BwL1289 opened a new pull request, #47328: URL: https://github.com/apache/arrow/pull/47328
### Rationale for this change Arrow’s C++ codebase currently targets an older C++ standard. Moving to C++23 helps keep the project aligned with modern compiler defaults, enables new language features, and ensures continued compatibility with upcoming compiler versions. During this upgrade, several forward declaration patterns used in the codebase became invalid under C++23 rules, requiring changes to maintain build correctness. ### What changes are included in this PR? This PR updates code to resolve forward declaration errors triggered by C++23 compliance checks. Specifically, it corrects invalid or outdated forward declarations that are rejected by C++23. Applies the fixes in: - `cpp/src/arrow/acero/asof_join_node.cc` - `cpp/src/arrow/filesystem/mockfs.cc` - `cpp/src/arrow/flight/types.h` ### Are these changes tested? Yes. ### Are there any user-facing changes? No. Closes https://github.com/apache/arrow/issues/47207. CC @kou, @kennedynguyen1 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
