module Foo = struct
    module M = struct end

    module type S = sig end

    type t =
      { a : (module S)
      ; b : (module S)
      }

    let _t = { a = (module M : S); b = (module M : S) }
  end
ocamlformat.exe: Cannot process "****.ml".
  Please report this bug at https://github.com/ocaml-ppx/ocamlformat/issues.
  BUG: unhandled exception. Use [--debug] for details.
EXIT STATUS 1