Use std::optional for host types

[robertmaynard]

Description

cuda::std::optional shouldn't be used for host types such as std::vector as it requires the constructors of the T types to be host+device.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[mythrocks]

LGTM!

[robertmaynard]

/merge

[bdice]

Re-approving additional changes.

[bdice]

There are some failures in CI like this:

In file included from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest-printers.h:115,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest-matchers.h:48,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/internal/gtest-death-test-internal.h:47,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest-death-test.h:43,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest.h:65,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googlemock/include/gmock/internal/gmock-internal-utils.h:50,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googlemock/include/gmock/gmock-actions.h:145,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googlemock/include/gmock/gmock.h:56,
                 from $SRC_DIR/cpp/include/cudf_test/cudf_gtest.hpp:19,
                 from $SRC_DIR/cpp/include/cudf_test/base_fixture.hpp:19,
                 from $SRC_DIR/cpp/tests/io/parquet_common.hpp:19,
                 from $SRC_DIR/cpp/tests/io/parquet_writer_test.cpp:17:
$SRC_DIR/cpp/tests/io/parquet_writer_test.cpp:1033:84: error: invalid initialization of reference of type 'const cuda::std::__4::optional<cudf::io::parquet::detail::ConvertedType>&' from expression of type 'const std::optional<cudf::io::parquet::detail::ConvertedType>'
 1033 |       EXPECT_TRUE(compare_binary(ci.max_values[0], stats.max_value.value(), ptype, ctype) >= 0);
      |                                                                                    ^~~~~
In file included from $SRC_DIR/cpp/tests/io/parquet_writer_test.cpp:17:
$SRC_DIR/cpp/tests/io/parquet_common.hpp:175:93: note: in passing argument 4 of 'int32_t compare_binary(const std::vector<unsigned char>&, const std::vector<unsigned char>&, cudf::io::parquet::detail::Type, const cuda::std::__4::optional<cudf::io::parquet::detail::ConvertedType>&)'
  175 |                        cuda::std::optional<cudf::io::parquet::detail::ConvertedType> const& ctype);
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~

Some additional changes are probably needed.

[robertmaynard]

There are some failures in CI like this:

In file included from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest-printers.h:115,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest-matchers.h:48,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/internal/gtest-death-test-internal.h:47,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest-death-test.h:43,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googletest/include/gtest/gtest.h:65,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googlemock/include/gmock/internal/gmock-internal-utils.h:50,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googlemock/include/gmock/gmock-actions.h:145,
                 from $SRC_DIR/cpp/build/_deps/gtest-src/googlemock/include/gmock/gmock.h:56,
                 from $SRC_DIR/cpp/include/cudf_test/cudf_gtest.hpp:19,
                 from $SRC_DIR/cpp/include/cudf_test/base_fixture.hpp:19,
                 from $SRC_DIR/cpp/tests/io/parquet_common.hpp:19,
                 from $SRC_DIR/cpp/tests/io/parquet_writer_test.cpp:17:
$SRC_DIR/cpp/tests/io/parquet_writer_test.cpp:1033:84: error: invalid initialization of reference of type 'const cuda::std::__4::optional<cudf::io::parquet::detail::ConvertedType>&' from expression of type 'const std::optional<cudf::io::parquet::detail::ConvertedType>'
 1033 |       EXPECT_TRUE(compare_binary(ci.max_values[0], stats.max_value.value(), ptype, ctype) >= 0);
      |                                                                                    ^~~~~
In file included from $SRC_DIR/cpp/tests/io/parquet_writer_test.cpp:17:
$SRC_DIR/cpp/tests/io/parquet_common.hpp:175:93: note: in passing argument 4 of 'int32_t compare_binary(const std::vector<unsigned char>&, const std::vector<unsigned char>&, cudf::io::parquet::detail::Type, const cuda::std::__4::optional<cudf::io::parquet::detail::ConvertedType>&)'
  175 |                        cuda::std::optional<cudf::io::parquet::detail::ConvertedType> const& ctype);
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~

Some additional changes are probably needed.

Thanks. Found the function that needed updating to std::optional