The offending text in [1] is
..., which is defined in the functions complex_in() and complex_out() functions in Section 36.13.
One of the "functions" should go. Patch attached.
Yours,
Laurenz Albe
[1]: https://www.postgresql.org/docs/current/ecpg-variables.html#ECPG-VARIABLES-NONPRIMITIVE-SQL-USER-DEFINED-BASE-TYPES