GH-41891: [C++] Clean up implicit fallthrough warnings

[WillAyd]

Rationale for this change

Helps clean up warnings, and at least one of these looks like a subtle bug that may confuse developers

What changes are included in this PR?

Added break statements where case statements were previously falling through

Are these changes tested?

Builds cleanly

Are there any user-facing changes?

No

• GitHub Issue: [C++] Clean up fallthrough Warnings #41891

[github-actions]

⚠️ GitHub issue #41891 has been automatically assigned in GitHub to PR creator.

[pitrou]

I'm curious, why did you close this PR?

[WillAyd]

Not sure - happy to reopen and take another look if there is interest in it

[pitrou]

It's probably a desirable even though minor cleanup.

[WillAyd]

@pitrou do we need to run this through crossbow or is it good as is?

[pitrou]

Since we're nearing a release, let's do a Crossbow run :-)

[pitrou]

@github-actions crossbow submit -g cpp

[pitrou]

@github-actions crossbow submit wheelcp312

[github-actions]

Revision: 53ac63e

Submitted crossbow builds: ursacomputing/crossbow @ actions-9bcc922651

Task	Status
example-cpp-minimal-build-static
example-cpp-minimal-build-static-system-dependency
example-cpp-tutorial
test-alpine-linux-cpp
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-cuda-cpp-ubuntu-20.04-cuda-11.2.2
test-cuda-cpp-ubuntu-22.04-cuda-11.7.1
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-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-13-bundled
test-ubuntu-24.04-cpp-gcc-14
test-ubuntu-24.04-cpp-minimal-with-formats
test-ubuntu-24.04-cpp-thread-sanitizer

[github-actions]

Revision: 53ac63e

Submitted crossbow builds: ursacomputing/crossbow @ actions-f6fb796edd

Task	Status
wheel-macos-monterey-cp312-cp312-arm64
wheel-macos-ventura-cp312-cp312-amd64
wheel-manylinux-2-28-cp312-cp312-amd64
wheel-manylinux-2-28-cp312-cp312-arm64
wheel-manylinux-2014-cp312-cp312-amd64
wheel-manylinux-2014-cp312-cp312-arm64
wheel-windows-cp312-amd64

[pitrou]

@WillAyd Do you want to merge this PR? Please make sure you use the merge script, not the GitHub button.

[WillAyd]

OK sure no problem. So stepping through that, I just need to run

./merge_arrow_pr.sh 41892

right?

[pitrou]

Yes!

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 4 benchmarking runs that have been run so far on merge-commit b8eae60.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 12 possible false positives for unstable benchmarks that are known to sometimes produce them.