Swift plugin target sourceFiles do not include generated files

[doozMen]

Description

I have a plugin that generates a swift file on build via a plugin. In another target in the same package I would like to use that file as input. However I notice that the sourcefiles on the target do not include generated source files in the pluginWorkingDirectory?

Inside my plugin I have the following:

import Foundation
import PackagePlugin

enum Error: Swift.Error {
  case missingAssetSwiftFile
  case missingUIComponents
}

@main
struct ReuseGenerated: BuildToolPlugin {

  func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {

    print("📦 reuse generated started")
    guard let uiComponents = try context.package.targets(named: ["UIComponents"]).first as? SwiftSourceModuleTarget else {
      throw Error.missingUIComponents
    }
    print("Did find files in UIComponents")

    print(uiComponents.sourceFiles.map { $0.path.string}.joined(separator: "\n"))

    print("---")

    guard let swiftAssetFile = (uiComponents.sourceFiles.first { $0.path.lastComponent == "Assets.swift"}) else {
      throw Error.missingAssetSwiftFile
    }

    let output = context.pluginWorkDirectory.appending("Assets.swift")

    return [
      .prebuildCommand(
        displayName: "📦 Generate new content based on generated source code of other target",
        executable: .init("/usr/bin/touch"),
        arguments: [output.string],
        outputFilesDirectory: context.pluginWorkDirectory)
    ]
  }

}

Expected behavior

I would expect the file generated before to be there, or the docs telling me that sourceFiles only include non generated files

Actual behavior

It is not there

Steps to reproduce

I have created a sample project reporduces the issue when building lib Foo doozMen/swift-generated-asset-plugin: Shows how to generate an asset catalog that can load colors into a SwiftUI view from the plugin working directory

Swift Package Manager version/commit hash

releases with xcode 14.3 beta 2

Swift & OS version (output of swift --version && uname -a)

swift-driver version: 1.75.1 Apple Swift version 5.8 (swiftlang-5.8.0.119.11 clang-1403.0.22.11.100)
Target: arm64-apple-macosx13.0
Darwin stijns-mac.lan 22.3.0 Darwin Kernel Version 22.3.0: Mon Jan 30 20:38:37 PST 2023; root:xnu-8792.81.3~2/RELEASE_ARM64_T6000 arm64