I would go for method two, http://log4qt.sourceforge.net/ has an easy guide, but it seems like you did that. Make sure the paths exists, and the case is right(my log4qt.pri is all lowercase). Make sure that your slashes are the correct way, it's weird how your error:

Qt Code: 
  1. ..\..\librarys\log4qt\src\/spi/filter.h
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has \ during your path and / during the path to the library.

My sample include is

Qt Code: 
  1. include(./Utilities/log4qt/src/log4qt/log4qt.pri)
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It's probably a typo, so go over everything carefully.