Reorganize build: SwiftKit has "swift kit" core, and SwiftKitExample

Further progress on cleaning up the build. We're still having issues
with various runtime issues but this gets us to a more understandable
separation of "what is a sample" and "what is the library". There's more
to be done before we can kill off `make` but this does quite some
progress.

- Sample apps "anything with a main()" have their own place; it used to
  be very mixed up in the same target; together with the example lib
    - `JavaKitSampleApp` there's a sample for javakit which uses the
      `JavaKitExample` defined swift type
    - `SwiftKitSampleApp` the jextract demo app, uses the
      `ExampleSwiftLibrary`
    - those JavaKitExample and ExampleSwiftLibrary could use further
      moving out of `Sources/...` as they're example stuff, not "the
library" but I leave at this for now...

Running samples: ./gradlew Samples:SwiftKitSampleApp:run
(Samples:Name:run)

- `./gradlew test` does the jextract and whatever the sample apps need
- make is still around; didn't hook up any of the javakit generation
- generated sources no longer in wrong directory; `src/generated/`... as
  the usual convention in Java land (and not committed)

Author: ktoso

.github/workflows/pull_request.yml

@@ -41,11 +41,8 @@ jobs:
         #          distribution: 'zulu'
         #          java-version: '22'
         #          cache: 'gradle'
-      - name: Generate sources (make) (Temporary)
-        # TODO: this should be triggered by the respective builds
-        run: make jextract-run
       - name: Gradle build
-        run: ./gradlew build --no-daemon
+        run: ./gradlew build --info --no-daemon
 
   test-swift:
     name: Swift tests (swift:${{ matrix.swift_version }} jdk:${{matrix.jdk_vendor}} os:${{ matrix.os_version }})

.gitignore

@@ -9,10 +9,15 @@ DerivedData/
 .netrc
 *.class
 bin/
+BuildLogic/out/
 
 # Ignore gradle build artifacts
 .gradle
 **/build/
+lib/
+
+# Ignore package resolved
+Package.resolved
 
 # Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
 !gradle-wrapper.jar
@@ -24,4 +29,4 @@ bin/
 .gradletasknamecache
 
 # Ignore generated sources
-JavaSwiftKitDemo/src/main/java/com/example/swift/generated/*
+**/generated/

BuildLogic/src/main/kotlin/build-logic.java-common-conventions.gradle.kts

@@ -12,6 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+import java.util.*
+
 plugins {
     java
 }
@@ -40,16 +42,39 @@ tasks.withType(JavaCompile::class).forEach {
     it.options.compilerArgs.add("-Xlint:preview")
 }
 
+
+fun javaLibraryPaths(): List<String> {
+    val osName = System.getProperty("os.name")
+    val osArch = System.getProperty("os.arch")
+    val isLinux = osName.lowercase(Locale.getDefault()).contains("linux")
+
+    return listOf(
+        if (osName.lowercase(Locale.getDefault()).contains("linux")) {
+            """$rootDir/.build/$osArch-unknown-linux-gnu/debug/"""
+        } else {
+            if (osArch.equals("aarch64")) {
+                """$rootDir/.build/arm64-apple-macosx/debug/"""
+            } else {
+                """$rootDir/.build/$osArch-apple-macosx/debug/"""
+            }
+        },
+        if (isLinux) {
+            "/usr/lib/swift/linux"
+        } else {
+            // assume macOS
+            "/usr/lib/swift/"
+        }
+    )
+}
+
+
 // Configure paths for native (Swift) libraries
 tasks.test {
     jvmArgs(
         "--enable-native-access=ALL-UNNAMED",
 
         // Include the library paths where our dylibs are that we want to load and call
-        "-Djava.library.path=" + listOf(
-            """$rootDir/.build/arm64-apple-macosx/debug/""",
-            "/usr/lib/swift/"
-        ).joinToString(File.pathSeparator)
+        "-Djava.library.path=" + javaLibraryPaths().joinToString(File.pathSeparator)
     )
 }
 
@@ -60,14 +85,15 @@ tasks.withType<Test> {
 }
 
 
-val buildSwiftJExtract = tasks.register<Exec>("buildSwiftJExtract") {
-    description = "Builds Swift targets, including jextract-swift"
-
-    workingDir("..")
-    commandLine("make")
-}
-
-tasks.build {
-    dependsOn(buildSwiftJExtract)
-}
+// TODO: This is a crude workaround, we'll remove 'make' soon and properly track build dependencies
+// val buildSwiftJExtract = tasks.register<Exec>("buildMake") {
+//    description = "Triggers 'make' build"
+//
+//    workingDir(rootDir)
+//    commandLine("make")
+// }
+//
+// tasks.build {
+//     dependsOn(buildSwiftJExtract)
+// }
 

Makefile

@@ -37,17 +37,15 @@ BUILD_DIR := .build/$(ARCH_SUBDIR)-apple-macosx
 LIB_SUFFIX := dylib
 endif
 
+SAMPLES_DIR := "Samples"
 
 all: generate-all
 
-$(BUILD_DIR)/debug/libJavaKit.$(LIB_SUFFIX) $(BUILD_DIR)/debug/libJavaKitExample.$(LIB_SUFFIX) $(BUILD_DIR)/debug/Java2Swift:
+$(BUILD_DIR)/debug/libJavaKit.$(LIB_SUFFIX) $(BUILD_DIR)/debug/Java2Swift:
 	swift build
 
-./JavaSwiftKitDemo/build/classes/java/main/com/example/swift/HelloSubclass.class: JavaSwiftKitDemo/src/main/java/com/example/swift
-	./gradlew build
-
-run: $(BUILD_DIR)/debug/libJavaKit.$(LIB_SUFFIX) $(BUILD_DIR)/debug/libJavaKitExample.$(LIB_SUFFIX) JavaSwiftKitDemo/src/main/java/com/example/swift
-	java -cp JavaSwiftKitDemo/build/classes/java/main -Djava.library.path=$(BUILD_DIR)/debug/ com.example.swift.HelloSwift
+run: $(BUILD_DIR)/debug/libJavaKit.$(LIB_SUFFIX) $(BUILD_DIR)/debug/libExampleSwiftLibrary.$(LIB_SUFFIX)
+	./gradlew Samples:JavaKitSampleApp:run
 
 Java2Swift: $(BUILD_DIR)/debug/Java2Swift
 
@@ -70,7 +68,8 @@ generate-JavaKitNetwork: Java2Swift generate-JavaKit
 generate-all: generate-JavaKit generate-JavaKitReflection generate-JavaKitJar generate-JavaKitNetwork \
 			  jextract-swift
 clean:
-	rm -rf .build
+	rm -rf .build; \
+	rm -rf Samples/SwiftKitExampleApp/src/generated/java/*
 
 format:
 	swift format --recursive . -i
@@ -81,7 +80,6 @@ format:
 
 JEXTRACT_BUILD_DIR="$(BUILD_DIR)/jextract"
 
-# Parameter: Swift source file
 define make_swiftinterface
     $(eval $@_MODULE = $(1))
     $(eval $@_FILENAME = $(2))
@@ -99,17 +97,21 @@ jextract-swift: generate-JExtract-interface-files
 
 generate-JExtract-interface-files: $(BUILD_DIR)/debug/libJavaKit.$(LIB_SUFFIX)
 	echo "Generate .swiftinterface files..."
-	@$(call make_swiftinterface, "JavaKitExample", "MySwiftLibrary")
-	@$(call make_swiftinterface, "JavaKitExample", "SwiftKit")
+	@$(call make_swiftinterface, "ExampleSwiftLibrary", "MySwiftLibrary")
+	@$(call make_swiftinterface, "SwiftKitSwift", "SwiftKit")
 
 jextract-run: jextract-swift generate-JExtract-interface-files
 	swift run jextract-swift  \
 		--package-name com.example.swift.generated \
-		--swift-module JavaKitExample \
-		--output-directory JavaSwiftKitDemo/src/main/java \
-		$(BUILD_DIR)/jextract/JavaKitExample/MySwiftLibrary.swiftinterface \
-		$(BUILD_DIR)/jextract/JavaKitExample/SwiftKit.swiftinterface
+		--swift-module ExampleSwiftLibrary \
+		--output-directory ${SAMPLES_DIR}/SwiftKitSampleApp/src/generated/java \
+		$(BUILD_DIR)/jextract/ExampleSwiftLibrary/MySwiftLibrary.swiftinterface; \
+	swift run jextract-swift \
+		--package-name org.swift.swiftkit.generated \
+		--swift-module SwiftKitSwift \
+		--output-directory ${SAMPLES_DIR}/SwiftKitSampleApp/src/generated/java \
+		$(BUILD_DIR)/jextract/SwiftKitSwift/SwiftKit.swiftinterface
 
 
 jextract-run-java: jextract-swift generate-JExtract-interface-files
-	./gradlew run
+	./gradlew Samples:SwiftKitSampleApp:run

Package.resolved

@@ -18,7 +18,7 @@ func findJavaHome() -> String {
   // This is a workaround for envs (some IDEs) which have trouble with
   // picking up env variables during the build process
   let path = "\(FileManager.default.homeDirectoryForCurrentUser.path()).java_home"
-  if let home = try? String(contentsOfFile: path) {
+  if let home = try? String(contentsOfFile: path, encoding: .utf8) {
     if let lastChar = home.last, lastChar.isNewline {
       return String(home.dropLast())
     }
@@ -36,8 +36,8 @@ let javaIncludePath = "\(javaHome)/include"
 #elseif os(macOS)
   let javaPlatformIncludePath = "\(javaIncludePath)/darwin"
 #else
+  // TODO: Handle windows as well
   #error("Currently only macOS and Linux platforms are supported, this may change in the future.")
-// TODO: Handle windows as well
 #endif
 
 let package = Package(
@@ -50,6 +50,7 @@ let package = Package(
     .macCatalyst(.v13),
   ],
   products: [
+    // ==== JavaKit (i.e. calling Java directly Swift utilities)
     .library(
       name: "JavaKit",
       targets: ["JavaKit"]
@@ -70,12 +71,6 @@ let package = Package(
       targets: ["JavaKitReflection"]
     ),
 
-    .library(
-      name: "JavaKitExample",
-      type: .dynamic,
-      targets: ["JavaKitExample"]
-    ),
-
     .library(
       name: "JavaKitVM",
       targets: ["JavaKitVM"]
@@ -86,20 +81,43 @@ let package = Package(
       targets: ["JavaTypes"]
     ),
 
-    .library(
-      name: "JExtractSwift",
-      targets: ["JExtractSwift"]
-    ),
-
     .executable(
       name: "Java2Swift",
       targets: ["Java2Swift"]
     ),
 
+    // ==== jextract-swift (extract Java accessors from Swift interface files)
+
     .executable(
       name: "jextract-swift",
       targets: ["JExtractSwiftTool"]
     ),
+
+    // Support library written in Swift for SwiftKit "Java"
+    .library(
+      name: "SwiftKitSwift",
+      type: .dynamic,
+      targets: ["SwiftKitSwift"]
+    ),
+
+    .library(
+      name: "JExtractSwift",
+      targets: ["JExtractSwift"]
+    ),
+
+    // ==== Examples
+
+    .library(
+      name: "JavaKitExample",
+      type: .dynamic,
+      targets: ["JavaKitExample"]
+    ),
+    .library(
+      name: "ExampleSwiftLibrary",
+      type: .dynamic,
+      targets: ["ExampleSwiftLibrary"]
+    ),
+
   ],
   dependencies: [
     .package(url: "https://github.com/swiftlang/swift-syntax.git", branch: "main"),
@@ -187,6 +205,22 @@ let package = Package(
         .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
       ]
     ),
+    .target(
+      name: "ExampleSwiftLibrary",
+      dependencies: [],
+      swiftSettings: [
+        .swiftLanguageMode(.v5),
+        .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
+      ]
+    ),
+    .target(
+      name: "SwiftKitSwift",
+      dependencies: [],
+      swiftSettings: [
+        .swiftLanguageMode(.v5),
+        .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
+      ]
+    ),
 
     .target(
       name: "JavaRuntime",

Package.swift

@@ -12,6 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+import org.swift.swiftkit.gradle.BuildUtils
+
 plugins {
     id("build-logic.java-application-conventions")
 }
@@ -30,6 +32,8 @@ java {
 }
 
 dependencies {
+    implementation(project(':SwiftKit'))
+
     testImplementation(platform("org.junit:junit-bom:5.10.0"))
     testImplementation("org.junit.jupiter:junit-jupiter")
 }
@@ -39,25 +43,18 @@ tasks.test {
 }
 
 application {
-    mainClass = "org.example.HelloJava2Swift"
+    mainClass = "com.example.swift.JavaKitSampleMain"
 
     // In order to silence:
     //   WARNING: A restricted method in java.lang.foreign.SymbolLookup has been called
     //   WARNING: java.lang.foreign.SymbolLookup::libraryLookup has been called by org.example.swift.JavaKitExample in an unnamed module
     //   WARNING: Use --enable-native-access=ALL-UNNAMED to avoid a warning for callers in this module
     //   WARNING: Restricted methods will be blocked in a future release unless native access is enabled
     // FIXME: Find out the proper solution to this
-    applicationDefaultJvmArgs = listOf(
-        "--enable-native-access=ALL-UNNAMED",
-
-        // Include the library paths where our dylibs are that we want to load and call
-        "-Djava.library.path=" + listOf(
-            """$rootDir/.build/arm64-apple-macosx/debug/""",
-            "/usr/lib/swift/"
-        ).joinToString(":"),
-
-        // Enable tracing downcalls (to Swift)
-        "-Djextract.trace.downcalls=true"
-    )
-}
+    applicationDefaultJvmArgs = [
+            "--enable-native-access=ALL-UNNAMED",
 
+            // Include the library paths where our dylibs are that we want to load and call
+            "-Djava.library.path=" + BuildUtils.javaLibraryPaths(rootDir).join(":")
+    ]
+}

JavaSwiftKitDemo/build.gradle.kts renamed to Samples/JavaKitSampleApp/build.gradle

@@ -14,8 +14,6 @@
 
 package com.example.swift;
 
-import com.example.swift.HelloSwift;
-
 public class HelloSubclass extends HelloSwift {
     private String greeting;