Resolution of FSharp.Core breaks F# Formatting

[tpetricek]

Most of the projects I manage still use FCS version 44 via F# Formatting. I just tried to update one of them and F# Formatting fails when processing XML documentation with the following:

[0 sec] Resolving assembly: FSharp.Compiler.Service.resources, Version=0.0.57.0, Culture=en-US, PublicKeyToken=null
[0 sec] Resolving assembly: FSharp.Compiler.Service.resources, Version=0.0.57.0, Culture=en-US, PublicKeyToken=null
[0 sec] Resolving assembly: FSharp.Compiler.Service.resources, Version=0.0.57.0, Culture=en, PublicKeyToken=null
[0 sec] Resolving assembly: FSharp.Compiler.Service.resources, Version=0.0.57.0, Culture=en, PublicKeyToken=null
[0 sec] **** error: Problem reading assembly 'FSharp.Core, Version=4.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a': Error opening binary file 'C:\Users\Tomas\AppData\Local\Temp\FSharp.Core.dll':     File 'C:\Users\Tomas\AppData\Local\Temp\FSharp.Core.optdata' not found alongside FSharp.Core
[0 sec] **** error: Error opening binary file 'C:\Users\Tomas\AppData\Local\Temp\FSharp.Core.dll': File 'C:\Users\Tomas\AppData\Local\Temp\FSharp.Core.optdata' not found alongside FSharp.Core
[0 sec] **** error: File 'C:\Users\Tomas\AppData\Local\Temp\FSharp.Core.optdata' not found alongside FSharp.Core
[0 sec] **** stopping due to critical errors
System.Exception: **** stopped due to critical errors
   at FSharp.MetadataFormat.MetadataFormat.Generate(FSharpList`1 dllFiles, String outDir, IEnumerable`1 layoutRoots, FSharpOption`1 parameters, FSharpOption`1 namespaceTemplate, FSharpOption`1 moduleTemplate, FSharpOption`1 typeTemplate, FSharpOption`1 xmlFile, FSharpOption`1 sourceRepo, FSharpOption`1 sourceFolder, FSharpOption`1 publicOnly, FSharpOption`1 libDirs, FSharpOption`1 otherFlags, FSharpOption`1 markDownComments, FSharpOption`1 urlRangeHighlight) in c:\Tomas\Public\FSharp.Formatting\src\FSharp.MetadataFormat\Main.fs:line 846
   at <StartupCode$FSI_0004>.$FSI_0004.main@()

A workaround is to find the right FSharp.Core.dll together with the optdata and sigdata files and place them alongside the dll (or somewhere where they can be found).

Is that an intentional change? (I'd be ok with that, but the fact that this requires sigdata & optdata files is a bit silly.)

[tpetricek]

And I get another error when I try to use F# Interactive - the way this worked in F# Compiler service before. The error message is not very useful:

System.Exception: Error creating evaluation session
   at Microsoft.FSharp.Compiler.Interactive.Shell.FsiEvaluationSession..ctor(FsiEvaluationSessionHostConfig fsiConfig, String[] argv, TextReader inReader, TextWriter outWriter, TextWriter errorWriter) in C:\GitHub\fsharp\FSharp.Compiler.Service\src\fsharp\fsi\fsi.fs:line 2401
   at FSharp.Literate.FsiEvaluator..ctor(FSharpOption`1 options) in c:\Tomas\Public\FSharp.Formatting\src\FSharp.Literate\Evaluator.fs:line 117
   at FSI_0003.Formatters.createFsiEvaluator(String root, String output) in C:\Tomas\Public\Foogle.Charts\docs\tools\formatters.fsx:line 81

[tpetricek]

I'm downgrading to F# Formatting version that referenced FCS v44.

Breaking changes like these are pretty unfortunate :-(. It would be great to add a test that updates ProjectScaffold to the latest FCS and makes sure that everything works there.

[tpetricek]

OK - so the second error disappears after I updated to FCS v59. It still requires FSharp.Core.dll with optdata and sigdata, but at least I got it to work: fsprojects/FSharp.Formatting@143ec25

[fsgit]

We need an issue on this.

[fsgit]

Documentation on FSharp.Core has been added. Closing this as the need for optdata/sigdata is now documented. If you want to use a different SDK location for FSharp.Core then it should be possible to add an explicit reference.