byref analysis not working with type abbreviations #7934

open System

type Bytes = ReadOnlySpan<byte>

type Foo() =
           
    //member this.foo1 (data: ReadOnlySpan<byte>) =
    //    let x = 
    //        if false then
    //            failwith "" // Error FS0412: A type instantiation involves a byref type. This is not permitted by the rules of Common IL
            
    //        else
    //            data
    //    x

    //member this.foo2 (data: ReadOnlySpan<byte>) =
    //    let x = 
    //        if false then
    //            failwithf "" // Error FS0412: A type instantiation involves a byref type. This is not permitted by the rules of Common IL
    //        else
    //            data
    //    x

    member this.foo3 (data: Bytes) =
        let x = 
            if false then // true or false doesn't matter
                failwith ""
            else
                data
        x

    member this.foo4 (data: Bytes) =
        let x = 
            if false then
                failwithf ""
            else
                data
        x

[<EntryPoint>]
let main argv =
    let span = ReadOnlySpan<_>(Array.empty)
    let result = Foo().foo3(span)
    let result = Foo().foo4(span)
    0