message: hdf5-derive: use syn::Index for tuple structs
diff: @@ -9,8 +9,8 @@ use std::str::FromStr;
  use proc_macro2::{Ident, Span, TokenStream};
  use quote::{quote, ToTokens};
  use syn::{
  - parse_macro_input, AttrStyle, Attribute, Data, DeriveInput, Expr, Fields, Meta, NestedMeta,
  - Type, TypeGenerics, TypePath,
  + parse_macro_input, AttrStyle, Attribute, Data, DeriveInput, Expr, Fields, Index,
  + Meta, NestedMeta, Type, TypeGenerics, TypePath,
  };
  #[proc_macro_derive(H5Type)]
  @@ -146,11 +146,12 @@ fn impl_trait(
  impl_compound(ty, ty_generics, &fields, &names, &types)
  }
  Fields::Unnamed(ref fields) => {
  - let (index, fields): (Vec<usize>, Vec<_>) = fields
  + let (index, fields): (Vec<Index>, Vec<_>) = fields
  .unnamed
  .iter()
  .enumerate()
  .filter(|&(_, f)| !is_phantom_data(&f.ty))
  + .map(|(i, f)| (Index::from(i), f))
  .unzip();
  if fields.is_empty() {
  panic!("Cannot derive H5Type for empty tuple structs");
  