Merge pull request #3723 from lexmag/dialyzer-trick

Make it clearer that unimplemented callbacks always stop

Author: fishcakez

lib/elixir/lib/gen_event.ex

@@ -341,9 +341,10 @@ defmodule GenEvent do
       @doc false
       def handle_call(msg, state) do
         # We do this to trick dialyzer to not complain about non-local returns.
-        case :random.uniform(1) do
-          1 -> exit({:bad_call, msg})
-          2 -> {:remove_handler, :ok}
+        reason = {:bad_call, msg}
+        case :erlang.phash2(1, 1) do
+          0 -> exit(reason)
+          1 -> {:remove_handler, reason}
         end
       end
 
@@ -376,7 +377,7 @@ defmodule GenEvent do
   section in the `GenServer` module docs.
 
   If the event manager is successfully created and initialized, the function
-  returns `{:ok, pid}`, where pid is the pid of the server. If a process with 
+  returns `{:ok, pid}`, where pid is the pid of the server. If a process with
   the specified server name already exists, the function returns
   `{:error, {:already_started, pid}}` with the pid of that process.
 

lib/elixir/lib/gen_event/stream.ex

@@ -22,15 +22,20 @@ defmodule GenEvent.Stream do
 
   @doc false
   def handle_event(event, _state) do
-    exit({:bad_event, event})
+    # We do this to trick dialyzer to not complain about non-local returns.
+    case :erlang.phash2(1, 1) do
+      0 -> exit({:bad_event, event})
+      1 -> :remove_handler
+    end
   end
 
   @doc false
   def handle_call(msg, _state) do
     # We do this to trick dialyzer to not complain about non-local returns.
-    case :random.uniform(1) do
-      1 -> exit({:bad_call, msg})
-      2 -> {:remove_handler, :ok}
+    reason = {:bad_call, msg}
+    case :erlang.phash2(1, 1) do
+      0 -> exit(reason)
+      1 -> {:remove_handler, reason}
     end
   end
 

lib/elixir/lib/gen_server.ex

@@ -409,9 +409,10 @@ defmodule GenServer do
       @doc false
       def handle_call(msg, _from, state) do
         # We do this to trick Dialyzer to not complain about non-local returns.
-        case :random.uniform(1) do
-          1 -> exit({:bad_call, msg})
-          2 -> {:noreply, state}
+        reason = {:bad_call, msg}
+        case :erlang.phash2(1, 1) do
+          0 -> exit(reason)
+          1 -> {:stop, reason, state}
         end
       end
 
@@ -423,9 +424,10 @@ defmodule GenServer do
       @doc false
       def handle_cast(msg, state) do
         # We do this to trick Dialyzer to not complain about non-local returns.
-        case :random.uniform(1) do
-          1 -> exit({:bad_cast, msg})
-          2 -> {:noreply, state}
+        reason = {:bad_cast, msg}
+        case :erlang.phash2(1, 1) do
+          0 -> exit(reason)
+          1 -> {:stop, reason, state}
         end
       end
 
@@ -474,7 +476,7 @@ defmodule GenServer do
   ## Return values
 
   If the server is successfully created and initialized, the function returns
-  `{:ok, pid}`, where pid is the pid of the server. If a process with the 
+  `{:ok, pid}`, where pid is the pid of the server. If a process with the
   specified server name already exists, the function returns
   `{:error, {:already_started, pid}}` with the pid of that process.