Mathieu Benoit
c3916d3982
Three stage-2 builds -- brotli, libseccomp, meson -- stopped on /usr/bin/python: No module named build and building python-build means running `python -m build`. Its dependencies are the same cycle: packaging and pyproject-hooks are flit_core-backed, installing a wheel wants python-installer, and none of the six exist yet. On the host the cycle was already broken -- apt had python3-build -- so stage 1 never met it. Breaking it there again is not possible: apt has no python3-flit-core at all, so the backend all six need cannot be installed on the host by any means. Arch had already solved it, in the PKGBUILDs: `_bootstrap=1` selects a vendored builder that needs none of the six. That is upstream's supported path through exactly this situation, and it replaced a half-written alternative here -- three bespoke hooks calling `python -m flit_core.wheel` and unzipping into $pkgdir -- which would have reimplemented what the PKGBUILD already does properly. --- FR --- Trois constructions d'étage 2 — brotli, libseccomp, meson — se sont arrêtées sur /usr/bin/python: No module named build et bâtir python-build suppose d'exécuter `python -m build`. Ses dépendances sont le même cycle : packaging et pyproject-hooks passent par flit_core, installer une roue demande python-installer, et aucun des six n'existe encore. Sur l'hôte le cycle était déjà rompu — apt fournissait python3-build — donc l'étage 1 ne l'a jamais rencontré. Le rompre à nouveau là est impossible : apt n'a aucun python3-flit-core, donc le moteur dont les six ont besoin ne peut être installé sur l'hôte par aucun moyen. Arch l'avait déjà résolu, dans les PKGBUILD : `_bootstrap=1` sélectionne un constructeur embarqué qui n'a besoin d'aucun des six. C'est la voie prévue en amont pour exactement cette situation, et elle a remplacé une solution à demi écrite ici — trois hooks sur mesure appelant `python -m flit_core.wheel` puis dézippant dans $pkgdir — qui aurait réimplémenté ce que le PKGBUILD fait déjà correctement. Assisted-by: Claude Opus 5
54 lines
2.5 KiB
Bash
Executable file
54 lines
2.5 KiB
Bash
Executable file
#!/usr/bin/env bash
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# Arch's own escape hatch for the Python packaging cycle. Sourced by the six
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# hooks that need it; not a hook itself.
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#
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# THE CYCLE. Three stage-2 builds -- brotli, libseccomp, meson -- stopped on
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#
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# /usr/bin/python: No module named build
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#
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# and building python-build means running `python -m build`, which is
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# python-build. Its dependencies are the same: packaging and pyproject-hooks are
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# flit_core-backed, installing a wheel wants python-installer, and none of them
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# exist yet.
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#
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# On the host the cycle was already broken -- apt had python3-build -- so stage 1
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# never met it. Trying to break it there again failed for a reason worth
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# recording: `apt-cache policy python3-flit-core` returns no candidate at all.
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# Ubuntu does not package it, so the backend every one of these needs cannot be
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# installed on the host by any means. Our own python-flit-core builds fine, but
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# building a package is not installing it.
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#
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# ARCH ALREADY SOLVED THIS, and the solution is in the PKGBUILDs:
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#
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# if (( _bootstrap == 0 )); then
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# python -m build -wn --skip-dependency-check
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# else
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# cd python-bootstrap
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# python -m bootstrap.build
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# fi
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#
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# python-bootstrap is a vendored builder that needs none of the six. Setting
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# _bootstrap=1 is upstream's supported path through exactly this situation --
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# far better than the alternative that was half-written here first, which was a
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# per-package hook calling `python -m flit_core.wheel` and unzipping the result
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# into $pkgdir by hand. That would have been three bespoke reimplementations of
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# something the PKGBUILD already does properly.
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#
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# It also means these build on the HOST, where they had failed, so they need no
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# stage-2 special handling at all.
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set -euo pipefail
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python3 - <<'ZZPY'
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import io
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s = io.open("PKGBUILD", encoding="utf-8").read()
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old = "_bootstrap=0"
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assert s.count(old) == 1, "python bootstrap: expected one _bootstrap=0, got %d" % s.count(old)
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s = s.replace(old, "_bootstrap=1 # see patches/pkgbuild/lib-python-bootstrap.sh", 1)
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io.open("PKGBUILD", "w", encoding="utf-8").write(s)
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ZZPY
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grep -q "^_bootstrap=1" PKGBUILD || {
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echo "python bootstrap: _bootstrap was not switched" >&2; exit 1; }
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# The branch it selects must actually exist, or the switch silently builds
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# nothing -- these PKGBUILDs are not required to have both halves.
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grep -q "bootstrap.build" PKGBUILD || {
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echo "python bootstrap: no bootstrap.build branch in this PKGBUILD" >&2; exit 1; }
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echo "$(basename "$PWD"): _bootstrap=1 (Arch's vendored builder)"
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