[erlang-bugs] Problem with nested opaque types

Kostis Sagonas <>
Thu Oct 18 23:07:30 CEST 2012

On 10/18/2012 07:39 PM, Jesper Larsson wrote:
> Hi,
> This seems related to
> http://erlang.org/pipermail/erlang-bugs/2010-July/001904.html which is
> allegedly fixed, but the problem described below still exists. I have
> Erlang R15B02 and Dialyzer reports version v2.5.2. (I couldn't find how
> to map these numbers to each other.)
> I boiled it down to this:  ...

Hi Jesper,

Thanks for the bug report.

Yes, I would call this a bug. We are aware that there are still issues 
with opaque datatypes -- note that they are not documented and this is 
for a reason. But we will investigate this nonetheless.


PS. Another way of shutting off the warnings (though I am not sure why) 
is to define the spec in module exporter as:

   -spec traverser(exporter:tree()) -> exporter:trav().

But I am not suggesting this as a long term "solution".

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