Fix Elixir 1.3 compiler warnings

lib/riffed/client.ex

@@ -114,16 +114,16 @@ defmodule Riffed.Client do
     |> Keyword.delete(:host)
     |> Keyword.delete(:retries)
 
-    if Module.get_attribute(env.module, :auto_import_structs) do
-      struct_module = quote do
+    struct_module = if Module.get_attribute(env.module, :auto_import_structs) do
+      quote do
         defmodule unquote(struct_module) do
           use Riffed.Struct, unquote(Meta.structs_to_keyword(thrift_metadata))
           unquote_splicing(Riffed.Callbacks.reconstitute(env.module))
           unquote_splicing(Riffed.Enumeration.reconstitute(env.module))
         end
       end
     else
-      struct_module = quote do
+      quote do
       end
     end
 

lib/riffed/macro_helpers.ex

@@ -15,7 +15,7 @@ defmodule Riffed.MacroHelpers do
     |> Enum.map(&build_arg_cast(function_name, struct_module, &1, overrides, cast_function))
   end
 
-  defp build_arg({index, _type}=arg) do
+  defp build_arg({index, _type}) do
     Macro.var(:"arg_#{abs(index)}", nil)
   end
 

lib/riffed/server.ex

@@ -180,8 +180,8 @@ defmodule Riffed.Server do
 
     structs_keyword = ThriftMeta.Meta.structs_to_keyword(thrift_meta)
 
-    if Module.get_attribute(env.module, :auto_import_structs)  do
-      struct_module = quote do
+    struct_module = if Module.get_attribute(env.module, :auto_import_structs)  do
+      quote do
         defmodule unquote(struct_module) do
           @build_cast_to_erlang true
           use Riffed.Struct, unquote(structs_keyword)
@@ -190,7 +190,7 @@ defmodule Riffed.Server do
         end
       end
     else
-      struct_module = quote do
+      quote do
       end
     end
 

lib/riffed/struct.ex

@@ -304,9 +304,10 @@ defmodule Riffed.Struct do
     callbacks = Riffed.Callbacks.build(env.module)
     enums = Riffed.Enumeration.build(env.module)
 
-    erlang_casts = []
-    if build_cast_to_erlang do
-      erlang_casts = Riffed.Enumeration.build_cast_return_value_to_erlang(env.module)
+    erlang_casts = if build_cast_to_erlang do
+      Riffed.Enumeration.build_cast_return_value_to_erlang(env.module)
+    else
+      []
     end
 
     quote do