GH-46531: [C++] Add type_singleton utility function and tests. by harshkumar-2005 · Pull Request #47922 · apache/arrow

harshkumar-2005 · 2025-10-23T14:55:50Z

Rationale for this change

Introduce a type_singleton(Type::type id) utility to create parameter-free DataType instances (such as int32, boolean, utf8, etc.). Returns an error for parameterized types.

Are these changes tested?

Yes, by additional unit tests in type_test.cc.

Are there any user-facing changes?

No.

GitHub Issue: [C++] Add a type_singleton utility function #46531

github-actions · 2025-10-23T14:56:22Z

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

harshkumar-2005 · 2025-10-24T05:02:39Z

@pitrou Cl jobs are awaiting maintainer approval. Please approve to trigger the remaining checks.

harshkumar-2005 · 2025-10-25T05:57:17Z

@pitrou
This PR has 9 workflows pending approval. Kindly review and approve to initiate the workflow runs. Thank you!

github-actions · 2025-10-26T07:39:03Z

⚠️ GitHub issue #46531 has been automatically assigned in GitHub to PR creator.

pitrou

Thanks for doing this @harshkumar-2005 . Please find a couple comments below.

cpp/src/arrow/type_traits.cc

cpp/src/arrow/type_test.cc

cpp/src/arrow/type_traits.h

pitrou · 2026-02-03T14:01:14Z

@harshkumar-2005 Are you using AI for this PR?

pitrou · 2026-02-03T13:58:35Z

cpp/src/arrow/type_test.cc

+
+TEST(TestTypeSingleton, ParameterizedTypes) {
+  // Test error cases - parameterized types
+  std::vector<Type::type> parameterized_types = {


Same comment here: no need to test these exhaustively, only one of them will be enough.

cpp/src/arrow/type_traits.h

pitrou · 2026-02-03T13:59:33Z

cpp/src/arrow/type_traits.cc

+#include "arrow/type.h"
 #include "arrow/util/logging_internal.h"

-namespace arrow {


Why this change?

You still forgot to undo this.

cpp/src/arrow/type_traits.cc

cpp/src/arrow/type.cc

pitrou · 2026-02-03T14:00:42Z

cpp/src/arrow/type.cc

+
+  Visitor visitor;
+  auto status = VisitTypeIdInline(id, &visitor);
+  if (!status.ok()) {


No need for this as the visitor is already returning a Status.

harshkumar-2005 · 2026-02-03T14:06:45Z

@harshkumar-2005 Are you using AI for this PR?

Yes, partially—for understanding a few concepts. The implementation and final code are mine.

pitrou · 2026-02-03T14:08:32Z

@harshkumar-2005 Are you using AI for this PR?

Yes, partially—for understanding a few concepts. The implementation and final code are mine.

Ok, thanks. I was asking because your latest changes seemed unfinished and don't compile at all on CI.

pitrou

@harshkumar-2005 Here are a couple more suggestions. Also, please review and build your own code before submitting, as some changes probably break compilation.

cpp/src/arrow/type.h

pitrou · 2026-02-05T14:03:22Z

cpp/src/arrow/type_test.cc

+    ASSERT_TRUE(type->Equals(*test_case.second))
+        << "Failed on type " << test_case.first << ". Expected "
+        << test_case.second->ToString() << " but got " << type->ToString();


Suggested improvement: you can use AssertTypeEqual to automate the generation of a nice error message if the types don't match.

cpp/src/arrow/type_test.cc

pitrou · 2026-02-05T14:04:15Z

cpp/src/arrow/type_test.cc

+              testing::HasSubstr("is not a parameter-free singleton type"));
+}
+
+TEST(TestTypeSingleton, InvalidType) {


I don't think this test is useful, passing an invalid type id is a programming error.

cpp/src/arrow/type.cc

pitrou · 2026-02-05T14:05:54Z

cpp/src/arrow/type_test.cc

 #include "arrow/type_traits.h"
 #include "arrow/util/checked_cast.h"
 #include "arrow/util/key_value_metadata.h"
+#include "arrow/util/logging.h"


This include doesn't seem actually used?

pitrou · 2026-02-05T14:06:16Z

cpp/src/arrow/type_traits.cc

+#include "arrow/type.h"
 #include "arrow/util/logging_internal.h"

-namespace arrow {


You still forgot to undo this.

pitrou · 2026-02-05T14:06:33Z

cpp/src/arrow/type_traits.cc


 #include "arrow/type_traits.h"
-
+#include "arrow/type.h"


Not sure why this addition is required?

pitrou · 2026-02-05T14:06:45Z

cpp/src/arrow/type_traits.h

 #include <type_traits>
 #include <vector>

+#include "arrow/result.h"


Why these additions? Let's remove them.

github-actions · 2026-02-18T14:54:48Z

⚠️ GitHub issue #46531 has been automatically assigned in GitHub to PR creator.

github-actions · 2026-02-18T14:55:48Z

⚠️ GitHub issue #46531 has been automatically assigned in GitHub to PR creator.

…ing tests

pitrou · 2026-02-18T15:04:36Z

I've pushed some updates to fix compilation and simplify the implementation. Will merge if green.

conbench-apache-arrow · 2026-02-19T03:48:18Z

After merging your PR, Conbench analyzed the 1 benchmarking run that has been run so far on merge-commit 99984fd.

There was 1 benchmark result indicating a performance regression:

Commit Run on arm64-t4g-2xlarge-linux at 2026-02-19 01:58:22Z
- dataset-select (Python) with dataset=nyctaxi_multi_parquet_s3_repartitioned

The full Conbench report has more details. It also includes information about 37 possible false positives for unstable benchmarks that are known to sometimes produce them.

github-actions bot added Component: C++ awaiting review Awaiting review labels Oct 23, 2025

harshkumar-2005 changed the title ~~ARROW-46531: [C++] Add type_singleton utility function and tests~~ GH-46531: [C++] Add type_singleton utility function and tests GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY} Oct 26, 2025

harshkumar-2005 changed the title ~~GH-46531: [C++] Add type_singleton utility function and tests GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}~~ GH-46531: [C++] Add type_singleton utility function and tests. Oct 26, 2025

pitrou requested changes Feb 3, 2026

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harshkumar-2005 force-pushed the ARROW-46531-type-singleton-util branch from a171977 to 98795b2 Compare February 3, 2026 13:23

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pitrou force-pushed the ARROW-46531-type-singleton-util branch from a10dfb1 to 4bb9a23 Compare February 18, 2026 14:55

ARROW-46531: [C++] Add type_singleton utility function and correspond…

0a87cce

…ing tests

pitrou force-pushed the ARROW-46531-type-singleton-util branch from 4bb9a23 to 0a87cce Compare February 18, 2026 14:56

pitrou approved these changes Feb 18, 2026

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pitrou merged commit 99984fd into apache:main Feb 18, 2026
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pitrou mentioned this pull request Feb 18, 2026

[C++] Add a type_singleton utility function #46531

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harshkumar-2005 deleted the ARROW-46531-type-singleton-util branch February 18, 2026 18:55

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Rationale for this change

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harshkumar-2005 commented Oct 23, 2025 •

edited by pitrou

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