fsharp FS2014 when using tupled args

Repro

module Thing
let error =
    let f _ _ _ (stateA, resultA) (stateB, resultB) _ =
        if stateA && stateB then resultA else resultB
    f () () () (true, ()) (true, ()) ()

Zip file with the repro case: FS2014.zip

Expected behavior

Compiles without problem.

Actual behavior

Severity	Code	Description	Project	File	Line	Suppression State
Error	FS2014	A problem occurred writing the binary 'C:\Users\Admin\source\repos\FS2014\FS2014\obj\Debug\netcoreapp2.1\FS2014.dll': Error in pass2 for type Thing, error: Error in pass2 for type f@3TTTTTD, error: duplicate entry 'tupledArg' in field table	FS2014	C:\Users\Admin\source\repos\FS2014\FS2014\FSC	1	Active

Known workarounds

Modify f, e.g. removing arguments, replacing function body

Related information

Microsoft Visual Studio Community 2017 Version 15.9.9 VisualStudio.15.Release/15.9.9+28307.518 Microsoft .NET Framework Version 4.7.03056

Installed Version: Community

Visual C++ 2017 00369-60000-00001-AA735 Microsoft Visual C++ 2017

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Mar 25 '19 12:03 Happypig375

Can confirm, happens when compiling as Debug in VS. Release seems to work though.

Mar 25 '19 18:03 TIHan

I believe have a similar error

FSC : error FS2014: A problem occurred writing the binary 'C:\Users\slavinr\Source\Repos\errorFS2014\ConsoleApp\obj\Debug\netcoreapp3.1\ConsoleApp.dll': Error in pass3 for type Program, error: Error in pass3 for type MyClass, error: Error in GetMethodRefAsMethodDefIdx for mref = ("Example-IMessageReader`1-TryParseMessage", "MyClass"), error: Exception of type 'FSharp.Compiler.AbstractIL.ILBinaryWriter+MethodDefNotFound' was thrown. [C:\Users\slavinr\Source\Repos\errorFS2014\ConsoleApp\ConsoleApp.fsproj]

when trying to compiler the following code

type BaseMessage = 
  struct
    val Payload : ReadOnlySequence<byte>
    new (payload: ReadOnlySequence<byte>) = { Payload = payload }
  end

type MyClass() =

  interface IMessageReader<BaseMessage> with
      member this.TryParseMessage(input: inref<ReadOnlySequence<byte>>, consumed: byref<SequencePosition>, examined: byref<SequencePosition>, message: byref<BaseMessage>): bool = 
          failwith "Not Implemented"

The interface is defined in a seperate C# project

Repro here: https://github.com/auslavs/errorFS2014

Jan 07 '20 11:01 auslavs

@auslavs which VS version are you using? Does this also reproduce in release?

Jan 07 '20 15:01 cartermp

@cartermp yep, same thing for release.

VS Details below, I have repro'd in VS, VsCode and using dotnet build.

Microsoft Visual Studio Professional 2019 Version 16.4.2 VisualStudio.16.Release/16.4.2+29613.14 Microsoft .NET Framework Version 4.8.03761

Installed Version: Professional

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Azure App Service Tools v3.0.0 16.4.457.38025 Azure App Service Tools v3.0.0

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Azure Data Lake Tools for Visual Studio 2.4.1000.0 Microsoft Azure Data Lake Tools for Visual Studio

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C# Tools 3.4.1-beta4-19610-02+c4e5d138903b899477649a17f197abd2bcb22f9e C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

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Microsoft Azure HDInsight Azure Node 2.4.1000.0 HDInsight Node under Azure Node

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Microsoft Visual Studio Tools for Containers 1.1 Develop, run, validate your ASP.NET Core applications in the target environment. F5 your application directly into a container with debugging, or CTRL + F5 to edit & refresh your app without having to rebuild the container.

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Visual F# Tools 10.4 for F# 4.6 16.4.0-beta.19556.5+e7597deb7042710a7142bdccabd6f92b0840d354 Microsoft Visual F# Tools 10.4 for F# 4.6

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Jan 07 '20 20:01 auslavs

It appears as though my issue was with the inref. The C# Interface uses a in modifier on the first parameter, removing this requirement also removes the compiler error.

Jan 18 '20 09:01 auslavs

But that would suggest that implementing an interface with inref is not possible. Maybe that's by design, but if so, it would be nice to have the error at an earlier stage than when writing the binary.

Jan 18 '20 13:01 abelbraaksma

@abelbraaksma I can't seem to find any info on whether or not it is by design. Th byrefs seem to work fine though.

I share you sentiment that it would be good to know about this earlier if it was by design

Jan 20 '20 10:01 auslavs

@auslavs This is a compiler bug and should compile and run successfully. I will spend time on resolving it this week.

Jan 20 '20 11:01 TIHan

So, @auslavs , the error you have is similar to the one reported here, but the cause is very different. I have a fix for your issue: https://github.com/dotnet/fsharp/pull/8287

Regarding this issue, I will look into; it's been almost a year.

Jan 20 '20 12:01 TIHan

@TIHan Thank you very much!

Jan 22 '20 01:01 auslavs

I know how it is caused, The following user code can avoid this bug:

module Thing =

   let error() =
      let f _ _ _ ((stateA, resultA)) ((stateB, resultB)) () =
         if stateA && stateB then 
            resultA 
         else 
            resultB
      f () () () (true, ()) (true, ()) ()

I think it puts all arguments in a tuple when it starts to compile that code. When there are more than 7 elements, the following arguments are placed in the sub-tuple of rest, so two tupledArg0 are generated.

Dec 08 '21 14:12 RealmPlume

Got hit by the same problem yesterday (2024!) ... is this ever going to get fixed?

My solution was to remove the type of an argument(wth?!?!):

module Smtp =
    module SendEmail =
        let doNothing
            (log: Log)
            (senderNameAndEmailAddress: string * string)
            (replyToNameAndEmailAddress: (string * string) option)
            recipientNameAndEmailAddress
            // NOTE: Below does NOT work, if compiled in Release mode error is thrown: FSC : error FS2014: A problem occurred writing the binary 'obj/Release/net8.0/refint/NotificationService.CommandHandling.IntegrationTests.dll': Error in pass2 for type NotificationService.CommandHandling.IntegrationTests.DependencyInjection, error: Error in pass2 for type Api, error: Error in pass2 for type sendNotificationMockedEmail@41D, error: duplicate entry 'tupledArg' in field table [/home/deyan/gitw/Main/code/NotificationService/tests/NotificationService.CommandHandling.IntegrationTests/NotificationService.CommandHandling.IntegrationTests.fsproj]
            // See also https://github.com/dotnet/fsharp/issues/6379
            // (recipientNameAndEmailAddress: string * string)
            (subject: string)
            (body: string)
            : AsyncResult<unit, string>
            =
            ...

Dec 18 '24 06:12 deyanp

This happens here:

https://github.com/dotnet/fsharp/blob/ee559975b208d5eb64cc9c3c832a29de1bf5f131/src/Compiler/TypedTree/TypedTreeOps.fs#L8344-L8358

https://github.com/dotnet/fsharp/blob/ee559975b208d5eb64cc9c3c832a29de1bf5f131/src/Compiler/TypedTree/TypedTreeOps.fs#L8360-L8405

At first it would seem like we could trivially make the compiler-generated name unique (with an index suffix or whatever), but I wonder if that could affect places like this:

https://github.com/dotnet/fsharp/blob/ee559975b208d5eb64cc9c3c832a29de1bf5f131/src/FSharp.Core/Query.fs#L1027

But untupledToRefTupled seems iffy in other ways, too. Among other things, it also allows declaring multiple parameters with the same name (really, binding the same named patterns multiple times), for example:

SharpLab

//let ((x, y), (x, y)) = ((1, 2), (3, 4)) // Should not compile, does not compile.
//let f (x, y) (x, y) = x + y // Should not compile, does not compile.
let f' ((x, y)) ((x, y)) = x + y // Should not compile, compiles.
let f'' ((x, y), (x, y)) = x + y // Should not compile, compiles.

Feb 07 '25 22:02 brianrourkeboll

@brianrourkeboll :

Since the code fails to compile as of now, the risk of binary breaking changes for existing code is small and we could take it - assuming the new generated name would only appear for subsequent tupleArg items.

The places would have to changed and older FSharp.Core would not support them in queries, but it is better then leaving the bug as is (= fails to write IL binary).

Feb 11 '25 13:02 T-Gro