I'm surprised this wasn't the case before. AFAIK, structs with doubles have been aligned to at least an 8 byte boundary for years. You may need to write a new reader that knows the layout on disk and reconstructs the data. Brian On Wed, Jun 2, 2010 at 9:16 AM, Christian Convey <christian.convey@xxxxxxxxx> wrote: > Are you sure that's a bug in the legalistic sense? IIRC, C and C++ > don't promise any particular memory layout for structs. > > On Wed, Jun 2, 2010 at 11:53 AM, David R. Doucette > <ddoucette@xxxxxxxxxxxxxxxx> wrote: >> We just installed Lucid Lynx a few days ago, and have hit a fatal flaw with >> g++ that has forced us to stop the deployment and roll back the systems we >> could. >> >> Structures in Lucid are now mapping differently than in the past, so we can >> no longer read our own files! Further, if any files are written by code >> produced by the new g++, they are corrupted. >> >> The problem is that doubles are now being mapped onto a boundary divisible >> by 8 rather than a boundary divisible by 4, meaning that offsets change and >> structs get bigger. >> >> I've attached a tar file showing the mapping on Jaunty, Karmic, and Lucid to >> show the change. This is a greatly simplified program that shows the >> problem, but it's happening in all of our C++ programs. >> >> HELP! >> >> System is Ubuntu 10.4 Lucid Lynx 64 bit. >> >> David Doucette >> >
