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%% Test case that results in a confusing warning -- created from a
%% very stripped down actual application. The second case clause of
%% test/1 cannot possibly match because all a-pairs match with the
%% first clause. Dialyzer complains that the second argument of the
%% second 2-tuple has type 'aaa' | 'bbb'. This is mucho confusing
%% since there is no 'a'-pair whose second element is 'aaa' | 'bbb'.
%% Pattern matching compilation is of course what's to blame here.
-module(confusing_warning).
-export([test/1]).
test(N) when is_integer(N) ->
case foo(N) of
{a, I} when is_integer(I) ->
I;
{a, {_, L}} -> % this clause cannot possibly match
L
end.
foo(1) -> {a, 42};
foo(2) -> {b, aaa}; % this is really unused
foo(3) -> {b, bbb}. % this is really unused
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