Merge pull request #4687 from dotty-staging/fix-tasty-constant-type

Add Tasty.Constant.ClassTag

Author: nicolasstucki

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

@@ -940,6 +940,13 @@ object TastyImpl extends scala.tasty.Tasty {
       }
     }
 
+    object ClassTag extends ClassTagExtractor {
+      def unapply(x: Constant): Option[Type] = x match {
+        case x: Constants.Constant if x.tag == Constants.ClazzTag => Some(x.typeValue)
+        case _ => None
+      }
+    }
+
   }
 
   // ===== Signature ================================================

library/src/scala/tasty/Tasty.scala

@@ -731,6 +731,10 @@ abstract class Tasty { tasty =>
       def unapply(x: Constant): Option[String]
     }
 
+    val ClassTag: ClassTagExtractor
+    abstract class ClassTagExtractor {
+      def unapply(x: Constant): Option[Type]
+    }
   }
 
   // ===== Signature ================================================

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

@@ -150,6 +150,7 @@ class ShowExtractors[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       case Constant.Float(value) => this += "Constant.Float(" += value += ")"
       case Constant.Double(value) => this += "Constant.Double(" += value += ")"
       case Constant.String(value) => this += "Constant.String(\"" += value += "\")"
+      case Constant.ClassTag(value) => this += "Constant.ClassTag(" += value += ")"
     }
 
     def visitType(x: TypeOrBounds): Buffer = x match {

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

@@ -237,7 +237,7 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
 
       case Term.Select(qual, name, sig) =>
         printTree(qual)
-        if (name != "<init>")
+        if (name != "<init>" && name != "package")
           this += "." += name
         this
 
@@ -664,6 +664,10 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       case Constant.Double(v) => this += v
       case Constant.Char(v) => this += '\'' += escapedChar(v) += '\''
       case Constant.String(v) => this += '"' += escapedString(v) += '"'
+      case Constant.ClassTag(v) =>
+        this += "classOf["
+        printType(v)
+        this += "]"
     }
 
     def printTypeOrBoundsTree(tpt: TypeOrBoundsTree): Buffer = tpt match {

tests/pos/i566.decompiled

@@ -0,0 +1,6 @@
+/** Decompiled from out/posTestFromTasty/pos/i566/Test.class */
+class Test() {
+  type T = scala.Predef.String
+  type U
+  scala.reflect.classTag[Test.this.T](scala.reflect.ClassTag.apply[Test.this.T](classOf[java.lang.String]))
+}