Update platforms and simplify example availability

Author: natecook1000

Examples/count-lines/CountLines.swift

@@ -9,11 +9,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if os(macOS)
-
 import ArgumentParser
 import Foundation
 
+@main
 struct CountLines: AsyncParsableCommand {
     @Argument(
         help: "A file to count lines in. If omitted, counts the lines of stdin.",
@@ -57,8 +56,12 @@ extension CountLines {
     }
 
     mutating func run() async throws {
+        guard #available(macOS 12, *) else {
+          print("This example isn't supported on this platform")
+          return
+        }
+      
         let countAllLines = prefix == nil
-        
         let lineCount = try await fileHandle.bytes.lines.reduce(0) { count, line in
             if countAllLines || line.starts(with: prefix!) {
                 return count + 1
@@ -70,21 +73,3 @@ extension CountLines {
         printCount(lineCount)
     }
 }
-
-#if swift(>=5.6)
-    @main extension CountLines {}
-#else
-    @main struct AsyncMain: AsyncMainProtocol {
-        typealias Command = CountLines
-    }
-#endif
-
-#else
-
-@main enum Main {
-    static func main() {
-        print("Unsupported on this platform.")
-    }
-}
-
-#endif

Package.swift

@@ -12,9 +12,9 @@
 
 import PackageDescription
 
-let package = Package(
+var package = Package(
     name: "swift-argument-parser",
-    platforms: [.macOS(.v12)],
+    platforms: [.macOS(.v10_15), .macCatalyst(.v13), .iOS(.v13), .tvOS(.v13), .watchOS(.v6)],
     products: [
         .library(
             name: "ArgumentParser",
@@ -47,15 +47,6 @@ let package = Package(
             name: "repeat",
             dependencies: ["ArgumentParser"],
             path: "Examples/repeat"),
-        .executableTarget(
-            name: "count-lines",
-            dependencies: ["ArgumentParser"],
-            path: "Examples/count-lines"),
-
-        .executableTarget(
-            name: "changelog-authors",
-            dependencies: ["ArgumentParser"],
-            path: "Tools/changelog-authors"),
 
         .testTarget(
             name: "ArgumentParserEndToEndTests",
@@ -75,3 +66,16 @@ let package = Package(
             resources: [.copy("CountLinesTest.txt")]),
     ]
 )
+
+#if swift(>=5.6)
+package.targets.append(contentsOf: [
+    .executableTarget(
+        name: "count-lines",
+        dependencies: ["ArgumentParser"],
+        path: "Examples/count-lines"),
+    .executableTarget(
+        name: "changelog-authors",
+        dependencies: ["ArgumentParser"],
+        path: "Tools/changelog-authors"),
+    ])
+#endif

Tests/ArgumentParserExampleTests/CountLinesExampleTests.swift

@@ -9,12 +9,13 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if os(macOS)
+#if os(macOS) && swift(>=5.6)
 
 import XCTest
 import ArgumentParserTestHelpers
 
 final class CountLinesExampleTests: XCTestCase {
+  @available(macOS 12, *)
   func testCountLines() throws {
     let testFile = try XCTUnwrap(Bundle.module.url(forResource: "CountLinesTest", withExtension: "txt"))
     try AssertExecuteCommand(command: "count-lines \(testFile.path)", expected: "20")

Tools/changelog-authors/ChangelogAuthors.swift

@@ -16,6 +16,8 @@ import Foundation
 
 // MARK: Command
 
+@main
+@available(macOS 12.1, *)
 struct ChangelogAuthors: AsyncParsableCommand {
   static var configuration: CommandConfiguration {
     CommandConfiguration(
@@ -101,21 +103,3 @@ struct ChangelogAuthors: AsyncParsableCommand {
     print(references(for: authors))
   }
 }
-
-#if swift(>=5.6)
-  @main extension ChangelogAuthors {}
-#else
-  @main struct AsyncMain: AsyncMainProtocol {
-    typealias Command = ChangelogAuthors
-  }
-#endif
-
-#else
-
-@main enum Main {
-    static func main() {
-        print("Unsupported on this platform.")
-    }
-}
-
-#endif