jextract: Evaluate IfConfigDecl and add --static-build-config option

Package.swift

@@ -118,7 +118,7 @@ let package = Package(
   ],
   dependencies: [
     swiftJavaJNICoreDep,
-    .package(url: "https://github.com/swiftlang/swift-syntax", from: "602.0.0"),
+    .package(url: "https://github.com/swiftlang/swift-syntax", from: "603.0.0"),
     .package(url: "https://github.com/apple/swift-argument-parser", from: "1.5.0"),
     .package(url: "https://github.com/apple/swift-system", from: "1.4.0"),
     .package(url: "https://github.com/apple/swift-log", from: "1.2.0"),

Plugins/JExtractSwiftPlugin/JExtractSwiftPlugin.swift

@@ -46,7 +46,7 @@ struct JExtractSwiftBuildToolPlugin: SwiftJavaPluginProtocol, BuildToolPlugin {
     // The name of the configuration file SwiftJava.config from the target for
     // which we are generating Swift wrappers for Java classes.
     let configFile = sourceDir.appending(path: "swift-java.config")
-    let configuration = try readConfiguration(sourceDir: sourceDir)
+    let configuration = try readConfiguration(configPath: configFile)
 
     // We use the the usual maven-style structure of "src/[generated|main|test]/java/..."
     // that is common in JVM ecosystem
@@ -71,6 +71,13 @@ struct JExtractSwiftBuildToolPlugin: SwiftJavaPluginProtocol, BuildToolPlugin {
       //       We'll have to make up some caching inside the tool so we don't re-parse files which have not changed etc.
     ]
 
+    if let staticBuildConfig = configuration?.staticBuildConfigurationFile {
+      guard let resolvedURL = URL(string: staticBuildConfig, relativeTo: configFile) else {
+        fatalError("Could not resolve 'staticBuildConfigurationFile' url")
+      }
+      arguments += ["--static-build-config", resolvedURL.absoluteURL.path(percentEncoded: false)]
+    }
+
     let dependentConfigFilesArguments = dependentConfigFiles.flatMap { moduleAndConfigFile in
       let (moduleName, configFile) = moduleAndConfigFile
       return [

Sources/JExtractSwiftLib/Convenience/SwiftSyntax+Extensions.swift

@@ -229,8 +229,10 @@ extension DeclSyntaxProtocol {
       } else {
         "var"
       }
+    case .unexpectedCodeDecl(let node):
+      node.trimmedDescription
     case .usingDecl(let node):
-      node.nameForDebug
+      node.trimmedDescription
     }
   }
 

Sources/JExtractSwiftLib/JExtractDefaultBuildConfiguration.swift

@@ -0,0 +1,101 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 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 Foundation
+import SwiftIfConfig
+import SwiftSyntax
+
+/// A default, fixed build configuration during static analysis for interface extraction.
+struct JExtractDefaultBuildConfiguration: BuildConfiguration {
+  private var base: StaticBuildConfiguration
+
+  init() {
+    let decoder = JSONDecoder()
+    base = try! decoder.decode(StaticBuildConfiguration.self, from: printStaticBuildConfigOutput)
+  }
+
+  func isCustomConditionSet(name: String) throws -> Bool {
+    base.isCustomConditionSet(name: name)
+  }
+
+  func hasFeature(name: String) throws -> Bool {
+    base.hasFeature(name: name)
+  }
+
+  func hasAttribute(name: String) throws -> Bool {
+    base.hasAttribute(name: name)
+  }
+
+  func canImport(importPath: [(TokenSyntax, String)], version: CanImportVersion) throws -> Bool {
+    try base.canImport(importPath: importPath, version: version)
+  }
+
+  func isActiveTargetOS(name: String) throws -> Bool {
+    true
+  }
+
+  func isActiveTargetArchitecture(name: String) throws -> Bool {
+    true
+  }
+
+  func isActiveTargetEnvironment(name: String) throws -> Bool {
+    true
+  }
+
+  func isActiveTargetRuntime(name: String) throws -> Bool {
+    true
+  }
+
+  func isActiveTargetPointerAuthentication(name: String) throws -> Bool {
+    true
+  }
+
+  func isActiveTargetObjectFormat(name: String) throws -> Bool {
+    true
+  }
+
+  var targetPointerBitWidth: Int {
+    base.targetPointerBitWidth
+  }
+
+  var targetAtomicBitWidths: [Int] {
+    base.targetAtomicBitWidths
+  }
+
+  var endianness: Endianness {
+    base.endianness
+  }
+
+  var languageVersion: VersionTuple {
+    base.languageVersion
+  }
+
+  var compilerVersion: VersionTuple {
+    base.compilerVersion
+  }
+}
+
+private let shared = JExtractDefaultBuildConfiguration()
+
+extension BuildConfiguration where Self == JExtractDefaultBuildConfiguration {
+  static var jextractDefault: JExtractDefaultBuildConfiguration {
+    shared
+  }
+}
+
+// $ swift frontend -print-static-build-config -target aarch64-unknown-linux-gnu
+private let printStaticBuildConfigOutput = Data(
+  #"{"attributes":["GKInspectable","noDerivative","objcMembers","discardableResult","const","available","usableFromInline","preconcurrency","nonisolated","retroactive","frozen","unsafe","propertyWrapper","lifetime","_extern","inline","abi","storageRestrictions","_opaqueReturnTypeOf","objc","constInitialized","autoclosure","escaping","unchecked","requires_stored_property_inits","convention","attached","nonexhaustive","dynamicCallable","reasync","dynamicMemberLookup","NSCopying","transpose","warn_unqualified_access","c","globalActor","isolated","_local","rethrows","exclusivity","backDeployed","UIApplicationMain","main","nonobjc","resultBuilder","Sendable","_noMetadata","IBDesignable","IBOutlet","export","IBSegueAction","IBAction","derivative","NSApplicationMain","inlinable","concurrent","IBInspectable","NSManaged","_addressable","differentiable"],"compilerVersion":{"components":[6,3]},"customConditions":[],"endianness":"little","features":["BuiltinCreateAsyncTaskWithExecutor","BuiltinCreateAsyncTaskName","Macros","ValueGenericsNameLookup","FreestandingExpressionMacros","AssociatedTypeAvailability","NoncopyableGenerics2","BuiltinInterleave","OptionalIsolatedParameters","BuiltinAddressOfRawLayout","InoutLifetimeDependence","ExtensionMacros","BuiltinBuildMainExecutor","BuiltinStoreRaw","InheritActorContext","IsolatedAny","BuiltinExecutor","LayoutPrespecialization","NonexhaustiveAttribute","InlineAlways","BuiltinCreateTaskGroupWithFlags","ValueGenerics","InlineArrayTypeSugar","BuiltinCreateTask","NonescapableTypes","RetroactiveAttribute","BuiltinTaskRunInline","BuiltinBuildComplexEqualityExecutor","MemorySafetyAttributes","BuiltinBuildExecutor","ModuleSelector","ParameterPacks","MarkerProtocol","ConformanceSuppression","BitwiseCopyable","AddressOfProperty2","UnsafeInheritExecutor","BuiltinCreateAsyncTaskOwnedTaskExecutor","SpecializeAttributeWithAvailability","BuiltinJob","AlwaysInheritActorContext","AsyncExecutionBehaviorAttributes","AsyncSequenceFailure","BorrowingSwitch","PrimaryAssociatedTypes2","NewCxxMethodSafetyHeuristics","ExtensionMacroAttr","BuiltinStackAlloc","TypedThrows","BuiltinContinuation","BuiltinUnprotectedAddressOf","BuiltinSelect","ImplicitSelfCapture","MoveOnlyPartialConsumption","Actors","GeneralizedIsSameMetaTypeBuiltin","MoveOnly","GlobalActors","BuiltinCreateAsyncDiscardingTaskInGroupWithExecutor","NonfrozenEnumExhaustivity","RethrowsProtocol","IsolatedDeinit","BuiltinUnprotectedStackAlloc","BuiltinCreateAsyncTaskInGroupWithExecutor","BuiltinTaskGroupWithArgument","NoAsyncAvailability","ObjCImplementation","AttachedMacros","FreestandingMacros","AsyncAwait","EffectfulProp","BuiltinConcurrencyStackNesting","BuiltinCreateAsyncTaskInGroup","ConcurrentFunctions","BuiltinHopToActor","BuiltinIntLiteralAccessors","BodyMacros","BuiltinVectorsExternC","BuiltinCreateAsyncDiscardingTaskInGroup","RawIdentifiers","NonescapableAccessorOnTrivial","UnavailableFromAsync","IsolatedAny2","LexicalLifetimes","SendableCompletionHandlers","BuiltinAssumeAlignment","AssociatedTypeImplements","Sendable","ABIAttributeSE0479","BuiltinBuildTaskExecutorRef","LifetimeDependenceMutableAccessors","BitwiseCopyable2","IsolatedConformances","ExpressionMacroDefaultArguments","NoncopyableGenerics","SendingArgsAndResults","MoveOnlyResilientTypes","BuiltinEmplaceTypedThrows"],"languageMode":{"components":[5,10]},"targetArchitectures":["arm64"],"targetAtomicBitWidths":[128,64,32,16,8],"targetEnvironments":[],"targetOSs":["Linux"],"targetObjectFileFormats":["ELF"],"targetPointerAuthenticationSchemes":["_none"],"targetPointerBitWidth":64,"targetRuntimes":["_Native","_multithreaded"]}"#
+    .utf8
+)

Sources/JExtractSwiftLib/Swift2Java.swift

@@ -34,7 +34,6 @@ public struct SwiftToJava {
     }
 
     let translator = Swift2JavaTranslator(config: config)
-    translator.log.logLevel = config.logLevel ?? .info
     let log = translator.log
 
     if config.javaPackage == nil || config.javaPackage!.isEmpty {

Sources/JExtractSwiftLib/Swift2JavaTranslator.swift

@@ -14,6 +14,7 @@
 
 import Foundation
 import SwiftBasicFormat
+import SwiftIfConfig
 import SwiftJavaConfigurationShared
 import SwiftJavaJNICore
 import SwiftParser
@@ -27,6 +28,9 @@ public final class Swift2JavaTranslator {
 
   let config: Configuration
 
+  /// The build configuration used to resolve #if conditional compilation blocks.
+  let buildConfig: any BuildConfiguration
+
   /// The name of the Swift module being translated.
   let swiftModuleName: String
 
@@ -70,6 +74,19 @@ public final class Swift2JavaTranslator {
     self.log = Logger(label: "translator", logLevel: config.logLevel ?? .info)
     self.config = config
     self.swiftModuleName = swiftModule
+
+    if let staticBuildConfigPath = config.staticBuildConfigurationFile {
+      do {
+        let data = try Data(contentsOf: URL(fileURLWithPath: staticBuildConfigPath))
+        let decoder = JSONDecoder()
+        self.buildConfig = try decoder.decode(StaticBuildConfiguration.self, from: data)
+        self.log.info("Using custom static build configuration from: \(staticBuildConfigPath)")
+      } catch {
+        fatalError("Failed to load static build configuration from '\(staticBuildConfigPath)': \(error)")
+      }
+    } else {
+      self.buildConfig = .jextractDefault
+    }
   }
 }
 
@@ -152,6 +169,7 @@ extension Swift2JavaTranslator {
       moduleName: self.swiftModuleName,
       inputs + [dependenciesSource],
       config: self.config,
+      buildConfig: self.buildConfig,
       log: self.log,
     )
     self.lookupContext = SwiftTypeLookupContext(symbolTable: symbolTable)

Sources/JExtractSwiftLib/Swift2JavaVisitor.swift

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
+import SwiftIfConfig
 import SwiftJavaConfigurationShared
 import SwiftParser
 import SwiftSyntax
@@ -70,7 +71,8 @@ final class Swift2JavaVisitor {
       self.visit(subscriptDecl: node, in: parent)
     case .enumCaseDecl(let node):
       self.visit(enumCaseDecl: node, in: parent)
-
+    case .ifConfigDecl(let node):
+      self.visit(ifConfigDecl: node, in: parent, sourceFilePath: sourceFilePath)
     default:
       break
     }
@@ -366,6 +368,30 @@ final class Swift2JavaVisitor {
     }
   }
 
+  private func visit(
+    ifConfigDecl node: IfConfigDeclSyntax,
+    in parent: ImportedNominalType?,
+    sourceFilePath: String
+  ) {
+    let (clause, _) = node.activeClause(in: translator.buildConfig)
+    if let clause, let elements = clause.elements {
+      switch elements {
+      case .statements(let codeBlock):
+        for codeItem in codeBlock {
+          if let declNode = codeItem.item.as(DeclSyntax.self) {
+            self.visit(decl: declNode, in: parent, sourceFilePath: sourceFilePath)
+          }
+        }
+      case .decls(let memberBlock):
+        for memberItem in memberBlock {
+          self.visit(decl: memberItem.decl, in: parent, sourceFilePath: sourceFilePath)
+        }
+      default:
+        break
+      }
+    }
+  }
+
   private func importAccessor(
     from node: DeclSyntax,
     in typeContext: ImportedNominalType?,

Sources/JExtractSwiftLib/SwiftTypes/SwiftParsedModuleSymbolTableBuilder.swift

@@ -12,6 +12,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+import SwiftIfConfig
 import SwiftSyntax
 
 struct SwiftParsedModuleSymbolTableBuilder {
@@ -23,6 +24,9 @@ struct SwiftParsedModuleSymbolTableBuilder {
   /// Imported modules to resolve type syntax.
   let importedModules: [String: SwiftModuleSymbolTable]
 
+  /// The build configuration used to resolve #if conditional compilation blocks.
+  let buildConfig: any BuildConfiguration
+
   /// Extension decls their extended type hasn't been resolved.
   var unresolvedExtensions: [ExtensionDeclSyntax]
 
@@ -31,6 +35,7 @@ struct SwiftParsedModuleSymbolTableBuilder {
     requiredAvailablityOfModuleWithName: String? = nil,
     alternativeModules: SwiftModuleSymbolTable.AlternativeModuleNamesData? = nil,
     importedModules: [String: SwiftModuleSymbolTable],
+    buildConfig: any BuildConfiguration = .jextractDefault,
     log: Logger? = nil
   ) {
     self.log = log
@@ -40,6 +45,7 @@ struct SwiftParsedModuleSymbolTableBuilder {
       alternativeModules: alternativeModules
     )
     self.importedModules = importedModules
+    self.buildConfig = buildConfig
     self.unresolvedExtensions = []
   }
 
@@ -56,17 +62,25 @@ extension SwiftParsedModuleSymbolTableBuilder {
   ) {
     // Find top-level type declarations.
     for statement in sourceFile.statements {
-      // We only care about declarations.
-      guard case .decl(let decl) = statement.item else {
-        continue
-      }
+      self.handle(codeBlockItem: statement.item, sourceFilePath: sourceFilePath)
+    }
+  }
 
-      if let nominalTypeNode = decl.asNominal {
-        self.handle(sourceFilePath: sourceFilePath, nominalTypeDecl: nominalTypeNode, parent: nil)
-      }
-      if let extensionNode = decl.as(ExtensionDeclSyntax.self) {
-        self.handle(extensionDecl: extensionNode, sourceFilePath: sourceFilePath)
-      }
+  mutating func handle(
+    codeBlockItem node: CodeBlockItemSyntax.Item,
+    sourceFilePath: String
+  ) {
+    // We only care about declarations.
+    guard case .decl(let decl) = node else {
+      return
+    }
+
+    if let nominalTypeNode = decl.asNominal {
+      self.handle(sourceFilePath: sourceFilePath, nominalTypeDecl: nominalTypeNode, parent: nil)
+    } else if let extensionNode = decl.as(ExtensionDeclSyntax.self) {
+      self.handle(extensionDecl: extensionNode, sourceFilePath: sourceFilePath)
+    } else if let ifConfigNode = decl.as(IfConfigDeclSyntax.self) {
+      self.handle(ifConfig: ifConfigNode, sourceFilePath: sourceFilePath)
     }
   }
 
@@ -152,6 +166,23 @@ extension SwiftParsedModuleSymbolTableBuilder {
     return true
   }
 
+  mutating func handle(
+    ifConfig node: IfConfigDeclSyntax,
+    sourceFilePath: String
+  ) {
+    let (clause, _) = node.activeClause(in: buildConfig)
+    if let clause, let elements = clause.elements {
+      switch elements {
+      case .statements(let codeBlock):
+        for codeItem in codeBlock {
+          self.handle(codeBlockItem: codeItem.item, sourceFilePath: sourceFilePath)
+        }
+      default:
+        break
+      }
+    }
+  }
+
   /// Finalize the symbol table and return it.
   mutating func finalize() -> SwiftModuleSymbolTable {
     // Handle the unresolved extensions.

Sources/JExtractSwiftLib/SwiftTypes/SwiftSymbolTable.swift

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 import CodePrinting
+import SwiftIfConfig
 import SwiftJavaConfigurationShared
 import SwiftParser
 import SwiftSyntax
@@ -69,6 +70,7 @@ extension SwiftSymbolTable {
     moduleName: String,
     _ inputFiles: some Collection<SwiftJavaInputFile>,
     config: Configuration?,
+    buildConfig: any BuildConfiguration = .jextractDefault,
     log: Logger,
   ) -> SwiftSymbolTable {
 
@@ -104,6 +106,7 @@ extension SwiftSymbolTable {
           var stubBuilder = SwiftParsedModuleSymbolTableBuilder(
             moduleName: stubModuleName,
             importedModules: ["Swift": importedModules["Swift"]!],
+            buildConfig: buildConfig,
           )
           stubBuilder.handle(sourceFile: sourceFile, sourceFilePath: "\(stubModuleName)_stub.swift")
           let stubModule = stubBuilder.finalize()
@@ -122,6 +125,7 @@ extension SwiftSymbolTable {
     var builder = SwiftParsedModuleSymbolTableBuilder(
       moduleName: moduleName,
       importedModules: importedModules,
+      buildConfig: buildConfig,
       log: log,
     )
     // First, register top-level and nested nominal types to the symbol table.

Sources/SwiftJavaConfigurationShared/Configuration.swift

@@ -132,6 +132,10 @@ public struct Configuration: Codable {
   /// ```
   public var specialize: [String: SpecializationConfigEntry]?
 
+  /// If set, use this JSON file as the static build configuration for jextract.
+  /// This allows users to provide a custom StaticBuildConfiguration for #if resolution.
+  public var staticBuildConfigurationFile: String?
+
   // ==== wrap-java ---------------------------------------------------------
 
   /// The Java class path that should be passed along to the swift-java tool.