message: Stop using mem::transmute(0usize) for get_val invocation
diff: @@ -131,13 +131,12 @@ macro_rules! implement_vertex {
  offset
  },
  {
  - fn attr_type_of_val<T: $crate::vertex::Attribute>(_: &T)
  + fn attr_type_of_val<T: $crate::vertex::Attribute>(_: Option<&T>)
  -> $crate::vertex::AttributeType
  {
  <T as $crate::vertex::Attribute>::get_type()
  }
  - let dummy: &$struct_name = unsafe { ::std::mem::transmute(0usize) };
  - attr_type_of_val(&dummy.$field_name)
  + attr_type_of_val(None::<&$struct_name>.map(|v| v.$field_name))
  },
  false
  )
  @@ -166,13 +165,12 @@ macro_rules! implement_vertex {
  dummy_field
  },
  {
  - fn attr_type_of_val<T: $crate::vertex::Attribute>(_: &T)
  + fn attr_type_of_val<T: $crate::vertex::Attribute>(_: Option<&T>)
  -> $crate::vertex::AttributeType
  {
  <T as $crate::vertex::Attribute>::get_type()
  }
  - let dummy: &$struct_name = unsafe { ::std::mem::transmute(0usize) };
  - attr_type_of_val(&dummy.$field_name)
  + None::<&$struct_name>.map(|v| v.$field_name)
  },
  {
  $should_normalize
  