Fix macos 14 build

Author: xtyxtyx

Sources/Subprocess/Atomic.swift

@@ -11,7 +11,7 @@
 
 #if canImport(Synchronization)
 import Synchronization
-#else
+#endif  // canImport(Synchronization)
 
 #if canImport(os)
 internal import os
@@ -28,7 +28,6 @@ internal import C.os.lock
 import WinSDK
 #endif  // canImport(os)
 
-#endif  // canImport(Synchronization)
 
 internal struct AtomicBox: Sendable, ~Copyable {
     internal typealias BitwiseXorFunc = (OutputConsumptionState) -> OutputConsumptionState
@@ -37,21 +36,26 @@ internal struct AtomicBox: Sendable, ~Copyable {
 
     internal init() {
         #if canImport(Synchronization)
-        guard #available(macOS 15, *) else {
-            fatalError("Unexpected configuration")
-        }
-        let box = Atomic(UInt8(0))
-        self.storage = {
-            return { input in
-                return box._bitwiseXor(input)
-            }
-        }
+        let hasSynchronization = true
         #else
-        let state = LockedState(OutputConsumptionState(rawValue: 0))
-        self.storage = {
-            return state._bitwiseXor
-        }
+        let hasSynchronization = false
         #endif
+
+        if hasSynchronization, #available(macOS 15, *) {
+            let box = Atomic(UInt8(0))
+            self.storage = {
+                return { input in
+                    return box._bitwiseXor(input)
+                }
+            }
+        } else {
+            let state = LockedState(OutputConsumptionState(rawValue: 0))
+            self.storage = {
+                 return { input in
+                    return state._bitwiseXor(input)
+                }
+            }
+        }
     }
 
     internal func bitwiseXor(
@@ -78,7 +82,8 @@ extension Atomic where Value == UInt8 {
         self = Atomic(initialValue.rawValue)
     }
 }
-#else
+#endif
+
 // Fallback to LockedState if `Synchronization` is not available
 extension LockedState where State == OutputConsumptionState {
     init(_ initialValue: OutputConsumptionState) {
@@ -237,5 +242,3 @@ extension LockedState where State == Void {
 }
 
 extension LockedState: @unchecked Sendable where State: Sendable {}
-
-#endif

Sources/_SubprocessCShims/process_shims.c

@@ -236,7 +236,7 @@ static int _subprocess_spawn_prefork(
         *pid = childPid;
         // Read from the pipe until pipe is closed
         // either due to exec succeeds or error is written
-        while (true) {
+        for (;;) {
             int childError = 0;
             ssize_t read_rc = read(pipefd[0], &childError, sizeof(childError));
             if (read_rc == 0) {