[C++] std::aligned_storage is deprecated since C++23

[vient]

Describe the bug, including details regarding any error messages, version, and platform.

include/arrow/util/aligned_storage.h:140:17: warning: 'aligned_storage<16, 8>' is deprecated [-Wdeprecated-declarations]
  140 |   typename std::aligned_storage<sizeof(T), alignof(T)>::type data_;

Since it is in headers, it triggers when compiling user code with -std=c++23. Not a bug yet but it may be removed completely from C++26.

Seen with clang++-18.

Component(s)

C++

[pitrou]

@vient We're using C++17, what is the suggested replacement for this?
I'll note that https://en.cppreference.com/w/cpp/types/aligned_storage is completed useless as it doesn't explain why it's deprecated.

[vient]

https://stackoverflow.com/questions/71828288/why-is-stdaligned-storage-to-be-deprecated-in-c23-and-what-to-use-instead

// To replace std::aligned_storage
template <typename T>
class MyContainer {
private:
    //std::aligned_storage_t<sizeof(T), alignof(T)> t_buff;
    alignas(T) std::byte t_buff[sizeof(T)];
};

¯\_(ツ)_/¯

[pitrou]

Issue resolved by pull request 45019
#45019

[pitrou]

@sjoubert Can you post a message here so that we can assign this issue to you?

[sjoubert]

@sjoubert Can you post a message here so that we can assign this issue to you?

Present! Thanks for merging the fix.