Dealias before looking for the symbol

Author: natsukagami

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1101,8 +1101,8 @@ class Definitions {
         RefinedType(fnType, nme.apply, mt)
       else fnType
     def unapply(ft: Type)(using Context): Option[(List[Type], Type, Boolean, List[Boolean])] = {
-      val tsym = ft.typeSymbol
-      if isFunctionClass(tsym) && ft.isRef(tsym) then
+      val tsym = ft.dealias.typeSymbol
+      if isFunctionSymbol(tsym) && ft.isRef(tsym) then
         val targs = ft.dealias.argInfos
         val isErased = erasedFunctionParameters(ft)
         if (targs.isEmpty) None