Correct how we find JavaStdlib/ in swiftpm plugin for wrap-java

Author: ktoso

Plugins/PluginsShared/SwiftJavaPluginProtocol.swift

@@ -23,4 +23,8 @@ extension SwiftJavaPluginProtocol {
   func log(_ message: @autoclosure () -> String, terminator: String = "\n") {
     print("[\(pluginName)] \(message())", terminator: terminator)
   }
+  
+  func warn(_ message: @autoclosure () -> String, terminator: String = "\n") {
+    print("[\(pluginName)][warning] \(message())", terminator: terminator)
+  }
 }

Plugins/SwiftJavaPlugin/SwiftJavaPlugin.swift

@@ -242,30 +242,34 @@ extension SwiftJavaBuildToolPlugin {
   func outputFilePath(context: PluginContext, generated: Bool, filename: String) -> URL {
     outputDirectory(context: context, generated: generated).appending(path: filename)
   }
-}
-
-func getExtractedJavaStdlibModules() -> [String] {
-  let fileManager = FileManager.default
-  let sourcesPath = URL(fileURLWithPath: #filePath)
-    .deletingLastPathComponent()
-    .deletingLastPathComponent()
-    .appendingPathComponent("Sources")
-    .appendingPathComponent("JavaStdlib")
-
-  guard let stdlibDirContents = try? fileManager.contentsOfDirectory(
-    at: sourcesPath,
-    includingPropertiesForKeys: [.isDirectoryKey],
-    options: [.skipsHiddenFiles]
-  ) else {
-    return []
-  }
 
-  return stdlibDirContents.compactMap { url in
-    guard let resourceValues = try? url.resourceValues(forKeys: [.isDirectoryKey]),
-          let isDirectory = resourceValues.isDirectory,
-          isDirectory else {
-      return nil
+  func getExtractedJavaStdlibModules() -> [String] {
+    let fileManager = FileManager.default
+    log("Search for JavaStdlib inside: \(#filePath)")
+    let sourcesPath = URL(fileURLWithPath: #filePath)
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .appendingPathComponent("Sources")
+      .appendingPathComponent("JavaStdlib")
+
+    guard let stdlibDirContents = try? fileManager.contentsOfDirectory(
+      at: sourcesPath,
+      includingPropertiesForKeys: [.isDirectoryKey],
+      options: [.skipsHiddenFiles]
+    ) else {
+      warn("Unable to find Java standard library Swift wrappers! Expected \(sourcesPath) to exist." + 
+           "May be unable to wrap-java types involving Java standard library types.")
+      return []
     }
-    return url.lastPathComponent
-  }.sorted()
+
+    return stdlibDirContents.compactMap { url in
+      guard let resourceValues = try? url.resourceValues(forKeys: [.isDirectoryKey]),
+            let isDirectory = resourceValues.isDirectory,
+            isDirectory else {
+        return nil
+      }
+      return url.lastPathComponent
+    }.sorted()
+  }
 }