@@ -106,6 +106,24 @@ In the case of formatting issues, `git add` the formatting changes and attempt t
 
 Some documentation is generated from source and checked in, so CI can catch it drifting out of date. If you changed `Configuration.swift` or a CLI command's flags/help text, run `scripts/generate-docs.sh` and commit the generated changes.
 
+### Developing against local dependency checkouts
+
+swift-java depends on [swift-java-jni-core](https://github.com/swiftlang/swift-java-jni-core) and [swift-binding-generator-core](https://github.com/swiftlang/swift-binding-generator-core) (home of the `SwiftExtract` library) from their `main` branches. To develop against local checkouts instead, clone the repositories next to your swift-java checkout and point the corresponding environment variables at them:
+
+```bash
+export PROJECT_ROOT=~/code # the directory containing your checkouts
+cd $PROJECT_ROOT
+ls
+> swift-java
+> swift-java-jni-core
+> swift-binding-generator-core
+> # ...and all the others here
+
+export SWIFT_JAVA_JNI_CORE_PATH=$PROJECT_ROOT/swift-java-jni-core
+export SWIFT_BINDING_GENERATOR_CORE_PATH=$PROJECT_ROOT/swift-binding-generator-core
+swift build
+```
+
 ## How to contribute your work
 
 Please open a pull request at https://github.com/swiftlang/swift-java. Make sure the CI passes, and then wait for code review.
 
@@ -11,6 +11,13 @@ if let localPath = Context.environment["SWIFT_JAVA_JNI_CORE_PATH"] {
   swiftJavaJNICoreDep = .package(url: "https://github.com/swiftlang/swift-java-jni-core", branch: "main")
 }
 
+let swiftBindingGeneratorCoreDep: Package.Dependency
+if let localPath = Context.environment["SWIFT_BINDING_GENERATOR_CORE_PATH"] {
+  swiftBindingGeneratorCoreDep = .package(path: localPath)
+} else {
+  swiftBindingGeneratorCoreDep = .package(url: "https://github.com/swiftlang/swift-binding-generator-core", branch: "main")
+}
+
 // Set SWIFTJAVA_DOCC_PLUGIN_INSTALL=1 to install the docc-plugin automatically,
 // or DOCC_PLUGIN_PATH=<path> to point at a local checkout.
 // This is a workaround because swift-subprocess includes the plugin explicitly,
@@ -59,11 +66,6 @@ let package = Package(
       targets: ["SwiftJavaConfigurationShared"]
     ),
 
-    .library(
-      name: "SwiftExtractConfigurationShared",
-      targets: ["SwiftExtractConfigurationShared"]
-    ),
-
     .library(
       name: "JavaUtil",
       targets: ["JavaUtil"]
@@ -129,11 +131,6 @@ let package = Package(
       targets: ["SwiftRuntimeFunctions"]
     ),
 
-    .library(
-      name: "SwiftExtract",
-      targets: ["SwiftExtract"]
-    ),
-
     .library(
       name: "CodePrinting",
       targets: ["CodePrinting"]
@@ -166,6 +163,7 @@ let package = Package(
   ],
   dependencies: [
     swiftJavaJNICoreDep,
+    swiftBindingGeneratorCoreDep,
     .package(url: "https://github.com/swiftlang/swift-syntax", from: "603.0.0"),
     .package(url: "https://github.com/apple/swift-argument-parser", from: "1.8.0"),
     .package(url: "https://github.com/apple/swift-system", from: "1.4.0"),
@@ -304,14 +302,10 @@ let package = Package(
     .target(
       name: "SwiftJavaConfigurationShared",
       dependencies: [
-        "SwiftExtractConfigurationShared"
+        .product(name: "SwiftExtractConfigurationShared", package: "swift-binding-generator-core")
       ]
     ),
 
-    .target(
-      name: "SwiftExtractConfigurationShared"
-    ),
-
     .target(
       name: "SwiftJavaShared"
     ),
@@ -352,6 +346,7 @@ let package = Package(
         .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
         .product(name: "ArgumentParser", package: "swift-argument-parser"),
         .product(name: "SystemPackage", package: "swift-system"),
+        .product(name: "SwiftExtract", package: "swift-binding-generator-core"),
         "SwiftJava",
         "JavaUtilJar",
         "JavaNet",
@@ -375,32 +370,6 @@ let package = Package(
       ]
     ),
 
-    .target(
-      name: "SwiftExtract",
-      dependencies: [
-        .product(name: "SwiftBasicFormat", package: "swift-syntax"),
-        .product(name: "SwiftIfConfig", package: "swift-syntax"),
-        .product(name: "SwiftLexicalLookup", package: "swift-syntax"),
-        .product(name: "SwiftParser", package: "swift-syntax"),
-        .product(name: "SwiftSyntax", package: "swift-syntax"),
-        .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
-        "SwiftExtractConfigurationShared",
-      ],
-      path: "Sources/SwiftExtract",
-      resources: [
-        // Holds the `dummy.json` placeholder so SwiftPM emits a `Bundle.module`
-        // for this target. The real `static-build-config.json` is generated at
-        // build time by the `_StaticBuildConfigPlugin` build tool below.
-        .process("Resources")
-      ],
-      swiftSettings: [
-        .swiftLanguageMode(.v5)
-      ],
-      plugins: [
-        .plugin(name: "_StaticBuildConfigPlugin")
-      ]
-    ),
-
     .target(
       name: "JExtractSwiftLib",
       dependencies: [
@@ -412,7 +381,7 @@ let package = Package(
         .product(name: "ArgumentParser", package: "swift-argument-parser"),
         .product(name: "OrderedCollections", package: "swift-collections"),
         .product(name: "SwiftJavaJNICore", package: "swift-java-jni-core"),
-        "SwiftExtract",
+        .product(name: "SwiftExtract", package: "swift-binding-generator-core"),
         "SwiftJavaShared",
         "SwiftJavaConfigurationShared",
         "CodePrinting",
@@ -423,14 +392,6 @@ let package = Package(
       ]
     ),
 
-    .executableTarget(
-      name: "StaticBuildConfigPluginExecutable",
-      dependencies: [
-        .product(name: "Subprocess", package: "swift-subprocess"),
-        .product(name: "SwiftIfConfig", package: "swift-syntax"),
-      ]
-    ),
-
     // Dev-time tool: regenerates the "Supported configuration options" table in
     // `Sources/SwiftJavaDocumentation/Documentation.docc/SwiftJavaConfigFile.md`
     // straight from the doc comments on `Configuration.swift` and the enums it
@@ -448,14 +409,6 @@ let package = Package(
       path: "Sources/GenerateConfigDocs"
     ),
 
-    .plugin(
-      name: "_StaticBuildConfigPlugin",
-      capability: .buildTool(),
-      dependencies: [
-        "StaticBuildConfigPluginExecutable"
-      ]
-    ),
-
     .plugin(
       name: "JExtractSwiftPlugin",
       capability: .buildTool(),
@@ -512,23 +465,14 @@ let package = Package(
       name: "JExtractSwiftTests",
       dependencies: [
         "JExtractSwiftLib",
-        "SwiftExtract",
+        .product(name: "SwiftExtract", package: "swift-binding-generator-core"),
         "CodePrinting",
       ],
       swiftSettings: [
         .swiftLanguageMode(.v5)
       ]
     ),
 
-    .testTarget(
-      name: "SwiftExtractTests",
-      dependencies: [
-        "SwiftExtract",
-        .product(name: "SwiftSyntax", package: "swift-syntax"),
-        .product(name: "SwiftParser", package: "swift-syntax"),
-      ]
-    ),
-
     .testTarget(
       name: "CodePrintingTests",
       dependencies: [
 
@@ -0,0 +1,14 @@
+DO NOT EDIT THESE FILES IN THIS REPOSITORY.
+
+The files in this directory are vendored, byte-identical copies of:
+
+    https://github.com/swiftlang/swift-binding-generator-core
+    Sources/SwiftExtractConfigurationShared/
+
+They exist because SwiftPM package plugins cannot take sources from a package
+dependency, so the plugins in this repository compile these files directly.
+
+Make any changes in swift-binding-generator-core instead, and then copy the
+updated files here. The swift-java compatibility CI job in
+swift-binding-generator-core diffs these copies against its own sources and
+will flag any drift.
@@ -12,20 +12,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-extension Dictionary {
-  /// Same values, corresponding to mapped keys.
-  public func mapKeys<Transformed>(
-    _ transform: (Key) throws -> Transformed
-  ) rethrows -> [Transformed: Value] {
-    .init(
-      uniqueKeysWithValues: try map {
-        (try transform($0.key), $0.value)
-      }
-    )
-  }
-
-}
-
 extension Collection {
   package typealias IsLastElement = Bool
   package var withIsLast: any Collection<(Element, IsLastElement)> {
@@ -39,13 +25,3 @@ extension Collection {
     }
   }
 }
-
-extension Collection where Element == Int {
-  var sum: Int {
-    var s = 0
-    for i in self {
-      s += i
-    }
-    return s
-  }
-}
@@ -0,0 +1,92 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftSyntax
+
+extension DeclSyntaxProtocol {
+  /// Signature part of the declaration. I.e. without body or member block.
+  package var signatureString: String {
+    switch DeclSyntax(self.detached).as(DeclSyntaxEnum.self) {
+    case .functionDecl(let node):
+      node.with(\.body, nil).triviaSanitizedDescription
+    case .initializerDecl(let node):
+      node.with(\.body, nil).triviaSanitizedDescription
+    case .classDecl(let node):
+      node.with(\.memberBlock, "").triviaSanitizedDescription
+    case .structDecl(let node):
+      node.with(\.memberBlock, "").triviaSanitizedDescription
+    case .protocolDecl(let node):
+      node.with(\.memberBlock, "").triviaSanitizedDescription
+    case .accessorDecl(let node):
+      node.with(\.body, nil).triviaSanitizedDescription
+    case .subscriptDecl(let node):
+      node.with(\.accessorBlock, nil).triviaSanitizedDescription
+    case .variableDecl(let node):
+      node
+        .with(
+          \.bindings,
+          PatternBindingListSyntax(
+            node.bindings.map {
+              $0.detached
+                .with(\.accessorBlock, nil)
+                .with(\.initializer, nil)
+            }
+          ),
+        )
+        .triviaSanitizedDescription
+    case .enumCaseDecl(let node):
+      node.triviaSanitizedDescription
+    default:
+      fatalError("unimplemented \(self.kind)")
+    }
+  }
+
+
+  /// Syntax text but without unnecessary trivia.
+  ///
+  /// Connective trivia are condensed into a single whitespace, but no space
+  /// after opening or before closing parentheses
+  var triviaSanitizedDescription: String {
+    let visitor = TriviaSanitizingDescriptionVisitor(viewMode: .sourceAccurate)
+    visitor.walk(self.trimmed)
+    return visitor.result
+  }
+}
+
+class TriviaSanitizingDescriptionVisitor: SyntaxVisitor {
+  var result: String = ""
+
+  var prevTokenKind: TokenKind = .endOfFile
+  var prevHadTrailingSpace: Bool = false
+
+  override func visit(_ node: TokenSyntax) -> SyntaxVisitorContinueKind {
+    let tokenKind = node.tokenKind
+    switch (prevTokenKind, tokenKind) {
+    case // No whitespace after open parentheses.
+    (.leftAngle, _), (.leftParen, _), (.leftSquare, _), (.endOfFile, _),
+      // No whitespace before close parentheses.
+      (_, .rightAngle), (_, .rightParen), (_, .rightSquare):
+      break
+    default:
+      if prevHadTrailingSpace || !node.leadingTrivia.isEmpty {
+        result += " "
+      }
+    }
+    result += node.text
+    prevTokenKind = tokenKind
+    prevHadTrailingSpace = !node.trailingTrivia.isEmpty
+
+    return .skipChildren
+  }
+}