Add Reflection constructors for SuperType, RecursiveType and RecursiveThis

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -1165,7 +1165,7 @@ object Types {
      *  these types as a set, otherwise the empty set.
      *  Overridden and cached in OrType.
      *  @param widenOK  If type proxies that are upperbounded by types with atoms
-     *                  have the same atoms. 
+     *                  have the same atoms.
      */
     def atoms(widenOK: Boolean = false)(implicit ctx: Context): Set[Type] = dealias match {
       case tp: SingletonType =>
@@ -2544,7 +2544,7 @@ object Types {
   final class CachedSuperType(thistpe: Type, supertpe: Type) extends SuperType(thistpe, supertpe)
 
   object SuperType {
-    def apply(thistpe: Type, supertpe: Type)(implicit ctx: Context): Type = {
+    def apply(thistpe: Type, supertpe: Type)(implicit ctx: Context): SuperType = {
       assert(thistpe != NoPrefix)
       unique(new CachedSuperType(thistpe, supertpe))
     }

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

@@ -1274,6 +1274,9 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
       case _ => None
   }
 
+  def SuperType_apply(thistpe: Type, supertpe: Type)(given ctx: Context): SuperType =
+    Types.SuperType(thistpe, supertpe)
+
   def SuperType_thistpe(self: SuperType)(given Context): Type = self.thistpe
   def SuperType_supertpe(self: SuperType)(given Context): Type = self.supertpe
 
@@ -1431,8 +1434,13 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
       case _ => None
   }
 
+  def RecursiveType_apply(parentExp: RecursiveType => Type)(given ctx: Context): RecursiveType =
+    Types.RecType(parentExp)
+
   def RecursiveType_underlying(self: RecursiveType)(given Context): Type = self.underlying.stripTypeVar
 
+  def RecursiveThis_recThis(self: RecursiveType)(given Context): RecursiveThis = self.recThis
+
   type LambdaType[ParamInfo] = Types.LambdaType { type PInfo = ParamInfo }
 
   type MethodType = Types.MethodType

library/src/scala/tasty/Reflection.scala

@@ -1738,6 +1738,9 @@ class Reflection(private[scala] val internal: CompilerInterface) { self =>
   given (given Context): IsInstanceOf[SuperType] = internal.isInstanceOfSuperType
 
   object SuperType {
+    def apply(thistpe: Type, supertpe: Type)(given ctx: Context): SuperType =
+      internal.SuperType_apply(thistpe, supertpe)
+
     def unapply(x: SuperType)(given ctx: Context): Option[(Type, Type)] =
       Some((x.thistpe, x.supertpe))
   }
@@ -1887,11 +1890,25 @@ class Reflection(private[scala] val internal: CompilerInterface) { self =>
   given (given Context): IsInstanceOf[RecursiveType] = internal.isInstanceOfRecursiveType
 
   object RecursiveType {
+
+    /** Create a RecType, normalizing its contents. This means:
+     *
+     *   1. Nested Rec types on the type's spine are merged with the outer one.
+     *   2. Any refinement of the form `type T = z.T` on the spine of the type
+     *      where `z` refers to the created rec-type is replaced by
+     *      `type T`. This avoids infinite recursions later when we
+     *      try to follow these references.
+     */
+    def apply(parentExp: RecursiveType => Type)(given ctx: Context): RecursiveType =
+      internal.RecursiveType_apply(parentExp)
+
     def unapply(x: RecursiveType)(given ctx: Context): Option[Type] = Some(x.underlying)
+
   }
 
   extension RecursiveTypeOps on (self: RecursiveType) {
     def underlying(given ctx: Context): Type = internal.RecursiveType_underlying(self)
+    def recThis(given Context): RecursiveThis = internal.RecursiveThis_recThis(self)
   }
 
   given (given Context): IsInstanceOf[MethodType] = internal.isInstanceOfMethodType

library/src/scala/tasty/reflect/CompilerInterface.scala

@@ -923,6 +923,8 @@ trait CompilerInterface {
 
   def isInstanceOfSuperType(given ctx: Context): IsInstanceOf[SuperType]
 
+  def SuperType_apply(thistpe: Type, supertpe: Type)(given ctx: Context): SuperType
+
   def SuperType_thistpe(self: SuperType)(given ctx: Context): Type
   def SuperType_supertpe(self: SuperType)(given ctx: Context): Type
 
@@ -1024,8 +1026,20 @@ trait CompilerInterface {
 
   def isInstanceOfRecursiveType(given ctx: Context): IsInstanceOf[RecursiveType]
 
+  /** Create a RecType, normalizing its contents. This means:
+   *
+   *   1. Nested Rec types on the type's spine are merged with the outer one.
+   *   2. Any refinement of the form `type T = z.T` on the spine of the type
+   *      where `z` refers to the created rec-type is replaced by
+   *      `type T`. This avoids infinite recursions later when we
+   *      try to follow these references.
+   */
+  def RecursiveType_apply(parentExp: RecursiveType => Type)(given ctx: Context): RecursiveType
+
   def RecursiveType_underlying(self: RecursiveType)(given ctx: Context): Type
 
+  def RecursiveThis_recThis(self: RecursiveType)(given Context): RecursiveThis
+
   // TODO can we add the bound back without an cake?
   // TODO is LambdaType really needed? ParamRefExtractor could be split into more precise extractors
   /** Common abstraction for lambda types (MethodType, PolyType and TypeLambda). */