Fix scala#13223: Disalow ? in match types pats/bodies

Author: OlivierBlanvillain

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -2609,10 +2609,10 @@ object Parsers {
     def typeCaseClause(): CaseDef = atSpan(in.offset) {
       val pat = inSepRegion(InCase) {
         accept(CASE)
-        infixType()
+        rejectWildcardType(infixType())
       }
       CaseDef(pat, EmptyTree, atSpan(accept(ARROW)) {
-        val t = typ()
+        val t = rejectWildcardType(typ())
         newLinesOptWhenFollowedBy(CASE)
         t
       })

tests/neg/12261.scala

@@ -0,0 +1,11 @@
+type M0[X] = X match {
+  case ? => String // error: Unbound wildcard type
+}
+
+type M1[X] = X match {
+  case Any => _ // error: Unbound wildcard type
+}
+
+type M2[X] = X match {
+  case Any => ? // error: Unbound wildcard type
+}

tests/pos/9239.scala

@@ -24,5 +24,5 @@ object ABug:
     N match
       case Zero => One
       case One => One
-      case ? => ![--[N]] × (N)
+      case _ => ![--[N]] × (N)
       case ? :: ? => ![--[N]] × (N)