Improve Optional handling

Author: ktoso

Samples/JavaKitSampleApp/Package.swift

@@ -78,5 +78,16 @@ let package = Package(
         .plugin(name: "SwiftJavaPlugin", package: "swift-java"),
       ]
     ),
+    
+    .testTarget(
+      name: "JavaKitExampleTests",
+      dependencies: [
+        "JavaKitExample"
+      ],
+      swiftSettings: [
+        .swiftLanguageMode(.v5),
+        .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
+      ]
+    ),
   ]
 )

Samples/JavaKitSampleApp/Sources/JavaKitExample/com/example/swift/ThreadSafeHelperClass.java

@@ -23,14 +23,28 @@
 public class ThreadSafeHelperClass {
     public ThreadSafeHelperClass() { }
 
-    public Optional<String> text = Optional.of("");
+    public Optional<String> text = Optional.of("cool string");
 
     public final OptionalDouble val = OptionalDouble.of(2);
 
     public String getValue(Optional<String> name) {
         return name.orElse("");
     }
 
+
+    public String getOrElse(Optional<String> name) {
+        return name.orElse("or else value");
+    }
+
+    public Optional<String> getNil() {
+        return Optional.empty();
+    }
+
+    // @NonNull
+    // public Optional<String> getNil() {
+    //     return Optional.empty();
+    // }
+
     public Optional<String> getText() {
         return text;
     }

Samples/JavaKitSampleApp/Tests/JavaKitExampleTests/JavaKitOptionalTests.swift

@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+import JavaKitExample
+
+import SwiftJava
+import JavaUtilFunction
+import Testing
+
+@Suite
+struct ManglingTests {
+
+  @Test
+  func methodMangling() throws {
+    let jvm = try! JavaVirtualMachine.shared(
+      classpath: [
+        ".build/plugins/outputs/javakitsampleapp/JavaKitExample/destination/JavaCompilerPlugin/Java"
+      ]
+    )
+    let env = try! jvm.environment()
+
+    let helper = ThreadSafeHelperClass(environment: env)
+    
+    let text: JavaString? = helper.textOptional
+    #expect(#"Optional("cool string")"# == String(describing: Optional("cool string")))
+    #expect(#"Optional("cool string")"# == String(describing: text))
+
+    // let defaultValue: String? = helper.getOrElse(JavaOptional<JavaString>.empty())
+    // #expect(#"Optional("or else value")"# == String(describing: defaultValue))
+    
+    let noneValue: JavaOptional<JavaString> = helper.getNil()!
+    #expect(noneValue.isPresent() == false)
+    #expect("\(noneValue)" == "SwiftJava.JavaOptional<SwiftJava.JavaString>")
+    
+    let textFunc: JavaString? = helper.getTextOptional()
+    #expect(#"Optional("cool string")"# == String(describing: textFunc))
+    
+    let doubleOpt: Double? = helper.valOptional
+    #expect(#"Optional(2.0)"# == String(describing: doubleOpt))
+    
+    let longOpt: Int64? = helper.fromOptional(21 as Int32?)
+    #expect(#"Optional(21)"# == String(describing: longOpt))
+  }
+
+}

Samples/JavaKitSampleApp/ci-validate.sh

@@ -3,7 +3,9 @@
 set -e
 set -x
 
-swift build
+swift build \
+  --disable-experimental-prebuilts  # FIXME: until prebuilt swift-syntax isn't broken on 6.2 anymore: https://github.com/swiftlang/swift-java/issues/418
+
 "$JAVA_HOME/bin/java" \
     -cp .build/plugins/outputs/javakitsampleapp/JavaKitExample/destination/JavaCompilerPlugin/Java \
     -Djava.library.path=.build/debug \