3 files changed, 65 insertions, 3 deletions

diff --git a/lib/stdlib/test/gen_fsm_SUITE.erl b/lib/stdlib/test/gen_fsm_SUITE.erl
index 41ee3246f5..a8264e5a84 100644
--- a/lib/stdlib/test/gen_fsm_SUITE.erl
+++ b/lib/stdlib/test/gen_fsm_SUITE.erl
@@ -124,8 +124,10 @@ start2(Config) when is_list(Config) ->
     {ok, Pid0} = gen_fsm:start(gen_fsm_SUITE, [], []),
     ok = do_func_test(Pid0),
     ok = do_sync_func_test(Pid0),
+    MRef = monitor(process,Pid0),
     shutdown_stopped =
 	gen_fsm:sync_send_all_state_event(Pid0, stop_shutdown),
+    receive {'DOWN',MRef,_,_,shutdown} -> ok end,
     {'EXIT', {noproc,_}} =
 	(catch gen_fsm:sync_send_event(Pid0, hej)),
 
diff --git a/lib/stdlib/test/lists_SUITE.erl b/lib/stdlib/test/lists_SUITE.erl
index 837ab4e97e..984b51e7ae 100644
--- a/lib/stdlib/test/lists_SUITE.erl
+++ b/lib/stdlib/test/lists_SUITE.erl
@@ -2597,6 +2597,20 @@ subtract(Config) when is_list(Config) ->
     {'EXIT',_} = (catch sub([a|b], [])),
     {'EXIT',_} = (catch sub([a|b], [a])),
 
+    %% Trapping, both crashing and otherwise.
+    [sub_trapping(N) || N <- lists:seq(0, 18)],
+
+    %% The current implementation chooses which algorithm to use based on
+    %% certain thresholds, and we need proper coverage for all corner cases.
+    [sub_thresholds(N) || N <- lists:seq(0, 32)],
+
+    %% Trapping, both crashing and otherwise.
+    [sub_trapping(N) || N <- lists:seq(0, 18)],
+
+    %% The current implementation chooses which algorithm to use based on
+    %% certain thresholds, and we need proper coverage for all corner cases.
+    [sub_thresholds(N) || N <- lists:seq(0, 32)],
+
     ok.
 
 sub_non_matching(A, B) ->
@@ -2606,6 +2620,41 @@ sub(A, B) ->
     Res = A -- B,
     Res = lists:subtract(A, B).
 
+sub_trapping(N) ->
+    List = lists:duplicate(N + (1 bsl N), gurka),
+    ImproperList = List ++ crash,
+
+    {'EXIT',_} = (catch sub_trapping_1(ImproperList, [])),
+    {'EXIT',_} = (catch sub_trapping_1(List, ImproperList)),
+
+    List = List -- lists:duplicate(N + (1 bsl N), gaffel),
+    ok = sub_trapping_1(List, []).
+
+sub_trapping_1([], _) -> ok;
+sub_trapping_1(L, R) -> sub_trapping_1(L -- R, [gurka | R]).
+
+sub_thresholds(N) ->
+    %% This needs to be long enough to cause trapping.
+    OtherLen = 1 bsl 18,
+    Other = lists:seq(0, OtherLen - 1),
+
+    Disjoint = lists:seq(-N, -1),
+    Subset = lists:seq(1, N),
+
+    %% LHS is disjoint from RHS, so all elements must be retained.
+    Disjoint = Disjoint -- Other,
+
+    %% LHS is covered by RHS, so all elements must be removed.
+    [] = Subset -- Other,
+
+    %% RHS is disjoint from LHS, so all elements must be retained.
+    Other = Other -- Disjoint,
+
+    %% RHS is covered by LHS, so N elements must be removed.
+    N = OtherLen - length(Other -- Subset),
+
+    ok.
+
 %% Test lists:droplast/1
 droplast(Config) when is_list(Config) ->
     [] = lists:droplast([x]),
diff --git a/lib/stdlib/test/sys_SUITE.erl b/lib/stdlib/test/sys_SUITE.erl
index 3278eb0eb0..fcc4419569 100644
--- a/lib/stdlib/test/sys_SUITE.erl
+++ b/lib/stdlib/test/sys_SUITE.erl
@@ -219,7 +219,7 @@ spec_proc(Mod) ->
 		       {Mod,system_get_state},{throw,fail}},_}} ->
 		 ok
 	 end,
-    ok = sys:terminate(Mod, normal),
+    ok = sync_terminate(Mod),
     {ok,_} = Mod:start_link(4),
     ok = case catch sys:replace_state(Mod, fun(_) -> {} end) of
 	     {} ->
@@ -228,7 +228,7 @@ spec_proc(Mod) ->
 		       {Mod,system_replace_state},{throw,fail}},_}} ->
 		 ok
 	 end,
-    ok = sys:terminate(Mod, normal),
+    ok = sync_terminate(Mod),
     {ok,_} = Mod:start_link(4),
     StateFun = fun(_) -> error(fail) end,
     ok = case catch sys:replace_state(Mod, StateFun) of
@@ -240,7 +240,18 @@ spec_proc(Mod) ->
 	     {'EXIT',{{callback_failed,StateFun,{error,fail}},_}} ->
 		 ok
 	 end,
-    ok = sys:terminate(Mod, normal).
+    ok = sync_terminate(Mod).
+
+sync_terminate(Mod) ->
+    P = whereis(Mod),
+    MRef = erlang:monitor(process,P),
+    ok = sys:terminate(Mod, normal),
+    receive
+        {'DOWN',MRef,_,_,normal} ->
+            ok
+    end,
+    undefined = whereis(Mod),
+    ok.
 
 %%%%%%%%%%%%%%%%%%%%
 %% Dummy server