ci: re-add clang-17 to the cpu matrix (scoped OpenMP runtime) - #18
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clang-17 was dropped (6bc79a9) because the shared apt-get install line carried libomp-17-dev for every matrix job; when that package failed to resolve, the install step died in all jobs (including gcc), reddening the whole matrix. The failure was packaging, not a C++20 source divergence. Re-add clang-17 and move its LLVM OpenMP runtime into a clang-only step (if: startsWith(matrix.compiler.cc, 'clang')) so a clang-specific package can never block the gcc jobs again. Closes #15.
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Restores two-compiler (gcc + clang) CPU coverage in CI. Closes #15.
Root cause
clang-17 was dropped in
6bc79a9under the theory of a C++20 source incompatibility, but the drop commit itself records the real cause: the sharedapt-get installline carriedlibomp-17-devfor every matrix job, so when that package failed to resolve the install step died in all jobs — including gcc — reddening the whole matrix. Local clang syntax-checks of theomp/sources compile clean, corroborating that the source was never the problem.Fix
{ cc: clang-17, cxx: clang++-17 }to thecpumatrix.if: startsWith(matrix.compiler.cc, 'clang')) installingclang-17 libomp-17-dev, so a clang-specific package can never block the gcc jobs again.libomp-17-dev(1:17.0.6) is available on noble.Verification
This PR's own CI is the verification: clang-17 Debug+Release must configure (FindOpenMP), build, and pass ctest, with gcc-13 jobs still green.