Singletons/T342.hs:(0,0)-(0,0): Splicing declarations
    do synName <- newName "MyId"
       a <- newName "a"
       let dsyn = DTySynD synName [DPlainTV a ()] (DVarT a)
           syn = decToTH dsyn
       defuns <- withLocalDeclarations [syn] $ genDefunSymbols [synName]
       pure $ syn : defuns
  ======>
    type MyId a = a
    data MyIdSym0 a0123456789876543210
      where
        MyIdSym0KindInference :: SameKind (Apply MyIdSym0 arg) (MyIdSym1 arg) =>
                                 MyIdSym0 a0123456789876543210
    type instance Apply MyIdSym0 a0123456789876543210 = MyId a0123456789876543210
    instance SuppressUnusedWarnings MyIdSym0 where
      suppressUnusedWarnings = snd ((,) MyIdSym0KindInference ())
    type family MyIdSym1 a0123456789876543210 where
      MyIdSym1 a0123456789876543210 = MyId a0123456789876543210