Why does Visual Studio 2010 convert my projects?

Why does Visual Studio 2010 convert my projects?

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Luau in Hawaii Hi, I am Richa Prasad and I am the Program Manager for the Project System team. This means that I work on many features for managing projects and solutions. One such feature is the conversion process. We have recently received many requests for making the conversion process optional; i.e. supporting the ability to open old Visual Studio version projects in a newer Visual Studio version without the need to convert. We call this round-tripping. This blog post is an attempt to capture the questions that have been asked and our answers to them.

What is round-tripping?

Round-tripping is the ability to use a current or previous version of Visual Studio to target a platform that is supported by both versions of VS. For example, with round-tripping, you can open projects from a previous version of VS in a newer IDE without the need for conversion, thus allowing you to work side-by-side on old and upgraded projects.

Why is round-tripping not supported in VS2010?

The difficulty in supporting round-tripping does not lie in the solution and project files but rather the files that they reference. There are two key problems when trying to address round-tripping of projects and solutions between versions of Visual Studio:

1. Correctly handling projects, solutions and the files they reference when operating in a newer environment.

For instance, Visual Studio runs custom tools such as single file generators for designers in order to output code representing the changes made to the designer. Many of these custom tools are upgraded or completely replaced in the newer IDE. During conversion, the IDE knows which custom tools to replace or upgrade. In order to make round-tripping work, VS would need old and new custom tools to understand each other so as to ensure that old and new designers can work side by side. Other than designers, the following files would also be affected: resource editors, wizards, code snippets, item and project templates, diagramming and modeling tools, and many more.

2. Any changes that may be required in the older version of VS to support upgraded file round-tripping and to offer an appropriate user experience where files have been modified (or even upgraded).

Let’s assume that half the projects in a solution have been upgraded to target .NET Framework 4, and half target .NET Framework 3.5. When this solution is opened in VS2008, a key consideration is how VS2008 will deal with projects that target a framework it knows nothing about. Other than such aforementioned multi-targeting considerations, there are also IDE upgrades that need to be accounted for when opening an upgraded solution in an older IDE. For instance, VS2008 will not work with upgraded designers that contain code from VS2010 since it does not recognize the code that has been generated by VS2010 designer custom tools.

I don’t see a lot of difference between my project files. I can hand-edit it back to work with VS2008. Why can’t VS do this for me?

The solution and project files may not have changed significantly but the files that they reference have changed. For instance, if you have designer files in your project, even if you hand-edit the project and solution files to work with an older VS, the designer files will not work.

Does this mean that as long as I don’t use designers, I can manually hand-edit files to do round-tripping?

No. If your projects have undergone a conversion process, their content may no longer be valid in an older VS. For example, during the VS2010 conversion process, test projects are automatically retargeted to target .NET Framework 4. Thus, hand-editing project and solution files to be VS2008 compatible would not enable test projects to once again work in VS2008. Another example is C++ projects where .vcproj, .rules and .vsprops files are replaced during conversion. There are many such changes that happen to files during the conversion process.

What do you recommend to companies that have some developers using VS2008 and some using VS2010?

We recommend keeping your solutions separate – one set of developers can work on one codebase, while another set of developers can work on another codebase.

If I want to evaluate VS2010 on my existing projects, how do you recommend I do that?

We recommend setting up your code in source control or a virtual machine, or creating a backup before conversion. In general, we do offer a backup option in the conversion wizard.

When is round-tripping going to be supported in VS?

We will be seriously considering round-tripping as a feature in the next release. However, we are only in the early stages of planning for the next VS version.

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  • Is there any way that I can convert it back from VS 2010 solution to VS 2008 or 2005 ???

  • Was this not why XML was touted as the solution? You can have some tages in the solution file that VS2010 can understand and then VS2008 can ignore?

  • @southafrica: Please reread the post. It's not about the project file, it's about the source and other files that are referenced by the project. So the problems come from C# and VB, not MSBuild and the project system.

  • @Jasper - We do not support converting your projects back to a previous version. We provide the backup option during conversion for the very reason to save your old version of the projects.

    @southafrica - The difficulty in supporting round-tripping is not with the solution and project files but the files that they reference.

  • This is why we only use the IDE as a source navigator.  The actual build is handled by GNU make (which invokes cl.exe / link.exe).

    No more conversion BS necessary.

  • We started asking for this feature during the Whidbey planning stages, so it's rather disappointing to see that you've not made any effort to make the dependent tools support backwards compatibility. On a large solution I converted (Website, several class libraries, silverlight, WCF, etc), where everything was upgraded to V4, the only things that changed were version numbers, even in designer files.

    Maybe I'm missing something more fundamental, but switching code to (de)serialize these files based upon the version doesn't seem that hard. I doubt many of us even want mixed projects; generally  the entire solution will be in VS2008 format or VS2010 format. What we want is to use the better tool (better intellisense, multi-monitor supoprt, etc), while keeping the solution in supportable format. As it is I only have 1 project that I can upgrade because I need to maintain VS2008 support for the others.

  • It would make life a lot easier if instead of making a backup copy you would convert to a NEW file name and the new file name would have a new extension that is associated with the new program.

    Solution and project files would reflect the version such that extension .slnvXX changes to .slnvYY and .prjvXX to prjvYY

    You don't want the VS 2008 file associations changed to open VS 2008 projects/solution with VS 2010 by default since the only thing you can do in this case is convert.  

    You have to use both for some time while you migrate and some older projects/solutions may not ever be converted and you might still use VS 2008.  

    You only want to open VS 2008 files in VS 2010 to convert and you can manually open the VS 2008 project/solution in VS 2010 to do the conversion.

    Currently you have to manually change the name of the new files and their backups.  This way as you convert and evaluate the new Visual Studio you don't change files in source control the rest of the team are using and you can use both versions.  Now multiply this times 20 or 30 solutions and you might see how this would make life simpler.

  • i do understand its difficult to support previous version,, but forcing the project to be converted is rather severe.

    i tried for a c# project done in vs2008 to be converted, and the wizard says its not able to convert my project to 2010, so now i cant doubleclick on the project file but i have to open it in vs2008 manually....

    so i have vs2010, but i can only use it for new project,,, which is a waste...

    hope some fix will come in shortly...

  • @Farid

    I am curious as to why conversion is failing for your project. Please feel free to contact me at richap @ microsoft.com with details on the uprade report and the project type you are converting.

  • you are pretty :-)

  • I don't think the feature needs to round trip the files.  I think having Visual Studio version n able to read and compile Visual Studio n-1 solutions is the key feature.  I wouldn't expect Visual Studio version n being able to operate on version n + 1 solutions.  I believe this is how Access 2003 worked.  It could work on 2000 and 97 database files and after they were upgraded to the 2k3 format only Access 2003 could understand the format.

  • This is a problem mainly for consultants or very large corporations.  If you can upgrade your projects to VS 2010, I see no problem with doing that.  I think people make this way too nitpicky

  • Hi Richa!

    The company I work for has about 50 developers working on the same project (5 solutions, ~30 projects). We talked about upgrading VS.NET 2008 to 2010 for some of the developers only, who needed to work in .NET 4.

    Unfortunately this means that some projects in the repository will have to be upgraded as well. In order for the rest of the team to work with the same projects this leaves us with the only option to maintain "duplicate" project files (and possible breaking changes in i.e. designers as mentioned).

    This is a cost that might stop our upgrade to VS.NET 2010 and .NET 4.

  • I honestly can't think of one single IDE or "document-driven" product out there that does NOT handle old solutions/projects/documents in a non-destructive way.

    Not being able to open and edit 2008 solutions in 2010 without conversion is slowing our adoption of 2010 down with at least 6 months, maybe a year. It's simply the stupidest "wont support" I've ever encountered as a developer. It's as if the Office Suite would refuse to open .doc without converting to .docx first and then refusing to convert it back again.

    Oh how happy I am, sitting on a 2010 Ultimate license that cannot be used on our existing 500kLOC codebase.

  • It sounds like you're just making up B.S. excuses, and the real reason for this lack of support is to force companies and individual developers to upgrade to VS 2010.  I bet you guys spent days dreaming up reasons why you couldn't support backwards compatibility.

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