Fix build errors on Apple platforms

.gitignore

@@ -1,5 +1,6 @@
 # Swift
 .build*/
+.swiftpm/
 
 # VSCode
 launch.json

Sources/Example/main.swift

@@ -16,18 +16,20 @@ if SystemdHelpers.isSystemdService {
     logger.info("Not running as a systemd service...")
 }
 
-logger.info("Adding SystemdService to run as part of a ServiceGroup...")
-let serviceGroup = ServiceGroup(
-    configuration: .init(
-        services: [
-            .init(service: SystemdService())
-        ],
-        gracefulShutdownSignals: [.sigterm],
-        logger: logger
+if #available(iOS 16.0, tvOS 16.0, watchOS 9.0, *) {
+    logger.info("Adding SystemdService to run as part of a ServiceGroup...")
+    let serviceGroup = ServiceGroup(
+        configuration: .init(
+            services: [
+                .init(service: SystemdService())
+            ],
+            gracefulShutdownSignals: [.sigterm],
+            logger: logger
+        )
     )
-)
 
-logger.info("Send SIGTERM signal to exit the service")
-try await serviceGroup.run()
+    logger.info("Send SIGTERM signal to exit the service")
+    try await serviceGroup.run()
+}
 
 logger.info("Exiting application...")

Sources/Systemd/Utility.swift

@@ -1,37 +1,37 @@
 #if canImport(Glibc)
     import Glibc
-#endif
 
-/// Compute the prefix sum of `seq`.
-private func scan<S: Sequence, U>(_ seq: S, _ initial: U, _ combine: (U, S.Element) -> U) -> [U] {
-    var result: [U] = []
-    result.reserveCapacity(seq.underestimatedCount)
-    var runningResult = initial
-    for element in seq {
-        runningResult = combine(runningResult, element)
-        result.append(runningResult)
+    /// Compute the prefix sum of `seq`.
+    private func scan<S: Sequence, U>(_ seq: S, _ initial: U, _ combine: (U, S.Element) -> U) -> [U] {
+        var result: [U] = []
+        result.reserveCapacity(seq.underestimatedCount)
+        var runningResult = initial
+        for element in seq {
+            runningResult = combine(runningResult, element)
+            result.append(runningResult)
+        }
+        return result
     }
-    return result
-}
 
-func withArrayOfIovecs<R>(_ args: [String], _ body: ([iovec]) -> R) -> R {
-    let argsCounts = Array(args.map { $0.utf8.count + 1 })
-    let argsOffsets = [0] + scan(argsCounts, 0, +)
-    let argsBufferSize = argsOffsets.last!
-    var argsBuffer: [UInt8] = []
-    argsBuffer.reserveCapacity(argsBufferSize)
-    for arg in args {
-        argsBuffer.append(contentsOf: arg.utf8)
-        argsBuffer.append(0)
-    }
-    return argsBuffer.withUnsafeMutableBufferPointer {
-        argsBuffer in
-        let ptr = UnsafeMutableRawPointer(argsBuffer.baseAddress!).bindMemory(
-            to: CChar.self, capacity: argsBuffer.count
-        )
-        let iovecs: [iovec] = zip(argsCounts, argsOffsets).map { count, offset in
-            iovec(iov_base: ptr + offset, iov_len: count - 1)
+    func withArrayOfIovecs<R>(_ args: [String], _ body: ([iovec]) -> R) -> R {
+        let argsCounts = Array(args.map { $0.utf8.count + 1 })
+        let argsOffsets = [0] + scan(argsCounts, 0, +)
+        let argsBufferSize = argsOffsets.last!
+        var argsBuffer: [UInt8] = []
+        argsBuffer.reserveCapacity(argsBufferSize)
+        for arg in args {
+            argsBuffer.append(contentsOf: arg.utf8)
+            argsBuffer.append(0)
+        }
+        return argsBuffer.withUnsafeMutableBufferPointer {
+            argsBuffer in
+            let ptr = UnsafeMutableRawPointer(argsBuffer.baseAddress!).bindMemory(
+                to: CChar.self, capacity: argsBuffer.count
+            )
+            let iovecs: [iovec] = zip(argsCounts, argsOffsets).map { count, offset in
+                iovec(iov_base: ptr + offset, iov_len: count - 1)
+            }
+            return body(iovecs)
         }
-        return body(iovecs)
     }
-}
+#endif