Add Entity protocol extension for @Entity macro

Author: colemancda

Sources/CoreModel/Macros.swift

@@ -6,6 +6,7 @@
 //
 
 @attached(member, names: arbitrary)
+@attached(extension, conformances: CoreModel.Entity)
 public macro Entity(_ name: String? = nil) = #externalMacro(
     module: "CoreModelMacros",
     type: "EntityMacro"

Sources/CoreModelMacros/Entity.swift

@@ -13,7 +13,7 @@ import SwiftSyntaxMacros
 /// `@Entity` macro
 ///
 /// Adds protocol conformance and implementaion for entity name.
-public struct EntityMacro: MemberMacro {
+public struct EntityMacro: MemberMacro, ExtensionMacro {
 
     public static var expansionNames: [String] {
         [
@@ -23,6 +23,34 @@ public struct EntityMacro: MemberMacro {
         ]
     }
 
+    // Add protocol conformance via extension
+    public static func expansion(
+        of node: AttributeSyntax,
+        attachedTo declaration: some DeclGroupSyntax,
+        providingExtensionsOf type: some TypeSyntaxProtocol,
+        conformingTo protocols: [TypeSyntax],
+        in context: some MacroExpansionContext
+    ) throws -> [ExtensionDeclSyntax] {
+        let extensionDecl = ExtensionDeclSyntax(
+            leadingTrivia: nil,
+            attributes: [],
+            modifiers: [],
+            extensionKeyword: .keyword(.extension),
+            extendedType: TypeSyntax(type),
+            inheritanceClause: InheritanceClauseSyntax(
+                colon: .colonToken(trailingTrivia: .space),
+                inheritedTypes: InheritedTypeListSyntax {
+                    InheritedTypeSyntax(
+                        type: TypeSyntax(stringLiteral: "CoreModel.Entity")
+                    )
+                }
+            ),
+            genericWhereClause: nil,
+            memberBlock: MemberBlockSyntax(members: [])
+        )
+        return [extensionDecl]
+    }
+    
     public static func expansion(
         of node: AttributeSyntax,
         providingMembersOf declaration: some DeclGroupSyntax,