Pattern discard allowed for union case that takes no data

Match discards aren’t type checked against case

    type X = X 

    let test() =
        match X with
        | X _ -> () // No error X doesn't have arguments

[dsyme]

Things have changed a bit since 2016, and we now are more inclined to emit new informationals and warnings, protected by a /langversion switch.

So I’d definitely be ok with emitting at least an informational, and possibly a warning for this case.

[vzarytovskii]

I agree that warning + language switch is better in making this more visible. Info-warnings are use very sparsely, typically only when deprecating language features…

Agree, I think it should be a warning behind language version. It should also be easy to add a quick fix to VS (and other IDEs) which will be removing unnecessary discards.