Should you migrate a project to C++11?

Question

I have been trying to get our team to migrate a large C++ project to VS2012 from VS2008. I want to do it mostly because I want to start using C++11 and the IDE is much nicer. So my reasons are somewhat selfish.

My team lead is pushing back because he doesn't see the business case for the migration, citing that most performance improvement features we'll get with C++11 we already have with BOOST and other libraries. He also says that this will require changing runtimes on all of our platforms which may change certain behavior. Which would mean we would need to retest on all of the servers that we have deployed to.

The first argument I somewhat understand, although I believe C++11 code will be much cleaner than using BOOST (again not a great business case).

The argument about using different runtimes I don't understand. What runtimes do a native C++ application use? This is not VC++. Would his concern be just that the STL won't be exactly the same implementation?

I don't see what the issue there would be. Is there something I am missing? Are there any other good arguments for migrating that I should cite to help my case?

Answer 1

• All 3rd party libraries need to be built with the new compiler
• Code might currently be unknowingly reliant on undefined behavior, a new compiler might do something totally different for UB than the current one (and cause problems)

Performance won't change much because you wouldn't have been coding in C++11 style (basically, lots of stuff is passed by value where before it would not have been). If your code base has a lot of...

std::vector<Blah> func(std::vector<Asdf> v); // notice all the pass by value

... C++11 could be a great performance improvement. But in C++98/03 you just wouldn't do that.

You need to lower the barrier to entrance for your team lead. Do the migration yourself and smoke test your product. Then show it to him. After that, here are abstract reasons to upgrade:

• C++11 style is less code and simpler
• VS2012 has the C++11 standard library additions - you can stop hand rolling 50 bug ridden replacements
• Programmers want to work using a modern language and modern tools. This will spark a company wide resurgence of learning and best practices which will improve code quality, employee retention, employee continuing education, etc
• It's a delicate balance when to do this sort of upgrade. If you do it too often you're spending money without gaining any business advantage. If you do it too infrequently you're dealing with so much legacy tech and legacy code that maintenance can become a nightmare. When a significant language change comes, that you will ultimately move to, it's best to do it sooner than later (and btw, this isn't particularly soon) - otherwise you just keep accumulating what will later be considered legacy code. Moving to a new compiler for new tools often isn't worth it. Moving for an important language upgrade usually is worth it.

Whether any of that is compelling to your team lead is beyond me. Good luck though

Answer 2

VS2012 is so last year, obsolete already, so good Microsoft replaced it after only 1 year of use, criticisms, eye-blinding whiteness, and ALL CAPS!

But considering that you can build a VS2008 project in the newer IDEs means you can upgrade today to VS2013 and work on upgrading the project to the VS2013 tooling over time.

Your TL is correct though, an upgrade requires a complete re-test, but if you have time between adding features then it is possible to fit such a large test in.

I'd say the main aspect of upgrading is just to keep up to date, its not such a big deal today but in another 5 years time your old VS2008 builds might start to hold you back (as I know having recently upgraded a VS2002 project to 2010), its never a good idea to get so far behind as the longer you leave it, the greater the effort in the upgrade that you will eventually have to do. That's the real reason to do it - chances that Microsoft will not support 2008 builds in the next version, and older IDEs won't run on Windows 9, get greater every year. Best to fix this problem while you have time.