PoC how we might try to use package traits

Author: ktoso

Package.swift

@@ -1,11 +1,14 @@
-// swift-tools-version: 6.0
+// swift-tools-version: 6.1
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import CompilerPluginSupport
 import PackageDescription
 
 import Foundation
 
+// Package Trait Names 
+let SwiftJavaMacrosSupport: String = "SwiftJavaMacrosSupport"
+
 // Note: the JAVA_HOME environment variable must be set to point to where
 // Java is installed, e.g.,
 //   Library/Java/JavaVirtualMachines/openjdk-21.jdk/Contents/Home.
@@ -196,6 +199,17 @@ let package = Package(
     ),
 
   ],
+
+  traits: [
+    .init(
+      name: SwiftJavaMacrosSupport, 
+      description: "Enable @JavaMethod, @JavaClass and other Swift macros which are used in wrapping Java types"
+    ),
+    .default(enabledTraits: [
+      SwiftJavaMacrosSupport
+    ]) // enabled by default, but downstream libraries may disable macros if they don't use them
+  ],
+
   dependencies: [
     .package(url: "https://github.com/swiftlang/swift-syntax", from: "601.0.1"),
     .package(url: "https://github.com/apple/swift-argument-parser", from: "1.5.0"),
@@ -208,6 +222,7 @@ let package = Package(
     // Benchmarking
     .package(url: "https://github.com/ordo-one/package-benchmark", .upToNextMajor(from: "1.4.0")),
   ],
+
   targets: [
     .target(
       name: "SwiftJavaDocumentation",
@@ -220,8 +235,8 @@ let package = Package(
     .macro(
       name: "SwiftJavaMacros",
       dependencies: [
-        .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
-        .product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
+        .product(name: "SwiftSyntaxMacros", package: "swift-syntax", condition: .when(traits: [SwiftJavaMacrosSupport])),
+        .product(name: "SwiftCompilerPlugin", package: "swift-syntax", condition: .when(traits: [SwiftJavaMacrosSupport])),
       ],
       swiftSettings: [
         .swiftLanguageMode(.v5)
@@ -237,10 +252,10 @@ let package = Package(
     .target(
       name: "SwiftJava",
       dependencies: [
-        "CSwiftJavaJNI",
-        "SwiftJavaMacros",
-        "JavaTypes",
-        "SwiftJavaConfigurationShared", // for Configuration reading at runtime
+        .byName(name: "CSwiftJavaJNI"),
+        .byName(name: "JavaTypes"),
+        .byName(name: "SwiftJavaMacros", condition: .when(traits: [SwiftJavaMacrosSupport])),
+        .byName(name: "SwiftJavaConfigurationShared"), // for Configuration reading at runtime
       ],
       exclude: ["swift-java.config"],
       swiftSettings: [

Sources/JavaStdlib/JavaIO/generated/BufferedInputStream.swift

@@ -2,6 +2,7 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaClass("java.io.BufferedInputStream")
 open class BufferedInputStream: InputStream {
   @JavaMethod
@@ -37,3 +38,4 @@ open class BufferedInputStream: InputStream {
   @JavaMethod
   open override func markSupported() -> Bool
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/Charset.swift

@@ -2,6 +2,7 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaClass("java.nio.charset.Charset")
 open class Charset: JavaObject {
   @JavaMethod
@@ -47,3 +48,4 @@ extension JavaClass<Charset> {
   @JavaStaticMethod
   public func isSupported(_ arg0: String) -> Bool
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/Closeable.swift

@@ -2,8 +2,10 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaInterface("java.io.Closeable")
 public struct Closeable {
   @JavaMethod
   public func close() throws
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/File.swift

@@ -2,6 +2,7 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaClass("java.io.File")
 open class File: JavaObject {
   @JavaMethod
@@ -164,3 +165,4 @@ extension JavaClass<File> {
   @JavaStaticMethod
   public func createTempFile(_ arg0: String, _ arg1: String, _ arg2: File?) throws -> File!
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/FileDescriptor.swift

@@ -2,6 +2,7 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaClass("java.io.FileDescriptor")
 open class FileDescriptor: JavaObject {
   @JavaMethod
@@ -23,3 +24,4 @@ extension JavaClass<FileDescriptor> {
   @JavaStaticField(isFinal: true)
   public var err: FileDescriptor!
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/FileReader.swift

@@ -2,6 +2,7 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaClass("java.io.FileReader")
 open class FileReader: InputStreamReader {
   @JavaMethod
@@ -19,3 +20,4 @@ open class FileReader: InputStreamReader {
   @JavaMethod
   @_nonoverride public convenience init(_ arg0: String, environment: JNIEnvironment? = nil) throws
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/Flushable.swift

@@ -2,8 +2,10 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaInterface("java.io.Flushable")
 public struct Flushable {
   @JavaMethod
   public func flush() throws
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/InputStream.swift

@@ -2,6 +2,7 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaClass("java.io.InputStream", implements: Closeable.self)
 open class InputStream: JavaObject {
   @JavaMethod
@@ -53,3 +54,4 @@ extension JavaClass<InputStream> {
   @JavaStaticMethod
   public func nullInputStream() -> InputStream!
 }
+#endif

Sources/JavaStdlib/JavaIO/generated/InputStreamReader.swift

@@ -2,6 +2,7 @@
 import SwiftJava
 import CSwiftJavaJNI
 
+#if SwiftJavaMacrosSupport
 @JavaClass("java.io.InputStreamReader")
 open class InputStreamReader: Reader {
   @JavaMethod
@@ -28,3 +29,4 @@ open class InputStreamReader: Reader {
   @JavaMethod
   open func getEncoding() -> String
 }
+#endif