[PATCH] D64326: Retire VS2015 Support

Mon Jul 8 11:34:18 PDT 2019

rnk accepted this revision.
rnk added a comment.

All policy aside, let's drop VS 2015 so we can simplify our alignas usage. lgtm :)

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In D64326#1573909 <https://reviews.llvm.org/D64326#1573909>, @probinson wrote:

> So, the point of this is to be able to remove certain workarounds, rather than advance the language feature set, IIUC.
>  Note that not all workarounds can be removed if we claim our minimum is the very first release of VS2017; see my r361502, to work around something that all of the bots were happy with.
>  I'm "once burnt, twice shy" about this, because we're not verifying that our claimed minimum build compilers are actually usable.
>  What is the minimum version of VS2017 used by any bot?  Perhaps we should assert that as the minimum, which then makes it my fault for having a too-old build compiler.

As someone who maintains one of these buildbots, I'm actually more interested in testing the latest update, since that's what new developers are more likely to be using, and it provides early detection of compatibility issues, such as https://llvm.org/PR42027. We could set up more testing in more configs, but there are certain aspects of buildbot that don't scale very well. Every new config generates a unique email per failure, bots take care and feeding, they ultimately cost money, etc. And the minimum version only approximates the set of bugs that may be present in any release between the oldest and the newest supported release.

I think it's enough to document which major versions are known to work, and that for best results, developers should use the latest update available of one of those releases. I think I just made a very long argument which can be summarized as, let's just maintain the status quo. Sorry. >_>

Actually, how about this: what if we linked from the documentation to some buildbot page that exposes the precise toolchain versions that are actively being used for testing? That way if a user has problems they can consult this list and rule out that environmental factor. You can infer some version info from some bot logs, but it's far from accessible.

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https://reviews.llvm.org/D64326