refactor jextract plugin to be a BUILD plugin; unblocks swift 6.2

Author: ktoso

Package.swift

@@ -175,12 +175,12 @@ let package = Package(
         "JExtractSwiftPlugin"
       ]
     ),
-    .plugin(
-      name: "JExtractSwiftCommandPlugin",
-      targets: [
-        "JExtractSwiftCommandPlugin"
-      ]
-    ),
+//    .plugin(
+//      name: "JExtractSwiftCommandPlugin",
+//      targets: [
+//        "JExtractSwiftCommandPlugin"
+//      ]
+//    ),
 
     // ==== Examples
 
@@ -429,16 +429,16 @@ let package = Package(
         "SwiftJavaTool"
       ]
     ),
-    .plugin(
-      name: "JExtractSwiftCommandPlugin",
-      capability: .command(
-        intent: .custom(verb: "jextract", description: "Extract Java accessors from Swift module"),
-        permissions: [
-        ]),
-      dependencies: [
-        "SwiftJavaTool"
-      ]
-    ),
+//    .plugin(
+//      name: "JExtractSwiftCommandPlugin",
+//      capability: .command(
+//        intent: .custom(verb: "jextract", description: "Extract Java accessors from Swift module"),
+//        permissions: [
+//        ]),
+//      dependencies: [
+//        "SwiftJavaTool"
+//      ]
+//    ),
 
     .testTarget(
       name: "JavaKitTests",

Plugins/JExtractSwiftCommandPlugin/JExtractSwiftCommandPlugin.swift

@@ -72,8 +72,8 @@ final class JExtractSwiftCommandPlugin: SwiftJavaPluginProtocol, BuildToolPlugin
 
     var arguments: [String] = [
       /*subcommand=*/"jextract",
-      "--input-swift", sourceDir,
       "--swift-module", sourceModule.name,
+      "--input-swift", sourceDir,
       "--output-java", context.outputJavaDirectory.path(percentEncoded: false),
       "--output-swift", context.outputSwiftDirectory.path(percentEncoded: false),
       // TODO: "--build-cache-directory", ...

Plugins/JExtractSwiftPlugin/JExtractSwiftPlugin.swift

@@ -40,6 +40,10 @@ struct JExtractSwiftBuildToolPlugin: SwiftJavaPluginProtocol, BuildToolPlugin {
     }
 
     let sourceDir = target.directory.string
+
+    // The name of the configuration file JavaKit.config from the target for
+    // which we are generating Swift wrappers for Java classes.
+    let configFile = URL(filePath: sourceDir).appending(path: "swift-java.config")
     let configuration = try readConfiguration(sourceDir: "\(sourceDir)")
 
     guard let javaPackage = configuration?.javaPackage else {
@@ -65,18 +69,53 @@ struct JExtractSwiftBuildToolPlugin: SwiftJavaPluginProtocol, BuildToolPlugin {
       //       We'll have to make up some caching inside the tool so we don't re-parse files which have not changed etc.
     ]
     if !javaPackage.isEmpty {
-      arguments.append(contentsOf: ["--java-package", javaPackage])
+      arguments += ["--java-package", javaPackage]
+    }
+
+    let swiftFiles = sourceModule.sourceFiles.map { $0.url }.filter {
+      $0.pathExtension == "swift"
+    }
+
+    let outputSwiftFiles: [URL] = swiftFiles.compactMap { sourceFileURL in
+      guard sourceFileURL.isFileURL else {
+        return nil as URL?
+      }
+
+      let sourceFilePath = sourceFileURL.path
+      guard sourceFilePath.starts(with: sourceDir) else {
+        fatalError("Could not get relative path for source file \(sourceFilePath)")
+      }
+      var outputURL = outputSwiftDirectory
+        .appending(path: String(sourceFilePath.dropFirst(sourceDir.count).dropLast(sourceFileURL.lastPathComponent.count + 1)))
+
+      let inputFileName = sourceFileURL.deletingPathExtension().lastPathComponent
+      print(" inputFileName = \(inputFileName)")
+      let isModuleFile = inputFileName.contains("Library") // FIXME: this is a hack
+      print(" isModuleFile = \(isModuleFile)")
+
+      return if isModuleFile {
+        outputURL.appending(path: "\(inputFileName)Module+SwiftJava.swift")
+      } else {
+        outputURL.appending(path: "\(inputFileName)+SwiftJava.swift")
+      }
     }
 
     return [
-      .prebuildCommand(
+      .buildCommand(
         displayName: "Generate Java wrappers for Swift types",
         executable: toolURL,
         arguments: arguments,
-        // inputFiles: [ configFile ] + swiftFiles,
-        // outputFiles: outputJavaFiles
-        outputFilesDirectory: outputSwiftDirectory
+        inputFiles: [ configFile ] + swiftFiles,
+        outputFiles: outputSwiftFiles
       )
+//      .prebuildCommand(
+//        displayName: "Generate Java wrappers for Swift types",
+//        executable: toolURL,
+//        arguments: arguments,
+//        // inputFiles: [ configFile ] + swiftFiles,
+//        // outputFiles: outputJavaFiles
+//        outputFilesDirectory: outputSwiftDirectory
+//      )
     ]
   }
 }

Plugins/JavaCompilerPlugin/JavaCompilerPlugin.swift

@@ -34,7 +34,7 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
 
     // The name of the configuration file JavaKit.config from the target for
     // which we are generating Swift wrappers for Java classes.
-    let configFile = URL(filePath: sourceDir).appending(path: "Java2Swift.config")
+    let configFile = URL(filePath: sourceDir).appending(path: "swift-java.config")
     let config: Configuration?
 
     if let configData = try? Data(contentsOf: configFile) {
@@ -45,18 +45,21 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
 
     // The class files themselves will be generated into the build directory
     // for this target.
-    let classFiles = javaFiles.map { sourceFileURL in
+    let classFiles = javaFiles.compactMap { sourceFileURL in
+      guard sourceFileURL.isFileURL else {
+        return nil as URL?
+      }
+
       let sourceFilePath = sourceFileURL.path
       guard sourceFilePath.starts(with: sourceDir) else {
         fatalError("Could not get relative path for source file \(sourceFilePath)")
       }
 
-      return URL(
-        filePath: context.pluginWorkDirectoryURL.path
-      ).appending(path: "Java")
-       .appending(path: String(sourceFilePath.dropFirst(sourceDir.count)))
-       .deletingPathExtension()
-       .appendingPathExtension("class")
+      return URL(filePath: context.pluginWorkDirectoryURL.path)
+        .appending(path: "Java")
+        .appending(path: String(sourceFilePath.dropFirst(sourceDir.count)))
+        .deletingPathExtension()
+        .appendingPathExtension("class")
     }
 
     let javaHome = URL(filePath: findJavaHome())
@@ -73,7 +76,7 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
           "-parameters", // keep parameter names, which allows us to emit them in generated Swift decls
         ] + (config?.compilerVersionArgs ?? []),
         inputFiles: javaFiles,
-        outputFiles: classFiles
+        outputFiles: classFiles // FIXME: this is not quite enough, javac may generate more files for closures etc, which we don't know about unless we compile first
       )
     ]
   }

Plugins/SwiftJavaPlugin/SwiftJavaPlugin.swift

@@ -44,7 +44,7 @@ struct SwiftJavaBuildToolPlugin: SwiftJavaPluginProtocol, BuildToolPlugin {
     log("Config was: \(config)")
     var javaDependencies = config.dependencies ?? []
 
-    /// Find the manifest files from other Java2Swift executions in any targets
+    /// Find the manifest files from other swift-java executions in any targets
     /// this target depends on.
     var dependentConfigFiles: [(String, URL)] = []
     func searchForConfigFiles(in target: any Target) {
@@ -95,7 +95,7 @@ struct SwiftJavaBuildToolPlugin: SwiftJavaPluginProtocol, BuildToolPlugin {
     let classes = config.classes ?? [:]
     print("[swift-java-plugin] Classes to wrap (\(classes.count)): \(classes.map(\.key))")
 
-    /// Determine the set of Swift files that will be emitted by the Java2Swift tool.
+    /// Determine the set of Swift files that will be emitted by the swift-java tool.
     // TODO: this is not precise and won't work with more advanced Java files, e.g. lambdas etc.
     let outputDirectoryGenerated = self.outputDirectory(context: context, generated: true)
     let outputSwiftFiles = classes.map { (javaClassName, swiftName) in

Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/MySwiftClass.swift

@@ -0,0 +1,69 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+// This is a "plain Swift" file containing various types of declarations,
+// that is exported to Java by using the `jextract-swift` tool.
+//
+// No annotations are necessary on the Swift side to perform the export.
+
+#if os(Linux)
+import Glibc
+#else
+import Darwin.C
+#endif
+
+public class MySwiftClass {
+
+  public var len: Int
+  public var cap: Int
+
+  public init(len: Int, cap: Int) {
+    self.len = len
+    self.cap = cap
+
+    p("\(MySwiftClass.self).len = \(self.len)")
+    p("\(MySwiftClass.self).cap = \(self.cap)")
+    let addr = unsafeBitCast(self, to: UInt64.self)
+    p("initializer done, self = 0x\(String(addr, radix: 16, uppercase: true))")
+  }
+
+  deinit {
+    let addr = unsafeBitCast(self, to: UInt64.self)
+    p("Deinit, self = 0x\(String(addr, radix: 16, uppercase: true))")
+  }
+
+  public var counter: Int32 = 0
+
+  public func voidMethod() {
+    p("")
+  }
+
+  public func takeIntMethod(i: Int) {
+    p("i:\(i)")
+  }
+
+  public func echoIntMethod(i: Int) -> Int {
+    p("i:\(i)")
+    return i
+  }
+
+  public func makeIntMethod() -> Int {
+    p("make int -> 12")
+    return 12
+  }
+
+  public func makeRandomIntMethod() -> Int {
+    return Int.random(in: 1..<256)
+  }
+}

Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/MySwiftLibrary.swift

@@ -38,55 +38,55 @@ public func globalTakeIntInt(i: Int, j: Int) {
 public func globalCallMeRunnable(run: () -> ()) {
   run()
 }
-
-public class MySwiftClass {
-
-  public var len: Int
-  public var cap: Int
-
-  public init(len: Int, cap: Int) {
-    self.len = len
-    self.cap = cap
-
-    p("\(MySwiftClass.self).len = \(self.len)")
-    p("\(MySwiftClass.self).cap = \(self.cap)")
-    let addr = unsafeBitCast(self, to: UInt64.self)
-    p("initializer done, self = 0x\(String(addr, radix: 16, uppercase: true))")
-  }
-
-  deinit {
-    let addr = unsafeBitCast(self, to: UInt64.self)
-    p("Deinit, self = 0x\(String(addr, radix: 16, uppercase: true))")
-  }
-
-  public var counter: Int32 = 0
-
-  public func voidMethod() {
-    p("")
-  }
-
-  public func takeIntMethod(i: Int) {
-    p("i:\(i)")
-  }
-
-  public func echoIntMethod(i: Int) -> Int {
-    p("i:\(i)")
-    return i
-  }
-
-  public func makeIntMethod() -> Int {
-    p("make int -> 12")
-    return 12
-  }
-
-  public func makeRandomIntMethod() -> Int {
-    return Int.random(in: 1..<256)
-  }
-}
+//
+//public class MySwiftClass {
+//
+//  public var len: Int
+//  public var cap: Int
+//
+//  public init(len: Int, cap: Int) {
+//    self.len = len
+//    self.cap = cap
+//
+//    p("\(MySwiftClass.self).len = \(self.len)")
+//    p("\(MySwiftClass.self).cap = \(self.cap)")
+//    let addr = unsafeBitCast(self, to: UInt64.self)
+//    p("initializer done, self = 0x\(String(addr, radix: 16, uppercase: true))")
+//  }
+//
+//  deinit {
+//    let addr = unsafeBitCast(self, to: UInt64.self)
+//    p("Deinit, self = 0x\(String(addr, radix: 16, uppercase: true))")
+//  }
+//
+//  public var counter: Int32 = 0
+//
+//  public func voidMethod() {
+//    p("")
+//  }
+//
+//  public func takeIntMethod(i: Int) {
+//    p("i:\(i)")
+//  }
+//
+//  public func echoIntMethod(i: Int) -> Int {
+//    p("i:\(i)")
+//    return i
+//  }
+//
+//  public func makeIntMethod() -> Int {
+//    p("make int -> 12")
+//    return 12
+//  }
+//
+//  public func makeRandomIntMethod() -> Int {
+//    return Int.random(in: 1..<256)
+//  }
+//}
 
 // ==== Internal helpers
 
-private func p(_ msg: String, file: String = #fileID, line: UInt = #line, function: String = #function) {
+func p(_ msg: String, file: String = #fileID, line: UInt = #line, function: String = #function) {
   print("[swift][\(file):\(line)](\(function)) \(msg)")
   fflush(stdout)
 }