Extend typedSplicePattern with type arguments

Author: zeptometer

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

@@ -130,8 +130,13 @@ trait QuotesAndSplices {
       for arg <- typedArgs if arg.symbol.is(Mutable) do // TODO support these patterns. Possibly using scala.quoted.util.Var
         report.error("References to `var`s cannot be used in higher-order pattern", arg.srcPos)
       val argTypes = typedArgs.map(_.tpe.widenTermRefExpr)
-      // TODO-18271: Generate polyType if typedTypeargs is not empty
-      val patType = if tree.args.isEmpty then pt else defn.FunctionOf(argTypes, pt)
+      // TODO-18271: Does PolyProto work here as expected?
+      val patType = (tree.typeargs.isEmpty, tree.args.isEmpty) match
+        case (false, false) => pt
+        case (false, true)  => defn.FunctionOf(argTypes, pt)
+        case (true,  false) => ProtoTypes.PolyProto(typedTypeargs, pt)
+        case (true,  true)  => ProtoTypes.PolyProto(typedTypeargs, defn.FunctionOf(argTypes, pt))
+
       val pat = typedPattern(tree.body, defn.QuotedExprClass.typeRef.appliedTo(patType))(using quotePatternSpliceContext)
       val baseType = pat.tpe.baseType(defn.QuotedExprClass)
       val argType = if baseType.exists then baseType.argTypesHi.head else defn.NothingType