2005 lines
82 KiB
Rust
2005 lines
82 KiB
Rust
use super::{Parser, Restrictions, PrevTokenKind, TokenType, PathStyle, BlockMode};
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use super::{SemiColonMode, SeqSep, TokenExpectType};
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use super::pat::{GateOr, PARAM_EXPECTED};
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use super::diagnostics::Error;
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use crate::maybe_recover_from_interpolated_ty_qpath;
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use syntax::ast::{
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self, DUMMY_NODE_ID, Attribute, AttrStyle, Ident, CaptureBy, BlockCheckMode,
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Expr, ExprKind, RangeLimits, Label, Movability, IsAsync, Arm, Ty, TyKind,
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FunctionRetTy, Param, FnDecl, BinOpKind, BinOp, UnOp, Mac, AnonConst, Field, Lit,
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};
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use syntax::token::{self, Token, TokenKind};
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use syntax::print::pprust;
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use syntax::ptr::P;
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use syntax::source_map::{self, Span};
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use syntax::util::classify;
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use syntax::util::literal::LitError;
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use syntax::util::parser::{AssocOp, Fixity, prec_let_scrutinee_needs_par};
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use syntax_pos::symbol::{kw, sym};
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use syntax_pos::Symbol;
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use errors::{PResult, Applicability};
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use std::mem;
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use rustc_data_structures::thin_vec::ThinVec;
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/// Possibly accepts an `token::Interpolated` expression (a pre-parsed expression
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/// dropped into the token stream, which happens while parsing the result of
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/// macro expansion). Placement of these is not as complex as I feared it would
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/// be. The important thing is to make sure that lookahead doesn't balk at
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/// `token::Interpolated` tokens.
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macro_rules! maybe_whole_expr {
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($p:expr) => {
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if let token::Interpolated(nt) = &$p.token.kind {
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match &**nt {
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token::NtExpr(e) | token::NtLiteral(e) => {
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let e = e.clone();
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$p.bump();
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return Ok(e);
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}
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token::NtPath(path) => {
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let path = path.clone();
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$p.bump();
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return Ok($p.mk_expr(
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$p.token.span, ExprKind::Path(None, path), ThinVec::new()
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));
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}
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token::NtBlock(block) => {
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let block = block.clone();
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$p.bump();
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return Ok($p.mk_expr(
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$p.token.span, ExprKind::Block(block, None), ThinVec::new()
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));
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}
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// N.B., `NtIdent(ident)` is normalized to `Ident` in `fn bump`.
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_ => {},
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};
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}
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}
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}
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#[derive(Debug)]
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pub(super) enum LhsExpr {
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NotYetParsed,
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AttributesParsed(ThinVec<Attribute>),
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AlreadyParsed(P<Expr>),
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}
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impl From<Option<ThinVec<Attribute>>> for LhsExpr {
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/// Converts `Some(attrs)` into `LhsExpr::AttributesParsed(attrs)`
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/// and `None` into `LhsExpr::NotYetParsed`.
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///
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/// This conversion does not allocate.
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fn from(o: Option<ThinVec<Attribute>>) -> Self {
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if let Some(attrs) = o {
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LhsExpr::AttributesParsed(attrs)
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} else {
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LhsExpr::NotYetParsed
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}
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}
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}
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impl From<P<Expr>> for LhsExpr {
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/// Converts the `expr: P<Expr>` into `LhsExpr::AlreadyParsed(expr)`.
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///
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/// This conversion does not allocate.
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fn from(expr: P<Expr>) -> Self {
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LhsExpr::AlreadyParsed(expr)
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}
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}
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impl<'a> Parser<'a> {
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/// Parses an expression.
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#[inline]
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pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
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self.parse_expr_res(Restrictions::empty(), None)
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}
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fn parse_paren_expr_seq(&mut self) -> PResult<'a, Vec<P<Expr>>> {
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self.parse_paren_comma_seq(|p| {
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match p.parse_expr() {
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Ok(expr) => Ok(expr),
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Err(mut err) => match p.token.kind {
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token::Ident(name, false)
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if name == kw::Underscore && p.look_ahead(1, |t| {
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t == &token::Comma
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}) => {
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// Special-case handling of `foo(_, _, _)`
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err.emit();
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let sp = p.token.span;
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p.bump();
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Ok(p.mk_expr(sp, ExprKind::Err, ThinVec::new()))
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}
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_ => Err(err),
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},
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}
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}).map(|(r, _)| r)
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}
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/// Parses an expression, subject to the given restrictions.
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#[inline]
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pub(super) fn parse_expr_res(
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&mut self,
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r: Restrictions,
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already_parsed_attrs: Option<ThinVec<Attribute>>
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) -> PResult<'a, P<Expr>> {
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self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
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}
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/// Parses an associative expression.
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///
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/// This parses an expression accounting for associativity and precedence of the operators in
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/// the expression.
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#[inline]
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fn parse_assoc_expr(
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&mut self,
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already_parsed_attrs: Option<ThinVec<Attribute>>,
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) -> PResult<'a, P<Expr>> {
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self.parse_assoc_expr_with(0, already_parsed_attrs.into())
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}
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/// Parses an associative expression with operators of at least `min_prec` precedence.
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pub(super) fn parse_assoc_expr_with(
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&mut self,
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min_prec: usize,
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lhs: LhsExpr,
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) -> PResult<'a, P<Expr>> {
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let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
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expr
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} else {
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let attrs = match lhs {
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LhsExpr::AttributesParsed(attrs) => Some(attrs),
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_ => None,
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};
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if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind) {
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return self.parse_prefix_range_expr(attrs);
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} else {
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self.parse_prefix_expr(attrs)?
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}
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};
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let last_type_ascription_set = self.last_type_ascription.is_some();
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match (self.expr_is_complete(&lhs), AssocOp::from_token(&self.token)) {
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(true, None) => {
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self.last_type_ascription = None;
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// Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
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return Ok(lhs);
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}
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(false, _) => {} // continue parsing the expression
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// An exhaustive check is done in the following block, but these are checked first
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// because they *are* ambiguous but also reasonable looking incorrect syntax, so we
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// want to keep their span info to improve diagnostics in these cases in a later stage.
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(true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;` or `{ 42 } * 3`
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(true, Some(AssocOp::Subtract)) | // `{ 42 } -5`
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(true, Some(AssocOp::LAnd)) | // `{ 42 } &&x` (#61475)
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(true, Some(AssocOp::Add)) // `{ 42 } + 42
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// If the next token is a keyword, then the tokens above *are* unambiguously incorrect:
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// `if x { a } else { b } && if y { c } else { d }`
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if !self.look_ahead(1, |t| t.is_reserved_ident()) => {
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self.last_type_ascription = None;
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// These cases are ambiguous and can't be identified in the parser alone
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let sp = self.sess.source_map().start_point(self.token.span);
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self.sess.ambiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span);
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return Ok(lhs);
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}
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(true, Some(ref op)) if !op.can_continue_expr_unambiguously() => {
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self.last_type_ascription = None;
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return Ok(lhs);
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}
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(true, Some(_)) => {
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// We've found an expression that would be parsed as a statement, but the next
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// token implies this should be parsed as an expression.
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// For example: `if let Some(x) = x { x } else { 0 } / 2`
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let mut err = self.struct_span_err(self.token.span, &format!(
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"expected expression, found `{}`",
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pprust::token_to_string(&self.token),
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));
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err.span_label(self.token.span, "expected expression");
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self.sess.expr_parentheses_needed(
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&mut err,
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lhs.span,
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Some(pprust::expr_to_string(&lhs),
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));
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err.emit();
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}
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}
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self.expected_tokens.push(TokenType::Operator);
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while let Some(op) = AssocOp::from_token(&self.token) {
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// Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
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// it refers to. Interpolated identifiers are unwrapped early and never show up here
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// as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
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// it as "interpolated", it doesn't change the answer for non-interpolated idents.
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let lhs_span = match (self.prev_token_kind, &lhs.kind) {
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(PrevTokenKind::Interpolated, _) => self.prev_span,
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(PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
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if path.segments.len() == 1 => self.prev_span,
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_ => lhs.span,
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};
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let cur_op_span = self.token.span;
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let restrictions = if op.is_assign_like() {
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self.restrictions & Restrictions::NO_STRUCT_LITERAL
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} else {
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self.restrictions
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};
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let prec = op.precedence();
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if prec < min_prec {
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break;
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}
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// Check for deprecated `...` syntax
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if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
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self.err_dotdotdot_syntax(self.token.span);
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}
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if self.token == token::LArrow {
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self.err_larrow_operator(self.token.span);
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}
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self.bump();
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if op.is_comparison() {
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if let Some(expr) = self.check_no_chained_comparison(&lhs, &op)? {
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return Ok(expr);
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}
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}
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// Special cases:
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if op == AssocOp::As {
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lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
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continue
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} else if op == AssocOp::Colon {
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let maybe_path = self.could_ascription_be_path(&lhs.kind);
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self.last_type_ascription = Some((self.prev_span, maybe_path));
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lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type)?;
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self.sess.gated_spans.gate(sym::type_ascription, lhs.span);
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continue
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} else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
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// If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
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// generalise it to the Fixity::None code.
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//
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// We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
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// two variants are handled with `parse_prefix_range_expr` call above.
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let rhs = if self.is_at_start_of_range_notation_rhs() {
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Some(self.parse_assoc_expr_with(prec + 1, LhsExpr::NotYetParsed)?)
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} else {
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None
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};
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let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
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x.span
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} else {
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cur_op_span
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});
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let limits = if op == AssocOp::DotDot {
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RangeLimits::HalfOpen
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} else {
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RangeLimits::Closed
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};
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let r = self.mk_range(Some(lhs), rhs, limits)?;
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lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
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break
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}
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let fixity = op.fixity();
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let prec_adjustment = match fixity {
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Fixity::Right => 0,
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Fixity::Left => 1,
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// We currently have no non-associative operators that are not handled above by
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// the special cases. The code is here only for future convenience.
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Fixity::None => 1,
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};
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let rhs = self.with_res(
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restrictions - Restrictions::STMT_EXPR,
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|this| this.parse_assoc_expr_with(prec + prec_adjustment, LhsExpr::NotYetParsed)
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)?;
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// Make sure that the span of the parent node is larger than the span of lhs and rhs,
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// including the attributes.
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let lhs_span = lhs
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.attrs
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.iter()
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.filter(|a| a.style == AttrStyle::Outer)
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.next()
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.map_or(lhs_span, |a| a.span);
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let span = lhs_span.to(rhs.span);
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lhs = match op {
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AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
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AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
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AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
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AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
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AssocOp::Greater | AssocOp::GreaterEqual => {
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let ast_op = op.to_ast_binop().unwrap();
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let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
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self.mk_expr(span, binary, ThinVec::new())
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}
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AssocOp::Assign => self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
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AssocOp::AssignOp(k) => {
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let aop = match k {
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token::Plus => BinOpKind::Add,
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token::Minus => BinOpKind::Sub,
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token::Star => BinOpKind::Mul,
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token::Slash => BinOpKind::Div,
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token::Percent => BinOpKind::Rem,
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token::Caret => BinOpKind::BitXor,
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token::And => BinOpKind::BitAnd,
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token::Or => BinOpKind::BitOr,
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token::Shl => BinOpKind::Shl,
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token::Shr => BinOpKind::Shr,
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};
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let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
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self.mk_expr(span, aopexpr, ThinVec::new())
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}
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AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
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self.bug("AssocOp should have been handled by special case")
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}
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};
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if let Fixity::None = fixity { break }
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}
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if last_type_ascription_set {
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self.last_type_ascription = None;
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}
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Ok(lhs)
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}
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/// Checks if this expression is a successfully parsed statement.
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fn expr_is_complete(&self, e: &Expr) -> bool {
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self.restrictions.contains(Restrictions::STMT_EXPR) &&
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!classify::expr_requires_semi_to_be_stmt(e)
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}
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fn is_at_start_of_range_notation_rhs(&self) -> bool {
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if self.token.can_begin_expr() {
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// Parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
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if self.token == token::OpenDelim(token::Brace) {
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return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
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}
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true
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} else {
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false
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}
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}
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/// Parses prefix-forms of range notation: `..expr`, `..`, `..=expr`.
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fn parse_prefix_range_expr(
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&mut self,
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already_parsed_attrs: Option<ThinVec<Attribute>>
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) -> PResult<'a, P<Expr>> {
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// Check for deprecated `...` syntax.
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if self.token == token::DotDotDot {
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self.err_dotdotdot_syntax(self.token.span);
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}
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debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind),
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"parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
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self.token);
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let tok = self.token.clone();
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let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
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let lo = self.token.span;
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let mut hi = self.token.span;
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self.bump();
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let opt_end = if self.is_at_start_of_range_notation_rhs() {
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// RHS must be parsed with more associativity than the dots.
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let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
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Some(self.parse_assoc_expr_with(next_prec, LhsExpr::NotYetParsed)
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.map(|x| {
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hi = x.span;
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x
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})?)
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} else {
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None
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};
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let limits = if tok == token::DotDot {
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RangeLimits::HalfOpen
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} else {
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RangeLimits::Closed
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};
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let r = self.mk_range(None, opt_end, limits)?;
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Ok(self.mk_expr(lo.to(hi), r, attrs))
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}
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/// Parses a prefix-unary-operator expr.
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fn parse_prefix_expr(
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&mut self,
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already_parsed_attrs: Option<ThinVec<Attribute>>
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) -> PResult<'a, P<Expr>> {
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let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
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let lo = self.token.span;
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// Note: when adding new unary operators, don't forget to adjust TokenKind::can_begin_expr()
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let (hi, ex) = match self.token.kind {
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token::Not => {
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self.bump();
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let e = self.parse_prefix_expr(None);
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let (span, e) = self.interpolated_or_expr_span(e)?;
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(lo.to(span), self.mk_unary(UnOp::Not, e))
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}
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// Suggest `!` for bitwise negation when encountering a `~`
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token::Tilde => {
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self.bump();
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let e = self.parse_prefix_expr(None);
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let (span, e) = self.interpolated_or_expr_span(e)?;
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let span_of_tilde = lo;
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self.struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator")
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.span_suggestion_short(
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span_of_tilde,
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"use `!` to perform bitwise not",
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"!".to_owned(),
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Applicability::MachineApplicable
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)
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.emit();
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(lo.to(span), self.mk_unary(UnOp::Not, e))
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}
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token::BinOp(token::Minus) => {
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self.bump();
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let e = self.parse_prefix_expr(None);
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let (span, e) = self.interpolated_or_expr_span(e)?;
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(lo.to(span), self.mk_unary(UnOp::Neg, e))
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}
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token::BinOp(token::Star) => {
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self.bump();
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let e = self.parse_prefix_expr(None);
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let (span, e) = self.interpolated_or_expr_span(e)?;
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(lo.to(span), self.mk_unary(UnOp::Deref, e))
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}
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token::BinOp(token::And) | token::AndAnd => {
|
||
self.parse_address_of(lo)?
|
||
}
|
||
token::Ident(..) if self.token.is_keyword(kw::Box) => {
|
||
self.bump();
|
||
let e = self.parse_prefix_expr(None);
|
||
let (span, e) = self.interpolated_or_expr_span(e)?;
|
||
let span = lo.to(span);
|
||
self.sess.gated_spans.gate(sym::box_syntax, span);
|
||
(span, ExprKind::Box(e))
|
||
}
|
||
token::Ident(..) if self.token.is_ident_named(sym::not) => {
|
||
// `not` is just an ordinary identifier in Rust-the-language,
|
||
// but as `rustc`-the-compiler, we can issue clever diagnostics
|
||
// for confused users who really want to say `!`
|
||
let token_cannot_continue_expr = |t: &Token| match t.kind {
|
||
// These tokens can start an expression after `!`, but
|
||
// can't continue an expression after an ident
|
||
token::Ident(name, is_raw) => token::ident_can_begin_expr(name, t.span, is_raw),
|
||
token::Literal(..) | token::Pound => true,
|
||
_ => t.is_whole_expr(),
|
||
};
|
||
let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
|
||
if cannot_continue_expr {
|
||
self.bump();
|
||
// Emit the error ...
|
||
self.struct_span_err(
|
||
self.token.span,
|
||
&format!("unexpected {} after identifier",self.this_token_descr())
|
||
)
|
||
.span_suggestion_short(
|
||
// Span the `not` plus trailing whitespace to avoid
|
||
// trailing whitespace after the `!` in our suggestion
|
||
self.sess.source_map()
|
||
.span_until_non_whitespace(lo.to(self.token.span)),
|
||
"use `!` to perform logical negation",
|
||
"!".to_owned(),
|
||
Applicability::MachineApplicable
|
||
)
|
||
.emit();
|
||
// —and recover! (just as if we were in the block
|
||
// for the `token::Not` arm)
|
||
let e = self.parse_prefix_expr(None);
|
||
let (span, e) = self.interpolated_or_expr_span(e)?;
|
||
(lo.to(span), self.mk_unary(UnOp::Not, e))
|
||
} else {
|
||
return self.parse_dot_or_call_expr(Some(attrs));
|
||
}
|
||
}
|
||
_ => { return self.parse_dot_or_call_expr(Some(attrs)); }
|
||
};
|
||
return Ok(self.mk_expr(lo.to(hi), ex, attrs));
|
||
}
|
||
|
||
/// Returns the span of expr, if it was not interpolated or the span of the interpolated token.
|
||
fn interpolated_or_expr_span(
|
||
&self,
|
||
expr: PResult<'a, P<Expr>>,
|
||
) -> PResult<'a, (Span, P<Expr>)> {
|
||
expr.map(|e| {
|
||
if self.prev_token_kind == PrevTokenKind::Interpolated {
|
||
(self.prev_span, e)
|
||
} else {
|
||
(e.span, e)
|
||
}
|
||
})
|
||
}
|
||
|
||
fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
|
||
expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
|
||
-> PResult<'a, P<Expr>> {
|
||
let mk_expr = |this: &mut Self, rhs: P<Ty>| {
|
||
this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
|
||
};
|
||
|
||
// Save the state of the parser before parsing type normally, in case there is a
|
||
// LessThan comparison after this cast.
|
||
let parser_snapshot_before_type = self.clone();
|
||
match self.parse_ty_no_plus() {
|
||
Ok(rhs) => {
|
||
Ok(mk_expr(self, rhs))
|
||
}
|
||
Err(mut type_err) => {
|
||
// Rewind to before attempting to parse the type with generics, to recover
|
||
// from situations like `x as usize < y` in which we first tried to parse
|
||
// `usize < y` as a type with generic arguments.
|
||
let parser_snapshot_after_type = self.clone();
|
||
mem::replace(self, parser_snapshot_before_type);
|
||
|
||
match self.parse_path(PathStyle::Expr) {
|
||
Ok(path) => {
|
||
let (op_noun, op_verb) = match self.token.kind {
|
||
token::Lt => ("comparison", "comparing"),
|
||
token::BinOp(token::Shl) => ("shift", "shifting"),
|
||
_ => {
|
||
// We can end up here even without `<` being the next token, for
|
||
// example because `parse_ty_no_plus` returns `Err` on keywords,
|
||
// but `parse_path` returns `Ok` on them due to error recovery.
|
||
// Return original error and parser state.
|
||
mem::replace(self, parser_snapshot_after_type);
|
||
return Err(type_err);
|
||
}
|
||
};
|
||
|
||
// Successfully parsed the type path leaving a `<` yet to parse.
|
||
type_err.cancel();
|
||
|
||
// Report non-fatal diagnostics, keep `x as usize` as an expression
|
||
// in AST and continue parsing.
|
||
let msg = format!(
|
||
"`<` is interpreted as a start of generic arguments for `{}`, not a {}",
|
||
pprust::path_to_string(&path),
|
||
op_noun,
|
||
);
|
||
let span_after_type = parser_snapshot_after_type.token.span;
|
||
let expr = mk_expr(self, P(Ty {
|
||
span: path.span,
|
||
kind: TyKind::Path(None, path),
|
||
id: DUMMY_NODE_ID,
|
||
}));
|
||
|
||
let expr_str = self.span_to_snippet(expr.span)
|
||
.unwrap_or_else(|_| pprust::expr_to_string(&expr));
|
||
|
||
self.struct_span_err(self.token.span, &msg)
|
||
.span_label(
|
||
self.look_ahead(1, |t| t.span).to(span_after_type),
|
||
"interpreted as generic arguments"
|
||
)
|
||
.span_label(self.token.span, format!("not interpreted as {}", op_noun))
|
||
.span_suggestion(
|
||
expr.span,
|
||
&format!("try {} the cast value", op_verb),
|
||
format!("({})", expr_str),
|
||
Applicability::MachineApplicable,
|
||
)
|
||
.emit();
|
||
|
||
Ok(expr)
|
||
}
|
||
Err(mut path_err) => {
|
||
// Couldn't parse as a path, return original error and parser state.
|
||
path_err.cancel();
|
||
mem::replace(self, parser_snapshot_after_type);
|
||
Err(type_err)
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Parse `& mut? <expr>` or `& raw [ const | mut ] <expr>`.
|
||
fn parse_address_of(&mut self, lo: Span) -> PResult<'a, (Span, ExprKind)> {
|
||
self.expect_and()?;
|
||
let (k, m) = if self.check_keyword(kw::Raw)
|
||
&& self.look_ahead(1, Token::is_mutability)
|
||
{
|
||
let found_raw = self.eat_keyword(kw::Raw);
|
||
assert!(found_raw);
|
||
let mutability = self.parse_const_or_mut().unwrap();
|
||
self.sess.gated_spans.gate(sym::raw_ref_op, lo.to(self.prev_span));
|
||
(ast::BorrowKind::Raw, mutability)
|
||
} else {
|
||
(ast::BorrowKind::Ref, self.parse_mutability())
|
||
};
|
||
let e = self.parse_prefix_expr(None);
|
||
let (span, e) = self.interpolated_or_expr_span(e)?;
|
||
Ok((lo.to(span), ExprKind::AddrOf(k, m, e)))
|
||
}
|
||
|
||
/// Parses `a.b` or `a(13)` or `a[4]` or just `a`.
|
||
fn parse_dot_or_call_expr(
|
||
&mut self,
|
||
already_parsed_attrs: Option<ThinVec<Attribute>>,
|
||
) -> PResult<'a, P<Expr>> {
|
||
let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
|
||
|
||
let b = self.parse_bottom_expr();
|
||
let (span, b) = self.interpolated_or_expr_span(b)?;
|
||
self.parse_dot_or_call_expr_with(b, span, attrs)
|
||
}
|
||
|
||
pub(super) fn parse_dot_or_call_expr_with(
|
||
&mut self,
|
||
e0: P<Expr>,
|
||
lo: Span,
|
||
mut attrs: ThinVec<Attribute>,
|
||
) -> PResult<'a, P<Expr>> {
|
||
// Stitch the list of outer attributes onto the return value.
|
||
// A little bit ugly, but the best way given the current code
|
||
// structure
|
||
self.parse_dot_or_call_expr_with_(e0, lo).map(|expr|
|
||
expr.map(|mut expr| {
|
||
attrs.extend::<Vec<_>>(expr.attrs.into());
|
||
expr.attrs = attrs;
|
||
match expr.kind {
|
||
ExprKind::If(..) if !expr.attrs.is_empty() => {
|
||
// Just point to the first attribute in there...
|
||
let span = expr.attrs[0].span;
|
||
self.span_err(span, "attributes are not yet allowed on `if` expressions");
|
||
}
|
||
_ => {}
|
||
}
|
||
expr
|
||
})
|
||
)
|
||
}
|
||
|
||
fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
|
||
let mut e = e0;
|
||
let mut hi;
|
||
loop {
|
||
// expr?
|
||
while self.eat(&token::Question) {
|
||
let hi = self.prev_span;
|
||
e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
|
||
}
|
||
|
||
// expr.f
|
||
if self.eat(&token::Dot) {
|
||
match self.token.kind {
|
||
token::Ident(..) => {
|
||
e = self.parse_dot_suffix(e, lo)?;
|
||
}
|
||
token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => {
|
||
let span = self.token.span;
|
||
self.bump();
|
||
let field = ExprKind::Field(e, Ident::new(symbol, span));
|
||
e = self.mk_expr(lo.to(span), field, ThinVec::new());
|
||
|
||
self.expect_no_suffix(span, "a tuple index", suffix);
|
||
}
|
||
token::Literal(token::Lit { kind: token::Float, symbol, .. }) => {
|
||
self.bump();
|
||
let fstr = symbol.as_str();
|
||
let msg = format!("unexpected token: `{}`", symbol);
|
||
let mut err = self.diagnostic().struct_span_err(self.prev_span, &msg);
|
||
err.span_label(self.prev_span, "unexpected token");
|
||
if fstr.chars().all(|x| "0123456789.".contains(x)) {
|
||
let float = match fstr.parse::<f64>().ok() {
|
||
Some(f) => f,
|
||
None => continue,
|
||
};
|
||
let sugg = pprust::to_string(|s| {
|
||
s.popen();
|
||
s.print_expr(&e);
|
||
s.s.word( ".");
|
||
s.print_usize(float.trunc() as usize);
|
||
s.pclose();
|
||
s.s.word(".");
|
||
s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
|
||
});
|
||
err.span_suggestion(
|
||
lo.to(self.prev_span),
|
||
"try parenthesizing the first index",
|
||
sugg,
|
||
Applicability::MachineApplicable
|
||
);
|
||
}
|
||
return Err(err);
|
||
|
||
}
|
||
_ => {
|
||
// FIXME Could factor this out into non_fatal_unexpected or something.
|
||
let actual = self.this_token_to_string();
|
||
self.span_err(self.token.span, &format!("unexpected token: `{}`", actual));
|
||
}
|
||
}
|
||
continue;
|
||
}
|
||
if self.expr_is_complete(&e) { break; }
|
||
match self.token.kind {
|
||
// expr(...)
|
||
token::OpenDelim(token::Paren) => {
|
||
let seq = self.parse_paren_expr_seq().map(|es| {
|
||
let nd = self.mk_call(e, es);
|
||
let hi = self.prev_span;
|
||
self.mk_expr(lo.to(hi), nd, ThinVec::new())
|
||
});
|
||
e = self.recover_seq_parse_error(token::Paren, lo, seq);
|
||
}
|
||
|
||
// expr[...]
|
||
// Could be either an index expression or a slicing expression.
|
||
token::OpenDelim(token::Bracket) => {
|
||
self.bump();
|
||
let ix = self.parse_expr()?;
|
||
hi = self.token.span;
|
||
self.expect(&token::CloseDelim(token::Bracket))?;
|
||
let index = self.mk_index(e, ix);
|
||
e = self.mk_expr(lo.to(hi), index, ThinVec::new())
|
||
}
|
||
_ => return Ok(e)
|
||
}
|
||
}
|
||
return Ok(e);
|
||
}
|
||
|
||
/// Assuming we have just parsed `.`, continue parsing into an expression.
|
||
fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
|
||
if self.token.span.rust_2018() && self.eat_keyword(kw::Await) {
|
||
return self.mk_await_expr(self_arg, lo);
|
||
}
|
||
|
||
let segment = self.parse_path_segment(PathStyle::Expr)?;
|
||
self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren));
|
||
|
||
Ok(match self.token.kind {
|
||
token::OpenDelim(token::Paren) => {
|
||
// Method call `expr.f()`
|
||
let mut args = self.parse_paren_expr_seq()?;
|
||
args.insert(0, self_arg);
|
||
|
||
let span = lo.to(self.prev_span);
|
||
self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
|
||
}
|
||
_ => {
|
||
// Field access `expr.f`
|
||
if let Some(args) = segment.args {
|
||
self.span_err(args.span(),
|
||
"field expressions may not have generic arguments");
|
||
}
|
||
|
||
let span = lo.to(self.prev_span);
|
||
self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
|
||
}
|
||
})
|
||
}
|
||
|
||
/// At the bottom (top?) of the precedence hierarchy,
|
||
/// Parses things like parenthesized exprs, macros, `return`, etc.
|
||
///
|
||
/// N.B., this does not parse outer attributes, and is private because it only works
|
||
/// correctly if called from `parse_dot_or_call_expr()`.
|
||
fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
|
||
maybe_recover_from_interpolated_ty_qpath!(self, true);
|
||
maybe_whole_expr!(self);
|
||
|
||
// Outer attributes are already parsed and will be
|
||
// added to the return value after the fact.
|
||
//
|
||
// Therefore, prevent sub-parser from parsing
|
||
// attributes by giving them a empty "already-parsed" list.
|
||
let mut attrs = ThinVec::new();
|
||
|
||
let lo = self.token.span;
|
||
let mut hi = self.token.span;
|
||
|
||
let ex: ExprKind;
|
||
|
||
macro_rules! parse_lit {
|
||
() => {
|
||
match self.parse_opt_lit() {
|
||
Some(literal) => {
|
||
hi = self.prev_span;
|
||
ex = ExprKind::Lit(literal);
|
||
}
|
||
None => {
|
||
return Err(self.expected_expression_found());
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
// Note: when adding new syntax here, don't forget to adjust `TokenKind::can_begin_expr()`.
|
||
match self.token.kind {
|
||
// This match arm is a special-case of the `_` match arm below and
|
||
// could be removed without changing functionality, but it's faster
|
||
// to have it here, especially for programs with large constants.
|
||
token::Literal(_) => {
|
||
parse_lit!()
|
||
}
|
||
token::OpenDelim(token::Paren) => {
|
||
self.bump();
|
||
|
||
attrs.extend(self.parse_inner_attributes()?);
|
||
|
||
// `(e)` is parenthesized `e`.
|
||
// `(e,)` is a tuple with only one field, `e`.
|
||
let mut es = vec![];
|
||
let mut trailing_comma = false;
|
||
let mut recovered = false;
|
||
while self.token != token::CloseDelim(token::Paren) {
|
||
es.push(match self.parse_expr() {
|
||
Ok(es) => es,
|
||
Err(mut err) => {
|
||
// Recover from parse error in tuple list.
|
||
match self.token.kind {
|
||
token::Ident(name, false)
|
||
if name == kw::Underscore && self.look_ahead(1, |t| {
|
||
t == &token::Comma
|
||
}) => {
|
||
// Special-case handling of `Foo<(_, _, _)>`
|
||
err.emit();
|
||
let sp = self.token.span;
|
||
self.bump();
|
||
self.mk_expr(sp, ExprKind::Err, ThinVec::new())
|
||
}
|
||
_ => return Ok(
|
||
self.recover_seq_parse_error(token::Paren, lo, Err(err)),
|
||
),
|
||
}
|
||
}
|
||
});
|
||
recovered = self.expect_one_of(
|
||
&[],
|
||
&[token::Comma, token::CloseDelim(token::Paren)],
|
||
)?;
|
||
if self.eat(&token::Comma) {
|
||
trailing_comma = true;
|
||
} else {
|
||
trailing_comma = false;
|
||
break;
|
||
}
|
||
}
|
||
if !recovered {
|
||
self.bump();
|
||
}
|
||
|
||
hi = self.prev_span;
|
||
ex = if es.len() == 1 && !trailing_comma {
|
||
ExprKind::Paren(es.into_iter().nth(0).unwrap())
|
||
} else {
|
||
ExprKind::Tup(es)
|
||
};
|
||
}
|
||
token::OpenDelim(token::Brace) => {
|
||
return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
|
||
}
|
||
token::BinOp(token::Or) | token::OrOr => {
|
||
return self.parse_closure_expr(attrs);
|
||
}
|
||
token::OpenDelim(token::Bracket) => {
|
||
self.bump();
|
||
|
||
attrs.extend(self.parse_inner_attributes()?);
|
||
|
||
if self.eat(&token::CloseDelim(token::Bracket)) {
|
||
// Empty vector
|
||
ex = ExprKind::Array(Vec::new());
|
||
} else {
|
||
// Non-empty vector
|
||
let first_expr = self.parse_expr()?;
|
||
if self.eat(&token::Semi) {
|
||
// Repeating array syntax: `[ 0; 512 ]`
|
||
let count = AnonConst {
|
||
id: DUMMY_NODE_ID,
|
||
value: self.parse_expr()?,
|
||
};
|
||
self.expect(&token::CloseDelim(token::Bracket))?;
|
||
ex = ExprKind::Repeat(first_expr, count);
|
||
} else if self.eat(&token::Comma) {
|
||
// Vector with two or more elements
|
||
let remaining_exprs = self.parse_seq_to_end(
|
||
&token::CloseDelim(token::Bracket),
|
||
SeqSep::trailing_allowed(token::Comma),
|
||
|p| Ok(p.parse_expr()?)
|
||
)?;
|
||
let mut exprs = vec![first_expr];
|
||
exprs.extend(remaining_exprs);
|
||
ex = ExprKind::Array(exprs);
|
||
} else {
|
||
// Vector with one element
|
||
self.expect(&token::CloseDelim(token::Bracket))?;
|
||
ex = ExprKind::Array(vec![first_expr]);
|
||
}
|
||
}
|
||
hi = self.prev_span;
|
||
}
|
||
_ => {
|
||
if self.eat_lt() {
|
||
let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
|
||
hi = path.span;
|
||
return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
|
||
}
|
||
if self.token.is_path_start() {
|
||
let path = self.parse_path(PathStyle::Expr)?;
|
||
|
||
// `!`, as an operator, is prefix, so we know this isn't that.
|
||
if self.eat(&token::Not) {
|
||
// MACRO INVOCATION expression
|
||
let (delim, tts) = self.expect_delimited_token_tree()?;
|
||
hi = self.prev_span;
|
||
ex = ExprKind::Mac(Mac {
|
||
path,
|
||
tts,
|
||
delim,
|
||
span: lo.to(hi),
|
||
prior_type_ascription: self.last_type_ascription,
|
||
});
|
||
} else if self.check(&token::OpenDelim(token::Brace)) {
|
||
if let Some(expr) = self.maybe_parse_struct_expr(lo, &path, &attrs) {
|
||
return expr;
|
||
} else {
|
||
hi = path.span;
|
||
ex = ExprKind::Path(None, path);
|
||
}
|
||
} else {
|
||
hi = path.span;
|
||
ex = ExprKind::Path(None, path);
|
||
}
|
||
|
||
let expr = self.mk_expr(lo.to(hi), ex, attrs);
|
||
return self.maybe_recover_from_bad_qpath(expr, true);
|
||
}
|
||
if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
|
||
return self.parse_closure_expr(attrs);
|
||
}
|
||
if self.eat_keyword(kw::If) {
|
||
return self.parse_if_expr(attrs);
|
||
}
|
||
if self.eat_keyword(kw::For) {
|
||
let lo = self.prev_span;
|
||
return self.parse_for_expr(None, lo, attrs);
|
||
}
|
||
if self.eat_keyword(kw::While) {
|
||
let lo = self.prev_span;
|
||
return self.parse_while_expr(None, lo, attrs);
|
||
}
|
||
if let Some(label) = self.eat_label() {
|
||
let lo = label.ident.span;
|
||
self.expect(&token::Colon)?;
|
||
if self.eat_keyword(kw::While) {
|
||
return self.parse_while_expr(Some(label), lo, attrs)
|
||
}
|
||
if self.eat_keyword(kw::For) {
|
||
return self.parse_for_expr(Some(label), lo, attrs)
|
||
}
|
||
if self.eat_keyword(kw::Loop) {
|
||
return self.parse_loop_expr(Some(label), lo, attrs)
|
||
}
|
||
if self.token == token::OpenDelim(token::Brace) {
|
||
return self.parse_block_expr(Some(label),
|
||
lo,
|
||
BlockCheckMode::Default,
|
||
attrs);
|
||
}
|
||
let msg = "expected `while`, `for`, `loop` or `{` after a label";
|
||
let mut err = self.fatal(msg);
|
||
err.span_label(self.token.span, msg);
|
||
return Err(err);
|
||
}
|
||
if self.eat_keyword(kw::Loop) {
|
||
let lo = self.prev_span;
|
||
return self.parse_loop_expr(None, lo, attrs);
|
||
}
|
||
if self.eat_keyword(kw::Continue) {
|
||
let label = self.eat_label();
|
||
let ex = ExprKind::Continue(label);
|
||
let hi = self.prev_span;
|
||
return Ok(self.mk_expr(lo.to(hi), ex, attrs));
|
||
}
|
||
if self.eat_keyword(kw::Match) {
|
||
let match_sp = self.prev_span;
|
||
return self.parse_match_expr(attrs).map_err(|mut err| {
|
||
err.span_label(match_sp, "while parsing this match expression");
|
||
err
|
||
});
|
||
}
|
||
if self.eat_keyword(kw::Unsafe) {
|
||
return self.parse_block_expr(
|
||
None,
|
||
lo,
|
||
BlockCheckMode::Unsafe(ast::UserProvided),
|
||
attrs);
|
||
}
|
||
if self.is_do_catch_block() {
|
||
let mut db = self.fatal("found removed `do catch` syntax");
|
||
db.help("following RFC #2388, the new non-placeholder syntax is `try`");
|
||
return Err(db);
|
||
}
|
||
if self.is_try_block() {
|
||
let lo = self.token.span;
|
||
assert!(self.eat_keyword(kw::Try));
|
||
return self.parse_try_block(lo, attrs);
|
||
}
|
||
|
||
// `Span::rust_2018()` is somewhat expensive; don't get it repeatedly.
|
||
let is_span_rust_2018 = self.token.span.rust_2018();
|
||
if is_span_rust_2018 && self.check_keyword(kw::Async) {
|
||
return if self.is_async_block() { // Check for `async {` and `async move {`.
|
||
self.parse_async_block(attrs)
|
||
} else {
|
||
self.parse_closure_expr(attrs)
|
||
};
|
||
}
|
||
if self.eat_keyword(kw::Return) {
|
||
if self.token.can_begin_expr() {
|
||
let e = self.parse_expr()?;
|
||
hi = e.span;
|
||
ex = ExprKind::Ret(Some(e));
|
||
} else {
|
||
ex = ExprKind::Ret(None);
|
||
}
|
||
} else if self.eat_keyword(kw::Break) {
|
||
let label = self.eat_label();
|
||
let e = if self.token.can_begin_expr()
|
||
&& !(self.token == token::OpenDelim(token::Brace)
|
||
&& self.restrictions.contains(
|
||
Restrictions::NO_STRUCT_LITERAL)) {
|
||
Some(self.parse_expr()?)
|
||
} else {
|
||
None
|
||
};
|
||
ex = ExprKind::Break(label, e);
|
||
hi = self.prev_span;
|
||
} else if self.eat_keyword(kw::Yield) {
|
||
if self.token.can_begin_expr() {
|
||
let e = self.parse_expr()?;
|
||
hi = e.span;
|
||
ex = ExprKind::Yield(Some(e));
|
||
} else {
|
||
ex = ExprKind::Yield(None);
|
||
}
|
||
|
||
let span = lo.to(hi);
|
||
self.sess.gated_spans.gate(sym::generators, span);
|
||
} else if self.eat_keyword(kw::Let) {
|
||
return self.parse_let_expr(attrs);
|
||
} else if is_span_rust_2018 && self.eat_keyword(kw::Await) {
|
||
let (await_hi, e_kind) = self.parse_incorrect_await_syntax(lo, self.prev_span)?;
|
||
hi = await_hi;
|
||
ex = e_kind;
|
||
} else {
|
||
if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
|
||
// Don't complain about bare semicolons after unclosed braces
|
||
// recovery in order to keep the error count down. Fixing the
|
||
// delimiters will possibly also fix the bare semicolon found in
|
||
// expression context. For example, silence the following error:
|
||
//
|
||
// error: expected expression, found `;`
|
||
// --> file.rs:2:13
|
||
// |
|
||
// 2 | foo(bar(;
|
||
// | ^ expected expression
|
||
self.bump();
|
||
return Ok(self.mk_expr(self.token.span, ExprKind::Err, ThinVec::new()));
|
||
}
|
||
parse_lit!()
|
||
}
|
||
}
|
||
}
|
||
|
||
let expr = self.mk_expr(lo.to(hi), ex, attrs);
|
||
self.maybe_recover_from_bad_qpath(expr, true)
|
||
}
|
||
|
||
/// Returns a string literal if the next token is a string literal.
|
||
/// In case of error returns `Some(lit)` if the next token is a literal with a wrong kind,
|
||
/// and returns `None` if the next token is not literal at all.
|
||
pub fn parse_str_lit(&mut self) -> Result<ast::StrLit, Option<Lit>> {
|
||
match self.parse_opt_lit() {
|
||
Some(lit) => match lit.kind {
|
||
ast::LitKind::Str(symbol_unescaped, style) => Ok(ast::StrLit {
|
||
style,
|
||
symbol: lit.token.symbol,
|
||
suffix: lit.token.suffix,
|
||
span: lit.span,
|
||
symbol_unescaped,
|
||
}),
|
||
_ => Err(Some(lit)),
|
||
}
|
||
None => Err(None),
|
||
}
|
||
}
|
||
|
||
pub(super) fn parse_lit(&mut self) -> PResult<'a, Lit> {
|
||
self.parse_opt_lit().ok_or_else(|| {
|
||
let msg = format!("unexpected token: {}", self.this_token_descr());
|
||
self.span_fatal(self.token.span, &msg)
|
||
})
|
||
}
|
||
|
||
/// Matches `lit = true | false | token_lit`.
|
||
/// Returns `None` if the next token is not a literal.
|
||
pub(super) fn parse_opt_lit(&mut self) -> Option<Lit> {
|
||
let mut recovered = None;
|
||
if self.token == token::Dot {
|
||
// Attempt to recover `.4` as `0.4`. We don't currently have any syntax where
|
||
// dot would follow an optional literal, so we do this unconditionally.
|
||
recovered = self.look_ahead(1, |next_token| {
|
||
if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix })
|
||
= next_token.kind {
|
||
if self.token.span.hi() == next_token.span.lo() {
|
||
let s = String::from("0.") + &symbol.as_str();
|
||
let kind = TokenKind::lit(token::Float, Symbol::intern(&s), suffix);
|
||
return Some(Token::new(kind, self.token.span.to(next_token.span)));
|
||
}
|
||
}
|
||
None
|
||
});
|
||
if let Some(token) = &recovered {
|
||
self.bump();
|
||
self.struct_span_err(token.span, "float literals must have an integer part")
|
||
.span_suggestion(
|
||
token.span,
|
||
"must have an integer part",
|
||
pprust::token_to_string(token),
|
||
Applicability::MachineApplicable,
|
||
)
|
||
.emit();
|
||
}
|
||
}
|
||
|
||
let token = recovered.as_ref().unwrap_or(&self.token);
|
||
match Lit::from_token(token) {
|
||
Ok(lit) => {
|
||
self.bump();
|
||
Some(lit)
|
||
}
|
||
Err(LitError::NotLiteral) => {
|
||
None
|
||
}
|
||
Err(err) => {
|
||
let span = token.span;
|
||
let lit = match token.kind {
|
||
token::Literal(lit) => lit,
|
||
_ => unreachable!(),
|
||
};
|
||
self.bump();
|
||
self.report_lit_error(err, lit, span);
|
||
// Pack possible quotes and prefixes from the original literal into
|
||
// the error literal's symbol so they can be pretty-printed faithfully.
|
||
let suffixless_lit = token::Lit::new(lit.kind, lit.symbol, None);
|
||
let symbol = Symbol::intern(&suffixless_lit.to_string());
|
||
let lit = token::Lit::new(token::Err, symbol, lit.suffix);
|
||
Some(Lit::from_lit_token(lit, span).unwrap_or_else(|_| unreachable!()))
|
||
}
|
||
}
|
||
}
|
||
|
||
fn report_lit_error(&self, err: LitError, lit: token::Lit, span: Span) {
|
||
// Checks if `s` looks like i32 or u1234 etc.
|
||
fn looks_like_width_suffix(first_chars: &[char], s: &str) -> bool {
|
||
s.len() > 1
|
||
&& s.starts_with(first_chars)
|
||
&& s[1..].chars().all(|c| c.is_ascii_digit())
|
||
}
|
||
|
||
let token::Lit { kind, suffix, .. } = lit;
|
||
match err {
|
||
// `NotLiteral` is not an error by itself, so we don't report
|
||
// it and give the parser opportunity to try something else.
|
||
LitError::NotLiteral => {}
|
||
// `LexerError` *is* an error, but it was already reported
|
||
// by lexer, so here we don't report it the second time.
|
||
LitError::LexerError => {}
|
||
LitError::InvalidSuffix => {
|
||
self.expect_no_suffix(
|
||
span,
|
||
&format!("{} {} literal", kind.article(), kind.descr()),
|
||
suffix,
|
||
);
|
||
}
|
||
LitError::InvalidIntSuffix => {
|
||
let suf = suffix.expect("suffix error with no suffix").as_str();
|
||
if looks_like_width_suffix(&['i', 'u'], &suf) {
|
||
// If it looks like a width, try to be helpful.
|
||
let msg = format!("invalid width `{}` for integer literal", &suf[1..]);
|
||
self.struct_span_err(span, &msg)
|
||
.help("valid widths are 8, 16, 32, 64 and 128")
|
||
.emit();
|
||
} else {
|
||
let msg = format!("invalid suffix `{}` for integer literal", suf);
|
||
self.struct_span_err(span, &msg)
|
||
.span_label(span, format!("invalid suffix `{}`", suf))
|
||
.help("the suffix must be one of the integral types (`u32`, `isize`, etc)")
|
||
.emit();
|
||
}
|
||
}
|
||
LitError::InvalidFloatSuffix => {
|
||
let suf = suffix.expect("suffix error with no suffix").as_str();
|
||
if looks_like_width_suffix(&['f'], &suf) {
|
||
// If it looks like a width, try to be helpful.
|
||
let msg = format!("invalid width `{}` for float literal", &suf[1..]);
|
||
self.struct_span_err(span, &msg)
|
||
.help("valid widths are 32 and 64")
|
||
.emit();
|
||
} else {
|
||
let msg = format!("invalid suffix `{}` for float literal", suf);
|
||
self.struct_span_err(span, &msg)
|
||
.span_label(span, format!("invalid suffix `{}`", suf))
|
||
.help("valid suffixes are `f32` and `f64`")
|
||
.emit();
|
||
}
|
||
}
|
||
LitError::NonDecimalFloat(base) => {
|
||
let descr = match base {
|
||
16 => "hexadecimal",
|
||
8 => "octal",
|
||
2 => "binary",
|
||
_ => unreachable!(),
|
||
};
|
||
self.struct_span_err(span, &format!("{} float literal is not supported", descr))
|
||
.span_label(span, "not supported")
|
||
.emit();
|
||
}
|
||
LitError::IntTooLarge => {
|
||
self.struct_span_err(span, "integer literal is too large")
|
||
.emit();
|
||
}
|
||
}
|
||
}
|
||
|
||
pub(super) fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<Symbol>) {
|
||
if let Some(suf) = suffix {
|
||
let mut err = if kind == "a tuple index"
|
||
&& [sym::i32, sym::u32, sym::isize, sym::usize].contains(&suf)
|
||
{
|
||
// #59553: warn instead of reject out of hand to allow the fix to percolate
|
||
// through the ecosystem when people fix their macros
|
||
let mut err = self.sess.span_diagnostic.struct_span_warn(
|
||
sp,
|
||
&format!("suffixes on {} are invalid", kind),
|
||
);
|
||
err.note(&format!(
|
||
"`{}` is *temporarily* accepted on tuple index fields as it was \
|
||
incorrectly accepted on stable for a few releases",
|
||
suf,
|
||
));
|
||
err.help(
|
||
"on proc macros, you'll want to use `syn::Index::from` or \
|
||
`proc_macro::Literal::*_unsuffixed` for code that will desugar \
|
||
to tuple field access",
|
||
);
|
||
err.note(
|
||
"for more context, see https://github.com/rust-lang/rust/issues/60210",
|
||
);
|
||
err
|
||
} else {
|
||
self.struct_span_err(sp, &format!("suffixes on {} are invalid", kind))
|
||
};
|
||
err.span_label(sp, format!("invalid suffix `{}`", suf));
|
||
err.emit();
|
||
}
|
||
}
|
||
|
||
/// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`).
|
||
pub fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
|
||
maybe_whole_expr!(self);
|
||
|
||
let minus_lo = self.token.span;
|
||
let minus_present = self.eat(&token::BinOp(token::Minus));
|
||
let lo = self.token.span;
|
||
let literal = self.parse_lit()?;
|
||
let hi = self.prev_span;
|
||
let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
|
||
|
||
if minus_present {
|
||
let minus_hi = self.prev_span;
|
||
let unary = self.mk_unary(UnOp::Neg, expr);
|
||
Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
|
||
} else {
|
||
Ok(expr)
|
||
}
|
||
}
|
||
|
||
/// Parses a block or unsafe block.
|
||
pub(super) fn parse_block_expr(
|
||
&mut self,
|
||
opt_label: Option<Label>,
|
||
lo: Span,
|
||
blk_mode: BlockCheckMode,
|
||
outer_attrs: ThinVec<Attribute>,
|
||
) -> PResult<'a, P<Expr>> {
|
||
if let Some(label) = opt_label {
|
||
self.sess.gated_spans.gate(sym::label_break_value, label.ident.span);
|
||
}
|
||
|
||
self.expect(&token::OpenDelim(token::Brace))?;
|
||
|
||
let mut attrs = outer_attrs;
|
||
attrs.extend(self.parse_inner_attributes()?);
|
||
|
||
let blk = self.parse_block_tail(lo, blk_mode)?;
|
||
Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs))
|
||
}
|
||
|
||
/// Parses a closure expression (e.g., `move |args| expr`).
|
||
fn parse_closure_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
|
||
let lo = self.token.span;
|
||
|
||
let movability = if self.eat_keyword(kw::Static) {
|
||
Movability::Static
|
||
} else {
|
||
Movability::Movable
|
||
};
|
||
|
||
let asyncness = if self.token.span.rust_2018() {
|
||
self.parse_asyncness()
|
||
} else {
|
||
IsAsync::NotAsync
|
||
};
|
||
if asyncness.is_async() {
|
||
// Feature-gate `async ||` closures.
|
||
self.sess.gated_spans.gate(sym::async_closure, self.prev_span);
|
||
}
|
||
|
||
let capture_clause = self.parse_capture_clause();
|
||
let decl = self.parse_fn_block_decl()?;
|
||
let decl_hi = self.prev_span;
|
||
let body = match decl.output {
|
||
FunctionRetTy::Default(_) => {
|
||
let restrictions = self.restrictions - Restrictions::STMT_EXPR;
|
||
self.parse_expr_res(restrictions, None)?
|
||
},
|
||
_ => {
|
||
// If an explicit return type is given, require a block to appear (RFC 968).
|
||
let body_lo = self.token.span;
|
||
self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
|
||
}
|
||
};
|
||
|
||
Ok(self.mk_expr(
|
||
lo.to(body.span),
|
||
ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
|
||
attrs))
|
||
}
|
||
|
||
/// Parses an optional `move` prefix to a closure lke construct.
|
||
fn parse_capture_clause(&mut self) -> CaptureBy {
|
||
if self.eat_keyword(kw::Move) {
|
||
CaptureBy::Value
|
||
} else {
|
||
CaptureBy::Ref
|
||
}
|
||
}
|
||
|
||
/// 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_param()
|
||
)?.0;
|
||
self.expect_or()?;
|
||
args
|
||
}
|
||
};
|
||
let output = self.parse_ret_ty(true)?;
|
||
|
||
Ok(P(FnDecl {
|
||
inputs: inputs_captures,
|
||
output,
|
||
}))
|
||
}
|
||
|
||
/// Parses a parameter in a closure header (e.g., `|arg, arg|`).
|
||
fn parse_fn_block_param(&mut self) -> PResult<'a, Param> {
|
||
let lo = self.token.span;
|
||
let attrs = self.parse_outer_attributes()?;
|
||
let pat = self.parse_pat(PARAM_EXPECTED)?;
|
||
let t = if self.eat(&token::Colon) {
|
||
self.parse_ty()?
|
||
} else {
|
||
P(Ty {
|
||
id: DUMMY_NODE_ID,
|
||
kind: TyKind::Infer,
|
||
span: self.prev_span,
|
||
})
|
||
};
|
||
let span = lo.to(self.token.span);
|
||
Ok(Param {
|
||
attrs: attrs.into(),
|
||
ty: t,
|
||
pat,
|
||
span,
|
||
id: DUMMY_NODE_ID,
|
||
is_placeholder: false,
|
||
})
|
||
}
|
||
|
||
/// Parses an `if` expression (`if` token already eaten).
|
||
fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
|
||
let lo = self.prev_span;
|
||
let cond = self.parse_cond_expr()?;
|
||
|
||
// Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
|
||
// verify that the last statement is either an implicit return (no `;`) or an explicit
|
||
// return. This won't catch blocks with an explicit `return`, but that would be caught by
|
||
// the dead code lint.
|
||
if self.eat_keyword(kw::Else) || !cond.returns() {
|
||
let sp = self.sess.source_map().next_point(lo);
|
||
let mut err = self.diagnostic()
|
||
.struct_span_err(sp, "missing condition for `if` expression");
|
||
err.span_label(sp, "expected if condition here");
|
||
return Err(err)
|
||
}
|
||
let not_block = self.token != token::OpenDelim(token::Brace);
|
||
let thn = self.parse_block().map_err(|mut err| {
|
||
if not_block {
|
||
err.span_label(lo, "this `if` statement has a condition, but no block");
|
||
}
|
||
err
|
||
})?;
|
||
let mut els: Option<P<Expr>> = None;
|
||
let mut hi = thn.span;
|
||
if self.eat_keyword(kw::Else) {
|
||
let elexpr = self.parse_else_expr()?;
|
||
hi = elexpr.span;
|
||
els = Some(elexpr);
|
||
}
|
||
Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
|
||
}
|
||
|
||
/// Parses the condition of a `if` or `while` expression.
|
||
fn parse_cond_expr(&mut self) -> PResult<'a, P<Expr>> {
|
||
let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
|
||
|
||
if let ExprKind::Let(..) = cond.kind {
|
||
// Remove the last feature gating of a `let` expression since it's stable.
|
||
self.sess.gated_spans.ungate_last(sym::let_chains, cond.span);
|
||
}
|
||
|
||
Ok(cond)
|
||
}
|
||
|
||
/// Parses a `let $pat = $expr` pseudo-expression.
|
||
/// The `let` token has already been eaten.
|
||
fn parse_let_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
|
||
let lo = self.prev_span;
|
||
let pat = self.parse_top_pat(GateOr::No)?;
|
||
self.expect(&token::Eq)?;
|
||
let expr = self.with_res(
|
||
Restrictions::NO_STRUCT_LITERAL,
|
||
|this| this.parse_assoc_expr_with(1 + prec_let_scrutinee_needs_par(), None.into())
|
||
)?;
|
||
let span = lo.to(expr.span);
|
||
self.sess.gated_spans.gate(sym::let_chains, span);
|
||
Ok(self.mk_expr(span, ExprKind::Let(pat, expr), attrs))
|
||
}
|
||
|
||
/// Parses an `else { ... }` expression (`else` token already eaten).
|
||
fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
|
||
if self.eat_keyword(kw::If) {
|
||
return self.parse_if_expr(ThinVec::new());
|
||
} else {
|
||
let blk = self.parse_block()?;
|
||
return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
|
||
}
|
||
}
|
||
|
||
/// Parses a `for ... in` expression (`for` token already eaten).
|
||
fn parse_for_expr(
|
||
&mut self,
|
||
opt_label: Option<Label>,
|
||
span_lo: Span,
|
||
mut attrs: ThinVec<Attribute>
|
||
) -> PResult<'a, P<Expr>> {
|
||
// Parse: `for <src_pat> in <src_expr> <src_loop_block>`
|
||
|
||
// Record whether we are about to parse `for (`.
|
||
// This is used below for recovery in case of `for ( $stuff ) $block`
|
||
// in which case we will suggest `for $stuff $block`.
|
||
let begin_paren = match self.token.kind {
|
||
token::OpenDelim(token::Paren) => Some(self.token.span),
|
||
_ => None,
|
||
};
|
||
|
||
let pat = self.parse_top_pat(GateOr::Yes)?;
|
||
if !self.eat_keyword(kw::In) {
|
||
let in_span = self.prev_span.between(self.token.span);
|
||
self.struct_span_err(in_span, "missing `in` in `for` loop")
|
||
.span_suggestion_short(
|
||
in_span,
|
||
"try adding `in` here", " in ".into(),
|
||
// has been misleading, at least in the past (closed Issue #48492)
|
||
Applicability::MaybeIncorrect
|
||
)
|
||
.emit();
|
||
}
|
||
let in_span = self.prev_span;
|
||
self.check_for_for_in_in_typo(in_span);
|
||
let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
|
||
|
||
let pat = self.recover_parens_around_for_head(pat, &expr, begin_paren);
|
||
|
||
let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
|
||
attrs.extend(iattrs);
|
||
|
||
let hi = self.prev_span;
|
||
Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
|
||
}
|
||
|
||
/// Parses a `while` or `while let` expression (`while` token already eaten).
|
||
fn parse_while_expr(
|
||
&mut self,
|
||
opt_label: Option<Label>,
|
||
span_lo: Span,
|
||
mut attrs: ThinVec<Attribute>
|
||
) -> PResult<'a, P<Expr>> {
|
||
let cond = self.parse_cond_expr()?;
|
||
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
|
||
attrs.extend(iattrs);
|
||
let span = span_lo.to(body.span);
|
||
Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs))
|
||
}
|
||
|
||
/// Parses `loop { ... }` (`loop` token already eaten).
|
||
fn parse_loop_expr(
|
||
&mut self,
|
||
opt_label: Option<Label>,
|
||
span_lo: Span,
|
||
mut attrs: ThinVec<Attribute>
|
||
) -> PResult<'a, P<Expr>> {
|
||
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
|
||
attrs.extend(iattrs);
|
||
let span = span_lo.to(body.span);
|
||
Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
|
||
}
|
||
|
||
fn eat_label(&mut self) -> Option<Label> {
|
||
if let Some(ident) = self.token.lifetime() {
|
||
let span = self.token.span;
|
||
self.bump();
|
||
Some(Label { ident: Ident::new(ident.name, span) })
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
/// Parses a `match ... { ... }` expression (`match` token already eaten).
|
||
fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
|
||
let match_span = self.prev_span;
|
||
let lo = self.prev_span;
|
||
let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
|
||
if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
|
||
if self.token == token::Semi {
|
||
e.span_suggestion_short(
|
||
match_span,
|
||
"try removing this `match`",
|
||
String::new(),
|
||
Applicability::MaybeIncorrect // speculative
|
||
);
|
||
}
|
||
return Err(e)
|
||
}
|
||
attrs.extend(self.parse_inner_attributes()?);
|
||
|
||
let mut arms: Vec<Arm> = Vec::new();
|
||
while self.token != token::CloseDelim(token::Brace) {
|
||
match self.parse_arm() {
|
||
Ok(arm) => arms.push(arm),
|
||
Err(mut e) => {
|
||
// Recover by skipping to the end of the block.
|
||
e.emit();
|
||
self.recover_stmt();
|
||
let span = lo.to(self.token.span);
|
||
if self.token == token::CloseDelim(token::Brace) {
|
||
self.bump();
|
||
}
|
||
return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
|
||
}
|
||
}
|
||
}
|
||
let hi = self.token.span;
|
||
self.bump();
|
||
return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
|
||
}
|
||
|
||
pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> {
|
||
let attrs = self.parse_outer_attributes()?;
|
||
let lo = self.token.span;
|
||
let pat = self.parse_top_pat(GateOr::No)?;
|
||
let guard = if self.eat_keyword(kw::If) {
|
||
Some(self.parse_expr()?)
|
||
} else {
|
||
None
|
||
};
|
||
let arrow_span = self.token.span;
|
||
self.expect(&token::FatArrow)?;
|
||
let arm_start_span = self.token.span;
|
||
|
||
let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
|
||
.map_err(|mut err| {
|
||
err.span_label(arrow_span, "while parsing the `match` arm starting here");
|
||
err
|
||
})?;
|
||
|
||
let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
|
||
&& self.token != token::CloseDelim(token::Brace);
|
||
|
||
let hi = self.token.span;
|
||
|
||
if require_comma {
|
||
let cm = self.sess.source_map();
|
||
self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
|
||
.map_err(|mut err| {
|
||
match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
|
||
(Ok(ref expr_lines), Ok(ref arm_start_lines))
|
||
if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
|
||
&& expr_lines.lines.len() == 2
|
||
&& self.token == token::FatArrow => {
|
||
// We check whether there's any trailing code in the parse span,
|
||
// if there isn't, we very likely have the following:
|
||
//
|
||
// X | &Y => "y"
|
||
// | -- - missing comma
|
||
// | |
|
||
// | arrow_span
|
||
// X | &X => "x"
|
||
// | - ^^ self.token.span
|
||
// | |
|
||
// | parsed until here as `"y" & X`
|
||
err.span_suggestion_short(
|
||
cm.next_point(arm_start_span),
|
||
"missing a comma here to end this `match` arm",
|
||
",".to_owned(),
|
||
Applicability::MachineApplicable
|
||
);
|
||
}
|
||
_ => {
|
||
err.span_label(arrow_span,
|
||
"while parsing the `match` arm starting here");
|
||
}
|
||
}
|
||
err
|
||
})?;
|
||
} else {
|
||
self.eat(&token::Comma);
|
||
}
|
||
|
||
Ok(ast::Arm {
|
||
attrs,
|
||
pat,
|
||
guard,
|
||
body: expr,
|
||
span: lo.to(hi),
|
||
id: DUMMY_NODE_ID,
|
||
is_placeholder: false,
|
||
})
|
||
}
|
||
|
||
/// Parses a `try {...}` expression (`try` token already eaten).
|
||
fn parse_try_block(
|
||
&mut self,
|
||
span_lo: Span,
|
||
mut attrs: ThinVec<Attribute>
|
||
) -> PResult<'a, P<Expr>> {
|
||
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
|
||
attrs.extend(iattrs);
|
||
if self.eat_keyword(kw::Catch) {
|
||
let mut error = self.struct_span_err(self.prev_span,
|
||
"keyword `catch` cannot follow a `try` block");
|
||
error.help("try using `match` on the result of the `try` block instead");
|
||
error.emit();
|
||
Err(error)
|
||
} else {
|
||
let span = span_lo.to(body.span);
|
||
self.sess.gated_spans.gate(sym::try_blocks, span);
|
||
Ok(self.mk_expr(span, ExprKind::TryBlock(body), attrs))
|
||
}
|
||
}
|
||
|
||
fn is_do_catch_block(&self) -> bool {
|
||
self.token.is_keyword(kw::Do) &&
|
||
self.is_keyword_ahead(1, &[kw::Catch]) &&
|
||
self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
|
||
!self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
|
||
}
|
||
|
||
fn is_try_block(&self) -> bool {
|
||
self.token.is_keyword(kw::Try) &&
|
||
self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
|
||
self.token.span.rust_2018() &&
|
||
// Prevent `while try {} {}`, `if try {} {} else {}`, etc.
|
||
!self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
|
||
}
|
||
|
||
/// Parses an `async move? {...}` expression.
|
||
fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
|
||
let span_lo = self.token.span;
|
||
self.expect_keyword(kw::Async)?;
|
||
let capture_clause = self.parse_capture_clause();
|
||
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
|
||
attrs.extend(iattrs);
|
||
Ok(self.mk_expr(
|
||
span_lo.to(body.span),
|
||
ExprKind::Async(capture_clause, DUMMY_NODE_ID, body), attrs))
|
||
}
|
||
|
||
fn is_async_block(&self) -> bool {
|
||
self.token.is_keyword(kw::Async) &&
|
||
(
|
||
( // `async move {`
|
||
self.is_keyword_ahead(1, &[kw::Move]) &&
|
||
self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
|
||
) || ( // `async {`
|
||
self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
|
||
)
|
||
)
|
||
}
|
||
|
||
fn maybe_parse_struct_expr(
|
||
&mut self,
|
||
lo: Span,
|
||
path: &ast::Path,
|
||
attrs: &ThinVec<Attribute>,
|
||
) -> Option<PResult<'a, P<Expr>>> {
|
||
let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
|
||
let certainly_not_a_block = || self.look_ahead(1, |t| t.is_ident()) && (
|
||
// `{ ident, ` cannot start a block.
|
||
self.look_ahead(2, |t| t == &token::Comma) ||
|
||
self.look_ahead(2, |t| t == &token::Colon) && (
|
||
// `{ ident: token, ` cannot start a block.
|
||
self.look_ahead(4, |t| t == &token::Comma) ||
|
||
// `{ ident: ` cannot start a block unless it's a type ascription `ident: Type`.
|
||
self.look_ahead(3, |t| !t.can_begin_type())
|
||
)
|
||
);
|
||
|
||
if struct_allowed || certainly_not_a_block() {
|
||
// This is a struct literal, but we don't can't accept them here.
|
||
let expr = self.parse_struct_expr(lo, path.clone(), attrs.clone());
|
||
if let (Ok(expr), false) = (&expr, struct_allowed) {
|
||
self.struct_span_err(
|
||
expr.span,
|
||
"struct literals are not allowed here",
|
||
)
|
||
.multipart_suggestion(
|
||
"surround the struct literal with parentheses",
|
||
vec![
|
||
(lo.shrink_to_lo(), "(".to_string()),
|
||
(expr.span.shrink_to_hi(), ")".to_string()),
|
||
],
|
||
Applicability::MachineApplicable,
|
||
)
|
||
.emit();
|
||
}
|
||
return Some(expr);
|
||
}
|
||
None
|
||
}
|
||
|
||
pub(super) fn parse_struct_expr(
|
||
&mut self,
|
||
lo: Span,
|
||
pth: ast::Path,
|
||
mut attrs: ThinVec<Attribute>
|
||
) -> PResult<'a, P<Expr>> {
|
||
let struct_sp = lo.to(self.prev_span);
|
||
self.bump();
|
||
let mut fields = Vec::new();
|
||
let mut base = None;
|
||
|
||
attrs.extend(self.parse_inner_attributes()?);
|
||
|
||
while self.token != token::CloseDelim(token::Brace) {
|
||
if self.eat(&token::DotDot) {
|
||
let exp_span = self.prev_span;
|
||
match self.parse_expr() {
|
||
Ok(e) => {
|
||
base = Some(e);
|
||
}
|
||
Err(mut e) => {
|
||
e.emit();
|
||
self.recover_stmt();
|
||
}
|
||
}
|
||
if self.token == token::Comma {
|
||
self.struct_span_err(
|
||
exp_span.to(self.prev_span),
|
||
"cannot use a comma after the base struct",
|
||
)
|
||
.span_suggestion_short(
|
||
self.token.span,
|
||
"remove this comma",
|
||
String::new(),
|
||
Applicability::MachineApplicable
|
||
)
|
||
.note("the base struct must always be the last field")
|
||
.emit();
|
||
self.recover_stmt();
|
||
}
|
||
break;
|
||
}
|
||
|
||
let mut recovery_field = None;
|
||
if let token::Ident(name, _) = self.token.kind {
|
||
if !self.token.is_reserved_ident() && self.look_ahead(1, |t| *t == token::Colon) {
|
||
// Use in case of error after field-looking code: `S { foo: () with a }`.
|
||
recovery_field = Some(ast::Field {
|
||
ident: Ident::new(name, self.token.span),
|
||
span: self.token.span,
|
||
expr: self.mk_expr(self.token.span, ExprKind::Err, ThinVec::new()),
|
||
is_shorthand: false,
|
||
attrs: ThinVec::new(),
|
||
id: DUMMY_NODE_ID,
|
||
is_placeholder: false,
|
||
});
|
||
}
|
||
}
|
||
let mut parsed_field = None;
|
||
match self.parse_field() {
|
||
Ok(f) => parsed_field = Some(f),
|
||
Err(mut e) => {
|
||
e.span_label(struct_sp, "while parsing this struct");
|
||
e.emit();
|
||
|
||
// If the next token is a comma, then try to parse
|
||
// what comes next as additional fields, rather than
|
||
// bailing out until next `}`.
|
||
if self.token != token::Comma {
|
||
self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
|
||
if self.token != token::Comma {
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
match self.expect_one_of(&[token::Comma],
|
||
&[token::CloseDelim(token::Brace)]) {
|
||
Ok(_) => if let Some(f) = parsed_field.or(recovery_field) {
|
||
// Only include the field if there's no parse error for the field name.
|
||
fields.push(f);
|
||
}
|
||
Err(mut e) => {
|
||
if let Some(f) = recovery_field {
|
||
fields.push(f);
|
||
}
|
||
e.span_label(struct_sp, "while parsing this struct");
|
||
e.emit();
|
||
self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
|
||
self.eat(&token::Comma);
|
||
}
|
||
}
|
||
}
|
||
|
||
let span = lo.to(self.token.span);
|
||
self.expect(&token::CloseDelim(token::Brace))?;
|
||
return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
|
||
}
|
||
|
||
/// Parses `ident (COLON expr)?`.
|
||
fn parse_field(&mut self) -> PResult<'a, Field> {
|
||
let attrs = self.parse_outer_attributes()?;
|
||
let lo = self.token.span;
|
||
|
||
// Check if a colon exists one ahead. This means we're parsing a fieldname.
|
||
let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| {
|
||
t == &token::Colon || t == &token::Eq
|
||
}) {
|
||
let fieldname = self.parse_field_name()?;
|
||
|
||
// Check for an equals token. This means the source incorrectly attempts to
|
||
// initialize a field with an eq rather than a colon.
|
||
if self.token == token::Eq {
|
||
self.diagnostic()
|
||
.struct_span_err(self.token.span, "expected `:`, found `=`")
|
||
.span_suggestion(
|
||
fieldname.span.shrink_to_hi().to(self.token.span),
|
||
"replace equals symbol with a colon",
|
||
":".to_string(),
|
||
Applicability::MachineApplicable,
|
||
)
|
||
.emit();
|
||
}
|
||
self.bump(); // `:`
|
||
(fieldname, self.parse_expr()?, false)
|
||
} else {
|
||
let fieldname = self.parse_ident_common(false)?;
|
||
|
||
// Mimic `x: x` for the `x` field shorthand.
|
||
let path = ast::Path::from_ident(fieldname);
|
||
let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
|
||
(fieldname, expr, true)
|
||
};
|
||
Ok(ast::Field {
|
||
ident: fieldname,
|
||
span: lo.to(expr.span),
|
||
expr,
|
||
is_shorthand,
|
||
attrs: attrs.into(),
|
||
id: DUMMY_NODE_ID,
|
||
is_placeholder: false,
|
||
})
|
||
}
|
||
|
||
fn err_dotdotdot_syntax(&self, span: Span) {
|
||
self.struct_span_err(span, "unexpected token: `...`")
|
||
.span_suggestion(
|
||
span,
|
||
"use `..` for an exclusive range", "..".to_owned(),
|
||
Applicability::MaybeIncorrect
|
||
)
|
||
.span_suggestion(
|
||
span,
|
||
"or `..=` for an inclusive range", "..=".to_owned(),
|
||
Applicability::MaybeIncorrect
|
||
)
|
||
.emit();
|
||
}
|
||
|
||
fn err_larrow_operator(&self, span: Span) {
|
||
self.struct_span_err(
|
||
span,
|
||
"unexpected token: `<-`"
|
||
).span_suggestion(
|
||
span,
|
||
"if you meant to write a comparison against a negative value, add a \
|
||
space in between `<` and `-`",
|
||
"< -".to_string(),
|
||
Applicability::MaybeIncorrect
|
||
).emit();
|
||
}
|
||
|
||
fn mk_assign_op(&self, binop: BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ExprKind {
|
||
ExprKind::AssignOp(binop, lhs, rhs)
|
||
}
|
||
|
||
fn mk_range(
|
||
&self,
|
||
start: Option<P<Expr>>,
|
||
end: Option<P<Expr>>,
|
||
limits: RangeLimits
|
||
) -> PResult<'a, ExprKind> {
|
||
if end.is_none() && limits == RangeLimits::Closed {
|
||
Err(self.span_fatal_err(self.token.span, Error::InclusiveRangeWithNoEnd))
|
||
} else {
|
||
Ok(ExprKind::Range(start, end, limits))
|
||
}
|
||
}
|
||
|
||
fn mk_unary(&self, unop: UnOp, expr: P<Expr>) -> ExprKind {
|
||
ExprKind::Unary(unop, expr)
|
||
}
|
||
|
||
fn mk_binary(&self, binop: BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ExprKind {
|
||
ExprKind::Binary(binop, lhs, rhs)
|
||
}
|
||
|
||
fn mk_index(&self, expr: P<Expr>, idx: P<Expr>) -> ExprKind {
|
||
ExprKind::Index(expr, idx)
|
||
}
|
||
|
||
fn mk_call(&self, f: P<Expr>, args: Vec<P<Expr>>) -> ExprKind {
|
||
ExprKind::Call(f, args)
|
||
}
|
||
|
||
fn mk_await_expr(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
|
||
let span = lo.to(self.prev_span);
|
||
let await_expr = self.mk_expr(span, ExprKind::Await(self_arg), ThinVec::new());
|
||
self.recover_from_await_method_call();
|
||
Ok(await_expr)
|
||
}
|
||
|
||
crate fn mk_expr(&self, span: Span, kind: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
|
||
P(Expr { kind, span, attrs, id: DUMMY_NODE_ID })
|
||
}
|
||
|
||
pub(super) fn mk_expr_err(&self, span: Span) -> P<Expr> {
|
||
self.mk_expr(span, ExprKind::Err, ThinVec::new())
|
||
}
|
||
}
|