qlc: Future-proof exception handling code

In the future, erlang:get_stacktrace/0 will probably only work
inside a the 'catch' block of a 'try' expression.

Future-proof the code by rewriting the old-style catch to
a try...catch.

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/stdlib/src/qlc.erl b/lib/stdlib/src/qlc.erl
index 20aaa2638c..535ca57a6b 100644
--- a/lib/stdlib/src/qlc.erl
+++ b/lib/stdlib/src/qlc.erl
@@ -1392,8 +1392,10 @@ next_loop(Pid, L, N) when N =/= 0 ->
         {caught, throw, Error, [?THROWN_ERROR | _]} ->
             Error;
         {caught, Class, Reason, Stacktrace} ->
-            _ = (catch erlang:error(foo)),
-            erlang:raise(Class, Reason, Stacktrace ++ erlang:get_stacktrace());
+            CurrentStacktrace = try erlang:error(foo)
+                                catch error:_ -> erlang:get_stacktrace()
+                                end,
+            erlang:raise(Class, Reason, Stacktrace ++ CurrentStacktrace);
         error ->
             erlang:error({qlc_cursor_pid_no_longer_exists, Pid})
     end;