Visual Studio incorrectly suggests "Open declaration can be removed"

[nikonthethird]

Visual Studio 2017 with the latest Updates shows "Open declaration can be removed" suggestion even when a type from the opened module is used.

Repro steps

Put the following code into an .fsx file and open it in Visual Studio. The line open DeclaresA will be grayed out.

module DeclaresA =
    type A = class end

module UsesA =
    open DeclaresA

    let a = Unchecked.defaultof<A>

Expected behavior

It should not be grayed out.

Actual behavior

It is grayed out, the tooling thinks nothing of the opened module is used.

Known workarounds

Since it is just a suggestion, simply ignoring it works.

Related information

• Windows 10
• .NET 4.5
• Visual Studio 2017 with all Updates installed

[nikonthethird]

Something's also not quite right when using type aliases:

module DeclaresA =
    // type A () = class end // (1)
    type A = System.Int32 // (2)

open DeclaresA

let a = A ()

If the type A marked with (1) is uncommented, everything is fine.
If the type alias A marked with (2) is uncommented as shown, Visual Studio will once again suggest to remove the open statement.

[nikonthethird]

One more observation: The CompilationRepresentationAttribute has an effect:

Create a new F# project in Visual Studio 2017 and create two Files: ContainerOne.fs and ContainerTwo.fs.

ContainerOne.fs:

[<CompilationRepresentation (CompilationRepresentationFlags.ModuleSuffix)>] // (1)
module Example.ContainerOne

type Test = {
    Value : System.String
}

ContainerTwo.fs:

module Example.ContainerTwo

open Example.ContainerOne

let test = {
    Value = "Hello"
}

You will see that open Example.ContainerOne is once again gray:

But, if you comment out the line marked with (1) in ContainerOne.fs, it suddenly is fine.

I think what's throwing off the tooling here is that the Test record has the full name Example.ContainerOneModule.Test (as seen when hovering over the record type name), but the open declaration refers only to Example.ContainerOne, and those are different.

[cartermp]

This appears fixed on all counts with 15.3.5.