pack: fill every placeholder in multi-argument error messages - #38743
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Updated 8:05 PM PT - Aug 14th, 2026
❌ @robobun, your commit 76196cb has 1 failures in
🧪 To try this PR locally: bunx bun-pr 38743That installs a local version of the PR into your bun-38743 --bun |
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Status: ready for review at 9948148 (rebased onto main, no changes to the diff). Review threads addressed. Reproduced on the current release ( CI: the previous run's only hard failure was Overlap with #38739 is described in the description and in the comment below the duplicate notice. |
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WalkthroughChangesThe change tightens template substitution handling, reformats bun pack error arguments, and adds tests for destination path length, conflicting options, and directory-based ignore-file errors. Bun pack diagnostics
Suggested reviewers: Merge Risk: 🔵 Low · up to The PR fixes several malformed pack error messages and reports the correct bundled file name. It is mergeable with owner awareness that the destination-length regression test may not reliably exercise the byte-based path-limit case when temporary paths contain non-ASCII characters. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
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Actionable comments posted: 3
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Inline comments:
In `@src/runtime/cli/pack_command.rs`:
- Line 2716: Add a regression test covering the bundled-file path where
file.stat() fails, and assert that the resulting diagnostic includes item.path.
Reuse the existing pack-command test setup and failure-reporting assertions
without changing production behavior.
In `@test/cli/install/bun-pack.test.ts`:
- Around line 1435-1454: Replace the loop over ignoreFile in the parameterized
test section with describe.each(), keeping separate cases for .gitignore and
.npmignore. Preserve the existing test setup, packExpectError invocation, and
file-specific error assertions while deriving the test name and paths from the
describe.each parameter.
- Around line 350-351: Update the destination-length calculation near pathMax to
use Buffer.byteLength(packageDir) instead of packageDir.length, and replace the
literal 100 with a clearly named destinationHeadroom constant before computing
dest. Preserve the existing pathMax-dependent allocation and join behavior.
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Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
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src/bun_core/output.rssrc/runtime/cli/pack_command.rstest/cli/install/bun-pack.test.ts
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This PR may be a duplicate of:
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Not a duplicate, though the overlap is real and is noted in the description. #38739 is about where relative What only this PR covers:
If #38739 lands first, this PR rebases down to those items plus a trivial conflict in the |
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LGTM — focused error-message fix with tests and a debug-time guard for the bug class.
What was reviewed:
- Verified the three
format_args!→ tuple conversions match placeholder counts (2, 2, 5) and follow the existing pattern used elsewhere inpack_command.rs. - Checked
substitute_template's release behavior is unchanged (theif filledguard remains); the newdebug_assert!only fires in debug builds. - Confirmed the bundled-dep stat error now prints
item.pathlike the sibling loop at line 2656;itemis in scope. - The comment-cop flags on
output.rswere addressed by the two follow-up commits that shortened the doc comments.
Extended reasoning...
Overview
The PR fixes four malformed error messages in bun pm pack (src/runtime/cli/pack_command.rs): three sites passed a single format_args! bundle to Output::err/err_generic where the template had multiple placeholders, so all values landed in the first slot and the rest rendered empty; a fourth printed a file descriptor instead of a path. It adds a debug_assert! in substitute_template (src/bun_core/output.rs) so future placeholder/argument mismatches crash in debug builds instead of silently rendering wrong. Two stale doc comments in output.rs are corrected. Three new tests plus one strengthened test cover the fixed messages.
Security risks
None. This is error-message formatting for a CLI subcommand. No parsing of untrusted input, no auth/crypto, no changes to file-writing or path-resolution logic.
Level of scrutiny
Low-to-medium. The pack_command.rs changes are mechanical (format_args!("{} {}", a, b) → (a, b)) and match the pattern already used by edit_root_package_json in the same file. The file.handle → item.path swap mirrors the identical loop directly above it. The output.rs change adds a debug_assert! with release behavior explicitly preserved (the if filled { argi += 1 } guard is unchanged), and the author scanned all 570 call sites to confirm no existing site would trip it.
Other factors
- Tests: 3 of 4 sites have direct coverage that fails on the current release and passes here; the fourth (bundled-dep
fstatfailure) is reasonably argued as untestable —fstaton a just-opened fd cannot be made to fail from a test. - The
--destination too longtest correctly sizes in bytes (Buffer.byteLength) and uses platform-appropriate PATH_MAX values (4096 Linux, 1024 macOS); Windows is skipped with a stated reason. - The github-actions comment-cop flagged a long comment in
output.rstwice; the two follow-up commits (aea5f2ff,76196cbd) shortened it, and the current diff shows no remaining long comment. - CodeRabbit's suggestions were resolved with reasonable explanations (loop matches adjacent test's style;
fstatfailure not testable). - Overlap with #38739 is documented as merging cleanly in either order.
Three pack errors passed a single format_args! to a template with two or more placeholders. Output::err and err_generic treat a fmt::Arguments as one positional, so every value landed in the first placeholder and the rest rendered empty: filename "a.tgz out" and destination "" archive destination name too long: ".../pkg-1.0.0.tgz/" EISDIR: failed to read .npmignore /pkg/sub/.npmignore at: "" Pass tuples instead, like the other multi-argument messages in this file. The bundled dependency loop's stat error printed the file descriptor number instead of the path; print the path like the loop above it. substitute_template now fails a debug assertion when a template has more placeholders than the arguments it was given, so a call site like these crashes in debug builds instead of printing a plausible-looking message. These three were the only such sites in src/.
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LGTM — mechanical fix converting three format_args! sites to tuples so each placeholder gets its own argument, plus one drive-by that swaps a file descriptor for the path in a sibling error.
What was reviewed:
- Verified each tuple's arity now matches its template's placeholder count (2, 2, 5) and the bundled-loop stat error mirrors the open error directly above it at pack_command.rs:2705.
- Checked the
debug_assert!insubstitute_template— release-inert, format args lazily evaluated, andargs.len()is defined on everyFmtTupleimpl including(). - Confirmed the doc-comment corrections match what the code actually does (specs inside
{...}are consumed, not passed through; out-of-range placeholders emit nothing, not a literal{}). - The three new/tightened tests each assert the specific rendered message; the one untested line (bundled fstat) is correctly noted as unreachable from a test.
Extended reasoning...
Overview
Four call sites in src/runtime/cli/pack_command.rs passed a single format_args! bundle to Output::err / Output::err_generic templates that have multiple {} placeholders. Because fmt::Arguments implements FmtTuple as a single positional, everything landed in the first slot and the rest rendered as empty. Three sites (tarball_destination ×2, ignore_file_fail) are converted to tuples matching the pattern already used elsewhere in this file; the fourth (bundled-dep stat error) had a separate bug — it printed file.handle (an fd) instead of item.path — and now matches the open-error line just above it. src/bun_core/output.rs gains a debug_assert! in substitute_template that fires when a placeholder finds no argument, plus two doc-comment corrections. test/cli/install/bun-pack.test.ts gains two new tests and tightens one existing test to assert the exact message.
Security risks
None. This touches error-message rendering on failure paths in bun pm pack; no parsing of untrusted input, no auth/crypto/permissions, no change to success-path behavior.
Level of scrutiny
Low. The fix is mechanical — the tuple form is already the established pattern in this file (edit_root_package_json uses it), and the diff is a straight swap of format_args!("{} {}", a, b) for (a, b). The debug_assert! is compiled out of release builds; the PR description states the author scanned all 570 Output::err* sites and these three were the only mismatches, and verified the assertion fires on the unfixed call site and not with the fix applied. The doc-comment edits are correct against the implementation I read.
Other factors
All bot review threads are resolved: the CodeRabbit request for a stat-error test was withdrawn (fstat on a just-opened fd cannot be made to fail deterministically), the for-loop-vs-describe.each nit matches the adjacent test's style, and the two comment-cop pings were addressed by trimming the output.rs doc comment (now one line, with the actionable hint moved into the assertion message). CI's only failure was test-http-chunk-problem.js, a known main breakage picked up by rebase per the status comment. The overlap with #38739 is documented and the shared hunks are byte-identical. Tests cover 3 of 4 changed messages; the fourth is reasonably argued as untestable and now matches its sibling one-placeholder call at line 2705.
2 participants
Problem
bun pm pack --filename=a.tgz --destination=outprintserror: cannot use both filename and destination at the same time with tarball: filename "a.tgz out" and destination "": both values land in the first quoted slot and the second is empty.".../pkg-1.0.0.tgz/") for the same reason.EISDIR: failed to read .npmignore /pkg/sub/.npmignore at: ""instead ofEISDIR: failed to read .npmignore at: "/pkg/sub/.npmignore".src/runtime/cli/pack_command.rs(tarball_destination, twice, andIgnorePatterns::ignore_file_fail) handOutput::err_generic/Output::erroneformat_args!holding every value, while the template has two (or five) placeholders. Afmt::Argumentscounts as a single positional (src/bun_core/output.rs,impl FmtTuple for fmt::Arguments), so placeholder 0 receives everything andsubstitute_templaterenders the remaining placeholders as nothing.bundledDependenciesentry loop inpack()putsfile.handleinto its "failed to stat file" error, so it would readfailed to stat file: "7"(a file descriptor) instead of naming the file. The entry loop directly above it prints the path.Fix
edit_root_package_json) already do. The bundled loop's stat error printsitem.pathlike the loop above it.substitute_templatenow fails adebug_assert!when it reaches a placeholder after the arguments have run out. Release builds are unchanged (debug_assert!); debug builds, which is what the test suite runs, crash at the offending call site instead of printing a plausible-looking message.Output::err/err_genericcall sites insrc/(placeholders in the template literal against the arity of the argument) found these three as the only ones with more placeholders than arguments, so the assertion only fires on a new instance.output.rshunk, andbun pm pack --filename=a.tgz --destination=outpanics withtemplate has more placeholders than the 1 arg(s) passed for it: "cannot use both filename and destination ...". With the whole change it prints the correct message.fstatfailure cannot be provoked from a test (the file was opened a moment earlier), so that one line is untested.test/cli/install/bun-pack.test.ts.--filename and --destinationnow asserts the message; new:--destination with no room left for the tarball name(POSIX only, it sizes the destination against PATH_MAX, which a Windows command line cannot reach) andreports which .gitignore/.npmignore could not be read(a directory where the ignore file is expected, inside a subdirectory so the directory part of the message is exercised; the current release prints the same EISDIR/read message on Windows, so the assertion is not platform-gated). These 4 fail on the current release and pass with this change; the whole file (79 tests) passes with it.--destination/--filename) also switches the twotarball_destinationmessages to tuples. Those hunks are identical, sopack_command.rsmerges cleanly in either order (checked withgit merge-tree). Both PRs rewrite the--filename and --destinationtest the same way; the one textual conflict is that pm pack: resolve relative --destination and --filename against the invoking directory #38739 adds its tests directly below it.Background
Output::err(name, template, args)andOutput::err_generic(template, args)insrc/bun_core/output.rstake a template string with{}placeholders and animpl FmtTuple:(), a tuple of up to eightDisplayvalues, or onefmt::Arguments.substitute_templatewalks the template at runtime and fills each placeholder with the next entry. Thefmt::Argumentsform exists for the common one-placeholder message (format_args!("{}", bstr::BStr::new(path))); it is one entry no matter how many values went into it.pretty!family of macros, which expand toformat_args!and so are checked by the compiler, this path has no compile-time check that the template and the arguments agree. The new assertion is its debug-time equivalent.pack()writes entries in two loops: the package's own files, then the files of itsbundledDependencies. The second loop opens files through theDirAPI and so holds aFile(whosehandleis the descriptor) rather than a path-carrying error, which is how the descriptor ended up in the message.