How do I get Mono to use the right 'ToolsVersion'?

Question

XBuild Engine Version 12.0
Mono, Version 3.2.8.0

I'm trying to build my C# solution in XBuild. It builds absolutely fine in Windows, but not on Ubuntu. I get the following errors:

warning : Project has unknown ToolsVersion '14.0'. Using the default tools version '4.0' instead.
Target GetFrameworkPaths:
/usr/lib/mono/4.5/Microsoft.Common.targets:  warning : TargetFrameworkVersion 'v4.5.2' not supported by this toolset (ToolsVersion: 4.0).
error CS0246: The type or namespace name 'RedditSharp' could not be found. Are you missing an assembly reference?
error CS0246: The type or namespace name `IReadOnlyCollection' could not be found. Are you missing an assembly reference?

and similar. I have added RedditSharp.dll to the GAC, so I don't know why it can't find it, and I certainly don't know why it can't find IReadOnlyCollection. I have a suspicion that it's all because I can't use ToolsVersion 14.0.

Does anybody know anything about building C# on Linux? What am I doing wrong?

Answer 1

14 means MSBuild 14, which is part of Visual Studio 2015. Usually Mono xbuild only supports the latest Visual Studio release after a while. So you either wait till it is updated, or hack xbuild if you like.

Another workaround is to convert your projects to MSBuild version 12