ARROW-17803: [C++] Use [[nodiscard]]

[pitrou]

C++17 supports the standard attribute [[nodiscard]], use that instead of the clang-specific __attribute__((warn_unused_result)).

[pitrou]

@js8544 For the record, it seems this version works around the GCC parser issue.

[js8544]

@js8544 For the record, it seems this version works around the GCC parser issue.

Nice!

[pitrou]

Linker issue which suggests the ARROW_FRIEND_EXPORT macro isn't right...
https://github.com/pitrou/arrow/actions/runs/3098917212/jobs/5017418044#step:7:1065

D:/a/_temp/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: src/arrow/CMakeFiles/arrow_testing_shared.dir/testing/gtest_util.cc.obj:gtest_util.cc:(.text$_ZN7testing13PrintToStringISt10shared_ptrIN5arrow6SchemaEEEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKT_[_ZN7testing13PrintToStringISt10shared_ptrIN5arrow6SchemaEEEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKT_]+0x69): undefined reference to `arrow::PrintTo(arrow::Schema const&, std::ostream*)'
D:/a/_temp/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: src/arrow/CMakeFiles/arrow_testing_shared.dir/compute/exec/test_util.cc.obj:test_util.cc:(.text+0x893): undefined reference to `arrow::compute::PrintTo(arrow::compute::Expression const&, std::ostream*)'
D:/a/_temp/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: src/arrow/CMakeFiles/arrow_testing_shared.dir/compute/exec/test_util.cc.obj:test_util.cc:(.text+0x988): undefined reference to `arrow::compute::PrintTo(arrow::compute::Expression const&, std::ostream*)'

[github-actions]

https://issues.apache.org/jira/browse/ARROW-17803

[pitrou]

Revision: 95c9694bc6a38241a0cbaee9c310b21363662081

Submitted crossbow builds: ursacomputing/crossbow @ nodiscard-2

Task	Status
test-alpine-linux-cpp
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-debian-10-cpp-amd64
test-debian-10-cpp-i386
test-debian-11-cpp-amd64
test-debian-11-cpp-i386
test-fedora-35-cpp
test-ubuntu-18.04-cpp
test-ubuntu-18.04-cpp-release
test-ubuntu-18.04-cpp-static
test-ubuntu-20.04-cpp
test-ubuntu-20.04-cpp-17
test-ubuntu-20.04-cpp-bundled
test-ubuntu-20.04-cpp-thread-sanitizer
test-ubuntu-22.04-cpp

[ursabot]

Benchmark runs are scheduled for baseline = f477a97 and contender = 5256e43. 5256e43 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Finished ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Failed ⬇️1.09% ⬆️0.14%] test-mac-arm
[Failed ⬇️1.37% ⬆️0.27%] ursa-i9-9960x
[Finished ⬇️0.25% ⬆️0.0%] ursa-thinkcentre-m75q
Buildkite builds:
[Finished] 5256e434 ec2-t3-xlarge-us-east-2
[Failed] 5256e434 test-mac-arm
[Failed] 5256e434 ursa-i9-9960x
[Finished] 5256e434 ursa-thinkcentre-m75q
[Finished] f477a972 ec2-t3-xlarge-us-east-2
[Failed] f477a972 test-mac-arm
[Failed] f477a972 ursa-i9-9960x
[Finished] f477a972 ursa-thinkcentre-m75q
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java

[ursabot]

['Python', 'R'] benchmarks have high level of regressions.
ursa-i9-9960x