Make the entry point async. This is somewhat preliminary, since I'm trying to find a way to do this without requiring macOS 12 for any use of plugins.

Author: abertelrud

Sources/PackagePlugin/Implementation.swift

@@ -27,7 +27,7 @@
 
 extension Plugin {
 
-    public static func main() throws {
+    public static func main() async throws {
         // Look for the input JSON as the last argument of the invocation.
         guard let inputData = ProcessInfo.processInfo.arguments.last?.data(using: .utf8) else {
             fputs("Expected last argument to contain JSON input data in UTF-8 encoding, but didn't find it.", stderr)
@@ -57,7 +57,7 @@ extension Plugin {
             guard let plugin = plugin as? BuildToolPlugin else {
                 throw PluginDeserializationError.malformedInputJSON("Plugin declared with `buildTool` capability but doesn't conform to `BuildToolPlugin` protocol")
             }
-            let commands = try plugin.createBuildCommands(context: context)
+            let commands = try await plugin.createBuildCommands(context: context)
 
             // Convert the commands to the encodable output representation SwiftPM currently expects.
             output.buildCommands = commands.compactMap {

Sources/PackagePlugin/PublicAPI/Protocols.swift

@@ -31,5 +31,5 @@ public protocol BuildToolPlugin: Plugin {
     /// commands, configured based on the information in the context.
     func createBuildCommands(
         context: TargetBuildContext
-    ) throws -> [Command]
+    ) async throws -> [Command]
 }