[erlang-questions] incomplete union checks in dialyzer

Tobias Lindahl <>
Thu Aug 30 14:41:19 CEST 2012

2012/8/30 Motiejus Jakštys <>

> On Thu, Aug 30, 2012 at 12:03 PM, Kostis Sagonas <>
> wrote:
> > On 08/30/2012 11:53 AM, Motiejus Jakštys wrote:
> >>
> >> I wonder how hard would this be to encapsulate and add to dialyzer as
> >> a run-time option?
> >
> >
> > Very simple, I guess.
> Thanks again. I will look into that.
I'm not sure that this is a good idea. This set limit is controlling the
size of the inferred types, basically telling Dialyzer when to abstract
some types (i.e., 15 separate atoms will be collapsed into atom()). This is
of course affecting the fix point behavior of the analysis, as Kostis says,
which is fine.

However, if the plt is built with one setting and the later analysis uses
another, I can imagine that you might end up in a situation where no fix
point can be found, yielding an infinite loop.

Making this into a run time option indicates that it is something you can
play around with in order to get better results. To some extent it is, but
since it can have pretty serious implications it might not be a good idea.

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