From f77ac08102c6a36e2476745b1a8f42ccf0097cbd Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Fri, 6 Apr 2018 10:03:46 +0200
Subject: [PATCH 1/9] Test compilation of decompiled code

---
 .../decompiler/DecompilationPrinter.scala     | 14 ++++-------
 .../dotty/tools/dotc/decompiler/Main.scala    |  5 ++--
 .../dotc/printing/DecompilerPrinter.scala     |  6 ++++-
 .../tools/dotc/printing/RefinedPrinter.scala  |  3 ++-
 .../dotty/tools/dotc/FromTastyTests.scala     | 24 ++++++++++++-------
 .../dotty/tools/vulpix/ParallelTesting.scala  | 24 ++++++++++++-------
 tests/pos/lambda.decompiled                   |  7 ++----
 tests/pos/methodTypes.decompiled              |  7 ++----
 tests/pos/simpleCaseObject.decompiled         |  9 +++----
 tests/pos/simpleClass-2.decompiled            | 12 +++-------
 tests/pos/simpleClass.decompiled              | 12 +++-------
 tests/pos/simpleDoWhile.decompiled            |  7 ++----
 tests/pos/simpleWhile.decompiled              |  7 ++----
 tests/run/puzzle.decompiled                   |  9 +++----
 14 files changed, 65 insertions(+), 81 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/decompiler/DecompilationPrinter.scala b/compiler/src/dotty/tools/dotc/decompiler/DecompilationPrinter.scala
index 51533640a3bb..d3a855bd8949 100644
--- a/compiler/src/dotty/tools/dotc/decompiler/DecompilationPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/decompiler/DecompilationPrinter.scala
@@ -24,7 +24,7 @@ class DecompilationPrinter extends Phase {
       var os: OutputStream = null
       var ps: PrintStream = null
       try {
-        os = File(outputDir + ".decompiled").outputStream(append = true)
+        os = File(outputDir + "/decompiled.scala").outputStream(append = true)
         ps = new PrintStream(os)
         printToOutput(ps)
       } finally {
@@ -38,21 +38,15 @@ class DecompilationPrinter extends Phase {
     val unit = ctx.compilationUnit
     val pageWidth = ctx.settings.pageWidth.value
     val printLines = ctx.settings.printLines.value
-    val doubleLine = "=" * pageWidth
-    val line = "-" * pageWidth
-
-    out.println(doubleLine)
-    out.println(unit.source)
-    out.println(line)
 
+    out.println(s"/** Decompiled from $unit */")
     val printer = new DecompilerPrinter(ctx)
-
     out.println(printer.toText(unit.tpdTree).mkString(pageWidth, printLines))
-    out.println(line)
 
     if (ctx.settings.printTasty.value) {
+      out.println("/*")
       new TastyPrinter(unit.pickled.head._2).printContents()
-      out.println(line)
+      out.println("*/")
     }
   }
 }
diff --git a/compiler/src/dotty/tools/dotc/decompiler/Main.scala b/compiler/src/dotty/tools/dotc/decompiler/Main.scala
index c91afc45fb34..3d4ebb214c14 100644
--- a/compiler/src/dotty/tools/dotc/decompiler/Main.scala
+++ b/compiler/src/dotty/tools/dotc/decompiler/Main.scala
@@ -14,13 +14,14 @@ object Main extends dotc.Driver {
     assert(ctx.settings.fromTasty.value)
     val outputDir = ctx.settings.outputDir.value
     if (outputDir != ".")
-      Files.deleteIfExists(Paths.get(outputDir + ".decompiled"))
+      Files.deleteIfExists(Paths.get(outputDir + "/decompiled.scala"))
     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
+    if (!args.contains("-from-tasty")) args = "-from-tasty" +: args
+    if (args.contains("-d")) args = "-color:never" +: args
     super.setup(args, rootCtx)
   }
 }
diff --git a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
index 288d07c30ff3..e33e9468341a 100644
--- a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
@@ -55,7 +55,11 @@ class DecompilerPrinter(_ctx: Context) extends RefinedPrinter(_ctx) {
   }
 
   override protected def toTextTemplate(impl: Template, ofNew: Boolean = false): Text = {
-    val impl1 = impl.copy(parents = impl.parents.filterNot(_.symbol.maybeOwner == defn.ObjectClass))
+    def filter(sym: Symbol): Boolean = {
+      sym.maybeOwner == defn.ObjectClass ||
+      (sym == defn.ProductClass && impl.symbol.owner.is(Case))
+    }
+    val impl1 = impl.copy(parents = impl.parents.filterNot(p => filter(p.symbol)))
     super.toTextTemplate(impl1, ofNew)
   }
 
diff --git a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index 6500693da068..7d8da3d0a2cc 100644
--- a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -640,7 +640,8 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     val tparamsTxt = withEnclosingDef(constr) { tparamsText(tparams) }
     val primaryConstrs = if (constr.rhs.isEmpty) Nil else constr :: Nil
     val prefix: Text =
-      if (vparamss.isEmpty || primaryConstrs.nonEmpty) tparamsTxt
+      if (constr.symbol.owner.is(Module)) " "
+      else if (vparamss.isEmpty || primaryConstrs.nonEmpty) tparamsTxt
       else {
         var modsText = modText(constr.mods, "")
         if (!modsText.isEmpty) modsText = " " ~ modsText
diff --git a/compiler/test/dotty/tools/dotc/FromTastyTests.scala b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
index 750245d464a2..b89d58ef7332 100644
--- a/compiler/test/dotty/tools/dotc/FromTastyTests.scala
+++ b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
@@ -26,7 +26,7 @@ class FromTastyTests extends ParallelTesting {
     // > dotc -Ythrough-tasty -Ycheck:all <source>
 
     implicit val testGroup: TestGroup = TestGroup("posTestFromTasty")
-    val (step1, step2, step3) = compileTastyInDir("tests/pos", defaultOptions,
+    val (step1, step2, step3, step4) = compileTastyInDir("tests/pos", defaultOptions,
       blacklist = Set(
         // Wrong number of arguments (only on bootstrapped)
         "i3130b.scala",
@@ -36,12 +36,16 @@ class FromTastyTests extends ParallelTesting {
 
         // MatchError in SymDenotation.sourceModule on a ThisType
         "t3612.scala",
+      ),
+      recompileBlacklist = Set(
+        "simpleCaseObject"
       )
     )
     step1.checkCompile() // Compile all files to generate the class files with tasty
     step2.checkCompile() // Compile from tasty
     step3.checkCompile() // Decompile from tasty
-    (step1 + step2 + step3).delete()
+    step4.checkCompile() // Recompile decompiled code
+    (step1 + step2 + step3 + step4).delete()
   }
 
   @Test def runTestFromTasty: Unit = {
@@ -51,16 +55,20 @@ class FromTastyTests extends ParallelTesting {
     // > dotr Test
 
     implicit val testGroup: TestGroup = TestGroup("runTestFromTasty")
-    val (step1, step2, step3) = compileTastyInDir("tests/run", defaultOptions,
-       blacklist = Set(
-         // Closure type miss match
-         "eff-dependent.scala",
-       )
+    val (step1, step2, step3, step4) = compileTastyInDir("tests/run", defaultOptions,
+      blacklist = Set(
+        // Closure type miss match
+        "eff-dependent.scala",
+      ),
+      recompileBlacklist = Set(
+        "puzzle"
+      )
     )
     step1.checkCompile() // Compile all files to generate the class files with tasty
     step2.checkRuns() // Compile from tasty and run the result
     step3.checkCompile() // Decompile from tasty
-    (step1 + step2 + step3).delete()
+    step4.checkCompile() // Recompile decompiled code
+    (step1 + step2 + step3 + step4).delete()
   }
 
   private implicit class tastyCompilationTuples(tup: (CompilationTest, CompilationTest)) {
diff --git a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
index 27a40306ecd5..5ce232b95f41 100644
--- a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
+++ b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
@@ -425,16 +425,17 @@ trait ParallelTesting extends RunnerOrchestration { self =>
       reporter
     }
 
-    protected def decompile(flags0: TestFlags, suppressErrors: Boolean, targetDir: JFile): TestReporter = {
-      val decompilationOutput = new JFile(targetDir.getPath)
-      decompilationOutput.mkdir()
+    protected def decompile(flags0: TestFlags, suppressErrors: Boolean, targetDir0: JFile): TestReporter = {
+      val targetDir = new JFile(targetDir0.getParent + "_decompiled")
+      val decompilationOutput = new JFile(targetDir + "/" + targetDir0.getName)
+      decompilationOutput.mkdirs()
       val flags =
         flags0 and ("-d", decompilationOutput.getAbsolutePath) and
         "-decompile" and "-pagewidth" and "80"
 
       def hasTastyFileToClassName(f: JFile): String =
-        targetDir.toPath.relativize(f.toPath).toString.dropRight(".hasTasty".length).replace('/', '.')
-      val classes = flattenFiles(targetDir).filter(isHasTastyFile).map(hasTastyFileToClassName).sorted
+        targetDir0.toPath.relativize(f.toPath).toString.dropRight(".hasTasty".length).replace('/', '.')
+      val classes = flattenFiles(targetDir0).filter(isHasTastyFile).map(hasTastyFileToClassName).sorted
 
       val reporter =
         TestReporter.reporter(realStdout, logLevel =
@@ -522,7 +523,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
                 checkFileOpt match {
                   case Some(checkFile) =>
                     val stripTrailingWhitespaces = "(.*\\S|)\\s+".r
-                    val output = Source.fromFile(outDir + ".decompiled").getLines().map {line =>
+                    val output = Source.fromFile(outDir.getParent + "_decompiled/" + outDir.getName + "/decompiled.scala").getLines().map {line =>
                       stripTrailingWhitespaces.unapplySeq(line).map(_.head).getOrElse(line)
                     }.mkString("\n")
 
@@ -1257,8 +1258,8 @@ trait ParallelTesting extends RunnerOrchestration { self =>
    *  Tests in the first part of the tuple must be executed before the second.
    *  Both testsRequires explicit delete().
    */
-  def compileTastyInDir(f: String, flags0: TestFlags, blacklist: Set[String] = Set.empty)(
-      implicit testGroup: TestGroup): (CompilationTest, CompilationTest, CompilationTest) = {
+  def compileTastyInDir(f: String, flags0: TestFlags, blacklist: Set[String], recompileBlacklist: Set[String])(
+      implicit testGroup: TestGroup): (CompilationTest, CompilationTest, CompilationTest, CompilationTest) = {
     val outDir = defaultOutputDir + testGroup + "/"
     val flags = flags0 and "-Yretain-trees"
     val sourceDir = new JFile(f)
@@ -1284,10 +1285,15 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     // Create a CompilationTest and let the user decide whether to execute a pos or a neg test
     val generateClassFiles = compileFilesInDir(f, flags0, blacklist)
 
+    val decompilationDir = outDir + sourceDir.getName + "_decompiled"
+    new JFile(decompilationDir).mkdirs()
+    val recompileDecompiled = compileFilesInDir(decompilationDir, flags0, recompileBlacklist)
+
     (
       generateClassFiles.keepOutput,
       new CompilationTest(targets).keepOutput,
-      new CompilationTest(targets2).keepOutput
+      new CompilationTest(targets2).keepOutput,
+      recompileDecompiled.keepOutput
     )
   }
 
diff --git a/tests/pos/lambda.decompiled b/tests/pos/lambda.decompiled
index f610dc4481a4..d8f61efaa99a 100644
--- a/tests/pos/lambda.decompiled
+++ b/tests/pos/lambda.decompiled
@@ -1,6 +1,4 @@
-================================================================================
-out/posTestFromTasty/pos/lambda/foo/Foo.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/lambda/foo/Foo.class */
 package foo {
   class Foo() {
     {
@@ -11,5 +9,4 @@ package foo {
     }
     val a: Int => Int = (x: Int) => x.*(x)
   }
-}
---------------------------------------------------------------------------------
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/tests/pos/methodTypes.decompiled b/tests/pos/methodTypes.decompiled
index 40cc677c5c03..da19e193f895 100644
--- a/tests/pos/methodTypes.decompiled
+++ b/tests/pos/methodTypes.decompiled
@@ -1,9 +1,6 @@
-================================================================================
-out/posTestFromTasty/pos/methodTypes/Foo.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/methodTypes/Foo.class */
 class Foo() {
   val x: Int = 1
   def y: Int = 2
   def z(): Int = 3
-}
---------------------------------------------------------------------------------
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/tests/pos/simpleCaseObject.decompiled b/tests/pos/simpleCaseObject.decompiled
index abf361f74dda..58f307b86936 100644
--- a/tests/pos/simpleCaseObject.decompiled
+++ b/tests/pos/simpleCaseObject.decompiled
@@ -1,8 +1,6 @@
-================================================================================
-out/posTestFromTasty/pos/simpleCaseObject/foo/Foo.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/simpleCaseObject/foo/Foo.class */
 package foo {
-  case object Foo() extends _root_.scala.Product { this: foo.Foo.type =>
+  case object Foo  { this: foo.Foo.type =>
     override def hashCode(): Int = 1045991777
     override def toString(): String = "Foo"
     override def canEqual(that: Any): Boolean =
@@ -15,5 +13,4 @@ package foo {
           case _ => throw new IndexOutOfBoundsException(n.toString())
         }
   }
-}
---------------------------------------------------------------------------------
+}
\ No newline at end of file
diff --git a/tests/pos/simpleClass-2.decompiled b/tests/pos/simpleClass-2.decompiled
index 23e04b8e8701..b8f785f36508 100644
--- a/tests/pos/simpleClass-2.decompiled
+++ b/tests/pos/simpleClass-2.decompiled
@@ -1,14 +1,8 @@
-================================================================================
-out/posTestFromTasty/pos/simpleClass-2/foo/A.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/simpleClass-2/foo/A.class */
 package foo {
   class A() extends foo.B() {}
 }
---------------------------------------------------------------------------------
-================================================================================
-out/posTestFromTasty/pos/simpleClass-2/foo/B.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/simpleClass-2/foo/B.class */
 package foo {
   class B() {}
-}
---------------------------------------------------------------------------------
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/tests/pos/simpleClass.decompiled b/tests/pos/simpleClass.decompiled
index 814df8bceddc..794c0baff401 100644
--- a/tests/pos/simpleClass.decompiled
+++ b/tests/pos/simpleClass.decompiled
@@ -1,14 +1,8 @@
-================================================================================
-out/posTestFromTasty/pos/simpleClass/foo/A.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/simpleClass/foo/A.class */
 package foo {
   class A() {}
 }
---------------------------------------------------------------------------------
-================================================================================
-out/posTestFromTasty/pos/simpleClass/foo/B.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/simpleClass/foo/B.class */
 package foo {
   class B() extends foo.A() {}
-}
---------------------------------------------------------------------------------
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/tests/pos/simpleDoWhile.decompiled b/tests/pos/simpleDoWhile.decompiled
index 811801631451..e8f316aec6db 100644
--- a/tests/pos/simpleDoWhile.decompiled
+++ b/tests/pos/simpleDoWhile.decompiled
@@ -1,6 +1,4 @@
-================================================================================
-out/posTestFromTasty/pos/simpleDoWhile/Foo.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/simpleDoWhile/Foo.class */
 class Foo() {
   def foo: Unit =
     {
@@ -11,5 +9,4 @@ class Foo() {
         }
       while (i.!=(0))
     }
-}
---------------------------------------------------------------------------------
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/tests/pos/simpleWhile.decompiled b/tests/pos/simpleWhile.decompiled
index 8ae185525386..1fec54f3fd45 100644
--- a/tests/pos/simpleWhile.decompiled
+++ b/tests/pos/simpleWhile.decompiled
@@ -1,6 +1,4 @@
-================================================================================
-out/posTestFromTasty/pos/simpleWhile/Foo.class
---------------------------------------------------------------------------------
+/** Decompiled from out/posTestFromTasty/pos/simpleWhile/Foo.class */
 class Foo() {
   def foo: Unit =
     {
@@ -10,5 +8,4 @@ class Foo() {
           i = 0
         }
     }
-}
---------------------------------------------------------------------------------
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/tests/run/puzzle.decompiled b/tests/run/puzzle.decompiled
index 870c215b4a1d..5a3236b7c1fc 100644
--- a/tests/run/puzzle.decompiled
+++ b/tests/run/puzzle.decompiled
@@ -1,7 +1,5 @@
-================================================================================
-out/runTestFromTasty/run/puzzle/Test.class
---------------------------------------------------------------------------------
-object Test() { this: Test.type =>
+/** Decompiled from out/runTestFromTasty/run/puzzle/Test.class */
+object Test  { this: Test.type =>
   def main(args: Array[String]): Unit =
     {
       println(if false then 5.0 else 53.0)
@@ -11,5 +9,4 @@ object Test() { this: Test.type =>
       val y: Float = Long.long2float(z)
       ()
     }
-}
---------------------------------------------------------------------------------
\ No newline at end of file
+}
\ No newline at end of file

From 1160d2c221b4b73f3758c01f5291a8cda9151459 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Sun, 8 Apr 2018 14:56:05 +0200
Subject: [PATCH 2/9] Do not print self types of module objects

---
 compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala | 2 +-
 compiler/test/dotty/tools/dotc/FromTastyTests.scala         | 1 -
 tests/pos/simpleCaseObject.decompiled                       | 2 +-
 tests/run/puzzle.decompiled                                 | 2 +-
 4 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index 7d8da3d0a2cc..b3c993b2c844 100644
--- a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -652,7 +652,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     val selfText = {
       val selfName = if (self.name == nme.WILDCARD) keywordStr("this") else self.name.toString
       (selfName ~ optText(self.tpt)(": " ~ _) ~ " =>").close
-    } provided !self.isEmpty
+    } provided (!self.isEmpty && !constr.symbol.owner.is(Module))
 
     val body = if (ctx.settings.YtestPickler.value) {
       // Pickling/unpickling reorders the body members, so we need to homogenize
diff --git a/compiler/test/dotty/tools/dotc/FromTastyTests.scala b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
index b89d58ef7332..fcd368d4cb0a 100644
--- a/compiler/test/dotty/tools/dotc/FromTastyTests.scala
+++ b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
@@ -61,7 +61,6 @@ class FromTastyTests extends ParallelTesting {
         "eff-dependent.scala",
       ),
       recompileBlacklist = Set(
-        "puzzle"
       )
     )
     step1.checkCompile() // Compile all files to generate the class files with tasty
diff --git a/tests/pos/simpleCaseObject.decompiled b/tests/pos/simpleCaseObject.decompiled
index 58f307b86936..cffa8ea17e3d 100644
--- a/tests/pos/simpleCaseObject.decompiled
+++ b/tests/pos/simpleCaseObject.decompiled
@@ -1,6 +1,6 @@
 /** Decompiled from out/posTestFromTasty/pos/simpleCaseObject/foo/Foo.class */
 package foo {
-  case object Foo  { this: foo.Foo.type =>
+  case object Foo  {
     override def hashCode(): Int = 1045991777
     override def toString(): String = "Foo"
     override def canEqual(that: Any): Boolean =
diff --git a/tests/run/puzzle.decompiled b/tests/run/puzzle.decompiled
index 5a3236b7c1fc..220e4f4a0264 100644
--- a/tests/run/puzzle.decompiled
+++ b/tests/run/puzzle.decompiled
@@ -1,5 +1,5 @@
 /** Decompiled from out/runTestFromTasty/run/puzzle/Test.class */
-object Test  { this: Test.type =>
+object Test  {
   def main(args: Array[String]): Unit =
     {
       println(if false then 5.0 else 53.0)

From cd663ec800940aab01539ad06bc14edd0925853c Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Sun, 8 Apr 2018 15:06:47 +0200
Subject: [PATCH 3/9] Enable runtime tests on recompiled code

---
 compiler/test/dotty/tools/dotc/FromTastyTests.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/test/dotty/tools/dotc/FromTastyTests.scala b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
index fcd368d4cb0a..b674c1aa0ee1 100644
--- a/compiler/test/dotty/tools/dotc/FromTastyTests.scala
+++ b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
@@ -66,7 +66,7 @@ class FromTastyTests extends ParallelTesting {
     step1.checkCompile() // Compile all files to generate the class files with tasty
     step2.checkRuns() // Compile from tasty and run the result
     step3.checkCompile() // Decompile from tasty
-    step4.checkCompile() // Recompile decompiled code
+    step4.checkRuns() // Recompile decompiled code
     (step1 + step2 + step3 + step4).delete()
   }
 

From c1d1c212e4b7242ee023838cfaf0cf135c47ad90 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Mon, 9 Apr 2018 11:05:44 +0200
Subject: [PATCH 4/9] Rename filter to isSyntheticParent

---
 .../src/dotty/tools/dotc/printing/DecompilerPrinter.scala     | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
index e33e9468341a..d308014670cd 100644
--- a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
@@ -55,11 +55,11 @@ class DecompilerPrinter(_ctx: Context) extends RefinedPrinter(_ctx) {
   }
 
   override protected def toTextTemplate(impl: Template, ofNew: Boolean = false): Text = {
-    def filter(sym: Symbol): Boolean = {
+    def isSyntheticParent(sym: Symbol): Boolean = {
       sym.maybeOwner == defn.ObjectClass ||
       (sym == defn.ProductClass && impl.symbol.owner.is(Case))
     }
-    val impl1 = impl.copy(parents = impl.parents.filterNot(p => filter(p.symbol)))
+    val impl1 = impl.copy(parents = impl.parents.filterNot(p => isSyntheticParent(p.symbol)))
     super.toTextTemplate(impl1, ofNew)
   }
 

From 11fe1b9a855db83b1d1e47bbc752c6a94f89703b Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Mon, 9 Apr 2018 11:06:18 +0200
Subject: [PATCH 5/9] Override printing of self in DecompilerPrinter

---
 .../tools/dotc/printing/DecompilerPrinter.scala      |  3 +++
 .../dotty/tools/dotc/printing/RefinedPrinter.scala   | 12 +++++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
index d308014670cd..5f2cfb254804 100644
--- a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
@@ -54,6 +54,9 @@ class DecompilerPrinter(_ctx: Context) extends RefinedPrinter(_ctx) {
     decl ~~ typeText(nameIdText(tree)) ~ withEnclosingDef(tree) { toTextTemplate(impl) } ~ ""
   }
 
+  override protected def selfToText(impl: Template): Text =
+    super.selfToText(impl).provided(!impl.constr.symbol.owner.is(Module))
+
   override protected def toTextTemplate(impl: Template, ofNew: Boolean = false): Text = {
     def isSyntheticParent(sym: Symbol): Boolean = {
       sym.maybeOwner == defn.ObjectClass ||
diff --git a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index b3c993b2c844..73a077bbe803 100644
--- a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -649,11 +649,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         withEnclosingDef(constr) { addVparamssText(tparamsTxt ~~ modsText, vparamss) }
       }
     val parentsText = Text(parents map constrText, keywordStr(" with "))
-    val selfText = {
-      val selfName = if (self.name == nme.WILDCARD) keywordStr("this") else self.name.toString
-      (selfName ~ optText(self.tpt)(": " ~ _) ~ " =>").close
-    } provided (!self.isEmpty && !constr.symbol.owner.is(Module))
-
+    val selfText = selfToText(impl)
     val body = if (ctx.settings.YtestPickler.value) {
       // Pickling/unpickling reorders the body members, so we need to homogenize
       val (params, rest) = impl.body partition {
@@ -670,6 +666,12 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     prefix ~ (keywordText(" extends") provided (!ofNew && parents.nonEmpty)) ~~ parentsText ~~ bodyText
   }
 
+  protected def selfToText(impl: Template): Text = {
+    val self = impl.self
+    val selfName = if (self.name == nme.WILDCARD) keywordStr("this") else self.name.toString
+    (selfName ~ optText(self.tpt)(": " ~ _) ~ " =>").close provided (!self.isEmpty)
+  }
+
   protected def templateText(tree: TypeDef, impl: Template): Text = {
     val decl = modText(tree.mods, keywordStr(if ((tree).mods is Trait) "trait" else "class"))
     decl ~~ typeText(nameIdText(tree)) ~ withEnclosingDef(tree) { toTextTemplate(impl) } ~

From 8bfc4ec53a454a1e69d9b7c96a0d16598ea2f091 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Mon, 9 Apr 2018 11:27:15 +0200
Subject: [PATCH 6/9] Fix step4 not able to see availavble tests

They only exist after step3 has been executed
---
 .../dotty/tools/dotc/FromTastyTests.scala     | 21 ++++++++++++-------
 .../dotty/tools/vulpix/ParallelTesting.scala  |  8 +++----
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/compiler/test/dotty/tools/dotc/FromTastyTests.scala b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
index b674c1aa0ee1..432a62097f47 100644
--- a/compiler/test/dotty/tools/dotc/FromTastyTests.scala
+++ b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
@@ -26,7 +26,7 @@ class FromTastyTests extends ParallelTesting {
     // > dotc -Ythrough-tasty -Ycheck:all <source>
 
     implicit val testGroup: TestGroup = TestGroup("posTestFromTasty")
-    val (step1, step2, step3, step4) = compileTastyInDir("tests/pos", defaultOptions,
+    val (step1, step2, step3, decompilationDir) = compileTastyInDir("tests/pos", defaultOptions,
       blacklist = Set(
         // Wrong number of arguments (only on bootstrapped)
         "i3130b.scala",
@@ -36,15 +36,19 @@ class FromTastyTests extends ParallelTesting {
 
         // MatchError in SymDenotation.sourceModule on a ThisType
         "t3612.scala",
-      ),
-      recompileBlacklist = Set(
-        "simpleCaseObject"
       )
     )
     step1.checkCompile() // Compile all files to generate the class files with tasty
     step2.checkCompile() // Compile from tasty
     step3.checkCompile() // Decompile from tasty
+
+    val step4 = compileFilesInDir(decompilationDir, defaultOptions,
+      blacklist = Set(
+        "simpleCaseObject"
+      )
+    ).keepOutput
     step4.checkCompile() // Recompile decompiled code
+
     (step1 + step2 + step3 + step4).delete()
   }
 
@@ -55,18 +59,19 @@ class FromTastyTests extends ParallelTesting {
     // > dotr Test
 
     implicit val testGroup: TestGroup = TestGroup("runTestFromTasty")
-    val (step1, step2, step3, step4) = compileTastyInDir("tests/run", defaultOptions,
+    val (step1, step2, step3, decompilationDir) = compileTastyInDir("tests/run", defaultOptions,
       blacklist = Set(
         // Closure type miss match
         "eff-dependent.scala",
-      ),
-      recompileBlacklist = Set(
       )
     )
     step1.checkCompile() // Compile all files to generate the class files with tasty
     step2.checkRuns() // Compile from tasty and run the result
     step3.checkCompile() // Decompile from tasty
-    step4.checkRuns() // Recompile decompiled code
+
+    val step4 = compileFilesInDir(decompilationDir, defaultOptions, blacklist = Set()).keepOutput
+    step4.checkRuns() // Recompile and run decompiled code
+
     (step1 + step2 + step3 + step4).delete()
   }
 
diff --git a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
index 5ce232b95f41..debb4bdc5186 100644
--- a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
+++ b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
@@ -1258,8 +1258,8 @@ trait ParallelTesting extends RunnerOrchestration { self =>
    *  Tests in the first part of the tuple must be executed before the second.
    *  Both testsRequires explicit delete().
    */
-  def compileTastyInDir(f: String, flags0: TestFlags, blacklist: Set[String], recompileBlacklist: Set[String])(
-      implicit testGroup: TestGroup): (CompilationTest, CompilationTest, CompilationTest, CompilationTest) = {
+  def compileTastyInDir(f: String, flags0: TestFlags, blacklist: Set[String])(
+      implicit testGroup: TestGroup): (CompilationTest, CompilationTest, CompilationTest, String) = {
     val outDir = defaultOutputDir + testGroup + "/"
     val flags = flags0 and "-Yretain-trees"
     val sourceDir = new JFile(f)
@@ -1286,14 +1286,12 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     val generateClassFiles = compileFilesInDir(f, flags0, blacklist)
 
     val decompilationDir = outDir + sourceDir.getName + "_decompiled"
-    new JFile(decompilationDir).mkdirs()
-    val recompileDecompiled = compileFilesInDir(decompilationDir, flags0, recompileBlacklist)
 
     (
       generateClassFiles.keepOutput,
       new CompilationTest(targets).keepOutput,
       new CompilationTest(targets2).keepOutput,
-      recompileDecompiled.keepOutput
+      decompilationDir
     )
   }
 

From bcfc2b78ca00bbc4d09b7ae3a943128628ef2eb3 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Mon, 9 Apr 2018 11:40:28 +0200
Subject: [PATCH 7/9] Create TastyCompilationTest

---
 .../dotty/tools/dotc/FromTastyTests.scala     | 37 +++---------
 .../dotty/tools/vulpix/ParallelTesting.scala  | 56 +++++++++++++++----
 2 files changed, 54 insertions(+), 39 deletions(-)

diff --git a/compiler/test/dotty/tools/dotc/FromTastyTests.scala b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
index 432a62097f47..243d6f2ded00 100644
--- a/compiler/test/dotty/tools/dotc/FromTastyTests.scala
+++ b/compiler/test/dotty/tools/dotc/FromTastyTests.scala
@@ -26,7 +26,7 @@ class FromTastyTests extends ParallelTesting {
     // > dotc -Ythrough-tasty -Ycheck:all <source>
 
     implicit val testGroup: TestGroup = TestGroup("posTestFromTasty")
-    val (step1, step2, step3, decompilationDir) = compileTastyInDir("tests/pos", defaultOptions,
+    compileTastyInDir("tests/pos", defaultOptions,
       blacklist = Set(
         // Wrong number of arguments (only on bootstrapped)
         "i3130b.scala",
@@ -36,20 +36,11 @@ class FromTastyTests extends ParallelTesting {
 
         // MatchError in SymDenotation.sourceModule on a ThisType
         "t3612.scala",
-      )
-    )
-    step1.checkCompile() // Compile all files to generate the class files with tasty
-    step2.checkCompile() // Compile from tasty
-    step3.checkCompile() // Decompile from tasty
-
-    val step4 = compileFilesInDir(decompilationDir, defaultOptions,
-      blacklist = Set(
+      ),
+      recompilationBlacklist = Set(
         "simpleCaseObject"
       )
-    ).keepOutput
-    step4.checkCompile() // Recompile decompiled code
-
-    (step1 + step2 + step3 + step4).delete()
+    ).checkCompile()
   }
 
   @Test def runTestFromTasty: Unit = {
@@ -59,25 +50,13 @@ class FromTastyTests extends ParallelTesting {
     // > dotr Test
 
     implicit val testGroup: TestGroup = TestGroup("runTestFromTasty")
-    val (step1, step2, step3, decompilationDir) = compileTastyInDir("tests/run", defaultOptions,
+    compileTastyInDir("tests/run", defaultOptions,
       blacklist = Set(
         // Closure type miss match
         "eff-dependent.scala",
-      )
-    )
-    step1.checkCompile() // Compile all files to generate the class files with tasty
-    step2.checkRuns() // Compile from tasty and run the result
-    step3.checkCompile() // Decompile from tasty
-
-    val step4 = compileFilesInDir(decompilationDir, defaultOptions, blacklist = Set()).keepOutput
-    step4.checkRuns() // Recompile and run decompiled code
-
-    (step1 + step2 + step3 + step4).delete()
-  }
-
-  private implicit class tastyCompilationTuples(tup: (CompilationTest, CompilationTest)) {
-    def +(that: (CompilationTest, CompilationTest)): (CompilationTest, CompilationTest) =
-      (tup._1 + that._1, tup._2 + that._2)
+      ),
+      recompilationBlacklist = Set()
+    ).checkRuns()
   }
 }
 
diff --git a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
index debb4bdc5186..497d68138f50 100644
--- a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
+++ b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
@@ -2,12 +2,12 @@ package dotty
 package tools
 package vulpix
 
-import java.io.{ File => JFile }
+import java.io.{File => JFile}
 import java.text.SimpleDateFormat
 import java.util.HashMap
 import java.nio.file.StandardCopyOption.REPLACE_EXISTING
-import java.nio.file.{ Files, Path, Paths, NoSuchFileException }
-import java.util.concurrent.{ Executors => JExecutors, TimeUnit, TimeoutException }
+import java.nio.file.{Files, NoSuchFileException, Path, Paths}
+import java.util.concurrent.{TimeUnit, TimeoutException, Executors => JExecutors}
 
 import scala.io.Source
 import scala.util.control.NonFatal
@@ -15,14 +15,14 @@ import scala.util.Try
 import scala.collection.mutable
 import scala.util.matching.Regex
 import scala.util.Random
-
 import dotc.core.Contexts._
-import dotc.reporting.{ Reporter, TestReporter }
+import dotc.reporting.{Reporter, TestReporter}
 import dotc.reporting.diagnostic.MessageContainer
 import dotc.interfaces.Diagnostic.ERROR
 import dotc.util.DiffUtil
-import dotc.{ Driver, Compiler }
+import dotc.{Compiler, Driver}
 import dotc.decompiler
+import dotty.tools.vulpix.TestConfiguration.defaultOptions
 
 /** A parallel testing suite whose goal is to integrate nicely with JUnit
  *
@@ -1258,8 +1258,8 @@ trait ParallelTesting extends RunnerOrchestration { self =>
    *  Tests in the first part of the tuple must be executed before the second.
    *  Both testsRequires explicit delete().
    */
-  def compileTastyInDir(f: String, flags0: TestFlags, blacklist: Set[String])(
-      implicit testGroup: TestGroup): (CompilationTest, CompilationTest, CompilationTest, String) = {
+  def compileTastyInDir(f: String, flags0: TestFlags, blacklist: Set[String], recompilationBlacklist: Set[String])(
+      implicit testGroup: TestGroup): TastyCompilationTest = {
     val outDir = defaultOutputDir + testGroup + "/"
     val flags = flags0 and "-Yretain-trees"
     val sourceDir = new JFile(f)
@@ -1287,14 +1287,50 @@ trait ParallelTesting extends RunnerOrchestration { self =>
 
     val decompilationDir = outDir + sourceDir.getName + "_decompiled"
 
-    (
+    new TastyCompilationTest(
       generateClassFiles.keepOutput,
       new CompilationTest(targets).keepOutput,
       new CompilationTest(targets2).keepOutput,
-      decompilationDir
+      recompilationBlacklist,
+      decompilationDir,
+      shouldDelete = true
     )
   }
 
+  class TastyCompilationTest(step1: CompilationTest, step2: CompilationTest, step3: CompilationTest,
+      recompilationBlacklist: Set[String], decompilationDir: String, shouldDelete: Boolean)(implicit testGroup: TestGroup) {
+
+    def keepOutput: TastyCompilationTest =
+      new TastyCompilationTest(step1, step2, step3, recompilationBlacklist, decompilationDir, shouldDelete)
+
+    def checkCompile()(implicit summaryReport: SummaryReporting): this.type = {
+      step1.checkCompile() // Compile all files to generate the class files with tasty
+      step2.checkCompile() // Compile from tasty
+      step3.checkCompile() // Decompile from tasty
+
+      val step4 = compileFilesInDir(decompilationDir, defaultOptions, recompilationBlacklist).keepOutput
+      step4.checkCompile() // Recompile decompiled code
+
+      if (shouldDelete)
+        (step1 + step2 + step3 + step4).delete()
+
+      this
+    }
+
+    def checkRuns()(implicit summaryReport: SummaryReporting): this.type = {
+      step1.checkCompile() // Compile all files to generate the class files with tasty
+      step2.checkRuns() // Compile from tasty
+      step3.checkCompile() // Decompile from tasty
+
+      val step4 = compileFilesInDir(decompilationDir, defaultOptions, recompilationBlacklist).keepOutput
+      step4.checkRuns() // Recompile decompiled code
+
+      if (shouldDelete)
+        (step1 + step2 + step3 + step4).delete()
+
+      this
+    }
+  }
 
   /** This function behaves similar to `compileFilesInDir` but it ignores
    *  sub-directories and as such, does **not** perform separate compilation

From 6971c0db945c065d0d6ca849f377c6d51641ea35 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Mon, 7 May 2018 08:15:34 +0200
Subject: [PATCH 8/9] Fix double space in module diefinition printing

---
 compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala | 6 ++++--
 tests/pos/simpleCaseObject.decompiled                       | 2 +-
 tests/run/puzzle.decompiled                                 | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index 73a077bbe803..983cdab535e3 100644
--- a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -640,7 +640,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     val tparamsTxt = withEnclosingDef(constr) { tparamsText(tparams) }
     val primaryConstrs = if (constr.rhs.isEmpty) Nil else constr :: Nil
     val prefix: Text =
-      if (constr.symbol.owner.is(Module)) " "
+      if (constr.symbol.owner.is(Module)) ""
       else if (vparamss.isEmpty || primaryConstrs.nonEmpty) tparamsTxt
       else {
         var modsText = modText(constr.mods, "")
@@ -661,7 +661,9 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       params ::: rest
     } else impl.body
 
-    val bodyText = "{" ~~ selfText ~~ toTextGlobal(primaryConstrs ::: body, "\n") ~ "}"
+    val bodyText =
+      (if (constr.symbol.owner.is(Module)) " {" else "{") ~~
+      selfText ~~ toTextGlobal(primaryConstrs ::: body, "\n") ~ "}"
 
     prefix ~ (keywordText(" extends") provided (!ofNew && parents.nonEmpty)) ~~ parentsText ~~ bodyText
   }
diff --git a/tests/pos/simpleCaseObject.decompiled b/tests/pos/simpleCaseObject.decompiled
index cffa8ea17e3d..66dac789c7b2 100644
--- a/tests/pos/simpleCaseObject.decompiled
+++ b/tests/pos/simpleCaseObject.decompiled
@@ -1,6 +1,6 @@
 /** Decompiled from out/posTestFromTasty/pos/simpleCaseObject/foo/Foo.class */
 package foo {
-  case object Foo  {
+  case object Foo {
     override def hashCode(): Int = 1045991777
     override def toString(): String = "Foo"
     override def canEqual(that: Any): Boolean =
diff --git a/tests/run/puzzle.decompiled b/tests/run/puzzle.decompiled
index 220e4f4a0264..2f8c2d50577f 100644
--- a/tests/run/puzzle.decompiled
+++ b/tests/run/puzzle.decompiled
@@ -1,5 +1,5 @@
 /** Decompiled from out/runTestFromTasty/run/puzzle/Test.class */
-object Test  {
+object Test {
   def main(args: Array[String]): Unit =
     {
       println(if false then 5.0 else 53.0)

From 3301cf4a925b4da4efa98b68bbf7dca8b446f31c Mon Sep 17 00:00:00 2001
From: Allan Renucci <allan.renucci@gmail.com>
Date: Tue, 8 May 2018 17:43:38 +0200
Subject: [PATCH 9/9] Move more logic from RefinedPrinter to DecompilerPrinter

RefinedPrinter cannot make use of symbols in order to be able to print
after all phases (e.g. Parser).
---
 .../dotc/printing/DecompilerPrinter.scala     | 20 ++++++++++++-------
 .../tools/dotc/printing/RefinedPrinter.scala  | 20 +++++++------------
 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
index 5f2cfb254804..969276e732bc 100644
--- a/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala
@@ -1,7 +1,7 @@
 package dotty.tools.dotc.printing
 
 import dotty.tools.dotc.ast.Trees._
-import dotty.tools.dotc.ast.untpd.{PackageDef, Template, TypeDef}
+import dotty.tools.dotc.ast.untpd.{Tree, PackageDef, Template, TypeDef}
 import dotty.tools.dotc.ast.{Trees, untpd}
 import dotty.tools.dotc.printing.Texts._
 import dotty.tools.dotc.core.Contexts._
@@ -54,16 +54,22 @@ class DecompilerPrinter(_ctx: Context) extends RefinedPrinter(_ctx) {
     decl ~~ typeText(nameIdText(tree)) ~ withEnclosingDef(tree) { toTextTemplate(impl) } ~ ""
   }
 
-  override protected def selfToText(impl: Template): Text =
-    super.selfToText(impl).provided(!impl.constr.symbol.owner.is(Module))
-
   override protected def toTextTemplate(impl: Template, ofNew: Boolean = false): Text = {
-    def isSyntheticParent(sym: Symbol): Boolean = {
+    def isSynthetic(parent: Tree): Boolean = {
+      val sym = parent.symbol
       sym.maybeOwner == defn.ObjectClass ||
       (sym == defn.ProductClass && impl.symbol.owner.is(Case))
     }
-    val impl1 = impl.copy(parents = impl.parents.filterNot(p => isSyntheticParent(p.symbol)))
-    super.toTextTemplate(impl1, ofNew)
+    val parents = impl.parents.filterNot(isSynthetic)
+
+    // We don't print self type and constructor for objects
+    val isObject = impl.constr.symbol.owner.is(Module)
+    if (isObject) {
+      val parentsText = keywordText(" extends") ~~ Text(parents.map(constrText), keywordStr(" with "))
+      val bodyText = " {" ~~ toTextGlobal(impl.body, "\n") ~ "}"
+      parentsText.provided(parents.nonEmpty) ~ bodyText
+    }
+    else super.toTextTemplate(impl.copy(parents = parents), ofNew)
   }
 
   override protected def typeApplyText[T >: Untyped](tree: TypeApply[T]): Text = {
diff --git a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index 983cdab535e3..ff945431e5c6 100644
--- a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -640,8 +640,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     val tparamsTxt = withEnclosingDef(constr) { tparamsText(tparams) }
     val primaryConstrs = if (constr.rhs.isEmpty) Nil else constr :: Nil
     val prefix: Text =
-      if (constr.symbol.owner.is(Module)) ""
-      else if (vparamss.isEmpty || primaryConstrs.nonEmpty) tparamsTxt
+      if (vparamss.isEmpty || primaryConstrs.nonEmpty) tparamsTxt
       else {
         var modsText = modText(constr.mods, "")
         if (!modsText.isEmpty) modsText = " " ~ modsText
@@ -649,7 +648,10 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         withEnclosingDef(constr) { addVparamssText(tparamsTxt ~~ modsText, vparamss) }
       }
     val parentsText = Text(parents map constrText, keywordStr(" with "))
-    val selfText = selfToText(impl)
+    val selfText = {
+      val selfName = if (self.name == nme.WILDCARD) keywordStr("this") else self.name.toString
+      (selfName ~ optText(self.tpt)(": " ~ _) ~ " =>").close
+    }.provided(!self.isEmpty)
     val body = if (ctx.settings.YtestPickler.value) {
       // Pickling/unpickling reorders the body members, so we need to homogenize
       val (params, rest) = impl.body partition {
@@ -661,17 +663,9 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       params ::: rest
     } else impl.body
 
-    val bodyText =
-      (if (constr.symbol.owner.is(Module)) " {" else "{") ~~
-      selfText ~~ toTextGlobal(primaryConstrs ::: body, "\n") ~ "}"
-
-    prefix ~ (keywordText(" extends") provided (!ofNew && parents.nonEmpty)) ~~ parentsText ~~ bodyText
-  }
+    val bodyText = " {" ~~ selfText ~~ toTextGlobal(primaryConstrs ::: body, "\n") ~ "}"
 
-  protected def selfToText(impl: Template): Text = {
-    val self = impl.self
-    val selfName = if (self.name == nme.WILDCARD) keywordStr("this") else self.name.toString
-    (selfName ~ optText(self.tpt)(": " ~ _) ~ " =>").close provided (!self.isEmpty)
+    prefix ~ keywordText(" extends").provided(!ofNew && parents.nonEmpty) ~~ parentsText ~ bodyText
   }
 
   protected def templateText(tree: TypeDef, impl: Template): Text = {