Handling unsigned numbers better in jextract

.unacceptablelanguageignore

@@ -3,4 +3,5 @@ Sources/_Subprocess/Platforms/Subprocess+Darwin.swift
 Sources/_Subprocess/Platforms/Subprocess+Linux.swift
 Sources/_Subprocess/Platforms/Subprocess+Unix.swift
 Sources/_Subprocess/Teardown.swift
-Sources/_Subprocess/Subprocess.swift
+Sources/_Subprocess/Subprocess.swift
+NOTICE.txt

Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/MySwiftLibrary.swift

@@ -45,6 +45,11 @@ public func globalTakeIntInt(i: Int64, j: Int64) {
   p("i:\(i), j:\(j)")
 }
 
+public func echoUnsignedInt(i: UInt32, j: UInt64) -> UInt64 {
+  p("i:\(i), j:\(j)")
+  return UInt64(i) + j
+}
+
 // ==== Internal helpers
 
 func p(_ msg: String, file: String = #fileID, line: UInt = #line, function: String = #function) {

Samples/JExtractJNISampleApp/src/test/java/com/example/swift/MySwiftLibraryTest.java

@@ -61,4 +61,11 @@ void globalVariable() {
         MySwiftLibrary.setGlobalVariable(100);
         assertEquals(100, MySwiftLibrary.getGlobalVariable());
     }
+
+    @Test
+    void globalUnsignedIntEcho() {
+        int i = 12;
+        long l = 1200;
+        assertEquals(1212, MySwiftLibrary.echoUnsignedInt(12, 1200));
+    }
 }

Samples/SwiftKitSampleApp/Sources/MySwiftLibrary/MySwiftClass.swift

@@ -60,4 +60,16 @@ public class MySwiftClass {
   public func makeRandomIntMethod() -> Int {
     return Int.random(in: 1..<256)
   }
+
+  public func takeUnsignedChar(arg: UInt16) {
+    p("\(UInt32.self) = \(arg)")
+  }
+
+  public func takeUnsignedInt(arg: UInt32) {
+    p("\(UInt32.self) = \(arg)")
+  }
+
+  public func takeUnsignedLong(arg: UInt64) {
+    p("\(UInt64.self) = \(arg)")
+  }
 }

Samples/SwiftKitSampleApp/src/test/java/com/example/swift/UnsignedNumbersTest.java

@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 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
+//
+//===----------------------------------------------------------------------===//
+
+package com.example.swift;
+
+import org.junit.jupiter.api.Test;
+import org.swift.swiftkit.ffm.AllocatingSwiftArena;
+
+public class UnsignedNumbersTest {
+    @Test
+    void take_uint32() {
+        try (var arena = AllocatingSwiftArena.ofConfined()) {
+            var c = MySwiftClass.init(1, 2, arena);
+            c.takeUnsignedInt(128);
+        }
+    }
+
+    @Test
+    void take_uint64() {
+        try (var arena = AllocatingSwiftArena.ofConfined()) {
+            var c = MySwiftClass.init(1, 2, arena);
+            c.takeUnsignedLong(Long.MAX_VALUE);
+        }
+    }
+}

Sources/JExtractSwiftLib/Common/TypeAnnotations.swift

@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 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 JavaTypes
+import JavaKitConfigurationShared
+
+/// Determine if the given type needs any extra annotations that should be included
+/// in Java sources when the corresponding Java type is rendered.
+func getTypeAnnotations(swiftType: SwiftType, config: Configuration) -> [JavaAnnotation] {
+  if swiftType.isUnsignedInteger, config.effectiveUnsignedNumbersMode == .annotate {
+    return [JavaAnnotation.unsigned]
+  }
+
+  return []
+}

Sources/JExtractSwiftLib/Configuration+Extensions.swift

@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 JavaKitConfigurationShared // TODO: this should become SwiftJavaConfigurationShared
+import JavaTypes // TODO: this should become SwiftJavaConfigurationShared
+
+extension Configuration {
+  public var effectiveUnsignedNumericsMode: UnsignedNumericsMode {
+    switch effectiveUnsignedNumbersMode {
+    case .annotate: .ignoreSign
+    case .wrapGuava: .wrapUnsignedGuava
+    }
+  }
+}

Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -105,9 +105,16 @@ extension FFMSwift2JavaGenerator {
     var params: [String] = []
     var args: [String] = []
     for param in cFunc.parameters {
-      // ! unwrapping because cdecl lowering guarantees the parameter named.
-      params.append("\(param.type.javaType) \(param.name!)")
-      args.append(param.name!)
+      let name = param.name! // !-safe, because cdecl lowering guarantees the parameter named.
+
+      let annotationsStr =
+        if param.type.javaType.parameterAnnotations.isEmpty {
+          ""
+        } else {
+          param.type.javaType.parameterAnnotations.map({$0.render()}).joined(separator: " ") + " "
+        }
+      params.append("\(annotationsStr)\(param.type.javaType) \(name)")
+      args.append(name)
     }
     let paramsStr = params.joined(separator: ", ")
     let argsStr = args.joined(separator: ", ")
@@ -316,23 +323,21 @@ extension FFMSwift2JavaGenerator {
     let translatedSignature = translated.translatedSignature
     let returnTy = translatedSignature.result.javaResultType
 
+    var annotationsStr = translatedSignature.annotations.map({ $0.render() }).joined(separator: "\n")
+    if !annotationsStr.isEmpty { annotationsStr += "\n" }
+
     var paramDecls = translatedSignature.parameters
       .flatMap(\.javaParameters)
-      .map { "\($0.type) \($0.name)" }
+      .map { $0.renderParameter() }
     if translatedSignature.requiresSwiftArena {
       paramDecls.append("AllocatingSwiftArena swiftArena$")
     }
 
     // TODO: we could copy the Swift method's documentation over here, that'd be great UX
+    printDeclDocumentation(&printer, decl)
     printer.printBraceBlock(
       """
-      /**
-       * Downcall to Swift:
-       * {@snippet lang=swift :
-       * \(decl.signatureString)
-       * }
-       */
-      \(modifiers) \(returnTy) \(methodName)(\(paramDecls.joined(separator: ", ")))
+      \(annotationsStr)\(modifiers) \(returnTy) \(methodName)(\(paramDecls.joined(separator: ", ")))
       """
     ) { printer in
       if case .instance(_) =  decl.functionSignature.selfParameter {
@@ -344,6 +349,19 @@ extension FFMSwift2JavaGenerator {
     }
   }
 
+  private func printDeclDocumentation(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
+    printer.print(
+      """
+      /**
+       * Downcall to Swift:
+       * {@snippet lang=swift :
+       * \(decl.signatureString)
+       * }
+       */
+      """
+    )
+  }
+
   /// Print the actual downcall to the Swift API.
   ///
   /// This assumes that all the parameters are passed-in with appropriate names.