Fix IDE0044 Make field readonly

Author: vweijsters

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/OrderingRules/UsingCodeFixProvider.TreeTextSpan.cs

@@ -158,7 +158,7 @@ internal TreeTextSpan GetContainingSpan(TextSpan textSpan)
             internal class Builder
             {
                 private readonly List<Builder> children = new List<Builder>();
-                private int start;
+                private readonly int start;
                 private int end = int.MaxValue;
 
                 /// <summary>

StyleCop.Analyzers/StyleCop.Analyzers.Status.Generator/SolutionReader.cs

@@ -24,7 +24,7 @@ namespace StyleCop.Analyzers.Status.Generator
     /// </summary>
     public class SolutionReader
     {
-        private static Regex diagnosticPathRegex = new Regex(@"(?<type>[A-Za-z]+)Rules\\(?<name>[A-Za-z0-9]+)\.cs$");
+        private static readonly Regex diagnosticPathRegex = new Regex(@"(?<type>[A-Za-z]+)Rules\\(?<name>[A-Za-z0-9]+)\.cs$");
         private INamedTypeSymbol diagnosticAnalyzerTypeSymbol;
         private INamedTypeSymbol noCodeFixAttributeTypeSymbol;
 

StyleCop.Analyzers/StyleCop.Analyzers/MaintainabilityRules/SA1412StoreFilesAsUtf8.cs

@@ -39,7 +39,7 @@ internal class SA1412StoreFilesAsUtf8 : DiagnosticAnalyzer
 
         private static readonly Action<SyntaxTreeAnalysisContext> SyntaxTreeAction = HandleSyntaxTree;
 
-        private static byte[] utf8Preamble = Encoding.UTF8.GetPreamble();
+        private static readonly byte[] utf8Preamble = Encoding.UTF8.GetPreamble();
 
         /// <summary>
         /// Gets the key for the detected encoding name in the <see cref="Diagnostic.Properties"/> collection.