VS2015/F#4.0 installation not supported on Windows

[rneatherway]

As reported by @xenocons at fsprojects/zarchive-fsharpbinding#1019:

To reproduce the issue,

Create a .fsx file somewhere else, and put the contents as:

#if INTERACTIVE
#I @"C:\Users\user\Documents\Visual Studio 2013\Projects\test\";;
#endif

Save this file, and close emacs, then load emacs again, then load this file, you will see fsautocomplete.exe crash with something like the following:

Unhandled Exception: System.Exception: Exception when getting check options for 'c:\Users\user\Desktop\test.fsx'
.Details: System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Build.Framework, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
File name: 'Microsoft.Build.Framework, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
   at Microsoft.FSharp.Control.AsyncBuilderImpl.commit[a](Result`1 res)
   at Microsoft.FSharp.Control.CancellationTokenOps.RunSynchronously[a](CancellationToken token, FSharpAsync`1 computation, FSharpOption`1 timeout)
   at Microsoft.FSharp.Control.FSharpAsync.RunSynchronously[T](FSharpAsync`1 computation, FSharpOption`1 timeout, FSharpOption`1 cancellationToken)
   at FSharp.CompilerBinding.LanguageService.GetScriptCheckerOptions(String fileName, String projFilename, String source) in C:\Users\user\.emacs.d\fsharpbinding\FSharp.CompilerBinding\LanguageService.fs:line 299

Additionally, using fsautocomplete.exe and parsing the above file will cause the same exception.

I think it could perhaps be that the version 12 of the framework stuff is not in VS2015's version of F#? I tried this from a fresh elpa install of fsharp-mode.

Edit: Now that i think about it, this is probably due to CompilerServices not using .NET 4.6 yet?

[rneatherway]

Right, that is correct. FSAC doesn't currently support F# 4.0 and/or VS 2015. We are looking at how best to do this. It's difficult because other users of msbuild (e.g. Visual Studio and xbuild on Mono) get to distribute their own installation of msbuild and target files and don't need to worry about supporting different installations.

@xenocons please feel free to continue the conversation here. I would be very interested to hear any ideas you have for resolving this.

[rneatherway]

Fixed by #57. @xenocons the next release of fsharp-mode should fix this.