Fix #3549: Load .tasty from jar if necessary

compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala

@@ -8,12 +8,13 @@ import SymDenotations._, unpickleScala2.Scala2Unpickler._, Constants._, Annotati
 import NameKinds.{ModuleClassName, DefaultGetterName}
 import ast.tpd._
 import java.io.{ ByteArrayInputStream, DataInputStream, File, IOException }
+import java.nio
 import java.lang.Integer.toHexString
 import scala.collection.{ mutable, immutable }
 import scala.collection.mutable.{ ListBuffer, ArrayBuffer }
 import scala.annotation.switch
 import typer.Checking.checkNonCyclic
-import io.{AbstractFile, PlainFile}
+import io.{AbstractFile, PlainFile, Path, ZipArchive, JarArchive}
 import scala.util.control.NonFatal
 
 object ClassfileParser {
@@ -781,11 +782,28 @@ class ClassfileParser(
 
       if (scan(tpnme.TASTYATTR)) {
         val attrLen = in.nextInt
-        if (attrLen == 0) {
-          // A tasty attribute implies the existence of the .tasty file
-          val file = new PlainFile(io.File(classfile.jpath).changeExtension("tasty"))
-          if (file.exists) return unpickleTASTY(new AbstractFileReader(file).nextBytes(file.sizeOption.get))
-          else ctx.error("Could not find " + file)
+        if (attrLen == 0) { // A tasty attribute implies the existence of the .tasty file
+          def readTastyForClass(jpath: nio.file.Path): Array[Byte] = {
+            val plainFile = new PlainFile(io.File(jpath).changeExtension("tasty"))
+            if (plainFile.exists) plainFile.toByteArray
+            else {
+              ctx.error("Could not find " + plainFile)
+              Array.empty
+            }
+          }
+          val tastyBytes = classfile.underlyingSource match { // TODO: simplify when #3552 is fixed
+            case None =>
+              ctx.error("Could not load TASTY from .tasty for virtual file " + classfile)
+              Array.empty[Byte]
+            case Some(jar: ZipArchive) => // We are in a jar
+              val jarFile = JarArchive.open(io.File(jar.jpath))
+              try readTastyForClass(jarFile.jpath.resolve(classfile.path))
+              finally jarFile.close()
+            case _ =>
+              readTastyForClass(classfile.jpath)
+          }
+          if (tastyBytes.nonEmpty)
+            return unpickleTASTY(tastyBytes)
         }
         else return unpickleTASTY(in.nextBytes(attrLen))
       }

compiler/src/dotty/tools/io/JarArchive.scala

@@ -16,12 +16,17 @@ object JarArchive {
   /** Create a new jar file. Overwrite if file already exists */
   def create(path: Path): JarArchive = {
     require(path.extension == "jar")
-
     path.delete()
+    open(path, create = true)
+  }
+
+  /** Create a jar file. */
+  def open(path: Path, create: Boolean = false): JarArchive = {
+    require(path.extension == "jar")
 
     // creating a new zip file system by using the JAR URL syntax:
     // https://docs.oracle.com/javase/7/docs/technotes/guides/io/fsp/zipfilesystemprovider.html
-    val env = Map("create" -> "true").asJava
+    val env = Map("create" -> create.toString).asJava
     val uri = java.net.URI.create("jar:file:" + path.toAbsolute.path)
     val fs = FileSystems.newFileSystem(uri, env)
 

project/scripts/sbtTests

@@ -30,7 +30,7 @@ fi
 
 # check that `sbt dotc -decompile` runs
 echo "testing sbt dotc -decompile"
-./project/scripts/sbt ";dotc -decompile -code -color:never -classpath out/scriptedtest1 dotrtest.Test" >  sbtdotc3.out
+./project/scripts/sbt ";dotc -decompile -color:never -classpath out/scriptedtest1 dotrtest.Test" >  sbtdotc3.out
 cat sbtdotc3.out
 if grep -e "def main(args: Array\[String\]): Unit =" sbtdotc3.out; then
     echo "output ok"
@@ -39,11 +39,20 @@ else
     exit -1
 fi
 echo "testing sbt dotr with no -classpath"
-
 ./project/scripts/sbt ";dotc tests/pos/sbtDotrTest.scala; dotr dotrtest.Test" > sbtdotr3.out
 cat sbtdotr3.out
 if grep -e "dotr test ok" sbtdotr3.out; then
     echo "output ok"
 else
     exit -1
 fi
+
+echo "testing loading tasty from .tasty file in jar"
+./project/scripts/sbt ";dotc -d out/scriptedtest4.jar -YemitTasty tests/pos/sbtDotrTest.scala; dotc -decompile -classpath out/scriptedtest4.jar -color:never dotrtest.Test" > sbtdot4.out
+cat sbtdot4.out
+if grep -e "def main(args: Array\[String\]): Unit =" sbtdot4.out; then
+    echo "output ok"
+else
+    echo "failed output check"
+    exit -1
+fi