C#: Added <autogenerated> in cs generator file header comment (#4291)

* Added <autogenerated> in cs generator file header comment
#4287

* CS: Added xml-correct file header comment including "<auto-generated>...</auto-generated>"
code_generators.cpp: FlatBuffersGeneratedWarning() function replaced by compile time constant "GeneratedWarning"
 also removed extra newlines at end of GeneratedWarning to be able to generate a xml well formed file comment for cs files
#4291

* code_generators: Changed static string GeneratedWarning back to function FlatBuffersGeneratedWarning()
#4291

* Added modified Unit-Test files
#4291

* idl_gen_general: Add autogenerated only in C# code
#4291

src/code_generators.cpp

@@ -68,7 +68,7 @@ void CodeWriter::operator+=(std::string text) {
 
 const char *BaseGenerator::FlatBuffersGeneratedWarning() {
   return "automatically generated by the FlatBuffers compiler,"
-         " do not modify\n\n";
+         " do not modify";
 }
 
 std::string BaseGenerator::NamespaceDir(const Parser &parser,

src/idl_gen_cpp.cpp

@@ -88,7 +88,7 @@ class CppGenerator : public BaseGenerator {
   // structs, and tables) and output them to a single file.
   bool generate() {
     code_.Clear();
-    code_ += "// " + std::string(FlatBuffersGeneratedWarning());
+    code_ += "// " + std::string(FlatBuffersGeneratedWarning()) + "\n\n";
 
     const auto include_guard = GenIncludeGuard();
     code_ += "#ifndef " + include_guard;

src/idl_gen_general.cpp

@@ -20,7 +20,6 @@
 #include "flatbuffers/idl.h"
 #include "flatbuffers/util.h"
 #include "flatbuffers/code_generators.h"
-#include <algorithm>
 
 namespace flatbuffers {
 
@@ -204,7 +203,14 @@ class GeneralGenerator : public BaseGenerator {
     if (!classcode.length()) return true;
 
     std::string code;
-    code = code + "// " + FlatBuffersGeneratedWarning();
+    if (lang_.language == IDLOptions::kCSharp) {
+      code = "// <auto-generated>\n" 
+             "//  " + std::string(FlatBuffersGeneratedWarning()) + "\n"
+             "// </auto-generated>\n\n";
+    } else {
+      code = "// " + std::string(FlatBuffersGeneratedWarning()) + "\n\n";
+    }
+
     std::string namespace_name = FullNamespace(".", ns);
     if (!namespace_name.empty()) {
       code += lang_.namespace_ident + namespace_name + lang_.namespace_begin;

src/idl_gen_go.cpp

@@ -773,7 +773,7 @@ class GoGenerator : public BaseGenerator {
   void BeginFile(const std::string name_space_name, const bool needs_imports,
                  std::string *code_ptr) {
     std::string &code = *code_ptr;
-    code = code + "// " + FlatBuffersGeneratedWarning();
+    code = code + "// " + FlatBuffersGeneratedWarning() + "\n\n";
     code += "package " + name_space_name + "\n\n";
     if (needs_imports) {
       code += "import (\n";

src/idl_gen_js.cpp

@@ -92,7 +92,7 @@ class JsGenerator : public BaseGenerator {
     generateImportDependencies(&import_code, imported_files);
     generateReexports(&import_code, reexports, imported_files);
 
-    code = code + "// " + FlatBuffersGeneratedWarning();
+    code = code + "// " + FlatBuffersGeneratedWarning() + "\n\n";
 
     // Generate code for all the namespace declarations.
     GenNamespaces(&code, &exports_code);

src/idl_gen_php.cpp

@@ -66,7 +66,7 @@ namespace php {
                      const bool needs_imports, std::string *code_ptr) {
         std::string &code = *code_ptr;
         code += "<?php\n";
-        code = code + "// " + FlatBuffersGeneratedWarning();
+        code = code + "// " + FlatBuffersGeneratedWarning() + "\n\n";
         code += "namespace " + name_space_name + ";\n\n";
 
         if (needs_imports) {

src/idl_gen_python.cpp

@@ -630,7 +630,7 @@ class PythonGenerator : public BaseGenerator {
   void BeginFile(const std::string name_space_name, const bool needs_imports,
                  std::string *code_ptr) {
     std::string &code = *code_ptr;
-    code = code + "# " + FlatBuffersGeneratedWarning();
+    code = code + "# " + FlatBuffersGeneratedWarning() + "\n\n";
     code += "# namespace: " + name_space_name + "\n\n";
     if (needs_imports) {
       code += "import flatbuffers\n\n";

tests/MyGame/Example/Ability.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example/Any.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example/Color.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example/Monster.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example/Stat.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example/Test.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example/TestSimpleTableWithEnum.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example/Vec3.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example
 {

tests/MyGame/Example2/Monster.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace MyGame.Example2
 {

tests/namespace_test/NamespaceA/NamespaceB/EnumInNestedNS.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace NamespaceA.NamespaceB
 {

tests/namespace_test/NamespaceA/NamespaceB/StructInNestedNS.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace NamespaceA.NamespaceB
 {

tests/namespace_test/NamespaceA/NamespaceB/TableInNestedNS.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace NamespaceA.NamespaceB
 {

tests/namespace_test/NamespaceA/SecondTableInA.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace NamespaceA
 {

tests/namespace_test/NamespaceA/TableInFirstNS.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace NamespaceA
 {

tests/namespace_test/NamespaceC/TableInC.cs

-// automatically generated by the FlatBuffers compiler, do not modify
+// <auto-generated>
+//  automatically generated by the FlatBuffers compiler, do not modify
+// </auto-generated>
 
 namespace NamespaceC
 {