[JExtract/JNI] Add support for protocols as parameter types (swiftlang#376)

Author: madsodgaard

Samples/SwiftJavaExtractJNISampleApp/Sources/MySwiftLibrary/ConcreteProtocolAB.swift

@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+public class ConcreteProtocolAB: ProtocolA, ProtocolB {
+  public let constantA: Int64
+  public let constantB: Int64
+  public var mutable: Int64 = 0
+
+  public func name() -> String {
+    return "ConcreteProtocolAB"
+  }
+
+  public init(constantA: Int64, constantB: Int64) {
+    self.constantA = constantA
+    self.constantB = constantB
+  }
+}

Samples/SwiftJavaExtractJNISampleApp/Sources/MySwiftLibrary/ProtocolA.swift

@@ -0,0 +1,24 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+public protocol ProtocolA {
+  var constantA: Int64 { get }
+  var mutable: Int64 { get set }
+
+  func name() -> String
+}
+
+public func takeProtocol(_ proto1: any ProtocolA, _ proto2: some ProtocolA) -> Int64 {
+  return proto1.constantA + proto2.constantA
+}

Samples/SwiftJavaExtractJNISampleApp/Sources/MySwiftLibrary/ProtocolB.swift

@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+public protocol ProtocolB {
+  var constantB: Int64 { get }
+}
+
+public func takeCombinedProtocol(_ proto: some ProtocolA & ProtocolB) -> Int64 {
+  return proto.constantA + proto.constantB
+}
+
+public func takeGenericProtocol<First: ProtocolA, Second: ProtocolB>(_ proto1: First, _ proto2: Second) -> Int64 {
+  return proto1.constantA + proto2.constantB
+}
+
+public func takeCombinedGenericProtocol<T: ProtocolA & ProtocolB>(_ proto: T) -> Int64 {
+  return proto.constantA + proto.constantB
+}

Samples/JExtractJNISampleApp/src/jmh/java/com/example/swift/EnumBenchmark.java renamed to Samples/SwiftJavaExtractJNISampleApp/src/jmh/java/com/example/swift/EnumBenchmark.java

@@ -16,6 +16,7 @@
 
 import org.junit.jupiter.api.Test;
 import org.swift.swiftkit.core.ConfinedSwiftMemorySession;
+import org.swift.swiftkit.core.JNISwiftInstance;
 import org.swift.swiftkit.core.SwiftArena;
 
 import java.util.Optional;

Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/AlignmentEnumTest.java

@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+package com.example.swift;
+
+import org.junit.jupiter.api.Test;
+import org.swift.swiftkit.core.SwiftArena;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class ProtocolTest {
+    @Test
+    void takeProtocol() {
+        try (var arena = SwiftArena.ofConfined()) {
+            ConcreteProtocolAB proto1 = ConcreteProtocolAB.init(10, 5, arena);
+            ConcreteProtocolAB proto2 = ConcreteProtocolAB.init(20, 1, arena);
+            assertEquals(30, MySwiftLibrary.takeProtocol(proto1, proto2));
+        }
+    }
+
+    @Test
+    void takeCombinedProtocol() {
+        try (var arena = SwiftArena.ofConfined()) {
+            ConcreteProtocolAB proto1 = ConcreteProtocolAB.init(10, 5, arena);
+            assertEquals(15, MySwiftLibrary.takeCombinedProtocol(proto1));
+        }
+    }
+
+    @Test
+    void takeGenericProtocol() {
+        try (var arena = SwiftArena.ofConfined()) {
+            ConcreteProtocolAB proto1 = ConcreteProtocolAB.init(10, 5, arena);
+            ConcreteProtocolAB proto2 = ConcreteProtocolAB.init(20, 1, arena);
+            assertEquals(11, MySwiftLibrary.takeGenericProtocol(proto1, proto2));
+        }
+    }
+
+    @Test
+    void takeCombinedGenericProtocol() {
+        try (var arena = SwiftArena.ofConfined()) {
+            ConcreteProtocolAB proto1 = ConcreteProtocolAB.init(10, 5, arena);
+            assertEquals(15, MySwiftLibrary.takeCombinedGenericProtocol(proto1));
+        }
+    }
+
+    @Test
+    void protocolVariables() {
+        try (var arena = SwiftArena.ofConfined()) {
+            ProtocolA proto1 = ConcreteProtocolAB.init(10, 5, arena);
+            assertEquals(10, proto1.getConstantA());
+            assertEquals(0, proto1.getMutable());
+            proto1.setMutable(3);
+            assertEquals(3, proto1.getMutable());
+        }
+    }
+
+    @Test
+    void protocolMethod() {
+        try (var arena = SwiftArena.ofConfined()) {
+            ProtocolA proto1 = ConcreteProtocolAB.init(10, 5, arena);
+            assertEquals("ConcreteProtocolAB", proto1.name());
+        }
+    }
+}

Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/ProtocolTest.java

@@ -95,7 +95,11 @@ extension DeclModifierSyntax {
 }
 
 extension WithModifiersSyntax {
-  var isPublic: Bool {
+  func isPublic(in type: NominalTypeDeclSyntaxNode?) -> Bool {
+    if let type, case .protocolDecl(let protocolDecl) = Syntax(type).as(SyntaxEnum.self) {
+      return protocolDecl.isPublic(in: nil)
+    }
+
     return self.modifiers.contains { modifier in
       modifier.isPublic
     }

Sources/JExtractSwiftLib/Convenience/SwiftSyntax+Extensions.swift

@@ -68,7 +68,7 @@ extension CType {
     case .optional(let wrapped) where wrapped.isPointer:
       try self.init(cdeclType: wrapped)
 
-    case .genericParameter, .metatype, .optional, .tuple, .opaque, .existential:
+    case .genericParameter, .metatype, .optional, .tuple, .opaque, .existential, .composite:
       throw CDeclToCLoweringError.invalidCDeclType(cdeclType)
     }
   }

Sources/JExtractSwiftLib/FFM/CDeclLowering/CRepresentation.swift

@@ -344,6 +344,9 @@ struct CdeclLowering {
 
     case .optional(let wrapped):
       return try lowerOptionalParameter(wrapped, convention: convention, parameterName: parameterName, genericParameters: genericParameters, genericRequirements: genericRequirements)
+
+    case .composite:
+      throw LoweringError.unhandledType(type)
     }
   }
 
@@ -412,7 +415,7 @@ struct CdeclLowering {
       }
       throw LoweringError.unhandledType(.optional(wrappedType))
 
-    case .function, .metatype, .optional:
+    case .function, .metatype, .optional, .composite:
       throw LoweringError.unhandledType(.optional(wrappedType))
     }
   }
@@ -513,7 +516,7 @@ struct CdeclLowering {
       // Custom types are not supported yet.
       throw LoweringError.unhandledType(type)
 
-    case .genericParameter, .function, .metatype, .optional, .tuple, .existential, .opaque:
+    case .genericParameter, .function, .metatype, .optional, .tuple, .existential, .opaque, .composite:
       // TODO: Implement
       throw LoweringError.unhandledType(type)
     }
@@ -667,7 +670,7 @@ struct CdeclLowering {
         conversion: .tupleExplode(conversions, name: outParameterName)
       )
 
-    case .genericParameter, .function, .optional, .existential, .opaque:
+    case .genericParameter, .function, .optional, .existential, .opaque, .composite:
       throw LoweringError.unhandledType(type)
     }
   }

Sources/JExtractSwiftLib/FFM/CDeclLowering/FFMSwift2JavaGenerator+FunctionLowering.swift

@@ -396,9 +396,12 @@ extension FFMSwift2JavaGenerator {
 
     // Indirect return receivers.
     for outParameter in translatedSignature.result.outParameters {
-      let memoryLayout = renderMemoryLayoutValue(for: outParameter.type)
+      guard case .concrete(let type) = outParameter.type else {
+        continue
+      }
+      let memoryLayout = renderMemoryLayoutValue(for: type)
 
-      let arena = if let className = outParameter.type.className,
+      let arena = if let className = type.className,
          analysis.importedTypes[className] != nil {
         // Use passed-in 'SwiftArena' for 'SwiftValue'.
         "swiftArena$"