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

On Fri, 20 Mar 2026 at 17:58, Paul Koning via Gcc <[email protected]> wrote:
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> > On Mar 20, 2026, at 6:15 AM, Jakub Jelinek via Gcc <[email protected]> wrote:
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> > On Fri, Mar 20, 2026 at 09:47:08AM +0000, Claudio Bantaloukas via Gcc 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?
> >
> > Yes. No.
> >
> > We don't increase the minimum requirement just for fun, but when it gives
> > significant benefits for the codebase and the earliest supported gcc is
> > still old enough (unlike especially rustc but also LLVM we try not to
> > require too recent stuff for building).
>
> That's an excellent principle.  Do we apply this to other dependencies?  I've noticed the prerequisite version of things like gmp creeping up.  Is that necessary?

They changed last year, and hadn't changed since 2021 before that. The
commit log explains why they were updated:

   contrib/download_prerequisites: Update GMP, MPFR, MPC [PR120237]

   Download newer versions of GMP, MPFR and MPC (the latest); besides the usual
   bug fixes and smaller features, MPFR adds new functions for C23, some of
   which are already used in GCC in the middle (fold-const-call.cc) and in
   Fortran 2023 for the 'pi' trignonometric functions, if MPFR is new enough.

See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120237 for more details.