For some reason this broke compilation for me:

In file included from /usr/include/libudev.h:23,                                                                                                              
                 from /usr/include/libinput.h:35,                                                                                                             
                 from /home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/backends/libinput/context.h:11,                                  
                 from /home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/backends/libinput/connection.cpp:10:
/home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/libkwineffects/version.h:26:14: error: expected unqualified-id before 'unsigned'       
   26 |     uint32_t major() const;                                     
      |              ^~~~~                                                                                                                                    
/home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/libkwineffects/version.h:26:14: error: expected ')' before 'unsigned'                  
   26 |     uint32_t major() const;                                                                                                                           
      |              ^~~~~                                                                                                                                    
/home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/libkwineffects/version.h:26:14: error: expected ')' before 'unsigned'                  
   26 |     uint32_t major() const;                                
      |              ^~~~~                                                
/home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/libkwineffects/version.h:27:14: error: expected unqualified-id before 'unsigned'       
   27 |     uint32_t minor() const;                                       
      |              ^~~~~                                             
/home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/libkwineffects/version.h:27:14: error: expected ')' before 'unsigned'                  
   27 |     uint32_t minor() const;                   
      |              ^~~~~                                                                                                                                    
/home/pmos/build/src/kwin-1236e3e83b90f07f9f09fc0addf8ba0ee8c54dc2/src/libkwineffects/version.h:27:14: error: expected ')' before 'unsigned'
   27 |     uint32_t minor() const;                                                                                                                                                                                                                                                                                          
      |              ^~~~~

I don't understand it though, why does it expect a ) for what seems to be perfectly valid code?

I don't know why that would only cause problems for you, both local builds and CI say it's fine. But the problem is probably caused by the stupid major and minor defines, which would explain the weird error messages

Well my system is a bit weird in that it uses Musl libc rather than glibc, which is probably the cause here. Are major and minor already taken? They're at least quite... Generic names 😅

I still need to get Musl up and running on KDE CI sometimes but we had some issues blocking it...