Implement opts umerge deduplication

2 files changed, 14 insertions, 2 deletions

diff --git a/src/rebar_state.erl b/src/rebar_state.erl
index 22e5497..f73370b 100644
--- a/src/rebar_state.erl
+++ b/src/rebar_state.erl
@@ -231,7 +231,6 @@ do_deduplicate([Head | Rest], Acc) ->
 
 merge_opts(Profile, NewOpts, OldOpts) ->
     Opts = merge_opts(NewOpts, OldOpts),
-
     case dict:find(deps, NewOpts) of
         {ok, Value} ->
             dict:store({deps, Profile}, Value, Opts);
diff --git a/src/rebar_utils.erl b/src/rebar_utils.erl
index bc2e4ac..76be9a8 100644
--- a/src/rebar_utils.erl
+++ b/src/rebar_utils.erl
@@ -257,7 +257,20 @@ tup_sort(List) ->
 tup_umerge([], Olds) ->
     Olds;
 tup_umerge([New|News], Olds) ->
-    lists:reverse(umerge(News, Olds, [], New)).
+    reverse_deduplicate( umerge(News, Olds, [], New) ).
+
+reverse_deduplicate(List) ->
+    lists:reverse( do_deduplicate(lists:reverse(List), []) ).
+
+do_deduplicate([], Acc) ->
+    Acc;
+do_deduplicate([Value | Rest], Acc) ->
+    case lists:member(Value, Acc) of
+        true ->
+            do_deduplicate(Rest, Acc);
+        false ->
+            do_deduplicate(Rest, [Value | Acc])
+    end.
 
 %% This is equivalent to umerge2_2 in the stdlib, except we use the expanded
 %% value/key only to compare