From 3f66d9dbd3be53c15c7d678eb26b664afb6a0dbe Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Thu, 13 Aug 2026 06:05:03 +0000
Subject: [PATCH] Remove distinction of enum and flags-enum for ShapeTag

Unified the ShapeTag prefix generation for regular enums and [Flags] enums under "enum:", removing the "flags:" prefix entirely and deleting the unused HasFlagsAttribute helper method. Updated the tests to match.
---
 src/ZeroSerializerGenerator.cs | 22 +---------------------
 tests/ShapeTagAndHashTests.cs  |  2 +-
 2 files changed, 2 insertions(+), 22 deletions(-)

diff --git a/src/ZeroSerializerGenerator.cs b/src/ZeroSerializerGenerator.cs
index ba279b0..5cc1985 100644
--- a/src/ZeroSerializerGenerator.cs
+++ b/src/ZeroSerializerGenerator.cs
@@ -1662,7 +1662,7 @@ private static void CreateShapeTag(ITypeSymbol typeSymbol, StringBuilder shapeTa
 
         if (typeSymbol.TypeKind == TypeKind.Enum && typeSymbol is INamedTypeSymbol enumType)
         {
-            string prefix = HasFlagsAttribute(enumType) ? "flags:" : "enum:";
+            string prefix = "enum:";
             string underlyingName = GetPrimitiveKeyword(enumType.EnumUnderlyingType);
             if (underlyingName.Length == 0)
             {
@@ -1727,24 +1727,4 @@ private static string GetPrimitiveKeyword(ITypeSymbol? typeSymbol)
         };
     }
 
-    private static bool HasFlagsAttribute(INamedTypeSymbol enumType)
-    {
-        foreach (AttributeData attr in enumType.GetAttributes())
-        {
-            if (attr.AttributeClass is INamedTypeSymbol
-                {
-                    Name: "FlagsAttribute", ContainingNamespace: INamespaceSymbol
-                    {
-                        Name: "System", ContainingNamespace: INamespaceSymbol
-                        {
-                            IsGlobalNamespace: true
-                        }
-                    }
-                })
-            {
-                return true;
-            }
-        }
-        return false;
-    }
 }
diff --git a/tests/ShapeTagAndHashTests.cs b/tests/ShapeTagAndHashTests.cs
index 6209a37..b11478b 100644
--- a/tests/ShapeTagAndHashTests.cs
+++ b/tests/ShapeTagAndHashTests.cs
@@ -47,7 +47,7 @@ public void EnumClassViewTest()
     [Fact]
     public void SchemaSignatureTestsModelViewTest()
     {
-        string schemaSignatureExpected = "v1/{blittable{int,enum:short},{int,enum:byte},blittable{int,enum:short}[],{},blittable{},{enum:byte,enum:short}?,enum:byte[],flags:ulong[],int?,bool?}";
+        string schemaSignatureExpected = "v1/{blittable{int,enum:short},{int,enum:byte},blittable{int,enum:short}[],{},blittable{},{enum:byte,enum:short}?,enum:byte[],enum:ulong[],int?,bool?}";
         Assert.Equal(SchemaSignatureTestsModelView.ShapeTag, schemaSignatureExpected);
         Assert.Equal(SchemaSignatureTestsModelView.ShapeHash, XXHash32.HashToUInt32(schemaSignatureExpected));
     }