| 24 Oct 2025 |
 emily | I'm just saying there are a fair few differences | 01:24:57 |
| emily | AFAICT, the __SPI_AVAILABLE stuff is just identical to __API_AVAILABLE for internal stuff and defined away for external stuff | 01:25:44 |
| emily | not sure why they do it in such a convoluted way given that but I guess it's what their scripts make convenient | 01:25:58 |
| emily | also not sure why they define away the availability for internal stuff | 01:26:17 |
| emily | * also not sure why they define away the availability for external stuff | 01:26:19 |
| emily | not like it hides the definitions | 01:26:23 |
 Randy Eckenrode | https://github.com/freebsd/freebsd-src/commit/c844ab67178719d956f1571f70bae84edc49cf72 | 01:29:08 |
| Randy Eckenrode | I guess Apple is catching up changes from FreeBSD 11 …. | 01:29:15 |
| emily | oh. I think I understand why SPI_AVAILABLE is defined away for public users | 01:33:41 |
| emily | it seems like it's used to annotate things defined in the source releases, not system stuff | 01:34:46 |
| emily | so __SPI_AVAILABLE(macos(15.0), …) just means "this wasn't in dyld before macOS 15.0", I guess (why that's useful I don't know) | 01:35:18 |
| emily | when we're building the source releases ourselves it seems the public SDK behaviour of eliding those availability checks is exactly the correct thing | 01:35:48 |
| emily | https://github.com/search?q=repo%3Aapple-oss-distributions%2Flibdispatch%20dispatch_time_from_nsec&type=code another example | 01:36:15 |
| emily | so… all the darwin.AvailabilityVersions version of it would do is incorrectly mark stuff we're building as unavailable depending on SDK version, essentially | 01:37:10 |
| Randy Eckenrode | It probably depends on whether we’re linking to the implementation in one of the source releases or to the symbol exported by the system in the SDK. | 01:37:19 |
| emily | right | 01:37:28 |
| emily | but I think this stuff is mostly not exported by the SDK? | 01:37:36 |
| emily | because it's all stuff in private headers | 01:37:40 |
| Randy Eckenrode | The symbols are. | 01:37:42 |
| Randy Eckenrode | They’re in the text-based stubs. | 01:37:48 |
| emily | right, ok, dispatch_time_from_nsec is there | 01:38:06 |
| emily | it seems at least very contextual whether you'd want them to expand to availability checks | 01:38:16 |
| emily | like any time you're compiling something directly you don't want SPI_AVAILABLE on its own definitions | 01:38:48 |
| emily | what probably makes sense is rewriting SPI_ → API_ inside the XNU headers etc. themselves | 01:39:15 |
| Randy Eckenrode | I’d only want to elide them if we were actually building and using libdispatch on Darwin in lieu of using the system library. I would want those SPI checks in this case when using the system library because they may not be available on older releases. I ran into at least one of those with the 14.0 min version that required patching to check availability. | 01:39:25 |
| emily | libdispatch was just an example | 01:39:34 |
| emily | dyld is more relevant | 01:39:50 |
