{motive : Lean.IR.LogEntry → Sort u} →
  (t : Lean.IR.LogEntry) →
    ((cls : Lean.Name) → (decls : Array Lean.IR.Decl) → motive (Lean.IR.LogEntry.step cls decls)) →
      ((msg : Std.Format) → motive (Lean.IR.LogEntry.message msg)) → motive t