Create dotc decompiler

* `dotc -decompile <options|classes>*`

compiler/src/dotty/tools/dotc/CompilationUnit.scala

@@ -28,7 +28,7 @@ object CompilationUnit {
   /** Make a compilation unit for top class `clsd` with the contends of the `unpickled` */
   def mkCompilationUnit(clsd: ClassDenotation, unpickled: Tree, forceTrees: Boolean)(implicit ctx: Context): CompilationUnit = {
     assert(!unpickled.isEmpty, unpickled)
-    val unit1 = new CompilationUnit(new SourceFile(clsd.symbol.sourceFile, Seq()))
+    val unit1 = new CompilationUnit(new SourceFile(clsd.symbol.associatedFile, Seq()))
     unit1.tpdTree = unpickled
     if (forceTrees)
       force.traverse(unit1.tpdTree)

compiler/src/dotty/tools/dotc/decompiler/DecompilationPrinter.scala

@@ -0,0 +1,31 @@
+package dotty.tools.dotc
+package decompiler
+
+import dotty.tools.dotc.core.Contexts._
+import dotty.tools.dotc.core.Phases.Phase
+
+/** Phase that prints the trees in all loaded compilation units.
+ *
+ *  @author Nicolas Stucki
+ */
+class DecompilationPrinter extends Phase {
+
+  override def phaseName: String = "decompilationPrinter"
+
+  override def run(implicit ctx: Context): Unit = {
+    val unit = ctx.compilationUnit
+
+    val pageWidth = ctx.settings.pageWidth.value
+
+    val doubleLine = "=" * pageWidth
+    val line = "-" * pageWidth
+
+    println(doubleLine)
+    println(unit.source)
+    println(line)
+
+    val code = unit.tpdTree.show
+    println(if (ctx.useColors) printing.SyntaxHighlighting(code) else code)
+    println(line)
+  }
+}

compiler/src/dotty/tools/dotc/decompiler/Main.scala

@@ -0,0 +1,21 @@
+package dotty.tools.dotc.decompiler
+
+import dotty.tools.dotc
+import dotty.tools.dotc.core.Contexts._
+
+/** Main class of the `dotc -decompiler` decompiler.
+ *
+ * @author Nicolas Stucki
+ */
+object Main extends dotc.Driver {
+  override protected def newCompiler(implicit ctx: Context): dotc.Compiler = {
+    assert(ctx.settings.fromTasty.value)
+    new TASTYDecompiler
+  }
+
+  override def setup(args0: Array[String], rootCtx: Context): (List[String], Context) = {
+    var args = args0.filter(a => a != "-decompile")
+    args = if (args.contains("-from-tasty")) args else "-from-tasty" +: args
+    super.setup(args, rootCtx)
+  }
+}

compiler/src/dotty/tools/dotc/decompiler/TASTYDecompiler.scala

@@ -0,0 +1,16 @@
+package dotty.tools.dotc.decompiler
+
+import dotty.tools.dotc.fromtasty._
+import dotty.tools.dotc.core.Phases.Phase
+
+/** Compiler from tasty to user readable high text representation
+ *  of the compiled scala code.
+ *
+ * @author Nicolas Stucki
+ */
+class TASTYDecompiler extends TASTYCompiler {
+  override def phases: List[List[Phase]] = List(
+    List(new ReadTastyTreesFromClasses), // Load classes from tasty
+    List(new DecompilationPrinter)       // Print all loaded classes
+  )
+}

dist/bin/dotc

@@ -31,6 +31,7 @@ default_java_opts="-Xmx768m -Xms768m"
 bootcp=true
 
 CompilerMain=dotty.tools.dotc.Main
+DecompilerMain=dotty.tools.dotc.decompiler.Main
 ReplMain=dotty.tools.repl.Main
 
 PROG_NAME=$CompilerMain
@@ -82,6 +83,7 @@ case "$1" in
     -Oshort) addJava "-XX:+TieredCompilation -XX:TieredStopAtLevel=1" && shift ;;
         -repl) PROG_NAME="$ReplMain" && shift ;;
      -compile) PROG_NAME="$CompilerMain" && shift ;;
+   -decompile) PROG_NAME="$DecompilerMain" && shift ;;
          -run) PROG_NAME="$ReplMain" && shift ;;
       -bootcp) bootcp=true && shift ;;
    -nobootcp) unset bootcp && shift ;;

project/Build.scala

@@ -87,6 +87,7 @@ object Build {
   lazy val dotr =
     inputKey[Unit]("run compiled binary using the correct classpath, or the user supplied classpath")
 
+
   // Compiles the documentation and static site
   lazy val genDocs = taskKey[Unit]("run dottydoc to generate static documentation site")
 
@@ -523,8 +524,8 @@ object Build {
         }
       },
       run := dotc.evaluated,
-      dotc := runCompilerMain(false).evaluated,
-      repl := runCompilerMain(true).evaluated,
+      dotc := runCompilerMain().evaluated,
+      repl := runCompilerMain(repl = true).evaluated,
 
       // enable verbose exception messages for JUnit
       testOptions in Test += Tests.Argument(
@@ -618,16 +619,22 @@ object Build {
       }
   )
 
-  def runCompilerMain(repl: Boolean) = Def.inputTaskDyn {
+  def runCompilerMain(repl: Boolean = false) = Def.inputTaskDyn {
     val dottyLib = packageAll.value("dotty-library")
     val args0: List[String] = spaceDelimited("<arg>").parsed.toList
-    val args = args0.filter(arg => arg != "-repl")
+    val decompile = args0.contains("-decompile")
+    val args = args0.filter(arg => arg != "-repl" || arg != "-decompile")
 
     val main =
       if (repl) "dotty.tools.repl.Main"
+      else if (decompile) "dotty.tools.dotc.decompiler.Main"
       else "dotty.tools.dotc.Main"
 
-    val fullArgs = main :: insertClasspathInArgs(args, dottyLib)
+    val extraClasspath =
+      if (decompile && !args.contains("-classpath")) dottyLib + ":."
+      else dottyLib
+
+    val fullArgs = main :: insertClasspathInArgs(args, extraClasspath)
 
     (runMain in Compile).toTask(fullArgs.mkString(" ", " ", ""))
   }

project/scripts/sbtBootstrappedTests

@@ -8,7 +8,7 @@
 ./project/scripts/sbt dist-bootstrapped/pack
 
 # check that `dotc` compiles and `dotr` runs it
-echo "testing sbt dotc and dotr"
+echo "testing ./bin/dotc and ./bin/dotr"
 mkdir out/scriptedtest0
 ./bin/dotc tests/pos/sbtDotrTest.scala -d out/scriptedtest0
 # FIXME #3477
@@ -21,7 +21,7 @@ mkdir out/scriptedtest0
 
 
 # check that `dotc` compiles and `dotr` runs it
-echo "testing sbt dotc -from-tasty and dotr -classpath"
+echo "testing ./bin/dotc -from-tasty and dotr -classpath"
 mkdir out/scriptedtest1
 mkdir out/scriptedtest2
 ./bin/dotc tests/pos/sbtDotrTest.scala -d out/scriptedtest1/

project/scripts/sbtTests

@@ -11,6 +11,7 @@ cat sbtdotr1.out
 if grep -e "dotr test ok" sbtdotr1.out; then
     echo "output ok"
 else
+    echo "failed output check"
     exit -1
 fi
 
@@ -23,13 +24,25 @@ cat sbtdotr2.out
 if grep -e "dotr test ok" sbtdotr2.out; then
     echo "output ok"
 else
+    echo "failed output check"
+    exit -1
+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
+cat sbtdotc3.out
+if grep -e "def main(args: Array\[String\]): Unit =" sbtdotc3.out; then
+    echo "output ok"
+else
+    echo "failed output check"
     exit -1
 fi
 echo "testing sbt dotr with no -classpath"
 
-./project/scripts/sbt ";dotc tests/pos/sbtDotrTest.scala; dotr dotrtest.Test" > sbtdotp1.out
-cat sbtdotp1.out
-if grep -e "dotr test ok" sbtdotp1.out; then
+./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