1 files changed, 29 insertions, 0 deletions
diff --git a/lib/dialyzer/test/small_SUITE_data/undefined.erl b/lib/dialyzer/test/small_SUITE_data/undefined.erl
new file mode 100644
index 0000000000..8549f2e161
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+++ b/lib/dialyzer/test/small_SUITE_data/undefined.erl
@@ -0,0 +1,29 @@
+-module(undefined).
+
+-export([t/0]).
+
+%% As of OTP 19.0 'undefined' is no longer added to fields with a type
+%% declaration but without an initializer. The pretty printing of
+%% records (erl_types:t_to_string()) is updated to reflect this: if a
+%% field is of type 'undefined', it is output if 'undefined' is not in
+%% the declared type of the field. (It used to be the case that the
+%% singleton type 'undefined' was never output.)
+%%
+%% One consequence is shown by the example below: the warning about
+%% the record construction violating the the declared type shows
+%% #r{..., d::'undefined', ...} which is meant to be of help to the
+%% user, who could otherwise get confused the first time (s)he gets
+%% confronted by the warning.
+
+-record(r,
+        {
+          a = {fi},
+          b = {a,b} :: list(),                  % violation
+          c = {a,b} :: list(),
+          d :: list(),                          % violation
+          e = [] :: list(),
+          f = undefined :: list()               % violation
+        }).
+
+t() ->
+    #r{c = []}.