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Diffstat (limited to 'compiler/rustc_parse/src/parser/mod.rs')
| -rw-r--r-- | compiler/rustc_parse/src/parser/mod.rs | 1481 |
1 files changed, 1481 insertions, 0 deletions
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs new file mode 100644 index 000000000..0c523ad22 --- /dev/null +++ b/compiler/rustc_parse/src/parser/mod.rs @@ -0,0 +1,1481 @@ +pub mod attr; +mod attr_wrapper; +mod diagnostics; +mod expr; +mod generics; +mod item; +mod nonterminal; +mod pat; +mod path; +mod stmt; +mod ty; + +use crate::lexer::UnmatchedBrace; +pub use attr_wrapper::AttrWrapper; +pub use diagnostics::AttemptLocalParseRecovery; +use diagnostics::Error; +pub(crate) use item::FnParseMode; +pub use pat::{CommaRecoveryMode, RecoverColon, RecoverComma}; +pub use path::PathStyle; + +use rustc_ast::ptr::P; +use rustc_ast::token::{self, Delimiter, Nonterminal, Token, TokenKind}; +use rustc_ast::tokenstream::AttributesData; +use rustc_ast::tokenstream::{self, DelimSpan, Spacing}; +use rustc_ast::tokenstream::{TokenStream, TokenTree}; +use rustc_ast::AttrId; +use rustc_ast::DUMMY_NODE_ID; +use rustc_ast::{self as ast, AnonConst, AttrStyle, AttrVec, Const, Extern}; +use rustc_ast::{Async, Expr, ExprKind, MacArgs, MacArgsEq, MacDelimiter, Mutability, StrLit}; +use rustc_ast::{HasAttrs, HasTokens, Unsafe, Visibility, VisibilityKind}; +use rustc_ast_pretty::pprust; +use rustc_data_structures::fx::FxHashMap; +use rustc_errors::PResult; +use rustc_errors::{ + struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, FatalError, MultiSpan, +}; +use rustc_session::parse::ParseSess; +use rustc_span::source_map::{Span, DUMMY_SP}; +use rustc_span::symbol::{kw, sym, Ident, Symbol}; +use tracing::debug; + +use std::ops::Range; +use std::{cmp, mem, slice}; + +bitflags::bitflags! { + struct Restrictions: u8 { + const STMT_EXPR = 1 << 0; + const NO_STRUCT_LITERAL = 1 << 1; + const CONST_EXPR = 1 << 2; + const ALLOW_LET = 1 << 3; + } +} + +#[derive(Clone, Copy, PartialEq, Debug)] +enum SemiColonMode { + Break, + Ignore, + Comma, +} + +#[derive(Clone, Copy, PartialEq, Debug)] +enum BlockMode { + Break, + Ignore, +} + +/// Whether or not we should force collection of tokens for an AST node, +/// regardless of whether or not it has attributes +#[derive(Clone, Copy, PartialEq)] +pub enum ForceCollect { + Yes, + No, +} + +#[derive(Debug, Eq, PartialEq)] +pub enum TrailingToken { + None, + Semi, + /// If the trailing token is a comma, then capture it + /// Otherwise, ignore the trailing token + MaybeComma, +} + +/// Like `maybe_whole_expr`, but for things other than expressions. +#[macro_export] +macro_rules! maybe_whole { + ($p:expr, $constructor:ident, |$x:ident| $e:expr) => { + if let token::Interpolated(nt) = &$p.token.kind { + if let token::$constructor(x) = &**nt { + let $x = x.clone(); + $p.bump(); + return Ok($e); + } + } + }; +} + +/// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`. +#[macro_export] +macro_rules! maybe_recover_from_interpolated_ty_qpath { + ($self: expr, $allow_qpath_recovery: expr) => { + if $allow_qpath_recovery + && $self.look_ahead(1, |t| t == &token::ModSep) + && let token::Interpolated(nt) = &$self.token.kind + && let token::NtTy(ty) = &**nt + { + let ty = ty.clone(); + $self.bump(); + return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_token.span, ty); + } + }; +} + +#[derive(Clone)] +pub struct Parser<'a> { + pub sess: &'a ParseSess, + /// The current token. + pub token: Token, + /// The spacing for the current token + pub token_spacing: Spacing, + /// The previous token. + pub prev_token: Token, + pub capture_cfg: bool, + restrictions: Restrictions, + expected_tokens: Vec<TokenType>, + // Important: This must only be advanced from `bump` to ensure that + // `token_cursor.num_next_calls` is updated properly. + token_cursor: TokenCursor, + desugar_doc_comments: 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. + unmatched_angle_bracket_count: u32, + max_angle_bracket_count: u32, + /// A 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. + pub(super) unclosed_delims: Vec<UnmatchedBrace>, + last_unexpected_token_span: Option<Span>, + /// Span pointing at the `:` for the last type ascription the parser has seen, and whether it + /// looked like it could have been a mistyped path or literal `Option:Some(42)`). + pub last_type_ascription: Option<(Span, bool /* likely path typo */)>, + /// If present, this `Parser` is not parsing Rust code but rather a macro call. + subparser_name: Option<&'static str>, + capture_state: CaptureState, + /// This allows us to recover when the user forget to add braces around + /// multiple statements in the closure body. + pub current_closure: Option<ClosureSpans>, +} + +// This type is used a lot, e.g. it's cloned when matching many declarative macro rules. Make sure +// it doesn't unintentionally get bigger. +#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] +rustc_data_structures::static_assert_size!(Parser<'_>, 328); + +/// Stores span information about a closure. +#[derive(Clone)] +pub struct ClosureSpans { + pub whole_closure: Span, + pub closing_pipe: Span, + pub body: Span, +} + +/// Indicates a range of tokens that should be replaced by +/// the tokens in the provided vector. This is used in two +/// places during token collection: +/// +/// 1. During the parsing of an AST node that may have a `#[derive]` +/// attribute, we parse a nested AST node that has `#[cfg]` or `#[cfg_attr]` +/// In this case, we use a `ReplaceRange` to replace the entire inner AST node +/// with `FlatToken::AttrTarget`, allowing us to perform eager cfg-expansion +/// on an `AttrAnnotatedTokenStream` +/// +/// 2. When we parse an inner attribute while collecting tokens. We +/// remove inner attributes from the token stream entirely, and +/// instead track them through the `attrs` field on the AST node. +/// This allows us to easily manipulate them (for example, removing +/// the first macro inner attribute to invoke a proc-macro). +/// When create a `TokenStream`, the inner attributes get inserted +/// into the proper place in the token stream. +pub type ReplaceRange = (Range<u32>, Vec<(FlatToken, Spacing)>); + +/// Controls how we capture tokens. Capturing can be expensive, +/// so we try to avoid performing capturing in cases where +/// we will never need an `AttrAnnotatedTokenStream` +#[derive(Copy, Clone)] +pub enum Capturing { + /// We aren't performing any capturing - this is the default mode. + No, + /// We are capturing tokens + Yes, +} + +#[derive(Clone)] +struct CaptureState { + capturing: Capturing, + replace_ranges: Vec<ReplaceRange>, + inner_attr_ranges: FxHashMap<AttrId, ReplaceRange>, +} + +impl<'a> Drop for Parser<'a> { + fn drop(&mut self) { + emit_unclosed_delims(&mut self.unclosed_delims, &self.sess); + } +} + +#[derive(Clone)] +struct TokenCursor { + // The current (innermost) frame. `frame` and `stack` could be combined, + // but it's faster to have them separately to access `frame` directly + // rather than via something like `stack.last().unwrap()` or + // `stack[stack.len() - 1]`. + frame: TokenCursorFrame, + // Additional frames that enclose `frame`. + stack: Vec<TokenCursorFrame>, + desugar_doc_comments: bool, + // Counts the number of calls to `{,inlined_}next`. + num_next_calls: usize, + // During parsing, we may sometimes need to 'unglue' a + // glued token into two component tokens + // (e.g. '>>' into '>' and '>), so that the parser + // can consume them one at a time. This process + // bypasses the normal capturing mechanism + // (e.g. `num_next_calls` will not be incremented), + // since the 'unglued' tokens due not exist in + // the original `TokenStream`. + // + // If we end up consuming both unglued tokens, + // then this is not an issue - we'll end up + // capturing the single 'glued' token. + // + // However, in certain circumstances, we may + // want to capture just the first 'unglued' token. + // For example, capturing the `Vec<u8>` + // in `Option<Vec<u8>>` requires us to unglue + // the trailing `>>` token. The `break_last_token` + // field is used to track this token - it gets + // appended to the captured stream when + // we evaluate a `LazyTokenStream` + break_last_token: bool, +} + +#[derive(Clone)] +struct TokenCursorFrame { + delim_sp: Option<(Delimiter, DelimSpan)>, + tree_cursor: tokenstream::Cursor, +} + +impl TokenCursorFrame { + fn new(delim_sp: Option<(Delimiter, DelimSpan)>, tts: TokenStream) -> Self { + TokenCursorFrame { delim_sp, tree_cursor: tts.into_trees() } + } +} + +impl TokenCursor { + fn next(&mut self, desugar_doc_comments: bool) -> (Token, Spacing) { + self.inlined_next(desugar_doc_comments) + } + + /// This always-inlined version should only be used on hot code paths. + #[inline(always)] + fn inlined_next(&mut self, desugar_doc_comments: bool) -> (Token, Spacing) { + loop { + // FIXME: we currently don't return `Delimiter` open/close delims. To fix #67062 we will + // need to, whereupon the `delim != Delimiter::Invisible` conditions below can be + // removed. + if let Some(tree) = self.frame.tree_cursor.next_ref() { + match tree { + &TokenTree::Token(ref token, spacing) => match (desugar_doc_comments, token) { + (true, &Token { kind: token::DocComment(_, attr_style, data), span }) => { + return self.desugar(attr_style, data, span); + } + _ => return (token.clone(), spacing), + }, + &TokenTree::Delimited(sp, delim, ref tts) => { + // Set `open_delim` to true here because we deal with it immediately. + let frame = TokenCursorFrame::new(Some((delim, sp)), tts.clone()); + self.stack.push(mem::replace(&mut self.frame, frame)); + if delim != Delimiter::Invisible { + return (Token::new(token::OpenDelim(delim), sp.open), Spacing::Alone); + } + // No open delimeter to return; continue on to the next iteration. + } + }; + } else if let Some(frame) = self.stack.pop() { + if let Some((delim, span)) = self.frame.delim_sp && delim != Delimiter::Invisible { + self.frame = frame; + return (Token::new(token::CloseDelim(delim), span.close), Spacing::Alone); + } + self.frame = frame; + // No close delimiter to return; continue on to the next iteration. + } else { + return (Token::new(token::Eof, DUMMY_SP), Spacing::Alone); + } + } + } + + fn desugar(&mut self, attr_style: AttrStyle, data: Symbol, span: Span) -> (Token, Spacing) { + // 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 data.as_str().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(span); + let body = TokenTree::Delimited( + delim_span, + Delimiter::Bracket, + [ + TokenTree::token_alone(token::Ident(sym::doc, false), span), + TokenTree::token_alone(token::Eq, span), + TokenTree::token_alone( + TokenKind::lit(token::StrRaw(num_of_hashes), data, None), + span, + ), + ] + .into_iter() + .collect::<TokenStream>(), + ); + + self.stack.push(mem::replace( + &mut self.frame, + TokenCursorFrame::new( + None, + if attr_style == AttrStyle::Inner { + [ + TokenTree::token_alone(token::Pound, span), + TokenTree::token_alone(token::Not, span), + body, + ] + .into_iter() + .collect::<TokenStream>() + } else { + [TokenTree::token_alone(token::Pound, span), body] + .into_iter() + .collect::<TokenStream>() + }, + ), + )); + + self.next(/* desugar_doc_comments */ false) + } +} + +#[derive(Debug, Clone, PartialEq)] +enum TokenType { + Token(TokenKind), + Keyword(Symbol), + Operator, + Lifetime, + Ident, + Path, + Type, + Const, +} + +impl TokenType { + fn to_string(&self) -> String { + match *self { + TokenType::Token(ref t) => format!("`{}`", pprust::token_kind_to_string(t)), + TokenType::Keyword(kw) => format!("`{}`", kw), + 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 => "a const expression".to_string(), + } + } +} + +#[derive(Copy, Clone, Debug)] +enum TokenExpectType { + Expect, + NoExpect, +} + +/// A sequence separator. +struct SeqSep { + /// The separator token. + sep: Option<TokenKind>, + /// `true` if a trailing separator is allowed. + trailing_sep_allowed: bool, +} + +impl SeqSep { + fn trailing_allowed(t: TokenKind) -> SeqSep { + SeqSep { sep: Some(t), trailing_sep_allowed: true } + } + + fn none() -> SeqSep { + SeqSep { sep: None, trailing_sep_allowed: false } + } +} + +pub enum FollowedByType { + Yes, + No, +} + +fn token_descr_opt(token: &Token) -> Option<&'static str> { + Some(match token.kind { + _ if token.is_special_ident() => "reserved identifier", + _ if token.is_used_keyword() => "keyword", + _ if token.is_unused_keyword() => "reserved keyword", + token::DocComment(..) => "doc comment", + _ => return None, + }) +} + +pub(super) fn token_descr(token: &Token) -> String { + let token_str = pprust::token_to_string(token); + match token_descr_opt(token) { + Some(prefix) => format!("{} `{}`", prefix, token_str), + _ => format!("`{}`", token_str), + } +} + +impl<'a> Parser<'a> { + pub fn new( + sess: &'a ParseSess, + tokens: TokenStream, + desugar_doc_comments: bool, + subparser_name: Option<&'static str>, + ) -> Self { + let mut parser = Parser { + sess, + token: Token::dummy(), + token_spacing: Spacing::Alone, + prev_token: Token::dummy(), + capture_cfg: false, + restrictions: Restrictions::empty(), + expected_tokens: Vec::new(), + token_cursor: TokenCursor { + frame: TokenCursorFrame::new(None, tokens), + stack: Vec::new(), + num_next_calls: 0, + desugar_doc_comments, + break_last_token: false, + }, + desugar_doc_comments, + unmatched_angle_bracket_count: 0, + max_angle_bracket_count: 0, + unclosed_delims: Vec::new(), + last_unexpected_token_span: None, + last_type_ascription: None, + subparser_name, + capture_state: CaptureState { + capturing: Capturing::No, + replace_ranges: Vec::new(), + inner_attr_ranges: Default::default(), + }, + current_closure: None, + }; + + // Make parser point to the first token. + parser.bump(); + + parser + } + + pub fn unexpected<T>(&mut self) -> PResult<'a, T> { + match self.expect_one_of(&[], &[]) { + Err(e) => Err(e), + // We can get `Ok(true)` from `recover_closing_delimiter` + // which is called in `expected_one_of_not_found`. + Ok(_) => FatalError.raise(), + } + } + + /// Expects and consumes the token `t`. Signals an error if the next token is not `t`. + pub fn expect(&mut self, t: &TokenKind) -> PResult<'a, bool /* recovered */> { + if self.expected_tokens.is_empty() { + if self.token == *t { + self.bump(); + Ok(false) + } else { + self.unexpected_try_recover(t) + } + } else { + self.expect_one_of(slice::from_ref(t), &[]) + } + } + + /// 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: &[TokenKind], + inedible: &[TokenKind], + ) -> PResult<'a, bool /* recovered */> { + if edible.contains(&self.token.kind) { + self.bump(); + Ok(false) + } else if inedible.contains(&self.token.kind) { + // leave it in the input + Ok(false) + } else if self.last_unexpected_token_span == Some(self.token.span) { + FatalError.raise(); + } else { + self.expected_one_of_not_found(edible, inedible) + } + } + + // Public for rustfmt usage. + pub fn parse_ident(&mut self) -> PResult<'a, Ident> { + self.parse_ident_common(true) + } + + fn ident_or_err(&mut self) -> PResult<'a, (Ident, /* is_raw */ bool)> { + self.token.ident().ok_or_else(|| match self.prev_token.kind { + TokenKind::DocComment(..) => { + self.span_err(self.prev_token.span, Error::UselessDocComment) + } + _ => self.expected_ident_found(), + }) + } + + fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, Ident> { + let (ident, is_raw) = self.ident_or_err()?; + if !is_raw && ident.is_reserved() { + let mut err = self.expected_ident_found(); + if recover { + err.emit(); + } else { + return Err(err); + } + } + self.bump(); + Ok(ident) + } + + /// 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. + fn check(&mut self, tok: &TokenKind) -> bool { + let is_present = self.token == *tok; + if !is_present { + self.expected_tokens.push(TokenType::Token(tok.clone())); + } + is_present + } + + fn check_noexpect(&self, tok: &TokenKind) -> bool { + self.token == *tok + } + + /// Consumes a token 'tok' if it exists. Returns whether the given token was present. + /// + /// the main purpose of this function is to reduce the cluttering of the suggestions list + /// which using the normal eat method could introduce in some cases. + pub fn eat_noexpect(&mut self, tok: &TokenKind) -> bool { + let is_present = self.check_noexpect(tok); + if is_present { + self.bump() + } + is_present + } + + /// Consumes a token 'tok' if it exists. Returns whether the given token was present. + pub fn eat(&mut self, tok: &TokenKind) -> bool { + let is_present = self.check(tok); + if is_present { + self.bump() + } + is_present + } + + /// If the next token is the given keyword, returns `true` without eating it. + /// An expectation is also added for diagnostics purposes. + fn check_keyword(&mut self, kw: Symbol) -> 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`. An expectation is also added for diagnostics purposes. + // Public for rustfmt usage. + pub fn eat_keyword(&mut self, kw: Symbol) -> bool { + if self.check_keyword(kw) { + self.bump(); + true + } else { + false + } + } + + fn eat_keyword_noexpect(&mut self, kw: Symbol) -> 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: Symbol) -> PResult<'a, ()> { + if !self.eat_keyword(kw) { self.unexpected() } else { Ok(()) } + } + + /// Is the given keyword `kw` followed by a non-reserved identifier? + fn is_kw_followed_by_ident(&self, kw: Symbol) -> bool { + self.token.is_keyword(kw) && self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident()) + } + + fn check_or_expected(&mut self, ok: bool, typ: TokenType) -> bool { + if ok { + true + } else { + self.expected_tokens.push(typ); + false + } + } + + fn check_ident(&mut self) -> bool { + self.check_or_expected(self.token.is_ident(), TokenType::Ident) + } + + fn check_path(&mut self) -> bool { + self.check_or_expected(self.token.is_path_start(), TokenType::Path) + } + + fn check_type(&mut self) -> bool { + self.check_or_expected(self.token.can_begin_type(), TokenType::Type) + } + + fn check_const_arg(&mut self) -> bool { + self.check_or_expected(self.token.can_begin_const_arg(), TokenType::Const) + } + + fn check_inline_const(&self, dist: usize) -> bool { + self.is_keyword_ahead(dist, &[kw::Const]) + && self.look_ahead(dist + 1, |t| match t.kind { + token::Interpolated(ref nt) => matches!(**nt, token::NtBlock(..)), + token::OpenDelim(Delimiter::Brace) => true, + _ => false, + }) + } + + /// Checks to see if the next token is either `+` or `+=`. + /// Otherwise returns `false`. + fn check_plus(&mut self) -> bool { + self.check_or_expected( + self.token.is_like_plus(), + TokenType::Token(token::BinOp(token::Plus)), + ) + } + + /// Eats the expected token if it's present possibly breaking + /// compound tokens like multi-character operators in process. + /// Returns `true` if the token was eaten. + fn break_and_eat(&mut self, expected: TokenKind) -> bool { + if self.token.kind == expected { + self.bump(); + return true; + } + match self.token.kind.break_two_token_op() { + Some((first, second)) if first == expected => { + let first_span = self.sess.source_map().start_point(self.token.span); + let second_span = self.token.span.with_lo(first_span.hi()); + self.token = Token::new(first, first_span); + // Keep track of this token - if we end token capturing now, + // we'll want to append this token to the captured stream. + // + // If we consume any additional tokens, then this token + // is not needed (we'll capture the entire 'glued' token), + // and `bump` will set this field to `None` + self.token_cursor.break_last_token = true; + // Use the spacing of the glued token as the spacing + // of the unglued second token. + self.bump_with((Token::new(second, second_span), self.token_spacing)); + true + } + _ => { + self.expected_tokens.push(TokenType::Token(expected)); + false + } + } + } + + /// Eats `+` possibly breaking tokens like `+=` in process. + fn eat_plus(&mut self) -> bool { + self.break_and_eat(token::BinOp(token::Plus)) + } + + /// Eats `&` possibly breaking tokens like `&&` in process. + /// Signals an error if `&` is not eaten. + fn expect_and(&mut self) -> PResult<'a, ()> { + if self.break_and_eat(token::BinOp(token::And)) { Ok(()) } else { self.unexpected() } + } + + /// Eats `|` possibly breaking tokens like `||` in process. + /// Signals an error if `|` was not eaten. + fn expect_or(&mut self) -> PResult<'a, ()> { + if self.break_and_eat(token::BinOp(token::Or)) { Ok(()) } else { self.unexpected() } + } + + /// Eats `<` possibly breaking tokens like `<<` in process. + fn eat_lt(&mut self) -> bool { + let ate = self.break_and_eat(token::Lt); + 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 + } + + /// Eats `<` possibly breaking tokens like `<<` in process. + /// Signals an error if `<` was not eaten. + fn expect_lt(&mut self) -> PResult<'a, ()> { + if self.eat_lt() { Ok(()) } else { self.unexpected() } + } + + /// Eats `>` possibly breaking tokens like `>>` in process. + /// Signals an error if `>` was not eaten. + fn expect_gt(&mut self) -> PResult<'a, ()> { + if self.break_and_eat(token::Gt) { + // 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(()) + } else { + self.unexpected() + } + } + + fn expect_any_with_type(&mut self, kets: &[&TokenKind], expect: TokenExpectType) -> bool { + kets.iter().any(|k| match expect { + TokenExpectType::Expect => self.check(k), + TokenExpectType::NoExpect => self.token == **k, + }) + } + + fn parse_seq_to_before_tokens<T>( + &mut self, + kets: &[&TokenKind], + sep: SeqSep, + expect: TokenExpectType, + mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, + ) -> PResult<'a, (Vec<T>, bool /* trailing */, bool /* recovered */)> { + let mut first = true; + let mut recovered = false; + let mut trailing = false; + let mut v = vec![]; + let unclosed_delims = !self.unclosed_delims.is_empty(); + + while !self.expect_any_with_type(kets, expect) { + if let token::CloseDelim(..) | token::Eof = self.token.kind { + break; + } + if let Some(ref t) = sep.sep { + if first { + first = false; + } else { + match self.expect(t) { + Ok(false) => { + self.current_closure.take(); + } + Ok(true) => { + self.current_closure.take(); + recovered = true; + break; + } + Err(mut expect_err) => { + let sp = self.prev_token.span.shrink_to_hi(); + let token_str = pprust::token_kind_to_string(t); + + match self.current_closure.take() { + Some(closure_spans) if self.token.kind == TokenKind::Semi => { + // Finding a semicolon instead of a comma + // after a closure body indicates that the + // closure body may be a block but the user + // forgot to put braces around its + // statements. + + self.recover_missing_braces_around_closure_body( + closure_spans, + expect_err, + )?; + + continue; + } + + _ => { + // Attempt to keep parsing if it was a similar separator. + if let Some(ref tokens) = t.similar_tokens() { + if tokens.contains(&self.token.kind) && !unclosed_delims { + self.bump(); + } + } + } + } + + // If this was a missing `@` in a binding pattern + // bail with a suggestion + // https://github.com/rust-lang/rust/issues/72373 + if self.prev_token.is_ident() && self.token.kind == token::DotDot { + let msg = format!( + "if you meant to bind the contents of \ + the rest of the array pattern into `{}`, use `@`", + pprust::token_to_string(&self.prev_token) + ); + expect_err + .span_suggestion_verbose( + self.prev_token.span.shrink_to_hi().until(self.token.span), + &msg, + " @ ", + Applicability::MaybeIncorrect, + ) + .emit(); + break; + } + + // Attempt to keep parsing if it was an omitted separator. + match f(self) { + Ok(t) => { + // Parsed successfully, therefore most probably the code only + // misses a separator. + expect_err + .span_suggestion_short( + sp, + &format!("missing `{}`", token_str), + token_str, + Applicability::MaybeIncorrect, + ) + .emit(); + + v.push(t); + continue; + } + Err(e) => { + // Parsing failed, therefore it must be something more serious + // than just a missing separator. + expect_err.emit(); + + e.cancel(); + break; + } + } + } + } + } + } + if sep.trailing_sep_allowed && self.expect_any_with_type(kets, expect) { + trailing = true; + break; + } + + let t = f(self)?; + v.push(t); + } + + Ok((v, trailing, recovered)) + } + + fn recover_missing_braces_around_closure_body( + &mut self, + closure_spans: ClosureSpans, + mut expect_err: DiagnosticBuilder<'_, ErrorGuaranteed>, + ) -> PResult<'a, ()> { + let initial_semicolon = self.token.span; + + while self.eat(&TokenKind::Semi) { + let _ = self.parse_stmt(ForceCollect::Yes)?; + } + + expect_err.set_primary_message( + "closure bodies that contain statements must be surrounded by braces", + ); + + let preceding_pipe_span = closure_spans.closing_pipe; + let following_token_span = self.token.span; + + let mut first_note = MultiSpan::from(vec![initial_semicolon]); + first_note.push_span_label( + initial_semicolon, + "this `;` turns the preceding closure into a statement", + ); + first_note.push_span_label( + closure_spans.body, + "this expression is a statement because of the trailing semicolon", + ); + expect_err.span_note(first_note, "statement found outside of a block"); + + let mut second_note = MultiSpan::from(vec![closure_spans.whole_closure]); + second_note.push_span_label(closure_spans.whole_closure, "this is the parsed closure..."); + second_note.push_span_label( + following_token_span, + "...but likely you meant the closure to end here", + ); + expect_err.span_note(second_note, "the closure body may be incorrectly delimited"); + + expect_err.set_span(vec![preceding_pipe_span, following_token_span]); + + let opening_suggestion_str = " {".to_string(); + let closing_suggestion_str = "}".to_string(); + + expect_err.multipart_suggestion( + "try adding braces", + vec![ + (preceding_pipe_span.shrink_to_hi(), opening_suggestion_str), + (following_token_span.shrink_to_lo(), closing_suggestion_str), + ], + Applicability::MaybeIncorrect, + ); + + expect_err.emit(); + + Ok(()) + } + + /// Parses a sequence, not including the closing delimiter. The function + /// `f` must consume tokens until reaching the next separator or + /// closing bracket. + fn parse_seq_to_before_end<T>( + &mut self, + ket: &TokenKind, + sep: SeqSep, + f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, + ) -> PResult<'a, (Vec<T>, bool, bool)> { + self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f) + } + + /// Parses a sequence, including the closing delimiter. The function + /// `f` must consume tokens until reaching the next separator or + /// closing bracket. + fn parse_seq_to_end<T>( + &mut self, + ket: &TokenKind, + sep: SeqSep, + f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, + ) -> PResult<'a, (Vec<T>, bool /* trailing */)> { + let (val, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?; + if !recovered { + self.eat(ket); + } + Ok((val, trailing)) + } + + /// 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>( + &mut self, + bra: &TokenKind, + ket: &TokenKind, + sep: SeqSep, + f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, + ) -> PResult<'a, (Vec<T>, bool)> { + self.expect(bra)?; + self.parse_seq_to_end(ket, sep, f) + } + + fn parse_delim_comma_seq<T>( + &mut self, + delim: Delimiter, + f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, + ) -> PResult<'a, (Vec<T>, bool)> { + self.parse_unspanned_seq( + &token::OpenDelim(delim), + &token::CloseDelim(delim), + SeqSep::trailing_allowed(token::Comma), + f, + ) + } + + fn parse_paren_comma_seq<T>( + &mut self, + f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, + ) -> PResult<'a, (Vec<T>, bool)> { + self.parse_delim_comma_seq(Delimiter::Parenthesis, f) + } + + /// Advance the parser by one token using provided token as the next one. + fn bump_with(&mut self, next: (Token, Spacing)) { + self.inlined_bump_with(next) + } + + /// This always-inlined version should only be used on hot code paths. + #[inline(always)] + fn inlined_bump_with(&mut self, (next_token, next_spacing): (Token, Spacing)) { + // Update the current and previous tokens. + self.prev_token = mem::replace(&mut self.token, next_token); + self.token_spacing = next_spacing; + + // Diagnostics. + self.expected_tokens.clear(); + } + + /// Advance the parser by one token. + pub fn bump(&mut self) { + // Note: destructuring here would give nicer code, but it was found in #96210 to be slower + // than `.0`/`.1` access. + let mut next = self.token_cursor.inlined_next(self.desugar_doc_comments); + self.token_cursor.num_next_calls += 1; + // We've retrieved an token from the underlying + // cursor, so we no longer need to worry about + // an unglued token. See `break_and_eat` for more details + self.token_cursor.break_last_token = false; + if next.0.span.is_dummy() { + // Tweak the location for better diagnostics, but keep syntactic context intact. + let fallback_span = self.token.span; + next.0.span = fallback_span.with_ctxt(next.0.span.ctxt()); + } + debug_assert!(!matches!( + next.0.kind, + token::OpenDelim(Delimiter::Invisible) | token::CloseDelim(Delimiter::Invisible) + )); + self.inlined_bump_with(next) + } + + /// Look-ahead `dist` tokens of `self.token` and get access to that token there. + /// When `dist == 0` then the current token is looked at. + pub fn look_ahead<R>(&self, dist: usize, looker: impl FnOnce(&Token) -> R) -> R { + if dist == 0 { + return looker(&self.token); + } + + let frame = &self.token_cursor.frame; + if let Some((delim, span)) = frame.delim_sp && delim != Delimiter::Invisible { + let all_normal = (0..dist).all(|i| { + let token = frame.tree_cursor.look_ahead(i); + !matches!(token, Some(TokenTree::Delimited(_, Delimiter::Invisible, _))) + }); + if all_normal { + return match frame.tree_cursor.look_ahead(dist - 1) { + Some(tree) => match tree { + TokenTree::Token(token, _) => looker(token), + TokenTree::Delimited(dspan, delim, _) => { + looker(&Token::new(token::OpenDelim(*delim), dspan.open)) + } + }, + None => looker(&Token::new(token::CloseDelim(delim), span.close)), + }; + } + } + + let mut cursor = self.token_cursor.clone(); + let mut i = 0; + let mut token = Token::dummy(); + while i < dist { + token = cursor.next(/* desugar_doc_comments */ false).0; + if matches!( + token.kind, + token::OpenDelim(Delimiter::Invisible) | token::CloseDelim(Delimiter::Invisible) + ) { + continue; + } + i += 1; + } + return looker(&token); + } + + /// Returns whether any of the given keywords are `dist` tokens ahead of the current one. + fn is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool { + self.look_ahead(dist, |t| kws.iter().any(|&kw| t.is_keyword(kw))) + } + + /// Parses asyncness: `async` or nothing. + fn parse_asyncness(&mut self) -> Async { + if self.eat_keyword(kw::Async) { + let span = self.prev_token.uninterpolated_span(); + Async::Yes { span, closure_id: DUMMY_NODE_ID, return_impl_trait_id: DUMMY_NODE_ID } + } else { + Async::No + } + } + + /// Parses unsafety: `unsafe` or nothing. + fn parse_unsafety(&mut self) -> Unsafe { + if self.eat_keyword(kw::Unsafe) { + Unsafe::Yes(self.prev_token.uninterpolated_span()) + } else { + Unsafe::No + } + } + + /// Parses constness: `const` or nothing. + fn parse_constness(&mut self) -> Const { + // Avoid const blocks to be parsed as const items + if self.look_ahead(1, |t| t != &token::OpenDelim(Delimiter::Brace)) + && self.eat_keyword(kw::Const) + { + Const::Yes(self.prev_token.uninterpolated_span()) + } else { + Const::No + } + } + + /// Parses inline const expressions. + fn parse_const_block(&mut self, span: Span, pat: bool) -> PResult<'a, P<Expr>> { + if pat { + self.sess.gated_spans.gate(sym::inline_const_pat, span); + } else { + self.sess.gated_spans.gate(sym::inline_const, span); + } + self.eat_keyword(kw::Const); + let (attrs, blk) = self.parse_inner_attrs_and_block()?; + let anon_const = AnonConst { + id: DUMMY_NODE_ID, + value: self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new()), + }; + let blk_span = anon_const.value.span; + Ok(self.mk_expr(span.to(blk_span), ExprKind::ConstBlock(anon_const), AttrVec::from(attrs))) + } + + /// Parses mutability (`mut` or nothing). + fn parse_mutability(&mut self) -> Mutability { + if self.eat_keyword(kw::Mut) { Mutability::Mut } else { Mutability::Not } + } + + /// Possibly parses mutability (`const` or `mut`). + fn parse_const_or_mut(&mut self) -> Option<Mutability> { + if self.eat_keyword(kw::Mut) { + Some(Mutability::Mut) + } else if self.eat_keyword(kw::Const) { + Some(Mutability::Not) + } else { + None + } + } + + fn parse_field_name(&mut self) -> PResult<'a, Ident> { + if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) = self.token.kind + { + self.expect_no_suffix(self.token.span, "a tuple index", suffix); + self.bump(); + Ok(Ident::new(symbol, self.prev_token.span)) + } else { + self.parse_ident_common(true) + } + } + + fn parse_mac_args(&mut self) -> PResult<'a, P<MacArgs>> { + self.parse_mac_args_common(true).map(P) + } + + fn parse_attr_args(&mut self) -> PResult<'a, MacArgs> { + self.parse_mac_args_common(false) + } + + fn parse_mac_args_common(&mut self, delimited_only: bool) -> PResult<'a, MacArgs> { + Ok( + if self.check(&token::OpenDelim(Delimiter::Parenthesis)) + || self.check(&token::OpenDelim(Delimiter::Bracket)) + || self.check(&token::OpenDelim(Delimiter::Brace)) + { + match self.parse_token_tree() { + TokenTree::Delimited(dspan, delim, tokens) => + // We've confirmed above that there is a delimiter so unwrapping is OK. + { + MacArgs::Delimited(dspan, MacDelimiter::from_token(delim).unwrap(), tokens) + } + _ => unreachable!(), + } + } else if !delimited_only { + if self.eat(&token::Eq) { + let eq_span = self.prev_token.span; + MacArgs::Eq(eq_span, MacArgsEq::Ast(self.parse_expr_force_collect()?)) + } else { + MacArgs::Empty + } + } else { + return self.unexpected(); + }, + ) + } + + fn parse_or_use_outer_attributes( + &mut self, + already_parsed_attrs: Option<AttrWrapper>, + ) -> PResult<'a, AttrWrapper> { + if let Some(attrs) = already_parsed_attrs { + Ok(attrs) + } else { + self.parse_outer_attributes() + } + } + + /// Parses a single token tree from the input. + pub(crate) fn parse_token_tree(&mut self) -> TokenTree { + match self.token.kind { + token::OpenDelim(..) => { + // Grab the tokens from this frame. + let frame = &self.token_cursor.frame; + let stream = frame.tree_cursor.stream.clone(); + let (delim, span) = frame.delim_sp.unwrap(); + + // Advance the token cursor through the entire delimited + // sequence. After getting the `OpenDelim` we are *within* the + // delimited sequence, i.e. at depth `d`. After getting the + // matching `CloseDelim` we are *after* the delimited sequence, + // i.e. at depth `d - 1`. + let target_depth = self.token_cursor.stack.len() - 1; + loop { + // Advance one token at a time, so `TokenCursor::next()` + // can capture these tokens if necessary. + self.bump(); + if self.token_cursor.stack.len() == target_depth { + debug_assert!(matches!(self.token.kind, token::CloseDelim(_))); + break; + } + } + + // Consume close delimiter + self.bump(); + TokenTree::Delimited(span, delim, stream) + } + token::CloseDelim(_) | token::Eof => unreachable!(), + _ => { + self.bump(); + TokenTree::Token(self.prev_token.clone(), Spacing::Alone) + } + } + } + + /// Parses 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.kind { + token::Eof | token::CloseDelim(..) => break, + _ => result.push(self.parse_token_tree()), + } + } + TokenStream::new(result) + } + + /// Evaluates the closure with restrictions in place. + /// + /// Afters the closure is evaluated, restrictions are reset. + fn with_res<T>(&mut self, res: Restrictions, f: impl FnOnce(&mut Self) -> T) -> T { + let old = self.restrictions; + self.restrictions = res; + let res = f(self); + self.restrictions = old; + res + } + + /// Parses `pub` and `pub(in path)` plus shortcuts `pub(crate)` for `pub(in 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 aren't valid, + /// so emit a proper diagnostic. + // Public for rustfmt usage. + pub fn parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility> { + maybe_whole!(self, NtVis, |x| x.into_inner()); + + if !self.eat_keyword(kw::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(Visibility { + span: self.token.span.shrink_to_lo(), + kind: VisibilityKind::Inherited, + tokens: None, + }); + } + let lo = self.prev_token.span; + + if self.check(&token::OpenDelim(Delimiter::Parenthesis)) { + // 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.is_keyword_ahead(1, &[kw::In]) { + // Parse `pub(in path)`. + self.bump(); // `(` + self.bump(); // `in` + let path = self.parse_path(PathStyle::Mod)?; // `path` + self.expect(&token::CloseDelim(Delimiter::Parenthesis))?; // `)` + let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID }; + return Ok(Visibility { + span: lo.to(self.prev_token.span), + kind: vis, + tokens: None, + }); + } else if self.look_ahead(2, |t| t == &token::CloseDelim(Delimiter::Parenthesis)) + && self.is_keyword_ahead(1, &[kw::Crate, kw::Super, kw::SelfLower]) + { + // Parse `pub(crate)`, `pub(self)`, or `pub(super)`. + self.bump(); // `(` + let path = self.parse_path(PathStyle::Mod)?; // `crate`/`super`/`self` + self.expect(&token::CloseDelim(Delimiter::Parenthesis))?; // `)` + let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID }; + return Ok(Visibility { + span: lo.to(self.prev_token.span), + kind: vis, + tokens: None, + }); + } else if let FollowedByType::No = fbt { + // Provide this diagnostic if a type cannot follow; + // in particular, if this is not a tuple struct. + self.recover_incorrect_vis_restriction()?; + // Emit diagnostic, but continue with public visibility. + } + } + + Ok(Visibility { span: lo, kind: VisibilityKind::Public, tokens: None }) + } + + /// Recovery for e.g. `pub(something) fn ...` or `struct X { pub(something) y: Z }` + fn recover_incorrect_vis_restriction(&mut self) -> PResult<'a, ()> { + self.bump(); // `(` + let path = self.parse_path(PathStyle::Mod)?; + self.expect(&token::CloseDelim(Delimiter::Parenthesis))?; // `)` + + 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_str = pprust::path_to_string(&path); + + struct_span_err!(self.sess.span_diagnostic, path.span, E0704, "{}", msg) + .help(suggestion) + .span_suggestion( + path.span, + &format!("make this visible only to module `{}` with `in`", path_str), + format!("in {}", path_str), + Applicability::MachineApplicable, + ) + .emit(); + + Ok(()) + } + + /// Parses `extern string_literal?`. + fn parse_extern(&mut self) -> Extern { + if self.eat_keyword(kw::Extern) { + let mut extern_span = self.prev_token.span; + let abi = self.parse_abi(); + if let Some(abi) = abi { + extern_span = extern_span.to(abi.span); + } + Extern::from_abi(abi, extern_span) + } else { + Extern::None + } + } + + /// Parses a string literal as an ABI spec. + fn parse_abi(&mut self) -> Option<StrLit> { + match self.parse_str_lit() { + Ok(str_lit) => Some(str_lit), + Err(Some(lit)) => match lit.kind { + ast::LitKind::Err(_) => None, + _ => { + self.struct_span_err(lit.span, "non-string ABI literal") + .span_suggestion( + lit.span, + "specify the ABI with a string literal", + "\"C\"", + Applicability::MaybeIncorrect, + ) + .emit(); + None + } + }, + Err(None) => None, + } + } + + pub fn collect_tokens_no_attrs<R: HasAttrs + HasTokens>( + &mut self, + f: impl FnOnce(&mut Self) -> PResult<'a, R>, + ) -> PResult<'a, R> { + // The only reason to call `collect_tokens_no_attrs` is if you want tokens, so use + // `ForceCollect::Yes` + self.collect_tokens_trailing_token( + AttrWrapper::empty(), + ForceCollect::Yes, + |this, _attrs| Ok((f(this)?, TrailingToken::None)), + ) + } + + /// `::{` or `::*` + fn is_import_coupler(&mut self) -> bool { + self.check(&token::ModSep) + && self.look_ahead(1, |t| { + *t == token::OpenDelim(Delimiter::Brace) || *t == token::BinOp(token::Star) + }) + } + + pub fn clear_expected_tokens(&mut self) { + self.expected_tokens.clear(); + } +} + +pub(crate) fn make_unclosed_delims_error( + unmatched: UnmatchedBrace, + sess: &ParseSess, +) -> Option<DiagnosticBuilder<'_, ErrorGuaranteed>> { + // `None` here means an `Eof` was found. We already emit those errors elsewhere, we add them to + // `unmatched_braces` only for error recovery in the `Parser`. + let found_delim = unmatched.found_delim?; + let span: MultiSpan = if let Some(sp) = unmatched.unclosed_span { + vec![unmatched.found_span, sp].into() + } else { + unmatched.found_span.into() + }; + let mut err = sess.span_diagnostic.struct_span_err( + span, + &format!( + "mismatched closing delimiter: `{}`", + pprust::token_kind_to_string(&token::CloseDelim(found_delim)), + ), + ); + err.span_label(unmatched.found_span, "mismatched closing delimiter"); + if let Some(sp) = unmatched.candidate_span { + err.span_label(sp, "closing delimiter possibly meant for this"); + } + if let Some(sp) = unmatched.unclosed_span { + err.span_label(sp, "unclosed delimiter"); + } + Some(err) +} + +pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &ParseSess) { + *sess.reached_eof.borrow_mut() |= + unclosed_delims.iter().any(|unmatched_delim| unmatched_delim.found_delim.is_none()); + for unmatched in unclosed_delims.drain(..) { + if let Some(mut e) = make_unclosed_delims_error(unmatched, sess) { + e.emit(); + } + } +} + +/// A helper struct used when building an `AttrAnnotatedTokenStream` from +/// a `LazyTokenStream`. Both delimiter and non-delimited tokens +/// are stored as `FlatToken::Token`. A vector of `FlatToken`s +/// is then 'parsed' to build up an `AttrAnnotatedTokenStream` with nested +/// `AttrAnnotatedTokenTree::Delimited` tokens +#[derive(Debug, Clone)] +pub enum FlatToken { + /// A token - this holds both delimiter (e.g. '{' and '}') + /// and non-delimiter tokens + Token(Token), + /// Holds the `AttributesData` for an AST node. The + /// `AttributesData` is inserted directly into the + /// constructed `AttrAnnotatedTokenStream` as + /// an `AttrAnnotatedTokenTree::Attributes` + AttrTarget(AttributesData), + /// A special 'empty' token that is ignored during the conversion + /// to an `AttrAnnotatedTokenStream`. This is used to simplify the + /// handling of replace ranges. + Empty, +} + +#[derive(Debug)] +pub enum NtOrTt { + Nt(Nonterminal), + Tt(TokenTree), +} |