Revert "Normalize match type usage during implicit lookup" on 3.3.1 (#18440)

Reverts #17457.
This fix caused significant challenges in maintaining the source
compatibility. We decided not to include it in 3.3.1. It will still be a
part of 3.4 and future Scala Next versions.

It is possible that in the future, an improved version of this fix will
make it to one of 3.3.x releases.

Author: Kordyjan

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

@@ -3180,7 +3180,7 @@ class TrackingTypeComparer(initctx: Context) extends TypeComparer(initctx) {
             tp
       case Nil =>
         val casesText = MatchTypeTrace.noMatchesText(scrut, cases)
-        throw MatchTypeReductionError(em"Match type reduction $casesText")
+        throw TypeError(em"Match type reduction $casesText")
 
     inFrozenConstraint {
       // Empty types break the basic assumption that if a scrutinee and a

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

@@ -46,9 +46,6 @@ object TypeError:
     def toMessage(using Context) = msg
 end TypeError
 
-class MatchTypeReductionError(msg: Message)(using Context) extends TypeError:
-  def toMessage(using Context) = msg
-
 class MalformedType(pre: Type, denot: Denotation, absMembers: Set[Name])(using Context) extends TypeError:
   def toMessage(using Context) = em"malformed type: $pre is not a legal prefix for $denot because it contains abstract type member${if (absMembers.size == 1) "" else "s"} ${absMembers.mkString(", ")}"
 

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

@@ -636,13 +636,6 @@ trait ImplicitRunInfo:
             case t: TypeLambda =>
               for p <- t.paramRefs do partSeen += p
               traverseChildren(t)
-            case t: MatchType =>
-              traverseChildren(t)
-              traverse(try t.normalized catch case _: MatchTypeReductionError => t)
-            case MatchType.InDisguise(mt)
-                if !t.isInstanceOf[LazyRef] // skip recursive applications (eg. Tuple.Map)
-            =>
-              traverse(mt)
             case t =>
               traverseChildren(t)