add oneof field for actually written fields

pb.c

@@ -1685,7 +1685,7 @@ static void lpb_usedechooks(lua_State *L, lpb_State *LS, const pb_Type *t) {
 static void lpb_pushtypetable(lua_State *L, lpb_State *LS, const pb_Type *t) {
     const pb_Field *f = NULL;
     int mode = LS->default_mode;
-    lua_createtable(L, 0, t->field_count - t->oneof_count);
+    lua_createtable(L, 0, t->field_count - t->oneof_field + t->oneof_count*2);
     switch (t->is_proto3 && mode == LPB_DEFDEF ? LPB_COPYDEF : mode) {
     case LPB_COPYDEF:
         while (pb_nextfield(t, &f))
@@ -1827,6 +1827,11 @@ static int lpbD_message(lpb_Env *e, const pb_Type *t) {
             lpbD_repeated(e, f, tag);
         else {
             lua_pushstring(L, (const char*)f->name);
+            if (f->oneof_idx) {
+                lua_pushstring(L, (const char*)pb_oneofname(t, f->oneof_idx));
+                lua_pushvalue(L, -2);
+                lua_rawset(L, -4);
+            }
             lpbD_field(e, f, tag);
             lua_rawset(L, -3);
         }

pb.h

@@ -338,6 +338,7 @@ struct pb_Type {
     pb_Table field_names;
     pb_Table oneof_index;
     unsigned oneof_count; /* extra field count from oneof entries */
+    unsigned oneof_field; /* extra field in oneof declarations */
     unsigned field_count : 28;
     unsigned is_enum   : 1;
     unsigned is_map    : 1;
@@ -1245,7 +1246,7 @@ PB_API void pb_deltype(pb_State *S, pb_Type *t) {
     pb_freetable(&t->field_tags);
     pb_freetable(&t->field_names);
     pb_freetable(&t->oneof_index);
-    t->oneof_count = 0, t->field_count = 0;
+    t->oneof_field = 0, t->field_count = 0;
     t->is_dead = 1;
     /*pb_delname(S, t->name); */
     /*pb_poolfree(&S->typepool, t); */
@@ -1630,7 +1631,7 @@ static int pbL_loadField(pb_State *S, pbL_FieldInfo *info, pb_Loader *L, pb_Type
     pbCE(f = pb_newfield(S, t, pb_newname(S, info->name, NULL), info->number));
     f->default_value = pb_newname(S, info->default_value, NULL);
     f->type      = ft;
-    if ((f->oneof_idx = info->oneof_index)) ++t->oneof_count;
+    if ((f->oneof_idx = info->oneof_index)) ++t->oneof_field;
     f->type_id   = info->type;
     f->repeated  = info->label == 3; /* repeated */
     f->packed    = info->packed >= 0 ? info->packed : L->is_proto3 && f->repeated;
@@ -1659,7 +1660,7 @@ static int pbL_loadType(pb_State *S, pbL_TypeInfo *info, pb_Loader *L) {
         pbC(pbL_loadEnum(S, &info->enum_type[i], L));
     for (i = 0, count = pbL_count(info->nested_type); i < count; ++i)
         pbC(pbL_loadType(S, &info->nested_type[i], L));
-    t->oneof_count -= pbL_count(info->oneof_decl);
+    t->oneof_count = pbL_count(info->oneof_decl);
     L->b.size = (unsigned)curr;
     return PB_OK;
 }

test.lua

@@ -11,6 +11,7 @@ local protoc = require "protoc"
 local eq       = lu.assertEquals
 local table_eq = lu.assertItemsEquals
 local fail     = lu.assertErrorMsgContains
+local is_true  = lu.assertIsTrue
 
 local types = 0
 for _ in pb.types() do
@@ -543,6 +544,9 @@ function _G.test_packed()
    fail("table expected at field 'packs', got boolean",
         function() pb.encode("TestPacked", { packs = true }) end)
 
+   local data = {packs = {}}
+   check_msg(".TestPacked", data, {})
+
    local hasEmpty
    for _, name in pb.types() do
       if name == "Empty" then
@@ -684,10 +688,10 @@ function _G.test_oneof()
        }
    } ]]
    check_msg("TestOneof", {})
-   check_msg("TestOneof", { m1 = {} })
-   check_msg("TestOneof", { m2 = {} })
-   check_msg("TestOneof", { m3 = { value = 0 } })
-   check_msg("TestOneof", { m3 = { value = 10 } })
+   check_msg("TestOneof", { m1 = {}, body_oneof = "m1" })
+   check_msg("TestOneof", { m2 = {}, body_oneof = "m2" })
+   check_msg("TestOneof", { m3 = { value = 0 }, body_oneof = "m3" })
+   check_msg("TestOneof", { m3 = { value = 10 }, body_oneof = "m3" })
    pb.clear "TestOneof"
 
    check_load [[
@@ -702,12 +706,17 @@ function _G.test_oneof()
       TestOneof msg = 1;
    }
    ]]
-   check_msg("TestOneof", { foo = 0 })
-   check_msg("TestOneof", { bar = "" })
-   check_msg("TestOneof", { foo = 0, bar = "" })
-   check_msg("Outter", { msg = { foo = 0 }})
-   check_msg("Outter", { msg = { bar = "" }})
-   check_msg("Outter", { msg = { foo = 0, bar = "" }})
+
+   check_msg("TestOneof", { foo = 0, body = "foo" })
+   check_msg("TestOneof", { bar = "", body = "bar" })
+   local chunk = pb.encode("TestOneof", { foo = 0, bar = "" })
+   local data = pb.decode("TestOneof", chunk)
+   is_true(data.body == "foo" or data.body == "bar")
+   check_msg("Outter", { msg = { foo = 0, body = "foo" }})
+   check_msg("Outter", { msg = { bar = "", body = "bar" }})
+   local chunk = pb.encode("Outter", {msg = { foo = 0, bar = "" }})
+   local data = pb.decode("Outter", chunk)
+   is_true(data.msg.body == "foo" or data.msg.body == "bar")
    pb.clear "TestOneof"
    pb.clear "Outter"
 
@@ -720,12 +729,12 @@ function _G.test_oneof()
        }
    } ]]
 
-   check_msg("TestOneof", { name = "foo" })
-   check_msg("TestOneof", { value = 0 })
-   check_msg("TestOneof", { name = "foo", value = 0 })
+   check_msg("TestOneof", { name = "foo", test_oneof = "name" })
+   check_msg("TestOneof", { value = 0, test_oneof = "value" })
+   local chunk = pb.encode("TestOneof", { name = "foo", value = 0 })
+   local data = pb.decode("TestOneof", chunk)
+   is_true(data.test_oneof == "name" or data.test_oneof == "value")
 
-   local data = { name = "foo", value = 5 }
-   check_msg("TestOneof", data)
    eq(pb.field("TestOneof", "name"), "name")
    pb.clear("TestOneof", "name")
    eq(pb.field("TestOneof", "name"), nil)