Fix handling escaped identifiers in using directives

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test/OrderingRules/SA1208UnitTests.cs

@@ -44,6 +44,20 @@ class A
             await this.VerifyCSharpDiagnosticAsync(usingsInNamespaceDeclaration, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        public async Task TestSystemUsingDirectivesWithEscapeSequenceAsync()
+        {
+            string usingsInNamespaceDeclaration = @"namespace Test
+{
+    using @System;
+    using System.Diagnostics;
+    using \u0053ystem.IO;
+    using System.Threading;
+}";
+
+            await this.VerifyCSharpDiagnosticAsync(usingsInNamespaceDeclaration, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+        }
+
         [Fact]
         public async Task TestWhenSystemUsingDirectivesAreNotOnTopInCompilationAsync()
         {

StyleCop.Analyzers/StyleCop.Analyzers/Helpers/UsingDirectiveSyntaxHelpers.cs

@@ -21,7 +21,7 @@ internal static class UsingDirectiveSyntaxHelpers
         /// </summary>
         /// <param name="usingDirective">The <see cref="UsingDirectiveSyntax"/> that will be checked.</param>
         /// <returns>Return true if the <see cref="UsingDirectiveSyntax"/>is system using directive, otherwise false.</returns>
-        internal static bool IsSystemUsingDirective(this UsingDirectiveSyntax usingDirective) => string.Equals(SystemUsingDirectiveIdentifier, GetFirstIdentifierInUsingDirective(usingDirective)?.Text, StringComparison.Ordinal);
+        internal static bool IsSystemUsingDirective(this UsingDirectiveSyntax usingDirective) => string.Equals(SystemUsingDirectiveIdentifier, GetFirstIdentifierInUsingDirective(usingDirective)?.ValueText, StringComparison.Ordinal);
 
         /// <summary>
         /// Check if <see cref="UsingDirectiveSyntax"/> is preceded by a preprocessor directive.