> On Aug 25, 2016, at 9:38, Douglas Gregor <dgre...@apple.com> wrote: > >> >> On Aug 24, 2016, at 3:57 PM, Jordan Rose <jordan_r...@apple.com >> <mailto:jordan_r...@apple.com>> wrote: >> >> Hey, all. I’m here to propose predefining a macro __swift__ when C code is >> compiled with Swift. We’ve gotten a few requests for it in the past and >> haven’t done it so that people don’t write header files that arbitrarily >> restrict features when used from Swift, or check for "Swift" when they >> really should be checking for modules support, or Objective-C mode, or >> nullability support. (Or worse, they guard code under __swift__ and then >> don’t ever test it, leading to failures to import the module from Swift.) >> >> However, with Swift 3, it’s now become important for Objective-C authors to >> be able to control how their APIs look in modern Swift 3 without disrupting >> existing clients on Swift 2.3. (Or just because Swift 3 style looks >> out-of-place in Swift 2.3.) The most obvious way to do this would be to >> define a macro that has the Swift version in it. For Swift version X.Y.Z, we >> could use something like >> >> -D__swift__=XYYZZ >> >> e.g. >> >> -D__swift__=30001 >> >> for Swift 3.0.1. >> >> This is option (1). > > Option (1) sounds good to me. We don’t need to make this complicated.
Okay. Next question: two digits or three digits for the minor and patch versions? - Two digits: if we ever switch to year/month combinations like C/C++, those will be higher values (unless we get to Swift 20 first). - Three digits: better for "fake" versions like 3.0.100. Jordan
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