Provide pushforward methods for Kokkos::View indexing

[gojakuch]

Previously, we relied on automatically generated pushforwards for these operator calls, but this solution is way safer and should work for more machines and Kokkos versions.

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.34%. Comparing base (6f4b081) to head (29127cd).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1061   +/-   ##
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  Coverage   94.34%   94.34%           
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  Files          55       55           
  Lines        8311     8311           
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  Hits         7841     7841           
  Misses        470      470           

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[kliegeois]

This looks great but I would add a last version with 8 arguments as views can have up to 8 dimensions. Thanks!

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[kliegeois]

@gojakuch now that I am thinking about it, the code of the PR needs to be changed.

In Kokkos, the index type is templated with a different template for each indices. Example:

  // rank 4
  template <typename I0, typename I1, typename I2, typename I3>
  KOKKOS_INLINE_FUNCTION constexpr size_type operator()(I0 const& i0,
                                                        I1 const& i1,
                                                        I2 const& i2,
                                                        I3 const& i3) const {
    return i0 + m_dim.N0 * (i1 + m_dim.N1 * (i2 + m_dim.N2 * i3));
  }

The merged code works only if I0, ... I3 are the same.
Could you fix that and add a test that uses a view indexing of at least 2 dimensions where one is a int and one is a size_t index? Thanks!

[gojakuch]

@kliegeois I see. I'll open a PR today then

[kliegeois]

Thanks a lot @gojakuch !