[Buildroot] [for-next 3/3] package/gcc: remove gcc 4.9
Peter Korsgaard
peter at korsgaard.com
Tue Jun 13 22:04:52 UTC 2017
>>>>> "Arnout" == Arnout Vandecappelle <arnout at mind.be> writes:
Hi,
>> I'll wait a little bit for additional feedback on this one. If nobody
>> complains in the next few days, I'm going to apply it.
> GCC 4.9 (or rather, GCC 5) is a bit a special case: libstdc++ had heavy
> ABI-incompatible changes. E.g. at the time Debian switched to it, it was the
> only time I had major breakage in sid. So, the switch from gcc 4.9 to gcc 5
> means that any binary-only C++ program will no longer be usable.
That probably is a bigger issue for a binary distribution like Debian
than for Buildroot though.
> On top of that, gcc 5 introduces many errors (for non-standard-compliant code)
> that were accepted before in gcc 4.9, which makes existing codebases sometimes
> difficult to get built. This, however, happens with each version bump so less of
> an argument against removal.
True. It also breaks older u-boot and Linux kernel versions that didn't
handle > gcc4.x.
> You could say that users with such requirements should keep using their own
> toolchain, but there are useful (security) fixes in libc as well. They could use
> an external toolchain, but then how to build it? Crosstool-NG is a *lot* more
> complicated to use than Buildroot.
But we also don't keep old libc versions around. Would they be Ok with
moving to a new libc version but not to newer gcc version?
> Bottom line: I'd tend to keep gcc 4.9 around for a while. If
> breakage occurs we can disallow it for some architectures. There
> shouldn't be much more maintenance effort than that, I think.
I can follow you, and it is OK for me to keep 4.9 around for a little
while longer. We always have this tradeoff between stability and adding
new features / cleanups, and I do think people should be moving to the
LTS version (and plan in time for a yearly migration to the new LTS) if
they want stability and fixes for a longer period, just like they
(hopefully) do for their Linux kernel.
We should imho drop 4.9 before the next LTS though.
--
Bye, Peter Korsgaard
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