qmake does not find features file after setting QMAKEFEATURES

[jmalicke]

I have installed Qwt:

/usr/local/qwt-6.1.0/
        features/
          qwt.prf
          qwtconfig.pri
          qwtfunctions.pri

/usr/local/qwt-6.1.0/
        features/
          qwt.prf
          qwtconfig.pri
          qwtfunctions.pri

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I set `QMAKEFEATURES` as according to the docs:

qmake -set QMAKEFEATURES /usr/local/qwt-6.1.0/features

qmake -set QMAKEFEATURES /usr/local/qwt-6.1.0/features

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Sanity-check:

$ qmake -query
    QMAKEFEATURES:/usr/local/qwt-6.1.0/features
    ...

$ qmake -query
    QMAKEFEATURES:/usr/local/qwt-6.1.0/features
    ...

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In my project .pro file I add qwt:

QT += qwt

QT += qwt

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When I build...

$ qmake 
    $ make
    ...
    Project ERROR: Unknown module(s) in QT: qwt

$ qmake 
    $ make
    ...
    Project ERROR: Unknown module(s) in QT: qwt

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I have tried using an environment variable instead:

$ export QMAKEFEATURES=/usr/local/qwt-6.1.0/features
    $ echo ${QMAKEFEATURES}
     /usr/local/qwt-6.1.0/features/
    $ qmake 
    $ make

$ export QMAKEFEATURES=/usr/local/qwt-6.1.0/features
    $ echo ${QMAKEFEATURES}
     /usr/local/qwt-6.1.0/features/
    $ qmake 
    $ make

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And I still get the same problem.

I have tried to direct include the .prf in the .pro file:

include ( /usr/local/qwt-6.1.0/features/qwt.prf )

include ( /usr/local/qwt-6.1.0/features/qwt.prf )

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Same error again.

Why won't qmake pick up the prf file?