Fix #2297: Add an option to disable decompilation of getter-only auto properties.

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -23,6 +23,7 @@ using System.IO;
 using System.Linq;
 using System.Reflection.Metadata;
 using System.Reflection.PortableExecutable;
+using System.Text.RegularExpressions;
 using System.Threading;
 
 using ICSharpCode.Decompiler.CSharp.OutputVisitor;
@@ -329,8 +330,29 @@ namespace ICSharpCode.Decompiler.CSharp
 					{
 						if (settings.AnonymousMethods && IsAnonymousMethodCacheField(field, metadata))
 							return true;
-						if (settings.AutomaticProperties && IsAutomaticPropertyBackingField(field, metadata))
+						if (settings.AutomaticProperties && IsAutomaticPropertyBackingField(field, metadata, out var propertyName))
+						{
+							if (!settings.GetterOnlyAutomaticProperties && IsGetterOnlyProperty(propertyName))
+								return false;
+
+							bool IsGetterOnlyProperty(string propertyName)
+							{
+								var properties = metadata.GetTypeDefinition(field.GetDeclaringType()).GetProperties();
+								foreach (var p in properties)
+								{
+									var pd = metadata.GetPropertyDefinition(p);
+									string name = metadata.GetString(pd.Name);
+									if (!metadata.StringComparer.Equals(pd.Name, propertyName))
+										continue;
+									PropertyAccessors accessors = pd.GetAccessors();
+									return !accessors.Getter.IsNil && accessors.Setter.IsNil;
+								}
+								return false;
+							}
+
 							return true;
+						}
+
 						if (settings.SwitchStatementOnString && IsSwitchOnStringCache(field, metadata))
 							return true;
 					}
@@ -359,10 +381,20 @@ namespace ICSharpCode.Decompiler.CSharp
 			return metadata.GetString(field.Name).StartsWith("<>f__switch", StringComparison.Ordinal);
 		}
 
-		static bool IsAutomaticPropertyBackingField(SRM.FieldDefinition field, MetadataReader metadata)
+		static readonly Regex automaticPropertyBackingFieldRegex = new Regex(@"^<(.*)>k__BackingField$",
+			RegexOptions.Compiled | RegexOptions.CultureInvariant);
+
+		static bool IsAutomaticPropertyBackingField(SRM.FieldDefinition field, MetadataReader metadata, out string propertyName)
 		{
+			propertyName = null;
 			var name = metadata.GetString(field.Name);
-			return name.StartsWith("<", StringComparison.Ordinal) && name.EndsWith("BackingField", StringComparison.Ordinal);
+			var m = automaticPropertyBackingFieldRegex.Match(name);
+			if (m.Success)
+			{
+				propertyName = m.Groups[1].Value;
+				return true;
+			}
+			return false;
 		}
 
 		static bool IsAnonymousMethodCacheField(SRM.FieldDefinition field, MetadataReader metadata)

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -292,7 +292,8 @@ namespace ICSharpCode.Decompiler.CSharp
 			// It feels a bit hacky, though.
 			if (settings.AutomaticProperties
 				&& PatternStatementTransform.IsBackingFieldOfAutomaticProperty(field, out var property)
-				&& decompilationContext.CurrentMember != property)
+				&& decompilationContext.CurrentMember != property
+				&& (property.CanSet || settings.GetterOnlyAutomaticProperties))
 			{
 				requireTarget = RequiresQualifier(property, target);
 			}

ICSharpCode.Decompiler/CSharp/Transforms/PatternStatementTransform.cs

@@ -103,7 +103,8 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 
 		public override AstNode VisitPropertyDeclaration(PropertyDeclaration propertyDeclaration)
 		{
-			if (context.Settings.AutomaticProperties)
+			if (context.Settings.AutomaticProperties
+				&& (!propertyDeclaration.Setter.IsNull || context.Settings.GetterOnlyAutomaticProperties))
 			{
 				AstNode result = TransformAutomaticProperty(propertyDeclaration);
 				if (result != null)
@@ -738,6 +739,8 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 				if (field != null && IsBackingFieldOfAutomaticProperty(field, out var property)
 					&& CanTransformToAutomaticProperty(property) && currentMethod.AccessorOwner != property)
 				{
+					if (!property.CanSet && !context.Settings.GetterOnlyAutomaticProperties)
+						return null;
 					parent.RemoveAnnotations<MemberResolveResult>();
 					parent.AddAnnotation(new MemberResolveResult(mrr.TargetResult, property));
 					return Identifier.Create(property.Name);

ICSharpCode.Decompiler/DecompilerSettings.cs

@@ -93,6 +93,7 @@ namespace ICSharpCode.Decompiler
 				dictionaryInitializers = false;
 				extensionMethodsInCollectionInitializers = false;
 				useRefLocalsForAccurateOrderOfEvaluation = false;
+				getterOnlyAutomaticProperties = false;
 			}
 			if (languageVersion < CSharp.LanguageVersion.CSharp7)
 			{
@@ -159,7 +160,8 @@ namespace ICSharpCode.Decompiler
 				|| discards || localFunctions)
 				return CSharp.LanguageVersion.CSharp7;
 			if (awaitInCatchFinally || useExpressionBodyForCalculatedGetterOnlyProperties || nullPropagation
-				|| stringInterpolation || dictionaryInitializers || extensionMethodsInCollectionInitializers || useRefLocalsForAccurateOrderOfEvaluation)
+				|| stringInterpolation || dictionaryInitializers || extensionMethodsInCollectionInitializers
+				|| useRefLocalsForAccurateOrderOfEvaluation || getterOnlyAutomaticProperties)
 				return CSharp.LanguageVersion.CSharp6;
 			if (asyncAwait)
 				return CSharp.LanguageVersion.CSharp5;
@@ -572,6 +574,24 @@ namespace ICSharpCode.Decompiler
 			}
 		}
 
+		bool getterOnlyAutomaticProperties = true;
+
+		/// <summary>
+		/// Decompile getter-only automatic properties
+		/// </summary>
+		[Category("C# 6.0 / VS 2015")]
+		[Description("DecompilerSettings.GetterOnlyAutomaticProperties")]
+		public bool GetterOnlyAutomaticProperties {
+			get { return getterOnlyAutomaticProperties; }
+			set {
+				if (getterOnlyAutomaticProperties != value)
+				{
+					getterOnlyAutomaticProperties = value;
+					OnPropertyChanged();
+				}
+			}
+		}
+
 		bool automaticEvents = true;
 
 		/// <summary>

ILSpy/Properties/Resources.Designer.cs

@@ -927,6 +927,15 @@ namespace ICSharpCode.ILSpy.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Decompile getter-only automatic properties.
+        /// </summary>
+        public static string DecompilerSettings_GetterOnlyAutomaticProperties {
+            get {
+                return ResourceManager.GetString("DecompilerSettings.GetterOnlyAutomaticProperties", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Include XML documentation comments in the decompiled code.
         /// </summary>

ILSpy/Properties/Resources.resx

@@ -339,6 +339,9 @@ Are you sure you want to continue?</value>
   <data name="DecompilerSettings.FunctionPointers" xml:space="preserve">
     <value>Function pointers</value>
   </data>
+  <data name="DecompilerSettings.GetterOnlyAutomaticProperties" xml:space="preserve">
+    <value>Decompile getter-only automatic properties</value>
+  </data>
   <data name="DecompilerSettings.IncludeXMLDocumentationCommentsInTheDecompiledCode" xml:space="preserve">
     <value>Include XML documentation comments in the decompiled code</value>
   </data>