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…d the JS builtins The YAML parser only runs as Parser<Utf8>. Remove the Latin1 and Utf16 encodings, the EncodingKind tag, the Utf16-only trait methods, and the match arms that selected between them. Remove BlobExt::transfer, Channel::close in the parallel test runner, Default for URLFormatter, the From<_> for PredefinedColor conversions, the kBindStreamsLazy console method, and byteLength in the vendored base64-js fallback. None of these has a caller.
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Updated 3:05 AM PT - Aug 31st, 2026
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Included review availability: Your plan provides up to 10 included reviews per hour; 6 remain after this review. WalkthroughChangesThe pull request removes obsolete formatting and color conversion APIs, simplifies the Base64 fallback helper, and changes YAML parsing to use UTF-8 only. API and encoding cleanup
Suggested reviewers: Merge Risk: ⚪ Minimal · up to This change removes unused parser, formatting, color-conversion, and fallback code without a supplied indication of changed user-visible behavior or a current correctness issue; no actionable merge-blocking risk remains after normal checks and review. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
Full details: Description checkExplanation The description explains the problem, lists the fixes, documents verification steps, and provides relevant background and scope notes. It does not use the template headings exactly, but it includes the required information and is complete. Comment |
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Actionable comments posted: 1
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Inline comments:
In `@src/parsers/yaml.rs`:
- Around line 5264-5267: Update the Encoding::literal documentation to describe
UTF-8 byte inputs and clarify that per-unit widening is valid only when Unit ==
u8; update the Encoding::ch documentation with the same constraint or pass
s.as_bytes() directly. Apply the documentation/API clarification for both
affected sites in src/parsers/yaml.rs: lines 5264-5267 and 5330-5331.
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📒 Files selected for processing (7)
src/bun_core/fmt.rssrc/css/values/color.rssrc/js/builtins/ConsoleObject.tssrc/node-fallbacks/vendor/base64-js.jssrc/parsers/yaml.rssrc/runtime/cli/test/parallel/Channel.rssrc/runtime/webcore/Blob.rs
💤 Files with no reviewable changes (5)
- src/js/builtins/ConsoleObject.ts
- src/bun_core/fmt.rs
- src/node-fallbacks/vendor/base64-js.js
- src/runtime/webcore/Blob.rs
- src/css/values/color.rs
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Additional findings (outside the current diff — GitHub can't attach inline comments there):
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src/runtime/cli/test/parallel/Channel.rs— nit: Theadopt_pipedoc comment still says "The pipe is closed explicitly inclose()/Drop", but this PR removesChannel::close(), leavingDrop(and the read-error path) as the only teardown sites. Fix: update the comment to reference onlyDrop.Extended reasoning...
Line 278-280 of the post-change file reads: "The pipe is closed explicitly in
close()/Drop, and both sides exit via Global.exit / drive() returning, so the extra ref never holds the process open." Theclose()method this refers to is deleted at the former lines 494-519 by this same diff. On the base branch the comment was accurate; after merge it names a method that no longer exists. A future reader auditing why the ref'd pipe doesn't hold the process open will look for aclose()that isn't there. Purely a doc-drift nit — no runtime behavior change, sinceDrop(lines 553-574) still performsuv::Pipe::close_and_destroyandclose()had no callers anyway.Verification: nit — The doc comment on
adopt_pipeat src/runtime/cli/test/parallel/Channel.rs:278-280 still reads "The pipe is closed explicitly inclose()/Drop", but this same diff deletesChannel::close()(former lines 494-519). OnlyDrop(impl at line 553) remains as the teardown site the comment should name. The comment was accurate on the base branch and is made stale by this PR, so it…
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LGTM — purely subtractive dead-code removal with no behavior change on any live path.
What was reviewed:
- Confirmed
Parser<Enc>is only ever instantiated asParser<Utf8>; each collapsedmatch Enc::KINDarm is byte-identical to its formerUtf8branch, and theEnc::literaldoc/cap update correctly tracks the now-unconditional non-ASCII UTF-8 escape bytes. - Grepped for callers of every removed item (
URLFormatter::default,kBindStreamsLazy, base64-jsbyteLength,BlobExt::transfer,Channel::close, thePredefinedColorFromimpls) — none exist. - Verified
Channel'sDropalready performs the pipe/socket teardownclose()did, and that dropping theUvHandleimport is sound becauseis_closing()was its only use.
Extended reasoning...
Overview
This PR removes ~366 lines of unreachable code across seven files with ~30 lines added (all of which are collapsed-in-place versions of the surviving Utf8 branches, plus doc-comment adjustments). The largest change flattens the encoding-generic YAML parser to its sole instantiated encoding by deleting the Latin1/Utf16 Encoding impls, the EncodingKind tag, and the unit_from_u16/as_u16_slice trait methods whose u8 bodies were unreachable!(). The remaining six items are standalone pub symbols with no callers anywhere in the workspace: a manual Default impl, seven From<_> conversions, a Symbol-keyed console builtin method, an unexported helper in a vendored fallback, a Channel::close that duplicated Drop, and a BlobExt trait method.
Security risks
None. No input handling, validation, auth, crypto, or protocol code is touched. Every hunk is a deletion of code no live path could reach; the only added lines are the surviving arms of removed matches, unchanged in content. The kBindStreamsLazy Symbol was module-local inside createConsoleConstructor, so no user code could ever have keyed into it. The vendored base64-js change removes a function that was never exported from the module.
Level of scrutiny
Moderate — dead-code removal is low-risk in principle, but the review guidance explicitly warns that pub items and trait impls escape rustc's dead-code lints and that inherent methods can silently resolve to trait/Deref targets. I therefore grepped the tree for every removed symbol and for Parser<Latin1|Utf16> instantiations, and read the Drop for Channel impl to confirm it covers everything the removed close() did (on Windows it null-swaps and close_and_destroys the pipe; on POSIX it closes the socket). The one path that could leave a pipe already-closing was close() itself, so Drop's unconditional close_and_destroy cannot double-close. The UvHandle trait import removal is correct because is_closing() was the only method it supplied.
Other factors
The PR description documents a rigorous discovery method (per-crate pub→pub(crate) rewrites iterated to a fixpoint across six targets and four build cfgs, plus a --gc-sections relink for trait impls) and lists the false-positive classes it excluded by hand — this matches what I'd expect for a safe sweep and is consistent with what the code shows. bun run rust:check-all and the relevant test suites are reported as passing. No third-party CHANGES_REQUESTED reviews are outstanding; the only inline threads were bot lint comments on earlier iterations, and a new commit landed after the last review. The change is mechanical enough that human review beyond this is unlikely to surface anything new.
robobun
changed the title
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Restructured after self-review:
Diff is now 4 files, +28 -295. |
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No test is added on purpose. Every removed item is unreferenced, so there is no behavior a test could observe before and after the change. The code paths this PR rewrites in place are already covered: |
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LGTM — with the scope narrowed to the four files, this is a clean mechanical removal.
What was reviewed:
URLFormatter::default(): no callers remain; all threebun_core::fmt::URLFormatter { … }sites insrc/runtime/server/mod.rspopulate every field.base64-js.js:byteLengthwas never exported (onlytoByteArray/fromByteArrayare);buffer.jsdefines its ownbyteLength. The file header already notes manual conversion from upstream, so the vendored-read-only concern doesn't apply.yaml.rs: no remainingEnc::KIND/EncodingKind/Latin1/Utf16references; each collapsed site matches its originalUtf8arm byte-for-byte;ParseResultError::UnexpectedEofis still constructed at yaml.rs:1864 via the non-ParseErrorpath, so removing only theParseErrorvariant is correct.From<_> for PredefinedColor: grepped forPredefinedColor::from/ typed.into()targets — none found; the linker-section methodology in the description is the right way to catch generic.into()sites.
Extended reasoning...
Overview
This PR removes dead code across four files: the Latin1/Utf16 encoding machinery in src/parsers/yaml.rs (collapsing six match Enc::KIND sites to their UTF-8 arms and dropping the EncodingKind enum, two Encoding impls, two trait methods, and the unconstructed ParseError::UnexpectedEof variant), seven unused From<_> for PredefinedColor impls in src/css/values/color.rs, the manual Default for URLFormatter in src/bun_core/fmt.rs, and the unexported byteLength helper in src/node-fallbacks/vendor/base64-js.js. Net +28/-295. Since the earlier reviewed revisions, the PR was narrowed — the Channel.rs hunk that drew a bot comment is no longer in the diff, and the description now names the overlap with other open PRs.
Security risks
None. This is pure deletion of code that is provably unreachable (only Parser<Utf8> is ever instantiated, per the entry point at src/parsers/yaml.rs:47) or has no caller. No parsing, validation, or bounds-checking logic is weakened; the surviving UTF-8 arms are byte-identical to what executed before.
Level of scrutiny
Moderate, focused on the "removed thing still has a caller" failure mode that REVIEW.md flags for public items and trait impls. Each removal was checked independently: URLFormatter construction sites all name every field; byteLength in base64-js was a non-exported local (only toByteArray/fromByteArray are exported, and buffer.js imports * as base64 without touching it); no PredefinedColor::from(...) or typed .into() sites exist; ParseResultError::UnexpectedEof is still constructed elsewhere so only the intermediate ParseError variant is dead; and yaml.rs has zero remaining references to the removed encoding symbols. The collapsed match arms were compared against the base to confirm they are the literal Utf8 arms with no edits.
Other factors
No CODEOWNERS pattern matches these paths. No outstanding CHANGES_REQUESTED reviews from humans — only bot comments, all on lines that either match the current state or on a file since removed from the diff. The vendored-file concern is moot: the file's own header states it was already manually converted to an ES module for tree-shaking, so it is not a pristine upstream copy, and the deleted function is not part of its export surface. The PR description's methodology (per-crate pub→pub(crate) narrowing across six targets and four build cfgs, plus --gc-sections for trait impls) is exactly what REVIEW.md asks for when deleting public items, and bun run rust:check-all was run. The follow-up to de-genericize Parser<Enc> is correctly deferred behind the five open YAML PRs it would conflict with.
Problem
Bun.YAML.parseonly ever instantiatesParser<Utf8>(src/parsers/yaml.rs:47), but the parser still carriesLatin1andUtf16encodings: twoEncodingimpls, anEncodingKindtag, two trait methods theu8impls markunreachable!(), andmatch Enc::KINDarms at six call sites. None of it can run.ParseError::UnexpectedEofis never constructed either.Default for URLFormatter, sevenFrom<_> for PredefinedColorimpls, andbyteLengthin the vendored base64-js fallback.Fix
Latin1andUtf16encodings.EncodingKind,Encoding::KIND,unit_from_u16andas_u16_slicego with them, and eachmatch Enc::KINDcollapses to itsUtf8arm. TheEncodingtrait andParser<Enc>stay (see Notes for the follow-up).ParseError::UnexpectedEofand the three items above.bun run rust:check-all(12 targets),cargo check --workspaceunder each custom build cfg,bun bd. Ran the yaml, css color, browser bundler and source-lint suites.Background
dead_code = "deny"andunreachable_pub = "deny", so rustc already rejects unused private items. It cannot see apubitem that no other crate imports. The candidates come from rewriting everypubtopub(crate)one crate at a time and reading thedead_codediagnostics, then checking the whole workspace with those rewrites so privacy errors show which items other crates use.Dereftarget. Every method candidate was also checked by hand for cross-crate call sites (Notes list what this caught).--gc-sections --print-gc-sections, as in Remove dead code: 92 trait impls nothing calls, across 29 crates #39795.Notes
How the candidates were found:
pubtopub(crate),cargo check -p <crate>with--cap-lints=warn, collect thedead_codespans (25,952 raw spans across 99 crates). Then rewrite only those spans in the full tree and iteratecargo check --workspace --keep-going, reverting any item that a privacy, resolution or type error proves another crate uses (102 rounds until clean). The loop was repeated onx86_64-pc-windows-msvc,aarch64-apple-darwin,aarch64-linux-android,x86_64-unknown-linux-musl,aarch64-pc-windows-msvcandx86_64-unknown-freebsd, and under thebun_debug/bun_asan/bun_codegen_embed/socket_fault_injectioncfgs, so an item used on one platform or in one build profile counts as live. 662 spans survived; 88 of them are already deleted by the 15 open dead-code PRs and were dropped.bun_runtime(the staticlib) was swept the same way with its generatedpub usere-exports kept public: 78 spans, almost all enum variants and struct fields.--gc-sections --print-gc-sectionsand without-rdynamic. Symbols dropped from every codegen unit and not present in the linked output gave 2,597 Rust candidates, of which 24 were hand-written trait impls. All but thePredefinedColorconversions were kept:Never: JobContextandNamedImportsType: Derefare needed for bounds,Bytes: Defaultis used on Windows,watcher::Error: From<bun_sys::Error>on macOS,Help: DefaultandSliceIteratorby unit tests,Dropimpls are never "called".src/js/**andsrc/node-fallbacks/**were checked member by member (class methods, symbol keys, builtins, unbundled files). The tree is clean apart frombyteLengthhere andkBindStreamsLazy, which Remove dead code from the JSC bindings, headers.h, the console builtin, and bun_jsc #40232 already removes.False positives that the compiler-driven pass produces, all excluded by hand:
Derefmethod: the SQLSocketHandler::{on_open, on_close, on_end}(theimpl_ns_socket_events_forward!macro calls them asSelf::on_open, which resolves to the trait method being implemented when the inherent one is private),uws_sys::h2::Response::request_body_ended,ProcessHandle::kill,ZStr::as_ptr,__IsFreeze::IS_FREEZE(inherent-const specialization),ThreadPool::Worker(inherent associated type that rustc reports unused although three call sites use it).MultiArrayListelement types (JSMeta,InputFile,Store::Entry,Store::Node,ServerComponentBoundary): read through generated column accessors, never by name.from_js_ref,css_name,platform_getand friends: macro expansions that are dead for one instantiation and live for another.host_fn_this_valueand thebindgen::Bindgen*types are emitted bysrc/codegen/generate-classes.tsandsrc/codegen/bindgenv2, andINTERNAL_MODULE_REGISTRY_FLAG,napi_status,ns_classandJSFunctionvisibility variants mirror C/C++ ABI values.Overlap with open PRs:
kBindStreamsLazy(ConsoleObject.ts),Channel::closeandBlobExt::transfer. Remove dead code from the JSC bindings, headers.h, the console builtin, and bun_jsc #40232 and Remove dead code from the inspector protocol package, bun_jsc, bun_install, and the Windows named pipe modules #40557 already carry those hunks, so they were dropped here.decode_hex_code_point, and yaml: apply a node's tag in the parser instead of baking it into the next scanned scalar #38147 moves thematch Enc::KINDblock ofNodeScalar::to_exprinto a newYamlString::to_expr. This PR collapses both matches to theirUtf8arm, so whichever lands second needs a small rebase of those two functions. No other open PR touches the removed lines.Follow-up, not in this PR:
Encodingimpl left,Parser<'i, Enc>can becomeParser<'i>over&[u8]: deleteEncoding,Utf8,EncLitandbyte_literal, and rewrite about 300Enc::sites plus 45 bounds. That is a mechanical single-file change, left for after the open yaml fixes (yaml: keep signed hex/octal as strings, fold CRLF as one break in quoted scalars, preserve merge-key source order #34851, yaml: only a plain or !!merge-tagged<<key is a merge key #38027, yaml: apply a node's tag in the parser instead of baking it into the next scanned scalar #38147, yaml: add the tags option to Bun.YAML.parse and Bun.YAML.tags with !env #39939, yaml: escape unpaired surrogates in stringify and read them back in parse #40042) land, so it does not conflict with all of them at once.StringRangepayloads ofNodeTag::VerbatimandNodeTag::Unknownare never read today, but yaml: add the tags option to Bun.YAML.parse and Bun.YAML.tags with !env #39939 (custom tags) starts reading them, so they stay.pubitems inyaml.rstopub(crate)would letdead_code = "deny"own the file. The cross-crate surface is exactlyYAML,CyclicAliasesandYamlParseError.Left in place on purpose:
src/css/prefixes.rs: 119Featurevariants and theirprefixes_forarms are never constructed, but the file is generated bysrc/css/build-prefixes.jsfrom upstream data.src/bun_core/env_var.rs:JENKINS_URLandnpm_lifecycle_eventhave no Rust caller (both are read by raw string elsewhere). Remove dead code from bun_core, bun_jsc, bun_css, react_compiler, and two C++ bindings #40367 and Remove dead code from bun_jsc, bun_runtime, bun_core, and the JSC bindings #40824 already edit this list.bun_core::strings::split_oncehas no caller but sits next torsplit_once, which Remove dead code from bun_jsc, bun_runtime, bun_core, and the JSC bindings #40824 removes.AsyncLocalStorage.prototype._enable/_propagateandAsyncResource.prototype.emitBefore/emitAfter: Node-compatible surface that user code can call.