[geos-devel] Exception Issues

[Norman Vine]

David Blasby writes:
> 
> I'm not 100% sure of the exact nature of the problem, but 
> http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=37933
> has some more technical details.
> 
> To summarize the article, the problem is not with the C++ exception 
> mechanism; it works just fine if you link your program to libc++.  The 
> problem is when you link the main program to libc (which doesnt 
> understand c++ exception handling).  When the c++ code throws and 
> exception that has to unwind the stack (ie. leave the function that 
> threw it) a problem occurs because the default unwind mechinism in
> libc is SIGABRT (terminate the program).
> 
> If the same program were linked to libc++, then the default unwind 
> mechanism would handle the exception properly.
> 
> Anyways, read the article and see if my summary is accurate.
> 
> This isnt an issue in most program - a C program that is using libgeos 
> would link it in at compile time.  This will cause it to link to libc++ 
> not libc.
> 
> In postgresql, it is compiled and linked to libc.  When it want to load 
> in postgis, it just openes up the .so at runtime (not compile time).

This should be easily solved by modifying the Postgresql link step 
to link as C++ instead of 'C'.  

This is allowable in that C++ is by the 'standard' defined as a 
superset of C

Note I believe that this should only be necessary for the PostGIS
DLL 

Norman