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Fix JNI generation for sending closures #700

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Merged
ktoso merged 2 commits into from
Apr 14, 2026
Merged

Fix JNI generation for sending closures #700

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ff986a1
Fix JNI generation for Swift 6.2 sending closures
iDevid Apr 13, 2026
810ef95
Fix Swift 6.2 sending closure errors in generated JNI async thunks
iDevid Apr 14, 2026
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31 changes: 26 additions & 5 deletions Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+NativeTranslation.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1633,23 +1633,34 @@ extension JNISwift2JavaGenerator {
// Global ref all indirect returns
for outParameter in nativeFunctionSignature.result.outParameters {
printer.print(
"let \(outParameter.name) = environment.interface.NewGlobalRef(environment, \(outParameter.name))"
"nonisolated(unsafe) let \(outParameter.name) = environment.interface.NewGlobalRef(environment, \(outParameter.name))"
)
globalRefs.append(outParameter.name)
}

// We also need to global ref any objects passed in
for parameter in nativeFunctionSignature.parameters.flatMap(\.parameters) where !parameter.type.isPrimitive {
printer.print("let \(parameter.name) = environment.interface.NewGlobalRef(environment, \(parameter.name))")
printer.print("nonisolated(unsafe) let \(parameter.name) = environment.interface.NewGlobalRef(environment, \(parameter.name))")
globalRefs.append(parameter.name)
}

printer.print(
"""
let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
nonisolated(unsafe) let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
"""
)

if let selfParameter = nativeFunctionSignature.selfParameter {
for parameter in selfParameter.parameters {
printer.print("nonisolated(unsafe) let \(parameter.name)Sendable$ = \(parameter.name)$")
}
}
if let selfTypeParameter = nativeFunctionSignature.selfTypeParameter {
for parameter in selfTypeParameter.parameters {
printer.print("nonisolated(unsafe) let \(parameter.name)Sendable$ = \(parameter.name)$")
}
}

func printDo(printer: inout CodePrinter) {
// Make sure try/await are printed when necessary and avoid duplicate, or wrong-order, keywords (which would cause warnings)
let placeholderWithoutTry =
Expand Down Expand Up @@ -1692,6 +1703,16 @@ extension JNISwift2JavaGenerator {
}

func printTaskBody(printer: inout CodePrinter) {
if let selfParameter = nativeFunctionSignature.selfParameter {
for parameter in selfParameter.parameters {
printer.print("let \(parameter.name)$ = \(parameter.name)Sendable$")
}
}
if let selfTypeParameter = nativeFunctionSignature.selfTypeParameter {
for parameter in selfTypeParameter.parameters {
printer.print("let \(parameter.name)$ = \(parameter.name)Sendable$")
}
}
printer.printBraceBlock("defer") { printer in
// Defer might on any thread, so we need to attach environment.
printer.print("let deferEnvironment = try! JavaVirtualMachine.shared().environment()")
Expand Down Expand Up @@ -1722,8 +1743,8 @@ extension JNISwift2JavaGenerator {
printer.printHashIfBlock("swift(>=6.2)") { printer in
printer.printBraceBlock("if #available(macOS 26.0, iOS 26.0, watchOS 26.0, tvOS 26.0, *)") { printer in
printer.printBraceBlock("task = Task.immediate") { printer in
// Immediate runs on the caller thread, so we don't need to attach the environment again.
printer.print("var environment = environment!") // this is to ensure we always use the same environment name, even though we are rebinding it.
// Even immediate tasks are a sending closure in Swift 6.2+, so reattach instead of capturing the caller's environment directly.
printer.print("var environment = try! JavaVirtualMachine.shared().environment()")
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printTaskBody(printer: &printer)
}
}
Expand Down
20 changes: 10 additions & 10 deletions Tests/JExtractSwiftTests/JNI/JNIAsyncTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -61,12 +61,12 @@ struct JNIAsyncTests {
"""
@_cdecl("Java_com_example_swift_SwiftModule__00024asyncVoid__Ljava_util_concurrent_CompletableFuture_2")
public func Java_com_example_swift_SwiftModule__00024asyncVoid__Ljava_util_concurrent_CompletableFuture_2(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, result_future: jobject?) {
let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
nonisolated(unsafe) let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
var task: Task<Void, Never>? = nil
#if swift(>=6.2)
if #available(macOS 26.0, iOS 26.0, watchOS 26.0, tvOS 26.0, *) {
task = Task.immediate {
var environment = environment!
var environment = try! JavaVirtualMachine.shared().environment()
defer {
let deferEnvironment = try! JavaVirtualMachine.shared().environment()
deferEnvironment.interface.DeleteGlobalRef(deferEnvironment, globalFuture)
Expand Down Expand Up @@ -137,12 +137,12 @@ struct JNIAsyncTests {
"""
@_cdecl("Java_com_example_swift_SwiftModule__00024async__Ljava_util_concurrent_CompletableFuture_2")
public func Java_com_example_swift_SwiftModule__00024async__Ljava_util_concurrent_CompletableFuture_2(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, result_future: jobject?) {
let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
nonisolated(unsafe) let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
var task: Task<Void, Never>? = nil
#if swift(>=6.2)
if #available(macOS 26.0, iOS 26.0, watchOS 26.0, tvOS 26.0, *) {
task = Task.immediate {
var environment = environment!
var environment = try! JavaVirtualMachine.shared().environment()
defer {
let deferEnvironment = try! JavaVirtualMachine.shared().environment()
deferEnvironment.interface.DeleteGlobalRef(deferEnvironment, globalFuture)
Expand Down Expand Up @@ -227,12 +227,12 @@ struct JNIAsyncTests {
"""
@_cdecl("Java_com_example_swift_SwiftModule__00024async__JLjava_util_concurrent_CompletableFuture_2")
public func Java_com_example_swift_SwiftModule__00024async__JLjava_util_concurrent_CompletableFuture_2(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, i: jlong, result_future: jobject?) {
let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
nonisolated(unsafe) let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
var task: Task<Void, Never>? = nil
#if swift(>=6.2)
if #available(macOS 26.0, iOS 26.0, watchOS 26.0, tvOS 26.0, *) {
task = Task.immediate {
var environment = environment!
var environment = try! JavaVirtualMachine.shared().environment()
defer {
let deferEnvironment = try! JavaVirtualMachine.shared().environment()
deferEnvironment.interface.DeleteGlobalRef(deferEnvironment, globalFuture)
Expand Down Expand Up @@ -320,12 +320,12 @@ struct JNIAsyncTests {
guard let c$ else {
fatalError("c memory address was null in call to \\(#function)!")
}
let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
nonisolated(unsafe) let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
var task: Task<Void, Never>? = nil
#if swift(>=6.2)
if #available(macOS 26.0, iOS 26.0, watchOS 26.0, tvOS 26.0, *) {
task = Task.immediate {
var environment = environment!
var environment = try! JavaVirtualMachine.shared().environment()
defer {
let deferEnvironment = try! JavaVirtualMachine.shared().environment()
deferEnvironment.interface.DeleteGlobalRef(deferEnvironment, globalFuture)
Expand Down Expand Up @@ -403,8 +403,8 @@ struct JNIAsyncTests {
"""
@_cdecl("Java_com_example_swift_SwiftModule__00024async__Ljava_lang_String_2Ljava_util_concurrent_CompletableFuture_2")
public func Java_com_example_swift_SwiftModule__00024async__Ljava_lang_String_2Ljava_util_concurrent_CompletableFuture_2(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, s: jstring?, result_future: jobject?) {
let s = environment.interface.NewGlobalRef(environment, s)
let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
nonisolated(unsafe) let s = environment.interface.NewGlobalRef(environment, s)
nonisolated(unsafe) let globalFuture = environment.interface.NewGlobalRef(environment, result_future)
...
defer {
let deferEnvironment = try! JavaVirtualMachine.shared().environment()
Expand Down
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