Refactored GlobalActorIsolation type

Sources/PrincipleMacros/Builders/Declarations/Common/DeclBuilder.swift

@@ -26,15 +26,13 @@ extension DeclBuilder {
         )
     }
 
-    public var inheritedGlobalActorIsolation: AttributeSyntax? {
-        let globalActor: AttributeSyntax? = switch settings.globalActorIsolationPreference {
-        case .nonisolated:
-            nil
-        case let .isolated(globalActor):
-            "@\(globalActor)"
-        case .none:
-            basicDeclaration.globalActor?.trimmed
+    public var inheritedGlobalActorIsolation: GlobalActorIsolation? {
+        if let preferred = settings.preferredGlobalActorIsolation {
+            return preferred
         }
-        return globalActor?.withTrailingSpace
+        if let inferred = basicDeclaration.globalActor?.attributeName {
+            return .isolated(inferred)
+        }
+        return .nonisolated
     }
 }

Sources/PrincipleMacros/Builders/Declarations/Common/DeclBuilderSettings.swift

@@ -11,14 +11,14 @@ import SwiftSyntax
 public struct DeclBuilderSettings {
 
     public var accessControlLevel: AccessControlLevel
-    public var globalActorIsolationPreference: GlobalActorIsolationPreference?
+    public var preferredGlobalActorIsolation: GlobalActorIsolation?
 
     public init(
         accessControlLevel: AccessControlLevel,
-        globalActorIsolationPreference: GlobalActorIsolationPreference? = nil
+        preferredGlobalActorIsolation: GlobalActorIsolation? = nil
     ) {
         self.accessControlLevel = accessControlLevel
-        self.globalActorIsolationPreference = globalActorIsolationPreference
+        self.preferredGlobalActorIsolation = preferredGlobalActorIsolation
     }
 }
 

Sources/PrincipleMacros/Parameters/ParameterExtractor.swift

@@ -64,9 +64,9 @@ public struct ParameterExtractor {
         return rawString
     }
 
-    public func globalActorIsolationPreference(
+    public func preferredGlobalActorIsolation(
         withLabel label: TokenSyntax?
-    ) throws -> GlobalActorIsolationPreference? {
+    ) throws -> GlobalActorIsolation? {
         guard let expression = expression(withLabel: label) else {
             return nil
         }
@@ -77,8 +77,8 @@ public struct ParameterExtractor {
 
         if let memberAccessExpression = MemberAccessExprSyntax(expression),
            memberAccessExpression.declName.baseName.tokenKind == .keyword(.self),
-           let baseType = memberAccessExpression.base {
-            return .isolated("\(baseType)")
+           let globalActor = memberAccessExpression.base?.trimmed {
+            return .isolated("\(globalActor)")
         }
 
         throw ParameterExtractionError.unexpectedSyntaxType

Sources/PrincipleMacros/Syntax/Helpers/GlobalActorIsolation.swift

@@ -0,0 +1,31 @@
+//
+//  GlobalActorIsolation.swift
+//  PrincipleMacros
+//
+//  Created by Kamil Strzelecki on 18/08/2025.
+//  Copyright © 2025 Kamil Strzelecki. All rights reserved.
+//
+
+import SwiftSyntax
+
+public enum GlobalActorIsolation: Hashable {
+
+    case nonisolated
+    case isolated(TypeSyntax)
+
+    public var type: TypeSyntax? {
+        switch self {
+        case let .isolated(type):
+            type
+        case .nonisolated:
+            nil
+        }
+    }
+
+    public var attribute: AttributeSyntax? {
+        guard let type else {
+            return nil
+        }
+        return AttributeSyntax(attributeName: type)
+    }
+}

Tests/PrincipleMacrosTests/Parameters/ParameterExtractorTests.swift

@@ -46,16 +46,14 @@ extension ParameterExtractorTests {
     func testTrailingClosureExtraction() throws {
         let extractor = try makeExtractor(from: "#MyMacro { _ in }")
         let extracted = try extractor.trailingClosure(withLabel: "operation")
-        let expected: ExprSyntax = "{ _ in }"
-        #expect(extracted?.description == expected.description)
+        #expect(extracted?.description == "{ _ in }")
     }
 
     @Test
     func testTrailingClosureReferenceExtraction() throws {
         let extractor = try makeExtractor(from: "#MyMacro(operation: perform)")
         let extracted = try extractor.trailingClosure(withLabel: "operation")
-        let expected: ExprSyntax = "perform"
-        #expect(extracted?.description == expected.description)
+        #expect(extracted?.description == "perform")
     }
 }
 
@@ -80,16 +78,16 @@ extension ParameterExtractorTests {
 extension ParameterExtractorTests {
 
     @Test
-    func testMissingGlobalActorPreferenceExtraction() throws {
+    func testMissingPreferredGlobalActorExtraction() throws {
         let extractor = try makeExtractor(from: "#MyMacro()")
-        let extracted = try extractor.globalActorIsolationPreference(withLabel: "isolation")
+        let extracted = try extractor.preferredGlobalActorIsolation(withLabel: "isolation")
         #expect(extracted == nil)
     }
 
     @Test
-    func testNonisolatedGlobalActorPreferenceExtraction() throws {
+    func testNonisolatedPreferredGlobalActorExtraction() throws {
         let extractor = try makeExtractor(from: "#MyMacro(isolation: nil)")
-        let extracted = try extractor.globalActorIsolationPreference(withLabel: "isolation")
+        let extracted = try extractor.preferredGlobalActorIsolation(withLabel: "isolation")
         #expect(extracted == .nonisolated)
     }
 
@@ -99,23 +97,17 @@ extension ParameterExtractorTests {
             "SomeType.SomeActor"
         ]
     )
-    func testIsolatedGlobalActorPreferenceExtraction(isolation: String) throws {
+    func testIsolatedPreferredGlobalActorExtraction(isolation: String) throws {
         let extractor = try makeExtractor(from: "#MyMacro(isolation: \(raw: isolation).self)")
-        let extracted = try extractor.globalActorIsolationPreference(withLabel: "isolation")
-
-        switch extracted {
-        case let .isolated(globalActor):
-            #expect(globalActor.description == isolation)
-        default:
-            Issue.record()
-        }
+        let extracted = try extractor.preferredGlobalActorIsolation(withLabel: "isolation")
+        #expect(extracted?.attribute?.description == "@\(isolation)")
     }
 
     @Test
-    func testUnexpectedSyntaxWhenPerformingGlobalActorPreferenceExtraction() throws {
+    func testUnexpectedSyntaxWhenPerformingPreferredGlobalActorExtraction() throws {
         let extractor = try makeExtractor(from: #"#MyMacro(isolation: MainActor.Type)"#)
         #expect(throws: ParameterExtractionError.unexpectedSyntaxType) {
-            try extractor.globalActorIsolationPreference(withLabel: "isolation")
+            try extractor.preferredGlobalActorIsolation(withLabel: "isolation")
         }
     }
 }