Build fails with Error FS2014, error: MethodDef not found when using static abstract stuff

[En3Tho]

Stumbled upon this recently when trying to make C#-like task builder which only requires the user to define awaiter, builder and task types

Repro steps
Extract the archive, try to build the solution
ClassLibrary1.zip

Tried it with net7 and net8 without any luck

[vzarytovskii]

To add: it affects only reference assembly generation, turning refassemblies off should be a feasible workaround until it's fixed.

[En3Tho]

@vzarytovskii Maybe I did something wrong, but turning off reference assembly generation did not help but the error message changed slightly

[En3Tho]

It seems like is set to false by default
With explicitly set false

FSC : error FS2014: Проблема при записи двоичного файла "G:\source\repos\En3Tho\FSharpExtensions\FSharpExtensions\StaticAbstractTest\obj\Debug\net7.0\StaticAbstractTest.dll"
: Error in pass3 for type StaticAbstractTest.MyValueTaskMethodBuilder`1, error: Error in GetMethodRefAsMethodDefIdx
for mref = ("En3Tho.FSharp.ComputationExpressions.Utilities.IAsyncMethodBuilderBase<StaticAbstractTest.MyValueTas kMethodBuilder<'a>>.Create", "StaticAbstractTest.MyValueTaskMethodBuilder`1"),
error: MethodDefNotFound [G:\source\repos\En3Tho\FSharpExtensions\FSharpExtensions\StaticAbstractTest\StaticAbstractTest.fsproj]

With explicitly set true

FSC : error FS2014: Проблема при записи двоичного файла "obj\Debug\net7.0\refint\En3Tho.FSharp.ComputationExpressions.dll"
: Error in pass3 for type En3Tho.FSharp.ComputationExpressions.Tasks.MyValueTaskMethodBuilder`1, error: Error in GetMethodRefAsMethodDefIdx
for mref = "En3Tho.FSharp.ComputationExpressions.Utilities.IAsyncMethodBuilderBase<En3Tho.FSharp.ComputationExpressions.Tasks.MyValueTaskMethodBuilder<'a>>.Create", "En3Tho.FSharp.ComputationExpressions.Tasks.MyValueTaskMethodBuilder`1"),
error: MethodDefNotFound [G:\source\repos\En3Tho\FSharpExtensions\FSharpExtensions\En3Tho.FSharp.ComputationExpressions\En3Tho.FSharp.ComputationExpressions.fsproj]

Note that when producing reference assembly, the only difference is "refinit" is in the path. Also, file name is not the full path but relative for some reason.

I'm not sure this is a regression because it's reproduceable both on .Net 7 and .Net 8.

P.S. It seems like I did post errors above from my main solution but repro project behaves the same. Sorry for confusion.

[En3Tho]

@vzarytovskii I can confirm reference assemblies have nothing to do with this again. I've managed to come up with a minimal repro. This is clearly a compiler bug.

a minimal repro:

type IHasStaticAbstractBase<'a> =
    static abstract Boom: unit -> 'a

type IHasStaticAbstractChild<'a> =
    inherit IHasStaticAbstractBase<'a>

type CompilerGoesBoom<'a>() =
    interface IHasStaticAbstractChild<'a> with // this goes boom because inheritance is involved
        static member Boom() = Unchecked.defaultof<'a>

type CompilerDoesNotGoBoom<'a>() =
    interface IHasStaticAbstractBase<'a> with // this does not go boom, direct base interface
        static member Boom() = Unchecked.defaultof<'a>

My best guess is that it is trying to find Boom member on IHasStaticAbstractChild<'a> and is unable to do so. It has to walk up the inheritance chain just like with non static members (or maybe IHasStaticAbstractChild<'a> should have it, I don't know).

[gusty]

Can we change the impact?
I don't think this is low impact at all, if you start using static abstracts chances are that at some point you'll find this bug.
It doesn't look like a corner case.

[vzarytovskii]

Can we change the impact?

I don't think this is low impact at all, if you start using static abstracts chances are that at some point you'll find this bug.

It doesn't look like a corner case.

Impact is internal for our own usage only.

It mostly means it doesn't impact any existing code.