From 93f74c0363dc4ca308e573303c17f25dde4bc26d Mon Sep 17 00:00:00 2001
From: Marc Butler <mockbutler@gmail.com>
Date: Fri, 31 May 2019 08:57:41 +1000
Subject: [PATCH] Generate FlagsAttribute for Csharp (#5370)

For schema enums with the bit_flags attribute, generate the
corresponding System.FlagsAttribute in generated Csharp code.
---
 src/idl_gen_general.cpp       | 5 +++++
 tests/MyGame/Example/Color.cs | 1 +
 2 files changed, 6 insertions(+)

diff --git a/src/idl_gen_general.cpp b/src/idl_gen_general.cpp
index d4338e3ad..ddaae8f4e 100644
--- a/src/idl_gen_general.cpp
+++ b/src/idl_gen_general.cpp
@@ -510,6 +510,11 @@ class GeneralGenerator : public BaseGenerator {
     std::string &code = *code_ptr;
     if (enum_def.generated) return;
 
+    // In C# this indicates enumeration values can be treated as bit flags.
+    if (lang_.language == IDLOptions::kCSharp && enum_def.attributes.Lookup("bit_flags")) {
+        code += "[System.FlagsAttribute]\n";
+    }
+
     // Generate enum definitions of the form:
     // public static (final) int name = value;
     // In Java, we use ints rather than the Enum feature, because we want them
diff --git a/tests/MyGame/Example/Color.cs b/tests/MyGame/Example/Color.cs
index 654b16315..897ccc122 100644
--- a/tests/MyGame/Example/Color.cs
+++ b/tests/MyGame/Example/Color.cs
@@ -5,6 +5,7 @@
 namespace MyGame.Example
 {
 
+[System.FlagsAttribute]
 public enum Color : byte
 {
  Red = 1,