[WIP] Adopt lifetime annotations for owned resources.

Package.swift

@@ -366,6 +366,8 @@ extension Array where Element == PackageDescription.SwiftSetting {
 
       .enableUpcomingFeature("InferIsolatedConformances"),
 
+      .enableExperimentalFeature("Lifetimes"),
+
       // When building as a package, the macro plugin always builds as an
       // executable rather than a library.
       .define("SWT_NO_LIBRARY_MACRO_PLUGINS"),

Sources/Testing/ABI/EntryPoints/SwiftPMEntryPoint.swift

@@ -54,9 +54,7 @@ public func __swiftPMEntryPoint(passing args: __CommandLineArguments_v0? = nil)
   // Ensure that stdout is line- rather than block-buffered. Swift Package
   // Manager reroutes standard I/O through pipes, so we tend to end up with
   // block-buffered streams.
-  FileHandle.stdout.withUnsafeCFILEHandle { stdout in
-    _ = setvbuf(stdout, nil, _IOLBF, Int(BUFSIZ))
-  }
+  _ = setvbuf(FileHandle.stdout.unsafeCFILEHandle, nil, _IOLBF, Int(BUFSIZ))
 #endif
 
   return await entryPoint(passing: args, eventHandler: nil)

Sources/Testing/ExitTests/ExitTest.swift

@@ -700,13 +700,9 @@ extension ExitTest {
   ///   file handle could not be converted to a string.
   private static func _makeEnvironmentVariable(for fileHandle: borrowing FileHandle) -> String? {
 #if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
-    return fileHandle.withUnsafePOSIXFileDescriptor { fd in
-      fd.map(String.init(describing:))
-    }
+    fileHandle.unsafePOSIXFileDescriptor.map(String.init(describing:))
 #elseif os(Windows)
-    return fileHandle.withUnsafeWindowsHANDLE { handle in
-      handle.flatMap { String(describing: UInt(bitPattern: $0)) }
-    }
+    fileHandle.unsafeWindowsHANDLE.flatMap { String(describing: UInt(bitPattern: $0)) }
 #else
 #warning("Platform-specific implementation missing: additional file descriptors unavailable")
     return nil
@@ -879,15 +875,15 @@ extension ExitTest {
         var stdoutWriteEnd: FileHandle?
         if exitTest._observedValues.contains(\.standardOutputContent) {
           try FileHandle.makePipe(readEnd: &stdoutReadEnd, writeEnd: &stdoutWriteEnd)
-          stdoutWriteEnd?.withUnsafeCFILEHandle { stdout in
+          if let stdout = stdoutWriteEnd?.unsafeCFILEHandle {
             _ = setvbuf(stdout, nil, _IOLBF, Int(BUFSIZ))
           }
         }
         var stderrReadEnd: FileHandle?
         var stderrWriteEnd: FileHandle?
         if exitTest._observedValues.contains(\.standardErrorContent) {
           try FileHandle.makePipe(readEnd: &stderrReadEnd, writeEnd: &stderrWriteEnd)
-          stderrWriteEnd?.withUnsafeCFILEHandle { stderr in
+          if let stderr = stderrWriteEnd?.unsafeCFILEHandle {
             _ = setvbuf(stderr, nil, _IONBF, Int(BUFSIZ))
           }
         }

Sources/Testing/ExitTests/SpawnProcess.swift

@@ -120,34 +120,32 @@ func spawnExecutable(
       // Forward standard I/O streams and any explicitly added file handles.
       var highestFD = max(STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO)
       func inherit(_ fileHandle: borrowing FileHandle, as standardFD: CInt? = nil) throws {
-        try fileHandle.withUnsafePOSIXFileDescriptor { fd in
-          guard let fd else {
-            throw SystemError(description: "A child process cannot inherit a file handle without an associated file descriptor. Please file a bug report at https://github.com/swiftlang/swift-testing/issues/new")
-          }
-          if let standardFD, standardFD != fd {
-            _ = posix_spawn_file_actions_adddup2(fileActions, fd, standardFD)
-          } else {
+        guard let fd = fileHandle.unsafePOSIXFileDescriptor else {
+          throw SystemError(description: "A child process cannot inherit a file handle without an associated file descriptor. Please file a bug report at https://github.com/swiftlang/swift-testing/issues/new")
+        }
+        if let standardFD, standardFD != fd {
+          _ = posix_spawn_file_actions_adddup2(fileActions, fd, standardFD)
+        } else {
 #if SWT_TARGET_OS_APPLE
-            _ = posix_spawn_file_actions_addinherit_np(fileActions, fd)
+          _ = posix_spawn_file_actions_addinherit_np(fileActions, fd)
 #else
-            // posix_spawn_file_actions_adddup2() will automatically clear
-            // FD_CLOEXEC after forking but before execing even if the old and
-            // new file descriptors are equal. This behavior is supported by
-            // Glibc ≥ 2.29, FreeBSD, OpenBSD, and Android (Bionic) and is
-            // standardized in POSIX.1-2024 (see https://pubs.opengroup.org/onlinepubs/9799919799/functions/posix_spawn_file_actions_adddup2.html
-            // and https://www.austingroupbugs.net/view.php?id=411).
-            _ = posix_spawn_file_actions_adddup2(fileActions, fd, fd)
+          // posix_spawn_file_actions_adddup2() will automatically clear
+          // FD_CLOEXEC after forking but before execing even if the old and new
+          // file descriptors are equal. This behavior is supported by
+          // Glibc ≥ 2.29, FreeBSD, OpenBSD, and Android (Bionic) and is
+          // standardized in POSIX.1-2024 (see https://pubs.opengroup.org/onlinepubs/9799919799/functions/posix_spawn_file_actions_adddup2.html
+          // and https://www.austingroupbugs.net/view.php?id=411).
+          _ = posix_spawn_file_actions_adddup2(fileActions, fd, fd)
 #if canImport(Glibc) && !os(FreeBSD) && !os(OpenBSD)
-            if _slowPath(glibcVersion.major < 2 || (glibcVersion.major == 2 && glibcVersion.minor < 29)) {
-              // This system is using an older version of glibc that does not
-              // implement FD_CLOEXEC clearing in posix_spawn_file_actions_adddup2(),
-              // so we must clear it here in the parent process.
-              try setFD_CLOEXEC(false, onFileDescriptor: fd)
-            }
+          if _slowPath(glibcVersion.major < 2 || (glibcVersion.major == 2 && glibcVersion.minor < 29)) {
+            // This system is using an older version of glibc that does not
+            // implement FD_CLOEXEC clearing in posix_spawn_file_actions_adddup2(),
+            // so we must clear it here in the parent process.
+            try setFD_CLOEXEC(false, onFileDescriptor: fd)
+          }
 #endif
 #endif
-            highestFD = max(highestFD, fd)
-          }
+          highestFD = max(highestFD, fd)
         }
       }
       func inherit(_ fileHandle: borrowing FileHandle?, as standardFD: CInt? = nil) throws {
@@ -231,20 +229,19 @@ func spawnExecutable(
   }
 #elseif os(Windows)
   return try _withStartupInfoEx(attributeCount: 1) { startupInfo in
+    @_lifetime(fileHandle)
     func inherit(_ fileHandle: borrowing FileHandle) throws -> HANDLE? {
-      try fileHandle.withUnsafeWindowsHANDLE { windowsHANDLE in
-        guard let windowsHANDLE else {
-          throw SystemError(description: "A child process cannot inherit a file handle without an associated Windows handle. Please file a bug report at https://github.com/swiftlang/swift-testing/issues/new")
-        }
-
-        // Ensure the file handle can be inherited by the child process.
-        guard SetHandleInformation(windowsHANDLE, DWORD(HANDLE_FLAG_INHERIT), DWORD(HANDLE_FLAG_INHERIT)) else {
-          throw Win32Error(rawValue: GetLastError())
-        }
-
-        return windowsHANDLE
+      guard let windowsHANDLE = fileHandle.unsafeWindowsHANDLE else {
+        throw SystemError(description: "A child process cannot inherit a file handle without an associated Windows handle. Please file a bug report at https://github.com/swiftlang/swift-testing/issues/new")
       }
+      // Ensure the file handle can be inherited by the child process.
+      guard SetHandleInformation(windowsHANDLE, DWORD(HANDLE_FLAG_INHERIT), DWORD(HANDLE_FLAG_INHERIT)) else {
+        throw Win32Error(rawValue: GetLastError())
+      }
+
+      return windowsHANDLE
     }
+    @_lifetime(fileHandle)
     func inherit(_ fileHandle: borrowing FileHandle?) throws -> HANDLE? {
       if fileHandle != nil {
         return try inherit(fileHandle!)