Thank you, this looks interesting and I'll have a closer look later. In the meantime:

    template <typename Derivate>
    friend class NodeTraits;

is unfortunately a something that's a bit plagued by compiler errors, some compilers require this, while others insist that it's not present. Please see,
https://github.com/BlueBrain/HighFive/blob/master/include/highfive/H5Selection.hpp#L61-L64

for example. If CI complains, please adjust accordingly.

Thank you for your quick reply.
I thought the protection was legacy since this type of declaration is unprotected elsewhere like here: https://github.com/BlueBrain/HighFive/blob/master/include/highfive/H5DataSet.hpp#L112-L113
CI does not seems to complain about that but i can correct if needed.
Moreover, I have some trouble to understand why the CI is complaining about a memory leak.

So the leak is not your responsibility (I think it was only not tested), and this is here: https://github.com/BlueBrain/HighFive/blob/master/include/highfive/H5DataType.hpp#L242
We have to free that.

Codecov Report

Merging #796 (e901735) into master (d2b1173) will increase coverage by 0.04%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master     #796      +/-   ##
==========================================
+ Coverage   84.21%   84.25%   +0.04%     
==========================================
  Files          68       68              
  Lines        4776     4795      +19     
==========================================
+ Hits         4022     4040      +18     
- Misses        754      755       +1