Compiling Cling with VS2017, Unsupported/Untested error ok to work around?

Hi all. Trying to get started with Cling. Had issues with MSYS2 (checking in JIRA shortly), so I tried VS2017.

Line 370 for tools/cling/lib/Utils/PlatformWin.cpp has a preprocessor error directive, literally #error "Unsupported/Untested _MSC_VER"

One option I saw is to go in and comment out the error and accept it hasn’t been tested, or install the VS2015 build chain with VS2017.

For those who work with Windows and Visual Studio, what would you recommend? This work is just for hobby/personal usage.

Hi Christopher,

Our Windows expert, @bellenot, is on his deserved vacation at the moment. He’ll let you know the answer when he is back, in about two weeks from today! (All I can say is “try VC2015, that might not completely work but it will get you closest”.)

Cheers, Axel.

Thanks @Axel! I hope @bellenot is enjoying his rest.

Do you know if there are a few other Windows users of cling/LLVM? I tried the Jupyter cling kernel last night, and it’s very Unix-bound. I’ve found some other things, and if Windows isn’t a concern at all, then it doesn’t seem worth is to investigate and submit the bugs discovered.

We have Windows users (with patches that we are moving into cling as time allows). We de need to get cling to work on Windows.

Would it help if I submitted bugs in JIRA for issues I find? I don’t really know enough about it all to dive into “Here’s the problem, here’s the fix.” But I can hopefully give some basic information.

Thanks for the offer! We have a pretty good idea what’s missing / currently broken, and we have a series of patches / contributions that we need to move into cling. So instead of Jira tickets it would probably be more relevant for us to hear from time to time (whenever you see my colleague Bertrand Bellenot merging patches from Mr “Frederich Munch”) whether things got better or worse on your side.

Cheers, Axel


FYI, I have a patch for Visual Studio 2017. So it should be fixed soon.

Cheers, Bertrand.

Welcome back @bellenot,

What is the ETA on your patch?

I’m a Java programmer by trade. I play around with C++ every now and then as a hobbyist.

Being of the opinion that jshell is the absolute best thing about JDK 9, I was so stoked when I googled for “c++ REPL” the other day, and discovered cling! Thanks for making such a neat tool available :+1:

I’m also using VS 2017 (Community edition). I just encountered the same error the OP is reporting.

Just as an aside — On my 7 year old Windows 7 personal laptop (8GB ram, 2.13 GHz i3 CPU) it wasn’t until the very end of like a 3+ hour build that the _MSC_VER test failed the build. Would there be any value in testing for the compiler version at the top of the build and failing earlier?

Many thanks :+1:


Thanks! It should go in this week.

I’ll check what can be done, but the problem is not like for prerequisites, it only happens with newer version of Visual Studio, not yet defined in the source code (unrelated to the build system)

Cheers, Bertrand.

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