[Gdal-dev] Structure member alignment suggestion

[Ray Gardener]

FWIW, I came across a runtime problem when a project uses a different 
structure member alignment (e.g., 4 bytes) than whatever was used to 
build GDAL with (normally 8 bytes in MSVC/Pentium). For example, the 
OGRSpatialReference class will become misinterpreted. Below are the 
current and suggested member layouts:

class CPL_DLL OGRSpatialReference
{
     int         nRefCount;
     OGR_SRSNode *poRoot;
     int         bNormInfoSet;
     double      dfFromGreenwich;
     double      dfToMeter;
     double      dfToDegrees;
     ...
};


Suggested:
     double      dfFromGreenwich;
     double      dfToMeter;
     double      dfToDegrees;
     OGR_SRSNode *poRoot;
     int         nRefCount;
     int         bNormInfoSet;


Another possibility is to enclose structures in

#ifdef MSVC
#pragma(pack, push, 8)
#endif
...
#ifdef MSVC
#pragma(pack, pop)
#endif

Ray