std.traits.Fields(T), FieldNameTuple(T) - order guaranteed?

[Meta via Digitalmars-d]

On Wednesday, 27 July 2016 at 13:09:07 UTC, Liam McSherry wrote:
> Since it isn't mentioned in the documentation, do 
> `std.traits.Fields(T)` and `std.traits.FieldNameTuple(T)` 
> return the fields and field names in a deterministic order?
>
> Further, will they return the fields/field names in the same 
> order? That is, will `fields[0]` be the type of 
> `field_names[0]`?

I think you should be safe here as Fields is basically a wrapper 
around T.tupleof, which should always return fields in the same 
order. It's not guaranteed anywhere, but it's highly unlikely to 
change.

Since FieldNameTuple is also implemented using T.tupleof, you 
*can* expect Fields!T[0] to be the type of FieldNameTuple!T[0]. 
Again, however, this is an implementation detail that is unlikely 
to change but is not guaranteed.