Error: The abbreviation basic_block expands to type

< add : Type.texpr -> unit; add_terminator : Type.texpr -> unit;

copy : unit -> 'a; does_terminate : unit -> bool;

get_id : unit -> int; is_empty : unit -> bool;

merge : basic_block -> unit;

set_next : basic_block block_next -> unit; terminate : unit -> unit;

to_texpr : unit -> Type.texpr >

but is used with type

< is_empty : unit -> bool; to_expr : unit -> Type.texpr;

to_texpr : unit -> Type.texpr; .. >