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

[Mehdi AMINI via Phabricator via llvm-commits]

mehdi_amini added a comment.

In D47073#1358640 <https://reviews.llvm.org/D47073#1358640>, @jfb wrote:

> In D47073#1358626 <https://reviews.llvm.org/D47073#1358626>, @mehdi_amini wrote:
>
> > In D47073#1358593 <https://reviews.llvm.org/D47073#1358593>, @jfb wrote:
> >
> > > OK I think we've had more than enough bikeshed, over months, and in-person at the LLVM dev meeting. This is good enough, we want to warn people for the LLVM 8 branch which is tomorrow. Let's get this checked in today. We'll start a discussion on LLVM dev when anything *actually* changes, so nobody needs to panic just yet.
> >
> >
> > I strongly disagree with this right now: this is *not* OK to rush this as is.
> >
> > If you need something in the release, then it can be done in a much less controversial way.
>
>
> What makes you say this is being rushed?


The way you're trying to get this checked in with two reviewers requiring major changes that haven't been addressed.
The fact that the process of discussing which version of the compiler to bump to should happen *before* adding a check, and it hasn't happened for this patch which *actually* change the minimum versions.

> There's agreement that we'll move away from C++11, soon. We'd be irresponsible if we didn't tell developers who build LLVM. That's the only thing the patch does: tell people what we've agreed to do?



1. I asked *multiple* times in this patch *why* and *how* these particular version of the compiler where picked. I still don't know why clang-3.5 would trigger a cmake error.
2. The two levels: `cmake warn` vs `cmake error` are *not* required to achieve what you're describing: i.e. warning people in LLVM 8 that LLVM 9 won't support their compiler. *One* level (cmake error) is plenty enough.

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)





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