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Mirrors upstream's cibuildwheel + scikit-build-core recipe as-is (no CIBW_ENVIRONMENT/CIBW_TEST_COMMAND overrides): pyproject.toml already sets SKBUILD_CMAKE_ARGS (FETCH_ZLIB_NG=ON among others) and the unittest-based test-command, so cibuildwheel picks both up unmodified from the checkout. zlib-ng (fetched via CMake FetchContent at build time) has confirmed riscv64 RVV dispatch support from the in-flight python-zlib-ng port. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Az13NcXsVZzzxXmaxxUEy7
CMakeLists.txt's find_package(nanobind 2.4.0 CONFIG REQUIRED) rejects nanobind 3.x as a version mismatch, but pyproject.toml's build-system.requires carries no upper bound. nanobind 3.x requires Python >=3.10, so this reproduces on any architecture building cp310+ - it just never surfaced on upstream's own py3.9 leg. Constrain both the top-level and isolated build envs via CIBW_BEFORE_ALL + PIP_CONSTRAINT/PIP_BUILD_CONSTRAINT rather than disabling isolation. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Az13NcXsVZzzxXmaxxUEy7
cibuildwheel parses CIBW_ENVIRONMENT with bashlex; the unquoted semicolon-separated CMake arg list was read as multiple shell statements instead of one assignment, so cibuildwheel rejected the whole option as malformed. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Az13NcXsVZzzxXmaxxUEy7
stb_sprintf.h's stbsp__uintptr allowlist has no riscv64 entry, so it falls back to a 32-bit unsigned int on a 64-bit-pointer platform; every (stbsp__uintptr)ptr alignment check then narrows a pointer to 32 bits, which GCC 14 rejects as a hard error rather than a warning. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Az13NcXsVZzzxXmaxxUEy7
CMakeLists.txt enables CMAKE_INTERPROCEDURAL_OPTIMIZATION for Release builds by default, and already turns it off for the bundled zlib-ng because "IPO has been reported to mess it up leading to illegal-instruction crash" on some platforms. gemmi's own code hits that same crash on riscv64: the wheel builds and installs fine, but the very first unittest dies with SIGILL. Disable LTO globally rather than only where upstream anticipated the problem. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Az13NcXsVZzzxXmaxxUEy7
Disabling project-wide LTO did not fix the riscv64 SIGILL (identical crash, same test, same instruction pointer class) - so that was the wrong culprit. The crash is in test_align.py's very first test, which is also the first to read a real file through zlib (a .pdb.gz), pointing at the fetched zlib-ng's RVV-accelerated chunkset/inflate kernels instead. Pass -DWITH_RVV=OFF to fall back to zlib-ng's portable C implementation. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Az13NcXsVZzzxXmaxxUEy7
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gemmi0.7.5Compiles gemmi's C++ macromolecular-crystallography library and its nanobind Python bindings. Upstream publishes no riscv64 wheel.
Mirrors upstream's
wheels2.yml.Differs from upstream
Testing
License: OK