Fix a crash in race condition detection

Analysis is not always able to find the variable labels and names for any kind
of arguments passed to the ets module functions.

3 files changed, 25 insertions, 1 deletions

diff --git a/lib/dialyzer/src/dialyzer_races.erl b/lib/dialyzer/src/dialyzer_races.erl
index cdb9f25999..2aa8343bce 100644
--- a/lib/dialyzer/src/dialyzer_races.erl
+++ b/lib/dialyzer/src/dialyzer_races.erl
@@ -1758,7 +1758,10 @@ compare_var_list(Var, VarList, RaceVarMap) ->
 
 ets_list_args(MaybeList) ->
   case is_list(MaybeList) of
-    true -> [ets_tuple_args(T) || T <- MaybeList];
+    true ->
+      try [ets_tuple_args(T) || T <- MaybeList]
+      catch _:_ -> [?no_label]
+      end;
     false -> [ets_tuple_args(MaybeList)]
  end.
 
diff --git a/lib/dialyzer/test/race_SUITE_data/results/ets_insert_args10 b/lib/dialyzer/test/race_SUITE_data/results/ets_insert_args10
new file mode 100644
index 0000000000..c3c9b12bdd
--- /dev/null
+++ b/lib/dialyzer/test/race_SUITE_data/results/ets_insert_args10
@@ -0,0 +1,2 @@
+
+ets_insert_args10.erl:9: The call ets:insert(T::'foo',[{'counter',number()},...]) might have an unintended effect due to a possible race condition caused by its combination with the ets:lookup(T::'foo','counter') call in ets_insert_args10.erl on line 8
diff --git a/lib/dialyzer/test/race_SUITE_data/src/ets_insert_args10.erl b/lib/dialyzer/test/race_SUITE_data/src/ets_insert_args10.erl
new file mode 100644
index 0000000000..c897a34af0
--- /dev/null
+++ b/lib/dialyzer/test/race_SUITE_data/src/ets_insert_args10.erl
@@ -0,0 +1,19 @@
+%% This tests the presence of possible races due to an ets:lookup/ets:insert
+%% combination. It takes into account the argument types of the calls.
+
+-module(ets_insert_args10).
+-export([start/0]).
+
+start() ->
+  F = fun(T) -> [{_, N}] = ets:lookup(T, counter),
+               ets:insert(T, [{counter, N+1}])
+      end,
+  io:format("Created ~w\n", [ets:new(foo, [named_table, public])]),
+  A = {counter, 0},
+  B = [],
+  ets:insert(foo, [A|B]),
+  io:format("Inserted ~w\n", [{counter, 0}]),
+  F(foo),
+  io:format("Update complete\n", []),
+  ObjectList = ets:lookup(foo, counter),
+  io:format("Counter: ~w\n", [ObjectList]).