specs: correct mobile Cgo conclusion — iOS is not feasible either#127
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An implementation attempt for #125 disproved the spec's iOS conclusion. iOS fails on two independent, unfixable-from-here blockers: - purego refuses to build for ios under CGO_ENABLED=0 (is_ios.go tripwire), so the library cannot compile Cgo-free once it imports purego/objc. - Go's iOS port forces external (C) linking; even an empty program fails 'GOOS=ios CGO_ENABLED=0 go build'. No iOS artifact links without a C toolchain. The original feasibility check ('go build std') was a false positive: it compiles packages but never links and never pulls in purego. Corrected conclusion: both iOS and Android keep Cgo; no source change.
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Corrects the merged mobile Cgo spec (#123). Implementing #125 disproved its iOS conclusion.
What changed
The spec said iOS was actionable (purego/objc on
UIPasteboard, mirroring darwin #117) and only Android stayed Cgo. That's wrong. iOS cannot drop Cgo either, for two independent reasons — both verified by attempting the implementation:purego/is_ios.go(ios && !cgo) is a deliberate compile-time tripwire (_PUREGO_REQUIRES_CGO_ON_IOS). Once the iOS backend importspurego/objc,GOOS=ios CGO_ENABLED=0 go build .fails to compile. Still true on latest (v0.10.1).func main(){}failsGOOS=ios CGO_ENABLED=0 go buildwithios/arm64 requires external (cgo) linking. darwin (non-iOS) internal-links fine, which is exactly why darwin: remove the Cgo / C-toolchain dependency (purego) (#69) #117 worked and iOS can't.Why the original check was a false positive
The spec's iOS proof was
GOOS=ios CGO_ENABLED=0 go build stdpassing — butgo build stdcompiles packages without linking and without pulling in purego, sidestepping both blockers. The erratum documents the correct check (build the real package with its FFI dep, and link a binary) as a lesson for future platform specs.Result
Docs-only.