Cover anonymous class type arguments and modeled call-site returns

[vlsi]

Follow-up tests for #1746, which #1722 fixed. Offered per #1746 (comment)

Why

overrideExplicitlyTypedAnonymousClassWithNestedGenericTypes, added by #1722, covers an anonymous class that implements an interface at @Nullable String and overrides List<T>. The diamond form and an array element take paths that test does not reach, and #1746 reported both as false positives.

#1722 also stopped nullableReturns() from stripping whitespace out of astubx signatures, which lets 36 entries of jspecify-jdk.astubx match for the first time — every one of them differing only by a space inside a wildcard bound such as ? super K. Those entries feed hasNullableReturn at every call site, not only at override checks, and mapComputeOverrideUsesJSpecifyModel discarded the result of map.compute(...), so nothing pinned the call-site direction.

What

Two new tests in GenericsTests: a diamond anonymous class whose overrides wrap the type variable in List<T>, and an anonymous class in both the explicit and the diamond form whose overrides wrap it in an array.

mapComputeOverrideUsesJSpecifyModel now also dereferences the result of map.compute(...). The bare call stays: an unmarked line asserts that no diagnostic fires there, which is how the existing test pins that a BiFunction<String, @Nullable String, @Nullable String> argument is accepted. A // BUG: marker on that line would have consumed any other diagnostic it produced.

Optional.orElseGet is the other way to pin the call-site direction, and this change leaves it alone. JSpecifyLibraryModelsTests.optionalOrElseGet passes today, but LibraryModelsHandler still carries the hand-written model for that method commented out under #1616, so removing the @Ignore is a call for a maintainer rather than for this pull request.

How to verify

./gradlew :nullaway:test --tests "com.uber.nullaway.jspecify.GenericsTests" --tests "com.uber.nullaway.JSpecifyJDKModelsTest"

Every assertion here fails at 70da029, the commit before #1722. The two array blocks needed checking one marker at a time, because the harness stops at the first unmarked line that carries an error.

Summary by CodeRabbit

• Bug Fixes
  • Improved nullability analysis for Map.compute results, correctly identifying values that may be null.
  • Preserved @Nullable annotations when analyzing anonymous classes with nested generic types, diamond syntax, and arrays of type variables.

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📒 Files selected for processing (2)

• nullaway/src/test/java/com/uber/nullaway/JSpecifyJDKModelsTest.java
• nullaway/src/test/java/com/uber/nullaway/jspecify/GenericsTests.java

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Walkthrough

Expanded JSpecify test coverage in two areas. The JDK model test now checks that the result of Map.compute is treated as nullable. GenericsTests adds coverage for nullable type arguments in diamond anonymous classes with nested generic types and for array types based on nullable type variables. The tests verify accepted nullable overrides and diagnostics for mismatched non-nullable overrides.

Suggested reviewers: msridhar, dbwiddis

Merge Risk: ⚪ Minimal · up to 2206c

This change expands regression coverage for existing nullability behavior without modifying shipped code or runtime behavior; no actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
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.
Title check	✅ Passed	The title clearly summarizes both main changes: coverage for anonymous class type arguments and modeled call-site returns.
Description check	✅ Passed	The description directly explains the added tests, the modeled return-value coverage, the issue context, and the verification command.

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[msridhar]

Thanks!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.65%. Comparing base (c1221cb) to head (18f3fb2).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1777   +/-   ##
=========================================
  Coverage     87.65%   87.65%           
  Complexity     3291     3291           
=========================================
  Files           109      109           
  Lines         11084    11084           
  Branches       2247     2247           
=========================================
  Hits           9716     9716           
  Misses          641      641           
  Partials        727      727           

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