fix: Support experimental.async compiler option

[baseballyama]

close: #1434

[changeset-bot]

🦋 Changeset detected

Latest commit: a4f290b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
eslint-plugin-svelte	Patch

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Pull request overview

This PR adds support for the experimental.async compiler option in Svelte 5, which allows top-level await in Svelte components. The fix ensures that when this option is configured in the eslint parser's svelteConfig, it's properly passed to the Svelte compiler during validation.

• Extracts and passes the experimental.async compiler option from parser configuration to the Svelte compiler
• Adds comprehensive test coverage for both valid (option enabled) and invalid (option disabled) scenarios
• Follows existing patterns for selectively passing compiler options

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/eslint-plugin-svelte/src/shared/svelte-compile-warns/index.ts	Extracts experimental.async from svelteConfig and passes it to compiler.compile()
packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/valid/svelte-config-experimental-async/_config.cjs	Test configuration enabling experimental.async option
packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/valid/svelte-config-experimental-async/top-level-await-input.svelte	Valid test case with top-level await when option is enabled
packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/valid/svelte-config-experimental-async/top-level-await-requirements.json	Specifies Svelte 5.0.0+ requirement for valid test
packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/experimental-async-disabled/top-level-await-input.svelte	Invalid test case with top-level await when option is disabled
packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/experimental-async-disabled/top-level-await-errors.yaml	Expected error output for invalid test case
packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/experimental-async-disabled/top-level-await-requirements.json	Specifies Svelte 5.0.0+ requirement for invalid test
.changeset/wild-steaks-invent.md	Changeset entry documenting this fix as a patch release

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[ota-meshi]

Thanks!