# Oxc crates_v0.139.0 — oxc crates_v0.139.0

- Product: Oxc (https://whatsnew.fyi/product/oxc)
- Vendor: Oxc
- Date: 2026-07-06
- Version: crates_v0.139.0
- Original notes: https://github.com/oxc-project/oxc/releases/tag/crates_v0.139.0
- Permalink: https://whatsnew.fyi/product/oxc/releases/crates-v0.139.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — Include unresolved references in semantic examples
- **added** — Fold boolean-literal ternary branches in value contexts in minifier
- **added** — Implement `ReplaceWith` on all AST types
- **added** — Add `ReplaceWith` trait to allocator
- **added** — Add `reserved` option for names that must not be mangled in mangler
- **added** — Add `StringExt` trait to data_structures
- **added** — Drop side-effect-free IIFEs whose result is unused in minifier
- **added** — Add method to widen inherited enum ref to parent ref in AST
- **fixed** — Preserve decorated class read bindings in transformer
- **fixed** — Declare temp for renamed anonymous class in transformer
- **fixed** — Scope anonymous decorated class bindings correctly in transformer
- **fixed** — Preserve namespace strict mode flags in transformer
- **fixed** — Correct scoping flags for lowered enums in transformer
- **fixed** — Clean up semantics for stripped TypeScript syntax in transformer
- **fixed** — Compile generic functions instead of over-bailing on type-param hoisting in react_compiler
- **fixed** — Align memoization cache-slot allocation with Babel in react_compiler
- **fixed** — Drop stray empty statement from catch bindings in react_compiler
- **fixed** — Codegen destructuring reassignment targets in react_compiler
- **fixed** — Preserve direct eval scope flags in transformer async-to-generator
- **fixed** — Keep names of destructured exported bindings in mangler

###### 🚀 Features

- 260425f semantic/examples: Include unresolved references (#24214) (camc314)
- 2d9b0b3 minifier: Fold boolean-literal ternary branches in value contexts (#24110) (Dunqing)
- 61fbf10 ast: Implement `ReplaceWith` on all AST types (#24013) (overlookmotel)
- 7db7a29 allocator: Add `ReplaceWith` trait (#24012) (overlookmotel)
- 4eb074e mangler: Add `reserved` option for names that must not be mangled (#24041) (Dunqing)
- 2e62012 data_structures: Add `StringExt` trait (#24006) (overlookmotel)
- 60e7160 minifier: Drop side-effect-free IIFEs whose result is unused (#23967) (Dunqing)
- 26dd9e2 ast: Add method to widen inherited enum ref to parent ref (#23961) (overlookmotel)

###### 🐛 Bug Fixes

- df62046 transformer: Preserve decorated class read bindings (#24231) (camc314)
- ce5f40f transformer: Declare temp for renamed anonymous class (#24230) (camc314)
- 09bd638 transformer: Scope anonymous decorated class bindings correctly (#24229) (camc314)
- 4b7fa9c transformer: Preserve namespace strict mode flags (#24227) (camc314)
- d8ead84 transformer: Correct scoping flags for lowered enums (#24225) (camc314)
- e8b50ee transformer: Clean up semantics for stripped TypeScript syntax (#24180) (camc314)
- d966d0b react_compiler: Remove clippy allows (#24168) (Boshen)
- 854ef8d react_compiler: Compile generic functions instead of over-bailing on type-param hoisting (#24158) (Boshen)
- 093586c react_compiler: Align memoization cache-slot allocation with Babel (#24157) (Boshen)
- 09c8f59 react_compiler: Normalize snapshot fixture paths (#24142) (camc314)
- f13df97 react_compiler: Drop stray empty statement from catch bindings (#24133) (Boshen)
- cb2a505 react_compiler: Codegen destructuring reassignment targets (#24131) (Boshen)
- b82c394 react_compiler: Propagate codegen invariants instead of emitting empty bodies (#24128) (Boshen)
- 5771982 react_compiler: Render unchanged programs as source in fixture snapshots (#24129) (Boshen)
- 4b16e1a transformer/async-to-generator: Preserve direct eval scope flags (#24136) (camc314)
- 4e9194f react_compiler: Lower `delete obj.prop` to Property/ComputedDelete (#24123) (Boshen)
- 0b25582 ast: Type binding node `typeAnnotation` as `TSTypeAnnotation | null` (#23113) (Boshen)
- 018c0e5 transformer: Hoist lowered async declarations (#22770) (camc314)
- 652fbaf mangler: Keep names of destructured exported bindings (#24036) (Dunqing)
- e274415 minifier: Don't drop global calls that throw despite pure arguments (#23917) (Dunqing)
- 59abb30 minifier: Only merge string literals in `try_fold_add` when the inner operator is `+` (#23622) (Jerry Zhao)

###### ⚡ Performance

- c5ca77b transformer: Avoid cloning refresh options (#24191) (camc314)
- bf1a151 react_compiler: Compile out debug printers (#24184) (Boshen)
- abb44a0 transformer: Build fixed object-rest arguments (#24190) (camc314)
- a4db731 isolated_declarations: Use `ReplaceWith` instead of `TakeIn` (#24016) (overlookmotel)
- ff10855 transformer: Use `ReplaceWith` instead of `TakeIn` (#24015) (overlookmotel)
- bd49aff ecmascript: Avoid heap-allocating Math.min/max/imul operands (#23941) (Lawrence Lin)
- e4b708b react_compiler: Skip compiled files before prefilters (#24171) (Boshen)
- c59f2fe rust: Return impl ExactSizeIterator from slice-backed accessors (#24144) (Boshen)
- 5d6d04a codegen: SWAR-skip boring byte runs in sourcemap line/column scan (#24023) (Boshen)
- a55e0be traverse: Reduce string operations in `get_var_name_from_node` (#24007) (overlookmotel)
- e6d48e1 transformer/nullish_coalescing: Move cold path into separate function (#23989) (overlookmotel)
- c4e35b5 transformer/object_rest_spread: Pre-allocate capacity in `Vec` (#23988) (overlookmotel)
- 527b8e5 transformer/decorators: Narrow type earlier (#23987) (overlookmotel)

###### 📚 Documentation

- 1589f54 semantic: Update docs for `Scoping::set_symbol_name` (#24223) (camc314)
- 30d17f5 allocator: Clarify docs for `TakeIn::take_in_box` (#24093) (overlookmotel)
- 675e6a8 ast

_[Truncated at 4000 characters — full notes: https://github.com/oxc-project/oxc/releases/tag/crates_v0.139.0]_