Fix #9812: Do not widen types during quote reification

compiler/src/dotty/tools/dotc/transform/ReifyQuotes.scala

@@ -163,16 +163,10 @@ class ReifyQuotes extends MacroTransform {
       }
 
       def pickleAsTasty() = {
-        val meth =
-          if (isType) ref(defn.Unpickler_unpickleType).appliedToType(originalTp)
-          else
-            val tpe =
-              if originalTp =:= defn.NilModule.termRef then originalTp // Workaround #4987
-              else originalTp.widen.dealias
-            ref(defn.Unpickler_unpickleExpr).appliedToType(tpe)
+        val meth = if isType then defn.Unpickler_unpickleType else defn.Unpickler_unpickleExpr
         val pickledQuoteStrings = liftList(PickledQuotes.pickleQuote(body).map(x => Literal(Constant(x))), defn.StringType)
         val splicesList = liftList(splices, defn.FunctionType(1).appliedTo(defn.SeqType.appliedTo(defn.AnyType), defn.AnyType))
-        meth.appliedTo(pickledQuoteStrings, splicesList)
+        ref(meth).appliedToType(originalTp).appliedTo(pickledQuoteStrings, splicesList)
       }
 
       def taggedType(sym: Symbol) = ref(defn.InternalQuotedTypeModule).select(sym.name.toTermName)

tests/pos-macros/i9812.scala

@@ -0,0 +1,8 @@
+// compile with -Ycheck:reifyQuotes -Ystop-after:reifyQuotes
+import quoted._
+
+sealed abstract class SomeEnum
+object SomeEnum:
+  final val Foo = new SomeEnum {}
+
+def quoteFoo: QuoteContext ?=> Expr[SomeEnum.Foo.type] = '{SomeEnum.Foo}