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jextract/ffm: Treat underscore labels as empty suffixes in function overloads #735

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Merged
ktoso merged 1 commit into from
May 11, 2026
Merged

jextract/ffm: Treat underscore labels as empty suffixes in function overloads #735

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4 changes: 4 additions & 0 deletions Samples/SwiftJavaExtractFFMSampleApp/Sources/MySwiftLibrary/MySwiftLibrary.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,10 @@ public func globalOverloaded(b: Int) {
p("globalOverloaded(b: \(b))")
}

public func globalOverloaded(_ c: Int) {
p("globalOverloaded(c: \(c))")
}

// ==== Internal helpers

func p(_ msg: String, file: String = #fileID, line: UInt = #line, function: String = #function) {
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3 changes: 2 additions & 1 deletion Samples/SwiftJavaExtractFFMSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java
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Expand Up @@ -85,7 +85,7 @@ static void examples() {
var origBytes = arena.allocateFrom("foobar");
var origDat = Data.init(origBytes, origBytes.byteSize(), arena);
CallTraces.trace("origDat.count = " + origDat.getCount());

var retDat = MySwiftLibrary.globalReceiveReturnData(origDat, arena);
retDat.withUnsafeBytes((retBytes) -> {
var str = retBytes.getString(0);
Expand All @@ -104,6 +104,7 @@ static void examples() {
// Overloaded functions with label-based disambiguation
MySwiftLibrary.globalOverloadedA(100);
MySwiftLibrary.globalOverloadedB(200);
MySwiftLibrary.globalOverloaded(300);

System.out.println("DONE.");
}
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11 changes: 6 additions & 5 deletions Sources/JExtractSwiftLib/JavaIdentifierFactory.swift
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Expand Up @@ -81,11 +81,12 @@ package struct JavaIdentifierFactory {
return ""
default:
guard needsSuffix(for: baseName) else { return "" }
let labels = decl.functionSignature.parameters
.compactMap { $0.argumentLabel }
// A parameterless function that still conflicts (e.g. with a property
// getter) gets a bare "_" so it compiles as a distinct Java method.
guard !labels.isEmpty else { return "_" }
if decl.functionSignature.parameters.isEmpty {
// A parameterless function that still conflicts (e.g. with a property
// getter) gets a bare "_" so it compiles as a distinct Java method.
return "_"
}
let labels = decl.functionSignature.parameters.compactMap(\.argumentLabel)
// Join labels in camelCase: takeValue(a:) → takeValueA
return labels.map { $0.prefix(1).uppercased() + $0.dropFirst() }.joined()
}
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3 changes: 3 additions & 0 deletions Tests/JExtractSwiftTests/MethodImportTests.swift
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Expand Up @@ -530,6 +530,7 @@ final class MethodImportTests {

public func takeValue(a: Swift.String) -> Swift.Int
public func takeValue(b: Swift.String) -> Swift.Int
public func takeValue(_ c: Swift.String) -> Swift.Int
public func uniqueFunc(x: Swift.Int) -> Swift.Int
public func overloaded(a: Swift.Int) -> Swift.Int
public func overloaded(a: Swift.String) -> Swift.Int
Expand All @@ -551,6 +552,7 @@ final class MethodImportTests {
expectedChunks: [
"public static long takeValueA(java.lang.String a)",
"public static long takeValueB(java.lang.String b)",
"public static long takeValue(java.lang.String c)",
]
)
}
Expand Down Expand Up @@ -679,6 +681,7 @@ final class MethodImportTests {
expectedChunks: [
"public static long takeValueA(java.lang.String a)",
"public static long takeValueB(java.lang.String b)",
"public static long takeValue(java.lang.String c)",
]
)
}
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