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Merged
tsapeta merged 2 commits into from
Jun 17, 2026
Merged

Emit unowned-this closures for synchronous @JS bindings #20

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c403548
[macros] Emit unowned-`this` closures for synchronous `@JS` bindings
tsapeta Jun 16, 2026
0edc92a
[tests] Update sync binding fixtures to typed closure params
tsapeta Jun 16, 2026
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28 changes: 24 additions & 4 deletions apple/Sources/ExpoModulesMacros/DecorateModuleBuilder.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -201,9 +201,24 @@ internal struct JSFunction {
/// body never references `appContext`, so the capture and guard are omitted to avoid the
/// unused-capture warning.
var decorateStatements: String {
// Synchronous `@JS` functions never decode `this` (the receiver is the module's real `self`), so
// they bind through the unowned-`this` `setProperty` overload, which hands `this` in as a borrowed
// `JavaScriptUnownedValue` instead of allocating an owning `JavaScriptValue` and forming its
// `weak`-runtime reference on every call. The first parameter is typed `borrowing
// JavaScriptUnownedValue` to select that (otherwise `@_disfavoredOverload`) overload — which
// requires the *parenthesized, fully typed* parameter list, since Swift rejects a type annotation
// on a shorthand `{ [capture] name, name in }` parameter. Async functions keep the untyped
// shorthand and the owning-`this` overload: there is no unowned-`this` async variant and the buffer
// escapes into the task anyway.
let captures = usesAppContext ? "[weak appContext, self]" : "[self]"
let parameters =
isAsync
? "this, arguments"
: "(this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer)"

if usesAppContext {
return """
object.setProperty("\(jsName)") { [weak appContext, self] this, arguments in
object.setProperty("\(jsName)") { \(captures) \(parameters) in
guard let appContext else {
throw Exceptions.AppContextLost()
}
Expand All @@ -212,7 +227,7 @@ internal struct JSFunction {
"""
}
return """
object.setProperty("\(jsName)") { [self] this, arguments in
object.setProperty("\(jsName)") { \(captures) \(parameters) in
\(bodyStatements(indent: " "))
}
"""
Expand Down Expand Up @@ -323,9 +338,14 @@ internal struct JSProperty {
.split(separator: "\n", omittingEmptySubsequences: false)
.map { " \($0)" }
.joined(separator: "\n")
// Property `get`/`set` accessors are always synchronous and never decode `this`, so they bind
// through the unowned-`this` `setProperty` overload like sync functions. The parameter list is
// parenthesized and fully typed because Swift rejects a type annotation on a shorthand closure
// parameter; the explicit `borrowing JavaScriptUnownedValue` selects the unowned-`this` overload.
let parameters = "(this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer)"
if usesAppContext {
return """
\(descriptorName).setProperty("\(key)") { [weak appContext, self] this, arguments in
\(descriptorName).setProperty("\(key)") { [weak appContext, self] \(parameters) in
guard let appContext else {
throw Exceptions.AppContextLost()
}
Expand All @@ -334,7 +354,7 @@ internal struct JSProperty {
"""
}
return """
\(descriptorName).setProperty("\(key)") { [self] this, arguments in
\(descriptorName).setProperty("\(key)") { [self] \(parameters) in
\(indentedBody)
}
"""
Expand Down
32 changes: 16 additions & 16 deletions apple/Tests/ExpoModulesMacrosTests/ExpoModuleMacroTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("greet") { [self] this, arguments in
object.setProperty("greet") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count == 1 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "greet", received: arguments.count, required: 1, maximum: 1))
}
Expand Down Expand Up @@ -141,7 +141,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("add") { [self] this, arguments in
object.setProperty("add") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count == 2 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "add", received: arguments.count, required: 2, maximum: 2))
}
Expand Down Expand Up @@ -179,7 +179,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("resize") { [self] this, arguments in
object.setProperty("resize") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count >= 1 && arguments.count <= 2 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "resize", received: arguments.count, required: 1, maximum: 2))
}
Expand Down Expand Up @@ -222,7 +222,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("tag") { [weak appContext, self] this, arguments in
object.setProperty("tag") { [weak appContext, self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard let appContext else {
throw Exceptions.AppContextLost()
}
Expand Down Expand Up @@ -268,7 +268,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("ping") { [self] this, arguments in
object.setProperty("ping") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count >= 0 && arguments.count <= 1 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "ping", received: arguments.count, required: 0, maximum: 1))
}
Expand Down Expand Up @@ -317,7 +317,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("transform") { [weak appContext, self] this, arguments in
object.setProperty("transform") { [weak appContext, self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard let appContext else {
throw Exceptions.AppContextLost()
}
Expand Down Expand Up @@ -364,7 +364,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("describe") { [weak appContext, self] this, arguments in
object.setProperty("describe") { [weak appContext, self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard let appContext else {
throw Exceptions.AppContextLost()
}
Expand Down Expand Up @@ -404,7 +404,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("doReset") { [self] this, arguments in
object.setProperty("doReset") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count == 0 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "doReset", received: arguments.count, required: 0, maximum: 0))
}
Expand Down Expand Up @@ -513,7 +513,7 @@ struct ExpoModuleMacroTests {
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
let statusDescriptor = runtime.createObject()
statusDescriptor.setProperty("enumerable", value: true)
statusDescriptor.setProperty("get") { [self] this, arguments in
statusDescriptor.setProperty("get") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
return self.status.toJavaScriptValue(in: runtime)
}
object.defineProperty("status", descriptor: statusDescriptor)
Expand Down Expand Up @@ -548,10 +548,10 @@ struct ExpoModuleMacroTests {
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
let readyDescriptor = runtime.createObject()
readyDescriptor.setProperty("enumerable", value: true)
readyDescriptor.setProperty("get") { [self] this, arguments in
readyDescriptor.setProperty("get") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
return self.ready.toJavaScriptValue(in: runtime)
}
readyDescriptor.setProperty("set") { [self] this, arguments in
readyDescriptor.setProperty("set") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
self.ready = try arguments.unownedValue(at: 0).asBool()
return .undefined
}
Expand Down Expand Up @@ -593,13 +593,13 @@ struct ExpoModuleMacroTests {
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
let configDescriptor = runtime.createObject()
configDescriptor.setProperty("enumerable", value: true)
configDescriptor.setProperty("get") { [weak appContext, self] this, arguments in
configDescriptor.setProperty("get") { [weak appContext, self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard let appContext else {
throw Exceptions.AppContextLost()
}
return try MyRecord.getDynamicType().castToJS(self.config, appContext: appContext, in: runtime)
}
configDescriptor.setProperty("set") { [weak appContext, self] this, arguments in
configDescriptor.setProperty("set") { [weak appContext, self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard let appContext else {
throw Exceptions.AppContextLost()
}
Expand Down Expand Up @@ -645,7 +645,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("greet") { [self] this, arguments in
object.setProperty("greet") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count == 1 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "greet", received: arguments.count, required: 1, maximum: 1))
}
Expand All @@ -655,7 +655,7 @@ struct ExpoModuleMacroTests {
}
let statusDescriptor = runtime.createObject()
statusDescriptor.setProperty("enumerable", value: true)
statusDescriptor.setProperty("get") { [self] this, arguments in
statusDescriptor.setProperty("get") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
return self.status.toJavaScriptValue(in: runtime)
}
object.defineProperty("status", descriptor: statusDescriptor)
Expand Down Expand Up @@ -687,7 +687,7 @@ struct ExpoModuleMacroTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("compute") { [self] this, arguments in
object.setProperty("compute") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count == 0 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "compute", received: arguments.count, required: 0, maximum: 0))
}
Expand Down
2 changes: 1 addition & 1 deletion apple/Tests/ExpoModulesMacrosTests/SharedObjectMacroTests.swift
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Expand Up @@ -336,7 +336,7 @@ struct ExpoModuleClassesTests {

@JavaScriptActor
public func _decorateModule(object: borrowing JavaScriptObject, in runtime: JavaScriptRuntime, appContext: AppContext) throws {
object.setProperty("ping") { [self] this, arguments in
object.setProperty("ping") { [self] (this: borrowing JavaScriptUnownedValue, arguments: consuming JavaScriptValuesBuffer) in
guard arguments.count == 0 else {
throw Exceptions.ArgumentsRangeMismatch((functionName: "ping", received: arguments.count, required: 0, maximum: 0))
}
Expand Down
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