[GitHub] [arrow] bkietz commented on a change in pull request #11013: ARROW-13773: [C++] Cross platform initializer blocks

[GitBox <gi...@apache.org>]

bkietz commented on a change in pull request #11013:
URL: https://github.com/apache/arrow/pull/11013#discussion_r696976143



##########
File path: cpp/src/arrow/util/init.h
##########
@@ -0,0 +1,53 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#pragma once
+
+#include "arrow/util/macros.h"
+
+namespace arrow {
+namespace internal {
+
+#define ARROW_INITIALIZER_NAME(counter) ARROW_CONCAT(arrow_initializer_, counter)
+
+/// Declares a block of code to be executed on load of the library.
+/// The init block can only fail by aborting, so use this with caution.
+///
+///     ARROW_INITIALIZER({
+///       DCHECK_OK(registry->Add(Thing::Make()));
+///     });
+#define ARROW_INITIALIZER(...) \
+  ARROW_INITIALIZER_IMPL(ARROW_INITIALIZER_NAME(__COUNTER__), __VA_ARGS__)
+
+#if !defined(_MSC_VER)
+
+// __attribute__((constructor)) is supported by GCC and Clang, and
+// declares that a function must be executed as part of library initialization.
+#define ARROW_INITIALIZER_IMPL(NAME, ...) \
+  __attribute__((constructor)) void NAME() __VA_ARGS__
+
+#else
+
+// MSVC has no equivalent of __attribute__((constructor)), so instead
+// specify an object whose constructor executes the required code.
+#define ARROW_INITIALIZER_IMPL(NAME, ...) \
+  __declspec(dllexport) class NAME { NAME() __VA_ARGS__ } NAME

Review comment:
       ```suggestion
     __declspec(dllexport) struct NAME { NAME() __VA_ARGS__ } NAME
   ```




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