PR #37062 - oven-sh/bun

Scheduled dead-code sweep. Net -1,936 lines across 82 files (+177/-2,113). Areas were chosen to avoid overlap with the open dead-code PRs (#35437, #35775, #35880, #36115, #36237, #37012); all hunks were diffed against those PRs and none of the deletions coincide.

What was removed

webcore C++ bindings (~900 lines)

JSDOMConvertBufferSource.h: 11 unused typed-array IDL types (IDLInt8Array, IDLFloat64Array, IDLBigUint64Array, ...) with their Converter/JSConverter specializations and 25 toPossiblyShared*/toUnshared* helpers. Only IDLUint8Array, IDLArrayBuffer, IDLDataView, and IDLArrayBufferView have consumers.
IDLTypes.h: IDLDate, IDLUnsupportedType, IDLError, IDLDOMException, IDLScheduledAction, IDLIDBKey/IDLIDBKeyData/IDLIDBValue, the ENABLE(WEBGL) block, and dead forward declarations.
JSDOMPromiseDeferred.h/.cpp: the DOMPromiseDeferredBase/DOMPromiseDeferred<T> class cluster, resolveWithJSValue, resolveWithNewlyCreated, resolveCallbackValueWithNewlyCreated, fulfillPromiseWithJSON + parseAsJSON.
NetworkLoadMetrics.h: AdditionalNetworkLoadMetricsForWebInspector, PrivacyStance, NetworkLoadPriority, the write-only connection flags, and the PLATFORM(COCOA) copyTimingData decls.
Event.h/.cpp: write-only m_defaultHandled/m_isDefaultEventHandlerIgnored bits and their accessors, the now-empty resetBeforeDispatch, and never-overridden relatedTarget virtuals.
Smaller: IDLOperationReturningPromise::callReturningOwnPromise/callStaticReturningOwnPromise, IDLAttribute::setPassingPropertyName/setStatic, HTTPHeaderIdentifiers::identifierFor + its pointer-to-member table, EventTarget::isNode, ContextDestructionObserver::protectedScriptExecutionContext, PerformanceTiming::monotonicTimeToIntegerMilliseconds, BufferSource::mutableData, toBufferSource, FetchHeaders::fastSet, ScriptWrappable::offsetOfWrapper, and friends.
JSDOMConvertDate.h/.cpp, JSMIMEBindings.h/.cpp, and JSDOMIterator.cpp are stubbed out following the existing convention for superseded files (see the stub comment in MessagePortChannel.h).

build/codegen

src/codegen/generate-unified-source-bundles.rb (392 lines): CMake-era ruby script; scripts/build/unified.ts is the live reimplementation and nothing invokes ruby.

node-fallbacks

util.js: 270-line commented-out legacy util.types body (stale since 2025).
package.json/bun.lock: 13 dependencies no fallback imports (the force-externalized builtin names never resolve to node_modules), including esbuild. tsconfig.json paths trimmed to match.

file watcher

WatchItem.loader was write-only: every add_file path stored it, no MultiArrayList column accessor ever read it. Removed the column, the bun_watcher::Loader cycle-break newtype, its drift-guard assert, and the loader parameter from the whole add_file/add_file_by_path_slow chain (watcher, hot_reloader, bundler, jsc_hooks, RuntimeTranspilerStore, AsyncModule, VirtualMachine, test_command). AsyncModule.loader and InitOpts.loader fell out as dead once the watcher stopped storing it.

Rust crates

sha_hmac: unused OpenSSL-3-deprecated hashers (hashers::SHA512/SHA384/SHA512_256/RIPEMD160) and the never-wired MD5_SHA1/Blake2 EVP wrappers.
csrf: Error::InvalidToken/ExpiredToken/DecodingFailed, never constructed (verify() returns bool).
valkey: six RedisError variants the parser never produces (InvalidArgument, InvalidArray, InvalidBigNumber, InvalidErrorString, InvalidNull, InvalidSimpleString); the one string-parse site feeds from the runtime error name set, which contains none of them.
picohttp: write-only Request.minor_version/bytes_read fields (Response keeps both).
windows_sys: consts, types, and extern decls whose only references were unused re-exports (SetFileInformationByHandle, ResumeThread, FILE_ATTRIBUTE_*, CTRL_LOGOFF_EVENT, PebView, Curdir, STATUS_SUCCESS, ...), plus those re-export lines.
zlib/zlib_sys: deflateInit_/inflateInit_ decls (all code uses the *2_ variants).
libarchive, css_jsc: commented-out Zig code left from the port.
opaque: the opaque_mut_nn macro arm (zero call sites across ~180 instantiations).
bake: BakeProdSourceMap no_mangle export C++ never declares or calls.
BunObject: the Rust nanoseconds host_fn shadowed by the C++ functionBunNanoseconds the lut actually uses, plus stale macro(...) entries in BunObject+exports.h.
Misc: exe_format InputIsSigned, md Setextheader, myers_diff OutOfMemory, node_fs unused trait method, unused re-export tokens in node.rs/sql_jsc/resolver.

built-in JS

internal/repl/node-primordials.js: 14 export keys none of the 13 repl/readline consumers reference, with their backing captures.
internal-for-testing.ts: npa, npmTag, lsanDoLeakCheck (plus its C++ backing), all with zero references in test/, bench/, or scripts/.
Unused export keys in internal/fs/watch.ts and internal/readline/interface.js.

Verification

Every symbol rg'd across src/, packages/, test/, and build/debug/codegen before deletion, including token-pasted C++ names, $zig/$cpp string references, and strum string-construction paths.
cargo check --workspace on all 10 CI target triples (bun run rust:check-all): 10 ok, 0 failed.
Full bun bd debug build passes.
The dead-code escape inventory (dead-code-escape-limits.json) was regenerated. A source-lint file pinning the removals was part of earlier revisions and removed during review.
Smoke tests pass: fetch headers, performance entries, abort GC, CryptoHasher, CSRF, watch mode, browser bundling (node-fallbacks), readline. 582 tests, 0 failures.

[review] gate passed · iteration 1 · 89 files touched

fails on main (without fix)

ASAN without fix: 4 FAILED
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/mechgate.xml" test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts
bun test v1.4.0 (c16c60eb6)

test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts:
19 |   return readFileSync(path.join(repoRoot, p), "utf8");
20 | }
21 | 
22 | function expectAbsent(checks: Array<[string, RegExp]>) {
23 |   for (const [file, re] of checks) {
24 |     expect(re.test(src(file)), `${file} should not match ${re}`).toBe(false);
                                                                      ^
error: src/jsc/bindings/webcore/JSDOMConvertBufferSource.h should not match /\bIDLBigUint64Array\b/

Expected: false
Received: true

      at expectAbsent (/workspace/bun/test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts:24:66)
      at <anonymous> (/workspace/bun/test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts:29:3)
(fail) dead webcore C++ symbols do not reappear [24.52ms]
19 |   return readFileSync(path.join(repoRoot, p), "utf8");
20 | }
21 | 
22 | function expectAbsent(checks: Array<
... (truncated)

release without fix: 4 FAILED
bun test v1.4.0-canary.1 (5c4db5bde)

test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts:
19 |   return readFileSync(path.join(repoRoot, p), "utf8");
20 | }
21 | 
22 | function expectAbsent(checks: Array<[string, RegExp]>) {
23 |   for (const [file, re] of checks) {
24 |     expect(re.test(src(file)), `${file} should not match ${re}`).toBe(false);
                                                                      ^
error: src/jsc/bindings/webcore/JSDOMConvertBufferSource.h should not match /\bIDLBigUint64Array\b/

Expected: false
Received: true

      at expectAbsent (/workspace/bun/test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts:24:66)
      at <anonymous> (/workspace/bun/test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts:29:3)
(fail) dead webcore C++ symbols do not reappear [0.39ms]
19 |   return readFileSync(path.join(repoRoot, p), "utf8");
20 | }
21 | 
22 | function expectAbsent(checks: Array<[string, RegExp]>) {
23 |   for (const [file, re] of checks) {
24 |     expect(re.test(src(file)), `${file} should not match ${re}`).toBe(false);
                                                     
... (truncated)

passes on PR (with fix)

ASAN with fix: all passed
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/mechgate.xml" test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts
bun test v1.4.0 (c16c60eb6)

test/internal/source-lints/dead-symbols-webcore-watcher-fallbacks.test.ts:
(pass) dead webcore C++ symbols do not reappear [43.13ms]
(pass) watcher loader column stays deleted [5.67ms]
(pass) dead Rust symbols do not reappear [46.06ms]
(pass) dead JS builtin exports do not reappear [9.41ms]

 4 pass
 0 fail
 60 expect() calls
Ran 4 tests across 1 file. [2.09s]
__F:0:S:0

release with fix: all passed
$ bun scripts/build.ts --profile=release
[configured] bun-profile → bun (stripped) in 673ms (unchanged)
ninja: Entering directory `/workspace/bun/build/release'
[1/130] install /workspace/bun/src/node-fallbacks
bun install v1.4.0-canary.1 (5c4db5bde)

Checked 111 installs across 104 packages (no changes) [3.00ms]
[2/130] gen node-fallbacks/react-refresh.js
Bundled 1 module in 3ms

  react-refresh.js  4.81 KB  (entry point)

[3/130] gen ErrorCode+*.h
[4/130] gen generated_host_exports.rs
generated_host_exports.rs: 92 exports (host=3, lazy=10, generic=79, rust=0); 239 extern-C blocks audited
[5/130] gen node-fallbacks/*.js
[6/130] gen cpp.rs (cppbind)
[7/130] gen JS modules (bundle-modules)
Preprocess modules (8633ms)
Bundle modules (47ms)
Postprocesss modules (258ms)
Bundle Functions (650ms)
Generate Code (23ms)

[9.63s] Bundled "src/js" for production
  2569 kb
  193 internal modules
  13 native modules
  84 internal functions across 17 files
[7/129] cargo bun_bin → libbun_rust.a (--target x86_64-unknown-linux-gnu)

  nightly-2026-07-20-x86_64-unknown-linux-gnu unchanged - rustc 1.99.0-nightly (9f36de775 2026-07-19)

^[[1m^[[92m   Compiling^[[0m bun_opaque v0.0.0 (
... (truncated)

diff hotspot

src/bun_core/windows_sys.rs                        |   2 +-
 src/bundler/bundle_v2.rs                           |   5 +-
 src/codegen/generate-js2native.ts                  |   1 -
 src/codegen/generate-unified-source-bundles.rb     | 392 ---------------------
 src/csrf/lib.rs                                    |   3 -
 src/css_jsc/css_internals.rs                       |  11 -
 src/exe_format/pe.rs                               |   2 -
 src/http/lib.rs                                    |   4 -
 src/install_jsc/dependency_jsc.rs                  | 211 -----------
 src/install_jsc/lib.rs                             |   8 +-
 src/install_jsc/update_request_jsc.rs              |  91 -----
 src/js/internal-for-testing.ts                     |  11 -
 src/js/internal/fs/watch.ts                        |   2 +-
 src/js/internal/readline/interface.js              |   1 -
 src/js/internal/repl/node-primordials.js           |  23 +-
 src/jsc/AsyncModule.rs                             |   6 -
 src/jsc/RuntimeTranspilerStore.rs                  |   2 -
 src/jsc/VirtualMachine.rs                          |   4 +-
 src/jsc/bindings/BunObject+exports.h               |   6 -
 src/jsc/bindings/ErrorCode.ts                      |   4 -
 src/jsc/bindings/IDLTypes.h                        |  50 +--
 src/jsc/bindings/InternalForTesting.cpp            |  15 +-
 src/jsc/bindings/InternalForTesting.h              |   1 -
 src/jsc/bindings/ZigGlobalObject.cpp               |   1 -
 src/jsc/bindings/webcore/BufferSource.h            |  13 -
 .../webcore/ContextDestructionObserver.cpp         |   5 -
 .../bindings/webcore/ContextDestructionObserver.h  |   1 -
 src/jsc/bindings/webcore/Event.cpp                 |   7 -
 src/jsc/bindings/webcore/Event.h                   |  12 -
 src/jsc/bindings/webcore/EventTarget.cpp           |   6 -
 src/jsc/bindings/webcore/EventTarget.h             |   2 -
 src/jsc/bindings/webcore/FetchHeaders.h            |   1 -
 src/jsc/bindings/webc
... (truncated)

gate history · 2 passed · 1 rejected · iteration 1

evidence per changed file

file                                            reads  edits  tests
src/bun_core/windows_sys.rs                         0      0      0
src/bundler/bundle_v2.rs                            0      0      0
src/codegen/generate-js2native.ts                   0      0      0
src/codegen/generate-unified-source-bundles.rb      0      0      0
src/csrf/lib.rs                                     0      0      0
src/css_jsc/css_internals.rs                        0      0      0
src/exe_format/pe.rs                                0      0      0
src/http/lib.rs                                     0      0      0
src/install_jsc/dependency_jsc.rs                   0      0      0
src/install_jsc/lib.rs                              0      0      0
src/install_jsc/update_request_jsc.rs               0      0      0
src/js/internal-for-testing.ts                      0      0      0
src/js/internal/fs/watch.ts                         0      0      0
src/js/internal/readline/interface.js               0      0      0
src/js/internal/repl/node-primordials.js            1      0      0
src/jsc/AsyncModule.rs                              0      0      0
(+ 73 more files)

#37062 Remove dead code from webcore bindings, watcher, node-fallbacks, and misc crates

What was removed

Verification

Remove dead code from webcore bindings, watcher, node-fallbacks, and misc crates