From 6f73187d880262bce4dc787033d733df5ca0d767 Mon Sep 17 00:00:00 2001
From: v0idpwn <v0idpwn@gmail.com>
Date: Sun, 20 Oct 2024 17:14:25 -0300
Subject: [PATCH] Keep maps (actually, structs) for oneof

---
 lib/protobuf/encoder.ex        | 13 ++++++-------
 test/protobuf/encoder_test.exs | 11 +++++++++++
 test/support/test_msg.ex       |  2 ++
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/lib/protobuf/encoder.ex b/lib/protobuf/encoder.ex
index 69921269..6db7acce 100644
--- a/lib/protobuf/encoder.ex
+++ b/lib/protobuf/encoder.ex
@@ -73,19 +73,18 @@ defmodule Protobuf.Encoder do
           "Got error when encoding #{inspect(struct.__struct__)}##{prop.name_atom}: #{Exception.format(:error, error)}"
   end
 
+  defp skip_field?(_syntax, val, %FieldProps{oneof: oneof}) when not is_nil(oneof), do: is_nil(val)
   defp skip_field?(_syntax, [], _prop), do: true
   defp skip_field?(_syntax, val, _prop) when is_map(val), do: map_size(val) == 0
   defp skip_field?(:proto2, nil, %FieldProps{optional?: optional?}), do: optional?
   defp skip_field?(:proto2, value, %FieldProps{default: value, oneof: nil}), do: true
 
-  defp skip_field?(:proto3, val, %FieldProps{proto3_optional?: true}),
-    do: is_nil(val)
-
+  defp skip_field?(:proto3, val, %FieldProps{proto3_optional?: true}), do: is_nil(val)
   defp skip_field?(:proto3, nil, _prop), do: true
-  defp skip_field?(:proto3, 0, %FieldProps{oneof: nil}), do: true
-  defp skip_field?(:proto3, +0.0, %FieldProps{oneof: nil}), do: true
-  defp skip_field?(:proto3, "", %FieldProps{oneof: nil}), do: true
-  defp skip_field?(:proto3, false, %FieldProps{oneof: nil}), do: true
+  defp skip_field?(:proto3, 0, _prop), do: true
+  defp skip_field?(:proto3, +0.0, _prop), do: true
+  defp skip_field?(:proto3, "", _prop), do: true
+  defp skip_field?(:proto3, false, _prop), do: true
   defp skip_field?(_syntax, _val, _prop), do: false
 
   defp encode_field(
diff --git a/test/protobuf/encoder_test.exs b/test/protobuf/encoder_test.exs
index 12a9f32b..af486358 100644
--- a/test/protobuf/encoder_test.exs
+++ b/test/protobuf/encoder_test.exs
@@ -146,6 +146,10 @@ defmodule Protobuf.EncoderTest do
     msg = %TestMsg.Oneof{first: {:e, :UNKNOWN}}
     assert Encoder.encode(msg) == <<48, 0>>
     assert TestMsg.Oneof.decode(<<48, 0>>) == msg
+    # map
+    msg = %TestMsg.Oneof{first: {:f, %{}}}
+    assert Encoder.encode(msg) == <<58, 0>>
+    assert TestMsg.Oneof.decode(<<58, 0>>) == %TestMsg.Oneof{first: {:f, %TestMsg.Foo.Bar{}}}
 
     # proto3
     # int and string
@@ -159,6 +163,13 @@ defmodule Protobuf.EncoderTest do
     msg = %TestMsg.OneofProto3{first: {:e, :UNKNOWN}}
     assert Encoder.encode(msg) == <<48, 0>>
     assert TestMsg.OneofProto3.decode(<<48, 0>>) == msg
+    # map
+    msg = %TestMsg.OneofProto3{first: {:f, %{}}}
+    assert Encoder.encode(msg) == <<58, 0>>
+
+    assert TestMsg.OneofProto3.decode(<<58, 0>>) == %TestMsg.OneofProto3{
+             first: {:f, %TestMsg.Foo.Bar{}}
+           }
   end
 
   test "encodes proto3 optional fields zero values" do
diff --git a/test/support/test_msg.ex b/test/support/test_msg.ex
index 0da209c4..5403833c 100644
--- a/test/support/test_msg.ex
+++ b/test/support/test_msg.ex
@@ -113,6 +113,7 @@ defmodule TestMsg do
     field :c, 3, optional: true, type: :int32, oneof: 1
     field :d, 4, optional: true, type: :string, oneof: 1
     field :e, 6, optional: true, type: EnumFoo, enum: true, default: :A, oneof: 0
+    field :f, 7, optional: true, type: Foo.Bar, oneof: 0
     field :other, 5, optional: true, type: :string
   end
 
@@ -127,6 +128,7 @@ defmodule TestMsg do
     field :c, 3, optional: true, type: :int32, oneof: 1
     field :d, 4, optional: true, type: :string, oneof: 1
     field :e, 6, type: EnumFoo, enum: true, oneof: 0
+    field :f, 7, optional: true, type: Foo.Bar, oneof: 0
     field :other, 5, optional: true, type: :string
   end