Dialyzer: Cons will produce an improper list since its 2nd argument is none()

[Jesper Eskilson]

Hi,

When dialyzer analyzes this program:


-module(foo).
-export([main/0]).
-record(foo, {x :: integer()}).
main() ->
  [ #foo{x = 0},
    #foo{x = false} ].


it says:

foo.erl:7: Function main/0 has no local return
foo.erl:8: Cons will produce an improper list since its 2nd argument is
          none()
foo.erl:9: Record construction
          #foo{x :: false} violates the declared type of field x ::
          integer()


It seems like dialyzer assumes that any cons with second argument not being
a list will produce an improper list, but shouldn't it treat "none()"
differently?

Is this a bug in dialyzer, or a feature whose usefulness I am unable to
grasp?

-- 

*Jesper Eskilson*
Senior Software Engineer
Kred Core
+46-72-855-8421

Klarna Bank AB (publ)
Sveavägen 46, 111 34 Stockholm
Tel: +46 8 120 120 00 <+46812012000>
Reg no: 556737-0431
klarna.com
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