fixes scala#8514, TypeApi#baseType exposed into Tasty

Author: pshirshov

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

@@ -1205,6 +1205,9 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
   def Type_baseClasses(self: Type)(using Context): List[Symbol] =
     self.baseClasses
 
+  def Type_baseType(self: Type)(cls: Symbol)(using Context): Type =
+    self.baseType(cls)
+
   def Type_derivesFrom(self: Type)(cls: Symbol)(using Context): Boolean =
     self.derivesFrom(cls)
 

library/src/scala/tasty/Reflection.scala

@@ -1812,6 +1812,17 @@ class Reflection(private[scala] val internal: CompilerInterface) { self =>
       /** The base classes of this type with the class itself as first element. */
       def baseClasses(using ctx: Context): List[Symbol] = internal.Type_baseClasses(self)
 
+
+    /** The least type instance of given class which is a super-type
+     *  of this type.  Example:
+     *  {{{
+     *    class D[T]
+     *    class C extends p.D[Int]
+     *    ThisType(C).baseType(D) = p.D[Int]
+     * }}}
+     */
+      def baseType(using ctx: Context)(cls: Symbol): Type = internal.Type_baseType(self)(cls)
+
       /** Is this type an instance of a non-bottom subclass of the given class `cls`? */
       def derivesFrom(cls: Symbol)(using ctx: Context): Boolean =
         internal.Type_derivesFrom(self)(cls)

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

@@ -876,6 +876,16 @@ trait CompilerInterface {
   /** The base classes of this type with the class itself as first element. */
   def Type_baseClasses(self: Type)(using ctx: Context): List[Symbol]
 
+  /** The least type instance of given class which is a super-type
+    *  of this type.  Example:
+    *  {{{
+    *    class D[T]
+    *    class C extends p.D[Int]
+    *    ThisType(C).baseType(D) = p.D[Int]
+    * }}}
+    */
+  def Type_baseType(self: Type)(cls: Symbol)(using ctx: Context): Type
+
   /** Is this type an instance of a non-bottom subclass of the given class `cls`? */
   def Type_derivesFrom(self: Type)(cls: Symbol)(using ctx: Context): Boolean