Use [repr(transparent)] instead of [repr(C)]

[TimDiekmann]

Since [repr(transparent)] is now stabilized you may consider to use it instead of [repr(C)] for the handles (here and here).

I'd do a PR if you want. This could also be enabled with a feature.

[MaikKlein]

We will switch to it when it is on stable.

[zakarumych]

It should be stable in 1.28 though.
This is must-have as current approach doesn't guaranteed to work.

[TimDiekmann]

It's stabilized on 1.28 but the stable branch is 1.26 currently.

[zakarumych]

I believe it is 1.27 (at least that's what rustc --version say)

[TimDiekmann]

Oh, right. However, not 1.28 though :)

[zakarumych]

It's time.