This week, I tried using Buildroot on my new Fedora 42 system, which comes with GCC 15. Right away, the build failed when compiling the package host-m4.
After looking into it, I found that GCC 15 has stricter rules that cause some Buildroot packages to break-not just m4, but also others like gmp. This means if you are using Buildroot on a Linux system with GCC 15, you might run into similar problems.
What to do?
There are patches available to fix these issues, including one I submitted for m4. You can find them here:
https://lists.buildroot.org/pipermail/buildroot/2025-April/777274.html
What’s next?
Hopefully, these problems will be fixed in the official Buildroot updates soon. Until then, applying these patches will help you build successfully with GCC 15.
If you use Buildroot with the latest Linux and GCC versions, keep an eye out for updates and patches like these!
Update [May 5, 2025]:
This patch has now been committed upstream to buildroot.
It will be applied as a workaround only when host gcc 15 is detected.
For more details, please check the full commit here:
https://gitlab.com/buildroot.org/buildroot/-/commit/7a07a9d155b8f601d68f07ee0ed1dc8d48907644