[QGIS-Developer] QGIS & PROJ 6 & SAGA

[Even Rouault]

William,

> I must then build and include both PROJ 6 and PROJ.4 in the QGIS package.

Caution...

> There is no option to build SAGA without PROJ, but I could hack the
> makefiles to skip it.  Or I could build it with the old PROJ and just not
> include those modules in the QGIS package.

>From https://packages.debian.org/sid/saga , I see that SAGA has a dependency 
to both GDAL and PROJ. If your GDAL is a GDAL 3, it must be built against PROJ 
6. If you build SAGA against GDAL 3 and PROJ 4 or 5, then SAGA will 
effectively link against 2 different PROJ versions. This is a perfect recipee 
for potential runtime crashes in SAGA depending on how lucky/unlucky you are 
regarding the order into which libraries and symbols are loaded and resolved.

Even

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