Prevent deprecation of _ in type patterns

Author: ausmarton

Diff for: compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -1860,9 +1860,6 @@ object Parsers {
           val start = in.skipToken()
           Ident(tpnme.USCOREkw).withSpan(Span(start, in.lastOffset, start))
         else
-          if sourceVersion.isAtLeast(future) then
-            deprecationWarning(em"`_` is deprecated for wildcard arguments of types: use `?` instead")
-            patch(source, Span(in.offset, in.offset + 1), "?")
           val start = in.skipToken()
           typeBounds().withSpan(Span(start, in.lastOffset, start))
       // Allow symbols -_ and +_ through for compatibility with code written using kind-projector in Scala 3 underscore mode.

Diff for: tests/pos-with-compiler-cc/dotc/parsing/Parsers.scala

@@ -1730,9 +1730,6 @@ object Parsers {
           val start = in.skipToken()
           Ident(tpnme.USCOREkw).withSpan(Span(start, in.lastOffset, start))
         else
-          if sourceVersion.isAtLeast(future) then
-            deprecationWarning(em"`_` is deprecated for wildcard arguments of types: use `?` instead")
-            patch(source, Span(in.offset, in.offset + 1), "?")
           val start = in.skipToken()
           typeBounds().withSpan(Span(start, in.lastOffset, start))
       // Allow symbols -_ and +_ through for compatibility with code written using kind-projector in Scala 3 underscore mode.

Diff for: tests/pos/i18808.scala

@@ -0,0 +1,8 @@
+//> using options -Werror
+import language.future
+
+type F[X] = X match
+  case List[_] => Int
+
+type G[X] = X match
+  case List[?] => Int