Make the new bahavior configurable and compatible with the previous release so there is no implicit behavior change

Author: pomadchin

README.md

@@ -153,12 +153,18 @@ Since this plugin is basically a command-line wrapper, native build tools must f
 
 An initial, compatible build template can be obtained by running `sbt nativeInit <tool>`. Once the native build tool initialised, projects are built by calling the `sbt nativeCompile` task.
 
-Source and output directories are configurable
+Source and output directories are configurable:
 ```scala
 nativeCompile / sourceDirectory := sourceDirectory.value / "native"
 nativeCompile / target := target.value / "native" / nativePlatform.value
 ```
 
+Some JNI projects may produce more than a single output. If that's an intended behavior it's possible to include all of the produced 
+binaries into the native package:
+```scala
+nativeMultipleOutputs := true
+```
+
 #### CMake
 
 A regular `CMake` native project definition usually looks this following way:

plugin/src/main/scala/com/github/sbt/jni/build/BuildTool.scala

@@ -77,12 +77,12 @@ trait BuildTool {
   /**
    * Get an instance (build configuration) of this tool, in the specified directory.
    */
-  def getInstance(baseDirectory: File, buildDirectory: File, logger: Logger): Instance
+  def getInstance(baseDirectory: File, buildDirectory: File, logger: Logger, multipleOutputs: Boolean): Instance
 
   /**
    * At least one produced library is expected.
    */
-  def validate(list: List[File], logger: Logger): List[File] = {
+  def validate(list: List[File], multipleOutputs: Boolean, logger: Logger): List[File] = {
     list match {
       case Nil =>
         sys.error(
@@ -91,6 +91,15 @@ trait BuildTool {
         )
       case list @ _ :: Nil =>
         list
+
+      case head :: _ if !multipleOutputs =>
+        logger.warn(
+          "More than one file was created during compilation, " +
+            s"only the first one (${head.getAbsolutePath}) will be used." +
+            "Consider setting nativeMultipleOutputs := true."
+        )
+        List(head)
+
       case list =>
         logger.info("More than one file was created during compilation.")
         list

plugin/src/main/scala/com/github/sbt/jni/build/CMake.scala

@@ -14,11 +14,12 @@ class CMake(protected val configuration: Seq[String]) extends BuildTool with Con
     "/com/github/sbt/jni/templates/CMakeLists.txt" -> "CMakeLists.txt"
   )
 
-  override def getInstance(baseDir: File, buildDir: File, logger: Logger) = new Instance {
+  override def getInstance(baseDir: File, buildDir: File, logger: Logger, nativeMultipleOutputs: Boolean) = new Instance {
 
     override def log = logger
     override def baseDirectory = baseDir
     override def buildDirectory = buildDir
+    override def multipleOutputs = nativeMultipleOutputs
 
     def cmakeProcess(args: String*): ProcessBuilder = Process("cmake" +: args, buildDirectory)
 

plugin/src/main/scala/com/github/sbt/jni/build/Cargo.scala

@@ -18,10 +18,10 @@ class Cargo(protected val configuration: Seq[String]) extends BuildTool {
 
   def release: Boolean = configuration.exists(_.toLowerCase.contains("release"))
 
-  def getInstance(baseDirectory: File, buildDirectory: File, logger: sbt.Logger): Instance =
-    new Instance(baseDirectory, logger)
+  def getInstance(baseDirectory: File, buildDirectory: File, logger: sbt.Logger, multipleOutputs: Boolean): Instance =
+    new Instance(baseDirectory, logger, multipleOutputs)
 
-  class Instance(protected val baseDirectory: File, protected val logger: sbt.Logger) extends super.Instance {
+  class Instance(protected val baseDirectory: File, protected val logger: sbt.Logger, protected val multipleOutputs: Boolean) extends super.Instance {
     // IntelliJ friendly logger, IntelliJ doesn't start tests if a line is printed as "error", which Cargo does for regular output
     protected val log: ProcessLogger = new ProcessLogger {
       def out(s: => String): Unit = logger.info(s)
@@ -44,7 +44,7 @@ class Cargo(protected val configuration: Seq[String]) extends BuildTool {
       val products: List[File] =
         (targetDirectory / subdir * ("*.so" | "*.dylib")).get.filter(_.isFile).toList
 
-      validate(products, logger)
+      validate(products, multipleOutputs, logger)
     }
   }
 }

plugin/src/main/scala/com/github/sbt/jni/build/ConfigureMakeInstall.scala

@@ -13,6 +13,7 @@ trait ConfigureMakeInstall { self: BuildTool =>
   trait Instance extends self.Instance {
 
     def log: Logger
+    def multipleOutputs: Boolean
     def baseDirectory: File
     def buildDirectory: File
 
@@ -36,7 +37,7 @@ trait ConfigureMakeInstall { self: BuildTool =>
       val products: List[File] =
         (targetDirectory ** ("*.so" | "*.dylib")).get.filter(_.isFile).toList
 
-      validate(products, log)
+      validate(products, multipleOutputs, log)
     }
   }
 

plugin/src/main/scala/com/github/sbt/jni/build/Meson.scala

@@ -15,11 +15,12 @@ class Meson(protected val configuration: Seq[String]) extends BuildTool with Con
     "/com/github/sbt/jni/templates/meson.options" -> "meson.options"
   )
 
-  override def getInstance(baseDir: File, buildDir: File, logger: Logger) = new Instance {
+  override def getInstance(baseDir: File, buildDir: File, logger: Logger, nativeMultipleOutputs: Boolean) = new Instance {
 
     override def log = logger
     override def baseDirectory = baseDir
     override def buildDirectory = buildDir
+    override def multipleOutputs = nativeMultipleOutputs
 
     def mesonProcess(args: String*): ProcessBuilder = Process("meson" +: args, buildDirectory)
 

plugin/src/main/scala/com/github/sbt/jni/plugins/JniNative.scala

@@ -30,6 +30,10 @@ object JniNative extends AutoPlugin {
       "Initialize a native build script from a template."
     )
 
+    val nativeMultipleOutputs = taskKey[Boolean](
+      "Enable multiple native outputs support. Disabled by default."
+    )
+
   }
   import autoImport._
 
@@ -79,8 +83,8 @@ object JniNative extends AutoPlugin {
             tools.map(_.name).mkString(",")
         )
       )
-
     },
+    nativeMultipleOutputs := false,
     nativeBuildToolInstance := {
       val tool = nativeBuildTool.value
       val srcDir = (nativeCompile / sourceDirectory).value
@@ -89,7 +93,8 @@ object JniNative extends AutoPlugin {
       tool.getInstance(
         baseDirectory = srcDir,
         buildDirectory = buildDir,
-        logger = streams.value.log
+        logger = streams.value.log,
+        multipleOutputs = nativeMultipleOutputs.value
       )
     },
     nativeCompile / clean := {