Fix parsing of ranges after unary operators

Author: dtolnay

compiler/rustc_parse/src/parser/expr.rs

@@ -605,7 +605,11 @@ impl<'a> Parser<'a> {
 fnparse_expr_prefix_common(&mutself,lo:Span) -> PResult<'a,(Span,P<Expr>)>{
 self.bump();
 let attrs = self.parse_outer_attributes()?;
-let expr = self.parse_expr_prefix(attrs)?;
+let expr = ifself.token.is_range_separator(){
+self.parse_expr_prefix_range(attrs)
+}else{
+self.parse_expr_prefix(attrs)
+}?;
 let span = self.interpolated_or_expr_span(&expr);
 Ok((lo.to(span), expr))
 }