GH-47447: [C++] Fix replace_with_mask for null type arrays

[AnkitAhlawat7742]

Rationale for this change

replace_with_mask crashes when called with null type arrays because a code path incorrectly returns Status::OK() from a function with return type Result<int64_t>.
This PR fixes the issue by ensuring the function returns a valid int64_t value instead of Status::OK() for successful execution.

What changes are included in this PR?

1. Fixed the replace_with_mask kernel implementation for null type arrays.
2. Replaced the invalid Status::OK() return path with a valid int64_t result.
3. Prevented construction of Result<int64_t> with an OK Status.

Are these changes tested?

Yes, manually run the test case

Are there any user-facing changes?

No

This PR contains a "Critical Fix".

This change fixes a crash in replace_with_mask when operating on null type arrays. The crash occurs due to an invalid successful return path internally constructing Result with Status::OK().

• GitHub Issue: [C++][Python] replace_with_mask crashes when null type inputs are used #47447

[github-actions]

⚠️ GitHub issue #47447 has been automatically assigned in GitHub to PR creator.

[AnkitAhlawat7742]

Hi @raulcd ,
Could you please re-run the failed job? i see download build timed out while downloading the ORC dependency (orc-2.2.1.tar.gz)

 --- LOG END ---
          error: downloading 'https://dlcdn.apache.org/orc/orc-2.2.1/orc-2.2.1.tar.gz' failed
          status_code: 22
          status_string: "HTTP response code said error"
          log:
          --- LOG BEGIN ---
            Trying 151.101.2.132:443...

[AnkitAhlawat7742]

Hi @raulcd ,
Please review the changes ,let me know if any modification needed

[pitrou]

Thanks @AnkitAhlawat7742 for this PR.

Can you add some C++ tests in the existing file vector_replace_test.cc?
You can get some inspiration from the existing TestReplaceBoolean.

[AnkitAhlawat7742]

Thanks @AnkitAhlawat7742 for this PR.

Can you add some C++ tests in the existing file vector_replace_test.cc? You can get some inspiration from the existing TestReplaceBoolean.

HI @pitrou ,
Thanks for the review ..!!
I have updated the python Test case and added the new test case in vector_replace_test file .and thanks for the reference of existing class

[AnkitAhlawat7742]

Hi @pitrou and @raulcd ,
Please review the changes, when you get a chance. I noticed a CI failure in the Windows build but confirmed it is unrelated to my changes.

[AnkitAhlawat7742]

Hi @pitrou and @raulcd,
just a gentle ping on this PR when you get a chance. please review it once again ...happy to make any changes if needed!

cc @AlenkaF @rok @jorisvandenbossche

[AnkitAhlawat7742]

Hi @kou ,
Please review the PR as well

[Copilot]

Pull request overview

This PR fixes a crash in the C++ replace_with_mask kernel when operating on NullType arrays (GH-47447), where a Result<int64_t> path incorrectly attempted to return Status::OK(). The fix ensures the kernel returns a valid int64_t and produces a valid output for null arrays, and adds regression tests in both C++ and Python.

Changes:

• Fix NullType replace_with_mask implementation to return a valid int64_t (and set output as ArrayData) instead of returning Status::OK() from a Result<int64_t> function.
• Add C++ regression tests covering replace_with_mask on NullType.
• Add Python regression test reproducing the original crash scenario.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
cpp/src/arrow/compute/kernels/vector_replace.cc	Fixes NullType ReplaceMaskImpl to return a valid int64_t and sets output as ArrayData, preventing the invalid Result<T>(Status::OK()) construction.
cpp/src/arrow/compute/kernels/vector_replace_test.cc	Adds a dedicated NullType test fixture and ReplaceWithMask test cases to prevent regressions in the C++ kernel.
python/pyarrow/tests/test_compute.py	Adds a Python regression test for pc.replace_with_mask with pa.null() arrays to ensure the crash is fixed end-to-end.

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[kou]

+1