Change LIST column offsets from size_type to int32 in benchmarks and gtests

[davidwendt]

Description

Follow on work to #23607 includes changes to cpp/benchmarks and cpp/tests where cudf::size_type is used for LIST column offsets and replaced with int32_t instead.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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📥 Commits

Reviewing files that changed from the base of the PR and between e0df26a and 17f2ac6.

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• cpp/tests/io/parquet_reader_test.cpp

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📝 Walkthrough

Summary by CodeRabbit

• Tests

  • Updated list-column test fixtures and utilities to use explicit 32-bit offset values.
  • Added coverage confirming binary data read as lists uses 32-bit offsets, including large intermediate offsets.
  • Preserved existing test scenarios, expected results, and overflow assertions across supported operations.
  • Improved consistency between test offsets and list-column storage behavior.

• Chores

  • Refreshed copyright years and attribution notices where applicable.

Walkthrough

The change standardizes list-column offset construction and access on explicit INT32 and int32_t types across benchmark code, utility code, and tests. Copyright notices and one empty-column type construction are also updated.

Changes

List offset alignment

Layer / File(s)	Summary
Offset access and benchmark construction cpp/benchmarks/lists/copying/scatter_lists.cu, cpp/tests/utilities/column_utilities.cu	Benchmark offsets and utility iterators now use explicit INT32 and int32_t types.
List construction and copying tests cpp/tests/copying/*, cpp/tests/groupby/collect_list_tests.cpp, cpp/tests/hashing/*, cpp/tests/structs/*, cpp/tests/utilities_tests/*	List, nested-list, and struct-list fixtures now construct offsets with int32_t.
Serialization and table IO fixtures cpp/tests/io/*	JSON, Parquet, and cudf-table fixtures now use int32_t list and map offsets. The Parquet reader tests add coverage for INT32 offsets after large-string intermediate processing.
Algorithm and transformation fixtures cpp/tests/lists/*, cpp/tests/reductions/*, cpp/tests/reshape/*, cpp/tests/rolling/*, cpp/tests/sort/*, cpp/tests/transform/*	Expected and constructed list offsets now use int32_t. Copyright notices are updated in affected files.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 17f2a

This PR updates LIST offset types in benchmarks and tests without introducing an actionable correctness, runtime, deployment, or availability risk; it is merge-ready after normal checks and review.

Possibly related PRs

• NVIDIA/cudf#23652: Adds overflow checks for output offsets in list APIs. It concerns list offset handling but changes a different code path.

Suggested reviewers: wence-, bdice, vuule

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 6.52% 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
Title check	✅ Passed	The title clearly summarizes the main change: replacing LIST column offsets from size_type with int32 in benchmarks and tests.
Description check	✅ Passed	The description directly explains the offset type changes in benchmarks and tests and identifies the follow-up context.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[davidwendt]

/merge