Some minor frontend tweaks.

- Switch to `@main` on the top-level command.
- Move the function that prints the version information into its
  own file, so it can be swapped out with something else for
  custom builds. (It would be nice to automate this similar to
  what swift-testing is doing with their GitPlugin, but I don't
  want to steal that code verbatim just yet.)
- Make the version string on the main branch "main" instead of
  an older value that just happened to stick around. In the
  future, this should always be "main" and it can be updated on
  the actual release branches (or automated ideally).

Author: allevato

Sources/swift-format/PrintVersion.swift

@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+func printVersionInformation() {
+  // TODO: Automate updates to this somehow.
+  print("main")
+}

Sources/swift-format/main.swift renamed to Sources/swift-format/SwiftFormatCommand.swift

@@ -14,6 +14,7 @@ import ArgumentParser
 
 /// Collects the command line options that were passed to `swift-format` and dispatches to the
 /// appropriate subcommand.
+@main
 struct SwiftFormatCommand: ParsableCommand {
   static var configuration = CommandConfiguration(
     commandName: "swift-format",
@@ -29,5 +30,3 @@ struct SwiftFormatCommand: ParsableCommand {
   @OptionGroup()
   var versionOptions: VersionOptions
 }
-
-SwiftFormatCommand.main()

Sources/swift-format/VersionOptions.swift

@@ -19,8 +19,7 @@ struct VersionOptions: ParsableArguments {
 
   func validate() throws {
     if version {
-      // TODO: Automate updates to this somehow.
-      print("508.0.0")
+      printVersionInformation()
       throw ExitCode.success
     }
   }