Managing bigint memory

new_ast.cpp

@@ -319,7 +319,7 @@ function Ast_Atom *
 ast_int(Token *pos, BigInt val){
   AST_NEW(Atom, VALUE, pos, AST_EXPR | AST_ATOM);
   result->type = untyped_int;
-  bigint_init_bigint(&result->big_int_val, &val);
+  result->big_int_val = bigint_copy(pctx->perm, &val);
   return result;
 }