> On Nov 8, 2017, at 9:59 PM, Erik Eckstein via swift-dev <swift-dev@swift.org> > wrote: > > > >> On Nov 8, 2017, at 5:27 PM, Johannes Weiß via swift-dev >> <swift-dev@swift.org> wrote: >> >> Hi Daniel, >> >>> On 2 Nov 2017, at 8:15 pm, Daniel Dunbar <daniel_dun...@apple.com> wrote: >>> >>> My personal preference is to: >>> 1. Do nothing for now, but encourage publishing standardized protocols to >>> solve this need. >>> 2. Hope for a future with WMO+LTO magic which recovers the performance, for >>> the case where the entire application ends up using one implementation. >> >> Hmm, but that'll only work if we get 'whole product optimisation', right? > > yes. > > Even when we have cross-module optimizations (which would be comparable to > thin-lto) we could not do that optimization. > >> If we still compile one module at the time I don't think the compiler will >> be able to figure out that there's just one implementation of that protocol >> in the whole program. > > exactly
If you know you're building for an executable target, then it should be theoretically possible to look at the whole system and see that there's a single conformance to a protocol. For the situation Johannes is talking about, maybe this could be information that the build system feeds the compiler, so in a configuration file somewhere you'd say "I want to specialize all uses of the Logger.Logger protocol for the FancyLogger.FancyLogger<MyOutputStream> implementation" instead of relying on the compiler magically deriving it. -Joe _______________________________________________ swift-dev mailing list swift-dev@swift.org https://lists.swift.org/mailman/listinfo/swift-dev
