GH-47317: [C++][C++23][Gandiva] Use pointer for Cache test

[kou]

Rationale for this change

gandiva::Cache requires pointer type for value type.

What changes are included in this PR?

Use std::shared_ptr<std::string> not std::string for ValueType.

Are these changes tested?

Yes.

Are there any user-facing changes?

No.

• GitHub Issue: [C++][C++23][Gandiva] cpp/src/gandiva/cache.h:54:35: error: use of deleted function #47317

[github-actions]

⚠️ GitHub issue #47317 has been automatically assigned in GitHub to PR creator.

[kou]

Passed with GCC 12:

https://github.com/apache/arrow/actions/runs/16926330455/job/47962616526?pr=47318#step:6:4091

100% tests passed, 0 tests failed out of 106

I'll update to Debian 13 from 12 to use more recent GCC.

[WillAyd]

I think the Meson failure will require #47041 to pass

[kou]

Hmm. It seems that newer (unreleased RapidJSON) is installed by conda:

https://github.com/apache/arrow/actions/runs/16934205748/job/47986801327?pr=47318#step:6:346

rapidjson                 1.1.0.post20240409      h3f2d84a_2    conda-forge

but it's not detected by Meson:

https://github.com/apache/arrow/actions/runs/16934205748/job/47986801327?pr=47318#step:6:502

Run-time dependency rapidjson found: NO (tried pkgconfig)

I think that it's a problem.

Anyway, let's work on it as a separated task.

I'll merge this because I could confirm that this PR can fix GCC 12 + C++23 problem and GCC 14 + C++23 has another problems.

[WillAyd]

Ah cool. I didn't realize conda patched RapidJSON like that.

I guess the problem is that Meson is using pkg-config to search for the dependency, and being header-only there is no .pc file distributed with it (I think this is intentional, but if not I don't see a .pc file when installing locally via conda).

Per Meson's dependency detection logic, I wonder if we just need to be more clear that rapidjson should be detected as a system dependency, and let it search the PATH for the header:

https://mesonbuild.com/Dependencies.html#dependency-detection-method

[kou]

It seems that conda's rapidjson package https://anaconda.org/conda-forge/rapidjson includes RapidJSON.pc:

https://anaconda.org/conda-forge/rapidjson/1.1.0.post20240409/download/linux-64/rapidjson-1.1.0.post20240409-h3f2d84a_2.conda

$ find . -name '*.pc'
./lib/pkgconfig/RapidJSON.pc

It seems that we need to use dependency('RapidJSON') not dependency('rapidjson').

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 4 benchmarking runs that have been run so far on merge-commit 6660e84.

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

The full Conbench report has more details.