var a: Float = 10

let _: @autodiff (Float) -> Float = { x in
  a = x
  return x + x
}

// closure #​1 in
sil private @$s13test_activityS2fcfU_ : $@convention(thin) (Float) -> Float {
// %0                                             // users: %4, %8, %8, %2
bb0(%0 : $Float):
  %1 = global_addr @$s13test_activity1aSfvp : $*Float // user: %3
  debug_value %0 : $Float, let, name "x", argno 1 // id: %2
  %3 = begin_access [modify] [dynamic] %1 : $*Float // users: %4, %5
  store %0 to %3 : $*Float                        // id: %4
  end_access %3 : $*Float                         // id: %5
  %6 = metatype $@thin Float.Type                 // user: %8
  // function_ref static Float.+ infix(_:_:)
  %7 = function_ref @$sSf1poiyS2f_SftFZ : $@convention(method) (Float, Float, @thin Float.Type) -> Float // user: %8
  %8 = apply %7(%0, %0, %6) : $@convention(method) (Float, Float, @thin Float.Type) -> Float // user: %9
  return %8 : $Float                              // id: %9
} // end sil function '$s13test_activityS2fcfU_'

[AD] Activity info for $s13test_activityS2fcfU_ at (source=0 parameters=(0))
[ACTIVE] %0 = argument of bb0 : $Float                     // users: %4, %8, %8, %2
[USEFUL]   %1 = global_addr @$s13test_activity1aSfvp : $*Float // user: %3
[ACTIVE]   %3 = begin_access [modify] [dynamic] %1 : $*Float // users: %4, %5
[NONE]   %6 = metatype $@thin Float.Type                 // user: %8
[NONE]   // function_ref static Float.+ infix(_:_:)
  %7 = function_ref @$sSf1poiyS2f_SftFZ : $@convention(method) (Float, Float, @thin Float.Type) -> Float // user: %8
[ACTIVE]   %8 = apply %7(%0, %0, %6) : $@convention(method) (Float, Float, @thin Float.Type) -> Float // user: %9
[AD] Cloning original @$s13test_activityS2fcfU_ to primal @AD__$s13test_activityS2fcfU___primal_src_0_wrt_0
[AD] Found static checkpoint   %3 = begin_access [modify] [dynamic] %1 : $*Float