Build On Swift 6.2 (#2)

### Description

Updates certain callsites and asynchronous captures to build without
warnings or errors using Swift 6.2.

This is a source-breaking change, as it adds a few new requirements for
API users. Specifically it marks some callbacks as either `@Sendable` or
`@MainActor` which shouldn't be too large a change for most cases.

### Related Issues

*
CodeEditApp/CodeEdit#2116

### Checklist

- [x] I read and understood the [contributing
guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md)
as well as the [code of
conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots

N/A

Author: thecoolwinter

Sources/WelcomeWindow/Model/NSDocumentController+Extensions.swift

@@ -25,7 +25,7 @@ extension NSDocumentController {
     public func createFileDocumentWithDialog(
         configuration: DocumentSaveDialogConfiguration = .init(),
         onDialogPresented: @escaping () -> Void = {},
-        onCompletion: @escaping () -> Void = {},
+        onCompletion: @MainActor @escaping () -> Void = {},
         onCancel: @escaping () -> Void = {}
     ) {
         _createDocument(
@@ -53,7 +53,7 @@ extension NSDocumentController {
     public func createFolderDocumentWithDialog(
         configuration: DocumentSaveDialogConfiguration,
         onDialogPresented: @escaping () -> Void = {},
-        onCompletion: @escaping () -> Void = {},
+        onCompletion: @MainActor @escaping () -> Void = {},
         onCancel: @escaping () -> Void = {}
     ) {
         _createDocument(
@@ -100,7 +100,7 @@ extension NSDocumentController {
         mode: SaveMode,
         configuration: DocumentSaveDialogConfiguration,
         onDialogPresented: @escaping () -> Void,
-        onCompletion: @escaping () -> Void,
+        onCompletion: @MainActor @escaping () -> Void,
         onCancel: @escaping () -> Void
     ) {
         // 1 ────────────────────────────────────────────────────────────────
@@ -177,8 +177,8 @@ extension NSDocumentController {
     public func openDocumentWithDialog(
         configuration: DocumentOpenDialogConfiguration = DocumentOpenDialogConfiguration(),
         onDialogPresented: @escaping () -> Void = {},
-        onCompletion: @escaping () -> Void = {},
-        onCancel: @escaping () -> Void = {}
+        onCompletion: @MainActor @escaping () -> Void = {},
+        onCancel: @MainActor @escaping () -> Void = {}
     ) {
         let panel = NSOpenPanel()
         panel.title = configuration.title
@@ -189,12 +189,14 @@ extension NSDocumentController {
         panel.level = .modalPanel
 
         panel.begin { result in
-            guard result == .OK, let selectedURL = panel.url else {
-                onCancel()
-                return
-            }
+            DispatchQueue.mainIfNot {
+                guard result == .OK, let selectedURL = panel.url else {
+                    onCancel()
+                    return
+                }
 
-            self.openDocument(at: selectedURL, onCompletion: onCompletion, onError: { _ in onCancel() })
+                self.openDocument(at: selectedURL, onCompletion: onCompletion, onError: { _ in onCancel() })
+            }
         }
         onDialogPresented()
     }
@@ -208,25 +210,27 @@ extension NSDocumentController {
     @MainActor
     public func openDocument(
         at url: URL,
-        onCompletion: @escaping () -> Void = {},
-        onError: @escaping (Error) -> Void = { _ in }
+        onCompletion: @MainActor @escaping () -> Void = {},
+        onError: @MainActor @escaping (Error) -> Void = { _ in }
     ) {
         let accessGranted = RecentsStore.beginAccessing(url)
         openDocument(withContentsOf: url, display: true) { _, _, error in
-            if let error {
-                if accessGranted {
-                    RecentsStore.endAccessing(url)
-                }
-                DispatchQueue.main.async {
-                    NSAlert(error: error).runModal()
-                }
-                onError(error)
-            } else {
-                RecentsStore.documentOpened(at: url)
-                DispatchQueue.main.async {
-                    NSApp.activate(ignoringOtherApps: true)
+            DispatchQueue.mainIfNot {
+                if let error {
+                    if accessGranted {
+                        RecentsStore.endAccessing(url)
+                    }
+                    DispatchQueue.main.async {
+                        NSAlert(error: error).runModal()
+                    }
+                    onError(error)
+                } else {
+                    RecentsStore.documentOpened(at: url)
+                    DispatchQueue.main.async {
+                        NSApp.activate(ignoringOtherApps: true)
+                    }
+                    onCompletion()
                 }
-                onCompletion()
             }
         }
     }

Sources/WelcomeWindow/Model/RecentsStore.swift

@@ -39,7 +39,7 @@ public enum RecentsStore {
         }
     }
 
-    private static let logger = Logger(
+    private nonisolated static let logger = Logger(
         subsystem: Bundle.main.bundleIdentifier ?? "com.example.app",
         category: "RecentsStore"
     )

Sources/WelcomeWindow/Utils/DispatchQueue+asyncIfNot.swift

@@ -0,0 +1,22 @@
+//
+//  DispatchQueue+asyncIfNot.swift
+//  WelcomeWindow
+//
+//  Created by Khan Winter on 8/28/25.
+//
+
+import Foundation
+
+extension DispatchQueue {
+    /// Dispatch an operation to the main queue if it's not already on it.
+    /// - Parameter operation: The operation to enqueue.
+    static func mainIfNot(_ operation: @MainActor @escaping () -> Void) {
+        if Thread.isMainThread {
+            MainActor.assumeIsolated {
+                operation()
+            }
+        } else {
+            DispatchQueue.main.async(execute: operation)
+        }
+    }
+}

Sources/WelcomeWindow/Views/WelcomeWindow.swift

@@ -13,7 +13,7 @@ public struct WelcomeWindow<RecentsView: View, SubtitleView: View>: Scene {
 
     private let buildActions: (_ dismissWindow: @escaping () -> Void) -> WelcomeActions
     private let customRecentsList: ((_ dismissWindow: @escaping () -> Void) -> RecentsView)?
-    private let onDrop: ((_ url: URL, _ dismiss: @escaping () -> Void) -> Void)?
+    private let onDrop: (@Sendable (_ url: URL, _ dismiss: @escaping () -> Void) -> Void)?
     private let subtitleView: (() -> SubtitleView)?
     private let openHandler: WelcomeOpenHandler?
 
@@ -34,7 +34,7 @@ public struct WelcomeWindow<RecentsView: View, SubtitleView: View>: Scene {
         @ActionsBuilder actions: @escaping (_ dismissWindow: @escaping () -> Void) -> WelcomeActions,
         customRecentsList: ((_ dismissWindow: @escaping () -> Void) -> RecentsView)? = nil,
         subtitleView: (() -> SubtitleView)? = nil,
-        onDrop: ((_ url: URL, _ dismiss: @escaping () -> Void) -> Void)? = nil,
+        onDrop: (@Sendable (_ url: URL, _ dismiss: @escaping () -> Void) -> Void)? = nil,
         openHandler: WelcomeOpenHandler? = nil
     ) {
         self.iconImage = iconImage
@@ -99,7 +99,7 @@ extension WelcomeWindow where RecentsView == EmptyView, SubtitleView == EmptyVie
         iconImage: Image? = nil,
         title: String?    = nil,
         @ActionsBuilder actions: @escaping (_ dismissWindow: @escaping () -> Void) -> WelcomeActions,
-        onDrop: ((_ url: URL, _ dismissWindow: @escaping () -> Void) -> Void)? = nil,
+        onDrop: (@Sendable (_ url: URL, _ dismissWindow: @escaping () -> Void) -> Void)? = nil,
         openHandler: WelcomeOpenHandler? = nil
     ) {
         self.init(
@@ -125,7 +125,7 @@ extension WelcomeWindow where RecentsView == EmptyView {
         title: String?    = nil,
         subtitleView: @escaping () -> SubtitleView,
         @ActionsBuilder actions: @escaping (_ dismissWindow: @escaping () -> Void) -> WelcomeActions,
-        onDrop: ((_ url: URL, _ dismissWindow: @escaping () -> Void) -> Void)? = nil,
+        onDrop: (@Sendable (_ url: URL, _ dismissWindow: @escaping () -> Void) -> Void)? = nil,
         openHandler: WelcomeOpenHandler? = nil
     ) {
         self.init(
@@ -151,7 +151,7 @@ extension WelcomeWindow where SubtitleView == EmptyView {
         title: String?    = nil,
         @ActionsBuilder actions: @escaping (_ dismissWindow: @escaping () -> Void) -> WelcomeActions,
         customRecentsList: ((_ dismissWindow: @escaping () -> Void) -> RecentsView)? = nil,
-        onDrop: ((_ url: URL, _ dismissWindow: @escaping () -> Void) -> Void)? = nil,
+        onDrop: (@Sendable (_ url: URL, _ dismissWindow: @escaping () -> Void) -> Void)? = nil,
         openHandler: WelcomeOpenHandler? = nil
     ) {
         self.init(

Sources/WelcomeWindow/Views/WelcomeWindowView.swift

@@ -22,7 +22,7 @@ public struct WelcomeWindowView<RecentsView: View, SubtitleView: View>: View {
     @State private var selection: Set<URL> = []
 
     private let buildActions: (_ dismissWindow: @escaping () -> Void) -> WelcomeActions
-    private let onDrop: ((_ url: URL, _ dismiss: @escaping () -> Void) -> Void)?
+    private let onDrop: (@Sendable (_ url: URL, _ dismiss: @escaping () -> Void) -> Void)?
     private let customRecentsList: ((_ dismissWindow: @escaping () -> Void) -> RecentsView)?
     private let subtitleView: (() -> SubtitleView)?
     private let openHandler: WelcomeOpenHandler?
@@ -35,7 +35,7 @@ public struct WelcomeWindowView<RecentsView: View, SubtitleView: View>: View {
         title: String? = nil,
         subtitleView: (() -> SubtitleView)? = nil,
         buildActions: @escaping (_ dismissWindow: @escaping () -> Void) -> WelcomeActions,
-        onDrop: ((_ url: URL, _ dismiss: @escaping () -> Void) -> Void)? = nil,
+        onDrop: (@Sendable (_ url: URL, _ dismiss: @escaping () -> Void) -> Void)? = nil,
         customRecentsList: ((_ dismissWindow: @escaping () -> Void) -> RecentsView)? = nil,
         openHandler: WelcomeOpenHandler? = nil
     ) {
@@ -60,12 +60,20 @@ public struct WelcomeWindowView<RecentsView: View, SubtitleView: View>: View {
         }
     }
 
-    public var body: some View {
-        let dismiss = dismissWindow.callAsFunction
-        let actions = buildActions(dismiss)
-        let effectiveOpen = openHandler ?? defaultOpenHandler
+    var dismiss: () -> Void {
+        dismissWindow.callAsFunction
+    }
+
+    var actions: WelcomeActions {
+        buildActions(dismiss)
+    }
 
-        return HStack(spacing: 0) {
+    var effectiveOpen: (@MainActor ([URL], @escaping () -> Void) -> Void) {
+        openHandler ?? defaultOpenHandler
+    }
+
+    public var body: some View {
+        HStack(spacing: 0) {
             WelcomeView(
                 iconImage: iconImage,
                 title: title,
@@ -114,11 +122,11 @@ public struct WelcomeWindowView<RecentsView: View, SubtitleView: View>: View {
         }
         .onDrop(of: [.fileURL], isTargeted: .constant(true)) { providers in
             NSApp.activate(ignoringOtherApps: true)
-            providers.forEach {
+            providers.forEach { [onDrop, dismissWindow] in
                 _ = $0.loadDataRepresentation(for: .fileURL) { data, _ in
                     if let data, let url = URL(dataRepresentation: data, relativeTo: nil) {
                         Task { @MainActor in
-                            onDrop?(url, dismiss)
+                            onDrop?(url, dismissWindow.callAsFunction)
                         }
                     }
                 }