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Error-Unrecognized option: '--preferreduilang' when building WebSharper projects
websharpercompiler

When building WebSharper projects, build fails with the above error. In the output window I can see that the compiler (see below) is called with the --preferreduilang:en-US option, but looks like it doesn't recognize it. I am using Visual Studio Community 2017 Preview Version 15.4.0. Preview 2.0

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1>	C:\Root\Project\NCF\packages\Zafir.FSharp.4.0.188.91-beta10\build\..\tools\WsFsc.exe -o:obj\Debug\NCF.BPP.PowerBI.JSExtension.dll
1>-g
1>--debug:full
1>--noframework
1>--define:DEBUG
1>--define:TRACE
1>--doc:bin\Debug\NCF.BPP.PowerBI.JSExtension.XML
1>--optimize-
1>--tailcalls-
1>-r:C:\Program Files (x86)\Microsoft Visual Studio\Preview\Community\Common7\IDE\PublicAssemblies\FSharp.Core.dll
1>-r:C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5.2\mscorlib.dll
...
1>-r:C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5.2\Facades\System.Xml.XmlSerializer.dll
1>--target:library
1>--warn:3
1>--warnaserror:76
1>--vserrors
1>--preferreduilang:en-US
.

This error also occurs in a project just created from the client-server WebSharper template.

By on 9/12/2017 9:21 PM ()

Thanks for the report!

WebSharper for F# works by replacing the call to fsc.exe to its own wsfsc.exe, which removes WebSharper-specific flags and passes along the rest to FSharp.Compiler.Service, but uses the Microsoft.FSharp.Targets file and the MSBuild task of the system F# installation. This seems a newer feature of the F# compiler itself included with VS 15.4 Preview, not included yet in the version of FCS packaged. I will look into updating it.

Workaround: link a Microsoft.FSharp.Targets file in the project file that is an older one, for example by downloading the FSharp.Compiler.Tools package.

By on 9/13/2017 12:29 AM ()

Just got this error after updating VS. I'm not clear about the fix. I downloaded FSharp.Compiler.Tools, but the problem remains. Can'[t compile anything... :(

By on 10/10/2017 12:48 PM ()

This is how I fixed it: 1) Open NuGet UI at solution level 2) Remove FSharp.Compiler.Tools from all the project's packages in the solution 3) Re-install the latest version of FSharp.Compiler.Tools for the same projects 4) Clean/Rebuild projects

This succeeded for me

By on 10/10/2017 2:31 PM ()

Thanks. Installing a tool chain is new to me. I was reinstalling the newest tool. I needed to select version 4.1.23. Even then, I had to manually adjust some of my *.fsproj files to get it to pick up the new tools...

By on 10/10/2017 3:37 PM ()

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