JavaKit: add source/target versions to Java2Swift.config

Plugins/Java2SwiftPlugin/Configuration.swift

@@ -12,6 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+typealias JavaVersion = Int
+
 /// Configuration for the Java2Swift translation tool, provided on a per-target
 /// basis.
 ///
@@ -25,4 +27,10 @@ struct Configuration: Codable {
   /// canonical Java class names (e.g., java.util.Vector) and the values are
   /// the corresponding Swift names (e.g., JavaVector).
   var classes: [String: String] = [:]
+
+  // Compile for the specified Java SE release.
+  var sourceCompatibility: JavaVersion?
+
+  // Generate class files suitable for the specified Java SE release.
+  var targetCompatibility: JavaVersion?
 }

Plugins/JavaCompilerPlugin/Configuration.swift

@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+typealias JavaVersion = Int
+
+/// Configuration for the Java2Swift translation tool, provided on a per-target
+/// basis.
+///
+/// Note: there is a copy of this struct in the Java2Swift library. They
+/// must be kept in sync.
+struct Configuration: Codable {
+  /// The Java class path that should be passed along to the Java2Swift tool.
+  var classPath: String? = nil
+
+  /// The Java classes that should be translated to Swift. The keys are
+  /// canonical Java class names (e.g., java.util.Vector) and the values are
+  /// the corresponding Swift names (e.g., JavaVector).
+  var classes: [String: String] = [:]
+
+  // Compile for the specified Java SE release.
+  var sourceCompatibility: JavaVersion?
+
+  // Generate class files suitable for the specified Java SE release.
+  var targetCompatibility: JavaVersion?
+}
+
+extension Configuration {
+  var compilerVersionArgs: [String] {
+    var compilerVersionArgs = [String]()
+
+    if let sourceCompatibility {
+      compilerVersionArgs += ["--source", String(sourceCompatibility)]
+    }
+    if let targetCompatibility {
+      compilerVersionArgs += ["--target", String(targetCompatibility)]
+    }
+
+    return compilerVersionArgs
+  }
+}

Plugins/JavaCompilerPlugin/JavaCompilerPlugin.swift

@@ -32,6 +32,17 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
     // so we cannot eliminate this deprecation warning.
     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: "Java2Swift.config")
+    let config: Configuration?
+
+    if let configData = try? Data(contentsOf: configFile) {
+      config = try? JSONDecoder().decode(Configuration.self, from: configData)
+    } else {
+      config = nil
+    }
+
     // The class files themselves will be generated into the build directory
     // for this target.
     let classFiles = javaFiles.map { sourceFileURL in
@@ -60,7 +71,7 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
         arguments: javaFiles.map { $0.path(percentEncoded: false) } + [
           "-d", javaClassFileURL.path(),
           "-parameters", // keep parameter names, which allows us to emit them in generated Swift decls
-        ],
+        ] + (config?.compilerVersionArgs ?? []),
         inputFiles: javaFiles,
         outputFiles: classFiles
       )

Sources/Java2SwiftLib/Configuration.swift

@@ -12,6 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+package typealias JavaVersion = Int
+
 /// Configuration for the Java2Swift translation tool, provided on a per-target
 /// basis.
 ///
@@ -26,8 +28,18 @@ package struct Configuration: Codable {
   /// the corresponding Swift names (e.g., JavaVector).
   package var classes: [String: String] = [:]
 
-  package init(classPath: String? = nil, classes: [String : String] = [:]) {
+  package var sourceCompatibility: JavaVersion?
+  package var targetCompatibility: JavaVersion?
+
+  package init(
+    classPath: String? = nil,
+    classes: [String : String] = [:],
+    sourceCompatibility: JavaVersion? = nil,
+    targetCompatibility: JavaVersion? = nil
+  ) {
     self.classPath = classPath
     self.classes = classes
+    self.sourceCompatibility = sourceCompatibility
+    self.targetCompatibility = targetCompatibility
   }
 }