Fix [C#] Object API - Invalid Property Name used in UnPackTo for unio… (#7751)

* Fix [C#] Object API - Invalid Property Name used in UnPackTo for union fieldhttps://github.com//issues/7750, also fixes invalid Code generated in WriteJson for Unions named Value.

* Test added: new schema union_value_collision.fbs with a Union named Value and a union field named value. The generated C# code now compiles when NetTest.bat. The Code generated with an older flatc.exe didn't compile because of a mismatch of the property name (Value vs. Value_).

* branch was not up-to-date with master

* BASE_OPTS + CPP_OPTS removed and union_value_collision_generated.h deleted

Co-authored-by: Derek Bailey <[email protected]>

Author: stefan301

scripts/generate_code.py

@@ -407,6 +407,13 @@ def glob(path, pattern):
 
 flatc(["--csharp", "--gen-object-api"], schema=type_field_collsion_schema)
 
+# Union / value collision
+flatc(
+    CS_OPTS + ["--gen-object-api", "--gen-onefile"],
+    prefix="union_value_collsion",
+    schema="union_value_collision.fbs"
+)
+
 # Generate string/vector default code for tests
 flatc(RUST_OPTS, prefix="more_defaults", schema="more_defaults.fbs")
 

src/idl_gen_csharp.cpp

@@ -1525,7 +1525,7 @@ class CSharpGenerator : public BaseGenerator {
               " _o, "
               "Newtonsoft.Json.JsonSerializer serializer) {\n";
       code += "    if (_o == null) return;\n";
-      code += "    serializer.Serialize(writer, _o.Value);\n";
+      code += "    serializer.Serialize(writer, _o." + class_member  + ");\n";
       code += "  }\n";
       code +=
           "  public override object ReadJson(Newtonsoft.Json.JsonReader "
@@ -1562,8 +1562,8 @@ class CSharpGenerator : public BaseGenerator {
           code += "      default: break;\n";
         } else {
           auto type_name = GenTypeGet_ObjectAPI(ev.union_type, opts);
-          code += "      case " + Name(enum_def) + "." + Name(ev) +
-                  ": _o.Value = serializer.Deserialize<" + type_name +
+          code += "      case " + Name(enum_def) + "." + Name(ev) + ": _o." +
+                  class_member + " = serializer.Deserialize<" + type_name +
                   ">(reader); break;\n";
         }
       }
@@ -1586,7 +1586,7 @@ class CSharpGenerator : public BaseGenerator {
     auto &code = *code_ptr;
     std::string varialbe_name = "_o." + camel_name;
     std::string class_member = "Value";
-    if (class_member == camel_name) class_member += "_";
+    if (class_member == enum_def.name) class_member += "_";
     std::string type_suffix = "";
     std::string func_suffix = "()";
     std::string indent = "    ";

tests/FlatBuffers.Test/FlatBuffers.Core.Test.csproj

@@ -169,6 +169,9 @@
     <Compile Include="..\nested_namespace_test\nested_namespace_test3_generated.cs">
       <Link>nested_namespace_test\nested_namespace_test3_generated.cs</Link>
     </Compile>
+    <Compile Include="..\union_value_collsion\union_value_collision_generated.cs">
+      <Link>union_value_collsion\union_value_collision_generated.cs</Link>
+    </Compile>
   </ItemGroup>
 
   <ItemGroup>

tests/union_value_collision.fbs

@@ -0,0 +1,17 @@
+namespace union_value_collsion;
+
+table IntValue {
+	value:int;
+}
+
+union Value { IntValue }
+
+union Other { IntValue }
+
+// This table tests collsions of Unions and fields named value.
+table Collision {
+  some_value : Value;
+  value : Other;
+}
+
+root_type Collision;