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).
The reason to go to gcc 5.4 [1] (which already causes significant pain, several
CompilerFarm machines still have system gcc 4.8.5) was to be able to use
C++14 and so not be as limited in constexpr functions as in C++11.
The next step would be to be able to use C++17 features (but which ones are
the ones we can't live without in the sources right now?), but that
would mean requiring GCC 9. That is IMHO quite premature.
We've switched to C++14 requirement in GCC 15 and between GCC 5 and 9 it
is 4 years, so I'd expect switching roughly in GCC 19 rather than GCC 17.
[1] I think some 5.3.1 versions can be just fine too, depends on from when,
there were some important C++14 bugfixes between 5.3.0 and 5.4.0.
Jakub
