Fix #2280: Add additional checks to GenerateVariableName

ICSharpCode.Decompiler/CSharp/Transforms/DeclareVariables.cs

@@ -202,7 +202,10 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 						var v = function.RegisterVariable(
 							VariableKind.StackSlot,
 							type,
-							AssignVariableNames.GenerateVariableName(function, type, stmt.Expression.Annotations.OfType<ILInstruction>().Where(AssignVariableNames.IsSupportedInstruction).FirstOrDefault())
+							AssignVariableNames.GenerateVariableName(function, type,
+								stmt.Expression.Annotations.OfType<ILInstruction>()
+									.Where(AssignVariableNames.IsSupportedInstruction).FirstOrDefault(),
+								mustResolveConflicts: true)
 						);
 						stmt.Expression = new AssignmentExpression(
 							new IdentifierExpression(v.Name).WithRR(new ILVariableResolveResult(v, v.Type)),

ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs

@@ -52,7 +52,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 		};
 
 		ILTransformContext context;
-		string[] currentLowerCaseTypeOrMemberNames;
+		List<string> currentLowerCaseTypeOrMemberNames;
 		Dictionary<string, int> reservedVariableNames;
 		Dictionary<MethodDefinitionHandle, string> localFunctionMapping;
 		HashSet<ILVariable> loopCounters;
@@ -63,7 +63,16 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			this.context = context;
 
 			reservedVariableNames = new Dictionary<string, int>();
-			currentLowerCaseTypeOrMemberNames = CollectAllLowerCaseTypeOrMemberNames(function.Method.DeclaringTypeDefinition).ToArray();
+			currentLowerCaseTypeOrMemberNames = new List<string>();
+			var currentLowerCaseMemberNames = CollectAllLowerCaseMemberNames(function.Method.DeclaringTypeDefinition);
+			foreach (var name in currentLowerCaseMemberNames)
+				currentLowerCaseTypeOrMemberNames.Add(name);
+			var currentLowerCaseTypeNames = CollectAllLowerCaseTypeNames(function.Method.DeclaringTypeDefinition);
+			foreach (var name in currentLowerCaseTypeNames)
+			{
+				currentLowerCaseTypeOrMemberNames.Add(name);
+				AddExistingName(reservedVariableNames, name);
+			}
 			localFunctionMapping = new Dictionary<MethodDefinitionHandle, string>();
 			loopCounters = CollectLoopCounters(function);
 			foreach (var f in function.Descendants.OfType<ILFunction>())
@@ -147,26 +156,27 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			}
 		}
 
-		IEnumerable<string> CollectAllLowerCaseTypeOrMemberNames(ITypeDefinition type)
+		static IEnumerable<string> CollectAllLowerCaseMemberNames(ITypeDefinition type)
 		{
 			foreach (var item in type.GetMembers(m => IsLowerCase(m.Name)))
 				yield return item.Name;
+		}
+
+		static IEnumerable<string> CollectAllLowerCaseTypeNames(ITypeDefinition type)
+		{
 
 			foreach (var item in type.ParentModule.TopLevelTypeDefinitions)
 			{
 				if (item.Namespace != type.Namespace)
 					continue;
 				if (IsLowerCase(item.Name))
-				{
-					AddExistingName(reservedVariableNames, item.Name);
 					yield return item.Name;
-				}
 			}
+		}
 
-			static bool IsLowerCase(string name)
-			{
-				return name.Length > 0 && char.ToLower(name[0]) == name[0];
-			}
+		static bool IsLowerCase(string name)
+		{
+			return name.Length > 0 && char.ToLower(name[0]) == name[0];
 		}
 
 		bool IsSetOrEventAccessor(IMethod method)
@@ -678,7 +688,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				return variableType;
 		}
 
-		static Dictionary<string, int> CollectReservedVariableNames(ILFunction function, ILVariable existingVariable)
+		static Dictionary<string, int> CollectReservedVariableNames(ILFunction function,
+			ILVariable existingVariable, bool mustResolveConflicts)
 		{
 			var reservedVariableNames = new Dictionary<string, int>();
 			var rootFunction = function.Ancestors.OfType<ILFunction>().Single(f => f.Parent == null);
@@ -694,12 +705,18 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 						AddExistingName(reservedVariableNames, v.Name);
 				}
 			}
-			foreach (var f in rootFunction.Method.DeclaringTypeDefinition.GetFields().Select(f => f.Name))
-				AddExistingName(reservedVariableNames, f);
+			if (mustResolveConflicts)
+			{
+				var memberNames = CollectAllLowerCaseMemberNames(function.Method.DeclaringTypeDefinition)
+					.Concat(CollectAllLowerCaseTypeNames(function.Method.DeclaringTypeDefinition));
+				foreach (var name in memberNames)
+					AddExistingName(reservedVariableNames, name);
+			}
 			return reservedVariableNames;
 		}
 
-		internal static string GenerateForeachVariableName(ILFunction function, ILInstruction valueContext, ILVariable existingVariable = null)
+		internal static string GenerateForeachVariableName(ILFunction function, ILInstruction valueContext,
+			ILVariable existingVariable = null, bool mustResolveConflicts = false)
 		{
 			if (function == null)
 				throw new ArgumentNullException(nameof(function));
@@ -707,7 +724,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			{
 				return existingVariable.Name;
 			}
-			var reservedVariableNames = CollectReservedVariableNames(function, existingVariable);
+			var reservedVariableNames = CollectReservedVariableNames(function, existingVariable, mustResolveConflicts);
 
 			string baseName = GetNameFromInstruction(valueContext);
 			if (string.IsNullOrEmpty(baseName))
@@ -756,11 +773,13 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			}
 		}
 
-		internal static string GenerateVariableName(ILFunction function, IType type, ILInstruction valueContext = null, ILVariable existingVariable = null)
+		internal static string GenerateVariableName(ILFunction function, IType type,
+			ILInstruction valueContext = null, ILVariable existingVariable = null,
+			bool mustResolveConflicts = false)
 		{
 			if (function == null)
 				throw new ArgumentNullException(nameof(function));
-			var reservedVariableNames = CollectReservedVariableNames(function, existingVariable);
+			var reservedVariableNames = CollectReservedVariableNames(function, existingVariable, mustResolveConflicts);
 
 			string baseName = valueContext != null ? GetNameFromInstruction(valueContext) ?? GetNameByType(type) : GetNameByType(type);
 			string proposedName = "obj";