Marker trait field inconsistent naming

[maximebuyse]

trait T2 {}

impl<U> T2 for U  {}

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This code gets translated as:

class t_T2 (v_Self: Type0) = {
  __marker_trait_t_T2:Prims.unit
}

[@@ FStar.Tactics.Typeclasses.tcinstance]
let impl (#v_U: Type0) : t_T2 v_U =
  { __marker_trait = () }

There is an inconsistency between __marker_trait_t_T2 in the type class definition and __marker_trait in the impl.