#1572: Do not generate variable names that match C# keywords.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.cs

@@ -4943,8 +4943,8 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 
 		public void Issue1779(int value)
 		{
-			CustomStruct2 @struct = GetStruct();
+			CustomStruct2 customStruct = GetStruct();
-			@struct.IntProp += value;
+			customStruct.IntProp += value;
 		}
 	}
 }

ICSharpCode.Decompiler.Tests/TestCases/Pretty/RefLocalsAndReturns.cs

@@ -182,11 +182,11 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			GetRef<ReadOnlyStruct>().Method();
 
 			// call on a copy, not the original ref:
-			NormalStruct @ref = GetRef<NormalStruct>();
+			NormalStruct normalStruct = GetRef<NormalStruct>();
-			@ref.Method();
+			normalStruct.Method();
 
-			ReadOnlyStruct ref2 = GetRef<ReadOnlyStruct>();
+			ReadOnlyStruct readOnlyStruct = GetRef<ReadOnlyStruct>();
-			ref2.Method();
+			readOnlyStruct.Method();
 		}
 
 		public void CallOnReadOnlyRefReturn()
@@ -293,13 +293,13 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 
 		public void RefReassignment(ref NormalStruct s)
 		{
-			ref NormalStruct @ref = ref GetRef<NormalStruct>();
+			ref NormalStruct reference = ref GetRef<NormalStruct>();
-			RefReassignment(ref @ref);
+			RefReassignment(ref reference);
 			if (s.GetHashCode() == 0)
 			{
-				@ref = ref GetRef<NormalStruct>();
+				reference = ref GetRef<NormalStruct>();
 			}
-			RefReassignment(ref @ref.GetHashCode() == 4 ? ref @ref : ref s);
+			RefReassignment(ref reference.GetHashCode() == 4 ? ref reference : ref s);
 		}
 
 		public static void Main(string[] args)

ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs

@@ -1,4 +1,4 @@
-// Copyright (c) 2010-2020 AlphaSierraPapa for the SharpDevelop Team
+// Copyright (c) 2010-2020 AlphaSierraPapa for the SharpDevelop Team
 // 
 // 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
@@ -426,8 +426,9 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 
 		/// <summary>
 		/// Determines whether the specified identifier is a keyword in the given context.
+		/// If <paramref name="context"/> is <see langword="null" /> all keywords are treated as unconditional.
 		/// </summary>
-		public static bool IsKeyword(string identifier, AstNode context)
+		public static bool IsKeyword(string identifier, AstNode context = null)
 		{
 			// only 2-10 char lower-case identifiers can be keywords
 			if (identifier.Length > maxKeywordLength || identifier.Length < 2 || identifier[0] < 'a')
@@ -440,10 +441,12 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 			}
 			if (queryKeywords.Contains(identifier))
 			{
-				return context.Ancestors.Any(ancestor => ancestor is QueryExpression);
+				return context == null || context.Ancestors.Any(ancestor => ancestor is QueryExpression);
 			}
 			if (identifier == "await")
 			{
+				if (context == null)
+					return true;
 				foreach (AstNode ancestor in context.Ancestors)
 				{
 					// with lambdas/anonymous methods,

ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs

@@ -657,8 +657,10 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 
 			if (name.Length == 0)
 				return "obj";
-			else
+			string lowerCaseName = char.ToLower(name[0]) + name.Substring(1);
-				return char.ToLower(name[0]) + name.Substring(1);
+			if (CSharp.OutputVisitor.CSharpOutputVisitor.IsKeyword(lowerCaseName))
+				return null;
+			return lowerCaseName;
 		}
 
 		internal static IType GuessType(IType variableType, ILInstruction inst, ILTransformContext context)