[erlang-questions] Dialyzer Error: "Analysis failed with error"

Kostis Sagonas kostis@REDACTED
Sat Jun 25 09:32:15 CEST 2011

David Mercer wrote:
> Inspired by 
> http://www.erlang-factory.com/upload/presentations/347/Kostis.pdf, I 
> decided to give Dialyzer a go.  The first file I tried it on, however, 
> failed with a rather unhelpful error.  After trimming a few thousand 
> lines, I’ve got it down to the following minimal case:
> -module(dialyzer_test).
> -export([test/1]).
> -record(rec1, {f1}).
> -record(rec2, {f2}).
> -type rec1(T) :: #rec1{f1 :: T}.
> -type rec2(T) :: #rec2{f2 :: T}.
> -spec test(rec2(rec1(A))) -> A.
> test(#rec2{f2 = #rec1{f1 = X}}) -> X.
> The Dialyzer error is:
> dialyzer: Analysis failed with error: Illegal declaration of #rec2{f2} 
> Can anyone explain to me what’s wrong with my types and spec?  Please 
> advise.  Thank-you.

In principle there is nothing wrong with your types and specs. It seems 
you have hit a limitation (bug?) which makes parametric types involving 
records not handled properly by Erlang/OTP. (Record expressions are 
nasty, because they are handled by the preprocessor.) I'll try to see 
what can be done about it for R14B04.

In the meantime, you can bypass this error by declaring the type you 
want as follows:

   -type rec2rec1(T) :: {rec2, rec1(T)}.

   -spec test(rec2rec1(A)) -> A.

Far from ideal, I know...

Thanks for the minimal test case!


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