Re: Earliest version of gcc the project should support as stage1 for gcc 17?

On Fri, Mar 20, 2026 at 10:49 AM Claudio Bantaloukas via Gcc
<[email protected]> wrote:
>
> Title says it all really.
>
> Why am I asking? I'd like to try writing a build that checks stage1
> works with the earliest version of gcc the project wants to support.
>
> https://gcc.gnu.org/install/prerequisites.html currently says:
> - GCC 5.4 or newer has sufficient support for used C++14 features.
> - If you need to build an intermediate version of GCC in order to
> bootstrap current GCC, consider GCC 9.5
>
> Should it use gcc 5.4? Is it time to increase that version?
>
> A look at system gcc versions in major distros:
> - ubuntu from 10 years ago (16.04) had 5.3.1 so that will require an
> intermediate. 20.04 was EOLd last year and it had 9.3.0.
> - Debian 9 had 6.3.0 (and it was EOLd 6 years ago). The latest EOLd
> version is Debian 11 with gcc 10.2.1
> - RHEL 7 had 4.8.5 so that will require an intermediate gcc no matter
> what, RHEL 8 has 8.5.0
> - SUse 15 starts at 7.5
>
> So, if we want to support Suse 15, we could require at least version 7.5
> and consider allowing whatever version of C++ that version supports.
>
> What other systems are you aware of that our users use and care about
> and have sufficient popularity to warrant supporting their system
> compiler (without having to use an intermediate build of gcc to bootstrap).
>
> As an aside, it would be good to have the rationale behind these
> prerequisites documented somewhere. I keep hearing some arguments with
> some variation but some seem handwavy.

I think it's worth checking whatever we currently document, meaning GCC 5.4.
Whether we want to raise that bar is a separate thing - we do want to know
if what is documented is no longer going to work.

From a SUSE POV GCC 7.5 works, SLE12 (which has GCC 4.8.5) is no
longer receiving newer GCC compilers.

Richard.

>
> I hereby pledge to summarize any replies on the wiki.
>
> Cheers,
> Claudio
>