Fix Tasty reflect with varargs in unapply

Author: nicolasstucki

compiler/src/dotty/tools/dotc/tastyreflect/TastyImpl.scala

@@ -587,10 +587,14 @@ class TastyImpl(val rootContext: Contexts.Context) extends scala.tasty.Tasty { s
 
     object Unapply extends UnapplyExtractor {
       def unapply(x: Pattern)(implicit ctx: Context): Option[(Term, List[Term], List[Pattern])] = x match {
-        case Trees.UnApply(fun, implicits, patterns) => Some((fun, implicits, patterns))
-        case Trees.Typed(Trees.UnApply(fun, implicits, patterns), _) => Some((fun, implicits, patterns))
+        case Trees.UnApply(fun, implicits, patterns) => Some((fun, implicits, effectivePatterns(patterns)))
+        case Trees.Typed(Trees.UnApply(fun, implicits, patterns), _) => Some((fun, implicits, effectivePatterns(patterns)))
         case _ => None
       }
+      private def effectivePatterns(patterns: List[Pattern]): List[Pattern] = patterns match {
+        case patterns0 :+ Trees.SeqLiteral(elems, _) => patterns0 ::: elems
+        case _ => patterns
+      }
     }
 
     object Alternative extends AlternativeExtractor {

compiler/test/dotc/run-decompilation.blacklist

@@ -40,10 +40,6 @@ t4601.scala
 t6633.scala
 arrays.scala
 
-# scala.MatchError: SeqLiteral in pattern
-i3248.scala
-t6541.scala
-
 # Stackoverflow
 t10594.scala