Please provide a succinct description of the issue.

Repro steps

Enable nullable.

type T () =
    let mutable v : T | null = null
    member val P : T | null = null with get, set
    member this.M() =
        v <- null
        this.P <- null

let mutable v can assign null as expected.
But member val P cannot assign null, it causes FS3261.

Expected behavior

compile it successfully.

Actual behavior

It causes FS3261 warning.

Program.fs(6,19): warning FS3261: Nullness warning: The types 'T' and 'T | null' do not have compatible nullability.

Known workarounds

Use Uncheked.defaultof<T | null>.

Related information

Provide any related information (optional):

• Windows 11
• .NET 9 RC1
• Visual Studio Professional Preview 17.12.0 Preview 2.0