jextract: Indirect returns and more value type support (#211)

* ignore .index-build directory

* Implement SwiftValue cleanup

* SourceGen: Handle init() of value types with indirect return

* Followups for handling value inits, various helper funcs

* SwiftArena is now a segment allocator

* Add $destroyed flag to wrapper types to prevent use-after-free bugs

* Use varHandle instead of offset for reading data off VWT

* testing: skip empty lines in output matching

* gitignore vscode build outputs

* test fixups

* more tests for protecting access to destroyed objects

* remove commented out code

* fix formatting

Author: ktoso

.gitignore

@@ -11,6 +11,8 @@ DerivedData/
 *.class
 bin/
 BuildLogic/out/
+.index-build
+.build-vscode
 
 # Ignore gradle build artifacts
 .gradle

Samples/SwiftKitSampleApp/Sources/MySwiftLibrary/MySwiftStruct.swift

@@ -14,10 +14,12 @@
 
 public struct MySwiftStruct {
 
-  public var number: Int
+  private var cap: Int
+  private var len: Int
 
-  public init(number: Int) {
-    self.number = number
+  public init(cap: Int, len: Int) {
+    self.cap = cap
+    self.len = len
   }
 
   public func voidMethod() {
@@ -38,6 +40,20 @@ public struct MySwiftStruct {
     return 12
   }
 
+  public func getCapacity() -> Int {
+    self.cap
+  }
+
+  public func getLength() -> Int {
+    self.len
+  }
+
+  public mutating func increaseCap(by value: Int) -> Int {
+    precondition(value > 0)
+     self.cap += value
+    return self.cap
+  }
+
   public func makeRandomIntMethod() -> Int {
     return Int.random(in: 1..<256)
   }

Samples/SwiftKitSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java

@@ -24,15 +24,13 @@
 import org.swift.swiftkit.SwiftKit;
 import org.swift.swiftkit.SwiftValueWitnessTable;
 
-import java.util.Arrays;
-
 public class HelloJava2Swift {
 
     public static void main(String[] args) {
         boolean traceDowncalls = Boolean.getBoolean("jextract.trace.downcalls");
         System.out.println("Property: jextract.trace.downcalls = " + traceDowncalls);
 
-        System.out.print("Property: java.library.path = " +SwiftKit.getJavaLibraryPath());
+        System.out.print("Property: java.library.path = " + SwiftKit.getJavaLibraryPath());
 
         examples();
     }
@@ -44,23 +42,23 @@ static void examples() {
 
         // Example of using an arena; MyClass.deinit is run at end of scope
         try (var arena = SwiftArena.ofConfined()) {
-            MySwiftClass obj = new MySwiftClass(arena, 2222, 7777);
-
-            // just checking retains/releases work
-            SwiftKit.retain(obj.$memorySegment());
-            SwiftKit.release(obj.$memorySegment());
+             MySwiftClass obj = new MySwiftClass(arena, 2222, 7777);
 
-            obj.voidMethod();
-            obj.takeIntMethod(42);
+             // just checking retains/releases work
+             SwiftKit.retain(obj.$memorySegment());
+             SwiftKit.release(obj.$memorySegment());
 
-            MySwiftStruct swiftValue = new MySwiftStruct(12);
+             obj.voidMethod();
+             obj.takeIntMethod(42);
 
+            MySwiftStruct swiftValue = new MySwiftStruct(arena, 2222, 1111);
         }
 
         System.out.println("DONE.");
     }
 
     public static native long jniWriteString(String str);
+
     public static native long jniGetInt();
 
 }

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

@@ -28,7 +28,6 @@ public class MySwiftClassTest {
     void checkPaths(Throwable throwable) {
         var paths = SwiftKit.getJavaLibraryPath().split(":");
         for (var path : paths) {
-            System.out.println("CHECKING PATH: " + path);
             Stream.of(new File(path).listFiles())
                     .filter(file -> !file.isDirectory())
                     .forEach((file) -> {

Samples/SwiftKitSampleApp/src/test/java/com/example/swift/MySwiftStructTest.java renamed to Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/MySwiftStructTest.java

@@ -12,26 +12,24 @@
 //
 //===----------------------------------------------------------------------===//
 
-package com.example.swift;
+package org.swift.swiftkit;
 
-import org.junit.jupiter.api.Disabled;
+import com.example.swift.MySwiftStruct;
 import org.junit.jupiter.api.Test;
-import org.swift.swiftkit.SwiftArena;
-import org.swift.swiftkit.SwiftKit;
-
-import java.io.File;
-import java.util.stream.Stream;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class MySwiftStructTest {
 
     @Test
-    void test_MySwiftClass_voidMethod() {
+    void create_struct() {
         try (var arena = SwiftArena.ofConfined()) {
-            MySwiftStruct o = new MySwiftStruct(12);
-//        o.voidMethod();
+            long cap = 12;
+            long len = 34;
+            var struct = new MySwiftStruct(arena, cap, len);
+
+            assertEquals(cap, struct.getCapacity());
+            assertEquals(len, struct.getLength());
         }
     }
-
 }

Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/SwiftArenaTest.java

@@ -15,6 +15,7 @@
 package org.swift.swiftkit;
 
 import com.example.swift.MySwiftClass;
+import com.example.swift.MySwiftStruct;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.DisabledIf;
@@ -47,8 +48,44 @@ public void arena_releaseClassOnClose_class_ok() {
             release(obj.$memorySegment());
             assertEquals(1, retainCount(obj.$memorySegment()));
         }
+    }
+
+    // FIXME: The destroy witness table call hangs on x86_64 platforms during the destroy witness table call
+    //        See: https://github.com/swiftlang/swift-java/issues/97
+    @Test
+    public void arena_markAsDestroyed_preventUseAfterFree_class() {
+        MySwiftClass unsafelyEscapedOutsideArenaScope = null;
+
+        try (var arena = SwiftArena.ofConfined()) {
+            var obj = new MySwiftClass(arena,1, 2);
+            unsafelyEscapedOutsideArenaScope = obj;
+        }
+
+        try {
+            unsafelyEscapedOutsideArenaScope.echoIntMethod(1);
+            fail("Expected exception to be thrown! Object was suposed to be dead.");
+        } catch (IllegalStateException ex) {
+            return;
+        }
+    }
+
+    // FIXME: The destroy witness table call hangs on x86_64 platforms during the destroy witness table call
+    //        See: https://github.com/swiftlang/swift-java/issues/97
+    @Test
+    public void arena_markAsDestroyed_preventUseAfterFree_struct() {
+        MySwiftStruct unsafelyEscapedOutsideArenaScope = null;
 
-        // TODO: should we zero out the $memorySegment perhaps?
+        try (var arena = SwiftArena.ofConfined()) {
+            var s = new MySwiftStruct(arena,1, 2);
+            unsafelyEscapedOutsideArenaScope = s;
+        }
+
+        try {
+            unsafelyEscapedOutsideArenaScope.echoIntMethod(1);
+            fail("Expected exception to be thrown! Object was suposed to be dead.");
+        } catch (IllegalStateException ex) {
+            return;
+        }
     }
 
     @Test

Sources/JExtractSwift/Convenience/SwiftSyntax+Extensions.swift

@@ -52,13 +52,22 @@ extension ImplicitlyUnwrappedOptionalTypeSyntax {
   }
 }
 
-extension TypeSyntax {
-  fileprivate var isActorSystem: Bool {
-    self.trimmedDescription == "ActorSystem"
+extension SyntaxProtocol {
+
+  var asNominalTypeKind: NominalTypeKind {
+    if isClass {
+      .class
+    } else if isActor {
+      .actor
+    } else if isStruct {
+      .struct
+    } else if isEnum {
+      .enum
+    } else {
+      fatalError("Unknown nominal kind: \(self)")
+    }
   }
-}
 
-extension DeclSyntaxProtocol {
   var isClass: Bool {
     return self.is(ClassDeclSyntax.self)
   }
@@ -79,11 +88,8 @@ extension DeclSyntaxProtocol {
 extension DeclModifierSyntax {
   var isAccessControl: Bool {
     switch self.name.tokenKind {
-    case .keyword(.private): fallthrough
-    case .keyword(.fileprivate): fallthrough
-    case .keyword(.internal): fallthrough
-    case .keyword(.package): fallthrough
-    case .keyword(.public):
+    case .keyword(.private), .keyword(.fileprivate), .keyword(.internal), .keyword(.package),
+      .keyword(.public):
       return true
     default:
       return false

Sources/JExtractSwift/ImportedDecls.swift

@@ -44,18 +44,19 @@ public struct ImportedNominalType: ImportedDecl {
     TranslatedType(
       cCompatibleConvention: .direct,
       originalSwiftType: "\(raw: swiftTypeName)",
+      originalSwiftTypeKind: self.kind,
       cCompatibleSwiftType: "UnsafeRawPointer",
       cCompatibleJavaMemoryLayout: .heapObject,
       javaType: javaType
     )
   }
-  
+
   public var isReferenceType: Bool {
     switch self.kind {
     case .class, .actor:
-      return true
-    case .enum, .struct:
-      return false
+      true
+    default:
+      false
     }
   }
 
@@ -68,11 +69,40 @@ public struct ImportedNominalType: ImportedDecl {
   }
 }
 
+// TODO: replace this with `SwiftNominalTypeDeclaration.Kind`
 public enum NominalTypeKind {
   case `actor`
   case `class`
   case `enum`
   case `struct`
+  case `void`  // TODO: NOT NOMINAL, BUT...
+  case function  // TODO: NOT NOMINAL, BUT...
+  case primitive  // TODO: NOT NOMINAL, BUT...
+
+  var isReferenceType: Bool {
+    switch self {
+    case .actor, .class: true
+    case .enum, .struct: false
+    case .void, .function, .primitive: false
+    }
+  }
+
+  var isValueType: Bool {
+    switch self {
+    case .actor, .class: false
+    case .enum, .struct: true
+    case .void, .function, .primitive: false
+    }
+  }
+
+  var isVoid: Bool {
+    switch self {
+    case .actor, .class: false
+    case .enum, .struct: false
+    case .void: true
+    case .function, .primitive: false
+    }
+  }
 }
 
 public struct ImportedParam {
@@ -99,7 +129,7 @@ public struct ImportedParam {
   var effectiveName: String? {
     firstName ?? secondName
   }
-  
+
   var effectiveValueName: String {
     secondName ?? firstName ?? "_"
   }
@@ -199,13 +229,13 @@ public struct ImportedFunc: ImportedDecl, CustomStringConvertible {
       case nil, .wrapper:
         break
 
-      case .pointer:
+      case .pointer where !isInit:
         let selfParam: FunctionParameterSyntax = "self$: $swift_pointer"
         params.append(
           ImportedParam(syntax: selfParam, type: parent)
         )
 
-      case .memorySegment:
+      case .memorySegment where !isInit:
         let selfParam: FunctionParameterSyntax = "self$: $java_lang_foreign_MemorySegment"
         var parentForSelf = parent
         parentForSelf.javaType = .javaForeignMemorySegment
@@ -215,6 +245,9 @@ public struct ImportedFunc: ImportedDecl, CustomStringConvertible {
 
       case .swiftThunkSelf:
         break
+
+      default:
+        break
       }
 
       // TODO: add any metadata for generics and other things we may need to add here
@@ -233,6 +266,11 @@ public struct ImportedFunc: ImportedDecl, CustomStringConvertible {
 
   public var isInit: Bool = false
 
+  public var isIndirectReturn: Bool {
+    returnType.isValueType ||
+      (isInit && (parent?.isValueType ?? false))
+  }
+
   public init(
     module: String,
     decl: any DeclSyntaxProtocol,
@@ -269,9 +307,9 @@ extension ImportedFunc: Hashable {
     self.swiftDecl.id.hash(into: &hasher)
   }
 
-  public static func ==(lhs: ImportedFunc, rhs: ImportedFunc) -> Swift.Bool {
-    lhs.parent?.originalSwiftType.id == rhs.parent?.originalSwiftType.id &&
-    lhs.swiftDecl.id == rhs.swiftDecl.id
+  public static func == (lhs: ImportedFunc, rhs: ImportedFunc) -> Swift.Bool {
+    lhs.parent?.originalSwiftType.id == rhs.parent?.originalSwiftType.id
+      && lhs.swiftDecl.id == rhs.swiftDecl.id
   }
 }
 
@@ -394,8 +432,8 @@ public struct ImportedVariable: ImportedDecl, CustomStringConvertible {
         )
 
       case nil,
-           .wrapper,
-           .swiftThunkSelf:
+        .wrapper,
+        .swiftThunkSelf:
         break
       }
     }