fix: Unity 6.5 projects compile without metadata type conflicts

[hatayama]

Fixes #1370

Summary

• Unity 6.5 projects can compile Unity CLI Loop without duplicate metadata type errors.
• Older Unity versions keep using the bundled metadata validation dependencies.

User Impact

• Before this change, Unity CLI Loop 2.1.8 and 2.1.9 failed to compile on Unity 6000.5 with CS0433 errors from metadata validation code.
• Unity 6000.5 now uses Unity-provided metadata assemblies while earlier supported Editors keep the bundled dependencies.

Changes

• Exclude bundled metadata validation dependency plugins from Unity 6000.5 and newer with Unity define constraints.
• Keep the explicit-reference importer setting that prevents accidental implicit references.
• Add package metadata coverage for the Unity 6000.5 exclusion.

Verification

• uloop compile --force-recompile true --wait-for-domain-reload true
• npm --prefix Packages/src/Cli~ run test:cli -- --runTestsByPath src/__tests__/package-metadata.test.ts
• npm --prefix Packages/src/Cli~ run lint
• npm --prefix Packages/src/Cli~ run build
• codex review --commit HEAD

Summary

This PR fixes compilation failures in Unity CLI Loop when building with Unity 6.5 (version 6000.5 and newer) that were present in versions 2.1.8 and 2.1.9.

Problem

The bundled metadata validation dependency packages caused CS0433 errors (duplicate metadata type conflicts) when compiling with Unity 6000.5 and newer, which now includes its own System.Reflection.Metadata reference during editor compilation.

Solution

The fix excludes bundled metadata validation dependencies from Unity 6000.5+ through Unity define constraints, while maintaining explicit-reference importer settings for older Unity versions to prevent accidental implicit references. Package metadata coverage is added to document and enforce the exclusion.

Changes

Packages/src/Cli~/src/tests/package-metadata.test.ts

• Added constant METADATA_VALIDATION_DEPENDENCY_DEFINE_CONSTRAINT = '!UNITY_6000_5_OR_NEWER'
• Introduced new test case: "excludes bundled metadata validation dependencies from Unity 6000.5 and newer"
• Test validates that each metadata validation dependency .meta file (System.Collections.Immutable, System.Reflection.Metadata, and System.Runtime.CompilerServices.Unsafe) contains the !UNITY_6000_5_OR_NEWER define constraint

The test verifies the define constraint is properly configured in the three bundled dependency .meta files to ensure they are excluded when compiling with Unity 6000.5 and newer versions.

Verification

The fix has been verified through:

• Compilation with force-recompile and domain-reload options
• Package metadata tests
• Linting and building
• Code review

[coderabbitai]

📝 Walkthrough

Walkthrough

A new constant METADATA_VALIDATION_DEPENDENCY_DEFINE_CONSTRAINT (!UNITY_6000_5_OR_NEWER) is added to the package metadata test file. A new Jest test iterates over METADATA_VALIDATION_DEPENDENCY_META_PATHS and asserts each .meta file contains an exclusion entry referencing that constraint.

Changes

Metadata validation dependency define constraint test

Layer / File(s)	Summary
Define constraint constant and .meta exclusion test Packages/src/Cli~/src/__tests__/package-metadata.test.ts	Adds METADATA_VALIDATION_DEPENDENCY_DEFINE_CONSTRAINT = '!UNITY_6000_5_OR_NEWER' and a test that loads each metadata validation dependency .meta file and verifies it contains the string - '<!UNITY_6000_5_OR_NEWER>'.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related issues

• Unity 6000.5: CS0433 metadata type conflicts with 2.1.8 and 2.1.9 #1370: This PR adds a test specifically verifying the !UNITY_6000_5_OR_NEWER exclusion constraint in bundled metadata validation dependency .meta files, directly validating the fix for the CS0433 type conflict described in that issue.

Possibly related PRs

• hatayama/unity-cli-loop#1288: Both PRs modify the same test file (package-metadata.test.ts) to validate bundled metadata validation dependency .meta file contents using METADATA_VALIDATION_DEPENDENCY_META_PATHS, with the current PR extending those checks to cover the !UNITY_6000_5_OR_NEWER define constraint.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title mentions 'Unity 6.5 projects compile without metadata type conflicts,' which aligns with the PR objective of fixing compilation failures in Unity 6.5. However, the actual changeset only adds a test case and a constant for Unity 6000.5 exclusion; it doesn't show the complete implementation of the fix (the actual meta file modifications are in ignored files). The title partially reflects the main change but oversimplifies the scope.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/issue-1370

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[cubic-dev-ai]

No issues found across 4 files

_{Re-trigger cubic}