eval.c:5637
static VALUE
eval_under(under, self, src, file, line)
    VALUE under, self, src;
    const char *file;
    int line;
{
    VALUE args[4];

    if (ruby_safe_level >= 4) {
	StringValue(src);
    }
    else {
	SafeStringValue(src);
    }
    args[0] = self;
    args[1] = src;
    args[2] = (VALUE)file;
    args[3] = (VALUE)line;
    return exec_under(eval_under_i, under, under, args);
}
