I have .Net framework v4.0.30319 SP1Rel and visual studio 2010 v 10.0.40219.1 SP1Rel (data taken from about dialog in VS).
.Net 4.0 is available here http://referencesource.microsoft.com/netframework.aspx but not sure which specific version that is, and whether it is compatible with my setup. I did download the source a month or two back but I couldn’t step into the framework source (no source available message). I read around at the time and it seemed to be due to updates for VS (and presumably the installed framework binaries) superseding the source version.
Before I try downloading again, could someone please confirm whether the source is now in line with and compatible with the latest versions. If not, is there an alternative (perhaps 3rd party) tool that allows stepping into the source?
EDIT: OK, just saw this http://social.msdn.microsoft.com/Forums/en-US/refsourceserver/thread/41388c7b-582b-4e3f-8178-3d38a3c99639 and this does indicate you cannot use the current source code?
To answer the second part, the professional version of .NET Reflector allows you to step into assemblies for which you do not have the source (including the .NET framework) while you debug your code. It will automatically decompile the assemblies and give you line-by-line debugging support on the decompiled code.
The latest version of Resharper may also offer a similar feature.
Of course, you won’t get the nice variable names and comments that you get when using the reference source.