Remove unused code

Author: noti0na1

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

@@ -224,7 +224,6 @@ class Definitions {
     @tu lazy val Compiletime_constValueOpt: Symbol = CompiletimePackageObject.requiredMethod("constValueOpt")
     @tu lazy val Compiletime_code         : Symbol = CompiletimePackageObject.requiredMethod("code")
     @tu lazy val Compiletime_summonFrom   : Symbol = CompiletimePackageObject.requiredMethod("summonFrom")
-    @tu lazy val Compiletime_notNull      : Symbol = CompiletimePackageObject.requiredMethod("$notNull")
   @tu lazy val CompiletimeTestingPackageObject: Symbol = ctx.requiredModule("scala.compiletime.testing.package")
     @tu lazy val CompiletimeTesting_typeChecks: Symbol = CompiletimeTestingPackageObject.requiredMethod("typeChecks")
     @tu lazy val CompiletimeTesting_typeCheckErrors: Symbol = CompiletimeTestingPackageObject.requiredMethod("typeCheckErrors")

compiler/src/dotty/tools/dotc/typer/ConstFold.scala

@@ -21,16 +21,6 @@ object ConstFold {
   /** If tree is a constant operation, replace with result. */
   def apply[T <: Tree](tree: T)(implicit ctx: Context): T = finish(tree) {
     tree match {
-      // TODO: fix it later
-      // case CompareNull(operand, testEqual)
-      // if ctx.explicitNulls && !operand.typeOpt.isNullableUnion =>
-      //   println(tree.show)
-      //   Constant(!testEqual)
-      // case CompareNull(TrackedRef(ref), testEqual)
-      // if ctx.settings.YexplicitNulls.value && ctx.notNullInfos.impliesNotNull(ref) =>
-      //   //throw new NullPointerException()
-      //   // TODO maybe drop once we have general Nullability?
-      //   Constant(!testEqual)
       case Apply(Select(xt, op), yt :: Nil) =>
         xt.tpe.widenTermRefExpr.normalized match
           case ConstantType(x) =>

library/src/scala/compiletime/package.scala

@@ -63,19 +63,4 @@ package object compiletime {
    *      }
    */
   type S[N <: Int] <: Int
-
-  /** Strip the Null type from `x`
-   *
-   *  ```
-   *  val x: String|Null = ???
-   *  val _: String = $notNull[String, x.type & String](x)
-   *
-   *  var y: String|Null = ???
-   *  val _: String = $notNull[String, String](x)
-   *  ```
-   *
-   *  Since `$notNull` is erased later, if `x.type` is a stable path,
-   *  the type of `$notNull(x)` is also a stable path.
-   */
-  inline def $notNull[A, B](x: => A | Null): B =  x.asInstanceOf
 }