Tooling implies that _ in member body refers to the instance identifier when it is actually a wildcard pattern

[brianrourkeboll]

When an instance member uses a single underscore _ as its "this" or instance identifier (fsharp/fslang-suggestions#333), the F# tooling implies that any _ pattern used in the member body refers to the instance, even though it does not.

Repro steps

type T () =
    member _.M () =
        fun _ -> ()
        //  ↑ Shows unexpected val _:T on hover.

    member _.N () =
        let _ = () in ()
        //  ↑ Shows unexpected val _:T on hover.

    member this.O () =
        let _ = () in ()
        //  ↑ Shows nothing on hover, as expected.

Expected behavior

Any _ patterns in a member body whose instance identifier is also _ should nonetheless be treated by the tooling like wildcard patterns are in general, and nothing should be shown on hover.

expected.mp4

Actual behavior

Any _ patterns in a member body whose instance identifier is also _ are treated by the tooling as though they refer to the instance identifier.

unexpected.mp4

Known workarounds

N/A.

Related information

Applies to VS and VS Code, .NET 8 and 9 (and probably earlier?).