Check for output offsets int32 overflow in list APIs

[davidwendt]

Description

Adds int32 overflow check logic to list column functions when building output offsets by replacing calls to thrust::exclusive_scan with cudf::detail::size_to_offsets which returns the total size (last element) as an int64 value and then comparing it to max(int32) and throwing an exception as appropriate.
This was found while working on related size_type as offsets type cleanup work.

Checklist

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

[coderabbitai]

📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes

  • Added validation to prevent list operations from exceeding the maximum supported 32-bit size.
  • Operations now report an overflow error instead of producing invalid offsets when results are too large.

• Maintenance

  • Updated copyright notices.

Walkthrough

The CUDA list concatenation and interleaving paths now use sizes_to_offsets for offset construction and reject totals above the maximum int32_t range. Copyright notices were updated.

Changes

List offset construction and validation

Layer / File(s)	Summary
Offset construction and bounds validation cpp/src/lists/combine/concatenate_rows.cu, cpp/src/lists/interleave_columns.cu	Both paths replace Thrust exclusive scans with cudf::detail::sizes_to_offsets and throw std::overflow_error when generated offsets exceed int32_t limits. Required headers and copyright notices were updated.

Estimated code review effort: 2 (Simple) | ~10 minutes

Mergeability Score: ⚪ Minimal · up to 94616

The change is localized to overflow handling in list APIs, with no concrete merge-blocking risk identified; it is merge-ready after normal checks.

Possibly related PRs

• NVIDIA/cudf#23607: Modifies list-offset handling in the same two CUDA files and adds related int32_t offset checks.

Suggested reviewers: shrshi, bdice, mythrocks, pointkernel, ttnghia

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: checking for int32 overflow in output offsets for list APIs.
Description check	✅ Passed	The description accurately explains the overflow checks, API replacement, exception behavior, and test coverage.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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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[coderabbitai]

🔇 Additional comments (3)

cpp/src/lists/combine/concatenate_rows.cu (2)

2-2: LGTM!

Also applies to: 13-13

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114-122: 📐 Maintainability & Code Quality

⚠️ Unverified finding
Sandbox verification was unavailable.

Verify coverage for offset construction.

The supplied cohort contains no test or benchmark files. Verify that the full PR adds tests for empty inputs, null lists, sliced lists, normal totals, int32_t boundary totals, and overflowing totals for both paths.

As per coding guidelines, **/*: “Add unit tests and unit benchmarks.” Based on learnings, list tests must include boundary sizes, null values, and sliced columns.

cpp/src/lists/interleave_columns.cu (1)

2-2: LGTM!

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 5ff6e72a-c5a1-4a32-a248-9806ce4a9309

📥 Commits

Reviewing files that changed from the base of the PR and between 0b57a3b and 9461695.

📒 Files selected for processing (2)

• cpp/src/lists/combine/concatenate_rows.cu
• cpp/src/lists/interleave_columns.cu