[LLVMdev] [lldb-dev] [cfe-dev] [RFC] Raising LLVM minimum required MSVC version to 2013 for trunk

[Sean Silva]

On Mon, Feb 16, 2015 at 1:05 PM, Chris Bieneman <beanz at apple.com> wrote:

>
> On Feb 16, 2015, at 11:53 AM, Aaron Ballman <aaron at aaronballman.com>
> wrote:
>
> On Mon, Feb 16, 2015 at 2:42 PM, Chris Bieneman <beanz at apple.com> wrote:
>
>
> On Feb 16, 2015, at 10:47 AM, Aaron Ballman <aaron at aaronballman.com>
> wrote:
>
> On Mon, Feb 16, 2015 at 1:37 PM, Chris Bieneman <beanz at apple.com> wrote:
>
> The plan as stated was:
>
> 1) Loop in cfe-dev and lldb-dev (Done!)
> 2) Wait until this email fully circulates in digests and LLVM Weekly so
> that everyone who has an objection can voice it
> 3) If there are no objections, Commit a change to the CMake build which
> errors on old MSVC versions
> 4) Revert and fix buildbots
> 5) Repeat 3 & 4 until no issues
>
>
> It's my understanding that we're past step 5 currently, and waiting to
> do step 6.
>
>
> When I landed the change originally I saw no failures from any public
> bots. I assume Takumi reverted it because there was a failure on a
> non-public bot. Since the change re-landed on Sunday, I don’t think it is
> really safe to assume all non-public bots had been migrated.
>
>
> Takumi's bots are public bots: http://bb.pgr.jp/builders. They also
> happily alert folks in IRC.
>
>
> I’m aware of all this, and was on IRC when I landed the change on Friday,
> which is why I was surprised when I didn’t see any failures, but my commit
> was still reverted (hence my comment about assuming it was non-public).
>
>
> I’m not trying to stand in the way of progress here, but I do feel like
> we’ve kinda thrown the plan to the wind here.
>
>
> I think we're following different plans; I think the progress d0k and
> I have made was done following the plan. I may be wrong with my
> understanding of the plan, however.
>
>
> I definitely think we had different interpretations of the plan. Maybe we
> should be more explicit about timelines for transitions like this in the
> future.
>

IIRC we actually discussed a pretty concrete process for MSVC min version
upgrades when we upped to 2012. I can't seem to find the thread though.

-- Sean


>
>
>
>
> 6) Once the change is live for a week with no issues, update the
> documentation to reflect the minimum required MSVC version as 2013
>
> This really doesn’t make sense if we are landing changes requiring MSVC
> 2013 between steps 3&5. Reverting as needed now that we have a stack of
> changes that is piling up isn’t really viable anymore.
>
>
> You are correct, if we need to revert, it would be challenging. My
> understanding is that we do not need to revert any further, as
> Chapuni's bots were the last ones that needed specific attention. The
> lld and lldb bots may require further attention, but not certain
> whether they require this change to be reverted? Those owners would
> have to speak up with what they'd like to see happen.
>
>
> Hopefull there are no issues, but since this was re-landed on a Sunday
> when a lot of people aren’t around and watching I’m nervous that we may
> have broken things when people weren’t looking.
>
>
> I've not seen any bot-related issues arise in email or IRC yet, and I
> suspect we would have tickled *something* by now if there were major
> problems.
>
>
> I think you’re right, that at this point we are probably safe to assume
> all is well in the world. I didn’t really feel that this was the case when
> I started sending emails on this thread earlier this morning. I’m not sure
> what things are like in your office, but Apple’s campus is a bit of a ghost
> town before 10am on Monday mornings.
>
>
>
>
> So I assume the new plan to just make anyone using MSVC update or they
> can’t build anymore.
>
>
> They couldn't build after step 3 anyway (almost any source changes
> require CMake to rebuild the solutions, so any source fetches getting
> newer code would also get the CMake files requiring a newer version of
> MSVC before the solution can be generated). The repetition part of the
> above steps is for build bots, not all users (though, obviously, if
> there are major users who are stuck and didn't realize it until now,
> we would have to figure out how to handle that).
>
>
> Right, but step 4 is to revert that change. We’ve now basically made it
> prohibitively difficult to revert.
>
>
> Agreed.
>
> Look, I want to use variadic templates as much as the next guy, I’m just
> also wanting to be considerate of our unfortunate colleagues using MSVC.
>
>
> As one of the people who was opposed to this change originally
> specifically for that consideration, I appreciate it (though I would
> not describe us as "unfortunate.”)
>
>
> Don’t take it personally. I kinda view anyone not using Vim and Ninja as
> their development environment as impoverished :-).
>
> -Chris
>
>
> ~Aaron
>
>
>
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