Include "associated constants" in enum declarations

Closes microsoft#1027
scorteanucosmin · Jan 11, 2024 · 7f4d00f · 7f4d00f
1 parent 77ae66f
commit 7f4d00f
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Showing 4 changed files with 84 additions and 13 deletions.
diff --git a/src/Microsoft.Windows.CsWin32/Generator.Enum.cs b/src/Microsoft.Windows.CsWin32/Generator.Enum.cs
@@ -16,21 +16,20 @@ private EnumDeclarationSyntax DeclareEnum(TypeDefinition typeDef)
         TypeSyntax? enumBaseType = null;
         foreach (FieldDefinitionHandle fieldDefHandle in typeDef.GetFields())
         {
-            FieldDefinition fieldDef = this.Reader.GetFieldDefinition(fieldDefHandle);
-            string enumValueName = this.Reader.GetString(fieldDef.Name);
-            ConstantHandle valueHandle = fieldDef.GetDefaultValue();
-            if (valueHandle.IsNil)
+            AddEnumValue(fieldDefHandle);
+        }
+
+        // Add associated constants.
+        foreach (CustomAttribute associatedConstAtt in MetadataUtilities.FindAttributes(this.Reader, typeDef.GetCustomAttributes(), InteropDecorationNamespace, AssociatedConstantAttribute))
+        {
+            CustomAttributeValue<TypeSyntax> decodedAttribute = associatedConstAtt.DecodeValue(CustomAttributeTypeProvider.Instance);
+            if (decodedAttribute.FixedArguments.Length >= 1 && decodedAttribute.FixedArguments[0].Value is string constName)
             {
-                enumBaseType = fieldDef.DecodeSignature(SignatureHandleProvider.Instance, null).ToTypeSyntax(this.enumTypeSettings, GeneratingElement.EnumValue, null).Type;
-                continue;
+                if (TryFindConstant(constName, out FieldDefinitionHandle fieldHandle))
+                {
+                    AddEnumValue(fieldHandle);
+                }
             }
-
-            bool enumBaseTypeIsSigned = enumBaseType is PredefinedTypeSyntax { Keyword: { RawKind: (int)SyntaxKind.LongKeyword or (int)SyntaxKind.IntKeyword or (int)SyntaxKind.ShortKeyword or (int)SyntaxKind.SByteKeyword } };
-            ExpressionSyntax enumValue = flagsEnum ? ToHexExpressionSyntax(this.Reader, valueHandle, enumBaseTypeIsSigned) : ToExpressionSyntax(this.Reader, valueHandle);
-            EnumMemberDeclarationSyntax enumMember = EnumMemberDeclaration(SafeIdentifier(enumValueName))
-                .WithEqualsValue(EqualsValueClause(enumValue));
-            enumValues.Add(enumMember);
-            enumValues.Add(TokenWithLineFeed(SyntaxKind.CommaToken));
         }
 
         if (enumBaseType is null)
@@ -58,5 +57,38 @@ private EnumDeclarationSyntax DeclareEnum(TypeDefinition typeDef)
         result = this.AddApiDocumentation(name, result);
 
         return result;
+
+        void AddEnumValue(FieldDefinitionHandle fieldDefHandle)
+        {
+            FieldDefinition fieldDef = this.Reader.GetFieldDefinition(fieldDefHandle);
+            string enumValueName = this.Reader.GetString(fieldDef.Name);
+            ConstantHandle valueHandle = fieldDef.GetDefaultValue();
+            if (valueHandle.IsNil)
+            {
+                enumBaseType = fieldDef.DecodeSignature(SignatureHandleProvider.Instance, null).ToTypeSyntax(this.enumTypeSettings, GeneratingElement.EnumValue, null).Type;
+                return;
+            }
+
+            bool enumBaseTypeIsSigned = enumBaseType is PredefinedTypeSyntax { Keyword: { RawKind: (int)SyntaxKind.LongKeyword or (int)SyntaxKind.IntKeyword or (int)SyntaxKind.ShortKeyword or (int)SyntaxKind.SByteKeyword } };
+            ExpressionSyntax enumValue = flagsEnum ? ToHexExpressionSyntax(this.Reader, valueHandle, enumBaseTypeIsSigned) : ToExpressionSyntax(this.Reader, valueHandle);
+            EnumMemberDeclarationSyntax enumMember = EnumMemberDeclaration(SafeIdentifier(enumValueName))
+                .WithEqualsValue(EqualsValueClause(enumValue));
+            enumValues.Add(enumMember);
+            enumValues.Add(TokenWithLineFeed(SyntaxKind.CommaToken));
+        }
+
+        bool TryFindConstant(string name, out FieldDefinitionHandle fieldDefinitionHandle)
+        {
+            foreach (var ns in this.MetadataIndex.MetadataByNamespace)
+            {
+                if (ns.Value.Fields.TryGetValue(name, out fieldDefinitionHandle))
+                {
+                    return true;
+                }
+            }
+
+            fieldDefinitionHandle = default;
+            return false;
+        }
     }
 }
diff --git a/src/Microsoft.Windows.CsWin32/Generator.Invariants.cs b/src/Microsoft.Windows.CsWin32/Generator.Invariants.cs
@@ -11,6 +11,7 @@ public partial class Generator
     internal const string RAIIFreeAttribute = "RAIIFreeAttribute";
     internal const string DoNotReleaseAttribute = "DoNotReleaseAttribute";
     internal const string AssociatedEnumAttribute = "AssociatedEnumAttribute";
+    internal const string AssociatedConstantAttribute = "AssociatedConstantAttribute";
     internal const string GlobalNamespacePrefix = "global::";
     internal const string GlobalWinmdRootNamespaceAlias = "winmdroot";
     internal const string WinRTCustomMarshalerClass = "WinRTCustomMarshaler";

diff --git a/src/Microsoft.Windows.CsWin32/MetadataUtilities.cs b/src/Microsoft.Windows.CsWin32/MetadataUtilities.cs
@@ -93,4 +93,19 @@ internal static bool IsAttribute(MetadataReader reader, CustomAttribute attribut
 
         return null;
     }
+
+    internal static IEnumerable<CustomAttribute> FindAttributes(MetadataReader reader, CustomAttributeHandleCollection? customAttributeHandles, string attributeNamespace, string attributeName)
+    {
+        if (customAttributeHandles is not null)
+        {
+            foreach (CustomAttributeHandle handle in customAttributeHandles)
+            {
+                CustomAttribute att = reader.GetCustomAttribute(handle);
+                if (IsAttribute(reader, att, attributeNamespace, attributeName))
+                {
+                    yield return att;
+                }
+            }
+        }
+    }
 }
diff --git a/test/Microsoft.Windows.CsWin32.Tests/EnumTests.cs b/test/Microsoft.Windows.CsWin32.Tests/EnumTests.cs
@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+public class EnumTests : GeneratorTestBase
+{
+    public EnumTests(ITestOutputHelper logger)
+        : base(logger)
+    {
+    }
+
+    [Fact]
+    public void EnumsIncludeAssociatedConstants()
+    {
+        this.GenerateApi("SERVICE_ERROR");
+        EnumDeclarationSyntax enumDecl = Assert.IsType<EnumDeclarationSyntax>(this.FindGeneratedType("SERVICE_ERROR").Single());
+
+        // The enum should contain the constant.
+        Assert.Contains(enumDecl.Members, value => value.Identifier.ValueText == "SERVICE_NO_CHANGE");
+
+        // The constant should not be generated as a separate constant.
+        Assert.Empty(this.FindGeneratedConstant("SERVICE_NO_CHANGE"));
+    }
+}