Thanks Dominig,
OpenSUSE is pretty strict when it comes to the quality of the code which gets in their repo and enforce some compiler warnings to to upgraded as error. There are several ways to correct those issues:
1) fix the problem in the source The best and prefer option is to fix the code. These type errors can induce nasty side effect and often are easy to correct.
2) change the compiler option In the make file, select the the required option to ignore the error. If there is no warning from the compiler, OpenSUSE will assume (rightly or wrongly) that you know what you do and you had no choose in keeping such ugliness.
Yes, if I remove -Werror flag under CCFLAGS in src/Makefile, rpm gets generated.
3) use rpmlinrc rpmlint calculate an ugliness marking and if you pass the threshold it fails the package. You can change the ugliness marks allocated to certain type of errors. It's often easier to go around the issue, when possible (not for all warning type) but as bad as solution 2).
I do not know about this tool, I will learn about it.
Conclusion. ------------------ It's often not longer to fix the code once for all. That is the prefer route.
Let me give second review to go for option one.