Pin CI to a known-good Mojo nightly; check drift weekly - #6
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Mojo's stdlib made String.write an instance method -- both overloads now take `mut self` -- so the old static form no longer resolves and the test module fails to parse: test/test_errors.mojo:15:18: error: no matching function in call to 'write' note: candidate not viable: value passed to mutable argument 'self' must be mutable String.__init__ takes a variadic pack of Writable arguments, and Error conforms to Writable, so String(e) is the direct replacement and produces the same bytes. Nothing in src/ used the old form; this is test-only. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Both workflows installed `mojo` from the nightly index unpinned, so every run resolved whatever nightly was current. That is why this repo went green on 7/29 and red on 7/31 with no commits in between -- a frozen library's CI decayed on its own, and the breakage surfaced on an unrelated docs PR. CI now installs exactly the nightly the repo is known to pass on. Upstream churn can no longer turn a green repo red without a commit. Pinning alone would trade one problem for a worse one: silence. So test.yml also runs weekly against the LATEST nightly. That run is advisory -- it fires on main, so it never gates a PR -- and on failure it opens (or comments on) a drift issue, because a red X on the Actions tab of a repo nobody is watching is not a signal. The weekly check reuses test.yml rather than living in its own file. A separate workflow would have to duplicate this repo's bespoke test steps and would drift out of sync with them. docs.yaml is pinned but not scheduled -- it deploys Pages, and a weekly redeploy is not wanted. `mojo doc` compiles the sources, so the test job catches the same stdlib breakage anyway. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This was referenced Jul 31, 2026
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Both workflows installed
mojofrom the nightly index with--prerelease allowand no version pin, so every run resolved whatever nightly was current. That's the root cause of the breakage fixed in #5: this repo went green on 7/29 and red on 7/31 with no commits in between, and it surfaced on an unrelated docs PR.Pin.
MOJO_VERSION: 1.0.0b3.dev2026073014— the nightly all 11 repos went green on today. Pushes and PRs install exactly it, so upstream churn can't turn a green repo red without a commit.Weekly drift check. Pinning alone trades one problem for a worse one — silence. So
test.ymlalso runs Mondays against the latest nightly:main, so it never gates a PR.Why this reuses
test.ymlinstead of a new workflow file. Each repo's test steps are bespoke — this one runs 5 distinct test modules plus a bench. A separatenightly-latest.ymlwould have to duplicate them and would silently drift out of sync. One workflow, one branch ongithub.event_name.docs.yamlis pinned but not scheduled — it deploys Pages and a weekly redeploy isn't wanted.mojo doccompiles the sources, so the test job catches the same stdlib breakage regardless.Verified before pushing: both files parse as valid YAML, and the drift step's script was extracted from the parsed YAML and executed with
ghstubbed — it creates an issue when none exists and comments when one does. The issue body is built with a heredoc specifically so the YAML block indentation doesn't leak in and render the whole thing as a markdown code block.When this fires: fix the breakage, then bump
MOJO_VERSIONin both files to the nightly that passes.🤖 Generated with Claude Code