F# classlib MissingMethodException in 2.0.0-preview2-006391

[AnthonyLloyd]

Steps to reproduce

1. Create a F# classlib referenced by an F# console project
2. Code in the classlib builds fine but throws a MissingMethodException when run

An example I'm working on:
https://github.com/AnthonyLloyd/BenchmarksGame/tree/DotNetCore2preview2Bug

dotnet build succeeds
dotnet run --project .\tester\tester.fsproj fails

Expected behavior

The code builds so I wouldn't expect a missing method exception.

Actual behavior

Unhandled Exception: System.MissingMethodException: Method not found: 'Double FSharpOriginalNBody.test()'. 
 at Program.main@32-1.Invoke(Unit arg00@) 
 at Program.isFasterThan@26-1.Invoke(FSharpFunc`2 measurer) in C:\Users\Ant\src\BenchmarksGame\tester\Program.fs:line 26 
 at Expecto.Performance.timeCompare[a](FSharpFunc`2 f1, FSharpFunc`2 f2) in C:\Users\Ant\src\BenchmarksGame\tester\Performance.fs:line 133 
 at Program.isFasterThanSub[a](FSharpFunc`2 f1, FSharpFunc`2 f2, String format) in C:\Users\Ant\src\BenchmarksGame\tester\Program.fs:line 10 
 at Program.isFasterThan[a](FSharpFunc`2 f1, FSharpFunc`2 f2, String message) in C:\Users\Ant\src\BenchmarksGame\tester\Program.fs:line 25 
 at Program.main(String[] argv) in C:\Users\Ant\src\BenchmarksGame\tester\Program.fs:line 32 

I've checked that a mismatched function name causes a build error.

Environment data

dotnet --info output:

.NET Command Line Tools (2.0.0-preview2-006391) 
 
Product Information: 
 Version: 2.0.0-preview2-006391 
 Commit SHA-1 hash: ef5d4b47c3 
 
Runtime Environment: 
 OS Name: Windows 
 OS Version: 10.0.16215 
 OS Platform: Windows 
 RID: win10-x64 
 Base Path: C:\Program Files\dotnet\sdk\2.0.0-preview2-006391\ 
 
Microsoft .NET Core Shared Framework Host 
 
 Version : 2.0.0-preview2-25407-01 
 Build : 40c565230930ead58a50719c0ec799df77bddee9 

[livarcocc]

@KevinRansom @cartermp

[cartermp]

cc @dsyme as well. @KevinRansom is out this week, so he may not be able to take a look at this.

[enricosada]

@livarcocc is possibile to add an fsharp label to these issues? i'd like to improve the visibility for F# of what's missing/bugged in f# for 2.0.0
Is a bit annoying to find these with search (github ignore the # pratically..)

[dsyme]

@enricosada @cartermp I don't generally debug .NET Core things, but I took a quick look for my own education and noticed that there is no FSharp.Core.dll in

C:\GitHub\misc\BenchmarksGame\tester\bin\Debug\netcoreapp2.0

I would have thought it would exist since FSharp.Core.dll is, I assume, added as a default dependency package of both the F# tester app and the F# library, as mentioned here https://github.com/dotnet/netcorecli-fsc/wiki/How-to-migrate-1.0-projects-to-2.0#changes-in-fsproj

[dsyme]

@enricosada @cartermp (Though I do have tester.runtimeconfig.dev.json which indicates where fsharp.core lives, so that's probably a red herring)

[dsyme]

@cartermp @KevinRansom @enricosada Ugh, I see this valuetype [netstandard]System.Double in the compiled binary - this looks wrong.

.assembly extern netstandard
{
 .publickeytoken = (CC 7B 13 FF CD 2D DD 51 ) // .{...-.Q
 .ver 2:0:0:0
}

and

.method public static valuetype [netstandard]System.Double 
 test() cil managed

[dsyme]

That is, I would expect simple "float64" in these cases. It looks at first sight like the F# compiler hasn't been correctly adjusted to emit primitive types correctly in the presence of the "netstandard" library. I don't know any of the details of this and I don't really understand what's going on

The C# code has the correct signature:

.method public hidebysig static float64 Test() cil managed

[dsyme]

OK, so .NET Core 2.0 adds this new DLL netstandard.dll

packages\netstandard.library\2.0.0-preview2-2540101\build\netstandard2.0\ref\netstandard.dll

This seems to be yet another "mscorlib.dll" and "System.Runtime.dll" but I don't yet understand the rules concerning this. I'm assuming the F# compiler just needs to be updated to understand this special DLL, though I'm unclear about if/how type forwarding works out to ensure these types all add up.

[dsyme]

Here is the full command line being used:

 C:\Program Files\dotnet\sdk\2.0.0-preview2-006470\FSharp\RunFsc.cmd -o:obj\Debug\netstandard2.0\fsharp.dll
 -g
 --debug:portable
 --noframework
 --define:TRACE
 --define:DEBUG
 --define:NETSTANDARD2_0
 --optimize-
 --tailcalls-
 -r:C:\Users\dsyme\.nuget\packages\fsharp.core\4.2.1\lib\netstandard1.6\FSharp.Core.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\Microsoft.Win32.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\mscorlib.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\netstandard.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.AppContext.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Collections.Concurrent.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Collections.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Collections.NonGeneric.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Collections.Specialized.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ComponentModel.Composition.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ComponentModel.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ComponentModel.EventBasedAsync.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ComponentModel.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ComponentModel.TypeConverter.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Console.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Core.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Data.Common.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Data.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.Contracts.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.Debug.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.FileVersionInfo.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.Process.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.StackTrace.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.TextWriterTraceListener.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.Tools.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.TraceSource.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Diagnostics.Tracing.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Drawing.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Drawing.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Dynamic.Runtime.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Globalization.Calendars.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Globalization.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Globalization.Extensions.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.Compression.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.Compression.FileSystem.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.Compression.ZipFile.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.FileSystem.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.FileSystem.DriveInfo.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.FileSystem.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.FileSystem.Watcher.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.IsolatedStorage.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.MemoryMappedFiles.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.Pipes.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.IO.UnmanagedMemoryStream.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Linq.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Linq.Expressions.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Linq.Parallel.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Linq.Queryable.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.Http.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.NameResolution.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.NetworkInformation.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.Ping.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.Requests.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.Security.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.Sockets.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.WebHeaderCollection.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.WebSockets.Client.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Net.WebSockets.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Numerics.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ObjectModel.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Reflection.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Reflection.Extensions.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Reflection.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Resources.Reader.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Resources.ResourceManager.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Resources.Writer.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.CompilerServices.VisualC.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Extensions.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Handles.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.InteropServices.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.InteropServices.RuntimeInformation.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Numerics.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Serialization.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Serialization.Formatters.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Serialization.Json.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Serialization.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Runtime.Serialization.Xml.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.Claims.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.Cryptography.Algorithms.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.Cryptography.Csp.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.Cryptography.Encoding.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.Cryptography.Primitives.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.Cryptography.X509Certificates.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.Principal.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Security.SecureString.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ServiceModel.Web.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Text.Encoding.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Text.Encoding.Extensions.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Text.RegularExpressions.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Threading.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Threading.Overlapped.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Threading.Tasks.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Threading.Tasks.Parallel.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Threading.Thread.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Threading.ThreadPool.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Threading.Timer.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Transactions.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.ValueTuple.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Web.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Windows.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.Linq.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.ReaderWriter.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.Serialization.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.XDocument.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.XmlDocument.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.XmlSerializer.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.XPath.dll
 -r:C:\Users\dsyme\.nuget\packages\netstandard.library\2.0.0-preview2-25401-01\build\netstandard2.0\\ref\System.Xml.XPath.XDocument.dll
 --target:library
 --warn:3
 --warnaserror:76
 --fullpaths
 --flaterrors
 --highentropyva-
 --targetprofile:netcore
 --simpleresolution
 --nocopyfsharpcore
 FSharpOriginalNBody.fs
 C:\Users\dsyme\AppData\Local\Temp\.NETStandard,Version=v2.0.AssemblyAttributes.fs

[enricosada]

that there is no FSharp.Core.dll in
would have thought it would exist since FSharp.Core.dll is, I assume, added as a default dependency package of both the F# tester app and the F# library, as mentioned here

the FSharp.Core dll is never copied in output dir for build (works like that for all assemblies), that's why we pass --nocopyfsharpcore to fsc. List of assemblies is in the .deps.json file

the FSharp.Core is copied (again, with all deps) on dotnet publish

about this error

@dsyme i tried locally too, same repo. and i cannot repro the error.

[dsyme]

@enricosada @cartermp Please review the linked PR

@enricosada I'm surprised the error doesn't repro - it sure did for me. I reduced the 5000000 to 5000 to make it show quickly. Note you have to switch the DotNetCore2preview2Bug branch of the repo

[dsyme]

@enricosada Since this is high priority, to get correct codegen for .NET SDK 2.0 preview 2, could you possibly try the linked PR? I've got to go out now and haven't been able to try it manually as yet - I need to find the right way to use the freshly built bits

[enricosada]

@dsyme i'll try tonight. maybe i can repro using the same fsc command, dunno.

my dotnet version is 2.0.0-preview2-006391, i'll try also with latest from dotnet/cli

btw i was in master branch, thx for hint.
but i cannot repro anyway, output is ok.

Improved C# Mandelbrot faster than original. Expected function results to be the same ([|0uy; 63uy; 1uy; 0uy; 7uy; 191uy; ..

[enricosada]

I cannot repro.
i tried multiple cli versions, with and without dotnet core feed, in debug and release.
I'll send a PR there with a test

[enricosada]

Ok, if i cannot repro locally, it should in CI.
Opening dotnet/cli#6914 to add an F# end 2 test test (app with lib). @dsyme i hope we can use this test to confirm this is fixed.