Add and implement TransformEnums IdentifyFlags config option

Author: Exanite

sources/SilkTouch/SilkTouch/Mods/Common/AttributeUtils.cs

@@ -68,7 +68,8 @@ this MethodDeclarationSyntax node
                                 && (
                                     y.ArgumentList?.Arguments.All(z =>
                                         z.NameEquals?.Name.ToString() != "EntryPoint"
-                                    ) ?? true
+                                    )
+                                    ?? true
                                 )
                                     ? y.AddArgumentListArguments(
                                         AttributeArgument(
@@ -264,6 +265,22 @@ public static bool TryGetNativeName(
         return nativeName != null;
     }
 
+    /// <summary>
+    /// Ensures the attribute list contains the [Flags] attribute.
+    /// </summary>
+    public static SyntaxList<AttributeListSyntax> WithFlags(
+        this IEnumerable<AttributeListSyntax> attributeLists
+    )
+    {
+        var list = List([.. attributeLists]);
+        if (list.ContainsAttribute("System.Flags"))
+        {
+            return list;
+        }
+
+        return list.Add(AttributeList(SingletonSeparatedList(Attribute(IdentifierName("Flags")))));
+    }
+
     /// <summary>
     /// Sets or replaces the native name attribute in the given attribute list.
     /// </summary>
@@ -272,23 +289,19 @@ public static SyntaxList<AttributeListSyntax> WithNativeName(
         string nativeName
     )
     {
-        var nativeNameAttribute = AttributeList(
-            [
-                Attribute(
-                    IdentifierName("NativeName"),
-                    AttributeArgumentList(
-                        [
-                            AttributeArgument(
-                                LiteralExpression(
-                                    SyntaxKind.StringLiteralExpression,
-                                    Literal($"\"{nativeName}\"", nativeName)
-                                )
-                            ),
-                        ]
-                    )
-                ),
-            ]
-        );
+        var nativeNameAttribute = AttributeList([
+            Attribute(
+                IdentifierName("NativeName"),
+                AttributeArgumentList([
+                    AttributeArgument(
+                        LiteralExpression(
+                            SyntaxKind.StringLiteralExpression,
+                            Literal($"\"{nativeName}\"", nativeName)
+                        )
+                    ),
+                ])
+            ),
+        ]);
 
         return List(
             attributeLists

sources/SilkTouch/SilkTouch/Mods/MixKhronosData.cs

@@ -1911,11 +1911,7 @@ .. node.Members.Where(m =>
             )
             {
                 // Add [Flags] attribute
-                var flagsAttribute = AttributeList(
-                    SingletonSeparatedList(Attribute(IdentifierName("Flags")))
-                );
-
-                node = node.WithAttributeLists(node.AttributeLists.Add(flagsAttribute));
+                node = node.WithAttributeLists(node.AttributeLists.WithFlags());
             }
 
             return base.VisitEnumDeclaration(node);

sources/SilkTouch/SilkTouch/Mods/TransformEnums.cs

@@ -84,6 +84,11 @@ public record Configuration
         /// Whether to sort enum members by their value.
         /// </summary>
         public bool SortMembers { get; init; } = false;
+
+        /// <summary>
+        /// Whether to identify enum types that are likely to be [Flags] enums as [Flags] enums.
+        /// </summary>
+        public bool IdentifyFlags { get; init; } = false;
     }
 
     /// <summary>
@@ -202,7 +207,7 @@ public async Task ExecuteAsync(IModContext ctx, CancellationToken ct = default)
     private static bool IsProbablyFlags(List<EnumMemberInfo> members)
     {
         var values = members.Where(m => m.Value != null).Select(m => m.Value!.Value).ToArray();
-        var countWith1BitSet = values.Count(x => BitOperations.PopCount((ulong)x) == 1);
+        var countWith1BitSet = values.Count(x => BitOperations.PopCount(unchecked((ulong)x)) == 1);
         return (
                 // There is more than one member
                 members.Count > 1
@@ -282,6 +287,13 @@ MemberRewriteDecider memberRewriteDecider
             }
 
             var isFlagsEnum = node.AttributeLists.ContainsAttribute("System.Flags");
+            var addFlagsAttribute = false;
+            if (!isFlagsEnum && config.IdentifyFlags && IsProbablyFlags(members))
+            {
+                isFlagsEnum = true;
+                addFlagsAttribute = true;
+            }
+
             if (isFlagsEnum && config.AddNoneMemberToFlags)
             {
                 // Add None member if it doesn't exist yet
@@ -477,6 +489,11 @@ MemberRewriteDecider memberRewriteDecider
 
             node = node.WithMembers([.. members.Select(m => m.Node)]);
 
+            if (addFlagsAttribute)
+            {
+                node = node.WithAttributeLists(node.AttributeLists.WithFlags());
+            }
+
             return base.VisitEnumDeclaration(node);
         }