[Rgen] Allow the transformer to keep track of nornt smart enums.

The transformer needs to be able to parse non smart enums to be able to
copy them over to the new location and to update the availability
attributes to use SupportedOS and UnsupportedOS. This changes nothing in
the code generator.

Author: mandel-macaque

src/rgen/Microsoft.Macios.Generator/DataModel/BindingType.cs

@@ -24,6 +24,10 @@ enum BindingType : ulong {
 	/// </summary>
 	Protocol,
 	/// <summary>
+	/// Binding type for a traditional enum.
+	/// </summary>
+	Enum,
+	/// <summary>
 	/// Binding type for a enum with backing fields.
 	/// </summary>
 	SmartEnum,

src/rgen/Microsoft.Macios.Transformer/DataModel/Binding.Transformer.cs

@@ -40,9 +40,12 @@ public ImmutableArray<string> Protocols {
 		init => protocols = value;
 	}
 
+	public BaseTypeDeclarationSyntax? BaseDeclarationSyntax { get; init; }
+
 	/// <summary>
 	/// Internal constructor added for testing purposes.
 	/// </summary>
+	/// <param name="declarationSyntax">The syntax used to declare the binding.</param>
 	/// <param name="name">The name of the named type that created the code change.</param>
 	/// <param name="namespace">The namespace that contains the named type.</param>
 	/// <param name="fullyQualifiedSymbol">The fully qualified name of the symbol.</param>
@@ -74,6 +77,7 @@ internal Binding (EnumDeclarationSyntax enumDeclaration, INamedTypeSymbol symbol
 			outerClasses: out outerClasses,
 			namespaces: out namespaces,
 			symbolAvailability: out availability);
+		BaseDeclarationSyntax = enumDeclaration;
 		BindingBindingInfo = new BindingInfo (null, BindingType.SmartEnum);
 		FullyQualifiedSymbol = enumDeclaration.GetFullyQualifiedIdentifier (context.SemanticModel);
 		UsingDirectives = enumDeclaration.SyntaxTree.CollectUsingStatements ();
@@ -91,24 +95,55 @@ internal Binding (EnumDeclarationSyntax enumDeclaration, INamedTypeSymbol symbol
 				continue;
 			}
 			var fieldData = enumValueSymbol.GetFieldData ();
+			EnumMember? enumMember;
 			// try and compute the library for this enum member
 			if (fieldData is null || !context.TryComputeLibraryName (fieldData.Value.LibraryName, Namespace [^1],
-					out string? libraryName, out string? libraryPath))
-				// could not calculate the library for the enum, do not add it
-				continue;
-			// we do know we have a backing field, so we can set the binding type to smart enum
-			bindingType = BindingType.SmartEnum;
-			var enumMember = new EnumMember (
-				name: enumValueDeclaration.Identifier.ToFullString ().Trim (),
-				libraryName: libraryName,
-				libraryPath: libraryPath,
-				fieldData: enumValueSymbol.GetFieldData (),
-				symbolAvailability: enumValueSymbol.GetAvailabilityForSymbol () // no parent availability, just the symbol
-			);
-			bucket.Add (enumMember);
+				    out string? libraryName, out string? libraryPath)) {
+				// create a member for those enum values that do not have a backing field, we will
+				// set the binding type to regular enum if we do not know it yet
+				if (bindingType == BindingType.Unknown) {
+					bindingType = BindingType.Enum;
+				}
+				enumMember = new EnumMember (
+					name: enumValueDeclaration.Identifier.ToFullString ().Trim (),
+					libraryName: string.Empty,
+					libraryPath: null,
+					fieldData: enumValueSymbol.GetFieldData (),
+					symbolAvailability: enumValueSymbol
+						.GetAvailabilityForSymbol () // no parent availability, just the symbol
+				) {
+					DeclarationSyntax = enumValueDeclaration,
+					IsSmartMember = false
+				};
+			} else {
+				// we do know we have a backing field, so we can set the binding type to smart enum
+				bindingType = BindingType.SmartEnum;
+				enumMember = new EnumMember (
+					name: enumValueDeclaration.Identifier.ToFullString ().Trim (),
+					libraryName: libraryName,
+					libraryPath: libraryPath,
+					fieldData: enumValueSymbol.GetFieldData (),
+					symbolAvailability: enumValueSymbol
+						.GetAvailabilityForSymbol () // no parent availability, just the symbol
+				) {
+					DeclarationSyntax = enumValueDeclaration,
+					IsSmartMember = true,
+				};
+			}
+			bucket.Add (enumMember.Value);
 		}
 
+		if (bindingType == BindingType.Unknown) {
+			// we could not find any enum member with a backing field this means that we are dealing with a regular enum
+			// we will set it so that we can convert the availability information
+			bindingType = BindingType.Enum;
+		}
 		BindingBindingInfo = new (null, bindingType);
+		// based on the type of enum we might need to remove enums that are not valid, this are enums without
+		// a backing field in the case of smart enums
+		if (BindingBindingInfo.BindingType == BindingType.SmartEnum) {
+			bucket.RemoveAll (em => !em.IsSmartMember);
+		}
 		EnumMembers = bucket.ToImmutable ();
 	}
 
@@ -236,6 +271,7 @@ internal static bool Skip (MethodDeclarationSyntax methodDeclarationSyntax, Sema
 	/// <param name="context">The current compilation context.</param>
 	internal Binding (InterfaceDeclarationSyntax interfaceDeclarationSyntax, INamedTypeSymbol symbol, in RootContext context)
 	{
+		BaseDeclarationSyntax = interfaceDeclarationSyntax;
 		// basic properties of the binding
 		FullyQualifiedSymbol = interfaceDeclarationSyntax.GetFullyQualifiedIdentifier (context.SemanticModel);
 		UsingDirectives = interfaceDeclarationSyntax.SyntaxTree.CollectUsingStatements ();

src/rgen/Microsoft.Macios.Transformer/DataModel/EnumMember.Transformer.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT License.
 
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.Macios.Generator.Availability;
 using Microsoft.Macios.Transformer.Attributes;
 
@@ -14,6 +15,12 @@ readonly partial struct EnumMember {
 	/// </summary>
 	public FieldInfo? FieldInfo { get; init; }
 
+	/// <summary>
+	/// The enum member declaration.
+	/// </summary>
+	public EnumMemberDeclarationSyntax? DeclarationSyntax { get; init; }
+
+	public bool IsSmartMember { get; init; }
 
 	/// <summary>
 	/// Return the native selector that references the enum value.

tests/rgen/Microsoft.Macios.Transformer.Tests/DataModel/SmartEnumTests.cs

@@ -97,7 +97,6 @@ public enum AVCaptureDeviceType {
 	[Field (""AVCaptureDeviceTypeBuiltInWideAngleCamera"")]
 	BuiltInWideAngleCamera,
 
-	// missing attr, this should be ignored
 	BuiltInTelephotoCamera,
 }
 ";