Include geos version at build time in postgis_full_version()

[strk]

I know it's getting complex, but sometimes you have two GEOS versions installed and while "geos-config" (called by ./configure) finds one version, the dynamic linker finds another version.

Another scenario is you simply upgrade GEOS but you built against an older one.

In both cases postgis_full_version() isn't enough to explain why some feature isn't available or some bug is still present.

[robe]

I don't understand this ticket? What is the problem. We have GEOS version in postgis_full_version already and when dynamic linker finds a different version, you can't even load the postgis.so/dll.

[strk]

Some GEOS features are off when you build PostGIS against an older GEOS. After you upgrade GEOS you see the _new_ version reported by postgis_full_version() and can wonder "why don't I have this functionality?"

I've added the build-time version of GEOS into the error message that comes out when you try to access the unavailable functionality, but it's still confusing.

Example (made out):

 $ SELECT ST_SharedPaths(x,y) FROM mytable;
 ERROR: you need GEOS 3.3.0+ for this to work
 $ SELECT postgis_full_version();
 ... GEOS 3.3.8 ...

[robe]

you know my answer to that. I hate having versions that dissable functionality. We wouldn't have this problem if we listened to me. Granted we'd have other problems :)