var_spec = xrealloc (var_spec, sizeof (*var_spec) * (idx + 1));
/* xrealloc (unlike realloc) doesn't initialise its memory to 0 */
var_spec = xrealloc (var_spec, sizeof (*var_spec) * (idx + 1));
/* xrealloc (unlike realloc) doesn't initialise its memory to 0 */