From 8355a6ad3e437f770de3018e3023f91b471d778f Mon Sep 17 00:00:00 2001
From: ElektroKill <elektrokilldev@protonmail.com>
Date: Mon, 18 Sep 2023 21:06:09 +0200
Subject: [PATCH] Improve support for special attribute usages in BAML
 decompiler

---
 Extensions/dnSpy.BamlDecompiler/BamlDisassembler.cs      | 2 +-
 .../Handlers/Records/PropertyHandler.cs                  | 9 +++++++++
 Extensions/dnSpy.BamlDecompiler/Xaml/XamlProperty.cs     | 2 ++
 Extensions/dnSpy.BamlDecompiler/Xaml/XamlPropertyKind.cs | 9 +++++++++
 Extensions/dnSpy.BamlDecompiler/XamlContext.cs           | 6 +++++-
 5 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 Extensions/dnSpy.BamlDecompiler/Xaml/XamlPropertyKind.cs

diff --git a/Extensions/dnSpy.BamlDecompiler/BamlDisassembler.cs b/Extensions/dnSpy.BamlDecompiler/BamlDisassembler.cs
index 5514e75c73..17438cb273 100644
--- a/Extensions/dnSpy.BamlDecompiler/BamlDisassembler.cs
+++ b/Extensions/dnSpy.BamlDecompiler/BamlDisassembler.cs
@@ -523,7 +523,7 @@ void DisassembleRecord(BamlContext ctx, AttributeInfoRecord record) {
 				WriteFlagField("XmlSpace");
 				break;
 			case BamlAttributeUsage.RuntimeName:
-				WriteFlagField("XmlSpace");
+				WriteFlagField("RuntimeName");
 				break;
 			default:
 				WriteHexNumber((byte)record.AttributeUsage);
diff --git a/Extensions/dnSpy.BamlDecompiler/Handlers/Records/PropertyHandler.cs b/Extensions/dnSpy.BamlDecompiler/Handlers/Records/PropertyHandler.cs
index 1aba6c5a84..38aaa0bf74 100644
--- a/Extensions/dnSpy.BamlDecompiler/Handlers/Records/PropertyHandler.cs
+++ b/Extensions/dnSpy.BamlDecompiler/Handlers/Records/PropertyHandler.cs
@@ -42,6 +42,15 @@ public BamlElement Translate(XamlContext ctx, BamlNode node, BamlElement parent)
 			return null;
 
 			XAttribute ConstructXAttribute() {
+				switch (xamlProp.PropertyKind) {
+				case XamlPropertyKind.XmlSpace:
+					return new XAttribute(XNamespace.Xml + "space", value);
+				case XamlPropertyKind.XmlLang:
+					return new XAttribute(XNamespace.Xml + "lang", value);
+				case XamlPropertyKind.RuntimeName:
+					return new XAttribute(ctx.GetKnownNamespace("Name", XamlContext.KnownNamespace_Xaml), value);
+				}
+
 				if (xamlProp.IsAttachedTo(elemType))
 					return new XAttribute(xamlProp.ToXName(ctx, parent.Xaml), value);
 
diff --git a/Extensions/dnSpy.BamlDecompiler/Xaml/XamlProperty.cs b/Extensions/dnSpy.BamlDecompiler/Xaml/XamlProperty.cs
index 9b01623be8..a94c5eaed2 100644
--- a/Extensions/dnSpy.BamlDecompiler/Xaml/XamlProperty.cs
+++ b/Extensions/dnSpy.BamlDecompiler/Xaml/XamlProperty.cs
@@ -35,6 +35,8 @@ sealed class XamlProperty {
 
 		public ITypeDefOrRef ResolvedMemberDeclaringType { get; set; }
 
+		public XamlPropertyKind PropertyKind { get; set; }
+
 		public XamlProperty(XamlType type, string name) {
 			DeclaringType = type;
 			PropertyName = name;
diff --git a/Extensions/dnSpy.BamlDecompiler/Xaml/XamlPropertyKind.cs b/Extensions/dnSpy.BamlDecompiler/Xaml/XamlPropertyKind.cs
new file mode 100644
index 0000000000..83de5b0dcf
--- /dev/null
+++ b/Extensions/dnSpy.BamlDecompiler/Xaml/XamlPropertyKind.cs
@@ -0,0 +1,9 @@
+namespace dnSpy.BamlDecompiler.Xaml {
+	enum XamlPropertyKind : byte {
+		// Note: The order of these should remain consistent with BamlAttributeUsage!
+		Default,
+		XmlLang,
+		XmlSpace,
+		RuntimeName,
+	}
+}
diff --git a/Extensions/dnSpy.BamlDecompiler/XamlContext.cs b/Extensions/dnSpy.BamlDecompiler/XamlContext.cs
index e70ede0778..715e6e6cf8 100644
--- a/Extensions/dnSpy.BamlDecompiler/XamlContext.cs
+++ b/Extensions/dnSpy.BamlDecompiler/XamlContext.cs
@@ -123,23 +123,27 @@ public XamlProperty ResolveProperty(ushort id) {
 			XamlType type;
 			string name;
 			IMemberDef member;
+			XamlPropertyKind propertyKind;
 
 			if (id > 0x7fff) {
 				var knownProp = Baml.KnownThings.Members((KnownMembers)unchecked((short)-(short)id));
 				type = ResolveType(unchecked((ushort)(short)-(short)knownProp.Parent));
 				name = knownProp.Name;
 				member = knownProp.Property;
+				propertyKind = XamlPropertyKind.Default;
 			}
 			else {
 				var attrRec = Baml.AttributeIdMap[id];
 				type = ResolveType(attrRec.OwnerTypeId);
 				name = attrRec.Name;
+				propertyKind = (XamlPropertyKind)attrRec.AttributeUsage;
 
 				member = null;
 			}
 
 			propertyMap[id] = xamlProp = new XamlProperty(type, name) {
-				ResolvedMember = member
+				ResolvedMember = member,
+				PropertyKind = propertyKind
 			};
 			xamlProp.TryResolve();