Use the Java API as a workaround

Author: ggrossetie

twirllib/src/mill/twirllib/TwirlWorker.scala

@@ -3,6 +3,7 @@ package twirllib
 
 import java.io.File
 import java.net.URLClassLoader
+import java.{lang, util}
 
 import ammonite.ops.{Path, ls}
 import mill.eval.PathRef
@@ -14,43 +15,41 @@ import scala.reflect.runtime.universe._
 class TwirlWorker {
 
   private var twirlInstanceCache = Option.empty[(Long, TwirlWorkerApi)]
+  import scala.collection.JavaConverters._
 
   private def twirl(twirlClasspath: Agg[Path]) = {
     val classloaderSig = twirlClasspath.map(p => p.toString().hashCode + p.mtime.toMillis).sum
     twirlInstanceCache match {
       case Some((sig, instance)) if sig == classloaderSig => instance
       case _ =>
+        val cl = new URLClassLoader(twirlClasspath.map(_.toIO.toURI.toURL).toArray)
+        val twirlCompilerClass = cl.loadClass("play.japi.twirl.compiler.TwirlCompiler")
+        // Use the Java API (available in Twirl 1.3+)
+        // Using reflection on a method with "Seq[String] = Nil" parameter type does not seem to work.
+
+        // REMIND: Unable to call the compile method with a primitive boolean
+        // codec and inclusiveDot will not be available
+        val compileMethod = twirlCompilerClass.getMethod("compile",
+          classOf[java.io.File],
+          classOf[java.io.File],
+          classOf[java.io.File],
+          classOf[java.lang.String],
+          classOf[util.Collection[java.lang.String]],
+          classOf[util.List[java.lang.String]])
+
         val instance = new TwirlWorkerApi {
           override def compileTwirl(source: File,
                                     sourceDirectory: File,
                                     generatedDirectory: File,
                                     formatterType: String,
                                     additionalImports: Seq[String] = Nil,
-                                    constructorAnnotations: Seq[String] = Nil,
-                                    codec: Codec = Codec(scala.util.Properties.sourceEncoding),
-                                    inclusiveDot: Boolean = false) {
-            val cl = new URLClassLoader(twirlClasspath.map(_.toIO.toURI.toURL).toArray)
-            val runtime = runtimeMirror(cl)
-            val moduleMirror = runtime.reflectModule(runtime.staticModule("play.twirl.compiler.TwirlCompiler"))
-            val moduleInstance = moduleMirror.instance
-            val instanceMirror = runtime.reflect(moduleInstance)
-            val compileSymbol = instanceMirror.symbol.typeSignature.member(TermName("compile")).asMethod
-            // FIXME: type erasure, unable to call "play.twirl.compiler.TwirlCompiler.compile" function
-            // https://github.com/playframework/twirl/blob/dd56444cf9ea2f95ef3961d3af911561f846df50/compiler/src/main/scala/play/twirl/compiler/TwirlCompiler.scala#L167
-
-            // scala.MatchError: List() (of class scala.collection.immutable.Nil$)
-            // at scala.reflect.runtime.JavaMirrors$JavaMirror$DerivedValueClassMetadata.unboxer$lzycompute(JavaMirrors.scala:270)
-            // at scala.reflect.runtime.JavaMirrors$JavaMirror$DerivedValueClassMetadata.unboxer(JavaMirrors.scala:269)
-            // at scala.reflect.runtime.JavaMirrors$JavaMirror$MethodMetadata.paramUnboxers(JavaMirrors.scala:416)
-            // at scala.reflect.runtime.JavaMirrors$JavaMirror$JavaTransformingMethodMirror.apply(JavaMirrors.scala:435)
-            instanceMirror.reflectMethod(compileSymbol)(source,
+                                    constructorAnnotations: Seq[String] = Nil) {
+            val o = compileMethod.invoke(null, source,
               sourceDirectory,
               generatedDirectory,
               formatterType,
-              additionalImports,
-              constructorAnnotations,
-              codec,
-              inclusiveDot)
+              additionalImports.asJava,
+              constructorAnnotations.asJava)
           }
         }
         twirlInstanceCache = Some((classloaderSig, instance))
@@ -95,9 +94,7 @@ trait TwirlWorkerApi {
                    generatedDirectory: File,
                    formatterType: String,
                    additionalImports: Seq[String] = Nil,
-                   constructorAnnotations: Seq[String] = Nil,
-                   codec: Codec = Codec(scala.util.Properties.sourceEncoding),
-                   inclusiveDot: Boolean = false)
+                   constructorAnnotations: Seq[String] = Nil)
 }
 
 object TwirlWorkerApi {

twirllib/test/src/mill/twirllib/HelloWorldTests.scala

@@ -22,7 +22,7 @@ object HelloWorldTests extends TestSuite {
 
   object HelloWorld extends HelloBase {
     object core extends HelloWorldModule {
-      override def twirlVersion = "1.2.1"
+      override def twirlVersion = "1.3.15"
     }
   }
 
@@ -50,7 +50,7 @@ object HelloWorldTests extends TestSuite {
         val Right((result, evalCount)) = eval.apply(HelloWorld.core.twirlVersion)
 
         assert(
-          result == "1.2.1",
+          result == "1.3.15",
           evalCount > 0
         )
       }