Fix generic interface method dispatch for multi-argument types

[josesimoes]

Description

• Loop variable reuse destroyed GenParamCount; KeyValuePair<TKey,TValue> only drained first arg, desynchronized parsers

Motivation and Context

• Fixes explicit interface impl resolution for Dictionary<TKey,TValue> (Remove, Contains, GetEnumerator)
• Generic VAR↔GENERICINST signature matching was dropping arguments when draining nested generic instances
• Drain sub-tree by converging Available() instead of counting arguments by hand
• Surfaced from Sys.Collections unit tests failing.
• Related with Support for generics <T> Home#782.

How Has This Been Tested?

• [tested against Merge generics support in mscorlib CoreLibrary#245].

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue with code or algorithm)
• New feature (non-breaking change which adds functionality to code)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dev Containers (changes related with Dev Containers, has no impact on code or features)
• Dependencies/declarations (update dependencies or assembly declarations and changes associated, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist

• My code follows the code style of this project (only if there are changes in source code).
• My changes require an update to the documentation (there are changes that require the docs website to be updated).
• I have updated the documentation accordingly (the changes require an update on the docs in this repo).
• I have read the CONTRIBUTING document.
• I have tested everything locally and all new and existing tests passed (only if there are changes in source code).

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository YAML (base), Central YAML (inherited)

Review profile: ASSERTIVE

Plan: Pro

Run ID: 52d0de23-29f7-48ed-8328-e4d866de0df5

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

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.}

[josesimoes]

@coderabbitai review

[coderabbitai]

✅ Action performed

Review finished.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.

[coderabbitai]

Caution

Failed to replace (edit) comment. This is likely due to insufficient permissions or the comment being deleted.

Error details

{}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/CLR/Core/TypeSystem.cpp`:
- Around line 9119-9147: Refactor the duplicated drain logic in
MatchSignatureForVirtualDispatch by extracting the repeated parser.Advance loop
into a small helper such as DrainGenericInstSubtree. Both
DATATYPE_VAR/DATATYPE_GENERICINST branches should call the helper with the
appropriate CLR_RT_SignatureParser instance and targetAvail value, then continue
on success or return false on failure. Keep the helper near TypeSystem.cpp so
the two branches in MatchSignatureForVirtualDispatch are flattened and the
nesting/duplication is removed.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Central YAML (inherited)

Review profile: ASSERTIVE

Plan: Pro

Run ID: d69393eb-6e41-445b-8d74-feddbfc49951

📥 Commits

Reviewing files that changed from the base of the PR and between 7bddd3e and 42ef6c4.

📒 Files selected for processing (1)

• src/CLR/Core/TypeSystem.cpp