Adopt Swift 6 language mode

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ on:
 
 jobs:
   test:
-    runs-on: macos-14
+    runs-on: macos-latest
 
     steps:
       - uses: actions/checkout@v7
@@ -31,7 +31,7 @@ jobs:
       - run: swift test -v
 
   build:
-    runs-on: macos-14
+    runs-on: macos-latest
     needs: [test]
 
     steps:

.swift-version

@@ -1 +1 @@
-5.10
+6.3.3

AGENTS.md

@@ -6,6 +6,14 @@ asynchronously (via `NSWorkspace.recycle`).
 - `Sources/Trash/Trash.swift` — the entire app. `Trash.put` spins
   `CFRunLoopRun()`/`CFRunLoopStop` to block on `NSWorkspace.recycle`'s
   async-only completion handler — don't "simplify" this into an early return.
+  The `nonisolated(unsafe)` on `Trash.put`'s local `error` and on
+  `CLI.standardError` is safe, not dead code: `error` is only ever written
+  from inside the completion handler and only ever read after
+  `CFRunLoopRun()` returns, which the run loop guarantees happens after
+  that write; `standardError` is assigned once at startup and only ever
+  touched from `CLI.main()`'s single thread. Don't remove either
+  annotation — Swift 6 strict concurrency checking will fail to compile
+  without them.
 - `Tests/TrashTests/TrashTests.swift` — XCTest suite.
 
 ## Build / test / run

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.7.3
+// swift-tools-version:6.3.3
 
 import PackageDescription
 

Sources/Trash/Trash.swift

@@ -8,7 +8,7 @@ Usage: trash [file ...]
 
 public struct Trash {
     public static func put(_ paths: [String]) throws {
-        var error: NSError?
+        nonisolated(unsafe) var error: NSError?
         let urls = paths.map(URL.init(fileURLWithPath:))
         let loop = CFRunLoopGetCurrent()
 
@@ -35,7 +35,7 @@ extension FileHandle: TextOutputStream {
 
 @main
 struct CLI {
-    static var standardError = FileHandle.standardError
+    nonisolated(unsafe) static var standardError = FileHandle.standardError
 
     static func main() {
         let args = Array(CommandLine.arguments.dropFirst())