Mixing named arguments + callback style and getter should not compile

[MangelMaxime]

I think the code below should not compile.

Repro steps

Provide the steps required to reproduce the problem:

type LabeledProperty = 

    abstract member alert: title:string * message:string option -> unit with get,set

Looking at the C# output it gives the following result which looks incomplete.

[CompilationMapping(SourceConstructFlags.Module)]
public static class @_
{
    [Serializable]
    [CompilationMapping(SourceConstructFlags.ObjectType)]
    public interface LabeledProperty
    {
        override Unit alert { get; set; }
    }
}

Expected behavior

F# compiler should fails the compilation ?

Provide any related information (optional):

• Operating system: OSX
• .NET Runtime kind (.NET Core, .NET Framework, Mono): .NET Core 8.0.401
• Editing Tools (e.g. Visual Studio Version, Visual Studio)

[T-Gro]

Changed name, there is no "DU" involved in this case.

The codegen is definitely wrong.

Out of the 4 options here, only alert3 and alert4 are correct, the others are a bug/missing error:
https://sharplab.io/#v2:DYLgZgzgPg9gDgUwHYAIDKBPCAXBBbAWAChjsNEUBZDAMQFckBjFAXhRwCcBLJAcxQBU7bNz4p42LjFQBaAHwoGXbMVLkEKADIBDAEYJgCACYAFDvAQcyrFKqIoHKPZ22NsKPPn0cnhqyBRJbEMQTh5+IU8ICG1eBFCRcPE4SWkUeUUkZRQAd2UACxQ47AAaCAQVe0dnEVd3TzxvX0tsACYAsLEhTv4JKVkFJXc87ELisoriRyddFzcPL0tmqwBmAIAKHsFhUV6U/vTBrOwASlyCooqJyumajjqFxqXtP2wAFgDqeiZz0cvS8rYIA===

type MyFunc = string * string option -> unit

type LabeledProperty = 

    abstract member alert: title:string * message:string option -> unit with get,set
    abstract member alert2: string * string option -> unit with get,set
    abstract member alert3: (string * string option -> unit) with get,set
    abstract member alert4: MyFunc with get,set

[edgarfgp]

It seems that it you use Item as the member name, aka Indexer properties(get, set) it adds the missing codegen. :)

type LabeledProperty =

    abstract member Item: title:string * message:string option -> unit with get,set

[CompilationMapping(SourceConstructFlags.Module)]
public static class @_
{
    [Serializable]
    [CompilationMapping(SourceConstructFlags.ObjectType)]
    public interface LabeledProperty
    {
        override Unit this[string title, FSharpOption<string> message] { get; set; }
    }
}

See sharplab