fix #14025: restrict curried HK types in mirrors

Author: bishabosha

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

@@ -278,6 +278,7 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
 
     /** do all parts match the class symbol? */
     def acceptable(tp: Type, cls: Symbol): Boolean = tp match
+      case tp: HKTypeLambda if tp.resultType.isInstanceOf[HKTypeLambda] => false
       case tp: TypeProxy    => acceptable(tp.underlying, cls)
       case OrType(tp1, tp2) => acceptable(tp1, cls) && acceptable(tp2, cls)
       case _                => tp.classSymbol eq cls
@@ -330,6 +331,7 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
 
     def acceptable(tp: Type): Boolean = tp match
       case tp: TermRef => false
+      case tp: HKTypeLambda if tp.resultType.isInstanceOf[HKTypeLambda] => false
       case tp: TypeProxy => acceptable(tp.underlying)
       case OrType(tp1, tp2) => acceptable(tp1) && acceptable(tp2)
       case _            => tp.classSymbol eq cls

tests/neg/i14025.check

@@ -0,0 +1,8 @@
+-- Error: tests/neg/i14025.scala:1:88 ----------------------------------------------------------------------------------
+1 |val foo = summon[deriving.Mirror.Product { type MirroredType = [X] =>> [Y] =>> (X, Y) }] // error
+  |                                                                                        ^
+  |no given instance of type deriving.Mirror.Product{MirroredType[X] = [Y] =>> (X, Y)} was found for parameter x of method summon in object Predef
+-- Error: tests/neg/i14025.scala:2:90 ----------------------------------------------------------------------------------
+2 |val bar = summon[deriving.Mirror.Sum { type MirroredType = [X] =>> [Y] =>> List[(X, Y)] }] // error
+  |                                                                                          ^
+  |no given instance of type deriving.Mirror.Sum{MirroredType[X] = [Y] =>> List[(X, Y)]} was found for parameter x of method summon in object Predef

tests/neg/i14025.scala

@@ -0,0 +1,2 @@
+val foo = summon[deriving.Mirror.Product { type MirroredType = [X] =>> [Y] =>> (X, Y) }] // error
+val bar = summon[deriving.Mirror.Sum { type MirroredType = [X] =>> [Y] =>> List[(X, Y)] }] // error