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Given a kind signature type T :: forall k. k -> forall k. k -> blah data T a b = ... where those k's have the same unique (which is possible; see #19093) we were giving the tyConBinders in tycon T the same unique, which caused chaos. Fix is simple: ensure uniqueness when decomposing the kind signature. See GHC.Tc.Gen.HsType.zipBinders
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