fix(just): widen to the unscoped suite when a diff outgrows argv - #3242
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`_changed` prints the changed-file list and every hop of the dispatch takes it as one argument (`just _tools "$files"`, `just js check "$files"`, `just rs check-changed "$files"` -> `just rs _select "$FILES"`). just exports recipe parameters into the child's environment, so it travels as a single execve string, and Linux caps one string at MAX_ARG_STRLEN (32 pages) however large ARG_MAX is. Past that every hop dies with E2BIG, which just reports as exit code 126 and "Argument list too long", naming neither the diff nor the recipe that could not receive it. Budget the list and print the `ALL` sentinel the repo already uses when it does not fit, so `check`, `fix`, and `test` fall back to `check-all` / `fix-all` / `test all`, which pass no list at all. Batching cannot work here: each consumer needs the whole list for one scoping decision, so a chunked list would silently under-select. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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WalkthroughThe Merge Risk: 🟡 Moderate · up to The PR adds a fallback for oversized changed-file lists, but the regression test can fail depending on the checkout state, and UTF-8 filenames can still exceed the intended byte limit because the size check counts characters. These bounded correctness issues should be fixed before merging. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
Full details: Docstring CoverageExplanation No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (3 skipped: 3 unsupported.) ✨ Finishing Touches✨ Simplify code
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Inline comments:
In `@justfile`:
- Line 132: Update the _changed-test assertion in _check-common so it uses an
isolated nonempty fixture or deterministic changed-file input instead of the
checkout’s actual diff; ensure the one-byte boundary case makes just _changed ""
1 return ALL while preserving the intended assertion.
- Line 105: Update the LIMIT comparison in the files-handling logic to measure
files by byte count rather than character count, using wc -c for the comparison
while preserving the existing threshold and control flow.
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`_changed-test` asserted that `just _changed "" 1` prints ALL, which only holds when the working tree has a diff. cache.yml runs `just check-all` on a clean `main` checkout to warm the shared Rust cache, where the list is empty and the assertion aborts `_check-common` before the suite runs, failing the one job allowed to write that cache. Split the size decision into `_changed-cap`, a pure function of a byte count, so the test drives it with synthetic sizes instead of the ambient diff. The end-to-end assertion stays, guarded on there actually being a diff. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
`${#files}` counts characters under a UTF-8 locale while execve counts bytes,
so a path set of 3-byte characters read as a third of its real size and could
sail past a budget it actually blows, back into the E2BIG this guards against.
Feed the list to `_changed-cap` on stdin and measure it with `wc -c`. Stdin is
both the only channel that can carry an oversized list and the only honest way
to measure one.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Inside `[[ ]]` the exit status of a command substitution is discarded, so a rejected budget left `_changed` printing a list that never got budgeted, which on a large diff walks straight back into the E2BIG this recipe prevents. Assign first so `set -e` sees the failure, and assert it in `_changed-test`. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Reviewed commit: 31dfdeba13
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A checkout whose only change is a one-character root path yields a one-byte list, which a one-byte budget does not exceed, so `_changed` returned the list instead of ALL and the assertion failed every `just check`. Zero is below every nonempty list. Covered synthetically too, so the boundary no longer depends on what the checkout happens to hold. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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@codex review Head is now 8067b45. Since your review of 31dfdeb the only change is the one you asked for: the end-to-end cap assertion budgets at 0 instead of 1 (a one-character root path is a one-byte list that a one-byte budget does not exceed), plus a synthetic assertion so that boundary no longer depends on the checkout. Please confirm the delta before this lands. (Written by Claude Opus 5) |
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Summary
_changedprints the changed-file list, and every hop of the dispatch takes it as one argument:just _tools "$files",just js check "$files",just rs check-changed "$files"->just rs _select "$FILES". just exports recipe parameters into the child's environment, so the list travels as a single execve string, and Linux caps one string atMAX_ARG_STRLEN(32 pages = 131072 bytes) however largeARG_MAXis (macOS caps the total at 1 MiB). Past that, every hop dies withE2BIG, which just reports as exit code 126 and "Argument list too long" -- naming neither the diff nor the recipe that could not receive it. PR feat(net)!: announcements are prefix routes #3225 hit this locally and in both CI jobs after accidentally including a 24k-file fuzz corpus, which buried the real problem._changed-capreads the list on stdin and prints theALLsentinel the repo already uses when it does not fit in one argument.check,fix, andtest defaultbranch on it intocheck-all/fix-all/test all, the paths that pass no list at all.grep -qElanguage-scope tests,_select's seed -> dependent walk), so a chunked list would silently under-select. Widening never under-checks, and a diff that large selects most of the workspace anyway.${#var}counts characters under a UTF-8 locale while execve counts bytes, so a path set of 3-byte characters would read as a third of its real size.MAX_ARG_STRLEN, leaving headroom for the rest of argv and env. Roughly 1500 paths. The fast path for normal diffs is unchanged.Public API changes
None. Build tooling and docs only; no Rust or TS surface is touched.
Test plan
New
_changed-test, wired into_check-commonso it runs in bothcheckandcheck-all, following the existing_select-testidiom. It drives_changed-capwith synthetic stdin fixtures, so it behaves identically in a dirty worktree, a clean checkout, and CI:ALL; at budget and empty must not;MAX_ARG_STRLEN;justargv hop (the operation that was failing);ALL-- guarded on there being a diff at all, and budgeted at 0.Verified it bites:
just _changed-test 200000fails on theMAX_ARG_STRLENassertion.Reproduced the original failure by creating 30k untracked files (1.8 MB of paths). Before:
just check,just test, andjust fixall exited 126 with "Argument list too long". After: all three printchanged: 1800032 bytes of paths exceeds the 65536 budget; selecting everythingand proceed into the unscoped suite.Also verified the fast path is untouched -- a normal diff prints the same list as before, an empty diff still yields empty output and the "nothing changed" message, and the pre-existing "root orchestration changed" fallback still fires.
Review follow-ups
Four findings, all in the test rather than the fix, each reproduced before being fixed and each given regression coverage:
_changed-testdepended on the checkout having a diff (Codex, then CodeRabbit).cache.ymlrunsjust check-allon a cleanmaincheckout to warm the repo's only shared Rust cache, where the list is empty; the assertion would have failed that job. Fixed in 5931590 by splitting_changed-capout and driving it with synthetic input.${#files}returned 3 for a 9-byte string, so UTF-8 paths under-counted 3x and could sail past a budget they actually blow. Fixed in c970897 by measuring on stdin withwc -c.[[ ]]a command substitution's exit status is discarded, so_changedreturned an unbudgeted list and exited 0 -- straight back into the E2BIG this prevents. Fixed in 31dfdeb.1 > 1is false. Fixed in 8067b45 by budgeting at 0, which is below every nonempty list.Cross-Package Sync
No rows apply (no wire format,
moq-ffi, or CLI surface changed).CLAUDE.mdgains one line documenting the fallback, since it is the file that describes the diff-aware scoping.(Written by Claude Opus 5)