F# implemented abstract static member causes Bad image format invoked through reflection

Repro steps

In order to reproduce the issue I create an implementation of IParsable from F#, then invoke it through reflection

open System
open System.ComponentModel

// from https://madskristensen.net/post/A-shorter-and-URL-friendly-GUID
let toStr (x : Guid) = 
    let enc = Convert.ToBase64String(x.ToByteArray())
    let enc = enc.Replace("/", "_").Replace("+", "-")
    enc.Substring(0, 22)

let fromStr (encoded : string) = 
    let encoded = encoded.Replace("_", "/").Replace("-", "+")
    let buffer = Convert.FromBase64String(encoded + "==")
    if buffer.Length = 16 then Some(Guid buffer)
    else None

let tryParseId (prefix : string) (str : string) = 
    if str.StartsWith(prefix) then fromStr (str.Substring prefix.Length)
    else None

let parseId prefix str = 
    let maybeParsed = tryParseId prefix str
    match maybeParsed with
    | Some g -> g
    | None -> raise (FormatException str)

type CustomerId = 
    { Value : Guid }
    static member Default : CustomerId = { Value=Guid.Empty }
    static member Parse(str : string) : CustomerId = { Value = parseId "c-" str }
    override this.ToString() = sprintf "c-%s" (toStr this.Value)
    interface IParsable<CustomerId> with
        static member Parse(s:string, f:IFormatProvider) = CustomerId.Parse(s)
        static member TryParse(s:string, f:IFormatProvider, result:byref<CustomerId>) =
            try
                result <- CustomerId.Parse(s)
                true
            with _ ->
                result <- Unchecked.defaultof<_>
                false
typeof<CustomerId>.GetInterface("IParsable`1").GetMethod("Parse").Invoke(null, [| "c-ReJ_cYj8l0WmonC0k0hQvw"; null |]);;
(**
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> System.BadImageFormatException: Bad IL format.
   at InvokeStub_IParsable`1.Parse(Object, Object, IntPtr*)
   at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr)
   --- End of inner exception stack trace ---
   at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at <StartupCode$FSI_0030>.$FSI_0030.main@() in /Users/mathieu/src/cs/Saithe/stdin:line 158
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
   at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr)
Stopped due to error
*)

Expected behavior

If you implement the same logic but with an instance interface then you get the expected behaviour:

type IParsableInst<'T> = interface
    abstract member Parse : string -> 'T
    abstract member TryParse : string*byref<'T> -> bool
end

type CustomerId2 = 
    { Value2 : Guid }
    static member Default : CustomerId2 = { Value2=Guid.Empty }
    static member Parse(str : string) : CustomerId2 = { Value2 = parseId "c-" str }
    override this.ToString() = sprintf "c-%s" (toStr this.Value2)
    interface IParsableInst<CustomerId2> with
        member this.Parse(s:string) = CustomerId2.Parse(s)
        member this.TryParse(s:string, result:byref<CustomerId2>) =
            try
                result <- CustomerId2.Parse(s)
                true
            with _ ->
                result <- Unchecked.defaultof<_>
                false

typeof<CustomerId2>.GetInterface("IParsableInst`1").GetMethod("Parse").Invoke(CustomerId2.Default, [| "c-ReJ_cYj8l0WmonC0k0hQvw" |]);;
// val it: obj = { Value2 = 717fe245-fc88-4597-a6a2-70b4934850bf }

Actual behavior

Throws System.BadImageFormatException

Known workarounds

It’s a new feature in .net.

Related information

• Operating system (Windows Appveyor Visual Studio 2022 image, Mac OS X, GitHub Ubuntu latest (at the time of writing 2022-11) )
• .NET Runtime kind (.NET 7.0.100)

[wallymathieu]

Unless they have the same issue?

[wallymathieu]

Thanks! I’ll report it to the runtime repo!