + SelfKind::Value(Mutability::Immutable) + } else if self.look_ahead(1, |t| t.is_mutability()) && + isolated_self(self, 2) { + self.bump(); + self.bump(); + self.struct_span_err(self.span, msg) + .span_label(self.span, msg) + .emit(); + SelfKind::Value(Mutability::Immutable) + } else { + return Ok(None); + }, expect_ident(self), self.prev_span) + } + token::Ident(..) => { + if isolated_self(self, 0) { + // self + // self: TYPE + let eself_ident = expect_ident(self); + let eself_hi = self.prev_span; + (if self.eat(&token::Colon) { + let ty = self.parse_ty()?; + SelfKind::Explicit(ty, Mutability::Immutable) + } else { + SelfKind::Value(Mutability::Immutable) + }, eself_ident, eself_hi) + } else if self.token.is_keyword(keywords::Mut) && + isolated_self(self, 1) { + // mut self + // mut self: TYPE + self.bump(); + let eself_ident = expect_ident(self); + let eself_hi = self.prev_span; + (if self.eat(&token::Colon) { + let ty = self.parse_ty()?; + SelfKind::Explicit(ty, Mutability::Mutable) + } else { + SelfKind::Value(Mutability::Mutable) + }, eself_ident, eself_hi) + } else { + return Ok(None); + } + } + _ => return Ok(None), + }; + + let eself = source_map::respan(eself_lo.to(eself_hi), eself); + Ok(Some(Arg::from_self(eself, eself_ident))) + } + + /// Parses the parameter list and result type of a function that may have a `self` parameter. + fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>> + where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>, + { + self.expect(&token::OpenDelim(token::Paren))?; + + // Parse optional self argument + let self_arg = self.parse_self_arg()?; + + // Parse the rest of the function parameter list. + let sep = SeqSep::trailing_allowed(token::Comma); + let (fn_inputs, recovered) = if let Some(self_arg) = self_arg { + if self.check(&token::CloseDelim(token::Paren)) { + (vec![self_arg], false) + } else if self.eat(&token::Comma) { + let mut fn_inputs = vec![self_arg]; + let (mut input, recovered) = self.parse_seq_to_before_end( + &token::CloseDelim(token::Paren), sep, parse_arg_fn)?; + fn_inputs.append(&mut input); + (fn_inputs, recovered) + } else { + return self.unexpected(); + } + } else { + self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)? + }; + + if !recovered { + // Parse closing paren and return type. + self.expect(&token::CloseDelim(token::Paren))?; + } + Ok(P(FnDecl { + inputs: fn_inputs, + output: self.parse_ret_ty(true)?, + variadic: false + })) + } + + /// Parses the `|arg, arg|` header of a closure. + fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> { + let inputs_captures = { + if self.eat(&token::OrOr) { + Vec::new() + } else { + self.expect(&token::BinOp(token::Or))?; + let args = self.parse_seq_to_before_tokens( + &[&token::BinOp(token::Or), &token::OrOr], + SeqSep::trailing_allowed(token::Comma), + TokenExpectType::NoExpect, + |p| p.parse_fn_block_arg() + )?.0; + self.expect_or()?; + args + } + }; + let output = self.parse_ret_ty(true)?; + + Ok(P(FnDecl { + inputs: inputs_captures, + output, + variadic: false + })) + } + + /// Parses the name and optional generic types of a function header. + fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> { + let id = self.parse_ident()?; + let generics = self.parse_generics()?; + Ok((id, generics)) + } + + fn mk_item(&mut self, span: Span, ident: Ident, node: ItemKind, vis: Visibility, + attrs: Vec<Attribute>) -> P<Item> { + P(Item { + ident, + attrs, + id: ast::DUMMY_NODE_ID, + node, + vis, + span, + tokens: None, + }) + } + + /// Parses an item-position function declaration. + fn parse_item_fn(&mut self, + unsafety: Unsafety, + asyncness: IsAsync, + constness: Spanned<Constness>, + abi: Abi) + -> PResult<'a, ItemInfo> { + let (ident, mut generics) = self.parse_fn_header()?; + let decl = self.parse_fn_decl(false)?; + generics.where_clause = self.parse_where_clause()?; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + let header = FnHeader { unsafety, asyncness, constness, abi }; + Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs))) + } + + /// Returns `true` if we are looking at `const ID` + /// (returns `false` for things like `const fn`, etc.). + fn is_const_item(&mut self) -> bool { + self.token.is_keyword(keywords::Const) && + !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) && + !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) + } + + /// Parses all the "front matter" for a `fn` declaration, up to + /// and including the `fn` keyword: + /// + /// - `const fn` + /// - `unsafe fn` + /// - `const unsafe fn` + /// - `extern fn` + /// - etc. + fn parse_fn_front_matter(&mut self) + -> PResult<'a, ( + Spanned<Constness>, + Unsafety, + IsAsync, + Abi + )> + { + let is_const_fn = self.eat_keyword(keywords::Const); + let const_span = self.prev_span; + let unsafety = self.parse_unsafety(); + let asyncness = self.parse_asyncness(); + let (constness, unsafety, abi) = if is_const_fn { + (respan(const_span, Constness::Const), unsafety, Abi::Rust) + } else { + let abi = if self.eat_keyword(keywords::Extern) { + self.parse_opt_abi()?.unwrap_or(Abi::C) + } else { + Abi::Rust + }; + (respan(self.prev_span, Constness::NotConst), unsafety, abi) + }; + self.expect_keyword(keywords::Fn)?; + Ok((constness, unsafety, asyncness, abi)) + } + + /// Parses an impl item. + pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> { + maybe_whole!(self, NtImplItem, |x| x); + let attrs = self.parse_outer_attributes()?; + let (mut item, tokens) = self.collect_tokens(|this| { + this.parse_impl_item_(at_end, attrs) + })?; + + // See `parse_item` for why this clause is here. + if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) { + item.tokens = Some(tokens); + } + Ok(item) + } + + fn parse_impl_item_(&mut self, + at_end: &mut bool, + mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> { + let lo = self.span; + let vis = self.parse_visibility(false)?; + let defaultness = self.parse_defaultness(); + let (name, node, generics) = if let Some(type_) = self.eat_type() { + let (name, alias, generics) = type_?; + let kind = match alias { + AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ), + AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds), + }; + (name, kind, generics) + } else if self.is_const_item() { + // This parses the grammar: + // ImplItemConst = "const" Ident ":" Ty "=" Expr ";" + self.expect_keyword(keywords::Const)?; + let name = self.parse_ident()?; + self.expect(&token::Colon)?; + let typ = self.parse_ty()?; + self.expect(&token::Eq)?; + let expr = self.parse_expr()?; + self.expect(&token::Semi)?; + (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default()) + } else { + let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?; + attrs.extend(inner_attrs); + (name, node, generics) + }; + + Ok(ImplItem { + id: ast::DUMMY_NODE_ID, + span: lo.to(self.prev_span), + ident: name, + vis, + defaultness, + attrs, + generics, + node, + tokens: None, + }) + } + + fn complain_if_pub_macro(&mut self, vis: &VisibilityKind, sp: Span) { + match *vis { + VisibilityKind::Inherited => {} + _ => { + let is_macro_rules: bool = match self.token { + token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"), + _ => false, + }; + let mut err = if is_macro_rules { + let mut err = self.diagnostic() + .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`"); + err.span_suggestion( + sp, + "try exporting the macro", + "#[macro_export]".to_owned(), + Applicability::MaybeIncorrect // speculative + ); + err + } else { + let mut err = self.diagnostic() + .struct_span_err(sp, "can't qualify macro invocation with `pub`"); + err.help("try adjusting the macro to put `pub` inside the invocation"); + err + }; + err.emit(); + } + } + } + + fn missing_assoc_item_kind_err(&mut self, item_type: &str, prev_span: Span) + -> DiagnosticBuilder<'a> + { + let expected_kinds = if item_type == "extern" { + "missing `fn`, `type`, or `static`" + } else { + "missing `fn`, `type`, or `const`" + }; + + // Given this code `path(`, it seems like this is not + // setting the visibility of a macro invocation, but rather + // a mistyped method declaration. + // Create a diagnostic pointing out that `fn` is missing. + // + // x | pub path(&self) { + // | ^ missing `fn`, `type`, or `const` + // pub path( + // ^^ `sp` below will point to this + let sp = prev_span.between(self.prev_span); + let mut err = self.diagnostic().struct_span_err( + sp, + &format!("{} for {}-item declaration", + expected_kinds, item_type)); + err.span_label(sp, expected_kinds); + err + } + + /// Parse a method or a macro invocation in a trait impl. + fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool) + -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics, + ast::ImplItemKind)> { + // code copied from parse_macro_use_or_failure... abstraction! + if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? { + // method macro + Ok((keywords::Invalid.ident(), vec![], ast::Generics::default(), + ast::ImplItemKind::Macro(mac))) + } else { + let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?; + let ident = self.parse_ident()?; + let mut generics = self.parse_generics()?; + let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?; + generics.where_clause = self.parse_where_clause()?; + *at_end = true; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + let header = ast::FnHeader { abi, unsafety, constness, asyncness }; + Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method( + ast::MethodSig { header, decl }, + body + ))) + } + } + + /// Parses `trait Foo { ... }` or `trait Foo = Bar;`. + fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> { + let ident = self.parse_ident()?; + let mut tps = self.parse_generics()?; + + // Parse optional colon and supertrait bounds. + let bounds = if self.eat(&token::Colon) { + self.parse_generic_bounds(Some(self.prev_span))? + } else { + Vec::new() + }; + + if self.eat(&token::Eq) { + // it's a trait alias + let bounds = self.parse_generic_bounds(None)?; + tps.where_clause = self.parse_where_clause()?; + self.expect(&token::Semi)?; + if is_auto == IsAuto::Yes { + let msg = "trait aliases cannot be `auto`"; + self.struct_span_err(self.prev_span, msg) + .span_label(self.prev_span, msg) + .emit(); + } + if unsafety != Unsafety::Normal { + let msg = "trait aliases cannot be `unsafe`"; + self.struct_span_err(self.prev_span, msg) + .span_label(self.prev_span, msg) + .emit(); + } + Ok((ident, ItemKind::TraitAlias(tps, bounds), None)) + } else { + // it's a normal trait + tps.where_clause = self.parse_where_clause()?; + self.expect(&token::OpenDelim(token::Brace))?; + let mut trait_items = vec![]; + while !self.eat(&token::CloseDelim(token::Brace)) { + let mut at_end = false; + match self.parse_trait_item(&mut at_end) { + Ok(item) => trait_items.push(item), + Err(mut e) => { + e.emit(); + if !at_end { + self.recover_stmt_(SemiColonMode::Break, BlockMode::Break); + } + } + } + } + Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None)) + } + } + + fn choose_generics_over_qpath(&self) -> bool { + // There's an ambiguity between generic parameters and qualified paths in impls. + // If we see `<` it may start both, so we have to inspect some following tokens. + // The following combinations can only start generics, + // but not qualified paths (with one exception): + // `<` `>` - empty generic parameters + // `<` `#` - generic parameters with attributes + // `<` (LIFETIME|IDENT) `>` - single generic parameter + // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list + // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds + // `<` (LIFETIME|IDENT) `=` - generic parameter with a default + // `<` const - generic const parameter + // The only truly ambiguous case is + // `<` IDENT `>` `::` IDENT ... + // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`) + // because this is what almost always expected in practice, qualified paths in impls + // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment. + self.token == token::Lt && + (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) || + self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) && + self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma || + t == &token::Colon || t == &token::Eq) || + self.look_ahead(1, |t| t.is_keyword(keywords::Const))) + } + + fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> { + self.expect(&token::OpenDelim(token::Brace))?; + let attrs = self.parse_inner_attributes()?; + + let mut impl_items = Vec::new(); + while !self.eat(&token::CloseDelim(token::Brace)) { + let mut at_end = false; + match self.parse_impl_item(&mut at_end) { + Ok(impl_item) => impl_items.push(impl_item), + Err(mut err) => { + err.emit(); + if !at_end { + self.recover_stmt_(SemiColonMode::Break, BlockMode::Break); + } + } + } + } + Ok((impl_items, attrs)) + } + + /// Parses an implementation item, `impl` keyword is already parsed. + /// + /// impl<'a, T> TYPE { /* impl items */ } + /// impl<'a, T> TRAIT for TYPE { /* impl items */ } + /// impl<'a, T> !TRAIT for TYPE { /* impl items */ } + /// + /// We actually parse slightly more relaxed grammar for better error reporting and recovery. + /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}` + /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}` + fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness) + -> PResult<'a, ItemInfo> { + // First, parse generic parameters if necessary. + let mut generics = if self.choose_generics_over_qpath() { + self.parse_generics()? + } else { + ast::Generics::default() + }; + + // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type. + let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) { + self.bump(); // `!` + ast::ImplPolarity::Negative + } else { + ast::ImplPolarity::Positive + }; + + // Parse both types and traits as a type, then reinterpret if necessary. + let ty_first = self.parse_ty()?; + + // If `for` is missing we try to recover. + let has_for = self.eat_keyword(keywords::For); + let missing_for_span = self.prev_span.between(self.span); + + let ty_second = if self.token == token::DotDot { + // We need to report this error after `cfg` expansion for compatibility reasons + self.bump(); // `..`, do not add it to expected tokens + Some(P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID })) + } else if has_for || self.token.can_begin_type() { + Some(self.parse_ty()?) + } else { + None + }; + + generics.where_clause = self.parse_where_clause()?; + + let (impl_items, attrs) = self.parse_impl_body()?; + + let item_kind = match ty_second { + Some(ty_second) => { + // impl Trait for Type + if !has_for { + self.struct_span_err(missing_for_span, "missing `for` in a trait impl") + .span_suggestion_short( + missing_for_span, + "add `for` here", + " for ".to_string(), + Applicability::MachineApplicable, + ).emit(); + } + + let ty_first = ty_first.into_inner(); + let path = match ty_first.node { + // This notably includes paths passed through `ty` macro fragments (#46438). + TyKind::Path(None, path) => path, + _ => { + self.span_err(ty_first.span, "expected a trait, found type"); + ast::Path::from_ident(Ident::new(keywords::Invalid.name(), ty_first.span)) + } + }; + let trait_ref = TraitRef { path, ref_id: ty_first.id }; + + ItemKind::Impl(unsafety, polarity, defaultness, + generics, Some(trait_ref), ty_second, impl_items) + } + None => { + // impl Type + ItemKind::Impl(unsafety, polarity, defaultness, + generics, None, ty_first, impl_items) + } + }; + + Ok((keywords::Invalid.ident(), item_kind, Some(attrs))) + } + + fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> { + if self.eat_keyword(keywords::For) { + self.expect_lt()?; + let params = self.parse_generic_params()?; + self.expect_gt()?; + // We rely on AST validation to rule out invalid cases: There must not be type + // parameters, and the lifetime parameters must not have bounds. + Ok(params) + } else { + Ok(Vec::new()) + } + } + + /// Parses `struct Foo { ... }`. + fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> { + let class_name = self.parse_ident()?; + + let mut generics = self.parse_generics()?; + + // There is a special case worth noting here, as reported in issue #17904. + // If we are parsing a tuple struct it is the case that the where clause + // should follow the field list. Like so: + // + // struct Foo<T>(T) where T: Copy; + // + // If we are parsing a normal record-style struct it is the case + // that the where clause comes before the body, and after the generics. + // So if we look ahead and see a brace or a where-clause we begin + // parsing a record style struct. + // + // Otherwise if we look ahead and see a paren we parse a tuple-style + // struct. + + let vdata = if self.token.is_keyword(keywords::Where) { + generics.where_clause = self.parse_where_clause()?; + if self.eat(&token::Semi) { + // If we see a: `struct Foo<T> where T: Copy;` style decl. + VariantData::Unit(ast::DUMMY_NODE_ID) + } else { + // If we see: `struct Foo<T> where T: Copy { ... }` + VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID) + } + // No `where` so: `struct Foo<T>;` + } else if self.eat(&token::Semi) { + VariantData::Unit(ast::DUMMY_NODE_ID) + // Record-style struct definition + } else if self.token == token::OpenDelim(token::Brace) { + VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID) + // Tuple-style struct definition with optional where-clause. + } else if self.token == token::OpenDelim(token::Paren) { + let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID); + generics.where_clause = self.parse_where_clause()?; + self.expect(&token::Semi)?; + body + } else { + let token_str = self.this_token_descr(); + let mut err = self.fatal(&format!( + "expected `where`, `{{`, `(`, or `;` after struct name, found {}", + token_str + )); + err.span_label(self.span, "expected `where`, `{`, `(`, or `;` after struct name"); + return Err(err); + }; + + Ok((class_name, ItemKind::Struct(vdata, generics), None)) + } + + /// Parses `union Foo { ... }`. + fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> { + let class_name = self.parse_ident()?; + + let mut generics = self.parse_generics()?; + + let vdata = if self.token.is_keyword(keywords::Where) { + generics.where_clause = self.parse_where_clause()?; + VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID) + } else if self.token == token::OpenDelim(token::Brace) { + VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID) + } else { + let token_str = self.this_token_descr(); + let mut err = self.fatal(&format!( + "expected `where` or `{{` after union name, found {}", token_str)); + err.span_label(self.span, "expected `where` or `{` after union name"); + return Err(err); + }; + + Ok((class_name, ItemKind::Union(vdata, generics), None)) + } + + fn consume_block(&mut self, delim: token::DelimToken) { + let mut brace_depth = 0; + loop { + if self.eat(&token::OpenDelim(delim)) { + brace_depth += 1; + } else if self.eat(&token::CloseDelim(delim)) { + if brace_depth == 0 { + return; + } else { + brace_depth -= 1; + continue; + } + } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) { + return; + } else { + self.bump(); + } + } + } + + fn parse_record_struct_body(&mut self) -> PResult<'a, Vec<StructField>> { + let mut fields = Vec::new(); + if self.eat(&token::OpenDelim(token::Brace)) { + while self.token != token::CloseDelim(token::Brace) { + let field = self.parse_struct_decl_field().map_err(|e| { + self.recover_stmt(); + e + }); + match field { + Ok(field) => fields.push(field), + Err(mut err) => { + err.emit(); + } + } + } + self.eat(&token::CloseDelim(token::Brace)); + } else { + let token_str = self.this_token_descr(); + let mut err = self.fatal(&format!( + "expected `where`, or `{{` after struct name, found {}", token_str)); + err.span_label(self.span, "expected `where`, or `{` after struct name"); + return Err(err); + } + + Ok(fields) + } + + fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> { + // This is the case where we find `struct Foo<T>(T) where T: Copy;` + // Unit like structs are handled in parse_item_struct function + let fields = self.parse_unspanned_seq( + &token::OpenDelim(token::Paren), + &token::CloseDelim(token::Paren), + SeqSep::trailing_allowed(token::Comma), + |p| { + let attrs = p.parse_outer_attributes()?; + let lo = p.span; + let vis = p.parse_visibility(true)?; + let ty = p.parse_ty()?; + Ok(StructField { + span: lo.to(ty.span), + vis, + ident: None, + id: ast::DUMMY_NODE_ID, + ty, + attrs, + }) + })?; + + Ok(fields) + } + + /// Parses a structure field declaration. + fn parse_single_struct_field(&mut self, + lo: Span, + vis: Visibility, + attrs: Vec<Attribute> ) + -> PResult<'a, StructField> { + let mut seen_comma: bool = false; + let a_var = self.parse_name_and_ty(lo, vis, attrs)?; + if self.token == token::Comma { + seen_comma = true; + } + match self.token { + token::Comma => { + self.bump(); + } + token::CloseDelim(token::Brace) => {} + token::DocComment(_) => { + let previous_span = self.prev_span; + let mut err = self.span_fatal_err(self.span, Error::UselessDocComment); + self.bump(); // consume the doc comment + let comma_after_doc_seen = self.eat(&token::Comma); + // `seen_comma` is always false, because we are inside doc block + // condition is here to make code more readable + if seen_comma == false && comma_after_doc_seen == true { + seen_comma = true; + } + if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) { + err.emit(); + } else { + if seen_comma == false { + let sp = self.sess.source_map().next_point(previous_span); + err.span_suggestion( + sp, + "missing comma here", + ",".into(), + Applicability::MachineApplicable + ); + } + return Err(err); + } + } + _ => { + let sp = self.sess.source_map().next_point(self.prev_span); + let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}", + self.this_token_descr())); + if self.token.is_ident() { + // This is likely another field; emit the diagnostic and keep going + err.span_suggestion( + sp, + "try adding a comma", + ",".into(), + Applicability::MachineApplicable, + ); + err.emit(); + } else { + return Err(err) + } + } + } + Ok(a_var) + } + + /// Parses an element of a struct declaration. + fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> { + let attrs = self.parse_outer_attributes()?; + let lo = self.span; + let vis = self.parse_visibility(false)?; + self.parse_single_struct_field(lo, vis, attrs) + } + + /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`, + /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`. + /// If the following element can't be a tuple (i.e., it's a function definition), then + /// it's not a tuple struct field), and the contents within the parentheses isn't valid, + /// so emit a proper diagnostic. + pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> { + maybe_whole!(self, NtVis, |x| x); + + self.expected_tokens.push(TokenType::Keyword(keywords::Crate)); + if self.is_crate_vis() { + self.bump(); // `crate` + return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate))); + } + + if !self.eat_keyword(keywords::Pub) { + // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no + // keyword to grab a span from for inherited visibility; an empty span at the + // beginning of the current token would seem to be the "Schelling span". + return Ok(respan(self.span.shrink_to_lo(), VisibilityKind::Inherited)) + } + let lo = self.prev_span; + + if self.check(&token::OpenDelim(token::Paren)) { + // We don't `self.bump()` the `(` yet because this might be a struct definition where + // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`. + // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so + // by the following tokens. + if self.look_ahead(1, |t| t.is_keyword(keywords::Crate)) { + // `pub(crate)` + self.bump(); // `(` + self.bump(); // `crate` + self.expect(&token::CloseDelim(token::Paren))?; // `)` + let vis = respan( + lo.to(self.prev_span), + VisibilityKind::Crate(CrateSugar::PubCrate), + ); + return Ok(vis) + } else if self.look_ahead(1, |t| t.is_keyword(keywords::In)) { + // `pub(in path)` + self.bump(); // `(` + self.bump(); // `in` + let path = self.parse_path(PathStyle::Mod)?; // `path` + self.expect(&token::CloseDelim(token::Paren))?; // `)` + let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted { + path: P(path), + id: ast::DUMMY_NODE_ID, + }); + return Ok(vis) + } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) && + self.look_ahead(1, |t| t.is_keyword(keywords::Super) || + t.is_keyword(keywords::SelfLower)) + { + // `pub(self)` or `pub(super)` + self.bump(); // `(` + let path = self.parse_path(PathStyle::Mod)?; // `super`/`self` + self.expect(&token::CloseDelim(token::Paren))?; // `)` + let vis = respan(lo.to(self.prev_span), VisibilityKind::Restricted { + path: P(path), + id: ast::DUMMY_NODE_ID, + }); + return Ok(vis) + } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct + // `pub(something) fn ...` or `struct X { pub(something) y: Z }` + self.bump(); // `(` + let msg = "incorrect visibility restriction"; + let suggestion = r##"some possible visibility restrictions are: +`pub(crate)`: visible only on the current crate +`pub(super)`: visible only in the current module's parent +`pub(in path::to::module)`: visible only on the specified path"##; + let path = self.parse_path(PathStyle::Mod)?; + let sp = self.prev_span; + let help_msg = format!("make this visible only to module `{}` with `in`", path); + self.expect(&token::CloseDelim(token::Paren))?; // `)` + let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg); + err.help(suggestion); + err.span_suggestion( + sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable + ); + err.emit(); // emit diagnostic, but continue with public visibility + } + } + + Ok(respan(lo, VisibilityKind::Public)) + } + + /// Parses defaultness (i.e., `default` or nothing). + fn parse_defaultness(&mut self) -> Defaultness { + // `pub` is included for better error messages + if self.check_keyword(keywords::Default) && + self.look_ahead(1, |t| t.is_keyword(keywords::Impl) || + t.is_keyword(keywords::Const) || + t.is_keyword(keywords::Fn) || + t.is_keyword(keywords::Unsafe) || + t.is_keyword(keywords::Extern) || + t.is_keyword(keywords::Type) || + t.is_keyword(keywords::Pub)) { + self.bump(); // `default` + Defaultness::Default + } else { + Defaultness::Final + } + } + + fn maybe_consume_incorrect_semicolon(&mut self, items: &[P<Item>]) -> bool { + if self.eat(&token::Semi) { + let mut err = self.struct_span_err(self.prev_span, "expected item, found `;`"); + err.span_suggestion_short( + self.prev_span, + "remove this semicolon", + String::new(), + Applicability::MachineApplicable, + ); + if !items.is_empty() { + let previous_item = &items[items.len()-1]; + let previous_item_kind_name = match previous_item.node { + // say "braced struct" because tuple-structs and + // braceless-empty-struct declarations do take a semicolon + ItemKind::Struct(..) => Some("braced struct"), + ItemKind::Enum(..) => Some("enum"), + ItemKind::Trait(..) => Some("trait"), + ItemKind::Union(..) => Some("union"), + _ => None, + }; + if let Some(name) = previous_item_kind_name { + err.help(&format!("{} declarations are not followed by a semicolon", name)); + } + } + err.emit(); + true + } else { + false + } + } + + /// Given a termination token, parses all of the items in a module. + fn parse_mod_items(&mut self, term: &token::Token, inner_lo: Span) -> PResult<'a, Mod> { + let mut items = vec![]; + while let Some(item) = self.parse_item()? { + items.push(item); + self.maybe_consume_incorrect_semicolon(&items); + } + + if !self.eat(term) { + let token_str = self.this_token_descr(); + if !self.maybe_consume_incorrect_semicolon(&items) { + let mut err = self.fatal(&format!("expected item, found {}", token_str)); + err.span_label(self.span, "expected item"); + return Err(err); + } + } + + let hi = if self.span.is_dummy() { + inner_lo + } else { + self.prev_span + }; + + Ok(ast::Mod { + inner: inner_lo.to(hi), + items, + inline: true + }) + } + + fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> { + let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?; + self.expect(&token::Colon)?; + let ty = self.parse_ty()?; + self.expect(&token::Eq)?; + let e = self.parse_expr()?; + self.expect(&token::Semi)?; + let item = match m { + Some(m) => ItemKind::Static(ty, m, e), + None => ItemKind::Const(ty, e), + }; + Ok((id, item, None)) + } + + /// Parse a `mod <foo> { ... }` or `mod <foo>;` item + fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> { + let (in_cfg, outer_attrs) = { + let mut strip_unconfigured = crate::config::StripUnconfigured { + sess: self.sess, + features: None, // don't perform gated feature checking + }; + let mut outer_attrs = outer_attrs.to_owned(); + strip_unconfigured.process_cfg_attrs(&mut outer_attrs); + (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), outer_attrs) + }; + + let id_span = self.span; + let id = self.parse_ident()?; + if self.eat(&token::Semi) { + if in_cfg && self.recurse_into_file_modules { + // This mod is in an external file. Let's go get it! + let ModulePathSuccess { path, directory_ownership, warn } = + self.submod_path(id, &outer_attrs, id_span)?; + let (module, mut attrs) = + self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?; + // Record that we fetched the mod from an external file + if warn { + let attr = Attribute { + id: attr::mk_attr_id(), + style: ast::AttrStyle::Outer, + path: ast::Path::from_ident(Ident::from_str("warn_directory_ownership")), + tokens: TokenStream::empty(), + is_sugared_doc: false, + span: syntax_pos::DUMMY_SP, + }; + attr::mark_known(&attr); + attrs.push(attr); + } + Ok((id, ItemKind::Mod(module), Some(attrs))) + } else { + let placeholder = ast::Mod { + inner: syntax_pos::DUMMY_SP, + items: Vec::new(), + inline: false + }; + Ok((id, ItemKind::Mod(placeholder), None)) + } + } else { + let old_directory = self.directory.clone(); + self.push_directory(id, &outer_attrs); + + self.expect(&token::OpenDelim(token::Brace))?; + let mod_inner_lo = self.span; + let attrs = self.parse_inner_attributes()?; + let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?; + + self.directory = old_directory; + Ok((id, ItemKind::Mod(module), Some(attrs))) + } + } + + fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) { + if let Some(path) = attr::first_attr_value_str_by_name(attrs, "path") { + self.directory.path.to_mut().push(&path.as_str()); + self.directory.ownership = DirectoryOwnership::Owned { relative: None }; + } else { + // We have to push on the current module name in the case of relative + // paths in order to ensure that any additional module paths from inline + // `mod x { ... }` come after the relative extension. + // + // For example, a `mod z { ... }` inside `x/y.rs` should set the current + // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`. + if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership { + if let Some(ident) = relative.take() { // remove the relative offset + self.directory.path.to_mut().push(ident.as_str()); + } + } + self.directory.path.to_mut().push(&id.as_str()); + } + } + + pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> { + if let Some(s) = attr::first_attr_value_str_by_name(attrs, "path") { + let s = s.as_str(); + + // On windows, the base path might have the form + // `\\?\foo\bar` in which case it does not tolerate + // mixed `/` and `\` separators, so canonicalize + // `/` to `\`. + #[cfg(windows)] + let s = s.replace("/", "\\"); + Some(dir_path.join(s)) + } else { + None + } + } + + /// Returns a path to a module. + pub fn default_submod_path( + id: ast::Ident, + relative: Option<ast::Ident>, + dir_path: &Path, + source_map: &SourceMap) -> ModulePath + { + // If we're in a foo.rs file instead of a mod.rs file, + // we need to look for submodules in + // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than + // `./<id>.rs` and `./<id>/mod.rs`. + let relative_prefix_string; + let relative_prefix = if let Some(ident) = relative { + relative_prefix_string = format!("{}{}", ident.as_str(), path::MAIN_SEPARATOR); + &relative_prefix_string + } else { + "" + }; + + let mod_name = id.to_string(); + let default_path_str = format!("{}{}.rs", relative_prefix, mod_name); + let secondary_path_str = format!("{}{}{}mod.rs", + relative_prefix, mod_name, path::MAIN_SEPARATOR); + let default_path = dir_path.join(&default_path_str); + let secondary_path = dir_path.join(&secondary_path_str); + let default_exists = source_map.file_exists(&default_path); + let secondary_exists = source_map.file_exists(&secondary_path); + + let result = match (default_exists, secondary_exists) { + (true, false) => Ok(ModulePathSuccess { + path: default_path, + directory_ownership: DirectoryOwnership::Owned { + relative: Some(id), + }, + warn: false, + }), + (false, true) => Ok(ModulePathSuccess { + path: secondary_path, + directory_ownership: DirectoryOwnership::Owned { + relative: None, + }, + warn: false, + }), + (false, false) => Err(Error::FileNotFoundForModule { + mod_name: mod_name.clone(), + default_path: default_path_str, + secondary_path: secondary_path_str, + dir_path: dir_path.display().to_string(), + }), + (true, true) => Err(Error::DuplicatePaths { + mod_name: mod_name.clone(), + default_path: default_path_str, + secondary_path: secondary_path_str, + }), + }; + + ModulePath { + name: mod_name, + path_exists: default_exists || secondary_exists, + result, + } + } + + fn submod_path(&mut self, + id: ast::Ident, + outer_attrs: &[Attribute], + id_sp: Span) + -> PResult<'a, ModulePathSuccess> { + if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) { + return Ok(ModulePathSuccess { + directory_ownership: match path.file_name().and_then(|s| s.to_str()) { + // All `#[path]` files are treated as though they are a `mod.rs` file. + // This means that `mod foo;` declarations inside `#[path]`-included + // files are siblings, + // + // Note that this will produce weirdness when a file named `foo.rs` is + // `#[path]` included and contains a `mod foo;` declaration. + // If you encounter this, it's your own darn fault :P + Some(_) => DirectoryOwnership::Owned { relative: None }, + _ => DirectoryOwnership::UnownedViaMod(true), + }, + path, + warn: false, + }); + } + + let relative = match self.directory.ownership { + DirectoryOwnership::Owned { relative } => relative, + DirectoryOwnership::UnownedViaBlock | + DirectoryOwnership::UnownedViaMod(_) => None, + }; + let paths = Parser::default_submod_path( + id, relative, &self.directory.path, self.sess.source_map()); + + match self.directory.ownership { + DirectoryOwnership::Owned { .. } => { + paths.result.map_err(|err| self.span_fatal_err(id_sp, err)) + }, + DirectoryOwnership::UnownedViaBlock => { + let msg = + "Cannot declare a non-inline module inside a block \ + unless it has a path attribute"; + let mut err = self.diagnostic().struct_span_err(id_sp, msg); + if paths.path_exists { + let msg = format!("Maybe `use` the module `{}` instead of redeclaring it", + paths.name); + err.span_note(id_sp, &msg); + } + Err(err) + } + DirectoryOwnership::UnownedViaMod(warn) => { + if warn { + if let Ok(result) = paths.result { + return Ok(ModulePathSuccess { warn: true, ..result }); + } + } + let mut err = self.diagnostic().struct_span_err(id_sp, + "cannot declare a new module at this location"); + if !id_sp.is_dummy() { + let src_path = self.sess.source_map().span_to_filename(id_sp); + if let FileName::Real(src_path) = src_path { + if let Some(stem) = src_path.file_stem() { + let mut dest_path = src_path.clone(); + dest_path.set_file_name(stem); + dest_path.push("mod.rs"); + err.span_note(id_sp, + &format!("maybe move this module `{}` to its own \ + directory via `{}`", src_path.display(), + dest_path.display())); + } + } + } + if paths.path_exists { + err.span_note(id_sp, + &format!("... or maybe `use` the module `{}` instead \ + of possibly redeclaring it", + paths.name)); + } + Err(err) + } + } + } + + /// Reads a module from a source file. + fn eval_src_mod(&mut self, + path: PathBuf, + directory_ownership: DirectoryOwnership, + name: String, + id_sp: Span) + -> PResult<'a, (ast::Mod, Vec<Attribute> )> { + let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut(); + if let Some(i) = included_mod_stack.iter().position(|p| *p == path) { + let mut err = String::from("circular modules: "); + let len = included_mod_stack.len(); + for p in &included_mod_stack[i.. len] { + err.push_str(&p.to_string_lossy()); + err.push_str(" -> "); + } + err.push_str(&path.to_string_lossy()); + return Err(self.span_fatal(id_sp, &err[..])); + } + included_mod_stack.push(path.clone()); + drop(included_mod_stack); + + let mut p0 = + new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp); + p0.cfg_mods = self.cfg_mods; + let mod_inner_lo = p0.span; + let mod_attrs = p0.parse_inner_attributes()?; + let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?; + m0.inline = false; + self.sess.included_mod_stack.borrow_mut().pop(); + Ok((m0, mod_attrs)) + } + + /// Parses a function declaration from a foreign module. + fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>) + -> PResult<'a, ForeignItem> { + self.expect_keyword(keywords::Fn)?; + + let (ident, mut generics) = self.parse_fn_header()?; + let decl = self.parse_fn_decl(true)?; + generics.where_clause = self.parse_where_clause()?; + let hi = self.span; + self.expect(&token::Semi)?; + Ok(ast::ForeignItem { + ident, + attrs, + node: ForeignItemKind::Fn(decl, generics), + id: ast::DUMMY_NODE_ID, + span: lo.to(hi), + vis, + }) + } + + /// Parses a static item from a foreign module. + /// Assumes that the `static` keyword is already parsed. + fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>) + -> PResult<'a, ForeignItem> { + let mutbl = self.eat_keyword(keywords::Mut); + let ident = self.parse_ident()?; + self.expect(&token::Colon)?; + let ty = self.parse_ty()?; + let hi = self.span; + self.expect(&token::Semi)?; + Ok(ForeignItem { + ident, + attrs, + node: ForeignItemKind::Static(ty, mutbl), + id: ast::DUMMY_NODE_ID, + span: lo.to(hi), + vis, + }) + } + + /// Parses a type from a foreign module. + fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>) + -> PResult<'a, ForeignItem> { + self.expect_keyword(keywords::Type)?; + + let ident = self.parse_ident()?; + let hi = self.span; + self.expect(&token::Semi)?; + Ok(ast::ForeignItem { + ident: ident, + attrs: attrs, + node: ForeignItemKind::Ty, + id: ast::DUMMY_NODE_ID, + span: lo.to(hi), + vis: vis + }) + } + + fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> { + let error_msg = "crate name using dashes are not valid in `extern crate` statements"; + let suggestion_msg = "if the original crate name uses dashes you need to use underscores \ + in the code"; + let mut ident = if self.token.is_keyword(keywords::SelfLower) { + self.parse_path_segment_ident() + } else { + self.parse_ident() + }?; + let mut idents = vec![]; + let mut replacement = vec![]; + let mut fixed_crate_name = false; + // Accept `extern crate name-like-this` for better diagnostics + let dash = token::Token::BinOp(token::BinOpToken::Minus); + if self.token == dash { // Do not include `-` as part of the expected tokens list + while self.eat(&dash) { + fixed_crate_name = true; + replacement.push((self.prev_span, "_".to_string())); + idents.push(self.parse_ident()?); + } + } + if fixed_crate_name { + let fixed_name_sp = ident.span.to(idents.last().unwrap().span); + let mut fixed_name = format!("{}", ident.name); + for part in idents { + fixed_name.push_str(&format!("_{}", part.name)); + } + ident = Ident::from_str(&fixed_name).with_span_pos(fixed_name_sp); + + let mut err = self.struct_span_err(fixed_name_sp, error_msg); + err.span_label(fixed_name_sp, "dash-separated idents are not valid"); + err.multipart_suggestion( + suggestion_msg, + replacement, + Applicability::MachineApplicable, + ); + err.emit(); + } + Ok(ident) + } + + /// Parses `extern crate` links. + /// + /// # Examples + /// + /// ``` + /// extern crate foo; + /// extern crate bar as foo; + /// ``` + fn parse_item_extern_crate(&mut self, + lo: Span, + visibility: Visibility, + attrs: Vec<Attribute>) + -> PResult<'a, P<Item>> { + // Accept `extern crate name-like-this` for better diagnostics + let orig_name = self.parse_crate_name_with_dashes()?; + let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? { + (rename, Some(orig_name.name)) + } else { + (orig_name, None) + }; + self.expect(&token::Semi)?; + + let span = lo.to(self.prev_span); + Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs)) + } + + /// Parses `extern` for foreign ABIs modules. + /// + /// `extern` is expected to have been + /// consumed before calling this method. + /// + /// # Examples + /// + /// ```ignore (only-for-syntax-highlight) + /// extern "C" {} + /// extern {} + /// ``` + fn parse_item_foreign_mod(&mut self, + lo: Span, + opt_abi: Option<Abi>, + visibility: Visibility, + mut attrs: Vec<Attribute>) + -> PResult<'a, P<Item>> { + self.expect(&token::OpenDelim(token::Brace))?; + + let abi = opt_abi.unwrap_or(Abi::C); + + attrs.extend(self.parse_inner_attributes()?); + + let mut foreign_items = vec![]; + while !self.eat(&token::CloseDelim(token::Brace)) { + foreign_items.push(self.parse_foreign_item()?); + } + + let prev_span = self.prev_span; + let m = ast::ForeignMod { + abi, + items: foreign_items + }; + let invalid = keywords::Invalid.ident(); + Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs)) + } + + /// Parses `type Foo = Bar;` + /// or + /// `existential type Foo: Bar;` + /// or + /// `return `None`` + /// without modifying the parser state. + fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> { + // This parses the grammar: + // Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";" + if self.check_keyword(keywords::Type) || + self.check_keyword(keywords::Existential) && + self.look_ahead(1, |t| t.is_keyword(keywords::Type)) { + let existential = self.eat_keyword(keywords::Existential); + assert!(self.eat_keyword(keywords::Type)); + Some(self.parse_existential_or_alias(existential)) + } else { + None + } + } + + /// Parses a type alias or existential type. + fn parse_existential_or_alias( + &mut self, + existential: bool, + ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> { + let ident = self.parse_ident()?; + let mut tps = self.parse_generics()?; + tps.where_clause = self.parse_where_clause()?; + let alias = if existential { + self.expect(&token::Colon)?; + let bounds = self.parse_generic_bounds(None)?; + AliasKind::Existential(bounds) + } else { + self.expect(&token::Eq)?; + let ty = self.parse_ty()?; + AliasKind::Weak(ty) + }; + self.expect(&token::Semi)?; + Ok((ident, alias, tps)) + } + + /// Parses the part of an enum declaration following the `{`. + fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> { + let mut variants = Vec::new(); + let mut all_nullary = true; + let mut any_disr = vec![]; + while self.token != token::CloseDelim(token::Brace) { + let variant_attrs = self.parse_outer_attributes()?; + let vlo = self.span; + + let struct_def; + let mut disr_expr = None; + let ident = self.parse_ident()?; + if self.check(&token::OpenDelim(token::Brace)) { + // Parse a struct variant. + all_nullary = false; + struct_def = VariantData::Struct(self.parse_record_struct_body()?, + ast::DUMMY_NODE_ID); + } else if self.check(&token::OpenDelim(token::Paren)) { + all_nullary = false; + struct_def = VariantData::Tuple(self.parse_tuple_struct_body()?, + ast::DUMMY_NODE_ID); + } else if self.eat(&token::Eq) { + disr_expr = Some(AnonConst { + id: ast::DUMMY_NODE_ID, + value: self.parse_expr()?, + }); + if let Some(sp) = disr_expr.as_ref().map(|c| c.value.span) { + any_disr.push(sp); + } + struct_def = VariantData::Unit(ast::DUMMY_NODE_ID); + } else { + struct_def = VariantData::Unit(ast::DUMMY_NODE_ID); + } + + let vr = ast::Variant_ { + ident, + attrs: variant_attrs, + data: struct_def, + disr_expr, + }; + variants.push(respan(vlo.to(self.prev_span), vr)); + + if !self.eat(&token::Comma) { break; } + } + self.expect(&token::CloseDelim(token::Brace))?; + if !any_disr.is_empty() && !all_nullary { + let mut err =self.struct_span_err( + any_disr.clone(), + "discriminator values can only be used with a field-less enum", + ); + for sp in any_disr { + err.span_label(sp, "only valid in field-less enums"); + } + err.emit(); + } + + Ok(ast::EnumDef { variants }) + } + + /// Parses an enum declaration. + fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> { + let id = self.parse_ident()?; + let mut generics = self.parse_generics()?; + generics.where_clause = self.parse_where_clause()?; + self.expect(&token::OpenDelim(token::Brace))?; + + let enum_definition = self.parse_enum_def(&generics).map_err(|e| { + self.recover_stmt(); + self.eat(&token::CloseDelim(token::Brace)); + e + })?; + Ok((id, ItemKind::Enum(enum_definition, generics), None)) + } + + /// Parses a string as an ABI spec on an extern type or module. Consumes + /// the `extern` keyword, if one is found. + fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> { + match self.token { + token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => { + let sp = self.span; + self.expect_no_suffix(sp, "ABI spec", suf); + self.bump(); + match abi::lookup(&s.as_str()) { + Some(abi) => Ok(Some(abi)), + None => { + let prev_span = self.prev_span; + let mut err = struct_span_err!( + self.sess.span_diagnostic, + prev_span, + E0703, + "invalid ABI: found `{}`", + s); + err.span_label(prev_span, "invalid ABI"); + err.help(&format!("valid ABIs: {}", abi::all_names().join(", "))); + err.emit(); + Ok(None) + } + } + } + + _ => Ok(None), + } + } + + fn is_static_global(&mut self) -> bool { + if self.check_keyword(keywords::Static) { + // Check if this could be a closure + !self.look_ahead(1, |token| { + if token.is_keyword(keywords::Move) { + return true; + } + match *token { + token::BinOp(token::Or) | token::OrOr => true, + _ => false, + } + }) + } else { + false + } + } + + fn parse_item_( + &mut self, + attrs: Vec<Attribute>, + macros_allowed: bool, + attributes_allowed: bool, + ) -> PResult<'a, Option<P<Item>>> { + let (ret, tokens) = self.collect_tokens(|this| { + this.parse_item_implementation(attrs, macros_allowed, attributes_allowed) + })?; + + // Once we've parsed an item and recorded the tokens we got while + // parsing we may want to store `tokens` into the item we're about to + // return. Note, though, that we specifically didn't capture tokens + // related to outer attributes. The `tokens` field here may later be + // used with procedural macros to convert this item back into a token + // stream, but during expansion we may be removing attributes as we go + // along. + // + // If we've got inner attributes then the `tokens` we've got above holds + // these inner attributes. If an inner attribute is expanded we won't + // actually remove it from the token stream, so we'll just keep yielding + // it (bad!). To work around this case for now we just avoid recording + // `tokens` if we detect any inner attributes. This should help keep + // expansion correct, but we should fix this bug one day! + Ok(ret.map(|item| { + item.map(|mut i| { + if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) { + i.tokens = Some(tokens); + } + i + }) + })) + } + + /// Parses one of the items allowed by the flags. + fn parse_item_implementation( + &mut self, + attrs: Vec<Attribute>, + macros_allowed: bool, + attributes_allowed: bool, + ) -> PResult<'a, Option<P<Item>>> { + maybe_whole!(self, NtItem, |item| { + let mut item = item.into_inner(); + let mut attrs = attrs; + mem::swap(&mut item.attrs, &mut attrs); + item.attrs.extend(attrs); + Some(P(item)) + }); + + let lo = self.span; + + let visibility = self.parse_visibility(false)?; + + if self.eat_keyword(keywords::Use) { + // USE ITEM + let item_ = ItemKind::Use(P(self.parse_use_tree()?)); + self.expect(&token::Semi)?; + + let span = lo.to(self.prev_span); + let item = self.mk_item(span, keywords::Invalid.ident(), item_, visibility, attrs); + return Ok(Some(item)); + } + + if self.eat_keyword(keywords::Extern) { + if self.eat_keyword(keywords::Crate) { + return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?)); + } + + let opt_abi = self.parse_opt_abi()?; + + if self.eat_keyword(keywords::Fn) { + // EXTERN FUNCTION ITEM + let fn_span = self.prev_span; + let abi = opt_abi.unwrap_or(Abi::C); + let (ident, item_, extra_attrs) = + self.parse_item_fn(Unsafety::Normal, + IsAsync::NotAsync, + respan(fn_span, Constness::NotConst), + abi)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } else if self.check(&token::OpenDelim(token::Brace)) { + return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?)); + } + + self.unexpected()?; + } + + if self.is_static_global() { + self.bump(); + // STATIC ITEM + let m = if self.eat_keyword(keywords::Mut) { + Mutability::Mutable + } else { + Mutability::Immutable + }; + let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.eat_keyword(keywords::Const) { + let const_span = self.prev_span; + if self.check_keyword(keywords::Fn) + || (self.check_keyword(keywords::Unsafe) + && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) { + // CONST FUNCTION ITEM + let unsafety = self.parse_unsafety(); + self.bump(); + let (ident, item_, extra_attrs) = + self.parse_item_fn(unsafety, + IsAsync::NotAsync, + respan(const_span, Constness::Const), + Abi::Rust)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + + // CONST ITEM + if self.eat_keyword(keywords::Mut) { + let prev_span = self.prev_span; + let mut err = self.diagnostic() + .struct_span_err(prev_span, "const globals cannot be mutable"); + err.span_label(prev_span, "cannot be mutable"); + err.span_suggestion( + const_span, + "you might want to declare a static instead", + "static".to_owned(), + Applicability::MaybeIncorrect, + ); + err.emit(); + } + let (ident, item_, extra_attrs) = self.parse_item_const(None)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + + // `unsafe async fn` or `async fn` + if ( + self.check_keyword(keywords::Unsafe) && + self.look_ahead(1, |t| t.is_keyword(keywords::Async)) + ) || ( + self.check_keyword(keywords::Async) && + self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) + ) + { + // ASYNC FUNCTION ITEM + let unsafety = self.parse_unsafety(); + self.expect_keyword(keywords::Async)?; + self.expect_keyword(keywords::Fn)?; + let fn_span = self.prev_span; + let (ident, item_, extra_attrs) = + self.parse_item_fn(unsafety, + IsAsync::Async { + closure_id: ast::DUMMY_NODE_ID, + return_impl_trait_id: ast::DUMMY_NODE_ID, + }, + respan(fn_span, Constness::NotConst), + Abi::Rust)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.check_keyword(keywords::Unsafe) && + (self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) || + self.look_ahead(1, |t| t.is_keyword(keywords::Auto))) + { + // UNSAFE TRAIT ITEM + self.bump(); // `unsafe` + let is_auto = if self.eat_keyword(keywords::Trait) { + IsAuto::No + } else { + self.expect_keyword(keywords::Auto)?; + self.expect_keyword(keywords::Trait)?; + IsAuto::Yes + }; + let (ident, item_, extra_attrs) = + self.parse_item_trait(is_auto, Unsafety::Unsafe)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.check_keyword(keywords::Impl) || + self.check_keyword(keywords::Unsafe) && + self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) || + self.check_keyword(keywords::Default) && + self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) || + self.check_keyword(keywords::Default) && + self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) { + // IMPL ITEM + let defaultness = self.parse_defaultness(); + let unsafety = self.parse_unsafety(); + self.expect_keyword(keywords::Impl)?; + let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?; + let span = lo.to(self.prev_span); + return Ok(Some(self.mk_item(span, ident, item, visibility, + maybe_append(attrs, extra_attrs)))); + } + if self.check_keyword(keywords::Fn) { + // FUNCTION ITEM + self.bump(); + let fn_span = self.prev_span; + let (ident, item_, extra_attrs) = + self.parse_item_fn(Unsafety::Normal, + IsAsync::NotAsync, + respan(fn_span, Constness::NotConst), + Abi::Rust)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.check_keyword(keywords::Unsafe) + && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) { + // UNSAFE FUNCTION ITEM + self.bump(); // `unsafe` + // `{` is also expected after `unsafe`, in case of error, include it in the diagnostic + self.check(&token::OpenDelim(token::Brace)); + let abi = if self.eat_keyword(keywords::Extern) { + self.parse_opt_abi()?.unwrap_or(Abi::C) + } else { + Abi::Rust + }; + self.expect_keyword(keywords::Fn)?; + let fn_span = self.prev_span; + let (ident, item_, extra_attrs) = + self.parse_item_fn(Unsafety::Unsafe, + IsAsync::NotAsync, + respan(fn_span, Constness::NotConst), + abi)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.eat_keyword(keywords::Mod) { + // MODULE ITEM + let (ident, item_, extra_attrs) = + self.parse_item_mod(&attrs[..])?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if let Some(type_) = self.eat_type() { + let (ident, alias, generics) = type_?; + // TYPE ITEM + let item_ = match alias { + AliasKind::Weak(ty) => ItemKind::Ty(ty, generics), + AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics), + }; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + attrs); + return Ok(Some(item)); + } + if self.eat_keyword(keywords::Enum) { + // ENUM ITEM + let (ident, item_, extra_attrs) = self.parse_item_enum()?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.check_keyword(keywords::Trait) + || (self.check_keyword(keywords::Auto) + && self.look_ahead(1, |t| t.is_keyword(keywords::Trait))) + { + let is_auto = if self.eat_keyword(keywords::Trait) { + IsAuto::No + } else { + self.expect_keyword(keywords::Auto)?; + self.expect_keyword(keywords::Trait)?; + IsAuto::Yes + }; + // TRAIT ITEM + let (ident, item_, extra_attrs) = + self.parse_item_trait(is_auto, Unsafety::Normal)?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.eat_keyword(keywords::Struct) { + // STRUCT ITEM + let (ident, item_, extra_attrs) = self.parse_item_struct()?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if self.is_union_item() { + // UNION ITEM + self.bump(); + let (ident, item_, extra_attrs) = self.parse_item_union()?; + let prev_span = self.prev_span; + let item = self.mk_item(lo.to(prev_span), + ident, + item_, + visibility, + maybe_append(attrs, extra_attrs)); + return Ok(Some(item)); + } + if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, lo)? { + return Ok(Some(macro_def)); + } + + // Verify whether we have encountered a struct or method definition where the user forgot to + // add the `struct` or `fn` keyword after writing `pub`: `pub S {}` + if visibility.node.is_pub() && + self.check_ident() && + self.look_ahead(1, |t| *t != token::Not) + { + // Space between `pub` keyword and the identifier + // + // pub S {} + // ^^^ `sp` points here + let sp = self.prev_span.between(self.span); + let full_sp = self.prev_span.to(self.span); + let ident_sp = self.span; + if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) { + // possible public struct definition where `struct` was forgotten + let ident = self.parse_ident().unwrap(); + let msg = format!("add `struct` here to parse `{}` as a public struct", + ident); + let mut err = self.diagnostic() + .struct_span_err(sp, "missing `struct` for struct definition"); + err.span_suggestion_short( + sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative + ); + return Err(err); + } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) { + let ident = self.parse_ident().unwrap(); + self.bump(); // `(` + let kw_name = if let Ok(Some(_)) = self.parse_self_arg() { + "method" + } else { + "function" + }; + self.consume_block(token::Paren); + let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) { + self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]); + self.bump(); // `{` + ("fn", kw_name, false) + } else if self.check(&token::OpenDelim(token::Brace)) { + self.bump(); // `{` + ("fn", kw_name, false) + } else if self.check(&token::Colon) { + let kw = "struct"; + (kw, kw, false) + } else { + ("fn` or `struct", "function or struct", true) + }; + self.consume_block(token::Brace); + + let msg = format!("missing `{}` for {} definition", kw, kw_name); + let mut err = self.diagnostic().struct_span_err(sp, &msg); + if !ambiguous { + let suggestion = format!("add `{}` here to parse `{}` as a public {}", + kw, + ident, + kw_name); + err.span_suggestion_short( + sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable + ); + } else { + if let Ok(snippet) = self.sess.source_map().span_to_snippet(ident_sp) { + err.span_suggestion( + full_sp, + "if you meant to call a macro, try", + format!("{}!", snippet), + // this is the `ambiguous` conditional branch + Applicability::MaybeIncorrect + ); + } else { + err.help("if you meant to call a macro, remove the `pub` \ + and add a trailing `!` after the identifier"); + } + } + return Err(err); + } else if self.look_ahead(1, |t| *t == token::Lt) { + let ident = self.parse_ident().unwrap(); + self.eat_to_tokens(&[&token::Gt]); + self.bump(); // `>` + let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) { + if let Ok(Some(_)) = self.parse_self_arg() { + ("fn", "method", false) + } else { + ("fn", "function", false) + } + } else if self.check(&token::OpenDelim(token::Brace)) { + ("struct", "struct", false) + } else { + ("fn` or `struct", "function or struct", true) + }; + let msg = format!("missing `{}` for {} definition", kw, kw_name); + let mut err = self.diagnostic().struct_span_err(sp, &msg); + if !ambiguous { + err.span_suggestion_short( + sp, + &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name), + format!(" {} ", kw), + Applicability::MachineApplicable, + ); + } + return Err(err); + } + } + self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, visibility) + } + + /// Parses a foreign item. + crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> { + maybe_whole!(self, NtForeignItem, |ni| ni); + + let attrs = self.parse_outer_attributes()?; + let lo = self.span; + let visibility = self.parse_visibility(false)?; + + // FOREIGN STATIC ITEM + // Treat `const` as `static` for error recovery, but don't add it to expected tokens. + if self.check_keyword(keywords::Static) || self.token.is_keyword(keywords::Const) { + if self.token.is_keyword(keywords::Const) { + self.diagnostic() + .struct_span_err(self.span, "extern items cannot be `const`") + .span_suggestion( + self.span, + "try using a static value", + "static".to_owned(), + Applicability::MachineApplicable + ).emit(); + } + self.bump(); // `static` or `const` + return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?); + } + // FOREIGN FUNCTION ITEM + if self.check_keyword(keywords::Fn) { + return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?); + } + // FOREIGN TYPE ITEM + if self.check_keyword(keywords::Type) { + return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?); + } + + match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? { + Some(mac) => { + Ok( + ForeignItem { + ident: keywords::Invalid.ident(), + span: lo.to(self.prev_span), + id: ast::DUMMY_NODE_ID, + attrs, + vis: visibility, + node: ForeignItemKind::Macro(mac), + } + ) + } + None => { + if !attrs.is_empty() { + self.expected_item_err(&attrs)?; + } + + self.unexpected() + } + } + } + + /// This is the fall-through for parsing items. + fn parse_macro_use_or_failure( + &mut self, + attrs: Vec<Attribute> , + macros_allowed: bool, + attributes_allowed: bool, + lo: Span, + visibility: Visibility + ) -> PResult<'a, Option<P<Item>>> { + if macros_allowed && self.token.is_path_start() { + // MACRO INVOCATION ITEM + + let prev_span = self.prev_span; + self.complain_if_pub_macro(&visibility.node, prev_span); + + let mac_lo = self.span; + + // item macro. + let pth = self.parse_path(PathStyle::Mod)?; + self.expect(&token::Not)?; + + // a 'special' identifier (like what `macro_rules!` uses) + // is optional. We should eventually unify invoc syntax + // and remove this. + let id = if self.token.is_ident() { + self.parse_ident()? + } else { + keywords::Invalid.ident() // no special identifier + }; + // eat a matched-delimiter token tree: + let (delim, tts) = self.expect_delimited_token_tree()?; + if delim != MacDelimiter::Brace { + if !self.eat(&token::Semi) { + self.span_err(self.prev_span, + "macros that expand to items must either \ + be surrounded with braces or followed by \ + a semicolon"); + } + } + + let hi = self.prev_span; + let mac = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim }); + let item = self.mk_item(lo.to(hi), id, ItemKind::Mac(mac), visibility, attrs); + return Ok(Some(item)); + } + + // FAILURE TO PARSE ITEM + match visibility.node { + VisibilityKind::Inherited => {} + _ => { + return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`")); + } + } + + if !attributes_allowed && !attrs.is_empty() { + self.expected_item_err(&attrs)?; + } + Ok(None) + } + + /// Parses a macro invocation inside a `trait`, `impl` or `extern` block. + fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>, + at_end: &mut bool) -> PResult<'a, Option<Mac>> + { + if self.token.is_path_start() { + let prev_span = self.prev_span; + let lo = self.span; + let pth = self.parse_path(PathStyle::Mod)?; + + if pth.segments.len() == 1 { + if !self.eat(&token::Not) { + return Err(self.missing_assoc_item_kind_err(item_kind, prev_span)); + } + } else { + self.expect(&token::Not)?; + } + + if let Some(vis) = vis { + self.complain_if_pub_macro(&vis.node, prev_span); + } + + *at_end = true; + + // eat a matched-delimiter token tree: + let (delim, tts) = self.expect_delimited_token_tree()?; + if delim != MacDelimiter::Brace { + self.expect(&token::Semi)?; + } + + Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim }))) + } else { + Ok(None) + } + } + + fn collect_tokens<F, R>(&mut self, f: F) -> PResult<'a, (R, TokenStream)> + where F: FnOnce(&mut Self) -> PResult<'a, R> + { + // Record all tokens we parse when parsing this item. + let mut tokens = Vec::new(); + let prev_collecting = match self.token_cursor.frame.last_token { + LastToken::Collecting(ref mut list) => { + Some(mem::replace(list, Vec::new())) + } + LastToken::Was(ref mut last) => { + tokens.extend(last.take()); + None + } + }; + self.token_cursor.frame.last_token = LastToken::Collecting(tokens); + let prev = self.token_cursor.stack.len(); + let ret = f(self); + let last_token = if self.token_cursor.stack.len() == prev { + &mut self.token_cursor.frame.last_token + } else { + &mut self.token_cursor.stack[prev].last_token + }; + + // Pull out the tokens that we've collected from the call to `f` above. + let mut collected_tokens = match *last_token { + LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()), + LastToken::Was(_) => panic!("our vector went away?"), + }; + + // If we're not at EOF our current token wasn't actually consumed by + // `f`, but it'll still be in our list that we pulled out. In that case + // put it back. + let extra_token = if self.token != token::Eof { + collected_tokens.pop() + } else { + None + }; + + // If we were previously collecting tokens, then this was a recursive + // call. In that case we need to record all the tokens we collected in + // our parent list as well. To do that we push a clone of our stream + // onto the previous list. + match prev_collecting { + Some(mut list) => { + list.extend(collected_tokens.iter().cloned()); + list.extend(extra_token); + *last_token = LastToken::Collecting(list); + } + None => { + *last_token = LastToken::Was(extra_token); + } + } + + Ok((ret?, TokenStream::new(collected_tokens))) + } + + pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> { + let attrs = self.parse_outer_attributes()?; + self.parse_item_(attrs, true, false) + } + + /// `::{` or `::*` + fn is_import_coupler(&mut self) -> bool { + self.check(&token::ModSep) && + self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) || + *t == token::BinOp(token::Star)) + } + + /// Parses a `UseTree`. + /// + /// ``` + /// USE_TREE = [`::`] `*` | + /// [`::`] `{` USE_TREE_LIST `}` | + /// PATH `::` `*` | + /// PATH `::` `{` USE_TREE_LIST `}` | + /// PATH [`as` IDENT] + /// ``` + fn parse_use_tree(&mut self) -> PResult<'a, UseTree> { + let lo = self.span; + + let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() }; + let kind = if self.check(&token::OpenDelim(token::Brace)) || + self.check(&token::BinOp(token::Star)) || + self.is_import_coupler() { + // `use *;` or `use ::*;` or `use {...};` or `use ::{...};` + let mod_sep_ctxt = self.span.ctxt(); + if self.eat(&token::ModSep) { + prefix.segments.push( + PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)) + ); + } + + if self.eat(&token::BinOp(token::Star)) { + UseTreeKind::Glob + } else { + UseTreeKind::Nested(self.parse_use_tree_list()?) + } + } else { + // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;` + prefix = self.parse_path(PathStyle::Mod)?; + + if self.eat(&token::ModSep) { + if self.eat(&token::BinOp(token::Star)) { + UseTreeKind::Glob + } else { + UseTreeKind::Nested(self.parse_use_tree_list()?) + } + } else { + UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID) + } + }; + + Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) }) + } + + /// Parses a `UseTreeKind::Nested(list)`. + /// + /// ``` + /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`] + /// ``` + fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> { + self.parse_unspanned_seq(&token::OpenDelim(token::Brace), + &token::CloseDelim(token::Brace), + SeqSep::trailing_allowed(token::Comma), |this| { + Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID)) + }) + } + + fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> { + if self.eat_keyword(keywords::As) { + self.parse_ident_or_underscore().map(Some) + } else { + Ok(None) + } + } + + /// Parses a source module as a crate. This is the main entry point for the parser. + pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> { + let lo = self.span; + let krate = Ok(ast::Crate { + attrs: self.parse_inner_attributes()?, + module: self.parse_mod_items(&token::Eof, lo)?, + span: lo.to(self.span), + }); + emit_unclosed_delims(&self.unclosed_delims, self.diagnostic()); + self.unclosed_delims.clear(); + krate + } + + pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> { + let ret = match self.token { + token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf), + token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf), + _ => return None + }; + self.bump(); + Some(ret) + } + + pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> { + match self.parse_optional_str() { + Some((s, style, suf)) => { + let sp = self.prev_span; + self.expect_no_suffix(sp, "string literal", suf); + Ok((s, style)) + } + _ => { + let msg = "expected string literal"; + let mut err = self.fatal(msg); + err.span_label(self.span, msg); + Err(err) + } + } + } +} + +pub fn emit_unclosed_delims(unclosed_delims: &[UnmatchedBrace], handler: &errors::Handler) { + for unmatched in unclosed_delims { + let mut err = handler.struct_span_err(unmatched.found_span, &format!( + "incorrect close delimiter: `{}`", + pprust::token_to_string(&token::Token::CloseDelim(unmatched.found_delim)), + )); + err.span_label(unmatched.found_span, "incorrect close delimiter"); + if let Some(sp) = unmatched.candidate_span { + err.span_label(sp, "close delimiter possibly meant for this"); + } + if let Some(sp) = unmatched.unclosed_span { + err.span_label(sp, "un-closed delimiter"); + } + err.emit(); + } +} |