nested namespace holding kk mkl implementation

[lucbv]

@maartenarnst
A compilation error occurs when compiling Trilinos/kokkos-kernels when both mkl and rocsparse are enabled.

/Trilinos-sources/packages/kokkos-kernels/sparse/tpls/KokkosSparse_spmv_bsrmatrix_tpl_spec_decl.hpp:35:7: error: no member named 'mode_kk_to_mkl' in namespace 'KokkosSparse::Experimental::Impl::KokkosSparse::Impl'; did you mean '::KokkosSparse::Impl::mode_kk_to_mkl'?

PR #2100 proposed an initial fix and was then superceded by PR #2134 waiting for feedback on whether this is now working properly or if more work is needed? In general I would expect that pre-qualifying the namespace with :: to indicate the top level should not be necessary and would be to permissive for macro usage outside of Kokkos Kernels.

[maartenarnst]

Hi @lucbv,

Thanks for your work on this issue!

I've just made the changes from PR #2134 in our Trilinos build. Unfortunately, the issue remains.

The error message reads as:

INFO:root:#21 388.7 /Trilinos-sources/packages/kokkos-kernels/sparse/src/KokkosSparse_Utils_mkl.hpp:128:5: error: no member named 'mkl_internal_safe_call' in namespace 'KokkosSparse::Impl::KokkosSparse::Impl'; did you mean simply 'mkl_internal_safe_call'?
INFO:root:#21 388.7     KOKKOSKERNELS_MKL_SAFE_CALL(mkl_sparse_destroy(mtx));
INFO:root:#21 388.7     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
INFO:root:#21 388.7 /Trilinos-sources/packages/kokkos-kernels/sparse/src/KokkosSparse_Utils_mkl.hpp:69:3: note: expanded from macro 'KOKKOSKERNELS_MKL_SAFE_CALL'
INFO:root:#21 388.7   KokkosSparse::Impl::mkl_internal_safe_call(call, #call, __FILE__, __LINE__)
INFO:root:#21 388.7   ^~~~~~~~~~~~~~~~~~~~

It appears that the compiler is still looking for mkl_internal_safe_call in the wrong (nested) namespace. Do you think we should re-introduce the initial fix with the pre-qualification with ::? Or do you think of a good alternative?

Thanks in advance!