<div dir="ltr"><br><br><div class="gmail_quote"><div dir="ltr">On Mon, Jul 20, 2015 at 1:37 PM Juergen Ributzka <<a href="mailto:juergen@apple.com">juergen@apple.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">Wow, this went of topic very quickly ;-)<div><br></div></div></blockquote><div><br></div><div>It did. I am sorry about that :)</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div></div><div>As you know I am very interested in an stable API (C and/or C++) for LLVM, but maybe we should discuss this in a separate thread. Designing a good stable API from scratch will take some time and until that point I want to document our current “tribal knowledge”. I will post a patch as you suggested.</div></div><div style="word-wrap:break-word"><div><br></div></div></blockquote><div><br></div><div>Thanks. Given the direction it's taken and the positive feedback I've gotten on the existing C API we might want to document it as "in flux" :)</div><div><br></div><div>That said, here's how I see this happening if we were to go the direction I'm proposing:</div><div><br></div><div>I think we should bite the bullet and say that the growth we've had in the C API is past what we were originally promising and just call the existing C API the "bindings" api. From there we can move the LTO headers to a new directory (insert bikeshed) and say that the existing code in llvm-c isn't stable. We can then migrate the things we want to be stable into a new directory with real stability guarantees. I'm seeing an API (possibly versioned) with a much lower surface area here similar, possibly, to the LTO stuff or libclang.<br></div><div><br></div><div><div>I totally believe that existing clients could break through this and I want to minimize that as much as possible as it's our responsibility here. I think, in general, we've been stable enough in the existing C API to keep it going until we can define something that's actually stable that we can migrate clients to though.</div></div><div><br></div><div>Thoughts?</div><div><br></div><div>-eric</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div></div><div>—Juergen</div><div><br></div></div><div style="word-wrap:break-word"><div><div><div><div><div><blockquote type="cite"><div>On Jul 20, 2015, at 1:08 PM, Eric Christopher <<a href="mailto:echristo@gmail.com" target="_blank">echristo@gmail.com</a>> wrote:</div><br></blockquote></div></div></div></div></div></div><div style="word-wrap:break-word"><div><div><div><div><div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><br></div><div>Part (most?) of the point of having a stable API is as a way of decoupling the development processes of two separate projects (modulo well-documented release-to-release updating). Requiring our users to add tests in our tree doesn't really achieve much decoupling. </div></div></div></div></div></blockquote><div><br></div></div></div><div style="word-wrap:break-word"><div><div>I’m not sure there is much “coupling” here. The point is that we expose a C API that is supposed to be stable but is not well tested. And some part of the C API is just a wrapper around the C++ and hasn’t really been designed to be “stable” in time.</div><div>It seems also that we don’t really know what part of the C API really needs to be stable and is important for the users, so I read Pete’s proposal as “let’s collect the current use-cases and make them tests in LLVM, so that we define what is part of the stable C API and so that we won’t (inadvertently) break valid use cases".</div><div><br></div></div></div></blockquote><div><br></div><div>Yeah, this is just terrible though for all of the reasons I raised in my email and as you even say here "And some part of the C API is just a wrapper around the C++ and hasn’t really been designed to be “stable” in time."</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><div><br></div><div>As of having this in-tree or out-of-tree, I’m not sure about that and there is a trade-off.</div><div><br></div></div></div></blockquote><div><br></div><div>I'm regretting ever saying "out of tree" here as I don't think it's the main issue, rather the splitting of the "bindings" style of api that we see a lot of in the C API directory and the more solid ones that we see from libclang and liblto.</div><div><br></div><div>-eric </div></div></div></div></blockquote></div></div></div></div></div></div><div style="word-wrap:break-word"><div><div><div><div><div><blockquote type="cite"><div>
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