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jextract/jni: Add nativeJavaType to TranslatedResult for explicit type handling #722

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Merged
ktoso merged 4 commits into from
Apr 24, 2026
Merged

jextract/jni: Add nativeJavaType to TranslatedResult for explicit type handling #722

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dd7c606
Add nativeJavaType to TranslatedResult
sidepelican Apr 24, 2026
99a9626
Rename and unuse SwiftResult
sidepelican Apr 24, 2026
3a8c237
Remove unused conversion
sidepelican Apr 24, 2026
17b9830
More accurate direct result comversion
sidepelican Apr 24, 2026
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12 changes: 6 additions & 6 deletions Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -660,7 +660,7 @@ extension JNISwift2JavaGenerator {
}

let translatedSignature = translatedDecl.translatedFunctionSignature
let resultType = translatedSignature.resultType.javaType
let resultType = translatedSignature.result.javaType
var parameters = translatedDecl.translatedFunctionSignature.parameters.map { $0.parameter.renderParameter() }
let throwsClause = translatedDecl.throwsClause()

Expand Down Expand Up @@ -714,7 +714,7 @@ extension JNISwift2JavaGenerator {
let globalArenaName = "SwiftMemoryManagement.DEFAULT_SWIFT_JAVA_AUTO_ARENA"
let arguments = translatedDecl.translatedFunctionSignature.parameters.map(\.parameter.name) + [globalArenaName]
let call = "\(translatedDecl.name)(\(arguments.joined(separator: ", ")))"
if translatedDecl.translatedFunctionSignature.resultType.javaType.isVoid {
if translatedDecl.translatedFunctionSignature.result.javaType.isVoid {
printer.print("\(call);")
} else {
printer.print("return \(call);")
Expand Down Expand Up @@ -792,7 +792,7 @@ extension JNISwift2JavaGenerator {
}

// Indirect return receivers
for outParameter in translatedFunctionSignature.resultType.outParameters {
for outParameter in translatedFunctionSignature.result.outParameters {
printer.print(
"\(outParameter.type) \(outParameter.name) = \(outParameter.allocation.render(type: outParameter.type));"
)
Expand All @@ -807,15 +807,15 @@ extension JNISwift2JavaGenerator {
"\(effectiveParentName.fullName).\(translatedDecl.nativeFunctionName)(\(arguments.joined(separator: ", ")))"

//=== Part 4: Convert the return value.
if translatedFunctionSignature.resultType.javaType.isVoid {
if translatedFunctionSignature.result.javaType.isVoid {
printer.print("\(downcall);")
} else {
let result: String
if translatedDecl.nativeFunctionSignature.result.javaType.isVoid {
printer.print("\(downcall);")
result = translatedFunctionSignature.resultType.conversion.render(&printer, "")
result = translatedFunctionSignature.result.conversion.render(&printer, "")
} else {
result = translatedFunctionSignature.resultType.conversion.render(&printer, downcall)
result = translatedFunctionSignature.result.conversion.render(&printer, downcall)
}
printer.print("return \(result);")
}
Expand Down
94 changes: 52 additions & 42 deletions Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaTranslation.swift
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -117,13 +117,20 @@ extension JNISwift2JavaGenerator {

let conversions = try enumCase.parameters.enumerated().map { idx, parameter in
let resultName = parameter.name ?? "arg\(idx)"
let result = SwiftResult(convention: .direct, type: parameter.type)
var translatedResult = try self.translate(swiftResult: result, methodName: methodName, resultName: resultName)
var translatedResult = try self.translateResult(
swiftType: parameter.type,
methodName: methodName,
resultName: resultName
)
translatedResult.conversion = .replacingPlaceholder(
translatedResult.conversion,
placeholder: "$nativeParameters.\(resultName)",
)
let nativeResult = try nativeTranslation.translate(swiftResult: result, methodName: methodName, resultName: resultName)
let nativeResult = try nativeTranslation.translateResult(
swiftType: parameter.type,
methodName: methodName,
resultName: resultName
)
return (translated: translatedResult, native: nativeResult)
}

Expand Down Expand Up @@ -179,8 +186,9 @@ extension JNISwift2JavaGenerator {
conversion: .typeMetadataAddress(.placeholder),
),
parameters: [],
resultType: TranslatedResult(
result: TranslatedResult(
javaType: .optional(caseType),
nativeJavaType: nativeParametersType,
outParameters: conversions.flatMap(\.translated.outParameters),
conversion: enumCase.parameters.isEmpty
? constructRecordConversion
Expand Down Expand Up @@ -323,7 +331,7 @@ extension JNISwift2JavaGenerator {
)
}

let translatedResult = try translate(swiftResult: SwiftResult(convention: .direct, type: swiftType.resultType), methodName: name)
let translatedResult = try translateResult(swiftType: swiftType.resultType, methodName: name)
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@ktoso ktoso Apr 24, 2026

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Ok change thx


return TranslatedFunctionType(
name: name,
Expand Down Expand Up @@ -369,8 +377,8 @@ extension JNISwift2JavaGenerator {
exceptions.append(.integerOverflow)
}

let resultType = try translate(
swiftResult: functionSignature.result,
let resultType = try translateResult(
swiftType: functionSignature.result.type,
methodName: methodName,
genericParameters: functionSignature.genericParameters,
genericRequirements: functionSignature.genericRequirements,
Expand All @@ -380,7 +388,7 @@ extension JNISwift2JavaGenerator {
selfParameter: selfParameter,
selfTypeParameter: selfTypeParameter,
parameters: parameters,
resultType: resultType,
result: resultType,
exceptions: exceptions,
)
}
Expand Down Expand Up @@ -699,13 +707,13 @@ extension JNISwift2JavaGenerator {
switch mode {
case .completableFuture:
nativeFutureType = .completableFuture(nativeFunctionSignature.result.javaType)
translatedFutureType = .completableFuture(translatedFunctionSignature.resultType.javaType)
translatedFutureType = .completableFuture(translatedFunctionSignature.result.javaType)
completeMethodID = "_JNIMethodIDCache.CompletableFuture.complete"
completeExceptionallyMethodID = "_JNIMethodIDCache.CompletableFuture.completeExceptionally"

case .legacyFuture:
nativeFutureType = .simpleCompletableFuture(nativeFunctionSignature.result.javaType)
translatedFutureType = .future(translatedFunctionSignature.resultType.javaType)
translatedFutureType = .future(translatedFunctionSignature.result.javaType)
completeMethodID = "_JNIMethodIDCache.SimpleCompletableFuture.complete"
completeExceptionallyMethodID = "_JNIMethodIDCache.SimpleCompletableFuture.completeExceptionally"
}
Expand All @@ -716,9 +724,10 @@ extension JNISwift2JavaGenerator {
allocation: .new,
)

let result = translatedFunctionSignature.resultType
translatedFunctionSignature.resultType = TranslatedResult(
let result = translatedFunctionSignature.result
translatedFunctionSignature.result = TranslatedResult(
javaType: translatedFutureType,
nativeJavaType: .void,
annotations: result.annotations,
outParameters: result.outParameters + [futureOutParameter],
conversion: .method(
Expand Down Expand Up @@ -890,15 +899,13 @@ extension JNISwift2JavaGenerator {
}
}

func translate(
swiftResult: SwiftResult,
func translateResult(
swiftType: SwiftType,
methodName: String,
resultName: String = "result",
genericParameters: [SwiftGenericParameterDeclaration] = [],
genericRequirements: [SwiftGenericRequirement] = [],
) throws -> TranslatedResult {
let swiftType = swiftResult.type

// If the result type should cause any annotations on the method, include them here.
let resultAnnotations: [JavaAnnotation] = getJavaTypeAnnotations(swiftType: swiftType, config: config)

Expand Down Expand Up @@ -948,6 +955,7 @@ extension JNISwift2JavaGenerator {
case .foundationUUID, .essentialsUUID:
return TranslatedResult(
javaType: .javaUtilUUID,
nativeJavaType: .javaLangString,
outParameters: [],
conversion: .method(
.constant("java.util.UUID"),
Expand All @@ -963,6 +971,7 @@ extension JNISwift2JavaGenerator {

return TranslatedResult(
javaType: javaType,
nativeJavaType: javaType,
annotations: resultAnnotations,
outParameters: [],
conversion: .placeholder,
Expand Down Expand Up @@ -990,6 +999,7 @@ extension JNISwift2JavaGenerator {
if nominalType.nominalTypeDecl.isGeneric {
return TranslatedResult(
javaType: javaType,
nativeJavaType: .void,
annotations: resultAnnotations,
outParameters: [.init(name: resultName, type: ._OutSwiftGenericInstance, allocation: .new)],
conversion: .wrapMemoryAddressUnsafe(
Expand All @@ -1003,14 +1013,15 @@ extension JNISwift2JavaGenerator {
} else {
return TranslatedResult(
javaType: javaType,
nativeJavaType: .long,
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@sidepelican sidepelican Apr 24, 2026

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This isn't a new concern; it just makes an existing assumption explicit.
For example, using .wrapMemoryAddressUnsafe already implies we know the native return type is long.

annotations: resultAnnotations,
outParameters: [],
conversion: .wrapMemoryAddressUnsafe(.placeholder, javaType),
)
}

case .tuple([]):
return TranslatedResult(javaType: .void, outParameters: [], conversion: .placeholder)
return TranslatedResult(javaType: .void, nativeJavaType: .void, outParameters: [], conversion: .placeholder)

case .tuple(let elements) where !elements.isEmpty:
return try translateTupleResult(
Expand Down Expand Up @@ -1152,8 +1163,8 @@ extension JNISwift2JavaGenerator {
let outParamName = "\(resultName)_\(idx)$"

// Determine the Java type for this element
let elementResult = try translate(
swiftResult: .init(convention: .indirect, type: element.type),
let elementResult = try translateResult(
swiftType: element.type,
methodName: methodName,
resultName: outParamName,
genericParameters: genericParameters,
Expand All @@ -1162,9 +1173,9 @@ extension JNISwift2JavaGenerator {

// out names are always ...$N, no need to use real named tuple names here, this is just for the thunk
elementOutParamNames.append(outParamName)
outParameters.append(contentsOf: elementResult.outParameters)

// FIXME: More accurate determination of whether the result is direct or indirect
if elementResult.outParameters.isEmpty {
if !elementResult.nativeJavaType.isVoid {
// Convert direct result to indirect result.
// For most class types (Swift wrapper classes), the JNI native representation
// is 'long' (a memory address). However, String is a native JNI reference
Expand All @@ -1184,7 +1195,6 @@ extension JNISwift2JavaGenerator {
)
elementConversions.append(elementResult.conversion)
} else {
outParameters.append(contentsOf: elementResult.outParameters)
elementConversions.append(.placeToVar(elementResult.conversion, name: "\(resultName)_\(idx)"))
}
elementJavaTypes.append(elementResult.javaType)
Expand Down Expand Up @@ -1228,6 +1238,7 @@ extension JNISwift2JavaGenerator {

return TranslatedResult(
javaType: javaResultType,
nativeJavaType: .void,
annotations: tupleAnnotations,
outParameters: outParameters,
conversion: javaNativeConversionStep
Expand Down Expand Up @@ -1271,6 +1282,7 @@ extension JNISwift2JavaGenerator {
if let nextIntergralTypeWithSpaceForByte = javaType.nextIntergralTypeWithSpaceForByte {
return TranslatedResult(
javaType: .class(package: nil, name: returnType),
nativeJavaType: nextIntergralTypeWithSpaceForByte.javaType,
annotations: parameterAnnotations,
outParameters: [],
conversion: .combinedValueToOptional(
Expand All @@ -1287,6 +1299,7 @@ extension JNISwift2JavaGenerator {
// use an indirect return for the discriminator.
return TranslatedResult(
javaType: .class(package: nil, name: returnType),
nativeJavaType: javaType,
annotations: parameterAnnotations,
outParameters: [
OutParameter(name: discriminatorName, type: .array(.byte), allocation: .newArray(.byte, size: 1))
Expand Down Expand Up @@ -1314,33 +1327,26 @@ extension JNISwift2JavaGenerator {
genericRequirements: genericRequirements,
)

let wrappedValueResult = try translate(
swiftResult: SwiftResult(convention: .direct, type: swiftType),
let wrappedValueResult = try translateResult(
swiftType: swiftType,
methodName: methodName,
resultName: resultName + "Wrapped$",
genericParameters: genericParameters,
genericRequirements: genericRequirements,
)

// FIXME: More accurate JavaType using NativeJavaTranslation results directly
let nativeResultJavaType: JavaType =
if wrappedValueResult.outParameters.isEmpty {
.long
} else {
.void
}

let returnType = JavaType.optional(javaType)
return TranslatedResult(
javaType: returnType,
nativeJavaType: wrappedValueResult.nativeJavaType,
annotations: parameterAnnotations,
outParameters: [
OutParameter(name: discriminatorName, type: .array(.byte), allocation: .newArray(.byte, size: 1))
] + wrappedValueResult.outParameters,
conversion: .toOptionalFromIndirectReturn(
discriminatorName: .constant(discriminatorName),
optionalClass: "Optional",
nativeResultJavaType: nativeResultJavaType,
nativeResultJavaType: wrappedValueResult.nativeJavaType,
toValue: wrappedValueResult.conversion,
resultName: resultName
)
Expand Down Expand Up @@ -1449,6 +1455,7 @@ extension JNISwift2JavaGenerator {
)
return TranslatedResult(
javaType: .array(innerResult.javaType),
nativeJavaType: .array(innerResult.javaType),
annotations: annotations,
outParameters: [],
conversion: .placeholder
Expand All @@ -1462,6 +1469,7 @@ extension JNISwift2JavaGenerator {

return TranslatedResult(
javaType: .array(javaType),
nativeJavaType: .array(javaType),
annotations: annotations,
outParameters: [],
conversion: .placeholder,
Expand All @@ -1480,6 +1488,7 @@ extension JNISwift2JavaGenerator {
// We assume this is a JExtract class.
return TranslatedResult(
javaType: .array(javaType),
nativeJavaType: .array(.long),
annotations: annotations,
outParameters: [],
conversion: .method(
Expand Down Expand Up @@ -1564,6 +1573,7 @@ extension JNISwift2JavaGenerator {

return TranslatedResult(
javaType: dictType,
nativeJavaType: .long,
outParameters: [],
conversion: .wrapMemoryAddressUnsafe(.placeholder, dictType),
)
Expand Down Expand Up @@ -1606,6 +1616,7 @@ extension JNISwift2JavaGenerator {

return TranslatedResult(
javaType: setType,
nativeJavaType: .long,
outParameters: [],
conversion: .wrapMemoryAddressUnsafe(.placeholder, setType),
)
Expand Down Expand Up @@ -1682,17 +1693,17 @@ extension JNISwift2JavaGenerator {
var selfParameter: TranslatedParameter?
var selfTypeParameter: TranslatedParameter?
var parameters: [TranslatedParameter]
var resultType: TranslatedResult
var result: TranslatedResult
var exceptions: [JavaExceptionType]

// if the result type implied any annotations,
// propagate them onto the function the result is returned from
var annotations: [JavaAnnotation] {
self.resultType.annotations
self.result.annotations
}

var requiresSwiftArena: Bool {
self.resultType.conversion.requiresSwiftArena
self.result.conversion.requiresSwiftArena
}
}

Expand All @@ -1704,12 +1715,15 @@ extension JNISwift2JavaGenerator {

/// Represent a Swift API result translated to Java.
struct TranslatedResult {
let javaType: JavaType
var javaType: JavaType

/// result type of native function
var nativeJavaType: JavaType

/// Java annotations that should be propagated from the result type onto the method
var annotations: [JavaAnnotation] = []

let outParameters: [OutParameter]
var outParameters: [OutParameter]

/// Represents how to convert the Java native result into a user-facing result.
var conversion: JavaNativeConversionStep
Expand Down Expand Up @@ -1742,10 +1756,6 @@ extension JNISwift2JavaGenerator {
let name: String
let type: JavaType
let allocation: Allocation

var javaParameter: JavaParameter {
JavaParameter(name: self.name, type: self.type)
}
}

/// Represent a Swift closure type in the user facing Java API.
Expand Down
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