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Remove the parser snapshot hack.

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laurent
2017-11-01 06:45:34 +00:00
parent 0d7285393f
commit 175cfbf129
1 changed files with 16 additions and 40 deletions
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56
src/libsyntax/parse/parser.rs
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@@ -3154,47 +3154,23 @@ impl<'a> Parser<'a> {
// Parse: `for <src_pat> in <src_expr> <src_loop_block>` // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
let pat = self.parse_pat()?; let pat = self.parse_pat()?;
// Save the state of the parser before parsing 'in'. if !self.eat_keyword(keywords::In) {
let parser_snapshot_before_in = self.clone(); let in_span = self.prev_span.between(self.span);
match self.expect_keyword(keywords::In) { let mut err = self.sess.span_diagnostic
Ok(()) => { .struct_span_err(in_span, "missing `in` in `for` loop");
let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; err.span_label(in_span, "expected `in` here");
let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?; err.span_suggestion_short(in_span, "try adding `in` here", " in ".into());
attrs.extend(iattrs); err.emit();
let hi = self.prev_span;
Ok(self.mk_expr(
span_lo.to(hi),
ExprKind::ForLoop(pat, expr, loop_block, opt_ident),
attrs))
}
Err(mut in_err) => {
let parser_snapshot_after_in = self.clone();
// Rewind to before attempting to parse the 'in'.
mem::replace(self, parser_snapshot_before_in);
match self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None) {
Ok(_) => {
// Successfully parsed the expr which means that the 'in' keyword is
// missing, e.g. 'for i 0..2'
in_err.cancel();
let in_span = parser_snapshot_after_in.prev_span
.between(parser_snapshot_after_in.span);
let mut err = self.sess.span_diagnostic
.struct_span_err(in_span, "missing `in` in `for` loop");
err.span_label(in_span, "expected `in` here");
err.span_suggestion_short(in_span, "try adding `in` here", " in ".into());
Err(err)
}
Err(mut expr_err) => {
// Couldn't parse as an expr, return original error and parser state.
expr_err.cancel();
mem::replace(self, parser_snapshot_after_in);
Err(in_err)
}
}
}
} }
let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
attrs.extend(iattrs);
let hi = self.prev_span;
Ok(self.mk_expr(
span_lo.to(hi),
ExprKind::ForLoop(pat, expr, loop_block, opt_ident),
attrs))
} }
/// Parse a 'while' or 'while let' expression ('while' token already eaten) /// Parse a 'while' or 'while let' expression ('while' token already eaten)