How to display all days in a month by SQL Server?

How to display all days in a month by SQL Server?

DECLARE @RepMonth as datetime

SET @RepMonth = '04/01/2015';

WITH DayList (DayDate) AS

(

    SELECT @RepMonth

    UNION ALL

    SELECT DATEADD(d, 1, DayDate)

    FROM DayList

    WHERE (DayDate < DATEADD(d, -1, DATEADD(m, 1, @RepMonth)))

)

SELECT *

FROM DayList