[TARGET] Fix round-trip reconstruction of targets with canonicalizer-generated feature.* attrs

[mshr-h]

Fix #18882

TargetNode::ToConfig() exports all target attrs, including derived feature.* fields set by target canonicalizers. However, TargetInternal::FromConfig() rejects these keys during schema validation because they are not declared in the target kind schema. This breaks round-tripping exported configs through Target(config).

This PR strips feature.* keys from the config before ConfigSchema::Resolve, then merges them back afterward. Canonicalizer output is authoritative — if the canonicalizer re-emits a feature.* key, it overwrites the preserved value. Unknown non-feature.* keys continue to fail validation as before.

Changes:

• src/target/target.cc: Extract and re-merge feature.* keys around schema resolution in FromConfig()
• tests/cpp/target_test.cc: Add tests for single-target round-trip, nested-host round-trip, and continued rejection of unknown non-feature keys

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical bug preventing the reliable serialization and deserialization of target configurations that include dynamically generated feature.* attributes. By carefully managing these attributes during the configuration parsing process, it ensures that targets can be exported and reconstructed without data loss or validation errors, thereby improving the robustness of target management.

Highlights

• Fix for Target Round-Trip Reconstruction: Resolved an issue where TargetNode::ToConfig() exported canonicalizer-generated feature.* attributes, but TargetInternal::FromConfig() rejected them during schema validation, preventing successful round-trip reconstruction of targets.
• Handling of feature.* Attributes: Implemented a mechanism in TargetInternal::FromConfig() to temporarily strip feature.* keys from the configuration before schema resolution and then merge them back afterward. This ensures these canonicalizer-owned metadata fields are preserved.
• Canonicalizer Output Priority: The fix prioritizes the canonicalizer's output for feature.* keys; if the canonicalizer re-emits a feature.* key, it overwrites any preserved value, maintaining the canonicalizer's authority.
• Validation of Unknown Keys: Confirmed that unknown keys not prefixed with feature.* will continue to cause validation failures, upholding strict schema validation for non-canonicalizer-generated attributes.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Changelog

• src/target/target.cc
  • Modified TargetInternal::FromConfig() to extract feature.* keys before schema resolution and re-merge them afterward, giving priority to canonicalizer output.
  • Updated step numbering in comments to reflect the new logic.
• tests/cpp/target_test.cc
  • Added RoundTripCanonicalizerFeatures test to verify single-target round-trip preservation of feature.* attributes.
  • Added RoundTripCanonicalizerFeaturesNestedHost test to ensure feature.* attributes are preserved in nested host targets during round-trip.
  • Added UnknownNonFeatureKeyStillFails test to confirm that unknown non-feature.* keys continue to fail schema validation as expected.

Activity

• This pull request was opened by mshr-h to fix issue [Bug] Target(config) rejects canonicalizer-generated feature.* attrs exported by Target::ToConfig() #18882.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request fixes an issue with round-trip reconstruction of targets that have feature.* attributes generated by canonicalizers. The approach of temporarily removing these attributes before schema validation and adding them back afterward is sound. The new tests are comprehensive, covering the main functionality, a nested host scenario, and a negative case. I have a couple of suggestions to improve code efficiency and test readability.