Add transform to fix name collisions.

This allows us to decompile events to valid code without having to match the compiler-generated event pattern.

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -69,6 +69,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			new ConvertConstructorCallIntoInitializer(), // must run after DeclareVariables
 			new DecimalConstantTransform(),
 			new IntroduceUsingDeclarations(),
+			new FixNameCollisions(),
 			//new IntroduceExtensionMethods(context), // must run after IntroduceUsingDeclarations
 			//new IntroduceQueryExpressions(context), // must run after IntroduceExtensionMethods
 			//new CombineQueryExpressions(context),

ICSharpCode.Decompiler/CSharp/Transforms/EscapeInvalidIdentifiers.cs

@@ -15,6 +15,7 @@
 // FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
+
 using System;
 using System.Linq;
 using ICSharpCode.NRefactory.CSharp;
@@ -27,7 +28,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 	/// <remarks>
 	/// This transform is not enabled by default.
 	/// </remarks>
-	public 	class EscapeInvalidIdentifiers : IAstTransform
+	public class EscapeInvalidIdentifiers : IAstTransform
 	{
 		bool IsValid(char ch)
 		{

ICSharpCode.Decompiler/CSharp/Transforms/FixNameCollisions.cs

@@ -0,0 +1,80 @@
+// Copyright (c) 2016 Daniel Grunwald
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using ICSharpCode.NRefactory.CSharp;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.Decompiler.CSharp.Transforms
+{
+	/// <summary>
+	/// Rename entities to solve name collisions that make the code uncompilable.
+	/// </summary>
+	/// <remarks>
+	/// Currently, we only rename private fields that collide with property or event names.
+	/// This helps especially with compiler-generated events that were not detected as a pattern.
+	/// </remarks>
+	public class FixNameCollisions : IAstTransform
+	{
+		public void Run(AstNode rootNode, TransformContext context)
+		{
+			var renamedSymbols = new Dictionary<ISymbol, string>();
+			foreach (var typeDecl in rootNode.DescendantsAndSelf.OfType<TypeDeclaration>()) {
+				var memberNames = typeDecl.Members.Select(m => m.Name).ToHashSet();
+				// memberNames does not include fields or non-custom events because those
+				// don't have a single name, but a list of VariableInitializers.
+				foreach (var fieldDecl in typeDecl.Members.OfType<FieldDeclaration>()) {
+					if (fieldDecl.Variables.Count != 1)
+						continue;
+					string oldName = fieldDecl.Variables.Single().Name;
+					if (memberNames.Contains(oldName)) {
+						string newName = PickNewName(memberNames, oldName);
+						ISymbol symbol = fieldDecl.GetSymbol();
+						if (symbol != null) {
+							fieldDecl.Variables.Single().Name = newName;
+							renamedSymbols[symbol] = newName;
+						}
+					}
+				}
+			}
+			
+			foreach (var node in rootNode.DescendantsAndSelf) {
+				if (node is IdentifierExpression || node is MemberReferenceExpression) {
+					ISymbol symbol = node.GetSymbol();
+					string newName;
+					if (symbol != null && renamedSymbols.TryGetValue(symbol, out newName)) {
+						node.GetChildByRole(Roles.Identifier).Name = newName;
+					}
+				}
+			}
+		}
+
+		string PickNewName(ISet<string> memberNames, string name)
+		{
+			if (!memberNames.Contains("m_" + name))
+				return "m_" + name;
+			for (int num = 2;; num++) {
+				string newName = name + num;
+				if (!memberNames.Contains(newName))
+					return newName;
+			}
+		}
+	}
+}

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -66,6 +66,7 @@
     <Compile Include="CSharp\DecompilerSettings.cs" />
     <Compile Include="CSharp\Transforms\DecimalConstantTransform.cs" />
     <Compile Include="CSharp\Transforms\EscapeInvalidIdentifiers.cs" />
+    <Compile Include="CSharp\Transforms\FixNameCollisions.cs" />
     <Compile Include="CSharp\Transforms\IntroduceUsingDeclarations.cs" />
     <Compile Include="CSharp\Transforms\TransformContext.cs" />
     <Compile Include="CSharp\TranslatedExpression.cs" />