# Biome 2.5.8 — Biome CLI v2.5.8

- Product: Biome (https://whatsnew.fyi/product/biome)
- Vendor: Biome
- Date: 2026-08-11
- Version: 2.5.8
- Original notes: https://github.com/biomejs/biome/releases/tag/%40biomejs/biome%402.5.8
- Permalink: https://whatsnew.fyi/product/biome/releases/2.5.8

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'.

---

- **added** — Add a new nursery rule useReactCompiler which reports diagnostics from React Compiler lint mode
- **changed** — Improve performance of noImportCycles
- **added** — Add the nursery rule noSvelteLegacyConst which disallows legacy Svelte {@const} tags and recommends declaration tags with $derived()
- **fixed** — Fix useAwait to no longer report async functions that contain an await using declaration
- **fixed** — Fix noUselessUndefined to no longer report return undefined when the enclosing function has a return type annotation other than undefined or void
- **fixed** — Fix CSS block comments between a declaration colon and value to preserve their source indentation
- **fixed** — Fix CSS formatting to keep comments inside functional pseudo-classes and pseudo-elements instead of moving them before the function name
- **changed** — Parse HTML style attribute values as CSS and apply all Biome CSS lint rules to style attributes
- **fixed** — Fix Svelte files failing to parse when an expression begins with an object literal
- **fixed** — Fix JavaScript GritQL patterns with multiple metavariables to match snippets consistently in WebAssembly
- **added** — Add the nursery rule noInvalidPropertyInitValue which reports an @property whose initial-value does not match its syntax descriptor
- **changed** — Improve the diagnostic emitted by noRootType
- **changed** — Improve the performance of noMisusedPromises when analyzing async class methods that call other methods through this

##### 2.5.8

###### Patch Changes

- [#10710](https://github.com/biomejs/biome/pull/10710) [`0a0fbc1`](https://github.com/biomejs/biome/commit/0a0fbc15d67c410c80dfae398903f845544fcd65) Thanks [@dyc3](https://github.com/dyc3)! - Added a new nursery rule [`useReactCompiler`](https://biomejs.dev/linter/rules/use-react-compiler/), which reports diagnostics from React Compiler lint mode.

- [#11251](https://github.com/biomejs/biome/pull/11251) [`ea9dd8a`](https://github.com/biomejs/biome/commit/ea9dd8a93e65f849840415e8e26cd668aa1af913) Thanks [@dyc3](https://github.com/dyc3)! - Improved performance of [`noImportCycles`](https://biomejs.dev/linter/rules/no-import-cycles/).

- [#11247](https://github.com/biomejs/biome/pull/11247) [`52b44d6`](https://github.com/biomejs/biome/commit/52b44d6795741d051bf703bd69c6cb447af8fd1d) Thanks [@dyc3](https://github.com/dyc3)! - Added the nursery rule [`noSvelteLegacyConst`](https://biomejs.dev/linter/rules/no-svelte-legacy-const/), which disallows legacy Svelte `{@const}` tags and recommends declaration tags with `$derived()`.

  Invalid:

  ```svelte
  {#each boxes as box}
    {@const area = box.width * box.height}
    <p>{area}</p>
  {/each}
  ```

  Valid:

  ```svelte
  {#each boxes as box}
    {const area = $derived(box.width * box.height)}
    <p>{area}</p>
  {/each}
  ```

- [#11252](https://github.com/biomejs/biome/pull/11252) [`d5f5704`](https://github.com/biomejs/biome/commit/d5f570414fdcdddf62372e35c05f6dababad9287) Thanks [@Turtle-Hwan](https://github.com/Turtle-Hwan)! - Fixed [#11250](https://github.com/biomejs/biome/issues/11250): [`useAwait`](https://biomejs.dev/linter/rules/use-await/) no longer reports async functions that contain an `await using` declaration.

- [#11143](https://github.com/biomejs/biome/pull/11143) [`6be7be1`](https://github.com/biomejs/biome/commit/6be7be1b147d7b4352ff5625a78bd54a48958950) Thanks [@vznh](https://github.com/vznh)! - Fixed [#11017](https://github.com/biomejs/biome/issues/11017): [`noUselessUndefined`](https://biomejs.dev/linter/rules/no-useless-undefined/) no longer reports `return undefined` when the enclosing function has a return type annotation other than `undefined` or `void`.

- [#11234](https://github.com/biomejs/biome/pull/11234) [`caefe39`](https://github.com/biomejs/biome/commit/caefe393c66340914c481f7ccfc82979cf76b61b) Thanks [@subotac](https://github.com/subotac)! - Fixed [#11228](https://github.com/biomejs/biome/issues/11228): CSS block comments between a declaration colon and value now preserve their source indentation.

  ```diff
   :root {
     --font-stack:
  -/* comment */
  +    /* comment */
       system-ui;
   }
  ```

- [#11285](https://github.com/biomejs/biome/pull/11285) [`bca1f73`](https://github.com/biomejs/biome/commit/bca1f73d939423056337bfd0a42cbdcb66bb1e3f) Thanks [@denbezrukov](https://github.com/denbezrukov)! - Fixed [#11280](https://github.com/biomejs/biome/issues/11280): CSS formatting keeps comments inside functional pseudo-classes and pseudo-elements instead of moving them before the function name.

  ```diff
  -:/* comment */ where(div) {}
  +:where(/* comment */ div) {}
  ```

- [#11080](https://github.com/biomejs/biome/pull/11080) [`af16a0b`](https://github.com/biomejs/biome/commit/af16a0bf884c48bad2caab70e7930096e81e1c99) Thanks [@dyc3](https://github.com/dyc3)! - HTML `style` attribute values are now parsed as CSS. All Biome CSS lint rules are applied to the `style` attributes.

- [#11195](https://github.com/biomejs/biome/pull/11195) [`6a85588`](https://github.com/biomejs/biome/commit/6a85588578725195625281984a47c9a8563bf103) Thanks [@dyc3](https://github.com/dyc3)! - Fixed Svelte files failing to parse when an expression begins with an object literal.

  Now the following snippet is correctly parsed:

  ```svelte
  <p>{{ a: true }}</p>
  <div class={{ active: isActive }}></div>
  ```

- [#11173](https://github.com/biomejs/biome/pull/11173) [`481d008`](https://github.com/biomejs/biome/commit/481d008f6e8872

_[Truncated at 4000 characters — full notes: https://github.com/biomejs/biome/releases/tag/%40biomejs/biome%402.5.8]_