Pin swift-crypto for the Swift CI matrix (#9412) The Swift test job pulls in grpc-swift-2 -> grpc-swift-nio-transport -> swift-nio-ssl -> swift-crypto, and this package ships no Package.resolved, so that whole graph is resolved afresh on every run. On 2026-10-15 it resolved swift-crypto 5.0.1 (released three days earlier) and "Test Swift Linux (6.2)" turned red before a single line of FlatBuffers' Swift code was compiled: Sources/Crypto/HPKE/Ciphersuite/HPKE-AEAD.swift:27:6: error: unknown attribute 'nonexhaustive' 5.x declares swift-tools-version 6.2, which is why only the 6.2 job selects it; the 6.0 and 6.1 jobs prune it and keep building. The 6.2.x toolchains then reject the `@nonexhaustive` that 5.x uses, a combination swift-crypto does not exercise because it builds on nightly. Restrict the test-only graph to 4.0.0 ..< 4.4.0, which resolves to 4.3.0: the last 4.x release that declares swift-tools-version 6.0 and so builds with every toolchain in the matrix. 4.4+ asks for 6.1 and would break the 6.0 job, and the whole 4.x line is free of `@nonexhaustive`. Co-authored-by: Derek Bailey <derekbailey@google.com>
diff --git a/Package.swift b/Package.swift index 4139903..6c1b808 100644 --- a/Package.swift +++ b/Package.swift
@@ -75,6 +75,17 @@ .package( url: "https://github.com/grpc/grpc-swift-nio-transport.git", from: "2.0.0"), + // swift-crypto arrives through grpc-swift-nio-transport -> swift-nio-ssl + // and is otherwise resolved afresh on every build, because this package + // ships no Package.resolved. 5.x asks for swift-tools-version 6.2, so only + // the 6.2 CI job selects it - and then fails to compile it, because 5.x + // uses `@nonexhaustive`, which the 6.2.x toolchains do not accept yet. + // Stay on the last 4.x release that still builds with every toolchain in + // the Swift CI matrix (4.3.0 declares swift-tools-version 6.0; 4.4+ asks + // for 6.1 and would drop the 6.0 job). + .package( + url: "https://github.com/apple/swift-crypto.git", + "4.0.0" ..< "4.4.0"), ] #endif }