revert: Only leave added tests

Author: tgodzik

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -113,7 +113,6 @@ object SpaceEngine {
   def isSubspace(a: Space, b: Space)(using Context): Boolean = a.isSubspace(b)
   def canDecompose(typ: Typ)(using Context): Boolean         = typ.canDecompose
   def decompose(typ: Typ)(using Context): List[Typ]          = typ.decompose
-  def nullSpace(using Context): Space = Typ(ConstantType(Constant(null)), decomposed = false)
 
   /** Simplify space such that a space equal to `Empty` becomes `Empty` */
   def computeSimplify(space: Space)(using Context): Space = trace(i"simplify($space)")(space match {
@@ -904,11 +903,6 @@ object SpaceEngine {
       then project(OrType(selTyp, ConstantType(Constant(null)), soft = false))
       else project(selTyp)
     )
-    def projectPat(pat: Tree): Space =
-      // Project toplevel wildcard pattern to nullable
-      if isNullable && isWildcardArg(pat) then Or(project(pat) :: nullSpace :: Nil)
-      else project(pat)
-
     var i        = 0
     val len      = cases.length
     var prevs    = List.empty[Space]
@@ -917,7 +911,7 @@ object SpaceEngine {
     while (i < len) {
       val CaseDef(pat, guard, _) = cases(i)
 
-      val curr = trace(i"project($pat)")(projectPat(pat))
+      val curr = trace(i"project($pat)")(project(pat))
 
       val covered = trace("covered")(simplify(intersect(curr, targetSpace)))
 

tests/patmat/null.check

@@ -1,4 +1,4 @@
 6: Pattern Match
 13: Pattern Match
-20: Pattern Match
-21: Match case Unreachable
+20: Match case Unreachable
+21: Pattern Match

tests/warn/i15503d.scala

@@ -16,7 +16,7 @@ val a = Sum(S(S(Z)),Z) match {
   case Sum(a@S(b@S(_)), Z) => a // warn
   case Sum(a@S(b@(S(_))), Z) => Sum(a,b) // warn unreachable
   case Sum(_,_) => Z // OK
-  case _ => Z
+  case _ => Z // warn unreachable
 }
 
 // todo : This should pass in the future

tests/warn/t2755.scala

@@ -19,7 +19,7 @@ object Test {
     case x: Array[String]   => x.size
     case x: Array[AnyRef]   => 5
     case x: Array[?]        => 6
-    case _                  => 7
+    case _                  => 7  // warn: only null is matched
   }
   def f3[T](a: Array[T]) = a match {
     case x: Array[Int]      => x(0)
@@ -28,7 +28,7 @@ object Test {
     case x: Array[String]   => x.size
     case x: Array[AnyRef]   => 5
     case x: Array[?]        => 6
-    case _                  => 7
+    case _                  => 7  // warn: only null is matched
   }