Improve metadata debug functionality with better field handling (#182)

Author: Kyle-Ye

Sources/OpenAttributeGraphShims/Metadata+Debug.swift

@@ -42,7 +42,7 @@ extension Metadata {
         switch kind {
         case .enum:
             write(&result, string: "enum \(type) {", level: level)
-            _ = forEachField(options: [.enumerateEnumCases]) { name, offset, type in // anything contains ._4 will work here
+            _ = forEachField(options: [.enumerateEnumCases]) { name, offset, type in
                 let fieldName = String(cString: name)
                 write(&result, string: "case \(fieldName)(\(type)) // offset = \(offset.hex)", level: level+1)
                 if recursive {
@@ -52,7 +52,7 @@ extension Metadata {
             }
             write(&result, string: "}", level: level)
         case .optional:
-            _ = forEachField(options: [.enumerateEnumCases]) { name, offset, type in // anything contains ._4 will work here
+            _ = forEachField(options: [.enumerateEnumCases]) { name, offset, type in
                 let fieldName = String(cString: name)
                 write(&result, string: "case \(fieldName)(\(type)) // offset = \(offset.hex)", level: level+1)
                 if recursive {
@@ -62,7 +62,7 @@ extension Metadata {
             }
         case .struct:
             write(&result, string: "struct \(type) {", level: level)
-            _ = forEachField(options: []) { name, offset, type in // only [] and [._2] will work here
+            _ = forEachField(options: [.continueAfterUnknownField]) { name, offset, type in
                 let fieldName = String(cString: name)
                 write(&result, string: "var \(fieldName): \(type) // offset = \(offset.hex)", level: level+1)
                 if recursive {
@@ -74,7 +74,7 @@ extension Metadata {
         case .tuple: break
         case .class:
             write(&result, string: "class \(type) {", level: level)
-            _ = forEachField(options: [.enumerateClassFields]) { name, offset, type in // anything contains ._1 will work here
+            _ = forEachField(options: [.enumerateClassFields, .continueAfterUnknownField]) { name, offset, type in
                 let fieldName = String(cString: name)
 
                 write(&result, string: "var \(fieldName): \(type) // offset = \(offset.hex)", level: level+1)

Tests/OpenAttributeGraphShimsTests/MetadataDebugTests.swift

@@ -5,6 +5,14 @@
 @_spi(Debug) import OpenAttributeGraphShims
 import Testing
 
+#if canImport(UIKit)
+import UIKit
+private typealias PlatformView = UIView
+#elseif canImport(AppKit)
+import AppKit
+private typealias PlatformView = NSView
+#endif
+
 @Suite(.disabled(if: !attributeGraphEnabled, "forEachField is not implemented for OAG"))
 struct MetadataDebugTests {
     struct Demo1 {
@@ -16,7 +24,7 @@ struct MetadataDebugTests {
         var a: Int = .zero
         var b: Double = .zero
     }
-    
+
     @Test
     func layout() {
         #expect(Metadata(Demo1.self).layoutDescription == #"""
@@ -35,5 +43,25 @@ struct MetadataDebugTests {
         
         """#)
     }
-    
+
+    #if canImport(UIKit) || canImport(AppKit)
+    @Test
+    func unknownFields() {
+        class DemoView: PlatformView {
+            var a: Int = .zero
+            var b: Double = .zero
+        }
+        let layoutDescription = Metadata(DemoView.self).layoutDescription.split(separator: "\n").map(String.init)
+        #expect(layoutDescription[0] == "class DemoView {")
+        #expect(layoutDescription[1].contains("var a: Int // offset = "))
+        #expect(layoutDescription[2].contains("var b: Double // offset = "))
+        #expect(layoutDescription[3] == "}")
+    }
+    #endif
+}
+
+extension Int {
+    fileprivate var hex: String {
+        "0x\(String(format:"%X", self))"
+    }
 }