Fix printing extractors

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

@@ -41,7 +41,7 @@ class DecompilationPrinter extends Phase {
       new TastyPrinter(unit.pickled.head._2).printContents()
     } else {
       out.println(s"/** Decompiled from $unit */")
-      out.print(TastyImpl.showSourceCode.showTree(unit.tpdTree)(ctx))
+      out.println(TastyImpl.showSourceCode.showTree(unit.tpdTree)(ctx))
     }
   }
 }

compiler/src/dotty/tools/dotc/tastyreflect/TastyImpl.scala

@@ -454,9 +454,10 @@ object TastyImpl extends scala.tasty.Tasty {
 
   type Pattern = tpd.Tree
 
-  def PatternDeco(x: Pattern): AbstractPattern = new AbstractPattern {
-    def pos(implicit ctx: Context): Position = x.pos
-    def tpe(implicit ctx: Context): Types.Type = x.tpe.stripTypeVar
+  def PatternDeco(pattern: Pattern): AbstractPattern = new AbstractPattern {
+    def show(implicit ctx: Context, s: Show[TastyImpl.this.type]): String = s.showPattern(pattern)
+    def pos(implicit ctx: Context): Position = pattern.pos
+    def tpe(implicit ctx: Context): Types.Type = pattern.tpe.stripTypeVar
   }
 
   def patternClassTag: ClassTag[Pattern] = implicitly[ClassTag[Pattern]]

library/src/scala/tasty/Tasty.scala

@@ -324,7 +324,9 @@ abstract class Tasty { tasty =>
 
   type Pattern
 
-  trait AbstractPattern extends Typed with Positioned
+  trait AbstractPattern extends Typed with Positioned {
+    def show(implicit ctx: Context, s: Show[tasty.type]): String
+  }
   implicit def PatternDeco(x: Pattern): AbstractPattern
 
   implicit def patternClassTag: ClassTag[Pattern]

library/src/scala/tasty/util/Show.scala

@@ -8,6 +8,8 @@ abstract class Show[T <: Tasty with Singleton](val tasty: T) {
 
   def showCaseDef(caseDef: tasty.CaseDef)(implicit ctx: tasty.Context): String
 
+  def showPattern(pattern: tasty.Pattern)(implicit ctx: tasty.Context): String
+
   def showTypeOrBoundsTree(tpt: tasty.TypeOrBoundsTree)(implicit ctx: tasty.Context): String
 
   def showTypeOrBounds(tpe: tasty.TypeOrBounds)(implicit ctx: tasty.Context): String

library/src/scala/tasty/util/ShowExtractors.scala

@@ -11,6 +11,9 @@ class ShowExtractors[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
   def showCaseDef(caseDef: CaseDef)(implicit ctx: Context): String =
     new Buffer().visitCaseDef(caseDef).result()
 
+  def showPattern(pattern: tasty.Pattern)(implicit ctx: tasty.Context): String =
+    new Buffer().visitPattern(pattern).result()
+
   def showTypeOrBoundsTree(tpt: TypeOrBoundsTree)(implicit ctx: Context): String =
     new Buffer().visitTypeTree(tpt).result()
 

library/src/scala/tasty/util/ShowSourceCode.scala

@@ -10,6 +10,9 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
   def showCaseDef(caseDef: CaseDef)(implicit ctx: Context): String =
     (new Buffer).printCaseDef(caseDef).result()
 
+  def showPattern(pattern: Pattern)(implicit ctx: Context): String =
+    (new Buffer).printPattern(pattern).result()
+
   def showTypeOrBoundsTree(tpt: TypeOrBoundsTree)(implicit ctx: Context): String =
     (new Buffer).printTypeOrBoundsTree(tpt).result()
 
@@ -49,7 +52,7 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
             this += lineBreak()
             printTrees(stats1, lineBreak())
           }
-          this += lineBreak() += "}" += lineBreak()
+          this += lineBreak() += "}"
         }
 
       case Import(expr, selectors) =>
@@ -484,7 +487,13 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       this += " =>"
       indented {
         this += lineBreak()
-        printTree(body)
+        body match {
+          case Term.Block(stats, expr) =>
+            printTrees(stats, lineBreak())
+            printTree(expr)
+          case body =>
+            printTree(body)
+        }
       }
       this
     }
@@ -508,7 +517,11 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
         printPattern(pattern)
 
       case Pattern.Unapply(fun, implicits, patterns) =>
-        printTree(fun)
+        fun match {
+          case Term.Select(extractor, "unapply" | "unapplySeq", _) => printTree(extractor)
+          case Term.TypeApply(Term.Select(extractor, "unapply" | "unapplySeq", _), _) => printTree(extractor)
+          case _ => throw new MatchError(fun.show)
+        }
         this += "("
         printPatterns(patterns, ", ")
         this += ")"
@@ -517,7 +530,11 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
         printPatterns(trees, " | ")
 
       case Pattern.TypeTest(tpt) =>
-        this
+        this += "_: "
+        printTypeOrBoundsTree(tpt)
+
+      case _ =>
+        throw new MatchError(pattern.show)
 
     }
 
@@ -541,8 +558,8 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
         printTypeTree(lo)
         this += " <: "
         printTypeTree(hi)
-      case tpt@Type() =>
-        printType(tpt)
+      case tpt @ TypeTree() =>
+        printTypeTree(tpt)
     }
 
     def printTypeTree(tree: TypeTree): Buffer = tree match {
@@ -628,7 +645,9 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
 
       case Type.TermRef(name, prefix) =>
         prefix match {
-          case prefix@Type() =>
+          case Type.ThisType(Types.EmptyPackage()) =>
+            this += name
+          case prefix @ Type() =>
             printType(prefix)
             if (name != "package")
               this += "." += name
@@ -639,7 +658,7 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
 
       case Type.TypeRef(name, prefix) =>
         prefix match {
-          case NoPrefix() =>
+          case NoPrefix() | Type.ThisType(Types.EmptyPackage()) =>
           case prefix@Type() =>
             printType(prefix)
             this += "."

tests/pos/simpleExractors.decompiled

@@ -0,0 +1,35 @@
+/** Decompiled from out/posTestFromTasty/pos/simpleExractors/Bar.class */
+object Bar {
+  def unapply(arg: scala.Any): scala.Option[scala.Any] = scala.Some.apply[scala.Any](arg)
+}
+/** Decompiled from out/posTestFromTasty/pos/simpleExractors/BarSeq.class */
+object BarSeq {
+  def unapplySeq(arg: scala.Any): scala.Option[scala.Seq[scala.Any]] = scala.Some.apply[collection.immutable.List[scala.Any]](scala.List.apply[scala.Any](arg))
+}
+/** Decompiled from out/posTestFromTasty/pos/simpleExractors/Baz.class */
+object Baz {
+  def unapply[T](arg: T): scala.Option[T] = scala.Some.apply[T](arg)
+}
+/** Decompiled from out/posTestFromTasty/pos/simpleExractors/BazSeq.class */
+object BazSeq {
+  def unapplySeq[T](arg: T): scala.Option[scala.Seq[T]] = scala.Some.apply[collection.immutable.List[T]](scala.List.apply[T](arg))
+}
+/** Decompiled from out/posTestFromTasty/pos/simpleExractors/Foo.class */
+class Foo() {
+  def bar(x: scala.Any): scala.Unit = x match {
+    case Bar(a) =>
+      scala.Predef.println(a)
+    case BarSeq(a) =>
+      scala.Predef.println(a)
+    case BarSeq(a, b) =>
+      scala.Predef.println(a)
+  }
+  def baz(x: scala.Any): scala.Unit = x match {
+    case Baz(a) =>
+      scala.Predef.println(a)
+    case BazSeq(a) =>
+      scala.Predef.println(a)
+    case BazSeq(a, b) =>
+      scala.Predef.println(a)
+  }
+}

tests/pos/simpleExractors.scala

@@ -0,0 +1,28 @@
+class Foo {
+  def bar(x: Any): Unit = x match {
+    case Bar(a) => println(a)
+    case BarSeq(a) => println(a)
+    case BarSeq(a, b) => println(a)
+  }
+  def baz(x: Any): Unit = x match {
+    case Baz(a) => println(a)
+    case BazSeq(a) => println(a)
+    case BazSeq(a, b) => println(a)
+  }
+}
+
+object Bar {
+  def unapply(arg: Any): Option[Any] = Some(arg)
+}
+
+object BarSeq {
+  def unapplySeq(arg: Any): Option[Seq[Any]] = Some(List(arg))
+}
+
+object Baz {
+  def unapply[T](arg: T): Option[T] = Some(arg)
+}
+
+object BazSeq {
+  def unapplySeq[T](arg: T): Option[Seq[T]] = Some(List(arg))
+}

tests/run/tasty-custom-show/quoted_1.scala

@@ -49,6 +49,7 @@ class DummyShow[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty0) {
   import tasty._
   def showTree(tree: Tree)(implicit ctx: Context): String = "Tree"
   def showCaseDef(caseDef: CaseDef)(implicit ctx: Context): String = "CaseDef"
+  def showPattern(pattern: Pattern)(implicit ctx: Context): String = "Pattern"
   def showTypeOrBoundsTree(tpt: TypeOrBoundsTree)(implicit ctx: Context): String = "TypeOrBoundsTree"
   def showTypeOrBounds(tpe: TypeOrBounds)(implicit ctx: Context): String = "TypeOrBounds"
   def showConstant(const: Constant)(implicit ctx: Context): String = "Constant"