[llvm-dev] A Short Policy Proposal Regarding Host Compilers

Thu Jan 10 16:30:08 PST 2019

I'm a bit puzzled as of why would a fix period of time be the best option
to automatically cut support for older compilers?

Historically I believe we've been looking at a combination of:

1) What new feature we gain by dropping support for a given version of the
compiler
2) What major OS out there have available (possibly through PPA?).

And balance the two aspects.

What is the motivation for changing this approach?

-- 
Mehdi

On Mon, Jan 7, 2019 at 4:46 PM JF Bastien via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> I’d like us to move forward with something along the lines Erich proposed
> back in May, ideally early enough in the LLVM 8 release process that people
> testing the release will be able to provide feedback.
>
> Are there any remaining concerns?
>
>
> > On May 23, 2018, at 6:21 AM, Keane, Erich via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Hi all-
> > I just wanted to bump this again, I know I sent it out on a Friday :)  I
> realize this is a minor code change with significant implications, so it
> seems to me that I should ensure it gets extensive exposure.
> > See the review here: https://reviews.llvm.org/D47073
> > -Erich
> >
> > -----Original Message-----
> > From: Keane, Erich
> > Sent: Friday, May 18, 2018 8:26 AM
> > To: llvm-dev at lists.llvm.org
> > Subject: RE: [llvm-dev] A Short Policy Proposal Regarding Host Compilers
> >
> > I've heard just about zero opposition to this, so I've put a code review
> together here: https://reviews.llvm.org/D47073 With the intent of either
> implementing this policy change, or encouraging further discussion/bikeshed.
> >
> > Thanks all!
> > -Erich
> >
> > -----Original Message-----
> > From: Brooks Davis [mailto:brooks at freebsd.org]
> > Sent: Sunday, May 13, 2018 10:34 AM
> > To: Keane, Erich <erich.keane at intel.com>
> > Cc: llvm-dev at lists.llvm.org
> > Subject: Re: [llvm-dev] A Short Policy Proposal Regarding Host Compilers
> >
> > On Fri, May 11, 2018 at 01:37:22PM +0000, Keane, Erich via llvm-dev
> wrote:
> >> Hi All-
> >> As we all know, the C++14 discussion is flaring up again.  Chandler
> brought up that he would like a concrete plan to switch.  In my opinion,
> this is insufficient, as it will result in us simply having this discussion
> AGAIN next release.  Instead, I would prefer us to have a concrete Policy
> on our host compilers.  That way, changes like this are unsurprising to our
> users, and advance our codebase sufficiently.  I believe the arguments
> for/against upgrading have been made repeatedly, so I won't repeat them
> here.  My proposal is thus:
> >>
> >> Starting with the Clang 7.0 release, we will officially support any
> major release of our host compilers (MSVC, GCC, Clang, ?ICC?) released in
> the past 3* years from our previous branch date to give trunk-developers
> time to transition (so for 7.0, 3 years before January 3, 2018).  This will
> be enforced via the CMake CheckCompilerVersion script (ala
> https://reviews.llvm.org/D46723).  ADDITIONALLY, a CMake warning will be
> issued for any major release less than 1.5* years old to give our users
> sufficient time to transition/upgrade their compilers.  Finally, our
> dependent C++ version will be the best released standard officially
> supported by the collection of compilers (for example, we'd support -C++20
> if all compilers had std=c++20 or eqiv, but NOT std=c++2a).
> >>
> >> The 3-years/1.5 years would result in our minimum GCC/Clang becoming:
> >> GCC5.1/Clang3.6.  We would WARN on anything older than GCC7.1/Clang3.8
> >
> > Historically 3/1.5 would have caused us problems on FreeBSD, but we're
> moving to supporting all architectures via an external toolchain[0] so I
> don't think it will have a major impact.  We'll have to amend our statement
> of which systems you can bootstrap from to include the need to install a
> compiler package in some cases (or be more aggressive about merging new
> compiler versions to stable branches).
> >
> > -- Brooks
> >
> > [0] Some of them purely external due to a lack of viable LLVM support
> and a policy against GPLv3 licenses in the tree.
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190110/ccb34077/attachment.html>