F# compiler doesn't emit default parameter value for some types

Consider these C# and VB.NET declarations that have default parameter values:
```csharp
public class C1
{
public static void M(decimal x = 4) => Console.Write(x);
}
```
```vbnet
Public Class C2
Public Shared Sub M(Optional d As Date = #2018/01/01#)
Console.WriteLine(d)
End Sub
End Class
```

F# compiler allows using these methods without specifying values for the optional parameters:
```fsharp
C1.M()
C2.M()
```

The problem is it doesn't emit the parameter default values inside the calls, and emits type default values instead.
However, it works as expected when other allowed types are used, like `int` or `string`.
Since F# compiler allows skipping arguments for such parameters it seems that emitting the type default value, especially only for some types while working properly for others, might be a bug.