Handle MatchTypeTrees in ExtractAPI

Also, fix creators for typed/untyped MatchTypeTrees

Author: odersky

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -165,6 +165,9 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   def LambdaTypeTree(tparams: List[TypeDef], body: Tree)(implicit ctx: Context): LambdaTypeTree =
     ta.assignType(untpd.LambdaTypeTree(tparams, body), tparams, body)
 
+  def MatchTypeTree(bound: Tree, selector: Tree, cases: List[CaseDef])(implicit ctx: Context): MatchTypeTree =
+    ta.assignType(untpd.MatchTypeTree(bound, selector, cases), bound, selector, cases)
+
   def TypeBoundsTree(lo: Tree, hi: Tree)(implicit ctx: Context): TypeBoundsTree =
     ta.assignType(untpd.TypeBoundsTree(lo, hi), lo, hi)
 

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -1383,7 +1383,7 @@ class TreeUnpickler(reader: TastyReader,
             val fst = readUntyped()
             val (bound, scrut) =
               if (nextUnsharedTag == CASEDEF) (EmptyTree, fst) else (fst, readUntyped())
-            MatchTypeTree(bound, scrut, readCases(end))
+            untpd.MatchTypeTree(bound, scrut, readCases(end))
           case TYPEBOUNDStpt =>
             val lo = readUntyped()
             val hi = ifBefore(end)(readUntyped(), lo)

compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala

@@ -166,7 +166,7 @@ private class ExtractAPICollector(implicit val ctx: Context) extends ThunkHolder
     api.Annotation.of(api.Constant.of(Constants.emptyType, name), Array())
   val orMarker = marker("Or")
   val byNameMarker = marker("ByName")
-
+  val matchMarker = marker("Match")
 
   /** Extract the API representation of a source file */
   def apiSource(tree: Tree): Seq[api.ClassLike] = {
@@ -507,6 +507,9 @@ private class ExtractAPICollector(implicit val ctx: Context) extends ThunkHolder
         withMarker(s, orMarker)
       case ExprType(resultType) =>
         withMarker(apiType(resultType), byNameMarker)
+      case MatchType(bound, scrut, cases) =>
+        val s = combineApiTypes(apiType(bound) :: apiType(scrut) :: cases.map(apiType): _*)
+        withMarker(s, matchMarker)
       case ConstantType(constant) =>
         api.Constant.of(apiType(constant.tpe), constant.stringValue)
       case AnnotatedType(tpe, annot) =>