1. Method executed by a computer system for automatically merging changes applied to a first modified program code of a program code and to a second modified program code of the program code, both modified program codes being electronically coded and comprising one or more items, the items being items of a specific programming language; the method comprising the steps of determining from each of the program code, the first modified program code and the second modified program code a respective data structure by programming language dependent parsing of the program code, the first modified program code and the second modified program code, thereby obtaining a syntax information of the program code and the first and second modified program code; determining a first data structure difference between the data structure of the program code and the data structure of the first modified program code by comparing items X i in the data structure of the program code with items Y j in the data structure of the first modified program code and identifying items Y m ′ for which no equivalent in the data structure of the program code can be identified, the first data structure difference comprising the items Y m ′; determining a second data structure difference between the data structure of the program code and the data structure of the second modified program code by comparing items X i in the data structure of the program code with items Z j in the data structure of the second modified program code and identifying items Z k ′ for which no equivalent in the data structure of the program code can be identified, the second data structure difference comprising the items Z k ′; generating a final program code by including at least one of the items Y m ′ and/or Z k ′ in the program code.