Can't build against libgimp-3.0-dev v3.0.0~RC2-1

[ChthonVII]

EDIT: It turns out this (mostly?) boils down to out-of-date build instructions in the readme:

The readme says to do git clone https://github.com/c-koi/gmic-qt.git, which is out-of-date and should instead be git clone https://github.com/GreycLab/gmic-qt.git.

The way to build for gimp 3.0 differs between QMake and CMake. CMake should be told -DGMIC_QT_HOST=gimp3, but QMake should be told HOST=gimp and it will deduce the gimp version by looking at what's installed. This is not documented anywhere.

With the above sorted out, following the Qmake instructions works.

Following the CMake instructions doesn't work. It will complain about missing GmicConfig.cmake. I'm not sure this is due to steps missing from the instructions or a bug in the cmake files. (In any event, my attempts to generate that file by running cmake in the gmic directory only made things worse.)

(I'm deleting original text since what's reported there is explained by cloning the wrong gmic-qt repo.)

[ChthonVII]

Aha!

I was copy/pasting from the readme without paying adequate attention. It says to do git clone https://github.com/c-koi/gmic-qt.git, which is out-of-date and should instead be git clone https://github.com/GreycLab/gmic-qt.git. Using the correct repo works much better.

EDIT: Linker error is explained by using qmake HOST=gimp3 when it should be qmake HOST=gimp. See edit to first post.

(Deleted lengthy console output that's now explained.)