Tweak AsyncParsableCommand to support 5.5/5.6

Author: natecook1000

Sources/ArgumentParser/CMakeLists.txt

@@ -13,6 +13,7 @@ add_library(ArgumentParser
   "Parsable Properties/Option.swift"
   "Parsable Properties/OptionGroup.swift"
 
+  "Parsable Types/AsyncParsableCommand.swift"
   "Parsable Types/CommandConfiguration.swift"
   "Parsable Types/EnumerableFlag.swift"
   "Parsable Types/ExpressibleByArgument.swift"

Sources/ArgumentParser/Parsable Types/AsyncParsableCommand.swift

@@ -15,21 +15,34 @@ public protocol AsyncParsableCommand: ParsableCommand {
 }
 
 extension AsyncParsableCommand {
-  public mutating func run() throws {
-    throw CleanExit.helpRequest(self)
+  public static func main() async {
+    do {
+      var command = try parseAsRoot()
+      if var asyncCommand = command as? AsyncParsableCommand {
+        try await asyncCommand.run()
+      } else {
+        try command.run()
+      }
+    } catch {
+      exit(withError: error)
+    }
   }
 }
 
-public protocol AsyncMain {
+@available(
+  swift, deprecated: 5.6,
+  message: "Use @main directly on your root `AsyncParsableCommand` type.")
+public protocol AsyncMainProtocol {
   associatedtype Command: ParsableCommand
 }
 
-extension AsyncMain {
+@available(swift, deprecated: 5.6)
+extension AsyncMainProtocol {
   public static func main() async {
     do {
       var command = try Command.parseAsRoot()
-      if var command = command as? AsyncParsableCommand {
-        try await command.run()
+      if var asyncCommand = command as? AsyncParsableCommand {
+        try await asyncCommand.run()
       } else {
         try command.run()
       }
@@ -38,3 +51,4 @@ extension AsyncMain {
     }
   }
 }
+

Tools/changelog-authors/ChangelogAuthors.swift

@@ -100,6 +100,10 @@ struct ChangelogAuthors: AsyncParsableCommand {
   }
 }
 
-@main enum Main: AsyncMain {
-  typealias Command = ChangelogAuthors
-}
+#if swift(>=5.6)
+  @main extension ChangelogAuthors {}
+#else
+  @main struct AsyncMain: AsyncMainProtocol {
+    typealias Command = ChangelogAuthors
+  }
+#endif