[osgeo4w-dev] cross compatibility issues: FreeXL / SpatiaLite / GDAL

[a.furieri at lqt.it]

the problem I've identified:
----------------------------
a) spatialite depends on freexl
b) gdal depends on both freexl and spatialite

the current spatialite 3.0.1-2 DLL distributed by
OSGeo4W was linked (inadvertently, I presume) so to
include a static internal copy of the freexl library.

consequently the current gdal 1.9.2-2 DLL available
on OSGeo4W depends on these "static" freexl link
symbols expected to be found within spatialite.dll
and not within freexl.dll, as it would be more
reasonable.

the overall result is that any attempt to rebuild
spatialite.dll in the "right way" (e.g. avoiding to
statically link freexl.lib and depending instead on
freexl.dll) will consequently cause fatal errors
due to unresolved link symbols when loading gdal.dll

e.g. this will make completely impossible starting QGIS;
to make things even worst (if possible) Windows poor
diagnostic messages will be of very little help in
order to identify the real failure cause.
I had a big pain in order to really understand what's
going wrong in my own QGIS test build.

I'm able to foresee only two possible ways to circumvent
this dangerous pitfall:
A) still continuing to build any new version of spatialite.dll
    so to statically link freexl (looks really a ugly workaround)
B) carefully synchronizing the next release of both spatialite
    and gdal (may be 1.10 ?) so to safely switch to a "pure dll"
    approach and thus restoring normality.

bye Sandro

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