feat(oxlint): add maxWarnings config option

[0xReLogic]

Summary

This PR adds support for the maxWarnings configuration option in .oxlintrc.json files, allowing users to specify a warning threshold that will cause the linter to exit with a non-zero code.

Changes

• Added max_warnings field to Oxlintrc struct in crates/oxc_linter/src/config/oxlintrc.rs
• Wired max_warnings through the config system to DiagnosticService
• CLI --max-warnings flag takes precedence over config file value
• Added validation to prevent maxWarnings in nested config files (raises error as specified)
• Added unit tests for parsing and merging behavior

Example Usage

{
  "maxWarnings": 0
}

Testing

• ✅ All new unit tests pass
• ✅ Existing tests pass (except unrelated tsgolint tests)
• ✅ Config parsing works correctly
• ✅ Merge behavior works as expected
• ✅ Nested config validation works

Closes #15020

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[Copilot]

Pull Request Overview

This PR adds support for configuring a maxWarnings threshold in the .oxlintrc.json configuration file. This allows projects to enforce a maximum number of warnings before the linter exits with an error status, complementing the existing CLI flag --max-warnings.

Key changes:

• Added max_warnings field to the Oxlintrc struct with JSON serialization support
• Updated the merge logic to handle max_warnings configuration inheritance
• Modified the diagnostic service initialization to prioritize CLI flag over config file value
• Added validation to prevent maxWarnings from being used in nested configuration files

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
crates/oxc_linter/src/config/oxlintrc.rs	Adds max_warnings field to the Oxlintrc struct, updates merge logic to handle the new field, and includes comprehensive tests for serialization and merging behavior
apps/oxlint/src/lint.rs	Integrates config-based max_warnings with CLI flag, adds validation to reject maxWarnings in nested configs, and updates diagnostic service initialization to use the merged value

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[camc314]

Thanks for working on this!

Can we add some integration tests for this.

The test cases (real files) should go in apps/oxlint/src/fixtures, and the test fn should go in apps/oxlint/src/lint.rs

[0xReLogic]

Hi @camc314 Already added integration tests as requested. The tests cover:

• maxWarnings: 0 configuration (fails when warnings are present)
• maxWarnings threshold exceeded scenario
• maxWarnings threshold not exceeded scenario
• CLI flag overriding config file value
• Nested config validation (error when maxWarnings is in nested config)

All tests pass and snapshots have been created.