Porting to GCC 15

The GCC 15 release series differs from previous GCC releases in a number of ways. Some of these are a result of bug fixing, and some old behaviors have been intentionally changed to support new standards, or relaxed in standards-conforming ways to facilitate compilation or run-time performance.

Some of these changes are user visible and can cause grief when porting to GCC 15. This document is an effort to identify common issues and provide solutions. Let us know if you have suggestions for improvements!

Note: GCC 15 has not been released yet, so this document is a work-in-progress.

C++ language issues

Header dependency changes

Some C++ Standard Library headers have been changed to no longer include other headers that were being used internally by the library. As such, C++ programs that used standard library components without including the right headers will no longer compile.

In particular, the following header is used less widely within libstdc++ and may need to be included explicitly when compiling with GCC 15:

For questions related to the use of GCC, please consult these web pages and the GCC manuals. If that fails, the gcc-help@gcc.gnu.org mailing list might help. Comments on these web pages and the development of GCC are welcome on our developer list at gcc@gcc.gnu.org. All of our lists have public archives.

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These pages are maintained by the GCC team. Last modified 2024-08-21.