Fix InferExpectedTypeSuite.unapply

[Cherry-picked 0b4e677]

Author: dwijnand

presentation-compiler/src/main/dotty/tools/pc/InferExpectedType.scala

@@ -11,6 +11,8 @@ import dotty.tools.dotc.core.Types.*
 import dotty.tools.dotc.core.Types.Type
 import dotty.tools.dotc.interactive.Interactive
 import dotty.tools.dotc.interactive.InteractiveDriver
+import dotty.tools.dotc.typer.Applications.UnapplyArgs
+import dotty.tools.dotc.util.NoSourcePosition
 import dotty.tools.dotc.util.SourceFile
 import dotty.tools.dotc.util.Spans.Span
 import dotty.tools.pc.IndexedContext
@@ -89,6 +91,10 @@ object InterCompletionType:
       // val _: T = @@
       // def _: T = @@
       case (defn: ValOrDefDef) :: rest if !defn.tpt.tpe.isErroneous => Some(defn.tpt.tpe)
+      case UnApply(fun, _, pats) :: _ =>
+        val ind = pats.indexWhere(_.span.contains(span))
+        if ind < 0 then None
+        else Some(UnapplyArgs(fun.tpe.finalResultType, fun, pats, NoSourcePosition).argTypes(ind))
       // f(@@)
       case (app: Apply) :: rest =>
         val param =

presentation-compiler/test/dotty/tools/pc/tests/InferExpectedTypeSuite.scala

@@ -193,7 +193,6 @@ class InferExpectedTypeSuite extends BasePCSuite:
          |""".stripMargin
     )
 
-  @Ignore("Unapply is not handled correctly.")
   @Test def unapply =
     check(
       """|val _ =