Fixed warnings

src/parser/ast.rs

@@ -7,7 +7,7 @@ use crate::types::HeapCellValueTag;
 use std::cell::{Cell, Ref, RefCell, RefMut};
 use std::fmt;
 use std::hash::{Hash, Hasher};
-use std::io::{Error as IOError};
+use std::io::Error as IOError;
 use std::ops::{Deref, Neg};
 use std::rc::Rc;
 use std::vec::Vec;

src/parser/parser.rs

@@ -958,7 +958,7 @@ impl<'a, R: CharRead> Parser<'a, R> {
     }
 
     fn shift_token(&mut self, token: Token, op_dir: &CompositeOpDir) -> Result<(), ParserError> {
-        fn negate_int_rc(mut t: TypedArenaPtr<Integer>) -> TypedArenaPtr<Integer> {
+        fn negate_int_rc(t: TypedArenaPtr<Integer>) -> TypedArenaPtr<Integer> {
             let i: Integer = (*t).clone();
             let mut data = i.neg();
             TypedArenaPtr::new(&mut data)