Update TransformCollectionAndObjectInitializers to check for init-only properties

Author: nikitalita

ICSharpCode.Decompiler/IL/Transforms/TransformCollectionAndObjectInitializers.cs

@@ -58,6 +58,7 @@ void IStatementTransform.Run(Block block, int pos, StatementTransformContext con
 			{
 				case NewObj newObjInst:
 					if (newObjInst.ILStackWasEmpty && v.Kind == VariableKind.Local
+						&& !TypeContainsInitOnlyProperties(newObjInst.Method.DeclaringType.GetDefinition())
 						&& !currentMethod.IsConstructor
 						&& !currentMethod.IsCompilerGeneratedOrIsInCompilerGeneratedClass())
 					{
@@ -187,6 +188,18 @@ void IStatementTransform.Run(Block block, int pos, StatementTransformContext con
 			ILInlining.InlineIfPossible(block, pos, context);
 		}
 
+		private static bool TypeContainsInitOnlyProperties(ITypeDefinition? typeDefinition)
+		{
+			foreach (var property in typeDefinition?.Properties ?? [])
+			{
+				if (property.Setter?.IsInitOnly ?? false)
+				{
+					return true;
+				}
+			}
+			return false;
+		}
+
 		internal static bool IsRecordCloneMethodCall(CallInstruction ci)
 		{
 			if (ci.Method.DeclaringTypeDefinition?.IsRecord != true)

ICSharpCode.Decompiler/NRExtensions.cs

@@ -73,6 +73,18 @@ public static bool ContainsAnonymousType(this IType type)
 			return visitor.ContainsAnonType;
 		}
 
+		public static bool ContainsInitOnlyProperties(this IType type)
+		{
+			foreach (var property in type.GetDefinition()?.Properties ?? [])
+			{
+				if (property.Setter?.IsInitOnly ?? false)
+				{
+					return true;
+				}
+			}
+			return false;
+		}
+
 		class ContainsAnonTypeVisitor : TypeVisitor
 		{
 			public bool ContainsAnonType;