Convert to binary while still on client

lib/logger/lib/logger.ex

@@ -476,9 +476,16 @@ defmodule Logger do
           level: min_level, utc_log: utc_log?} = Logger.Config.__data__
 
         if compare_levels(level, min_level) != :lt do
+          truncated = truncate(chardata_or_fn, truncate)
           metadata = [pid: self()] ++ Keyword.merge(pdict, metadata)
-          tuple = {Logger, truncate(chardata_or_fn, truncate),
-                   Logger.Utils.timestamp(utc_log?), metadata}
+          message =
+            case :unicode.characters_to_binary(truncated) do
+              {_, good, bad} -> [good | Logger.Formatter.prune(bad)]
+              good -> good
+            end
+
+          tuple = {Logger, message, Logger.Utils.timestamp(utc_log?), metadata}
+
           try do
             notify(mode, {level, Process.group_leader(), tuple})
             :ok

lib/logger/lib/logger/backends/console.ex

@@ -76,14 +76,7 @@ defmodule Logger.Backends.Console do
     output =
       format_event(level, msg, ts, md, state)
       |> color_event(level, colors)
-    case :unicode.characters_to_binary(output) do
-      {:incomplete, good, bad} ->
-        send(device, {:io_request, self(), self(), {:put_chars, :unicode, [good | Logger.Formatter.prune(bad)]}})
-      {:error, good, bad} ->
-        send(device, {:io_request, self(), self(), {:put_chars, :unicode, [good | Logger.Formatter.prune(bad)]}})
-      good ->
-        send(device, {:io_request, self(), self(), {:put_chars, :unicode, good}})
-    end
+    send(device, {:io_request, self(), self(), {:put_chars, :unicode, output}})
   end
 
   defp format_event(level, msg, ts, md, %{format: format, metadata: keys}) do

lib/logger/test/logger_test.exs

@@ -288,6 +288,12 @@ defmodule LoggerTest do
     end
   end
 
+  test "log/2 prunes bad unicode chars" do
+    assert capture_log(fn ->
+      assert Logger.log(:debug, "he" <> <<185>> <> "lo") == :ok
+    end) =~ "he�lo"
+  end
+
   test "log/2 relies on sync_threshold" do
     Logger.remove_backend(:console)
     Logger.configure(sync_threshold: 0)