bjoernager/rust
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rust/src/libsyntax/parse/parser.rs
Mazdak Farrokhzad 3dbfbafe3e parser: split into {ty, path}.rs
2019-08-11 19:59:27 +02:00

2487 lines
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Rust
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mod expr;
use expr::LhsExpr;
mod pat;
mod item;
pub use item::AliasKind;
mod module;
pub use module::{ModulePath, ModulePathSuccess};
mod ty;
mod path;
pub use path::PathStyle;
use crate::ast::{self, AttrStyle};
use crate::ast::{Arg, Attribute, BindingMode};
use crate::ast::{Block, BlockCheckMode, Expr, ExprKind, Stmt, StmtKind};
use crate::ast::{FnDecl};
use crate::ast::{Ident, IsAsync, Local, Lifetime};
use crate::ast::{MacStmtStyle, Mac_, MacDelimiter};
use crate::ast::{Mutability};
use crate::ast::StrStyle;
use crate::ast::SelfKind;
use crate::ast::{GenericParam, GenericParamKind, WhereClause};
use crate::ast::{Ty, TyKind, GenericBounds};
use crate::ast::{Visibility, VisibilityKind, Unsafety, CrateSugar};
use crate::ext::base::DummyResult;
use crate::ext::hygiene::SyntaxContext;
use crate::source_map::{self, respan};
use crate::parse::{SeqSep, classify, literal, token};
use crate::parse::lexer::UnmatchedBrace;
use crate::parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
use crate::parse::token::{Token, TokenKind, DelimToken};
use crate::parse::{ParseSess, Directory, DirectoryOwnership};
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::{kw, sym, Symbol};
use crate::parse::diagnostics::{Error, dummy_arg};
use errors::{Applicability, DiagnosticId, FatalError};
use rustc_target::spec::abi::{self, Abi};
use syntax_pos::{Span, BytePos, DUMMY_SP, FileName};
use log::debug;
use std::borrow::Cow;
use std::{cmp, mem, slice};
use std::path::PathBuf;
bitflags::bitflags! {
struct Restrictions: u8 {
const STMT_EXPR = 1 << 0;
const NO_STRUCT_LITERAL = 1 << 1;
}
}
#[derive(Clone, Copy, PartialEq, Debug)]
crate enum SemiColonMode {
Break,
Ignore,
Comma,
}
#[derive(Clone, Copy, PartialEq, Debug)]
crate enum BlockMode {
Break,
Ignore,
}
/// As 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 && $self.look_ahead(1, |t| t == &token::ModSep) {
if let token::Interpolated(nt) = &$self.token.kind {
if let token::NtTy(ty) = &**nt {
let ty = ty.clone();
$self.bump();
return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_span, ty);
}
}
}
}
}
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,
BitOr,
Other,
}
// NOTE: `Ident`s are handled by `common.rs`.
#[derive(Clone)]
pub struct Parser<'a> {
pub sess: &'a ParseSess,
/// The current normalized token.
/// "Normalized" means that some interpolated tokens
/// (`$i: ident` and `$l: lifetime` meta-variables) are replaced
/// with non-interpolated identifier and lifetime tokens they refer to.
/// Perhaps the normalized / non-normalized setup can be simplified somehow.
pub token: Token,
/// Span of the current non-normalized token.
meta_var_span: Option<Span>,
/// Span of the previous non-normalized token.
pub prev_span: Span,
/// Kind of the previous normalized token (in simplified form).
prev_token_kind: PrevTokenKind,
restrictions: Restrictions,
/// Used to determine the path to externally loaded source files.
crate directory: Directory<'a>,
/// `true` 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>,
crate token_cursor: TokenCursor,
desugar_doc_comments: bool,
/// `true` 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>,
crate last_unexpected_token_span: Option<Span>,
crate last_type_ascription: Option<(Span, bool /* likely path typo */)>,
/// If present, this `Parser` is not parsing Rust code but rather a macro call.
crate subparser_name: Option<&'static str>,
}
impl<'a> Drop for Parser<'a> {
fn drop(&mut self) {
let diag = self.diagnostic();
emit_unclosed_delims(&mut self.unclosed_delims, diag);
}
}
#[derive(Clone)]
crate struct TokenCursor {
crate frame: TokenCursorFrame,
crate stack: Vec<TokenCursorFrame>,
}
#[derive(Clone)]
crate struct TokenCursorFrame {
crate delim: token::DelimToken,
crate span: DelimSpan,
crate open_delim: bool,
crate tree_cursor: tokenstream::Cursor,
crate close_delim: bool,
crate 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)]
crate enum LastToken {
Collecting(Vec<TreeAndJoint>),
Was(Option<TreeAndJoint>),
}
impl TokenCursorFrame {
fn new(span: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
TokenCursorFrame {
delim,
span,
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) -> Token {
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 Token::new(token::Eof, 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(token) => return token,
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) -> Token {
let (name, sp) = match self.next() {
Token { kind: token::DocComment(name), span } => (name, span),
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(token::Ident(sym::doc, false), sp),
TokenTree::token(token::Eq, sp),
TokenTree::token(TokenKind::lit(
token::StrRaw(num_of_hashes), Symbol::intern(&stripped), None
), sp),
]
.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(token::Pound, sp), TokenTree::token(token::Not, sp), body]
.iter().cloned().collect::<TokenStream>().into()
} else {
[TokenTree::token(token::Pound, sp), body]
.iter().cloned().collect::<TokenStream>().into()
},
)));
self.next()
}
}
#[derive(Clone, PartialEq)]
crate enum TokenType {
Token(TokenKind),
Keyword(Symbol),
Operator,
Lifetime,
Ident,
Path,
Type,
Const,
}
impl TokenType {
crate 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 => "const".to_string(),
}
}
}
#[derive(Copy, Clone, Debug)]
crate 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,
subparser_name: Option<&'static str>,
) -> Self {
let mut parser = Parser {
sess,
token: Token::dummy(),
prev_span: 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(),
last_unexpected_token_span: None,
last_type_ascription: None,
subparser_name,
};
parser.token = parser.next_tok();
if let Some(directory) = directory {
parser.directory = directory;
} else if !parser.token.span.is_dummy() {
if let FileName::Real(mut path) =
sess.source_map().span_to_unmapped_path(parser.token.span) {
path.pop();
parser.directory.path = Cow::from(path);
}
}
parser.process_potential_macro_variable();
parser
}
fn next_tok(&mut self) -> Token {
let mut next = if self.desugar_doc_comments {
self.token_cursor.next_desugared()
} else {
self.token_cursor.next()
};
if next.span.is_dummy() {
// Tweak the location for better diagnostics, but keep syntactic context intact.
next.span = self.prev_span.with_ctxt(next.span.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)
}
crate fn token_descr(&self) -> Option<&'static str> {
Some(match &self.token.kind {
_ if self.token.is_special_ident() => "reserved identifier",
_ if self.token.is_used_keyword() => "keyword",
_ if self.token.is_unused_keyword() => "reserved keyword",
token::DocComment(..) => "doc comment",
_ => return None,
})
}
crate 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())
}
}
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: &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)
}
}
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.kind {
token::Ident(name, _) => {
if self.token.is_reserved_ident() {
let mut err = self.expected_ident_found();
if recover {
err.emit();
} else {
return Err(err);
}
}
let span = self.token.span;
self.bump();
Ok(Ident::new(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: &TokenKind) -> 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: &TokenKind) -> bool {
let is_present = self.check(tok);
if is_present { self.bump() }
is_present
}
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`.
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(())
}
}
crate 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.kind {
token::BinOp(token::Plus) => {
self.bump();
true
}
token::BinOpEq(token::Plus) => {
let span = self.token.span.with_lo(self.token.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.kind {
token::BinOp(token::And) => {
self.bump();
Ok(())
}
token::AndAnd => {
let span = self.token.span.with_lo(self.token.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.kind {
token::BinOp(token::Or) => {
self.bump();
Ok(())
}
token::OrOr => {
let span = self.token.span.with_lo(self.token.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>) {
literal::expect_no_suffix(&self.sess.span_diagnostic, sp, kind, suffix)
}
/// 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.kind {
token::Lt => {
self.bump();
true
}
token::BinOp(token::Shl) => {
let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
self.bump_with(token::Lt, span);
true
}
token::LArrow => {
let span = self.token.span.with_lo(self.token.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.kind {
token::Gt => {
self.bump();
Some(())
}
token::BinOp(token::Shr) => {
let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
Some(self.bump_with(token::Gt, span))
}
token::BinOpEq(token::Shr) => {
let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
Some(self.bump_with(token::Ge, span))
}
token::Ge => {
let span = self.token.span.with_lo(self.token.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(),
}
}
/// 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>(
&mut self,
ket: &TokenKind,
sep: SeqSep,
f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
) -> PResult<'a, Vec<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>(
&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)
}
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,
}
})
}
crate 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![];
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) => {}
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.kind) {
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 && self.expect_any_with_type(kets, expect) {
trailing = true;
break;
}
let t = f(self)?;
v.push(t);
}
Ok((v, trailing, 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>(
&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)?;
let (result, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
if !recovered {
self.eat(ket);
}
Ok((result, trailing))
}
fn parse_delim_comma_seq<T>(
&mut self,
delim: DelimToken,
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(token::Paren, f)
}
/// 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.token.span);
// Record last token kind for possible error recovery.
self.prev_token_kind = match self.token.kind {
token::DocComment(..) => PrevTokenKind::DocComment,
token::Comma => PrevTokenKind::Comma,
token::BinOp(token::Plus) => PrevTokenKind::Plus,
token::BinOp(token::Or) => PrevTokenKind::BitOr,
token::Interpolated(..) => PrevTokenKind::Interpolated,
token::Eof => PrevTokenKind::Eof,
token::Ident(..) => PrevTokenKind::Ident,
_ => PrevTokenKind::Other,
};
self.token = self.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: TokenKind, span: Span) {
self.prev_span = self.token.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.token = Token::new(next, span);
self.expected_tokens.clear();
}
pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where
F: FnOnce(&Token) -> R,
{
if dist == 0 {
return f(&self.token);
}
let frame = &self.token_cursor.frame;
f(&match frame.tree_cursor.look_ahead(dist - 1) {
Some(tree) => match tree {
TokenTree::Token(token) => token,
TokenTree::Delimited(dspan, delim, _) =>
Token::new(token::OpenDelim(delim), dspan.open),
}
None => Token::new(token::CloseDelim(frame.delim), frame.span.close)
})
}
/// 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) -> IsAsync {
if self.eat_keyword(kw::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(kw::Unsafe) {
Unsafety::Unsafe
} else {
Unsafety::Normal
}
}
fn is_named_argument(&self) -> bool {
let offset = match self.token.kind {
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(kw::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.
/// This version of parse arg doesn't necessarily require identifier names.
fn parse_arg_general<F>(
&mut self,
is_trait_item: bool,
allow_c_variadic: bool,
is_name_required: F,
) -> PResult<'a, Arg>
where
F: Fn(&token::Token) -> bool
{
let lo = self.token.span;
let attrs = self.parse_arg_attributes()?;
if let Some(mut arg) = self.parse_self_arg()? {
arg.attrs = attrs.into();
return self.recover_bad_self_arg(arg, is_trait_item);
}
let is_name_required = is_name_required(&self.token);
let (pat, ty) = if is_name_required || self.is_named_argument() {
debug!("parse_arg_general parse_pat (is_name_required:{})", is_name_required);
let pat = self.parse_pat(Some("argument name"))?;
if let Err(mut err) = self.expect(&token::Colon) {
if let Some(ident) = self.argument_without_type(
&mut err,
pat,
is_name_required,
is_trait_item,
) {
err.emit();
return Ok(dummy_arg(ident));
} else {
return Err(err);
}
}
self.eat_incorrect_doc_comment_for_arg_type();
(pat, self.parse_ty_common(true, true, allow_c_variadic)?)
} else {
debug!("parse_arg_general ident_to_pat");
let parser_snapshot_before_ty = self.clone();
self.eat_incorrect_doc_comment_for_arg_type();
let mut ty = self.parse_ty_common(true, true, allow_c_variadic);
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(kw::Invalid, self.prev_span);
let bm = BindingMode::ByValue(Mutability::Immutable);
let pat = self.mk_pat_ident(ty.span, bm, ident);
(pat, ty)
}
Err(mut err) => {
// If this is a C-variadic argument and we hit an error, return the
// error.
if self.token == token::DotDotDot {
return Err(err);
}
// Recover from attempting to parse the argument as a type without pattern.
err.cancel();
mem::replace(self, parser_snapshot_before_ty);
self.recover_arg_parse()?
}
}
};
let span = lo.to(self.token.span);
Ok(Arg { attrs: attrs.into(), id: ast::DUMMY_NODE_ID, pat, span, ty })
}
/// Parses an argument in a lambda header (e.g., `|arg, arg|`).
fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
let lo = self.token.span;
let attrs = self.parse_arg_attributes()?;
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,
})
};
let span = lo.to(self.token.span);
Ok(Arg {
attrs: attrs.into(),
ty: t,
pat,
span,
id: ast::DUMMY_NODE_ID
})
}
fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
match self.token.kind {
token::Ident(name, false) if name == kw::Underscore => {
let span = self.token.span;
self.bump();
Ok(Ident::new(name, span))
}
_ => self.parse_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.token.span;
self.bump();
Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
} else {
self.span_bug(self.token.span, "not a lifetime")
}
}
/// Parses mutability (`mut` or nothing).
fn parse_mutability(&mut self) -> Mutability {
if self.eat_keyword(kw::Mut) {
Mutability::Mutable
} else {
Mutability::Immutable
}
}
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_span))
} else {
self.parse_ident_common(false)
}
}
fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, TokenStream)> {
let delim = match self.token.kind {
token::OpenDelim(delim) => delim,
_ => {
let msg = "expected open delimiter";
let mut err = self.fatal(msg);
err.span_label(self.token.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()))
}
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())
}
}
crate fn process_potential_macro_variable(&mut self) {
self.token = match self.token.kind {
token::Dollar if self.token.span.ctxt() != SyntaxContext::empty() &&
self.look_ahead(1, |t| t.is_ident()) => {
self.bump();
let name = match self.token.kind {
token::Ident(name, _) => name,
_ => unreachable!()
};
let span = self.prev_span.to(self.token.span);
self.diagnostic()
.struct_span_fatal(span, &format!("unknown macro variable `{}`", name))
.span_label(span, "unknown macro variable")
.emit();
self.bump();
return
}
token::Interpolated(ref nt) => {
self.meta_var_span = Some(self.token.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::new(token::Ident(ident.name, is_raw), ident.span),
token::NtLifetime(ident) =>
Token::new(token::Lifetime(ident.name), ident.span),
_ => return,
}
}
_ => return,
};
}
/// Parses a single token tree from the input.
crate fn parse_token_tree(&mut self) -> TokenTree {
match self.token.kind {
token::OpenDelim(..) => {
let frame = mem::replace(&mut self.token_cursor.frame,
self.token_cursor.stack.pop().unwrap());
self.token.span = frame.span.entire();
self.bump();
TokenTree::Delimited(
frame.span,
frame.delim,
frame.tree_cursor.stream.into(),
)
},
token::CloseDelim(_) | token::Eof => unreachable!(),
_ => {
let token = self.token.take();
self.bump();
TokenTree::Token(token)
}
}
}
/// 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().into()),
}
}
TokenStream::new(result)
}
/// 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 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 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.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.token.span
} else {
self.prev_span
};
Ok(P(ast::Local {
ty,
pat,
init,
id: ast::DUMMY_NODE_ID,
span: lo.to(hi),
attrs,
}))
}
/// 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))
}
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_fn(&self) -> bool {
self.token.is_keyword(kw::Async) &&
self.is_keyword_ahead(1, &[kw::Fn])
}
fn is_crate_vis(&self) -> bool {
self.token.is_keyword(kw::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
}
fn is_auto_trait_item(&self) -> bool {
// auto trait
(self.token.is_keyword(kw::Auto) &&
self.is_keyword_ahead(1, &[kw::Trait]))
|| // unsafe auto trait
(self.token.is_keyword(kw::Unsafe) &&
self.is_keyword_ahead(1, &[kw::Auto]) &&
self.is_keyword_ahead(2, &[kw::Trait]))
}
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.token.span;
Ok(Some(if self.eat_keyword(kw::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_auto_trait_item() &&
!self.is_async_fn() {
let path = self.parse_path(PathStyle::Expr)?;
if !self.eat(&token::Not) {
let expr = if self.check(&token::OpenDelim(token::Brace)) {
self.parse_struct_expr(lo, path, ThinVec::new())?
} else {
let hi = self.prev_span;
self.mk_expr(lo.to(hi), ExprKind::Path(None, path), 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),
}));
}
let (delim, tts) = self.expect_delimited_token_tree()?;
let hi = self.prev_span;
let style = if delim == MacDelimiter::Brace {
MacStmtStyle::Braces
} else {
MacStmtStyle::NoBraces
};
let mac = respan(lo.to(hi), Mac_ {
path,
tts,
delim,
prior_type_ascription: self.last_type_ascription,
});
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.kind {
// 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_expr(mac.span, ExprKind::Mac(mac), ThinVec::new());
let e = self.maybe_recover_from_bad_qpath(e, true)?;
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 {
// 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.token.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),
}
}
}
}))
}
/// 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.token.span;
if !self.eat(&token::OpenDelim(token::Brace)) {
let sp = self.token.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(kw::In) || self.token == token::Colon;
if self.token.is_ident_named(sym::and) {
e.span_suggestion_short(
self.token.span,
"use `&&` instead of `and` for the boolean operator",
"&&".to_string(),
Applicability::MaybeIncorrect,
);
}
if self.token.is_ident_named(sym::or) {
e.span_suggestion_short(
self.token.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());
}
if let Ok(snippet) = self.span_to_snippet(stmt_span) {
e.span_suggestion(
stmt_span,
"try placing this code inside a block",
format!("{{ {} }}", snippet),
// speculative, has been misleading in the past (#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.
crate 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.token.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)) {
if self.token == token::Eof {
break;
}
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.token.span, true)),
span: self.token.span,
})
}
Ok(stmt) => stmt,
};
if let Some(stmt) = stmt {
stmts.push(stmt);
} 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();
// Don't complain about type errors in body tail after parse error (#57383).
let sp = expr.span.to(self.prev_span);
stmt.node = StmtKind::Expr(DummyResult::raw_expr(sp, true));
}
}
}
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.to(self.prev_span);
Ok(Some(stmt))
}
fn warn_missing_semicolon(&self) {
self.diagnostic().struct_span_warn(self.token.span, {
&format!("expected `;`, found {}", self.this_token_descr())
}).note({
"This was erroneously allowed and will become a hard error in a future release"
}).emit();
}
/// 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(Some(self.prev_span))?
} 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,
}
})
}
fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> {
self.expect_keyword(kw::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(kw::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> {
let span_lo = self.token.span;
let (params, span) = if self.eat_lt() {
let params = self.parse_generic_params()?;
self.expect_gt()?;
(params, span_lo.to(self.prev_span))
} else {
(vec![], self.prev_span.between(self.token.span))
};
Ok(ast::Generics {
params,
where_clause: WhereClause {
predicates: Vec::new(),
span: DUMMY_SP,
},
span,
})
}
/// 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> {
let mut where_clause = WhereClause {
predicates: Vec::new(),
span: self.prev_span.to(self.prev_span),
};
if !self.eat_keyword(kw::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.token.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.
// Examples:
// * `for<'a> Trait1<'a>: Trait2<'a /* ok */>`
// * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>`
// * `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(Some(self.prev_span))?;
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_c_variadic: bool)
-> PResult<'a, (Vec<Arg> , bool)> {
let sp = self.token.span;
let mut c_variadic = false;
let (args, _): (Vec<Option<Arg>>, _) = self.parse_paren_comma_seq(|p| {
let do_not_enforce_named_arguments_for_c_variadic =
|token: &token::Token| -> bool {
if token == &token::DotDotDot {
false
} else {
named_args
}
};
match p.parse_arg_general(
false,
allow_c_variadic,
do_not_enforce_named_arguments_for_c_variadic
) {
Ok(arg) => {
if let TyKind::CVarArgs = arg.ty.node {
c_variadic = true;
if p.token != token::CloseDelim(token::Paren) {
let span = p.token.span;
p.span_err(span,
"`...` must be the last argument of a C-variadic function");
Ok(None)
} else {
Ok(Some(arg))
}
} else {
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 (issue #34264).
let span = lo.to(p.prev_span);
Ok(Some(dummy_arg(Ident::new(kw::Invalid, span))))
}
}
})?;
let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
if c_variadic && args.is_empty() {
self.span_err(sp,
"C-variadic function must be declared with at least one named argument");
}
Ok((args, c_variadic))
}
/// Returns the parsed optional self argument and whether a self shortcut was used.
///
/// See `parse_self_arg_with_attrs` to collect attributes.
fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
let expect_ident = |this: &mut Self| match this.token.kind {
// Preserve hygienic context.
token::Ident(name, _) =>
{ let span = this.token.span; this.bump(); Ident::new(name, span) }
_ => unreachable!()
};
let isolated_self = |this: &mut Self, n| {
this.look_ahead(n, |t| t.is_keyword(kw::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.token.span;
let (eself, eself_ident, eself_hi) = match self.token.kind {
token::BinOp(token::And) => {
// `&self`
// `&mut self`
// `&'lt self`
// `&'lt mut self`
// `&not_self`
(if isolated_self(self, 1) {
self.bump();
SelfKind::Region(None, Mutability::Immutable)
} else if self.is_keyword_ahead(1, &[kw::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.is_keyword_ahead(2, &[kw::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.token.span, msg)
.span_label(self.token.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.token.span, msg)
.span_label(self.token.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(kw::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(ThinVec::default(), eself, eself_ident)))
}
/// Returns the parsed optional self argument with attributes and whether a self
/// shortcut was used.
fn parse_self_arg_with_attrs(&mut self) -> PResult<'a, Option<Arg>> {
let attrs = self.parse_arg_attributes()?;
let arg_opt = self.parse_self_arg()?;
Ok(arg_opt.map(|mut arg| {
arg.attrs = attrs.into();
arg
}))
}
/// 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_with_attrs()?;
// Parse the rest of the function parameter list.
let sep = SeqSep::trailing_allowed(token::Comma);
let (mut 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 {
match self.expect_one_of(&[], &[]) {
Err(err) => return Err(err),
Ok(recovered) => (vec![self_arg], recovered),
}
}
} else {
let (input, _, recovered) =
self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?;
(input, recovered)
};
if !recovered {
// Parse closing paren and return type.
self.expect(&token::CloseDelim(token::Paren))?;
}
// Replace duplicated recovered arguments with `_` pattern to avoid unecessary errors.
self.deduplicate_recovered_arg_names(&mut fn_inputs);
Ok(P(FnDecl {
inputs: fn_inputs,
output: self.parse_ret_ty(true)?,
c_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,
c_variadic: false
}))
}
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.is_keyword_ahead(1, &[kw::Const]))
}
/// 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(kw::Crate));
if self.is_crate_vis() {
self.bump(); // `crate`
return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
}
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(respan(self.token.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.is_keyword_ahead(1, &[kw::Crate]) &&
self.look_ahead(2, |t| t != &token::ModSep) // account for `pub(crate::foo)`
{
// `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.is_keyword_ahead(1, &[kw::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.is_keyword_ahead(1, &[kw::Super, kw::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 = path.span;
let help_msg = format!("make this visible only to module `{}` with `in`", path);
self.expect(&token::CloseDelim(token::Paren))?; // `)`
struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg)
.help(suggestion)
.span_suggestion(
sp,
&help_msg,
format!("in {}", path),
Applicability::MachineApplicable,
)
.emit(); // emit diagnostic, but continue with public visibility
}
}
Ok(respan(lo, VisibilityKind::Public))
}
/// 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.kind {
token::Literal(token::Lit { kind: token::Str, symbol, suffix }) |
token::Literal(token::Lit { kind: token::StrRaw(..), symbol, suffix }) => {
let sp = self.token.span;
self.expect_no_suffix(sp, "an ABI spec", suffix);
self.bump();
match abi::lookup(&symbol.as_str()) {
Some(abi) => Ok(Some(abi)),
None => {
let prev_span = self.prev_span;
struct_span_err!(
self.sess.span_diagnostic,
prev_span,
E0703,
"invalid ABI: found `{}`",
symbol
)
.span_label(prev_span, "invalid ABI")
.help(&format!("valid ABIs: {}", abi::all_names().join(", ")))
.emit();
Ok(None)
}
}
}
_ => Ok(None),
}
}
/// We are parsing `async fn`. If we are on Rust 2015, emit an error.
fn ban_async_in_2015(&self, async_span: Span) {
if async_span.rust_2015() {
self.diagnostic()
.struct_span_err_with_code(
async_span,
"`async fn` is not permitted in the 2015 edition",
DiagnosticId::Error("E0670".into())
)
.emit();
}
}
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::take(list))
}
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 if self.token_cursor.stack.get(prev).is_none() {
// This can happen due to a bad interaction of two unrelated recovery mechanisms with
// mismatched delimiters *and* recovery lookahead on the likely typo `pub ident(`
// (#62881).
return Ok((ret?, TokenStream::new(vec![])));
} 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::take(v),
LastToken::Was(ref was) => {
let msg = format!("our vector went away? - found Was({:?})", was);
debug!("collect_tokens: {}", msg);
self.sess.span_diagnostic.delay_span_bug(self.token.span, &msg);
// This can happen due to a bad interaction of two unrelated recovery mechanisms
// with mismatched delimiters *and* recovery lookahead on the likely typo
// `pub ident(` (#62895, different but similar to the case above).
return Ok((ret?, TokenStream::new(vec![])));
}
};
// 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)))
}
/// `::{` 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))
}
pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
let ret = match self.token.kind {
token::Literal(token::Lit { kind: token::Str, symbol, suffix }) =>
(symbol, ast::StrStyle::Cooked, suffix),
token::Literal(token::Lit { kind: token::StrRaw(n), symbol, suffix }) =>
(symbol, ast::StrStyle::Raw(n), suffix),
_ => 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, "a string literal", suf);
Ok((s, style))
}
_ => {
let msg = "expected string literal";
let mut err = self.fatal(msg);
err.span_label(self.token.span, msg);
Err(err)
}
}
}
fn report_invalid_macro_expansion_item(&self) {
self.struct_span_err(
self.prev_span,
"macros that expand to items must be delimited with braces or followed by a semicolon",
).multipart_suggestion(
"change the delimiters to curly braces",
vec![
(self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), String::from(" {")),
(self.prev_span.with_lo(self.prev_span.hi() - BytePos(1)), '}'.to_string()),
],
Applicability::MaybeIncorrect,
).span_suggestion(
self.sess.source_map.next_point(self.prev_span),
"add a semicolon",
';'.to_string(),
Applicability::MaybeIncorrect,
).emit();
}
}
pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, handler: &errors::Handler) {
for unmatched in unclosed_delims.iter() {
let mut err = handler.struct_span_err(unmatched.found_span, &format!(
"incorrect close delimiter: `{}`",
pprust::token_kind_to_string(&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();
}
unclosed_delims.clear();
}
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