After installing Windows SDK 7.1 alongside 7.0A and restarting Visual Studio 2010 there was no change in the MSDataSetGenerator output from the XSD file. I went out into the garden for 15 minutes and pulled out some weeds, came back, deleted all output files (again!) and did a 'Run Custom Tool' on all XSD files and rebuilt. Now it's working.
So as usual, what's the lesson? There is some relationship between the Windows SDKs that are installed and Visual Studio 2010 (and the MSDataSetGenerator tool), but lord knows what it is. So it only took 5 hours to get a clean compile. I hadn't previously noticed that xsd.exe <http://msdn.microsoft.com/en-us/library/x6c1kb0s.aspx> had a /enableLiqDataSet (/eld) switch which generated generic types. I was surprised to find it on the old v6.0 SDK utility as well, thinking it would have come in later versions. Greg
