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

[Lang Hames via Phabricator via llvm-commits]

lhames added a comment.

>> 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.

Given how long this has been discussed I don't feel like it is being rushed. On the contrary: I would really like to see us land this (or something very much like it in 8.0) to get this process moving.

>> 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.
> 
> This is setting up something new. Yes, we could just have one level for now, but we'll add the second level as soon as we truly move off C++11 (this is clear in the policy!). The patch sets things up properly for the policy we're establishing. It's a boundary value problem, and like all good BVPs we're carving out a small boundary (here, at the initial impulse) to solve the wider problem. The policy is encoded in CMake.

The specifics of how the warning/error are implemented seem like something we could revisit. I would much rather have some mechanism make it in to 8.0 to warn people about these changes, rather than put off any warnings for another release cycle.


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  https://reviews.llvm.org/D47073/new/

https://reviews.llvm.org/D47073