Unit Tests Skipped
This seems overly complicated. You could simply use if(WIN32) add_definitions... from what I can tell setting it even when minmax isn't a macro has no downside and is in fact what we do in all other code maintained by KDE from what I can see.
Doesn't this set it for consuming code? If so I don't think that is right, should only be set in cmakelists.txt. There isn't a single library where we force nominmax for consumers, even when we set it for ourselves in e.g. a cpp.
Hey, I've been waiting almost a year, what's the problem with my patch, why isn't it accepted? As for NOMINMAX, as you need this you must set this. Or make this "don't expose windows.h in qpipe.h, find another way to get HANDLE" (from TODO file)
For example MinGW has its own windows.h. So, probably, NOMINMAX is not needed for MinGW.
For example, in our project, #include <QtCrypto> is the only one that requires the NOMINMAX macro. Therefore, if QtCrypto is the source of the problem, then it should be solved on the QCA side.