qmake platform scopes

A standard c++ qmake-based library is developed for Win32, Mac, and Linux. In the qmake project file, the platform-dependent sources are included like this:

win32 {
     SOURCES += WinSystem.cpp
     HEADERS += WinSystem.h
 }

macx {
     SOURCES += MacSystem.cpp
     HEADERS += MacSystem.h
}

unix {
     SOURCES += LinuxSystem.cpp
     HEADERS += Linu开发者_如何学GoxSystem.h
}

Now on OS X both unix and macx are defined, so the Linux files are also included and cause error! What is the solution to this?

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You can negate and combine blocks, so in unix but not in mac would be:

unix:!macx {
  SOURCES += LinuxSystem.cpp
  HEADERS += LinuxSystem.h
}