if a provider of the same namespace and name already exists, skip adding new provider

2 files changed, 19 insertions, 1 deletions

diff --git a/src/rebar.app.src b/src/rebar.app.src
index 67973eb..58fee02 100644
--- a/src/rebar.app.src
+++ b/src/rebar.app.src
@@ -27,6 +27,7 @@
                   certifi,
                   cth_readable,
                   relx,
+                  cf,
                   inets,
                   eunit_formatters]},
   {env, [
diff --git a/src/rebar_state.erl b/src/rebar_state.erl
index 176a80b..0c07b2a 100644
--- a/src/rebar_state.erl
+++ b/src/rebar_state.erl
@@ -370,7 +370,24 @@ providers(State, NewProviders) ->
 
 -spec add_provider(t(), providers:t()) -> t().
 add_provider(State=#state_t{providers=Providers}, Provider) ->
-    State#state_t{providers=[Provider | Providers]}.
+    Name = providers:impl(Provider),
+    Namespace = providers:namespace(Provider),
+    Module = providers:module(Provider),
+    case lists:any(fun(P) ->
+                           case {providers:impl(P), providers:namespace(P)} of
+                               {Name, Namespace} ->
+                                   ?DEBUG("Not adding provider ~p ~p from module ~p because it already exists from module ~p",
+                                          [Namespace, Name, providers:module(P), Module]),
+                                   true;
+                               _ ->
+                                   false
+                           end
+                   end, Providers) of
+        true ->
+            State;
+        false ->
+            State#state_t{providers=[Provider | Providers]}
+    end.
 
 create_logic_providers(ProviderModules, State0) ->
     try