[feat] discardableResult 및 참조 타입 코드 생성 방식 수정

Author: ShapeKim98

Sources/DelegationMacros/ControllableMacro.swift

@@ -174,14 +174,24 @@ public struct ControllableMacro: PeerMacro {
         }
 
         let callPrefix = ControllableMacroSupport.callPrefix(for: functionDecl.signature)
-        let copyKeyword = ControllableMacroSupport.requiresMutableCopy(functionDecl.modifiers) ? "var" : "let"
         let arguments = ControllableMacroSupport.argumentList(from: functionDecl.signature.parameterClause)
-        let invocation = arguments.isEmpty ? "controllable.\(identifier)()" : "controllable.\(identifier)(\(arguments))"
-        let bodyLines = [
-            "    \(copyKeyword) controllable = self",
-            "    let _: Void = \(callPrefix)\(invocation)",
-            "    return controllable"
-        ]
+        let isReferenceType = MacroSupport.isReferenceTypeContext(for: functionDecl)
+        let requiresCopy = ControllableMacroSupport.requiresMutableCopy(functionDecl.modifiers) && !isReferenceType
+
+        let invocationTarget = requiresCopy ? "controllable" : "self"
+        let invocation = arguments.isEmpty
+            ? "\(invocationTarget).\(identifier)()"
+            : "\(invocationTarget).\(identifier)(\(arguments))"
+
+        var bodyLines: [String] = []
+        if requiresCopy {
+            bodyLines.append("    var controllable = self")
+            bodyLines.append("    let _: Void = \(callPrefix)\(invocation)")
+            bodyLines.append("    return controllable")
+        } else {
+            bodyLines.append("    let _: Void = \(callPrefix)\(invocation)")
+            bodyLines.append("    return self")
+        }
 
         var lines: [String] = []
         if !attributesText.isEmpty {

Sources/DelegationMacros/DelegatableMacro.swift

@@ -83,13 +83,27 @@ public struct DelegatableMacro: PeerMacro {
         let accessModifier = MacroSupport.enclosingAccessModifier(for: varDecl)
         let accessModifierText = accessModifier.map { "\($0.text) " } ?? ""
 
-        let functionDecl: DeclSyntax = """
-            \(raw: accessModifierText)func \(raw: propertyName)(_ perform: @escaping \(raw: parameterTypeDescription)) -> Self {
-                var delegator = self
-                delegator.\(raw: propertyName) = perform
-                return delegator
-            }
-            """
+        let isReferenceType = MacroSupport.isReferenceTypeContext(for: varDecl)
+        let functionDecl: DeclSyntax
+
+        if isReferenceType {
+            functionDecl = """
+                @discardableResult
+                \(raw: accessModifierText)func \(raw: propertyName)(_ perform: @escaping \(raw: parameterTypeDescription)) -> Self {
+                    self.\(raw: propertyName) = perform
+                    return self
+                }
+                """
+        } else {
+            functionDecl = """
+                @discardableResult
+                \(raw: accessModifierText)func \(raw: propertyName)(_ perform: @escaping \(raw: parameterTypeDescription)) -> Self {
+                    var delegator = self
+                    delegator.\(raw: propertyName) = perform
+                    return delegator
+                }
+                """
+        }
 
         return [functionDecl]
     }

Sources/DelegationMacros/MacroSupport.swift

@@ -21,6 +21,24 @@ enum MacroSupport {
         accessModifier(from: enclosingDeclModifierList(for: declaration))
     }
 
+    static func isReferenceTypeContext(for declaration: some SyntaxProtocol) -> Bool {
+        var currentParent = Syntax(declaration).parent
+
+        while let parent = currentParent {
+            if parent.is(ClassDeclSyntax.self) || parent.is(ActorDeclSyntax.self) {
+                return true
+            }
+
+            if parent.is(StructDeclSyntax.self) || parent.is(EnumDeclSyntax.self) {
+                return false
+            }
+
+            currentParent = parent.parent
+        }
+
+        return false
+    }
+
     static func isAccessModifier(_ modifier: DeclModifierSyntax) -> Bool {
         switch modifier.name.tokenKind {
         case .keyword(.public),