Fix check for enclosing NewClassTree

[msridhar]

Fixes #1523

Our previous check was broken when state.getPath() pointed at a sub-tree of a constructor call within an anonymous class; the constructor call is also a NewClassTree.

Summary by CodeRabbit

Release Notes

• Bug Fixes

  • Improved handling of anonymous class type resolution in generics checking.

• Tests

  • Added test case for constructor calls with this parameter from anonymous classes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: 0c81d680-f0c2-4b10-95dd-cb3b8fc77d5d

📥 Commits

Reviewing files that changed from the base of the PR and between 9c08bc5 and e0213ae.

📒 Files selected for processing (2)

• nullaway/src/main/java/com/uber/nullaway/generics/GenericsChecks.java
• nullaway/src/test/java/com/uber/nullaway/jspecify/GenericsTests.java

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Walkthrough

This PR fixes a crash in NullAway when handling constructor calls with this from within anonymous inner classes. The fix updates the getTypeForSymbol method in GenericsChecks.java to use upward traversal of the TreePath to locate the correct anonymous NewClassTree, replacing a direct lookup approach that failed in nested scenarios. A corresponding test case is added to verify the fix handles the previously crashing code pattern.

Possibly related PRs

• Improve handling and error messages when using this inside an anonymous class #1305: Threads VisitorState into getTreeType and related paths to correctly resolve "this" in anonymous classes
• Initial handling of constructor diamond operators #1464: Implements path-aware NewClassTree and getTreeType machinery with diamond-inference handling in GenericsChecks
• Add more instance fields to GenericsChecks #1256: Converts GenericsChecks utilities to instance methods and fields, affecting the same module's internal architecture

Suggested labels

jspecify

Suggested reviewers

• yuxincs
• lazaroclapp

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main code change: fixing the check for enclosing NewClassTree in GenericsChecks, which directly addresses the crash reported in issue #1523.
Linked Issues check	✅ Passed	The PR successfully resolves issue #1523 by replacing the broken enclosing NewClassTree check with an upward TreePath traversal that correctly handles constructor calls nested inside anonymous classes.
Out of Scope Changes check	✅ Passed	All changes are directly in scope: GenericsChecks.java fixes the broken enclosing NewClassTree detection logic, and GenericsTests.java adds a test case for the exact scenario from issue #1523.

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✨ 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 issue-1523

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[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.48%. Comparing base (9c08bc5) to head (e0213ae).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...ava/com/uber/nullaway/generics/GenericsChecks.java	71.42%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1524      +/-   ##
============================================
- Coverage     88.48%   88.48%   -0.01%     
- Complexity     2841     2843       +2     
============================================
  Files           103      103              
  Lines          9487     9489       +2     
  Branches       1902     1905       +3     
============================================
+ Hits           8395     8396       +1     
  Misses          531      531              
- Partials        561      562       +1     

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