GH-41783: [C++] Make git-dependent definitions internal

[pitrou]

Rationale for this change

Exposing the ARROW_GIT_ID and ARROW_GIT_DESCRIPTION preprocessor variables in our public headers tends to make incremental builds less efficient, since those values change very often during development.

Also, these values don't need to be preprocessor variables since they're just strings: you can't write useful #if directives with them. Instead, they can be inspected using GetBuildInfo().

Are these changes tested?

By existing builds and tests.

Are there any user-facing changes?

Use cases depending on these preprocessor variables, which is unlikely, may break. They can be fixed by calling arrow::GetBuildInfo() instead.

• GitHub Issue: [C++] Make git-dependent preprocessor definitions internal #41783

[github-actions]

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}

In the case of PARQUET issues on JIRA the title also supports:

PARQUET-${JIRA_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[pitrou]

@github-actions crossbow submit -g cpp

[github-actions]

Revision: 1f2709b

Submitted crossbow builds: ursacomputing/crossbow @ actions-500c735934

Task	Status
test-alpine-linux-cpp
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-cuda-cpp
test-debian-12-cpp-amd64
test-debian-12-cpp-i386
test-fedora-39-cpp
test-ubuntu-20.04-cpp
test-ubuntu-20.04-cpp-bundled
test-ubuntu-20.04-cpp-minimal-with-formats
test-ubuntu-20.04-cpp-thread-sanitizer
test-ubuntu-22.04-cpp
test-ubuntu-22.04-cpp-20
test-ubuntu-22.04-cpp-emscripten
test-ubuntu-22.04-cpp-no-threading
test-ubuntu-24.04-cpp
test-ubuntu-24.04-cpp-gcc-14

[github-actions]

⚠️ GitHub issue #41783 has been automatically assigned in GitHub to PR creator.

[pitrou]

@kou Does this look ok to you?

[kou]

+1

Ah, good point. I missed it.

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 7 benchmarking runs that have been run so far on merge-commit 9185d7d.

There weren't enough matching historic benchmark results to make a call on whether there were regressions.

The full Conbench report has more details.