GH-43787: [C++] Register the new Opaque extension type by default

cpp/src/arrow/CMakeLists.txt

@@ -374,6 +374,7 @@ set(ARROW_SRCS
     datum.cc
     device.cc
     extension_type.cc
+    extension/bool8.cc
     pretty_print.cc
     record_batch.cc
     result.cc
@@ -906,7 +907,6 @@ endif()
 
 if(ARROW_JSON)
   arrow_add_object_library(ARROW_JSON
-                           extension/bool8.cc
                            extension/fixed_shape_tensor.cc
                            extension/opaque.cc
                            json/options.cc

cpp/src/arrow/extension/CMakeLists.txt

@@ -15,22 +15,16 @@
 # specific language governing permissions and limitations
 # under the License.
 
-add_arrow_test(test
-               SOURCES
-               bool8_test.cc
-               PREFIX
-               "arrow-extension-bool8")
+set(CANONICAL_EXTENSION_TESTS bool8_test.cc)
 
-add_arrow_test(test
-               SOURCES
-               fixed_shape_tensor_test.cc
-               PREFIX
-               "arrow-fixed-shape-tensor")
+if(ARROW_JSON)
+  list(APPEND CANONICAL_EXTENSION_TESTS fixed_shape_tensor_test.cc opaque_test.cc)
+endif()
 
 add_arrow_test(test
                SOURCES
-               opaque_test.cc
+               ${CANONICAL_EXTENSION_TESTS}
                PREFIX
-               "arrow-extension-opaque")
+               "arrow-canonical-extensions")
 
 arrow_install_all_headers("arrow/extension")

cpp/src/arrow/extension/bool8.h

@@ -15,6 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
+#pragma once
+
 #include "arrow/extension_type.h"
 
 namespace arrow::extension {

cpp/src/arrow/extension/bool8_test.cc

@@ -19,7 +19,6 @@
 #include "arrow/io/memory.h"
 #include "arrow/ipc/reader.h"
 #include "arrow/ipc/writer.h"
-#include "arrow/testing/extension_type.h"
 #include "arrow/testing/gtest_util.h"
 
 namespace arrow {

cpp/src/arrow/extension/fixed_shape_tensor.h

@@ -15,6 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
+#pragma once
+
 #include "arrow/extension_type.h"
 
 namespace arrow {

cpp/src/arrow/extension/opaque.h

@@ -15,6 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
+#pragma once
+
 #include "arrow/extension_type.h"
 #include "arrow/type.h"
 

cpp/src/arrow/extension/opaque_test.cc

@@ -25,7 +25,6 @@
 #include "arrow/ipc/reader.h"
 #include "arrow/ipc/writer.h"
 #include "arrow/record_batch.h"
-#include "arrow/testing/extension_type.h"
 #include "arrow/testing/gtest_util.h"
 #include "arrow/type_fwd.h"
 #include "arrow/util/checked_cast.h"
@@ -169,7 +168,6 @@ TEST(OpaqueType, MetadataRoundTrip) {
 TEST(OpaqueType, BatchRoundTrip) {
   auto type = internal::checked_pointer_cast<extension::OpaqueType>(
       extension::opaque(binary(), "geometry", "adbc.postgresql"));
-  ExtensionTypeGuard guard(type);
 
   auto storage = ArrayFromJSON(binary(), R"(["foobar", null])");
   auto array = ExtensionType::WrapArray(type, storage);

cpp/src/arrow/extension_type.cc

@@ -27,9 +27,10 @@
 #include "arrow/array/util.h"
 #include "arrow/chunked_array.h"
 #include "arrow/config.h"
-#ifdef ARROW_JSON
 #include "arrow/extension/bool8.h"
+#ifdef ARROW_JSON
 #include "arrow/extension/fixed_shape_tensor.h"
+#include "arrow/extension/opaque.h"
 #endif
 #include "arrow/status.h"
 #include "arrow/type.h"
@@ -143,17 +144,21 @@ static std::once_flag registry_initialized;
 namespace internal {
 
 static void CreateGlobalRegistry() {
+  // Register canonical extension types
+
   g_registry = std::make_shared<ExtensionTypeRegistryImpl>();
+  std::vector<std::shared_ptr<DataType>> ext_types{extension::bool8()};
 
 #ifdef ARROW_JSON
-  // Register canonical extension types
-  auto fst_ext_type =
-      checked_pointer_cast<ExtensionType>(extension::fixed_shape_tensor(int64(), {}));
-  ARROW_CHECK_OK(g_registry->RegisterType(fst_ext_type));
-
-  auto bool8_ext_type = checked_pointer_cast<ExtensionType>(extension::bool8());
-  ARROW_CHECK_OK(g_registry->RegisterType(bool8_ext_type));
+  ext_types.push_back(extension::fixed_shape_tensor(int64(), {}));
+  ext_types.push_back(extension::opaque(null(), "", ""));
 #endif
+
+  // Register canonical extension types
+  for (const auto& ext_type : ext_types) {
+    ARROW_CHECK_OK(
+        g_registry->RegisterType(checked_pointer_cast<ExtensionType>(ext_type)));
+  }
 }
 
 }  // namespace internal

python/pyarrow/tests/test_extension_type.py

@@ -1693,9 +1693,8 @@ def test_opaque_type(pickle_module, storage_type, storage):
     arr = pa.ExtensionArray.from_storage(opaque_type, storage)
     assert isinstance(arr, opaque_arr_class)
 
-    with registered_extension_type(opaque_type):
-        buf = ipc_write_batch(pa.RecordBatch.from_arrays([arr], ["ext"]))
-        batch = ipc_read_batch(buf)
+    buf = ipc_write_batch(pa.RecordBatch.from_arrays([arr], ["ext"]))
+    batch = ipc_read_batch(buf)
 
     assert batch.column(0).type.extension_name == "arrow.opaque"
     assert isinstance(batch.column(0), opaque_arr_class)