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The BindingIdentifier of a FunctionExpression (and GeneratorExpression)
is parsed with [~Await], and the async arrow head restrictions do not
look into nested functions, so `async (x = function await() {}) => {}`
is valid in scripts. The function name was parsed in the enclosing
expression scope, so the `await` error was recorded on the possible
async arrow head and raised once `=>` was seen. Parse the name in its
own expression scope, like the function's params and body.
Assisted-by: Claude Opus 5.5 <noreply@anthropic.com>
JLHwung
added
PR: Bug Fix 🐛
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Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/62269 |
|
commit: |
| "type": "File", | ||
| "start":0,"end":33,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":33,"index":33}}, | ||
| "errors": [ | ||
| "SyntaxError: Can not use 'await' as identifier inside an async function. (1:17)" |
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Is it intended that this behaves differently?
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Yes, it is intended. ClassExpression inherits [?Await] while FunctionExpression is explicitly parsed with [~Await].
nicolo-ribaudo
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Oct 5, 2026
liuxingbaoyu
approved these changes
Oct 5, 2026
JLHwung
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fix-parser-await-function-name-in-async-arrow-params
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October 5, 2026 18:58
brandhaug
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Oct 10, 2026
## pnpm-workspace.yaml (default) ## Dependency Updates | Package | From | To | Type | | --- | --- | --- | --- | | `@babel/core` | 8.0.6 | 8.0.7 | patch | | `@react-email/ui` | 6.11.0 | 6.11.1 | patch | | `ai` | 7.0.128 | 7.0.130 | patch | | `react-email` | 6.11.0 | 6.11.1 | patch | | `shadcn` | 4.21.3 | 4.21.4 | patch | ## Release Notes <details> <summary><b>@<!---->babel/core</b> (8.0.6 → 8.0.7)</summary> ## v8.0.7 (2026-10-07) Thanks @<!---->brunoborta, @<!---->CINC0S, @<!---->hoobnn, and @<!---->jpradelle for your first PRs! #### 🐛 Bug Fix * `babel-helper-create-regexp-features-plugin`, `babel-plugin-transform-dotall-regex`, `babel-plugin-transform-unicode-sets-regex`, `babel-preset-env` * [#18295](babel/babel#18295) Bump regexpu-core to 6.5.3 ([@<!---->JLHwung](https://github.com/JLHwung)) * `babel-plugin-transform-for-of` * [#18292](babel/babel#18292) Skip `for await` in `transform-for-of` ([@<!---->brunoborta](https://github.com/brunoborta)) * `babel-helpers`, `babel-plugin-transform-async-generator-functions`, `babel-runtime-corejs3` * [#18283](babel/babel#18283) Fix `asyncIterator` helper forwarding `.throw()` to `.return()` ([@<!---->brunoborta](https://github.com/brunoborta)) * `babel-parser` * [#18288](babel/babel#18288) fix(parser): allow await as a function expression name inside async arrow ([@<!---->JLHwung](https://github.com/JLHwung)) * `babel-helpers`, `babel-plugin-transform-class-properties`, `babel-plugin-transform-modules-systemjs`, `babel-runtime-corejs3` * [#18284](babel/babel#18284) Guard `@@toPrimitive` usage in toPrimitive helper ([@<!---->nicolo-ribaudo](https://github.com/nicolo-ribaudo)) * `babel-plugin-transform-block-scoping` * [#18195](babel/babel#18195) fix: closures in for-loop init capture wrong binding ([@<!---->joelle-a-dev](https://github.com/joelle-a-dev)) * `babel-helper-create-class-features-plugin`, `babel-plugin-transform-private-property-in-object` * [#18265](babel/babel#18265) Return false for `#x in` on static private fields before initialization ([@<!---->hoobnn](https://github.com/hoobnn)) * `babel-traverse` * [#18151](babel/babel#18151) Evaluate TypeScript expression wrappers in `NodePath#evaluate` ([@<!---->CINC0S](https://github.com/CINC0S)) * [#18250](https://github …[full notes](https://github.com/babel/babel/releases/tag/v8.0.7) </details> <details> <summary><b>react-email</b> (6.11.0 → 6.11.1)</summary> ### Patch Changes * 54769fc: Prevent `email export` from deleting the project, the home directory, the email templates or the static assets when `--outDir` points at them. * 6926bac: `<Markdown>` now applies `markdownCustomStyles.th` to table header cells. Header cells were previously styled with `td`, so any `th` styles were ignored. </details> <details> <summary><b>shadcn</b> (4.21.3 → 4.21.4)</summary> ### Patch Changes - [#12189](shadcn-ui/ui#12189) [`76fd499595ba7cc01f49d159bd7ac82d7aca8e63`](shadcn-ui/ui@76fd499) Thanks [@<!---->shadcn](https://github.com/shadcn)! - Drop the ts-morph dependency from @<!---->shadcn/registry. - [#12184](shadcn-ui/ui#12184) [`995c2cfff44c373bd210d451089726ec097ab917`](shadcn-ui/ui@995c2cf) Thanks [@<!---->shadcn](https://github.com/shadcn)! - Run the icons and asChild transformers without ts-morph. - [#12160](shadcn-ui/ui#12160) [`6efecd8fe9aa167886fe2cc0c05c5623a5bb5670`](shadcn-ui/ui@6efecd8) Thanks [@<!---->shadcn](https://github.com/shadcn)! - Edit the Next.js layout for font items without ts-morph, and skip it with a warning instead of writing a broken layout. - [#12188](shadcn-ui/ui#12188) [`efa11781f756c86debb0392fbea4fe468250b41b`](shadcn-ui/ui@efa1178) Thanks [@<!---->shadcn](https://github.com/shadcn)! - Rewrite imports and crawl file imports without ts-morph. - [#12177](shadcn-ui/ui#12177) [`e8c3143b1cd191280befcd6c9538284bb43399a8`](shadcn-ui/ui@e8c3143) Thanks [@<!---->shadcn](https://github.com/shadcn)! - Edit tailwind.config without ts-morph, and skip it with a warning instead of writing a broken config. - [#12183](shadcn-ui/ui#12183) [`f56bbd7282f0116a925a601cb6d7e0c3fede448b`](shadcn-ui/ui@f56bbd7) Thanks [@<!---->shadcn](https://github.com/shadcn)! - Run the rsc, import, CSS variable, cleanup, font and menu transformers without ts-morph. - [#12185](shadcn-ui/ui#12185) [`4a90344c42dc9ae47494179065219377ff5f2a8f`](https://github.com/shadcn-ui/u …[full notes](https://github.com/shadcn-ui/ui/releases/tag/shadcn%404.21.4) </details> --- *This PR was auto-generated by [catalog-update-action](https://github.com/brandhaug/catalog-update-action).* Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Collaborator
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Backported to 7.x in #18449. |
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async (x = function await() {}) => {}In this PR we fix a parser bug detected by Claude Opus 5.5: The BindingIdentifier of a FunctionExpression (and GeneratorExpression) is parsed with
[~Await], and the async arrow head do not pass through[Await]to the nested function, soasync (x = function await() {}) => {}is valid in scripts.FF, JSC and V8 all accept this production.