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[JExtract/JNI] Omit unsupported types instead of crashing #313

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Merged
merged 5 commits into from
Jul 14, 2025
Merged

[JExtract/JNI] Omit unsupported types instead of crashing #313

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3cab67b
add support for variables
madsodgaard Jul 12, 2025
1d771bd
prefix boolean variables with `is` to match Java conventions
madsodgaard Jul 12, 2025
5211bee
add variable tests
madsodgaard Jul 12, 2025
3fdb127
throw errors instead of crashing on unsupported type
madsodgaard Jul 13, 2025
87a0e4f
PR feedback
madsodgaard Jul 13, 2025
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1 change: 1 addition & 0 deletions Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/MySwiftClass.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ public class MySwiftClass {
let x: Int64
let y: Int64

public let byte: UInt8 = 0
public let constant: Int64 = 100
public var mutable: Int64 = 0
public var product: Int64 {
Expand Down
14 changes: 11 additions & 3 deletions Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift
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Expand Up @@ -176,6 +176,11 @@ extension JNISwift2JavaGenerator {
}

private func printFunctionBinding(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
guard let translatedDecl = translatedDecl(for: decl) else {
// Failed to translate. Skip.
return
}

if decl.isStatic || decl.isInitializer || !decl.hasParent {
printStaticFunctionBinding(&printer, decl)
} else {
Expand All @@ -196,7 +201,7 @@ extension JNISwift2JavaGenerator {
/// and passes it down to another native function along with the arguments
/// to call the Swift implementation.
private func printMemberMethodBindings(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
let translatedDecl = translatedDecl(for: decl)
let translatedDecl = translatedDecl(for: decl)!

printDeclDocumentation(&printer, decl)
printer.printBraceBlock("public \(renderFunctionSignature(decl))") { printer in
Expand All @@ -220,7 +225,10 @@ extension JNISwift2JavaGenerator {
}

private func printInitializerBindings(_ printer: inout CodePrinter, _ decl: ImportedFunc, type: ImportedNominalType) {
let translatedDecl = translatedDecl(for: decl)
guard let translatedDecl = translatedDecl(for: decl) else {
// Failed to translate. Skip.
return
}

printDeclDocumentation(&printer, decl)
printer.printBraceBlock("public static \(renderFunctionSignature(decl))") { printer in
Expand Down Expand Up @@ -275,7 +283,7 @@ extension JNISwift2JavaGenerator {
/// `func method(x: Int, y: Int) -> Int` becomes
/// `long method(long x, long y)`
private func renderFunctionSignature(_ decl: ImportedFunc) -> String {
let translatedDecl = translatedDecl(for: decl)
let translatedDecl = translatedDecl(for: decl)!
let resultType = translatedDecl.translatedFunctionSignature.resultType
var parameters = translatedDecl.translatedFunctionSignature.parameters.map(\.asParameter)

Expand Down
38 changes: 24 additions & 14 deletions Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaTranslation.swift
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Expand Up @@ -17,13 +17,19 @@ import JavaTypes
extension JNISwift2JavaGenerator {
func translatedDecl(
for decl: ImportedFunc
) -> TranslatedFunctionDecl {
) -> TranslatedFunctionDecl? {
if let cached = translatedDecls[decl] {
return cached
}

let translation = JavaTranslation(swiftModuleName: self.swiftModuleName)
let translated = translation.translate(decl)
let translated: TranslatedFunctionDecl?
do {
let translation = JavaTranslation(swiftModuleName: swiftModuleName)
translated = try translation.translate(decl)
} catch {
self.logger.info("Failed to translate: '\(decl.swiftDecl.qualifiedNameForDebug)'; \(error)")
translated = nil
}

translatedDecls[decl] = translated
return translated
Expand All @@ -32,8 +38,8 @@ extension JNISwift2JavaGenerator {
struct JavaTranslation {
let swiftModuleName: String

func translate(_ decl: ImportedFunc) -> TranslatedFunctionDecl {
let translatedFunctionSignature = translate(functionSignature: decl.functionSignature)
func translate(_ decl: ImportedFunc) throws -> TranslatedFunctionDecl {
let translatedFunctionSignature = try translate(functionSignature: decl.functionSignature)
// Types with no parent will be outputted inside a "module" class.
let parentName = decl.parentType?.asNominalType?.nominalTypeDecl.qualifiedName ?? swiftModuleName

Expand All @@ -51,31 +57,31 @@ extension JNISwift2JavaGenerator {
)
}

func translate(functionSignature: SwiftFunctionSignature, isInitializer: Bool = false) -> TranslatedFunctionSignature {
let parameters = functionSignature.parameters.enumerated().map { idx, param in
func translate(functionSignature: SwiftFunctionSignature, isInitializer: Bool = false) throws -> TranslatedFunctionSignature {
let parameters = try functionSignature.parameters.enumerated().map { idx, param in
let parameterName = param.parameterName ?? "arg\(idx))"
return translate(swiftParam: param, parameterName: parameterName)
return try translate(swiftParam: param, parameterName: parameterName)
}

return TranslatedFunctionSignature(
return try TranslatedFunctionSignature(
parameters: parameters,
resultType: translate(swiftType: functionSignature.result.type)
)
}

func translate(swiftParam: SwiftParameter, parameterName: String) -> JavaParameter {
return JavaParameter(
func translate(swiftParam: SwiftParameter, parameterName: String) throws -> JavaParameter {
return try JavaParameter(
name: parameterName,
type: translate(swiftType: swiftParam.type)
)
}

func translate(swiftType: SwiftType) -> JavaType {
func translate(swiftType: SwiftType) throws -> JavaType {
switch swiftType {
case .nominal(let nominalType):
if let knownType = nominalType.nominalTypeDecl.knownTypeKind {
guard let javaType = translate(knownType: knownType) else {
fatalError("unsupported known type: \(knownType)")
throw JavaTranslationError.unsupportedSwiftType(swiftType)
}
return javaType
}
Expand All @@ -86,7 +92,7 @@ extension JNISwift2JavaGenerator {
return .void

case .metatype, .optional, .tuple, .function, .existential, .opaque:
fatalError("unsupported type: \(self)")
throw JavaTranslationError.unsupportedSwiftType(swiftType)
}
}

Expand Down Expand Up @@ -127,4 +133,8 @@ extension JNISwift2JavaGenerator {
let parameters: [JavaParameter]
let resultType: JavaType
}

enum JavaTranslationError: Error {
case unsupportedSwiftType(SwiftType)
}
}
17 changes: 13 additions & 4 deletions Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,11 @@ extension JNISwift2JavaGenerator {
}

private func printInitializerThunk(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
let translatedDecl = translatedDecl(for: decl)
guard let translatedDecl = translatedDecl(for: decl) else {
// Failed to translate. Skip.
return
}

let typeName = translatedDecl.parentName

printCDecl(
Expand Down Expand Up @@ -146,6 +150,11 @@ extension JNISwift2JavaGenerator {
_ printer: inout CodePrinter,
_ decl: ImportedFunc
) {
guard let _ = translatedDecl(for: decl) else {
// Failed to translate. Skip.
return
}

// Free functions does not have a parent
if decl.isStatic || !decl.hasParent {
self.printSwiftStaticFunctionThunk(&printer, decl)
Expand All @@ -155,7 +164,7 @@ extension JNISwift2JavaGenerator {
}

private func printSwiftStaticFunctionThunk(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
let translatedDecl = self.translatedDecl(for: decl)
let translatedDecl = self.translatedDecl(for: decl)!

printCDecl(
&printer,
Expand All @@ -172,7 +181,7 @@ extension JNISwift2JavaGenerator {
}

private func printSwiftMemberFunctionThunk(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
let translatedDecl = self.translatedDecl(for: decl)
let translatedDecl = self.translatedDecl(for: decl)!
let swiftParentName = decl.parentType!.asNominalTypeDeclaration!.qualifiedName

printCDecl(
Expand All @@ -199,7 +208,7 @@ extension JNISwift2JavaGenerator {
_ decl: ImportedFunc,
calleeName: String
) {
let translatedDecl = self.translatedDecl(for: decl)
let translatedDecl = self.translatedDecl(for: decl)!
let swiftReturnType = decl.functionSignature.result.type

let tryClause: String = decl.isThrowing ? "try " : ""
Expand Down
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