F# Statically Resolved Type Parameters and call syntax

// this works as expected
type Example() =
  member __.F(i) = printfn "%d" i

let inline f (x : ^a) =
  (^a : (member F : int -> unit) (x, 1))
  (^a : (member F : int -> unit) (x, 2))

f (Example())

// this doesn't work
let inline f (x : ^a when ^a : (member F : int -> unit)) =
  // the compiler knows that there must be member F and its signature
  // so the following should be possible
  x.F(1)
  x.F(2)