GH-45144: [C++] use std::atomic<std::shared_ptr> instead of std::atomic_load()/std::atomic_store()

[jonkeane]

Rationale for this change

Replace deprecated calls to quite warnings (turned into errors) on GCC15

What changes are included in this PR?

s/atomic_(load|store)/atomic/g not actually this simple.

Are these changes tested?

Yes

Are there any user-facing changes?

There should be none.

• GitHub Issue: [C++] use std::atomic<std::shared_ptr> instead of std::atomic_load()/std::atomic_store()  #45144

[jonkeane]

@github-actions crossbow submit test-debian-experimental-cpp-gcc-15

[github-actions]

Revision: 8b11038

Submitted crossbow builds: ursacomputing/crossbow @ actions-c4407390b8

Task	Status
test-debian-experimental-cpp-gcc-15

[jonkeane]

This isn't working yet — the change(s) needed aren't just substituting. Looking at some examples and https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2869r0.pdf I need to change the type of result to be wrapped by std::atomic<>

https://github.com/jonkeane/arrow/blob/8b110388819afc433bd9bdbe62c6d1c5a93dc3f8/cpp/src/arrow/array/array_nested.cc#L1080-L1081

But haven't quite found the right place for that yet.

Separately + on the CRAN front, I actually think we might be ok to submit something not compatible with C++20 (but would love a double check of my understanding here 🙏 @kou ): from the log output I see at the end:

Failing compile command: g++-15 -E -I/usr/local/include  -g -O2 -Wall -pedantic -mtune=native -Wno-ignored-attributes -Wno-parentheses -Wp,-D_FORTIFY_SOURCE=3 -fexceptions -fstack-protector-strong -fstack-clash-protection -fcf-protection -std=gnu++17 -xc++ -

Am I reading the -std=gnu++17 part correctly that it's using the C++17 standard (with GNU extensions) and not C++20? I also tried building locally with GCC15 + CMAKE_CXX_STANDARD=17 to see if that built ok. I ended up making a PR to run this on crossbow #45150 and it did get past the atomic issue, but there is a slightly different deprecation treated as an error in google test (Though for CRAN purposes, those aren't built, so that might be ok)

FAILED: src/arrow/CMakeFiles/arrow_testing_objlib.dir/io/test_common.cc.o 
/usr/local/bin/sccache /usr/lib/ccache/g++-15 -DARROW_HAVE_RUNTIME_AVX2 -DARROW_HAVE_RUNTIME_AVX512 -DARROW_HAVE_RUNTIME_BMI2 -DARROW_HAVE_RUNTIME_SSE4_2 -DARROW_HAVE_SSE4_2 -DARROW_TESTING_EXPORTING -DARROW_WITH_TIMING_TESTS -DBOOST_ATOMIC_DYN_LINK -DBOOST_ATOMIC_NO_LIB -DBOOST_FILESYSTEM_DYN_LINK -DBOOST_FILESYSTEM_NO_LIB -DBOOST_PROCESS_HAVE_V2 -DBOOST_PROCESS_NEED_SOURCE -DBOOST_SYSTEM_DYN_LINK -DBOOST_SYSTEM_NO_LIB -I/build/cpp/src -I/arrow/cpp/src -I/arrow/cpp/src/generated -isystem /arrow/cpp/thirdparty/flatbuffers/include -Wredundant-move -Wno-noexcept-type -Wno-self-move  -fdiagnostics-color=always  -Wall -Wno-conversion -Wno-sign-conversion -Wdate-time -Wimplicit-fallthrough -Wunused-result -fno-semantic-interposition -msse4.2  -g -Werror -O0 -ggdb -g1 -std=c++17 -fPIC -DGTEST_HAS_PTHREAD=1 -MD -MT src/arrow/CMakeFiles/arrow_testing_objlib.dir/io/test_common.cc.o -MF src/arrow/CMakeFiles/arrow_testing_objlib.dir/io/test_common.cc.o.d -o src/arrow/CMakeFiles/arrow_testing_objlib.dir/io/test_common.cc
In file included from /usr/include/gtest/internal/gtest-port.h:295,
                 from /usr/include/gtest/gtest-message.h:57,
                 from /usr/include/gtest/gtest-assertion-result.h:46,
                 from /usr/include/gtest/gtest.h:63,
                 from /arrow/cpp/src/arrow/testing/gtest_util.h:33,
                 from /arrow/cpp/src/arrow/io/test_common.cc:33:
/usr/include/c++/15/ciso646:46:4: error: #warning "<ciso646> is deprecated in C++17, use <version> to detect implementation-specific macros" [-Werror=cpp]
   46 | #  warning "<ciso646> is deprecated in C++17, use <version> to detect implementation-specific macros"
      |    ^~~~~~~
cc1plus: all warnings being treated as errors
[560/1252] Building CXX object src/arrow/CMakeFiles/arrow_testing_objlib.dir/ipc/test_common.cc.o
FAILED: src/arrow/CMakeFiles/arrow_testing_objlib.dir/ipc/test_common.cc.o 
/usr/local/bin/sccache /usr/lib/ccache/g++-15 -DARROW_HAVE_RUNTIME_AVX2 -DARROW_HAVE_RUNTIME_AVX512 -DARROW_HAVE_RUNTIME_BMI2 -DARROW_HAVE_RUNTIME_SSE4_2 -DARROW_HAVE_SSE4_2 -DARROW_TESTING_EXPORTING -DARROW_WITH_TIMING_TESTS -DBOOST_ATOMIC_DYN_LINK -DBOOST_ATOMIC_NO_LIB -DBOOST_FILESYSTEM_DYN_LINK -DBOOST_FILESYSTEM_NO_LIB -DBOOST_PROCESS_HAVE_V2 -DBOOST_PROCESS_NEED_SOURCE -DBOOST_SYSTEM_DYN_LINK -DBOOST_SYSTEM_NO_LIB -I/build/cpp/src -I/arrow/cpp/src -I/arrow/cpp/src/generated -isystem /arrow/cpp/thirdparty/flatbuffers/include -Wredundant-move -Wno-noexcept-type -Wno-self-move  -fdiagnostics-color=always  -Wall -Wno-conversion -Wno-sign-conversion -Wdate-time -Wimplicit-fallthrough -Wunused-result -fno-semantic-interposition -msse4.2  -g -Werror -O0 -ggdb -g1 -std=c++17 -fPIC -DGTEST_HAS_PTHREAD=1 -MD -MT src/arrow/CMakeFiles/arrow_testing_objlib.dir/ipc/test_common.cc.o -MF src/arrow/CMakeFiles/arrow_testing_objlib.dir/ipc/test_common.cc.o.d -o src/arrow/CMakeFiles/arrow_testing_objlib.dir/ipc/test_common
In file included from /usr/include/gtest/internal/gtest-port.h:295,
                 from /usr/include/gtest/gtest-message.h:57,
                 from /usr/include/gtest/gtest-assertion-result.h:46,
                 from /usr/include/gtest/gtest.h:63,
                 from /arrow/cpp/src/arrow/testing/gtest_util.h:33,
                 from /arrow/cpp/src/arrow/testing/builder.h:30,
                 from /arrow/cpp/src/arrow/ipc/test_common.cc:38:
/usr/include/c++/15/ciso646:46:4: error: #warning "<ciso646> is deprecated in C++17, use <version> to detect implementation-specific macros" [-Werror=cpp]
   46 | #  warning "<ciso646> is deprecated in C++17, use <version> to detect implementation-specific macros"
      |    ^~~~~~~
cc1plus: all warnings being treated as errors
[561/1252] Building CXX object src/arrow/CMakeFiles/arrow_objlib.dir/scalar.cc.o
[562/1252] Building CXX object src/arrow/CMakeFiles/arrow_objlib.dir/c/bridge.cc.o
[563/1252] Building CXX object src/arrow/CMakeFiles/arrow_objlib.dir/type.cc.o

[kou]

Separately + on the CRAN front, I actually think we might be ok to submit something not compatible with C++20 (but would love a double check of my understanding here 🙏 @kou ):

Right.
The C++17 build reports only warnings not errors. We can ignore them by -DBUILD_WARNING_LEVEL=PRODUCTION.