Merge branch 'hasse/dialyzer/stacktrace_variable/OTP-14862'

* hasse/dialyzer/stacktrace_variable/OTP-14862:
  dialyzer: Assign a type to the  primop build_stacktrace

4 files changed, 84 insertions, 2 deletions

diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl
index 384912f983..32f58efc75 100644
--- a/lib/dialyzer/src/dialyzer_dataflow.erl
+++ b/lib/dialyzer/src/dialyzer_dataflow.erl
@@ -299,7 +299,7 @@ traverse(Tree, Map, State) ->
 	  match_fail -> t_none();
 	  raise -> t_none();
 	  bs_init_writable -> t_from_term(<<>>);
-          build_stacktrace -> t_list();
+          build_stacktrace -> erl_bif_types:type(erlang, build_stacktrace, 0);
 	  Other -> erlang:error({'Unsupported primop', Other})
 	end,
       {State, Map, Type};
diff --git a/lib/dialyzer/src/dialyzer_typesig.erl b/lib/dialyzer/src/dialyzer_typesig.erl
index b1f6a54503..6776f87b66 100644
--- a/lib/dialyzer/src/dialyzer_typesig.erl
+++ b/lib/dialyzer/src/dialyzer_typesig.erl
@@ -418,7 +418,11 @@ traverse(Tree, DefinedVars, State) ->
 	match_fail -> throw(error);
 	raise -> throw(error);
 	bs_init_writable -> {State, t_from_term(<<>>)};
-	build_stacktrace -> {State, t_list()};
+	build_stacktrace ->
+          V = mk_var(Tree),
+          Type = erl_bif_types:type(erlang, build_stacktrace, 0),
+          State1 = state__store_conj(V, sub, Type, State),
+          {State1, V};
 	Other -> erlang:error({'Unsupported primop', Other})
       end;
     'receive' ->
diff --git a/lib/dialyzer/test/small_SUITE_data/results/stacktrace b/lib/dialyzer/test/small_SUITE_data/results/stacktrace
new file mode 100644
index 0000000000..fd60881953
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/results/stacktrace
@@ -0,0 +1,5 @@
+
+stacktrace.erl:11: The pattern {'a', 'b'} can never match the type [{atom(),atom(),[any()] | byte(),[{'file',string()} | {'line',pos_integer()}]}]
+stacktrace.erl:19: The pattern ['a', 'b'] can never match the type [{atom(),atom(),[any()] | byte(),[{'file',string()} | {'line',pos_integer()}]}]
+stacktrace.erl:44: The pattern {'a', 'b'} can never match the type [{atom(),atom(),[any()] | byte(),[{'file',string()} | {'line',pos_integer()}]}]
+stacktrace.erl:53: The pattern ['a', 'b'] can never match the type [{atom(),atom(),[any()] | byte(),[{'file',string()} | {'line',pos_integer()}]}]
diff --git a/lib/dialyzer/test/small_SUITE_data/src/stacktrace.erl b/lib/dialyzer/test/small_SUITE_data/src/stacktrace.erl
new file mode 100644
index 0000000000..de79e710e9
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/src/stacktrace.erl
@@ -0,0 +1,73 @@
+-module(stacktrace).
+
+%% Check the stacktrace variable introduced in Erlang/OTP 21.0
+
+-export([t1/0, t2/0, t3/0, t4/0, s1/0, s2/0, s3/0, s4/0]).
+
+t1() ->
+    try foo:bar()
+    catch
+        E:P:S ->
+            {a,b} = S, % can never match
+            {E, P}
+    end.
+
+t2() ->
+    try foo:bar()
+    catch
+        E:P:S ->
+            [a,b] = S, % can never match
+            {E, P}
+    end.
+
+t3() ->
+    try foo:bar()
+    catch
+        E:P:S ->
+            [{m,f,[],[]}] = S,
+            {E, P}
+    end.
+
+t4() ->
+    try foo:bar()
+    catch
+        E:P:S ->
+            [{m,f,1,[{file,"tjo"},{line,95}]}] = S,
+            {E, P}
+    end.
+
+s1() ->
+    try foo:bar()
+    catch
+        E:P ->
+            S = erlang:get_stacktrace(),
+            {a,b} = S, % can never match
+            {E, P}
+    end.
+
+s2() ->
+    try foo:bar()
+    catch
+        E:P ->
+            S = erlang:get_stacktrace(),
+            [a,b] = S, % can never match
+            {E, P}
+    end.
+
+s3() ->
+    try foo:bar()
+    catch
+        E:P ->
+            S = erlang:get_stacktrace(),
+            [{m,f,[],[]}] = S,
+            {E, P}
+    end.
+
+s4() ->
+    try foo:bar()
+    catch
+        E:P ->
+            S = erlang:get_stacktrace(),
+            [{m,f,1,[{file,"tjo"},{line,95}]}] = S,
+            {E, P}
+    end.