[PATCH] D47073: Document and Enforce new Host Compiler Policy

Tue Jan 15 12:39:38 PST 2019

jfb added a comment.

In D47073#1358289 <https://reviews.llvm.org/D47073#1358289>, @mehdi_amini wrote:

> In D47073#1358067 <https://reviews.llvm.org/D47073#1358067>, @jfb wrote:
>
> > In D47073#1358066 <https://reviews.llvm.org/D47073#1358066>, @mehdi_amini wrote:
> >
> > > In D47073#1358039 <https://reviews.llvm.org/D47073#1358039>, @jfb wrote:
> > >
> > > > Yes: we want to warn folks early. This is just warning them, and they can opt-out.
> > >
> > >
> > > The current version of the patch would issue a fatal error when using a host clang 3.5, not just a warning 
> > >  (note that clang-3.4 is supposed to support C++14)
> >
> >
> > Yes it's a CMake error. The point is: you won't see it and will ignore it if it's just a CMake warning. What I meant was: we're giving everyone with older compilers a warning that they won't be supported soon. They can opt out and compile this once. Won't be true soon (because we'll move away from C++11). I want them to know ASAP.
>
>
> OK but then this patch is not correct. It should not claim that the compilers aren't supported but that they are deprecated and support will be dropped in the next release.

Rewording along those lines sounds fine.

> Also the two levels (warnings vs errors) is not appropriate to accomplish what you're describing.

I don't understand what you're asking to change here.

> Finally, that still left open the choice of which compiler version the "warning" is issued.

~1.5 years, which per policy can be updated after an llvm-dev discussion.

In D47073#1358290 <https://reviews.llvm.org/D47073#1358290>, @mehdi_amini wrote:

> One release cycle with deprecating the version we're about to remove support for using a discardable cmake error seems like a good idea in general: we should encode this in the policy as well.

Sure.

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https://reviews.llvm.org/D47073