### 🚀 Features -8dd67a6transform-react: Expose TypeScript transform options (Tomas Särnhammar) -deed7dcparser: More friendly error for duplicate import attribute key (#28262) (sapphi-red) ### 🐛 Bug Fixes -eaa8e90ecmascript: Avoid numeric `+` folding when an operand may be a string (#28544) (camc314) -b03c7b8regular_expression: Allow incomplete oversized legacy quantifiers (#28449) (Boshen) -128c67dsemantic: Check strict eval and arguments writes by reference flags (#28445) (Boshen) -c97c43cparser: Reject TypeScript default exports in JavaScript (#28440) (Boshen) -fdd119fspan: Count Unicode characters when filtering typo suggestions (#28452) (Boshen) -cb64638regular_expression: Reject incomplete Unicode atom escapes (#28448) (Boshen) -fc0eed3semantic: Stop let-binding scans at arrow functions (#28444) (Boshen) -3421516parser: Preserve default import names in reexports (#28442) (Boshen) -a1e7e5fparser: Reject optional class members in JavaScript (#28439) (Boshen) -5b9a7bcparser: Parse sloppy let expressions and labels (#28438) (Boshen) -8e61652regex: Reject templates without cooked values (#28345) (Boshen) -3b36543parser: Preserve in-context after TypeScript type arguments (#28300) (Boshen) -2e3126cregex: Decode constructor patterns and flags consistently (#28298) (Boshen) -8a90be2regex: Track capture groups and disjunction identity (#28297) (Boshen) -3dc2cb0regex: Preserve escape values and boundaries (#28296) (Boshen) -fc8acbcparser: Handle leading-zero numeric exponents (#28295) (Boshen) -91a638dparser: Normalize raw template line endings with invalid escapes (#28285) (Boshen) -2ac9a42parser: Allow parenthesized private-in expressions (#28284) (Boshen) -052bca9ast: Prevent greyed out fields in AST types in IDEs (#28335) (overlookmotel) -ed7df7dast/estree: Include comments in TS Program span (#28326) (camc314) ### ⚡ Performance -9b6b7bfregular_expression: Advance validated Unicode escapes directly (#28514) (Boshen) -82e1982regular_expression: Share Unicode property name prefixes (#28513) (Boshen) -5395a40regular_expression: Parse class set character prefixes once (#28512) (Boshen) -3708934regular_expression: Defer literal range dash allocation (#28511) (Boshen) -d85ee3dsemantic: Skip arguments ancestry checks outside classes (#28510) (Boshen) -cf81d07semantic: Reuse private reference resolution (#28509) (Boshen) -a79eebcsemantic: Avoid duplicate maps for public JavaScript members (#28508) (Boshen) -235ca3bsemantic: Skip escape checks for unescaped strings (#28507) (Boshen) -babf44cparser: Reuse shorthand assignment target identifiers (#28504) (Boshen) -444f24aecmascript: Short-circuit simple parameter checks for rest (#28503) (Boshen) -04b20c0semantic: Compute duplicate parameter policy once per list (#28446) (Boshen) -dbf8482parser: Use token lookahead for simple function types (#28489) (Boshen) -bca1275parser: Avoid unused destructuring rest capacity (#28499) (Boshen) -691be5cparser: Compact cover initialized name storage (#28495) (Boshen) -b3b5444parser: Build simple arrow bindings directly (#28493) (Boshen) -e1c9bafparser: Disambiguate single-identifier arrow heads (#28491) (Boshen) -550e98aregular_expression: Avoid rescanning unique capture names (#28450) (Boshen) -10e9fc7parser: Skip duplicate lookup for singleton import attributes (#28441) (Boshen) -5238839parser: Use a stack buffer for float separators (#28435) (Boshen) -6e35e3cparser: Fast-path leaf expressions before delimiters (#28432) (Boshen) -3d7512cparser: Decode Unicode identifiers once (#28414) (Boshen) -30f59f4parser: Factor object type opening brace (#28430) (Boshen) -028a267parser: Always inline postfix update parsing (#28429) (Boshen) -1b5a171parser: Reuse export kind classification (#28424) (Boshen) -179a432parser: Factor return type identifier parsing (#28416) (Boshen) -553dd1dparser: Inline hot paths and fold function dispatch (#28404) (Boshen) -de75d56parser: Combine parenthesized arrow lookahead (#28412) (Boshen) -a768a0cparser: Reuse comment annotations after rewind (#28408) (Boshen) -563d92aparser: Skip redundant source cursor updates (#28409) (Boshen) -7941ca9parser: Factor tuple identifier parsing (#28398) (Boshen) -426c151parser: Construct completed tokens without intermediate writes (#28291) (Boshen) -df42953minifier: Don't request another pass for block unwrapping (#28315) (Dunqing) -c2d663dparser: Avoid vectors for single parenthesized expressions (#28374) (Boshen) -50bd0a9parser: Size delimited lists after the first element (#28373) (Boshen) -bd869b5parser: Bypass redundant operand parsing (#28372) (Boshen) -455fc09parser: Skip keyword checks for plain identifier expressions (#28371) (Boshen) -61303fbparser: Fast-path identifier operands (#28306) (Boshen) -6cf5b1aparser: Guard arrow and conditional parsing (#28305) (Boshen) -3666939parser: Specialize identifier reference parsing (#28303) (Boshen) -0d6641aparser: Skip inapplicable expression parsing paths (#28294) (Boshen) -3be7997parser: Reduce lexer search batch size (#28292) (Boshen) -ab5655aregex: Remove redundant character-class and quantifier checks (#28288) (Boshen) -ec8e8d4parser: Remove redundant grammar and lexer checks (#28287) (Boshen) -c903f5cparser: Specialize known-token parsing (#28286) (Boshen) -2683225str: `static_ident!` and `static_str!` macros guarantee const evaluation (#28340) (overlookmotel) -df90836ast: Reduce compile time of `#[ast]` macro (#28336) (overlookmotel) -8239dacparser: Replace dragonbox_ecma with zmij_ecma (#28282) (Boshen)
Oxc's modular runtime helpers
Vendored from the complete published @babel/runtime@8.0.8 package, including all 95 CommonJS/ESM helper pairs and Babel's MIT license. All credits to the Babel team.
upstream.json records the upstream version, SHA-256 of every upstream helper file, and the local patches. The tests check these hashes so unrecorded edits cannot silently diverge from Babel.
Differences from Babel
setFunctionName.jsandesm/setFunctionName.jspreserve"[]"forSymbol(""), matching native computed method names. Babel 8.0.8 returns an empty name. These files are unchanged from Oxc's existing helpers and are the only patches to the upstream helper tree.- Oxc retains its three TypeScript legacy decorator helpers:
decorate,decorateParam, anddecorateMetadata. They are adapted from TypeScript and are absent from Babel 8. - The 26 older Babel helpers removed in Babel 8 remain available for compatibility with previously generated code. Their names are listed in
upstream.json; they are outside the Babel 8 source snapshot. - Package identity, Oxc's version and Node.js requirements, and the
src/layout remain Oxc-specific. Babel's export targets andsideEffects: falseare synchronized while preserving Oxc's existing conditional-export precedence; explicithelpers/esm/*and older package exports remain supported.
Updating
Download and extract a specific published version of @babel/runtime, then run from this directory:
node scripts/sync.mjs /path/to/extracted/babel-runtime
The script copies every unpatched upstream helper and the license, updates exports and the hash manifest, and preserves compatibility helpers and recorded local patches. Before writing, it checks that each patched helper still matches its recorded local hash and that its upstream source is unchanged. If upstream changes a patched helper, the script stops so its local changes can be reviewed against the new version.
The manifest uses the script's generated JSON formatting and is excluded from repository formatting. Repeating the command with the recorded upstream version leaves the runtime tree unchanged. Tests reconstruct that upstream tree offline, using the vendored helpers and the original sources of the two patched helpers.
Run the import, integrity, and runtime behavior tests with:
node --run test