How to import macros using methods other than SwiftPM

[allevato (Tony Allevato)]

@rintaro

Note that, currently, the only supported way of using macros is using SwiftPM's .macro target. Compiler options related to macro plugins are not guaranteed to be stable, nor officially documented. It is possible to make macro plugin manually and use it if really want, but again it's not guaranteed to be stable.

Are there any blockers to publicizing and documenting the driver flags for passing in macros?

IMO, there should not be any public-facing officially supported language features that are only accessible through SwiftPM or through an -Xfrontend backdoor flag; the swiftc driver interface for this should be stabilized at the same time as the rest of the feature set.