Function drop_flag_effects_for_function_entry 

pub fn drop_flag_effects_for_function_entry<'tcx, F>(
    body: &Body<'tcx>,
    move_data: &MoveData<'tcx>,
    callback: F,
)
where
    F: FnMut(MovePathIndex, DropFlagState),

Calls callback for each child move path of the function’s arguments. Note the move paths’ DropFlagState argument to the callback will always be DropFlagState::Present.