Fix header folding bug

A prepare_request callback from diameter can return a diameter_header
record with in order to set values in the header of an outgoing
request. The fault in diameter_lib:fold_tuple/3 caused encode of
the outgoing request to fail.

1 files changed, 8 insertions, 7 deletions

diff --git a/lib/diameter/src/app/diameter_lib.erl b/lib/diameter/src/app/diameter_lib.erl
index b5c0e1bf6a..46fd87c591 100644
--- a/lib/diameter/src/app/diameter_lib.erl
+++ b/lib/diameter/src/app/diameter_lib.erl
@@ -255,12 +255,13 @@ w(L) ->
 fold_tuple(_, T, undefined) ->
     T;
 
-fold_tuple(N, T0, T) ->
-    element(2, lists:foldl(fun(X, {M,_} = A) -> {M+1, ft(X, A)} end,
-                           {N, T0},
-                           lists:nthtail(N-1, tuple_to_list(T)))).
+fold_tuple(N, T0, T1) ->
+    {_, T} = lists:foldl(fun(V, {I,_} = IT) -> {I+1, ft(V, IT)} end,
+                         {N, T0},
+                         lists:nthtail(N-1, tuple_to_list(T1))),
+    T.
 
-ft(undefined, T) ->
+ft(undefined, {_, T}) ->
     T;
-ft(X, {N, T}) ->
-    setelement(N, T, X).
+ft(Value, {Idx, T}) ->
+    setelement(Idx, T, Value).