In 'Leave Management', there is a concept of 'Prefix/ Suffix'. Normally, the companies permit Sundays/ Closed Holidays to be either prefixed or suffixed with leave, but not both. As an example, if an employee takes leave on Monday, Sunday can be permitted as a prefix. And if he is on leave on Saturday, Sunday can be given as suffix. In the present case, the employee has to be on leave from Saturday to Monday (3 days) since he can't have the privilege of having Sunday, both as a prefix & suffix..
But, it all depends on the 'Leave Policy' of a company. If your policy clearly states that the same Sunday/ Holiday can be taken both as a prefix & suffix with leave, no one shall be in a confusion. But you may also need to clarify that Sundays/ Holidays falling within a leave period shall be exempted while calculating the total number of days for which an employee was on leave. This may be an employee friendly policy but, in principle, it negates the definition of the continuity of leave period and is thus not encouraged by organizations.
Clarifying all these aspects with examples in a company's 'Leave Policy' is, therefore, important not only from the employee viewpoint, but also to enable 'Leave Management' by the sanctioning authority & HR.