Many auto-generated .Designer files in Visual Studio contain a boiler-plate like the one below.
'------------------------------------------------------------------------------
' <auto-generated>
' This code was generated by a tool.
' Runtime Version:4.0.30319.18052
'
' Changes to this file may cause incorrect behavior and will be lost if
' the code is regenerated.
' </auto-generated>
'------------------------------------------------------------------------------
By default, we have always checked these designer files into source control. This turns out to be in line with Microsoft's recommendation: "custom tools are run at design-time and not at build-time, and therefore the dependent file needs to be checked into source control". Unfortunately, most SO questions out there ask whether or not these designer files should be checked in or not (for example) and neglect the issue of the continually changing Runtime Version and it's affect on source control.
Dan Brackett touches on the issue in this question only his question is specific to the solution of syncing all developers to the same version. This seems like an intimidating task especially, as pointed out by responders to the referenced question, contractors get involved. Interestingly, Dan also comments that this is no longer an issue in VS 2010. However, it appears to be an issue in VS 2012. Perhaps there is a config value to turn it off?
It's a challenge when multiple developers, each with differing .Net versions, check in these auto-generated files with an updated Runtime Version. This fixes it for them but then the other developers show outdated/changed files.
One option is to allow the files to stay outdated with out checking in changes but this makes it difficult for developers to trust the source control status of a project or file.
Another option is to ignore them with your source control software but these files do change legitimately and ignoring them would risk losing important updates or miss having valid changes checked back in to the repository.
Any other options out there for us?
UPDATE: To clarify further, we do not want to have developers targeting different .Net versions such as 3.5 vs 4.0. Our concern is not in the "4.0.30319" part of the version, it's in the last maintenance segment that changes with auto updates to Windows and Visual Studio.