error FS0193: ...ConstraintSolver+LocallyAbortOperationThatFailsToResolveOverload

[ptrelford]

While trying to build a project on VS2017 the compiler gives the following error message:

error FS0193: internal error: Exception of type 'Microsoft.FSharp.Compiler.ConstraintSolver+LocallyAbortOperationThatFailsToResolveOverload' was thrown.

Repro steps

1. Create an F# Console project
2. Add the latest preview release of Freya (4.0.0-alpha-170404) from Nuget
3. Add the following code to Program.fs

open Freya.Core
open Freya.Machines.Http

let throwError = 
    freyaMachine { 
        handleOk ( fun (acceptable:Acceptable) -> 
            freya { 
                return Represent.text "Something"
            })
    }

Solution: MyFreyaCompilerError.zip

4. Attempt to build the project.

Expected behavior

The code should compile as it did in VS2015.

Actual behavior

The code gives an internal compiler error.

Known workarounds

Continue to use VS2015 instead of VS2017.

Related information

• Windows 10 Pro
• .NET Runtime 4.6.1
• Microsoft Visual Studio Community 2017 (Version 15.1 (26403.7) Release)
• Visual F# 4.1 00369-60000-00001-AA410

[forki]

can you please upload a zip with the full code?

[ptrelford]

That is all the code, please see attached
MyFreyaCompilerError.zip

[forki]

nuget restore failed for me. but after "paket convert-from-nuget" I can repro.

Here is the full code with packages restored: freya.zip

[dsyme]

Can someone get a full stack for where that exception is first raised?

[forki]

There is only one place in the code base where it's created. Am 19.07.2017 22:35 schrieb "Don Syme" <notifications@github.com>:

…

Can someone get a full stack for where that exception is first raised? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3343 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AADgNM4tVJUGRmfgeaosrSwtmMOE2vqIks5sPmh0gaJpZM4OaBtb> .

[dsyme]

@forki Yes, but there are multiple places where the constraint solver is called. All paths to this should be protected by catch handlers, we must be missing one

[forki]

Yeah I try to debug it. But had no luck because of other vs2017 issues like keyboard freeze and crashes. Then gave up.

[dsyme]

@forki Looking at the code I can see that it's possible for it to escape. The guilty PR is 0c37abe

[forki]

/cc @gusty

[forki]

the pattern match on LocallyAbortOperationThatFailsToResolveOverload probably needs to be added here as well 0c37abe#diff-641da7c52ffc888699888ebd03559cb5R2505 right?

[forki]